| 摘要 |
First and second electrodes and magnets between the electrodes define an enclosure. The first electrode is biased at a high voltage to produce a high intensity electrical field. The second electrode is biased at a low negative voltage by a low alternating voltage to produce a low intensity electrical field. Electrons movable in a helical path in the enclosure near the first electrode ionize inert gas molecules in the enclosure. A wafer having a floating potential and an insulating layer is closely spaced from the second electrode. The second electrode and the wafer define plates of a first capacitor having a high impedance. The wafer and the inert gas ions in the enclosure define opposite plates of a second capacitor. The first capacitor accordingly controls and limits the speed at which the gas ions move to the insulating layer surface to etch this surface. The resultant etch, only a relatively few angstroms, of the insulating layer is smooth, uniform and accurate.
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