Method and apparatus for removing polymer from the wafer backside and edge

A method of processing in a reactor chamber a wafer having a polymer layer on a backside of the wafer, comprising:

• placing the backside of the wafer on a support surface provided in the chamber that leaves exposed a peripheral annulus of the backside of the wafer;
• wherein the chamber comprises an arcuate side gas injection nozzle extending into the chamber through a cylindrical side wall of the chamber, and having an arcuate gas injection zone distributed along an arc adjacent an edge of the wafer;
• raising the support surface and wafer toward a ceiling gas distribution plate of the chamber and past said arcuate side gas injection nozzle to confine the wafer front side in a small gap between said wafer front side and a ceiling of the chamber;
• generating plasma by-products in a remote plasma source from a process gas comprising an oxygen-containing species and introducing the plasma by-products into the reactor chamber through the arcuate gas injection zone of the arcuate side gas injection nozzle to expose, to the plasma by-products, a section of the backside of the wafer subtended by said arc, to remove the polymer from the wafer backside;
• and
• blocking the plasma by-products from entering the gap between the wafer front side and the ceiling by introducing a purge gas through a gas distribution plate at the ceiling facing the wafer front side.