Synchrotron‐Radiation‐Excited Etching of Silicon Wafer Enhanced by Disk‐Shaped CF 4 Plasma

A new etching method, synchrotron‐radiation‐excited etching of a silicon wafer enhanced with a disk‐shaped sheet CF 4 plasma is proposed. The synchrotron radiation was incident perpendicularly on a silicon wafer which was placed on the downstream side of a CF 4 plasma, and exposed simultaneously to the disk‐shaped CF 4 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 μm lines has been successfully fabricated. The characteristics of the disk‐shaped sheet CF 4 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.