Method for enhanced uni-directional diffusion of metal and subsequent silicide formation

Abstract

The present invention provides a method for enhancing uni-directional diffusion of a metal during silicidation by using a metal-containing silicon alloy in conjunction with a first anneal in which two distinct thermal cycles are performed. The first thermal cycle of the first anneal is performed at a temperature that is capable of enhancing the uni-directional diffusion of metal, e.g., Co and/or Ni, into a Si-containing layer. The first thermal cycle causes an amorphous metal-containing silicide to form. The second thermal cycle is performed at a temperature that converts the amorphous metal-containing silicide into a crystallized metal rich silicide that is substantially non-etchable as compared to the metal-containing silicon alloy layer or a pure metal-containing layer. Following the first anneal, a selective etch is performed to remove any unreacted metal-containing alloy layer from the structure. A second anneal is performed to convert the metal rich silicide phase formed by the two thermal cycles of the first anneal into a metal silicide phase that is in its lowest resistance phase. A metal silicide is provided whose thickness is self-limiting.

1 . A semiconductor structure comprising 
 a silicon-containing material having regions in which a metal silicide is located thereon, said metal silicide is in its lowest resistance phase and has a thickness from about 14 to about 25 nm, whereby said metal silicide is not located atop isolation trench regions thereby reducing leakage within the structure.    
   
   
       2 . The semiconductor structure of  claim 1  wherein said metal silicide is cobalt disilicide or nickel monosilicide.  
   
   
       3 . The semiconductor structure of  claim 1  wherein said metal silicide is continuous containing no embedded oxide therein.  
   
   
       4 . The semiconductor structure of  claim 1  wherein said Si-containing material comprises a substrate, a gate electrode or both.  
   
   
       5 . The semiconductor structure of  claim 1  wherein said Si-containing material comprises single crystal Si, polycrystalline Si, SiGe, amorphous Si, silicon-on-insulator (SOI) or silicon germanium-on-insulator (SGOI).