JPH07161733A - Manufacture of compound semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the method of forming an insulating film which is not affected by hydrogen passivation of a P-type semiconductor layer, regarding the manufacturing method of an insulating film which is used in a semiconductor device. CONSTITUTION:In the method of manufacturing a semiconductor device wherein a P-type compound semiconductor turns to a part of an operating layer, a first insulating film 2 in contact with the surface of a P-type semiconductor 1 is stuck by a forming method which does not use plasma. A second insulating film 3 is subsequently formed on the first insulating film 2 by laminating, or the formation of the insulating film in contact with the surface of the P-type semiconductor 1 is started at 350 deg.C or higher in a plasma atmosphere containing hydrogen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an insulating film used in a semiconductor device. In recent years, with the development of portable information communication systems, high-density information transmission has become important, and the demand for microwave communication devices in the microwave region is increasing.

In order to construct such a device, a conventional semiconductor device based on silicon is insufficient in frequency characteristics, and a device using a compound semiconductor such as GaAs which enables higher speed operation is required. Is becoming.

[0003]

2. Description of the Related Art Transistors using compound semiconductors are
At present, it is a field-effect transistor whose channel is generally an n-type, and the circuit is composed of so-called enhancement type and depletion type elements.

However, in a circuit having such a structure, normally,
Since a current flows not only during operation but also during standby and consumes power, there arises a problem that an important battery life is shortened in a portable device. In order to overcome such drawbacks, in compound semiconductor field effect transistors, a p-type channel device like a silicon device was developed,
It is important to configure complementary circuits to reduce standby current consumption.

Also in the compound semiconductor, a manufacturing process of an element having n-type conductivity has been conventionally established, and p
The fabrication process is believed to be compatible because the only structural differences between the type and n-type elements are the differences in the conductivity of the layers that are essential to their operation.

[0006]

However, in the compound semiconductor, in the p-type semiconductor layer, hydrogen atmosphere during growth or process, for example, hydrogen in silane plasma for forming an insulating film is taken into the layer. The effect of so-called hydrogen passivation, which is associated with the acceptor and inactivates the acceptor, is more significantly affected than that of the n-type semiconductor layer, and the element characteristics are significantly deteriorated after the insulating film forming process during the process.

Further, the acceptor inactivated by the hydrogen passivation can be reactivated by a heat treatment called so-called annealing. Usually, the temperature required for it is 500 to 600 ° C., and the crystal growth temperature of the layer. This causes problems such as impairing the steepness of the interface.

An object of the present invention is to obtain a method for forming an insulating film which is not affected by hydrogen passivation of a p-type semiconductor layer.

[0009]

FIG. 1 is a diagram illustrating the principle of the present invention, and FIG. 2 is a diagram showing the relationship between the p-type GaAs substrate temperature and carrier concentration in hydrogen plasma, and the amount of hydrogen taken in.

In the figure, 1 is a p-type semiconductor and 2 is a first
Insulating film 3, 3 is a second insulating film, and 4 is plasma containing hydrogen. Therefore, as a first method, the inventor formed the first insulating film 2 that is in direct contact with the surface of the semiconductor 1 of the compound semiconductor device by a method not using plasma, and then used the plasma 4 containing hydrogen. The second insulating film 3 is formed by the film forming method, or the second method is to raise the temperature during film formation (so-called simultaneous annealing).
As a result, a method of reducing hydrogen intrusion into the insulating film which is in direct contact with the surface of the semiconductor 1 and the like has been invented.

That is, an object of the present invention is a method of manufacturing a semiconductor device in which a p-type compound semiconductor is at least a part of an operation layer as shown in FIG. The first insulating film 2 in contact with the surface of the semiconductor 1 shown in the figure is deposited by a forming method that does not use plasma, and then the second insulating film 3 shown in FIG. This is achieved by stacking the first insulating film 2 on the first insulating film 2 or by starting the formation of the insulating film in contact with the surface of the semiconductor 1 at a temperature of 350 ° C. or higher in the atmosphere of the plasma 4 containing hydrogen. It

[0012]

As shown in FIG. 1, it is an explanatory view for preventing hydrogen from penetrating into a semiconductor by forming an insulating film which is in direct contact with the semiconductor surface by a method which does not use plasma.

In the figure, the first insulating film 2 is an insulating film that is in direct contact with the semiconductor, and is formed by a deposition method that does not use plasma containing hydrogen, for example, a vacuum evaporation method. The second insulating film 3 is an insulating film formed by a deposition method including a plasma chemical vapor deposition method using a gas containing hydrogen after forming the first insulating film 2.

When such an insulating film deposition method or insulating film structure is used, the semiconductor surface is not exposed to a large amount of hydrogen during the deposition of the first insulating film 2, and hydrogen invades into the semiconductor. Is suppressed and the type of insulating film is limited by the deposition method (for example, oxynitride film (SiO 2
(N) is difficult to form by a vacuum vapor deposition method), the first insulating film 2 has a minimum film thickness for preventing the invasion of hydrogen, and then the second insulating film 3 is formed. Therefore, the degree of freedom in the device manufacturing process is not impaired.

FIG. 2 shows p-type GaA in hydrogen plasma.
s shows the relationship between the substrate temperature, the amount of hydrogen taken in, and the carrier concentration. (Watanabe et al., J.Appl.Phys
Vol.73, p8146 (1993) According to this, when the substrate temperature is around 250 ° C, the hydrogen uptake amount and the carrier concentration decrease maximally, and as the substrate temperature rises, the hydrogen uptake amount and the carrier concentration decrease less, and 350 ° C Above, there is almost no change in carrier concentration. Therefore, by setting the substrate temperature to 350 ° C. or higher when forming the insulating film using plasma,
It is possible to prevent hydrogen from penetrating into the sample. Further, since element deterioration can be prevented at a temperature lower than the temperature (500 to 600 ° C.) required for reactivating the acceptor by annealing after film formation, there is no fear of degrading crystal quality such as interface sharpness. .

[0016]

FIG. 3 is a schematic sectional view in order of steps of a first embodiment of the present invention, and FIG. 4 is a schematic sectional view in order of steps of a second embodiment of the present invention.

In the figure, 5 is a semi-insulating GaAs substrate,
Reference numeral 6 is a HEMT constituent layer, 7 is a SiO ₂ film, 8 is a SiON film, 9 is a gate electrode, 10 is a source electrode, and 11 is a drain electrode. First, a first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 3A, semi-insulating GaA
On the substrate 5, a buffer layer, a channel layer, a hole supply layer,
As a cap layer, etc., GaAs, AlGaAs layers, etc. are alternately laminated and grown by an epitaxial method, and HEMT
The constituent layer 6 is obtained.

Next, as shown in FIG. 3B, a thin silicon dioxide (SiO ₂ ) film of about 1000 Å is grown on the p-type GaAs layer by a growth method without using plasma. Subsequently, as shown in FIG. 3C, a silicon oxynitride (SiON) film 8 is formed by a plasma chemical vapor deposition method using a mixed gas of silane, ammonia and laughing gas (SiH ₄ / NH ₃ / N ₂ O). 3,000 Å
Deposited at a film thickness of.

After that, the SiO ₂ film 7 and the Si are
An opening is formed in the insulating film in which the ON film 8 is laminated, and HEMT
The gate region of the constituent layer 6 is etched to form a cap layer, and the gate electrode 9 having a recess structure is formed on the cap layer. At the same time, the source electrode 10 and the drain electrode 11 are formed on the HEMT constituent layer 6
Is formed on the cap layer to complete the HEMT.

Next, a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 4A, semi-insulating G
As a buffer layer, a channel layer, a hole supply layer, a cap layer, etc., GaAs, AlGaAs layers, etc. are alternately laminated and grown on the aAs substrate 5 by an epitaxial method.
The MT constituent layer 6 is obtained.

Next, as shown in FIG.
The substrate temperature is set to, for example, 400 by the plasma chemical vapor deposition method using a mixed gas of ammonia and laughing gas (SiH ₄ / NH ₃ / N ₂ O).
A SiON film 8 having a film thickness of 3,000 Å is deposited on the HEMT constituent layer 6 under the condition of ° C.

After that, an opening is formed in the SiON film 8 by a well-known technique, the gate region of the HEMT constituting layer 6 is etched to form a cap layer, and a gate electrode 9 having a recess structure is formed thereon. At the same time, the source electrode 10 and the drain electrode 11 are formed on the cap layer of the HEMT constituting layer 6 and HE
Complete MT.

[0024]

As described above, according to the present invention,
P does not deteriorate element characteristics due to hydrogen passivation
Has the effect of obtaining a compound semiconductor having a positive active layer,
It greatly contributes to the production of compound semiconductor devices such as compound semiconductor integrated circuits.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 shows the relationship between the p-type GaAs substrate temperature and carrier concentration in hydrogen plasma, and the amount of hydrogen taken up.

3A to 3C are schematic cross-sectional views in order of the processes of the first embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view in order of the steps of a second embodiment of the present invention.

[Explanation of symbols]

1 p-type semiconductor 2 first insulating film 3 second insulating film 3'insulating film 4 plasma containing hydrogen 5 semi-insulating GaAs substrate 6 HEMT constituent layer 7 SiO ₂ film 8 SiON film 9 gate electrode 10 source electrode 11 Drain electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/203 Z 8719-4M 21/316 X 7352-4M 29/778

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device in which a p-type compound semiconductor is at least a part of an operating layer, wherein a first insulating film (2) in contact with a surface of a semiconductor (1) is formed without using plasma. Method and then a second insulating film
A method for manufacturing a compound semiconductor device, comprising: forming (3) on the first insulating film (2). 2. A method for manufacturing a semiconductor device in which a p-type compound semiconductor is at least a part of an operation layer, wherein a plasma (4) containing hydrogen in an insulating film (3 ′) in contact with the surface of a semiconductor (1). In the atmosphere, the formation is started at a temperature of 350 ° C. or higher, and the method for manufacturing a compound semiconductor device.