Morphology change and release of tin and lead micro-particles from substrates in hydrogen plasma

Extreme ultraviolet (EUV) lithography is a technology for high volume manufacturing (HVM) of integrated circuits. HVM defines critical specification for cleanliness of reticles (masks) used to impose a pattern on wafers. EUV-induced hydrogen plasma produced by photoionization of the H2 gas by the 13.5 nm photons plays an important role in the release and transport of particles from contaminated surfaces to the reticle. It was observed that the rate of particle deposition on the reticle in an EUV scanner scales with EUV power which in turn defines the properties of the EUV-induced plasma to increase the knowledge regarding this phenomenon. We demonstrate images, acquired by a scanning electron microscopy (SEM) to illustrate morphological changes, accumulating in particles of tin, lead and lead oxide that were subject to applied hydrogen plasma (non-EUV). These changes led to the potential loss of adhesion of these materials to the relevant surfaces or potential defectivity outbreaks via explosive fragmentation. This work proposes that the mechanical stress in particles' material lattice caused by accumulation of hydrogen bubbles under the surface plays the major role in the morphological changes observed.