In Al, Au and Pt metal etching processes, low etching rate and low etc
hing selectivity are serious problems. To achieve a breakthrough in th
ese problems, metal etching by pulse-time-modulated plasma was investi
gated. In particular, the Au etching rate wets increased significantly
in the pulsed plasma even when the ion energy decreases. However, an
increase in the etching rate cannot be observed in Al etching. As a re
sult, it is speculated that the increase in the Au etching rate is cau
sed by the increase in the evaporation rate of Au etching products, wh
ich results from the injection of negative ions.