Tunable Dielectric and Thermal Properties of Oxide Dielectrics via Substrate Biasing in Plasma Enhanced Atomic Layer Deposition.,ACS Applied Materials & Interfaces

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Tunable Dielectric and Thermal Properties of Oxide Dielectrics via Substrate Biasing in Plasma Enhanced Atomic Layer Deposition.
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-09-11 , DOI: 10.1021/acsami.0c11086
Yoonjin Kim ₁ , Heungdong Kwon ₂ , Hyun Soo Han _{2,

3} , Hyo Jin K Kim ₂ , Brian S Y Kim ₄ , Byung Chul Lee ₅ , Joohyun Lee ₆ , Mehdi Asheghi ₂ , Fritz B Prinz _{2,

3} , Kenneth E Goodson _{2,

3} , Jongwoo Lim ₇ , Uk Sim ₈ , Woosung Park _{1,

9}

Affiliation

The ability to control the properties of dielectric thin films on demand is of fundamental interest in nanoscale devices. Here, we modulate plasma characteristics at the surface of a substrate to tune both dielectric constant and thermal conductivity of amorphous thin films grown using plasma-enhanced atomic layer deposition. Specifically, we apply a substrate bias ranging from 0 to ∼117 V and demonstrate the systematic tunability of various material parameters of Al₂O₃. As a function of the substrate bias, we find a nonmonotonical evolution of intrinsic properties, including density, dielectric constant, and thermal conductivity. A key observation is that the maximum values in dielectric constant and effective thermal conductivity emerge at different substrate biases. The impact of density on both thermal conductivity and dielectric constant is further examined using a differential effective medium theory and the Clausius–Mossotti model, respectively. We find that the peak value in the dielectric constant deviates from the Clausius–Mossotti model, indicating the change of oxygen fraction in our thin films as a function of substrate bias. This finding suggests that the increased local strength of plasma sheath not only enhances material density but also controls the dynamics of microstructural defect formation beyond what is possible with conventional approaches. Based on our experimental observations and modeling, we further build a phenomenological relation between dielectric constant and thermal conductivity. Our results pave invaluable avenues for optimizing dielectric thin films at the atomic scale for a wide range of applications in nanoelectronics and energy devices.

中文翻译：

通过在等离子体增强的原子层沉积中的衬底偏置来调节氧化物电介质的介电和热性质。

按需控制介电薄膜的性能的能力是纳米级设备的根本利益。在这里，我们调制衬底表面的等离子体特性，以调整使用等离子体增强原子层沉积法生长的非晶薄膜的介电常数和导热系数。具体来说，我们施加的衬底偏压范围为0至117 V，并证明了Al ₂ O ₃的各种材料参数的系统可调性。作为衬底偏置的函数，我们发现固有特性的非单调演变，包括密度，介电常数和导热系数。一个关键的观察结果是，介电常数和有效热导率的最大值出现在不同的衬底偏置下。分别使用差分有效介质理论和Clausius-Mossotti模型进一步研究了密度对导热率和介电常数的影响。我们发现介电常数的峰值偏离了克劳修斯-莫索蒂模型，表明我们薄膜中的氧含量随衬底偏压的变化。这一发现表明，等离子体鞘层局部强度的增加不仅提高了材料密度，而且还控制了微结构缺陷形成的动力学，超出了传统方法的范围。根据我们的实验观察和建模，我们进一步建立了介电常数和热导率之间的现象学关系。我们的结果为在纳米级电子和能源设备中的广泛应用提供了优化原子级介电薄膜的宝贵途径。

更新日期：2020-10-07

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