The Royal Institution for the Advancement of Learning/mcgill University

Mems Vision International Inc.

Ecole Technologie Superieure

Paul-Vahe Cicek

Frederic Nabki

Mourad El-Gamal

Mohannad Elsayed

Dominique Lemoine

Dominic Deslandes

Alexandre Robichaud

Micro-machined acoustic and ultrasonic transducer (MAUT), particularly piezoelectric MAUT (PMAUT), performance tradeoffs have meant reasonable pixel depth resolution necessitated low quality factor (Q) transducers with power distributed over a large bandwidth yielding modest imaging ranges whilst high-Q transducers providing higher acoustic power output for longer imaging ranges exhibit extended ringing limiting pixel depth information. Accordingly, the inventors have established MAUTs supporting high-Q transducers for long-range high-resolution imaging by integrating electromechanical actuators (dampers) which can be selectively engaged to mechanically damped the MAUT. In several applications PMAUT arrays are required where all transducer elements should have almost identical resonant frequencies. However, prior art fabrication processes have tended to produce PMAUTs with large inter-chip and inter-wafer variances. Prior art methodologies to reduce inter-wafer process variations do not address intra-wafer or inter-chip process variations and accordingly the inventors have established manufacturing methodologies and design solutions to address these for the PMAUT resonant frequency.

Electromechanically damped resonator devices and methods

Micromachined microelectromechanical systems (MEMS) based resonators offer integration with other MEMS devices and electronics. Whilst piezoelectric film bulk acoustic resonators (FBAR) generally exhibit high electromechanical transduction efficiencies and low signal transmission losses they also suffer from low quality factors and limited resonance frequencies. In contrast electrostatic FBARs can yield high quality factors and resonance frequencies but suffer from increased fabrication complexity. lower electromechanical transduction efficiency and significant signal transmission loss. Accordingly, it would be beneficial to overcome these limitations by reducing fabrication complexity via a single metal electrode layer topping the resonator structure and supporting relatively low complexity/low resolution commercial MEMS fabrication processes by removing the fabrication requirement for narrow transduction gaps. Beneficially, embodiments of the invention provide MEMS circuits with electrostatic tuning and provide resonator designs combining the advantages of piezoelectric actuation and bulk-mode resonators.

Bulk mode microelectromechanical resonator devices and methods

Considerations for selecting capacitive sensors include accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, integration options with other sensors and/or electronics, and cost effectiveness. It is beneficial if such sensors are amenable to above-IC integration with associated control/readout circuitry for reduced parasitics and reduced footprint through area sharing. The inventors have established a combined Lorentz force based magnetometer and accelerometer MEMS sensor exploiting a low temperature, above-IC-compatible fabrication process operating without requiring vacuum packaging. By switching an electrical current between two perpendicular directions on the device structure a 2D in-plane magnetic field measurement can be achieved while concurrently, the device serves as a 1D accelerometer for out-of-plane acceleration, by switching the current off and by monitoring the structure's capacitive change in response to acceleration. The design can thus separate magnetic and inertial force measurements, utilizing a single compact device.

Combined magnetometer accelerometer MEMS devices and methods

Capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics are disclosed. A capacitive based sensor is disposed over a first predetermined portion of a wafer that includes at least a first ceramic element providing protection for the final capacitive based sensor and self-aligned processing during its manufacturing.

Methods and systems for humidity and pressure sensor overlay integration with electronics

Micromachined gyroscopes, such as those based upon microelectromechanical systems (MEMS) have the potential to dominate the rate-sensor market mainly due to their small size, low power and low cost. As MEMS gyroscopes are resonant devices requiring active excitation it would be beneficial to improve the resonator Q-factor reducing the electrical drive power requirements for the excitation circuitry. Further, many prior art MEMS gyroscope designs have multiple resonances arising from design and manufacturing considerations which require additional frequency tuning and control circuitry together with the excitation/sense circuitry. It would therefore be beneficial to enhance the bandwidth of the resonators to remove the requirement for such circuitry. Further, to address the relatively large dimensions of MEMS gyroscopes it would be beneficial for the MEMS gyroscopes to be fabricated directly above the CMOS electronics thereby reducing the die dimensions and lowering per die cost.

Microelectromechanical bulk acoustic wave devices and methods

It would be beneficial to integrate MEMS devices with silicon CMOS electronics, package them in controlled environments, e.g. vacuum for MEMS resonators, and provide industry standard electrical interconnections such as solder bumps. However, to do so requires through-wafer via-based electrical interconnections. However, the fragile nature of the MEMS devices, the requirement for vacuum, hermetic sealing, and the stresses placed on metallization membranes are not present in conventional CMOS packaging. Accordingly there is provided a means of reinforcing through-wafer vias for integrated MEMS-CMOS circuits by in-filling the through-wafer electrical vias with low temperature deposited ceramic materials deposited with processes compatible with post-processing of CMOS electronics. Beneficially ceramics such as silicon carbide provide enhanced mechanical strength, enhanced expansion matching, and increased thermal conductivity in comparison to silicon and solder materials. The ceramic reinforcing may be further adapted to include micro-channels for the provisioning of liquid cooling through the structures.

Low-temperature wafer level processing for MEMS devices

A method of providing microelectromechanical structures (MEMS) that are compatible with silicon CMOS electronics is provided. The method providing for processes and manufacturing sequences limiting the maximum exposure of an integrated circuit upon which the MEMS is manufactured to below 350&#xb0; C., and potentially to below 250&#xb0; C., thereby allowing direct manufacturing of the MEMS devices onto electronics, such as Si CMOS circuits. The method further providing for the provisioning of MEMS devices with multiple non-conductive structural layers such as silicon carbide separated with small lateral gaps. Such silicon carbide structures offering enhanced material properties, increased environmental and chemical resilience while also allowing novel designs to be implemented taking advantage of the non-conductive material of the structural layer. The use of silicon carbide being beneficial within the formation of MEMS elements such as motors, gears, rotors, translation drives, etc where increased hardness reduces wear of such elements during operation.

Low temperature ceramic Microelectromechanical structures

A method of providing microelectromechanical structures (MEMS) that are compatible with silicon CMOS electronics is provided. The method providing for processes and manufacturing sequences limiting the maximum exposure of an integrated circuit upon which the MEMS is manufactured to below 350&#xb0; C., and potentially to below 250&#xb0; C., thereby allowing direct manufacturing of the MEMS devices onto electronics, such as Si CMOS circuits. The method further providing for the provisioning of MEMS devices with multiple non-conductive structural layers such as silicon carbide separated with small lateral gaps. Such silicon carbide structures offering enhanced material properties, increased environmental and chemical resilience whilst also allowing novel designs to be implemented taking advantage of the non-conductive material of the structural layer. The use of silicon carbide being beneficial within the formation of MEMS elements such as motors, gears, rotors, translation drives, etc where increased hardness reduces wear of such elements during operation.

Low temperature ceramic microelectromechanical structures

Microelectromechanical systems (MEMS) are small integrated devices or systems that combine electrical and mechanical components. It would be beneficial for such MEMS devices to be integrated with silicon CMOS electronics and packaged in controlled environments and support industry standard mounting interconnections such as solder bump through the provisioning of through-wafer via-based electrical interconnections. However, the fragile nature of the MEMS devices, the requirement for vacuum, hermetic sealing, and stresses placed on metallization membranes are not present in packaging conventional CMOS electronics. Accordingly there is provided a means of reinforcing the through-wafer vias for such integrated MEMS-CMOS circuits by in filling a predetermined portion of the through-wafer electrical vias with low temperature deposited ceramic materials which are deposited at temperatures below 350&#xb0; C., and potentially to below 250&#xb0; C., thereby allowing the re-inforcing ceramic to be deposited after fabrication of the CMOS electronics.

Growing community of inventors

Montreal, Canada

Paul-Vahe Cicek