Work Function Tunability of Refractory Metal Nitrides by Lanthanum or Aluminum Doping for Advanced CMOS Devices

Author

Wang, Xin Peng ; Lim, Andy Eu-Jin ; Yu, Hong Yu ; Li, Ming-Fu ; Ren, Chi ; Loh, Wei-Yip ; Zhu, Chun Xiang ; Chin, Albert ; Trigg, Alastair David ; Yeo, Yee-Chia ; Biesemans, Serge ; Lo, Guo-Qiang ; Kwong, Dim-Lee

Author_Institution

Nat. Univ. of Singapore, Singapore

Volume

54

Issue

11

fYear

2007

Firstpage

2871

Lastpage

2877

Abstract

A lanthanum (La)-doped HfN is investigated as an n-type metal gate electrode on SiO₂ with tunable work function. The variation of La concentration in (HfinfinLa_1-x)N_y modulates the gate work function from 4.6 to 3.9 eV and remains stable after high-temperature annealing (900degC to 1000degC), which makes it suitable for n-channel MOSFET application. An ultrathin high-fc dielectric layer was formed at the metal/SiO₂ interface due to the (HfinfinLa_1-x)N_y and SiO₂ interaction during annealing. This causes a slight reduction in the effective oxide thickness and improves the tunneling current of the gate dielectric by two to three orders. We also report the tunability of TaN with Al doping, which is suitable for a p-type metal gate work function. Based on our results, several dual-gate integration processes by incorporating lanthanum or aluminum into a refractory metal nitride for CMOS technology are proposed.

Keywords

CMOS integrated circuits; MOSFET; aluminium; hafnium compounds; high-k dielectric thin films; lanthanum; refractories; semiconductor doping; silicon compounds; tantalum compounds; work function; CMOS devices; HfN:La - System; SiO₂ - Interface; TaN:Al - System; aluminum doping; dual-gate integration processes; electron volt energy 4.6 eV to 3.9 eV; lanthanum doping; n-channel MOSFET; n-type metal gate electrode; p-type metal gate work function; refractory metal nitrides; temperature 900 C to 1000 C; ultrathin high-k dielectric layer; work function tunability; Aluminum; Annealing; CMOS process; CMOS technology; Dielectrics; Doping; Electrodes; Lanthanum; MOSFET circuits; Tunneling; $(hbox{Hf}_{x}hbox{La}_{1 - x}){rm N}_{y}$; $(hbox{Ta}_{x}hbox{Al}_{1 - x}){rm N}_{y}$; High-$k$ gate dielectric; MOSFET; metal gate; work function tuning;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/TED.2007.907130

Filename

4367619