Single-component molecular resists containing bound photoacid generator functionality

Abstract

A series of single component molecular resists were designed, synthesized, characterized, and patterned using 100 keV e-beam lithography. An onium salt PAG based single component system (referred to here as TAS) which creates a free photoacid upon exposure is shown to produce a low line edge roughness (LER) of 3.9 nm (3σ), but was limited in resolution due to photoacid diffusion. A single component molecular resist with a covalently bound non-ionic photoacid generator (referred to here as NBB), i.e. one in which the photoacid anion is bound to the resist core, was found to exhibit an improved resolution of 40 nm due to reduced photoacid diffusion while maintaining a good LER and line width roughness (LWR) of 3.9 nm and 5.6 nm, respectively. Despite the small size of NBB, it was found to exhibit a glass transition temperature of 82°C. It also showed good adhesion, formed high quality films, and showed no dark erosion during development. These compounds demonstrate that it is possible to form single component molecular resists using both ionic and non-ionic photoacid generators and that such small molecule resists can provide all the basic requirements to serve as functional chemically amplified resists.