JPH0396223A - Forming method for soi structure - Google Patents

Abstract

PURPOSE:To extend a lateral epitaxially growing distance and to form a SOI structure having low impurity concentration and large area by suppressing generation of nuclei near a boundary of an a-Si film to an insulating film, injecting an inert element, suppressing generation of nuclei at the surface side of the a-Si film, injecting an active element, and solid growing the a-Si film, etc. CONSTITUTION:A step of forming an insulating film 2 by exposing part of the surface of a single crystalline Si base 1 on the base 1, a step of forming an amorphous Si film 3 on the base 1 and the film 2, a step of suppressing generation of nuclei near a boundary of the film 3 to the film 2 and injecting an inert element, a step of suppressing generation of nuclei at the surface side from a region 3a of the film 3 in which the inert element is injected and injecting an active element, a step of solid growing the film 3 by annealing, and a step of removing a region 3b in which the active element of solid grown Si film 3' is injected are provided. For example, the inert element by suppressing the nuclei includes, for example, F, and the active element by suppressing the nuclei includes, for example, P. The annealing is executed in an N2 atmosphere at 600 deg.C for about 12 hours.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial field of application The present invention is applicable to S O
The present invention relates to a method for forming a Si film using a solid phase growth method.

(b) Conventional technology A structure in which a single crystal Si layer is formed on an insulating layer (including an insulating substrate) is called a Sol structure, and allows for easy element isolation in a narrow area, resulting in high integration and high speed. It is known as something that can be changed. Furthermore, research and development are being actively conducted on semiconductor integrated circuits (ICs) because they offer improved characteristics compared to conventional semiconductor integrated circuits (ICs) in which elements are fabricated on Si substrates.

One of the methods for forming a single crystal Si film on an insulating layer is the solid phase epitaxial elongation method, in which an insulating film is formed on a single crystal Si substrate by exposing a part of the Si substrate surface as a seed. As a result, amorphous Si (hereinafter a) is deposited on the seed and insulating film.
-Si) is deposited and annealed at a low temperature of about 600° C., thereby elongating the solid phase in the lateral direction and converting the a-Si film into a single crystal.

One way to extend the lateral growth distance during solid phase elongation is to implant P1 ions at a high concentration into the a-Si film on the insulating film, and then perform an annealing process.
ed Abstracts of the 16th
Conference on Solid State
Devices and Materials, Ko
be, 1984. (See pp507-510).

However, in order to extend the lateral distance, P1 ions are doped to a high concentration of 3 x 10"cm-", so the impurity (P) concentration in the in-phase monocrystalline Si film is extremely high. Therefore, it has been difficult to fabricate a semiconductor device on this solid phase grown single crystal Si film.

Therefore, by implanting P4 ions only near the surface of the a-Si film deposited on the insulating film, excluding the interface with the insulating film, to cause in-phase growth, and then removing the part where P9 ions were implanted, the impurity concentration It is being considered to obtain a large-area SonI structure with a low (1989, 20th RIKEN Symposium Proceedings, pages 5 to 8).

(c) Problems to be Solved by the Invention However, when P'' ions are implanted only near the surface of the a-Si film to form a solid phase, the region where P has not been introduced will undergo evitaxial elongation. Nuclei that do not inherit the crystal orientation of the seed (single-crystal substrate surface) are likely to occur.For this reason, the generation of such nuclei inhibits the epitaxial growth from the seed, and the entire thickness of the a-Si film is Compared to the case where P is introduced into the region, the lateral epitaxial long distance becomes shorter.

The present invention has been made in view of these points, and has a long lateral epitaxial distance, a low impurity concentration, and
This forms a large-area SO■ structure.

(2) Means for Solving the Problems The present invention includes a step of forming an insulating film on a single crystal Si base by exposing a part of the base surface, and a step of forming an insulating film on the base and the surface of the insulating film.
- a step of forming a Si film, a step of introducing an inactive element to suppress generation of nuclei near the interface with the insulating film of the a-Sill, and introducing the inert element into the a-Si film; a step of suppressing the generation of nuclei and introducing an active element to the surface side of the a-Si film, a step of elongating the a-Si film in a solid phase by annealing, and a step of introducing the active element in the in-phase elongated Si film. This is an Nj method for an SOI structure comprising a step of removing the introduced region.

(e) The nucleus that inhibits the lateral ebitaxial elongation is a-Si
Since it occurs near the interface between the film and the insulating film, by introducing an inert element near that interface to suppress the generation of nuclei, and introducing an active element above that area to suppress the generation of nuclei, Nucleation is suppressed throughout the a-Si film, and at the same time, the lateral solid-phase epitaxial elongation increases in the region where active elements are introduced, so the lateral in-phase epitaxial elongation of the entire a-Si film increases. The long distance increases, and the lateral in-phase epitaxial distance increases. Then, by removing the region into which active elements have been introduced, S with a low impurity concentration is created.
An SOI structure consisting of an i-film is obtained.

(F) Example 1 Figures A to F show a schematic process diagram of an example of the present invention.
In this example, a single-crystal Sf substrate is used as the single-crystal base, but a single-crystal 7Si substrate formed on a substrate such as an insulating substrate
A membrane may also be used.

(1.) is a single-crystal Si substrate as a single-crystal Si base with (100) plane as the main surface, and an insulating film with a thickness of about 500 mm (F) S f O * film (2) is coated on its surface. It is formed by CVD method or thermal oxidation, and is a well-known technique7
Openings (2a) through which the surface of the Si substrate serving as a seed is exposed are formed in a stripe shape in the [001] direction using a trithography technique (FIG. 1A).

Next, after cleaning the substrate, one CVD device (not shown) was installed.
A-Si is deposited on the substrate surface (on the Si substrate (1) surface exposed in the opening (2a) and on the SiOt film (2)).
Film (3) is deposited to a thickness of approximately 600 nm (FIG. 1B).

And a-Si film (3) and SiO! Near the interface with the film (2), F4 ions, which are an inert element that suppresses the generation of nuclei, are implanted at an acceleration energy of 190 keV and a dose of IX101c1'' (FIG. 1C).

The ions to be implanted may be, for example, N4'' ions in addition to F1 ions.

Furthermore, P+ ions, which are active elements that suppress the generation of nuclei, are implanted in a region where F4'' ions are implanted (F dove layer (3)).
Acceleration energy 200 on the surface side (upper side) than a))
keV, dose 4 x 10"cm-", acceleration energy 100keV, dose 1.5 x 10"c
Perform ion implantation overlapping with m-” (Fig. 1D)
. In addition to P" ions, the ions to be implanted include, for example, As" ions.
It may be an ion.

Here, the active element is an element that works to extend the growth distance during solid phase growth, and an element that generates carriers. On the other hand, an inactive element does not generate carriers in the semiconductor layer. Usually, Si in the a-Si film is
When other elements are introduced, the generation of nuclei during solid phase elongation of the a-Si film is suppressed.

As shown in the impurity concentration profile in FIG. 2, as a result of the ion implantation, the a-Si film (3) and SiO! Membrane (2
), and a P-doped layer (3b) in which P is introduced is formed on the F-doped layer (3a).

Next, the substrate is set in an electric furnace and annealed at 600° C. for about 12 hours in a nitrogen (N,) atmosphere. By this annealing treatment, the a-Si on the single crystal Si substrate (1)
The film (3a) is formed using a single crystal Si substrate (1) as a seed.
Solid phase epitaxial growth is performed to form a single crystal Si film (3゛) (FIG. 1E).

At this time, the lateral solid-phase epitaxial growth rate of the entire a-Si film (3) is determined by the thickness of the P dove layer (3b) (approximately 270 to 350 nm in this example), and in this case, approximately 6 X 10-'cm/s, at the same time a-
The element that suppresses the generation of nuclei introduced into the St film (3) suppresses the generation of nuclei (particularly in the a-Si film (3) and SiO film (2)).
(occurrence near the interface with

Finally, the P-doped layer (3b), which is a highly doped impurity layer, is treated with an etchant that removes only this P-doped layer (3b), such as H F : H N O ! 'C Hs
Wet etching is performed using an etchant of C 00H = 1:3:8 to form a single crystal Si film (3') only in the region where inactive elements are introduced and there are few impurities that are inconvenient during device fabrication, and an SOI groove structure is formed. (Figure 1F).

(G) Effects of the Invention As is clear from the above description, the present invention provides an a-Si film and a Sin. Introducing F near the interface with the membrane to suppress the generation of nuclei that inhibit epitaxial elongation near the interface, and introducing P on the upper surface side to accelerate the solid phase epitaxial elongation speed in the lateral direction. In addition, by removing the high impurity concentration region where P is introduced after solid phase elongation, it is possible to create a large area with low impurity concentration that is inconvenient for device fabrication. A single crystal Si film can be formed.

Thus, a substrate with an SOI structure suitable for manufacturing semiconductor devices can be provided, contributing to higher integration and improved characteristics in semiconductor integrated circuits.

[Brief explanation of drawings]

1A to 1F are process explanatory diagrams of an embodiment of the present invention, and FIG. 2 is a diagram showing an impurity concentration profile according to an embodiment of the present invention.

Claims (1)

[Claims] (1) A step of forming an insulating film on a single crystal Si base by exposing a part of the base surface, a step of forming an amorphous Si film on the base and the surface of the insulating film, and a step of forming an amorphous Si film on the base and the surface of the insulating film. A step of introducing an inert element to suppress the generation of nuclei near the interface between the Si film and the insulating film, and a step of introducing an inert element to suppress the generation of nuclei in the vicinity of the interface of the Si film with the insulating film; The method includes a step of suppressing generation and introducing an active element, a step of growing an amorphous Si film in a solid phase by annealing, and a step of removing a region of the solid phase grown Si film into which the active element has been introduced. A method for forming an SOI structure characterized by the following.