JP2011086876A - Charged-particle beam resolution measuring method and charged-particle beam lithography apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged-particle beam resolution measuring method and a charged-particle beam lithography apparatus, which finds the beam resolution of the lithography apparatus itself. <P>SOLUTION: This electron beam lithography apparatus has: a radiation section 10 that radiates electron beam 54; a detector 32 that detects reflective signals obtained by scanning the electron beam 54 on marks 101 and 102; and a resolution acquisition section 35 that obtains the resolution of the electron beam 54 by fitting waveforms based on the reflective signals, by using an approximate expression defined by two shape functions that correspond to the marks 101 and 102 and an error function. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charged particle beam resolution measuring method and a charged particle beam drawing apparatus.

  In recent years, the circuit line width required for a semiconductor element has become increasingly narrower as the large scale integrated circuit (LSI) is highly integrated and has a large capacity. The semiconductor element uses an original pattern pattern (a mask or a reticle, which will be collectively referred to as a mask hereinafter) on which a circuit pattern is formed, and the circuit is exposed and transferred onto a wafer by a reduction projection exposure apparatus called a stepper. Manufactured by forming. For manufacturing a mask for transferring such a fine circuit pattern onto a wafer, an electron beam drawing apparatus capable of drawing the fine pattern is used. Attempts have also been made to develop a laser beam drawing apparatus for drawing using a laser beam. The electron beam drawing apparatus is also used when drawing a pattern circuit directly on a wafer.

  By the way, an improvement in yield is indispensable for manufacturing an LSI with a large cost. On the other hand, as represented by a 1 gigabit class DRAM (Random Access Memory), the pattern constituting the LSI is going to be on the order of submicron to nanometer. Here, the accuracy and minimum resolution of the pattern formed using the electron beam lithography apparatus are closely related to the resolution of the electron beam, and the resist resolution, for example, the patterning property of the chemically amplified resist, etc. Also related to process factors. In recent electron beam drawing apparatuses, the beam resolution of the drawing apparatus itself has been improved, and has reached a value that is equal to or smaller than the resolution determined by the process factors.

  The resolution of the electron beam can be obtained from the intensity distribution of the electron beam. Patent Document 1 describes a method for obtaining an electron beam intensity distribution. According to this method, the intensity distribution of the electron beam is obtained by irradiating an electron beam onto a metal mark having an area sufficiently smaller than the beam size and measuring the reflected electrons from the metal mark.

Japanese Patent Laid-Open No. 4-242919

  However, the resolution of the electron beam obtained as described above is larger than the beam resolution of the drawing apparatus itself. The cause of this is, for example, scattered electrons from the metal mark when the metal mark is irradiated with the electron beam. Therefore, in order to obtain the beam resolution of the drawing apparatus itself, it is necessary to eliminate the influence of such a cause.

  The present invention has been made in view of these points. That is, an object of the present invention is to provide a charged particle beam resolution measuring method capable of measuring the beam resolution of the drawing apparatus itself.

  Another object of the present invention is to provide a charged particle beam drawing apparatus capable of obtaining the beam resolution of the drawing apparatus itself.

  Other objects and advantages of the present invention will become apparent from the following description.

A first aspect of the present invention includes a step of scanning a charged particle beam over a plurality of marks on a substrate and detecting a reflected signal from the plurality of marks;
Charging using a number of shape functions corresponding to a plurality of marks and an approximate expression defined by one error function and fitting a waveform based on a reflection signal to obtain a resolution of the charged particle beam. The present invention relates to a particle beam resolution measurement method.

A second aspect of the present invention includes a first step of scanning a charged particle beam over a plurality of marks on a substrate and detecting a reflected signal from the plurality of marks;
A second equation for obtaining a resolution σ ₁ of a charged particle beam by fitting a waveform based on a reflection signal in the first step using an approximate expression defined by a number of shape functions corresponding to a plurality of marks and one error function Process,
A third step of scanning the charged particle beam again on the plurality of marks and detecting reflected signals from the plurality of marks after a predetermined time has elapsed after finishing the second step;
A fourth equation for obtaining a resolution σ ₂ of a charged particle beam by fitting a waveform based on a reflection signal in the third step using an approximate expression defined by a number of shape functions corresponding to a plurality of marks and one error function Process,
The present invention relates to a charged particle beam resolution measuring method characterized by comprising a resolution σ ₁ and a resolution σ ₂ and a fifth step of comparing each shape function in the second step and the fourth step.

The third aspect of the present invention includes a step of scanning a charged particle beam while changing the state of a charged particle beam on one mark on a substrate, and detecting a reflected signal from the mark;
Using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam, and fitting the waveform based on the reflected signal to obtain the resolution of the charged particle beam; The present invention relates to a charged particle beam resolution measuring method.

A fourth aspect of the present invention includes a first step of scanning a single particle on a substrate while changing the state of the charged particle beam and detecting a reflected signal from the mark;
A waveform based on the reflection signal in the first step is fitted using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam in the first step. A second step of determining the resolution σ ₁ of the charged particle beam,
After a predetermined time has passed after finishing the second step, a third step of scanning the mark again by changing the state of the charged particle beam and detecting a reflected signal from the mark;
A waveform based on the reflection signal in the third step is fitted using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam in the third step. A fourth step of determining the resolution σ ₂ of the charged particle beam;
The present invention relates to a charged particle beam resolution measuring method characterized by comprising a resolution σ ₁ and a resolution σ ₂ and a fifth step of comparing each shape function in the second step and the fourth step.

According to a fifth aspect of the present invention, an irradiation unit that irradiates a charged particle beam;
A detection unit for detecting reflected signals from a plurality of marks obtained by scanning a charged particle beam on the plurality of marks;
A resolution acquisition unit for acquiring a resolution of a charged particle beam by fitting a waveform based on a reflection signal using an approximate expression defined by a number of shape functions corresponding to a plurality of marks and one error function; The present invention relates to a charged particle beam drawing apparatus.

A sixth aspect of the present invention includes an irradiation unit that irradiates a charged particle beam;
A detection unit for detecting a reflected signal from the mark obtained by scanning the charged particle beam while changing the state of the charged particle beam on one mark;
Resolution that obtains the resolution of a charged particle beam by fitting a waveform based on a reflection signal using an approximate expression defined by one shape function corresponding to a mark and a number of error functions corresponding to the state of the charged particle beam The present invention relates to a charged particle beam drawing apparatus including an acquisition unit.

  According to the first aspect of the present invention, since the charged particle beam is scanned on the plurality of marks on the substrate and the reflected signals from the plurality of marks are detected, the state of the electron beam is not changed without changing the state of the electron beam. It can be measured while changing the shape. Therefore, since the mark shape function can be obtained more accurately than in the conventional method, the resolution of the obtained electron beam becomes more accurate.

According to the second aspect of the present invention, the charged particle beam is scanned on the plurality of marks on the substrate, the resolution σ ₁ of the charged particle beam is obtained by detecting the reflected signal from the plurality of marks, and the predetermined time Then, the same process is performed again to obtain the resolution σ ₂ of the charged particle beam. By comparing the resolution σ ₁ and the resolution σ ₂ with the shape functions in the second step and the fourth step, respectively, it is possible to know a decrease in resolution and a change in the mark. In other words, it is possible to distinguish between a decrease in resolution and a deterioration in marks.

  According to the third aspect of the present invention, scanning is performed while changing the state of the charged particle beam on one mark on the substrate, and the reflected signal from the mark is detected, so the measurement is performed with the same mark shape. can do. Therefore, since the intensity distribution error function of the electron beam can be obtained more accurately than in the conventional method, the resolution of the obtained electron beam becomes more accurate.

According to the fourth aspect of the present invention, the charged particle beam is scanned on a single mark on the substrate while the state of the charged particle beam is changed, and the resolution σ ₁ of the charged particle beam is obtained by detecting the reflected signal from the mark. After a predetermined time has elapsed, the same process is performed again to determine the resolution σ ₂ of the charged particle beam. By comparing the resolution σ ₁ and the resolution σ ₂ with the shape functions in the second step and the fourth step, respectively, it is possible to know a decrease in resolution and a change in the mark. In other words, it is possible to distinguish between a decrease in resolution and a deterioration in marks.

  According to the fifth aspect of the present invention, the detection unit detects the reflected signal obtained by scanning the charged particle beam on the plurality of marks, and the resolution acquisition unit detects the number of shape functions corresponding to the plurality of marks. The approximate expression defined by one error function is used to fit the waveform based on the reflected signal to obtain the resolution of the charged particle beam. Thereby, an accurate resolution can be obtained.

  According to the sixth aspect of the present invention, the detection unit detects the reflected signal obtained by scanning the charged particle beam while changing the state of the charged particle beam on one mark, and the resolution acquisition unit detects one shape corresponding to the mark. The approximate expression defined by the function and the number of error functions corresponding to the state of the charged particle beam is used to fit the waveform based on the reflected signal to obtain the resolution of the charged particle beam. Thereby, an accurate resolution can be obtained.

It is a block diagram of the electron beam drawing apparatus by this Embodiment. It is explanatory drawing of the beam resolution measuring method by 1 aspect of this Embodiment. It is a waveform of the electron beam intensity obtained by one mode of this embodiment. It is an example of the intensity distribution error function F (x) of an electron beam. It is an example of the shape function of a mark. It is explanatory drawing of the drawing method by an electron beam. It is an example of the usage method of the electron beam drawing apparatus of this Embodiment. It is another example of the usage method of the electron beam drawing apparatus of this Embodiment. It is another example of the usage method of the electron beam drawing apparatus of this Embodiment.

  FIG. 1 shows an electron beam drawing apparatus which is an example of a charged particle beam drawing apparatus of the present invention.

  In FIG. 1, a stage 3 on which a substrate S is placed is provided in a sample chamber 1. The substrate S is, for example, a silicon (Si) substrate, and a mark to be described later is provided on the surface thereof. The stage 3 is driven by the stage drive circuit 4 in the X direction (left and right direction on the paper surface) and the Y direction (vertical direction on the paper surface). The moving position of the stage 3 is measured by a position circuit 5 using a laser length meter or the like.

  As shown in FIG. 1, the substrate S is fixed on the stage 3 at a position that does not interfere with the sample 2 to be drawn. However, the substrate S can be carried into the sample chamber 1 from the outside of the drawing apparatus and placed on the stage 3 when measuring the resolution of the electron beam.

  An irradiation unit 10 that irradiates an electron beam is installed above the sample chamber 1. The irradiation unit 10 includes an electron gun 6, various lenses 7, 8, 9, 11, 12, a blanking deflector 13, a shaping deflector 14, a main deflector 15 for beam scanning, and a sub deflector 16 for beam scanning. , And two beam shaping apertures 17, 18 and the like.

  In one embodiment of the present embodiment, as shown in FIG. 2, marks 101 and 102 for measuring the resolution of the electron beam are provided on the substrate S. The marks 101 and 102 are formed of a material having a higher reflectance than the substrate S. For example, when the substrate S is a silicon (Si) substrate, the material constituting the mark 101 is preferably tantalum (Ta), tungsten (W), gold (Au), platinum (Pt), or the like. For example, a tantalum film provided on a silicon substrate and the tantalum film etched into a rectangular shape can be used as the marks 101 and 102. By applying a semiconductor manufacturing process to the manufacturing method of the marks 101 and 102, the pattern shape of the marks 101 and 102 can be made more accurate than the method by machining.

  In the example of FIG. 2, the electron beam 54 is scanned on the substrate S in the direction of the arrow. At this time, the electron beam 54 passes over the marks 101 and 102 in one scan. For example, the electron beam 54 scans from a direction orthogonal to one side of the rectangular mark 101 and then advances straight toward the mark 102 as it is. For example, as shown in FIG. 2, an electron beam 54 formed into a quadrangular shape is scanned toward the mark 101. When the mark 101 is irradiated with the electron beam 54, reflected electrons jump out of the mark 101. The reflected electrons that have jumped out are detected by a detector 32 provided above the sample chamber 1. When the electron beam 54 is further scanned and the mark 102 is irradiated with the electron beam 54, reflected electrons jump out of the mark 102. The reflected electrons that have jumped out are similarly detected by the detector 32.

  In the conventional method, only one mark is provided on the substrate, and the electron beam intensity distribution is obtained by scanning the electron beam and detecting the reflected electrons from the mark. However, the amount of reflected electrons detected varies depending on the shape of the mark and also varies depending on the resolution of the electron beam. In the above conventional method, although the influence of the process factor can be eliminated, when the resolution of the electron beam obtained by the measurement performed after a predetermined time from the previous measurement has changed, this is purely the resolution of the electron beam. It could not be distinguished whether it was due to fluctuations or the result of fluctuations in the shape of the mark.

  Therefore, in one aspect of this embodiment, a plurality of marks are provided on the substrate so that the electron beam passes over these marks in one scan. Then, using an approximate expression defined by the shape function of each mark and the intensity distribution error function of the electron beam, a waveform based on the reflected electron signal detected by the detector is fitted. Thereby, the resolution of the electron beam can be obtained. The number of marks is not limited, but two marks are sufficient for obtaining the resolution.

  Thus, in one aspect of this embodiment, an electron beam is passed over a plurality of marks in one scan, and the intensity distribution of the electron beam is obtained based on the reflected electrons from each detected mark. The stability of the electron beam can be observed in the electron beam drawing apparatus by a known method, and it may be considered that the state of the electron beam does not change during one scanning. That is, according to this method, measurement can be performed while changing the shape of the mark without changing the state of the electron beam. Therefore, since the mark shape function can be obtained more accurately than in the conventional method, the resolution of the obtained electron beam becomes more accurate.

  In FIG. 1, the detector 32 detects the reflected electrons generated when the marks 101 and 102 are irradiated with the electron beam 54 as a current value. The detector 32 may detect secondary electrons as current values in addition to the reflected electrons. The electrical signal output from the detector 32 is input to the detection unit 33. Then, after being amplified by the detection unit 33, it is input to the A / D conversion unit 34. The A / D converter 34 converts the analog signal from the detector 33 into a digital signal. The converted digital signal is sent to the control computer 19. Here, since the A / D converter 34 can accumulate the data from the detector 33, it is not necessary to transfer the data to the control computer 19 for each measurement. Therefore, the lengthening of the sampling time due to the communication time can be reduced.

  The resolution acquisition unit 35 provided in the control computer 19 uses an approximate expression defined by two shape functions corresponding to the marks 101 and 102 and one error function, and fits a waveform based on reflected signals from these marks. To obtain the resolution of the electron beam.

  The resolution acquisition unit 35 performs a differentiation operation on the signal sent from the A / D conversion unit 34 and obtains an absolute value thereof to obtain a waveform of the electron beam intensity. FIG. 3 is a waveform of the obtained electron beam intensity. In FIG. 3, the horizontal axis is the position in the electron beam scanning direction. When the electron beam 54 is scanned, first, reflected electrons that have jumped out when the mark 101 is irradiated with the electron beam 54 are observed. Then, when the electron beam 54 finishes passing through the mark 101, the reflected electrons are substantially not observed. Next, when the electron beam 54 is irradiated to the mark 102, the reflected electrons are emitted again and observed. When the observed reflected electron signal is differentiated, the electron beam intensity waveform shown in FIG. 3 is obtained. If there is a difference between the reflected electron signal from the mark 101 and the reflected electron signal from the mark 102, it can be said that the cause is the shape of the mark.

The resolution acquisition unit 35 uses the approximate expression defined by the mark shape function and the electron beam intensity distribution error function to determine the electron beam resolution from the waveform based on the obtained reflected electron signal. The approximate expression is defined by a convolution function of a mark shape function and an intensity distribution error function, as shown in Expression (1). As a result, an approximate function R (x) that substantially matches the waveform obtained by the measurement is obtained. P (x) is a mark shape function, and F (x) is an intensity distribution error function.

FIG. 4 is an example of the intensity distribution error function F (x) of the electron beam. Assuming that the resolution of the electron beam is σ and the width of the electron beam is 2 W, the intensity distribution error function F (x) is expressed by equation (2). According to the method of measuring reflected electrons so that an electron beam passes through a plurality of marks provided on the substrate in one scan, the same intensity distribution miscalculation function F ( x) can be applied.

  FIG. 5 is an example of a mark shape function. In general, the mark 101 and the mark 102 in FIG. 2 do not have the same function, and an appropriate shape function is obtained for each.

The mark shape function P (x) shown in FIG. 5 is expressed by equation (3). Function between two points of each position _x 1 ~x ₆ are respectively defined by the parameters _{a 1 ~a 6, b 1 ~b} 6.

  The electron beam intensity distribution error function F (x) of the electron beam and the parameters of the shape function P (x) of the mark are combined, and the electron beam obtained from the reflected electron signals observed at the marks 101 and 102 respectively. The intensity waveform is fitted with the approximation function R (x) of the equation (1) to obtain the beam resolution σ. According to this method, it is possible to obtain the original beam resolution σ of the electron beam in the electron beam writing apparatus alone, in which the dependency on the shape of the mark is eliminated.

  Next, another aspect of the present embodiment will be described.

  In another aspect of the present embodiment, scanning is performed by changing the state of the electron beam on one mark provided on the substrate. For example, scanning is performed by adjusting the focus of the optical system of the electron beam drawing apparatus and changing the blur amount of the beam. According to this method, the measurement can be performed in the same shape of the mark. Therefore, since the intensity distribution error function of the electron beam can be obtained more accurately than in the conventional method, the resolution of the obtained electron beam becomes more accurate.

  Also in this embodiment, as in the above-described embodiment, the parameters of the electron beam intensity distribution error function F (x) and the mark shape function P (x) are combined and obtained from the observed reflected electron signal. The waveform of the obtained electron beam intensity is fitted with the approximate function R (x) of the equation (1). The electron beam intensity distribution error function F (x) is obtained for each electron beam in different states, but the mark shape function P (x) is common to these electron beams. That is, the resolution acquisition unit of the control computer uses an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the electron beam, and generates a waveform based on the reflected signal from the mark. The resolution of the electron beam is obtained by fitting.

Furthermore, in another aspect of the present embodiment, a step of scanning one mark provided on the substrate while changing the state of the electron beam, and obtaining a waveform of the electron beam intensity from the detected reflected electrons. performed at time t _1, it is performed again at time t ₂ after a predetermined time followed. If a difference occurs in the resolution of the electron beam obtained at time t ₁ and time t ₂ , it is expected that some change has occurred in the mark. Here, as an example of the change, there is a deterioration of the mark due to the electron beam irradiation. Therefore, according to this embodiment, it is possible to know the mark replacement time.

  FIG. 6 is an explanatory diagram of a drawing method using an electron beam. As shown in this figure, the pattern 51 drawn on the sample 2 is divided into strip-shaped frame regions 52. The sample 2 is a mask in which a light shielding film such as a chromium film and a resist film are laminated on a glass substrate, for example. Drawing with the electron beam 54 is performed for each frame region 52 while the stage 3 continuously moves in one direction (for example, the X direction) in FIG. The frame area 52 is further divided into sub-deflection areas 53, and the electron beam 54 draws only necessary portions in the sub-deflection areas 53. The frame area 52 is a strip-shaped drawing area determined by the deflection width of the main deflector 15, and the sub-deflection area 53 is a unit drawing area determined by the deflection width of the sub-deflector 16.

  Positioning of the reference position of the sub deflection area is performed by the main deflector 15, and drawing in the sub deflection area 53 is controlled by the sub deflector 16. That is, the main deflector 15 positions the electron beam 54 in a predetermined sub-deflection region 53, and the sub-deflector 16 determines the drawing position in the sub-deflection region 53. Further, the shape and size of the electron beam 54 are determined by the shaping deflector 14 and the beam shaping apertures 17 and 18. Then, the sub-deflection area 53 is drawn while continuously moving the stage 3 in one direction. When drawing of one sub-deflection area 53 is completed, the next sub-deflection area 53 is drawn. When drawing of all the sub-deflection areas 53 in the frame area 52 is completed, the stage 3 is stepped in a direction orthogonal to the direction in which the stage 3 is continuously moved (for example, the Y direction). Thereafter, the same processing is repeated, and the frame area 52 is sequentially drawn.

  In FIG. 1, reference numeral 20 denotes an input unit, which is a part where drawing data to be drawn on the sample 2 is input to the electron beam drawing apparatus through a magnetic disk as a storage medium. The drawing data read from the input unit 20 is temporarily stored in the pattern memory 21 for each frame area 52. The pattern data for each frame region 52 stored in the pattern memory 21, that is, the frame information composed of the drawing position, drawing graphic data, etc., is corrected by drift correction etc. by the drawing data correction unit 31 and then subjected to data analysis. Are sent to the pattern data decoder 22 and the drawing data decoder 23, which are parts. Further, the drawing data correction unit 31 further performs position correction on the stage 3 with respect to the design value data subjected to drift correction. That is, the position data of the stage 3 measured by the position circuit 5 is sent to the drawing data correction unit 31 and added to the data of the design value subjected to drift correction. The synthesized data is sent to the pattern data decoder 22 and the drawing data decoder 23.

  Information from the pattern data decoder 22 is sent to a blanking circuit 24 and a beam shaper driver 25. Specifically, blanking data based on the data is created by the pattern data decoder 22 and sent to the blanking circuit 24. Desired beam size data is also created and sent to the beam shaper driver 25. Then, a predetermined deflection signal is applied from the beam shaper driver 25 to the shaping deflector 14 of the irradiation unit 10 to control the size of the electron beam 54.

  The deflection control unit 30 in FIG. 1 is connected to a settling time determination unit 29, the settling time determination unit 29 is connected to a sub deflection region deflection amount calculation unit 28, and the sub deflection region deflection amount calculation unit 28 is a pattern data decoder. 22 is connected. The deflection control unit 30 is connected to a blanking circuit 24, a beam shaper driver 25, a main deflector driver 26, and a sub deflector driver 27.

  The output of the drawing data decoder 23 is sent to the main deflector driver 26 and the sub deflector driver 27. Then, a predetermined deflection signal is applied from the main deflector driver 26 to the main deflector 15 of the irradiation unit 10, and the electron beam 54 is deflected and scanned to a predetermined main deflection position. Further, a predetermined sub deflection signal is applied from the sub deflector driver 27 to the sub deflector 16, and drawing in the sub deflection region 53 is performed.

  Next, a drawing method by the electron beam drawing apparatus will be described.

  First, the sample 2 is placed on the stage 3 in the sample chamber 1. Next, the position of the stage 3 is detected by the position circuit 5, and the stage 3 is moved to a position where drawing can be performed by the stage drive circuit 4 based on a signal from the control computer 19.

  Next, an electron beam 54 is emitted from the electron gun 6. The emitted electron beam 54 is collected by the illumination lens 7. Then, the blanking deflector 13 performs an operation for irradiating the sample 2 with the electron beam 54.

  The electron beam 54 incident on the first aperture 17 passes through the opening of the first aperture 17 and is then deflected by the shaping deflector 14 controlled by the beam shaper driver 25. And it passes through the opening part provided in the 2nd aperture 18, and becomes a beam shape which has a desired shape and a dimension. This beam shape is a drawing unit of the electron beam 54 applied to the sample 2.

  The electron beam 54 is shaped into a beam shape and then reduced by the reduction lens 11. The irradiation position of the electron beam 54 on the sample 2 is controlled by the main deflector 15 controlled by the main deflector driver 26 and the sub deflector 16 controlled by the sub deflector driver 27. The main deflector 15 positions the electron beam 54 in the sub deflection region 53 on the sample 2. The sub deflector 16 positions the drawing position in the sub deflection region 53.

  Drawing with the electron beam 54 on the sample 2 is performed by scanning the electron beam 54 while moving the stage 3 in one direction. Specifically, the pattern is drawn in each sub deflection region 53 while moving the stage 3 in one direction. After all the sub-deflection areas 53 in one frame area 52 have been drawn, the stage 3 is moved to a new frame area 52 and drawn similarly.

  After drawing all the frame regions 52 of the sample 2 as described above, the mask is replaced with a new mask, and drawing by the same method as above is repeated.

  Next, drawing control by the control computer 19 will be described.

  The control computer 19 reads the drawing data of the mask recorded on the magnetic disk by the input unit 20. The read drawing data is temporarily stored in the pattern memory 21 for each frame area 52.

  The drawing data for each frame area 52 stored in the pattern memory 21, that is, the frame information composed of the drawing position, the drawing graphic data, etc. is corrected by the drawing data correction unit 31, and then the pattern data as the data analysis unit. The data is sent to the sub deflection region deflection amount calculation unit 28, the blanking circuit 24, the beam shaper driver 25, the main deflector driver 26, and the sub deflector driver 27 via the decoder 22 and the drawing data decoder 23.

  The pattern data decoder 22 generates blanking data based on the drawing data and sends it to the blanking circuit 24. Further, desired beam shape data is created based on the drawing data, and is sent to the sub deflection region deflection amount calculation unit 28 and the beam shaper driver 25.

  The sub deflection region deflection amount calculation unit 28 calculates the deflection amount (movement distance) of the electron beam for each shot in the sub deflection region 53 from the beam shape data created by the pattern data decoder 22. The calculated information is sent to the settling time determination unit 29, and the settling time corresponding to the movement distance by the sub deflection is determined.

  The settling time determined by the settling time determination unit 29 is sent to the deflection control unit 30, and then the deflection control unit 30 measures the blanking circuit 24, the beam shaper driver 25, the main pattern while timing the pattern drawing. It is appropriately sent to either the deflector driver 26 or the sub deflector driver 27.

  In the beam shaper driver 25, a predetermined deflection signal is applied to the shaping deflector 14 of the irradiation unit 10 to control the shape and size of the electron beam 54.

  The drawing data decoder 23 generates positioning data for the sub deflection region 53 based on the drawing data, and this data is sent to the main deflector driver 26. Next, a predetermined deflection signal is applied from the main deflector driver 26 to the main deflector 15, and the electron beam 54 is deflected and scanned to a predetermined position in the sub deflection region 53.

  The drawing data decoder 23 generates a control signal for scanning the sub deflector 16 based on the drawing data. After the control signal is sent to the sub deflector driver 27, a predetermined sub deflection signal is applied from the sub deflector driver 27 to the sub deflector 16. Drawing in the sub deflection region 53 is performed by repeatedly irradiating the electron beam 54 after the settling time has elapsed.

FIG. 7 is an example of a method of using the electron beam drawing apparatus according to this embodiment. As shown in this figure, first, an electron beam is passed over a plurality of marks in one scan, and the intensity distribution of the electron beam is obtained based on the reflected electrons from each detected mark (S101). Next, the parameters of the electron beam intensity distribution error function F (x) and the mark shape function P (x) are combined, and the waveform of the electron beam intensity obtained from the reflected electron signal is approximated by the approximate function R ( A beam resolution σ is obtained by fitting at x) (S102). The obtained σ is compared with the reference value σ ₀ (S103). If σ ₀ ≧ σ, it is determined that there is no problem in resolution, and S101 to S103 are repeated at predetermined intervals. On the other hand, if σ> σ ₀ , it is determined that there is a problem in resolution, and the cause of the decrease in resolution is investigated (S104). As a cause of the reduction in resolution, for example, deterioration of an electron gun or a deflection lens can be considered.

FIG. 8 is another example of a method of using the electron beam drawing apparatus according to this embodiment. As shown in this figure, first, an electron beam is passed over a plurality of marks in one scan (S201). Then, a reflected signal from each mark is detected (S202). Next, the parameters in the electron beam intensity distribution error function F (x) and the mark shape function P (x) are combined, and the waveform of the electron beam intensity obtained from the reflected signal in S202 is approximated by the function R ( A beam resolution σ ₁ is obtained by fitting at x) (S203). After a predetermined time elapses after S203, the electron beam is scanned again on the plurality of marks (S204). Then, reflection signals from a plurality of marks are detected (S205). Next, using the approximate expression defined by the number of shape functions corresponding to a plurality of marks and one error function, the waveform based on the reflected signal in S205 is fitted to obtain the resolution σ _{2 of the} electron beam (S206). Thereafter, the resolution σ ₁ and the resolution σ ₂ are respectively compared with the shape functions of S203 and S206 (S207). If σ ₁ = σ ₂ and the shape functions are substantially the same, there is no change in the resolution of the electron beam and the mark, so S204 to S206 are performed after waiting for a predetermined time again. On the other hand, if σ ₁ = σ ₂ and the shape functions are different, it is determined that some change has occurred in the mark and the mark is exchanged. Further, if σ ₁ ≠ σ ₂ and the shape functions are substantially the same, it is determined that there is a problem in the resolution of the electron beam, and the cause of the reduction in resolution is investigated. As a cause of the reduction in resolution, for example, deterioration of an electron gun or a deflection lens can be considered.

FIG. 9 is another example of a method of using the electron beam drawing apparatus according to this embodiment. First, an electron beam is scanned on one mark under a predetermined condition (S301). Then, a reflection signal from the mark is detected (S302). Next, using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the electron beam in S301, the waveform based on the reflected signal in S302 is fitted to the electron beam. The resolution σ ₁ is obtained (S303). After a predetermined time elapses after S303, scanning is performed again by changing the state of the electron beam on the mark (S304). Then, a reflected signal from the mark is detected (S305). Next, using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the electron beam in S304, the waveform based on the reflected signal in S305 is fitted to fit the electron beam. The resolution σ ₂ is obtained (S306). Thereafter, the resolution σ ₁ and the resolution σ ₂ are respectively compared with the shape functions in S303 and S306 (S307). If σ ₁ = σ ₂ and the shape functions are substantially the same, there is no change in the resolution of the electron beam and the mark, so S304 to S306 are performed after waiting for a predetermined time again. On the other hand, if σ ₁ = σ ₂ and the shape functions are different, it is determined that some change has occurred in the mark and the mark is exchanged. Further, if σ ₁ ≠ σ ₂ and the shape functions are substantially the same, it is determined that there is a problem in the resolution of the electron beam, and the cause of the reduction in resolution is investigated. As a cause of the reduction in resolution, for example, deterioration of an electron gun or a deflection lens can be considered.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, although the electron beam is used in the above embodiment, the present invention can also be applied to cases where other charged particle beams such as an ion beam are used.

  In the above embodiments, descriptions of parts that are not directly required for the description of the present invention, such as the device configuration and control method, are omitted. However, the required device configuration and control method may be appropriately selected and used. Needless to say, you can.

DESCRIPTION OF SYMBOLS 1 Sample chamber 2 Sample 3 Stage 4 Stage drive circuit 5 Position circuit 6 Electron gun 7, 8, 9, 11, 12 Various lenses 10 Irradiation part 13 Blanking deflector 14 Molding deflector 15 Main deflector 16 Sub deflector 17 First aperture 18 Second aperture 19 Control computer 20 Input unit 21 Pattern memory 22 Pattern data decoder 23 Drawing data decoder 24 Blanking circuit 25 Beam shaper driver 26 Main deflector driver 27 Sub deflector driver 28 Sub deflection area deflection Quantity calculation unit 29 Settling time determination unit 30 Deflection control unit 31 Drawing data correction unit 32 Detector 33 Detection unit 34 A / D conversion unit 35 Resolution acquisition unit 51 Pattern to be drawn 52 Frame region 53 Sub deflection region 54 Electron beam 101, 102 Mark S Substrate

Claims (6)

Scanning a charged particle beam over a plurality of marks on a substrate to detect reflected signals from the plurality of marks;
Using an approximate expression defined by a number of shape functions corresponding to the plurality of marks and one error function, and fitting a waveform based on the reflected signal to obtain a resolution of the charged particle beam. A charged particle beam resolution measuring method. A first step of scanning a charged particle beam over a plurality of marks on a substrate and detecting reflected signals from the plurality of marks;
Using the approximate expression defined by the number of shape functions corresponding to the plurality of marks and one error function, the waveform based on the reflection signal in the first step is fitted to obtain the resolution σ ₁ of the charged particle beam. A second step;
A third step of scanning a charged particle beam again on the plurality of marks and detecting reflected signals from the plurality of marks after a predetermined time has elapsed after finishing the second step;
The approximate expression defined by the number of shape functions corresponding to the plurality of marks and one error function is used to fit the waveform based on the reflection signal in the third step to obtain the resolution σ ₂ of the charged particle beam. A fourth step;
A charged particle beam resolution measuring method comprising: a fifth step of comparing the resolution σ ₁ and the resolution σ ₂ with each shape function in the second step and the fourth step. Scanning a charged particle beam while changing the state of a charged particle beam on one mark on the substrate, and detecting a reflected signal from the mark;
By using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam, the waveform based on the reflected signal is fitted to the resolution of the charged particle beam. A method for measuring the resolution of charged particle beams. A first step of scanning a charged particle beam while changing the state of a charged particle beam on one mark on a substrate, and detecting a reflected signal from the mark;
Based on the reflection signal in the first step, using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam in the first step. A second step of fitting a waveform to obtain a resolution σ ₁ of the charged particle beam;
A third step of detecting a reflected signal from the mark by scanning the charged particle beam again on the mark after a predetermined time has elapsed after finishing the second step;
A waveform based on the reflection signal in the third step using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam in the third step. A fourth step of obtaining a resolution σ ₂ of the charged particle beam by fitting
A charged particle beam resolution measuring method comprising: a fifth step of comparing the resolution σ ₁ and the resolution σ ₂ with each shape function in the second step and the fourth step. An irradiation unit for irradiating a charged particle beam;
A detection unit for detecting reflected signals from the plurality of marks obtained by scanning the charged particle beam on the plurality of marks;
A resolution acquisition unit that acquires a resolution of the charged particle beam by fitting a waveform based on the reflected signal using an approximate expression defined by a number of shape functions corresponding to the plurality of marks and one error function; A charged particle beam drawing apparatus. An irradiation unit for irradiating a charged particle beam;
A detector that detects a reflected signal from the mark obtained by scanning the charged particle beam while changing the state of the charged particle beam on one mark;
By using an approximate expression defined by one shape function corresponding to the mark and a number of error functions corresponding to the state of the charged particle beam, the waveform based on the reflected signal is fitted to the resolution of the charged particle beam. A charged particle beam drawing apparatus comprising: a resolution acquisition unit that acquires

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