ADVANCED SOURCE AND DRAIN CONTACT ENGINEERING FOR FIELD-EFFECT TRANSISTORS

Abstract

In this thesis, advanced source/drain contacts are explored for future p-channel transistors beyond 7 nm nodes. First, incorporation of Sn into Ge is proposed to lower specific contact resistivity for metal/p-type GeSn contacts. Moreover, segregation of Sn and Ga to the surface of GeSn (Seg. p+-GeSn) is exploited to reduce specific contact resistivity to 4.4×10-10 Ohm-cm2, which is the lowest specific contact resistivity for any non-laser-annealed contacts. In addition, highly accurate characterization methodologies are developed for the assessment of specific contact resistivity. First, an ETL model is developed to extend Nano-TLM for characterizing alloyed contacts, where TLM-based methods fails. Second, the parasitic metal resistance in TLM in quantitatively analyzed and eliminated. Finally, a universal TLM, featuring eliminated parasitic metal resistance, simple fabrication process, sub-10-10 Ohm-cm2 resolution, and robustness for both alloyed and non-alloyed contacts, is developed for fast and highly accurate extraction of specific contact resistivity.