Anisotropic etching of a novalak-based polymer at cryogenic temperature

A radio-frequency induction plasma etcher with cryogenic capabilities has been used to achieve anisotropic etching of a novlak photosensitive polymer with pure oxygen. At -100 degrees C wafer chuck temperature, etching profiles and etching residues were observed at various power and pressure conditions. These etching results are discussed with the aid of response surface maps of de bias voltage vs. inductive power bias power, and pressure. It is demonstrated that submicron features with aspect ratios as high as 15:1 can be achieved using the optimized conditions.