Authors:

Ethan Xinghan Tan

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About Paper:

As 3D heterogeneous integration becomes the state-of-the art solution to advanced packaging, bonding reliability between layers becomes a key challenge. Hybrid bonding, which bond dielectric and copper surfaces simultaneously and directly to themselves, has emerged as a leading technique. Recent research has proposed polyimide as a substitute for traditional oxide dielectrics due to its thermal stability and lower bonding temperature. Polyimide's bonding performance after plasma surface activation and its compatibility with copper metallization processes require further investigation. This project evaluates the effect of plasma treatment on polyimide surfaces and the effects of different processing variables on a robust copper electroplating process. Initial work involves reviewing the impact of varying temperature and thicknesses during plasma surface activation on polyimide adhesion, with attention to surface roughness, functional group introduction, and wettability. These will be assessed through surface characterization techniques including X-ray Photoelectron Spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). In parallel, a copper electroplating setup is developed to simulate post-activation metallization, using a simple acidic sulfate bath and common lab apparatus. Key process variables such as current density, bath temperature, additive concentration, and agitation are optimized for uniform copper deposition. The copper electroplating performance will be evaluated by optical microscopy and thickness measurement via profilometers. This study provides foundational insights into copper metallization methods and plasma activated polyimide, laying the groundwork for the development of a polyimide hybrid-bonding process. Results will inform whether polyimide, when properly treated and metallized, is a suitable dielectric for hybrid bonding applications. Keywords: Heterogeneous Integration; Copper; Polyimide; Hybrid Bonding † Presenting Undergrad Author; ‡ Contributing Undergrad Author; * Undergrad Acknowledgment

Source:

Purdue University / 2025

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Co-authors:

Ethan Xinghan Tan