Page 170 - Microsensors, MEMS and Smart Devices - Gardner Varadhan and Awadelkarim

150 SILICON MICROMACHINING: SURFACE

Silicon substrate Silicon substrate

(b)
EH CVD SiO 2 Poly-Si | LPCVD Si 3N 4 I I Thermal SiO 2

Figure 6.5 Process flow for freestanding polysilicon beams using (a) CVD and (b) thermal
silicon dioxide as the sacrificial layer

Piezoelectric
HV (w.r.t. ground) thin film
electrodes (tungsten) (ZnO, PZT, etc)

Polysilicon
Output connection
(ground electrode)
(a) point/area
Individual bar
expansion/contraction

(b) Net actuator displacement
Figure 6.6 Linear motion microactuator (a) perspective view and (b) expansion/contraction
and net displacement (Robbins et al. 1991)