K. Ohwada et al., UNIFORM GROOVE-DEPTHS IN (110)SI ANISOTROPIC ETCHING BY ULTRASONIC-WAVES AND APPLICATION TO ACCELEROMETER FABRICATION, Sensors and actuators. A, Physical, 50(1-2), 1995, pp. 93-98
The use of ultrasonic waves to obtain uniform groove depth in (110) Si
anisotropic etching has been studied. Using dynashock-type ultrasonic
waves, the frequency of which is switched between three frequencies a
t very short intervals, grooves with uniform depth can be successfully
formed with widths of 1-20 mu m independently of pattern width and pa
ttern spacing. This technology is applied to the fabrication of an acc
elerometer with comb-type narrow-gap electrodes. Comb electrodes with
a minimum gap of 3.0 mu m and a height of 58 mu m can be formed unifor
mly, although they have different pattern widths and pattern spacings.
The capacitance of this device has a high sensitivity to acceleration
of 39 pF g(-1). By combining it with an output CV converter and ampli
fiers, we have produced a sensor with good full-scale linearity of 0.6
3% over the acceleration range 0 to + 2g.