dc.description.abstract | With the scaling of IC devices on Moore’s Law extension, the contact sheet resistance reduction is crucial on IC device fabrication. Ion implantation with additives elements for material modification and structural crystallization is one of the most critical methods for contact resistance reduction. It is also being widely used at semiconductor manufacturing in recent decades.
This dissertation systematically investigated the formation behaviors and microstructures of Nickel silicide with ion implantation or deposited the additive elements for contact sheet resistance reduction to addressed the CMOS transistors scaling challenges as well as device performance improvement.
Firstly, the experimental results showed the thermal stability of Nickel silicide was improved by adding Aluminum (Al) into Nickel silicides on Silicon (Si) (001), and the phase transformation of Ni2Si to NiSi was also retarded by adding Al atoms, it was also significantly speeds up the NiSi2-xAlx formation during annealing. The behavior of Nickel silicide phase transformation is strongly depending on the Al concentration of the initial Ni1-xAlx alloys. Compared to the Ni0.95Pt0.05/Si and Ni0.95Al0.05/Si system, the Ni0.91Al0.09/Si sample exhibits remarkably enhanced thermal stability, even after high temperature annealing for 1000 second. The relationship between microstructures, electrical property, and thermal stability of Ni silicide is discussed to elucidate the role of Al during the Ni1-xAlx alloy silicidation. This work demonstrated the Ni1-xAlx alloy silicide thermal stability would be a promising candidate as source/drain (S/D) contacts material in advanced complementary metal–oxide semiconductor (CMOS) devices.
Secondly, the experiment is systematically investigated the effects of Ti-doped Nikel silicide on different substrates during the Nickel silicidation, especially on the Pre-amorphous Ion Implantation Si substrate with Xenon (Xe) ion implantation. The TEM, GIXRD, XPS, and Raman were used for metrology analysis. Due to lower diffusion rate and lower solubility of Titanium atoms in Ni0.9Ti0.1 on both Si and pre-amorphous ion implant Si (PAI-Si) substrates, it led to the NiSi2 formation. The formation of NiSi2, will reduce the free energy and force the Titanium atoms accumulated at the interface, then transformed into TiO2 at higher temperature to prevent the Nickle diffuses into the substrates. Especially on PAI-Si, the implanted Xe atoms will postpones the formation of NiSi2 and reduce the free energy, force the Titanium accumulated at the crystalline/ amorphous interface as diffusion barrier layer. Thus, in PAI Si substrate, the Titanium Nickel silicide will increase the formation temperature of NiSi2, which could increase the thermal stability, but also reduce the Schottky Barrier Height for contact resistance reduction to boost the CMOS devices performance. | en_US |