JP2527016B2 - Method for manufacturing semiconductor film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor film.

[Conventional technology]

In the conventional method of manufacturing a semiconductor film,
A method is known in which an O ₂ film is formed in a predetermined portion, and epitaxial growth is selectively performed only in a portion where a semiconductor layer in a predetermined region is exposed, and overgrowth is laterally formed on a SiO ₂ film (J .Appl.Phys.55 (2) 15, January 1984, p.519, Co
ntrol of lateral epitaxial chemical vapor depositi
on of silicon over insulators).

[Problems to be Solved by the Invention]

In the conventional technology, over-growth is performed on the amorphous insulating film formed on the substrate surface to form a semiconductor in the lateral direction, and SOI (Semic
When obtaining an on-ductor-on-insulator structure, a thin growth film cannot be obtained because the growth progresses in the unnecessary vertical direction.

An object of the present invention is to provide a method for manufacturing a semiconductor film that solves this problem.

[Means for solving the problem]

In order to achieve the above object, the present invention forms a first SiO ₂ film on a p-type silicon substrate and then forms a first opening exposing the p-type silicon substrate. The first epitaxially grown Si film is selectively grown only in the opening, and the first SiO ₂ film and the first epitaxially grown Si film are grown.
A polycrystalline Si film is deposited on the film to secure a cavity region, and a second SiO ₂ film is formed on the polycrystalline Si film.
A _second opening is formed in the O ₂ film so that the polycrystalline Si film is exposed, and the polycrystalline Si film sandwiched between the first and second SiO ₂ films is selectively removed from the second opening. Etching is performed to form a cavity, and the second epitaxial growth is selectively performed in this cavity.
The Si film is grown laterally.

[Action]

With the conventional technique for manufacturing a semiconductor film, it is impossible to obtain a thin grown film by growing more than necessary in the vertical direction. This is because the growth is performed under the condition that the source gas concentration distribution is substantially the same in both the vertical and horizontal directions, and the crystal growth rate is dependent on the plane orientation. As a result, even when the vertical and horizontal growth planes are selected as different planes, the growth rate ratio of each plane becomes the same value as the aspect ratio, and a larger aspect ratio cannot be obtained.

On the other hand, in the present invention, by forming a cavity portion having a preset aspect ratio, by selectively performing epitaxial growth only in the cavity portion,
This makes it possible to grow a semiconductor film having a required aspect ratio.

〔Example〕

Embodiments of the present invention will be described below with reference to schematic diagrams.
FIG. 1 is a schematic sectional view showing a process step of an example.

As shown in FIG. 1 (a), a first SiO ₂ film 14 is formed on the surface of the p-type silicon substrate 12 by wet oxidation at an oxidation temperature of 950 ° C. up to 5000 Å.

Next, as shown in FIG. 1 (b), a first opening 15 is formed in the first SiO ₂ film 14 by a lithography technique, and p
The type silicon substrate 12 is exposed, and the first epitaxially grown Si film 13 is selectively formed only at the first opening 15 at a growth temperature of 85.
0 ℃, SiH ₂ Cl ₂ flow rate 300cc / min, HCl flow rate 500cc / min, pressure 30T
Grow with orr.

Next, as shown in FIG. 1 (c), the polycrystalline Si film 17 was formed under the conditions of a substrate temperature of 600 ° C., a SiH ₄ flow rate of 150 cc / min, and a pressure of 1 Torr.
3000 Å is deposited, and a polycrystalline Si film 17 is formed in an island shape in a required lateral size by a lithography technique.

Next, as shown in FIG. 1 (d), the second SiO ₂ film 19 is deposited on the entire surface of the substrate including the polycrystalline Si film 17, a second opening in the second SiO ₂ film 19 by lithography Forming 21,
Polycrystalline S at substrate temperature 850 ℃, HCl flow rate 500cc / min, pressure 30Torr
Only the i film 17 is selectively gas-etched to form a cavity portion 23 having a preset aspect ratio.

Next, as shown in FIG. 1 (e), a lateral second epitaxial growth Si film 25 is selectively formed in the cavity 23 at a growth temperature of 850 ° C., a SiH ₂ Cl ₂ flow rate of 300 cc / min, and an HCl flow rate of 500 cc / min. Grow at a pressure of 30 Torr.

Finally, as shown in FIG. 1 (f), the second SiO ₂ film 19 is peeled off to form a thin Si film having a desired area.

As a method of forming the cavity in the above embodiment,
Although gas etching is used, it goes without saying that it can also be formed by another method capable of selectively etching only a polycrystalline film (for example, wet etching).

〔The invention's effect〕

If the present invention is applied, it becomes possible to form a single crystal semiconductor film having a required film thickness on an oxide film.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a process of forming a semiconductor film according to an embodiment of the present invention. 12 …… p-type silicon substrate 13 …… first epitaxially grown Si film 14 …… first SiO ₂ film 15 …… first opening 17 …… polycrystalline Si film 19 …… second SiO ₂ film 21 …… Second opening 23 …… Cavity 25 …… Second epitaxially grown Si film

Claims (1)

(57) [Claims] 1. A first SiO ₂ film is formed on a p-type silicon substrate, and then a first opening is formed to expose the p-type silicon substrate, and only the first opening is selectively formed. Growing a first epitaxially grown Si film, depositing a polycrystalline Si film on the first SiO ₂ film and the first epitaxially grown Si film,
The cavity area is secured, and the second SiO ₂ is deposited on this polycrystalline Si film.
Film is formed, the said the second SiO ₂ film as a polycrystalline Si film is exposed to form a second opening, the first, the polycrystalline Si film sandwiched between the second SiO ₂ film Is selectively etched from the second opening to form a cavity, and the second epitaxially grown Si film is selectively grown in the cavity in the lateral direction.