CMOS-SOI-MEMS Transistor for Uncooled IR Imaging (original) (raw)

CMOS-SOI-MEMS Uncooled Infrared Security Sensor With Integrated Readout

IEEE Journal of the Electron Devices Society, 2016

A new generation of uncooled passive infrared (PIR) security sensors based on a suspended thermal transistor MOS (TMOS), fabricated in standard CMOS-SOI process, released by post-etching, and wafer level packaged achieving a vacuum of <4Pa, has been developed at the Technion. One of the important features of TMOS is very low power consumption (in this case, ~2-4 pWatt) due to its subthreshold operation requiring ~10nA at 0.2V, enabling wide range of battery applications. This study focuses on the analog design of monolithically integrated readout for the electronic system, formed by the PIR sensor, its front-end analog interface and the processing circuitry. The measured Signal-to-Noise Ratio of this system is 100-200, depending on the operation point, at the Black-Body temperature of 50C, while the total input referred noise is 1µVrms and the total system current consumption is no more than 20µA. The sensors and read-out are processed with the same CMOS-SOI technology.

TMOS Novel Uncooled Sensors—theory and Practice

Microwaves, …, 2008

Uncooled IR sensors have become popular recently for imaging applications thanks to low cost, advances in MEMS and micromachining, as well as high reliability, as compared to their photon detectors counterparts, which require cooling. Several implementations of uncooled infrared detectors have been studied and implemented, such as microbolometer [1-4], pyroelectric [5], thermopile [6-8] and diode [9]. More recently, significant effort is invested to achieve compatibility with standard CMOS technologies, enabling low-cost production of large arrays of IR detectors for various applications, like driver's night vision enhancement and security. State of the art of uncooled thermal imaging is based on microbolometeric sensor arrays [10]. One of the disadvantages of current bolometers is the non-standard materials and processes used in order to fabricate them and integrate them along with readout circuits. The materials used include Vanadium Oxide and amorphous silicon, which are not available as part of a standard CMOS process and therefore can only be done by post processing in a special Fab after CMOS fabrication of the readout chip. The result is increased complexity of the design and cost. The use of exotic materials for the bolometers themselves results in problems of uniformity, repeatability and stability of the material properties. Current solutions also use relatively high bias currents in the bolometers, introducing significant self heating effects and allowing only short integration times with respect to the frame time. The large readout bandwidth results in higher noise. This paper presents a novel approach, where the sensor is implemented as MOS transistor on SOI wafer, and is used as uncooled thermal detector (TMOS) [11]. The sensor is operated in subthreshold region where the current has exponential dependence on temperature with current sensitivities exceeding 4%/K. The fabrication of the sensor using standard and reliable CMOS-SOI technology combined with monolithic integration of readout circuitry and very simple postprocessing, guaranties low production cost and predicts high performance.

TMOS novel uncooled sensors — theory and practice

2008 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems, 2008

Uncooled IR sensors have become popular recently for imaging applications thanks to low cost, advances in MEMS and micromachining, as well as high reliability, as compared to their photon detectors counterparts, which require cooling. Several implementations of uncooled infrared detectors have been studied and implemented, such as microbolometer , pyroelectric [5], thermopile [6-8] and diode . More recently, significant effort is invested to achieve compatibility with standard CMOS technologies, enabling low-cost production of large arrays of IR detectors for various applications, like driver's night vision enhancement and security.

Thermoelectric infrared sensors by CMOS technology

IEEE Electron Device Letters, 2000

We report two integrated thermoelectric infrared sensors on thin silicon oxide / nitride microstructures realized by industrial CMOS IC technology, followed by one compatible single maskless anisotropic etching step. No additional material is needed to enhance infrared absorption since the passivation layer, as provided by the CMOS process, is sufficient for certain spectral bands. The responsivities are between 12 and 28 V / W.

Design of CMOS-MEMS compatible thermopile-based infrared sensor

2017

This the aim of this project is to design an infrared detector that uses thermocouples to convert the incident infrared light into electric voltage or resistance change. Design must be CMOS compatible in order to place the evaluating electronics circuitry on the same substrate. The main tasks of the student include: • Research the literature of: o State-of-the-art infrared sensors o CMOS-MEMS manufacturing technologies o Basics of numerical simulation • Create a three-dimensional model of the infrared sensor • Simulate steady-state behavior of the microscale structure

Temperature sensitivity of SOI-CMOS transistors for use in uncooled thermal sensing

Electron Devices, IEEE …, 2005

The temperature coefficient of current (TCC) of CMOS transistors implemented on silicon-on-insulator substrates is theoretically and empirically studied for its potential use in uncooled thermal sensing. Modeling and measurements show TCC values in subthreshold of more than 6%/K, better than state of the art microbolometer temperature coefficient of resistance, and less than 0.4%/K in saturation-comparable with metals. Models and measurements are shown for the TCC dependence upon operating point, temperature and channel length. A simple semi-empirical model for the TCC at subthreshold based on long channel approximation is suggested and shown to agree with measurements for channel length down to 0.35 m. The model and measurements show a logarithmic tradeoff between subthreshold current and the TCC, which is important in the design of sensors.

A CMOS-MEMS Thermopile with an Integrated Temperature Sensing Diode for Mid-IR Thermometry

In this paper, we describe an infrared thermopile sensor comprising of single crystal silicon p+ and n+ elements, with an integrated diode temperature sensor fabricated using a commercial SOI-CMOS process followed by Deep Reactive Ion Etching (DRIE). The chip area is 1.16 mm × 1.06 mm. The integrated diode, being on the same substrate, allows a more localized measurement of the cold junction temperature compared to a conventional external thermistor. The use of single crystal silicon allows good process control and reproducibility from device-to-device in terms of both Seebeck coefficient and sensor resistance. The device has a measured responsivity of 23 V/W, detectivity of 0.75 × 10 8 cm√Hz/W, a 50 % modulation depth of 60 Hz and shows enhanced responsivity in the 8 – 14 µm wavelength range, making it particularly suitable for thermometry applications.

An uncooled microbolometer infrared detector in any standard CMOS technology

1999

This paper reports a new microbolometer structure with the CMOS n-well layer as the active element. The n-well structures are suspended and thermally isolated by post-etching of fabricated and bonded CMOS chips, while the n-well regions are protected from etching by the electrochemical etch-stop technique in a TMAH solution. The characterization results of the fabricated chips show that the n-well

Optimal performance of CMOS compatible IR thermoelectric sensors

… Systems, Journal of, 2000

This paper presents a theoretical and empirical study of the optimal performance of CMOS compatible infrared thermoelectric sensors with varying pixel area and different aspect ratio of the pixels for two possible sensor structures: cantilever and bridge types. Optimal performance is analyzed analytically, using simplifying assumptions. This analysis is verified by comparing with the exact simulations as well as by comparing with measured results. The resistance of optimized sensors in the sense of minimal noise equivalent power (NEP) is shown to be independent of aspect ratio, but proportional to the third root of the pixel area. The product of the optimal NEP and the square root of the time constant is shown to be constant with varying aspect ratios, while the same applies with the time constant to the power of 3/8 for varying areas.

Micromachined thermally based CMOS microsensors

Proceedings of The IEEE, 1998

We also address sensors for the characterization of process-dependent thermal properties of CMOS materials, such as thermal conductivity, Seebeck coefficient, and heat capacity, whose knowledge is indispensable for thermal sensor design. Last, two complete, packaged microsystems-a thermoelectric air-flow sensor and a thermoelectric infrared intrusion detector-are reported as demonstrators. where he directed a research program in microsensors. As Acting President of the Alberta Microelectronic Centre, he was in charge of establishing a complementary metal-oxide-semiconductor metallization fab. From 1986 to 1988, he was a