JP2508456B2 - Method for forming semiconductor single crystal thin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a semiconductor single crystal thin film for forming a compound semiconductor single crystal thin film separated by an insulating layer on a silicon semiconductor substrate.

[Outline of Invention]

The present invention is a method for forming a semiconductor single crystal thin film, in which a first insulating layer is selectively formed on a silicon semiconductor substrate,
The first epitaxial layer is formed by MOCVD, and the first insulating layer is formed on the silicon semiconductor substrate region where the first insulating layer is not formed and further laterally grown on the first insulating layer. After forming the compound semiconductor layer over the entire surface of the first insulating layer over the silicon semiconductor substrate region where the first insulating layer is not formed, the compound semiconductor layer formed over the silicon semiconductor substrate region where the first insulating layer is not formed is selected. And then a second insulating layer is formed on the surface of the silicon semiconductor substrate region from which the compound semiconductor layer has been removed,
Then, a second epitaxial growth is performed by MOCVD, and a compound semiconductor layer is formed on the second insulating layer by lateral growth using the compound semiconductor layer on the first insulating layer as a seed. This is so that a separated compound semiconductor layer crystal thin film can be formed.

[Conventional technology]

Ga (Al) As epitaxial growth on a silicon substrate includes a method using a GaAsP / GaP superlattice, a method using Ge as a buffer layer, and a method of growing GaAs directly by slow growth. On the other hand, on a GaAs substrate, SiO ₂ or SiN _X
In the case of selective growth of single-crystal GaAs through a mask of an insulating film such as, MBE (Molecular Beam Epitaxy) method deposits polycrystalline GaAs on the insulating film, MOMBE (Metal Organic Molecular Beam Epitaxy) method and low pressure MOCVD In the (metal organic chemical vapor deposition) method, nothing is deposited on the insulating film. It has also been reported that in the atmospheric pressure MOCVD method, particles are deposited on the insulating film unless the growth conditions are strict. Under a strict growth condition, lateral growth is somewhat performed on the insulating film, but lateral growth of a sufficient length cannot be obtained.

A method for growing a III-V group compound semiconductor single crystal thin film, for example, a Ga (Al) As single crystal thin film on an insulating film such as SiO ₂ or SiN _x has not been proposed yet.

[Problems to be solved by the invention]

By the way, for example, it is separated by an insulating layer on a silicon substrate.
If a III-V group compound semiconductor single crystal thin film can be formed, a composite device of a silicon-based element and a III-V group compound-semiconductor element can be obtained. Further, if a silicon single crystal thin film separated by an insulating layer can be formed on a silicon substrate, it can be applied to a three-dimensional device.

In view of the above points, the present invention provides a method for forming a semiconductor single crystal thin film capable of forming a compound semiconductor single crystal thin film separated by an insulating layer on a silicon semiconductor substrate.

[Means for solving problems]

According to the present invention, the first insulating layer (2) is selectively formed on the silicon semiconductor substrate (1), the first epitaxial growth is performed by the MOCVD method, and the first insulating layer (2) is not formed. It grows from the silicon semiconductor substrate region and further laterally grows on the first insulating layer to extend from the silicon semiconductor substrate region where the first insulating layer (2) is not formed to the first insulating layer (2). A compound semiconductor layer (3) is formed on the entire surface. Next, the compound semiconductor layer (3A) formed on the silicon semiconductor substrate region where the first insulating layer (2) is not formed is selectively removed, and the compound semiconductor layer (3A) is removed from the silicon semiconductor. A second insulating layer (2 ') is formed on the surface of the substrate area. After that, MOCVD again
Second epitaxial growth is performed by a method to form a compound semiconductor layer (3C) on the second insulating layer (2 ') by lateral growth using the compound semiconductor layer (3B) on the first insulating layer (2) as a seed. Form.

[Action]

In the first epitaxial growth step of forming the compound semiconductor layer (3) on the silicon semiconductor substrate (1) and the first insulating layer (2), in the silicon semiconductor substrate region where the first insulating layer (2) is not formed, The original single crystal compound semiconductor layer (3A) grows, lateral (lateral) growth occurs on the first insulating layer (2), and a single crystal compound semiconductor layer (3B) is similarly formed. Further, in the second epitaxial growth step of forming the compound semiconductor layer (3C) on the second insulating layer (2 ′), the single crystal compound semiconductor layer (3B) is used as a seed. Lateral growth again forms a single crystal compound semiconductor layer (3C). as a result,
A compound semiconductor single crystal thin film (4) separated by insulating layers (2) and (2 ') is formed on a silicon semiconductor substrate (1).

〔Example〕

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

Example 1 First, as shown in FIG. 1A, a SiO ₂ layer (2) is selectively formed on the surface of a group IV semiconductor such as a silicon substrate (1) by a selective oxidation (LOCOS) method.

Next, as shown in FIG. 1B, a group III-V compound semiconductor, for example, by a normal pressure MOCVD (metal organic chemical vapor deposition) method, is formed on the silicon substrate (1) on which the SiO ₂ layer (2) is selectively formed. The Ga (Al) As layer (3) is epitaxially grown. At this time, the Ga (Al) As layer (3A) is epitaxially grown on the silicon substrate (1) on which the SiO ₂ layer (2) is not formed. Further, lateral growth occurs and a single-crystal Ga (Al) As layer (3B) grows on the SiO ₂ layer (2).

Next, on the SiO ₂ layer (2) as shown in FIG. 1 C Ga (A
l) Other Ga (Al) As layer (3A) is selectively removed by etching, leaving only the As layer (3B). Next, selectively formed SiO ₂ layer (2 ') on a silicon substrate of any of the portion not covered with the SiO ₂ layer (2) as shown in FIG. 1 D (1). this
The SiO ₂ layer (2 ′) is formed, for example, by using an ordinary method and Ga
After covering the (Al) As layer (3B) with an oxidation resistant film, the whole is thermally oxidized.

After that, Ga (Al) As was epitaxially grown again by the above method, and the Ga (Al) As layer (3B) was used as a seed to perform lateral growth again to form a single crystal Ga (Al) As on the SiO ₂ layer (2 ′). Form the layer (3C). In this case, first the Ga (Al) As layer (3B)
The Ga (Al) As layer on the entire surface is somewhat uneven due to the formation of. Therefore, after this, the surface of the Ga (Al) As layer can be flattened. As a result, as shown in FIG. 1E, the SiO ₂ layers (2) and (2 ′) are formed on the silicon substrate (1), and the Ga (Al) As single crystal separated from the substrate (1) is formed thereon. A semiconductor substrate (6) having a thin film (4) formed thereon is obtained.

Embodiment 2 The embodiment of FIG. ₂ is different from that of FIG. 1 in the method of forming the SiO ₂ layer.

First, as shown in FIG. 2A, on the silicon substrate (1)
Later deposited SiO ₂ layer (2), etching away the SiO ₂ layer (2) in a predetermined pattern.

Next, as shown in FIG. 2B, a Ga (Al) As layer (3) is epitaxially grown on the silicon substrate (1) selectively formed on the SiO ₂ layer (2) by atmospheric pressure MOCVD, for example.

Next, as shown in FIG. 2C, the Ga (Al) As layer (3A) on the region where the SiO ₂ layer (2) is not formed is removed by selective etching. Next, as shown in FIG. 2D, SiO ₂ was redeposited and exposed by selective etching to remove the silicon substrate (1).
A SiO ₂ layer (2 ′) is deposited on top. At this time, Ga (A
l) It is conceivable that SiO ₂ is also deposited on the side surface of the As layer (3B). In this case, the SiO ₂ deposited on the side surface of the Ga (Al) As layer (3B) is removed by anisotropic etching such as ion milling or reactive ion etching.

Next, as shown in FIG. 2E, a Ga (Al) As layer is again epitaxially grown, and a single crystal Ga () is formed on the SiO ₂ layer (2 ′) by lateral growth using the Ga (Al) As layer (3B) as a seed. Al) As
Form the layer (3C). After that, the Ga (Al) As layer is flattened. As a result, a SiO ₂ layer (2) (2 ′) is formed on the silicon substrate (1), and a Ga (Al) As single crystal thin film (4) separated from the substrate (1) is formed on the semiconductor. A substrate (6) is obtained.

According to this method, a single crystal of Ga (Al) As can be grown on the SiO ₂ layer, and an arbitrary GaAs-based element can be formed on the silicon substrate. Then, an inexpensive silicon substrate having good quality and excellent heat resistance can be used, and the Si-based element and the GaAs-based element can be formed on the same substrate. As the GaAs element, a laser diode, a light emitting diode, a solar cell, a field effect transistor, a high mobility device (HEMT, TEGFET) using a two-dimensional electron gas channel, and the like can be considered.

The present invention can form a silicon semiconductor-insulating layer-compound semiconductor structure as in the above example.

Although SiO ₂ is used as the insulating layers (2) and (2 ′) in the above example, other insulating layers such as SiN _X can also be used. The same SiO ₂ was used for both insulating layers (2) and (2 ′),
Different insulating layers may be used.

〔The invention's effect〕

According to the present invention, a compound semiconductor single crystal thin film can be formed on an insulating layer on the surface of a silicon semiconductor substrate in a state of being insulated and separated from the silicon semiconductor substrate. So for example Si
Since it becomes possible to form a Ga (Al) As single crystal thin film on the substrate through an insulating layer, Ga (Al) As as an optical element or high-speed element can be formed.
By mixing As-based elements and Si-based elements, it becomes possible to apply to optoelectronic ICs and three-dimensional elements.

[Brief description of drawings]

1A to 1E and 2A to 2E are process diagrams showing an embodiment of a method for forming a semiconductor single crystal thin film according to the present invention. (1) is a silicon substrate, (2) and (2 ') are SiO ₂ layers,
(3) [(3A) (3B) (3C)] is a Ga (Al) As layer, (4)
Is a Ga (Al) As single crystal thin film.

Claims (1)

(57) [Claims] 1. A step of selectively forming a first insulating layer on a silicon semiconductor substrate; b. A silicon semiconductor in which the first epitaxial layer is formed by MOCVD and the first insulating layer is not formed. A compound semiconductor is grown on the substrate region and then laterally grown on the first insulating layer to cover the entire surface of the silicon semiconductor substrate region where the first insulating layer is not formed and the first insulating layer. A step of forming a layer, c. A step of selectively removing the compound semiconductor layer formed on the silicon semiconductor substrate region where the first insulating layer is not formed, and a step of removing the compound semiconductor layer. A step of forming a second insulating layer on the surface of the formed silicon semiconductor substrate region, and a second lateral growth using the compound semiconductor layer on the first insulating layer as a seed by performing the second epitaxial growth by the e.MOCVD method. The method for forming a semiconductor single crystal thin film and a step of forming the compound semiconductor layer on the second insulating layer.