Photodegradable Polyurethane Resist with High Photosensitivity Based on Hexaarylbiimidazole Molecule Photoswitch

As the key material for semiconductor manufacturing, the production technology of a photoresist (PR) is complex, with many varieties and specifications. Therein, the synthesis of current resins and photosensitizers used for the preparation of the i-line photoresist is complicated, and the reaction products may even cause lens pollution. Herein, a kind of photodegradable polyurethane (PU) positive photoresist with a simple system was designed and prepared, in which photocleavable hexaarylbiimidazole (HABI) and tert-butylhydroquinone (TBHQ) were used as a cross-linker and a radical scavenger, respectively. The C–N bond inside the HABI unit was broken under UV irradiation, causing the reversible transformation of HABI into two triphenylimidazole radicals (TPIRs), which were subsequently quenched by TBHQ. Thus, the superpolymer formed an oligomer that could be dissolved in the developer. It was found that HABI-PU PR showed excellent photosensitivity as a positive photoresist during micro–nano manufacturing. The relationship between the content of HABI and TBHQ and resolution and the reaction mechanism between TPIR and TBHQ were studied systematically, and a linear pattern with 1 μm dimension was obtained finally.