Process optimization of a chemically amplified negative resist for electron beam exposure and mask making applications

NEB-22, a chemically amplified negative tone resist has been formulated by Sumitomo for e-beam lithography direct write and mask making applications. The resist has exhibited excellent characteristics which would also make it applicable for use in a SCALPEL exposure tool.(1,2) The initial processing results for Sumitomo NEB-22A5 material demonstrated extremely high resolut ion capabilities with excellent exposure latitude. Although the process wor ked well for many direct write and mask applications, improvements were nee ded to address SCALPEL concerns. The process was modified to maintain sensi tivity and optimize resolution, exposure latitude and FEB latitude. Excelle nt results were obtained in a 200 nm film of NEB-22 with new process parame ters.