Deprocessing is the systematic, controlled removal of successive layers from a completed semiconductor device to expose internal structures for inspection, analysis, and failure localization. This reverse-engineering and failure-analysis technique uses combinations of mechanical polishing, chemical etching, plasma etching, and laser ablation to strip passivation, metallization, dielectric, and active layers in sequence while preserving the integrity of remaining structures.

Why Deprocessing Matters in Semiconductor Manufacturing: Deprocessing is essential for root-cause failure analysis, competitive benchmarking, and IP verification because it provides direct physical access to internal device structures that are otherwise buried under multiple material layers.

• Layer-by-layer stripping — Sequential removal of passivation → top metal → via/ILD → lower metals → contacts → gate stack reveals each level independently for optical, SEM, or probe inspection • Chemical deprocessing — Wet etchants selectively target specific materials: HF for oxides, hot H₃PO₄ for nitrides, aqua regia for gold, FeCl₃ for copper, enabling clean interface exposure • Plasma deprocessing — RIE with endpoint detection provides uniform, large-area removal with nanometer-level control; O₂ plasma removes organics and low-k dielectrics selectively • Mechanical deprocessing — Parallel polishing and dimple grinding provide rapid bulk removal to approach regions of interest before switching to higher-precision methods • Laser-assisted deprocessing — Femtosecond laser ablation enables backside silicon thinning and localized material removal without thermal damage to adjacent structures

Deprocessing is the essential first step in physical failure analysis, transforming sealed, multilayer semiconductor devices into layer-by-layer inspection opportunities that reveal the physical root cause of electrical failures and process excursions.