Patent Publication Number: US-2006000806-A1

Title: Substrate carrier for surface planarization

Description:
FIELD OF THE INVENTION  
      Embodiments of the present invention relate to a substrate carrier adapted to enhance substrate surface planarization in processes such as chemical mechanical planarization (CMP). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Embodiments of the present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.  
       FIG. 1  illustrates a perspective view of a substrate processing apparatus in accordance with an embodiment of the present invention;  
       FIG. 2  illustrates an enlarged cross-sectional view of a substrate processing apparatus in accordance with an embodiment of the present invention;  
       FIG. 3  illustrates an enlarged cross-sectional view of a substrate processing apparatus in accordance with an embodiment of the present invention;  
       FIG. 4  illustrates an enlarged cross-sectional view of a substrate processing apparatus in accordance with an embodiment of the present invention;  
       FIG. 5  illustrates a method of enhancing CMP using actuator to cause localized deflections in accordance with and embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION  
      In the following detailed description, reference is made to the accompanying drawings which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments in accordance with the present invention is defined by the appended claims and their equivalents.  
      Embodiments of the present invention relate to the processing of substrates such as semiconductor wafers and/or metalized layers in semiconductor devices, using a substrate carrier configured to provide localized control of surface planarization during a CMP process. Embodiments of the present invention may allow for the processing of a substrate using, for example, very low pressures, high rotational velocity, and manipulation of other parameters that may be particularly useful for planarization of ultra low-K substrates to help resist mechanical damage during the substrate processing step.  
       FIG. 1  illustrates a perspective view of a substrate processing apparatus in accordance with an embodiment of the present invention. A CMP apparatus  10 , may include a slurry/solution delivery system  12 , a processing element  16  and a processing element carrier  14 . Processing element  16  may be, for example, a polishing pad and the processing element carrier  14  may be a rotatable platen adapted to provide a substantially planar turntable to support a processing element  16 .  
      Substrate carrier  20  may be configured to support a substrate  22  in a substantially opposing relationship with the processing element  16  (processing relationship). Substrate carrier  20  may also be adapted to movably position the substrate  22  in an urging engagement with the processing element  16  to effect a planarization or polishing of the process side  24  of substrate  22 . Substrate carrier  20  may be configured to rotate, oscillate, or otherwise move as needed to induce processing of the process side  24  of substrate  22 .  
      Slurry delivery system  12  may include one or more nozzles  27  positioned adjacent the surface  18  of processing element  16  for the dispensing of a slurry/solution  28  thereon. During a polishing/planarization step, for example, a slurry  28  containing a liquid, such as, but not limited to, deionized water for oxide polishing and a pH adjuster, such as potassium hydroxide also for oxide polishing, can be supplied to the surface  18  of processing element  16  by the slurry arm  12 , and may help facilitate removal of material from process side  24  of substrate  22 . Slurry  28  can also include abrasive particles, including, but not limited to, silicon dioxide for oxide polishing.  
       FIG. 2  illustrates an enlarged cross-sectional view of a substrate processing apparatus in accordance with an embodiment of the present invention and  FIG. 3  illustrates an enlarged view of the substrate carrier of  FIG. 2  in accordance with an embodiment of the present invention. Substrate carrier  20  may include a housing  26  having a cavity  28  disposed therein, and a backing plate  44 . Backing plate  44  may be configured to couple to a backside  23  of a substrate  22  and assist in retaining substrate  22  during processing. Substrate  22  may have a process side  24  that may require polishing or planarizing to remove certain layers of material.  
      Substrate carrier  20  may also include an array of actuators  32  disposed within the body of housing  26 , and in the illustrated embodiment may be disposed in cavity  28  of housing  26 . Actuators  32  may be adapted to independently and controllably urge one or more localize portions of substrate  22  to be in respectively the same or different greater degrees of processing engagement with process element  16 . The one or more localized deflections of the substrate may in turn enhance planarization at that point or points. Actuators  32  may take a number forms and be actuated or driven in several ways.  
      In one embodiment of the invention, actuators  32  may be electrically driven and include, for example, an impingement pin  34  that has a first end  40  and a second end  41 . Impingement pin  34  may project from within cavity  28  through an actuator bore  36  in backing plate  44  in a linearly movable fashion. First end  40  may be configured for engagement with the backside  23  of substrate  22 . A portion of the impingement pin  34  may also pass through a solenoid  38 , such as an electrically conductive coil winding, also housed within cavity  28 . Solenoid  38  may be configured to selectively move impingement pin  34  within actuator bore  36  by changing the current magnitude and/or flow through solenoid  38 .  
      The solenoid  38  may be energized by a controllable electricity source  60 , such that the current supplied to coil  34  may be varied. Applying a current may cause first end  40  of impingement pin  34  to push against backside  23  such that a local deflection of substrate  22  may result. Such a deflection may urge the process side of the localized deflection to be in greater contact with processing element  18  and thus may enhance the planarization of the localized area. Likewise, changing the current (e.g. reversing the current flow) may result in a retraction of impingement pin  34 , which in turn may relive the deflection to reduce the enhanced planarization caused by the local deflection.  
      Controlling the deflections of certain substrate portions may provide for selective local control of material removal from the process side  24  of substrate  22 . As illustrated in  FIG. 3 , impingement pin  34  may extend through solenoid windings  38  and through actuator bore  36  such that first end  40  is in a deflecting engagement with substrate  22  resulting in a localized deflection  48 . To control localized deflection  48 , the electricity source  60  may be coupled to a controller  62 . Controller  62  may control the magnitude and direction of current flow through solenoid windings  38 , which may in turn cause the impingement pin  32  to linearly move as shown by directional arrows  46 .  
      In one embodiment of the present invention, controller  62  may include, but is not limited to, an electronic computer. The computer may include, a CPU, memory, buses, I/O ports all suitably interconnected to electricity source  60  and configured to control the linear actuation of impingement pin  34 . In one embodiment of the invention, software instructions and data can be coded and stored within the memory for causing the controller  62  to generate suitable signals to each solenoid  38  to control the movement of the first end  40  of the impingement pin  34  into and out of forcible engagement with backside  23 . In alternate embodiments, application specific integrated circuits (ASIC), or other special purpose hardware may be employed to implement controller  62 .  
      In one embodiment of the present invention, an end point detection device  64  may also be in communication with controller  62 , and configured to detect and/or monitor the processing of the process side  24  of substrate  22 . End point detection device  64  may be a suitable device currently used.  
      During the processing of substrate  22 , should a localized area of substrate  22  need more aggressive polishing, as may be determined by end point detection device  64 , the end point detection device  64  may send a signal to controller  62 . Controller  62  may in turn cause electricity source  60  to modify/change the current to solenoid  38  as needed to cause the first end  40  of impingement in  34  to increase engaging pressure against the backside  23 . This increased pressure may generate localized deflection  48 , which in turn may enhance localized planarization of substrate  22 . Upon reaching a desired planarization, again as may be detected by end point detection device  64 , the reverse process may occur such that the amount of deflection may be reduced to reduce the amount of localized planarization.  
       FIG. 4  illustrates an enlarged cross-sectional view of a substrate carrier in accordance with an embodiment of the present invention. Substrate carrier  420  may have a housing  426  configured to retain a substrate  422  in a generally opposing relationship with a processing element  416  for planarizing/polishing of a process side  424 . Substrate carrier  420  may include a cavity  428 , and a backing plate  444 , which may be adapted to retain substrate  422  in a processing relationship with process element  416  during planarization.  
      A plurality of actuators  400  (shown in both configurations A and B) may be positioned within cavity  248  of substrate carrier  420 . Actuators  400  may be pneumatically driven, and include a movable piston  402  and a cylinder  404  that may be chargeable with air or other gas. Piston  402  may be configured to controllably slide in and out of cylinder  404  based on a signal input and a charging and exhausting of air from cylinder  404 . Piston  402  may be configured to extend from cylinder  404  through actuator bore  436  in backing plate  444 , and have a first end  440  configured for engagement with backside  423 . Actuators  400  may be in communication with a pneumatic controller  460 , which may selectively and independently control the actuation of pistons  402  by controlling the supply of air to individual pneumatic actuators  400  through supply lines  401 .  
      CMP systems typically include a number of pneumatically operated subsystems and actions. Accordingly, in one embodiment, the pneumatic source to the pneumatic controller  460  may be from a general source responsible for those other pneumatic operations. In one embodiment, an independent pneumatic source, such as a compressor or pressurized cylinder, may be in communication with pneumatic controller  460  and may also be incorporated in the substrate carrier  420 .  
      To urge enhanced removal of material from a localized area of the process side  424  of substrate  422 , pneumatic controller  460  may activate pneumatic actuator  400 , such that piston  402  is forced out of cylinder  404 , first end  440  may be urged against backside  423  of substrate  422 . Illustrated as pneumatic actuator configuration  400 A, when piston  402  is in the extended position, it may cause a localized deflection  448  in substrate  422 . Localized deflection  448  may enhance the removal of material at the area of deflection on the process side  424 , as this area will be in a greater degree of contact with processing element  416 .  
      In areas where material from the process side  424  does not need further removal, for example, the pneumatic actuator  400  may be in state where air from the cylinder  404  is removed such that piston  402  may at least partially retract into cylinder  404 , as shown by pneumatic actuator configuration  400  B. With piston  402  retracted, there may be no affirmative substrate deflection, which in turn may de-emphasize contact between a localized area and process element  416 . Piston  402  may be controllably retracted and extended between the range of movement  406 , such that the amount of localized deflection  448  may be controlled anywhere from a maximum deflection state to a minimum or no deflection state, depending on the processing status.  
      An end point detector  462  may be utilized to monitor the planarization of the process side  424  of substrate  422 . End point detection device  462  may generate signals corresponding to various planarization states, and be configured to send such signals to pneumatic controller  460 . Depending on the state of planarization (uniformity, degree of material removal, overall planarization, etc.), pneumatic controller  462  may in turn selectively control actuation of the independent pneumatic actuators, and thus control the level of enhanced planarization and material removal at various localized areas on the process side  424 .  
      In one embodiment of the invention, the actuator bores  436  may be configured to be controllably placed under a vacuum. Thus, when the actuators are not pushing against or in contact with the substrate backside  23 , the substrate may be held against the backing plate at the localized area. Further, if desired, the vacuum may cause a localized inverse deflection in order to de-emphasize the removal of material in that localized area.  
      In embodiments of the present invention, additional actuators may be used having different actuation mechanisms, including, but not limited to a screw drive mechanism, hydraulic actuated systems, magnetically controlled systems, as well as other drive mechanisms that may allow for selective localized deflection of the substrate  422  to enhance material removal from localized areas. The number and configuration of actuators used in accordance with embodiments of the present invention may vary depending on a variety of factors, including the substrate material being processed (e.g. material composition, thickness, number of layers, etc.), the processing stage, substrate size, and the like.  
      Further, embodiments of the invention, actuators may be positioned within the processing element carrier and configured to create localized deflections in the processing element, such as a polishing pad. These localized deflections may enhance the amount of material removal on the process side of the substrate opposite the localized deflection in the process element.  
       FIG. 5  illustrates a method of enhancing CMP using actuator to cause localized deflections in accordance with and embodiment of the present invention. A substrate may be provided having a backside and a process side in need of processing ( 500 ). A substrate processing apparatus may be provided that includes a substrate carrier adapted to retain the substrate during processing, and which may include a plurality of actuators disposed within the body of the substrate carrier, the plurality of actuators configured to independently and controllably apply a pressure to a backside of the substrate to cause at least a localized deflection of a process side of the substrate ( 510 ).  
      The plurality of actuators may be selectively actuated to create localized deflections in the substrate ( 520 ). The removal of material from the process side of the substrate at the localized deflections may be controlled by selectively varying the amount of localized deflections and thus varying the amount and degrees of interaction between the localized deflections and the process element ( 530 ).  
      In one embodiment of the present invention, substrate surface pattern information, such as lithography mask information, may accompany the particular substrate or lot of substrates to be processed. This information may be used by the controller of the processing apparatus to independently and/or collectively manipulate the actuators to control the planarization of the process side in order to enhance the localized processing, for example within die, die-to-die and within substrate planarization.  
      In one embodiment of the present invention, the actuators may also be equipped with temperature modulating capability to modulate local surface temperatures of the processing side of the substrate. This may allow for the creation of a difference in temperature in a local area or from one grouping of localized areas to another area of the surface by individually and/or collectively controlling the temperature modulation, which in turn may to enhance or suppress local removal rates. For example, the actuator may increase or decrease the temperature at one or more localized areas or groups of localized areas, while the temperature at other localized locations may be maintained or independently modulated.  
      Embodiments of the present invention may allow for he energy sources may be manufactured in a number of ways. In one embodiment, the actuators may be manufactured using micro machining technology and methodologies, such as Micro Electro Machining Systems.  
      Though certain substrate processing tool configurations were illustrated, embodiments of the present invention may also be applied to a number of different processing tool configurations and processes. Other tool configurations may include, but are not limited to, those having single processing elements, multiple processing elements, processing elements having simple and complex geometries, substrate holders having one or more electrically isolated regions, and/or multiple substrate holders.  
      Although certain embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that embodiments in accordance with the present invention may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments in accordance with the present invention be limited only by the claims and the equivalents thereof.