A novel die to wafer (D2W) collective bonding method for MEMS and electronics heterogeneous 3D integration

Abstract

A new D2W collective bonding approach is demonstrated with functional MEMS devices with smaller than 3 × 3 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 8 inch ASIC wafers. The new package design was proposed in order to reduce the parasitic effect by attaching the released MEMS dice directly to the pads on an ASIC wafer. Two different types of MEMS devices having combs structure and a beam structure were used in order to confirm the minimal change in the MEMS functionality before and after D2W bonding. The ASIC wafer consisted of non functional circuit with pads and the daisy chain for measuring the electrical resistance and interconnection lead-out. With the new method by utilizing both the standard pick and place machine and the wafer bonder, ~ 800 numbers of functional MEMS dice were bonded to ASIC by low temperature D2W collective bonding at 200 degC for 2 minutes having an alignment tolerance less than 10% in 150 μm pitch with pad size of 75 μm. In this approach, the bonding time has been reduced by more than 50% in comparison with the conventional D2W bonding with flip chip bonder and performance of the package was improved by direct interconnection and the yield was improved by bonding with Known Good Dice.