JPH0449627A - Manufacture of compound semiconductor device - Google Patents

Abstract

PURPOSE:To enable back-crate effect and side-crate effect to be reduced by forming an insulation layer below an operation layer. CONSTITUTION:Boron is implanted into an entire surface of a semiinsulation compound substrate 1 by the ion-implantation method for forming an insulation layer 6. After that, silicon is implanted selectively, heat treatment is performed, and an operation amount (n) 4 is formed. Crystal defect which is generated when forming the insulation layer 6 can be recovered to some extent but crystal defect remains in a region of the insulation layer 6 which is 0.3mum to 0.5mum deep from a surface of the semi-insulation compound substrate 1, and this presence restricts back gate effect. Then, a Schottky gate electrode 1, a source electrode 2, and a drain electrode 3 are formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a compound semiconductor device.

[Conventional technology]

Conventionally, this type of compound semiconductor device, especially a field effect transistor (FET), has a structure as shown in the cross-sectional schematic diagram in FIG.
Operating layer (n layer) formed on the surface of the semi-insulating compound substrate 1
4, a Schottky gate electrode 1, and an ohmic source electrode 2. and a drain electrode 3. In recent years, integrated circuits using such FETs have been put into practical use and commercialized.

[Problem to be solved by the invention]

In the case of the FET mentioned above, the so-called back gate effect becomes a problem, and when a potential as shown in FIG. 2 is applied between this FET and the side gate electrode 7 of the adjacent FET, the back gate effect It will rain as an effect. This is a phenomenon in which characteristic fluctuations of adjacent FETs, particularly drain currents, decrease due to voltage application to the side gate electrode 7.

In this case, the back gate effect, which occurs due to fluctuations in the potential of the semi-insulating compound substrate 1 under the active layer (n layer) 4, causes the integrated circuit to operate abnormally. This is an obstacle to increasing the degree of integration.

[Means to solve the problem]

The method for manufacturing a compound semiconductor device of the present invention involves implanting ions, for example, boron, protons, or oxygen, into the surface of a semi-insulating compound substrate at a position deeper than the active layer formation region, for example, from 0.3 μm to 0.3 μm. 5μ
The method includes the steps of forming an insulating layer to a depth of m, forming an active layer on the insulating layer, and forming a compound semiconductor device.

〔Example〕

FIGS. 1(a) and 1(b) are sectional views for explaining one embodiment of the present invention.

First, as shown in FIG. 1(a), boron was injected at 150 keV onto the entire surface of a semi-insulating compound substrate 1 by ion implantation.
The insulating layer 6 is formed by implanting under the condition of I x 1013 cm-''.

Thereafter, as shown in FIG. 1(b), silicon is selectively implanted and heat treated at about 800°C to form an active layer (n
) form 4. Through this heat treatment, crystal defects that occurred during the previous formation of the insulating layer 6 are recovered to some extent, but the temperature is 0.3 μm to 0.5 μm from the surface of the semi-insulating compound substrate 1.
Crystal defects remain in the region of the insulating layer 6 with a depth of m, and the presence of these defects can suppress the back gate effect.

Next, Schottky gate electrode 1. Source electrode 2. By forming the drain electrode 3, the manufacture of the FET is completed.

In this embodiment, boron was used for ion implantation to form the insulating layer 6, but proton or oxygen ion implantation may also be used.

Note that in this example, the insulating layer 6 was formed before forming the active layer 4. Conversely, if the insulating layer 6 is formed after the active layer 4 is formed, no heat treatment is performed after the formation of the insulating layer 6, so that the back gate effect is greatly suppressed. However, many crystal defects are formed in the active layer 4, and the FET characteristics 1
For example, this results in a decrease in mutual conductance.

〔Effect of the invention〕

As explained above, the present invention eliminates the back gate effect by forming an insulating layer under the active layer.

Side gate effects can be reduced.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional views for explaining an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view for explaining a conventional technique. DESCRIPTION OF SYMBOLS 1... Schottky gate electrode, 2... Source electrode, 3... Drain electrode, 4... Operating layer, 5... Semi-insulating compound substrate, 6... Insulating layer, 7...・Side gate electrode.

Claims (1)

[Claims] 1. An insulating layer is formed on the surface of a semi-insulating compound substrate at a position deeper than an active layer formation region by ion implantation, an active layer is formed on the insulating layer, and a compound semiconductor device is formed. A method for manufacturing a compound semiconductor device, characterized in that: 2. The method of manufacturing a compound semiconductor device according to claim 1, wherein the ion implantation method is a method of implanting boron, protons, or oxygen ions.