JPH08227840A - Adjusting method and drawing method in charged-particle-line drawing apparatus - Google Patents

Abstract

PURPOSE: To facilitate the confirmation and the adjustment of Abbe's conditions and to perform drawing accurately by performing the position detection of a plurality of marks having different heights, which are arranged on a stage, after the movement of the stage, and adjusting the illuminating height of a laser beam in correspondence with the height of the mark where the value of the reproducibility of the mark position is minimum. CONSTITUTION: A mark member 40, wherein the heights are different in the direction of Z in stepwise, is provided on a stage 22. The stage 22 is moved in a plurality of directions, and the positions of marks M1 -Mn provided in the respective steps are measured. Abbe's errors are generated by rolling and pitching. The position reproducibility of the mark 40, which is provided at the height in agreement with the height of a laser beam B reaches the smallest value. As a result, the deviation amount of the present laser beam B from the surface height of a drawing material 10 can be found. Therefore, the Abbe's error can be made extremely small by adjusting the height of the laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adjusting method and a drawing method for drawing with high accuracy in a charged particle beam drawing apparatus which projects an electron beam or an ion beam onto a material to be drawn.

[0002]

2. Description of the Related Art When drawing a pattern in an electron beam drawing apparatus, the range (field) in which the electron beam can be deflected and drawn at one time is limited. A desired drawing of the entire chip is performed in combination with the movement of the stage. At this time, a measurement system using a laser interferometer is prepared to measure the movement amount and position of the stage.

[0003]

When the stage is moved, the irradiation position error of the electron beam occurs due to the rotation after the movement of the stage. The rotation of the stage occurs in three directions: yawing, pitching, and rolling. This electron beam irradiation position error is well known as an Abbe error, and it is desired that the electron beam drawing apparatus draws in three directions of X, Y, and Z under Abbe conditions in which no Abbe error occurs.

The Abbe condition in the Z direction corresponds to making the laser beam by the laser length meter coincide with the height of the drawing material. Conventionally, there has been no method for easily confirming the Abbe condition and adjusting the Abbe error when it occurs. Normally, it is necessary to adjust the stage mechanically while the vacuum of the material drawing chamber in which the stage is placed is broken, but such adjustment in the state where the vacuum is broken requires a great deal of time. Need. In addition, it is necessary to remove the electron optical column from the stage for the adjustment. Therefore, even if the electron optical column is again attached to the stage even if the adjustment is performed, the electron beam optical axis and the material can be accurately adjusted. Therefore, the irradiation position of the electron beam is displaced again as a result.

FIG. 1 shows the Abbe error in the Z direction.
Will be described with reference to. In the figure, S is a stage (including the material to be drawn), the side surface of which is a reflection surface R of the laser beam B. The upper surface of this stage S is the drawing surface D,
The drawing surface D is irradiated with the electron beam EB. The stage S is movable in the horizontal direction (XY direction) by a drive system (not shown). In the figure, the direction perpendicular to the paper surface is the XY direction, and the vertical direction is the Z direction.

As the stage S moves, rolling (horizontal wobbling with respect to the stage moving direction) and pitching (back and forth wobbling with respect to the stage moving direction) occur, and the state S is rotated from the ideal state S. It becomes ´. The center of this rotation is O, and the angle of rotation is θ. It should be noted that at the point O, the point (height of the drawing material) irradiated by the laser beam B and the electron beam coincides, and the Abbe condition is satisfied.

By this rotation, the point A (0, a), which is the irradiation point of the electron beam EB, moves to the point A '(Δx, Δz). The measurement error due to the laser beam B caused by the rotation of the stage S is δL. As a result, the Abbe error Δx due to rolling and pitching is Δx
= A · sin θ. Normally, δL is so small as to be negligible and does not pose a problem, but the Abbe error greatly depends on the amount of stage rotation and the amount of deviation from the laser beam and cannot be ignored.

[0008] Next, FIG.
Will be described with reference to. In the figure, S is a stage as viewed from above. The laser beam B is emitted from both X and Y, and the electron beam is emitted in the direction perpendicular to the drawing. As the stage S moves, yawing occurs and X
It rotates in the Y direction (horizontal direction) and enters the S'state. The center of this rotation is O, and the angle of rotation is θ. By this rotation, the point B (b, 0), which is the irradiation point of the electron beam, becomes B
′ Move to point (b + Δx, Δy). In addition, stage S
Measurement errors due to the laser beam B caused by the rotation of are δLx and δLy. As a result, the Abbe errors Δx and Δy due to yawing are as follows.

[Delta] x = -b (1-cos [theta]) [Delta] y = -b.sin [theta] Even if drawing is performed in the presence of the Abbe error described above, accurate and accurate drawing cannot be performed.

The present invention has been made in view of the above circumstances, and an object thereof is to perform an adjustment method and an accurate drawing in which the Abbe conditions in a charged particle beam drawing apparatus can be easily confirmed and adjusted. To realize the drawing method.

[0011]

According to a first aspect of the present invention, there is provided an adjusting method in a charged particle beam drawing apparatus, wherein a stage on which a material to be drawn is placed is moved, and a desired particle is drawn on the material to be drawn by the charged particle beam. In a charged particle beam drawing apparatus that is configured to monitor the movement amount of the stage with a laser interferometer, a plurality of marks having different heights are arranged on the stage, and the position of each mark is detected by the stage. After moving, it is carried out sequentially, and the height of the mark with the smallest reproducibility of the mark position is obtained through the detection of multiple mark positions, and the height of irradiation of the laser interferometer laser beam to the stage is determined according to this height. The feature is that it is adjusted.

According to a second aspect of the present invention, there is provided an adjusting method in a charged particle beam drawing apparatus, wherein a stage on which a material to be drawn is placed is moved to perform desired drawing on the material to be drawn by the charged particle beam. In a charged particle beam drawing apparatus in which the amount of movement of the stage is monitored by a laser interferometer, a mark is placed on the stage, the mark position is detected after the stage is moved, and the mark position detection operation is performed. The offset deflection amount of the particle beam is made different, and the measurement is performed multiple times.
The feature is that the offset deflection amount of the charged particle beam with the smallest mark position reproducibility is obtained, and the horizontal irradiation position of the laser beam of the laser interferometer on the stage is adjusted according to this deflection amount. There is.

A drawing method in a charged particle beam drawing apparatus according to a third aspect of the present invention is that a stage on which a drawing material is placed is moved to perform desired drawing on the drawing material by the charged particle beam. In a charged particle beam drawing apparatus in which the amount of movement of the stage is monitored by a laser interferometer, the stage is moved, the rotation angle θ of the stage after this movement is obtained, and the charged particle beam is moved in one direction on the material by a distance b. In the case of deflecting only by -b (1-co
sθ), and the deflection position is corrected by −b · sin θ in the other direction.

[0014]

According to the first aspect of the present invention, the positions of a plurality of marks having different heights on the stage are sequentially detected after the stage is moved. The height of the small mark is obtained, and the irradiation height of the laser beam of the laser interferometer to the stage is adjusted according to this height.

According to the second aspect of the present invention, the position of the mark on the stage is detected after the stage is moved, and the mark position detecting operation is performed a plurality of times with different offset deflection amounts of the charged particle beam, and a plurality of marks are detected. Through position detection,
The offset deflection amount of the charged particle beam having the smallest reproducibility value of the mark position is obtained, and the horizontal irradiation position of the laser beam of the laser interferometer on the stage is adjusted according to this deflection amount.

According to the third aspect of the present invention, when the rotation angle θ of the stage after the movement of the stage is obtained and the charged particle beam is deflected on the material by the distance b in one direction, -b (1-
cos θ), and the deflection position is corrected in the other direction by −b · sin θ.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 3 shows an example of a variable area electron beam drawing apparatus for carrying out the method of the present invention. Reference numeral 1 denotes an electron gun that generates an electron beam EB. The electron beam EB generated from the electron gun 1 passes through an illumination lens 2 to a first
It is irradiated onto the shaping aperture 3. The aperture image of the first shaping aperture is imaged on the second shaping aperture 6 by the shaping lens 4, and the position of the image is the shaping deflector 5.
Can be changed by. The image formed by the second forming aperture 6 is projected onto the drawing material 10 via the reduction lens 7 and the objective lens 8. The irradiation position on the drawing material 10 can be changed by the positioning deflector 9.

Reference numeral 11 is a computer, and the computer 11 transfers the pattern data from the pattern data memory 12 to the data transfer circuit 13. Data transfer circuit 1
The pattern data from 3 is supplied to the shot divider 14 and divided into shots. A signal corresponding to the drawing data from the shot divider 14 is supplied to the deflection amplifier 16 for supplying a deflection voltage to the shaping deflector 5 via the DA converter 15 and DA.
The electron gun 1 via the deflection amplifier 18 for supplying the deflection voltage to the positioning deflector 9 via the converter 17 and the DA converter 19
Is supplied to a blanking control circuit 21 which controls a blanking electrode 20 for blanking the electron beam generated from the.

The computer 11 controls the drive mechanism 23 of the stage 22 on which the material 10 is placed in order to move the material in each field. The moving amount of the stage 22 is measured by the laser length measuring device 24, and the measurement result is supplied to the computer 11. Secondary electrons and backscattered electrons are generated by the irradiation of the material 10 with the electron beam EB. For example, the backscattered electrons are detected by a pair of backscattered electron detectors 25. The detection signals of the backscattered electron detector 25 are added by the adder 26, and then the mark signal processing device 2
7 is supplied. A mark scanning signal generation circuit 28 is controlled by the computer 11, and the mark scanning signal generated from this circuit is supplied to the deflection amplifier 18 which supplies the deflection voltage to the positioning deflector 9 via the DA converter 17. . The operation of such a configuration will be described below.

First, a normal drawing operation will be described.
The pattern data stored in the pattern data memory 12 is sequentially read and supplied to the shot divider 14 via the data transfer circuit 13. Based on the data divided by the shot divider 14, the electron beam shaping data is DA
The signal is supplied to the deflection amplifier 16 via the converter 15, and the signal amplified by the amplifier 16 is supplied to the shaping deflector 5. Further, the deflection signal of the electron beam according to the drawing pattern is supplied to the deflection amplifier 18 via the DA converter 17, and the signal amplified by the amplifier 18 is supplied to the positioning deflector 9.

As a result, based on each of the divided pattern data, the shaping deflector 5 shapes the cross section of the electron beam into a rectangular shape having a desired area, and the beam having the rectangular cross section is supplied to the positioning deflector 9. Shots are sequentially shot on the material in accordance with the deflection signal, and a pattern having a desired shape is drawn. At this time, the blanking signal from the blanking control circuit 21 to the blanking electrode 20 causes the blanking of the electron beam in synchronization with the shot of the electron beam on the material 10.

The drawing operation by deflection of the electron beam is performed in field units. After the drawing in a specific field is completed, the stage 22 is moved by the drive mechanism 23 by the length of the field, and The field is drawn. The moving amount of the stage 22 is measured by the laser length measuring device 24, and the measured value is supplied to the computer 11. The computer 11 controls the drive mechanism 23 based on the measured movement amount to enable the accurate movement of the stage 22.

Next, the stage adjusting operation performed prior to the above-described drawing operation will be described. FIG. 4 shows the configuration of the stage portion and the laser length measuring system. The stage 22 is arranged in a work chamber 30 whose interior is evacuated to vacuum. The laser beam B generated by the laser head 31 is split by the beam splitter 32 into two beams for X and Y axis measurement. One of the split beams is bent by a beam bender 33 for X-axis measurement so as to be perpendicular to a stage mirror 34 provided on the side surface of the stage 22. The other split beam is used by the beam bender 35 for Y-axis measurement.
This bends the direction so that it is perpendicular to the stage mirror 34.

Each beam bender 33, 35 is equipped with a mechanism capable of finely adjusting the horizontal and vertical directions of the beam, and as a result, the stage mirror 34 for the laser beam B is attached.
The position of incidence on is adjustable. It should be noted that the laser beam B is used to improve the resolution of the length measurement.
It is configured to make two reciprocations between 6, 37 and the stage mirror 34. The beams that have passed through the interferometers 36 and 37 are incident on receivers 38 and 39, and the receivers 38 and 39 convert the frequency change of light into an electric signal.

On the stage 22, as shown in detail in FIG. 5, mark members 40 having different heights in the Z direction are arranged stepwise. In FIG. 5, (a) shows the mark member 40.
View from the height direction (electron beam irradiation direction), (b)
FIG. 4 is a sectional view of the mark member 40. This mark member 40
Cross marks M1 to Mn are formed on the respective stairs.

First, the detection and correction of the Abbe error due to the pitching and rolling of the stage 22 will be described. The stage 22 is moved from a plurality of directions to measure the positions of the marks M1 to Mn provided on each step on the stairs. For the measurement of the mark position, the stage 22 is moved each time, the moving amount (position) of the stage 22 is measured by the laser measuring system 24, and the mark is arranged below the optical axis of the electron beam. Then, the position of the mark below the optical axis is detected.

The mark position detecting operation at this time will be described. In this case, the electron beam is deflected by the positioning deflector 9 to the cross mark portion, and the electron beam is further scanned at that portion to detect the mark position. As is well known, the mark position is detected by repeatedly scanning the electron beam at the mark portion and detecting backscattered electrons generated as a result. The backscattered electrons are detected by the detector 25, and the detection signals thereof are added by the adder 26 and supplied to the mark signal processing circuit 27. The mark signal processing circuit 27 appropriately differentiates the detection signal to obtain a mark position signal. The mark position signal is supplied to the computer 11 and the mark position is detected.

As described above, the mark position is detected for each of the marks M1 to Mn. However, due to the pitching and rolling of the stage 22, an Abbe error occurs, and the reproducibility of mark position detection is high between the laser beam and each mark. The value depends on the difference in size. That is, the position reproducibility of the mark provided at the height corresponding to the height of the laser beam B becomes the smallest value. As a result, since the amount of deviation of the current laser beam B from the drawing material surface height can be known, the Abbe error can be made extremely small by adjusting the laser beam height by the beam benders 33 and 35. .

Next, the adjustment operation of the Abbe error generated by the yawing of the stage 22 shown in FIG. 2 will be described. In FIG. 2, point O is a point when the position of the laser beam and the position of the electron beam coincide with each other in the X and Y directions.
This is the case when the position is shifted by b. As described above, when the point B is irradiated with an electron beam, an Abbe error occurs and the drawing accuracy deteriorates.

In the present invention, among the marks formed on the mark member 40 on the stage 22, the mark Mm having the same height as the drawing material is used to move the stage 22 from different directions to detect the mark position. In order to adjust the Y-axis laser beam, the mark position reproducibility in the Y direction is examined with the electron beam being deflected in the X direction when the mark is detected (the electron beam irradiation position is shifted). In addition,
The deflection of the electron beam does not mean scanning of the electron beam when performing mark detection, but means giving a constant offset to the electron beam.

The mark position is detected, and the deflection position with the best reproducibility is the irradiation position of the laser beam in the Y direction at present. Therefore, the laser beam may be adjusted by the beam bender 35 by this amount. Alternatively, instead of adjusting the laser beam position, a constant offset may be given to the electron beam. It should be noted that when adjusting the X axis, the same operation as described above is performed.
In that case, it is necessary to deflect the electron beam in the Y direction.

Next, a description will be given of a method for performing accurate drawing in a state where the Abbe condition is broken and an Abbe error has occurred. Consider a state in which the stage 22 rotates clockwise by θ after the movement, as indicated by S and S ′ in FIG. As a result, the measurement errors δLx and δLy occur at the mirror position irradiated with the laser beam, as described above. This error amount can be corrected by feeding back the electron beam deflection regardless of the electron beam deflection position. When the electron beam is not deflected (point O in FIG. 2),
Since the laser beam axis and the electron beam axis match,
Although Abbe error does not occur, deflecting the electron beam causes Abbe error. Therefore, the differences Δx and Δy between the point B and the point B ′ are as follows.

Δx = −b (1−cos θ) Δy = −b · sin θ As a result, if the irradiation position of the electron beam is corrected by the difference Δx, Δy, it is possible to perform highly accurate drawing without error. The above-mentioned rotation angle θ is the same as that of Japanese Patent Laid-Open No. 1-28.
As shown in No. 6420, two interferometers are used for each of the X and Y directions, and two laser beams are applied to each of the interferometers, and it can be calculated from the amount of movement of the stage measured by the two interferometers. The correction amounts Δx and Δy are
This correction amount Δx calculated by the computer 11
Δy is added to the deflection signal supplied from the data transfer circuit 13 to the positioning deflector 9 via the DA converter 17,
The deflection position of the electron beam eliminates the influence of Abbe error.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, although the variable area type electron beam writing apparatus has been described as an example, the present invention can be applied to an ion beam writing apparatus. Further, although the backscattered electrons are detected, it is also possible to detect, for example, secondary electrons generated by irradiation of an electron beam in addition to the backscattered electrons. Furthermore, the variable area type drawing device has been described as an example.
The present invention can also be applied to an apparatus that performs drawing using a spot beam.

[0035]

As described above, according to the invention of claim 1, the positions of a plurality of marks having different heights on the stage are sequentially detected after the stage is moved. Since the height of the mark having a small reproducibility of the mark position is obtained and the irradiation height of the laser beam of the laser interferometer to the stage is adjusted according to this height, the height direction of the stage (Z Abbe error in (direction) can be made extremely small.

According to the second aspect of the present invention, the position of the mark on the stage is detected after the stage is moved, and this mark position detecting operation is performed a plurality of times with different offset deflection amounts of the charged particle beam to obtain a plurality of marks. Through position detection,
Since the offset deflection amount of the charged particle beam with the smallest mark position reproducibility value is obtained and the horizontal irradiation position of the laser beam of the laser interferometer to the stage is adjusted according to this deflection amount, the stage The Abbe error in the horizontal direction (X and Y directions) can be made extremely small.

According to the third aspect of the present invention, when the rotation angle θ of the stage after the movement of the stage is obtained and the charged particle beam is deflected on the material by the distance b in one direction, -b (1-
cos θ), the deflection position is corrected in the other direction by −b · sin θ, so the effect of Abbe error is eliminated,
Highly accurate drawing can be performed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining occurrence of an Abbe error in a height direction after moving a stage.

FIG. 2 is a diagram for explaining the occurrence of an Abbe error in the horizontal direction after moving the stage.

FIG. 3 is a diagram showing an example of an electron beam writing system for carrying out the present invention. .

FIG. 4 is a diagram showing details of a laser interferometer portion.

FIG. 5 is a diagram showing a mark member used in an embodiment of the present invention.

[Explanation of symbols]

 1 electron gun 2 illumination lens 3,6 shaping aperture 4 shaping lens 5,9 deflector 7 reduction lens 8 objective lens 10 material 11 computer 12 memory 13 data transfer circuit 14 shot divider 15, 17, 19 DA converter 16, 18, Deflection amplifier 20 Blanking electrode 21 Blanking control circuit 22 Stage 23 Driving mechanism 24 Laser length measuring device 25 Reflection electron detector 26 Adder 27 Mark signal processing circuit 28 Mark scanning signal generator

Claims (3)

[Claims] 1. A charged particle in which a stage on which a material to be drawn is placed is moved so that desired drawing is performed on the material to be drawn by a charged particle beam, and the amount of movement of the stage is monitored by a laser interferometer. In the beam writing system, multiple marks with different heights are placed on the stage, and the position of each mark is detected sequentially after moving the stage. Is a method for adjusting the height of a small mark, and adjusting the irradiation height of the laser beam of the laser interferometer onto the stage according to this height. 2. A charged particle in which a stage on which a material to be drawn is placed is moved so that desired drawing can be performed on the material to be drawn by a charged particle beam and the amount of movement of the stage is monitored by a laser interferometer. In a beam drawing apparatus, a mark is arranged on a stage, the position of the mark is detected after the stage is moved, and this mark position detection operation is performed a plurality of times with different offset deflection amounts of the charged particle beam. Through the mark position detection, the offset deflection amount of the charged particle beam having the smallest mark position reproducibility value is obtained, and the horizontal irradiation position of the laser beam of the laser interferometer to the stage is adjusted according to this deflection amount. Method for a charged particle beam drawing apparatus which has been used. 3. A charged particle in which a stage on which a material to be drawn is placed is moved so that desired drawing can be performed on the material to be drawn by a charged particle beam and the amount of movement of the stage is monitored by a laser interferometer. In the beam drawing apparatus, the stage is moved, the rotation angle θ of the stage after the movement is obtained, and when the charged particle beam is deflected on the material by the distance b in one direction, −b (1-cos θ) in one direction,
A drawing method in a charged particle beam drawing apparatus in which the deflection position is corrected by -b · sin θ in the other direction.