EP1348121A1 - Procede de fabrication de capteurs a couche mince, en particulier d'anemometres a film chaud et de capteurs d'humidite - Google Patents

Procede de fabrication de capteurs a couche mince, en particulier d'anemometres a film chaud et de capteurs d'humidite

Info

Publication number
EP1348121A1
EP1348121A1 EP01271537A EP01271537A EP1348121A1 EP 1348121 A1 EP1348121 A1 EP 1348121A1 EP 01271537 A EP01271537 A EP 01271537A EP 01271537 A EP01271537 A EP 01271537A EP 1348121 A1 EP1348121 A1 EP 1348121A1
Authority
EP
European Patent Office
Prior art keywords
glass substrate
sensor structures
composite
carrier
connection
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP01271537A
Other languages
German (de)
English (en)
Inventor
Wolfgang Timelthaler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
E&E Elektronik GmbH
Original Assignee
E&E Elektronik GmbH
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 E&E Elektronik GmbH filed Critical E&E Elektronik GmbH
Publication of EP1348121A1 publication Critical patent/EP1348121A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
    • G01F1/692—Thin-film arrangements
    • 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
    • G01N27/121—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 for determining moisture content, e.g. humidity, of the fluid

Definitions

  • the invention relates to a method for producing thin-film sensors which have a glass substrate.
  • the invention also relates to hot-film anemometers and moisture sensors which have been produced by this method. 5
  • Thin-film sensors are used in large numbers, for example in the automotive industry to measure the intake air mass flow of internal combustion engines or as moisture sensors.
  • hot film anemometers for the determination of gas mass flows are often made with a substrate made of glass. Thin, approximately 1 ⁇ m thick layers, often made of molybdenum or platinum, are applied to this glass substrate by
  • this composite is then provided with a protective layer and a contact layer.
  • the necessary sensor structures are then worked out of the applied layers, for example by a selective photo-etching process.
  • Capacitive moisture sensors are also manufactured as thin-film sensors. For this purpose, electrodes which intermesh with one another in comb-like fashion are applied to the glass substrate. A moisture-sensitive layer is placed on top, which is usually made of a polymer material.
  • the capacity of the electrode arrangement changes due to the water absorption of the moisture-sensitive layer, which is dependent on the relative air humidity.
  • the relative humidity can then be determined by measuring the capacity.
  • the hot-film anemometers are made with the thinnest possible substrate.
  • the aim is therefore to implement a hot film anometer that has a lower thermal time constant. Substrates with a small thickness reduce the thermal capacity of the substrate, thereby minimizing the disturbing heat flow between the substrate and the sensor structures that falsifies the measurement result in thermally unsteady operation.
  • substrate thickness In order to achieve sufficiently low time constants, a maximum substrate thickness of 150 ⁇ m is necessary. Substrate thicknesses of 100 ⁇ m down to about 50 ⁇ m and below should preferably be achieved.
  • the production of thin-film sensors in large numbers on such thin substrates, in particular glass substrates, is particularly difficult from a manufacturing point of view and is accompanied by high reject rates.
  • a method is known from WO98 / 34084 in which an additional membrane layer is applied to a glass support.
  • the glass carrier is then removed on a relatively small area from the back to the membrane by a selective etching process.
  • the membrane which can consist of several layers, then serves as a substrate for the sensor structures of the hot-film anemometer. In this way, thin-film sensors with a small substrate thickness can be produced.
  • These extremely low substrate thicknesses have the advantage that the response time of the hot film anemometer is minimized, but they are extremely sensitive to mechanical loads. This design has proven to be insufficiently robust, especially for use in motor vehicles.
  • EP 0043001 B1 describes a method for producing moisture sensors using thin-film technology on a glass substrate.
  • the initial thickness of the glass substrate is not further reduced after the sensor structures have been applied.
  • Even the application of an etching protection layer actively prevents the removal of glass material from the substrate in the etching process.
  • the production of thin-film sensors with thin glass substrates is therefore extremely delicate and uneconomical with this method.
  • the invention is therefore based on the object of providing a method which enables economical production of thin-film sensors on thin glass substrates in large numbers.
  • the new method means that corresponding plates with a square shape with a side length of 4 inches or round plates with a diameter of 6 inches can be used.
  • the area that can be used when applying these plate sizes for the application of the sensor structures, which have an edge length of only a few millimeters, is accordingly increased by a factor of 4 to 7. Accordingly, 4 to 7 times as many sensor structures can be applied and structured out in one work step using the new method with a reasonable reject rate. At the same time, this procedure results in a significantly reduced risk of breakage.
  • Figure 1 shows schematically the respective process steps for the production of thin-film sensors
  • Figure 2a shows a cross section through a composite
  • Figure 2b shows a cross section through a composite
  • Figure 2c shows a cross section through a composite of glass substrate and sensor structures in connection with the carrier after grinding
  • Figure 2d shows a cross section through the reclamped finished thin-film sensors.
  • FIGS. 2a to 2d are essentially intended to explain the process flow.
  • the production process is shown in FIGS. 2a to 2d using cross sections. Identical parts are identified in FIGS. 2a to 2d with identical reference symbols.
  • sensor structures 2 are first applied to a square glass substrate 1 with an initial thickness D of 0.5 mm and an edge length of 4 inches in step S10.
  • the sensor structures 2 are in this case for a hot film anemometer and therefore consist of a measuring resistor and a heating resistor and the associated protective and contact layers.
  • the sensor structures 2 can also be comb-shaped electrodes with a corresponding moisture-sensitive layer and, if appropriate, additional protective layers for moisture sensors.
  • the front side 1.1 that side of the glass substrate 1 on which the sensor structures 2 are applied is referred to as the front side 1.1.
  • the opposite side of the glass substrate 1 is consequently the back 1.2 named. Due to the comparatively large initial thickness D and the associated high mechanical stability of the glass substrate 1, its handling is unproblematic. Even after the sensor structures 2 have been applied, the comparatively thick glass substrate 1 practically never shows cracks or warps.
  • the sensor structures 2 for a hot film anemometer consist, for example, of molybdenum conductor tracks, which are applied to the glass substrate 1 by sputtering. These tracks are then covered with a protective layer, which in turn is covered with a gold contact layer. The corresponding structures are then worked out using a selective photo-etching process.
  • the glass substrate 1 in the example shown is incised in two directions perpendicular to one another between the sensor structures 2 (FIG. 2a).
  • the depth t of the trenches 1.3 thus introduced is selected so that after the grinding process of the rear side 1.2 of the glass substrate 1 described below, only the rectangular thin-film sensors remain in the glass substrate 1 without connecting bridges. In other words, the depth t of the trenches 1.3 is greater than the final thickness d of the glass substrate 1.
  • the composite of glass substrate and sensor structures is then connected to a carrier 3 on its front side in step S20.
  • a releasable clamping adhesive connection As a releasable clamping adhesive connection, a hot melt adhesive in the form of a wax 4, which is applied to the front side 1.1 of the composite of sensor structures 2 and glass substrate 1 in liquid or viscous form, is suitable, for example in accordance with the example shown.
  • the front side 1.1 is then brought into contact with the carrier 3, which preferably also consists of glass, according to FIG. 2b.
  • the wax 4 is then allowed to cool, whereby it solidifies, thus forming an immovable connection between the support 3 and the composite of sensor structures 2 and glass substrate 1.
  • hotmelt adhesives such as rosin, or synthetic material compounds, for example from the category of polymer compounds, can also be used.
  • the connection can be released again by heating to a temperature above the melting point of the adhesive.
  • Adhesive films coated with adhesive on both sides can be used as an alternative detachable mounting adhesive connection.
  • the use of these adhesive films has the advantage that the sensor structures 2 can dig into these films under the pressure of the subsequent removal processes, so that local pressure peaks in the sensors to be produced can be avoided.
  • the term adhesive films also means flat materials with the same effect, such as adhesive fabric tapes or adhesive foam films, etc.
  • foils with an adhesive coating can preferably be used, the adhesive force of which diminishes significantly or disappears under the action of UV light. In this way, the adhesive effect can be deactivated at the desired time by suitable radiation.
  • connection between the composite of glass substrate 1 and sensor structures 2 with the carrier 3 can also be produced by negative pressure.
  • air is sucked in, for example, through a perforated carrier 3.
  • the pressure on the suction side of the vacuum source drops, so that a contact pressure arises as a result of the pressure difference between the environment and the contact surface. So that the sensor structures 2 are not damaged when they are clamped onto the carrier 3, it is expedient to provide a suitable intermediate layer made of soft material.
  • the substrate material is removed in three partial steps (S31, S32, S33) from the rear side 1.2 up to the resulting final thickness d of the glass substrate 1 (FIG. 1).
  • the entire rear side 1.2 of the stretched glass substrate 1 is first processed in step S31 with a relatively coarse grinding tool.
  • the aim of step S31 is that the vast majority of the substrate material to be removed is removed here, or that after S31 the initial thickness D is scarcely greater than the resulting final thickness d of the glass substrate 1 to be aimed for.
  • the invention is not restricted to processing the entire rear side 1.2 of the glass substrate 1, but rather in this connection means a largely large-area removal of the rear side 1.2 up to the resulting final thickness d of the glass substrate 1. This means that at least 75% of the rear side 1.2 of the starting glass substrate is exposed to the removal process. Not only grinding, but also, for example, polishing or etching methods can be used as the method for carrying out the removal of substrate material.
  • the first removal step is often used to remove the majority of the volume of the substrate material to be removed, approximately 60% to 75% or more.
  • the removal process can already be completed after this step, provided that the final thickness d of the glass substrate 1 has been reached and the processed surface is of sufficient quality in terms of roughness.
  • the reverse side 1.2 is advantageously subjected to a further processing to reduce the roughness in a second step (S32) as part of the removal process. This is to reduce voltage peaks due to micro-notches on the surface.
  • the glass substrates 1 treated in this way are then mechanically relatively insensitive despite their small thickness.
  • step S32 (FIG. 1), the previously roughly ground back 1.2 is therefore subjected to a fine grinding process in the present exemplary embodiment.
  • a polishing process could also be carried out, for example.
  • Other suitable surface treatment methods can also be used. These steps can be, for example, those mentioned above, which can be carried out individually, overlaid or in any combination.
  • a further increase in the mechanical load-bearing capacity of the thin sensors is possible by means of a further removal step, in the present example according to FIG. 1, an etching process S33 on the rear side 1.2.
  • the surface of the rear side 1.2 becomes extremely smooth, which largely eliminates the notch stress peaks.
  • the back 1.2 of the glass substrate 1 is treated with hydrofluoric acid.
  • micro elevations on the rear side 1.2 are removed until the final thickness d of the glass substrate 1 is reached (FIG. 2c).
  • the glass substrates 1 treated in this way then have a very smooth back 1.2.
  • dry etching processes or polishing etching processes can also be used as etching processes.
  • the comparatively small thin-film sensors are now independently on the support after the last removal step (FIG. 2c).
  • these are then clamped onto a so-called end product carrier 5 (S40, FIG. 1).
  • the thin-film sensors on the rear sides 1.2 are connected to the end product carrier 5 by a transformer adhesive 6.
  • the front sides 1.1 of the thin-film sensors are still connected to the carrier 3 by the wax as a mounting adhesive 4 at this time.
  • the transformer glue 6 is a removable glue.
  • the transformer adhesive 6 can be deactivated with UV light, in contrast to as the adhesive 4 - in the present example, the wax.
  • clamping and transformer adhesive 4 It is fundamentally expedient that different adhesive types are used for the clamping and transformer adhesive 4, 6.
  • clamping and clamping adhesive 4, 6 are replaced by Different measures or principles of action can be deactivated (UV light, heat).
  • Clamping and reclamping adhesives 4, 6 can also be used, the effect of which wears off, for example, at different temperature levels. In this way, the desired adhesive connection can be released selectively.
  • step S50 the connection between the carrier 3 and the composite of glass substrate 1 and sensor structures 2 is released again in step S50.
  • the arrangement is heated so that the wax 4 experiences a temperature which is above its melting point.
  • the transformer adhesive 6 remains effective despite this heating.
  • the finished thin-film sensors are then only in contact with the end product carrier 5. If necessary, solder bumps can also be placed for the connection technology of the thin-film sensors.
  • the finished thin-film sensors are shipped together with the end product carrier 5.
  • the dashed arrows in FIG. 1 are intended to express that corresponding working steps can also be skipped in other configurations of the invention.
  • the example given is not intended to limit the invention to this embodiment.
  • only one removal step can be carried out in the method according to the invention, which is either one of the processes S31, S32, or S33 or comprises another removal method.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Fluid Mechanics (AREA)
  • Laminated Bodies (AREA)
  • Pressure Sensors (AREA)

Abstract

L'invention concerne un procédé économique et efficace de production de capteurs à couche mince en grande quantité, selon lequel on applique (S10) d'abord des structures de détection sur un substrat de verre et on lie (S20) de façon définitive la face avant du composite constitué du substrat de verre et des structures de détection à un support. Ensuite, on enlève (S31, S32, S33), sur une grande surface et en partant de la face arrière, le matériau constituant le substrat de verre, jusqu'à ce que celui-ci présente une épaisseur finale (d). Les étapes d'enlèvement du matériau optionnelles (S31; S33) permettent de réduire la rugosité de la face arrière. Enfin, la liaison entre le support et le composite constitué du substrat du verre et des structures de détection est défaite (S50). Etant donné que, selon ce procédé, on recouvre des substrats de verre relativement épais, le taux de rebuts résultant de casses ou de déformations des substrats de verre est nettement réduit, même lorsque les substrats de verre des capteurs à couche mince terminés sont très minces. En outre, ce procédé permet d'élever le niveau d'automatisation dans la fabrication des capteurs à couche mince.
EP01271537A 2000-12-21 2001-12-05 Procede de fabrication de capteurs a couche mince, en particulier d'anemometres a film chaud et de capteurs d'humidite Withdrawn EP1348121A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10063794A DE10063794A1 (de) 2000-12-21 2000-12-21 Verfahren zur Herstellung von Dünnschichtsensoren, insbesondere Heissfilmanemometern
DE10063794 2000-12-21
PCT/EP2001/014229 WO2002050527A1 (fr) 2000-12-21 2001-12-05 Procede de fabrication de capteurs a couche mince, en particulier d'anemometres a film chaud et de capteurs d'humidite

Publications (1)

Publication Number Publication Date
EP1348121A1 true EP1348121A1 (fr) 2003-10-01

Family

ID=7668141

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01271537A Withdrawn EP1348121A1 (fr) 2000-12-21 2001-12-05 Procede de fabrication de capteurs a couche mince, en particulier d'anemometres a film chaud et de capteurs d'humidite

Country Status (4)

Country Link
US (1) US20040113751A1 (fr)
EP (1) EP1348121A1 (fr)
DE (1) DE10063794A1 (fr)
WO (1) WO2002050527A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2958754B1 (fr) * 2010-04-12 2012-10-26 Centre Nat Rech Scient Capteur a fil chaud de taille sublimillimetrique et procede de realisation associe.
US8606486B2 (en) * 2010-06-28 2013-12-10 GM Global Technology Operations LLC System and method for measuring engine airflow

Family Cites Families (10)

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Publication number Priority date Publication date Assignee Title
DE3024297C2 (de) * 1980-06-27 1985-08-14 Endress U. Hauser Gmbh U. Co, 7867 Maulburg Kapazitiver Feuchtigkeitsfühler und Verfahren zum Herstellen seiner feuchtigkeitsempfindlichen Schicht
DE3231345C3 (de) * 1982-08-24 1994-11-17 Bosch Gmbh Robert Verfahren zur Herstellung von Sonden zur Messung der Masse und/oder Temperatur eines strömenden Mediums
US4870745A (en) * 1987-12-23 1989-10-03 Siemens-Bendix Automotive Electronics L.P. Methods of making silicon-based sensors
US5543775A (en) * 1994-03-03 1996-08-06 Mannesmann Aktiengesellschaft Thin-film measurement resistor and process for producing same
JP2624186B2 (ja) * 1994-07-29 1997-06-25 日本電気株式会社 貼り合わせシリコン基板の製造方法
JP2692659B2 (ja) * 1995-10-13 1997-12-17 日本電気株式会社 Ｓｏｉ基板および該ｓｏｉ基板の製造方法
AT2267U1 (de) * 1997-02-04 1998-07-27 E & E Elektronik Gmbh Heissfilmanemometer sowie verfahren zu seiner herstellung
EP1038315A4 (fr) * 1997-11-11 2001-07-11 Irvine Sensors Corp Procede d'amincissement de plaquettes en semi-conducteur a circuits et plaquettes ainsi produites
US20020180605A1 (en) * 1997-11-11 2002-12-05 Ozguz Volkan H. Wearable biomonitor with flexible thinned integrated circuit
DE19851055C2 (de) * 1998-11-05 2001-03-01 Fraunhofer Ges Forschung Verfahren zur Herstellung von monolithisch integrierten Sensoren

Non-Patent Citations (1)

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Title
See references of WO0250527A1 *

Also Published As

Publication number Publication date
US20040113751A1 (en) 2004-06-17
WO2002050527A1 (fr) 2002-06-27
DE10063794A1 (de) 2002-06-27

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