On the influence of thin absorber layers in thermal-wave applications

1986 ◽  
Vol 64 (9) ◽  
pp. 1287-1290 ◽  
Author(s):  
R. Tilgner ◽  
J. Baumann ◽  
M. Beyfuss
Keyword(s):  
Thermal Diffusion ◽  
Thermal Wave ◽  
Thermal Response ◽  
Absorber Layer ◽  
Thermal Waves ◽  
Wave Approach ◽  
Quantitative Results ◽  
Complex Temperature

The influence on the thermal response of a sample under photothermal investigation is analyzed when real absorbing layers are used as a source of thermal waves. Experiments with glass and copper samples covered by various absorbing layers are described using a thermal-wave approach. It is demonstrated that matching the effusivities of absorber and substrate is essential for obtaining quantitative results even for absorber layers much thinner than their thermal-diffusion lengths; otherwise one has to determine very carefully the particular nonneglectable influence of the absorber layer on the measured complex temperature.

Thermal wave imaging of microelectronics

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Miguel Goni ◽  
Aaron J. Schmidt
Keyword(s):  
Thermal Properties ◽  
Surface Temperature ◽  
Thermal Wave ◽  
High Frequency ◽  
Low Frequency ◽  
Thermal Response ◽  
Glass Layer ◽  
Thermal Waves ◽  
Frequency Wave ◽  
Thermal Penetration Depth

Thermal waves can reveal thermal properties of different layers forming a multilayer structure. If the thickness of each layer is known, specific ranges of thermal wave frequencies can be implemented to study the thermal response of a specific number of layers and eventually extract the thermal properties of individual layers. As a first approach this idea can be simplified by means of the thermal penetration depth parameter, δ. The thermal penetration depth is defined as, δ=k/πCf, where k and C are respectively the thermal conductivity and volumetric heat capacity of the material carrying the thermal wave and f is the frequency of the thermal wave. From this expression it can be seen how it is possible to constrain the material thermal response to a desired depth by controlling the frequency. Thus, using high enough frequencies, the top layer properties would be measured first. Decreasing the thermal wave frequency by an appropriate amount would include the next layer in the thermal response. Since the properties of the first layer are now known, it would be possible to extract the properties of the current layer. The measurement would continue in a similar fashion for the remaining layers. Frequency domain thermoreflectance (FDTR) can be used to generate thermal waves. In this technique, a periodically modulated continuous wave laser (red pump beam) provides the periodic heat flux input into the material while a second laser (green probe beam) monitors the surface temperature through a proportional change of the surface reflectivity. The measured value is the phase lag (degrees) between the incoming thermal wave and the surface temperature response. In this study, an FDTR system was used in conjunction with a piezo stage to obtain thermal images of two different multilayer structures. The first one consisted of a CPU chip formed mainly by layers of SiO2 and Cu. The second case consisted of a TFT LCD screen from a mobile device. Regarding the CPU chip, the low frequency thermal wave travelled well past the second layer of Cu wires and provided thermal information about the bottom layers of the chip. In contrast, the high frequency wave could not penetrate through the second layer, which resulted in a more sensitive response upon the Cu wires close to the surface. A similar phenomenon occurred with the LCD screen. In this case the top layer was a glass layer used to sandwich the liquid crystal and the second layer is composed of the ITO electrodes that provide the electric field. It can be observed how the high frequency wave did not penetrate through the top glass layer providing no thermal information about the bottom layer as opposed to the low frequency wave, which clearly shows the ITO electrodes. The estimated thermal penetration depths displayed on top of each image were calculated using the equation provided before with known thermal properties of SiO2, Cu and ITO.

Nanofluids: Synthesis, Heat Conduction, and Extension

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Liqiu Wang ◽  
Xiaohao Wei
Keyword(s):  
Heat Conduction ◽  
Olive Oil ◽  
Thermal Wave ◽  
Thermal Waves ◽  
Water Conductivity ◽  
Conductivity Enhancement ◽  
Chemical Solution Method ◽  
New Type ◽  
Fourier Heat Conduction ◽  
Two Phases

We synthesize eight kinds of nanofluids with controllable microstructures by a chemical solution method (CSM) and develop a theory of macroscale heat conduction in nanofluids. By the CSM, we can easily vary and manipulate nanofluid microstructures through adjusting synthesis parameters. Our theory shows that heat conduction in nanofluids is of a dual-phase-lagging type instead of the postulated and commonly used Fourier heat conduction. Due to the coupled conduction of the two phases, thermal waves and possibly resonance may appear in nanofluid heat conduction. Such waves and resonance are responsible for the conductivity enhancement. Our theory also generalizes nanofluids into thermal-wave fluids in which heat conduction can support thermal waves. We emulsify olive oil into distilled water to form a new type of thermal-wave fluids that can support much stronger thermal waves and resonance than all reported nanofluids, and consequently extraordinary water conductivity enhancement (up to 153.3%) by adding some olive oil that has a much lower conductivity than water.

Imaging with optically generated thermal waves

1986 ◽  
Vol 320 (1554) ◽  
pp. 181-186 ◽  
Keyword(s):  
Thermal Wave ◽  
Optical Power ◽  
Thermal Waves ◽  
Thermal Structures ◽  
Non Destructive

By absorption of modulated optical power, a thermal wave is generated that interacts with thermal discontinuities. Imaging with scanned local thermal-wave probing is suited for non-contacting and non-destructive inspection of thermal structures in solids.

Ion Implantation Monitoring of GaAs Using Thermal Waves

1993 ◽  
Vol 316 ◽  
Author(s):  
R. Garcia ◽  
E. J. Jaquez ◽  
R.J. Culbertson ◽  
C. D'Acosta ◽  
C. Jasper
Keyword(s):  
Activation Energy ◽  
Thermal Properties ◽  
Ion Implantation ◽  
Diffusion Process ◽  
Thermal Wave ◽  
Room Temperature ◽  
Implantation Dose ◽  
Thermal Waves ◽  
Crystal Imperfections ◽  
Logarithmic Decay

ABSTRACTLaser modulated thermoreflectivity, also called thermal wave technology, has been used in recent years to monitor ion implantation dose by monitoring the damage due to implantation. The thermal properties which are affected by lattice perturbations and other crystal imperfections are tracked by this technique. A gauge capability study was performed on the Thermawave TP300 for monitoring ion implantation of GaAs wafers. The results are presented. In order to determine the sensitivity of the technique to changes in dose, a matrix of GaAs and Si wafers was measured. During this study a downward trend was observed in the repeatability of our results. It is shown that damage to a sample during implantation will relax to a certain degree at room temperature. This damage relaxation can take up to 80 hours at room temperature and can be observed using thermal waves. It is shown that “hot wafer decay” follows a logarithmic decay which is indicative of a diffusion process. At 180°C the decay lasts less than 1 minute which indicates that the defects causing this phenomenon have a low activation energy.

Thermal Transport in Hotspots Using the Lattice Boltzmann Method with Application to Silicon-on-Insulator Transistors

2014 ◽  
Vol 960-961 ◽  
pp. 337-340
Author(s):  
Yu Dong Mao ◽  
Ming Tian Xu
Keyword(s):  
Energy Density ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Thermal Wave ◽  
Electronic Devices ◽  
Silicon On Insulator ◽  
Thermal Waves ◽  
Fourier Law ◽  
Wave Effect ◽  
Boltzmann Method

Silicon-on-insulator (SOI) transistors have been widely used in the micro-electronic devices. The Lattice Boltzmann method (LBM) is employed to simulate the heat conductions of hotspots appeared in a SOI transistor. The results show that a thermal wave effect is appeared in micro-region, and it can not be found in Fourier prediction. Comparing the results obtained by the Fourier law and LBM, we find that the LBM solution shows approximately 22% higher energy density than the Fourier prediction. When two thermal waves form different hotspots meet together, a significant energy enhancement will be appeared.

Rie-Induced Damage to Single Crystal Silicon Monitored with Nondestructive Thermal Waves

1986 ◽  
Vol 68 ◽  
Author(s):  
Patrice Geraghty ◽  
W. Lee Smith
Keyword(s):  
Process Parameters ◽  
Plasma Etching ◽  
Thermal Wave ◽  
Silicon Surface ◽  
Single Crystal Silicon ◽  
Thermal Waves ◽  
Process Variables ◽  
Crystal Silicon ◽  
Laser Probe ◽  
Damage Level

AbstractA method is presented to nondestructively monitor damage in silicon caused by reactive-ion or plasma etching on actual product wafers or test wafers immediately following the etch step.Data is taken on product wafers by scanning the 1-micron laser probe spot across and along the bottom of RIE-etched trenches.The onset of silicon damage brings a marked increase to the thermal wave (TW) signal: as the RIE bias voltage was increased from -60 volts to -250 volts, the TW signal increased monotonically by 1230%.The effects of other RIE process parameters on the damage level were also measured.This study allowed the RIE process variables to be adjusted to minimize damage to the silicon surface.

scholarly journals Thermal Bragg Shields for Thermal Waves.

2021 ◽  
Author(s):  
Angela Camacho de la Rosa ◽  
David Becerril ◽  
Guadalupe Gómez-Farfán ◽  
Raul Esquivel-Sir
Keyword(s):  
Heat Conduction ◽  
Dispersion Relation ◽  
Wave Phenomenon ◽  
Response Times ◽  
Thermal Response ◽  
Thermal Waves ◽  
Thin Metallic Film ◽  
Very High ◽  
High Reflectance

Abstract Ultrafast heating processes do not follow Fourier's heat conduction law, but rather the proposed Cattaneo-Vernotte equation (CVe) which has wave-like solutions that have some important differences from other wave phenomenon. In a periodic system made of materials with different thermal conductivities, solutions of the CVe lead to a band-like structure in the dispersion relation. In this work, we show that highly reflective Bragg mirrors for thermal waves can be designed. Even for a mirrors with a few layers a very high reflectance is achieved (>90%). The mirrors are made of materials with large thermal response times, where thermal waves have been measured. A second alternative consists of adding a thin metallic film which also leads to an efficient thermal Bragg mirror. Finally, the role of defects in opening new thermal-stop bands is demonstrated.

Damping and Resonance Characteristics of Thermal Waves

1992 ◽  
Vol 59 (4) ◽  
pp. 862-867 ◽  
Author(s):  
Da Yu Tzou
Keyword(s):  
Resonance Frequency ◽  
Thermal Wave ◽  
High Frequency ◽  
Wave Speed ◽  
Thermal Waves ◽  
Resonance Behavior ◽  
Engineering Materials

Amplification of thermal waves in response to high-frequency excitations is studied in this work. The resonance behavior is explored along with the underdamped behavior in thermal wave oscillations. In transition from an overdamped to an underdamped wave behavior, the relaxation distance is found to dominate the process. A relationship between the resonance frequency and the thermal wave speed is derived. The emphasis is placed on the frequency approach determining the thermal wave speed in engineering materials.

Few-atomic-layer boron nitride nanosheets synthesized in solid thermal waves

RSC Advances ◽  
2015 ◽  
Vol 5 (12) ◽  
pp. 8579-8584 ◽  
Author(s):  
Hayk H. Nersisyan ◽  
Tae-Hyuk Lee ◽  
Kap-Ho Lee ◽  
Young-Soo An ◽  
Jin-Seok Lee ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Thermal Wave ◽  
Hexagonal Boron Nitride ◽  
Atomic Layer ◽  
Thermal Waves ◽  
Boron Nitride Nanosheets

Few-atomic-layer hexagonal boron nitride (h-BN) sheets were synthesized in a solid thermal wave implemented in a B2O3 + (3 + 0.5k)Mg + kNH4Cl mixture.

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