EP4469765A1 - Procédé de pyrométrie à émissivité corrigée - Google Patents

Procédé de pyrométrie à émissivité corrigée

Info

Publication number
EP4469765A1
EP4469765A1 EP23702411.2A EP23702411A EP4469765A1 EP 4469765 A1 EP4469765 A1 EP 4469765A1 EP 23702411 A EP23702411 A EP 23702411A EP 4469765 A1 EP4469765 A1 EP 4469765A1
Authority
EP
European Patent Office
Prior art keywords
values
value
measured
reflectance
temperature
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
EP23702411.2A
Other languages
German (de)
English (en)
Inventor
Dirk HEYDHAUSEN
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.)
Aixtron SE
Original Assignee
Aixtron SE
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 Aixtron SE filed Critical Aixtron SE
Publication of EP4469765A1 publication Critical patent/EP4469765A1/fr
Pending legal-status Critical Current

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Classifications

    • 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
    • G01J5/0003—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiant heat transfer of samples, e.g. emittance meter
    • G01J5/0007—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiant heat transfer of samples, e.g. emittance meter of wafers or semiconductor substrates, e.g. using Rapid Thermal Processing
    • 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
    • G01J5/0003—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiant heat transfer of samples, e.g. emittance meter
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/52—Controlling or regulating the coating process
    • 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
    • G01J5/80—Calibration
    • G01J5/802—Calibration by correcting for emissivity
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/06—Apparatus for monitoring, sorting, marking, testing or measuring
    • H10P72/0602—Temperature monitoring
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
    • H10P72/76—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches
    • H10P72/7604—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches the wafers being placed on a susceptor, stage or support
    • H10P72/7618—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches the wafers being placed on a susceptor, stage or support characterised by a movable susceptor, stage or support, others than those only rotating on their own vertical axis, e.g. susceptors on a rotating carrousel
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
    • H10P72/76—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches
    • H10P72/7604—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches the wafers being placed on a susceptor, stage or support
    • H10P72/7621—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches the wafers being placed on a susceptor, stage or support characterised by supporting two or more semiconductor substrates
    • 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
    • G01J2005/0074—Radiation pyrometry, e.g. infrared or optical thermometry having separate detection of emissivity
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/04—Apparatus for manufacture or treatment
    • H10P72/0431—Apparatus for thermal treatment
    • H10P72/0432—Apparatus for thermal treatment mainly by conduction

Definitions

  • the invention relates to a method for coating a substrate with at least one layer, wherein during the deposition of the layer with at least one optical measuring device on the layer several times in succession - nander measured value pairs ⁇ UE,n U R,n ⁇ are determined that each have an emission value U E, n , which corresponds to the thermal radiation power measured at a first light wavelength, and a reflectance value U R, n , which is measured at a second light wavelength, which at most only slightly deviates from the first light wavelength , where temperature values Ti of a substrate temperature are calculated from the pairs of measured values ⁇ U E,n U R,n ⁇ , whereby the emission values U E,n and the reflectance values U R,n are each based on an angular frequency ⁇ E , ⁇ R lie over the time t oscillating curve and a quotient of the angular frequencies ⁇ E , ⁇ R is slightly different from one.
  • the temperature values Ti are preferably used as actual values T act , with which the substrate
  • the invention also relates to a device with a computing device that is programmable and is programmed in such a way that correction values are calculated.
  • the US 6,398,406 B1 forms the technical background of the invention.
  • the method of emissivity-corrected pyrometry described there also known as reflectivity- or reflectance-corrected or emissivity-compensated allows non-contact optical temperature measurement during thin film deposition with unknown and continuously changing optical properties of the measurement object.
  • the measurement object can be any optically accessible surface in the process chamber that is relevant for monitoring or controlling the temperature.
  • the measurement object is in particular the surface of the substrate or substrates in the process chamber during the deposition process, in which a semiconductor layered structure is produced with different, almost stoichiometric compounds from group III (Al, Ga, In) and from nitrogen becomes.
  • JP 2017-017251 A describes a method in which the temperature values of a substrate temperature are determined from pairs of measured values, each of which contains an emission value and a reflectance value.
  • the two sinusoidal measurement curves are slightly out of phase.
  • a transformed curve is formed by a numerical time transformation, in which minimum and maximum values of the curve are determined at different times, which is used instead of the emission values or the reflectance values when calculating the temperature values.
  • Breiland 2003 Technical Report SAND2003-1868, June 2003, publicly available e.g.: https://www. osti.gov/Biblio/ 820889 or https://prod-ng.sandia.gov/ techlib-noauth/ access-control.cgi/2003 / 031868.pdf hereinafter referred to as Breiland 2003.
  • the prior art also includes DE 10 2018 106481 A1, which describes a generic device.
  • DE 44 19476 C2 describes a method with which the emitted and reflected radiation from a substrate can be measured during the deposition of a layer.
  • DE 10 2020 111 293 A1 describes emissivity-corrected pyrometry for minimizing residual oscillation.
  • the known method of emissivity correction is based on determining the missing unknown emissivity by measuring the reflectance of the surface of the measurement object.
  • the reflectance is measured at exactly the same wavelength as the thermal emission so that the method works with sufficient accuracy.
  • the light required for this can be provided by a laser. However, the light required for this can also be generated by a diode.
  • the pyrometers do not have a sharp measuring wavelength, but indicate wavelength interval (about ⁇ 10 nm, but also narrower or wider).
  • a thermal radiation power is thus measured at a first light wavelength.
  • a reflectance value is measured at a second wavelength of light.
  • the two wavelengths of light are ideally identical, but deviate slightly from one another for technical reasons, with the deviation being in particular a maximum of 1%, 2%, 5% or a maximum of 10% of the light wavelength. In some cases it can also be larger.
  • the light source should preferably have a spectrum corresponding to the Planck distribution. This interval width and the centroid wavelength of the emission and reflectance measurements must match as closely as possible.
  • the reflectance is measured by emitting light of the defined wavelength at the location of the sensor, reflecting it at the wafer surface if it is incident vertically and reflecting it at the same location as the pyrometer measurement if possible.
  • the reflectance is determined from the measured signal intensity of the reflected light with the aid of a previous calibration.
  • the thermal emission of the object and the reflectance can often not be measured simultaneously, but rather alternately, so that the reflectance measurement does not interfere with the measurement of the thermal emission. See also the lock-in technique mentioned in DE 44 19476 C2.
  • Two different calibration steps are required for the precise measurement of the temperature; Performing the calibrations allows the determination of calibration parameters, which are included in the calculation of the temperature from the measurement signals. This involves the calibration of the emission measurement using a blackbody radiation source (blackbody oven, special reference sources), which establishes the link between the intensity signal and the measurement temperature. During the measurement, the use of the calibration parameters determined in this way allows the determination of the so-called th raw temperature.
  • An independent calibration step is used to determine a calibration parameter so that a reflectance value from the interval 0...1 is assigned to each measured reflectance signal.
  • This calibration step is carried out on substrates of well-known reflectance (or emissivity in the case of opaque substrates), such as silicon immediately after the desorption process step (native oxide removal) at a known temperature and on an uncontaminated surface and before the start of layer deposition.
  • the material system GaN (AlGaN) on silicon is particularly susceptible to the sources of error described, because the values of the refractive indices for the layer and wafer material and the meeting of the transparent layer and the opaque substrate, the measured reflectance values R oscillate between values close to zero and 0.5.
  • Other material systems can also be affected by this problem, for example the AlGaInP/GaAs system. However, a smaller effect is observed here.
  • the error sources observed can be the following errors, which also occur in practice: Unknown exact value of the reflectance of the calibration object in the reflectance calibration, so that the value of the reflectance used in the calibration does not match corresponds to the physical reflectance and the reflectance values used for the emissivity correction are incorrect; - errors in the adjustment and setup of the measuring optics; - Scattering at layer boundaries in the semiconductor layer structure when measuring the reflectance, so that part of the actually reflected light is not recorded; - Scattered radiation from hot surfaces of the process chamber, which reaches the measuring head through multiple reflections on the process chamber walls and on the wafer surface.
  • the control and repeatability of the deposition process and the yield of usable components per wafer are important in the embodiment of the known method on which the invention is based, because the measured wafer temperature is used for the temperature control in a closed control loop.
  • the temperature control regulates a heating device in such a way that the measured temperature constantly corresponds to a specific target value; the physical temperature then oscillates around the remaining amplitude of the not completely corrected temperature oscillations, which represent a measurement artifact.
  • the component has a multilayer structure deposited on a substrate, which has a first section and a second section.
  • Transition layers in particular AlGaN, and buffer layers, in particular made of GaN, are deposited in the first section.
  • An AlGaN barrier layer is deposited on the GaN buffer layer in such a way that a two-dimensional electron gas forms in the region of the layer boundary between the GaN layer and the AlGaN barrier layer.
  • the impairment in reproducibility is particularly related to the fact that the component structure is typically composed of a sequence of functional blocks consisting of a thin AlN seed layer on the Si substrate, a transition layer sequence, a thick GaN buffer layer sequence and a relatively thin but temperature-sensitive barrier layer consists of AlGaN or AlInN.
  • the deviation of the physical temperature from the target value will have different values from run to run or from wafer to wafer, which are reflected in different values of the composition critical for the function of the component transferred to the barrier layer.
  • the following theoretical correction of this measurement method is given in the prior art, which is based on a mathematically derivable fact that the effect of a number of error sources can be effectively compensated by an additional correction value Y , so that the remaining oscillations can theoretically be reduced to zero.
  • the starting point of the invention is the relationship between the measurement signal detected in the pyrometer due to the thermal emission of the wafer surface and the temperature of the wafer surface, with the non-one emissivity of the wafer surface being taken into account due to the changing physical and optical properties during layer growth.
  • U E measurement signal of the thermal emission from the wafer surface
  • U R measurement signal of the reflectance of the wafer surface
  • ⁇ emissivity
  • A,B calibration parameters, where B ⁇ 0, ⁇ : Calibration parameter of the reflectance standardization, which establishes the connection between the measurement signal UR and the physical reflectance R, with 0 ⁇ R ⁇ 1.
  • the measurement signals for the thermal emission UE and for the reflectance of the wafer surface UR are recorded in the closest possible temporal and spatial proximity.
  • the signal that corresponds to the thermal emission is the radiation intensity, which is recorded by a detector in the pyrometer and is translated into a temperature measurement value by means of the calibration parameters A and B determined with the help of a blackbody calibration carried out before commissioning.
  • the reflectance signal is generated by measuring the intensity of a light signal which, if possible, has the same wavelength as the thermal emission measurement, is sent from the measuring device and is reflected on the reflective wafer surface into the detector. Due to optical thin-film effects (Fabry-Perot effect), the reflectance of the wafer surface exhibits an approximately sinusoidal fluctuation over time during the deposition of the thin films. With the typical growth rates of 0.5 to 5 ⁇ m/h for GaN-on-Si processes and the wavelength used for the measurement of 950 nm, the oscillation periods are up to 10 minutes.
  • the pyrometer is fixedly attached to the top of the process chamber on an optical window with line of sight to a location on the surface of the substrate carrier.
  • the substrates are rotated slowly around the center of the reactor.
  • a typical rotation period is about 12 seconds, which corresponds to five revolutions per minute.
  • the rotation rate can also be greater or lesser.
  • a measurement signal pair UE and UR is therefore recorded every 12 seconds at a specific location on the wafer that is of interest for the measurement.
  • Figures 1 and 2 show the configuration used.
  • the location of the measurement 13 can also be a measurement zone over which several measurements are made.
  • the measurement signal pair UE and UR can correspond to the averaged values over this zone.
  • the location 13 or the measuring zone can lie on each wafer 7 and can be located in the center of the wafer, at the edge of the wafer or in between.
  • the wavelengths deviate from one another by a few nanometers or fractions of a nanometer, for example due to manufacturing accuracy or tolerances of the filters used.
  • the wavelength of the emission curve is temperature dependent.
  • the period length of the oscillating curves of the emission values on the one hand and the reflectance values on the other is about 300 seconds.
  • the difference between the period lengths is about 0.1 second. It can at a maximum of 0.1 seconds announce, 0.2 seconds, 0.5 seconds or a maximum of 1 second.
  • the invention is based on the object of specifying measures with which continuously transformed values can be formed.
  • the calculation of the actual value of the temperature of the substrate surface does not use the emission values and the reflectance values as such, but that either the emission values UE ,i or the reflectance values UR ,i transformed values are formed. These transformed values are then used instead of the emission values or reflectance values when calculating the actual values.
  • the transformation can be a modification of the emission value or the reflectance value. With the transformation, the curve of the emission values or the reflectance values can be mapped onto a curve that oscillates with a different angular frequency over time. The transformation can be carried out such that after the transformation two curves are available, either a transformed emission curve and the reflectance curve or a transformed reflectance curve and the emission curve, whose angular frequency is identical.
  • the curve of the measured values to be transformed is thus stretched or compressed in terms of time, so that one can speak of a time transformation of the measured values here.
  • the measured values are transformed as such. You can use to determine the transformed value Measured values are used which are measured at different times one after the other, for example measured values which are measured immediately one after the other.
  • the measured values used to calculate the transformed values contain the current measured value, ie the last measured value in each case. This value and the value measured immediately beforehand are preferably used.
  • a penultimate measured value can also be used.
  • Several measured values measured before the current measured value can also be used.
  • a value of a gradient of a curve of the measured emission values or reflectance values is calculated from at least two measured values. This slope value is used in the calculation of a transformed value.
  • a transformation factor is used in the transformation.
  • the transformation factor can be determined in preliminary tests.
  • the transformation factor can be the quotient of the angular frequencies of the curves of the reflectance values and emission values that oscillate over time. It can be provided that the transformation factor is >1, but is essentially only slightly greater than 1. Depending on the transformation approach, the transformation factor can also be less than one, but essentially only slightly less than one.
  • the value of the quotient can be, for example, in the ranges 1 - 10 -2 and 1 - 10 -6 or 1 + 10 -6 and 1 + 10 -2 .
  • time-transformed emission values or reflectance values are used to calculate the actual temperature.
  • a transformed time is formed during the time transformation, which consists of the non-transformed time and the transformation factor a and possibly a phase factor b as follows is formed.
  • the measured values are as follows converted into transformed values.
  • the transformation is preferably done using the following equation where the time derivative of the slope of the curve plotted against time is either the emissivity values or the reflectance values. which can preferably be calculated using a difference quotient. If, for example, the measured values of the reflectance U R,i are transformed, the actual temperature is calculated according to the following equation
  • the leading curve of the measured value for example the reflectance measured value
  • the leading curve of the measured value is stretched in such a way that the period length of the curve of the transformed values is the same as the period length of the trailing curve.
  • a time-transformed gradient triangle is preferably formed during the transformation. The slope of the non-transformed curve and the transformed time are determined at the time the measured value is recorded. The transformed measured value results from multiplying the slope of the non-transformed curve with the reciprocal transformation factor and the transformed time.
  • the leading curve is preferably always transformed in such a way that the period length of the transformed curve corresponds to the period length of the trailing curve.
  • an actual temperature which has a lower residual oscillation can be calculated step by step with a transformation factor a determined, for example, in preliminary tests using the current measured values and at least one measured value recorded in the past.
  • a preliminary test or several preliminary tests are carried out.
  • the same or similar process parameters with which the method with the is performed with the above features a layer is deposited on a substrate.
  • the pairs of measured values obtained in this way, each of an emission value and a reflectance value, are stored.
  • An optimization is then carried out in which a test value of a transformation factor a is varied using the stored measured values and the above-mentioned equations until the residual oscillation of the temperature curve plotted over time is minimal, i.e. e.g. the area integral under the residual oscillation curve reaches a minimum.
  • the transformation factor can also be determined during the same "run”, for example if other layers, in particular buffer layers, are deposited before the layer is deposited.
  • the constant adaptation can take place in particular when a plurality of layers are deposited one on top of the other on a substrate.
  • the transformation preferably uses a time derivative of the measurement curve plotted over time, which is formed by difference quotients.
  • the gradient of the transformed measurement curve can be calculated from the gradient of the non-transformed measurement curve.
  • the difference quotient can be calculated with the help of measured values measured in immediate succession.
  • the difference quotient is preferably calculated with consecutive measurement points. But these do not have to be the last two. Especially if the to be measured If the point in time runs out of the transformed interval, other measuring points can be used.
  • measured values can also be used which were not measured in immediate succession, but which originate from measurements that are further apart in time. The latter is used in particular when the transformed measured value lies outside an interval between the two measured values used to determine the difference quotient.
  • the measurement interval can then be stretched back in time until the transformed measured value falls within the measurement interval whose measured values are used to determine the difference quotient.
  • the temperature values calculated using the method described above represent the surface temperatures of the substrates.
  • the temperature of the substrates is preferably regulated with a temperature control device, the control circuit used for this purpose being given a setpoint value against which an actual value is regulated.
  • the temperature value calculated according to the method described above, which was calculated using the transformation, is preferably used as the actual value.
  • the invention also relates to a device for carrying out a method, the device having two optical measuring devices with which the emission value and the reflectance value can be measured. It is preferably a single measuring device that functionally embodies two optical measuring devices, which alternately measures the emission value or the reflectance value.
  • the device has a computing device for calculating the actual value of a temperature of a surface of a substrate or of the layer deposited on the substrate. The computing device is set up by means of a transformation in the above in the manner described, to form values transformed either from the emission values or from the reflectance values and to use these instead of the emission values or the reflectance values when calculating the actual values.
  • the invention also relates to a CVD reactor with a temperature control device for temperature control of a substrate, for example a heating device and a device for determining the actual value of the substrate temperature, as has been described above.
  • the CVD reactor can have a gas inlet element with which process gases can be fed into a process chamber.
  • the process gases which can be organometallic compounds of main group III and hydrides of main group V, can be introduced into the process chamber together with an inert gas, for example a noble gas or hydrogen. to be fed.
  • an inert gas for example a noble gas or hydrogen.
  • process gases which contain compounds from main groups II and VI or compounds from main group IV.
  • One or more substrates lie on a susceptor that forms the bottom of the process chamber.
  • the substrate is tempered by heating the susceptor.
  • a heating device is provided for this purpose, which can preferably be arranged below the susceptor.
  • the heating device is controlled with the computing device, specifically against an actual value which is determined from reflectance values and emission values in the manner described above.
  • the method described above can also be modified such that the time transformation is carried out either for the reflectance values or the emission values, with the sign of the transformation factor being both positive and negative.
  • Both a linear interpolation and a non-linear interpolation can be used.
  • the advantage of linear interpolation is that only two measurement points are required to determine a value in between. Higher order interpolations require more measurement points.
  • the method relates in particular to a temperature determination using a transformation. However, the invention particularly preferably relates to the determination of a temperature that is to be used as an actual value in a control circuit.
  • FIG. 1 schematically shows a device for carrying out the method
  • FIG. 2 shows a schematic of the section along the line II-II in FIG. 1 on a susceptor 4 on which substrates 7 and measuring points 13 are arranged, with which emissions are measured by means of a reflectance measuring device 11 and an emissivity measuring device 10 - values U E,i and reflectance values U R,i can be measured;
  • FIG. 3 schematically shows the time profile of a measurement curve UR recorded over time for a large number of reflectance measurement values and a measurement curve U E recorded over time for a number of emission measurement values, the curves being normalized for the sake of clarity.
  • the angular frequency ⁇ E of the measurement curve of the emission values is slightly larger than that Angular frequency ⁇ R of the measuring curve of the reflectance values. This results in an oscillation of the sum of the two normalized curves, which is shown as a dotted line and which characterizes the course of the calculated temperature;
  • Fig. 5 shows detail V in Fig. 4.
  • the CVD reactor shown in FIGS. 1 and 2 has a reactor housing 1, a heating device 5 arranged therein, a susceptor 4 arranged above the heating device 5 and a gas inlet element 2 for introducing, for example, TMGa, TMA1, NH3, AsH 3 , PH 3 and H 2 .
  • the susceptor 4 is driven in rotation about a vertical axis of rotation a with the aid of a rotary drive device 14 .
  • a drive shaft 9 is connected on the one hand to the rotary drive device 14 and on the other hand to the underside of the susceptor 5 .
  • Substrates 7 lie on the horizontal surface of the susceptor 5 pointing away from the heating device 5.
  • Substrate holders 6 are provided, on which the substrates 7 lie.
  • the substrates 7 are located radially outside the axis of rotation a and are held in position by substrate holders.
  • Two measuring devices can be provided.
  • An emissivity measuring device 12 can be formed by a pyrometer.
  • a reflectance measuring device 11 can also be formed by a pyrometer.
  • a beam splitter 10 can be provided, with which an input beam can be divided between the two measuring devices 12, 11.
  • the beam path enters the substrate 7 at a measuring point 13.
  • FIG. 2 indicates that the measuring point 13 moves over all of the substrates 7 during a rotation of the susceptor 4.
  • FIG. 1 indicates that the measuring point 13 moves over all of the substrates 7 during a rotation of the susceptor 4.
  • the two measuring devices 11, 12 can also be combined in one measuring device.
  • FIG. 3 shows an interpolated measurement curve through a large number of measured values, not shown individually, of the measured reflectance values U R,i measured with a measuring device 11 .
  • the oscillation is due to reflections at the interface layers.
  • the dashed line corresponds to a curve of the emissivity U E,i measured with the measuring device 12 and interpolated by a large number of measured values.
  • the oscillation is due to reflections at the boundary surfaces of the layer. Due to tolerances in the filters used, for example, the two curves have a path difference, so that their angular frequencies ⁇ R and ⁇ E differ slightly from one another. As a result of this deviation, the sum of the two curves oscillates. This is represented by the dotted line, which qualitatively corresponds to the course of a calculated temperature.
  • the temperature T can be calculated using Equations 1 to 2 given above according to Equation 3 given above.
  • FIG. 4 shows that due to the higher angular frequency ⁇ R of the measured curve of the reflectance values U R,i plotted over time t, this curve precedes the measured curve of the emission values U E,i .
  • a transformed curve which is shown with the dotted line, is formed from the measured reflectance values U R,i by means of a suitable transformation. Transformed measured values are used to calculate the temperature, which lie on the transformed curve at the measurement times ti. Two such pairs of measured values and a transformed measured value calculated therefrom are shown in FIG. 4, in which the index i assumes the values 1 and 2.
  • the angular frequency of the transformed curve has the same value or almost the same value as the angular frequency ⁇ E of the curve of the emission values U E,i .
  • the method for determining the transformed measured values is shown on the basis of FIG explained in detail.
  • the curves shown in FIGS. 3 and 4 do not correspond to exact sine curves. They are only indicated as sine curves in FIGS. 3, 4 and 5 for the sake of clarity. Nevertheless, the curves have a periodicity so that the angular frequencies ⁇ R and ⁇ E can be determined in preliminary tests by depositing a layer. The following quotient is obtained from these two angular frequencies educated.
  • the value a is used as a transformation factor in the transformation.
  • the transformation is a time transformation, with a transformed time is formed.
  • the solid curve UR which represents the time profile of the measured values of the reflectance U R,i , is stretched in such a way that its period length corresponds to that of the dashed curve U E , which shows the time profile of the measured values of the emissivity U E, i represents.
  • the time-transformed curve is shown dotted.
  • the transformed measured values are used to calculate the temperature T are used, which correspond to the values that the transformed curve has at the non-transformed times ti.
  • a transformed measured value is calculated using the example shown in FIG. 5 with the two measured reflectance values U R,1 and U R ,2 recorded at times t 1 and t 2 in the manner of a Taylor development, which is terminated after the first term. An amount is subtracted from the measured reflectance value U R,2 which results from the slope the transformed reflectance curve and the difference between transformed time and non-transformed time at 2 - t -2 results.
  • the slope can using the transformation factor a from the Slope of the non-transformed curve of the measured reflectance values U R,i can be obtained. so that the transformed measured value can be calculated directly from the measured value U R 2 and its time derivative as follows.
  • the time derivative is calculated by a difference quotient using at least one previously recorded measured value U R,1 .
  • Equation 10 The value calculated using Equation 10 can then be used directly to calculate the actual value T i where i has the value 2 in the exemplary embodiment and the transformed measured value is calculated using two measured values that were measured at different times t i .
  • the transformed measured value lies below between two measured values UR,1 and UR,2 taken immediately one after the other at times t1 and t2.
  • a measured value that was recorded before time t1 is preferably used in order to form the difference quotient together with the measured value UR,2 measured at time t2 , which is used to calculate the slope triangle that is used to form the transformed measured value.
  • the transformation factor a can be weakly temperature-dependent.
  • a method which is characterized in that in the calculation of the transformed values in each case at least two different Times determined measured values of the emission value U E, i or the reflectance value U R, i are used.
  • a method which is characterized in that a layer is deposited on a substrate to determine the transformation factor a with first growth parameters, while pairs of measured values ⁇ UE,n U R,n ⁇ are measured and stored during the deposition of the layer and subsequently, by means of the transformation, values transformed either from the stored emission values U E,i or from the stored reflectance values U R,i with a stepwise varied experimental value of the transformation factor a are formed, which are used instead of the emission values U E, i or the reflectance values U R, i in a calculation of a temperature value T, the test value being varied until the amplitude of a residual oscillation of a curve plotted over time according to one of the claims 1 to 9 calculated temperature value T is minimal.
  • a device which is characterized in that the arithmetic unit is set up using a transformation according to one of claims 1 to 11 of values transformed either from the emission values U E,i or from the reflectance values U R,i and to use these instead of the emission values U E,i or the reflectance values U R,i when calculating the temperature value T i .
  • a CVD reactor characterized by an apparatus for determining the temperature value T i of the substrate temperature according to claim 12.
  • Reflectance value measuring device T is actual value

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Abstract

L'invention concerne un procédé d'application de revêtement sur un substrat, selon lequel, pour réguler la température du substrat, des valeurs d'émission (UE,n) et des valeurs de réflexion (UR,n) sont déterminées au moyen de pyromètres. Puisque les longueurs d'onde des deux pyromètres sont légèrement différentes, la température brute déterminée à partir de la valeur d'émission (UE,n) ne peut pas être compensée de manière optimale par la valeur de réflectance (UR,n). Les fréquences angulaires (ωE, ωR) de la courbe oscillant dans le temps (t) des deux valeurs (UEn) et (UR,n) sont légèrement différentes l'une de l'autre, ce qui entraîne une oscillation de la valeur réelle de la température. Pour y remédier, l'invention propose d'utiliser des valeurs modifiées par une transformation de temps numérique à la place des valeurs mesurées.
EP23702411.2A 2022-01-26 2023-01-25 Procédé de pyrométrie à émissivité corrigée Pending EP4469765A1 (fr)

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DE102022101806.7A DE102022101806A1 (de) 2022-01-26 2022-01-26 Verfahren zur emissivitätskorrigierten Pyrometrie
PCT/EP2023/051819 WO2023144213A1 (fr) 2022-01-26 2023-01-25 Procédé de pyrométrie à émissivité corrigée

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DE102024100518A1 (de) * 2024-01-09 2025-07-10 Aixtron Se Verfahren zum Abscheiden eine dünne Schicht enthaltene III-V-Schichtenfolge und dazu eingerichteter Vorrichtung
DE102024126451A1 (de) 2024-09-13 2026-03-19 Aixtron Se CVD-Reaktor
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US12414402B1 (en) * 2025-01-03 2025-09-09 Conti Innovation Center, Llc Optimizing cadmium (CD) alloy solar cells with sputtered copper-dopped zinc telluride (ZNTE:CU) back contacts in the presence of hydrogen

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US5564830A (en) 1993-06-03 1996-10-15 Fraunhofer Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Method and arrangement for determining the layer-thickness and the substrate temperature during coating
US6398406B1 (en) 2000-06-01 2002-06-04 Sandia Corporation Temperature determination using pyrometry
JP2017017251A (ja) 2015-07-03 2017-01-19 株式会社ニューフレアテクノロジー 気相成長装置および温度検出方法
DE102018106481A1 (de) 2018-03-20 2019-09-26 Aixtron Se Vorrichtung und Verfahren zum Messen einer Oberflächentemperatur von auf einem drehenden Suszeptor angeordneten Substraten
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KR20240140129A (ko) 2024-09-24
DE102022101806A1 (de) 2023-07-27
WO2023144213A1 (fr) 2023-08-03

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