Description
The benefit of OI technology to mitigate the increase in sheet resistance (R_sh) with decreasing junction depth (X_J) for ultra-shallow-junctions (USJs) relevant for deep-sub-micron planar CMOS transistors is assessed through the fabrication of R_sh test structures, electrical characterization, and technology computer-aided design (TCAD) simulations. Experimental and secondary ion mass spectroscopy (SIMS) analyses indicate that OI technology can facilitate low-resistivity USJ formation by reducing R_sh and X_J, due to retarded transient-enhanced-diffusion (TED) effects and enhanced dopant retention during post-implantation thermal annealing. It is also shown that a low-temperature-oxide (LTO) capping can increase R_sh unfavorably due to lower dopant activation levels, which can be alleviated by OI technology.
This dissertation extends the evaluation of OI technology to advanced FinFET technology, targeting 7/8-nm low power technology node. A bulk-Si FinFET design comprising a super-steep retrograde (SSR) fin channel doping profile achievable with OI technology is studied by three-dimensional (3-D) TCAD simulations. As compared with the conventional bulk-Si (control) FinFET design with a heavily-doped fin channel doping profile, SSR FinFETs can achieve higher I_on/I_off ratios and reduce the sensitivity of device performance to variations due to the lightly doped fin channel. As compared with the SOI FinFET design, SSR FinFETs can achieve similarly low V_DD,min for 6T-SRAM cell yield estimation. Both SSR and SOI design can provide for as much as 100 mV reduction in V_DD,min compared with the control FinFET design. Overall, the SSR FinFET design that can be achieved with OI technology is demonstrated to be a cheaper alternative to the SOI FinFET technology for extending CMOS scaling beyond the 10-nm node.
Finally, this dissertation investigates the benefits of OI technology for reducing the Schottky barrier height (Phi_Bp) of a Pt/Ti/p-type Si metal-semiconductor (M/S) contact, which can be expected to help reduce the specific contact resistivity for a p-type silicon contact. Electrical measurements of back-to-back Schottky diodes, SIMS, and X-ray photoelectron spectroscopy (XPS) show that the reduction in Phi_Bp is associated with enhanced Ti 2p and Si 2p core energy level shifts. OI technology is shown to favor low-Phi_Bp Pt monosilicide formation during forming gas anneal (FGA) by suppressing the grain boundary enhanced diffusion of Pt atoms into the crystalline Si substrate.