Thermal Sensors Fabricated by CMOS and Micromachining

29th European Solid-State Circuits Conference, 2003

A novel monolithic differential thermal analyzer fabricated in industrial CMOS-technology combined with post-CMOS micromachining is presented, which includes three micro-hotplates and all necessary driving and signal conditioning circuitry. Three on-chip proportional temperature controllers (one controller per micro-hotplate), regulate the micro-hotplate temperature up to 350°C with a steady-state error of less than 1% of the preset micro-hotplate temperature. A circular microhotplate design was developed to improve the hotplate power efficiency. The thermal analysis performance was assessed by melting point measurements of ammonium nitrate (melting point at 169.6°C).

18Th International Workshop on Thermal Investigation of Ics and Systems, 2012

This paper explains the design decisions and the different measurements we have done in order to characterize the thermal coupling and the characteristics of temperature sensors embedded in a integrated circuit implemented in a CMOS 65nm technology. The circuit contains a 2GHz linear power amplifier, MOS transistors behaving as heat sources and two differential temperature sensors. Temperature measurements performed with the embedded sensor are corroborated with an Infra-Red camera and a laser interferometer used as thermometer.

Surface temperature measurements were performed with a Scanning Thermal Microscope. We aim at proving an eventual sub-micrometric resolution of this metrology when using a wollaston wire probe of micrometric size. A dedicated CMOS device was designed with arrays of lines 0.35µm in size with 0.8 µm and 10µm periods. Integrated Circuits with or without a passivition layer were tested. To enhance sensitivity, the IC heat source was excited with an AC current. We show that the passivation layer spreads heat so that the lines are not distinguishable. Removing this layer allows us to distinguish the lines in the case of the 10µm period.

IEEE Journal of Solid-State Circuits, 2000

Two monolithic CMOS microsystems for gas detection and material characterization fabricated in industrial 0.8-m CMOS technology combined with post-CMOS micromachining are presented. The first microsystem comprises an array of three microhotplates, and three single-ended proportional temperature controllers (one controller per microhotplate), which regulate the microhotplate temperature up to 350 C using a polysilicon resistor as a temperature sensor on the microhotplate. The second microsystem comprises one microhotplate, and a fully differential proportional temperature controller, which regulates the microhotplate temperature up to 500 C using a platinum (Pt) resistor as a temperature sensor on the microhotplate. For gas sensing applications, the microhotplates were covered with tin dioxide (SnO 2), which changes its conductivity upon exposure to gaseous analytes. Gas tests evidenced a detection limit of 0.2 ppm for carbon monoxide (CO). For material characterization, the microhotplates were covered with ammonium nitrate (NH 4 NO 3), which exhibits a melting point of 169.6 C according to the CRC Handbook of Chemistry and Physics. The measured melting point was 168 2 C. Temperature sensors, on-and off-membrane (near the circuitry), showed excellent thermal isolation between the heated membrane area and the circuitry area on the bulk chip (overall chip temperature rose by max 3 C at 500 C microhotplate temperature).

Journal of Microelectromechanical Systems, 2017

Microelectromechanical systems sensors have been intensively developed utilizing various physical concepts, such as piezoresistive, piezoelectric, and thermoresistive effects. Among these sensing concepts, the thermoresistive effect is of interest for a wide range of thermal sensors and devices, thanks to its simplicity in implementation and high sensitivity. The effect of temperature on the electrical resistance of some metals and semiconductors has been thoroughly investigated, leading to the significant growth and successful demonstration of thermal-based sensors, such as temperature sensors, convective accelerometers and gyroscopes, and thermal flow sensors. In this paper, we review the fundamentals of the thermoresistive effect in metals and semiconductors. We also discuss the influence of design and fabrication parameters on the thermoresistive sensitivity. This paper includes several desirable features of thermoresistive sensors and recent developments in these sensors are summarized. This review provides insights into how it is affected by various parameters, and useful guidance for industrial designers in terms of high sensitivity and linearity and fast response.

Indonesian Journal of Electrical Engineering and Computer Science, 2020

This project proposed a design of low power CMOS-based thermal detector which can detect the temperature of processor such as in Central Processing Unit. By re-designing temperature detector circuit using CMOS technology, the reduction in power consumption and area size of the thermal detector can be obtained. In this paper, the design of thermal detector consists of temperature sensing core, amplifier, and Analog to Digital Converter (ADC), respectively. The sensor was designed using 0.13 µm CMOS technology and operates by sensing the temperature of processor and produced a digital output value. The temperature detection range was setup between 0 °C to 80 °C with 10 °C resolution. The temperature detector was capable to show temperature readings in binary value. It consumed an average power of 558.2 µW and a space occupancy of 0.0118 mm².

IEEE Sensors Journal, 2010

Sensors

This paper presents a novel dual-level capacitive microcantilever-based thermal detector that is implemented in the commercial surface micromachined PolyMUMPs technology. The proposed design is implemented side-by-side with four different single-level designs to enable a design-to-design performance comparison. The dual-level design exhibits a rate of capacitance change per degree Celsius that is over three times higher than that of the single-level designs and has a base capacitance that is more than twice as large. These improvements are achieved because the dual-level architecture allows a 100% electrode-to-detector area, while single-level designs are shown to suffer from an inherent trade-off between sensitivity and base capacitance. In single-level designs, either the number of the bimorph beams or the capacitance electrode can be increased for a given sensor area. The former is needed for a longer effective length of the bimorph for higher thermomechanical sensitivity (i.e., ...

International Journal on Smart Sensing and Intelligent Systems, 2009

Thermal effects in integrated piezoresistive MEMS pressure sensor may be a problem of concern in design for applications requiring high precision measurements and in continuously monitoring array of sensor network. It not only results in the shift of the offset voltage of the pressure sensor but also affects the performance of the adjacent CMOS circuit leading to erroneous values. To address this problem, the thermal effects of the integrated sensor chip along with its packaging arising out of the self heating of piezoresistors has been analyzed through a simple heat balance model which has been validated by FEM analysis and laboratory experiment. It is observed that for a typical packaged pressure sensor of 5.6mm by 5.6mm and heat transfer coefficient of 100Wm -2 K -1 , thermal effect may lead to a temperature rise of around 5 0 C whereas for a high precision application of pressure sensor even 1-2 0 C of temperature rise may lead to significant error. A methodology of co-design and a new MOS library called PTMOS for direct integration of these thermal effects of MEMS piezoresistors in the CMOS circuit has also been presented to reduce considerably the design cycle time of the integrated sensor. This integrated analysis thus helps in proper selection of the dimensions and packaging of the integrated sensor chip taking into account the thermal effects for the optimization of its space constraint and its performance with reduced design cycle time.