WO2006064029A1 - Detecteur de gaz a semiconducteur en couche mince offrant une selectivite amelioree - Google Patents

Detecteur de gaz a semiconducteur en couche mince offrant une selectivite amelioree Download PDF

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Publication number
WO2006064029A1
WO2006064029A1 PCT/EP2005/056798 EP2005056798W WO2006064029A1 WO 2006064029 A1 WO2006064029 A1 WO 2006064029A1 EP 2005056798 W EP2005056798 W EP 2005056798W WO 2006064029 A1 WO2006064029 A1 WO 2006064029A1
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WO
WIPO (PCT)
Prior art keywords
catalyst
semiconductor film
sensor
sensor device
semiconductor
Prior art date
Application number
PCT/EP2005/056798
Other languages
English (en)
Inventor
Elisabetta Comini
Nicola Poli
Giorgio Sberveglieri
Original Assignee
Consiglio Nazionale Delle Ricerche - Infm Istituto Nazionale Per La Fisica Della Materia
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Consiglio Nazionale Delle Ricerche - Infm Istituto Nazionale Per La Fisica Della Materia filed Critical Consiglio Nazionale Delle Ricerche - Infm Istituto Nazionale Per La Fisica Della Materia
Publication of WO2006064029A1 publication Critical patent/WO2006064029A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
    • G01N31/10—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using catalysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/125—Composition of the body, e.g. the composition of its sensitive layer

Definitions

  • the present invention relates to a thin film semiconductor gas sensor device of the type comprising an insulating substrate on which is deposited a film of gas-sensitive semiconductor material, and with which is associated a heating element suitable for heating the sensitive film to the operating temperature thereof.
  • This type of sensor measures the variation in the resistance of the sensitive film brought about by the chemical and/or physical absorption of the gas to be measured which is present in the ambient atmosphere; in order to detect the gases present in the environment, such sensors must generally be maintained at temperatures of above 200°C.
  • sensors which are based on measuring the variation in the work function of the sensitive film as a function of the concentration of the gas present in the atmosphere.
  • Such sensors comprise a sensitive film, the work function of which may be modified following adsorption of molecules of the gas to be detected onto the sensitive film.
  • the interest in this type of sensor primarily arises from the fact that they are capable of detecting both chemically adsorbed species and physically adsorbed species, which are weakly bound, in an operating range extending from ambient temperature to slightly higher temperatures.
  • thin film semiconductor sensors which measure the variation in the resistance of the sensitive film are widely used as gas sensors, in the light of the low production cost thereof, they generally suffer from the problem of poor selectivity for the gas to be measured, which compromises the use thereof as a single device.
  • One way of overcoming their poor selectivity is to use more than one sensor simultaneously and to post-process the acquired data by various methods.
  • EP-A-O 853 762 and EP-A-O 857 966 describe gas detectors having a porous membrane in the sensor structure which is capable of filtering the gaseous species to be monitored from other species present in the atmosphere.
  • Catalytic gas detectors as described for example in US 5 902 556, are also known. These detectors are used in continuous monitoring of atmospheres for detecting the presence of low molecular weight inflammable gases, such as for example methane, and operate by a principle which differs completely from that of the thin film sensors provided by the present invention.
  • the primary object of the present invention is to overcome the poor selectivity of thin film semiconductor gas sensors by providing a novel type of sensor which is economic to produce and particularly convenient.
  • Fig. 1 is a schematic sectional diagram of the device
  • Fig. 2 is a schematic diagram of an alternative embodiment of the sensor device according to the invention.
  • Figs. 3 and 4 are graphs showing the response of a sensor device according to the invention, described in the following exemplary embodiment, under increasing concentrations of NO 2 and, respectively, CO with the catalyst activated and not activated.
  • the sensor device comprises a thin film sensor element, of a type known per se, comprising an insulating substrate 2, a sensitive semiconductor layer 6, deposited on one face of the substrate, in electrical contact with interdigitated contacts 8 and a resistive heating element 4 applied onto the other face of the substrate 2.
  • a thin film sensor element of a type known per se, comprising an insulating substrate 2, a sensitive semiconductor layer 6, deposited on one face of the substrate, in electrical contact with interdigitated contacts 8 and a resistive heating element 4 applied onto the other face of the substrate 2.
  • a thin layer of catalyst 10 deposited on an insulating substrate 12 which bears, on the opposite face thereof relative to the catalyst, a resistive heating element 14.
  • the device according to the invention is suitable for miniaturisation to form a complete sensor system and catalyst in a single "case", in such a manner as to have a catalyst directly facing the sensitive material, which catalyst may be activated and convert a specific gaseous species, or may not be activated and so have no influence on measurement.
  • the entire device may be produced by depositing the sensitive material and the catalyst using a conventional sputtering method. It is possible to use two untreated insulating substrates, preferably of aluminium, and the sensitive layer is deposited onto one of the substrates; this substrate is then provided with the resistive heating element 4 and with the interdigitated contacts 8 which enable measurement of the resistance of the sensitive element.
  • the substrate 12 with the catalyst is provided with the heating element 14 which enables thermal activation of the catalysis process.
  • the constructive principle is not limited to specific choices for the material of the sensitive film and the catalyst.
  • the sensitive film used may comprise any semiconductor material known for this function.
  • the chemical nature of the sensitive film is naturally selected as a function of the gaseous species to be measured.
  • the catalyst is preferably selected such that it is capable of catalysing the conversion of a gaseous species likely to have an influence on the response of the sensitive film into a gaseous species which does not interfere with the response of the sensitive film to the species to be measured.
  • the distance between the two substrates, or better between the catalyst layer 10 and the semiconductor film 6 may be variable, i.e. means permitting adjustment of said distance may be provided. Typically, said distance is of the order of some hundreds of microns or less.
  • the dimensions of the substrate 12 on which the catalyst is deposited are greater than those of the substrate 2 on which the semiconductor film is deposited, in such a manner as to ensure that the catalyst is operational in the zone occupied by the sensitive film.
  • FIG. 2 The schematic diagram of Fig. 2, in which elements corresponding those in Fig. 1 are denoted by the same reference numeral, relates to the production of a device according to the invention directly onto micromachined silicon.
  • This solution uses two micromachined substrates, adhesively bonded to one another in such a manner as to maintain a fixed distance between the catalyst and the sensitive film.
  • the bottom substrate is composed of sensitive film, contacts and heating element, while the top substrate is composed of the catalyst layer and the heating element.
  • a device comprising tungsten oxide as the sensitive film, deposited on an aluminium substrate by means of magnetron sputtering, while molybdenum oxide was deposited as the catalyst material.
  • molybdenum oxide catalyses the conversion of NO 2 into NO.
  • the device was accordingly tested on nitrogen dioxide with the catalyst both activated and not activated and with a gas such as CO which ought not to be influenced by the presence of the catalyst.
  • the tungsten oxide proves to be sensitive to NO 2 , but insensitive to the gas converted into NO.
  • Fig. 3 shows the results of some tests carried out with this device, with an NO2 concentration in the ppb range, with the catalyst activated (maintained at 320°C) and not activated (maintained at ambient temperature) . It may be seen how the presence of the catalyst brings about an appreciable reduction in the response to the interfering gas.
  • Fig. 3 shows the response of the tungsten oxide sensor, maintained at a temperature of 300 0 C, towards increasing concentrations of CO (in the ppm range) with the catalyst activated (320°C) or not activated (ambient temperature) .
  • the device according to the invention thus makes it possible, by activating or deactivating the catalyst layer, to vary the sensor's response to the ambient atmosphere. This makes it possible to eliminate or reduce the influence of the interfering gas on sensor response and furthermore facilitates the identification of the gaseous species present in the atmosphere.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Molecular Biology (AREA)
  • Electrochemistry (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

Abstract

L’invention concerne un détecteur de gaz à semiconducteur en couche mince, comprenant un substrat isolant (2) pourvu d’une couche mince de matériau semiconducteur (6) et d’un élément chauffant associé (4), susceptible de porter la couche de semiconducteur à une température de fonctionnement du détecteur, ledit détecteur comprenant un deuxième substrat isolant (12) doté d’un élément chauffant respectif (14) et d’une couche catalytique (10), disposée à une certaine distance de la couche de semiconducteur (6) en regard de celle-ci, de manière à définir entre la couche catalytique (10) et la couche de semiconducteur (6) un espace pour le gaz à mesurer.
PCT/EP2005/056798 2004-12-17 2005-12-14 Detecteur de gaz a semiconducteur en couche mince offrant une selectivite amelioree WO2006064029A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO2004A000883 2004-12-17
ITTO20040883 ITTO20040883A1 (it) 2004-12-17 2004-12-17 Sensore di gas a film sottile sottile semiconduttore, con migliorata selettivita'

Publications (1)

Publication Number Publication Date
WO2006064029A1 true WO2006064029A1 (fr) 2006-06-22

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Application Number Title Priority Date Filing Date
PCT/EP2005/056798 WO2006064029A1 (fr) 2004-12-17 2005-12-14 Detecteur de gaz a semiconducteur en couche mince offrant une selectivite amelioree

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IT (1) ITTO20040883A1 (fr)
WO (1) WO2006064029A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4325213A1 (fr) * 2022-08-18 2024-02-21 Infineon Technologies AG Dispositif de détection de gaz chimio-résistif comprenant un agencement de filtre de gaz catalytique

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0517366A1 (fr) * 1991-06-07 1992-12-09 Ford Motor Company Limited Méthode et dispositif pour détecter des oxydes d'azote
EP0952447A1 (fr) * 1997-03-04 1999-10-27 Siemens Aktiengesellschaft Capteur de gaz et son utilisation de capteur de méthane et propane
WO2000047991A1 (fr) * 1999-02-10 2000-08-17 Capteur Sensors And Analysers Limited Capteurs de gaz a specificite et resistance au poison elevees
DE19916798A1 (de) * 1999-04-14 2000-11-02 Daimler Chrysler Ag Dünnschicht-Halbleiter-Gassensor und Verfahren zum Nachweis von Gasen
US6241826B1 (en) * 1998-07-06 2001-06-05 Sas Sonderabfallservice Gmbh Process for regenerating catalytic converters

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0517366A1 (fr) * 1991-06-07 1992-12-09 Ford Motor Company Limited Méthode et dispositif pour détecter des oxydes d'azote
EP0952447A1 (fr) * 1997-03-04 1999-10-27 Siemens Aktiengesellschaft Capteur de gaz et son utilisation de capteur de méthane et propane
US6241826B1 (en) * 1998-07-06 2001-06-05 Sas Sonderabfallservice Gmbh Process for regenerating catalytic converters
WO2000047991A1 (fr) * 1999-02-10 2000-08-17 Capteur Sensors And Analysers Limited Capteurs de gaz a specificite et resistance au poison elevees
DE19916798A1 (de) * 1999-04-14 2000-11-02 Daimler Chrysler Ag Dünnschicht-Halbleiter-Gassensor und Verfahren zum Nachweis von Gasen

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4325213A1 (fr) * 2022-08-18 2024-02-21 Infineon Technologies AG Dispositif de détection de gaz chimio-résistif comprenant un agencement de filtre de gaz catalytique

Also Published As

Publication number Publication date
ITTO20040883A1 (it) 2005-03-17

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