Effect of Polyimide Variation and its Curing Temperature on CMOS ...

Sensors & TransducersVolume 103, Issue 4April 2009www.sensorsportal.com ISSN 1726-5479Editor-in-Chief: pr<strong>of</strong>essor Sergey Y. Yurish, phone: +34 696067716, fax: +34 93 4011989, e-mail: editor@sensorsportal.comEditors for Western EuropeMeijer, Gerard C.M., Delft University <strong>of</strong> Technology, The Netherl<strong>and</strong>sFerrari, Vittorio, Universitá di Brescia, ItalyEditor South AmericaCosta-Felix, Rodrigo, Inmetro, BrazilEditor for Eastern EuropeSachenko, Anatoly, Ternopil State Economic University, UkraineAbdul Rahim, Ruzairi, Universiti Teknologi, MalaysiaAhmad, Mohd Noor, Nothern University <strong>of</strong> Engineering, MalaysiaAnnamalai, Karthigeyan, National Institute <strong>of</strong> Advanced Industrial Science<strong>and</strong> Technology, JapanArcega, Francisco, University <strong>of</strong> Zaragoza, SpainArguel, Philippe, CNRS, FranceAhn, Jae-Pyoung, Korea Institute <strong>of</strong> Science <strong>and</strong> Technology, KoreaArndt, Michael, Robert Bosch GmbH, GermanyAscoli, Giorgio, George Mason University, USAAtalay, Selcuk, Inonu University, TurkeyAtghiaee, Ahmad, University <strong>of</strong> Tehran, IranAugutis, Vygantas, Kaunas University <strong>of</strong> Technology, LithuaniaAvachit, Patil Lalch<strong>and</strong>, North Maharashtra University, IndiaAyesh, Aladdin, De Montfort University, UKBahreyni, Behraad, University <strong>of</strong> Manitoba, CanadaBaoxian, Ye, Zhengzhou University, ChinaBarford, Lee, Agilent Laboratories, USABarlingay, Ravindra, RF Arrays Systems, IndiaBasu, Sukumar, Jadavpur University, IndiaBeck, Stephen, University <strong>of</strong> Sheffield, UKBen Bouzid, Sihem, Institut National de Recherche Scientifique, TunisiaBenachaiba, Chellali, Universitaire de Bechar, AlgeriaBinnie, T. David, Napier University, UKBisch<strong>of</strong>f, Gerlinde, Inst. Analytical Chemistry, GermanyBodas, Dhananjay, IMTEK, GermanyBorges Carval, Nuno, Universidade de Aveiro, PortugalBousbia-Salah, Mounir, University <strong>of</strong> Annaba, AlgeriaBouvet, Marcel, CNRS – UPMC, FranceBrudzewski, Kazimierz, Warsaw University <strong>of</strong> Technology, Pol<strong>and</strong>Cai, Chenxin, Nanjing Normal University, ChinaCai, Qingyun, Hunan University, ChinaCampanella, Luigi, University La Sapienza, ItalyCarvalho, Vitor, Minho University, PortugalCecelja, Franjo, Brunel University, London, UKCerda Belmonte, Judith, Imperial College London, UKChakrabarty, Ch<strong>and</strong>an Kumar, Universiti Tenaga Nasional, MalaysiaChakravorty, Dipankar, Association for the Cultivation <strong>of</strong> Science, IndiaChanghai, Ru, Harbin Engineering University, ChinaChaudhari, Gajanan, Shri Shivaji Science College, IndiaChen, Jiming, Zhejiang University, ChinaChen, Rongshun, National Tsing Hua University, TaiwanCheng, Kuo-Sheng, National Cheng Kung University, TaiwanChiang, Jeffrey (Cheng-Ta), Industrial Technol. Research Institute, TaiwanChiriac, Horia, National Institute <strong>of</strong> Research <strong>and</strong> Development, RomaniaChowdhuri, Arijit, University <strong>of</strong> Delhi, IndiaChung, Wen-Yaw, Chung Yuan Christian University, TaiwanCorres, Jesus, Universidad Publica de Navarra, SpainCortes, Camilo A., Universidad Nacional de Colombia, ColombiaCourtois, Christian, Universite de Valenciennes, FranceCusano, Andrea, University <strong>of</strong> Sannio, ItalyD'Amico, Arnaldo, Università di Tor Vergata, ItalyDe Stefano, Luca, Institute for Microelectronics <strong>and</strong> Microsystem, ItalyDeshmukh, Kiran, Shri Shivaji Mahavidyalaya, Barshi, IndiaDickert, Franz L., Vienna University, AustriaDieguez, Angel, University <strong>of</strong> Barcelona, SpainDimitropoulos, Panos, University <strong>of</strong> Thessaly, GreeceDing, Jianning, Jiangsu Polytechnic University, ChinaDjordjevich, Alex<strong>and</strong>ar, City University <strong>of</strong> Hong Kong, Hong KongEditorial Advisory BoardEditors for North AmericaDatskos, Panos G., Oak Ridge National Laboratory, USAFabien, J. Josse, Marquette University, USAKatz, Evgeny, Clarkson University, USAEditor for AsiaOhyama, Shinji, Tokyo Institute <strong>of</strong> Technology, JapanEditor for Asia-PacificMukhopadhyay, Subhas, Massey University, New Zeal<strong>and</strong>Donato, Nicola, University <strong>of</strong> Messina, ItalyDonato, Patricio, Universidad de Mar del Plata, ArgentinaDong, Feng, Tianjin University, ChinaDrljaca, Predrag, Instersema Sensoric SA, Switzerl<strong>and</strong>Dubey, Venketesh, Bournemouth University, UKEnderle, Stefan, University <strong>of</strong> Ulm <strong>and</strong> KTB Mechatronics GmbH,GermanyErdem, Gursan K. Arzum, Ege University, TurkeyErkmen, Aydan M., Middle East Technical University, TurkeyEstelle, Patrice, Insa Rennes, FranceEstrada, Horacio, University <strong>of</strong> North Carolina, USAFaiz, Adil, INSA Lyon, FranceFericean, Sorin, Balluff GmbH, GermanyFern<strong>and</strong>es, Joana M., University <strong>of</strong> Porto, PortugalFrancioso, Luca, CNR-IMM Institute for Microelectronics <strong>and</strong>Microsystems, ItalyFrancis, Laurent, University Catholique de Louvain, BelgiumFu, Weiling, South-Western Hospital, Chongqing, ChinaGaura, Elena, Coventry University, UKGeng, Yanfeng, China University <strong>of</strong> Petroleum, ChinaGole, James, Georgia Institute <strong>of</strong> Technology, USAGong, Hao, National University <strong>of</strong> Singapore, SingaporeGonzalez de la Rosa, Juan Jose, University <strong>of</strong> Cadiz, SpainGranel, Annette, Goteborg University, SwedenGraff, Mason, The University <strong>of</strong> Texas at Arlington, USAGuan, Shan, Eastman Kodak, USAGuillet, Bruno, University <strong>of</strong> Caen, FranceGuo, Zhen, New Jersey Institute <strong>of</strong> Technology, USAGupta, Narendra Kumar, Napier University, UKHadjiloucas, Sillas, The University <strong>of</strong> Reading, UKHashsham, Syed, Michigan State University, USAHasni, Abdelhafid, Bechar University, AlgeriaHern<strong>and</strong>ez, Alvaro, University <strong>of</strong> Alcala, SpainHern<strong>and</strong>ez, Wilmar, Universidad Politecnica de Madrid, SpainHomentcovschi, Dorel, SUNY Binghamton, USAHorstman, Tom, U.S. Automation Group, LLC, USAHsiai, Tzung (John), University <strong>of</strong> Southern California, USAHuang, Jeng-Sheng, Chung Yuan Christian University, TaiwanHuang, Star, National Tsing Hua University, TaiwanHuang, Wei, PSG Design Center, USAHui, David, University <strong>of</strong> New Orleans, USAJaffrezic-Renault, Nicole, Ecole Centrale de Lyon, FranceJaime Calvo-Galleg, Jaime, Universidad de Salamanca, SpainJames, Daniel, Griffith University, AustraliaJanting, Jakob, DELTA Danish Electronics, DenmarkJiang, Liudi, University <strong>of</strong> Southampton, UKJiang, Wei, University <strong>of</strong> Virginia, USAJiao, Zheng, Shanghai University, ChinaJohn, Joachim, IMEC, BelgiumKalach, Andrew, Voronezh Institute <strong>of</strong> Ministry <strong>of</strong> Interior, RussiaKang, Moonho, Sunmoon University, Korea SouthKaniusas, Eugenijus, Vienna University <strong>of</strong> Technology, AustriaKatake, Anup, Texas A&M University, USAKausel, Wilfried, University <strong>of</strong> Music, Vienna, AustriaKavasoglu, Nese, Mugla University, TurkeyKe, Cathy, Tyndall National Institute, Irel<strong>and</strong>Khan, Asif, Aligarh Muslim University, Aligarh, IndiaKim, Min Young, Kyungpook National University, Korea South

Ko, Sang Choon, Electronics <strong>and</strong> Telecommunications Research Institute,Korea SouthKockar, Hakan, Balikesir University, TurkeyKotulska, Malgorzata, Wroclaw University <strong>of</strong> Technology, Pol<strong>and</strong>Kratz, Henrik, Uppsala University, SwedenKumar, Arun, University <strong>of</strong> South Florida, USAKumar, Subodh, National Physical Laboratory, IndiaKung, Chih-Hsien, Chang-Jung Christian University, TaiwanLacnjevac, Caslav, University <strong>of</strong> Belgrade, SerbiaLay-Ekuakille, Aime, University <strong>of</strong> Lecce, ItalyLee, Jang Myung, Pusan National University, Korea SouthLee, Jun Su, Amkor Technology, Inc. South KoreaLei, Hua, National Starch <strong>and</strong> Chemical Company, USALi, Genxi, Nanjing University, ChinaLi, Hui, Shanghai Jiaotong University, ChinaLi, Xian-Fang, Central South University, ChinaLiang, Yuanchang, University <strong>of</strong> Washington, USALiawruangrath, Saisunee, Chiang Mai University, Thail<strong>and</strong>Liew, Kim Meow, City University <strong>of</strong> Hong Kong, Hong KongLin, Hermann, National Kaohsiung University, TaiwanLin, Paul, Clevel<strong>and</strong> State University, USALinderholm, Pontus, EPFL - Microsystems Laboratory, Switzerl<strong>and</strong>Liu, Aihua, University <strong>of</strong> Oklahoma, USALiu Changgeng, Louisiana State University, USALiu, Cheng-Hsien, National Tsing Hua University, TaiwanLiu, Songqin, Southeast University, ChinaLodeiro, Carlos, Universidade NOVA de Lisboa, PortugalLorenzo, Maria Encarnacio, Universidad Autonoma de Madrid, SpainLukaszewicz, Jerzy Pawel, Nicholas Copernicus University, Pol<strong>and</strong>Ma, Zhanfang, Northeast Normal University, ChinaMajstorovic, Vidosav, University <strong>of</strong> Belgrade, SerbiaMarquez, Alfredo, Centro de Investigacion en Materiales Avanzados,MexicoMatay, Ladislav, Slovak Academy <strong>of</strong> Sciences, SlovakiaMathur, Prafull, National Physical Laboratory, IndiaMaurya, D.K., Institute <strong>of</strong> Materials Research <strong>and</strong> Engineering, SingaporeMekid, Samir, University <strong>of</strong> Manchester, UKMelnyk, Ivan, Photon Control Inc., CanadaMendes, Paulo, University <strong>of</strong> Minho, PortugalMennell, Julie, Northumbria University, UKMi, Bin, Boston Scientific Corporation, USAMinas, Graca, University <strong>of</strong> Minho, PortugalMoghavvemi, Mahmoud, University <strong>of</strong> Malaya, MalaysiaMohammadi, Mohammad-Reza, University <strong>of</strong> Cambridge, UKMolina Flores, Esteban, Benemérita Universidad Autónoma de Puebla,MexicoMoradi, Majid, University <strong>of</strong> Kerman, IranMorello, Rosario, University "Mediterranea" <strong>of</strong> Reggio Calabria, ItalyMounir, Ben Ali, University <strong>of</strong> Sousse, TunisiaMulla, Imtiaz Sirajuddin, National Chemical Laboratory, Pune, IndiaNeelamegam, Periasamy, Sastra Deemed University, IndiaNeshkova, Milka, Bulgarian Academy <strong>of</strong> Sciences, BulgariaOberhammer, Joachim, Royal Institute <strong>of</strong> Technology, SwedenOuld Lahoucine, Cherif, University <strong>of</strong> Guelma, AlgeriaPamidighanta, Sayanu, Bharat Electronics Limited (BEL), IndiaPan, Jisheng, Institute <strong>of</strong> Materials Research & Engineering, SingaporePark, Joon-Shik, Korea Electronics Technology Institute, Korea SouthPenza, Michele, ENEA C.R., ItalyPereira, Jose Miguel, Instituto Politecnico de Setebal, PortugalPetsev, Dimiter, University <strong>of</strong> New Mexico, USAPogacnik, Lea, University <strong>of</strong> Ljubljana, SloveniaPost, Michael, National Research Council, CanadaPrance, Robert, University <strong>of</strong> Sussex, UKPrasad, Ambika, Gulbarga University, IndiaPrateepasen, Asa, Kingmoungut's University <strong>of</strong> Technology, Thail<strong>and</strong>Pullini, Daniele, Centro Ricerche FIAT, ItalyPumera, Martin, National Institute for Materials Science, JapanRadhakrishnan, S. National Chemical Laboratory, Pune, IndiaRajanna, K., Indian Institute <strong>of</strong> Science, IndiaRamadan, Qasem, Institute <strong>of</strong> Microelectronics, SingaporeRao, Basuthkar, Tata Inst. <strong>of</strong> Fundamental Research, IndiaRao<strong>of</strong>, Kosai, Joseph Fourier University <strong>of</strong> Grenoble, FranceReig, C<strong>and</strong>id, University <strong>of</strong> Valencia, SpainRestivo, Maria Teresa, University <strong>of</strong> Porto, PortugalRobert, Michel, University Henri Poincare, FranceRezazadeh, Ghader, Urmia University, IranRoyo, Santiago, Universitat Politecnica de Catalunya, SpainRodriguez, Angel, Universidad Politecnica de Cataluna, SpainRothberg, Steve, Loughborough University, UKSadana, Ajit, University <strong>of</strong> Mississippi, USASadeghian Marnani, Hamed, TU Delft, The Netherl<strong>and</strong>sS<strong>and</strong>acci, Serghei, Sensor Technology Ltd., UKSapozhnikova, Ksenia, D.I.Mendeleyev Institute for Metrology, RussiaSaxena, Vibha, Bhbha Atomic Research Centre, Mumbai, IndiaSchneider, John K., Ultra-Scan Corporation, USASeif, Selemani, Alabama A & M University, USASeifter, Achim, Los Alamos National Laboratory, USASengupta, Deepak, Advance Bio-Photonics, IndiaShankar, B. Baliga, General Monitors Transnational, USAShearwood, Christopher, Nanyang Technological University, SingaporeShin, Kyuho, Samsung Advanced Institute <strong>of</strong> Technology, KoreaShmaliy, Yuriy, Kharkiv National University <strong>of</strong> Radio Electronics,UkraineSilva Girao, Pedro, Technical University <strong>of</strong> Lisbon, PortugalSingh, V. R., National Physical Laboratory, IndiaSlomovitz, Daniel, UTE, UruguaySmith, Martin, Open University, UKSoleymanpour, Ahmad, Damghan Basic Science University, IranSomani, Prakash R., Centre for Materials for Electronics Technol., IndiaSrinivas, Talabattula, Indian Institute <strong>of</strong> Science, Bangalore, IndiaSrivastava, Arvind K., Northwestern University, USAStefan-van Staden, Raluca-Ioana, University <strong>of</strong> Pretoria, South AfricaSumriddetchka, Sarun, National Electronics <strong>and</strong> Computer TechnologyCenter, Thail<strong>and</strong>Sun, Chengliang, Polytechnic University, Hong-KongSun, Dongming, Jilin University, ChinaSun, Junhua, Beijing University <strong>of</strong> Aeronautics <strong>and</strong> Astronautics, ChinaSun, Zhiqiang, Central South University, ChinaSuri, C. Raman, Institute <strong>of</strong> Microbial Technology, IndiaSysoev, Victor, Saratov State Technical University, RussiaSzewczyk, Roman, Industrial Research Institute for Automation <strong>and</strong>Measurement, Pol<strong>and</strong>Tan, Ooi Kiang, Nanyang Technological University, Singapore,Tang, Dianping, Southwest University, ChinaTang, Jaw-Luen, National Chung Cheng University, TaiwanTeker, Kasif, Frostburg State University, USAThumbavanam Pad, Kartik, Carnegie Mellon University, USATian, Gui Yun, University <strong>of</strong> Newcastle, UKTsiantos, Vassilios, Technological Educational Institute <strong>of</strong> Kaval, GreeceTsigara, Anna, National Hellenic Research Foundation, GreeceTwomey, Karen, University College Cork, Irel<strong>and</strong>Valente, Antonio, University, Vila Real, - U.T.A.D., PortugalVaseashta, Ashok, Marshall University, USAVazquez, Carmen, Carlos III University in Madrid, SpainVieira, Manuela, Instituto Superior de Engenharia de Lisboa, PortugalVigna, Benedetto, STMicroelectronics, ItalyVrba, Radimir, Brno University <strong>of</strong> Technology, Czech RepublicW<strong>and</strong>elt, Barbara, Technical University <strong>of</strong> Lodz, Pol<strong>and</strong>Wang, Jiangping, Xi'an Shiyou University, ChinaWang, Kedong, Beihang University, ChinaWang, Liang, Advanced Micro Devices, USAWang, Mi, University <strong>of</strong> Leeds, UKWang, Shinn-Fwu, Ching Yun University, TaiwanWang, Wei-Chih, University <strong>of</strong> Washington, USAWang, Wensheng, University <strong>of</strong> Pennsylvania, USAWatson, Steven, Center for NanoSpace Technologies Inc., USAWeiping, Yan, Dalian University <strong>of</strong> Technology, ChinaWells, Stephen, Southern Company Services, USAWolkenberg, Andrzej, Institute <strong>of</strong> Electron Technology, Pol<strong>and</strong>Woods, R. Clive, Louisiana State University, USAWu, DerHo, National Pingtung University <strong>of</strong> Science <strong>and</strong> Technology,TaiwanWu, Zhaoyang, Hunan University, ChinaXiu Tao, Ge, Chuzhou University, ChinaXu, Lisheng, The Chinese University <strong>of</strong> Hong Kong, Hong KongXu, Tao, University <strong>of</strong> California, Irvine, USAYang, Dongfang, National Research Council, CanadaYang, Wuqiang, The University <strong>of</strong> Manchester, UKYaping Dan, Harvard University, USAYmeti, Aurel, University <strong>of</strong> Twente, Netherl<strong>and</strong>Yong Zhao, Northeastern University, ChinaYu, Haihu, Wuhan University <strong>of</strong> Technology, ChinaYuan, Yong, Massey University, New Zeal<strong>and</strong>Yufera Garcia, Alberto, Seville University, SpainZagnoni, Michele, University <strong>of</strong> Southampton, UKZeni, Luigi, Second University <strong>of</strong> Naples, ItalyZhong, Haoxiang, Henan Normal University, ChinaZhang, Minglong, Shanghai University, ChinaZhang, Qintao, University <strong>of</strong> California at Berkeley, USAZhang, Weiping, Shanghai Jiao Tong University, ChinaZhang, Wenming, Shanghai Jiao Tong University, ChinaZhou, Zhi-Gang, Tsinghua University, ChinaZorzano, Luis, Universidad de La Rioja, SpainZourob, Mohammed, University <strong>of</strong> Cambridge, UKSensors & Transducers Journal (ISSN 1726-5479) is a peer review international journal published monthly online by International Frequency Sensor Association (IFSA).Available in electronic <strong>and</strong> on CD. Copyright © 2009 by International Frequency Sensor Association. All rights reserved.

Sensors & Transducers JournalContentsVolume 103Issue 4April 2009www.sensorsportal.com ISSN 1726-5479Research ArticlesFrontiers <strong>of</strong> Nanosensor TechnologyVinod Kumar Khanna ......................................................................................................................... 1Dual Comb Unit High-g Accelerometer Based on CMOS-MEMS TechnologyMehrdad Mottaghi, Farzan Ghalichi, Habib B. Ghavifekr................................................................... 17Modeling <strong>of</strong> Micromachined Thermopiles Powered from the Human Body for EnergyHarvesting in Wearable DevicesVladimir Leonov, Ziyang Wang, Paolo Fiorini <strong>and</strong> Chris Van Ho<strong>of</strong> .................................................... 29Design <strong>and</strong> Development <strong>of</strong> Polysilicon-based Microhotplate for Gas Sensing ApplicationMahanth Prasad, V. K. Khanna <strong>and</strong> Ram Gopal................................................................................ 44Design <strong>of</strong> a Capacitive SOI Micromachined AccelerometerWenjing Zhao, Limei Xu. .................................................................................................................... 52Characteristic Features <strong>of</strong> RF MEMS Switches <strong>and</strong> <strong>its</strong> Various ApplicationsB. Mishra, Z. C. Alex........................................................................................................................... 65Study on the <strong>Effect</strong>s <strong>of</strong> Added Mass on Mechanical Behavior <strong>of</strong> a MicrobeamMohammad Fathalilou, Ghader Rezazadeh, Yashar Alizadeh, Soheil Talebian ............................... 73Titanium Hydride Formation in Current-Biased Titanium Microbolometer <strong>and</strong>Nanobolometer DevicesS. F. Gilmartin, K. Arshak, D. Collins, B. Lane, D. Bain, S. B. Newcomb, B. McCarthy, A. Arshak. . 83Squeeze-Film Damping <strong>Effect</strong> on Dynamic Pull-in Voltage <strong>of</strong> an Electrostatically-ActuatedMicrobeamHadi Yagubizade, Mohammad Fathalilou, Ghader Rezazadeh, Soheil Talebian .............................. 96Porous Silicon Hydrogen Sensor at Room <strong>Temperature</strong>: the <strong>Effect</strong> <strong>of</strong> Surface Modification<strong>and</strong> Noble Metal ContactsJayita Kanungo, Hiranmay Saha, Sukumar Basu .............................................................................. 102Design <strong>and</strong> Analyses <strong>of</strong> Electromagnetic MicrogeneratorNibras Awaja, Dinesh Sood, Thurai Vinay. ........................................................................................ 109Dynamic Pull-in Phenomenon in the Fully Clamped Electrostatically Actuated RectangularMicroplates Considering Damping <strong>Effect</strong>sGhader Rezazadeh, Soheil Talebian, Mohammad Fathalilou............................................................ 122Finite Element Analysis <strong>of</strong> Static <strong>and</strong> Dynamic Pull-In Instability <strong>of</strong> a Fixed-Fixed MicroBeam Considering Damping <strong>Effect</strong>sMohammad Reza Ghazavi, Ghader Rezazadeh, Saber Azizi ........................................................... 132

<strong>Effect</strong> <strong>of</strong> <strong>Polyimide</strong> <strong>Variation</strong> <strong>and</strong> <strong>its</strong> <strong>Curing</strong> <strong>Temperature</strong> on CMOS Based CapacitiveHumidity Sensor <strong>and</strong> Characterization <strong>of</strong> Integrated HeaterB. N. Baliga, D. N. Tiwari,Kamaljeet Singh, Sanjay Verma,K. Nagachenchaiah ............................... 144Sputtered Silicon as a Potential Masking Material for Glass Micromachining – A FeasibilityStudyAbhay B. Joshi, Dhananjay Bodas, S. A. Gangal............................................................................... 155Thermo-Mechanical Behavior <strong>of</strong> a Bilayer Microbeam Subjected to Nonlinear ElectrostaticPressureMaliheh Pashapour, Seyed-Mehdi Pesteii, Ghader Rezazadeh, Shahriyar Kourav<strong>and</strong>.................... 161Hydrogen <strong>and</strong> Methane Response <strong>of</strong> Pd Gate MOS SensorPreeti P<strong>and</strong>ey, J. K. Srivastava, V. N. Mishra <strong>and</strong> R. Dwivedi........................................................... 171Authors are encouraged to submit article in MS Word (doc) <strong>and</strong> Acrobat (pdf) formats by e-mail: editor@sensorsportal.comPlease visit journal’s webpage with preparation instructions: http://www.sensorsportal.com/HTML/DIGEST/Submition.htmInternational Frequency Sensor Association (IFSA).

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154Sensors & TransducersISSN 1726-5479© 2009 by IFSAhttp://www.sensorsportal.com<strong>Effect</strong> <strong>of</strong> <strong>Polyimide</strong> <strong>Variation</strong> <strong>and</strong> <strong>its</strong> <strong>Curing</strong> <strong>Temperature</strong>on CMOS Based Capacitive Humidity Sensor<strong>and</strong> Characterization <strong>of</strong> Integrated Heater1 B. N. Baliga, 2 D. N. Tiwari, 2 Kamaljeet Singh, 2 Sanjay Verma,2 K. NagachenchaiahSemiconductor Laboratory (SCL),SAS Nagar, Near Ch<strong>and</strong>igarh, India-160071E-mail: baliga@isac.gov.in, tiwari@sclchd.co.in, kamaljs@sclchd.co.inReceived: 6 April 2009 /Accepted: 20 April 2009 /Published: 27 April 2009Abstract: This paper reports humidity sensor using CMOS fabrication technology integrated withmicro heater. Vertical capacitive sensor has been chosen having better nominal capacitance. Threedifferent variants <strong>of</strong> micro heaters were fabricated <strong>and</strong> compared on both TiN <strong>and</strong> Poly-phosphorousdoped silicon. The bulk-micromachining is carried out for better thermal isolation <strong>and</strong> furtherpassivation <strong>of</strong> silicon nitride over heater is carried out for longer operational life. The effects <strong>of</strong> twodifferent polyimide on the output capacitance have been shown. Also, the effect <strong>of</strong> curing temperature<strong>and</strong> ion implantation on the output capacitance has also been detailed. Copyright © 2009 IFSA.Keywords: Bulk-micromachining, Capacitive sensor, <strong>Polyimide</strong>, Micro-heater1. IntroductionHumidity sensors are widely used in application related to meteorology, agriculture <strong>and</strong> manufacturingareas. Conventional humidity sensors are expensive <strong>and</strong> bulky but MEMS based silicon humiditysensors, compatible to st<strong>and</strong>ard CMOS IC processing are relatively cheaper due to batch fabrication[1-2]. This also allows the integration <strong>of</strong> the sensor <strong>and</strong> the circuit on the same chip known as smartsensor, resulting in improved sensitivity, linearity, accuracy, <strong>and</strong> miniaturization. Depending on thesensing principle used, humidity sensors can be broadly categorized into capacitive, resistive,mechanical <strong>and</strong> oscillator types [3-7]. Capacitive based sensors are preferred due to low powerconsumption, linear output response <strong>and</strong> low temperature coefficient.144

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154Various materials such as porous ceramics, hygroscopic polymers, <strong>and</strong> electrolytes are used ashumidity sensitive materials [8-9]. <strong>Polyimide</strong> is a type <strong>of</strong> hygroscopic material having the inherentadvantages <strong>of</strong> high sensitivity, high thermal stability (> 400 0 C), high resistance to most chemicals, <strong>and</strong>most importantly compatibility with the st<strong>and</strong>ard IC fabrication technology [10]. But polyimidehumidity sensors suffered from slow response <strong>and</strong> substantial long-term drift. This can be overcomeusing micro-heater <strong>and</strong> passivation layers. Humidity sensors reported by Qiu et al [11] has largerresponse time. Lei Gu et al [12] has integrated a poly-silicon heater to improve response time. Kang<strong>and</strong> Wise reported the sensors with high speed [13] by changing the shape <strong>and</strong> dimensions <strong>of</strong> themoisture sensing film. The reported structures, available in literature, so far have not detailed the effect<strong>of</strong> curing temperature <strong>and</strong> ion-implantation on the performances <strong>of</strong> the humidity sensors. This articlereports different variants <strong>of</strong> capacitive humidity sensors, comparison between vertical <strong>and</strong> capacitivehumidity sensor along with the description <strong>of</strong> the vertical capacitive sensors integrated with titaniumnitride(TiN) micro heater using polyimide as a sensing element. The effect <strong>of</strong> curing temperature <strong>and</strong>polyimide variation on the output capacitance has been detailed. Also the effect <strong>of</strong> different variants(keeping width <strong>and</strong> spacing as variable) <strong>of</strong> me<strong>and</strong>ered micro heater made with TiN as well asphosphorous doped poly-silicon on heater resistance have been presented in this paper. The design <strong>of</strong>sensor is detailed in section II A. Section II B describes the design <strong>and</strong> analysis <strong>of</strong> micro-heater. Thefabrication aspect compatible with CMOS foundry is detailed in section III followed by the results <strong>and</strong>discussions.2. Design <strong>of</strong> Sensor <strong>and</strong> Micro-heater2.1 Design <strong>of</strong> SensorCapacitive RH sensors consist <strong>of</strong> two electrodes <strong>and</strong> a dielectric layer between them. The dielectriclayer acts as active layer <strong>and</strong> absorbs the moisture thereby changing the dielectric constant, nominalcapacitance <strong>and</strong> consequently the measured relative humidity. This absorption changes the relativedielectric constant <strong>and</strong> thus changes nominal capacitance .The sensing capacitance can be described bythe following formula:Cs=ε εA 0 s(1)dThe relative dielectric constant <strong>of</strong> the polyimide film can be described using Looyenga’s empiricalequation [12]1/ 3 1/ 3 1/ 3 3s= [ γ ( ε w −εp) εp] , (2)ε +where γ is the fractional volume <strong>of</strong> water in the film, ε p the dielectric constant <strong>of</strong> polyimide <strong>and</strong> ε w isthe dielectric constant <strong>of</strong> water given as:where T is the temperature in K.ε w = 78.54{1-4.6 х 10 -4 (T-298)+8.8 х 10 -6 (T-298) 2 }, (3)In simplified terms the dielectric constant <strong>of</strong> the polyimide can be written as0.836 /(1+0.0049)333[ 0 .0404x(78.54] 1/ − 2.71/ ) + 2.71/ 3ε =, where x= %RH/100 (4)s145

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154Typically there is a variation <strong>of</strong> around 3 % in effective permittivity as RH value increases from40 % RH to 100 % at a particular temperature. This effect is used to realize the capacitive sensor.Capacitive sensor can be realized by laying the electrodes horizontally or vertically. Verticalconfiguration can be either in stacked form or in pillar form. Horizontal capacitor structure as shown inFig. 1 (a), is the simplest as only one layer <strong>of</strong> metallization patterning is required .The verticalstructure shown in Fig. 1(b), gives better results in terms <strong>of</strong> nominal capacitance <strong>and</strong> sensitivity. Thisstructure involves two metal layers <strong>and</strong> capacitance is governed by the thickness <strong>of</strong> the polyimide <strong>and</strong>the perforation in the top electrode.Bonding PadInterdigital Electrodes<strong>Polyimide</strong>Silicon wafer(a)Upper Electrode<strong>Polyimide</strong>Lower ElectrodesBonding PadSilicon wafer(b)Upper Metal PadUpper ElectrodeLower ElectrodeLower Metal Pad<strong>Polyimide</strong> Pillars(c)Fig. 1. Types <strong>of</strong> capacitive sensors: (a) Horizontal; (b) Vertical; (c) Pillar.The pillar structure as shown in Fig. 1(c) is not very popular due to complexity in fabrication <strong>and</strong> alsorequirement <strong>of</strong> tight tolerances. In this work stacked vertical humidity sensor as shown in Fig.1 (b) has146

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154been selected. It is worth mentioning here that optimization has to be done for nominal capacitance<strong>and</strong> sensitivity for having better performance.Fig. 2. Comparison <strong>of</strong> capacitance variation on output capacitance.2.2. Micro Heater DesignMicro heater is incorporated in the humidity sensor to improve the response time. The heater elementsunderneath the sensor are fired to remove the absorbed <strong>and</strong> frozen moisture from the sensor. Majorchallenges in micro-heater are the thermal uniformity, low cost <strong>and</strong> compatibility with the st<strong>and</strong>ard ICprocess. Most popular used geometry is a simple me<strong>and</strong>ered poly-silicon micro heater resistor onSiO 2 /Si 3 N 4 [14-15]. The design incorporates by authors having TiN as the heating element on thedielectric membrane realized using KOH etching from backside. This material has been used as TiNformation is compatible to IC technology <strong>and</strong> also known to have excellent thermal uniformity <strong>and</strong>adhesion with nitride. The membrane consists <strong>of</strong> two stacked dielectric layers <strong>of</strong> SiO 2 (5000 A 0 ) <strong>and</strong>Si 3 N 4 (2500A 0 ). The thickness <strong>and</strong> deposition parameters are chosen carefully to compensate stresses<strong>of</strong> the deposited film. The back side <strong>of</strong> the micro-heater is subjected to bulk micromachining usingKOH for thermal isolation from the bulk. Keeping structure design <strong>and</strong> area <strong>of</strong> micro-heater equal, thewidth <strong>and</strong> corresponding spacing is varied to get three different variants as shown in Fig. 3.(a)W=S=40 um (b) W=S=20 um (c) W=S=10 umFig. 3. Three variants <strong>of</strong> micro heater with total length: (a) 11470 um; (b) 20390 um; (c) 41825 um.147

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154As shown in Fig. 3, three different sensors have been fabricated on the single chip. Sensor types (a),(b) <strong>and</strong> (c) has polyimide column width <strong>of</strong> 40, 20, <strong>and</strong> 10 µm respectively. The temperature sensorshave length 262 um <strong>and</strong> width <strong>of</strong> 4 µm.Heat loss is the considered due to the contribution by conduction, convection <strong>and</strong> radiation. The effect<strong>of</strong> radiation loss is minimal due to shielding by polyimide. According to the heat balance theory thetotal heat dissipated (∆T) to the substrate should be equal to the heat generated as shown [13]:( −t/ τ )∆ T = α P = P × R × (1 − e )(5)TTTTRTRCONV COND= (6)RCONV× R+ RCONDτ =R × C(7)TSIC = ρ × A×T × , (8)SIc SIwhere c si is the specific heat <strong>of</strong> silicon, α T is the thermal resistance <strong>of</strong> the heat transfer P T is the powerdissipated, ρ is the density <strong>of</strong> silicon <strong>and</strong> C SI is the lumped thermal capacitance <strong>of</strong> the silicon substrate.The relation shown in equation (7) implies that R T <strong>and</strong> C SI has to be decreased in order to obtain asmall thermal time constant ,independent <strong>of</strong> chip size. The temperature change at the surface <strong>of</strong> thechip in steady state is given as ∆T S = P T R T , which indicates that, has to be increased in order to obtainlarger increase in temperature for the same amount <strong>of</strong> power dissipation. The above criteria <strong>and</strong>equations have been used for designing the micro-heater. The heat generated as well as dissipation isimportant as more heat generation will improve the response time. However, too much heat generationcoupled with less heat dissipation may damage the micro-heater <strong>its</strong>elf.Silicon Nitride/Silicon DioxideHeating Element (Ti/TiN/Poly)Microheater2540 umAl interconnect25 um675 um1080 umAluminum (Bonding Pads)Fig. 4. Realized micro heater along with the cross section.The cross section view <strong>of</strong> the micro-heater shows the fabricated micro heater on thin membrane <strong>of</strong> 25 micronsfor better isolation.3. Fabrication <strong>of</strong> the SensorThe first step in fabrication is the formation <strong>of</strong> a 0.4 µm thin TiN (Ti deposition by sputtering followedby sintering in nitrogen) over a layer <strong>of</strong> oxide (5000 A 0 ) <strong>and</strong> nitride (2500 A 0 ). The layer was then148

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154patterned to form the integrated heater <strong>and</strong> above that another nitride layer is deposited. Similarlybackside process was carried out to deposit oxide <strong>and</strong> nitride layers. Via patterning <strong>and</strong> metaldeposition is carried out for heater contacts using reactive ion etching (RIE). After that, metalpatterning <strong>and</strong> active layer process (consisting <strong>of</strong> polyimide lithography <strong>and</strong> development) is carriedout. Boron ion implantation at 50 KeV has also been carried out on some wafers immediately afterpolyimide deposition. At the end, backside wet etching has been done. The full fabrication flow isshown in Fig. 5.(a) Oxide <strong>and</strong> nitride deposition (b) Micro-heater layer deposition (c) Micro heater pattern etching(d)Nitride deposition (e) Backside nitride deposition (f) Backside patterning(g)Via patterning & Metaldeposition(h) Metal patterning & active layerprocess(e) Backside machiningFig. 5. Process flow for the vertical stacked humidity sensor.4. Results <strong>and</strong> DiscussionsBoth horizontal <strong>and</strong> vertical structures are fabricated. The use <strong>of</strong> vertical geometry increases thecapacitance around 5 pF in the output capacitance due to increase in effective area.149

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-1544.1. Characterization <strong>of</strong> the Micro HeaterTwo widely reported methods for temperature extractions are commonly employed. [17] The firstmethod employs a calibration <strong>of</strong> the resistance versus temperature curve <strong>of</strong> the heating element in auniform temperature environment [18]. The other method explo<strong>its</strong> two different metallic resistors, aheating element <strong>and</strong> a temperature sensor, lithographically defined very close to each other, in such away that they share approximately the same temperature [19]. In this paper, former topology which issimpler is used. Equations (5)-(8) have been used for selecting the dimensions. The heaters <strong>and</strong>sensing element are realized using TiN layer. Another micro-heater using doped poly silicon (PPD)has also been fabricated <strong>and</strong> studied. The comparison <strong>of</strong> the measured results <strong>of</strong> different variants [asrepresented (a), (b), (c) in Fig. 3] is shown below in Fig. 4.Resistances values <strong>of</strong> Microheater25Element Value(k-ohms)2015105TiNPPD01 2 3VariantsFig. 6. Values <strong>of</strong> resistances for different types <strong>and</strong> material.The poly-silicon resistor has higher resistance due to <strong>its</strong> higher sheet resistivity compared to TiN. Thesensitivity is therefore better. However, most <strong>of</strong> the other parameters, such as linearity, currentcarrying capacity, etc are found to be better. The not so good linearity in poly is due to the fact that it isa semiconductor <strong>and</strong> therefore carrier concentration (n) <strong>and</strong> mobility (µ) will vary due to temperature.TiN is a metal <strong>and</strong> the temperature effect on resistivity will be determined by mobility alone.The sensors were wire bonded to a printed circuit board, <strong>and</strong> were tested inside an environmentalchamber. The chamber has the humidity range <strong>of</strong> 20-90 % <strong>and</strong> temperature ranges from -25 0 C to+55 0 C. Capacitance measurement is performed using HP4284A capacitance meter. Micro heater isfirst characterized using st<strong>and</strong>ard sensors as well as IR testing employing infrared camera (8-14 micronb<strong>and</strong>). The temperature pr<strong>of</strong>ile <strong>and</strong> power dissipation curves are shown in Fig. 7.The heater temperature depends on the dissipated power <strong>and</strong> geometry position on the membrane. Atlow temperatures, heat loss is primarily due to conduction, so a linear relationship exists. This relationcan be shown to beP = G (T-Ta), (10)where P is the power dissipation, G is the thermal loss coefficient (W/ 0 K) <strong>and</strong> Ta is the ambienttemperature. The value <strong>of</strong> G is temperature dependent <strong>and</strong> at high temperatures as convective lossesovertakes the conduction losses giving rise to, non-linearity. This can be seen in Fig. 8 which can bedivided into three sub-areas. The first part marked as A, which shows linear response, is due toconduction losses. The transition part from conduction to convection loss marked as B, which is150

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154responsible for non-linearity <strong>and</strong> can be approximated as step-wise linear. The third part, shown as C,is again linear where majority <strong>of</strong> losses are due to convection.(a)(b)Fig. 7. Micro-heater results (a) <strong>Temperature</strong> pr<strong>of</strong>ile (b) power dissipation curve.4.2. Characterization <strong>of</strong> the SensorTwo types <strong>of</strong> polyimide have been used. PI-2723 polyimide (photo-pattern able) from Dupont [24]with the thickness <strong>of</strong> 2.7 µm is used as one <strong>of</strong> them. <strong>Polyimide</strong> exhib<strong>its</strong> a thermal expansion coefficient(α P = 70 х 10 -6 0 C -1 ) which is larger than those <strong>of</strong> silicon (α si = 2.6 х 10 -6 0 C -1 ) as well as aluminum(α AL = 0.23 х 10 -6 0 C -1 ). The resulting strain can be written as∫( α ( T ) −α( T )ε th =P AL)) dT(9)This relation shows presence <strong>of</strong> strain as α P >> α AL, thereby generating tensile stress in the film. Thishas been removed by annealing at elevated temperature (≈400 0 C).<strong>Polyimide</strong>, P1 2555 (non photo pattern able) is also used to fabricate vertical capacitors sensors. Theywere developed <strong>and</strong> rinsed using DE6180 <strong>and</strong> RI -9180 solutions. The difference in outputcapacitances <strong>of</strong> 4 pF comes out using photo pattern <strong>and</strong> non-photo pattern able polyimide. Fig. 8shows the complete structure integrated with the micro-heater. As seen in the Fig. 9 the response torelative humidity is fairy linear in the range <strong>of</strong> 30-80%. In higher ranges, the surface absorption effectcreeps in which can be minimized by turning the heater on before doing any measurement on thesensors.The general expression <strong>of</strong> capacitance as a function <strong>of</strong> relative humidity has been shown by Peter et al[3] using Looyenga’s equation. This formula depends upon the topology <strong>and</strong> in our case the generalexpression can be writtenC=2.351.725⎛⎞⎜0.2873.55⎟× RH +100(11)⎝⎠[using the dielectric constant <strong>of</strong> polyimide <strong>and</strong> water as 3.0 <strong>and</strong> 80].151

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154Capacitance & voltage pr<strong>of</strong>ileCapacitance(pF)242322212019181730 40 50 60 70 80 90 100RH (%)4.543.532.521.510.50Voltage(V)Fig. 8. Complete realized structure withintegrated heater.Fig. 9. Capacitance <strong>and</strong> voltage pr<strong>of</strong>ile.4.3. <strong>Effect</strong> <strong>of</strong> <strong>Curing</strong> <strong>Temperature</strong>The effect <strong>of</strong> the curing temperature on polyimide (PI2723) has been studied. It has been observed thatthe higher curing temperature generates higher capacitance at the cost <strong>of</strong> non-linearity as shown inFig. 10. This is evident by the fact that curing makes polyimide thin due to dipolar mechanismresulting in high capacitance [21].7060Capacitance(pF)50403020200 C330 C450 C10040 50 60 70 80 90RH(%)Fig. 10. <strong>Effect</strong> <strong>of</strong> curing temperature on the output capacitance.4.4. <strong>Effect</strong> <strong>of</strong> Ion ImplantationThe effect <strong>of</strong> ion implantation in polyimide on the output capacitance has been studied. It is observedthat the sensitivity increases with the ion-implantation in the polyimide. This phenomenon validatesthe theory that maximum humidity-induced saturation concentration for all polymers found to increasewith the ion implantation.[22] As evident from the equation (2), the effective value <strong>of</strong> γ increases afterion-implantation resulting in increased capacitance as shown in Fig. 11. It is also found out that ion –implantation changes electrical conductivity, hardness <strong>and</strong> elastic modulus <strong>of</strong> polyimide. This is due todestroying <strong>of</strong> the imide structure <strong>and</strong> formation <strong>of</strong> the carbon rich, graphite-similar amorphous152

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154structure. The dose <strong>of</strong> 1e15 ions/cm 2 at 50 keV has been implanted as it is found out that highconcentration <strong>of</strong> the implant generates large non-linearity.Fig. 11. <strong>Effect</strong> <strong>of</strong> ion implantation on the output capacitance.5. ConclusionCapacitive humidity sensors have been shown with improved performances using CMOS technologycombining simple post-processing steps. Both horizontal <strong>and</strong> vertical structures are fabricated <strong>and</strong>compared. Micro heater having wide temperature range <strong>and</strong> better thermal uniformity has beenfabricated. The integrated heater has been used to increase the speed <strong>of</strong> desorption <strong>and</strong> to eliminate thevolatile impurity. The response time in our case comes out around 10s. This type <strong>of</strong> micro-heater canbe useful in variety <strong>of</strong> applications like gas sensors, micro thrusters, actuators, switches, chemicalsensors, micro fluidics devices etc. The effect <strong>of</strong> polyimide variation <strong>and</strong> the curing temperature havebeen studied. Also, the ion implantation effects on the output capacitance have been shown. To thebest <strong>of</strong> the authors’ knowledge, no simulation tool can predict the complete behavior <strong>of</strong> humiditysensor with temperature <strong>and</strong> implantation effect on sensing material. This paper shows the completedesign which is easily repeatable. The designed sensor is expected to have better reliability <strong>and</strong> can beadapted for meteorological applications.AcknowledgementsThe authors thankfully acknowledge Dr. M. M. Nayak (Deputy Director, SCL) <strong>and</strong> Dr. J. N. Roy fortheir encouragement.References[1]. C. Azereso, Leme, H. Baltes, Multi-purpose interface for sensor systems fabricated by CMOS technologywith post-processing, Sensors <strong>and</strong> Actuators A, 37-38, 1993, pp. 77-81.[2]. G. Huyberechts, M. Honore <strong>and</strong> J. Roggen, Characterization <strong>of</strong> strontium tin oxide based thick filmhumidity sensors, Sensors <strong>and</strong> Actuators B, 15-16, 1993, pp. 281-287.[3]. P J Schubert & J H Nevin, A polyimide based capacitive humidity sensor, IEEE Trans on ElectronDevices, Vol. ED 32, No. 7, July 1985, pp. 1220-1223.153

Sensors & Transducers Journal, Vol. 103, Issue 4, April 2009, pp. 144-154[4]. A. Buchhold, A. Nakladal, G. Gerlach. P. Neumann, Design studies on piezoresistive humidity sensors,Sensors Actuators B, 53, 1998, pp. 1-7.[5]. D. Dokmeci, K. Najafi, A high sensitivity polyimide capacitive humidity relative humidity sensor formonitoring anodically bonded hermetic micro packages, Journal <strong>of</strong> Micro-Electromechanical Systems, 10,2001, pp. 197-203.[6]. T. M. Berlicki, E. Murawski, M. Muszynski, S. J. Osadnik, E. L. Prociow, Thermoelement humiditysensor, Sensors Actuators A, 64, 1998, pp. 213-214.[7]. Z. M. Rittersma, Recent achievements in miniaturized humidity sensors-a review <strong>of</strong> transductiontechniques, Sensors <strong>and</strong> Actuators A, 96, 2002, pp. 196-210.[8]. T. Seiyama, N. Yamazoe, <strong>and</strong> H. Arai, Ceramic humidity sensors, Sensors <strong>and</strong> Actuators, Vol. 4, 1983,pp. 85-96.[9]. G. Harsanyi, Polymeric sensing films: New horizons in sensorics?, Sensors <strong>and</strong> Actuators, Vol. 24, 1995,pp. 85-88.[10]. T. Boltzhauser, L. Ch<strong>and</strong>ran, H. Baltes, <strong>and</strong> D. Steiner, Humidity sensing properties <strong>and</strong> electricalpermittivity <strong>of</strong> new photosensitive polyimide, Sensors <strong>and</strong> Actuators B, Vol. 5, 1991, pp 161-164.[11]. Y. Y. Qui, C. Azeredo-Leme, L. R. Alcacer, J. E. France, A CMOS humidity sensor with on-chipcalibration, Sensors <strong>and</strong> Actuators A, 92, 2001, pp. 80-87.[12]. Lei Gu, Qing-An Huang, Ming Qin, A novel capacitive-type humidity sensor using CMOS fabricationtechnology, Sensors <strong>and</strong> Actuators B, 99, 2004, pp. 491-498.[13]. Uksong Kang <strong>and</strong> Kensall D. Wise, A High-Speed Capacitive Humidity Sensor with On-Chip ThermalReset, IEEE Trans. on Electron Devices, Vol. 47, No. 4, April 2000, pp. 702-710.[14]. D. Br<strong>and</strong>, A. Krauss et al, Design <strong>and</strong> Fabrication <strong>of</strong> high-temperature micro hot-plates for drop-coated gassensors, Sensors <strong>and</strong> Actuators B, 68, 2000, pp. 223-233.[15]. C. Rossi, P. Temple-Boyer, D. Estive, Theoretical <strong>and</strong> experimental study <strong>of</strong> silicon micromachined microheater with dielectric stacked membranes, Sensors <strong>and</strong> Actuators A, 63, 1997, pp. 183-189.[16]. C. Rossi, P. Temple-Boyer, D. Estive, Realization <strong>and</strong> performance <strong>of</strong> thin SiO/SiN membrane for microheater applications, Sensors <strong>and</strong> Actuators A, 64, 1998, pp. 241-245.[17]. M. Baroncini, P. Placidi, G. C. Cardinali, A. Scorzoni, Thermal characterization <strong>of</strong> a micro heater formicro-machined gas sensors, Sensors <strong>and</strong> Actuators, A, 115, 2004, pp. 8-14.[18]. W. Chung, J. Lim, D. Lee, N. Miura, N. Yamazoe, Thermal <strong>and</strong> gas-sensing properties <strong>of</strong> planar-typemicro gas sensor, Sensors <strong>and</strong> Actuators B, 64 , 2000, pp. 118-123.[19]. A. Pike, J. W. Gardener, Thermal Modeling <strong>and</strong> characterization <strong>of</strong> micro power chemoresistive siliconsensors, Sensors <strong>and</strong> Actuators B, 45, 1997, pp. 19-26.[20]. P. R. Story, D. W. Galipeau, R. D. Mileham, A study <strong>of</strong> low-cost sensors for measuring low relativehumidity, Sensors <strong>and</strong> Actuators B, 24-25, 1995, pp. 681-685.[21]. Le Hoang Mai, Pham Thi Mai Hoa et al, Some investigation results <strong>of</strong> the instability <strong>of</strong> humidity sensorsbased on alumina <strong>and</strong> porous silicon materials, Sensors <strong>and</strong> Actuators B, 66, 2000, pp. 63-65.[22]. M. Guenthur, G. Gerlach, G. Suchaneck, K. Sahre et al, Ion-beam induced chemical <strong>and</strong> structuralmodifications in Polymers, Surface <strong>and</strong> Coatings Technology, 2002, pp 108-113.[23]. Mare Madou, Fundamentals <strong>of</strong> Micro fabrication, CRC Press.[24]. Dupont Company Pyralin, Data sheet.___________________2009 Copyright ©, International Frequency Sensor Association (IFSA). All rights reserved.(http://www.sensorsportal.com)154

Sensors & Transducers JournalGuide for ContributorsAims <strong>and</strong> ScopeSensors & Transducers Journal (ISSN 1726-5479) provides an advanced forum for the science <strong>and</strong> technology<strong>of</strong> physical, chemical sensors <strong>and</strong> biosensors. It publishes state-<strong>of</strong>-the-art reviews, regular research <strong>and</strong>application specific papers, short notes, letters to Editor <strong>and</strong> sensors related books reviews as well asacademic, practical <strong>and</strong> commercial information <strong>of</strong> interest to <strong>its</strong> readership. Because it is an open access, peerreview international journal, papers rapidly published in Sensors & Transducers Journal will receive a very highpublicity. The journal is published monthly as twelve issues per annual by International Frequency Association(IFSA). In additional, some special sponsored <strong>and</strong> conference issues published annually. Sensors &Transducers Journal is indexed <strong>and</strong> abstracted very quickly by Chemical Abstracts, IndexCopernicus JournalsMaster List, Open J-Gate, Google Scholar, etc.Topics CoveredContributions are invited on all aspects <strong>of</strong> research, development <strong>and</strong> application <strong>of</strong> the science <strong>and</strong> technology<strong>of</strong> sensors, transducers <strong>and</strong> sensor instrumentations. Topics include, but are not restricted to:• Physical, chemical <strong>and</strong> biosensors;• Digital, frequency, period, duty-cycle, time interval, PWM, pulse number output sensors <strong>and</strong> transducers;• Theory, principles, effects, design, st<strong>and</strong>ardization <strong>and</strong> modeling;• Smart sensors <strong>and</strong> systems;• Sensor instrumentation;• Virtual instruments;• Sensors interfaces, buses <strong>and</strong> networks;• Signal processing;• Frequency (period, duty-cycle)-to-digital converters, ADC;• Technologies <strong>and</strong> materials;• Nanosensors;• Microsystems;• Applications.Submission <strong>of</strong> papersArticles should be written in English. Authors are invited to submit by e-mail editor@sensorsportal.com 8-14pages article (including abstract, illustrations (color or grayscale), photos <strong>and</strong> references) in both: MS Word(doc) <strong>and</strong> Acrobat (pdf) formats. Detailed preparation instructions, paper example <strong>and</strong> template <strong>of</strong> manuscriptare available from the journal’s webpage: http://www.sensorsportal.com/HTML/DIGEST/Submition.htm Authorsmust follow the instructions strictly when submitting their manuscripts.Advertising InformationAdvertising orders <strong>and</strong> enquires may be sent to sales@sensorsportal.com Please download also our media kit:http://www.sensorsportal.com/DOWNLOADS/Media_Kit_2009.pdf