Effects of graphene intercalation on dielectric reliability of HfO2 and modulation of effective work function for Ni/Gr/c-HfO2 interfaces: first-principles study

Kehua Zhong,Guigui Xu,Yanmin Yang,Zhigao Huang,Jian-Min Zhang

doi:10.1038/s41598-018-19411-0

Abstract

We have investigated the effects of graphene intercalation on dielectric reliability of HfO2 for Ni/Gr/HfO2 interfaces, and the effects of graphene intercalation and interfacial atom vacancy on the effective work function (EWF) of Ni/Gr/HfO2 interfaces using first-principle calculation based on density functional theory. The calculated results indicate that graphene intercalation can improve dielectric reliability of HfO2 dielectric even for the interfaces having interfacial oxygen vacancy or a small amount carbon vacancy. Moreover, the calculated results indicate that, inserting graphene into Ni/HfO2 interface induces the EWF’s to decline, and controlling interfacial oxygen or carbon vacancy can effectively tune the EWF of Ni/Gr/HfO2 interface. Our work strongly suggests that the use of graphene synthesized into Ni/HfO2 interface is a very effective way to improve the interface quality, and controlling interfacial oxygen or carbon vacancy is also an attractive and promising way for modulating the EWF of Ni/Gr/HfO2 interfaces.

Highlights

Metal gate and high dielectric constant “high-k” gate dielectric are considered essential in continued downscaling of metal-oxide-semiconductor field-effect transistor (MOSFET)[1,2]
Several experimental studies on the work function tuning of metal-graphene stack electrode have been done for metal-graphene-oxide structure[15,16,18]
Misra et al.[18] explored multilayer graphene as metal gate electrode by inserting it between SiO2 dielectric and TiN metal. They found that incorporation of graphene between SiO2 dielectric and TiN metal gave rise to significantly improved dielectric reliability and an effective work function (EWF) tuning of gate electrode up to 0.5 eV by controlling the number of graphene layers

Summary

Introduction

Metal gate and high dielectric constant “high-k” gate dielectric are considered essential in continued downscaling of metal-oxide-semiconductor field-effect transistor (MOSFET)[1,2]. It has been experimentally investigated that the effects of incorporation of graphene on gate dielectric reliability and work function tuning for metal-oxide interface. We used first-principles calculations based on density functional theory (DFT) to investigate the following two aspects: (1) the effects of graphene intercalation on dielectric reliability of HfO2.

Results

Conclusion