Specific Contact Resistivity Improvement by As Preamorphization Implantation for Ti-Based Ohmic Contacts on n+-Si

As preamorphization implant (PAI) for Ti-based ohmic contacts on n⁺-Si is explored in this article. With As implantation at 3 keV/5 × 10¹³ cm^-2, the specific contact resistivity (ρ_c) of TiSi_x on 1.4 × 10²⁰ cm^-3 P-doped (Nd) n+-Si is significantly reduced by ~33.8%, down to ~2.33 × 10^-8-cm^-2. This ρ_c improvement is a result of manipulation between the reduction of effective Schottky barrier height to electrons (φ_bn,eff) and the retardation of Ti silicidation, which are both strongly correlated with As segregation. In comparison with the widely adopted Ge PAI, As PAI shows superior performance for nMOS contact engineering, featuring with lower ρ_c and φ_bn,eff as well as better thermal stability.