Application of bottom purge to increase clean efficiency

A method of processing a substrate, comprising:

• positioning a substrate on a first surface of a substrate support disposed in a processing volume of a processing chamber, wherein the processing volume comprises a first volume disposed between a chamber lid and the substrate support and a second volume disposed between the substrate support and a chamber base;
• heating the substrate to a temperature between about 350° C. and about 550° C.;
• flowing a purge gas into the second volume, the purge gas comprising O2;
• flowing a gaseous precursor comprising TEOS into the first volume;
• forming a plasma of the gaseous precursor;
• exposing the substrate to the plasma;
• and
• depositing an oxide layer on the substrate while simultaneously evacuating a processing gas and the purge gas from the second volume,
• wherein the processing gas comprises one or both of unreacted TEOS gas or TEOS gas reaction byproducts,
• wherein the processing gas and the purge gas are evacuated through a combined gas exhaust volume disposed between a plane of a first surface and the chamber base,
• wherein the processing gas is evacuated from the first volume through a first gas inlet to the combined gas exhaust volume and the purge gas is evacuated from the second volume through a second gas inlet to the combined gas exhaust volume, and
• wherein an opening into the combined gas exhaust volume from the first gas inlet is located below the plane of the first surface and an opening into the combined gas exhaust volume from the second gas inlet is located above the plane of a second surface.

An processing chamber, comprising:

• a chamber body having a chamber base, one or more sidewalls, and a chamber lid defining a processing volume;
• a substrate support disposed in the processing volume, the substrate support having a first surface, a second surface opposite the first surface, and a third surface connecting the first surface and the second surface around a circumference of the substrate support;
• a first liner disposed in a circumferential channel in the chamber body,
• wherein the first liner is located between a plane of the second surface and the chamber base;
• a second liner disposed radially inwardly of the first liner,
• wherein the first liner and the second liner define an exhaust channel;
• and
• a third liner disposed radially inwardly of the one or more sidewalls between the first liner and the chamber lid,
• wherein the second liner, the third liner, and the third surface of the substrate support define a combined gas exhaust volume when the substrate support is in a raised position,
• wherein a first inlet to the combined gas exhaust volume is disposed between the substrate support and the third liner and a second inlet to the combined gas exhaust volume is disposed between the substrate support and the second liner when the substrate support is in the raised position, and
• wherein an opening into the combined gas exhaust volume from the first inlet is below the plane of the first surface and an opening into the combined gas exhaust volume form the second inlet is above the plane of the second surface when the substrate support is in the raised position.