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H. Kraus, F. Kovacs, J. Snow, M. Claes, V. Paraschiv, R. Vos, P. W. Mertens, S. De Gendt, M. Heyns, L. Archer
SEZ AG, Draubodenweg 29, Villach Austria IMEC, Kapeldreef 75, Leuven, Belgium

ABSTRACT

Selective removal of Hf-based high-k material from the source and drain areas is one of the challenges for the integration of these materials in the front-end-of-line (FEOL) process flow. On the one hand, they are usually very difficult to etch, and on the other hand, just a small loss of oxide and silicon can be tolerated. A novel dry-enabled wet etch solution is presented that can very effectively, and with high selectivity, remove unwanted high-k dielectric. This approach leads to minimal Si recess and oxide loss. Furthermore, the application of this etch is compared for both immersion and single-wafer approaches and it shows that a single wafer solution provides a more selective alternative to immersion. Etch rates and selectivities are presented in detail and are further supported with TEM and electrical data.