Question

In a lattice of silicon in the <100> plane direction using etching in KOH, explain why the final shape of the etching, if carried out to completion, is an inverted square-based pyramidal pit. Find the length of the sides of its base, and its depth (assume that the wafer’s primary flat is approximately parallel to one of the straight portions of the mask opening).

the given opening for the mask is a round void with 200micrometer diameter.

thanks a lot

Answer 1

I think that the you have to look at the secondary flat to tell if your wafer is 100 or 111 and if there is no secondary flat the wafer is p type <100>. The angle between 100 and 110 is 45 degrees so I am not sure what you mean by being parallel. The wafer flat choices are a matter of convention. If you look up SEMI wafer standards you will find documents that go into detail about the specification.

If you count the number of bonds per unit area, I think you will find them be be less along the cleavage planes.