Metal Microelectromechanical Resonator Exhibiting Fast Human Activity Detection

This work presents a MEMS resonator used as an ultra-high resolution water vapor sensor (humidity sensing) to detect human activity through finger movement as a demonstrator example. This microelectromechanical resonator is designed as a clamped-clamped beam fabricated using the top metal layer of a commercial CMOS technology (0.35 μm CMOS-AMS) and monolithically integrated with conditioning and readout circuitry. Sensing is performed through the resonance frequency change due to the addition of water onto the clamped clamped beam coming from the moisture created by the evaporation of water in the human body. The sensitivity and high-speed response to the addition of water onto the metal bridge, as well as the quick dewetting of the surface, make it suitable for low-power human activity sensing

Fabrication and Measurement of a Suspended Nanochannel Microbridge Resonator Monolithically Integrated with CMOS Readout Circuitry

We present the fabrication and characterization of a suspended microbridge resonator with an embedded nanochannel. The suspended microbridge resonator is electrostatically actuated, capacitively sensed, and monolithically integrated with complementary metal-oxide-semiconductor (CMOS) readout circuitry. The device is fabricated using the back end of line (BEOL) layers of the AMS 0.35 m commercial CMOS technology, interconnecting two metal layers with a contact layer. The fabricated device has a 6 fL capacity and has one of the smallest embedded channels so far. It is able to attain a mass sensitivity of 25 ag/Hz using a fully integrable electrical transduction

Multielement Ring Array Based on Minute Size PMUTs for High Acoustic Pressure and Tunable Focus Depth

This paper presents a multielement annular ring ultrasound transducer formed by individual high-frequency PMUTs (17.5 MHz in air and 8.7 MHz in liquid) intended for high-precision axial focalization and high-performance ultrasound imaging. The prototype has five independent multielement rings fabricated by a monolithic process over CMOS, allowing for a very compact and robust design. Crosstalk between rings is under 56 dB, which guarantees an efficient beam focusing on a range between 1.4 mm and 67 µm. The presented PMUT-on-CMOS annular array with an overall diameter down to 669 µm achieves an output pressure in liquid of 4.84 kPa/V/mm 2 at 1.5 mm away from the array when the five channels are excited together, which is the largest reported for PMUTs. Pulse-echo experiments towards high-resolution imaging are demonstrated using the central ring as a receiver. With an equivalent diameter of 149 µm, this central ring provides high receiving sensitivity, 441.6 nV/Pa, higher than that of commercial hydrophones with equivalent size. A 1D ultrasound image using two channels is demonstrated, with maximum received signals of 7 mVpp when a nonintegrated amplifier is used, demonstrating the ultrasound imaging capabilities

CMOS-NEMS Copper Switches Monolithically Integrated Using a 65 nm CMOS Technology

This work demonstrates the feasibility to obtain copper nanoelectromechanical (NEMS) relays using a commercial complementary metal oxide semiconductor (CMOS) technology (ST 65 nm) following an intra CMOS-MEMS approach. We report experimental demonstration of contact-mode nano-electromechanical switches obtaining low operating voltage (5.5 V), good ION/IOFF (103) ratio, abrupt subthreshold swing (4.3 mV/decade) and minimum dimensions (3.50 µm x 100 nm x 180 nm, and gap of 100 nm). With these dimensions, the operable Cell area of the switch will be 3.5 µm (length) x 0.2 µm (100 nm width + 100 nm gap) = 0.7 µm2 which is the smallest reported one using a top-down fabrication approach

Nanomechanical switches based on metal-insulator-metal capacitors from a standard complementary-metal-oxide semiconductor technology

We report experimental demonstrations of contact-mode nano-electromechanical switches obtained using a capacitor module based on metal-insulator-metal configuration of a standard commercial complementary metal oxide semiconductor technology. The developed 2 terminals Titanium Nitride switches operate at low voltages (10 V) thanks to its small gap (27 nm), showing an excellent ION/IOFF ratio (104) and abrupt behavior (5 mV/decade, one decade of current change is achieved with a 5 mV voltage variation). A switch configuration is also presented where using two electrodes three different contact mode states can be obtained, adding functionalities to mechanical switches configurations

Disseny d'un cronòmetre i d'un freqüencímetre integrats en un NIOS controlats sobre μClinux

Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia.El projecte que es presenta permet analitzar els avantatges i inconvenients d'una programació orientada a hardware i d'una programació orientada a software a partir del desenvolupament de dos dissenys, un cronòmetre i un freqüencímetre en cadascun dels modes de programació. Donat que en les dues aplicacions es requereix alta precisió de temps (μs) i flexibilitat en el control, la solució final que es proposa és un disseny "mixt" amb dos mòduls hardware específics (cronòmetre i freqüencímetre) integrats en un NIOS/CPU sobre una FPGA. Els dos mòduls es controlen per software sobre un sistema Linux empotrat (μCLinux).El proyecto que se presenta permite analizar las ventajas e inconvenientes de una programación orientada a hardware y de una programación orientada a software a partir del desarrollo de dos diseños, un cronómetro y un frecuencímetro en cada uno de los modos de programación. Dado que en las dos aplicaciones se requiere alta precisión de tiempo (μs) y flexibilidad en el control, la solución final que se propone es un diseño "mixto" con dos módulos hardware específicos (cronómetro y frecuencímetro) integrados en un NIOS/CPU sobre una FPGA. Los dos módulos se controlan por software sobre un sistema Linux embebido (μCLinux).The project presented analyzes the advantages and disadvantages of a hardware-oriented programming and a software-oriented programming from the development of two designs, a chronometer and a frequencymeter in each of the programming modes. Because the two applications require high-precision time (μs) and control flexibility, the proposed final solution is a design "mixed" with two specific hardware modules (chronometer and frequencymeter) integrated in a NIOS/CPU on a FPGA. The two modules are controlled by software on a Linux embedded system (μClinux)

Nondestructive multlple breakdown events in very thin SI02 films

Several breakdown events and multilevel current fluctuations have been observed when ultrathin SiO2 films are subjected to constant-voltage stresses. These breakdown events are sometimes reversible, and consist in a local change of conduction mechanism. This reversibility shows that no catastrophic thermal effects occur, and that the breakdown is only a local switching between two oxide conduction states of very different conductivities

Measuring electrical current during scanning probe oxidation

Electrical current is measured during scanning probe oxidation by performing force versus distance curves under the application of a positive sample voltage. It is shown how the time dependence of the current provides information about the kinetics of oxide growth under conditions in which the tip-surface distance is known unequivocally during current acquisition. Currentmeasurements at finite tip-sample distance, in particular, unveil how the geometry of the meniscus influences its electrical conduction properties as well as the role of space charge at very small tip-sample distances

Nanometer-scale oxidation of Si(100) surfaces by tapping mode atomic force microscopy

The nanometer¿scale oxidation of Si(100) surfaces in air is performed with an atomic force microscope working in tapping mode. Applying a positive voltage to the sample with respect to the tip, two kinds of modifications are induced on the sample: grown silicon oxide mounds less than 5 nm high and mounds higher than 10 nm (which are assumed to be gold depositions). The threshold voltage necessary to produce the modification is studied as a function of the average tip¿to¿sample distance

Localized and distributed mass detectors with high sensitivity based on thin-film bulk acoustic resonators

A mass sensor based on thin-film bulk acoustic resonator, intended for biomolecular applications, is presented. The thin film is a (002) AlN membrane, sputtered over Ti/Pt on a (001) Si wafer, and released by surface micromachining of silicon. Two experiments are proposed to test the mass sensing performance of the resonators: (a) distributed loading with a MgF2 film by means of physical vapor deposition and (b) localized mass growing of a C/Pt/Ga composite using focused-ion-beam-assisted deposition, both on the top electrode. For the distributed and localized cases, the minimum detectable mass changes are 1.58×10−8g/cm2 and 7×10−15g, respectively