Mesoscale simulation of molecular resists: The effect of PAG distribution homogeneity on LER

In order to better understand the effects of PAG distribution homogeneity on LER, a mesoscale kinetic Monte Carlo simulation of molecular resists was developed. PAG distribution was controlled by creating random aggregates of PAGs with different sizes. Many common experimentally found defects were recreated in the model simply by increasing the amount of PAG aggregation. LER increases with increasing PAG aggregation for resists with short photoacid diffusion lengths. Increasing the diffusion length helps to smooth out the initial PAG distribution inhomogeneity, but still induces LER through the effect of random diffusion of photoacid outside of the patterned region. PAG aggregation was found to play an important role in LER formation, and affirms that efforts to reduce PAG aggregation and increase PAG distribution homogeneity will likely be critical to meet edge roughness requirements for future ITRS roadmap patterning nodes.