A SIMPLE FABRICATION PROCESS FOR POLYSILICON SIDE-DRIVE MICROMOTORS

A simple fabrication process for rapid prototyping of side-drive polysilicon micromotors has been developed. This process uses three tow-pressure chemical vapor depositions and three photolithography steps, and it enables fabrication of new micromotors and flange bearing designs. An important feature of this process is that the rotor, stator, and rotor/stator gap pattern definition is the first photolithography step and is performed over a flat surface. As a result, excellent linewidth resolution is possible for defining the rotor/stator gaps. Conventional wobble and salient-pole micromotors fabricated with this process have been operated for months after release. For wobble micromotors with 3-mu m-thick rotor/stator polysilicon films, minimum operating voltages have been 25 V across 1.5-mu m rotor/stator gaps; maximum operating speeds have been 1000 rpm, limited by the power supply. Corresponding salient-pole micromotors have had minimum operating voltages of 50 V; their maximum operating speeds have been near 5000 rpm. [112]