JPS6019135B2 - Vapor phase growth method for compound semiconductors - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for vapor phase growth of compound semiconductors, and more specifically, the present invention relates to a method for vapor phase growth of compound semiconductors. The present invention relates to a compound semiconductor vapor phase growth method that simultaneously produces epitaxial growth layers on a plurality of crystal substrates.

Although the present invention will be described below in connection with the vapor phase growth of an epitaxial layer of gallium oxide (GaAs), the method of the present invention can also be applied to the vapor phase growth of other compound semiconductors.

Generally, when an epitaxial layer of gallium chloride is grown in a vapor phase, a horizontal vapor phase growth apparatus shown schematically in FIG. 1 is used.

First, a source boat 3 loaded with metal gallium (Ga) 2 and a substrate holder 5 supporting a crystal substrate 4 are placed in a reaction tube 1 . This reaction tube 1 is heated in a horizontal furnace (not shown) to create a temperature distribution inside the reaction tube 1 as shown in FIG. Using hydrogen (specific) gas or nitrogen (N2) gas as a carrier gas, this carrier gas is directly introduced into the reaction tube 1 through a tube 6, and is also passed through a silicon trichloride (AsC13) 8 through a tube 7. AsC13C
Gas is introduced into the reaction tube 1. In this way, Ga CI3 from metallic gallium reacts in the reaction tube 1 to produce magnetized gallium (GaAs), which is deposited on the crystal substrate 4 to form an epitaxial crystal layer. The gas after the growth reaction is exhausted from the exhaust port 16. However, in the vapor phase growth method using the above-mentioned vapor phase growth apparatus, it is not possible to simultaneously grow epitaxial crystal layers on a large number of crystal substrates.

Therefore, the present applicant has decided to
No. 0147017) proposed a horizontal vapor phase growth apparatus for compound semiconductors that can grow crystals on multiple crystal substrates at the same time. In this proposed growth apparatus, as shown in FIGS. 3 and 4, four crystal substrates 11, 12,
13 and 14 are arranged in the shape of a hollow square prism, and epitaxial crystal layers are simultaneously grown in a vapor phase on these crystal substrates.

Figure 3 is a perspective view of the crystal substrate and substrate holder;
The figure is a cross-sectional view illustrating the state when the crystal substrate and substrate holder shown in FIG. 3 are placed in the reaction tube. The proposed vapor phase growth apparatus is the same as the conventional apparatus except that the crystal substrate holder in the conventional horizontal vapor phase growth apparatus is replaced with the substrate holder 15 shown in FIG. The vapor phase growth method is carried out using the same procedure as the secondary method. When a compound semiconductor (GaAs) was grown in the vapor phase on a crystal substrate using this proposed growth apparatus, the relationship between the vapor phase growth rate and each crystal substrate (crystal substrate position) was as shown in Figures 5 and 6. Ta.

FIG. 5 shows the case where gallium chloride vapor phase growth is performed using nitrogen gas as a carrier gas, and the crystal substrate 12 is
The growth rate is almost the same for crystal substrates 11 and 14 (positions on the left and right sides of a regular square prism), but crystal substrate 11 (position on the top surface)
The growth rate is a little higher than that of the crystal substrates 12 and 14, and the growth rate of the crystal substrate 13 (lower surface position) is a little lower than that of the crystal substrates 12 and 14. Also,
Figure 6 shows the case of magnetized gallium vapor phase growth using hydrogen gas as the carrier gas, and contrary to the case of Figure 5, the growth rate is slightly lower on the crystal substrate 11 (top surface position). The crystal substrate 13 (lower surface position) is slightly larger. As described above, there is a drawback that the vapor phase growth rate varies depending on the location of the crystal substrate, that is, there is a drawback that the thickness of the epitaxial growth layer grown at the same time varies. Therefore, an object of the present invention is to suppress the above-mentioned disadvantageous variation as low as possible and to make the thicknesses of the epitaxial crystal layers simultaneously grown in a vapor phase substantially equal.

The above object is achieved by the following compound semiconductor vapor phase growth method.

In other words, this vapor phase growth method involves arranging a plurality of crystal substrates so as to form the side walls of a hollow regular polygon with the center axis of the vapor growth reaction tube as the central axis, and depositing compound semiconductors on these crystal substrates. A compound semiconductor characterized in that, in the vapor phase growth method, the carrier gas used for vapor phase growth of the compound semiconductor is a mixed gas of 25 to 75% hydrogen gas and 75% to 25% nitrogen gas. This is a vapor phase growth method.
When an epitaxial crystal layer is grown on the crystal substrate shown in FIGS. 3 and 4 by applying the growth method according to the present invention,
The relationship between the vapor phase growth rate and each crystal substrate (crystal substrate position) becomes as shown in FIG. 7, and there is almost no difference in growth rate depending on the crystal substrate position.

In addition, the carrier gas in the case of Fig. 7 is hydrogen gas at 36V.
Nitrogen gas is 64 vol% in ol%. If the hydrogen gas is less than the specified 25%, this means that the nitrogen gas is 7%
This is more than 5%, and a relationship between growth rate and substrate position as shown in FIG. 5 appears, resulting in a difference in growth rate. Conversely, when the hydrogen gas content is more than 75%, a tendency as shown in FIG. 6 appears, and a difference in growth rate occurs. Therefore, especially from the point of view of practical quality control, it is necessary to specify the above-mentioned gas mixture ratio in order to suppress the variation in the vapor phase growth rate within ±2%. Although it is preferable that the above-mentioned regular polygonal prism is a regular square prism, it may be a regular pentagonal prism or a regular hexagonal prism. The crystal substrate should be arranged in an appropriate hollow polygonal column shape, taking into consideration the inner diameter of the reaction tube, the size of the crystal substrate, etc. The invention will be explained by examples.

EXAMPLE Using the compound semiconductor vapor phase growth method according to the present invention, gallium sulfide was grown in the vapor phase under the following conditions.

Vapor phase growth conditions〉 Crystal substrate: Gallium sulfide wafers (20×3×4 wafers) Crystal substrate arrangement: Arranged as shown in Figures 3 and 4 Growth temperature: 73 and 0 ship CI3 temperature: 3 is O Ga source temperature: 850qC Reaction tube internal temperature: 44 side carrier gas: Hydrogen gas (36 vol%) + nitrogen gas (64 vol%) Bypass carrier gas flow rate: 70 ratio c/min ASC13 bubbling Carrier gas flow rate used for: 30 c/min Results> Average vapor growth rate: 0.15 m/min Variation in vapor growth rate: Within 2% using a horizontal vapor growth apparatus By applying the method of the present invention when growing epitaxial crystal layers on a large number of crystal substrates, the difference in growth rate depending on the placement position is as small as ±2% or less, that is, the growth rate on all crystal substrates is reduced. can be made almost the same.

Therefore, it becomes possible to mass-produce products of stable quality with very small differences in the thickness of the vapor-grown crystal layer.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram of a horizontal vapor phase growth apparatus for normal abrasive gallium vapor phase growth, and Fig. 2 is a schematic illustration of the horizontal vapor phase growth apparatus of Fig. 1. FIG. 3 is a temperature distribution diagram inside the reaction tube.
FIG. 4 is a perspective view when four crystal substrates are arranged in a hollow square prism shape, and FIG. 4 is a cross-sectional view illustrating the state when the crystal substrates and substrate holder of FIG. 3 are arranged in a reaction tube. Figure 5 shows the relationship between the vapor phase growth rate and the crystal substrate position when epitaxial crystals are grown using nitrogen carrier gas on the crystal substrates arranged as shown in Figures 3 and 4. Fig. 6 is a diagram representing Fig. 3 and Fig. 4.
FIG. 7 is a diagram showing the relationship between the vapor phase growth rate and the position of the crystal substrate when an epitaxial crystal is grown using a hydrogen carrier gas on the crystal substrate arranged as shown in the figure. , is a diagram showing the relationship between the vapor phase growth rate and the crystal substrate position in an embodiment of the growth method according to the present invention (mixed carrier gas of 36 vol% hydrogen gas and 64 vol% nitrogen gas). 1...Reaction tube, 2...Gallium source, 4... ...Crystal substrate, 5...Substrate holder, 6,7...Carrier gas supply pipe, 8...
...Ship CI3, 11, 12, 13, 14...
Crystal substrate, 15...Substrate holder, 16...Exhaust port. Fig. 1 Fig. 2 Fig. 3 Younger sister Fig. 5 Fig. 6 Fig. 7

Claims (1)

[Claims] 1. A method for vapor-phase growing a compound semiconductor on a crystal substrate by arranging a plurality of crystal substrates so as to form a side wall surface of a hollow regular polygon whose central axis is the central axis of a vapor-phase growth reaction tube, The carrier gas used in the vapor phase growth of compound semiconductors is 25 to 75% hydrogen gas and 75 to 25% hydrogen gas.
% of nitrogen gas.