JPH04157716A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To reduce a deposit on an evacuation pipe and to enhance the operation rate of a vapor growth apparatus by a method wherein a protrusion part is formed at least either on the inner surface of an outer tube or on the outer surface of an inner tube. CONSTITUTION:At this vapor growth apparatus, its surface area is increased to about eight times by means of protrusion parts 15 formed on the surface of an outer tube 2. As a result, when an unreacted raw-material gas and a reaction by-product fall between an inner tube 4 and the outer tube 2, a deposit by the vapor-phase reaction of the raw-material gas and a deposit 14 by the reaction by-product are easily produced on the surface of the outer tube 2, and the raw-material gas and the reaction by-product are consumed much. As a result, the amount of the raw-material gas and the reaction by-product which flow into an evacuation pipe 11 becomes extremely small, and the deposit there is reduced sharply. As a result, the periodic cleaning frequency of the vapor growth apparatus is reduced sharply and its operation rate is enhanced sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vapor phase growth apparatus, and more particularly to a vertical reduced pressure vapor phase growth apparatus for forming a thin film on the surface of a semiconductor wafer.

[Conventional technology]

In recent years, vertical low pressure vapor phase growth apparatuses have been increasingly used to form thin films on the surfaces of semiconductor wafers. A cross-sectional view of an example of a conventional vertical reduced pressure vapor phase growth apparatus is shown in FIG.

The outside of the vapor phase growth reaction chamber 41 consists of a cylindrical quartz outer tube 42 with a closed upper end and a stainless steel stand 43 that supports it. Inside the reaction chamber 41, a cylindrical quartz inner tube 44 with both ends open is connected to the stainless steel base 4.
A quartz boat 45 is disposed inside the quartz boat 45, and a semiconductor wafer 46 is disposed horizontally on the quartz boat 45. The quartz boat 45 is supported by a stainless steel hatch 47 that can be moved up and down, and during vapor phase growth, the stainless steel hatch 47 is brought into close contact with the stainless steel stand 43, and the reaction chamber is sealed tightly. Further, a heater 48 is arranged outside the outer tube 42 to heat the inside of the reaction chamber 41. A gas introduction pipe 49 for supplying raw material gas is connected to the reaction chamber 41.
An exhaust port 50 is provided at the lower side of the outer tube 42 to communicate with the lower part of the inner tube 44 from the outside.
An exhaust pipe 51 is connected thereto and leads to a vacuum pump 53.

During vapor phase growth, the inside of the reaction chamber 41 is reduced in pressure by the vacuum pump 53, and the raw material gas is introduced into the inner tube 44 through the gas introduction tube 49, and as it ascends inside the inner tube 44 according to the arrow, the semiconductor wafer is heated through a vapor phase reaction. A thin film is formed on the surface of 46. Unreacted raw material gas and by-product gas generated by the gas phase reaction descend between the inner pipe 44 and the outer pipe 42 and reach the exhaust pipe 51.
The air is evacuated by a vacuum pump 53 through the air.

[Problem to be solved by the invention]

Generally, in vapor phase growth using this type of vertical vapor phase growth apparatus,
Not all of the raw material gas is consumed for vapor phase growth on the surface of the semiconductor wafer, and a large amount of unreacted raw material gas and byproducts from the vapor phase growth reaction flow between the inner and outer tubes. . Conventionally, the outer wall surface of the inner tube and the inner wall surface of the outer tube are flat and free of irregularities, so deposition due to the vapor growth reaction of the raw material gas and deposition of reaction byproducts between the outer tube and the inner tube rarely occur. Therefore, a large amount of unreacted raw material gas, by-products, etc. flow into the exhaust pipe, and as shown in FIG. 3, a large amount of deposits 54 are generated, which causes the exhaust pipe to become clogged. was there.

[Means to solve the problem]

The vapor phase growth apparatus of the present invention consists of a cylindrical outer tube with a closed upper end on the outside of the reaction chamber and a stand supporting the outer tube, and a cylindrical inner tube with both ends open inside the outer tube. is arranged on the table, a gas introduction pipe for introducing raw material gas into the inside of the inner pipe is provided, and a part of the outer pipe has a gas exhaust port,
In the vapor phase growth apparatus for forming a film on a semiconductor substrate placed inside the inner tube, a convex portion is provided on at least one of the inner surface of the outer tube or the outer surface of the inner tube.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of the invention.

As shown in FIG. 1, the outside of the reaction chamber 1 is composed of a cylindrical outer tube 2 made of quartz with a closed upper end and a stainless steel stand 3 on which the outer tube 2 is placed. The outer tube 2 has, for example, an inner diameter of 50 cm and a height of 100 cm at the side surface, and the inner surface has a width of 0.5 cm and a height except for the exhaust port 10 with an inner diameter of 1 provided at the bottom of the side surface. Sixty convex portions 15 each having a length of 11 cm are provided in a ring shape at 11 intervals. Inside this reaction chamber 1, an outer diameter 241 is opened at both ends.
．． Height 100C! A cylindrical inner tube 4 made of quartz is placed on a stainless steel backing 3.

Consider the surface area between the outer tube 2 and the inner tube 4. The sum of the surface areas of the inner surface of the side surface of the outer tube 2 and the outer surface of the side surface of the inner tube 4 is 23248 cal if there is no convex part 15, ignoring the exhaust port, but if the convex part 15 is provided, The surface area per part is 2695.5C11! Due to the increase, the entire convex portion increases by 161,729ctd to 187,977-. In other words, this convex portion increases the surface area by about eight times.

A quartz boat 5 is arranged inside the inner tube 4, and a semiconductor wafer 6 is arranged on the quartz boat 5. This quartz boat 5 is supported by a stainless steel hatch 7 that can be moved up and down, and during vapor phase growth, this stainless steel hatch 7 is closely attached to the stainless steel stand 3, so that the inside of the reaction chamber 1 is sealed tightly. Further, a heater 8 is arranged outside the outer tube 2, and a heater 8 is arranged outside the reaction chamber 1.
The inside of the is heated. Gas introduction pipe 9 for supplying raw material gas
is connected from the outside of the reaction chamber 1 to the lower part of the inside of the inner tube 4.

Further, an exhaust pipe 11 is connected to an exhaust port 1o at the lower side of the outer tube 2. The exhaust plumber 1 has a gate valve 12 and is connected to a vacuum pump 13.

During vapor phase growth, the inside of the reaction chamber 1 is reduced in pressure by the vacuum pump 13, and the raw material gas is introduced into the inner tube 4 from the gas introduction tube 9, and as it moves upward in the inner tube 4 according to the arrow, it is deposited on the surface of the semiconductor wafer 6. A thin film is deposited by a gas phase reaction. Unreacted raw material gas and gaseous reaction by-products generated by the gas phase reaction descend between the inner tube 4 and the outer tube 2 and are exhausted by the vacuum pump 13 through the exhaust pipe 11.

In the embodiment of the herb 1, the convex portion 15 provided on the surface of the outer tube 2
The surface area is approximately 8 times larger. Therefore, when the unreacted raw material gas and reaction by-products descend between the inner tube 4 and the outer tube 2, they are deposited on the surface of the outer tube 2 due to the gas phase reaction of the raw material gas, and the reaction by-products are deposited on the surface of the outer tube 2. Deposition 14 tends to occur, and much of the raw material gas and reaction by-products are consumed there. Therefore, the amount of raw material gas and reaction by-products flowing into the exhaust pipe 11 becomes extremely small, and the amount of deposition there is significantly reduced.

For example, ammonia (NH,il) dichlorosilane (S
A silicon nitride film (Si3
According to this embodiment, when forming N4), the unreacted raw material gas inside the inner tube 4 passes through the convex portion 15 of the outer tube 2 when descending between the inner tube 4 and the outer tube 2. Due to the increase in surface area, a gas phase reaction occurs that deposits silicon nitride on the surface, so much of the unreacted raw material gas is consumed there, and the amount flowing into the exhaust pipe is greatly reduced.

In addition, in this gas phase reaction, ammonium chloride (NH4CJ) is produced as a byproduct, but since most of this is deposited between the inner pipe 4 and the outer pipe 2, the amount deposited in the exhaust pipe 11 can be greatly reduced. can be reduced to In this case, by increasing the surface area of the outer tube 2 by eight times, the amount deposited in the exhaust pipe 11 will be about 115 times that of the conventional case. This has the advantage that the frequency of periodic cleaning of the serious vapor phase growth apparatus is greatly reduced, and the operating rate is greatly improved. FIG. 2 is a sectional view of a second embodiment of the invention.

In the example of Honso 2, the convex portions 35 are provided on both the inner wall surface of the outer tube 22 made of quartz and the outer wall surface of the inner tube 24 made of quartz. On the inner surface of the outer tube 22 with an inner diameter of 50 cIl,
There are 60 ring-shaped protrusions 35 with a thickness of 0.5 CII and a length of 60 m1, spaced at 1 cm intervals, and a ring-shaped protrusion 35 with a thickness of 0.5 CII and a length of 6 C1 l on the outer surface of the inner tube 24 with an outer diameter of 240 I. There are 60 pieces arranged at 1cm intervals. As a result, the surface area is 190 mm compared to 23248 mm without the convex portion 35.
632ad, an increase of approximately 8.2 times.

In the case of Example 2, gas molecules are more likely to hit the surfaces of the outer tube 22 and inner tube 24 than in the example of Weeding 1, in which the gas descends between the outer tube 22 and the inner tube 24. This tends to cause turbulence in the gas flow, so the outer tube 22
Accumulation is more likely to occur between the inner tube 24 and the inner tube 24. Therefore, the amount deposited on the exhaust pipe 31 can be further reduced.

〔Effect of the invention〕

As explained above, the present invention provides a vapor phase growth apparatus including:
By providing a convex portion on at least one of the inner wall surface of the quartz outer tube or the outer wall surface of the quartz inner tube, a convex portion is provided between the outer tube and the inner tube to prevent gas phase reaction of unreacted raw material gas passing therethrough. Deposition and deposition of gas phase reaction by-products can be effectively caused. Therefore, the amount of deposits in the exhaust pipe can be significantly reduced, resulting in the effect that the operating rate of the vapor phase growth apparatus can be significantly improved.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of first and second embodiments of the present invention, and FIG. 3 is a cross-sectional view of an example of a conventional vapor phase growth apparatus. 1.21.41...Reaction chamber, 2,22.42...Quartz outer tube, 3,23.43...Stainless steel stand, 4.
24.44... Quartz inner tube, 5, 25.45... Quartz boat, 6, 26.46... Semiconductor wafer, 7
．． 27.47...Stainless steel hatch, 8°28.4
8...Heater, 9,29.49...Gas introduction pipe,
10.30.50...Exhaust port, 11.31°51...
・Exhaust piping, 12, 32.52... Gate valve, 1
3.33.53...Vacuum pump, 54...Deposit,
15.35...Protrusion.

Claims (1)

[Claims] The outside of the reaction chamber is composed of a cylindrical outer tube with a closed upper end and a stand supporting this outer tube, a cylindrical inner tube with both ends open inside the outer tube is placed on the stand, and the A gas introduction pipe for introducing raw material gas into the inner pipe is provided, a gas exhaust port is provided in a part of the outer pipe, and a gas phase is provided to form a film on a semiconductor substrate disposed inside the inner pipe. A vapor phase growth apparatus characterized in that a convex portion is provided on at least one of the inner surface of the outer tube or the outer surface of the inner tube.