JP2003007596A - Method and device of electron beam proximity exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct transfer magnification easily and accurately when the magnification of a mask and a wafer is varied due to expansion/contraction of a wafer. SOLUTION: In the electron beam proximity exposure method, a mask 32 is disposed in proximity to a wafer 44 and a mask pattern formed on the mask 32 is transferred to a resist layer on the wafer 44 by scanning the mask 32 with an electron beam. The mask 32 is aligned with a specified chip on the wafer 44 utilizing three microscope imaging units AX1, AY1 and AX2, distances Lx and Ly between specified chips are determined from the moving amount of a θXY stage 70 at the time of alignment and then current expansion/ contraction rate of the wafer 44 is measured in the x direction and y direction. Based on the expansion/contraction rate measured at the time of alignment, incident angle of an electron beam to the mask pattern is controlled thus correcting the transfer magnification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam proximity exposure method and apparatus, and more particularly to an electron beam for transferring a mask pattern of a mask arranged in proximity to a semiconductor wafer to a resist layer on the wafer at an equal size by using the electron beam. The present invention relates to a proximity exposure method and apparatus.

[0002]

2. Description of the Related Art Conventionally, an electron beam proximity exposure apparatus of this type has been disclosed in US Pat. No. 5,831,272 (corresponding to Japanese Patent No. 2951947).

FIG. 17 is a diagram showing the basic construction of the electron beam proximity exposure apparatus. This electron beam proximity exposure apparatus 1
0 is an electron beam source 14 that mainly generates an electron beam 15, an electron gun 12 that includes a lens 16 that makes the electron beam 15 a parallel beam, and a shaping aperture 18, and a main deflector 2.
2, 24 and sub-deflectors 26, 28, and is composed of a scanning means 20 for scanning an electron beam in parallel with the optical axis, and a mask 30. The mask 30 is arranged so as to be close to the wafer 40 having a resist layer 42 formed on the surface thereof (with a gap of 50 μm). In this state, when the mask 30 is vertically irradiated with an electron beam, the mask 30
The resist layer 42 on the wafer 40 is irradiated with the electron beam that has passed through the mask pattern.

The scanning means 20 also controls the deflection of the electron beam 15 so that the electron beam 15 scans the entire surface of the mask 30, as shown in FIG. As a result, the mask pattern of the mask 30 is transferred to the resist layer 42 on the wafer 40 at the same size.

This electron beam proximity exposure apparatus 10 is shown in FIG.
As shown in FIG. 9, it is provided in the vacuum chamber 50.
Further, in the vacuum chamber 50, the electrostatic chuck 60 for adsorbing the wafer 40, and the wafer 40 adsorbed by the electrostatic chuck 60 are moved in the horizontal two-axis directions and rotated in the horizontal plane. A θXY stage 70 is provided for this purpose. The θXY stage 70 moves the wafer 40 by a predetermined amount each time the mask pattern transfer at the same size is completed, and thereby a plurality of mask patterns can be transferred onto one wafer 40. In FIG. 19, reference numeral 80 is a conduction pin that is pressed against the upper surface of the wafer 40 to keep the wafer 40 conductive.

By the way, the wafer is exposed a plurality of times by using a plurality of masks having different mask patterns, thereby forming an integrated circuit. Then, at the time of exposing each mask pattern, it is necessary to relatively position the mask and the wafer so that the mask pattern to be exposed has a predetermined positional relationship with the already exposed mask pattern.

However, even if the mask and the wafer are accurately positioned, there is a problem that the mask patterns to be exposed are misaligned when the wafer expands and contracts with respect to a design value through an exposure process or the like. is there.

In order to solve this problem, a magnification correction amount detection method for obtaining the magnification correction amount between the mask and the wafer has been proposed (Japanese Patent Laid-Open No. 2000-353647). This Japanese Patent Application Laid-Open No. 2000-353647 discloses a method of arranging a mask in the vicinity of a wafer and exposing a mask pattern on the wafer by X-ray exposure. Further, in the magnification correction, the mask is locally heated to heat the mask. It is disclosed that the mask is deformed or a stress is applied to the mask from the outside to deform the mask.

[0009]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
When the mask is deformed by heat or an external force to correct the magnification between the mask and the wafer as described in JP-A-000-353647, the mask can be accurately deformed independently in the x-axis direction and the y-axis direction. It is difficult, and it is necessary to confirm the degree of deformation of the mask, and there is a problem that magnification correction cannot be performed easily.

The present invention has been made in view of the above circumstances, and the transfer magnification is set so that the mask patterns exposed on the wafer do not shift even if the magnification of the mask and the wafer change due to expansion and contraction of the wafer. It is an object of the present invention to provide an electron beam proximity exposure method and apparatus that can perform correction, and particularly can easily and accurately correct the transfer magnification.

[0011]

In order to achieve the above object, the invention according to claim 1 of the present application is a mask formed on a mask by arranging the mask close to a wafer and scanning the mask with an electron beam. In an electron beam proximity exposure method for transferring a pattern to a resist layer on the wafer, a step of measuring expansion / contraction ratios of a current wafer in the x direction and the y direction based on the wafer at a predetermined step; During exposure of the wafer, the x-direction and the y-direction are proportional to the expansion and contraction rates of the wafer in the x-direction and the y-direction.
The electron to the mask pattern based on the expansion and contraction rates of the wafer in the x and y directions, the distance value between the wafer and the mask, and the scanning position of the electron beam on the mask in order to change the transfer magnification in the direction. Controlling the angle of incidence of the beam.

That is, the expansion and contraction rates of the current wafer in the x and y directions are measured with reference to the wafer in a predetermined process (pre-process and design), and the mask pattern is transferred according to the expansion / contraction ratio. The transfer magnification is changed for each of the x direction and the y direction. Then, the transfer magnification is changed by controlling the incident angle of the electron beam to the mask pattern. That is, since the position of the mask pattern transferred onto the wafer varies depending on the incident angle of the electron beam on the mask pattern, minute magnification correction can be performed by changing the incident angle according to the scanning position of the electron beam on the mask. it can.

The step of measuring the mask distortion of the mask and controlling the incident angle of the electron beam as described in claim 2 of the present application is to change the transfer magnification and to correct the measured mask distortion. The incident angle of the electron beam to the mask pattern is controlled based on the expansion and contraction rates of the wafer in the x and y directions, the mask distortion, the distance value between the wafer and the mask, and the scanning position of the electron beam on the mask. It is characterized by doing. That is, by controlling the incident angle of the electron beam, the mask distortion is corrected simultaneously with the magnification correction of the wafer and the mask.

As described in claim 3 of the present application, a mask mark for alignment is provided on the mask, and the first chip formed on the wafer is separated from the first chip in the x direction. The step of measuring the expansion / contraction rate by providing a wafer mark for alignment corresponding to the mask mark on each of the second chip and the third chip spaced in the y-direction, and measuring the expansion / contraction ratio A first position in which the wafer and the mask are relatively moved in the x and y directions so that the wafer mark of the upper first chip has a predetermined positional relationship, and are relatively rotated in the xy plane. In the aligning step, the wafer and the mask are relatively x-positioned so that the mask mark of the mask and the wafer mark of the second chip on the wafer have a predetermined positional relationship. A second alignment step of moving in the direction and the y direction, and the wafer after the alignment in the first alignment step is completed and before the alignment in the second alignment step is completed. Measuring a first distance traveled relative to the mask,
The measured first movement distance, the first tip and the second
The step of obtaining the expansion / contraction ratio of the wafer in the x direction based on the distance to the chip in the predetermined process, and the mask mark of the mask and the wafer mark of the third chip on the wafer have predetermined positions. A third step of moving the wafer and the mask relative to each other in the x-direction and the y-direction so that they have a relationship with each other.
Second alignment step and the second alignment step of the first alignment step, and then the second relative alignment of the wafer and the mask until the alignment step of the third alignment step is completed. The step of measuring the moving distance, and the expansion / contraction ratio of the wafer in the y direction are obtained based on the measured second moving distance and the distance between the first chip and the third chip during the predetermined process. It is characterized by comprising steps and.

That is, when the mask mark of the mask and the wafer marks of the first, second and third chips on the wafer are sequentially aligned, the moving distance between the respective chips is measured, and the measured movement is performed. The expansion and contraction rates of the wafer in the x direction and the y direction are calculated from the distance and the reference distance between the chips (distance in a predetermined process).

The mask mark has a positional deviation in the x direction between the wafer and the mask and a y mark as described in claim 4 of the present application.
The first and second mask marks for detecting the positional deviation in the direction, and the first and second mask marks are provided at different positions, and the positional deviation in the x direction between the wafer and the mask or the y direction A third mask mark for detecting a positional deviation, and the wafer mark is in the x direction between the wafer and the mask based on the positional relationship between the first, second and third mask marks. The first and second wafer marks for detecting the positional deviation and the positional deviation in the y direction are provided at different positions from the first or second wafer mark, and the positional deviation between the wafer and the mask in the x direction. Or a third wafer mark for detecting displacement in the y direction,
First imaging means for simultaneously imaging the first mask mark and the first wafer mark; second imaging means for simultaneously imaging the second mask mark and the second wafer mark; Third masking means for simultaneously picking up the third mask mark and the third wafer mark are provided, and the first alignment step includes each image obtained from the first, second and third image pickup means. The wafer and the mask are relative to each other so that the positional deviations of the first, second and third mask marks and the first, second and third wafer marks detected based on the signals become zero. To the x direction and the y direction, and relatively rotate in the xy plane,
In the second and third alignment steps, the first and second mask marks and the first and second wafers detected based on the respective image signals obtained from the first and second image pickup means. It is characterized in that the wafer and the mask are moved relative to each other so that the positional deviation from the mark becomes zero.

According to a fifth aspect of the present invention, a mask mark for alignment is provided on the mask, and the first chip formed on the wafer is separated from the first chip in the x direction. A wafer mark for alignment corresponding to the mask mark on the second chip, the third chip formed on the wafer, and the fourth chip separated in the y direction from the third chip. And in the step of measuring the expansion / contraction rate, the wafer and the mask are relatively moved in the x direction so that the mask mark of the mask and the wafer mark of the first chip on the wafer have a predetermined positional relationship. And a first alignment step of moving in the y direction and relatively rotating in the xy plane, a mask mark of the mask and a wafer mark of the second chip on the wafer. After the second alignment step in which the wafer and the mask are relatively moved in the x direction and the y direction so as to have a predetermined positional relationship and the alignment in the first alignment step are finished, Measuring a relative first movement distance between the wafer and the mask until the alignment in the second alignment step is completed, the measured first movement distance, and the first chip The step of obtaining the expansion / contraction ratio of the wafer in the x direction based on the distance from the second chip in the predetermined process, the mask mark of the mask, and the wafer mark of the third chip on the wafer are predetermined. Third, the wafer and the mask are relatively moved in the x and y directions so as to be in the positional relationship of 3 and relatively rotated in the xy plane.
And the relative movement of the wafer and the mask in the x and y directions so that the mask mark of the mask and the wafer mark of the fourth chip on the wafer have a predetermined positional relationship. After the alignment in the fourth alignment step and the alignment in the third alignment step are completed, the relative alignment between the wafer and the mask is completed until the alignment in the fourth alignment step is completed. The step of measuring the movement distance of 2 and the expansion / contraction ratio of the wafer in the y direction based on the measured second movement distance and the distance between the third chip and the fourth chip during the predetermined process. And the step of obtaining.

That is, in claims 3 and 4, the three first,
When the second chip and the third chip are aligned with each other, the moving distance between the chips is measured to obtain the expansion / contraction ratios of the wafer in the x direction and the y direction.
When the first and second chips spaced apart from each other in the direction are aligned, the moving distance between the chips is measured to obtain the expansion / contraction rate of the wafer in the x direction. Similarly, the third and fourth separated chips are separated from each other in the y direction. The difference is that the expansion / contraction ratio in the y direction of the wafer is obtained by measuring the moving distance between the chips when the chips are aligned.

According to a sixth aspect of the present invention, the mask mark includes first and second mask marks for detecting a positional deviation between the wafer and the mask in the x direction and a positional deviation in the y direction. A third mask mark which is provided at a position different from that of the first or second mask mark and which detects a positional deviation between the wafer and the mask in the x direction or a positional deviation in the y direction. Is the first and second
And first and second wafer marks for detecting the positional deviation between the wafer and the mask in the x-direction and the positional deviation in the y-direction based on the positional relationship with the third mask mark, and the first or the second wafer mark. It is provided at a position different from the second wafer mark,
A third wafer mark for detecting a positional deviation between the wafer and the mask in the x-direction or a positional deviation in the y-direction, and imaging the first mask mark and the first wafer mark at the same time. No. 1 imaging unit, second imaging unit for simultaneously imaging the second mask mark and second wafer mark, and third imaging unit for simultaneously imaging the third mask mark and third wafer mark. Image pickup means is provided, and the first and third alignment steps are performed on the basis of the image signals obtained from the first, second and third image pickup means, and are detected based on the image signals. The wafer and the mask are moved relative to each other so that the misalignment between the third mask mark and the first, second and third wafer marks becomes zero.
Direction and y direction and relatively rotate in the xy plane, and the second and fourth alignment steps are detected based on each image signal obtained from the first and second image pickup means. The wafer and the mask are moved relative to each other so that the positional deviation between the first and second mask marks and the first and second wafer marks becomes zero.
It is characterized in that it is moved in the y-direction and the y-direction.

According to claim 7 of the present application, first and second mask marks for respectively detecting two positional deviations in the x direction between the mask and the chips formed on the wafer, and in the y direction. A third mask mark and a fourth mask mark for respectively detecting two positional deviations are provided on the mask, and the wafer is separated from the wafer based on the positional relationship with the first, second, third, and fourth mask marks. The wafer is provided with first, second, third and fourth wafer marks for detecting two positional deviations in the x direction and two positional deviations in the y direction with respect to the chip, and the first mask mark. And a first wafer mark at the same time, a first image pickup means, a second image pickup means for simultaneously picking up the second mask mark and the second wafer mark, a third mask mark and a third wafer mark Simultaneously with 3 wafer marks Providing a third image pickup means for picking up an image and a fourth image pickup means for picking up the fourth mask mark and the fourth wafer mark at the same time, the step of measuring the expansion / contraction rate includes the first and second steps. And the positional deviation between the first, second and third wafer marks and the first, second and third wafer marks detected based on the respective image signals obtained from the third and third image pickup means becomes zero. So that the wafer and the mask are relatively moved in the x direction and the y direction and relatively rotated in the xy plane, and the alignment in the first alignment step is performed. After the end, the y of the chip is detected from the positional deviation between the fourth mask mark and the fourth wafer mark detected based on the image signal obtained from the fourth image pickup means.
A step of obtaining an expansion / contraction ratio in the direction, and the first, third and fourth mask marks and the first mask mark detected based on the respective image signals obtained from the first, third and fourth image pickup means,
A second position in which the wafer and the mask are relatively moved in the x-direction and the y-direction so that the positional deviations from the third and fourth wafer marks are zero respectively, and are relatively rotated in the xy plane. After the alignment step and the alignment in the second alignment step are completed, the second mask mark and the second wafer mark detected based on the image signal obtained from the second imaging unit And a step of obtaining the expansion / contraction ratio of the chip in the x direction from the positional deviation of.

That is, in claims 3 to 6, the expansion and contraction ratios of the wafer in the x and y directions are obtained, but in claim 7, the mask pattern is transferred by using four image pickup means. For each chip unit, x of that chip
The expansion and contraction rates in the direction and the y direction are obtained.

As described in claim 8 of the present application, the optical member facing the mask of the imaging means has a conductive thin film deposited on the surface thereof, and the conductive thin film is grounded. There is. Further, as described in claim 9 of the present application, a shutter mechanism is provided on the front surface of the optical member of the image pickup means, the shutter mechanism is opened at the time of alignment, and electrons or secondary electrons scattered at the time of transfer by the electron beam are It is characterized in that the shutter mechanism is closed so that the optical member of the imaging means is not charged.

The invention according to claim 10 of the present application is an electron beam for transferring a mask pattern formed on a mask to a resist layer on the wafer by disposing the mask close to the wafer and scanning the mask with the electron beam. In the proximity exposure apparatus, an image pickup unit that simultaneously takes an image of a mask mark for alignment provided on the mask and a wafer mark for alignment provided on the wafer, and an image signal output from the image pickup unit. Detection means for detecting a positional deviation between the mask mark and the wafer mark based on the detection means, and means for relatively aligning the mask and the wafer so that the positional deviation becomes zero based on the detection output of the detection means. And a conductive thin film is deposited on the surface of the optical member of the image pickup means, and the conductive thin film is grounded. It is characterized in Rukoto.

The conductive thin film is a tin oxide film or an indium tin oxide film as set forth in claim 11 of the present application.

The invention according to claim 12 is an electron beam for transferring a mask pattern formed on a mask to a resist layer on the wafer by arranging the mask close to the wafer and scanning the mask with the electron beam. In the proximity exposure apparatus, an image pickup unit that simultaneously takes an image of a mask mark for alignment provided on the mask and a wafer mark for alignment provided on the wafer, and an image signal output from the image pickup unit. Detection means for detecting a positional deviation between the mask mark and the wafer mark based on the detection means, and means for relatively aligning the mask and the wafer so that the positional deviation becomes zero based on the detection output of the detection means. And the imaging means is characterized in that the electrons or secondary electrons scattered at the time of transfer by the electron beam are
It is characterized in that it has a shutter mechanism for shielding the optical member of the image pickup means from being charged.

That is, in the eighth to twelfth aspects of the present invention, the optical member is made conductive so that the electrons or secondary electrons scattered at the time of transfer by the electron beam are not charged to the optical member of the image pickup means, or are shielded by the shutter mechanism. ing. This prevents electrons from being charged in the optical member of the image pickup means arranged near the mask, and prevents the electron beam from being bent by the Coulomb force.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an electron beam proximity exposure method and apparatus according to the present invention will be described below with reference to the accompanying drawings. [First Embodiment] FIGS. 1 and 2 are a top view and a side view of a transfer portion of an electron beam proximity exposure apparatus according to the present invention, respectively.

As shown in these drawings, the electron beam proximity exposure apparatus is provided with three microscope image pickup devices AX1, AY1 and AX2 facing the mask 32.
These microscope image pickup devices AX1, AY1, and AX2 are arranged so that the photographing optical axis is oblique to the mask surface so as not to block the electron beam during exposure with the electron beam. Since the main configuration of the electron beam proximity exposure apparatus is the same as that shown in FIGS. 17 to 19, detailed description thereof will be omitted.

FIG. 3 is an enlarged top view of the transfer portion of the electron beam proximity exposure apparatus.

In the figure, 44 is the θXY stage 7.
It is a wafer that has been attracted by the electrostatic chuck 60 on 0.

On this wafer 44, a wafer mark M _WX for positioning each chip of the wafer 44 in the x-axis direction.
And a wafer mark M _WY for positioning in the y-axis direction
And are provided outside the area where the chip is formed.

On the other hand, on the mask 32, a mask pattern is formed in a region indicated by a broken line, and in the x direction between the mask 32 and the wafer 44 in relation to the wafer marks M _WX and M _WY outside the region indicated by the broken line. , Y direction, and three mask marks M _MX1 , M _MX2 , and M _MY for detecting the displacement in the rotation direction of the xy plane are provided.

The details of the wafer mark and the mask mark will be described with reference to FIGS. 4 and 5.

FIG. 4 is an enlarged view of a portion indicated by reference character A in FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 of FIG. As shown in FIG. 4, the mask 32 has a mask mark M _MX1.
Are formed so that the wafer marks M _WX and M _WX therebelow can be seen through the mask 32.

The mask mark M _MX1 formed on the mask 32 is composed of 5 × 3 small openings, while the wafer mark M _WX is composed of 14 × 3 convex portions. (See FIGS. 4 and 5).

Next, the microscope image pickup device AX1 will be described.

FIG. 6 shows an outline of the microscope image pickup device AX1. As shown in the figure, the microscope image pickup device AX1 is arranged so that the incident angle of the optical axis with respect to the mask 32 arranged horizontally becomes a predetermined angle α.

A cover glass 91 is attached to the front surface of the microscope objective lens 90. This cover glass 9
A conductive thin film 91A is vapor-deposited on the surface of No. 1 and the conductive thin film 91A is grounded via the conductive holding member 92 and the casing of the microscope image pickup device AX1. This prevents electrons or secondary electrons scattered during transfer by the electron beam from charging the surface of the cover glass 91.

A tin oxide film or an indium tin oxide film (ITO) is used as the conductive thin film 91A. Further, in this embodiment, the conductive thin film 91A is vapor-deposited on the surface of the cover glass 91, but in the case of a microscope image pickup apparatus in which the cover glass is not provided, the surface of the microscope objective lens 90 is electrically conductive. A conductive thin film is vapor deposited and the conductive thin film is grounded.

Further, a mechanical shutter mechanism is provided in place of the conductive thin film 91A, the shutter mechanism is closed at the time of transfer by the electron beam to shield the optical member of the microscope image pickup device, and the shutter mechanism is opened at the time of image pickup. May be. Needless to say, the shutter mechanism in this case is one that is not charged with electrons.

Illumination means is provided inside the microscope image pickup device AX1. That is, the illumination means is a white light source 93, a lens 94, a reflection mirror 95, and a half mirror 9.
The white illumination light emitted from the white light source 93 is made into a substantially parallel light by the lens 94, and the mask 32 and the wafer are passed through the reflection mirror 95, the half mirror 96, the objective lens 90 and the cover glass 91. Illuminate 44.

The scattered light at the mask mark of the mask 32 and the wafer mark of the wafer 44 illuminated in this way is incident on the image pickup section 97 via the objective lens 90 and the half mirror 96 and is picked up.

The other microscope image pickup devices AY1 and AX2 have the same structure as the microscope image pickup device AX1.

As shown in FIG. 7A, the mask mark M _MX
As for the wafer mark M _WX , the length of each mark and the incident angle α of the photographing optical axis are determined so that a part of the mark is located on the focal plane F of the microscope image pickup apparatus. Incidentally, FIG.
In (A), P is the regular reflection light of the white illumination light, Q and R are the scattered light of the white illumination light at the mask mark M _MX and the wafer mark M _WX , and G is the distance between the mask 32 and the wafer 44. is there.

FIG. 7B is an image showing a state in which scattered light Q, R of white illumination light is imaged by the microscope image pickup device.

Next, a method of detecting the deviation between the mask and the wafer based on the mask mark and the wafer mark imaged as described above will be described.

As shown in FIG. 8A, a focused portion (a portion surrounded by a frame) is continuously extracted in the x direction from the image of the mask mark and the wafer mark imaged. FIG. 8B shows the brightness level at each position in the x direction of the image thus extracted.

Here, as shown in FIG. 8B, the center peak position of the three peaks is obtained for the brightness levels corresponding to the two mask marks M _MX and one wafer mark M _WX . Distance between peaks x ₁ , x ₂
Ask for. Then, the mask mark M _MX and the wafer mark M
The positional deviation amount Δx in the x direction and _WX is calculated by the following equation:

[0049]

It can be obtained by Δx = (x ₁ −x ₂ ) / 2.

It should be noted that the microscope image pickup devices AX1 and AX2 can detect two positional deviation amounts of the mask 32 and the wafer 44 in the x direction, and the microscope image pickup device AY1 can detect one position in the y direction of the mask 32 and the wafer 44. The amount of deviation can be detected.

Next, a method of measuring the expansion and contraction rates of the wafer in the x and y directions will be described.

As shown in FIG. 3, first, a chip (hereinafter referred to as a first chip) in the upper left corner of the wafer 44 and the mask 3 are formed.
Position 2 and. This positioning is performed by moving the θXY stage 70 so that the positional deviation amounts detected by the respective microscope image pickup devices AX1, AY1, and AX2 become zero at the same time.
Direction and y direction, and θX in the xy plane
This is performed by rotating the Y stage 70.
Although the θXY stage 70 is rotated in this embodiment, the mask 32 may be rotated, or the mask 32 may be moved in the x and y directions instead of moving the wafer 44. You may let me.

When the positioning of the mask 32 and the first chip is completed as described above, the chip in the upper right corner of the wafer 44 (hereinafter, referred to as the second chip) and the mask 32 are subsequently formed.
Position and. The positioning at this time is performed based on the amount of positional deviation detected by each of the microscope image pickup devices AX1 and AY1, and the rotation direction is not adjusted.

Next, the distance L _x between the first chip and the second chip is obtained. This distance L _x is defined as follows: where the moving amount in the x direction of the θXY stage 70 moved from the positioning of the first chip to the positioning of the second chip is x ₂ , and the moving amount in the y direction is y ₂ . The following equation,

[0055]

## EQU2 ## It can be obtained by L _x = √ (x ₂ ² + y ₂ ² ). The movement amount x ₂ , y
₂ is measured by two laser interferometers that detect the amount of movement of the θXY stage 70 in the x and y directions. That is, the readings of the two laser interferometers when the first chip is positioned are (0, 0), and the readings of the two laser interferometers when the second chip is positioned (x ₂ ,
The movement amounts x ₂ and y ₂ are measured from y ₂ ).

On the other hand, when the reference distance between the first chip and the second chip is L _ref , the expansion / contraction amount δ _x of the wafer 44 in the x direction is given by the following equation:

[0057]

## EQU3 ## δ _x = L _x −L _ref , and the expansion / contraction ratio ε _{x in the} x direction is given by

[0058]

## EQU4 ## ε _x = (L _x −L _ref ) / L _ref .

The reference distance L _ref is a length determined in a previous step or when a wafer mark is formed or a length determined as a design dimension.

If the θXY stage 70 has a posture error due to movement (especially an error in the yaw direction),
It is preferable that the laser interferometer is composed of three axes (for example, X, Y1, and Y2), the angle changed in the yaw direction is measured, and the error due to yaw is removed from the value of L _x .

Similarly, the expansion / contraction rate ε _Y of the wafer 44 in the y direction can also be obtained. In this case, the chip at the lower left corner of the wafer 44 (hereinafter referred to as the third chip) and the mask 3
Position 2 and. This positioning is performed based on the amount of positional deviation detected by the microscope image pickup devices AX1 and AY1 similarly to the positioning of the second chip, and the rotation direction is not adjusted. Then, the distance between the first chip and the third chip is measured from the reading values (x ₃ , y ₃ ) of the two laser interferometers when the third chip is positioned.

In the above embodiment, when the three chips (first, second and third chips) are positioned, the moving distance between the chips is measured to measure the wafer in the x and y directions. The expansion / contraction ratio was calculated, but as shown in FIG.
It is also possible to obtain the expansion / contraction ratios of the wafer in the x-direction and the y-direction by measuring the moving distance between the respective chips when the four chips 1 to 4 are positioned.

That is, as shown in FIG. 9, the moving distance Lx between the chips 1 and 2 when the chips 1 and 2 spaced apart in the x-direction are positioned on the wafer 44 is measured to measure the wafer. The expansion / contraction ratio in the x direction is obtained, and similarly, the moving distance Ly between the chips 3 and 4 when the chips 3 and 4 respectively spaced in the y direction are positioned on the wafer 44 is measured to measure the wafer. Obtain the expansion / contraction rate in the y direction.

The positioning of the chips 1 and 3 is performed by the θXY stage 7 so that the positional deviation amounts detected by the respective microscope image pickup devices AX1, AY1 and AX2 become zero at the same time.
By moving 0 in the x and y directions, and rotating the θXY stage 70 in the xy plane,
The positioning of the chips 2 and 4 is performed by the microscope image pickup devices AX1 and AX.
It is performed based on the amount of positional deviation detected by Y1, and the rotation direction is not adjusted.

Further, when positioning the chips 1 and 3, θ
Although the θ is adjusted by rotating the XY stage 70, the θ may be adjusted by rotating the mask side. In this case, when the chips 2 and 4 are positioned, the mask is not rotated (that is, the rotational position of the mask whose θ is adjusted is maintained), and the alignment in the x direction and the y direction is performed.

FIG. 10 is a block diagram showing an embodiment of the control unit of the electron beam proximity exposure apparatus according to the present invention.

In the figure, a central processing unit (CPU) 1
Reference numeral 00 denotes an overall control of the entire apparatus, which performs the processing for obtaining the expansion and contraction rates of the wafer in the x and y directions as described above, the wafer positioning control, the electron beam deflection control during exposure, and the like. Three microscope image pickup devices AX1, AY1,
Each image signal obtained by the image pickup by the AX2 is added to the signal processing circuit 102. The signal processing circuit 102 calculates three positional deviation amounts of the mask mark and the wafer mark based on the input image signals.

The CPU 100 causes the θXY stage 70 to move in the x direction via the stage drive circuit 104 so that the three positional deviation amounts input from the signal processing circuit 102 become zero.
While being moved in the y direction, the θXY stage 70 is rotated in the xy plane, thereby performing highly accurate positioning (fine alignment) of the wafer.

When obtaining the expansion and contraction rates of the wafer in the x and y directions, the CPU 100 performs fine alignment of the first chip, the second chip and the third chip of the wafer as described with reference to FIG. , Laser interferometers L _X , L after fine alignment of the second and third chips
The distance between each chip is calculated from the _Y reading values (x ₂ , y ₂ ) and (x ₃ , y ₃ ), and the expansion and contraction of the wafer in the x and y directions based on the measured distance and the reference distance. Find the rate.

Further, the CPU 100 supplies the correction data corresponding to the expansion / contraction rate of the wafer together with the deflection amount data when scanning the mask to the digital arithmetic circuit 106, and the digital arithmetic circuit 106 scans the mask based on the deflection amount data. Output to the main DAC / AMP 108 to change the transfer magnification in the x-direction and the y-direction in proportion to the expansion and contraction rates of the wafer in the x-direction and the y-direction based on the correction data. A digital signal for correcting the mask distortion is output to the sub DAC / AMP 110.

The main DAC / AMP 108 converts the input digital signal into an analog signal, amplifies it, and outputs it to the main deflectors 22 and 24 shown in FIG. As a result, the electron beam 15 is deflected so as to scan the entire surface of the mask 30 as shown in FIG. 18 while maintaining the state of being parallel to the optical axis.

The sub DAC / AMP 110 converts the input digital signal into an analog signal and then amplifies it.
This is output to the sub deflectors 26 and 28 shown in FIG. As a result, the incident angle of the electron beam 15 on the mask 32 is controlled as shown in FIG.

Now, as shown in FIG.
The incident angle of the light on the mask 32 is α, the mask 32 and the wafer 4
4 is G, the shift amount δ of the transfer position of the mask pattern due to the incident angle α is

[0074]

[Expression 5] δ = G · tan α In FIG. 11, the mask pattern has a shift amount δ.
However, it is transferred to a position deviated from the regular position.

Therefore, the transfer magnification can be changed by changing the incident angle α according to the scanning position of the electron beam. As for the incident angle α, the incident angle α is set to 0 at the center of the mask, and the incident angle α is increased as the distance from the center of the mask increases.

FIG. 12 is a flow chart showing the operation procedure of the electron beam proximity exposure method according to the present invention.

As shown in the figure, first, a mask is loaded into the electron beam proximity exposure apparatus (step S10), the wafer is subsequently positioned on the electrostatic chuck 60 on the θXY stage 70, and then the electrostatic chuck 60 is used. The wafer is loaded by adsorption and fixation (step SS12). Then, the wafer is electrically connected by a conduction pin or the like so that the wafer is not charged with electrons (step S14).

Next, the height is detected by the z sensor for detecting the height of the wafer, the height of the wafer is adjusted (step S16), and then the rough alignment (course alignment) of the wafer is performed ( Step S18).

Subsequently, as described with reference to FIGS. 3 and 9, the expansion and contraction rates ε _x and ε _Y of the wafer in the x and y directions are measured (MA
G measurement (global) is performed (step S30), and a signal indicating the measured expansion / contraction ratios ε _x and ε _Y is output to the correction arithmetic circuit 106A. Then, the wafer is moved to the transfer position (step S20).

Next, the distance between the mask and the wafer (GAP)
Is adjusted (step S22). As shown in FIG. 7A, the distance G between the mask and the wafer is determined by the intersection Q between the image plane of the microscope image pickup device and the mask mark M _MX and the wafer mark M _wx.
A line segment QR with an intersection R with the line R is obtained based on the photographed image, and from the line segment QR and the incident angle α of the photographing optical axis, the following equation,

[0081]

## EQU6 ## It can be obtained by G = QR.sin α. For details, see JP 2000
It is disclosed in Japanese Patent Publication No. 356511. The method of measuring the gap G is not limited to this embodiment.

The gap G is adjusted so that the gap G measured as described above has a predetermined value (for example, 50 μm).
The value of the interval G (interval value) is added to the correction calculation circuit 106A. The correction arithmetic circuit 106A corresponds to a circuit that controls the deflection of the sub deflectors 26 and 28 in the digital arithmetic circuit 106 shown in FIG.

Then, the three microscope image pickup devices AX1 and A
After the mask and the chip on the wafer are accurately positioned (fine alignment) using Y1 and AX2 (step S24), the mask pattern is transferred onto the wafer by the electron beam (step S26).

At the time of this transfer, the correction calculation circuit 106A changes the transfer magnification based on the expansion and contraction rates ε _x and ε _Y of the wafer, and controls the incident angle of the electron beam to the mask pattern so as to correct the mask distortion ( Tilt correction).
The correction calculation circuit 106A is input with data indicating the mask distortion measured in advance in step S32.
The correction arithmetic circuit 106A, for example, when the mask distortion shown in FIG. 13A is inputted, the electron beam is transferred so that the mask pattern shown in FIG. 13B without the mask distortion is transferred. Tilt correction.

When the transfer of the mask pattern onto the wafer is completed, the wafer is unloaded (step S28). [Second Embodiment] FIG. 14 is an enlarged top view of a transfer portion of a second embodiment of the electron beam proximity exposure apparatus according to the present invention. The same parts as those of the first embodiment shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 14, in this electron beam proximity exposure apparatus, four microscope image pickup devices AX1, AY1,
AX2 and AY2 are provided. Also, the wafer 44 '
_Are four sets of wafer marks M _WX1, M for positioning each chip of the wafer 44 'and measuring the expansion / contraction rate of each chip.
_WX2, M _{WY1, and} M _WY2 (see FIG. 15) are provided outside the area where the chip is formed.

[0087] On the other hand, the mask in relation to the mask 32 'is formed with a mask pattern in a region indicated by a broken line, and the wafer mark _{M WX1, M WX2, M WY1} , M WY2 outside the region shown by a broken line 32 'and the wafer 44' are deviated in the x direction and the y direction, and deviated in the rotation direction of the xy plane, and the x of the chip.
Four mask marks M _MX1, M _MX2, M _{MY1, and} M _MY2 for detecting the expansion and contraction rates in the y-direction and the y-direction are provided.

Next, a method of measuring the expansion / contraction ratios of the respective chips on the wafer in the x and y directions will be described.

When the expansion / contraction ratio of the chip is measured, the chip to be measured and the mask 32 'are positioned. When the expansion / contraction ratio of the chip in the y direction is measured, three microscope image pickup devices AX1, The θXY stage 70 is moved in the x direction and the y direction so that the positional deviation amounts detected by AY1 and AX2 become zero at the same time.
The θXY stage 70 is rotated in the y plane. In this embodiment, positioning marks are formed so that the center of the chip coincides with the center of the mask.

Then, the positional deviation amount Δy detected by the remaining microscope image pickup device AY2 is obtained. This positional deviation amount Δy is _{calculated by using} two wafer marks M _WY2 and a mask mark M.
_Assuming that each distance from _MY2 is y ₁ and y _{2 as} shown in FIG.

[0091]

It can be expressed by Δy = (y ₁ −y ₂ ) / 2. By dividing the amount of positional deviation Δy thus obtained by the reference length in the y direction from the center of the chip to the centers of the two wafer marks M _WY2 , the expansion / contraction ratio of the chip in the y direction can be obtained. it can.

Similarly, the expansion / contraction rate of the chip in the x direction is measured.
To determine the three microscope imaging devices AX1, AY
1, the amount of displacement detected by AY2 is
The θXY stage 70 in the x and y directions so that
While moving, the θXY stage 70 in the xy plane
Is rotated and detected by the remaining microscope imager AX2
The positional deviation amount Δx to be obtained is obtained. This positional deviation amount Δx
Is the two wafer marks M _WX2And mask mark M_MX2When
Each distance of x, as shown in FIG.₁, X₂Then,
The following equation,

[0093]

It can be expressed by Δx = (x ₁ −x ₂ ) / 2. By dividing the positional deviation amount Δx thus obtained by the reference length in the x direction from the center of the chip to the centers of the two wafer marks M _WX2 , the expansion / contraction rate of the chip in the x direction can be obtained. it can.

FIG. 16 is a flow chart showing the operation procedure of the electron beam proximity exposure method according to the present invention. Incidentally, FIG.
The same parts as 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As is clear from the flowchart shown in FIG. 16, in the second embodiment, step 3 for measuring the expansion / contraction ratio of the entire wafer (global) shown in FIG.
Instead of 0, step 40 of measuring the expansion / contraction ratio (MAG measurement (chip)) for each chip as described in FIG.
The difference is that it has. The positioning mark formed on the wafer or the mask is not limited to this embodiment.

[0096]

As described above, according to the present invention, it is possible to perform exposure so that the mask patterns exposed on the wafer do not shift even if the magnification of the mask and the wafer change due to expansion and contraction of the wafer. Especially, since the transfer magnification is corrected by controlling the incident angle of the electron beam to the mask, the transfer magnification can be corrected easily and accurately. If the mask has distortion, the mask distortion can be corrected simultaneously with the transfer magnification correction.

[Brief description of drawings]

FIG. 1 is a top view of a transfer section of an electron beam proximity exposure apparatus according to the present invention.

FIG. 2 is a side view of a transfer portion of the electron beam proximity exposure apparatus according to the present invention.

3 is an enlarged top view of a transfer portion of the electron beam proximity exposure apparatus shown in FIG.

FIG. 4 is an enlarged view of a main part of FIG.

5 is a sectional view taken along line 5-5 of FIG.

FIG. 6 is a schematic configuration diagram of a microscope image pickup device applied to the present invention.

FIG. 7 is a diagram used for explaining a method of detecting a positional deviation amount between a mask mark and a wafer mark by a microscope imaging device.

FIG. 8 is a diagram used for explaining a method of detecting a positional deviation amount between a mask mark and a wafer mark by a microscope imaging device.

FIG. 9 is a diagram used to explain another embodiment of the method for measuring the expansion / contraction rate of a wafer.

FIG. 10 is a block diagram showing an embodiment of a control unit of an electron beam proximity exposure apparatus according to the present invention.

FIG. 11 is a diagram showing how the electron beam transfer position is displaced by the sub-deflector.

FIG. 12 is a flowchart showing an operation procedure of an electron beam proximity exposure method according to the present invention.

FIG. 13 is a diagram used for explaining mask distortion correction.

FIG. 14 is a second electron beam proximity exposure apparatus according to the present invention.
The top view which expanded the transfer part of the embodiment of FIG.

FIG. 15 is a diagram used for explaining how to obtain the expansion / contraction rate for each chip.

FIG. 16 is a flowchart showing an operation procedure of the second embodiment of the electron beam proximity exposure method.

FIG. 17 is a basic configuration diagram of an electron beam proximity exposure apparatus to which the present invention is applied.

FIG. 18 is a diagram used for explaining scanning of a mask by an electron beam.

FIG. 19 is an overall configuration diagram of an electron beam proximity exposure apparatus to which the present invention is applied.

[Explanation of symbols]

15 ... Electron beam, 22, 24 ... Main deflector, 26, 28
... Sub-deflector, 32, 32 '... Mask, 44, 44' ... Wafer, 60 ... Electrostatic chuck, 70 ... θXY stage, 9
0 ... Microscope objective lens, 91 ... Cover glass, 91A ...
Conductive thin film, 92 ... Conductive holding member, 93 ... White light source, 97 ... Imaging unit, 100 ... Central processing unit (CPU),
102 ... Signal processing circuit, 104 ... Stage drive circuit, 1
06 ... Digital arithmetic circuit, 106A ... Correction arithmetic circuit, A
X1, AY1, AX2, AY2 ... Microscope imaging device,
_{M WX, M WY, M WX1} , M WX2, M WY1, M WY2 ... wafer _{mark, M MX, M MY, M} MX1, M MX2, M MY1, M MY2 ... mask mark, L _X, L _Y ... laser interference Total

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03F 7/20 521 G03F 9/00 H 9/00 H01J 37/305 B H01J 37/305 H01L 21/30 541M 541S (72) Inventor Tsuyoshi Miyatake 2-1-1 Yatocho, Nishi-Tokyo, Tokyo Sumitomo Heavy Industries, Ltd. Tanashi Factory F-term (reference) 2F069 AA03 AA68 BB15 EE20 EE22 GG04 GG07 GG13 GG64 HH30 MM03 MM23 NN08 PP02 2H097 AA03 BA10 CA16 GA45 KA03 KA12 KA13 KA29 LA10 5C034 BB10 5F056 AA22 AA25 AA26 CC03 FA03 FA06

Claims (12)

[Claims] 1. An electron beam proximity exposure method for transferring a mask pattern formed on a mask to a resist layer on the wafer by arranging the mask close to the wafer and scanning the mask with an electron beam. Measuring the expansion / contraction ratios of the current wafer in the x-direction and the y-direction based on the wafer during the process, and proportional to the expansion / contraction ratios of the wafer in the x-direction and the y-direction during the exposure of the wafer by the electron beam. In order to change the transfer magnification in the x direction and the y direction in accordance with the expansion / contraction ratio of the wafer in the x direction and the y direction, the distance value between the wafer and the mask, and the scanning position of the electron beam on the mask. Controlling the angle of incidence of the electron beam on the mask pattern, and the electron beam proximity exposure method. 2. The step of measuring the mask distortion of the mask and controlling the incident angle of the electron beam comprises changing the transfer magnification and correcting the measured mask distortion in the x direction and the y direction of the wafer. The angle of incidence of the electron beam on the mask pattern is controlled based on the expansion / contraction ratio in the direction, the mask distortion, the distance value between the wafer and the mask, and the scanning position of the electron beam on the mask. The electron beam proximity exposure method according to claim 1. 3. A mask mark for alignment is provided on the mask, and a first chip formed on the wafer and a second chip spaced from the first chip in the x direction.
And the third chip spaced apart in the y-direction are provided with wafer marks for alignment corresponding to the mask marks, and the step of measuring the expansion / contraction rate includes the mask marks of the mask and the wafer. A first alignment step in which the wafer and the mask are relatively moved in the x and y directions so as to have a predetermined positional relationship with the wafer mark of the first chip and relatively rotated in the xy plane. And a second position for relatively moving the wafer and the mask in the x and y directions so that the mask mark of the mask and the wafer mark of the second chip on the wafer have a predetermined positional relationship. After the alignment step and the alignment in the first alignment step are completed, until the alignment in the second alignment step is completed Measuring a relative first movement distance between the wafer and the mask, the measured first movement distance, the first chip and the second
The step of obtaining the expansion / contraction ratio of the wafer in the x direction based on the distance to the chip in the predetermined process, and the mask mark of the mask and the wafer mark of the third chip on the wafer have predetermined positions. A third step of moving the wafer and the mask relative to each other in the x-direction and the y-direction so that they have a relationship with each other.
Second alignment step and the second relative alignment between the wafer and the mask after the alignment in the first alignment step is completed and before the alignment in the third alignment step is completed. Measuring a moving distance, the measured second moving distance, the first tip and the third
3. The electron beam proximity exposure method according to claim 1, further comprising: a step of obtaining an expansion / contraction ratio of the wafer in the y direction based on a distance between the wafer and the chip during the predetermined process. 4. The mask marks are first and second mask marks for detecting a positional deviation between the wafer and the mask in the x direction and a positional deviation in the y direction, and the first or second mask. A third mask mark which is provided at a position different from the mark and detects a positional deviation in the x direction or a positional deviation in the y direction between the wafer and the mask, and the wafer mark includes the first and the first mask marks. First and second wafer marks for detecting a positional deviation between the wafer and the mask in the x direction and a positional deviation in the y direction based on the positional relationship between the second and third mask marks; A third wafer mark which is provided at a position different from that of the second wafer mark, and which detects a positional deviation in the x direction or a positional deviation in the y direction between the wafer and the mask, and the first mask mark And the first waferma Image pickup means for simultaneously picking up the second mask mark, the second wafer mark, and the third mask mark and the third wafer mark. And a third image pickup means for simultaneously picking up the image, and the first alignment step detects the first image based on each image signal obtained from the first, second and third image pickup means. Second and third mask marks and first,
The wafer and the mask are moved in the x and y directions relative to each other so that the positional deviations from the second and third wafer marks are zero, and the wafer and the mask are relatively rotated in the xy plane; And a third alignment step is performed for the first and second mask marks and the first and second wafer marks, which are detected based on the respective image signals obtained from the first and second imaging means. 4. The electron beam proximity exposure method according to claim 3, wherein the wafer and the mask are moved relative to each other so that the positional deviation becomes zero. 5. A mask mark for alignment is provided on the mask, and a first chip formed on the wafer and a second chip spaced from the first chip in the x direction.
Chip and a third chip formed on the wafer,
Providing a wafer mark for alignment corresponding to the mask mark on each of the fourth chip spaced in the y direction with respect to the third chip, and measuring the expansion / contraction rate, First, the wafer and the mask are relatively moved in the x and y directions so that the wafer mark of the first chip on the wafer has a predetermined positional relationship, and the wafer and the mask are relatively rotated in the xy plane. Aligning step, and moving the wafer and the mask relatively in the x direction and the y direction so that the mask mark of the mask and the wafer mark of the second chip on the wafer have a predetermined positional relationship. After the second alignment step and the alignment in the first alignment step are completed, the alignment in the second alignment step is completed. Measuring a relative first moving distance between the wafer and the mask, the measured first moving distance, the first chip and the second
Determining the expansion / contraction ratio of the wafer in the x direction based on the distance between the wafer and the chip in the predetermined process, and the mask mark of the mask and the wafer mark of the third chip on the wafer have predetermined positions. A third alignment step of relatively moving the wafer and the mask in the x and y directions so as to be in a relationship and relatively rotating in the xy plane; and a mask mark of the mask and the wafer. A fourth alignment step in which the wafer and the mask are relatively moved in the x direction and the y direction so that the wafer mark of the fourth chip has a predetermined positional relationship; and the third alignment step. After the alignment of the wafer is completed, the second relative movement distance between the wafer and the mask is measured until the alignment in the fourth alignment step is completed. And-up, the second moving distance between the third chip and the fourth was the measurement
3. The electron beam proximity exposure method according to claim 1, further comprising: a step of obtaining an expansion / contraction ratio of the wafer in the y direction based on a distance between the wafer and the chip during the predetermined process. 6. The mask marks are first and second mask marks for detecting a positional shift between the wafer and the mask in the x direction and a positional shift in the y direction, and the first or second mask. A third mask mark which is provided at a position different from the mark and detects a positional deviation in the x direction or a positional deviation in the y direction between the wafer and the mask, and the wafer mark includes the first and the first mask marks. First and second wafer marks for detecting a positional deviation between the wafer and the mask in the x direction and a positional deviation in the y direction based on the positional relationship between the second and third mask marks; A third wafer mark which is provided at a position different from that of the second wafer mark, and which detects a positional deviation in the x direction or a positional deviation in the y direction between the wafer and the mask, and the first mask mark And the first waferma Image pickup means for simultaneously picking up the second mask mark, the second wafer mark, and the third mask mark and the third wafer mark. And a third image pickup means for simultaneously picking up the image,
The positional deviations between the first, second and third wafer marks and the first, second and third wafer marks, which are detected based on the respective image signals obtained from the second and third image pickup means, respectively. The wafer and the mask are relatively moved in the x and y directions so as to be zero and relatively rotated in the xy plane, and the second and fourth alignment steps include the first and the second alignment steps. The wafer and the mask so that the positional deviations between the first and second mask marks and the first and second wafer marks, which are detected based on the respective image signals obtained from the second image pickup means, become zero. 6. The electron beam proximity exposure method according to claim 5, characterized in that is relatively moved in the x direction and the y direction. 7. A first and a second mask mark for respectively detecting two positional deviations in the x direction between the mask and a chip formed on the wafer, and two respective positional deviations in the y direction are detected. A third mask mark and a fourth mask mark are provided on the mask, and based on the positional relationship between the first, second, third and fourth mask marks, the wafer and the chip in the x direction Two
First, second, third and fourth wafer marks for detecting one positional deviation and two positional deviations in the y direction are provided on the wafer, and the first mask mark and the first wafer mark are provided. A first imaging unit that simultaneously images, a second imaging unit that simultaneously images the second mask mark and the second wafer mark, and an image of the third mask mark and the third wafer mark at the same time. And a fourth image capturing means for capturing the fourth mask mark and the fourth wafer mark at the same time, and the step of measuring the expansion / contraction ratio includes the first, second and The positional deviation between the first, second and third mask marks and the first, second and third wafer marks detected based on the respective image signals obtained from the third image pickup means becomes zero. And the wafer and mask x is moved relatively x-direction and y-direction
After the first alignment step of relatively rotating in the y plane and the alignment in the first alignment step are completed, detection is performed based on the image signal obtained from the fourth image pickup means. A step of obtaining an expansion / contraction ratio of the chip in the y direction from the positional deviation between the fourth mask mark and the fourth wafer mark, and based on each image signal obtained from the first, third and fourth image pickup means. The wafer and the mask are relatively moved in the x direction so that the positional deviations of the first, third and fourth mask marks and the first, third and fourth wafer marks detected by And move in the y direction and x
After the second alignment step of relatively rotating in the y plane and the alignment in the second alignment step are completed, detection is performed based on the image signal obtained from the second image pickup means. 3. The electron beam proximity exposure method according to claim 1, further comprising the step of obtaining an expansion / contraction ratio of the chip in the x direction from the positional shift between the second mask mark and the second wafer mark. 8. The electron beam proximity exposure method according to claim 4, 6 or 7, wherein a conductive thin film is vapor-deposited on the surface of the optical member of the imaging means facing the mask, and the conductive thin film is formed. An electron beam proximity exposure method characterized by being grounded. 9. The electron beam proximity exposure method according to claim 4, 6 or 7, wherein a shutter mechanism is provided on the front surface of the optical member of the image pickup means, the shutter mechanism is opened during the alignment, and the transfer is performed by the electron beam. An electron beam proximity exposure method characterized in that the shutter mechanism is closed so that scattered electrons or secondary electrons are not charged to the optical member of the imaging means. 10. An electron beam proximity exposure apparatus which transfers a mask pattern formed on a mask to a resist layer on the wafer by placing the mask close to the wafer and scanning the mask with an electron beam. Image pickup means for simultaneously picking up the alignment mask mark provided on the wafer and the alignment wafer mark provided on the wafer, and the mask mark and the wafer based on the image signal output from the image pickup means. The image pickup device further includes a detection unit that detects a positional deviation from the mark, and a unit that relatively aligns the mask and the wafer so that the positional deviation becomes zero based on a detection output of the detection unit. The optical member of the means is characterized in that a conductive thin film is vapor-deposited on its surface and the conductive thin film is grounded. Beam proximity exposure apparatus. 11. The electron beam proximity exposure apparatus according to claim 10, wherein the conductive thin film is a tin oxide film or an indium tin oxide film. 12. An electron beam proximity exposure apparatus, wherein a mask is arranged close to a wafer, and the mask pattern formed on the mask is transferred to a resist layer on the wafer by scanning the mask with an electron beam. Image pickup means for simultaneously picking up the alignment mask mark provided on the wafer and the alignment wafer mark provided on the wafer, and the mask mark and the wafer based on the image signal output from the image pickup means. The image pickup device further includes a detection unit that detects a positional deviation from the mark, and a unit that relatively aligns the mask and the wafer so that the positional deviation becomes zero based on a detection output of the detection unit. The means prevents the electrons or secondary electrons scattered during the transfer by the electron beam from charging the optical member of the imaging means. Electron beam proximity exposure apparatus characterized by having a shutter mechanism for 蔽.