Cedric Corley-Wiciak | Searcharxiv

arXiv2026

Subgrain-resolved Analysis of Degradation in Cu Metallization via Scanning 3DXRD and Thermomechanical Modeling

Metallization layers play a key role in the performance and reliability of modern power semiconductor devices. During short-circuit events, rapid heating of power metallization layers induces thermomechanical incompatibility stresses, which may contribute to material degradation and impact device performance. In this work, potential degradation hotspots associated with thermomechanical loading in Cu power metallization are investigated using a combined experimental--computational approach. Scanning three-dimensional X-ray diffraction measurements are coupled with thermomechanical crystal plasticity simulations to probe the evolution of grain-resolved plastic deformation during rapid cyclic loading. This integrated approach provides insight into the microstructural processes governing degradation hotspot formation, laying the groundwork for future microstructure-informed, physics-based reliability assessment of Cu metallization.

cond-mat.mtrl-sci↗

arXiv2024

Ge epitaxy at ultra-low growth temperatures enabled by a pristine growth environment

Germanium (Ge), the next-in-line group-IV material, bears great potential to add functionality and performance to next-generation nanoelectronics and solid-state quantum transport based on silicon (Si) technology. Here, we investigate the direct epitaxial growth of two-dimensional high-quality crystalline Ge layers on Si deposited at ultra-low growth temperatures ($T_{Ge} = 100^{\circ}\mathrm{C}-350^{\circ}\mathrm{C}$) and pristine growth pressures ($\lesssim 10^{-10}\,\mathrm{mbar}$). First, we show that $T_{Ge}$ does not degrade the crystal quality of homoepitaxial Ge/Ge(001) by comparing the point defect density using positron annihilation lifetime spectroscopy. Subsequently, we present a systematic investigation of the Ge/Si(001) heteroepitaxy, varying the Ge coverage ($θ_{Ge}$, 1, 2, 4, 8, 12, and 16 nm) and $T_{Ge}$ ($100^{\circ}\mathrm{C}$ to $300^{\circ}\mathrm{C}$, in increments of $50^{\circ}\mathrm{C}$) to assess the influence of these parameters on the layer's structural quality. Atomic force microscopy revealed a rippled surface topography with superimposed grainy features and the absence of three-dimensional structures, such as quantum dots. Transmission electron microscopy unveiled pseudomorphic, grains of highly crystalline growth separated by defective domains. Thanks to nanobeam scanning x-ray diffraction measurements, we were able to evidence the lattice strain fluctuations due to the ripple-like structure of the layers. We conclude that the heteroepitaxial strain contributes to the formation of the ripples, which originate from the kinetic limitations of the ultra-low temperatures.

cond-mat.mtrl-sci↗