Copper electroplating into deep microvias for the “SiP” application

International audienceIn order to anticipate the further demands of miniaturization and integration of ‘‘System-in-Package”, thetechnology of 3D through-silicon-vias (TSVs) has been developed at NXP Semiconductors. The sputteringand the electroplating have been chosen for realize respectively a copper seed layer and a thick copperdeposition inside 75 lm 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 lm thick copper layer. To achieve a thickmicrovia filling, the pulsed current is preferred and a perpendicular electrolyte flow is critical. With an11 lm thick patterned photoresist mask on the field, the 75 lm diameter and 180 lm deep microviascan be more-than-the-half filled using the ‘‘superfilling” recipe when the field depositing layer reachesthe mask level. Such partially filled microvias exhibit excellent electrical resistances within the rangeof 4 mX