Surface modification of copper using high intensity, 1015 W/cm2, femtosecond laser in vacuum

A study of copper target surface modification with high intensity (1015 W/cm2, fluence of ∼300 J/cm2) Ti:sapphire laser, operating at 800 nm wavelength and pulse duration of 60 fs is presented. The Cu surface variations were studied in vacuum ambience. The copper target specific surface changes and phenomena observed are: (i) creation of craters (with extra-low diameters); (ii) formation of periodic surface structures especially expressed at the reduced intensity; (iii) presence of the “clean” surface in the irradiated zone (mainly absence of the oxide(s)), and (iv) occurrence of plasma in front the surface, emitting predominantly X-ray radiation (soft and hard). It can be concluded from this study that the reported laser intensities can effectively be applied for copper surface modification. The appearance of plasma in front of the target, irradiating in the X-ray/UV region, offers additional effect of surface purification facilitating contaminant-free conditions which is highly important for specific applications, e.g. in microelectronics. Generally, femtosecond laser surface modification of copper is non-contact and very rapid compared to traditional modification methods.