DE2252527A1 - Measurement of methyl compound film thickness - chopped laser beam detects variation in thickness compared to standard with no film - Google Patents

Measurement of methyl compound film thickness - chopped laser beam detects variation in thickness compared to standard with no film

Info

Publication number
DE2252527A1
DE2252527A1 DE19722252527 DE2252527A DE2252527A1 DE 2252527 A1 DE2252527 A1 DE 2252527A1 DE 19722252527 DE19722252527 DE 19722252527 DE 2252527 A DE2252527 A DE 2252527A DE 2252527 A1 DE2252527 A1 DE 2252527A1
Authority
DE
Germany
Prior art keywords
thickness
film
laser beam
laser
measurement
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.)
Pending
Application number
DE19722252527
Other languages
German (de)
Inventor
Dieter Dipl Phys Dr Rer Bosch
Walter Dipl Phys Dr Rer N Kroy
Werner Dipl Phys Dr Rer Rother
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.)
Airbus Defence and Space GmbH
Original Assignee
Messerschmitt Bolkow Blohm AG
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 Messerschmitt Bolkow Blohm AG filed Critical Messerschmitt Bolkow Blohm AG
Priority to DE19722252527 priority Critical patent/DE2252527A1/en
Publication of DE2252527A1 publication Critical patent/DE2252527A1/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
    • G01B11/0625—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection
    • G01B11/0633—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection using one or more discrete wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only

Abstract

The film thickness of methyl contng. cpds is measured by reflected I.R. He-Ne laser beam. A single beam is chopped into a reference and a measurement beam, mirrors collect a reflected beam from the surface with the film of e.g. toluene, xylene acetone, methanol. The two beams, which are now in effect pulses, are fed into a detector and an electronic logic circuit then measures the variation in intensity and indicates the thickness. This can be coupled to a control circuit to control the film thickness.

Description

Verfahren zur Schichtdickenbestimmung organischer Methylverbindungen Die Erfindung bezieht sich auf ein Verfahren zur Schichtdickenbestimmung organischer Methylverbindungen und eine Anordnung zur Durchführung des Verfahrens.Method for determining the layer thickness of organic methyl compounds The invention relates to a method for determining the thickness of organic layers Methyl compounds and an arrangement for carrying out the process.

Schichtdickenbestimmungen wurden bisher sehr häufig nach empirischen Verfahren vorgenommen. Auch ist es bekannt, die Schichtdicke von transparenten Medien mit Hilfe optischer Transmission zu bestimmen.Layer thickness determinations have so far been very often based on empirical methods Procedure made. It is also known the layer thickness of transparent media to be determined with the aid of optical transmission.

Alle bisher bekannten Verfahren weisen den Nachteil auf, daß sie nicht in der Lage sind, Werte hoher. Genauigkeit und vor allem mit so groß<'r Geschwindigkeit hervorzubringen, daß daraus ein Regelsignal zur Optimierung komplexer Vorginge abgeleitet werden kann.All previously known methods have the disadvantage that they do not are able to get values higher. Accuracy and above all with that great <'r speed to bring about that a control signal for optimizing complex processes is derived therefrom can be.

Der Erfindung liegt die Aufgabe zugrunde, ein Verwahren nebst der zugehörigen Anordnung zur Durchführung des Verfahrens zu entwickeln, womit Film- bzw. Schichtdicken organischer Methyl verbindungen, wie zum Beispiel methanol, Aceton, ToLuol, Xylol, Cumol oder Acetophenon, in einem Bereich von wenigen r bestimmt werden können.The invention is based on the object of keeping in addition to the to develop associated arrangement for carrying out the process, whereby film or layer thicknesses of organic methyl compounds, such as methanol, acetone, Toluene, xylene, cumene or acetophenone, can be determined in a range of a few r can.

Diese Aufgabe wird dadurch gelöst, daß der Infrarot-Laserstrahl, vorzugsweise eines He-Ne-Lasers, mittels einer Chopperanordnung in einen meßstrahl und in einen Referenzstrahl geteilt wird, wovon der Meßstrahl auf die Schicht und der Referenzstrahl auf einen unbeschichteten Teil des Trägers senkrecht auftreffen und die beiden reflektierten Strahlen einem Detektor mit nachgeschalteter Elektronik zur Bildung eines Differenzsignals zugeführt werden. Durch diese annahmen ist es beispielsweise möglich gemacht, die Filmdicke des Toluol-Farbgemisches auf dem Formzylinder von Druckereimaschinen kontinuierlich zf msssen und hieraus ein Regel signal zur Optimierung der Druckqualität zu gewinnen. ilierbei wird das Regelsignal mit großer Geschwindigkeit erhalten, was eine Folge des Einsatzes von Laserlicht ist, dessen hohe Strahlintensität auch bei sehr dünnen Schichten noch ein sehr gut auswertbares Signal liefert.This object is achieved in that the infrared laser beam, preferably a He-Ne laser, by means of a chopper arrangement into a measuring beam and into one The reference beam is split, of which the measuring beam on the layer and the reference beam impinge perpendicularly on an uncoated part of the carrier and the two reflected Beams a detector with downstream electronics to form a difference signal are fed. These assumptions make it possible, for example, to Continuous film thickness of the toluene color mixture on the forme cylinder of printing machines zf must and from this to obtain a control signal for optimizing the print quality. at the same time, the control signal is obtained at high speed, which is a consequence the use of laser light is, its high beam intensity even with very thin Layers still delivers a signal that can be evaluated very well.

Zur Durchführung des Verfahrens wird vorgeschlagen, daß in dem Strahlengang eines IR-Lasers eine Choppereinrichtung und ein Planspiegel angeordnet ist und den reflektierenden Strahlen ein halbdurchlässiger Spiegel, ein Detektor nebst Verstärker sowie eine Auswertelektronik zugeordnet sind.To carry out the method it is proposed that in the beam path an IR laser, a chopper device and a plane mirror is arranged and the reflecting rays a semi-transparent mirror, a detector and an amplifier and evaluation electronics are assigned.

Durch diese Ausbildung ist es moglich, die Infrarot-Absorption der betreffenden blethylverbindungen zur ISestimmunX der Film-oder Schichtdicke auszunutzen.Through this training it is possible to reduce the infrared absorption of the the methyl compounds concerned to determine the film or layer thickness.

Es hat weich in Versuchen gezeigt, daß die Methylgruppe C113 im Infrarot-Energiebereich von 2900 cm 1 ( ca. 3,4) stark angeregt wird, d. h. im Infrarotspektrum zeigen sich an dieser Stelte ausgepr.igte Absorptionslinien. Als Lichtquelle für die Absorptionsmessungen wird ein He-Ne-Laser vorgeschlagen, der eine Linie bei 3,39µ emittiert. Durch die spezielle Eigenschaft des Laserlichts (starke Bündelung bei hoher Intensität) wird damit eine sehr einfache Meßanordnung ermöglicht, welche eine für technische Zwecke genügend genaue Schichtdickenbestimmung erlaubt.It has softly shown in experiments that the methyl group C113 im Infrared energy range is strongly excited by 2900 cm 1 (approx. 3.4), d. H. show up in the infrared spectrum pronounced absorption lines at this point. As a light source for the absorption measurements a He-Ne laser is proposed which emits a line at 3.39µ. Through the special property of laser light (strong focus at high intensity) so that a very simple measuring arrangement allows, which one for technical purposes sufficiently precise determination of the layer thickness allowed.

Die Erfindung ist nachstehend an einen Ausführungsbeispiel beschrieben und gezeichnet. Die einzige Figur der Zeichnung zeigt das Prinzip dieses AusführungsbeispieLs in schematischer Darstellung.The invention is described below using an exemplary embodiment and drawn. The only figure in the drawing shows the principle of this exemplary embodiment in a schematic representation.

Der Strahl 11 eines He-Ne-Lasers 10 wird durch eine Chopperanordnung 12 aufgeteilt in einen Meßstrahl 14 und in einen Referenzstrahl 15, die altenierend durchgelassen bzw. abgelenkt werden. Der Strahl 14 wird nach Durchlaufen des zu untersuchenden Films 20 an der Oberfläche des Schichtträgers 21 reflektiert.The beam 11 of a He-Ne laser 10 is passed through a chopper arrangement 12 divided into a measuring beam 14 and a reference beam 15, the alternating be let through or distracted. The beam 14 is after passing through the to Examining film 20 is reflected on the surface of the substrate 21.

Der Strahl 15 dagegen wird an einer vom Film 20 freien Zone des Schichtträgers 21 reflektiert. Beide Strahlen li, 15 werden über eine einfache Spiegeloptik - bestehend aus dem Planspiegel 22 und dem halbdurchlässigen Spiegel 16 - einem Infrarot-Detektor 17 zugeführt. Im Interesse einer genauen Messung ist es erforderlich, daß die Weglängen von Meßstrahl 14 und Referenzstrahl 15 gleich sind und weitgehend senkrecht auf die reflektierenden Schichten der Nethylverbindung 20 und des Schichttra"gers 21 fallen Für beide Strahlen 14, 15 ist der gleiche Detektor 17 mit angeschlossenem Verstärker 18 zu verwenden, um Meßfehler durch Temperaturdriften zu eliminieren. Um außerdem noch mögliche 3meßfehler durch Untergrwidstrahlung auszuschalten, ist eine filodulation des Laserstrahles vorgesehen. In der dem Detektor 17 nachgeschalteten Elektronik 19 wird aus dem geschwächten Strahl 14 und dem ungeschwächten Strahl 15 ein Differenzsignal gebildet, das der Filmdicke - in Abhängigkeit von dessen Zusammensetzung - proportional ist. Der Proportionalittsfaktor ist für Jede Methylverbindung durch Eichung gesondert festzulegen.The beam 15, on the other hand, is at a zone of the layer support free from the film 20 21 reflected. Both beams li, 15 are - consisting of a simple mirror optic from the plane mirror 22 and the semitransparent mirror 16 - an infrared detector 17 supplied. In the interests of an accurate measurement, it is necessary that the path lengths of measuring beam 14 and reference beam 15 are the same and largely perpendicular to the reflective layers of the methyl compound 20 and the layer support 21 For both beams 14, 15 the same detector 17 is connected To use amplifier 18 in order to eliminate measurement errors due to temperature drift. In order to also eliminate possible measurement errors due to interference radiation, is a filodulation of the laser beam is provided. In the downstream of the detector 17 Electronics 19 is weakened from the Ray 14 and the undeatened Beam 15 formed a difference signal that the film thickness - as a function of whose composition - is proportional. The proportionality factor is for each Specify methyl compound separately by calibration.

- Patentansprüche - - patent claims -

Claims (2)

Patentansprüche Verfahren zur Schichtdickenbestimmung organischer Methylverbindungen, wie zum Beispiel Methanol, Toluol, Aceton etc., dadurch g e k e n n z e i c h n e t , daß der IR-Laserstrahl, vorzugsweise eines He-Ne-Lasers, mittels einer Chopperanordnung in einen Meßstrahl und in einen Referenzstrahl geteilt wird, wovon der Meßstrahl auf die Schicht und der Referenzstrahl auf einen unbeschichteten Teil des Trägers senkrecht auftreffen und die beiden reflektierten Strahlen einem Detektor mit nachgeschalteter Elektronik zur Bildung eines Differenzsignals zugeführt werden. Method for determining the thickness of organic layers Methyl compounds such as methanol, toluene, acetone, etc., thereby g e it is not indicated that the IR laser beam, preferably a He-Ne laser, divided into a measuring beam and a reference beam by means of a chopper arrangement is, of which the measuring beam on the layer and the reference beam on an uncoated Part of the carrier hit perpendicularly and the two reflected rays one Detector with downstream electronics supplied to form a differential signal will. 2. Anordnung zur Durchführung. des Verfahrens nach Anspruch 1, dadurch g e k e n n z e i c h n e t , daß in dem Strahlengang (11) eines IR-Lasers (10) eine Choppereinrichtung (12) und ein Planspiegel (13) angeordnet ist und den reflektierenden Strahlen (14, 15) ein halbdurchlässiger Spiege 6), ein Detektor (17) nebst Verstärker (18), sowie eine Auswertelektronik (19) zugeordnet sind. 2. Order for implementation. of the method according to claim 1, characterized it is noted that in the beam path (11) of an IR laser (10) a chopper device (12) and a plane mirror (13) is arranged and the reflective Beams (14, 15) a semi-transparent mirror 6), a detector (17) and amplifier (18) and evaluation electronics (19) are assigned. L e e r s e i t eL e r s e i t e
DE19722252527 1972-10-26 1972-10-26 Measurement of methyl compound film thickness - chopped laser beam detects variation in thickness compared to standard with no film Pending DE2252527A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19722252527 DE2252527A1 (en) 1972-10-26 1972-10-26 Measurement of methyl compound film thickness - chopped laser beam detects variation in thickness compared to standard with no film

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722252527 DE2252527A1 (en) 1972-10-26 1972-10-26 Measurement of methyl compound film thickness - chopped laser beam detects variation in thickness compared to standard with no film

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DE2252527A1 true DE2252527A1 (en) 1974-05-02

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0660075A2 (en) * 1993-12-21 1995-06-28 Minnesota Mining And Manufacturing Company High resolution high speed film measuring apparatus and method
WO2003106923A1 (en) * 2002-06-13 2003-12-24 The Boeing Company Method of measuring sol-gel coating thickness using infrared absorbance
US6784431B2 (en) 2002-06-13 2004-08-31 The Boeing Company Method of measuring anodize coating amount using infrared absorbance
US7075086B2 (en) 2003-08-28 2006-07-11 The Boeing Company Measurement of metal polish quality
US7119336B2 (en) 2003-06-20 2006-10-10 The Boeing Company Method of measuring coating using two-wavelength infrared reflectance
US7514268B2 (en) 2003-11-24 2009-04-07 The Boeing Company Method for identifying contaminants
WO2016091983A1 (en) * 2014-12-11 2016-06-16 Universite Du Maine Method for determining the thickness of a thin layer by multi-wavelength interferometry and corresponding computer program package, storage means and system

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0660075A2 (en) * 1993-12-21 1995-06-28 Minnesota Mining And Manufacturing Company High resolution high speed film measuring apparatus and method
US5506407A (en) * 1993-12-21 1996-04-09 Minnesota Mining & Manufacturing Company High resolution high speed film measuring apparatus and method
EP0660075A3 (en) * 1993-12-21 1996-06-26 Minnesota Mining & Mfg High resolution high speed film measuring apparatus and method.
WO2003106923A1 (en) * 2002-06-13 2003-12-24 The Boeing Company Method of measuring sol-gel coating thickness using infrared absorbance
US6784431B2 (en) 2002-06-13 2004-08-31 The Boeing Company Method of measuring anodize coating amount using infrared absorbance
US6797958B2 (en) 2002-06-13 2004-09-28 The Boeing Company Method of measuring sol-gel coating thickness using infrared absorbance
US7119336B2 (en) 2003-06-20 2006-10-10 The Boeing Company Method of measuring coating using two-wavelength infrared reflectance
US7075086B2 (en) 2003-08-28 2006-07-11 The Boeing Company Measurement of metal polish quality
US7514268B2 (en) 2003-11-24 2009-04-07 The Boeing Company Method for identifying contaminants
WO2016091983A1 (en) * 2014-12-11 2016-06-16 Universite Du Maine Method for determining the thickness of a thin layer by multi-wavelength interferometry and corresponding computer program package, storage means and system
FR3030032A1 (en) * 2014-12-11 2016-06-17 Univ Maine METHOD FOR DETERMINING THE THICKNESS OF A THIN LAYER BY MULTI-WAVELENGTH INTERFEROMETRY, COMPUTER PROGRAM PRODUCT, STORAGE MEDIUM AND SYSTEM THEREOF

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