Synthesis of copolymer containing anthracene group and its application in bottom anti-reflective coatings for KrF photoresist

The bottom anti-reflective coating (BARC) can enhance the resolution of nanopatterns in the lithography process. In this work, a series of copolymers P(GA- co -HPMA) containing anthracene group were synthesized using glycidyl methacrylate (GMA), hydroxypropyl methacrylate (HPMA) and 9-anthracene carboxylic acid (ACA) as monomer. The copolymers were characterized by fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance ( 1 H NMR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and ultraviolet absorption (UV–Vis). Next, bottom anti-reflective coatings (BARC) were prepared using P(GA- co -HPMA), p-toluenesulfonic acid (PTSA), highly methyletherified melamine (HMMM) and solvents. The influence of copolymers with different anthracene concentrations was studied on the properties of BARC, and the optimal BARC-4 exhibited commendably low surface roughness and excellent optical performance (n value and k value at 248 nm). At the first minimum film thickness, the reflectivity is reduced to nearly 0 %, making it suitable for use with KrF photoresist.