I understand silicon pitting happens subsequently to oxide wet etch while PR is used as protective mask. But how this occurs, what is the mechanism behind?
Surface of silicon is pitted when non homogeneous etching is carried out. Also when non homogeneous growth of oxide is occurred, then when etching the oxide the surface will appear pitted. Nonuniform oxidation occurs when the the oxidation rate is surface reaction rate dependent. That is some microscopic areas will be oxidized faster that the others. The areas with the higher rate will appear pitted after etching.
Thanks for your answer. It looks in my case that pitting happens during wet etch on a non homogenous dry etched oxide. The question I guess is what is the preventive action?