Synthesis and Solubility Study of the Polyamides Containing 4,4'-(9- fluorenylidene)dianiline in the Backbone as an Antireflecting Spin-on Hardmask Materials

Abstract

Due to the continuous demand for smaller microelectronic devices, there exists a need to reduce the size of structural shapes in microelectronics and other related industries. Toward this end, effective lithographic techniques are essential to achieve a reduction in the size of microelectronic structures. Typical lithographic processes involve etch resistant photoresist underlying materials having antireflecting properties at a certain wavelength exposure. In this work, such materials were synthesized by the step-polymerization of diamines 2,2'-bis(3-amino- 4-hydroxyphenyl)hexafluoropropane (6FP) and 4,4'-(9-fluorenylidene)dianiline (BAFL) with a variety of diacid chlorides [terepthaloyl, isophthaloyl, glutaryl, and succinyl chlorides] and characterized by 1H NMR in tetrahydrofuran (THF-d8), and gel permeation chromatography (GPC) using polystyrene standards. The effect of the structure of the components on the copolymer solubility in mixture of propylene glycol monoethylether acetate (PGMEA) and cyclohexanone used in microelectronics processing was studied by UV-visible spectroscopy. The solubility of the copolymers was found to be in trade-off relationship with BAFL content needed for its antireflective properties and high plasma etch resistance. The polymers that were prepared by using the equimolar mixture of isophthaloyl dichloride and glutaryl dichloride equimolar mixture showed the best solubility, processability and functionality and are applicable as spin-on antireflecting hardmask materials for deep ultra violet (DUV) litfhography technology. They showed good coatability,
chemical resistance, plasma etch resistance, and plasma etch selectivity.