Non-contact nanoparticle removal with laser induced plasma pulses

Abstract

Nanoscale substrate cleanliness is an essential requirement in a variety of nanotechnology applications. The proposed particle removal technique based on pressure shock waves due to laser induced plasma is of interest in various nano/micro-manufacturing applications in which the minimum feature size is reducing rapidly. Any removal method adopted in a manufacturing process must be on the same shrinking feature reduction curve since, for device reliability, the minimum tolerable foreign particle size on a substrate depends on the minimum feature size on a nano/microsystem or device. In the current study, the transient pressure fields exerted on a surface with nanosecond pulse laser generated plasma shock waves are measured using a polyvinylidene difluoride film (PVDF)-based line transducer that was designed and tested for this particular measurement task. Using the pressure data, the corresponding diameters of latex particles that can be removed at these pressure levels are then calculated. It has been shown that latex particles as small as 60 nm in diameter can be removed from silicon surfaces using the nanosecond pulsed laser. Experimental removal data supporting these predictions are also included and discussed.