JP3838771B2 - Electron beam incident angle measuring method in electron beam exposure apparatus and exposure method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron beam incident angle measurement method in an electron beam exposure apparatus and an exposure method using the same, and more particularly to correction when a sample (wafer) has irregularities.
With the progress of microfabrication technology, semiconductor integrated circuits tend to be more highly integrated, and the performance required for microfabrication technology has become increasingly severe. In particular, in the exposure technique, the limit of the light exposure technique used for a conventionally used stepper or the like is expected. The electron beam exposure technique is a technique that is highly likely to assume the next generation of microfabrication instead of the light exposure technique, but a lack of processing speed compared to the light exposure technique has become a technical problem.
[0002]
[Prior art]
FIG. 1 is a diagram showing a configuration of a beam irradiation system in an electron beam exposure apparatus. In FIG. 1, reference numeral 11 is an electron gun that generates an electron beam, 12 is a first converging lens that converts the electron beam from the electron gun 11 into a parallel beam, and 13 is a parallel beam that passes through it into a predetermined shape. 14 is a second converging lens that narrows the shaped beam, 15 is a shaping deflector, 16 is a first mask deflector, and 17 is a mask that dynamically corrects astigmatism. 18 is a second mask deflector, 19 is a converging coil for mask, 20 is a first molding lens, 21 is a mask for block exposure moved by the stage 21A, and 22 is The second shaping lens, 23 is a third mask deflector, 24 is a blanking deflector for controlling on / off of the beam, 25 is a fourth Max deflector, and 26 is a third deflector. Lens, 27 is a circular aperture , 28 is a reduction lens, 29 is a focus coil, 30 is a projection lens, 31 is an electromagnetic main deflector, and 32 is an electrostatic sub-deflector. A beam (10) is irradiated onto the sample (wafer). The wafer 1 is attracted and held by a stage (not shown), and the stage moves the wafer 1 two-dimensionally in a plane perpendicular to the electron beam 10.
[0003]
In order to expose a desired pattern, a mask to be exposed is selected by controlling the deflectors 15 to 18, 22 and 24 according to the pattern data, and an electron beam having the selected mask shape is irradiated to a desired position. Then, the main deflector 31 and the sub deflector 32 are controlled, and the blanking deflector 24 is controlled so as to be irradiated when it reaches a desired position. Since the deflection amounts of the main deflector 31 and the sub deflector 32 do not change linearly, the deflection amount corresponding to the pattern data is corrected by the pattern correction circuit 35 and then the main deflector via the DAC / AMP 33 and the DAC / AMP 34. 31 and the sub deflector 32, respectively. Since the electron beam exposure apparatus is widely known, further description of the electron beam exposure apparatus is omitted here.
[0004]
The wafer 1 is provided with an alignment mark (alignment mark) in advance for each chip in order to define an exposure position. When exposure is performed with an electron beam, the alignment mark is scanned by scanning the alignment mark with the electron beam. The position was detected, and the exposure position was determined based on the detected position. The wafer 1 is exposed after being electrostatically attracted to the stage, but the exposure surface is not flat but has an unevenness with respect to the ideal exposure surface due to curvature, and the height of the exposure surface depends on the position. Different. When the height of the exposure surface changes, the focus (focus) state of the electron beam changes, and it is necessary to change the focus by controlling the current flowing through the focus coil 29 accordingly.
[0005]
On the other hand, the optical axis of the electron beam of the electron beam exposure apparatus generally has an inclination of about several mrad with respect to the moving surface of the wafer stage. Therefore, a positional shift caused by the axial shift of the focus coil 29 occurs by changing the focus position. Since the misalignment caused by the axis deviation of the focus coil 29 can be measured, the misalignment caused by the axis deviation of the focus coil 29 can be easily corrected. Further, since the optical axis is tilted, the irradiation position is shifted when the height of the wafer is changed. FIG. 2 is a diagram for explaining the occurrence of deviation of the beam irradiation position when the height of the exposure surface of the wafer 1 is different. The electron beam is an electron beam when the deflection amount is zero, that is, the optical axis of the apparatus is inclined with respect to the moving surface of the wafer stage, and the incident angle of the electron beam when deflected is the inclination of the optical axis. The amount is obtained by adding the deflection of the angle of the electron beam due to the deflection. As shown in the figure, the error due to the tilt of the optical axis affects the exposure range in the same manner, and the deflection of the angle of the electron beam due to the deflection appears as a change in the exposure field size.
[0006]
Conventionally, the deviation due to the height of the exposure surface as described above has been corrected as follows. That is, the height dependence of the deflection efficiency of the deflector is measured, the position deviation due to the axis deviation of the focus coil is measured, the height distribution of the wafer surface is measured at a plurality of points on the wafer surface, and this height distribution is calculated. Approximate the function and obtain the height of the position on the wafer surface from the approximated function, and correct the misalignment caused by the focus and focus coil and the deflection efficiency of the deflector based on the above measurement results. Then, the position of the alignment mark is detected. The pattern is exposed based on the alignment marks detected in this way. Accordingly, when the position of the alignment mark of the wafer having the height distribution is detected by such a method, a positional deviation distribution proportional to the height distribution is obtained by adding to the actual position accuracy of the wafer. .
[0007]
FIG. 3 is a diagram for explaining correction of deviation due to the height of the exposure surface according to the above-described conventional method. The deflection efficiency is changed according to the height of the exposure surface, and exposure is performed at substantially the same position regardless of the height. The
[0008]
[Problems to be solved by the invention]
However, the correction by changing the deflection efficiency is only due to the deflection of the beam due to the deflection, and the offset due to the tilt of the optical axis cannot be corrected. Until now, no method for measuring the tilt of the optical axis with high accuracy has been known, and offset correction based on the tilt of the optical axis has not been performed.
[0009]
Furthermore, the conventional method for correcting the deviation due to the height of the exposure surface is performed by detecting an alignment mark provided for each chip on the wafer. This is because it has been considered that it is difficult to secure the alignment accuracy of the alignment mark over the entire wafer to a sufficient level, and the height distribution of the wafer is added to the misalignment of the alignment mark as described above. For this reason, when the height of the chip is different, the alignment accuracy of the alignment mark changes for each chip. However, detecting the alignment mark for each chip increases the time required to detect the alignment mark as a whole wafer, and causes a problem of reducing processing efficiency.
[0010]
On the other hand, there is an alignment method called global alignment in which alignment marks are not detected for each chip, but only a few chips are detected on the entire wafer. This global alignment method is a method generally used in a photo stepper or the like. By detecting alignment marks of several chips among chips arranged on a wafer, coordinate information of the chip arrangement is obtained and based on this. Exposure method. The advantages of this method are: (1) A more accurate alignment is possible by averaging random errors of each point, and (2) Processing time is reduced because the number of measurement points is reduced. That is. The biggest problem with an electron beam exposure apparatus that directly draws on a current wafer is the length of processing time, and it is desirable to perform global alignment because of the advantage (2).
[0011]
However, the precondition for guaranteeing the exposure position accuracy with global alignment is that the chip alignment on the underlying wafer is high, that is, the chip alignment mark is high over the entire wafer, and that the exposure apparatus The stage accuracy is high. Under such preconditions, the chip arrangement coordinates detected by the exposure apparatus become highly accurate lattice points, and the entire coordinate system can be obtained with high accuracy by detecting very few chips.
[0012]
As described above, the wafer is electrostatically attracted to the stage, but due to recent advances in alignment mark formation technology, the alignment accuracy of the alignment mark when it is attracted and corrected to a flat surface is quite good and sufficiently global. Alignment has reached a level that can be applied. However, in the conventional method for correcting the deviation due to the height of the exposure surface, as described above, the height distribution affects the detection of the alignment mark, and the position of the detected alignment mark is shifted accordingly, so a small number of chips. When the alignment mark on the wafer is detected and the coordinate system on the wafer is calculated, the overlay accuracy is degraded due to the deviation. Therefore, the conventional method for correcting the deviation due to the height of the exposure surface has a problem that alignment is performed by detecting alignment marks for each chip, not global alignment, and processing time required for alignment is long.
[0013]
As described above, there has been no known method for easily measuring the incident angle of an electron beam with high accuracy. Further, in the conventional method, even if the inclination of the optical axis of the electron beam exposure apparatus, that is, the incident angle of the electron beam cannot be measured, if the position of the alignment mark is accurately detected, there is almost no problem in terms of exposure accuracy. . However, alignment marks are detected for each chip, and it is difficult to improve the throughput of the apparatus. In this way, such a problem can be said to have emerged as a result of pursuing the maximum precision and throughput.
[0014]
The present invention is to solve such a problem, and by enabling global alignment to be applied in an exposure method for correcting a deviation due to height with respect to samples (wafers) having different surface heights, It is an object to improve the throughput of an electron beam exposure apparatus.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, first, it is possible to easily measure the incident angle (the inclination of the optical axis) of the electron beam with respect to the sample (wafer) surface. Therefore, in the electron beam exposure angle measurement method in the electron beam exposure apparatus according to the first aspect of the present invention, the heights of the position detection marks having different heights are measured and the positions are determined. Detecting with an electron beam, the incident angle is measured from the relationship between the position shift and the height.
[0016]
That is, the electron beam incident angle measuring method in the electron beam exposure apparatus according to the first aspect of the present invention is an electron beam incident angle measurement that measures the incident angle of the electron beam to the sample when the sample is irradiated with the electron beam. A method of preparing a measurement sample having irregularities on the surface, position detection marks provided at different heights, and the precise arrangement position of the position detection marks being known, and measurement A sample to be introduced into an electron beam exposure apparatus, the step of measuring the height distribution of the surface of the sample for measurement, the step of detecting the position of the mark for position detection by the electron beam, and the known position detection Depends on the height of the electron beam based on the correlation between the detection position deviation, which is the difference between the precise positioning accuracy of the mark and the position of the detected position detection mark, and the height of the position detection mark obtained from the height distribution. Seeking sex And a step, the height dependence of the electron beam, i.e., and calculates the distribution of the incident angle to the sample.
[0017]
FIG. 4 is a diagram for explaining the detection principle of the electron beam incident angle measurement method in the electron beam exposure apparatus according to the first aspect of the present invention. As shown in (1) of FIG. 4, it is assumed that the mark 2a is on a wafer having a surface that coincides with the reference plane 41. If the surface of the wafer is curved as indicated by 42, the mark is at a height indicated by 2b. When this mark is detected by the tilted electron beam 10, it is detected on the reference plane 41 so as to be at the position 2c, and a positional deviation occurs between the mark 2a. This positional deviation is an amount obtained by multiplying the inclination of the electron beam 10 by the height. Conversely, if the height and the positional deviation are known, the inclination of the electron beam 10 at that portion can be detected. (2) of FIG. 4 is a diagram showing a state of displacement when a lattice point on a wafer curved concentrically with an electron beam having a constant inclination is detected.
[0018]
In any case, the distribution of the incident angle of the electron beam can be obtained by the method of the first aspect of the present invention. Conventionally, the incident angle of the electron beam has not been measured, but can be easily measured by the method of the present invention.
For measurement using the method according to the first aspect of the present invention, wherein the surface has irregularities, the position detection marks are provided at different heights, and the precise position of the position detection marks is known. As the sample, for example, a sample in which the position detection mark is sufficiently accurately arranged is used, or a sample in which the arrangement accuracy of the position detection mark is sufficiently accurately measured is used, and a thin film is deposited thereon. It is created by bending the position detection mark and varying the height of the position detection mark.
[0019]
Although there is a concern about misalignment caused by bending the wafer, this is a cosine error and can be very small. If the inclination angle of the wafer surface due to the curvature is 0.5 mrad or less, the deformation can be 0.25 ppm or less. Therefore, even if the wafer is about 152 mm (6 inches), it is possible to have a height difference of 20 μm or more as long as deformation does not become a problem. If there is local elastic deformation, the position accuracy will be affected. For example, if a thin film with uniform stress is deposited and gently deformed, it will be curved and uneven without affecting the position accuracy. be able to.
[0020]
In the method according to the first aspect of the present invention, no matter how much the positional deviation is known, there is a change in the rotation angle of the wafer when it is introduced into the electron beam exposure apparatus and an expansion due to a temperature change. May occur. However, since such a linear distortion is observed as a first-order inclination component of the stage coordinates of the apparatus, it is separated from the nonlinear distortion distribution when a mark on an uneven wafer is detected by a beam having an incident angle. be able to.
[0021]
Therefore, by using the method according to the first aspect of the present invention, a first-order inclination component is calculated from at least three height measurement values of the height distribution of the surface of the measurement sample, and the inclination component is used as the height distribution. The first-order inclination component is calculated from the step of calculating the correction height distribution by subtracting from the detection position deviation of at least three or more position detection marks, and the inclination component is subtracted from the deviation of the detection position to determine the correction detection position. A step of calculating a deviation, and in the step of calculating the distribution of incident angles, the distribution of incident angles is calculated from the correlation between the corrected height distribution and the corrected detection position.
[0022]
When the pattern is exposed on the sample, the incident angle of the electron beam is measured in advance by the method of the first aspect. Then, the height distribution of the sample is measured, the position of the alignment mark (alignment mark) of several chips is detected with an electron beam, and the position of the mark is corrected by subtracting the deviation due to the incident angle and height from the detected position. Then, a chip array lattice is obtained based on the corrected mark position, and exposure is performed while correcting the positional shift accordingly.
[0023]
That is, the exposure method in the electron beam exposure apparatus according to the second aspect of the present invention comprises an electron beam generator for generating an electron beam, an electron beam shaping means for shaping the electron beam, and the electron beam on the sample surface. An electron optical column including an electron beam converging means, an electron beam deflecting means for deflecting the electron beam, a sample moving means for moving the sample in a plane perpendicular to the electron beam, and controlling the electron optical column and the sample moving means An exposure method for exposing a pattern onto a wafer having a height distribution using an electron beam exposure apparatus comprising a control means for performing the distribution of the incident angle of the electron beam to the sample by the method of the first aspect , Measuring the height distribution of the sample, selecting several chips from the chips on the sample, and selecting the position of the alignment mark of the selected chip by the electron beam Calculating the incident angle and height at the alignment mark from the distribution process and the distribution of the incident angle and the height distribution, calculating the misalignment due to the incident angle and height, and deviating from the position of the detected alignment mark. Subtracting the height correction mark position from the height correction mark position and obtaining the chip array grid on the sample based on the height correction mark position, and exposing from the incident angle distribution and height distribution according to the chip array grid It is characterized in that a pattern is exposed on a wafer while correcting a positional shift in the position.
[0024]
In the exposure method in the electron beam exposure apparatus of the present invention, since the distribution of the incident angle of the electron beam is measured in advance, if the height distribution of the sample is measured, the positional deviation due to the height is calculated and this amount is removed. Is possible. As described above, with the recent technology, the alignment accuracy of the alignment mark is sufficiently good, the position of the mark from which the displacement has been removed is highly accurate, and the global alignment method can be applied sufficiently. At the time of exposure, the exposure is performed while correcting the positional deviation at the exposure position from the distribution of the measured incident angles and the height distribution.
[0025]
When a plurality of samples (wafers) are continuously exposed, ones with different alignment mark heights are selected, and one of them is used as a measurement sample. The position of the alignment mark on the sheet is accurately measured outside, and the distribution of incident angles is measured by the method of the first aspect. Hereinafter, this one sheet and the remaining sample are exposed by the exposure method of the second aspect.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
In the following, embodiments of the present invention will be described. In order to simplify the description, the following two points are assumed. (1) In the embodiment, it is assumed that the focus coil of the electron beam exposure apparatus has no axis shift, and even if the focus position is changed by the focus coil, there is no position shift associated therewith. In an actual electron beam exposure apparatus, there is an axial misalignment, but this can be corrected as described above. Therefore, it is possible to prevent an apparent misalignment, and such an assumption is made. There is no loss of generality. Further, (2) the measurement wafer used in the examples is assumed to have marks arranged with sufficient accuracy. If the accuracy of the measurement wafer is insufficient, the total position measurement device can measure the mark displacement sufficiently accurately, and this measurement data can be subtracted from the measurement data obtained by the electron beam exposure device. This assumption does not particularly lose the generality of the embodiment.
[0027]
FIG. 5 is a diagram showing the configuration of an electron beam exposure apparatus used in the embodiment of the present invention. Reference numeral 9 denotes an electron optical column of the electron beam exposure apparatus, which has a configuration as shown in FIG. As shown in FIG. 1, reference numeral 1 is a wafer, 10 is an electron beam, 29 is a focus coil, 31 is a main deflector (main differential), and 32 is a sub-deflector (sub-deflector). ). The wafer 1 is electrostatically attracted and held on the stage 36 and can move in a plane perpendicular to the electron beam irradiation direction. Reference numeral 37 is a laser displacement meter, which measures the height distribution of the surface of the wafer 1 held on the stage 36.
[0028]
FIG. 6 is a flowchart showing a process for measuring the distribution of the incident angle of the electron beam of the electron beam exposure apparatus in the embodiment. The incident angle distribution measurement process will now be described.
In step 101, a measurement wafer 1 in which marks are arranged with high accuracy on lattice points as shown in FIG. 7 is created. In step 102, the measurement wafer 1 is curved by depositing a thin film of 1 μm or less on the measurement wafer 1. For example, if the measurement wafer 1 is a wafer of about 152 mm (6 inches) due to the deposition of this thin film, a height difference of about 20 μm occurs. The thin film to be deposited is preferably a material having a large atomic weight and conductivity so that detection by an electron beam is easy. Moreover, in order to bend concentrically, it is necessary to deposit so that stress may become uniform. Actually, tungsten (W), which is a semiconductor wiring material, was deposited by sputtering or the like.
[0029]
In step 103, the measurement wafer 1 is attracted to the stage 36 and moved to the laser displacement meter 37 to measure the height distribution Hij of the wafer surface at the mark position. In this embodiment, the height of the wafer is measured by the laser displacement meter 37, but the mark portion is scanned while changing the focus of the electron beam, and the height from the focus when the sharpest image is detected is determined. It is also possible to measure.
[0030]
In step 104, the mark on the measurement wafer 1 is scanned with an electron beam to detect the position of the mark, and the difference between the known mark position and the detected mark position, that is, the amount of displacement (δxij, δyij) (i = 1,2,3, ..., N, j = 1,2,3, ..., M). At this time, the focus position is adjusted by the focus coil so that the electron beam forms a sufficiently sharp image at the corner mark, but it is assumed that there is no beam position shift due to this focus change as described above. FIG. 8 shows an example of the distribution of one δxij of the displacement amount measured in step 104.
[0031]
In step 105, the slope component represented by the linear expression of the position of the grid point is obtained and subtracted from each of the measured height distribution Hij and the positional deviation amounts δxij and δyij by the least square method or the like, H′ij, δx′ij, and δy′ij whose inclination components are corrected are obtained. An example of the distribution of δx′ij thus obtained is shown in FIG. As shown in FIG. 10, the height dependency of the electron beam position, that is, the incident angle of the electron beam, is obtained by obtaining the correlation between H′ij and δx′ij and δy′ij thus obtained. In FIG. 10, δx′ij and δy′ij are distributed on straight lines, and these straight lines represent components of the XZ plane and YZ plane of the inclination of the optical axis of the electron beam.
[0032]
As described above, the incident angle of the electron beam, that is, the inclination of the optical axis can be measured. The tilt of the optical axis of the electron beam exposure apparatus does not change greatly once it is manufactured, but it changes to some extent depending on environmental conditions and the like, so it is desirable to measure it every day or periodically every predetermined time.
FIG. 11 is a flowchart showing the exposure process in the present embodiment. With reference to FIG. 11, the exposure process in the Example of this invention is demonstrated.
[0033]
It is assumed that the tilt of the optical axis of the electron beam exposure apparatus has already been measured by the method of the above embodiment. The wafer to be used is provided with an alignment mark for each chip, and the alignment mark is arranged with sufficient accuracy. As described above, in recent technologies, it is possible to form alignment marks with a level of arrangement accuracy that enables global alignment, and this is a condition that enables global alignment in this embodiment.
[0034]
In step 111, the height distribution of the wafer is measured by the same method as in step 103 of FIG. In step 112, the position of a chip at an appropriate position among the chips on the wafer, for example, the four chips at the peripheral four corners, or the position of five alignment marks obtained by adding the center chip to this, is obtained to obtain the positional deviation distribution. . In step 113, using the height distribution measured in step 111 and the incident angle of the electron beam that has already been measured, it is converted into positional deviation distribution data at the standard height H0. For example, if positional deviation data of (δx, δy) is obtained at the height H, this is converted into δ′x and δ′y according to the following equation.
[0035]
δx ′ = δx− (H−H0) × αx
δy ′ = δy− (H−H0) × αy
(However, αx and αy are components of the incident angle of the electron beam in the X-axis and Y-axis directions.)
In step 114, the coordinate system of the array lattice of the wafer is obtained by the least square method from the positional deviation distribution data converted into the deviation at the standard height.
[0036]
In step 115, the pattern is exposed while correcting the positional deviation depending on the height in accordance with the coordinate system of the array grid.
[0037]
【The invention's effect】
As described above, according to the present invention, the inclination of the optical axis of the electron beam exposure apparatus, that is, the incident angle of the electron beam can be easily measured with high accuracy. Even for a wafer having a height distribution, the deviation at the time of position detection by the electron beam can be determined by the measured incident angle and height of the electron beam. Can be sought. Therefore, if the alignment marks are arranged with high accuracy at a level where global alignment is possible, the global alignment method can be applied and the throughput of the apparatus is improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an electron optical column portion of an electron beam exposure apparatus.
FIG. 2 is a diagram for explaining the occurrence of a shift in irradiation position due to a change in height of an exposure surface.
FIG. 3 is a diagram for explaining a method of correcting an influence due to height in a conventional example.
FIG. 4 is a diagram illustrating the principle of detection of an electron beam incident angle according to the present invention.
FIG. 5 is a view showing a configuration of an electron beam exposure apparatus used in an embodiment of the present invention.
FIG. 6 is a flowchart showing a measurement process of an incident angle of an electron beam in the embodiment.
FIG. 7 is a diagram illustrating an example of a measurement sample (wafer) in an example.
FIG. 8 is a diagram showing an example of measurement data in an example.
FIG. 9 is a diagram illustrating an example of data after wafer tilt correction in the embodiment.
FIG. 10 is a diagram showing how to determine the incident angle of an electron beam in an example.
FIG. 11 is a flowchart showing height correction processing during exposure in the embodiment.
[Explanation of symbols]
1 ... Sample (wafer)
DESCRIPTION OF SYMBOLS 9 ... Electro-optic column 10 ... Electron beam 11 ... Electron gun 29 ... Focus coil 31 ... Main deflector (main deflector)
32 ... Sub-deflector
37 ... Laser displacement meter

Claims (3)

In the electron beam exposure apparatus, an electron beam incident angle measurement method for measuring an incident angle of the electron beam to the sample when the sample is irradiated with the electron beam,
Providing a measurement sample having irregularities on the surface, the position detection marks are provided at different heights, and the precise arrangement position of the position detection marks is known;
Introducing the measurement sample into the electron beam exposure apparatus and measuring the height distribution of the surface of the measurement sample;
Detecting the position of the position detection mark by the electron beam;
The detection position shift, which is the difference between the precise positioning accuracy of the position detection mark and the detected position of the detected position detection mark, and the height of the position detection mark obtained from the height distribution A step of obtaining the height dependency of the electron beam from the correlation of
Calculate the distribution of the incident angle to the sample from the height dependence of the electron beam ,
The measurement sample is formed by depositing a thin film on the measurement sample in which the position detection mark is sufficiently accurately arranged or the arrangement accuracy of the position detection mark is measured with sufficient accuracy. An electron beam incident angle measurement method in an electron beam exposure apparatus , wherein the measurement sample is bent and the height of the position detection mark is made different . An electron beam incident angle measuring method in the electron beam exposure apparatus according to claim 1 ,
Calculate a first-order inclination component from at least three height measurement values of the measured surface height distribution of the measurement sample, and subtract the inclination component from the height distribution to calculate a corrected height distribution. And a process of
Calculating a primary inclination component from the detection position deviation of the position detection marks of at least three points, and subtracting the inclination component from the detection position deviation to calculate a correction detection position deviation, and
In the step of obtaining the height dependency of the electron beam, the electron beam incident angle is measured in an electron beam exposure apparatus that calculates the height dependency of the electron beam from the correlation between the correction height distribution and the correction detection position. Method. An electron beam generator for generating an electron beam; an electron beam shaping means for shaping the electron beam; an electron beam converging means for converging the electron beam on a sample surface; and an electron beam deflecting means for deflecting the electron beam. Including an electro-optic column,
Sample moving means for moving the sample in a plane perpendicular to the electron beam;
An exposure method for exposing a pattern on a wafer having a height distribution using an electron beam exposure apparatus comprising a control means for controlling the electron optical column and the sample moving means,
Measuring a distribution of incident angles of the electron beam on the sample by the method according to claim 1 ;
Measuring the height distribution of the sample;
Selecting several chips from the chips on the sample and detecting the position of the alignment mark of the selected chip by the electron beam;
The incident angle and height in the alignment mark are calculated from the incident angle distribution and the height distribution, the positional deviation due to the incident angle and height is calculated, and the position is determined from the detected position of the alignment mark. Subtracting the deviation and calculating the height correction mark position;
Obtaining a chip array grid on the sample based on the height correction mark position,
An exposure method in an electron beam exposure apparatus, wherein a pattern is exposed on a wafer while correcting a positional deviation at an exposure position from the distribution of incident angles and the height distribution according to the chip array grating.

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