Copper electroplating into deep microvias for the SiP application
In order to anticipate the further demands of miniaturization and integration of System-in-Package, the technology of 3D through-silicon-vias (TSVs) has been developed at NXP Semiconductors. The sputtering and the electroplating have been chosen for realize respectively a copper seed layer and a thick copper deposition inside 75?m wide and hundreds micrometer deep microvias. The microvias, for an aspect-ratio (AR) up to 2.3, can be successfully covered by a sputtered 3?m thick copper layer. To achieve a thick microvia filling, the pulsed current is preferred and a perpendicular electrolyte flow is critical. With an 11?m thick patterned photoresist mask on the field, the 75?m diameter and 180?m deep microvias can be more-than-the-half filled using the superfilling recipe when the field depositing layer reaches the mask level. Such partially filled microvias exhibit excellent electrical resistances within the range of 4m?.
copper electroplating microvias sip copper seed coating