JP2007040981A - Method and device for measuring wafer temperature - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measuring a wafer temperature that is a non-contact type and locally and precisely measures a wafer temperature even in a low temperature process. <P>SOLUTION: The device measures a wafer temperature on the basis of reflected light that is irradiated to a wafer of an object to be temperature-measured and then reflected. The device includes a light source 110 that generates light containing a P-polarization component with a wavelength of 400 nm or less and irradiates the light to the wafer 100, a light receiver 130 that receives light that is reflected by the wafer to detect at least strength of the P polarization component with the wavelength of 400 nm or less, and a signal processor 150 calculates a temperature of the object based on the strength of the P-polarization component detected by the light receiver. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer temperature measuring method and a wafer temperature measuring apparatus used for controlling the temperature of a wafer in a semiconductor manufacturing process.

In recent years, with the miniaturization of semiconductor devices, it has become increasingly important to precisely control the wafer temperature in the semiconductor manufacturing process.
At present, a method using a radiation thermometer is the mainstream method for measuring the wafer temperature. This measurement method is a method of measuring temperature by detecting thermal radiation emitted from a measurement object, and can measure temperature without contact with a wafer. According to this measuring method, the temperature can be measured with high accuracy in the range of about 300 ° C. or higher, and therefore, it is mainly used in a high temperature process of about 800 ° C. to 1000 ° C. However, the problem with this measurement method is that the accuracy decreases at an accelerated rate as the temperature of the measurement object decreases. For example, when the measurement target is 200 ° C. or lower, the temperature can hardly be measured. The reason is that while the wavelength peak of thermal radiation is in the infrared region at low temperatures, the silicon semiconductor is transparent in that region, making it difficult to detect thermal radiation from the silicon semiconductor. .

  Therefore, at present, in a low-temperature process of about 100 ° C. to 200 ° C., the wafer temperature is measured by arranging a temperature sensor in the vicinity of the wafer to be measured. However, this measurement method has a problem that temperature cannot be measured with high accuracy due to contact thermal resistance. For example, in a liquid or solid, even if the contact between the wafer to be measured and the temperature sensor is somewhat poor, the liquid or solid plays a role of heat conduction, so it is possible to maintain a certain degree of accuracy. . However, since such heat conduction is not performed in the atmosphere or vacuum, the contact thermal resistance becomes a very large value. Also, the difference in contact thermal resistance from wafer to wafer is one factor that increases the error.

In addition, various wafer temperature measurement methods have been studied. The features and problems of the wafer temperature measurement method currently under study are described below.
(1) Method by Infrared Transmittance Measurement A silicon semiconductor is sharply transparent with respect to light having a wavelength near about 1.1 μm. Such a wavelength region in the absorption characteristic is called an absorption edge. Since the absorption edge changes depending on the temperature, the wafer temperature can be measured by observing the infrared transmittance and detecting the absorption edge. However, the wavelength of the absorption edge depends not only on the temperature, but also on other factors such as the concentration of impurities contained in the silicon semiconductor. Therefore, it is not very practical in a semiconductor manufacturing process through which silicon semiconductors having various impurity concentrations pass. Further, in a normal semiconductor manufacturing process, a resist film is applied on the wafer or other materials are deposited. If a film of another substance is attached to the wafer, an absorption edge is formed. Cannot be detected accurately.

(2) Method by reflectance measurement The reflectance of a substance changes with temperature. Therefore, the wafer temperature can be measured by irradiating the wafer with light having a known intensity, detecting the reflected light, and calculating the reflectance. Non-Patent Document 1 discloses a method of measuring temperature based on a change in silicon reflectance. However, such a wafer temperature measuring method has a problem that it is difficult to measure with high accuracy because the change in reflectance due to temperature is very small.

In order to improve such a problem, Patent Document 1 obtains a measurement step of measuring the reflectance of the surface of the temperature measurement object with respect to light having a plurality of wavelengths and a ratio of the reflectance measured in the measurement step. A temperature measurement method including a process and a process of specifying the temperature of the temperature measurement object based on the obtained reflectance is disclosed. In this case, it is disclosed that light having a wavelength of 430 nm to 800 nm is used (second page). However, even when light having a plurality of wavelengths is used, the change in reflectivity due to temperature is about 10 ⁻⁵ / ° C., and the temperature coefficient is still small, so it is difficult to improve accuracy.

(3) Method by spectral peak position measurement The peak position of the reflected light spectrum changes according to the temperature of the substance that is the reflector. In a silicon semiconductor, the peak of the reflected light spectrum appears at a wavelength in the ultraviolet region corresponding to the direct transition levels E1 and E2. Therefore, the wafer temperature can be measured by observing the spectrum of the reflected light and detecting the peak position. In this measurement method, since the polarization characteristic of ultraviolet light having high temperature dependence is used, precise temperature measurement is possible when the accuracy of the spectrum analyzer used is high. However, since such a spectrum analyzer is expensive, there is a problem that the cost increases.

  As a related technique, Patent Document 2 discloses that in a silicon device manufacturing process, a workpiece support and a beam of polarized light including ultraviolet light are irradiated onto the workpiece in order to control the temperature of the workpiece. A silicon workpiece having a light source, a spectrum analyzer for receiving the beam reflected from the workpiece, and a computer for receiving information representing the spectrum of the beam reflected from the spectrum analyzer and evaluating the temperature of the workpiece from the information An apparatus for processing is disclosed.

  Further, in Patent Document 3, in order to accurately measure the temperature of a silicon work peak in a wide range including a low temperature, (a) a step of providing a conversion system for converting spectral data into a temperature value, and light reflection In the step of measuring the temperature of the silicon workpiece using a mold thermometer, (i) a step of directing a polarized beam including ultraviolet rays toward the workpiece, (ii) the above using the spectrum analyzer Analyzing the spectrum of light reflected from the workpiece to obtain spectral data; (iii) converting the spectral data into a temperature value using the conversion system; and measuring the temperature of the silicon workpiece. A method is disclosed.

By the way, usually, an oxide film is naturally formed on the surface of the silicon wafer. In the semiconductor manufacturing process, oxide films having various thicknesses may be formed on the surface of a silicon wafer. However, when the wafer temperature is measured based on the reflected light from the wafer and the oxide film is formed on the surface of the wafer, the following problems occur. That is, by irradiating the wafer with light, light is reflected on the surface of the oxide film, or multiple reflections of light occur between the oxide film surface and the silicon surface, so that the reflection intensity changes due to light interference. . Reflection intensity fluctuations caused by such unwanted reflections are sensitive to the thickness of the oxide film and differ depending on the physical properties such as the type of wafer, so that the wafer temperature can be accurately measured. It will disappear.
Japanese Patent Application Laid-Open No. 2001-4442 JP 2000-2597 A JP 2000-356554 A J. Heller et al., “Temperature dependence of the silicon with surface oxide at wavelengths of 633 and 1047 nm”, Applied Physics Letters (Applied Physics Letters), July 1999, Vol. 75, No. 1, p. 43-45

  In view of the above, the present invention provides a non-contact type wafer temperature measurement method capable of accurately measuring a wafer temperature in situ even in a low temperature process, and a wafer temperature measurement using the same. An object is to provide an apparatus.

  In order to solve the above-described problem, a wafer temperature measuring method according to one aspect of the present invention includes a step (a) of generating light including a P-polarized component having a wavelength of 400 nm or less and irradiating a wafer as a temperature measurement target. Receiving the light reflected by the temperature measurement object, and detecting at least the intensity of the P-polarized component having a wavelength of 400 nm or less included in the reflected light, and the wavelength detected in step (b) (C) calculating the temperature of the temperature measurement object based on the intensity of the P-polarized light component of 400 nm or less.

  In addition, a wafer temperature measuring apparatus according to one aspect of the present invention includes a light irradiation unit that generates light including a P-polarized component having a wavelength of 400 nm or less and irradiates a wafer that is a temperature measurement object, and a temperature measurement object. A light receiving means for receiving the reflected light and detecting at least the intensity of the P-polarized component having a wavelength of 400 nm or less included in the reflected light, and the intensity of the P-polarized component having a wavelength detected by the light receiving means of 400 nm or less And calculating means for calculating the temperature of the temperature measurement object.

  According to the present invention, a P-polarized component having a wavelength of 400 nm or less is detected from the light reflected from the temperature measurement target, and the temperature of the measurement target is calculated based on the intensity. In the reflection intensity of the P-polarized component of this ultraviolet light, the dependence on temperature is very large compared to S-polarized light and visible light. Accordingly, it is possible to accurately measure the temperature of the measurement target without contact.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
First, the principle of the wafer temperature measuring method used in the wafer temperature measuring apparatus according to the first to ninth embodiments of the present invention will be described.

In the present invention, ultraviolet light containing a P-polarized component (light having a wavelength of 400 nm or less) is made incident on a wafer that is a temperature measurement target, and the reflected light reflected by the wafer is detected to measure the wafer temperature.
Here, an attempt has been made to measure the temperature based on the change in the reflection intensity of the silicon substrate, but generally only the longer wavelength side than the visible light is used as the detection light. However, GE Ellison et al., “Optical functions of silicon between 1.7 and 4.7 eV at elevated temperatures” (Physical Review B) , June 15, 1983, Vol. 27, No. 12), in the ultraviolet region including E1, which is a direct transition level of silicon, the dielectric function changes greatly depending on the temperature. It is known to show. Also, Sadao Adachi, “Model dielectric constants of Si and Ge” (Physical Review B), December 15, 1988, Vol. 38, Vol. 18) proposes a calculation model for the dielectric function of silicon.

  Accordingly, the inventors of the present application have sought a method for optically measuring temperature by paying attention to the characteristics of the silicon dielectric function in the ultraviolet region. At that time, when the calculation was performed using the calculation model by Adachi, it was found that the P-polarized component of the ultraviolet light showed a large temperature dependence as compared with the S-polarized component of the ultraviolet light and the visible light.

  FIG. 1 is a graph showing the rate of change in the reflection intensity of the P-polarized component with respect to silicon. The P-polarized component is incident on silicon at a predetermined temperature, and the wavelength component of the reflected light is analyzed using a spectroscope. It is obtained by doing. Here, the rate of change shown on the vertical axis in FIG. 1 indicates the intensity of the reflection spectrum after the temperature is raised by 10 ° C. when the intensity of the reflection spectrum before the temperature change is 1.

  As shown in FIG. 1, in the region where the wavelength is larger than 400 nm (visible region), the rate of change of the reflection intensity remains around 1.00, so the sensitivity of the reflection intensity to the temperature change of the sample (silicon) is very high. I can say no. On the other hand, in the ultraviolet region where the wavelength is shorter than 400 nm, since the rate of change is far from 1.00, it can be said that the reflection intensity changes significantly with respect to the temperature change of the sample. In particular, in the wavelength region where the change is large (the wavelength region where the rate of change is far from 1, and in the measurement range, around 360 nm to 370 nm and around 260 nm), the reflection intensity changes by 2% or more. Can be confirmed.

  FIG. 2 shows the reflectance of the S polarization component with respect to the silicon wafer, and FIG. 3 shows the reflectance of the P polarization component with respect to the silicon wafer. These graphs show the spectral intensities of the P-polarized component and S-polarized component at a given sample temperature using a model dielectric function (MDF) and the temperature characteristics of the parameters of the MDF measured by spectroscopic ellipsometry. It is obtained by seeking. 2 and 3, the solid line indicates the change in reflectance when the sample temperature is 20 ° C., the broken line indicates the change in reflectance when the sample temperature is 100 ° C., and the alternate long and short dash line is The change in reflectance when the sample temperature is 200 ° C. is shown.

  Here, the spectroscopic ellipsometry refers to the thickness and refractive index of the thin film based on the reflectance of the P-polarized component, the ratio of the absolute values of the reflectance of the S-polarized component, and the ratio of the phase changes thereof. It is a method of evaluating. Regarding MDF, Adachi, “Model Dielectric Function (MDF) Theory of Single Crystal Materials”, Surface Science, Vol. 18, No. 11, p. 669-675 (1997).

  As shown in FIG. 2, regarding the reflectance of the S-polarized light component, there is not much difference depending on the sample temperature in any wavelength region. On the other hand, as shown in FIG. 3, regarding the reflectance of the P-polarized component, a difference according to the sample temperature appears in the ultraviolet region. Particularly, in the region of 400 nm or less, the change in reflectance of the P-polarized component with respect to the sample temperature is large.

  Therefore, the inventors use the phenomenon that the reflection intensity of the P-polarized component of the ultraviolet light is sensitive to the temperature change of the sample, and irradiates the sample with light containing the P-polarized component of the ultraviolet light. Invented a method and apparatus for measuring the temperature of a sample by detecting the P-polarized component of reflected ultraviolet light.

In the first to ninth embodiments described below, it is desirable to use ultraviolet light including a wavelength corresponding to the direct transition level E1 or E2 in which the peak of the reflected light spectrum appears for temperature measurement. For example, in the case of silicon, a first peak appears at around 370 nm and a second peak appears at around 250 nm, so it is about 150 nm to 400 nm, preferably about 200 nm to 400 nm, and more preferably about 300 nm to 400 nm. UV rays are used. Accordingly, in the following embodiments, a light source device that generates ultraviolet light of about 150 nm to 400 nm, such as a high-pressure mercury lamp, a high-pressure mercury xenon lamp, an ultraviolet light-emitting diode (LED), or an ultraviolet laser diode (LD), Used depending on. As for the lower limit of the wavelength, as the wavelength of the ultraviolet light becomes shorter, deterioration of the light receiving side device becomes severe, and when the wavelength becomes 200 nm or less, ultraviolet light absorption by O ₂ occurs and the detection accuracy decreases. It is defined as a practical range.

  FIG. 4 is a schematic diagram showing the configuration of the wafer temperature measuring apparatus according to the first embodiment of the present invention. The wafer temperature measuring apparatus according to this embodiment uses the P-polarized component of ultraviolet light as the detection light, and uses the S-polarized component of ultraviolet light having the same wavelength as the detection light as the reference light, thereby adjusting the temperature of the wafer 100. It is a device to measure. Here, the reason why the S-polarized component is used as the reference light is that the reflected light of the S-polarized component has a relatively small temperature dependency, and thus the detection accuracy of the detection light (P-polarized component) is increased by using the reference light. Because.

  As shown in FIG. 4, the wafer temperature measuring apparatus according to the present embodiment includes a light source unit 110, prisms 121 and 122, a light receiving unit 130, a signal amplifier (AMP) 140, and a signal processing unit 150. Yes.

The light source unit 110 includes a drive circuit (DR) 111, a light source device (LS) 112, a collimator lens 113, a beam splitter 114, a polarizing element (polarizer) 115, an optical chopper 116, and a photodetector (PD). 117, and emits light to irradiate the wafer 100.
The drive circuit 111 controls the operation of the light source device 112. The light source device 112 is, for example, a light emitting diode (LED) that generates ultraviolet light having a wavelength near 365 nm. The LED is a light source device that generates non-polarized light.

The collimating lens 113 forms a parallel beam by transmitting the ultraviolet light emitted from the light source device 112. The beam splitter 114 guides the polarizing element 115 by transmitting a part of the incident light, and guides the remaining incident light to the photodetector 117 by reflecting the incident light.
The polarizing element 115 linearly polarizes by transmitting the ultraviolet light incident through the beam splitter 114. When a light source (for example, LD) that emits linearly polarized light is used as the light source device 112, the polarizing element 115 may be omitted.

  Here, in the present embodiment, the P-polarized component and the S-polarized component are used as detection light and reference light, respectively. Therefore, in the ultraviolet light after being reflected by the wafer 100, the intensity of the P-polarized component and the S-polarized component. It is desirable that the strength of the is approximately the same. However, the reflectance of the S-polarized component is larger than the reflectance of the P-polarized component, which is about 3 times. For this reason, it is desirable to adjust the polarization direction in advance so that the P-polarized component in the incident light with respect to the wafer 100 is increased. Specifically, the angle of the polarizing element 115 is adjusted so that the ratio of the P-polarized component and the S-polarized component in the incident light with respect to the wafer 100 is about 3: 1.

The optical chopper 116 controls the ultraviolet light emission timing from the light source unit 110 by chopping the ultraviolet light linearly polarized by the polarizing element 115 at a predetermined timing or frequency. Further, the optical chopper 116 outputs an on / off signal to the signal amplifier 140.
The photodetector 117 detects the intensity of the ultraviolet light reflected by the beam splitter 114. An output signal from the photodetector 117 is fed back to the drive circuit 111 and used for adjusting the amount of ultraviolet light emitted from the light source device 112.

Prism 121, by changing the direction of the ultraviolet light _{L I} emitted from the light source unit 110 to be incident ultraviolet light _{L I} the wafer 100. The prism 122, by changing the direction of the ultraviolet light _{L R} reflected by the wafer 100, guides the ultraviolet light _{L R} to the light receiving portion 130. As the prisms 121 and 122, total reflection prisms that totally reflect incident light in the prisms are used. This is to prevent changes in polarization state such as rotation of the polarization plane in the light linearly polarized by the polarizing element 115 and the light reflected from the wafer 100. The prisms 121 and 122 are adjusted in position and angle so that the light incident surface a and the light exit surface b are perpendicular to the optical axes of the incident light and the emitted light, respectively. Thereby, the polarization state of the incident light and the outgoing light to the prisms 121 and 122 is prevented from changing.

The light receiving unit 130 includes a wavelength selection filter 131, a polarization beam splitter 132, condenser lenses 133 and 135, and photodetectors (PD) 134 and 136, and receives light reflected by the wafer 100. .
The wavelength selection filter 131 is a filter that selectively transmits a wavelength component around 365 nm corresponding to the light source device 112. By providing a wavelength selection filter 131, is reflected by the wafer 100, the ultraviolet light L _R incident through the prism 122 is incident on the rear stage of the light receiving portion 130, it is possible to cut the other light, unnecessary light Mixing can be prevented and detection accuracy can be improved.

The polarization beam splitter 132 is, for example, a Glan laser prism or a Wollaston prism, and separates the ultraviolet light _LR into a P-polarized component and an S-polarized component by reflecting or transmitting incident light according to the polarization direction. In FIG. 4, the P-polarized component L _P is guided in the direction of the condenser lens 133 and the S-polarized component L _S is guided in the direction of the condenser lens 135 by the polarization beam splitter 132.

Condenser lens 133 condenses the P-polarized component _{L P} separated by the polarizing beam splitter 132 directs the optical detector 134. By providing the condenser lens 133, in a case where some variation in the position or direction of the optical path occurs also to minimize the effect of the variation, incident on the photodetector 134 to ensure the P-polarized component L _P Can be made.

Photodetector 134 includes, for example, a photoelectric conversion element such as a photodiode (PD), by detecting the light collected P-polarized light component (the detection light) L _P by the condenser lens 133, the intensity of light The electric signal according to is generated. This electrical signal is outputted from the light receiving unit 130 as a detection signal Y _1.

The condenser lens 135 condenses the S-polarized component L _S separated by the polarization beam splitter 132 and guides it to the photodetector 134. Similar to the condenser lens 133, the condenser lens 135 is also provided in order to reduce the influence of fluctuations in the optical path.
The photodetector 136 detects an S-polarized component (reference light) L _S collected by the condenser lens 135 to generate an electrical signal corresponding to the light intensity. This electrical signal is outputted from the light receiving unit 130 as a reference signal Y _2.

These light source 110, a prism 121 and 122, wafer 100, and, the light receiving unit 130, when the ultraviolet light _{L I} emitted from the light source unit 110 is incident on the wafer 100, and the incident angle is 35 ° to 85 ° about Thus, the positional and angular relationships are adjusted. Here, the incident angle is an angle formed by the normal of the reflecting surface of the wafer 100 and the incident light. The reason is that, as the incident angle becomes smaller, the difference in reflectance between the P-polarized component and the S-polarized component becomes smaller, so that the temperature measurement accuracy decreases. Conversely, when the incident angle is too large it would expect the width of the wafer 100 is greater than the width of the rays of ultraviolet light L _I, because vignetting (an unintended shade appears) is generated in the ultraviolet light L _I It is. Therefore, in the present embodiment, as a practical range, the incident angle is about 35 ° to 85 °, and more preferably about 60 ° to 75 °.

The signal amplifier 140 amplifies the detection signal Y ₁ and the reference signal Y ₂ output from the light receiving unit 130 and inputs them to the signal processing unit 150. In this case, the signal amplifier 140, by operating the lock-in based on the output ON / OFF signal from the optical chopper 116, that the signal based on the light other than the detection light L _P and the reference light L _S is mixed It is preventing. Note that when an optical signal other than the detection light L _P and the reference light L _S to the optical detector 134 and 136 there is no fear of contamination may not to lock-in operation to the signal amplifier 140. In that case, the optical chopper 116 is also unnecessary.

The signal processing unit 150 controls each unit of the wafer temperature measuring device, based on the detection signal Y ₁ and the reference signal Y _2, and calculates the temperature of the wafer 100. The signal processing unit 150 may be configured by a personal computer (PC), or may be configured by using a microcomputer chip, a digital multimeter, or the like.

  Next, a method for measuring the temperature of the wafer 100 will be described in detail with reference to FIGS. FIG. 5 is a block diagram for explaining the function of the signal processing unit 150 shown in FIG. 4, FIG. 6 is a flowchart showing a parameter calibration method, and FIG. 7 is a flowchart showing a temperature calculation method. is there.

  Here, in the present embodiment, the temperature of the wafer 100 is calculated by substituting a detection signal representing the intensity of the P-polarized component reflected from the wafer 100 into a predetermined function. For this purpose, the parameters of the function used are calibrated prior to the temperature calculation. This calibration may be performed every time the temperature of the wafer 100 is measured, or may be periodically performed.

The function f (Y) used for temperature calculation is a polynomial such as f (Y) = aY + b, f (Y) = aY ² + bY + c,. Such a function f (Y) is obtained by detecting the detection light and the reference light while measuring the temperature of the test wafer by the contact method in the temperature measuring apparatus shown in FIG. calculated using the ₁ and reference signal Y ₂ (e.g., regression analysis, etc.) obtained by performing. In the present embodiment, temperature measurement is performed using the function f (Y) = aY ² + bY + c.

  As shown in FIG. 5, the signal processing unit 150 includes a calibration controller 11, a wafer temperature instruction unit 12, a calibration data storage unit 13, a calibration value calculation unit 14, a calibration parameter storage unit 15, and a relative value calculation unit. 21, a temperature calculation unit 22, and a temperature signal output unit 23. In FIG. 5, the broken line indicates the flow of operation during parameter calibration, and the solid line indicates the flow of information during temperature measurement.

When calibrating parameters, first, in step S11 of FIG. 6, a test wafer (wafer with temperature sensor) provided with a temperature sensor is set on the stage of the temperature measurement apparatus.
Next, in step S12, the calibration controller 11 (FIG. 5) sets the calibration temperature T _S to 0 ° C. Accordingly, the wafer temperature instruction unit 12 sets the stage temperature of the temperature measuring device to T _S (= 0 ° C.) in step S13.

Next, in step S14, the measurement and the temperature T of the temperature sensor with the wafer, and intensity I _P of the P-polarized component L _P reflected from the wafer, and the intensity I _S of the S-polarized component L _S. The temperature T of the wafer with the temperature sensor is stored in the calibration data storage unit 13. A detection signal Y ₁ representing the intensity I _P of the P-polarized component detected by the photodetector 134 is amplified by the signal amplifier 140 and input to the relative value calculation unit 21. On the other hand, the reference signal Y ₂ representing the intensity I _S of the S-polarized component detected by the photodetector 136 is amplified by the signal amplifier 140 and input to the relative value calculator 21. The relative value calculation unit 21 calculates the detection signal Y ₁ , the reference signal Y _2, and the relative value Y = Y ₁ / Y ₂ and stores them in the calibration data storage unit 13. The relative value Y represents the relative value of the intensity I _S of the intensity I _P and S-polarized component of the P-polarized light component.

Next, in step S15, the calibration controller 11 calculates the temperature was increased 20 ° C. The calibration temperature _{T S.} When calibration temperature T _S obtained is less than 200 ° C., in step S16, again, setting the stage temperature, as well as, a temperature sensor with a wafer temperature T, the intensity I _P of the P-polarized _component, and The measurement of the intensity I _S of the S-polarized component is repeated (steps S13 to S16). On the other hand, if the calibration temperature T _S is equal to or higher than 200 ° C., the calibration controller 11, terminate these measurements, to start calculation of the calibration value of the parameter (step S17).

In step S < _b > 17, the calibration value calculation unit 14 acquires the temperatures T of the plurality of wafers stored in the calibration data storage unit 13 and the relative values Y (= Y ₁ / Y ₂ ) corresponding thereto, and these values. Is substituted into the function T = f (Y) = aY ² + bY + c to create a plurality of equations. Then, parameters a, b, and c are obtained by the least square method using those equations. These calibrated parameters are stored in the calibration parameter storage unit 15.

When measuring the temperature of the wafer, first, in step S21 of FIG. 7, the intensity _{I P} of the reflected P-polarized component _{L P} from the wafer 100 (FIG. 4), the intensity _{I P} of S-polarized component _{L S} Is measured. The detection signal Y ₁ representing the intensity I _P of the P-polarized component is amplified by the signal amplifier 140 and input to the relative value calculation unit 21. The reference signal Y ₂ representing the intensity I _S of the S-polarized component is amplified by the signal amplifier 140 and input to the relative value calculation unit 21.

Next, in step S22, the relative value calculating section 21 calculates a relative value _{Y (= Y 1 / Y 2} ) between the intensity _{I S} of the intensity _{I P} and S-polarized component of the P-polarized light component. In step S23, the temperature calculation unit 22 acquires the calibrated parameters a, b, and c from the calibration parameter storage unit 15, and the function T = f (Y) = aY ² + bY + c is calculated by the relative value calculation unit 21. The temperature T of the wafer 100 is calculated using the relative value Y.

In step S24, the temperature signal output unit 23 displays the temperature T by outputting a signal representing the calculated temperature T to a monitor or the like. When the temperature measurement is further continued (step S25), the P-polarized component intensity _IP and the S-polarized component intensity _IS are measured again.

In the above description, the simple ratio Y ₁ / Y ₂ between the detection signal Y ₁ and the reference signal Y ₂ is used as the relative value Y, but the ratio of the values after taking the offset (Y ₁ -α). / (Y ₂ −α) may be used. Further, the relative value may be obtained by using an appropriate function. For example, the relative value Y may be obtained by Y = (aY ₁ ² + bY ₁ + c) / (aY ₂ ² + bY ₂ + c).

Further, instead of calculating the temperature using a relative value Y of the detection signal _{Y 1} and the reference signal _{Y 2,} using the function to a detection signal _{Y 1} and _the reference signal _{Y 2} and the variable _{g (Y} 1, _{Y 2)} Thus, the temperature may be calculated directly. This function g (Y ₁ , Y ₂ ) and its parameters can also be obtained by using the measured value of the temperature obtained by the contact method, as in the case of the function f (Y).

In the present embodiment described above, the detection light (P-polarized component L _P ) and the reference light (S-polarized component L _S ) take the same optical path until they enter the light receiving unit 130. Therefore, the influence of the fluctuation of the optical path due to the tilt of the wafer 100 that is the temperature measurement object, the thermal disturbance of the gas in the optical path, and the like are the same in the detection light and the reference light until immediately before separation. Accordingly, there is an advantage that such influence can be canceled by taking a relative value (for example, a ratio between the two) of the detection light and the reference light. Thereby, temperature measurement can be performed with higher accuracy than other methods (for example, a method using a reflectance which is a ratio of incident light to the wafer 100 and reflected light).

In the present embodiment, when the wafer temperature is simply measured, only the intensity of the detection light (P-polarized component) may be used. In this case, the detection signal Y ₁ output from the optical detector 134 of the receiving portion 130 shown in FIG. 4, may be converted to temperature by using a predetermined equation. As described above, since the reflection intensity of the P-polarized component of the ultraviolet light is sensitive to the temperature change of the sample, it is possible to measure the wafer temperature without using the reference light.

  Next, a wafer temperature measuring apparatus according to the second embodiment of the present invention will be described. FIG. 8 is a schematic diagram showing the configuration of the wafer temperature measuring apparatus according to the present embodiment. In the present embodiment, the temperature of the wafer 100 is measured by using a P-polarized component of ultraviolet light as detection light and using an S-polarized component having a wavelength different from that of the detection light as reference light. As reference light, it is desirable to use visible light having a relatively low temperature dependency of reflection intensity.

  As shown in FIG. 8, the wafer temperature measuring apparatus according to this embodiment includes a light source unit 210, prisms 121 and 122, a light receiving unit 230, a signal amplifier 140, and a signal processing unit 150. The configurations and operations of the prisms 121 and 122, the signal amplifier 140, and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

The light source unit 210 includes driving circuits (DR) 211 and 216, light source devices (LS) 212 and 217, collimating lenses 213 and 218, beam splitters 214 and 219, photodetectors (PD) 215 and 220, A polarization beam splitter 221, an optical chopper 222, and a light amount comparison unit (CMP) 223 are included.
The drive circuit 211 controls the operation of the light source device 212. The light source device 212 is, for example, an LD that generates ultraviolet light having a wavelength near 365 nm. The LD emits linearly polarized light.

The collimating lens 213 forms a parallel beam by transmitting the ultraviolet light L _UV emitted from the light source device 212. The beam splitter 214 transmits a part of the incident light to guide the polarization beam splitter 221 and reflects the remaining incident light to the photodetector 215. An output signal from the photodetector 215 is fed back to the drive circuit 211 and used for adjusting the amount of ultraviolet light emitted from the light source device 212.

On the other hand, the drive circuit 216 controls the operation of the light source device 217. The light source device 217 is a light source device that emits light having a wavelength different from that of the light emitted from the light source device 212. The light emitted from the light source device 217 may be ultraviolet light or visible light. In this embodiment, LD wavelength emits a visible light _{L VS} around 650nm is used.

Collimator lens 218, by transmitting the light L _VS outputted from the light source 217 to form a parallel beam. The beam splitter 219 guides the incident light to the polarization beam splitter 221 by transmitting a part of the incident light, and reflects the remaining incident light to the photodetector 220. The output signal from the light detector 220 is fed back to the drive circuit 216 and used to adjust the amount of light emitted from the light source device 217.

The polarization beam splitter 221 transmits the incident P-polarized component as it is and reflects the S-polarized component to change the optical path.
Here, in the present embodiment, the P-polarized component of the ultraviolet light L _UV emitted from the light source device 212 is used as detection light, and the S-polarized component of the visible light L _VS emitted from the light source device 217 is used as reference light. . Therefore, in the optical system in the light source unit 210, the ultraviolet light L _UV is incident on the polarizing beam splitter 221 in a P-polarized state, and the visible light L _VS is incident on the polarizing beam splitter 221 in an S-polarized state. Thus, the position and angle are adjusted. As a result, a light beam in which the P-polarized component of ultraviolet light and the S-polarized component of visible light are mixed is formed and guided in the direction of the light chopper 222.

  The optical chopper 222 controls the light emission timing from the light source unit 210 by chopping the light beam formed by the polarization beam splitter 221 at a predetermined timing or frequency. The on / off signal output from the optical chopper 222 is input to the signal amplifier 140 and used for the lock-in operation in the signal amplifier 140.

  The light quantity comparison unit 223 obtains the light quantity ratio of the light emitted from the light source devices 212 and 217 based on the output signals from the photodetectors 215 and 220 and outputs a signal representing the light quantity ratio to the signal processing unit 150. . This signal representing the light quantity ratio is used when correcting the calculated wafer temperature.

Here, the light source unit 210, the prisms 121 and 122, the wafer 100, and the light receiving unit 230 are incident on the wafer 100 in a state where the ultraviolet light L _UV included in the light beam emitted from the light source unit 210 is P-polarized. The position and angle are adjusted so that the visible light L _VS is incident on the wafer 100 in the S-polarized state. Further, the incident angle to the wafer 100 is desirably set to 35 ° to 85 °, as described in the first embodiment.

The light receiving unit 230 includes a polarizing beam splitter 231, wavelength selection filters 232 and 235, condenser lenses 233 and 236, and photodetectors (PD) 234 and 237.
Polarization beam splitter 231, the reflected light L _R incident on the light receiving unit from the wafer 100 through the prism 122, by reflection or transmission in accordance with the polarization direction, is separated into a P-polarized component and S-polarized light component. The P-polarized component L _UVP of the ultraviolet light separated by the polarizing beam splitter 231 is guided in the direction of the wavelength selective filter 232 by passing through the wavelength selective filter 232, and the S-polarized component L _VSS of the visible light is converted into the wavelength selective filter. The light is reflected by 232 and guided in the direction of the wavelength selection filter 235.

The wavelength selection filter 232 is a filter that selectively transmits a wavelength component around 365 nm corresponding to the light source device 212. The wavelength selection filter 232 is provided to prevent unnecessary disturbance light from being mixed into the subsequent stage. The condenser lens 233 collects the P-polarized light component L _UVP of the ultraviolet light that has passed through the wavelength selection filter 232 and guides it to the photodetector 234. The photodetector 234 detects the P-polarized component L _UVP , generates an electrical signal (detection signal Y ₁ ) corresponding to the light intensity, and outputs it.

On the other hand, the wavelength selection filter 235 is a filter that selectively transmits a wavelength component near 650 nm corresponding to the light source device 217. The condensing lens 236 collects the S-polarized light component L _VSS of visible light that has passed through the wavelength selection filter 234 and guides it to the photodetector 237. The photodetector 237 detects this S-polarized component L _VSS and generates and outputs an electrical signal (reference signal Y ₂ ) corresponding to the light intensity.

In the signal processing unit 150, the temperature of the wafer 100 is calculated based on the detection signal Y ₁ and the reference signal Y ₂ input via the signal amplifier 140. This calculation method is the same as that described in the first embodiment. At that time, the signal intensities of the detection signal Y ₁ and the reference signal Y ₂ are corrected based on the signal indicating the light amount ratio output from the light amount comparison unit 223 of the light source unit 210.

In the present embodiment described above, when the lights L _UV and L _VS having different wavelengths are mixed, and the reflected light from the wafer 100 is separated into the P-polarized component L _UVP and the S-polarized component L _VSS. In addition, although the polarization beam splitter is used, other optical elements or optical devices may be used. For example, instead of the polarizing beam splitter 221 shown in FIG. 8, a dichroic mirror that reflects or transmits light according to the wavelength may be used. In this case, the polarization direction with respect to the dichroic mirror of the visible light L _VS emitted from the light source 217 may not be the S-polarized light.

In this embodiment, since the light emitted from the different light source devices 212 and 217 is once mixed, the detection light L _UVP and the reference light L _VSS are the same optical path until they are separated by the polarization beam splitter 231 of the light receiving unit 230. Pass through. Therefore, by taking the relative value of the detection light and the reference light, the influence of fluctuations in the optical path can be canceled, so that it is possible to perform highly accurate temperature measurement.

  Next, a wafer temperature measuring apparatus according to the third embodiment of the present invention will be described. FIG. 9 is a schematic diagram showing the configuration of the wafer temperature measuring apparatus according to the present embodiment. This wafer temperature measurement apparatus is an apparatus that measures the temperature of the wafer 100 by using a P-polarized component of ultraviolet light as detection light and an S-polarized component of ultraviolet light having the same wavelength as the detection light as reference light. .

  As shown in FIG. 9, the wafer temperature measuring apparatus according to this embodiment includes a light source unit 310, a chamber 320, a light receiving unit 330, a signal amplifier 140, a signal processing unit 150, a support unit 340, and a mechanical stage. 341, an autocollimator 342, and a mechanical stage driving unit 343 are included. The configurations and operations of the signal amplifier 140 and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

The light source unit 310 includes a drive circuit (DR) 311, a light source device (LS) 312, a collimator lens 313, and a wavelength selection filter 314.
The drive circuit 311 controls the operation of the light source device 312. The light source device 312 is, for example, a high-pressure mercury lamp or a mercury xenon lamp that generates ultraviolet light including a wavelength component near 365 nm that is a mercury emission line. Alternatively, an LED that generates ultraviolet light having a wavelength near 375 nm may be used. These light sources generate unpolarized light.

  Alternatively, the light source device 312 may be a light source that generates polarized light, such as an ultraviolet laser. In that case, the ratio of the P-polarized component and the S-polarized component in the incident light on the wafer 100 is about 3 to 1 so that the P-polarized component and the S-polarized component are approximately the same in the reflected light from the wafer 100. It is desirable to adjust the polarization direction so that

  The collimating lens 313 forms a parallel beam by transmitting the ultraviolet light emitted from the light source device 312. The wavelength selection filter 314 is a band-pass filter that cuts out and transmits a wavelength component near 365 nm with respect to the parallel beam transmitted through the collimator lens 313.

  Heaters 322 and 323 are provided in the chamber 320 for maintaining the wafer 100 at a predetermined temperature in the semiconductor manufacturing process. The light used to measure the wafer temperature is introduced into the chamber 320 through the window 321, passes through the optical path passages 31 and 34 formed in the heaters 322 and 323, and passes through the window 324. It is led out of the chamber 320.

The optical path passage 31 provided in the heater 322 is formed by forming holes in the heater 322 and arranging windows 32 and 33 at both ends thereof. Similarly, the optical path passage 34 in the heater 323 is formed by forming holes in the heater 323 and disposing windows 35 and 36 at both ends thereof. These windows 32,33,35,36 and, windows 321 and 326 of the chamber 320 is arranged perpendicular or substantially perpendicular to the incident light _{L UV} and the reflected light _{L R} passing therethrough . The reason for this is that if even a small amount of impurities adhere to the boundary surface such as a window or the temperature changes, the transmittance of the light passing therethrough will change, but the light will pass through the boundary surface. This is because the ratio of the P-polarized light component and the S-polarized light component is maintained as long as is incident perpendicularly.
Further, impurity adhesion preventing covers 325 and 326 are provided between the window 321 and the window 32 and between the window 36 and the window 324, respectively.

The light receiving unit 330 includes a Wollaston prism 331, integrating spheres 332 and 335, photodetectors (PD) 333 and 336, a beam splitter 334, and a position detection sensor 337.
Wollaston prism 331 is a polarizing prism for splitting the linearly polarized light orthogonal vertically, the reflected light L _R from the wafer 100 is separated into a P-polarized component L _P and S-polarized component L _S, an integrating sphere 332 and Each is guided in the direction of the beam splitter 334.

  The integrating spheres 332 and 335 are hollow spheres having openings for incident light, detectors, and the like, and a material that diffuses light is applied to the entire inner surface. Photodetectors 333 and 336 are respectively disposed in the detector openings of the integrating spheres 332 and 335, and the light incident on the integrating sphere is detected by the photodetectors 333 and 336 regardless of the direction of incidence. Led to the face.

  The reason for using such integrating spheres 332 and 335 is as follows. For example, fluctuations may occur in the optical path from the wafer 100 to the photodetectors 333 and 336 due to the influence of thermal expansion due to temperature changes. In such a case, if the incident light is misaligned with respect to the detection surface of the photodetector, the light detection intensity may change due to non-uniformity of light sensitivity on the detection surface. . If such a change is equal between the detection light (P-polarized component) and the reference light (S-polarized component), the error can be canceled by taking the ratio between them. However, when such a change occurs after the detection light and the reference light are separated by the Wollaston prism 331, a difference in the change appears in the temperature measurement accuracy. For this reason, in this embodiment, the integrating spheres 332 and 335 are arranged in front of the photodetectors 333 and 336, thereby minimizing the influence of the variation in the optical path.

P-polarized component L _P of ultraviolet light separated by the Wollaston prism 331 through the integrating sphere 332 and enters the optical detector 333. Photodetector 333 detects the incident light to output an electric signal corresponding to the intensity of light as a detection signal Y _1.

The S-polarized component L _S of the ultraviolet light separated by the Wollaston prism 331 is separated in two directions by the beam splitter 334. One separated S-polarized component L _S enters the photodetector 336 via the integrating sphere 335. Photodetector 336 detects the intensity of the incident light and outputs an electrical signal corresponding to the intensity of light as a reference signal Y _2. The other S-polarized light component separated by the beam splitter 334 enters the position detection sensor 337. The position detection sensor 337 detects a positional shift of the incident light based on the incident light and outputs a detection signal. The signal processing unit 150 calculates the temperature of the wafer 100 based on the detection signal Y ₁ and the reference signal Y ₂ input via the signal amplifier 140, and based on the detection signal output from the position detection sensor 337. A positional deviation of the relative position between the wafer 100 and the light receiving unit 330 is calculated, and a correction amount of the position of the light receiving unit 330 is further obtained.

  The support part 340 is formed of a material having a very small thermal expansion coefficient, such as invar (low expansion alloy) or polycrystalline glass, and maintains the positional relationship between the light source part 310 and the light receiving part 330. I support it. The support unit 340 includes a mechanical stage 341, an autocollimator unit 342, and a mechanical stage drive unit (MTD) 343.

The mechanical stage 341 adjusts the position of the support portion 340 in the vertical direction (distance direction with respect to the wafer 100) and the angle of the two axes in the tilt direction. Thereby, the position and angle of the ultraviolet light L _UV that is emitted from the light source unit 310 is incident on the wafer 100, as well as the position and angle of the reflected light L _R received by the light receiving unit 330 is adjusted from the wafer 100 is reflected The

  The autocollimator unit 342 irradiates the wafer 100 with light through a window 327 provided in the chamber 320, detects the position and angle of the light reflected by the wafer 100, and outputs a detection signal to the signal processing unit 150. To do. Based on this detection signal, the signal processing unit 150 calculates the deviation of the position and angle of the support unit 340 with respect to the wafer 100 and further obtains the correction amount of the support unit 340.

  The mechanical stage drive unit 343 controls the mechanical stage 341 based on the correction amount calculated based on the detection signal of the autocollimator unit 342 and the correction amount calculated based on the detection signal of the position detection sensor 337. Thus, alignment of the light source unit 310 and the light receiving unit 330 with the wafer 100 is performed.

  In the present embodiment described above, non-polarized light is incident on the wafer 100 by using a high-pressure mercury lamp or the like as the light source device 312. However, polarized light may be incident on the wafer 100 by inserting a polarizing element in the light source unit 310 or in the front stage of the chamber 320. In that case, as described above, the P-polarized component and the S-polarized component in the incident light with respect to the wafer 100 are set so that the P-polarized component and the S-polarized component in the reflected light from the wafer 100 are approximately the same. The angle of the polarization element to be inserted is adjusted so that the ratio of the polarization element becomes about 3 to 1.

  FIG. 10 is a diagram for explaining a modified example of the wafer temperature measuring apparatus according to the third embodiment of the present invention. In the wafer temperature measuring apparatus shown in FIG. 9, instead of the optical path passage including the entrance window 32 to the exit window 33 and the entrance window 35 to the exit window 36 shown in FIG. A rod 350 formed with may be disposed. The rod 350 is made of a material that transmits ultraviolet rays, such as quartz. By using such a rod 350, impurities can adhere to the middle of the optical path (for example, both end faces of the window 32), and environmental changes in the optical path (for example, thermal disturbance of gas, etc.) can be suppressed. It is possible to prevent the ratio of the P-polarized component and the S-polarized component contained in the ultraviolet light passing therethrough from changing.

  Next, a wafer temperature measuring apparatus according to the fourth embodiment of the present invention will be described. FIG. 11 is a schematic diagram showing the configuration of the wafer temperature measuring apparatus according to the present embodiment. This wafer temperature measuring apparatus uses ultraviolet light including a P-polarized component as detection light, uses ultraviolet light including an S-polarized component as reference light, and is identical in incident light to the wafer 100 and reflected light from the wafer 100. It is characterized by taking an optical path.

  As shown in FIG. 11, the wafer temperature measuring apparatus according to this embodiment includes a drive circuit (DR) 401, a light source device (LS) 402, a collimator lens 403, an aperture (opening) 404, and a spectroscopic unit 405. A reflection element 406, a light modulator 407, a polarizing element 408, a condenser lens 409, an integrating sphere 410, a photodetector (PD) 411, a light modulator driver (PCD) 412, a signal An amplifier 140 and a signal processing unit 150 are included. The operations of the signal amplifier 140 and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

  The drive circuit 401 controls the light source device 402. The light source device 402 is, for example, a high-pressure mercury lamp or a mercury xenon lamp that generates ultraviolet light including a wavelength component near 365 nm that is a mercury emission line. Alternatively, as the light source device 402, an LED that generates ultraviolet light having a wavelength of around 375 nm may be used. These light source devices are light sources that generate non-polarized light. However, polarized light may be emitted by providing a polarizing element after the light source device 402, or a light source device that generates polarized light may be used. Anyway. In these cases, as described in the third embodiment, it is necessary to adjust the polarization direction so that the P-polarized component and the S-polarized component have a predetermined ratio in the incident light on the wafer 100. .

  The collimating lens 403 forms a parallel beam by transmitting the ultraviolet light emitted from the light source device 402. The aperture 404 forms a beam having a predetermined diameter by allowing the parallel beam to pass therethrough.

  The spectroscopic unit 405 includes a plurality of beam splitters 41 to 43 that are formed of the same material and are placed close to each other so as to be thermally placed in the same environment. Each of the beam splitters 41 to 43 passes light incident from the first direction in the second direction, and reflects reflected light returning from the second direction in a third direction different from the first direction. To pass through. The beam splitter 41 and the beam splitter 42 are arranged so as to make an angle of 90 ° with the optical axis as the rotation axis, and the beam splitter 42 and the beam splitter 43 have an angle of 90 ° with the optical axis as the rotation axis. It is arranged to do. When the light emitted from the light source device 402 and passed through the collimator lens 403 and the aperture 404 is introduced into such a spectroscopic unit 405, the light passes through the beam splitters 41 and 42 and is guided toward the wafer 100. In addition, the return light from the wafer 100 is reflected by the beam splitters 42 and 43 and guided toward the optical modulator 407.

  The advantage of arranging the plurality of beam splitters 41 to 43 in this way is as follows. In general, since an optical element such as a beam splitter has polarization dependence, the polarization state (ratio between the P-polarized component and the S-polarized component) is reflected in the reflected or transmitted light by reflecting or transmitting the light. It will change. Therefore, in the present embodiment, changes in the polarization state are prevented based on the following principle.

Assuming that the transmittance of the P-polarized component in the beam splitter 41 is T _P and the transmittance T _S of the S-polarized component, the transmittance T of the P-polarized component in the beam splitter 42 arranged to be rotated by 90 ° relative thereto. The transmittances T _S ′ of _P ′ and S polarization components are T _P ′ = T _S and T _S ′ = T _P.

Further, if the intensity of the P-polarized component of the light incident on the beam splitter 41 is I _P , and the intensity of the S-polarized component is I _S , the intensity of these polarized components is transmitted through the beam splitter 41, so that I _P × It changes to T _P (P polarization component), I _S × T _S (S polarization component). When such light is further transmitted through the beam splitter 42, the intensity of the light after transmission changes as follows.
P-polarized light _{component: I P × T P × T} P '= I P × T P × T S
S-polarized light _{component: I S × T S × T} S '= I S × T S × T P
After all, the ratio of the P-polarized component and the S-polarized component does not change before entering the beam splitter 41 and after passing through the beam splitter 42.

Further, assuming that the reflectance of the P-polarized component of the beam splitter 42 is R _P , and the reflectance of the S-polarized component is R _S , the reflection of the P-polarized component is reflected in the beam splitter 43 arranged by being rotated by 90 °. The rate R _P ′ and the reflectance R _S ′ of the S polarization component are R _P ′ = R _S and R _S ′ = R _P. Therefore, the return light from the wafer 100 changes as follows by being reflected from the beam splitters 42 and 43. Here, it is assumed that the intensity of the P polarization component in the return light from the wafer 100 is I _P ′, and the intensity of the S polarization component is I _S ′.
P polarization component: I _P '× R _P × R _P ' = I _P '× R _P × R _S
S-polarized component: I _S '× R _S × R _S ' = I _S '× R _S × R _P
Again, the ratio of the P-polarized component and the S-polarized component does not change before entering the beam splitter 42 and after being reflected by the beam splitter 43.
Furthermore, by placing the beam splitters 41 to 43 close to each other in the same thermal environment, their polarization dependency is made uniform, so that the change in the polarization state is effectively suppressed.

  The reflection element 406 is incident on the wafer 100 from the direction of the spectroscopic unit 405, and further reflects the light reflected by the wafer 100 to make it incident on the wafer 100 again. As the reflection element 406, a total reflection mirror, a right-angle prism, a corner cube prism, or the like is used. Among them, the corner cube prism uses the total internal reflection of three orthogonal surfaces, so that the incident light can be folded back 180 ° in the incident direction regardless of the incident direction. This is desirable because it can cope with the change in the incident angle caused by.

  The optical modulator 407 is formed by, for example, a Pockels cell, and changes the polarization direction of the light transmitted therethrough according to the supplied electric signal. Here, the Pockels cell is an optical element using an EO effect (electro optic effect) in which the refractive index and anisotropy of the crystal change when an electric field is applied to the crystal. By controlling the electric field applied to the Pockels cell, the polarization plane of the light passing through it can be rotated by a desired angle (eg, 90 °). The operation of the optical modulator 407 is controlled by an electrical signal supplied from the optical modulator driver 413.

The polarizing element 408 transmits a predetermined polarization component included in the light transmitted through the light modulator 406. In the present embodiment, the polarizing element 408 transmits a component incident on the polarizing element 408 as P-polarized light.
The condensing lens 409 condenses the light transmitted through the polarizing element 408 and makes it incident on the integrating sphere 410. The integrating sphere 410 guides the incident light to the detection surface of the photodetector 411. These condensing lens 409 and integrating sphere 410 are provided in order to suppress changes in the intensity of the detection signal due to an optical path change due to temperature or the like. Furthermore, the photodetector 411 detects incident light and outputs an electrical signal corresponding to the intensity of the light.

The optical modulator driving unit 412 generates an electrical signal for activating the optical modulator 407 at a predetermined interval under the control of the signal processing unit 150 and supplies the electrical signal to the optical modulator 407.
When the light modulator 407 is in an inactive state, the light reflected from the wafer 100 and incident on the light modulator 407 via the spectroscopic unit 405 passes through the light modulator 407 as it is without changing the polarization direction. To do. As a result, the P-polarized component contained in the reflected light from the wafer 100 passes through the polarizing element 408. On the other hand, when the light modulator 407 is activated, the reflected light from the wafer 100 is rotated by 90 ° in the polarization direction by the light modulator 407. As a result, the P-polarized component after the rotation of the polarization direction (that is, the S-polarized component included in the reflected light from the wafer 100) is transmitted through the polarizing element 408. In this way, by switching the active state of the light modulator 407, the P-polarized component and the S-polarized component included in the reflected light from the wafer 100 are passed through the condenser lens 409 and the integrating sphere 410 to the signal detector 411. Are detected alternately. Thereby, a signal representing the P-polarized component (detection signal Y ₁ ) and a signal representing the S-polarized component (reference signal Y ₂ ) are input to the signal processing unit 150 in a time division manner.

The signal processing unit 150 takes in the detection signal from the signal amplifier 140 in synchronization with the signal generation timing by the optical modulator driving unit 412. Then, a signal detected when the optical modulator 407 is in an inactive state (detection signal Y ₁ ), and a signal detected when the optical modulator 407 is activated (referred to as a reference signal Y ₂ ) Based on the above, the temperature of the wafer 100 is calculated. The temperature calculation method is the same as that described in the first embodiment.

  As described above, according to the present embodiment, the wafer temperature is measured based on the reflected light reflected twice by the wafer 100, so that it is twice as much as the case where the reflected light reflected once is used. Sensitivity can be obtained. In addition, since the detection light and the reference light take the same optical path from the light emitted from the light source device 402 until they are detected by the photodetector 411, errors caused by fluctuations in the optical path can be canceled with high accuracy. . Note that the wafer temperature may be measured based on the reflected light reflected three or more times by the wafer 100 by further providing an optical system such as the reflecting prism 406.

Next, a wafer temperature measuring apparatus according to the fifth embodiment of the present invention will be described.
Here, the wafer temperature measuring apparatus according to the fifth to eighth embodiments described below is a low temperature process regardless of the surface state of the temperature measurement target (for example, when an oxide film is formed on a silicon wafer). Is used to accurately measure the wafer temperature in situ.

  As described above with reference to FIGS. 1 to 3, the inventors of the present application irradiate the sample with light including a P-polarized component of ultraviolet light and apply the P-polarized component of ultraviolet light reflected from the sample. When examining the measurement of the temperature of the sample by detection, it was also confirmed that the reflection intensity of the P-polarized component of the ultraviolet light is greatly influenced by the surface state of the temperature measurement object. Specifically, the formation of an oxide film on the silicon surface causes multiple reflections of light between the oxide film surface and the silicon surface, so that the reflection intensity varies greatly depending on the thickness of the oxide film. . In addition, since the physical properties of the oxide film vary depending on the type of temperature measurement object, the fluctuation is not uniform.

Therefore, in order to accurately calculate the temperature of the measurement target, the inventors of the present application are not significantly affected by the reflection intensity A _UVP of the P-polarized component of the ultraviolet light sensitive to the temperature change of the measurement target and the temperature change. _Pay attention to A _UVP / A _S1 which is the ratio with the polarization component A _S1 and A _VSP / A _S2 which is the ratio between the P-polarization component A _{VSP of} visible light and the S-polarization component A _S2 which are not affected by temperature change. did. The ratio A _UVP / A _S1 is a function of the temperature to be measured and the surface state (thickness of the oxide film), but the ratio A _VSP / A _S2 is almost a function of only the surface state. By using this, it is possible to eliminate the influence of the surface state of the wafer on the temperature measurement.

  FIG. 12 is a schematic diagram showing a configuration of a wafer temperature measuring apparatus according to the fifth embodiment of the present invention. As shown in FIG. 12, the wafer temperature measuring apparatus according to this embodiment includes a light source unit 510, prisms 121 and 122, a light receiving unit 530, a signal amplifier (AMP) 140, and a signal processing unit 150. Yes. The apparatus configurations of the prisms 121 and 122, the signal amplifier 140, and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

  The light source unit 510 includes drive circuits (DR) 511 and 514, light source devices (LS) 512 and 515, collimating lenses 513 and 516, a wavelength synthesizing element 517, a polarizing element (polarizer) 518, and an optical chopper 519. And emits light for irradiating the wafer 100.

The drive circuits 511 and 514 control the operations of the light source devices 512 and 515, respectively.
The light source device 512 is, for example, a light emitting diode (LED) that generates ultraviolet light (light having a wavelength of 400 nm or less) L _UV having a wavelength of around 365 nm. The light source device 515 is, for example, a light emitting diode that generates visible light (light having a wavelength greater than 400 nm) L _VS having a wavelength near 650 nm.

The collimating lens 513 forms a parallel beam by transmitting the ultraviolet light L _UV emitted from the light source device 512. The collimating lens 516 forms a parallel beam by transmitting the visible light L _VS emitted from the light source device 515.
Wavelength combining element 517, for example, it is constituted by a dichroic mirror which reflects only a predetermined wavelength component, and guides the direction of the polarizing element 518 by reflecting the ultraviolet light L _UV propagated from the direction of the light source 512, The visible light L _VS propagated from the direction of the light source device 515 is transmitted and guided in the direction of the polarizing element 518.

The polarizing element 518 linearly polarizes the light incident through the wavelength combining element 517 by transmitting the light.
Here, in the reflected light from the wafer 100, in order to make the intensity of the P-polarized component and the intensity of the S-polarized component approximately the same, the polarization direction so that the P-polarized component in the incident light on the wafer 100 is larger. It is desirable to adjust in advance. Therefore, in the present embodiment, the angle of the polarizing element 518 is adjusted so that the ratio of the P-polarized component and the S-polarized component in the incident light on the wafer 100 is about 3: 1.

  Note that when the light source devices 512 and 515, such as laser diodes (LD), that emit pre-polarized light are used, the polarizing element 518 is not necessary. In that case, it is necessary to adjust the arrangement of the light source devices 512 and 515 so that light is incident on the wafer 100 in an appropriate polarization state.

  The optical chopper 519 controls the timing at which the light from the light source unit 510 is emitted by chopping the ultraviolet light linearly polarized by the polarizing element 518 at a predetermined timing or frequency. Further, the optical chopper 519 outputs an on / off signal to the signal amplifier 140.

The light receiving unit 530 includes a polarizing beam splitter (polarizing prism) 531, condenser lenses 532 and 535, integrating spheres 533 and 536, and photodetectors (PD) 534 and 537, and is reflected by the wafer 100. The received light _LR is received.
Polarization beam splitter 531, the light L _R that is incident thereon and separated according to polarization direction, leading the P-polarized component L _P of them in the direction of the condenser lens 532, the condenser lens S-polarized component L _S 535 Lead in the direction of

Condenser lens 532 condenses the P-polarized component _{L P} incident thereon, leads to integrating sphere 533. Further, the condenser lens 535 collects the S-polarized component L _S incident thereon and guides it to the integrating sphere 536. By providing these condensing lenses 532 and 535, even when some variation occurs in the position and direction of the optical path, the influence of the variation is minimized, and the P-polarized component L _P and the S-polarized component L _S. Can be reliably incident on the subsequent optical system.

Photodetectors 534 and 537 are arranged in the detector openings of the integrating spheres 533 and 536, respectively. The light incident on the integrating sphere is detected by the photodetectors 534 and 537 regardless of the direction of the incident light. Led to the face. These integrating spheres 533 and 536, the influence of the optical path change between the P-polarized component L _P and S-polarized component L _S after being branched by the polarizing beam splitter 531 is minimized.

The photodetectors 534 and 537 include, for example, a photoelectric conversion element such as a photodiode (PD). The photodetector 534 generates and outputs an electrical signal (detection signal) indicating the intensity of the P-polarized light component L _P. The photodetector 537 generates and outputs an electrical signal (detection signal) indicating the intensity of the S-polarized component L _S.

These light sources 510, the prisms 121 and 122, wafer 100, and, the light receiving unit 530, for the same reason as that described in the first embodiment, the light _{L I} emitted from the light source unit 510 is incident on the wafer 100 In this case, the positional and angular relationships are adjusted so that the incident angle is preferably about 35 ° to 85 °, and more preferably about 60 ° to 75 °.

The signal processing unit 150 controls each unit of the wafer temperature measuring apparatus and calculates the wafer temperature. When the signal processing unit 150 controls the drive circuits 511 and 514 of the light source unit 510 to alternately operate in a time division manner, a detection signal indicating the intensity of the P-polarized component of the ultraviolet light is received from one photodetector 534. D _UVP and detection signal D _VSP representing the intensity of the P-polarized component of visible light are alternately output. The other photodetector 537 alternately outputs a detection signal D _UVS representing the intensity of the S-polarized component of the ultraviolet light and a detection signal D _VSS representing the intensity of the S-polarized component of the visible light. The signal processing unit 150 calculates the temperature of the wafer 100 based on the detection signals D _UVP , D _UVS , D _VSP , and D _VSS acquired as described above.

The temperature T of the wafer 100 includes four detection signals D _UVP , D _UVS , D _VSP , and a function f (D _UVP , D _UVS , D _VSP , D _VSS ) having D _VSS as variables and parameters calibrated in advance. Is calculated using The function f and the parameter are detected from the temperature measurement apparatus shown in FIG. 12, for example, by detecting the detection light and the reference light while measuring the temperature of the test wafer by the contact method, and measuring the actual temperature value and the detection signals D _UVP , D _{UVS, D VSP,} and _is determined by performing a calculation (for example, regression analysis, etc.) by using the _{D VSS.}

Specifically, for example, the following calculation method is given.
First, by using the following equations (1) and (2), the relative value R _UV between the intensity of the P-polarized component and the intensity of the S-polarized component of the ultraviolet light in the reflected light from the wafer 100 and visible A relative value R _VS between the intensity of the P-polarized light component and the intensity of the S-polarized light component is obtained.
R _UV = (a ₁ D _UVP ² + a ₂ D _UVP + a ₃ ) / (a ₄ D _UVS ^P 2 + a ₅ D _UVS + a ₆ ) (1)
R _VS = (b ₁ D _VSP ² + b ₂ D _VSP + b ₃ ) / (b ₄ D _VSS ^P 2 + b ₅ D _VSP + b ₆ ) (2)
In the expressions (1) and (2), a _{1 to} a ₆ and b _{1 to} b ₆ are parameters calibrated in advance.

Next, by using the relative value R _VS obtained by the equation (2), the correction parameters x _{1 to} x ₃ are calculated by the following equations (3) to (5).
x ₁ = c ₁ R _VS ² + c ₂ R _VS + c ₃ (3)
x ₂ = d ₁ R _VS ² + d ₂ R _VS + d ₃ (4)
^{_{x 3 = e 1 R VS 2}} + e 2 R VS + e 3 ... (5)
In the equations (3) to (5), c _{1 to} c ₃ , d _{1 to} d ₃ , and e _{1 to} e ₃ are parameters calibrated in advance.

Further, the temperature T is calculated by the following equation (6) using the R _UV obtained by the equation (1) and the correction parameters x _{1 to} x ₃ .
T = x ₁ R _UV ² + x ₂ R _UV + x ₃ (6)

Here, the relative value R _UV represented by the equation (1) is sensitive to the temperature change of the wafer and is also affected by the surface state of the wafer (the thickness of the oxide film). It is a function of the wafer temperature and the surface condition because it expresses the relationship with the S-polarized component of the ultraviolet light that is affected by the wafer temperature condition but is not affected by the wafer surface condition. On the other hand, the relative value R _VS represented by the equation (2) is not significantly affected by the temperature change of the wafer, but is the difference between the P-polarized component and the S-polarized component of visible light that is affected by the surface state of the wafer. Since the relationship is expressed, it can be said that it is almost a function of the surface state of the wafer. Therefore, by using the correction values x _{1 to} x ₃ obtained based on the relative value R _UV and the relative value R _VS , the influence of the oxide film or the like formed on the wafer surface is removed, and the correct parameter The wafer temperature can be calculated.

In the present embodiment, the relative values R _UV and R _VS of the P-polarized component and the S-polarized component in the reflected light L _UV and L _VS from the wafer 100 are calculated based on the equations (1) and (2). The relative value may be a simple ratio between the P-polarized component and the S-polarized component, or may be calculated based on a function other than a quadratic function as shown in the equations (1) and (2).

Further, the relative value can also be used as the reference value and the correction value without being limited to the combination described in the present embodiment. That is, the S-polarized component serving as the reference value (relative value denominator) is not necessarily the same as the wavelength of the P-polarized component. Specifically, the same S polarization component may be used as a reference value between two relative values (for example, D _UVP / D _VSS and D _VSP / D _VSS , or D _UVP / D _UVS and D _VSP / D _UVS ) The P-polarized component and the S-polarized component may be used between two relative values (D _UVP / D _VSS and D _VSP / D _UVS ). This is because the components other than the P-polarized component of ultraviolet light are not significantly affected by the temperature change of the wafer, and can be said to represent the change in the surface state of the wafer exclusively.

In the present embodiment, the temperature T is calculated as a function f (R _UV ) of the relative value R _UV by separately obtaining a correction parameter. However, the temperature T is a function f ′ (R R) of the relative values R _UV and R _{VS. UV} , R _VS ), and further, the detection signals D _UVP , D _UVS , D _VSP , and D _VSS function f ″ (D _UVP , D _UVS , D _VSP , D _VSS ) You may calculate based on.

  Further, the equation for obtaining the function of temperature T and the correction parameter is not necessarily the quadratic function shown in equations (3) to (6), and a linear function or another multidimensional function is used. May be. Depending on the size of the wavelengths of ultraviolet light and visible light irradiated on the wafer 100 and the combination of wavelengths, there may be a complicated function. Strictly speaking, the S-polarized light component and the P-polarized light component contained in the reflected light from the wafer affect the temperature and the state of the interface between the wafer and the oxide film in addition to the thickness of the oxide film. Therefore, when the intensity of the S-polarized light component is calibrated based on the actually measured value, it is considered that the function becomes a more complicated function. However, since such an influence is very small compared to the temperature dependence of the P-polarized component of ultraviolet light, there is no problem even if the method described in this embodiment is used practically.

  In the above description, the case where the temperature of the wafer 100 obtained based on the P-polarized component of the ultraviolet light is corrected according to the surface state of the wafer 100 (such as adhesion of an oxide film) has been described. However, when there is no need to perform a new correction, for example, when there is no change in the thickness of the oxide film, only the drive circuit 511 may be operated under the control of the signal processing unit 150. Further, correction may be performed as necessary by operating the drive circuit 514 at a predetermined timing or cycle.

  Next, a wafer temperature measuring apparatus according to the sixth embodiment of the present invention will be described. FIG. 13 is a schematic diagram showing the configuration of the wafer temperature measuring apparatus according to the present embodiment. In this embodiment, the measurement accuracy is further improved by irradiating the wafer 100 with three types of light including ultraviolet light.

  As shown in FIG. 13, the wafer temperature measurement apparatus according to the present embodiment includes a light source unit 610, prisms 121 and 122, a light receiving unit 530, a signal amplifier 140, and a signal processing unit 150. The configurations and operations of the prisms 121 and 122, the light receiving unit 530, the signal amplifier 140, and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

  The light source unit 610 includes driving circuits (DR) 611, 616, and 620, light source devices (LS) 612, 617, and 621, collimating lenses 613, 618, and 622, polarizing elements 614, 619, 623, wavelength combining elements 615 and 624, and an optical chopper 625.

  The drive circuits 611, 616, and 620 control the operations of the light source devices 612, 617, and 621, respectively. The operations of the drive circuits 611, 616, and 620 are controlled by the signal processing unit 150 so as to sequentially operate in time division.

The light source device 612 generates, for example, ultraviolet light L _UV having a wavelength near 365 nm. The light source device 617 generates visible light L _V1 having a first wavelength. Further, the light source device 621 generates visible light _LV2 having a second wavelength different from the first wavelength. In the present embodiment, light-emitting diodes that generate non-polarized light are used as the light source devices 612, 617, and 621.

  As the light source devices 612, 617, and 621, a device that emits pre-polarized light, such as a laser diode (LD), may be used. In that case, polarizing elements 614, 619 in the subsequent stages are used. And 623 can be omitted. In that case, as described later, it is necessary to adjust the arrangement of the light source devices so that the light emitted from the light source devices is incident on the subsequent wavelength combining element in an appropriate polarization state.

The collimating lenses 613, 618, and 622 form parallel beams by transmitting the light emitted from the light source devices 612, 617, and 621, respectively.
The polarizing elements 614, 619, and 623 are linearly polarized by transmitting a parallel beam incident through the collimating lens.

The wavelength synthesizing element (dichroic mirror) 615 reflects the ultraviolet light L _UV incident through the polarizing element 614 to guide it in the direction of the light chopper 625 and transmit other light. The polarization direction of the polarization element 614 is adjusted so that either the P-polarization component or the S-polarization component of the light linearly polarized by the polarization element 614 enters the wavelength synthesis element 615. Yes. The reason for this is that an environmental change such as temperature occurs in the dichroic mirror, so that the polarization state (ratio between the P-polarized component and the S-polarized component) of the light reflected or transmitted by the dichroic mirror is affected. This is because the polarization state does not change when only one of the components is incident.

The wavelength synthesizing element 624 guides the visible light L _V1 in the direction of the optical chopper 625 and transmits the other wavelength components, that is, the visible light L _V2 in the direction of the optical chopper 625. In contrast to the wavelength synthesizing element 624, the polarizing elements 619 and 623 are configured so that either the P-polarized component or the S-polarized component in the linearly polarized light is used in order to prevent a change in the polarization state in the wavelength synthesizing element 624. The polarization direction is adjusted so as to be incident.

  Further, in the same manner as described in the fifth embodiment, the wavelength combining elements 615 and 624 preferably have a ratio of the P-polarized component and the S-polarized component in the light incident on the wafer 100 via the prism 121. It arrange | positions so that it may become about 3 to 1.

The optical chopper 625 controls the timing at which light is emitted from the light source unit 610 by chopping the ultraviolet light L _{UV and the} visible light L _V1 and L _V2 guided by the wavelength synthesis elements 615 and 624 at a predetermined timing or frequency. To do. The optical chopper 625 outputs an on / off signal used for causing the signal amplifier 140 to perform a lock-in operation.

In the present embodiment, the light source unit 610 is provided with three light sources that sequentially operate in a time-sharing manner. Therefore, from the photodetector 534 of the light receiving unit, the detection signal D _UVP indicating the intensity of the P-polarized component of the ultraviolet light L _UV reflected by the wafer 100 and the intensity of the P-polarized component of the first visible light L _V1 are obtained. The detection signal P _V1P representing the detection signal D _V2P representing the intensity of the P-polarized component of the second visible light L _V2 is sequentially output. Further, from the photodetector 537, a detection signal D _UVS representing the intensity of the S-polarized component of the ultraviolet light L _UV reflected by the wafer 100 and a detection signal representing the intensity of the S-polarized component of the first visible light L _V1. P _V1S and a detection signal D _V2S representing the intensity of the S-polarized component of the second visible light L _V2 are sequentially output. The signal processing unit 150 calculates the temperature of the wafer 100 based on these six types of detection signals.

Specifically, for example, the following calculation method is given.
First, as described in the fifth embodiment of the present invention, the relative value of the P-polarized component and the S-polarized component in the reflected light L _UV , L _V1 , L _V2 from the wafer 100 according to the equation (1) and the like. R _UV , R _V1 , and R _V2 are obtained. The relative value may be a simple ratio D _UVP / D _UVS , D _V1P / D _V1S , D _V2P / D _V2S of the detection signal, or a ratio of a predetermined function as in the fifth embodiment. There may be.

Next, by using the equations (3) to (5), correction parameters x _{1 to} x ₃ based on the relative value R _V1 and correction parameters y _{1 to} y ₃ based on the relative value R _V2 are calculated. To do. Furthermore, based on the following equation, average values z _{1 to} z ₃ of the correction parameters are obtained.
z ₁ = (x ₁ + y ₁ ) / 2
z ₂ = (x ₂ + y ₂ ) / 2
z ₃ = (x ₃ + y ₃ ) / 2
Using these averaged correction parameters z _{1 to} z ₃ , the temperature T of the wafer 100 is calculated by the following equation (7).
T = z ₁ R _UV ² + z ₂ R _UV + z ₃ (7)

  As described above, in the sixth embodiment of the present invention, more accurate correction can be performed in the temperature measurement of the wafer 100 by increasing the detection signals used for correction. Further, by further providing a light source system that generates visible light in the light source unit 610 illustrated in FIG. 13, the accuracy of correction can be further increased.

Also in the present embodiment, as in the fifth embodiment, the combination of the P-polarized component and the S-polarized component when obtaining the relative value _{RUV and the} like is not limited to the same wavelength. That is, the relative value of the ultraviolet light with respect to the P-polarized light component is used as a variable of the function for obtaining the temperature T (formula (7)), and other relative values may be used for calculating the correction parameter. Various functions other than the quadratic function can be used as the formula for calculating the function of the temperature T and the correction parameter. Further, by using the relative values R _UV , R _V1 , and R _V2 and the detection signals D _UVP , D _UVS , D _V1P , D _V1S , D _V2P , and D _V2S as variables, the temperature T can be directly set. A calculated function may be used.

  Next, a wafer temperature measuring apparatus according to the seventh embodiment of the present invention will be described. FIG. 14 is a schematic diagram showing the configuration of the wafer temperature measuring apparatus according to the present embodiment. In the present embodiment, the temperature is measured based on the reflected light from the wafer 100 using a single light source, and a mechanism for adjusting the optical axes of incident light and reflected light on the wafer 100 is provided. Yes.

  As shown in FIG. 14, the wafer temperature measuring apparatus according to this embodiment includes a light source unit 710, a wafer support 721, position adjustment mechanisms 722 to 724, a light receiving unit 730, a signal amplifier 140, and a signal processing unit. 150 and a position detection unit 760. The configurations and operations of the signal amplifier 140 and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

The light source unit 710 includes a drive circuit (DR) 711, a light source device (LS) 712, and a collimator lens 713.
The drive circuit 711 controls the operation of the light source device 712. The light source device 712 includes, for example, a low-pressure or high-pressure mercury lamp or a mercury xenon lamp, and emits light including a wavelength component in the ultraviolet region and a wavelength component in the visible region.
The collimating lens 713 forms a parallel beam by transmitting the light emitted from the light source device 712.

  The wafer support 721 is, for example, a heater with an electrostatic chuck, and fixes the wafer 100 and keeps it at a predetermined temperature. The wafer support base 721 is formed with an optical path 70 for allowing the light emitted from the light source unit 710 to enter the wafer 100 and guiding the reflected light from the wafer 100 to the light receiving unit 730.

  The position adjustment mechanism includes support members 722 to 724. The support member 722 couples the light source unit 710 and the light receiving unit 730, and the support members 723 and 724 couple the support member 722 and the wafer support base 721. These support members 722 to 724 are desirably formed of a material having a low coefficient of thermal expansion, such as Invar, synthetic quartz, Zerodur (registered trademark), quartz glass, and low expansion polycrystalline glass. Thereby, it is possible to suppress the change in the optical path due to the change in the relative positional relationship of the light source unit 710 and the like due to the influence of heat.

  Position adjusting portions 722a, 722b, 723a, and 724a are provided at the coupling portions of the support members 722 to 724. The position adjustment units 722a, 722b, 723a, and 724a are mechanically adjusted based on the detection result of the position detection unit 760 described later, thereby making the relative relationship between the light source unit 710, the light receiving unit 730, and the wafer support base 721. The position is adjusted.

The light receiving unit 730 includes a wavelength separation filter group 731, polarizing prisms 732 and 733, a plurality of diffusion plates 734, a plurality of lenses 735, and photodetectors 736 to 739.
The wavelength separation filter group 731 includes three wavelength separation filters 71 to 73 having the same characteristics. Each of the wavelength separation filters 71 to 73 transmits the wavelength component λ _UV , totally reflects the wavelength component λ _1, and functions as a half mirror for the wavelength component λ ₂ . In the wavelength separation filter group 731, the wavelength component λ _UV included in the reflected light from the wafer 100 passes through the wavelength separation filters 71 and 73 and is guided in the direction of the polarization prism 732. Further, the wavelength component λ ₁ is guided from the wavelength separation filters 71 and 72 to the direction of the polarizing prism 733. Furthermore, the wavelength component λ ₃ is guided in the direction of the position detection unit 760 by being transmitted through the wavelength separation filter 71 and reflected from the wavelength separation filter 73.

  Here, in general, since the wavelength separation filter has polarization dependency, the polarization state (the ratio between the P-polarized component and the S-polarized component) is simply reflected or transmitted in the light after reflection or transmission. ) Will change. Therefore, in the present embodiment, the wavelength separation filter 71 and the wavelength separation filter 72 are disposed so as to make an angle of 90 ° with the optical axis as a rotation axis, and the wavelength separation filter 71 and the wavelength separation filter 73 are disposed on the optical axis. By arranging them so as to be 90 ° with respect to each other as a rotation axis, a change in polarization state is prevented based on the following principle.

With respect to P-polarized light and S-polarized light reflected by the wafer 100, if the reflectance of the P-polarized component in the wavelength separation filter 71 is R _P and the reflectance of the S-polarized component is R _S , the light is rotated by 90 °. in the wavelength separation filter 72 which is arranged, P 'reflectivity _{R S} of and the S-polarized component' reflectance _{R P} polarized light component, _{R P} '= _{R S,} and, _{R S'} becomes = _{R P} .

Also, assuming that the intensity of the P-polarized component of the light incident on the wavelength separation filter 71 is I _P and the intensity of the S-polarized component is I _S , the intensity of these polarized components after being reflected by the wavelength separation filter 71 is I It changes to _P × R _P (P polarization component) and I _S × R _S (S polarization component). When such light is further reflected by the wavelength separation filter 72, the intensity of each polarization component in the reflected light changes as follows.
P polarization component: I _P × R _P × R _P '= I _P × R _P × R _S
S-polarized light _{component: I S × R S × R} S '= I S × R S × R P
Eventually, the ratio of the P-polarized component and the S-polarized component does not change before entering the wavelength separation filter 71 and after being reflected by the wavelength separation filter 72.

Further, assuming that the transmittance of the P-polarized component of the wavelength separation filter 71 is T _P and the transmittance of the S-polarized component is T _S , the P-polarized component in the wavelength separation filter 73 arranged to be rotated by 90 ° with respect to it. The transmittance T _P ′ and the transmittance T _S ′ of the S-polarized component are T _P ′ = T _S and T _S ′ = T _P. Accordingly, the intensity of the light transmitted through the wavelength separation filters 71 and 73 changes as follows.
P-polarized light _{component: I P × T P × T} P '= I P × T P × T S
S-polarized light _{component: I S × T S × T} S '= I S × T S × T P
Eventually, the ratio of the P-polarized component and the S-polarized component does not change before entering the wavelength separation filter 71 and after passing through the wavelength separation filter 73.
Furthermore, since the wavelength separation filters 71 to 73 are brought close to each other and thermally placed in the same environment, their polarization dependency can be made uniform, so that the change in the polarization state can be effectively suppressed.

The polarization prism 732 separates the ultraviolet light (wavelength component λ _UV ) separated by the wavelength separation filter group 731 according to the polarization direction, guides the P polarization component λ _UVP toward the photodetector 736, and generates the S polarization component λ. _{The UVS} is guided in the direction of the photodetector 737. The polarizing prism 733 separates the visible light (wavelength component λ ₁ ) separated by the wavelength separation filter group 731 according to the polarization direction, guides the P-polarized component λ _1P toward the photodetector 738, and generates S-polarized light. The component λ _1S is guided in the direction of the photodetector 739.

  The diffusion plate 734 is, for example, ground glass or a fly-eye lens. The diffusion plate 734 and the lens 735 arranged at the subsequent stage are provided in order to make the intensity on the light irradiation surface uniform. Thereby, when light enters the photodetectors 736 to 739, an error caused by the optical axis fluctuation is minimized. When the distance between the diffuser plate 734 and the photodetectors 736 to 739 is long, the same effect can be obtained even if the lens 735 is omitted.

The photodetectors 736 to 739 are a detection signal representing the P-polarized component λ _UVP of the ultraviolet light, a detection signal representing the S-polarized component λ _UVS of the ultraviolet light, a detection signal representing the P-polarized component λ _1P of the visible light, and visible A detection signal representing the S polarization component λ _1S of the light is output. These detection signals are input to the signal processing unit 150 through the amplifier 140 and used to calculate the temperature of the wafer 100. The method for calculating the wafer temperature is the same as that described in the fifth embodiment.

  These photodetectors 736 to 739 are arranged so that the optical path lengths from the wavelength separation filter 71 are the same. As a result, even when fluctuations occur in the optical axis of the light incident on the light receiving unit 730, the influence is equal between the photodetectors 736 to 739, so that the light is output from the photodetectors 736 to 739, respectively. The generation of errors can be suppressed by canceling the influence of fluctuations in the detection signal.

The position detection unit 760 includes a condenser lens 761 and a position detection element (PSD) 762. The condenser lens 761 condenses the light (wavelength component λ ₂ ) transmitted through the wavelength separation filter 71 of the light receiving unit 730 and reflected by the wavelength selection filter 72 and guides it to the position detection element 762. The position detection element 762 detects the position of the received light, generates a detection signal, and outputs the detection signal to the signal processing unit 150. The signal processing unit 150 detects a positional shift or an angular shift of light irradiated on the wafer 100 based on the detection signal, and performs alignment by operating the position adjusting units 722a, 722b, 723a, and 724a.
Note that the position detection unit 760 may be detachably attached to the light receiving unit 730 and may be attached and used only when performing alignment.

  As described above, in the present embodiment, alignment is performed using a part of the light reflected by the wafer 100 to irradiate light at an appropriate incident angle at an appropriate position of the wafer 100. become able to. In the fifth and sixth embodiments of the present invention, an optical system that branches a part of the received light is added to the light receiving unit, and a position detection unit as in the present embodiment is provided to perform alignment. May be performed.

Next, a wafer temperature measuring apparatus according to the eighth embodiment of the present invention will be described. FIG. 15 is a schematic diagram showing a configuration of the wafer temperature measuring apparatus according to the present embodiment. The present embodiment is characterized in that a plurality of types of detection signals are acquired in a time division manner using a single photodetector.
As shown in FIG. 15, the wafer temperature measuring apparatus according to the present embodiment includes a light source unit 810, prisms 121 and 122, a light receiving unit 830, a signal amplifier 140, and a signal processing unit 150. The configurations and operations of the prisms 121 and 122, the signal amplifier 140, and the signal processing unit 150 are the same as those in the wafer temperature measuring apparatus shown in FIG.

The light source unit 810 includes drive circuits (DR) 811 and 814, light source devices (LS) 812 and 815, collimating lenses 813 and 816, and a polarizing prism 817.
The drive circuits 811 and 814 control operations of the light source devices 812 and 815, respectively. The operations of the drive circuits 811 and 814 are controlled by the signal processing unit 150 so as to operate alternately in a time division manner.

The light source device 812 is, for example, a laser diode (LD) that generates ultraviolet light L _UV having a wavelength of around 365 nm, and is arranged such that light emitted from the light source device 812 enters the polarizing prism 817 in a P-polarized state. .
Light source device 815, e.g., a laser diode having a wavelength for generating a visible light L _VS is near 650 nm, light emitted therefrom is arranged to be incident on the polarizing prism 817 in the state of S-polarized light.
The collimating lenses 813 and 816 form parallel beams by transmitting light emitted from the light source devices 812 and 815, respectively.

The polarizing prism 817 reflects or transmits incident light according to the polarization direction. In the present embodiment, the one that reflects the P-polarized component and transmits the S-polarized component is used. Thereby, the ultraviolet light L _UV emitted from the light source device 812 is reflected by the polarizing prism 817 and guided in the direction of the prism 121, and the visible light L _VS emitted from the light source device 815 passes through the polarizing prism 817 and passes through the prism 121. Led in the direction of. Further, when the polarization state of the light incident on the polarizing prism 817 is set to only the P-polarized component or only the S-polarized component, even when an environmental change such as temperature occurs in the polarizing prism 817, the light is reflected by the polarizing prism 817. Alternatively, it is possible to prevent a change in the polarization state (the ratio between the P-polarized component and the S-polarized component) of the transmitted light.

The polarizing prism 817 is arranged so that the ratio of the P-polarized component and the S-polarized component with respect to the wafer 100 in the light incident on the wafer 100 via the prism 121 is about 1: 1.
The polarizing prism has durability against environmental changes and has excellent long-term stability as compared to a wavelength selective filter formed of a multilayer film. Further, a Wollaston prism may be used instead of the optical prism 817.

The light receiving unit 830 includes an optical modulator 831, a polarizing element 832, a diffusion plate 833, a lens 834, and a photodetector (PD) 835.
The optical modulator 831 is formed by, for example, a Pockels cell, and changes the polarization state of light transmitted therethrough according to the supplied electric signal. Here, the Pockels cell is an optical element using an EO effect (electro optic effect) in which the refractive index and anisotropy of the crystal change when an electric field is applied to the crystal. By controlling the electric field applied to the Pockels cell, the polarization plane of the light passing through it can be rotated by a desired angle (eg, 90 °). The operation of the optical modulator 831 is controlled by the signal processing unit 150.
Alternatively, the optical modulator 831 may be configured by a drive mechanism that mechanically rotates an element such as a wave plate using the optical axis as a rotation axis.

The polarization element 832 transmits a predetermined polarization component (P-polarization component in the present embodiment) included in the light transmitted through the light modulator 831.
The diffusing plate 833 is, for example, a ground glass or a fly-eye lens, and is provided with the lens 834 disposed in the subsequent stage in order to make the intensity on the light irradiation surface uniform.

In this wafer temperature measuring apparatus, by alternately operating the drive circuits 811 and 814 of the light source unit 810, ultraviolet light and visible light emitted from the light source unit 810 and reflected by the wafer 100 are alternately received by the light receiving unit 830. Received light.
Here, when the light modulator 831 is in an inactive state, the reflected light (light L _R ) from the wafer 100 passes through the light modulator 831 as it is without changing the polarization direction. Thus, P-polarized light component contained in the light L _R is transmitted through the polarizing element 832. On the other hand, when the optical modulator 831 is activated, the polarization direction of the light _LR is rotated by 90 ° by the optical modulator 831. Thus, P-polarized light component after polarization direction is rotated (i.e., S-polarized light component contained in the light L _R) is transmitted through the polarizing element 832. Thus, by switching the active state of the optical modulator 831, and the P-polarized light component contained in the light L _R and the S-polarized component through the diffusion plate 833 and lens 834, alternately detected by the light detector 835 Is done.

Therefore, the operation timing of the driving circuit 811 and 814, by synchronizing the activation timing of the light modulator 831, a detection signal indicative of P-polarized component of the ultraviolet light L _UV, the S-polarized component of the ultraviolet light L _UV a detection signal indicative of a, a detection signal representing the P-polarized light component of the visible light L _VS, and a detection signal indicative of the S-polarized light component of the visible light L _VS, through a signal amplifier 140, are sequentially input to the signal processing unit 150 . The signal processing unit 150 calculates the temperature of the wafer 100 based on these detection signals. The method for calculating the wafer temperature is the same as that described in the fifth embodiment.

Thus, according to the present embodiment, four types of detection signals can be acquired by one photodetector, so that the number of devices can be reduced and the apparatus can be downsized. Moreover, since the loss of light is reduced, the temperature can be measured efficiently. In addition, since the optical path from the reflection by the wafer 100 to the detection by the photodetector 835 is the same for all light components, errors caused by fluctuations in the optical path and non-uniform sensitivity in the photodetector. Can be kept to a minimum.
In this embodiment as well, alignment may be performed by using a part of the light reflected by the wafer 100 as in the seventh embodiment of the present invention.

  When measuring the wafer temperature using the wafer temperature measuring apparatus according to the embodiment of the present invention described above, the calibrated parameters required in the mathematical formula used to calculate the temperature are not obtained in advance. must not. It is desirable to correct these parameters in response to changes in the characteristics of the optical element. Therefore, a method for calibrating or correcting parameters will be described below.

  16A and 16B are diagrams for explaining a parameter calibration method in the wafer temperature measuring apparatus according to the embodiment of the present invention. FIG. 16A is a partial cross-sectional view of the front of the apparatus, and FIG. 16B is a plan view. . When the parameters are calibrated and corrected in the temperature measuring apparatus, first, a calibration test piece 563 such as a wafer having a plurality of film thicknesses, to which a temperature sensor 562 such as a resistance temperature detector is attached, is prepared. Is attached to an arm 564 that can be rotated by a rotary motor 565 via an actuator 561 that moves in the vertical direction. The temperature sensor 562 may be attached in the vicinity of the calibration test piece 563.

  Next, the calibration test piece 563 is placed on the wafer support 550, and while observing the temperature sensed by the temperature sensor 562, a time is allowed until the calibration test piece 563 reaches a thermal equilibrium state. When it is confirmed that the calibration test piece 563 has reached the thermal equilibrium state, the light source unit 510, 610, 710, or 810 emits light to the calibration test piece 563, and the light receiving units 530, 730, or 830 are irradiated. The temperature is measured based on the output signal of the included photodetector.

  Further, while changing the temperature of the calibration test piece 563 by adjusting the temperature, the temperature is measured based on the output signal of the photodetector in the same manner as described above. Thereby, a plurality of types of measurement data based on the output signals of the photodetectors at a plurality of film thicknesses and a plurality of temperatures can be obtained. By using a method such as the least square method based on the plurality of types of measurement data obtained in this way, it is possible to calibrate parameters necessary for the mathematical formula used to calculate the temperature.

  In addition, the ratio of the P-polarized component and the S-polarized component in ultraviolet light and visible light is the variation of the optical axis and the characteristics of the optical element, the temperature characteristics and characteristics of the photodetector, the temperature dependence of the electric circuit, etc. Therefore, if the first determined parameter is used, an error occurs in the temperature measurement value. Therefore, it is desirable to correct the parameters by periodically repeating the calibration method or a part thereof. For example, the parameter may be corrected by measuring the temperature of the calibration test piece 563 having one type of film thickness based on the output signal of the photodetector.

  Furthermore, in the fifth, sixth, and eighth embodiments, an optical element that detects reflected light between ultraviolet light and visible light or infrared light in the light receiving unit 530 or 830, a photodetector, Since the electric circuit is the same, if the output of the photodetector by visible light or infrared light is measured on a wafer having the same film thickness as the calibration test piece 563 used for calibrating the parameters, the temperature Even if the temperature sensing using the sensor 562 is omitted, the parameter can be corrected.

  Next, another parameter calibration method in the wafer temperature measuring apparatus according to the fifth to eighth embodiments of the present invention will be described. Measurement to first calibrate parameters of a wafer coated with a stable material whose reflectivity does not vary greatly with temperature (eg, gold or silver), or a wafer made of such a stable material Measure simultaneously when performing. Thereafter, by periodically measuring the wafer, it is possible to know a change in characteristics from the time of parameter calibration, so that the parameter can be corrected.

  As described above, when a stable material with little change due to temperature is used, the ratio of the P-polarized component and the S-polarized component in ultraviolet light and visible light does not change much depending on the temperature, which is necessary in the previous calibration method. This eliminates the need for the measured temperature value and shortens the work time.

  When such calibration or correction is performed, a calibration test piece may be mixed in a wafer processed in the semiconductor manufacturing process, and measurement may be performed periodically. Alternatively, a calibration test piece may be prepared separately from the wafer to be processed, and the measurement may be performed by periodically setting the calibration test piece in the apparatus instead of the processed wafer. Furthermore, a mechanism for setting the calibration test piece on the wafer support may be provided in advance in the apparatus. In that case, the wafer to be processed and the test specimen for calibration do not necessarily have the same dimensions.

  As described above, according to the fifth to eighth embodiments of the present invention, the reflection intensity of the P-polarized component of ultraviolet light having a very large dependence on temperature and the other components having a small dependence on temperature. Since the temperature of the temperature measurement target is calculated based on the ratio of the reflection intensity of the ultraviolet light (ie, the S-polarized component of ultraviolet light, the P-polarized component and the S-polarized component of visible light), the oxidation formed on the surface of the temperature measurement target The influence of the film or the like can be canceled. Therefore, accurate temperature measurement with reduced errors can be performed for each type of wafer, regardless of the surface state of the wafer that is the temperature measurement target, that is, the thickness and physical properties of the oxide film.

  Next, a wafer temperature measuring apparatus according to the ninth embodiment of the present invention will be described. The wafer temperature measuring apparatus according to the present embodiment can accurately and accurately adjust the wafer temperature in situ even in a low-temperature process regardless of the surface state of the temperature measurement target (for example, when an oxide film is formed). It is for measuring.

  Here, as described above, the inventors of the present application formed reflections on the surface of the object to be measured (wafer), reflection on the surface of the oxide film, and between the oxide film surface and the silicon surface. Since multiple reflection occurs, it was confirmed that the detected reflection intensity greatly fluctuated due to light interference. For this reason, the absolute value of the temperature may be unclear.

  FIG. 17 is a table showing the reflectance of the P-polarized component and the S-polarized component with respect to the silicon oxide film, and is obtained by simulation with the refractive index of the silicon oxide film being n = 1.46 and the wavelength of incident light being 365 nm. It is a thing. FIG. 18 is a graph showing the incident angle dependence of the reflectance of the P-polarized component and the S-polarized component with respect to the silicon oxide film, and is created based on FIG.

  In general, when light is incident on a boundary surface between two media having different refractive indexes, an electric vector is included in an incident surface (a surface including a normal surface of a reflecting surface and a traveling direction of light) (that is, a surface). There is an incident angle such that the reflectance of the (P-polarized component) becomes zero. Such an angle is called a Brewster angle (Brewster's angle). 17 and 18, in the silicon oxide film having a refractive index of n = 1.46, it can be seen that the Brewster angle is around 55 ° where the reflectance of the P-polarized component is extremely low. Further, within a predetermined range including the Brewster angle (for example, a range of less than Δ25 ° including the Brewster angle is 40 ° <θ <65 °, and desirably a range of about Δ15 ° including the Brewster angle is 45. (° ≦ θ ≦ 60 °), the reflectance of the P-polarized component is considerably lower than the other ranges.

  Therefore, in order to accurately calculate the temperature of the measurement object, the inventors of the present application use a P-polarized component of ultraviolet light that is sensitive to a temperature change of the measurement object, with an incident angle in the vicinity of the Brewster angle (predetermined including the Brewster angle). We examined to irradiate the measurement target so that This is because the reflection intensity from only the measurement target can be detected by suppressing reflection between the surface of the oxide film and between the measurement target and the oxide film.

  FIG. 19 is a schematic diagram showing a configuration of a wafer temperature measuring apparatus according to the ninth embodiment of the present invention. As shown in FIG. 19, the wafer temperature measuring apparatus according to the present embodiment includes a first optical system including a light source unit 910 and a light receiving unit 920, a second optical system including a light source unit 930 and a light receiving unit 950, A signal amplifier (AMP) 140 and a signal processing unit 150 are included. The device configurations of the signal amplifier 140 and the signal processing unit 150 are the same as those in the wafer temperature measuring device shown in FIG.

  In the first optical system, the light emitted from the light source unit 910 is applied to the wafer 100 so that the incident angle is larger than the Brewster angle (desirably, the incident angle is larger than about 60 ° and not larger than about 85 °). The positions and angles of the light source unit 910, the wafer 100, and the light receiving unit 920 are adjusted so that the incident light and the reflected light are received by the light receiving unit 920. On the other hand, in the second optical system, the light emitted from the light source unit 930 is incident on the wafer 100 so that the incident angle is in the vicinity of the Brewster angle (for example, about 45 ° or more and about 60 ° or less), and the reflection thereof. The positions and angles of the light source unit 930, the wafer 100, and the light receiving unit 950 are adjusted so that the light is received by the light receiving unit 950.

  In the present embodiment, the reason for providing these optical systems is as follows. As described above, in order to remove the influence of the oxide film formed on the surface of the wafer 100, the P-polarized component needs to be incident on the wafer 100 so as to be close to the Brewster angle. Two optical systems are provided. However, as the incident angle becomes smaller, the difference in reflectance between the P-polarized component and the S-polarized component becomes smaller, so that a very high measurement accuracy cannot be obtained in the second optical system. Therefore, in the present embodiment, a first optical system that irradiates the wafer 100 with an incident angle larger than the Brewster angle is further provided, and a precise change in the wafer temperature measured by the first optical system, The temperature of the wafer 100 is accurately obtained from the absolute value of the temperature measured by the optical system.

  As for the upper limit value of the incident angle in the first optical system, if the incident angle is too large, the expected width of the wafer 100 exceeds the width of the incident light beam, and vignetting (unintended shadows appear). Is provided to avoid it. In the present embodiment, the incident angle in the first optical system is set to a practical range greater than about 60 ° and less than or equal to about 85 °, and preferably greater than about 60 ° and less than or equal to about 75 °.

  The light source unit 910 includes a drive circuit (DR) 911, a light source device (LS) 912, and a collimator lens 913. The drive circuit 911 controls the operation of the light source device 912. The light source device 912 is, for example, a light emitting diode (LED) that generates ultraviolet light having a wavelength near 375 nm. Further, the collimating lens 913 forms a parallel beam by transmitting the ultraviolet light emitted from the light source device 912.

By operating such a light source unit 910, ultraviolet light including a P-polarized component and an S-polarized component irradiates the wafer 100.
As the light source device 912, a light source device that emits linearly polarized light such as a laser diode may be used. In that case, the ratio of the P-polarized component and the S-polarized component in the incident light with respect to the wafer 100 is preferably 3 in order to make the intensity of the P-polarized component and the S-polarized component in the reflected light from the wafer 100 comparable. The position and angle of the light source device are adjusted so as to be about one to one.

The light receiving unit 920 includes a wavelength selection filter 921, a polarization beam splitter 922, integrating spheres 923 and 925, and photodetectors 924 and 926. The wavelength selection filter 921 transmits a predetermined wavelength component, thereby reducing disturbance light from being mixed into the detected light. Further, the polarization beam splitter 922 separates the light incident thereon according to the polarization direction, guides the P-polarized component L _P in the direction toward the photodetector 924, and converts the S-polarized component L _S into the photodetector 926. Lead in the direction of

Photodetectors 924 and 926 are disposed in the detector openings of the integrating spheres 923 and 925, respectively, and the light incident on the integrating sphere is detected by the photodetectors 924 and 926 regardless of the direction of incidence. Led to the face. These integrating spheres 923 and 925, the effects of the optical path change between the P-polarized component L _P and S-polarized component L _S after being branched by the polarizing beam splitter 922 is minimized.

The photodetectors 924 and 926 include photoelectric conversion elements such as photodiodes (PD), for example. Electrical signal generated by the optical detector 924 is outputted as a detection signal R _P representing the intensity of the P-polarized component L _P. The electrical signal generated by the photodetector 926 is output as a detection signal (reference signal) R _S representing the intensity of the S-polarized component L _S.

  The light source unit 930 includes drive circuits (DR) 931 and 936, light source devices (LS) 932 and 937, collimator lenses 933 and 938, beam splitters 934 and 939, photodetectors (PD) 935 and 940, A wavelength synthesis element (wavelength synthesis filter) 941 and a light amount comparison unit (CMP) 942 are included. The drive circuits 931 and 936 control the operations of the light source devices 932 and 937, respectively.

The light source device 932 is, for example, a laser diode (LD) that generates ultraviolet light having a wavelength near 365 nm. Further, the linear collimating lens 933 forms a parallel beam by transmitting the ultraviolet light L _UV emitted from the light source device 932. Further, the beam splitter 934 transmits a part of the incident light and guides it in the direction of the wavelength combining element 941, and reflects the remaining incident light and guides it in the direction of the photodetector 935. The photodetector 935 generates an electrical signal corresponding to the intensity of the incident light.

On the other hand, the light source device 937 is, for example, a laser diode that generates visible light having a wavelength near 650 nm. Further, the collimator lens 938 forms a parallel beam by transmitting the visible light L _VS emitted from the light source device 937. Further, the beam splitter 939 transmits a part of the incident light and guides it in the direction of the wavelength synthesizing element 941, and reflects the remaining incident light and guides it in the direction of the photodetector 940. The photodetector 940 outputs a detection signal corresponding to the intensity of incident light.

The wavelength synthesizing element (for example, dichroic mirror) 941 transmits the ultraviolet light L _UV propagated from the direction of the light source device 932 and reflects the visible light L _VS propagated from the direction of the light source device 937. Thereby, the ultraviolet light L _UV and the visible light L _VS are combined and emitted from the light source unit 930.

The light quantity comparison unit 942 obtains an intensity ratio (light quantity ratio) between the emitted ultraviolet light L _UV and visible light L _VS based on the detection signals output from the photodetectors 935 and 940. Signal representing the light amount ratio obtained by the light amount comparing unit 942 is amplified and output as the correction signal R _R to the signal processing unit 150 to be described later.

  In such a light source unit 930, the position of each optical system is such that the light emitted from the light source devices 932 and 937 enters the wavelength combining element 941 with only the P-polarized component or only the S-polarized component. And the angle is adjusted. The reason is that the polarization state of the light reflected or transmitted by the wavelength synthesizing element 941 (the ratio between the P-polarized component and the S-polarized component) is affected by an environmental change such as temperature in the wavelength synthesizing element 941. This is because the polarization state does not change when only one component of P-polarized light or S-polarized light is incident. Further, the position and angle of the light source unit 930 are adjusted so that light emitted from the light source unit 930 enters the wafer 100 in a P-polarized state.

  The light receiving unit 950 includes a lens 951, apertures (openings) 952 and 953, a wavelength separation element 954, integrating spheres 955 and 957, and photodetectors (PD) 956 and 958. The lens 951 suppresses the spread of reflected light from the wafer 100. The apertures 952 and 953 are provided to remove unnecessary disturbance light.

The wavelength separation element (for example, dichroic mirror) 954 transmits the ultraviolet light L _UVP included in the reflected light from the wafer 100 and guides it in the direction of the photodetector 956 and reflects the visible light L _VSP to detect the light. Guide to 958 direction. The wavelength separation element 954 is a state in which the reflected light from the wafer 100 is only the P-polarized component or only the S-polarized component in order to prevent a change in the polarization state of the light transmitted or reflected by the wavelength separation element 954. The position and the angle are adjusted so as to be incident at.

The photodetector 956 receives light via the integrating sphere 955 and outputs a detection signal R _UVP representing the intensity of the P-polarized component L _UVP of the ultraviolet light. The photodetector 958 receives light via the integrating sphere 957 and outputs a detection signal (reference signal) R _VSP indicating the intensity of the P-polarized component L _VSP of visible light.

Next, a specific example of a method for calculating the wafer temperature in the signal processing unit 150 will be described.
First, the signal processing unit 150 calculates the temperatures _{T 1} based on the detection signal _{R P} and the reference signal _{R S} output from the light receiving unit 920 also detects the signal _{R UVP} and the reference signal output from the light receiving unit 950 calculating the temperature _{T 2} on the basis of the R _VSP.

To determine the temperature _{T 1,} First, the relative value _{R 1} between the reference signal _{R S} and the detection signal _{R P.} Relative value _{R 1} may be a simple ratio _R P / _{R S} of the reference signal _{R S} and the detection signal _{R P,} the ratio of the value after taking the offset _(R P _-α) / _{(R S-} α). Further, the relative value may be obtained by using an appropriate function. For example, R ₁ = (aR _P ² + bR _P + c) / (aR _S ² + bR _S + c) may be used.

Next, the temperature T ₁ is calculated by using a predetermined function f (R ₁ ) having the relative value R ₁ as a variable and a parameter calibrated in advance. This function T ₁ = f (R ₁ ) is a polynomial or a multi-order expression such as f (R ₁ ) = aR + b, f (R ₁ ) = aR _S + b _R + c,. The function f (R ₁ ) and the parameters a, b,... Are detected by detecting the detection light and the reference light while measuring the temperature of the test wafer by the contact method in the temperature measurement apparatus shown in FIG. It can be obtained by performing an operation (for example, regression analysis or the like) using the value, the detection signal _RP, and the reference signal _RS .

Alternatively, instead of using the relative value R ₁ , the temperature T ₁ may be directly calculated using a function f ′ (R _P , R _S ) having the detection signal R _P and the reference signal R _S as variables. The function T ₁ = f ′ (R _P , R _S ) and its parameters are also obtained by using the measured value of the temperature obtained by the contact method, as in the case of the function f (R ₁ ).

On the other hand, the temperature _{T 2,} first, by correcting the detection signal _{R UVP} and the reference signal _{R VSP} based on the correction signal _{R R,} determining the true detection signal _{R UVP} 'and the true reference signal _{R VSP'.} In the light source unit 930 shown in FIG. 19, since two light source devices 932 and 937 are used, such correction is necessary. Therefore, when only one broadband light source device in which the intensity ratio of wavelength components does not change is used, this correction may not be necessary.

Then, a relative value R ₂ between the true detection signal R _UVP ′ and the true reference signal R _VSP ′ is obtained, and the function g (R ₂ ) and the previously calibrated parameters are used in the same manner as the method for calculating the temperature T _1. it allows to calculate the temperature _{T 2.} The function g (R ₂ ) can also be obtained by temperature measurement using a test wafer and calculation (for example, regression analysis). Alternatively, the temperature T ₂ may be calculated using a function g ′ (R _UVP ′, R _VSP ′) using the true detection signal and the reference signal as variables.

Next, a difference ΔT = T ₂ −T ₁ between the temperature T ₂ and the temperature T ₁ is calculated, and the parameter of the function f (R ₁ ) is calibrated based on the difference ΔT. Specifically, the parameter of the function f (R ₁ ) is changed so that the error ΔT approaches 0.
By using the calibrated parameter and function f (R ₁ ) obtained thereby, and the detection signal _RP and the reference signal _RS obtained by the first optical system, an error caused by the surface oxide film is reduced. The reduced temperature of the wafer 100 can be determined.

In the ninth embodiment of the present invention described above, a plurality of detection signals R _UVP and a plurality of detection signals R _UVP obtained by operating the second optical system a plurality of times are used as the temperature T ₂ used when obtaining the error ΔT. The measurement accuracy can be further increased by using the average value of each of the reference signals R _VSP .
Further, the calibration of the parameter of the function f (R ₁ ) using the second optical system may be performed periodically, or may be performed every time the wafer to be measured for temperature is replaced. In the latter case, the operation of the second optical system may be automatically controlled based on a wafer exchange signal supplied from the outside of the wafer temperature measuring apparatus according to the present embodiment.

  Further, in the present embodiment, the S-polarized component of ultraviolet light is used as reference light in the first optical system, but other components can be used as long as the reflection intensity is not dependent on the temperature of the measurement target. It may be used. For example, a P-polarized component or an S-polarized component of visible light can be used.

  As described above, according to the ninth embodiment of the present invention, the P-polarized component of the ultraviolet light whose reflection intensity greatly depends on the temperature of the measurement object is measured so that the incident angle is in the vicinity of the Brewster angle. Since the temperature of the measurement object is calculated based on the reflected intensity of the reflected light, the surface condition of the wafer that is the temperature measurement object, that is, the error due to the thickness and physical properties of the oxide film has been reduced. Temperature measurement can be performed.

  The present invention can be used in a wafer temperature measuring method and apparatus used for controlling the temperature of a wafer in a semiconductor manufacturing process.

It is a graph showing the change rate of the reflection intensity of the P polarization component with respect to silicon. It is a graph which shows the reflectance of the S polarization component with respect to a silicon wafer. It is a graph which shows the reflectance of the P polarization component with respect to a silicon wafer. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 1st Embodiment of this invention. It is a block diagram for demonstrating the function of the signal processing part shown in FIG. It is a flowchart which shows the calibration method of the parameter in the 1st Embodiment of this invention. It is a flowchart which shows the calculation method of the temperature in the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the modification of the wafer temperature measuring apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 4th Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 5th Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 6th Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 7th Embodiment of this invention. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 8th Embodiment of this invention. It is a figure for demonstrating the parameter calibration method in the wafer temperature measuring apparatus which concerns on embodiment of this invention. It is a table | surface which shows the reflectance of the P polarization component and S polarization component with respect to a silicon oxide film. It is a graph which shows the incident angle dependence of the reflectance of the P polarization component and S polarization component with respect to a silicon oxide film. It is a schematic diagram which shows the structure of the wafer temperature measuring apparatus which concerns on the 9th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Calibration controller, 12 ... Wafer temperature instruction | indication part, 13 ... Calibration data storage part, 14 ... Calibration value calculation part, 15 ... Calibration parameter storage part, 21 ... Relative value calculation part, 22 ... Temperature calculation part, 23 ... Temperature signal Output unit, 100 ... wafer, 110, 210, 310, 510, 610, 710, 810, 910, 930 ... light source unit, 111, 211, 216, 311, 401, 511, 514, 611, 616, 620, 711, 811, 814, 911, 931, 936 ... Driving circuit (DR), 112, 212, 217, 312, 402, 512, 515, 612, 617, 621, 712, 812, 815, 912, 932, 937 ... Light source device (LS), 113, 213, 218, 313, 403, 513, 516, 613, 618, 622, 713, 813, 8 6, 913, 933, 938 ... collimating lens, 114, 214, 219, 334, 41, 42, 43, 934, 939 ... beam splitter, 115, 408, 518, 614, 619, 623, 832 ... polarizing element (polarizer) ), 116, 222, 519, 625 ... optical chopper, 117, 134, 136, 215, 220, 234, 237, 333, 336, 411, 534, 537, 736-739, 835, 924, 926, 935, 940 , 956, 958... Photodetector (PD), 121, 122... Prism, 130, 230, 330, 530, 730, 830, 920, 950 ... Light receiving part, 131, 232, 235, 314, 921. , 132, 221, 231, 531, 732, 733, 817, 922... Beam splitter (polarizing prism), 133, 135, 233, 236, 409, 532, 535 ... Condensing lens, 140 ... Signal amplifier (AMP), 150 ... Signal processing unit (PC), 223, 942 ... Light quantity comparison unit ( CMP), 320 ... chamber, 32, 33, 35, 36, 321, 324, 327 ... window, 322, 323, 351 ... heater, 325, 326 ... impurity-preventing cover, 31, 34 ... optical path passageway, 331 ... Wollaston prism, 332, 335, 410, 533, 536, 923, 925, 955, 957 ... integrating sphere, 337 ... position detection sensor, 340 ... support section, 341 ... mechanical stage, 342 ... autocollimator unit, 343 ... Mechanical stage drive unit (MTD), 350 ... rod, 404 ... aperture (opening), 405: Spectroscopic unit, 407, 831 ... Optical modulator, 412 ... Optical modulator driver (PCD), 517, 614, 624, 941 ... Wavelength synthesis element, 550 ... Wafer support, 561 ... Actuator, 562 ... Temperature sensor 563 ... Calibration test piece, 564 ... Arm, 565 ... Rotating motor, 70 ... Optical path passage, 71-73 ... Wavelength separation filter, 721 ... Wafer support, 731 ... Wavelength separation filter group, 722-724 ... Support member , 722a, 722b, 723a, 724a ... position adjusting unit, 734,833 ... diffusing plate, 735,834,951 ... lens, 760 ... position detecting unit, 761 ... condensing lens, 762 ... position detecting element, 952, 953 ... Aperture (opening), 954... Wavelength separation element

Claims (24)

A method of measuring a wafer temperature based on reflected light of light irradiated on a wafer that is a temperature measurement object,
(A) generating light containing a P-polarized component having a wavelength of 400 nm or less and irradiating the temperature measurement object;
Receiving the reflected light reflected by the temperature measurement object, and detecting at least the intensity of the P-polarized light component having a wavelength of 400 nm or less included in the reflected light;
Calculating the temperature of the temperature measurement object based on at least the intensity of the P-polarized component having a wavelength of 400 nm or less detected in step (b);
A wafer temperature measuring method comprising: The step (a) generates light including a P-polarized component having a wavelength of 400 nm or less and an S-polarized component having a wavelength of 400 nm or less, or a P-polarized component or S-polarized component having a wavelength longer than 400 nm, and the temperature measurement object. Including irradiating
Step (b) comprises detecting the intensity of an S-polarized component having a wavelength of 400 nm or less, or a P-polarized component or an S-polarized component having a wavelength longer than 400 nm,
Step (c) uses the intensity of the P-polarized light component having a wavelength of 400 nm or less as the detection value, and the intensity of the S-polarized light component having a wavelength of 400 nm or less, or the intensity of the P-polarized light component or S-polarized light component having a wavelength longer than 400 nm as the reference value Calculating the temperature of the temperature measurement object,
The wafer temperature measuring method according to claim 1. A method of measuring a wafer temperature based on reflected light of light irradiated on a wafer that is a temperature measurement object,
Irradiating the temperature measurement object with light containing a wavelength component of 400 nm or less and light containing a wavelength component greater than 400 nm;
Receiving light reflected by the temperature measurement object, (i) the intensity of the P-polarized component having a wavelength of 400 nm or less, (ii) the intensity of the P-polarized component having a wavelength of more than 400 nm, and (iii) the wavelength of 400 nm or less Detecting at least one of the intensity of the S-polarized light component and the intensity of the S-polarized light component having a wavelength greater than 400 nm;
The relative value of the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of any S-polarized component, and the relative value of the intensity of the P-polarized component having a wavelength greater than 400 nm and the intensity of any S-polarized component And (c) performing an operation for correcting an error due to the film formed on the wafer surface,
A wafer temperature measuring method comprising:   In step (c), the relative value between the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the S-polarized component having a wavelength of 400 nm or less, and the intensity and wavelength of the P-polarized component having a wavelength of greater than 400 nm are greater than 400 nm. 4. The wafer temperature measuring method according to claim 3, comprising correcting the error based on a relative value with the intensity of the polarization component. A method of measuring a wafer temperature based on reflected light of light irradiated on a wafer that is a temperature measurement object,
Irradiating the temperature measurement object with light containing a wavelength component of 400 nm or less and light containing a wavelength component larger than 400 nm so that the incident angle falls within a predetermined range including the Brewster angle;
Receiving the light reflected by the temperature measurement object, detecting the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the P-polarized component having a wavelength of greater than 400 nm (b);
Calculating the temperature of the temperature measurement object based on the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the P-polarized component having a wavelength of greater than 400 nm detected in step (b); ,
A wafer temperature measuring method comprising:   Step (a) includes irradiating the temperature measurement object with light containing a wavelength component of 400 nm or less and light containing a wavelength component of more than 400 nm so that the incident angle is 45 ° or more and 60 ° or less. The wafer temperature measuring method according to claim 5. Incident angle of light including a P-polarized component having a wavelength of 400 nm or less and an S-polarized component having a wavelength of 400 nm or less, or a light having a P-polarized component or S-polarized component having a wavelength of greater than 400 nm so as to be larger than the Brewster angle. Irradiating the temperature measurement object to (a2),
The light irradiated in step (a2) receives the light reflected by the temperature measurement object, the intensity of the P-polarized component having a wavelength of 400 nm or less, and the S-polarized component having a wavelength of 400 nm or less or the wavelength is greater than 400 nm. Detecting the intensity of the P-polarized component or S-polarized component (b2);
Further comprising
Step (c) is detected in step (b), the intensity of the P-polarized component having a wavelength of 400 nm or less, and the intensity of the P-polarized component having a wavelength of greater than 400 nm, and the wavelength detected in step (b2) Calculating the wafer temperature based on the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the S-polarized component having a wavelength of 400 nm or less, or the intensity of the P-polarized component or S-polarized component having a wavelength of greater than 400 nm.
The wafer temperature measuring method according to claim 5 or 6.   In step (b2), light including a P-polarized component having a wavelength of 400 nm or less and an S-polarized component having a wavelength of 400 nm or less or a P-polarized component having a wavelength greater than 400 nm or S so that the incident angle is greater than 60 ° The wafer temperature measuring method according to claim 7, comprising irradiating the temperature measuring object with light containing a polarization component. An apparatus for measuring a wafer temperature based on reflected light of light irradiated to a temperature measurement target wafer,
A light irradiation means for generating light including a P-polarized component having a wavelength of 400 nm or less and irradiating the temperature measurement object;
Light receiving means for receiving reflected light reflected by the temperature measurement object and detecting at least the intensity of a P-polarized light component having a wavelength of 400 nm or less included in the reflected light;
A computing means for calculating the temperature of the temperature measurement object based on the intensity of the P-polarized component having a wavelength detected by the light receiving means of 400 nm or less;
A wafer temperature measuring apparatus comprising: The light irradiation means includes a light source that generates light having a wavelength of 400 nm or less, and an optical system that guides the light generated from the light source to the temperature measurement target,
A polarizing element for separating the received light into a P-polarized component and an S-polarized component; and a plurality of light detecting means for detecting the intensities of the P-polarized component and the S-polarized component separated by the polarizing element, respectively. Including
The calculation means calculates the temperature of the temperature measurement object by using the intensity of the P-polarized component detected by the plurality of light detection means as a detection value and the intensity of the S-polarization component as a reference value.
The wafer temperature measuring apparatus according to claim 9. The light irradiating means includes a first light source that generates light having a wavelength of 400 nm or less, a second light source that generates light having a wavelength longer than 400 nm, and a P-polarized component of light emitted from the first light source; An optical system that guides the P-polarized component or the S-polarized component of the light emitted from the second light source to the temperature measurement object,
The light receiving means separates the received light according to the wavelength or polarization direction, the P polarized component having a wavelength of 400 nm or less and the P polarized component having a wavelength longer than 400 nm or S separated by the spectral means. A plurality of light detection means for detecting the intensity of each polarization component,
The computing means uses the intensity of the P-polarized component having a wavelength of 400 nm or less detected by the plurality of light detecting means as a detection value, and uses the intensity of the P-polarized component or S-polarized component having a wavelength longer than 400 nm as a reference value. By calculating the temperature of the temperature measurement object,
The wafer temperature measuring apparatus according to claim 9. The light irradiation means includes a light source that generates light having a wavelength of 400 nm or less, and an optical system that guides the light generated from the light source to the temperature measurement target,
The light receiving means receives light through the light modulating means for changing the polarization direction of the received light at predetermined time intervals, a polarizing element that transmits a predetermined polarization component, and the light modulating means and the polarizing element. A light detecting means for detecting in a time-division manner the intensity of the P-polarized component and the S-polarized component contained in the light reflected by the temperature measurement object,
The calculation means calculates the temperature of the temperature measurement object by setting the intensity of the P-polarized component detected by the light detection means as a detection value and the intensity of the S-polarization component as a reference value.
The wafer temperature measuring apparatus according to claim 9. An apparatus for measuring a wafer temperature based on reflected light of light irradiated to a temperature measurement target wafer,
Light irradiation means for irradiating the temperature measurement object with light containing a wavelength component of 400 nm or less and light containing a wavelength component of greater than 400 nm;
Receiving the light reflected by the temperature measurement object, (i) the intensity of the P-polarized component having a wavelength of 400 nm or less, (ii) the intensity of the P-polarized component having a wavelength of more than 400 nm, and (iii) the wavelength of 400 nm or less. Light receiving means for detecting at least one of the intensity of the S-polarized light component and the intensity of the S-polarized light component having a wavelength greater than 400 nm;
The relative value of the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of any S-polarized component, and the relative value of the intensity of the P-polarized component having a wavelength greater than 400 nm and the intensity of any of the S-polarized components Calculation means for performing an operation for correcting an error due to the film formed on the wafer surface,
A wafer temperature measuring apparatus comprising: The light irradiation means includes a first light source that generates light having a wavelength of 400 nm that operates in a time-sharing manner, and a second light source that generates light having a wavelength greater than 400 nm,
The light receiving means separates the received light into a P-polarized component and an S-polarized component, a first light detecting means for detecting the intensity of the P-polarized component separated by the separating means, Second light detection means for detecting the intensity of the S-polarized component separated by the separation means,
(I) the intensity of the P-polarized component having a wavelength of 400 nm or less detected by time division by the first light detecting means, (ii) the intensity of the P-polarized component having a wavelength greater than 400 nm, and (iii) ) Calculation is performed based on at least one of the intensity of the S-polarized light component having a wavelength of 400 nm or less detected by the second light detection means and the intensity of the S-polarized light component having a wavelength of greater than 400 nm.
The wafer temperature measuring apparatus according to claim 13. The light irradiation means includes a light source that generates light including a wavelength component of 400 nm or less and a wavelength component of greater than 400 nm;
The light receiving means includes a first separation means for separating received light into a wavelength component of 400 nm or less and a wavelength component of greater than 400 nm; a wavelength component of 400 nm or less and a wavelength component of greater than 400 nm separated by the separation means; A plurality of second separation means for separating each of them into a P-polarized component and an S-polarized component; and a plurality of light detection means for detecting the intensities of the plurality of components separated by the plurality of second separation means, respectively. Including
(I) the intensity of the P-polarized component having a wavelength of 400 nm or less, (ii) the intensity of the P-polarized component having a wavelength greater than 400 nm, and (iii) the wavelength detected by the computing means. Is calculated based on at least one of the intensity of the S-polarized component having a wavelength of 400 nm or less and the intensity of the S-polarized component having a wavelength of greater than 400 nm.
The wafer temperature measuring apparatus according to claim 13. The light irradiation means includes a first light source that generates light having a wavelength of 400 nm that operates in a time-sharing manner, and a second light source that generates light having a wavelength greater than 400 nm,
The light receiving means receives light through the light modulating means for changing the polarization direction of the received light at predetermined time intervals, a polarizing element that transmits a predetermined polarization component, and the light modulating means and the polarizing element. And a light detection means for detecting, in a time division manner, the intensity of the P-polarized component and the S-polarized component contained in the light reflected by the temperature measurement object,
(I) the intensity of the P-polarized component having a wavelength of 400 nm or less detected by time division by the light detecting means, (ii) the intensity of the P-polarized component having a wavelength greater than 400 nm, and (iii) the wavelength. Is calculated based on at least one of the intensity of the S-polarized light component having a wavelength of 400 nm or less and the S-polarized light component having a wavelength of greater than 400 nm.
The wafer temperature measuring apparatus according to claim 13. An apparatus for measuring a wafer temperature based on reflected light of light irradiated to a temperature measurement target wafer,
Light irradiating means for irradiating the temperature measurement object with light including a wavelength component of 400 nm or less and light including a wavelength component greater than 400 nm so that the incident angle is within a predetermined range including the Brewster angle;
Light receiving means for receiving light reflected by the temperature measurement object and detecting the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the P-polarized component having a wavelength of greater than 400 nm;
Arithmetic means for calculating the temperature of the temperature measurement object based on the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the P-polarized component having a wavelength of greater than 400 nm detected by the light receiving means;
A wafer temperature measuring apparatus comprising:   The light measurement unit irradiates the temperature measurement object with light containing a wavelength component of 400 nm or less and light containing a wavelength component of more than 400 nm so that the incident angle is 45 ° or more and 60 ° or less. 18. The wafer temperature measuring device according to 17. Incident angle of light including a P-polarized component having a wavelength of 400 nm or less and an S-polarized component having a wavelength of 400 nm or less or a P-polarized component or S-polarized component having a wavelength of greater than 400 nm so that the incident angle is larger than the Brewster angle. A second light irradiating means for irradiating the temperature measurement object;
The light irradiated by the second light irradiating means receives the light reflected by the temperature measurement object, the intensity of the P-polarized component having a wavelength of 400 nm or less, and the S-polarized component or wavelength having a wavelength of 400 nm or less. A second light receiving means for detecting the intensity of the P-polarized light component or S-polarized light component greater than 400 nm;
Further comprising
The arithmetic means detects the intensity of the P-polarized component having a wavelength of 400 nm or less detected by the first light-receiving means and the intensity of the P-polarized component having a wavelength greater than 400 nm, and is detected by the second light-receiving means. The wafer temperature is calculated based on the intensity of the P-polarized component having a wavelength of 400 nm or less and the intensity of the S-polarized component having a wavelength of 400 nm or less, or the intensity of the P-polarized component or S-polarized component having a wavelength of greater than 400 nm.
The wafer temperature measuring apparatus according to claim 17 or 18.   The second light irradiation means includes light including a P-polarized component having a wavelength of 400 nm or less and an S-polarized component having a wavelength of 400 nm or less or P-polarized light having a wavelength of greater than 400 nm so that the incident angle is greater than 60 °. The wafer temperature measuring apparatus according to claim 19, wherein the temperature measuring object is irradiated with light containing a component or an S-polarized component. The first or second light irradiation means comprises:
A light source device for emitting ultraviolet light;
A drive circuit for controlling the operation of the light source device;
A collimating lens that forms a parallel beam by transmitting an ultraviolet light source emitted from the light source device;
A beam splitter for splitting the parallel beam to guide a part of the parallel beam to the temperature measurement object;
An optical chopper that chops the parallel beam guided to the temperature measurement object by the beam splitter at a predetermined timing or frequency;
21. The wafer temperature measuring apparatus according to claim 9, further comprising a photodetector that detects another part of the parallel beam divided by the beam splitter. The light receiving means is
A wavelength selection filter that transmits a predetermined wavelength component of ultraviolet light reflected from the measurement object;
A polarizing beam splitter that separates the ultraviolet light transmitted through the wavelength selective filter into a P-polarized component and an S-polarized component;
A first condensing lens that condenses the P-polarized component separated by the polarizing beam splitter at a predetermined position;
A first photodetector for detecting a P-polarized component collected by the first condenser lens;
A second condensing lens that condenses the S-polarized component separated by the polarizing beam splitter at a predetermined position, and a second light detection that detects the S-polarized component collected by the first condensing lens. And
The wafer temperature measuring apparatus according to claim 9, comprising: A signal amplifier for amplifying at least a signal representing the intensity of the P-polarized component having a wavelength of 400 nm or less, which is detected by the light receiving means, and which is included in the reflected light;
The calculation means calculates the temperature of the temperature measurement based on the signal amplified by the signal amplifier,
The wafer temperature measuring apparatus according to any one of claims 9 to 22. A first prism for guiding light generated from the light irradiation means to the temperature measurement object;
A second prism for guiding light reflected from the temperature measurement object to the light receiving means;
The wafer temperature measuring apparatus according to claim 9, further comprising:

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