JPS5994032A - Apparatus for measuring characteristics of image forming optical system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring optical characteristics of an imaging optical system, and in particular to a measuring device suitable for a projection optical system of an apparatus that projects and exposes a mask pattern of an integrated circuit onto a semiconductor substrate. It is related to.

The miniaturization of large-scale integrated circuit (LSI) patterns is progressing year by year, and reduction projection exposure apparatuses have become popular as devices for printing circuit patterns that meet the demands for miniaturization and have high productivity. In these conventionally used devices, a reticle pattern that is twice as large (for example, 10 times) as the pattern to be printed on a silicon wafer (hereinafter referred to as a wafer) is reduced and projected by a projection lens, What is printed by exposure is an area smaller than a square with a diagonal length of 14 mm on the wafer.

Therefore, in order to print a pattern on the entire surface of a wafer having a diameter of about 125 mm, a so-called step-and-repeat method is used, in which the wafer is placed on a stage, moved a certain distance, and exposed repeatedly.

In LSI manufacturing, patterns of several layers or more are sequentially formed on a wafer, but unless the overlay error of patterns between different layers is kept below a certain value, the conductive or insulating state between the layers may not match the intended state. Therefore, it becomes impossible to perform the functions of the LSI. For example, for a circuit with a minimum line width of 1 μm, only an overlay error of about 0.2 μm is allowed at most. Among the causes of this overlay error, those generated by the exposure apparatus are (1) projection magnification error and projection distortion, and (2) relative positional deviation between the projected image and the wafer. The distortion caused by the above (1) is the distortion aberration of the projection optical system. On the other hand, the magnification error can be reduced by changing the distance between the reticle and the principal point (principal plane) of the projection optical system if the reticle-side light beam of the projection optical system is not telecentric; are the internal components of the projection optical system (
This can be made smaller by relatively shifting the position of optical members (such as lenses) in the optical axis direction. Therefore, if the distance between the reticle and the projection lens and the relative positions of the components inside the projection lens do not change, the error due to one factor (1) is constant and can be said to be a systematic error. On the other hand, errors due to cause (2) include many random error factors, and are the main cause of variations in vehicle alignment errors each time alignment is performed.

Now, the error in (1), which is a systematic error, is
If you adjust the equipment so that the value is below a certain value while measuring the compensation, you can maintain a stable small value over a long period of time.
It must be kept as small as possible. From before (1
) To measure the error, the image of a so-called test reticle, which has mark patterns drawn at multiple predetermined positions, is printed onto the photoresist on the wafer, and the coordinates of the resist image of the printed marks are measured. However, this was done by comparing the measured coordinates with the mark coordinates on the reticle. However, according to this method, the test
The reticle pattern is bright, and it takes time and effort to develop it, and the mark resist IJ#! The drawback was that expensive measuring equipment had to be used to measure gold.

SUMMARY OF THE INVENTION An object of the present invention is to solve these drawbacks and provide a measuring device that can easily measure optical characteristics such as projection magnification and projection distortion.

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a schematic diagram of a projection type exposure apparatus to which an embodiment of the present invention is applied.

Illumination light from an exposure illumination light source 1 is once converged by a first condenser lens 2 and then reaches a second condenser lens 3. In the optical path, a shutter 4 for blocking and passing illumination light is provided at a position where the light is converged. The light beam passing through the second condenser lens 3 illuminates a test reticle 5 (hereinafter simply referred to as reticle 5) as a mask. Light-transmissive marks M are placed on the lower surface of the reticle 5 at a plurality of predetermined positions.
u~M1. is depicted. Mark M on this reticle 5
The light beam 11 that has passed through I, .about.M11 is incident on a projection lens 6 as an imaging optical system whose optical characteristics are to be measured.

This projection lens 6 is a reticle s (111, that is, the object side is a non-telecentric optical system, and the image force is a telecentric optical system. The light beam tl is focused by the projection lens 6 and becomes a light beam t1, which is projected at body size. Similarly, the distance between the lower surface of the reticle 5 and the main plane 6a of the projection lens 6 is L.
shall be. The light beam t is imaged on a fine/J% aperture 8 provided on a two-dimensionally movable stage 7. Further, the light passing through 58 minute apertures 8 is photoelectrically converted by a photoelectric detector 9 provided on the stage 7Vt. That's a slur.
Usually, the wafer 10 is moved two-dimensionally by placing the semiconductor wafer 10 thereon, and the wafer 10 is moved together with the stage 7.
It is placed on a wafer holder 11 that moves dimensionally. The Ueno H holder 11 is provided so as to be able to perform minute rotation and vertical power with respect to the stage 7. This Ueno Horri 1
1, the projection lens 60 moves up and down so that the projected image is formed on the surface of the Ueno film 100, that is, so that focusing can be performed. Further, the υ1 opening surface on which the minute opening 8 is provided is determined to almost match the height of the surface of the wafer 100,
This aperture surface and the photoelectric detector 9 are provided so as to move up and down together as the ueno holder 11 moves up and down.

For this focusing, the projection lens 6 and the Ueno S10
A gear tooth sensor 12 is provided to measure the distance from the surface (or the opening surface of the copy opening 8). This gear rough "automatic thermal haR localization force 1" is achieved by the vertical movement of the sensor 12 and the wafer holder 11, and when printing a circuit pattern on the wafer 10, it detects the height of the surface of the wafer 10, Projected images with high contrast can always be transferred.

On the other hand, the position of the stage 7 is determined by using a laser interferometer 13 to measure the distance to a reflecting mirror 14 fixed to the stage 7 using a laser beam.

Although FIG. 1 only shows the X-axis direction in the left-right direction in the paper, it is perpendicular to the X-axis that forms the movement plane of the stage 7 (
Similarly, a laser interferometer and a reflecting mirror are provided in the y-axis direction (perpendicular to the plane of the paper).

These laser interferometers successively measure the coordinate values of the stage 7 with respect to a predetermined origin.

Similarly, the intersection of the two measurement axes formed by the respective laser beams of the laser interferometer in the X-axis and y-axis directions is determined to coincide with the optical axis of the projection lens 60.

Further, the reticle holder 15 holds the reticle 5 and
It is dimensionally movable and is driven and controlled by a reticle alignment control system, which will be described later, to position the reticle 5.

Now, FIG. 2 is a plan view of the reticle 5 shown in FIG. 1. The reticle 5 is constructed by depositing a chromium layer or a low-reflection chromium layer over the entire bottom surface of a glass substrate, as shown by the shaded area in the figure. In the chromium layer, cross marks as marks M through which light passes are formed in a 6×6 square matrix. It is assumed that the center positions of these cross marks have been previously measured by another measuring device in the coordinate system o-xy on the reticle 5 with an error of about 0.1 μm or less. The center positions of the cross marks are determined to be line symmetrical with respect to the coordinate axes X and Y, respectively, and point symmetrical with respect to the origin O, which is the center of the reticle 5. Similarly, in order to identify these cross marks, marks on the top row of the reticle 5 -tM, , M, ,...
... Ml, binding, mark in the row below it MH, Ff'
The first order is determined to be lH, . . . MH.

Therefore, the cross mark on the reticle 5 is generally specified by MiJ (however, i and j are 1 to 6), and the center position of the cross mark is specified by PiJ (however, isJ
are 1 to 6).

Further, FIG. 83 is a plan view of a light shielding part forming a minute opening 8 provided in the stage 7, and a cross-sectional view taken along the line A--A. The minute opening 8 is obtained by depositing a chromium layer 21 on a glass plate 20 to a thickness of about 0.1 μm, and forming two slit openings 8a and 8b in a part of the chromium layer 21. This chromium layer 21
The thickness of the projection lens 6 is sufficiently thinner than the depth of focus (several μm) of the projection lens 6. Now, the extending directions of the slit openings 8a and 8b are determined to be perpendicular to each other, and are determined to coincide with the moving direction xy of the stage 7, respectively. Similarly, the slit opening 8a, which is elongated along the y-axis direction, is used to detect the position in the X direction of the projected image of the projected cross mark Mij, and the slit opening 8b, which is elongated along the Xs direction, is used to detect the position of the projected image of the cross mark Mij. is used to detect the position of the projected image of the cross mark Mij in the X direction.

Further, the width of the slit openings 8a, 8b is set smaller than the width of the straight line portion of the projected image of the cross mark Mij. This will be explained in detail later.

Of course, the light receiving surface of the photoelectric detector 9 is located below the glass plate 20.

Next, the control system for controlling the device shown in Figure 1 is as follows.
This will be explained based on the block diagram of FIG.

The entire device is equipped with a microcomputer (including memory, etc.) to enable program control and six types of arithmetic processing.
It is centrally controlled by the following CPU (CPU) 30.

The CPU 30 exchanges various information with surrounding detection units, measurement units, or drive units via an interface 31 (hereinafter referred to as IF 51).

Now, the shutter drive unit 32 opens and closes the shutter 4 according to instructions from the CPU 30, and the reticle alignment control system 33 (hereinafter referred to as R-ALG 33) keeps the reticle 5 at a predetermined position with respect to the optical axis of the projection lens 6. The reticle holder 15 is moved and aligned so that the reticle holder 15 is aligned. Although this [(-ALG 33) is not necessarily necessary in the embodiments of the present invention, it is possible to align the reticle 5 more accurately and faster than by visual manual operation using alignment marks on the reticle 5. , In this device, the following 1 is also provided with -ALG33.

On the other hand, in order to measure the coordinates of the stage 7, the positional information of the stage 7 in the X direction read by the laser interferometer 13 and the positional information of the stage 7 in the X direction read by the laser interferometer 34 are Both, CPU3 via IF31
Sent to 0. In addition, in order to move the stage 7 two-dimensionally, the stage 7 is driven in the X direction.
5 (hereinafter referred to as X-ACT35) and stage 7
y#I drive unit 36 (hereinafter referred to as Y-ACT36) that drives in the direction
) is provided to operate according to instructions from the CPU 30.

In addition, a θ-axis rotation drive unit 37 (hereinafter θ-AC'l'37) for slightly rotating the wafer holder 11 on the stage 7 is provided.
), and a Z-axis moving section 38 (hereinafter referred to as Z
- AC'l' 38) is provided and operates according to instructions from the CPU 30. The focus detection unit 39 (hereinafter referred to as AIi''D39) inputs the signal from the cap sensor 12 shown in FIG. Focus position shift information is output to the CPU 30 via the IF 51.

Further, a terminal device 40 such as a monitor (111'', fi, printer, etc.) for displaying measurement results and operational conditions is also connected to the Cf'U 30 via 11i''31'.

In addition to the various control systems mentioned above, an actual exposure apparatus also includes a wafer alignment control system for positioning the wafer 10 in the x and y movement directions of the stage 7, but this is not directly related to the present invention and will not be explained here. is omitted.

Next, the operation of measuring the optical characteristics of the projection lens 6 using the exposure apparatus described above will be explained.

At the beginning of Ashizu, place the reticle 5 set on the device at 几-AL.
Position using G33. At this time, the projection lens 60
The optical axis is aligned so that it passes through the origin 0 of the coordinate system o-xy on the reticle 5. Furthermore, X, Y of the coordinate system 0-XY
The reticle 5 is positioned so that its axes are parallel to the x and y movement directions of the stage 7, that is, the measurement axes x and y of the laser interferometer 13.34, respectively (including the case where they are moved). As a result, the extension directions of the two orthogonal straight line portions of the cross mark Mij coincide with the xy movement directions of the stage 7, respectively.

Next, the stage 7 is moved by the X-AC'r 35 and the Y-ACT 36, and the height of the opening surface of the minute aperture 8, that is, the height of the surface of the chromium layer 210 in FIG.
2 and the AFD 39, and based on the detected information, the Z-AC'r 38 is driven so that the front surface of the chromium layer 21 coincides with the front surface of the chromium layer 21.

Next, the shutter drive unit 32 opens the shutter 4 to illuminate the reticle 5 and project the cross mark MIjO image onto the chrome layer 21. The positional relationship between the image of the cross mark MiJ and each slit opening 8a, 8b is, for example, the fifth
As shown in the diagram, X, -ACT35°Y-A,C
Actuate T36 to move stage 7.

At that time, when the slit openings 8a and 8b are located on the optical axis of the projection lens 60, the laser interferometer 13°14
Once the coordinate values have been determined, the approximate position of each cross mark ■ij can be easily determined using the coordinate values as the reference position.

At this time, the relationship between the sharpness of the projected cross mark MijO image and the sizes of the slit openings 8a and 8b as the minute openings 8 is as shown in FIG. In other words, the cross mark Mi
Of the image of j, the straight part extending in the X direction is the slit image L
x, and a straight line portion extending in the X direction perpendicular to the slit image Lx is defined as a slit image Ly. Then, the center of each slit image Lx, LyO width is the center line CL x
, CLy, and the intersection of the center lines CLx and CLy, that is, the center of the cross mark MIjO image, is the center CP. Further, the width of the slit openings 8a and 8b in the chromium layer 21 is determined so that d<D<h, where d1 is the length and h is the width.

Now, when the stage 7 is moved at a constant speed in the X direction from the position shown in FIG. 5 and scanned by the slit image Lx'r slit aperture 8a, the photoelectric detector 9 is detected as shown in FIG. 6(a).
Outputs a photoelectric signal such as ■. In FIG. 6(a), the horizontal axis represents the position of the stage 7 in the X direction, and the vertical axis represents the photoelectric signal
It is equivalent to the light intensity distribution in the width direction of the slit image LxO.

Therefore, the photoelectric signal ■ is compared with a predetermined reference level Ir, and the position x3. is taken into the CPU 30,
The two positions are averaged to find the position X. That is, the CPU 30 determines the position X of the stage 7 determined by the (x++x*)J operation as the projected position of the center line CLx of the slit image Lx.

On the other hand, regarding the slit image Ly, the stage 7 is moved in the X direction from the position shown in FIG.
is scanned and from the light intensity distribution, the position y of the stage 7 in the X direction is determined.
ak slip) 1#Ly is determined as the projected position of the center line CLY.

As a result, the coordinate values (x, ye) of the stage 7 are measured as the projected position of the center CP of the cross mark MijO image, and are stored in the CPU 30.

Similarly, the images of other cross marks are also measured, and the measured values are sequentially stored in correspondence with the position Pij of the cross mark Mij on the reticle 5.

Similarly, the size of the slit apertures 8a, F3b and the image of the cross mark Mij is set to d(D(h), because when detecting the projection position in the This is to enable position detection even if the slit aperture 8a scans the slit image Lx and the slit aperture 8b scans the slit image Lx at the same time.

For example, when the stage 7 is scanned in the X direction from a state where the slit opening 8a intersects with the slit image Ly, the photoelectric signal of the photoelectric detector 9 is as shown in FIG.
The maximum value I with a constant offset) Iof in the scanning part of
It becomes a signal of p. The size of this offset (Tof) is
The maximum value Ip is proportional to the area determined by the width d of the slit opening 8a and the width of the slit image Ly.
It is proportional to the area determined by the width d and length h of a.

In order to find the position X of the center line CLx of the slit image Lx by comparing such a signal with the reference level Ir, ■r)
Must be Iof. Therefore, the width of the slit image Ly and the length h of the slit opening 8a are set to D(h) in order to satisfy this condition. Also, the slit images Lx, L
Slit opening 8a with respect to the width of y.

The reason why the width d of 8b is made smaller is to make the rise and fall of the photoelectric signal steeper, and for this reason, it is determined as d(D).The relationship between the width d and D is as follows. Even if d=1), there is no substantial shadow change in photoelectric detection/position detection, and as in the above example, the cross mark MijO
The center position of the image is found.

Next, CPtJ30 checks each of the measured cross marks M.
Based on the projection position of the image ij and the position 1tPij, the optical characteristics of the projection lens 60 such as the projection magnification and the amount of distortion are calculated.

Same, each cross mark M measured as the position of stage 7
iJO image projection position f! 1Tij, Pij is expressed by coordinate values (Xij, Yij), and Tij is expressed by coordinate values (xij, yi''). So the projection magnification N? The following equation is used as an example of a calculation equation.

In this equation (1), the X origin and the X outlet are the cross marks Mll, M, , , M, , , , which form the leftmost row in Fig. 2.
The positions of M and l on the reticle 5 in the X direction and their 6
The projection positions of the cross marks in the X direction are respectively represented.

Then, Xia and
The position in the X direction above and the X of the six cross marks
and the projection position in the direction. Furthermore, the formula (1
), Ylj and ylj are the reticle 5 of the cross marks Mll, Mll, . . . Ml, which form the top row in FIG.
Y6j and yaj represent the upper Y-direction position and the projected position of the six marks in the X-direction, respectively, and Y6j and yaj represent the Y-direction positions of the cross marks Ms+, Ma,...Nagi in the bottom row, and their The projection positions of the six marks in the y direction are respectively represented.

Further, if the projection magnification to be set at the time of manufacturing or fine adjustment of the projection lens 6 is No, the error ("Lβij) of the position and reference including the distortion aberration of the image of the projected cross mark is α1j=xij- Xij/N.

βi j = y i j - Yi j /N.

becomes. However, at this time, it is assumed that the origin 0 of the coordinate system of the reticle 5 and the origin of the coordinate system of the projected image of the reticle 5 (that is, the origin of the coordinate values of the stage 7) are matched by appropriate calculation. This error (α'Lβij) represents the amount of projection distortion. The above calculated results are displayed on the terminal device 4.
Displayed by 0.

Although the projection magnification and the projection distortion can be obtained as described above, the equation (1) is just an example, and depending on the definition of the magnification, a calculation formula according to the definition may be used. For example, the cross marks Mu, Mu, MU.

Only the four corner marks of M@ may be used.

And if the calculated projection magnification exceeds the tolerance,
The main plane 6a of the reticle 5 and projection lens 6 shown in FIG.
The focal length can be changed by readjusting the distance between the projection lens 6 and the projection lens 6, or by readjusting the distance between the optical components (lenses) that make up the projection lens 6. Then, the magnification is measured again using the method described above, and the adjustment and measurement of the projection lens 6 are repeated until the magnification error becomes an acceptable value. Furthermore, when measuring the magnification error, the distortion aberration of the projection optical system is also measured to confirm that the aberration is tolerable. If the distortion exceeds the allowable amount, the position of the optical element inside the projection lens 6 is adjusted or the optical element is replaced with another one.

As described above, according to this embodiment, the time and effort of exposing and developing the test reticle pattern and measuring the resist image with other measuring equipment as in the conventional method can be omitted, and the projection The optical characteristics of the projection lens 6 can be measured very easily by simply providing a photoelectric detector 9 for detecting mark images on a moving stage that is normally provided in a mold exposure apparatus. In addition, not only when manufacturing exposure equipment, but also when replacing the projection lens 6 with a projection lens with a different reduction ratio at the LSI manufacturing site, no other special measuring equipment is required. Another advantage is that adjustments to optimize optical characteristics can be made extremely efficiently.

In the above embodiment, the optical characteristics were calculated by the CPU 30 built into the exposure apparatus, but after only the detected position of the projected image of each cross mark Mij is displayed on the terminal device 40, the information on the detected position is A similar effect can be obtained even if a predetermined calculation is performed using another calculator based on the calculation result.

In the above embodiment, the case where the image formation position coincides with the surface of the chromium layer 21, that is, the opening surface has been described. In this embodiment, the gap sensor 1 shown in FIG.
2 is attached, so if the gap sensor 12 is adjusted so that there is no detection error, this can be used, and the AFD 39 can detect the focus error with respect to the aperture plane and perform focusing.

However, in a configuration in which automatic focus detection is performed using a gap sensor, when the device is manufactured or when the projection lens is replaced, the detection signal of API) 39 generally has an offset with respect to focus detection. Therefore, relying only on the gap sensor makes it impossible to accurately match the imaging plane of the projected image with the aperture plane.

Therefore, as another embodiment of the present invention, a case where focus is detected from the contrast of a mark image projected using the photoelectric detector 9 will be described.

In this case, by utilizing the fact that the micro aperture 8 and the photoelectric detector 9 are simultaneously moved up and down by the wafer up and down movement mechanism Z-ACT 38, the length of the focal depth of the projection lens 6 is divided into several equal parts. The operation of moving the minute aperture 8 in the vertical direction by the same amount, scanning the stage 7, and measuring the intensity distribution of the image is repeated. Then, a focus state in which the width of the rise or fall in the image intensity distribution is minimized is determined. Actually, the intensity distribution of the projected image of the cross mark on the reticle 5 is examined.

Figure 7 shows the magnitude of the signal obtained by photoelectrically exchanging the image of the mark transmitted through the minute aperture 8 when the stage 7 is moved.The vertical axis represents the signal magnitude, and the horizontal axis represents the X The direction and position are clear. When the aperture surface with the slit aperture 8a and the image surface are close to each other, the photoelectric signal 1. The waveform of
Assuming that the image is obtained as shown in the figure, when the aperture plane and the image plane are further apart from each other than in this state, the width of the waveform becomes wider, and the signal becomes as shown in (2).

Therefore, the best focus state can be found by measuring the amount of waveform spread or the slope of the waveform shoulder and searching for the state where the amount of waveform spread is the minimum or the slope of the waveform shoulder is maximum. . An example of a specific method will be explained next. As shown in FIG. 7, two reference levels r, , r, are provided. Reference level r8. The magnitude of these is set to be a constant ratio to the maximum value of the photoelectric signal. Then, the stage 7 is scanned to find points p+ and p where the signal 1 coincides with these levels r, , rs.

is detected, and the waveform spread a te is measured from the distance in the X direction between the p8 point and the 91 point. This distance in the X direction is measured using a laser interferometer 13 that measures the stage position.
Calculate and perform with PU30. Similarly, signal I.

The position of the point p, , pa where the level coincides with the level r, , r, is detected, and the amount of spread e of the waveform is measured. FIG. 8 is a graph in which the horizontal axis represents the vertical position Z of the aperture surface due to the Z-ACT 38, and the vertical axis represents the spread amount e of the waveform of the photoelectric signal. When the aperture surface is moved vertically by a fixed amount, for example, 0.5 μm, and then stopped, the stage is scanned, and the entire amount of spread of the waveform shown in FIG. 7 is measured.
The spread amount e with respect to the position Z is stored in the memory of the CPU 30 as such data. In the figure, the amount of expansion e indicates the position Z where the aperture plane coincides with the image plane, and at positions Z, , Z, where the aperture plane is deviated from there, the amount of expansion is e, , e as explained in FIG. , becomes. To actually focus, position ZI, ZI...2. . . . The spread: te is measured and stored in order, and the Z-ACT 38 is driven so as to return to the position Z0 where the amount of spread is the minimum.

By the method exemplified above, the projection image plane of the projection lens 6 and the aperture plane of the minute aperture 8 can be made to coincide with each other.
The coordinates of the image can be measured while in focus.

As mentioned above, in this embodiment, since the projected image itself is detected by the photoelectric detector 9 provided on the stage 7, the signal has a high 87N ratio of 75, making it possible to accurately detect the focal position. Become. Therefore, the height of the aperture surface when the contrast of the projected image is maximized is detected by the gap sensor 12 shown in FIG. If the calibration is performed so that the detection offset is canceled, a clear pattern can always be transferred onto the film 10 without requiring any effort λ to adjust or replace the projection lens 6.

In addition, by checking the focus position me at each position within the effective exposure area of the projection lens 6 using a plurality of cross marks on the reticle 5 shown in FIG. Minute unevenness distribution, depth of focus distribution, etc. can be measured immediately. Therefore, from the measurement data, it is also possible to confirm the inclination of the optical axis of the projection lens 6 with respect to the moving plane (xy coordinate system) of the stage 7.

Now, in each of the above embodiments, the mark on the reticle 5 is not limited to a cross mark, but may also be a mark formed in an L-shape like the slit openings 8a and 8b.

Furthermore, the arrangement of the marks is not limited to the square matrix, and a plurality of marks may be arranged radially from the center of the reticle 5.

Further, although the micro-aperture 8 is made up of two slit apertures ga and 8b, the two slits may be integrated into an L-shaped micro-aperture. In this case as well, the relationship between the sizes of the L-shaped slit opening and the projected image of the cross mark is preferably set to d(D(h) as described above.

Furthermore, if the reticle holder 15 shown in FIG. 1 is made vertically movable in the direction of the optical axis of the projection lens 60, the projection lens 6 does not have to be moved vertically when adjusting the magnification, and the mechanical configuration is simplified. Become.

As described above, according to the present invention, it is possible to quickly and accurately measure the projection magnification and projection distortion of the projection optical system, and it is also possible to quickly and easily measure the projection magnification and projection distortion even when the measurement is performed at an exposure location. This has the advantage that the time adjustment can be completed quickly.

Furthermore, in cases where there is concern about the projection performance, such as after the exposure apparatus has been transported or after a strong impact has been applied to the exposure apparatus by mistake, the present invention makes it possible to easily check the projection performance.

Further, the present invention can be applied not only during manufacturing, service, or maintenance as described above, but also can be included as part of the normal operation of an exposure apparatus when it is desired to finely adjust the projection magnification by a predetermined amount. For example, when a pattern of the n-th layer is formed and the entire wafer is uniformly stretched when exposing the pattern of the (n+1)-th layer, according to the present invention, the projection magnification can be easily measured. It is possible to easily check after making a slight change in the spacing in FIG. According to such an exposure apparatus, the projection magnification can be changed in accordance with the expansion and contraction of the entire wafer. That is, if the wafer is stretched by a factor of 1, the projection magnification can be increased from the original value N times to kN times. To do this, we need a device that can change the projection magnification and accurately set it by moving the projection lens 6 and reticle 5 relative to each other in the optical axis direction according to commands from the CPtJ30 so that the measured magnification becomes the desired amount. , is not only effective when dealing with wafer expansion and contraction as described below, but also has another exposure device, for example, a soft X-ray radiation source, and performs proximity exposure at a finite distance from the radiation source. It is also effective to use both an X-ray exposure apparatus and a projection exposure apparatus in the manufacture of one device.

In other words, a circuit pattern of a certain layer is printed on a wafer using an exposure device such as an XSM optical device in which the magnification between the pattern dimension on the mask and the pattern dimension printed on the wafer differs by a minute amount with respect to an integer value. When printing circuit patterns on other layers using an optical projection exposure device, the magnification relationship between the two when manufacturing the mask or reticle used should be set to a perfect integer multiple or a fraction of an integer.
Even if it is doubled, it can be easily handled by adjusting the magnification on the projection exposure apparatus side, which has the advantage of making it easier to manufacture masks or reticles.

Similarly, the present invention can be applied not only to projection exposure devices, but also to extremely simple, accurate, and high-speed measurements when examining other projection lenses and imaging optical systems such as camera lenses. , its measurement can also be automated.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a projection exposure apparatus to which a measurement apparatus according to an embodiment of the present invention is applied, and FIG.
3 is a plan view showing a reticle, FIG. 3 is a plan view of a light shielding member provided on the stage of the exposure apparatus to form a small opening, FIG. 4 is a block diagram showing the control system of the exposure apparatus, and FIG. 5 is a plan view showing the reticle.
The figure shows the relationship between the size of the projected image when the mark is projected on the reticle and the size of the minute aperture. Figure 6 shows the light intensity distribution when the projected image of the mark is photoelectrically detected. Figure 7.8 is a diagram illustrating focus detection using a minute aperture and a photoelectric detector. [Explanation of symbols of main parts] 5... Reticle, 6... Projection lens 7
...Stage, 8...Minute aperture 9...
...Photoelectric detector, 30...CPU13.3
4...For laser interferometer Applicant: Nippon Kogaku Kogyo Co., Ltd. Agent Takao Watanabe

Claims (1)

[Claims] illumination means for illuminating a mask on which predetermined marks are drawn at a plurality of predetermined positions; photoelectrically detecting a mark projection image of the mask projected by an imaging optical system to be measured; a photoelectric detection means that is two-dimensionally movable within a projection plane; and a coordinate measurement means that measures the coordinates of the projection position of the mark projection image according to the output of the photoelectric detection means, and a plurality of measured marks. A characteristic measuring device for an imaging optical system, characterized in that the optical characteristics of the imaging optical system can be calculated based on each projection position information of a projected image and each position information of a mark on a mask.