Microelectromechanical systems (MEMS) have been familiar in the field of microelectronics and device technology since 1965, when Harvey C. Nathanson invented the first MEMS device (known as the resonant gate transistor). Since that time, MEMS have represented a prominent field for academic research, with simplified implementations of several devices such as sensors, transducers, actuators, and accelerometers being fabricated. According to MEMS technology, all devices could be fabricated using standard integrated circuit (IC) techniques, with the device?s lateral dimensions normally ranging from a maximum of 500 nm to submicron ranges.

Paradigm Phase Shift: RF MEMS Phase Shifters: An Overview

In this paper, the radio frequency (RF) magnetron sputtering (MS) method was utilized to fabricate multiple sets of the iron film samples under different sputtering powers. With the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM), how the sputtering power affected the structure, morphology and magnetic properties of the iron film was studied. XRD results showed that all Fe films have a polycrystalline bcc structure and (110) preferred orientation. According to the Bragg equation calculation, the larger the sputtering power, the larger the average grain size, which is consistent with the results of AFM particle size analysis. The main reason is that the sputtering power affects the grain growth mode. As the sputtering power increases, it gradually changes from a small island-like growth to a thick columnar growth. However, from the surface morphology and height profile, we saw that the iron film deposited under 230 W had the most uniform grain size distribution and the grain size was relatively small. This is why thin films deposited under this condition have the best soft magnetic properties. The saturation magnetization (Ms) reaches 1566 emu/cm3, coercivity (Hc) is 112 Oe, and squareness ratio (Mr/Ms) is 0.40. Therefore, iron film prepared under 230 W has good comprehensive properties (highest Ms, lower Hc and Mr/Ms) that provide an experimental basis for further thin film research work.

Effect of the Sputtering Power on the Structure, Morphology and Magnetic Properties of Fe Films

A compact radiofrequency (RF) MEMS single-pole double-throw (SPDT) switch based on series capacitive configuration is proposed. The critical process parameters are analyzed to improve the fabrication process. A technique of cold–hot thermal shock for lift-off method is explored. The residual stress in the structure is quantified by lancet test structures that come out to be 51 MPa. Effect of residual stress on actuation voltage is explored, which changes its value from 24 to 22 V. Resonance frequency and switching speed of the switch are 11 kHz and 44  μs, respectively, measured using laser Doppler vibrometer. Measured bandwidth of the SPDT switch is 20 GHz (5 to 25 GHz), which is verified with finite element method simulations in high frequency structure simulator© and an equivalent LCR circuit in advanced design system©. Insertion loss of the switch lies in −0.1 to −0.5  dB with isolation better than −20  dB for the above-mentioned bandwidth.

Fabrication and analysis of radiofrequency MEMS series capacitive single-pole double-throw switch

RF MEMS ohmic switches are prone to stiction and contact degradation. In literature, bumps are made at the contact area to reduce stiction with additional fabrication steps. In this article, ohmic switch based on cantilever configuration is developed without using any additional step. The switch structure is modified to improve its mechanical parameters, such as pull-in voltage and switching speed. The measured switching time of the switch is $1.8~\mu \text{s}$ . A footprint of the developed single pole single throw (SPST) switch is 0.9 mm2. The insertion loss and isolation of the SPST switch are better than 0.8 and 20 dB, respectively. The switch has a wide bandwidth of 10 GHz (dc to 10 GHz). The switch has completed 725 million hot cycles at 1-dBm power.

Improved Design of Ohmic RF MEMS Switch for Reduced Fabrication Steps

Green lean six sigma journey: Conceptualization and realization

A comparison of dry and wet release methods for surface micromachining of metallic structures, such as RF MEMS switches, test structures, bridges, and cantilevers is presented. The dry release process is opti- mized by varying the concentration of O2 and CF4 plasma and RF power. The plasma ashing of the sacrificial layer typically results in damage to metallic structures or stress-related deformation due to rise in temperature (>80°C). A wet release process using critical point drying (CPD) has been investigated to realize gold-electro- plated structures with reduced residual stress. The CPD, being a low-temperature (31.1°C) process, is more suitable for compliant structures without any deformation. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)

Comparative study of various release methods for gold surface micromachining

The modelling and simulation of nanoelectromechanical (NEM) switch is indispensable to get optimum device dimensions. The present work deals with the design and simulation of hinge structure-based ...

Finite Element Analysis of Graphene Oxide Hinge Structure-based RF NEM Switch

This paper outlines the power handling capabilities of metal contact switches The appropriate choice of configuration (inline or offline) reduces the probability of self actuation and allows high input RF power The shape and position of the contact spots decides the current density and accordingly allows the permissible amount of power to flow without causing any failure These two design aspects are taken into consideration and accordingly switch is designed with an insertion: ?01086 dB, isolation: ?325 dB and return loss: ?1807 dB The pull in voltage of the beam is simulated to 19 V Reinforcing of the beam is done to avoid curling of beam, self actuation at high power and to provide optimum contact force (105 µN) in order to reduce contact resistance The power to be handled by the switch is 156 W, when no temperature considerations are taken into account

Design aspect of high power handling applications: metal contact switches

An analog phase shifter based on distributed MEMS transmission line (DMTL) is designed for Ku band applications. Traditional RF MEMS phase shifter comprising 6 switches has limited phase shift of 37.75° due to instability region. A new concept of stopper is incorporated to achieve high phase shift. In the present paper, optimisation of the analog phase shifter is done to increase its phase shift upto 88.63°. Phase shift is a strong function of capacitance ratio which is increased from 1.75 to 2.95. The maximum operating voltage and mechanical resonant frequency for the phase shifter are 16 V and 8.3 KHz, respectively. The switching time is calculated to 56 μs. The simulated insertion loss of the phase shifter is -1.75 dB with return loss of -20.49 dB at 17 GHz. The simulated results are verified with analytical modelling which are in close match.

https://publications.drdo.gov.in/ojs/index.php/dsj/article/download/8377/5011

Design of Reliable Analog DMTL Phase Shifter with Improved Performance for Ku Band Applications

Ruthenium is deposited by DC magnetron sputtering at different powers and is characterized. The effect of sputtering power on the electrical and structural properties of the film is investigated experimentally. High resolution X-ray diffraction is used to characterize the microstructure of Ru films deposited on SiO2 surface. The peak (002) is more sharp and intense with full width at half maximum (FWHM) of 0.37° at 250W. The grain size increases with increase in sputtering power improving the crystallinity of the film. The film deposited at high sputtering power also showed lower resistivity (12.40 µΩ-cm) and higher mobility (4.82 cm2/V.s) as compared to the film deposited at low power. The surface morphology of the film is studied by atomic force microscopy (AFM).

Prachi Jhanwar

Papers

Comparative study of various release methods for gold surface micromachining

Finite Element Analysis of Graphene Oxide Hinge Structure-based RF NEM Switch

Design aspect of high power handling applications: metal contact switches

Design of Reliable Analog DMTL Phase Shifter with Improved Performance for Ku Band Applications

Effect of sputtering power on the growth of Ru films deposited by magnetron sputtering