Development of an inorganic nanoparticle photoresist for EUV, e-beam, and 193nm lithography

Abstract

We have developed a transparent, high refractive index inorganic photoresist with significantly higher etch resistance than even the most robust polymeric resist. As feature sizes continue to decrease, film thickness must be reduced in order to prevent pattern collapse. Normally thinner films prevent sufficient pattern transfer during the etch process, creating the need for a hardmask, thus increasing production cost. Compared to PHOST, we have shown over 10 times better etch resistance. Organic photo-crosslinkable ligands have been attached to a hafnium oxide nanoparticle core to create an imageable photoresist. This resist has shown superior resolution with both E-beam and 193 nm lithography, producing sub-50 nm patterns. In addition to improved etch resistance, the inorganic photoresist exhibits a high refractive index, increasing the depth of focus (DOF). The nanoparticle size of ~ 1-2 nm has the potential to reduce line edge roughness (LER).