JP5257759B2 - Inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method for inspecting the surface of an object represented by a semiconductor wafer or the like.

  2. Description of the Related Art A semiconductor manufacturing apparatus that forms a circuit pattern on a semiconductor wafer (hereinafter referred to as a wafer as appropriate) has been well known in the past, but this semiconductor manufacturing is performed through a variety of complicated processes. It is necessary to inspect whether there are any defects or abnormalities in the circuit pattern formed on the substrate, and to inspect for dust attached to the wafer, scratches on the wafer surface, or the like. This is because, for example, if there is a scratch on the wafer, the wafer is cracked or broken during the semiconductor manufacturing process, and the previous manufacturing process is wasted.

  In a semiconductor manufacturing process, when a predetermined circuit pattern is exposed on the surface of a wafer on which a resist is applied, the resist is again processed through many steps such as development, etching, sputtering, doping, and CMP (chemical mechanical polishing). After the application, another circuit pattern is exposed, and then a plurality of layers are stacked through the same process. In such a semiconductor manufacturing process, it is preferable to inspect the wafer in each step, but it is particularly important to inspect the circuit pattern that can be reproduced when there is a defect, and the inspection that is performed at the end of the development process. .

For inspection of such wafers, a micro-inspection in which a circuit pattern or the like is enlarged by a scanning electron microscope (SEM) to observe the circuit pattern or the like, and a bright field observation or a dark field observation of a specular reflection image or a diffraction image There is known a macro inspection (see, for example, Patent Document 1). The macro inspection is an important inspection because a high throughput can be obtained because the wafer can be observed collectively. Conventionally, such macro inspection has been carried out by human eyes. However, the importance of macro inspection apparatuses is increasing as circuit patterns become finer and wafers become larger.
JP 2002-162368 A

  In the macro inspection, light in a desired wavelength band is extracted from light emitted from a light source such as an ultrahigh pressure mercury lamp as inspection irradiation light using a wavelength selection filter such as an interference filter. For this reason, the wavelength selective filter is heated by light from the light source, which may affect the optical performance. Further, with the miniaturization of circuit patterns, it is necessary to shorten the wavelength of the irradiation light for inspection used for diffraction inspection. Specifically, from the h-line (405 nm) to the i-line (365 nm), it has recently become necessary to use light in the 248 nm wavelength band. Conventionally used h-line and i-line are mercury emission line spectra, so even if the transmission wavelength band of the wavelength selection filter is slightly shifted, the emission line spectrum does not change, and the emission line spectrum is in the transmission region of the wavelength selection filter. If so, there was little effect on the extracted wavelength. However, the light in the 248 nm wavelength band such as an ultra-high pressure mercury lamp has a relatively broad peak, and the wavelength of the inspection irradiation light also shifts when the transmission wavelength band of the wavelength selection filter that extracts the irradiation light for inspection shifts. There is an increased possibility of inconvenience. In addition, such a shift in wavelength may progress differently for each apparatus, and there is a possibility that variations in inspection results (so-called inter-apparatus errors) occur between a plurality of inspection apparatuses.

  The present invention has been made in view of such a problem, and is capable of accurate inspection that is not affected by wavelength fluctuations of inspection illumination light, and suppresses variations in inspection results among a plurality of inspection apparatuses. It is an object of the present invention to provide an inspection apparatus and an inspection method capable of improving the process control accuracy.

In order to achieve such an object, an inspection apparatus according to the present invention includes an irradiation unit that irradiates a test object with inspection irradiation light, and irradiation of the inspection irradiation light in advance according to the wavelength of the inspection irradiation light. A modulation unit that emits inspection light that causes a set physical modulation; and an inspection light that is irradiated with the inspection irradiation light and receives the physical modulation at the test object and the modulation unit. A light receiving unit that receives light, an inspection unit that inspects the test object based on inspection light that has undergone physical modulation by the test object received by the light receiving unit, and an inspection state that detects the state of the inspection An inspection light that has been subjected to the physical modulation by the test object and an inspection light that has been subjected to the physical modulation by the modulation unit within a range that can be simultaneously received by the light receiving unit. The test object and the modulation unit are disposed on the inspection state detection unit. It detects the state of the inspection based on the inspection light received the physical modulation in parts, and a plurality of the modulated portions corresponding to the inspection illumination light of a plurality of different wavelengths.

Incidentally, in the inspection apparatus described above, a plurality of the modulation section are preferably arranged in a plurality of different positions. Further, it is preferable that a plurality of the modulation units having the same physical modulation characteristics are provided at symmetrical positions via the test object.

Further, the inspection apparatus according to the present invention includes an irradiation unit that irradiates the inspection object with the irradiation light for inspection, and irradiation with the irradiation light for inspection, and physical modulation set in advance according to the wavelength of the irradiation light for inspection And a light receiving unit that receives the inspection light that has been irradiated with the inspection irradiation light and is subjected to the physical modulation in the modulation unit. An inspection unit that inspects the inspection object based on inspection light that has received the physical modulation in the inspection object received by the light receiving unit, and an inspection state detection unit that detects the state of the inspection, The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit, and the inspection state detection unit is the modulation unit and the physical modulation Wherein detecting the state of the inspection on the basis of the inspection light received, a plurality of the modulating portion having a property equivalent the physical modulation, configured with a symmetrical position through the test object.

In the inspection apparatus described above, it is preferable that the light receiving surface for the irradiation light for inspection of the modulation unit and the light receiving surface for the irradiation light for inspection of the test object are arranged substantially in the same plane.

  In the above-described inspection apparatus, it is preferable that a support unit that supports the test object is provided, and the modulation unit is disposed in the vicinity of the support unit. Or it is preferable that the said modulation | alteration part is arrange | positioned at the said support part. In this case, the support unit tilts the test object, so that the inspection light is incident on the test object and the light receiving unit of the test light subjected to the physical modulation on the test object. It is preferable that the light receiving position of the test object can be adjusted, and the tilt axis of the test object passes through the vicinity of the center of the test object and is set substantially on the same plane as the light reception surface of the test object or in the vicinity of the same plane. .

  Moreover, in the above-described inspection apparatus, it is preferable that the modulation unit is disposed in the vicinity of the tilt axis. Alternatively, the modulation unit is symmetric with respect to the test object in the vicinity of the tilt axis and symmetric with respect to the test object in the vicinity of the orthogonal axis perpendicular to the tilt axis near the center of the test object. It is preferable that they are arranged at various positions.

  In the inspection apparatus described above, it is preferable that the inspection state detection unit detects the state of the inspection based on the preset physical modulation. In this case, it is preferable that the inspection state detection unit detects the inspection state based on diffracted light or specularly reflected light generated by the modulation unit.

Further, the inspection apparatus according to the present invention includes an irradiation unit that irradiates the inspection object with the irradiation light for inspection, and irradiation with the irradiation light for inspection, and physical modulation set in advance according to the wavelength of the irradiation light for inspection And a light receiving unit that receives the inspection light that has been irradiated with the inspection irradiation light and is subjected to the physical modulation in the modulation unit. An inspection unit that inspects the inspection object based on inspection light that has received the physical modulation in the inspection object received by the light receiving unit, and an inspection state detection unit that detects the state of the inspection, The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit, and the inspection state detection unit is the modulation unit and the physical modulation Based on the inspection light received detects the state of the inspection, the inspection state detecting unit, on the basis of the inspection light receiving said physical modulated by the modulation unit, the incident angle of the inspection illumination light, the inspection Wavelength of irradiation light, tilt angle of the test object, light receiving position of the inspection light subjected to the physical modulation by the light receiving unit, and azimuth angle of the test object when the test object is rotated It is configured to detect the state of at least one of the examinations.

In the inspection apparatus described above, it is preferable that the inspection state detection unit detects the wavelength of the irradiation light for inspection based on a light receiving position of diffracted light generated by the modulation unit by the light receiving unit.

  Further, in the above-described inspection apparatus, the inspection state detection unit includes the modulation unit disposed in the vicinity of an orthogonal axis orthogonal to a tilt axis that tilts the test object and the modulation unit, or the test object in the orthogonal axis direction. The inspection light that has undergone the physical modulation at the side of the optical axis and the inspection light that has undergone the physical modulation at the modulation unit disposed near the tilt axis or the test object near the tilt axis are predetermined. When there is a difference in luminance exceeding the reference range, it is preferable to detect a defect in the tilt angle of the test object.

  In the inspection apparatus described above, the inspection state detection unit includes the inspection light that has been subjected to the physical modulation by the modulation unit, and the vicinity of the orthogonal axis that is orthogonal to the tilt axis that tilts the test object and the modulation unit. When the inspection object or the inspection light subjected to the physical modulation at the side of the inspection object in the direction of the tilt axis has a luminance difference exceeding a predetermined reference range, the azimuth angle of the inspection object It is preferable to detect defects.

  In the inspection apparatus described above, the inspection state detection unit may be configured such that the inspection light subjected to the physical modulation by the modulation units arranged at a plurality of different positions deviates from a predetermined reference range to the same extent. Further, it is preferable to detect at least one of the illumination optical system of the irradiating unit and the light receiving optical system or the light receiving sensitivity of the light receiving unit.

Further, the inspection apparatus according to the present invention includes an irradiation unit that irradiates the inspection object with the irradiation light for inspection, and irradiation with the irradiation light for inspection, and physical modulation set in advance according to the wavelength of the irradiation light for inspection And a light receiving unit that receives the inspection light that has been irradiated with the inspection irradiation light and is subjected to the physical modulation in the modulation unit. An inspection unit that inspects the inspection object based on inspection light that has received the physical modulation in the inspection object received by the light receiving unit, and an inspection state detection unit that detects the state of the inspection, The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit, and the inspection state detection unit is the modulation unit and the physical modulation Examination received on the basis of the inspection light detecting a wavelength of at least the inspection illumination light as the state of the test was to set or change the tilt angle of the test object on the basis of the wavelength detected by the inspection state detector It is configured with a state control unit.

Further, the inspection method according to the present invention is to inspect the inspection object based on the inspection light that is irradiated with the inspection irradiation light and is physically modulated by the inspection object. The inspection irradiation light is applied to the test object and a modulation unit that receives irradiation of the inspection irradiation light and causes the inspection irradiation light to generate the physical modulation set in advance according to the wavelength of the inspection irradiation light. A first step of receiving the inspection light emitted by receiving the physical modulation by the test object and the modulation unit, and the physical object by the test object received in the first step performs inspection of the test object on the basis of the inspection light being modulated, have a second step of detecting a state of the inspection based on the inspection light received the physical modulated by the modulation section In the first step, the inspection irradiation light having a plurality of different wavelengths is applied. In the second step, the modulation unit corresponding to the inspection portion of the test object among the plurality of modulation units is received in the second step. The state of the inspection is detected based on the inspection light subjected to physical modulation .

  Further, in the inspection method described above, diffracted light or specularly reflected light generated in the test object and the modulation unit is received in the first step, and generated in the test object in the second step. Preferably, the inspection object is inspected based on diffracted light or specularly reflected light, and the state of the inspection is detected based on diffracted light or specularly reflected light generated by the modulation unit.

  Further, in the inspection method described above, by tilting the test object, the incident angle of the test irradiation light to the test object and the light receiving position of the test light subjected to the physical modulation by the test object are determined. The tilt axis of the test object passes through the vicinity of the center of the test object and is set substantially on the same plane as or near the same plane as the light receiving surface of the test irradiation light of the test object. In the second step, based on the inspection light subjected to the physical modulation by the modulation unit, the incident angle of the inspection irradiation light, the wavelength of the inspection irradiation light, the tilt angle of the test object, It is preferable to detect the inspection state of at least one of a light receiving position of the inspection light subjected to the physical modulation and an azimuth angle of the inspection object when the inspection object is rotated.

  In the inspection method described above, in the first step, diffracted light generated in the modulation unit is received, and in the second step, based on a light receiving position of the diffracted light received in the first step. It is preferable to detect the wavelength of the irradiation light for inspection.

  Further, in the inspection method described above, in the second step, the modulation unit disposed in the vicinity of the orthogonal axis orthogonal to the tilt axis in the vicinity of the center of the inspection object or the test object in the orthogonal axis direction. The inspection light that has undergone the physical modulation at the side and the inspection light that has undergone the physical modulation at the modulation unit disposed near the tilt axis or the test object near the tilt axis are a predetermined reference. When there is a difference in luminance exceeding the range, it is preferable to detect a defect in the tilt angle of the test object.

  Further, in the inspection method described above, in the second step, the inspection light that has undergone the physical modulation in the modulation unit and the inspection object in the vicinity of the orthogonal axis or the inspection object in the direction of the tilt axis It is preferable that a defect in the azimuth angle of the test object is detected when the inspection light subjected to the physical modulation at the side portion has a luminance difference exceeding a predetermined reference range.

  In the inspection method described above, in the second step, when the inspection light that has undergone the physical modulation by the modulation units arranged at a plurality of different positions deviates from a predetermined reference range to the same extent. Further, it is preferable to detect at least one of the illumination optical system of the irradiating unit and the light receiving optical system or the light receiving sensitivity of the light receiving unit.

  The inspection apparatus preferably includes a third step of setting or changing the state of the inspection based on the state of the inspection detected in the second step. In this case, in the third step, it is preferable to set or change the tilt angle of the test object based on the wavelength detected in the second step.

  According to the present invention, it is possible to perform an accurate inspection with reduced influence of wavelength variation of the irradiation light for inspection, and there is no variation in inspection results among a plurality of inspection apparatuses, thereby improving the process management accuracy of the semiconductor manufacturing process. It becomes possible.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. An example of an inspection apparatus to which the present invention is applied is shown in FIG. 1, and a surface defect (abnormality) of a semiconductor wafer 5 (hereinafter simply referred to as a wafer 5), which is an object to be inspected, is inspected by this apparatus. The inspection apparatus 1 receives a holder mechanism 40 for mounting and holding the wafer 5, an illumination optical system 10 that irradiates the wafer 5 with inspection illumination light (hereinafter simply referred to as illumination light), and illumination light irradiation. The condensing optical system 20 that condenses the reflected light, diffracted light, etc. (inspection light) from the wafer 5 and the inspection light collected by the condensing optical system 20 are received to detect the image of the wafer 5. And an imaging device 30.

  As shown in FIG. 2, the holder mechanism 40 includes a holder portion 41 that fixes and supports the wafer 5 on the wafer placement surface, and a part (center portion) of the wafer placement surface of the holder portion 41. A wafer table 42 whose mounting surface can be driven in the vertical direction and rotational direction, a table drive unit 43 that moves the wafer table 42 up and down, and a wafer table 42 that are integrated with the wafer table 42 to drive the driving force of the table drive unit 43 to the wafer. A drive transmission portion 44 that transmits to the table 42 and a pair of tilt shaft portions 45 that receive a driving force from a tilt drive mechanism (not shown) when the entire holder mechanism 40 is driven to tilt (tilt) and serve as a drive shaft are provided. ing.

  The wafer mounting surface of the holder unit 41 is processed to be lower than the upper surface of the holder mechanism 40 by the thickness of the wafer 5, and further, a suction groove (not shown) is provided. Can be fixedly supported by vacuum chucking (vacuum adsorption). Further, the side wall portion 41 a of the holder portion 41 functions as a guide for the wafer 5. When the table drive unit 43 receives the wafer 5 transferred by a wafer transfer mechanism (not shown), the table drive unit 43 raises the wafer table 42 (a state indicated by a broken line in FIG. 2B) from the wafer transfer mechanism. , And stops in a state where the wafer placement surface of the wafer table 42 is substantially flush with the wafer placement surface of the holder portion 41. In addition, you may descend | fall slightly from substantially the same plane.

  The table driving unit 43 includes a rotation position detection encoder (not shown), and based on the alignment information of the wafer 5 (alignment mark position information on the wafer 5), the center of the wafer 5 (wafer table 42 and drive transmission). Rotating around the axis Ax1 (hereinafter referred to as the vertical axis Ax1) that passes through the center of the portion 44 and is perpendicular to the wafer 5 (rotating while maintaining the wafer surface in the same plane), the azimuth angle of the wafer 5 ( The wafer 5 can be fixedly supported by the holder portion 41 in a state where the rotation angle) is accurately positioned. Further, a tilt shaft portion is arranged by a tilt drive mechanism (not shown) around an axis (preferably an axis passing through the surface of the wafer 5) Ax2 (hereinafter referred to as a tilt axis Ax2) parallel to the surface of the wafer 5 fixedly supported in this way. The entire holder mechanism 40 can be tilted through 45.

  The inspection apparatus 1 has an observation unit (not shown) that can observe the wafer 5 fixedly supported by the holder mechanism 40, and observes an alignment mark (not shown) formed on the wafer 5 to observe the wafer. 5 is detected, and the above-described alignment of the wafer 5 is possible.

  The illumination optical system 10 has a light source 11 such as a metal halide lamp or an ultra-high pressure mercury lamp, a collector lens 12 that collects the illumination light beam from the light source 11, and a wavelength through which the illumination light beam collected by the collector lens 12 is transmitted. A wavelength selection filter 13 that performs selection and a neutral density filter 14 that adjusts the amount of light (hereinafter referred to as ND filter 14) are provided. Furthermore, an illumination lens having an input lens 15 that condenses the illumination light beam that has passed through the filters 13 and 14 is provided, and the illumination light condensed by the input lens 15 is introduced into one end 16 a of the fiber 16.

  Here, the wavelength selection filter 13 is provided in a disk (turret) 13b having a switching drive mechanism 13a, and several types of filters can be switched and used by the switching drive mechanism 13a. Yes. For example, an interference filter that transmits light of a specific wavelength such as i-line (wavelength 365 nm) or 248 nm band, a band-pass filter that transmits light of a specific wavelength band, or only light of a wavelength longer than a predetermined wavelength. A sharp cut filter or the like to be used can be selected and used as necessary. The ND filter 14 is composed of a disk-shaped filter in which the amount of transmitted light sequentially changes according to the rotation angle, and is configured to be able to control the amount of transmitted light by being rotationally controlled by the rotation drive mechanism 14a.

  The fiber 16 in which the illumination light is incident from the one end 16a branches in the middle, one exits from the other end 16b, and the other exits from the other end 16c. Illumination light emitted from the other end 16 c is incident on the illuminometer 18 and can detect light energy applied to the wavelength selection filter 13. Since the number of fibers at the other end 16b and the other end 16c is randomly distributed to about 1000 to 1, the amount of light emitted from the other end 16b and the other end 16c is about 1000 to 1, respectively.

  The illumination optical system 10 further includes an illumination system concave mirror 17 that receives a divergent light beam emitted from the other end 16 b of the fiber 16, and the other end 16 b of the fiber 16 is disposed at a substantially focal position of the illumination system concave mirror 17. ing. For this reason, the illumination light introduced into one end 16a of the fiber 16 and diverged and irradiated from the other end 16b of the fiber 16 to the illumination system concave mirror 17 is supported by the holder mechanism 40 as a substantially parallel light beam by the illumination system concave mirror 17. The surface of the wafer 5 is irradiated. At this time, the illumination light beam irradiated onto the surface of the wafer 5 is irradiated with an angle θi with respect to an axis (vertical axis) Ax1 perpendicular to the surface of the wafer 5, and the light (inspection light) from the wafer 5 is angled. It is emitted with θr. The relationship between the incident angle θi and the outgoing angle θr can be adjusted by tilting (tilting) the holder mechanism 40 about the tilt axis Ax2. That is, the relationship between the incident angle θi and the outgoing angle θr can be adjusted by changing the mounting angle of the wafer 5 by the tilt of the holder mechanism 40.

  Light emitted from the surface of the wafer 5 (here, diffracted light is used) is collected by the condensing optical system 20. The condensing optical system 20 includes a condensing concave mirror 21 disposed opposite to a direction having an angle θr with respect to the vertical axis Ax1, and a condensing position (focal position) of the condensing concave mirror 21. The diaphragm 22 is disposed, and an imaging lens 23 disposed on the rear side of the diaphragm 22. An imaging device 30 is disposed on the rear side of the imaging lens 23. The outgoing light (n-order diffracted light) that is condensed by the condensing concave mirror 21 and restricted by the diaphragm 22 is imaged on the CCD image sensor (image device) 31 of the imaging device 30 by the imaging lens 23. . As a result, a diffraction image (image by diffracted light) of the surface of the wafer 5 is detected by the CCD image pickup device 31.

  The CCD image sensor 31 photoelectrically converts an image (diffracted light image) on the wafer surface formed on the image receiving surface to generate an image signal, and outputs the image signal to the image processing inspection device 35. Inside the image processing inspection apparatus 35, there are a control unit 37, an inspection state detection unit 38 for detecting a state (inspection state) at the time of diffraction image detection by the CCD imaging device 31, and a defect detection unit for detecting defects on the wafer 5. 39 and a memory (storage device) 36 are provided.

  The control unit 37 performs switching operation control of the wavelength selection filter 13 by the switching drive mechanism 13a, rotation control of the ND filter 14 by the rotation drive mechanism 14a, rotation control of the holder mechanism 40 (wafer table 42) around the vertical axis Ax1, Tilt control of the holder mechanism 40 about the tilt axis Ax2 is performed. Further, the control unit 37 converts the image of the wafer 5 obtained from the CCD image sensor 31 into a digital image of a predetermined bit (for example, 16 bits). When determining the optimum tilt angle of the wafer 5, the control unit 37 configured as described above captures an image of the wafer 5 while changing the tilt angle, and sequentially stores digital images at different tilt angles in the memory 36.

  The memory (storage device) 36 stores the digital image from the control unit 37 and the inspection state at that time (tilt angle of the holder mechanism 40, wavelength of illumination light, rotation angle of the wafer holder 42, etc.). The stored digital image is output to the inspection state detection unit 38 when an inspection state is detected, and to the defect detection unit 39 when a defect of the wafer 5 is detected.

  When detecting the inspection state, the inspection state detection unit 38 takes in the digital image of the wafer 5 and the reference modulation unit 50 described later, and stores the incident angle θi and the emission angle θr of illumination light (that is, the holder mechanism 40). Tilt angle), the wavelength of the illumination light, and the inspection state such as the azimuth angle (rotation angle) about the vertical axis Ax1 of the wafer holder 42 (wafer 5).

  The defect detection unit 39, when detecting a defect on the wafer 5, captures a digital image of the wafer 5 stored in the memory 36 and performs image processing, and also monitors the light quantity of the image and determines the wafer 5 based on the brightness of the image. Defect locations such as film thickness unevenness / coating unevenness (portions where no film is formed due to the influence of dust, etc.), pattern shape abnormalities, scratches, and the like are specified.

  Here, periodically repeated circuit patterns (hereinafter simply referred to as patterns) are formed on the surface of the wafer 5 as the test object, and these patterns are formed on the surface of the wafer 5. Lines (linear protrusions) are periodically and repeatedly arranged. For this reason, when the repetition pitch of the lines constituting the pattern is p and the wavelength of the illumination light is λ, the holder mechanism 40 is tilted to obtain the tilt angle T of the surface of the wafer 5 by the following equation (1). With this setting, the nth-order diffracted light emitted from the wafer 5 is condensed on the imaging device 30 (CCD imaging element 31) via the condensing optical system 20. In this manner, the presence or absence of defects such as an abnormal line width of the pattern is inspected from the image of the surface of the wafer 5 obtained by the CCD image pickup device 31 by receiving the nth order diffracted light.

(Equation 1)
sin (θi−T) −sin (θr + T) = n · λ / p (1)

  In Expression (1), θi and θr are values of the incident angle and the outgoing angle before the tilt angle T is changed (when the tilt angle T = 0), that is, initial values. When the tilt angle T is changed, the incident angle (θi−T) and the emission angle (θr + T) of the nth-order diffracted light are normal (vertical axis) Ax1 to the surface of the wafer 5 (the wafer 5 can be regarded as a flat plate). Therefore, the normal direction of the wafer mounting surface of the holder portion 41 and the normal surface of the wafer surface can be regarded as the same), and the angle direction seen on the incident side is plus, and the angle direction seen on the opposite side is minus. With respect to the diffraction order n, the angle direction expected on the incident side with respect to 0th order light (regular reflection light) of n = 0 is plus, and the angle direction expected on the opposite side is minus. When the tilt angle T is changed, the incident angle (θi−T) and the outgoing angle (θr + T) change. For example, the tilt angle T is set to 0 degrees when the holder mechanism 40 is in a horizontal state. The angle direction to the side is plus, and the angle direction to the emission side is minus. Here, when the tilt angle is 0 degree (reference state), the incident angle is θi, and the exit angle is θr.

  First, in order to perform inspection with a specular reflection image, an image signal of the surface of the wafer 5 captured by the CCD image sensor 31 is sent to the image processing inspection apparatus 35 with an incident angle (θi−T) = an exit angle (θr + T). It is done. In the image processing inspection apparatus 35, the image of the surface of the wafer 5 obtained from the image signal from the CCD image pickup device 31 and the image of the surface of the non-defective wafer (inspection reference image) stored in advance are aligned (corresponding pattern). After the positions of the two overlap each other), a comparative inspection is performed. The comparison inspection includes a pattern matching inspection, a defect inspection based on a difference image made up of a difference from an inspection reference image learned in advance, and the like. If the wafer 5 to be inspected has a film thickness unevenness, the interference color is different, so it is detected as a defect. If there is a defect such as an abnormal pattern shape or a scratch, the defect is detected as a light / dark difference. it can.

  Next, when the illumination light is irradiated from the illumination optical system 10 to the surface of the wafer 5 supported by the holder mechanism 40 in order to inspect the diffraction image, the diffracted light from the wafer 5 is collected by the condensing optical system 20. , The wavelength λ of the illumination light applied to the wafer 5, the incident angle θi of this illumination light, the exit angle θr from the wafer 5 to the condensing optical system 20, and the wafer It is necessary to perform surface inspection by setting the tilt angle T of 5 (holder mechanism 40) to satisfy the above-described conditional expression (1) with respect to the pitch p of the pattern formed on the surface of the wafer 5. is there. For example, a wafer 5 on which a pattern with a pattern pitch p = 330 nm is inspected with an illumination light having a wavelength λ = 365 nm as a diffraction image of the first-order diffracted light with an inspection apparatus having an incident angle θi = 30 degrees and an emission angle θr = 0 degrees. In this case, the tilt angle T of the wafer 5 (holder mechanism 40) is −19.9 degrees.

  In the inspection using diffracted light, the incident angle (θi−T) and the emission angle (θr + T) are set so as to satisfy the above-described conditional expression (1), but before and after the tilt angle that satisfies the conditional expression (1). Thus, for example, the amount of received light may be monitored by changing the tilt angle in increments of 0.1 degrees, and the tilt angle at which the light amount is maximum may be stored as the tilt angle at the time of diffraction inspection.

  In addition, since the diffraction image observes the diffracted light of the light which irradiates a pattern, the brightness | luminance of the image is influenced by the shape change of a pattern. For example, a pattern formed by exposing the coated resist under appropriate exposure conditions (dose (exposure amount), focus state, etc.) and undergoing an appropriate resist development process has a rectangular shape with a fine cross section, and diffracted light. Is generated most strongly. However, if the exposure conditions and development conditions are inappropriate (dose failure, focus failure, developer amount failure, development time failure, etc.), the line width of the pattern will not become thin or the cross section will not be a clean rectangle. As a result, the luminance (light quantity) of the diffracted light decreases.

  In the diffraction image inspection, the tilt angle is set as described above, and the image signal of the surface of the wafer 5 picked up by the CCD image pickup device 31 is sent to the image processing inspection device 35. In the image processing inspection apparatus 35, an inspection is performed based on the luminance of the surface image of the wafer 5 obtained from the image signal from the CCD image sensor 31. A plurality of chips (patterns) are regularly arranged on the surface of the wafer 5, and there is a portion called a street line between the chips. This street line portion is a portion used as a cutting allowance when the IC chip is cut out after completion, and no pattern is formed. Therefore, diffraction does not occur in this street line portion, and the diffraction image is dark. In other words, since each chip appears to be separated by street lines on the surface of the wafer 5, it is possible to compare the chip with the chip in the diffraction image. Specifically, the inspection of each chip can be performed by comparing the brightness of each chip of the obtained diffraction image. Here, the luminance comparison of each chip obtains the average luminance of all the chips, and it may be abnormal if the luminance of each chip has a luminance difference with respect to this average luminance from a predetermined threshold. Moreover, defect inspection is also possible based on the difference image displaying the difference from the inspection reference image learned in advance.

  Here, in the specular reflection inspection, if the incident angle (θi−T) = the outgoing angle (θr + T), a regular reflection image could be obtained without being affected by the pitch of the pattern. However, the condition for obtaining a diffraction image in the diffracted light inspection depends on the pattern pitch p and the wavelength λ of the illumination light. In other words, even if the test object has the same pattern pitch p, if the wavelength λ of the illumination light changes, the obtained diffraction image may not be obtained.

  In the surface inspection apparatus 1 of the present embodiment, as shown in FIG. 1, the wavelength of illumination light is adjusted by a wavelength selection filter 13 made of an interference filter or the like. As described above, conventionally, the h line (405 nm), i line (365 nm), etc., which are the emission line spectrum of mercury (see FIG. 3), are used. Since the width was sufficiently narrow, the wavelength λ of the illumination light did not substantially change even if the transmission wavelength range of the wavelength selection filter 13 changed somewhat (see FIG. 4). However, as shown in FIG. 3, for example, the illumination light used in the 248 nm wavelength band, which is used as the pattern line width is reduced, has a comparatively broad (broad) peak instead of the mercury emission line spectrum. When the transmission characteristic of the wavelength selection filter 13 changes, the wavelength of the illumination light also changes.

For example, the interference filter used as the wavelength selection filter 13 is made of titanium oxide (TiO ₂ ), silicon dioxide (SiO ₂ ), zircon (ZrO ₂ ), alumina (Al ₂ O ₃ ) on quartz glass as a base material. The thickness of the transmitted light is adjusted by the interference effect of the thin film by laminating a thin film of a dielectric material such as the above. When viewed microscopically, this dielectric thin film has a porous structure (a structure having a large number of pores) and takes in moisture in the air and has an apparent refractive index. In addition, each dielectric thin film layer functions as an optical thickness of n · d (n is a refractive index, d is a geometric film thickness), and therefore the optical thickness depends on the amount of moisture contained in the thin film. It will change.

  In the present embodiment, a strong light beam is emitted from the light source 11 such as an ultra-high pressure mercury lamp, and the wavelength selection filter 13 absorbs most of light having a wavelength other than the transmitted wavelength. For this reason, the wavelength selective filter 13 is activated and becomes very high in temperature. As a result, each dielectric thin film layer releases moisture, the refractive index is lowered, and the optical thin film layer becomes thin. As a result of the optical film thickness of each dielectric thin film being thinned, the transmission characteristics are shifted to the short wavelength side, affecting the diffraction image as described above, and if it is significant, the diffraction image cannot be obtained.

  Therefore, it is necessary to grasp the wavelength of the illumination light when performing the inspection, and in this embodiment, the wavelength is obtained from the diffraction angle using the reference modulation unit 50. That is, prior to the inspection, illumination light (illumination light in the 248 nm wavelength band) is irradiated onto the reference modulation unit 50, and the emission angle of the diffracted light generated at that time is obtained to confirm the wavelength of the illumination light. Hereinafter, the inspection apparatus and the inspection method of this embodiment for detecting the wavelength of the illumination light based on the diffracted light generated by the reference modulation unit 50 will be described.

  First, the reference modulation unit 50 in the first embodiment is shown in FIG. The reference modulation unit 50 according to the present embodiment includes a plurality of first reference diffraction gratings 51a to 51p in which a glass substrate is subjected to chromium plating and a reference pattern is provided at a predetermined interval by an etching process. It is arranged on the outer periphery of the holder part 41 that is fixedly supported. Further, in the first reference diffraction gratings 51a to 51p, the surface (surface) on which the reference pattern is formed and the surface of the wafer 5 (surface on which the circuit pattern is formed) supported by the holder portion 41 are substantially the same surface. It is arranged. In each of the first reference diffraction gratings 51a to 51p, the repetition pitch of the lines constituting the reference pattern formed on the surface is different, and the shape of the reference pattern is guaranteed with high accuracy. The first reference diffraction gratings 51a to 51p may be formed by applying a resist on a silicon wafer, exposing a reference pattern at a predetermined interval, and developing it.

  When the surface inspection of the wafer 5 is performed, the inspection can be performed if the entire surface of the wafer 5 is within the imaging range of the imaging device 30, but the imaging device 30 can also capture the outside of the wafer 5 with a margin. Yes. The reference modulation section 50 (first reference diffraction gratings 51a to 51p) is disposed on the outer periphery of the holder section 41, which is the margin, and the diffracted light from the surfaces of the first reference diffraction gratings 51a to 51p is also imaged. Detection is possible by 30 CCD image sensors 31.

  An inspection method using a diffraction image of the wafer 5 using the inspection apparatus 1 configured as described above will be described below with reference to the flowchart of FIG.

  First, the wafer 5 to be inspected is transferred onto the holder mechanism 40 (step S101), and the wafer 5 is aligned (step S102). The wafer 5 is transferred by the wafer transfer mechanism (not shown) as described above, and is mounted on the wafer mounting surface (upper surface) of the wafer table 42 moved upward by the table driving unit 43. After the wafer table 42 receives the wafer 5 from the wafer transfer mechanism, the table driving unit 43 rotates the wafer table 42 so that the pattern repetition direction on the surface of the wafer 5 matches the illumination light irradiation direction. The wafer 5 is positioned in the rotational direction, and the wafer table 42 is lowered. Thereby, the wafer 5 is fixedly supported on the wafer placement surface of the holder portion 41 in a state where the azimuth angle (rotation angle) is accurately positioned (aligned state).

  When the wafer 5 is fixedly supported by the holder portion 41, the illumination light is irradiated onto the surface of the wafer 5 and the first reference diffraction gratings 51a to 51b (step S103). The light from the light source 11 passes through the wavelength selection filter 13 and the ND filter 14 and is emitted from the fiber 16 to the illumination system concave mirror 17, and becomes a parallel light beam by the illumination system concave mirror 17 to the holder unit 41 (holder mechanism 40). Illumination light is irradiated to the surface of the supported wafer 5 and the surfaces of the first reference diffraction gratings 51 a to 51 p disposed on the outer periphery of the holder portion 41. At this time, the wavelength of the illumination light corresponding to the pitch of the circuit pattern to be inspected formed on the surface of the wafer 5 is set by the wavelength selection filter 13.

  Then, the holder mechanism 40 is tilted so that diffracted light (inspection light) of a desired order from the surface of the wafer 5 and the first reference diffraction gratings 51a to 51p is taken into the condensing optical system 20 (step S104). A desired order of diffracted light from the surfaces of the wafer 5 and the first reference diffraction gratings 51 a to 51 p is collected by the condensing concave mirror 21 and restricted by the diaphragm 22, and the CCD imaging element of the imaging device 30 by the imaging lens 23. The incident angle and the emission angle of the illumination light, that is, the tilt angle of the holder mechanism 40 (wafer 5) is set so as to form an image on the lens 31.

  When the tilt angle of the holder mechanism 40 is set, the wavelength of the illumination light is confirmed (detected) based on the diffracted light from the first reference diffraction gratings 51a to 51p (step S105). At this time, attention is paid to the reference diffraction grating having a pitch approximate to the circuit pattern to be inspected on the wafer 5 among the first reference diffraction gratings 51a to 51p, and diffracted light of a desired order (inspection) from the surface of the reference diffraction grating. The wavelength of the illumination light (actual wavelength) is detected based on the above equation (1) from the light emission angle, that is, the light receiving position of the diffracted light imaged on the CCD image pickup device 31 via the condensing optical system 20. Is done.

  Then, the tilt angle of the holder mechanism 40 is adjusted based on the detected wavelength of the illumination light (step S106), and a diffraction image of the surface of the wafer 5 is captured (step S107). When the wavelength of the detected illumination light is different from the wavelength of the illumination light set by the wavelength selection filter 13 in step S103 (when wavelength variation occurs), from the wavelength detected based on the above equation (1) The tilt angle of the holder mechanism 40 is reset. If no wavelength variation has occurred, the tilt angle of the holder mechanism 40 set in step S104 is maintained as it is. The diffracted light (inspection light) emitted from the wafer 5 forms an image on the CCD image pickup device 31 by the condensing optical system 20, generates an image signal of the image on the wafer surface, and outputs the image signal to the image processing inspection device 35 for control. The image is converted into a digital image by the unit 37 to generate an image of the wafer 5.

  When an image of the wafer 5 is generated by the image processing inspection device 35, the presence or absence of an abnormality (such as a defect) on the surface of the wafer 5 is inspected based on this image (step S108). At this time, if there is an abnormality in the shape of the periodic structure in the pattern on the surface of the wafer 5 (for example, the ratio of line to space, taper degree, edge roughness, etc.), the intensity of the received diffracted light changes. Therefore, for example, by comparing with image data of a non-defective wafer (pattern) stored in advance in the memory 36, it is possible to inspect whether there is an abnormality on the surface of the wafer 5. The inspection result and the image of the wafer 5 at that time are displayed on an image display device (not shown).

  As described above, the wavelength of the illumination light is confirmed (detected) based on the diffracted light from the first reference diffraction gratings 51a to 51p, and the tilt angle of the holder mechanism 40 (wafer 5) is determined based on the actual wavelength of the illumination light. By performing the inspection using the diffraction image after the adjustment, it is possible to perform an accurate inspection that is not affected by the wavelength variation. Moreover, since the shape of the reference pattern formed on the surface of the first reference diffraction gratings 51a to 51p is guaranteed with high accuracy, the standard is established by using the intensity of light from the first reference diffraction gratings 51a to 51p as a reference. Thus, there is no variation in inspection results among a plurality of inspection apparatuses, and it becomes possible to improve the process control accuracy of the semiconductor manufacturing process.

  Next, the reference modulation unit 50 in the second embodiment is shown in FIG. As in the first reference diffraction gratings 51a to 51p described above, the reference modulation unit 50 according to the present embodiment is formed by applying a chrome plating to a glass substrate and providing a reference pattern at a predetermined interval by etching, or by applying a resist to a silicon wafer. The second reference diffraction gratings 52a to 52j are formed by applying and developing a reference pattern at a predetermined interval. The second reference diffraction gratings 52a to 52j are disposed in the vicinity of the tilt axis Ax2 on the outer periphery of the holder portion 41 of the holder mechanism 40. The second reference diffraction gratings 52a to 52j also have a surface (surface) on which the reference pattern is formed and a surface of the wafer 5 (surface on which the circuit pattern is formed) supported by the holder portion 41 so as to be substantially the same surface. It is arranged.

  Each of the second reference diffraction gratings 52a to 52j is different from the reference diffraction gratings 51a to 51p described above in that the repetitive pitches of the lines constituting the reference pattern formed on the surface are different from each other. The shape is guaranteed with high accuracy. Further, the second reference diffraction gratings 52 a to 52 j are also provided when the wafer 5 of the holder unit 41 (holder mechanism 40) is supported and are disposed within the imaging range of the imaging device 30.

  Also in this embodiment, the inspection is performed on the diffraction image of the wafer 5 using the inspection apparatus 1 as in the first embodiment. Also in this case, first, the wafer 5 to be inspected is transferred onto the holder mechanism 40 and the wafer 5 is aligned. When the wafer 5 is fixedly supported by the holder portion 41 in an aligned state, illumination light is irradiated onto the wafer 5 and the surfaces of the second reference diffraction gratings 52a to 52j. Then, the incident angle and the emission angle of the illumination light, that is, the holder mechanism so that the desired order of diffracted light (inspection light) from the surfaces of the wafer 5 and the second reference diffraction gratings 52a to 52j is taken into the condensing optical system 20. The tilt angle of 40 (wafer 5) is set.

  Next, when the tilt angle of the holder mechanism 40 is set, the wavelength of the illumination light is confirmed (detected) based on the diffracted light from the second reference diffraction gratings 52a to 52j. At this time, attention is paid to the reference diffraction grating having a pitch approximate to the circuit pattern to be inspected on the wafer 5 among the second reference diffraction gratings 52a to 52j, and diffracted light of desired order (inspection) from the surface of the reference diffraction grating. The wavelength of the illumination light (the wavelength of the actual illumination light) based on the above equation (1) from the light emission angle, that is, the light receiving position of the diffracted light imaged on the CCD image pickup device 31 via the condensing optical system 20 ) Is detected. Then, the tilt angle of the holder mechanism 40 is adjusted based on the detected wavelength of the illumination light, and a diffraction image of the surface of the wafer 5 is captured. Based on the image of the wafer 5 obtained in this manner, for example, the abnormality of the surface of the wafer 5 is inspected by comparing with image data of a good wafer (pattern) stored in advance.

  As described above, in the second embodiment, the second reference diffraction gratings 52a to 52j are arranged near the tilt axis Ax2. As a result, for example, the diffraction conditions of the reference diffraction gratings 52x and 52x ′ disposed in the vicinity of the axis Ax3 orthogonal to the tilt axis Ax2 and the vertical axis Ax1 (hereinafter referred to as the orthogonal axis Ax3) are accidentally being inspected. If the condition for generating diffracted light entering the wafer image is satisfied, unnecessary light may enter the inspection image of the wafer 5. In the second embodiment, since the second reference diffraction gratings 52a to 52j are disposed in the vicinity of the tilt axis Ax2, there is no possibility that unintended regular reflection light or diffracted light enters the inspection image when the wafer 5 is inspected.

  Next, the reference modulation unit 50 in the third embodiment is shown in FIG. As in the first reference diffraction gratings 51a to 51p and the like described above, the reference modulation unit 50 of the present embodiment is formed by applying a chrome plating to a glass substrate and providing a reference pattern at a predetermined interval by an etching process, or on a silicon wafer. It comprises third reference diffraction gratings 53a to 53d which are coated with a resist, exposed with a reference pattern at a predetermined interval, and developed. The third reference diffraction gratings 53a to 53d are arranged on the outer periphery of the holder portion 41 of the holder mechanism 40 at symmetrical positions via the wafer 5 in the vicinity of the tilt axis Ax2 and in the vicinity of the orthogonal axis Ax3. Further, the third reference diffraction gratings 53a to 53d are also configured so that the surface (surface) on which the reference pattern is formed and the surface of the wafer 5 (surface on which the circuit pattern is formed) supported by the holder portion 41 are substantially the same surface. It is arranged. Further, the third reference diffraction gratings 53 a to 53 d are also provided when the wafer 5 of the holder portion 41 (holder mechanism 40) is supported and are disposed within the imaging range of the imaging device 30.

  A plurality of reference patterns (for example, 70 nm, 90 nm, and 150 nm pitch reference patterns) having different pitches are formed on the surface of each of the third reference diffraction gratings 53a to 53d. The shape is guaranteed with high accuracy. Note that similar reference patterns are formed on the surfaces of the third reference diffraction gratings 53a to 53d (that is, the third reference diffraction gratings 53a to 53d have similar diffraction characteristics).

  Also in the present embodiment, the inspection is performed on the diffraction image of the wafer 5 using the inspection apparatus 1 as in the first and second embodiments. This inspection method will be described below with reference to the flowchart of FIG. Also in this case, first, the wafer 5 to be inspected is transferred onto the holder mechanism 40 (step S301), and alignment of the wafer 5 is performed (step S302). When the wafer 5 is fixedly supported by the holder 41 in the aligned state, the illumination light is irradiated to the surface of the wafer 5 and the third reference diffraction gratings 53a to 53d (step S303). Then, the incident angle and the emission angle of the illumination light, that is, the holder mechanism, so that diffracted light (inspection light) of a desired order from the surface of the wafer 5 and the third reference diffraction gratings 53a to 53d is taken into the condensing optical system 20. The tilt angle of 40 (wafer 5) is set (step S304).

  Next, when the tilt angle of the holder mechanism 40 is set, in the third reference diffraction gratings 53a to 53d, a pitch approximate to the pattern to be inspected on the wafer 5 is set as in the first and second embodiments described above. Focusing on the portion of the reference pattern that has the above, from the emission angle of the desired order of diffracted light from the portion of the reference pattern, that is, from the light receiving position of the diffracted light that forms an image on the CCD image pickup device 31 via the condensing optical system 20 The wavelength of the illumination light (actual wavelength of the illumination light) is detected based on Equation (1). Then, the tilt angle of the holder mechanism 40 is adjusted based on the detected wavelength of illumination light (step S305), and a diffraction image of the surface of the wafer 5 is captured (step S306). Then, based on the obtained image of the wafer 5, for example, an abnormal inspection on the surface of the wafer 5 is performed by comparing with image data of a good wafer (pattern) stored in advance (step S 307).

  As described above, the inspection by the diffraction image is performed after the tilt angle of the holder mechanism 40 (wafer 5) is adjusted based on the actual wavelength of the illumination light. In order to increase the throughput (number of inspections per hour), such tilt angle adjustment is usually performed once for a plurality of wafers in one lot (25 sheets), and inspection of a plurality of wafers is performed with the adjusted tilt angle. It is carried out. In such an inspection, a normal wafer image may not be obtained in step S306 while a plurality of wafers are inspected. That is, there is a case where luminance deterioration exceeding a predetermined reference range may occur as compared with a wafer image (or a non-defective wafer image) obtained so far. In this case, for example, a tilt angle shift due to a mechanical failure of the tilt drive mechanism (not shown), an azimuth angle shift (alignment failure) about the vertical axis Ax1 of the wafer 5 supported by the holder unit 41, The illumination optical system 10, the condensing optical system 20, or the image pickup device 30 (light receiving sensitivity of the CCD image pickup device 31) may have some problem (abnormality).

  First, the third reference diffraction gratings 53a and 53c disposed in the vicinity of the orthogonal axis Ax3 or the pattern to be inspected on the side of the wafer 5 in the direction of the orthogonal axis Ax3, and 53b and 53d or the wafer disposed in the vicinity of the tilt axis Ax2 Focusing on the pattern to be inspected in the vicinity of the tilt axis Ax2 of 5 (the central portion of the wafer 5), the inspection light (diffracted light or reflected light) from these has a luminance difference exceeding a predetermined reference range (for example, 5 % Brightness degradation), it is determined (detected) as a tilt angle shift due to a mechanical malfunction of the tilt drive mechanism or the like. Then, the tilt angle deviation of the holder mechanism 40 is adjusted based on the detected luminance difference of the inspection light (step S308).

  Actually, as shown in FIG. 10, when a tilt angle deviation of about 0.16 degrees or more in the ± direction occurs, a luminance deterioration of 5% or more occurs as compared with the case where there is no deviation of the tilt angle, In the wafer image, bright portions and dark portions are generated in the direction of the orthogonal axis Ax3 (vertical direction in the drawing). Specifically, when a tilt angle shift of about 0.16 degrees or more occurs in the + direction, the center tilt axis Ax2 direction (left and right direction in the drawing) of the wafer image becomes dark. Further, when a tilt angle deviation of about 0.16 degrees or more occurs in the negative direction, the side portion of the wafer image in the direction of the orthogonal axis Ax3 becomes dark.

  Further, paying attention to the third reference diffraction gratings 53a to 52d and the vicinity of the orthogonal axis Ax3 of the wafer 5 (the central part of the wafer 5) or the side part of the wafer 5 in the tilt axis Ax2 direction, the inspection light (diffracted light) from these Alternatively, when the reflected light) has a luminance difference exceeding a predetermined reference range (for example, when a luminance deterioration of 5% occurs), the azimuth angle (rotation angle) of the wafer 5 by the table driving unit 43 or the like (alignment) (Defect). Then, the orientation angle deviation of the wafer 5 is adjusted based on the detected luminance difference of the inspection light (step S309).

  Actually, as shown in FIG. 11, when an azimuth angle (rotation angle) deviation of about 4 minutes or more occurs in the ± direction, a luminance deterioration of 5% or more occurs as compared with the case where there is no azimuth angle deviation. In the wafer image, a bright portion and a dark portion are generated in the tilt axis Ax2 direction (left and right direction in the drawing). Specifically, when the azimuth angle deviation of about 4 minutes or more occurs in the + direction, the direction of the center orthogonal axis Ax3 (up and down direction in the drawing) of the wafer image becomes dark. Further, when the azimuth angle shift of about 4 minutes or more occurs in the negative direction, the side portion of the wafer image in the direction of the tilt axis Ax2 becomes dark.

  Further, paying attention to the third reference diffraction gratings 53a to 52d, when the luminance of the inspection light (diffracted light or reflected light) therefrom deviates from the predetermined reference range to the same extent, the illumination optical system 10, It is determined (detected) that the optical optical system 20 or the imaging device 30 (the light receiving sensitivity of the CCD imaging device 31) has some trouble (abnormality). Then, the malfunction of the illumination optical system 10, the condensing optical system 20, or the imaging device 30 is adjusted (or replaced) based on the detected luminance of the inspection light (step S310).

  Then, based on the brightness of each inspection light, the tilt angle deviation of the holder mechanism 40, the azimuth angle deviation of the wafer 5 (holder mechanism 40), the illumination optical system 10, the condensing optical system 20, and the imaging device 30 are adjusted. After that, the diffraction image of the surface of the wafer 5 is picked up again, and based on the obtained image of the wafer 5, the abnormality on the surface of the wafer 5 is inspected in step S307.

  As described above, in the third embodiment, the third reference diffraction gratings 53a to 52d disposed in the vicinity of the tilt axis Ax2 and the orthogonal axis Ax3, and the inspection light (diffracted light or reflected light) from the surface of the wafer 5 are used. ), It is possible to detect not only the wavelength variation of the illumination light, but also mechanical defects such as the tilt drive mechanism and the table drive unit 43, the alignment defect of the wafer 5, etc., and these can be adjusted for accurate inspection. It becomes possible.

According to the inspection apparatus 1 configured as described above and the inspection method using the inspection apparatus 1,
Based on the diffracted light from the wafer 5 and the reference modulation unit 50, the wavelength of the illumination light, the tilt angle of the holder mechanism 40 (wafer 5) (the incident angle and the emission angle of the illumination light), and the wafer 5 supported by the holder unit 41 The inspection state such as the azimuth angle (alignment state) is detected, and after adjusting these, the inspection by the diffraction image, the specular reflection image, etc. is performed. Accurate inspection that is not received is possible. In addition, since the shape of the reference pattern formed on the surface of the reference modulation unit 50 is guaranteed with high accuracy, it can be normalized by using the intensity of light from the reference modulation unit 50 as a reference, and between a plurality of inspection apparatuses. Thus, there is no variation in inspection results, and it becomes possible to improve the process control accuracy of the semiconductor manufacturing process.

  In the above-described embodiment, the reference modulation unit 50 is arranged and configured in the holder mechanism 40, but is not limited to this configuration, and the holder mechanism 40 as long as it is arranged within the imaging range of the imaging device 30. It does not need to be arranged in the. Further, although the CCD has been described as an example of the imaging device, a solid amplification type imaging device such as a CMOS may be used. In addition, it is possible to scan a test image using a line sensor in the imaging apparatus. It is also possible to divide and image the entire wafer to be inspected for inspection.

It is a figure showing the whole inspection device composition concerning the present invention. It is a figure which shows the structure of the holder mechanism in the said inspection apparatus. (A) It is a figure which shows the emission line spectrum of a mercury lamp, (b) is the figure which expanded a part of figure of (a). It is the figure which showed the transmission wavelength range of the wavelength selection filter. It is a figure which shows the structure of the 1st reference modulation part which concerns on this invention, (a) is a top view of a reference modulation part and a holder mechanism, (b) is sectional drawing in the tilt axis Ax2 shown to (a). . It is a 1st flowchart which shows the inspection method which concerns on this invention. It is a figure which shows the structure of the 2nd reference | standard modulation | alteration part based on this invention, (a) is a top view of a reference | standard modulation | alteration part and a holder mechanism, (b) is sectional drawing in the tilt axis Ax2 shown to (a). . It is a figure which shows the structure of the 3rd reference | standard modulation part which concerns on this invention, (a) is a top view of a reference | standard modulation part and a holder mechanism, (b) is sectional drawing in the tilt axis Ax2 shown to (a). . It is a 3rd flowchart which shows the inspection method which concerns on this invention. It is a figure explaining the correlation with a tilt angle shift | offset | difference and a wafer image. It is a figure explaining the correlation with an azimuth (rotation angle) shift | offset | difference and a wafer image.

Explanation of symbols

1 Inspection device 5 Wafer (test object)
DESCRIPTION OF SYMBOLS 10 Illumination optical system (irradiation part) 30 Imaging device (light-receiving part)
37 Control part (inspection state control part) 38 Inspection state detection part 39 Defect detection part (inspection part) 40 Holder mechanism (support part)
50 Reference modulation section (modulation section)
51a to 51p first reference diffraction grating (modulation unit)
52a to 52j Second reference diffraction grating (modulation unit)
53a to 53d Third reference diffraction grating (modulation unit)

Claims (27)

An irradiation unit for irradiating the inspection object with the irradiation light for inspection; and
A modulator that emits the inspection light that has been irradiated with the inspection irradiation light and that has generated a predetermined physical modulation according to the wavelength of the inspection irradiation light;
A light receiving unit that receives the inspection light emitted by receiving the physical modulation in the test object and the modulation unit under irradiation of the inspection irradiation light;
An inspection unit that inspects the inspection object based on inspection light that has been subjected to the physical modulation by the inspection object received by the light receiving unit;
An inspection state detection unit for detecting the state of the inspection,
The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit is arranged, and the inspection state detection unit detects the state of the inspection based on the inspection light subjected to the physical modulation by the modulation unit ,
An inspection apparatus comprising a plurality of the modulation units corresponding to the inspection irradiation lights having a plurality of different wavelengths . The inspection apparatus according to claim 1 , wherein the plurality of modulation units corresponding to the plurality of inspection irradiation lights having different wavelengths are arranged at a plurality of different positions. The inspection apparatus according to claim 1 , wherein the plurality of modulation units having the same physical modulation characteristics are provided at symmetrical positions via the test object. An irradiation unit for irradiating the inspection object with the irradiation light for inspection; and
A modulator that emits the inspection light that has been irradiated with the inspection irradiation light and that has generated a predetermined physical modulation according to the wavelength of the inspection irradiation light;
A light receiving unit that receives the inspection light emitted by receiving the physical modulation in the test object and the modulation unit under irradiation of the inspection irradiation light;
An inspection unit that inspects the inspection object based on inspection light that has been subjected to the physical modulation by the inspection object received by the light receiving unit;
An inspection state detection unit for detecting the state of the inspection,
The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit is arranged, and the inspection state detection unit detects the state of the inspection based on the inspection light subjected to the physical modulation by the modulation unit,
A plurality of said modulating portion having a property equivalent the physical modulation, the you characterized in that it comprises a symmetrical position via the specimen inspection apparatus. The inspection according to claim 4 , wherein the light receiving surface of the inspection irradiation light of the modulation unit and the light receiving surface of the inspection irradiation light of the test object are arranged substantially in the same plane. apparatus. The inspection apparatus according to claim 4 , further comprising a support unit that supports the test object, wherein the modulation unit is disposed in the vicinity of the support unit. The inspection apparatus according to claim 4 , further comprising a support unit that supports the test object, wherein the modulation unit is disposed on the support unit. The support portion tilts the test object, thereby causing an incident angle of the inspection irradiation light to the test object and a light receiving position of the test light that receives the physical modulation on the test object. is adjustable, said billing tilt axis of the object, characterized in that the said set in the light-receiving surface and the vicinity substantially flush or of identity a plane of the street the test object near the center of the object Item 8. The inspection device according to Item 6 or 7 .   The inspection apparatus according to claim 8, wherein the modulation unit is disposed in the vicinity of the tilt axis. The modulator is symmetric with respect to the test object near the tilt axis, and symmetric with respect to the test object in the vicinity of the orthogonal axis perpendicular to the tilt axis near the center of the test object. The inspection apparatus according to claim 8 , wherein the inspection apparatus is disposed in the area. The inspection apparatus according to claim 4 , wherein the inspection state detection unit detects the inspection state based on the preset physical modulation.   The inspection apparatus according to claim 11, wherein the inspection state detection unit detects the inspection state based on diffracted light or specular reflection light generated by the modulation unit. An irradiation unit for irradiating the inspection object with the irradiation light for inspection; and
A modulator that emits the inspection light that has been irradiated with the inspection irradiation light and that has generated a predetermined physical modulation according to the wavelength of the inspection irradiation light;
A light receiving unit that receives the inspection light emitted by receiving the physical modulation in the test object and the modulation unit under irradiation of the inspection irradiation light;
An inspection unit that inspects the inspection object based on inspection light that has been subjected to the physical modulation by the inspection object received by the light receiving unit;
An inspection state detection unit for detecting the state of the inspection,
The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit is arranged, and the inspection state detection unit detects the state of the inspection based on the inspection light subjected to the physical modulation by the modulation unit,
The inspection state detection unit is based on the inspection light subjected to the physical modulation by the modulation unit, the incident angle of the inspection irradiation light, the wavelength of the inspection irradiation light, the tilt angle of the test object, Detecting the inspection state of at least one of a light receiving position of the inspection light subjected to the physical modulation by the light receiving unit and an azimuth angle of the inspection object when the inspection object is rotated; It is that the inspection apparatus.   The inspection apparatus according to claim 13, wherein the inspection state detection unit detects a wavelength of the inspection irradiation light based on a light receiving position of the diffracted light generated in the modulation unit by the light receiving unit.   The inspection state detection unit is configured such that the physical modulation is performed at the modulation unit disposed in the vicinity of the orthogonal axis orthogonal to the tilt axis for tilting the test object and the modulation unit or at the side of the test object in the orthogonal axis direction. The difference in luminance between the inspection light subjected to the physical modulation and the inspection light subjected to the physical modulation by the modulation unit arranged near the tilt axis or the test object near the tilt axis exceeds a predetermined reference range. The inspection apparatus according to claim 13, wherein a defect in a tilt angle of the object to be detected is detected.   The inspection state detection unit includes the inspection light that has undergone the physical modulation by the modulation unit, and the test object or the tilt axis direction in the vicinity of an orthogonal axis that is orthogonal to a tilt axis that tilts the test object and the modulation unit. A defect in the azimuth angle of the test object is detected when the inspection light subjected to the physical modulation at the side of the test object has a luminance difference exceeding a predetermined reference range. The inspection apparatus according to claim 13.   The inspection state detection unit is configured to illuminate the illumination unit when the inspection light subjected to the physical modulation by the modulation units arranged at different positions deviates from a predetermined reference range to the same extent. The inspection apparatus according to claim 13, wherein a defect of at least one of a system and a light receiving optical system or light receiving sensitivity of the light receiving unit is detected. An irradiation unit for irradiating the inspection object with the irradiation light for inspection; and
A modulator that emits the inspection light that has been irradiated with the inspection irradiation light and that has generated a predetermined physical modulation according to the wavelength of the inspection irradiation light;
A light receiving unit that receives the inspection light emitted by receiving the physical modulation in the test object and the modulation unit under irradiation of the inspection irradiation light;
An inspection unit that inspects the inspection object based on inspection light that has been subjected to the physical modulation by the inspection object received by the light receiving unit;
An inspection state detection unit for detecting the state of the inspection,
The test object so that the inspection light that has undergone the physical modulation by the test object and the inspection light that has undergone the physical modulation by the modulation part are within a range that can be simultaneously received by the light receiving unit. The modulation unit is arranged, and the inspection state detection unit detects at least the wavelength of the inspection illumination light as the inspection state based on the inspection light subjected to the physical modulation in the modulation unit,
The check state detecting unit based on the wavelength detected by the Ru with a check state control unit to set or change the tilt angle of the object inspection apparatus you said. An inspection method for inspecting the test object based on the test light irradiated with test irradiation light on the test object and subjected to physical modulation in the test object,
The inspection irradiation light is applied to the test object and a modulation unit that receives the irradiation of the inspection irradiation light and generates the physical modulation preset in accordance with the wavelength of the inspection irradiation light in the inspection irradiation light. A first step of receiving inspection light emitted by receiving the physical modulation in the test object and the modulation unit;
Inspecting the inspection object based on the inspection light that has been subjected to the physical modulation by the inspection object received in the first step, and based on the inspection light that has been subjected to the physical modulation by the modulation unit And a second step of detecting the state of the inspection ,
In the first step, the inspection light having undergone the physical modulation is received by the plurality of modulation units corresponding to the irradiation light for inspection having a plurality of different wavelengths,
In the second step, the state of the inspection is detected based on the inspection light subjected to the physical modulation by the modulation unit corresponding to the inspection portion of the test object among the plurality of modulation units. Inspection method. In the first step, diffracted light or specularly reflected light generated in the test object and the modulation unit is received,
In the second step, the inspection object is inspected based on diffracted light or specular reflection light generated in the inspection object, and the inspection is performed on the basis of diffracted light or specular reflection light generated in the modulation unit. The inspection method according to claim 19 , wherein the state is detected. By tilting the test object, it is possible to adjust the incident angle of the inspection irradiation light to the test object and the light receiving position of the test light subjected to the physical modulation in the test object, The tilt axis of the test object passes through the vicinity of the center of the test object and is set substantially on the same plane as or near the same plane as the light receiving surface of the test irradiation light of the test object,
In the second step, based on the inspection light subjected to the physical modulation in the modulation unit, the incident angle of the inspection irradiation light, the wavelength of the inspection irradiation light, the tilt angle of the inspection object, receiving position of the physical modulating received inspection light, and the claims, characterized in that to detect at least a state of one of the inspection of the azimuth angle of the test object when rotating the test object 19 Or the inspection method of 20 . In the first step, diffracted light generated by the modulation unit is received;
The inspection method according to claim 21 , wherein in the second step, the wavelength of the inspection irradiation light is detected based on a light receiving position of the diffracted light received in the first step. In the second step, the physical modulation is performed at the modulation unit disposed near the orthogonal axis orthogonal to the tilt axis near the center of the test object or at the side of the test object in the orthogonal axis direction. The inspection light received and the inspection light subjected to the physical modulation by the modulation unit arranged near the tilt axis or the test object near the tilt axis have a luminance difference exceeding a predetermined reference range. The inspection method according to claim 21 , wherein a defect in a tilt angle of the test object is detected. In the second step, the inspection light that has undergone the physical modulation by the modulation unit and the test object in the vicinity of the orthogonal axis that is orthogonal to the tilt axis in the vicinity of the center of the test object or in the direction of the tilt axis A defect in the azimuth angle of the test object is detected when the inspection light subjected to the physical modulation at the side portion of the test object has a luminance difference exceeding a predetermined reference range. The inspection method according to claim 21 . In the second step, the illumination optical system of the irradiation unit when the inspection light that has undergone the physical modulation by the modulation units arranged at a plurality of different positions deviates from a predetermined reference range to the same extent. 21. The inspection method according to claim 19 or 20 , wherein a defect of at least one of the light receiving optical system and the light receiving sensitivity of the light receiving unit is detected. 26. The inspection method according to claim 19 , further comprising a third step of setting or changing the state of the inspection based on the state of the inspection detected in the second step. 27. The inspection method according to claim 26 , wherein, in the third step, a tilt angle of the test object is set or changed based on the wavelength detected in the second step.