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Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection

A microhotplate (MHP) is a basic Microelectromechanical System (MEMS) structure that is used in many applications such as a platform for metal oxide gas sensors, microfluidics and infrared emission. Semiconductor gas sensors usually require high power because of their elevated operating temperatu...

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Main Author: Ahmed Almahi, Abdelaziz Yousif
Format: Thesis
Language:English
Published: 2009
Online Access:http://utpedia.utp.edu.my/3003/1/thesis_yousif_FINAL_PRINT.pdf
http://utpedia.utp.edu.my/3003/
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spelling my-utp-utpedia.30032017-01-25T09:44:00Z http://utpedia.utp.edu.my/3003/ Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection Ahmed Almahi, Abdelaziz Yousif A microhotplate (MHP) is a basic Microelectromechanical System (MEMS) structure that is used in many applications such as a platform for metal oxide gas sensors, microfluidics and infrared emission. Semiconductor gas sensors usually require high power because of their elevated operating temperatures. The uniformity of the temperature distribution over the sensing area is an important factor in gas detection. There are several silicon micromachined MHP that can easily withstand temperatures between 200°C and 500°C for long periods. However there is no systematic study on the effect of the thickness of the various layers of the MHP on its characteristics at high operating temperatures of up to 700oC with lower power dissipation, lower mechanical displacement and good uniformity of the temperature distribution on the MHP. The MHP for the present study consists of a 100 μm × 100 μm membrane supported by four microbridges of length 113 μm and width 20 μm designed and simulated using CoventorWare. Tetrahedron mesh with 80μm element size is applied to the solid model, while the membrane area is meshed with 5μm element size to obtain accurate FEM simulation results. In the characterization of the MHP, the length and width of the various layers (membrane, heat distributor and sensing film) are fixed while their thicknesses are varied from 0.3 μm to 3 μm to investigate the effect of thickness on the MHP characteristics. At the fixed operation temperature of 700°C, it is shown that as membrane thickness increases, power dissipation, current density, time constant and heat transfer to the silicon substrate increases, while mechanical displacement of the membrane remains constant. When the SiC heat distributor thickness increases, a small increase in power dissipation is observed while the displacement decreases. The temperature gradient on the MHP is found to decrease with increasing thickness of the SiC and is a minimum with a value of 0.005°C/μm for a thickness of 2 μm and above. An optimized MHP device at an operating temperature of 700°C was found to have a low power dissipation of about 9.25 mW, maximum mechanical displacement of 1.2 μm, a temperature gradient of 0.005°C/μm and a short time constant of 0.17 ms. 2009-07 Thesis NonPeerReviewed application/pdf en http://utpedia.utp.edu.my/3003/1/thesis_yousif_FINAL_PRINT.pdf Ahmed Almahi, Abdelaziz Yousif (2009) Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection. Masters thesis, UNIVERSITI TEKNOLOGI PETRONAS.
institution Universiti Teknologi Petronas
building UTP Resource Centre
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Petronas
content_source UTP Electronic and Digitized Intellectual Asset
url_provider http://utpedia.utp.edu.my/
language English
description A microhotplate (MHP) is a basic Microelectromechanical System (MEMS) structure that is used in many applications such as a platform for metal oxide gas sensors, microfluidics and infrared emission. Semiconductor gas sensors usually require high power because of their elevated operating temperatures. The uniformity of the temperature distribution over the sensing area is an important factor in gas detection. There are several silicon micromachined MHP that can easily withstand temperatures between 200°C and 500°C for long periods. However there is no systematic study on the effect of the thickness of the various layers of the MHP on its characteristics at high operating temperatures of up to 700oC with lower power dissipation, lower mechanical displacement and good uniformity of the temperature distribution on the MHP. The MHP for the present study consists of a 100 μm × 100 μm membrane supported by four microbridges of length 113 μm and width 20 μm designed and simulated using CoventorWare. Tetrahedron mesh with 80μm element size is applied to the solid model, while the membrane area is meshed with 5μm element size to obtain accurate FEM simulation results. In the characterization of the MHP, the length and width of the various layers (membrane, heat distributor and sensing film) are fixed while their thicknesses are varied from 0.3 μm to 3 μm to investigate the effect of thickness on the MHP characteristics. At the fixed operation temperature of 700°C, it is shown that as membrane thickness increases, power dissipation, current density, time constant and heat transfer to the silicon substrate increases, while mechanical displacement of the membrane remains constant. When the SiC heat distributor thickness increases, a small increase in power dissipation is observed while the displacement decreases. The temperature gradient on the MHP is found to decrease with increasing thickness of the SiC and is a minimum with a value of 0.005°C/μm for a thickness of 2 μm and above. An optimized MHP device at an operating temperature of 700°C was found to have a low power dissipation of about 9.25 mW, maximum mechanical displacement of 1.2 μm, a temperature gradient of 0.005°C/μm and a short time constant of 0.17 ms.
format Thesis
author Ahmed Almahi, Abdelaziz Yousif
spellingShingle Ahmed Almahi, Abdelaziz Yousif
Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection
author_facet Ahmed Almahi, Abdelaziz Yousif
author_sort Ahmed Almahi, Abdelaziz Yousif
title Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection
title_short Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection
title_full Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection
title_fullStr Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection
title_full_unstemmed Design, Simulation and Modeling of a Micromachined High Temperature Microhotplate for Application in Trace Gas Detection
title_sort design, simulation and modeling of a micromachined high temperature microhotplate for application in trace gas detection
publishDate 2009
url http://utpedia.utp.edu.my/3003/1/thesis_yousif_FINAL_PRINT.pdf
http://utpedia.utp.edu.my/3003/
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score 13.211869

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