Patent Publication Number: US-10770273-B2

Title: OES device, plasma processing apparatus including the same and method of fabricating semiconductor device

Description:
This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2018-0016378 filed on Feb. 9, 2018 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an OES (Optical Emission Spectroscopy) device, a plasma processing apparatus including the same, and a method of fabricating a semiconductor device. 
     2. Description of the Related Art 
     Recently, a system which accelerates desired chemical reaction (film formation, etching, etc.) using plasma has been widely used in the semiconductor device fabricating industry. 
     An OES (Optical Emission Spectroscopy) device is used for optically diagnosing the presence or absence of abnormalities in the plasma process. The OES device has an advantage that the uniformity of the plasma in the chamber can be determined from the outside of the chamber, without requiring insertion of a probe into the chamber. 
     SUMMARY 
     Exemplary embodiments of the present disclosure provide an OES device with improved detection performance of abnormality occurrence of a plasma process. 
     Exemplary embodiments of the present disclosure provide a plasma processing apparatus including an OES device with improved detection performance of abnormality (or out of specification) occurrence of the plasma process. 
     Exemplary embodiments of the present disclosure provide a method of fabricating a semiconductor device using improved OES analysis. 
     According to an exemplary embodiment of the present disclosure, there is provided a plasma processing apparatus, comprising a chamber configured to perform a plasma process on a wafer, a viewport configured to transmit plasma light generated in the chamber, a rotation module coupled to the viewport to be rotatable around a rotation axis, and an OES (Optical Emission Spectroscopy) device which is coupled to the rotation module and configured to receive the plasma light, wherein the rotation module includes a first surface facing the viewport and a second surface facing the OES device, wherein the first surface is configured to block a part of the plasma light, and includes a first opening through which an inside of the rotation module is configured to be exposed to a part of the plasma light, and wherein the second surface includes a second opening configured to be in light communication with the first opening. 
     According to an exemplary embodiment of the present disclosure, there is provided an OES (Optical Emission Spectroscopy) device, comprising a rotation module coupled to a viewport of a chamber, the rotation module configured to transmit plasma light generated in the chamber, the rotation module configured to be rotatable around a rotation axis, a light-receiving part coupled to the rotation module and configured to receive the plasma light, a spectroscope configured to separate the plasma light and analyzes intensities of corresponding wavelengths and an optical cable which connects the light-receiving part and the spectroscope, wherein the rotation module includes a first surface coupled to the viewport and a second surface coupled to the light-receiving part, wherein the first surface is configured to block a part of the plasma light, and includes a first opening through which an inside of the rotation module is configured to be exposed by the first blocking film, and wherein the second surface includes a second opening configured to be in light communication with the first opening. 
     According to an exemplary embodiment of the present disclosure, there is provided a method of fabricating a semiconductor device, comprising inputting a wafer into a chamber in which an OES (Optical Emission Spectroscopy) device is connected to a viewport through a rotation module, injecting a process gas into the chamber and applying RF power to generate a plasma, positioning the rotation module at a first angle to monitor the plasma in the chamber by using plasma light transmitted through the viewport, rotating the rotation module by a second angle to monitor the plasma in the chamber by using plasma light transmitted through the viewport, comparing monitoring result of the plasma at the first angle and the second angle to determine a plasma uniformity in the chamber, and adjusting process variables of the chamber, wherein the OES device includes the rotation module coupled to the viewport so as to be rotatable around a rotation axis, the rotation module including a first surface coupled to the viewport and a second surface coupled to a light-receiving part, the first surface including a first blocker which blocks a part of a plasma light, and a first opening through which an inside of the rotation module is exposed to a part of the plasma light, and the second surface including a second opening in light communication with the first opening. 
     Exemplary embodiments of the present disclosure are not limited to those mentioned above and another aspect which has not been mentioned can be clearly understood by those skilled in the art from the description below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other exemplary embodiments and features of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
         FIG. 1  is a diagram illustrating a plasma processing apparatus according to some embodiments of the present disclosure; 
         FIG. 2  is a plan view of a plasma processing apparatus having an OES device showing an operation of the OES device; 
         FIG. 3 a    is a perspective view of a rotation module included in an OES device according to some embodiments of the present disclosure; 
         FIG. 3 b    is a top view illustrating the rotation module of  FIG. 3 a    from a B direction shown in  FIG. 3   a;    
         FIG. 4 a    is a cross-sectional view taken along line A-A′ of the rotation module of  FIG. 3   a;    
         FIG. 4 b    is a plan view a plasma processing apparatus including an OES device according to some embodiments of the present disclosure; 
         FIGS. 5 a  to 5 d    are diagrams of a rotation module included in an OES device according to some embodiments of the present disclosure; 
         FIG. 6  is a graph of light intensity spectroscopic analysis obtained by operation of an OES device according to some embodiments of the present disclosure; 
         FIG. 7  is a perspective view of a rotation module included in an OES device according to some embodiments of the present disclosure; 
         FIGS. 8 a  to 8 d    are diagrams of a rotation module included in an OES device and illustrate an operation of the rotation module according to some embodiments of the present disclosure; and 
         FIG. 9  is a flowchart illustrating a method of fabricating a semiconductor device performed by a plasma processing apparatus according to some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a view for explaining a plasma processing apparatus according to some embodiments of the present disclosure. 
     Referring to  FIG. 1 , a plasma processing apparatus according to some embodiments of the present disclosure may include an electrostatic chuck  10 , a shower head  20 , a gas supply port  30 , an RF power supply  40 , a chamber  50 , a gas discharge port  60 , a viewport  80 , a rotation module  100 , a light-receiving part  200 , and the like. 
     The electrostatic chuck  10  may support a wafer W which is introduced into the chamber  50 . The electrostatic chuck  10  may have, but is not limited to, a circular planar shape to support a circular wafer W. The electrostatic chuck  10  may fix the wafer W to an upper surface thereof by electrostatic force. In a plasma processing step using the plasma processing apparatus according to an embodiment of the present disclosure, the electrostatic chuck  10  may function as a lower electrode. 
     A shower head  20  may be placed over the electrostatic chuck  10  inside the chamber  50 . The shower head  20  may supply a process gas, which is supplied through the gas supply port  30  in the plasma processing step, into the chamber  50 . The shower head  20  may function as an upper electrode to which the RF power supply  40  is applied in the plasma processing step. Although it is not specifically illustrated, a plurality of openings may be formed on a first surface of the shower head  20  and the first surface may face the electrostatic chuck  10 . 
     The chamber  50  may receive the process gas supplied from the gas supply port  30 . In some embodiments of the present disclosure, the process gas may be a mixture of two or more gases. 
     Inside the chamber  50 , a plasma P may be formed from the supplied process gas. The chamber  50  may include a space in which the plasma processing step of the wafer W is performed, using the formed plasma P. In some embodiments of the present disclosure, a deposition process, an etching process, and the like of the wafer W may be performed in the chamber  50 , but the present disclosure is not limited thereto. The chamber  50  may discharge the process gas via the gas discharge port  60  after the execution of the plasma process is completed. The gas discharge port  60  may adjust the pressure in the chamber  50 . For example, by controlling amount and/or speed of the discharge of the process gas through the gas discharge port  60 , the pressure in the chamber  50  may be adjusted. 
     As illustrated in  FIG. 1 , the chamber  50  may operate in a CCP (Capacitively Coupled Plasma) manner, but it is not limited thereto. The chamber  50  may also operate in an (ICP Inductively Coupled Plasma) manner. For example, the plasma P in the chamber  50  may be generated and/or controlled with a CCP method or with an ICP method. 
     The RF power supply  40  supplies power for forming the plasma P in the chamber  50 . For example, the RF power supply  40  may apply the RF power to the shower head  20 . The RF power supply  40  may supply, for example, power in the form of a pulse modulated square wave to the shower head  20 . 
     The RF power supply  40  may include an impedance matching circuit for minimizing the reflected power of an electric circuit formed between the shower head  20  and the electrostatic chuck  10 . 
     The viewport  80  may be installed so that the inside of the chamber  50  can be monitored through the viewport  80 . The viewport  80  may be connected to a rotation module  100  coupled to the light-receiving part  200  and may function as a passage for providing the state of plasma light in the chamber  50  to the light-receiving part  200 . 
     The viewport  80  may include, for example, a transparent material such as glass or quartz, but is not limited thereto, and may include materials such as polycarbonate and acryl. 
     The rotation module  100  may be coupled to the viewport  80  and the light-receiving part  200 . The rotation module  100  may provide a part of the plasma light from the chamber  50  provided through the viewport  80  to the light-receiving part  200 , while revolving around a rotation axis. The operation of the rotation module  100  will be explained in more detail later. 
     The light-receiving part  200  may receive plasma light generated in the chamber  50 . The plasma light provided to the light-receiving part  200  may be light which is left after being partially blocked by the rotation module  100 , among the light transmitted to the viewport  80 . Likewise, this will be explained below in more detail. 
     The optical cable  210  is connected to the light-receiving part  200 , and may transfer the plasma light coming from the chamber  50  transmitted through the viewport  80  to a spectroscope  220 . In some embodiments, the optical cable  210  may include a bundle of multiple optical fibers wrapped in fabric. 
     The rotation module  100 , the light-receiving part  200  and the optical cable  210  connected to the viewport  80  may constitute an OES (Optical Emission Spectroscopy) device. 
     The spectroscope  220  may receive plasma light coming from the chamber  50  through the optical cable  210 . The spectroscope  220  may analyze the light provided via the optical cable  210  and analyze the state of the plasma P in the chamber  50 . For example, the spectroscope  220  may analyze the light coming from the plasma P and evaluate the state of the plasma P with the result of the analysis of the light. The spectroscope  220  may spectrally separate the plasma light coming from the chamber  50 , for example, provided through the optical cable  210  in accordance with the wavelength, and may measure the intensity of light depending on the wavelength (e.g., intensities of corresponding wavelengths). For example, the spectroscope  220  may measure intensities of respective electromagnetic waves and/or wave bands in a predetermined wavelength range. For example, the predetermined wavelength range may include a portion of or all visible light range. 
     The spectroscopic result measured by the spectroscope  220  may be provided to the controller  230 . The controller  230  may control the plasma process executed in the chamber  50 , using the measured spectroscopic result. 
     In some embodiments, the controller  230  may control the process variables of the plasma process performed in the chamber  50  when it determines that an abnormality (e.g., a condition out of specification) has occurred in the plasma process by the measurement result. The process variables controlled by the controller  230  may include, for example, but are not limited to, an impedance of a connected impedance matching circuit included in the RF power supply  40 , a gas pressure of a chamber  50  controlled by a gas discharged to the discharge port  60 , an amount of process gas provided to the gas supply port  30 , a temperature in the chamber  50 , and the like. For example, the gas pressure of the chamber  50  may be controlled by the amount of gas in the chamber  50  which may be controlled by supply and/or discharge of the gas through the gas supply port  30  and/or the discharge port  60 . 
       FIG. 2  is a plan view of a general plasma processing apparatus including an OES device. 
     Referring to  FIG. 2 , the OES device receives the plasma light generated from the chamber  50  through the viewport  80 . The light-receiving part  200  is directly connected to the viewport  80 , and the plasma light measured by the light-receiving part  200  is provided to the spectroscope  220  via the optical cable  210 . For example, the plasma light may be electromagnetic waves generated from the plasma within the chamber  50 . For example, the electromagnetic waves generated from the plasma may include visible light and/or electromagnetic waves outside visible light. For example, the electromagnetic waves generated from the plasma may be generated by electron transitions from higher energy levels to lower energy levels. 
     A range A of the incident angle of the plasma light that can be accommodated by the viewport  80  and the light-receiving part  200  is limited to about 30 to 40°. As illustrated in  FIG. 2 , the upper surface of the wafer W which can be covered by the range A of the incident angle of the plasma light occupies only a part of the area of the wafer W. Therefore, the range A of the incident angle of the plasma light may be somewhat insufficient for determining the presence or absence of abnormality (or out of specification) of the plasma light in the chamber  50  through measurement of the uniformity of the plasma light in the chamber  50 . For example, when the viewport  80  and the light-receiving part  200  are fixed with respect to the chamber  50 , the range A from which the light-receiving part  200  receives light generated from the plasma in the chamber  50  overlaps limited portion of the wafer W, e.g., 50% or less of the whole area of the wafer W in a plan view. 
     The OES device according to some embodiments of the present disclosure may expand the range of the incident angle of the plasma light which can be accommodated by the viewport  80  and the light-receiving part, by utilizing the rotation module ( 100  of  FIG. 1 ). A detailed description thereof will be provided later. 
       FIG. 3 a    is a perspective view of a rotation module according to some embodiments of the present disclosure, and  FIG. 3 b    is a top view illustrating the rotation module of  FIG. 3 a    seen from the B direction indicated in  FIG. 3   a.    
     Referring to  FIGS. 3 a  and 3 b   , the rotation module  100  may include a first surface  130 , a first opening  110  formed on the first surface  130 , a second surface  140 , and a second opening  120  formed on the second surface  140 . 
     The rotation module  100  may have a cylindrical shape. For example, the rotation module  100  may have a first surface  130  which is a circular upper surface, and a second surface  140  which is a circular lower surface. 
     The first surface  130  of the rotation module  100  is a surface facing the viewport  80 , and the second surface  140  of the rotation module  100  is a surface facing the light-receiving part  200 . 
     For example, the first surface  130  may be brought into contact with the viewport  80  when the rotation module  100  and the viewport  80  are coupled, and the second surface  140  may be brought into contact with the light-receiving part  200  when the rotation module  100  and the light-receiving part  200  are coupled. However, the present disclosure is not limited thereto, and when the rotation module  100  and the viewport  80  are coupled through another coupling module, the first surface  130  and the viewport  80  may not be brought into contact with each other. Likewise, when the rotation module  100  and the light-receiving part  200  are coupled through another coupling module, the second surface  140  and the light-receiving part  200  may not be brought into contact with each other. 
     The rotation module  100  may be coupled to the viewport  80  so as to be rotatable about the rotation axis  150 . The rotation axis  150  may pass through a center (e.g., the center of gravity or a geometric center) of the rotation module  100  in the B direction. 
     In  FIGS. 3 a  and 3 b   , the first opening  110  may be formed on the first surface  130  to have a semicircular shape. For example, the first opening  110  may be a remaining part of the first surface  130  except the portion blocked by a first blocking film  115  having another semicircular shape on the first surface  130  having a circular shape. However, the shape of the first opening  110  is not limited to a semicircle, and the shape of the first opening  110  may vary depending on a portion on the first surface  130  blocked by the first blocking film  115 . The first opening  110  may expose the inside of the rotation module  100  by the first blocking film  115 . Though a blocking film is described, other types of blockers may be used so that the first opening  110  is configured to block part of the light from the chamber  50 . For example, the blockers may block a part of plasma light coming from the chamber  50 . 
     The second opening  120  may be formed on the second surface  140  to have a semicircular shape. For example, the second opening  120  may be a remaining portion of the second surface  140  except the portion blocked by the second blocking film  125  having another semicircular shape in the second surface  140  having a circular shape. The second opening  120  may be connected to the first opening  110 , e.g., in light communication with the first opening  110 , through an inner portion of the cylindrical shape of the rotation module  100 . The second opening  120  may be formed in the same shape as the first opening  110 . Therefore, when the first opening  110  is a semicircle, the second opening  120  may also be formed in a semicircular shape. For example, the first opening  110  and the second opening  120  may be similar and may have similarities, e.g., in a plan view. For example, a plan view shape of the second opening  120  may be obtained from a plan view shape of the first opening  110  by uniformly scaling (enlarging or reducing) the first opening  110 . 
     A first radius r 1  of the first opening  110  and a second radius r 2  of the second opening  120  may be different from each other. For example, the first radius r 1  of the first opening  110  may be larger than the second radius r 2  of the second opening  120 . The first radius r 1  of the first opening  110  may correspond to the size of a window formed in the viewport  80 , and the second radius r 2  of the second opening  120  may correspond to the size of the opposing surface of the light-receiving part  200 . 
       FIG. 4 a    is a cross-sectional view taken along line A-A′ of the rotation module of  FIG. 3   a.    
     Referring to  FIG. 4 a   , a state in which the plasma light generated inside the chamber  50  and passing through the viewport ( 80  of  FIG. 1 ) is incident on the rotation module  100  is illustrated. 
     As described above, the first blocking film  115  may be formed on the first surface  130  of the rotation module  100 , thereby blocking a part of the plasma light L 1  incident on the first surface  130 . A part L 2  of the plasma light having passed through the first opening  110  passes through the rotation module  100  and exits from the second opening  120 . The plasma light L 2  exiting from the second opening  120  is provided to the light-receiving part  200 . 
     Referring to  FIG. 4 b   , a first area A 1  blocked by the blocking film  115  in the chamber  50  and a second area A 2  in which plasma light can be detected by the OES device are dividedly indicated. For example, plasma light coming from the first area A 1  may be blocked by the blocking film  115  of  FIG. 4 a   , and plasma light coming from the second area A 2  may be incident through the rotation module  100  of  FIG. 4 a   . Here, in  FIG. 4 b   , a left area of the chamber is defined as the first area A 1 , and a right area of the chamber  50  is defined as the second area A 2 . 
     For example, even though the range of the incident angle of the plasma light that can be accommodated by the viewport  80  and the light-receiving part  200  may be still limited to 30 to 40°, the plasma light coming from area A 2  may be detected while the plasma light coming from area A 1  in the chamber  50  is blocked by the blocking film  115 . While the structures and functions of the rotation module  110  are described above, the invention is not limited to the above described structures and/or the functions. For example, the rotation module  110  may be other types of rotation module capable of detecting plasma light coming from different areas of the chamber  50 . In certain embodiments, the plasma processing apparatus may include a module other than the rotation module  110 , e.g., a sweeping module or a scanning module which are capable of detecting different portions/areas of the chamber  50 . 
     The determination of the uniformity of the plasma P in the chamber  50  may include detection of the plasma light coming from the first area A 1  and the second area A 2 , and comparison of uniformity (or states/characteristics) of the plasma P between both areas. Hereinafter, determination of the uniformity of the plasma P in the chamber  50  will be described. 
       FIGS. 5 a  to 5 d    are plan views of the rotation module  100  and illustrate an operation of the rotation module according to some embodiments of the present disclosure. 
     First, referring to  FIG. 5 a   , the plasma light coming from the chamber  50  is monitored when the rotation module  100  is positioned at 0°, e.g., a datum point as illustrated in  FIG. 5 a   . As described with respect to  FIGS. 4 a  and 4 b   , when the rotation module  100  is positioned at 0°, plasma light coming from the first area A 1  is blocked by the blocking film  115 , and plasma light coming from the second area A 2  may be transferred through the first opening  110  to the light-receiving part  200  and may be detected and/or monitored by the light-receiving part  200 . 
     Referring to  FIG. 5 b   , the plasma light coming from the chamber  50  is monitored when the rotation module  100  rotated by 90° (or positioned at 90°) with respect to the datum point. When the rotation module  100  rotates by 90° (or positions at 90°) with respect to the datum point as shown in  FIG. 5 b   , the plasma light coming from the upper end portion of the chamber  50  is blocked by the blocking film  115 , and monitoring of plasma light coming from the lower end portion of the chamber  50  may be performed with the plasma light coming through the first opening  110 . For example, a part of the first area A 1  and a part of the second area A 2  of the chamber  50  may be simultaneously monitored with the plasma light coming through the first opening  110 . 
     Next, referring to  FIG. 5 c   , the plasma light coming from the chamber  50  may be transferred through the rotation module  100  rotated by 180° (or positioned at 180°) with respect to the datum point and may be detected and/or monitored by the light-receiving part  200 . When the rotation module  100  rotates by 180° (or positions at 180°) with respect to the datum point as shown in  FIG. 5 c   , plasma light coming from the second area A 2  is blocked by the blocking film  115  and the first area A 1  may be monitored with plasma light coming through the first opening  110 . 
     Subsequently, referring to  FIG. 5 d   , the plasma light coming from the chamber  50  may be transferred through the rotation module  100  rotated by 270° (or positioned at 270°) with respect to the datum point and may be detected and/or monitored by the light-receiving part  200 . When the rotation module  100  rotates by 270° (or positions at 270°) with respect to the datum point as shown in  FIG. 5 d   , the plasma light coming from the lower end portion of the chamber  50  is blocked by the blocking film  115 , and monitoring of the plasma light coming from the upper end portion of the chamber  50  may be performed with plasma light coming through the first opening  110 . For example, a part of the first area A 1  and a part of the second area A 2  of the chamber  50  may be simultaneously monitored with plasma light coming through the first opening  110 . 
     In order to determine the uniformity of the plasma P in the first area A 1  and the second area A 2  in the chamber  50 , the plasm light coming through the first opening  110  when the rotation module  100  rotates by a first angle from the datum point may be compared with the plasma light coming through the first opening  110  when the rotation module  100  rotates by a second angle from the datum point. In some embodiments of the disclosure, the first angle may be 0° and the second angle may be 180°. For example, the plasma light coming through the first opening  110  when the rotation module  100  is positioned at the first angle from the datum point may come from different part of the plasma than the part of the plasma from which the plasma light coming through the first opening  110  when the rotation module  100  is positioned at the second angle from the datum point. 
     When the monitoring results of the plasma light with the rotation module  100  positions at the first angle and the second angle are different from each other, it may be determined that an abnormality (or a condition out of specification) has occurred in the plasma uniformity in the chamber  50 . The determination of the uniformity of the plasma in the chamber  50  may be performed in real time, without interrupting the plasma process in the chamber  50 . 
       FIG. 6  is a graph of light intensity spectroscopic analysis obtained by operation of the rotation module and the OES device according to some embodiments of the present disclosure. 
     Referring to  FIG. 6 , the graph shows normalized intensities of the plasma light transferred through the first opening  110  while the rotation module  100  rotates. The intensity of the plasma light at the time t 1  is a case monitored when the rotation module  100  rotates by the first angle from the datum point, and the intensity of the plasma light at the time t 2  is a case monitored when the rotation module  100  rotates by the second angle from the datum point. 
     As illustrated in  FIG. 6 , when the intensities of the plasma light at the time t 1  and t 2  appear different (e.g., by a certain value or percentage of intensity) from each other, it may be determined that abnormality (or a condition out of specification) has occurred in the plasma uniformity in the chamber  50 . 
     If it is determined that abnormality (or a condition out of specification) has occurred in the uniformity of the chamber  50 , the plasma process in the chamber  50  may be interrupted, and process variables of the plasma process may be adjusted. For example, after the impedance of a connected impedance matching circuit included in the RF power supply  40 , the gas pressure of the chamber  50  controlled by the gas discharged through the discharge port  60 , the amount of process gas provided to the gas supply port  30 , the temperature in the chamber  50  and the like are adjusted, the plasma process performed in the chamber  50  may be resumed with the adjusted process variables. 
       FIG. 7  is a perspective view of a rotation module according to some embodiments of the present disclosure. 
     Referring to  FIG. 7 , the rotation module  300  may include a first surface  330 , a first opening  310  formed in the first surface  330 , a second surface  340 , and a second opening  320  formed on the second surface  340 . 
     The rotation module  300  illustrated in  FIG. 7  differs from the rotation module  100  illustrated in  FIG. 3 a    in that the shapes of the first opening  310  and the second opening  320  formed in the rotation module  300  are different from those of the first opening  110  and the second opening  120  illustrated in  FIG. 3   a.    
     The shapes of the first opening  310  and the second opening  320  may have a quadrant shape. For example, the blocking film  315  disposed on the first surface  330  may block ¾ of the first surface  330  and may open the rest as the first opening  310 . For example, the blocking film  315  may cover about ¾ of the rotation module  300  in a plan view. For example, the blocking film  315  may have an open area of one quadrant of the first surface  330  in a plan view. Similarly, the blocking film of the second surface  340  may also block ¾ of the second surface  340  and may open the rest as the second opening  320 . For example, the blocking film disposed on the second surface  340  may have an open area of one quadrant of the second surface  340  in a plan view. 
       FIGS. 8 a  to 8 d    are plan views of the rotation module  300  of  FIG. 7  and illustrate an operation of the rotation module  300  according to some embodiments of the present disclosure. 
     Referring to  FIG. 8 a   , the plasma light coming from the chamber  50  is monitored when the rotation module  300  is positioned at 0°, e.g., a datum point. When the rotation module  300  is positioned at 0°, the plasma light coming from a part of the second area A 2  and the whole first area A 1  may be blocked by the blocking film  315 , and the plasma light coming from another part of the second area A 2  may be transferred through the first opening  310  and may be detected/monitored by the light-receiving part  200 . Here, the latter part of the second area A 2  may correspond to the upper part of the second area A 2 . 
     Next, referring to  FIG. 8 b   , the plasma light coming from the chamber  50  is monitored when the rotation module  300  rotated by (or positioned at) 90° from the datum point. When the rotation module  300  rotates by (or positons at) 90° from the datum point, plasma light coming from a part of the second area A 2  and the first area A 1  are blocked by the blocking film  315 , and plasma light coming from another part of the second area A 2  may be transferred through the first opening  310  and may be detected/monitored by the light-receiving part  200 . Here, the latter part of the second area A 2  may correspond to the lower part of the second area A 2 . 
     Next, referring to  FIG. 8 c   , the plasma light coming from the chamber  50  is monitored when the rotation module  300  rotated by (or positioned at) 180° from the datum point. When the rotation module  300  rotates by (or positions at) 180° from the datum point, plasma light coming from a part of the first area A 1  and the whole second area A 2  may be blocked by the blocking film  315 , and plasma light coming from another part of the first area A 1  may be transferred through the first opening  310  and may be detected/monitored by the light-receiving part  200 . Here, the latter part of the first area A 1  may correspond to the lower part of the first area A 1 . 
     Subsequently, referring to  FIG. 8 d   , the plasma light coming from the chamber  50  is monitored when the rotation module  300  rotated by (or positioned at) 270° from the datum point. When the rotation module  300  rotates by (or positions at) 270° from the datum point, plasma light coming from a part of the first area A 1  and the whole second area A 2  may be blocked by the blocking film  315 , and plasma light coming from another part of the first area A 1  may be transferred through the first opening  310  and may be detected/monitored by the light-receiving part  200 . Here, the latter part of the first area A 1  may correspond to the upper part of the first area A 1 . For example, the former part of the first area A 1  and the upper part of the first area A 1  may compose the whole first area A. For example, the first area A 1  may be a half of the whole area for which the OES device monitors plasma P in the chamber  20 . For example, the second area A 2  may be the other half of the whole area for which the OES device monitors plasma P in the chamber  20 . 
     In order to determine the uniformity of the plasma P in the first area A 1  and the second area A 2  inside the chamber  50 , the plasma light monitored by the OES device when the rotation module  300  rotates by a first angle may be compared with the plasma light monitored by the OES device when the rotation module  300  rotates by a second angle. In some embodiments of the present disclosure, the first angle may be 0° and the second angle may be 270°. 
     At this time, when comparing the plasma light transferred through the first opening  310  when the rotation module  300  rotates by 0° and 270° with respect to a datum point, plasma states of the upper part of the first area A 1  and the upper part of the second area A 2  may be monitored. 
     In certain embodiments, the plasma light transferred through the first opening  310  when the rotation module  300  rotates by a third angle may be compared with the plasma light transferred through the first opening  310  when the rotation module  300  rotates by a fourth angle. In some embodiments of the present disclosure, the third angle may be 90° and the fourth angle may be 180° from the datum point. 
     When comparing the plasma lights coming through the first opening  310  when the rotation module  300  rotates by 90° and 180° respectively with respect to the datum point, the plasma states of the lower part of the first area A 1  and the lower part of the second area A 2  may be monitored. 
     For example, in the case of the OES device described through this embodiment, the uniformity of the plasma in the chamber  50  may be monitored by dividing the chamber  50  into the upper part and the lower part of the chamber  50 . While a plasma process is performed in the chamber  50 , the upper part of the chamber  50  close to the shower head  20  functioning as an upper electrode, and the lower part of the chamber  50  close to the electrostatic chuck  10  functioning as a lower electrode may have plasma states different from each other. Therefore, in order to determine the uniformity and/or states of the plasma, the monitoring of the plasma may be performed by dividing the upper part and the lower part of the chamber  50 , the uniformity and/or states of the plasma in the monitored chamber  50  may be determined accordingly. 
       FIG. 9  is a flowchart illustrating a method of fabricating a semiconductor device performed by the plasma processing apparatus according to some embodiments of the present disclosure. 
     Referring to  FIG. 9 , the method of fabricating the semiconductor device performed by the plasma processing apparatus according to some embodiments of the present disclosure may include a step of inputting the wafer W into the chamber  50  in which the OES device is connected to the viewport  80  via the rotation module  100  (S 110 ); a step of injecting a process gas into the chamber  50  and applying RF power to generate a plasma P (S 120 ); a step of detecting plasma light through the EOS device in a state in which the rotation module  100  rotates by a first angle (S 130 ); a step of detecting the plasma light through the EOS device in a state in which the rotation module rotates by the second angle (S 140 ); a step of comparing the detection results of the plasma light at the first angle and the second angle (S 150 ); a step of determining whether abnormality (or a condition out of specification) occurs in the plasma light (S 160 ); and a step of adjusting process variables of the plasma process when there is abnormality (or a condition out of specification) (S 170 ). 
     After uniformity of the plasma light is inspected via the OES device, uniformity inspection of the plasma light may be performed again through the OES device, while continuously performing the plasma process on different wafers W. 
     The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will appreciate that many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the present disclosure. Therefore, the disclosed preferred embodiments of the disclosure are used in a generic and descriptive sense only and not for purposes of limitation.