Optimization of the 4 nm-Thick Hf1–xZrxO2 Film with Low Operating Voltage and High Endurance for Ferroelectric Random Access Memory

IF 4.3 3区 材料科学 Q1 ENGINEERING, ELECTRICAL & ELECTRONIC
Han Sol Park, Seungheon Choi, Kyung Do Kim, Min Kyu Yeom, Suk Hyun Lee, Seung Kyu Ryoo, Cheol Seong Hwang
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Abstract

The integration of ferroelectric-doped HfO2 thin films in advanced memory has been impeded by high coercive fields (EC), requiring high operation voltages. The extremely small feature size of the state-of-the-art memory device requires film thickness <5 nm, causing electrical reliability concerns and inefficient ferroelectric orthorhombic phase formation. This research addresses these challenges by optimizing 4 nm-thick (Hf,Zr)O2 (HZO) thin films to enable low-voltage operation with high reliability. It was noted that such an ultrathin film tends to stabilize the tetragonal phase compared to the more commonly researched 10 nm-thick HZO film due to the smaller grain size of the thinner film. Therefore, the capacitor fabrication conditions were reevaluated to destabilize the tetragonal phase while increasing the desired orthorhombic phase by decreasing the oxygen vacancy (VO) concentration in the film. By adjusting the ozone dose time, Zr ratio, crystallization annealing temperature, and TiN capping electrode thickness, the ferroelectric properties of the 4 nm-thick film were significantly enhanced. The decreased VO concentration also contributed to improving the capacitor reliability. The optimized 4 nm-thick HZO films exhibited outstanding ferroelectric properties, with a double coercive voltage (2 VC) of ∼0.8 V, a double remanent polarization (2Pr) of ∼25 μC/cm2 at ±1 V, and 1011 endurance, satisfying gigabit density ferroelectric random access memory requirements.

Abstract Image

为铁电随机存取存储器优化具有低工作电压和高耐用性的 4 nm 厚 Hf1-xZrxO2 薄膜
在先进存储器中集成铁电掺杂的 HfO2 薄膜一直受到高矫顽力场(EC)的阻碍,需要较高的工作电压。最先进存储器件的特征尺寸极小,要求薄膜厚度为 5 nm,这就造成了电气可靠性问题和铁电正交相形成效率低下的问题。这项研究通过优化 4 nm 厚的 (Hf,Zr)O2 (HZO) 薄膜来应对这些挑战,从而实现低电压运行和高可靠性。研究人员注意到,与更常研究的 10 nm 厚 HZO 薄膜相比,这种超薄薄膜更倾向于稳定四方相,因为更薄的薄膜晶粒尺寸更小。因此,我们对电容器的制造条件进行了重新评估,通过降低薄膜中的氧空位(VO)浓度来破坏四方相的稳定性,同时增加所需的正方相。通过调整臭氧剂量时间、Zr 比率、结晶退火温度和 TiN 封顶电极厚度,4 nm 厚薄膜的铁电特性显著增强。VO 浓度的降低也有助于提高电容器的可靠性。优化后的 4 nm 厚 HZO 薄膜具有出色的铁电特性,其双矫顽电压(2 VC)为 ∼0.8 V,±1 V 时的双剩磁极化(2Pr)为 ∼25 μC/cm2,耐久性为 1011,可满足千兆位密度铁电随机存取存储器的要求。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
7.20
自引率
4.30%
发文量
567
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