JPH0684792A - Manufacture of thin film - Google Patents

Abstract

(57) [Summary] [Purpose] Good quality Ga on Si [100] just substrate.
Provided is a method capable of forming an As thin film or the like at a low substrate processing temperature. [Structure] A GaAs thin film or the like is grown on the surface of a Si [100] just substrate while forcibly giving a temperature gradient such that the central portion is 650 ° C. and the peripheral portion is 560 ° C.

Description

Detailed Description of the Invention

[0001]

The present invention relates to GaAs on a Si substrate.
Etc. to a method for forming a compound semiconductor thin film.

[0002]

2. Description of the Related Art For example, when a GaAs thin film is deposited on a Si [100] substrate, the off-substrate (2 to 1 in the [011] direction is
(Inclined by 4 °) is heated once to about 1000 ° C, and then, at first, at a low substrate temperature of 200 to 400 ° C, GaA with a film thickness of several tens of liters
It is common to employ a two-step growth method in which an s buffer layer is grown, and then a GaAs layer having a thickness of 2 to 3 μm is grown at a high substrate temperature of 600 to 750 ° C.

One of the factors for using the off-substrate in this way is to forcibly set the direction of the step, and the heating before the growth has a role of making the height of the step equal to two atoms. It is said. Then, when forming the GaAs thin film, unless an off-substrate is used and high-temperature heating before growth is not performed, a single domain is not formed and a good quality crystal cannot be obtained. In other words, when the domain is not a single domain, parameters such as electron mobility showing crystallinity are deteriorated.

[0004]

As described above, Ga
When growing a compound semiconductor such as As or GaP on a Si [100] substrate, off-substrate and high temperature heating before growth are indispensable requirements. However, this is a major obstacle in manufacturing a device in which a Si device and a GaAs device are combined on the same Si substrate.

That is, the Si device is usually formed on a Si [100] just substrate having no inclination, and the composite device is a procedure for producing a GaAs device after the processing of the Si device is completed. Therefore, it is practically impossible to perform high temperature heating before the growth of the GaAs film after the Si device is manufactured, because it causes the destruction of the Si device.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a method for forming a good quality GaAs thin film or the like on a Si [100] just substrate at a low substrate processing temperature. To provide.

[0007]

To achieve the above object, in the method of the present invention, a predetermined temperature gradient is forced on a Si [100] just substrate along a direction parallel to its thin film forming surface. In this state, a compound semiconductor thin film is grown on the surface of the substrate.

[0008]

GaAs is formed on a Si [100] just substrate with a temperature gradient such that the central portion of the film forming surface is 650 ° C and the peripheral portion is lower than that by about 100 ° C. As a result, a single domain GaAs thin film could be obtained without heating the substrate at high temperature before film growth.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram of a thin film manufacturing apparatus used for carrying out the method of the present invention.

In the vacuum chamber 1, two evaporation sources, a Ga evaporation source 2 and an As evaporation source 3, are arranged. Each of the evaporation sources 2 and 3 has a vapor deposition material Ga or As inside.
Crucibles 21 and 31 for accommodating the heating element and the heating filament 2
2, 32, etc., and heating filaments 22, 32
The evaporation material inside each crucible is vaporized by heating by the. Then, the vaporized vapor deposition material blows out from the injection holes 21a and 31a of each crucible to form a cluster, which advances in the vacuum chamber 1 and both clusters reach the same substrate S.

On the cluster advancing path between the evaporation sources 2 and 3 and the substrate S, ionization units 4 and 5 and acceleration electrodes 6 and 7 are sequentially arranged. Further, shutters 8 and 9 are provided between the acceleration electrodes 6 and 7 and the substrate S, respectively. By operating the shutters 8 and 9, the substrates S of the clusters from the evaporation sources 2 and 3 are disposed. You can choose to proceed to.

The substrate S is held at a predetermined position in the vacuum chamber 1 by a holder 10 provided with a heater and a thermocouple, and the substrate S is given a temperature gradient described later.

Now, using the apparatus described above, Si
The procedure for forming a GaAs thin film on a substrate will be described below. First, a 4-inch Si [100] just substrate S is mounted on the holder 10 in the vacuum chamber 1, and the center of the film forming surface is 650 ° C. and the peripheral portion is 560 ° C. on the substrate S.
By forcibly giving a temperature gradient such that
A portion of the As cluster beam ejected from the evaporation source 3 is ionized and irradiated on the surface of the substrate S to clean the substrate S.

Thereafter, the surface of the substrate S is irradiated with a Ga ionized cluster beam and an As ionized cluster beam while accelerating at a voltage of about 1.3 KV, and a buffer layer is laminated on the surface of the substrate S. The thickness of this buffer layer is 1.5μ
It is about m.

Finally, stop ionization and acceleration,
The surface of the substrate S is irradiated with a neutral Ga cluster beam and an As cluster beam to form Ga on the previously stacked buffer layer.
Grow an As thin film. The thickness of this thin film is also about 1.5 μm.

The surface morphology (SEM observation) of the GaAs thin film obtained by the above procedure is shown in FIG. 1 (a). In this figure, the surface morphology of each position of the substrate S is partially shown, and the temperature distribution of the substrate S is also shown.

From this surface morphology, the [00
It was found that the 1] direction and the neighboring region in the direction orthogonal thereto are not single domains and have poor crystallinity, but other regions are single domains (Fig.
(See (b)). Moreover, the dislocation density of a single domain is 2 ×
It was confirmed to be as small as 10 ⁶ cm ^-2 and the crystallinity was good.

Here, even with a Si [100] just substrate, by what kind of mechanism can a GaAs thin film having a single domain and good crystallinity be obtained only by applying the above temperature gradient? Although it is not clear, the prospect of the fact that the method of the present invention makes it possible to produce good quality GaAs / Si at a low substrate processing temperature (650 ° C.) by a very simple method.

If the temperature gradient applied to the substrate is about 90 to 100 ° C. per 2 inches, the same result as above can be obtained even if there is a slight difference in the maximum temperature at the center of the substrate. Moreover, even when the sizes of the substrates are different, it is presumed that the same result can be obtained by applying the temperature gradient of the above degree. Furthermore, the same result may be obtained when the film is formed by applying a temperature gradient opposite to the above to the substrate, that is, a temperature gradient that decreases from the peripheral edge of the substrate toward the center. Is enough.

In the above embodiments, the ion deposition method is used as a film forming method.
Although the cluster beam method is adopted, the method of the present invention can be implemented by using other film forming methods such as the MBE method.

In addition to the GaAs thin film, the method of the present invention can be applied to the film formation of other compound semiconductor thin films such as GaP.

[0022]

As described above, by adopting the method of the present invention, it is possible to obtain a good quality GaAs thin film on a Si [100] just substrate at such a low substrate processing temperature that the Si device is not destroyed. Thus, in the future, when constructing a composite device using, for example, GaAs / Si, the possibility of its realization is greatly increased.

[Brief description of drawings]

FIG. 1 (a) is a diagram partially showing the surface morphology (SEM observation) of a GaAs thin film obtained by the method of the present invention, and FIG. 1 (b) is an explanatory diagram of the result of consideration of the quality of the GaAs thin film.

FIG. 2 is a schematic configuration diagram of an apparatus used for carrying out the method of the present invention.

[Explanation of symbols]

 1 ... Vacuum chamber 2 ... Ga evaporation source 3 ... As evaporation source 4,5 ... Ionization part 6,7 ... Accelerating electrode S ... Si [100] Just board

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[Procedure amendment]

[Submission date] March 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 (a) is a SEM partially showing the surface crystal structure (morphology) of a GaAs thin film obtained by the method of the present invention.
Photo and (b) are illustrations of the results of consideration of the quality of the GaAs thin film.

FIG. 2 is a schematic configuration diagram of an apparatus used for carrying out the method of the present invention.

Claims (1)

[Claims] 1. A Si [100] just substrate is forcibly given a predetermined temperature gradient along a direction parallel to its film forming surface, and in this state, a compound semiconductor thin film is grown on the substrate surface. A thin film manufacturing method characterized by the above.