Gas supply system equipped with pressure-type flow rate control unit

• US 6,289,923 B1
• Filed: 06/02/2000
• Issued: 09/18/2001
• Est. Priority Date: 05/29/1998
• Status: Expired due to Term

• Current Assignee: Fujikin Incorporated, Tadahiro Ohmi, Tokyo Electron Limited
• Original Assignee: Fujikin Incorporated, Tadahiro Ohmi, Tokyo Electron Limited
• Inventors: Ohmi, Tadahiro, Yamaji, Michio, Yoshikawa, Kazuhiro, Ikeda, Nobukazu, Nishino, Kouji, Dohi, Ryousuke, Uno, Tomio, Ideta, Eiji, Kagatsume, Satoshi
• Primary Examiner(s): Michalsky, Gerald A.
• Application Number:
  US09/463,514
• Time in Patent Office: 473 Days
• Field of Search: 137/486, 137/487.5, 251/118
• US Class Current: 137/486
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10T 137/7759 Responsive to change in rate of fluid flow
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

An improved and reduced-size and low-cost gas supply system equipped with a pressure-type flow rate control unit, to be used, for instance, in semiconductor manufacturing facilities is disclosed. Transient flow rate characteristics are improved to prevent the gas from overshooting when the gas supply is started, and to raise the flow rate control accuracy and reliability of facilities. That eliminates non-uniformity of products or semiconductors and raises the production efficiency. The gas supply system equipped with a pressure-type flow rate control unit is so configured that with the pressure on the upstream side of the orifice held about twice or more higher than the downstream side pressure, the gas flow rate is controlled to supply the gas to a gas-using process through an orifice-accompanying valve, the gas supply system comprising a control valve to receive gas from the gas supply source, an orifice-accompanying valve provided on the downstream side of the control valve, a pressure detector provided between the control valve and the orifice-accompanying valve, an orifice provided on the downstream side of the valve mechanism of the orifice-accompanying valve and a calculation control unit where on the basis of the pressure P1 detected by the pressure detector, the flow rate Qc is calculated with an equation Qc=KP1 (K: constant) and the difference between the flow-rate specifying signal Qs and the calculated flow rate Qc is then input as control signal Qy in the drive for the control valve, thereby regulating the opening of the control valve for adjusting the pressure P1 so that the flow rate of the gas to supply can be controlled.

Claims

1. A gas supply system equipped with a pressure-type flow rate control unit configured so that with the pressure on an upstream side of an orifice held about twice or more higher than a downstream side pressure, the gas flow rate is controlled to supply the gas to a gas-using process through an orifice-accompanying valve, the gas supply system comprising:

a control valve for receiving gas from a gas supply source, said control valve having a valve block and a drive;

an orifice-accompanying valve provided on the downstream side of the control valve, said orifice-accompanying valve has a valve block, wherein the valve block of said control valve and the valve block of said orifice-accompanying valve are integrally formed;

a pressure detector provided between the control valve and the orifice-accompanying valve;

an orifice provided on the downstream side of the orifice-accompanying valve; and

a calculation control unit wherein, based on a pressure P1 detected by the pressure detector, a flow rate Qc is calculated with an equation Qc=KP1, wherein K is a constant, and the difference between a flow-rate specifying signal Qs and the calculated flow rate Qc is then input as control signal Qy into the drive for the control valve, thereby regulating the opening of the control valve for adjusting the pressure P1 so that the flow rate of the gas to supply can be controlled.

2. The gas supply system equipped with a pressure-type flow rate control unit as defined in claim 1, wherein the control valve is a direct touch metal diaphragm valve provided with a piezoelectric element actuating drive, wherein the orifice-accompanying valve is a direct touch metal diaphragm valve, and wherein the pressure detector is integrally incorporated into the valve block.

3. The gas supply system equipped with a pressure-type flow rate control unit as defined in claim 2, wherein said orifice-accompanying valve further comprises a solenoid-actuating drive.

4. The gas supply system equipped with a pressure-type flow rate control unit as defined in claim 2, wherein said orifice-accompanying valve further comprises an air pressure-actuating drive.

5. The gas supply system equipped with a pressure-type flow rate control unit as defined in claim 1, wherein said orifice-accompanying valve has a valve mechanism;

wherein said valve mechanism comprises;

an inner disk fitted in a valve chamber formed in the valve block;

a valve seat block fitted air-tightly into a valve seat block fitting hole formed in the inner disk, wherein said valve seat block has a valve seat, and a gas outlet communicating therewith in the center of said valve seat block; and

a metal diaphragm provided over said valve seat block and movable into and out of contact with the valve seat to close and open the fluid passage;

wherein an orifice for squeezing the gas outlet is formed integrally with said valve seat block at an upper end portion of the gas outlet of said valve seat block.

6. The gas supply system equipped with a pressure-type flow rate control unit as defined in claim 5, wherein the portion of said valve seat block wherein the orifice is formed is 0.03-0.1 mm in thickness.

7. The gas supply system equipped with a pressure-type flow rate control unit as defined in claim 1, wherein said orifice-accompanying valve has a valve mechanism;

wherein said valve mechanism comprises;

an inner disk fitted in a valve chamber formed in the valve block;

a valve seat block fitted air-tightly into a valve seat block fitting hole formed in the inner disk;

wherein said valve seat block has a valve seat, and a gas outlet communicating therewith in the center of said valve seat block; and

a metal diaphragm provided over said valve seat block and movable into and out of contact with the valve seat to close and open the fluid passage;

wherein an orifice for squeezing the gas outlet is provided in the gas outlet of said valve seat block.