and diffusion is described in mutually assigned u s application ser no 128 742 dated dec 4 1987 now u s pat no 4 914 500 issued on apr 3 1990 to r liu w t lynch and d s williams which is hereby incorporated by reference basically this procedure in one embodiment involves depositing a metal onto a silicon substrate in the source and drain junction regions typically to maintain junctions shallower than 0 25 u03bcm the deposited material should have a thickness generally in the range 0 01 to 0 05 u03bcm thicknesses less than 0 01 u03bcm yield inadequate silicide formation while thicknesses greater than 0 05 u03bcm lead to excessive junction depth formation of the silicide is accomplished by heating the substrate to a temperature generally in the range 400 u00b0 c to 900 u00b0 c the precise temperature employed depends on the particular material used for example a suitable temperature protocol for cobalt is generally a first treatment in the range 400 u00b0 c to 500 u00b0 c to convert the precursor to the monosilicide followed by a treatment in the range 700 u00b0 c to 800 u00b0 c to convert to the disilicide while temperatures in the range 600 u00b0 c to 900 u00b0 c are typically employed for titanium the duration of the heating should be sufficiently short so that the established dopant profiles throughout the device are.