Sol-Gel Derived Silica Layers for Low-k Dielectrics Applications

2000 ◽  
Vol 612 ◽  
Author(s):  
Sylvie Acosta ◽  
André Ayral ◽  
Christian Guizard ◽  
Charles Lecornec ◽  
Gérard Passemard ◽  
...  
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Thin Layers ◽  
Gaseous Ammonia ◽  
Potential Candidate ◽  
Average Pore ◽  
Synthesis Strategy ◽  
Silica Layers ◽  
Highly Porous

AbstractPorous silica exhibits attractive dielectric properties, which make it a potential candidate for use as insulator into interconnect structures. A new way of preparation of highly porous silica layers by the sol-gel route was investigated and is presented. The synthesis strategy was based on the use of common and low toxicity reagents and on the development of a simple process without gaseous ammonia post-treatment or supercritical drying step. Defect free layers were deposited by spin coating on 200 mm silicon wafers and characterized. Thin layers with a total porosity larger than 70% and an average pore size of 5 nm were produced. The dielectric constant measured under nitrogen flow on these highly porous layers is equal to ∼ 2.5, which can be compared to the value calculated from the measured porosity, ∼ 1.9. This difference is explained by the presence of water adsorbed on the hydrophilic surface of the unmodified silica.

Sol-Gel Processing of Low Dielectric Constant Nanoporous Silica Thin Films

2001 ◽  
Vol 703 ◽  
Author(s):  
Deok-Yang Kim ◽  
Henry Du ◽  
Suhas Bhandarkar ◽  
David W. Johnson
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Dielectric Constants ◽  
Gelling Agent ◽  
Porous Films ◽  
Average Pore

ABSTRACTTetramethyl ammonium silicate (TMAS) is known as a structuring agent in zeolite synthesis. We report its first use to prepare porous silica films for low k dielectric applications in microelectronics. A solution of TMAS 18.7 wt. % was spin coated on silicon substrates with a 3000 Å thick thermal oxide. The spin coated films were subsequently heat-treated at 450°C to obtain porous silica. The use of TMAS solution without gelation led to films of only moderate porosity value of 10%. The addition of methyl lactate, a gelling agent, significantly increased film porosity and improved the pore size distribution. For example, 50% porosity and uniform pore size distribution (average pore size ∼ 40 Å) has been achieved. Dielectric constants (k) of our porous films are as low as 2.5.

Silica Sol-Gel Supported Nickel Nano-Catalyst for Hydrogen Production Using Microreactors

2005 ◽  
Vol 885 ◽  
Author(s):  
Krithi Shetty ◽  
Shihuai Zhao ◽  
Wei Cao ◽  
Naidu V. Seetala ◽  
Debasish Kuila
Keyword(s):  
Steam Reforming ◽  
Average Pore Size ◽  
Sol Gel ◽  
Supported Catalyst ◽  
Silica Sol ◽  
Average Pore ◽  
Steam Reforming Of Methanol ◽  
Nano Catalyst ◽  
Before And After ◽  
Reforming Reactions

ABSTRACTThe goal of this research is to investigate the activities of a non-noble nano-catalyst (Ni/SiO2) using Si-microreactors for steam reforming of methanol to produce hydrogen for fuel cells. The supported catalyst was synthesized by sol-gel method using Ni (II) salts and Si(C2H5O)4 as starting materials. EDX results indicate that the actual loading of Ni (5-6%) is lower than the intended loading of 12 %. The specific surface area of the silica sol-gel encapsulated Ni nano-catalyst is 452 m2/g with an average pore size of ∼ 3 nm. Steam reforming reactions have been carried out in a microreactor with 50 µm channels in the temperature range of 180-240 °C and atmospheric pressure. Results show 53% conversion of methanol with a selectivity of 74 % to hydrogen at 5 l/min and 200 °C. The magnetic properties of the catalysts were performed using a Vibrating Sample Magnetometer (VSM) to study the activity of the catalysts before and after the steam reforming reactions. The VSM results indicate much higher activity in the microreactor compared to macro-reactor and Ni forms non-ferromagnetic species faster in the microreactor.

scholarly journals Nanoporous Activated Carbon Derived from Rice Husk for High Performance Supercapacitor

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Huaxing Xu ◽  
Biao Gao ◽  
Hao Cao ◽  
Xueyang Chen ◽  
Ling Yu ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Capacitance ◽  
Current Density ◽  
Average Pore Size ◽  
Nanoporous Carbon ◽  
Cycle Life ◽  
Potential Candidate ◽  
Average Pore ◽  
Nanoporous Activated Carbon

Nanoporous activated carbon material was produced from the waste rice husks (RHs) by precarbonizing RHs and activating with KOH. The morphology, structure, and specific surface area were investigated. The nanoporous carbon has the average pore size of 2.2 nm and high specific area of 2523.4 m2 g−1. The specific capacitance of the nanoporous carbon is calculated to be 250 F g−1at the current density of 1 A g−1and remains 80% for 198 F g−1at the current density of 20 A g−1. The nanoporous carbon electrode exhibits long-term cycle life and could keep stable capacitance till 10,000 cycles. The consistently high specific capacitance, rate capacity, and long-term cycle life ability makes it a potential candidate as electrode material for supercapacitor.

Effects of Sintering Temperature on the Properties of Stainless Steel Foam

2015 ◽  
Vol 1087 ◽  
pp. 232-235
Author(s):  
Fazimah Mat Noor ◽  
N.I. Mad Rosip ◽  
Khairur Rijal Jamaludin ◽  
Sufizar Ahmad
Keyword(s):  
Stainless Steel ◽  
Average Pore Size ◽  
Vacuum Furnace ◽  
Stainless Steel 316L ◽  
Average Pore ◽  
X Ray ◽  
Replication Method ◽  
Pore Dimension ◽  
Steel Foam ◽  
Highly Porous

Foam replication method is capable of producing foams with a highly porous structure with adjustable pore dimension, shape and size. In this work, this method has been used to prepare stainless steel 316L foam and sintered at 1200°C, 1250°C and 1300°C in a vacuum furnace. The microstructure and elemental analysis of the sample were examined using scanning electron microscope (SEM) and Energy Dispersive X–Ray (EDX), while the mechanical properties of the samples was determined by using compression test. It was found that the average pore size was in the range of 330µm-350µm. The yield strength and elastic modulus are in the range of 58-66 GPa and 0.46-0.50GPa respectively.

Synthesis, characterization, and photocatalytic activity of silver and zinc co-doped TiO2 nanoparticle for photodegradation of methyl orange dye in aqueous solution

2019 ◽  
Vol 97 (9) ◽  
pp. 642-650 ◽  
Author(s):  
Gabriel O. Oladipo ◽  
Akinola K. Akinlabi ◽  
Samson O. Alayande ◽  
Titus A.M. Msagati ◽  
Hlengilizwe H. Nyoni ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Pore Size ◽  
Average Pore Size ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Rutile Phase ◽  
Absorption Bands ◽  
Average Pore ◽  
Methyl Orange Dye ◽  
Co Doped

In this study, TiO2 nanocrystals, 1 mol% Ag-doped TiO2, and 1 mol% Ag and 0.6 mol% Zn co-doped TiO2 powders were synthesized by the sol–gel route. Their photocatalytic activities on methyl orange dye under visible irradiation were investigated. The powders were characterized by X-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Brunauer–Emmett–Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The XRD results revealed the presence of a rutile phase with an average crystallite size of 9 and 11 nm. The UV–vis spectra showed a red-shift towards a longer wavelength with the corresponding decrease in band gap from 2.9 to 2.5 eV. The BET surface areas of the nanoparticles ranged from 4.7 to 11.8 m2 g−1 with an average pore size between 18.9 and 56.6 nm. The Ag-doped TiO2 has the largest surface area of 11.8 m2 g−1, whereas the Ag–Zn co-doped TiO2 was found to have the highest pore size and volume. The absorption bands at 750–500 cm−1 were attributed to the –O–Ti–O– bond in the TiO2 lattice. The photocatalytic efficiency was highest at an optimum pH of 4.1 for Ag–Zn co-doped TiO2. The results confirmed that Ag-doped and Ag–Zn co-doped TiO2 were more effective than pure TiO2. The kinetic data were fitted into a pseudo first-order equation using a Langmuir–Hinshelwood kinetic model.

scholarly journals Fabrication and Characterization of Strontium-Substituted Hydroxyapatite-CaO-CaCO3 Nanofibers with a Mesoporous Structure as Drug Delivery Carriers

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 179 ◽  
Author(s):  
Shiao-Wen Tsai ◽  
Wen-Xin Yu ◽  
Pai-An Hwang ◽  
Sheng-Siang Huang ◽  
Hsiu-Mei Lin ◽  
...  
Keyword(s):  
Drug Carrier ◽  
Drug Loading ◽  
Average Pore Size ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Drug Carriers ◽  
Burst Release ◽  
Doping Amount ◽  
Sem Images ◽  
Average Pore

Hydroxyapatite (HAp) is the main inorganic component and an essential part of hard bone and teeth. Due to its excellent biocompatibility, bioactivity, and osteoconductivity, synthetic HAp has been widely used as a bone substitute, cell carrier, and therapeutic gene or drug carrier. Recently, numerous studies have demonstrated that strontium-substituted hydroxyapatite (SrHAp) not only enhances osteogenesis but also inhibits adipogenesis in mesenchymal stem cells. Mesoporous SrHAp has been successfully synthesized via a traditional template-based process and has been found to possess better drug loading and release efficiencies than SrHAp. In this study, strontium-substituted hydroxyapatite-CaO-CaCO3 nanofibers with a mesoporous structure (mSrHANFs) were fabricated using a sol–gel method followed by electrospinning. X-ray diffraction analysis revealed that the contents of CaO and CaCO3 in the mSrHANFs decreased as the doping amount of Sr increased. Scanning electron microscopy (SEM) images showed that the average diameter of the mSrHANFs was approximately 200~300 nm. The N2 adsorption–desorption isotherms demonstrated that the mSrHANFs possessed a mesoporous structure and that the average pore size was approximately 20~25 nm. Moreover, the mSrHANFs had excellent drug- loading efficiency and could retard the burst release of tetracycline (TC) to maintain antibacterial activity for over 3 weeks. Hence, mSrHANFs have the potential to be used as drug carriers in bone tissue engineering.

Highly Porous Silica Nanoaerogels for Ultrafast Nonlinear Optical Applications

2005 ◽  
Vol 287 ◽  
pp. 352-357 ◽  
Author(s):  
Jae Tae Seo ◽  
S.M. Ma ◽  
K. Lee ◽  
H. Brown ◽  
A. Jackson ◽  
...  
Keyword(s):  
Apparent Density ◽  
Homeland Security ◽  
Sol Gel ◽  
Nonlinear Refraction ◽  
Porous Silica ◽  
Signal Beam ◽  
Supercritical Fluid Drying ◽  
Optical Applications ◽  
Nonlinear Optical Applications ◽  
Highly Porous

Highly porous silica nanoaerogels with low apparent density of ~0.1 g/cm3 and ~0.07 g/cm3 were synthesized through two-step sol-gel processing and low temperature supercritical fluid drying. The nonlinear refraction (γ) of silica nanoaerogels was estimated to be ~ -3.4 x 10-16 m2/W for ~0.1 g/cm3 and ~0.07 g/cm3 apparent densities with a signal-beam femtosecond z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica nanoaerogels was almost four orders larger than that of bulk silica materials. The large nonlinearrefraction with high nonlinear figure of merit (γ/βλ, β~2×10-10 m/W for 0.07 g/cm3 apparent density, β~6×10-10 m/W for 0.1 g/cm3 apparent density, λ~0.775 µm) is an ideal optical property for nonlinear applications of homeland security, battlefield enhancement, and industrial uses.

Determination of Local Mechanical Properties of Si3N4 Based Foams

2014 ◽  
Vol 606 ◽  
pp. 213-216 ◽  
Author(s):  
Zuzana Vilčeková ◽  
Monika Kašiarová ◽  
Magdaléna Domanická ◽  
Miroslav Hnatko ◽  
Pavol Šajgalík
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Resonant Frequency ◽  
Volume Fraction ◽  
Average Pore Size ◽  
Polyurethane Foams ◽  
Average Pore ◽  
Replication Method ◽  
Highly Porous

Local mechanical properties, particularly the hardness and Youngs modulus of highly porous silicon nitride based foams were studied in this work. Silicon nitride foams were prepared using polyurethane foam replication method to obtain appropriate cellular structure suitable for bio-application. Two types of the polyurethane foams were used (with average pore size 0.48 mm and 0.62 mm). Some of these samples were prepared by single or multiple infiltrations. The effects of structures, temperature of calcination, volume fraction of Si3N4 powder and number of the infiltrations on the local mechanical properties were investigated. The Youngs modulus of studied samples range from 12 to 46 GPa at the macroscopic scale measured by resonant frequency technique and from 10 to 28 GPa at the microscopic scale measured by instrumented indentation. Results showed increase of the hardness and Youngs modulus with increasing of the calcination temperature, with increasing of the number of infiltrations and also with increasing of volume fraction of Si3N4 powder in suspension. The results obtained from nanoindentation carry out lower values in comparison with the values measured by resonant frequency technique.

Porous TiO2-Al2O3 Photocatalyst: The Effects of Calcination Time

2012 ◽  
Vol 496 ◽  
pp. 165-168 ◽  
Author(s):  
Wen Jie Zhang ◽  
Hong Liang Xin
Keyword(s):  
Composite Materials ◽  
Average Pore Size ◽  
Sol Gel ◽  
Specific Area ◽  
Maximum Activity ◽  
Calcination Time ◽  
Average Pore ◽  
Porous Tio2 ◽  
Al2o3 Composite ◽  
Ft Ir

Porous TiO2-Al2O3 composite materials were prepared through sol-gel method after calcination at 500 oC for different time. FT-IR spectra of porous TiO2-Al2O3 composite materials revealed that the samples are composed of Al2O3 and TiO2. The sample calcinated for 2.5 h had the maximum specific area of 128.9 m2•g-1. High pore volume and average pore size were possessed by the samples calcinated for 1 h and 3 h. While being calcinated at 500 oC, photocatalytic activities of the materials increased at first and then dropped down with the increasing calcination time. The sample calcinated for 3 h showed the maximum activity of 35%.

Preparation and Characterization of Porous Silica Obtained by Hydrochloric Acid Selective Leaching Metakaolinite

2008 ◽  
Vol 368-372 ◽  
pp. 342-344
Author(s):  
Lin Jiang Wang ◽  
Xiang Li Xie
Keyword(s):  
Hydrochloric Acid ◽  
Layered Structure ◽  
Layer Structure ◽  
Average Pore Size ◽  
Porous Silica ◽  
Total Pore Volume ◽  
Selective Leaching ◽  
Average Pore ◽  
Hcl Solution

Porous silica was prepared by selective leaching of metakaolinite with 20 mass% HCl solution. The metakaolinite was derived from the 1:1 layered structure clay mineral kaolinite by firing at 600°C for 24 h. The characteristics of porous silica were studied. The content of Al2O3 in metakaolinite was sharply changed from 45% to less than 2% after 2 h leaching. The maximum specific surface area of the leached sample was about 350 m2/g. The average pore size is about 2 nm. The total pore volume is 0.3 ml/g. The layer structure of kaolinite and metakaolinite is responsible for forming micropores.

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