Product Code: ICAL05_M602

Effect of Pulse Parameters on Laser Cleaning of Copper Oxides
Authors:
Jie Zhang, Columbia University; New York NY USA
Youneng Wang, Columbia University; New York NY USA
Peng Cheng, Columbia University; New York NY -
Y. Lawrence Yao, Columbia University; New York NY USA
Presented at ICALEO 2005

Under single-pulse and multi-pulse modes, the characteristics of copper oxides removal are comparably investigated. A two-dimensional model is utilized to numerically simulate the laser removal process and assist the investigation. In the model, property discontinuity and Stephan and kinetic boundary condition are taken into account, and the moving phase-interface in the material is evaluated with the enthalpy method. Experiments are carried out on copper samples having different oxide film thickness using a Nd:YAG laser with the wavelength of 355nm and the pulse duration of 50ns. The copper oxide film thickness determined by ellipsometer, and the pre- and post-cleaning chemical constituents of the copper oxide film determined via X-ray photoelectron spectroscopy (XPS), are incorporated into the mathematical model. Under the single pulse mode, a higher laser intensity threshold is determined by the model based on the criterion of removing the oxide film as much as possible without damaging the substrate. Under the multi-pulse mode, a lower threshold is employed to remove the oxide layer but the accumulative heat in the substrate under different laser pulse number and different laser pulse repetition rate are the key issues investigated. Reasonable agreement is obtained between the experimental and simulated results.