JPH0599751A - Method for measuring infrared radiation temperature - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the measurement accuracy of infrared radiation temperature measurement methods. [Structure] The radiated light 31 from the substrate 2 is split into visible light 32 and infrared light 33, and the hood is adjusted by the amount of attenuation of the visible light 32.
The reflectance of the reflecting mirror 29 provided in 15 is evaluated, and thereby the substrate temperature using the infrared light 33 is corrected, and the contamination state of the reflecting mirror 29 is managed. A shutter 30 that opens and closes the opening of the hood 15 is provided, the reference light reflected by the shutter 30 that closes the opening is used to measure the variation in the reflectance of the reflecting mirror 29 provided on the hood 15, and the information is Based on this, the substrate temperature using the emitted light 31 is corrected, and the contamination state of the reflecting mirror 29 is managed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to temperature control of a substrate to be vacuum processed, and more particularly to an infrared radiation temperature measuring method for controlling the substrate temperature in a vacuum film forming process.

[0002]

2. Description of the Related Art Infrared radiation temperature measuring methods have been used for several years as a substrate temperature measuring method in a film forming process. In particular, as a recently developed radiation thermometer, an in-vacuum measuring device disclosed in JP-A-1-107120, JP-A-2
There is a temperature measuring device disclosed in JP-A-307026.

FIG. 8 is a principle diagram of an in-vacuum measuring device disclosed in Japanese Patent Laid-Open No. 1-107120. Reference numeral 1 is a vacuum chamber, 2 is a substrate to be vacuum-processed (formed) in the vacuum chamber 1, and 3 is infrared detection. Probe, 4 is an infrared radiation thermometer, 5 is an arm for moving the probe 3, 6 is a flexible metal tube (bellows tube) whose one end is hermetically joined to the probe 3, and 7 is the probe 3 at one end.
An optical fiber 8 connected to the metal tube 6, a metal fitting 8 joined to the middle portion of the metal tube 6, and an O-ring 9 for hermetically bonding the outer wall of the vacuum chamber 1 and the metal fitting 8 together.

In such a device, the probe 3 and the infrared radiation thermometer 4 are connected by the optical fiber 7 having a good infrared transparency, and the probe 3 can be brought close to the substrate 2 when the temperature of the substrate 2 is measured. The temperature measurement is more accurate than that of the previous apparatus, and the contamination of the probe 3 by the film-forming scattered particles can be reduced. Further, as described in the embodiment, an L-shaped hood is provided at the tip of the probe 3 and a reflecting mirror is provided at a bent portion of the hood so that infrared rays emitted from the substrate 2 are reflected by the reflecting mirror and enter the probe 3. By doing so, the contamination of the probe 3 is further reduced.

The temperature measuring device disclosed in Japanese Patent Application Laid-Open No. 2-307026 collects infrared rays emitted from an object (substrate) and guides the collected infrared rays to the outside of the vacuum chamber through an optical fiber. As an optical fiber, germanium, arsenic,
Using chalcogen fiber with selenium and tellurium as the composition, mercury, cadmium, and
It is characterized by using tellurium as a composition.

[0006]

In the prior art of detecting infrared rays radiated from a film-forming substrate and detecting the temperature of the substrate relating to the film-forming characteristics, the infrared-detecting probe is brought close to the substrate only when measuring the substrate temperature. Further, by providing the probe with the L-shaped hood having the reflecting mirror provided on the bent portion, the infrared ray detection probe (lens) is less likely to be contaminated by the film-forming scattered particles.

As shown in FIG. 9, in order to avoid the influence of the temperature rise of the probe during film formation, an in-line type double-sided sputtering apparatus in which the probe is cooled is taken as an example. In FIG. 9 used, 10 is a holder for holding the central part of the substrate 2, and 11 is 180
An arm that rotates once, 12 is a mechanism that rotates the arm 11,
13 is a sputtering target, 14 is a mechanism for cooling the target 13, 15 is an L-shaped hood provided at the tip of the probe 3, 16 is a cooling pipe for cooling the probe 3 and the hood 15, and 17 is a cooling pipe 16. A flowing refrigerant cooler, 18 is a flexible metal tube (bellows) through which the optical fiber 7 and the cooling tube 16 are inserted, and 19 is a shield plate for preventing film-forming particles from adhering to the probe 3 and the rotation mechanism section 12. A part of the cooling pipe 16 for cooling the probe 3 is wound around the hood 15,
And cool the reflector (not shown) in the hood 15.

However, in such a device, when the substrate 2 is replaced or when the substrate 2 is not set due to pre-sputtering or the like, particles scattered from the target 13 enter the hood 15 and the hood 15
The reflector in 15 had a problem that it was contaminated and its life was shortened.

Further, in the conventional method, a transparent film such as an oxide is adhered to the reflecting mirror in the hood, and a decrease in reflectance of the reflecting mirror is unavoidable. Therefore, when a film-forming reflecting mirror having a low reflectance is used, there is a problem that the measurement accuracy is greatly affected by the decrease in the infrared ray amount due to the reflecting mirror when measuring in a low temperature range of about 100 ° C. or less.

In addition, conventionally, in order to check the contamination state of the reflecting mirror, it is necessary to stop the apparatus and remove the reflecting mirror to carry out the investigation, and there is an uncertainty that the replacement time depends on experience. It was

[0011]

FIG. 1 shows a first method of the present invention.
The basic diagram (a) and the second basic diagram (b). In FIG. 1, 2 is a film forming substrate, 3 is an infrared detection probe, 7 is an optical fiber led from the probe 3, 15 is an L-shaped hood provided at the tip of the probe 3, 29 is a reflecting mirror provided on the L-shaped hood, 20 is a spectroscope, 21 is a visible light detector, 22 is an infrared light detector, 23 is a temperature converter, 24 is a controller, 25 is a collimator lens, 26 is an optical path switching reflecting mirror, and 27 is reference light. It is a device.

A reflecting mirror provided in the middle of the optical system (see FIG. 1B)
When measuring the amount of radiated light (temperature of substrate 2) radiated from the film formation substrate 2 via 29), the decrease in reflectance of the reflecting mirror caused by contamination of the reflecting mirror is caused by infrared rays included in the radiating light. In Fig. 1 (a), which utilizes the fact that the visible light contained in the emitted light is significantly reduced compared to the light reduction, the detected light (radiated light from the substrate) 31 emitted from the optical fiber 7 is converted into visible light 32 by the spectroscope 20. And split into infrared light 33.

The detector 21 for detecting the visible light 32 is connected to the controller 24. The detector 22 that detects the infrared light 33 is connected to a temperature converter 23 that converts the amount of the infrared light 33 into a temperature, and the converter 23 is connected to a controller 24. For example, the controller 24 using a personal computer calculates the contamination state of the reflecting mirror based on the signal change from the detector 21, and corrects the substrate temperature based on the contamination state of the reflecting mirror (decrease in reflectance).

In FIG. 1B, in which reference light is used to detect the reflectance of the reflecting mirror, the hood 15 joined to the tip of the probe 3 is L-shaped, and a reflecting mirror 29 is provided at its bent portion.
A shutter 30 that can open and close the open end of the hood 15 is provided between the substrate 2 and the hood 15. Derivation end of optical fiber 7
The collimator lens 25 faces the right end.

When measuring the temperature of the substrate 2 from the radiant light 31 emitted from the substrate 2, a rotatable reflecting mirror 26 and a shutter are provided.
30 is in the open state, so the emitted light 31 is an infrared detector
The temperature converter 23 outputs the temperature of the substrate 2 according to the amount of light output from the detector 22 after entering the detector 22.

On the other hand, when investigating the contamination (reflectance) of the reflecting mirror 29, the reflecting mirror 26 and the shutter 30 are closed as shown by the solid line, and the reference light 34 emitted from the light source 28a of the reference light device 27 is
The light is reflected by the reflecting mirror 26, passes through the collimator lens 25, the optical fiber 7, the probe 3, and the hood 15, and is reflected by the reflecting mirror 29 to irradiate the shutter 30. The reference light 34 reflected by the shutter 30 is reflected by the reflecting mirror 29, passes through the hood 15, the probe 3, the optical fiber 7, the collimator lens 25, and is reflected by the reflecting mirror 26, and the reflectance measuring device 28 b of the reference light device 27. Then, the reflectance of the reflecting mirror 29 is measured.

[0017]

The first means of the method of the present invention shown in FIG. 1 (a) is the reflectance of the reflecting mirror in the middle of the optical path when the emitted light from the vacuum-processed substrate is divided into visible light and infrared light. This is because the change is more noticeable in visible light than in infrared light.
By detecting the reflectance decrease of the reflector using visible light, it is possible to know the replacement time of the reflector more accurately than the method of detecting the reflectance decrease of the reflector using infrared light. It is possible to correct the substrate temperature measurement value by reducing the reflectance of the mirror, and the reflectance measurement of the reflecting mirror is more accurate than before, and the reflectance measurement can be performed while measuring the temperature.

The second above-mentioned means of the method of the present invention shown in FIG. 1 (b) is to close the opening of the hood with a shutter whose condition can be made more constant than that of the vacuum-processed substrate, and to provide the shutter with high reflectance and the reference light. The device is used to measure the reflectance of the reflector in the middle of the optical path.By using a high-reflectance shutter, the reflectance of the reflector is more stable than the method that uses the radiation from the processing substrate. Can be made more accurate.

[0019]

FIG. 2 is a schematic configuration diagram of a film forming apparatus according to the first embodiment of the present invention. In FIG. From a tray (not shown) containing 20 substrates, the substrates 2 are carried one by one to the left holder 10 and held by a handling arm (not shown).

Then, when the arm 11 rotates 180 degrees, the substrate 2 held by the left holder 10 comes to be positioned between the pair of targets 13 facing each other, and a predetermined film is formed on the surface thereof. The holder 10 is rotatable while holding the substrate 2 therebetween, and therefore the film deposited on the surface of the substrate 2 has a uniform thickness.

The target 13 is cooled by the target cooling mechanism 14, and the substrate 2 on which the film has been formed is returned to the tray by the handling arm as the arm 11 further rotates 180 degrees.

Outside the vacuum chamber 1, a spectroscope 20 connected to the probe 3 via an optical fiber 7 and having an infrared light detector and a visible light detector built therein, and a temperature converter (infrared ray) connected to the spectroscope 20. A thermometer 23, a controller 24 connected to the spectroscope 20 and the converter 23, and a cooler 17 for cooling the probe 3 and the hood 15 are provided. In the figure, 8 is a metal tube 18
Is an airtightly joined metal fitting, and 9 is an O-ring for ensuring airtightness between the outer wall of the vacuum chamber 1 and the metal fitting 8.

FIG. 3 is a block diagram for explaining the method of correcting the measured temperature in the apparatus of the first embodiment, and FIG. 4 is a spectroscopic analyzer for the reflectance of an aluminum reflecting mirror coated (contaminated) by Co Cr sputtering. Measured data, FIG. 5 is a diagram showing the relationship between the reflectance variation of visible light and the reflectance variation of infrared light. The method for correcting the measured temperature in the apparatus shown in FIG. 2 using FIGS. 3 to 5. Will be explained.

In FIG. 3 in which the same reference numerals are used for the same parts as in the above-mentioned drawing, 2 is a film-forming substrate, 3 is a probe, 15 is an L-shaped hood, 29 is a reflecting mirror provided in the bent portion of the hood 15, and 7 is An optical fiber, 25 a collimator lens, 20 'a spectral prism, 35 a visible light filter, 36 an infrared light filter, 21 a visible light detector, 22 an infrared light detector, and 23 an infrared light quantity. A temperature converter for converting the temperature, 24 is a controller for performing arithmetic processing such as temperature correction and outputting the corrected temperature of the substrate. The prism 20 ', the filters 35 and 36, and the detectors 21 and 22 are housed in the spectroscope 20 in FIG.

In FIG. 4, the vertical axis represents the reflectance (%) of the reflecting mirror, the horizontal axis represents the wavelength (nm), the curve A shown by the solid line in the figure is the reflectance characteristic of the aluminum reflecting mirror, and the broken line in the figure. The curve B shown is the reflectance characteristic when an aluminum reflector is coated with Co Cr sputtering to a thickness of several 10 Å.

Comparing characteristics A and B, the wavelength of light is 1500 nm
The difference is slight in the infrared region above a certain level and almost overlaps, but the difference becomes clear in the visible region below about 1500 nm, especially below about 800 nm. Therefore, if the reflectance of the reflecting mirror is measured at a visible wavelength of about 800 nm or less, it becomes possible to detect reflectance fluctuations that are difficult to detect by measurement using infrared light.

In FIG. 5, the vertical axis represents the change rate of the reflectance of infrared light (λ ₂ ) with respect to the aluminum reflecting mirror, and the horizontal axis represents the change rate of the reflectance of visible light (λ ₁ ) with respect to the aluminum reflecting mirror. That is, the measurement data is obtained by previously investigating the reflectance variation due to the contamination state of the reflecting mirror 29. However, the reflectance of visible light with respect to a clean reflecting mirror is represented by σ ₁ , and the reflectance of infrared light with respect to a clean reflecting mirror is σ ₂ , and the reflectance of visible light with respect to a reflecting mirror contaminated by a certain coating is shown. Assuming that the reflectance is σ ₁₁ , and the reflectance of infrared light is σ ₁₂ for a contaminated reflector, the change in reflectance of infrared light is σ ₁₂ / σ ₂ ,
The change in reflectance of visible light is σ ₁₁ / σ ₁ .

Returning to FIG. 3 again, the emitted light 31 from the substrate 2 at the temperature T ₁ is reflected by the reflecting mirror 29, detected by the probe 3, passes through the optical fiber 7 and enters the prism 20 '. prism
20 ′ divides the emitted light 31 into visible light 32 and infrared light 33, visible light 32 that has passed through the filter 35 enters the detector 21, and infrared light 33 that has passed through the filter 36 enters the detector 22. The temperature is output by the temperature converter 23 connected to the detector 22, and T ₁ is obtained by setting the emissivity of the substrate 2.

Therefore, the visible light output from the detector 21 is set to Pc,
Let infrared light output from the detector 22 be pc, the temperature of the substrate 2 at a certain time point is T ₂ , and then the output of the converter 23 is T ₂ ′,
Assuming that the output of visible light is pc and the output of infrared light is pi, they have the following relationships.

[0030]

[Equation 1]

[0031]

[Equation 2] Here, if the ratios of the formula and the formula are equal,

[0032]

[Equation 3] Is established, which means that

[0033]

[Equation 4] Is shown. In other words, the fact that the ratios of the formulas are equal means that the reflecting mirror 29 does not have a coating that impairs its reflectivity, and from the formula,

[0034]

[Equation 5] Therefore, the display T _{2 on the} thermometer is correct. On the other hand, if the reflecting mirror 29 is coated with a film that impairs its reflectance,

[0035]

[Equation 6] Therefore, from the formula, the formula,

[0036]

[Equation 7] Is established. In the equation, when the left side is found by measurement, the reflectance ratio on the right side is known, each value is determined from FIG. 5, and when σ ₁₁ / σ ₁ and σ ₁₂ / σ ₂ are found, the true substrate temperature T ₂ is obtained from the expression. Is

[0037]

[Equation 8] It is represented by. By repeating the temperature correction by the controller (for example, a personal computer) 24, it is possible to continuously and accurately measure the temperature and to detect the change with time of the reflectance of the reflecting mirror 29, and based on the information, the reflecting mirror can be detected.
29 replacement times can be determined.

FIG. 6 is a schematic configuration diagram of a film forming apparatus according to the second embodiment of the present invention, and FIG. 7 is a configuration diagram for explaining a reflectance measuring method of a reflecting mirror in the apparatus of the second embodiment. In FIG. 6, where the same reference numerals are used for the same parts as in the previous figure, the in-line type double-sided sputtering apparatus uses a tray (not shown) containing 20 substrates, one by one by a handling arm (not shown). Board 2 is holder 10 on the left side
It will be carried and pinched.

Then, when the arm 11 rotates 180 degrees, the substrate 2 held by the left holder 10 comes to be positioned between the pair of targets 13 facing each other, and a predetermined film is formed on the surface thereof. The holder 10 is rotatable while holding the substrate 2 therebetween, and therefore the film deposited on the surface of the substrate 2 has a uniform thickness.

The target 13 is cooled by the target cooling mechanism 14, and the substrate 2 on which the film has been formed is returned to the tray by the handling arm as the arm 11 further rotates 180 degrees.

Outside the vacuum chamber 1, a reference light device 27 connected to the probe 3 via an optical fiber 7, a temperature converter (infrared thermometer) 2 for detecting the temperature of the substrate 2 by radiated light 2
3. A controller 24 and a cooler 17 for cooling the probe 3 and the hood 15 are provided. In the figure, 8 is a metal fitting in which the metal tube 18 is airtightly joined, and 9 is an O-ring for ensuring airtightness between the outer wall of the vacuum chamber 1 and the metal fitting 8.

In FIG. 7, in which the same reference numerals are used for the same parts as in the previous figure, the shutter 30 closes the opening surface of the hood 15, and the rotatable reflecting mirror 26 is inclined at 45 degrees as shown by the solid line to emit the radiated light. The detection unit 40 is shut off. The radiant light detector 40 includes a temperature converter 23, a chopper 23a, and a filter 23b.

The reference light device 27 includes a light source 28a and a reflectance measuring device.
28b, beam splitter 28c, and shutter 26,
The reference light 34 emitted from the light source 28a is a beam splitter 28c,
The light is reflected by the reflecting mirrors 26 and 29 and is applied to the shutter 30.

Reference light 34 emitted from the shutter 30 and reflected
Is reflected by the reflecting mirror 29 and the reflecting mirror 26, and the beam splitter 28
After passing through c, it enters the reflectance measuring device 28b. So the reflector 2
Assuming that the output of the reflectance measuring instrument 28b when 9 is in a clean state is P ₁ and the output of the reflectance measuring instrument 28b when the reflecting mirror 29 is contaminated to some extent is P ₂ The rate of decrease of the rate is represented by (P ₂ / P ₁ ) ^1/2 .

When the reflectance of the reflecting mirror 29 decreases, an error occurs in the temperature measurement of the substrate 2, and it is necessary to correct it. Therefore, the emissivity is ε, and the reflectance change of the reflecting mirror 29 is σ '(= (P ₂ / P ₁ )
^1/2 ), the corrected emissivity ε'is

[0046]

[Equation 9] It is represented by. By feeding back this corrected emissivity ε'to the temperature converter 23 by the controller 24, a highly accurate temperature measurement value can be obtained.

Therefore, the output of the reflectance measuring instrument 28b when the reflecting mirror 29 is in a clean state is P _1, and the output of the reflectance measuring instrument 28b when the reflecting mirror 29 is contaminated to some extent is P _2. , If the reflectance of the reflecting mirror 29 changes from σ _{1 to} σ ₂ , the following relationship holds between them.

[0048]

[Equation 10] Therefore, the amount of energy that infrared rays emitted from the substrate 2 enter the converter 23 due to the contamination of the reflecting mirror 29 is E ₁ → E ₂
Then, the decrease in the reflectance of the reflecting mirror 29 results in E ₁
Therefore, the formula is

[0049]

[Equation 11] Becomes Next, the radiance is L ₁ (λ, T ₁ ) → L ₂ (λ, T
₂ ), E ₁ and E ₂ are defined as E ₁ and E ₂ when the emissivity of the substrate when a clean reflecting mirror 29 is used is ε ₁ .

[0050]

[Equation 12] Becomes If the emissivity corrected to the display temperature T ₁ when the amount of energy entering the converter 23 is E ₂ is ε ₂ ,

[0051]

[Equation 13] Is established. Therefore, the new emissivity to be set is

[0052]

[Numerical equation 14] Will be represented by Therefore, when the reflectance of the reflecting mirror 29 decreases, an error occurs in the temperature measurement of the substrate 2, and it is necessary to correct it. Therefore, the emissivity is ε and the reflectance of the reflecting mirror 29 changes σ.
_{If 2} / σ ₁ = σ ′, the corrected emissivity ε ₂ is

[0053]

[Equation 15] By feeding back the corrected emissivity ε ₂ to the temperature converter 23 by the controller 24, a highly accurate temperature measurement value can be obtained.

[0054]

As described above, according to the method of the present invention, the visible light or the visible light dispersed from the radiated light of the processed substrate,
By using a reference light different from the emitted light from the processing substrate, by measuring the reflectance decrease of the reflecting mirror provided in the hood, it is possible to correct the substrate temperature measurement value due to the reflectance change of the reflecting mirror, With the conventional method, the measurement error, which has increased with the coating (contamination) of the reflecting mirror, can be maintained below ± 3 ° C, and the renewal time of the reflecting mirror can be predicted, facilitating maintenance. There is an effect.

[Brief description of drawings]

FIG. 1 is first and second basic diagrams of the method of the present invention.

FIG. 2 is a schematic configuration diagram of a film forming apparatus according to a first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a method of correcting the measured temperature in the device according to the first embodiment.

FIG. 4 is data obtained by measuring the reflectance of an aluminum reflecting mirror coated by Co Cr sputtering with a spectroscopic analyzer.

FIG. 5 is a relational diagram of a reflectance change of a reflecting mirror relating to visible light and infrared light.

FIG. 6 is a schematic configuration diagram of a film forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram illustrating a method of measuring the reflectance of a reflecting mirror in the second embodiment device.

FIG. 8 is a principle diagram of a conventional vacuum chamber substrate temperature measuring device.

FIG. 9 is a schematic configuration diagram of a conventional film forming apparatus including a probe cooling unit.

[Explanation of symbols]

 2 is a vacuum processing substrate (deposition substrate) 3 is a radiant light detection probe 7 is an optical fiber 15 is an L-shaped hood 21,22 is a light amount detector 23 is a temperature converter for converting the light amount into temperature 24 is a controller 26 is an optical path switching The movable reflector 27 is the reference light device 28a is the reference light source 28b is the reflected reference light measuring instrument 29 is the reflector provided on the hood 30 is the hood shutter 31 is the light emitted from the substrate 32 is the visible light 33 is the infrared light 34 is the reference beam

Claims (4)

[Claims] 1. A radiant light (31) emitted from a substrate (2) processed in a vacuum chamber is connected to a radiant light detecting probe (3) and the radiant light detecting probe (3) provided in the vacuum chamber. The synchrotron radiation
A hood (15) having a reflecting mirror (29) for reflecting (31) toward the radiation detection probe (3), the radiation detection probe
Optical fiber connected to (3) and led out of the vacuum chamber (7)
At the outside of the vacuum chamber, the emitted light (31) sent from the outer end surface of the optical fiber (7) is split into visible light (32) and infrared light (33), The temperature of the substrate is measured by detecting the light amount of the light (33), and the decrease in the reflectance of the reflecting mirror (29) is evaluated by detecting the light amount of the visible light (32) and the attenuation thereof. Characteristic infrared radiation temperature measurement method. 2. The temperature measurement value of the substrate (2) utilizing the infrared light (33) is corrected by decreasing the reflectance of the reflecting mirror (29). Infrared radiation temperature measurement method. 3. A radiation light (31) emitted from a substrate (2) processed in a vacuum chamber is connected to a radiation light detection probe (3) and the radiation light detection probe (3) provided in the vacuum chamber. The synchrotron radiation
A hood (15) having a reflecting mirror (29) for reflecting (31) toward the emitted light detecting probe (3), the emitted light detecting probe
An optical fiber (7) connected to (3) and led out from the vacuum chamber,
Taken out of the vacuum chamber through the optical fiber (7),
In an apparatus for measuring the temperature of the substrate (2) from the radiated light (31), a shutter (30) for opening and closing the opening of the hood (15) facing the substrate (2), and the optical fiber (7) And the shutter (30) with the opening closed via the probe (3) and
A reference light device (27) for irradiating the reference light (34) with the light source (28a) for emitting the reference light (34) and the reference to the shutter (30). The reflected light measuring unit (28b) for measuring the amount of reflected light when irradiated with the light (34) is provided.
A method for measuring infrared radiation temperature, which comprises evaluating a decrease in reflectance of the reflecting mirror (29) according to the amount of attenuation of the reflected light of (34). 4. The substrate temperature measurement value is corrected using the emitted light (31) of the substrate (2) by reducing the reflected light of the reference light (34). Infrared radiation temperature measurement method.