JPS63164335A - Semiconductor substrate - Google Patents

Abstract

PURPOSE:To relax the warpage due to a difference between the thermal expansion coefficients of an Si substrate and GaAs semiconductor layers by burying recessed parts formed in the substrate with an insulator film consisting of Si. CONSTITUTION:Recessed parts 2 are formed in the desired regions of the main surface of an Si substrate 1. An Si oxide film 3 is deposited and the SiO2 film is remained in the recessed parts only by a normal method. Moreover, if necessary, nitrogen ions (N<+>) are implanted and an Si nitride (Si3N4) film 4 is formed. After that, GaAs semiconductor layers 5A and 5B, for example, are grown. The single crystalline GaAs semiconductor layer 5A is grown on the Si substrate and the polycrystalline GaAs semiconductor layer 5B is grown on the SiO2 films. After a substrate is formed, a device is formed on the semiconductor layer 5A. When the Si nitride film 4 is formed by an ion implantation method, the Si nitride film 4 is formed in contact as close as possible to the surface of the Si substrate 1 and also, holding the Si substrate surface in a single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor substrate, and more particularly, to a semiconductor substrate in which a silicon (Si) substrate and a gallium arsenide (Gab) based semiconductor layer are integrated.

Conventional technology Integrating Si semiconductor and GaAg semiconductor
GaAs-based semiconductor has high electron mobility and light emitting function,
On the other hand, for 81 semiconductors, large-diameter, high-quality crystals can be obtained, and device manufacturing technology has been established, so it is possible to fabricate highly integrated devices on Si substrates, high-speed devices on GaJu-based semiconductors,
It is promising as a composite device that integrates light-emitting devices and the like.

As a method for growing caAs on the S1 substrate, the MBIC method (Molecular Beam ICp) is used on the 81 substrate.
itax3r method) or B M OOV D method (Metal
Organic Chemical VaporDe
position) to deposit GaAs.
A device is formed at g. For example, using the MBE method on a p-type S1 substrate, an undoped GaAa layer, a carrier concentration of 10 cIn to form an active layer, an n-type GtAs layer with a thickness of 0.2 μm, and a carrier concentration of 101 to form an ohmic layer.
8 bacteria and a 0.4 μm thick nGaAs layer were sequentially formed.

Thereafter, a gate electrode, a source electrode, and a drain electrode are formed using conventional photolithography, recessing, and vacuum evaporation methods to form a field effect transistor (FIT). In this method, a large-diameter, inexpensive 81 substrate is used, and a thin layer of Gs 3 is deposited on the substrate, thereby reducing the cost of the GaAs substrate.

Problems to be Solved by the Invention In this conventional example, the GILA8 semiconductor layer is formed directly on the r4, Si substrate, but as the diameter of the 81 substrate increases, due to the difference in thermal expansion coefficient between the 81 substrate and the GILAS layer. , soshi occurs. For example, when a 2 μm thick GaAs layer is formed on an 81 substrate having a diameter of 2 inches, a warpage of about 20 μm occurs, causing problems such as the inability to perform fine processing and the substrate breaking during the process. Also, integrated circuits etc.
When formed in an aAs semiconductor layer, a problem arises in that current flows through the silicon substrate, so-called isolation between elements is insufficient.

The present invention relates to a semiconductor substrate in which a GiLAg-based semiconductor layer is formed on a D-81 substrate, and provides a semiconductor substrate with a large diameter, no rips, and isolation between elements.

Means for Solving Problems The present invention [forming a recess in a desired region of a Si substrate, filling the recess with an insulator made of Sl, and then implanting an ion implantation species between the recesses to make the silicon an insulator After connecting the recesses with an insulator, GILA is placed on the 81 substrate.
The present invention relates to a semiconductor substrate consisting of all semiconductor layers.

By filling the recesses formed in the active Si substrate with an insulator made of 81, the distortion caused by the difference in thermal expansion coefficient between the 81 substrate and the G&M S-based semiconductor layer can be alleviated by the insulator filled in the recesses. By connecting the recesses with an insulator formed by ion implantation, GILA! ! Elements formed in a semiconductor layer can be electrically isolated.

Example An embodiment of the present invention will be described in detail below.

1 to 4 show the manufacturing process of a semiconductor substrate according to an embodiment of the present invention.

81 A recess 2 is formed in a desired region of the main surface of the substrate 1 using an erosion method (FIG. 1). OV D (Chemical
A silicon oxide film (Si02) 3 is deposited using a vapor deposition method, and 5102 is left only in the recessed portions using a conventional method (FIG. 2). Using the ion implantation method, nitrogen ions (N) are implanted as the implantation species.
60Kev Terror X1d6Ci2 ion implantation, 950'
Heat treated with C for 3 hours to form silicon nitride (5i5N4)
4 (Figure 3). After that, M B R (Mo
leularBeam I! G & M S semiconductor layer 6 M using the pi, taxi) method.

Grow 6B. Single crystal GILA is on the 81 substrate! 1
A semiconductor layer of 6 μm is grown, and a polycrystalline GIL is grown on 8i02.
A! An i-semiconductor layer 6B grows (FIG. 4). After forming the substrate shown in FIG. 4, devices are formed on the single crystal GtAJ semiconductor layer 6. What is important in Fig. 3 is that when silicon nitride 4 is formed by ion implantation, the silicon nitride 4 is in contact with the surface of silicon substrate 1 as much as possible, and the silicon substrate surface is kept in a single crystal state. It is to be.

In the example, GILAS semiconductor layer 6 was formed, but M1
1-2GazAs, In1--ILzAS, etc. or a multilayer structure thereof may be formed. Although the MBE method was used as the method for growing the Ga-S semiconductor layer, it goes without saying that the MOCVD method may also be used.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention involves forming a recess in a Si substrate and filling the recess with an insulator made of silicon. With an insulator made of silicon, a Si substrate and a GI
The damage caused by the difference in thermal expansion coefficients of the LAII-based semiconductor layers is alleviated. Furthermore, since the silicon insulator is formed near the silicon surface between the recesses in which the silicon insulator is embedded, it is possible to electrically isolate devices formed in the GaAg-based semiconductor layer.

[Brief explanation of the drawing]

1 to 4 are process diagrams for explaining a semiconductor substrate according to an embodiment of the present invention. 1...81 Substrate, 2... Concavity, 3.
...Silicon oxide, 4...Silicon nitride, 6M...Single crystal GajLi semiconductor layer,
6B...Polycrystalline GaAs semiconductor layer.

Claims (2)

[Claims] (1) A recess is provided in the silicon substrate, the recess is filled with an insulator made of silicon, and a GaAs layer is placed on the silicon substrate.
A semiconductor substrate formed by forming a semiconductor layer. (2) An implantation species that turns the silicon substrate into an insulator is ion-implanted between the recesses filled with an insulator made of silicon, and the plurality of recesses are connected by the insulator. The semiconductor substrate according to item 1.