A new etching method, synchrotron-radiation-excited etching of a silicon 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 wafer was enhanced when the silicon wafer was kept at a negative bias voltage. The etch rate increased linearly with increasingly negative bias voltage up to the -300 V. Using the new etching method, a fine pattern of 0.125 mu m lines has been successfully fabricated. The characteristics of the disk-shaped sheet CF4 plasma used in the experiments were investigated in detail. The amount of species contributing to the etching process generated by the disk-shaped plasma can be controlled by adjusting the distance between the edge of the disk-shaped plasma and the silicon surface; The etching mechanism Is discussed.