Patent ID: 7666479

Claim:
A method for supplying at least one process gas to a plasma processing device using a gas injection system including a plurality of regions into which all gas injection orifices of the gas injection system are divided, the method comprising: sequentially starting and stopping at different periods of time the at least one process gas within a process chamber of the plasma processing device at each of the plurality of regions relative to the other of the plurality of regions, the sequentially starting and stopping including cyclically providing at a first gas flow rate the at least one process gas for a first period of time within the plasma processing device at a first region of the gas injection system; cyclically providing at a second gas flow rate the at least one process gas for a second period of time within the plasma processing device at a second region of the gas injection system; and performing the cyclically providing at the first gas flow rate and the cyclically providing at the second gas flow rate for a third period of time, wherein the first period of time partially overlaps the second period of time during an overlap period ranging between 0.1 and 1 second; controlling total gas flow rate of the at least one process gas to the plasma processing device to rise during the overlap period and fall to a substantially steady level outside of the overlap period.