Capacitance matching by optimizing the geometry of a ferroelectric HfO2-based gate for voltage amplification

K. T. Chen, K. Y. Hsiang, C. Y. Liao, S. H. Chang, F. C. Hsieh, J. H. Liu, S. H. Chiang, H. Liang, S. T. Chang, M. H. Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The voltage amplification of a ferroelectric layer was studied for advanced complementary metal–oxide–semiconductor (CMOS) applications. To match the capacitance for negative-capacitance field-effect transistors (NC-FETs), a method of adjusting the MOS capacitance is proposed by optimizing the width (W) and height/depth (H) in two types of ferroelectric gate-stack 2D metal-oxide semiconductor capacitor (MOSCAP) structures: a fin-like structure and a trench structure. The capacitance of the semiconductor was modeled to match that of the ferroelectric films to obtain hysteresis-free operation (ΔVT = VT, for –VT,rev ~ 0) and achieve voltage amplification (AV). The optimized conditions are found to be H = 19.3 nm and 24.3 nm to achieve the criterion with AV > 50 for the fin-like and trench structure, respectively. Subsequently, the structure was extended to a three-dimensional (3D) fin-shaped field-effect transistor (FinFET) to evaluate the effects of varying geometrical parameters such as the fin spacing (FS). Tuning FS can not only enhance the on-current but also decrease the subthreshold swing in the off-current region. For the FET, the use of the optimum FS value of 30 nm helps the FinFETs achieve capacitance matching with AV > 30. The subthreshold swing of the NC-FinFET is improved by about 47% for HFinFET/WFinFET ~ 3 and Fs/HFinFET ~ 1.2 as compared with the conventional FinFET. The concept of coupling the polarized Hf-based oxide in NC-FETs that is demonstrated to be feasible herein is thus practicable using current CMOS architectures.

Original languageEnglish
Pages (from-to)1209-1215
Number of pages7
JournalJournal of Computational Electronics
Issue number3
Publication statusPublished - 2021 Jun


  • Capacitance matching
  • FinFET
  • Negative capacitance (NC)
  • Optoelectronic
  • Steep switch

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Modelling and Simulation
  • Electrical and Electronic Engineering


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