Patent Publication Number: US-2023134909-A1

Title: Defect inspection system and semiconductor fabrication apparatus including a defect inspection apparatus using the same

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. § 119(a) to Korean patent application number 10-2021-0150810, filed on Nov. 4, 2021, in the Korean Intellectual Property Office, which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     Various embodiments generally relate to a semiconductor fabrication technology, more particularly, to a defect inspection system and a semiconductor fabrication apparatus including a defect inspection apparatus using the same. 
     2. Related Art 
     Generally, during performing semiconductor fabrication processes, various defects such as an organic contaminant, a metal impurity, a scratch, a crack, a chipping, a breakage, etc., may be generated at a semiconductor substrate. The defects may be inspected by using a macro inspection or an in-line automatic optical inspection after performing each of the semiconductor fabrication processes. 
     SUMMARY 
     According to example embodiments, there is provided a defect inspection system. The defect inspection system may include an information-obtaining module and a defect inspection module. The information obtaining module may be arranged over a transferring apparatus to continuously photograph a surface of a substrate transferred by the transferring apparatus. The defect inspection module may generate an image signal based on information of the substrate provided from the information-obtaining module. The defect inspection module may compare the image signal with a reference to detect a defect of the substrate. 
     In example embodiments, the information-obtaining module may include a light source and an optical detector. The light source may be configured to irradiate an incident light to the substrate. The optical detector may collect a reflected light from the substrate to generate an electrical signal with respect to the reflected light. 
     In example embodiments, the information-obtaining module may further include an optical path changer. The optical path changer may be arranged between the substrate and the optical detector to change an optical path of the reflected light toward the detector. 
     In example embodiments, the light source may control an incident angle of the incident light based on a position of the defect on the substrate. 
     In example embodiments, the light source may include a plurality of sub-light sources. At least one of wavelengths, incident lights and lighting times of the sub-light sources may be different from each other. Further, the sub-light sources may irradiate the incident light to different substrates. 
     In example embodiments, the defect inspection module may include an image signal generator, a storage and a defect determining member. The image signal generator may generate the image signal using the information of the substrate provided from the information-obtaining module. The storage may store information of a normal substrate and information of a defect in a previous substrate as a reference. The defect determining member may compare the image signal with the reference to generate a defect detection signal. 
     According to example embodiments, there may be provided a semiconductor fabrication apparatus. The semiconductor fabrication apparatus may include first and second process chamber, a load-lock chamber and a transfer chamber. The load-lock chamber may be configured to receive a plurality of substrate to be loaded into the first process chamber or the second process chamber. The transfer chamber may be arranged between the first process chamber, the second process chamber and the load-lock chamber to transfer the substrates to the first process chamber, the second process chamber or the load-lock chamber. 
     In example embodiments, the semiconductor fabrication apparatus may further include a defect inspection apparatus arranged in the transfer chamber. The defect inspection apparatus may detect a defect of the substrate transferred in the transfer chamber based on an image signal of the substrate. 
     In example embodiments, the defect inspection apparatus may include a continuous photographer configured to continuously photograph at least a portion of the substrate. The continuous photographer may accumulate photographed signals to output a continuous image signal. 
     In example embodiments, the defect inspection apparatus may further include an illuminator configured to provide the continuous photographer with an illumination light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of the subject matter of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a view illustrating a defect inspection system in accordance with example embodiments; 
         FIG.  2    is a view illustrating a method of inspecting a defect in accordance with example embodiments; 
         FIGS.  3  and  4    are views illustrating an operation of an optical path changer in accordance with example embodiments; 
         FIG.  5    is a block diagram illustrating a semiconductor fabrication apparatus in accordance with example embodiments; 
         FIG.  6    is a side view illustrating a semiconductor fabrication apparatus in accordance with example embodiments; 
         FIGS.  7 A and  7 B  are views illustrating a defect inspection apparatus in accordance with example embodiments; 
         FIG.  8    is a view illustrating a defect inspection apparatus in accordance with example embodiments; and 
         FIG.  9    is a view illustrating a method of inspecting a defect in accordance with example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the present invention will be described in greater detail with reference to the accompanying drawings. The drawings are schematic illustrations of various embodiments (and intermediate structures). As such, variations from the configurations and shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, the described embodiments should not be construed as being limited to the particular configurations and shapes illustrated herein but may include deviations in configurations and shapes which do not depart from the spirit and scope of the present invention as defined in the appended claims. 
     The present invention is described herein with reference to cross-section and/or plan illustrations of idealized embodiments of the present invention. However, embodiments of the present invention should not be construed as limiting the inventive concept. Although a few embodiments of the present invention will be shown and described, it will be appreciated by those of ordinary skill in the art that changes may be made in these embodiments without departing from the principles and spirit of the present invention. 
       FIG.  1    is a view illustrating a defect inspection system in accordance with example embodiments and  FIG.  2    is a view illustrating a method of inspecting a defect in accordance with example embodiments. 
     Referring to  FIGS.  1  and  2   , a defect inspection system  10  of example embodiments may detect a defect of a substrate in real time. The defect inspection system  10  may include an information-obtaining module  100 , an interface  180 , a defect inspection module  200 , a power supply module  300  and a control module  400 . 
     The information-obtaining module  100  may include a light source  110 , an optical detector  130  and an optical path changer  150 . 
     The light source  110  may irradiate an incident light L 1  to a surface of the substrate W. In example embodiments, the substrate W may include a bare wafer, a wafer with at least one layer, etc. The incident light L 1  may be incident to the surface of the substrate W at an angle θ. The incident light L 1  may then be reflected from the surface of the substrate W. A reference numeral L 2  may indicate the reflected light from the surface of the substrate W. For example, the light source  110  may be arranged at a semiconductor fabrication apparatus positioned on a transferring direction of the substrate W, or a semiconductor fabrication apparatus configured to perform the following process. 
     The light source  110  may include a light source including a scanning type, a light emitting diode (LED), a mixed light source including a plurality of beams having different characteristics, and a combination thereof. 
     For example, when the incident light L 1  may have a line shape or a stripe shape, the incident light L 1  may be focused on an inspection region of the substrate W. Thus, unnecessary noises may be reduced in an inspection process. 
     The light source  110  may irradiate the incident light L 1  using a scanning tech. The incident light L 1  irradiated by the light source  110  may have at least one wavelength. For example, wavelengths of the incident light L 1  may be selected based on properties of the surface of the substrate W, for example, properties of the inspection region of the substrate W. In order to generate the incident light L 1  having multi-wavelengths, the light source  110  may include a plurality of sub-light sources. The sub-light sources may be selectively or simultaneously driven. For example, when the inspection region may include a metal layer formed on the substrate W, the light source  110  may irradiate the incident light L 1  having a wavelength of about 680 nm to about 780 nm. When the inspection region may include a silicon nitride layer, the light source  110  may irradiate the incident light L 1  having a wavelength of about 480 nm to about 580 nm. When the inspection region may include a silicon oxide layer, the light source  110  may irradiate the incident light L 1  having a wavelength of about 380 nm to about 480 nm. For example, an optimal sub-light source among the sub-light sources may be selected in accordance with the kinds and thicknesses of the inspection region. The selected sub-light source may irradiate the incident light L 1 . 
     The light source  110  may include a white light source, a blue light source and a yellow light source. Any one of the white light source, the blue light source and the yellow light source may be selected in accordance with a previous process which is performed immediately prior to this defect inspection process. For example, when the previous process includes a photolithography process, the yellow light source may be selected. When the previous process includes a diffusion process, the blue light source may be selected. However, the light source  110  having various wavelengths and various colors may be selected without the above-mentioned conditions. 
     The light source  110  may control an incident angle of the incident light L 1  with respect to the surface of the substrate W from about 0 to about 90°. The light source  110  may include a plurality of sub-light sources, and the incident lights emitted from the sub-light sources may have same or different incident angles. 
     The light source  110  may irradiate the incident light L 1  to the successively transferred substrates W. For example, when the light source  110  includes a first sub-light source and a second sub-light source, and a first substrate and a second substrate are successively loaded in a transfer chamber, the first sub-light source may irradiate the incident light L 1  having a first incident angle to the first substrate. The second sub-light source may irradiate the incident light L 1  having a second incident angle to the second substrate. The second incident angle of the second sub-light source may be controlled based on a defect position of the first substrate and the first incident angle of the first sub-light source. Irradiation times of the incident lights L 1  by the first sub-light source and the second sub-light source may be substantially the same or different from each other. For example, the irradiation time of the incident light L 1  to the second substrate may be controlled based on the defect of the first substrate. 
     The optical detector  130  may collect the reflected light L 2  from the substrate W. For example, the optical detector  130  may include a detection element such as a charge coupled device (CCD), a CMOS image sensor (CIS), a photomultiplier tube, an avalanche detector, a photodiode detector, a strak camera, a silicon detector, an area scan camera, a line scan camera, etc. The CIS may include a time delay integration (TDI) pixel array and a region detection CCD pixel array. The area scan camera may detect a colored defect or a defect of a colored substrate. The line scan camera may detect several micrometers of defects. The line scan camera may collect the reflected light L 2  by a TDI scanning. The line scan camera may be referred to as a TDI camera. The TDI camera may photograph the inspection region of the substrate W several times. The TDI camera may overlap information of captured images with each other to generate an overlap signal. For example, the TDI camera may successively photograph from an initial photograph point to a last photograph point of the substrate W transferred at a constant speed. The TDI camera may accumulate collected signals by the photographing to collect the image information having a high resolution, thereby detect nanometers of the defect. The TDI camera may include at least one optical element such as a lens. 
     In example embodiments, the optical detector  130  may include a plurality of image sensors, a TDI camera and an area scan camera. 
     Further, the optical detector  130  may be configured to generate an electrical signal corresponding to the reflected light L 2  based on an intensity of the reflected light L 2  using the image sensors or the TDI camera. The optical detector  130  may receive the reflected light L 2  from the transferred substrate W as an optical signal. The optical detector  130  may convert the analog signal into an electrical signal. 
     The optical detector  130  may successively receive the reflected lights L 2  from the successively transferred substrates W. The optical detector  130  may generate electrical signals with respect to the reflected lights L 2  from the substrates W. The optical detector  130  may then transmit the electrical signals to the defect inspection module  200 . 
     The optical detector  130  may be placed at a position spaced apart from the surface of the substrate W. The optical detector  130  may be fixed to a specific position. Alternatively, the optical detector  130  may be moved along the transferring direction of the substrate W. 
     The optical detector  130  may include a plurality of detection elements for successively receiving the reflected lights L 2  from the substrates W. The optical detector  130  may output a detection signal having a binary code based on the reflected light L 2 . 
     The optical path changer  150  may be arranged between the optical detector  130  and the substrate W. The optical path changer  150  may change an optical path of the reflected light L 2 . The optical path changer  150  may change the optical path so that the reflected lights L 2  traveling in various directions are focused on the optical detector  130 . For example, the optical path changer  150  may reflect or refract the reflected lights L 2  having various diagonal directions with respect to the surface of the substrate W toward the optical detector  130 . The optical path changer  150  may include a prism. In  FIG.  2   , a reference numeral “A” may indicate an average inclined angle between the incident light L 1  and the reflected light L 2 . When the inclined angle A may be about 45° to about 135°, the intensity of the reflected light L 2  may be a maximum value. The inclined angle A may be corrected by the optical path changer  150 . 
       FIGS.  3  and  4    are views illustrating an operation of an optical path changer in accordance with example embodiments. 
     Referring to  FIG.  3   , the optical path changer  150  may include a plurality of optical surfaces  151   a  to  151   d . For example, the optical path changer  150  may include an incidence surface  151   a , an exit surface  151   b , a reflection surface  151   c  and a side surface  151   d  configured to contact the incidence surface  151   a , the exist surface  151   b  and the reflection surface  151   c . The optical path changer  150  may control the inclined angle A by changing positions of the incidence surface  151   a , the exit surface  151   b , the reflection surface  151   c  and the side surface  151   d.    
     The incidence surface  151   a , the exit surface  151   b  and the reflection surface  151   c  may have quadrangular shapes having different sizes. A light exiting from the optical path changer  150  may be progressed in a direction substantially perpendicular to a surface of the exit surface  151   b.    
     When the incident angle of the incident light L 1  to the substrate W is about 45° to about 60°, the position of the optical path changer  150  may be adjusted to provide the inclined angle A between a normal line C 1 , which may be substantially perpendicular to an incidence surface of the incident light L 1  and the surface of the substrate W, and a progressing direction C 2  of the exiting light with about 75° to about 135°, thereby effectively concentrating the reflected light L 2  on the optical detector  130 . 
     When the incident angle of the incident light L 1  to the substrate W is about 35° to about 55°, the position of the optical path changer  150  may be adjusted to provide the inclined angle A between the normal line C 1  and the progressing direction C 2  of the exiting light with about 45° to about 105°. 
     The optical detector  130  may further include an intensity measurer  132  for measuring intensity of the reflected light L 2 . The intensity measurer  132  may detect a maximum section of the intensity of the reflected light L 2 . 
     The control module  400  may receive the information of the incident light L 1  provided from the light source  110  and the information of the maximum intensity of the reflected light L 2  provided from the intensity measurer  132  in the optical detector  130 . The control module  400  may control the position of the optical path changer  150  based on the information of the incident light L 1  and the information of the maximum intensity of the reflected light L 2 . 
     The position change of the optical path changer  150 , i.e., a rotation of the optical path changer  150  may be performed by a first driver  153  and a second driver  155 . The first driver  153  and the second driver  155  may face each other with respect to the side surface  151   d  of the optical path changer  150 . Each of the first driver  153  and the second driver  155  may include a north polar magnet and a south polar magnet. For example, the first driver  153  may include the north polar magnet and the south polar magnet which are sequentially stacked. The second driver  155  may include the north polar magnet and the south polar magnet arranged side by side. The optical path changer  150  may be rotated toward the Al direction by driving at least one of the first driver  153  and the second driver  155 . 
     A reference numeral “P” may indicate patterns on the substrate W. When the exit surface  151   b  of the optical path changer  150  is parallel to an extending direction of the patterns P, the information of the defect in the pattern P may be readily obtained. 
     As shown in  FIGS.  3  and  4   , the patterns P may be extended in one direction. Alternatively, the patterns P may be extended in various directions. Further, as shown in  FIG.  4   , the substrate W tilted in a direction D 1  may be transferred. When the patterns P may be extended in the various directions or the tilted substrate W may be transferred, the position of the exit surface  151   b  may be controlled in accordance with a tilted angle of the substrate W, an extending direction of an uppermost patterns, or extending directions of the patterns. In this case, the first and second drivers  153  and  155  may be simultaneously driven to change the position of the optical path changer  150  toward the A 1  direction and the A 2  direction. The first and second drivers  153  and  155  may be driven based on a control signal provided from the control module  400 . The control signal may be inputted into the first and second drivers  153  and  155  through the interface  180 . 
     The optical information of the substrate W collected by the information-obtaining module  100  may be transmitted to the defect inspection module  200  and the control module  400  through the interface  180 . The interface  180  may be directly or indirectly connected between the information-obtaining module  100 , the defect inspection module  200 , the power supply module  300  and the control module  400  to transmit the signals between the modules. 
     The defect inspection module  200  may determine whether the defect may exist in the substrate W or not based on the optical information provided from the information-obtaining module  100 . 
     The defect inspection module  200  may include an image generator  210 , a storage  230  and a defect determining member  250 . The defect inspection module  200  may further include a pre-processing member  270  and a display  290 . 
     The image generator  210  may process the optical information transmitted through the interface  180  to generate the image signal. The image generator  210  may receive and amplify the electrical signal collected by the information-obtaining module  100 , i.e., the digital signal to output the image signal of the substrate W. For example, the image signal may be generated based on electrical signals based on pixels of the CIS. The image generator  210  may be substantially the same as an image processing circuit of a general photoelectric device. 
     The storage  230  may store the image signal generated from the image generator  210  based on the optical information collected by the information-obtaining module  100 . The storage  230  may store an image signal generated based on optical information of the substrate without a defect and the optical information. 
     Therefore, the storage  230  may provide the optical information and the image signal of the substrate W without the defect or the optical information and the image signal of the previously transferred substrate as a reference. 
     The storage  230  may include a computer readable medium. The computer readable medium may be any one of various non-transitory computer readable media. The storage  230  may transmit the stored information to a management server or a terminal of a manager. The non-transitory computer readable medium may be configured to semi-permanently store data. The non-transitory computer readable medium may be readable by a device. For example, the non-transitory computer readable medium may include a CD, a DVD, a hard disk, a blue-ray disk, a USB, a memory card, an ROM, etc. 
     The defect determining member  250  may compare the image signal with the reference to determine the defect of the substrate W. For example, the optical information and the image signal may be classified into pixel units of the optical detector  130 . Thus, the defect determining member  250  may compare the image signal or the optical information classified by position of the pixels with the image signal or the optical information corresponding to the reference to determine the defect in a specific position of the substrate W. Further, the defect determining member  250  may consider other environmental factors, for example, illumination intensity besides the defect to output the defect detection signal. 
     The defect determining member  250  may determine the defect by the pixel using a line profile method. The line profile method may represent a characteristic of an image as a line. The line profile method may analyze an image entirely or a specific section of the image. The defect determining member  250  may analyze the line for representing the characteristics of the image to recognize an initial coordinate of the unit pixel, not limited thereto. The defect determining member  250  may detect various defects such as a contaminant, an impurity, a scratch, a crack, a chipping, a breakage, etc., based on intensity, a color, a size, luminance and brightness of the image signal. For example, when the defect may be detected under a condition that the incident angle θ of the incident light may be about 45° to about 60°, a distortion of the reflected light L 2  may be more increased by providing the incident angle θ with about 35° to about 55°. In this case, the defect may be determined as a protrusive defect, for example, a contaminant. When a distortion may not be generated in the reflected light L 2  although a difference between the reflected light L 2  and the reference, this defect may be determined as a defect in the substrate, for example, a crack. 
     The defect detection signal generated from the defect determining member  250  may be transmitted to the control module  400 . The control module  400  may determine the kinds and positions of the defects. The control module  400  may determine a following process of the substrate W and a following inspection condition of the following substrate W, for example, driving conditions of the light source  110 , the optical detector  130  and the optical path changer  150 . 
     The pre-processing member  270  may correct distorted information of the image signals of the reference and the substrate W, for example, noises having no influence on the defect detection to analyze the defect more accurately. The pre-processing member  270  may match the scanning direction of the substrate W with the scanning direction of the reference to coincide the scanning directions of the substrate W and the reference with each other. 
     The display  290  may display defect detection results in accordance with the defect detection signal. The defect detection results may be outputted through a user interface (UI) or a graphic user interface (GUI). 
     The power supply module  300  may provide power to the modules  100 ,  180 ,  200  and  400  in the system  10 . 
     The control module  400  may control the modules  100 ,  180 ,  200  and  300  in the system  10 . For example, the control module  400  may receive a defect detection signal from the defect detection module  200  to determine the position, the size and the kind of the defect. The control module  400  may then generate the defect detection result based on the determined results. The control module  400  may then transmit the defect detection result to the display  290 . The defect detection result may include a rework or a scrapping of the substrate W as well as the defect information. Thus, performing the following process with respect to the substrate W may be determined based on the defect detection result. 
     Further, in order to accurately determine whether a defect generated in a previous substrate W may be generated in the following substrate W or not based on the defect detection result, the control module  400  may control the operation conditions of the light source  110 , the optical detector  130  and the optical path changer  150 . 
     The control module  400  may include a micro-processor. The control module  400  may be connected with the modules through a wire communication or a wireless communication. The control module  400  may further generate a fault detection collection (FDC) interlock signal based on the defect detection result. Thus, when a serious defect may be generated in the substrate W, the following process may not be performed on the substrate W so that an interlock may be performed. 
       FIG.  5    is a block diagram illustrating a semiconductor fabrication apparatus in accordance with example embodiments and  FIG.  6    is a side view illustrating a semiconductor fabrication apparatus in accordance with example embodiments. 
     Referring to  FIGS.  5  and  6   , a semiconductor fabrication apparatus  20  may include a first process chamber CH 1 , a second process chamber CH 2 , a transfer chamber TC, a load-lock chamber LC and a defect inspection apparatus  50   a.    
     The first process chamber CH 1  and the second process chamber CH 2  may perform a same process or different processes. 
     The load-lock chamber LC may be configured to receive a plurality of substrates W to be processed or processed substrates W. The substrates W may be received in a front opening unified pod (FOUP) F. 
     The transfer chamber TC may be arranged between the first process chamber CH 1 , the second process chamber CH 2  and the load-lock chamber LC. The transfer chamber TC may include at least one transferring member  30  such as a robot arm, a conveyor belt, etc. For example, the transferring member  30  may sequentially transfer the substrate W on which a first process may be performed in the first process chamber CH 1  or a second process may be performed in the second process chamber CH 2  to the FOUP F in the load-lock chamber LC. The transferring member  30  may transfer the semiconductor substrate W in the FOUP F of the load-lock chamber LC to the first process chamber CH 1  or the second process chamber CH 2 . A chamber wall CW may be arranged between the transfer chamber TC and the first process chamber CH 1  and between the transfer chamber TC and the second process chamber CH 2 . A gate G may be arranged at the chamber wall CW. The substrate W may be transferred through the gate G. 
     The defect inspection apparatus  50   a  may be arranged in the transfer chamber TC. The defect inspection apparatus  50   a  may include the parts of the defect inspection system  10  in  FIG.  1   . The defect inspection apparatus  50   a  may be spaced apart from the surface of the substrate W which is inside the transfer chamber TC. In order to line scan all the surface of the transferred substrate W, the defect inspection apparatus  50   a  may be positioned at a front of and/or above the transferred substrate W. 
     The defect inspection apparatus  50   a  may include a successive photographer  55 . The successive photographer  55  may successively photograph the substrate W in a line shape. The successive photographer  55  may accumulate photographed signals to output a successive image signal. The successive photographer  55  may include the configurations of the optical detector  130  and the image signal generator  210  in  FIG.  1   . The successive photographer  55  may include the TDI camera. Additionally, at least one optical lens may be provided to a front of the TDI camera. The defect inspection apparatus  50   a  may further include an illuminator  52  for outputting the image signal having the high resolution from the successive photographer  55 . The illuminator  52  may correspond to the light source  110  in  FIG.  1   . The illuminator  52  may provide the photograph region of the successive photographer  55  with an illumination light to improve focusing characteristics of the successive photographer  55 . The illuminator  52  may control an incident angle of the illumination light. The illuminator  52  may include a plurality of sub-light sources  52   a  and  52   b . At least one of an incident angle, an intensity of illumination and a wavelength of the sub-light sources  52   a  and  52   b  may be different from each other. The sub-light sources  52   a  and  52   b  may be selectively turned-on. Flickering times (on/off operation times) of the sub-light sources  52   a  and  52   b  may be different from each other. 
       FIGS.  7 A and  7 B  are views illustrating a defect inspection apparatus in accordance with example embodiments. 
     Referring to  FIG.  7 A , the successive photographer  55  and the illuminator  52  of the defect inspection apparatus  50  may be in a slant orientation relative to the surface of the substrate W. The successive photographer  55  may be movably arranged to photograph various regions of the substrate W. 
     Referring to  FIG.  7 B , the defect inspection apparatus  50  may include a first successive photographer  55   a , a second successive photographer  55   b  and an illuminator  52 . The first successive photographer  55   a  may be substantially perpendicular to the surface of the substrate W. The second successive photographer  55   b  may be slant to the surface of the substrate W. Thus, the first and second successive photographers  55   a  and  55   b  may be placed at different positions to photograph different regions of the substrate W. 
     Therefore, the various side surface of the substrate W may be photographed by changing the positions of the successive photographers  55 ,  55   a  and  55   b  to detect the defects having various shapes. 
     Referring again to  FIG.  6   , the defect inspection apparatus  50   a  may further include the optical path changer  150  configured to change the optical path of the reflected light from the substrate W, thereby concentrating the reflected light on the successive photographer  55 . The optical path changer  150  may have a configuration substantially the same as the configuration of the optical path changer  150  in  FIG.  1   . 
       FIG.  8    is a view illustrating a defect inspection apparatus in accordance with example embodiments. 
     Referring to  FIG.  8   , the successive photographer  55  may face the exit surface  151   b  of the optical path changer  150 . The first sub-light source  52   a  may be arranged at the first side surface  151   d  of the optical path changer  150 . The second sub-light source  52   b  may be arranged at the second side surface  151   d  of the optical path changer  150 . Thus, the sub-light sources  52   a  and  52   b  may be located at different positions with respect to the substrate W. The sub-light sources  52   a  and  52   b  may be simultaneously turned-on to improve the resolution of the successive photographer  55 . 
     The storage  230  and the defect determining member  250  of the defect inspection module  200  in  FIG.  1    may be provided to the control module  400 . Thus, the control module  400  with the storage  230  and the defect determining member  250  may compare the image signal received from the successive photographer  55  with the image signal of the reference in the storage  230  to generate the defect detection signal. 
       FIG.  9    is a view illustrating a method of inspecting a defect in accordance with example embodiments. 
     Referring to  FIG.  9   , in operation S 1 , a first image signal of the surface of the substrate W may be generated. The first image signal may be generated in the transfer chamber TC during the time when the substrate W may be transferred from the load-lock chamber LC to the first process chamber CH 1 . The first image signal may be an image signal before the substrate W may be processed. The first image signal may be generated by the operations of the information-obtaining module  100  and the defect inspection module  200  in  FIG.  1   . Further, the first image signal may be generated by the defect inspection apparatus  50   a  in  FIG.  6   . 
     In operation S 2 , the first process may be performed on the substrate W. The first process may be performed in the first process chamber CH 1 . 
     In operation S 3 , a second image signal of the substrate W on which the first process may be performed may be generated. The second image signal may be generated by the information-obtaining module  100  and the defect inspection module  200  in the transfer chamber TC or by the defect inspection apparatus  50   a  in  FIG.  6   . 
     In operation S 4 , the defect detection signal may be generated based on the second image signal. The defect detection signal may be generated from the defect inspection module  200  or the control module  400  including the defect determining member  250 . The defect detection signal may be compared with the first and second image signals. When a difference between the signals may be beyond a critical range, the defect detection signal may be outputted. Further, the defect detection signal may be compared with the reference image signal and the second image signal. When a difference between the signals may be beyond a critical range, the defect detection signal may be outputted. 
     In operation S 5 , whether the second process may be performed or not may be determined based on the defect detection signal. 
     When the defect can be repaired based on the defect detection signal, in operation S 6 , the second process may be performed on the substrate W. In contrast, when the defect cannot be repaired based on the defect detection signal, in operation S 7 , the substrate W may be scrapped. 
     When a repair process may be performed before the second process, the defect inspection process may be performed between the repair process and the second process. 
     A critical condition, i.e., a defect determination index for determining performing the second process, performing the repair process or scrapping the substrate W may include numbers, sizes, kinds, etc., of the defect. The distortion caused by the defect may be measured by a mean square error (MSE) between the reference image signal and the inspection image signal. 
     The numbers of the defect may be numbers of independently detected defects. A defect in at least one pixel caused by a single reason may be set as one. The size of the defect may be based on numbers of the pixel with the defect. The kinds of the defect may be determined from the shape of the distorted reflected light. 
     According to example embodiments, the defect inspection method may be performed during the transfer of the substrate. Thus, it may not be required to perform an additional inspection process. Further, the defect inspection method may be performed with respect to all the semiconductor fabrication processes. Therefore, a time for manufacturing the semiconductor device may be remarkably reduced. Further, the defect may be checked in real time after the unit process. As a result, a rapid correspondence with respect to the defect may be performed by each of the processes. 
     The above described embodiments of the present invention are intended to illustrate and not to limit the present invention. Various alternatives and equivalents are possible. The invention is not limited by the embodiments described herein. Nor is the invention limited to any specific type of semiconductor device. Other additions, subtractions, or modifications are obvious in view of the present disclosure and are intended to fall within the scope of the appended claims.