This application is based upon and claims the benefit of priority front Japanese Patent Application No. 2017-046030, filed on Mar. 10, 2017; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a sensing system, a sensing wafer, and a plasma processing apparatus.
In order to monitor temperature in a plasma process, there is a method in which a thermo couple or thermo-label is provided in a plasma processing apparatus.
In general, according to one embodiment, a sensing system includes a waveguide, an optical system, and a detector. The waveguide is configured to guide light in a wafer. The optical system is configured to cause the light guided by the waveguide to go out from a back side of the wafer. The detector is configured to detect a state inside or outside the wafer based on a detection result about the light caused to go out by the optical system.
Exemplary embodiments of a sensing system, a sensing wafer, and a plasma processing apparatus will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments.
As illustrated in
Hereinafter, an explanation will be given of a method of using the sensing wafer WS to measure a temperature inside the chamber 1 during a plasma process.
For the substrate of the wafer W and the substrate of the sensing wafer WS, the same material may be used. For example, where the substrate of the wafer W is Si, Si may be used as the substrate of the sensing wafer WS. Where the substrata of the wafer W is GaAs, GaAs may be used as the substrate of the sensing wafer WS. Where the substrate of the wafer W is quartz, quartz may be used as the substrate of the sensing wafer WS.
When the temperature is to be measured by the sensing wafer WS, the process conditions may be set the same as those for forming devices on the wafer W. For example, in a case where management is conducted on the temperature for performing a hole process to a stacked structure of SiO2 and SiN on the wafer W, the same power and etching gas as those of the hole process on the wafer N may be supplied when the temperature is to be measured by the sensing wafer WS.
Here, an explanation will be given of a case where the sensing wafer WS has been placed inside the chamber 1.
Inside the chamber 1, a pedestal 2 for holding the sensing wafer WS is provided. The chamber 1 and the pedestal 2 may be made of a conductive material, such as aluminum (Al). The chamber 1 may be grounded. The pedestal 2 is held by a support body 5 inside the chamber 1. An insulating ring 3 is provided around the pedestal 2. At the boundary between the pedestal and the insulating ring 3, a focus ring (which will also be referred to as “edge ring”) 4 is embedded along the outer periphery of the sensing wafer WS. The focus ring 4 can prevent an electric field from being deflected at the peripheral edge of the sensing wafer WS. The focus ring 4 can be replaced.
A showerhead 6 is provided on the upper part inside the chamber 1. The showerhead 6 can spout a gas G1 toward the wafer surface from above the sensing wafer WS. The showerhead 6 may include spout holes 7 for spouting the gas G1. A piping line 8 for supplying the gas G1 into the showerhead 6 is provided above the showerhead 6. The gas G1 can develop a plasma etching process inside the chamber 1. Here, the showerhead 6 is configured to serve as an upper electrode in plasma generation. The pedestal 2 is configured to serve as a lower electrode in plasma generation. An exhaust piping line 9 is provided at a lower part of the chamber 1.
The pedestal 2 is equipped with an electrostatic chuck 13 for fixing the sensing wafer WS, at the top. The electrostatic chuck 13 includes a chuck electrode 15 embedded therein, where the chuck electrode 15 can generate an electrostatic force for attracting the sensing wafer WS. Accordingly, the pedestal 2 and the electrostatic chuck 13 serve as a wafer holder for holding the sensing wafer WS, inside the chamber 1 in which plasma is generated.
An uneven surface 14 is provided on the front side of the electrostatic chuck 13. The uneven surface 14 may be formed of an emboss-processed surface. The uneven surface 14 is provided to allow a heat transfer medium supplied to the back side of the sensing wafer WS to be diffused entirely over the back side of the sensing wafer WS. As the heat transfer medium, for example, Helium(He) gas may be used. An opening 1A and a shutter 24 are provided on the lateral side of the chamber 1. The shutter 24 can be slid up and down. The opening 1A is opened and closed by sliding the shutter 24 up and down.
The pedestal 2 and the electrostatic chuck 13 (wafer holder) include through holes 10 and 11 formed therein. The through hole 10 can be used as a passage that allows an incoming light Li emitted from below the pedestal 2 to come in from the back side of the sensing wafer WS, and allows an outgoing light Le emitted from the back side of the sensing wafer WS to go out downward from the pedestal 2. The through hole 10 can also be used as a passage to supply the heat transfer medium to the back side of the sensing wafer SIS. Each through hole 11 is provided with a pin 12 inside. The pin 12 can be moved up and down. The sensing wafer WS can be moved up and down by moving the pins 12 up and down, when the sensing wafer WS is to be transferred.
Further, the plasma etching apparatus is equipped with a high-frequency RF power supply 19, a low-frequency RF power supply 22, and a chucking power supply 23. The low-frequency RF power supply 22 can apply a first frequency voltage to the pedestal 2 in a continuous or pulsed form. The high-frequency RF power supply 19 can apply a second frequency voltage to the pedestal 2 in a continuous or pulsed form. The second frequency may be set higher than the first frequency. For example, the first frequency may be set to 13.56 MHz or less, and the second frequency may be set to 40 MHz or more.
Here, the second frequency voltage can be used to generate high density plasma inside the chamber 1. The first frequency voltage can be used to control ion energy generated inside the chamber 1. The chucking power supply 23 can apply a chucking voltage to the chuck electrode 15. The chucking voltage can be used to perform chucking cif the sensing wafer WS onto the electrostatic chuck 13.
The low-frequency RF power supply 22 is connected to the pedestal 2 through a matching device 21 and a blocking capacitor 20 in this order. The high-frequency RF power supply 19 is connected to the pedestal 2 through a matching device 18 and a blocking capacitor 17 in this order. The chucking power supply 23 is connected to the chuck electrode 15. The blocking capacitors 17 and 20 can block DC current generated by polarization of electric charges in plasma, and thereby generate a self-bias electric potential. The matching device 18 can achieve impedance matching with respect to the load of the high-frequency RF power supply 19. The matching device 21 can achieve impedance matching with respect to the load the low-frequency RF power supply 22.
Further, at the bottom of the chamber 1, an opening 1B and a viewport 25 are provided. The viewport 25 may be made of a transparent material, such as quartz. The viewport 25 may be arranged at the position of the opening 1B. The viewport 25 may be fixed to the chamber 1 by screws 27 through a frame 26 that presses the cuter edge of the viewport 25. In this case, in order to ensure the airtightness inside the chamber 1, an O-ring 26 may be fitted between the viewport 25 and the bottomthe chamber 1.
As illustrated in
An excitation light emitter 63 is arranged at the distal end of each passage 61. The excitation light emitter 63 can emit an outgoing light Le on the basis of the incoming light Li. In this case, the outgoing light Le can have a temperature characteristic. The excitation light emitter 63 may be made of a fluorescent substance that generates fluorescence or phosphorescence as the outgoing light Le. As the fluorescent substance, for example, Y2O3:Eu(Europium), Mg4FGeO6:Mn(Manganum), YAG (Yttrium Aluminum Garnet):Dy (Dysprosium), or YAG:Tb (Terbium) may be used. Further, in place of the excitation light emitter 63, for example, a single-crystalline semiconductor, such as GaAs (Gallium Arsenicum), different in kind from the wafer substrate may be used, such that the single-crystalline semiconductor can generate lattice vibration by irradiation with visible light and has temperature dependence in light absorption wavelength due to the lattice vibration.
Further, in each passage 61, an optical fiber 64 is provided to extend from the excitation light emitter 63 to the passage 62. As illustrated in
Reflecting mirrors are arranged at the distal end of the passage 62. Further, a collimation lens 65 is provided in the passage 62. As he material of the collimation lens 65, for example, quartz may be used. The collimation lens 65 ay be arranged below the reflecting mirrors 66.
Here, as illustrated in
Further, as illustrated in
At the central portion of the stage ST2, an opening K2 is formed to penetrate the stage ST2 in the thickness direction. The opening K2 is provided with a transmission window 48 on the front side, which transmits the incoming light Li and the outgoing light Le. As the transmission window 48, transparant and heat conductive materials, for example, AlN or AlON may be used.
Below the stage ST2, a light source 29, a half mirror 30, a light-filter 31, a light detector 32, and a temperature calculator 33 are provided. The light source 29 generates an incoming light Li to be incident onto the excitation light emitters 63. The half mirror 30 reflects the incoming light Li, and transmits the outgoing light Le. The light-filter 31 transmits a wavelength component of the outgoing light Le, and attenuates the other wavelength components. For example, where the incoming light Li is blue light and the outgoing light Le is red light, a red filter may be used as the light-filter 31. The light detector 32 detects the outgoing light Le. The temperature calculator 33 calculates the temperature of the sensing wafer WS on the basis of a temperature characteristic of the outgoing light Le.
The light rce 29, the half mirror 30, the light-filter 31, the light detector 32, and the temperature calculator 33 may be arranged outside the chamber 1 of
Next, an explanation will be given of a method of measuring a temperature during a plasma process inside the chamber by using the sensing wafer WS.
With reference to
Further, a heat transfer medium is supplied to the back side of the sensing wafer WS, and is diffused entirely over the back side of the sensing wafer WS through the uneven surface 14, to control the temperature of the sensing wafer WS. Then, while the inside of the chamber 1 is exhausted through the exhaust piping line 9, a gas G1 is spouted from the showerhead 6. Then, the second frequency voltage is supplied from the high-frequency RF power supply 19 to the pedestal 2, and the gas G1 is thereby excited to generate plasma above the sensing wafer WS.
At this time, the first frequency voltage is applied in a continuous or pulsed form from the low-frequency RF power supply 22 to the pedestal 2, to control the energy for attracting ions generated inside the chamber 1 to the sensing wafer WS. Then, ions generated above the sensing wafer WS cause sputtering the sensing wafer WS and/or an ion-assisted reaction on the sensing wafer WS, whereby a plasma etching process is performed.
During the plasma etching process, an incoming light Li is emitted from the light source 29. Then, the incoming light Li is reflected by the half mirror 30, and is then transmitted through the transmission window 48 and the collimation lens 65. Further, the incoming light Li is reflected by the respective reflecting mirrors 66, and then comes into the respective optical fibers 64. As illustrated in
At each excitation light emitter 63, an outgoing light Le is generated in response to the incidence of the incoming light Li, and comes into the corresponding optical fiber 64. The respective outgoing lights Le are guided by the optical fibers 64, and are reflected by the respective reflecting mirrors 66. Further, the outgoing lights Le are condensed by the collimation lens 65 as a condensed outgoing light Le, which is then transmitted through the transmission window 48, and goes out from the back side of the stage ST2. The outgoing light Le going out from the back side of the stage ST2 is transmitted through the half mirror 30, and a desired wavelength component is extracted therefrom by the light-filter 31, and is incident onto the light detector 32, by which the outgoing light Le is detected. The detection result obtained by the light detector 32 is sent to the temperature calculator 33. Upon reception of the detection result from the light detector 32, the temperature calculator 33 calculates the temperature of the sensing wafer WS on the basis of a temperature characteristic of the outgoing light Le. The temperature characteristic of the outgoing light Le may be temperature dependence in the decay time of the outgoing light Le, may have temperature dependency in the wavelength of the outgoing light Le, or may have temperature dependency in the wavelength peak intensity ratio of the outgoing light Le.
Here, the respective outgoing lights Le emitted from the plurality of excitation light emitters 63 can be guided into one passage 62. Then, the respective outgoing lights Le emitted from the plurality of excitation light emitters 63 can be made incident all together onto the light detector 32, for example. In this case, the temperature calculator 33 can calculate the average of the temperatures of a plurality of measurement points of the sensing wafer WS on the basis of the detection results sent from the light detector 32. Alternatively, an optical system used for the plurality of excitation light emitters 63 may be structured such that the respective outgoing lights Le emitted from the excitation light emitters 63 are individually guided to light detectors 32. In this case, the temperatures of the respective measurement points of the sensing wafer WS may be calculated on the basis of the respective outgoing lights Le emitted from the excitation light emitters 63.
Here, as the temperature measurement is performed on the basis of a temperature characteristic of the outgoing light Le, an electric wire for sending temperature measurement values outside the chamber 1 is not required any more to extend through inside the chamber 1. Accordingly, it is possible to measure a temperature inside the chamber 1 without opening the chamber 1 to the atmosphere, and thus to manage the temperature inside the chamber 1 even during a plasma process.
Further, as the temperature measurement is performed on the basis of a temperature characteristic of the outgoing light Le, it is possible to improve the temperature resolution as compared with a method using a thermo-label, and thus to improve the temperature measurement accuracy during a plasma process.
Further, as the temperature measurement is performed on the basis of a temperature characteristic of the outgoing light Le, it is possible to improve the heat resistance and electromagnetic noise resistance. This makes it possible to apply this method to temperature measurement during a plasma process with a high frequency and a high power, while suppressing deterioration of the service life of the sensing wafer WS.
Further, as the excitation light emitters 63 and the optical fibers 64 are provided in the sensing wafer WS, it is possible to measure a temperature under conditions equivalent to conditions for processing the wafer W for forming devices. This makes it possible to measure by the sensing wafer WS a temperature equivalent to the temperature of processing points on the wafer W for forming devices, and thus to improve the processing accuracy on the wafer W for forming devices.
Further, as the excitation light emitters 63 and the optical fibers 64 are provided in the sensing wafer WS, it is possible to easily increase the number of temperature measurement points, and thus to improve the temperature management accuracy inside the chamber 1 during a plasma process, while suppressing the cost increase.
Further, as the passage 62 is formed in the sensing wafer WS, it is possible to allow the incoming light Li to come in from the back side of the sensing wafer WS and to allow the outgoing light Le to go out from the back side. This makes it possible to prevent the incoming light Li and the outgoing light Le from being exposed to plasma during a plasma etching process, and thus to prevent generation of temperature measurement errors due to the light emission from plasma.
Further, as the incoming light Li is caused to come in from the back side of the sensing wafer WS and the outgoing light Le is caused to go out from the back side, it is possible to prevent the transmission window 46 and the collimation lens 65 from being exposed to plasma. This makes it possible to prevent the transmission window 46 and the collimation lens 65 from being clouded or damaged by the plasma, and thus to prevent deterioration of the temperature measurement accuracy.
Further, as the incoming light Li is caused to come in from the back side of the sensing wafer WS and the outgoing light Le is caused to go out from the back side, it is possible to set the light source 29 and the light detector 32 to be closer to the stage ST2, without depending on the size of the chamber in the lateral direction. This makes it possible to shorten the path length of the incoming light Li from the light source 29 to the sensing wafer WS and the path length of the outgoing light Le from the light detector 32 to the sensing wafer WS, and thus to facilitate adjustment of the positions of the light source 29 and the light detector 32.
It should be noted that, in the embodiment described above, the semiconductor manufacturing apparatus is exemplified by a plasma etching apparatus of the capacitive coupling type, the apparatus may be a plasma etching apparatus of the inductively coupled type, or may be a plasma etching apparatus of the microwave ECR (Electron Cyclotron Resonance) type. Further, the semiconductor manufacturing apparatus may be a plasma CVD (Chemical Vapor Deposition) apparatus, or may be applied to an epitaxial apparatus, thermal CVD apparatus, or anneal apparatus, other than the plasma processing apparatus.
Next, a specific explanation will be given of the principle of temperature measurement based on a temperature characteristic of the outgoing light Le.
As illustrated in
However, in the case of Y2O3:Eu, the phosphorescence decay time depends on the atmosphere around the fluorescent substance. On the other hand, in the case of Mg4FGeO6:Mn, the phosphorescence decay time does not depend on the atmosphere around the fluorescent substance. Accordingly, when Y2O3:Eu is used as the fluorescent substance, the fluorescent substance is preferably sealed. On the other hand, when Mg4FGeO6:Mn is used as the fluorescent substance, temperature measurement can be performed with high accuracy even where the fluorescent substance is not sealed.
During a plasma etching process, as illustrated in (a) of
At each excitation light emitter 63, as illustrated in
At this time, as illustrated in
Here,
As illustrated in
On the other hand, as illustrated in
Here, there is a structure in which the excitation light emitters 63 are provided at a plurality of places of the sensing wafer WS, and the reflecting mirrors 66 are arranged in a two-dimensional state at the central portion of the sensing wafer WS to correspond to the respective excitation light emitters 63, such that the incoming lights Li and the outgoing lights Le can be individually guided for the respective excitation light emitters 63, to measure the temperatures of a plurality of places of the sensing wafer WS. In this structure, some outgoing lights Le reflected by reflecting mirrors 66 adjacent to each other may cause interference among them.
Next, an explanation will be given of a method for preventing the interference among outgoing lights Le reflected by reflecting mirrors 66, even where the excitation light emitters 63 are provided at a plurality of places of the sensing wafer WS d the intervals of the reflecting mirrors 66 are small.
As illustrated in
Respective incoming lights LiA to LiC vertically coming into the back side of the sensing wafer WS are reflected by the reflecting mirrors 66A to 66C in the horizontal direction, and come into the optical fibers 64A to 64C, respectively. Respective outgoing lights LeA to LeC guided by the optical fibers 64A to 64C in the horizontal direction are reflected by the reflecting mirrors 66A to 66C in the vertical direction, and go out from the back side of the sensing wafer WS. Here, it is assumed that detection points PA to PC are arranged at positions where the respective outgoing lights LeA to LeC can interfere with each other because of the spreads of the respective outgoing lights LeA to LeC.
At this ime, the respective incoming lights LiA to LiC can be set to come into the optical fibers 64A to 64C with timing shifted among the respective incoming lights LiA to LiC. Specifically, as illustrated in (a) of
Then, as illustrated in (a) of
Then, as illustrated in (a) of FIG. 6B8, at a time point tC when the outgoing light LeB emitted from the excitation light emitter 63B has sufficiently decayed, the incoming light LiC is made incident in a pulsed form onto the excitation light emitter 63C through the optical fiber 64C. At this time, as illustrated in (b) of
Consequently, even if the detection points PA to PC are arranged at positions where the respective outgoing lights LeA to LeC can interfere with each other, the outgoing lights LeA to LeC can be detected by the detection points PA to PC, without causing interference among the outgoing lights LeA to LeC. Thus, even where a plurality of temperature measurement points are present on the sensing wafer WS, it is possible to improve the temperature measurement accuracy, while preventing increase in the size of the viewport 25.
As illustrated in
An excitation light emitter 83 is arranged at the distal end of each passage 81. The excitation light emitter 83 may be configured as in the excitation light emitter 63 of
Here, as illustrated in
A reflecting mirror 86 is arranged at the distal end of the passage 82. In this case, the reflecting mirror 86 may be arranged at the central portion of the sensing wafer WS5. As illustrated in
Further, a plurality of collimation lenses 85 and a transmission window 87 are arranged in the passage 82. The collimation lenses 85 may be arranged below the reflecting mirror 86, and the transmission window 87 may be arranged below the collimation lenses 25. As the material of the transmission window 87, for example, AlN or AlON may he used.
Further, as illustrated in
At the central portion of the stage ST3, an opening K3 is formed to penetrate the stage ST3 in the thickness direction. The opening K3 is provided with a transmission window 68 on the front side. As the material of the transmission window 68, for example, AlN or AlON may be used.
A cylindrical body 73 is attached below the stage ST3. The distal end of the cylindrical body 73 may be fixed to the back side of the stage ST3. The cylindrical body 73 is provided with a transmission window 74 on the lateral side. Inside the cylindrical body 73, a half mirror 70, a light-filter 71, and a light detector 72 are provided. Outside the cylindrical body 73, a light source 69 and a temperature calculator 73 are provided. The single light source 69 and the single light detector 72 can be used for the plurality of outgoing lights Le in common.
The light source 69 generates an incoming light Li to be incident onto the excitation light emitters 83. The half mirror 70 reflects the incoming light Li, and transmits the outgoing lights Le. The light-filter 71 transmits a wavelength component of the outgoing lights Le, and attenuates the other wavelength components. The light detector 72 detects the outgoing lights Le. Here, the light detector 72 can simultaneously detect the plurality of outgoing lights Le. In order to simultaneously detect the plurality of outgoing lights Le, an image sensor, such as a CCD or CMOS sensor, may be used as the light detector 72. The temperature calculator 73 calculates the temperature of the sensing wafer WS5 on the basis of a temperature characteristic of the outgoing lights Le.
Next, an explanation will be given of a method of measuring a temperature during a plasma process inside the chamber by using the sensing wafer WS5.
With reference to
Then, during the plasma etching process, an incoming light Li is emitted from the light source 60. Then, the incoming light Li is transmitted through the transmission window 74 and reflected by the half mirror 70, and is then transmitted through the transmission windows 68 and 87 and the collimation lenses 85. Further, the incoming light Li is reflected by the reflecting mirror 86 in radial directions, and then comes into the plurality of optical fibers 84. The incoming light Li is guided by the plurality of optical fibers 84, and is incident onto the plurality of excitation light emitters 83.
At each excitation light emitter 83, an outgoing light Le is generated in response to the incidence of the incoming light Li, and comes into the corresponding optical fiber 84. The respective outgoing lights Le are guided by the optical fibers 84, and are reflected by the respective reflecting surfaces 86A of the reflecting mirror 86. Further, the plurality of outgoing lights Le are individually condensed by the plurality of collimation lenses 85, are then transmitted through the transmission windows 87 and 68, and go out from the back side of the stage ST3.
The plurality of outgoing lights Le going out from the back side of the stage ST3 are transmitted through the half mirror 70, and a desired wavelength component is extracted therefrom by the light-filter 71, and is incident onto the light detector 72, by which the plurality of outgoing lights Le are detected. The detection result obtained by the light detector 72 is sent to the temperature calculator 73. Upon reception of the detection result from the light detector 72, the temperature calculator 73 calculates the temperatures of a plurality of measurement points of the sensing wafer WS5 on the basis of a temperature characteristic of the plurality of outgoing lights Le.
Here, as the reflecting mirror 86 including the plurality of reflecting surfaces 86A is arranged at the central portion of the sensing wafer WS5, the incoming light Li can be made simultaneously incident onto the plurality of excitation light emitters 83 from the back side of the sensing wafer WS5, and the plurality of outgoing lights Le can be simultaneously emitted from the back side. Accordingly, the light source 69 and the light detector 72 can be used for the plurality of excitation light emitters 83 in common. This makes it possible to make the apparatus configuration more compact, as compared with a case where the light source 69 and the light detector 72 are provided with respect to each of the plurality of excitation light emitters 83.
As illustrated in
Then, as illustrated in
Then, as illustrated in
Then, as illustrated in
Here, when the lower wafer WL and the upper wafer WU are to be bonded to each other, a ceramic-based adhesive may be used, or wafer direct bonding may be used. By a method using the ceramic-based adhesive or wafer direct bonding, a heat resistance of 1,000° C. or more can be obtained. Where the wafer direct bonding is used, the bonding surfaces may be subjected to a plasma activation process before the bonding. By performing the plasma activation process before the wafer direct bonding, a sufficient bonding strength can be obtained by an anneal process of 200° C. to 300° C.
If the upper wafer WU is contaminated or the upper wafer WU is damaged by temperature measurement during a plasma process, the upper wafer WU can be peeled off the lower wafer WL. Then, a new upper wafer WU can be bonded to the lower wafer WL. At this time, the excitation light emitters 83, the optical fibers 84, the transmission window 87, the collimation lenses 85, and the reflecting mirror 86, which are arranged on the lower wafer WL, can be used again as they are. Consequently, it is possible to reduce the running cost for temperature measurement using the sensing wafer WS5.
As illustrated in
Then, as illustrated in
Then, as illustrated in
Then, as illustrated in
Then, as illustrated in
Here, in the case of the sensing wafer WS6, the plurality of waveguides 94 corresponding to the plurality of excitation light emitters 83 can be formed all together. Accordingly, even where the plurality of excitation light emitters 83 are provided in the sensing wafer WS6, it is possible to save the labor for arranging a plurality of optical fibers one by one on the wafer.
In the embodiments described above, an explanation has been given of a method of measuring a temperature by using a sensing wafer provided with an optical fiber and an optical system. A sensing wafer provided with an optical fiber and an optical system can be used for measurement other than the temperature measurement. In this case, the sensing wafer can detect a state inside the sensing wafer or outside the sensing wafer. The state outside the sensing wafer may be a state above the sensing wafer, or may be a state at a lateral side of the sensing wafer.
Next, an explanation will be given of a method of using a sensing wafer provided with an optical fiber and an optical system in measurement or monitoring other than the temperature measurement. The following description will take as an example a configuration in which a sensing wafer is provided with the passages 81 and 82, the optical fibers 84, the reflecting mirror 86, the collimation lenses 85, and the transmission window 87, as illustrated in
As illustrated in
An opening 101 is formed at the distal end of each passage 81 to open to the front side of the sensing wafer WS7. An opening 102 is formed on the passage 82 to open to the front side of the sensing wafer WS7. In each passage 81, an optical fiber 84 is provided to extend from the opening 101 to the passage 82. In the passage 82, a reflecting mirror 86, collimation lenses 85, and a transmission window 87 are arranged.
A reflecting mirror 104 is arranged at the bottom of each opening 101, and an objective lens 103A is arranged above the reflecting mirror 104. In place of the reflecting mirror 104, a prism may be used. In the opening 102, an objective lens 103B is arranged above the reflecting mirror 86.
Here, as illustrated in
Further, as illustrated in
A cylindrical body 73′ is attached below the stage ST3. The distal end of the cylindrical body 73′ may be fixed to the back side of the stage ST3. Inside the cylindrical body 73′, a fiber camera 105 is provided. The fiber camera 105 may include a light source for illuminating an observation object. Outside the cylindrical body 73′, a display 106 is provided.
Next, an explanation will be given of a method of observing an upper electrode 100 inside a chamber by using the sensing wafer WS7.
With reference to
Then, an illumination light L1 is emitted from the fiber camera 105. The illumination light L1 is transmitted through the transmission windows 68 and 87 and the collimation lenses 85. Further, the illumination light L1 is reflected by the reflecting mirror 86 in radial directions, then comes into the plurality of optical fibers 84, and is guided by the plurality of optical fibers 84. Further, a part of the illumination light L1 goes out upward from the reflecting mirror 86 through the optical fiber 88 of
When the upper electrode 100 is irradiated with the plurality of illumination lights L1, a plurality of reflection lights L1 are generated from the upper electrode 100. The reflection lights L2 are transmitted through the respective objective lenses 103A, and are reflected by the reflecting mirrors 104. Then, the plurality of reflection lights L2 come into the plurality of optical fibers 84, are guided by the plurality of optical fibers 84, and are then reflected by the respective reflecting surfaces 86A of the reflecting mirror 86. On the other hand, a reflection light L2 reflected from the central portion of the upper electrode 100 is transmitted through the objective lens 103B, and is guided by the optical fiber 88.
Further, all of these reflection lights L2 are transmitted through the collimation lenses 85 and the transmission windows 87 and 68, and go out from the back side of the stage ST3. The plurality of reflection lights L2 going out from the back side of the stage ST3 are incident onto the fiber camera 105, by which an image of the surface of the upper electrode 100 is generated on the basis of the reflection lights L2. The image generated by the fiber camera 105 is displayed by the display 106.
Here, by using the sensing wafer W57, it is possible to observe the surface state of the upper electrode 100, without dismounting the upper electrode 100 from the chamber, even where the distance between the stage ST3 and the upper electrode 100 is small.
As a result of observation on the surface state of the upper electrode 100, for example, if deposits attaching to the surface of the upper electrode 100 are found, the loading of a wafer W into the chamber can be stopped. Then, plasma cleaning is performed to the surface of the upper electrode 100 so that the deposits attaching to the surface of the upper electrode 100 can be removed. At this time, by increasing the gas flow rate at the places where the deposits attach, it is possible to efficiently remove the deposits attaching to the surface of the upper electrode 100.
In the system of
In the optical fiber distance meter 115, for example, halogen light may be used as an incoming light L3. The optical fiber distance meter 115 can acquire the distance to an object on the basis of a change in light amount of a reflection light L4 obtained by irradiating the object with the incoming light L3. The optical fiber distance meter 115 may include a probe for every measurement paint.
In this case, in the optical fiber distance meter 115, a probe PB1 may be used in which light emitting portions E1 and light receiving portions E2 are arranged at random as illustrated in
Here, as illustrated in
Next, an explanation will be given of a method of measuring the distance to an upper electrode 100 inside a chamber by using the sensing wafer WS7.
With reference to
Then, an incoming light L3 is emitted from the optical fiber distance meter 115. The incoming light L3 is transmitted through the transmission windows 68 and 87 and the collimation lenses 85. Further, the incoming light L3 is reflected by the reflecting mirror 86 in radial directions, then comes into the plurality of optical fibers 84, and is guided by the plurality of optical fibers 84. Further, a part of the incoming light L3 goes out upward from the reflecting mirror 86 through the optical fiber 88 of
When the plurality of incoming lights L3 are incident onto the upper electrode 100, a plurality of reflection lights L4 are generated from the upper electrode 100. The reflection lights L4 are transmitted through the respective objective lenses 103A, and are reflected by the reflecting mirrors 104. Then, the plurality of reflection lights L4 come into the plurality of optical fibers 84, are guided by the plurality of optical fibers 84, and are then reflected by the respective reflecting surfaces 86A of the reflecting mirror 86. On the other hand, a reflection light L4 reflected from the central portion of the upper electrode 100 is transmitted through the objective lens 103B, and is guided by the optical fiber 88.
Further, all of these reflection lights L4 are transmitted through the collimation lenses 85 and the transmission windows 87 and 68, and go out from the back side of the stage ST3. The plurality of reflection lights L4 going out from the back side of the stage ST3 are incident onto the optical fiber distance meter 115, by which the distances from the sensing wafer WS7 to the upper electrode 100 are calculated on the basis of the light amounts of the reflection lights L4 at respective measurement points. The distances to the upper electrode 100 calculated by the optical fiber distance meter 115 are displayed by the display 106.
Here, by using the sensing wafer WS7, it is possible to place the sensing wafer WS7 on the stage ST3, without moving the upper electrode 100, even where the distance between the stage ST3 and the upper electrode 100 is small. Accordingly, it is possible to estimate, with high accuracy, the distance from a wafer W to the upper electrode 100 set in a plasma process performed inside the chamber.
As a result of calculation on the distances from the sensing wafer WS7 to the upper electrode 100, if the distances from the respective measurement points of the sensing wafer WS7 to the upper electrode 100 are not uniform, the loading of a wafer W into the chamber can be stopped. Then, for example, the inclination of the upper electrode 100 is adjusted so that the distances from the respective measurement points of the sensing wafer WS7 to the upper electrode 100 can become uniform. Accordingly, it is possible to reduce the dimensional unevenness among devices to be formed on a wafer W transferred into the chamber thereafter, and thus to improve the quality of the devices to be formed on the wafer W.
In the system of
In the system of
Next, an explanation will be given of a methodof measuring the planar light emitting distribution of plasma PZ inside the chamber by using the sensing wafer WS7.
With reference to
Then, plasma lights L5 are emitted by the plasma PZ during a plasma etching process. The plasma lights L5 are transmitted through the respective objective lenses 103A, and are reflected by the reflecting mirrors 104. The plasma lights L5 are light including a bright line spectrum inherent to an element, whichis emitted in accordance with the excitation state of the plasma PZ. Then, the plurality of plasma lights 15 come into the plurality of optical fibers 84, are guided by the plurality of optical fibers 84, and are then reflected by the respective reflecting surfaces 86A of the reflecting mirror 86. On the other hand, a plasma light L5 emitted from the central portion of the plasma PZ is transmitted through the objective lens 103B, and is guided by the optical fiber 88 of
Further, all of these plasma lights L5 are transmitted through the collimation lenses 85 and the transmission windows 87 and 68, and go out from the back side of the stage ST4. The plurality of plasma lights L5 going out from the back side of the stage ST4 are incident onto the emission spectrometer 125, by which the planar intensity distribution of the plasma lights L5 is detected. The planar intensity distribution detected by the emission spectrometer 125 is displayed by the display 106.
Here, by using the sensing wafer WS7, it is possible to detect the planar intensity distribution of the plasma lights L5 during a plasma etching process. Accordingly, it is possible to calculate the planar intensity distribution of the plasma lights L5 with accuracy equivalent to that obtained when the plasma process is performed to a wafer W for forming devices inside the chamber.
As a result of calculation on the planar intensity distribution of the plasma lights L5, if the planar intensity distribution of the plasma lights L5 is not uniform, the process to a wafer W under this condition inside the chamber can be stopped. Then, for example, the temperature of the heaters 126 is controlled to change the temperature distribution of the stage ST4 in accordance with the planar intensity distribution of the plasma lights L5. Thus, the non-uniformity in the planar intensity distribution of the plasma lights L5 can be corrected, whereby the processing dimensions can be made uniform. Accordingly, it is possible to perform the process to the wafer W under optimized process conditions, to reduce the dimensional unevenness among devices to be formed on the wafer W, and thus to improve the quality of the devices to be formed on the wafer W.
Here, in order to uniformize the planar intensity distribution of the plasma lights L5, the flow rate distribution of the G1 may be varied in accordance with the planar intensity distribution of the plasma lights L5.
As illustrated in
Here, as illustrated in
Further, as illustrated in
The light source 129 generates an incoming light L6 to come into the optical fibers 84. As the incoming light L6, laser light may be used. The half mirror 130 reflects the incoming light L6, and transmits the Raman scattering lights L7. The filter 131 transmits a frequency component of the Raman scattering lights L7, and attenuates the other frequency components. The spectroscope 134 spectrally disperses the Raman scattering lights L7. The light detector 132 detects the Raman scattering lights L7. Here, the light detector 132 can simultaneously detect the plurality of Raman scattering lights L7. The stress calculator 133 calculates the stress of the sensing wafer WS8 on the basis of the Raman shift amounts of the Raman scattering lights L7.
Next, an explanation will be given of a method of measuring a stress during a plasma process inside the chamber by using the sensing wafer WS8.
With reference to
Then, during the plasma etching process, an incoming light L6 is emitted from the light source 129 Then, the incoming light L6 is transmitted through the transmission window 74, is reflected by the half mirror 130, and is then transmitted through the transmission windows 68 and 87 and the collimation lenses 85. Further, the incoming light L6 is reflected by the reflecting mirror 86 in radial directions, and then comes into the plurality of optical fibers 84. The incoming light L6 is guided by the plurality of optical fibers 84, and is incident onto the wafer substrate of the sensing wafer WS8. Further, a part of the incoming light L6 is incident onto the central portion of the wafer substrate of the sensing wafer WS8 through the optical fiber 88.
Raman scattering lights L7 are emitted from the wafer substrate of the sensing wafer WS8, in response to the incidence of the incoming light L6, and come into the optical fibers 84. The respective Raman scattering lights L7 are guided by the optical fibers 84, and are reflected by the respective reflecting surfaces 86A of the reflecting mirror 86. On the other hand, a Raman scattering light L7 emitted from the central portion of the wafer substrate of the sensing wafer WS8 is guided by the optical fiber 88.
Further, all of these Raman scattering lights L7 are condensed by the collimation lenses 85, are then transmitted through the transmission windows 87 and 68, and go out from the back side of the stage ST3. The plurality of Raman scattering lights L7 going out from the back side of the stage ST3 are transmitted through the half mirror 130, and a desired wavelength band component is extracted therefrom by the filter 131, and is spectrally dispersed for every specific wavelength component by the spectroscope 134.
The Raman scattering lights L7 spectrally dispersed for every specific wavelength component are incident onto the light detector 72, by which the specific wavelength components of the Raman scattering lights L7 are detected. The detection result obtained by the light detector 132 is sent to the stress calculator 133. Upon reception of the detection result from the light detector 132, the stress calculator 133 calculates the stress distribution of the sensing wafer WS8 on the basis of the Raman shifts of the specific wavelength component the Raman scattering lights L7.
As illustrated in
As the lattice interval the substrate crystal becomes larger because of a tensile stress acting on the substrate crystal, the bonding force of the substrate crystal decreases, and the vibration frequency of the lattice vibration becomes lower. Accordingly, a Raman scattering light L7′ is emitted to have a peak shifted on the lower frequency side as compared with the Raman scattering light L7.
On the other hand, as the lattice interval the substrate crystal becomes smaller because of a compressive stress acting on the substrate crystal, the bonding force of the substrate crystal increases, and the vibration frequency of the lattice vibration becomes higher. Accordingly, a Raman scattering light. L7″ is emitted to have a peak shifted on the higher frequency side as compared with the Raman scattering light L7.
Here, by using the sensing wafer WS8, it is possible to detect the stress distribution of the sensing wafer WS8 during the plasma etching process. Accordingly, it is possible to calculate the stress distribution with accuracy equivalent to that obtained when the plasma process is performed to a wafer W for forming devices inside the chamber.
As a result of calculation on the stress distribution of the sensing wafer WS8, if the stress distribution of the sensing wafer W38 is not uniform, the process to a wafer W under this condition inside the chamber can be stopped. Then, for example, the flow rate distribution of the gas G1 is varied in accordance with the stress distribution of the sensing wafer WS8, whereby the stress distribution of the sensing wafer WS8 can be made uniform. Accordingly, it is possible to perform the process to the wafer W under optimized process conditions, to reduce the dimensional unevenness among devices to be formed on the wafer W, and thus to improve the quality of the devices to be formed on the wafer W.
As illustrated in
A sensing wafer WS9 can be placed on the stage ST5. The stage ST5 includes through holes 111 formed therein. The through holes 111 may penetrate the pedestal 112 and the electrostatic chuck 113 in the vertical direction. Each through hole 111 is provided with a pin 110 inside. The pin 110 can be moved up and down. In this case, the sensing wafer WS9 can be moved up and down by moving the pins 110 up and down, when the sensing wafer W59 is to be transferred.
An optical fiber 114 is inserted in each pin 110. Each pin 110 may include a hollow 110A in which the optical fiber 114 is inserted. The hollow 110A may be formed to extend from the proircial end of the pin 110 to its distal end. The optical fiber 114 can cause an incoming light Li emitted from below the stage ST5 to come in from the back side of the sensing wafer WS9, and cause an outgoing light Le emitted from the back side of the sensing wafer WS9 to go out downward from the stage ST5. A collimation lens 116 is provided at the distal end of each pin 110. Below the stage ST5, sets of a light source 29, a half mirror 30, a light-filter 31, and a light detector 32 are provided.
On the other hand, excitation light emitters 43 are embedded in the sensing wafer WS9. As illustrated in
Passages 142 are formed in the sensing wafer WS9 to correspond to the arrangement positions of the respective pins 110. The passages 142 may be formed in the vertical direction from the back side of the sensing wafer WS9. The passages 142 may be formed not to penetrate the front side of the sensing wafer WS9. A reflecting mirror 146 is arranged at the distal end of each passage 142. The reflecting mirror 146 may be provided by mirror-finishing the distal end of each passage 142, or may be provided by setting a reflecting surface at the distal end of each passage 142. The reflecting mirror 146 may be made of the same material as the wafer substrate of the sensing wafer WS9, or may be made of a different material from the wafer substrate of the sensing wafer WS9.
Passages 141 are formed below the front side of the sensing wafer WS9. The passages 141 may be formed to extend from the respective excitation light emitters 143 toward the passages 142. In each passage 141, an optical fiber 144 is provided to extend from the corresponding excitation light emitter 143 to the corresponding passage 142. The distal end of each passage 142 may be coupled with the proximal end of the corresponding passage 111. A collimation lens 145 is arranged at the proximal end of each passage 141. The collimation lens 145 may be arranged in the light reflecting direction of the corresponding reflecting mirror 146.
Here, as illustrated in
Next, an explanation will be given of a method of measuring a temperature during a plasma process inside the chamber by using the sensing wafer WS9.
With reference to
When the temperature of the sensing wafer WS9 is to be measured during a plasma etching process, the distal ends of the pins 110 may be separated from the sensing wafer WS9. At this time, as illustrated in
Then, an incoming light Li is emitted from each light source 29. The incoming light Li is reflected by the corresponding half mirror 30, and then comes into the corresponding optical fiber 114. The incoming light Li is guided by this optical fiber 114 in the vertical direction, is then condensed by the corresponding collimation lens 116, and is reflected by the corresponding reflecting mirror 146 to change the traveling direction of the incoming light Li into the horizontal direction. Then, the incoming light Li is condensed by the corresponding collimation lens 145, and comes into the corresponding optical fiber 144. Then, the incoming light Li is guided by this optical fiber 144 in the horizontal direction, and is incident onto the corresponding excitation light emitter 143.
At each excitation light emitter 143, an outgoing light Le is generated in response to the incidence of the corresponding incoming light Li, and comes into the corresponding optical fiber 144. The outgoing light Le is guided by this optical fiber 144 in the horizontal direction, passes through the corresponding collimation lens 145, and is then reflected by the corresponding reflecting mirror 146 to change the traveling direction of the outgoing light Le into the vertical direction. Further, the outgoing light Le passes through the corresponding collimation lens 116, then comes into the corresponding optical fiber 114, and is guided by this optical fiber 114 in the vertical direction. Further, the outgoing light Le is transmitted through the corresponding half mirror 30, and a desired wavelength component is extracted therefrom by the light-filter 31, and is incident onto the corresponding light detector 32, by which the outgoing light Le is detected. Upon detection of the outgoing light Le, the temperature of the sensing wafer WS9 is calculated on the basis of a temperature characteristic of the outgoing light Le.
Here, as the optical fiber 114 is provided in each pin 110 to cause the incoming light Li to come in from the back side of the sensing wafer WS9, and to cause the outgoing light Le to go out from the back side of the sensing wafer WS9, each through hole 111 for moving the pin 110 up and down can be used as a passage for the incoming light Li and outgoing light Le. Accordingly, in order to provide the passage for the incoming light Li and outgoing light Le, there is no need to perform a drilling process to the stage ST5, other than processes for the through holes 111. This makes it possible to reduce the man hour necessary for performing drilling processes to the stage ST5.
Here, the stage ST5 and the pins 110 may be used in place of the stage ST3 and the sensing wafer WS7 illustrated in
In the plasma processing apparatus of
An optical fiber 114 is inserted in each pin 110′. Each pin 110′ may include a hollow 110A′ in which the optical fiber 114 is inserted. The hollow 110A′ may be formed not to penetrate the distal end of the pin 110′. In each pin 110′, a reflecting mirror 146′ is arranged at the distal end of the hollow 110A′. A collimation lens 116′ is provided on the lateral side of each pin 110′. The collimation lens 116′ may be arranged between the reflecting mirror 146′ and the distal end of the optical fiber 114.
The sensing wafer WS10 includes passages 142′ formed therein in place of the passages 142 and reflecting mirrors 146 of the sensing wafer WS9. The passages 142′ may be formed in the vertical direction from the back side of the sensing wafer WS10. The passages 142′ may be formed not to penetrate the front side of the sensing wafer WS10. Each pin 110′ can be inserted into the corresponding passage 142′ from the back side of the sensing wafer WS10.
Next, an explanation will be given of a method of measuring a temperature during a plasma process inside the chamber by using the sensing wafer WS10.
With reference to
After the sensing wafer WS10 is placed on the pins 110′, the pins 110′ are moved down, and the sensing wafer WS10 is thereby placed onto the electrostatic chuck 113. Then, the sensing wafer WS10 is attracted by the electrostatic chuck 113, and thus the sensing wafer WS10 is fixed on the electrostatic chuck 113.
When the temperature of the sensing wafer WS10 is to be measured during a plasma etching process, the distal ends of the pins 110′ may be separated from the sensing wafer WS10. At this time, as illustrated in
Then, an incoming light Li is emitted from each light source 29. The incoming light Li is reflected by the corresponding half mirror 30, and then comes into the corresponding optical fiber 114. The incoming light Li is guided by this optical fiber 114 in the vertical direction, and is then reflected by the corresponding reflecting mirror 146′ to change the traveling direction cf the incoming light Li into the horizontal direction. Thus, the incoming light passes through the corresponding collimation len 116′. Then, the incoming light Li is condensed by the corresponding collimation lens 145, and comes into the corresponding optical fiber 144. Then, the incoming light Li is guided by this optical fiber 144 in the horizontal direction, and is incident onto the corresponding excitation light emitter 143.
At each excitation light emitter 143, an outgoing light Le is generated in response to the incidence of the corresponding incoming light Li, and comes into the corresponding optical fiber 144. The outgoing light Le is guided by this optical fiber 144 in the horizontal direction, passes through the corresponding collimation lens 145, and is then condensed by the corresponding collimation lens 116′. Then, the outgoing light Le is reflected by the corresponding reflecting mirror 146′ to change the traveling direction of the outgoing light Le into the vertical direction. Further, the outgoing light Le comes into the corresponding optical fiber 114, is guided by this optical fiber 114 in the vertical direction, and is then transmitted through the corresponding half mirror 30. Then, a desired wavelength component is extracted from the outgoing light Le by the light-filter 31, and is incident onto the corresponding light detector 32, by which the outgoing light Le is detected. Upon detection of the outgoing light Le, the temperature of the sensing, wafer WS10 is calculated on the basis of a temperature characteristic of the outgoing light Le.
Here, as the optical fiber 114 is provided in each pin 110′ to cause the incoming light Li to come in from the back side of the sensing wafer WS10, and to cause the outgoing light Le to go out from the back side of the sensing wafer WS10, each through hole 111 for moving the pin 110′ up and down can be used as a passage for the incoming light Li and outgoing light Le. Accordingly, in order to provide the passage for the incoming light Li and outgoing light Le, there is no need to perform a drilling process to the stage ST5, other than processes for the through holes 111. This makes it possible to reduce the man hour necessary for performing drilling processes to the stage ST5.
In the plasma processing apparatus of
Further, in the plasma processing apparatus of
An optical fiber 161 is inserted in each pin Each pin 162 may include a hollow 162A in which the optical fiber 161 is inserted. The hollow 162A may be formed not to penetrate the distal end of the pin 162. In each pin 162, a reflecting mirror 163 is arranged at the distalend of the hollow 162A. A light-condensing lens 164 is provided on the lateral side of each pin 162. The light-condensing lens 164 may be arranged between the reflecting mirror 163 and the distal end of the optical fiber 161.
Next, an explanation will be given of a method of observing the wear-out state of the focus ring 152 by using the bins 162.
With reference to
When the inner peripheral surface of the focus ring 152 is irradiated with the illumination light L9, a reflection light L10 is generated from the inner peripheral surface of the focus ring 152. The reflection light L10 passes through the light-condensing lens 164, and is reflected by the reflecting mirror 163 to change the traveling direction of the reflection light L10 into the vertical direction. Then, the reflection light L10 comes into the corresponding optical fiber 161, and is guided by this optical fiber 161 in the vertical direction. Then, the reflection light L10 is incident onto the corresponding fiber camera 153, by which an image of the inner peripheral surface of the focus ring 152 is generated on the basis of the reflection light L10.
The image of the inner peripheral surface of the focus ring 152 can be used to determine the wear-out state of the focus ring 152 When it is determined that the wear-out of the focus ring 152 is serious, the focus ring 152 can be replaced.
Here, as the pins 162 are used to observe the inner peripheral surface of the focus ring 152, it is possible to determine the wear-out state of the focus ring 152 without opening the chamber of the plasma processing apparatus to the atmosphere.
Further, as the optical fiber 161 is provided in each pin 162 to irradiate the inner peripheral surface of the focus ring 152 with the illumination light L9, each through hole 111 for moving the pin 162 up and down can be used as a passage for the illumination light L9 and reflection light L10. Accordingly, in order to provide the passage for the illumination light L9 and reflection light. L10, there is no need to perform a drilling process to the stage ST5, other than processes for the through holes 111. This makes it possible to reduce the man hour necessary for performing drilling processes to the stage ST5.
As illustrated in (1) of
Here, as the inclination of the inner peripheral surface of the focus ring 152 is larger, the light intensity of the reflection light L10 becomes lower. Accordingly, as illustrated in (2) of
As a result, by detecting the brightness of the inner peripheral surface of the focus ring 152 under observation, it is possible to determine the wear-out degree of the focus ring 152 with respect to its height. For example, it is assumed that the height of the focus ring 152 is h1. In this case, as illustrated in (2) of
On the other hand, as illustrated in (2)
Here, in order to improve the measurement accuracy of the wear-out state of the focus ring 152, it may be adopted to alternately repeat a step of moving the pins 162 by a certain distance in the vertical direction, in a state where the pins 162 are projected upward from the electrostatic chuck 113, and a step of observing the inner peripheral surface of the focus ring 152. For example, the pins 162 are projected to align the central position of each light-condensing lens 164 with the height hl, and then the inner peripheral surface of the focus ring 152 is observed. Then, the pins 162 are projected to align the central position of each light-condensing lens 164 with the height h2, and then the inner peripheral surface of the focus ring 152 is observed. Then, the pins 162 are projected to align the central position of each light-condensing lens 164 with the height h3, and then the inner peripheral surface of the focus ring 152 is observed. Then, these observation results can be used to determine the wear-out state of the focus ring 152.
In
As illustrated in (1) of
In this case, as illustrated in (2) of
Here, it is assumed that the light intensity at the height hi before wear-out of the focus ring is L0. In this case, as illustrated in
As a result, by observing the inner peripheral surface of the focus ring 152 to check the light intensity with respect to the height of the focus ring 152, it is possible to determine the height of the focus ring 152 down to which its wear-out has progressed. Then, it is possible to determine the replacement timing of the focus ring 152, by determining whether the height of the focus ring 152 down to which its wear-out has progressed reaches a predetermined value.
As illustrated in
Here, the distances in the height direction from the distal ends of the pins 182A to 182C to the reflecting mirrors 183A to 183C may be set different from each other. Along with this, the distances in the height direction from the distal ends of the pins 182A to 182C to the light-condensing lenses 184A to 184C may be set different from each other.
In this case, even when the pins 182A to 182C are projected upward from the stage ST5 to the same height, the pins 182A to 182C can have observation positions to the focus ring 152 different from each other in the height direction. For example, the observation positions may be set at an upper portion of the focus ring 152 by the pin 182A, at an intermediate portion of the focus ring 152 by the pin 182B, and at a lower portion of the focus ring 152 by the pin 182C.
Consequently, it is possible to improve the observation resolution on the focus ring 152, and thus to improve the determination accuracy about the wear-out state of the focus ring 152.
In the plasma processing apparatus of
In the sensing wafer WS11, in place of the passages 141 and optical fibers 144 of the sensing wafer WS10, passages 141′ and optical fibers 144′ are provided. The passages 141′ may be formed to extend from the respective pins 110′ toward end portions of the sensing wafer WS11 in the horizontal direction. The passage 141′ may be formed to open to the end portions of the sensing wafer WS11. A collimation lens 145 is arranged at the proximal end of each passage 141′. In each passage 141′, an optical fiber 144′ is provided to extend from the collimation lens 145 to the corresponding end portion of the sensing wafer WS11.
Next, an explanation will be given of a method of observing the wear-out state of the focus ring 152 by using the sensing wafer WS11.
With reference to
Then, when the wear-out state of the focus ring 152 is to be observed, the pins 110′ are moved up and projected upward from the electrostatic chuck 113. At this time, as illustrated in
Then, an illumination light L9 is emitted from each fiber camera 153. The illumination light L9 comes into the corresponding optical fiber 114, is guided by this optical fiber 114 in the vertical direction, and is then reflected by the corresponding reflecting mirror 146′ to change the traveling direction of the illumination light L9 into the horizontal direction. Then, the illumination light L9 is condensed by the corresponding collimation lenses 116′ and 145, is guided by the corresponding optical fiber 144′ in the horizontal direction, and irradiates the inner peripheral surface of the focus ring 152.
When the inner peripheral surface of the focus ring 152 is irradiated with the illumination light L9, a reflection light L10 is generated from the inner peripheral surface of the focus ring 152. The reflection light L10 is guided by the corresponding optical fiber 144′ in the horizontal direction, is then condensed by the corresponding collimation lenses 116′ and 145, and is reflected by the corresponding reflecting mirror 146′ to change the traveling direction of the reflection light L10 into the vertical direction. Then, the reflection light L10 comes into the corresponding optical fiber 114, and is guided by this optical fiber 114 in the vertical direction. Then, the reflection light L10 is incident onto the corresponding fiber camera 153, by which an image of the inner peripheral surface of the focus ring 152 is generated on the basis of the reflection light L10.
The image of the inner peripheral surface of the focus ring 152 can be used to determine the wear-out state of the focus ring 152. When it is determined that the wear-out of the focus ring 152 is serious, the focus ring 152 can be replaced.
Here, as the sensing wafer WS11 is used to cause the illumination light L9 and the reflection light L10 to travel in the horizontal direction, it is possible to prevent light from the outside from mixing into the illumination light L9 and the reflection light L10. Accordingly, as compared with the method of
In the plasma processing apparatus of
In the pins 110″, the optical fibers 114 inserted in the pins 110′ are omitted. In the sensing wafer WS12, the collimation lenses 145 of the sensing wafer WS11 are omitted. In each passage 141′, an optical fiber 144″ is provided to extend from the corresponding passage 142′ to an end portion of the sensing wafer WS12.
Next, an explanation will be given of a method of observing the wear-out state of the focus ring 152 by using the sensing wafer WS12.
With reference to
Then, when the wear-out state of the focus ring 152 is to be observed, the pins 110″ are moved up and projected upward from the electrostatic chuck 113. At this time, as illustrated in
Then, an illumination light L9 emitted from each fiber camera 153. The illumination light L9 travels through the corresponding hollow 110A′ in the vertical direction, and comes into the back side of the sensing wafer WS12. Then, the illumination light L9 is reflected by the corresponding reflecting mirror 146′ to change the traveling direction of the illumination light L9 into the horizontal direction. Then, the illumination light L9 is condensed by the corresponding collimation lens 116′, is guided by the corresponding optical fiber 144′ in the horizontal direction, and irradiates the inner peripheral surface of the focus ring 152.
When the inner peripheral surface of the focus ring 152 is irradiated with the illumination light L9, a reflection light L10 is generated from the inner peripheral surface of the focus ring 152. The reflection light L10 is guided by the corresponding optical fiber 144′ in the horizontal direction, is turned into parallel light by the corresponding collimation lens 116′, and is reflected by the corresponding reflecting mirror 146′ to change the traveling direction of the reflection light L10 into the vertical direction. Then, the reflection light L10 travels through the corresponding hollow 110A′ in the vertical direction, and is incident onto the corresponding fiber camera 153, by which an image of the inner peripheral surface of the focus ring 152 is generated on the basis of the reflection light L10.
The image of the inner peripheral surface of the focus ring 152 can be used to determine the wear-out state of the focus ring 152. When it is determined that the wear-out of the focus ring 152 is serious, the focus ring 152 can be replaced.
Here, as the sensing wafer 12 is used to cause the illumination light L9 and the reflection light L10 to travel in the horizontal direction, it is possible to prevent light from the outside from mixing into the illumination light L9 and the reflection light L10. Accordingly, as compared with the method of
Here, in the embodiments described above, an explanation has been given of a method in which the illumination light emitted from each fiber camera is caused to come into the back side of the sensing wafer by using the hollow inside the corresponding pin. In this respect, however, the pins may be set retreated outside the through holes of the stage. In this case, the illumination light emitted from each fiber camera can be guided into the back side of the sensing wafer directly through the corresponding through hole by using, for example, an optical fiber inserted into the through hole of the stage.
Further, in embodiments described above, an explanation has been given of a method in which a pin for moving a wafer up and down or a through hole for inserting the pin is used to cause light to come into back side of a sensing wafer. In this respect, however, a through hole other than the through hole for inserting the pin for moving a wafer up and down may be used to insert therein an optical fiber. For example, a through hole formed in the electrostatic chuck to supply a heat transfer medium to the back side of a wafer may be used to insert therein an optical fiber for transferring an illumination light and/or a reflection light between the fiber camera and the focus ring.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2017-046030 | Mar 2017 | JP | national |