Ta/TiN midgap full-metal single gate fabrication using combined chlorine-based plasma and highly selective chemical metal etching for decananometer CMOS technology

High permittivity dielectric and metal gate are now the most demanded in advanced CMOS technology to overcome conventional polysilicon gate structure drawbacks. However, existing metal gate fabrication approaches are not capable to meet all the demands in terms of material engineering or fabrication process. In this study, we present a two-step dry and wet etching strategy for the integration of tantalum and titanium nitride full-metal single gate, which offers a perfect vertical, roughness-free sidewall and an ultra high metal/dielectric etch rate selectivity.

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► We report a metal gate fabrication process with combined dry/wet etching strategy.
► SiN hard-mask significantly improves pattern transfer and line edge roughness.
► We optimized RIE and tune wet solution to a soft landing on the gate dielectric.
► Vertical, roughness-free gate sidewall and ultra high selectivity are achieved.