JPS62142716A - Laser beam processing machine - Google Patents

Abstract

PURPOSE:To scan a laser beam at a high speed with high accuracy and to permit uniform laser beam processing by repeatedly scanning the laser beam by using an acoustooptic element to form the quasi-linear beam having a specified width. CONSTITUTION:The laser beam B irradiated from a CWAr<+> laser 1 is conducted by a reflecting mirror 2 to the acoustooptic element 3. The beam B is scanned in an x-axis direction at the prescribed repetitive frequency and is made quasi- linear by the element 3 which receives the control signal from a control device 7. A sample table 5 is swept in a y-axis direction (perpendicular to the plane of the figure) while such quasi-linear laser beam is condensed by a condenser lens 4 and is irradiated to a silicon wafer 6 after ion implantation which is the work piece provided on the table 5.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a laser beam processing device, and more specifically, to a laser beam processing device that repeatedly scans a laser beam at high speed.

<Prior Art> When attempting to partially heat-treat the surface of an object, there is a method of using a high-power laser beam. A feature of this method is that a limited surface can be selectively heated without increasing the temperature inside the object.

In the above-mentioned radar beam processing equipment that heat-treats the surface of the workpiece with a laser beam, the area hit by the laser beam is not heated uniformly because the intensity distribution within the cross section of the laser beam is uneven. , there was a problem of uneven processing.

Currently, the mainly used laser beam mode is T[
This mode is called the Hoo mode, and the intensity distribution within the cross section of this beam has a Gaussian distribution. For this reason, the temperature distribution of the irradiated part of the workpiece is such that the center of the beam is at a high temperature and the temperature becomes lower toward the periphery. As a result, uneven machining occurs on the workpiece at the center and periphery of the beam.

For example, in a semiconductor process, YAG ray) J' TENo is used to remove defects after ion implantation. mode, even if defects are almost completely removed in the center of the beam,
Defects will remain at the periphery of the beam.

Therefore, ■For example, use the TEHoo mode of a CW Ar+ laser to generate a beam of 10 to 100 nu++/5QCP.
A device that scans at a low speed of once is conceivable.

Furthermore, there is a device that performs laser heat treatment by scanning the beam at high speed with a reflecting mirror to form a quasi-linear beam, and moving the workpiece directly in the scanning direction (U.S. Patent No. 3).
．． 848.104@). This device vibrates a reflecting mirror around a rotation axis at high speed, converts a Radhe beam with uneven cross-sectional power distribution into a pseudo-linear beam with uniform cross-sectional power distribution, and moves metals including carbon etc.
The pseudo-linear beam is irradiated onto the metal surface while being swept by another mirror, and the part of the metal surface that is hit by the beam is $
-1 is melted and hardened.

<Problems to be Solved by the Invention> In the device described in (1) above, considering the cross section perpendicular to the scanning direction of the beam, even if the defect is removed in the area where the center of the beam hits, the peripheral area of the beam is Defects will remain where it hits. Further, when the widths of these beams are overlapped and muffing is performed, defects are not sufficiently removed and remain in the overlapped portion of the beams.

In the device (ii) above, the vibration speed of the photographing mirror is about 300 cycles/second as described in the same specification, which cannot be said to be sufficiently fast, and optical devices such as mirrors and slits Furthermore, since mechanical elements are used to scan the beam, the accuracy of positioning during processing is not very good.

Therefore, there is a problem in that it is not suitable for semiconductor processes that require precision processing. Furthermore, since the mirror is imaged to create a quasi-linear beam, the power will be concentrated at the end of the beam, that is, the rising part of the mirror, and it is necessary to cut this power concentrated part. There is also the issue of becoming.

<Objective of the Invention> The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a laser beam processing device that can scan a laser beam at high speed and with high precision.

Means for Solving the Problems> In order to achieve the above object, the laser beam processing apparatus of the present invention repeatedly scans a laser beam at high speed using an acousto-optic element to form a pseudo line with a constant width. A means for converting the quasi-linear beam into a shaped beam, a means for condensing the quasi-linear beam and irradiating the workpiece, and a means for sweeping the Lede beam or the workpiece in a direction perpendicular to the high-speed repetitive scanning direction. It is 6 that will be done.

Effects> The laser beam processing device with the above configuration uses an acousto-optic element to repeatedly scan the laser beam in a certain direction at high speed, converting it into a quasi-linear beam with a certain width, and condensing this beam. When irradiating a workpiece, if this beam is scanned at a high repetition rate, the irradiated beam 1
Therefore, the intensity distribution is uniform in the high-speed scanning direction. By sweeping the beam or the workpiece in a direction perpendicular to the high-speed scanning direction while scanning this beam, a wide and uniform laser-processed surface can be obtained on the surface of the workpiece.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a diagram showing an outline of a laser beam processing apparatus of the present invention. The device consists of a CWAr+ laser (1), a reflecting mirror (2), an acousto-optic element (3) which is a means of repeatedly scanning a laser beam (B) at high speed and converting it into a quasi-linear beam with a certain width, and a quasi-linear beam. A condensing lens (4) is a means for condensing a shaped beam and irradiating the workpiece onto the workpiece, and a movable sample stage is a means for sweeping the workpiece (6) in a direction perpendicular to the high-speed repetitive scanning direction. (5), a workpiece (6), and a control device (7).

Rede beam irradiated from CWAr+ laser (1)
B) Acousto-optic element (3) by reflecting mirror (2)
guided by. The laser beam (8) is controlled by a control 11 device (
5 by an acousto-optic element (3) that receives a control signal (for example, a control signal in which a sine wave is frequency-modulated) from 1).
It is scanned in the X-axis direction (parallel to the paper surface) at a repetition frequency of 0 k It z to form a primitive line. This linearized laser beam is focused by a condensing lens (4), and is irradiated onto a silicon wafer (6) after ion implantation, which is a workpiece placed on a sample stand (5). (5) is swept in the y-axis direction (perpendicular to the page).

Figure 2(a) shows a laser beam (
B) is shown, and this beam (B) is connected to the sample stage (5
), the width in the X@force direction (Wx) is approximately 500
//I, the width (W,) in the y-axis direction has an extent of about 304.

Figure 2(b) shows the x-
This shows the intensity distribution on the y-plane, showing that the intensity is distributed almost uniformly in the x direction.

Using the above-mentioned radar beam processing equipment, a laser output of 15
Defects in the silicon wafer portion irradiated with W and a sample stage sweep speed of 50 mm/sec were able to be removed evenly.

In the above embodiment, the repetition frequency is 50kHz.
However, by slowing down the sweep speed in the y-axis direction, it is possible to create a quasi-linear beam even if the repetition frequency is set to less than 50kHz. For example, it is possible to form a quasi-linear beam even at a repetition frequency higher than 50 k It z. However, the frequency needs to be lower than the response frequency of the acousto-optic element (3).

<Effects of the Invention> As described above, the laser beam processing device of the present invention can obtain a quasi-linear laser beam with a uniform intensity distribution by irradiating a laser beam at high speed, and can produce a uniform laser beam. It has the unique effect of being able to perform laser beam processing.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of a laser beam processing apparatus according to the present invention, and FIG. 2 is a diagram showing a focused laser beam. (B)... Laser beam, (3)... Acousto-optic element, (4)... Condensing lens, (6)... Workpiece.

Claims (1)

[Claims] 1. Laser beam using an acousto-optic device Scan repeatedly at high speed to create a pseudo image with a constant width. a scanning means for converting the beam into a linear beam; A hand that focuses the beam and irradiates it onto the workpiece. step and perpendicular to the above high-speed repetitive scanning direction. The above laser beam or the above applied and means for sweeping the workpiece. Laser beam processing equipment.