JPS627116A - Manufacture of soi single crystal - Google Patents

Abstract

PURPOSE:To form a SOI single crystal having uniform thickness and no void on a desired position with favorable reproductivity by a method wherein an uneven relief is provided on a silicon film applied on a flat insulative film, and a cap film is applied on it. CONSTITUTION:The surface of a single crystalline silicon substrate 1 is oxidized to form a silicon oxide film 2, on which a polysilicon film is deposited to obtain a polysilicon film 3 which is relieved in a strip shape with photoetching method. The surface of the polysilicon film is coated with a silicon oxide film cap 4 as a cap film. A linearly shaped electron beam is scanned on the sample with the sample structure described above along the strip of the polysilicon film to melt and recrystallize the polysilicon film. By doing this, a higher-temperature distribution can be realized in comparison with the thin part of the polysilicon film's thickness, thereby forming a SOI single crystal having uniform thickness and no void with favorable reproductivity.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention melts and solidifies a silicon film using a laser or an electron beam.
The present invention relates to a method for single-crystallizing an inductor on inductor (inductor on inductor) film.

(Prior art and its problems) When obtaining a single crystal using the SOI crystal growth method using a laser or electron beam, the crystal orientation of the SOI crystal can be aligned with the crystal orientation of the substrate by using a sample structure with seeds. This is an effective method for controlling the orientation of SOI crystals.
For example, when a linear electron beam is scanned perpendicularly to a striped seed, voids occur in the SOI film near the seed, making it impossible to obtain an SOI layer with a uniform thickness.

(Hayato et al., Proceedings of the 45th Japan Society of Applied Physics 12P-C-1
1) On the other hand, using a sample with an SOI structure on the entire surface without using a seed can solve the above-mentioned problem of void generation, but it is difficult to use a linear electron beam or laser beam with a relatively wide uniform beam intensity. When the SOI layer is melted and recrystallized using this method, random nucleation occurs in the width direction of the linear beam, making it difficult to control the crystal grains.

(Objective of the Invention) An object of the present invention is to eliminate the problems of the prior art and provide a method for obtaining an SOI single crystal at a desired position with good reproducibility in a sample structure that does not use seeds.

(Structure of the Invention) According to the present invention, when an SOI film is made into a single crystal by melting and assimilating a polysilicon film or an amorphous silicon film, the structure of the SOI film is such that it is deposited on a flat insulating film. A method for producing an SOI single crystal is obtained, characterized in that the silicon film has a relief structure of unevenness, and a structure in which a cap film is attached thereon is used.

(Detailed Description of Configuration) The present invention solves the problems of the prior art by adopting the above-described configuration. First, a flat insulating film is formed on a substrate, a relief-processed polysilicon film or an amorphous silicon film is formed thereon, and a cap film is further attached to obtain an SOI structure. Silicon is melted by irradiating a sample having the above structure with an electron beam. At this time, since the thick portion of the silicon film is heated by heat conduction from the cap film on the side wall, a higher temperature distribution can be realized than the portion where the silicon film is thinner. Therefore, since the solidification of the silicon film occurs from the thin silicon film thickness portion of the relief, a single crystal SOI film is obtained in this region.

In addition, when recrystallizing using a laser beam,
A similar method can be achieved by forming the cap film into a 2-layer structure, using a film that absorbs laser energy as the upper layer, such as a polysilicon film, and using a film as the lower layer, such as a silicon oxide film, that prevents the reaction between the upper film and the silicon film. effect can be obtained.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a sample structure according to an embodiment of the present invention. Reference numeral 1 denotes a single crystal silicon substrate, and a silicon oxide film 2 having a thickness of 1.0 pm was formed by oxidizing the surface of the substrate using a thermal oxidation method. Furthermore, with CVD method etc.
A polysilicon film 3 was obtained by depositing a polysilicon film to a thickness of 1°0 μm and applying relief processing in a stripe shape using a photolithography method. At this time, the period of the relief is, for example, 16 pm, the width of the groove is 8 pm, and the depth is, for example, 0.5 pm.
It was set as m. A silicon oxide film cap 4 with a thickness of 1.0 pm was deposited as a cap film on this polysilicon film.

The polysilicon film was melted and recrystallized by scanning a sample having such a sample structure with an electron beam having a linear shape of 0.3 mm x 5 mm along the stripes of the polysilicon film. The electron beam irradiation conditions at this time were, for example, an acceleration voltage of 15 kV, a beam current of 52 mA, a scanning speed of 50 cm/see, and a substrate temperature of 600°C.

According to the above conditions, the heat generation center 6 is located almost at the center of the cap film, and as a result, in the heating state, as shown in the direction of heat conduction 7, the thick part of the polysilicon film is placed on the upper surface and the cap on the side wall surrounding the polysilicon. This means that the polysilicon film is heated by heat conduction from the film, and a higher temperature distribution is achieved in parts where the polysilicon film is thinner than in parts where it is thicker. Therefore, recrystallization of the SOI film starts from the thinner portion of the polysilicon film. In this way, an SOI single crystal with a uniform film thickness without generation of voids could be produced in this thin portion with good reproducibility within and between wafers. Further, although a polysilicon film was used in this embodiment, an amorphous silicon film could also be used.

(Effects of the Invention) According to the SOI single crystal manufacturing method of the present invention, an SOI single crystal having a uniform film thickness without generation of voids can be manufactured at a desired position with good reproducibility in a sample structure that does not use seeds. can.

[Brief explanation of the drawing]

FIG. 1 shows a schematic cross-sectional view of an SOI sample structure according to an example of the present invention. In the figure, 1... Silicon substrate 2... Silicon oxide film 3... Polysilicon film 4... Silicon oxide film cap 5... Temperature distribution 6... Heat generation center 7... Direction of heat conduction are shown respectively. Engineering: 1゛￥1141・3″r Director Todoroki Tatsu

Claims (1)

[Claims] When an SOI film is made into a single crystal by melting and solidifying a polysilicon film or an amorphous silicon film, the SOI
An SOI characterized in that the film structure is such that the silicon film deposited on a flat insulating layer has an uneven relief structure, and a cap film is deposited thereon.
Single crystal production method.