Figure 1. Circuit-diagram of a low-side switch driving an inductive load. The relationship between voltage, current and temperature is displayed at the right side. The high power dissipation during the switchoff causes a sharp temperature rise. Figure 2. SEM-image of a DMOS-switch with aluminum in the power metallization after exposure to power-cycle stress. A massive buckling of the metallization and passivation cracks are visible, as well as aluminum extrusions at the broken edges Abstract-In this article the failure behavior of DMOSswitches under power-cycle stress is shown to be dominated by thermo-mechanical deformation of the metallization. The failure evolves without a significant influence from electromigration stress.
This paper reports on the strain rate dependence of the mechanical properties of aluminum-based metallization layers. Evaporated Al, sputtered Al 99% Cu 1% , and multilayers of µm-thick Al 99% Cu 1% films separated by thinner TiN/Ti layers are characterized using the bulge test, the microcompression method and the microtensile technique. Elastic, ductile and fracture parameters are extracted for strain rates dε/dt between 10 -4 to 10 1 s -1 . The Young's modulus E of sputtered layers, 59 GPa, is marginally lower than that of evaporated films, 63 GPa. Both fracture strain ε max and strength σ max of sputtered Al, 5.5% and 79 MPa, respectively, show no significant variation with dε/dt, changing to ε max = 2.1 % and σ max = 200 MPa when such films are stacked with TiN/Ti layers. Regarding evaporated Al, the failure parameters depend strongly on the strain rate: ε max decreases from 33.2 to 1.3% and σ max increases from 153 to 380 MPa within the entire range of tested dε/dt values.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.