Before revision: Orientation-Dependent Etching KOH pellets dissolved in water (self-heating) Etch Rate {110} > {100} >> {111} KOH has a slower etching orientation for the {111} planes You cannot use this KOH photoresist as a etching mask, because the oxide attacks too slowly, so this resist will not survive Photoresist can be used a etching mask, and the best photoresist for etching is nitride For example, the etch rate of Si in KOH Depends on Crystallographic Plane At low temperature you have high selectivity (etching rate is slower), at high temperature your selectivity will drop (higher etching rate) By increasing the temperature, the etch rate increases, but the selectivity decreases.
After revision: Orientantion-Dependent Etching KOH pellets dissolved in was anter (self-heating) Etch Rate {110} > {100} >> {111} KOH has a slower etching orientation for the {111} planes You cannot use this KOH photoresist as a etching mask, because the oxide attacks too slowly, so this resist will not survive Photoresist can be used a etching mask, and the best photoresist for etching is nitride For example, the etch rate of Si in KOH Depends on Crystallographic Plane At low temperature you have high selectivity (etching rate is slower), at high temperature your selectivity will drop (higher etching rate) By increasing the temperature, the etch rate increases, but the selectivity decreases.