An Investigation for the Negative-Bias Temperature Instability Aware CMOS Logic

Abstract

Scaling of the dimensions of semiconductor device plays a very important role in the advancement of very large-scale integration (VLSI) technology. There are many advantages of scaling in VLSI technology such as increment in the speed of the device and less area requirement of the device. Aggressive device scaling causes some limitations in the form of short channel effects which produce large leakage current. Large leakage current harms the characteristics of the device and affects the reliability of the device. The most important and popular reliability issue in deep submicron (DSM) regime is negative-bias temperature instability (NBTI). NBTI effect increases the threshold voltage of p-channel metal oxide semiconductor (PMOS) device over the time and affects the different characteristics of the device. As a result, circuit delay exceeds the design specification and there may be timing violations or logic failure. Different performance parameters are observed under NBTI effect for different logic gates. This paper presents an impact of NBTI at 22nm Berkeley short-channel IGFET model4 (BSIM4) predictive technology model (PTM) for complementary metal oxide semiconductor (CMOS) logic gates. Reliability simulations are utilised to evaluate the amount of gradual damage in PMOS device due to NBTI effect. The impact of NBTI degradation is checked for various CMOS logic gates using Mentor Graphics’s Eldo circuit simulator. Output voltage and drain current are reducing over the time under NBTI effect. NBTI degradation increases the threshold voltage of PMOS device over the time and affects the different characteristics of the device.