Formulation optimizations for variable DUV resist thickness applications based on the same polymer matrix

We are investigating strategies of resist optimization for various target thicknesses based on the same polymer. The photo acid generator (PAG) and base levels are optimized for each application thickness. The polymer of choice, used in this work, contained sufficient tertiary-butyl ester groups to provide high dissolution rate after exposure (high Rmax) while its initial dissolution rate in the developer is very low (low Rmin). The polymer structure was also designed to provide a high ratio of carbon to hydrogen atoms to be adequately resistant to plasma etching (1) . Other polymer properties, such as solubility in resist solvents, long shelf life stability, good coating properties, good adhesion to different substrates, low solution viscosity, low coating defects and good wettability are only a few examples of many required characteristics for good resist performance.