ENHANCED DEGRADATION OF GATE OXIDE IN NEGATIVE-GAS PLASMA DURING REACTIVE ION ETCHING

The effect of gas species on the degradation of gate oxides due to pla sma exposure in reactive ion etching has been investigated. Gases test ed were H-2, Ar, Xe, and O-2. The oxide degradation was evaluated by a pplying a constant-current stress and measuring the charge-to-breakdow n Q(bd) of metal/oxide/silicon capacitors. It has been found that O-2 plasma significantly degrades the reliability of the gate oxide. Chara cterization of plasmas using a Langmuir probe has shown that O-2 gas t ends to produce nonuniform plasma because of its electronegative natur e, and thus enhances degradation of gate oxide. (C) 1998 American Vacu um Society. [S0734-211X(98)05302-5].