Micromachining of mesoporous oxide films for microelectromechanical system structures

2002 ◽  
Vol 17 (8) ◽  
pp. 2121-2129 ◽  
Author(s):  
Jong-Ah Paik ◽  
Shih-Kang Fan ◽  
Chang-Jin Kim ◽  
Ming C. Wu ◽  
Bruce Dunn
Keyword(s):  
Sacrificial Layer ◽  
Oxide Films ◽  
Average Diameter ◽  
High Porosity ◽  
Mems Devices ◽  
Mesoporous Films ◽  
Microelectromechanical System ◽  
Mesoporous Oxide ◽  
Structure Layer ◽  
Mesoporous Oxides

The high porosity and uniform pore size of mesoporous oxide films offer unique opportunities for microelectromechanical system (MEMS) devices that require low density and low thermal conductivity. This paper provides the first report in which mesoporous films were adapted for MEMS applications. Mesoporous SiO2 and Al2O3 films were prepared by spin coating using block copolymers as the structure-directing agents. The resulting films were over 50% porous with uniform pores of 8-nm average diameter and an extremely smooth surface. The photopatterning and etching characteristics of the mesoporous films were investigated and processing protocols were established which enabled the films to serve as the sacrificial layer or the structure layer in MEMS devices. The unique mesoporous morphology leads to novel behavior including extremely high etching rates and the ability to etch underlying layers. Surface micromachining methods were used to fabricate three basic MEMS structures, microbridges, cantilevers, and membranes, from the mesoporous oxides.

Preparation of Mesoporous Oxides for Mems Structures

2000 ◽  
Vol 657 ◽  
Author(s):  
Jong-Ah Paik ◽  
Nobuaki Kitazawa ◽  
Shih-Kang Fan ◽  
Chang-Jin Kim ◽  
Ming C. Wu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Roughness ◽  
Block Copolymers ◽  
Low Density ◽  
High Porosity ◽  
Mems Devices ◽  
Mems Fabrication ◽  
Mesoporous Oxide ◽  
Mesoporous Oxides ◽  
Uniform Pore Size

ABSTRACTThe high porosity and uniform pore size provided by mesoporous oxide films offer interesting opportunities for MEMS devices that require low density and low thermal conductivity. This paper describes recent efforts at adapting mesoporous films for MEMS fabrication. Mesoporous SiO2 and Al2O3 films were prepared using block copolymers as the structure-directing agents, leading to films which were 70% porous and < 5 nm surface roughness. A number of etchants were investigated and good etch selectivity was observed with both dry and wet systems. Micromachining methods were used to fabricate cantilevers, micro bridges and membranes.

scholarly journals Reducing the Hygroscopic Swelling in MEMS Sensor using Different Mold Materials

2020 ◽  
Vol 10 (1) ◽  
pp. 494
Author(s):  
Pinki Kumari ◽  
Kuldeep Singh ◽  
Anuj Singal
Keyword(s):  
Performance Analysis ◽  
Pressure Sensor ◽  
Ceramic Mold ◽  
Mems Devices ◽  
Challenging Problem ◽  
Microelectromechanical System ◽  
Saturation Concentration ◽  
Mems Sensor ◽  
Hygroscopic Swelling

Today, Hygroscopic swelling is one of the biggest challenging problem of Epoxy mold compound (EMC) in packaging with Microelectromechanical system (MEMS) devices. To overcome this hygroscopic swelling problem of EMC and guard the devices, MEMS devices are molded in this paper with different Mold Compound (MC) i.e. titanium and ceramic etc. during their interconnection with the board. Also, a comparatively performance analysis of this various mold compound with MEMS pressure sensor has been studied in this paper at 60% humidity, 140 mol/m<sup>3</sup> saturation concentration and 25 <sup>o</sup>C. It was observed that hygroscopic swelling does not take place in the titanium mold compound. But, titanium is very costly so we have to consider something cheaper material i.e. ceramic in this paper. The Hygroscopic swelling in Ceramic Mold Compound after 1 year is nearly 0.05mm which is very less than epoxy.

Feasibility of screen-printed PZT microceramics for Structural Health Monitoring piezocomposites applications

2013 ◽  
Vol 2013 (CICMT) ◽  
pp. 000020-000025
Author(s):  
Hélène DEBEDA ◽  
Riadh LAKHMI ◽  
Isabelle FAVRE ◽  
Jonathan ARGILLOS ◽  
Mario MAGLIONE ◽  
...  
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Sacrificial Layer ◽  
Low Cost ◽  
Thick Films ◽  
Impedance Analysis ◽  
High Porosity ◽  
Structural Health ◽  
Monitoring Applications ◽  
Screen Printing Technology

Using the association of the low-cost screen-printing technology with the sacrificial layer method, the feasibility of totally released piezoelectric thick-films microceramics of gold electroded PZT type is studied. After the deposition of the sacrificial layer on an alumina substrate and subsequent printing and drying of gold, PZT and gold layers, the final firing is performed at low temperature. This is followed by the releasing step of the Au/PZT/Au in diluted acidic solution. Impedance analysis shows that the electrical properties and electromechanical coefficients of poled PZT thick-films are still lower than those of PZT ceramics. This result is correlated to the high porosity rate of the PZT layer. However these piezoelectric microceramics present a good electromechanical behaviour and can be used as sensors when solicited by vibrations or as actuators to generate vibrations in a structure on which they are bonded. Moreover, the successful fabrication associated to a good electromechanical signature on a metallic test structure suggests Structural Health Monitoring applications.

scholarly journals Die-Attach Structure of Silicon-on-Glass MEMS Devices Considering Asymmetric Packaging Stress and Thermal Stress

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3979
Author(s):  
Jun Eon An ◽  
Usung Park ◽  
Dong Geon Jung ◽  
Chihyun Park ◽  
Seong Ho Kong
Keyword(s):  
Thermal Stress ◽  
Silicon Wafers ◽  
Experimental Results ◽  
Mems Devices ◽  
Microelectromechanical System ◽  
Die Attach ◽  
Lack Of Control ◽  
Die Bonding ◽  
Glass Process ◽  
Typical Process

Die attach is a typical process that induces thermal stress in the fabrication of microelectromechanical system (MEMS) devices. One solution to this problem is attaching a portion of the die to the package. In such partial die bonding, the lack of control over the spreading of the adhesive can cause non-uniform attachment. In this case, asymmetric packaging stress could be generated and transferred to the die. The performance of MEMS devices, which employ the differential outputs of the sensing elements, is directly affected by the asymmetric packaging stress. In this paper, we proposed a die-attach structure with a pillar to reduce the asymmetric packaging stress and the changes in packaging stress due to changes in the device temperature. To verify the proposed structure, we fabricated four types of differential resonant accelerometers (DRA) with the silicon-on-glass process. We confirmed experimentally that the pillar can control the spreading of the adhesive and that the asymmetric packaging stress is considerably reduced. The simulation and experimental results indicated that the DRAs manufactured using glass-on-silicon wafers as handle substrates instead of conventional glass wafers have a structure that compensates for the thermal stress.

Synthesis of organized mesoporous metal oxide films templated by amphiphilic PVA–PMMA comb copolymer

RSC Advances ◽  
2016 ◽  
Vol 6 (72) ◽  
pp. 67849-67857 ◽  
Author(s):  
Do Hyun Kim ◽  
Min Su Park ◽  
Hyung Hee Cho ◽  
Jung Tae Park ◽  
Jong Hak Kim
Keyword(s):  
Block Copolymers ◽  
Metal Oxide ◽  
Oxide Films ◽  
High Porosity ◽  
Metal Oxide Films ◽  
Comb Copolymer ◽  
Mesoporous Metal ◽  
Mesoporous Metal Oxide

We present a synthesis of organized mesoporous metal oxide films with high porosity and good interconnectivity using an amphiphilic PVA–PMMA comb copolymer which can be a promising template as an alternative to conventional block copolymers.

Preparation of mesoporous oxide films via block copolymer templating

2010 ◽  
Vol 356 (2) ◽  
pp. 109-113 ◽  
Author(s):  
Nobuaki Kitazawa ◽  
Yoshihisa Watanabe
Keyword(s):  
Block Copolymer ◽  
Oxide Films ◽  
Mesoporous Oxide

Platinum nanoparticle encapsulation during hydrothermal growth of mesoporous oxides: Synthesis, characterization and catalytic properties

2005 ◽  
Vol 900 ◽  
Author(s):  
Robert M. Rioux ◽  
Hyunjoon Song ◽  
James D Hoefelmeyer ◽  
Krisztian Niesz ◽  
Michael Grass ◽  
...  
Keyword(s):  
Particle Size ◽  
Platinum Nanoparticles ◽  
Heterogeneous Catalysts ◽  
Catalytic Properties ◽  
Synthetic Method ◽  
Ethylene Hydrogenation ◽  
Platinum Nanoparticle ◽  
Ordered Mesoporous ◽  
Mesoporous Oxide ◽  
Mesoporous Oxides

ABSTRACTA synthetic method for the design of heterogeneous catalysts incorporating monodisperse platinum nanoparticles into ordered mesoporous oxide frameworks has been developed. Nanoparticles were synthesized in solution in the presence of surface templating polymer and encapsulated into mesoporous oxide matrices. After polymer removal by calcination, ethylene hydrogenation rates were consistent with previously reported results, while superior activity of low coordination atoms in small crystallites during ethane hydrogenolysis was demonstrated. Changes in reaction selectivity with particle size during the hydrogenation/dehydrogenation of cyclohexene were attributed to a hydrogen coverage effect influencing the hydrogenation pathway and the apparent structure sensitivity of the dehydrogenation pathway.

Reducing the adhesion and friction forces of Si by coating ultra-thin Al2O3 films

RSC Advances ◽  
2014 ◽  
Vol 4 (92) ◽  
pp. 51047-51054 ◽  
Author(s):  
Zhimin Chai ◽  
Yuhong Liu ◽  
Xinchun Lu ◽  
Dannong He
Keyword(s):  
Tribological Performance ◽  
Mems Devices ◽  
Friction Forces ◽  
Microelectromechanical System ◽  
Al2o3 Films

Si-based microelectromechanical system (MEMS) devices cannot run reliably because of their poor tribological performance.

Fabrication and Characterization of Chitosan-Ethylenediaminetetraacetic Acid/Polyvinyl Alcohol Blend Electrospun Nanofibers

2011 ◽  
Vol 194-196 ◽  
pp. 648-651 ◽  
Author(s):  
Natthan Charernsriwilaiwat ◽  
Praneet Opanasopit ◽  
Theerasak Rojanarata ◽  
Tanasait Ngawhirunpat
Keyword(s):  
Polyvinyl Alcohol ◽  
Ethylenediaminetetraacetic Acid ◽  
Electrospun Fiber ◽  
High Surface ◽  
Weight Ratio ◽  
Average Diameter ◽  
High Porosity ◽  
Sem Images ◽  
Fiber Mats ◽  
Small Pore

Electrospinning is a technique use to fabricate ultrafine fibers with diameters in the nanometer range. The electrospun fiber mats have high potentials for many applications, due to their high surface area to volume, high porosity and small pore size. In this study, chitosan-ethylenediaminetetraacetic acid (CS-EDTA)/polyvinyl alcohol (PVA) blend nanofibers were successfully prepared using electrospinning techniques without organic solvent. CS was dissolved in EDTA aqueous solution and then blended with PVA solution at various weight ratios. Physicochemical properties of CS-EDTA/PVA solution such as viscosity, conductivity and surface tension were investigated. The morphology and diameter of the electrospun fiber mats were analyzed by using scanning electron microscopy (SEM). The composite structure was characterized by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FT-IR). SEM images showed that the morphology and diameter of the nanofibers were mainly affected by the weight ratio of the blend. Nanofibers were obtained when the CS-EDTA content was less than 50%wt. The average diameter of the nanofibers was 119-223 nm, and this average diameter decreased with increasing CS-EDTA content. In summary, these CS electrospun nanofiber mats may be proper for the drug delivery or wound dressing application.

scholarly journals Synthesis of Novel Nano-Strawberry TiO2 Structures with the Aid of Microwave Inverter System: Growth Time Effect on Optical Absorption Intensity

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Athar Ali Shah
Keyword(s):  
Optical Absorption ◽  
Boric Acid ◽  
Microwave Power ◽  
Average Diameter ◽  
Time Effect ◽  
Growth Time ◽  
High Porosity ◽  
Capping Agent ◽  
Absorption Intensity ◽  
Highly Porous

<p class="western"><span lang="EN-MY">A novel anatase TiO<sub>2</sub> with nanostrawberry-like structure with high porosity has been synthesised on ITO, with the aid of microwave power in a very short duration of 6 minutes. The growth of these novel TiO<sub>2</sub>nanostructures on ITO is attained stoichiometrically by using <em>ammonium hexafluoro titanate, Hexamethylenetetramine, and Boric acid as precursor, capping agent, and reducing agent, respectively</em>. Optical absorption intensity and thickness of these nanostructure layers can be varied by the growth time. A highly porous, 2.25 µm thickest layer has been successfully synthesised on ITO, and the average diameter of these nanostructures was found approximately 70±2.5nm. These highly porous nanostructures are expected to be good candidate for photocatlysis applications and efficient photovoltaic performances of dye sensitised solar cells.</span></p>

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