TW201940850A - Device and method for measuring a surface temperature of substrates arranged on a rotating susceptor - Google Patents

Abstract

The invention relates to a method or a device for measuring a surface temperature of a substrate (7) arranged, radially offset with respect to an axis of rotation (A), on a susceptor (4) rotating about the axis of rotation (A), wherein a first optical reflectivity value (Ri) of the surface is measured at a first time (t1) at a measuring point (13) radially spaced from the axis of rotation (A), then an optical emissivity value (Ei) is measured at a second time (ti), and then a second optical reflectivity value (Ri+1) of the surface is measured at a third time (t3), wherein a temperature measurement value (Ti) is calculated from each emissivity value (Ei) and at least two reflectivity values (Ri, Ri+1) which have been measured at different times (ti, ti+1).

Description

   Device and method for measuring surface temperature of substrate arranged on rotating substrate holder   

The invention relates to a method and a measuring device for measuring a surface temperature of a substrate, which is arranged on a substrate holder rotated around the rotation axis, and is radially displaced from the rotation axis. At separate measurement points, a first optical reflectance value of the surface is measured at a first time point, then, an optical emissivity value is measured at a second time point, and then the surface is measured at a third time point. A second optical reflectance value, wherein a temperature measurement value corrected by the reflectance value is calculated from the emissivity value.

In addition, the present invention relates to a CVD reactor having a heating device, a rotation drive device that can be rotated about a rotation axis, and a plurality of CVD reactors that are arranged in particular radially offset with respect to the rotation axis. A substrate holder of a substrate accommodating portion of the substrate; a measurement point fixed on the substrate holder relative to the reactor housing and radially displaced from the rotation axis; an optical emissivity value measuring device and an optical reflectance value measuring device The measuring devices are adapted to measure the emissivity value and the reflectance value on the rotating substrate holder at the measuring points at different times; and an analysis device, which is calculated from the emissivity value corrected by the reflectance value Temperature value, or the analysis device calculates the initial temperature value from the uncorrected emissivity value, and corrects the initial temperature value by the measured reflectance value.

When manufacturing a thin semiconductor layer on a substrate, especially when manufacturing a GaN semiconductor transistor, the surface temperature is measured with a pyrometer. The surface temperature adjusting heating device can be used for heating the substrate holder carrying the substrate to the process temperature. The purpose is to achieve as uniform temperature division as possible on the surface of the substrate, even if the substrate is slightly deformed during the heat treatment. When deformation occurs, uneven contact in the radial direction between the substrate and the support surface makes the temperature uneven. When multi-zone heating is performed with different peripheral heating devices in the radial direction, different radial regions of the substrate holder can be heated to different degrees. In the rotating substrate on the rotating substrate holder, the edge region of the substrate can be heated in a different way from the center area of the substrate. In this way, different heat transfer characteristics from the substrate holder to the substrate caused by the bending of the substrate can be compensated. However, it is also possible to intentionally generate a temperature distribution that rises radially outward in order to, for example, compensate for the tensile stress generated in the silicon wafer in the circumferential direction due to the thermal expansion of the center wafer. A typical wafer has a diameter of 200 mm.

The goal of the method of the invention is to make GaN / AlGaN structures on silicon. However, in the application, all types of optoelectronic components based on GaN technology, such as GaAs or InP technology, are also manufactured, such as lasers, detectors, light-emitting diodes, solar cells or other dielectric layers. It is essentially a relatively uniformly deposited thin layer. Substrates, such as silicon substrates, are opaque with respect to the wavelength of the pyrometer, and the aforementioned layers are generally translucent with respect to the wavelength of the pyrometer.

When measuring temperature, measure the intensity of the spectral radiation emitted by the measured object, that is, the surface of the substrate or the surface of the substrate holder. According to Planck's radiation law, each radiation intensity can correspond to a temperature. However, the clear temperature correspondence is mentioned before, because the reflectivity of the layer surface does not change. The latter is related to emissivity according to Kirchhoff's law ρ = 1-ε. However, due to the translucency of the layer and the layer density, which is generally in the order of magnitude of the wavelength used for emissivity measurement, the surface reflectance or surface reflectance changes significantly during layer growth. In order to take this systematic change into consideration, not only the emissivity value but also the emissivity value is measured. This is implemented by two different measuring devices, such as a pyrometer for measuring emissivity values and light sources, and a light detector for measuring reflectance values. The light source may be a light emitting diode or a laser. The light detector may be a light sensor or a photoelectric crystal. The reflectance measurement is carried out using the same measurement wavelength, for example, 880 nm to 950 nm, wherein the emissivity value determination is also performed. The original temperature value can be determined from the emissivity value, and the original temperature value can be corrected by applying the reflectance value. In this way, the Fabry-Perot effect can be compensated. The emissivity value measurement and reflectance value measurement should be optimally performed at the same position of the measured object. However, this cannot be achieved in reality because these measurements are performed alternately to avoid mutual influence. Therefore, for example, in a pulse wave of about 100 Hz, the emissivity value is measured at a measurement point on the rotating substrate holder at a fixed position with respect to the reactor housing. Subsequently, in the pulse wave interval, the reflectance of the surface of the measured object is measured in phase shift. Since the substrate holder rotates during the measurement and the measurement point is staggered from the rotation axis by, for example, 200 mm, the measurement position on the measured object is further moved by about 1 mm to 2 mm from the time point when the emissivity value is measured to the time point when the reflectance value is measured. This makes the measured emissivity value unrelated to the measured reflectance value in position. Nevertheless, the reflectance value is still used in the prior art to correct the original temperature derived from the emissivity. For details of the described measurement methods, see W.G. Breiland, "Reflectance-Correcting Pyrometry in Thin Film Deposition Applications" 2003 (approved for public release).

US 5,326,173, US 6,349,270 and US 2016/0282188 A1 disclose devices and methods for measuring the temperature of a rotating substrate. In the case of applying a pyrometer and a light source, the reflectance value and the emissivity value are obtained on the substrate surface in chronological order, and the temperature is calculated from the reflectance value and the emissivity value.

US 2008/0036997 A1 describes a method for measuring reflectance values on a rotating substrate. The measurement time is synchronized with the rotation time of the substrate, so that the measurement device sequentially transmits the measurement values corresponding to the same position of the substrate in time.

US 2006/0171442 A1 describes a method for calibrating a pyrometer.

US 2012/0293813 A1 describes a method for measuring the reflectance value on the surface of a substrate.

The measurement methods implemented so far can lead to erroneous temperature values, especially at measurement positions located on the edge of the substrate.

The object of the present invention is to improve the same type of temperature measurement method and provide a device constructed in a related manner. This objective is achieved by applying for the invention given in the scope of the patent application. Among them, the subsidiary item is not only a beneficial improvement solution of the invention given by the parallel request item, but also an original solution for this purpose.

In the prior art, exactly one reflectance value is used to modify the emissivity value, and the present invention proposes to use several reflectance values measured at different times to modify, in particular, exactly one emissivity value. Therefore, the present invention particularly proposes that the emissivity value is measured continuously and the reflectivity value is measured in phase shift. An original temperature is preferably calculated from each emissivity value. The original temperature is corrected by applying at least two reflectance values measured at different points in time. In this process, correction is performed by measuring the average of the two reflectance measurements. Preferably, the first reflectance measurement value is measured before the emissivity value, and the second reflectance measurement value is measured after the emissivity value. An average value of the two reflectance values may be obtained in order to correct the original temperature obtained from the emissivity values measured at the time points between the two time points of the reflectance value. The above-mentioned averaging may also refer to the weighted average. The two time points used to determine the reflectance value for correction are preferably temporally close to the time point at which the emissivity value is measured. The correction / value can be calculated / calculated by linear interpolation or higher-order interpolation between several successively recorded reflectance measurements. The temperature values obtained in the previous method can be used to adjust the heating device.

The CVD reactor of the present invention has a substrate holder which can be heated by a heating device. The substrate holder can rotate around a vertical axis. For this purpose, a rotation driving device is provided, which rotates the rod portion of the substrate holder, so that the substrate holder fixedly connected to the rod portion rotates around the driving shaft. The heating device is preferably arranged below the substrate holder. The heating device may be an RF heating device, an IR heating device, or other heating devices. A plurality of substrate accommodating portions are provided on the top side of the substrate holder facing away from the heating device. The substrate accommodating portion may be a groove on the top side of the substrate holder for the substrate to be embedded. However, the substrate accommodating portions may also be protrusions for adjusting the position. The substrate accommodating portion is preferably staggered radially from the rotation axis so that it is arranged eccentrically on the substrate holder on which the substrate is fixed. A process chamber is provided above the substrate, and the process chamber faces upward and is restricted by the top of the process chamber. A gas inlet member is provided for feeding process gases, such as hydride of main group V and organometallic compound of main group III, into the process chamber. The process gas is preferably fed together with a carrier gas, such as hydrogen. The gas inlet member may be arranged in the center of the process chamber. However, the gas inlet member may also extend over the entire top of the process chamber in a shower head shape. There are two measuring devices: a first measuring device that can be used to measure the emissivity value, and a second measuring device that can be used to measure the reflectance value at a measurement position on the surface of the substrate or substrate holder. The measuring device is preferably an optical measuring device, such as a pyrometer, a photoelectric crystal, or a photodiode. In addition, a light source can be applied for emissivity measurement. For example, the beam splitter can be used to make the two optical measuring devices have the same optical path, and the optical path is preferably parallel to the rotation axis. This measurement can be performed through the top of the process chamber. For this reason, the top of the process chamber preferably has an opening. The "measurement ray" determined by the optical path preferably hits a measurement point that is fixed on the substrate holder that is rotated during the measurement relative to the reactor housing, so that as far as the reference frame of the substrate holder is rotated, the measurement The point moves on a circular trajectory around the center of rotation of the substrate holder. Therefore, the measurement device measures several measurement values at measurement positions spaced apart from each other in the circumferential direction around the center of rotation of the substrate seat on the circular arc, and each of them has an emissivity measurement position arranged at two reflectance measurement values Between locations. The measuring point can be separated from the rotation axis to a degree exceeding half the radius of the substrate holder. The circular arc line (the measurement position is on the circular arc line) can pass through the center of the preferably round substrate. However, the arc line can also extend outside the center of the substrate, and especially through the edge of the substrate. Several sensor pairs can be set at different radial distances, wherein each sensor pair has a sensor for measuring the emissivity value and a sensor for measuring the reflectance value. The device of the present invention has an analysis device for determining an original temperature measurement value from an emissivity value. An original temperature is determined for each emissivity value. The original temperature is a corrected value obtained by applying at least two measured reflectance values measured at two different measurement positions on a rotating substrate base, and the original temperature is corrected to a temperature value by the corrected value . The device of the present invention is, in particular, a measuring device for measuring a surface temperature. The device has an analysis device which uses an emissivity value and at least two reflectivity values to determine a temperature value.

1‧‧‧reactor housing

2‧‧‧Gas inlet member

3‧‧‧Gas transmission pipeline

4‧‧‧ substrate

5‧‧‧Heating device

6‧‧‧ substrate rack

7‧‧‧ substrate

8‧‧‧ Cover

9‧‧‧ rotation axis

10‧‧‧ Emissivity value measuring device

11‧‧‧Reflectivity value measuring device

12‧‧‧ray conductor

13‧‧‧ measuring points

14‧‧‧ Rotary Drive

A‧‧‧rotation shaft

E‧‧‧emissivity value

E _i ‧‧‧ emissivity value

E ₁ ‧‧‧ emissivity value

E ₂ ‧‧‧ emissivity value

E ₃ ‧‧‧ emissivity value

E ₄ ‧‧‧ emissivity value

L‧‧‧circle

R‧‧‧Reflectivity value

Ri‧‧‧Reflectivity value

R ₁ ‧‧‧Reflectivity value

R ₂ ‧‧‧Reflectivity value

R ₃ ‧‧‧Reflectivity value

R ₄ ‧‧‧Reflectivity value

T‧‧‧Temperature

T _i ‧‧‧Temperature measurement value

T ₁ ‧‧‧Temperature measurement

T ₂ ‧‧‧Temperature measurement

T ₃ ‧‧‧Temperature measurement

T ₄ ‧‧‧Temperature measurement

t ₁ ‧‧‧time

t ₂ ‧‧‧time

t ₃ ‧‧‧time

t ₄ ‧‧‧time

t ₅ ‧‧‧time

t ₆ ‧‧‧time

t ₇ ‧‧‧time

t ₈ ‧‧‧time

The embodiments of the present invention will be described below with reference to the drawings. Among them: FIG. 1 is a schematic cross-sectional view of a first embodiment of a CVD reactor for implementing the method of the present invention, and FIG. 2 is, for example, looking at the substrate holder 4 along the cutting line II-II in FIG. Top view of the substrate 7 on the top, FIG. 3 is a view corresponding to FIG. 1 of the second embodiment, FIG. 4 is a view corresponding to FIG. 2 of the second embodiment, and FIG. 5 is along the line L in FIGS. 2 and 4 The form measured through the angular position is the reflectivity value R of the curve, Fig. 6 is the time sequence of the emissivity value E and the reflectance value R, and Fig. 7 is the reflection measured at different times t ₁ to t ₇ Schematic diagram of emissivity value R, emissivity value E, and temperature T calculated from it.

The CVD reactors shown in FIGS. 1 to 4 each have a reactor housing 1, a heating device 5 arranged in the reactor housing, a substrate holder 4 arranged above the heating device 5, and for introducing, for example, TMGa , TMA1, NH ₃ , AsH ₃ , PH ₃ and H ₂ gas inlet member 2. The substrate holder 4 is rotationally driven by a rotation driving device 14 around a vertical rotation axis A. For this purpose, one side of the drive shaft 9 is connected to the rotary driving device 14, and the other side is connected to the bottom side of the substrate holder 4.

The substrate 7 is placed on a horizontal surface of the substrate holder 4 facing away from the heating device 5. The substrate 7 is located radially outside of the rotation axis A and is held in a suitable position by a substrate accommodating portion which is composed of a cover portion 8 or a substrate holder 6.

Two measuring devices are provided, one of which is an emissivity value measuring device 10 that measures the emissivity value by a pyrometer. The second measuring device 11 is also an optical measuring device. The measuring device has a light detector and a light source. The light source may be a laser. The photodetector is a photoelectric crystal. The reflectance value is measured by the reflectance value measuring device 11. The emissivity value and reflectivity value of the present invention can be obtained by the two measuring devices 10 and 11. The "measurement rays" of the two measuring devices 10, 11 are concentrated into a vertical measuring ray through the beam splitter 12, and the rays hit the substrate 7 or the substrate holder at the measuring point 13 fixed in position with respect to the reactor housing 1. 4 的 表面。 4 of the surface. Therefore, the measurement device 10, 11 measures the emissivity value E and the reflectance value R of the substrate surface.

Since the substrate holder 4 rotates around the rotation axis A during the measurement, the measurement values at the measurement positions on the circumference L can be measured by the measurement devices 10 and 11.

The emissivity value E is measured by the emissivity value measuring device 10 at periodic continuous time points t ₂ and t ₄ (see FIG. 6). The reflectance value R is measured at time points t ₁ , t ₃ , and t ₅ between two time points t ₂ , t ₄ of the measured emissivity value. Due to this phase shift between the measurement of the emissivity value and the measurement of the reflectance value, the measurement positions on the top side of the substrate holder, particularly on the top side of the substrate, are staggered from each other in the circumferential direction on the line L. For example, the positions indicated by X in FIG. 2 and FIG. 4 represent the measurement positions for the measurement of the emissivity value, and the positions indicated by the open circles are the measurement positions for the measurement of the reflectance value.

In the CVD reactor shown in FIG. 1, the substrate 7 can also be rotated around a substrate rotation axis. For this purpose, the substrate is on a substrate holder 6 which can be rotated about this axis. Therefore, the line L for measuring position arrangement shown in FIG. 2 is more complicated in reality than the line shown for convenience in FIG. 2. This line forms a cycloid on the surface of the substrate.

The present invention is based on the recognition that the reflectance value R shown in FIG. 5 changes greatly in the radial direction with respect to the center of the substrate in the region of the edge of the substrate 7. The reflectance value changes only slightly in the center region of the substrate 7 along the line passing through the center, and the reflectance value changes more greatly on the edge of the substrate on a straight line passing through the diameter of the substrate. The difference between the two measured values of the reflectance measured at the equally spaced measurement positions in the edge region is greater than in the center region.

The lower curve in FIG. 7 qualitatively shows the direction of the substrate surface in the radial direction, that is, the time-dependent direction in the measurement point of the substrate moving in the radial direction. The open circles represent the reflectance values R ₁ , R ₂ , R ₃ , and R ₄ measured at times t ₁ , t ₃ , t _5, and t ₇ . Between these times, emissivity values E ₁ , E ₂ , E ₃ and E ₄ were measured at times t ₂ , t ₄ , t ₆ , and t ₈ , respectively. As shown in the figure, the reflectance value R ₁ used to correct, for example, the emissivity value E ₁ is too low, and the measured value used for the correction of the reflectance value R ₂ is too high. According to the present invention, the two adjacent measured values of the reflectance values R ₁ and R ₂ constitute an intermediate value R _{1 ′} or an interpolated value, which is shown as a solid square in FIG. 7. To determine the reflectance value for correction at time t ₆ for correcting the emissivity value E ₃ , an interpolation value or an intermediate value can also be used, wherein the intermediate value of the reflectance values R ₃ and R ₄ is used for this purpose. The correction value R _{4 '} can also be calculated by averaging.

The reflectance correction value R _{2 ′} for correcting the emissivity value E ₂ at time t ₄ is calculated by a quadratic interpolation method. For this reason, not only the reflectance values R ₂ and R ₃ measured at times t ₃ and t ₅ immediately adjacent to the correction time point t ₄ but also the reflectance values R measured at times t ₁ and t ₇ are applied. ₁ and R ₄ .

By correcting the emissivity values E ₁ , E ₂ , E ₃ , and E ₄ by interpolation in this way, the temperature values T ₁ , T ₂ , T _3, and T ₄ that can be used to adjust the heating device 5 can be determined.

The foregoing embodiments are used to describe the inventions included in the present application as a whole. These inventions independently constitute an improvement scheme relative to the prior art through at least the following feature combinations, among which two, several or all of these feature combinations may also be combined with each other, namely: a method or an apparatus, wherein: the application and the emissivity value E _i at a plurality of different times t _i, t _{i + 1} to obtain the measured reflectance values R _i, R _{i + 1} To calculate the temperature value T _i .

A method for measuring the surface temperature of a substrate 7 arranged on a substrate holder 4 rotating around a rotation axis A, in which the surface is periodically and continuously measured at a measurement point 13 radially spaced from the rotation axis A The optical emissivity value E _i on the surface and the optical reflectance value R _{i of} the surface are measured in phase shift, and each emissivity value (E _i ) is calculated by applying at least two at different time points t _i , Reflected values R _i , R _{i + 1} corrected temperature values measured at t _{i + 1} .

A method or an apparatus, wherein: the reflectance value R _i, R _{i + 1} of the application comprises averaging.

A method or a device, characterized in that the averaging is a weighted average.

A method or an apparatus, characterized in that the time points at which the reflectance values R _i , R _{i + 1} for correction are measured are immediately adjacent to the time points at which the emissivity value E _{i is} measured.

A method or an apparatus, comprising: calculate the actual values of reflectance, the reflectance value R _i through, linear interpolation R _{i + 1} of the interpolation calculation or the actual value of the higher order reflectance.

A method or a device, characterized in that the temperature measurement value T _{i is} used to adjust the heating device 5.

A method or a device, characterized in that the measuring device (10) for measuring the emissivity value E _i is a pyrometer 10, and the measuring device (11) for measuring the reflectivity value Ri includes an LED and a light Detector.

A method or a device, characterized in that the optical paths of the two measuring devices 10 and 11 are the same.

A CVD reactor, characterized in that the analysis device 15 is adapted to calculate the temperature value T _i using at least two reflectivity values R _i , R _{i + 1} .

A method, a device, or a CVD reactor, characterized in that when several reflectivity values R _i , R _{i + 1} are applied, exactly one temperature value is calculated from exactly one emissivity value E _i .

A measuring device, characterized in that the analysis device 15 is adapted to calculate the temperature value T _i using at least two reflectance values R _i , R _{i + 1} .

All the disclosed features (as a single feature or a combination of features) are the essence of the invention. Therefore, the disclosure content of this application also includes all the content disclosed in the related / attached priority files (copy of the previous application), and the features described in these files are also included in the scope of patent application of this application. The subsidiary items describe the features of the present invention's improvements to the prior art with their characteristics (there are no features of the related claims), and their main purpose is to make a divisional application based on these claims. The invention given in each claim may further have one or more of the features given in the foregoing description, especially marked with a symbol and / or given in the symbol description. The present invention also relates to a design form in which individual features mentioned in the foregoing description are not realized, especially features that are not necessary for a specific use or can be replaced by other components that have the same technical effect.

Claims (12)

A method or device for measuring the surface temperature of a substrate (7) arranged on a substrate holder (4) rotating around a rotation axis (A), in which measurement points are spaced radially from the rotation axis (A) (13), measure the first optical reflectance value (R ₁ ) of the surface at a first time point (t ₁ ), and then measure the optical emissivity value (E ₁ ) at a second time point (t ₂ ) ), And then a second optical reflectance value (R ₂ ) of the surface is measured at a third point in time (t ₃ ), where each emissivity value (E _i ) is calculated from the reflectance value ( R _i ) corrected temperature measurement value (T _i ), which is characterized by applying the emissivity value (E _i ) and several reflectance values (R _i ) measured at different times (t _i , t _{i + 1} ) , R _{i + 1} ) to calculate the temperature value (T _i ). A method or device for measuring the surface temperature of a substrate (7) arranged on a substrate holder (4) rotating around a rotation axis (A), in which measurement points are spaced radially from the rotation axis (A) (13), the optical emissivity value (E _i ) on the surface is continuously and periodically measured and the optical reflectance value (R _i ) on the surface is measured in phase shift, and each emissivity value (E _i ) A temperature value corrected by applying at least two reflectance values (R _i , R _{i + 1} ) measured at different time points (t _i , t _{i + 1} ) is calculated. The method or device of claim 1 or 2, wherein the application of the reflectance values (R _i , R _{i + 1} ) includes averaging.     The method or device of claim 1 or 2, wherein the averaging is a weighted average.     The method or device as claimed in claim 1 or 2, wherein the time points at which the reflectance values (R _i , R _{i + 1} ) for correction are measured are immediately adjacent to the time at which the emissivity value (E _i ) is measured. Wait for time. If the method or device of claim 1 or 2, wherein the actual reflectance value is calculated, the actual reflectance value is calculated by linear interpolation or high-order interpolation of the reflectance values (R _i , R _{i + 1} , ...) . The method or device of claim 1 or 2, wherein the temperature measurement value (T _i ) is used to adjust the heating device (5). The method or device of claim 1 or 2, wherein the measuring device (10) for measuring the emissivity value (E _i ) is a pyrometer (10) for measuring the reflectance value (R _i ) The measuring device (11) includes an LED and a light detector.     For example, the method or device of claim 1 or 2, wherein the optical paths of the two measuring devices (10, 11) are the same.     A CVD reactor comprising: a heating device (5) which can be heated by a rotation drive device (14) about a rotation axis (A); and a plurality of CVD reactors which are arranged radially offset from the rotation axis (A). A substrate holder (4) for fixing a substrate accommodating part of the substrate (7); the position is fixed relative to the reactor housing (1) and radially displaced from the rotation axis (A) on the substrate holder (4) (13); optical emissivity value measuring device (10) and optical reflectance value measuring device (11), which are suitable for measuring at different times (t _i , t _{i + 1} ) Measure the emissivity value (E _i ) and reflectance value (R _i , R _{i + 1} ) on the rotating substrate holder (4) at the measuring point (13); and the analysis device (15), which is composed of The reflectance values (R _i , R _{i + 1} ) and the emissivity values (E _i ) are used to calculate the temperature value (T _i ), which is characterized in that the analysis device (15) is suitable for applying at least two reflectance values (R _i , R _{i + 1} ) to calculate the temperature value (T _i ). The method or device as claimed in claim 10 or the CVD reactor as claimed in claim 10, wherein in the case where several reflectance values (R _i , R _{i + 1} ) are applied, exactly one emissivity value (E ₁ ) Calculate exactly one temperature value. A measuring device for measuring the surface temperature, which has an emissivity value measuring device (10) for measuring the emissivity of the surface at a measuring point (13), and a measuring device for measuring the surface at the measuring point (13). A reflectance value measurement device (11) for reflectance, and an analysis device (15), characterized in that the analysis device (15) is adapted to apply at least two reflectance values (R _i , R _{i + 1} ) to calculate temperature Value (T _i ).