Defect density evaluation in a high-k MOSFET gate stack combining experimental and modeling methods

We report on a methodology to assist fabrication process development using a case study of high thermal budget (HTB) and low thermal budget (LTB) fabrication flows for high-k/metal gate stacks in n-MOSFETs. This methodology is supported by simulations that self-consistently extract defect characteristics by simultaneously considering a set of electrical measurement data, specifically stress-induced leakage current (SILC), threshold voltage shift (PBTI), and multi-frequency charge-pumping (MFCP). The contributions of pre-existing and stress-induced defects in SiO₂/HfO₂ gate stacks on device performance are examined. Information on defect distributions, extracted in the as-fabricated and post-stress HTB and LTB devices, allow understanding their dependence on the fabrication process, which can provide guidelines for the process optimization.