The use of refractory metal and electron-beam sintering to reduce contact resistance for VLSI

Abstract

Low contact resistance for metal on silicon is particularly important for VLSI where contact dimensions become ≤1 µm. This paper reports on e-beam sintering of refractory metal contacts on implanted n+- and p+-silicon layers. With this technique, we have obtained contact resistivities as low as 1.5 × 10-7Ω. cm2and 1.2 × 10-7Ω . cm2for n+and p+contacts, respectively. These values are the lowest contact resistivities which have been achieved experimentally to date. We found no measurable metal-silicon interdiffusion when e-beam sintering was used. Electron-beam-induced MOS damage, including neutral traps, can be removed by a forming gas anneal.