Question: does hf etch silicon nitride?
Answer: It will only attack silicon and silicon nitride at a very slow rate. ... You can also mask BOE etches with silicon nitride or Cr/Au [3]. - HF (40%) has an etch rate of approximately 833 nm/min at a temperature of 21 ˚C [4]. - BOE 7:1 has an etch rate of approximately 80 nm/min at a temperature of 21 ˚C [1].