Measuring of low contact resistivities of CoSi/sub 2/ on shallow B-junctions

The active boron concentration, which affects contact resistivity, was profiled by stepwise four-point probing and Si reactive ion etching. The maximum concentration of 1.6/spl times/10/sup 20/ cm/sup -3/ remained constant up to a depth, which depends on the boron annealing temperature. This depth should be larger than the CoSi/sub 2/ penetration depth in Si. Conductance profiling of the silicide indicated an undesired layer on top of the CoSi/sub 2/. This upper layer influences contact resistivity. It is shown that the removal of this layer may reduce the contact resistivity down to 3 /spl Omega//spl mu/m/sup 2/.