A New, Efficient Method for Preparation of 3D Integrated Systems by Laser Techniques

Abstract

Miniaturization trend progresses continuously and enables an increasing integration level up to 3D system in package (3D-SiP). Thus, the structure of electronic packages is getting more and more complex and the material compositions often are heterogeneous mixtures of metals, polymers and ceramics. This causes challenging requirements for the investigation and reliability characterization of materials, interfaces, components and systems. The target positions are often buried or covered. Additionally the cover and housing materials are increasingly designed for harsh environment applications and so resistant against chemical attack. All these developments make the preparation for e.g. local access to perform electrical measurements or artefact free cross sectioning more and more complex. Focused ion beam preparation is limited in terms of ablation volume. Chemical decapping does not allow opening a small area very selectively and fails increasingly on the resistivity of the mold compounds against chemicals. Metallographic cross sectioning does not preserve the function of the system or can introduce artifacts which are limiting further investigations like element detection or thin film microstructure analyzes. Within all these difficulties the paper presents a new laser preparation tool for multi-purpose capabilities in failure diagnostics and reliability investigations. Several case studies show that the tool is usable for target and large area decapsulation of molding and protective gel coverage materials with no significant thermal impact. Also stacked die preparation for 3D package analyzes and pre-preparation for multi-position TEM lamellas are possible.