JPH04186722A - Manufacture of crystalline semiconductor thin film - Google Patents

Abstract

PURPOSE:To obtain a flat crystalline Si film which can control a position and size of crystal grains, eliminate need of laminating a film having a different thermal expansion coefficient for securing flatness and eliminate crystal defect due to stress at the time of fusing and cooling by repeating two cycles of short time laser beam application process. CONSTITUTION:After an amorphous Si film 2 is formed on an insulating base 1, a laser beam 3 is applied to a partial region so that only the partial region is fused and crystallized to from a crystalline region 4. Then after a second amorphous Si film 5 is laminated, the laser beam 3 is again applied to transform the amorphous region with the crystalline region 4 as a seed layer of a seed crystal. Since the crystalline region 4 exists, application of the laser beam 3 allows rearrangement of Si atoms to proceed in a short time within several seconds at the time of cooling with the crystalline region 4 as the center, so that a crystal grain having a large grain diameter with the crystalline region 4 as a center nucleus can be constituted, a position and size of the crystal grain is controlled, flowing of the film at the time of fusing is prevented, a surface of the formed crystalline Si film 6 is flat, and it is not necessary to laminate a film of a different kind from Si.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for manufacturing a crystalline semiconductor thin film,
lator) It is most suitable for use in forming sideways.

[Prior Art] A conventional method for producing crystalline semiconductor IIL is described in Japanese Patent Application Laid-Open No. 61-288413. FIG. 2(a) to FIG. 2(C) are process-order sectional views showing actual examples of the conventional example. A detailed explanation will be given below based on the drawings.

First, as shown in FIG. 2(a), a polycrystalline S1 film 7 is formed on a quartz substrate 12. Next, as shown in FIG. 2(b), after laminating S i 02 B (silicon dioxide 11N) 8, a laser beam 9 is irradiated to melt the polycrystalline S1 film 7, as shown in FIG. 2(C). single crystal S i Ili
The plan was to convert it to 10.

[Problem to be solved by the invention 1 However, in order to obtain the flatness of the single crystal Si film 10, in order to stack the Si film, the laser beam 9 is
This is because absorption and reflection by O21118 occur, and the absorption and reflectance differ depending on the film quality and thickness of the 5in2111B, as well as its formation conditions.

It is difficult to determine the optimum conditions for the irradiation intensity of the laser beam 9, and the crystallized film is actually a crystalline film in which irregularly shaped crystals are arranged without order, as shown in Figure 3.
It had the problem that it became ll. In addition, the growth of crystal grains occurs from completely random and uncontrollable positions during the heat absorption and heat dissipation process during the laser beam 9 irradiation, so crystal grains that are close to each other can interfere with the crystal growth of the other. However, there is a problem in that it is impossible to realize the growth of large grain size crystals. Furthermore, with the 5iOa film 8,
Part of the laser beam 8 is reflected and absorbed, requiring a high irradiation intensity to melt the polycrystalline Si lli 7, resulting in 5iO = film 8 and crystalline Si film 1
1, and many defects were often generated in the crystalline Sl film 11.

Therefore, the present invention makes it possible to obtain a high-quality semiconductor thin film that is flat, has few defects, and has large crystal grains at predetermined positions without stacking different films on top of the crystallized silicon film. The purpose of the present invention is to provide a method of manufacturing a crystalline semiconductor thin film that is possible.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the method for manufacturing a crystalline semiconductor thin film according to the present invention involves crystallizing an amorphous semiconductor film formed on an insulating substrate. In a method for producing a crystalline semiconductor thin film to obtain a semiconductor film, fii
Step i of forming a first amorphous semiconductor thin film on the insulating substrate, and step zc! irradiating a partial region of the first amorphous semiconductor thin film with a laser beam to form a crystalline region within the first amorphous semiconductor thin film, and then laminating a second amorphous semiconductor thin film; The method is characterized by including a step of bombarding the first amorphous semiconductor thin film and the second amorphous semiconductor thin film with the laser beam to convert them into crystalline semiconductor thin films.

C Example 1 The method for manufacturing a crystalline semiconductor thin film according to the present invention will be described below using SOI.
An example applied to the formation of a structure will be described with reference to the drawings.

First, as shown in FIG. 1(a), an amorphous Si tl! is placed on an insulating substrate l. After forming the (amorphous silicon film) 2, a laser beam 3 is irradiated to a part of the amorphous Si film 2 to melt and crystallize only a part of the amorphous 5iu2, as shown in FIG. ) After laminating the second amorphous 5illi 5 as shown in FIG. The crystalline Si film 6 shown in FIG. 1(d) as
Convert the amorphous region to Due to the presence of the crystalline region 4, the rearrangement of 81 atoms proceeds within a short time of several seconds when the crystalline region 4 is cooled by the irradiation of the laser beam 3, resulting in large grains with the crystalline region 4 as the central core. It consists of crystal grains of diameter. Therefore, the position and size of the crystal grains are controlled, and the crystal grains are not formed in haphazard and uncontrolled positions in the film.Furthermore, the laser beam 3
Since there is a crystalline region 4 that cannot be melted by the irradiation, the flow of the film during melting is also suppressed, and the surface of the formed crystalline 5illi6 remains flat.

Therefore, in order to obtain flatness, there is no need to laminate a film of a different type than Si.

[Effects of the Invention] As explained above, the method for manufacturing a crystalline semiconductor thin film of the present invention repeats the short-time laser beam irradiation process twice to produce a flat crystalline semiconductor thin film in which the position and size of crystal grains can be controlled. This has the effect that a crystalline Sl film can be obtained. Additionally, there is no need to stack films with different coefficients of thermal expansion to ensure flatness.

This has the effect that a high-quality film can be obtained without crystal defects caused by stress generated during melting and cooling.

[Brief explanation of drawings]

1(a) to 1(d) are step-by-step sectional views showing an embodiment of the method for manufacturing a crystalline semiconductor thin film according to the present invention, and FIG. 2(a)
-(C) and FIG. 3 are step-by-step sectional views showing an example of a conventional method for manufacturing a crystalline semiconductor thin film. l... Insulating substrate 2... First amorphous Si ll! 3......
Laser beam 4...Crystalline region 5...Second amorphous Si pus 6...Crystalline Si film or above Applicant: Seiko Epson Corporation Agent Patent attorney Kizobe Suzuki (and 1 others) name) Figure 1

Claims (1)

[Claims] In a method for producing a crystalline semiconductor thin film, in which a polycrystalline semiconductor film is obtained by crystallizing an amorphous semiconductor film formed on an insulating substrate, a first amorphous semiconductor thin film is formed on the insulating substrate. a step of forming the first amorphous semiconductor thin film by irradiating a partial region of the first amorphous semiconductor thin film with a laser beam;
After forming a crystalline region in the amorphous semiconductor thin film, laminating a second amorphous semiconductor thin film, and irradiating the first amorphous semiconductor thin film and the second amorphous semiconductor thin film with the laser beam. A method for producing a crystalline semiconductor thin film, comprising the step of converting the crystalline semiconductor thin film into a crystalline semiconductor thin film.