International Business Machines Corporation
Tunable hardmask for overlayer metrology contrast

Abstract:

A tunable amorphous silicon layer for use with multilayer patterning stacks can be used to maximize transparency and minimize reflections so as to improve overlay metrology contrast. By increasing the hydrogen content in the amorphous silicon layer, the extinction coefficient (k) value and the refractive index (n) value can be decreased to desired values. Methods for improving overlay metrology contrast with the tunable amorphous silicon layer are disclosed.