JPH05286U - Laser processing equipment - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the processing speed. [Configuration] Control computer 14 to positioning control circuit 15
A laser irradiation request signal is sent through the laser switching control circuit 2
5, the laser switching control circuit 25 alternately supplies laser irradiation request signals (pulses) to the laser oscillators 18a and 18b, and the laser oscillators 18a and 18b emit laser pulses each time they receive the laser irradiation request signal. The laser pulse from the laser oscillator 18a is reflected by the reflecting mirror 2.
Semiconductor wafer 13 through 1,50% beam splitter 27
The laser pulse from the laser oscillator 18b is reflected by the beam splitter 27 and irradiated onto the semiconductor wafer 13. Used for relieving defective cells of semiconductor memory.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 In this invention, for example, a laser beam pulse is applied to a workpiece by cutting a link on a chip with a laser to repair a defective cell so that an address given to a defective cell in a semiconductor memory is given to a redundant cell. The present invention relates to a laser processing device that irradiates and processes.

[0002]

[Prior Art]

 A conventional laser processing device is shown in FIG. When this is applied to the repair of the defective cell, the stage 12 is mounted on the stage driving mechanism 11, and the semiconductor wafer 13 is arranged on the stage 12. The positioning control circuit 15 is set and controlled by the control computer 14, and the positioning control circuit 15 refers to the position of the stage 12 detected by the stage position detection circuit 16 and drives the stage through the stage drive circuit 17 so as to reach the set position. The mechanism 11 is controlled to control the movement of the stage 12. The laser oscillator 18 is controlled by the control computer 14, the laser light 19 from the laser oscillator 18 is reflected by the reflecting mirror 21 and is incident on the semiconductor wafer 13, and the reflected light is detected by the laser reflected light detector 22. The output of the laser reflected light detector 22 is supplied to the mark detection circuit 23, and the reflected light from the alignment marks formed at the positions corresponding to the four corners of each memory chip on the semiconductor wafer 13 is detected by the mark detection circuit. It is detected at 23, and the detected output is supplied to the control computer 14. After controlling the stage 12 so that the laser light is incident on the position of the link to be cut with this alignment mark as a reference, the power of the laser light is momentarily increased to cut the link.

[0003]

[Problems to be solved by the device]

 The laser processing capacity of this laser processing apparatus, so-called throughput, is determined by the number of laser pulses that can be generated per unit time. With a normal laser oscillator, the number of pulses that can be generated is about 1 KHz, and if the number of pulse repetitions is increased from this, the reproducibility of the pulse waveform and power deteriorates, that is, the stability of the laser pulse decreases and the link breaks. There are cases in which machining is possible and those in which it is not possible, that is, machining cannot be performed correctly. Since the stage can be moved and positioned quickly, the throughput of the laser processing equipment was limited by the maximum repetition frequency at which stable laser pulses were obtained.

[0004]

[Means for Solving the Problems]

 According to this invention, a plurality of laser oscillators are provided, and a laser pulse emission request signal is repeatedly supplied to the plurality of laser oscillators sequentially by the laser switching control circuit, and the laser beam pulses from the plurality of laser oscillators are optically supplied. It is collected by the system into one irradiation light path and is incident on the work piece.

[0005]

【Example】

 An embodiment in which the present invention is applied to a semiconductor memory laser repair apparatus is shown in FIG. 1, and parts corresponding to those in FIG. 3 are designated by the same reference numerals. In this embodiment, a laser oscillator 18a is provided as a laser light source in addition to the laser oscillator 18a, and a laser pulse emission request signal output from the control computer 14 through the positioning control circuit 15 is sent to the laser switching control circuit 25. It is supplied and is repeatedly supplied to the laser oscillators 18a and 18b. A 50% beam splitter (for example, a semi-transparent mirror) 27 is inserted in the laser irradiation optical path 26 from the reflecting mirror 21 to the semiconductor wafer 13 to be processed, and the laser beam 19a from the reflecting mirror 21 is split by the beam splitter 27. The semiconductor wafer 13 is irradiated with the transmitted beam. The laser beam 19b from the laser oscillator 18b is made incident on the beam splitter 27, and the reflected beam thereof reaches the semiconductor wafer 13.

The laser switching control circuit 25 is configured, for example, as shown in FIG. 2A. That is, the laser pulse emission request signal is supplied to the multiplexer 28 and is also supplied to the binary ucanter 31 through the minute delay circuit 29 to be counted. The output of the binary Ucanter 31 controls the multiplexer 28. Therefore, for example, when a laser pulse emission request signal (pulse) as shown in a of FIG. 2B is input to the switching control circuit 25, each request signal of the multiplexer 28 is sent as shown in b and c of FIG. 2B. It is alternately distributed to the two output sides and supplied to the laser oscillators 18a and 18b. Therefore, laser beam pulses 19a and 19b are alternately emitted from the laser oscillators 18a and 18b, respectively, as shown in d and e of FIG. 2B. 2B is combined and the result is as shown in f of FIG. 2B, and the semiconductor wafer 13 is irradiated with the laser beam pulse at the frequency of the laser pulse emission request signal.

However, the frequency of the laser beam pulse emitted from each of the laser oscillators 18a and 18b may be half the frequency of the laser pulse emission request signal. Therefore, it is possible to irradiate the semiconductor wafer 13 with a stable laser beam pulse at a frequency twice as high as the maximum frequency at which a single laser oscillator can emit a stable laser pulse. If the number of laser oscillators is further increased, for example, as shown in FIG. 3, four laser oscillators 18a to 18d are provided, and a laser switching control circuit 25 sequentially supplies a laser irradiation request signal to these laser oscillators 18a to 18d. Then, by collecting the laser beam pulses emitted from these laser oscillators 18a to 18d in one irradiation optical path and irradiating them on the semiconductor wafer 13, the throughput can be quadrupled. The lasers of the laser oscillators 18a to 18b are combined by the reflecting mirror 21 and the beam splitter 27 toward the semiconductor wafer 13 side by the reflecting mirrors 32 and 33, and the lasers of the laser oscillators 18c to 18d are reflected. The light is combined by the mirror 34 and the 50% beam splitter 35, reflected by the reflecting mirror 38, and is incident on the 50% beam splitter 37 inserted between the reflecting mirror 33 and the semiconductor wafer 13. To synthesize. In this way, the lasers of the laser oscillators 18a to 18d reach the semiconductor wafer 13 at the same level.

The present invention can be applied not only to a laser repair apparatus but also to an apparatus that generally processes by a laser pulse.

[0009]

As described above, according to the present invention, the laser irradiation request signal is sequentially and repeatedly supplied to the N laser oscillators to synthesize the laser beam pulses from the N laser oscillators. Since it irradiates the work piece with a laser beam, it can be processed at a speed N times the repetition frequency of the laser pulse that can be stably emitted by one laser oscillator, and the throughput can be increased N times.

[Submission date] August 28, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

However, the frequency of the laser beam pulse emitted from each of the laser oscillators 18a and 18b may be half the frequency of the laser pulse emission request signal. Therefore, it is possible to irradiate the semiconductor wafer 13 with a stable laser beam pulse at a frequency twice as high as the maximum frequency at which a stable laser pulse can be emitted by one laser oscillator. If the number of laser oscillators is further increased, for example, as shown in FIG. 3, four laser oscillators 18a to 18d are provided, and a laser switching control circuit 25 sequentially supplies a laser irradiation request signal to these laser oscillators 18a to 18d. Then, by collecting the laser beam pulses emitted from these laser oscillators 18a to 18d in one irradiation optical path and irradiating them on the semiconductor wafer 13, the throughput can be quadrupled. The lasers of the laser oscillators 18a to 18b are combined by the reflecting mirror 21 and the beam splitter 27 toward the semiconductor wafer 13 side by the reflecting mirrors 32 and 33, and the lasers of the laser oscillators 18c to 18d are reflected. The combined laser is combined by the mirror 34 and the 50% beam splitter 35, reflected by the reflecting mirror 36 , and is incident on the 50% beam splitter 37 inserted between the reflecting mirror 33 and the semiconductor wafer 13. To synthesize. In this way, the lasers of the laser oscillators 18a to 18d reach the semiconductor wafer 13 at the same level.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2A is a block diagram showing a specific example of a laser switching control circuit 25, and B is a time chart showing its operation.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional laser processing apparatus.

Claims (1)

[Claims for utility model registration] 1. A laser processing apparatus for irradiating a workpiece with a laser beam pulse from a laser light source for processing.
A plurality of laser oscillators provided as the laser light source, a laser switching control circuit that sequentially and repeatedly supplies a firing request signal for the laser light source to the plurality of laser oscillators, and a laser beam pulse from the plurality of laser oscillators An optical system that collects in an irradiation optical path, and a laser processing device.