Die Thickness - a Neglected Design Parameter

Electromagnetic interactions on-chip, at radio frequencies, are often unavoidable phenomena that designers must account for at the system level. While viable strategies to limit interference have been presented previously, the efficacy of die-thinning as a mitigation strategy has been underexplored in the available literature. Die-thinning is given focused attention in this work through a series of experiments with an electromagnetic simulator, where the passive structure of choice is the inductor. These simulations, conducted with EMX, demonstrated that for Q-value penalties of less than 30%, reductions in coupling by over two orders of magnitude are achievable. Additionally, the effects of an holistic approach, whereby separation, inductor topology, and die-thickness are optimized, is shown to yield coupling coefficients of 10–<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> or below for appropriate inductor geometries with realizable spacing constraints.