EUV Resist Materials for 16 nm And below Half Pitch Applications

A series of polymer with different hydrophobicity have been synthesized to investigate effects of contact angle on ultimate resolution. Contact angle of these polymers was widely changed by utilizing polymers having a different chemical structure and protection ratio. It is revealed that resolution of 20 nm half-pitch (hp) was limited by pattern collapse and improved by increasing contact angle of polymer under E-beam exposure. It is noteworthy that resolution of 20 nm hp and below for current EUV resists with exposures on a NXE:3100 and a micro-field exposure tool (MET) at SEMATECH Berkeley was also limited by pattern collapse. Low diffusion character of current EUV resists with controlled PAG design, especially polymer bound PAG (PBP), suppressed degradation of resolution by chemical blur. Combination of high contact angle polymer with low diffusivity PAG showed resolution of 16 nm hp using a MET at SEMATECH Berkeley with a LWR of 3.0 nm, sensitivity of 24 mJ/cm2, and Z-factor of 4 × 10-9 mJ nm3. Unfortunately density of blob defect for the hydrophobic polymer was above 100 counts/cm2. Hydrophobicity of film surface was found to be a main cause of its poor defectivity. Adding the new EUV additive to the hydrophobic resist reduced density of blob defect from 100 counts/cm2 to below 0.1 counts/cm2.