Etchants and Etching Processes for High k Gate Dielectric
Original Publication Date: 2002-Aug-05
Included in the Prior Art Database: 2002-Aug-05
Integration of high k gate dielectric materials into a standard CMOS flow requires that a wet etching approach be developed to avoid plasma damage during a dry etch. The etchants and etching processes for two kinds of high k gate dielectric materials, lanthanum aluminate and lanthanum aluminum oxynitride, are proposed. In the proposed method, the mixed solution of hydrochloric acid/phosphoric acid with deionized water and/or hydro peroxide can effectively remove lanthanum aluminate and lanthanum aluminum oxynitride films at high etch rates up to 5nm/min. The films can be completely removed resulting in a very smooth surface. The proposed technique can be used in fabrication flows where lanthanum aluminate and lanthanum aluminum oxynitride are used as high k gate dielectrics for logic, memory, and analog products.