Bump formation and growth by multiple laser pulses on Ni-P disk substrate

Multiple pulse exposure provides a means for making bumps in the 1-100 nm height range on Ni-P substrates. Although the bump height is generally a nonlinear function of the number of pulses, below the fluence threshold for chemicapillary effects, bump height increases linearly with the number of pulses. At low fluence levels, when the peak melt temperature is below 1400/spl deg/K, the bump surface becomes rough. Avoiding the low fluence regime, this technique can be reliably used for making smooth bumps with flexible shapes and sizes which are useful for tribology studies.