Specific Process Knowledge/Etch/KOH Etch: Difference between revisions
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Due to the almost inert (111)-planes it is possible by KOH etching to realize high aspect ratio structures in sigle crytalline silicon using the (111)-planes as sidewalls. In Si(100) these sidewalls are inclined - 54.7<sup>o</sup> with respect to the (100) surface - whereas in Si(110) the sidewalls are vertical (see figures below). | Due to the almost inert (111)-planes it is possible by KOH etching to realize high aspect ratio structures in sigle crytalline silicon using the (111)-planes as sidewalls. In Si(100) these sidewalls are inclined - 54.7<sup>o</sup> with respect to the (100) surface - whereas in Si(110) the sidewalls are vertical (see figures below). | ||
[[Image:KOH_Anisotropy.jpg]] | [[Image:KOH_Anisotropy.jpg|left|380px|thumb|Si(100)]] | ||
[[Image:KOH_Anisotropy(110).jpg|380px|thumb|Si(110)]] | |||
[[Image:KOH_Anisotropy(110).jpg]] | |||
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For Si(100), the relation between the width of the bottom of the etched groove (W<sub>b</sub>) and the width of the opening (W<sub>o</sub>) at the wafer surface in a groove etched to the depth l is given by: | For Si(100), the relation between the width of the bottom of the etched groove (W<sub>b</sub>) and the width of the opening (W<sub>o</sub>) at the wafer surface in a groove etched to the depth l is given by: | ||