JPS5945996A - Vapor growth of semiconductor - Google Patents

Abstract

PURPOSE:To process a polysilicon film into single crystal, and to obtain a single crystal zone having large area, by pilling simultaneously a polysilicon film on an insulating film and a single crystal film on a substrate of single crystal a vopor growth method, depositing a single crystal silicon film on them. CONSTITUTION:The silicon oxide film (insulating film ) 2 having an pening is formed on the substrate 1 of silicon single crystal, the polysilicon film 3 is piled on the insulating film 2 and the single crystal silicon film 3 is deposited on the substrate exposed to the opening simultaneously by a vapor growth method, the single crystal silicon film 4 is piled at least on the single crystal film 3 and the insulating film 2 around it by the vapor grwoth method, and the polysilicon film 3 under the single silicon film 4 in the pile is processed into single crystal to give the single crystal silicon film 5. By setting proper conditions of pressure, temperature, and ratio fo Si/Cl, enlarged speed of single crystal zone in the width direction much higher than piling speed of the single crystal in the thickness direction can be obtained, and a single crystal zone having large area is prepared.

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.

Integrated circuits using a single crystal semiconductor film on an insulating substrate as an active layer can be easily separated between elements, and parasitic capacitance can be reduced, allowing for higher density and higher speed. Methods of forming a single crystal semiconductor film on an insulating substrate include forming a single crystal semiconductor film on a single crystal insulator substrate such as silicon on sapphire or silicon on spinel, and forming a single crystal semiconductor film on an amorphous insulating substrate. Alternatively, a method of depositing amorphous silicon and recrystallizing it using a beam annealing method such as a laser, or depositing polycrystalline or amorphous silicon on an amorphous insulating substrate and melting it with a heater to recrystallize it. There are ways to do this. Among these, the heteroepitaxial method, in which silicon is epitaxially grown on a single-crystal insulator substrate or on top of a crystal insulator, is basically a method to obtain a single-layer silicon epitaxial film, and single-crystal silicon is formed on an insulator. It is not suitable for one of the major aims of stacking devices on top of each other, so-called three-dimensional devices.

Furthermore, among the methods mentioned above, in the method using recrystallization, 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 large single crystal film.

Although it is limited to cases where seeds can be used, it is also possible to obtain a larger single crystal region by silicon vapor phase epitaxy than by seeds. Compared to the beam annealing method, this method combines the advantages of both methods, such as batch processing like silicon on sapphire and silicon on spinel, and the ability to create a laminated structure like the beam annealing method. There is. However, if this method is grown under normal epitaxial conditions, only a single crystal region almost as large as the seed portion can be obtained. In addition, using a single crystal silicon substrate with a pattern of KSi02 film on the surface, without depositing St on the 5tO2 film, the silicon single crystal film is grown laterally from the seed part, that is, the exposed part of the substrate, that is, on the 5iO1 film. When the growth method of enlarging is used, there is a drawback that in order to obtain a single crystal region of the required size (in the lateral direction), a thickness of approximately 2/3 of the required size (in the lateral direction) is required.

The reason for this is that the contact angle between 8102 and the silicon crystal is large, and the silicon single crystal that is about to stretch has a large contact angle with the silicon.

This is thought to be because it acts to prevent this.

The present invention solves these problems in growing single crystal silicon on an insulating film by vapor phase growth using seeds, and provides a method for obtaining a large single crystal region. be. That is, for a silicon substrate covered with a Sin film having an opening, before growing single crystal silicon, single crystal silicon is deposited on the seed portion, and a polysilicon film is grown on the Sin film using a vapor phase growth method. After that, the growth rate in the thickness direction and the chemical equilibrium conditions were adjusted using pressure, temperature, 5t10A? By setting the ratio to an appropriate condition, it is possible to obtain a rate of expansion of the single crystal region in the lateral direction which is much faster than a deposition rate of single crystal silicon in the thickness direction.

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

Embodiment Figures 1 to 3 are detailed illustrations of the present invention.

FIG. 2 is a diagram sequentially showing schematic cross-sections in main steps when growing a single crystal silicon film on a film. First, P-(10
The surface of the 010z wafer 1 is oxidized with We to a thickness of about 5
An oxide film 2 of 00X was formed. -Next, the entire surface of the wafer is coated with a diameter of 10 mm using conventional photolithography techniques.
The substrate silicon was exposed by a picture 1001trn of μmφ length and width (FIG. 1). At this time, the exposed area of silicon was 3.14% of the total area of one side of the wafer. Next, it was loaded into an infrared heating and reduced pressure epitaxial growth apparatus to deposit a polysilicon film 3 (FIG. 2). The deposition conditions were: pressure 50 TO R, J (2 carriers - gas flow rate 5
ol/min, S iH2012 gas flow-1
ii 600cc/1nin.

The substrate temperature was 825°C. At this time, a polysilicon film is deposited on the Sin film, but a single crystal film is grown on the silicon substrate at the seed portion. After measuring the deposition thickness on the single crystal film to about 500X, the deposition was stopped, and the setting conditions were: pressure 50'l'oI'tR, H2 carrier gas flow rate 851/min, SiH20131 source gas flow rate 560 cc. /min, Hog style fl O,
713/mln, and the substrate temperature was 950°C. When the single crystal silicon film 4 is grown under these setting conditions, the deposition rate is 0.
The speed was 06 μm/min. The expansion rate of the single crystal region in the lateral direction was about 0.29 to 0.32 μm/min. At this time, transmission electron microscope observation of the cross section of the wafer revealed that the polysilicon HJ under the silicon single crystal film had become a single crystal silicon film 5 (FIG. 3). In the case of the present invention, since the contact angle at the interface with 5i02 is not satisfactory, not only the speed of lateral single crystal region expansion increases, but also the polysilicon film becomes single crystal as the episilicon single crystal film expands. It is thought that this contributes to the increase in the expansion speed.

A polysilicon film was still deposited on the polysilicon film in a portion away from the seed portion. The size of the single crystal region obtained depends on the growth conditions, especially the growth rate of the episilicon film.
depended on. In other words, the total thickness of the pre-applied polysilicon film and the polysilicon deposited thereon became thicker, and as the single crystal film expanded, it became difficult to form a single crystal, and the expansion speed suddenly slowed down. Therefore, in order to obtain a larger single crystal area, it is better to deposit the polysilicon film as thinly and uniformly as possible in advance and to slow down the growth rate as much as possible when forming the single crystal silicon film. Growth rate in this example: 0.06 μm/min
, the growth time of 30 minutes is 8.7 from the border of the seed part.
~9. A single crystal region extending in the lateral direction by Fμm was obtained.

Furthermore, according to the results of electron microscope observation, many of the stacking faults that occur at the interface between the 5in2 and the single-crystalline polysilicon film are stuck at the interface with the episilicon crystal film. , the crystallinity of shrimp membranes was improved.

In this example, the Wet9 method was used as the method for forming the oxide film, but the results may be similar with other oxide film forming methods.
The difference in # encoding method is not a problem at all. In this example, Si
n, and the film thickness was set to 500, but there is no restriction on the thickness of the insulating film. In this example, a thermally oxidized 8i02 film was used as the insulating film;
There is no big difference even with N4 film. Further, in this example, a polysilicon film and a single crystal silicon film were formed at the same time. Separate this, coat it with a polysilicon film, and then
- Is the same solution possible even if the substrate silicon is exposed using lithography technology and then a single crystal silicon film is deposited? However, this embodiment is more suitable from an industrial perspective because the number of processes increases. Also, S on the side wall of the seed part.
in.

If it is exposed, the crystallinity of that part will deteriorate.

As described above, the present invention solves the problems of silicon-on-insulators using the conventional vapor phase growth method.
This solution solves the problem of slow lateral expansion rate due to the large contact angle between Si and St, and poor crystallization of the episilicon film on Sin and St, and its industrial value is great.

[Brief explanation of the drawing]

1 to 3 are schematic cross-sectional views for explaining the implementation of the present invention, in which 1 is a silicon single crystal substrate, 2 is a silicon oxide film, 3 is a polysilicon film, 4 is an epitaxial single crystal film, 5 is a polysilicon film, and 3 is a silicon single crystal film that has been monocrystalized during shrimp growth. 3+I concave-)P 2 Kannazu 3 Figure

Claims (1)

[Claims] An insulating film having an opening is formed on a silicon single crystal substrate, and then a polysilicon film is formed on the insulating film 11 by using a vapor phase growth method, and a single crystal silicon film is formed on the substrate exposed in the opening. is simultaneously deposited, and then a single crystal silicon film is deposited by vapor phase growth at least on the single crystal silicon film and on the surrounding insulating film, and during the deposition, the polysilicon under the single crystal silicon film is deposited. A semiconductor vapor phase growth method characterized by forming a film into a single crystal.