JPS58132921A - Vapor phase growth method - Google Patents

Abstract

PURPOSE:To quickly form an excellent epitaxial grown layer of InP series by mixing gases in the neighborhood of a substrate for growing in the compound semiconductor growth method. CONSTITUTION:A gas supply tube 13 for organic metal such as TEI is used to supply gas to a furnace core tube 1, whereas a gas tube 14 positioned outside the gas supply tube 13 is employed to lead PH3, etc. to a gas mixing apparatus 15. TEI is mixed with PH3 in the region 16 located at the edge of the substrate of the gas mixing apparatus 15. A high frequency heating coil 17 is mounted in the region covering a substrate 9, a susceptor 8 and the gas mixing apparatus 15. PH3 introduced in a heated condition at high temperatures through the gas supply tube 14 is thermally decomposed in the region 18 belonging to the gas mixing apparatus 18 and decomposed P and In of TEI react on each other in the region 16, so that InP is formed on the substrate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vapor phase growth apparatus capable of producing a good growth layer of a compound semiconductor.

Epitaxial growth methods for I-■ compound semiconductors include a liquid phase growth method and a vapor phase growth method, and the vapor phase growth method is suitable for mass production. In particular, the MOCVD method (which allows the gas phase ratio and solid phase ratio to be approximately equal and has superior controllability compared to the halide method)
MetaJ-Organic-CVD).

FIG. 1 shows the conventional MOCVD method. In the figure, end caps 2.3 are provided at both ends of the furnace core tube 1,
The end cap 2 is provided with a gas supply pipe 4.6.

For example, when growing InP crystals, T is used as the organic metal.
EI() ethyl indium) to the gas supply pipe 4, PH
3 gases are supplied to the furnace core tube independently from the gas supply W6.

The gas flowing out of the furnace core tube is exhausted from the outlet 6. The susceptor 8 on the port 7 is made of graphite coated with SiC, and the substrate 9 is placed on it to detect the susceptor 8 and normally apply feedback to control the temperature at a constant temperature. For example, when performing epitaxial growth of InP on an InP substrate with this equipment, the amount of TEI transported, the amount of PH3 transported,
Even when the growth temperature is changed, the growth rate is extremely slow.

For example, place TEI in a constant temperature bath at 65°C, and
bubbling with H2 in, and pH 32% H2 pace gas 200 (L/min) with 117 m1N H2
Transported with carrier gas, 90m1 at growth temperature 660℃
An epitaxial layer of InP with a thickness of about 0.1 μm is formed on the substrate 9 by the n treatment.

However, this method has a slow growth rate and is not practical. The reason for this slow growth rate is that the decomposition of PH3 is not successful, and PH3 reacts with TEI, resulting in (C2H5)3 and PH3.
This is because Comp l ex is formed to inhibit InP growth. Therefore, there is a method in which a heating furnace 12 is provided in the gas supply pipe 6, which is a PH3 gas line, and heated to about 700° C. to promote decomposition of PH3.

This method improves the growth rate a little, but there is growth of InP in areas other than the substrate 7i, and there is a loss in the region where TEI reacts with In (indium). Also, if the heating furnace 12 and the furnace core tube 1 of the reaction furnace are not placed close to each other, the gas supply tube 5 between them
P adheres to the tube wall, resulting in poor efficiency. Furthermore, in this case, the region of the gas supply pipe 6 in the heating furnace 12 must be made of quartz, which tends to make the apparatus complicated.

In view of the above points, the present invention aims to provide a vapor phase growth method in which gases are mixed near the growth substrate and a good InP-based epitaxial growth layer can be formed quickly. FIG. 2 shows an embodiment according to the present invention.

In the figure, the same numbers as in FIG. 1 indicate the same parts, and the gas supply to the furnace core tube 1 is performed using the gas supply pipe 13 for organic metals such as TEI, and the gas supply pipe 13 is used for PH3 etc. outside the gas supply pipe 13. The gas is introduced into the gas mixing device 15 using the gas supply pipe 14, and TEI and PH3 are mixed in a region 16 at the substrate side end of the gas mixing device 150. If the gas mixing device 16 is, for example, in the shape of a coaxial cylindrical carbon block with a hollow space, the gas supply pipe 13 is installed across the inner wall thereof. When the high-frequency heating coil 17 is placed in a region covering the substrate 9, susceptor 8, and gas mixer 16, fCPH3 is introduced via the gas supply pipe 14 in a high-temperature heating state and is thermally decomposed and decomposed in the region 18 inside the gas mixer. P and I of TEI
n reacts in the region 16 to form KInP on the substrate 9.

Note that the mixing state of the reaction gas is important for the uniformity of the film thickness of the InP growth layer grown on the substrate 9, and the gas mi! A quartz block or carbon block for lnq may be installed. Further, it is desirable to keep the inner wall of the gas mixing device 15 and the gas supply pipe 13 such as TEL sufficiently apart. If you don't do this,
TEI and the like are thermally decomposed by the heat from the gas mixing device 16 and adhere in the form of In to the pipe wall of the region 18 in the gas mixing device 15 of the gas supply pipe 13, slowing down the growth rate of InP on the substrate 9. Become. Therefore, it is desirable to provide a sufficient distance between the inner wall of tube 16 and tube 13, or to cool the tube 13 by increasing the flow rate of PH3 and TEI, for example. Further, it is preferable that the collision angle between the reaction gas and the substrate 9 be close to 900, and that the carbon block 19 be placed on the susceptor 8.

FIG. 3 shows another embodiment of the invention. The same numbers as in FIG. 1 indicate the same items. For organometallic systems such as TEI, use gas supply pipe 2.
For PH3 and the like, a gas supply pipe 21 is used. The difference from the embodiment of FIG. 2 is that the gas mixing device 22 is made of quartz. However, the region 23 is shaped like a trumpet to efficiently transfer the PH3 etc. introduced from the gas supply pipe 21 to the substrate 9.
k so as to supply the surrounding area. Note that the shape of the region 23 may be any shape as long as it can collect and mix gas in terms of efficiency.

TEI and PH3 are mixed in the region 24 of the gas mixing device 22.
xing and transported onto the substrate 9. The uniformity of the film thickness and film quality on the substrate 9 are determined by the collision angle between the substrate 9 and the reaction gas, the diameter of the cylindrical gas mixing device 22, the flow rate and concentration ratio of TEI and PH3, and the like. To improve mixing, a quartz block, a block, or a carbon block for mLxincl may be placed in the area 24. The high frequency heating coil 25 is placed in the area 24, which covers the susceptor 8.

An example of the growth conditions in the present invention shown in FIG. 3 is, for example, PH34c.
t-/rnxn, T EIO bubbling H2
1o0ec/min, T E I 65℃, T
OTAL H24g/min.

If the growth temperature is 650℃, InP of about 1μm/hr
An epitaxial layer was obtained that was substantially uniform over the entire area of the 8x12fi sized substrate. The obtained epitaxial layer was in a non-doped state with P at room temperature.
Half width of L (photoluminescence) is 30 nm, key y rear concentration 2 x 1016 cm-3, mobility 3000
A good growth layer of cn/V-SeC was obtained.

As is clear from the above facts and flows, by improving the mixing of TEI and PH3, good In
It is possible to quickly form a P epitaxial layer, and since the gas mixing device, gas supply pipe, susceptor, etc. are removable, the inside of the pipe can be easily cleaned.

In the above embodiments, InP-based vapor phase growth was described, but the present invention also applies to epitaxial growth of other compound semiconductor layers that have a reaction process similar to that of InP-based materials, such as P (IJn), and other thermal growth methods. As described above for the formation of compound semiconductors using gases with poor decomposition properties, the present invention has a simple structure, is relatively quick, and can form high-quality epitaxial growth layers. It is suitable for mass production of growth layer formation and has high industrial value.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional vapor phase growth apparatus, and FIG. 2 is a schematic diagram of a conventional vapor phase growth apparatus. FIG. 3 shows a schematic diagram of a vapor phase growth apparatus used in an embodiment of the present invention. 1... Furnace core tube, 7.・・・－・・・Boat, 8・
... Susceptor, 9o... Substrate, 17, 25.
・・＠・−High frequency heating coil, 13, 20・・−
--T E I supply pipe, 1421...-IIPH3
Supply pipe, 15, 22 · · · Gas mixing device.

Claims (3)

[Claims] (1) A substrate is placed on the downstream side of a gas mixing device in a crystal growth furnace core tube, a reaction gas is supplied from the upstream end of the gas mixing device, and a reaction gas is supplied from the downstream end of the gas mixing device. A vapor phase growth method characterized by forming a compound semiconductor layer on a substrate by supplying an organometallic gas nearby. (2) The vapor phase growth method according to claim 1, wherein part or all of the gas mixing device is made of carbon. (3) The gas mixing device has the same cylindrical shape, and the organometallic gas is placed on the inside and the reactive gas (4), which has poor thermal decomposition properties, is placed on the outside.
) The vapor phase growth method according to claim 1, characterized in that PH3 is used as the reaction gas.