Dalsa Semiconductor Inc.

Riopel Yan

Robert Antaki

Annie Vachon

A method is disclosed for evaluating an anisotropic etch in a microstructure. First a film is formed on a substrate. Next a series of holes of progressively different area and having specific geometric shapes are formed through the film. An anisotropic etch is carried out in the microstructure through the holes by relying on different etch rates in different crystal planes under known and reproducible conditions. Finally, the microstructure is inspected through the holes after the anisotropic etch to compare results from holes of different area. The method is useful in the determination of etch depth.

Method of inspecting an anisotropic etch in a microstructure

In order to align a mask to a specific crystal plane in a wafer, a first mask having at least one alignment structure is deposited on the wafer surface. The alignment structure is coarsely aligned with the specific crystal plane and has an array of components that are offset relative to each other by known angles defining the degree of precision with which said mask can be finely aligned with said crystal plane. Next, an anisotropic etch is performed through the first mask to etch the alignment structure into the wafer surface. The components of the alignment structure produce different etch patterns in the wafer surface according to their relative orientation to the specific crystal plane. Finally, a second mask is formed on the wafer surface having a reference structure thereon. The reference structure on the second mask is aligned relative to an etch pattern identified as being finely aligned with the specific crystal plane.

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Bromont, Canada

Riopel Yan