A novel selective removal process of cobalt silicide

In this paper we study the formation of cobalt silicide on silicon and LP-CVD silicon oxide. The study was carried out on blanket and patterned wafers by the aid of Auger spectroscopy, electrochemical measurements and scanning electron microscopy (SEM). The preparation of pattern wafers follows the conventional process flow using the silicide self-aligned technology for the fabrication of Flash devices. The Auger spectra revealed the formation of the CoSi x phase on silicon and the formation of a ternary Co–Si–O compound on silicon dioxide. The latter, that is responsible of potential electrical shortage between gate and contacts was successfully removed via a novel selective dissolution process, characterized by low cost, low temperature, and a simple formulation chemistry.