Numerical simulation of the liquid phase in SnO2 thin film deposition by sol-gel-dip-coating

Carvalho, Dayene M.; Maciel, Jorge L. B.; Ravaro, Leandro P.; Garcia, Rogério Eduardo; Ferreira, Valdemir Garcia; Scalvi, Luís Vicente de Andrade

doi:10.1007/s10971-010-2263-0

Cited by 15 publications

(7 citation statements)

References 26 publications

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“…The integration with CMOS processing is essential in order to combine the sensor with MEMS and CMOS microelectronics. Currently, the deposition of metal oxide materials is being performed using several techniques, such as chemical vapor deposition [ 18 ], sputtering [ 19 ], pulsed-laser deposition [ 20 ], the sol-gel process [ 21 ] and spray pyrolysis [ 15 ]. Thin metal-oxide layers can only act as gas sensors when heated to temperatures between 250 °C and 550 °C, which means that a micro-hotplate must accompany each sensor.…”

Section: Introductionmentioning

confidence: 99%

Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

Filipovic

Selberherr

2015

Sensors

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The integration of gas sensor components into smart phones, tablets and wrist watches will revolutionize the environmental health and safety industry by providing individuals the ability to detect harmful chemicals and pollutants in the environment using always-on hand-held or wearable devices. Metal oxide gas sensors rely on changes in their electrical conductance due to the interaction of the oxide with a surrounding gas. These sensors have been extensively studied in the hopes that they will provide full gas sensing functionality with CMOS integrability. The performance of several metal oxide materials, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3) and indium-tin-oxide (ITO), are studied for the detection of various harmful or toxic cases. Due to the need for these films to be heated to temperatures between 250 °C and 550 °C during operation in order to increase their sensing functionality, a considerable degradation of the film can result. The stress generation during thin film deposition and the thermo-mechanical stress that arises during post-deposition cooling is analyzed through simulations. A tin oxide thin film is deposited using the efficient and economical spray pyrolysis technique, which involves three steps: the atomization of the precursor solution, the transport of the aerosol droplets towards the wafer and the decomposition of the precursor at or near the substrate resulting in film growth. The details of this technique and a simulation methodology are presented. The dependence of the deposition technique on the sensor performance is also discussed.

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Section: Introductionmentioning

confidence: 99%

Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

Filipovic

Selberherr

2015

Sensors

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“…It is interesting to notice that the best resolution in the X-ray diffractograms is related to the best electrical conductivity, obtained exactly for films obtained from colloidal suspensions with pH 6. The higher cristallinity obtained for this sample may be related with the sample viscosity, since the lower pH leads to higher viscosity values, resulting in more uniform layers 22 and better defined X-ray diffractograms. On the other hand, the formation of cross-linked bonds between particles 11 during the sol phase may be contributing to the formation of larger colloidal particles, leading to larger crystallites and better definition of the X-ray diffractograms, concomitant with better electrical conductivity for the pH 6 film.…”

Section: Low Temperature Electrical Characterization Of Thin Filmsmentioning

confidence: 92%

Influence of pH of colloidal suspension on the electrical conductivity of SnO2 thin films deposited via Sol-Gel-Dip-Coating

Ravaro

Scalvi

2011

Mat. Res.

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Tin dioxide (SnO 2 ) thin films are deposited by the dip-coating technique from colloidal suspensions prepared with distinct pH through the sol-gel method. The decrease of the pH contributes to the destruction of an electrical layer adjacent to particles in solution, leading to a high degree of aggregation among these particles due to the generation of cross-linked bonds (Sn-O-Sn) between them. The aggregation affects the electrical properties of films, because the pH variation produces particle with distinct sizes in the film. Undoped samples prepared from pH 6 leads to the highest conductivity among the investigated undoped samples, in agreement with X-ray diffractograms, which indicate higher crystallinity for lower pH. Arrhenius plot evaluated from temperature dependent conductivity data leads to activation energies of the deepest level between 67 to 140 meV, for the films prepared from suspensions with pH 6 to 11. The most probable explanation for this variation in the conductivity and activation energy is related to distinct potential barriers between grains, due to distinct packing caused by cross-linked bonds formed during suspension phase. Characterization of samples lightly doped with Er 3+ confirms that acid pH leads to higher conductivity, but the highest conduction takes place at even lower pH when compared to undoped thin films.

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“…Deposition can proceed in a variety of ways, including chemical vapor deposition [35], sputtering [36], pulsed-laser deposition [37], sol-gel process [38], rheotaxial growth and vacuum oxidation [19], and spray pyrolysis [8]. Sputtering and spray pyrolysis are methods which are quite straight forward to implement within the CMOS sequence.…”

Section: Sensing Layer Depositionmentioning

confidence: 99%

Processing of integrated gas sensor devices

Filipovic

Selberherr

2015

TENCON 2015 - 2015 IEEE Region 10 Conference

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The integration of gas sensor components into wearable electronics will provide individuals the ability to detect harmful chemicals and pollutants in the environment. The key to this integration is the development of processing techniques for the fabrication of sensor components which can be incorporated into the conventional CMOS fabrication sequence. This includes the etching required for the formation of a suspended membrane on top of which the microheater and sensing layer are placed and the deposition of the metal oxide sensing layer itself. Recently, spray pyrolysis has been investigated as a possible metal oxide deposition approach which is economical, easy to implement, and provides good step coverage for trench geometries. This work investigates wet chemical etching and plasma etching techniques for the generation of a suspended membrane and the spray pyrolysis and sputtering techniques for the deposition of a tin oxide gas sensing layer.

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Numerical simulation of the liquid phase in SnO2 thin film deposition by sol-gel-dip-coating

Cited by 15 publications

References 26 publications

Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

Influence of pH of colloidal suspension on the electrical conductivity of SnO2 thin films deposited via Sol-Gel-Dip-Coating

Processing of integrated gas sensor devices

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