We report several practical issues in the fabrication and high-temperature operation of micro suspended heating structures compatible with standard CMOS technology. Suspended microstructures are fabricated in a standard CMOS process and are released by post-process silicon etching. TMAH at 25wt% with 15~01% of IPA is found to greatly increase yield by reducing mechanical disturbances during etching. Electro-thermal properties of the polysilicon are investigated during high-temperature operation. Significant thermally -induced negative drift in resistance at high temperatures is found, and the impact on temperature control is discussed. Thermal isolation is found to be about SOWmW, and reliable operation is observed near 1000°C. INTRODUCTIONThis work concerns the fabrication of suspended microstructures in standard CMOS technology and micromachined post-processing. The microstructures are designed for micro-hot-plate-(MHP)-based thermal sensor applications, with operating temperatures of 500°C and higher. Within the context of this endeavor, this paper reports on two specific technical aspects of releasing and testing the suspended microstructures. (a) The microstructures are composed of layers of Si02 and SiN, with embedded polysilicon thermoresistors. This type of structure has been studied previously by substantial numbers of researchers and laboratories, [ 1-61, The release of such structures by post-process etching of the silicon substrate has been the subject of several investigations [ 1,7,8], where the mechanical behaviour of the microstructure during release is analyzed and/or controlled in some way, to avoid catastrophic failure of the device by mechanisms such as cracking of the structure, either during or after the release etch. In a similar vein, in this paper, we report on adding IPA to the TMAH etchant solution, and its impact on the cracking behaviour of the microstructures. (b) The second aspect that we consider is that of the behaviour of polysilicon thermoresistors during hightemperature operation. The polysilicon resistivity is

/npsi/ctrl?action=rtdoc&an=9077484&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=9077484&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1116/1.1463072Journal of vacuum science and technology. A. Vacuum, surfaces, and films, 20, 3, pp. 1100science and technology. A. Vacuum, surfaces, and films, 20, 3, pp. -1104science and technology. A. Vacuum, surfaces, and films, 20, 3, pp. , 2002 High-temperature gas sensor using perovskite thin films on a suspended microheater Grudin, O.; Marinescu, R.; Landsberger, L. M.; Kahrizi, M; Frolov, G.; Cheeke, D. J. N.; Chehab, S.; Post, Michael; Tunney, Jim; Du, Xiaomei; Yang, Dongfang; Segall, D.High-temperature gas sensor using perovskite thin films on a suspended microheater Suspended microstructures consisting of a thin oxide/nitride diaphragm with embedded polysilicon heaters were designed and fabricated using a standard complementary metal-oxide-semiconductor process and simple postprocessing. Thin films of gas sensitive materials based on the SrFeO 2.5ϩx nonstoichiometric perovskite family were deposited onto the diaphragms by room-temperature pulsed excimer laser deposition. Successful chemical sensor functionality was demonstrated. With applied power up to 30 mW, estimated temperatures of the gas sensor film up to 900°C were reached. When the device was exposed to volatile organic compounds ͑VOCs͒ such as acetone and methanol, a reversible ten to 100-fold increase in sensor film resistance was observed, with response times from less than1st oaf e wminutes. Sensor response sensitivity depended on applied power and on the nature of the VOC analyte. This sensor device has the potential for use in multiarray configurations such as in an electronic nose.

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In the community setting, assessing spirometry in school-aged children is often limited by the unavailability of respirology technicians at the point-of-care. We developed a new technique called the Rapid Expiratory Occlusion Method (REOM) which measures respiratory resistance during normal breathing, without specialized training. The aim was to examine the concordance between respiratory resistance measured with the REOM with that measured by oscillometry on the tremoflo. Children aged 6 to 17 years, with or without asthma, received respiratory resistance testing on the tremoflo, then on the REOM. Three to five replicates with a coefficient of variation ≤15% were obtained on each instrument; the primary outcome was the concordance between the average respiratory resistance on the REOM with that measured at 5 Hz (R5) on the tremoflo. Thirty-two children (11 girls; 21 boys) were enrolled with a mean age of 11.2 (range 6-17) years; after excluding 2 children not meeting reproducibility criteria, 9 healthy controls, 15 controlled asthmatics, and 6 poorly controlled asthmatics were included. Resistance measured on the REOM showed a strong correlation with R5 measured on the tremoflo (p<0.0001) with no significant differences on the Bland-Altman analyses. Children and their parents found the REOM easy to use and would consider for home use if recommended by their doctor. With the high concordance between resistance values measured on the REOM and that on the tremoflo combined with perceived ease of use, the REOM appears as a promising means for measuring lung function, thus supporting further testing of other psychometric properties.

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