Probing the Nanoscale Onset of Plasticity in Electroplated Copper for Hybrid Bonding Structures via Multimodal Atomic Force Microscopy

Published

December 19, 2025

Author(s)

Gheorghe Stan, Nicolas Alderete, Cristian Victor Ciobanu, Paresh Daharwal

Abstract

The slowdown of Moore's law has elicited a paradigm shift whereby 2D shrinking is being replaced by 3D-stacking advanced packaging approaches to satisfy the ever-increasing demands for power, performance, area, and cost. Driven by the widespread use of metallic interconnects with submicron pitches, robust metrology and understanding of size effects on the elastic-plastic behavior of materials are of primary interest. Here, we develop an Atomic Force Microscopy (AFM)-based protocol for characterizing the incipient stages of plasticity and illustrate it on hybrid bonding-ready (prior to bonding) copper pads. Together with AFM's high spatial-resolution imaging capabilities, we employed contact resonance, single- and multi-step indentation to characterize mechanical heterogeneity, quantify the statistics of nanoscopic yield stress, and derive indentation stress-strain curves at room temperature, respectively. From these measurements, we have clarified the mechanisms of early plasticity and determined the elastoplastic constitutive response of polycrystalline copper, including parameters such as elastic modulus, yield stress, and strain-hardening slope. Besides providing metrology relevant to various length scales, our approach offers a pathway to utilize an industry-standard instrument for characterizing the thermomechanical properties that are essential for the development of semiconductor structures.

Citation

ACS Applied Nano Materials

Pub Type

Journals

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https://doi.org/10.1021/acsanm.5c05142

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Keywords

atomic force microscopy, nanoscale plasticity, copper, advanced packaging, hybrid bonding

Citation

Stan, G. , Alderete, N. , Ciobanu, C. and Daharwal, P. (2025), Probing the Nanoscale Onset of Plasticity in Electroplated Copper for Hybrid Bonding Structures via Multimodal Atomic Force Microscopy, ACS Applied Nano Materials, [online], https://doi.org/10.1021/acsanm.5c05142, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960439 (Accessed October 9, 2026)

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