Gas separation: apparatus – With gas and liquid contact apparatus
Reexamination Certificate
1999-08-09
2001-04-17
Smith, Duane S. (Department: 1724)
Gas separation: apparatus
With gas and liquid contact apparatus
C055S423000, C096S273000, C096S322000
Reexamination Certificate
active
06217640
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Filed of the Invention
This invention relates to an exhaust gas treatment apparatus and particularly to an exhaust gas treatment apparatus for diffusion and deposition processes.
2. Description of the Prior Art
In semiconductor manufacturing process, a bare wafer has to go through hundreds of processes to be equipped with the desired function. The processes include microphotography, diffusion, deposition (particularly chemical vapor deposition, or CVD), etching and the like. These processes mostly require large amount of reaction gases, especially in the diffusion and deposition processes. While a small portion of the gases have reaction with the wafer, a great portion of the gases do not react with the wafer and become exhaust gases. The exhaust gases mainly include SiH4, SiH2Cl2, NF3, etc. They are highly toxic and should be properly treated to remove the toxicity to comply with industry standards before being discharged out.
In semiconductor industry nowadays, a commonly used treatment method for these toxic exhaust gases such as SiH4, SiH2Cl2, NF3 is to heat the exhaust gases to about 800° C. and to mix with oxygen gas at high temperature to form powders of SiO2 compounds. The high temperature compounds then mix with cooling water to form vapor and waste water for discharging. An exhaust gas treatment apparatus usually has to be equipped with the function set forth above to handle the exhaust gases generated in the diffusion and deposition processes.
FIG. 1
illustrates a conventional exhaust gas treatment apparatus
10
which includes a main pipe
12
, an U pipe
14
and a discharge pipe
16
.
The main pipe
12
includes an inlet
121
at an upper end thereof, an outlet
122
at a lower end, a heater
123
surrounding the main pipe
12
, a sprinkler
124
consisting of a plurality of nozzles and being located at a lower portion of the main pipe
12
in the center for providing cooling water required for exhaust gas treatment, and a scraper
125
which has a plurality of scraping knifes and being located at inside wall of the main pipe
12
. The scraper
125
is driven by a transmission means
126
for removing lump type exhaust gas powder
20
adhering to the inside wall of the main pipe
12
.
The U pipe
14
includes a pipe body
143
, a first connector
141
located at one end of the pipe body
143
and connected with a bottom end of the main pipe
12
, a second connector
142
located at another end of the pipe body
143
, and a drain
144
located below the second connector
142
.
The discharge pipe
16
has a bottom end connecting with the second connector
142
, filters
161
located inside for filtering exhaust gases, and water nozzles
162
for spraying water to flush exhaust gas powder in the discharge pipe
16
to speed up exhaust gas treatment process.
Exhaust gases generated in the diffusion and deposition processes flow in the main pipe
12
through the inlet
121
, and are heated by the heater
123
to form high temperature exhaust gas powders after having reacted with oxygen gas. The exhaust gas powder is then cooled by cooling water from the sprinkler
124
to form vapor and waste water which enter into the U pipe
14
through the outlet
122
and the first connector
141
. Vapor continues to flow through the second connector
142
and is discharged out through the discharge pipe
16
. Waste water is discharged out through the drain
144
.
During exhaust gas treatment process, the inside wall of the main pipe
12
usually has exhausted gas powder deposited thereon which gradually forms lump type exhaust gas powder
20
sticking to the inside wall of the main pipe
12
. This will reduce exhaust gas treatment efficiency. Therefore it needs to turn the scraper
125
to remove the lump type exhaust gas powder
20
from the inside wall of the main pipe
12
for maintaining the desired process. However the removed exhaust gas powder
20
tends to drop down in the U pipe
14
and clog the gas flow passage in the U pipe. It also impedes exhaust gas discharge operation. Hence how to improve exhaust gas treatment process is one of the ongoing R & D subjects in semiconductor industry.
SUMMARY OF THE INVENTION
The main object of this invention is to provide an exhaust gas treatment apparatus that can streamline exhaust gas discharging process without the U pipe being clogged by the lump type exhaust gas powder.
In one aspect of this invention, the apparatus includes a main pipe, an U pipe, a discharge pipe and a tank. The main pipe, U pipe and the discharge pipe are generally organized and constructed like the conventional one set forth above. However there is a tank connected with the U pipe below the first connector. The lump type exhaust gas powder after being removed from the inside wall of the main pipe wall drop down and are stored in the tank for periodical disposal. As a result, the U pipe will not clog, and the exhaust gas treatment efficiency may be maintained at a high level.
REFERENCES:
patent: 5716428 (1998-02-01), Imamura
patent: 5855822 (1999-01-01), Chen
patent: 5972078 (1999-10-01), Collins et al.
patent: 6090183 (2000-07-01), Awaji
Chung Frank
Chung Ping-Chung
Huang Jing-Yi
Lu Tsung-Lin
Smith Duane S.
United Microelectronics Corp.
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