Down-state Capacitance Research Articles

Modelling, Fabrication and Testing of RF Micro-Electro-Mechanical-Systems Switch

This paper presents an approach to evaluate capacitance developed by perforated membrane of RF MEMS switch with high accuracy. An analytical model is developed for both upstate and downstate of switch by including parasitic and fringing field capacitance in parallel plate capacitance model. The proposed analytical model includes the ligament efficiency term directly in the formula which reduce the efforts to calculate it individually for various perforation sizes. The capacitance analysis has been carried out by varying the physical parameters to optimize the switch dimensions and these analytical results are compared with the simulation results carried out by 3D FEM tool COMSOL multiphysics for validation. The proposed analytical model results are then compared with benchmark models to understand the efficiency of proposed model in estimating the up and downstate capacitances. The proposed analytical model proved to be good with less error percentage of 2.13% at upstate and 2.59% at downstate whereas the other benchmark models gives greater than 5% error. The switch is then fabricated using 4-mask surface micromachining process and experimental evaluation of capacitance at both upstate and downstate is carried out by DC probe station. Experimentally, the upstate capacitance is obtained as 37.4 fF and downstate as 2.43 pF and the analytical models exhibited low error percentage of 3.95% at upstate and 2.05% at downstate condition for μ=0.5.

Design and Fabrication of a Ka Band RF MEMS Switch with High Capacitance Ratio and Low Actuation Voltage.

In this paper a high capacitance ratio and low actuation voltage RF MEMS switch is designed and fabricated for Ka band RF front-ends application. The metal-insulator-metal (MIM) capacitors is employed on a signal line to improve the capacitance ratio, which will not degrade the switch reliability. To reduce the actuation voltage, a low spring constant bending folding beam and bilateral drop-down electrodes are designed in the MEMS switch. The paper analyzes the switch pull-in model and deduces the elastic coefficient calculation equation, which is consistent with the simulation results. The measured results indicated that, for the proposed MEMS switch with a gap of 2 μm, the insertion loss is better than −0.5 dB and the isolation is more than −20 dB from 25 to 35 GHz with an actuation voltage of 15.8 V. From the fitted results, the up-state capacitance is 6.5 fF, down-state capacitance is 4.3 pF, and capacitance ratios is 162. Compared with traditional MEMS capacitive switches with dielectric material Si3N4, the proposed MEMS switch exhibits high on/off capacitance ratios of 162 and low actuation voltage.

Design and Analysis of a Non-Uniform Meander RF MEMS Switch

This paper aimed to design and analysis of non-uniform meander capacitive shunt RF MEMS switch. The less pull in voltage is obtained in flexure type membrane by proposed RF MEMS Switch. The selection of materials for the beam and dielectric layer is expressed in this paper and also shown the performance depends on materials utilized for the design. The high isolation of -31.15dB actuating at the pull-in voltage of 7.69V with a spring constant of 3.28N/m produced the switch and is obtained by the optimization process. Capacitive contact switches have capability of power handling. The actuated switch state provides an excellent isolation. It shorts the ground by RF signal. MEMS technology is the integration of electrical and mechanical components on single platform i.e. substrate [10]. From the literature, various researchers have proposed different RF MEMS Switch, but still there few challenges on optimization of the Switch for best performance. The electromechanical analysis such as Upstate, Downstate capacitances and stress analysis have been carried out. The performance of the switch is analyzed by taking appropriate materials selected by Ashby’s approach. These optimized dimensions are feasible to fabricate. The substrate height, material for the substrate and coplanar waveguides are used for the impendence matching. For obtaining the less pull in voltage overlapping area is to be increased.

Design of a Non-uniform Serpentine Asymmetric Cantilever RF-MEMS Shunt Capacitive Switch for RADAR Applications

This paper presents the design and simulation of Cantilever type RF-MEMS Capacitive shunt switch with meanders and perforations. The main objective of this paper is to reduce the pull-in voltage and increases isolation of the proposed switch. Electro-mechanics and Solid-mechanics are used to simulate the proposed switch by using COMSOL Multiphysics software. The capacitance, switching time, stress analysis are calculated and compare both theoretical and simulation results of the proposed switch. By varying different beam thickness, materials, an air gap between the beam and signal line to calculate spring constant and pull-in voltage. The proposed switch having pull-in voltage is 1.371 V, the dielectric material Si3N4 is to improve the capacitance analysis of the switch. The up and downstate capacitance is 7.073 fF, 1.259 pF. The RF performance is simulated by using Ansoft HFSS tool, the switch performs at low frequencies at 1–4 GHz range. The return (S11) and insertion loss (S12) of the proposed switch is − 30 dB, − 0.0516 dB and the switch having good isolation (S21) is − 37.5 dB at 1.5 GHz frequency. The switch is suitable for radar and satellite communication applications.

Design and simulation of capacitive SPDT RF MEMS switch to improve its isolation

This paper presents the simulation and analysis of capacitive shunt SPDT RF MEMS switch for high radio frequency applications. The design is based on the shunt configuration consisting of 2 capacitive type switches. To reduce pull in voltage, the high-frequency capacitive SPDT switch is proposed. The beam is designed with non-uniform meanders with perforations. By using the COMSOL Multiphysics tool, we found the pull-in voltage as 1.5 V at a beam thickness of 0.5 μm. The corresponding capacitance ratio is 44 for the dielectric of Silicon Nitrate. The up sate and downstate capacitance of the switch is calculated and simulated. The performance analysis is done by using HFSS tool and is found to RF-perform excellently at 28 GHz with isolation of − 68 dB, the return and insertion losses are − 61 dB and − 0.1 dB respectively.

Surface roughness effects on electromechanical performance of RF-MEMS capacitive switches

The effect of surface roughness on the electromechanical performance of radio frequency micro-electromechanical system (RF-MEMS) based capacitive switches is an important reliability concern. This paper presents a finite element method (FEM) based simulation methodology for the estimation of surface roughness effects on the electromechanical characteristics of parallel plate capacitive RF-MEMS switch. The important electromechanical characteristics considered for the analysis of surface roughness effect include up-state capacitance, down-state capacitance, pull-in voltage, pull-in gap and switching time of RF-MEMS switch. A simple roughness model is employed consisting of semi-circles of constant radius along the surface of an RF-MEMS switch. It is shown that there are significant, but predictable shifts in electromechanical characteristics of RF-MEMS switch due to surface roughness. The results illustrate that the normalized value of up-state capacitance and pull-in gap increases, whereas the values of downstate capacitance, pull-in voltage and switching time decreases with an increase in surface roughness. The change in pull in voltage for an initial air gap of 0.4μm and roughness of 50nm is around 28.5% which is about quarter the value of voltage required for the actuation of smooth surface RF-MEMS switch. The results obtained through FEM based analysis in this work are in good agreement with the adopted analytical model and experimental results presented in literature.

Analysis of a novel RF MEMS switch using different meander techniques

In this paper, two types of RF MEMS switches namely step structure and Normal beam structure are designed and analyzed using different meander techniques. Three techniques namely plus, zigzag and three-square meander were used to lower the pull-in voltage. The actuating beam is designed with the rectangular perforations affects the performance of a switch by lowering the pull-in voltage, switching speed and results in better isolation. In this paper a comparative analysis is done for all three meander techniques with and without perforations on the beam. Total six structures have been designed with the combination three meanders and two different beam structures. The proposed stepdown structure exhibits high performance characteristics with a very low pull-in voltage of 1.2 V having an airgap of 0.8 µm between the actuation electrodes. The gold is used as beam material and HfO2 as the dielectric material such that the upstate and downstate capacitance is seen as 1.02 fF and 49 fF. The FEM analysis is done to calculate the spring constant and thereby the pull-in voltage and behavior of the switch is studied with various parameters. The switch with a step structure and three-square meander configuration has shown best performance of all by requiring a pull-in voltage of 1.2 V and lower switching time of 0.2 µs. The proposed switch also exhibits good RF performance characteristics with an insertion loss below − 0.07 dB and return loss below − 60 dB over the frequency range of 1–40 GHz. At 28 GHz a high isolation of − 68 dB is exhibited.

Design of a novel structure capacitive RF MEMS switch to improve performance parameters

This study reports the design and analysis of novel step structure RF micro-electromechanical system (MEMS) switch for low pull-in voltage, low insertion loss and high isolation by using uniform single meander. The central beam of the membrane is designed with 0.5 µm lower than the side beams to form a step-down structure which reduces the pull-in voltage. Stress analysis, electromechancial, switching time, quality factor and RF analysis have done to understand the behavioural characteristics of the proposed step-down switch. The analysis has been carried out for different beam and dielectric materials among them switch with gold material exhibits low pull-in voltage of 4.7 V, low insertion loss <1 dB and high isolation of −38.3 dB at 28.2 GHz for silicon nitride. The switch also shows good quality factor of 0.95 for gold material along with high capacitance ratio of 132. The upstate capacitance of 56.8 pF contributes low return loss and made the switch to transmit the signal up to 26.2 GHz and provides 7.2 pF of downstate capacitance to produce high isolation at 26.2 GHz which is efficiently used for K-band satellite applications.

Design and simulation of a novel RF MEMS shunt capacitive switch with a unique spring for Ka-band application

RF-MEMS switches may be divided into capacitive and metal-to-metal types in terms of type of connection. In capacitive switches in the OFF-state the beam does not attach to the transmission line due to the presence of a thin dielectric layer and it gets released easily. Capacitive switches are better compared with the metal-to-metal types due to their ability to transmit signals of higher frequency and power. In this paper, a novel RF MEMS shunt capacitive switch with a unique spring design is proposed. The proposed design benefits from high isolation, low loss, low actuation voltage, small size and weight compared to similar switches and is designed for application in the Ka-band. Step structure is used in the mechanical design of the switch to reduce the air gap between the bridge and the transmission line that has resulted in reduction of actuation voltage to 2.2 V. The proposed switch has been placed upon a coplanar waveguide (CPW) line with an impedance of 50 Ohms. $${\text{SiO}}_{2}$$ with a thickness of 1000 A has been used as dielectric to increase isolation and down-state capacitance. The unique design of the spring results in the reduction of stress to a minimum at all points of the switch especially the springs at the time of applying the actuation voltage. This advantage would reduce switch failures as time passes and results in increased life of the switch. Up-state capacitance is 93.3 fF and down-state capacitance is 2.64 pF. Therefore, a capacitive ratio of 28 is obtained. The dynamic behavior of the switch is studied by using the COMSOL Multiphysics software package and the RF characteristics have been obtained by using the HFSS software and show good RF performance. The results show that in the up-state, the designed switch including S11 is less than − 11.5 dB and S21 is more than − 0.85 dB at 1–40 GHz. In the down-state, the switch has excellent isolation in the Ka-band. Maximum isolation is − 71 dB that occurs at the resonance frequency of 30.5 GHz.

Performance analysis of series: shunt configuration based RF MEMS switch for satellite communication applications

In this paper the RF-MEMS switch with series–shunt configuration on a single quartz substrate is presented to achieve high isolation than the individual series or shunt switches. This paper presents the isolation of series–shunt configuration switch of 84.7 dB is achieved at 26 GHz when both switches are in OFF state which is higher than the OFF state of the individual series switch and shunt switches. The return loss (s11) is less than − 60 dB, insertion loss is less than − 0.09 dB is observed for better performance in satellite communication applications. The series/ohmic and shunt/capacitive membranes are designed with uniform spring structure and crab leg structure, respectively and simulated using FEM tool. Ashby’s method is used to select the materials for the switch membranes/beam and dielectric layer. The gap between the dielectric and the movable beam is maintained at 3 µm in series switch and 2.5 µm for shunt switch to achieve same pull-in voltage of 23.5 V. The up-state and down-state capacitance of the device is calculated and compared with the simulated results which are 0.24 and 14.2 fF, respectively by considering TiO2 as a dielectric layer between membrane and lower electrode.

Novel RF MEMS capacitive switches with design flexibility for multi-frequency operation

RF MEMS capacitive shunt switches with a dielectric-on-metal (DOM) capacitor, which are widely used for microwave applications in the communication field, suffer from some serious drawbacks. A significant shift is observed in the resonant frequency of these switches due to the reduction in the down-state capacitance caused by the surface roughness of the dielectric layer. In order to achieve accurate down-state capacitance, a thin layer of floating metal is deposited on the dielectric layer converting the DOM switch to a metal-insulator metal (MIM) switch. The MIM switch opens up interesting possibilities in the design, such as achieving flexibility in the operating frequency of the switch. This paper reports a novel method to achieve design flexibility for multi-frequency operation in switches, by effectively utilizing the equipotential nature of the floating metal in the MIM capacitor. Unlike in a DOM switch, the resonant frequency can be varied by changing merely the length of the floating metal, without having to make any other structural modifications. This enables to have switches operating at different frequency on the same wafer. The beams of the switches are also designed in such a way as to provide stress resilience, thereby preventing buckling. This paper presents the design, simulation, fabrication and characterization of a switch that operates in the X-band. The fabricated switches show excellent stress resilience. The characterized switch demonstrates a reduction in the resonant frequency in proportion to an increase in the length of the floating metal, hence validating the design flexibility proposed in this paper.

Design and performance analysis of uniform meander structured RF MEMS capacitive shunt switch along with perforations

This paper presents design and simulation of uniform structured RF MEMS capacitive shunt switch using FEM tool and HFSS software. The switches with different shaped meanders and perforations which result in less spring constant, less pull-in voltage, high isolation loss, high switching speed and low insertion loss have been designed. From the simulated results it is observed that the rectangular perforations gives the better results, when compared with square and cylindrical shaped perforations. Comparative study is done for zigzag, plus and three square shaped meander along with rectangular perforations on each structure. When the gap between the dielectric and the movable beam is 0.8 µm, the up state capacitance for HfO2 is 4.06fF and for Si3N4 is 3.80fF. The downstate capacitance for HfO2, Si3N4 is 49fF, 26.9fF respectively. The capacitance ratio is 120.6. Poly-tetra-fluoro-ethylene material is given for the movable beam whose young’s modulus is 0.4 GPa and the spring constant is calculated theoretically for each structure; by using this the pull in voltage and the settling time are calculated. Step switch with three square Meander has switching time 10.25 µs, pull in voltage as 2.45 V. By using HFSS 3-D electromagnetic model we observed the return loss (S11) is less than −60 dB, the insertion loss is less than −0.07 dB in the range of 1–40 GHz frequency and switch isolation (S21) is −61 dB at 28 GHz frequency.

Effect of surface asperities on the capacitances of capacitive RF MEMS switches

The effects of surface asperities on the up- and down-state capacitances of the capacitive radio frequency (RF) micro electromechanical system (MEMS) switches were studied in this paper based on the single asperity model and statics. The research results demonstrated that surface asperities effects on the up-state capacitance could be neglected, whereas surface asperities must be taken into consideration at the down-state position in the RF MEMS switches because the surface asperities significantly affected the down-state capacitance. The down-state capacitance typically decreased as the root mean square (RMS) roughness and asperity radius increased. The down-state capacitance was approximately 26% of the theoretical value when the RMS roughness was 20 nm, and 32% of the theoretical value when the asperity radius was 100 nm. The experimental results were in good agreement with the simulation results.

Study of the Effect of Surface Roughness on the Performance of RF MEMS Capacitive Switches Through 3-D Geometric Modeling

Surface roughness is an important factor that influences the reliability and performance of radio frequency microelectromechanical systems switches. The presence of surface roughness impedes a perfect contact in the down-state condition of the switch which in turn affects the following parameters—resonant frequency, down-state capacitance, and isolation at resonance. The result is a significant deviation from the electromagnetic characteristics simulated by assuming flat surfaces making a perfect contact. However, creating a rough topography manually is cumbersome. A Visual Basic Script code for generating rough surfaces of any average value and standard deviation has been developed. The code runs on High Frequency Structure Simulator platform. This paper focuses on the simulations that include the effect of surface roughness on both the beam and the dielectric layer using a 3-D geometric model by representing surface asperities as an array of pyramids, the heights of which follow a Gaussian distribution. This assumption takes into account of the statistical nature of surface roughness. The results of simulation indicate that the presence of surface roughness reduces down-state capacitance and isolation and shifts the resonant frequency from the X-band (8–12 GHz) for which it was originally designed.

Design and simulation of a novel RF MEMS shunt capacitive switch with low actuation voltage and high isolation

This paper presents a new RF MEMS capacitive shunt switch with low voltage, low loss and high isolation for K-band applications. In this design, we have proposed the step structure to reduce the air gap between the bridge and the signal line, thus the actuation voltage is reduced to 2.9 V. Furthermore, to reach more isolation, we used aluminum nitride (AlN) as a dielectric layer instead of conventional dielectric materials such as $$Sio_{2}$$Sio2 and $$Si_{3} N_{4}$$Si3N4 which has more $$\varepsilon_{r}$$?r led to increase the down-state capacitance and increase the isolation of switch. Moreover, to reach more isolation, a kind of meander have designed to increase the inductance of switch, therefore, the resonant frequency is shifted to the desired frequency band. The results show that the switch in up position involve $$S_{11}$$S11 less than ?10 dB from 1 to 40 GHZ and $$S_{21}$$S21 more than ?0.72 dB from 1 to 22 GHZ. In down state, switch has an excellent isolation at the frequency range of K-band. The maximum isolation of ?58 dB is obtained at resonance frequency of 27 GHZ.

Effects of Contact Roughness and Trapped Free Space on Characteristics of RF-MEMS Capacitive Shunt Switches

Dielectric surface roughness and top electrode metal asperities tend to affect both the lifetime reliability and the frequency response of radio frequency microelectromechanical systems (RF-MEMS) capacitive shunt switches. The downstate (OFF) capacitance of these switches is considerably affected by the interface irregularities and the free space trapped between the contacting surfaces of a MEMS switch. Attempts have been made to develop models to describe the effects of interface roughness and the trapped free space, yet no comprehensive model, including closed form analytical equations, still exists. A very large body of research has been conducted in physics to model the types of surface fluctuations and interface irregularities between two contacting media. Among these models, the self-affine fractals can be used to describe different growth and deposition techniques, such as sputtering, thermal evaporation, and molecular bean epitaxy. Based on this concept, in this paper, we developed a model that incorporates the effects of contact roughness and free space into classic equations describing the electromechanical behavior of a capacitive MEMS switch. The resulting closed form equations can properly predict the electrostatic and mechanical characteristics of a typical RF-MEMS switch. Measurement and test results from the reported works are used to confirm the validity of the model.

A modified capacitance model of RF MEMS shunt switch incorporating fringing field effects of perforated beam

This paper deals with the approach to accurately model the capacitance of non-uniform meander based RF MEMS shunt switch with perforated structure. Here the general analytical model of capacitance is proposed for both up state and down state condition of the switch. The model also accounts for fringing capacitance due to beam thickness and etched holes on the beam. Calculated results are validated with the simulated results of full 3D FEM solver Coventorware in both the conditions of the switch. Variation of Up-state and Down-state capacitances with different dielectric thicknesses and voltages are plotted and error of analytical value is estimated and analyzed. Three benchmark models of parallel plate capacitance are modified for MEMS switch operation and their results are compared with the proposed model. Percentage contribution of fringing capacitance in up-state and down-state is approx. 25% and 2%, respectively, of the total capacitance. The model shows good accuracy with the mean error of −4.45% in up-state and −5.78% in down-state condition for a wide range of parameter variations and −2.13% for ligament efficiency of μ=0.3.

介电层粗糙对电容式RF MEMS开关down态电容退化的影响

Capacitive RF MEMS switch will latch at high power RF signal handling situations. Due to the roughly contact between the switch membrane and the dielectric layer, the down-state capacitance of the switch degrades. The high-fidelity analytical computation model of the latching failure threshold power for a capacitive RF MEMS switch is very hard to establish. The comparative modelling method between a 3D electromagnetic simulation and an equivalent circuit simulation is proposed. First of all, the 3D electromagnetic simulation model is established. The simulation curve of the switch isolation (S21) is got at different surface roughness. And then the equivalent circuit model of the same switch is established. The simulation curve of the S21 of the switch equivalent circuit and the simulation result of the 3D electromagnetic are matched by tuning the down-state capacitance in the equivalent circuit. The set of function relationship between the surface roughness of dielectric layer and the down-state capacitance is identified. And the function relationships between the surface roughness of dielectric layer and the degradation of down-state capacitance are identified by changing the surface roughness level of dielectric layer and repeating the above steps. The rationality of the method is verified by comparing the calculated values of the down-state capacitance with the measured values in related literature. The analytical formula of latching failure threshold power of the switch with smooth dielectric layer is revised using the function relationships between the surface roughness of dielectric layer and the degradation of down-state capacitance to predict the power handling capacity of the switch with rough dielectric layer.

RF MEMS Shunt Capacitive Switches Using AlN Compared to $\hbox{Si}_{3}\hbox{N}_{4}$ Dielectric

RF microelectromechanical systems (MEMS) capacitive switches for two different dielectrics, aluminum nitride (AlN) and silicon nitride <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(\hbox{Si}_{3}\hbox{N}_{4})$</tex></formula> , are presented. The switches have been characterized and compared in terms of DC and RF performance (5–40 GHz). Switches based on AlN have higher down-state capacitance for similar dielectric thicknesses and provide better isolation and smaller insertion losses compared to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{Si}_{3}\hbox{N}_{4}$ </tex></formula> switches. Experiments were carried out on RF MEMS switches with stiffening bars to prevent membrane deformation due to residual stress and with different spring and meander-type anchor designs. For a <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim$</tex></formula> 300-nm dielectric thickness, an air gap of 2.3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> and identical spring-type designs, the AlN switches systematically show an improvement in the isolation by more than <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex> </formula> 12 dB ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 35.8 dB versus <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 23.7 dB) and a better insertion loss ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 0.68 dB versus <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 0.90 dB) at 40 GHz compared to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{Si}_{3}\hbox{N}_{4}$</tex></formula> . DC measurements show small leakage current densities for both dielectrics ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$&lt;10^{-8}\ \hbox{A/cm}^{2}$</tex> </formula> at 1 MV/cm). However, the resulting leakage current for AlN devices is ten times higher than for <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{Si}_{3}\hbox{N}_{4}$</tex></formula> when applying a larger electric field. The fabricated switches were also stressed by applying different voltages in air and vacuum, and dielectric charging effects were investigated. AlN switches eliminate the residual or injected charge faster than the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{Si}_{3}\hbox{N}_{4}$</tex></formula> devices do. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hfill$</tex></formula> [2011-0359]

Estimation of RF performance from LF measurements: Towards the design for reliability in RF-MEMS

This paper presents a method which allows the prediction of the RF performance of capacitive RF-MEMS by measuring the UP and DOWN state capacitances. The method is based on the combined use of a very accurate lumped element equivalent circuit model and wafer level measurements of the capacitances in two different states. This approach allows very fast monitoring of the complete RF performance in the entire band, at the cost of a simple (LF) capacitance measurements and an equivalent circuit model extraction. The results presented here demonstrate the efficiency of this technique in tracking or predicting deviation due to manufacturing process dispersions or other device features difficult to account for experimentally.