JP2500196Y2 - Laser annealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a laser annealing apparatus for performing heat treatment with a laser beam, and more particularly to a laser annealing apparatus using two laser light sources.

[Conventional technology]

In the conventional laser annealing apparatus, in order to make the focused beam shape at the laser focusing position as wide or flat as possible in the scanning direction, one beam is shaped into an elliptical shape through a cylindrical lens, A birefringent plate is often inserted to split one beam. However, when high speed is pursued, it is considered advantageous to combine two laser beams from two laser light sources. In this case, it is possible to easily change the intensity distribution by adjusting the overlapping amount of the two beams.

[Problems to be Solved by the Invention] By the way, in the above-described method of combining two laser beams by two laser light sources, by combining minutely changing the incident position and angle of the two beams, respective combining is performed. It is possible to change the amount of overlap of the subsequent beams.
However, if the intensities of the respective beams are not balanced, the axial symmetry is lost. In particular, when the non-uniformity occurs in the axis orthogonal to the scanning direction, there is a problem that the annealing state is adversely affected.

The control of the beam intensity balance is usually performed by changing the excitation level of the laser light source. However, when the excitation level of the laser light source is changed, there arise problems that the stability of the laser output is lowered and the intensity distribution of the beam diameter is also changed. Therefore, as a method of controlling the beam intensity balance without changing the excitation level of the laser light source, it is possible to externally attenuate the output to a predetermined value.

For example, in the case of a linearly polarized laser beam, a polarizing plate whose transmitted light intensity can be continuously changed by rotation or a polarizing prism using calcite is used. However, when a polarizing plate is used, the dependence on wavelength is high, and particularly in a laser that oscillates at a plurality of wavelengths such as an argon laser, the insertion loss increases. Further, when a polarizing prism is used, the wavelength characteristic is good, but damage is likely to occur on the joint surface of the prism, and it is not suitable for high output.

On the other hand, a disk-type continuous beam splitter in which a metal thin film is vapor-deposited on optical glass and the transmittance can be controlled by continuously changing the thickness of the thin film can be used regardless of polarization characteristics. However, there is a disadvantage that heat is generated by absorption of the thin film and affects the transverse mode of the laser which is transmitted. Further, if the diameter of the light beam is large, the attenuation will be different at the position of the light beam cross section.

Furthermore, as shown in FIG. 3, by combining a half-wave plate and a polarization beam splitter, and rotating the half-wave plate, the ratio of the polarized components that are transmitted is changed, and the output attenuation factor is changed. It is also possible to control But the normal
In the half-wave plate, the required phase difference can be obtained by adjusting the difference in thickness between the two quartz plates and adjusting the azimuth angle of the optical axis, and therefore has a high dependency on the wavelength. Therefore, when an argon laser or the like is used, there is a problem in that, in addition to the attenuation of the output, the ratio of the internal transmission wavelength changes.

The present invention has been made in view of such circumstances, and an object thereof is to provide a laser annealing apparatus which has a low insertion loss, can be used in a wide band, and can perform high-speed and high-quality annealing.

[Means for solving the problem]

The present invention is provided with two laser light sources and an optical system for combining the laser beams oscillated from the respective laser light sources and simultaneously focusing them on the metal to be annealed to give a thermal change to the metal. The optical system is a half-wavelength Fresnel rom having a rotation mechanism around the optical axis inserted into the optical axes of the two laser beams, a polarizing beam splitter for combining the two laser beams, and a metal to be annealed. A laser output measuring instrument that is placed near the laser beam focusing position to measure the output of the laser beam, and controls the rotation of the Fresnel rom according to the measurement result of this laser output measuring instrument to bring the output to a predetermined value. It has a controller to set the balance of the beam intensity of the two laser light sources according to the output of the optical system. And can be controlled without changing, by reducing the frequency dependence, decrease insertion loss, achieving high-quality and high output, etc., it is to achieve the above object.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing an optical system of a laser annealing apparatus,
FIG. 2 is a diagram showing a polarization action by a combination of a 1/2 wavelength plate and a polarization beam splitter, and FIG. 3 is a diagram showing a 1/2 wavelength Fresnel ROM.

In this embodiment, there are provided two laser light sources 11 and 12, and an optical system 14 that combines the laser beams a and b oscillated from the respective laser light sources and simultaneously focuses them on a sample 13 as a metal to be annealed. are doing. The optical system 14 includes 1/2 wavelength Fresnel roms 15 and 16 each having a rotation mechanism around the optical axis inserted into the optical axes of the two laser beams a and b, and a laser output measuring device for measuring the rotation of these Fresnel roms. A controller (not shown) that controls according to the output of 17 and a polarization beam splitter that combines the two laser beams a and b
18 and. Optical axis adjusting mirrors 19, 20, 21 are provided between the laser light source 11 and the 1/2 wavelength Fresnel ROM 16. Also, a laser light source 12 and a 1/2 wavelength Fresnel ROM 15
Optical axis adjusting mirrors 22 and 23 are provided between and.

Further, a beam expander 24 and an optical axis adjusting mirror 25 are provided between the 1/2 wavelength Fresnel ROM 15 and the polarization beam splitter 18, and between the 1/2 wavelength Fresnel ROM 16 and the polarization beam splitter 18. The beam expander 26
Is provided. Furthermore, polarizing beam splitter
An optical axis adjustment mirror is provided between 18 and the beam reducer 27.
28 and 29 are provided, a beam reducer 27 and an objective lens 30.
An optical axis adjusting mirror 31 is provided between and.

In the above configuration, the laser beams a and b oscillated from the two laser light sources 11 and 12 are respectively reflected by the plurality of optical axis adjusting mirrors 19 to 23, and the 1/2 wavelength Fresnel rom 1
It is incident on 5 and 16. The arrangement of the optical axis adjusting mirrors 19 to 23 is different for each laser beam a and b. this is,
This is because it is necessary to make the polarization planes orthogonal to each other for performing beam combining later by the polarization beam splitter 18.

The diameter of the laser beams a and b is 1/2 wavelength Fresnel ROM 1
After passing 5 and 16, it is expanded by beam expanders 24 and 26. Then, the beams are combined by the polarization beam splitter 18, the beams are incident on the beam reducer 27 in a state of being very close to each other, and the beams are condensed by the objective lens 30 to form the sample 13
To reach.

In order to anneal the sample surface, the sample 13 is placed on an XY stage and moved, or the optical system including the objective lens 30 is moved.

Next, output balance control will be described.

Each laser beam a oscillated from the laser light sources 11 and 12,
b is assumed to be linearly polarized light (S polarized light). As shown in FIG. 2, one of the laser beams a is reflected by the optical axis adjusting mirrors 19, 20, 21 and then polarized by S.
And the polarization of the other laser beam b is P. In the initial state, the half-wave Fresnel roms 15 and 16 are stopped at the angles at which the planes of polarization do not rotate. Therefore, in the polarization beam splitter 18, the laser beam b is incident as it is as P-polarized light, goes straight on the junction surface of the polarization beam splitter 18, and passes through with almost no loss. One laser beam a
Is incident on the polarization beam splitter 18 in the direction orthogonal to the other laser beam b as it is as S-polarized light, is reflected by the cemented surface with almost no loss, and is combined with the laser beam b and output.

When the ratio of the laser beams a and b does not reach the output ratio of 1: 1, the output measuring device 17 installed at the emitting end of the optical system 14
To measure each output. Then, 1 / that is inserted in the optical axis of the larger output of the laser beams a and b
The two-wavelength Fresnel ROM 15 or 16 is rotated by a controller (not shown) via the control means.

Here, when the 1/2 wavelength Fresnel ROM 15 or 16 is rotated by θ, the polarization plane of the incident linearly polarized light is rotated by 2θ, and the ratio of passing or reflecting through the polarization beam splitter 18 is changed, Is branched without being output. Therefore, the output decreases, and it becomes possible to obtain a predetermined value.

According to the embodiment described above, the polarization intensity of the two beam sources is balanced by the polarization beam splitter.
Since 18 and 1/2 wavelength Fresnel ROMs 15 and 16 are used to control 1/2 wavelength Fresnel ROMs 15 and 16 according to the output of the optical system, it becomes possible to control without changing the pumping level of the laser light source, and frequency dependence Is low, insertion loss is low, and high-quality and high-power optical system output can be obtained.

[Effect of device]

As described above, according to the present invention, a laser output measuring instrument for measuring the output of a laser beam and the output is set to a predetermined value by controlling the rotation of the Fresnel rom according to the measurement result of the laser output measuring instrument. Since it is equipped with a controller that controls the beam intensity of the two laser light sources,
It can be controlled without changing the excitation level of the laser light source, its insertion loss is low, and it can be used in a wide band.
The excellent effect that high-speed and high-quality laser annealing can be performed is exhibited.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a laser annealing apparatus according to the present invention, and FIG. 2 is a diagram showing the splitting of light by polarized light when a half-wave plate and a polarizing beam splitter are combined. FIG. 3 is a diagram showing a 1/2 wavelength Fresnel ROM. 11, 12 ... Laser light source, 13 ... Sample (metal to be annealed), 14 ... Optical system, 15, 16 ... 1/2 wavelength Fresnel rom, 17 ... Output measuring instrument, 18 ... Polarizing beam splitter.

Claims (1)

(57) [Scope of utility model registration request] 1. A laser light source comprising two laser light sources, and an optical system for giving a thermal change to the metal to be annealed by combining the laser beams oscillated from the laser light sources and simultaneously focusing them on the metal to be annealed. This optical system is a half-wavelength Fresnel rom having a rotating mechanism around the optical axis inserted into the optical axes of the two laser beams, a polarizing beam splitter for combining the two laser beams, and the annealing. A laser output measuring instrument which is arranged in the vicinity of the condensing position of the laser beam on the target metal and measures the output of the laser beam, and a predetermined output by controlling the rotation of the Fresnel rom according to the measurement result of this laser output measuring instrument And a controller for setting the value of.