Density and size effects on the thermal conductivity of atomic layer deposited TiO2 and Al2O3 thin films

DeCoster, Mallory E.; Meyer, Kelsey; Piercy, Brandon D.; Gaskins, John T.; Donovan, Brian F.; Giri, Ashutosh; Strnad, Nicholas A.; Potrepka, Daniel M.; Wilson, Adam A.; Losego, Mark D.; Hopkins, Patrick E.

doi:10.1016/j.tsf.2018.01.058

Cited by 39 publications

(24 citation statements)

References 50 publications

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“…We note that this model is valid in the regime where diffusive thermal transport is predominant. We also set the upper and lower bounds for κ eff based on the values found in prior studies for thermal ALD. , Here, we consistently apply the thermal boundary resistance to be 10 m 2 K GW –1 , which is generally considered to be within a typical range. , We find that the measured effective thermal conductivity for bias voltage smaller than ∼41 V falls within the estimated bounds, as seen in Figure a. However, the effective thermal conductivity deviates below the estimated lower bound at higher voltages (e.g., bias voltage >∼97 V), which is consistent with the increase in GPC, resulting in potential degradation of the film quality, as discussed above.…”

Section: Discussionsupporting

confidence: 78%

“…These values are within the typical range found in prior reports for amorphous Al 2 O 3 thin films deposited using thermal ALD at an operating temperature between 50 and 300 °C (region bounded by gray dashed lines in Figure ). ,,− Here, we estimate the effective thermal conductivity from references by assuming neighboring thermal interfacial resistance contribution of 10 m 2 K GW –1 . , We note that this approach is applied throughout the paper for our experimental results.…”

Section: Resultsmentioning

confidence: 99%

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Tunable Dielectric and Thermal Properties of Oxide Dielectrics via Substrate Biasing in Plasma-Enhanced Atomic Layer Deposition

Kim

Kwon

Han

et al. 2020

ACS Appl. Mater. Interfaces

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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 plasmaenhanced 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 Al 2 O 3 . 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.

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Section: Discussionsupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Tunable Dielectric and Thermal Properties of Oxide Dielectrics via Substrate Biasing in Plasma-Enhanced Atomic Layer Deposition

Kim

Kwon

Han

et al. 2020

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

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“…Thermal resistances of Ni and Au layers are neglected due to high thermal conductance and so is the interfacial resistance between them. The amorphous aluminum oxide thin films within 60 nm show similar thermal conductivity, reported by DeCoster et al 23 Thus, the thermal resistance of aluminum oxide films is the same across all samples. The thermal resistance above the silicon substrate for each sample is…”

Section: Interfacial Thermal Resistance Characterizationsupporting

confidence: 82%

Reducing interfacial thermal resistance between metal and dielectric materials by a metal interlayer

Park

Wang

et al. 2019

Journal of Applied Physics

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Interfacial thermal resistance between metal and dielectric materials is a bottleneck of the thermal management for modern integrated circuits as interface density increases with thinner films. In this work, we have observed that the interfacial resistance across gold and aluminum oxide can be reduced from 4.8Â10 À8 m 2 K=W to 1.4Â10 À8 m 2 K=W after adding a nickel layer in between, which represents a 70% reduction. The two temperature model is applied to explain the reduction of interfacial resistance, and the results show that the nickel layer functions as a bridge that reduces the phonon mismatch between gold and aluminum oxide. Moreover, nickel has strong electron-phonon coupling, which reduces the thermal resistance caused by the weak electron-phonon coupling in gold.

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“…Recently, there are several studies of considering anharmonicity in AGF [270,279], but there are still some limitations like high computational costs and inaccuracy from estimated scattering rate at interfaces. At interfaces between two crystalline materials, because of the growth limitation, the crystalline quality of one or both of the materials near the interface is usually not very good or the interfacial bonding is not very strong from different growing methods, like evaporation [262], CVD [115,280], and atomic layer deposition [281,284]. The low-quality polycrystalline or even amorphous region near the interface will have reduced thermal conductivity compared to bulk crystal and will contribute an additional thermal resistance, and that thermal resistance might impede the thermal transport from devices, especially for high frequency applications.…”

Section: Enhancement Of Thermal Transport Across Power Electronics Interfaces (Shi and Graham)mentioning

confidence: 99%

Applications and Impacts of Nanoscale Thermal Transport in Electronics Packaging

Warzoha

Wilson

Donovan

et al. 2021

Journal of Electronic Packaging

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This review introduces relevant nanoscale thermal transport processes that impact thermal abatement in power electronics applications. Specifically, we highlight the importance of nanoscale thermal transport mechanisms at each layer in material hierarchies that make up modern electronic devices. This includes those mechanisms that impact thermal transport through: (1) substrates, (2) interfaces and 2-D materials and (3) heat spreading materials. For each material layer, we provide examples of recent works that (1) demonstrate improvements in thermal performance and/or (2) improve our understanding of the relevance of nanoscale thermal transport across material junctions. We end our discussion by highlighting several additional applications that have benefited from a consideration of nanoscale thermal transport phenomena, including RF electronics and neuromorphic computing.

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Density and size effects on the thermal conductivity of atomic layer deposited TiO2 and Al2O3 thin films

Cited by 39 publications

References 50 publications

Tunable Dielectric and Thermal Properties of Oxide Dielectrics via Substrate Biasing in Plasma-Enhanced Atomic Layer Deposition

Tunable Dielectric and Thermal Properties of Oxide Dielectrics via Substrate Biasing in Plasma-Enhanced Atomic Layer Deposition

Reducing interfacial thermal resistance between metal and dielectric materials by a metal interlayer

Applications and Impacts of Nanoscale Thermal Transport in Electronics Packaging

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