A Novel Method to Reduce Specific Contact Resistivity of TiSix/n+-Si Contacts by Employing an In-Situ Steam Generation Oxidation Prior to Ti Silicidation

Jianfeng Gao,Dan Zhang,Yaodong Liu,Jinbiao Liu,Jun Luo,Dapeng Chen,Junfeng Li,Yongliang Li,Wenwu Wang,Jing Xu,Menghua Li,Chao Zhao,Xuebing Zhou,Xianglie Sun,Tianchun Ye

doi:10.1109/led.2021.3081701

Abstract

Due to extremely tight Contacted Poly Pitch (CPP) in sub-10 nm nodes, specific contact resistivity ( ρ c ) has become the main concern for further improvement of transistor performance. Both the reduction of Schottky barrier heights (SBHs) and the enhancement of surface dopant concentration (N s ) are considered as the most effective approaches to reduce ρ c . In this work, a novel in-situ steam generation (ISSG) oxidation process prior to Ti silicidation is proposed to achieve an enhanced N s value, thanks to the segregation of P at the surface of n + -Si. Refined Transmission Line Model (RTLM) structures were fabricated to extract the ρ c accurately and reliably. The dopant redistribution of P was characterized by both secondary ion mass spectrometry (SIMS) and spreading resistance probe (SRP). Compared to control samples, the ρ c value for samples with 4 nm ISSG SiO 2 is reduced from 2.91×10 -8 to 1.90×10 -8 Ω-cm 2 , and this is attributed to the enhancement of N s value.

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