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Abstract: We present a new capacitive type surface micromachined MEMS microphone with improved sensitivity and frequency response. In contrast to the bulk micromachined MEMS microphones, the surface MEMS microphone shows advantages of CMOS compatibility and no backside etching process . However, the shallow back chamber depth and the small sensing gap of the surface MEMS microphone increase the air damping on the sensing membrane and reduce the overall sensitivity. In this paper, we proposed the center-hole membrane. The proposed center-hole on the sensing membrane reduces the air damping at the center and increases the membrane displacement. The fabricated surface MEMS microphone with center-hole membrane shows an improved sensitivity and frequency response. The displacement of center-hole membrane is increased to 168% for 500μm diameter membrane and 172% for 700μm diameter membrane at 10kHz, with an equivalent acoustic pressure of 1Pa and a bias of 6V. [Copyright &y& Elsevier]

A new technique for highly controllable trench corner rounding (TCR) at top and bottom of the trench using pull-back and hydrogen annealing has been developed and investigated. The pull-back process combined with hydrogen annealing can control the TCR radius at the top corners of the trench. The silicon migration generated by hydrogen annealing at the trench corners provides (1 1 1) and (3 1 1) crystal planes and gives a uniform gate-oxide thickness, resulting in highly reliable trench gate DMOSFETs with high breakdown voltages and low leakage currents. The gate breakdown voltage of a trench DMOSFET fabricated by using hydrogen annealing was 27 V, which was 22% higher than that of no hydrogen-annealed devices. The on-resistance of the trench gate DMOSFET fabricated by using the trench cell of 45,000 is about 55 mΩ at a gate voltage of 10 V under a drain current of 5 A. [Copyright &y& Elsevier]

Abstract: A Li-ion based stacked-type potentiometric solid-state (S-PSS) sensor was designed and fabricated to detect carbon dioxide (CO2) on an alumina substrate in an indoor environment using mass production techniques. This design can reduce 70% of the active area compared to a planar-type potentiometric solid-state (P-PSS) sensor, as a reference material is not required. All deposition materials used in the sensor were screen-printed except for the electrolyte, which was deposited using thermal evaporation. The prepared materials were characterized through an X-ray diffraction analysis and scanning electron microscopy. The gas response characteristics of the S-PSS and P-PSS were examined a temperature range of 350–500°C and for CO2 gas concentrations of between 16 and 5000ppm. The S-PSS sensor showed a response of 40–90mV/dec, which is similar to the P-PSS sensor performance at the same operating temperatures. The response and recovery times of the S-PSS were about 2 and 4s, respectively. Repeated measurements showed a very good consistency of within 5mV in a full measurement range. [Copyright &y& Elsevier]

The dilational rheological behavior of gelatin molecules adsorbed at the air-water interface has been studied as a function of sodium dodecyl sulfate (SDS) concentration for a 7 wt % gelatin-SDS solution at 40 degrees C. Binding of SDS molecules to the gelatin strands disrupts the cross-linked network structure of adsorbed gelatin molecules and results in a reduction of the surface elastic modulus of the adsorbed layer that continues until the bulk SDS concentration reaches 1 mM. Beyond this SDS concentration, the dilational rheological properties of the adsorbed gelatin layer are indistinguishable from those of pure SDS adsorbed layers.