United States Patent U9]
Farahani et al.
5,612,253 Mar. 18,1997
[li] Patent Number:  Date of Patent:
 METHOD FOR FORMING ORDERED
TITANIUM NITRIDE AND TITANIUM
SILICIDE UPON A SEMICONDUCTOR
WAFER USING A THREE-STEP ANNEAL
 Inventors: M. M. Farahani; Shyam Garg, both of Austin, Tex.
 Assignee: Advanced Micro Devices, Inc., Austin, Tex.
An improved method is provided for fabricating a metallization structure upon a semiconductor wafer. The method performs nitridation upon a sputter-deposited Ti layer over junction regions prior to silicidation thereof. Further, nitridation and silicidation are each performed at controlled amounts within the Ti layer overlying field dielectric regions, also included in the semiconductor wafer. Nitridation and silicidation thereby occur during a three-step anneal process of a previously deposited Ti layer. The three anneal steps are carried forward at separate and distinct temperatures, wherein the first anneal temperature is followed by a second, higher anneal temperature, and wherein the second anneal cycle is followed by a third anneal cycle of higher temperature than the first or second anneal temperatures. The resulting TiN/Ti/TiSi2 tri-layer is optimized having the thickest possible TiN film over the junctions and dielectric regions, and further having excellant adherence of the TiN film to the dielectric.
16 Claims, 6 Drawing Sheets