WO1994029681A1 - Determination simultanee de l'epaisseur des couches et de la temperature du substrat pendant une operation d'enduction - Google Patents

Determination simultanee de l'epaisseur des couches et de la temperature du substrat pendant une operation d'enduction Download PDF

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Publication number
WO1994029681A1
WO1994029681A1 PCT/DE1994/000168 DE9400168W WO9429681A1 WO 1994029681 A1 WO1994029681 A1 WO 1994029681A1 DE 9400168 W DE9400168 W DE 9400168W WO 9429681 A1 WO9429681 A1 WO 9429681A1
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WO
WIPO (PCT)
Prior art keywords
temperature
radiation
substrate
detector
light source
Prior art date
Application number
PCT/DE1994/000168
Other languages
German (de)
English (en)
Inventor
Friedrich BÖBEL
Norbert Bauer
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority to DE59407307T priority Critical patent/DE59407307D1/de
Priority to EP94906879A priority patent/EP0701686B1/fr
Publication of WO1994029681A1 publication Critical patent/WO1994029681A1/fr

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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
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/60—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature

Definitions

  • the technical field of the invention is the temperature and layer thickness measurement during the coating process of substrates with known coating technologies in semiconductor manufacturing systems, plasma, ion and other dry etching systems and in the production of optical layers.
  • the substrate temperature determines the crystallization behavior, characterizes the growth rate, diffusion rate, etc. and influences thermodynamic, chemical and physical processes equally.
  • temperature measurements are therefore of outstanding importance.
  • the emissivity ⁇ changes constantly during the coating, so that a pyrometric temperature measurement cannot be used.
  • the pyrometric temperature measurement on multilayer systems is particularly problematic, the current emissivity of which depends on the thickness of all layers, their optical constants, the temperature dependencies of the optical constants, the observation angle and the observation wavelength.
  • a laser or a monochromatized other light source for example one
  • Halogen lamp with an upstream interference filter can be used together with an associated detector, the detector being used for the reflected radiation to measure the emissivity of the coated substrate which is dependent on the respective layer thickness.
  • the transmission wavelength of the filter and the wavelength of the laser or the monochromatized light source as well as the observation angle should be the same.
  • the invention of the in situ temperature determination is based on the physical relationships shown below.
  • the temperature radiation emitted by the substrate is repeatedly reflected and refracted on the growing layer.
  • R Q can be determined as a reflection of the uncoated substrate by measurement, calibration or from the literature.
  • the initial temperature T Q can, for. B. determine by simple pyrometry.
  • Radiation from a light source is measured by one detector each, with a phase-sensitive modulation technique belonging to each detector ensuring that in a detector branch A only the radiation of the light source reflected by the substrate is proportional to the reflectivity R and in the second detector branch B only the thermal radiation is proportional to ⁇ 'fpianck is measured.
  • the "branches" can be seen in the course of the beam path, the branch A light source - substrate - reflectometer - first detector and the branch B substrate - second detector in the beam path.
  • the phase-sensitive modulation technique consists of a chopper, which is connected to a lock-in amplifier, with a phase difference of ⁇ between chopper A of the light source and chopper B in front of the detector for thermal radiation, and the gap width of chopper A approximately 3 to 7 times smaller than with Chopper B. This means that neither reflected nor scattered radiation from the light source reaches the thermal detector.
  • light is provided in a narrow first frequency band with a first chopper, and the thermal radiation is modulated into a second frequency band with a second chopper.
  • Frequency components around fl (from the reflected radiation) and very low-frequency (practically DC) components (from the thermal radiation) are therefore present at the detector in the reflectometer branch A for the reflected radiation.
  • the associated lock-in amplifier only registers signals that are in a narrow band around fl. The low-frequency thermal components are therefore filtered out. A signal proportional to the reflectivity R is thus present at the output of this lock-in amplifier.
  • the detector branch B for the substrate radiation the thermal radiation being modulated by the associated chopper into a frequency range around f2, while the reflected radiation is present in the frequency ranges fl + f2 and fl-f2.
  • the second lock-in amplifier suppresses all components that are not in a narrow frequency band around f2. If fl and f2 are chosen to be sufficiently far apart, the output voltage at this lock-in amplifier is proportional to ⁇ "f Planck •
  • Analog or digital signal processing can be connected to the detectors, which processes the signals from the signals in real time using the evaluation rule according to equation (1)
  • the temperature T determined in this way can be used for process control or regulation.
  • the measuring device according to the invention (claim 5) consists of a reflectometer branch A and a substrate radiation branch B for measuring the intensity of the thermal substrate radiation.
  • a first detector is provided in the substrate radiation branch B and a second detector in the reflectometer branch A for detecting the radiation emitted by a light source and reflected by the wafer.
  • Reflectometrastes and the thermal radiation of the substrate takes place through the same or identical filters.
  • a chopper and a lock-in amplifier are assigned to each detector.
  • the measuring device can be constructed so that the angle of incidence of the reflectometer light and the
  • Monochromatic sources such as lasers or white light sources in the form of globar rods (SiC), blackbody emitters, halogen lamps, etc., can be used as light sources. be used.
  • the method according to the invention is distinguished from conventional measuring methods by a number of surprising advantages: -
  • the determination of the emissivity ⁇ is completely independent of any prior knowledge of the material, ie neither the optical constants nor the thicknesses of the applied layers are required for a temperature measurement.
  • Layer thickness configuration Semiconductors (Si, GaAs, InP, InSb, HgTe, CdTe as well as ternary and quaternary systems) and insulators are just as suitable as metal layers; the thickness of the applied layers may be between an atomic layer and several hundred ⁇ m.
  • the evaluation takes place in real time. This means that the process can also be used to control rapidly changing processes (e.g. in RTP systems [Rapid Thermal Processing]).
  • the temperature measurement is not falsified by the interference oscillations of the temperature radiation on the growing layer d (t).
  • Figure 1 shows the basic representation of an example of a measuring device according to the invention.
  • this measurement set-up which converts the aforementioned equation (1) for determining the temperature T, comprises the following components:
  • the intensity of the thermal radiation of the substrate 1 is monochromatized by a narrow-band interference filter 3 and measured by means of a first detector 7 for evaluating the substrate radiation, which is sensitive at the corresponding wavelength.
  • the directional radiation from a light source 6 is also monochromatized by the same or - if one distributes two interference filters to the two (optical) detector branches A and B - a filter of the same transmission and irradiated onto the substrate 1.
  • the reflected light is measured by a second detector 8.
  • the beam path in the measuring system and thus the arrangement of the components lens 2, filter 3, beam splitter 4.1 and 4.2, lens 5 is designed such that both the thermal radiation and the reflected radiation from the light source 6 impinge on both detectors 7, 8.
  • lens 2, filter 3, beam splitter 4.1 and 4.2, lens 5 is designed such that both the thermal radiation and the reflected radiation from the light source 6 impinge on both detectors 7, 8.
  • each detector is assigned an optical modulator (chopper) 9, 11 and a lock-in amplifier 10, 12.
  • chopper optical modulator
  • lock-in amplifier 10 only registers the signals which lie in the frequency band around fl; thus there is a signal at the output of this lock-in amplifier 10 which is proportional to the reflectivity R.
  • the thermal radiation of the substrate 1 is received in an analogous manner by the detector 7, which was modulated by means of chopper 11 into a frequency range around f2.
  • the output voltage at the lock-in amplifier 12 is here proportional to ⁇ -fpianck. The further evaluation takes place on the basis of equation (1).
  • the measurement setup explained represents only one of several possibilities.
  • the direction of incidence of the radiation need not be perpendicular.
  • the two detector branches A and B will be spatially separated from the light source.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Radiation Pyrometers (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

L'invention décrit un procédé et un dispositif permettant de mesurer la température et l'épaisseur des couches pendant le processus d'enduction avec des technologies d'enduction connues employées dans les installations de fabrication de semi-conducteurs, les installations d'attaque au plasma, d'attaque ionique et autres installations d'attaque par voie sèche, ainsi que pour la fabrication de couches optiques. Les valeurs obtenues dans les mesures d'épaisseur de couche et de température peuvent être employées pour la commande de processus. Par suite des phénomènes d'interférence du rayonnement thermique du substrat sur la couche épitaxiale, l'émissivité ε se modifie constamment pendant l'enduction, de sorte qu'il n'est pas possible d'appliquer une mesure pyrométrique de la température. La mesure pyrométrique de la température soulève plus particulièrement des problèmes dans le cas de systèmes multicouches, dont l'émissivité effective dépend de l'épaisseur de toutes les couches, de leur constante optique, de la variation des constantes optiques en fonction de la température, de l'angle d'observation et de la longueur d'onde de l'observation. Ce problème de base est résolu avec la présente invention par le fait qu'on détermine avec un réflectomètre la réflectivité R de la tranche. En raison du principe de conservation de l'énergie on a, pour les substrats non transparents, ε = 1 - R, de sorte que l'émissivité effective de l'ensemble du système multicouches est déterminée directement avec le réflectomètre. La mesure de la température s'effectue ensuite par une consigne d'évaluation calculée, tandis que l'épaisseur est déterminée par une comparaison de la courbe du réflectomètre avec la dépendance théorique par rapport à l'épaisseur des couches.
PCT/DE1994/000168 1993-06-03 1994-02-16 Determination simultanee de l'epaisseur des couches et de la temperature du substrat pendant une operation d'enduction WO1994029681A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE59407307T DE59407307D1 (de) 1993-06-03 1994-02-16 Gleichzeitiges bestimmen von schichtdicke und substrattemperatur während des beschichtens
EP94906879A EP0701686B1 (fr) 1993-06-03 1994-02-16 Determination simultanee de l'epaisseur des couches et de la temperature du substrat pendant une operation d'enduction

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE4318520 1993-06-03
DEP4318520.7 1993-06-03
DE9400020 1994-01-11
EPPCT/DE94/00020 1994-01-11

Publications (1)

Publication Number Publication Date
WO1994029681A1 true WO1994029681A1 (fr) 1994-12-22

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DE (1) DE59407307D1 (fr)
WO (1) WO1994029681A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19843891A1 (de) * 1998-09-24 2000-04-20 Wacker Chemie Gmbh Verfahren zur Bestimmung des Temperaturprofils eines zylindrischen Stabes aus einem Halbleitermaterial
EP2503021A1 (fr) 2011-03-24 2012-09-26 United Technologies Corporation Surveillance de la température d'un substrat.

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0408015A2 (fr) * 1989-07-13 1991-01-16 Dainippon Screen Mfg. Co., Ltd. Méthode pour mesurer l'épaisseur d'un film
US5029117A (en) * 1989-04-24 1991-07-02 Tektronix, Inc. Method and apparatus for active pyrometry
US5156461A (en) * 1991-05-17 1992-10-20 Texas Instruments Incorporated Multi-point pyrometry with real-time surface emissivity compensation
WO1992019944A1 (fr) * 1991-04-29 1992-11-12 Luxtron Corporation Techniques d'optique sans contact utiles pour mesurer les caracteristiques de surface d'un substrat
US5180226A (en) * 1991-10-30 1993-01-19 Texas Instruments Incorporated Method and apparatus for precise temperature measurement

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5029117A (en) * 1989-04-24 1991-07-02 Tektronix, Inc. Method and apparatus for active pyrometry
EP0408015A2 (fr) * 1989-07-13 1991-01-16 Dainippon Screen Mfg. Co., Ltd. Méthode pour mesurer l'épaisseur d'un film
WO1992019944A1 (fr) * 1991-04-29 1992-11-12 Luxtron Corporation Techniques d'optique sans contact utiles pour mesurer les caracteristiques de surface d'un substrat
US5156461A (en) * 1991-05-17 1992-10-20 Texas Instruments Incorporated Multi-point pyrometry with real-time surface emissivity compensation
US5180226A (en) * 1991-10-30 1993-01-19 Texas Instruments Incorporated Method and apparatus for precise temperature measurement

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"DIELECTRIC FILM THICKNESS MEASUREMENT FROM THE REFLECTION RELATIONS", SOLID-STATE ELECTRONICS, vol. 18, no. 1, 1975, pages 110 - 111 *
Z-H CHEN ET AL.: "EMISSIVITY CORRECTION IN INFRARED MICROTHERMOGRAPHY", MEASUREMENT, vol. 11, no. 1, March 1993 (1993-03-01), LONDON GB, pages 55 - 64 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19843891A1 (de) * 1998-09-24 2000-04-20 Wacker Chemie Gmbh Verfahren zur Bestimmung des Temperaturprofils eines zylindrischen Stabes aus einem Halbleitermaterial
EP2503021A1 (fr) 2011-03-24 2012-09-26 United Technologies Corporation Surveillance de la température d'un substrat.
US9464350B2 (en) 2011-03-24 2016-10-11 United Techologies Corporation Deposition substrate temperature and monitoring

Also Published As

Publication number Publication date
DE59407307D1 (de) 1998-12-24

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