Patent ID: 7476561

Claim:
A method of making a microminiature moving device, the method comprising: sandwiching an insulating layer between a single-crystal silicon substrate and a single-crystal silicon layer; forming a mask layer all over the silicon layer; patterning the mask layer to form masks for stationary parts and masks for movable elements displaceable in parallel to the surface of the substrate and composed of a combination of narrow patterns; selectively gas-reactive dry etching the silicon layer at portions exposed through masks until the insulating layer is exposed, in the process exposing silicon-layer sidewalls perpendicular to the surface of the substrate; covering the sidewalls with sidewall protective films; etching away the exposed insulating layer to expose the substrate, thereby obtaining the stationary parts as the silicon layer under the stationary-parts masks and fixed to the substrate by the insulating layer and obtaining the movable elements as the silicon layer under the movable-elements masks and fixed to the substrate by the insulating layer; isotropically etching the exposed substrate until surface regions of the substrate under the movable elements are etched away, thereby forming depressions in the surface of the substrate where the stationary parts are not present, leaving the movable elements disposed over the depressions, and giving stationary parts underside edges that overhang depressions and still have the insulating layer; removing the masks and the sidewall protective films; and removing the insulating layer under the movable elements and the insulating layer under the overhanging edges of the stationary parts wherein the sandwiching comprises sandwiching an insulating layer, formed by a silicon dioxide film, between the substrate and the silicon layer; and the forming comprises forming a mask layer from a silicon dioxide film thicker than the insulating layer all over the silicon layer.