Patent ID: 7467598

Claim:
In combination for etching an insulating layer in a wafer to present a clean and fresh surface on the insulating layer for deposition, a conduit for molecules of an inert gas, a first electrode biased to a first voltage and spaced from the wafer, a second electrode biased to a second voltage lower than the first voltage and spaced from the first electrode and the wafer and spaced from the wafer less than the first electrode, magnetic members providing a magnetic field, the first electrode and the magnetic members being disposed relative to each other and to the molecules of the inert gas for ionizing the molecules of the inert gas, and the second electrode and the wafer being disposed relative to each other and to the ions of the inert gas, and the second electrode being constructed, to obtain a movement of the ions to the wafer at a low and controlled speed for an etching of the surface of the insulating layer by the ions at the low and controlled speed.