A method for stabilizing and adjusting a light beam based on a fast mirror

Abstract

A kind of light beam stability adjustment method based on fast reflector, comprising the steps of: S100: according to feedforward adjustment instruction, obtain current light beam position and angle, calculate the deviation between it and target light beam position, angle;S200: determine whether the deviation is within the stroke range of secondary PZT drive, if yes, start secondary PZT drive adjustment, if no, start primary motor drive adjustment;S300: according to feedback adjustment instruction, obtain current light beam position and angle, calculate the deviation between it and target light beam position, angle;S400: determine whether the deviation is within the stroke range of secondary PZT drive, if yes, start secondary PZT drive adjustment, if no, start primary motor drive adjustment;S500: obtain current light beam position and angle, calculate the deviation between it and target light beam position, angle;S600: determine whether the deviation is within the target deviation range, if no, execute step S400, if yes, light beam stability adjustment ends. Through secondary PZT drive and primary motor drive, light beam stability is adjusted quickly and accurately.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithography machine illumination system, and particularly relates to a light beam stability adjustment method based on a fast mirror. BACKGROUND

[0002] In the lithography machine illumination system, the light beam emitted by the laser passes through beam expansion, beam transmission, beam shaping, and uniformity correction, and finally irradiates on a mask plate. In the lithography machine illumination system, the position and angle of the light beam may be offset, thereby causing exposure failure. Therefore, it is necessary to maintain the stability of the light beam in the lithography machine illumination system, and it is a key technology. SUMMARY

[0003] To solve the problem of light beam stability in the lithography machine illumination system, the present application provides a light beam stability adjustment method based on a fast mirror. The two-stage driving of the fast mirror is used to accurately adjust the position and angle of the light beam, so as to achieve the effect of accurate adjustment of the light beam stability.

[0004] The technical scheme provided by the present application is as follows:

[0005] The present application provides a light beam stability adjustment method based on a fast mirror. The fast mirror comprises a first motor drive and a second PZT drive. The light beam stability adjustment method comprises the following steps:

[0006] S100: obtaining the current light beam position and angle according to the feedforward adjustment instruction, and calculating the deviation between the current light beam position and angle and the target light beam position and angle;

[0007] S200: determining whether the deviation is within the stroke range of the second PZT drive. If yes, the second PZT drive is started to adjust. If no, the first motor drive is started to adjust;

[0008] S300: obtaining the current light beam position and angle according to the feedback adjustment instruction, and calculating the deviation between the current light beam position and angle and the target light beam position and angle;

[0009] S400: determining whether the deviation is within the stroke range of the second PZT drive. If yes, the second PZT drive is started to adjust. If no, the first motor drive is started to adjust;

[0010] S500: obtaining the current light beam position and angle, and calculating the deviation between the current light beam position and angle and the target light beam position and angle;

[0011] S600: determining whether the deviation is within the target deviation range. If no, step S400 is executed. If yes, the light beam stability adjustment is ended.

[0012] Further preferably, the fast mirror comprises a position fast mirror for adjusting the position of the light beam and an angle fast mirror for adjusting the angle of the light beam; the position fast mirror and the angle fast mirror comprise the primary motor drive and the secondary PZT drive respectively.

[0013] Further preferably, the secondary PZT drive of the position fast mirror comprises an X-axis position PZT drive and a Y-axis position PZT drive, and the secondary PZT drive of the angle fast mirror comprises an X-axis angle PZT drive and a Y-axis angle PZT drive; the secondary PZT drive is started to adjust, specifically, the X-axis position PZT drive, the Y-axis position PZT drive, the X-axis angle PZT drive and the Y-axis angle PZT drive are controlled respectively, and the position and the angle of the light beam are adjusted according to the displacement changes generated by the PZT drives of the axes.

[0014] Further preferably, the displacement changes generated by the PZT drives of the axes are calculated with the preset transfer matrix to obtain the change amounts of the position and the angle of the light beam.

[0015] Further preferably, the method further comprises a step of calibrating the preset transfer matrix.

[0016] Further preferably, the preset transfer matrix is a transfer matrix in which the X-axis direction and the Y-axis direction are coupled.

[0017] Further preferably, the preset transfer matrix is a transfer matrix in which the X-axis direction and the Y-axis direction are not coupled.

[0018] Further preferably, the current position and angle of the light beam are obtained according to the feedforward adjustment instruction, specifically, the laser is controlled not to emit laser, the fast mirror is adjusted to a predetermined position according to the historical data of the position and the angle of the light beam, and the current position and angle of the light beam at the predetermined position are obtained.

[0019] Further preferably, the current position and angle of the light beam are obtained according to the feedback adjustment instruction, specifically, the laser is controlled to emit laser, and the current position and angle of the light beam are obtained according to the real-time position and angle of the light beam.

[0020] Further preferably, before the step S100, the method further comprises a step of searching zero position by the primary motor drive and a step of restoring the secondary PZT drive to the initial position.

[0021] By the light beam stable adjustment method provided by the application, the position and the angle of the light beam are adjusted for the first time by the secondary PZT drive or the primary motor drive according to the feedforward adjustment instruction, and the position and the angle of the light beam are adjusted for the second time by the secondary PZT drive or the primary motor drive according to the feedback adjustment instruction, so that the effect of stable transmission of the light beam in the illumination system of the lithography machine is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A light beam stability adjustment method flow chart is shown in FIG. 1.

[0023] Figure 2 A transfer matrix calibration flow chart is shown in FIG. 2. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the specific embodiments of the present application will be described below with reference to the drawings. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings, and other embodiments can also be obtained.

[0025] In the actual working state of the fast steering mirror, the structure of the fast steering mirror adopts two-stage transmission. The first-stage transmission mainly realizes large-stroke rotation with certain precision and time response characteristics. One corner of the square platform is supported by a stop bolt, and the adjacent two corners are supported by orthogonal distributed motors. Large-stroke rotation is realized by the extension and retraction of the motor shaft. The second-stage transmission mainly realizes high precision and high response time characteristics of the fast steering mirror. The structure is supported by two-point driving of a piezoelectric ceramic motor (PZT), and the rotation center is supported by a ball hinge. Two degrees of freedom rotation around the steel ball hinge is realized by the extension and retraction of the PZT.

[0026] That is, the first-stage motor drive of the fast steering mirror is driven by two stepping motors. Since the stroke of the motor is large, large-stroke rotation of the fast steering mirror can be realized. The second-stage PZT drive of the fast steering mirror is mainly driven by two PZTs. The PZT has the characteristics of fast response and high precision, and can realize high-precision and fast small-angle rotation of the fast steering mirror.

[0027] The present application applies the fast steering mirror to the illumination system of the lithography machine to adjust the light beam stability of the illumination system of the lithography machine. Based on this, the present application provides a light beam stability adjustment method based on the fast steering mirror. The fast steering mirror adopts two-stage driving, specifically first-stage motor driving and second-stage PZT driving. The present application realizes accurate adjustment of the position and angle of the light beam based on the two-stage driving of the fast steering mirror, so as to achieve the effect of light beam stability. The specific light beam stability adjustment method flow chart is shown in FIG. 1, and specifically includes the following steps. Figure 1

[0028] S100: According to the feedforward adjustment instruction, the current light beam position and angle are obtained, and the deviation between the current light beam position and angle and the target light beam position and angle is calculated.

[0029] ​S200: Determine whether the deviation is within the stroke range of the secondary PZT drive. If yes, start the secondary PZT drive for adjustment; otherwise, start the primary motor drive for adjustment.

[0030] S300: Based on the feedback adjustment command, obtain the current beam position and angle, and calculate the deviation between the current beam position and angle and the target beam position and angle.

[0031] S400: Determine whether the deviation is within the stroke range of the secondary PZT drive. If yes, start the secondary PZT drive for adjustment; otherwise, start the primary motor drive for adjustment.

[0032] S500: Obtain the current beam position and angle, and calculate the deviation between the current beam position and angle and the target beam position and angle.

[0033] S600: Determine whether the deviation is within the target deviation range. If not, proceed to step S400. If yes, the beam stabilization adjustment ends.

[0034] Before step S100, the process includes a first-stage motor drive to find the zero position and a second-stage PZT drive to restore to the initial position. The first-stage motor drive to find the zero position refers to the task of the fast reflector finding a reference position after power-on. The rising edge of the Hall sensor is selected as the reference signal for the fast reflector. Therefore, the first-stage motor drive to find the zero position is as follows:

[0035] 1) After the fast reflector is powered on, the main control board of the fast reflector checks the signal of the Hall sensor.

[0036] 2) If the Hall sensor signal is high, the stepper motor is controlled to move in the negative direction until the Hall sensor signal becomes low. At this time, the stepper linear motor speed is set to low speed, and the stepper motor is controlled to move in the positive direction. If the Hall sensor signal is low, it will continue until the Hall sensor signal becomes high.

[0037] 3) Control the motor to move in the forward direction until the first N-channel signal of the encoder appears.

[0038] 4) Control the motor to move to the calibrated position.

[0039] In this application, the fast reflector includes a position fast reflector for adjusting the position of the beam and an angle fast reflector for adjusting the angle of the beam. The position fast reflector and the angle fast reflector each include a primary motor drive and a secondary PZT drive.

[0040] Specifically, the secondary PZT drive of the position fast reflector includes an X-axis position PZT drive and a Y-axis position PZT drive, and the secondary PZT drive of the angle fast reflector includes an X-axis angle PZT drive and a Y-axis angle PZT drive. The step of starting the secondary PZT drive for adjustment specifically involves controlling the X-axis position PZT drive, the Y-axis position PZT drive, the X-axis angle PZT drive, and the Y-axis angle PZT drive respectively, and adjusting the beam position and angle according to the displacement changes generated by each axis PZT drive.

[0041] For example, a control board with four-axis drive can be used to control the above-mentioned X-axis position PZT drive, Y-axis position PZT drive, X-axis angle PZT drive and Y-axis angle PZT drive. In this application, the changes in beam position and angle are obtained by calculating the transfer matrix. For example, the changes in beam position and angle are obtained by calculating the displacement changes generated by each axis PZT drive with the preset transfer matrix.

[0042] Furthermore, it also includes a step of calibrating a preset transfer matrix. In one embodiment, the preset transfer matrix is ​​a transfer matrix in which the X-axis and Y-axis directions are coupled. In another embodiment, the preset transfer matrix is ​​a transfer matrix in which the X-axis and Y-axis directions are not coupled.

[0043] The preset transfer matrix is ​​a transfer matrix where the X-axis and Y-axis directions are coupled. The specific calculation method is as follows:

[0044]

[0045] Wherein, ΔMP0 is the displacement of axis 0 (the X-axis of the position control fast reflector);

[0046] ΔMP1 is the displacement of axis 1 (the Y-axis of the position control fast reflector);

[0047] ΔMP3 is the displacement of axis 3 (the X-axis of the angle-controlled fast reflector);

[0048] ΔMP2 is the displacement of axis 2 (the Y-axis of the angle-controlled fast reflector);

[0049] The calibration process for a transfer matrix where coupling exists in the X and Y axes is as follows: Figure 2 As shown;

[0050] This represents the changes in the position and angle of the light beam along the X and Y axes.

[0051] The default transfer matrix is ​​the transfer matrix in which there is no coupling between the X-axis and Y-axis directions. The specific calculation method is as follows:

[0052]

[0053] For the transfer matrix without coupling in the X-axis direction and the Y-axis direction, the calibration process of the transfer matrix is as shown in Figure 2

[0054] In step S100, the current beam position and angle are obtained according to the feedforward adjustment instruction, specifically: the laser is controlled not to emit laser, the fast steering mirror is adjusted to a predetermined position according to the historical data of the beam position and angle, and the current beam position and angle at the predetermined position are obtained.

[0055] In step S300, the current beam position and angle are obtained according to the feedback adjustment instruction, specifically: the laser is controlled to emit laser, and the current beam position and angle are obtained according to the real-time beam position and angle.

[0056] Through the above steps S100-S600, the beam stable adjustment method provided by the application first adjusts the beam position and angle by the secondary PZT drive or the primary motor drive according to the feedforward adjustment instruction, and then adjusts the beam position and angle by the secondary PZT drive or the primary motor drive according to the feedback adjustment instruction, so as to achieve the effect of stable transmission of the beam in the lithography machine illumination system.

[0057] The above application of specific examples to the present application is described, which is only used to help understand the present application, and does not limit the present application. For the skilled in the art to which the present application belongs, according to the idea of the present application, several simple deductions, deformations or substitutions can be made.​

Claims

1. A beam stabilization adjustment method based on a fast-reflecting mirror, characterized in that, The fast reflector includes a primary motor drive and a secondary PZT drive, and the beam stabilization adjustment method includes the following steps: S100: Obtain the current beam position and angle according to the feedforward adjustment command, and calculate the first deviation between the current beam position and angle and the target beam position and angle; S200: Determine whether the first deviation is within the stroke range of the secondary PZT drive. If yes, start the secondary PZT drive for adjustment; otherwise, start the primary motor drive for adjustment. S300: Based on the feedback adjustment command, obtain the current beam position and angle, and calculate the second deviation between the current beam position and angle and the target beam position and angle; S400: Determine whether the second deviation is within the stroke range of the secondary PZT drive. If yes, start the secondary PZT drive for adjustment; otherwise, start the primary motor drive for adjustment. S500: Obtain the current beam position and angle, and calculate the third deviation between the current beam position and angle and the target beam position and angle; S600: Determine whether the third deviation is within the target deviation range. If not, execute step S400. If yes, the beam stabilization adjustment ends. The adjustment of the secondary PZT drive is achieved through a preset transfer matrix, which maps the displacement changes of each axis PZT drive to the changes in beam position and angle, and the transfer matrix is ​​calibrated.

2. The beam stabilization adjustment method as described in claim 1, characterized in that, The fast reflector includes a position fast reflector for adjusting the position of the beam and an angle fast reflector for adjusting the angle of the beam; the position fast reflector and the angle fast reflector respectively include a primary motor drive and a secondary PZT drive.

3. The beam stabilization adjustment method as described in claim 2, characterized in that, The secondary PZT drive of the position fast reflector includes an X-axis position PZT drive and a Y-axis position PZT drive, and the secondary PZT drive of the angle fast reflector includes an X-axis angle PZT drive and a Y-axis angle PZT drive. The activation of the secondary PZT drive for adjustment specifically involves controlling the X-axis position PZT drive, the Y-axis position PZT drive, the X-axis angle PZT drive, and the Y-axis angle PZT drive respectively, and adjusting the beam position and angle according to the displacement changes generated by each axis PZT drive.

4. The beam stabilization adjustment method as described in claim 1, characterized in that, It also includes the step of calibrating the preset transfer matrix.

5. The beam stabilization adjustment method as described in claim 1, characterized in that, The preset transfer matrix is ​​a transfer matrix in which the X-axis and Y-axis directions are coupled.

6. The beam stabilization adjustment method as described in claim 1, characterized in that, The preset transfer matrix is ​​a transfer matrix in which there is no coupling between the X-axis and Y-axis directions.

7. The beam stabilization adjustment method as described in claim 1, characterized in that, The step of obtaining the current beam position and angle according to the feedforward adjustment command specifically involves: controlling the laser to not emit laser light, adjusting the fast reflector to a predetermined position based on historical data of beam position and angle, and obtaining the current beam position and angle at that predetermined position.

8. The beam stabilization adjustment method as described in claim 1, characterized in that, The step of obtaining the current beam position and angle based on feedback adjustment instructions specifically involves controlling the laser to emit laser light and obtaining the current beam position and angle based on the real-time beam position and angle.

9. The beam stabilization adjustment method as described in claim 1, characterized in that, Before step S100, the process also includes a step of finding the zero position using a primary motor drive and a step of restoring the secondary PZT drive to the initial position.

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