This is what DRIE does.  If you are using the Bosch process there is
no way to completely get rid of the scallops, but you can reduce them
by optimizing your process.  Higher substrate power and shorter
cycles should help out.

If you want to completely get rid of scallops I am told that the Cryo
process is a DRIE process that has no scallops (since there is no
cycling in that) but you need a special tool to do it (most DRIE
machines cannot switch between the two processes).

Nik

At 12:25 AM -0700 9/9/06, Shankar Dutta wrote:
>we are trying to do a DRIE etching (~15-20 micron deep) for comb
>like structure. the masking layer is 0.3micron oxide layer. we
>patterned the oxide layer by BOE etchant. after that we performed
>the DRIE experiment. but surprisingly we find some scalopes in
>etched area, as if it does some isotropic etching. is this problem
>related to paterning of oxide layer with BOE.