Local modification of thin film metal by laser peening

激光喷丸是一种改善力学性能的表面处理方法。传统上，LP被应用于块状材料，并在水介质中进行处理以防止等离子体的膨胀，在本研究中，将这种处理应用于薄膜金属。LP有可能成为一种新型的薄膜金属处理方法，但传统的湿法处理不适用于薄膜。因此，提出了干态液化法，用透明固体材料代替水作为介质。选择玻璃作为干式液压机的固体介质是因为它比传统的湿式液压机具有更高的硬度改善。此外，还考虑了试件与固体介质之间的气隙。结果表明，喷丸效果小于0.1 mm的间隙厚度。最后，将所提出的干式液压法应用于溅射沉积的铜膜，提高了膜层的硬度。

Laser peening (LP) is a surface treatment method for improving mechanical properties. Conventionally, LP has been applied to bulk material and the treatment is conducted under water medium to prevent expansion of plasma.In this research, to apply this treatment to thin film metals is objective. The LP has possibility to be a novel treatment method of thin film metal, however the conventional wet-condition treatment is not suitable for thin films. Therefore, LP under dry condition is proposed.Dry LP uses transparent solid material instead of water for medium. Glass is chosen for the solid medium of dry LP because it shows higher improvement of hardness than that of conventional wet LP. In addition, air gap between specimen and solid medium is considered. As results, the peening effect is confirmed less than 0.1mm of the gap thickness. Finally, the proposed dry LP is applied to thin copper film deposited by sputtering and hardness of the film is improved.