Towards novel non-chemically amplified (n-CARS) negative resists for electron beam lithography applications
A novel, non-chemically amplified negative resist was synthesized and characterized for next generation lithography applications. This resist material was shown to be directly sensitive to radiation without utilizing the concept of chemical amplification (CAR) and resulted in high-resolution 20 nm features. This resist design is accomplished by copolymers that are prepared from a monomer containing a sulfonium group which is sensitive to e-beam irradiation. Under 20 keV e-beam imaging and TMAH development, a sensitivity of 2.06 μC cm−2 and contrast of 1.8 were obtained. It has an LER of 20 nm, 10 line pattern varies from 1.8 ± 0.3 to 2.3 ± 0.4 nm.