JPH0358483A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device excellent in interfacial characteristic and high in breakdown strength by a method wherein a first AlxGa1-xAs layer is provided onto a compound semiconductor operating layer which contains In, which is thermally treated at a temperature of 650-800 deg.C, and a second AlxGa1-xAs layer is provided thereon. CONSTITUTION:A compound semiconductor operating layer 2 which contains In and a contact layer 3 are formed on a semi-insulating InP substrate 1. In this case, a first AlxGa1-xAs layer 4 is formed on the In-containing compound semiconductor operating layer 2, which is thermally treated at a temperature of 650-800 deg.C, and a second AlxGa1-xAs layer 6 is provided thereon. A source electrode 7 and a drain electrode 9 are formed, and furthermore a gate electrode 8 is built. That is, a thin AlGaAs is provided onto an In-containing compound semiconductor operating layer, which is thermally treated to form an interface level lessened layer, and then an AlGaAs is provided again, whereby an insulating film can be formed without making impurity diffuse into the whole insulating film or increase in the through transition. By this setup, a semiconductor device excellent in interfacial characteristic and high in breakdown strength can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device having an active layer made of a compound semiconductor containing In, and particularly to a method for manufacturing a semiconductor device having good interface characteristics.

[Conventional technology]

Metal-insulator-semiconductor (MIS) whose active layer is a compound semiconductor containing In? li field effect transistor (FET)
For example, the International Electron Device Meeting (International E
(Lekutoran Device Meeting)
In 1986-P77t, there is an example in which rnP is used as an operating layer, as announced by Itoh et al. Conventionally, an active layer 2 and a contact layer 3 are formed by ion implantation and annealing on a semi-insulating InP substrate 1 as shown in FIG. 20, or by VPE method, etc. as shown in FIG. 2(b). ,
Next, as shown in FIG. 2(b), after growing an A (lGaAs layer) as a gate insulating film 6 by the MBE method, a second
A field effect transistor has been realized by forming a gate electrode 8, a source electrode 7, and a drain electrode 9 as shown in FIG.

[Problems to be solved by the invention] However, MISFETs manufactured using conventional manufacturing methods
For example, with InP as the active layer and AI2GaAs as the active layer,
In MISFETs with a structure in which the layer is a gate insulating film, interface states still exist at the interface after growth, although they have been reduced, and this causes problems such as frequency dispersion and hysteresis in the storage region in the capacitance voltage characteristics. A problem has arisen. In addition, it has an adverse effect on the FET characteristics in dableation mode, such as an increase in transconductance and difficulty in enhancement operation.
There was a significant effect on high frequency characteristics in large amplitude operation. It was found that these phenomena could be improved by heat treatment after growth, but on the other hand, a phenomenon was observed in which the gate breakdown voltage deteriorated due to heat treatment.

The present invention relates to a method for manufacturing a semiconductor using a compound semiconductor containing In as an active layer, and particularly to a method for manufacturing a semiconductor device having good interface characteristics.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device in which a compound semiconductor containing In is used as an active layer, and an ARxGa, -xAs layer (0≦x≦1) is provided on the active layer of the compound semiconductor containing In. After providing a first AI2xGa, -xAs layer on the In-containing compound semiconductor operating layer, heat treatment is performed at 650 to 800°C, and a second lxG
a, an As layer is provided.

[Effect]

When manufacturing an FET using a compound semiconductor containing In as an active layer, it is necessary to form an appropriate insulating film because the compound semiconductor containing In has a low Schottky barrier height.

It has been found that AQGaAs, which is the same compound semiconductor as the active layer, is useful as this insulating film, although it has a lattice mismatch. However, even in a structure in which an insulating film of AI20aAs is grown on the active layer, crystal defects occur at the interface due to lattice misalignment and form interface states, or interface states are formed due to residual impurities.

These interface states have been a cause of deterioration in the characteristics of semiconductor devices. However, it has been found that these interface states are reduced by heat treatment and the interface properties are improved. On the other hand, there is a phenomenon in which the gate breakdown voltage deteriorates due to heat treatment, and it is necessary to achieve both good interface characteristics and high gate breakdown voltage. Therefore, if a thin AQGaAs layer is provided on a compound semiconductor active layer containing In, this is heat-treated to form an interface state reduction layer, and then lGaAs is provided again, this will prevent impurities from diffusing throughout the insulating film. Since an insulating film can be formed without increasing threading dislocation, a gate insulating film with good interface characteristics and high breakdown voltage can be obtained. Furthermore, using this manufacturing method means that A2
When growing GaAs, it is possible to grow thin AQGaAs, heat-treat it in an As atmosphere, and continue growing, so there is no need to apply a protective film for heat treatment or take it outside to re-grow it. becomes.

[Example] An embodiment of the present invention will be described below with reference to FIG.

An n- 1nP active layer and n+- as contact layer 3
An InP contact layer is formed. Then, as shown in FIG. 1(Q), ARGaAs
Layer 4 is AQ, , Ga, , xAs at a substrate temperature of 500
Grows by 300 people at ℃. During growth, In
Clean the P surface and immediately perform the precept. Thereafter, the temperature was raised to 750° C. and held for 10 minutes while continuously irradiating As molecules. By carrying out the MBE process under As irradiation in an MBE chamber, surface deterioration can be prevented without the need for a surface protective film, and defects generated at the interface due to the heat treatment can be alleviated, thereby reducing the interface state.

In Figure 1 ■, 5 is heat-treated AffiGaA
The s-layer is shown. Furthermore, after this, the substrate temperature was increased to 600℃.
Lower it to AQ. ．． , Ga. , xAs to a thickness of 400 A and forming an lGaAs layer 6 as shown in FIG. 1(e), a gate insulating film having a high breakdown voltage can be obtained.

Using the obtained crystal, the ohmic part was opened using the usual method, and the lrl! As shown in U (a), the source electrode 7 and the drain electrode 9 are formed, and the gate electrode 8 is formed.
to obtain a field effect transistor.

In the above embodiments, the active layer was InP, but AI2GaAs was used as the active layer.
It is possible to use a semiconductor layer containing In such as a semiconductor layer.

Further, although the composition ratio of AffiGaAs was set to X=0.3, it is not limited to this. Furthermore, the film thickness is not limited to this.

Figure 3 shows F with the conventional manufacturing method and structure without heat treatment.
The capacitance voltage characteristics between the source and gate of ET are shown. As shown in the figure, without heat treatment, frequency dispersion is observed in the accumulation region, and transconductance gm is also observed to be overcrowded. Further, FIG. 4 shows the current-voltage characteristics between the source and gate of the FET in a structure that has been heat-treated after growth. Although the capacitance voltage characteristics are improved, there is a decrease in reverse breakdown voltage. On the other hand, in the FET manufactured by the manufacturing method and structure of the present invention, as shown in FIG. 5, the capacitance-voltage characteristics are good and interface states can be reduced, and as shown in FIG. 6, the reverse breakdown voltage is reduced. I can't even see it.

[Effects of the Invention] As described above, according to the present invention, a semiconductor device having an active layer made of a compound semiconductor containing In, which has good interface characteristics and insulation properties, can be obtained, and can be used as a high-speed high-frequency integrated circuit or a high-frequency, high-output device for communication or logic. Its contribution to circuits and other fields is significant.

[Brief explanation of drawings]

1(a) to ω are structural cross-sectional views of a semiconductor device for explaining the manufacturing method of the present invention, and FIGS. 2(a) to ω are structural cross-sectional views of a semiconductor device for explaining the conventional manufacturing method. Figure 3 is a diagram showing the capacitance voltage characteristics between the gate and source electrodes of a semiconductor device manufactured by the conventional manufacturing method without heat treatment.
The figure shows the gate and
Source 1!A diagram showing current-voltage characteristics between one pole, FIG. 5 is a diagram showing capacitance-voltage characteristics of a semiconductor device using the manufacturing method according to the present invention, and FIG. 6 is a diagram showing a semiconductor device using the manufacturing method according to the present invention. FIG. 2 is a diagram showing the current-voltage characteristics of l...Semi-insulating substrate

Claims (1)

[Claims] (1) A compound semiconductor containing In is used as an active layer, and AlxGa_1_-_xAs is formed on the compound semiconductor containing In.
In the method for manufacturing a semiconductor device in which a layer (0≦x≦1) is provided, a first A layer is formed on the compound semiconductor operating layer containing In.
After providing lxGa_1_-_xAs layer, 650-80
After heat treatment at 0°C, a second AlxGa_1_-_x
A method for manufacturing a semiconductor device, comprising providing an As layer.