SYNCHROTRON-RADIATION-EXCITED ETCHING OF SILICON-WAFER ENHANCED BY DISK-SHAPED CF4 PLASMA

A new etching method, synchrotron-radiation-excited etching of a silic on wafer enhanced with a disk-shaped sheet CF4 plasma is proposed. The synchrotron radiation was incident perpendicularly on a silicon wafer which was placed on the downstream side of a CF4 plasma, and exposed simultaneously to the disk-shaped CF, plasma. Etching of the silicon w afer was enhanced when the silicon wafer was kept at a negative bias v oltage. The etch rate increased linearly with increasingly negative bi as voltage up to the -300 V. Using the new etching method, a fine patt ern of 0.125 mu m lines has been successfully fabricated. The characte ristics of the disk-shaped sheet CF4 plasma used in the experiments we re investigated in detail. The amount of species contributing to the e tching process generated by the disk-shaped plasma can be controlled b y adjusting the distance between the edge of the disk-shaped plasma an d the silicon surface; The etching mechanism Is discussed.