TY - JOUR

T1 - The influence of chemistry on the interface toughness in a WTi-Cu system

AU - Alfreider, Markus

AU - Bodlos, Rishi

AU - Romaner, Lorenz

AU - Kiener, Daniel

N1 - Publisher Copyright: © 2022

PY - 2022/5/15

Y1 - 2022/5/15

N2 - With a considerable amount of commonly used material systems consisting of individual, rather confined layers, the question for mechanical behaviour of their individual interfaces arises. Especially, when considering varying interfacial structures as a result of the processing environment. Furthermore, the interaction between pronounced plasticity and fracture processes can lead to challenges with regards to separation between sole interface- or bulk properties.The present work investigates the interfacial fracture characteristic of a WTi-Cu sytem commonly found in the microelectronics industry as a heterogeneous model material with pronounced plasticity in the Cu phase. To study this behaviour on a rather limited scale (<6 µm), microcantilever experiments were conducted and evaluated using a continuous J-Δa curve evaluation scheme with classical elastic-plastic considerations in mind. A change in interface chemistry, resulting from air exposure between processing steps, was probed and found to show distinct crack propagation along the interface opposed to crack tip blunting as encountered in the vacuum processed sample. Complementary density functional theory calculations also showed a strong reduction of interface cohesion upon oxygen accumulation and a model framework based on classical dislocation plasticity considerations revealed the transition from plasticity to fracture processes to be a result of shielding and following change in mode mixity.

AB - With a considerable amount of commonly used material systems consisting of individual, rather confined layers, the question for mechanical behaviour of their individual interfaces arises. Especially, when considering varying interfacial structures as a result of the processing environment. Furthermore, the interaction between pronounced plasticity and fracture processes can lead to challenges with regards to separation between sole interface- or bulk properties.The present work investigates the interfacial fracture characteristic of a WTi-Cu sytem commonly found in the microelectronics industry as a heterogeneous model material with pronounced plasticity in the Cu phase. To study this behaviour on a rather limited scale (<6 µm), microcantilever experiments were conducted and evaluated using a continuous J-Δa curve evaluation scheme with classical elastic-plastic considerations in mind. A change in interface chemistry, resulting from air exposure between processing steps, was probed and found to show distinct crack propagation along the interface opposed to crack tip blunting as encountered in the vacuum processed sample. Complementary density functional theory calculations also showed a strong reduction of interface cohesion upon oxygen accumulation and a model framework based on classical dislocation plasticity considerations revealed the transition from plasticity to fracture processes to be a result of shielding and following change in mode mixity.

KW - Crack extension

KW - Density functional theory

KW - Interface toughness

KW - Thin films

UR - http://www.scopus.com/inward/record.url?scp=85126593107&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2022.117813

DO - 10.1016/j.actamat.2022.117813

M3 - Article

AN - SCOPUS:85126593107

VL - 230.2022

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

IS - 15 May

M1 - 117813

ER -