JPS627115A - Formation of single crystalline thin film - Google Patents

Abstract

PURPOSE:To widen a margin by a method wherein a microscopic area near a seed is single-crystallized, a crystal is grown on the basis of the microscopic area to melt, solidify and grow only the SOI area so as to meet the annealing condition only in that area. CONSTITUTION:An oxide film 2 is grown on a single crystalline silicon substrate 1, a strip-shaped window is opened on one part of the oxide film 2, and a single crystalline silicon is selectively grown in the inside of the window to be a seed 3. Then, the area is made into a single crystal by forming a silicon film 4 in a striped shape so that the seed 3 is contained in it. Solid-state growth method is used to crystallized the silicon film 4, with which, before the silicon film 4 is applied, the surface of the substrate is cleaned by removing the naturals oxide film on the seed 3 in high vacuum with heating process. After the amorphous silicon film has been formed at the temperature of the substrate 350 deg.C, silicon ion is implanted in the silicon film. After the silicon film has been processed into a striped shape, heat-treatment is performed to grow the single crystalline silicon film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a semiconductor single crystal thin film on an insulating film.

(Prior art and its problems) Single crystal thin film so-called SOI (Semiconductor
When forming a n-ductor on insulating film, it is better to open a window in a part of the insulating film and provide a so-called seed to transmit crystal information from the single crystal substrate to control the crystal orientation of the SOI film. Effective in some cases. However, when forming an SOI film using a seed, the heat dissipation rate is different between the seed part and the other region having the S (M structure). There was a problem that SOI crystals could only be formed under narrow conditions. (Y, Hayafuji, et al.
Electrochemical Society (Electroch)
chemical 5ociety) Extended a
bstruct of 163rd 5ociety
Metting 83-! (1983) P574) For example, in electron beam annealing, the annealing conditions are several percent
The margins were very narrow as they only overlapped to a certain extent. Furthermore, in an SOI sample using a seed, the cooling rate changes in the vicinity of the seed, and the film is also a region with large strain, which makes crystal growth difficult. actual,
Near the seed, subgrains are likely to occur, and S
There is also the problem that voids (holes) are generated in the OI film.

(Objective of the Invention) The present invention solves the above-mentioned problems, expands the conditions for forming SOI crystals when melting and solidifying an SOI film, and eliminates the generation of voids and subgrains in the film. A method for forming a single crystal thin film is provided.

(Structure of the Invention) The present invention forms an insulating film with a window partially formed on a substrate having a semiconductor single-crystal layer on at least the surface, and forms a micro semiconductor layer continuous with the substrate on the insulating film in the window portion. A crystal region is first formed, and then a semiconductor thin film is formed on the sample so as to partially overlap the micro single crystal region, and the semiconductor thin film deposited on the insulating film is melted using the micro single crystal region as a seed. This is a single crystal thin film forming method characterized by solidifying and forming a semiconductor single crystal thin film on an insulating film.

(Detailed explanation of the configuration) Excludes the influence of areas with large changes. Next, crystal growth is performed based on the minute region, but only the SOI vertical region is melted and
Since it is solidified and grown, it is only necessary to match the annealing conditions in the 5OIa region, and a wider margin can be obtained compared to the conventional method. Therefore, the occurrence of subgrains and voids can also be eliminated.

(Examples) Hereinafter, the present invention will be described in detail based on Examples. FIG. 1 shows the method for preparing the sample used in this example. Figure 1 (
As shown in a), an oxide film 2 with a thickness of lpm is grown on a single crystal silicon substrate 1 by a method such as thermal oxidation, a striped window is formed in a part of the oxide film 2, and the inside of the window is exposed. , selectively grown single crystal silicon. This becomes the so-called seed 3. Next, add 0.3pm to include seed 3.
A thick silicon film 4 is deposited in the form of a stripe, and this region is made into a single crystal. At this time, the width 11 of the silicon film 4 was approximately 5 to 20 pm. A solid phase growth method was used to crystallize the silicon film 4. Silikoshi membrane 4″
In a high vacuum of ~lXl0-8Pa before attaching the
The natural oxide film deposited on the seed 3 is heated (approximately 11
00°C) to clean the substrate surface. Next, with a vacuum degree of ~I x 1O-7Pa, the substrate temperature was
After depositing an amorphous silicon film with a thickness of 80° and 4 pm at 0°C, silicon ions t I X 10201/am
Ions were implanted into the silicon film to a concentration of 3. Next, the silicon film was processed into a stripe shape with a radius of 811 m, and then heat treated at 600° C. for 9 hours. It was confirmed using the electron tunneling method that the silicon film 4 was grown as a single crystal by this heat treatment.
came. When using the solid phase growth method, silicon ions were used as the ions to be implanted, but if phosphorus ions are used, single crystal growth is possible up to about 20 pm even under similar heat treatment conditions.

On the other hand, as another method for making the silicon film 4 into a single crystal, an electron beam annealing method was also performed. After depositing polycrystalline silicon, it was processed into stripes with a width of 15 pm to form a silicon film 4. Next, the acceleration voltage was 15 kV, the beam current was 83 mAJ, the scanning speed was 83 cm/sec, and the substrate temperature was 600.
A linear electron beam (beam dimension long side 4 mm) was
After melting, the silicon film 4 was packed and crystallized using the X short side (0.3 mm). At this time, the linear electron beam was scanned in the short side direction thereof, and the scanning direction was set to be the same as the long side direction of the seed. Note that when the silicon film 4 is crystallized by the method described above, two layers of an oxide film and a nitride film are used as a cap film in order to maintain the flatness of the film after crystallization, and after annealing, the cap film is has been removed. When the silicon film 4 is crystallized using solid phase growth as described above, there are no voids. On the other hand, when crystallization is performed using an electron beam, the scanning direction of the electron beam is parallel to the seed, and the width of the silicon layer to be grown is as small as about 15 meters, so when the molten silicon is assimilated. The amount of molten silicon transferred was small, and no voids were observed.

Next, as shown in FIG. 1(b), on the silicon film 4,
A silicon film 6 having a thickness of 0.4 pm was deposited in a striped pattern. The width 12 was several hundred pm. At this time, the conditions for depositing the silicon film 6 were such that the silicon film 4 was epitaxially grown and the oxide film 2 was polycrystalline. For example, normal Si epitaxial growth conditions may be used. Alternatively, MBE of Si may be performed after heating the substrate to about 5006C. Or silicon film 6
In this method, amorphous silicon is deposited, and then heat treatment is performed at a low temperature of about 600°C to form a silicon film 4 by solid phase growth.
Similar results were obtained when a single crystal was grown on top of the material. At this time, the silicon film deposited on the oxide film 2 became polycrystalline. Next, a cap film was deposited over the entire surface of this sample.

The cap film used had a two-layer structure of an oxide film and a nitride film.

Next, the silicon film 6 of such a sample was melted and solidified using a linear electron beam, and crystal growth was performed.

The electron beam annealing conditions include an accelerating voltage of 15 kV,
Beam current 77mA, beam length 4mm, beam width 0.3
A scanning speed of 84 cm/see and a substrate temperature of 600°C were used. Further, the growth direction of the silicon film 6 was perpendicular to the seed 3, and the silicon film 6 was grown from the seed 3 side. At this time, since the silicon film 6 on the silicon film 4 is already monocrystalline (single crystal region 8), the silicon film 6 is only polycrystalline on the oxide film 2. All you have to do is melt and recrystallize. Therefore, as the electron beam annealing conditions, it is sufficient to use the conditions for melting the silicon at the radius 12 on the oxide film 2, and there is no need to melt the seed part at the same time as in the conventional method. This will widen the margin for SOI growth conditions. Furthermore, the region where voids usually occur is the region of the silicon film 4, and when growing the silicon film 6, it is not necessary to melt all of the silicon film 4, and only the portion in contact with the silicon film 6 can be grown. Just melt it. In other words, since areas where heat is not uniformly cooled do not melt, the generation of voids in the silicon film 6 is particularly effective when using a mirror.

(Effect of the invention) Because it does not crystallize, the growth conditions for SOI are expanded, and SOI
The reproducibility of I growth was improved.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional views of a sample showing an example of the present invention. 1...Single crystal silicon substrate 2...Oxide film 3...Seed 4...Silicon film 6...Silicon film 8...Tatsuo Todoroki, Director of the Institute of Industrial Science and Technology, Single Crystal Area

Claims (1)

[Claims] An insulating film with a window partially opened is formed on a substrate having a semiconductor single crystal layer on at least the surface, a micro semiconductor single crystal region continuous with the substrate is first formed on the insulating film from the window part, and then the , a semiconductor thin film is formed on the sample so as to partially overlap the micro single crystal region, and the semiconductor thin film deposited on the insulating film is welded and solidified using the micro single crystal region as a seed, and the semiconductor mono film is deposited on the insulating film. A single crystal thin film formation method characterized by forming a crystal thin film.