JPH01290230A - Annealing method - Google Patents

Abstract

PURPOSE:To enable the elimination of a donor defect in a bulk without inducing a defect to occur in a crystal surface by a method wherein the surface of a III-V compound semiconductor crystal such as GaAs or the like is subjected to a hydrogen annealing in such a manner that the crystal surface is protected against the ion bombardment by using only hydrogen radicals. CONSTITUTION:A III-V semiconductor compound such as GaAs, InP, GaP, and the like is employed as an applicable compound, and a device composed of a plasma generating chamber 1 connected with a GaAs substrate (water) treating chamber 2 is used. First, H2 gas is supplied to the inside of a depressurized plasma treating chamber 1 to generate hydrogen plasma 3, and the hydrogen radicals are supplied to a wafer treating chamber 2. A untreated GaAs substrate 6 is placed on a quartz stage 5 inside the wafer treating chamber 2, whose surface is exposed to an H2 gas flow which contains a large amount of hydrogen radicals to neutralize donors so as to terminate the defect. by these processes, a donor defect in a bulk can be terminated without inducing defects to occur in the surface of a III-V compound semiconductor.

Description

Detailed Description of the Invention [Summary] This invention relates to a method of annealing m-v group compound semiconductor crystals such as GaAs, and particularly relates to an H2 plasma treatment method for erasing dangling bonds in GaAs crystals. The purpose of this is to eliminate donors and defects in the bulk without inducing defects on the GaAs crystal surface during crystal annealing. The surface of the m-v group compound semiconductor substrate is further exposed to a plasma containing hydrogen whose ion energy has a maximum value of 50 eV or less.

[Industrial application field]

The present invention relates to a method of annealing an m-v group compound semiconductor crystal such as GaAs, and more particularly to an H2 plasma treatment method for eliminating dangling bonds in a GaAs crystal.

[Conventional technology]

Compound semiconductor integrated circuits are FE on semi-insulating GaAs substrates.
It has evolved from T technology.

GaAs, which is a 111-V group compound semiconductor, originally contains trace amounts of elements such as Si, Ge, or S, and these elements eliminate dangling bonds caused by defects such as shallow donor levels and dislocations. To achieve this, H2 plasma treatment is performed to combine dangling bonds with hydrogen atoms, reduce carrier concentration, and improve the reverse breakdown voltage of the Schottky junction.

[Problem to be solved by the invention]

Conventionally, when performing the above H2 plasma treatment, a parallel plate electrode type plasma generator is used, and the GaAs single crystal substrate is placed between parallel plate electrodes and directly exposed to plasma, so that donors and defects in the bulk are eliminated. Many new defects are induced on the GaAs surface that is embedded (terminated) by hydrogen atoms but hammered by H2 plasma, and the height of the Schottky barrier decreases (Φ, =
0.67-0.52eV).

An object of the present invention is to eliminate donors and defects in the bulk without inducing defects on the surface of the GaAs crystal during annealing of the GaAs crystal using H2 plasma.

[Means to solve the problem]

According to the present invention, the above-mentioned problems are solved by an annealing method characterized by exposing the surface of an m-v group compound semiconductor substrate to a gas flow containing only hydrogen radicals without containing hydrogen ions;
The problem is solved by an annealing method characterized by exposing the surface of the -v group compound semiconductor substrate to plasma containing hydrogen whose ion energy has a maximum value of 50 eV or less.

[For production]

According to the first method of the present invention, when hydrogen annealing the surface of a crystal of a compound semiconductor of the 1-2 group such as GaAs, the crystal surface is hydrogen-annealed using only hydrogen radicals so that the surface of the crystal is not bombarded with ions.

Furthermore, according to the second method of the present invention, the energy of the hydrogen plasma ions themselves is suppressed to a small value of 50 eV or less, so it is possible to suppress the induction of defects due to ion bombardment. When it exceeds 50 eV, ion bombardment is applied and defects are induced.

GaAs is an m-v group bioconductor compound that can be applied to the present application.
, InP, GaP〒χ≧1000, etc. These compounds were prepared on Ge, 5il-8 substrate, SOS (
SiliconOn 5aphire) or S
OI (Silicon OnInsmlator)
) is also used above.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

As shown in FIG. 1, first, an apparatus is used in which a plasma generation chamber 1 and a GaAs substrate (wafer) processing chamber 2 are communicated with each other.

First, a plasma processing chamber 1 under reduced pressure of 0.1 to 3 Torr.
11□ gas is supplied into the chamber at a rate of 100 cc/min, and hydrogen plasma 3 is generated by setting the RF frequency to about 13.56 MIIz. In addition, H! An inert gas such as Ar may be supplied together with the gas. A shield plate 4 is installed inside the plasma processing chamber 1.
is provided to supply plasma-excited hydrogen radicals to the wafer processing chamber 2. In the wafer processing chamber 2, a GaAs substrate 6 to be processed is placed on a quartz stage 5.
2 gas flow to neutralize the donor and terminate the defect.

In order to increase the annealing effect, the GaAs substrate may be heated to a temperature of 350° C. or lower. If the temperature exceeds 350℃, GaAs
This becomes a problem due to the detachment of As atoms from the crystal.

FIGS. 2 and 3 show modified examples of the plasma generation chamber of the above embodiment, and show an example using a high frequency coil 7 and an example using a microwave 8, respectively. In either case, hydrogen radicals can be supplied to the wafer processing chamber similarly to the above embodiments.

FIG. 4 is a schematic diagram showing an example of plasma generation using an ECR plasma generator.

ECR (Electron Cyclotron Resonance) plasma generation is a well-known method in which microwaves 8 are applied to a reduced pressure magnetic field of 10-5 to 10-'' Torr to turn H2 gas supplied at 10 cc/min into plasma, which is directly exposed onto the GaAs substrate 6. In this case, Ga
Does not damage the As surface. 9 is magnet.

Figures 5 and 6 show Ti/Pt/A on an n-type GaAs substrate.
2 is a graph showing a comparison between the present invention and a conventional example of the relationship between hydrogen annealing time, reverse breakdown voltage, and barrier height in a device in which a u-electrode is formed. It can be seen that in any case, the present invention is better than the conventional example.

〔Effect of the invention〕

As explained above, according to the present invention, donor defects in the bulk can be eliminated without inducing defects on the surface of the m-v group compound semiconductor.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are modifications of the plasma generation chamber of the above embodiment, and are an example using a high frequency coil 7 and a microwave 8
FIG. 4 is a schematic diagram showing an example of plasma generation using an ECR plasma generator, and FIGS. 5 and 6 are examples of plasma generation using an ECR plasma generator.
It is a graph showing the relationship between hydrogen annealing time, reverse breakdown voltage, and barrier height in a device in which a Pt-/Au electrode is formed, comparing the present invention and a conventional example. l... plasma processing chamber, 2... wafer processing chamber, 3
...Hydrogen plasma, 4...Shield plate, 5...
・Quartz stage, 6...G a As 4
j&, 7...High frequency coil, 8...Microwave.

Claims (1)

[Claims] 1. An annealing method characterized by exposing the surface of a III-V group compound semiconductor substrate to a gas flow containing only hydrogen radicals and no hydrogen ions. 2. An annealing method characterized by exposing the surface of a III-V compound semiconductor substrate to plasma containing hydrogen whose maximum energy value of ions is 50 eV or less.