Characterization of an Embedded Micro-Heater for Gas Sensors Applications (original) (raw)

ACCURATE EXTRACTION OF THE TEMPERATURE OF THE HEATING ELEMENT IN MICROMACHINED GAS SENSORS

The sensitivity and selectivity of micromachined gas sensors strongly depend on the temperature of the heating element; therefore an accurate determination of this temperature is required. In this paper, a simple analytical model of the thermal behavior of a heating element placed onto a thermally insulated dielectric membrane is presented. It is demonstrated that simple resistance vs. power measurements are sufficient for a precise determination of the sensor temperature. These measurements performed "once and for all" at the wafer-level on the statistically relevant number of heaters, allowed us to determine a "universal" temperature vs. power curve.

Design and manufacturing of micro heaters for gas sensors

4M 2006 - Second International Conference on Multi-Material Micro Manufacture, 2006

The paper presents the design and manufacturing steps of micro heaters, built on ceramic suspended membranes for gas sensor applications. The micro heaters are designed and fabricated by combining laser milling techniques, and conductive ceramic technology. Trenches are created in the ceramic substrate in order to define the geometry of the heater using laser processing of the substrate. The heater is completed by filling the trenches with conductive ceramic paste and then baking to remove the solvent from the paste.

Thermal simulation and optimization of micromachined gas sensor structure

2010

This work is concerned on analysing of the thermal parameters of suspended micromachined structure based on GaAs for gas detection. The main attention was dedicated to minimazin of sensor power consumption. Electro-thermal simulation confirmed the achievement of required operating temperatures (200-320°C) with the heating power less than 25 mW. Avarage temperature gradient in the active area did not exceed 0.6 K/µm.

Design and Simulation of Double-spiral Shape Micro-heater for Gas Sensing Applications

International Frequency Sensor Association Publishing, 2011

The paper presents the design and simulation of double spiral shape micro-heater using ANSYS 10.0 and MATLAB, which requires 12.5 mW-78.3 mW powers to create the temperature 181 °C-1002 °C for gas sensing applications. The results obtained from ANSYS simulation were verified using MATLAB Tool. A platinum-based bulk micro-machined hotplate of size 500 m × 500 m has been designed for fabrication as a multi-layer structure on a silicon substrate with thermal silicon dioxide as the supporting membrane, followed by LPCVD (Low pressure chemical vapor deposition) silicon nitride film. Gas sensing film (SnO 2 ) will be deposited on the interdigitated Pt electrodes formed on the PECVD oxide layer. The temperature uniformity of microhotplate (as it is essential for better sensing mechanism) based on double spiral heater has been reported in this paper. To estimate the resistance of the Pt heater, a 2000 Aº thick platinum film has been deposited by sputtering on silicon and its sheet resistance has been measured as 2.5 Ohm/□. We have used this value to calculate the resistance of Pt resistor, which was found 319 Ohm.

Design, Simulation, and Optimization of a Meander Micro Hotplate for Gas Sensors

Transactions on Electrical and Electronic Materials, 2016

Micro Hotplate (MHP) is the key component in micro-sensors, particularly gas sensors. Indeed, in metal oxide gas sensors MOX, micro-heater is used as a hotplate in order to control the temperature of the sensing layer which should be in the requisite temperature range over the heater area, so as to detect the resistive changes as a function of varying concentration of different gases. Hence, their design is a very important aspect. In this paper, we have presented the design and simulation results of a meander micro heater based on three different materials-platinum, titanium and tungsten. The dielectric membrane size is 1.4 mm × 1.6 mm with a thickness of 1.4 μm. Above the membrane, a meander heating film was deposed with a thickness of 100 nm. In order to optimize the geometry, a comparative study by simulating two different heater thicknesses, then two inter track widths has also been presented. Power consumption and temperature distribution were determined in the micro heater´s structure over a supply voltage of 5,

Ceramic Micro Heater Technology for Gas Sensors

2006 International Semiconductor Conference, 2006

The paper presents the design and manufacturing steps of micro heaters, built on ceramic suspended membranes for gas sensor applications. The micro heaters are designed and fabricated by combining laser milling techniques, and conductive ceramic technology. Trenches are created in the ceramic substrate in order to define the geometry of the heater using laser processing of the substrate. The heater is completed by filling the trenches with conductive ceramic paste and then baking to remove the solvent from the paste. The final step involves releasing the membrane by laser milling, enabling it to be suspended on four bridges, to minimise the dissipation of the heat in the substrate. The temperature of the heater element was measured with a heat camera from FLIR 40 system comparing the case of the heater positioned on top of a released membrane and that of the non-released membrane. The simulation of the heater build on top of a released membrane was compared with the heater measurements.

Thermal model for a microhot plate used in a MEM gas sensor

2008

A thermal analytical model for a MEM gas sensor is presented and compared with an electrical circuit equivalent model. The objective is to study the temperature performance of the microhot plate configured within a MEM structure used for gas sensing. From this, it is possible to determine the magnitude of the electrical current that must be applied to the polysilicon heater on regard of its dimensions and materials used, for instance, when the sensor structure is fabricated with a MEMS technology compatible with CMOS integrated circuits fabrication. Results are presented where the response time and temperature level, as a function of applied current, can be determined. The model presented can be used as a base for designing microhot plates operating in gas sensors, where temperatures in the order of 300 • C are needed and that will be integrated monolithically with associated electronics, with constraints as minimum power dissipation.

Electro-thermal simulations and modelling of micromachined gas sensor

2001 Microelectromechanical Systems Conference (Cat. No. 01EX521)

Reliability of the membrane structure for micromachined-gas sensors is one of the main concerns in MEMS technology. The major source of this problem is the stress on the membrane. In this study, the use of SiO 2 /Si 3 N 4 /SiO 2 stacked layers with optimized dimensions was found to reduce the stress on the membrane, hence improve the reliability. We have also used electro-thermal simulations with finite element analysis (FEA) to model the structural properties of the membrane in order to reduce the stress. The appropriate selection of materials and dimensions yielded maximum active area temperature of 530°°°°C at the center of the membrane with a polysilicon as a heater element, less than 5V supply voltage, 40mW of power consumption, membrane edge temperature of 177 °°°°C and acceptable mechanical stress of 0.097GPa. Upon realizing the structure with the modeled parameters, micromachined-gas sensors could respond to many industry/environment application demands.

MEMS-based microheaters integrated gas sensors

Integrated Ferroelectrics, 2018

In the present work efforts have been made to develop microheater integrated gas sensors with low power consumption. The design and simulation of a single-cell microheater is carried out using ANSYS. Low power consumption (<35 mW) platinum micro-heater has been fabricated using bulk micromachining technique on silicon dioxide membrane (1.5 lm thin), which provided improved thermal isolation of the active area of 250 Â 250 lm 2. The micro-heater has achieved a maximum temperature of 950Catanapplieddcvoltageof2.5V.Fabricatedmircro−heaterhasbeenintegratedwithSnO2basedgassensorsfortheefficientdetectionofH2andNO2gases.Thedevelopedsensorswerefoundtoyieldthemaximumsensingresponseof950 C at an applied dc voltage of 2.5 V. Fabricated mircro-heater has been integrated with SnO 2 based gas sensors for the efficient detection of H 2 and NO 2 gases. The developed sensors were found to yield the maximum sensing response of 950Catanapplieddcvoltageof2.5V.Fabricatedmircro−heaterhasbeenintegratedwithSnO2basedgassensorsfortheefficientdetectionofH2andNO2gases.Thedevelopedsensorswerefoundtoyieldthemaximumsensingresponseof184 and $2.1 with low power consumption of 29.18 and 34.53 mW towards the detection of 1 ppm of NO 2 gas and 500 ppm of H 2 gas, respectively.