Options
Ultrathin ferroic HfO<inf>2</inf>–ZrO<inf>2</inf> superlattice gate stack for advanced transistors
Journal
Nature
ISSN
00280836
Date Issued
2022-04-07
Author(s)
Cheema, Suraj S.
Shanker, Nirmaan
Wang, Li Chen
Hsu, Cheng Hsiang
Hsu, Shang Lin
Liao, Yu Hung
San Jose, Matthew
Gomez, Jorge
Chakraborty, Wriddhi
Li, Wenshen
Bae, Jong Ho
Volkman, Steve K.
Kwon, Daewoong
Rho, Yoonsoo
Pinelli, Gianni
Rastogi, Ravi
Pipitone, Dominick
Stull, Corey
Cook, Matthew
Tyrrell, Brian
Stoica, Vladimir A.
Zhang, Zhan
Freeland, John W.
Tassone, Christopher J.
Mehta, Apurva
Saheli, Ghazal
Thompson, David
Suh, Dong Ik
Koo, Won Tae
Nam, Kab Jin
Jung, Dong Jin
Song, Woo Bin
Lin, Chung Hsun
Nam, Seunggeol
Heo, Jinseong
Parihar, Narendra
Grigoropoulos, Costas P.
Shafer, Padraic
Fay, Patrick
Ramesh, Ramamoorthy
Mahapatra, Souvik
Ciston, Jim
Datta, Suman
Mohamed, Mohamed
Hu, Chenming
Salahuddin, Sayeef
Abstract
With the scaling of lateral dimensions in advanced transistors, an increased gate capacitance is desirable both to retain the control of the gate electrode over the channel and to reduce the operating voltage1. This led to a fundamental change in the gate stack in 2008, the incorporation of high-dielectric-constant HfO2 (ref. 2), which remains the material of choice to date. Here we report HfO2–ZrO2 superlattice heterostructures as a gate stack, stabilized with mixed ferroelectric–antiferroelectric order, directly integrated onto Si transistors, and scaled down to approximately 20 ångströms, the same gate oxide thickness required for high-performance transistors. The overall equivalent oxide thickness in metal–oxide–semiconductor capacitors is equivalent to an effective SiO2 thickness of approximately 6.5 ångströms. Such a low effective oxide thickness and the resulting large capacitance cannot be achieved in conventional HfO2-based high-dielectric-constant gate stacks without scavenging the interfacial SiO2, which has adverse effects on the electron transport and gate leakage current3. Accordingly, our gate stacks, which do not require such scavenging, provide substantially lower leakage current and no mobility degradation. This work demonstrates that ultrathin ferroic HfO2–ZrO2 multilayers, stabilized with competing ferroelectric–antiferroelectric order in the two-nanometre-thickness regime, provide a path towards advanced gate oxide stacks in electronic devices beyond conventional HfO2-based high-dielectric-constant materials.