JPS6139377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for surface treating an object using a pulsed laser.

In conventional surface treatment apparatuses using pulsed lasers, laser pulses are focused into a spot and irradiated onto an object to perform laser annealing (distortion removal) and laser hardening (hardening).

However, since pulsed lasers generally repeat their oscillations over a short period of time, they have the disadvantage that when the sample is moved, traces of the surface-treated portion are cut off, and there is no continuity between the treated spots on the surface.

On the other hand, if continuous wave lasers are used, at least continuous scanning is possible, but since continuous wave lasers generally have a low laser output, they can melt parts of the surface of metals or semiconductors with good thermal conductivity. It is difficult to

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a surface treatment apparatus using a pulsed laser that can continuously scan while melting spots on the surface of an object sample having good thermal conductivity.

According to this invention, a pulsed laser, an optical deflector, a focusing optical system, and a sample fine movement stage are provided. While this continues, the laser beam is polarized using an optical deflector to scan the sample surface in a linear manner while melting it in a spot shape, and during the subsequent laser pulse oscillation, the sample surface is also melted in a spot shape. However, a surface treatment apparatus using a pulsed laser is obtained, which is characterized in that the scanning line is scanned multiple times in the same direction overlappingly.

According to this invention, there is an advantage that the strain on the sample surface can be released in one direction with directionality. Furthermore, according to this invention, impurities on the surface can be melted and moved in one direction, so it is possible to make a part of the surface particularly highly purified, or to continuously remove impurities from part of the surface. The advantage is that concentration gradients can be created, providing new processing tools for various surface devices.

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

The figure is a block diagram showing an embodiment of a surface treatment apparatus using a pulsed laser according to the present invention.

In the figure, 1 is a pulse laser oscillator, 2 is its power source, and 3 is an optical deflector.

Since it is desirable that the pulse oscillation waveform be a rectangular pulse waveform, the power source 2 controls the excitation input using a pulse shaping circuit network to obtain a laser pulse waveform that is close to a rectangular shape. The appropriate pulse width is from several microseconds to several tens of milliseconds. The optical deflector 3 receives a pulse oscillation start signal from the power source 2 and sweeps in a predetermined direction. As the optical deflector 3, an ultrasonic optical deflector can be used when high-speed scanning is required, and a rotating mirror or a polygon can be used when relatively low-speed scanning is sufficient. Reference numeral 4 denotes a condensing optical system, which uses an aspherical lens designed to minimize aberrations when the laser beam scans the surface of the sample 5. Reference numeral 6 denotes a sample fine movement stage whose position and angle of the sample are variable.

If a plurality of optical polarizing elements are used as the optical deflector 3, the beam can be deflected in both the X and Y directions, so if they are operated simultaneously, the sample surface can be scanned in any direction. However, controlling the deflection direction is generally expensive, so if the required scanning direction is only a straight line rather than a curved line, it is best to adjust the angle of the sample fine movement table in advance and use one deflection element. Scanning may also be performed.

The laser pulse is absorbed by the sample surface, instantly heating the surface layer to a high temperature. If the laser pulse output is too large, the sample surface will evaporate at the focused spot of the laser beam, resulting in laser processing, so adjust the applied laser pulse output just enough to melt the irradiated spot on the sample. do.

During the oscillation duration of a single pulse, the light polarizer 3 scans the light beam in a defined direction. The scanning speed at this time is adjusted to an appropriate speed that is neither too fast nor too slow. If the scanning speed is too fast, the linear region that is irradiated by a single pulse and melted will solidify almost immediately after the pulse irradiation ends, so the strain and impurities contained in the molten region will move in one direction. It is not possible.
On the other hand, if the scanning speed is too slow, heat will move from the surface layer to lower layers due to thermal diffusion, making it difficult to heat treat only the surface layer. Therefore, if the scanning speed is adjusted to such an extent that the previously irradiated spot area begins to solidify just when the laser beam has finished moving about one spot diameter on the sample surface, an appropriate temperature gradient will be created on the surface. Favorable results are obtained.

After completing a single pulse irradiation, the irradiated area on the sample surface is solidified and cooled, and then the pulse irradiation is repeated again to move distortions and impurities on the scanning surface in one direction very efficiently. I can do it.

Suitable samples for surface treatment include metals and semiconductors that have good thermal conductivity and low melting points.
When the width of the linear area to be surface treated is narrow, solidification occurs quickly, so the scanning speed is reduced accordingly.

As described above, the present invention solves the drawbacks of conventional surface treatments using pulsed lasers, such as the generation of scars and discontinuous areas, by scanning the laser beam during the duration of pulsed laser oscillation. According to the present invention, a surface treatment apparatus using a pulsed laser that can move in one direction while melting distortions and impurities on the surface of a sample can be obtained.

[Brief explanation of the drawing]

The drawing is a block diagram showing one embodiment of a surface treatment apparatus using a pulsed laser according to the present invention. 1...Pulse laser oscillator, 2...Power supply, 3...
...Light deflector, 4... Condensing optical system, 5... Sample surface, 6... Sample fine movement stage.

Claims (1)

[Claims] 1. A surface treatment device using a pulsed laser, which includes a pulsed laser device, an optical deflector that deflects the laser beam emitted by this device, and a focusing optical system that focuses the laser beam into a spot on the surface of an object to be irradiated. A surface treatment apparatus using a pulsed laser, characterized in that while a single pulsed laser output continues, the laser beam is scanned by the optical deflector to linearly melt the surface.