JPH08310896A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE: To provide a vapor growth apparatus which is improved in the working rate at the time of mass production. CONSTITUTION: This vapor growth apparatus has a reaction vessel 1 which is formed to a cylindrical shape and internally has a susceptor held at a shaft 10 and a discharge section 20 which discharges the gases in this reaction vessel 1 to the downstream of the susceptor in the reaction vessel 1. This discharge section 20 is mounted with an exhaust ring 21 coaxial with the shaft 10. The discharge section 20 is provided with a take-out port 23 in such a manner that this exhaust ring 21 is made removable outside the discharge section 20. The exhaust ring 21 is mounted at the discharge section 20 removably from the discharge section 20 in a perpendicular direction to the shaft from the take-out port 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vapor phase growth apparatus, and more particularly to a vapor phase growth apparatus having a barrel type susceptor in a reaction vessel for performing a vapor phase growth of a compound semiconductor thin film.

[0002]

2. Description of the Related Art The principle of growing a compound semiconductor thin film by a metal organic chemical vapor deposition (MOCVD) method is as follows. That is, for example, an organic metal such as trimethylgallium (TMG) or trimethylaluminum (TMA) as a raw material of gallium (Ga) or aluminum (Al) is supplied together with a carrier gas such as hydrogen gas into a reaction furnace, and arsenic (As) is supplied. And arsine (AsH ₃ ) as a raw material for phosphorus (P)
Or phosphine (PH ₃ ) hydride gas is used, and silicon (Si) and lead (Zn) are supplied as impurities using silane (SiH ₄ ) or trimethylzinc (TMZn). Then, by subjecting these gases to thermal decomposition reaction in the reaction furnace, a desired composition (GaAs, GaAs, InP, etc.) is formed on the heated compound semiconductor substrate (GaAs, InP, etc.).
InP, InGaAs, AlGaAs, etc.), film thickness and carrier density (n-type, p-type) are deposited.

In the vapor phase growth apparatus for performing such growth, as a device for processing a large number of semiconductor substrates (wafers) in a single process, a susceptor for mounting the substrates is formed in a polygonal cone shape. (Generally called barrel type susceptor),
A device for mounting substrates on each surface thereof is often used as a mass production device.

A conventional vapor phase growth apparatus has a structure as shown in FIG. 5, for example. In the figure, reference numeral 2 is a gas inlet provided at the top of a cylindrical quartz glass reaction vessel 1 constituting the vapor phase growth apparatus for introducing a mixed gas of a raw material gas and a carrier gas. Reference numeral 3 is an exhaust portion for the carrier gas and unreacted raw material gas provided at the bottom of the reaction vessel 1, and 3a is an exhaust port. Reference numeral 4 denotes a carbon susceptor provided inside the reaction vessel 1 and has a polygonal cone shape. A compound semiconductor substrate 5 on which a thin film is to be grown is placed on the side surface of the susceptor 4. Reference numeral 6 is a high frequency induction coil provided on the outer periphery of the reaction vessel 1. The high-frequency induction heating by the high-frequency induction coil 6 heats the raw material gas to 600 to 700 ° C. to cause a thermal decomposition reaction to grow a compound semiconductor thin film on the compound semiconductor substrate 5. 7 is a cooling jacket provided in the reaction vessel 1, 8
Is a cooling water inlet, and 9 is a cooling water outlet. A shaft 10 holds the susceptor 4 and rotates the susceptor 4. Reference numeral 11 is a front chamber, and 12 is a gate valve that opens and closes between the reaction container 1 side and the front chamber 11. Reference numeral 13 is a gas inlet, and 14 is a substrate outlet.

When a GaAs thin film is deposited using trimethylgallium and arsine using this vapor phase growth apparatus, a reaction of Ga (CH ₃ ) ₃ + AsH ₃ → GaAs + 3CH ₄ occurs. At this time, arsine is used as trimethyl in order to prevent thermal decomposition of arsine at the temperature in the reaction vessel 1, to prevent sublimation of arsenic from the GaAs crystal, and to prevent carbon from being taken into the crystal. It is general to supply in excess (10 to 100 times) with respect to gallium. This means that InGaAs is A
The same applies to the case of depositing 1GaAs or the like. After depositing the compound semiconductor thin film on the compound semiconductor substrate 5 in this manner, the carrier gas and the unreacted source gas are exhausted from the exhaust port 3a.

By the way, during the thermal decomposition, arsine and phosphine are decomposed, and only a part thereof contributes to the formation of a semiconductor thin film deposited on the substrate, and the remaining vaporized arsenic is exhausted to the outside of the reaction vessel 1. Be led to. At this time, since the exhaust gas is cooled from the temperature of the reaction container 1 (600 to 700 ° C.) to about room temperature, arsenic and phosphorus are solidified in the form of powder or fragments, and the exhaust pipe or valve (valve) is solidified. ) Will be blocked. Therefore, in the vicinity of the exhaust port 3a where the gas is most cooled, a large surface area, for example, 3
Shaft 1 with a quadruple pipe (called an exhaust ring)
It is often the case that the gas passages are provided coaxially with 0 and a plurality of gas passages are provided, and most of the solidified matter is attached at this portion to prevent subsequent gas pipes and valves from being clogged with the solidified matter. The exhaust string 15 is, for example, as shown in FIG.
As shown in (b), a cylinder 15 having a plurality of holes 15b
a is installed concentrically with the position of the hole 15b being shifted.

[0007] Since the side surface of the susceptor 4 is installed at a very steep angle (1 to 20 ° with respect to the vertical direction), the mounting and removal of the substrate 5 to and from the barrel type susceptor 4 are mostly performed manually. Therefore, the susceptor 4 and the inner wall of the reaction container 1 are exposed to the atmosphere. By the way, on the inner wall of the reaction vessel 1,
Since the powdery solidified substance is attached and the surface area is large, when the atmosphere comes into contact with the solidified substance, oxygen and water which have a great influence on the purity of the thin film semiconductor crystal are adsorbed. Therefore, in order to prevent this adsorption, the front chamber 1 in which the substrate 5 is mounted / demounted
1 is provided. Then, when the substrate 5 is attached or detached, the susceptor 4 is moved to the front chamber 11 by the vertical movement of the shaft 10 holding the susceptor 4, and the front chamber 11 and the reaction container 1 are moved by the gate valve 12 or the like. Cut off. By doing so, it is possible to prevent the reaction container 1 part from being exposed to the atmosphere. After mounting / demounting the substrate 5, gas purging with high-purity hydrogen or the like is performed in the antechamber 11, the gate valve 12 is opened, and the susceptor 4 is raised in the reaction container 1 to increase the purity of the grown semiconductor thin film. To maintain.

[0008]

As described above, by providing the exhaust ring, it is possible to prevent the exhaust pipe from being clogged with the reaction products and the solidified products such as the decomposed arsenic or phosphorus powder of the unreacted source gas. Can be prevented. However, since the exhaust ring itself is blocked,
It is necessary to exchange the exhaust ring after every thin film growth. When exchanging the exhaust ring, it is necessary to remove the large reaction vessel, carefully reassemble the reaction vessel and adjust it, and set the growth conditions for the thin film. There is a problem that it takes time and the operation rate of the device is lowered. The uniformity of the compound semiconductor thin film to be produced, the carrier density, and the like within the substrate surface and between the substrates placed on each side surface of the susceptor are determined by the shape and installation angle of the susceptor, the flow rate of the gas flowing into the reaction vessel. In addition to (the sum of the raw material gas and the carrier gas), the relative positional relationship between the susceptor and the inner wall of the reaction vessel is also influenced. Therefore, as described above, the assembling work of the reaction container requires careful adjustment.

[0009]

SUMMARY OF THE INVENTION The present invention provides a vapor phase growth apparatus which solves the above problems. The invention of claim 1 has a tubular shape and has a susceptor held by a shaft therein. In a vapor phase growth apparatus in which a reaction container and an exhaust part for exhausting gas in the reaction container are provided downstream of a susceptor in the reaction container, and an exhaust ring is attached to the exhaust part coaxially with the shaft, the exhaust part Is characterized in that an outlet is provided so that the exhaust ring can be detached from the exhaust portion.

According to a second aspect of the present invention, in the first aspect of the present invention, an exhaust pipe is provided in the exhaust section for avoiding the exhaust port of the exhaust ring to exhaust the gas in the reaction vessel. It has a pipe part, and the straight pipe part has a double pipe structure in which an auxiliary straight pipe is inserted thereinto so as to be detachably attached, and gas mainly passes through the auxiliary straight pipe. To do.

Here, the exhaust ring is, as described in the prior art, a hole formed in a concentric multiple tubular body, which is installed in front of the exhaust port and serves as a baffle plate for the exhaust gas. It effectively removes the reaction product and effectively attaches the reaction product.

[0012]

In the invention of claim 1, since the exhaust portion is provided with an outlet for removing the exhaust ring mounted therein to the outside of the exhaust portion, the exhaust ring can be replaced without removing the reaction container. Can be cleaned. Therefore, the exhaust ring replacement and cleaning work time is shortened, and the operating rate of the apparatus is improved. Further, in the invention of claim 2, the exhaust pipe provided in the exhaust portion has a straight pipe portion, and the straight pipe portion is detachably attached by inserting an auxiliary straight pipe therein, and the gas is mainly the auxiliary straight pipe. Since it has a double tube structure that passes through the tube, solidified products such as reaction products mainly adhere to the inner auxiliary straight tube. Therefore, only the inner auxiliary straight pipe is removed and replaced,
Alternatively, cleaning may be performed, which facilitates the cleaning work of the exhaust pipe and shortens the working time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. Example 1. FIG. 1 is an explanatory diagram of an embodiment of a vapor phase growth apparatus according to the present invention. The reference numerals in the figure are the same as those in FIG. Reference numeral 20 is an exhaust unit. Further, FIGS. 2A and 2B are a detailed partial vertical cross-sectional view and a cross-sectional view taken along line AA of the exhaust unit 20 of the present embodiment, respectively. An exhaust port 20a is provided in the exhaust unit 20, and an exhaust ring 21 is arranged inside the exhaust port coaxially with the shaft 10 holding a susceptor. The exhaust ring 21 is composed of quintuple tubes 21a to 21e, and each tube is provided with a hole. Outermost tube 21
The hole 22a of a is located facing the exhaust port 20a. Further, the other tubes 21b to 21e are respectively provided with four holes 22b to 22e at a central angle of 90 °, and the holes 22a to 22e of the adjacent tubes 21a to 21e are displaced at a central angle of 45 °. Are arranged concentrically. Further, the exhaust portion 20 is provided with a take-out port 23 for the exhaust ring 21 on the opposite side of the exhaust port 20a, and a flange 24
It is hermetically sealed by. This outlet 23 is
The exhaust ring 20 has a width substantially equal to the outer diameter of the exhaust part 20 and a size that allows the exhaust ring 21 to pass through.

The removal and mounting of the exhaust ring 21 are performed as follows. 1) In FIG. 1, by lowering the shaft 10 of the susceptor 4, the susceptor 4 is lowered from the reaction container 1 into the front chamber 11 and the gate valve 12 is closed. 2) Next, as shown in FIGS. 2A and 2B, the flange 24 that seals the outlet 23 of the exhaust unit 20 is removed. 3) Next, take out the exhaust ring 21 and the outlet 23.
From the shaft 10 in a direction perpendicular to the shaft 10 (horizontal direction). 4) When mounting the exhaust ring 21 from which the reaction product has been removed, first, the exhaust ring 21 is put into the exhaust section 20 from the outlet 23 in reverse. 5) Next, the outlet 23 is hermetically sealed with the flange 24. 6) Next, the gate valve 12 is opened and the shaft 10
By raising, the susceptor 4 is raised from the front chamber 11 into the reaction container 1.

In the apparatus of the present embodiment, the replacement of the exhaust ring and the work of purifying the reaction container (drying the reaction container) for 4 hours are all required, and the growth conditions are not set again. I was able to return to the original manufacturing process. By the way, in the conventional method, the reaction vessel is disassembled, the exhaust ring is taken out and replaced, and it is assembled again for 10 hours, and further for 24 hours or more for the growth condition determination of the compound compound semiconductor thin film in that state (for thin film evaluation. It took time).

In the above embodiment, as can be seen from FIG. 2 (b), the outlet port 23 side of the exhaust part 20 protrudes by the width of the outer diameter, and the exhaust ring 21 and the flange 24 are provided.
An arcuate space 25 is created between the two. When the reaction container is evacuated through the exhaust port 20a, the space 25 is closed by the exhaust ring 21 and becomes a dead space, which makes exhausting difficult. Therefore, if the shape of the flange 24 is an arcuate shape on the inner side 24a as shown in FIG.
When the flange 24 is attached to the take-out port 23, the space 25 is substantially closed, and the rate of increase in the degree of vacuum when the reaction container 1 is evacuated is increased.

FIG. 4 is a sectional view of another embodiment of the exhaust unit 20. In this embodiment, the exhaust ports 29 are provided on both sides of the exhaust ring 21 while avoiding the extraction port 23. The exhaust pipe 30 attached by bypassing the exhaust port 29 has a straight pipe portion 31, and straight pipes 32, 33 having a circular cross section.
Are crossed at 90 °, and the gas from the exhaust ports 29 on both sides is collected at one location and discharged from the intermediate portion of the straight pipe 33. In the straight pipes 32 and 33, auxiliary straight pipes 32a and 33a having a circular cross section are detachably inserted. The outer diameters of the auxiliary straight pipes 32a and 33a are smaller than the inner diameters of the straight pipes 32 and 33, respectively, but have sizes close to these inner diameters. By doing so, most of the exhaust gas will pass through the auxiliary straight pipes 32a and 33a. To assemble the exhaust pipe 30, the auxiliary straight pipe 33a is attached to the flange 35.
Removed and inserted into the straight pipe 33, and then the auxiliary straight pipe 32
a is performed by removing the flange 34 and inserting it into the straight pipe 32.

In the exhaust pipe 30, the auxiliary straight pipe 32a,
Since the reaction product mainly adheres to the inside of the exhaust pipe 33a, when the exhaust pipe is blocked, only the auxiliary straight pipes 32a and 33a need to be taken out and replaced, which shortens the cleaning time of the exhaust pipe 30. Further, conventionally, since the exhaust pipe was cleaned while being attached to the device (for example, using a vacuum cleaner), there was a risk that the worker was exposed to harmful substances. This risk is reduced if only the cleaning device is cleaned.

In the present invention, the structure of the exhaust ring is not limited to the above embodiment.

[0020]

As described above, according to the first aspect of the present invention, a reaction vessel having a tubular shape and having a susceptor held by a shaft therein, and a reaction vessel inside the reaction vessel downstream of the susceptor in the reaction vessel. In the vapor phase growth apparatus having an exhaust part for exhausting the gas, the exhaust part being fitted with an exhaust ring coaxially with the shaft, the exhaust part can be detached from the exhaust part to the outside of the exhaust part. Since the outlet is provided, there is an excellent effect that the exchange time of the exhaust ring and the cleaning work time are shortened and the operation rate of the apparatus is improved. Further, according to the invention of claim 2, an exhaust pipe for exhausting gas in the reaction container is provided in the exhaust part while avoiding the exhaust port of the exhaust ring, and the exhaust pipe has a straight pipe part. The pipe part has a double pipe structure in which an auxiliary straight pipe is inserted and detachably attached, and the gas mainly passes through the auxiliary straight pipe, which facilitates the cleaning work of the exhaust pipe, This has the effect of shortening the work time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a vapor phase growth apparatus according to the present invention.

2 (a) and 2 (b) are a partial vertical cross-sectional view and an AA cross-sectional view of an embodiment of an exhaust unit in the above embodiment, respectively.

FIG. 3 is a cross-sectional view of another embodiment of the exhaust unit.

FIG. 4 is a cross-sectional view of yet another embodiment of the exhaust unit.

FIG. 5 is an explanatory diagram of a conventional vapor phase growth apparatus.

6A and 6B are a vertical cross-sectional view and a cross-sectional view taken along line AA of a conventional exhaust portion, respectively.

[Explanation of symbols]

 1 Reaction Container 2 Gas Inlet 4 Susceptor 5 Compound Semiconductor Substrate 6 High Frequency Induction Coil 7 Cooling Jacket 8 Cooling Water Inlet 9 Cooling Water Outlet 10 Shaft 11 Front Chamber 12 Gate Valve 13 Gas Inlet 14 Outlet 20 Exhaust 20a Exhaust 21 Exhaust ring 21a to 21e Pipe 22a to 22e Hole 23 Outlet port 24 Flange 24a Inside 25 Space 29 Exhaust port 30 Exhaust pipe 31 Straight pipe part 32, 33 Straight pipe 32a, 33a Auxiliary straight pipe 34, 35 Flange

Claims (2)

[Claims] 1. A reaction container having a tubular shape and having a susceptor held by a shaft therein, and an exhaust unit for exhausting gas in the reaction container downstream of the susceptor in the reaction container. In the vapor phase growth apparatus in which an exhaust ring is mounted coaxially with the shaft, the exhaust unit is provided with an outlet for detaching the exhaust ring from the exhaust unit. . 2. The exhaust part is provided with an exhaust pipe for exhausting the gas in the reaction container while avoiding the exhaust ring outlet, and the exhaust pipe has a straight pipe part, and the straight pipe part is provided inside the exhaust pipe. 2. The vapor phase growth apparatus according to claim 1, wherein the auxiliary straight pipe is inserted and removably attached, and the gas has a double pipe structure in which the gas mainly passes through the auxiliary straight pipe.