Effective Linewidth Measurement of 45-nm-Half-Pitch Ultraviolet Nanoimprint Lithography Patterns by Scanning Electron Microscope Inspection and Extremely Shallow Si Etching

Abstract

Resist pattern shrinkage during a scanning electron microscope (SEM) inspection is a critical issue in the measurement of the linewidth or critical dimension (CD) of sub-100 nm polymer patterns. For example, the pattern shrinkages were set to 2.3–4.4 nm for half-pitch (hp) 45–90 nm line and space (L/S) PAK-01 patterns fabricated by UV nanoimprint under SEM conditions to diminish pattern shrinkage. We propose an evaluation method of actual CDs of UV nanoimprint lithography (UV-NIL) patterns by extremely shallow Si etching combined with residual layer removal etching. The method was used to conduct stable measurement without any shrinkage problem by transferring patterns fabricated by UV nanoimprint to the Si substrate. Although the linewidth slightly decreased with etching time, we estimated the linewidths just after the residual layer removal for nominal 45, 65, and 90 nm L/S patterns to be 40.3, 55.1, and 72.1 nm, respectively, by combining the widths determined by SEM with the depths determined by AFM. The method enables us to evaluate linewidth more precisely for finer patterns.