What is micromachining? Explain the steps involved
Surface micromachining builds microstructures by deposition and etching structural layers over a substrate.
Typical steps in a surface micromachining process: (a) substrate preparationtypically, a 500 ÷ 700 μm thick single silicon (Si) crystal; (b) deposition of a sacrificial layertypically, a 1 ÷ 2 μm thick silicon dioxide (SiO2 ) layer; (c) creation of a hole by patterning (photoresist deposition + optical lithography) and etching of the sacrificial layer; (d) deposition of a structural layer-typically, a 1 ÷ 5 μm thick polysilicon layer; (e) shape definition by patterning and etching of the structural layer; (f) release of the suspended structure (e.g. a cantilever beam).