JPH0631476A - Laser processing equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the processing speed without impairing the function of the laser processing equipment. [Structure] When performing processing by irradiating a processing point of an object to be processed on a stage with a laser beam, a minimum distance is calculated from data of the processing point (step 10), and the laser beam is stabilized from this minimum distance. The moving speed of the stage which is as fast as possible within the range of being ejected in such a state and the processing speed can be obtained (step 11), and the processing points are processed sequentially (steps 12, 13, 14, 15, 16, 17).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus.

[0002]

2. Description of the Related Art Conventionally, a stage movable in two orthogonal directions, an alignment device for aligning a wafer on the stage, an interferometer for monitoring the position of the stage, and a laser beam for a processing point of the wafer on the stage. A laser processing apparatus is known which includes a processing laser and an optical system for irradiating a laser beam, and a control device for controlling the position of a stage based on the output of an interferometer and controlling the timing of laser beam irradiation. . In this type of laser processing apparatus, for example, when a plurality of processing points 310 to 314 set on the wafer at unequal intervals are linearly arranged in the X direction as shown in FIG. As shown in the flowchart, first, the stage is moved to two-dimensionally move the irradiation point of the laser beam on the wafer (step 5).
0). At this time, the moving speed of the stage in the X direction is constant. Then, 1 of the coordinates of the machining point already read
Set one (step 51). When the position of the stage coincides with the set coordinates by the output of the interferometer (step 52), a trigger signal is input to the processing laser to cause the laser to emit light (step 53). Processing points 310-314
Since the coordinates of are determined in relation to the output of the interferometer,
The laser emits light when the irradiation point of the laser beam exactly coincides with any of the processing points 310 to 314.
When the laser beam is emitted at all the processing points 310 to 314 (step 54), it is determined that all the processing points 310 to 314 have been processed, the stage is stopped (step 55), and the processing operation is ended.

[0003]

As described above, in the conventional technology, the processing speed cannot be increased because the scanning speed of the stage is fixed. It may be possible to freely set the stage scanning speed in order to increase the processing speed. However, if the stage scanning speed is increased, steps 51, 52,
The processing sequence of 53 and 54 cannot catch up, and it becomes impossible to irradiate the processing point with the laser beam. Furthermore, as the moving speed of the stage is increased, the light emission repetition frequency of the processing laser increases, and the processing laser output becomes unstable.

Therefore, an object of the present invention is to improve the processing speed without impairing the function of the laser processing apparatus.

[0005]

According to the present invention, a minimum distance between processing points can be calculated in advance, a laser beam can be applied to the processing point (the data processing speed can be in time with the movement of the stage), and the processing laser output can be obtained. The scanning speed of the stage is increased within the range where the laser beam is not unstable (the laser beam is emitted in a stable state).

[0006]

[Operation] A laser beam can be applied to the processing point,
In addition, since the scanning speed of the stage is increased within a range where the processing laser output is not unstable, the processing speed can be improved without impairing the function of the laser processing device.

[0007]

FIG. 2 is a block diagram of an apparatus for implementing an embodiment of the present invention. The illumination light for observation from the illumination light source for observation 20 passes through the beam splitters 21, 22 and the objective lens 23, and illuminates the wafer 25 positioned and mounted on the XY stage 24. The wafer 25 is positioned by placing the pre-aligned wafer 25 on an XY stage. The calibration of the wafer 25 with respect to the stage coordinate system is performed by placing the wafer 25 on the stage 24 and then inspecting the alignment mark formed on the wafer 25 by the alignment mark detection means.

The reflected light from the wafer 25 is reflected by the objective lens 2
3. After passing through the half mirror 22, the light is reflected by the half mirror 21 and enters the ITV camera 26, and the wafer 25 is imaged on the photoelectric conversion surface by the objective lens thereof. The video signal obtained by the ITV camera 26 is input to a monitor (not shown), and this monitor displays an image of the surface of the wafer 25.

The laser beam from the processing laser 27 is
After being reflected by the half mirror 22, it is condensed at a predetermined position on the wafer 25 by the objective lens 23. As a result, the predetermined position irradiated with the focused laser beam is processed by the energy of the laser beam. XY stage 24
Are driven by the XY stage drive device 240.

The position of the XY stage 24 is measured by an interferometer 30 having a mirror 29 fixed to the XY stage 24 as a measurement reflection surface. In FIG. 2, the position in the X direction is measured by the mirror 29 and the interferometer 30, but the mirror and the interferometer are similarly provided in the Y direction perpendicular to the paper surface, and the position in the Y direction is measured. It has become so. X
Coordinate signals from the interferometer 30 for coordinate position measurement (and the interferometer for Y coordinate position measurement (not shown)) are input to the control device 28. The controller 28 outputs from the output of the interferometer 30 for measuring the X coordinate position (and the interferometer for measuring the Y coordinate position (not shown)) when the alignment mark detecting means detects the position of the alignment mark on the wafer 25. , Wafer 2
The coordinate system of 5 and the coordinate system of the XY stage 24 are matched.

The control device 30 inputs a signal for driving the XY stage 24 to the XY stage drive device 240, and at the same time, receives the coordinate signal from the interferometer 30 to obtain the wafer 25.
The optical axis of the objective lens 23 (X-
The position of the Y stage 24 on the coordinate system is known in advance)
When the laser beam arrives, a laser beam emission command is issued to the processing laser 27. As a result, the laser beam is emitted from the processing laser 27, and the laser beam is applied to a predetermined position on the wafer 25 through the half mirror 22 and the objective lens 23. It

Next, referring to FIG. 1 showing a flow chart of the control device 28, the operation relating to the processing of the control device 28 will be described. For simplicity of explanation, it is assumed that the processing points are arranged on the wafer 25 at unequal intervals in the X direction, as shown in FIG. That is, in FIG. 3, reference numerals 300, 301, 302, 303, and 304 denote fuses as a workpiece whose longitudinal direction is the Y direction perpendicular to the X direction, and the centers 310, 311, 312, 3 and 3 thereof.
13 and 314 are processing points. By positioning the wafer 25 on the stage, the coordinate position of the processing point is integrally associated with the output of the interferometer 30 for measuring the X coordinate position (and the interferometer for measuring the Y coordinate position (not shown)). To be

Since the data of such a processing point is given in advance (as a design value or an output of the inspection device), the control device 28 is directly input from the data inputted by the operator, the CAD, the inspection device or the like. The minimum distance between the processing points is calculated based on the data (step 10 in FIG. 1). Then,
The time required for the XY stage 24 to move by this minimum distance is as long as possible as long as it is as short as possible as long as it is longer than the minimum emission interval at which the processing laser can stably emit the laser beam. The moving speed in the direction is calculated (step 11 in FIG. 1).

After that, the X-Y stage 24 is moved so as to move in the X direction at the scanning speed calculated in step 11.
A command is issued to the Y stage drive device 240 (step 12 in FIG. 1). Next, of the data of the machining points given in advance, the data of the machining point closest to the scanning start point is set (step 13 in FIG. 1).

When the position of the XY stage 24 coincides with the set machining point data (step 1 in FIG. 1).
4), a laser beam emission command is issued to the processing laser 27 (step 15 in FIG. 1), and when all the processing of the data of the processing points given in advance is not performed (step 16 in FIG. 1), Returning to step 13, the next processing point is set. When all the processing points are processed in step 16 of FIG. 1, it is determined that the processing is completed, and the XY stage 2
4 is stopped (step 17 in FIG. 1).

In the embodiment described above, the minimum distance between the processing points is calculated in advance from the minimum distance between the processing points and the value thereof, and then the stage scanning is started. Therefore, the minimum distance between the processing points is the distance between the other processing points. Even if it is smaller than
Processing points 312 and 313 of FIG. 3) The time t ₃ required for the XY stage 24 to move between the processing points 312 and 313 of FIG. ₃ can be kept longer than the time T required for the processing of steps 13 to 16 of FIG. 1 ( t ₃ > T).

On the contrary, if the embodiment described above is not used, step 13 to step 1 of FIG.
The time T required for 6 becomes longer than the moving time t ₃ between processing points (t ₃ ≦ T), which causes a cause of a miss shot or a cause of unstable processing laser output due to increasing the laser repetition frequency. It will be.

[0018]

As described above, according to the present invention, the effect of improving the overall processing speed can be expected while keeping the processing laser output stable.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing sequence of a control device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a laser processing apparatus used as an embodiment of the present invention.

FIG. 3 is a diagram showing a state of processing points arranged in a straight line.

FIG. 4 is a diagram showing a processing sequence of a conventional laser processing apparatus.

[Explanation of symbols]

 20 Observation Light Source 21, 22 Beam Splitter 23 Objective Lens 24 XY Stage 25 Wafer 26 ITV Camera 27 Processing Laser 28 Control Device 29 Mirror 30 Interferometer 240 XY Stage Drive Device 300-304 Processing Object (Fuse) 310 314 Processing point

Claims (1)

[Claims] 1. A laser processing apparatus for sequentially irradiating a plurality of processing points defined on an object to be processed positioned and mounted on a stage with a laser beam to process the processing points. Of the points, the calculating means for obtaining the minimum distance between the processing points arranged in the moving direction of the stage, and the time for the stage to move the minimum distance obtained by the calculating means are the laser for the processing point. A laser processing apparatus, comprising: a control means for preventing the beam irradiation error and moving the stage at a speed that is as short as possible.