Selective Oxidation of Titanium While Forming Titanium Silicide at Polysilicon and Diffusions
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
Contact metallurgical techniques to be described in this article allow for the formation of self-aligned titanium silicide at the polysilicon and diffusions on a wafer while providing an etch-stop layer of titanium oxide everywhere else. Advantages to be gained from the disclosed procedures include improved contact resistance, lowered polysilicon and diffusion sheet resistance, and borderless contacts; e.g., a "built-in" etch-stop in the form of titanium oxide prevents unwanted etching of the thick oxide areas on the wafer where contacts are made. No mask is required to this end since the titanium silicide forms in a self-aligned manner where silicon (diffusions or polysilicon) is exposed; likewise, the titanium oxide is self-aligned since it results from oxidizing the titanium remaining in the other areas, e.g.