Patent ID: 7270729

Claim:
A method of etching an insulating layer in a wafer to present a clean and fresh surface on the insulation layer for a deposition on the insulating layer, including the steps of: providing a relatively strong electrical field at first positions in an enclosure, providing a relatively weak electrical field at second positions displaced in the enclosure from the first positions, the relatively weak electrical field defining a capacitor with a high impedance to limit the transfer of electrical charges to the insulating layer in the wafer, passing molecules of an inert gas through the enclosure, and providing a magnetic field in the enclosure in a direction relative to the strong electrical field to obtain a movement of electrons in the enclosure at the positions of the strong electrical field and an ionization of molecules of the inert gas by the electrons and a movement of the ions in a direction relative to the weak electrical field to obtain a movement of the ions, in accordance with the high impedance of the capacitor defined by the relatively weak field, to the second electrode at a speed for etching the surface of the insulating layer on the wafer substantially uniformly without pitting the insulating layer, wherein the capacitor constitutes a first capacitor and wherein the relatively weak electrical field is defined by the first capacitor and a second capacitor in a series circuit and wherein the first capacitor is defined by plates constituting an electrode and the wafer and in which the plates are separated by a space in which molecules and ions of the inert gas are disposed to define the insulator for the capacitor and to provide the first capacitor with the high impedance and wherein a second capacitor is defined by plates constituting the wafer and the ions of the inert gas in the enclosure and wherein the plates are separated by the insulating layer in the wafer to define the insulator of the second capacitor and to provide the second capacitor with a relatively low impedance in comparison to the high impedance of the first capacitor.