Measuring of low contact resistivities of CoSi2 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 1.6×10²⁰ cm^-3 remained constant up to a depth, which depends on the boron annealing temperature. This depth should be larger than the CoSi₂ penetration depth in Si. Conductance profiling of the silicide indicated an undesired layer on top of the CoSi₂. This upper layer influences contact resistivity. It is shown that the removal of this layer may reduce the contact resistivity down to 3 Ωμm².