Self-aligned CoSi2-formation by ion beam mixing and its application to MOS-devices

Shallow junctions with CoSi₂ as contact metallization were formed using the technique of implantation through metal (ITM). Implantation with boron or arsenic ions was used to perform both mixing of the Co/Si interface and junction doping. CoSi₂ formation and dopant activation was carried out subsequently in a single annealing step (RTA). Low contact resistivities between CoSi₂ and highly doped n⁺ and p⁺Si and shallow junctions were achieved using a thermal treatment of only 750°C, 15 s and 800°C, 10 s for arsenic and boron doped junctions, respectively. Junction depths of 0.1 μm and 0.16 μm below the silicide were obtained for CoSi₂/n⁺ (As)p and CoSi₂/p ⁺ (B)n structures. CBKR structures were used for contact resistance measurements. For CoSi₂/p⁺ contacts a specific contact resistance of ρ_C=3.4*10^-8 Ω cm² was determined. CoSi₂/n⁺ (As)p and CoSi₂/p⁺ (B)n diodes produced by this technique showed leakage current densities of about 3 nA/cm² and 20 nA/cm², respectively. N-channel MOS-transistors with silicided source/drain regions fabricated by ITM showed adequate I-V characteristics