JPS6170715A - Growing method of compound semiconductor - Google Patents

Abstract

PURPOSE:To obtain a GaAs layer of high quality by cleaning the surface of a substrate of Si or Ge by high temperature treatment, then growing a thin GaAs buffer layer on the (100) substrate at a low temperature, and growing the GaAs layer to be obtained on the buffer layer. CONSTITUTION:To epitaxially grown a GaAs layer on the 100 surface of Si or Ge substrate, the substrate is heat treated under arsenic pressure by removing the surface oxide film of the substrate at temperature for obtaining clean substrate surface. A GaAs buffer layer of 200Angstrom or lower in thickness is grown at 450 deg.C or lower, and the GaAs layer is grown at the growing temperature of the normal GaAs layer. Thus, after high temperature treatment is performed and cleaned, a thin GaAs buffer layer is grown at low temperature, and a GaAs layer to be obtained is grown on the buffer layer at the growing temperature of the normal GaAs layer. Thus, the GaAs layer which has no oval defect and good crystallinity of sole domain can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention applies to silicon (Si) substrates or germanium (germanium) substrates.
The present invention relates to a method for epitaxially growing a gallium arsenide (GaAs) layer on a Ge) substrate.

(Prior Art) With the rapid progress of semiconductor and integrated circuit technology, attempts have been made to form large-scale integrated circuits on large-area substrates or to form three-dimensional circuits. Furthermore, research into solar cells is also active. for that purpose,
For example, it is desirable to form a high quality GaAs single crystal layer on an 81 substrate. However, conventionally 81
Since it has been difficult to grow a GaAs layer directly on a substrate, attempts have been made to first grow some kind of buffer layer on the 81 substrate and then grow the GaAs layer on this buffer layer. and literature (Applied Phys.
icsLetters 38 (10), 15 M
AY 1981, p. 779-781), there are many examples in which a thin film of Ge is used as the gate.

(Problems to be Solved by the Invention) However, when a GaAs layer is grown on the (loo) plane of the 81 substrate, even though the GaAs layer is grown through the Ge buffer layer,
The As layer is an antiphas domain.
As a result, a GaAs layer with sufficient quality crystallinity cannot be obtained.

Furthermore, when Ge and GaAs are successively grown in the same growth apparatus, there is a drawback that Ge is doped in the GaAs layer.

It is an object of the present invention to provide a method for growing a high quality single domain GaAs layer on an 81 or Ge substrate without forming the conventionally used Ge buffer layer.

(Another Means to Solve the Problems) 1 In order to achieve this object, according to the method of the present invention, silicon (Si) or germanium (Ge)
) When epitaxially growing a gallium arsenide (GaAs) layer on the (100) plane of the substrate, the silicon or germanium substrate is placed under arsenic pressure and the surface oxide film of the substrate is removed to obtain a clean substrate surface. A step of heat treatment at a temperature of 45% is applied to the cleaned substrate.
growing a gallium arsenide buffer layer with a thickness of less than or equal to )'x%oo at a temperature of 0° C. or less; and growing a gallium arsenide layer on the buffer layer at a normal gallium arsenide layer growth temperature. and a step of growing.

(Operation) According to the present invention, after the substrate is cleaned by high-temperature heat treatment, a thin GaA layer is grown at a low temperature, and then a thin GaA layer is grown on the buffer layer at a normal GaAs layer growth temperature. Since the desired GaAs layer is grown, a single domain GaAs layer with good crystallinity without so-called oval defects can be obtained.

Furthermore, according to the method of the present invention, a thin GaAs buffer layer is used instead of a Ge thin buffer layer, and the original GaAs layer is formed on top of the thin GaAs buffer layer, so that the GaAs buffer layer and the GaAs buffer layer can be formed in the same growth apparatus. A high quality GaAs layer can be obtained by continuously growing the GaAs layer.

(Example) An example of the method of the present invention will be described below with reference to the drawings. In this example, an 81 substrate was used as the substrate, and trimethylgalium A (Ga(an) was used as the raw material.
, ) a ) and arsine (As Ha ), one GaAs layer is grown on an 81 substrate by the η phase growth method, especially the MOCvD method.
An example of increasing a1 length will be explained.

Figure 11 is a diagram showing the temperature change of the susceptor on which the substrate is placed when carrying out the compound semiconductor growth method of the present invention.In the following explanation, the temperature will be explained using the temperature of the susceptor. , the temperature of the substrate may be 100° higher than the temperature of the susceptor depending on the gas flow rate, the way the gas flows, the shape of the reaction tube, the shape of the susceptor, the temperature to which the susceptor is heated, etc.
”Around C.

It can sometimes go as low as.

First, after placing the 81 substrate on a susceptor in a reaction tube of a vapor phase growth apparatus, the temperature of the susceptor is raised from room temperature while flowing, for example, H2 as a carrier gas (time period shown in FIG. 1). During this temperature rise, the temperature of the susceptor reaches 5
When the temperature reaches 00 to 600°C, in order to perform high-temperature heat treatment by reducing arsenic pressure, in this case AsH3 starts to flow. At this time, the partial pressure of As Ha is at least 0.5 Torr.
It is sufficient if it is in the same position. Furthermore, this As Ha is
After growing a target GaAs layer to be described later, the flow is continued until the susceptor temperature becomes 500° C. or lower.

The susceptor temperature is 81 under arsenic pressure, the temperature at which the surface oxide film of the substrate can be removed and a clean substrate surface can be obtained, e.g. 9
When the temperature reaches 00°C or higher, preferably 900% 950'C, the temperature increase is stopped and the high temperature heat treatment is carried out while maintaining this temperature (time interval -1u shown in Fig. 1). In this case, the heat treatment is performed in an atmosphere of H2 and As Ha, and the treatment time is about 5 minutes.

After this high-temperature heat treatment, the temperature is lowered (time interval TIE shown in FIG. 1) to a temperature of 450° C. or lower, preferably 400° C.
Maintain the temperature at 450℃ and add Ga(OH3) to As Ha.
, 3 was added to the 81 substrate (
lOO) A thin film of GaAs is grown as a buffer layer on the substrate surface (time interval ■ shown in FIG. 1). This GaA
The thickness of the s-buffer layer is about 200 Å or less.

After the growth of this GaAs buffer layer is completed, the susceptor temperature is raised again to about 650 to soo'c, which is the normal growth temperature of the originally intended GaAs layer (time interval V shown in Figure 1). . In this example, this temperature is set to 700
'C. In this temperature raising process, the GaAs buffer layer is annealed, and as a result, the GaAs buffer layer is formed so that the GaAs layer formed thereon becomes a layer with good crystallinity without oval defects. It becomes a high quality buffer layer.

Next, this susceptor was held at 700"C and the GaAs
A GaAs layer is grown on the buffer layer (eleventh time interval ■). Therefore, in addition to an appropriate amount of As Ha to make Ga (CHa) 3 the subcomponent again,
Grow a thin GaAs layer.

After the growth of this GaAs layer is completed, the susceptor temperature is lowered to room temperature (time interval (■) shown in FIG. 1).

In this way, each of the above-described processes in step 1 is performed continuously in the same vapor phase growth apparatus to produce a single domain high-quality GaAs network.
The 81 layer can be grown on the (100) plane of the substrate, and during this series of processing steps, the 81 layer is grown on the (100) plane of the substrate. ) from the growth device.

The above-mentioned high-temperature heat treatment for cleaning the Si substrate is effective even in H3 atmosphere, but if it is performed in an atmosphere of only H3, the polycrystalline GaAs precipitated on the pedestal during the previous growth will re-evaporate and the query - On top of that, there is a risk that it will adhere as fine particles, especially around the periphery of the wafer, and there is a risk that a GaAs layer will not be obtained at the periphery of the wafer, or
At the center of the wafer, redeposited GaAs may become the core of an oval defect. Therefore, in this invention,
During heat treatment, residual GaA precipitated on the pedestal due to the pressure of arsenic, which was obtained by flowing AsH with H and decomposing AsHa.
By suppressing re-evaporation of s, fine GaAs particles are prevented from adhering to the wafer.

Therefore, a single domain high quality GaAs growth layer without oval defects can be obtained over the entire wafer surface.

Furthermore, although the buffer layer is grown at a low temperature, the appropriate growth temperature for the offshore part 7 is +00-450°C.

0 (If the temperature is higher than that, Pl will increase as the temperature increases.
The surface of the target GaAs layer grown on the sofa layer becomes rough, resulting in a layer with poor crystallinity. On the other hand, if the temperature is lowered even further, the growth rate will be significantly slowed down.

Furthermore, although the thickness of the buffer layer was made as thin as 10A or less, if it was made thicker than this, the GaA layer would be grown on top of it.
Oval defects occur in the s-layer and it becomes difficult to form a single domain, resulting in poor crystallinity. but,
The thinner layer may be as thin as several atomic layers.

The invention is not limited to the embodiments described above. For example, although the above embodiment describes an example in which a GaAs layer is grown on an 81 substrate, a high quality GaAs layer can also be grown on a Ge substrate by the same process as that for a Si substrate. In that case, the susceptor temperature during high-temperature heat treatment of the substrate should be set at 600°C or higher, preferably 700°C.
A temperature around C is sufficient.

In addition, in the above-mentioned embodiment, GaAs was
Although layer growth was performed, other conventional vapor phase growth methods can also be used. In that case, raw materials such as arsenic trichloride (AsCA!a) and gallium (!P), Ga, arsine, and hydrochloric acid can be used.

Additionally, any suitable gas other than H3 can be used as the carrier gas.

(Effects of the Invention) As is clear from the above description, according to the present invention, after cleaning the surface of a Si or Ge substrate by high-temperature heat treatment, a thin film of 200A or less is formed on the (100) substrate surface at a low temperature. Since the GaAs buffer layer is grown and the target GaAs layer is grown on this buffer layer, a high quality GaAs layer can be grown.

In addition, the etch bit density of the GaAs layer obtained by this invention is as low as 10 cIL, and the mobility is 5200 cm V for an electron density of lX1Oc*.
-s GaAs grown on GaAs
Since a value close to that of the layer is obtained, it can be used to fabricate a wide variety of GaAs devices.

Furthermore, since a Si or single substrate can provide a substrate with a large area that cannot be obtained with a GaAs substrate, by growing GaAs on this substrate according to the present invention, a large area and high quality GaAs substrate can be obtained.
It is possible to obtain an As layer, and it is possible to fabricate large-scale integrated circuits or three-dimensional circuits in this GaAs layer.
Solar grids can be built using aAs layers.

As mentioned above, all the processing steps for growing a GaAs layer on a substrate can be performed in the same vapor phase growth apparatus without the need for loading and unloading wafers, which prevents contamination or damage to the wafers. Therefore, from this point as well, a high quality GaAs layer can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing temperature changes in a susceptor for explaining the compound semiconductor manufacturing method of the present invention.

Claims (1)

[Claims] 1. In epitaxially growing a gallium arsenide (GaAs) layer on the (100) plane of a silicon (Si) or germanium (Ge) substrate, the silicon or germanium substrate is grown under arsenic pressure and a step of heat-treating the substrate at a temperature that removes the surface oxide film of the substrate to obtain a clean substrate surface;
The method is characterized by comprising the steps of: growing a gallium arsenide buffer layer with a thickness of about Å or less; and growing the gallium arsenide layer on the buffer layer at a normal gallium arsenide layer growth temperature. How to grow compound semiconductors. 2. The method for growing a compound semiconductor according to claim 1, wherein each of the steps is performed successively in the same growth apparatus.