Ferroelectric Undoped HfOx Capacitor With Symmetric Synaptic for Neural Network Accelerator

Jun-Dao Luo, Yu-Ying Lai, Kuo-Yu Hsiang, Chia-Feng Wu, Yun-Tien Yeh, Hao-Tung Chung, Yi-Shao Li, Kai-Chi Chuang, Wei-Shuo Li, Chun-Yu Liao, Pin-Guang Chen, Kuan-Neng Chen, Min-Hung Lee, Huang-Chung Cheng

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8 Scopus citations


A plasma-based ferroelectric undoped HfOx capacitor is fabricated using plasma-enhanced atomic layer deposition (PE-ALD), and the multilevel characteristics of synaptic behavior are investigated. A gradual ferroelectric phase transition in the material is confirmed by grazing incidence X-ray diffraction (GI-XRD) for different O-2 plasma periods. The metal-ferroelectric-metal (MFM) capacitor presents excellent remnant polarization (P-r) up to 13 mu C/cm(2) and a switching endurance of more than 10(8) cycles. Superior small potentiation/depression nonlinearity (alpha(p)/alpha(d) = -0.08 /-1.66 for voltage modulation stimulation) for synaptic training and almost symmetry training curve ( vertical bar alpha(p) - alpha(d)vertical bar) are obtained. High stability under multilevel operation with five consecutive cycles of alternating potentiation and depression is exhibited without significant polarization variation for each training step (pulse).

Original languageAmerican English
Pages (from-to)1374-1377
Number of pages4
JournalIEEE Transactions on Electron Devices
Issue number3
StatePublished - Mar 2021


  • Ferroelectric
  • multilevel
  • synaptic training
  • undoped HfOx


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