Abstract:
An apparatus and method for cleaning semiconductor wafer are provided. The apparatus includes a brush module, a swing arm, a rotating actuator and an elevating actuator. The brush module has a brush head for providing mechanical force on a surface of a wafer. An end of the swing arm mounts the brush module. The rotating actuator is connected with the other end of the swing arm. The rotating actuator drives the swing arm to swing across the whole surface of the wafer, which brings the brush head moving across the whole surface of the wafer. The elevating actuator is connected with the other end of the swing arm. The elevating actuator drives the swing arm to rise or descend, which brings the brush module rising or descending. The apparatus cleans the semi-conductor wafer by means of the brush head, which improves the cleaning effect.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to a field of cleaning technique for semiconductor wafer, and more particularly relates to an apparatus and method for cleaning semiconductor wafer by means of physical cleaning, such as brush cleaning. 
         [0003]    2. The Related Art 
         [0004]    During the process of semiconductor devices manufacturing, almost every working procedure involves cleaning, and the higher the integration level of the semiconductor devices is, the more cleaning procedures are needed. In many of the cleaning procedures, as long as one cleaning procedure is not able to meet requirement, the whole batch of chips are scrapped. Therefore, cleaning is very important for manufacture of semiconductor devices. 
         [0005]    Contaminants which are produced and adhered to a wafer during manufacturing the semiconductor device mainly include particles, metal contaminants and organic contaminants. At present, a traditional method for removing the contaminants on the wafer is wet cleaning or dry cleaning. Wet cleaning employs chemical solutions or deionized water to rinse the wafer so as to effectively remove the contaminants, while dry cleaning employs gases to remove the contaminants remained on the wafer. Either wet cleaning or dry cleaning mainly relies on chemical reaction to remove the contaminants and doesn&#39;t utilize physical force acted on the wafer surface. However, with the structure of the semiconductor devices becoming more complex, the cleaning requirements of the wafer surface accordingly becomes higher and higher. The traditional cleaning apparatus and method no longer meet process requirement. Therefore, an improved apparatus and method for cleaning semiconductor wafer need to be created out to meet the demands of the development of the semiconductor technology. 
       SUMMARY 
       [0006]    The present invention provides an apparatus and method for cleaning semiconductor wafer by means of a brush head, which improves the cleaning effect and meets the demands of the development of the semiconductor technology. 
         [0007]    According to the present invention, an apparatus for cleaning semiconductor wafer includes a brush module, a swing arm, a rotating actuator and an elevating actuator. The brush module has a brush head for providing mechanical force on a surface of a wafer. An end of the swing arm mounts the brush module. The rotating actuator is connected with the other end of the swing arm. The rotating actuator drives the swing arm to swing across the whole surface of the wafer, which brings the brush head moving across the whole surface of the wafer. The elevating actuator is connected with the other end of the swing arm. The elevating actuator drives the swing arm to rise or descend, which brings the brush module rising or descending. 
         [0008]    According to the present invention, a method for cleaning semiconductor wafer includes the following steps: loading a wafer on a wafer chuck and rotating the wafer; delivering cleaning chemicals or de-ionized water to the surface of the wafer; moving a brush module into a cleaning chamber and a brush head of the brush module being above the surface of the wafer; moving the brush module down to a position close to the surface of the wafer at a first speed; moving the brush module down to a process position with a preset height at a second speed; swinging the brush head of the brush module across the surface of the wafer based on a pre-set recipe; moving the brush module up to a position above the wafer; swinging the brush module out of the cleaning chamber; stopping delivering cleaning chemicals or de-ionized water to the surface of the wafer; drying the wafer; and unloading the wafer from the wafer chuck. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will be apparent to those skilled in the art by reading the following description of embodiments thereof, with reference to the attached drawings, in which: 
           [0010]      FIG. 1A  illustrates an apparatus for cleaning semiconductor wafer according to an exemplary embodiment of the present invention. 
           [0011]      FIG. 1B  illustrates an apparatus for cleaning semiconductor wafer according to another exemplary embodiment of the present invention. 
           [0012]      FIGS. 2A and 2B  illustrate an apparatus for cleaning semiconductor wafer according to further another exemplary embodiment of the present invention. 
           [0013]      FIGS. 3A and 3B  illustrate an apparatus for cleaning semiconductor wafer according to further another exemplary embodiment of the present invention. 
           [0014]      FIG. 4  illustrates an apparatus for cleaning semiconductor wafer according to further another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0015]    Referring to  FIG. 1A ,  FIG. 1A  illustrates an apparatus for cleaning semiconductor wafer according to an exemplary embodiment of the present invention. The apparatus includes a brush module  1018 , a swing arm  1010 , a rotating actuator  1011  and an elevating actuator  1012 . 
         [0016]    The brush module  1018  is mounted on an end of the swing arm  1010 . The brush module  1018  is vertically disposed and includes a brush head  1016 , a brush base  1015 , a lower bearing  1005 , a lower mounting section  1007 , a coil spring  1006 , an upper mounting section  1008 , an upper bearing  1020  and a damper  1009 . The brush head  1016  is mounted on the brush base  1015 . An end of the lower bearing  1005  connects to the brush base  1015  and the other end of the lower bearing  1005  connects to the lower mounting section  1007 . An end of the coil spring  1006  is fixed on the lower mounting section  1007  and the other end of the coil spring  1006  is fixed on the upper mounting section  1008  which is disposed opposite the lower mounting section  1007 . The upper mounting section  1008  connects to an end of the upper bearing  1020  and the other end of the upper bearing  1020  connects to the damper  1009 . The damper  1009 , which is liquid type or gas type, is used to keep the brush module  1018  stable at vertical direction during process. The brush head  1016  can be made of PVA sponge or nylon filament. 
         [0017]    The other end of the swing arm  1010  is connected with the rotating actuator  1011  and the elevating actuator  1012 . The rotating actuator  1011  drives the swing arm  1010  to swing across a whole wafer surface, so the brush head  1016  may move across the whole wafer surface during the cleaning process. The elevating actuator  1012  drives the swing arm  1010  to rise or descend, so the press force that the brush module  1018  acts on the wafer surface may be adjusted. The swing arm  1010  is able to swing, rise or descend, or swing and simultaneously rise or descend under the drive of the rotating actuator  1011  or/and the elevating actuator  1012 . A hard stopper  1014  is installed on the elevating actuator  1012  for restricting the vertical descend distance of the swing arm  1010  so as to restrict the press force of the brush head  1016  pressing on the wafer surface in an acceptable range. A strain gauge  1013  is positioned on the swing arm  1010  to monitor the deformation of the coil spring  1006  while the brush head  1016  pressing on the wafer surface. 
         [0018]    The apparatus further includes a cleaning chamber (not shown in  FIG. 1A ), the cleaning chamber includes a wafer chuck  1002 , a rotation driving mechanism  1004  and at least one nozzle  1019 . The wafer chuck  1002  is disposed in the cleaning chamber for holding and positioning a wafer  1001 . The rotation driving mechanism  1004  drives the wafer chuck  1002  to rotate. The at least one nozzle  1019  delivers cleaning chemicals or de-ionized water onto the surface of the wafer  1001 . 
         [0019]    When using the apparatus to cleaning the wafer  1001 , the wafer  1001  is loaded on the wafer chuck  1002 . The rotation driving mechanism  1004  drives the wafer chuck  1002  to rotate at a rotating speed. Preferably, the rotating speed is 30 RPM to 1500 RPM. The nozzle  1019  delivers cleaning chemicals or de-ionized water onto the surface of the wafer  1001  and the flow rate of the cleaning chemicals or de-ionized water is controlled in range of 100 ml/min to 4000 ml/min. The rotating actuator  1011  drives the swing arm  1010  to swing and make the brush module  1018  move into the cleaning chamber and the brush head  1016  is above the surface of the wafer  1001 . Then the elevating actuator  1012  drives the swing arm  1010  to descend and make the brush module  1018  descend to a position close to the surface of the wafer  1001  at a first speed. The swing arm  1010  continues to descend by the drive of the elevating actuator  1012  and make the brush module  1018  move down to a process position with a preset height at a second speed which is slower than the first speed. Both the first speed and the second speed are individually controllable. The rotating actuator  1011  drives the swing arm  1010  to swing and make the brush head  1016  of the brush module  1018  move across the surface of the wafer  1001  based on a pre-set recipe for cleaning the surface of the wafer  1001 . After the pre-set recipe is end of run, the swing arm  1010  stops swing and the elevating actuator  1012  drives the swing arm  1010  to rise so that the brush module  1018  is risen to a position above the surface of the wafer  1001 . The rotating actuator  1011  drives the swing arm  1010  to swing and move the brush module  1018  out of the cleaning chamber. The nozzle  1019  stops delivering cleaning chemicals or de-ionized water onto the surface of the wafer  1001 . At last, dry the wafer  1001  and unload the wafer  1001  from the wafer chuck  1002 . 
         [0020]    In the cleaning process described above, the brush module  1018  provides a mechanical force to the surface of the wafer  1001  and the strength of the mechanical force is controlled by driving the swing arm  1010  to rise or descend with the elevating actuator  1012 . The swing arm  1010  is driven by the rotating actuator  1011  to swing and make the brush head  1016  move across the whole surface of the wafer  1001  while the wafer  1001  rotates along with the wafer chuck  1002 . The swing arm  1010  is also driven by the elevating actuator  1012  to move down towards the wafer  1001  with a controllable vertical moving speed. The elevating actuator  1012  controls the swing arm  1010  and the brush module  1018  to a process position where the brush head  1016  presses on the surface of the wafer  1001 . The elastic deformation of the coil spring  1006 , which generates the press force that the brush head  1016  acts on the surface of the wafer  1001 , is determined by the height of the brush module  1018  process position. The nozzle  1019  delivers cleaning chemicals or de-ionized water to the surface of the wafer  1001 , while the brush head  1016  presses on the surface of the wafer  1001 . The cleaning chemicals or de-ionized water form a soft media between the brush head  1016  and the surface of the wafer  1001  so as to prevent scratch or damage on structures formed on the surface of the wafer  1001 . 
         [0021]    Referring to  FIG. 1B  illustrating an apparatus for cleaning semiconductor wafer according to another exemplary embodiment of the present invention, the apparatus adds a controller  1031  on the basis of the apparatus illustrated in  FIG. 1A . The controller  1031  respectively connects with the strain gauge  1013  and the elevating actuator  1012 . The strain gauge  1013 , the controller  1031  and the elevating actuator  1012  form a close loop control for controlling a vertical process position of the swing arm  1010  in real time while the swing arm  1010  scanning across the surface of the wafer  1001  during the cleaning process, so a vertical process position of the brush module  1018  may be controlled in real time. The press force of the brush module  1018  acted onto the surface of the wafer  1001  is detected by the strain gauge  1013  and the strain gauge  1013  produces a detecting signal. The strain gauge  1013  sends the detecting signal to the controller  1031 . The controller  1031  receives the detecting signal and gives a feedback to the elevating actuator  1012 . The elevating actuator  1012  adjusts the height of the process position of the swing arm  1010  based on the feedback of the controller  1031 . 
         [0022]    Referring to  FIGS. 2A and 2B  illustrating an apparatus for cleaning semiconductor wafer according to another exemplary embodiment of the present invention, the apparatus includes a brush module  2018 , a swing arm  2010 , a rotating actuator  2011  and an elevating actuator  2012 . 
         [0023]    The brush module  2018  is mounted on an end of the swing arm  2010 . The brush module  2018  is vertically disposed and includes a brush head  2016 , a brush base  2015 , a lower bearing  2005 , a lower mounting section  2007 , a coil spring  2006 , an upper mounting section  2008 , an upper bearing  2020  and a damper  2009 . The brush head  2016  is mounted on the brush base  2015 . An end of the lower bearing  2005  connects to the brush base  2015  and the other end of the lower bearing  2005  connects to the lower mounting section  2007 . An end of the coil spring  2006  is fixed on the lower mounting section  2007  and the other end of the coil spring  2006  is fixed on the upper mounting section  2008  which is disposed opposite the lower mounting section  2007 . The upper mounting section  2008  connects to an end of the upper bearing  2020  and the other end of the upper bearing  2020  connects to the damper  2009 . The damper  2009 , which is liquid type or gas type, is used to keep the brush module  2018  stable at vertical direction during process. 
         [0024]    The other end of the swing arm  2010  is connected with the rotating actuator  2011  and the elevating actuator  2012 . The rotating actuator  2011  drives the swing arm  2010  to swing across a whole wafer surface, so the brush module  2018  may move across the whole wafer surface during the cleaning process. The elevating actuator  2012  drives the swing arm  2010  to rise or descend, so the press force that the brush module  2018  acts on the wafer surface can be adjusted. The swing arm  2010  is able to swing, rise or descend, or swing and simultaneously rise or descend under the drive of the rotating actuator  2011  or/and the elevating actuator  2012 . A hard stopper  2014  is installed on the elevating actuator  2012  for restricting the vertical descend distance of the swing arm  2010  so as to restrict the press force of the brush head  2016  pressing on the wafer surface in an acceptable range. A strain gauge  2013  is positioned on the swing arm  2010  to monitor the deformation of the coil spring  2006  while the brush head  2016  pressing on the wafer surface. 
         [0025]    The apparatus further includes a cleaning chamber  2000 . The cleaning chamber  2000  includes a water chuck, a rotation driving mechanism and at least one nozzle. The wafer chuck is disposed in the cleaning chamber  2000  for holding and positioning a wafer  2001 . The rotation driving mechanism drives the wafer chuck to rotate. The at least one nozzle  2019  delivers cleaning chemicals or de-ionized water onto the surface of the wafer  2001 . 
         [0026]    A brush cleaning port  2040  is arranged beside the cleaning chamber  2000  and used for cleaning the brush head  2016  when the brush head  2016  is idle and checking whether the brush module  2018  is in normal status. The brush cleaning port  2040  includes at least one outlet  2043  and at least one inlet  2041 . A force sensor  2045  is installed at the bottom of the brush cleaning port  2040  and is connected with a controller through a signal cable  2047 . A cover  2049  shields the force sensor  2045  for protecting the force sensor  2045  from contacting cleaning liquid in the brush cleaning port  2040 . When the brush head  2016  is idle, the rotating actuator  2011  drives the swing arm  2010  to move out of the cleaning chamber  2000  and move into the brush cleaning port  2040 . The elevating actuator  2012  drives the brush head  2016  to move down to the brush cleaning port  2040  with a preset height of the cleaning position. The cleaning liquid, such as de-ionized water, sprays to the brush head  2016 . A gap is set between the brush head  2016  and the force sensor  2045 . If the brush module  2018  is abnormal, such as the coil spring  2006  working abnormally, the force sensor  2045  detects the press force and sends out a signal to prevent the apparatus from processing the wafer  2001 . 
         [0027]    Referring to  FIGS. 3A and 3B  illustrating an apparatus for cleaning semiconductor wafer according to further another exemplary embodiment of the present invention, the apparatus includes a brush module  3018 , a swing arm  3010 , a rotating actuator  3011  and an elevating actuator  3012 . 
         [0028]    The brush module  3018  is mounted on an end of the swing arm  3010 . The brush module  3018  is vertically disposed and includes a brush head  3016 , a brush base  3015 , a lower bearing  3005 , a lower mounting section  3007 , a coil spring  3006 , an upper mounting section  3008 , an upper bearing  3020  and a damper  3009 . The brush head  3016  is mounted on the brush base  3015 . An end of the lower bearing  3005  connects to the brush base  3015  and the other end of the lower bearing  3005  connects to the lower mounting section  3007 . An end of the coil spring  3006  is fixed on the lower mounting section  3007  and the other end of the coil spring  3006  is fixed on the upper mounting section  3008  which is disposed opposite the lower mounting section  3007 . The upper mounting section  3008  connects to an end of the upper bearing  3020  and the other end of the upper bearing  3020  connects to the damper  3009 . The damper  3009 , which is liquid type or gas type, is used to keep the brush module  3018  stable at vertical direction during process. 
         [0029]    The other end of the swing arm  3010  is connected with the rotating actuator  3011  and the elevating actuator  3012 . The rotating actuator  3011  drives the swing arm  3010  to swing across a whole wafer surface, so the brush module  3018  may move across the whole wafer surface during the cleaning process. The elevating actuator  3012  drives the swing arm  3010  to rise or descend, so the press force that the brush module  3018  acts on the wafer surface can be adjusted. The swing arm  3010  is able to swing, rise or descend, or swing and simultaneously rise or descend under the drive of the rotating actuator  3011  or/and the elevating actuator  3012 . A hard stopper  3014  is installed on the elevating actuator  3012  for restricting the vertical descend distance of the swing arm  3010  so as to restrict the press force of the brush head  3016  pressing on the wafer surface in an acceptable range. A strain gauge  3013  is positioned on the swing arm  3010  to monitor the deformation of the coil spring  3006  while the brush head  3016  pressing on the wafer surface. 
         [0030]    The apparatus further includes a cleaning chamber  3000 . The cleaning chamber  3000  includes a wafer chuck, a rotation driving mechanism and at least one nozzle  3019 . The wafer chuck is disposed in the cleaning chamber  3000  for holding and positioning a wafer  3001 . The rotation driving mechanism drives the wafer chuck to rotate. The at least one nozzle  3019  for delivers cleaning chemicals or de-ionized water onto the surface of the wafer  3001 . 
         [0031]    A brush cleaning port  3040  is arranged beside the cleaning chamber  3000  and used for cleaning the brush head  3016  when the brush head  3016  is idle and checking whether the brush module  3018  is in normal status. The brush cleaning port  3040  includes at least one outlet  3043  and at least one inlet  3041 . A force sensor  3045  is installed at the bottom of the brush cleaning port  3040  and is connected with a controller through a signal cable  3047 . A cover  3049  shields the force sensor  3045  for protecting the force sensor  3045  from contacting cleaning liquid in the brush cleaning port  3040 . A couple of brush position sensors  3051  are settled at opposite sides of the brush cleaning port  3040  for checking the status of the brush module  3018 . The brush position sensors  3051  will be triggered when the brush head  3016  moves down in the brush cleaning port  3040 . The vertical moving distance of the brush head  3016  at the time that the brush position sensors  3051  are triggered is recorded, and is compared each time. If the value of vertical moving distance is out of the preset range, a signal of the brush module  3018  abnormal is sent out. 
         [0032]    Referring to  FIG. 4  illustrating an apparatus for cleaning semiconductor wafer according to further another exemplary embodiment of the present invention, the apparatus includes a brush module  4018 , a swing arm  4010 , a rotating actuator  4011  and an elevating actuator  4012 . 
         [0033]    The brush module  4018  is mounted on an end of the swing arm  4010 . The brush module  4018  is vertically disposed and includes a brush head  4016 , a brush base  4015 , a bearing  4005 , a flexible component  4007 , at least one damper  4009 , a coil spring  4006 , a mounting section  4008  and a brush shell  4020 . The brush head  4016  is mounted on the brush base  4015 . An end of the bearing  4005  connects with the brush base  4015  and the other end of the bearing  4005  penetrates into the brush shell  4020  and connects to a side of the flexible component  4007 . The other side of the flexible component  4007  connects with the damper  4009  which is mounted on the brush shell  4020  and used for keeping the brush module  4018  stable at vertical direction during process. The coil spring  4006  is received in the brush shell  4020 . An end of the coil spring  4006  is fixed on the side of the flexible component  4007  and the other end of the coil spring  4006  is fixed on the mounting section  4008  which is disposed at the top of the brush shell  4020  and opposite to the flexible component  4007 . The mounting section  4008  can be the top plate of the brush shell  4020 . The brush shell  4020  is fixed at the end of the swing arm  4010  for mounting the brush module  4018  on the end of the swing arm  4010 . 
         [0034]    The other end of the swing arm  4010  is connected with the rotating actuator  4011  and the elevating actuator  4012 . The rotating actuator  4011  drives the swing arm  4010  to swing across a whole wafer surface, so the brush module  4018  may move across the whole wafer surface during the cleaning process. The elevating actuator  4012  drives the swing arm  4010  to rise or descend, so the press force that the brush module  4018  acts on the wafer surface can be adjusted. The swing arm  4010  is able to swing, rise or descend, or swing and simultaneously rise or descend under the drive of the rotating actuator  4011  or/and the elevating actuator  4012 . A hard stopper  4014  is installed on the elevating actuator  4012  for restricting the vertical descend distance of the swing arm  4010  so as to restrict the press force of the brush head  4016  pressing on the wafer surface in an acceptable range. A strain gauge  4013  is positioned on the swing arm  4010  to monitor the deformation of the coil spring  4006  while the brush head  4016  pressing on the wafer surface. 
         [0035]    The apparatus further includes a cleaning chamber. The cleaning chamber includes a wafer chuck  4002 , a rotation driving mechanism  4004  and at least one nozzle  4019 . The wafer chuck  4002  is disposed in the cleaning chamber for holding and positioning a wafer  4001  The rotation driving mechanism  4004  drives the wafer chuck  4002  to rotate. The at least one nozzle  4019  delivers cleaning chemicals or de-ionized water onto the surface of the wafer  4001 . 
         [0036]    A method for cleaning semiconductor wafer according to the present invention is also disclosed. 
         [0037]    Step 1: loading a wafer on a wafer chuck and rotating the wafer with a speed of 30 RPM to 1500 RPM. 
         [0038]    Step 2: delivering cleaning chemicals or de-ionized water onto the surface of the wafer, wherein the flow rate of the cleaning chemicals or de-ionized water is controlled in range of 100 ml/min to 4000 ml/min. 
         [0039]    Step 3: moving a brush module into a cleaning chamber and a brush head of the brush module being above the surface of the wafer. 
         [0040]    Step 4: moving the brush module down to a position close to the surface of the wafer at a first speed which is controllable. 
         [0041]    Step 5: moving the brush module down to a process position with a preset height at a second speed which is controllable and slower than the first speed. 
         [0042]    Step 6: swinging the brush head of the brush module across the surface of the wafer based on a pre-set recipe. 
         [0043]    Step 7: moving the brush module up to a position above the wafer. 
         [0044]    Step 8: swinging the brush module out of the cleaning chamber, and preferably swinging the brush module to a brush cleaning port to clean the brush head. 
         [0045]    Step 9: stopping delivering cleaning chemicals or de-ionized water to the surface of the wafer. 
         [0046]    Step 10: drying the wafer. 
         [0047]    Step 11: unloading the wafer from the wafer chuck. 
         [0048]    In the step 5, the brush module&#39;s height of the process position is pre-calibrated according to the press force that the brush head acted on the surface of the wafer. 
         [0049]    In the step 8, the brush head cleaning process includes moving the brush head down into the brush cleaning port where the cleaning liquid is sprayed to the brush head. And in the normal case, the brush head is kept a distance from a force sensor mounted inside the brush cleaning port. The force sensor detects the force when the brush module is abnormal, such as a coil spring of the brush module being abnormal, alarm occurs in the system and the wafer is stopped to feed in. 
         [0050]    The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. Such modifications and variations that may be apparent to those skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.