JP3098093B2 - Chemical vapor deposition equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer processing apparatus used in a semiconductor manufacturing process, and more particularly to a chemical vapor deposition apparatus (hereinafter referred to as a "CVD apparatus") for forming a silicon oxide film, a silicon nitride film and the like on a wafer. ").

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a cross-sectional view showing a conventional CVD apparatus disclosed in Japanese Patent Application Laid-Open Publication No. H10-15095. In the figure, 1 is a wafer, 2 is a quartz board on which the wafer is mounted, 3 is a reaction tube, 4 is a front cap for sealing the reaction tube 3, 5 is a heater for heating the wafer, and 6 is a reaction tube 3 A gas inlet for introducing a reaction gas and an inert gas into the inside, 7 is a gas exhaust port for exhausting the reacted gas and the inert gas, 8 is a valve provided on an exhaust pipe, and 9 is a symbol. It is a vacuum pump that operates constantly and exhausts the pressure inside the reaction tube 3 under reduced pressure.

In such a configuration, for example, the wafer 1 is placed on the quartz board 2 and carried into the reaction tube 3, and the front cap 4 is closed to seal the reaction tube 3. Then,
The heater 5 heats the inside of the reaction tube 3 and the loaded wafer 1 to a constant temperature. Subsequently, the valve 8 is opened, and the exhaust port 7 is opened.
Further, the inside of the reaction tube 3 is evacuated and evacuated by the vacuum pump 9.
Thereafter, a reaction gas is introduced into the reaction tube 3 from the gas inlet 6. The reaction gas introduced into the reaction tube 3 is supplied to the gas inlet 6
It is further diffused and distributed in the direction of the gas exhaust port 7, decomposed by a thermochemical reaction, and a desired thin film is grown on the wafer 1.

Next, the introduction of the reaction gas is stopped, the inside of the reaction tube 3 is evacuated again, and the valve 8 is closed. Then, an inert gas is introduced into the reaction tube 3 from the gas inlet 6. Then, the inside of the reaction tube 3 is returned to the atmospheric pressure. Then, the front cap 4 is opened, and the quartz board 2 on which the wafer 1 is placed is placed.
Unloaded, close the front cap 4 and add a new wafer 1
Wait for carry-in.

FIG. 3 is a sectional view showing a conventional CDV apparatus disclosed in Japanese Patent Publication No. 2-41166. In the figure, 1, 2, 4, 6, and 7 are exactly the same as those of the conventional CVD apparatus, but the reaction tube 3 has a first reaction tube 3A having a number of small holes, and the first reaction tube 3A And a second reaction tube 3B installed outside the tube. In addition, a gas exhaust port 7A is provided at an end of the first reaction tube 3A, and a space 10 between the first reaction tube 3A and the second reaction tube 3B is exhausted at an end of the second reaction tube 3B. Gas exhaust port 7B is provided.

In such a configuration, the quartz board 2 on which the wafer 1 is mounted is loaded into the reaction tube 3A, and the inside of the reaction tube 3 and the loaded wafer 1 are heated to a constant temperature by the heater 5, and then, The space 10 from the gas exhaust port 7B
Exhaust. Thereafter, the first and second reaction tubes 3A and 3B are evacuated and evacuated from the gas exhaust port 7A.
By introducing a reaction gas from the gas inlet 6 into the inside,
A desired thin film is grown on the wafer 1.

Subsequently, the introduction of the reaction gas is stopped, the inside of the first reaction tube 3A is evacuated again, and all valves of the exhaust pipe are closed. Then, by introducing an inert gas into the first reaction tube 3A and the second reaction tube 3B from the gas inlet 6, the first reaction tube 3A and the second reaction tube 3A are introduced.
The inside of B is returned to the atmospheric pressure. Then, the front cap 4 is opened, the quartz board 2 on which the wafer 1 is mounted is taken out, the front cap 4 is closed again, and a new wafer 1 is loaded.

[0008]

The conventional CDV apparatus is constructed as described above.
The reaction product easily adheres to the inner wall of the gas, the peripheral portion of the gas exhaust port 7 and the exhaust pipe between the gas exhaust port 7 and the valve 8,
In particular, the reaction products are extremely attached to the peripheral portion of the gas exhaust port 7 having a low temperature and the exhaust pipe between the gas exhaust port 7 and the valve 8, and the form is an aggregate of fine particles. For this reason,
The deposit is peeled off and moves onto the wafer 1 in the reaction tube 3,
There is a problem in that it adheres and forms foreign particles, deteriorating the film quality of the wafer and hindering improvement in the manufacturing yield of semiconductor devices.

In the conventional CVD apparatus shown in FIG.
Although the space 10 between the first reaction tube 3A and the second reaction tube 3B is evacuated, a preventive measure is taken to remove the deposits adhering to the inner wall of the first reaction tube 3A. There has been a problem that a sufficient effect cannot be expected for removing adhering substances to the peripheral portion and the exhaust pipe between the gas exhaust port 7B and the valve 8. Conversely, the deposits adhering to the peripheral portion of the gas exhaust port 7B and the exhaust pipe between the gas exhaust port 7B and the valve 8 are peeled off, and the gas flows when the space of the reaction tube 3 is eliminated, so that the gas flows onto the wafer 1. In some cases, they adhered to form foreign matter.

[0010]

In a CVD apparatus according to the present invention, a large flow gas control device is provided in a gas supply system, and a branch pipe is connected to an exhaust pipe system and connected to a branch pipe.
And the pressure inside the reaction tube and the exhaust piping system is lower than atmospheric pressure.
An ejector vacuum pump is provided to maintain a vacuum of from to several hundred Torr .

[0011]

In the CVD apparatus according to the present invention, the deposits adhering to the inside of the exhaust pipe and adhering to the reaction tube after being separated from the exhaust pipe and serving as nuclei of the foreign matter on the wafer,
The gas is supplied into the reaction tube from the large flow gas control device, and is purged by the resistance of the flow of an inert gas such as nitrogen gas exhausted by an ejector type vacuum pump.

Further, by maintaining the pressure inside the reaction tube and the inside of the exhaust pipe at a low vacuum of less than atmospheric pressure to several hundred torr, the amount of heat conducted from the reaction tube to the exhaust pipe system increases, and the exhaust pipe system has By increasing the temperature, the deposits attached to the exhaust pipe system change to a property that does not easily peel off, and the pressure inside the reaction tube and the exhaust pipe is maintained at a low vacuum of less than atmospheric pressure to several hundred Torr. The temperature change of the exhaust piping system when the state is shifted from the state in which the wafer is returned to the atmospheric pressure in which the wafer is carried into the reaction tube is reduced, and the separation of the deposits due to the thermal cycle is significantly suppressed.

[0013]

FIG. 1 is a sectional view of a chemical vapor deposition apparatus showing one embodiment of the present invention. In FIG. 1, a reaction tube 3, a front cap 4, a heater 5, a gas inlet 6, a gas outlet 7, Since the valve 8 and the vacuum pump 9 are exactly the same as those in the conventional example, only reference numerals are given and the description is omitted.

Reference numeral 11 denotes a large flow gas control device provided in a gas supply system including the gas inlet 6, reference numeral 12 denotes a branch pipe provided in an exhaust pipe system, and reference numeral 13 denotes a branch pipe 12
Is an ejector type vacuum pump connected to. In such a configuration, before loading the quartz board 2 on which the wafer 1 is mounted into the reaction tube 3, the valve 8 of the gas exhaust system is closed, and the inert gas such as nitrogen gas is purged by the large flow gas control device 11. The gas is introduced into the reaction tube 3 through the gas inlet 6 and evacuated by the ejector type vacuum pump 13 through the branch pipe 12 .

At this time, when the exhaust capacity of the ejector type vacuum pump 12 is controlled to maintain the pressure inside the reaction tube 3 and the exhaust pipe at a low vacuum of less than atmospheric pressure to several hundred Torr, the exhaust gas from the reaction tube 3 is exhausted. The amount of heat that conducts gas to the piping system increases, the temperature of the exhaust piping system in which the deposits are generated is increased, and the deposits change to a property that is not easily separated.

[0016]

As described above, according to the present invention, the foreign matter on the wafer, which adheres to the inner wall of the exhaust pipe and the like which is a nucleus of the foreign matter on the wafer, is separated from the exhaust pipe and moved to the reaction tube side. The kimono is supplied with the inert gas from the large flow gas control device into the reaction tube and exhausted by the ejector type vacuum pump, so that the kimono has an effect of being wiped out by the resistance of the flow of the inert gas.

Further, by maintaining the pressure inside the reaction tube and the exhaust pipe at a low vacuum of less than atmospheric pressure to several hundred torr, the amount of heat conducted from the reaction pipe to the exhaust pipe system increases, and deposits are formed. As the temperature of the exhaust pipe system was increased, the deposits changed to a property that did not easily peel off, and the pressure inside the reaction tube and the exhaust pipe was maintained at a low vacuum of less than atmospheric pressure to several hundred torr. Since the temperature change of the exhaust piping system when shifting from the state to the atmospheric pressure returning state in which the wafer is placed in the reaction tube is reduced, there is an effect that peeling of the deposit due to the thermal cycle is significantly suppressed.
Therefore, since the inside of the reaction tube and the exhaust system is kept in a clean atmosphere, the reliability of the wafer process is increased, and the production yield of the semiconductor device is improved. Ma
Ejector type vacuum pump without mechanically driven parts
The pump has a certain degree of vacuum without
Can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chemical vapor deposition apparatus showing one embodiment of the present invention.

FIG. 2 is a sectional view of a conventional chemical vapor deposition apparatus.

FIG. 3 is a sectional view of a conventional chemical vapor deposition apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer 2 Board 3 Reaction tube 5 Heater 6 Gas inlet 7 Gas exhaust port 11 Large flow gas control device 12 Branch pipe 13 Ejector vacuum pump

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiko Kusakabe 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corp. Production Technology Laboratory (72) Inventor Shinichi Shindachi 4-1-1 Mizuhara Itami-shi Mitsubishi Electric Kita-Itami Works (72) Inventor Yoshihiko Okamoto 4-1-1 Mizuhara, Itami-shi Mitsubishi Electric Corporation Kita-Itami Works (72) Hironari Takahashi 4-1-1 Mizuhara Itami-shi Mitsubishi Electric Kita-Itami Works (56) References JP-A-64-35918 (JP, A) JP-A-1-288317 (JP, A) JP-A-3-106432 (JP, A) JP-A-2-98127 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/31 C23C 16/54 H01L 21/205

Claims (1)

(57) [Claims] A reaction tube for accommodating a wafer and a board on which the wafer is mounted; and a reaction tube installed around the reaction tube;
A heater for heating the wafer, a gas supply system having a gas inlet for supplying a reaction gas and an inert gas to the reaction tube, and a gas exhaust port for exhausting the reacted gas and the inert gas are provided. An exhaust piping system, wherein the gas supply system is provided with a large flow rate gas control device, and the exhaust piping system is provided with a branch pipe and a branch pipe .
Connected to a pipe to reduce the pressure inside the reaction pipe and exhaust pipe system.
A chemical vapor deposition apparatus provided with an ejector-type vacuum pump for maintaining a degree of vacuum of less than atmospheric pressure to several hundred torr .