Fluid handling – With cleaner – lubrication added to fluid or liquid sealing... – Cleaning or steam sterilizing
Reexamination Certificate
1999-09-03
2001-07-10
Hepperle, Stephen M. (Department: 3753)
Fluid handling
With cleaner, lubrication added to fluid or liquid sealing...
Cleaning or steam sterilizing
C137S606000
Reexamination Certificate
active
06257270
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to fluid control devices, for example, for use in apparatus for producing semiconductors.
For example,
FIG. 6
shows a fluid control device for use in apparatus for producing semiconductors. The device consists of a plurality of lines each comprising a massflow controller
31
, two inlet on-off valves
32
,
33
provided at the inlet side of the controller
31
, and two or three outlet on-off valves
34
,
35
,
36
arranged at the outlet side of the controller. The inlet on-off valves
32
,
33
are used for selectively supplying one of two kinds of gases, i.e., process gas A and purge gas B, while the outlet on-off valves
34
,
35
,
36
are provided for a line leading to a process chamber, a vent line and an evacuating line for a change-over from one line to another. Process gas A is a gas of which high purity is required and which is expensive. Such a fluid control device has channels for passing the gases A and B, i.e., a main channel
37
in communication with the inlet of a channel within the massflow controller
31
, a relatively long subchannel
38
and a relatively short subchannel
39
. Conventionally, the relatively short subchannel
39
is thought useful for passing process gas A to be assured of high purity in ensuring the purity of process gas A and reducing the amount thereof to be used.
Our research has revealed that the use of the relatively short subchannel for passing the process gas which should be held at high purity eventually fails to assure the process gas of its purity and to achieve a reduction in the amount of the gas to be used.
An object of the present invention is to provide a fluid control device which is optimized in ensuring the purity of the fluid, such as process gas, to be assured of high purity and in reducing the amount thereof to be used, by introducing the concept of a minimized dead volume (stagnant portion of fluid) in connection with the fluid of which high purity is required.
SUMMARY OF THE INVENTION
The present invention provides a fluid control device wherein a valve main body has formed therein a main channel communicating with an inlet or outlet of a channel within a controller for regulating the pressure or flow rate of fluids, and a relatively long subchannel and a relatively short subchannel both communicating with the main channel, one of the subchannels being serviceable for a fluid to be assured of high purity, the fluid control device being characterized in that the subchannel for passing therethrough the fluid to be assured of high purity is the relatively long subchannel.
The expression that “the subchannel for passing therethrough the fluid to be assured of high purity is the relatively long subchannel,” when put in another way, can be expressed as the feature that the dead volume involved in passing the fluid to be assured of high purity is minimized.
The phrase a “relatively long subchannel” refers to the longer subchannel when the valve main body has two subchannels, or to the longest subchannel when the valve main body has three subchannels. When there are three subchannels, it is desired that the longer of the two remaining subchannels be used for a fluid which is the second in the order of importance of ensuring purity. With fluid control devices for use in producing semiconductors, the fluid to be assured of high purity is the process gas, and the fluid which is the second in the order of importance of ensuring purity is the purge gas.
The dead volume involved in passing the fluid to be assured of high purity is smaller in the fluid control device of the invention than in the conventional devices. This diminishes the reduction of purity occurring in starting to-pass the fluid of which high purity is required. Accordingly the present device produces optimized effects in ensuring the purity of the fluid to be assured of high purity and in reducing the amount of the fluid to be used.
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European Abstract No. 9710532.0, Tadahiro Ohmi, et al.
Hirao Keiji
Hirose Takashi
Ikeda Nobukazu
Minami Yukio
Ohmi Tadahiro
Armstrong Westerman Hattori McLeland & Naughton LLP
Hepperle Stephen M.
Ohmi Tadahiro
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