Patent Publication Number: US-2022230839-A1

Title: Faraday shield and apparatus for treating substrate

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     A claim for priority under 35 U.S.C. § 119 is made to Korean Patent Application No. 10-2021-0007682 filed on Jan. 19, 2021, in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     Embodiments of the inventive concept described herein relate to a Faraday shield and a substrate processing apparatus. 
     Examples of a substrate processing apparatus using plasma may include a substrate processing apparatus using inductively coupled plasma (ICP) and a substrate processing apparatus using capacitively coupled plasma (CCP). 
     In the case of the substrate processing apparatus using the inductively coupled plasma, not only inductive coupling but also capacitive coupling occurs between an RF coil and plasma, and an electric field like a capacitor is formed in a vertical direction in a process chamber. The capacitance of the virtual capacitor formed in the vertical direction applies, inside the process chamber, the electric field between the plasma and a wall and between the plasma and a substrate and causes charged particles constituting the plasma to be accelerated by the electric field. When the accelerated plasma particles collide with the wall or the substrate, the temperature in the process chamber and the temperature of the substrate are raised, and a surface of the substrate is damaged. 
     To remove the electric field in the vertical direction, a Faraday shield is provided between the process chamber and the RF coil. 
     An existing Faraday shield lets a magnetic field pass and blocks an electric field, thereby preventing damage to a dielectric that is generated by a potential difference between plasma and an antenna. However, as a substrate becomes larger, a plasma source also becomes larger, and a Faraday shield also becomes larger and has a sensitive influence on equipment in response to a temperature change. 
     Because a large-sized Faraday shield has a high thermal expansion rate and the length by which the large-sized Faraday shield is actually expanded is very great, a phenomenon such as thermal expansion or distortion occurs, and delamination (shown by a dotted line in  FIG. 1 ), which is physical damage, occurs at a plasma source to which the Faraday shield is assembled (refer to  FIG. 1 ). 
     As in  FIGS. 2A and 2B , the length and diameter of a Faraday shield may be greatly changed depending on a temperature deviation. The temperature of semiconductor process equipment is actually elevated to several hundred degrees Celsius. In the case of a dielectric (Quartz, a thermal expansion rate of 0.0005 mm/° C.) that is closely attached to the Faraday shield (Al, a thermal expansion rate of 0.024 mm/° C.), the thermal expansion rate is about 1/50 of that of Al. As temperature rises and the size of the Faraday shield is increased, the dielectric is very vulnerable to damage by thermal expansion, and for the purpose of an optimized semiconductor process, a process temperature cannot be lowered. Therefore, there is difficulty in management of damage, maintenance, and manufacturing yield of a plasma source. 
     To solve these problems, other researchers have considered various dielectric materials and Faraday shields formed of various materials. However, a material (Cu) that is avoided in a semiconductor process or a material (Mo) that has a low thermal expansion rate, but is problematic in terms of rolling and cost generates particles at high temperature despite a low thermal expansion rate and relatively low cost. Therefore, it is difficult to change the material of a Faraday shield. Furthermore, quartz is suitable for plasma discharge due to its low dielectric constant. Accordingly, even though there is a stark difference in thermal expansion between a dielectric and a Faraday shield, it is difficult to change the material of the dielectric to a different material. 
     SUMMARY 
     Embodiments of the inventive concept provide a Faraday shield for facilitating an increase in yield of a plasma source and usage and maintenance of the plasma source, and a substrate processing apparatus including the Faraday shield. 
     Embodiments of the inventive concept provide a Faraday shield for minimizing thermal expansion due to high temperature, and a substrate processing apparatus including the Faraday shield. 
     The technical problems to be solved by the inventive concept are not limited to the aforementioned problems, and any other technical problems not mentioned herein will be clearly understood from the following description by those skilled in the art to which the inventive concept pertains. 
     According to an embodiment, an apparatus for processing a substrate includes a plasma chamber, a coil electrode installed around the plasma chamber, and a Faraday shield provided between the coil electrode and the plasma chamber. The Faraday shield includes a cutout having a plurality of slots formed in a vertical direction along a periphery of the plasma chamber, an upper rim provided at the top of the cutout, and a lower rim provided at the bottom of the cutout. The upper rim and the lower rim have a thermal expansion reduction means configured to reduce a difference in thermal deformation between the upper and the lower rim and the cutout. 
     The thermal expansion reduction means may be implemented with open regions formed in the upper rim and the lower rim. 
     The open regions may be implemented with circular through-holes uniformly provided in the upper rim and the lower rim. 
     The open regions may be provided in a slot form in the upper rim and the lower rim. 
     The thermal expansion reduction means may be provided in a mesh form in the upper rim and the lower rim. 
     The open regions may account for 40% or less of the entire area of the upper rim and the lower rim. 
     According to an embodiment, a Faraday shield includes a body having a hollow cylindrical shape that is open at the top and the bottom. The body includes a cutout having a plurality of slots formed in a vertical direction, an upper rim provided at the top of the cutout, and a lower rim provided at the bottom of the cutout. The upper rim and the lower rim have a thermal expansion reduction means configured to reduce a difference in thermal deformation between the upper and the lower rim and the cutout. 
     The thermal expansion reduction means may be implemented with open regions formed in the upper rim and the lower rim. 
     The open regions may be implemented with circular through-holes uniformly provided in the upper rim and the lower rim. 
     The open regions may be provided in a slot form in the upper rim and the lower rim. 
     The open regions may be formed in the upper rim and the lower rim in an oblique direction. 
     The thermal expansion reduction means may be provided in a mesh form in the upper rim and the lower rim. 
     The open regions may account for  40 % or less of the entire area of the upper rim and the lower rim. 
     According to an embodiment, an apparatus for processing a substrate includes a housing that provides a processing space, a substrate support member that is disposed in the housing and that supports the substrate, and a plasma supply unit provided over the housing. The plasma supply unit includes a process gas supply port provided at the plasma supply unit and connected with a process gas supply tube that supplies a process gas, a plasma chamber having a discharge space formed therein, an antenna that surrounds the plasma chamber and applies plasma to the discharge space, and a Faraday shield provided between the antenna and the plasma chamber. The Faraday shield includes a cutout having a plurality of slots formed in a vertical direction along a periphery of the plasma chamber, an upper rim provided at the top of the cutout, and a lower rim provided at the bottom of the cutout. The upper rim and the lower rim have a thermal expansion reduction means configured to reduce a difference in thermal deformation between the upper and the lower rim and the cutout. 
     The open regions may be implemented with circular through-holes. 
     The open regions may be provided in an oblique slot form. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The above and other objects and features will become apparent from the following description with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified, and wherein: 
         FIGS. 1, 2A, and 2B  are views for explaining problems of a Faraday shield in the related art; 
         FIG. 3  is a schematic plan view illustrating substrate processing equipment according to an embodiment of the inventive concept; 
         FIG. 4  is a schematic side sectional view illustrating a process chamber according to an embodiment of the inventive concept; 
         FIG. 5  is a view illustrating a Faraday shield mounted on a plasma chamber; 
         FIG. 6  is a plan view of the Faraday shield illustrated in  FIG. 5 ; 
         FIG. 7  is a table showing changes in length and diameter of the Faraday shield depending on temperature; and 
         FIGS. 8 to 10  are views illustrating various modified examples of the Faraday shield. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the inventive concept will be described in more detail with reference to the accompanying drawings. The inventive concept may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the inventive concept will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. In the drawings, the dimensions of components are exaggerated for clarity of illustration. 
       FIG. 3  is a schematic plan view illustrating substrate processing equipment according to an embodiment of the inventive concept. 
     Referring to  FIG. 3 , the substrate processing equipment  1  has an equipment front end module (EFEM)  20  and a processing module  30 . The equipment front end module  20  and the processing module  30  are arranged in one direction. Hereinafter, the direction which the equipment front end module  20  and the processing module  30  are arranged is referred to as the first direction  11 , and the direction perpendicular to the first direction  11  when viewed from above is referred to as the second direction  12 . 
     The equipment front end module  20  has a load port  10  and a transfer frame  21 . The load port  10  is disposed at the front of the equipment front end module  20  in the first direction  11 . The load port  10  has a plurality of supports  6 . The supports  6  are arranged in a row in the second direction  12 , and carriers  4  (e.g., cassettes, FOUPs, or the like) containing substrates W to be processed and completely processed substrates W are located on the supports  6 . The substrates W to be processed and the completely processed substrates W are received in the carriers  4 . The transfer frame  21  is disposed between the load port  10  and the processing module  30 . The transfer frame  21  includes an index robot  25  that is disposed inside the transfer frame  21  and that transfers the substrates W between the load port  10  and the processing module  30 . The index robot  25  moves along a transport rail  27  in the second direction  12  to transfer the substrates W between the carriers  4  and the processing module  30 . 
     The processing module  30  includes a load-lock chamber  40 , a transfer chamber  50 , a plurality of process chambers  60 , and a controller  70 . 
     The load-lock chamber  40  is disposed adjacent to the transfer frame  21 . For example, the load-lock chamber  40  may be disposed between the transfer chamber  50  and the equipment front end module  20 . The load-lock chamber  40  provides a space in which the substrates W to be processed stand by before transferred to the process chambers  60  or a space in which the completely processed substrates W stand by before transferred to the equipment front end module  20 . 
     The transfer chamber  50  is disposed adjacent to the load-lock chamber  40 . The transfer chamber  50  has a polygonal body when viewed from above. The load-lock chamber  40  and the plurality of process chambers  60  are disposed on the exterior of the body along the periphery of the body. The body has, in sidewalls thereof, passages (not illustrated) through which the substrates W enter or exit the body, and the passages connect the transfer chamber  50  and the load-lock chamber  40  or the process chambers  60 . Doors (not illustrated) are provided for the respective passages to open/close the passages and hermetically seal the interior of the body. A transfer robot  53  that transfers the substrates W between the load-lock chamber  40  and the process chambers  60  is disposed in the interior space of the transfer chamber  50 . The transfer robot  53  transfers the unprocessed substrates W standing by in the load-lock chamber  40  to the process chambers  60 , or transfers the completely processed substrates W to the load-lock chamber  40 . Furthermore, the transfer robot  53  transfers the substrates W between the process chambers  60  to sequentially or simultaneously provide the substrates W to the plurality of process chambers  60 . 
     The process chambers  60  may be disposed around the transfer chamber  50 . The plurality of chambers  60  may be provided. In the process chambers  60 , processes are performed on the substrates W. The process chambers  60  process the substrates W transferred from the transfer robot  53  and provide the completely processed substrates W to the transfer robot  53 . The processes performed in the respective process chambers  60  may differ from one another. The process performed by each of the process chambers  60  may be one of processes of manufacturing a semiconductor device or a display panel using the substrate W. 
     The substrates W processed by the equipment have a comprehensive meaning including a substrate used to manufacture a semiconductor device, a substrate used to manufacture a flat panel display (FPD), and a substrate used to manufacture an object having a circuit pattern formed on a thin film thereof. Examples of the substrates W include a silicon wafer, a glass substrate, an organic substrate, and the like. 
       FIG. 4  is a schematic side sectional view illustrating a process chamber according to an embodiment of the inventive concept. The process chamber is a substrate processing apparatus that processes a surface of a substrate W with plasma. 
     Referring to  FIG. 4 , the process chamber  60  may include a process unit  100 , an exhaust unit  200 , and a plasma supply unit  300 . 
     The process unit  100  is a space in which the substrate W is processed. The process unit  100  may include a housing  110 , a substrate support member  120 , and a baffle  130 . 
     The housing  110  provides a processing space  111  in which a substrate processing process is performed. The substrate support member  120  is provided in the processing space  111 , and the substrate W to be processed is placed on an upper surface of the substrate support member  120 . The substrate W enters and exits the housing  110  through an opening. The opening may be opened and closed by an opening/closing member such as a door (not illustrated). 
     The substrate support member  120  supports the substrate W. The substrate support member  120  includes a support plate  121  and a support shaft  122 . The support plate  121  is located in the processing space  111  and has a circular plate shape. The support plate  121  is supported by the support shaft  122 . The substrate W is placed on an upper surface of the support plate  121 . 
     The baffle  130  is located over the support plate  121 . The baffle  130  may be electrically connected to an upper wall of the housing  110 . The baffle  130  may have a circular plate shape and may be disposed parallel to the upper surface of the substrate support member  120 . The baffle  130  may be formed of anodized aluminum. The baffle  130  has through-holes  131  formed therein. The through-holes  131  may be formed on concentric circumferences at predetermined intervals to uniformly supply radicals. Plasma diffused in a diffusion space  341  is introduced into the processing space  111  through the through-holes  131 . For example, at this time, charged particles such as electrons or ions may be confined in the baffle  130 , and neutral particles, such as oxygen radicals, which have no electrical charge may be supplied to the substrate W through the through-holes  131 . Furthermore, the baffle  130  may be grounded to form a passage through which electrons or ions move. 
     A lower baffle  140  is provided on a lower side of the process unit  100 . The lower baffle  140  may be provided around the support plate  121 . The lower baffle  140  may have a shape similar to that of the baffle  130 . The lower baffle  140  may adjust the time during which plasma remains in the processing space  111 . Reaction by-products passing through the lower baffle  140  are discharged outside the process unit  100  through an exhaust port  201 . 
     The exhaust unit  200  includes the exhaust port  201  and a depressurizing pump  210 . The exhaust port  201  is connected with the depressurizing pump  210  that pumps the reaction by-products to adjust the pressure in the process unit  100 . 
     The exhaust port  201  is connected with an exhaust hole formed in the bottom of the housing  110 . The exhaust port  201  provides a passage through which plasma and reaction by-products staying in the housing  110  are discharged to the outside. The exhaust port  201  is connected to an exhaust tube  203 . The exhaust tube  203  is connected to the depressurizing pump  210 . The exhaust port  210  may be provided around the support plate  121 . 
     The plasma supply unit  300  is located over the process unit  100  and over the housing  110 . The plasma supply unit  300  is separate from the process unit  100  and is provided outside the process unit  100 . The plasma supply unit  300  generates plasma from a process gas and supplies the plasma into the processing space  111  of the process unit  100 . 
     The plasma supply unit  300  may include a plasma chamber  310 , a process gas supply tube  320 , a power supply member  330 , a diffusion member  340 , and a Faraday shield  400 . 
     The plasma chamber  310  has a discharge space  310 a formed therein. An upper end of the plasma chamber  310  is hermetically sealed by a process gas supply port  315 . The process gas supply port  315  is connected with the process gas supply tube  320 . The process gas is a reaction gas for generation of plasma. The reaction gas is supplied into the discharge space  310   a  through the process gas supply port  315 . For example, the reaction gas may include difluoromethane (CH 2 F 2 ), nitrogen (N 2 ), and oxygen (O 2 ). Selectively, the reaction gas may further include a different type of gas such as tetrafluoromethane (CF 4 ). 
     The power supply member  330  supplies RF power to the discharge space  310   a.  The power supply member  330  may include an antenna  331  and a power source  332 . The antenna  331  is an inductively coupled plasma (ICP) antenna and has a coil shape. The antenna  331  is wound around the plasma chamber  310  a plurality of times. The antenna  331  is wound around a region of the plasma chamber  310  that corresponds to the discharge space  310 a. One end of the antenna  331  is connected with the power source  332 , and an opposite end of the antenna  331  is grounded. 
     A source part including the antenna  331  and the plasma chamber  310  is provided as one module surrounded by a first plate  311 , a second plate  312 , and a third plate  313 . The plasma chamber  310  may be formed of a dielectric (e.g., ceramic, quartz, or the like). The first plate  311 , the second plate  312 , and the third plate  313  may be formed of a metallic material. 
     The power source  332  supplies an RF current to the antenna  331 . The RF power supplied to the antenna  331  is applied to the discharge space  310   a.  An induced electric field is formed in the discharge space  310 a by the RF current, and the process gas supplied into the discharge space  310 a obtains energy required for ionization from the induced electric field and is converted into a plasma state. 
     The structure of the power supply member  330  is not limited to the above-described embodiment, and various structures for generating plasma from the process gas may be used. 
     A lower end of the plasma chamber  310  is connected with the diffusion member  340 . The diffusion member  340  is located between the plasma chamber  310  and the housing  110 . The diffusion member  340  hermetically seals an open upper surface of the housing  110 , and the housing  110  and the baffle  130  are coupled to a lower end of the diffusion member  340 . The diffusion space  341  is formed inside the diffusion member  340 . The diffusion space  341  connects the discharge space  310 a and the processing space  111  and serves as a passage through which plasma generated in the discharge space  310 a is supplied into the processing space  111 . 
       FIG. 5  is a view illustrating the Faraday shield mounted on the plasma chamber.  FIG. 6  is a plan view of the Faraday shield illustrated in  FIG. 5 .  FIG. 7  is a table showing changes in length and diameter of the Faraday shield depending on temperature. 
     Referring to  FIGS. 4 to 7 , the Faraday shield  400  shields part of an electric field applied into the discharge space  310 a by power supplied to the antenna  331 . The Faraday shield  400  is located between the plasma chamber  310  and the antenna  331  and surrounds a side surface of the plasma chamber  310 . The length of the Faraday shield  400  in an up/down direction corresponds to the distance from an upper end to a lower end of a region surrounding a side surface of the discharge space  310 a of the antenna  331 . The Faraday shield  400  may be grounded through the housing  110 . Selectively, the Faraday shield  400  may be directly connected to a separate ground line. The Faraday shield  400  is formed of a metallic material to shield the electric field. For example, the Faraday shield  400  may be formed of an aluminum (Al) material. 
     The Faraday shield  400  may be divided into an upper rim  420 , a lower rim  430 , and a cutout  410  between the upper rim  420  and the lower rim  430 . The cutout  410  includes a plurality of slots  412  formed in a vertical direction along the periphery of the plasma chamber  310 . The upper rim  420  may be provided at the top of the cutout  410 , and the lower rim  430  may be provided at the bottom of the cutout  410 . 
     The upper rim  420  may include a thermal expansion reduction means for reducing a difference in thermal deformation between the upper rim  420  and the cutout  410 , and the lower rim  430  may include a thermal expansion reduction means for reducing a difference in thermal deformation between the lower rim  430  and the cutout  410 . The thermal expansion reduction means may be implemented with open regions  422  and  432  formed in the upper rim  420  and the lower rim  430 . The open regions  422  and  432  preferably account for  40 % or less of the entire area of the upper rim  420  and the lower rim  430 . The differences in thermal deformation may be minimized as the areas of the open regions  422  and  432  are increased. 
     As described above, by lowering metal filling rates at the upper rim  420  and the lower rim  430  that are irrelevant to electromagnetic interference shielding, the Faraday shield  400  has a structure in which the entire length is the same, but an actual expansion rate of the same material is low even though thermal expansion occurs. 
     Referring to  FIGS. 7 and 2A , comparing the Faraday shield in the related art that has a filling rate of 100% and the Faraday shield of the inventive concept that has a relatively low filling rate, it can be seen that even though temperature rises, the expansion rate (change) is significantly low and when the Faraday shield of the inventive concept is applied to an actual plasma source, durability and production yields are improved. 
       FIGS. 8 to 10  are views illustrating various modified examples of the Faraday shield. For convenience, upper rims are not illustrated in  FIGS. 8 to 10 . Open regions may have various shapes (a circular shape, a quadrilateral shape, a triangular shape, and the like) capable of decreasing filling rates of rims. 
     As illustrated in  FIG. 8 , open regions formed in an upper rim  420  and a lower rim  430  of a Faraday shield  400   a  may have an oblique slot shape. 
     As illustrated in  FIG. 9 , open regions formed in an upper rim  420  and a lower rim  430  of a Faraday shield  400   b  may have a through-hole shape. 
     As illustrated in  FIG. 10 , thermal expansion reduction means of a Faraday shield  400 c may be provided in a mesh form in an upper rim  420  and a lower rim  430 . 
     According to the embodiments of the inventive concept, the Faraday shield and the substrate processing apparatus including the same may facilitate an increase in yield of the plasma source and usage and maintenance of the plasma source. 
     Effects of the inventive concept are not limited to the above-described effects, and any other effects not mentioned herein may be clearly understood from this specification and the accompanying drawings by those skilled in the art to which the inventive concept pertains. 
     The above description exemplifies the inventive concept. Furthermore, the above-mentioned contents describe exemplary embodiments of the inventive concept, and the inventive concept may be used in various other combinations, changes, and environments. That is, variations or modifications can be made to the inventive concept without departing from the scope of the inventive concept that is disclosed in the specification, the equivalent scope to the written disclosures, and/or the technical or knowledge range of those skilled in the art. The written embodiments describe the best state for implementing the technical spirit of the inventive concept, and various changes required in specific applications and purposes of the inventive concept can be made. Accordingly, the detailed description of the inventive concept is not intended to restrict the inventive concept in the disclosed embodiment state. In addition, it should be construed that the attached claims include other embodiments. 
     While the inventive concept has been described with reference to embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the inventive concept. Therefore, it should be understood that the above embodiments are not limiting, but illustrative.