first wafer:
1 – oxidation,
2 – Al evaporation,
3 – lithography & Al pattern,
4 – spin thick photo-resist as sacrificial layer for 4.6 lm,
5 – lithography, 6 – ploy silicon deposition (LPCVD), 7 –
lithography & poly silicon pattern, 8 – releasing the
structure; second wafer: 1 – silicon dry etching 2 – wafer
bonding.