| 摘要 |
The present invention is embodied in a method of operating an inductively coupled plasma reactor for processing a semiconductor wafer, the reactor including a vacuum chamber for containing the wafer, a process gas source, a semiconductor window electrode facing an interior portion of the chamber, an inductive power radiator on an exterior side of the semiconductor window electrode, the inductive field having a skin depth generally decreasing with the frequency of the RF inductive field and with the density of the plasma in the chamber and generally increasing with the pressure inside the vacuum chamber, the inductive coupling of the RF field tending to approach extinguishment as the skin depth approaches the spacing between the wafer and the window electrode, a method for maintaining an intermediate plasma density inside the chamber without extinguishing the inductive coupling of the RF field, the method including operating the reactor at a selected flow rate of the process gas, a selected chamber pressure and a selected plasma source power level corresponding to the reduced plasma density, and maintaining the frequency of the RF field at least at a level sufficient to limit the skin depth to a depth less than the electrode-to-wafer spacing, whereby to maintain the inductive coupling of the RF field.
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