Issues $\rightarrow$ Volume 27, Issue 3 (2026)

Joining in Microelectronics as an Open-System Problem: from Silicides to Direct Bonding

ABAKUMOV S.O.$^{1}$, CHEN Ch.$^{2}$, and GUSAK A.M.$^{1,3}$

$^1$Bohdan Khmelnytsky National University of Cherkasy, 82 Shevchenko Blvd, 18031 Cherkasy, Ukraine
$^2$National Yang Ming Chiao Tung University, No. 1001 Daxue Rd., East Dist., 300093 Hsinchu City, Taiwan
$^3$ENSEMBLE3 Centre of Excellence, 133 Wolczyńska, 01-919 Warsaw, Poland

Received / final version: 03.06.2026 / 05.08.2026 Download PDF logo PDF

Abstract
Joining processes in microelectronics are traditionally analysed within separate technological frameworks, including silicide formation, soldering, intermetallic growth, direct bonding, and reliability degradation. In this review, we argue that these seemingly diverse phenomena can be understood within the unified physical framework of flux-driven transformations in open systems under geometrical and mechanical constraints. We revisit several key developments in reactive-diffusion theory relevant to microelectronics, including sequential phase formation in silicides, nucleation and growth under sharp concentration gradients, flux-driven ripening during soldering, vacancy-induced porosity evolution, and stress-assisted direct metal bonding. Particular attention is paid to the role of transport-path topology, competition between characteristic kinetic processes, and the coupling between diffusion, reaction, and defect evolution. Reactive soldering and direct bonding are interpreted as two complementary classes of non-equilibrium morphological evolution. In soldering systems, sustained atomic fluxes may generate connected porous networks and flux-driven instabilities, whereas in direct bonding, the same diffusion mechanisms progressively eliminate interfacial free volume and establish metallic continuity. Reliability degradation is further discussed as a continuation of the same open-system dynamics through electromigration, void coalescence, and collective damage evolution. The review emphasises that microelectronic joining phenomena are governed not only by equilibrium thermodynamics, but also by kinetic constraints imposed by external fluxes, evolving transport networks, and mechanical fields. This perspective provides a common conceptual language for understanding phase selection, morphology evolution, bonding, and failure in modern microelectronic interconnect technologies.

Keywords: diffusion, joining, reactions, soldering, wetting, direct bonding, phase selection, nucleation, cellular decomposition, flux-driven ripening, Kirkendall voiding, reliability.

DOI: https://doi.org/10.15407/ufm.27.03.***

Citation: S.O. Abakumov, Ch. Chen, and A.M. Gusak, Joining in Microelectronics as an Open-System Problem: from Silicides to Direct Bonding, Progress in Physics of Metals, 27, No. 3: ***–*** (2026)

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