JPS636834A - Selective epitaxial growth method - Google Patents

Abstract

PURPOSE:To effectively separate between elements by coating a region except a projection on a single crystal substrate with an amorphous layer, growing a crystal layer on the whole surface on the substrate to miniaturize the formation of the element. CONSTITUTION:A resist pattern 15 is formed on a single crystal substrate 11. A region except an active region of the substrate 11 is etched, and a projection 12 is formed on the active region of the substrate 11. Amorphous GaAs layers 13A, 13B of the same type as the grown molecules are grown on the whole substrate 11. A GaAs layer 13A is lifted off, and a GaAs layer is grown as a crystal layer on the whole substrate 11. Then, a single crystal layer 14A is selectively epitaxially grown on the substrate 11, and a polycrystalline layer 14B is grown on the layer 13B. Accordingly, the layer 14B is not impregnated into the region of the layer 14A to narrow the region of the layer 14A. Thus, the formation of the element is miniaturized to effectively separate between the elements.

Description

[Detailed Description of the Invention] [Summary] In the conventional selective epitaxial growth method, the polycrystalline layer grown on the selective mask material penetrates into the single crystal layer grown on the single crystal, narrowing the single crystal layer region. do. To prevent this, a single crystal layer is grown on the convex portion formed on the substrate.
Furthermore, the stress at the boundary between the single crystal region and the polycrystalline region is reduced by using amorphous tiJ, which has the same molecule as the crystal layer in which the selection mask material is to be grown.

[Industrial application field]

The present invention relates to selective epitaxial growth.

As the semiconductor substrate, a single crystal substrate such as a group III semiconductor such as silicon (Si) or an m-v group compound semiconductor such as gallium arsenide (GaAs) is used.

These substrates can be damage-free, semi-insulating, or
There are high concentrations.

In addition, methods for producing single crystals include the pulling (CZ) method and the floating zone (FZ) method, which create an ingot, which is then sliced and polished to obtain a substrate in the form of a web. .

When creating a semiconductor device, the substrate is rarely used as is, and more often a single crystal layer further epitaxially grown on the substrate is used.

Furthermore, with the advancement of semiconductor devices, a method of selective epitaxial growth on the substrate, growing a single crystal layer in the active region (element formation region) and a polycrystalline layer in the field region (element isolation region), has been used. Became.

The method of epitaxial growth on the surface of a substrate is currently widely used in the production of compound semiconductor devices.

That is, heteroepitaxial layers of semiconductor lasers and photodetectors using the liquid phase epitaxial growth (LPE) method, and high electron mobility devices using the metal organic vapor phase epitaxy (MO-CVD) method or the molecular beam epitaxial growth (formerly ε) method. (H.E.
It is frequently used to form heteroepitaxial layers of MT) and multilayer heteroepitaxial layers such as superlattice elements.

[Conventional technology]

FIG. 3 is a cross-sectional view illustrating conventional selective epitaxial growth.

In the figure, reference numeral 1 denotes a single crystal substrate, on which a silicon dioxide (SiOz) layer 2 is deposited as a selection mask, and an active region for forming elements is opened using ordinary lithography.

When a crystal layer is grown to cover the opening, a single crystal layer 3A is selectively epitaxially grown on the exposed single crystal substrate 1, and a polycrystalline layer 3B is grown on the SiO□ layer 2.

In this case, the single crystal layer 3A grows in one direction only on the single crystal exposed at the bottom of the opening, whereas the polycrystalline layer 3B
Since the growth direction is 270° covering the step of the SiOz layer 2, the polycrystalline layer 3B penetrates into the region of the single crystal layer 3A growing inside the opening, narrowing the region of the single crystal layer 3A.

The region of the polycrystalline layer 3B in contact with the single crystal layer 3A becomes a mismatch region, and this region penetrates into the active region.

Moreover, since the polycrystalline layer 3B is grown on 5 iOz, it has a dull color and is difficult to have a mirror surface.

In this way, quasicrystal I, which becomes the active region of a semiconductor device,
Since the polycrystalline layer 3B penetrates into J3A and the mismatch region is within the active region, it is easy to have ambiguities in device analysis.

Furthermore, there is a problem with the material of the selection mask, and the case of the Sin layer used here, which is easily obtained but has many problems, will be explained.

Generally, if the growing molecules are the same as the single crystal substrate molecules, a single crystal will grow on the substrate with matching, and amorphous or polycrystalline S
Polycrystals grow on iO□.

In this case, the polycrystals grow in any direction and form large grains. These grains do not pose a problem when a thick layer is grown, but when the epitaxially grown layer is as thin as several nanometers, the polycrystalline layer on the SiOz layer becomes an unstable layer even as an element isolation layer.

Furthermore, the epitaxial growth molecules that fly to the mask material and the single crystal surface grow according to different reaction laws, which creates extra stress at the interface between the single crystal region and the polycrystalline region, resulting in an unstable growth layer. .

[Problem that the invention seeks to solve]

In conventional selective epitaxial growth, the polycrystalline N3B in the field region penetrates into the region of the single crystal layer 13A, which becomes the active region, narrowing the region of the single crystal layer 3A, and the interface becomes a mismatched region, which causes excess stress. arise.

[Means for solving problems]

The solution to the above problem is to form a convex portion on a single crystal substrate, to apply an amorphous layer to an area other than the convex portion on the single crystal substrate, and to cover the entire surface of the single crystal substrate. This is achieved by the selective epitaxial growth method according to the present invention, which comprises the steps of: growing a crystalline layer;

When the amorphous layer is made of a substance with the same type of molecules as the crystalline layer to be grown, a stable growth layer can be obtained.

[Operation] By depositing the masking material lower than the single crystal surface, the polycrystalline growth region acts in the direction of correction, and therefore the single crystal region becomes less susceptible to penetration by the polycrystal.

Furthermore, if the mask material is made of an amorphous material having the same kind of molecules as the growing molecules, the single crystal region and the polycrystal region will grow according to the same reaction law, so that no extra stress will be generated at the interface. A physically stable growth layer is obtained.

FIG. 1 is a cross-sectional view illustrating selective epitaxial growth of the present invention.

In the figure, reference numeral 11 denotes a single crystal substrate, which is a semi-insulating gallium arsenide (SI-GaAs) substrate, and a convex portion 12 is formed in the active region on the surface of the single crystal substrate 11, except for the convex portion 12 on the surface of the single crystal substrate 11. amorphous GaAs as a selection mask in the region of
Apply layer 13B.

When the GaAs layer 14 is grown as a crystal layer over the entire surface of the substrate, a single crystal layer 14A is selectively epitaxially grown on the exposed single crystal substrate 11, and a polycrystalline layer 14B is grown on the amorphous GaAs layer 13B.

In this case, the single crystal layer 14A grows on the single crystal exposed on the convex part 12, whereas the polycrystalline layer 14B grows on the single crystal exposed on the convex part 12.
It grows under the step formed by 2.

Therefore, the polycrystalline layer 14B does not penetrate into the area of the single-crystal layer 14A to narrow the area of the single-crystal layer 14A.

The region of the polycrystalline layer 14B in contact with the single crystal layer 14A becomes a mismatch region, but in the case of the present invention, this region is formed outside the active region.

In addition, the mask material is made of amorphous G having the same molecules as the growing molecules.
Since the aAs layer 13B is formed, a stable growth layer can be obtained without generating extra stress at the interface between the single crystal region and the polycrystal region.

[Example] Figures 2 [1] to (5) are cross-sectional views illustrating an example of selective epitaxial growth of the present invention.

In Fig. 2 [1], 11 is a single crystal substrate made of 5I-Ga.
An As substrate is used, and a resist pattern I5 is formed in the active region thereon by using a normal adhesive coating process.

In FIG. 2 [2], the area other than the active region of the single crystal substrate 11 is etched to a depth of approximately 1100 nm, that is, approximately the same depth as the epitaxial layer to be grown, to form a convex portion 12 in the active region on the substrate surface. .

In FIG. 2(3), an amorphous GaAs layer 13 of the same type as the growing molecules is grown over the entire surface of the substrate by sputtering, vapor deposition, or the like.

In FIG. 2 (4), the amorphous GaAs layer 1 in the active region
3A and amorphous GaAs in the field region.
Layer 13B is left as a selective mask for epitaxial growth.

In Figure 2 (5), GaA is used as a crystal layer on the entire surface of the substrate.
Grow the s-layer 14.

Then, a single crystal layer 1 is formed on the exposed single crystal substrate 11.
4A selectively grows epitaxially, forming amorphous GaA3
A crystal layer 14B on the layer 13 and the upper layer 3B grows.

In this case, the single crystal layer 14A grows on the single crystal exposed on the convex part 12, whereas the polycrystalline layer 14B grows on the single crystal exposed on the convex part 12.
It grows under the step formed by 2.

Therefore, single crystal 7i! 14A 0)? Polycrystalline layer 14[1 does not penetrate into region ii and narrow the area of single-crystalline layer 14A.

In addition, the polycrystalline N 14B becomes a high resistance layer and enables isolation between elements.

〔Effect of the invention〕

As explained in detail above, in the selective epitaxial growth according to the present invention, the polycrystalline layer in the field region is grown in the single-crystal layer region without penetrating into the single-crystal layer region that becomes the active region and narrowing the single-crystal layer region. The mismatched region at the interface with the active layer is formed outside the active layer, and no extra stress is generated at the interface.

Therefore, a growth method that is effective for miniaturization of element formation and isolation between elements can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view explaining the selective epitaxial growth of the present invention, FIG. 2 [1] to (5) are cross-sectional views explaining an embodiment of the selective epitaxial growth of the present invention, and FIG. 3 is a cross-sectional view explaining the conventional selective epitaxial growth. FIG. In the figure, 11 is a single crystal substrate, which is a 5R-GaAs substrate, 12 is a convex portion, 13B is a selection mask, which is an amorphous 1GaAs layer, 14 is a grown crystal layer, 14A is a single crystal layer, 14B is a polycrystalline layer, and 15 is a polycrystalline layer. It is a resist pattern. Kozo Iizuka Patent applicant Director of the Agency of Industrial Science and Technology

Claims (1)

[Scope of Claims] [1] A step of forming a convex portion (12) on a single crystal substrate (11), and forming an amorphous material in a region other than the convex portion (12) on the single crystal substrate (11). A selective epitaxial growth method comprising: depositing a layer (13B); and growing a crystal layer (14) all over the single crystal substrate (11). [2] The selective epitaxial growth method according to claim 1, wherein the amorphous layer (13B) is made of a substance having the same kind of molecules as the crystal layer (14) to be grown.