Simultaneous formation of a shallow silicon p-n junction and a shallow silicide/silicon ohmic contact by an ion implantation technique

An ion implantation technique has been developed for the simultaneous formation of a shallow Si p-n junction and a shallow silicide/Si ohmic contact. A p-Si substrate is coated with a thin layer of W, then with alternating layers of Si and W. Bombardment of the coated substrate with As+ ions causes formation of WSi2 from the W and Si layers, dispersion of contaminant atoms at the interface between the first W layer and the substrate, and implantation of As atoms in the substrate. Subsequent thermal annealing produces a shallow WSi2/Si ohmic contact and simultaneously activates the implanted As donors to form a shallow p-n junction located directly below the contact. Mesa diodes with good junction characteristics have been fabricated by using this technique.