according to an illustrated exemplary embodiment , a bond pad condition testing or monitoring structure in an integrated circuit device , for detecting anomalous electrical characteristics of the structure , as being indicative of a propensity of a failure of the bond pad , is formed in a metal layer defining metal wirings . as depicted in fig1 , a metal layer 1 of defined wirings of an integrated circuit has , defined in an area 2 coincident with the footprint of an overhanging bond pad 3 , defined in an upper metal layer 4 over an inter - metal dielectric layer 5 , one or more finger portions 6 interconnected together that , according to the exemplary embodiment shown , may extend from a common base strip ( not visible in fig1 ). the one or more finger portions 6 extend from the common base strip in a hair comb shape , laterally separated from a specular hair comb array of one or more finger portions 7 , similarly extending from a base strip ( not visible in fig1 ) and intermeshed with the fingers 6 of the first array . the first hair comb array of interconnected finger portions 6 connects to the integrated circuit wiring ( not visible in fig1 ) and , through numerous metal interconnects ( vias ) 8 purposely made through the dielectric inter - metal layer 5 , to the overhanging bond pad 3 , forming a substantially equipotential metal structure of the integrated circuit node made accessible through the pin of the packaged device wired to the bond pad 5 . differently , the other hair comb array of interconnected finger portions 7 is electrically isolated from the first array and from the correspondent integrated circuit node , though remaining capacitively coupled to the overhanging bond pad across the dielectric inter - metal layer 5 forming the passive sense structure . fig2 and 3 are a schematic orthogonal cross - sectional view and a plan view , respectively , of the integrated structure of the bond pad and of the sense structure defined underneath it , as illustrated in fig1 . in mock - up test samples used for verifying effectiveness and reliability of the pad condition testing sense structure of this disclosure , and the thicknesses ( a ) and ( b ), indicated in fig2 , were respectively varied within the ranges : 0 . 5 to 6 . 0 μm for ( a ) and 0 . 4 to 1 . 0 μm for ( b ). as will be evident to the expert reader , the metal layer 1 may eventually correspond to the would - be top most metal layer defining the wirings of the integrated circuit , and the upper metal layer 4 , defining the bond pads of the packaged semiconductor device , may even be a purposely added metal layer . as may be customary , after definition of the bond pads and bonding of the ball termination of the connecting wire ( typically of gold ), a passivation topping layer 9 of polymide may be deposited over the defined parts of the upper metal layer 4 . fig4 shows the equivalent electrical circuit of the passive sense structure according to the embodiments described herein . the symbolic electrical components correspond to the distributed resistance and inductance , and to the coupling capacitance of the physical structure created underneath the bond pad metal . the input and output arrows indicate respective connection wirings departing , for example , from opposite ends of a base strip of the interconnection of all the finger portions 7 , spaced apart on the footprint area 2 . the respective connection wirings are adapted to connect , respectively , to a source of a voltage step stimulating signal and to an inverting input of a comparator . the output state of the components depends on the result of the comparison of the step response waveform of the passive sense structure having a complex inductance . the output state is characterized by a significant reactive component , with a reference waveform or with equivalent time - correlated voltage thresholds . even maintaining customarily minimized bond pad sizes , resistances , inductances , and coupling capacitances of the equivalent circuit of the passive sense structure may be tailored for enhanced sensitivity by changing the defined patterns of the two isolated parts in the footprint area of the metal . patterns , other than two intermeshed comb - like parts , as exemplified in the figures may be implemented , such as , for example , two intertwined spirals , and other pairs of intertwined parts , which may eventually account for dissimilar total areas for incrementing the coupling capacitance of the sense structure at a detriment of the total area of the equipotential part connecting to the overhanging bond pad . fig5 schematically depicts the basic circuit arrangement for stimulating the sense structure by applying a voltage step signal to it , and analyzing its step response waveform to detect an anomalous or modified behavior . the anomalous or modified behavior may eventually be signalled by an output stage adapted to produce a diagnostic signal indicative of the output state of the comparator consequent to a voltage step stimulus of the passive sense structure . as will be readily recognized by the expert reader , the relative simplicity of implementation of both the voltage step source and the step response analyzing circuitry ( sensing circuitry ), makes a partial or whole integration of the sensing system in the packaged integrated circuit device that will thus be offering an embedded sub - system useful for monitoring in , time the bond pad condition possible and economical .