Gas supply delivery arrangement including a gas splitter for tunable gas flow control

A gas supply delivery arrangement for supplying process gas to a chamber of a plasma processing system wherein a semiconductor substrate is processed with gases introduced through at least first, second, and third gas injection zones, comprising:

• a plurality of process gas supply inlets and a plurality of tuning gas inlets;
• a mixing manifold comprising a plurality of gas supply sticks each of which is adapted to provide fluid communication with a respective process gas supply;
• a plurality of tuning gas sticks each of which is adapted to provide fluid communication with a respective tuning gas supply;
• a first gas outlet adapted to deliver gas to the first gas injection zone, a second gas outlet adapted to deliver gas to the second gas injection zone, and a third gas outlet adapted to deliver gas to the third gas injection zone;
• a gas splitter in fluid communication with the mixing manifold, the gas splitter including a first valve arrangement which splits mixed gas exiting the mixing manifold into a first mixed gas which can be supplied to the first gas outlet and a second mixed gas which can be supplied to the second and/or third gas outlets;
• a second valve arrangement which selectively delivers tuning gas from the tuning gas sticks to the first, second and/or third gas outlets.