JPS61289616A - Manufacture of single-crystal thin film - Google Patents

Abstract

PURPOSE:To prevent a crack from causing in the single-crystal thin film owing to stress by a method wherein the semiconductor layer is formed on the insulator, wherein grooves are formed, and after the semiconductor layer is made to fuse, the semiconductor layer is cooled and is made to recrystallinze. CONSTITUTION:Resists 6 are patterned on an insulator 1, grooves 2 are formed by performing an etching by an RIE method and a semiconductor layer 3 is formed thereon. Then the semiconductor layer 3 is made to fuse by heating using a proper heating means, such as a laser beam 4 to be emitted from the energy source 41 of an Ar laser, for example, and after that, the semiconductor layer is cooled and is made to recrystallize and a single-crystal thin film 5 is obtained. According to this way, the recrystallization is started from the parts of the grooves 2. As a result, a crack can be prevented from causing in the single-crystal thin film 5 during the process of recrystallization.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a thin film single crystal.
It is used in the production of thin film single crystals in the semiconductor industry, for example, 5ol (Silicon o
n In5lator).

[Summary of the invention]

The present invention is a method for forming a thin single crystal semiconductor layer on an insulator, using an insulator with grooves formed thereon, melting the semiconductor layer formed on the insulator, and then cooling and recrystallizing the semiconductor layer. By doing so, it is possible to perform recrystallization from the groove portion and prevent cranking by dividing the semiconductor region with the groove.

[Conventional technology]

Conventionally, thin film single crystals have been obtained by melting the semiconductor layer by irradiating the semiconductor layer with an energy beam or the like and then recrystallizing the semiconductor layer. For example, polycrystalline silicon on an insulator Single-crystal silicon is manufactured by recrystallizing. This is S.O.
It is called S11icon on Insulator (I) technology.

In such Sol technology, when trying to form a single crystal on quartz, for example, as shown in FIG. 5, polycrystalline silicon is simply grown on a quartz substrate a by CVD method, The polycrystalline silicon film is melted by heating means d such as laser beams, infrared rays, and electron beams, and then recrystallized to form a single crystal film e. However, if this is done alone, the film will be cranked due to stress on the film, and normal single crystal silicon will not be obtained. (C in Fig. 5 is the scanning direction of the heating means d.) Although a method known as "recrystallization" in which polycrystalline silicon is separated before melting, stress is alleviated, and then recrystallized is used, there is a need for a method for obtaining a good single crystal more easily.

On the other hand, in order to form a single crystal on an insulator, starting recrystallization from a certain point after melting, seeds (seed crystals) are formed.
Single crystals can be obtained even without it. In order to set a single point on the plane where such recrystallization starts, it is necessary to devise the shape of the polycrystalline silicon, and various such ideas have been used. However, such ingenuity regarding the shape poses a restriction when manufacturing a device in the next process. In other words, the shape setting for starting recrystallization is
This is not preferable because it imposes restrictions on device fabrication.

[Problems to be solved by the invention] As mentioned above, in the conventional technology, it is not always possible to relieve stress and obtain a normal single crystal using simple techniques, and it is difficult to obtain a normal single crystal by relieving stress. There is a problem in that devising the shape for setting becomes a restriction in device production.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to prevent stress from increasing even if a semiconductor is placed on the entire surface of an insulator and melted, so that a desired normal single crystal can be easily produced. Furthermore, the starting point of recrystallization does not impose restrictions on subsequent processing, and therefore, it is possible to provide a pattern with leeway in terms of device fabrication in the subsequent process. The purpose is to provide a manufacturing method.

[Technical means to solve the problem]

As shown in FIG. 1, the method for manufacturing a thin film single crystal according to the present invention includes forming a semiconductor layer on an insulator in which a groove is formed in step I, and melting this semiconductor layer in step 2. After cooling and recrystallization.

In step I, an insulator that originally has a groove may be used, or a groove may be first formed in the insulator (step 1a), and then a semiconductor may be formed on this insulator (step 1b). .

Regarding the configuration of the present invention, a second example showing an example to be described in detail later.
The following will be explained using the examples shown in FIGS. 4 to 4.

First, the insulator 1 with grooves 2 is obtained. In the illustrated example, a resist 6 is patterned on the insulator 1 as shown in FIG.
The insulator 1 is etched to form a groove 2 as shown in FIG. 3. Next, a semiconductor layer 3 is formed thereon.
That’s all the process! It is.

Next, as schematically shown in FIG. 4, the semiconductor N3 is heated by an energy source 41 such as an Ar laser device, etc.
The thin film single crystal 5 is obtained by heating and melting with laser light 4 etc., and then cooling and recrystallizing. Arrow 42 is the scanning direction of the heating means.

[Action of the invention]

According to the present invention, recrystallization is performed from the groove 2 portion.

There is no need to particularly devise a shape to create a starting point, since cooling starts from the bottom of the groove 2, which serves as the starting point. Therefore, it is not necessary to process a shape on a plane, so that subsequent steps such as device manufacturing, etc., are not hindered, and manufacturing with a degree of freedom and leeway is possible.

According to the present invention, cracks are prevented from forming in the film during the recrystallization process. That is, the insulator 1 and the semiconductor layer 2 have different coefficients of thermal expansion, and generally, during the recrystallization process, the semiconductor layer 2 tries to shrink with respect to the insulator 1 and the semiconductor layer 2 is cranked, resulting in a good thin film. Although this means that the crystal 5 cannot be obtained, since the groove 2 is formed in the present invention, this shrinking force is alleviated and the occurrence of cranks is prevented.

This is thought to be because the shrinking force is divided or changes direction at groove 2, so it does not create a large stress.Also, even if stress occurs, it is separated by groove 2, so it is not concentrated and cracks are less likely to occur. -ru.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 to 4. In this embodiment, the present invention will be described in detail below.
This is an example applied to l technology.

In this embodiment, the insulator 1 is quartz. Grooves 2 are formed in this as described above, and polycrystalline silicon is grown on this by low-pressure CVD or the like to form the structure shown in FIG. obtain.

In this embodiment, the following effects are exhibited during melting and recrystallization.

Polycrystalline silicon, which is the material of the semiconductor layer 3, has a different thermal expansion coefficient from quartz, which is an insulator, and since polycrystalline silicon has a larger thermal expansion coefficient, this polycrystalline silicon has a melt diameter recrystallization. During the process, it tries to shrink against quartz. If it is a continuous film, the force will be large enough to break the silicon bonds.
It becomes a crank. As a result, normal single crystal silicon 5 cannot be obtained either. However, if the grooves 2 are formed, racks like this will be less likely to occur.6 The shrinking force on the quartz will be directed in a different direction at the grooves.
This is thought to be because the force is not continuous and the crank does not engage. Moreover, since they are separated by grooves, even if stress occurs, it will be separated by the grooves 2. As a result, stress is not concentrated, but rather a force is applied to the groove 2 that tends to produce a crank, but this is thought to be because the groove 2 is less likely to be damaged and the crank is prevented from entering. However, there is a relationship between cracks and the spacing between the grooves 20, and if the cracks are too wide, there is a tendency for cranks to enter.

Furthermore, when the grooves 2 are formed in this manner and melted and recrystallized, the bottom of the grooves 2 cools down first.

Therefore, recrystallization occurs only from the bottom of groove 2, and this becomes the starting point to form a single crystal. That is, the bottom of groove 2 serves as a seed, and recrystallization occurs in a three-dimensional pattern. The finer the groove 2, the greater this effect, and the groove 2 has a greater effect. ■If grooves are formed, the angle becomes an important factor in crystal growth.

In actual practice, a structure in which a 5ift layer is formed between the insulator 1 made of quartz and the semiconductor layer 3 made of polycrystalline silicon can be used.

〔Effect of the invention〕

As described above, according to the method for producing a thin film single crystal according to the present invention, even when the semiconductor on the insulator is melted and recrystallized, no stress is applied to the film, and in this case, the semiconductor is not applied to the entire surface of the insulator. Even if it is placed on top, cranking due to stress can be prevented. Moreover, in the present invention, this effect can be achieved by the simple means of forming grooves. According to the present invention, the groove can be used as a starting point for recrystallization.
Such a starting point for recrystallization does not impose any restrictions on subsequent processing, and therefore allows for margin and freedom in patterning in subsequent steps.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the present invention. FIGS. 2 to 4 are cross-sectional views showing an embodiment of the present invention in the order of steps. FIG. 5 shows a conventional example. l...Insulator, 2... Groove, 3... Semiconductor layer, 4...
... Heating means (laser light), 5... Thin film single crystal.

Claims (1)

[Claims] 1. A method for manufacturing a thin film single crystal, which comprises forming a semiconductor layer on an insulator in which a groove is formed, melting the semiconductor layer, and then cooling and recrystallizing the semiconductor layer.