柔性云母基底上高性能Hf0.5Zr0.5O2铁电薄膜制备与性能研究

Preparation and Research of High-performance Hf0.5Zr0.5O2 Ferroelectric thin Films on Flexible Mica Substrates

  • 摘要: 铪基铁电薄膜与传统的互补金属氧化物半导体(CMOS)加工工艺兼容,且在超薄膜厚(低至1 nm)下仍具有良好的铁电性,用其制作的柔性铁电存储器将为柔性电子系统注入新的活力。然而,剩余极化强度不高且器件可靠性不佳是铪锆氧(HZO)基柔性铁电存储器普遍面临的问题。本研究在云母衬底上沉积了氧化铝缓冲层,制备了W/TiN/HZO/TiN/Al2O3/Mica结构的铁电存储器。该柔性铁电存储器表现出免“唤醒”特性,其二倍剩余极化强度高达44 μC/cm2,可耐受至少109次±3 MV/cm的反复写擦。在弯曲半径低至3 mm以及经历高达5000次弯曲的情况下,器件的剩余极化强度、矫顽场均未衰减,体现出良好的弯曲可靠性。进一步研究表明,氧化铝缓冲层能有效解决膜层之间应力失配所导致的膜层开裂问题,此外,HZO中正交相存在且具有较大占比,这些可能是决定器件剩余极化强度高和可靠性好的重要因素。

     

    Abstract: Hafnium-based ferroelectric films are compatible with conventional CMOS processing and have good ferroelectric properties at ultra-thin film with thicknesses down to 1 nm. Flexible hafnium-based ferroelectric memories will breathe new life into flexible electronic systems. However, low remnant polarization and poor endurances are common problems faced by hafnium zirconium oxide (HZO) flexible ferroelectric memories. In this study, a ferroelectric memory with W/TiN/HZO/TiN/Al2O3/Mica structure was prepared after depositing an alumina buffer layer on the mica substrate. The flexible ferroelectric memory exhibits ‘wake-up’ free feature, with a double remnant polarization as high as 44 μC/cm2, and can withstand repeated writing and erasing of at least 109 times under ±3 MV/cm. With bending radius as low as 3 mm and up to 5,000 bending cycles, both the remnant polarization and coercive field of the device do not decay, demonstrating a good bending reliability. Further studies show that the alumina buffer layer can effectively solve the cracking problem caused by the stress mismatch between the layers. Moreover, the orthorhombic phase in HZO exists and accounts for a large proportion. These may be important factors in determining the high polarization and high device reliability.

     

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