| abstract |
A method for measuring electron density n p of a plasma in a plasma reaction chamber for semiconductor fabrication processes is capable of an accurate measurement without time-drifting of measuring values and metal contamination to semiconductor wafers. The method comprises injecting electrons in the plasma to generate a plasma oscillation, getting a plasma oscillation frequency ω p by antenna and frequency analyzer, and easily computing n p by a well-known formula using the value of ω p . A plasma generating apparatus for semiconductor fabrication processes is capable of keeping the electron density in a plasma reaction chamber constant. The apparatus comprises feed-back circuits for feeding back a deviation signal of the computed (n p ) from a presetting value to an RF oscillator or a gas control unit so as to control RF power or pressure of a source gas, respectively. |