Patent ID: 6363958
Filing Date: 2002-04-02
Classification: G05D,Y10T

Abstract:
A method of controlling the batchwise delivery of process gas for semiconductor manufacturing using a flow control system operable in a flow mode for delivery of a batch of process gas and, alternately, in a no-flow mode, said method comprising:delivering a batch of process gas from a source of pressurized process gas through a flow line of said flow control system to a semiconductor manufacturing apparatus at a controlled flow rate for a delivery period of time, said line of the flow control system including a pressure regulator for establishing a regulated pressure of said process gas in said line, an on/off valve downstream of said pressure regulator to start and stop said flow mode during which said process gas is delivered to said apparatus for said delivery period of time and, upstream in said line from said pressure regulator, a reference capacity used to measure the actual flow rate of said delivering, and upstream in said line from said reference capacity, means for interrupting the flow of gas from the source of pressurized gas to the reference capacity during delivery of the gas by the flow control system, after the start of said delivering of said batch of process gas, measuring for a measurement period of time during said delivery period of time the pressure drop of said process gas in said reference capacity while interrupting the flow of process gas through said line to said reference capacity with the means for interrupting and continuing to deliver said batch of process gas from said line of said flow control system to said semiconductor manufacturing apparatus at said controlled flow rate, determining from said measuring the rate of pressure drop in said reference capacity during said measurement period and the actual flow rate of said batch of process gas being delivered and, in case said actual flow rate does not agree with a specified flow rate for said delivering, adjusting said controlled flow rate in the direction of said specified flow rate from said actual flow rate for a subsequent delivery period of time in which another batch of process gas is delivered.