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This work presents a low-cost and low-temperature wafer-level packaging solution for microelectromechanical systems (MEMS) devices. Heat-sensitive polymer poly(propylene carbonate) is used as the sacrificial material to release the capping layer in a clean and fast manner. Free-standing caps made of amorphous silicon carbide films and as large as 450 µm in diameter are successfully fabricated. To demonstrate the validity of this technology, surface-micromachined Pirani vacuum gauges are fabricated as an example of MEMS devices and encapsulated. Capped Pirani gauges respond to pressure between 1 mTorr and 1 atm. The Pirani gauges are sealed with Parylene C films that exhibit near-hermetic properties and the initial sealing pressure for 300 µm diameter cavities is characterized to be in the range of tens of torr. [ABSTRACT FROM AUTHOR]

We introduce a novel, low-cost and high-performance hot-wire air flow sensor which utilizes a bond-wire as the sensing element. Standard wire-bonding methods are used to form the hot-wire sensor, similar to those used in post-process integrated circuit (IC) packaging, so sensor fabrication is IC-compatible. The bond-wire extends above the surface of the substrate, saving the valuable chip area and allowing the formation of dense arrays of sensors for this and other applications such as inertial sensors. This hair-like hot-wire anemometer offers high accuracy, high sensitivity and wide dynamic range. Fabricated aluminum and platinum wire flow sensors have a measurement range from 1 cm s-1 to 17.5 m s-1, with an accuracy of 0.06% (platinum wire, 3.3 V) in the low flow regime (<50 cm s-1) and 2.5% (aluminum wire, 3.3 V) in the high flow regime (>2 m s-1). [ABSTRACT FROM AUTHOR]

The prediction of interfacial delamination in multi-layered IC packaging has been a rather complex process as it is challenging to quantify the critical energies of interfacial adhesion experimentally. In this study, a combined approach based on molecular dynamics (MD) and finite element method (FEM) simulations is adopted to characterize and predict delamination in an a-Si3N4/Si bilayer system. The necessary material parameters that are required for the interfacial cohesive constitutive relation in FEM simulation are derived by MD simulation rather than experiment. The work of interfacial fracture obtained by the FEM simulation is about 0.11 J m−2. To validate the presented approach, an experimental nanoindentation test is also conducted to measure the work of interfacial fracture which is obtained to be about 0.085 J m−2. The results obtained by the MD-FEM simulations and the experiment show very good agreement. Therefore, the combined approach can also be applied to investigate other bi-materials or even multi-layered systems, thus facilitating the prediction of interfacial delamination and helping to improve the stability and reliability of the 3D multi-layered IC packaging. [ABSTRACT FROM AUTHOR]

The packing density and power capacity of integrated electronics is increasing resulting in higher thermal flux densities. Improved thermal management techniques are required and one approach is to include thermoelectric coolers as part of the integrated circuit. An analysis will be described showing that the supporting substrate will have a large influence on the cooling capacity of the thermoelectric cooler. In particular, for materials with a low ZT figure of merit (for example gallium arsenide (GaAs) based compounds) the substrate will have to be substantially thinned to obtain cooling, which may preclude the use of thermoelectric coolers, for example, as part of a GaAs based integrated circuit. Further, using experimental techniques to measure only the small positive cooling temperature difference (ΔT) between the anode (Th) and the cathode (Tc) contacts can be misinterpreted as cooling when in fact it is heating. [ABSTRACT FROM AUTHOR]