Patent ID: 7798167

Claim:
An internal pressure controller associated with a chamber, comprising: (a) a supply gas input part; (b) a supply gas output part connected to receive supply gas from the supply gas input part; (c) a gas flow rate control part operably connected between the gas input part and gas output part, wherein the chamber is connected to receive supply gas from the supply gas output part; and (d) a means to transmit pressure data of the chamber to the gas flow rate control part, wherein the gas flow rate control part includes i. a plurality of first pressure type flow rate controllers connected in parallel; and ii. a first controller operable to control the operation of the plurality of first pressure type flow controllers, wherein each of the first pressure type flow controllers comprises: (1) an orifice; (2) a pressure detector on an upstream side of the orifice; (3) a control valve provided on the upstream side of the pressure detector; and (4) a computation control part that outputs a difference Qy with a set flow rate Qs as a driving signal to the control valve by computing a gas flow rate Qc passing through the orifice with pressure P 1 detected by the pressure detector using formula Qc=KP 1 , where K is a constant, thus operating a respective one of the first pressure type flow controllers under a state wherein pressure P 1 is maintained more than approximately 2 times of pressure P 2 on the downstream side of the orifice, wherein one of the first pressure type flow controllers is operated as a second controller controlling the gas flow rate range up to 10% of the maximum flow rate supplied to the chamber while the remaining first pressure type flow controllers are operated as third controllers controlling the rest of the gas flow rate range of the maximum flow rate supplied to the chamber, wherein the second controller is initially operated to control the gas flow rate range up to 10% of the maximum flow rate, and when the gas flow rate reaches 10% of the maximum flow rate the third controllers are switched into operation, and wherein pressure data is inputted to the first controller to adjust a control signal to each of the first pressure type flow controller so as to control gas flow rate to the supply gas output part, wherein the chamber is connected to an evacuation system, and the evacuation system is connected to an additional gas supply pipe for adjusting an exhaust capacity of the evacuation system by supplying an additional gas to the evacuation system, during the process of controlling the gas flow rate by the first pressure type flow controllers, wherein the additional gas supply pipe comprises a second pressure type flow controller which adjusts a flow rate of the additional gas and controls the internal pressure of the chamber by reducing an exhaust capability of the evacuation system with the supply of the additional gas.