Thermal conductivity and thermal boundary resistance of atomic layer deposited high-k dielectric aluminum oxide, hafnium oxide, and titanium oxide thin films on silicon

Ethan A Scott,Patrick E Hopkins,Sean W King,John T Gaskins

doi:10.1063/1.5021044

Ethan A Scott, Patrick E Hopkins + Show 2 more

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https://doi.org/10.1063/1.5021044

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Journal: APL materials	Publication Date: May 1, 2018
Citations: 83	License type: cc-by

Affiliation: University of Virginia, Intel (United States)

Abstract

The need for increased control of layer thickness and uniformity as device dimensions shrink has spurred increased use of atomic layer deposition (ALD) for thin film growth. The ability to deposit high dielectric constant (high-k) films via ALD has allowed for their widespread use in a swath of optical, optoelectronic, and electronic devices, including integration into CMOS compatible platforms. As the thickness of these dielectric layers is reduced, the interfacial thermal resistance can dictate the overall thermal resistance of the material stack compared to the resistance due to the finite dielectric layer thickness. Time domain thermoreflectance is used to interrogate both the thermal conductivity and the thermal boundary resistance of aluminum oxide, hafnium oxide, and titanium oxide films on silicon. We calculate a representative design map of effective thermal resistances, including those of the dielectric layers and boundary resistances, as a function of dielectric layer thickness, which will be of great importance in predicting the thermal resistances of current and future devices.

Highlights

These thermal resistances are of critical importance in consideration of current and future CMOS device performance and reliability
While the overwhelming majority of studies have focused on the electronic properties of ALD high-k dielectrics, few studies have reported on thermal conductivity measurements on ALD Al2O3,8–11 HfO2,8,9,12 and TiO2 films.[13,14]
The variability of thermal boundary resistances (TBRs) with extrinsic parameters such as surface roughness,[7,15,16,17] interfacial bonding environment,[18,19,20,21,22,23,24,25,26] and other defects at or near the interface[27,28,29,30,31,32,33] makes the measurement of the thermal conductivity, κ, of ALD-grown thin films and their respective TBRs most critical on samples fabricated under conditions consistent with current and future CMOS devices

Summary

Introduction

The thermal conductivity and thermal boundary resistance between device layers play a role in the overall thermal resistance of devices, especially as device layers in a variety of applications are routinely on the order of sub-100 nm.[1,2] These thermal resistances are of critical importance in consideration of current and future CMOS device performance and reliability. We report the thermal conductivity, TBR, and total thermal resistance for ALDgrown Al2O3, HfO2, and TiO2 thin films on silicon substrates via time domain thermoreflectance (TDTR).

Results

Conclusion