JP4553308B2 - Temperature / thickness measuring device, temperature / thickness measuring method, temperature / thickness measuring system, control system, control method - Google Patents

Description

  The present invention relates to a temperature / thickness measuring apparatus, a temperature / thickness measuring method, a temperature / thickness measuring system, a control system, and a control method capable of accurately measuring the temperature or thickness of a measurement object such as a semiconductor wafer or a liquid crystal substrate. About.

  For example, accurate measurement of the temperature of a substrate to be processed, for example, a semiconductor wafer (hereinafter also simply referred to as “wafer”) processed by a substrate processing apparatus is performed on the wafer according to the results of various processes such as film formation and etching. This is extremely important from the viewpoint of accurately controlling the shape and physical properties of the film and holes to be formed. For this reason, the temperature of a wafer has been conventionally measured by various methods such as a resistance thermometer and a measurement method using a fluorescence thermometer for measuring the temperature of the back surface of a substrate.

  In recent years, a temperature measurement method and apparatus capable of directly measuring the wafer temperature, which has been difficult with the conventional temperature measurement method as described above, have been studied (see, for example, Patent Document 1). A specific example of such a temperature measuring apparatus will be described with reference to FIGS. 32 and 33. FIG. FIG. 32 is a diagram for explaining the principle of a conventional temperature measuring device, and FIG. 33 is a diagram conceptually showing an interference waveform measured by the temperature measuring device.

  The temperature measuring apparatus 10 shown in FIG. 32 uses a low coherence interferometer based on, for example, a Michelson interferometer. The temperature measuring apparatus 10 irradiates a light source 12 composed of, for example, a low-coherence SLD (Super Luminescent Diode), reference light that irradiates the reference mirror 20 with light from the light source 12 and a measurement target (for example, a wafer) 30. A beam splitter 14 that divides the measurement light into two, a reference mirror 20 that can be driven in one direction and can change the optical path length of the reference light, a reference light reflected from the reference mirror 20, and a reflection from the measurement object 30. And a light receiver 16 that receives the measurement light and measures the interference.

  In such a temperature measuring device 10, the light from the light source 12 is divided into the reference light and the measuring light by the beam splitter 14, and the measuring light is irradiated toward the measuring object 30 and both end faces of the measuring object. The reference light is reflected toward the reference mirror 20 and reflected from the surface of the reference mirror (for example, the front surface and the back surface). Then, the measurement light and the reference light reflected from each enter the beam splitter 14 again. At this time, depending on the optical path length of the reference light, the measurement light and the reference light are overlapped to cause interference, and the interference waveform is received by the light receiver. 16 is detected.

Therefore, when the temperature is measured, the reference mirror 20 is driven in one direction to change the optical path length of the reference light. Then, since the coherence length of the light from the light source 12 is short due to the low coherence property of the light source 12, normally, strong interference occurs in a place where the optical path length of the measurement light and the optical path length of the reference light coincide with each other, and in other places Interference is substantially reduced. Thus, the reference mirror 20 for example the front-rear direction is driven (arrow direction in FIG. 32), by changing the optical path length of the reference light, the refractive index difference in the measurement object 30 (e.g., measurement and air refractive index n _a The measurement light reflected from the front and back surfaces of the measurement object 30 interferes with the reference light reflected from the reference mirror due to the refractive index n) in the object 30, and an interference waveform as shown in FIG. 33A is detected. .

  The distance between peaks of these interference waveforms corresponds to the optical path length L between the surfaces constituting the thickness of the measurement object 30. This optical path length L can be expressed as L = d × n, where d is the thickness of the measuring object 30 and n is the refractive index. Since the thickness d and the refractive index n change according to the temperature change, the optical path length (optical thickness) L of the measuring object 30 also changes with the temperature change. For this reason, it is possible to measure the temperature in the depth direction of the measurement target by using the change in the optical path length L of the measurement target 30.

  For example, in FIG. 33, when the temperature of the measuring object 30 is changed by being warmed by a heater or the like, the measuring object 30 expands as shown by a one-dot chain line. At this time, since the refractive index n in the measurement object 30 also changes, as shown in FIGS. 33 (a) and 33 (b), the position of the interference waveform shifts before and after the temperature change, and the width between the peak positions of each interference waveform. The (peak-to-peak width) changes, and the change amount of the peak-to-peak width of the interference waveform corresponds to the change amount of the temperature change. Further, since the peak-to-peak width of the interference waveform corresponds to the movement distance of the reference mirror 20, the temperature change can be accurately measured by accurately measuring the peak-to-peak width of the interference waveform based on the movement distance of the reference mirror 20. Can be measured.

International Publication No. 03/087744 Pamphlet

  By the way, as described above, the optical path length (optical thickness) L of the measurement object 30 is expressed by thickness d × refractive index n, and the thickness d and the refractive index n change in a ratio with respect to temperature change. , The optical path length L also changes at a ratio to the temperature change. For this reason, as the thickness d of the measuring object 30 is thicker, the amount of change of the optical path length (optical thickness) L with respect to the temperature change becomes larger, and as the measuring object 30 is thinner, the optical path length (optical thickness) L is also increased. The amount of change with respect to temperature change is also reduced.

  For example, the change amount of the optical path length L in a silicon wafer having a thickness of 10 mm is 2.7 μm / ° C., whereas the change amount of the optical path length L in a wafer thinner than this, for example, a silicon wafer having a thickness of 0.75 mm, is It becomes considerably small at 0.2 μm / ° C.

  Thus, when the temperature of the measuring object 30 changes, the amount of change in the optical path length L of the measuring object 30 becomes smaller as the thickness d of the measuring object 30 is thinner (smaller). The amount of change in the peak-to-peak width of the interference waveform on the surface is also reduced. For this reason, the thinner the thickness d of the measuring object 30, the more difficult it is to accurately measure the amount of change in the peak-to-peak width of the interference waveform on each surface of the measuring object 30. Consequently, the temperature measurement accuracy of the measuring object is improved. There is a problem of hindering.

  Therefore, the present invention has been made in view of such problems, and the object of the present invention is to improve the measurement accuracy of the temperature or thickness of the measurement object regardless of the thickness of the measurement object. A temperature / thickness measuring device, a temperature / thickness measuring method, a temperature / thickness measuring system, a control system, and a control method are provided.

  In order to solve the above-described problem, according to one aspect of the present invention, light that is transmitted through and reflected from both end faces of a measurement object and that can be reflected back and forth at least twice at both end faces of the measurement object is irradiated. A light source, a splitter for splitting light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference reflecting from the reference light reflecting means Optical path length changing means for changing the optical path length of the light, reference light transmitting means for transmitting the reference light from the splitter to the reference light reflecting position for irradiating the reference light reflecting means, and measurement from the splitter Measurement light transmitting means for transmitting light to a measurement light irradiation position for irradiating the measurement object, measurement light that transmits or reflects the measurement object, and reference light that is reflected from the reference light reflection means are dried. A light receiving means for measuring the interference waveforms of the plurality of measurement lights obtained in this manner, and a reference interference waveform among the interference waveforms of the measurement light measured by the light receiving means. The measurement light between the two end surfaces of the measurement object is based on the reference interference waveform and the selected interference waveform, with the interference waveform of the measurement light that reciprocally reflects at least two times at both end surfaces of the measurement object as a selection interference waveform. There is provided a temperature / thickness measuring apparatus comprising a measuring means for measuring the optical path length of the measuring object and measuring the temperature or thickness of the measurement object based on the optical path length.

  In order to solve the above-described problem, according to another aspect of the present invention, the measurement light split from a light source that emits light that is transmitted through and reflected from both end faces of the measurement object is irradiated toward the measurement object. Irradiating the reference light toward the reference light reflecting means; and changing the optical path length of the reference light reflected from the reference light reflecting means by scanning the reference light reflecting means in one direction, A step of measuring an interference waveform of a plurality of measurement lights obtained by interference between the measurement light transmitted or reflected by the reference light reflected from the reference light reflecting means, and the interference waveform of the measurement light measured by the light receiving means The interference waveform of the measurement light that reciprocally reflects at least two end faces of the measurement object at least two times more than the measurement light of the reference interference waveform as a reference interference waveform is selected as the reference interference waveform. Measuring the optical path length of the measurement light between both end faces of the measurement object based on the waveform and the selected interference waveform, and measuring the temperature or thickness of the measurement object based on the optical path length. A featured temperature / thickness measurement method is provided.

  In such an apparatus or method according to the present invention, when the measurement light split from the light source is irradiated toward the measurement object, for example, the measurement light or the measurement light that directly passes through both end faces (for example, the front surface and the back surface) of the measurement object. It is possible to measure not only the interference waveform of the measurement light reflected at each end surface of the object, but also the interference waveform of the measurement light that is transmitted or reflected through the measurement object after being reciprocally reflected at both end surfaces of the measurement object at least once.

  Of these measured interference waveforms, for example, if the interference waveform of the measurement light reflected on the surface of the measurement object is the reference interference waveform, it is reflected on the back surface of the measurement object and reciprocates once on both end faces of the measurement object. Since the peak-to-peak width of the measured measurement light interference waveform and the reference interference waveform corresponds to the optical path length of the measurement light between both end faces of the measurement object, the interference of the measurement light reflected back and forth twice or more at both end faces of the measurement object The peak-to-peak width between the waveform and the reference interference waveform is at least twice the optical path length of the measurement light between both end faces of the measurement target.

  Therefore, by making the interference waveform of the measurement light reflected back and forth twice or more at both end faces of the measurement object as the selected interference waveform, the width between the peaks of the reference interference waveform and the selected interference waveform can be increased. The amount of change in the peak-to-peak width due to temperature change can be increased. Thereby, the measurement accuracy of the peak-to-peak width of each interference waveform can be improved.

  In particular, when the optical path length of the measurement light between both end faces of the measurement target is small (for example, when a thin semiconductor wafer or the like is the measurement target), the width of the reference interference waveform and the selected interference waveform is increased. As a result, the measurement accuracy of the peak-to-peak width of these interference waveforms can be greatly improved. Thereby, since the measurement accuracy of the optical path length of the measurement light between both end faces of the measurement object can be improved, the measurement accuracy of temperature or thickness can also be improved.

  In the above apparatus or method, the selected interference waveform is, for example, a reference approximate curve obtained by curve approximation of the entire wave train constituting the interference waveform (for example, the reference approximate curve of the whole wave stream constituting the interference waveform is a normal distribution curve) and , An approximate curve obtained by approximating the interferogram of the interference waveform based on the individual repetitive waveforms constituting the interferogram of the interference waveform (for example, an envelope obtained based on each repetitive waveform constituting the interlink of the interference waveform) Alternatively, the selection may be made based on the degree of collapse of the interference waveform indicated by the amount of deviation.

  As described above, the width between the reference interference waveform and the selected interference waveform can be increased as the interference waveform of the measurement light having a larger number of round-trip reflections between the both end faces of the measurement object is selected. Measurement accuracy can be further improved. However, on the other hand, the interference waveform of the measurement light with such a large number of round-trip reflections decreases the light intensity and increases the degree of collapse of the interference waveform. For example, when the degree of collapse of the interference waveform exceeds a predetermined value, the width between peaks of the interference waveform This is a factor that reduces the measurement accuracy. Therefore, if the selected interference waveform is selected based on the degree of collapse of the interference waveform, the reference interference waveform and the selected interference waveform can be selected within a range in which the degree of collapse of the interference waveform does not reduce the measurement accuracy of the peak-to-peak width of the interference waveform. It is possible to easily select an interference waveform that can be longer.

  Further, in the above apparatus or method, a detour optical path connected in parallel with the optical path of the measurement light is provided in the middle of the optical path of the measurement light, and the measurement light passing through these optical paths is irradiated to the measurement object, thereby performing measurement. The types (patterns) of light interference waveforms can be increased. For example, with respect to the interference waveform of measurement light that is reflected back and forth the same number of times on both end faces of the measurement object, it is possible to measure the interference waveform that passes through the optical path that does not pass through the bypass optical path and the optical path that passes through the bypass optical path at least once. it can. Deviations occur in these interference waveforms, and the deviation amount can be adjusted by adjusting the optical path length of the detour optical path of the measurement light.

  Therefore, by adjusting the optical path length of the bypass optical path of the measurement light, either the interference waveform of the measurement light passing through the optical path not passing through the bypass optical path or the interference waveform of the measurement light passing through the optical path passing through the bypass optical path at least once. The reference interference waveform selected from the interference waveform of the measurement light passing through one of the optical paths and the selected interference waveform selected from the interference waveform of the measurement light passing through the other optical path are respectively measured in the vicinity. Can do. For this reason, it is sufficient to move the reference light reflecting means (for example, the reference mirror) at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference light reflecting means (for example, the reference mirror) can be shortened, the time required for temperature or thickness measurement can also be shortened.

  Further, in the above apparatus or method, the reference light reflecting means is provided with a plurality of reflecting surfaces, and the reference light from the splitter is irradiated to the reference light reflecting means and reflected by the reflecting surfaces, so that a plurality of different optical path lengths are provided. By reflecting the reference light, the types (patterns) of interference waveforms between the reference light and the measurement light can be increased. For example, even with respect to the interference waveform of measurement light that is reflected back and forth the same number of times on both end faces of the measurement object, it is possible to measure the interference waveforms of a plurality of reference light and measurement light having different optical path lengths. Deviations occur in these interference waveforms, and the deviation amount can be adjusted by adjusting the positions of the plurality of reflecting surfaces of the reference light reflecting means.

  Therefore, by adjusting the positions of the plurality of reflecting surfaces of the reference light reflecting means, the interference waveform between the reference light reflected from one of the reflecting surfaces and the measurement light among the plurality of reference lights reflected from the respective reflecting surfaces. The reference interference waveform selected from the above, the selected interference waveform selected from the interference waveform of the reference light reflected from another reflecting surface and the measurement light can be respectively measured in the vicinity. For this reason, it is sufficient to move the reference light reflecting means (for example, the reference mirror) at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference light reflecting means (for example, the reference mirror) can be shortened, the time required for temperature or thickness measurement can also be shortened.

Further, in the above apparatus or method, a reference light splitter for further splitting the reference light from the splitter into a plurality of reference lights is provided, and the plurality of reference lights from the reference light splitter are different from each other with different optical path lengths. By irradiating and reflecting the reflection means,
The types (patterns) of interference waveforms of such reference light and measurement light can be increased. For example, with respect to the interference waveform of measurement light that is reflected back and forth the same number of times on both end faces of the measurement object, the interference waveforms of a plurality of reference beams and measurement beams having different optical path lengths can be measured. There is a shift in the interference of these lights, and the shift amount can be adjusted by adjusting the optical path lengths of the plurality of reference lights from the reference light splitter.

  Therefore, by adjusting the optical path lengths of the plurality of reference beams from the reference beam splitter, it is selected from the interference waveforms of one of the reference beams and the measurement beam among the plurality of reference beams split from the reference beam splitter The reference interference waveform and the selected interference waveform selected from the interference waveforms of another reference beam and measurement beam can be measured in the vicinity. For this reason, it is sufficient to move the reference light reflecting means (for example, the reference mirror) at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference light reflecting means (for example, the reference mirror) can be shortened, the time required for temperature or thickness measurement can also be shortened.

  In the above apparatus or method, a bypass optical path connected in parallel with the optical path of the reference light is provided in the middle of the optical path of the reference light, and the reference light passing through these optical paths is irradiated and reflected on the reference light reflecting means. By reflecting a plurality of reference lights having different optical path lengths, the types (patterns) of interference waveforms of measurement light can be increased. For example, the interference waveform of the measurement light that is reflected back and forth by the same number of times on both end faces of the measurement object also passes through the optical path that passes through the bypass optical path at least once with the reference light passing through the optical path that does not pass through the bypass optical path. The interference waveform between the reference light and the measurement light can be measured. Deviations occur in these interference waveforms, and the deviation amount can be adjusted by adjusting the optical path length of the detour optical path of the reference light.

  Therefore, by adjusting the optical path length of the detour optical path of the reference light, the interference waveform of the reference light passing through the optical path not passing through the detour optical path and the measurement light, and the reference light passing through the optical path passing through the bypass optical path and the measurement light at least once. Of the interference waveforms, the reference interference waveform selected from the interference waveform of the reference light and measurement light passing through one of the optical paths, and the selected interference waveform selected from the interference waveform of the reference light and measurement light passing through the other optical path Can be measured in the vicinity. For this reason, it is sufficient to move the reference light reflecting means (for example, the reference mirror) at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference light reflecting means (for example, the reference mirror) can be shortened, the time required for temperature or thickness measurement can also be shortened.

  In the above apparatus or method, each light (light from a light source, measurement light, reference light, etc.) may be transmitted via the air. According to this, light can be transmitted without using an optical fiber or a collimating fiber. Thereby, even light having a wavelength that does not pass through the optical fiber or collimate fiber (for example, a wavelength of 2.5 μm or more) can be used as a light source.

  In the above apparatus or method, the measurement object is formed of, for example, silicon or a silicon oxide film, and the light source is configured to be capable of irradiating light having a wavelength of, for example, 1.0 to 2.5 μm. Such light having a wavelength of 1.0 to 2.5 μm passes through and reflects the silicon or silicon oxide film constituting the measurement object, so that interference of measurement light that reciprocally reflects both ends of the measurement object twice or more. Waveform can be measured.

  In the above apparatus or method, the measurement object is, for example, a substrate to be processed (for example, a semiconductor wafer, a glass substrate, or the like) processed in a substrate processing apparatus (for example, a plasma processing apparatus) or the substrate to be processed. It is an electrode plate (for example, an electrode plate for an upper electrode, an electrode plate for a lower electrode, etc.). As described above, according to the present invention, it is possible to improve the measurement accuracy of the temperature or thickness of the thin measurement target as described above.

  Further, the measurement light transmission means in the apparatus is arranged on one side of the measurement object, transmits the measurement light from the light source, irradiates the measurement object on one end surface, and The measurement light that is reflected back and forth at both end surfaces or reflected at one end surface without reciprocation and returned can be received and transmitted to the light receiving means. Further, the measurement light transmission means in the apparatus is arranged on one side of the measurement object, transmits the measurement light from the light source, and irradiates the measurement light transmission means to one end surface of the measurement object; It is arranged on the other side of the measuring object, and reciprocally reflects at both end faces of the measuring object or transmits through one end face without reciprocating and receives measuring light transmitted through the other end face to receive the light. You may make it provide separately the light reception transmission means transmitted to a means.

  In the above method, the light intensity of the light source may be changed during measurement of light interference between the measurement light and the reference light. For example, the light intensity of the light source is gradually increased according to the moving distance of the reference light reflecting means, or the light intensity of the light source is increased as the interference waveform of the measurement light has a large number of reciprocal reflections on both end faces of the measurement target. Alternatively, the reflection intensity of the measurement light received by the light receiving means may be measured in advance, and the light intensity of the light source may be changed according to the reflection intensity. As a result, during measurement of the interference between the measurement light and the reference light, it is possible to prevent a decrease in the light intensity of the measurement light due to reciprocal reflection of the measurement light on the measurement object. It is possible to prevent the interference waveform from collapsing by preventing a decrease in light intensity (S / N ratio) with respect to noise of the waveform. Thereby, for example, the detection accuracy of the peak position of the interference waveform can be improved, and the measurement accuracy of temperature and thickness based on the peak-to-peak width of the interference waveform can be improved.

  In order to solve the above-described problems, according to another aspect of the present invention, a substrate processing apparatus that performs a predetermined process on a substrate to be processed in a processing chamber, a temperature / thickness measuring apparatus attached to the substrate processing apparatus, A temperature / thickness measurement system including a control device for controlling the temperature / thickness measurement device, wherein the temperature / thickness measurement device transmits and reflects both end faces of the substrate to be measured. A light source that emits light that can be reflected back and forth at least twice at both end faces of the substrate to be processed, a splitter for splitting light from the light source into measurement light and reference light, and the splitter Reference light reflecting means for reflecting the reference light from the reference light, optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means, and reference light from the splitter reflecting the reference light Towards the means A reference light transmission means for transmitting to a reference light irradiation position for irradiation, a measurement light transmission means for transmitting measurement light from the splitter to a measurement light irradiation position for irradiating the processing substrate, and the substrate to be processed. And a light receiving means for measuring interference waveforms of a plurality of measurement lights obtained by interference between the measurement light transmitted or reflected and the reference light reflected from the reference light reflection means. Of the interference waveform of the measurement light measured by the light receiving means of the thickness measuring device, a certain interference waveform is used as a reference, and both end faces of the substrate to be processed are reflected at least twice more than the measurement light of this reference interference waveform. And measuring the optical path length of the measurement light between both end faces of the substrate to be processed based on the reference interference waveform and the selected interference waveform, and using the interference waveform of the measurement light as a selective interference waveform. Serial temperature / thickness measurement system and measuring the temperature or the thickness of the substrate is provided.

  According to such a temperature / thickness measurement system according to the present invention, the reference interference waveform and the selection can be made even for a measurement target such as a substrate to be processed or an electrode plate whose thickness is thin and the optical path length of the measurement light between both end faces is short. Since the width of the interference waveform can be increased, the measurement accuracy of the peak-to-peak width of these interference waveforms can be greatly improved. Thereby, since the measurement accuracy of the optical path length of the measurement light between both end faces of the measurement object can be improved, the measurement accuracy of temperature or thickness can also be improved.

  In order to solve the above-described problems, according to another aspect of the present invention, a substrate processing apparatus that performs a predetermined process on a substrate to be processed in a processing chamber, and a temperature / thickness measuring apparatus installed in the substrate processing apparatus. And a control device for controlling the temperature / thickness measuring device and the substrate processing apparatus, and for controlling at least one of temperature control and process control of the substrate to be processed. / Thickness measuring device includes a light source that irradiates light that is transmitted through and reflected by both end surfaces of the substrate to be measured and that can be reflected back and forth at least twice at both end surfaces of the substrate to be processed; , A splitter for splitting light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference reflecting from the reference light reflecting means An optical path length changing means for changing the optical path length of the light source, a reference light transmitting means for transmitting the reference light from the splitter to the reference light irradiating position for irradiating the reference light to the reference light reflecting means, and a measuring light from the splitter Measurement light transmitting means for transmitting the measurement light to the processing substrate, the measurement light transmitting or reflecting the processing substrate and the reference light reflected from the reference light reflecting means interfere with each other. A light receiving means for measuring the interference waveforms of the plurality of measurement lights obtained, and the control device includes a certain interference waveform among the interference waveforms of the measurement light measured by the light receiving means of the temperature / thickness measurement device. The reference interference waveform and the selection are selected as an interference waveform of the measurement light that reciprocally reflects at least two times at both end faces of the substrate to be processed from the measurement light of the reference interference waveform. Based on the interference waveform, the optical path length of the measurement light between both end faces of the substrate to be processed is measured, and based on the optical path length, the temperature or thickness of the substrate to be processed is measured. A control system is provided that performs at least one of temperature control and process control of the substrate to be processed in a processing chamber of the substrate processing apparatus.

  According to such a control system according to the present invention, the reference interference waveform and the selected interference waveform can be measured even on a measurement target such as a substrate to be processed or an electrode plate whose thickness is small and the optical path length of the measurement light between both end faces is short. Since the width can be increased, the measurement accuracy of the peak-to-peak width of these interference waveforms can be greatly improved. As a result, the measurement accuracy of the optical path length of the measurement light between the both end faces of the measurement object can be improved, and thus the measurement accuracy of the temperature or thickness can be improved. Since the temperature control and process control of the processing substrate can be performed, the process characteristics of the substrate to be processed can be accurately controlled, and the stability of the substrate processing apparatus can be improved.

  In order to solve the above-described problems, according to another aspect of the present invention, there is provided a control method for a control system of a substrate processing apparatus that performs a predetermined process on a substrate to be processed in a processing chamber. Irradiating the measuring object with the split measurement light from the light source that irradiates the reflected and reflected light, and irradiating the reference light toward the reference light reflecting means, and the reference light reflecting means in one direction The measurement light transmitted or reflected by the measurement object and the reference light reflected from the reference light reflecting means interfere with each other while changing the optical path length of the reference light reflected from the reference light reflecting means by scanning to the reference light reflecting means. Measuring the interference waveform of the plurality of measurement lights, and using the interference waveform as a reference among the interference waveforms of the measurement light measured by the light receiving means, An optical path length of the measurement light between the both end faces of the measurement target based on the reference interference waveform and the selected interference waveform, with an interference waveform of the measurement light that reciprocally reflects at least two times at both end faces of the target as a selection interference waveform Measuring the temperature or thickness of the measurement target based on the optical path length, and the temperature of the substrate to be processed in the substrate processing apparatus based on the measured temperature or thickness of the measurement target. There is provided a control method comprising a step of performing at least one of control and process control.

  According to such a control method of the present invention, the reference interference waveform and the selected interference waveform can be measured even on a measurement target such as a substrate to be processed or an electrode plate having a small thickness and a short optical path length of the measurement light between both end faces. Since the width can be increased, the measurement accuracy of the peak-to-peak width of these interference waveforms can be greatly improved. As a result, the measurement accuracy of the optical path length of the measurement light between the both end faces of the measurement object can be improved, and thus the measurement accuracy of the temperature or thickness can be improved. Since the temperature control and process control of the processing substrate can be performed, the process characteristics of the substrate to be processed can be accurately controlled, and the stability of the substrate processing apparatus can be improved.

  As described above, according to the present invention, the width of the reference interference waveform and the selected interference waveform can be increased even in a measurement target having a small thickness and a short optical path length of the measurement light between both end faces. The measurement accuracy of the peak-to-peak width of the interference waveform can be greatly improved. Thereby, since the measurement accuracy of the optical path length of the measurement light between both end faces of the measurement object can be improved, the measurement accuracy of temperature or thickness can also be improved.

  The measurement target includes a measurement target layer that constitutes a part of the object, such as an inner layer of the substrate to be processed, in addition to the measurement target as an object such as the substrate to be processed.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Temperature measuring device according to the first embodiment)
A temperature measuring apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a temperature measuring apparatus according to the first embodiment of the present invention. The temperature measuring apparatus 100 according to the present embodiment is based on the principle shown in FIG. 32 described above, and has a simple configuration and a thickness such as a semiconductor wafer (hereinafter also simply referred to as “wafer”). The measurement accuracy of the thin measuring object T can be improved. A specific configuration of such a temperature measuring apparatus 100 is as follows.

  As shown in FIG. 1, the temperature measuring device 100 includes a light source 110, a splitter 120 for splitting light from the light source 110 into measurement light and reference light, and reference light from the splitter 120. The reference light reflecting means 140 for reflecting the light and the optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means 140 are provided. The optical path length changing means is constituted by a driving means 142 such as a motor for driving the reference light reflecting means 140 constituted by a reference mirror or the like in one direction parallel to the incident direction of the reference light. Thus, by driving the reference mirror in one direction, the optical path length of the reference light reflected from the reference mirror can be changed.

Further, the temperature measuring apparatus 100 reflects measurement light (for example, both ends of the measurement target T) reflected from the measurement target T when the measurement light from the splitter 120 is irradiated on _one end surface S1 of the measurement target T. The measurement light that is reflected back and forth by the surfaces S ₁ and S ₂ or reflected by the end surface S ₁ on one side without reciprocating) and the reference light reflecting means 140 is irradiated with the reference light from the splitter 120. And a light receiving means 150 for measuring a plurality of interference waveforms with the reference light reflected from the reference light reflecting means 140 (the plurality of interference waveforms are collectively referred to as light interference, for example).

(Types of measuring light by the temperature measuring device according to the first embodiment)
Here, in the temperature measurement apparatus as shown in FIG. 1, the main types of measurement light reflected from the measurement target T when the measurement light from the light source 110 is irradiated toward the measurement target T are referred to the drawings. While explaining. FIG. 2 is a conceptual diagram for explaining the types of measurement light, and the arrows shown in FIG. 2 indicate the measurement light reflected from the measurement object T. FIG. In FIG. 2, the reflection position of the measurement light is shifted so that the number of round-trip reflections between the both end faces of the measurement target T in the measurement light is easy to understand. The reflection angle also changes according to the irradiation angle. For example, if the measurement light is irradiated so as to be almost perpendicular to the measurement target T, the reflection positions at the end faces S ₁ and S ₂ also substantially overlap the optical axis of the measurement light.

As the measurement light reflected from the measurement object T, as shown in FIG. 2 (a), the measurement object T is never reciprocally reflected within the measurement object T, and one end surface (measurement light is irradiated). first surface) S ₁ in one reflected and returning measurement light (first surface once reflected measuring light or 0 strokes reflection measurement light) and as shown in FIG. 2 (b) is an end of that side the first surface S ₁ passes through the other side end surface of the measuring light (the first surface S ₁ the second surface S ₂ is the surface on the opposite _side) is reflected once by the measurement target T, i.e. the measurement object There is measurement light (second surface one-time reflection measurement light or one-time round-trip reflection measurement light) that reciprocally reflects once at both end faces S ₁ and S ₂ of T.

Further, in the present invention, in addition to the above-described measurement light, for example, as shown in FIG. 2C, the first surface S ₁ is transmitted through the first surface S ₁ of the measurement object T and reflected by the second surface S ₂ , and then the first surface S. ₁ and reflected again on the second surface S ₂ , that is, measurement light that is reflected twice back and forth on both end surfaces S ₁ and S ₂ of the measurement object T (second surface twice reflected measurement light or twice). reciprocally reflected measurement light) passes through a first surface S ₁ of the measurement target T as shown in FIG. 2 (d), the second side S ₂ three times, the measurement of reflected twice by the first surface S ₁ Light, that is, measurement light that is reflected back and forth three times at both end faces S ₁ and S ₂ of the measurement target T (second surface three-time reflection measurement light or three-time round-trip reflection measurement light), etc. There is also measurement light (second surface multiple reflection measurement light or multiple round-trip reflection measurement light) that is reciprocally reflected at both end faces S ₁ and S ₂ a plurality of times. Accordingly, the light receiving means 150 measures the interference waveforms between the measurement light and the reference light.

  Conventionally, the optical path length L of the measurement light in the measurement object T is measured using the zero round-trip reflection measurement light as shown in FIG. 2A and the single round-trip reflection measurement light as shown in FIG. However, in the present invention, in order to improve the temperature measurement accuracy of the thin measuring object T, the single round-trip reflected measurement light as shown in FIG. Instead of the above, temperature measurement is performed using a plurality of round trip reflection measurement lights as shown in FIGS. 2 (c) and 2 (d). A specific example of the interference waveform between the measurement light and the reference light as described above will be described later.

The light source 110 constituting such a temperature measuring device 100 is light that is transmitted and reflected at both end faces S ₁ and S ₂ of the measurement target T, and can be reflected back and forth at least twice at both end faces of the measurement target. In this case, light that can be irradiated with light that can measure interference between the measurement light split from the light source 110 and the reference light is used. This is because, in the present invention, the interference waveform between the measurement light and the reference light reflected back and forth at least twice at both end faces S ₁ and S ₂ of the measurement target T is used for measuring the temperature of the measurement target T.

For example, when measuring the temperature of a wafer as the measurement target T, the light source 110 has light that does not interfere with reflected light from at least the distance between the both end faces of the wafer (usually about 800 to 1500 μm). preferable. Specifically, for example, it is preferable to use low coherence light. Low coherence light refers to light with a short coherence length. The center wavelength of the low coherence light is preferably 0.3 to 20 μm, for example, and more preferably 0.5 to 5 μm. The coherence length is preferably 0.1 to 100 μm, for example, and more preferably 3 μm or less. By using such low-coherence light as the light source 110, it is possible to avoid an obstacle due to unnecessary interference, and the measurement light reflected from both end faces S ₁ and S _{2 of the} wafer and other layers having different refractive indexes are provided inside the wafer. In this case, the interference waveform between the measurement light reflected from the boundary surface and the reference light can be easily measured.

  Examples of the light source using the low-coherence light include SLD (Super Luminescent Diode), LED, high-intensity lamp (tungsten lamp, xenon lamp, etc.), ultra-wideband wavelength light source, and the like. Among these low-coherence light sources, it is preferable to use an SLD as the light source 110 in view of high brightness.

  As the splitter 120, for example, an optical fiber coupler is used. However, the present invention is not limited to this, and any material that can be split into reference light and measurement light may be used. As the splitter 120, for example, an optical waveguide type demultiplexer, a half mirror, or the like may be used.

  The reference light reflecting means 140 is constituted by a reference mirror, for example. As the reference mirror, for example, a corner cube prism, a plane mirror, or the like is applicable. Among these, it is preferable to use a corner cube prism in view of parallelism with incident light of reflected light. However, as long as the reference light can be reflected, the present invention is not limited to the above, and may be constituted by, for example, a delay line (similar to an optical path changing means such as a piezo tube delay line described later).

  The driving means 142 for driving the reference light reflecting means 140 is preferably constituted by, for example, a stepping motor that is driven in a direction parallel to the incident direction of the reference light (arrow direction in FIG. 1). If the stepping motor is used, the moving distance of the reference light reflecting means 140 can be easily detected by the motor driving pulse. However, the optical path length changing means is not limited to the motor as long as the optical path length of the light reflected from the reference light reflecting means can be changed. For example, a voice coil motor type delay line using a voice coil motor is used. In addition, the optical path length changing means may be constituted by a piezo tube type delay line, a linear motion stage type delay line, a laminated piezo type delay line, or the like.

  The light receiving means 150 is preferably configured using, for example, a photodiode in consideration of low cost and compactness. Specifically, for example, a PD (Photo Detector) using a Si photodiode, an InGaAs photodiode, a Ge photodiode, or the like is used. However, as long as the interference of the measurement light from the measurement object T and the reference light from the reference light reflecting means 140 can be measured, the light is not limited to the above, and is received using, for example, an avalanche photodiode or a photomultiplier tube. The means 150 may be configured.

The reference light from the splitter 120 is transmitted to a reference light irradiating position for irradiating the reference light reflecting means 140 via a reference light transmitting means (for example, an optical fiber F _Z with a collimator having a collimator attached to the tip of the optical fiber c). It has become so. Further, the measurement light from the splitter 120 is transmitted to the measurement light irradiating position for irradiating the measurement target T via the measurement light transmission means (for example, the optical fiber F with a collimator having a collimator attached to the tip of the optical fiber b). It has come to be. That is, the measuring light transmission means in the temperature measuring apparatus 100 as shown in FIG. 1 is arranged on one side of the measuring object T, transmits the measuring light from the light source 110, and has one end face ( first surface) toward _{S 1} is irradiated. Further, such a measuring light transmission means reflects back and forth at both end faces S ₁ and S ₂ of the measuring object T or reflects off one end face (first face) S ₁ without going back and forth and returns. The incoming measurement light is received and transmitted to the light receiving means 150. The reference light transmission means or the measurement light transmission means is not limited to the collimator-equipped optical fiber, and may be a collimated fiber.

  The intensity ratio between the measurement light split by the splitter 120 and the reference light is, for example, 1: 1. As a result, the intensity of the measurement light and the reference light become substantially the same, so that an interference waveform that makes it easy to measure the width between peaks, for example, can be obtained. The intensity of each light is not limited to this.

(Operation of the temperature measuring apparatus according to the first embodiment)
In the temperature measuring apparatus 100 having such a configuration, as shown in FIG. 1, the light from the light source 110 is incident on one of the input terminals (input ports) of the splitter 120 via the optical fiber a, for example. Is divided into two output terminals (output ports). Among these, the light from one output terminal (output port) is used as measurement light to one side of the measurement object T via measurement light transmission means, for example, an optical fiber F with a collimator having a collimator attached to the tip of the optical fiber b. Irradiated. In this embodiment, when the measurement light is irradiated onto the measurement target T in this way, the measurement light reflected from the measurement target T and returns to the same side as shown in FIG. To do.

On the other hand, the light from the other output terminal of the splitter 120 is 2 minutes wave (output port) as the reference light, emitted from the reference light transmitting means such as an optical fiber c distal to the collimator optical fiber with F _Z, fitted with a collimator , And reflected by a reference light reflecting means (for example, a reference mirror) 140. Then, the measurement light reflected from the measurement target object T is incident on the splitter 120 via the optical fiber F with collimators, the reference beam reflecting means (e.g., a reference mirror) beam with the reference beam reflected even collimator 140 fiber F _Z The measurement light and the reference light are recombined via the splitter 120, and the light is combined with the light receiving means 150, which is constituted by a PD using, for example, a Si photodiode, an InGaAs photodiode, a Ge photodiode, or the like. Then, the light receiving unit 150 detects an interference waveform between the measurement light and the reference light.

(Specific example of interference waveform between measurement light and reference light)
Here, a specific example of the light interference between the measurement light and the reference light obtained by the temperature measurement apparatus 100 is shown in FIG. FIG. 3 shows an interference waveform between each measurement light as shown in FIG. 2 reflected from the measurement object T and the reference light reflected by the reference light reflecting means 140. 3A shows the interference waveform before the temperature change, and FIG. 3B shows the interference waveform after the temperature change. In FIG. 3, the vertical axis represents the interference intensity, and the vertical axis represents the moving distance of the reference mirror.

  Further, as the light source 110, a low coherence light source capable of transmitting and reflecting the measurement target T is used. According to the low-coherence light source, since the coherence length of the light from the light source 110 is short, usually strong interference occurs in a place where the optical path length of the measurement light and the optical path length of the reference light coincide with each other, and interference occurs in other places. It has the characteristic of being substantially reduced. For this reason, the reference light reflecting means (for example, the reference mirror) 140 is driven back and forth in the reference light irradiation direction, for example, and the optical path length of the reference light is changed, as shown in FIGS. Each measurement light and reference light interfere.

  According to FIGS. 3A and 3B, when the reference light reflecting means (for example, the reference mirror) 140 is scanned in one direction, the first-surface first-time reflection measurement as shown in FIG. An interference waveform between the light (0 roundtrip reflection measurement light) and the reference light appears, and then the second surface single reflection measurement light (1 roundtrip reflection measurement light) and the reference light as shown in FIG. An interference waveform appears. When the reference light reflecting means 140 is further scanned, an interference waveform between the second surface twice reflected measurement light (twice round trip reflected measurement light) and the reference light appears as shown in FIG. An interference waveform between the second-surface three-time reflected measurement light (three-time reciprocal reflection measurement light) and the reference light as shown in FIG. Thereafter, if the reference light reflecting means 140 is further scanned, although not shown, the second surface 4 times reflection measurement light (4 times reciprocation reflection measurement light), the second surface 5 times reflection measurement light (5 times reciprocation reflection measurement light). Thus, the interference waveform of each measurement light appears continuously at equal intervals.

(Temperature measurement method based on interference wave)
Next, a method for measuring temperature based on the interference of light between measurement light and reference light will be described. As a temperature measurement method based on the interference wave of the measurement light and the reference light, for example, there is a temperature conversion method using an optical path length change based on a temperature change. Here, a temperature conversion method using a position shift of an interference waveform based on a temperature change will be described.

When the measuring object T is warmed by a heater or the like, the measuring object T expands and the thickness d and the refractive index n change. Therefore, both end faces S of the measuring object T before and after the temperature change. _1, since between S ₂ is the optical path length (optical thickness) L of (between the surface and the back surface) varies, the position is shifted in the interference waveform of the measurement light and the reference light, the peak-to-peak width of the interference waveform changes To do. Therefore, a temperature change can be detected by measuring the peak-to-peak width of the interference waveform of the measurement target T. For example, the optical path length L of the measurement target T corresponds to, for example, the peak-to-peak width between the interference waveform of the first-surface once-reflected measurement light and the interference waveform of the second-surface once-reflected measurement light shown in FIG. Since the peak-to-peak width corresponds to the moving distance of the reference light reflecting means (for example, the reference mirror) 140, by measuring the moving distance of the reference mirror in the peak-to-peak width of these interference waveforms, before and after the temperature change The optical path length L of the measurement object T can be measured.

  Hereinafter, the temperature measurement method will be described more specifically with the thickness of the measurement target T measured in FIG. 3 as d and the refractive index as n. When the measurement object T is irradiated with measurement light and the reference mirror is scanned in one direction, as shown in FIG. 3A, the first surface once reflected measurement light interference waveform, the second surface once The interference waveform of the reflected measurement light, the interference waveform of the second surface twice reflected measurement light, and the interference waveform of the third surface three times reflected measurement light are obtained in this order.

  At this time, when the measuring object T is heated by, for example, a heater, the temperature of the measuring object T rises, and the measuring object T expands due to the temperature change, and the refractive index n also changes. As a result, the peak positions of other interference waveforms are shifted with reference to one interference waveform of the measurement target T, and the peak-to-peak width of the interference waveform changes. For example, in FIG. 3B, the interference waveform of the first-surface once reflected measurement light of the measurement object T is used as a reference interference waveform, and the position of the other interference waveform, that is, the second surface once reflected, the second surface twice. The position of the interference waveform of the reflected and third surface three-time reflected measurement light is shifted by t, 2t, and 3t, respectively, as compared with the case of FIG. As a result, the peak-to-peak widths of the reference interference waveform and the other interference waveforms change from W, 2W, 3W shown in FIG. 3A to W ′, 2W ′, 3W ′ shown in FIG. 3B, respectively.

  Such a shift in the peak position of the interference waveform generally depends on the linear expansion coefficient α specific to each layer of the measurement object with respect to the thickness d, and mainly changes in the refractive index specific to each layer with respect to changes in the refractive index n. Depends on temperature coefficient β. It is known that the temperature coefficient β of the refractive index change also depends on the wavelength.

  Therefore, when the thickness d ′ after the temperature change in the measuring object T is expressed by a mathematical expression, the following mathematical expression (1-1) is obtained. In the following mathematical formula (1-1), ΔT represents a temperature change of the measuring object T. α indicates the linear expansion coefficient of the measuring object T, and β indicates the temperature coefficient of the refractive index change of the measuring object T. D and n indicate the thickness and refractive index of the measuring object T before the temperature change.

d ′ = d · (1 + αΔT), n ′ = n · (1 + βΔT) (1-1)

As shown in the above equation (1-1), the optical path length of the measurement light that is transmitted through and reflected by the measurement target T is changed due to the temperature change. The optical path length is generally expressed as a product of the thickness d and the refractive index n. Accordingly, if the optical path length of the measurement light transmitted through and reflected by the measurement target T before the temperature change is L, and the optical path length after the temperature at the measurement target T is changed by ΔT is L ′, then L ₁ , L ₁ 'is as shown in the following formula (1-2).

L = d · n, L ′ = d ′ · n ′ (1-2)

  Accordingly, the difference (L′−L) between the optical path length of the measurement light at the measurement object T and before and after the temperature change is calculated and arranged according to the above formulas (1-1) and (1-2). -3). In addition, in the following mathematical formula (1-3), a minute term is omitted in consideration of α · β << α and α · β << β.

L′−L = d ′ · n′−d · n = d · n · (α + β) · ΔT
= L · (α + β) · ΔT (1-3)

  Here, the optical path length L of the measurement light at the measurement object T corresponds to the width between peaks of the interference waveform between the measurement light and the reference light. For example, the optical path length L of the measurement light of the measurement target T before the temperature change corresponds to the peak-to-peak width W of the interference waveform shown in FIG. 3A, and the optical path length of the measurement light of the measurement target T after the temperature change. L ′ corresponds to the peak-to-peak width W ′ of the interference waveform shown in FIG. Therefore, the peak-to-peak width of the interference waveform with the reference light in the measurement target T can be measured by the moving distance of the reference light reflecting means (for example, the reference mirror) 140 according to the temperature measuring apparatus 100 as shown in FIG.

  Therefore, if the linear expansion coefficient α and the temperature coefficient β of the refractive index change of the measurement target T are examined in advance, the above formula ( 1-3) can be used to convert the temperature of the measuring object T.

  Thus, when converting the interference wave to the temperature, the optical path length expressed between the peaks of the interference waveform varies depending on the linear expansion coefficient α and the temperature coefficient β of the refractive index change as described above. It is necessary to investigate in advance α and the temperature coefficient β of the refractive index change. In general, the linear expansion coefficient α and the temperature coefficient β of refractive index change of a substance including a wafer that can be the measurement object T may depend on the temperature depending on the temperature range. For example, the coefficient of linear expansion α generally does not change so much in the temperature range of about 0 to 100 ° C., so it can be regarded as constant. However, in the temperature range of 100 ° C. or higher, the temperature increases depending on the material. Since the rate of change may be large, the temperature dependency cannot be ignored in such a case. Similarly, the temperature dependence β of the refractive index change may not be negligible depending on the temperature range.

For example, in the case of silicon (Si) constituting a wafer, it is known that the linear expansion coefficient α and the temperature coefficient β of refractive index change can be approximated by, for example, a quadratic curve in a temperature range of 0 to 500 ° C. For details, see JAMcCaulley, VMDonnelly et al. (JAMcCaulley, VMDonnelly, M. Vernon, and I. Taha,
"Temperature dependence of the near-infrared refractive index of
silicon, gallium arsenide, and indium phosphide "Phy. Rev. B49, 7408, 1994).

  Thus, since the linear expansion coefficient α and the temperature coefficient β of the refractive index change depend on the temperature, for example, the linear expansion coefficient α and the temperature coefficient β of the refractive index change corresponding to the temperature are examined in advance through experiments, etc. If it is stored in advance in a memory (for example, a memory 440 of the control device 400 described later) as the reference data for use, and the temperature is converted using the reference data for temperature conversion, it can be converted into a more accurate temperature.

  Note that the method for measuring the temperature based on the interference wave between the measurement light and the reference light is not limited to the above method, and the relationship between the optical path length and the temperature for the measurement target T is obtained in advance through experiments, The temperature conversion reference data is stored in advance in a memory (for example, a memory 440 of the control device 400 described later), and the temperature conversion reference data is used to calculate the measurement light and the reference light for the measurement target T. The optical path length (inter-peak width of the interference waveform) measured based on the interference wave may be directly converted into temperature. According to this, even if the linear expansion coefficient α and the temperature coefficient β of the refractive index change are not known, the measurement result of the interference wave between the measurement light and the reference light can be easily converted into temperature.

For the measurement target object T in particular in example, the optical path length at a known temperature t _i and L _i, the optical path length at a given temperature t and L _t, a temperature coefficient of linear expansion α and the refractive index change β Then, in a temperature range in which the temperature dependence of the linear expansion coefficient α and the temperature coefficient β of the refractive index change can be ignored, a certain temperature t can be expressed by the following equation (2-1). The following equation (2-1) is the same as the case where L ′ = L _t , L = L _i , and ΔT = t−t _i in the above equation (1-3). When the following (2-1) is arranged, a certain temperature t can be expressed by the following equation (2-2). In the following equation (2-2), when the temperature dependence of the linear expansion coefficient α and the temperature coefficient β of the refractive index change can be ignored, α + β is considered to be constant, so the constant coefficients are replaced with A ₁ and B ₁ . And a linear expression as shown in the following expression (2-3).

L _t −L _i = L _i · (α + β) · (t−t _i ) (2-1)

t = (1 / (α + β)) · (L _t / L _i ) − (1 / (α + β) + t _i ) (2-2)

t = A ₁ · (L _t / L _i ) + B ₁ (2-3)

When the temperature dependence of the linear expansion coefficient α and the temperature coefficient β of the refractive index change cannot be ignored, it may be expressed by a quadratic expression as shown in the following expression (2-4). The coefficients in this case are A ₂ , B ₂ and C ₂ .

t = A ₂ · (L _t / L _i ) ² + B ₂ · (L _t / L _i ) + C ₂ (2-4)

The coefficients A ₁ , B _{1 in} the above equation (2-3) and the coefficients A ₂ , B ₂ , C ₂ in the above equation (2-4) are actually measured at several temperatures by experiments. Ask for. For example, if an experimental result as shown in FIG. 4 is obtained with respect to the relationship between the temperature and the optical path length, the known temperature t _{i is set} to 40 ° C., and the optical path length at that time is set to L _i = L _40. −4) The coefficients in the equation are A ₂ = −1.2496 × 10 ⁵ , B ₂ = −2.6302 × 10 ⁵ , and C ₂ = −1.3802 × 10 ⁵ , respectively.

The equation (2-4) thus obtained by experiment is stored in advance in a memory (for example, a memory 440 of the control device 400 to be described later) as temperature conversion reference data, and based on the interference wave between the measurement light and the reference light. from the measured optical path length _{L t} seek _L t _{/ L 40} Te, by fitting the _L t / _{L i} of (2-4) below, it is possible to convert the optical path length _{L t} of the temperature t.

  Note that the temperature measurement method based on the interference wave between the measurement light and the reference light is not limited to the method described above. For example, a method using an absorption intensity change based on a temperature change may be used. A method in which an optical path length change based on the above and an absorption intensity change based on a temperature change are combined may be used.

As described above, the optical path length L ′ of the measurement light in the measurement target T after the temperature change is, for example, the interference waveform of the measurement light reflected by both end faces S ₁ and S ₂ of the measurement target T (FIG. 3B). This corresponds to the peak-to-peak width W ′ of the first-surface once-reflected measurement light interference waveform and second-surface one-time reflected measurement light interference waveform shown in FIG. By converting the obtained optical path length L ′ into temperature, the temperature of the measuring object T can be measured.

  However, the amount of change (L′−L) per unit temperature change (for example, 1 ° C.) of the optical path length L of the measuring light in the measuring object T as shown in FIG. 3 depends on the above equation (1-3). For example, the smaller the thickness d of the measuring object T is, the smaller it becomes. Therefore, between the interference waveform of the first surface once reflected measurement light and the second surface once reflected measurement light corresponding to the optical path length L. The change amount t of the width W is also reduced. For this reason, the smaller the thickness d of the measuring object T, the more difficult it is to accurately measure the amount of change t between the peak-to-peak widths W of the interference waveform of the measuring object T, and consequently the temperature of the measuring object T. There is a problem that the measurement accuracy is hindered.

Therefore, in order to take longer peak width of the interference waveform, end surfaces S ₁ of the measurement target T as the second surface double reflection or interference waveform of the second surface 3 times reflected measuring _beam, S ₂ The interference waveform of the measurement light reflected back and forth twice or more (interference waveform of the measurement light reflected back and forth multiple times) is used for temperature measurement.

For example, the second surface twice reflected measurement light is reflected twice on both end faces S ₁ and S ₂ of the measurement object T as shown in FIG. The inter-peak width 2W of the interference waveform of the measurement light and the interference waveform of the first-surface once reflected measurement light is twice the optical path length L of the measurement light in the measurement target T as shown in FIG. It corresponds to 2L. Accordingly, the inter-peak widths 2W and 2W ′ of the interference waveform before and after the temperature change are measured, and the measurement light in this case is measured by 2 which is the number of round-trip reflections at both end faces S ₁ and S ₂ of the measurement target T. By dividing the peak-to-peak widths 2W and 2W ′, the optical path lengths L and L ′ of the measurement light of the measurement object T can be obtained. For this reason, the amount of change in the peak-to-peak width (2W′−2W) when using the interference waveform of the second surface twice reflected measurement light is the same as when the interference waveform of the second surface once reflected measurement light is used. Since it becomes twice 2t, the measurement accuracy can be improved.

Further, since the second surface three-time reflected measurement light is reflected back and forth three times at both end faces S ₁ and S ₂ of the measuring object T as shown in FIG. The peak-to-peak width 3W of the interference waveform of the reflected measurement light and the interference waveform of the first-surface once reflected measurement light is three times the optical path length L of the measurement light of the measurement object T as shown in FIG. It corresponds to 3L. Accordingly, the inter-peak widths 3W and 3W ′ of the interference waveform before and after the temperature change are measured, and the measurement light is measured with 3 which is the number of round-trip reflections at both end faces S ₁ and S ₂ of the measuring object T in this case. By dividing the peak-to-peak widths 3W and 3W ′, the optical path lengths L and L ′ of the measuring light in the measuring object T can be obtained. For this reason, the amount of change in the peak-to-peak width (3W'-3W) when the interference waveform of the second-surface three-time reflected measurement light is used is the same as when the interference waveform of the second-surface one-time reflected measurement light is used. Since 3 to 3 times, the measurement accuracy can be further improved as compared with the case of using the interference waveform of the second surface twice reflected measurement light.

Thus, for example the interference waveform of the measurement light the first surface S ₁ reflects a single measurement target T as a reference, the second side S ₂ of the measuring light interference waveform which reflects a single measurement object T Instead, if an interference waveform of measurement light that is reflected twice or more at both end faces S ₁ and S ₂ of the measurement target T is selected, the width between peaks of the reference interference waveform and the selected interference waveform is measured. Since the peak-to-peak width of each interference waveform to be measured can be increased, the amount of change is also increased, so that the measurement accuracy of the peak-to-peak width of each interference waveform can be improved. Moreover, since the peak-to-peak width of each interference waveform to be measured can be increased as the number of reflections on the surfaces S ₁ and S ₂ of the measurement target T increases, the measurement accuracy of the peak-to-peak width of each interference waveform is also improved. Can be made. As a result, the temperature measurement accuracy of the measuring object T can be improved.

(Temperature measurement system according to the second embodiment)
Next, a temperature measurement system for a substrate processing apparatus according to a second embodiment will be described with reference to the drawings. The temperature measurement system of the substrate processing apparatus according to the second embodiment is a specific example when the temperature measurement apparatus according to the first embodiment is applied to the substrate processing apparatus. FIG. 5 is a diagram showing a schematic configuration of a temperature measurement system according to the second embodiment. Here, as an example of the temperature measurement target T in a substrate processing apparatus such as a plasma etching apparatus, a case where it is applied to the temperature measurement of the wafer Tw will be described as an example.

  The temperature measurement system shown in FIG. 5 is roughly composed of a temperature measurement device 200, a substrate processing device 300, and a control device 400. A temperature measuring apparatus 200 shown in FIG. 5 includes a light source 110 shown in FIG. 1 as a low-coherence light source, for example, an SLD 210 that emits light having low coherence, and a splitter that splits the light from the light source 110 into measurement light and reference light. 120 includes, for example, a 2 × 2 optical fiber coupler 220, and the light receiving unit 150 includes, for example, a PD 250 using a Ge photodiode, the reference light reflecting unit 140 includes, for example, a reference mirror 240, and the driving unit 142 includes For example, the stepping motor 242 that drives the reference mirror 240 is used.

The light source 110 such as the SLD 210 that is the source of the measurement light is light that is transmitted through and reflected from both end faces S ₁ and S ₂ of the wafer Tw that is the measurement object, and is reflected at both end faces S ₁ and S ₂ of the wafer Tw. Use light that can irradiate light that can be reflected back and forth at least twice. For example, since the wafer Tw is formed of silicon, it is preferable to use a light source 110 that can irradiate light having a wavelength of 1.0 to 2.5 μm that can transmit a silicon material such as silicon or a silicon oxide film. .

  As shown in FIG. 5, the substrate processing apparatus 300 includes a processing chamber 310 that performs a predetermined process such as an etching process or a film forming process on the wafer Tw, for example. An upper electrode 350 and a lower electrode 340 facing the upper electrode 350 are disposed inside the processing chamber 310. The lower electrode 340 also serves as a mounting table for mounting the wafer Tw. For example, an electrostatic chuck (not shown) that electrostatically attracts the wafer Tw is provided on the lower electrode 340. The lower electrode 340 is provided with cooling means. This cooling means controls the temperature of the wafer Tw by, for example, controlling the temperature of the lower electrode 340 by circulating the coolant through the coolant channel 342 having a substantially annular coolant channel formed in the lower electrode 340. is there. The wafer Tw is loaded into the processing chamber 310 from a gate valve (not shown) provided on the side surface of the processing chamber 310, for example. The lower electrode 340 and the upper electrode 350 are connected to high-frequency power sources 320 and 330 for applying predetermined high-frequency power, respectively.

  The upper electrode 350 is configured to support an electrode plate 351 located at the lowermost portion thereof with an electrode support 352. The electrode plate 351 is made of, for example, a silicon material (silicon, silicon oxide, etc.), and the electrode support 352 is made of, for example, an aluminum material. An introduction pipe (not shown) through which a predetermined processing gas is introduced is provided above the upper electrode 350. A large number of discharge holes (not shown) are formed in the electrode plate 351 so that the processing gas introduced from the introduction pipe is uniformly discharged toward the wafer Tw placed on the lower electrode 340.

  The upper electrode 350 is provided with cooling means. This cooling means controls the temperature of the upper electrode 350 by circulating a coolant through a coolant channel formed in the electrode support 352 of the upper electrode 350, for example. The refrigerant channel is formed in a substantially annular shape, and is divided into two systems, for example, an outer refrigerant channel 353 for cooling the outside of the upper electrode 350 and an inner refrigerant channel 354 for cooling the inner side. Formed. The outer refrigerant channel 353 and the inner refrigerant channel 354 are supplied from the supply pipe as indicated by the arrows shown in FIG. 5, flow through the refrigerant flow paths 353 and 354, and are discharged from the discharge pipe. It is configured to return to an external refrigerator (not shown) and circulate. The same refrigerant may be circulated in these two refrigerant flow paths, or different refrigerants may be circulated. Note that the cooling means for the upper electrode 350 is not limited to the one having the two refrigerant flow paths shown in FIG. 5, and may be one having only one refrigerant flow path. You may provide the refrigerant | coolant flow path which branches.

  The electrode support 352 is provided with a low heat transfer layer 356 between an outer portion where the outer refrigerant channel 353 is provided and an inner portion where the inner refrigerant channel 354 is provided. Accordingly, heat is hardly transmitted between the outer portion and the inner portion of the electrode support 352 due to the action of the low heat transfer layer 356. Therefore, the refrigerant is controlled by the outer refrigerant passage 353 and the inner refrigerant passage 354, and the outer portion and the inner portion are separated. It is also possible to control the temperature so that the inner part is at a different temperature. Thus, the in-plane temperature of the upper electrode 350 can be controlled efficiently and accurately.

  In such a substrate processing apparatus 300, the wafer Tw is loaded via a gate valve by a transfer arm, for example. The wafer Tw carried into the processing chamber 310 is placed on the lower electrode 340, high frequency power is applied to the upper electrode 350 and the lower electrode 340, and a predetermined processing gas is passed from the upper electrode 350 into the processing chamber 310. Is introduced. As a result, the processing gas introduced from the upper electrode 350 is turned into plasma, and the surface of the wafer Tw is subjected to, for example, an etching process.

Reference light from the optical fiber coupler 220 in the temperature measuring device 200 is adapted to be transmitted reference beam transmission means for example via a collimator optical fiber with F _Z to the reference mirror 240 to the reference beam irradiation position to be irradiated. Further, the measurement light from the optical fiber coupler 220 is transmitted to the measurement light irradiation position irradiated from the lower electrode 340 toward the wafer Tw as the measurement object via the measurement light transmission means, for example, the optical fiber F with a collimator. It has become. Specifically, the collimator-equipped optical fiber F is disposed so that the measurement light is irradiated toward the wafer Tw through a through hole 344 formed in, for example, the center of the lower electrode 340. Note that the position in the in-plane direction of the wafer Tw on which the collimator-equipped optical fiber F is disposed is not the central portion of the wafer Tw as shown in FIG. 5 as long as the measurement light is irradiated onto the wafer Tw. Also good. For example, the collimator-equipped optical fiber F may be disposed so that the measurement light is irradiated to the end of the wafer Tw.

  The control device 400 controls each part of the temperature measuring device 200 and the substrate processing device 300. The control device 400 includes a CPU (central processing unit) 410 constituting the main body, a motor controller 430 for controlling a stepping motor 242 for driving the reference mirror 240 via a motor driver 420, and program data for the CPU 410 to control each part. Through a memory 440 and a buffer 450 constituting a ROM (Read Only Memory) storing a memory, a RAM (Random Access Memory) provided with a memory area used for various data processing performed by the CPU 410, and the like. The output signal from the PD 250 (the measurement result of the interference of light obtained by irradiating the measurement light) and the control signal (for example, drive pulse) output from the motor controller 430 are analog-digital converted and input A / D converter 460 and each part of substrate processing apparatus 300 are controlled. Equipped with a variety of controller 470. The control device 400 may measure the moving position and moving distance of the reference mirror 240 based on a control signal (for example, a driving pulse) of the stepping motor 242 output from the motor controller 430. A linear encoder is attached to the reference mirror 240. Thus, the movement position and movement distance of the reference mirror 240 may be measured based on the output signal from the linear encoder. Further, the motor 242 is not limited to a stepping motor, and a voice coil motor or the like may be used.

  The control device 400 controls the movement of the reference mirror 240 to determine a standard interference waveform and a selective interference waveform to be used for temperature measurement from the interference between the reference light obtained from the PD 250, the measurement light, and the light. The optical path length L of the wafer Tw is measured based on the waveform, and the temperature of the wafer Tw is obtained from the measurement result according to the temperature conversion method as described above. Specifically, for example, the optical path length L of the measurement light on the wafer Tw is converted into temperature based on the above-described temperature conversion reference data stored in the memory 440 in advance. In this respect, the control device 400 constitutes a measuring unit.

  Next, FIG. 6 shows a specific example of light interference between the measurement light and the reference light obtained by the temperature measurement system shown in FIG. FIG. 6 shows an interference waveform between each measurement light as shown in FIG. 2 reflected by the wafer Tw and the reference light reflected by the reference light reflecting means 140. In FIG. 6, the vertical axis represents the interference intensity, and the vertical axis represents the moving distance of the reference mirror.

According to FIG. 6, when the reference mirror 240 continue to scan in one direction, first interference waveform of the measurement light reflected by the first surface S ₁ which constitutes the rear surface of the wafer Tw and the reference beam (first surface once Interference waveform of reflected measurement light or zero-time reciprocation reflected measurement light) y _a0 appears, and then is reflected by the second surface S ₂ constituting the surface of the wafer Tw, and both end surfaces (the first surface S ₁ and the first surface S ₁ of the wafer Tw). An interference waveform (interference waveform of the second surface one-time reflected measurement light or one-time round-trip reflected measurement light) y _a1 appears after the measurement light and the reference light reflected once on the second surface S ₁ ). When the reference mirror 240 is further scanned, the interference waveform between the measurement light and the reference light reflected back and forth twice at both end faces S ₁ and S ₂ of the wafer Tw (second surface twice reflected measurement light or twice round-trip reflection). Interference waveform of measurement light) y _a2 appears, and then the interference waveform of the measurement light and the reference light reflected back and forth three times on both end faces S ₁ and S ₂ of the wafer Tw (second surface three-time reflected measurement light or three times round-trip) Interference waveform of reflected measurement light) y _a3 appears.

Of these interference waveforms, for example, if the first surface once based on the interference waveform _{y a0} of the reflected measuring light, the peak-to-peak width Lw between the reference interference waveform _{y a0} and other interference waveform _y a1 _{~y a3,} 2Lw and 3Lw are 1 time, 2 times and 3 times the optical path length of the measuring light (the optical path length of the wafer Tw) between the surfaces S ₁ and S ₂ constituting the thickness of the wafer Tw, that is, L and 2L, respectively. , 3L. Thus, by selecting the other interference waveform y _a1 ~y _a3 throat interference waveform, it is measured peak-to-peak width of the selected interference waveform and the reference interference waveform y _a0, to determine the optical path length L of the wafer Tw Can do. The reference interference waveform here is an interference waveform used as a reference for obtaining the optical path length L of the measurement object, for example, the wafer Tw. The selected interference waveform is an interference waveform selected for obtaining the optical path length L of the wafer Tw from the peak-to-peak width with respect to the reference interference waveform.

FIG. 7 shows a result of an experiment in which temperature measurement is performed using the interference waveform shown in FIG. 6 and the temperature measurement error is calculated. Specifically, each selection of the interference waveform of the wafer Tw is the measuring light beam obtained when the 40 ° C. and the reference light, an interference waveform y _a0 and the reference interference waveform, other interference waveforms y _a1 ~y _a3 as an interference wave, the peak-to-peak width of the reference interference waveform _{y a0} and each selected interference waveform _y a1 _{~y a3} measured, the measurement of the respective peak width Lw was, 2LW, seeking each optical path length L of the wafer Tw from 3Lw in which it was performed in terms of the temperature range of the temperature measurement processing by 50 times, respectively, were plotted to determine the average of the temperature measurement error when the temperature was measured by using the selected interference waveform y _a1 ~y _a3 is there.

In FIG. 7, the horizontal axis represents the number of reciprocal reflections of the measurement light for each of the selected interference waveforms y _{a1 to} ya ₃ , and the horizontal axis represents the temperature measurement error. The temperature measurement error shown in FIG. 7 is a value determined with 3σ in the case of the standard deviation of 50 times of the temperature data obtained with each selected interference waveform y _a1 ~y _a3 and sigma. Therefore, the larger the value of 3σ as an index of the temperature measurement error, the greater the variation from the actual 40 ° C., and the greater the temperature measurement error. P ₁ shown in FIG. 7 is a temperature measurement error when the temperature was measured as the selected interference waveform interference waveform y _a1, temperature measurement when P ₂ is subjected to temperature measurement as the selected interference waveform interference waveform y _a2 an error, P ₃ is the temperature measurement error when the temperature was measured as the selected interference waveform interference waveform y _a3.

According to the experimental result shown in FIG. 7, the interference waveform when the y _a2 and selected interference waveform towards the (P _2), than (P ₁₎ in which the interference waveform y _a1 and the selected interference waveform, temperature measurement errors It can be seen that is smaller. Therefore, the measurement accuracy of the peak-to-peak width between the reference interference waveform and the selected interference waveform can be improved by selecting the selected interference waveform so that the peak-to-peak width with respect to the reference interference waveform _ya0 is long.

  The peak-to-peak width between the reference interference waveform and the selected interference waveform can be made longer as the interference waveform of the measurement light having a large number of reciprocal reflections at both end faces of the wafer Tw is selected as the selected interference waveform. It is considered that the measurement accuracy of the width can be improved.

However, as the experimental results in the case of performing actual temperature measurements are shown in FIG. 7, for example, for the case where the interference waveform y _a3 and the selected interference waveform (P _3), the interference waveform y _a2 was selected interference waveform but it should take longer peak width of the reference interference waveform and the selected interference waveform than the interference if the waveform y _a2 was selected interference waveform temperature measurement error becomes larger than (P _2), rather the temperature measurement accuracy deteriorates You can see that

  This is because the waveform of the measurement light interference waveform having a large number of reciprocal reflections on both end faces of the wafer Tw is deformed (distorted) due to, for example, a decrease in light intensity (S / N ratio) against noise. This is because a measurement error at the peak position of the waveform is likely to occur. Therefore, if such an interference waveform is selected and the peak-to-peak width from the reference interference waveform is measured, the peak-to-peak width between the selected interference waveform and the reference interference waveform is equal to the measurement error of the peak position of the selected interference waveform. There is also a problem that a measurement error occurs. Note that the noise referred to here may be, for example, noise generated from an electronic circuit or noise due to the surrounding electromagnetic environment when high frequency power is applied to the upper electrode 350.

(Measurement error of peak position of interference waveform)
Here, the measurement error of the peak position of the interference waveform as described above will be described in more detail with reference to the drawings. Figure 8 is a detail of the measured waveform y _a showing, in enlarged to expand the range of movement distance of the reference mirror to one interference waveforms, the processing waveform y _b subjected to predetermined processing to the measured waveform y _a It is the figure which showed the example. The horizontal axis of FIG. 8 is the reference mirror movement distance, the vertical axis is the output voltage (V) from the PD 250 of the measured waveform, and the vertical axis is the Gaussian distribution (normal distribution) range. ing.

As shown in the measured waveform y _a in FIG. 8, the measured waveforms of the interference waveform is composed of a large mountain called respectively wave communication. The wave train is composed of a plurality of repetitive waveforms, and each interference waveform has a mutually independent phase and amplitude.

In order to make it easy to obtain the peak position of the actually measured waveform ya, _a predetermined processing is performed. For example, offset from the waveform data of measured waveform y _a of the interference wave subtracted, to do this the folded back the negative portion to the positive portion by squaring. Then, so the processing waveform y _b shown in FIG.

The entire wave trains of machining waveform y _b of the thus obtained interference waveform curve approximation. As an approximate curve of such a wave train, there is a Gaussian distribution curve (normal distribution curve). The entire wave trains of machining waveform y _b of the interference waveform when approximated by a Gaussian distribution curve to determine the Gaussian distribution (normal distribution), for example, by the method of least squares for the entire waveform data processing waveform y _b. When the Gaussian distribution curve y _c obtained in this way is superimposed on the processing waveform y _b of the interference waveform, it is as shown in FIG. Incidentally, the approximate curve which approximates the entire wave trains of machining waveform y _b of the interference waveform is not limited to the Gaussian distribution curve as described above.

Thus the entire wave trains of machining waveform y _b of the interference waveform is approximated to a Gaussian distribution curve y _c, the center value of the Gaussian distribution curve y _c (peak position) calculated, which the peak position of the interference waveform To do. In this case, for example, processed waveform y _b of the interference waveform is collapsed, since the deviation in the processed waveform y _b a Gaussian distribution curve y _c occurs in the peak position of the machining waveform y _b a Gaussian distribution curve y _c There is a high possibility that a deviation occurs, resulting in an error in the measurement of the peak position of the interference waveform.

The deviation between the machining waveform y _b a Gaussian distribution curve y _c of such interference waveform, an example of the interference waveform as shown in FIG. 6 will be described in more detail. 9 to 12 show the processing waveforms y _{b0 to} y _b3 when the above-described processing is performed on the interference waveforms y _{a0 to} ya ₃ shown in FIG. 9 to 12, the horizontal axis represents the reference mirror moving distance, and the vertical axis represents the amplitude of the machining waveform. In Figure 9-12, as collapse degree straightforward machining waveform y _b0 ~y _b3 interference waveforms, even taking large amplitude of the range of about horizontal axis low interference strength of the interference wave. According to FIGS. 9 to 12, the processed waveforms y _{b0 to} y _b3 of the interference waveform are compared with the Gaussian distribution curves y _{c0 to} y _{c3 in} the order of the processed waveforms y _b0 , y _b1 , y _b2 , and y _b3 of the interference waveform. That is, as the interference waveform of the measurement light having a large number of reciprocal reflections at both end faces S ₁ and S ₂ of the wafer Tw, the shape of the waveform collapses and the deviation from the approximated Gaussian distribution curves y _{c0 to} y _c3 increases. I understand that.

(Judgment method of interference waveform collapse and selection of interference waveform using this)
Then, the degree of deviation between the machining waveform _y b0 _{~y b3} and Gaussian distribution curve _y c0 _{~y c3} interference waveforms shown in FIGS. 9 to 12, as a collapse degree of processing waveform _y b0 _{~y b3} interference waveform A method of quantifying and determining this will be described. Here, in order to quantify the degree of collapse of the processed waveforms y _{b0 to} y _b3 of the interference waveform, for example, the interference waveform is based on the individual repetitive waveforms that form the chain of the interference waveform from the waveform data of the processed waveform of the interference waveform. Is approximated by, for example, an envelope, and the degree of deviation between the envelope and the Gaussian distribution curve is calculated. Note that the approximate curve of the interference waveform based on the individual repetitive waveforms constituting the interference waveform series is not limited to the envelope as described above. For example, a curve obtained by smoothly connecting values obtained by integrating individual repetitive waveforms constituting a wave series of interference waveforms may be used as an approximate curve of the interference waveform.

Here, the envelopes y _{d0 to} y _d3 approximating the processed waveforms y _{b0 to} y _b3 of the interference waveforms shown in FIGS. 9 to 12 and the Gaussian distribution curves y _{c0 to} y _c3 are overlapped, respectively. As shown in FIG. In FIGS. 13 to 16, the envelopes y _{d0 to} y _d3 of the interference waveform are represented by solid lines, and the approximated Gaussian distribution curves y _{c0 to} y _c3 are represented by dotted lines.

According to FIGS. 13 to 16, it is well understood that the peak portions are broken in the order of envelopes y _d0 , y _d1 , y _d2 , and y _d3 , and the envelope and the Gaussian distribution curve are shifted. This is because the envelope of the interference waveform of the measurement light having a large number of reciprocal reflections at both end faces S ₁ and S ₂ of the wafer Tw is shifted from the envelope and the Gaussian distribution curve. The position is also shifted.

The degree of deviation between the machining waveform y _b a Gaussian distribution curve y _c of such interference waveform can be quantified by an index, such as for example the following. The waveform data of the envelope y _d of the interference waveform in a position m which a reference mirror moving distance and V (m), the intensity of the Gaussian distribution curve y _c at the same position m and G (m), of a Gaussian distribution curve y _c The intensity at the peak position (peak intensity) is Gp. A value obtained by taking the absolute value of G (m) −V (m) and dividing it by the peak intensity Gp of the Gaussian distribution curve y _c is k (m).

K (m) is thus obtained, determined for waveform data of all the machining waveform y _b in the range of the reference mirror moving distance approximating the working waveform y _b of the interference waveform with a Gaussian distribution curve y _c, the average value K of the whole _{Let AVE be} an index K of the degree of collapse of the interference waveform.

The index K of collapse degree of such interference waveforms, the degree of deviation of the envelope y _d and the Gaussian distribution curve y _c of larger the value of the interference waveform increases, collapsing the degree of interference waveform becomes large. For this reason, for example, if the index K of the degree of collapse of the interference waveform is obtained for each interference waveform shown in FIGS. 13 to 16, the degree of collapse of the interference waveform can be quantitatively determined.

Here, FIG. 17 shows the result of obtaining the collapse degree index K for the envelopes y _{d0 to} y _d3 of the interference waveforms y _{a0 to} y _a3 shown in FIGS. 13 to 16. In Figure 17, taking the reciprocal number of reflections of the measurement light on the interference waveform y _a1 ~y _a3 used in the temperature measurement on the horizontal axis, taking an indication K of the collapse degree of interference waveforms on the horizontal axis. K _{0 to} K ₃ shown in FIG. 17 are the interference waveform y _a0 of the first surface once reflected measurement light, the interference waveform ya ₁ of the second surface once reflected measurement light, and the interference of the second surface twice reflected measurement light, respectively. The waveform y _a2 is an indicator of the degree of collapse of the interference waveform _ya 3 of the second-surface three-time reflected measurement light.

According to the experimental results shown in FIG. 17, the indicators K _{0 to} K _{2 for the} degree of collapse of the interference waveform show substantially the same low values, and become larger at the index K ₃ for the degree of collapse of the interference waveform. That is, the interference waveform y _a0 of the first surface once reflected measurement light, the interference waveform y _a1 of the second surface once reflected measurement light, and the interference waveform _ya 2 of the second surface twice reflected measurement light are interfering with the interference waveform and Gaussian. Since the deviation from the distribution is small and there is almost no disruption of the interference waveform, it can be seen that the measurement error of the peak position of the interference waveform is also small. On the other hand, for the interference waveform _ya3 of the second-surface three-time reflected measurement light, the deviation between the interference waveform and the Gaussian distribution is large, the interference waveform collapses, and the measurement error of the peak position of the interference waveform is also large. I understand that.

In this manner, the peak-to-peak width between the reference interference waveform and the selected interference waveform is increased as the interference waveform of the measurement light that is frequently reciprocated at both end faces S ₁ and S ₂ of the wafer Tw is selected as the selected interference waveform. On the other hand, such a disruption of the selected interference waveform increases, and the measurement error of the peak position of the selected interference waveform also increases. Therefore, it is preferable to determine the interference waveform selected for measuring the peak-to-peak width with the reference interference waveform according to the degree of collapse of the interference waveform.

In this regard, if the index K of the degree of collapse of the interference waveform as described above is used, a range in which the degree of collapse of the interference waveform does not become so large as to affect the temperature accuracy (eg, the degree of collapse of the interference waveform is a measurement of the peak-to-peak width of the interference waveform). It is possible to easily select an interference waveform that can take a longer peak-to-peak width between the reference interference waveform and the selected interference waveform within a range in which the accuracy is not lowered. For example, in the case shown in FIG. 17, the interference waveform having the largest number of round-trip reflections, that is, the index of the degree of collapse of the interference waveform is K ₂ within a range where the degree K of collapse of the interference waveform does not exceed a predetermined value (for example, 0.04). The second-surface twice reflected measurement light interference waveform _ya2 is selected as the selected interference waveform. The reference interference waveform is obtained by approximating the waveform of the selected interference waveform _ya2 and the reference interference waveform _ya0 selected in this way to a Gaussian distribution curve to determine the peak position and measuring the peak-to-peak width which is the width of these peak positions. And the measurement accuracy of the peak-to-peak width of the selected interference waveform can be improved accurately.

  It should be noted that each processing such as calculation of the peak position of the interference waveform, measurement of the peak-to-peak width of the interference waveform, calculation of the index K of the collapse degree of the interference waveform, selection of the interference waveform used for temperature measurement as described above is controlled. The CPU 410 of the device 400 can execute based on a program.

According to the temperature measurement system according to the second embodiment as described above, by irradiating the measurement light from one side of the wafer Tw, a plurality of measurement light and reference light reflected from the wafer Tw and returned. The interference waveform (light interference) is received by the PD 250. A reference interference waveform interference waveform of the measurement light reflected by the first surface S ₁ of one example wafer Tw of these interference waveforms, both end faces S _1, S ₂ in the measurement of round trip reflected more than once wafer Tw By determining the peak-to-peak width between the reference interference waveform and the selected interference waveform using light as the selected interference waveform, the peak-to-peak width between the reference interference waveform and the selected interference waveform can be increased. The amount of change in the peak-to-peak width can also be increased. Thereby, the measurement accuracy of the peak-to-peak width of each interference waveform can be improved.

  In particular, when the optical path length of the measurement light between both end faces of the measurement target is small (for example, when a thin semiconductor wafer or the like is the measurement target), the width of the reference interference waveform and the selected interference waveform is increased. As a result, the measurement accuracy of the peak-to-peak width of these interference waveforms can be greatly improved. Thereby, since the measurement accuracy of the optical path length of the measurement light between both end faces of the measurement object can be improved, the measurement accuracy of temperature or thickness can also be improved.

  Further, the selected interference waveform is selected based on the index K of the degree of collapse of the interference waveform, so that it can be selected as the reference interference waveform within a range in which the degree of collapse of the interference waveform does not reduce the measurement accuracy of the peak-to-peak width of the interference waveform. It is possible to easily select an interference waveform that can have a longer width from the interference waveform.

Note that the reference interference waveform, has been described relative to the measurement light interference waveform reflected by the first surface S ₁ of the object to be measured for example wafer Tw, not necessarily limited thereto, in PD250 Any of a plurality of measured interference waveforms may be used as a reference. Even in such a case, the reference interference waveform and the selected interference waveform are obtained by setting the interference waveform of the measurement light that reciprocally reflects at both ends of the wafer Tw at least twice more than the measurement light of the reference interference waveform as the selective interference waveform. The peak-to-peak width can be longer than twice the optical path length of the measurement light between both end faces of the wafer Tw. This is because the measurement accuracy of the peak-to-peak width of the interference waveform can be improved.

(Temperature measuring device according to the third embodiment)
Next, a temperature measurement system for a substrate processing apparatus according to a third embodiment will be described with reference to the drawings. The temperature measurement system according to the third embodiment is configured by improving the temperature measurement system according to the second embodiment so that the moving distance of the reference mirror can be further shortened.

  As described above, the temperature measurement system according to the second embodiment selects the interference waveform of the measurement light that reciprocates twice or more at both end faces of the wafer w, which is the measurement target T, than the measurement light of the reference interference waveform. An interference waveform is obtained, and the optical path length L of the wafer Tw is obtained based on the peak-to-peak width of the selected interference waveform and the reference interference waveform.

  However, as the interference waveform of the measurement light that is reflected back and forth more than once at both end faces of the wafer w is selected, the peak-to-peak width of the selected interference waveform and the reference interference waveform becomes longer, and the reference mirror 240 is moved accordingly. The distance must also be increased. If the moving distance of the reference mirror 240 is long, it takes time to measure the temperature accordingly, so the moving distance of the reference mirror 240 is preferably as short as possible.

  The temperature measurement system according to the third embodiment is improved based on this point. As an improvement, for example, a detour optical path connected in parallel to the optical path of the measurement light is provided in the middle of the optical path of the measurement light constituting the measurement light transmission means. As a result, both the measurement light that passes through the detour optical path and the measurement light that does not pass are irradiated toward the measurement object. Therefore, the type of interference (pattern) of the light to which the plurality of interference waveforms of the measurement light and the reference light belong. Can be increased. As a result, for example, the interference waveform of the measurement light that is reflected back and forth the same number of times on both end faces of the measurement object T passes through the optical path that does not pass through the bypass optical path, and passes through the optical path that passes through the bypass optical path at least once. Can be measured.

  Therefore, by adjusting the optical path length of the detour optical path and adjusting the shift amount of the interference of each light, the interference belonging to the interference of the light passing through one of the optical paths among the interference waveforms measured as described above. The reference interference waveform selected from the waveform and the selected interference waveform selected from the interference waveform belonging to the interference of light passing through the other optical path can be measured in the vicinity. For this reason, it is sufficient to move the reference mirror 240 at least within a range in which the reference interference waveform and the selected interference waveform can be measured. Thereby, since the moving distance of the reference mirror 240 can be shortened, the time required for measuring the temperature of the wafer Tw can also be shortened.

  A specific configuration example of such a temperature measurement system according to the third embodiment is shown in FIG. The measurement light transmission means in the temperature measurement system shown in FIG. 18 is a bypass optical path connecting splitter for connecting in parallel the optical fiber e constituting the bypass optical path in the middle of the optical path of the measurement light from the optical fiber coupler 220, for example 2 × Two optical fiber couplers 230 are provided. The optical fiber coupler 230 has the same configuration as the optical fiber coupler 220.

One output terminal (output port) from the optical fiber coupler 220 is connected to one input terminal (input port) of the optical fiber coupler 230 via the optical fiber b. To one output terminal of the optical fiber coupler 230 (the output port), an optical fiber b _F collimator optical fiber with F fitted with a collimator at the tip of the are connected. Further, the other input terminal (input port) and the other output terminal (output port) of the optical fiber coupler 230 connect the optical fiber e constituting the bypass optical path to form a loop.

According to the measurement light transmission means configured as shown in FIG. 18, the measurement light emitted from one output terminal (output port) from the optical fiber coupler 220 is output by the optical fiber coupler 230 to two output terminals (output ports). Is divided into two. Measuring light from the out one of the output terminals (output ports) are irradiated from the distal end of the optical fiber F with collimators to the wafer Tw through the optical fiber b _F.

Further, the measurement light from the other output terminal (output port) of the optical fiber coupler 230 is returned to the other input terminal (input port) of the optical fiber coupler 230 via the optical fiber e. Divided into two output terminals (output ports). Measuring light from the out one of the output terminals (output ports) are irradiated from the distal end of the optical fiber F with collimators to the wafer Tw through the optical fiber b _F.

In this way, by providing a bypass optical path connected in parallel in the middle of the optical path of the measurement light that constitutes the measurement light transmission means, the measurement light split from the SLD 210 is directed from the collimated optical fiber F toward the wafer Tw. In addition to the forward path irradiated, the return path in which the measurement light reflected from the wafer Tw is received via the collimator-equipped optical fiber F passes through the path via the optical path U ₁ in the optical fiber coupler 230, or the optical fiber. since or through the path through the bypass optical path U ₂ by e, the type of the optical path of the measuring beam (pattern) is increased. As a result, the types (patterns) of interference of light to which a plurality of interference waveforms of the measurement light and the reference light belong are also increased.

  Here, the optical path of such measurement light will be described with reference to the drawings. FIG. 19 shows the relationship between the type (pattern) of the optical path of the measurement light and the path of the measurement light at that time. The measurement light path includes an outward path from the output from the optical fiber coupler 220 to the irradiation to the wafer Tw and a return path from the reflection from the wafer Tw to the input of the measurement light to the optical fiber coupler 220.

The types (patterns) of the optical paths of the measurement light when the detour optical path as shown in FIG. 18 is formed are four combinations from the optical path A to the optical path D as shown in FIG. . Optical path A is a case where the measurement light passes through the path through the forward path and the backward path both optical path U _1, the optical path length is shortest optical path. Optical path B, the forward measurement light passes through a path through the optical path U _1, the return path is a case where through the path via the bypass optical path U _2. Optical path C is measurement light forward path through the path through the bypass optical path U _2, return is when passing through a path through the optical path U _1, is the same length as the optical path B as the optical path length. The optical path D is a case where the measurement light passes through the path through the detour optical path U _{2 in} both the forward path and the return path, and is the optical path having the longest optical path length.

  Here, FIG. 20 shows light interference between the measurement light and the reference light that have passed through the optical paths A to D. FIG. 20 shows an interference waveform obtained when the reference mirror is scanned only once in one direction. The horizontal axis represents the moving distance of the reference mirror, and the vertical axis represents the interference intensity. In FIG. 20, the light interferences caused by the light paths A to D are shifted up and down so that the light interferences can be easily distinguished. The combined waveform thus received is received by the PD 250.

As shown in FIG. 20, the interference of the light along the optical paths A to D is similar to the case shown in FIG. 6, the interference waveform y _a0 of the first surface once reflected measurement light, the second surface once reflected measurement light. An interference waveform y _a1 , an interference waveform y _a2 of the second surface twice reflected measurement light, and an interference waveform _ya 3 of the second surface three reflected measurement light appear at equal intervals. For this reason, the actual interference of the light is a combination of the interferences of the light beams A to D. Therefore, the combined interference waveform of each light has a reference interference waveform (for determining the optical path length L of the wafer Tw ( For example, a plurality of y _a0 ) and selected interference waveforms (for example, y _a2 ) appear.

Further, since the optical paths A to D have different optical path lengths, the light interference caused by the optical paths A to D is shifted according to the optical path lengths of the optical paths A to D, respectively. In example where the reference mirror 240 from the peak appears in the interference waveform y _a0 for the light interference due to the optical path A is moved by a distance M _1, peak appears in the interference waveform y _a0 for the light interference due to the optical path B and the optical path C . The peaks of the interference waveform y _a0 of the optical path D appears at the reference mirror 240 from the peak appears in the interference waveform y _a0 for the light interference due to the optical path A is moved by a distance M _2. This is because the optical path length of the optical path A is the shortest, so that the first interference waveform _{ya 0} regarding the light interference by the optical path A appears most quickly, whereas the optical path lengths of the optical paths B, C, and D are longer than the optical path A. This is because the interference of these lights is shifted by the difference in the length of the optical path length, and the first interference waveform _ya0 appears. Since the optical path lengths of the optical path B and the optical path C are the same, the first interference waveform _ya0 regarding the interference of these lights appears simultaneously.

Moreover, the amount of deviation of the light interference caused by the optical paths A to D is adjusted by adjusting the optical path length of the detour optical path of the measurement light (for example, the length of the optical fiber e). Can be adjusted. Therefore, by adjusting the optical path length (for example, the length of the optical fiber e) of the detour optical path of the measurement light, the reference interference waveform belonging to the light interference by one optical path and the selective interference belonging to the light interference by another optical path. The waveform can appear in the vicinity. For example, when the interference waveform _ya0 is the reference interference waveform and the interference waveform _ya2 is the selected interference waveform, the vicinity of the selected interference waveform _ya2 belonging to the light interference by the optical path A in the combined waveform of each light shown in FIG. Thus, the reference interference waveform _ya0 belonging to the interference of light by another optical path B can also appear.

What is obtained by adding a deviation amount (for example, M) of the reference interference waveform belonging to the optical interference by each optical path to the peak-to-peak width (for example, M _S ) of the reference interference waveform and the selected interference waveform respectively belonging to such different light interference This corresponds to the peak-to-peak width (for example, 2 Lw) of the reference interference waveform and the selected interference waveform that belong to light interference by one type of optical path.

In addition, if the position of the reference interference waveform does not change when the temperature of the wafer Tw changes, the deviation amount M of the reference interference waveform belonging to the interference of each light corresponds to the deviation amount of the interference of each light (for example, M ₁ ). The deviation amount M is constant before and after the temperature change of the wafer Tw. On the other hand, since the position of the interference waveform of the selected interference waveform changes when the temperature of the wafer Tw changes, the peak-to-peak width (for example, M _S ) of each of the reference interference waveform and the selected interference waveform belonging to different light interferences is the temperature. It changes before and after the change.

Therefore, according to the temperature measurement system in the present embodiment, when the amount of deviation M of the reference interference waveform belonging to the interference of each light is measured in advance and the temperature of the wafer Tw is actually measured, it is shown in FIG. only measures the width M _S between the peaks of the reference interference waveform and the selected interference waveform that best appearing in the vicinity of a synthetic waveform of the interference of the light, such as, one reference interference waveforms belonging to the interference of light due to the optical path of the selected interference waveform The peak-to-peak width (for example, 2 Lw) can be calculated. Then, the temperature of the wafer Tw can be measured by obtaining the optical path length L of the wafer Tw based on this peak-to-peak width and converting it to a temperature.

For this reason, if the reference mirror 240 is moved within a range in which the peak-to-peak width (for example, M _S ) between the reference interference waveform and the selected interference waveform that appear closest in the combined waveform of the interference of each light can be measured, the temperature of the wafer Tw. Can be measured. Accordingly, the distance between the reference mirror and the selected interference waveform, which belongs to the interference of light by one type of optical path, can be made shorter than the distance by which the reference mirror is moved to measure the temperature of the wafer Tw. Such time can also be shortened.

  The deviation amount M of the reference interference waveform of the interference of each light is measured before, for example, measuring the temperature of the wafer Tw, and is stored in, for example, the memory 440 of the control device 400, and actually the wafer Tw. Take out and use when measuring the temperature.

In addition, the reference interference waveform according to the present embodiment is based on an interference waveform in which the deviation amount M of the reference interference waveform of each light interference does not change as much as possible due to the temperature change of the wafer Tw as the measurement target T. Is preferred. Thereby, the frequency of measuring the deviation amount M of the reference interference waveform of the interference of each light can be reduced. For example, the first surface S ₁ which constitutes the rear surface of the wafer Tw, even if the temperature of the wafer Tw is changed because it is placed on the lower electrode 340, the back surface position of the wafer Tw is hardly changed. In contrast, the second surface S ₂ constituting the surface of the wafer Tw is free to its position is changed by the temperature change of the wafer Tw since faces the space. Therefore, it is preferable that the basis of the interference waveform of the measurement light reflected back surface of the wafer Tw as interference waveform y _a0.

However, even when the interference waveform _ya0 reflected from the back surface of the wafer Tw is used as the reference interference waveform, the position of the reference interference waveform may change due to environmental changes such as the ambient temperature of the wafer Tw. In such a case, the deviation amount M of the reference interference waveform belonging to the light interference caused by different optical paths may be measured each time the environment of the wafer Tw changes. Even in this case, measurement frequency shift amount M of reference interference waveform, it is considered that much less compared to the measurement frequency of the peak-to-peak width M _S of the interference waveforms, the time required for temperature measurement of the wafer Tw There is an effect of shortening.

  In addition, as a reference interference waveform in the present embodiment, if it appears closest to the selected interference waveform in the combined waveform of each light interference, it appears on either side of the selected interference waveform before or after the reference mirror moving distance. It may be used.

When using the reference interference waveform y _a0 appearing on the rear side of the reference mirror moving distance of the selected interference waveform y _a2 as shown in FIG. 20 obtains a peak-to-peak width 2Lw of each interference waveform example, the selection interference waveform y _a2 By making the peak-to-peak width M _S with the reference interference waveform _{ya 0} closest to the positive value and adding the deviation amount M of the reference interference waveform _{ya 0} belonging to the interference of each light to the peak-to-peak width M _S , a desired value is obtained. The peak-to-peak width 2Lw can be obtained.

In contrast, although not shown, in case of obtaining the peak-to-peak width 2Lw of each of the interference waveform with the reference interference waveform y _a0 appearing on the front side of the reference mirror moving distance of the selected interference waveform y _a2, the selected interference waveform By making the peak-to-peak width M _S with the reference interference waveform y _a0 closest to y _{a2 a} negative value, and adding the deviation amount M of the reference interference waveform _{ya 0} belonging to the interference of each light to the peak-to-peak width M _S , A desired peak-to-peak width 2Lw can be obtained.

(Modification of the temperature measurement system according to the third embodiment)
Next, a modification of the temperature measurement system according to the third embodiment will be described with reference to the drawings. FIG. 21 is a block diagram illustrating a schematic configuration of a modification of the temperature measurement system according to the third embodiment. The temperature measurement system shown in FIG. 21 is substantially the same as that shown in FIG. 18, but the one shown in FIG. 18 uses an optical fiber coupler 230 to parallel the optical fiber e constituting the detour optical path in the optical path of the measurement light. 21 to form a loop, while the one shown in FIG. 21 has two splitters (for example, a 1 × 2 optical fiber coupler 232 and a 2 × 1 optical fiber coupler 234) as detour optical path connecting splitters, The optical fiber e ₁ constituting the optical path of the measurement light and the optical fiber e ₂ constituting the bypass optical path are connected in parallel to form a loop. Accordingly, the temperature measurement system shown in FIG. 21 can also be provided with a bypass optical path connected in parallel in the middle of the optical path of the measurement light constituting the measurement light transmission means, similar to that shown in FIG.

More specifically, one output terminal (output port) from the optical fiber coupler 220 is connected to the input terminal (input port) of the 1 × 2 optical fiber coupler 232 shown in FIG. It is connected. The two output terminals (output ports) of the 1 × 2 optical fiber coupler 232 respectively have one end of a short optical fiber e ₁ forming a path U ₁ and a path U ₂ of a bypass optical path longer than the optical fiber e _1. and one end of the optical fiber e ₂ that forms is connected. The other end of the optical fiber e _{1 and} the other end of the optical fiber e ₂ are respectively connected to two input terminals (input ports) of a 2 × 1 optical fiber coupler 234. Optical fiber b _F collimator optical fiber with F fitted with a collimator to the tip of the output terminal (output port) of the 2 × 1 optical fiber coupler 234 is connected.

According to the measurement light transmission means configured as shown in FIG. 21, the measurement light emitted from one output terminal (output port) from the optical fiber coupler 220 is output by the optical fiber coupler 232 to two output terminals (output ports). Is divided into two. Among these, the measurement light from one output terminal (output port) enters the input terminal (input port) of the optical fiber coupler 234 through the short optical fiber e ₁ . On the other hand, the measurement light from the other output terminal (output port) of the optical fiber coupler 232 enters the input terminal (input port) of the optical fiber coupler 234 through the optical fiber e ₂ constituting the bypass optical path. In the optical fiber coupler 234, the measurement light from the optical fiber e ₁ and the optical fiber e ₂ is multiplexed, is irradiated from the tip of the collimator optical fiber with F the wafer Tw.

Note that the relationship between the type of optical path of the measurement light (optical paths A to D) by the measurement light transmission means configured as shown in FIG. 21 and the path of the measurement light at that time is the same as that shown in FIG. The light interference between the measurement light and the reference light when the light passes through the optical paths A to D is the same as that shown in FIG. That is, also in the temperature measurement system having the configuration shown in FIG. 21, the deviation amount of the interference between the measurement light and the reference light when passing through each of the optical paths A to D is the optical path length (for example, optical fiber) of the detour optical path of the measurement light. e ₁ and the length of the optical fiber e ₂ ) to adjust the optical path lengths of the optical paths A to D.

Accordingly, by adjusting the optical path length of the detour optical path of the measurement light (for example, the length of the optical fiber e ₁ or the optical fiber e ₂ ), the selected interference waveform (for example, ya ₂ ) respectively belonging to the interference of light by different optical paths A reference interference waveform (for example, y _a0 ) can appear in the vicinity in the combined waveform of interference of each light. For this reason, even in the modification of the present embodiment, the peak-to-peak width (for example, M _S ) of the reference interference waveform (for example, y _a0 ) and the selected interference waveform (for example, y _a2 ) that appear closest to each other in the combined waveform of light interference. If the reference mirror 240 is moved within the measurable range, the temperature of the wafer Tw can be measured. Thereby, since the moving distance of the reference mirror can be shortened, the time required for measuring the temperature of the wafer Tw can also be shortened.

Further, the optical fiber e constituting the bypass optical path shown in FIG. 18 described above connects the other input terminal (input port) and the other output terminal (output port) of one optical fiber coupler 230 to form a loop. Since it is formed, it is necessary to bend and arrange the optical fiber e, which may not be suitable depending on the length and thickness of the optical fiber. For example, when the optical fiber is short or thick, it is difficult to bend and arrange. On the other hand, the optical fiber e ₂ constituting the detour optical path shown in FIG. 21 is connected to the middle of the two optical fiber couplers 232 and 234, and therefore does not need to be bent extremely. Nevertheless, the arrangement is easy.

Moreover, in the case shown in FIG. 18, the optical path length of the measurement light is adjusted by adjusting the length of the optical fiber e constituting the bypass optical path, whereas in the case shown in FIG. 21, the bypass optical path is configured. Since not only the length of the optical fiber e ₂ to be measured but also the length of the optical path itself of the measurement light can be adjusted by the length of the optical fiber e ₁ , fine adjustment of the optical path lengths of the optical paths A to D of the measurement light is easy. Can be done.

(Temperature measurement system according to the fourth embodiment)
Next, a temperature measurement system for a substrate processing apparatus according to a fourth embodiment will be described with reference to the drawings. The temperature measurement system according to the fourth embodiment is configured by improving the temperature measurement system according to the second embodiment so that the moving distance of the reference mirror can be further shortened. In the third embodiment described above, the optical path length of the measurement light is adjusted, whereas in the fourth embodiment, the optical path length of the reference light is adjusted.

FIG. 22 shows a configuration example of such a temperature measurement system according to the fourth embodiment. In the temperature measurement system shown in FIG. 22, the reference mirror 240 is configured by a first reference mirror 244 and a second reference mirror 246 that have different reflection surface positions. Reference light from the reference light transmitting means such as optical fiber F _Z with collimator is a first and a collimator optical fiber with F _Z to the reference light irradiation position irradiated to both the second reference mirror 244 arranged, each reference receiving reference light reflected from the mirror 244, 246 in the same collimator optical fiber with _{F Z.}

According to the temperature measurement system with such a configuration, the reference to be irradiated with first and second reference mirror 244 by moving together by the stepping motor 242, it is split from the collimator optical fiber with F _Z from SLD210 When light is reflected by the reference mirror 240, the first reference light passing through the optical path E reflected from the first reference mirror 244 and the second reference light passing through the optical path F reflected from the first reference mirror 246 Since they are divided, it is possible to measure the light interference between the two types of measurement light and the reference light.

  Here, FIG. 23 shows light interference between the measurement light and the reference light that have passed through the optical paths E and F. FIG. 23 shows an interference waveform obtained when the reference mirror 240 is scanned only once in one direction together with the first and second reference mirrors 244 and 246. The horizontal axis represents the moving distance of the reference mirror, and the vertical axis represents the interference intensity. In FIG. 23, the light paths E and F are shifted up and down so that the light interferences can be easily distinguished. In practice, however, the light interference waveforms due to these light paths E and F are all shown in the bottom row. The synthesized waveform is received by the PD 250.

As shown in FIG. 23, the interference of light by the optical paths E and F is similar to the case shown in FIG. 6, the interference waveform y _a0 of the first surface once reflected measurement light, and the interference of the second surface once reflected measurement light. The waveform y _a1 , the interference waveform y _a2 of the second-surface twice reflected measurement light, and the interference waveform _ya 3 of the second-surface three-time reflected measurement light appear at equal intervals. For this reason, since the actual interference of the light is a combination of the light interferences by the optical paths E and F, the combined interference waveform of each light has a reference interference waveform (for determining the optical path length L of the wafer Tw ( For example, a plurality of y _a0 ) and selected interference waveforms (for example, y _a2 ) appear.

  Moreover, the amount of optical interference shift M due to each of the optical paths E and F is adjusted, for example, by adjusting the amount of shift of the reflecting surfaces of the reference mirrors 244 and 246 to obtain the optical path lengths of the optical paths E and F of the first and second reference waves. It can be adjusted by adjusting. Therefore, by adjusting the optical path lengths of the optical paths E and F of the first and second reference lights, the reference interference waveform selected from the interference waveforms of the reference light reflected from one of the reflecting surfaces and the measurement light is different from the reference interference waveform. It is possible to measure the reference light reflected from the reflection surface and the selected interference waveform selected from the interference waveform of the measurement light in the vicinity. For this reason, it is sufficient to move the reference mirror 240 at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference mirror 240 can be shortened, the time required for measuring the temperature of the wafer Tw can also be shortened.

For example, when the interference waveform _ya0 is the reference interference waveform and the interference waveform _ya2 is the selected interference waveform, the vicinity of the selected interference waveform _ya2 belonging to the light interference by the optical path E in the combined waveform of each light shown in FIG. Thus, the reference interference waveform _ya0 belonging to the interference of light by another optical path F can also appear. If the peak-to-peak width (for example, M _S ) of these interference waveforms is measured, the amount of light transmitted through one type of optical path can be determined by simply adding the deviation amount M of the reference interference waveform belonging to the interference of each light to the peak-to-peak width M _S. peak width 2Lw the reference interference waveform y _a0 belonging to interfere with selective interference waveform y _a2 can be obtained. Then, the temperature of the wafer Tw can be measured by obtaining the optical path length L of the wafer Tw based on the inter-peak width 2Lw and converting it to a temperature.

(Modification of Temperature Measurement System According to Fourth Embodiment)
Next, a modification of the temperature measurement system according to the fourth embodiment will be described with reference to the drawings. FIG. 24 is a block diagram illustrating a schematic configuration of a modification of the temperature measurement system according to the fourth embodiment. The temperature measurement system shown in FIG. 24 is substantially the same as that shown in FIG. 22, but the one shown in FIG. 22 adjusts the optical path lengths of the first and second reference lights by shifting the reflecting surface of the reference mirror. 24, for example, the reference light split from the SLD 210 by the light source side splitter, for example, a 2 × 2 optical fiber coupler 220, is used as the first reference by the reference light splitter, for example, the 1 × 2 optical fiber coupler 222. The light and the second reference light are divided into two parts, and the reference mirror 240 is irradiated with the first and second reference lights to receive the reflected light. It is different in adjustment.

More specifically, the other output terminal (output port) from the optical fiber coupler 220 is connected to the input terminal (input port) of the 1 × 2 optical fiber coupler 222 shown in FIG. It is connected. Mounting each of the 1 × 2 of two output terminals of the optical fiber coupler 222 (output port), the optical fiber c collimator optical fiber with F _Z1 fitted with a collimator tip of _Z1, a collimator at the tip of the optical fiber c _Z2 The collimator-equipped optical fiber _FZ2 is connected.

According to the reference light transmission means configured as shown in FIG. 24, the measurement light emitted from the other output terminal (output port) from the optical fiber coupler 220 is output by the optical fiber coupler 222 to two output terminals (output ports). Is divided into two. Of these, the first reference light from one output terminal (output port) is irradiated toward the reference mirror 240 by the optical path G through the collimator-equipped optical fiber _FZ1, and the second reference from the other output terminal (output port). The light is irradiated toward the reference mirror 240 by the optical path H through the collimator-equipped optical fiber _FZ2 .

Note that the interference between the reference light and the measurement light by the reference light transmission unit configured as shown in FIG. 24 is the same as that shown in FIG. That is, for even temperature measurement system of the configuration shown in FIG. 24, the length of each optical path E, the deviation amount M1 of light interference by F, for example optical fiber _{c Z1, c Z2} of optical fiber with collimator _{F Z1, F Z2} Is adjusted to adjust the optical path lengths of the optical paths E and F of the first and second reference waves.

Therefore, by adjusting the optical path lengths of the first and second reference lights (for example, the lengths of the optical fibers c _Z1 and c _Z2 ), any one of the plurality of reference lights split from the reference light splitter 222 is selected. The reference interference waveform selected from the interference waveform of the reference light and the measurement light and the selected interference waveform selected from the interference waveform of another reference light and the measurement light can be measured in the vicinity. For this reason, it is sufficient to move the reference mirror 240 at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference mirror 240 can be shortened, the time required for measuring the temperature of the wafer Tw can also be shortened.

(Other Modifications of Temperature Measurement System According to Fourth Embodiment)
Next, another modification of the temperature measurement system according to the fourth embodiment will be described with reference to the drawings. In the third embodiment described above, a bypass optical path connected in parallel to the optical path of the measurement light is provided in the middle of the optical path of the measurement light that constitutes the measurement light transmission means. In another modification, a bypass optical path connected in parallel is provided in the middle of the optical path of the reference light constituting the reference light transmission means.

  Even in this configuration, since both the reference light passing through the detour optical path and the reference light not passing through are radiated toward the reference mirror 240, the measurement light and the reference light are similar to those in the third embodiment. The interference pattern of light can be increased, and the reference interference waveform used for the temperature measurement of the wafer Tw and the selected interference waveform are close by adjusting the optical path length of the detour optical path and adjusting the deviation amount of the interference of each light. Can appear in Thereby, the moving distance of the reference mirror can be further shortened.

  Hereinafter, a specific configuration of a temperature measurement system according to another modification of the fourth embodiment is shown in FIG. 25 or FIG. The temperature measurement system shown in FIG. 25 is an example in which a bypass optical path is connected as in the case shown in FIG. That is, the reference light transmission means in the temperature measurement system shown in FIG. 25 is a bypass optical path connecting splitter for connecting in parallel the optical fiber e constituting the bypass optical path in the middle of the optical path of the reference light from the optical fiber coupler 220. A 2 × 2 optical fiber coupler 230 is provided.

Specifically, the other output terminal (output port) from the optical fiber coupler 220 is connected to one input terminal (input port) of the optical fiber coupler 230 via the optical fiber c. To one output terminal of the optical fiber coupler 230 (the output port), the optical fiber c _Z tip collimator optical fiber with F _Z fitted with collimator the are connected. Further, the other input terminal (input port) and the other output terminal (output port) of the optical fiber coupler 230 connect the optical fiber e constituting the bypass optical path to form a loop.

According to the reference light transmission means configured as shown in FIG. 25, the reference light emitted from the other output terminal (output port) from the optical fiber coupler 220 is output by the optical fiber coupler 230 to two output terminals (output ports). Is divided into two. Reference light from these one output terminal (output port) is irradiated from the tip of the optical fiber F _Z with collimator to the reference mirror 240 passes through the optical fiber c _Z. Further, the reference light from the other output terminal (output port) of the optical fiber coupler 230 is returned to the other input terminal (input port) of the optical fiber coupler 230 via the optical fiber e. Divided into two output terminals (output ports). Reference light from these one output terminal (output port) is irradiated from the tip of the optical fiber F _Z with collimator to the reference mirror 240 passes through the optical fiber c _Z.

On the other hand, the temperature measurement system shown in FIG. 26 is an example in which a bypass optical path is connected as in the case shown in FIG. That is, the bypass optical path is composed of two splitters (for example, a 1 × 2 optical fiber coupler 232 and a 2 × 1 optical fiber coupler 234) as the bypass optical path connecting splitter, and the optical fiber e ₁ that forms the optical path of the reference light. by connecting the optical fiber e ₂ in parallel to form a loop. Thereby, also in the temperature measurement system shown in FIG. 26, a bypass optical path connected in parallel in the middle of the optical path of the reference light constituting the reference light transmission means can be provided as in the case shown in FIG.

More specifically, the other output terminal (output port) from the optical fiber coupler 220 is connected to the input terminal (input port) of the 1 × 2 optical fiber coupler 232 shown in FIG. It is connected. The two output terminals (output ports) of the 1 × 2 optical fiber coupler 232 respectively have one end of a short optical fiber e ₁ forming a path U ₁ and a path U ₂ of a bypass optical path longer than the optical fiber e _1. and one end of the optical fiber e ₂ that forms is connected. The other end of the optical fiber e _{1 and} the other end of the optical fiber e ₂ are respectively connected to two input terminals (input ports) of a 2 × 1 optical fiber coupler 234. 2 × 1 optical fiber c _Z tip collimator optical fiber with F _Z fitted with collimator to the output terminal (output port) of the optical fiber coupler 234 is connected.

According to the reference light transmission means configured as shown in FIG. 26, the reference light emitted from the other output terminal (output port) from the optical fiber coupler 220 is output by the optical fiber coupler 232 to two output terminals (output ports). Is divided into two. Reference light from these one of the output terminals (output ports) through the short optical fiber e ₁ incident on the input terminal of the optical fiber coupler 234 (input port). On the other hand, the reference light from the other output terminal (output port) of the optical fiber coupler 232 enters the input terminal (input port) of the optical fiber coupler 234 through the optical fiber e ₂ constituting the bypass optical path. In the optical fiber coupler 234, the reference light from the optical fiber e ₁ and the optical fiber e ₂ is multiplexed, is irradiated from the tip of the collimator optical fiber with F _Z to the reference mirror 240.

If the type of the optical path of the reference light by the reference light transmission means having the configuration shown in FIG. 25 or FIG. 26 as described above is optical paths A to D, the relationship between these optical paths A to D and the path of the reference light at that time is The light interference between the measurement light and the reference light when the reference light passes through the optical paths A to D is the same as that shown in FIG. That is, also in the temperature measurement system having the configuration shown in FIG. 25 or FIG. 26, the deviation amount of the interference between the measurement light and the reference light when passing through each of the optical paths A to D is the optical path length of the detour optical path of the reference light ( For example, adjustment is possible by adjusting the optical path length of the optical paths A to D by adjusting the optical fiber e or the length of the optical fibers e ₁ and e ₂ .

Therefore, by adjusting the optical path length of the detour optical path of the reference light (for example, the length of the optical fiber e or the optical fibers e ₁ and e ₂ ), the reference light passing through the optical path (for example, the optical path A) that does not pass through the detour optical path Between the interference waveform of the measurement light and the reference light that passes through the optical path that passes through the detour optical path (for example, the optical path B) and the interference waveform of the measurement light at least once, the reference light and the measurement light that pass through one of the optical paths (for example, the optical path B) The reference interference waveform selected from the interference waveform (for example, y _a0 ), the reference light passing through the other optical path (for example, optical path A), and the selected interference waveform selected from the interference waveform of the measurement light (for example, ya ₂ ) are close to each other. Can be measured in For this reason, it is sufficient to move the reference mirror 240 at least within a range in which these interference waveforms can be measured. Thereby, since the moving distance of the reference mirror 240 can be shortened, the time required for measuring the temperature of the wafer Tw can also be shortened.

(Temperature measuring device according to the fifth embodiment)
Next, a temperature measuring apparatus according to a fifth embodiment will be described with reference to the drawings. In the first to fourth embodiments described above, the measurement light reflected from the measurement target T when the measurement light is irradiated from one side of the measurement target T is configured to be received from the same side. In the fifth embodiment, the measurement light transmitted through the measurement target T when the measurement light is irradiated from one side of the measurement target T is received from the other side of the measurement target T.

  FIG. 27 shows a schematic configuration of such a temperature measuring apparatus according to the fifth embodiment. As shown in FIG. 27, the temperature measurement apparatus 200 includes a light source splitter 510 that splits (demultiplexes) the light from the light source 110 into measurement light that irradiates one side of the measurement target T and reference light, and the light source. The reference light from the splitter 510 is relayed to the reference light reflecting means 140 and the reference light reflected from the reference light reflecting means 140 is relayed to the light receiving means 150 side, the reference light from the relay splitter 520 and the measurement object And a light receiving splitter 530 for outputting the combined measurement light transmitted through the object T to the light receiving means.

(Operation of Temperature Measuring Device According to Fifth Embodiment)
In the temperature measuring apparatus 200 having such a configuration, as shown in FIG. 1, light from the light source 110 is incident on an input terminal (input port) of the light source splitter 510 via, for example, an optical fiber a, and the light source splitter 510 Is divided into two output terminals (output ports). Among these, the light from one output terminal (output port) is used as measurement light, and the measurement target T is transmitted through irradiation measurement light transmission means, for example, a collimator-equipped optical fiber F _b1 having a collimator attached to the tip of the optical fiber b ₁ . Irradiated to one side. In the present embodiment, when the measurement light is irradiated onto the measurement target T in this way, the measurement light transmitted through the measurement target T and exits to the other side as shown in FIG. To do.

On the other hand, light from the other output terminal (output port) divided by the light source splitter 510 is used as reference light, for example, one of two input terminals (input ports) of the relay splitter 520 via the optical fiber c1. And output from the output terminal (output port) of the relay splitter 520. Reference light from the relay splitter 520, is emitted from the reference light transmitting means such as an optical fiber c _Z distal optical fiber with collimator F attaching the collimator to _Z of, it is reflected by the reference light reflecting means (e.g., a reference mirror) 140.

Then, the measurement light transmitted through the measurement object T is received via a collimator-equipped optical fiber F _{b2 in} which a collimator is attached to the tip of the received light measurement light transmission means, for example, the optical fiber _b2 , and two input terminals to the light reception splitter 530. while make incidence to one of the (input port), the reference beam reflecting means (e.g., a reference mirror) the other input terminal of the reference light reflected by the 140 even through the optical fiber F _Z with collimator light splitter 530 (input port) Is incident on. The measurement light and the reference light are combined by a light receiving splitter 530 and emitted from an output terminal (output port). For example, the light and the reference light 150 are constituted by a PD using a Si photodiode, an InGaAs photodiode, a Ge photodiode, or the like. For example, the light enters through the optical fiber d, and the light receiving means 150 detects the interference waveform between the measurement light and the reference light.

(Types of measuring light by the temperature measuring device according to the fifth embodiment)
In such a temperature measurement apparatus 500, main types of measurement light that passes through the measurement target T when the measurement target T is irradiated with the measurement light from the light source 110 will be described with reference to the drawings. FIG. 28 is a conceptual diagram for explaining the types of measurement light, and the arrows shown in FIG. 28 indicate the measurement light transmitted from the measurement object T. FIG. In FIG. 28, the measurement light reflection position is shifted so that the number of round-trip reflections between the both end faces of the measurement object T in the measurement light is easy to understand. The reflection angle also changes according to the irradiation angle. For example, if the measurement light is irradiated so as to be almost perpendicular to the measurement target T, the reflection positions at the end faces S ₁ and S ₂ also substantially overlap the optical axis of the measurement light.

As the measurement light reflected from the measurement object T, as shown in FIG. 28A, both end surfaces of the measurement object T (the surface of the wafer Tw are formed without being reciprocally reflected in the measurement object T). Measurement light that passes through the first surface S ₁ and the second surface S ₂ that constitutes the back surface of the wafer Tw and passes through the measurement object T only in the forward direction (reciprocates 0.5 times) 0.5 times the reciprocating reflection measurement light) and transmitted through the first surface S ₁ of the measurement target T as shown in FIG. 28 (b), further first surface S ₁ after being reflected once at the second surface S ₂ Measurement light that is reflected once at the measurement surface, that is, measurement light that is reflected back and forth 1.5 times at both end faces S ₁ and S ₂ of the measurement object T (second surface one-time reflection measurement light or 1.5-time round-trip reflection measurement light). There is.

Others, for example, passes through the first surface S ₁ of the measurement target T as shown in FIG. 28 (c), measuring light reflected twice respectively the second surface S ₂ and the first surface S _1, i.e. the measurement As shown in FIG. 28 (d), the measurement light (second surface two-time reflection measurement light or 2.5-time round-trip reflection measurement light) reflected back and forth 2.5 times at both end faces S ₁ and S ₂ of the object T. after passing through the first surface S ₁ of the measurement target object T, the measurement light reflected three times respectively at the second surface S ₂ and the first surface S _1, i.e. at both end faces S _1, S ₂ of the measurement target T Reflected multiple times on each surface S ₁ , S ₂ of the measurement object T, such as measurement light that reflects 3.5 times (second surface 3 times reflection measurement light or 3.5 times round reflection measurement light). Accordingly, there is also measurement light that reciprocates a plurality of times within the measurement target T (second surface multiple reflection measurement light or multiple reciprocation reflection measurement light). Therefore, the light receiving means 150 can measure the interference waveforms of these measurement light and reference light.

(Specific example of interference waveform between measurement light and reference light)
Here, a specific example of light interference between the measurement light and the reference light obtained by the temperature measurement device 500 is shown in FIG. FIG. 29 shows an interference waveform between each measurement light as shown in FIG. 28 that passes through the measurement target T and the reference light reflected by the reference light reflecting means 140. In FIG. 29, the vertical axis represents the interference intensity, and the vertical axis represents the moving distance of the reference mirror. Further, as the light source 110, a low coherence light source capable of transmitting and reflecting the wafer Tw as the measurement target T is used.

According to FIG. 29, when the reference light reflecting means (for example, a reference mirror) 140 is scanned in one direction, first, both-end-surface transmission measurement light (0.5 round-trip reflection measurement light) as shown in FIG. ) And reference light interference waveform y _a0 , and then the second surface 1-time reflected measurement light (1.5 times round-trip reflected measurement light) and reference light interference waveform ya _{1 as shown in FIG.} Appears. When the reference light reflecting means 140 is further scanned, an interference waveform _ya2 between the second surface twice reflected measurement light (2.5 times round-trip reflected measurement light) and the reference light as shown in FIG. Next, an interference waveform _ya3 between the second surface three-time reflected measurement light (3.5 times round-trip reflection measurement light) and the reference light appears as shown in FIG. Thereafter, if the reference light reflecting means 140 is further scanned, the second surface 4 times reflection measurement light (4.5 times reciprocation reflection measurement light) and the second surface 5 times reflection measurement light (5.5 times) although not shown. Thus, the interference waveform of each measurement light appears continuously at equal intervals.

Each interference waveform y _a0 ~y in the interference of light of the measurement light and the reference light as shown in FIG. 29 _a3, each interference waveform y _a0 ~ in the interference light between the reference light and the measurement light as shown in FIG. 6 This is the same as the relationship with _ya3 . Accordingly, even in the interference between the measurement light and the reference light as shown in FIG. 29, the standard interference waveform and the selective interference waveform for obtaining the optical path length L of the measurement target T are represented by the standard interference waveform and the selective interference waveform. By selecting such that the peak-to-peak width is as long as possible, it is possible to improve the measurement accuracy of the peak-to-peak width between the reference interference waveform and the selected interference waveform.

For example, the interference waveform y _a0 shown in FIG. 29 is set as the reference interference waveform and the interference waveform _ya2 is set as the selected interference waveform, whereby the interference waveform _ya0 is set as the reference interference waveform and the interference waveform _ya1 is set as the selected interference waveform. Compared to the case, since the peak-to-peak width between the reference interference waveform and the selected interference waveform becomes longer, the measurement accuracy can be improved. Since the optical path length L of the measurement object T, for example, the wafer Tw, can be obtained based on the peak-to-peak width between the reference interference waveform and the selected interference waveform obtained in this way, it is converted into temperature by the same method as described above. Can do.

  For each interference waveform shown in FIG. 29 as well, by selecting the selected interference waveform based on the index K of the degree of collapse of the interference waveform as described above, the degree of collapse of the interference waveform is measured by measuring the peak-to-peak width of the interference waveform. It is possible to easily select an interference waveform that can take a longer width between the reference interference waveform and the selected interference waveform within a range in which the accuracy is not lowered.

(Temperature Measurement System According to Sixth Embodiment)
Next, a temperature measurement system for a substrate processing apparatus according to a sixth embodiment will be described with reference to the drawings. The temperature measurement system for a substrate processing apparatus according to the sixth embodiment is a specific example when the temperature measurement apparatus according to the fifth embodiment is applied to a substrate processing apparatus. FIG. 30 is a diagram illustrating a schematic configuration of a temperature measurement system according to the sixth embodiment. Here, as an example of the temperature measurement target T in a substrate processing apparatus such as a plasma etching apparatus, a case where it is applied to the temperature measurement of the wafer Tw will be described as an example.

  The temperature measurement system shown in FIG. 30 is roughly composed of a temperature measurement device 600, a substrate processing device 300, and a control device 400. In the temperature measuring apparatus 600 shown in FIG. 30, the light source 110 shown in FIG. 27 is configured by a low coherence light source, for example, an SLD 210 that emits light having low coherence, and the light receiving means 150 is configured by a PD 250 using, for example, a Ge photodiode. The reference light reflecting means 140 is composed of, for example, a reference mirror 240, the driving means 142 is composed of, for example, a stepping motor 242 that drives the reference mirror 240, and the light source splitter 510, the relay splitter 520, and the light receiving splitter 530 are each set to, for example, 1 A × 2 optical fiber coupler 610, a 2 × 1 optical fiber coupler 620, and a 1 × 2 optical fiber coupler 630 are configured.

The configurations of the substrate processing apparatus 300 and the control apparatus 400 shown in FIG. 30 are almost the same as those shown in FIG. 5, but the substrate processing apparatus 300 shown in FIG. 5 reflects and reflects the measurement light on the back side of the wafer Tw. whereas arranging the collimator optical fiber with F for receiving light on the lower electrode 340 is irradiated with measurement light to the first surface S ₁ which constitutes a surface of a substrate processing apparatus 300, wafer Tw shown in FIG. 30 the collimator optical fiber with F _b1 while disposed in the upper electrode 350 for the lower electrode 340 of the collimator optical fiber with F _b2 for receiving the measurement light from the second surface S ₂ which constitutes the rear surface of the wafer Tw It differs in the point arrange | positioned.

Specifically, the collimator-equipped optical fiber _Fb1 is arranged so that the measurement light can be irradiated toward the wafer Tw through a through-hole 358 formed in, for example, the center of the electrode support 352 of the upper electrode 350. , optical fiber F _b2 with collimator through the through-hole 344 formed in the example central portion of the lower electrode 340 are arranged to allow receiving the measurement light from the wafer Tw. The position in the in-plane direction of the wafer Tw on which the collimator-equipped optical fibers F _b1 and F _b2 are disposed is the measurement light irradiated from the collimator-equipped optical fiber F _b1 via the wafer Tw. If it is a position where light can be received at _b2 , it may not be the central portion of the wafer Tw as shown in FIG. For example, the collimator-equipped optical fibers F _b1 and F _b2 may be disposed so that the measurement light is irradiated to the end of the wafer Tw.

  According to the temperature measurement system shown in FIG. 30 configured as described above, the control device 400 moves the reference mirror 240 in one direction, thereby obtaining the same light interference between the measurement light and the reference light as in FIG. Can do. Therefore, even by the temperature measurement system as shown in FIG. 30, by selecting the reference interference waveform and the selected interference waveform from the plurality of interference waveforms measured by the PD 250 so that the peak-to-peak width is as long as possible, Since the measurement accuracy of the peak-to-peak width between the interference waveform and the selected interference waveform can be improved, the temperature measurement accuracy of the wafer Tw can be improved.

  Also in the temperature measurement system according to the present embodiment, by selecting the selected interference waveform based on the index K of the degree of collapse of the interference waveform as described above, the degree of collapse of the interference waveform can be reduced to the peak-to-peak width of the interference waveform. It is possible to easily select an interference waveform that can take a longer width between the reference interference waveform and the selected interference waveform within a range that does not reduce the measurement accuracy.

(Temperature measurement system that does not use optical fiber)
Note that the temperature measurement system shown in the second to sixth embodiments described above uses an optical fiber as the measurement light transmission means and the reference light transmission means, and transmits light such as measurement light and reference light used in the temperature measurement to the optical fiber. However, the present invention is not necessarily limited to this, and the principle as shown in FIG. 31 is used without using optical fiber or collimated fiber for measuring light or reference light used in temperature measurement. The air may be transmitted based on the above.

  FIG. 31 shows the principle of a temperature measuring apparatus 700 that transmits light using the air without using an optical fiber or a collimating fiber. In such a temperature measuring device 700, light from a light source (for example, SLD) 110 is transmitted through the air and applied to a splitter (for example, half mirror) 710, and is divided into reference light and measurement light by the splitter 710. It is done. The measurement light is transmitted through the air and irradiated to the measurement target T arranged opposite to the measurement light, and is reflected by the front and back surfaces of the measurement target T. On the other hand, the reference light is transmitted through the air and irradiated onto the reference light reflecting means (for example, the reference mirror) 140, and is reflected by the mirror surface of the reference light reflecting means. Then, the reflected measurement light and reference light are transmitted through the air, enter the splitter 710 again, and are received by the light receiving means 150. At that time, depending on the optical path length of the reference light, they overlap and cause interference, and the interference wave is detected by the light receiving means 150. By using such a principle, light can be transmitted without using an optical fiber or a collimating fiber. As a result, even light having a wavelength that does not pass through the optical fiber or collimate fiber (for example, a wavelength of 2.5 μm or more) can be used as the light source 110 for measurement light or reference light.

(Control system for substrate processing equipment)
In the temperature measurement system shown in the second to sixth embodiments described above, the electrode plate of the upper electrode 350 is provided by providing, for example, an electrode plate 351 of the upper electrode 350 or a controller for controlling the temperature of the wafer Tw as the various controllers 470. It is also possible to configure the control system of the substrate processing apparatus that controls the temperature of the 351 and the wafer Tw by various controllers 470 according to the measurement result while measuring the temperature by the temperature measuring apparatus.

  In this case, the various controllers 470 may include, for example, an inner refrigerant controller and an outer refrigerant controller as those for controlling the temperature of the electrode plate 351 of the upper electrode 350. The inner refrigerant controller controls the temperature of the inner part of the upper electrode 350 by controlling the temperature and flow rate of the refrigerant circulated to the inner refrigerant flow path 354. The outer refrigerant controller controls the temperature of the outer portion of the upper electrode 350 by controlling the temperature and flow rate of the refrigerant circulated to the outer refrigerant flow path 353.

  Furthermore, the various controllers 470 may include, for example, an ESC (electrostatic chuck) system controller and an FR (focus ring) system controller as a controller for controlling the temperature of the wafer Tw. The ESC system controller applies a voltage applied to an electrostatic chuck (ESC) (not shown) for electrostatically attracting the wafer to the lower electrode 340, the gas flow rate of the backside gas supplied to the wafer Tw via the electrostatic chuck, and the gas The pressure and the temperature of the refrigerant to be circulated through the refrigerant flow path formed in the lower electrode 340 are controlled. Further, the FR system controller includes a voltage applied to a peripheral ring (not shown) provided to surround the periphery of the wafer, for example, a focus ring, a gas flow rate and a gas pressure of a backside gas supplied to the wafer Tw via the focus ring, and the like. Is to control.

  Thus, by configuring the temperature measurement system shown in the second to sixth embodiments as a control system for the substrate processing apparatus, the temperature of the upper electrode 350 or the temperature of the wafer Tw can be controlled. The process characteristics of the wafer Tw can be accurately controlled, and the stability of the substrate processing apparatus can be improved.

(Thickness measuring device and thickness measuring system)
In the first to sixth embodiments, the case of measuring the temperature of the measurement object has been described. However, the present invention is not necessarily limited to this, and is applied to the case of measuring the thickness of the measurement object. May be. That is, in the first to fifth embodiments, for example, when the measurement target T is irradiated, the width between peaks of the interference waveform between the measurement light transmitted or reflected from the measurement target and the reference light is the optical path of the measurement target. By utilizing the fact that it corresponds to the length, the inter-peak width of the interference waveform is measured as the moving distance of the reference light reflecting means (for example, the reference mirror) to obtain the optical path length of the measurement object. The case of converting to temperature has been described.

  However, since this optical path length L is expressed by thickness d × refractive index n and refractive index n depends on temperature, if the refractive index n at the temperature when the optical path length L is measured is known, the measured optical path length L Is divided by the refractive index n to obtain the thickness d of the object to be measured. Therefore, for example, the relationship between the temperature of the measurement object and the refractive index n is previously stored in the memory 440 of the control device 400 as thickness reference conversion data, and the temperature when the optical path length L of the measurement object is measured is calculated. Measured by another temperature measuring means (for example, resistance thermometer, fluorescent thermometer, etc.), the refractive index n at that temperature is obtained from the reference conversion data for thickness, and the optical path length L is divided by this refractive index n. By doing so, the thickness d of the measurement object can be obtained.

  Thus, since the thickness of the measurement object can be obtained using the interference waveform between the measurement light and the reference light, the temperature measurement device according to the first to fifth embodiments can be obtained by using this principle. The temperature measuring system of the substrate processing apparatus can also be configured as a thickness measuring apparatus and a thickness measuring system of the substrate processing apparatus, respectively. By using such a thickness measuring apparatus and a thickness measuring system for a substrate processing apparatus, for example, the thickness of a consumable part is periodically measured by using, for example, the electrode plate 351 of the upper electrode 350 of the substrate processing apparatus 300 as a measurement target T. Thus, the amount of consumption of consumable parts such as the electrode plate 351 can be measured. Accordingly, it is possible to predict the replacement time of the electrode plate 351 and the like.

  The thickness is measured when the substrate processing apparatus 300 is in the same temperature state, such as when the power is turned on or after maintenance, and the refractive index n at that temperature is stored in the memory 440 of the control apparatus 400 or the like. If it is memorized, it is not necessary to measure the temperature of the object to be measured each time the thickness is measured, so there is no need for another temperature measuring means, and the time and labor for measuring the thickness are also eliminated. It can be reduced as much as possible. In addition, by causing the control device 400 to function as a thickness calculating unit or a control unit, the thickness of the measurement target T can be obtained based on the result of interference measurement between the measurement light and the reference light by the control device 400. it can.

(Light intensity of light source)
The temperature measuring apparatus in the first to sixth embodiments further includes a light intensity adjusting unit that can adjust the light intensity of the light source, for example, the SLD 210, and the controller 400 adjusts the light intensity via, for example, the light intensity controllers provided in various controllers. The light intensity of the light source 110 may be changed during measurement of light interference between the measurement light and the reference light by controlling the means.

  In this way, during measurement of the interference between the measurement light and the reference light, the measurement light is prevented from being reduced in light intensity due to being transmitted through the measurement object T and reflected multiple times. It is possible to prevent a decrease in the S / N ratio of the interference waveform between the measurement light and the reference light so that the interference waveform does not collapse. Thereby, for example, since the detection accuracy of the peak position of the interference waveform can be improved, the measurement accuracy of temperature and thickness based on the peak-to-peak width of the interference waveform can be improved.

As a more specific light intensity adjustment method of the light source, for example, during the measurement of the light interference between the measurement light and the reference light, the light intensity of the light source is adjusted according to the moving distance of the reference light reflecting means (for example, the reference mirror) 140. Increasing gradually. According to this, since the light intensity can be increased as the measurement light having a larger number of round-trip reflections at the both end faces S ₁ and S ₂ of the measurement target T, the interference waveform between the measurement light and the reference light can be increased. A decrease in the S / N ratio can be prevented.

Further, during the measurement of the light interference between the measurement light and the reference light, the light intensity of the light source may be changed in accordance with the number of round-trip reflections at both end faces S ₁ and S ₂ of the measurement object T of the measurement light. Good. Since the light intensity of the measurement light decreases as the number of round-trip reflections at both end faces S ₁ and S ₂ of the measurement object T of the measurement light increases, for example, at both end faces S ₁ and S ₂ of the measurement object T of the measurement light By increasing the light intensity of the light source as the number of reciprocal reflections increases, the light intensity of the measurement light can be accurately prevented from decreasing. Therefore, the S / N of the interference waveform between such measurement light and the reference light can be prevented. A decrease in the ratio can also be prevented accurately.

  In addition, the reflection intensity of the measurement light from the measurement object T is measured in advance, and when measuring the interference between the measurement light of the measurement object T and the reference light, the reflection intensity of the measurement light measured in advance ( For example, by changing the light intensity of the light source in accordance with the interference intensity of the interference waveform between the measurement light and the reference light), the light intensity of the light source can be increased as the measurement light reflection intensity decreases. A decrease in the S / N ratio of the interference waveform with the reference light can be accurately prevented.

  As described above, by adjusting the light intensity of the light source, it is possible to prevent a decrease in the S / N ratio of the interference waveform between the measurement light and the reference light. Decline can be prevented. As a result, an interference waveform having a longer peak-to-peak width between the reference interference waveform and the selected interference waveform can be selected as the selected interference waveform, and the temperature measurement accuracy can be further improved.

  In addition, based on the index K of the degree of collapse of the interference waveform between the measurement light and the reference light as described above, the interference waveform is selected such that an interference waveform in a range where the index K does not exceed a predetermined value is selected as the selected interference waveform. You may make it combine the method of adjusting the light intensity of the said light source with the method. According to this, an interference waveform with an improved S / N ratio of the interference waveform can be received by adjusting the light intensity of the light source during measurement of the interference between the measurement light and the reference light. Thus, the index K of the degree of collapse of the interference waveform is also improved. Therefore, by adjusting the light intensity of the light source, it is possible to increase the interference waveform in a range where the index K of the degree of collapse of the interference waveform does not exceed a predetermined value. This makes it possible to easily select an interference waveform in which the peak-to-peak width between the reference interference waveform and the selected interference waveform is longer and the collapse of the interference waveform is minimized as the selected interference waveform. For this reason, the temperature measurement accuracy can be further improved.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, the wafer Tw to be processed in the processing chamber 310 of the substrate processing apparatus 300 is described as an example of the substrate to be measured as the measurement target. The substrate to be processed may be a liquid crystal substrate such as a glass substrate. In addition, for example, an electrode plate (for example, an electrode plate for the lower electrode 340 or the upper electrode 350) disposed in the processing chamber 310 of the substrate processing apparatus 300, a peripheral ring (for example, a focus ring) disposed around the wafer, or the like. As described above, the temperature or thickness can be measured using various components and components in the substrate processing apparatus as the measurement object T.

  In the above-described embodiment, the case where one measurement target T such as the wafer Tw is a measurement target has been described. However, the present invention is not necessarily limited to this. A plurality of measurement points in one object such as the wafer Tw may be measured.

  In this case, the measurement light from the light source may be further demultiplexed and applied to each measurement object T or each measurement point. As a result, since the interference waveform between the measurement light and the reference light of each measurement object or each measurement point can be measured at one time, these temperatures or thicknesses can also be measured at one time, and each measurement object or each measurement point can be measured. The time for measuring the temperature or thickness of the film can be greatly shortened.

  In addition, by irradiating a plurality of measurement objects arranged to face each other with measurement light, light transmitted through the measurement object arranged first is used as measurement light for the next measurement object, The measurement light reflected from each measurement object may be received by the light receiving means. According to this, since the temperature or thickness of a plurality of measurement objects can be measured at one time with one measurement light, the measurement time of temperature or thickness can be shortened, and the measurement light transmission means, for example, The handling of the optical fiber is facilitated, and the time required for attaching the temperature measuring apparatus to, for example, a substrate processing apparatus can be reduced.

  Further, the measurement target in the present invention may be a measurement target layer constituting a part of an object such as an inner layer of the wafer Tw in addition to the measurement target T as an object such as the wafer Tw. Good.

  In the above-described embodiment, the case where the substrate processing apparatus is applied to, for example, a plasma processing apparatus has been described. However, the present invention is not necessarily limited to this, and film reforming such as a film forming apparatus or a heat treatment apparatus that does not use plasma. The temperature / thickness measuring apparatus according to the present invention is not limited to the substrate processing apparatus and can be applied to various other processing apparatuses.

  The present invention can be applied to, for example, a temperature / thickness measuring apparatus, a temperature measuring method, and a temperature / thickness measuring system for measuring the temperature of a semiconductor wafer, a liquid crystal substrate, etc., and a control system and control for controlling a substrate processing apparatus Applicable to the method.

It is a block diagram showing a schematic structure of a temperature measuring device concerning a 1st embodiment of the present invention. It is an idea figure for demonstrating the kind of measurement light received when irradiating measurement light to a measuring object in the embodiment. It is a figure which shows the specific example of the interference wave of the light of the measurement light and reference light which are obtained by the temperature measuring device concerning the embodiment, The figure (a) is the light before the temperature of each temperature measurement object changes FIG. 2B shows an example of the interference wave of light after the temperature of each temperature measurement object has changed. It is an experimental result which shows the specific example of the relationship between the temperature of a measuring object, and optical path length. It is a block diagram which shows schematic structure about the specific example of the temperature measurement system of the substrate processing apparatus concerning 2nd Embodiment of this invention. It is a figure which shows the specific example of the interference wave of the light of the measurement light and reference light which are obtained with the temperature measuring device concerning the embodiment. It is a figure which shows the experimental result which performed the temperature measurement using the interference waveform shown in FIG. 6, and computed the temperature measurement error. It is a figure which shows the specific example of the actual measurement waveform which expanded and showed one interference waveform, and the processing waveform which performed predetermined processing with respect to this actual measurement waveform. It is a diagram illustrating a processing waveform yb0 for interference waveform _{y a0} shown in Fig. It is a diagram illustrating a processing waveform yb1 of interference waveforms _{y a1} shown in FIG. It is a diagram illustrating a processing waveform yb2 for interference waveform _{y a2} shown in FIG. It is a diagram illustrating a processing waveform yb3 for interference waveform _{y a3} shown in FIG. Is a diagram showing an envelope yd0 for interference waveform _{y a0} shown in Fig. Is a diagram showing an envelope yd1 for interference waveform _{y a1} shown in FIG. Is a diagram showing an envelope yd2 for interference waveform _{y a2} shown in FIG. Is a diagram showing an envelope yd3 for interference waveform _{y a3} shown in FIG. It is a diagram illustrating a result of obtaining an index K of degree collapse the envelope _y d0 _{~y d3} of each of the interference waveform _y a0 _{~y a3} shown in FIGS. 13 to 16. It is a block diagram which shows schematic structure about the specific example of the temperature measurement system of the substrate processing apparatus concerning 3rd Embodiment of this invention. It is a figure which shows the kind of optical path of the measurement light by the temperature measuring device concerning the embodiment. It is a figure which shows the specific example of the interference wave of the light of the measurement light and reference light which are obtained with the temperature measuring device concerning the embodiment. It is a block diagram which shows schematic structure about the modification of the temperature measurement system of the substrate processing apparatus concerning the embodiment. It is a block diagram which shows schematic structure about the specific example of the temperature measurement system of the substrate processing apparatus concerning 4th Embodiment of this invention. It is a figure which shows the specific example of the interference wave of the light of the measurement light and reference light which are obtained with the temperature measuring device concerning the embodiment. It is a block diagram which shows schematic structure about the modification of the temperature measurement system of the substrate processing apparatus concerning the embodiment. It is a block diagram which shows schematic structure about the other modification of the temperature measurement system of the substrate processing apparatus concerning the embodiment. It is a block diagram which shows schematic structure about the other modification of the temperature measurement system of the substrate processing apparatus concerning the embodiment. It is a block diagram which shows schematic structure about the temperature measurement apparatus of the substrate processing apparatus concerning 5th Embodiment of this invention. It is an idea figure for demonstrating the kind of measurement light received when irradiating measurement light to a measuring object in the embodiment. It is a figure which shows the specific example of the interference wave of the light of the measurement light and reference light which are obtained with the temperature measuring device concerning the embodiment. It is a block diagram which shows schematic structure about the temperature measurement system of the substrate processing apparatus concerning 6th Embodiment of this invention. It is a figure for demonstrating the principle of the temperature measuring apparatus which transmits light, such as measurement light and reference light, using the air. It is a figure for demonstrating the principle of the conventional temperature measuring apparatus. It is the figure which showed notionally the interference waveform measured by the temperature measuring apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Temperature measuring device 110 Light source 120 Splitter 140 Reference light reflection means 142 Driving means 150 Light receiving means 200 Temperature measuring device 210 SLD
220 Optical fiber coupler (splitter)
222 Optical fiber coupler (reference beam splitter)
230 Optical fiber coupler (diverter optical path connection splitter)
232 Optical fiber coupler (diverter optical path splitter)
234 Optical fiber coupler (diverter optical path splitter)
240 Reference mirror 242 Motor 244 Reference mirror 246 Reference mirror 250 PD
300 Substrate processing apparatus 310 Processing chamber 320 High-frequency power source 330 High-frequency power source 340 Lower electrode 342 Refrigerant channel 344 Through hole 350 Upper electrode 351 Electrode plate 352 Electrode support 353 Outer refrigerant channel 354 Inner refrigerant channel 356 Low heat transfer layer 358 Through hole 400 Controller 410 CPU
420 Motor driver 430 Motor controller 440 Memory 450 Buffer 460 A / D converter 470 Various controllers 500 Temperature measuring device 510 Light source splitter 520 Relay splitter 530 Light receiving splitter 600 Temperature measuring device 610 Optical fiber coupler (light source splitter)
620 Optical fiber coupler (relay splitter)
630 Optical fiber coupler (light receiving splitter)
700 Temperature Measuring Device 710 Splitter T Measurement Object Tw Wafer

Claims (35)

A light source that irradiates and reflects light that is transmitted through and reflected from both end faces of the measurement object and that can be reflected back and forth at least twice at both end faces of the measurement object;
A splitter for splitting light from the light source into measurement light and reference light;
Reference light reflecting means for reflecting reference light from the splitter;
An optical path length changing means for changing an optical path length of the reference light reflected from the reference light reflecting means;
Reference light transmission means for transmitting the reference light from the splitter to a reference light irradiation position for irradiating the reference light to the reference light reflection means;
Measurement light transmission means for transmitting the measurement light from the splitter to the measurement light irradiation position for irradiating the measurement object toward the measurement object;
A light receiving means for measuring an interference waveform of a plurality of measurement lights obtained by interference between the measurement light transmitted or reflected by the measurement object and the reference light reflected from the reference light reflection means;
Interference of measurement light that reciprocally reflects at least two times at both end faces of the measurement object with respect to the measurement light of the reference interference waveform, with reference to a certain interference waveform among the interference waveforms of the measurement light measured by the light receiving means. Using the waveform as a selective interference waveform, the optical path length of the measurement light between both end faces of the measurement object is measured based on the reference interference waveform and the selective interference waveform, and the temperature or thickness of the measurement object is measured based on the optical path length. Measuring means for measuring the thickness;
A temperature / thickness measuring apparatus comprising: 2. The temperature / thickness measuring apparatus according to claim 1, wherein the measuring unit selects a selected interference waveform based on a degree of collapse of the interference waveform of the measurement light received by the light receiving unit. The degree of collapse of the interference waveform includes an approximate curve obtained by curve approximation of the entire wave train constituting the interference waveform, and an approximate curve obtained by curve approximation of the interference waveform based on the individual repetitive waveforms constituting the wave series of the interference waveform. The temperature / thickness measuring apparatus according to claim 2, wherein the temperature / thickness measuring apparatus is a deviation amount. The reference approximate curve of the entire wave series constituting the interference waveform is a normal distribution curve, and the approximate curve based on the individual repetitive waveforms constituting the wave series of the interference waveform is an envelope obtained based on each repetitive waveform. The temperature / thickness measurement apparatus according to claim 3, wherein the temperature / thickness measurement apparatus is provided. 2. The temperature / thickness measuring apparatus according to claim 1, wherein the measuring light transmission means includes a bypass optical path connected in parallel with the measuring light optical path in the middle of the measuring light optical path. 6. The temperature according to claim 5, wherein an optical path length of a bypass optical path of the measurement light is adjusted so that a reference interference waveform and a selective interference waveform of the measurement light are respectively measured in the vicinity in the light receiving unit. / Thickness measuring device. The reference light reflecting means is provided with a plurality of reflecting surfaces, and the reference light from the splitter is reflected by the reflecting surfaces so that a plurality of reference lights having different optical path lengths can be reflected. Item 2. The temperature / thickness measuring apparatus according to Item 1. 8. The position of a plurality of reflecting surfaces of the reference light reflecting means is adjusted so that a reference interference waveform and a selective interference waveform of the measuring light are respectively measured in the vicinity in the light receiving means. The temperature / thickness measuring apparatus as described. A reference light splitter for further splitting the reference light from the splitter into a plurality of reference lights is provided, and the reference light reflecting means is irradiated with the plurality of reference lights from the reference light splitter with different optical path lengths. The temperature / thickness measuring apparatus according to claim 1. 10. The optical path lengths of a plurality of reference lights from the reference light splitter are adjusted so that a reference interference waveform and a selective interference waveform of the measurement light are respectively measured in the vicinity in the light receiving means. The temperature / thickness measuring apparatus according to 1. 2. The temperature / thickness measuring apparatus according to claim 1, wherein the reference light transmission means includes a bypass optical path connected in parallel to the optical path of the reference light in the middle of the optical path of the reference light. 12. The temperature according to claim 11, wherein the optical path length of the detour optical path of the reference light is adjusted so that the reference interference waveform and the selective interference waveform of the measurement light are respectively measured in the vicinity in the light receiving means. / Thickness measuring device. The measurement light transmission means is arranged on one side of the measurement object, transmits the measurement light from the light source, irradiates the measurement object on one end surface, and reciprocates on both end surfaces of the measurement object. 2. The temperature / thickness measurement according to claim 1, wherein the measurement light that is reflected or reflected by one end face without reciprocating and received and transmitted is transmitted to the light receiving means. apparatus. The measurement light transmission means is disposed on one side of the measurement object, transmits the measurement light from the light source, and irradiates the measurement light on one end surface of the measurement object; and It is arranged on the other side, reciprocally reflects at both end faces of the measurement object, transmits through one end face without reciprocating, and receives measurement light that passes through the other end face, toward the light receiving means 2. The temperature / thickness measuring apparatus according to claim 1, wherein a light receiving / transmitting means for transmitting is provided separately. The temperature / thickness measuring apparatus according to claim 1, wherein each of the lights is transmitted through the air. The measurement object is formed of silicon or silicon oxide film,
The temperature / thickness measuring apparatus according to claim 1, wherein the light source is capable of emitting light having a wavelength of 1.0 to 2.5 μm. The measurement object is a substrate to be processed in a substrate processing apparatus or an electrode plate disposed in the substrate processing apparatus so as to face the substrate to be processed. Temperature / thickness measuring device. Irradiating measurement light split from a light source that irradiates light that is transmitted through and reflected from both end faces of the measurement target toward the measurement target, and irradiating reference light toward reference light reflecting means;
By scanning the reference light reflecting means in one direction, while changing the optical path length of the reference light reflected from the reference light reflecting means, the measuring light that is transmitted or reflected by the measurement object and reflected from the reference light reflecting means Measuring interference waveforms of a plurality of measurement lights obtained by interference with reference light;
Interference of measurement light that reciprocally reflects at least two times at both end faces of the measurement object with respect to the measurement light of the reference interference waveform, with reference to a certain interference waveform among the interference waveforms of the measurement light measured by the light receiving means. Using the waveform as a selective interference waveform, the optical path length of the measurement light between both end faces of the measurement object is measured based on the reference interference waveform and the selective interference waveform, and the temperature or thickness of the measurement object is measured based on the optical path length. Measuring the thickness,
A temperature / thickness measuring method characterized by comprising: 19. The temperature / thickness measuring method according to claim 18, wherein the measuring unit selects the selected interference waveform based on the degree of collapse of the interference waveform of the measurement light received by the light receiving unit. The degree of collapse of the interference waveform includes an approximate curve obtained by curve approximation of the entire wave train constituting the interference waveform, and an approximate curve obtained by curve approximation of the interference waveform based on the individual repetitive waveforms constituting the wave series of the interference waveform. The temperature / thickness measurement method according to claim 18, wherein the temperature / thickness measurement method is a deviation amount from The reference approximate curve of the entire wave train constituting the interference waveform is a normal distribution curve, and the approximate curve based on each repeated waveform constituting the wave series of the interference waveform is an envelope obtained based on each repeated waveform. The temperature / thickness measuring method according to claim 20, wherein In the middle of the optical path of the measurement light, a bypass optical path connected in parallel with the optical path of the measurement light is provided,
The step of measuring the temperature or thickness includes either one of an interference waveform of the measurement light passing through the optical path not passing through the bypass optical path and an interference waveform of the measurement light passing through the optical path passing through the bypass optical path at least once. Based on the reference interference waveform selected from the interference waveform of the measurement light passing through and the selected interference waveform selected from the interference waveform of the measurement light passing through the other optical path. 19. The temperature / thickness measuring method according to claim 18, wherein the optical path length is measured. The reference light reflecting means is provided with a plurality of reflecting surfaces,
In the step of measuring the temperature or thickness, the reference light split from the light source reflects the interference between the reference light reflected from any one of the plurality of reference lights reflected from each of the reflection faces and the measurement light. Based on the reference interference waveform selected from the waveform and the selected interference waveform selected from the interference waveform of the reference light and the measurement light reflected from another reflection surface, the optical path length of the measurement light between both end faces of the measurement target The temperature / thickness measurement method according to claim 18, wherein the temperature is measured. A reference light splitter for splitting the reference light from the splitter into a plurality of reference lights having different optical path lengths;
The step of measuring the interference includes the reference interference waveform selected from the interference waveform of any one of the reference light and the measurement light among the plurality of reference lights split from the reference light splitter, another reference light, 19. The temperature / thickness measurement method according to claim 18, wherein the optical path length of the measurement light between both end faces of the measurement object is measured based on the selected interference waveform selected from the interference waveform of the measurement light. In the middle of the optical path of the reference light, a bypass optical path connected in parallel with the optical path of the reference light is provided,
The step of measuring the temperature or the thickness includes an interference waveform of the reference light and the measurement light passing through the optical path not passing through the bypass optical path, and an interference waveform of the reference light and the measurement light passing through the optical path passing through the bypass optical path at least once. , Based on the reference interference waveform selected from the interference waveform of the reference light passing through one of the optical paths and the measurement light, and the selected interference waveform selected from the interference waveform of the reference light passing through the other optical path and the measurement light 19. The temperature / thickness measuring method according to claim 18, wherein an optical path length of the measuring light between both end faces of the measuring object is measured. 26. The temperature / thickness measuring method according to claim 18, wherein each of the lights is transmitted through the air. The measurement object is formed of silicon or silicon oxide film,
27. The temperature / thickness measuring method according to claim 18, wherein the light source is capable of irradiating light having a wavelength of 1.0 to 2.5 [mu] m. 28. The measurement object according to claim 27, wherein the measurement object is a substrate to be processed in a substrate processing apparatus or an electrode plate disposed to face the substrate to be processed in the substrate processing apparatus. Temperature / thickness measurement method. 29. The temperature / thickness measuring method according to claim 18, wherein the light intensity of the light source is changed during measurement of the measurement light, the reference light, and an interference waveform. 30. The temperature / thickness measurement method according to claim 29, wherein the light intensity of the light source is gradually increased in accordance with a moving distance of the reference light reflecting means. 30. The temperature / thickness measurement method according to claim 29, wherein the light intensity of the light source is increased as the interference waveform of the measurement light has a greater number of reciprocal reflections at both end faces of the measurement target. 30. The temperature / thickness measurement method according to claim 29, wherein the reflection intensity of the measurement light received by the light receiving means is measured in advance, and the light intensity of the light source is changed according to the reflection intensity. A temperature / thickness comprising a substrate processing apparatus for performing a predetermined process on a substrate to be processed in a processing chamber, a temperature / thickness measuring apparatus attached to the substrate processing apparatus, and a control device for controlling the temperature / thickness measuring apparatus. Measuring system,
The temperature / thickness measuring apparatus emits light that is transmitted through and reflected from both end surfaces of the substrate to be measured and that can be reflected back and forth at least twice at both end surfaces of the substrate to be processed. A light source, a splitter for splitting light from the light source into measurement light and reference light, reference light reflecting means for reflecting the reference light from the splitter, and reference light reflected from the reference light reflecting means An optical path length changing means for changing the optical path length of the light source, a reference light transmitting means for transmitting the reference light from the splitter to the reference light irradiating position for irradiating the reference light to the reference light reflecting means, and a measuring light from the splitter Measurement light transmitting means for transmitting the measurement light to the processing substrate, the measurement light transmitting or reflecting the processing substrate, and the reference light reflected from the reference light reflecting means. And a light receiving means for measuring the interference waveforms of a plurality of measurement light obtained by,
The control device uses a certain interference waveform as a reference among the interference waveforms of the measurement light measured by the light receiving means of the temperature / thickness measurement device, and the both end surfaces of the substrate to be processed are more than the measurement light of the reference interference waveform. And measuring the optical path length of the measurement light between both end faces of the substrate to be processed based on the reference interference waveform and the selected interference waveform, with the interference waveform of the measurement light that reciprocally reflects at least twice as a selected interference waveform. , A temperature / thickness measuring system for measuring the temperature or thickness of the substrate to be processed based on the optical path length. A substrate processing apparatus for performing a predetermined process on a substrate to be processed in a processing chamber, a temperature / thickness measuring apparatus installed in the substrate processing apparatus, the temperature / thickness measuring apparatus, and the substrate processing apparatus are controlled. , A control system comprising a control device for controlling at least one of temperature control and process control of the substrate to be processed,
The temperature / thickness measuring apparatus emits light that is transmitted through and reflected from both end surfaces of the substrate to be measured and that can be reflected back and forth at least twice at both end surfaces of the substrate to be processed. A light source, a splitter for splitting light from the light source into measurement light and reference light, reference light reflecting means for reflecting the reference light from the splitter, and reference light reflected from the reference light reflecting means An optical path length changing means for changing the optical path length of the light source, a reference light transmitting means for transmitting the reference light from the splitter to the reference light irradiating position for irradiating the reference light to the reference light reflecting means, and a measuring light from the splitter Measurement light transmitting means for transmitting the measurement light to the processing substrate, the measurement light transmitting or reflecting the processing substrate, and the reference light reflected from the reference light reflecting means. And a light receiving means for measuring the interference waveforms of a plurality of measurement light obtained by,
The control device uses a certain interference waveform as a reference among the interference waveforms of the measurement light measured by the light receiving means of the temperature / thickness measurement device, and the both end surfaces of the substrate to be processed are more than the measurement light of the reference interference waveform. And measuring the optical path length of the measurement light between both end faces of the substrate to be processed based on the reference interference waveform and the selected interference waveform, with the interference waveform of the measurement light that reciprocally reflects at least twice as a selected interference waveform. The temperature or thickness of the substrate to be processed is measured based on the optical path length, and the temperature control and the process control of the substrate to be processed in the processing chamber of the substrate processing apparatus are based on the temperature or thickness. A control system that performs at least one control. A control method for a control system of a substrate processing apparatus for performing a predetermined process on a substrate to be processed in a processing chamber,
Irradiating measurement light split from a light source that irradiates light that is transmitted through and reflected from both end faces of the measurement target toward the measurement target, and irradiating reference light toward reference light reflecting means;
By scanning the reference light reflecting means in one direction, while changing the optical path length of the reference light reflected from the reference light reflecting means, the measuring light that is transmitted or reflected by the measurement object and reflected from the reference light reflecting means Measuring interference waveforms of a plurality of measurement lights obtained by interference with reference light;
Interference of measurement light that reciprocally reflects at least two times at both end faces of the measurement object with respect to the measurement light of the reference interference waveform, with reference to a certain interference waveform among the interference waveforms of the measurement light measured by the light receiving means. Using the waveform as a selective interference waveform, the optical path length of the measurement light between both end faces of the measurement object is measured based on the reference interference waveform and the selective interference waveform, and the temperature or thickness of the measurement object is measured based on the optical path length. Measuring the thickness,
Performing at least one of temperature control and process control of the substrate to be processed in the substrate processing apparatus based on the measured temperature or thickness of the measurement object;
A control method characterized by comprising:

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