DUV photolithography, as the major process of nanofabrication, typically requires high volumes of toxic chemicals within resist formulation, solvent and developer. In this context, alternative chemistries to current petroleum-derived photoresists are proposed to reduce environmental impacts. Chitosan represents a bio-sourced resist allowing water-based patterning processes free of organic solvent and alkali-based developers, by substitution with a green solvent (deionized (DI) water). This paper present last stepwise process in the patterning integration with a chitosan-based resist. Preliminary results using a 300 mm pilot line scale at CEA-Leti demonstrate patterns resolution down to 800 nm along with plasma etch transfer into Si substrate. Finally, the environmental impact through life cycle analysis (LCA) of the whole process based on chitosan resist is assessed and compared to conventional solvent-based processes.
Biopolymers represent natural, renewable and abundant materials. Their use is steadily growing in various areas (food, health, building …) but, in lithography, despite some works, resists, solvents and developers are still oil-based and hazardous chemicals. In this work, we replaced synthetic resist by chitosan, a natural, abundant and hydrophilic polysaccharide. High resolution sub-micron patterns were obtained through chitosan films as water developable, chemically unmodified, positive tone mask resist for an eco-friendly electron beam and deep-UV (193 nm) lithography process. Sub-micron patterns were also successfully obtained using a 248 nm photomasker thanks to the addition of biosourced photoactivator, riboflavin. Patterns were then transferred by plasma etching into silica even for high resolution patterns.
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