JPS6089915A - Preparation of semiconductor thin film - Google Patents

Abstract

PURPOSE:To vary the ratio of maximum and minimum between the beams for obtaining desired intensity distribution, by superposing two convex lenses having the same curvature radius on the same plane and by radiating two-peak beams with the use of a system consisting of these lenses or of the region commonly possessed by these lenses onto a semiconductor thin film. CONSTITUTION:A semiconductor thin film formed on a substrate is recrystallized with energy beams to produce a semiconductor thin film. In this production of semiconductor thin films, two lenses L1 and L2 which are superposed on the same plane are utilized in order to obtain a similar effect as obtained by a composite lens L. Laser beams 2 are radiated in parallel relation against the composite lens L, and the beams 2 incident on each of the lenses L1 and L2 are collected to the focuses F1 and F2, respectively. Further, two laser beams 2 whose optical axes are deflected from each other by a distance (d) are formed, so that the ratio of maximum and minimum between these two-peak beams can be varied. Thus a desired distribution of intensity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a semiconductor thin film formed on a substrate by irradiating a laser beam to recrystallize it. The formed polycrystalline silicon thin film is recrystallized into a single-crystal silicon thin film, and a semiconductor device is manufactured using this single-crystal silicon thin film (I1@80I technology).

For this recrystallization, there is a method in which a laser beam is used to create a bimodal beam, and the polycrystalline silicon thin film is irradiated with this bimodal beam to effect recrystallization. For example, the recrystallization method shown in Fig. 1 changes the shape of the resonant mirror in the Ar radar (1) to convert the beam from the normal TEMoo mode (see Fig. 1C), that is, the beam having a Gaussian distribution intensity. By creating a combination of TEMo and 16M1o modes (see FIG. 1C), the irradiated surface is configured to have a bimodal intensity distribution. al is a mirror.

Laser beam by this recrystallization method (2) Part 5
As shown in Figures 6A and 6B, when the polycrystalline silicon thin film (5) with a thickness of about 0.5μ formed on a glass substrate (4) is scanned, As shown in ), the polycrystalline silicon thin film (5) melted by the laser beam (2) cools and solidifies from the center of the scanning width toward both ends, so that a good single crystal is formed in the center. The silicon region (6) expands. (7) is the bimodal beam irradiated on the polycrystalline silicon thin film (5), 2 is the scanning direction of the bimodal beam, (8) is the polycrystalline silicon region, and (8) is the polycrystalline silicon after recrystallization. This is the silicon area. The recrystallization method shown in FIG.
After being expanded with an up-collimator (9) that is an expander, the light shielding plate 0 has two centrally symmetrical holes 01 formed therein.]
) (see Figure 2B) into two beams (2), and then this beam (2) is made into a narrow beam again by collimator C1, as shown in Figure 2C. It is constructed so that the irradiated surface has a bimodal intensity distribution. According to this method, compared to the method shown in FIG.
There are advantages that the distance between the two peaks can be adjusted by adjusting the distance between the holes a1 of the light shielding plate αυ, and that the valley of the bimodal beam can be made large. The recrystallization method shown in FIG. 3 applies the laser beam (2) to the mirror α1, and
This mirror α1 is connected to a sine wave generator α having a scanner drive circuit.
By vibrating at Φ, the irradiated surface has a bimodal intensity distribution as shown in FIG. 3B. When using this method, the frequency of the mirror (11) is approximately 50
kHz is preferred.

Then, a substrate (
4) from 1 to 20c in the direction perpendicular to the vibration direction of mirror 03.
By moving at a speed of rn/aec, a recrystallized single crystal silicon thin film can be obtained. The recrystallization method shown in FIG. 4 uses a laser beam (2) from an Ar laser (1).
) is incident on a birefringent plate (b) through a mirror 01, and by changing the thickness of this birefringent plate α, bimodal beams of various shapes can be obtained. When using the methods shown in FIGS. 3 and 4 above, there is a problem in that it is difficult to enlarge the depression in the intensity at the center of the bimodal beam.

OBJECTS OF THE INVENTION The present invention enables a bimodal laser beam to be obtained more easily than the above-mentioned conventional recrystallization method, and the intensity distribution of the bimodal laser beam can be easily determined. The present invention provides a method for manufacturing a semiconductor thin film that can be used.

Summary of the Invention The present invention is a semiconductor thin film manufacturing method in which a semiconductor thin film formed on a substrate is recrystallized by a laser beam, in which two convex lenses having the same radius of curvature are superimposed on the same plane. This method of manufacturing a semiconductor thin film is characterized in that the semiconductor thin film is irradiated with a bimodal beam using a lens consisting of both lens portions or a shared portion of both lenses.

According to the present invention, a desired bimodal Radhe beam can be easily obtained.

Example □ An example of the present invention is shown in Figure 7. In the second embodiment, two convex lenses having the same ratio □ radius are overlapped on the same plane.
As shown in the figure, the central part of one convex lens has a width d.
Prepare a pair of lens pieces, I L2, by removing only
It can be made by combining this glue and L2 with a transparent adhesive or the like.

When this composite lens L is irradiated with a laser beam (2), the parallel laser beam (2) incident on L becomes F.
, and the parallel laser beam incident on L2 is focused on F2. In other words, this composite lens LK (5) is composed of two laser beams whose optical axes are shifted by d from each other. The laser beam (2) before entering the combining lens L has a Gaussian intensity distribution with a peak at the center (TEMo).

mode), so □, after passing through this composite lens L, F
A bimodal beam with different intensity distributions is created before and after the -F position. For example, at the position A-A' before F and -F2, the end of the beam that is incident on the center and L2 enters, so the depression in the center as shown in FIG. A bimodal beam with a small value of A bimodal beam with a large depression is obtained.

Therefore, by adjusting the position of the substrate (4) to which the laser beam is irradiated, the irradiated surface can have any bidirectional intensity distribution.

Another embodiment of the invention is shown in FIG. This example corresponds to the case where two convex lenses having the same radius of curvature are superimposed on the same plane and uses a composite lens consisting of both lens parts6) (portion surrounded by a solid line), As shown in the figure, a pair of lens pieces L1 are removed to a distance of d/2 from the center of the convex lens.
It can be made by preparing r L2 and combining this Ll and L2. When this composite lens L' is used, compared to the composite lens L of the above embodiment, the lens piece L1
and L2 each include the center of the lens, so Fl-
At the F2 plane, sharp light can be focused with relatively little spherical aberration.

FIG. 9 schematically shows a laser irradiation device 0Q using the above optical system. This radar irradiation device section uses an Ar laser (1
) is emitted from a laser beam with a diameter of approximately 1n+m (2
) after increasing its diameter with an up-collimator (9),
It is constructed so that the bimodal beam (2) is irradiated onto the υ polycrystalline silicon thin film (5) by making it incident on the composite lens L' according to the present invention. Here, glass piece L
Since the optical axis distance d between 1 and L2 is usually about 100μ,
In this case, after irradiation with the laser beam (2) as shown in Figure 5, a 100μ x 500μ
A monocrystalline silicon region (6) of about 100 mL is formed.

Effects of the Invention According to the present invention, the optical system for creating a bimodal laser beam does not include mechanical movement and has a simple configuration. Further, according to the present invention, the interval between two peaks in the bimodal intensity distribution can be arbitrarily changed at the time of design. Furthermore, since the ratio between the maximum and the minimum between the two peaks in the bimodal intensity distribution can be arbitrarily changed, it is easy to obtain a desired intensity distribution.

[Brief explanation of drawings]

Figures 1 to 4 are diagrams for explaining the conventional recrystallization method, Figure 5 is a diagram showing the laser beam scanning method, Figure 6 is a diagram showing the state of recrystallization of silicon, and Figure 7 8 and 8 are diagrams showing an embodiment of the present invention, and FIG. 9 is a schematic diagram of a laser irradiation device using the optical system according to the present invention. (1) is an Ar laser, (2 is a laser beam, (4)
is a glass substrate, (5) is a polycrystalline silicon thin film, L, L'
is a composite lens. ＜ = Figure 8/ ＼ Figure 9'' Procedural Amendment (Chief Examiner of the Japan Patent Office HL) ■, Display of the case Showa! $8 Patent Application No. 197241 2, Title of the invention Method for manufacturing a conductor thin film 3, Relationship with the case of the person making the amendment Patent applicant address 6-7-35, Kitashina, Tokyo Parts Co., Ltd. Name (21
B) Oga Oga, Representative Director of Sony Corporation 5, Date of amendment order: 6, Showa, Number of inventions increased by 8, Contents of amendment (1) The scope of claims will be amended as shown in the attached sheet. (2) In the specification, page 1, line 14: “Irradiate the beam.”
1 beam or other energy beam.'' (3) Same, page 3, line 19: "About 5QkI-1z J is corrected to "about 59kI-fz or more." Claims A method for manufacturing a semiconductor thin film formed on a substrate and recrystallized by recrystallization,
A semiconductor thin film is irradiated with a bimodal beam using a lens consisting of a portion of both lenses or a shared portion of two convex lenses having the same radius of curvature superimposed on the same plane. A method for manufacturing a semiconductor thin film. 77

Claims (1)

[Claims] In a semiconductor thin film manufacturing method in which a semiconductor thin film formed on a substrate is recrystallized by a laser beam, both lens parts or both lenses when two convex lenses having the same radius of curvature are overlapped on the same plane. A method for producing a semiconductor thin film, comprising irradiating the semiconductor thin film with a bimodal beam using a lens consisting of a shared portion.