Chemistry Reference
In-Depth Information
where is the side of the square apex or orifice, the side of the etched square
cavity in the wafer surface, and the etched depth or wafer thickness. The undercut-
ting due to the etching of the (111) planes represents the difference
between the mask opening and the intersect of the etched cavity wall with the mask.
Similar to fabrication of a cavity, a convex feature like pyramids can be fabricated by
etching a masked (100) silicon surface as shown in Fig. 7.45.
503,524,529
For a (110) wafer the geometries of the etched holes are different because the
four sets of {111} planes which form the sidewalls of the cavities are not equivalent.
Vertical grooves with a high aspect ratio can be obtained by etching a masked (110)
wafer because two sets of {111} planes are vertical to the (110) surface.
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