Abstract:
A semiconductor integrated circuit device, and method of manufacturing the same, having a conventional-type lead frame with the die paddle removed. In particular, the die paddle is replaced with a section of tape that is supported by the ends of the lead fingers. The semiconductor die is attached to the tape so that it may be wire bonded to the lead fingers. The tape contains at least one slot to allow for expansion and/or contraction of the tape due to various temperatures experienced during the manufacturing process so that the tape does not wrinkle or warp to alter the position of the die.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of application Ser. No. 09/820,999, filed Mar. 29, 2001, pending, which is a continuation of application Ser. No. 09/537,134, filed Mar. 29, 2000, now U.S. Pat. No. 6,215,177, issued Apr. 10, 2001, which is a continuation of application Ser. No. 09/038,858, filed Mar. 11, 1998, now U.S. Pat. No. 6,091,133, issued on Jul. 18, 2000, which is a continuation of application Ser. No. 08/618,359, filed Mar. 19, 1996, now U.S. Pat. No. 5,729,049, issued Mar. 17, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to semiconductor integrated circuit (IC) devices, and, more specifically, to a method and apparatus for a semiconductor device utilizing a conventional-type lead frame with no die paddle and having a section of tape to support the semiconductor die.  
           [0004]    2. State of the Art  
           [0005]    The semiconductor industry has become one of the most competitive industries in the world. It is thus essential for manufacturers to minimize the per unit production cost while simultaneously increasing the number of units manufactured. Because of the high volume of manufactured products associated with semiconductor fabrication, small changes in production throughput times per semiconductor device can make dramatic changes in the number of devices produced. Moreover, decreasing the number of defective devices produced, even by a small amount, can have a similar dramatic effect on the overall production rate.  
           [0006]    One method of semiconductor device construction that has been recognized is to use an adhering member to retain the lead fingers of a lead frame having a semiconductor support therewith during the wire bonding operation of leads between the semiconductor device and each lead finger. Such methods and semiconductor devices are illustrated in U.S. Pat. Nos. 4,835,120, 4,891,687, 5,227,662, 5,352,633, and 5,475,918.  
           [0007]    Another method of semiconductor device construction that has been recognized is the lead-over-chip (LOC) configuration. In this configuration, the lead frame has no semiconductor paddle support as a part thereof. Rather, the semiconductor device is supported in relation to the lead frame and its lead fingers by means of adhesive tape securing the semiconductor device to the lead fingers overlaying the semiconductor device during wire bonding and other operations. Typical LOC type methods and semiconductor devices are illustrated in U.S. Pat. Nos. 4,862,245, 5,252,853, 5,304,842, and 5,471,369.  
           [0008]    The manufacturing advantages of having a paddleless, conventional-type lead frame have also been recognized in the art. For example, as illustrated in U.S. Pat. No. 5,140,404, assigned to the assignee of the present invention, the die paddle is replaced with tape. The tape is attached to the underside of the lead fingers and extends over the portion of the lead frame where the die paddle would normally be located. The tape serves at least two functions. First, it provides a platform to support the semiconductor die, and second, it stabilizes the ends of the lead fingers during the wire bonding operation. Moreover, because the tape is attached to one side of the lead frame, it provides substantially the same downset to lower the die relative to the top surface of the lead fingers. Thus, the semiconductor die is attached to and supported by the tape during wire bonding of the contacts of the die to the lead fingers.  
           [0009]    However, rather than use thermosetting adhesives to attach the lead fingers of the lead frame to the tape and the semiconductor, as in the process illustrated in the &#39;404 patent, one or more thermoplastic layers are applied to a tape which is subsequently used to support the semiconductor device in a conventional-type lead frame having no semiconductor support paddle therewith. The lead fingers of the lead frame are bonded to the semiconductor device during the wire bonding operation. Use of one or more thermoplastic layers on a tape to support the semiconductor device as well as lock the lead fingers of the lead frame in place is used in place of typical adhesives which require subsequent oven curing steps, such use of thermoplastic layers requires the substantially simultaneous bonding of both the semiconductor device and the lead fingers of the lead frame to the tape while the thermoplastic remains in its soft state. Furthermore, since the thermoplastic typically melts at 100 degrees Centigrade and the wire bonding of the lead fingers to the semiconductor device occurs when both are heated to approximately 250 degrees Centigrade, the thermoplastic may soften during the wire bonding process, thereby allowing the semiconductor device and/or lead fingers to move, causing bonding problems.  
           [0010]    When the lead frame is being manufactured, if the lead fingers of a lead frame have been locked in place through the use of thermosetting types of adhesives, rather than thermoplastic types of adhesive as described in the &#39;404 patent, subsequently, it is easier to use a thermosetting type of adhesive to attach the semiconductor device on the tape in the paddleless lead frame as conventional semiconductor processing is capable of such adhesive use and curing without modification to the fabrication process.  
           [0011]    From the foregoing, it has been recognized in the art to increase chip production efficiency while simultaneously decreasing the number of defective products, it is desirable to utilize a conventional-type lead frame without a die paddle and use tape to retain the chip in the lead frame as well as to retain the lead fingers of the lead frame during wire bonding operations.  
           [0012]    In a conventional-type lead frame, the lead fingers, which form the leads of the packaged semiconductor device, inwardly extend toward the center of the lead frame. A die paddle is positioned proximate the tips or proximal ends of the lead fingers and is generally rectangular in shape. The die paddle provides a relatively stable base to mount the semiconductor die and keep the semiconductor die in place during various manufacturing operations where die alignment is crucial, such as wire bonding.  
           [0013]    The die paddle is typically positioned on a lower plane than the plane defined by the lead fingers such that when the semiconductor die is attached to the die paddle in this configuration, the lowered die paddle decreases the angle and length of wire necessary to wire bond the contacts of the semiconductor die to the ends of the lead fingers. Having the die paddle on a lower plane is more difficult to manufacture and may create various handling problems during the manufacturing process. For example, modified or alternate fixtures for handling lead frames with a lowered die paddle, as opposed to lead frames where the die paddle is not lowered, may be necessary. Additionally, the ends of the lead fingers that are wire bonded are typically plated with gold or silver. Plating part of the die paddle is also necessary if a down bond is needed to secure the semiconductor die to the die paddle.  
           [0014]    During the wire bonding operation, the lead frame, along with its attached die, is typically placed on a heating block to heat the lead frame and die to a specific temperature. Typically, the heating block heats the semiconductor device to approximately 250 degrees Centigrade. Accordingly, any type of tape used to support the die to the lead frame, as previously discussed, must be capable of withstanding temperatures of approximately 250 degrees Centigrade without melting and/or distorting from expansion. If the tape does warp or wrinkle from the heat, the semiconductor die may move relative to the lead fingers and/or the lead fingers may move relative to the semiconductor die. Any such movement may cause misalignment of the lead fingers in relation to the die contacts during the wire bonding operation, resulting in improper wire bonding and production of a defective semiconductor device. Moreover, if the wire bonding operation successfully wire bonds each of the die contacts to the lead fingers, cooling of warped or wrinkled tape may cause the die to pull apart the wire bonds. Thus, it would be advantageous to provide a tape supported lead frame for die attachment that also addresses the effects of expansion and/or contraction of the tape used to support the semiconductor die. It would also be advantageous to provide a tape supported lead frame for die attachment that further addresses the effects of attaching the die through the use of thermosetting adhesives, rather than thermoplastic adhesives which are soft when the die is attached or may soften during the wire bonding process, thereby allowing the die or lead fingers to move with respect to each other.  
         SUMMARY OF THE INVENTION  
         [0015]    According to the present invention, a conventional-type, paddleless lead frame is provided having at least one piece of tape extending to and between the lead fingers where a die paddle would normally lie in a conventional-type lead frame. The tape is of a generally rectangular configuration, but may also be in the form of a circle, oval, parallelogram or any other shape that would fit within the footprint defined by the outside edge of packaging encapsulant. A semiconductor die is then attached to the tape between the proximal ends of the lead fingers using thermosetting types of adhesives. The lead fingers are also attached to the tape through the use of thermosetting types of adhesives.  
           [0016]    In a preferred embodiment, the piece of tape has at least one slot formed therein to allow the tape to expand and contract as it is heated and cooled without moving the semiconductor die attached thereto. Also, the slot permits improved adhesion of the lead fingers and the semiconductor die to the tape during heating and cooling.  
           [0017]    In another preferred embodiment, the die supporting tape includes two transversely extending, substantially parallel slots. The two slots extend along opposite sides of the tape and are proximate the proximal ends of some of the lead fingers. The two slots may also extend along either of the two substantially parallel sides of the tape and may have substantially squared or curved ends.  
           [0018]    In yet another preferred embodiment, the tape includes four slots forming a crossing pattern. The four slots may be substantially parallel to the sides of the tape or extend substantially diagonally across the tape.  
           [0019]    In still another embodiment, the slots are formed from a series of apertures that may be of varying or substantially similar shapes and sizes. For example, each slot may be formed of a row of substantially rectangular or square apertures extending along two or four sides of the tape. Moreover, the apertures may form a grid-like pattern over a substantial portion of the tape.  
           [0020]    In yet another preferred embodiment, the die supporting tape is comprised of at least two pieces of tape with a slot formed by the separating distance between the pieces of tape. Each piece of tape may also have its own opening or slot formed therein to further allow for expansion or contraction of the tape.  
           [0021]    It is believed that a major aspect of the invention is that the tape used to support the die can accommodate a certain amount of expansion and/or contraction from heating or cooling by including an aperture therein without disturbing the alignment of the semiconductor die. This can be accomplished by having an aperture formed into the tape itself or using a number of pieces of tape with openings formed in between the pieces. These, and other features of the present invention, will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a schematic top view of a semiconductor integrated circuit device in accordance with the present invention including a first embodiment of a tape segment;  
         [0023]    [0023]FIG. 2 is a schematic side view of the semiconductor integrated circuit device of FIG. 1;  
         [0024]    [0024]FIG. 3 is a close-up partial top view of the lead fingers and tape configuration of FIG. 1 without an associated semiconductor die;  
         [0025]    [0025]FIG. 4 is a close-up partial top view of a second embodiment of the lead fingers and tape configuration in accordance with the present invention;  
         [0026]    [0026]FIG. 5 is a close-up partial top view of a third embodiment of the lead fingers and tape configuration in accordance with the present invention;  
         [0027]    [0027]FIG. 6 is a close-up partial top view of a fourth embodiment of the lead fingers and tape configuration in accordance with the present invention;  
         [0028]    [0028]FIG. 7 is a close-up partial top view of a fifth embodiment of the lead fingers and tape configuration in accordance with the present invention;  
         [0029]    [0029]FIG. 8 is a close-up partial top view of a sixth embodiment of the lead fingers and tape configuration in accordance with the present invention;  
         [0030]    [0030]FIG. 9 is a close-up partial top view of a seventh embodiment of the lead fingers and tape configuration in accordance with the present invention;  
         [0031]    [0031]FIG. 10 is a close-up partial top view of an eighth embodiment of the lead fingers and tape configuration in accordance with the present invention; and  
         [0032]    [0032]FIG. 11 is a close-up partial top view of a ninth embodiment of the lead fingers and tape configuration in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    Referring to FIG. 1, a semiconductor integrated circuit (IC) device  10  is shown including a portion of a conventional-type lead frame  12 . Typically, the lead frame  12  is part of a lead frame strip comprised of a plurality of lead frames extending from broken edges  13  and  15  and are repeated about the slits  17 . The lead frame  12  includes a plurality of lead fingers  18  that extend toward the center of the lead frame  12 . Each of the lead fingers  18  includes a lead end  20  at a proximal end that is wire bonded to the semiconductor die  14  by wire bond  22 . Typically, the lead ends  20  are plated to achieve a sufficient bond between the wire bond  22  and the lead end  20 . The plated area is generally indicated by dashed line  24 .  
         [0034]    As should be recognized, the lead frame  12  does not include a die paddle for supporting the semiconductor die  14 . Rather, the semiconductor die  14  is supported by tape  16 . As better seen in FIG. 2, the tape  16  is attached to the bottom surface  26  of the lead frame  12  preferably using a thermosetting type of adhesive. When a semiconductor die  14  is subsequently attached to the tape  16 , preferably using a thermosetting type of adhesive, the die  14  sits down inside the lead frame  12 . In this manner, the length of a wire bond  22  between the die  14  and the lead finger  18  is decreased because the top surface  28  of the die  14  is positioned closer to the top surface  30  of the lead frame  12 , as opposed to a die attached to the top surface of a lead frame having a die paddle that is not lowered. The preferred type of adhesive used to bond the lead fingers  18  of the lead frame  12  and the semiconductor die  14  to the tape  16  may be selected from the group of epoxies, acrylics, silicones and polyamides, such adhesives being thermosetting, i.e., capable of irreversibly polymerizing and setting or hardening when heated to some appropriate temperature. Such adhesives are not a thermoplastic; i.e., a material that can be repeatedly melted or softened by heat without a change of properties. When such adhesives are used to bond the lead fingers  18  of the lead frame  12  to the tape  16 , since the adhesive must be cured, typically in an oven, it is necessary to bond the lead fingers  18  to the tape  16  before bonding the semiconductor die  14  to the tape  16 . In this manner, the lead fingers  18  of the lead frame  12  are fixed or locked in position by the tape  16  with the semiconductor die  14  being subsequently locked in position on the tape  16  with respect to the lead fingers  18 . While the lead fingers  18  may engage the tape  16  over any desired length thereof, the tape  16  preferably engages the lead fingers  18  over a length of at least 0.005 inches and may be in excess of 0.060 inches.  
         [0035]    Referring again to FIG. 1, the tape  16  includes two slots  32  and  34  transversely extending across the tape  16  proximate a number of lead ends  20 . As shown, the ends  36  and  38  of the die  14  extend into the slots  32  and  34 , respectively. The slots  32  and  34  may, however, be entirely outside or inside the footprint of the die  14 . Moreover, the slots  32  and  34  are longer than the corresponding width of the die. However, the slots  32  and  34  may be shorter or longer, depending on the size of the die used and/or the desires of the manufacturer.  
         [0036]    As shown in FIG. 3, the slots  32  and  34  may transverse the short side  40  of the tape  16  and have a generally rectangular configuration. Similarly, the slots  42  and  44  shown in FIG. 4 may transverse the long side  46  of the tape  16  and have rounded ends  48 ,  50  and  52 ,  54 , respectively.  
         [0037]    It may, however, not be necessary to incorporate more than one slot in the tape  16  to achieve the necessary give in the tape  16  to allow for expansion and/or contraction of the tape  16 . For example in FIG. 5, a single slot  56  may transverse the tape  16  about the center line  58 . Moreover, as shown in FIG. 6, the slot or opening  60  may actually be formed by spacing apart two tape segments  62  and  64 . In addition, each segment of tape  62  and  64  may each include their own transverse apertures  66  and  68 , respectively, positioned proximate several proximate ends  70  of the lead fingers  18 .  
         [0038]    It may also be desirable to incorporate more than two slots and position the slots so that they are not substantially parallel to one another. For example in FIG. 7, the slots  72 ,  74 ,  76 , and  78  are substantially diagonally positioned across the tape  16  to form an “X” pattern. Likewise, the slots  80 ,  82 ,  84 , and  86  may form a cross-like pattern in the tape  16 , as shown in FIG. 8.  
         [0039]    Referring now to FIG. 9, each slot may be formed from a plurality of apertures  88  positioned to form any of the previously described configurations or any other configuration as desired. In this embodiment, the apertures are configured similar to the embodiment shown in FIG. 3, but may be altered in size, shape, and/or number.  
         [0040]    As shown in FIG. 10, the apertures may include both relatively smaller apertures  90  and larger apertures  92  and may be positioned proximate the perimeter  94  of the tape  16 .  
         [0041]    Finally, as shown in FIG. 11, it may be desirable to form a grid-like pattern of slots or apertures  96  over a substantial portion of the tape  16 . The apertures  96  may be all substantially the same size or varying in size as illustrated.  
         [0042]    In the exemplary embodiments, the tape as illustrated has a generally rectangular configuration, and the illustrated slot configurations are generally symmetrical about one lead frame axis or another. Those skilled in the art, however, will appreciate that the size and/or shape of the tape may vary and the slots may equally be asymmetrically positioned about the tape without departing from the spirit of the present invention. It will also be appreciated by one of ordinary skill in the art that one or more features of the illustrated embodiments may be combined with one or more features from another to form yet another combination within the scope of the invention as described and claimed herein. Thus, while certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the invention disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims. For example, various slot configurations may be utilized; the number of apertures may be increased or decreased; and the number of tape segments may be varied.