Multistate Capability Improvement of BEOL Compatible FeFET by Introducing an Al2O3 Interlayer

• Published in: IEEE transactions on electron devices 2023-11, Vol.70 (11), p.5632-5637
• Main Authors: Yu, Shihao, Wang, Qin, Zhang, Yefan, Yang, Peng, Luo, Xiaopeng, Liu, Haijun, Chen, Changlin, Li, Qingjiang, Liu, Sen
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Al₂O₃ interlayer (IL); back-end-of-line (BEOL); Energy consumption; FeFETs; ferroelectric field-effect transistor (FeFET); Ferroelectric films; Ferroelectric materials; Ferroelectricity; Field effect transistors; Grain size; Hf0.5Zr0.5O; Interlayers; Logic gates; multistate performance; Neuromorphic engineering; Performance evaluation; Semiconductor devices; Switches; Synapses
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3309776

The capability of multistate is critical for electronic synapses in neuromorphic computing. In this article, the multistate performance of the ferroelectric field-effect transistors (FeFETs) is investigated by inserting an Al _{\mathbf {{2}}}~\text{O}_{\mathbf {{3}}} interlayer (IL) into Hf _{\mathbf {{0}.{5}}} Zr0.5O2 film. The experimental results of characterization indicate that the grain sizes of the ferroelectric film can be effectively reduced by the Al _{\mathbf {{2}}}~\text{O}_{\mathbf {{3}}} IL. Benefiting from the refined grain sizes, both the proposed ferroelectric capacitor and FeFET show excellent multistate performance and linearity. The benchmark with other emerging synaptic devices demonstrates that the back-end-of-line (BEOL) compatible FeFETs behave noticeable synaptic performances, such as 160 conductance states, low nonlinearity ( \alpha _{\mathbf {p}} = −1.83 and \alpha _{\mathbf {d}} = −1.39), high G_{\mathbf {\textit {max}}} / G_{\mathbf {\textit {min}}} (46.1), and low energy consumption (1.13 pJ).