PULSE-MODULATED MICROWAVE PLASMA-ETCHING

Studies have been conducted on the etching characteristics of Si in a microwave plasma etching system having a pulse-modulated source. The experiments were performed at several pulse widths and duty cycles, as well as at cw, to determine how etch rate varied. Results indicate that the etch rate of Si increases and approaches that in a cw discharge as pulse width decreases even though total microwave energy is markedly reduced. Langmuir probe measurements suggest that these effects may be due to increased ionization early in the plasma pulse.