Damage threshold of substrates for nanoparticles removal using a laser-induced plasma shockwave

Highlights: • The nanoparticles may lead to damage of substrate under the action of laser plasma. • The damage probability of the substrate is closely related to the size of particles. • The break-up and melting of nanoparticles can increase the difficulty of removal. With technological advancement, plasma shockwaves have become widely used as a novel cleaning method to remove nanoparticles. However, insufficient research has been conducted on their cleaning mechanism and application conditions, and the yield strength of substrates has been directly used as their damage threshold. we find that this definition is inaccurate. We treat clean and nanoparticle-coated silicon substrates with a laser-induced plasma shockwave to explore the effects of the presence of nanoparticles on the substrate during cleaning. We have confirmed the effect of nanoparticles on the substrate by simulating the mechanism of temperature and stress propagation between the particles and the substrate. This is because the yield strength of the substrate is greatly reduced by the increase of temperature under the action of shock wave. At the same time, the stress transferred by particles to the substrate increases, resulting in local high-pressure area and pit formation. Moreover, this study finds that the presence of nanoparticles increases the probability of damage to the substrate by an approximate factor of two. And the dependence of the damage threshold of the substrate on the size of the nanoparticles is demonstrated.