Abstract: A micromirror assembly comprises a first position-limiting part, a micromirror chip, and a second position-limiting part that are stacked. The micromirror chip includes a fastening frame, a movable part, and a first cantilever, where the movable part is connected to the fastening frame by the first cantilever. The first position-limiting part and the second position-limiting part are separately connected to the fastening frame, the first position-limiting part and the second position-limiting part have a hollow area, and the hollow areas are opposite to the movable part. The first position-limiting part and the second position-limiting part are configured to absorb shock from a collision with the micromirror chip, and a projection of a collision part of the first position-limiting part on the micromirror chip intersects with a central axis of the first cantilever.

Abstract: A selective etching method with lateral protection function is provided. The steps includes: (a) providing a substrate; (b) forming a plurality of tunnels; (c) forming a lateral strengthening structure at a peripheral wall of the tunnels; (d) removing a bottom portion of the lateral strengthening structure, and a part of the substrate by an etching process so as to form a lower structure and expose an unstrengthened structure; and (f) etching the unstrengthened structure laterally so as to form an upper structure.

Abstract: A high-aspect-ratio-microstructure (HARM) is provided. The structure includes: a substrate; a lower structure with a comb shape fixedly mounted on said substrate and having first plural comb fingers, wherein each of the first plural comb fingers has a thin slot thereon; an upper structure with a comb shape having second plural comb fingers, wherein the lower structure and the upper structure have a height difference therebetween so as to form an uneven surface; and a lateral strengthening structure formed at vertically peripheral walls of the first plural comb fingers and the second plural comb fingers for protecting the plural first and second comb fingers.

Abstract: A high-aspect-ratio-microstructure (HARM) is provided. The structure includes: a substrate; a lower structure with a comb shape fixedly mounted on said substrate and having first plural comb fingers, wherein each of the first plural comb fingers has a thin slot thereon; an upper structure with a comb shape having second plural comb fingers, wherein the lower structure and the upper structure have a height difference therebetween so as to form an uneven surface; and a lateral strengthening structure formed at vertically peripheral walls of the first plural comb fingers and the second plural comb fingers for protecting the plural first and second comb fingers.

Abstract: A selective etching method with lateral protection function is provided. The steps includes: (a) providing a substrate; (b) forming a plurality of tunnels; (c) forming a lateral strengthening structure at a peripheral wall of the tunnels; (d) removing a bottom portion of the lateral strengthening structure, and a part of the substrate by an etching process so as to form a lower structure and expose an unstrengthened structure; and (f) etching the unstrengthened structure laterally so as to form an upper structure.