JPS5945997A - Vapor growth of semiconductor - Google Patents

Abstract

PURPOSE:To process a polysilicon film into a single crystal, and to obtain a single crystal zone having large area, by filling an opening with a silicon single crystal film, piling simultaneously the polysilicon film on an insulating film and a single crystal film on the single crystal film by a vapor growth method, depositing the single crystal silicon film. CONSTITUTION:The SiO2 film ( insulating film) 2 having an opening is formed on the substrate 1 of silicon single crystal, the opening is filled with the silicon single film 3 by selective epitaxial growth, the polysilicon film 4 is piled on the insulating film 2 and the single crystal silicon film 5 is deposited on the silicon single crystal film 3 simultaneously by a vapor method, the single crystal silicon film is piled at least on the silicon single crystal film 5 and the polysilicon film 4 around it by the vapor growth method, and the polysilicon film 4 under the single crystal silicon film in the pile s processed into single crystal. Silicon on an insulator is obtained by a process only by the enlargement of single crystal zone in the width direction even for a thick insulating film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for growing a silicon epitaxial film in a vapor phase on a single crystal silicon substrate having an insulating film pattern on its surface.

An integrated circuit using a single crystal semiconductor film on an insulating substrate as an active layer is suitable for higher density and higher speed because elements can be easily separated and parasitic capacitance can be reduced. Silicon on sapphire and silicon on sapphire are methods for forming single crystal semiconductor films on insulating substrates.
A method of growing a single crystal semiconductor film on a spinel monocrystalline insulating substrate, a method of depositing polycrystalline or amorphous silicon on an amorphous insulating substrate and recrystallizing it using beam annealing such as a laser, There is a method of depositing polycrystalline or amorphous silicon on an amorphous insulating substrate and melting it with a heater to recrystallize it. Among these, the heteroepitaxial method, in which silicon is epitaxially grown on a single crystal insulating substrate or single crystal insulating film, is basically a method of growing a single layer of St film, and is the main aim of silicon-on-insulator devices. This is a problem when trying to make so-called three-dimensional devices by stacking devices on top of them. Furthermore, among the above-mentioned methods, in the method using n-crystal, the size of the single crystal region is from several microns to several tens of microns at most, regardless of whether the method uses a seed or the method does not use a seed. At present, it is extremely difficult to obtain a larger single crystal film.

It is also possible to obtain a single crystal region larger than that of a seed by silicon vapor phase epitaxy, although this is limited to the case where -75$-dos can be used. Compared to the beam annealing method, this method combines the advantages of both, such as batch processing is possible like silicon on sapphire and silicon on spinel, and it is easy to form a laminated structure like the beam annealing method. There is. However, with this method, if grown under normal epitaxial conditions, only a single crystal region of almost the same size as the seed portion can be obtained. In addition, using a crystalline silicon substrate with a 5iO61147 pattern on the surface, a Sin.

By using a growth method in which St is not deposited on the film and the silicon single crystal film is expanded laterally from the seed portion uII, that is, the exposed part of the substrate, the required dimensions (lateral direction) are To obtain a single-crystal region of 100 mL, a thickness of about 2/3 of that was required. The reason for this is that the contact point between 5i02 and single crystal silicon, the '1 insect angle, is large, and 5i02 acts to prevent the silicon single crystal from elongating. In order to solve this phenomenon, S i
It is effective to coach and inject a thin polysilicon film on the O2 film and then grow the single crystal silicon film. The presence of this polysilicon film accelerates the expansion speed of the shrimp single crystal in the positive direction, and since the polysilicon film crystallizes as a single crystal during shrimp growth, the effect of effectively enlarging the seed area and the single crystal The converted polysilicon film acts as a buffer against crystal defects, and the crystallinity of the epitaxial silicon single crystal film is improved.

By the above-mentioned lateral epitaxial development by vapor phase growth, it has become possible to obtain a single crystal region on an insulating film that is equivalent to or higher than lateral epitaxial growth by recrystallization such as beam annealing. However, such a method has the disadvantage that if the thickness of the insulating layer is increased to reduce the stray capacitance, only a smaller single crystal area can be obtained than in the case of a thin insulating layer. This is because when the insulating film is made thicker, the expansion of the single crystal region must proceed from the substrate silicon through the sidewalls and onto the insulating film, which slows down the expansion of the single crystal region in the lateral direction. Met.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for overcoming these drawbacks and obtaining a silicon onion chelator even with a thick insulating film by a process that involves only expanding the single crystal region in the lateral direction.

According to the present invention, an insulating film having an opening is formed on a silicon single crystal substrate, and then the opening is filled with a silicon single crystal film by selective epitaxial growth.
Next, a polysilicon film is deposited on the insulating film and a single crystal silicon film is simultaneously deposited on the silicon single crystal film by a vapor phase growth method, and then a polysilicon film is deposited on at least the silicon single crystal film and a single crystal silicon film is deposited on the silicon single crystal film by a vapor phase growth method. A method for vapor phase growth of a semiconductor is provided, characterized in that a single crystal silicon film is deposited on the insulating film around the insulating film, and during the deposition, the polysilicon film under the single crystal silicon film is made into a single crystal. It will be done.

The present invention will be explained in detail below according to examples.

1 to 3 are diagrams illustrating embodiments of the present invention, and are diagrams sequentially showing schematic cross-sections in the main steps when growing a single-crystal silicon film on a SiO□ film from a silicon single-crystal substrate serving as a seed. It is.

EXAMPLE The surface of a pH0010Zsi wafer/'1 was oxidized with We to form an oxide film with a thickness of about 50 OA. This 5in
Further, a 2.45 μm thick layer of Si is deposited on the two films using the 0VT method.
Deposit O2 film 2 to make the total thickness of SiO□ film 2.5μ
m and toshida. Next, using normal photolithography technology, the entire surface of the wafer was coated with a diameter of 10 μmφ and a pitch of 10 in the vertical and horizontal directions.
The substrate silicon was exposed at 0 μn1. At this time, the exposed area of silicon was 3.14% of the entire h-evaporation area. Next, the wafer was loaded into an infrared heating and reduced pressure epitaxial growth apparatus, and a single crystal silicon film 3 was selectively taxially grown only in this opening, and the epitaxial silicon thickness was set to 25 μm to flatten the entire surface of the wafer. The conditions for selective epitaxial growth are a pressure of 50T.
ORR, H, carrier gas flow rate 85 l/min.

HOI gas 1.351/min, S 1II
The OA'2 source gas was 560 cc/1 nin, the growth temperature was 1000° C., and the growth time was about 17 minutes. Under these growth conditions, silicon is not deposited on 5iOzl&, but silicon is epitaxially grown only on the 111 opening. At this time, there is a second layer at the interface between the episilicon and the SiO2 film.
As shown in the figure, facets may be formed depending on the surface orientation of the substrate used, but this does not have a major effect on the present invention. Selective growth is stopped when the episilicon thickness at the interface between the episilicon film 3 and the 5i02 film 2 matches the S i OH film thickness as shown in FIG.

Next, the growth conditions were set to a pressure of 50'L! 0RIL, H, carrier gas flow rate 50 l/min, 8 iHtO
Silicon was deposited by setting the A'2 source gas flow rate to 600 cc/min and the substrate temperature to 825°C. At this time, polysilicon Hj4 is deposited on the SiO2 film, but a single crystal film is deposited on the silicon substrate of the seed portion. After the deposition thickness was determined to be approximately 500X by measuring the single crystal film, the deposition was stopped, and the growth conditions were changed to a pressure of 50 TOR'R,
fft carrier gas flow f[t85 l/+nin,
Si'f5. O1t Source gas flow rate 5 G Occ/r
nin, JIOJ style” 40.7 n/rut 11
.

The substrate temperature was changed to 950°C. The growth rate of single crystal silicon under the grain growth conditions was 0.06 μm/min. At this time, the rate at which the single crystal region expanded in the lateral direction from the %t7i10 portion was about 0.31-0.35 μm/+11 inch. 9.3 to 10 from the open end after 30 minutes of growth time.
A single crystal region extending laterally by 5 μm was obtained.

In this example, the insulating layer Sin was made with a film thickness of 2.5 μm, but the key to making the silicon height of the seed part the same as that of the insulating layer film was to increase the speed of expansion of the single crystal region in the same lateral direction. 18. However, if the opening is not filled with episilicon by selective shrimp, the resulting single crystal region 0.
It becomes smaller as the thickness of the insulating film becomes thicker. The rate of decrease e and the insulating film thickness become thicker (J becomes more severe. This is due to the difference between the expansion speed of the single crystal region in the fi11j wall portion and the expansion speed of the single crystal region Ω in the film surface portion. In this example, a silicon substrate with an opening and a film-only structure were used as the starting substrate, but the second
As shown in the figure, the facets provided by this structure create a slight convexity on the surface of the opening. These convex portions can be formed by forming a polysilicon film on only the side wall portions of the 5io2 insulating film as a starting substrate, as shown in FIG. 4, so that facets do not develop and a flat surface can be obtained. It has been confirmed by transmission electron microscopy that the polysilicon film in the present invention is lucidly crystallized. Shiga [7
However, single crystallization does not occur if the same thermal covering history is performed without depositing an episilicon film. That is, in the polysilicon film of the present invention, depending on the episilicon growth conditions and the polysilicon film formation conditions, the polysilicon becomes a single crystal with the help of the episilicon film extending from the seed portion, and the episilicon film is used as a substrate crystal. This contributes to the horizontal expansion of Furthermore, this single-crystal polysilicon film prevents many stacking defects that occur at the interface between the polysilicon film and the polysilicon film at the interface between the polysilicon film and the episilicon film. This contributes to the reduction of These problems are due to the slow lateral growth rate due to the large contact angle between the insulating film and episilicon, which were problems with silicon-on-insulators made using conventional vapor phase growth methods, and the slow lateral growth rate due to the large contact angle between the insulating film and the epitaxial silicon. This solves the problem of poor crystallinity of silicon films.

Further, in this example, selective growth, formation of a polysilicon film, and formation of a single crystal silicon film were performed at the same time, but similar results can be obtained even if these are performed in separate steps. Although Sin is used as the insulating film, similar results can be obtained by using other insulating films, such as a 5t3N4 film.

[Brief explanation of the drawing]

1 to 3 are schematic sectional views for explaining the present invention in detail. FIG. 4 is a schematic cross-sectional view of a wafer in which a polysilicon film is coated on the sidewalls of SiO, H as a starting substrate. The numbers in the figure indicate the following. 1...Silicon substrate 2...5in2 film 3.5-...Silicon single crystal film 4.6...Polysilicon film Attorney ± 1 Mukai Hara Figure 1//℃-I Figure 2 Figure 3 Figure 4-/-1/

Claims (1)

[Claims] An insulating film having an opening is formed on a silicon single crystal substrate, and then the opening is filled with a silicon single crystal film by selective epitaxial growth, and then a polysilicon film is formed on the insulating film by vapor phase growth. A single crystal silicon film is simultaneously deposited on the silicon single crystal +tL Il'rρ, and then a single crystal silicon film is deposited on at least the silicon single crystal film and the insulating film on both sides thereof by a vapor phase growth method. A method for vapor phase growth of a semiconductor, characterized in that the polysilicon film under the single crystal silicon film is monocrystallized during the deposition.