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.

Ultraviolet Nanoimprint Lithography in the Mixture of Condensable Gases with Different Vapor Pressures

“…We have demonstrated that the rapid bubble-free filling of mold pattern cavities with dimensions ranging from several tens of nanometers (45-nm half-pitch) to several hundreds of micrometers can be accomplished using PFP as the environmental gas in UV-NIL and PAK-01 resins (Toyo Gosei) [18][19][20][21]. Not only is using a PFP atmosphere a potential means to achieve quick and bubble-free cavity filling, but its use is also beneficial as it decreases the viscosity of the UV-curable resin [19], decreases the amount of resin that sticks to the mold during demolding [20], and lowers the demolding forces to approximately onethird of that when performed in air [21]. However, the global warming potential (GWP) 1030 of PFP may prevent its industrial use because of environmental concerns.…”

Uniform Residual Layer Creation in Ultraviolet Nanoimprint Using Spin Coat Films for Sub-100-nm Patterns with Various Pattern Densities

“…UV-nanoimprinted patterns were transferred onto Si by the linewidth evaluation method using extremely shallow Si etching combined with residual layer removal etching. 27) The measured RLT was approximately 20 nm. The etching conditions were as follows: both SF 6 and O 2 gas flow rates of 10 sccm, a chamber pressure of 1.3 Pa, and an RF power of 100 W. The etching time was 15 s, which corresponds to the Si etched depth of approximately 15 nm.…”