Biocompatible encapsulation and interconnection technology for implantable electronic devices

摘要

A biocompatible packaging process for implantable electronic systems is under development at imec, combiningbiocompatibility, hermeticity, extreme miniaturization and cost aspects.In a first phase of this packaging sequence, hermetic chip sealing is performed by encapsulating all chips to realizea bi-directional diffusion barrier preventing body fluids to leach into the package causing corrosion, and preventingIC materials such as Cu to diffuse into the body, causing various adverse effects. For cost effectiveness, this chipsealing is performed as post-processing at wafer level, using modifications of standard clean room (CR) fabricationtechniques. Well known conductive and insulating CR materials are investigated with respect to theirbiocompatibility, biostability, diffusion barrier properties and sensitivity to corrosion. Material selection andintegration aspects are modified until good properties are obtained.In a second phase of the packaging process, all chips of the final device should be electrically connected, applying abiocompatible metallization scheme. We selected the use of Pt due to its excellent biocompatibility and corrosionresistance. Since Pt is very expensive, a cost effective Pt-selective plating process is developed.During the third packaging step, all system components such as electronics, passives, a battery,... will beinterconnected. To provide sufficient mechanical support, all components are finally embedded using a medicalgrade elastomer such as PDMS or Poly-urethane.