JPH0574717A - Compound semiconductor crystal growth method - Google Patents

Abstract

PURPOSE:To epitaxially grow an atomic layer of good quality using a small quantity of raw gas by enhancing the reactive efficiency of the raw gas by introducing a catalyst into a growth device. CONSTITUTION:A substrate 3 is heated up using a high frequency heater 4. After a quartz reaction tube 1 has been purged by feeding hydrogen gas into it through a valve 7, (CH3)3Ga is vaporized using a bubbler 8, and the (CH3)3Ga is fed into the quartz reactor tube 1 through a switching valve 5. Then, after the quartz reaction tube 1 has been purged by feeding hydrogen gas again, AsH3 is fed through a switching valve 6, and the catalyst 11 introduced into a growth device is heated up using a power source 12. As a result, the partial contact of the AsH3 to be fed as the raw material of arsenic, is accelerated by a catalytic action, and the feeding efficiency of arsenic can be improved. Accordingly, an atomic layer can be grown by a little feeding quantity of AsH3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for growing a compound semiconductor crystal, and more particularly to an improved method for increasing the reaction efficiency of a raw material gas to enable good atomic layer epitaxy with a small amount of the raw material gas.

Compound semiconductor crystals and impurities thereof are used for the purpose of developing electronic devices having new functions by advancing the miniaturization of electronic devices to improve their performance, and also to realize physical properties not found in conventional bulk materials. It is strongly desired to control the concentration in atomic layer units.

[0003]

2. Description of the Related Art FIG. 2 shows a schematic diagram of an atomic layer epitaxial growth apparatus. In the figure, 1 is a quartz reaction tube,
2 is a carbon susceptor for holding the substrate 3, 4 is a high-frequency heater for heating the substrate 3, 5, 6, and 7 are switching valves for switching the gas supplied to the quartz reaction tube 1, and 8 is It is a bubbler that vaporizes raw materials.
Is an exhaust port, and 10 is a pressure control means for controlling the pressure in the quartz reaction tube 1.

For example, when growing a gallium arsenide (GaAs) crystal, trimethylgallium ((CH ₃ ) ₃ Ga) is used as a gallium raw material and arsine (AsH ₃ ) is used as an arsenic raw material. The process of heating the substrate 3 to a temperature of 500 ° C. using the high frequency heater 4 and alternately supplying the hydrogen gas for purging and the raw material gas into the quartz reaction tube 1 is repeated according to the schedule shown in Table 1. ..
That is, first, hydrogen gas is supplied to the
After supplying for 2 seconds into the quartz reaction tube 1 and purging, (CH ₃ ) ₃ Ga is vaporized using a bubbler 8 held at a temperature of 3 ° C., and the vaporized (CH ₃ ) ₃ Ga is switched to a valve 5. Is supplied to the quartz reaction tube 1 for 4 seconds with a supply amount of 40 SCCM. Next, hydrogen gas is again supplied for 3 seconds to purge, and then AsH ₃ is supplied through the switching valve 6 for 3 seconds with the supply amount xSCCM. Hydrogen and source gas are exhausted through the switching valves 5, 6, and 7 while the quartz reaction tube 1 is not supplied. The pressure inside the quartz reaction tube 1 is controlled to about 20 Torr by the pressure control means 10.

[0005]

[Table 1] From this growth result, the relationship between the ratio of the growth film thickness per cycle to the thickness of the monolayer and the supply amount (x) of AsH ₃ is obtained, and the graph shown in FIG. 4 is obtained.

As for (CH ₃ ) ₃ Ga, FIG.
It has been confirmed that the growth film thickness per cycle becomes one molecular layer thickness when the supply time is 4 seconds or more, as shown in FIG.

[0007]

In atomic layer epitaxy, reactions that contribute to growth occur only on the substrate surface,
Moreover, the reaction temperature is set low. Further, the raw material gas is exhausted to the outside of the apparatus while it is not being supplied into the quartz reaction tube 1. Therefore, the reaction efficiency of the source gas in atomic layer epitaxy is remarkably lower than that in the ordinary vapor phase growth method. Particularly, in the case of AsH ₃ which is a raw material of arsenic, the supply amount cannot be reduced to 200 SCCM or less as shown in FIG. 4, so that the reaction efficiency is extremely low.

An object of the present invention is to eliminate this drawback, and to provide a compound semiconductor crystal growth method which improves the reaction efficiency of the source gas and enables high quality atomic layer epitaxy with a small amount of the source gas. is there.

[0009]

SUMMARY OF THE INVENTION The above-mentioned object is to provide a compound semiconductor crystal growth method in which source gases of elements constituting a compound semiconductor are alternately supplied to a growth apparatus, and a catalyst is provided in the growth apparatus. It is achieved by introducing. The catalyst is preferably platinum, nickel, molybdenum, or tungsten,
Further, it is preferable to heat the catalyst in synchronization with the supply of the specific raw material gas. Further, gallium and arsenic are preferable as the elements constituting the compound semiconductor, and arsenic source gas is preferable as the specific source gas.

[0010]

[Action] For example, in the case of growing a GaAs crystal, AsH ₃ supplied as a raw material of arsenic, because decomposed by the catalytic action of platinum or the like is promoted to improve the efficiency of supply of arsenic (As), a small amount of AsH ₃ Amount of supply enables atomic layer growth. The decomposition of AsH ₃ can be further promoted by heating the catalyst, but if the decomposition of (CH ₃ ) ₃ Ga, which is a raw material of gallium, is promoted, the self-limiting effect cannot be obtained, which is preferable. Therefore, in this case, the catalyst is heated only during the period of supplying AsH ₃ .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A compound semiconductor crystal growth method according to an embodiment of the present invention will be described below with reference to the drawings by taking as an example the case of atomic layer epitaxial growth of a GaAs layer on a GaAs substrate.

FIG. 1 is a block diagram of an atomic layer epitaxial growth apparatus. The same parts as those shown in FIG. 2 are shown by the same symbols, and 11 is a catalyst according to the present invention, and platinum, nickel, molybdenum, tungsten or the like is used for the catalyst. 12 is a power source for heating the catalyst.

Using the high frequency heater 4, the substrate 3 is set to 500
Heat to a temperature of ° C and follow the schedule shown in Table 2.
Hydrogen gas for raw material and source gas are alternately placed in the quartz reaction tube 1.
The supplying step is repeatedly executed for 177 cycles. Sanawa
First of all, the hydrogen gas is first passed through the switching valve 7 for 3 seconds.
After supplying into the UK reaction tube 1 and purging, keep the temperature at 3 ° C.
Use the bubbler 8 you have (CH₃)₃Vaporize Ga
Let it vaporize (CH₃) ₃Switching Ga through valve 5
Then, in the quartz reaction tube 1 for 4 seconds with a supply amount of 40 SCCM
Supply to. Next, supply hydrogen gas again for 3 seconds and
Then, the AsH via the switching valve 6₃Supply amount
Supply with xSCCM for 3 seconds. AsH₃Supply
During a certain period, the power supply 12 is used to heat the catalyst 11. In addition,
The pressure in the quartz reaction tube 1 is 20T by the pressure control means 10.
held in orr.

[0014]

[Table 2]

From the above growth results, the relationship between the ratio of the grown film thickness per cycle to the monolayer thickness and the AsH ₃ supply amount x is obtained, and the graph shown in FIG. 5 is obtained. AsH
Atomic layer epitaxial growth was possible even when the supply amount of ₃ was reduced to about ₃ SCCM, and the supply amount of AsH ₃ could be reduced to 1/50 or less of that in the conventional technique.

The installation area of the catalyst 11 is not limited to the inlet of the reaction tube 1 as shown in FIG. 1, but may be installed in a specific gas supply circuit, in this example, an AsH ₃ supply circuit. Needless to say.

[0017]

As described above, the compound according to the present invention
In the semiconductor crystal growth method, a catalyst is
For example, when growing GaAs by introducing
Is the raw material AsH₃Decomposition of arsenic is promoted and arsenic supply efficiency
As a small amount of AsH ₃Atomic layer with supply
Epitaxial growth becomes possible, and atomic layer epitaxy technology
This will greatly contribute to the practical application of surgery.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an atomic layer epitaxial growth apparatus used for carrying out a compound semiconductor crystal growth method of the present invention.

FIG. 2 is a configuration diagram of an atomic layer epitaxial growth apparatus used for carrying out a prior art compound semiconductor crystal growth method.

FIG. 3 is a graph showing the relationship between the ratio of the growth film thickness per cycle to the monolayer thickness and the (CH ₃ ) ₃ Ga supply time.

FIG. 4 is a graph showing the relationship between the ratio of the growth film thickness per cycle to the monolayer thickness and the AsH ₃ supply amount in the conventional technique.

FIG. 5 shows the growth film thickness per cycle in the present invention.
Ratio to 1 molecular layer thickness and AsH ₃Show relationship with supply
It is a graph.

[Explanation of symbols]

 1 quartz reaction tube 2 susceptor 3 substrate 4 high frequency heater 5, 6, 7 switching valve 8 bubbler 9 exhaust port 10 pressure control means 11 catalyst 12 power source for catalyst heating

Claims (3)

[Claims] 1. A compound semiconductor crystal growth method in which source gases of respective elements constituting a compound semiconductor are alternately supplied to a growth apparatus to form a film in atomic layer units, wherein a catalyst is introduced into the growth apparatus. A method for growing a compound semiconductor crystal, which comprises: 2. The method for growing a compound semiconductor crystal according to claim 1, wherein the catalyst is heated in synchronization with the supply of a specific source gas. 3. The compound semiconductor crystal growth method according to claim 2, wherein the elements constituting the compound semiconductor are gallium and arsenic, and the specific source gas is a source gas of arsenic.