Decomposition of SnH4 molecules on metal and metal–oxide surfaces

Atomic hydrogen cleaning is a promising method for EUV lithography systems, to recover from surface oxidation and to remove carbon and tin contaminants. Earlier studies showed, however, that tin may redeposit on nearby surfaces due to SnH4 decomposition. This phenomenon of SnH4 decomposition during tin cleaning has been quantified for various metallic and metal-oxide surfaces using X-ray photoelectron spectroscopy (XPS). It was observed that the metal oxide surfaces (TiO2 and ZrO2) were significantly less contaminated than metallic surfaces. Tin contamination due to SnH4 decomposition can thus be reduced or even mitigated by application of a suitable metal-oxide coating.