Microscale Laser Shock Peening of Thin Films, Part 1: Experiment, Modeling and Simulation

Microscale Laser Shock Peening (LSP), also known as Laser Shock Processing, is a technique that can be potentially applied to manipulate residual stress distributions in metal film structures and thus improve the fatigue performances of micro-devices made of such films. In this study, microscale LSP of copper films on single crystal silicon substrate is investigated. Before and after-process curvature measurement verifies that sizable compressive residual stress can be induced in copper thin films using microscale LSP. Improved modeling work of shock pressure is summarized and the computed shock pressure is used as loading in 3D stress/strain analysis of the layered film structure. Simulation shows that the stress/strain distribution in the metal film is close to equi-biaxial and is coupled into the silicon substrate.