Improvement in the Sensitivity of PPMMA Electron Beam Resist by S and F Atom Doping

The present work reports the dependence of sensitivity of plasma polymerized methyl methacrylate (PPMMA) as electron beam resist on S and F atom concentration in the films. Plasma polymerization of MMA is carried out in an inductively coupled reactor at different deposition conditions with and without SF6 doping. Ar is used as carrier gas. The bonding characterization of the films is done by IR and X-ray photoelectron spectroscopy (XPS) techniques. XPS data taken on films, deposited under different deposition conditions, is used to estimate the S and F concentrations. The electron beam delineation is done using scanning electron microscope (SEM), modified for electron beam writing. The self development sensitivity of PPMMA films doped with S and F atoms is found to be 2-3 times improved compared to undoped PPMMA and is also dependent on deposition conditions.