Effects of nitrogen additive gas on sidewall passivation in W/TiN/high-k dielectric gate etching

In manufacturing microelectronic devices, local pattern distortions such as notching have been frequently observed in gate etch processes when the etching was specifically associated with high density plasmas. Recently, high-k materials have been incorporated as gate dielectrics to meet a requirement for sub-100 nm scale devices. The use of the high-k dielectric materials has replaced the polysilicon-based gate with metal gates to overcome some limitations, such as the gate depletion effect and the gate-line sheet resistance. In this study, we have investigated the etching characteristics of W/TiN gate electrodes coupled with thin high-k dielectric layers, such as Ta/sub 2/O/sub 5/ and Al/sub 2/O/sub 3/. We found that etching profiles of the metal electrodes are predominantly dependent on etching gases as well as the type of underlying dielectric material.