Substrate processing apparatus and irradiation position adjusting method

A substrate processing apparatus includes a placing table, having a first placing surface on which a substrate is placed and a rear surface opposite to the first placing surface, provided with a first window which allows the first placing surface and the rear surface to communicate with each other and which is configured to transmit light; a first adjusting device configured to hold a first light irradiation unit configured to irradiate light toward the first window and configured to adjust an irradiation position of the light on the rear surface; and a first reflection member, having retroreflection property, disposed at the rear surface of the placing table to enclose the first window, and configured to reflect a part of the light and return reflection light indicating a deviation between the irradiation position of the light and a position of the first window to the first light irradiation unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2019-092785 filed on May 16, 2019, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The various aspects and embodiments described herein pertain generally to a substrate processing apparatus and an irradiation position adjusting method.

BACKGROUND

Patent Document 1 proposes a technique of measuring a temperature of a substrate. In this technique, light is irradiated from a light irradiation unit toward a window which is formed at a placing table on which the substrate is placed and is capable of transmitting the light, and the temperature of the substrate is measured based on an interference state of reflection light returning to the light irradiation unit after being reflected on the substrate.

SUMMARY

In one exemplary embodiment, a substrate processing apparatus includes a placing table, having a first placing surface on which a substrate is placed and a rear surface opposite to the first placing surface, provided with a first window which allows the first placing surface and the rear surface to communicate with each other and which is configured to transmit light; a first adjusting device configured to hold a first light irradiation unit configured to irradiate light for state measurement of the substrate toward the first window and configured to adjust an irradiation position of the light irradiated from the first light irradiation unit on the rear surface of the placing table; and a first reflection member, having retroreflection property, disposed at the rear surface of the placing table to enclose the first window, and configured to reflect a part of the light irradiated from the first light irradiation unit and return reflection light indicating a deviation between the irradiation position of the light and a position of the first window to the first light irradiation unit.

DETAILED DESCRIPTION

Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In the various drawings, same or corresponding parts will be assigned same reference numerals.

When light for temperature measurement of a substrate is irradiated toward a window which is formed at a placing table, it is important that an irradiation position of the light coincides with a position of the window. However, the irradiation position of the light and the position of the window formed at the placing table may not necessarily be coincident. For example, if the position of the window is deviated from an initial position when maintenance of the placing table is performed, there is a likelihood that the irradiation position of the light and the position of the window may be deviated from each other. Further, when the placing table experiences thermal expansion or thermal contraction, the position of the light and the position of the window may not be coincident as the position of the window may be deviated from the initial position.

If the light for the temperature measurement of the substrate is irradiated toward the window from a light irradiation unit in the state that the irradiation position of the light and the position of the window are deviated, reflection light which returns to the light irradiation unit by being reflected on the substrate may not be obtained, so it is difficult to perform the temperature measurement of the substrate based on an interference state of the reflection light. To solve the problem, it is considered to adjust the irradiation position of the light so that the irradiation position of the light is coincident with the position of the window. By way of example, there may be considered a method of scanning the irradiation position of the light from the light irradiation unit at the entire surface of the placing table facing the light irradiation unit to thereby search for a position of the window where an intensity of the reflection light is maximized, and adjusting the irradiation position of the light toward the found position of the window.

In this adjusting method, however, since the irradiation position of the light from the light irradiation unit needs to be scanned at the entire surface of the placing table facing the light irradiation unit, it takes time to carry out the adjustment of the irradiation position of the light. Thus, there is a demand for a technique capable of shortening the time taken for the adjustment of the irradiation position of the light.

[Configuration of Plasma Processing Apparatus]

First, a substrate processing apparatus according to an exemplary embodiment will be explained. In the exemplary embodiment, a plasma processing apparatus configured to perform a plasma processing on a semiconductor substrate (hereinafter, simply referred to as “wafer”) as a processing target will be described as an example of the substrate processing apparatus.

FIG.1is a diagram illustrating an example configuration of a plasma processing apparatus100according to the exemplary embodiment. The plasma processing apparatus100shown inFIG.1is configured as a parallel plate type plasma processing apparatus.

The plasma processing apparatus100is equipped with a processing vessel102having a cylindrical shape and made of, by way of non-limiting example, aluminum having an anodically oxidized (alumite-treated) surface. The processing vessel102is grounded. A substantially columnar placing table110for placing the wafer W thereon is provided at a bottom102aof the processing vessel102. The placing table110is equipped with a susceptor114which constitutes a lower electrode. The susceptor114is supported by a plate-shaped insulating member112made of ceramic or the like. A space113maintained in an atmospheric atmosphere is provided between the susceptor114and the bottom102aof the processing vessel102.

The placing table110is equipped with a susceptor temperature controller117which is capable of adjusting a temperature of the susceptor114to a required temperature. The susceptor temperature controller117is configured to circulate a temperature control medium into, for example, a temperature control medium path118provided within the susceptor114.

The susceptor114has a substrate placing portion115of a protruding shape formed at an upper central portion thereof to place the wafer W thereon; and a peripheral portion116provided at a peripheral side of the substrate placing portion115and having a top surface lower than the substrate placing portion115. A top surface of the substrate placing portion115serves as a substrate placing surface115aon which the wafer W is placed, and the top surface of the peripheral portion116serves as a focus ring placing surface116aon which a focus ring FR is placed. As illustrated inFIG.2, if an electrostatic chuck120is provided at an upper portion of the substrate placing portion115, a top surface of this electrostatic chuck120serves as the substrate placing surface115a. In the following, the substrate placing portion115and the electrostatic chuck120together will be appropriately referred to as “substrate placing portion115.” The electrostatic chuck120has a structure in which an electrode122is embedded in an insulator. A DC voltage of, e.g., 1.5 kV is applied to the electrostatic chuck120from a non-illustrated DC power supply which is connected to the electrode122. As a result, the wafer W is electrostatically attracted to the electrostatic chuck120. The substrate placing portion115has a diameter smaller than a diameter of the wafer W, so that a peripheral portion of the wafer W is protruded from the substrate placing portion115when the wafer W is placed thereon.

The focus ring FR is disposed at an upper peripheral portion of the susceptor114to surround the wafer W placed on the substrate placing surface115aof the electrostatic chuck120. The focus ring FR is placed on the focus ring placing surface116aof the peripheral portion116such that an inner side surface of the focus ring FR surrounds an outer side surface of the substrate placing portion115. The focus ring FR is an example of a ring member.

A gas passage is formed in the insulator112, the susceptor114and the electrostatic chuck120, and a heat transfer medium (for example, a backside gas such as a He gas) is supplied through this gas passage to a rear surface of the wafer W which is placed on the substrate placing surface115a. Heat is transferred between the susceptor114and the wafer W through this heat transfer medium, so that the wafer W is maintained at a preset temperature.

The placing table110is provided with a first window124extending from below the substrate placing portion115up to the substrate placing surface115a. The first window124is a transmission window configured to transmit light toward the wafer W placed on the substrate placing surface115a. Further, a first light irradiation unit172configured to irradiate light for temperature measurement of the wafer W toward the first window124is provided at the bottom102aof the processing vessel102, corresponding to the position of the first window124. The first light irradiation unit172is held by a first adjusting device174and fixed by the first adjusting device174to a position of a through hole formed at the bottom102a, corresponding to the position of the first window124. An irradiation position of the light irradiated toward the first window124from the first light irradiation unit172is adjusted by the first adjusting device174. Details of the first light irradiation unit172and the first adjusting device174will be elaborated later.

Further, the placing table110is also provided with a second window126extending from below the peripheral portion116up to the focus ring placing surface116a. The second window126is a transmission window configured to transmit light toward the focus ring FR placed on the focus ring placing surface116a. Further, a second light irradiation unit182configured to irradiate light for temperature measurement of the focus ring FR toward the second window126is provided at the bottom102aof the processing vessel102, corresponding to the position of the second window126. The second light irradiation unit182is held by a second adjusting device184and fixed by the second adjusting device184to a position of a through hole formed at the bottom102ato correspond to the position of the second window126. An irradiation position of the light irradiated toward the second window126from the second light irradiation unit182is adjusted by the second adjusting device184. Details of the second light irradiating unit182and the second adjusting device184will be elaborated later.

An upper electrode130is disposed above the susceptor114, facing the susceptor114. A space formed between this upper electrode130and the susceptor114is a plasma generation space. The upper electrode130is supported at an upper portion of the processing vessel102with an insulating shield member131therebetween.

The upper electrode130mainly includes an electrode plate132; and an electrode supporting body134configured to support the electrode plate132in a detachable manner. The electrode plate132is made of, by way of non-limiting example, quartz, and the electrode supporting body134is made of a conductive material such as, but not limited to, aluminum having an alumite-treated surface.

The electrode supporting body134is provided with a processing gas supply140configured to introduce a processing gas from a processing gas source142into the processing vessel102. The processing gas source142is connected to a gas inlet opening143of the electrode supporting body134via a gas supply line144.

The gas supply line144is provided with a mass flow controller (MFC)146and an opening/closing valve148in sequence from the upstream side, as illustrated inFIG.1, for example. Here, a flow control system (FCS) may be provided instead of the MFC. A fluorocarbon gas (CxFy) such as, but not limited to, a C4F8gas is supplied from the processing gas source142as the processing gas for etching.

The processing gas source142is configured to supply, for example, an etching gas for plasma etching. Further, though only one processing gas supply system including the gas supply line144, the opening/closing valve148, the mass flow controller146and the processing gas source142is illustrated inFIG.1, the plasma processing apparatus100is actually equipped with a plurality of processing gas supply systems. For example, processing gases such as CF4, O2, N2and CHF3are supplied into the processing vessel102at independently controlled flow rates.

The electrode supporting body134is provided with, for example, a substantially cylindrical gas diffusion space135in which the processing gas introduced from the gas supply line144can be uniformly diffused. Further, a multiple number of gas discharge holes136is formed in a bottom portion of the electrode supporting body134and the electrode plate132to discharge the processing gas from the gas diffusion space135into the processing vessel102. The processing gas diffused in the gas diffusion space135can be uniformly discharged toward the plasma generation space from the gas discharge holes136. In this point of view, the upper electrode130serves as a shower head configured to supply the processing gas.

The upper electrode130is equipped with an electrode supporting body temperature controller137capable of controlling a temperature of the electrode supporting body134to a preset temperature. For example, the electrode supporting body temperature controller137is configured to circulate a temperature control medium into a temperature control medium path138provided within the electrode supporting body134.

A gas exhaust line104is connected to a bottom portion of the processing vessel102, and the gas exhaust line104is connected to a gas exhaust unit105. The gas exhaust unit105includes a vacuum pump such as a turbo molecular pump and is configured to adjust the inside of the processing vessel102into a preset decompressed atmosphere. The processing vessel102is evacuated as the gas exhaust unit105adjusts the inside of the processing vessel102into the preset decompressed atmosphere. Further, a carry-in/out opening106for the wafer W is provided at a sidewall of the processing vessel102, and a gate valve108is provided at the carry-in/out opening106. When a carry-in/out of the wafer W is performed, the gate valve108is opened. The wafer W is carried in or out through the carry-in/out opening106by a non-illustrated transfer arm or the like.

The upper electrode130is connected to a first high frequency power supply150, and a power feed line thereof is provided with a first matching device152inserted therein. The first high frequency power supply150is configured to output a high frequency power for plasma formation having a frequency ranging from 50 MHz to 150 MHz. By applying the power having such a high frequency to the upper electrode130, high-density plasma in a desirable dissociated state can be formed within the processing vessel102. Therefore, a plasma processing can be performed under a lower pressure condition. Desirably, a frequency of the output power of the high frequency power supply150may be in a range from 50 MHz to 80 MHz, and, typically, is adjusted to 60 MHz or thereabout.

The susceptor114configured as the lower electrode is connected to a second high frequency power supply160, and a power feed line thereof is provided with a second matching device162inserted therein. The second high frequency power supply160is configured to output a high frequency bias power having a frequency ranging from several hundreds of kHz to several tens of MHz. A frequency of the output power of the second high frequency power supply160is typically adjusted to, for example, 2 MHz, 13.56 MHz, or the like.

Further, the susceptor114is also connected with a high pass filter (HPF)164configured to filter a high frequency current flowing into the susceptor114from the first high frequency power supply150. The upper electrode130is connected to a low pass filter (LPF)154configured to filter a high frequency current flowing into the upper electrode130from the second high frequency power supply160.

An overall operation of the plasma processing apparatus100having the above-described configuration is controlled by a controller200. The controller200may be implemented by various kinds of integrated circuits or electronic circuits. By way of non-limiting example, ASIC (Application Specific Integrated Circuit), a CPU (Central Processing Unit), or the like may be used.

[Configurations of Placing Table, First Light Irradiation Unit, Second Light Irradiation Unit, First Adjusting Device and Second Adjusting Device]

Now, referring toFIG.2, configurations of major components of the placing table110, the first light irradiation unit172, the second light irradiation unit182, the first adjusting device174and the second adjusting device184will be explained.FIG.2is a schematic cross sectional view for describing the configurations of the major components of the placing table110, the first light irradiation unit172, the second light irradiation unit182, the first adjusting device174and the second adjusting device184shown inFIG.1.

The placing table110includes the substrate placing surface115afor placing the wafer W thereon, the focus ring placing surface116afor placing the focus ring FR thereon, and a rear surface119opposite to the substrate placing surface115aand the focus ring placing surface116a. The rear surface119faces the bottom102aof the processing vessel102with the space113therebetween. The substrate placing surface115ais an example of a first placing surface, and the focus ring placing surface116ais an example of a second placing surface.

The placing table110is provided with the first window124which allows the substrate placing surface115aand the rear surface119to communicate with each other and is capable of transmitting the light. The first window124is provided with a sealing member124amade of a material capable of transmitting the light. Further, the first light irradiation unit172configured to irradiate the light for the temperature measurement of the wafer W toward the first window124is provided at the bottom102aof the processing vessel102, corresponding to the position of the first window124. The first light irradiation unit172is held by the first adjusting device174and fixed by the first adjusting device174at the position of the through hole formed at the bottom102ato correspond to the position of the first window124.

The first adjusting device174is configured to hold the first light irradiation unit172and be capable of adjusting an irradiation position of the light reaching the rear surface119of the placing table110after being irradiated from the first light irradiation unit172.

A first reflection member192is disposed at the rear surface119of the placing table110to enclose the first window124. The first reflection member192has retroreflection property. The first reflection member192reflects a part of the light irradiated from the first light irradiation unit172and return the reflection light to the first light irradiation unit172. This reflection light indicates a deviation between the irradiation position of the corresponding light and the position of the first window124. That is, when maintenance of the placing table110is performed, for example, the first window124may be deviated from an initial position, and, as a result, the light irradiated toward the first window124from the first light irradiation unit172may be deviated to the vicinity of the first window124and irradiated to the rear surface119of the placing table110. In such a case, the first reflection member192returns the reflection light, which indicates the deviation between the irradiation position of the light at the rear surface119of the placing table110and the position of the first window124, to the first light irradiation unit172.

FIG.3is a plan view of the first reflection member192seen from the rear surface119side of the placing table110. As depicted inFIG.3, the first reflection member192has a cylindrical shape an edge of which lies on a concentric circle centered around the position of the first window124. A through hole through which the first window124is exposed is formed at a central portion of the first reflection member192. If the light irradiated from the first light irradiation unit172toward the first window124is deviated to the vicinity of the first window124and is thus irradiated to the rear surface119of the placing table110, there is generated a deviation between the irradiation position of the light at the rear surface119of the placing table110and the position of the first window124.FIG.3illustrates an irradiation position P of the light reaching the rear surface119of the placing table110after being irradiated from the first light irradiation unit172. The irradiation position P of the light is deviated from the position of the first window124. The first reflection member192reflects, at the irradiation position P, a part of the light irradiated from the first light irradiation unit172and returns the reflection light indicating the deviation between the irradiation position P and the position of the first window124to the first light irradiation unit172. The first adjusting device174adjusts the irradiation position P by moving the first light irradiation unit172along an x-axis and a y-axis which intersect with each other at the position of the first window124on the rear surface119of the placing table110as an origin [(x, y)=(0, 0)]. By way of example, the first adjusting device174adjusts the irradiation position P by moving the first light irradiation unit172along the x-axis and the y-axis in parallel with the rear surface119of the placing table110. Further, the first adjusting device174may be configured to adjust the irradiation position P by inclining the first light irradiation unit172along each of the x-axis and the y-axis.

Reference is made back toFIG.2. The first light irradiation unit172is connected to a first detector176by an optical fiber172a. The first detector176incorporates a light source and generates the light for the temperature measurement of the wafer W. The light generated by the first detector176is sent to the first light irradiation unit172via the optical fiber172aand irradiated toward the first window124from the first light irradiation unit172. If the light irradiated toward the first window124from the first light irradiation unit172is deviated to the vicinity of the first window124and irradiated to the rear surface119of the placing table110, the reflection light indicating the deviation between the irradiation position of the light and the position of the first window124is returned to the first light irradiation unit172from the first reflection member192. The reflection light returned to the first light irradiation unit172from the first reflection member192is guided to the first detector176via the optical fiber172a. The first detector176detects an intensity of the reflection light returned to the first light irradiation unit172from the first reflection member192, and outputs a detection result to the controller200. The controller200controls the first adjusting device174based on the detection result of the first detector176so that the irradiation position of the light at the rear surface119of the placing table110coincides with the position of the first window124.

Furthermore, the first light irradiation unit172is connected to a temperature measurer (not shown) by a spectrograph which is provided at a portion of the optical fiber172a. The temperature measurer irradiates the light for the temperature measurement of the wafer W toward the first window124from the first light irradiation unit172, and measures a temperature of the wafer W based on an interference state of the light reflected on the wafer W after being transmitted through the first window124. Since details of the method of measuring the temperature of the wafer W is described in, for example, Patent Document 1, explanation thereof will be omitted here.

Further, the placing table110is provided with the second window126which allows the focus ring placing surface116aand the rear surface119to communicate with each other and is capable of transmitting the light. The second window126is provided with a sealing member126amade of a material capable of transmitting the light. Further, the second light irradiation unit182configured to irradiate the light for the temperature measurement of the focus ring FR toward the second window126is provided at the bottom102aof the processing vessel102, corresponding to the position of the second window126. The second light irradiation unit182is held by the second adjusting device184and fixed by the second adjusting device184to the position of the through hole formed at the bottom102ato correspond to the position of the second window126.

The second adjusting device184is configured to hold the second light irradiation unit182and be capable of adjusting an irradiation position of the light reaching the rear surface119of the placing table110after being irradiated from the second light irradiation unit182.

A second reflection member194is disposed at the rear surface119of the placing table110to enclose the second window126. The second reflection member194has retroreflection property. The second reflection member194reflects a part of the light irradiated from the second light irradiation unit182and return the reflection light to the second light irradiation unit182. This reflection light indicates a deviation between an irradiation position of the corresponding light and the position of the second window126. That is, when maintenance of the placing table110is performed, for example, the second window126may be deviated from an initial position, and, as a result, the light irradiated toward the second window126from the second light irradiation unit182may be deviated to the vicinity of the second window126and irradiated to the rear surface119of the placing table110. In such a case, the second reflection member194returns the reflection light, which indicates the deviation between the irradiation position of the light at the rear surface119of the placing table110and the position of the second window126, to the second light irradiation unit182. The second reflection member194has a cylindrical shape an edge of which lies on a concentric circle centered around the position of the second window126. A through hole through which the second window126is exposed is formed at a central portion of the second reflection member194. The second adjusting device184adjusts the irradiation position of the light at the rear surface119of the placing table110by moving the second light irradiation unit182along an x-axis and a y-axis which intersect with each other at the position of the second window126on the rear surface119of the placing table110as an origin [(x, y)=(0, 0)].

The second light irradiation unit182is connected to a second detector186by an optical fiber182a. The second detector186incorporates a light source and generates the light for the temperature measurement of the focus ring FR. The light generated by the second detector186is sent to the second light irradiation unit182via the optical fiber182aand irradiated toward the second window126from the second light irradiation unit182. If the light irradiated toward the second window126from the second light irradiation unit182is deviated to the vicinity of the second window126and irradiated to the rear surface119of the placing table110, the reflection light indicating the deviation between the irradiation position of the light and the position of the second window126is returned to the second light irradiation unit182from the second reflection member194. The reflection light returned to the second light irradiation unit182from the second reflection member194is guided to the second detector186via the optical fiber182a. The second detector186detects an intensity of the reflection light returned to the second light irradiation unit182from the second reflection member194, and outputs a detection result to the controller200. The controller200controls the second adjusting device184based on the detection result of the second detector186so that the irradiation position of the light at the rear surface119of the placing table110coincides with the position of the second window126.

Furthermore, the second light irradiation unit182is connected to a temperature measurer (not shown) by a spectrograph which is provided at a portion of the optical fiber182a. The temperature measurer irradiates the light for the temperature measurement of the focus ring FR toward the second window126from the second light irradiation unit182, and measures a temperature of the focus ring FR based on an interference state of the light reflected on the focus ring FR after being transmitted through the second window126. Since details of the method of measuring the temperature of the focus ring FR is described in, for example, Patent Document 1, explanation thereof will be omitted here.

[Example of Adjusting Method by Controller]

FIG.4andFIG.5are diagrams for describing an example processing for adjusting the irradiation position of the light at the rear surface119of the placing table110toward the position of the first window124.FIG.4andFIG.5illustrate the first window124and the cylindrical first reflection member192which encloses the first window124. Further,FIG.4andFIG.5illustrate the x-axis and the y-axis intersecting with each other at the position of the first window124on the rear surface119of the placing table110as the origin. Furthermore,FIG.4andFIG.5also illustrate the irradiation position P of the light reaching the rear surface119of the placing table110after being irradiated from the first light irradiation unit172. The irradiation position P of the light is deviated from the position of the first window124.

By controlling the first adjusting device174, the controller200moves the first light irradiation unit172in a positive x-axis direction until the intensity of the reflection light detected by the first detector176becomes equal to or less than a threshold value ((1) ofFIG.4). Along with the movement of the first light irradiation unit172, the irradiation position P is moved in the positive x-axis direction. If the irradiation position P which is moved in the positive x-axis direction reaches the edge of the first reflection member192, the reflection light which is returned to the first light irradiation unit172from the first reflection member192disappears, so that the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value. The controller200stops the first adjusting device174at the moment when the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value, thus completing the movement of the first light irradiation unit172in the positive x-axis direction.

Thereafter, by controlling the first adjusting device174, the controller200moves the first light irradiation unit172in a negative x-axis direction until the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value ((2) ofFIG.4). Along with the movement of the first light irradiation unit172, the irradiation position P is moved in the negative x-axis direction. If the irradiation position P which is moved in the negative x-axis direction reaches the edge of the first reflection member192, the reflection light which is returned to the first light irradiation unit172from the first reflection member192disappears, so that the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value. The controller200stops the first adjusting device174at the moment when the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value, so that the movement of the first light irradiation unit172in the negative x-axis direction is completed. Then, the controller200measures a first maximum moving amount x1, which is a moving amount of the first light irradiation unit172until the movement in the negative x-axis direction is completed after the completion of the movement in the positive x-axis direction.

Subsequently, by controlling the first adjusting device174, the controller200moves the first light irradiation unit172by a half of the first maximum moving amount (x1/2) in the positive x-axis direction, thus allowing, with respect to the x-axis, an x-coordinate of the irradiation position P to coincide with an x-coordinate (x=0) of the position of the first window124((3) ofFIG.4).

Thereafter, by controlling the first adjusting device174, the controller200moves the first light irradiation unit172in a positive y-axis direction until the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value ((4) ofFIG.5). Along with the movement of the first light irradiation unit172, the irradiation position P is moved in the positive y-axis direction. If the irradiation position P which is moved in the positive y-axis direction reaches the edge of the first reflection member192, the reflection light which is returned to the first light irradiation unit172from the first reflection member192disappears, so that the intensity of the reflection light detected by the first detector176falls equal to or less than the threshold value. The controller200stops the first adjusting device174at the moment when the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value, thus completing the movement of the first light irradiation unit172in the positive y-axis direction.

Subsequently, by controlling the first adjusting device174, the controller200moves the first light irradiation unit172in a negative y-axis direction until the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value ((5) ofFIG.5). Along with the movement of the first light irradiation unit172, the irradiation position P is moved in the negative y-axis direction. If the irradiation position P which is moved in the negative y-axis direction reaches the edge of the first reflection member192, the reflection light which is returned to the first light irradiation unit172from the first reflection member192disappears, so that the intensity of the reflection light detected by the first detector176falls equal to or less than the threshold value. The controller200stops the first adjusting device174at the moment when the intensity of the reflection light detected by the first detector176becomes equal to or less than the threshold value, thus completing the movement of the first light irradiation unit172in the negative y-axis direction. Then, the controller200measures a second maximum moving amount y1, which is a moving amount of the first light irradiation unit172until the movement in the negative y-axis direction is completed after the completion of the movement in the positive y-axis direction.

Subsequently, by controlling the first adjusting device174, the controller200moves the first light irradiation unit172by a half of the second maximum moving amount (02) in the positive y-axis direction, thus allowing, with respect to the y-axis, a y-coordinate of the irradiation position P to coincide with a y-coordinate (y=0) of the position of the first window124((6) ofFIG.5).

Through the above-described operations, when the irradiation position of the light irradiated from the first light irradiation unit172is deviated from the position of the first window124, the plasma processing apparatus100is capable of moving the irradiation position to the position of the first window124by using the reflection light which is returned to the first light irradiation unit172from the first reflection member192. That is, the plasma processing apparatus100is capable of adjusting the irradiation position to the position of the first window124by scanning the irradiation position within a range of the first reflection member192, which is placed at the rear surface119of the placing table110facing the first light irradiation unit172, by using the reflection light from the first reflection member192. Therefore, in the plasma processing apparatus100, the range in which the irradiation position of the light is scanned can be narrowed, as compared to an adjusting method in which the irradiation position of the light is scanned at the entire rear surface119of the placing table110. As a result, a time required to adjust the irradiation position of the light can be shortened.

Besides, by repeating the adjustment with respect to the x-axis shown inFIG.4and the adjustment with respect to the y-axis shown inFIG.5multiple times, the irradiation position of the light can be made to be coincident with the position of the first window124with higher precision.

Further, assume a situation where the adjustment with respect to the x-axis shown inFIG.4is performed in a state that the y-coordinate of the irradiation position P is coincident with or close to the y-coordinate of the position of the first window124, or a situation where the adjustment with respect to the y-axis shown inFIG.5is performed in a state that the x-coordinate of the irradiation position P is coincident with or close to the x-coordinate of the position of the first window124. In these situations, if the irradiation position P is moved, the irradiation position P passes the first window124. At this time, there is no reflection light which is returned to the first light irradiation unit172from the first reflection member192, and the light reflected on the wafer W after being transmitted through the first window124is returned back to the first light irradiation unit172. Thus, the intensity of the reflection light detected by the first detector176may be varied. In this case, by comparing the intensity of the reflection light from the first reflection member192and the intensity of the reflection light from the wafer W, the plasma processing apparatus100is capable of making the irradiation position of the light coincident with the position of the first window124with higher precision.

Now, a flow of an irradiation position adjusting processing using the plasma processing apparatus100according to the exemplary embodiment will be described.FIG.6is a flowchart illustrating an example flow of the irradiation position adjusting processing according to the exemplary embodiment.

As depicted inFIG.6, the first detector176irradiates the light toward the first window124from the first light irradiation unit172and detects the intensity of the reflection light returned to the first light irradiation unit172from the first reflection member192(process S11). The first detector176outputs the detection result to the controller200.

Based on the detection result, the controller200controls the first adjusting device174so that the irradiation position of the light at the rear surface119of the placing table110coincides with the position of the first window124(process S12), and ends the irradiation position adjusting processing.

As stated above, a substrate processing apparatus according to the exemplary embodiment includes a placing table, a first adjusting device and a first reflection member. The placing table has a placing surface on which a substrate is placed and a rear surface opposite to the placing surface, and is provided with a first window which allows the placing surface and the rear surface to communicate with each other and is capable of transmitting light. A first adjusting device is configured to hold a first light irradiation unit which is configured to irradiate light for measurement of a state of the substrate toward the first window, and is capable of adjusting an irradiation position of the light reaching the rear surface of the placing table after being irradiated from the first light irradiation unit. The first reflection member has retroreflection property. The first reflection member is disposed at the rear surface of the placing table to enclose the first window, and reflects a part of the light irradiated from the first light irradiation unit and returns the reflection light indicating a deviation between the irradiation position of the light and a position of the first window to the first light irradiation unit. Accordingly, the substrate processing apparatus is capable of shortening a time required for the adjustment of the irradiation position of the light.

Further, the substrate processing apparatus according to the exemplary embodiment further includes a first detector and a controller. The first detector is configured to irradiate the light for the measurement of the state of the substrate toward the first window from the first light irradiation unit and detect an intensity of the reflection light returned to the first light irradiation unit from the first reflection member. Based on a detection result of the first detector, the controller controls the first adjusting device so that the irradiation position at the rear surface of the placing table coincides with the position of the first window. Accordingly, as compared to an adjusting method of scanning the irradiation position of the light at the entire rear surface of the placing table, the substrate processing apparatus is capable of narrowing a range in which the irradiation position of the light is scanned, and is thus capable of shortening the time required for the adjustment of the irradiation position of the light.

Furthermore, in the substrate processing apparatus, the first reflection member has a cylindrical shape an edge of which lies on a concentric circle centered around the position of the first window. The first adjusting device is configured to adjust the irradiation position by moving the first light irradiation unit along a first axis and a second axis which intersect with each other at the position of the first window as an origin at the rear surface of the placing table. Accordingly, the substrate processing apparatus is capable of narrowing the range in which the irradiation position of the light is scanned to a range defined along the two axes at the rear surface of the placing table. Therefore, the time required for the adjustment of the irradiation position of the light can be further shortened.

Moreover, in the substrate processing apparatus, the first reflection member has a cylindrical shape an edge of which lies on a concentric circle centered around the position of the first window. The first adjusting device is configured to adjust the irradiation position by inclining the first light irradiation unit along the first axis and the second axis which intersect with each other at the position of the first window as the origin at the rear surface of the placing table. Accordingly, the substrate processing apparatus is capable of narrowing the range in which the irradiation position of the light is scanned to the range defined along the two axes at the rear surface of the placing table. Therefore, the time required for the adjustment of the irradiation position of the light can be further shortened.

In addition, in the substrate processing apparatus according to the exemplary embodiment, the placing table has a second placing surface on which a ring member configured to surround the substrate is placed, and is provided with a second window which allows the second placing surface and the rear surface to communicate with each other and is capable of transmitting the light. Further, the substrate processing apparatus further includes a second adjusting device and a second reflection member. The second adjusting device is configured to hold a second light irradiation unit which is configured to irradiate light for measurement of a state of the ring member toward the second window, and is capable of adjusting an irradiation position of the light reaching the rear surface of the placing table after being irradiated from the second light irradiation unit. The second reflection member has retroreflection property. The second reflection member is disposed at the rear surface of the placing table to enclose the second window, and reflects a part of the light irradiated from the second light irradiation unit and returns the reflection light indicating a deviation between the irradiation position of the light and a position of the second window to the second light irradiation unit. Accordingly, the substrate processing apparatus is capable of shortening a time required for the adjustment of the irradiation position of the light for the measurement of the state of the substrate and the light for the measurement of the state of the ring member.

Moreover, the substrate processing apparatus according to the exemplary embodiment is further equipped with a second detector. The second detector is configured to irradiate the light for the measurement of the state of the ring member toward the second window from the second light irradiation unit and detect an intensity of the reflection light returned from the second reflection member to the second light irradiation unit. Based on a detection result of the second detector, the controller controls the second adjusting device so that the irradiation position at the rear surface of the placing table coincides with the position of the second window. Accordingly, as compared to the adjusting method of scanning the irradiation position of the light at the entire rear surface of the placing table, the substrate processing apparatus is capable of narrowing the range in which the irradiation position of the light is scanned, and is thus capable of shortening the time required for the adjustment of the irradiation position of the light.

Furthermore, it should be noted that the above-described exemplary embodiments are illustrative in all aspects and are not anyway limiting. The above-described exemplary embodiments may be omitted, replaced and modified in various ways without departing from the scope and the spirit of claims.

In the above-described exemplary embodiment, the first reflection member192and the second reflection member194have the cylindrical shape. However, the shape of each reflection member is not limited thereto. By way of example, the reflection member may have a rectangular barrel shape having a regular distance from each side thereof to the position of the window.

Further, an optical path adjuster may be provided between the first light irradiation unit172and the rear surface119of the placing table110, and between the second light irradiation unit182and the rear surface119of the placing table110.

In addition, the above exemplary embodiment has been described for the example case where the irradiation position is adjusted by moving the first light irradiation unit172along the x-axis and the y-axis based on the intensity of the reflection light detected by the first detector176. However, the present disclosure is not limited thereto. By way of example, after moving the first light irradiation unit172along the x-axis and the y-axis, the plasma processing apparatus100may search for a position where the intensity of the reflection light detected by the first detector176is maximized and then finely adjust the irradiation position toward the found position.

According to the exemplary embodiment, it is possible to shorten the time required to adjust the irradiation position of the light.