Pipe joints or couplings – For branched path – T-type
Reexamination Certificate
2000-02-29
2001-07-24
Fox, John (Department: 3753)
Pipe joints or couplings
For branched path
T-type
C137S798000
Reexamination Certificate
active
06264246
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a purge system for substituting inert gas for the process gas remaining in a piping system in a semiconductor manufacturing process line and a purge joint provided in the purge system, more particularly to a purge system with a purge joint, whereby an effective purging work of process gas can be performed for a short time for replacement of devices connected in the semiconductor manufacturing process line.
2. Description of Related Art
There have conventionally been used high poisonous gases such as silane gas and the like for process gas in a device or chamber such as a chemical vapor deposition (CVD) device used in a semiconductor manufacturing line. The device is connected to a piping system for process gas in the line and needed to be detached for replacement or maintenance. In that case, the process gas remaining in the device must be replaced completely with inert gas when the device is detached. Therefore, the device is connected to a purge gas piping system for supplying inert gas.
FIG. 5
schematically shows a piping system in a conventional purge system. A device
101
such as a CVD device is connected with a piping system for supplying process gas and purge gas. In the piping system are installed a valve
105
and a joint
104
. The joint
104
is connected to a purge gas supply source
110
via a valve
103
and a pressure regulation valve
102
. The joint
104
is also connected to a process gas supply source
113
via a valve
112
.
The device
101
is also connected with a piping system with an outlet port
111
for recovering process gas. In this piping system are arranged a joint
107
and a valve
106
. The joint
107
is connected to the outlet port
111
via a valve
109
, and also to a vent
114
for discharging the substituted gas through a valve
108
.
In the above conventional purge system, the device
101
is exchanged in the following manner.
First, the valve
112
is closed to stop the flow of process gas and the valve
109
is closed to prevent the flow of the substituted gas to the outlet port
111
. Then, the valves
103
and
108
are opened to allow purge gas such as nitrogen gas and the like to flow into the device
101
, discharging the mixed gas of the process gas and the nitrogen gas through the vent
114
. The substituted gas is discharged through the vent
114
, not through the outlet port
111
, in order to prevent the mixed gas including nitrogen gas from flowing in a process gas supply piping system. This is because there is a possibility that the mixed gas flowing in the supply piping system for process gas may cause the mixture of water or oxygen in the piping system, which may cause a problem.
The above system, however, has the following disadvantages. The amount of process gas used in the CVD device and the like is very small. The piping systems are so designed for allowing a small amount of gas to flow therein and therefore hard to allow a large amount of nitrogen gas to flow therein, so that it takes a long time to completely substitute nitrogen gas for process gas. This deteriorates a productive efficiency in the semiconductor manufacturing process.
To avoid the problem, a portable gas substitute device has been proposed in Japanese Patent publication No. 4-19899. If connected to a piping system, the gas substitute device can exhaust process gas and fill nitrogen gas in the piping system. More specifically, the device is provided with an exhaust pump, a substitute gas supply part, a pressure gauge, a gas sensor, a tank, and the like, which are mounted on a carriage so that the device is moved close to the piping system to be subjected to the substitution work of gas. Accordingly, this device can perform prompt has exhaustion/filling for the piping system to be subjected to the substitution of gas. Having only one connecting portion to the piping system and the tank for storing exhaust gas, the device can be portable to enhance the operating efficiency as compared with the conventional processing system.
However, the above purge system disclosed in Japanese Patent publication No. 4-19899 has the disadvantages as below.
The publication disclosing no way of connecting the device, though it is movable, to the piping system to be subjected to the substitution work of gas. It seems that the device needs to be connected to the piping system every purging operation, which is extremely troublesome in operation. There is also a possibility that the rubbing between the device and a metallic pipe to be connected with the device produces particles. Such the particles will cause defects in recent semiconductors with high precision which strictly require the prevention of production of particles.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a purge system and a purge joint whereby an effective purging operation can be performed for a short time, without producing particles.
Additional objects and advantages of the invention will be set forth in part in the description that follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a purge system comprising a purge gas piping system for substituting inert gas for process gas when a device connected to a process gas piping system is detached therefrom, the purge system comprising a purge joint for connecting two pipes in the purge gas piping system, and provided with an opening communicated with an outside at a position in alignment with a portion where the two pipes are connected.
According to another aspect of the invention, there is provided a purge joint for connecting two pipes comprising an opening communicated with an outside at a position in alignment with a portion where the two pipes are connected.
The function of the purge system and the purge joint constructed as above is explained below.
A device such as a CVD device is taken away by detaching a joint. The joint, which is generally a screw-type capable of providing a closed space therein, is detached by loosening a screw-threaded part, producing the clearance between two pipes connected by the joint. At this time, the process gas remaining in the pipes tries to leak from the clearance. The joint is provided with an opening at a portion corresponding to the connecting position of the two pipes and the opening is connected to the two-valves and the ejector. The process gas is sucked through the ejector for a predetermined time, for example, for a first few seconds, and discharged through the vent.
Succeedingly, the purge controller controls the two valves so as to be operated alternately every lapse of a predetermined time according to the air timers driven by air or gas. This purge controller is thus driven by air or gas, using no electricity, so that the purge system can be safely used without any special explosion-proof measure even if an explosive process gas is used.
The purge controller including the air timer may be driven by nitrogen gas for convenience, because the nitrogen gas is always supplied for inert gas to the purge system and needs no extra pipe therefor.
The switching of the two valves closes off a communication between the opening of the joint and the ejector and, alternatively, provides a communication between the joint and the nitrogen gas supply source. Accordingly, the nitrogen gas flows through the clearance into the two pipes, and is mixed with the process gas adhered to the wall surface and others of the pipes. After a predetermined time, the purge controller switches the valves again to cause the opening to be disconnected from the nitrogen gas supply source an
Goshima Kenichi
Sudo Yoshihisa
CKD Corporation
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Fox John
LandOfFree
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