JPH0362924A - Laser annealing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a laser annealing apparatus for manufacturing substrates for semiconductor devices, particularly highly agglomerated, high-speed, high-performance, fully insulated semiconductor integrated circuits, that is, S○■ devices. However, traditional technology company culture Semiconductor integrated circuits are becoming increasingly denser and faster, and the demand for semiconductor integrated circuits with insulation isolation is increasing. Conventionally, in the formation of semiconductor integrated circuits with insulation isolation (for example, polysilicon deposited on an insulator substrate, such as a silicon (Si) wafer with an insulating film formed on the surface),
Poly-Si is single-crystalized by irradiating a laser beam onto the Si wafer (This is done by forming circuit elements on this Si wafer.The conventional laser annealing apparatus will be explained below with reference to Fig. 3). 3 is a block diagram of the most common laser annealing device.

The laser beam L emitted from the laser light source 1 (the optical path of the laser beam L is changed by the total reflection mirror 3 so that it enters the converging lens 4 perpendicularly, and the diameter of the laser beam on the silicon wafer 5 is adjusted by the converging lens 4.) By scanning the x-y stage 6, the entire surface of the silicon wafer 5 is irradiated with laser beam. Since the optical lens 4 is coated with an anti-reflection film to prevent energy loss due to reflection of the laser beam L, the reflected light from the silicon wafer 5 of the laser beam L, so-called return light, is exactly the same as the optical path of the laser beam L. Reverse the optical path without any attenuation Laser light source 1
There was a problem that the laser beam enters the optical resonator and the output of the laser light source becomes unstable, making the single crystallization state unstable.
In view of these points, the present invention aims to provide a laser annealing apparatus in which the laser output is restored and is not affected by light. When laser annealing a substrate, there is an optical path from the laser light source to the semiconductor substrate in which an anti-reflection film is coated on one main surface, and the anti-reflection film is coated on the opposite main surface. This is a laser annealing apparatus in which a glass substrate without any antireflection film is installed so that the surface coated with the antireflection film is on the laser beam incident side.

Effect of the present invention With the above-described configuration, the laser beam emitted from the laser light source is incident on the anti-reflection film coated side of the glass substrate, so that it reaches the semiconductor substrate without being attenuated. Return light (9) The return light enters from the non-surface side of the anti-reflection film, and a portion of the return light is reflected depending on the angle of incidence on the focal plane of the anti-reflection film. Therefore, the angle of incidence of the return light on the glass substrate is adjusted. By doing so,
The following embodiments show that it is possible to reflect the returning light by a desired amount and to solve the problem that the laser output becomes unstable due to the returning light entering the optical resonator of the laser light source. The embodiment will be explained based on the drawings.
The figure is a block diagram of a laser annealing apparatus according to the present invention. are anti-reflection film focal planes 8A and 8B, and glass substrates 2A and 2B are opposite anti-reflection film focal planes 8A and 8B.
It is installed so that the incident angle of the returning light is θi. Therefore, the laser light emitted from the laser light source 1 passes through the glass substrates 2A, 2B, the total reflection mirror 3, and the condensing lens 4 with almost no energy loss, and is irradiated onto a semiconductor substrate, such as a silicon wafer 5. On the other hand, the returning light (firstly, at the focal plane 8B of the anti-reflection film of the glass substrate 2B, a part of it is reflected by the reflectance R (%) corresponding to the incident angle θi, and then also at the focal plane 8A of the anti-reflection film of the glass substrate 2A). The incident angle of the glass substrate used in this example is that part of it is reflected by the reflectance R (%) corresponding to the incident angle θi, and finally R (2-R/100)% of the returned light is reflected. Figure 2 shows the measurement results of reflectance versus θi.For example, R=2
When the glass substrates 2A and 2B are installed so that the laser beam L is 0% and the silicon wafer 5 is irradiated with the laser beam L with an output of 3W from the laser light source 1, 36% of the returned light is on the glass substrate 2A.
, 2B, it is possible to stabilize the laser output during laser irradiation.

As described in detail, according to the present invention, when laser annealing a semiconductor substrate, fluctuations in laser output due to returning light do not occur during laser irradiation, and a laser annealing device that can always produce stable single crystals. has been realized, and its practical effects are extremely significant for the mass production process of single crystallization.

[Brief explanation of drawings]

Fig. 1 shows the block diagram of a laser annealing apparatus according to an embodiment of the present invention. Fig. 2 shows the relationship between the incident angle θi of the returning light and the reflectance R. Fig. 3 is a block diagram of a conventional laser annealing apparatus. . 1...Laser light wind 2A, 2B...Glass substrate 3...Total reflection Miraco 4...Convergent lens X 5.
...Silicon sea urchin I\6...X-Y stage,
? A, 7B...Anti-reflection film coat ffi 8A
, 8B...No anti-reflection film

Claims (1)

[Claims] When laser annealing a semiconductor substrate, an anti-reflection film is coated on one main surface in the optical path from the laser light source to the semiconductor substrate, and the anti-reflection film is coated on the opposite main surface. A laser annealing device in which an uncoated glass substrate is installed so that the surface coated with the antireflection film is on the laser beam incident side.