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Becoming another key technology for system integration, GaAs based millimeter wave antenna is fabricated by MEMS technology, with high permittivity dielectric substrates. To obtain good performance, it is necessary to achieve the equivalent of low dielectric constant of the local area below microstrip patch antenna. The article describes deep etching fabrication and multiple etching with thick photoresist masking to creat air cavity under the microstrip patch which usually has the height from 70% to 80% of the original media substrate, thus it forms the air-mixed media substrate. Especially for precision control of the substrate thickness, use back thinning and high-precision polishing processes. At last realize back cavity depth of 227μm in the GaAs substrate and complete the process of Ka band MEMS patch antenna. The measurement results: the center frequency is 37.9 GHz, bandwidth is 4.4%, radiation efficiency above 50%.

This is mainly due to the high chemical reactivity and spontaneous etching nature of the fluorine radicals towards silicon, and the high volatility of the silicon fluorides as reaction products. Anisotropy can only be achieved by the inclusion of sidewall passivation schemes to the process. The existing approaches to deep reactive ion etching (DRIE) of silicon are distinguished by the way sidewall passivation is achieved, the key to anisotropy and overall performance of the etch process. Cryogenic etching and the so-called Bosch process with alternating etch and passivation cycles are the two most well-known high-aspect-ratio silicon etch processes and are discussed in this paper.

The design and fabrication of MEMS capacitive differential pressure sensor is reported. Silicon membrane is used as movable electrode. Gold metal film on glass is used as fixed electrode. Anodic bonding is used to bond together the silicon and glass to form the capacitive pressure sensor. The measurement capacitance of the sensors is 5.37 pF at an applied pressure of 0 kPa and 7.26 pF and the full operating range of 40 kPa.The ratio of changed to initial capacitance was 0.35. The error of the MEMS capacitive pressure sensor is less than 4‰ full-scale(FS) by using quadratic curve fitting which can meet most application requirements.

In this paper the oxygen plasma dry release process for membrane-bridge RF MEMS switches is studied and several methods are used to improve the dry release process. The residual PR (Photoresist) on the device substrate after different process time are observed and measured in this paper. The measured data shows that the residual PR exponentially reduces with etch time. It is found that the residual PR on the bottom surface of the membrane bridge is more than that on the substrate. The completely released RF MEMS switch using oxygen plasma dry etch process is obtained.

In this paper, a novel RF MEMS switch driven by combs with low insertion loss is presented. The developed SPST RF MEMS switch with a lateral resistive contact and gold structure layer on a silicon substrate has been fabricated by surface micromachining process. The RF performance of the switch indicates an insertion loss below 0.30 dB at 20 GHz, a return loss better than 20 dB and isolation greater than 30 dB. Good RF characteristics have been achieved by the large contact area and a lateral Au-to-Au resistive contact.

We report our efforts towards designing and fabricating capacitive microaccelerometers with flat bottom surfaces free from the notching effects of Deep Reactive Ion Etching (DRIE) based on SOI process. The substrate layer under the device structure is etched and a metal film is deposited to the backside of moving structure for protecting the bottom surfaces so that the stiction problem and notching effects are avoided. The test results demonstrate that SOI accelerometers have been released successfully. The measured sensitivity is 169.1mV/g and the linearity of output is within 0.202%.