Patent ID: 8052799

Claim:
A device fabrication process, comprising: providing an apparatus which includes: (a) a chamber bounded by an enclosure having a bottom surface, a top curved surface functioning as a lid of the chamber, and a side surface mechanically connecting the top surface to the bottom surface, wherein the chamber includes a first inlet and a second inlet, (b) an anode structure within the chamber and physically separated from the enclosure, wherein the anode structure comprises an anode surface, (c) a cathode structure within the chamber, wherein the cathode structure comprises a cathode surface, and (d) a wafer on the cathode structure such that a wafer surface of the wafer is on and in direct physical contact with the cathode surface, wherein the wafer is disposed between the cathode structure and the anode structure; injecting a cleaning gas into the chamber via the first inlet; injecting a collecting gas into the chamber via the second inlet; generating an electric field between the cathode surface and the anode surface, wherein the cathode surface is more negatively charged than the anode surface, wherein a first direction is perpendicular to the cathode surface and the wafer surface, and wherein the first direction is perpendicular to a surface normal direction at every spatial point on the anode surface; and ionizing the cleaning gas into a plasma comprising electrons and positive ions, wherein the positive ions are accelerated to the cathode surface by the electric field to etch a top surface of the wafer resulting in a by-product mixture in the chamber, wherein the collecting gas has a property of preventing the by-product mixture from depositing back to the surface of the wafer.