Importance of Molds for Nanoimprint Lithography: Hard, Soft, and Hybrid Molds

Table 1

Showing pros, cons, and research improvements for nanoimprint lithography based on hard mold, soft mold, and hybrid molds.

Lithography types	Example	Pros	Cons	Improvements
Hard mold	Silicon, Quartz	High resolution (<100 nm), high chemical stability, high mechanical strength for high aspect -ratio features	Low defect accommodation, high-cost, breakage of the mold during demolding, difficult fabrication process for the working molds	Use of blade for demolding to minimize the breakage of the molds, use of hydrophobic silane layers to coat the molds to avoid accumulation of resist
Soft mold	ETFE, PDMS, PFPE, PET	Generous defect accommodation, easiness of fabricating working molds, flexibility for nonflat surface, high chemical stability, cost-effectiveness	Low resolution (>150 nm), relatively low mechanical strength for high aspect -ratio features	Development of various types of functional polymers in order to enhance the mechanical strength and chemical stability for resolution improvement
Hybrid mold	MINS, Ormostamp, I-UVM-100	Combination of advantages of hard and soft molds	Relatively longer fabrication process compared to soft working molds	Introduction of the hydrophobic silane chain to the molds in order to reduce coating time to avoid resist accumulation