JPS6253933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor crystal growth apparatus for growing semiconductor crystals having two or more elemental components by a vapor phase method.

The vapor phase method, which is one of the methods for growing semiconductor crystals, uses Si
is already commonly used.

FIG. 1 shows an example of a cross section of a Si vapor phase epitaxial growth apparatus. In FIG. 1, a Si substrate 1 is placed on an inclined substrate setting plate 2 and set inside a quartz tube 3. In order to grow the crystal, the temperature of the substrate setting plate 2 is increased using high frequency, and the temperature of the substrate 1 is controlled to a predetermined temperature. Although not shown, growth source gas, e.g.
SiCl ₄ is supplied onto the Si substrate 1 from the left side (arrow 4 side) in FIG. 1 using hydrogen as a carrier gas. Since the Si substrate is heated to the desired temperature,
Si precipitates. In order to control the electrical conductivity and conductivity type of the grown layer, an impurity gas such as PH ₃ or B ₂ H ₆ is mixed in advance into the SiCl ₄ gas at a predetermined concentration, and then the mixture is This is done by supplying gas onto the Si substrate 1. In this way the second
As shown in the cross section of the grown layer, a grown layer Si6 having a desired electrical conductivity can be grown on the Si substrate 5.

In such a case, if the impurity concentration of the substrate 5 is high and the impurity concentration of the growth layer 6 is low, there is a stop layer that contributes to so-called autodoping and its effects, so that the relationship between the substrate 5 and the growth layer 6 is low. It is difficult to obtain crystals with a steep concentration profile at the interface.
Furthermore, when the conductivity type of the growth layer 6 is changed to increase the number of growth layers 6, since the volume from the place where the supply gas is switched to the substrate is large, it takes time to replace the gas, and the growth layer 6 has a steep slope. The disadvantage is that a significant change in conduction type cannot be realized.

The present invention has been made in view of these drawbacks.
By providing a growth gas supply section with an opening close to the substrate, and further providing at least one of an etching gas supply section or a scavenging gas supply section close to the growth gas supply section, the above-mentioned method can be achieved. To provide a semiconductor crystal growth apparatus which eliminates the drawbacks of small concentration changes and conductivity type changes in conventional apparatuses, and which can be usefully applied to - group compound semiconductor crystals and their mixed crystals, etc., which have recently been rapidly becoming necessary. It is an object.

An embodiment of this invention will be described with reference to FIG.

Figure 3a is a schematic cross-sectional view of the growth apparatus, and Figure 3b is a schematic cross-sectional view of the growth apparatus.
is a cross-sectional view taken along line AA' in FIG. 3a, and the gas supply system and substrate heating power source are not shown.

An example will be described using as an example a method in which InP, which is one of the - group compound semiconductor crystals, is grown in a vapor phase.

In FIG. 3a, 7 is an InP substrate, 8 is a substrate setting heating plate which is rotatable, and 9 is a heating high frequency coil, the lead wire 10 of which is connected to a heating power source. Reference numeral 12 designates four growth gas supply pipes, each of which opens close to the substrate 7 to supply each growth gas directly above the substrate 7. 11 and 13 are the growth gas supply pipes 12, respectively.
an etching gas supply pipe installed close to the
The scavenging gas supply pipe 14 is a gas discharge port. When actually growing a crystal, it is performed as follows. The pre-treated InP substrate 7 is placed in the third
Set as shown in Figure a. The temperature is raised to a predetermined temperature in a desired atmospheric gas. At this time, PH ₃ is poured to prevent P from evaporating from the InP substrate 7.
Before crystal growth, a substrate etching gas is supplied onto the substrate 7 from the gas supply pipe 13 to clean the surface of the InP substrate 7. Next, hydrogen gas, which is a scavenging gas, is supplied from the gas supply pipe 11 to remove the etching gas. Immediately after the removal, the hydrogen gas is stopped, and a predetermined partial pressure of, for example, In
(C ₂ H ₅ ) ₃ at a predetermined partial pressure of PH ₃ from the other one.
It is supplied onto the InP substrate 7. By supplying gas for a predetermined period of time, a desired thickness of the grown layer can be obtained. Here, although In(C ₂ H ₅ ) ₃ and PH ₃ are substances that can react with each other, in the semiconductor crystal device configured as described above, the gas supply pipe 1 for crystal growth is
Since the opening 2 is provided close to the substrate 7, it is possible to prevent the In(C ₂ H ₅ ) ₃ and PH ₃ from reacting with each other and producing undesirable substances before reaching the substrate 7. ,rare. When stopping growth, the supply of growth gas is stopped and at the same time the tube 1 is
1, hydrogen gas is supplied to remove the growth gas remaining on the InP substrate 7, and the temperature is lowered.

In this way, InP can be grown on the InP substrate 7. In addition, in order to obtain a uniform growth layer,
The InP substrate 7 is rotated by the substrate setting heating plate 8. When it is necessary to add impurities to the growth layer, the other one of the gas supply pipes 12 can be used to dope the impurities.

For example, a predetermined partial pressure of In(C ₂ H ₅ ) ₃ , Ga(C ₂ H ₅ ) ₃ , AsH ₃ ,
By supplying PH ₃ onto the InP substrate 7, a quaternary compound semiconductor crystal of a predetermined composition, InxGa ₁ -xAs ₁ -yPy
can be grown. In this case, in particular, in order to change the composition in a stepwise manner and grow two or more layers, the partial pressure ratio of these component gases to be supplied is changed in a stepwise manner.
It must be supplied onto the substrate 7.

According to this device, the volume from the growth gas supply pipe to the substrate is small, and the gas supply pipe for residual gas removal is provided in close proximity, so that the growth gas and the residual gas removal gas can be mixed as desired. By setting the flow rate and time, it is possible to change the composition of the growth layer and grow it in a stepwise manner. It is obvious that if the composition of the growth layer can be controlled stepwise, growth can be achieved by gradually changing the composition. In addition, in order to dope impurities with this quaternary compound, the number of gas supply pipes required as independent gas supply pipes, that is, 1 or 2.
This can be easily done by increasing the number of Moreover, the gas supply pipes 11 to 13 do not have to be tubular, but may be any gas supply portion having a gas supply passage.

As is clear from the above description, according to the present invention, since the growth gas supply section is provided close to the substrate, a plurality of types of crystal growth gases that can react with each other are supplied from the growth gas supply section. Even if the crystal growth gas is used, it is possible to prevent the crystal growth gases from reacting with each other before reaching the substrate, resulting in a high-quality grown crystal.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional Si vapor phase growth apparatus, Figure 2
The figure is a cross-sectional view of a Si grown layer using the apparatus shown in FIG. 1, and FIG. 3 is a cross-sectional view showing an embodiment of the vapor phase growth apparatus according to the present invention. In the figure, 7 is an InP substrate, 8 is a substrate setting heating plate, 9
1 is a heating high-frequency coil, and 11 to 13 are gas supply pipes.

Claims (1)

[Claims] 1. In a semiconductor crystal growth apparatus for vapor-phase growth of semiconductor crystals having two or more elemental components, each opening is adjacent to a growth substrate on a heating plate, and a plurality of types of growth elements or their compositions are capable of reacting with each other. A semiconductor crystal growth apparatus comprising a plurality of crystal growth gas supply units each independently supplying a crystal growth gas directly above the growth substrate using a carrier gas.