JP2010199526A - Plasma processing apparatus, and method and apparatus for measuring temperature - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of highly accurately measuring the temperature of a substrate or the like and capable of highly accurately and efficiently performing plasma processing of the substrate, and to provide a temperature measuring method and a temperature measuring apparatus. <P>SOLUTION: The plasma processing apparatus includes a vacuum chamber 2, a mounting table 3, a base plate 9 arranged under the mounting table 3 through a space between the mounting table 3 and the base plate 9, and a temperature measuring means, wherein an upper portion over the mounting table 3 is set to be maintained under a vacuum atmosphere and the space between the mounting table 3 and the base plate 9 is set to be maintained under a normal pressure atmosphere. In the plasma processing apparatus, airtightly sealed temperature measuring windows 12 to 15 are formed between the upper and lower surfaces of the mounting table 3 so as to optically communicate the upper and lower surfaces of the mounting table 3 to transmit measured light of the temperature measuring means, and a connection member 30 for connecting the mounting table 3 and the base plate 9 is formed between the mounting table 3 and the base plate 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus, a temperature measuring method, and a temperature measuring apparatus for processing using plasma such as a substrate such as a semiconductor wafer or a substrate for a liquid crystal display device.

  Accurately measuring the temperature of a substrate processed by a plasma processing apparatus, such as a semiconductor wafer or a liquid crystal display substrate, is formed on the semiconductor wafer or liquid crystal display substrate by the results of various processes such as film formation and etching. This is also extremely important from the viewpoint of accurately controlling the shape and physical properties of the film and holes. For this reason, it has been conventionally performed to measure the temperature of a semiconductor wafer or a substrate for a liquid crystal display device by various methods such as a resistance thermometer or a measurement method using a fluorescent thermometer for measuring the temperature of the back surface of the substrate. It has been broken.

  In recent years, a temperature measurement technique using a low coherence interferometer capable of directly measuring the substrate temperature, which has been difficult with the conventional temperature measurement method as described above, is known. Furthermore, in the temperature measurement technique using the low coherence interferometer, the light from the light source is divided into the measurement light for temperature measurement and the reference light by the first splitter, and the divided measurement light is further divided by the second splitter. The measurement light is divided into n measurement lights, and the n measurement lights are irradiated onto the n measurement points. The reflected light of the n measurement lights and the reflected light of the reference light reflected by the reference light reflecting means A technique has also been proposed in which interference is measured and the temperature at a plurality of measurement points can be measured simultaneously (see, for example, Patent Document 1). According to such a technique, the temperature of a plurality of measurement points can be measured at a time with a simple configuration.

JP 2006-112826 A

  When measuring the temperature of the substrate being processed by the plasma processing apparatus using the temperature measurement apparatus using the low-coherence interferometer described above, the substrate is placed on a mounting table, and the vacuum chamber is in a vacuum atmosphere Is placed inside. On the other hand, the collimator provided at the exit of the optical fiber for guiding the measurement light is usually placed outside the base plate of the vacuum processing chamber in a normal pressure atmosphere in consideration of maintainability such as optical axis alignment. Fixed.

  Here, the mounting table on which the substrate is mounted includes an electrostatic chuck mechanism for attracting the substrate, an RF plate for applying high-frequency power, and the like, and these components are substantially in a vacuum atmosphere. And a normal pressure atmosphere. Also, at the lower part of the mounting table, there is sufficient space for insulating the RF plate and the base plate, and a semiconductor wafer is received from the transfer arm and placed on the mounting table, or the semiconductor wafer is lifted from the mounting table and transferred to the transfer arm. Since a space for providing the pusher pin drive mechanism is required, there may be a structure in which a space is formed to some extent between the mounting table and the base plate.

  In such a configuration, the mounting table may bend due to a pressure difference between vacuum and normal pressure, or vibration may be generated in the mounting table due to the influence of a cooling temperature adjustment medium flowing inside the mounting table. is there. For this reason, it turned out that the space | interval of a collimator and the board | substrate mounted on the mounting base fluctuate | varied, and there existed a problem that an accurate temperature measurement was not performed. Further, since the space between the RF plate and the base plate is the atmosphere, it has been found that there is a problem that the air fluctuation affects the optical path and the measurement accuracy deteriorates.

  In addition, the problem that the air fluctuation affects the optical path and the measurement accuracy is deteriorated is also a problem when measuring the temperature of the focus ring provided in the plasma processing apparatus.

  The present invention has been made in response to such a conventional situation, and is capable of measuring the temperature of a substrate or the like with high accuracy, and capable of performing plasma processing of the substrate with higher accuracy and efficiency, and a temperature thereof. It is an object of the present invention to provide a measuring method and a temperature measuring device.

  The plasma processing apparatus of claim 1 includes a vacuum chamber for accommodating a substrate and processing with plasma, a mounting table provided in the vacuum chamber, on which the substrate is mounted, and a front side of the mounting table below the mounting table. A base plate disposed with a table and a gap, a light source, a splitter for dividing light from the light source into measurement light and reference light, and reference light reflection for reflecting the reference light from the splitter Means, an optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means, an optical fiber for irradiating the substrate with the measurement light, and an exit portion of the optical fiber. A temperature measuring means comprising: a collimator; and a photodetector for measuring interference between the measurement light reflected from the substrate and the reference light reflected from the reference light reflecting means. Is a plasma processing apparatus in which a vacuum atmosphere is provided above and the gap between the mounting table and the base plate is a normal pressure atmosphere, so that the measurement light can pass through the upper surface and the lower surface of the mounting table. A temperature measuring window that is optically communicated and hermetically sealed, and a member that connects the mounting table and the base plate is provided in a gap between the mounting table and the base plate; and The collimator is fixed at a position corresponding to the temperature measuring window of the base plate, and the temperature of the substrate can be measured by the temperature measuring means from the temperature measuring window.

  The plasma processing apparatus according to claim 2 is the plasma processing apparatus according to claim 1, wherein the measuring light passes through an optical path of the measuring light between the mounting table and the base plate. Alternatively, a hollow cylindrical body is provided.

  The plasma processing apparatus according to claim 3 is the plasma processing apparatus according to claim 1 or 2, wherein the mounting table is provided with a mirror or a prism that bends the optical path of the measurement light in a lateral direction and a vertical direction. It is possible to measure the temperature of a part above the part where the structure exists between the mounting table and the base plate.

  The plasma processing according to claim 4 is the plasma processing apparatus according to any one of claims 1 to 3, wherein the mounting table includes an RF plate made of a conductive material to which high-frequency power is applied, and the RF plate. And an electrostatic chuck mechanism for adsorbing the substrate.

  The plasma processing according to claim 5 is the plasma processing apparatus according to claim 4, wherein the RF plate and the electrostatic chuck mechanism are fixed at both a peripheral portion and a central portion. To do.

  A plasma processing apparatus according to claim 6 is the plasma processing apparatus according to any one of claims 1 to 3, wherein the mounting table adsorbs the RF plate made of a conductive material to which high-frequency power is applied and the substrate. And an electrostatic chuck mechanism for integrating the structure.

  According to a seventh aspect of the present invention, there is provided a plasma processing apparatus comprising: a vacuum chamber for accommodating a substrate and processing with plasma; a mounting table provided in the vacuum chamber, on which the substrate is mounted; A base plate disposed with a table and a gap, a light source, a splitter for dividing light from the light source into measurement light and reference light, and reference light reflection for reflecting the reference light from the splitter Means, an optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means, an optical fiber for irradiating the substrate with the measurement light, and an exit portion of the optical fiber. Temperature measuring means having a collimator, and a photodetector for measuring interference between the measurement light reflected from the temperature measurement object and the reference light reflected from the reference light reflecting means. A plasma processing apparatus in which the upper side of the mounting table is a vacuum atmosphere, and the gap between the mounting table and the base plate is a normal pressure atmosphere, and the measurement light is transmitted through the upper surface and the lower surface of the mounting table. A temperature measurement window that is optically communicated and hermetically sealed as much as possible is provided, and the collimator is fixed at a position corresponding to the temperature measurement window of the mounting table. From the above, the temperature of the substrate can be measured by the temperature measuring means.

  The plasma processing apparatus according to claim 8 is the plasma processing apparatus according to claim 7, wherein the mounting table is provided on an RF plate made of a conductive material to which high-frequency power is applied, and the RF plate, And an electrostatic chuck mechanism for adsorbing the substrate, wherein the collimator is fixed to the RF plate or the electrostatic chuck mechanism.

  The plasma processing apparatus according to claim 9 is the plasma processing apparatus according to claim 7, wherein the mounting table includes an RF plate made of a conductive material to which high-frequency power is applied and an electrostatic chuck for adsorbing the substrate. A mechanism is integrated with the mechanism, and the collimator is fixed to the RF plate.

  The plasma processing apparatus according to claim 10 is the plasma processing apparatus according to any one of claims 1 to 9, wherein the temperature measurement unit further supplies n first to n-th measurement beams from the splitter. A second splitter for dividing the light into measurement light is provided, and the temperatures of the plurality of parts can be measured by the plurality of measurement light from the second splitter.

  The plasma processing apparatus according to claim 11 is the plasma processing apparatus according to any one of claims 1 to 10, wherein a counter electrode is provided in the vacuum chamber so as to face the mounting table, and the temperature measurement is performed. The means can measure the temperature of the portion of the counter electrode through the temperature measurement window and the substrate on the mounting table.

  The plasma processing apparatus according to claim 12 is provided in a vacuum chamber for accommodating a substrate and processing with plasma, a focus ring installed in the vacuum chamber, and a wall of the vacuum chamber, A window portion through which light can be transmitted inside and outside, a light source, a splitter for dividing light from the light source into measurement light and reference light, and reference light reflecting means for reflecting the reference light from the splitter; An optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means, an optical fiber for irradiating the focus ring with the measurement light, and an exit portion of the optical fiber. A temperature detector comprising: a collimator; and a photodetector for measuring interference between the measurement light reflected from the focus ring and the reference light reflected from the reference light reflecting means. A collimator disposed outside the window, and the measurement light emitted from the collimator is transmitted through the window and provided on the focus ring. The optical path is changed by the optical path changing means and irradiated to the focus ring, and the measurement light reflected by the focus ring is changed by the optical path changing means and returned to the window, and enters the collimator. It is possible to measure the temperature of the focus ring.

  The plasma processing apparatus of claim 13 is the plasma processing apparatus of claim 12, wherein the optical path changing means is a prism.

  A plasma processing apparatus according to a fourteenth aspect is the plasma processing apparatus according to the twelfth or thirteenth aspect, characterized in that the optical path changing means is fixed to a frame portion provided on the focus ring.

  The temperature measurement method according to claim 15 measures the temperature of the focus ring of a plasma processing apparatus including a vacuum chamber for accommodating a substrate and processing with plasma, and a focus ring installed in the vacuum chamber. In the temperature measurement method, a window portion that allows light to pass through the inside and outside of the vacuum chamber is formed in the wall portion of the vacuum chamber, and the light source and the light from the light source are divided into measurement light and reference light A reference light reflecting means for reflecting the reference light from the splitter, an optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means, and the measurement light An optical fiber for irradiating the focus ring, a collimator provided at an exit portion of the optical fiber, and a measurement reflected from the focus ring And a photo detector for measuring interference between the reference light reflected from the reference light reflecting means, and the collimator of the temperature measuring means having the outside is arranged outside the window portion, and the measuring light emitted from the collimator However, the optical path is changed by the optical path changing means provided on the focus ring through the window and irradiated to the focus ring, and the measurement light reflected by the focus ring is changed by the optical path changing means. Then, the temperature of the focus ring is measured so as to return to the window and enter the collimator.

  A temperature measuring method according to a sixteenth aspect is the temperature measuring method according to the fifteenth aspect, wherein the optical path changing means is a prism.

  A temperature measuring method according to a seventeenth aspect is the temperature measuring method according to the fifteenth or sixteenth aspect, wherein the optical path changing means is fixed to a frame portion provided on the focus ring.

  The temperature measurement device according to claim 18 is a temperature measurement device for measuring a temperature of a focus ring installed in a vacuum chamber, and includes a light source and a splitter for dividing light from the light source into measurement light and reference light. A reference light reflecting means for reflecting the reference light from the splitter, an optical path length changing means for changing the optical path length of the reference light reflected from the reference light reflecting means, and the measurement light to the focus ring. An optical fiber for irradiating the optical fiber, a collimator provided at the exit of the optical fiber, and light detection for measuring interference between the measurement light reflected from the focus ring and the reference light reflected from the reference light reflecting means A temperature measuring means having a container, and is emitted from the collimator disposed outside the window portion formed in the wall portion of the vacuum chamber and transmitted through the window portion. Optical path changing means for changing the optical path and irradiating the focus ring with the constant light, and returning the measurement light reflected by the focus ring to the window part after changing the optical path and entering the collimator. And

  A temperature measuring apparatus according to a nineteenth aspect is the temperature measuring apparatus according to the eighteenth aspect, wherein the optical path changing means is a prism.

  The temperature measuring device according to claim 20 is the temperature measuring device according to claim 18 or 19, wherein the optical path changing means is fixed to a frame portion provided on the focus ring.

  According to the present invention, it is possible to provide a plasma processing apparatus, a temperature measuring method, and a temperature measuring apparatus that can accurately measure the temperature of a substrate or the like and can perform plasma processing of the substrate with higher accuracy and efficiency. it can.

The figure which shows the principal part cross-section schematic structure of the plasma processing apparatus concerning embodiment of this invention. The figure which expands and shows the principal part structure of the plasma processing apparatus of FIG. The block diagram which shows schematic structure of the temperature measurement means of the plasma processing apparatus of FIG. The figure for demonstrating the state of reflection of measurement light. The figure for demonstrating the example of an interference waveform. The figure which shows an example of the temperature measurement result in the plasma processing apparatus of FIG. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure for demonstrating the state of reflection of the measurement light from a cell. The figure for demonstrating the state of reflection of the measurement light from a cell. The figure for demonstrating the example of an interference waveform. The flowchart which shows the procedure in the case of measuring the temperature of a cell. The figure which shows an example of the temperature measurement result of a cell and a focus ring. The figure which shows the structure of the modification of the window for temperature measurement. The figure which shows the structure of the modification of the window for temperature measurement. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part cross-sectional schematic structure of the plasma processing apparatus concerning other embodiment of this invention. The figure which shows the principal part schematic structure seen from the side of the plasma processing apparatus concerning the modification of this invention. The figure which shows the principal part schematic structure seen from the upper direction of the plasma processing apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification and drawing, about the component which has the substantially the same function structure, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  FIG. 1 is a diagram schematically showing a longitudinal sectional configuration of a main part of a plasma processing apparatus 1 according to the present embodiment. As shown in FIG. 1, a plasma processing apparatus 1 includes a vacuum chamber 2 for accommodating a semiconductor wafer W as a substrate and processing it with plasma.

  A mounting table 3 for mounting the semiconductor wafer W is provided in the vacuum chamber 2. The mounting table 3 includes an RF plate 4 made of a conductive material, to which high-frequency power is applied, and an electrostatic chuck mechanism 5 provided on the RF plate 4 for attracting the semiconductor wafer W. A power feed rod 6 electrically connected to a high frequency power source (not shown) is connected to the center of the RF plate 4.

  A baffle plate 7 formed in an annular shape is provided around the mounting table 3 so as to surround the mounting table 3, and air is uniformly exhausted from the periphery of the mounting table 3 at the lower part of the baffle plate 7. An annular exhaust space 8 is formed for this purpose. A base plate 9 is provided at the bottom of the vacuum chamber 2, and between the RF plate 4 and the base plate 9. A void 10 is formed. The gap 10 is sufficiently wide to insulate the RF plate 4 from the base plate 9. Also, a pusher pin drive mechanism (not shown) that receives the semiconductor wafer W from the transfer arm and places it on the mounting table 3 or lifts the semiconductor wafer W from the mounting table 3 and delivers it to the transfer arm is provided in the gap 10. ing. In addition, the gap 10 is not a vacuum atmosphere but an air atmosphere.

  A counter electrode 11 is provided above the mounting table 3 so as to face the mounting table 3 with a gap. The counter electrode 11 is configured by a so-called shower head, and is configured to supply a predetermined processing gas in a shower form to the semiconductor wafer W mounted on the mounting table 3. The counter electrode 11 is set to a ground potential or a high frequency power is applied. A focus ring 29 is provided around the semiconductor wafer W on the mounting table 3. The focus ring 29 is for improving the in-plane uniformity of the plasma processing of the semiconductor wafer W.

  The vacuum chamber 2 is configured such that the space above the mounting table 3 is a vacuum atmosphere, and the gap 10 below the mounting table 3 is a normal pressure atmosphere. Therefore, the mounting table 3 constitutes a part of the partition wall that partitions the vacuum atmosphere and the normal pressure atmosphere. A plurality (four in the example shown in FIG. 1) of temperature measuring windows 12 to 15 are formed on the mounting table 3. These temperature measurement windows 12 to 15 have a structure in which the upper surface and the lower surface of the mounting table 3 are optically communicated so as to allow measurement light to pass therethrough and are hermetically sealed.

  In the present embodiment, among the temperature measurement windows 12 to 15, the temperature measurement window 15 provided at the outermost position of the mounting table 3 is for measuring the temperature of the focus ring 29. The other temperature measurement windows 12 to 14 are for measuring the temperature of the semiconductor wafer W.

  FIG. 2 shows the configuration of the temperature measurement windows 12 to 15 in an enlarged manner. As shown in FIG. 2, the mounting table 3 is provided with a through hole 50 that penetrates the RF plate 4 and a through hole 51 that penetrates the electrostatic chuck mechanism 5. The lower end of the through-hole 51 of the electrostatic chuck mechanism 5 is provided with a large-diameter portion 51a in which the inner diameter of the hole is enlarged, and the upper end of the through-hole 50 of the RF plate 4 is increased in diameter toward the upper side. An inclined surface 50a is formed.

  A sleeve 52 is fixed in the through hole 51 of the electrostatic chuck mechanism 5 and is formed in a substantially cylindrical shape. The sleeve 52 is made of ceramic, resin, alumite, or the like. In the sleeve 52, a window material 53 made of a material capable of transmitting measurement light (infrared rays) for temperature measurement, such as quartz or sapphire, and formed in a substantially cylindrical shape is inserted. The window member 53 has a large-diameter portion 53a on the lower end side, and the upper side surface of the large-diameter portion 53a is positioned in contact with the lower side surface of the sleeve 52.

  The large-diameter portion 53a of the window member 53 is provided with a vacuum seal O-ring 54. The vacuum seal O-ring 54 includes the large-diameter portion 53a, the lower surface of the sleeve 52, and the RF plate 4 side. It is pressed between the inclined surface 50a and maintains airtightness. An O-ring 55 is provided between the sleeve 52 and the window material 53 to prevent the window material 53 from sliding off. Further, a buffer material 56 is provided in the through hole 50 so as to be in contact with the large diameter portion 53 a of the window material 53.

  A protective film 57 made of a ceramic plate, polyimide film, sprayed film, alumite, sapphire, or the like is formed on the upper surface of the electrostatic chuck mechanism 5, and temperature measuring windows 12 to 15 are formed on the protective film 57. An opening 58 having a diameter of, for example, about 1 to 3 mm is formed in the formed portion.

  As shown in FIG. 1, the base plate 9 is provided with through holes 16 to 19 corresponding to the temperature measuring windows 12 to 15, respectively, and these through holes are respectively measured from the temperature measuring means. Collimators 24 to 27 provided at exit portions of the optical fibers 20 to 23 for guiding light are fixed. A connecting member 30 that connects the base plate 9 and the mounting table 3 (RF plate 4) is disposed in the gap 10 between the base plate 9 and the mounting table 3 (RF plate 4). In FIG. 1, only one connecting member 30 is illustrated, but a plurality of (for example, four or more) connecting members 30 are arranged along the circumferential direction. These connecting members 30 are for suppressing deformation and vibration of the mounting table 3.

  The optical fibers 20 to 23 are connected to a temperature measuring means 100 configured as shown in FIG. As shown in FIG. 3, the temperature measuring unit 100 includes a light source 110, a first splitter 120 for separating light from the light source 110 into measurement light for measuring temperature and reference light, and the first splitter 120. Are divided into n first to n-th measurement beams (n = 4 in the present embodiment), and a reference for reflecting the reference beam from the first splitter 120. The light reflecting means 140 and the optical path length changing means 150 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 unit 150 includes, for example, a linear stage 151, a servo motor 152, a laser interferometer 153, and the like for moving the reference light reflecting unit 140 configured by a reference mirror or the like in one direction parallel to the incident direction of the reference light. It is configured. Thus, by driving the reference light reflecting means 140 such as a reference mirror in one direction, the optical path length of the reference light reflected from the reference light reflecting means 140 such as the reference mirror can be changed. Servo motor 152 is controlled by controller 170. The signal from the laser interferometer 153 is converted into a digital signal by the A / D converter 172 and input to the controller 170.

  Further, the temperature measuring apparatus 100 reflects the first to fourth measurement lights from the semiconductor wafer W and the focus ring 29 and so on when irradiating the first to fourth measurement points such as the semiconductor wafer W and the focus ring 29 and the like. A photodetector 160 is provided for measuring interference between the first to fourth measurement lights and the reference light reflected from the reference light reflecting means 140 when the reference light reflecting means 140 is irradiated with the reference light.

  As the light source 110, any light can be used as long as interference between the measurement light and the reference light can be measured. In the case of measuring the temperature of the semiconductor wafer W, light that is such that reflected light from at least a distance (usually about 800 to 1500 μm) between the front surface and the back surface of the semiconductor wafer W does not cause interference is 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. Moreover, as coherence length, 0.1-100 micrometers is preferable, for example, and also 3 micrometers or less are more preferable. By using such low-coherence light as the light source 110, it is possible to avoid obstacles due to unnecessary interference, and to easily measure interference with reference light based on reflected light from the surface or inner layer of the semiconductor wafer W. it can.

  As the light source using the low-coherence light, for example, an SLD (Super Luminescent Diode), LED, high-intensity lamp (tungsten lamp, xenon lamp, etc.), ultra-wideband wavelength light source, or the like can be used. Among these low-coherence light sources, it is preferable to use the high-luminance SLD (wavelength, for example, 1300 nm) shown in FIG.

  For example, an optical fiber coupler is used as the first splitter 120. However, the present invention is not limited to this, and any light source that can be divided into reference light and measurement light may be used. For the second splitter 130, for example, an optical fiber coupler is used. However, the present invention is not limited to this, and any material that can be divided into the first to fourth measurement lights may be used. As the first splitter 120 and the second splitter 130, for example, an optical waveguide type demultiplexer, a semi-transparent 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 from the viewpoint of parallelism with incident light of reflected light. However, as long as the reference light can be reflected, the configuration is not limited to the above, and may be configured with a delay line, for example.

  The light detector 160 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 between the measurement light from the temperature measurement object and the reference light from the reference light reflecting means 140 can be measured, the light detector is not limited to the above, and a photodetector using, for example, an avalanche photodiode or a photomultiplier tube 160 may be configured. The detection signal of the photodetector 160 is input to the A / D converter 172 via the amplifier 171, converted into a digital signal, and processed by the controller 170.

  The reference light from the first splitter 120 is transmitted to the reference light irradiation position for irradiating the reference light reflecting means 140 via the optical fiber and the collimator 28. Further, the first to fourth measurement lights from the second splitter 130 are transmitted to the measurement light irradiation position for irradiating the semiconductor wafer W and the focus ring 29 via the optical fibers 20 to 23 and the collimators 24 to 27, respectively. It is like that.

  The temperature measurement unit 100 is configured such that the optical path lengths from the second splitter 130 to the temperature measurement object in the first to fourth measurement lights are different from each other. Specifically, for example, when the lengths of the optical fibers 20 to 23 are the same, for example, the tip surfaces of the collimators 24 to 27, that is, the measurement light irradiation positions are respectively substantially parallel to the irradiation direction from the temperature measurement object. Arranged so as to shift. Further, by changing the lengths of the optical fibers 20 to 23 without shifting the tip surfaces of the collimators 24 to 27, each optical path length from the second splitter 130 to the temperature measurement object in the first to fourth measurement lights. May be different.

  The difference in the optical path lengths from the second splitter 130 to the temperature measurement object in the first to fourth measurement lights is the interference between the first to fourth measurement lights and the reference light measured at least for each measurement point. It is necessary to prevent the waves from overlapping each other. For example, when a low-coherence light source is used as the light source 110, overlapping of interference waves can be prevented if there is a difference between the optical path lengths at least as long as the coherence length of the interference waves. Further, it is preferable to determine such a difference in optical path length in consideration of the thickness of the temperature measurement object, the rate of change of the thickness, the temperature range to be measured, the moving distance of the reference mirror, and the like. Specifically, for example, in the case of a silicon wafer having a thickness of about 0.7 mm, the moving distance of the reference mirror in the temperature range from room temperature to about 200 ° C. is about 0.04 mm. If the difference in optical path length is about 0.1 mm, interference waves at each measurement point can be prevented from overlapping.

  Thereby, the interference wave of the measurement point irradiated with each 1st-4th measurement light can be detected at once only by scanning the reference light reflection means 140 once. For this reason, the time taken for temperature measurement can be shortened as much as possible.

  In the plasma processing apparatus 1 having the above configuration, as shown in FIG. 4, the measurement light for temperature measurement irradiated from the temperature measurement windows 12 to 14 toward the semiconductor wafer W is reflected on the back surface of the semiconductor wafer W. At the same time, the light is reflected on the surface side of the semiconductor wafer W, and interference waves between the reflected light and the reference light are detected.

  That is, as shown in FIG. 5A, when the refractive index of the semiconductor wafer W is n and the thickness of the semiconductor wafer W is d, the back surface of the semiconductor wafer W is located at a distance corresponding to nd. The reflected measurement light interference wave (lower in the figure) and the measurement light interference wave reflected on the surface side of the semiconductor wafer W (upper in the figure) are detected. Since the optical path lengths to the respective measurement points are set to be different from each other, as shown in FIG. 5A, the interference waves of the respective measurement points are located at positions separated by a distance corresponding to the optical path length difference. Peaks are detected. In FIG. 5A, the vertical axis represents the output of the photodetector, and the horizontal axis represents the moving distance of the mirror as the reference light reflecting means. Further, in FIG. 5A, the waveform of the interference wave at each measurement point is indicated by a solid line, a dotted line, a one-dot chain line, and a two-dot chain line with different line types.

  When the temperature of the semiconductor wafer W or the like is measured by the temperature measuring means 100, the initial thickness of the semiconductor wafer W or the like that is a temperature measurement object is measured prior to the temperature measurement. At this time, the waveform as shown in FIG. 5A is obtained, and the initial thickness of the semiconductor wafer W or the like is obtained as the interval between the “lower” and “upper” peaks shown in FIG. The temperature of the semiconductor wafer W or the like is detected by the change in thickness relative to the initial thickness, that is, the change in the interval between the “lower” and “upper” peaks shown in FIG.

  In the temperature measuring unit 100 described above, light from the light source 110 is incident on the first splitter 120 and is divided into measurement light and reference light by the first splitter 120. Among these, the measurement light is divided into first to n-th measurement light by the second splitter 130 and irradiated to a temperature measurement object such as a semiconductor wafer at each measurement point, depending on the surface, boundary surface, and back surface of each layer. Reflected.

  On the other hand, the reference light is reflected by the reference light reflecting means 140. Then, each reflected light of the first to nth measurement lights enters the first splitter 120 via the second splitter 130 and is detected by the photodetector 160 together with the reflected light of the reference light.

  Then, by scanning the reference light reflecting means 140, an interference waveform as shown in FIG. 5A is obtained with the vertical axis representing the output of the photodetector 160 and the horizontal axis representing the movement distance of the reference light reflecting means 140. It is done. Here, as the light source 110, the low-coherence light source as described above 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 at 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 at other places. It has the characteristic of being substantially reduced. For this reason, by moving the reference light reflecting means 140 and changing the optical path length of the reference light, in addition to the surface and the back surface of the temperature measurement object, if there are further layers, the refractive index of each layer is also included. The measurement light reflected by the difference interferes with the reference light.

  Next, a method for measuring the temperature based on the interference wave between the measurement light and the reference light will be described in more detail. As a temperature measuring method based on the interference wave, for example, there is a temperature conversion method using a change in optical path length based on a temperature change. Here, a temperature conversion method using the positional deviation of the interference waveform will be described.

  When a temperature measurement object such as a semiconductor wafer W is heated by the action of plasma or the like, the semiconductor wafer W expands and its refractive index changes, so that the position of the interference waveform shifts before and after the temperature change. The peak-to-peak width of the interference waveform changes. At this time, if there is a temperature change for each measurement point, the position of the interference waveform shifts for each measurement point, and the peak-to-peak width of the interference waveform changes. A temperature change can be detected by measuring the peak-to-peak width of the interference waveform at each measurement point. For example, in the case of the temperature measuring unit 100 as shown in FIG. 3, the peak-to-peak width of the interference waveform corresponds to the moving distance of the reference light reflecting unit 140, and thus the reference light reflecting unit 140 in the peak-to-peak width of the interference waveform. It is possible to detect a change in temperature by measuring the movement distance of.

  When the thickness of the semiconductor wafer W is d and the refractive index is n, the deviation of the peak position with respect to the interference waveform depends on the linear expansion coefficient α specific to each layer with respect to the thickness d, and the change of the refractive index n. Is mainly dependent on the temperature coefficient β of the refractive index change specific to each layer. It is known that the temperature coefficient β of refractive index change also depends on the wavelength.

  Therefore, when the thickness d ′ of the semiconductor wafer W after the temperature change at a certain measurement point P is expressed by a mathematical expression, it is expressed by the following mathematical expression (1). In Equation (1), ΔT represents the temperature change at the measurement point, α represents the linear expansion coefficient, and β represents the temperature coefficient of the refractive index change. D and n represent the thickness and refractive index at the measurement point P before the temperature change, respectively.

d ′ = d · (1 + αΔT), n ′ = n · (1 + βΔT) (1)
As shown in the above formula (1), the optical path length of the measurement light that passes through the measurement point P changes due to the temperature change. The optical path length is generally represented by the product of the thickness d and the refractive index n. Therefore, if the optical path length of the measuring light transmitted through the measuring point P before the temperature change is L, and the optical path length after the temperature at the measuring point is changed by ΔT is L ′, L and L ′ are respectively the following formulas: As shown in (2).

L = d · n, L ′ = d ′ · n ′ (2)
Accordingly, when the difference (L′−L) in the optical path length of the measurement light at the measurement point before and after the temperature change is calculated and organized by the above formulas (1) and (2), the following formula (3) is obtained. . In addition, in the following mathematical formula (3), in consideration of α · β << α and α · β << β, minute terms are omitted.

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

  Here, the optical path length of the measurement light at each measurement point corresponds to the peak-to-peak width of the interference waveform with the reference light. Therefore, if the linear expansion coefficient α and the temperature coefficient β of the refractive index change are examined in advance, by measuring the peak-to-peak width of the interference waveform with the reference light at each measurement point, using the above formula (3), It can be converted into the temperature at each measurement point.

  Thus, when converting the interference wave to the temperature, as described above, 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. 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 the refractive index change of materials including the semiconductor wafer W may depend on the temperature depending on the temperature range. For example, the linear expansion coefficient 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 the semiconductor wafer W, 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. Yes. 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 and the values are taken into consideration. If the temperature is converted, it can be converted to a more accurate temperature.

  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, in the temperature measuring means 100, the temperature is measured based on the optical path length of the measurement light in principle. If the optical path length changes due to a cause other than the temperature change of the temperature measurement target, noise is generated. This makes it difficult to accurately measure the temperature of the temperature measurement target. On the other hand, in the plasma processing apparatus 1 shown in FIG. 1, the temperature measurement windows 12 to 15 are provided on the mounting table 3. It is a pressure atmosphere. For this reason, the mounting table 3 is likely to be vibrated due to the flow of the temperature adjusting medium for cooling flowing in the electrostatic chuck mechanism 5 or the like due to a pressure difference. When the mounting table 3 is bent or vibrated as described above, the distance between the mounting table 3 and the base plate 9 varies, and the distance between the collimators 24 to 27 and the semiconductor wafer W varies. The optical path length in the temperature measuring unit 100 changes.

  For this reason, in this embodiment, the connection member 30 which connects the base plate 9 and the mounting base 3 (RF plate 4) is provided, and the deformation | transformation and vibration of the mounting base 3 can be suppressed. As a result, it is possible to suppress the change in the optical path length in the temperature measuring means 100, and to suppress the generation of noise and to measure the temperature of the semiconductor wafer W or the like with high accuracy. Since the temperature of the semiconductor wafer W or the like during the plasma processing can be measured with high accuracy, the plasma processing with high accuracy can be performed by feeding back the temperature measurement result and controlling the state of the plasma processing. .

  FIG. 6 shows the result of measuring the temperatures at 75 mm, 128 mm, 143 mm, and 158 mm (focus ring) from the center of the semiconductor wafer W by actually generating plasma in the plasma processing apparatus 1 having the above configuration. Is shown. 6A shows the pressure of the cooling helium gas supplied between the mounting table 3 and the back surface of the semiconductor wafer W at 2000 Pa (15 Torr) / 5320 Pa (40 Torr) (the former is the pressure at the center and the periphery). In this case, the temperature of the semiconductor wafer W is increased from 20 ° C. to 65 ° C. to 75 ° C. by igniting plasma. Rose to ℃. On the other hand, FIG. 6B shows a case where the pressure of the helium gas is set to 0 Pa and the supply is not performed. In this case, the temperature of the semiconductor wafer W exceeded 110 ° C. at a position 75 mm and a position 143 mm from the center of the wafer W. The temperature of the focus ring did not change with or without helium gas.

  As described above, the connecting member that connects the base plate 9 and the mounting table 3 (RF plate 4) is not limited to the shape shown in FIG. 1, and any shape may be used. Further, as shown in FIG. 7, a cylindrical member 30 a formed in a cylindrical shape such as a hollow cylindrical shape may be disposed so as to surround the optical path of each measurement light. With such a configuration, the flow of air and the like in the cylindrical member 30a can be suppressed, the state of the optical path of the measurement light can be maintained in a good state, and noise caused by the flow of air and the like Can be suppressed. That is, as described above, since the gap 10 between the RF plate 4 and the base plate 9 is the atmosphere, it is possible to suppress the air fluctuation from affecting the optical path and deteriorating the measurement accuracy.

  Further, instead of the cylindrical member 30a, as shown in FIG. 8, a material capable of transmitting measurement light inside, for example, a columnar rod 30b made of quartz, sapphire, or the like can be used.

  Incidentally, the RF plate 4 and the electrostatic chuck mechanism 5 constituting the mounting table 3 are usually fastened only at the peripheral edge. For this reason, even if the RF plate 4 and the base plate 9 are connected by the connecting member, the RF plate 4 and the electrostatic chuck mechanism 5 may be deformed so as to be separated from each other, or may vibrate. For this reason, as shown in FIG. 9, it is preferable that the RF plate 4 and the electrostatic chuck mechanism 5 are fastened near the center of the power supply rod 6 or the like by screws 30c or the like. The power feed rod 6 and the RF plate 4 are fastened by a fastening mechanism (not shown).

  Here, as described above, in the portion where the structure exists between the RF plate 4 and the base plate 9 such as the central portion where the feeding rod 6 is provided at the lower part of the RF plate 4, the structure shown in FIG. It is difficult to provide the temperature measurement windows 12 to 15 and the like, and it is difficult to measure the temperature near the center of the semiconductor wafer W. For this reason, as shown in FIG. 10, the optical path of the measurement light is once bent in the horizontal direction by two mirrors 40 and the like from the temperature measurement window 12a and the like arranged so as to be positioned above the power feed rod 6. It can also be configured to measure the temperature near the center of the semiconductor wafer W.

  Also, as shown in FIG. 11, two prisms 41 are used, or an integrated prism 42 is used as shown in FIG. The temperature in the vicinity of the center of the semiconductor wafer W can also be measured from the temperature measurement window 12a or the like disposed so as to be located at the center. Such a configuration can be similarly applied to, for example, the case of measuring the temperature of the periphery of the mounting table 3 on which the focus ring 29 is disposed. The same applies to the case of measuring the temperature of the semiconductor wafer W from the counter electrode 11 side.

  In each of the above-described embodiments, the case where the collimators 24 to 27 are fixed to the base plate 9 has been described. However, as in the embodiment illustrated in FIG. 13, the collimators 24 to 27 are mounted on the mounting table 3 (RF plate 4 in FIG. 13). It can also be set as the structure fixed to. With such a configuration, the collimators 24 to 27 can be brought closer to the semiconductor wafer W or the like that is a temperature measurement target, and fluctuations in the optical path length of the measurement light due to deformation or vibration of the mounting table 3 can be reduced. Can be suppressed more. In this case, the air fluctuation in the gap 10 between the RF plate 4 and the base plate 9 does not affect the optical path and the measurement accuracy does not deteriorate.

  Although FIG. 13 shows the case where the collimators 24 to 27 are fixed to the RF plate 4, the collimators 24 to 27 may be fixed to the electrostatic chuck mechanism 5. With such a configuration, it is possible to further suppress fluctuations in the optical path length of the measurement light due to deformation and vibration of the mounting table 3. However, in this case, maintainability such as adjustment of the optical path by the collimators 24 to 27 is impaired.

  As shown in FIG. 1, an upper electrode 11 is provided in the vacuum chamber 2 above the mounting table 3 so as to face the mounting table 3. In some cases, a cell made of a material that can transmit infrared rays such as silicon is disposed on the surface of the upper electrode 11 facing the mounting table 3. In such a case, as shown in FIG. 14, the measurement light is irradiated from the temperature measurement windows 12 to 14 (and the temperature measurement window 15) to the cell 11a via the semiconductor wafer W (and the focus ring 29). By measuring the reflected light from the lower side surface and the upper side surface of the cell 11a, the temperature of the cell 11a can be measured.

  In this case, when the thickness of the semiconductor wafer W is d, the refractive index is n, the distance from the semiconductor wafer W to the cell 11a is L, the thickness of the cell 11a is D, and the refractive index is N, As shown in FIG. 5B, after the interference signal from the lower surface of the semiconductor wafer W is detected, the interference signal from the lower surface of the cell 11a is detected at a position separated by a distance corresponding to L + nd. Further, after an interference signal from the lower surface of the cell 11a is detected, an interference signal from the upper surface of the cell 11a is detected at a position separated by a distance corresponding to ND. And the temperature of the cell 11a can be measured from the change in the distance between the interference signal from the lower surface of the cell 11a and the interference signal from the upper surface.

  Further, as shown in FIG. 15, when the semiconductor wafer W is removed from the mounting table 3, as shown in FIG. 16, the case without the semiconductor wafer W (a), the case with the semiconductor wafer W (b), Thus, since the interference position of the reflected light from the cell 11a is shifted by (n-1) d0, it is necessary to change the initial position.

  FIG. 17 is a flowchart showing a procedure for measuring the temperature of the cell 11a. As shown in the figure, first, the temperature of the mounting table and the cell is set (step 170), and the initial position X0 and the initial thickness D0 of the surface of the cell 11a are measured without the semiconductor wafer W (in FIG. Step 171).

  Next, a process of setting the initial position of the surface of the cell 11a to X1 is performed (step 172).

  Next, the semiconductor wafer W is loaded and placed on the mounting table 3 (step 173), and the initial position x0 and the initial thickness d0 of the lower surface of the semiconductor wafer W are measured (step 174).

  Thereafter, temperature measurement is started with the initial position of the surface of the cell 11a as X1, the initial thickness as D0, the initial position x0 of the lower surface of the semiconductor wafer W, and the initial thickness d0 (step 175).

  FIG. 18 shows an example of the results of measuring the temperature (a) of the cell 11a and the temperature (b) of the focus ring 29 during the plasma processing by the above-described steps. As shown in the figure, the temperature of the cell 11a rises to 220 ° C. or higher. The temperature of the focus ring 29 is about 80 to 90 ° C.

  As described above, since not only the temperature of the semiconductor wafer W but also the temperature of the cell 11a and the focus ring 29 can be measured, it becomes possible to control the plasma processing process more precisely, and more accurate plasma. Processing can be performed. In addition, since the degree of wear of the cell 11a and the focus ring 29 can be monitored at the same time, it is possible to know the replacement time of the cell 11a and the focus ring 29, and plasma according to the degree of wear of the cell 11a and the focus ring 29. It is also possible to control the process of processing. In this case, it becomes possible to use the cell 11a and the focus ring 29 for a longer period of time, and it is possible to reduce the running cost by extending the life of the cell 11a and improve the productivity by improving the operating rate of the apparatus. .

  FIG. 19 shows a configuration of a modified example of the temperature measurement windows 12 to 15. In the temperature measurement window shown in FIG. 19A, a protruding portion 52b protruding inward is provided at the upper end portion of the sleeve 52, and the window material 53 is supported by the protruding portion 52b. Yes. Further, the protective film 57 is provided up to the upper side of the sleeve 52.

  In the temperature measurement window shown in FIG. 19B, the sleeve 52 does not include the above-described protruding portion 52 b, and the periphery of the upper end of the window material 53 is in contact with the protective film 57. Further, in the temperature measurement window shown in FIG. 19C, the sleeve 52 does not have the protruding portion 52b described above, and the protective film 57 is not in contact with the peripheral edge portion of the upper end of the window material 53. The upper end of the material 53 extends to the surface of the electrostatic chuck mechanism 5.

  The temperature measurement window shown in FIG. 19D has a structure in which the upper end of the sleeve 52 provided with the protruding portion 52b extends to the surface of the electrostatic chuck mechanism 5 as in the case of FIG. ing. Further, the temperature measurement window shown in FIG. 19 (e) uses a sleeve 52 without a protruding portion 52b as in FIG. 19 (b), and its upper end extends to the surface of the electrostatic chuck mechanism 5. It has a structure.

  The temperature measurement window shown in FIG. 19 (f) has a structure in which the surface of the sleeve 52 provided with the protrusion 52 b is covered with a protective film 57 as in the case of FIG. 19 (a). In addition, the temperature measurement window shown in FIG. 19G has a structure in which a sleeve 52 without a protruding portion 52 b is used and the surface thereof is covered with a protective film 57 as in the case of FIG. ing.

  Further, the temperature measurement window shown in FIG. 19 (h) uses the sleeve 52 without the projecting portion 52b as in the case of FIG. 19 (g), the surface is covered with the protective film 57, and the inside of the sleeve 52 is covered. The window material 53 is not provided. In this case, vacuum cutting is performed by the protective film 57 provided on the surface, and it is necessary to make the protective film 57 a material having a strength capable of withstanding the pressure difference.

  Note that the temperature measurement windows 12 to 15 are not limited to those having the above-described configuration, and various modifications can be made. For example, as shown in FIGS. 20 (a) and 20 (b), the upper end of the sleeve 52 is provided with a stepped portion 52c that expands outward, and the upper end has a flange 53b that protrudes outward. The window material 53 can also be configured to be supported by bringing the flange portion 53b into contact with the stepped portion 52c. In this case, as shown in FIG. 20B, the window material 53 can be detached from the surface side of the electrostatic chuck mechanism 5, for example, when the window material 53 becomes dirty, damaged, worn, or the like. Can be easily replaced. In FIG. 20, reference numeral 54 denotes a vacuum seal O-ring.

  In each of the above embodiments, as shown in FIG. 1 and the like, the mounting table 3 is made of a conductive material, is provided with an RF plate 4 to which high-frequency power is applied, and is provided on the RF plate 4. The case of the configuration including the electrostatic chuck mechanism 5 for adsorbing the liquid has been described. However, for example, as shown in FIG. 21, the mounting table 3a can be similarly applied to the plasma processing apparatus 1 in which the RF plate 4a and the electrostatic chuck mechanism 5a are integrated. In this case, as shown in FIG. 22, the plasma processing apparatus 1 in which the insulating material 3b is provided below the mounting table 3a in which the RF plate 4a and the electrostatic chuck mechanism 5a are integrated. Can be applied in the same manner. 21 and 22, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  Next, with reference to FIGS. 23 and 24, a configuration of a modified example of the present invention will be described. FIG. 23 is a diagram illustrating a schematic configuration of a modified example viewed from the side, and FIG. 24 is a diagram illustrating a schematic configuration viewed from above. Also in this modified example, the temperature measuring unit configured similarly to the temperature measuring unit 100 shown in FIG. 3 and performing temperature measurement using light from the light source 110 is the same as in the above-described embodiment. .

  As shown in FIGS. 23 and 24, in this modification, a window portion (temperature measurement window) 210 through which light can be transmitted between the inside and outside of the vacuum chamber 2 is formed on the side wall portion of the vacuum chamber 2. A prism 220 as an optical path changing unit is provided on the focus ring 29. The prism 220 is fixed to the focus ring 29 by a quartz frame 221. The installation position of the prism 220 is preferably a position close to the window part 210, and most preferably on the focus ring 29 closest to the window part 210. The optical path changing means is not limited to the prism 220, and any optical path changing means may be used as long as the optical path of the measuring light can be changed efficiently.

  A collimator 27 to which the optical fiber 23 is connected is provided outside the window 210, and measurement light from a light source (not shown) is emitted from the collimator 27 through the optical fiber 23, and is transmitted through the window 210 to pass through the vacuum chamber 2. Incidently enter. The incident measurement light is irradiated to the focus ring 29 by changing the optical path toward the lower side at a substantially right angle by the prism 220 as indicated by an arrow in FIG. 23, and the measurement light reflected by the focus ring 29 is The optical path is changed substantially horizontally at a right angle by the prism 220, returned to the window portion 210, and incident on the collimator 27. Then, this measurement light is sent from the collimator 27 to the photodetector (not shown) of the temperature detection means through the optical fiber 23, and the temperature is measured in the same manner as in the above-described embodiment. According to such a configuration, since the measurement light does not pass through the air atmosphere, the air fluctuation does not affect the optical path, and the measurement accuracy does not deteriorate. In addition, significant processing of the mounting table 3 as in the above-described embodiment is unnecessary, and if the etching end point detection window is shared, there is no need to newly provide the window 210 in the vacuum chamber 2, The temperature of the focus ring 29 can be measured easily.

  Note that a plurality of the prisms 220 and the like may be provided to measure temperatures at a plurality of locations on the focus ring 29. In this case, a set of a plurality of optical fibers 23 and a collimator 27 may be provided on the outside of one window 210, and the angle may be changed to irradiate measurement light toward another prism 220. Further, two window portions 210 may be provided at intervals of, for example, 180 °, and the temperature at a position 180 ° away from the focus ring 29 from these window portions 210 may be measured.

  In the embodiment shown in FIG. 1 and the like described above, the temperature of the semiconductor wafer W is measured at three locations and the temperature of the focus ring 29 is measured at one location. Of these, only the temperature of the focus ring 29 is measured. The measurement can also be performed as in the above modification. In this modification, optical path conversion means such as a prism 220 must be provided on the focus ring 29, so that, for example, product manufacturing is performed rather than application to temperature measurement during normal plasma processing in which the product is manufactured. Use in the previous evaluation stage is the main purpose of use.

  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 this example. 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.

  DESCRIPTION OF SYMBOLS 1 ... Plasma processing apparatus, 2 ... Vacuum chamber, 3 ... Mounting stand, 4 ... RF plate, 5 ... Electrostatic chuck mechanism, 6 ... Feeding rod, 7 ... Baffle plate, 8 ... Exhaust space 9 ... Base plate, 10 ... Air gap, 11 ... Counter electrode, 12-15 ... Temperature measurement window, 20-23 ... Optical fiber, 24-27 ... Collimator, 29 ... Focus ring, 30 ... ... Connecting member, W ... Semiconductor wafer.

Claims (20)

A vacuum chamber for containing the substrate and processing with plasma;
A mounting table provided in the vacuum chamber and on which a substrate is mounted;
Below the mounting table, a base plate disposed with a gap from the mounting table,
A light source, a splitter for dividing light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference light reflected from the reference light reflecting means Optical path length changing means for changing the optical path length, an optical fiber for irradiating the substrate with the measurement light, a collimator provided at an exit portion of the optical fiber, the measurement light reflected from the substrate, and the reference A temperature measuring means for measuring interference with the reference light reflected from the light reflecting means, and a vacuum atmosphere is provided above the mounting table, and the mounting table and the base plate A plasma processing apparatus in which the gap between them is an atmospheric pressure atmosphere,
Providing a temperature measurement window optically communicating with the upper and lower surfaces of the mounting table so that the measurement light can be transmitted and hermetically sealed;
In the gap between the mounting table and the base plate, a member for connecting the mounting table and the base plate is provided, and
Fixing the collimator at a position corresponding to the temperature measurement window of the base plate;
The plasma processing apparatus, wherein the temperature of the substrate can be measured by the temperature measuring means from the temperature measuring window. The plasma processing apparatus according to claim 1,
A plasma processing apparatus, wherein a rod or a hollow cylindrical body through which the measurement light can pass is provided in an optical path of the measurement light between the mounting table and the base plate. The plasma processing apparatus according to claim 1 or 2,
The mounting table is provided with a mirror or a prism that bends the optical path of the measurement light in a lateral direction and a vertical direction, and the temperature of a portion above the portion where the structure exists between the mounting table and the base plate is set. A plasma processing apparatus characterized in that measurement is possible. The plasma processing apparatus according to any one of claims 1 to 3,
An RF plate made of a conductive material to which high-frequency power is applied;
A plasma processing apparatus, comprising: an electrostatic chuck mechanism provided on the RF plate for adsorbing the substrate. The plasma processing apparatus according to claim 4,
A plasma processing apparatus, wherein the RF plate and the electrostatic chuck mechanism are fixed at both a peripheral part and a central part. The plasma processing apparatus according to any one of claims 1 to 3,
The plasma processing apparatus, wherein the mounting table is configured such that an RF plate made of a conductive material to which high-frequency power is applied and an electrostatic chuck mechanism for adsorbing the substrate are integrated. A vacuum chamber for containing the substrate and processing with plasma;
A mounting table provided in the vacuum chamber and on which a substrate is mounted;
Below the mounting table, a base plate disposed with a gap from the mounting table,
A light source, a splitter for dividing light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference light reflected from the reference light reflecting means Optical path length changing means for changing the optical path length, an optical fiber for irradiating the substrate with the measurement light, a collimator provided at an exit portion of the optical fiber, the measurement light reflected from the substrate, and the reference A temperature measuring means for measuring interference with the reference light reflected from the light reflecting means, and a vacuum atmosphere is provided above the mounting table, and the mounting table and the base plate A plasma processing apparatus in which the gap between them is an atmospheric pressure atmosphere,
Providing a temperature measurement window optically communicating with the upper and lower surfaces of the mounting table so that the measurement light can be transmitted and hermetically sealed;
Fixing the collimator at a position corresponding to the temperature measurement window of the mounting table,
The plasma processing apparatus, wherein the temperature of the substrate can be measured by the temperature measuring means from the temperature measuring window. The plasma processing apparatus according to claim 7, wherein
An RF plate made of a conductive material to which high-frequency power is applied;
An plasma processing apparatus, comprising: an electrostatic chuck mechanism provided on the RF plate for adsorbing the substrate; and the collimator being fixed to the RF plate or the electrostatic chuck mechanism. The plasma processing apparatus according to claim 7, wherein
The mounting table is configured such that an RF plate made of a conductive material to which high-frequency power is applied and an electrostatic chuck mechanism for adsorbing the substrate are integrated.
The plasma processing apparatus, wherein the collimator is fixed to the RF plate. The plasma processing apparatus according to claim 1,
The temperature measuring means includes a second splitter for further dividing the measurement light from the splitter into n first to n-th measurement lights, and a plurality of parts are obtained by the plurality of measurement lights from the second splitter. It is possible to measure the temperature of the plasma processing apparatus. The plasma processing apparatus according to claim 1,
A counter electrode is provided in the vacuum chamber so as to face the mounting table, and the temperature measuring means controls the temperature of the portion of the counter electrode through the temperature measuring window and the substrate on the mounting table. A plasma processing apparatus characterized in that it can be measured. A vacuum chamber for containing the substrate and processing with plasma;
A focus ring installed in the vacuum chamber;
A window provided on a wall of the vacuum chamber, and capable of transmitting light between the inside and outside of the vacuum chamber;
A light source, a splitter for dividing light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference light reflected from the reference light reflecting means An optical path length changing means for changing an optical path length; an optical fiber for irradiating the focus ring with the measurement light; a collimator provided at an exit portion of the optical fiber; and a measurement light reflected from the focus ring; A temperature detector having a photodetector for measuring interference with reference light reflected from the reference light reflecting means;
A plasma processing apparatus comprising:
The collimator is disposed outside the window portion, and the measurement light emitted from the collimator is transmitted through the window portion, the optical path is changed by the optical path changing means provided on the focus ring, and the focus ring is irradiated. The temperature of the focus ring can be measured so that the measurement light reflected by the focus ring is changed in optical path by the optical path changing means, returned to the window, and incident on the collimator. Plasma processing equipment. The plasma processing apparatus according to claim 12, wherein
The plasma processing apparatus, wherein the optical path changing means is a prism. The plasma processing apparatus according to claim 12 or 13,
The plasma processing apparatus, wherein the optical path changing means is fixed to a frame portion provided on the focus ring. A vacuum chamber for containing the substrate and processing with plasma;
A temperature measurement method for measuring a temperature of the focus ring of a plasma processing apparatus including a focus ring installed in the vacuum chamber,
While forming a window portion through which light can be transmitted inside and outside the vacuum chamber on the wall portion of the vacuum chamber,
A light source, a splitter for dividing light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference light reflected from the reference light reflecting means An optical path length changing means for changing an optical path length; an optical fiber for irradiating the focus ring with the measurement light; a collimator provided at an exit portion of the optical fiber; and a measurement light reflected from the focus ring; A photo detector for measuring interference with the reference light reflected from the reference light reflecting means, and the collimator of the temperature measuring means having an outside of the window portion,
The measurement light emitted from the collimator is transmitted through the window portion, the optical path is changed by an optical path changing unit provided on the focus ring, irradiated to the focus ring, and the measurement light reflected by the focus ring is A temperature measuring method characterized in that the temperature of the focus ring is measured so that the optical path is changed by the optical path changing means, returns to the window, and enters the collimator. The temperature measurement method according to claim 15, comprising:
The temperature measuring method, wherein the optical path changing means is a prism. The temperature measuring method according to claim 15 or 16,
The temperature measuring method, wherein the optical path changing means is fixed to a frame provided on the focus ring. A temperature measuring device for measuring the temperature of a focus ring installed in a vacuum chamber,
A light source, a splitter for dividing light from the light source into measurement light and reference light, reference light reflecting means for reflecting reference light from the splitter, and reference light reflected from the reference light reflecting means An optical path length changing means for changing an optical path length; an optical fiber for irradiating the focus ring with the measurement light; a collimator provided at an exit portion of the optical fiber; and a measurement light reflected from the focus ring; A temperature detector having a photodetector for measuring interference with reference light reflected from the reference light reflecting means;
Measurement light emitted from the collimator disposed outside the window formed on the wall of the vacuum chamber and transmitted through the window is irradiated to the focus ring by changing the optical path, and reflected by the focus ring. An optical path conversion means for changing the optical path of the measurement light and returning it to the window part so as to be incident on the collimator. The temperature measuring device according to claim 18, wherein
The temperature measuring device, wherein the optical path changing means is a prism. The temperature measuring device according to claim 18 or 19,
The temperature measuring device, wherein the optical path changing means is fixed to a frame provided on the focus ring.

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