Submicrometer Comb-Drive Actuators Fabricated on Thin Single Crystalline Silicon Layer

Electrostatic comb-drive microactuators were fabricated by electron beam lithography on a 260-nm-thick silicon layer of a silicon-on-insulator wafer. The actuators consisted of comb electrodes, springs, and a frame. Two kinds of microactuators with doubly clamped and double-folded springs were designed and fabricated. The comb electrode was as small as 2.5 mum wide and 8 mum long and was composed of 250-nm-wide, 260-nm-thick, and 2-mum-long fingers. The air gap between the fingers was 350 nm. The spring was 250 nm wide, 260 nm thick, and 17.5 mum long, and the spring constant was 0.11 N/m. The force and displacement generated by the microactuator were 2.3 x 10-7N and 1.0 mum, respectively. Applying an ac voltage, the oscillation amplitude became maximum at a frequency of 132 kHz. The mechanical and electrical characteristics of the fabricated actuators were investigated quantitatively.