Three types of rotational micromotors, stepping, harmonic, and gyro-like side-drives, are presented. The rotors, poles, and stators are made of a thick single crystal silicon layer by using boron-diffused silicon etch stop to define the thickness and using anisotropic dry etching to form narrow and deep separation gaps. The rotor stoppers are fabricated by polysilicon trench filling and sacrificial layer etching processes. The silicon chips are electrostatically bonded onto glass chips, followed by unmasked wafer dissolution, freeing the rotors so that they can move. The novel process successfully provided micromotors with a 50 mu m diameter rotor.
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