JPS62167290A - Vapor growth method for iii-v compound semiconductor - Google Patents

Abstract

PURPOSE:To make dependency of doping amount for the temp. of a base plate small by using the combination of both a group of SiH4, GeH4 and a group of H2S, H2Se as a raw material for doping in vapor growth of organic metal. CONSTITUTION:In vapor growth of GaAs of the like wherein organic metal such as trimethylgallium and arsine is used as a raw material, both at least one of SiH4, GeH4 and at least one of H2S, H2Se are combined and simultaneously used as a raw material for doping. The dependent temp. of a base plate can freely be controlled by this method and the dependency of doping amount for the temp. of the base plate can almost be eliminated. also even if temp. ununiformity is present in the inside of the base plate, the high-uniform distribution of doping amount can be obtained in the inside of the base plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for vapor phase growth of IV group compound semiconductors, particularly n
This relates to controlling the doping amount of type impurities.

[Conventional technology]

In the vapor phase growth of a ■-■ group compound semiconductor, control of the doping amount and uniformity of the doping amount within the substrate are the most fundamental and important points. Conventionally, metal-organic vapor phase epitaxy (
When doping with n-type impurities by MOCVD method, silicon (Si) and germanium (Ge), which are group II, are used.
Alternatively, one element is selected and used from group Ⅰ such as sulfur (S) and selenium (Se). The raw material gases are silane (SiH4) and germane (GeHl), respectively.
), hydrogen sulfide (H,S), hydrogen selenide (H2Se)
and other hydrides.

[Problem that the invention seeks to solve]

It is known that in the MOCVD method of group (1)-(2) compound semiconductors, the growth rate is approximately constant over a wide substrate temperature range. Therefore, the growth rate can be easily controlled, and even if the temperature is non-uniform within the substrate, the uniformity of the thickness of the grown layer remains at a good value. However, since the doping amount has a strong substrate temperature dependence,
There is a problem in that it is not easy to control the doping amount when changing the substrate temperature, and furthermore, slight non-uniformity in the temperature within the substrate causes a relatively large non-uniformity in the doping amount. This means that when aiming for highly uniform growth over a large area using the MOCVD method, it is easy to obtain good results regarding the film thickness distribution of the grown layer, but it is difficult to make the doping amount (i.e. the carrier concentration of the grown layer) uniform. The reason is that it is difficult. For example, S IH4, S by GeHa
For i,Ge doping, the decomposition process of the source gas determines the doping amount, so the higher the substrate temperature, the more
Much Si and Ge enter the growth layer. The dependence on the substrate temperature is almost the same for both, and is exponential with respect to the substrate temperature.
~1.16 times with a temperature increase of ℃, ~2 with a temperature increase of 50℃
．． It becomes 1 times. On the other hand, H2S, S by H2S e,
For Se doping, the decomposition of the source gas is sufficiently fast, and the adsorption of S and Se onto the substrate determines the doping amount, so the lower the substrate temperature, the more S and Se enter the growth layer. The dependence on the substrate temperature is almost the same for both, and is also exponential with respect to the substrate temperature, and the temperature range 5 mentioned above is
Between 50°C and 700°C, a temperature drop of 10°C will result in ~1.2
1 times, and becomes ~2.6 times with a temperature decrease of 50°C.

An object of the present invention is to solve the above problems and to make it possible to extremely reduce the dependence of the doping amount on the substrate temperature.
The present invention provides a method for vapor phase growth of a group compound semiconductor.

[Means for solving problems]

The present invention provides a method for vapor phase growth of a -V group compound semiconductor using an organometallic vapor phase growth method, in which at least one of silane (SiH) and germane (G e H4) and hydrogen sulfide are used as doping raw materials. It is characterized by simultaneously using at least one of (H2S) and hydrogen selenide (H2Se).

[Effect]

The dependence of doping amount on substrate temperature is SiH.

Alternatively, the relationship is opposite between the case of GeH and the case of H2S or H2Se. Therefore, 5iH1 and G
e If one or both of Hs and one or both of H2S and H2Se are used at the same time, the substrate temperature dependence can be freely controlled between them, and by selecting an appropriate ratio, the doping amount can be adjusted to the substrate temperature dependence. It is also possible to almost eliminate gender. As a result, even if there is some degree of temperature non-uniformity within the substrate, an extremely uniform doping amount (carrier concentration) distribution within the substrate can be obtained. Further, even if the substrate temperature is changed, a constant doping amount can always be obtained. Furthermore, depending on the purpose, it is also possible to change the mixing ratio of the raw material gases to create a predetermined substrate temperature dependence and make positive use of this dependence.

〔Example〕

Examples of the present invention will be described in detail below.

Trimethyl gallium (TMGa), arsine (ASH3
) was used as a raw material and hydrogen gas was used as a carrier gas. A combination of SiH4 and H2S was selected as the doping raw material, and the target total doping amount (combined Si and S, which is the carrier concentration) was 2 x 101.
I decided on 7cm-3. At a substrate temperature of 600°C, SiH, 1, which corresponds to 55% of this doping amount in the case of alone,
The amount of SiH4 giving IX10170m-3 and the same <0,9
Doping was carried out simultaneously with H2S in an amount giving m-3. The ratio of SiH< and H2S was calculated from the temperature dependence of each doping amount, and was determined so that the rate of change of the doping amount with respect to temperature at 600° C. was zero. As a result, the total doping amount at a substrate temperature of 600°C is the sum of both, 2.OX10170m-3, and when the substrate temperature was significantly changed from 550°C to 650°C and 50°C above and below 600°C, The doping amount increased at both 550°C and 650°C, but the change was less than 20%. As mentioned earlier, the change in doping amount in the case of 3184 or H2S alone is 50
This is an extremely large improvement since it is 2.1 times or 2.6 times as high as ℃.

Also, the variation in doping amount over the entire surface of a 2-inch wafer is about 10% in the case of SiH or H2S alone, which is about 10% if the cause of the variation is all due to non-uniform substrate temperature. The change is estimated to be 6° C., but in the case of simultaneous doping of 455% S i H and 45% H 2 S according to this example, an extremely uniform growth layer of 2% or less was obtained.

〔Effect of the invention〕

As described above, according to the method of the present invention, the dependence of the doping amount on the substrate temperature can be made extremely small in doping with n-type impurities in the MOCVD method, and as a result, the reproducibility of the doping amount is improved. , and also has the effect of significantly improving the uniformity within the substrate surface. Furthermore,
It is also possible to intentionally change the doping amount in the substrate by controlling the substrate temperature dependence to a desired value.

Claims (1)

[Claims] (1) In the vapor phase growth method of III-V compound semiconductors by organometallic vapor phase epitaxy, as a doping raw material,
A III-V compound semiconductor semiconductor characterized by simultaneously using at least one of silane (SiH_4) and germane (GeH_4) and at least one of hydrogen sulfide (H_2S) and hydrogen selenide (H_2Se). Phase growth method.