Reworkable dimethacrylates with low shrinkage and their application to UV nanoimprint lithography

Abstract

Four types of reworkable dimethacrylates bearing hemiacetal ester groups were synthesized and the UV curing and degradation were studied. UV nanoimprint lithography (UV-NIL) using these monomers was performed and fine line/space patterns were obtained. The shrinkage in height of the UV imprinted pattern was studied in relation to the monomer structure and UV imprint conditions such as light intensity and concentrations of photoradical initiator and chain transfer reagent. The effect of UV imprint conditions on the kinetic chain length of UV cured networks was investigated using size exclusion chromatography of the linear polymers obtained from the degradation of the UV imprinted patterns. A relationship between the kinetic chain length and shrinkage of the UV imprinted patterns was discussed.

Photo-degradation of Reworkable Resin: A Mechanical Study

“…Based on this point of view, we have developed a series of "reworkable" epoxy resins having tertiary ester linkages [5][6][7][8][9][10][11], sulfonate ester linkages [12], and hemiacetal ester linkages [13] as thermallycleavable units. The reactivity, sensitivity, thermal or chemical stability, and re-dissolution property of the polymers must be improved in terms of their practical use.…”

“…Reworkable resins [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], which are thermosets thermally or chemically degradable under a given condition, have been extensively studied as environmentally-friendly materials without damaging the underlying materials. Based on this point of view, we have developed a series of "reworkable" epoxy resins having tertiary ester linkages [5][6][7][8][9][10][11], sulfonate ester linkages [12], and hemiacetal ester linkages [13] as thermallycleavable units.…”

Secondary Patternable UV-Imprinted Reworkable Resin by Additional Photoirradiation

“…UV nanoimprint lithography (UV-NIL) has been extensively investigated due to the fabrication of not only nanopatterning for microelectronics but also functional materials for micro-electro-mechanical systems (MEMS) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. UV-NIL utilizes UV light to cure a photoresist which was pressed using a patterned master mold to obtain the patterned structures.…”

“…Since, in particular, UV-NIL uses UV curable resins, it is almost impossible to remove the cured resins that adhere to the surface of the master mold. We reported a series of "reworkable" resins [13][14][15][16][17][18][19][20], which are thermosets thermally or chemically degradable under a given condition, and applied them to UV-NIL [15][16][17].…”

“…After the acids were generated in the patterns by baking or UV exposure at 254 nm, the sample was dipped in methanol to remove the patterns and a replicated resin mold was obtained on the Si substrate. UV-NIL using the replicated mold was successfully accomplished [15][16][17].…”