Optimization of Polymer-bound PAG (PBP) for 20nm EUV Lithography

This paper discusses the continued evolution of Polymer-bound PAG [PBP] resists for sub-20nm lithography. Utilizing EUV wavelength, there has been enough progress in resolution and sensitivity to justify the use of these materials. PBP resists have shown that the principal demerit of acid diffusion can be overcome through attachment of the PAG anion to the lithographic polymer. Since the introduction of this chemically amplified resist approach, we have seen steady improvement in resolution, sensitivity, and LWR. Using a 0.30NA EUV tool with dipole, we can achieve 22nm hp resolution, with 12mJ dose, and 4.2nm LWR. Through rational PAG cation design, we have substantially reduced to a factor of 1/10th the PBP resist response to Out-of-Band Radiation compared to a TPS-based PBP. In this way, the resist can act as in situ spectral filter for unwanted longer wavelength exposure.