Thin Film Thermal Conductivity by Anharmonic Lattice Dynamics Calculations

2008 ◽  
Author(s):  
J. E. Turney ◽  
A. J. H. McGaughey ◽  
C. H. Amon
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Lattice Dynamics ◽  
Phonon Mode ◽  
Mode Shapes ◽  
Bulk Crystals ◽  
Anharmonic Lattice ◽  
Dynamics Simulations ◽  
Group Velocities

Lattice dynamics calculations are used to investigate thermal transport in argon thin films with thicknesses ranging between one and ten nanometers. Quasi-harmonic lattice dynamics calculations are used to find the frequencies and mode shapes of non-interacting phonons. This information is then used as input for anharmonic lattice dynamics calculations, whereby we compute the frequency shift and lifetime of each phonon mode due to interactions with other phonons. The phonon frequencies, group velocities, and lifetimes determined with the lattice dynamics techniques are then used to compute the in-plane thermal conductivity of the thin films as a function of film thickness. The thermal conductivities predicted by the lattice dynamics methods are compared to predictions from molecular dynamics simulations. Differences in the phonon characteristics in thin films compared to bulk crystals are examined by comparing the contribution to the thermal conductivity as a function of frequency.

Argon Thermal Conductivity by Anharmonic Lattice Dynamics Calculations

2008 ◽  
Author(s):  
J. E. Turney ◽  
A. J. H. McGaughey ◽  
C. H. Amon
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Lattice Dynamics ◽  
Mode Shapes ◽  
Face Centered Cubic ◽  
Phonon Modes ◽  
Anharmonic Lattice ◽  
The Face ◽  
Face Centered ◽  
Dynamics Simulations

Lattice dynamics calculations are used to investigate thermal transport in the face-centered cubic Lennard-Jones (LJ) argon crystal between temperatures of 20 and 80 K. First, quasi-harmonic lattice dynamics calculations are used to find the frequencies and mode shapes of non-interacting phonons [1]. This information is then used as input for anharmonic lattice dynamics calculations. Anharmonic lattice dynamics is a means of computing the frequency shift and lifetime of each phonon mode due to interactions with other phonons [2]. The phonon frequencies, group velocities, and lifetimes, determined with the lattice dynamics methods, are then used to compute the thermal conductivity. The thermal conductivities predicted by the lattice dynamics methods are compared to predictions from molecular dynamics simulations. The two methods are found to agree well at low temperature but diverge at higher temperatures (i.e., near the melting point). The properties of individual phonon modes are used to identify the modes that dominate thermal transport.

Silicon Thin-Film Lattice Dynamics and Thermal Transport Properties

2012 ◽  
Author(s):  
Bruce L. Davis ◽  
Mehmet Su ◽  
Ihab El-Kady ◽  
Mahmoud I. Hussein
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Transport Properties ◽  
Lattice Dynamics ◽  
Dielectric Materials ◽  
Phonon Transport ◽  
Solid State Physics ◽  
Silicon Thin Film ◽  
Silicon Thin Films

Thin films composed of dielectric materials are attracting growing interest in the solid state physics and nanoscale heat transfer communities. This is primarily due to their unique thermal and electronic properties and their extensive use as components in optoelectronic, and potentially in thermoelectric, devices. In this paper, an elaborate study is presented on silicon thin films ranging from a few nanometers in thickness to very thick bulk-like thicknesses. Full lattice dynamics calculations are performed incorporating the entire film cross section and the relaxation of the free surfaces. The phonon properties emerging from these calculations are then incorporated into Holland-Callaway models to predict the thermal conductivity and other phonon transport properties. A rigorous curve fitting process to a limited set of available experimental data is carried out to obtain the scattering lifetimes. Our results demonstrate the importance of proper consideration of the full thin-film dispersion description and provide insights into the relationship between thermal conductivity, film thickness and temperature.

Determination of Thermal Conductivity of Amorphous Silicon Thin Films via Non-Contacting Optical Probing

2006 ◽  
Vol 326-328 ◽  
pp. 689-692
Author(s):  
Seung Jae Moon
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Amorphous Silicon ◽  
Optical Transmission ◽  
Film Deposition ◽  
Transmission Measurement ◽  
Conductive Heat ◽  
Optical Transmission Measurement

The thermal conductivity of amorphous silicon (a-Si) thin films is determined by using the non-intrusive, in-situ optical transmission measurement. The thermal conductivity of a-Si is a key parameter in understanding the mechanism of the recrystallization of polysilicon (p-Si) during the laser annealing process to fabricate the thin film transistors with uniform characteristics which are used as switches in the active matrix liquid crystal displays. Since it is well known that the physical properties are dependent on the process parameters of the thin film deposition process, the thermal conductivity should be measured. The temperature dependence of the film complex refractive index is determined by spectroscopic ellipsometry. A nanosecond KrF excimer laser at the wavelength of 248 nm is used to raise the temperature of the thin films without melting of the thin film. In-situ transmission signal is obtained during the heating process. The acquired transmission signal is fitted with predictions obtained by coupling conductive heat transfer with multi-layer thin film optics in the optical transmission measurement.

The Elastic Moduli of Silver Thin Films Measured with a New Microtensile Tester

1991 ◽  
Vol 239 ◽  
Author(s):  
J. Ruud ◽  
D. Josell ◽  
A. L. Greer ◽  
F. Spaepen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Diffraction Grating ◽  
Strain Measurement ◽  
Elastic Moduli ◽  
Two Dimensional ◽  
Bulk Crystals ◽  
Free Standing ◽  
Tensile Direction ◽  
Silver Thin Films

ABSTRACTA new design for a thin film microtensile tester is presented. The strain is measured directly on the free-standing thin film from the displacement of laser spots diffracted from a thin grating applied to its surface by photolithography. The diffraction grating is two-dimensional, allowing strain measurement both along and transverse to the tensile direction. In principle, both Young's modulus and Poisson's ratio of a thin film can be determined. Ag thin films with strong <111> texture were tested. The measured Young moduli agreed with those measured on bulk crystals, but the measured Poisson ratios were low, most likely due to slight transverse folding of the film that developed during the test.

Improvement of Thermal Conductivity of Electroplated Copper Thin-Film Interconnections by Controlling Their Micro Texture

2014 ◽  
Author(s):  
Pornvitoo Rittinon ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Grain Boundaries ◽  
Diffraction Method ◽  
Electron Back Scatter Diffraction ◽  
High Resistivity ◽  
Copper Thin Film ◽  
Electroplated Copper ◽  
The Relationship

Copper thin films are indispensable for the interconnections in the advanced electronic products, such as TSV (Trough Silicon Via), fine bumps, and thin-film interconnections in various devices and interposers. However, it has been reported that both electrical and mechanical properties of the films vary drastically comparing with those of conventional bulk copper. The main reason for the variation can be attributed to the fluctuation of the crystallinity of grain boundaries in the films. Porous or sparse grain boundaries show very high resistivity and brittle fracture characteristic in the films. Thus, the thermal conductivity of the electroplated copper thin films should be varied drastically depending on their micro texture based on the Wiedemann-Franz’s law. Since the copper interconnections are used not only for the electrical conduction but also for the thermal conduction, it is very important to quantitatively evaluate the crystallinity of the polycrystalline thin-film materials and clarify the relationship between the crystallinity and thermal properties of the films. The crystallinity of the interconnections were quantitatively evaluated using an electron back-scatter diffraction method. It was found that the porous grain boundaries which contain a significant amount of vacancies increase the local electrical resistance in the interconnections, and thus, cause the local high Joule heating. Such porous grain boundaries can be eliminated by control the crystallinity of the seed layer material on which the electroplated copper thin film is electroplated.

Temperature Dependence of Thermal Conductivity of Amorphous and Crystal Thin Film by Molecular Dynamics Simulation

2007 ◽  
Author(s):  
Zhengxing Huang ◽  
Zhenan Tang ◽  
Suyuan Bai ◽  
Jun Yu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Integrated Circuits ◽  
Temperature Dependence ◽  
Amorphous Materials ◽  
Dynamics Simulation ◽  
Amorphous Sio2 ◽  
Film Boundary ◽  
Different Temperatures

For crystal materials, thermal conductivity (TC) is proportional to T3 at low temperatures and to T−1 at high temperatures. TCs of most amorphous materials decrease with the decreasing temperatures. If a material is thin film, boundary will influence the TC and then influence the temperature dependence. In this paper, we calculate the TC of crystal and amorphous SiO2 thin films, which is a commonly used material in micro devices and Integrated Circuits, by NEMD simulations. The calculation temperatures are from 100K to 700K and the thicknesses are from 2nm to 8nm. TCs of crystal thin films reach their peak values at different temperatures for different thicknesses. The smaller thickness the larger peak values obtained. But for amorphous thin films, the results show that the temperature dependence of thin films is the same as bulk materials and not relative to their thicknesses. The obtained temperature dependence of the thin films is consistent with some previous measurements and the theory predictions.

Measurement of the Thermal Conductivity and Heat Capacity of Freestanding Shape Memory Thin Films Using the 3ω Method

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Ankur Jain ◽  
Kenneth E. Goodson
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Shape Memory ◽  
Temperature Response ◽  
Thermal Response ◽  
Temperature Phase ◽  
Property Measurement ◽  
Low Temperature Phase

An accurate measurement of the thermophysical properties of freestanding thin films is essential for modeling and predicting thermal performance of microsystems. This paper presents a method for simultaneous measurement of in-plane thermal conductivity and heat capacity of freestanding thin films based on the thermal response to a sinusoidal electric current. An analytical model for the temperature response of a freestanding thin film to a sinusoidal heating current passing through a metal heater patterned on top of the thin film is derived. Freestanding thin-film samples of silicon nitride and nickel titanium (NiTi), a shape memory alloy, are microfabricated and characterized. The thermal conductivity of thin-film NiTi, which increases linearly between 243K and 313K, is 40% lower than the bulk value at room temperature. The heat capacity of NiTi also increases linearly with temperature in the low temperature phase and is nearly constant above 280K. The measurement technique developed in this work is expected to contribute to an accurate thermal property measurement of thin-film materials. Thermophysical measurements on NiTi presented in this work are expected to aid in an accurate thermal modeling of microdevices based on the shape memory effect.

Molecular Dynamics Simulation on the Out-of Plane Thermal Conductivity of Single-Crystal Carbon Thin Films

2009 ◽  
Vol 60-61 ◽  
pp. 430-434 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun ◽  
Guo Qiang Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Potential Energy ◽  
Film Thickness ◽  
Single Crystal ◽  
Diamond Crystal ◽  
Dynamics Simulation ◽  
Crystal Direction

In this article, we select corresponding Tersoff potential energy to build potential energy model and investigate the thermal conductivities of single-crystal carbon thin-film. The equilibrium molecular dynamics (EMD) method is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (001), and the non-equilibrium molecular dynamics (NEMD) is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (111). The results of calculations demonstrate that the nanometer thin film thermal conductivity of diamond crystal is remarkably lower than the corresponding bulk experimental data and increase with increasing the film thickness, and the nanometer thin film thermal conductivity of diamond crystal relates to film thickness linearly in the simulative range. The nanometer thin film thermal conductivity also demonstrates certain regularity with the change of temperature. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of nanometer thin films.

Sign in / Sign up

Export Citation Format

Share Document