Patent ID: 6252354
Filing Date: 2001-06-26
Classification: H01J,H03H

Abstract:
In an RF plasma reactor comprising a reactor chamber with a process gas inlet, a workpiece support, an RF signal applicator facing a portion of the interior of said chamber, an RF signal generator having a controllable RF frequency and a controllable output power, and an RF signal output coupled to an input of said RF signal applicator, a tuning method comprising:selecting a desired plasma ion density value;measuring, near one of or between (a) the output of said generator and (b) at said signal applicator, a parameter governing a plasma ion density in said reactor, wherein said parameter consists of one of:(a) a Fourier component of the magnitude of the RF current flow to said RF signal applicator(b) the magnitude of the time rate of change in RF current flow in said RF signal applicator;adjusting said frequency of said RF signal generator so as to at least nearly optimize said parameter near an optimum value corresponding to said desired plasma ion density value; andadjusting said output power of said RF signal generator so as to maintain said parameter near said optimum value.