Formation Of Submicron Silicon-Nitride Patterns By Lift-Off Method Using ECR-CVD

Abstract

Submicron silicon-nitride patterns were successfully formed by lift-off method using an electron cyclotron resonance (ECR)CVDsystem. In this system nitrogen or ammonia gas is introduced into the plasma chamber and is excited under ECR condition (2.45GHz microwave power and 875 Gauss magnetic flux density), and the plasma was extracted into deposition chamber filled with silane gas. The temperature of wafer surface increased gradually with increasing deposition time, but remained less than 105°C. A lift-off process with dimethyl ketone was carried out after slight-etching by hydro fluoric acid. Up to 5000Å thick patterns of SiN were formed. A 1500Å thick SiN pattern on GaAs wafer were annealed at 820°C for 20 minutes. SiN patterns maintained their shape and there was no out-diffusion of Ga and As into SiN. Films were characterized by FT-IR and ESR. Both SiN films formed by nitrogen and ammonia showed good etch resistance compared with films formed by plasma enhanced CVD or Sputtering.