BARRIER HEIGHT LOWERING AND INSTABILITY OF GATE OXIDES DUE TO DILUTE HYDROFLUORIC-ACID PRETREATMENT

The influences of dilute hydrofluoric acid (DHF) treatment used in waf er cleaning processes for silicon large-scale integrated circuit fabri cation on thin oxide integrity was examined. Unstable current-voltage characteristics,decreased dielectric strength, and a lowering of barri er height were observed in a thin oxide (11 nm) MOS structure formed b y using DHF treatment in the preoxidation cleaning procedure. Positive charges produced by some particle-related contamination, inherent to DHF treated surfaces, are related to the barrier height lowering and t o the current decrease associated with electron trapping at the trap c enters.