Abstract:
A tool and method is provided for repositioning a solder injection head. The tool includes a first moveable platform positioned on a first side of a workpiece chuck and a second moveable platform positioned on a second side of the workpiece chuck. A solder injection head has a seal configured to seal molten solder within the solder injection head when contacting a surface of the first moveable platform or the second moveable platform. The method includes moving a workpiece chuck and a starting platform to a position such that the starting platform is at a finishing position and a finishing platform is in a starting position.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a tool used in the fabrication of semiconductor devices and methods of use and, more specifically, to a tool used to reposition a solder injection head and methods of use. 
       BACKGROUND OF THE INVENTION 
       [0002]    Controlled Collapse Chip Connection New Process (C4NP) represents a breakthrough in wafer solder bump technology, a semiconductor packaging technique which places pre-patterned solder balls onto the surface of a chip. These bumps ultimately carry data from individual chips to the rest of a computing system via a complex arrangement of intricate wiring and materials. C4NP is built around International Business Machines Corp.&#39;s development of injection-molded solder. 
         [0003]    In C4NP, molten solder is injected into cavities in a mold which are designed to match the wafer pads. C4NP allows the creation of pre-patterned solder balls to be completed while a wafer is still in the front-end of a manufacturing facility, The separate operations, e.g., bump formation and wafer processing, provides many advantages. For example, the formation of the solder bumps in the mold reduces the handling of fully processed wafers. This increases wafer yield as there is less likelihood of wafer damage or breakage. The separate processes also isolate the wafers from the yield losses due to failures in on-wafer bump formation. Also, the wafers and bumps can be processed in parallel, compared to serially, which effectively shortens line throughput time. Said otherwise, bump molding can be completed while the wafers are still in process potentially reducing cycle time significantly. Also, amongst other advantages, final assembly yield increases because bumps are inspected prior to transfer onto to the wafer. In this way, the bumps can be reworked as needed. 
         [0004]    C4NP also easily accommodates binary, ternary and quaternary alloys and minimizes the recurring and additive costs of consumables since only the solder balls are created and transferred to the wafer without waste. The solder can also come in any form such as, wires or pellets, which are less expensive than plating solutions, preforms, or pastes. C4NP is also not dependent on wafer size, allowing 200 mm and 300 mm wafers to be processed with similar efficiency. 
         [0005]    In current processing techniques, the method of injecting the solder allows travel of the mold relative to the injection head in a single direction. In order to cyclically process molds in current tools, there is a requirement to reposition the head from an end of process (finish) position to a beginning of process (start) position. This means having to process, e.g., fill, molds in a serial, batch process, as the injection head remains stationary. 
         [0006]    Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove. 
       SUMMARY OF THE INVENTION 
       [0007]    In a first aspect of the invention, a tool comprises a first moveable platform positioned on a first side of a workpiece chuck and a second moveable platform positioned on a second side of the workpiece chuck. A solder injection head has a seal configured to seal molten solder within the solder injection head when contacting a surface of the first moveable platform or the second moveable platform. 
         [0008]    In an additional aspect of the invention, a tool comprises a workpiece chuck moveable in a horizontal direction and stationary in a vertical direction. A first moveable platform is positioned on a first side of the workpiece chuck and is independently moveable in the horizontal direction and the vertical direction. A second moveable platform is positioned on a second side of the workpiece chuck and is independently moveable in the horizontal direction and the vertical direction. A solder injection head has a seal configured to seal molten solder within the solder injection head when contacting a surface of either the first moveable platform or the second moveable platform. The solder injection head is configured to move in the vertical direction when positioned on one of the first moveable platform and the second moveable platform and remain stationary in the horizontal direction. 
         [0009]    In a further aspect of the invention, a method of injecting solder into molds comprises moving a workpiece chuck and a starting platform to a position such that the starting platform is at a finishing position and a finishing platform is in a starting position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention is described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention. 
           [0011]      FIG. 1  shows a tool structured and configured to reposition a solder injection head in accordance with the invention; and 
           [0012]      FIGS. 2   a - 2   p  show operational stages of the tool shown in  FIG. 1  in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The present invention generally relates to a tool used in the fabrication of semiconductor devices and methods of use and, more specifically, to a tool used to reposition a solder injection head and methods of use. By implementing the invention, it is possible to provide many advantages over known tools. For example, the present invention ensures that a proper seal is always maintained between a solder injection head and an underlying surface, thereby ensuring that the solder can be maintained in a molten state and remains within the solder injection head when not in use. Also, in implementation, the tool of the present invention eliminates the need for batch processing of the molds; instead, due to the flexibility of the tool it is now possible to process molds individually as needed. Additionally, as the solder injection head is always injecting solder in a single direction during mold fill, a consistent and constant load is always placed on the solder injection head (as the leading and trailing edges are always the same for each mold). This constant load, in turn, leads to predictability when filling the cavities of the solder mold, as well as ensures prevention of solder leakage. Also, as the leading and trailing edge always remain the same throughout mold fills, there is no oxide build-up on the leading edge which, in turn, provides a better quality solder. 
         [0014]    In embodiments, the tool includes two lifting assemblies or “parking spaces” that are used in conjunction with the solder injection head to ensure a proper seal. The proper seal, in turn, prevents leakage and exposure to air thus reducing oxide build-up. The design of the parking spaces is such that they can be lifted in concert with the solder injection head to continue the leak and exposure prevention while allowing motion of the workpiece relative to these spaces. 
       Tool in Accordance with Embodiments of the Invention 
       [0015]      FIG. 1  shows a tool structured and configured to reposition a solder injection head in accordance with the invention. More specifically, the tool of the present invention is generally shown at reference numeral  10  and includes two moveable platforms (“parking spaces”)  12   a ,  12   b , positioned on opposing sides of a workpiece chuck  14 . The moveable platforms  12   a ,  12   b  and the workpiece chuck  14  are mounted to a moveable carriage having a rail and bearing system, generally depicted as reference numeral  16 . In embodiments, the moveable platforms  12   a ,  12   b  can be raised or lowered in the z direction using conventional air cylinders  18   a  and  18   b , or other known mechanisms (e.g., actuators). In embodiments, the lifting mechanisms are provided to lift and lower the moveable platforms  12   a ,  12   b  when they are at different locations in the x direction. Also, the moveable platforms  12   a ,  12   b  can be independently moved in the x direction using conventional mechanisms  19 , e.g., linear actuators, air cylinders, etc. 
         [0016]    As shown in  FIG. 1 , a solder injection head  20  is positioned on the moveable platform  12   a ; however, it is understood that the solder injection head  20  can be positioned on the moveable platform  12   a , over the workpiece chuck  14  or on moveable platform  12   b  (See,  FIGS. 2   a - 2   p ). The solder injection head  20  includes a seal  20   a , e.g., o-ring, that contacts the upper surface of the moveable platforms  12   a ,  12   b  and a workpiece, W, positioned on the workpiece chuck  14 . (Those of skill should understand that the workpiece is a mold with a plurality of cavities for solder fill.) The seal  20   a  prevents leakage of solder from the solder injection head  20  when it is positioned on the surface of the moveable platforms  12   a ,  12   b.    
         [0017]    An air cylinder  22  or other mechanism (e.g., a spring) is positioned above the solder injection head  20 , at an opposing side to the seal  20   a . The mechanism  22  is configured to provide a regulated downward force on the solder injection head  20 . This ensures an adequate (i.e., leak proof) seal between the seal  20   a  and a surface of the moveable platforms  12   a ,  12   b  or the workpiece, W. In one embodiment, the force is about 100 lbs; however, it should be recognized that any appropriate force to ensure an adequate seal is contemplated by the invention. Considerations to take into account when engineering the force include, for example, the viscosity of the solder, the type of material used for the seal, how large is the seal or solder injection head, etc. 
         [0018]    As noted above, the moveable platforms  12   a ,  12   b  can be raised or lowered in the z direction using conventional air cylinders  18   a  and  18   b  or other known mechanisms. In embodiments, the moveable platforms  12   a ,  12   b  can be raised or lowered in the z direction when in certain x positions, e.g., aligned with one of the air cylinders  18   a  and  18   b . In embodiments, the moveable platforms  12   a ,  12   b  are configured to be raised to a height above the workpiece, e.g., one or more inches. This ensures that the workpiece does not interfere with the movement of the moveable platforms in the x direction. 
         [0019]    In operation, the moveable platforms  12   a ,  12   b  can move independent of each other as well as independent of the solder injection head  20 . Also, the moveable platforms  12   a ,  12   b  can move independent or concurrently with the workpiece chuck  14 . In preferred embodiments, the moveable platforms  12   a ,  12   b  can be raised or lowered when underneath the solder injection head  20 . However, it should be understood that the moveable platforms  12   a ,  12   b  can be moved independent of the solder injection head  20  (when it is in its lifting position that is not under the solder injection head  20 ). 
         [0020]    The workpiece chuck  14  is fixed in the z direction and can be moved left or right in the x direction via a carriage on the rail and bearing system or other conventional system generally depicted as reference numeral  16 . Likewise, the moveable platforms  12   a ,  12   b  are also moveable in the x direction via the carriage  16 . In one embodiment, the moveable platforms  12   a ,  12   b  are held onto bases, via a vacuum system, which is mounted on carriage  16 . The air cylinders  18   a  and  18   b  are configured to lift the moveable platforms  12   a ,  12   b  from their base. 
         [0021]    In embodiments, the solder injection head  20  is fixed in the x direction, and can be raised or lowered in the z direction via the moveable platforms  12   a ,  12   b . In an alternative embodiment, the solder injection head  20  can also be moved in the x direction, depending on a particular application. As discussed in further detail below, when the solder injection head  20  is raised or lowered, the seal  20   a  remains in contact with either surface of the moveable platforms  12   a ,  12   b , thereby preventing any leakage of solder. Also, the sealing of the solder within the solder injection head will allow the solder to remain in a molten state during transportation and when not in use. 
         [0022]      FIGS. 2   a - 2   p  show operational stages of the tool of  FIG. 1  in accordance with the invention. For ease of illustration, the carriage  16  shown in  FIG. 1  is removed in order to more clearly show the different operational stages of the invention. However, it should be recognized by those of skill in the art that the workpiece chuck  14  and the moveable platforms  12   a ,  12   b  can be concurrently moved in the x direction via the carriage  16  during solder flow processes and the “swap” of platforms, as discussed in greater detail below. Also, one or more of the lifting mechanisms  18   a  and  18   b  may be removed in some of the illustrations to more clearly show operational stages which do not require the mechanisms  18   a  and  18   b.    
         [0023]      FIG. 2   a  shows a starting position of the tool  10 . In this position, the solder injection head  20  is positioned on the moveable platform  12   a  with a force such that the seal  20   a  prevents leakage of the solder. The moveable platform  12   a  and the moveable platform  12   b  are positioned away form the workpiece chuck  14 . This allows a wafer to be placed on the workpiece chuck  14  without any interference. At this operational stage, the workpiece is not placed on the workpiece chuck  14 . The moveable platform  12   a  may be in alignment with the lifting mechanism  18   a  but this is not yet a requirement. 
         [0024]    In  FIG. 2   b , the workpiece, W, is loaded on the workpiece chuck  14  in a conventional manner. In  FIG. 2   c , the moveable platform  12   b  is moved independently of the workpiece chuck  14  in the x direction by an actuator  19 , toward the workpiece W. The moveable platform  12   b  will stop when it is in contact with the workpiece W. This contact can be detected by, for example, any conventional type sensor, e.g., physical contact sensor, or by a known distance of travel. 
         [0025]    In  FIG. 2   d , the workpiece chuck  14  and the moveable platform  12   b  are moved together toward the solder injection head  20  and moveable platform  12   a , while the solder injection head  20  remains stationary and the moveable platform  12   a  (start parking space) is held in place by friction with the seal  20   a . This motion is continued until after contact is made between the workpiece and the moveable platform  12   a , at which point the friction between the seal  20   a  and the surface of the moveable platform  12   a  is overcome. The movement of the workpiece chuck  14  and the moveable platform  12   b  is provided by the carriage (not shown). 
         [0026]      FIG. 2   e  shows the workpiece, W moved under the solder injection head  20 . More specifically, in  FIG. 2   e , the workpiece chuck  14 , workpiece and the moveable platforms  12   a ,  12   b  are moved concurrently in the x direction (towards the right) by the carriage, while the solder injection head  20  remains stationary. In this manner, solder can be injected into cavities of the workpiece W. Also, as the relative movement of the solder injection head  20  is always in a single direction during mold fill, the leading edge and trailing edge always remain constant throughout mold fills. This ensures a constant, predictable load on the seal, as well as eliminates oxide build-up on the leading edge of the solder injection head  20 . For illustrative purposes, lifting mechanisms  18   a  and  18   b  are shown to illustrate a relative movement of the assembly with respect to the lifting mechanisms  18   a  and  18   b.    
         [0027]    As shown in  FIG. 2   f , the movement of the assembly stops when the solder injection head  20  rests on the moveable platform  12   b  (finish parking space). As should be understood by those of skill in the art, a constant force remains on the solder injection head  20  (during the entire process) to ensure that the seal is properly sealed against a surface of the moveable platform  12   b  thereby preventing leakage of the solder. In this position, the moveable platform  12   b  is also aligned or substantially aligned with the mechanism  18   a  (which was originally near the moveable platform  12   a  prior to solder injection, e.g., movement of the assembly). 
         [0028]    In  FIG. 2   g , the moveable platform  12   b  (finish parking space) is separated from the workpiece, W. In this position, the moveable platform  12   b  is aligned with the lifting mechanism  18   a . The friction from the seal  20   a  holds the moveable platform  12  to the solder injection head  20  as the moveable platform  12   a  is moved in the x direction, away from the workpiece chuck  14 . 
         [0029]    In  FIG. 2   h , the moveable platform  12   a  is moved away (separated) from the workpiece, W, by the actuator  19 . This provides clearance between the moveable platforms  12   a ,  12   b  and the workpiece, W, so that the workpiece can be removed. 
         [0030]    In  FIG. 2   i , the moveable platform  12   b  and the solder injection head  20  are lifted, e.g., by the air cylinder  18   a , so that the bottom of the moveable platform  12   b  is above a top plane of the workpiece, W. In  FIG. 2   j , the workpiece chuck  14  and the workpiece, W, as well as the moveable platform  12   a  are moved together under the moveable platform  12   b  and solder injection head  20  to an x location, e.g., moved until the moveable platform  12   a  is aligned with another air cylinder  18   b  (or other type of lifting mechanism such as, for example, an actuator). The movement of these components can be accomplished by the carriage (not shown in order to simplify the illustration of  FIG. 2   j ). In  FIG. 2   k , the moveable platform  12   a  is independently lifted by the mechanism (e.g., air cylinder  18   b ) to a height where the bottom of the moveable platform  12   a  is above a top plane of the workpiece, W. 
         [0031]    In  FIG. 2   l , the workpiece chuck  14  is moved under the moveable platform  12   a  to a point where the moveable platform  12   a  can now be in the original position of the moveable platform  12   b  (e.g., to the left of the workpiece chuck  14 ). In  FIG. 2   m , the moveable platform  12   a  is lowered to a height which would be planar with the workpiece, W, e.g., original height. In  FIG. 2   n , the workpiece chuck  14  and the moveable platform  12   a  are moved under the lifted solder injection head  20  and the moveable platform  12   b  until the moveable platform is aligned with the lifting mechanism  18   a . This movement in the x direction is provided by the carriage. In this way, the moveable platform  12   b  (with the solder injection head) is now positioned in the original position of the moveable platform  12   a , e.g., to the right of the workpiece chuck  14 . 
         [0032]    In  FIG. 2   o , the solder injection head  20  and the moveable platform  12   b  are lowered into the original position of the moveable platform  12   a , e.g., to the right of the workpiece chuck  14 . The moveable platforms  12   a ,  12   b  are now swapped and ready for a next workpiece. In  FIG. 2   p , the workpiece W is removed. In embodiments, the operational stages of  FIGS. 2   a - 2   p  can be repeated. 
         [0033]    The methods as described above are used in the fabrication of integrated circuit chips. The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor. 
         [0034]    While the invention has been described in terms of embodiments, those of skill in the art will recognize that the invention can be practiced with modifications and in the spirit and scope of the appended claims.