Gas separation: apparatus – With gas and liquid contact apparatus – Diverse means for adding liquid for gas and liquid contact
Reexamination Certificate
1999-08-09
2001-02-13
Barry, Chester T. (Department: 1724)
Gas separation: apparatus
With gas and liquid contact apparatus
Diverse means for adding liquid for gas and liquid contact
C096S306000, C096S319000, C096S372000, C096S314000
Reexamination Certificate
active
06187080
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an exhaust gas treatment apparatus that includes a water vortex means and a discharge pipe and particularly to an exhaust gas treatment for treating exhaust gases generated in diffusion and deposition processes.
2. Description of the Prior Art
In semiconductor manufacturing process, a blank wafer has to go through hundreds of processes to equip it with function desired. The processes include 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 have reaction with the wafer and become exhaust gases. The exhaust gases mainly include SiH
4
, SiH
2
Cl
2
, etc. They are highly toxic and should be properly treated to remove the toxicity to comply with industry standards before being discharged out.
In the semiconductor industry nowadays, a commonly used treatment method for these toxic exhaust gases, such as SiH
4
, and SiH
2
Cl
2
, is to heat the exhaust gases to about 800° C. and to mix them with oxygen gas at high temperature to form a waste powder of SiO
2
compounds. The high temperature compounds then mix with cooling water to form a waste powder containing vapor and waste water for discharging. An exhaust gas treatment apparatus usually has to perform 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 knives located at the 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 gas, and a suction motor
162
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
, are heated by the heater
123
to form high temperature exhaust gas powders after having reaction with oxygen gas. The exhaust gases powder are then cooled by cooling water from the sprinkler
124
to form waste powder containing 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
.
However, when vapor and waste water that contain waste powder enter into the U-pipe
14
, some of the vapor may be reflux into the main pipe
12
. Waste powder contained in the vapor will accumulate around the outlet
122
and consequently shrink the diameter of the outlet
122
. Furthermore, the lump type waste powder scraped from the inside wall of the main pipe
12
by the scraper
125
drops down to and easily clogs the U-pipe
14
. All this makes exhaust gas discharge inefficient or difficult. Hence an exhaust gas treatment apparatus needs periodic preventive maintenance to clear the waste powder accumulated around the outlet
122
and in the U-pipe
14
. The preventive maintenance frequency is usually two to four times per week. The time and frequency needed for preventive maintenance of an exhaust gas treatment apparatus becomes a serious drag on wafer production efficiency. An improvement in exhaust gas treatment can greatly enhance wafer production efficiency.
SUMMARY OF THE INVENTION
It is a main object of this invention to provide an exhaust gas treatment apparatus. The invention includes a water vortex means and a discharge pipe, which can prevent vapor from incurring reflux in the main pipe so that the outlet of the main pipe will be free from waste powder accumulation, the scraper won't stick or deform, and the U-pipe won't clog.
In one aspect of this invention, the apparatus includes a main pipe, a gas vortex means, a water vortex means, U pipe, and a discharge pipe. The main pipe, U pipe and discharge pipe are generally organized and constructed like the conventional one set forth above. The gas vortex means and the water vortex means are disposed between the main pipe and the U-pipe for respectively generating annular gas flow and water flow evenly downward. Vapor and waste water thus may be prevented from refluxing into the main pipe. Waste powder accumulation phenomenon and its ensuing problem may be avoided. The U pipe thus won't clog. The scraper won't stick or deform. The exhaust gas treatment efficiency may be maintained at a high level.
REFERENCES:
patent: 5855822 (1999-01-01), Chen
patent: 6010576 (2000-01-01), Lin
patent: 6090183 (2000-07-01), Awaji
patent: 6095063 (2000-08-01), Lee et al.
patent: 6119299 (2000-09-01), Lin
Chen Chi-Hsien
Chen Chien-Feng
Chung Hunter
Huang Jing-Yi
Lee Ju-Long
Barry Chester T.
United Microelectronics Inc.
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