Charge redistribution to reduce contact resistivity in NiSi/Si system through interface modification: A first-principles study

The metal–semiconductor contact resistivity has become a severe challenge for three-dimensional (3D) integration. In this work, starting from the physical origin, we propose that the charge redistribution is an effective strategy for decreasing Schottky barrier height (SBH), subsequently leading to a reduction in contact resistivity. Guided by this perspective, first-principles calculations are utilized to investigate the effect of a series of metal dopants on the SBH in the NiSi/Si system. The ΦBe values of NiSi/Si can be reduced to 0.27, 0.28, and 0.22 eV in Sc, Ti, and Zr doped systems, respectively. Especially for the Zr dopant, it can achieve ultra-low contact resistivity of 2.30 × 10−9 Ω cm2, which can be ascribed to the dominant charge redistribution effect. In contrast, high electronegativity dopants like Au and Ir increase ΦBe. Dopant diffusion and concentration effects are also examined, demonstrating the feasibility of this approach. This work provides a useful theoretical guidance in reducing contact resistivity for 3D integration.