Apparatus and method for providing a uniform flow of gas

A processing chamber comprising:

• a substrate support having a top surface with a process region above the top surface;
• gas distribution apparatus comprising:
• a gas distribution plate having an outer peripheral edge, a front side defining a top of the process region and a back side with at least one delivery channel recessed in the back side of a gas distribution plate, the delivery channel having an inlet end, an outlet end and a length, the delivery channel including a plurality of apertures spaced along the length extending through the gas distribution plate to the front side of the gas distribution plate;
• and
• an outer distribution ring around the outer peripheral edge of the gas distribution plate, the outer distribution ring comprising:
• a round body having a top, bottom, inner diameter with an inner diameter face and an outer diameter with an outer diameter face, the outer distribution ring positioned so that there is a gap between the outer peripheral edge of the gas distribution plate and the inner diameter face of the outer distribution ring;
• a plenum formed in the top of the round body, the plenum having an outer peripheral face and an inner peripheral face defining a width;
• at least one gas inlet in fluid communication with the plenum;
• and
• a plurality of openings in the inner peripheral face of the plenum forming a plurality of trenches connecting the plenum with the gap between the inner diameter face and the outer peripheral edge of the gas distribution plate, the plurality of trenches substantially equally spaced about the inner peripheral face,
• wherein the gap between the inner diameter face of the outer distribution ring and the outer peripheral edge of the gas distribution plate is shaped to direct a gas to flow down the inner diameter face from the plurality of trenches out a front of the gas distribution apparatus in a direction substantially concentric with an axis of the body into an outer edge region of the process region;
• a supplemental gas inlet in fluid communication with a supplemental gas line passing through the gas distribution apparatus to flow a supplemental gas into the process region;
• and
• a confinement ring defining an outer edge of the process region, the confinement ring comprising a plurality of openings to allow a flow of gas to pass from the process region to exhaust.

A gas distribution apparatus comprising:

• a gas distribution plate having an outer peripheral edge, a front side and a back side with at least one delivery channel recessed in the back side of a gas distribution plate, the delivery channel having an inlet end, an outlet end and a length, the delivery channel including a plurality of apertures spaced along the length extending through the gas distribution plate to the front side of the gas distribution plate;
• and
• an outer distribution ring around the outer peripheral edge of the gas distribution plate, the outer distribution ring comprising:
• a round body having a top, bottom, inner diameter with an inner diameter face and an outer diameter with an outer diameter face, the outer distribution ring positioned so that there is a gap between the outer peripheral edge of the gas distribution plate and the inner diameter face of the outer distribution ring;
• a plenum formed in the top of the round body, the plenum having an outer peripheral face and an inner peripheral face defining a width and having a volume in a range of about 100 mL to about 900 mL;
• at least one gas inlet in fluid communication with the plenum;
• and
• a plurality of openings in the inner peripheral face of the plenum forming a plurality of trenches connecting the plenum with the gap between the inner diameter face and the outer peripheral edge of the gas distribution plate, the plurality of trenches substantially equally spaced about the inner peripheral face, the plurality of trenches extending from a top of the inner diameter face to a bottom of the inner diameter face, and the trenches having a combined volume in a range of about 20 mL to about 240 mL,
• wherein a ratio of the combined volume of the trenches to the volume of the plenum is in the range of about 10% to about 30%.