Patent ID: 7059363

Claim:
A method of supplying divided gas to a chamber from a gas supply apparatus equipped with a flow rate control system, characterised in that a gas G with a set flow rate Q is supplied into a chamber C at a prescribed flow rate ratio Q 1 /Q 2 from a gas supply apparatus 1 equipped with a flow rate supply system through a plurality of split supply lines GL 1 and GL 2 and shower plates 3 and 4 attached to the ends thereof, wherein, with split pressure-type flow-rate controllers FV 1 and FV 2 installed in said plurality of split supply lines GL 1 and GL 2 , control of the degrees of opening of said split flow-rate controllers FV 1 and FV 2 is commenced by means of an initial flow rate setting control signal from a divided flow-rate control board FRC causing the control valve CV of the split pressure-type flow-rate controller having the greater flow rate to open to its full extent, and the desired divided flow rates Q 1 and Q 2 are supplied through orifices 3 a and 4 a provided in said shower plates 3 and 4 by adjusting the pressures P 3 ′, P 3 ″ on the downstream side of the control valves CV, with the flow rates Q 1 and Q 2 being expressed by the formulae Q 1 =C 1 P 3 ′ and Q 2 =C 2 P 3 ″ (where C 1 and C 2 are constants determined by the sectional areas of the orifice holes 3 a and 4 a and the gas temperature on the upstream side of the orifice), thereby supplying the total amount Q=Q 1 +Q 2 into the chamber C.