EVALUATION OF LATERAL DIFFUSION FACTOR IN SILICON FROM SUBTHRESHOLD CURRENT IN SHORT-CHANNEL VERTICAL SIT TEST STRUCTURE

A new measurement method for the evaluation of the lateral diffusion f actor of deep implanted regions in low-doped material is proposed. The method is based on measurements of the subthreshold current versus dr ain voltage in vertical static induction transistor (SIT) devices. The subthreshold current is very sensitive to SIT channel width and hence to lateral diffusion of the gate regions, as shown by two-dimensional numerical analysis. Experimental results obtained by fabricating test structures with different Boron doses and the same drive-in treatment allow us to evaluate for a typical drive-in process a lateral diffusi on factor of 64%.