Patent ID: 6774023
Filing Date: 2004-08-10
Classification: H01L

Abstract:
A method for fabricating a continuous layer of titanium silicide with prescribed sheet resistance essentially throughout on the surface of a polycrystalline silicon layer formed on an oxide layer within a semiconductor device, said titanium silicide exhibiting high-temperature instability only above 814Â° C., said method comprising the successive steps of:forming said oxide layer on a substrate; forming said polycrystalline silicon layer on said oxide layer; depositing a layer of tantalum on said polycrystalline silicon layer; depositing a layer of titanium on said layer of tantalum; rapidly annealing the structure resulting from the foregoing steps at temperature below 814Â° C., long enough to result in the conversion of said layer of tantalum to a layer of tantalum silicide and to result in the conversion of said layer of titanium to a layer of titanium silicide; and thereafter purposely subjecting the structure resulting from said annealing for at least several minutes to elevated temperature above 814Â° C., said layer of tantalum silicide forestalling the occurrence of discontinuities in said layer of titanium silicide owing to said elevated temperature, which discontinuities would occur if said layer of titanium silicide directly adjoined said polycrystalline silicon layer and would raise said sheet resistance undesirably above said prescribed value.