COMPARATIVE-STUDY BETWEEN GAS-PHASE AND LIQUID-PHASE SILYLATION FOR THE DIFFUSION-ENHANCED SILYLATED RESIST PROCESS

Surface imaging in combination with dry development has been suggested as a means of overcoming the inherent limitations present in conventional wet develop lithography. The diffusion-enhanced silylated resist process has been demonstrated as one such solution. Silylation is one of the more critical steps in the process, with hexamethyldisilazane being typically used as silylating agent. Alternative gas-phase silylating agents, such as dimethylsilyldimethyl-amine, 1,1,3,3-tetramethyl disilazane and N,N-dimethylamino trimethylsilane, have additionally been studied [Ki-Ho Baik et al., J. Vac. Sci. Technol. B 8, 1481 (1990)]. Liquid-phase silylation holds promise for simplifying the hardware requirements as well as improving silylation properties. Several mono-functional and polyfunctional silylating agents have been investigated. Bis(dimethylamino)dimethylsilane has been found to be promising. N-methyl-2-pyrrolidone was used as diffusion promoter and xylene as the solvent. The influence of solvent composition on the silylation kinetics has been studied. An in-depth study of the silylation process has been performed using both Rutherford backscattering spectroscopy (RBS) and Infrared spectroscopy. Si profiles are measured for liquid- and gas-phase silylation using RBS. A possible mechanism is suggested for liquid silylation. Newly formulated resists as well as the influence of a presilylation bake have been studied.