Centering Sustainability in Process Development Through Improved Characterization of HFC-PFC Byproducts

Recent legislation concerning the potential regulation of per- and polyfluorinated chemistries as a class (PFAS) has enormous implications for the field of semiconductor manufacturing. This is so because the material foundation of silicon and its dielectrics which prevails across all advanced device technologies dictates the usage of fluorocarbon gases, particularly for subtractive patterning and chamber cleaning processes. Simultaneously, recent progresses in artificial intelligence have spurred large investments in fabrication plants to produce the critical hardware driving that field. As these trends stand in clear opposition to each other, it is increasingly important for synergy between research fields to center sustainability as a key parameter of technological development. The first critical step for such research efforts involves improved characterization of the fluorinated byproducts created in such manufacturing processes. The use of low-temperature plasma discharges tremendously increases the complexity of the available reaction pathways, making this task significantly more challenging. In this paper we present a novel technical analysis method applied to the fluorocarbon polymerization remaining on through-silicon via sidewalls patterned using the Bosch Process. Fluorinated carbon fragments with longer chain lengths than the starting gas precursor molecule were detected, which represents to the best of our knowledge the first time this has been reported in literature. This baseline will be invaluable in future research efforts to assess novel chemistries and abatement treatments.