JP2957265B2 - UV laser processing equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet laser processing apparatus, and in particular, each part in an ultraviolet laser processing apparatus in which a processing optical system and an observation optical system are different and an irradiation position and a shape are affected by a multiaxial element. And a position correction method.

2. Description of the Related Art In general, in a laser processing apparatus, only a defective portion is removed without damaging a normal pattern.
It is necessary to accurately perform laser beam irradiation during processing. For this reason, in the conventional apparatus, the laser light and the probe light have the same optical axis, and the image on the mask surface passing through the slit can be easily observed with a microscope.

For example, as shown in “Photomask Correction Processing Technology”, Electronic Materials (Industry Research Council, page 49, 1978-3: Tatsumi Tatsumi), the observation optical system and the processing optical system may be the same optical system. This is customary in conventional devices.

By the way, in a processing apparatus using an ultraviolet laser, if they are to have the same configuration, a great burden is required in designing an objective lens of each optical system, and it is very difficult to manufacture the objective lens. This is because the wavelength of ultraviolet light is short. Therefore, the observation optical system and the processing optical system need to be different optical systems, and therefore, their position correction and the like are required.

That is, in an ultraviolet laser processing apparatus in which the observation optical system and the processing optical system are different from each other, it is necessary to adjust the observation optical system and the processing optical system so as to match each other in consideration of each operation. The observation optical system has three axes (X, Y, Z), the processing optical system has three axes (X, Y, Z), the stage has two axes (X, Y), and the variable slit has the number of slit plates. Since it is movable in the 2 (X, Y) +1 (θ) axis, there are many possible causes of errors in the laser irradiation position.

In addition, various patterns of the laser irradiation shape can be considered depending on the combination of the slit plates, the amount of movement of each slit plate, and the like.

Therefore, there is a defect that the laser irradiation position and the irradiation shape displayed on the monitor screen by using image processing or the like are different from the actual laser irradiation position and the actual shape.

An object of the present invention is to solve the above-mentioned conventional disadvantages, and an object of the present invention is to accurately display an irradiation shape at an irradiation position even when an observation optical system and a processing optical system are different. An object of the present invention is to provide an ultraviolet laser processing apparatus capable of performing the above processing.

An ultraviolet laser processing apparatus according to the present invention includes a laser emitting unit that emits an ultraviolet laser, and a plurality of slit plates that move to positions according to external commands, respectively. Move the optical laser to a variable slit to deform it into a predetermined shape and a position according to an external command,
The processing optical system for irradiating the workpiece with the ultraviolet light laser after passing through the plurality of variable slits, and moved to a position according to an external command, and observed the irradiation position of the ultraviolet light laser by the processing optical system. An ultraviolet optical laser processing apparatus including an observation optical system to be moved, and a mounting table that moves to a position according to an external command and on which the workpiece is mounted, wherein the plurality of slit plates are arranged with respect to an optical axis center. First position correcting means for correcting the position of each of the slit plates so that each is located at a predetermined position, second position correcting means for correcting the position of the processing optical system after this position correction, and this position correction A third position correcting unit for correcting the position of the observation optical system later, and a fourth position correcting unit for correcting the position of the processing optical system by moving the mounting table after the position correction. I do.

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration diagram of an embodiment of an ultraviolet laser processing apparatus according to the present invention.

In the figure, an ultraviolet laser processing apparatus according to an embodiment of the present invention includes an ultraviolet laser oscillator 7 for emitting an ultraviolet laser, such as an excimer laser, and a plurality of lasers for changing the cross-sectional shape of the emitted laser. A variable slit 6 including a slit plate, a processing optical system 4 for irradiating a workpiece (not shown) on a worktable 5 with a laser, and an observation optical system 3 including an objective lens for observing a state of the processing. And a monitor 1 such as a CRT, and a control unit 2 for controlling each unit.

The moving axes of the slit plates, the processing optical system, the observation optical system, and the mounting table are driven by a known stepping motor. The workpiece is a transparent glass plate, and is placed on a frame-shaped stage. Therefore, the processing state of the workpiece can be observed through the workpiece itself.

In the apparatus according to the present embodiment having the above-described configuration, the work is performed such that the laser irradiation position on the work (not shown) placed on the worktable 5 is located below the observation optical system 3 during processing. The table 5 and the observation optical system 3 are moved. At the same time, the position of the processing optical system 4 is adjusted to that of the observation optical system 3.

Next, the image of the workpiece read from the camera of the observation optical system 3 for display on the screen of the monitor 1 and subjected to the image processing of the control unit 2 and the image of the entire slit plates 8 and 9 by the control unit 2 Based on the position and the slit shape calculated and output from the positional relationship between the observation optical system 3 and the processing optical system 4, the variable slit 6 and the processing optical system 4 are moved to determine the laser irradiation position and the shape, and the processing is performed. Do.

The position correction procedure before the processing will be described with reference to FIG. FIG. 2 is a flowchart showing a procedure for calculating a correction value of the position of each unit. In the figure, a first step of correcting the optical axis, a second step of correcting the slit plate, a third step of correcting the processing optical system and the observation optical system, and a shift of the processing optical system due to the movement of the stage. , A total of four steps of the fourth step of performing the correction are shown. Note that the first step is not necessarily required if the actual optical axis of the laser light is input.

First, in the first step, as shown in FIG. 3A, the upper right corner of the slit plate 8 and the lower left corner of the slit plate 9 are designed with respect to the respective X and Y coordinate systems. A laser beam is irradiated in accordance with the axis, and a correction value of the center coordinate of the optical axis is calculated for each slit plate. (Step 21). In this case, the glass plate is irradiated with laser light, and the irradiation position is read as the actual optical axis center coordinates. The correction value is calculated for each of the X and Y coordinate systems of the slit plate 8 and the slit plate 9 (designed optical axis center 1).
1 (X, Y coordinates) − (X, Y coordinates of the actual optical axis center 12).

FIG. 3 (b) is a schematic view of the slit plate 8 and the slit plate 9, and the light-shielding portions are indicated by hatched portions. That is,
The slit plate 8 is composed of two transmission circular slits and three transmission rectangular slits, and the slit plate 9 is composed of three transmission rectangular slits and two light shielding circular slits. That is, in the rectangular glass plate, both slit plates can be obtained by masking only the hatched portions in FIG. In addition to these slit plates moving in the X and Y axis directions,
The whole rotates and moves.

Next, in the second step, a correction value related to the slit 6 is calculated. First, each slit plate 8, 9 is moved one axis at a time, and a correction value due to the movement is calculated (step 22). FIG. 3 (c) shows a method of calculating a correction value when the slit plate 8 is moved in the X-axis direction. The middle rectangular slit of the slit plate 9 is moved to the corrected optical axis center, and the slit plate 8 is further moved. Is moved so that a small rectangular slit at the lower right of the optical axis comes to the center of the optical axis, and is irradiated with laser light. The irradiation shape is 13, and the center coordinate is the irradiation center 14 (X1, Y1) before the movement.

Next, the large rectangular slit at the lower left of the slit plate 8 moves so as to come to the center of the optical axis (the small rectangular slit at the lower right and the large rectangular slit at the lower left of the slit plate 8 have the same design Y-axis coordinate). Therefore, the movement is performed only in the X-axis direction.), And the irradiation is performed while overlapping the previous irradiation. The shape is the irradiation shape 15 after the movement, and its center coordinate is the irradiation center 16 (X
2, Y2).

Here, the correction value para when the slit plate 8 moves in the X-axis direction
5, para6 is obtained by the following equations (1) and (2).

para5 = {(X1-X2) / objective lens reduction ratio} / X-axis direction movement amount ... (1) para6 = {(Y1-Y2) / objective lens reduction ratio} / X-axis movement amount ... (2) In other words, since the movement is only in the X-axis direction, there should be essentially no shift in the Y-axis direction. However, in practice, the shift occurs, and this is corrected by para6 in equation (2). .

Similarly, a large rectangular slit at the lower left of the slit plate 8 and a small circular slit at the upper left having the same design X-axis coordinate as the rectangular slit are used.
Is moved only in the Y-axis direction. The correction values para7 and para8 due to the movement of the slit 8 only in the Y-axis direction are obtained by the following equations (3) and (4).

para7 = {(X3-X4) / objective lens reduction ratio} / movement amount in Y-axis direction (3) para8 = {(Y3-Y4) / objective lens reduction ratio} / movement amount in Y-axis direction (4) In other words, since the movement is only in the Y-axis direction, there should be essentially no shift in the X-axis direction. However, in practice, the shift occurs, so this is corrected by para7 in equation (3). .

In equations (1) to (4), (X1, Y1) is the irradiation center before moving only in the X-axis direction, (X2, Y2) is the irradiation center after moving only in the X-axis direction, and (X3, Y3). (Y3) is the irradiation center before movement only in the Y-axis direction, and (X4, Y4) is the irradiation center after movement only in the Y-axis direction. X1-X2, Y1-Y2, X3-X4, Y3-Y4
Is calculated as the number of pixels on the monitor.

Similarly, the corrected movement amount (XS8, YS8) of the slit 8 is obtained by the following equations (5) and (6) with respect to the required movement amounts (xs8, ys8) in the X and Y directions.

XS8 = (1 + para5) * xs8 + para7 * ys8 (5) YS8 = (1 + para8) * ys8 + para6 * xs8 (6) Similarly, correction values para9, para10, and the Y-axis direction by moving the slit 9 in the X-axis direction. Correction value para1 due to movement of
1. Find para12 and apply correction. After performing the same processing for all the slit plates, a position correction value between the respective slit plates is calculated based on a certain one of the slit plates (step 23).

FIG. 3 (d) shows a method of calculating the position correction value, in which a large transmission circular slit at the upper right of the slit plate 8 and a small light shielding circular slit at the lower right of the slit plate 9 are aligned with the optical axis center. Move to come to and irradiate.

FIG. 3D shows the irradiation shape, and as shown in FIG. 3, the difference between the two circles is determined by the circular slit irradiation shape 17 of the slit plate 8 and the circular light-shielding slit irradiation shape 18 of the slit plate 9. The part (donut part) is irradiated.

Here, the position correction values para13, para13, are obtained from the center coordinates (X5, Y5) of the circular slit irradiation shape 17 of the slit plate 8 and the center coordinates (X6, Y6) of the circular light shielding slit irradiation shape 18 of the slit plate 9.
para14 is obtained by the following equations (7) and (8).

para13 = (X5−X6) / objective lens reduction ratio... (7) para14 = (Y3−Y4) / objective lens reduction ratio... (8) In this example, the slit plate 9 is In order to perform the correction, the correction movement amount of the slit plate 9 (XS9,
YS9) is obtained by the following equations (9) and (10) for the required movement amounts xs9 and ys9 in the X and Y directions, respectively.

XS9 = (1 + para9) * xs9 + para11 * ys9 + para13 (9) YS9 = (1 + para12) * ys9 + para10 * xs9 + para14 (10) In the third step of correcting the observation optical system 3 and the processing optical system 4, first, the third step is performed. As shown in FIG. 5E, the processing optical system 4 is moved only in the X-axis direction by the X-axis movement amount XA as shown by the arrow A within the range of the monitor screen projected from the observation optical system 3, and moves before and after the movement. Later, it is irradiated with a laser. The irradiation center before the movement in the X-axis direction at this time is (X7, Y7), and the irradiation center after the movement in the X-axis direction is (X8, Y8). Then, the equation (1
1), (12), correction value by movement in X-axis direction para15, pa
Calculate ra16. Similarly, the movement amount YA in the Y-axis direction only in the Y-axis direction.
The laser beam is irradiated before and after the movement.
Then, the irradiation center before moving in the Y-axis direction at this time is set to (X9, Y
9) The irradiation center after the movement in the Y-axis direction is set to (X10, Y10), and the correction value para1 due to the movement in the Y-axis direction is calculated by Expressions (13) and (14).
Calculate 7, para18 (step 24).

para15 = {(X7−X8) −X axis direction movement amount XA} / X axis direction movement amount
XA …… (11) para16 = (Y7−Y8) / X-axis movement XA …… (12) para17 = (X9−X10) / Y-axis movement YA …… (13) para18 = {(Y9− Y10) Y-axis direction movement amount YA} / Y-axis direction movement amount Y
A …… (14) After applying correction by movement to the processing optical system 4,
As shown in FIG. 3 (f), the observation optical system 3 and the processing optical system 4 are simultaneously moved in the X-axis direction by the same distance X-axis movement amount XB as indicated by arrows B1 and B2, and move before and after the movement. Later, it is irradiated with a laser. Next, the laser beam is moved in the Y-axis direction by the same distance YB in the Y-axis direction, and the laser beam is irradiated before and after the movement. At this time, the irradiation center before moving in the X-axis direction is (X11, Y11), the irradiation center after moving in the X-axis direction is (X12, Y12), the irradiation center before moving in the Y-axis direction is (X13, Y13), and the Y-axis is (X)
14, Y14). Then, the correction values para19, para20, para21, p by the movement of the observation optical system 3 with reference to the processing optical system 4
ara22 is calculated by equations (15) to (18) (step 2
Five).

para19 = (X11−X12) / X-axis movement XB …… (15) para20 = (Y11−Y12) / Y-axis movement YB …… (16) para21 = (X13−X14) / X-axis movement Amount XB ... (17) para22 = (Y13-Y14) / Y-axis direction movement amount YB ... (18) Then, the observation optical system 3 and the processing optical system 4 each have a predetermined coordinate value (XO, YO). The laser beam is moved by applying the movement correction, and the laser is irradiated. The irradiation center after this movement is (X15, Y15)
And Then, the position correction values para23 and para24 of the processing optical system 4 and the observation optical system 3 are calculated by equations (19) and (20) (step 26).

para23 = XO−X15 (19) para24 = YO−Y15 (20) Accordingly, the corrected movement coordinate values (XK, YK) of the observation optical system 3 are required movement amounts (xk, yk) in the X direction and the Y direction. ) Is obtained by the following equations (21) and (22).

XK = (1 + para19) * xk + para21 * yk (21) YK = (1 + para22) * yk + para20 * xk (22) The Z-axis direction is a focus direction.

In the fourth step, the correction of the optical system by moving the position of the stage 5, the X-direction correction value para25 of the observation optical system 3 and the processing optical system 4 based on the position coordinates of the stage 5 [X coordinate of the stage 5] Value / 1
00, Y coordinate value of stage 5/100], Y direction correction value para26
[X coordinate value of stage 5/100, Y coordinate value of stage 5/100]
Is obtained as array data, and the processing optical system 4 is corrected (step 27).

In other words, the movement of the stage 5 should not cause any deviation in the processing optical system and the observation optical system. However, since the mass of the stage is large, a small deviation occurs with the movement. Occurs. To correct this, the X of the stage
A correspondence table between the coordinate values and the Y coordinate values and the correction values is provided in the control unit 2, and the processing optical system is corrected using the correction values corresponding to the coordinate values.

For example, if the coordinate value (X, Y) of the stage is (500, 600), the correction value in the X direction is para25 [5, 6] because it corresponds to the array data element [500/100, 600/100]. The correction value in the Y direction is para26 [5, 6].

Therefore, the corrected movement coordinate values (XP, YP) of the processing optical system 4
Is the required movement amount (xp, yp) in the X and Y directions and the stage 5
The coordinates (XT, YT) are obtained by the following equations (23) and (24).

XP = (1 + para15) * xp + para18 * yp + para23-para25 [XT / 100, YT / 100] ... (23) YP = (1 + para17) * yp + para16 * xp + para24-para26 [XT / 100, YT / 100] ... (24) As described above, the corrected movement amount with respect to the required movement amount of each slit plate 8, 9 is obtained by the obtained equations (5), (6), (9), and (10), and is obtained by the equations (21), (22). A correction movement amount for the required movement amount of the observation optical system 3 is obtained, a correction movement amount for the required movement amount of the processing optical system 4 is obtained by Expressions (23) and (24), and a stepping motor for driving the movement axis of each element is provided. It drives and corrects each.

Effects of the Invention As described above, the present invention provides, as a second step, a movement correction value and a position correction value for each slit plate with respect to the optical axis center of the laser beam obtained in the first step, and a processing optical system as a third step. , The correction value of the movement optical system and the correction value of the movement of the observation optical system, the position correction value of the processing optical system 4 and the observation optical system, and the position correction value of the processing optical system based on the position coordinates of the stage as the fourth step. Since the correction is performed in the order of the fine movement stage of the observation optical system and the processing optical system from the vicinity of the fundamental light source and the coarse movement stage to the stage, there is an effect that the correction can be surely performed. In each process, the error generated by the movement of each element and then the position error between each element are calculated and corrected, so that the slit shape displayed on the monitor screen by image processing etc. There is an effect that the position and the shape of the laser beam coincide with each other.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultraviolet laser processing apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart showing a correction procedure, FIG. 3 (a) is a schematic diagram showing an optical axis correction method,
FIG. 3 (b) is a schematic configuration diagram of the slit plates 8, 9; FIG. 3 (c) is a schematic diagram of a monitor screen after the moving irradiation of the slit plates 8, and FIG. 3 (d) is a slit plate 8, 9; FIG. 3 (e) is a schematic diagram illustrating a method of correcting movement of a processing optical system, and FIG. 3 (f) is a schematic diagram illustrating a position correction method of an observation optical system and a processing optical system. FIG. Explanation of reference numerals of main parts 1 ... Monitor 2 ... Control unit 3 ... Observation optical system 4 ... Processing optical system 5 ... Mounting table 8,9 ... Slit plate

Claims (1)

(57) [Claims] 1. A laser emitting means for emitting an ultraviolet laser, and a plurality of slit plates each moving to a position in accordance with an external command, wherein the ultraviolet laser emitted from the laser emitting means is deformed into a predetermined shape. The variable slit, moved to a position according to an external command, a processing optical system for irradiating the workpiece with an ultraviolet light laser transmitted through the plurality of variable slits, and moved to a position according to an external command. An observation optical system for observing and detecting the irradiation position of the ultraviolet light laser by the processing optical system, and moved to a position according to an external command,
A mounting table on which the workpiece is mounted, and an ultraviolet laser processing apparatus including a position correction unit that performs position correction based on a laser irradiation position detected from the observation optical system, wherein the position correction unit is First position correcting means for correcting the position of each of the plurality of slit plates so that each of the plurality of slit plates is located at a predetermined position with respect to the center of the optical axis, and correcting the position of the processing optical system after the position correction. A second position correcting unit for performing the position correction, a third position correcting unit for performing the position correction of the observation optical system after the position correction, and a third position correcting unit for performing the position correction of the processing optical system by moving the mounting table after the position correction. An ultraviolet laser processing apparatus, comprising: