Novel PAG bound polymers for high resolution EUV applications

As chip feature size continues to shrink, advanced lithographic technology such as extreme ultraviolet lithography (EUVL) has been developed to achieve high quality lithographic performance. In chemically amplified resists (CARs), photoacid generator (PAG) bound polymer (PBP) photoresists have been reported to show superior lithographic performance over the conventional PAG blend polymer photoresists in high resolution EUVL where smaller line width roughness (LWR) and higher sensitivity are both highly desired. The conventional PAG bound polymers are generally synthesized by copolymerization of EUV monomers and PAG monomers. This leads to difficulties to control PBP compositional uniformity and PBP purity level. We have created a new concept to synthesize novel PBPs by polymer functionalization reaction between base polymers and small molecule PAG monomers. This novel synthetic procedure produces PBPs in high uniformity for both monomer and PAG repeating units. These novel PBPs produced by this synthetic procedure have shown smaller line width roughness (LWR) and line edge roughness (LER) in EUVL than the control systems under similar energy doses.