Refractive index change and color imaging of acid-chromic polymer films using EB-induced acid generation

Kato, Jun; Yuasa, Kanako; Matsushita, Harumi*; Maekawa, Yasunari; Enomoto, Kazuyuki; Ishii, Tatsuhito*; Ito, Kazuo*; Yamashita, Takashi*

The novel electron beam (EB)-induced color imaging system, consisting of polymer films with acid-responsive chromic molecules (chromic dyes) and EB-acid generators (EBAGs) was proposed. EB irradiation of the acid-chromic polymer films induced acid generation from EBAG, resulting in color formation of the acid-chromic molecules (protonated forms). Nanoscale color imaging on the acid- chromic polymer films was carried out using EB scanning direct drawing. Clear color imaging of 200 nm square and 100 nm line/space patterns could be observed with a dose of only 50 C cm. Furthermore, the large EB-induced refractive index change of these films (0.013 at 632.8 nm) was observed in both TE and TM modes by an m-line method, which is sufficient to create an optical circuit.