Abstract:
A semiconductor structure includes a molding compound, a conductive plug, and a cover. The conductive plug is in the molding compound. The cover is over a top meeting joint between the conductive plug and the molding compound. The semiconductor structure further has a dielectric. The dielectric is on the cover and the molding compound.

Description:
FIELD 
       [0001]    The disclosure relates to an apparatus and a method for cleaning a plate, and more particularly to a cleaning system for cleaning a plate designed for cleaning a wafer surface. 
       BACKGROUND 
       [0002]    Wafer level packaging (WLP) technology combines dies having different functionalities at a wafer level, and is widely applied in order to meet continuous demands toward the miniaturization and higher functions of electronic components. The WLP technology includes few operations, such as bonding two different wafers into an integral part (called wafer bonding hereinafter) and then proceeding to a sigulation process to cut the integral part into a singulated package. 
         [0003]    Fusion bonds and hybrid bonds are two terms generally used to categorize various wafer bonding methods. A fusion bond refers to a wafer bonding method in which there is only dielectric material involved on the bonding surface. The hybrid bond, on the other hand, refers a wafer bonding method in which has a dielectric and a metallic material contained on the bonding surface. The hybrid bond is more complicated than the fusion bond because it includes two different materials. In some examples such as CMOS image sensor (CIS) wafer bonding, a bonded interface includes copper and silicon oxide. 
         [0004]    The wafer bonding is based on chemical bonds between two surfaces of any materials that meet numerous requirements specified for the wafer surface. As such, the wafer surface must be clean. Otherwise, unbonded areas called voids, i.e. interface bubbles, can occur. However, during a wafer bonding process, cleanness of a wafer surface is a challenge and affected by some factors, such as cross contamination or clean tool deviation. Thus, a system or a method to provide a clean wafer surface is still in great demand. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
           [0006]    A more complete understanding of the present disclosure may be derived by referring to the detailed description and claims when considered in connection with the Figures, where like reference numbers refer to similar elements throughout the Figures, and: 
           [0007]      FIG. 1  is a schematic view of a semiconductor wafer cleaning system for cleaning a plate designed for cleaning a wafer surface. 
           [0008]      FIG. 2  is a schematic view of a plate and an arm connecting with the plate, which moves along X, Y, or Z direction. 
           [0009]      FIG. 3  is a cross-sectional view of a plate, which includes two layers. The top layer is designed to guide the liquid toward the bottom layer. 
           [0010]      FIG. 4  is a cross-sectional view of a top layer, which include two opening. One is designed to guide liquid into the plate while the other is configured to drain the liquid from the second layer out the plate. 
           [0011]      FIG. 5  is a cross-sectional view of a porous structure of the second layer, which vibrates the liquid inside the porous structure to generate ultrasonic waves. 
           [0012]      FIG. 6  is a schematic view of a portion of a semiconductor wafer cleaning system where the relationship between the sonicator and the plate is described. 
           [0013]      FIG. 7  is a schematic view of a portion of a semiconductor wafer cleaning system where the relationship between the wave sensor and the wave reflector is illustrated. 
           [0014]      FIG. 8  is a schematic view of a portion of a semiconductor wafer cleaning system where the position of the particle removal component is described. 
           [0015]      FIG. 9  is a schematic view of a portion of a semiconductor wafer cleaning system where the relationship between the cleaning bar and the plate is illustrated. 
           [0016]      FIG. 10  is a schematic view of a portion of a semiconductor wafer cleaning system where the relationship between the nozzle and the plate is described. 
           [0017]      FIG. 11  is a schematic view of a semiconductor wafer cleaning system for cleaning a plate in different modes. 
           [0018]      FIG. 12  is a schematic view of a portion of a semiconductor wafer cleaning system where an IPA tank and the location thereof are described. 
           [0019]      FIG. 13  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the relationship between the sonicator and the exit is illustrated. 
           [0020]      FIG. 14  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the coupling relationship among the sonicator, the plate and the container is described. 
           [0021]      FIG. 15  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the relationship between the inlet and the exit is described. 
           [0022]      FIG. 16  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the brush is illustrated. 
           [0023]      FIG. 17  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the relationship between the heating element and the plate is described. 
           [0024]      FIG. 18  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the relationship between a funneled container and the exit is illustrated. 
           [0025]      FIG. 19  is a schematic view of an apparatus of a semiconductor wafer cleaning system where a container including two walls with different heights is described. 
           [0026]      FIG. 20  is a schematic view of an apparatus of a semiconductor wafer cleaning system where the relationship between the nozzle and the plate in the container with two walls is illustrated. 
           [0027]      FIG. 21  is a diagram of a method for cleaning a plate designed for cleaning a wafer surface. 
           [0028]      FIG. 22  is a schematic view of a semiconductor wafer cleaning system for cleaning a plate designed for several modes corresponding to different positions. 
           [0029]      FIG. 23  is a schematic view of an operation of moving the plate to a container. 
           [0030]      FIG. 24  is a schematic view of an operation of immersing the plate into a liquid. 
           [0031]      FIG. 25  is a schematic view of an operation of applying a power of an ultrasonic wave on the plate. 
           [0032]      FIG. 26  is a schematic view of an operation of dehydrating the plate. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are generally used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of the claimed subject matter. It is evident, however, that the claimed subject matter can be practiced without these specific details. In other instances, structures and devices are illustrated in block diagram form in order to facilitate describing the claimed subject matter. 
         [0034]    In the present disclosure, an apparatus is designed to clean a plate that is used to clean a surface of a wafer. The plate is constantly cleaned with the apparatus in order to keep the plate in an optimized condition, such as without any particle or other contamination sources attached. 
         [0035]    In various embodiments, the plate and the apparatus are in a system and the system is used to clean a surface of a wafer before the wafer is bonded to another wafer. In some embodiments, the plate in system is designed to clean a batch of wafers continuously and the apparatus built in the system is designed to clean the plate with a predetermined interval. Thus, the plate does not cause the cross contamination on the wafers. 
         [0036]      FIG. 1  is a semiconductor wafer cleaning system  200  designed to clean a top surface  1  of a semiconductor wafer  2 . In various embodiments, the semiconductor wafer  2  includes CIS devices and the top surface  1  includes oxide and metal. In some embodiments, the metal includes copper. The semiconductor wafer  2  is directly bonded with another wafer after cleaned by the semiconductor wafer cleaning system  200 . In some embodiments, the semiconductor wafer cleaning system  200  is connected with a loader  3  and the loader  3  is designed to send wafers continuously into the semiconductor wafer cleaning system  200 . In some embodiments as in  FIG. 1 , the semiconductor wafer cleaning system  200  has several chambers, such as  4  and  5  and the semiconductor wafer  2  travels through the chambers  4  and  5  to receive a complete clean operation. A first chamber  4  is a wafer clean station in which the top surface  1  of the semiconductor wafer  2  is cleaned when the semiconductor wafer  2  is located inside the first chamber  4 . In addition, semiconductor wafer cleaning system  200  includes a cup  6 , a clean unit  50 , a plate  22  and an arm  21  connecting to the plate  22  in the first chamber  4 . A wafer chuck  7  is inside the cup  6  and a container  51  is disposed inside the clean unit  50 . 
         [0037]    The first chamber  4  includes the cup  6  designed for accommodating the semiconductor wafer  2  and draining a clean liquid, which is used to clean the semiconductor wafer  2 . The wafer chuck  7  is designed for holding the semiconductor wafer  2  on the wafer chuck  7  for further spinning motion. In some embodiments, the wafer chuck  7  applies vacuum to the bottom surface of the semiconductor wafer  2  so as to hold the semiconductor wafer  2  on the wafer chuck  7  in a rotation (from about 500 to about 5000 rpm). In addition, the second chamber  5  is designed for other wafer processes, such as drying wafer bonding and so on. 
         [0038]    The plate  22  is used to clean the top surface  1  of the semiconductor wafer  2 . In some embodiments, the semiconductor wafer cleaning system  200  is designed to be able to operate under a first mode and a second mode. Under the first mode, the plate  22  is at a first position  8 . Under the second mode, the plate  22  is at a second position  9 . In some embodiments, the first mode is a run mode, which indicates that the semiconductor wafer  2  is in the first chamber  4  and cleaned by the plate  22 . The second mode is a self-clean mode, which indicates that the plate  22  is cleaned in a clean unit  50 . 
         [0039]    The arm  21  designed to control the position of the plate  22 , which is pivoted to an arm  21 . In some embodiments, the arm  21  conducts a three-dimensional motion.  FIG. 2  is an enlarged view of the arm  21  and the plate  22 . The arm  21  moves the plate  22  along X, Y, or Z direction. In some embodiments, the plate  22  is swiveled by the arm  21 , for example the plate  22  is moved from the first position  8  to the second position  9  as previously discussed with reference to  FIG. 1 . 
         [0040]    In some embodiments as in  FIG. 2 , the plate  22  is in a pie shape that is designed for cleaning a great amount of the wafer surface per timeframe. However, in certain embodiments, the plate  22  is in, but not limited to, a triangular shape, a square shape, a quadrilateral shape, or a polygonal shape. Other shapes are within the contemplated scope of the present disclosure. 
         [0041]      FIG. 3  is a cross-sectional view of a plate  22 . The plate  22  includes a first layer  221  and a second layer  222 . The first layer  221  includes several holes  223  as liquid inlets. In some embodiments, the holes  223  are connected with tubes for introducing clean liquid into the plate  22 . The second layer  222  includes several through holes  224  guiding the clean liquid from the hole  223  to the top surface  1  of the semiconductor wafer  2  as previously discussed with reference to  FIG. 1 . 
         [0042]    In some embodiments, the first layer  221  is made of a material selected from polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene, polymethylmethacrylate, poly lactic acid, polycarbonates and fiber reinforced plastic. In some embodiments, the second layer  222  is made of a piezoelectric material selected from ceramic, sapphire, tourmaline crystal, quartz crystal, topaz crystal, sodium potassium tartrate tetrahydrate crystal and polyvinylidene fluoride, Sodium potassium niobate ((K,Na)NbO 3 ), Bismuth ferrite (BiFeO 3 ), Sodium niobate (NaNbO 3 ), Bismuth titanate (Bi 4 Ti 3 O 12 ), Sodium bismuth titanate (Na 0.5 Bi 0.5 TiO 3 ), Gallium orthophosphate crystal (GaPO 4 ), Langasite crystal (La 3 Ga 5 SiO 14 ), Barium titanate (BaTiO 3 ), Lead titanate (PbTiO 3 ), Lead zirconate titanate (Pb[Zr x Ti 1-x ]O 3  0≦x≦1), Potassium niobate (KNbO 3 ), Lithium niobate (LiNbO 3 ), Lithium tantalite (LiTaO 3 ), Sodium tungstate (Na 2 WO 3 ) and Zinc oxide (ZnO). 
         [0043]    In some embodiments as in  FIG. 4 , the first layer  221  includes a first hole  225  and a second hole  226 . The first hole  225  is designed for the clean liquid to flow in and the second hole  226  is configured to drain the clean liquid out so as to clean a top surface of a semiconductor wafer. 
         [0044]    In some embodiments as in  FIG. 5 , the second layer  222  includes several pores  227 . In certain embodiments, some of the pores  227  are connected with each other. The pores  227  are channels to guide the clean liquid from holes  223  to a top surface of a semiconductor wafer. In certain embodiments, the pores  227  are designed to form inside the plate  22  or on a surface of the second layer  222 . 
         [0045]    In some embodiments, the plate  22  includes the second layer  222  without the first layer  211  disposed thereon. In some embodiments, a pipe is configured to directly guide the clean liquid to the through holes  224  or to the pores  227  as previously discussed with references to  FIGS. 3 to 5 . 
         [0046]      FIG. 6  is a portion of a semiconductor wafer cleaning system  200   a  according to some embodiments of the present disclosure. A sonicator  30  is coupled to the plate  22  as previously discussed and the plate  22  is located in the container  51  of the clean unit  50 . A wire  31  is designed to transfer a signal S between the sonicator  30  and a second layer  222  of the plate  22 . The semiconductor wafer cleaning system  200   a  includes a wave sensor  24  coupled to the plate  22 . An electric wire  25  is designed to transfer a reflected signal between the wave sensor  24  and the second layer  222  of the plate  22 . The arm  21  is connected to the plate  22 . 
         [0047]    The sonicator  30  is designed to generate the signal S toward the plate  22 . In some embodiments, the signal S has a frequency from about 20 KHz to about 40 KHz. In some other embodiments, the frequency is from about 25 KHz to about 60 KHz. In still other embodiments, the frequency is from about 28 KHz to about 80 KHz. In various embodiments, the second layer  222  is activated by the signal S so as to sonicate a liquid in the second layer  222 . The previously discussed frequency is used to properly sonicate the liquid. In some embodiments, the sonicator  30  is inside the second layer  222  such that the sonicator  30  transfers the signal S without the wire  31 . In some embodiments, the sonicator  30  is inside the arm  21  and the sonicator  30  is controlled correspondingly to the position of the plate  22 . Once the arm  21  is located at a prearranged position, the sonicator  30  transfers the signal S to the plate  22 . In some other embodiments, the signal S from the sonicator  30  is wirelessly transferred to the plate  22 . 
         [0048]    The signal S has a power for generating an ultrasonic wave. In some embodiments, the power of the ultrasonic wave generated by the sonicator  30  is adjustable. In some embodiments, the power is in a range from about 19 to about 35 W. In some other embodiments, the power is in a range from about 15 to about 23 W. In some other embodiments, the power is in a range from about 18 to about 33 W. In certain embodiments, the power is manually adjusted to the previously discussed ranges to avoid cross contamination. In some other embodiments, the power is automatically adjusted to the previously discussed ranges to prevent the power of the signal S from over 35 W. Once the power is over 35 W, the cross contamination effect occurs frequently. 
         [0049]    The wire  31  is electrically connected between the sonicator  30  and the plate  22 . In certain embodiments, the wire  31  is inside the arm  21  to prevent the wire  31  from contacting the liquid. In certain embodiments, the wire  31  is connected with the first layer  221  in order to be coupled with the second layer  222  so as to transfer the signal S to the second layer  222 . 
         [0050]    The plate  22  is used to generate the ultrasonic wave. Because the second layer  222  of the plate  22  includes a piezoelectric material, the signal S used to agitate the second layer  222  so as to generate the ultrasonic wave. In some embodiments, the first layer  221  includes a piezoelectric material, which is agitated by the signal S to generate the ultrasonic wave. 
         [0051]    In some embodiments, the plate  22  is used to receive a reflected ultrasonic wave from a bottom surface  55  of the clean unit  50 . The second layer  222  of the plate  22  converts the reflected ultrasonic wave to a reflected signal R and transfers the reflected signal R to the wave sensor  24 . In other words, the piezoelectric material of the second layer  222  of the plate  22  converts the reflected ultrasonic wave from the bottom surface  55  of the container  51  to the reflected signal R. In certain embodiments, the piezoelectric material of the first layer  221  converts the reflected ultrasonic wave to the reflected signal R, which is transferred to the wave sensor  24 . 
         [0052]    The electric wire  25  is electrically connected between the plate  22  and the wave sensor  24 . In some embodiments, the electric wire  25  is inside the arm  21  to prevent the electric wire  25  from contacting the liquid. In certain embodiments, the electric wire  25  is connected with the first layer  221  in order to be coupled with the second layer  222  so as to transfer the reflected signal R to the wave sensor  24 . 
         [0053]    In various embodiments, the wave sensor  24  is used to calibrate the power of the ultrasonic wave generated by the sonicator  30 . In some embodiments, the wave sensor  24  calculates a reflected power corresponding to the reflected signal R. The reflected power calculated is used to check up the power of the ultrasonic wave generated by the sonicator  30 . In some embodiments, the wave sensor  24  transfers the reflected signal R to a processor. The processor calculates the reflected power corresponding to the reflected signal R. The reflected power calculated is used to check up the power of the ultrasonic wave generated by the sonicator  30 . 
         [0054]    In certain embodiments, the wave sensor  24  is disposed on the plate  22 . In some embodiments, the wave sensor  24  is inside the second layer  222 . In some other embodiments, the wave sensor  24  is inside the arm  21  to prevent the wave sensor  24  from contacting the liquid. 
         [0055]    In some embodiments, the wave sensor  24  transfers an adjusting signal to the sonicator  30 . The power of the ultrasonic wave generated by the sonicator  30  is adjusted in accordance with the adjusting signal so as to fall into the previously discussed ranges. In certain embodiments, the second layer  222  of the plate  22  includes a wireless transmitter, which transfers the reflected signal R to the wave sensor  24 . Additionally, the wave sensor  24  includes a wireless module that transfers the adjusting signal to the sonicator  30 . In some other embodiments, the wave sensor  24  is used to judge whether the power of the ultrasonic wave falls within the power range as previously discussed. If not, the sonicator  30  is adjusted until the power of the ultrasonic wave falls within the range. Thus, the wave sensor  24  is designed to prevent the power of the ultrasonic wave from exceeding 35 W so as to avoid the cross contamination. 
         [0056]    In  FIG. 6 , the clean unit  50  of the semiconductor wafer cleaning system  200   a  is configured to receive the plate  22  during the second mode. The clean unit  50  includes the container  51  used for accommodating the liquid. Moreover, the container  51  includes an opening  52  which allows the arm  21  to pivot the plate  22  through the opening  52 . In some embodiments, the opening  52  is used for the liquid to pour into the container  51 . 
         [0057]    In some embodiments as referred in  FIG. 7 , the plate  22 , the arm  21 , the wave sensor  24 , the sonicator  30 , the wire  31 , and the electric wire  25  are previously discussed with reference to  FIG. 6 . The clean unit  50  includes a wave reflector  54  that is disposed on the bottom surface  55  of the container  51 . That is, the wave reflector  54  is disposed under the plate  22  and designed to reflect the ultrasonic wave from the second layer  222  of the plate  22  during the second mode for adjusting the power of the ultrasonic wave. 
         [0058]    In other embodiments, the wave reflector  54  is disposed between the plate  22  and the container  51 . In other words, the wave reflector  54  is disposed above the bottom surface  55  of the container  51   
         [0059]    In order for the precise adjustment of the ultrasonic power, the gap D between the wave reflector  54  and a surface  228  of the plate  22  is a predetermined distance. In some embodiments, the predetermined gap D is between about 1 mm and about 4 mm. In certain embodiments, the predetermined gap D is between about 0.5 mm and about 2.8 mm. In other embodiments, the predetermined gap D is between about 1.7 mm and about 3.1 mm. In some other embodiments, the predetermined gap D is between about 1.3 mm and about 4.6 mm. The previous gap distance is designed to eliminate the deviation of the power of the ultrasonic wave to avoid cross contamination. 
         [0060]      FIG. 8  is a portion of a semiconductor wafer cleaning system  200   b  according to some embodiments of the present disclosure. The plate  22  and the arm  21  are previously discussed with reference to  FIG. 6 . The semiconductor wafer cleaning system  200   b  includes a particle removal component  10  designed for cleaning the plate  22 . For instance, the particle removal component  10  utilizes, but not limited to, a stream of flow to detach the particles trapped inside the second layer  222  of the plate  22 . 
         [0061]    In some embodiments as referred in  FIG. 8 , the particle removal component  10  includes an exit  11 . The exit  11  is disposed at a wall  56  of the container  51  and designed to drain the liquid out so as to form a stream of flow. The stream of flow detaches the particle and carries the particle out of the container  51 . Thus, the plate  22  is cleaned by the particle removal component  10 . 
         [0062]      FIG. 9  is a portion of a semiconductor wafer cleaning system  200   c  according to some embodiments of the present disclosure. The particle removal component  10  includes a moving arm  12  and a cleaning bar  13 , which is pivoted to the moving arm  12 . The cleaning bar  13  includes several protrusions  131  that are used to scrub the plate  22 . Mechanical cleaning force is applied to the plate  22  and the particles are removed from the plate  22 . 
         [0063]      FIG. 10  is a portion of a semiconductor wafer cleaning system  200   d  according to some embodiments of the present disclosure. The plate  22 , the arm  21 , and the container  51  are previously discussed with reference to  FIG. 6 . The particle removal component  10  includes a tube  14  and a nozzle  15 , which is connected to the tube  14 . The tube  14  is designed to guide the liquid to the nozzle  15  and the nozzle  15  is used to eject the liquid to the plate  22  for cleaning. 
         [0064]      FIG. 11  is a semiconductor wafer cleaning system  200   e  according to some embodiments of the present disclosure. The top surface  1 , the semiconductor wafer  2 , the loader  3 , the chambers  4  and  5 , the cup  6 , the wafer chuck  7 , the clean unit  50 , the container  51 , the arm  21  and the plate  22  are previously discussed with reference to  FIG. 1 . The semiconductor wafer cleaning system  200   e  further includes an IPA tank  57 . The semiconductor wafer cleaning system  200   e  is designed to be able to operate under a third mode. Under the third mode, the plate  22  is located at a position  58 . In some embodiments, the third mode is a dry mode, which indicates that the plate  22  is dried in the IPA tank  57 . 
         [0065]      FIG. 12  is an enlarged view of the IPA tank  57  designed for dehydrating the plate  22 . The IPA tank  57  is used to accommodate the non-polar solvent for dehydrating the plate  22 . In certain embodiments, the IPA tank  57  is replaced by a heating element, which dries the plate  22  during the third mode. Thus, the plate  22  is heated by the heating element. 
         [0066]      FIG. 13  is an apparatus  70  used for cleaning a plate  22  designed for cleaning a wafer surface. The apparatus  70  includes a container  51 , an exit  11  and a sonicator  30  as previously discussed. However, the sonicator  30  is coupled to the container  51  for generating an ultrasonic wave. 
         [0067]    In some embodiments, the container  51  has an opening  52  and a bottom surface  55 . The opening  52  is configured to receive the plate  22 . In addition, the container  51  is made of a piezoelectric material selected from ceramic, sapphire, tourmaline crystal, quartz crystal, topaz crystal, sodium potassium tartrate tetrahydrate crystal and polyvinylidene fluoride, Sodium potassium niobate ((K,Na)NbO 3 ), Bismuth ferrite (BiFeO 3 ), Sodium niobate (NaNbO 3 ), Bismuth titanate (Bi 4 Ti 3 O 12 ), Sodium bismuth titanate (Na 0.5 Bi 0.5 TiO 3 ), Gallium orthophosphate crystal (GaPO 4 ), Langasite crystal (La 3 Ga 5 SiO 14 ), Barium titanate (BaTiO 3 ), Lead titanate (PbTiO 3 ), Lead zirconate titanate (Pb[Zr x Ti 1-x ]O 3  0≦x≦1), Potassium niobate (KNbO 3 ), Lithium niobate (LiNbO 3 ), Lithium tantalite (LiTaO 3 ), Sodium tungstate (Na 2 WO 3 ) and Zinc oxide (ZnO). 
         [0068]    In some embodiments, the exit  11  is located at the wall  56  of the container  51 . However, in certain embodiments, the exit  11  is disposed at the bottom surface  55  of the container  51 . 
         [0069]    In some embodiments, the sonicator  30  coupled to the container  51  generates a signal U toward the container  51 . In some embodiments, the signal has a frequency from about 19 KHz to about 39 KHz. In other embodiments, the frequency is from about 26 KHz to about 61 KHz. In still other embodiments, the frequency is from about 29 KHz to about 79 KHz. The previously discussed frequency is used to properly agitate the liquid. In certain embodiments, the container  51  is agitated by the signal U so as to sonicate the liquid in the container  51  and to generate an ultrasonic wave. 
         [0070]    In some embodiments, the power of the ultrasonic wave from the sonicator  30  is adjustable. In some embodiments, the ultrasonic power is adjustable in a range from about 18 to about 35 W. In other embodiments, the power is in a range from about 14 to about 22 W. In some other embodiment, the power is in a range from about 17 to about 34 W. 
         [0071]      FIG. 14  is an apparatus  70   a  according to some embodiments of the present disclosure. The sonicator  30  is coupled to the plate  22  and the container  51 . In addition, the container  51  includes the wave reflector  54  which is protruded from the bottom surface  55  of the container  51 . The wave reflector  54  is disposed parallel to the second layer  222  of the plate  22  for a complete wave reflection without deviation. Furthermore, because the sonicator  30  is coupled to the plate  22  and the container  51 , the plate  22  and the container  51  are simultaneously agitated and oscillate with greater amplitude at some frequencies so as to form the ultrasonic wave. The frequency is from about 29 KHz to about 35 KHz. In some other embodiments, the frequency is from about 31 KHz to about 58 KHz. In still other embodiments, the frequency is from about 37 KHz to about 67 KHz. In addition, the exit  11  is used to form the stream of flow, which is able to carry the particles, detached by the ultrasonic wave, out of the container  51 . 
         [0072]      FIG. 15  is an apparatus  70   b  according to some embodiments of the present disclosure. The apparatus  70   b  further includes an inlet  59 , which is disposed on a first side  53  of the container  51 . The first side  53  is disposed corresponding to the wall  56 . In other words, the inlet  59  is disposed relative to the exit  11 . The inlet  59  and the exit  11  are designed to form a stream of flow. The inlet  59  and the exit  11  to form a turbulence of flow toward the plate  22  for cleaning the plate  22 . 
         [0073]      FIG. 16  is an apparatus  70   c  according to some embodiments of the present disclosure. The apparatus  70   c  includes a particle removal component  10 . The particle removal component  10  has a brush  16  including a brush arm  161  and a brush head  162  connected with the brush arm  161 . The brush head  162  is pivoted on the brush arm  161 . The brush arm  161  is designed to move along X, or Z direction. In certain embodiments, the brush head  162  is swiveled by the brush arm  161  for cleaning the second layer  222  of the plate  22 . In other words, the brush  16  is designed to travel in a lower portion  17  of the container  51 . 
         [0074]      FIG. 17  is an apparatus  70   d  according to some embodiments of the present disclosure. The apparatus  70   d  includes a heating element  18 , which is used to dehydrate the plate  22  in the third mode. In certain embodiments, the heating element  18  is an IR lamp, which dehydrates the plate  22  by irradiation. In some other embodiments, the heating element  18  is an electric heating device, which blows hot air to dry the plate  22 . 
         [0075]      FIG. 18  is an apparatus  70   e  according to some embodiments of the present disclosure. The container  51   a  is in a conical shape. The exit  11  is disposed at the bottom of the container  51   a.  The apparatus  70   e  includes an electric dipole  19  which is disposed at the bottom surface  55   a  of the container  51   a.  The electric dipole  19  is designed for detaching the particles from the second layer  222  of the plate  22  through electric attraction force. In certain embodiments, the electric dipole  19  is disposed adjacent to the plate  22  during a predetermined mode for maximizing the electric attraction force between the electric dipole  19  and particles in the plate  22 . In some other embodiments, the electric dipole  19  is disposed between the plate  22  and the container  51  as previously discussed to detach the particles. 
         [0076]      FIG. 19  is an apparatus  70   f  according to some embodiments of the present disclosure. The apparatus  70   f  has a container  51   b  including a first wall  511  and a second wall  512 . The height of the second wall  512  is higher than the height of the first wall  511 . The second wall  512  surrounds the first wall  511 . The inlet  59  is disposed at the bottom of the first wall  511  while the exit  11  is disposed around the inlet  59 . Because the sonicator  30  is coupled to the first wall  511 , the first wall  511  is agitated to form the ultrasonic wave. The inlet  59  is disposed under the plate  22  and form a flow to detach the particles trapped into the plate  22 . 
         [0077]      FIG. 20  is an apparatus  70   g  according to some embodiments of the present disclosure. The apparatus  70   g  includes a nozzle  15   a,  which is connected with the inlet  59 . In other words, the nozzle  15   a  is in the container  51   b . The nozzle  15   a  is used to from a turbulence of flow toward the second layer  222  of the plate  22  and to detach the particles from the plate  22 . 
         [0078]    A method of cleaning a plate designed to clean a wafer surface is through a stream of flow, a turbulence of flow, a mechanical cleaning force or a combination thereof. The method includes a number of operations and the description and illustration are not deemed as a limitation as the order of the operations. 
         [0079]    A term “moving” or “moved” is used in the present disclosure to describe an operation of locating an object to a specific site. The moving operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, a moving operation includes locating a plate to a container, a tank or a cup. In certain embodiments, a moving operation includes locating a plate to a position during a specific mode. 
         [0080]    A term “immersing” or “immersed” is used in the present disclosure to describe an operation of covering an object with a liquid. The liquid is a hydrophilic solvent or a hydrophobic solvent. The immersing operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, an immersing operation includes covering a portion of the object. For instance, immersing the plate indicates immersing the second layer instead of the first layer, which is disposed on the second layer. 
         [0081]    A term “applying” or “applied” is used in the present disclosure to describe an operation of enforcing a power on an object or an intermediate. The applying operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the applying operation includes agitating the liquid to form the ultrasonic wave which is transferred toward the plate. 
         [0082]    A term “dehydrating” or “dehydrated” is used in the present disclosure to describe an operation of taking moisture out of an object. The dehydrating operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the dehydrating operation includes drying out the plate. In certain embodiments, the dehydrating operation includes heating the plate to remove the moisture. 
         [0083]    A term “sensing” or “sensed” is used in the present disclosure to describe an operation of receiving the reflected ultrasonic wave. The sensing operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the sensing operation includes receiving the reflected ultrasonic wave from the container. In certain embodiments, the sensing operation includes receiving the reflected ultrasonic wave from the wave reflector. 
         [0084]    A term “swiveling” or “swiveled” is used in the present disclosure to describe an operation of rotating an object corresponding to the container. The swiveling operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the swiveling operation includes rotating the plate parallel to the bottom surface of the container. 
         [0085]    A term “scrubbing” or “scrubbed” is used in the present disclosure to describe an operation of cleaning an object with gentle rubbing. The scrubbing operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the scrubbing operation includes rubbing a surface of the plate. 
         [0086]      FIG. 21  is a diagram of a method  300  for cleaning a plate designed for cleaning a wafer surface, according to some embodiments of the present disclosure. The method  300  includes several operations, which are discussed in detail with reference to  FIGS. 22 to 26 . At operation  302 , the plate  22  is moved to a container  51 . At operation  304 , the plate  22  is immersed into a liquid  40 . At operation  306 , a power of an ultrasonic wave is applied on the plate  22 . At operation  308 , the plate  22  is dehydrated. 
         [0087]    In  FIG. 22 , the loader  3  of the semiconductor wafer cleaning system  200   e  passes the semiconductor wafer  2  to the cup  6  and the wafer chuck  7  holds the semiconductor wafer  2  in the chamber  4 . The arm  21  moves the plate  22  to position  8  to clean the top surface  1  of the wafer  2  in the first mode. After the first mode, the plate  22  is moved to position  9  so as to perform the second mode. In the second mode, the plate  22  is cleaned in the container  51  of the clean unit  50 . At position  9 , the particles trapped in the plate  22  are detached by the particle removal component. Finally, the plate  22  is moved from position  9  to position  58 , where the plate  22  is located in the IPA tank  57  and dehydrated in the third mode. 
         [0088]    In some embodiments, the semiconductor wafer cleaning system  200   e  drives the arm  21  to pivot the plate  22  above a semiconductor wafer  2  in the first mode. The power of the ultrasonic wave is applied to the plate  22 , which generates ultrasonic waves working as brushes for cleaning the top surface  1 . 
         [0089]      FIG. 23  is corresponding to the operation  302  in  FIG. 21 . In the second mode as in  FIG. 23 , the semiconductor wafer cleaning system  200   e  operates the arm  21  to place the plate  22  in the container  51  of the clean unit  50 . The plate  22  is disposed parallel to the bottom surface  55  of the container  51 . The wave sensor  24  is coupled to the plate  22  through the electric wire  25 . The sonicator  30  is coupled to the plate  22  through the wire  31 . Thus, the wire  31  and the electric wire  25  are placed into the container  51  after the operation  302  is performed. 
         [0090]      FIG. 24  is corresponding to the operation  304  in  FIG. 21 . The plate  22  is immersed into the liquid  40 . The liquid  40  flows into the container  51  through the opening  52 . The liquid  40  is, but not limited, selected from a citric acid solution, a formic acid solution and an ammonia solution. The percentage of citric acid in the citric acid solution by mass is, but not limited, from about 0.2% to about 2%. In some embodiments, the percentage thereof is from about 0.1% to about 1.8%. In some other embodiments, the percentage thereof is from about 0.5% to about 2.1%. In addition, the percentage of ammonia in the ammonia solution by mass is, but not limited, from about 0.4% to about 4%. In some other embodiments, the percentage thereof is from about 0.9% to about 1.8%. In certain embodiments, the percentage thereof is from about 2.1% to about 3.5%. 
         [0091]    In some embodiments, swiveling the second layer  222  along X or Y direction in the container  51  agitates the turbulence of the liquid  40  around the plate  22  so as to efficiently clean the plate  22 . In certain embodiments, an operation of scrubbing the surface of the plate  22  by the mechanical cleaning force is performed to clean the plate  22  in the liquid  40 , which is used to carry the particles from the plate  22 . 
         [0092]      FIG. 25  is corresponding to the operation  306  in  FIG. 21  that a power P of an ultrasonic wave W is applied on the plate  22 . In some embodiments, the sonicator  30  applies the power P to the plate  22 . Because the second layer  222  includes piezoelectric material, the power P is converted into a physical vibration, which causes the liquid  40  to generate the ultrasonic wave W around the second layer  222 . The ultrasonic power is used to detach the particle  60  from the second layer  222 . 
         [0093]    In some embodiments, the ultrasonic wave W is reflected from the bottom surface  55  so as to form a reflected ultrasonic wave RW. The second layer  222  senses the reflected ultrasonic wave RW and generates the reflected signal R. In other words, the method  300  includes an operation of sensing a reflected ultrasonic wave RW, which is reflected from the container  51 . 
         [0094]      FIG. 26  is corresponding to the operation  308  in  FIG. 21 . The plate  22  is immersed into the isopropyl alcohol  71  so as to remove the water molecule attached to the plate  22 . 
         [0095]    In some embodiments, the IPA tank  57  is filled with a non-polar solvent selected from pentane, hexane, cyclohexane, benzene, toluene, chloroform, and diethyl ether. The non-polar solvent is used to replace the wafer molecule around the plate  22  and easily evaporates when the plate  22  is disposed above the non-polar solvent. In some other embodiments, the dehydrating operation  308  is implemented in the container  51 . The container  51  accommodates the non-polar solvent selected from isopropyl alcohol, pentane, hexane, cyclohexane, benzene, toluene, chloroform, and diethyl ether. The non-polar solvent is able to generate the ultrasonic wave or the stream of flow for cleaning the plate  22  and to dehydrate the plate  22  at the same time. 
         [0096]    In some embodiments, an apparatus for cleaning a plate designed for cleaning a wafer surface includes a container, an exit, and a sonicator. The container includes an opening and a bottom surface. The opening is configured to receive the plate and the bottom surface, which is under the plate during a predetermined mode. The exit is disposed in the container. The sonicator is coupled to the container and applies an ultrasonic wave on the plate during the predetermined mode. 
         [0097]    In some embodiments, a semiconductor wafer cleaning system includes a plate, an arm, a sonicator and a clean unit. The plate is configured to clean a wafer during a run mode. The arm is pivoted to the plate and controls the position of the plate. The sonicator is coupled to the plate. The clean unit is configured to receive the plate during a self-clean mode. 
         [0098]    In some embodiments, a method for cleaning a plate designed for cleaning a wafer surface includes moving the plate to a container. The method also includes immersing the plate into a liquid. The method also includes applying a power of an ultrasonic wave on the plate. The method also includes dehydrating the plate. 
         [0099]    Although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter of the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. 
         [0100]    Various operations of embodiments are provided herein. The order in which some or all of the operations are described should not be construed as to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated by one skilled in the art having the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. It will be appreciated that layers, features, elements, etc. depicted herein are illustrated with particular dimensions relative to one another, such as structural dimensions or orientations, for example, for purposes of simplicity and ease of understanding and that actual dimensions of the same differ substantially from that illustrated herein, in some embodiments. 
         [0101]    Further, unless specified otherwise, “first,” “second,” or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. For example, a first channel and a second channel generally correspond to channel A and channel B or two different or two identical channels or the same channel. 
         [0102]    As used in this application, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application are generally to be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to “comprising”.