JPH034514A - Manufacture of wafer - Google Patents

Abstract

PURPOSE:To obtain a perfect SOI structure having a continuous insulating film by a method wherein a Si single crystal layer is grown on the insulator such as an oxide film, and both an anisotropic etching method and a lateral epitaxial growth method are utilized when a wafer of SOI structure is obtained. CONSTITUTION:A first oxide film 2 is coated on the surface of a Si substrate 1, an unnecessary part is removed by conducting selective etching, and a first aperture part 3 is formed. Then, an epitaxial layer 4 is grown on the whole surface using a lateral epitaxial method while the aperture part 3 is being filled up, the surface of the layer 4 is coated with a second oxide film 5, and a second aperture part 6 corresponding to the first aperture part 3 is perforated using a photolithographic technique. Subsequently, the layer 4 linking between the films 2 and 5 is removed by conducting an RIE method and the like using the remaining film 5 as a mask, and a trench 7 in a blank state is grown between the films 5 and also between the films 2. Then, utilizing the above- mentioned trench 7, a high dosage of ions consisting of oxygen is implanted into the substrate 1 utilizing the trench 7, an annealing treatment is conducted in an inert gas atmosphere, and after the isolated film 2 has been integrated by junction, the film 6 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a wafer having an SOI structure.

[Prior art] S in which a silicon single crystal layer is grown on an insulator such as an oxide film
OI (Silicon On In5ulator)
) Various methods for manufacturing wafers having this structure have been proposed. FIGS. 2(a) to 2(Q) show, as an example, a manufacturing method using lateral epitaxial growth. First, as shown in Fig. 2 (,), a silicon single crystal substrate (hereinafter simply referred to as a silicon substrate) 1 is prepared, and a silicon oxide film (hereinafter simply referred to as an oxide film) 2 is formed on its surface by oxidation treatment. do. Next, as shown in FIG. 2(b), the oxide film 2 is selectively etched away using a normal photolithography technique to form an opening 3 and expose the silicon substrate 1. Subsequently, as shown in FIG. 2(c), a lateral epitaxial growth method is performed to form a silicon single crystal epitaxial layer (hereinafter simply referred to as an epitaxial layer) 4 grown from the silicon substrate 1. That is, by performing the lateral epitaxial growth method, the epitaxial layer 4 that starts growing using the silicon substrate 1 as a seed grows upward from the opening 3 and eventually also grows laterally so as to cover the oxide film 2. . In this case, it is necessary to appropriately set the width W and spacing of the openings 3 in the oxide film 2, and to determine the optimum conditions for the epitaxial growth method so that the single crystal grows also on the oxide film 2 in the lateral direction. This results in a wafer having an SOI structure.

[Problems to be Solved by the Invention] By the way, in the conventional wafer manufacturing method, since the barrier part 3 of the oxide film 2 remains until the end, the oxide film 2 becomes a discontinuous SO.
There is a problem that only the I structure can be obtained.

The present invention has been made in response to the above-mentioned problems.
It is an object of the present invention to provide a method for manufacturing a wafer that can obtain an SOI structure having a continuous oxide film.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a first opening in a first insulating film formed on a semiconductor single crystal substrate, and employs a first lateral epitaxial growth method. a first step of forming a semiconductor single crystal layer continuous with the semiconductor single crystal substrate; forming a second insulating film on the semiconductor single crystal layer; and forming the first opening in the second insulating film. a second opening overlapping the trench, and anisotropically etching the semiconductor single crystal using the second insulating film as a mask to form a trench.
and a third step of implanting oxygen ions using the second insulating film as a mask to form an oxide film in the first opening, and filling the trench with a semiconductor single crystal layer by a second lateral epitaxial growth method. It is characterized by including the steps of.

[Operation] After forming a trench in the semiconductor single crystal layer by anisotropic etching using the second insulating film as a mask, the first insulating film is made continuous by oxidizing the substrate and forming an oxide film. The trench is then filled with an epitaxial layer to complete the SOI structure. This makes it possible to obtain an SOI structure in which an insulating film such as an oxide film is continuous.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a) to 1(j) are process diagrams showing an embodiment of the wafer manufacturing method of the present invention, and the steps will be explained below in order.

First, as shown in FIG. 1(a), a silicon substrate 1 is prepared,
A first oxide film 2 is formed on this surface.

Next, as shown in FIG. 1(b), the first oxide film 2 is selectively etched away to form a first opening 3. Subsequently, as shown in FIG. 1(c), an epitaxial layer 4 is formed by a lateral epitaxial growth method. Note that each of the above steps is the same as the conventional method.

Next, as shown in FIG. 1(d), after performing oxidation treatment to form a second oxide film 5 on the epitaxial layer 4, as shown in FIG. 1(e), a second oxide film 5 is formed using photolithography technology. The oxide film 5 is selectively etched away to form the first opening 3.
The second opening 6 is formed so as to overlap with the second opening 6. In this case, the area of the second opening 6 is made slightly larger than the first opening 3 to prevent misalignment. Subsequently, as shown in FIG. 1(f), using the second oxide film 5 as a mask, the epitaxial layer 4 is anisotropically etched and selectively removed by RIE or the like to form a trench 7.

This anisotropic etching is performed to a depth where the surface of the silicon substrate 1 is exposed through the first opening 3. Next, as shown in FIG. 1(g), a trench 7 is etched using the second oxide film 5 as a mask. After high-dose ion implantation of oxygen into the silicon substrate 1 at an inclination angle of 0 degrees, the surface of the silicon substrate 1 is annealed in a high-temperature inert gas atmosphere, as shown in FIG. The oxide film 2 is oxidized to form the first opening 3.
As a result, the entire surface of the silicon substrate 1 is covered with a continuous first oxide film 2. At this time, since the oxygen ion implantation is performed at an inclination angle of 0 degrees to the silicon substrate 1, that is, perpendicularly, no oxygen is implanted into the side wall portion of the trench 7, so that no oxide film is formed on this side wall portion.

Next, as shown in FIG. 1(i), the epitaxial growth method is performed again to fill the trench 7 with the epitaxial layer 4, and then, as shown in FIG. 1(j), the second oxide film 5 is removed by etching. to complete the SOI structure.

According to this embodiment, the first
The first oxide film 2 is discontinuously formed through the opening 3 of the
can be made continuous by a newly formed oxide film by annealing the silicon substrate 1 into which oxygen ions have been implanted in the step of FIG. 1(g) in the step of FIG. 1(h).

Therefore, a complete SOI structure with a continuous oxide film can be obtained.

In this embodiment, an example in which an oxide film is formed using a silicon substrate has been described, but the present invention is not limited to a semiconductor single crystal substrate and an insulating film, and can be similarly applied.

[Effects of the Invention] As described above, according to the present invention, an SOI structure is manufactured using anisotropic etching and lateral epitaxial growth, so that a complete SOI structure with a continuous insulating film can be manufactured.
I structure can be obtained.

[Brief explanation of drawings]

FIGS. 1(a) to (j) are process diagrams showing an embodiment of the wafer manufacturing method of the present invention, and FIGS. 2(a) to (c) are process diagrams showing a conventional example. 1...Silicon substrate, 2...
...First oxide film, 3...First opening, 4...Epitaxial layer, 5...
. . . second oxide film, 6 . . . second opening, 7 . . . trench.

Claims (1)

[Claims] A first opening is provided in a first insulating film formed on a semiconductor single crystal substrate, and a semiconductor single crystal layer continuous with the semiconductor single crystal substrate is formed by a first lateral epitaxial growth method. forming a second insulating film on the semiconductor single crystal layer, providing a second opening in the second insulating film that overlaps with the first opening; a second step of anisotropically etching the semiconductor single crystal using the insulating film as a mask to form a trench; and implanting oxygen ions using the second insulating film as a mask to form an oxide film in the first opening. and a third step of filling the trench with a semiconductor single crystal layer by a second lateral epitaxial growth method.