Fluid handling – Self-proportioning or correlating systems – Supply and exhaust type
Reexamination Certificate
1998-05-04
2001-03-06
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Supply and exhaust type
C137S487500
Reexamination Certificate
active
06196251
ABSTRACT:
The present invention relates to a gas inlet device for a coating system which is provided with a gas reservoir which is connected to a supply chamber via a supply channel arrangement and whose supply channel arrangement can be closed from the supply chamber by means of a respective supply valve arrangement.
A gas inlet device of this type is known from patent publication DE 35 37 544 C1. This gas inlet device comprises a chain of four-way valves which are each allocated to a reaction gas. The individual four-way valves are connected to each other via two connections respectively in such a manner that the chain formed by the four-way valves has a passage channel which is continuously streamed through by a carrier gas and represents the supply chamber of the gas inlet device. The passage channel opens into a reaction vessel in which the material to be coated is located. The gas reservoir allocated to each four-way valve is connected via a gas reservoir line to a third connection of each four-way valve. A fourth connection of the four-way valves is connected to an exhaust channel. A first valve plunger disposed in the passage channel seals the gas reservoir line to the passage channel. The gas reservoir line is sealed to the exhaust channel by a second valve plunger operating in a push-pull manner to the first valve plunger.
The known gas inlet device is employed predominantly in processes such as gas phase epitaxy or molecular beam epitaxy to supply the reaction vessel with the reaction gases needed to carry out the coating. Very important is that the reaction gases are fed into the reaction vessel with great precision with regard to amounts and time.
As the push-pull operating manner of the first and second valve plungers only switches the gas flow from the gas reservoir between the passage channel and the exhaust channel, practically no fluctuations in pressure occur in the gas reservoir line nor in the gas reservoir. Moreover, the switching delays due to dead volume can be ignored, because the opening of the reaction gas line into the passage channel can be closed by the first valve plunger from the passage and because the components of the four-way valve located in the passage channel are continuously swept with the carrier gas.
Consequently, such a gas inlet permits switching the reaction gas flows close to real time and with great accuracy.
However, one drawback of the known gas inlet device is the high gas loss, which occurs when the gas is deflected in the gas line when the first plunger seals the gas reservoir line against the passage channel.
Based on this state of the art, the object of the present invention is to create a gas inlet device with which the flow of the gas to be fed into the supply line can be switched with high accuracy and close to real time without significant losses in gas.
This object is solved in that the supply channel arrangement is designed as a supply flow restrictor arrangement and that the gas pressure in the gas reservoir is adjustable with the aid of a pressure meter and is adjusted by a control flow restrictor arrangement which is connected to a gas source and which can be closed from the outside by means of a control valve arrangement controlled by the pressure meter.
Due to the fact that both the supply valves of the supply valve arrangement and the control valves of the control valve arrangement are closed from the outside, the volume of the gas reservoir is not changed by the switching procedures of the control valves and the supply valves. Consequently, the gas pressure in the gas reservoir also does not change appreciably by actuating the control valves or the supply valves. In this manner the gas pressure can be easily maintained (very precisely) constant with the aid of an accurate pressure meter and a regulating means. As a consequence that the gas reservoir is directly connected via the supply flow restrictor to the supply chamber, in the open state of the supply valves, the gas flow is determined with high accuracy. Moreover, as there is no dead volume, the gas flow can be switched on and off practically instantaneously.
In a preferred embodiment, the supply valve arrangement comprises a number of supply valves with which a supply flow restrictor allocated to each supply valve and connected to the gas reservoir can be closed, thereby permitting setting the gas flow from the gas reservoir into the supply chamber to multiple differing flow values or switching the gas flow in steps.
REFERENCES:
patent: 4395258 (1983-07-01), Wang et al.
patent: 4903722 (1990-02-01), Joseph et al.
patent: 4958658 (1990-09-01), Zajac
patent: 5094260 (1992-03-01), Stuart et al.
patent: 5257640 (1993-11-01), Delajoud
patent: 5363872 (1994-11-01), Lorimer
patent: 5443087 (1995-08-01), Myles
patent: 3537544C1 (1987-05-01), None
patent: 0337180A2 (1989-10-01), None
patent: WO 93/07451 (1993-04-01), None
patent: 0651189A2 (1995-03-01), None
AIXTRON Semiconductor Technologies GmbH
Michalsky Gerald A.
St. Onge Steward Johnston & Reens LLC
LandOfFree
Gas inlet device for a coating system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas inlet device for a coating system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas inlet device for a coating system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2523176