We are etching deep pits (50-100
microns) into Si using acid (HF-HNO3-
CH3COOH) etch. There is no problem with bare silicon, but when the wafer
has a mask of Ti/Au then a strong texture develops on the etched surface.
This is likely due to an electrochemical process or to contamination
of the etching solution. Before switching over to KOH, does anyone have
any ideas on the cause of the texture and its cure??