Patent ID: 6770213
Filing Date: 2004-08-03
Classification: H01L

Abstract:
A method of determining etch depth in a microstructure, comprising:providing a substrate; forming a protective film on said substrate; forming a series of holes of progressively different area and having specific geometric shapes through said film; performing an anisotropic etch in said microstructure through said holes to form hollow structures with inclined walls by relying on different etch rates in different crystal planes under known and reproducible conditions, said hollow structures reaching a maximum depth when said inclined walls meet; and inspecting said microstructure through said holes after said anisotropic etch to compare said hollow structures associated with holes of different area; identifying a particular said hollow structure of structures representing the boundary between those structures that have reached their maximum depth and those structures that have not; and deriving the etch depth at said boundary from the area of the associated holes or holes and the etch rate ratio for the different crystal planes.