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WO1989003016A1 - Dispositif pour determiner l'epaisseur respective de couches de matiere variables sur un substrat - Google Patents

Dispositif pour determiner l'epaisseur respective de couches de matiere variables sur un substrat Download PDF

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Publication number
WO1989003016A1
WO1989003016A1 PCT/DE1988/000595 DE8800595W WO8903016A1 WO 1989003016 A1 WO1989003016 A1 WO 1989003016A1 DE 8800595 W DE8800595 W DE 8800595W WO 8903016 A1 WO8903016 A1 WO 8903016A1
Authority
WO
WIPO (PCT)
Prior art keywords
disc surface
flat
piezoelectric resonator
disc
quartz
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.)
Ceased
Application number
PCT/DE1988/000595
Other languages
German (de)
English (en)
Inventor
Ewald Benes
Michael Schmid
Hans-Joachim Siegmund
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.)
Balzers und Leybold Deutschland Holding AG
Original Assignee
Leybold 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 Leybold AG filed Critical Leybold AG
Publication of WO1989003016A1 publication Critical patent/WO1989003016A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/19—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator consisting of quartz
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
    • G01B7/063—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using piezoelectric resonators
    • G01B7/066—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using piezoelectric resonators for measuring thickness of coating

Definitions

  • the invention relates to a device for determining the respective thickness of changing material layers on a substrate, in particular for the production of thin layers in the optical and in the semiconductor industry, using an electrically excitable, mechanically oscillatable element with at least one pronounced resonance frequency, which is excited by an oscillator circuit at a resonance frequency to a stationary oscillation and which is acted upon in the same way as the substrate with the material.
  • Devices for in-situ measurement of layer thicknesses and coating rates are of great importance for the production of thin layers in the optical and in the semiconductor industry, since they control the layer thickness and coating rate during the coating process and thus the termination of the coating process allow when reaching a certain target value of the layer thickness.
  • Such devices often use a quartz crystal measuring head as the sensor element.
  • the quartz crystal is simultaneously coated with the substrates to be coated and changes its resonance frequency due to this foreign layer mass loading.
  • This change in resonance frequency is used as a highly sensitive measure of the applied layer thickness or for the coating rate, ie for the change in layer thickness per unit of time used. Since the resonance frequency changes in a first approximation proportional to the areal density of the foreign layer mass, the devices mentioned are also called quartz crystal microbalances.
  • These devices for measuring layer thicknesses and coating rates can basically be used for all vacuum coating processes; however, they have the greatest technical importance in the vapor deposition process. These devices are therefore also referred to as evaporation monitors.
  • oscillating quartz oscillator circuits For the vibration excitation of the layer thickness measuring quartz and for the delivery of an alternating voltage, the frequency of which is equal to the excited mechanical resonance frequency of the quartz, oscillating quartz oscillator circuits are used.
  • AT cut crystals are used as quartz crystals for the aforementioned purposes, which have a negligibly small temperature coefficient of the resonance frequency in the range between 0 ° C. and 70 ° C. Preference is given to those which have a circular geometry with a diameter of approximately 14 mm.
  • the quartz crystals also have a basic resonance frequency of slightly less than 6 MHz, and the basic resonance frequency can be set and calculated using the quartz thickness. As a rule, the thickness of the quartz is approximately 0.3 mm.
  • the oscillating region encompasses the entire quartz, but this is not desirable because the edge zone of the quartz is clamped in a holder during the layer thickness determination, which dampens the vibrations of the quartz in the edge zone.
  • the edge zones of the quartz should therefore not oscillate.
  • plano-convex crystals meet this condition. In these, only a very small area in the center is excited to vibrate, which means that the impedance at a harmonic resonance frequency has very high values.
  • a device for regulating the vapor deposition in a vacuum is also known, in which an oscillator controlled by a quartz is used (GB-PS 1 073 293).
  • the evaluation of the measurement quartz resonance frequency change takes place here by forming the difference between the sensor quartz frequency and a quartz-stabilized reference frequency via a first mixer and a subsequent difference frequency formation between this first difference frequency and an LC oscillator of variable frequency via a second mixer.
  • the AT cut that is generally used is called the thickness oscillating quartz as the preferred quartz crystal.
  • a Schwingquarzmeßküpf is known in which a measuring quartz holder is provided with a rotatable evaporation diaphragm, which diaphragm is held by a pressure spring (DE-PS 31 20 443).
  • the type of quartz crystal used, its shape and the electrode configuration are of no importance here.
  • a quartz crystal and holder together with the associated oscillator and evaluation electronics are introduced into a vacuum chamber together with the substrates on a substrate plate (DE-OS 33 15 666) .
  • the type and form of the The quartz crystal used and the electrode configuration also play no role here.
  • the invention has for its object to provide a quartz crystal for a generic device that does not vibrate in its edge zones, as well as has a low-resistance resonance behavior.
  • the mechanically oscillatable element is a disk-shaped piezoelectric resonator, one disk surface of which is flat and the other disk surface of which has an outer, convexly curved area and an inner, flat, curved plateau area.
  • the advantage achieved with the invention is, in particular, that the quality, excitability and mode purity of the Q used uarzes very high.
  • quality, excitability and mode purity can be further increased.
  • Figure 1 shows a quartz crystal according to the invention with associated electrodes in cross section.
  • FIG. 2 shows a top view of the quartz crystal according to FIG. 1 without electrodes; 3 shows a plan view of an electrode with a circular central part;
  • FIG. 5 shows a circuit arrangement for measuring an evaporated layer with the aid of the quartz crystal.
  • quartz crystal 1 shows a quartz crystal 1 according to the invention with two electrodes 2, 3 in cross section.
  • This quartz crystal 1 has a flat disk surface 4 and a second (in the drawing upper) disk surface 5, which is convexly curved in its rim region 6 and flat in its central or plateau region 7.
  • the central region 7 runs parallel to the disk surface 4.
  • a vertical reference axis is designated by 8, while the radius of curvature of the curved region 6 is provided with the reference number 9.
  • the diameter of the central area 7 is a, the diameter of the.
  • Disc surface 4 is denoted by b and the thickness of quartz 1 is denoted by c, while the diameter of lower electrode 3 is denoted by d.
  • Typical values for a, b, c and d are 5 mm, 13.95 mm, 0.277 mm and 12 mm.
  • a diaphragm 10 is shown below the quartz crystal 1, the opening diameter of which is denoted by D. This diameter D determines the area of the quartz crystal 1 to which material can be applied.
  • the electrodes are in terms of their
  • Plateau region 7 of the quartz crystal 1 is here concavely curved, whereby the radius of curvature can also be infinite.
  • the quartz crystal 1 shown from the side in FIG. 1 is shown in a top view, and specifically without electrodes.
  • the upper pane surface 5 with its curved edge region 6 can be seen here and its concavely curved or flat plateau region 7.
  • the quartz crystal 1 can be cut off at a point 11 in order to enable marking or orientation.
  • FIG. 3 shows a circular electrode 2 in individual representation.
  • a central circle 12 of approximately 5 mm in diameter can be seen, to which two narrow rectangles 13, 14 adjoin on both sides, each of which ends in small circles 15, 16 with radii of approximately 1.5 mm.
  • FIG. 4 shows how the electrode 2 is placed on the quartz 1.
  • This electrode 2 has the shape of an ellipse 19 or a circle 20 in its central region.
  • the ellipse 19 is shown in broken lines here.
  • 17 denotes the crystallographic x-axis according to IEEE Standard 176/1978, which includes an azimuth angle with an electrode axis 18.
  • the Azimuthwinkei ⁇ p is in the Fig. 4 to 30 °.
  • 1 1 again the flattening on the quartz 1 is designated, which serves as a marking of the x-axis of the quartz crystal.
  • the azimuth angle ⁇ can be set using this marker.
  • the quartz crystal 1 can be a quartz of the Hom ⁇ type or a quartz single crystal.
  • the harmonic fundamental wave resonance is preferably 6 MHz.
  • the quartz crystal 1 is provided in a circuit arrangement for measuring a vapor-deposited layer. It is a circuit arrangement in which the quartz excitation is carried out by an amplitude-controlled oscillator 21.
  • an amplifier 22 is provided, the output lines 23, 24 of which are connected to the inputs 25, 26 of a feedback network 27.
  • the output lines 28, 29 of this feedback network 27 are connected to the inputs 30, 31 of the amplifier 22.
  • the AC voltage output at the outputs 23, 24 of the amplifier 22 is rectified by a rectifier circuit 32, and the DC voltage obtained is compared with a reference voltage, which is generally derived from an operating voltage U B via an adjustable voltage divider 33 .
  • the deviation is amplified via a differential amplifier 34 and serves as control DC voltage U - GC for the amplifier 22, which has a gain dependent on the voltage applied to its control input 35 for the AC voltage applied to the amplifier input 30, 31.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

Le dispositif décrit concerne notamment la fabrication de couches minces dans l'industrie optique et des semi-conducteurs. Il comporte un élément excitable électriquement et vibrant mécaniquement avec au moins une fréquence de résonance caractéristique, qui est excité dans un circuit oscillateur à une fréquence de résonance jusqu'à obtention d'une vibration permanente et est soumis à l'action de la matière de la même manière que le substrat. Cet élément vibrant est un résonateur piézoélectrique discoïde (1) dont une face (4) est plane et dont l'autre (5) présente une région (6) extérieure à courbure convexe et une région de plateau (7) intérieure à courbure concave.
PCT/DE1988/000595 1987-09-28 1988-09-27 Dispositif pour determiner l'epaisseur respective de couches de matiere variables sur un substrat Ceased WO1989003016A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873732594 DE3732594A1 (de) 1987-09-28 1987-09-28 Einrichtung zum ermitteln der jeweiligen dicke von sich veraendernden material-schichten auf einem substrat
DEP3732594.9 1987-09-28

Publications (1)

Publication Number Publication Date
WO1989003016A1 true WO1989003016A1 (fr) 1989-04-06

Family

ID=6337023

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1988/000595 Ceased WO1989003016A1 (fr) 1987-09-28 1988-09-27 Dispositif pour determiner l'epaisseur respective de couches de matiere variables sur un substrat

Country Status (2)

Country Link
DE (1) DE3732594A1 (fr)
WO (1) WO1989003016A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB539047A (en) * 1939-04-29 1941-08-26 Marconi Wireless Telegraph Co Improvements in piezo-electric thickness-mode crystals
DE1931883A1 (de) * 1968-06-27 1970-01-08 Perkin Elmer Corp Verfahren und Anordnung zur Erzielung einer linearen AEnderung der Arbeitsfrequenz eines kristallgesteuerten Oszillators
US4124809A (en) * 1972-05-30 1978-11-07 Societe Suisse Pour L'industrie Horlogere Management Services S.A. Quartz crystal resonator
US4451755A (en) * 1982-10-18 1984-05-29 The United States Of America As Represented By The Secretary Of The Army Acceleration sensitivity reduction method
DE3412724A1 (de) * 1984-04-04 1985-10-17 Siemens AG, 1000 Berlin und 8000 München Verfahren und anordnung zum messen der schichtdicke und/oder der konzentration von auf substraten abgeschiedenen duennen schichten waehrend ihrer herstellung

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1073293A (en) * 1963-10-16 1967-06-21 Edwards High Vacuum Int Ltd Apparatus for controlling vapour deposition in a vacuum
CH644722A5 (de) * 1980-07-21 1984-08-15 Balzers Hochvakuum Schwingquarzmesskopf.
DE3315666A1 (de) * 1983-04-29 1984-10-31 Siemens AG, 1000 Berlin und 8000 München Verfahren zur messung des auftrages und abtrages von duennen schichten

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB539047A (en) * 1939-04-29 1941-08-26 Marconi Wireless Telegraph Co Improvements in piezo-electric thickness-mode crystals
DE1931883A1 (de) * 1968-06-27 1970-01-08 Perkin Elmer Corp Verfahren und Anordnung zur Erzielung einer linearen AEnderung der Arbeitsfrequenz eines kristallgesteuerten Oszillators
US4124809A (en) * 1972-05-30 1978-11-07 Societe Suisse Pour L'industrie Horlogere Management Services S.A. Quartz crystal resonator
US4451755A (en) * 1982-10-18 1984-05-29 The United States Of America As Represented By The Secretary Of The Army Acceleration sensitivity reduction method
DE3412724A1 (de) * 1984-04-04 1985-10-17 Siemens AG, 1000 Berlin und 8000 München Verfahren und anordnung zum messen der schichtdicke und/oder der konzentration von auf substraten abgeschiedenen duennen schichten waehrend ihrer herstellung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Proceedings of the Thirty-Sixth Annual Frequency Control Symposium, 2.-4. Juni 1982, Philadelphia, Pennsylvania, (US), R.C. Peach: "The design of partially controlled quartz crystal resonators", Seiten 22-28 *

Also Published As

Publication number Publication date
DE3732594C2 (fr) 1991-10-31
DE3732594A1 (de) 1989-04-06

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