Patent Publication Number: US-2021193491-A1

Title: Substrate transfer apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2019-0170205, filed on Dec. 18, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     The inventive concept relates to a substrate transfer apparatus, and more particularly, to a substrate transfer apparatus capable of transferring a warped substrate. 
     In semiconductor manufacturing, substrate transferring is the process used to move a substrate to and from various locations or machines during the manufacturing process. For example, a substrate transferring apparatus may transfer the substrate to and from various chambers for stepwise treatment of the substrate surface. 
     Semiconductor devices are then formed on the substrate in a complex process with numerous variables. The substrate transfer apparatus may include devices such as a transfer roller and a conveyor belt with small corners or rolling edges. In some cases, the substrate may be provided to the substrate transfer apparatus in a warped state, causing the substrate to be caught or snagged in the substrate transfer apparatus. 
     Therefore, there is a need in the art for a substrate transferring process that is capable of handling a warped substrate when transferring the substrate to and from different locations of the manufacturing process. 
     SUMMARY 
     The inventive concept provides a substrate transfer apparatus capable of preventing a substrate catching phenomenon, improving a substrate transfer speed, and reducing a risk of damage to a substrate. According to some embodiments, the inventive concept provides a substrate transfer apparatus capable of reducing warpage of a substrate. 
     The inventive concept provides a substrate transfer apparatus capable of reducing the abnormal transfer of a substrate by temporarily reducing warpage of the substrate when the substrate is transferred from a first transfer apparatus to a second transfer apparatus. 
     According to an aspect of the inventive concept, there is provided a substrate transfer apparatus including a first transfer apparatus configured to transfer a substrate in a first direction; a second transfer apparatus configured to receive the substrate from the first transfer apparatus, the second transfer apparatus comprising a substrate carrier configured to support the substrate and a substrate carrier driver configured to move the substrate carrier; a sensor configured to detect an abnormal transfer of the substrate from the first transfer apparatus to the second transfer apparatus and generate a detection signal corresponding to the abnormal transfer of the substrate; a swing apparatus configured to swing the substrate carrier; and a controller connected to the sensor and the swing apparatus and configured to control the swing apparatus based on the detection signal of the sensor. 
     According to another aspect of the inventive concept, there is provided a substrate transfer apparatus including a plurality of first rotation shafts; a main transfer roller coupled to each of the first rotation shafts, configured to move a substrate in a first direction, and comprising a plurality of guide portions spaced apart in a second direction perpendicular to the first direction and configured to prevent the substrate from being separated, and a transfer portion between the plurality of guide portions and configured to contact the substrate and transfer the substrate in the first direction; a camshaft disposed between the first rotation shafts; a rotation driver configured to rotate the camshaft; and an eccentric cam coupled to the camshaft and configured to raise or lower the substrate in a vertical direction, and wherein a guide distance formed by the plurality of guide portions of the main transfer roller in the second direction gradually decreases toward the first direction. 
     According to another aspect of the inventive concept, there is provided a substrate transfer apparatus for transferring a substrate in a first direction including a first lower conveyor belt including: a first lower rotation shaft; a second lower rotation shaft spaced apart from the first lower rotation shaft in the first direction and configured to rotate in the same direction as that of the first lower rotation shaft; and a first lower transfer belt configured to connect the first lower rotation shaft to the second lower rotation shaft and contacting at least a part of a lower surface of the substrate; and a first upper conveyor belt disposed above first lower conveyor belt and including a first upper rotation shaft; a second upper rotation shaft spaced apart from the first upper rotation shaft in the first direction and configured to rotate in the same direction as that of the first upper rotation shaft; and a first upper transfer belt configured to connect the first upper rotation shaft to the second upper rotation shaft and contacting at least a part of an upper surface of the substrate, and wherein the first lower conveyor belt and the first upper conveyor belt are configured to cooperate to transfer the substrate in the first direction, and the first lower transfer belt and the first upper transfer belt are spaced apart with a transfer path of the substrate therebetween. 
     According to another aspect of the inventive concept, a method of transferring a substrate is described. The method may include moving a substrate from a first portion of a substrate transferring apparatus toward a second portion of the substrate transferring apparatus; detecting an abnormal transfer from the first portion of the substrate transferring apparatus toward the second portion of the substrate transferring apparatus; generating an abnormal transfer signal based on detecting the abnormal transfer; adjusting the substrate transferring apparatus based on the abnormal transfer signal; and moving the substrate to the second portion of the substrate transferring apparatus based on adjusting the substrate transferring apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a plan view of a first substrate transfer apparatus according to an example embodiment; 
         FIG. 2  is a plan view of a second substrate transfer apparatus according to an example embodiment; 
         FIG. 3  is a plan view of a third substrate transfer apparatus according to an example embodiment; 
         FIG. 4  is a flowchart illustrating operations of a first substrate transfer method according to an example embodiment; 
         FIGS. 5 and 6  are diagrams illustrating respective operations of the first substrate transfer method according to an example embodiment; 
         FIGS. 7 and 8  are diagrams illustrating respective operations of the first substrate transfer method according to an example embodiment; 
         FIG. 9  is a plan view of a fourth substrate transfer apparatus according to an example embodiment; 
         FIG. 10  is a cross-sectional view of the fourth substrate transfer apparatus taken along the line X-X′ of  FIG. 9 ; 
         FIG. 11  is a flowchart illustrating operations of a second substrate transfer method according to an example embodiment; 
         FIGS. 12 and 13  are diagrams illustrating respective operations of the second substrate transfer method; 
         FIG. 14  is a plan view of a fifth substrate transfer apparatus according to an example embodiment; 
         FIG. 15  is a cross-sectional view of the fifth substrate transfer apparatus according to an example embodiment; 
         FIG. 16  is a cross-sectional view of a sixth substrate transfer apparatus according to an example embodiment; 
         FIG. 17  is a cross-sectional view of a seventh substrate transfer apparatus according to an example embodiment; 
         FIG. 18  is a flowchart showing operations of a third substrate transfer method according to an example embodiment; and 
         FIGS. 19 to 23  are diagrams showing respective operations of the third substrate transfer method. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present disclosure relates to semiconductor manufacturing. More specifically, embodiments of the present disclosure provide a substrate transfer apparatus capable of preventing a substrate catching phenomenon. A substrate transfer apparatus according to the present disclosure may include a sensor sensing abnormal transfer of the substrate and a swing or other component used to move the transfer apparatus when an abnormal transfer signal is provided by the sensor. Some embodiments of transfer apparatus may also include a mechanism that contacts the upper and lower portions of the substrate to mitigate warping when a warped substrate is transferred. 
     For example, the substrate transfer apparatus of the present disclosure may include a roller having a narrow guide distance in the transfer direction of the substrate. The substrate may be automatically aligned while being transferred. Additionally or alternatively, the substrate transfer device may include a cam device. The cam may raise the substrate when the substrate is caught in the substrate transfer apparatus. In some embodiments, a conveyor belt in front of the transfer roller may be used. Additionally or alternatively, the conveyor belt may be inclined upward. As a result, the conveyor belt may transfer the substrate to the transfer roller when the substrate is warped. 
     Accordingly, embodiments of the substrate transfer apparatus may include a first transfer apparatus, a second transfer apparatus, a substrate carrier driver, a sensor, a swing apparatus, and a controller. The first transfer apparatus is configured to transfer a substrate in a first direction. The second transfer apparatus is configured to receive the substrate from the first transfer apparatus and transfer the substrate and comprising a substrate carrier on which the substrate transferred from the first transfer apparatus is seated. The substrate carrier driver is configured to move the substrate carrier. The sensor is configured to detect an abnormal transfer of the substrate from the first transfer apparatus to the second transfer apparatus and generate a detection signal corresponding to the abnormal transfer of the substrate. The swing apparatus is configured to swing the substrate carrier. The controller is connected to the sensor and the swing apparatus and configured to control the swing apparatus based on the detection signal of the sensor. 
     Hereinafter, embodiments of the inventive concept will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a plan view of a first substrate transfer apparatus  1   a  according to an example embodiment. The first substrate transfer apparatus  1   a  may be an apparatus for transferring a substrate S in a first direction X. The first substrate transfer apparatus  1   a  may transfer the substrate S in the first direction X. For example, the first substrate transfer apparatus  1   a  may transfer the substrate S for a process of processing the substrate S, such as a wire bonding process, a semiconductor chip attaching process, a molding process, a solder ball attaching process, etc. Additionally or alternatively, the first substrate transfer apparatus  1   a  may transfer the substrate S for carrying in or out the substrate S into or from a chamber. The substrate S transferred by the first substrate transfer apparatus  1   a  may include a wafer, a printed circuit board, or the like. 
     Referring to  FIG. 1 , the first substrate transfer apparatus  1   a  may include a first transfer apparatus  10 , a second transfer apparatus  20 , a sensor  300 , a swing apparatus  350 , and a controller  400 . 
     In an example embodiment, the first transfer apparatus  10  may include a supporter  110 , a first rotation shaft  120 , a main transfer roller  130 , a second rotation shaft  140 , an auxiliary transfer roller  150 , a first rotation driver  160 , and a second rotation driver  170 . 
     The first transfer apparatus  10  may transfer the substrate S to the second transfer apparatus  20 . The first transfer apparatus  10  may provide a plurality of paths through which the substrate S is transferred. For example, as shown in  FIG. 1 , the first transfer apparatus  10  may provide four transfer paths. However, the inventive concept is not limited thereto. The number of transfer paths of the substrate S provided by the first transfer apparatus  10  may be one or more. 
     The supporter  110  may be configured to support the first rotation shaft  120  and the second rotation shaft  140 . In an example embodiment, two supporters  110  may be provided, and the two supporters  110  may be spaced apart from each other in a second direction Y perpendicular to a first direction X, which is a direction in which the substrate S is transferred. For example, the supporter  110  may have an opening (not shown), and the first rotation shaft  120  and the second rotation shaft  140  may be in the opening. 
     The first rotation shaft  120  may extend in the second direction Y between the supporters  110  and may rotate in a first rotation direction. The first rotation direction may be a rotation direction for transferring the substrate S in the first direction X. The first rotation shaft  120  may be rotated by the power of the first rotation driver  160 . 
     The main transfer roller  130  may be a roller coupled to the first rotation shaft  120  and configured to transfer the substrate S in the first direction X. In an example embodiment, the main transfer roller  130  may include a guide portion  135  and a transfer portion  137 . 
     In an example embodiment, the first transfer apparatus  10  may include a plurality of main transfer rollers  130 . Each of the plurality of main transfer rollers  130  may include a pair of guide portions  135 . The guide portions  135  may be spaced apart by a guide distance d in the second direction Y perpendicular to the first direction X and the transfer portion  137 . The transfer portion  137  may extend between the pair of guide portions  135  and configured to contact the substrate S and transfer the substrate S in the first direction X. 
     The guide distance d may be defined as a distance formed by the guide portion  135  in the second direction Y. Additionally or alternatively, the guide distance d may be substantially the same as the distance of the transfer portion  137  of the main transfer roller  130  in the second direction Y. The guide distance d formed by the main transfer roller  130  may gradually decrease in the first direction X. As a result, the substrate S may be aligned without being separated while being transferred in the first direction X. The guide distance d of the main transfer roller  130  will be described in more detail later. 
     The guide portion  135  may be a portion of the main transfer roller  130  configured to surround a side portion of the substrate S and prevent the substrate S from being separated. The transfer portion  137  may be a portion of the main transfer roller  130  between the guide portions  135  and directly in contact with the substrate S. When the transfer portion  137  of the main transfer roller  130  is viewed in a planar view (X-Y plane), the transfer portion  137  may have an hourglass shape with a cross-sectional area tapered toward the center, but the present disclosure is not limited to the hourglass shape and may be a different shape. 
     The second rotation shaft  140  may be between the supporters  110  and may be configured to rotate in the first rotation direction. Additionally or alternatively, the second rotation shaft  140  may be configured to rotate in the same direction as the first rotation direction, wherein the first rotation direction is the rotation direction of the first rotation shaft  120 , between the first rotation shafts  120 . The second rotation shaft  140  may be rotated by the power of the second rotation driver  170 . 
     The auxiliary transfer roller  150  may be a roller coupled to the second rotation shaft  140  and configured to transfer the substrate S in the first direction X. In an example embodiment, the auxiliary transfer roller  150  may have a cylindrical shape. 
     The first rotation driver  160  may include a driving apparatus configured to rotate the first rotation shaft  120  in the first rotation direction. For example, the first rotation driver  160  may include a combination of a motor and gears. Additionally or alternatively, the second rotation driver  170  may include a driving apparatus configured to rotate the second rotation shaft  140  in the first rotation direction. For example, the second rotation driver  170  may include a combination of a motor and gears. 
     In an example embodiment, the first rotation driver  160  and the second rotation driver  170  may include different motors. However, the inventive concept is not limited thereto, and the first rotation driver  160  and the second rotation driver  170  may be interconnected by a plurality of gears or belts and may include one or more motors. 
     The second transfer apparatus  20  may receive the substrate S from the first transfer apparatus  10  and transfer the substrate S. The second transfer apparatus  20  may transfer the substrate S in a direction different from the first direction X (e.g., any one of the second direction Y and a vertical direction Z). For example, as illustrated in  FIG. 1 , the second transfer apparatus  20  may transfer the substrate S received from the first transfer apparatus  10  in the second direction Y. However, the inventive concept is not limited thereto, and the second transfer apparatus  20  may transfer the substrate S in the first direction X and the vertical direction Z. 
     In an example embodiment, the second transfer apparatus  20  may include a guide rail  210 , a substrate carrier  220 , and a substrate carrier driver  230 . For example, the second transfer apparatus  20  may include a transfer shuttle. 
     The guide rail  210  may include a rail providing a path through which the substrate carrier  220  may move. For example, The guide rail  210  may extend in the second direction Y when the second transfer apparatus  20  is configured to transfer the substrate S in the second direction Y. 
     The substrate carrier  220  may be an apparatus on which the substrate S transferred from the first transfer apparatus  10  is seated. The substrate carrier  220  may be slide—coupled to the guide rail  210  and may slide in a direction in which the guide rail  210  extends. For example, when the guide rail  210  extends in the second direction Y, the substrate carrier  220  may slide in the second direction Y. 
     In an example embodiment, the substrate carrier  220  may include a support plate  223  and a guide plate  227 . The support plate  223  of the substrate carrier  220  may include a plate on which the substrate S transferred from the first transfer apparatus  10  is seated. 
     Additionally or alternatively, the guide plate  227  may include a plate configured to protrude upward from two opposite edges of the support plate  223  to support the side portion of the substrate S. The guide plate  227  may have a guide groove (not shown) extending in the first direction X to guide the substrate S. 
     The substrate carrier driver  230  may include power apparatuses configured to move the substrate carrier  220  on the guide rail  210 . For example, the substrate carrier driver  230  may be a combination of a motor and a gear. 
     The sensor  300  may be configured to detect an abnormal transfer of the substrate S. Additionally or alternatively, the sensor  300  may be configured to detect whether the substrate S is normally transferred from the first transfer apparatus  10  to the second transfer apparatus  20 . For example, the sensor  300  may detect the abnormal transfer of the substrate S when the substrate S collides with a part of the substrate carrier  220  of the second transfer apparatus  20  and is not transferred to the second transfer apparatus  20 . For example, the sensor  300  may include a camera, a pressure sensor, or a proximity sensor that emits an output signal (e.g., an electromagnetic or ultrasonic signal) and detects reflected portions of the output signal. 
     Additionally or alternatively, the sensor  300  may be configured to generate a detection signal of the abnormal transfer and transmit the generated detection signal to the controller  400  when the abnormal transfer of the substrate S is detected. 
     The sensor  300  may generate different abnormal detection signals based on various kinds of abnormal transfer of the substrate S. In an example embodiment, the sensor  300  may generate different detection signals according to a catching position of the substrate S. When the substrate S is caught in the side portion of the substrate carrier  220  of the second transfer apparatus  20 , the sensor  300  may generate a first abnormal catching signal and transmit the first abnormal catching signal to the controller  400 . Additionally or alternatively, when the substrate S is caught in the lower portion of the substrate carrier  220  of the second transfer apparatus  20 , the sensor  300  may generate a second abnormal catching signal different from the first abnormal catching signal and transmit the second abnormal catching signal to the controller  400 . 
     In an example embodiment, the sensor  300  may generate different detection signals depending on the collision intensity of the substrate S and the substrate carrier  220 . For example, when the substrate S collides with a part of the substrate carrier  220  at a first intensity in a state where the substrate S is not mounted on the substrate carrier  220 , the sensor  300  may generate a first abnormal collision signal. Then, the sensor  300  may transmit the first abnormal collision signal to the controller  400 . Additionally or alternatively, when the substrate S collides with a part of the substrate carrier  220  at a second intensity different from the first intensity in the state where the substrate S is not mounted on the substrate carrier  220 , the sensor  300  may generate a second abnormal collision signal and transmit the second abnormal collision signal to the controller  400 . 
     In an example embodiment, the sensor  300  may be between the first transfer apparatus  10  and the second transfer apparatus  20 . However, the position of the sensor  300  is not limited to the above and may vary. For example, the sensor  300  may be in at least one of the first transfer apparatus  10  and the second transfer apparatus  20 . 
     In an example embodiment, the sensor  300  may include an optical sensor. For example, the sensor  300  may include a transmitter configured to emit light and a receiver configured to receive the light emitted from the transmitter. The sensor  300  may detect the abnormal transfer of the substrate S based on whether light is detected, the intensity of the light, and the like. Additionally or alternatively, the sensor  300  may include a pressure sensor. Details of the pressure sensor will be described in more detail with reference to  FIG. 3 . 
     The swing apparatus  350  may be configured to swing the substrate carrier  220 . Additionally or alternatively, when the sensor  300  detects the abnormal transfer of the substrate S, the swing apparatus  350  may apply a vibration to the substrate carrier  220 . The vibration may be used to swing the substrate carrier  220 . For example, the swing apparatus  350  may include a vibrator apparatus configured to apply vibration to the substrate carrier  220  in the horizontal direction and/or in the vertical direction. 
     In an example embodiment, the swing apparatus  350  may adjust the period of vibration applied to the substrate carrier  220 , the amplitude of vibration, or the time for applying vibration, etc. For example, based on various abnormal detection signals generated by the sensor  300 , the swing apparatus  350  may adjust the period of vibration applied to the substrate carrier  220 , amplitude, time for applying vibration, etc. 
     In an example embodiment, the swing apparatus  350  may include at least one of a first swing apparatus  350   a  and a second swing apparatus  350   b.  For example, the swing apparatus  350  may include both the first swing apparatus  350   a  and the second swing apparatus  350   b.  The first swing apparatus  350   a  may include an apparatus configured to swing the substrate carrier  220  in the horizontal direction. The second swing apparatus  350   b  may include an apparatus configured to swing the substrate carrier  220  in the vertical direction. 
     In an example embodiment, when the substrate S is caught in the side portion of the substrate carrier  220 , the first swing apparatus  350   a  may swing the substrate carrier  220  in the horizontal direction. As a result, the substrate S may be stably mounted on the support plate  223  of the substrate carrier  220 . Additionally or alternatively, when the substrate S is caught in the lower portion of the substrate carrier  220 , the second swing apparatus  350   b  may swing the substrate carrier  220  in the vertical direction. As a result, the substrate S may be stably mounted on the support plate  223  of the substrate carrier  220 . 
     The controller  400  may be configured to generally control the transfer of the substrate S using the first transfer apparatus  10  and the second transfer apparatus  20 . In an example embodiment, the controller  400  may be connected to the first rotation driver  160 , the second rotation driver  170 , the substrate carrier driver  230 , the sensor  300 , and the swing apparatus  350 . 
     In an example embodiment, the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  based on the detection signal of the abnormal transfer of the substrate S transmitted by the sensor  300 . For example, when the sensor  300  transmits different detection signals to the controller  400 , corresponding to various kinds of the abnormal transfer of the substrate S, the controller  400  may control the swing apparatus  350  to move the substrate carrier  220  differently based on the detection signals. 
     In an example embodiment, the controller  400  may control the swing apparatus  350  to adjust at least one of the vibration direction and the vibration intensity of the substrate carrier  220  based on the above-described detection signals. Additionally or alternatively, the controller  400  may control the period of vibration applied by the swing apparatus  350  to the substrate carrier  220 , the time for applying vibration, and the like. 
     In an example embodiment, when the controller  400  receives the detection signal of the abnormal transfer of the substrate S from the sensor  300 , the controller  400  may gradually increase the intensity of vibration applied by the swing apparatus  350  to the substrate carrier  220 . 
     In an example embodiment, the controller  400  may be implemented in hardware, firmware, software, or any combination thereof. For example, the controller  400  may include a computing apparatus, such as a workstation computer, a desktop computer, a laptop computer, a tablet computer, or the like. The controller  400  may include a simple controller, a complex processor such as a microprocessor, a CPU, a GPU, or the like, a processor configured by software, dedicated hardware, or firmware. The controller  400  may be implemented by, for example, a general-purpose computer or application-specific hardware such as a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or the like. 
     In an example embodiment, the operation of the controller  400  may be implemented as instructions stored on a machine-readable medium that may be read and executed by one or more processors. Here, the machine-readable medium may include any mechanism for storing and/or transmitting information that may be readable by a machine (e.g., a computing apparatus). 
     The first substrate transfer apparatus  1   a , according to an example embodiment, may include the sensor  300  that detects the abnormal transfer of the substrate S (e.g., catching of the substrate S, etc.) and the swing apparatus  350  that swings the substrate carrier  220  when the abnormal transfer of the substrate S is detected. As a result, abnormal transfer of the substrate S is prevented, substrate transfer speed is increased, and the risk of damage to the substrate S is reduced. 
       FIG. 2  is a plan view of a second substrate transfer apparatus  1   b  according to an example embodiment. Hereinafter, redundant descriptions of the first substrate transfer apparatus  1   a  of  FIG. 1  and the second substrate transfer apparatus  1   b  will be omitted, and differences therebetween will be mainly described. 
     Referring to  FIG. 2 , the second substrate transfer apparatus  1   b  may include a first sensor  310   a  and a second sensor  310   b.  The first sensor  310   a  may include a sensor configured to detect whether the substrate S is normally carried in into the substrate carrier  220 , and the second sensor  310   b  may include a sensor configured to detect whether the substrate S is normally carried out from the substrate carrier  220 . 
     In an example embodiment, the first sensor  310   a  and the second sensor  310   b  may be on the support plate  223  of the substrate carrier  220 . For example, the first sensor  310   a  may be mounted on a part of the support plate  223  adjacent to a part that the substrate S is carried in, and the second sensor  310   b  may be mounted on a part of the support plate  223  adjacent to a part that the substrate S is carried out. However, the positions of the first sensor  310   a  and the second sensor  310   b  are not limited to the above. 
     In an example embodiment, the first sensor  310   a  and the second sensor  310   b  may detect whether the substrate S has passed through the upper portions of the first sensor  310   a  and the second sensor  310   b.  For example, the first sensor  310   a  and the second sensor  310   b  may include an optical sensor that emits light and detects whether the substrate S has passed through the upper portions of the first sensor  310   a  and the second sensor  310   b  by using the light. 
     Additionally or alternatively, the first sensor  310   a  and the second sensor  310   b  may include a pressure sensor that receives pressure applied by the substrate S and detects whether the substrate S has passed through the upper portions of the first sensor  310   a  and the second sensor  310   b  by using the pressure applied by the substrate S. 
     In an example embodiment, when the substrate S passes through the upper portion of the first sensor  310   a,  the first sensor  310   a  may generate a normal carry-in signal and transmit the normal carry-in signal to the controller  400 . In this case, the controller  400  may not operate the swing apparatus  350 . Additionally or alternatively, when the substrate S does not pass through the upper portion of the first sensor  310   a  and stays on the upper portion of the first sensor  310   a  for more than a predetermined time, the first sensor  310   a  may generate an abnormal carry-in signal and transmit the abnormal carry-in signal to the controller  400 . In this case, the controller  400  may operate the swing apparatus  350  to swing the substrate carrier  220 . 
     In an example embodiment, when the substrate S passes through the upper portion of the second sensor  310   b,  the second sensor  310   b  may generate a normal carry-out signal and transmit the normal carry-out signal to the controller  400 . In this case, the controller  400  may not operate the swing apparatus  350 . Additionally or alternatively, when the substrate S does not pass through the upper portion of the second sensor  310   b  and stays on the upper portion of the second sensor  310   b  for more than a predetermined time, the second sensor  310   b  may generate an abnormal carry-in signal and transmit the abnormal carry-in signal to the controller  400 . In this case, the controller  400  may operate the swing apparatus  350  to swing the substrate carrier  220 . 
       FIG. 3  is a plan view of a third substrate transfer apparatus  1   c  according to an example embodiment. Hereinafter, redundant descriptions of the first substrate transfer apparatus  1   a  of  FIG. 1  and the third substrate transfer apparatus  1   c  will be omitted, and differences therebetween will be mainly described. 
     Referring to  FIG. 3 , the third substrate transfer apparatus  1   c  may include a third sensor  320 . In an example embodiment, the third sensor  320  may include a sensor configured to detect a collision between the substrate S and the substrate carrier  220 . 
     In an example embodiment, the third sensor  320  may include a pressure sensor. The third sensor  320  may detect a collision position, collision intensity, and the like of the substrate S and the substrate carrier  220  and generate abnormal collision signals based on the collision position and the collision intensity. The controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  differently based on different abnormal collision signals. However, the inventive concept is not limited thereto, and the third sensor  320  may detect the collision intensity, and a separate camera may detect the collision position. 
     In an example embodiment, when the third sensor  320  generates a first abnormal collision signal including a first collision position and a first collision intensity of the substrate S and the substrate carrier  220  and transmits the first abnormal collision signal to the controller  400 , the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  at a first intensity and in a first direction. When the third sensor  320  generates a second abnormal collision signal including a second collision position and a second collision intensity respectively different from the first collision position and the first collision intensity of the substrate S and the substrate carrier  220  and transmits the second abnormal collision signal to the controller  400 , the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  at a second intensity and in a second direction. 
       FIG. 4  is a flowchart illustrating operations of a first substrate transfer method S 10  according to an example embodiment.  FIGS. 5 and 6  are diagrams illustrating respective operations of the first substrate transfer method S 10 .  FIGS. 7 and 8  are diagrams illustrating the respective operations of the first substrate transfer method S 10 . 
     Additionally or alternatively, the first substrate transfer method S 10 , according to an example embodiment, may include a method of transferring the substrate S in the first direction X using the substrate transfer apparatus  1   a  described with reference to  FIG. 1 . 
     Referring to  FIG. 4 , the first substrate transfer method S 10  may include operation S 110  of detecting an abnormal transfer of the substrate S, operation S 120  of determining a type of the abnormal transfer of the substrate S, and operation S 130  of swinging the substrate carrier  220  based on the type of the abnormal transfer of the substrate S. 
     Referring to  FIGS. 4, 5, and 7  together, the first substrate transfer method S 10  may include operation S 110  of detecting an abnormal transfer of the substrate S. In operation S 110 , the sensor  300  may detect the abnormal transfer of the substrate S, generate a detection signal of the abnormal transfer of the substrate S and transmit the generated detection signal to the controller  400 . 
     In operation S 110 , the sensor  300  may generate different detection signals according to the catching position of the substrate S and transmit the generated detection signals to the controller  400 . In an exemplary embodiment, as shown in  FIG. 4 , when the substrate S is caught in the side portion of the substrate carrier  220 , the sensor  300  may generate a first abnormal catching signal and transmit the first abnormal catching signal to the controller  400 . 
     Additionally or alternatively, as shown in  FIG. 7 , when the substrate S is caught in the lower portion of the substrate carrier  220 , the sensor  300  may generate a second abnormal catching signal different from the first abnormal catching signal and transmit the second abnormal catching signal to the controller  400 . 
     Additionally or alternatively, in operation S 110 , the sensor  300  may generate different detection signals according to the collision intensity of the substrate S and the substrate carrier  220 . The sensor  300  may transmit the detection signals to the controller  400 . For example, when the substrate S collides with a part of the substrate carrier  220  at a first intensity in a state where the substrate S is not mounted on the substrate carrier  220 , the sensor  300  may generate a first abnormal collision signal and transmit the first abnormal collision signal to the controller  400 . Additionally or alternatively, when the substrate S collides with a part of the substrate carrier  220  at a second intensity different from the first intensity in the state where the substrate S is not mounted on the substrate carrier  220 , the sensor  300  may generate a second abnormal collision signal and transmit the second abnormal collision signal to the controller  400 . 
     The first substrate transfer method S 10  may include operation S 130  of swinging the substrate carrier  220  based on the type of the abnormal transfer of the substrate S. In operation S 130 , when the abnormal transfer of the substrate S is detected, the controller  400  may determine the type of the abnormal transfer of the substrate S. 
     In an example embodiment, when the controller  400  receives at least one of the above-described abnormal catching signals and abnormal collision signals from the sensor  300 , the controller  400  may determine the catching position of the substrate S and the collision intensity of the substrate S and the substrate carrier  220 . Additionally or alternatively, the controller  400  may calculate the intensity of vibration to be applied to the substrate carrier  220  and the direction of vibration based on the catching position of the substrate S and the collision intensity of the substrate S and the substrate carrier  220 . 
     Referring to  FIGS. 4, 6, and 8 , the first substrate transfer method S 10  may include operation S 150 , wherein operation S 150  is the swinging the substrate carrier  220  based on the type of the abnormal transfer of the substrate S. In operation S 150 , the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  differently based on types of abnormal transfer of the substrate S received from the sensor  300 . 
     As shown in  FIG. 6 , when the controller  400  receives the above-described first abnormal catching signal from the sensor  300 , the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  in the horizontal direction. In other words, the controller  400  may operate the first swing apparatus  350   a  to swing the substrate carrier  220  in the horizontal direction. 
     Additionally or alternatively, as shown in  FIG. 8 , when the controller  400  receives the above-described second abnormal catching signal from the sensor  300 , the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  in the vertical direction. In other words, the controller  400  may operate the second swing apparatus  350   b  to swing the substrate carrier  220  in the vertical direction. 
     In an example embodiment, the controller  400  may control the swing apparatus  350  to swing the substrate carrier  220  at different intensities based on abnormal collision signals received from the sensor  300 . For example, the controller  400  may control the magnitude of the amplitude of vibration applied to the substrate carrier  220  based on the abnormal collision signals received from the sensor  300 . 
     The first substrate transfer method S 10  according to an example embodiment may determine the type of the abnormal transfer of the substrate S and control the swing apparatus  350  to swing the substrate carrier  220  based on the type of the abnormal transfer, thereby preventing the abnormal transfer of the substrate S, improving substrate transfer speed, and preventing physical damage of the substrate S. 
       FIG. 9  is a plan view of a fourth substrate transfer apparatus  2  according to an example embodiment.  FIG. 10  is a cross-sectional view of the fourth substrate transfer apparatus  2  taken along the line X-X′ of  FIG. 9 . 
     Referring to  FIGS. 9 and 10 , the fourth substrate transfer apparatus  2  may include the supporter  110 , the first rotation shaft  120 , the main transfer roller  130 , the second rotation shaft  140 , the auxiliary transfer roller  150 , the first rotation driver  160 , the second rotation driver  170 , a camshaft  180 , a third rotation driver  190 , and an eccentric cam  195 . Additionally or alternatively, the fourth substrate transfer apparatus  2  may further include the sensor  300 , the controller  400 , a camera  425 , and a guide distance adjuster  475 . 
     Descriptions of the supporter  110 , the first rotation shaft  120 , the main transfer roller  130 , the second rotation shaft  140 , the auxiliary transfer roller  150 , the first rotation driver  160 , and the second rotation driver  170  of the fourth substrate transfer apparatus  2  according to an example embodiment are redundant with those described with reference to  FIG. 1 . Therefore, detailed descriptions thereof will be omitted. 
     In an example embodiment, the camshaft  180  may be between the supporters  110  and configured to rotate. The camshaft  180  may be disposed between the first rotation shafts  120  and may be rotated by the power of the third rotation driver  190 . 
     The third rotation driver  190  may include a driving apparatus configured to rotate the camshaft  180 . The third rotation driver  190  may include a combination of a motor and gears. For example, the third rotation driver  190  may include a servo motor. 
     The eccentric cam  195  may be coupled to the camshaft  180  and configured to move the substrate S in the vertical direction Z. The eccentric cam  195  may include a mechanical apparatus for switching the rotational movement of the camshaft  180  into a reciprocating movement in the vertical direction Z of the substrate S. 
     Additionally or alternatively, the eccentric cam  195  may be configured to switch between a first cam position and a second cam position. When the substrate S is normally transferred in the first direction X, the eccentric cam  195  may be in the first cam position. When the eccentric cam  195  is in the first cam position, the substrate S may not be in contact with the eccentric cam  195  and may be in contact with the transfer roller  130 . As a result, the substrate S may be transferred in the first direction X. 
     Additionally or alternatively, when the substrate S is not normally transferred in the first direction X (e.g., when the substrate S is caught in at least one of the main transfer roller  130  and the auxiliary transfer roller  150 ), the eccentric cam  195  may be in the second cam position different from the first cam position. When the eccentric cam  195  is in the second cam position, the substrate S may be in contact with the eccentric cam  195  and may be raised in the vertical direction Z by the eccentric cam  195 . 
     Additionally or alternatively, the second cam position may be a position where the eccentric cam  195  rotates about 180 degrees from the first cam position. During a process of changing the eccentric cam  195  from the first cam position to the second cam position, the substrate S may be in contact with a part of the eccentric cam  195  and raised in the vertical direction Z. During a process of raising the substrate S in the vertical direction Z, the catching phenomenon of the substrate S may be eliminated. 
     Additionally or alternatively, during a process of changing the eccentric cam  195  from the second cam position to the first cam position, the substrate S may be in contact with the transfer roller  130  and spaced apart from the eccentric cam  195 . As a result, the substrate S may be normally transferred in the first direction X. 
     In an example embodiment, the distance formed by the guide portion  135  of the main transfer roller  130  in the second direction Y may be defined as the guide distance d. Additionally or alternatively, the guide distance d may be substantially the same as the length of the transfer portion  137  of the main transfer roller  130  in the second direction Y. The guide distance d formed by the guide portion  135  of the main transfer roller  130  may gradually decrease in the first direction X. Hereinafter, the guide distance d formed by the main transfer roller  130  will be described in more detail. 
     In an example embodiment, the transfer roller  130  first in contact with the substrate S among the plurality of transfer rollers  130  may be defined as the first transfer roller  130   a.  Additionally or alternatively, the transfer roller  130  in final contact with the substrate S among the plurality of transfer rollers  130  may be defined as a second transfer roller  130   b.    
     The first transfer roller  130   a  may include first guide portions  135   a  and a first transfer portion  137   a  between the first guide portions  135   a,  and the second transfer roller  130   b  may include second guide portions  135   b  and a second transfer portion  137   b  between the second guide portions  135   b.    
     In an example embodiment, a first guide distance d 1  formed by the first guide portion  135   a  of the first transfer roller  130   a  may be about 1.20 times to about 1.50 times the length of the substrate S in the second direction Y. For example, when the length of the substrate S in the second direction Y is about 77.5 millimeters (mm), the first guide distance d 1  may be between about 93 mm and about 116 mm. Additionally or alternatively, when the length of the substrate S in the second direction Y is about 77.5 millimeters (mm), the first guide distance d 1  may be about 98 mm. 
     Also, a second guide distance d 2  formed by the second guide portion  135   b  of the second transfer roller  130   b  may be about 1.01 to about 1.10 times the length of the substrate S in the second direction Y. For example, when the length of the substrate S in the second direction Y is about 77.5 mm, the second guide distance d 2  may be about 78.3 mm to about 85.3 mm. Additionally or alternatively, when the length of the substrate S in the second direction Y is about 77.5 millimeters (mm), the second guide distance d 2  may be about 80.0 mm. 
     The guide distance d formed by the guide portion  135  of the main transfer roller  130  may decrease in the first direction X, such that the substrate S may be automatically aligned in the first direction X. 
     In an example embodiment, the guide distance adjuster  475  may be configured to adjust the guide distance d of the guide portion  135  of the main transfer roller  130 . For example, the guide distance adjuster  475  may be connected to the plurality of guide portions  135  of the main transfer roller  130  and may adjust the guide distance d. For example, the guide distance adjuster  475  may include an actuator for driving the guide portion  135  in the second direction Y. 
     In an example embodiment, the sensor  300  may be configured to generate a detection signal of abnormal transfer of the substrate S and transmit the detection signal to the controller  400 . For example, when the substrate S is caught in at least one of the main transfer roller  130  and the auxiliary transfer roller  150  and is not transferred in the first direction X, the sensor  300  may generate the detection signal of abnormal transfer of the substrate S and transmit the detection signal to the controller  400 . The technical idea of the sensor  300  may be substantially the same as that described with reference to  FIG. 1 . Therefore, a detailed description thereof is omitted. 
     In an example embodiment, the camera  425  may be configured to observe the transfer of the substrate S in the first direction X. Further, the camera  425  may provide an image of the transfer of the substrate S in the first direction X to a display in real-time. 
     In an example embodiment, the controller  400  may be configured to generally control the transfer of the substrate S using the fourth substrate transfer apparatus  2 . The controller  400  may be connected to the first rotation driver  160 , the second rotation driver  170 , the third rotation driver  190 , the sensor  300 , the camera  425 , and the guide distance adjuster  475 . 
     In an example embodiment, when the abnormal transfer of the substrate S is detected from the sensor  300  and the camera  425 , the controller  400  may rotate the eccentric cam  195  by driving the third rotation driver  190  so as to raise the substrate S in the vertical direction. Additionally or alternatively, the controller  400  may control the guide distance adjuster  475  to adjust the guide distance d formed by the guide portion  135 , based on the size of the substrate S and the degree of warpage of the substrate S. 
     The fourth substrate transfer apparatus  2 , according to an example embodiment, may include the eccentric cam  195  configured to raise the substrate S in the vertical direction, thereby preventing a catching phenomenon of the substrate S, improving the substrate transfer speed, and preventing damage to the substrate S. 
       FIG. 11  is a flowchart illustrating operations of a second substrate transfer method S 20  according to an example embodiment.  FIGS. 12 and 13  are diagrams illustrating respective operations of the second substrate transfer method S 20 . Additionally or alternatively, the second substrate transfer method S 20  may include a method of transferring the substrate S in the first direction X through the fourth substrate transfer apparatus  2  described above. 
     The second substrate transfer method S 20  may include operation S 210  of detecting an abnormal transfer of the substrate S, operation S 230  of raising the substrate S through the eccentric cam  195 , and operation S 250  of lowering the substrate S through the eccentric cam  195 . 
     Referring to  FIGS. 11 and 12 , in operation S 210 , the abnormal transfer of the substrate S may be detected through the sensor  300  and the camera  425 . In an example embodiment, when the substrate S is caught in at least one of the main transfer roller  130  and the auxiliary transfer roller  150  and is not transferred in the first direction, the sensor  300  may detect a detection signal of the abnormal transfer of the substrate S and transmit the detection signal to the controller  400 . 
     Additionally or alternatively, when the substrate S is caught in at least one of the main transfer roller  130  and the auxiliary transfer roller  150  and is not transferred in the first direction, a process operator may detect the abnormal transfer of the substrate S through the image transmitted by the camera  425  to the display. 
     Referring to  FIGS. 11 and 13  together, in operation S 230 , the substrate S may be raised in the vertical direction Z through the eccentric cam  195 . In an example embodiment, the controller  400  may drive the third rotation driver  190  to change the eccentric cam  195  from a first cam position to a second cam so as to raise the substrate S in the vertical direction Z. During a process of changing the eccentric cam  195  from the first cam position to the second cam position, the substrate S may be in contact with a part of the eccentric cam  195  and may be raised in the vertical direction Z. During a process of raising the substrate S in the vertical direction Z, a catching phenomenon of the substrate S may be eliminated. 
     Operation S 230  may be performed according to instructions of the controller  400  receiving an abnormal transfer signal of the substrate S of the sensor  300 . However, the inventive concept is not limited thereto, and operation S 230  may be performed according to instructions of the process operator that detects an abnormal transfer state of the substrate S through the image provided by the camera  425 . 
     In an example embodiment, in operation S 250 , the substrate S may be lowered in the vertical direction Z through the eccentric cam  195 . In an example embodiment, the controller  400  may drive the third rotation driver  190  to change the eccentric cam  195  from the second cam position to the first cam position so as to lower the substrate S in the vertical direction Z. During a process of changing the eccentric cam  195  from the second cam position to the first cam position, the substrate S may be in contact with a part of the transfer roller  130  and transferred in the first direction X. 
     The second substrate transfer method S 20 , according to an example embodiment, may detect the abnormal transfer of the substrate S. When the abnormal transfer of the substrate S is detected, the second substrate transfer method S 20  may raise the substrate S in the vertical direction using the eccentric cam  195 , thereby preventing the catching phenomenon of the substrate S. As a result, the second substrate transfer method S 20  may increase the substrate transfer speed and prevent damage to the substrate S. 
     Thus, according to embodiments of the inventive concept, a method of transferring a substrate may include moving a substrate from a first portion of a substrate transferring apparatus (e.g., a first transfer apparatus  10  or a first main transfer roller  130 ) toward a second portion of the substrate transferring apparatus (e.g., a second transfer apparatus  20  or a second main transfer roller  130 ); detecting an abnormal transfer from the first portion of the substrate transferring apparatus toward the second portion of the substrate transferring apparatus; generating an abnormal transfer signal based on detecting the abnormal transfer; adjusting the substrate transferring apparatus based on the abnormal transfer signal; and moving the substrate to the second portion of the substrate transferring apparatus based on adjusting the substrate transferring apparatus. 
     In some examples, the abnormal transfer comprises a collision between the substrate and the second portion of the substrate transferring apparatus. According to one embodiment, adjusting the substrate transferring apparatus comprises moving second portion of the substrate transferring apparatus to receive the substrate (e.g., moving or vibrating the second transfer apparatus  20 ). According to another embodiment, adjusting the substrate transferring apparatus comprises rotating an eccentric cam (e.g., eccentric cam  195 ) of the substrate transferring apparatus to change a vertical position of a portion of the substrate such that the second portion of the substrate transferring apparatus (e.g., a second main transfer roller  130 ) can receive the substrate (e.g., from a first main transfer roller  130 ). 
       FIG. 14  is a plan view of a fifth substrate transfer apparatus  3  according to an example embodiment, and  FIG. 15  is a cross-sectional view of the fifth substrate transfer apparatus  3 , according to an example embodiment. Referring to  FIGS. 14 and 15  together, the fifth substrate transfer apparatus  3  may include an apparatus configured to transfer the substrate S in the first direction X. The fifth substrate transfer apparatus  3  may include a third transfer apparatus  40  and a fourth transfer apparatus  50 . 
     In general, the third transfer apparatus  40  may include an apparatus configured to transfer the substrate S in the first direction X in a state in which the substrate S is not aligned, and the fourth transfer apparatus  50  may include an apparatus configured to transfer the substrate S in the first direction X in a state in which the substrate S is aligned. In general, due to the separation distance between the third transfer apparatus  40  and the fourth transfer apparatus  50 , the warped substrate S may be caught between the third transfer apparatus  40  and the fourth transfer apparatus  50  and may not be transferred in the first direction X. Hereinafter, the fifth substrate transfer apparatus  3  according to an example embodiment capable of improving the above-described problems will be described in more detail. 
     In an example embodiment, the third transfer apparatus  40  may be configured to transfer the substrate S in the first direction X and transfer the substrate S to the fourth transfer apparatus  50 . The third transfer apparatus  40  may include a plurality of third rotation shafts  460  and a transfer belt  470  surrounding the third rotation shafts  460 . The substrate S may be transferred in the first direction X through rotation of the third rotation shaft  460 . 
     In an example embodiment, the fourth transfer apparatus  50  may include an apparatus configured to receive the substrate S from the third transfer apparatus  40  and transfer the substrate S in the first direction X. The fourth transfer apparatus  50  may include the supporter  110 , the first rotation shaft  120 , the main transfer roller  130 , the second rotation shaft  140 , the auxiliary transfer roller  150 , the first rotation driver  160 , the second rotation driver  170 , the camshaft  180 , the third rotation driver  190 , the eccentric cam  195 , a conveyor belt  500 , an inclination angle adjuster  530 , a carry-in sensor  570 , and a carry-out sensor  580 , and the like. The technical idea of the supporter  110 , the first rotation shaft  120 , the main transfer roller  130 , the second rotation shaft  140 , the auxiliary transfer roller  150 , the first rotation driver  160 , the second rotation driver  170 , the camshaft  180 , the third rotation driver  190 , and the eccentric cam  195  of the fourth transfer apparatus  50  is substantially the same as that described with reference to  FIG. 9 . Therefore, detailed descriptions thereof will be omitted. 
     In an example embodiment, the conveyor belt  500  may include a belt shaft  510  and a transfer belt  520 . The belt shaft  510  may be configured to rotate, and the transfer belt  520  may support the substrate S and transfer the substrate S in the first direction X. The conveyor belt  500  may be installed adjacent to a carry-in part of the fourth transfer apparatus  50 , but the inventive concept is not limited thereto. Additionally or alternatively, the conveyor belt  500  may be installed in front of the transfer roller  130  and transfer the substrate S received from the third transfer apparatus  40  to the transfer roller  130 . 
     In an example embodiment, referring to  FIG. 15 , the conveyor belt  500  may be inclined upward toward the first direction X. In other words, the conveyor belt  500  may have an inclination angle a. For example, a part of the conveyor belt  500  adjacent to the third transfer apparatus  40  may be at a lower level than the third transfer apparatus  40 , and a part of the conveyor belt  500  adjacent to the transfer roller  130  of the fourth transfer apparatus  50  may be at a higher level than the third transfer apparatus  40 . As a result, when the substrate S is transferred from the third transfer apparatus  40  to the fourth transfer apparatus  50  in a state in which the substrate S is warped in a convex upward shape, a part of the substrate S may be in contact with the conveyor belt  500 . As a result, the substrate S may be transferred in the first direction X without being caught between the third transfer apparatus  40  and the fourth transfer apparatus  50 . 
     In an example embodiment, the inclination angle adjuster  530  may be configured to adjust the inclination angle a formed by the conveyor belt  500 . Additionally or alternatively, the inclination angle adjuster  530  may adjust the inclination angle a formed by the conveyor belt  500  based on the size of the substrate S to be transferred, a degree of warpage of the substrate S, and an abnormal transfer state of the substrate S. For example, the inclination angle adjuster  530  may include an actuator configured to adjust the position of at least one of the plurality of belt shafts  510  in the vertical direction Z. 
     In an example embodiment, the carry-in sensor  570  may include a sensor that detects whether the substrate S is normally carried in into the fourth transfer apparatus  50 , and the carry-out sensor  580  may include a sensor that detects whether the substrate S is normally carried out from the fourth transfer apparatus  5 . 
     In an example embodiment, when the substrate S is not normally carried in into the fourth transfer apparatus  50 , the carry-in sensor  570  may transmit an abnormal carry-in signal to the controller  400 . Additionally or alternatively, when the substrate S is not normally carried out from the fourth transfer apparatus  50 , the carry-out sensor  580  may transmit an abnormal carry-out signal to the controller  400 . 
     The controller  400  may be connected to the carry-in sensor  570 , the carry-out sensor  580 , the third rotation driver  190 , and the inclination angle adjuster  530 . The controller  400  may control at least one of the third rotation driver  190  and the inclination angle adjuster  530  based on signals transmitted from the carry-in sensor  570  and the carry-out sensor  580 . 
     In an example embodiment, when the controller  400  receives the abnormal carry-in signal from the carry-in sensor  570 , the controller  400  may control the inclination angle adjuster  530  to adjust the inclination angle a. However, the inventive concept is not limited thereto, and the controller  400  may adjust the inclination angle a through a separate sensor that senses the size of the substrate S and the degree of warpage of the substrate S. 
     Additionally or alternatively, as described above, when the controller  400  receives the abnormal carry-out signal from the carry-out sensor  580 , the controller  400  may drive the third rotation driver  190  to rotate the eccentric cam  195 . 
       FIG. 16  is a cross-sectional view of a sixth substrate transfer apparatus  4   a , according to an example embodiment. The sixth substrate transfer apparatus  4   a  may include a fifth transfer apparatus  60  and a sixth transfer apparatus  70 . The fifth transfer apparatus  60  may be configured to transfer the substrate S in the first direction X and to transfer the substrate S to the sixth transfer apparatus  70 , and the sixth transfer apparatus  70  may be configured to receive the substrate S from the fifth transfer apparatus  60  and transfer the substrate S in the first direction X. 
     In an example embodiment, the fifth transfer apparatus  60  may include a first lower conveyor belt  700  and a first upper conveyor belt  800 . The first lower conveyor belt  700  and the first upper conveyor belt  800  may cooperate to transfer the substrate S in the first direction X. The first lower conveyor belt  700  may include a first lower rotation shaft  710 , a second lower rotation shaft  720 , a first lower transfer belt  730 , and a lower inclination angle forming shaft  770 . 
     In an example embodiment, the first lower rotation shaft  710  may rotate in a first rotation direction. The first rotation direction may be a rotation direction for transferring the substrate S in the first direction X, and referring to  FIG. 16 , the first rotation direction may be clockwise. 
     The second lower rotation shaft  720  may be spaced apart from the first lower rotation shaft  710  in the first direction X and may rotate in the same direction as the first rotation direction. The first lower transfer belt  730  may connect the first lower rotation shaft  710 , the second lower rotation shaft  720 , and the lower inclination angle forming shaft  770  and may be in contact with a part of the lower surface of the substrate S. 
     The lower inclination angle forming shaft  770  may form a lower inclination angle b in a part of the first lower conveyor belt  700  into which the substrate S is carried in. In other words, the first lower conveyor belt  700  may be inclined upward toward the first direction X in the carry-in part of the substrate S. For example, the lower inclination angle b may be from about 30 degrees to about 60 degrees. As a result, when the substrate S is transferred to the first lower conveyor belt  700  in a convex upward warped state, a part of the substrate S may contact the first lower conveyor belt  700  and may be transferred normally in the first direction X. 
     In an example embodiment, the lower inclination angle forming shaft  770  may be in front of the first lower rotation shaft  710  to form the lower inclination angle b and may be at a lower level than the first lower rotation shaft  710 . 
     The first upper conveyor belt  800  may include a first upper rotation shaft  810 , a second upper rotation shaft  820 , a first upper transfer belt  830 , and an upper inclination angle forming shaft  870 . In an example embodiment, the first upper rotation shaft  810  may rotate in a second rotation direction which is a direction opposite to the first rotation direction. The second rotation direction may be a rotation direction for transferring the substrate S in the first direction X, and referring to  FIG. 16 , the second rotation direction may be counterclockwise. 
     The second upper rotation shaft  820  may be spaced apart from the first upper rotation shaft  810  in the first direction X and may rotate in the same direction as the second rotation direction. The first upper transfer belt  830  may connect the first upper rotation shaft  810 , the second upper rotation shaft  820 , and the upper inclination angle forming shaft  870  and may be in contact with a part of the upper surface of the substrate S. 
     The upper inclination angle forming shaft  870  may form an upper inclination angle c in a part of the first upper conveyor belt  800  into which the substrate S is carried in. In other words, the first upper conveyor belt  800  may be inclined downward toward the first direction X in the carry-in part of the substrate S. For example, the upper inclination angle c may be from about 30 degrees to about 60 degrees. As a result, when the substrate S is transferred to the first upper conveyor belt  800  in a convex downward warped state, a part of the substrate S may contact the first upper conveyor belt  800  and may be transferred normally in the first direction X. 
     In an example embodiment, the upper inclination angle forming shaft  870  may be in front of the first upper rotation shaft  810  to form the upper inclination angle c and may be at a level lower than the first upper rotation shaft  810 . 
     In an example embodiment, as shown in  FIG. 16 , a gap (i.e., a separation distance in the vertical direction Z) in the vertical direction Z between the first lower transfer belt  730  and the first upper transfer belt  830  may be formed uniformly. For example, the gap in the vertical direction Z formed by the first lower transfer belt  730  and the first upper transfer belt  830  in the part where the substrate S is carried in may be substantially the same as the gap in the vertical direction Z formed by the first lower transfer belt  730  and the first upper transfer belt  830  in the part where the substrate S is carried out. The gap in the vertical direction Z formed by the first lower transfer belt  730  and the first upper transfer belt  830  may be adjusted based on the size of the substrate S, a degree of warpage of the substrate S, and the like. 
     In an example embodiment, as shown in  FIG. 16 , the gap between the first lower transfer belt  730  and the first upper transfer belt  830  in the part where the substrate S is carried may be greater than the gap between the first lower transfer belt  730  and the first upper transfer belt  830  in the part where the substrate S is carried out. 
     While the substrate S is transferred in the first direction X through the fifth transfer apparatus  60 , the first lower conveyor belt  700  may apply upward pressure to the substrate S, and the first upper conveyor belt  800  may apply downward pressure to the substrate S. As a result, the warpage of the substrate S may be temporarily increased while the warped substrate S is transferred in the first direction X by the fifth transfer apparatus  60 . 
     The sixth transfer apparatus  70  may include a second lower conveyor belt  900  and a guide roller  950 . The second lower conveyor belt  900  may include a second lower rotating shaft  910  and a second lower transfer belt  930 . 
     The guide roller  950  may include a roller configured to guide the transfer of the substrate S from the fifth transfer apparatus  60  to the sixth transfer apparatus  70 . The guide roller  950  may be spaced apart from the second lower conveyor belt  900  in the vertical direction. Additionally or alternatively, the guide roller  950  may be installed in the carry-in part of the sixth transfer apparatus  70 . 
     In an example embodiment, when the substrate S is transferred from the fifth transfer apparatus  60  to the sixth transfer apparatus  70  in a convex downward state, the substrate S may contact the guide roller  950 . The guide roller  950  may guide the substrate S in the first direction X through a rotation. 
       FIG. 17  is a cross-sectional view of a seventh substrate transfer apparatus  4   b , according to an example embodiment. Hereinafter, redundant descriptions of the sixth substrate transfer apparatus  4   a  of  FIG. 16  and the seventh substrate transfer apparatus  4   b  of  FIG. 17  are omitted, and differences therebetween will be mainly described. 
     Referring to  FIG. 17 , the seventh substrate transfer apparatus  4   b  may further include the controller  400 , the carry-in sensor  570 , the carry-out sensor  580 , a conveyor belt gap adjuster  670 , a lower inclination angle adjuster  790 , an upper inclination angle adjuster  890 , a first swing apparatus  970 , and a second swing apparatus  990 . The technical idea of the controller  400 , the carry-in sensor  570 , and the carry-out sensor  580  is substantially the same as that described above. Therefore, detailed descriptions thereof are omitted. 
     In an example embodiment, the conveyor belt gap adjuster  670  may be configured to adjust a separation distance d 3  in the vertical direction Z between the first lower conveyor belt  700  and the first upper conveyor belt  800 . Additionally or alternatively, the conveyor belt gap adjuster  670  may be configured to adjust the separation distance d 3  in the vertical direction Z between the first lower conveyor belt  700  and the first upper conveyor belt  800  based on the size of the substrate S and a degree of warpage of the substrate S, and the like. 
     In an example embodiment, the lower inclination angle adjuster  790  may be configured to adjust the magnitude of the lower inclination angle b formed by the first lower conveyor belt  700 . Additionally or alternatively, the lower inclination angle adjuster  790  may adjust the magnitude of the lower inclination angle b based on the size of the substrate S and the degree of warpage of the substrate S. For example, the lower inclination angle adjuster  790  may adjust the magnitude of the lower inclination angle b by adjusting the position of the lower inclination angle forming shaft  770  in the vertical inclination Z. 
     In an example embodiment, the upper inclination angle adjuster  890  may be configured to adjust the magnitude of the upper inclination angle c formed by the first upper conveyor belt  800 . Additionally or alternatively, the upper inclination angle adjuster  890  may adjust the magnitude of the upper inclination angle c based on the size of the substrate S and the degree of warpage of the substrate S. For example, the upper inclination angle adjuster  890  may adjust the magnitude of the upper inclination angle c by adjusting the position of the upper inclination angle forming shaft  870  in the vertical direction Z. 
     In an example embodiment, the first swing apparatus  970  may be configured to swing the fifth transfer apparatus  60 . For example, the first swing apparatus  970  may be coupled to at least one of the first lower conveyor belt  700  and the first upper conveyor belt  800 . When the substrate S is caught in the fifth transfer apparatus  60  and is not normally transferred in the first direction X, the first swing apparatus  970  may swing the fifth transfer apparatus  60 . The technical idea of the first swing apparatus  970  is substantially the same as that of the swing apparatus  350  described with reference to  FIG. 1 . Therefore, a detailed description thereof will be omitted. 
     In an example embodiment, the second swing apparatus  990  may be configured to swing the sixth transfer apparatus  70 . For example, the second swing apparatus  990  may be coupled to the second lower conveyor belt  900 . When the substrate S is caught in the sixth transfer apparatus  70  and is not normally transferred in the first direction X, the second swing apparatus  990  may swing the sixth transfer apparatus  70 . The technical idea of the second swing apparatus  990  is substantially the same as that of the swing apparatus  350  described with reference to  FIG. 1 . Therefore, a detailed description thereof will be omitted. 
       FIG. 18  is a flowchart showing operations of a third substrate transfer method S 30 , according to an example embodiment.  FIGS. 19 to 23  are diagrams showing respective operations of the third substrate transfer method S 30 . The third substrate transfer method S 30  may include a method of transferring the substrate S in the first direction X through the seventh substrate transfer apparatus  4   b  of  FIG. 16 . 
     Referring to  FIG. 18 , the third substrate transfer method S 30  may include operation S 310 , S 320 , S 330 , S 340 , S 350 , S 360 , and S 370 . Operation S 310  may carry in the substrate S into the fifth transfer apparatus  60 . Operation S 320  may determine whether the substrate S is normally carried in into the fifth transfer apparatus  60 . Operation S 330  may swing the fifth transfer apparatus  60 . Operation S 340  may transfer the substrate S through the fifth transfer apparatus  60 . Operation S 350  may determine whether the substrate S is normally carried in into the sixth transfer apparatus  70 . Operation S 360  may swing the sixth transfer apparatus  70 . Operation S 370  may transfer the substrate S through the sixth transfer apparatus  70 . 
     Referring to  FIGS. 18 and 19  together, operation S 310  may be an operation of carrying in the substrate S into the fifth transfer apparatus  60 . Additionally or alternatively, in operation S 310 , the controller  400  may control the conveyor belt gap adjuster  670  to adjust the separation distance d 3  between the first lower conveyor belt  700  and the first upper conveyor belt  800  in the vertical direction Z based on the size of the substrate S and a degree of warpage of the substrate S. 
     Additionally or alternatively, in operation S 310 , the controller  400  may control the lower inclination angle adjuster  790  and the upper inclination angle adjuster  890  to adjust the lower inclination angle b and the upper inclination angle c respectively based on the size of the substrate S and the degree of warpage of the substrate S. 
     Referring to  FIGS. 18 and 20  together, operation S 320  may be an operation in which the controller  400  determines whether the substrate S is normally carried in into the fifth transfer apparatus  60 . In an example embodiment, in operation S 320 , when the substrate S is not normally carried into the fifth transfer apparatus  60 , the carry-in sensor  570  may generate an abnormal carry-in signal and transmit the abnormal carry-in signal to the controller  400 . When the controller  400  receives the abnormal carry-in signal, the controller  400  may determine that the substrate S is not normally carried in into the fifth transfer apparatus  60 . 
     In an example embodiment, when the substrate S is caught in the first lower conveyor belt  700 , the carry-in sensor  570  may transmit a first abnormal carry-in signal to the controller  400 . Additionally or alternatively, when the substrate S is caught in the first upper conveyor belt  800 , the carry-in sensor  570  may transmit a second abnormal carry-in signal to the controller  400 . 
     Operation S 330  may be an operation in which the controller  400  swings at least one of the first lower conveyor belt  700  and the first upper conveyor belt  800  through the first swing apparatus  970 . 
     In an example embodiment, when the controller  400  receives the first abnormal carry-in signal, the controller  400  may control the first swing apparatus  970  to swing the first lower conveyor belt  700 . Additionally or alternatively, when the controller  400  receives the second abnormal carry-in signal, the controller  400  may control the first swing apparatus  970  to swing the first upper conveyor belt  800 . 
     Referring to  FIGS. 18 and 21  together, operation S 340  may be an operation of transferring the substrate S in the first direction X by the fifth transfer apparatus  60 . In operation S 320 , the first lower conveyor belt  700  may apply upward pressure to the substrate S, and the first upper conveyor belt  800  may apply downward pressure to the substrate S. As a result, while the warped substrate S is transferred in the first direction X by the fifth transfer apparatus  60 , the warpage of the substrate S may be increased. 
     Referring to  FIGS. 18 and 22  together, operation S 350  may be an operation in which the controller  400  determines whether the substrate S is normally carried in into the sixth transfer apparatus  70 . In an example embodiment, in operation S 350 , when the substrate S is carried out from the fifth transfer apparatus  60  and is not normally carried in into the sixth transfer apparatus  70 , the carry-out sensor  580  may generate an abnormal carry-out signal and transmit the abnormal carry-out signal to the controller  400 . 
     When the controller  400  receives the abnormal carry-out signal, the controller  400  may determine that the substrate S is not normally carried in into the sixth transfer apparatus  70 . For example, when the substrate S is caught in the second lower conveyor belt  900 , the carry-out sensor  580  may transmit the abnormal carry-out signal to the controller  400 , and the controller  400  may determine that the substrate S is not normally carried in into the sixth transfer apparatus  70 . 
     Operation S 360  may be an operation in which the controller  400  swings the second lower conveyor belt  900  through the second swing apparatus  990 . In an example embodiment, when the controller  400  receives the abnormal carry-out signal, the controller  400  may control the second swing apparatus  990  to swing the second lower conveyor belt  900 . 
     Referring to  FIGS. 18 and 23  together, operation S 350  may be an operation of transferring the substrate S in the first direction X through the sixth transfer apparatus  70 . The substrate S may be carried in into a process chamber through the sixth transfer apparatus  70  for a substrate processing process. However, the inventive concept is not limited thereto, and the substrate S may be carried out from the chamber through the sixth transfer apparatus  70 . 
     The third substrate transfer method S 30  according to an example embodiment may prevent a catching phenomenon of the substrate S, thereby improving the substrate transfer speed, and preventing damage to the substrate S. Additionally or alternatively, the third substrate transfer method S 30  may transfer the substrate S through the first lower conveyor belt  700  and the first upper conveyor belt  800  configured to apply pressure to the upper and lower portions of the substrate S respectively, thereby reducing the warpage of the substrate S. 
     While the inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.