Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
1999-03-25
2003-04-08
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S113000, C422S168000, C422S171000, C096S113000, C096S116000
Reexamination Certificate
active
06544483
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a gas scrubber which can dispose of harmful gases used in or generated by a semiconductor manufacturing process. More particularly, the gas scrubber is an adsorbent gas scrubber which treats gas by letting the gas pass through an adsorbent case having catalytic-adsorbent particles contained within multiple layers of catalytic-adsorbent members.
2. Description of the Related Art
Generally, when manufacturing a semiconductor product, gases having harmful, flammable and corrosive properties are used. For example, in the process of forming a semiconductor, Chemical Vapor Deposition (CVD), Low Pressure CVD, Plasma CVD, Plasma Corrosion, and Epitaxy CVD processes may be used which employ gas materials such as SiH
4
, SiH
2
Cl
2
, 4NH
3
, NO, AsH
3
, PH
3
, B
2
H
6
, BCl
3
.
The gas produced during the process of the semiconductor manufacturing contains harmful materials, such as SiH
4
, SiH
2
Cl
2
, 4NH
3
, AsH
3
, PH
3
, B
2
H
6
, BCl
3
, WF
6
, PBr
3
, (C
2
H
5
O)
4
Si, (C
4
H
9
)
3
Al, and the organic materials accumulated in a high density form. In order to prevent or minimize environmental contamination or pollution through leakage of the gas materials into the atmosphere, regulations for the application of the law are strictly enforced to purify the exhaust gas before the gas is exhausted into the atmosphere.
There are typically three methods used to dispose the toxic gases used or produced during, for example, semiconductor manufacturing. First, flammable toxic components contained in the exhaust gas may be burned at high temperature of 500° C. or 800° C. within a burning chamber. Second, water-soluble toxic components contained in the exhaust gas may be dissolved by wetting the water-soluble toxic components as they pass through water stored in a bath. Third, certain toxic components which cannot be burned or melted, may be adsorbed whereby toxic components are decomposed physically and chemically gas they pass through the adsorbents.
When the above burning method is used for disposing the toxic components contained in the exhaust gas, SiH
4
, one of the toxic components contained in the generated gas, may be burned with oxygen in air resulting in creation of silicon dioxide. Unfortunately, the silicon dioxide causes several problems. First, the silicon dioxide particles may form as a result of a gas phase reaction which could clog gas passages in the burner, and in some instances cause mechanical problems in the burning system. Second, the silicon dioxide is generally collected through a washing process and water used in the washing process must be treated to completely remove any of remaining chemical particles or other contaminated materials before disposal.
The wetting method consists of two processes, one being a wet chemical solution which is used to dispose the toxic components of the exhaust gas that are water-soluble, and the other being a dry chemical solution which is used to dispose non-water soluble material by dissolving them chemically. However, even though the above wetting method is effective in treating the gas produced during the semiconductor manufacturing process, it is generally less preferred because the used water or chemical solution must be treated before being discharged from a factory in order to meet more toughened world-wide water pollution standards.
The gas adsorbent method is used to dispose the toxic components contained in the gas by creating the following examples of physical or chemical reactions while certain toxic components pass through the catalytic-adsorbent material:
2SiH
4
+WF
6
→WSi
2
+6HF+H
2
SiH
4
→Si+2H
2
B
2
H
6
→2B+3H
2
However, the above adsorbent method has a problem in that the adsorbent must be frequently replaced with new adsorbent because the adsorbent particles agglutinate with the toxic compounds and, over time, clog the gas flow passages therebetween. This will eventually lead to a decrease in a gas flow rate of the gas that passes through the adsorbent particles.
Accordingly, it would be of benefit to provide an adsorbent gas scrubber which can effectively dispose the harmful gas generated during the semiconductor manufacturing process and decrease the system idle time by providing a construction that allows for easy replacement of the adsorbent case and adsorbent particles within the case.
SUMMARY OF THE INVENTION
The problems outlined above are in large part solved by an adsorbent gas scrubber. The present gas scrubber may include a cabinet which houses an induction tube that functions similar to a manifold or valve for coupling gas from a gas intake to corresponding gas passage tubes. The gas inlet is preferably attached to and in gaseous communication with a first pressure gauge for measuring a pressure of gas entering the gas inlet (or gas intake valve). The cabinet further houses an adsorbent case placed adjacent to the induction tube. The adsorbent case may include multiple layers of catalytic-adsorbent members configured to adsorb the gas as the gas flows from the induction tube into the adsorbent case. Coupled to an output of the induction tube is a gas outlet. Attached to the outlet valve is a second pressure gauge for measuring pressure of the processed gas being discharged. A gas passage extends at the bottom portion of the induction tube and the adsorbent case for supplying the gas to a catalytic-adsorbent member located in the bottom of the adsorbent case. Gas flow from the induction tube to the adsorbent case is controlled among several layers of catalytic-adsorbent members to either allow gas flow or to block gas flow into each of several catalytic-adsorbent members stacked a spaced distance from each other in the adsorbent case. The gas flow is regulated based on the pressure difference between the first pressure gauge and the second pressure gauge.
According to another embodiment, the adsorbent gas scrubber further includes a pipe tube which connects the gas intake and the gas outlet. A first open/shut valve is preferably located on the gas intake in the path between the gas intake and the gas outlet, and a second open/shut valve is preferably placed in the pipe tube.
According to yet another embodiment, the gas passage tube between the induction tube and the adsorbent case includes a multi-layer piston material that operates when the pressure difference between the intake gas pressure and the outlet gas pressure measured by the first and the second pressure gauge is larger than the threshold value. The multi-layer piston material preferably is several pistons, each of which control gas flow within a respective gas passage tube that extends between an opening within the induction tube and an opening within a catalytic adsorbent case. Similar to the catalytic adsorbent cases stacked within the adsorbent case, gas passage tubes deliver gas into respective cases and the gas flow therein is regulated by moving the associated piston. Thus, the pistons controls flow within the multi-layer tube material that extends between one side of the induction tube and one side of the adsorbent case, where a stacked arrangement of adsorbent cases reside.
Preferably, one end of each gas passage tube is connected to an opening of the induction tube, and a middle portion of the gas passage tube is connected to and opens onto an opening of the adsorbent case and, more particularly, to an opening of the adsorbent case. The piston reciprocates within the gas passage tube and resides from a location opposite the end connected to the induction tube when the induction tube becomes connected to the adsorbent case.
The above mentioned catalytic-adsorbent member is fixed onto an inner surface of the adsorbent case by a supporter. The supporter is placed between pairs of adsorbent cases stacked a spaced distance from each other within the cylindrically shaped adsorbent case having an opening at the top of the case. Each adsorbent case includes a tube opening that is connected to the middle part of a resp
Conley & Rose & Tayon P.C.
Daffer Kevin L.
Korea M.A.T. Co., Ltd.
Tran Hien
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