Abstract:
A method for operating a polishing head is provided. The method includes keeping a stator of at least one electromagnetism actuated pressure sector stationary with respect to a carrier head, and electromagnetically and linearly moving an active cell of the electromagnetism actuated pressure sector with the stator to linearly move the active cell with respect to the carrier head.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a divisional application of a non-provisional application Ser. No. 14/058,054, filed Oct. 18, 2013, which is herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    In general, the current design of a polishing head of a chemical-mechanical polishing system allows a control on its polish profile. However, this control only allows for the zones along the radial directions. Thus, there is a problem when there is an asymmetric topography of the polish profile. 
         [0003]    On the other hand, the current method of profile control utilizes the deformation of the membrane by pneumatic mechanism However, the application of pneumatic pressure is sometimes technically out of control, affecting the polish profile of the polishing head. 
         [0004]    Therefore, there is a need to solve the above deficiencies/problems. 
     
    
     
       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 noted 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]      FIG. 1  shows schematically a general arrangement of the polishing head in a chemical-mechanical polishing system according to some embodiments in the present disclosure. 
           [0007]      FIG. 2  shows schematically a bottom view of the electromagnetism actuated pressure sectors of  FIG. 1 . 
           [0008]      FIG. 3  shows schematically a bottom view of the electromagnetism actuated pressure sectors according to some embodiments of the present disclosure. 
           [0009]      FIG. 4  shows schematically a sectional view of the electromagnetism actuated pressure sectors in  FIG. 1 . 
           [0010]      FIG. 5  shows schematically a sectional view of the electromagnetism actuated pressure sectors according to some embodiments of the present disclosure. 
           [0011]      FIG. 6  shows schematically a drawing of the polishing head according to some embodiments of the present disclosure. 
           [0012]      FIG. 7  shows schematically a drawing of the polishing head according to some embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically depicted in order to simplify the drawings. 
         [0014]    Chemical-mechanical polishing is a process in which an abrasive slurry and a polishing pad work simultaneously together in both the chemical and mechanical approaches to flaten a substrate, or more specific a wafer.  FIG. 1  is a schematic view of a chemical-mechanical polishing system according to some embodiments of the present disclosure. As shown in  FIG. 1 , the chemical-mechanical polishing system includes a polishing head  100 , a platen  200 , and a slurry introduction mechanism  300 . The polishing head  100  includes a carrier head  110 , at least one electromagnetism actuated pressure sector  120 , and a membrane  130 . The electromagnetism actuated pressure sector  120  is disposed on the carrier head  110 . As shown in  FIG. 1 , a plurality of the electromagnetism actuated pressure sectors  120  are arranged on the carrier head  110 . The membrane  130  covers the electromagnetism actuated pressure sectors  120 . Meanwhile, the platen  200  is disposed below the polishing head  100 , and the slurry introduction mechanism  300  is disposed above the platen  200 . 
         [0015]    When the chemical-mechanical polishing system is in use, a polishing pad P is disposed on the platen  200 . The polishing head  100  holds a substrate W against the polishing pad P. Both the polishing head  100  and the platen  200  are rotated, and thus both the substrate W and the polishing pad P are rotated as well. The slurry introduction mechanism  300  supplies and deposits slurry S onto the polishing pad P. The cooperation between the slurry S and the polishing pad P removes material on the substrate W and tends to even out any irregular topography, making the substrate W flat or planar. 
         [0016]    When the chemical-mechanical polishing system is in use, a downward pressure/down force F is applied to the polishing head  100 , pushing the substrate W against the polishing pad P. Furthermore, localized pressures may be applied to the substrate W in order to control the polish profile of the substrate W. This can be achieved by the electromagnetism actuated pressure sectors  120 . The electromagnetism actuated pressure sectors  120  are sectors that can be individually and electromagnetically actuated to push the substrate W against the polishing pad P. 
         [0017]      FIG. 2  is a bottom view of the electromagnetism actuated pressure sectors  120  of  FIG. 1 . As shown in  FIG. 2 , the electromagnetism actuated pressure sectors  120  are at least partially arranged along at least one circumferential line relative to a center axis C of the carrier head  110 . That is, at least two of the electromagnetism actuated pressure sectors  120  are located on the same circumferential line relative to the center axis C of the carrier head  110 . In this way, the profile control of the substrate W can be carried out along at least one circumferential line relative to the center axis of the substrate W. In  FIG. 2 , the electromagnetism actuated pressure sectors  120  are arranged in substantially circumferential and radial lines relative to the center axis C of the carrier head  110 . 
         [0018]    As shown in  FIG. 1 , the membrane  130  abuts against the electromagnetism actuated pressure sectors  120 . More specifically, the membrane  130  is divided into a plurality of zones  132 . The zones  132  of the membrane  130  respectively abut against the electromagnetism actuated pressure sectors  120 . The displacements of the zones  132  of the membrane  130  are controlled by the respective electromagnetism actuated pressure sectors  120 . 
         [0019]    In the operational point of view, the profile control of the substrate W can be carried out by individually and electromagnetically actuating at least two of the electromagnetism actuated pressure sectors  120  on the same circumferential line relative to the center axis of the substrate W. That is, with a plurality of the electromagnetism actuated pressure sectors  120  being individually and electromagnetically actuated, the electromagnetism actuated pressure sectors  120  on the same circumferential line relative to the center axis of the substrate W can apply different forces to the substrate W, thereby applying the localized pressures to the substrate W. Since the localized pressures can be applied to the substrate W, the asymmetry topography on the substrate W can be handled. 
         [0020]    A quantity of the electromagnetism actuated pressure sectors  120  arranged on the carrier head  110  can range from about 5 to about 400. Technically speaking, the area of at least one of the zones  132  can be as small as about 1×1 cm 2 . This can facilitate a more precise profile control of the substrate W to be polished, and the profile discontinuity of the removal rate is reduced as well. 
         [0021]      FIG. 3  is a bottom view of the electromagnetism actuated pressure sectors  120  according to some embodiments of the present disclosure. In practice, the pattern arrangement of the electromagnetism actuated pressure sectors  120  on the carrier head  110  has a high flexibility, with the area of at least one of the zones  132  can be technically as small as about 1×1 cm 2 , as mentioned above. As shown in  FIG. 3 , the electromagnetism actuated pressure sectors  120  are at least partially arranged in at least one row and at least one column. 
         [0022]      FIG. 4  is a schematic sectional view of the electromagnetism actuated pressure sectors  120  of  FIG. 1 . The carrier head  110  has at least one opening  111  therein. At least one of the electromagnetism actuated pressure sectors  120  includes a permanent magnet  121 , a coil assembly  123 , and a sector plate  125 . The permanent magnet  121  is located in the opening  111 . The coil assembly  123  is telescopically received in the opening  111  and in cooperation with the permanent magnet  121 . The sector plate  125  is connected to the coil assembly  123 . 
         [0023]    The profile control of the substrate W to be polished is achieved by the individual motions of the electromagnetism actuated pressure sectors  120 , or more specific the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120  relative to the carrier head  110 . The working principle of the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120  relative to the carrier head  110  is as follows. The permanent magnet  121  in the opening  111  generates a magnetic field. Within this magnetic field, when an electric current flows through the coil assembly  123 , according to the Fleming&#39;s left-hand rule, the coil assembly  123  experiences an electromagnetic force. This electromagnetic force is perpendicular to both this magnetic field generated and to the flow direction of the electric current, causing the movement of the coil assembly  123 . 
         [0024]    The flow direction of the electric current controls the direction of the movement of the coil assembly  123 . Without loss of generality, in some embodiments of the present disclosure, when the electric current flows in one direction, for example, a clockwise direction, through the coil assembly  123 , the electromagnetic force generated will move the coil assembly  123  and the sector plate  125  away from the carrier head  110 . In contrast, when the electric current flows in another direction, for example, an anti-clockwise direction, through the coil assembly  123 , the electromagnetic force generated will move the coil assembly  123  and the sector plate  125  close to the carrier head  110 . The individual movements of the sector plates  125  will consequently move the respective zones  132  of the membrane  130  since the membrane  130  abuts against the sector plates  125  of the electromagnetism actuated pressure sectors  120 . 
         [0025]    The magnitude of the electromagnetic force generated is proportional to the amount of the electric current flowing through the coil assembly  123 . Therefore, the displacement of the sector plate  125  and thus the displacement of the respective zone  132  of the membrane  130  are proportional to the amount of the electric current flowing through the coil assembly  123 . 
         [0026]    Moreover, in some embodiments of the present disclosure, the flow direction and the amount of the electric current flowing through each coil assembly  123  can be controlled by an integrated circuit. Therefore, the direction and the magnitude of the corresponding electromagnetic force which the coil assembly  123  experiences can be digitally, individually and precisely controlled. Consequently, the directions and the magnitudes of the movements of the sector plates  125  and thus the respective zones  132  of the membrane  130  can be digitally, individually and precisely controlled by the integrated circuit. In this way, a gradient control of the movements of the zones  132  of the membrane  130  can be achieved. 
         [0027]    As shown in  FIG. 4 , at least one of the electromagnetism actuated pressure sectors  120  further includes an elastic element  127  connecting the sector plate  125  to the carrier head  110 . In some embodiments of the present disclosure, the elastic element  127  elongates when the sector plate  125  is moved away from the carrier head  110  by the electromagnetic force generated by the electric current flowing through the coil assembly  123 . When the flow of the electric current is stopped, the elastic element  127  will release the potential energy stored during its elongation, and the elastic element  127  will go back to its natural length. In contrast, the elastic element  127  shortens when the sector plate  125  is moved close to the carrier head  110  by the electromagnetic force generated by the electric current flowing through the coil assembly  123 . Similarly, when the flow of the electric current is stopped, the elastic element  127  will release the potential energy stored during its shrinkage, and the elastic element  127  will go back to its natural length. 
         [0028]    In some embodiments of the present disclosure, the positions of the permanent magnet  121  and the coil assembly  123  can be exchanged.  FIG. 5  is a schematic sectional view of the electromagnetism actuated pressure sectors  120  according to some embodiments of the present disclosure. The coil assembly  123  is located in the opening  111 . The permanent magnet  121  is telescopically received in the opening  111  and in cooperation with the coil assembly  123 . The sector plate  125  is connected to the permanent magnet  121 . In this arrangement, as shown in  FIG. 5 , at least one of the electromagnetism actuated pressure sectors  120  also includes the elastic element  127  connecting the sector plate  125  to the carrier head  110 . 
         [0029]    With a similar working principle, when an electric current flows through the coil assembly  123 , according to the right-hand grip rule, a magnetic field will be generated around the coil assembly  123 . The magnetic field generated around the coil assembly  123  will interact with the magnetic field generated by the permanent magnet  121 . Thus, an electromagnetic force is generated, causing the movement of the permanent magnet  121 . 
         [0030]    Again, similarly, the flow direction of the electric current controls the direction of the movement of the permanent magnet  121 , and thus the movement of the sector plate  125  of the electromagnetism actuated pressure sectors  120 . Moreover, the magnitude of the electromagnetic force generated is proportional to the amount of the electric current flowing through the coil assembly  123 . 
         [0031]    As shown in  FIGS. 4-5 , the membrane  130  abuts against the sector plates  125  of the electromagnetism actuated pressure sectors  120 . In this way, the zones  132  of the membrane  130  can respond instantly to the movements of the respective sector plates  125  of the electromagnetism actuated pressure sectors  120 . Moreover, the membrane  130  acts as a chemical-proof layer to prevent chemicals or the slurry from getting contact with the electromagnetism actuated pressure sectors  120 . In some embodiments of the present disclosure, the material of the membrane  130  is plastic. 
         [0032]      FIG. 6  is a schematic drawing of the polishing head  100  according to some embodiments of the present disclosure. As shown in  FIG. 6 , the polishing head  100  further includes a receiver  150  and a controller  140 . The receiver  150  is connected to the controller  140 , and the controller  140  is connected to the electromagnetism actuated pressure sectors  120 . The receiver  150  is used for obtaining a pre-polished process data. On the other hand, the controller  140  is used for controlling the motions of the electromagnetism actuated pressure sectors  120 , or more specific the movements of the sector plate  125  of the electromagnetism actuated pressure sectors  120 , according to the pre-polished process data. 
         [0033]    When the chemical-mechanical polishing system is in use, the receiver  150  obtains a pre-polished process data. The pre-polished process data may represent a pre-polished profile of the substrate W, a surface temperature of the substrate W, an electric resistance of the substrate W, etc., or any combinations thereof. Then, the controller  140  can control the motions of the electromagnetism actuated pressure sectors  120 , or more specific the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 , according to the pre-polished process data. 
         [0034]    In the operational point of view, the sector plates  125  are electromagnetically actuated according to the pre-polished process data. For example, when the received pre-polished process data represents that the substrate W is thicker at the center of the substrate W, the controller  140  will control the electromagnetism actuated pressure sectors  120  to provide more pressure to the center of the substrate W when both the polishing head  100  and the platen  200  are rotated. 
         [0035]    Furthermore, the polishing head  100  includes the controller  140  for in-situ controlling the motion of the electromagnetism actuated pressure sectors  120 . When the chemical-mechanical polishing system is in use, the controller  140  can in-situ control the motion of the electromagnetism actuated pressure sectors  120 , or more specific the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 , as well. That is, the controller  140  can control the motions of the electromagnetism actuated pressure sectors  120 , or more specific the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 , when both the polishing head  100  and the platen  200  are rotated. 
         [0036]    More specifically, when the chemical-mechanical polishing system is in use, the receiver  150  can obtain an in-situ process data. The in-situ process data may represent an in-situ profile of the substrate W, a surface temperature of the substrate W, an electric resistance of the substrate W, etc., or any combinations thereof. Then, the controller  140  can in-situ control the motion of the electromagnetism actuated pressure sectors  120 , or more specific the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 , according to the in-situ process data. 
         [0037]    In the operational point of view, the sector plates  125  are electromagnetically actuated when both the substrate W and the polishing pad P are rotated. For example, when the received in-situ process data represents that the substrate W is thicker at the center of the substrate W, the controller  140  will control the electromagnetism actuated pressure sectors  120  to provide more pressure to the center of the substrate W when both the polishing head  100  and the platen  200  are rotated. 
         [0038]    In practice, as aforementioned, the controller  140  controls the motions of the electromagnetism actuated pressure sectors  120  by the electric current. Or more specifically, the controller  140  controls both the direction and the magnitude of the movements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 , and this is achieved by the adjustment of the flow direction and the magnitude of the electric current. Thus, the control of the polish profile can be precisely digitalized. 
         [0039]      FIG. 7  is a schematic drawing of the polishing head  100  according to some embodiments of the present disclosure. As shown in  FIG. 7 , the polishing head  100  further includes a sensor  160  and a calibrator  170 . The carrier head  110 , the electromagnetism actuated pressure sectors  120 , the sensor  160 , and the calibrator  170  are connected to one another. The sensor  160  is used for sensing the displacements of the electromagnetism actuated pressure sectors  120 , or more specific the displacements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 . The calibrator  170  is used for calibrating the carrier head  110  according to the sensed displacements of the electromagnetism actuated pressure sectors  120 , or more specific the displacements of the sector plates  125  of the electromagnetism actuated pressure sectors  120 . 
         [0040]    After the prevention maintenance of the chemical-mechanical polishing system, the sensor  160  can be used to sense the displacement of the sector plate  125  of at least one of the electromagnetism actuated pressure sectors  120 . In other words, this is to check for a residual displacement remained after the movements of the sector plate  125  of the electromagnetism actuated pressure sector  120 . A reason for a residual displacement of the sector plate  125  is that the potential energy stored in the elastic element  127  is not substantially released after the displacement of the sector plate  125 . Thus, the elastic element  127  has not gone back to its natural length, and the residual displacement is formed. Another reason is that the natural length of the elastic element  127  has changed. Thus, the elastic element  127  does not go back to the original natural length, even though the potential energy stored during the displacement of the sector plate  125  is substantially released. Whatever the reason, the calibrator  170  can then calibrate the carrier head  110  according to the sensed displacement of the sector plate  125  of at least one of the electromagnetism actuated pressure sectors  120 . In this way, the performance of the polishing head  100  is maintained. 
         [0041]    In some embodiments of the present disclosure, the polishing head  100  for the chemical-mechanical polishing system includes the carrier head  110 , at least one electromagnetism actuated pressure sector  120  and the membrane  130 . The electromagnetism actuated pressure sectors  120  are arranged on the carrier head  110 . The membrane  130  covers the electromagnetism actuated pressure sectors  120 . 
         [0042]    In some embodiments of the present disclosure, the chemical-mechanical polishing system includes the polishing head  100 , the platen  200  and the slurry introduction mechanism  300 . The polishing head  100  includes the carrier head  110 , a plurality of the electromagnetism actuated pressure sectors  120  and the membrane  130 . The electromagnetism actuated pressure sectors  120  are arranged on the carrier head  110 . The membrane  130  covers the electromagnetism actuated pressure sectors  120 . Meanwhile, the platen  200  is disposed below the polishing head  100 , and the slurry introduction mechanism  300  is disposed above the platen  200 . 
         [0043]    In some embodiments of the present disclosure, the method of polishing a substrate W includes supplying the slurry S onto the polishing pad P, holding the substrate W against the polishing pad P, electromagnetically actuating a plurality of electromagnetism actuated pressure sectors  120  to push the substrate W against the polishing pad P, and relatively rotating the polishing pad P and the substrate W. 
         [0044]    Although the present disclosure has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, their spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
         [0045]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present disclosure without departing from the scope or spirit of the present disclosure. In view of the foregoing, it is intended that the present disclosure covers the modifications and variations of the present disclosure provided they fall within the scope of the following claims.