Exposing Dies for Failure Analysis in Stacked Die Packages by Micro-Abrasive Blasting

摘要

For failure analysis in stacked die packages, exposing certain dies is necessary to get access to the active Integrated Circuit (IC) structures. Decapsulation by coplanar grinding is extremely challenging and is limited by package warpage and the thinnesses of silicon dies and Die-Attach (DA) tape. The micro-abrasive blasting technique described in this paper allows fast and reliable access to the different layers of the stacked package without restrictions by package warpage or small vertical dimensions. Micro-abrasive blasting removes the moulding compound and the brittle silicon of the top die. The ablation rates for both are in the same range, with slightly faster removal of the Moulding Compound (MC). Underlying dies are protected by the elastic DA tape, which backscatters the blasting particles. Dissolving the DA tape by chemical wet etching allows access to the undamaged underlying IC structures. Alternating micro-abrasive blasting and chemical wet etching steps are used for fast and efficient layer-by-layer preparation of the stacked die package.