JPH0342819A - Laser annealer and laser annealing method - Google Patents

Abstract

PURPOSE:To enable a polycrystalline or amorphous Si at a part with larger heat dissipation such as a seed to be fully fluxed by providing a shutter opening or closing laser light at a high speed into at least a light path of one laser beam in a laser annealer for producing a Silicon on Insulator(SOI) substrate. CONSTITUTION:A high-speed shutter is inserted into a light path of at least one laser beam 2 in an annealer. One part on an Si substrate 11 is left as a seed 16, other parts are oxidized, an SiO2 12 is formed, and a polycrystalline Si 13 is deposited for forming an SOI structure creating substrate. Then, the polycrystalline Si 13 is scanned only by a laser beam 1 using the laser annealer for changing the polycrystalline Si 13 into a single crystal. At that time, a high-speed shutter 5 of the laser beam 2 is opened only when the laser beam 1 scans the seed 16, thus irradiating also the laser beam 2 onto the surface of the polycrystalline Si 13. After that, when the laser beam 1 passes on the seed 16, the high-speed shutter 5 of the laser beam 2 is closed and the surface of the polycrystalline Si 1 3 is irradiated only by the laser beam 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser annealer and a laser annealing method.

(Prior Art) Conventionally, a laser annealing (recrystallization) method has been used as a method for manufacturing an SOI film. In these methods, apparatuses using a large number of laser oscillation tubes have been developed so that large areas can be recrystallized all at once. As an example of this device, Makoto Koyo gave a presentation at the 4th Isolation Functional Element Technology Symposium, in the proceedings of the same (1985) pp237.
-249.

(Problem to be Solved by the Invention) However, with this device, it is not possible to selectively irradiate only a local portion with laser light. Further, when annealing an SOI substrate in which a seed is present, the seed portion is in direct contact with the Si substrate, so heat dissipation from the seed is greater than that on the insulating film, so the optimum annealing conditions for the two are different. Therefore, under conditions that sufficiently melt the polycrystalline Si on the seed, overpowering Si will scatter to the polycrystalline Si on the insulating film. Conversely, under conditions that melt the polycrystalline Si on the insulating film but do not cause scattering of Si due to overpower, the polycrystalline Si on the seed will not melt.

An object of the present invention is to provide a laser annealer and a laser annealing method that solve the above-mentioned problems.

(Means for Solving the Problems) The laser annealer of the present invention uses 5ilicon on In
A laser annealer for producing a 5ulator (SOI) substrate, comprising two or more Ar ion laser oscillation tubes,
The laser beams emitted from the two or more oscillation tubes mentioned above are
It has an optical system configured to be able to irradiate almost the same point on the wafer serving as the I-substrate, and a stage mechanism that allows the aforementioned laser beam to be scanned over the aforementioned wafer. The present invention is characterized in that a shutter capable of opening and closing the laser beam at high speed is provided in the optical path of at least one of the laser beams. Further, the laser annealing method of the present invention is a laser annealing method using this annealer, in which monocrystalline Si is exposed in a part of the Si substrate, but other parts are covered with an insulating film, and , when a laser beam scans a wafer on which polycrystalline Si or amorphous Si is deposited, the polycrystalline Si on the insulating film
The above-mentioned high-speed shutter is in a closed state on i, and the high-speed shutter is open only on single-crystal Si.

(Example) Next, an example of the laser annealer of the present invention will be shown using FIGS. 1 and 2. FIG. 1 is an overall block diagram of the laser annealer. The laser beams emitted from the two Ar ion laser oscillation tubes 1 and 2 have their optical paths bent by various mirrors 7 and are guided onto the wafer 6.

The laser beam can be scanned over the wafer 6 by a stage mechanism. This stage may be a mechanism that moves the wafer itself or a mechanism that makes the optical path length (optical system) variable. In the above-described annealer, a high-speed shutter is inserted into the optical path of at least one laser beam (laser beam 2 in this example). This high-speed shutter is an AO element or the like. If the opening and closing of this shutter is controlled by a computer, the laser beam 2 can be irradiated at a desired location on the wafer by setting shutter opening/closing data in advance. Thereby, the irradiated laser beam becomes the sum of laser beam 1 and laser beam 2 only at a certain desired location, and the irradiation intensity can be doubled. The laser annealing method of the present invention will be explained using FIGS. 2(a) to 2(C).

A portion of the Si substrate 11 is left as a seed 16, and the other portion is oxidized to form 5i0212 with a thickness of lpm. After that, polycrystalline 5i13 was deposited at 500OA by LPCVD.
This is deposited to form a substrate for forming an 80I structure (Figure (a)).

Next, using the aforementioned laser annealer, an SOI substrate is prepared. First, by using only laser beam 1, polycrystalline 5i13
Scan the surface and convert polycrystalline 5i13 into a single crystal ((a
)figure). At that time, only when the laser beam 1 scans the seed 16, the high-speed shutter 5 of the laser beam 2 is opened, and the laser beam 2 is also irradiated onto the surface of the polycrystal 5i13 ((b)
figure). After that, when the laser beam 1 passes over the seed 6, the high-speed shutter 5 of the laser beam 2 is closed, and the surface of the polycrystal 5i13 is irradiated with only the laser beam 1 (FIG. (C)). As a result, sufficient laser power can be irradiated to the polycrystalline Si on the seed part, which has large heat dissipation, so that the seed part is sufficiently melted and the polycrystalline Si on 5i0212 is made into a good single crystal by controlling the plane orientation. oxidation without scattering Si.

In this embodiment, polycrystalline Si is used as the film to be made into a single crystal, but amorphous Si may also be used.

(Effects of the Invention) By using the laser annealer of the present invention, high laser power that cannot be obtained with a single laser beam can be applied to a desired position on a wafer. This allows polycrystalline or amorphous S to be used in areas with large heat dissipation, such as seeds.
i can also be sufficiently melted.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a laser annealer according to an embodiment of the present invention, and FIGS. 2(a) to 2(e) are schematic cross-sectional views showing a laser annealing method according to an embodiment of the present invention. In the figure,

Claims (1)

[Claims] 1. Silicon Insulator (SOI)
In a laser annealer for manufacturing a substrate, two or more Ar ion laser oscillation tubes, configured so that laser light emitted from the two or more oscillation tubes described above can be irradiated to almost the same point on a wafer that will become an SOI substrate. and a stage mechanism capable of scanning the above-mentioned laser light over the above-mentioned wafer, and in the optical path of at least one of the above-mentioned two or more laser lights, a A laser annealer featuring a shutter that can open and close the laser beam. 2. In the laser annealing method using claim 1, S
In one part of the i-substrate, single-crystal Si is exposed, but in other parts, the wafer is covered with an insulating film, and polycrystalline Si or amorphous Si is deposited on the surface of the wafer. , when the laser beam shown in Section 1 scans, the above-mentioned high-speed shutter is closed on polycrystalline Si or amorphous Si on the insulating film, and the high-speed shutter is opened only on single-crystalline Si. A laser annealing method characterized by: