Figure 2.

Formation of square and v-shaped groove cavities in silicon. (a) Small pyramids produced in the square cavity of Si (p-side) due to uncontrolled KOH concentration and temperature; (b) smooth favorable surface Si (p-side) with controlled KOH concentration and temperature; (c) Si (n-side) after removal of SiO₂; (d) uneven pyramid with long v-shaped groove in Si (n-side); (e) controlled v-shaped small pyramid in Si (front side of n-type); and (f) thin Si membrane with thickness of 1.17 µm. (a,b,f) Cross sectional view; (c–e) Top view.