Fluid handling – Diverse fluid containing pressure systems – Gas pressure storage over or displacement of liquid
Reexamination Certificate
1999-11-01
2001-01-09
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Diverse fluid containing pressure systems
Gas pressure storage over or displacement of liquid
C137S486000
Reexamination Certificate
active
06170512
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow control device, and more particularly, to a flow control device for controlling a flow of a chemical solution supplied by a supply apparatus.
2. Description of the Prior Art
In a semiconductor manufacturing process, many kinds of chemical solutions are used for cleaning, wet etching processes, etc. In order to precisely control the reactions of these solutions, the flow of the solution must be controlled to satisfy the flow velocity, volume and commixture ratios of the semiconductor process.
Please refer to FIG.
1
.
FIG. 1
is a schematic diagram of a prior art chemical solution supply apparatus
10
. The supply apparatus
10
is used to supply a chemical solution
12
for a semiconductor process. The supply apparatus comprises a storage tank
14
, a solution transfer device
16
, and a pressurizing apparatus
18
. The storage tank
14
serves as a reservoir for the chemical solution
12
. The pressurizing apparatus
18
supplies high-pressure gas into the storage tank
14
to pressurize the chemical solution
12
and thereby forcing it to flow into a semiconductor processing room (not shown). The solution transfer device
16
is used to route the chemical solution
12
into the processing room. The solution transfer device comprises a chemical flow pipe
20
to route the chemical solution
12
, a flow meter
22
, a switch valve
24
in series with the chemical flow pipe
20
and a nozzle
26
installed on the end of the chemical flow pipe
20
. The flow meter measures the flow of the chemical solution
12
. The nozzle
26
uniformly sprays the chemical solution
12
.
The pressurizing apparatus
18
comprises a gas input pipe
28
to route high-pressure gas from a high-pressure gas source
30
to the storage tank
14
. The pressurizing apparatus also comprises an adjust valve
32
and a gas meter
34
installed in series with the gas input pipe
28
for measuring and adjusting the pressure of the input gas into the storage tank
14
from the gas input pipe
28
.
However, in a typical semiconductor factory, for safety and convenience, the pipes for gas and those for liquids are independently installed and operated. During the operation of the prior art supply apparatus
10
, the user can only measure and adjust the pressure of the input gas by way of the adjust valve
32
and the gas meter
34
. So, during manufacturing operations, the pressure of the gas in the gas input pipe
28
holds a constant value and cannot be adjusted according to the rate of flow of chemical solution
12
as read from the flow meter
22
. When the solution transfer device
16
sends the chemical solution
12
into the processing room, the flow of the chemical solution
12
holds a constant value; for example, something like 130 cc/min. The chemical solution
12
used in the semiconductor process could be any combination of corrosive, poisonous or inflammable. Consequently, in the supply apparatus
10
, the chemical flow pipe
20
is made of a plastic material, and the installation of any intrusive mechanical or electrical equipment in the pipe is avoided in order to ensure a continuous seal along its length and to reduce the possibility of combustion or leakage. Therefore, the switch valve
24
has only a simplistic on and off ability, which does not require an intrusive mechanical or electrical apparatus. The only choices for flow control of the chemical solution are, in this example, 130 cc/min and 0 cc/min. If the user wants a different rate of flow (like 60 cc/min), the prior art supply apparatus
10
is unable to satisfy the request.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide an adjustable flow control device to solve the above mentioned problems.
In a preferred embodiment, the present invention relates to a flow control device for controlling a flow of a chemical solution supplied by a supply apparatus, the supply apparatus comprising a storage tank for storing the chemical solution, a chemical flow pipe to route the chemical solution into a semiconductor processing room, a pressurizing apparatus to supply gas to the storage tank to make the chemical solution flow into the processing room, the flow control device comprising:
a flow sensor installed in the chemical flow pipe for measuring the flow of the chemical solution in the pipe and generating a relative measurement value; and
a control unit comprising a set-up apparatus for setting a target value and a processor electrically connected with the flow sensor and the pressurizing apparatus for generating a control signal to the pressurizing apparatus depending on a difference between the target value and the measurement value to adjust the flow of the chemical solution in the chemical flow pipe, until the measurement value reaches the target value.
It is an advantage of the present invention that the flow control device can automatically adjust the pressure of the gas and thereby supply different rates of chemical flow to satisfy various user or process requirements.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings.
REFERENCES:
patent: 3380462 (1968-04-01), Schieber et al.
patent: 5148945 (1992-09-01), Geatz
Huang Kuo-Feng
Lai Kuei-Hsi
Mar Hung-Lung
Yang Ming-Che
Hsu Winston
Michalsky Gerald A.
United Microelectronics Corp.
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