E. Marigó

Zero-level packaging of MEMS in standard CMOS technology

A novel technique for global packaging of MEMS devices using standard CMOS technology is presented. A MEMS polysilicon resonator is fabricated and on-chip packaged using two metal layers already available from the CMOS technology. A simple buffered HF wet etching process is performed in house to release the MEMS resonator while metal deposition is used to vacuum seal the zero-level package. Both post-processing steps are carried out on CMOS chips. The design of the metal layers is carefully done in order to avoid the degradation of the MEMS. The electrical frequency response of the resonator is used for testing the performance of the final package. Electrical measurements and physical characterization demonstrate proper performance of the MEMS resonator and package.

Packaged CMOS?MEMS free?free beam oscillator

In this paper a self-oscillator based on a polysilicon free?free beam resonator monolithically integrated and packaged in a 0.35??m complementary metal?oxide?semiconductor (CMOS) technology is presented. The oscillator is capable of providing a 350?mVPP?sinusoidal signal at 25.6?MHz, with a bias polarization voltage of 7?V. The microelectromechanical systems (MEMS) resonator is packaged using only the back-end-of-line metal layers of the CMOS technology, providing a complete low-cost CMOS?MEMS processing for on-chip frequency references.

A fully integrated programmable dual-band RF filter based on electrically and mechanically coupled CMOS-MEMS resonators

In this paper, a novel fully integrated CMOS-MEMS filter implemented on a commercial CMOS technology is presented. The combination of mechanical and electrical coupling is used to enhance the response of the band pass filter. In particular, a 20 dB shape factor as low as 2 and a 35 dB stopband rejection are achieved. Moreover, the topology of the device allows obtaining a dual-bandpass filter behavior, presenting a tunable bandwidth and a deep notch between bands. Results show a dual-band filter with a 22 dB inner stopband rejection, center frequencies at 27.5 and 27.8 MHz, respectively, and a 0.6% relative bandwidth.

Dual-clock with single and monolithical 0-level vacuum packaged MEMS-on-CMOS resonator

This paper demonstrates the feasibility of a novel fabrication approach of MEMS resonators above standard CMOS circuitry and with zero-level vacuum package. As a proof of concept a monolithical CMOS-MEMS-closed loop oscillator showing dual-clock capabilities (11.9 MHz and 24.5 MHz) is presented. These two frequencies correspond to two different resonator modes, specifically the torsional and vertical out of plane, of a paddle shaped MEMS resonator.

A CMOS-MEMS filter using a V-coupler and electrical phase inversion

In this paper a fully integrated CMOS-MEMS filter is presented. The filter is formed by two beams using a V-shaped coupler which allows the in-plane vibrations. The device presents a BW of 1.85MHz for a 29MHz center frequency. The electrical phase inversion mechanism is used in order to obtain the filter response. The device is fabricated using the capacitance module present in the commercial CMOS technology from Austria Micro-systems 0.35 µm.

High Q CMOS-MEMS resonators and its applications as RF tunable band-pass filters

Clamped-clamped beam resonators are designed and fabricated in a 0.35µm CMOS commercial technology, using a simple one-step mask-less wet etching to release the MEMS structures. The resonator, with a 22MHz resonance frequency shows a Q value of 227 and 4400, when measured at atmospheric pressure and vacuum, respectively. This resonator is used as the main building block for filtering application. Using parallel filtering and differential on-chip CMOS amplification, the RF-CMOS-MEMS system forms a tunable band-pass filter with programmable bandwidth (from 100kHz to 200kHz), stop band rejections of 30 dB and shape factors at −20dB smaller than 3, providing comparable performance than other MEMS filters using specific technologies.

Linear operation of a 11MHz CMOS-MEMS resonator

In this work, the characterization of the first lateral in-plane flexural mode DETF (Double Ended Tuning Fork) MEMS resonator integrated monolithically in a CMOS 0.35µm technology is done. This characterization is done with the same resonator stand-alone and with an integrated CMOS amplifier to obtain the handling dynamic range of the applied voltage (dc bias and ac signal) for a linear behavior of the resonator.

Characterization of CMOS-MEMS resonator by pulsed mode electrostatic actuation

Experimental results of a pulsed mode electrostatic excitation on a Double Ended Tunning Fork (DETF) MEMS resonator at 11 MHz fabricated on a commercial standard 0.35um CMOS technology are described. Using small pulse widths of 4 ns, a ten percent power safe and a reduction of the MEMS non-linearities are achieved.

CMOS-MEMS free-free beam resonators

In this paper a 25 MHz free-free beam flexural resonator monolithically integrated in a 0.35 um CMOS technology is presented. A comparison between the frequency response and electrical characteristics between free-free beam and clamped-clamped beams shows higher qualities factor for free-free beams which will allow better oscillators for frequency references in terms of phase noise.

Above-IC 300 Mhz AIN SAW oscillator

This paper reports on the fabrication of an AlN SAW resonator above a commercial CMOS technology using the SilTerra MEMS on CMOS process platform. As a proof of concept, a sustaining amplifier, placed in the same substrate, along with the SAW, has been designed in order to amplify the signal provided by the SAW. Characterization of both the SAW alone and the oscillator has been carried out.