Abstract:
A substrate plating processor has a vessel on a support structure and a head support fixed in place relative to the support structure. A head having a rotor is attached to the head support. A lifter associated with the head support moves the head into and out of engagement with the vessel. An alignment assembly attachable to the rotor has at least one sensor adapted to detect a position of an inside surface of the vessel when the head is engaged with the vessel. The sensor may be a physical contact sensor positioned to contact the inside surface of the vessel.

Description:
TECHNICAL FIELD 
       [0001]    This application relates to chambers, systems, and methods for electrochemically processing micro-feature work pieces or substrates having micro-scale devices integrated in and/or on the substrate. 
       BACKGROUND 
       [0002]    Microelectronic devices, such as semiconductor devices and micro-mechanical or micro-optical devices are generally manufactured on and/or in a substrate using several different types of machines. In a typical manufacturing process, one or more layers of conductive materials, typically metals, are plated onto a substrate The substrate is then generally etched and polished to remove a portion of the deposited conductive layers, to form contacts and/or conductive lines. 
         [0003]    As micro-scale devices are increasingly manufactured at ever smaller microscopic sizes, the machines used in the manufacturing processes must also become more precise. When a metal layer plated onto a substrate, generally a highly uniform thickness over all areas of the substrate is required. Achieving a uniform plating profile or thickness requires precise control of electrical current flow in the plating chamber. This correspondingly requires that the substrate be accurately positioned and centered in the plating chamber. 
         [0004]    In most plating machines, the substrate is held in a fixture or a rotor in a head which moves the substrate from load/unload position to process position within a plating vessel holding electrolyte. Since the plating chamber is closed when the substrate is in the process position, it is not possible to visually align the substrate, or the head holding the substrate, with the vessel. Accordingly, there is a need for techniques for aligning the head with the vessel in substrate plating chambers. 
       SUMMARY OF THE INVENTION 
       [0005]    A substrate plating processor has a vessel on a support structure and a head support fixed in place relative to the support structure. A head having a rotor is attached to the head support. A lifter associated with the head support, for example in a lift/rotate mechanism, moves the head into and out of engagement with the vessel. An alignment assembly attachable to the rotor has at least one sensor for detecting a position of an inside surface of the vessel when the head is engaged with the vessel. The sensor may be a physical contact sensor positioned to contact the inside surface of the vessel. Other types of sensors, such as optical, acoustic, or other distance measuring sensors may optionally be used. Other and further objects and advantages will become apparent from the following detailed description of one embodiment of the invention. Other embodiments may of course be used within the scope of the invention. The invention resides as well in sub combinations of the elements and steps described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    In the drawings, the same element number indicates the same element in each of the views. 
           [0007]      FIG. 1  is a perspective view of a plating chamber. 
           [0008]      FIG. 2  is a front perspective view of the head of the plating chamber shown in  FIG. 1  with the head cover removed for illustration. 
           [0009]      FIG. 3  is a rear perspective view of the head shown in  FIG. 2 . 
           [0010]      FIG. 4 . is a section view of the head shown in  FIG. 1 . 
           [0011]      FIG. 5  is a perspective view of the alignment assembly shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    As shown in  FIG. 1 , a plating processor or chamber  20  has a head  30  attached to arm  44  of a lift/rotate mechanism  34 . The lift/rotate mechanism  34  can vertically lift and lower the head  30 , and also rotate the head  30  between a face-up and a face-down position. The head  30  is shown in the face-down position in  FIG. 1 , with the head  30  also engaged into a vessel assembly  50  supported on a deck plate  24 . 
         [0013]    Referring momentarily to  FIG. 4 , the head  30  includes a rotor  180  and optionally a backing plate  198  attached to the rotor  180 . A motor  184  in the head  30  rotates the rotor  180  during processing. During plating processing, a substrate, such as a silicon wafer, is held in the rotor  180  and rotated while in contact with a liquid electrolyte bath in the vessel assembly  50 . A diffuser  74  and an upper cup  76  in the vessel assembly  50  help to control both the electric field and flow of electrolyte within the plating chamber  30 . As shown in  FIG. 4 , when the rotor  180  is in the processing position, the plating chamber  20  is closed, and neither the rotor  180 , nor a substrate held in the rotor  180 , are visible. Visual alignment between the rotor  180  or the head  30  and the vessel assembly  50  accordingly cannot be achieved. 
         [0014]      FIG. 5  shows an alignment assembly  200  which may be used to precisely align the head  30  including the rotor  180  with the vessel assembly  50 . The specific alignment assembly example  200  shown includes first and second alignment position contact sensors  206  and  208 . The sensor  206  may be a horizontal position sensor and the sensor  208  may be a vertical position sensor. The sensors  206  and  208  are linked to a transmitter  210  within the alignment assembly housing  204 . A battery  212  may also be contained within the housing  204  and linked to the transmitter  210  and to the sensors. The housing  204  may include or be attached to a mounting ring  202 . In  FIG. 5 , the sensors are physical contact sensors oriented at right angles to each other, with the sensor.  208  substantially vertical and the sensor  206  substantially horizontal. In alternative designs,, a single sensor, or more than two sensors may be used, and different sensor orientations may be used. 
         [0015]      FIG. 4  shows the alignment assembly  200  attached to the rotor  180 . Specifically, the mounting ring  202  of the alignment assembly  200  is bolted onto the rotor  180 , while the head is in the face-up or load/unload position. If the rotor  180  includes a backing plate  198 , it may be removed before attaching the alignment assembly. The head  30  is then inverted and lowered via the lift/rotate mechanism  34  into the process position shown in  FIG. 4 . 
         [0016]    In one method for aligning the head  30  with the vessel assembly  50 , the head is first adjusted so that it is level. This may be achieved by first checking the orientation of the head using a digital level or similar manual measuring device. If the measuring device indicates that the head is not level, a first leveling operation may be performed using the manual measuring device and the leveling mechanism described below. 
         [0017]    If the digital level indicates the head is level, or after the first leveling operation is performed, a more precise measurement can be made by rotating the alignment assembly  200  within the vessel assembly  50 , via control of the motor  184 . As the alignment assembly  200  rotates, a readout from the vertical sensor  208  is transmitted to a nearby display, for example via radio frequency transmission. This provides an indication of the out-of-level condition or “sag” of the head, if any. 
         [0018]    Referring to  FIGS. 2 and 3 , the head  30  may be leveled using a leveling mechanism on the head. Various leveling mechanisms may be used to level the head, generally by exerting a pushing or pulling force between the arm  44  and the head  30 . In the example shown in  FIGS. 2 and 3 , a leveling mechanism operates by loosening locking bolts  47  and then advancing or retracting an adjusting screw  49 . The inner end of the adjusting screw  49  bears on an arm plate  46 . As the adjusting screw  49  is turned clockwise or tightened, it pulls the head plate  48  up, or clockwise in  FIG. 3 . The adjusting screw  49  may be turned while monitoring the display of the output of the vertical sensor  208 , as the alignment assembly continues to rotate. 
         [0019]    After the head  30  is leveled via the adjusting screw  49 , the locking bolts are tightened to fix the head  30  into the level position. If the display shows no indication of head sag, then these steps may be skipped as no sag adjustment of the head is necessary. If the digital level measuring device initially shows the head is out of level, then the head leveling steps described above may be performed until the digital leveling device indicates that the head is level, followed by use of the alignment assembly  200 , as described above. 
         [0020]    With the head  30  level, a readout from the horizontal sensor  206  is used to center the head relative to the vessel assembly  50 . This may be achieved by loosening the vessel clamps  51 , threaded fasteners, of similar devices which hold the vessel assembly  50  in place on the deck plate  24 , as shown in  FIG. 1 . The vessel assembly  50  may then be shifted horizontally on the deck plate  24 , until the readout from the horizontal sensor  206  remains substantially constant through an entire 360 degree rotation. A substantially constant readout from the horizontal sensor indicates that the head is aligned with the vessel assembly  50  about the vertical rotation axis of the rotor. The vessel assembly  50  may be moved horizontally by hand, or by optionally using one or more cam-action or a lever-action tools. The tools, if used, may be hand tools or they may be provided as a permanent part of the processor  20 . After the vessel assembly  50  is aligned with the head  30 , the clamps  51  are tightened. 
         [0021]    The lift/rotate mechanism may then be used to lift the head  30  up and away from the vessel assembly  50 , and rotate the head  30  back into a face-up position. The alignment assembly is then removed from the rotor. A substrate may then be loaded into the head and plated. Depending on the specific design of the rotor and the alignment assembly, one or more fixtures, such as contact rings, seal rings, etc. may optionally be attached to the rotor after the alignment assembly is removed and before processing is initiated. 
         [0022]    The sensors  206  and  208  may be differential variable reluctance transducer sensors (DVRT). This type of sensor outputs counts proportional to the movement of the tip  218  of the sensor arm  216 . For example, a 1 mm movement of the tip may result in an output of 500 counts, with one count equivalent to movement of 0.002 mm. Table 1 below describes one example of an alignment method that may be used. 
         [0000]    
       
         
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                 1 
                 Initial setup: 
               
             
          
           
               
                   
                 A. 
                 Establish wireless connection to the alignment assembly. 
               
               
                   
                 B. 
                 Verify connection by moving one of the sensors by hand. 
               
               
                   
                 C. 
                 Mount alignment assembly in place of the backing plate. 
               
             
          
           
               
                 2 
                 Verify Zero positions: 
               
             
          
           
               
                   
                 A. 
                 Move Lift to upper hard stop (Lift 0 position). 
               
               
                   
                 B. 
                 Move rotate to level ±0.1° with digital level. 
               
               
                   
                 C. 
                 Adjust Sag to level ±0.1° with digital level. 
               
               
                   
                 D. 
                 Spin so R indicator point to lift rotate (Spin 0 position). 
               
             
          
           
               
                 3 
                 Level 
               
             
          
           
               
                   
                 A. 
                 Spin to 0°. 
               
               
                   
                 B. 
                 Z down until Z Indicator reads 2000. 
               
               
                   
                 C. 
                 Spin to 180°. 
               
               
                   
                 D. 
                 Adjust Sag to 2000. 
               
               
                   
                 E. 
                 Spin to 90°. 
               
               
                   
                 F. 
                 Adjust Rotate to Z indicator reads 2000. 
               
             
          
           
               
                 4 
                 Find Center 
               
             
          
           
               
                   
                 A. 
                 Spin to 0°; record R Axis value (R0). 
               
               
                   
                 B. 
                 Spin to 180°; record R Axis value (R180). 
               
               
                   
                 C. 
                 Calculate Rtarget = (R0 + R180)/2 
               
               
                   
                 D. 
                 Move the vessel until indicator value = Rtarget. 
               
               
                   
                 E. 
                 Spin to 90°; record R Axis value (R90). 
               
               
                   
                 F. 
                 Spin to 270°; record R Axis value (R270). 
               
               
                   
                 G. 
                 Calculate Rtarget = (R90 + R270)/2 (the result should 
               
               
                   
                   
                 be the same as step C or the center of the vessel is not 
               
               
                   
                   
                 round. 
               
             
          
           
               
                 5 
                 Verify 
               
               
                   
                 Spin 360° to verify Z and Center indicators move less than 100 
               
               
                   
                 counts. If either is greater than 100 then iterate starting at 
               
               
                   
                 step 3. 
               
               
                   
               
             
          
         
       
     
         [0023]    Thus, novel apparatus and methods have been shown and described. Various changes and substitutions may of course be made without departing from the spirit and scope of the invention. The invention, therefore, should not be limited except by the following claims and their equivalents.