Processing dependent thermal conductivity of nanoporous silica xerogel films

2002 ◽  
Vol 91 (5) ◽  
pp. 3275-3281 ◽  
Author(s):  
Anurag Jain ◽  
Svetlana Rogojevic ◽  
Shom Ponoth ◽  
William N. Gill ◽  
Joel L. Plawsky ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silica Xerogel ◽  
Nanoporous Silica ◽  
Xerogel Films

Fabrication and Characterization of Spin-On Silica Xerogel Films

1998 ◽  
Vol 511 ◽  
Author(s):  
S. Nitta ◽  
A. Jain ◽  
V. Pisupatti ◽  
W. N. Gill ◽  
P. C. Wayner ◽  
...  
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Convective Diffusion ◽  
Ambient Pressure ◽  
Silica Xerogel ◽  
High Porosity ◽  
Thermal Oxide ◽  
Fabrication And Characterization ◽  
Xerogel Films

ABSTRACTXerogel films of high porosity were fabricated using an ambient pressure technique. The same porosity can be obtained with different microstructures by varying the aging time of the films. The dielectric constant of these films as a function of porosity at 1 MHz follows correlations originally developed for bulk aerogels. Diffusion of copper is orders of magnitude faster in these xerogels than in the corresponding thermal oxide. An activation energy of 0.9 eV was estimated based on a convective diffusion model.

scholarly journals Effective thermal conductivity of divided silica xerogel beds

2004 ◽  
Vol 350 ◽  
pp. 379-384 ◽  
Author(s):  
A. Bisson ◽  
A. Rigacci ◽  
D. Lecomte ◽  
P. Achard
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Silica Xerogel

Processing and Characterization of Silica Xerogel Films for Low-K Dielectric Applications

1999 ◽  
Vol 565 ◽  
Author(s):  
Anurag Jain ◽  
Svetlana Rogojevic ◽  
Satya V. Nitta ◽  
Venumadhav Pisupatti ◽  
William N. Gill ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Concrete Surface ◽  
Dielectric Constants ◽  
Silica Xerogel ◽  
High Porosity ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Lift Off ◽  
Surface Modified ◽  
Xerogel Films

AbstractSurface modified silica xerogel films of high porosity (60 - 90 %) and uniform thickness (0.4–2 μm) were fabricated at ambient pressure on silicon and silicon dioxide. The rheological properties that govern film uniformity were determined. A relation between the final dried film thickness and spin speed was developed. The porosity and thickness of the films could be controlled independently. The same porosity could be obtained over a wide range of aging time and temperature combinations. Fracture toughness was measured using the edge-lift-off technique. The best values were comparable to concrete. Surface modification was affected by treating the film with trimethylcholorosilane (TMCS) and other modifiers. Moisture adsorption was studied at 100% RH using a quartz crystal microbalance technique. Depending upon the degree and kind of surface treatment, films absorbed as much as 32% or as little as 2% of their weight in water. Dielectric constants (K), losses and breakdown strengths were comparable to values for calcined, bulk aerogels. Thin (≤ 500 Å) films of Copper (Cu) and Tantalum (Ta) were deposited on xerogel films and subjected to thermal annealing. No diffusion was observed within the limits of RBS. High-density plasma etching showed that the films etch an order of magnitude faster than conventional SiO2 films.

Effect of Sub-Continuum Energy Transport on Effective Thermal Conductivity in Nanoporous Silica (Aerogel)

2003 ◽  
Author(s):  
Brian R. Smith ◽  
Cristina H. Amon
Keyword(s):  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Energy Transport ◽  
Phonon Scattering ◽  
Amorphous Structure ◽  
Phonon Transport ◽  
Silica Matrix ◽  
Thin Layers ◽  
Nanoporous Silica ◽  
Macro Scale

This paper analyzes the effect of Fourier vs. subcontinuum heat transport through thin layers of nanoporous silica (aerogel) in the framework of an infrared focal plane array (IRFPA) sensor system. Aerogel is introduced as a compatible material for emerging microsystems applications and the comparison between aerogel and conventional insulation systems is analyzed. Correlations between aerogel’s macro-scale thermal properties and its nano-scale structure are discussed to address the effect of the material’s amorphous structure and sub-continuum phonon transport phenomena on macro-scale thermal conductivity. Simulations using the Lattice Boltzmann Method (LBM) quantify the effect of phonon scattering on silica conductivity. Techniques for extending the analysis to a three-dimensional silica matrix are discussed in light of recent advances in the simulation of aerogel morphology.

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