Synthesis of UV-curable polycarbonate diols (PCDL)-based polyurethane acrylate for negative photoresist

Abstract

Two kinds of UV-curable polyurethane acrylates (PCDL-H-PUA and PCDL-P-PUA) were synthesized starting with polycarbonate diols (PCDL), isophorone diisocyanate and dimethylolpropionic acid and terminated with hydroxyethyl methacrylate or pentaerythritol triacrylate to impart mono-methacrylate or tri-acrylate end-group functionality, respectively. The structures and properties of the products were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis. The average molecular weights were between 7500 and 9300 g/mol, and the thermal properties of the products were excellent. The influence of the functionality of the end-capping functional group on the UV-curing behavior was investigated using real-time spectroscopy. Results showed that curing rate and conversion of PCDL-P-PUA were higher than those of PCDL-H-PUA, and the final double bond conversion of the polymers reached 95 %. PCDL-H-PUA and PCDL-P-PUA were applied to negative photoresists as the main film resin. The resolution of the optimal photoresist reached 40 lm.

A Realizable Green Strategy to Negative Polyurethane Photoresists through the Application of a Silicone Resin Photoinitiator

“…In recent years, photolithography technology has received growing attention due to its intriguing industrial applications in printing, microelectronic devices, semiconductor materials, integrated circuits, and packaging. − A photoresist is composed of resin, a photosensitizer, solvent, and an additive. The main parameters of photoresists are photosensitivity, resolution, thermal stability, and adhesion to the substrate . According to the chemical backbone of the matrix resin, photoresists are usually divided into a negative one and a positive one.…”

“…Negative photoresists are materials that become insoluble in developing solutions after exposure to UV–vis light. Polymers with cross-linkable groups such as polyacrylamides, cinnamate derivatives, polyethylene glycol acrylates, and acrylic resin derivatives are reported negative photoresists due to their exhibited good solubility, flexibility, ductility, and favorable etch depth. − Polyurethane acrylates (PUA) could be applied as the negative photoresists in photolithographic patterns because of their high photosensitivity and resolution as well as good adhesion to the substrate. ,, Generally speaking, the carboxyl groups are necessary to introduce into the PUA negative photoresists, which could react with alkali and make the polymer soluble in water for pattern development . However, the introduction of carboxyl groups in PUA not only makes the synthetic process become more complex but also makes the recovery of water-soluble polymer difficult after alkali development.…”

“…The main parameters of photoresists are photosensitivity, resolution, thermal stability, and adhesion to the substrate. 6 According to the chemical backbone of the matrix resin, photoresists are usually divided into a negative one and a positive one. Negative photoresists are materials that become insoluble in developing solutions after exposure to UV−vis light.…”

“…7−14 Polyurethane acrylates (PUA) could be applied as the negative photoresists in photolithographic patterns because of their high photosensitivity and resolution as well as good adhesion to the substrate. 6,15,16 Generally speaking, the carboxyl groups are necessary to introduce into the PUA negative photoresists, which could react with alkali and make the polymer soluble in water for pattern development. 6 However, the introduction of carboxyl groups in PUA not only makes the synthetic process become more complex but also makes the recovery of water-soluble polymer difficult after alkali development.…”

“…6,15,16 Generally speaking, the carboxyl groups are necessary to introduce into the PUA negative photoresists, which could react with alkali and make the polymer soluble in water for pattern development. 6 However, the introduction of carboxyl groups in PUA not only makes the synthetic process become more complex but also makes the recovery of water-soluble polymer difficult after alkali development. Furthermore, the lower alkali resistance of the cured polymer films would affect the resolution of pattern.…”