We have developed microelectromechanical system (MEMS)-based electrostatic field sensors using Pb(Zr,Ti)O 3 thin films. Multilayers of Pt/Ti/PZT/Pt/Ti/SiO 2 deposited on silicon-on-insulator (SOI) wafers have been fabricated into the sensors through MEMS microfabrication technology. The resonant frequency of the fabricated sensors is within 1700 -1800 Hz. The developed MEMS-based electrostatic field sensors have shown a good linear response to the voltage of an electrified body, which is comparable to that of commercially available electrostatic field sensors.

No abstract

No abstract

The study aims to investigate the possible defects that may occur during imprinting of poly(chloro-p-xylylene) (parylene-C) film (thermal oxidation, delamination, thermal cracking and insufficient filling at the periphery) and to overcome them by modifying the process conditions and mold design. X-ray diffraction (XRD) analyses results for the parylene-C films indicated that higher deposition pressure leads to a lower crystallinity of parylene-C film. By tuning the process conditions and mold design, patterned fields (composed of arrays of 25-mm-high, 10-mm-wide and 1-mm-long lines with 10 mm spacing) in 0.4mm-thick and 20-mm-sized nickel molds could be successfully replicated on 60-mm-thick parylene-C films deposited at both 25 and 45 mTorr. Complete filling over the whole imprint area could be achieved at <270 C with the press force at 2 kN and the press hold time of 900 s with the aid of an implemented dummy pattern. Both thermal cracking and delamination could be avoided, even at 270 C, under the established process conditions and mold design with the help of an adhesion promotion treatment of silicon substrates (SF 6 plasma etching for 2 min and spin-coating of KBM-503-based solution). Furthermore, the molds used for paryelne imprinting could be cleaned by dipping in chloronaphthalene solution at >175 C, followed by an oxygen plasma etching.

This study demonstrates a replication process for metallic micro mold that combines poly-chloro-p-xylylene (parylene-C) hot-embossing and electroplating techniques. First, the replication characteristics of parylene-C were investigated and compared with those of poly-methyl-methacrylate (PMMA) in terms of the dimensional accuracy of replication. For a given mold (aspect ratio 1:1), the complete filling conditions were 150 °C–50 kgf–200 s for PMMA and 260 °C–200 kgf–900 s for parylene-C, respectively, implying the significantly better durability and heat resistance of parylene-C. The results of surface topological analysis revealed that the dimensional deviation between the mold and the resulting embossed profiles was <2.94% for PMMA and <2.32% for parylene-C, indicating that a hot-embossed parylene-C could be an alternative master for electroplating. Then, a micro-patterned parylene-C master was prepared by hot-embossing with a mold (aspect ratio 1:2.5) and was applied to metallic mold replication. The patterned fields composed of lines of structures in the Ni mold with 25 µm height and 10 µm width/spacing were successfully replicated on parylene-C with a dimensional deviation of about 1.4%. The electroplated Cu successfully filled parylene-C replica master patterns with an aspect ratio of 2.5 without void formation by both adding organic addictives and controlling the seed layer thickness. After electroplating, the Cu micro mold could be successfully separated from the parylene-C replica master.