Resolution of polymethyl methacrylate: Molecular weights of 950 000 vs 50 000

The work examines the resolution and line-to-line resolution of two molecular weights of polymethyl methacrylate (PMMA), developed in 25%-50% solutions of methylisobutyl ketone in isopropanol. Both PMMA's exhibited similar minimum linewidths of 15-18 nm. Measured linespread functions showed primary Gaussian standard deviations of 11.7 and 28 nm for the 950 and 50 K molecular weight PMMAs, respectively. Developer strength produced less than or equal to 1 nm difference in the width of the linespread function. Atomic force microscope images of latent grating patterns show the same line-to-line resolution for the two undeveloped resists. Developed gratings show the 950 K PMMA to have superior line-to-line resolution. The results are analyzed through integration of the measured linespread functions. (C) 1999 American Institute of Physics. [S0003-6951(99)02726-6].