Patent Publication Number: US-11380612-B2

Title: Semiconductor device, electronic component and method

Description:
BACKGROUND 
     In some applications, two or more electric circuits communicate, for example, by bidirectional signal exchange. If the electric circuits have a ground at different potentials, galvanic isolation may be used to prevent current flow between the electric circuits whilst permitting communication between the electric circuits. Galvanic isolation may be based on optical, capacitive or inductive communication for example. An example of a device for inductive galvanic isolation and signal exchange is a coreless transformer which includes a primary winding and a secondary winding separated by an isolation layer that is sufficiently thin to allow bidirectional transmission of signals. 
     In some applications in which electric power and information are transferred from a higher-voltage network, such as the grid, to a lower-voltage network, such as a domestic power supply network, reinforced galvanic isolation against spikes of up to 10 kV or higher is desirable, if not required by regulatory authorities. 
     SUMMARY 
     In an embodiment, a semiconductor device includes a galvanically isolated signal transfer coupler including a contact pad. The contact pad includes a metallic base layer, a metallic diffusion barrier layer arranged on the metallic base layer, and a metallic wire bondable layer arranged on the metallic diffusion barrier layer. The metallic diffusion barrier layer includes a first portion and a second portion. The first portion has a first surface including a curved surface at the periphery and a second surface opposing the first surface. The first portion extends in a transverse plane and has a width. The second portion protrudes from the second surface intermediate the width of the first portion. 
     In some embodiments, the semiconductor device further includes a first isolation layer arranged on peripheral regions of the metallic base layer and having a first opening exposing a portion of the metallic base layer, wherein the second portion of the metallic diffusion barrier layer is arranged in the first opening in the first isolation layer and the first portion of the metallic diffusion barrier layer extends onto a surface of the first isolation layer adjacent the first opening. 
     In some embodiments, the semiconductor device further includes a metallic passivation layer on the metallic wire bondable layer. 
     In some embodiments, the metallic base layer includes copper, and/or the metallic diffusion barrier layer includes NiP, and/or the metallic wire bondable layer includes Pd and/or the metallic passivation layer includes Au. 
     In some embodiments, the semiconductor device further includes a second isolation layer arranged on peripheral regions of the metallic wire bondable layer and including a second opening exposing a portion of the metallic wire bondable layer. The metallic passivation layer may be arranged in and bounded by the second opening. 
     In some embodiments, the semiconductor device further includes a third isolation layer including a ring arranged on the first isolation layer and a fourth isolation layer arranged on outer faces of the third isolation layer. 
     In some embodiments, the first isolation layer includes hydrogenated Si x N y  and the second isolation layer includes an imide. 
     In some embodiments, the third isolation layer includes SiO x  or phosphosilicate glass and the fourth isolation layer includes hydrogenated Si x N y . 
     In some embodiments, the galvanically isolated signal transfer coupler includes an inductive coupler including a planar coil coupled to the contact pad. 
     In some embodiments, the inductive coupler includes a second planar coil arranged in a stack with the first planar coil and galvanically isolated from the first planar coil by a isolation layer including SiO x  and is configured to provide reinforced galvanic isolation for a surge pulse isolation voltage V IOSM  of at least 10 kV peak . 
     In some embodiments, the semiconductor device further includes a third planar coil that is arranged substantially coplanar with the first planar coil and is coupled to the contact pad. 
     In some embodiments, the planar coil and the metallic base layer are integrated in a semiconductor die. 
     In some embodiments, the galvanically isolated signal transfer coupler includes a capacitive coupler and the contact pad provides a plate of the capacitive coupler. 
     In an embodiment, an electronic component includes the semiconductor device according to any one of the previously described embodiments and a bidirectional signal transfer path coupled to the semiconductor device. A galvanically isolated signal transfer coupler is coupled in the bidirectional signal transfer path and is coupled by a bond wire to the semiconductor device. The galvanically isolated signal transfer coupler provides reinforced galvanic isolation for a surge pulse isolation voltage V IOSM  of at least 10 kV peak . 
     In some embodiments, the electronic component further includes a further semiconductor device being coupled to the semiconductor device by way of the bidirectional signal transfer path. 
     In an embodiment, a method for forming a contact pad includes depositing a metallic diffusion barrier layer onto a surface of a metallic base layer exposed in a first opening of a first isolation layer that covers a peripheral region of the metallic base layer such that the metallic diffusion barrier layer extends onto an outer surface of the first isolation layer. The metallic diffusion barrier layer is annealed and a metallic wire bondable layer is deposited onto the annealed metallic diffusion barrier layer. 
     In some embodiments, the metallic diffusion barrier layer is deposited using electro-chemical deposition or galvanic deposition. 
     In some embodiments, the method further includes depositing a second isolation layer onto peripheral regions of the metallic wire bondable layer defining a second opening exposing a portion of the wire bondable layer. 
     In some embodiments, the method further includes depositing a metallic passivation layer onto the metallic wire bondable layer such that the second isolation layer bounds the metallic passivation layer. 
     In an embodiment, a semiconductor device is provided that includes a galvanically isolated signal transfer coupler including a contact pad. The contact pad includes a metallic base layer and a metallic anchoring layer arranged on the metallic base layer. The metallic anchoring layer includes a first portion and a second portion. The first portion has a first surface and a second surface opposing the first surface. The first surface of the first portion includes a curved surface at the periphery. The first portion extends in a transverse plane and has a width. The second portion protrudes from the second surface intermediate the width of the first portion. 
     In some embodiments, the metallic anchoring layer and/or the metallic base layer includes copper. 
     In some embodiments, the semiconductor device further includes a first isolation layer arranged on peripheral regions of the metallic base layer and having a first opening exposing a portion of the metallic base layer, wherein the second portion of the metallic anchoring layer is arranged in the first opening in the first isolation layer and the first portion of the metallic anchoring layer extends onto a surface of the first isolation layer adjacent the first opening. 
     In some embodiments, the first isolation layer includes SiO x . 
     In some embodiments, the semiconductor device further includes a metallic adhesion promotion layer lining the first opening. In some embodiments, the semiconductor device further includes an insulating passivation layer arranged on the first surface of the metallic anchoring layer. 
     In some embodiments, the insulating passivation layer includes Al 2 O 3  or Si x N y . In some embodiments, the first isolation layer includes Si x N y . 
     In some embodiments, the metallic anchoring layer is in direct contact with the metallic base layer, the side walls of the first opening and surface of the insulating layer adjacent the first opening. 
     In some embodiments, the semiconductor device further includes one or more metallic layers arranged on the metallic anchoring layer. 
     In some embodiments, the one or more further metallic layers include a NiP layer arranged on an outer surface of the anchoring layer, a Pd layer arranged on the NiP layer and a Au layer arranged on the NiP layer. 
     Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. The features of the various illustrated embodiments can be combined unless they exclude each other. Exemplary embodiments are depicted in the drawings and are detailed in the description which follows. 
         FIG. 1 a    illustrates a semiconductor device including a galvanically isolated signal transfer coupler including a contact pad according to an embodiment. 
         FIG. 1 b    illustrates a semiconductor device including a galvanically isolated signal transfer coupler including an inductive coupler including a planar coil and a contact pad according to an embodiment. 
         FIG. 1 c    illustrates a semiconductor device including a galvanically isolated signal transfer coupler including a capacitive coupler including a contact pad according to an embodiment. 
         FIG. 2  illustrates a semiconductor device including an inductive coupler including planar coil and a contact pad according to an embodiment. 
         FIG. 3 a    illustrates a contact pad for an inductive or a capacitive coupler. 
         FIG. 3 b    illustrates an enlarged view of the contact pad of  FIG. 3   a.    
         FIG. 4  illustrates a connection structure for an inductive or a capacitive coupler according to an embodiment. 
         FIG. 5  illustrates a connection structure for an inductive or a capacitive coupler according to an embodiment. 
         FIG. 6 a    illustrates a contact pad for an inductive or a capacitive coupler according to a further embodiment. 
         FIG. 6 b    illustrates a contact pad for an inductive or a capacitive coupler according to a further embodiment. 
         FIG. 7  is a flow chart of a method for fabricating a contact pad for an inductive or a capacitive coupler. 
         FIG. 8 a    illustrates a perspective view of an inductive coupler according to an embodiment. 
         FIG. 8 b    illustrates a plan view of planar spiral coils for an inductive coupler. 
         FIG. 8 c    illustrates a plan view of a planar spiral coil for an inductive coupler. 
         FIG. 9 a    illustrates a schematic circuit diagram of a system including an inductive coupler providing galvanic isolation and signal transfer. 
         FIG. 9 b    illustrates a schematic circuit diagram of a system including a capacitive coupler providing galvanic isolation and signal transfer. 
         FIG. 10  illustrates a schematic diagram of a power conversion device including an inductive coupler providing galvanic isolation and signal transfer. 
         FIG. 11  illustrates an electronic component including at least two semiconductor devices with a bidirectional data exchange path including an inductive coupler. 
         FIG. 12  illustrates a detailed view of the connection structure to the contact pad of the inductive coupler of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top”, “bottom”, “front”, “back”, “leading”, “trailing”, etc., is used with reference to the orientation of the figure(s) being described. Because components of the embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. 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. The following detailed description, thereof, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     A number of exemplary embodiments will be explained below. In this case, identical structural features are identified by identical or similar reference symbols in the figures. In the context of the present description, “transverse” or “transverse direction” and “lateral” or “lateral direction” should be understood to mean a direction or extent that runs generally parallel to the lateral extent of a semiconductor material or semiconductor carrier. The lateral direction thus extends generally parallel to these surfaces or sides. In contrast thereto, the term “vertical” or “vertical direction” is understood to mean a direction that runs generally perpendicular to these surfaces or sides and thus to the lateral direction. The vertical direction therefore runs in the thickness direction of the semiconductor material or semiconductor carrier. 
     As employed in this specification, when an element such as a layer, region or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. 
     As employed in this specification, when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Galvanic isolation in power equipment refers to an arrangement in which an output power circuit is electrically and physically isolated from an input power circuit to prevent current flow. Energy or information can still be exchanged between the circuits by other means, such as capacitance, induction or electromagnetic waves, or by optical, acoustic or mechanical means. Galvanic isolation may be used where two or more electric circuits are to communicate, but their grounds are at different potentials, for example. Common reasons for providing galvanic isolation include safety from fault conditions in industrial grade products and applications in which communication between devices is needed but each device regulates its own power. 
     In some electronic systems, control functions are provided by lower voltage circuitry that is galvanically isolated from high-power circuitry. A bidirectional signal path between the lower-voltage circuitry and the higher-voltage circuitry can be used, for example, to transmit control data from a system controller to a power supply and to receive monitoring data from the power supply. When the high-power circuitry defines a power supply, high-voltage electrical isolation from earth or ground may be required for the power supply system by common industry practice or regulatory authorities. For reinforced galvanic isolation, examples of industry standards which may be referred to in such practices and regulations include ICE-60747-5-5 or VDE0884-11. For basic galvanic isolation, an example of an industry standard which may be referred to is IEC 60664-1 and VDE0884-11. 
     One way of providing a bidirectional signal path that provides galvanic isolation between higher-voltage circuitry and lower voltage circuitry is a transformer or inductive coupler in which the signal is transmitted inductively. 
     Embodiments described herein may be used to provide a connection structure for use in an inductive coupler and a device including at least one coil of an inductive coupler with a contact pad which is more robust in fault conditions and which may, when used, increase the operational lifetime of the inductive coupler or device. An inductive coupler may also be called a transformer. In some embodiments, the transformer is a coreless transformer including a primary coil and a secondary coil that are positioned close enough together to facilitate reliable data exchange and which are sufficiently isolated from one another to provide galvanic isolation. The primary and secondary coils may be planar coils that are integrated into a semiconductor die which may include further circuitry. 
     A further way of providing a bidirectional signal path that provides galvanic isolation between higher-voltage circuitry and lower voltage circuitry is a capacitive coupler in which the signal is transmitted capacitively. 
     Embodiments described herein may be used to provide a connection structure for use in a capacitive coupler. A capacitive coupler may include two conductive plates separated by a dielectric. The two conductive plates of the capacitive coupler may be integrated into a semiconductor die which may include further circuitry. 
       FIG. 1 a    illustrates a semiconductor device  20  including a galvanically isolated signal transfer coupler  21  including a contact pad  22  according to an embodiment. The galvanically isolated signal transfer coupler  21  may enable bidirectional signal exchange and may include an inductive coupler  23 , as illustrated in the embodiment of  FIG. 1 b    or a capacitive coupler  24  as illustrated in the embodiment of  FIG. 1   c.    
     The contact pad  22  includes a metallic base layer  25 , a metallic diffusion barrier layer  26  arranged on the metallic base layer  25  and a metallic wire bondable layer  27  arranged on the metallic diffusion barrier  26 . The metallic diffusion barrier layer  26  includes a first portion  28  that has a first outer surface  29  including a curved surface  30  at the periphery  31  and a second surface  32  opposing the first surface. The first portion  28  extends in a transverse plane and has a width. The metallic diffusion barrier layer  26  further includes a second portion  33  which protrudes from the second surface  32  intermediate the width of the first portion  28 . The width of the first portion  28  refers to the width, x, of the first portion  28  in the transverse plane. 
     Since the second portion  33  protrudes from the second surface  32  intermediate the width of the first portion  28 , the second surface  32  surrounds the second portion  33  on all sides at the junction between the first portion  28  and the second portion  29  or in other words, the first portion  28  extends on all sides from the second portion  33 . The lateral area of the first portion  28  is greater than the lateral area of the second portion  33 . The metallic diffusion barrier layer  26  has a shape which may be described as a mushroom-type shape with a head that has a lateral area that is greater than a lateral area of a pin protruding from the lower surface of the head. 
     The contact pad  22 , in particular, the first portion  28  or head includes a periphery with an outer curved surface extending towards the second surface  32  and the second portion  33  or pin of the metallic diffusion barrier layer  26 . The curved surface of the periphery avoids the presence of sharp edges at the outermost surface of the metallic diffusion barrier layer  28  which may assist in increasing the robustness of the galvanically isolated signal transfer coupler  21  to a fault condition, for example a transient voltage spike, and may assist in increasing the operational lifetime of the galvanically isolated signal transfer coupler  21  and semiconductor device  20 . 
     The central region of the first surface  29  may be substantially planar for accepting the head of a bond wire connection for coupling the galvanically isolated signal transfer coupler  21  to a circuit for signal transmission or exchange. The periphery  31  of the first surface  29  of the first portion  28  may have a radius of curvature, r, which lies within the range 0.5 to 2 times the maximum height of the first portion  28 . The metallic wire bondable layer  27  may conformally cover the first surface  29  of the first portion  28  and may also have a substantially planar central portion and curved surface at the periphery. 
       FIG. 1 b    illustrates a semiconductor device  20 ′ including the galvanically isolated signal transfer coupler  21  in the form of an inductive coupler  23  including a planar coil  34  which is coupled to the contact pad  22 . 
     The inductive coupler  23  may also be called a transformer and may be a coreless transformer. The inductive coupler  23  may be used for providing inductive bidirectional data exchange in a device having reinforced galvanic isolation. 
     The planar coil  34  may include an outer end formed by the contact pad  22 . The metallic base layer  25  of the contact pad  22  may be substantially coplanar with the windings of the planar coil  34  of the inductive coupler  21 . In some embodiments, the planar coil  34  is a spiral planar coil which includes the contact pad  22  at its outer end and includes a second contact pad at its inner end, which is positioned at the centre of the spiral. 
       FIG. 1 c    illustrates a semiconductor device  20 ″ including the galvanically isolated signal transfer coupler  21  in the form of a capacitive coupler including the contact pad  22 . The contact pad  22  forms a first plate  35  of a pair of plates  35 ,  36  providing a capacitor. The plates  35 ,  36  are spaced apart from one another by a dielectric  37 . 
     In some embodiments, the first portion  28  of the metallic diffusion barrier  26  of the contact pad  22  has a longitudinal axis extending substantially perpendicular to the transverse plane of the first portion  28  and the second portion  33  has a longitudinal axis which is aligned with the longitudinal axis of the first portion  28 . In these embodiments, the second portion  33  may be concentric with the first portion  28  such that the first portion extends laterally outwardly by substantially the same distance from the side faces of the second portion  33 . The contact pad  22  may be substantially circular in plan view. 
     The metallic diffusion barrier layer  26  may provide a barrier against diffusion between the material of the wire bondable layer  27  and the material of the metallic base layer  25  as well as providing a size and shape for reducing the electric field at edges of the contact pad  22  in the event of a voltage spike. 
     In some embodiments, the metallic base layer  25  may include copper, for example high purity copper. In these embodiments, the metallic diffusion barrier layer  26  may include nickel phosphorus and the metallic wire bondable layer  27  may include palladium. Palladium is suitable for forming a reliable low ohmic connection to wire bonds including gold or aluminium for example. 
     In embodiments including an inductive coupler  23 , the planar coil  34  and the metallic base layer  25  of the contact pad  22  may include copper, in particular high purity copper. 
     In some embodiments, a further metallic passivation layer is arranged on the metallic wire bondable layer  27 . The metallic passivation layer may be provided to prevent corrosion or oxidation of the metallic wire bondable layer  27 , for example during storage before application of the bond wire to the contact pad  22 . In the case of a wire bondable layer including palladium, the metallic passivation layer may include gold, for example. 
     In some embodiments, the wire bondable layer may be omitted and the outer surface of the metallic diffusion barrier  26  may provide a surface onto which a bond wire may be reliably attached. 
     In some embodiments, the metallic diffusion barrier layer  25  may include Ni, CoW or NiMoP. 
     In some embodiments, the contact pad includes a Cu anchoring layer having a size and shape corresponding to one of the embodiments of the metallic diffusion barrier layer  26 . In the case of a copper metallic base layer  25  and a copper anchoring layer, the copper anchoring layer is not required to have a metallic diffusion barrier function and so is better called an anchoring layer, since the mushroom-type form of the contact pad may be used to provide mechanical anchoring of the contact pad with the surrounding passivation and insulating layers. 
     The contact pad  22  and, in particular, the shape of the metallic diffusion barrier layer  26  may be formed by suitable selection and structuring of passivation and/or isolation layers and deposition techniques for depositing the contact pad  22  as is described with reference to  FIG. 2 . 
       FIG. 2  illustrates a schematic cross-sectional view of semiconductor device  40  including an inductive coupler  41  including a planar coil  42  coupled to a contact pad  43 . The contact pad  43  includes a metallic base layer  44  which is substantially coplanar with the planar coil  42 , a metallic diffusion barrier layer  45  arranged on the metallic base layer  44  and a metallic wire bondable layer  46  arranged on the metallic diffusion barrier  45 . 
     The inductive coupler  41  is integrated into a multilayer metallisation structure  47  arranged on an upper surface  48  of a semiconductor die  49 . The semiconductor die  49  may include silicon, for example single crystal silicon and may include one or more low-voltage semiconductor devices integrated in the semiconductor die  49  which are not illustrated in the view of  FIG. 2 . 
     Reliability of the conductive connection from the inductive coupler  41  to a further device or circuit under fault conditions may be improved with the assistance of an insulating passivation layer  50  arranged on an outermost surface  51  of the metallisation structure  47  which covers the planar coil  42  and peripheral regions of the metallic base layer  44 . The passivation layer  50  includes an opening  52  above the metallic base layer  44  of the contact pad  43 . The metallic diffusion barrier layer  45  is arranged in the opening  52  such that the opening  52  defines the size and shape of a lower portion  54  of the metallic diffusion barrier layer  45 . An upper portion  55  of the metallic diffusion barrier layer  45  extends over the passivation layer  50  adjacent to the opening  52  and includes a lateral area that is greater than a lateral area of the lower portion  54 . The planar coil  42  which is electrically coupled to the contact pad  43  may be integrated within the metallisation structure  47  arranged on the upper surface  48  of the semiconductor die  49 . 
     The metallic diffusion barrier layer  45  may be fabricated using galvanic deposition or electrochemical deposition such that the lower portion  54  grows on the exposed surface of the metallic base layer  44  upwardly and after filling the opening  52  in the passivation layer  54  continues to grow upwardly as well as outwardly such that a peripheral region  56  of an upper portion  55  is positioned on the passivation layer  50  and such that the outer surface  57  has a curved surface in the peripheral region  58 . 
     The upper portion  55  of the metallic diffusion barrier layer  45  provides a first portion extending in a transverse plane and having a width w which has a first surface  57  and a second surface opposing the first surface  57 . The first surface  57  includes a curved surface at the periphery in the peripheral region  58 . The lower portion  54  of the metallic diffusion barrier layer  45  provides a second portion that protrudes from the second surface of the first portion. The second portion protrudes from the second surface at a position intermediate the width w of the first portion. 
     Curved outer surfaces such as the peripheral region  58  of the contact pad  43  are useful in high-voltage devices, for example. In some embodiments, the side face  66  of the metallic base layer  44  may also have a curved form. Furthermore, at least the outer surface  67  of the outermost winding of the planar coil  42  and of the planar coil  60  may also have a curved form. 
     A metallic diffusion barrier layer including NiP may be fabricated using electrochemical deposition, CoW by electrochemical deposition, also called electroless deposition, NiMoP by galvanic and electro chemical deposition, Ni by galvanic deposition, for example. 
     The metallic diffusion barrier  45  may fill the opening  54  in the passivation layer  50  and cover the edge of the opening  54  at the upper surface of the passivation layer  50 . During the fabrication of the opening  54  in the passivation layer  50 , material of the underlying metallic base layer  44  may be deposited on the side walls of the opening  54  in the passivation layer  50 . Such material may have an elongate or spike form with edges which, if not adequately covered with further conductive material, could provide a site for failure due to the formation of a locally increased electric field in a fault condition such as a transient voltage spike. The shape of the metallic diffusion barrier  45 , which fills the opening  54  and neighbouring regions of the upper surface of the passivation layer  50  covers such material and may be used to avoid the presence of such a site. 
     The passivation layer may include Si x N y , in particular hydrogenated Si x N y . The thickness of the passivation layer  50  may lie in the range of 0.5 μm to 5 μm and the size of the opening  54  may lie in the range of 50 μm to 120 μm. 
     As is illustrated in  FIG. 2 , in some embodiments, the inductive coupler  41  may further include a second planar coil  60  which is arranged underneath the planar coil  42  and spaced apart from the planar coil  42  by one or more dielectric or isolation layers  61 . Some embodiments, the dielectric layer  61  may include silicon oxide. Both of the planar coils  42 ,  60  may be integrated into the metallization structure  47  on the semiconductor die  49 . 
     In some embodiments, the planar coils  42 ,  60  and the metallic base layer  44  may be fabricated by Damascene techniques. The metallisation structure  47  may include a silicon nitride layer  62  and a silicon oxide layer  63  such that the metallic planar coil  60  is positioned on the silicon nitride layer  62  and embedded within the oxide layer  63 . The silicon oxide layer  61  is arranged on the lower plane coil  60 , a silicon nitride layer  64  is arranged on the silicon oxide layer  61  and a further silicon oxide layer  65  is arranged on the silicon nitride layer  64 . The planar coil  41  and the metallic base layer  44  are arranged on the silicon nitride layer  64  and embedded within the silicon oxide layer  65 . The spacing between the planar coils  42 ,  60  and the material of the dielectric layer  61  may be selected such that the inductive coupler  41  provides basic or reinforced galvanic isolation which fulfils the requirements of VDE 0884-11, IEC 60664-1 or IEC 62368, respectively. 
       FIG. 3 a    illustrates a cross-sectional view of a portion of a mushroom-shaped contact pad  70  according to an embodiment, which may be used as the contact pad of an inductive coupler according to any one of the embodiments described herein.  FIG. 3 a    illustrates the dimensions which may be adjusted so as to provide reinforced galvanic isolation for high voltage applications.  FIG. 3 b    illustrates an enlarged view of an edge region of the contact pad  70 . 
     The contact pad  70  includes a mushroom-shaped metallic diffusion barrier layer  71  arranged on a planar metallic base layer  72 . The metallic base layer  72  may be part of metallization structure  74  arranged on an upper surface  75  of the semiconductor die  76 . The metallic base layer  72  may have a width w b . The contact pad  70  may be substantially circular in plan view such that the metallic base layer  72  and the metallic diffusion barrier layer  71  are also substantially circular plan view. In these embodiments, the width w b  of the metallic base layer  72  may correspond to the diameter of the substantially circular metallic base layer  72 . 
     An electrically insulating passivation layer  73  is arranged on the upper surface  77  of the metallisation structure  74  and on the periphery  78  of the metallic base layer  72 . In some embodiments, a distance l 1  of the periphery  78  of the metallic base layer  72  is covered by the passivation layer  73 . The passivation layer  73  defines an opening  79  exposing the central portion of the upper surface  80  of the metallic base layer  72  in which the metallic diffusion barrier layer  71  is arranged. The base of the metallic diffusion barrier  71  has a width w 2  corresponding to the width of the opening  79  in the passivation layer  73 . The passivation layer  73  may have a thickness t which defines the height of the second portion  81  of the metallic diffusion barrier layer  71 . The metallic diffusion barrier layer  71  may have an overall height h. The first portion  82  of the metallic diffusion barrier layer  71  may have a width w 1  which is greater than the width w 2  of the second portion  81  positioned within the opening  79  in the passivation layer  73 . The first portion  82  therefore extends from the opening  79  over the outermost surface  83  of the passivation layer  73  by distance l 2 . The width w 1  of the first portion  82  of the metallic diffusion barrier is greater than the width w 2  of the second portion  81  and is less than the width w b  of the metallic base layer. In the case of substantially circular contact pad  70 , distance l 2  corresponds to half of the difference in the width of the first portion  82  and the width of the second portion  81 , i.e. l 2 =(w 1 −w 2 )/2. 
     In order to achieve basic and/or reinforced galvanic isolation, the relationship between the thickness t of the passivation layer  73  and the length l 1  of the periphery  78  of the metallic base layer  72  which is covered by the passivation layer  73  may be suitably selected. In some embodiments, the ratio of t to l 1  lies in the range of 0.5 to 1, i.e. 0.5≤t/l 1 ≤1. 
     Furthermore, the ratio of the overall height h of the metallic diffusion barrier layer  71  to the extension l 2  may be selected such that it lies in the range of 1.5 to 2.5, i.e. 1.5≤h/l 2 ≤2.5. The periphery of the first portion  82  of the contact pad  70  includes a radius of curvature r. The ratio of the radius of curvature r to the height h of the metallic diffusion barrier layer  71  may lie in the range of 0.5≤r/h≤2. The radius of curvature r may be at least twice the thickness t of the passivation layer  73 , so that r&gt;t/2. The height h of the metallic diffusion barrier layer  71 , radius of curvature r of the periphery of the first portion  82  and the thickness t of the passivation layer  73  may be selected such that h≈t+r. 
     The metallic base layer  72  has a thickness t b . The radius of curvature r may be greater than a third of the thickness t b  of the metallic base layer  72  so that r≥t b /3. The length l 1  of the periphery  78  of the metallic base layer  72  which is covered by the passivation layer  73 , the radius of curvature r of the periphery of the first portion  82  and the thickness t b  of the metallic base layer may be selected such that r/3&lt;l 1 &lt;6t b . 
     As an example, the radius of curvature may lie in the range of 3 μm to 5 μm, the width w b  may be around 100 μm, the width w 2  may be greater than 20 μm, typically 80 μm to 90 μm and the width w 1  is greater than w 2  and less than w b  and may be around 85 μm to 98 μm. In some embodiments w 1 =w 2 +2r. The length l 1  may be around 10 μm. The length l 2  may be around 3 μm. The height h may be around 5 μm. The metallic base layer may have a thickness of around 3 μm. 
     Some embodiments provide a connection structure including a contact pad having a mushroom-type shape and a bond wire. The connection structure may be used to couple an inductive coupler or a capacitive coupler to a circuit or semiconductor device of a circuit to provide galvanic isolation and signal transmission. 
     As is indicated schematically by the dotted line  84  in the enlarged view of  FIG. 3 b   , the dimensions and the relationship between the dimensions of the contact pad  70  may be adjusted so as to achieve a value of the voltage at or near the surface of the contact pad  70  and of a bond wire  83  attached to the contact pad  70  which is more uniform and has a smoother form in order to provide reinforced galvanic isolation for high voltage applications. The dimensions and the relationship between the dimensions may be adjusted in order that the value of the voltage at or near the surface of the contact pad  70  and the bond wire  83  is as constant as possible. 
       FIG. 4  illustrates a connection structure  90  including a contact pad  91  and a bond wire  92  arranged on, and electrically coupled with, the contact pad  91 . The connection structure  90  may be used for inductive bidirectional data exchange in a device having reinforced galvanic isolation. For example, the connection structure  90  may be used in an inductive coupler, including an inductive coupler according to one of the embodiments described herein, or in a capacitive coupler, including a capacitive coupler according to one of the embodiments described herein. 
     The contact pad  91  includes a metallic base layer  93 , a metallic diffusion barrier layer  97  arranged on an upper surface  98  of the metallic base layer  93 , a wire bondable layer  99  arranged on the metallic diffusion barrier layer  97  and a metallic passivation layer  100  arranged on the metallic wire bondable layer  99 . In particular, after wire bonding, the metallic passivation layer  100  is arranged on the wire bondable layer  99  in regions outside of contact area between the head  101  of the bond wire  92  and the metallic wire bondable layer  99 . 
     The metallic base layer  93  may be positioned in an insulating layer of the metallisation structure  94  positioned on a surface of a semiconductor die which cannot be seen in the view of  FIG. 4 . In particular, the lower surface  95  and side faces  96  of the metallic base layer  93  may be embedded in a dielectric layer or passivation layer of the metallisation structure  94 . In some embodiments, the side faces  96  of the metallic base layer  93  may have a rounded form. 
     The connection structure  90  may also include a first passivation layer  102  arranged on an upper surface  103  of the metallisation structure  94  and on peripheral regions of the upper surface  98  of the metallic base layer  93 . The passivation layer  102  includes an opening  104  which is positioned above the central region of the upper surface  98  of the metallic base layer  93 . The lower portion of the metallic diffusion barrier layer  97  is arranged in this opening  104  and extends over the upper surface  105  of the passivation layer  102  such that the outer surface  106  of the metallic diffusion barrier layer  97  has a curved form at the periphery  107  and is substantially planar in the region above the opening  104 . The central substantially planar region  108  is suitable for producing a good mechanical and electrical connection between the head  101  of the bond wire  92  and the contact pad  91 . 
     The metallic diffusion barrier layer  97  includes a mushroom-type shape so that the upper portion has a larger area than the lower portion. The contact pad  91  may be substantially circular in plan view. The wire bondable layer  99  is arranged on the upper surface of the metallic diffusion barrier layer  97  and conforms to the curved surface of the periphery  107  such that the outer surface of the wire bondable layer  99  also has a curved form, and curves in the direction of the metallic base layer  93  in its peripheral region. The wire bondable layer  99  may be in contact with the upper surface  105  of the passivation layer  102  laterally adjacent the opening  104 . 
     The connection structure  90  includes a second isolation layer  109  which is arranged on the upper surface  105  of the passivation layer  102  and has a lateral extent such that it extends over the peripheral region  107  of the metallic diffusion barrier layer  97  and in particular onto the peripheral regions of the wire bondable layer  99 . The second isolation layer  109  defines an opening  110  exposing the central portion of the wire bondable layer  99 . The metallic passivation layer  100  is arranged in this opening  110  and therefore has a lateral extent which is less than the lateral extent of the metallic wire bondable layer  99 . 
     The materials of the various elements of the connection structure  90  may be selected so as to provide particular properties. In an embodiment, the metallic base layer  93  includes copper, in particular high purity copper. The wire bondable layer  99  includes palladium. In order to prevent diffusion between the palladium  99  of the wire bondable layer  99  and the copper of the metallic base layer  93 , the metallic diffusion barrier layer  97  may include nickel phosphorus, i.e. a nickel phosphorous alloy. The metallic passivation layer  100  may include gold, for example. The bond wire  92  may include gold or aluminium or Cu or a further metal or alloy capable of forming a low ohmic contact with palladium  99 . The interface region between the head  101  of the bond wire  92  and the wire bondable layer  99  may be free of the metallic passivation layer  100 . 
     The first passivation layer  102  may include hydrogenated silicon nitride so as to encourage charge trapping in the passivation layer and the second isolation layer  109  may include an imide, for example polyimide. An imide is useful since it adheres better to the palladium of the wire bondable layer  99  than to copper or nickel phosphorus and, therefore, to the metallic diffusion barrier layer  97  and the metallic base layer  93 . 
     The thickness and materials of the passivation layer  102  and second isolation layer  109  may be selected to provide suitable level of isolation between the bond wire  92  and further devices within the semiconductor die. 
     After formation of the bond wire connection, the contact pad  91  and bond wire  92  may be encapsulated in a mold compound. The arrangement of the second isolation layer  109  covering the interface between the passivation layer  102  and the metallic diffusion barrier layer  97  and the better adhesion between the second isolation layer  109  and metallic wire bondable layer  99 , may be used to hinder or prevent penetration of moisture from the overlying mold compound into this interface and reduce the likelihood of failure during a fault due to evaporation of moisture accumulated at this interface. 
       FIG. 5  illustrates a connection structure  120  which may be used for inductive or capacitive bidirectional data exchange in a device having reinforced galvanic isolation and in particular, reinforced galvanic isolation for sporadic, transient overvoltages and/or other interference voltages which may be caused by a lightning strike or other fault circuit for example. The connection structure may be used in a device having galvanic isolation rated for a 3 kV or 10 kV pulse. 
     The interconnection structure  120  differs from the interconnection structure  90  illustrated in  FIG. 4  in the arrangement of the additional isolation layers  121 ,  122  which increases the total thickness of the isolation layers in regions adjacent the contact pad  91  and bond wire  92 . 
     The connection structure  120  includes a contact pad  91  and a bond wire  92  having a similar structure to that illustrated in  FIG. 4 . The contact pad  91  includes the metallic base layer  93 , the metallic diffusion barrier layer  97 , the metallic wire bondable layer  99  and the metallic passivation layer  100 . The connection structure also includes the passivation layer  102  arranged on the upper surface  103  of the metallisation structure  94  and in the peripheral regions of the upper surface  98  of the metallic base layer  93  and second isolation layer  109 . 
     The connection structure  120  further includes a third isolation layer  121  which is arranged on the passivation layer  102  adjacent to the opening  104  and under the second isolation layer  109 . The third isolation layer  121  may have the form of a ring which is substantially concentric with the opening  104  and with the contact pad  91 . The third isolation layer  121  is arranged at a distance from the side faces  96  of the metallic base layer  93 . A fourth isolation layer  122  is arranged on the upper surface  123  and side faces  124  of the third isolation layer  121  and extends over the upper surface  105  of the passivation layer  102  to the opening  104  in the passivation layer  102 . 
     The fourth isolation layer  122  also defines an opening  126  which may have substantially the same lateral area as the opening  104 . The upper portion of the metallic diffusion barrier layer  97  is positioned on the further isolation layer  122  in regions immediately adjacent to the opening  126 . The wire bondable layer  99  also extends over the curved side faces of the upper portion of the metallic diffusion barrier layer  97  and is in contact with the fourth isolation layer  122 . The second isolation layer  109  is arranged on the fourth isolation layer  122  and on the peripheral regions of the wire bondable layer  99  as in the connection structure  90  illustrated in  FIG. 4 . After formation of the bond wire connection, the metallic passivation layer  100 , bond wire  92  and second isolation layer  109  may be encapsulated in a mold compound. 
     The passivation layer  102  may include hydrogenated Si x N y  and have a thickness of 2 μm and the second isolation layer an imide and have a thickness of 3 μm to 12 μm. The third isolation layer  121  may include phosphosilicate glass (PSG) or SiO x  and may have a thickness of 3 μm to 12 μm, typically 7 μm. The fourth isolation layer  122  may include hydrogenated Si x N y  and may have a thickness of 300 nm. The opening  110  in the second isolation layer  109  may have a diameter in the range of 50 μm to 120 μm. 
     As an example, for a nailhead bond connection, the bond wire  92  may have a diameter of 25 μm to 30 μm and the head  101  of the bond wire  92  a diameter of around 60 μm and a height of around 30 μm. 
       FIGS. 6 a  and 6 b    illustrate a contact pad  130  according to alternative embodiments. The contact pad  130  includes a metallic anchoring layer  131  arranged on a metallic base layer  132 . The metallic base layer  132  and the anchoring layer  131  may include Cu. The anchoring layer  131  has a size and shape corresponding to one of the embodiments of the metallic diffusion barrier layer and has a mushroom-type form with an upper portion with a greater lateral area than a lower portion. The upper portion has a periphery with a curved form, curving in the direction of the lower portion. The position and volume of the lower portion is defined by an opening in an insulation layer  134  which covers peripheral regions of a metallic base layer  132 . 
     In the case of a copper metallic base layer  132  and a copper anchoring layer  131 , the anchoring layer  131  is not required to have a metallic diffusion barrier function and so is better called an anchoring layer, since the mushroom-type form of the contact pad  130  may be used to provide mechanical anchoring of the contact pad  130  with the surrounding passivation and/or insulating layers  134 . The contact pad  130  may be used in a galvanically isolated signal transfer coupler  135  in the form of an inductive coupler or a capacitive coupler. 
     The anchoring layer  131  may be treated after deposition by wet etching, for example, to produce the curved form at the periphery of the upper portion. 
     In the embodiment illustrated in  FIG. 6 a   , the insulating layer  134  includes SiO x  and contact pad  130  may include an adhesion promotion layer  136 , which is arranged on the exposed portion of the upper surface  137  of the metallic base layer  132 , on the side walls of the opening  138  in the insulating layer  134  and on regions of the upper surface  139  of the insulting layer  134  adjacent the opening  138 . The upper portion  140  of the anchoring layer  131  is arranged on and extends outwardly from the adhesion promotion layer  136 . The lower portion  141  of the anchoring layer  131  fills the opening  138 . An insulating passivation layer  142 , for example a layer of Al 2 O 3  or Si x N y  having a thickness of not more than a few atoms, may be arranged on the outermost surface of the contact pad  130 . The insulating passivation layer  142  may cover the upper surface  139  of the insulating layer  134 , side face of the adhesion promotion layer  136  and free lying outer surfaces  143  of the anchoring layer  131 . 
     In the embodiment illustrated in  FIG. 6 b   , the insulating layer  134  includes Si x N y  and the anchoring layer  131  is in direct contact with the upper surface  137  of the metallic base layer  132 , the side walls of the opening  138  and the upper surface  139  of the insulating layer  134 . The contact pad  130  further includes one or more layers arranged on the outer surface of the anchoring layer. In some embodiments, a NiP layer  143  is arranged on the outer surface  146  of the anchoring layer  131 , a Pd layer  144  on the NiP layer  143  and a Au layer  145  on the NiP layer  144 . 
     The upper portion  140  of the anchoring layer  131  provides a first portion having an outer surface  146  or first surface and a second surface opposing the first surface. The first surface of this first portion has a curved surface at the periphery. The first portion extends in a transverse plane and has a width. The lower portion  141  of the anchoring layer  131  provides a second portion protruding from the second surface of the first portion intermediate the width of the first portion. 
       FIG. 7  illustrates a flow chart  150  of a method for fabricating a contact pad which may be used for an inductive coupler providing bidirectional signal exchange and basic and/or reinforced galvanic isolation. 
     In box  151 , a metallic diffusion barrier layer is deposited onto a surface of a metallic base layer exposed in an opening of a first isolation layer that covers a peripheral region of the metallic base layer such that the metallic diffusion barrier layer extends onto an outer surface of the first isolation layer. In box  152 , the metallic diffusion barrier layer is annealed. In box  153 , a metallic wire bondable layer is deposited onto the annealed metallic diffusion barrier layer. 
     The metallic diffusion barrier layer is annealed before the deposition of the subsequent metallic layer or layers. This method may be used so that the subsequently deposited layer can provide a seal for any gap that may be formed between the metallic diffusion barrier and the opening in the first isolation layer that may arise due to relaxation and contraction of the metallic diffusion barrier layer during annealing. 
     The outer surface of the metallic diffusion barrier may have a curved form at its periphery and extend towards the first isolation layer. The central position of the metallic diffusion barrier layer which is bounded by the periphery may be substantially planar. 
     The metallic diffusion barrier layer may be deposited using electro-chemical deposition or galvanic deposition depending on the composition. A NiP metallic diffusion barrier layer may be deposited using electro-chemical deposition. An external power source is used in galvanic deposition, whereas no external power source is used in electro-chemical deposition. Electro-chemical deposition is also referred to as electroless deposition. These methods may be used to produce an outer surface having a curved form at the periphery due to the growth mechanism of the metallic diffusion barrier on the first isolation layer in regions adjacent to the opening. 
     The metallic wire bondable layer may be deposited galvanically or by electroless deposition depending on the composition. For example, Pd may be deposited by electroless deposition and Ni by galvanic deposition. The wire bondable layer may conform to the shape of the underlying metallic diffusion barrier layer and also have a curved form at its periphery. 
     In some embodiments, a second isolation layer is deposited onto peripheral regions of the metallic wire bondable layer. The second isolation layer may include a material that has good adhesive properties to the wire bondable layer and/or better adhesive properties to the wire bondable layer compared to the metallic diffusion barrier layer. This arrangement may be used to prevent delamination of the second isolation layer from the conductive contact pad. 
     In some embodiments, a metallic passivation layer is deposited onto the metallic wire bondable layer such that the second isolation layer defines the lateral extent of the metallic passivation layer. The metallic passivation layer has a lateral extent that is less than the lateral extent of the underlying metallic wire bondable layer and head of the metallic diffusion barrier layer, since the second isolation layer is arranged on the peripheral region of the wire bondable layer. The metallic passivation layer may be used to hinder oxidation or contamination of the wire bondable layer during production and storage, in particular, before a wire bond is attached to the contact pad. The metallic passivation may not form a part of the bond between the wire bond and the contact pad. 
     A connection structure can be formed by applying a bond wire to the substantially planar central portion of the contact pad, for example using a nail head wire bonding technique. 
       FIG. 8 a    illustrates a perspective view of an example of an inductive coupler  160  which may be coupled to a circuit by the connection structure according to one of the embodiments described herein to provide galvanic isolation. The inductive coupler  160  may also be used in the device according to one of the embodiments descried herein. 
     The inductive coupler  160  includes a primary side  161  and a secondary side  162  whereby each of the primary side  141  and secondary side  162  includes at least one planar coil. In the embodiment illustrated in  FIG. 7 a   , each of the primary side  161  and the secondary side  162  includes two substantially coplanar spiral planar coils  163 ,  164 ;  168 ,  169 . The secondary side  161  includes a contact pad  165  arranged in the centre of the spiral planar coil  163 , a contact pad  166  which is arranged between and coupled to the outer end of the two spiral planar coils  163  and  164  and a contact pad  167  which is arranged in the centre of the spiral planar core  164 . 
     The shape and structure of the contact pad according to one of any one of the embodiments described herein may be used for the central pad  166 , whereby the metallic base layer is coplanar with and coupled to the planar coils  163 ,  164 . In some embodiments one or both of contact pads  165 ,  167  also includes a structure according to any one of the embodiments described herein. The shape, size and structure of the contact pads  165 ,  167  may be the same as that of the contact pad  166  or different. 
     The primary side  164  also includes two coplanar spiral planar coils  168 ,  169  which are positioned underneath and spaced apart by a dielectric layer  170  from the respective spiral planar coil  163 ,  164  of the secondary side  162 . The planar coils  168 ,  169 ,  163 ,  164  are electrically conductive and may be integrated on a silicon chip and, in particular, in differing layers of a multilayer metallisation structure. The spiral planar coils  163 ,  164 ,  168 ,  169  may include high purity copper and be fabricated using Damascene techniques, for example. 
     However, in other embodiments, the inductive coupler may include a single coil in the primary side  161  and a single coil in the secondary side  162 . The planar coil or coils need not be spiral and need not be substantially circular. 
       FIGS. 8 b  and 8 c    illustrate further embodiments of planar spiral coils which may be used for the primary or secondary side of an inductive coupler. 
       FIG. 8 b    illustrates an embodiment of an inductive coupler  160 ′ including two planar spiral coils  171 ,  172 , whereby a contact pad  173 ,  174  is arranged at the centre of each of the two planar spiral coils  171 ,  172  and the two planar spiral coils  171 ,  172  are coupled by a substantially S-shaped connection. The two planar spiral coils  171 ,  172  may be surrounded by a continuous conductive isolation coil  175 . 
       FIG. 8 c    illustrates an embodiment of an inductive coupler  160 ″ including a single planar spiral coil  176 , whereby a first contact pad  177  is arranged at the centre of the planar spiral coil  176  and a second contact pad  178  is arranged at the outer end of the planar spiral coil  177 . The planar spiral coil  176  and contact pads  177 ,  178  may be surrounded by a continuous conductive isolation coil  179 . 
     The device including the inductive coupler or capacitive coupler and the connection structure according to any one of the embodiments described herein may be used to provide galvanic isolation, such as basic galvanic isolation or reinforced galvanic isolation in various applications and circuits. 
       FIG. 9 a    illustrates a schematic view of a system  180  including a first circuit  181 , a second circuit  182  and galvanic isolation provided by an inductive coupler  183 . The inductive coupler  183  includes a first coil  184  electrically coupled to the first circuit  181  and a second coil  165  electrically coupled to the second circuit  182  and galvanic isolation  186  arranged between the first coil  184  and the second coil  185 . 
     The first circuit  181  and the second circuit  182  of the system  180  may include a single device or two or more devices forming a circuit. The inductive coupler  183  may include one or two coils on the primary side and the secondary side. The system  180  may be used for power conversion so that the circuits  181 ,  182  may include a power conversion system and a driver circuit, for example. 
       FIG. 9 b    illustrates a schematic view of a system  190  including a first circuit  191 , a second circuit  192  and galvanic isolation provided by two capacitive couplers  193 ,  194 . The first circuit  191  may be a high voltage circuit and the second circuit  192  a low voltage circuit. Alternatively, both the first circuit  191  and the second circuit  192  may be high voltage circuits or the first circuit  191  may be a low voltage circuit and the second circuit  192  may be a high voltage circuit. 
     Each capacitive coupler  193 ,  194  includes two conductive plates  195 ,  196 ;  195 ′,  196 ′ galvanically separated from one another by a dielectric material  197 ;  197 ′. The dielectric material  197 ;  197 ′ has a dielectric strength that is sufficiently high such that the required level of galvanic isolation, for example basic or reinforced, is provided. For example, the dielectric layer  197  can withstand a plate-to-plate voltage difference of 5 kV R m without suffering dielectric breakdown. 
     The capacitive coupler utilizes changes in capacitance to transmit signals. In operation, the first circuit  191  transmits data to second circuit  192  by encoding the data, and then placing encoded data signals in the form of pulses, RF waveforms, or glitches onto the plate  195 . The signals are capacitively coupled to low-voltage plate  196 , and are then detected and decoded by the second circuit  192 . 
     In the systems of  FIGS. 9 a  and 9 b   , the primary and secondary sides are galvanically isolated from the other and connected only through the inductive or capacitive couplers. The system may have the capability to provide bi-directional data between the primary side and the secondary side. In addition, power may be provided to the secondary side from the primary side. The primary side may drive the secondary side through one or more drivers (not illustrated) and the secondary side may provide data for sensing to the primary side. 
       FIG. 10  illustrates a schematic diagram of example of a power semiconductor module  200  which may include the inductive coupler and/or connection structure according to one or more of the embodiments described herein. The power semiconductor module  200  may include a capacitive coupler in place of the inductive coupler. The module  200  has three blocks  201 ,  202 ,  203 . Block  201  includes one or more driver circuits which may be integrated into a semiconductor driver component  204 . Block  202  includes a power section which may include two or more semiconductor switches  205 ,  206 , such as power transistors, which may be coupled to provide a half-bridge circuit, for example. 
     Block  203  ensures galvanic isolation between the driver circuit  201  and the power section  202 . The galvanic isolation can be integrated in the driver component  204  or be formed by a separate component. The galvanic isolation may be provided by an inductive coupler  207  having a contact pad according to one of the embodiments described herein. The inductive coupler may be coupled to the driver component  204  by a connection structure according to one of the embodiments described herein. The drive circuit  201  may be coupled to a further control unit  208  which is external to the module  200 . 
       FIG. 11  illustrates an example of an electronic component  210  including a first semiconductor die  211 , a second semiconductor die  212  and at least one inductive coupler  213  according to one of the embodiments described herein which provides reinforced galvanic isolation.  FIG. 12  illustrates the more detailed view of a portion of the inductive coupler  213  of  FIG. 12  and in particular, the bond wire connections  214  to the contact pads  215 ,  216 . 
     The inductive coupler  213  is coupled in the bidirectional signal exchange path between the first semiconductor die  211  and the second semiconductor die  212 . In the embodiment illustrated in  FIG. 11 , the inductive coupler  213  has the structure illustrated in  FIG. 8   a.    
     The first semiconductor die  211  is arranged on a first die pad  217  and the second semiconductor die  212  is arranged on a second die pad  218 . The second die pad  218  is spaced apart from the first die pad  217  and isolated therefrom by the mold compound  219  providing the housing  220  of the semiconductor component  210 . 
     The inductive coupler  213  is integrated into the metallization structure  221  arranged on the upper surface of the second semiconductor die  212 . The inductive coupler  213  is electrically coupled so as to provide a signal path between the first semiconductor die  211  and the second semiconductor die  212  by bond wires  214 . 
     The contact pad  215  which is coupled to the outer end of the two spiral planar coils  223 ,  224  of the inductive coupler  213  may have a structure according to one of the embodiments described herein and, in particular, may have a rounded or curved periphery. 
     The first semiconductor die  211  may include a logic, operation amplifier or a Schmitt trigger circuit and the second semiconductor die  212  may include a gate driver, or ADC (Analogue Digital Converter) circuit with Schmitt trigger. 
     Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper” and the like are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description. 
     As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise. It is to be understood that the features of the various embodiments described herein may be combined with each other, unless specifically noted otherwise. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.