A comprehensive high-level model for CMOS-MEMS resonators

2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a behavioral modeling technique for CMOS microelectromechanical systems (MEMS) microresonators that enables simulation of an MEMS resonator model in Analog Hardware Description Language format within a system-level circuit simulation. A 100-kHz CMOS-MEMS resonant pressure sensor has been modeled into Verilog-A code and successfully simulated within Cadence framework. Analysis has shown that simulation results of the reported model are in agreement with the device characterization results. As an application of the proposed methodology, simulation and results of the model together with an integrated monolithic low-noise amplifier is exemplified for detecting the position change of the resonator.Peer ReviewedPostprint (author's final draft

CMOS-MEMS resonant pressure sensors: optimization and validation through comparative analysis

The final publication is available at Springer via http://dx.doi.org/10.1007/s00542-016-2878-3An optimized CMOS-MEMS resonant pressure sensor with enhanced sensitivity at atmospheric pressure has been reported in this paper. The presented work reports modeling and characterization of a resonant pressure sensor, based on the variation of the quality factor with pressure. The relevant regimes of air flow have been determined by the Knudsen number, which is the ratio of the mean free path of the gas molecule to the characteristic length of the device. The sensitivity has been monitored for the resonator design from low vacuum to atmospheric levels of air pressure. This has been accomplished by reducing the characteristic length and optimization of other parameters for the device. While the existing analytical model has been adapted to simulate the squeeze film damping effectively and it is validated at higher values of air pressure, it fails to compute the structural damping mechanisms dominant in the molecular flow regime, i.e. at lower levels of air pressure. This discrepancy has been solved by finite element modeling that has incorporated both structural and film damping effects. The sensor has been designed with an optimal geometry of 140 × 140 × 8 µm having 6 × 6 perforations along the row and column of the plate, respectively, for maximum Q, with an effective mass of 0.4 µg. An enhanced quality factor of 60 and reduced damping coefficient of 4.34 µNs/m have been obtained for the reported device at atmospheric pressure. The sensitivity of the manufactured device is approximately -0.09 at atmospheric pressure and increases to -0.3 at 40 kPa i.e. in the lower pressures of slip flow regime. The experimental measurements of the manufactured resonant pressure sensor have been compared with that of the analytical and finite element modeling to validate the optimization procedure. The device has been manufactured using standard 250 nm CMOS technology followed by an in-house BEOL metal-layer release through wet etching.Peer ReviewedPostprint (author's final draft

Monolithic sensor integration in CMOS technologies

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Besides being mainstream for mixed-signal electronics, CMOS technology can be used to integrate micro-electromechanical system (MEMS) on a single die, taking advantage of the structures and materials available in feature sizes around 180 nm. In this article, we demonstrate that the CMOS back-end-of-line (BEOL) layers can be postprocessed and be opportunistically used to create several kinds of MEMS sensors exhibiting good or even excellent performance, such as accelerometers, pressure sensors, and magnetometers. Despite the limitations of the available mechanical and material properties in CMOS technology, due to monolithic integration, these are compensated by the significant reduction of parasitics and system size. Furthermore, this work opens the path to create monolithic integrated multisensor (and even actuator) chips, including data fusion and intelligent processing.This work was supported in part by Baolab Microsystems; in part by the Spanish Ministry of Science, Innovation and Universities (MCIN); in part by the State Research Agency (AEI); in part by the European Social Fund (ESF) under Project RTI2018-099766-B-I00; in part by MCIN/AEI/10.13039/501100011033 under Grant PID2021-123535OB-I00; and in part by ERDF, “A way of making Europe.” The associate editor coordinating the review of this article and approving it for publication was Prof. Jean-Michel Redoute.Peer ReviewedPostprint (author's final draft

Ultrasonic link ic for wireless power and data transfer deep in body

Wireless implantable medical devices have transfigured the field of biomedical engineering with the invention of adequate power supplies. Conflicting the commonly used RF and inductive methods, ultrasonic transmission of power circumvents problems associated with low inefficiencies and electromagnetic coupling offering application for a selection of data frequencies. Moreover, it prevails over the demerits of wireless power transfer through inductive coupling. In this dissertation, the candidate explored a novel ultrasonic link for wireless power and data transfer deep in the body, integrated with MEMS ultrasonic transducers, especially intended for neuro-stimulator that is to be implanted deep in a patient's body to function as, for example the pacemaker, bladder pressure sensor, implantable blood flow monitoring system, neural stimulation system, defibrillators, circulatory assist devices, etc.Master of Engineerin

Characterization of CMOS-MEMS resonant pressure sensors

IEEE Comprehensive characterization results of a CMOS-MEMS resonant pressure sensor are presented. We have extensively evaluated the key performance parameters of our device in terms of quality factor (Q) variations under variable conditions of temperature and pressure, characterized by Knudsen number (Kn). The fundamental frequency of the reported device is 104.3 kHz. Over the full-scale pressure range of 0.1 to 100 kPa and a temperature range of –10 °C to 85 °C, Q from 450 to 62.6 have been obtained. Besides, static variations of the device capacitance have been measured and analyzed with temperature to evaluate the spring softening and the pull-in effects. A nonlinearity analysis has been performed to assess the device stability. Furthermore, a statistical mismatch analysis has been carried out to determine the deviation of resonance with etching time and ascertain maximum device yield. With our in-house BEOL metal-layer release, this sensor can be monolithically embedded in the same substrate as standard CMOS integrated circuits, resulting in a significant cost and area reduction.Peer ReviewedPostprint (author's final draft

Under pressure? Don’t lose direction! Smart sensors: Development of CMOS and MEMS on the same platform

Micro Electro Mechanical Systems (MEMS) are movable structures fabricated on the surface of silicon chips by selectively depositing and etching away materials and silicon. Such movement allows the measurement of a wide range of parameters. In the recent years, the integration of MEMS devices and electronics on the same chip i.e. CMOS-MEMS integration, has allowed the improvement of sensors’ performance and fabrication costs, extending their integration in all types of devices. In the Advanced Hardware Architectures research group at the UPC, we are currently conducting research on system-on-chip CMOS-MEMS magnetic field and pressure sensors. Contrary to pressure sensors using other technologies, resonant pressure sensors allow direct coupling to digital electronics without requiring analog to digital converters (ADCs). This feature enhances their resolution and reliability by providing more immunity to noise and interference. Recently, monolithically integrated CMOS-MEMS resonant pressure sensors have been extensively used in atmospheric pressure monitoring and altitude sensing due to their low cost, small size and high reliability. Presently, the pressure sensors integrated in the smartphones and wearable devices suffer from poor sensitivity. The primary purpose of our study is to develop an optimized CMOS-MEMS resonant pressure sensor with enhanced sensitivity at atmospheric pressure which can be utilized in a vertical GPS enhancement system. Magnetic field sensors are key in the development of electronic compasses integrated in smartphones and other devices. Currently, magnetic sensors used in smartphones do not use MEMS technology but sensors that require materials incompatible with the fabrication of CMOS electronics. Our objective is to improve the performance of MEMS based electronic compasses by using Lorentz force based MEMS magnetic sensors. Such sensors, are compatible with CMOS process and could substitute actual sensors by reducing fabrication cost

Under pressure? Don’t lose direction! Smart sensors: Development of CMOS and MEMS on the same platform

Micro Electro Mechanical Systems (MEMS) are movable structures fabricated on the surface of silicon chips by selectively depositing and etching away materials and silicon. Such movement allows the measurement of a wide range of parameters. In the recent years, the integration of MEMS devices and electronics on the same chip i.e. CMOS-MEMS integration, has allowed the improvement of sensors’ performance and fabrication costs, extending their integration in all types of devices. In the Advanced Hardware Architectures research group at the UPC, we are currently conducting research on system-on-chip CMOS-MEMS magnetic field and pressure sensors. Contrary to pressure sensors using other technologies, resonant pressure sensors allow direct coupling to digital electronics without requiring analog to digital converters (ADCs). This feature enhances their resolution and reliability by providing more immunity to noise and interference. Recently, monolithically integrated CMOS-MEMS resonant pressure sensors have been extensively used in atmospheric pressure monitoring and altitude sensing due to their low cost, small size and high reliability. Presently, the pressure sensors integrated in the smartphones and wearable devices suffer from poor sensitivity. The primary purpose of our study is to develop an optimized CMOS-MEMS resonant pressure sensor with enhanced sensitivity at atmospheric pressure which can be utilized in a vertical GPS enhancement system. Magnetic field sensors are key in the development of electronic compasses integrated in smartphones and other devices. Currently, magnetic sensors used in smartphones do not use MEMS technology but sensors that require materials incompatible with the fabrication of CMOS electronics. Our objective is to improve the performance of MEMS based electronic compasses by using Lorentz force based MEMS magnetic sensors. Such sensors, are compatible with CMOS process and could substitute actual sensors by reducing fabrication cost

Under pressure? Don’t lose direction! Smart sensors: Development of CMOS and MEMS on the same platform

Micro Electro Mechanical Systems (MEMS) are movable structures fabricated on the surface of silicon chips by selectively depositing and etching away materials and silicon. Such movement allows the measurement of a wide range of parameters. In the recent years, the integration of MEMS devices and electronics on the same chip i.e. CMOS-MEMS integration, has allowed the improvement of sensors’ performance and fabrication costs, extending their integration in all types of devices. In the Advanced Hardware Architectures research group at the UPC, we are currently conducting research on system-on-chip CMOS-MEMS magnetic field and pressure sensors. Contrary to pressure sensors using other technologies, resonant pressure sensors allow direct coupling to digital electronics without requiring analog to digital converters (ADCs). This feature enhances their resolution and reliability by providing more immunity to noise and interference. Recently, monolithically integrated CMOS-MEMS resonant pressure sensors have been extensively used in atmospheric pressure monitoring and altitude sensing due to their low cost, small size and high reliability. Presently, the pressure sensors integrated in the smartphones and wearable devices suffer from poor sensitivity. The primary purpose of our study is to develop an optimized CMOS-MEMS resonant pressure sensor with enhanced sensitivity at atmospheric pressure which can be utilized in a vertical GPS enhancement system. Magnetic field sensors are key in the development of electronic compasses integrated in smartphones and other devices. Currently, magnetic sensors used in smartphones do not use MEMS technology but sensors that require materials incompatible with the fabrication of CMOS electronics. Our objective is to improve the performance of MEMS based electronic compasses by using Lorentz force based MEMS magnetic sensors. Such sensors, are compatible with CMOS process and could substitute actual sensors by reducing fabrication cost.Postprint (published version

A comprehensive high-level model for CMOS-MEMS resonators

2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a behavioral modeling technique for CMOS microelectromechanical systems (MEMS) microresonators that enables simulation of an MEMS resonator model in Analog Hardware Description Language format within a system-level circuit simulation. A 100-kHz CMOS-MEMS resonant pressure sensor has been modeled into Verilog-A code and successfully simulated within Cadence framework. Analysis has shown that simulation results of the reported model are in agreement with the device characterization results. As an application of the proposed methodology, simulation and results of the model together with an integrated monolithic low-noise amplifier is exemplified for detecting the position change of the resonator.Peer Reviewe

Optimization of parameters for CMOS MEMS resonant pressure sensors

Micro machined resonant pressure sensors have rapidly grown into a major type of MEMS products over the past two decades. This paper presents the mathematical modelling of squeeze film damping in a MEMS resonant pressure sensor by MATLAB wherein structural and performance parameters of the device i.e. quality factor, capacitance and sensitivity are optimized relative to pressure. The change in quality factor is aimed to be optimized in order to enhance the modelling of the sensor and improve the overall sensitivity of the complete architecture. The sensor mass being 0.4 µg was designed with optimum structural parameters of 140 µm x 140 µm x 8 µm having 6 x 6 perforations along the row and column of the plate respectively to yield an enhanced quality factor of 62 and reduced damping coefficient of 4.2 µN-s/m at atmospheric pressure.Postprint (author's final draft