Microscale laser shock processing (LSP) of metal thin films

Microscale Laser Shock Processing (LSP) is a technique that may be potentially used to manipulate the residual stress distributions in metal film structures and thus improve the reliability performances of micro-devices. In this study, microscale LSP of copper thin films on single crystal silicon substrates is investigated. Curvature measurements verify that substantial average compressive residual stress can be induced in copper thin films using microscale LSP. High spatial resolution is required to measure the stress/strain field in microscale LSP. For the first time, X-ray microdiffraction technique based on diffraction intensity contrast method is used to measure the relative variation of the stress/strain field in the shock treated copper thin films. The experimental results are further understood through 3D FEM analysis.