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arXiv 2101.04886cond-mat.mtrl-sci
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无唤醒Hf0.5Zr 0.5O2铁电薄膜的大剩余极化

Large remnant polarization in a wake-up free Hf0.5Zr0.5O2 ferroelectric film

Alireza Kashir, Hyung Woo Kim, Seungyeol Oh, Hyunsang Hwang

摘要:

通过调节臭氧脉冲宽度、退火工艺和金属/绝缘体界面,获得了迄今为止具有最高剩余极化(Pr)值的无唤醒Hf0.5Zr0.5O2(HZO)铁电薄膜.在HZO薄膜的原子层沉积过程中的臭氧剂量似乎是一个重要的参数,在抑制驱动唤醒效应的机制。具有相对低的热膨胀系数的钨盖电极能够诱导面内拉伸应变,这在退火工艺的冷却步骤期间增加斜方晶相的形成,同时减少单斜晶相的形成。因此,提高退火温度TA,随后快速冷却至室温导致2 Pr值显著增加(64 uC/cm 2)。然而,漏电流显著增加,这会影响金属-绝缘体-金属(MIM)器件的性能。为了减少漏电流,同时保持热退火过程中的机械应力,10 nm的Pt层之间的W/HZO底部界面插入。这导致漏电流降低约20倍,而2 Pr值几乎保持恒定(约60 uC/cm 2)。在Pt/HZO界面处的势垒高度的增加相比,与通过引入Pt/HZO界面的界面氧化物(WOx)的形成的抑制相耦合的W/HZO界面用于降低漏电流。

英文摘要:

A wake-up free Hf0.5Zr0.5O2 (HZO) ferroelectric film with the highest remnant polarization (Pr) value to-date was achieved through tuning of the ozone pulse duration, the annealing process, and the metal/insulator interface. The ozone dosage during the atomic layer deposition of HZO films appears to be a crucial parameter in suppressing the mechanisms driving the wake-up effect. A tungsten capping electrode with a relatively low thermal expansion coefficient enables the induction of an in-plane tensile strain, which increases the formation of the orthorhombic phase while decreasing the formation of the monoclinic phase during the cooling step of the annealing process. Therefore, increasing the annealing temperature TA followed by rapid cooling to room temperature resulted in a substantial increase in the 2Pr value (64 uC/cm2). However, the leakage current increased considerably, which can affect the performance of metal-insulator-metal (MIM) devices. To reduce the leakage current while maintaining the mechanical stress during thermal annealing, a 10 nm Pt layer was inserted between the W/HZO bottom interface. This resulted in a ~ 20-fold decrease in the leakage current while the 2Pr value remained almost constant (~ 60 uC/cm2). The increase in barrier height at the Pt/HZO interface compared to that of the W/HZO interface coupled with the suppression of the formation of interfacial oxides (WOx) by the introduction of a Pt/HZO interface serves to decrease the leakage current.

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