JPS62190715A - Manufacture of semiconductor thin film crystal layer - Google Patents

Abstract

PURPOSE:To prevent a defect from occurring by increasing the thickness of a portion that the temperature distribution of a semiconductor thin film becomes irregular as compared with other portion at beam annealing time to reduce the shrinkage of the thin film. CONSTITUTION:A silicon oxide film 12 is formed by a CVD method or the like on a single crystal silicon substrate 11, and a striped hole 13 of 2mum of bottom width is formed at the film 12. A polycrystalline silicon film 14 is formed by depositing, for example, a polycrystalline silicon film of 0.6mum on the entire surface by a CVD method or the like and then selectively forming the film of 0.4mum thick by a lifting off method on a portion that a distance from the hole 13 is 30mum or longer. A silicon oxide film 15 is formed thereon. This sample is annealed by scanning a quasi-linear electron beam 16, and single- crystallized by melting and single crystallizing the film 14. Thus, it can prevent a defect due to a shrinkage from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor i'1ml crystal layer in which a semiconductor thin film crystal layer of single crystal silicon or the like is formed on an insulating film.

[Technical background of the invention and its problems]

In recent years, so-called 5OI (silicon film on insulating film) technology has been actively developed in which a semiconductor single crystal layer is formed on an insulating layer by a beam annealing method using an electron beam, a laser beam, or the like. Furthermore, the development of three-dimensional ICs in which elements are formed three-dimensionally is also progressing using this Sol technology. To realize a three-dimensional IC, a semiconductor single crystal layer is formed using SOI technology on elements (lower layer elements) formed on the surface of a semiconductor wafer. Thereafter, a layered structure element is formed by forming an element (upper layer element) on this single crystal layer.

By the way, when forming a semiconductor single crystal layer for forming an upper layer element using an energy beam, crystal growth is performed using the lower semiconductor substrate as a crystal growth seed through an opening in an interlayer insulating film. However, in the conventional sample structure as shown in Figure 3(a), the thermal conductivity of the semiconductor substrate exposed through the opening is significantly different from that of the insulating film, so it is difficult to melt the semiconductor layer with an energy beam. In this case, the temperature distribution at the shoulder portion of the interlayer insulating film becomes significantly non-uniform. For this reason, there is a problem in that the semiconductor layer contracts at the shoulder portion, resulting in a missing portion as shown in FIG. 3(1)). In FIG. 3, 31 is a single crystal silicon substrate, 32 is a silicon oxide film as an interlayer insulating film, 33 is an opening, 34 is a silicon thin film, 35 is a protective film, 36 is an energy beam, and 37 is a missing part. ing.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and its purpose is to reduce the shrinkage of a semiconductor thin film during beam annealing, and to reduce the shrinkage of a semiconductor single crystal without the occurrence of missing parts on an insulating film. It is an object of the present invention to provide a method for manufacturing a semiconductor thin film crystal layer, which allows the layer to be easily created.

[Summary of the invention]

The gist of the present invention is to reduce shrinkage of the semiconductor thin film by forming a portion of the semiconductor thin film where the temperature distribution is non-uniform during beam annealing to be thicker than other portions.

That is, in the present invention, an insulating film having striped openings is formed on a semiconductor substrate, a polycrystalline or amorphous semiconductor thin film is formed on the openings and the insulating film, and then this semiconductor thin film is In the method for manufacturing a semiconductor thin film crystal layer, the semiconductor thin film is melted and recrystallized by scanning an energy beam on the semiconductor thin film, the semiconductor thin film being thicker in the opening and its surrounding area than in other parts. This is a method that allows the formation of

〔Effect of the invention〕

According to the present invention, since the semiconductor thin film on the boundary between the opening and the flat part of the interlayer insulating film is formed thickly, when the semiconductor thin film is melted by an energy beam, even if the temperature distribution is uneven, the semiconductor thin film shrinkage is less likely to occur. □For this reason, it becomes easy to obtain a semiconductor thin film crystal layer without any missing portions.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIGS. 1A to 1C are cross-sectional views showing the manufacturing process of a silicon single crystal layer according to an embodiment of the present invention.

First, as shown in FIG. 1(a), a silicon oxide film (insulating film) 12 with a thickness of 1.3 [μTrL] is deposited on a single crystal silicon substrate (semiconductor substrate) 11 with a plane orientation of (100) by CVD or the like. is formed, and this silicon oxide film 12 has a bottom width of 2 [
[mu]m] stripe-shaped openings 13 are formed. This opening 13 acts as a seed for crystal growth,
It has a tapered shape where the upper side of the opening widens.

Next, as shown in FIG. 1(b), a polycrystalline silicon film (semiconductor thin film) 14 is deposited on the entire surface, and this silicon film 14
The film thickness was set as follows. That is, silicon oxide 1112
0.6 Cμm in the thin part of the upper film], silicon oxide s
! The thick part of the film on No. 12 was set to 1 [μm]. Also,
Opening 1 in the thicker part of the polycrystalline silicon film 14 in front of the striped opening 13 in the beam scanning direction
It was formed so that the distance from No. 3 was 30 μm or more.

Note that the method for forming the polycrystalline silicon film 14 is as follows:
For example, after depositing a polycrystalline silicon film with a thickness of 0.6 [μ7FL] on the entire surface by CVD method, etc., a polycrystalline silicon film with a thickness of 0.4 [μm] is deposited on the areas where the film should be thickened by lift-off method, etc. A crystalline silicon film may be selectively formed. Alternatively, after depositing a polycrystalline silicon film with a thickness of 1 [μ7rL] over the entire surface by CVD or the like, etching is performed by about 0.4Lμm in areas other than those where the film thickness should be increased.

Next, as shown in FIG. 1(C), a polycrystalline silicon film 14 is formed.
A silicon oxide film (protective film) 15 having a thickness of 0.5 [μTrL] is formed thereon. This sample was exposed to the pseudo linear electron beam 1
6, the polycrystalline silicon film 14 was melted and recrystallized to form a single crystal. Here, the pseudo-linear electron beam refers to a uniformly constrained linear beam obtained by deflecting an electron beam with a minute spot diameter in one direction at high speed. By scanning this pseudo-linear electron beam in a direction perpendicular to the high-speed deflection direction, it is possible to perform beam annealing over a relatively large width in the form of a band.

The single-crystal silicon layer thus obtained exhibited good crystal properties, with no cracks caused by shrinkage of the silicon film. In addition, as shown in FIG. 2, -1: ≧, a striped opening in the beam scanning direction in a part of the polycrystalline silicon film 14 that is thicker than other parts of the polycrystalline silicon film 14 in front of the striped opening 13 in the beam scanning direction. Let the distance to part 13 be X, and this distance X be 10, '20.30 [μm], 3
Two samples were prepared, each of which was made into a single crystal by beam annealing, and the occurrence of missing portions was investigated, and the following results were obtained.

That is, when the distance X is 10 [μynl,
The lack of about 10 [μTrL] of the silicon film, which has been a problem in the past, is due to the 100 [μTrL] of the striped opening 13.
This occurred in 2 to 3 locations per day. Further, when the distance X was 20 [μTrL], the occurrence rate of missing parts was 1 to 2 places, and when the distance X was 30 [μ7FL], almost no missing parts were observed.

In other words, the distance
rL] or more, it is understood that the occurrence of missing portions can be prevented.

In this way, according to the method of this embodiment, the silicon oxide film 12
Since the opening 13 and the polycrystalline silicon film 14 near this opening 13 are formed thicker than other parts, this is caused by uneven temperature distribution of the silicon film 14 during beam annealing using an electron beam. Shrinkage can be reduced and the occurrence of missing parts can be prevented. Therefore, a high-quality silicon single crystal layer can be formed on silicon oxide 1!12, which is extremely effective for manufacturing three-dimensional ICs and the like.

Note that the present invention is not limited to the method of the embodiment described above. For example, the distance X from the opening of a portion of the semiconductor thin film that is made thicker than other portions may be determined as appropriate depending on conditions such as the thickness of the semiconductor thin film and the size of the opening.

Furthermore, the above-mentioned distance It may be.

Further, the energy beam is not limited to an electron beam, and a laser beam may also be used. Further, as the semiconductor thin film to be beam-annealed, amorphous silicon can be used instead of polycrystalline silicon, and it is also possible to use other semiconductors. Further, conditions such as the thickness of the insulating film, the shape and size of the striped openings, etc. can be changed as appropriate depending on the specifications. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIGS. 1(a) to (C) are cross sections showing the manufacturing process of a silicon single crystal layer according to an embodiment method of the present invention, and FIG. 2 is a schematic diagram for explaining the operation of the above embodiment method. Figure, 3rd
Figures (a) and (b) are process cross-sectional views for explaining conventional problems. 11... Single crystal silicon substrate (semiconductor substrate), 12.
...Silicon oxidation I! (insulating Ml), 13... opening, 14... polycrystalline silicon film (semiconductor thin film), 15...
...Silicon oxide film (protective film), 16...Electron beam (energy beam).

Claims (4)

[Claims] (1) Forming an insulating film with striped openings on a semiconductor substrate, forming a polycrystalline or amorphous semiconductor thin film on the openings and the insulating film, and a step of forming a film so that the opening and its surroundings are thicker than other parts; and a step of scanning an energy beam on the semiconductor thin film to melt and recrystallize the semiconductor thin film. A method for manufacturing a semiconductor thin film crystal layer, comprising: (2) The distance in the beam scanning direction from the striped opening to the parts of the semiconductor thin film on both sides that are thicker than the other parts is such that the distance from the striped opening to the front in the beam scanning direction is 2. The method of manufacturing a semiconductor thin film crystal layer according to claim 1, wherein the structure is longer than the rear in the scanning direction. (3) The method for manufacturing a semiconductor thin film crystal layer according to claim 1, wherein an electron beam or a laser beam is used as the energy beam. (4) A single crystal silicon substrate is used as the semiconductor substrate, a silicon oxide film is used as the insulating film, and a polycrystalline silicon film or an amorphous silicon film is used as the semiconductor thin film. A method for manufacturing a semiconductor thin film crystal layer.