Study on different failure mechanisms of MOSFET caused by different oxide defects in 14 nm FinFET IC

Abstract

With the advent of FinFET technology, especially in the application of 14 nm and above nodes, the front-end-of-line (FEOL) defects at the transistor level have become increasingly significant. These minute FEOL defects have a critical impact on the yield and reliability of the ultimate chipset. This paper focuses on two types of FEOL defects identified in 14 nm FinFET technology. The research shows that both of these FEOL defects can lead to leakage in MOSFETs. We have conducted an in-depth analysis of the distinct failure mechanisms of these two defects and their potential formation causes. It is expected to help wafer factories achieve effective improvements. The study indicates that these two failure modes might be triggered by oxide defects in different steps of the FEOL process flow. Specifically, in one case, dielectric breakdown-induced epitaxy (DBIE) causes NMOS gate leakage, which might be ascribed to the presence of defects in the bottom interface layer (BIL) of the oxide. In another instance, PMOS leakage caused by germanium bridge defects might result from oxide defects as the etch stop layer (ESL) and the influence of subsequent process steps on the defects. This research provides an essential guiding direction for wafer factories to optimize the manufacturing process of 14 nm FinFET products and improve yield and quality. At the same time, this study also offers a valuable reference basis for the failure analysis of FinFET devices.