Patent ID: 8043882

Claim:
A method of making a microminiature moving device, the method comprising: sandwiching an insulating layer between a surface of a single-crystal silicon substrate and a first surface of a single-crystal silicon layer; forming on a second surface of the silicon layer that is opposite the first surface: one or more movable-element masks for movable elements composed of a combination of narrow patterns, and one or more stationary-part masks for stationary parts composed of a combination of wide patterns wider than the narrow patterns; selectively gas-reactive dry etching the silicon layer vertically at portions exposed through the stationary-part masks and the movable-element masks to expose portions of the insulating layer and form sidewalls of the silicon layer; covering the sidewalls with sidewall protective films; etching the exposed portions of the insulating layer to expose portions of the surface of the substrate, thereby: obtaining the stationary parts in the silicon layer under the stationary-part masks, which are fixed to the surface of the substrate by the insulating layer, and obtaining the movable elements in the silicon layer under the movable-element masks, which are fixed to the surface of the substrate by the insulating layer; isotropically etching the exposed portions of the surface of the substrate until regions of the surface 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 held by the stationary parts to be displaceable in parallel to the surface of the substrate with the insulating layer thereunder, and giving stationary parts overhanging portions of the first surface that overhang the depressions with the insulating layer thereunder; removing the stationary-part masks and the movable-element masks and the sidewall protective films; and removing the insulating layer under the movable elements and under the overhanging portions and portions adjacent to the overhanging portions of the stationary parts so that the insulating layer is indented from the overhanging portions of the stationary parts and edges of the depressions at the surface of the substrate.