Selective chemical vapor deposition of tungsten for microdynamic structures

A selective chemical vapor deposition (CVD) tungsten process is used to fabricate three-dimensional tungsten cantilever beams on a silicon substrate. Two beams form micromechanical tweezers that move in three dimensions by the application of potential differences between the beams, and between the beams and the silicon substrate. A high-deposition-rate selective tungsten CVD process is used to fabricate beams of greater than three microns thickness in patterned CVD SiO₂ trenches ion-implanted with silicon. Tweezer 200-μm in length with a cross section of 2.7 μm×2.5 μm close with an applied voltage of less than 150 V. The magnitude of the deflection and the beam profile are compared to results obtained using simulations of the electric field and dynamic mechanical simulations of the tweezers