JP2001326170A - Adjustment method in beam processing device - Google Patents

Abstract

(57) [Problem] To provide an adjustment method in a beam processing apparatus capable of preventing occurrence of an error in a beam processing position due to yawing, pitching, and rolling caused by stage movement. The position of the stage in the X direction is measured by three lasers x1, x2, and x3, and the position of the stage in the Y direction is measured by three lasers y1, y2, and y3. X
The rotation amount of the shaft is obtained from the difference between the value based on the laser y3 and the value based on the laser y1. The rotation amount of the Y axis is obtained from the difference between the value based on the laser y3 and the value based on the laser y1. The rotation amount of the Z axis is obtained by averaging the difference between the laser x2 and the laser x1 and the difference between the laser y2 and the laser y1. The movement amount and the rotation amount thus obtained are supplied to the computer 11, and the correction amount of the irradiation position of the electron beam is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam processing apparatus such as a charged particle beam drawing apparatus for projecting an electron beam or an ion beam onto a material to be drawn. The present invention relates to an adjustment method in an apparatus.

[0002]

2. Description of the Related Art When a pattern is drawn in an electron beam drawing apparatus, the range (field) in which the electron beam can be deflected and drawn at a 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, an error occurs in the irradiation position of the electron beam due to the rotation after the movement of the stage. The rotation of the stage occurs in three directions: yawing, pitching, and rolling. This irradiation position error of the electron beam is well known as Abbe error, and it is desired that the electron beam drawing apparatus performs drawing in three directions of X, Y, and Z under Abbe conditions in which Abbe error does not occur.

[0004] The Abbe condition in the Z direction corresponds to making the height of the drawing material coincide with the laser beam obtained by the laser length measuring device. Conventionally, there has been no method for easily confirming the Abbe condition and adjusting the Abbe error when it has occurred. Normally, it is necessary to mechanically adjust the laser beam axis while breaking the vacuum of the material drawing chamber where the stage is placed,
Such adjustment in a state where the vacuum is broken requires a great deal of time. In addition, for adjustment, it is necessary to remove the electron optical column from the stage. Therefore, even if the adjustment is performed, even if the electron optical column is mounted on the stage again, the electron beam optical axis and the material can be accurately detected. Cannot be matched with each other, and the irradiation position of the electron beam is shifted again as a result.

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

The stage S undergoes rolling (swaying in the moving direction of the stage) and pitching (swing back and forth in the moving direction of the stage) as it moves, and the state S rotated from the ideal state S. '. The center of this rotation is O, and the angle of rotation is θ. At the point O, the point irradiated with the laser beam B and the electron beam (the height of the drawing material) coincides, and the Abbe condition is satisfied.

[0007] By this rotation, point A (0, a), which is the irradiation point of the electron beam EB, moves to 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, Abbe error Δx due to rolling and pitching becomes Δx
= A · sin θ. Normally, δL is negligibly small and poses no problem. However, Abbe error greatly depends on the amount of rotation of the stage and the amount of deviation from the laser beam, and is not negligible.

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

Δx = −b (1−cos θ) Δy = −b · sin θ Even if drawing is performed in the presence of Abbe error due to yawing, pitching, and rolling, accurate and accurate drawing cannot be performed.

[0010] The present invention has been made in view of the above points, and has as its object the purpose of yawing accompanying stage movement,
An object of the present invention is to realize an adjustment method in a beam processing apparatus that can prevent an error in a beam processing position due to pitching and rolling.

[0011]

According to a first aspect of the present invention, there is provided an adjustment method in a beam processing apparatus, wherein a stage on which a material to be processed is mounted is moved, and a desired drawing or the like is performed on the material to be processed by a beam. In addition, in a beam processing apparatus in which the amount of movement of the stage is monitored by a laser interferometer, three laser beams are irradiated from the interferometer onto a mirror that moves together with the stage, and the three laser beams are used based on the three laser beams. The amount of rotation of the stage (material) is obtained based on the measured amount of movement of the type, and the relative position between the beam irradiated on the material to be processed and the material to be processed is corrected according to the obtained amount of rotation. It is characterized by an adjustment method in the beam processing apparatus described above.

According to the first aspect of the present invention, three laser beams are irradiated from an interferometer to a mirror moving together with a stage,
Based on three kinds of movement amount measurement values based on three laser beams, at least the X-axis and Y-axis rotation amounts of the stage (material) are obtained, and the beam applied to the material to be processed according to the obtained rotation amounts And the relative position of the material to be processed is corrected.

According to a second aspect of the present invention, the position correction in the first aspect is performed by correcting the irradiation position of the beam projected on the material. The invention of claim 3 of the present invention is characterized in that the position correction in the invention of claim 1 is performed by mechanically moving the material.

[0014]

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 type electron beam writing 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 is irradiated onto a first shaping aperture 3 via an illumination lens 2. The aperture image of the first shaping aperture is formed on the second shaping aperture 6 by the shaping lens 4, and the position of the image can be changed by the shaping deflector 5. The image formed by the second forming aperture 6 is irradiated onto the drawing material 10 via the reduction lens 7 and the objective lens 8. Drawing material 10
The irradiation position of the laser beam can be changed by the positioning deflector 9.

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

The computer 11 controls a driving mechanism 23 of a stage 22 on which the material 10 is placed for moving the material in each field. The movement amount of the stage 22 is measured by the laser length measuring device 24, and the measurement result is supplied to the computer 11. Irradiation of the material 10 with the electron beam EB generates secondary electrons and reflected electrons. For example, the reflected electrons are detected by a pair of reflected electron detectors 25. After the detection signal of the backscattered electron detector 25 is added by the adder 26, the mark signal processing device 2
7 is supplied. Reference numeral 28 denotes a deflector control circuit, which includes a shift register. The deflector control circuit 28 is controlled by the computer 11, and a signal generated from this circuit is supplied via a DA converter 17 to a deflection amplifier 18 which supplies a deflection voltage to the positioning deflector 9. The operation of such a configuration will now be described.

First, a normal drawing operation will be described.
The pattern data stored in the pattern data memory 12 is sequentially read out and supplied to the shot divider 14 via the data transfer circuit 13. Based on the data divided by the shot divider 14, the shaping data of the electron beam 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. The deflection signal of the electron beam according to the drawing pattern is supplied to the deflection amplifier 18 via the deflector control circuit 28 and the DA converter 17, and the signal amplified by the amplifier 18 is supplied to the positioning deflector 9. You.

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

The drawing operation by the deflection of the electron beam is performed in units of fields. After drawing in a specific field is completed, the stage 22 is moved by the length of the field by the driving mechanism 23, and the next operation is performed. The field is drawn. The amount of movement 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, and enables the accurate movement of the stage 22.

Next, the stage adjustment 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 disposed in a work chamber whose inside is evacuated to a vacuum. The laser beam B generated from the laser head 31 is split by the beam splitter 32 into two beams for measuring the X and Y axes. The direction of one of the split beams is bent by a beam bender 33 for X-axis measurement so that the beam is perpendicular to a stage mirror 34x provided on the side surface of the stage 22. The direction of the other split beam is bent by a beam bender 35 for Y-axis measurement so that the beam is perpendicular to the stage mirror 34y.

Each of the beam benders 33 and 35 is provided with a mechanism capable of finely adjusting the horizontal and vertical directions of the beam. As a result, the stage mirror 34 of the laser beam B is provided.
Is adjustable. The laser beam B is divided into three laser beams by the interferometers 36 and 37, respectively, and the amount of movement of the stage 22 based on each of the laser beams is measured.

That is, three beams x1, x2, and x3 are irradiated on the mirror 34x as laser beams for X-axis measurement. An interferometer 36 is provided for each of these three laser beams.
Then, the light interferes with the reference light, and each interference light is detected. Also, as a laser beam for Y-axis measurement, y1, y
The three beams 2 and y3 are irradiated on the mirror 34y.
The interferometer 37 causes the interference light to interfere with the reference light for each of the three laser beams, and each interference light is detected. A total of six types of signals detected by the respective interferometers 36 and 37 are supplied to the computer 11.

As described above, the position of the stage in the X direction is measured by three lasers x1, x2, and x3, and the position is an average of three types of position information based on the three beams. Desired. Similarly, the position of the stage in the Y direction is measured by three lasers y1, y2, and y3.
As the position, an average of three types of position information based on three beams is obtained.

The amount of rotation on the X axis is obtained from the difference between the value based on the laser y3 and the value based on the laser y1. The amount of rotation of the Y axis is obtained from the difference between the value based on the laser x3 and the value based on the laser x1. The rotation amount of the Z axis is obtained by averaging the difference between the laser x2 and the laser x1 and the difference between the laser y2 and the laser y1. The movement amount and the rotation amount obtained in this way are supplied to the computer 11.
FIG. 5 shows the stage mirror 34 viewed from the + Y axis direction.
The positional relationship between three lasers y1, y2, and y3 irradiated to y is shown.

In the drawing system shown in FIG. 1, at the time of drawing, a step-and-repeat method is used.
The movement of the stage 22 and the drawing by the electron beam for each field are repeated. At this time, the next X axis, Y axis,
The correction operation for the rotation of the Z axis is performed in parallel.

Next, an operation for removing the influence of Abbe error will be described. First, every time the stage stops, the yaw, pitch, and rolling values are read. In this case, pitching and rolling change depending on the moving direction of the stage, and therefore, the rotation is actually X and Y axes. That is, when moving in the X direction, the X axis rotation is rolling, and the Y axis rotation is pitching.

Thereafter, the field rotation is corrected by the same angle as the read yawing amount. This rotation correction
In accordance with a command from the computer 11, the deflector control circuit 2
In step 8, the position of the deflection range of the electron beam is rotated and shifted in accordance with the rotation correction value.

At the same time, the Abbe error value measured in advance is read, and the computer 11 calculates the shift correction value. The calculated shift correction is supplied from the computer 11 to the deflector control circuit 28. The yaw correction value and the shift correction value described above are added and stored in a shift register in the deflector control circuit, and the electron beam irradiation position at the time of drawing is corrected. In this way, at the time of actual drawing by the electron beam, the field rotation correction and the shift correction are performed.

Here, the correction formula will be described. First, the shift correction amount based on the yawing value is Bx,
The position of the electron beam axis as seen from the laser axis intersection,
Is the yawing value, the shift correction amount Syawx in the X direction
And the shift correction amount Syawy in the Y direction can be obtained by the following equation.

Syawx = ｛Bx × cos (θyaw) −By × sin
(Θyaw)｝ − Bx Syawy = {Bx × sin (θyaw) −By × cos (θyaw)} −
By is the shift amount of the electron beam irradiation area due to pitching and rolling. Hx and Hy are Abbe error values, that is, the difference between the laser axis height in the X and Y directions and the material surface height, and θy is the Y axis. Assuming that the rotation angle and θx are rotation angles of the X axis, shift correction values (rotation correction values) Sx and Sy are obtained by the following equations.

Sx = Hx.times.sin (.theta.y) Sy = Hy.times.sin (.theta.x) By the way, when the center of rotation of the yawing is the center of the square formed by the stage mirror, there is no Abbe error, for example, when the laser beam and the electron beam are drawn. In a state where the position coincides with the field center position, only the rotation of the field needs to be corrected, and the shift need not be corrected. Strictly, there is a laser length measurement error due to the mirror being tilted, but this amount can be ignored. That is,
Even if the yawing is 3 seconds or less and the Abbe error is 1 mm, the laser measurement error is less than 1 nm. In this case, even if the rotation center is shifted, it can be ignored.

FIG. 1 shows a state of displacement due to pitching and rolling when there is an Abbe error. When there is no Abbe error, the center of the drawing field does not deviate and no displacement occurs. Also, the amount of change in the field size is so small that it can be ignored. For example, the deviation of the drawing field is obtained by the following equation.

[Field size] × {1−cos [rotation angle｝]} As a result, the field size is 1 mm and the pitch is 10
Even in seconds, the deviation of the drawing field is at most 0.00
1 nm. Further, a laser length measurement error due to the inclination of the mirror occurs, but this error can be ignored.

Next, a method for eliminating the influence of Abbe error will be described. First, during drawing after the stage has stopped, the difference between the stop position of the stage and the current position (hereinafter referred to as
LBC) is always fed back as a correction of the irradiation position of the electron beam by high-speed synchronization.

When calculating the LBC, three lasers x
An average value is calculated by multiplying 1, x2 and x3 by a certain weight. Similarly, calculation is performed for three lasers y1, y2, and y3. This weighting is determined so that even if there is an Abbe error, it is corrected.

FIGS. 6 and 7 are reference diagrams for obtaining a correction value for Abbe error. FIG. 6 is a diagram viewed from the + Z axis, and FIG. 7 is a diagram viewed from the + X axis direction. Stage mirror 34
The target plane of y is T, and the plane shifted from the target plane is T '. The electron beam position P is at the center C1 of the laser beams y1 and y2.
The state is shifted to the left by ax from the left. The material position is shifted az below the center C2 of the laser beams y1 and y3. The measured value by each laser axis is
They are y1, y2, and y3, respectively.

The current position of the stage is shifted as shown in FIGS. 6 and 7, and the horizontal correction value (LBCy) of Abbe error under this condition is obtained by the following equation. LBCy = {(DX / 2) -ax} (y1-y2) / DX The LBC123 of the Y axis to be corrected in consideration of the LBCy at the horizontal electron beam position and the LBC in the height direction is obtained by the following equation. Can be

LBC123 = {(DZ / 2) −az} (LBCy−y3) / DZ The obtained value of LBC123 is supplied from the computer 11 to the deflector control circuit 28. As a result, the sample 10 Irradiation is performed with the electron beam from which the influence of the electron beam is removed.

FIG. 2 shows the state of the displacement when yawing occurs. Here, the center of rotation of the yawing is set to the center of the square formed by the stage mirror. This figure 2
However, when there is no Abbe error, that is, when the laser beam axis coincides with the field center position of the electron beam writing, only the rotation of the field needs to be corrected, and the shift does not need to be corrected. Strictly speaking, a laser length measurement error due to the tilt of the mirror occurs, but this amount can be ignored. For example, if yawing is 3
Even if the second and Abbe error are 1 mm, the laser length measurement error is less than 1 nm. Also, even if the rotation center is shifted,
The effect is negligible.

FIG. 1 shows the state of displacement due to pitching and rolling when there is an Abbe error. However, when there is an Abbe error, the position (center of the drawing field) does not deviate. Also, the amount of change in the field size is so small that it can be ignored. This quantity is determined by the following equation.

[Field size] × {1-cos [rotation angle]} Therefore, the field size is 1 mm, and the pitching 10
In seconds, the amount of change in the field size is as small as 0.001 nm. Furthermore, a laser length measurement error due to the tilt of the mirror occurs, which is also negligibly small.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, although a 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, the reflected electrons are detected. However, other than the reflected electrons, for example, secondary electrons generated by irradiation of an electron beam may be detected. Furthermore, although the variable area type drawing apparatus has been described as an example,
The present invention can be applied to an apparatus that performs writing using a spot beam and an apparatus that irradiates a material with a laser beam.

Further, the correction value is obtained by shifting the electron beam irradiation position or the like, but may be fed back to a mechanical movement loop of the stage. The present invention is not limited to the step-and-repeat method, and can be applied to a stage continuous movement method. And
Although three laser beams were used to measure the movement amounts of the X axis and the Y axis, the positional relationship between the irradiation of the three beams to the mirror is not limited to the positional relationship shown in FIG.

[0044]

As described above, according to the first aspect of the present invention, three laser beams are radiated from the interferometer to the mirror that moves together with the stage, and the three laser beams are emitted based on the three laser beams.
At least the X-axis, Y-axis, and Z-axis rotation amounts of the stage (material) are obtained based on the type of movement amount measurement values, and the beam irradiated onto the material to be processed and the beam The relative position is corrected. As a result, it is possible to prevent an error in the beam processing position due to yawing, pitching, and rolling caused by the stage movement.

In the second aspect of the present invention, the position correction in the first aspect of the invention is performed by correcting the irradiation position of the beam projected on the material. Can be achieved.

According to the third aspect of the present invention, the position correction in the first aspect of the invention is performed by mechanically moving the material, so that the same effect as that of the first aspect can be achieved.

[Brief description of the drawings]

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

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

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

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

FIG. 5 is a diagram showing an irradiation positional relationship of three laser beams irradiated to a stage mirror.

FIG. 6 is a diagram used to derive an equation for obtaining a correction value of Abbe error.

FIG. 7 is a diagram used to derive an equation for obtaining a correction value of Abbe error.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Illumination lens 3,6 Molding aperture 4 Molding 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 Drive mechanism 24 Laser length measuring device 25 Backscattered electron detector 26 Adder 27 Mark signal processing circuit 28 Deflector control circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI theme coat テ ー マ (Reference) H01J 37/20 H01L 21/30 541D F-term (Reference) 2F065 AA03 AA39 BB15 BB25 CC17 DD03 FF55 GG04 LL46 MM03 MM04 PP12 QQ17 QQ23 2H097 AA03 AB05 BA10 BB10 CA16 KA01 KA29 5C001 AA03 AA04 AA06 CC06 5F056 AA04 CB22 CB25 CC05

Claims (3)

[Claims] 1. A beam in which a stage on which a material to be processed is mounted is moved so that desired processing such as drawing is performed on the material to be processed by a beam, and the amount of movement of the stage is monitored by a laser interferometer. In the processing device,
The three laser beams are irradiated from the interferometer onto the mirror that moves together with the stage, and the amount of rotation of the stage (material) is obtained based on three types of measured amounts of movement based on the three laser beams. An adjustment method in a beam processing apparatus configured to correct a relative position between a beam irradiated on a material to be processed and a material to be processed in accordance with the method. 2. The adjustment method according to claim 1, wherein the position correction is performed by correcting an irradiation position of a beam projected on the material. 3. The adjustment method according to claim 1, wherein the position correction is performed by mechanically moving the material.