JPS63276215A - Vapor growth device - Google Patents

Abstract

PURPOSE:To grow high purity crystal containing As by a method wherein the crystal containing arsenic is brought into contact with the raw gas containing As, and the impurities contained in the raw gas, especially sulfur is taken into the crystal. CONSTITUTION:The raw gas cotaining arsenic is introduced from introducing pipes 14, 15, 16 and 17, and it is decomposed by heat. At that time, an arsenic- cotaining III-V compound semiconductor 26 is taken into a quartz boat 25 and arranged in the path of the raw gas containing arsenic located on the part which will be dissolved by heat. Pipes 18 and 20, with which the group V gas such as arsine, phosphine and the like, and pipes 19 and 21 through which the doping gas such as H2S and the like will be made to flow are connected to the upper chamber 8 and the lower chamber 9 respectively. Consequently, high purity crystal containing As can be grown.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a vapor phase growth apparatus for growing high-purity crystals with good reproducibility in compound semiconductors containing arsenic as an element.

(Prior Art) Examples of growing an InGaAs layer on an InP substrate by a vapor phase open tube method include a hydride vapor phase epitaxy method, a chloride vapor phase epitaxy method, and an organometallic vapor phase epitaxy method. Among these growth methods, the one that can stably obtain the highest purity is chloride vapor phase growth. Taking the case of growing GaAs as an example, in the chloride method, Ga metal Ic
When AsCJ is flowed, an ic GaAm paste is formed on the Ga metal and becomes saturated, after which Ga chloride and As molecules are transported downstream to grow GaAs on the substrate. Both G emmetal and kscLB can be obtained with high purity, and furthermore, the Ga metal and GaAl crust have an impurity gettering effect. Therefore, a high purity GaAs crystal can be grown.

In contrast, in the hydride vapor phase growth method, HCJ gas is flowed over Ga metal and transported as Ga chloride.
In addition, AsH and gas are flowed through another introduction pipe, and A3 is thermally decomposed.
Transport as molecules. HCJ-gas, AsH, gas can be obtained with high purity.
It is difficult to obtain highly pure crystals. Regarding HCJ gas, A
High purity HCJ may be obtained by thermal decomposition of sCj. In addition, by increasing the gettering effect of impurities by increasing the Ga metal source temperature, HC
，! Impurities contained in the gas can be reduced. However, since there is no means to efficiently remove impurities in AsH, these impurities are incorporated into the crystal, causing fluctuations in the carrier concentration of the pack ground. In addition to impurities in the gas, impurities that may be incorporated into the crystal include H! of the carrier gas from the quartz reaction tube (8i0.). There is a compound of Sl that is reduced and liberated from the reaction tube.

In order to suppress this Sl uptake, a trace amount of O! Add S
Attempts have been made to emit it as an oxide of t.

In the case of organometallic vapor phase epitaxy, only the substrate is heated, and the surrounding area is only affected by thermal radiation and convection, so hot walls are not used as in the case of hydride vapor phase epitaxy and chloride vapor phase epitaxy. Therefore, it is thought that there is almost no release of 81 from the quartz reaction tube. Further, although a Bi substrate is sometimes used as a susceptor on which a growth substrate is placed, decomposition of St does not occur because the growth temperature is 800° C. or lower. Impurities in organometallic vapor phase epitaxy are organometallic (TMG or
It is thought that this is an impurity in the volatile component AsH in TEG.

(Problems to be Solved by the Invention) Impurities, especially those containing sulfur, in the V group hydride gas in the conventional hydride vapor phase epitaxy method are difficult to remove and become an obstacle to high purity. ing. Furthermore, the background carrier accumulation level fluctuates due to the variation K in the degree of impurity a for each gas slot, which becomes a factor that makes concentration control difficult.

The impurity concentration in the crystal, 1011cIL, is 0.1cIL in the gas.
1pI)m or less, and direct analysis is technically difficult.

An object of the present invention is to provide a vapor phase growth apparatus capable of removing impurities in gas containing arsenic, particularly those containing sulfur.

[Structure of the invention]

(Means for Solving the Problems) The present invention uses high-purity GaAs to remove impurities in a source gas containing As, particularly those containing sulfur.

Adsorption is performed using a crystal containing As, such as an InGaAs crystal.

That is, a crystal containing arsenic is brought into contact with a source gas containing As at a high temperature, and impurities, particularly sulfur, contained in the source gas are incorporated into the crystal, thereby preventing the impurities from being transported to the downstream substrate.

(Function) Impurities that may become donors in a compound semiconductor crystal containing As are 8n, 81. Although there are Ge, S, etc., S in particular is easily incorporated into the crystal by replacing the group 2 in the group 1-2 compound semiconductor. In particular, in the growth of a compound semiconductor containing human 3 as a V group, the amount of S incorporated is large, resulting in a high carrier concentration.

The present invention has the advantage that impurities are removed from the As-containing source gas by placing the crystal containing Mu3 in the decomposition region of the As-containing source gas, making the grown crystal highly purified and suppressing fluctuations due to the source gas slot.

According to this method, the pack ground concentration is
It can be reduced from Iα-3 to 5 x 10"c!r".

(Example of the invention) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

Fig. 1 shows a schematic configuration of a vapor phase growth apparatus used in an embodiment of the present invention.
I! ! J(b) is an enlarged cross-sectional view taken along the line A-A in FIG. 1(a), and FIG. 1(C) is an enlarged view of the vicinity of C in FIG. 1(a). In the figure, 1 is a reaction tube made of quartz glass or the like, and a reaction chamber within this reaction tube 1 is vertically symmetrically partitioned by a partition plate 2. An exhaust port 3 is provided near the right end of the reaction tube 1 . In addition, 4 is a sample subjected to vapor phase growth, and 5 is sample 4.
An operating rod 6° 7 is a resistance heating furnace for smoothly moving the material between the upper chamber 8 and the lower chamber 9. Note that the area heated by the heating furnace 6 (the area where the raw metal etc. are accommodated) is defined as a high temperature area, and the area heated by the heating furnace 7 (the area where the sample is accommodated) is defined as a low temperature area. The upper chamber 8 degrees and the left side (gas introduction side) of the lower chamber 9 contain gallium metal 10.1, which is a group ■ raw material.
2 and indium metal 11.13 are accommodated.

Carrier gas introduction pipes 14 to 17 for flowing hydrogen chloride gas into the metal are connected to the left end of the reaction tube 1, respectively. Also, upper chamber 8. Pipes 18 and 20 that flow V raw gas such as arsine and hoffin into each of the lower chambers 9
, H, S, etc. pipe 19.21
is connected. Near C, which is the high temperature decomposition region of the V group pipe 18.20, 5% GaAs polycrystalline is placed in a quartz boat.
The structure is such that the boat can be taken in and out from the left side of the introduction tube, and the GaAs polycrystals in the boat can be replaced one after another. The HCJ-gas to be supplied is A
Using pub'y-22, Z3 of sCj, A by decomposition death
The product produced by decomposing sCj3 was used. The temperature of the bubbler was set at 20℃ using a constant temperature bath, and the temperature of the decomposition furnace was set at 8℃.
The temperature was set at 50°C. The HC2 gas produced using this method has a higher purity than the HCJ-gas filled in commercially available cylinders. In which is 2° off from the (Zoo) plane
A case in which InGaAs is grown on a P substrate will be described below. The metal source temperature was set at 750°C to 900°C, and the growth temperature was set at 700°C. HCj flowing to In metal
10CC/+, Ga metal flowing HCJO09°c15
), 5 CCZ minutes of arsine, hydrogen carrier gas was used, and the total flow rate was 1.51/min. In addition, 0.5 cc/f+ of HCJ gas was added from the V group pipe to suppress precipitation on the pipe wall. 100% of the GaAs polycrystal is placed in the thermal decomposition region.
Then, the metal source temperature, that is, the temperature of the decomposition region where the GaAs crystal is placed, was varied from 750°C to 900°C. When the present invention is not used, the carrier concentration is 9×1
Although it varies from 0" to 3X10" due to differences in cylinder lots, when using the present invention, the carrier concentration becomes stable, and as the temperature of the decomposition region is raised, the carrier concentration decreases.
So, ~5×10m4cr! It becomes L. The obtained mobilities at room temperature and liquid nitrogen temperature were also 12,000, respectively.
""/y-see +96000cmR/v,. This shows that the crystallinity is also good. When we prototyped a PIN diode using this method, we found that the response speed was 1.
We were able to achieve 2GHz.

Next, a second example will be described. In a low-pressure MOCVD apparatus using a cracking furnace, 1509 GaAs polycrystals were placed in the cracking part.

The temperature of the cracking furnace is set to 850″ OK.TMI
Huff' Re-H270CC4 (17°O), T
MGO/<7'9/H.

1.35 ”4 (-10℃) AsH31G 5.H
t 10'4, growth temperature 620°C, pressure 200To
InGaAs was grown on a (100) InP substrate at rr. In the case where the present invention is not used, the carrier concentration of InGaAs fluctuates to about 5×10×3×10”α, whereas when the present invention is used, the carrier concentration is stabilized at around 2×10”. Easy movement at room temperature 77
tL sotL 10200crn”A1., ac,
42000””/y-see Te? ! 6'Q, although some compensation effect due to carbon etc. is observed, the crystallinity can be said to be good.

Note that the present invention is not limited to the above-mentioned practical example. In the above example, AsH@ was used as the group V growth gas and GaAs polycrystal was used to remove impurities, but when Ascus is used instead of AsH, and InGaAs, InAs, GaAsP, etc. is also valid. Furthermore, the growth material only needs to contain A3, such as InGaAsP or GaAsP with a composition of 1.55 pm instead of InGaAs.

It can also be applied to InAsP and the like.

〔Effect of the invention〕

According to the present invention, even if there are variations in the impurity level of the material gas containing As, the impurities are incorporated into As compound crystals in the decomposition region to purify the material gas.
High purity crystals containing s can be grown.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining an embodiment of the present invention, and Fig. 2 is a diagram showing the background of InGaAs and G when using the present invention.
FIG. 3 is a diagram showing the relationship with the temperature at which the aA1 crystal is placed. 1: reaction tube, 2: partition plate. 3: Outlet, 4: Sample. 5: Operation rod * 617: Resistance heating furnace. 8: Upper chamber, 9: Lower chamber. 1o, 12: gallium metal, 11.13
: Indium metal. 14-21: Introduction pipe + 22e 2-3:
ASCJ-s Know 2-1 Sae: Decomposition furnace, δ:
quartz boat. %: GaAs polycrystal. Agent Patent Attorney Noriyuki Chika Yudo Matsuyama Kosoku (C) Figure 1

Claims (6)

[Claims] (1) In a vapor phase growth method that includes a step of introducing a raw material gas containing arsenic and causing thermal decomposition, arsenic is contained as a Group V element in the passage of the raw material gas containing arsenic in the portion to be thermally decomposed.
A vapor phase growth apparatus characterized in that a III-V group compound semiconductor is installed. (2) The vapor phase growth apparatus according to claim 1, wherein the grown crystal is GaAs or InGaAs. (3) The vapor phase growth apparatus according to claim 1, wherein the source gas containing arsenic is AsH_2. (4) The III-V compound semiconductor containing arsenic is GaA
2. The vapor phase growth apparatus according to claim 1, wherein the vapor phase growth apparatus is s. (5) The vapor phase growth apparatus according to claim 1, wherein the growth method is a hydride vapor phase growth method. (6) The above-mentioned growth method is an MOCVD method having a preheating furnace for causing thermal decomposition or a pipe for causing thermal decomposition in a reaction tube. Phase growth device.