Selective removal of rare earth comprising materials in a semiconductor device

摘要

The present invention discloses a method for the selective removal of rare earth based high-k materials such as rare earth scandate high-k materials (e.g. DyScO 3 ) over silicon or silicon dioxide. As an example Dy and Sc comprising high-k materials are used as a high-k material in gate stacks of a semiconductor device. The selective removal and etch of this high-k material is very difficult since Dy and Sc (and their oxides) are difficult to etch. The etching could however be easily stopped on them. The Dy and Sc chlorides are not volatile, but they are water soluble. This behavior makes it possible that the surface layer of Dy and Sc comprising high-k materials gets chlorinated during exposure to the Cl-containing plasma and can be removed after etch by a water rinse.