Shallow junctions by out-diffusion from arsenic implanted polysilicon.

We describe, in separate sections, contact resistance, reverse bias diode leakage and physical analysis (SIMS, TEM and RBS) data from shallow n sup + /p junctions made by implanting various doses of As into polysilicon and outdiffusing, at various temperature/time conditions, into the underlying 100> Si. The polysilicon is cobalt disilicided to provide for subsequent metallization consisting of selective electroless plated cobalt/sputtered aluminum. The Al/Co/CoSi (As) poly-Si/mono-Si contact resistivity is ~ 0.1 micro ohm -cm sup 2 for conditions giving good junction quality. These conditions are 7E15 As; 950 degrees for 30 min giving X sub j ~ 1200 angstroms and reverse bias diode leakage (~ 10V) of ~ 10 nA/cm sup 2. Most (~ 90%) of the implant redistributes, relatively uniformly, in the polysilicon.