Patent Publication Number: US-11654458-B2

Title: Substrate-cleaning apparatus having tiltable roll brush

Description:
CROSS-REFERENCE TO THE RELATED APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2020-0060842 filed on May 21, 2020 in the Korean Intellectual Property Office, the subject matter of which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     1. Field 
     The inventive concept relates generally to substrate-cleaning apparatuses including a tiltable roll brush. 
     2. Description of the Related Art 
     Chemical mechanical polishing (CMP) may be performed on a wafer (or substrate) in order to shape the wafer or form a desired pattern on the wafer. Once CMP is completed, a cleaning process may be applied to the wafer in order to remove various contaminants (e.g., particles, residues, organic pollutants, etc.) remaining on a surface of the wafer as the result of the CMP. 
     Conventionally, the cleaning process has been performed by inserting the substrate between vertically arranged roll brushes. Once the wafer is properly seated (e.g., using a substrate support), and the roll brushes may rotate while moving up and down against the substrate to clean surface(s) of the substrate. While the roll brushes are rotating, the substrate may also be rotated by rollers mounted to the substrate support. However, because the roll brushes have fixed outer diameters, when the roll brushes and the substrate rotate at the same time, the frequency of contact between the substrate and the roll brushes gradually decreases towards the outer edge of the substrate. This outcome results in inefficient cleaning of the substrate edge as compared with the cleaning efficiency of the center of the substrate. 
     SUMMARY 
     Embodiments of the inventive concept provide a substrate-cleaning apparatus including a tiltable roll brush capable of efficiently cleaning the entirety of a substrate (e.g., both edge and center portions of a substrate). 
     A substrate-cleaning apparatus according to embodiments of the inventive concept may include; a roll brush coupled to a tilting arm, a support arm positioned on the tilting arm, a first spring and a second spring coupling the tilting arm to the support arm, a first air bag and a second air bag mounted between the tilting arm and the support arm, and a controller configured to adjust a first internal pressure of the first air bag and a second internal pressure of the second air bag, wherein the controller defines an inclination of the roll brush by adjusting a difference between the first internal pressure and the second internal pressure. 
     A substrate-cleaning apparatus according to embodiments of the inventive concept may include; roll brush coupled to a tilting arm, wherein the tilting arm includes a motor-coupling portion securing a motor, a support arm positioned on the tilting arm, a first air bag and a second air bag mounted between the tilting arm and the support arm, an upper bracket positioned between the first air bag and the second air bag and protruding from a bottom surface of the support arm, a lower bracket protruding from a top surface of the tilting arm, a pivot shaft inserted into the upper bracket and the lower bracket, and a controller configured to adjust a first internal pressure of the first air bag and a second internal pressure of the second air bag, wherein the controller defines an inclination of the roll brush by adjusting a difference between the first internal pressure and the second internal pressure. 
     A substrate-cleaning apparatus according to embodiments of the inventive concept may include; a roll brush, a motor configured to rotate the roll brush, a tilting arm including a bracket to support the roll brush and a motor-coupling portion to secure the motor, a driving shaft of the motor penetrating the motor-coupling portion to be connected to the roll brush, a support arm positioned on the tilting arm, a first air bag and a second air bag suspending the tilting arm from the support arm, a vertical shaft securing the support arm, an vertical adjustment driving unit coupled to the vertical shaft to vertically adjust the tilting arm and the support arm, a regulator connected to the first air bag and the second air bag, and a controller configured to control the regulator to adjust a first internal pressure of the first air bag and a second internal pressure of the second air bag, wherein the controller adjusts a difference between the first internal pressure and the second internal pressure to control an inclination of the tilting arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating a substrate-cleaning apparatus according to embodiments of the inventive concept. 
         FIG.  2    is a perspective view of a substrate-cleaning apparatus according to embodiments of the inventive concept. 
         FIG.  3    is a front view of  FIG.  2   . 
         FIG.  4    is a another view of the upper cleaning unit  110  of  FIG.  3   . 
         FIG.  5    is an enlarged perspective view of region P 1  shown in  FIG.  3   . 
         FIG.  6    is a further enlarged perspective view of  FIG.  5   . 
         FIGS.  7  and  8    are respective views illustrating a tilting operation of the brush-tilting unit according to embodiments of the inventive concept. 
         FIG.  9    is a perspective view illustrating a substrate-cleaning apparatus according to embodiments of the inventive concept. 
         FIG.  10    is an enlarged perspective view of region P 2  shown in  FIG.  9   . 
         FIG.  11    is an exploded perspective view of the tilting arm and the support arm of  FIG.  10   . 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the written description and drawings, like reference numbers and labels are used to denote like or similar elements and/or features. Throughout the written description certain geometric terms may be used to highlight relative relationships between elements, components and/or features with respect to certain embodiments of the inventive concept. Those skilled in the art will recognize that such geometric terms are relative in nature, arbitrary in descriptive relationship(s) and/or directed to aspect(s) of the illustrated embodiments. Geometric terms may include, for example: height/width; vertical/horizontal; top/bottom; higher/lower; closer/farther; thicker/thinner; proximate/distant; above/below; under/over; upper/lower; center/side; surrounding; between; overlay/underlay; etc. 
       FIG.  1    is a perspective view illustrating a substrate-cleaning apparatus according to embodiments of the inventive concept. 
     Referring to  FIG.  1   , the substrate-cleaning apparatus  10  may include support rollers  50  configured to support a substrate W and a pair of vertically-arranged roll brushes  111  and  211 . The substrate W may be transferred to a space between the roll brushes  111  and  211  by a substrate transfer unit. In this position the substrate W may be supported by the support rollers  50 , and as the support rollers  50  rotate in a desired direction, the substrate W will counterrotate rotate in an opposing direction. In conjunction with the rotation of the substrate W, the roll brushes  111  and  211  may rotate while in respective contact with top and bottom surfaces of the substrate W. As the roll brushes  111  and  211  respectively brush the top and bottom surfaces of the substrate W a cleaning solution and/or deionized water may be applied to the substrate W and/or the roll brushes  111  and  211 . 
       FIG.  2    is a perspective view of a substrate-cleaning apparatus according to embodiments of the inventive concept;  FIG.  3    is a front view of  FIG.  2   ; and  FIG.  4    is another view of the upper cleaning unit  110  of  FIG.  3   . 
     Referring to  FIGS.  2  and  3   , a substrate-cleaning apparatus  10   a  may include an upper cleaning unit  100 , a lower cleaning unit  200  and a connection unit  300 . The upper cleaning unit  100  and the lower cleaning unit  200  may be vertically aligned and mechanically coupled to the connection unit  300 . The upper cleaning unit  100  and the lower cleaning unit  200  may be used to clean the top and/or bottom surface(s) of a substrate inserted therebetween. 
     Referring to  FIGS.  2 ,  3  and  4   , the upper cleaning unit  100  may include a brush-tilting unit  110 , an air unit  120  and an upper vertical adjustment unit  130 . The brush-tilting unit  110  may be located under the air unit  120 , and may be suspended from the air unit  120 . The upper vertical adjustment unit  130  may be laterally disposed in relation to the brush-tilting unit  110  and the air unit  120 . The air unit  120  may be securely coupled to the upper vertical adjustment unit  130 . In this manner, the brush-tilting unit  110  may be connected to the upper vertical adjustment unit  130  via the air unit  120 . That is, the upper vertical adjustment unit  130  may be used to adjust (or move) the vertically position of the air unit  120 . As the air unit  120  is vertically moved, the brush-tilting unit  110  follows. Hence, a distance (or gap) between the brush-tilting unit  110  and the lower cleaning unit  200  may be adjusted through movement of the brush-tilting unit  110  using the air unit  120 . 
     In the illustrated example of  FIG.  2   , the brush-tilting unit  110  includes a roll brush  111 , a shaft  112 , a tilting arm  116  and a motor  117 . The brush-tilting unit  110  may further include a front-end engagement part  113 , a rear-end engagement part  114 , and a coupling part  115 . 
     The roll brush  111  may surround the shaft  112 . A number of protrusions may be formed on the surface of the roll brush  111  in a regular arrangement. The roll brush  111  may be formed of a porous, sponge (or resin) material capable of holding and distributing liquid(s). 
     The shaft  112  may penetrate the roll brush  111  and be rotatably coupled to the tilting arm  116 . For example, the roll brush  111  may be coupled to the tilting arm  116  via the front-end engagement part  113 . The front-end engagement part  113  may be rotatably coupled to the tilting arm  116 . The shaft  112  may be connected to the driving shaft of the motor  117 . For example, the shaft  112  may be coupled to the driving shaft of the motor  117  via the rear-end engagement part  114  and the coupling part  115 . When the driving shaft of the motor  117  rotates, the coupling part  115  and the rear-end engagement part  114  may transfer the rotational force to the shaft  112 , thereby rotating the shaft  112  and the roll brush  111 . The roll brush  111  may be brought into contact with the surface of the substrate while rotating, thereby applying pressure to remove contaminants (e.g., particles) from the surface of the substrate. 
     The tilting arm  116  may include a body portion  116   a,  a bracket  116   b  and a motor-coupling portion  116   c.  The body portion  116   a  may be disposed above the roll brush  111 , and may have a bar shape that extends laterally (e.g., in a longitudinal direction) from the roll brush  111 . The body portion  116   a  may be mechanically coupled to the air unit  120 , and may be suspended from the air unit  120 . The bracket  116   b  may be connected to one end of the body portion  116   a,  and may rotatably support the shaft  112  and the roll brush  111  via the front-end engagement part  113 . The motor-coupling portion  116   c  may be bent from the opposite end of the body portion  116   a  to extend downwards. The motor  117  may be coupled to and secured to the outer side of the motor-coupling portion  116   c.  Referring to  FIG.  4   , the driving shaft of the motor  117  may penetrate the motor-coupling portion  116   c,  and may be connected to the shaft  112  and to the roll brush  111  via the coupling part  115  and the rear-end engagement part  114 . 
     Referring again to  FIGS.  2 ,  3  and  4   , the motor  117  may be supported by the motor-coupling portion  116   c,  and may be spaced apart from the air unit  120  or the upper vertical adjustment unit  130 . Accordingly, when the tilting arm  116  is tilted, the entirety of the motor  117  may be tilted together with the tilting arm  116 , thereby avoiding the application of an eccentric load to the driving shaft of the motor  117  during the tilting operation. As noted above, the routine application of an eccentric lad to the driving shaft of the motor  117  tends to shorten the lifespan of the motor. In this regard, the “tilting” of the tilting arm  116  may be understood as a relative elevation (e.g., higher or lower) of one end (e.g., a distal end) of the tilting arm  116  to another end (e.g., a proximate end) of the tilting arm  116  relative to the connection unit  300 . 
     The air unit  120  may include a support arm  121 , a spring  122  and an air bag  123 . The air unit  120  may further include a nozzle  126 . The support arm  121  may be located above the tilting arm  116 . The support arm  121  is directly secured to the upper vertical adjustment unit  130 , and may be moved by the upper vertical adjustment unit  130 . The support arm  121  may include a body  121   a  and a plate  121   b . The body  121   a  may have a bar shape, and the plate  121   b  may be a flat panel. The body  121   a  may be coupled to an upper portion of one surface of the plate  121   b.  An engagement portion may be formed on a lower portion of the opposite surface of the plate  121   b.  The engagement portion may be secured to an upper vertical shaft  131 , whereby the support arm  121  may be coupled to the upper vertical shaft  131 . 
     The spring  122  may be mounted between the support arm  121  and the body portion  116   a  of the tilting arm  116 , and may elastically connect the tilting arm  116  to the support arm  121 . The upper end of the spring  122  may be secured to the bottom surface of the support arm  121 , the lower end of the spring  122  may be secured to the top surface of the body portion  116   a,  and the distance between the support arm  121  and the tilting arm  116  may be maintained at a predetermined level by the elastic force of the spring  122 . The spring  122  may include a first spring  122   a  and a second spring  122   b.  The first spring  122   a  and the second spring  122   b  may be spaced horizontally apart from each other at a predetermined interval, and may support the brush-tilting unit  110  so that the brush-tilling unit  110  is oriented horizontally. The intermediate point between the first spring  122   a  and the second spring  122   b  may be a point that vertically overlaps the center of gravity of the brush-tilting unit  110 . 
     The air bag  123  may be vertically mounted between the support arm  121  and the body portion  116   a  of the tilting arm  116 , and may be laterally disposed between the first spring  122   a  and the second spring  122   b.  In some embodiments, the first spring  122   a  and the second spring  122   b  may be located between a pair of air bags  123 . The upper end of the air bag  123  may be secured to the bottom surface of the support arm  121 , the lower end of the air bag  123  may be secured to the top surface of the body portion  116   a,  and the tilting arm  116  may be stably suspended from the support arm  121  via the spring  122  and the air bag  123 . 
     The air bag  123  may include a first air bag  123   a  and a second air bag  123   b.  The first air bag  123   a  and the second air bag  123   b  may be laterally spaced apart at a defined interval. The first air bag  123   a  may be located further away from one end of the roll brush  111  than the second air bag  123   b.  The intermediate point between the first air bag  123   a  and the second air bag  123   b  may be a point that vertically overlaps the center of gravity of the brush-tilting unit  110 . Thus, the first spring  122   a,  the first air bag  123   a,  the second air bag  123   b  and the second spring  122   b  may be laterally disposed along the tilting arm  116  in parallel with the extension direction of the roll brush  111 . 
     In some embodiments, the first spring  122   a  may be disposed close to the first air bag  123   a,  and the second spring  122   b  may be disposed close to the second air bag  123   b . The distance between the first spring  122   a  and the first air bag  123   a  may be substantially the same as the distance between the second spring  122   b  and the second air bag  123   b.  The first air bag  123   a  and the second air bag  123   b  may be spaced apart from each other by a distance that is longer than the distance between the first spring  122   a  and the first air bag  123   a.  Since the spring  122  provides elastic force to the tilting arm  116  in the state of being disposed close to one side of the air bag  123 , the vertical movement and/or the tilting operation of the brush-tilting unit  110  due to expansion and/or contraction of the air bag  123  may be precisely controlled. Further, since the first air bag  123   a  and the second air bag  123   b  are spaced apart, the brush-tilting unit  110  may be stably supported, and the inclination of the brush-tilting unit  110  may be finely adjusted by expansion and/or contraction of the first air bag  123   a  and/or the second air bag  123   b.    
     The nozzle  126  may be mounted on the support arm  121 . The nozzle  126  may be connected to a gas tank via a gas supply line, and a pneumatic control module  410  may be connected to the gas supply line. A controller  430  may be provided to adjust a first internal pressure to the first air bag  123   a  and a second internal pressure to the second air bag  123   b . The controller  430  may be connected to a pneumatic control module  410  (or alternately, a pair of pneumatic control modules  410 ) and may control the pneumatic control module  410  in order to adjust the pressure of the gas supplied from the gas tank to the air bag  123  through the gas supply line and the nozzle  126 . 
     The upper vertical adjustment unit  130  may include an upper vertical shaft  131 , an upper vertical adjustment coupling part  132 , and an upper vertical adjustment driving unit  133 . The upper vertical adjustment coupling part  132  and the upper vertical adjustment driving unit  133  may be mechanically coupled to the upper vertical shaft  131 . The upper vertical shaft  131  may be coupled to and secured to the upper portion of the connection unit  300 , and may support the air unit  120  and the brush-tilting unit  110 . 
     A rotary body, mechanically coupled to the upper vertical shaft  131 , may be rotated by the upper vertical adjustment driving unit  133 , and may move vertically along the upper vertical shaft  131 . The air unit  120  coupled to the upper vertical shaft  131  and the brush-tilting unit  110  suspended from the air unit  120  may move vertically together according to the vertical movement of the rotary body. 
     The lower cleaning unit  200  may include a brush unit  210  and a lower vertical adjustment unit  230 , and may not include an air unit  120 , in contrast with the upper cleaning unit  100 . The brush unit  210  may include components that are the same as and/or similar to those of the brush-tilting unit  110  of the upper cleaning unit  100 . For example, the brush unit  210  may include a roll brush  211 , a holder  216 , and a motor  217 . The holder  216  may be disposed below the roll brush  211 , and may rotatably support the roll brush  211 . The motor  217  may be secured to the outer side of the holder  216 , and the driving shaft of the motor  217  may penetrate the holder  216  to be connected to the roll brush  211 . The holder  216  may be directly coupled to the lower vertical adjustment unit  230 , and the lower vertical adjustment unit  230  may move the roll brush  211  vertically via the holder  216 . 
       FIG.  5    is an enlarged perspective view of region P 1  shown in  FIG.  3   , and  FIG.  6    is a further enlargement of certain aspects of  FIG.  5   . 
     Referring to  FIGS.  5  and  6   , the tilting arm  116  may further include a lower protruding portion  116   d  protruding from the top surface of the body portion  116   a.  The support arm  121  may further include an upper protruding portion  121   c  protruding from the bottom surface of the body  121   a.  The lower protruding portion  116   d  may include a first lower protruding portion  116   d - 1  and a second lower protruding portion  116   d - 2 , and the upper protruding portion  121   c  may include a first upper protruding portion  121   c - 1  and a second upper protruding portion  121   c - 1 . The upper protruding portion  121   c  and the lower protruding portion  116   d  may be disposed so as to vertically overlap each other. That is, the upper protruding portion  121   c  and the lower protruding portion  116   d  may be vertically aligned with each other. The air bag  123   a  or  123   b  may be interposed between the lower protruding portion  116   d  and the upper protruding portion  121   c.  The lower end of the air bag  123   a  or  123   b  may be secured to the upper end of the lower protruding portion  116   d,  and the upper end of the air bag  123   a  or  123   b  may be secured to the lower end of the upper protruding portion  121   c.  Specifically, the first air bag  123   a  may be interposed between the first lower protruding portion  116   d - 1  and the first upper protruding portion  121   c - 1 , and the second air bag  123   b  may be interposed between the second lower protruding portion  116   d - 2  and the second upper protruding portion  121   c - 2 . 
     The air unit  120  may further include a lower plate  124  penetrating the air bag  123  and an upper plate  125  positioned within an air region AR in the air bag  123 . The air region AR may be a space formed in the air bag  123 , in which the gas supplied for expansion and/or contraction of the air bag  123  stays. A horizontal hole may be formed below the air region AR so as to penetrate the air bag  123  horizontally. The lower plate  124  may be inserted into the horizontal hole so as to penetrate the air bag  123 . One end and the opposite end of the lower plate  124  penetrating the air bag  123  may protrude from respective sides of the air bag  123 , and may be securely coupled to the lower protruding portion  116   d  of the tilting arm  116 . For example, the lower plate  124  may be secured to the lower protruding portion  116   d  by inserting a screw through the lower plate  124  and fastening the screw to the lower protruding portion  116   d.  Since the lower plate  124  is secured to the lower protruding portion  116   d,  the lower portion of the air bag  123  may also be secured to the lower protruding portion  116   d.    
     Referring to  FIG.  6   , the upper plate  125  may be mounted in the air region AR. For example, the upper plate  125  may be coupled to the support arm  121 , and may be suspended downwards from the upper protruding portion  121   c  of the support arm  121  using a screw. The upper portion of the air bag  123  may be interposed between the upper plate  125  and the upper protruding portion  121   c.  The upper plate  125  may support the upper portion of the air bag  123  to fix the upper end of the air bag  123  to the upper protruding portion  121   c . A hole  125   h  may be formed in the upper plate  125 , and gas may flow in and/or out (hereafter, “in/out”) of the air region AR in the air bag  123  through the hole  125   h.    
     The support arm  121  may include a through-hole  121   d  vertically penetrating the body  121   a  and the upper protruding portion  121   c.  The nozzle  126  may be mounted in the upper portion of the through-hole  121   d,  and the lower portion of the through-hole  121   d  may communicate with the air region AR in the air bag  123 . Accordingly, the gas supplied from the gas tank through the pneumatic control module  410  may flow into or out of the air region AR in the air bag  123  through the nozzle  126  and the through-hole  121   d.    
       FIGS.  7  and  8    are additional views further illustrating the tilting operation of the brush-tilting unit according to embodiments of the inventive concept. 
     Referring to  FIG.  7   , the air bag  123  may include a flexible material, and may increase/decrease (or expand/contract) in volume depending on the internal pressure (i.e. the internal pressure of the air region AR illustrated in  FIG.  6   ). For example, the air bag  123  may be made of a flexible material such as silicon or rubber. In response to the applied pressure, the air bag  123  may vertically expand/contract. That is, when the air bag  123  expands, the vertical height of the air bag  123  increases, and when the air bag  123  contracts, the vertical height of the air bag  123  decreases. The air bag  123  may also expand/contract horizontally in response to the applied pressure. 
     The controller  430  may be used to further define an inclination of the roll brush  111  by creating (or adjusting) a difference in internal pressure between the first air bag  123   a  and the second air bag  123   b.  The controller  430  may tilt the tilting arm  116  by creating a difference between the first internal pressure applied to the first air bag  123   a  and the second internal pressure applied to the second air bag  123   b.  In this manner, the entirety of the brush-tilting unit  110  may be tilted as the tilting arm  116  is tilted. That is, the roll brush  111  and the motor  117 , which are secured to the tilting arm  116 , may be tilted together with the tilting arm  116 . The controller  430  may adjust the inclination of the roll brush  111  to change the contact pressure applied to the edge region of the substrate W, and may adjust the rotational stiffness of the roll brush  111  with respect to the substrate W. 
     In some embodiments, the controller  430  may control the pneumatic control module  410  connected to the first air bag  123   a  and/or the second air bag  123   b,  such that the first internal pressure of the first air bag  123   a  is greater than the second internal pressure of the second air bag  123   b.  Accordingly, the volume (and vertical height) of the first air bag  123   a  may become greater than that of the second air bag  123   b,  and the roll brush  111  may be tilted such that one end is higher than the other end. 
     The volume of the first air bag  123   a  may become greater than the second air bag  123   b  when the first air bag  123   a  expands while the second air bag  123   b  remains stable, when the second air bag  123   b  contracts while the first air bag  123   a  remain stable, when the first air bag  123   a  expands more than the second air bad  123   b,  or when the first air bag  123   a  expands while the second air bag  123   b  contracts. In one example, when the amount of gas in the first air bag  123   a  increases in response to a control signal from the controller  430 , the internal pressure of the first air bag  123   a  may increase, and accordingly, the first air bag  123   a  may expand. In this case, the first spring  122   a,  which is located adjacent to the first air bag  123   a,  may extend. In another example, when the amount of gas in the second air bag  123   b  decreases in response to a control signal from the controller  430 , the internal pressure of the second air bag  123   b  may decrease, and accordingly, the second air bag  123   b  may contract. In this case, the second spring  122   b,  which is located adjacent to the second air bag  123   b , may also contract together with the second air bag  123   b.  In still another example, when the amount of gas in the first air bag  123   a  increases and the amount of gas in the second air bag  123   b  decreases in response to a control signal from the controller  430 , the internal pressure of the first air bag  123   a  may increase, and the internal pressure of the second air bag  123   b  may decrease, whereby the first air bag  123   a  may expand, and the second air bag  123   b  may contract. In this case, the first spring  122   a,  which is located adjacent to the first air bag  123   a , may extend, and the second spring  122   b,  which is located adjacent to the second air bag  123   b , may contract. 
     Referring to  FIGS.  5  and  7   , when the volume of the first air bag  123   a  becomes greater than that of the second air bag  123   b,  the vertical height of the first air bag  123   a  may become greater than that of the second air bag  123   b,  and the vertical distance between the first upper protruding portion  121   c - 1  and the first lower protruding portion  116   d - 1  may become slightly greater than the vertical distance between the second upper protruding portion  121   c - 2  and the second lower protruding portion  116   d - 2 . Accordingly, the tilting arm  116  may be tilted such that one end of the body portion  116   a,  from which the motor-coupling portion  116   c  extends, is higher than the opposite end of the body portion  116   a,  to which the bracket  116   b  is connected. Since the entirety of the brush-tilting unit  110  is tilted when the tilting arm  116  is tilted, the roll brush  111  may also be tilted such that one end thereof is higher than the opposite end thereof. For example, in the state in which the tilting arm  116  is oriented horizontally as shown in  FIG.  3   , when the volume of the first air bag  123   a  becomes greater than that of the second air bag  123   b,  the tilting arm  116  (i.e. the brush-tilting unit  110 ) may be tilted in the counterclockwise direction, as shown in  FIG.  7   . As the tilting arm  116  is tilted, the roll brush  111  and the motor  117 , which are secured to the tilting arm  116 , may also be tilted together therewith. As the roll brush  111  is tilted, the contact pressure between the surface of the roll brush  111  and the edge region of the top surface of the substrate W may increase. Accordingly, the efficiency of cleaning of the edge region of the roll brush  111  may be improved. 
     In some embodiments, the controller  430  may increase the internal pressure of the first air bag  123   a  and the internal pressure of the second air bag  123   b  such that the internal pressure of the first air bag  123   a  is greater than the internal pressure of the second air bag  123   b,  thereby making both the first air bag  123   a  and the second air bag  123   b  expand. In this case, since the volume of the first air bag  123   a  is greater than the volume of the second air bag  123   b,  the tilting arm  116  may be tilted in the counterclockwise direction. At the same time, since both the volume of the first air bag  123   a  and the volume of the second air bag  123   b  increase, the tilting arm  116  may move vertically downwards. Each of the first spring  122   a  and the second spring  122   b  may be extended. In this case, as the roll brush  111  is tilted, the contact pressure between the surface of the roll brush  111  and the edge region of the top surface of the substrate W may be increased, and the descending pressure applied to the edge region by the roll brush  111  may also be increased, thus increasing the rotational stiffness of the roll brush  111 . In another exemplary embodiment, in the case of reducing the internal pressure of the first air bag  123   a  and the internal pressure of the second air bag  123   b  so as to make the internal pressure of the first air bag  123   a  greater than the internal pressure of the second air bag  123   b,  the tilting arm  116  may be tilted in the counterclockwise direction, and may move vertically upwards at the same time. 
     As described above, the tilting arm  116  is capable of not only performing a tilting operation, but also vertical movement (adjustment), wherein the tilting operation and the vertical movement may be independently and simultaneously (i.e., at least partially overlapping in time) controlled. According to the tilting operation and/or the vertical movement of the tilting arm  116  depending on a change in the pressure of the air bag  123 , the contact pressure applied to the edge region of the substrate W by the roll brush  111  may vary, and the rotational stiffness of the roll brush  111  with respect to the substrate W may vary. 
     Referring to  FIGS.  5  and  8   , the controller  430  may control the pneumatic control module  410  such that the internal pressure of the first air bag  123   a  is less than the internal pressure of the second air bag  123   b.  Accordingly, the volume of the first air bag  123   a  may become less than that of the second air bag  123   b,  and the roll brush  111  may be tilted together with the tilting arm  116  such that one end thereof is lower than the other end. That is, in contrast to  FIG.  7   , the vertical height of the second air bag  123   b  may become greater than that of the first air bag  123   a,  and accordingly, the tilting arm  116  and the roll brush  111  may be tilted in the clockwise direction. 
     The volume of the first air bag  123   a  may become less than that of the second air bag  123   b  when only the first air bag  123   a  contracts, when only the second air bag  123   b  expands, or when the first air bag  123   a  contracts and the second air bag  123   b  expands. In each case, the first spring  122   a  may contract, and/or the second spring  122   b  may extend. 
     In some embodiments, the controller  430  may increase the internal pressure of the first air bag  123   a  and the internal pressure of the second air bag  123   b,  such that the internal pressure of the first air bag  123   a  is less than the internal pressure of the second air bag  123   b,  thereby making both the first air bag  123   a  and the second air bag  123   b  expand. In this case, since the volume of the first air bag  123   a  is less than the volume of the second air bag  123   b,  the tilting arm  116  and the roll brush  111  may be tilted in the clockwise direction. At the same time, since both the volume of the first air bag  123   a  and the volume of the second air bag  123   b  increase, the tilting arm  116  and the roll brush  111  may move vertically downwards. Each of the first spring  122   a  and the second spring  122   b  may be extended. 
     The controller  430  may independently control the internal pressure of the first air bag  123   a  and the internal pressure of the second air bag  123   b  to move the tilting arm  116  and the roll brush  111  vertically. Referring to the illustrated embodiment of  FIG.  3   , the controller  430  may increase the internal pressure of the first air bag  123   a  and the internal pressure of the second air bag  123   b,  such that the internal pressure of the first air bag  123   a  and the internal pressure of the second air bag  123   b  are the same. Accordingly, the first air bag  123   a  and the second air bag  123   b  may be expanded to the same volume, and the vertical heights thereof may increase to the same level. Accordingly, the tilting arm  116  and the roll brush  111  may move vertically downwards without being tilted. Since this vertical movement is performed more minutely than the vertical movement performed by the upper vertical adjustment unit  130 , it may be utilized to precisely control the magnitude of the descending pressure applied to the substrate W by the roll brush  111  and the rotational stiffness of the roll brush  111  with respect to the substrate W. 
       FIG.  9    is a perspective view of a substrate-cleaning apparatus according to embodiments of the inventive concept;  FIG.  10    is an enlarged perspective view of region P 2  shown in  FIG.  9   ; and  FIG.  11    is an exploded perspective view of the tilting arm and the support arm of  FIG.  10   . 
     Referring to  FIGS.  9   .  10  and  11 , an air unit  520  may include an upper bracket  522  protruding from the bottom surface of a body  521   a  of a support arm  521 , a bearing  523  secured to the upper bracket  522 , and a pivot shaft  524  penetrating the bearing  523 . Compared to the air unit  120  described above in relation to the embodiments shown in  FIGS.  2  to  8   , the air unit  520  may not include a spring. Rather, the upper bracket  522  may be positioned between a first air bag  123   a  and a second air bag  123   b,  wherein the upper bracket  522  includes a first upper bracket  522   a,  as well as a spaced apart, facing second upper bracket  522   b.    
     Here, a brush-tilting unit  510  may include a lower bracket  517  protruding from the top surface of a body portion  116   a  of a tilting arm  516 . The lower bracket  517  may be disposed between a first lower protruding portion  116   d - 1  and a second lower protruding portion  116   d - 2  of the tilting arm  516 . The lower bracket  517  may be inserted between the first upper bracket  522   a  and the second upper bracket  522   b,  and the pivot shaft  524  may be inserted into the first upper bracket  522   a,  the lower bracket  517 , and the second upper bracket  522   b,  whereby the upper bracket  522  and the lower bracket  517  may be rotatably coupled to each other. Accordingly, when there is a difference in the internal pressure between the first air bag  123   a  and the second air bag  123   b,  the tilting arm  516  and the roll brush  111  may be tilted about the pivot shaft  524 . The substrate-cleaning apparatus  20  of  FIG.  9    may perform tilting operation similar to the tilting operation described above in relation to the embodiments shown in  FIGS.  7  and  8   , except that the tilting operation is performed about the pivot shaft  524 . That is, the tilting arm  516 , the roll brush  111 , and the motor  117  may be tilted in the clockwise direction or the counterclockwise direction about the pivot shaft  524  according to expansion and/or contraction of the first air bag  123   a  and the second air bag  123   b.    
     In some embodiments, a groove  525  may be formed in the top surface of the lower protruding portion  116   d  so as to allow the lower portion of the air bag  123  to be inserted thereinto. A groove may also be formed in the bottom surface of the upper protruding portion  121   c  so as to allow the upper portion of the air bag  123  to be inserted thereinto. 
     As will be apparent to those skilled in the art upon consideration of the foregoing description of exemplary embodiments, the angle at which a roll brush is tilted may be adjusted by controlling the pneumatic pressure of respective air bag(s). Accordingly, the contact pressure between the roll brush and the edge region of a substrate may be increased, and the rotational stiffness of the roll brush may be adjusted. As a result, the efficiency of cleaning of the edge region of a substrate may be improved. In addition, a motor may be coupled to a tilting arm, to which the roll brush is secured, and the tilting arm, the roll brush, and the motor may be integrally tilted. Accordingly, it is possible to prevent an eccentric load, attributable to the tilting, from being applied to the driving shaft of the motor, thereby increasing the lifespan of the motor. In addition, the inclination of the roll brush may be automatically set through a controller, rather than being set through manual operation by a worker. Accordingly, it is possible to more precisely control the contact pressure applied to the substrate and to reduce variation in control between facilities, thereby enabling tool-to-tool matching (TTTM). 
     While the embodiments of the disclosure have been described with reference to the accompanying drawings, those skilled in the art will understood that various modifications may be made without departing from the scope of the inventive concept. Therefore, the above-described embodiments should be considered as descriptive and exemplary in nature.