Copper electroplating into deep microvias for the “SiP” application
Résumé
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 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 thick
microvia filling, the pulsed current is preferred and a perpendicular electrolyte flow is critical. With an
11 lm thick patterned photoresist mask on the field, the 75 lm diameter and 180 lm 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 4 mX.