Thin Film Encapsulation of Radio Frequency (RF) Microelectromechanical Systems (MEMS) Switches

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission line into and out of the package are designed and assessed. Ten different encapsulation designs were created and their RF performance was characterized in terms of insertion loss, return loss, and isolation. A switch without an encapsulation and a switch with a dielectric encapsulation were fabricated and tested by the Air Force Research Laboratory (AFRL), and the test data was used to verify the data from analytical modeling and electromagnetic simulation performed in this work. All results were used to design an optimized encapsulation. An RF MEMS switch with this encapsulation was shown to have an overall insertion loss of less than -0.15 dB at 20 GHz compared to an unencapsulated switch insertion loss of about -0.1 dB. The isolation of the switch was slightly improved with the encapsulation. The fabrication process proposed to manufacture these encapsulations uses a low temperature solder as the metal encapsulation layer. As the final step in the fabrication, the solder is brought to melting temperature and reflowed over the etch holes to form a hermetic encapsulation

IMECE2011-63112 CLOSED FORM SOLUTIONS FOR THE PROBLEM OF STATICAL BEHAVIOR OF NANO/MICROMIRRORS UNDER THE EFFECT OF CAPILLARY FORCE AND VAN DER WAALS FORCE

ABSTRACT The current paper deals with the problem of static instability of Micro/Nano mirrors under the combined effect of capillary force and van der Waals force. First the governing equations of the statical behavior of Micro/Nano mirrors under the combined effect of capillary force and casimir force is obtained using the newtons first law of motion. The dependence of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that existence of vdW torque can considerably reduce the stability limits of the nano/micromirror. It is also found that rotation angle of the mirror due to capillary force highly depends on the vdW toque applied to the mirror. Finally analytical tool Homotopy Perturbation Mehtod (HPM) is utilized for prediction of the nano/micromirror behaviour under combined capillary and vdW force. It is observed that a sixth order perturbation approximation accurately predicts the rotation angle and stability limits of the mirror. Results of this paper can be used for successful fabrication of nano/micromirrors using wet etching process where capillary force plays a major role in the system

IMECE2011-63108 ANALYTICAL SOLUTIONS FOR THE STATIC INSTABILITY OF MICRO/NANO MIRRORS UNDER THE COMBINED EFFECT OF CAPILLARY FORCE AND CASIMIR FORCE

ABSTRACT This paper deals with the problem of static instability of Micro/Nano mirrors under the combined effect of capillary force and Casimir force. At the First the governing equations of the statical behavior of Micro/Nano mirrors under the combined effect of capillary force and casimir force is obtained. The dependency of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that existence of casimir force can considerably reduce the stability limits of nano/micromirror. It is also found that rotation angle of the mirror due to capillary force highly depends on the casimir force applied to the mirror. Finally analytical tool Homotopy Perturbation Method (HPM) is utilized for prediction of the mirror's behaviour under combined capillary and casimir forces. It is observed that a sixth order perturbation approximation accurately predicts the rotation angle and stability limits of the mirror. Results of this paper can be used for successful fabrication of nano/micromirrors using wet etching process where capillary force plays a major role in the system.

CMOS compatible solidly mounted resonator for air quality monitoring

Air pollution has become a growing concern around the world. Human exposure to hazardous air pollutants is associated with a range of health problems and increased mortality. An estimated 40,000 early deaths per year are caused by the exposure to air pollutants in the UK alone, which cost over £20 billion annually to individuals and health services1. In this work, novel solidly mounted resonator (SMR) devices were developed for integration in a low-cost, portable air quality monitor for the real-time monitoring of particulate matter and volatile organic compounds (VOCs). Finite element models of the SMRs were developed to aid their design and simulate the response of the sensors to particles and exposure to VOCs. For particle sensing, a SMR based unit was developed, working in a dual mode configuration. The unit was characterised inside an environmental chamber, together with commercial reference instruments, to particles of known size and composition. A detection limit of 20 μg/m3 was found (below the safe exposure limit). To target fine particles (<2.5 μm), a virtual impactor was incorporated into the system. For VOC detection, the SMR devices were functionalised with polymer coatings to detect acetone and toluene vapours (most common VOCs in air). A polymer drop-coating system was developed to complete this aim (polymer film thicknesses <100nm). An automated VOC test station was developed to characterise the SMR based sensors to low ppm concentrations of the target vapours (<200 ppm). The SMR devices demonstrated a limit of detection of 5 ppm to toluene and 50 ppm of acetone (well below the safe exposure limits). A novel CMOS based SMR device, suitable for volume production and monolithic integration, was designed with an integrated microheater and CMOS acoustic mirror. The heater was included to vary the temperature of the sensing area (to enhance the sensitivity of the SMR to a particular VOC through temperature modulation or to clear particles off the surface). The fabricated device (1.9 GHz) exhibited good performance

Physical Aspects of VLSI Design with a Focus on Three-Dimensional Integrated Circuit Applications

This work is on three-dimensional integration (3DI), and physical problems and aspects of VLSI design. Miniaturization and highly complex integrated systems in microelectronics have led to the 3DI development as a promising technological approach. 3DI offers numerous advantages: Size, power consumption, hybrid integration etc., with more thermal problems and physical complexity as trade-offs. We open this work by presenting the design and testing of an example 3DI system, to our knowledge the first self-powering system in a three-dimensional SOI technology. The system uses ambient optical energy harvested by a photodiode array and stored in an integrated capacitor. An on-chip metal interconnect network, beyond its designed role, behaves as a parasitic load vulnerable to electromagnetic coupling. We have developed a spatially-dependent, transient Green's Function based method of calculating the response of an interconnect network to noise. This efficient method can model network delays and noise sensitivity, which are involved problems in both planar and especially in 3DICs. Three-dimensional systems are more susceptible to thermal problems, which also affect VLSI with high power densities, of complex systems and under extreme temperatures. We analytically and experimentally investigate thermal effects in ICs. We study the effects of non-uniform, non-isotropic thermal conductivity of the typically complex IC material system, with a simulator we developed including this complexity. Through our simulations, verified by experiments, we propose a method of cooling or directionally heating IC regions. 3DICs are suited for developing wireless sensor networks, commonly referred to as ``smart dust.'' The ideal smart dust node includes RF communication circuits with on-chip passive components. We present an experimental study of on-chip inductors and transformers as integrated passives. We also demonstrate the performance improvement in 3DI with its lower capacitive loads. 3DI technology is just one example of the intense development in today's electronics, which maintains the need for educational methods to assist student recruitment into technology, to prepare students for a demanding technological landscape, and to raise societal awareness of technology. We conclude this work by presenting three electrical engineering curricula we designed and implemented, targeting these needs among others

Factories of the Future

Engineering; Industrial engineering; Production engineerin

Smart Technologies for Precision Assembly

This open access book constitutes the refereed post-conference proceedings of the 9th IFIP WG 5.5 International Precision Assembly Seminar, IPAS 2020, held virtually in December 2020. The 16 revised full papers and 10 revised short papers presented together with 1 keynote paper were carefully reviewed and selected from numerous submissions. The papers address topics such as assembly design and planning; assembly operations; assembly cells and systems; human centred assembly; and assistance methods in assembly

Factories of the Future

Engineering; Industrial engineering; Production engineerin