April 22 - 26, 2024
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May 7 - 9, 2024 (Virtual)
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2024 MRS Spring Meeting & Exhibit
EL07.09.06

Characterizing Negative Capacitance in Ultrathin Ferroelectric HfO2-ZrO2 Towards Energy-Efficient Advanced Transistors

When and Where

Apr 25, 2024
3:30pm - 3:45pm
Room 342, Level 3, Summit

Presenter(s)

Co-Author(s)

Qinyuan Xue1,Nirmaan Shanker1,Suraj Cheema1,Sayeef Salahuddin1,2

University of California, Berkeley1,Lawrence Berkeley National Laboratory2

Abstract

Qinyuan Xue1,Nirmaan Shanker1,Suraj Cheema1,Sayeef Salahuddin1,2

University of California, Berkeley1,Lawrence Berkeley National Laboratory2
Negative capacitance (NC) [1] has emerged as a promising solution to overcome fundamental energy-efficiency limits in conventional electronics, in which internal ferroelectric order within the gate stack of a field-effect transistor can enable low-power operation. In particular, by swapping the conventional high-κ dielectric with a negative-κ ferroelectric gate stack, enhanced gate capacitance, i.e. lower equivalent oxide thickness (EOT), can be realized in advanced Si transistors, resulting in key performance benefits in transistors compared to established semiconductor foundry benchmarks [2-3]. We have previously stabilized NC in sub-2-nm HfO2-ZrO2 heterostructures [2-3], where we observe a capacitance enhancement, definitive proof of NC stabilization, over the SiO2 interlayer [2-3] via small-signal capacitance measurements. However, the full internal polarization-electric field (P-EFE) relation was not extracted for these NC gate oxides.
In this work, ultrafast pulsed I-V measurements are used to map the ‘S’-shaped P-EFE relation in various ultrathin (sub-2-nm) HfO2-ZrO2 NC gate stacks towards realizing both EOT and physical thickness scaling for power- and dimensional-scaling, respectively. The extracted P-EFE relation shows a negative dP/dEFE region, a clear signature of NC stabilization. Additionally, by integrating the P-EFE relation, the characteristic ferroelectric double-well energy landscape was extracted and modelled with a Landau-Ginzburg-Devonshire framework. Both P-EFE and energy landscapes were then used to quantify the degree of NC stabilization across the various gate stacks. Overall, this work further confirms NC stabilization in ultrathin HfO2-ZrO2 heterostructures via large-signal pulsed I-V measurements (as opposed to small-signal capacitance measurements) and provides a methodology to quantify the degree of NC stabilization.
[1] S Salahuddin & S Datta. “Use of Negative Capacitance to Provide Voltage Amplification for Low Power Nanoscale Devices.” Nano Lett. 8, 405–410
[2] S Cheema et al. “Ultrathin ferroic HfO2–ZrO2 superlattice gate stack for advanced transistors.” Nature 604, 65 (2022).
[3] N Shanker et al. “Ultralow equivalent oxide thickness via one nanometer ferroelectric negative capacitance.” In preparation.

Keywords

ferroelectricity

Symposium Organizers

John Heron, University of Michigan
Morgan Trassin, ETH Zurich
Ruijuan Xu, North Carolina State University
Di Yi, Tsinghua University

Symposium Support

Gold
ADNANOTEK CORP.

Bronze
Arrayed Materials (China) Co., Ltd.
NBM Design, Inc.

Session Chairs

Lauren Garten
Aileen Luo

In this Session