Area-selective deposition for self-aligned e-beam lithography resist

As the cornerstone of semiconductor manufacturing, lithography drives the miniaturization of nanoscale devices. The solution-processed resists commonly used in lithography face crucial hurdles due to solvent-induced defects, such as pattern collapse and interfacial incompatibility. Although dry resists have emerged as a promising solution, the lack of self-alignment hinders the heterogeneous integration required for next-generation nanofabrication. Here, we report for the first time area-selective molecular layer deposition (AS-MLD) for a poly(methyl methacrylate) (PMMA) dry resist. By exploiting the differences in the lifetimes of plasma-generated radicals, we achieved self-aligned PMMA growth on an electron beam lithography resist (EBLR) surface, while limiting the growth on an Si/SiO₂ surface. The deposition selectivity remained above 97.5%, and the film thickness reached 122.5 nm on the EBLR surface. We found that tuning the process parameters offers control over the thickness from 2.8 Å/cycle to 46.8 Å/cycle, allowing on-demand shrinking for the critical dimension of nanostructures. Moreover, we developed two integrated processes for pattern transfer, demonstrating the versatility of our AS-MLD dry resist.