Patent Publication Number: US-11646184-B2

Title: Substrate processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 U.S.C. § 119 to U.S. Patent Application No. 62/942,046 filed on Nov. 29, 2019, in the United States Patent and Trademark Office, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     One or more embodiments relate to a substrate processing apparatus, and more particularly, to a substrate processing apparatus having an improved exhaust structure. 
     2. Description of Related Art 
     In a substrate processing apparatus, a reaction gas introduced into a reaction space is exhausted to the outside through an exhaust space. However, some of the reaction gas is introduced into the bottom of a heating block, specifically the bottom of a reactor, on which a susceptor such as a substrate mounting portion is mounted. In particular, when a heterogeneous gas is supplied, reaction by-products are generated in a lower space of a chamber, and these reaction by-products become contaminants of a processing substrate and lower the yield of a device. In addition, when a highly corrosive cleaning gas is used to remove the reaction by-products, there is a problem that chamber components are damaged and consequently the life of the substrate processing apparatus is shortened. 
     In order to prevent a problem that the reaction gas supplied to the reaction space flows into the bottom of the reactor, gas is supplied from the bottom of the reactor. This gas is also called a filling gas because it fills the bottom of the reactor, and an inert gas such as Ar or N 2  is generally used. The filling gas balances the pressure between a reaction space on the substrate mounting portion and a lower space of the reactor to prevent the reaction gas from entering the lower space of the reactor. A substrate processing apparatus configuration using such a filling gas is disclosed in US Patent Publication No. 2018-0155836. 
     SUMMARY 
     One or more embodiments include a substrate processing apparatus capable of minimizing the effect of a filling gas on the processing of a substrate when using the filling gas to achieve a pressure balance between a reaction space and a lower space of a reactor. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure. 
     According to one or more embodiments, a substrate processing apparatus includes a substrate supporting unit; a processing unit on the substrate supporting unit; and an exhaust unit connected to a reaction space between the substrate supporting unit and the processing unit, wherein a first gas in the reaction space is transmitted to the exhaust unit through a first channel, a second gas in a lower space below the substrate supporting unit is transmitted to the exhaust unit through a second channel, and the first channel and the second channel may be joined to each other below the exhaust unit. 
     According to an example of the substrate processing apparatus, the exhaust unit may further include: a partition wall defining the side of the reaction space; an outer wall parallel to the partition wall; and a connecting wall extending to connect the partition wall to the outer wall, wherein a joining point at which the first channel and the second channel are joined to each other may be below the partition wall. 
     According to an example of the substrate processing apparatus, the substrate processing apparatus may further include a flow control ring disposed to surround the substrate supporting unit, wherein the first gas in the reaction space may be transmitted to the exhaust unit through a first surface of the flow control ring, and the second gas in the lower space below the substrate supporting unit may be transmitted to the exhaust unit through a second surface of the flow control ring. 
     According to another example of the substrate processing apparatus, the flow control ring may be disposed to overlap at least a portion of the exhaust unit below the exhaust unit. 
     According to another example of the substrate processing apparatus, the substrate processing apparatus may further include an outer ring disposed to surround the flow control ring, wherein the first channel may be between the exhaust unit and the flow control ring, and the second channel may be between the outer ring and the flow control ring. 
     According to another example of the substrate processing apparatus, the substrate processing apparatus may further include a support configured to support the processing unit and the exhaust unit, and the outer ring may be between the exhaust unit and the support. 
     According to another example of the substrate processing apparatus, the substrate supporting unit may be configured to be vertically movable, and the flow control ring may be configured to move up and down with the vertical movement of the substrate supporting unit. 
     According to another example of the substrate processing apparatus, a corner portion adjacent the joining point of the outer ring may include a first curved structure. 
     According to another example of the substrate processing apparatus, one corner portion of the exhaust unit may include a second curved structure, and the joining point may be between the first curved structure and the second curved structure. 
     According to another example of the substrate processing apparatus, the flow control ring may include: a first portion disposed to overlap at least a portion of the substrate supporting unit; and a second portion extending from the first portion along the side of the substrate supporting unit. 
     According to another example of the substrate processing apparatus, the flow control ring may further include a third portion extending from the second portion to overlap at least a portion of the exhaust unit. 
     According to another example of the substrate processing apparatus, the flow control ring may include: a first portion disposed to overlap at least a portion of the outer ring; and a second portion extending from the first portion along the side of the substrate supporting unit. 
     According to another example of the substrate processing apparatus, the substrate supporting unit may be configured to be vertically movable, and the flow control ring may be slid against the outer ring by a pushing force of the substrate supporting unit as the substrate supporting unit moves up and down. 
     According to another example of the substrate processing apparatus, the first portion of the flow control ring may include an uneven structure, and by the uneven structure, the second channel may be formed between the first portion of the flow control ring and the outer ring. 
     According to another example of the substrate processing apparatus, the second portion of the flow control ring may have a surface inclined with respect to the substrate supporting unit. 
     According to one or more embodiments, a substrate processing apparatus includes: a substrate supporting unit; a processing unit on the substrate supporting unit; an exhaust unit connected to a reaction space between the substrate supporting unit and the processing unit; and a ring disposed below the exhaust unit to overlap at least a portion of the exhaust unit, wherein a first gas in the reaction space may be transmitted to the exhaust unit through a first surface of the ring, and a second gas in a lower space below the substrate supporting unit may be transmitted to the exhaust unit through a second surface of the ring. 
     According to an example of the substrate processing apparatus, the first gas and the second gas may meet each other outside the reaction space. 
     According to one or more embodiments, a substrate processing apparatus includes: a substrate supporting unit; a processing unit on the substrate supporting unit; and an exhaust unit connected to a reaction space between the substrate supporting unit and the processing unit, wherein a first gas in the reaction space and a second gas in a lower space below the substrate supporting unit may meet each other outside the reaction space. 
     According to an example of the substrate processing apparatus, the first gas and the second gas may meet each other at a point below the exhaust unit located outside the reaction space. 
     According to another example of the substrate processing apparatus, the exhaust unit may include a partition wall defining a side of the reaction space, and the first gas and the second gas may be configured to meet each other outside a surface of the partition wall contacting the reaction space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIGS.  1  and  2    are views of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIGS.  3  to  5    are views of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIG.  6    is a view of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIGS.  7  and  8    are views of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIGS.  9  to  11    are views of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIGS.  12  to  14    are views of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIG.  15    is a view of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIG.  16    is a partial enlarged view of the substrate processing apparatus of  FIG.  15   ; 
         FIG.  17    is a view of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIG.  18    is a view of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIG.  19    is a partial enlarged view of the substrate processing apparatus of  FIG.  18   ; 
         FIGS.  20  and  21    are views of a substrate processing apparatus according to embodiments of the inventive concept; 
         FIG.  22    is a view for explaining a ring self-alignment process according to rising of a heating block; and 
         FIG.  23    is a view of the ring shown in  FIG.  22   . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes”, “comprises” and/or “including”, “comprising” used herein specify the presence of stated features, integers, steps, processes, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, processes, members, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various members, components, regions, layers, and/or sections, these members, components, regions, layers, and/or sections should not be limited by these terms. These terms do not denote any order, quantity, or importance, but rather are only used to distinguish one component, region, layer, and/or section from another component, region, layer, and/or section. Thus, a first member, component, region, layer, or section discussed below could be termed a second member, component, region, layer, or section without departing from the teachings of embodiments. 
     Embodiments of the disclosure will be described hereinafter with reference to the drawings in which embodiments of the disclosure are schematically illustrated. In the drawings, variations from the illustrated shapes may be expected as a result of, for example, manufacturing techniques and/or tolerances. Thus, the embodiments of the disclosure should not be construed as being limited to the particular shapes of regions illustrated herein but may include deviations in shapes that result, for example, from manufacturing processes. 
       FIGS.  1  and  2    are views of a substrate processing apparatus according to embodiments of the inventive concept.  FIG.  1    shows a substrate processing apparatus and a portion (cross section of a portion where an opening of an exhaust unit  120  is not formed) of the substrate processing apparatus.  FIG.  2    shows a substrate processing apparatus and another portion (cross section of a portion where an opening OP of the exhaust unit  120  is formed) of the substrate processing apparatus. 
     Referring to  FIGS.  1  and  2   , the substrate processing apparatus may include a partition  100 , a substrate supporting unit  150 , a processing unit  110 , the exhaust unit  120 , and at least one ring R. The substrate processing apparatus may include a reaction space  51  and an exhaust space  55  connected to the reaction space  51 . 
     The partition  100  is a chamber for receiving the substrate supporting unit  150 , which may also be referred to as a chamber. In an embodiment, a reactor including the reaction space  51  is referred to as an inner chamber, and the entire structure of the substrate processing apparatus surrounding a plurality of reactors (e.g., four reactors) may be referred to as an outer chamber. An exhaust line  18  may be provided in the partition  100 . In some embodiments, the exhaust line  18  may be formed to extend along the inside of a side wall of the partition  100 . In an embodiment, the substrate processing apparatus includes a first surface and a second surface adjacent the first surface, and the exhaust line  18  may extend along an edge between the first surface and the second surface. In additional embodiments, the exhaust line  18  may be formed to extend along the inside of a lower wall of the partition  100 . 
     The processing unit  110  may be located on the substrate supporting unit  150  configured to support a substrate. The reaction space  51  may be defined between the substrate supporting unit  150  and the processing unit  110 . The processing unit  110  may serve as a first lid that defines an upper surface of the reaction space  51 . In other words, the first lid on the substrate supporting unit may include at least one processing unit  110 . 
     The processing unit  110  may include members that perform appropriate functions depending on a function of the substrate processing apparatus. For example, when a substrate processing apparatus performs a deposition function, the processing unit  110  may include a reactant supplier (e.g., a showerhead assembly). In another embodiment, when the reactor performs a polishing function, the processing unit  110  may include a polishing pad. 
     The processing unit  110  may be a conductor and may be used as an electrode for generating plasma. That is, the processing unit  110  may serve as one electrode for generating plasma. The processing unit  110  in this manner (the manner in which the processing unit  110  is used as an electrode) is hereinafter referred to as a gas supply electrode. 
     The substrate supporting unit  150  may be configured to provide an area where an object to be processed (not shown) such as a semiconductor or a display substrate is seated. The substrate supporting unit  150  may be supported by a driver (not shown) capable of vertical and/or rotational movement. Further, the substrate supporting unit  150  may be a conductor and may be used as an electrode for generating plasma (i.e., an opposite electrode of a gas supply electrode). 
     The exhaust unit  120  may be located between the processing unit  110  and a support TLD. The exhaust unit  120  may extend to surround the reaction space  51 . Gas in the reaction space  51  may be exhausted to an exhaust port  13  through the exhaust unit  120 . 
     In an embodiment, the exhaust unit  120  may serve as a second lid that defines a side surface of the reaction space  51 . The second lid including the exhaust unit  120  may include the exhaust space  55  connected to the reaction space  51 . Therefore, the exhaust unit  120  may provide the exhaust space  55 . Further, the exhaust unit  120  may provide a space in which the processing unit  110  is received. When the processing unit  110  is received in the space, the processing unit  110  may be in contact with the exhaust unit  120 . 
     The exhaust unit  120  may include a partition wall W between the reaction space  51  and the exhaust space  55 . A first surface (e.g., an outer surface) of the partition wall W may define the reaction space  51  and a second surface of the partition wall W (i.e., an inner surface as a surface facing the first surface) may define the exhaust space  55 . For example, the reaction space  51  may be defined by the first surface side of the partition wall W, an upper surface of the substrate supporting unit  150 , and a lower surface of the processing unit  110  which is the first lid. In other words, a side of the reaction space  51  may be defined by the partition wall W of the exhaust unit  120 . 
     The exhaust unit  120  may provide a portion of a space for the object to be processed. For example, when the substrate processing apparatus performs a deposition function, the reaction space  51  for deposition may be defined by the exhaust unit  120 . Further, the exhaust space  55  may be defined inside the exhaust unit  120 . The reaction space  51  may be connected to the exhaust port  13  through the exhaust space  55  of the exhaust unit  120 . In more detail, gas in the reaction space  51  may be exhausted to the exhaust port  13  through a first channel C 1 , the exhaust space  55 , and the opening OP. 
     In an example, the exhaust unit  120  may include a connecting wall C and the outer wall O extending from the partition wall W. The outer wall O of the exhaust unit  120  is disposed in parallel with the partition wall W and may contact the support TLD. The opening OP may be formed in the outer wall O, and the exhaust unit  120  and the exhaust port  13  may be connected to each other through the opening OP. The connecting wall C of the exhaust unit  120  may extend to connect the partition wall W to the outer wall O. The connecting wall C may provide a contact surface with the processing unit  110 . The processing unit  110 , which is the first lid, and the exhaust unit  120 , which is the second lid, may be in contact with each other by the contact surface. 
     The support TLD may contact the exhaust unit  120  to support the processing unit  110  and the exhaust unit  120 . The support TLD may be supported by the partition  100 . As described above, the support TLD may serve as a top lid which is supported by the partition  100  to cover an outer chamber while supporting the processing unit  110  as the first lid and the exhaust unit  120  as the second lid. 
     The support TLD may be between the partition  100  and a lid (e.g., the second lid including the exhaust unit  120 ). Also, the support TLD may be between the partition  100  and the exhaust port  13 . The support TLD may include a path P connecting the exhaust port  13  to the exhaust line  18  of the partition  100 . In additional embodiments, a sealing member (not shown) may be between the support TLD and the partition. The sealing member may extend along a circumference of the path P or the exhaust line  18 , thereby preventing leakage of gas moving from the path P to the exhaust line  18 . 
     The at least one ring R may be disposed to surround the substrate supporting unit  150 . For example, the at least one ring R may include a flow control ring FCR. The flow control ring FCR may be below the exhaust unit  120 . In more detail, the flow control ring FCR may be arranged to overlap at least a portion of the exhaust unit  120  in the vertical direction. Due to this overlapping arrangement, the first channel C 1  can be formed between the flow control ring FCR and the exhaust unit  120 . As a result, a first gas (e.g., source gas and/or reaction gas) in the reaction space  51  may be transmitted to the exhaust space  55  of the exhaust unit  120  through a first surface (e.g., upper surface) of the flow control ring FCR. 
     In more detail, the partition wall W of the exhaust unit  120  may provide the first channel C 1  connecting the reaction space  51  to the exhaust space  55 . For example, the first channel C 1  may be formed between the exhaust unit  120  and the at least one ring R, in particular between the exhaust unit  120  and the flow control ring FCR. The first channel C 1  may function as a channel between the reaction space  51  and the exhaust space  55 . Therefore, the reaction space  51  and the exhaust space  55  may communicate with each other through the first channel C 1  provided by the partition wall W. 
     The flow control ring FCR may be apart from the support TLD to form a second channel C 2 . The flow control ring FCR may move laterally on the substrate supporting unit  150  (i.e., slide against the substrate supporting unit  150 ). By adjusting a width or spacing of the second channel C 2  through the lateral movement, a pressure balance between the reaction space  51  and a lower space  57  (i.e., an inner space of the outer chamber) under the substrate supporting unit  150  may be controlled. 
     A second gas introduced into the lower space  57  through the filling gas inlet  114  may be transmitted to the exhaust space  55  through the second channel C 2 . In more detail, the second gas in the lower space  57  may be transmitted to the exhaust space  55  of the exhaust unit  120  through a second surface (e.g., a side surface) of the flow control ring FCR. 
     The support TLD may provide the second channel C 2  connecting the lower space  57  to the exhaust space  55 . For example, the second channel C 2  may be formed between the support TLD and at least one ring R, particularly between the support TLD and the flow control ring FCR. The second channel C 2  may function as a channel between the lower space  57  and the exhaust space  55 . Therefore, the lower space  57  and the exhaust space  55  may communicate with each other through the second channel C 2  provided by the support TLD. 
     As such, the first gas in the reaction space  51  and the second gas in the lower space  57  may move through different channels (i.e., the first channel C 1  and the second channel C 2 ). The first gas and the second gas moved to different channels may meet each other at a point other than the reaction space  51 . For example, the first gas and the second gas may meet each other outside the reaction space  51 . In more detail, the first gas and the second gas may meet each other below the exhaust unit  120  located outside the reaction space  51 . 
     In an example, the first gas and the second gas may be transmitted from the respective channels C 1  and C 2  to the exhaust unit  120  through a joining point I below the exhaust unit  120 . The joining point I may be disposed outside the partition wall W. In more detail, the joining point I may be disposed outside a surface of the partition wall W that is in contact with the reaction space  51  among side surfaces of the partition wall W. In an example, the joining point I may be below the partition wall W of the exhaust unit  120 . In another example, the joining point I may be the exhaust space  55  in the exhaust unit  120 . 
     In either example, the first gas of the reaction space  51  and the second gas of the lower space  57  will not meet each other in the reaction space  51 . Therefore, a collision of the first gas (e.g., a reaction gas) and the second gas (e.g., a filling gas) in a substrate edge area may be prevented. In other words, by configuring the substrate processing apparatus such that the first gas in the reaction space  51  and the second gas in the lower space  57  meet each other outside a surface of the partition wall contacting the reaction space  51 , a turbulent flow that may occur in the substrate edge area may be prevented. 
     In addition, the first channel C 1  through which the first gas in the reaction space  51  passes and the second channel C 2  through which the second gas in the lower space  57  passes may be separated from each other by at least one ring R. Here, the separation of channels means that the two channels extend without encountering each other. Therefore, the first channel C 1  and the second channel C 2  separated by the at least one ring R, in particular the flow control ring FCR, may each extend without encountering each other. The first channel C 1  and the second channel C 2  separated by the flow control ring FCR may encounter at the joining point I outside the flow control ring FCR and be transmitted to the exhaust space  55 . 
     As such, according to embodiments of the inventive concept, it can be minimized that a filling gas supplied from a lower portion of a reactor affects the process on a substrate. Furthermore, according to embodiments of the inventive concept, by allowing gas to be divided and exhausted through at least one ring structure such as a flow control ring, rapid gas exhaust may be achieved. 
       FIGS.  3  to  5    are views of a substrate processing apparatus according to some embodiments of the inventive concept. In more detail,  FIG.  3    shows a portion (e.g., exhaust lines  18  and  28 , a connection port CP, an external path EC connected to an external pump, etc.) of the substrate processing apparatus excluding a lid (i.e., a processing unit and an exhaust unit) and an exhaust port.  FIG.  4    is a view of  FIG.  3    viewed from a first direction, and  FIG.  5    is a view of  FIG.  3    viewed from a second direction. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIGS.  3  to  5   , exhaust lines  18  and  28  are formed in the partition  100 . The exhaust lines  18  and  28  are connected to the external path EC through the connection port CP and the external path EC is connected to a main exhaust path  211 . Therefore, gas in a reaction space and gas in a lower space are exhausted to an exhaust pump EP via exhaust ports  13  and  23 , the exhaust lines  18  and  28 , the external path EC, and the main exhaust path  211 . Although not shown in the drawings, each of the exhaust ports  13  and  23  is provided with a flow control unit according to embodiments of the inventive concept. 
     As shown in  FIG.  4   , two reactors R 1   a  and R 1   b  in a first direction use inner exhaust lines  18   a  and  18   b , and the remaining two reactors in a direction opposite to the first direction use other inner exhaust lines  28   a  and  28   b . The two inner exhaust lines  18  and  28  are connected to the external path EC through connection ports CP and CP′, respectively. The external path EC may be implemented in one configuration or in a plurality of configurations. 
     As a result, it can be seen that the four reactors use at least one of external paths EC and EC′, the main exhaust path  211 , and the exhaust pump EP. An isolation valve  210  may be added to the main exhaust path  211 . Therefore, the exhaust pump EP may be protected from the outside atmosphere by the isolation valve  210  during a maintenance period. Further, a pressure control valve (e.g., a throttle valve) may be added to the main exhaust path  211 . The external path EC may be fixed so as not to move in close contact with a lower surface of the partition  100  of an outer chamber. In an alternative embodiment, the two inner exhaust lines  18  and  28  may be connected to each other within a bottom wall of the partition  100  of the outer chamber and directly connected to the main exhaust path  211 , without the external path EC. 
     Referring again to  FIG.  3   , the first external path EC connected to the first connection port CP may extend below the partition  100  towards a first corner portion C 1  of the outer chamber. In addition, the second external path EC′ connected to the second connection port CP′ (not shown) may extend below the partition  100  towards a second corner portion C 2  of the outer chamber. The exhaust pump EP may be arranged on one surface of the substrate processing apparatus, for example, corresponding to the center between the first corner portion C 1  and the second corner portion C 2 . The first external path EC may extend from the portion extending to the first corner portion C 1  to the exhaust pump EP. Also, the second external path EC′ may extend from the portion extending to the second corner portion C 2  to the exhaust pump EP. 
       FIG.  6    is a view of a substrate processing apparatus according to embodiments of the inventive concept. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
       FIG.  6    shows an upper surface of a multi-reactor chamber  311 . A plurality of reactors RT are arranged in the chamber  311  and one side of each of the reactors RT is connected to an exhaust port  313 .  FIG.  6    shows that each reactor RT is connected to each exhaust port  313 , and the exhaust port  313  is disposed asymmetrically with respect to the center of each reactor RT. 
     A plurality of exhaust lines (not shown) may be formed in a partition of the chamber  311 . For example, the chamber  311  may be rectangular in shape, and the plurality of exhaust lines may include a first exhaust line, a second exhaust line, a third exhaust line, and a fourth exhaust line. In some embodiments, the first to fourth exhaust lines may be arranged corresponding to four vertices of the rectangle. 
     The chamber  311  may include a first reactor, a second reactor, a third reactor, and a fourth reactor. Each reactor may include a substrate supporting unit, at least one ring, a processing unit, an exhaust unit, and an exhaust port. 
     In more detail, the first reactor may include a first substrate supporting unit (not shown) accommodated in the partition of the chamber  311 , at least one first ring surrounding the first substrate supporting unit, a first processing unit  312  on the first substrate supporting unit, a first exhaust unit  314  connected to a first reaction space between the first substrate supporting unit and the first processing unit  312 , and a first exhaust port  313  connected to at least a portion of the first exhaust unit  314 . As described above, the gas in the first reaction space and the gas in the lower space below the first substrate supporting unit may meet each other outside the first reaction space. In addition, the gas in the first reaction space and the gas in the lower space below the first substrate supporting unit may be transmitted to the first exhaust unit  314  through different channels. The different channels may be separated by the at least one first ring. The different channels may also extend along different surfaces of the at least one first ring. 
     The second reactor may include a second substrate supporting unit (not shown) accommodated in the partition of the chamber  311 , at least one second ring surrounding the second substrate supporting unit, a second processing unit  312  on the second substrate supporting unit, a second exhaust unit  314  connected to a second reaction space between the second substrate supporting unit and the second processing unit  312 , and a second exhaust port  313  connected to at least a portion of the second exhaust unit  314 . As described above, gas in the second reaction space and gas in a lower space below the second substrate supporting unit may meet each other outside the second reaction space. In addition, the gas in the second reaction space and the gas in the lower space below the second substrate supporting unit may be transmitted to the second exhaust unit  314  through different channels. The different channels may be separated by the at least one second ring. The different channels may also extend along different surfaces of the at least one second ring. 
     The third reactor may include a third substrate supporting unit (not shown) accommodated in the partition of the chamber  311 , at least one third ring surrounding the third substrate supporting unit, a third processing unit  312  on the third substrate supporting unit, a third exhaust unit  314  connected to a third reaction space between the third substrate supporting unit and the third processing unit  312 , and a third exhaust port  313  connected to at least a portion of the third exhaust unit  314 . As described above, the gas in the third reaction space and the gas in the lower space below the third substrate supporting unit may meet each other outside the third reaction space. In addition, the gas in the third reaction space and the gas in the lower space below the third substrate supporting unit may be transmitted to the third exhaust unit  314  through different channels. The different channels may be separated by the at least one third ring. The different channels may also extend along different surfaces of the at least one third ring. 
     The fourth reactor may include a fourth substrate supporting unit (not shown) accommodated in the partition of the chamber  311 , at least one fourth ring surrounding the fourth substrate supporting unit, a fourth processing unit  312  on the fourth substrate supporting unit, a fourth exhaust unit  314  connected to a fourth reaction space between the fourth substrate supporting unit and the fourth processing unit  312 , and a fourth exhaust port  313  connected to at least a portion of the fourth exhaust unit  314 . As described above, the gas in the fourth reaction space and the gas in the lower space below the fourth substrate supporting unit may meet each other outside the fourth reaction space. In addition, the gas in the fourth reaction space and the gas in the lower space below the fourth substrate supporting unit may be transmitted to the fourth exhaust unit  314  through different channels. The different channels may be separated by the at least one fourth ring. The different channels may also extend along different surfaces of the at least one fourth ring. 
       FIGS.  7  and  8    are views of a substrate processing apparatus according to embodiments of the inventive concept. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIGS.  7  and  8   , at least one ring R may include at least one of the flow control ring FCR and an outer ring OR. The outer ring OR may be disposed to surround the flow control ring FCR. Thus, the flow control ring FCR may be between the substrate supporting unit  150  and the outer ring OR. 
     The first channel C 1  through which the first gas of the reaction space  51  moves may be between the exhaust unit  120  and the flow control ring FCR. The second channel C 2  through which the second gas of the lower space  57  moves may be between the outer ring OR and the flow control ring FCR. In this way, the first channel C 1  and the second channel C 2  are separated by the flow control ring FCR, and since the separated first and second channels C 1  and C 2  may be joined to each other at the joining point I outside the reaction space  51  and connected to the exhaust space  55 , stable process progression may be achieved. 
     The flow control ring FCR may be implemented in an ‘L’ shape, and for this purpose, the flow control ring FCR may include a first portion FCR- 1  and a second portion FCR- 2 . The first portion FCR- 1  may be defined as a portion overlapping at least a portion of the substrate supporting unit  150 . In an alternative embodiment, the first portion FCR- 1  of the flow control ring FCR may be disposed to be slidable on the substrate supporting unit  150 . 
     In some embodiments, the substrate supporting unit  150  may be configured to be vertically movable. When the substrate supporting unit  150  is raised, the flow control ring FCR may move up and down with the vertical movement of the substrate supporting unit  150  by the first portion FCR- 1  of the flow control ring FCR disposed to overlap the substrate supporting unit  15 . 
     The second portion FCR- 2  may be defined as a portion extending in a vertical direction from the first portion FCR- 1  along the side of the substrate supporting unit  150 . In addition, the second portion FCR- 2  of the flow control ring FCR may extend in a horizontal direction (circumferential direction) along the side of the support TLD. In some embodiments, the second portion FCR- 2  may extend to overlap at least a portion of the exhaust unit  120 . Although not shown in the drawings, in another embodiment, the flow control ring FCR may further include a third portion (see FCR- 3  in  FIG.  18   ) extending from the second portion FCR- 2  to overlap at least a portion of the exhaust unit  120 . 
     The outer ring OR may be on the support TLD. In more detail, the outer ring OR may be between the exhaust unit  120  and the support TLD. The outer ring OR may be disposed to be slidable on the support TLD. The flow control ring FCR may be apart from the outer ring OR to form the second channel C 2  and a pressure balance between the reaction space  51  and an inner space of the outer chamber (i.e., the lower space  57 ) may be controlled by adjusting an interval of the second channel C 2 . 
     The outer ring OR may include a curved structure at a corner portion adjacent to the joining point I of the first channel C 1  and the second channel C 2 . Such a curved structure may accelerate the flow of gas around the curved structure. In an alternative embodiment, the exhaust unit  120  may also include a curved structure at the corner portion adjacent to the joining point I. In this case, the joining point I will be between the curved structure of the outer ring OR and the curved structure of the exhaust unit  120 . 
     By introducing the curved structure of the outer ring OR, a second gas moving through the second channel C 2  may be accelerated to the exhaust unit  120  with a laminar flow along the curved structure. Therefore, the collision at the joining point I of the first gas moving through the first channel C 1  and the second gas moving through the second channel C 2  may be reduced. As a result, the exhaust of gas around the joining point I may be promoted by the curved structure. 
       FIGS.  9  to  11    are views of a substrate processing apparatus according to embodiments of the inventive concept. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIGS.  9  and  10   , the flow control ring FCR may include a first portion FCR- 1 ′ and the second portion FCR- 2 . The first portion FCR- 1 ′ of the flow control ring FCR may be defined as a portion overlapping at least a portion of the support TLD. Furthermore, the first portion FCR- 1 ′ may extend to overlap at least a portion of the substrate supporting unit  150 . Therefore, the flow control ring FCR may be implemented in a ‘T’ shape. 
     Although  FIGS.  9  and  10    show the first portion FCR- 1 ′ configured to overlap the support TLD and the substrate supporting unit  150 , the first portion FCR- 1 ′ may be configured to overlap only the support TLD (see  FIG.  21   ). In this case, the flow control ring FCR will be implemented in an ‘L’ shape. 
     The second portion FCR- 2  of the flow control ring FCR may extend from the first portion FCR- 1 ′ in a vertical direction along the side of the substrate supporting unit  150 . In addition, the second portion FCR- 2  of the flow control ring FCR may extend in a horizontal direction (circumferential direction) along the side of the support TLD. That is, the second portion FCR- 2  of the flow control ring FCR may extend between the substrate supporting unit  150  and the support TLD. 
     By the configuration of the flow control ring FCR, the first channel C 1  and the second channel C 2  may be separated from each other in the reaction space  51 . That is, the first channel C 1  formed between the exhaust unit  120  and the flow control ring FCR and the second channel C 2  formed between the flow control ring FCR and the support TLD (or the outer ring OR (in  FIG.  12   ) on the support) may extend without encountering each other in the reaction space  51 . 
     In some embodiments, as shown in  FIGS.  9  and  10   , the first channel C 1  and the second channel C 2  may be separated by the flow control ring FCR and extend to the exhaust unit  120 . In this case, the joining point of a first gas passing through the first channel C 1  and a second gas passing through the second channel C 2  will be the exhaust space  55  outside the reaction space  51 . 
     The substrate supporting unit  150  may be configured to be vertically movable. For example, the substrate supporting unit  150  may move downward, and the substrate supporting unit  150  may load/unload a substrate in the lower space  57 . In addition, the substrate supporting unit  150  may move upward, and processing for the substrate may be performed in the reaction space  51 . As the substrate supporting unit  150  moves up and down, the flow control ring FCR may be in surface contact with the substrate supporting unit  150 . 
     For example, as the substrate supporting unit  150  moves up and down, a lower surface of the first portion FCR- 1 ′ configured to overlap the substrate supporting unit  150  of the flow control ring FCR and an upper surface of a step of the substrate supporting unit  150  may contact each other. As a result, the reaction space  51  and the lower space  57  may communicate with the exhaust space  55  through the first channel C 1  and the second channel C 2 , respectively, separated by the flow control ring FCR. 
     In some embodiments, the first portion FCR- 1 ′ of the flow control ring FCR may include an uneven structure Y. In more detail, the uneven structure Y may be formed in the first portion FCR- 1 ′ of the flow control ring FCR overlapping at least a portion of the upper surface of the step of the support TLD. By the uneven structure Y, the second channel C 2  may be formed between the first portion FCR- 1 ′ of the flow control ring FCR and the support TLD. 
     In an alternative embodiment, the first portion FCR- 1 ′ of the flow control ring FCR may not include an uneven structure. In this case, as the substrate supporting unit  150  moves up and down, the flow control ring FCR may also move up and down. As the flow control ring FCR move up and down, the second channel C 2  may be generated between the first portion FCR- 1 ′ and the upper surface of the step of the support TLD. In either case, the first gas in the reaction space may be transmitted to the exhaust unit through a first surface of the flow control ring FCR, and the second gas in the lower space may be transmitted to the exhaust unit through a second surface of the flow control ring FCR. 
     In some embodiments, the flow control ring FCR may move up and down with the vertical movement of the substrate supporting unit  150 . Furthermore, the flow control ring FCR may slide with respect to the support TLD together with the vertical movement of the substrate supporting unit  150 . In this case, the exhaust efficiency of the first channel C 1  and/or the exhaust efficiency of the second channel C 2  may vary depending on the degree of vertical movement of the substrate supporting unit  150 . 
     An exemplary configuration of the flow control ring FCR used in the embodiments of  FIGS.  9  and  10    is shown in  FIG.  11   . The flow control ring FCR having the first portion FCR- 1 ′ and the second portion FCR- 2  may have a shape corresponding to that of a substrate to be processed. For example, when the substrate to be processed is a circular wafer, the flow control ring may be implemented in a circle having a larger diameter. As shown in  FIG.  11   , the flow control ring FCR may be implemented to have a ‘T’ shaped cross section. In addition, the first portion FCR- 1 ″ of the flow control ring FCR may have the uneven structure Y, and the second gas in the lower space may be transmitted to the exhaust unit through the uneven structure Y. 
       FIGS.  12  to  14    are views of a substrate processing apparatus according to embodiments of the inventive concept. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIGS.  12  and  13   , the substrate processing apparatus may further include the outer ring OR disposed to surround the flow control ring FCR. In this case, the first portion FCR- 1 ′ of the flow control ring FCR may overlap at least a portion of the outer ring OR. In addition, the first channel C 1  may be between the exhaust unit  120  and the flow control ring FCR, and the second channel C 2  may be between the outer ring OR and the flow control ring FCR. The outer ring OR may be on the support TLD. 
     The flow control ring FCR may be configured to be slidable on the outer ring OR. For example, a lower surface of the flow control ring FCR or an upper surface of the outer ring OR may be surface treated to have relatively low roughness (e.g., roughness of 0.4 or less). 
     The second portion FCR- 2  of the flow control ring FCR, that is, a portion extending in a vertical direction along the side of the substrate supporting unit  150  from the first portion FCR- 1 ′ may have a surface that is inclined with respect to the substrate supporting unit  150  (see  FIGS.  12  and  13   ). For example, a side surface of the substrate supporting unit  150  may extend in a vertical direction, and a side surface of the second portion FCR- 2  of the flow control ring FCR may extend in a direction inclined with respect to the vertical direction. In another example, the side surface of the second portion FCR- 2  of the flow control ring FCR may extend in a vertical direction, and the side surface of the substrate supporting unit  150  may extend in a direction inclined with respect to the vertical direction. 
     As such, by configuring the flow control ring FCR to be slidable on the outer ring OR and by configuring the side surface of the second portion FCR- 2  of the flow control ring FCR and the side surface of the substrate supporting unit  150  to be inclined with respect to each other, the flow control ring FCR may move in a second direction as the substrate supporting unit  150  moves in a first direction. In more detail, as the substrate supporting unit  150  moves in the first direction, the substrate supporting unit  150  may contact the flow control ring FCR. The flow control ring FCR may move in the second direction (e.g., may slide in a horizontal direction) by a force generated as the substrate supporting unit  150  continues to move in the first direction while in contact with the flow control ring FCR. 
     This force may be defined as a force by which the substrate supporting unit pushes the flow control ring FCR. Since the flow control ring FCR is slidable on the outer ring OR, as the substrate supporting unit  150  moves up and down, the pushing force causes the flow control ring FCR to slide against the outer ring OR. 
     An exemplary configuration of the flow control ring FCR used in the embodiments of  FIGS.  12  and  13    is shown in  FIG.  14   . As described above, the flow control ring FCR may include the first portion FCR- 1 ′ extending to overlap the substrate supporting unit  150  and the outer ring OR and the second portion FCR- 2  extending in a vertical direction from the first portion. Meanwhile, the second portion FCR- 2  may be configured to have an inclined surface. For example, an inclined surface may be formed such that an inner diameter of one end portion close to the first portion FCR- 1 ′ is less than an inner diameter of another end portion far from the first portion FCR- 1 ′. 
       FIG.  15    is a view of a substrate processing apparatus according to embodiments of the inventive concept.  FIG.  16    is an enlarged view of portion A in  FIG.  15   . The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIG.  15   , a substrate (not shown) is mounted on a heating block  79 . A heating block driver  710  in a lower space may vertically move the heating block  79 . Loading and unloading of the substrate may proceed by the vertical movement of the heating block  79 . 
     Gas supplied to a reactor is introduced into a reaction space  711  on the heating block  79  on which the substrate is seated (not shown) through a gas inlet  713  and a showerhead  72 . A process gas  716  is then exhausted after completion of substrate processing (e.g., deposition) using the gas (or during substrate processing). The process gas  716  is transmitted to an exhaust duct  74  through a space between a flow control ring  75  and the exhaust duct  74 . The process gas  716  transmitted to the exhaust duct  74  may be exhausted to an exhaust pump (not shown) through an exhaust port  73  and a reactor wall  71 . 
     When a gas  715  is introduced into the reaction space  711  through the gas inlet  713 , a filling gas  717  is introduced into a reactor lower space  712  through a filling gas inlet  714 . As shown in area A of  FIG.  15   , when the process gas  716  is exhausted into an exhaust space  76  in the exhaust duct  74 , the filling gas  717  is supplied to a separation space between the heating block  79  and the flow control ring  75 . By supplying the filling gas  717  to the separation space, the process gas  716  is blocked from being introduced into the reactor lower space  712 . In order to achieve the blocking, an adjustment operation may be performed to balance process pressure in a reaction space  711  and pressure in the reactor lower space  712  to which the filling gas  717  is supplied. 
     The filling gas  717  introduced into the separation space between the heating block  79  and the flow control ring  75  may reduce the exhaust efficiency. That is, since the filling gas  717  introduced into the separation space collides with the process gas  716  after the reaction, the exhaust efficiency may be reduced. Furthermore, such gas collisions occur at a substrate edge area. Thus, the gas collisions may affect the uniformity of a thin film to be treated. 
     In more detail, as shown in  FIG.  16    showing the case where the heating block  79  is raised to form the reaction space  711  for substrate processing, a collision may occur between the process gas  716  and the filling gas  717  moving through the space between the heating block  79  and the flow control ring  75 . This gas collision impedes a regular exhaust flow of the gas into the exhaust duct  74 . Due to this poor exhaust flow in the substrate edge area, the uniformity of a thin film in the substrate edge is degraded. Accordingly, the present invention seeks to disclose configurations and apparatus for minimizing the effect of a filling gas on the process in a reaction space. 
       FIG.  17    is a view of a substrate processing apparatus according to embodiments of the inventive concept. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIG.  17   , in order to prevent the filling gas  717  from the lower space and the process gas  716  from the reaction space  711  from directly colliding near the edge of a substrate (i.e., the edge of the heating block  79 ), a flow control ring  75  is placed at the edge of the heating block  79 . A first exhaust channel through which the process gas  716  travels is formed between the flow control ring  75  and the exhaust duct  74 , and a second exhaust channel through which the filling gas  717  travels is formed between the flow control ring  75  and an outer ring  718 . 
     Thus, as shown in  FIG.  17 ( b ) , the direct collision of the process gas  716  and the filling gas  717  around the substrate may be prevented. Furthermore, since a corner portion of the outer ring  718  has a curved structure, by a coanda effect, the filling gas  717  may be accelerated along the curved structure of the outer ring  718  constituting the second exhaust channel. The accelerated filling gas  717  may be efficiently exhausted into the exhaust space  76  of the exhaust duct  74  while forming a laminar flow. 
     In the meantime, the flow control ring  75  may move up and down together with the heating block  79 . In this case, the height of the first exhaust channel formed between the flow control ring  75  and the exhaust duct  74  may be adjusted according to the rising height of the heating block  79  and the flow control ring  75 . Therefore, the exhaust efficiency of the process gas  716  exhausted to the exhaust space  76  through the first exhaust channel may be controlled. 
     The flow control ring  75  seated on the heating block  79  may descend with the lowering of the heating block  79 . When the lowering of the heating block  79  continues for loading/unloading of a substrate to be processed, the flow control ring  75  may be separated from the heating block  79 , and the separated flow control ring  75  may be seated on a support member  750 . The support member  750  may be fixed below a chamber CH. In an alternative embodiment, the support member  750  may be configured to be detachable under the chamber CH. 
     When the heating block  79  is raised, the flow control ring  75  seated on the support member  750  may be seated on the heating block  79  again. Accordingly, as the heating block  79  moves up and down, the flow control ring  75  on the support member  750  is separated from the support member  750 , and the flow control ring  75  may move up and down together with the heating block  79 . 
       FIG.  18    is a view of a substrate processing apparatus according to embodiments of the inventive concept.  FIG.  19    is a partial enlarged view of the substrate processing apparatus of  FIG.  18   ; The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIG.  18   , the exhaust paths of the process gas  716  and the filling gas  717  are separated from each other. That is, a first exhaust channel through which the process gas  716  is exhausted and a second exhaust channel through which the exhaust gas is exhausted may be separated by the outer ring  718 . Thus, as shown in  FIG.  18 B , the process gas  716  is exhausted into the exhaust duct  74  through the first exhaust channel formed between the exhaust duct  74  and the outer ring  718  without collision with the filling gas  717 . The filling gas  717  is exhausted into the exhaust duct  74  through the second exhaust channel between a chamber wall (i.e., a support) and the outer ring  718  without collision with the process gas  716 . 
     The flow control ring  75  may include a first portion FCR- 1 ″ disposed to overlap at least a portion of a substrate supporting unit including the heating block  79 , the second portion FCR- 2  extending in a vertical direction from the first portion FCR- 1 ″ along the side of the substrate supporting unit, and the third portion FCR- 3  extending in a horizontal direction from the second portion FCR- 2  to overlap at least a portion of the outer ring  718 . 
     The flow control ring  75  is disposed at the edge of the heating block  79  and moves up and down together with the heating block  79 . When the heating block  79  rises to a substrate processing position, the flow control ring  75  and the outer ring  718  perform face sealing  719  to physically prevent a collision between a reaction gas and a filling gas. 
     In more detail, as the heating block  79  rises, a lower surface of the first portion FCR- 1 ″ may contact the heating block  79 , and an upper surface of the third portion FCR- 3  may be connected to a lower surface of the outer ring  718 . Thus, as the heating block  79  continues to rise, the flow control ring FCR may also rise through the first portion FCR- 1 ″, and the outer ring  718  may also rise through the third portion FCR- 3 . As the outer ring  718  is lifted by the accompanying ascent action, the second exhaust channel may be formed by being apart between a chamber wall CH (i.e. support) and the outer ring  718 . 
     When the heating block  79  descends, the lower surface of the outer ring  718  may contact the chamber wall CH (i.e. support) and the outer ring  718  may be seated on the chamber wall CH. Then, as the heating block  79  continues to descend, the flow control ring  75  seated on the heating block  79  may be separated from the heating block  79 , and a lower surface of the third portion FCR- 3  may contact the upper surface of the support member  750 . Thus, the flow control ring  75  separated from the heating block  79  will be seated on the support member  750 . 
     According to the embodiment of  FIG.  18   , unlike the embodiment of  FIG.  17   , the height of the first exhaust channel and the second exhaust channel may be determined according to the extent to which the flow control ring  75  lifts the outer ring  718 , that is, the ascending height of the heating block  79 . Therefore, it is possible to control the exhaust efficiency of the filling gas  717  or the process gas  716  and determine a lifting position of the heating block  79  for the optimal exhaust efficiency. 
     Meanwhile, in  FIG.  18 ( b ) , the side of the outer ring  718  may be apart from the side of the flow control ring  75 . In more detail, the second portion FCR- 2  of the flow control ring  75  and the outer ring  718  may be apart from each other to form a space. Due to this formed space, a blind spot  720  exists between the outer ring  718  and the flow control ring  75 . Since no filling gas is supplied to the blind spot, some of the process gas exhausted from a reaction space remains.  FIG.  19    is an enlarged view of an area around the blind spot  720  of  FIG.  18 ( b ) . 
     As shown in  FIG.  19   , in some embodiments, at least one of the exhaust duct  74  and the outer ring  718  may include a curved structure. The curved structure may be configured to facilitate evacuation of the process gas (e.g., reaction gas) located in the spaced space described above to the first exhaust channel. For example, the curved structure may have a certain radius of curvature. 
     Referring to  FIG.  19   , a reaction gas exhausted from a reaction space to the exhaust duct  74  is exhausted in approximately three forms. A flow in the form of “G 1 ” is exhausted directly into the exhaust space  76  (of  FIG.  18   ) through an exhaust channel between the outer ring  718  and the exhaust duct  74  from the reaction space. A flow in the form of “G 2 ” flows along an outer wall of the exhaust duct  74  and is accelerated near a curved surface L of the exhaust duct  74  and introduced into the exhaust channel. A flow in the form of “G 3 ” flows into the blind spot  720  and then flows back into the exhaust channel by a suction force in the exhaust space. Here, the flow in the form of “G 3 ” is accelerated near a curved surface L′ of the outer ring  718  to be introduced into the exhaust channel. That is, due to the curved structure of the outer ring  718 , it is possible to prevent residual gas and its turbulent flow in the blind spot, and the process gas may be exhausted and removed more quickly and smoothly. 
       FIG.  20    is a view of a substrate processing apparatus according to embodiments of the inventive concept. The substrate processing apparatus according to the embodiments may be a variation of the substrate processing apparatus according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein. 
     Referring to  FIG.  20   , the exhaust duct  74  may include a first curved structure D 1 , and the outer ring  718  may include a second curved structure D 2 . In this case, the joining point I of a first channel through which the process gas  716  is exhausted and a second channel through which the filling gas  717  is exhausted may be between the first curved structure D 1  of the exhaust duct  74  and the second curved structure D 2  of the outer ring  718 . As such, corners of the outer ring  718  and the exhaust duct  74  exposed to the exhaust channel are curved. Accordingly, exhaust of the filling gas  717  and the process gas  716  (e.g., reaction gas) may be accelerated along the curved surface of the outer ring  718  or the exhaust duct  74  by inducing a coanda effect. 
     In the embodiments of  FIGS.  18  to  20   , in order to smoothly and quickly exhaust the filling gas  717  and the process gas  716 , the corners of the exhaust duct and the outer ring that encounter gas are curved to induce the coanda effect. In order to achieve this object, the curvature of a curved surface may be preferably R 1 or more (i.e., the radius of curvature of 1 mm or more). 
     The technical features of the embodiments of  FIGS.  18  to  20    are as follows. 
     1. A gap connecting upper and lower spaces of a reactor is bypassed. That is, gas movement from an upper portion to a lower portion and gas movement from a lower portion to an upper portion may be blocked, and lower discharge may be suppressed by immediately discharging a lower gas. 
     2. A distance (i.e., a channel through which a filling gas in a lower space is exhausted) between the existing flow control ring and the heating block may be separated from a substrate to suppress process variations due to a lower gas. 
     3. A plasma confinement effect may be obtained by arranging a flow control ring on the side of a heating block, and a uniform and stable plasma process may be performed by concentrating plasma in a reaction space on a substrate. 
     4. A flow control ring disposed on the side of a heating block may move in accordance with vertical movement of the heating block. Thus, the width and volume of an exhaust channel formed between an exhaust duct and an outer ring and between the outer ring and a chamber wall may be controlled. 
     In the embodiments of  FIGS.  18  to  20    described above, an exhaust flow of gas is controlled through a structure in which a flow control ring is disposed on the side of a heating block (i.e., a structure in which a flow control ring is disposed to overlap a portion of a heating block in a vertical direction). On the other hand,  FIG.  21    illustrates a structure in which a flow control ring is disposed on an outer ring to overlap a portion of the outer ring. In this embodiment, an exhaust flow of gas is controlled through a structure that prevents a collision between a reaction gas and a filling gas around a heating block. 
     Referring to  FIG.  21   , a separation distance between the side of the heating block  79  and the flow control ring  75  is very narrow. For example, the separation distance may be configured to within 0.2 mm. Therefore, it is very difficult for the filling gas  717  to pass into a reaction space or for the process gas  716  to pass into a lower space. On the other hand, the flow control ring  75  and the outer ring  718  are apart from each other enough to allow gas to pass, thereby forming an exhaust channel of the filling gas  717 . 
     Thus, as shown in  FIG.  21   , the process gas  716  and the filling gas  717  do not collide with each other around the heating block, and may be exhausted into the exhaust space  76  through respective exhaust channels. In  FIG.  21   , the collision between the process gas  716  and the filling gas  717  is minimized by narrowing the separation distance between the side of the heating block  79  and the flow control ring  75  very much. However, this structure has another advantage that may facilitate self-alignment of the flow control ring  75  in the reaction space. For example, when the flow control ring  75  is asymmetrically disposed on an upper surface of the outer ring  718 , that is, when the center of symmetry of the inner diameter of the flow control ring  75  does not coincide with the center of the heating block  79 , as the heating block  79  rises, the heating block  79  makes a surface-contact with a portion of the inner surface of the flow control ring  75 , and thus a force is applied in a horizontal direction with respect to the flow control ring  75 . Accordingly, the center of symmetry of the inner diameter of the flow control ring  75  and the center of the heating block  79  may coincide. 
       FIG.  22    illustrates such a process.  FIG.  22    shows a process of self-alignment of the flow control ring  75  by the heating block  79 .
         First operation ( FIG.  22 ( a ) ): The heating block  79  rises.   Second operation ( FIG.  22 ( b ) ): The side of the heating block  79  and the inner side of the flow control ring  75  contact.   Third operation ( FIG.  22 ( c ) ): The movement of the flow control ring  75  is initiated while the heating block  79  continues to rise in contact with the flow control ring  75 . For example, the flow control ring  75  moves laterally (i.e., slides) against the outer ring  718  on an upper surface of a step of the outer ring  718  in surface contact.   Fourth operation ( FIG.  22 ( d ) ): As the heating block  79  continues to rise in contact with the flow control ring  75 , self-alignment of the flow control ring  75  proceeds.   Fifth operation ( FIG.  22 ( e ) ): The heating block  79  is raised to a substrate processing position and the self-alignment of the flow control ring  75  is completed.       

     A control method (especially the self-alignment of the flow control ring) of a substrate processing apparatus according to the embodiment of  FIG.  22    is particularly important in a high temperature process (e.g., a high temperature process above 500° C.). At high temperatures, due to thermal deformation of the heating block  79  and the flow control ring  75 , the width of a gap between the heating block  79  and the flow control ring  75  depends on the position on the side of the heating block  79  and the flow control ring  75 . Therefore, when the flow control ring  75  is fixed on the outer ring  718 , a filling gas or a reaction gas may be introduced into the gap at a specific position, which affects thin film uniformity around a substrate. 
     According to the embodiments of  FIG.  22   , by the self-alignment of the flow control ring  75  through the contact between the heating block  79  and the flow control ring  75 , deformation due to high temperature and consequent non-uniformity in process may be prevented. To maintain this structure, sidewalls of the flow control ring  75  and sidewalls of the outer ring  718  are spaced at regular intervals to facilitate alignment of the flow control ring  75  on the upper surface of the outer ring  718 . 
       FIG.  23    is a view of the flow control ring  75  used in  FIG.  22   . 
     Referring to  FIGS.  22  and  23   , a lower surface of the flow control ring  75 , that is, a portion of the flow control ring  75  in contact with the upper surface of the outer ring  718  has the uneven structure Y, which supports the flow control ring  75  on the outer ring  718  while providing an exhaust channel of a filling gas, for example, nitrogen (N 2 ). In addition, surface roughness of an inner surface of the flow control ring may be 0.4 or less so that the inner surface of the flow control ring  75  is in contact with the heating block  79 , slides by the weight of the flow control ring, and self-alignment proceeds by the sliding. 
     It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the following claims.