(A) Study on the performance and reliability evaluation of CMOS ring oscillator

Abstract

Nowdays, CMOS circuits are widely used today in CMOS applications such as CPUs, microprocessor designs, flash memory chip designs, and ASICs. As CMOS technology node shrinks down continuously, the oxide thickness becomes smaller and the operating voltage of CMOS circuits becomes smaller, too. As a result, the BTI problem becomes a bigger issue than the HCI problem in CMOS circuit operation. In this work, for the 74 nm complementary metal oxide semiconductor (CMOS) ring oscillator (RO) which is one of the CMOS analog circuits, the effect of Fowler-Nordheim (FN) stress and Bias Temperature Instability (BTI) stress on the performance and reliability evaluation of the CMOS RO is investigated. Specifically, with the aid of TCAD simulation based on the measured data of the fabricated device, the performance of CMOS RO due to the degradation due to the traps and fixed charges in the simulation is investigated. Also, The reliability about the FN stress and BTI stress of the CMOS RO with different two widths is compared and predicted through modeling. This study suggests a guideline for the fabrication of CMOS circuits such as CMOS RO degradation with the consideration of the traps and fixed charges.