1. Purpose and scope
A package technology is built from unit processes, and most new technologies need several that the provider has not run before or not at the new pitch. Each module has its own physics and failure modes: plating uniformity and voids in bumps and pillars, line and space and adhesion in redistribution layers, die shift and warpage in fan-out moulding, via fill and stress in through-silicon vias, bow and cracking in thinning, surface preparation, cleanliness and alignment in hybrid bonding, non-wets and bridges in fine-pitch attach, and voids in underfill. The purpose of this stage is to take each module to capability: it meets its targets inside a measured process window on development tools.
Module engineers work in short loops. They run recipe splits planned by design of experiments, measure the results with inline metrology and inspection, cross-section the structures and use short-loop test vehicles to measure electrical results where they can. The work happens partly in the wafer fab, for steps such as through-silicon vias and bonding surface preparation, and partly in the packaging line.
In scope: module process specifications, recipe development, process windows, module capability reports and the material qualification data the modules generate. Out of scope: joining modules into one flow, which is Process Integration & Baseline, and final tool selection and qualification, which is Equipment Selection & Qualification.
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