Film thickness dependent microstructural changes of thick copper metallizations upon thermal fatigue

Year: 
2017
Month: 
6
Day: 
15
Pages: 
2022-2034
DOI: 
10.1557/jmr.2017.199
Type: 
Journal Articles
Journal: 
Journal of Materials Research
Volume: 
32
Abstract: 

With increasing performance requirements in power electronics, the necessity has emerged to investigate the thermo-mechanical behavior of thick Cu metallizations ($5 lm). Cu films on rigid substrates in the range of 5–20 lm were thermally cycled between 170 and 400 °C by a fast laser device. Compared to the initial microstructures, a texture transition toward the {100} out-of-plane orientation with increasing film thickness was observed during thermo-mechanical cycling, along with an abnormal grain growth in the {100}-oriented grains and a gradual development of substructures in a crystallographic arrangement. Compared to the well-studied thin Cu film counterparts (#5 lm), the surface damage showed a 1/hf dependency. Transition from an orientation independent (hf 5 5 lm) to an orientation specific thermo-mechanical fatigue damage (hf 5 10, 20 lm) was observed following a higher damager tolerance in {100} oriented grains.