Abstract:
An integrated circuit includes peripheral conductive pads interconnected by a peripheral conductive track within an integrated circuit chip. The integrated circuit chip further includes internal conductive pads interconnected by an internal conductive track within the integrated circuit chip. A conductive bonding wire external to the integrated circuit chip connects the one peripheral conductive pad to one internal conductive pad. A package encapsulates the integrated circuit chip and the conductive bonding wire.

Description:
PRIORITY CLAIM 
       [0001]    This application claims the priority benefit of French Application for Patent No. 1561095, filed on Nov. 18, 2015, the disclosure of which is hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure generally relates to electronic circuits and, more particularly, to the distribution of potentials for powering an integrated circuit. 
       BACKGROUND 
       [0003]    Integrated circuits are generally assembled in a package and are connected to other circuits and to power supply terminals. The distribution of the power supply potentials or of static signals in an integrated circuit from external connection terminals is a recurring problem. 
         [0004]    Most often, terminals of connection of the package to another package or to an electronic board are distributed at the periphery of the package containing the semiconductor material chip. Connecting one of these pads to a terminal for providing a static potential is generally insufficient to preserve homogeneity of the potential within the chip. Indeed, the tracks conveying this static potential from the external terminal all the way to the elements using them have parasitic resistances which generate potential drops. 
         [0005]    One thus generally has to use a plurality of regularly distributed terminals of the package, which are connected to different pads of the integrated circuit internal to the package. A sort of ring is thus created around the integrated circuit to distribute the static potentials, particularly the power supply potentials. The higher the number of terminals delivering the potential, the better the distribution, that is, the smaller the power supply voltage intervals between the different points (pads) of the integrated circuit. However, the higher the number of terminals, the greater the package bulk. 
       SUMMARY 
       [0006]    It would be desirable to decrease the number of terminals of connection of a package to static potentials without adversely affecting the distribution of these potentials in a circuit integrated in the package. 
         [0007]    An embodiment overcomes all or part of the disadvantages of usual packages and of the distribution of a same static potential. 
         [0008]    An embodiment provides a solution more particularly adapted to integrated circuits equipped with peripheral power supply rails. 
         [0009]    An embodiment provides a solution which is easy to implement. 
         [0010]    Thus, an embodiment provides an integrated circuit comprising: at least two peripheral conductive pads interconnected by a peripheral conductive track; and at least one conductive wire connecting the two conductive pads. 
         [0011]    According to an embodiment, the circuit comprises: a first number of first peripheral conductive pads, interconnected by at least one first peripheral track; a second number of second conductive pads arranged close to the center of the chip, interconnected by at least one second conductive track; and conductive wires connecting two by two a first pad and a second pad. 
         [0012]    According to an embodiment, the first and second numbers are equal. 
         [0013]    According to an embodiment, the first and second conductive tracks are in different conductive levels. 
         [0014]    According to an embodiment, the circuit further comprises: a third number of first peripheral conductive pads, interconnected by at least one third peripheral track; a fourth number of second pads arranged close to the center of the chip, interconnected by at least one fourth conductive track; and conductive wires connecting two by two a third pad and a fourth pad. 
         [0015]    According to an embodiment, the third and fourth numbers are equal. 
         [0016]    According to an embodiment, the third and fourth conductive tracks are in different conductive levels. 
         [0017]    According to an embodiment, the first, second, third, and fourth numbers are equal. 
         [0018]    According to an embodiment, said wires are made of copper or of gold. 
         [0019]    An embodiment also provides an electronic circuit comprising: an integrated circuit such as hereabove; and a package comprising a first terminal connected by a conductive wire to only one of the peripheral pads of the circuit. 
         [0020]    According to an embodiment, a second terminal is connected by a conductive wire to only one of the third pads of the integrated circuit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The foregoing and other features and advantages will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings. 
           [0022]      FIG. 1  schematically shows a usual embodiment of a connection of terminals of a package to pads of an integrated circuit contained in the package; 
           [0023]      FIG. 2  schematically shows an embodiment of a connection of terminals of a package to pads of an integrated circuit contained in the package; 
           [0024]      FIG. 3  schematically illustrates connections to the center of the integrated circuit in the embodiment of  FIG. 2 ; and 
           [0025]      FIG. 4  schematically shows another embodiment of a connection of terminals of a package to pads of an integrated circuit contained in the package. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    The same elements have been designated with the same reference numerals in the different drawings. In particular, the structural and/or functional elements common to the different embodiments may be designated with the same reference numerals and may have identical structural, dimensional, and material properties. For clarity, only those steps and elements which are useful to the understanding of the described embodiments have been shown and will be detailed. In particular, the destination of the static potentials, be it inside or outside of the circuit, has not been detailed, the described embodiments being compatible with current uses of such potentials. Further, the structures and functions of the integrated circuit have not been detailed either, the described embodiments being here again compatible with usual integrated circuit structures and functions. When reference is made to terms “about”, “approximately”, or “in the order of”, this means to within 10%, preferably to within 5%. For simplification, only the connections of static power supply potentials will be described hereafter, since the other connections of signals processed by the integrated circuit are not modified by the implementation of the described embodiments. 
         [0027]      FIG. 1  schematically shows an example of an integrated circuit in a package. 
         [0028]    An integrated circuit chip  2  comprises a plurality of pads  22  and  24  distributed at the chip periphery and interconnected by peripheral rails  26  and  28 . To homogeneously distribute the power supply potentials in rails  26  and  28 , pads  22  and  24  are individually connected to terminals of connection of a package  3  which are, outside of the package, connected to the corresponding power supply potentials. Due to peripheral rails  26  and  28  at the level of chip  2 , it is indeed usual to provide a plurality of external connections to limit the influence of the parasitic resistances of the rail conductors. However, this considerably increases the number of terminals  32  and  34  of package  3 . 
         [0029]    According to the embodiments which will be described, it is provided to distribute the power supply potentials (more generally, static potentials used in a plurality of areas of the integrated circuit) from the center of the integrated circuit chip. 
         [0030]      FIG. 2  is a simplified representation of an embodiment of a packaged integrated circuit. 
         [0031]    An integrated circuit chip  4  is integrated in a package  5  comprising terminals  52  and  54  of connection to the outside. In the same way as for  FIG. 1 , for simplification, only the connections to power supply potentials are shown. 
         [0032]    As compared with the  FIG. 1  implementations, the package  5  comprises a single terminal  52  or  54  per power supply potential. Even if this does not appear from the drawings, which are not to scale, this enables either to decrease the package size, and thus the general bulk, or to make terminals of connection to the outside available to integrate other functions. To preserve homogeneous distribution of the power supply potentials, the chip still comprises a plurality of pads  42  and  44 , preferably regularly distributed, connected to peripheral rails  46  and  48  of distribution of the power supply potentials. 
         [0033]    It is provided to distribute the power supply potentials originating from terminals  52  and  54  from the center of chip  4  and no longer from the periphery thereof. As appears from the following description, differences in electric path length are thus decreased, which homogenizes the access resistances, and thus the distribution of the potentials at the level of chip  4 . 
         [0034]    In the shown example, at the center of chip  4 , as many pads  62  and  64  (in the example, four pads  62  and four pads  64 ) as there exist pads  42  and  44  are provided. Pads  62  and  64  are, like pads  42  and  44 , provided at the upper surface of the chip. Each pad  42 , respectively  44 , is connected by a wire  66 , respectively  68 , external to chip  4 , to a pad  62 , respectively  64 . Thus, while there conventionally is a tendency to form all the connections with conductive tracks integrated to the chip, the inventors here provide forming the static potential connections from the outside of the chip. 
         [0035]    Pads  52  and  54  are respectively connected, by conductive wires  56 , respectively  58 , to one (and only one) of pads  42 , respectively  44 , of the periphery of chip  4 . 
         [0036]    To allow the distribution of a plurality of static potentials and avoid wire crossings which would risk generating a short-circuit, pads  62  (or  64 ) are connected to one another, by nature of pads, by conductive tracks integrated to the chip. For example, the tracks are formed in the same metallization levels as peripheral tracks  46  and  48 . 
         [0037]      FIG. 3  is a simplified representation illustrating the forming of interconnections of pads  62  with one another and of pads  64  with one another. In this example, conductive tracks, respectively  65  and  67 , connecting pads  62  together and, separately, pads  64  together, in two different conductive levels of chip  4 , are provided. 
         [0038]    The above-described embodiment takes advantage from the better conductivity of bonding wires, for example, made of gold or of copper, as compared with integrated conductive tracks. The distribution from the center of the chip further enables to homogenize the distributed potentials. 
         [0039]    The larger the number of pads  42  and  44 , and thus  62  and  64 , of the chip, the better the power supply potential distribution. 
         [0040]    Once the wire bondings have been performed, the assembly is encapsulated in an insulating resin forming the package. Conductive wires  56 ,  58 ,  66 , and  68  are thus all integrated in package  5 . 
         [0041]      FIG. 4  is a top view of another embodiment enabling, without optimizing the distribution as in the embodiment of  FIGS. 2 and 3 , to however improve it with respect to current solutions. 
         [0042]    In this example, the case of an integrated circuit  4 ′ equipped with peripheral power supply potential distribution rails (not shown) in the same way as in  FIG. 2  is considered. Circuit  4 ′ comprises two approximately diametrically opposite peripheral pads  42 ′ and two approximately diametrically opposite peripheral pads  44 ′ (considering a circle within which the circuit is inscribed). 
         [0043]    In the same way as in  FIG. 2 , two terminals  52  and  54  of the package are connected by wires to two peripheral pads  42 ″ and  44 ″ of the circuit. Pads  42 ″ and  44 ″ are connected by conductive tracks, not shown, to the peripheral power supply rails. 
         [0044]    According to the embodiment of  FIG. 4 , conductive wires  66 ′ and  68 ′ connecting pads  42 ′ and pads  44 ′ two by two are provided. Thus, even with a single input point (pads  42 ″ and  44 ″) for the power supply potentials, the potential distribution is homogenized with respect to the simple peripheral rail while the number of terminals of the package is decreased. 
         [0045]    Various embodiments have been described. Various alterations, modifications, and improvements will occur to those skilled in the art. In particular, the number of pads  42  and  44  may vary according to the applications. Further, the number of potentials to be distributed also varies according to the application. Further, the practical implementation of the embodiments which have been described is within the abilities of those skilled in the art based on the functional indications given hereabove. 
         [0046]    Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and the scope of the present invention. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The present invention is limited only as defined in the following claims and the equivalents thereto.