Characteristics of nickel silicide thin films fabricated by ultraviolet nanosecond laser annealing

Ultraviolet nanosecond laser annealing (UV-NLA)-based silicidation is a promising technology for reducing the thermal budget in the fabrication of highly integrated complementary metal–oxide–semiconductor (CMOS) devices. Here, we demonstrated three reaction pathways for nickel silicide formation (solid-phase reaction (SPR), melting and regrowth after SPR, and liquid-phase reaction (LPR)) based on the applied laser energy densities using KrF pulsed laser in a Ni/p-Si substrate structure. Subsequently, we compared the characteristics of the nickel silicide films including surface roughness, crystal structures, interfacial qualities, chemical composition distributions, and electrical properties. Our results confirmed that the characteristics of the nickel silicide films varied depending on the silicide formation mechanisms. SPR-induced films exhibited NiSi and NiSi₂ mixed polycrystalline structures with flat interfaces and uniform composition distributed along the interfaces regardless of the melting phenomenon during silicidation. In contrast, LPR-induced nickel silicide films exhibited interfacial instabilities and cellular structures caused by constitutional supercooling. Compared with the SPR-induced polycrystalline nickel silicide films, the LPR-induced one exhibited an effective-electron Schottky barrier height (SBH) that was 0.03 eV lower due to the recreated interface structure containing locally coherent NiSi₂. Our results provide crucial insights into implementing a comprehensive approach to silicidation through UV-NLA, presenting a promising next-generation contact process.