Apparatus and methods for wafer chucking on a susceptor for ALD

A method of processing a wafer in a processing chamber, the method comprising:

• positioning a wafer in a recess in a top surface of a susceptor assembly, a central axis of the wafer offset from a central axis of the susceptor assembly, the wafer having a top surface and a bottom surface, the recess including at least one passage extending through the susceptor assembly to a bottom surface of the susceptor assembly;
• passing the wafer and susceptor assembly under a gas distribution assembly comprising a plurality of substantially parallel gas channels directing flows of gases toward the top surface of the susceptor assembly;
• creating a pressure differential between the top surface and bottom surface of the wafer so that the flow of gases directed toward the top surface of the wafer creates a higher pressure than the pressure at the bottom surface of the wafer, the pressure differential created within the at least one passage by a vacuum source;
• and
• directing a valve positioned between the bottom surface of the susceptor assembly and the vacuum source to allow a flow of a gas to pass through the at least one passage to the recess to provide positive pressure on the back side of the wafer to remove the wafer from the susceptor assembly.