4 3D structures

The simple method for creating a microbridge is the following: Two triangular or rectangular shapes areas represent silicon exposed to anisotropic etch. The edges of the mask are aligned in <110> directions that will define the cavity. Undercutting the edges during the etching will create a microbridge on the top of a truncated pyramidal pit.

The method for designing a cantilever beam is based on the property of anisotropic etch to undercut convex corners. All edges of the mask are aligned with the <110> directions, which define a truncated pyramidal pit. When silicon is exposed to anisotropic etch, undercutting will start from both convex corners and will stop when <111> surface is reached. This will leave a suspended cantilever over the cavity.