Harnessing entropic and enthalpic contributions to create a negative tone chemically amplified molecular resist for high-resolution lithography

Abstract

Here we present a new resist design concept. By adding dilute cross-linkers to a chemically amplified molecular resist, we synergize entropic and enthalpic contributions to dissolution by harnessing both changes to molecular weight and changes in intermolecular bonding to create a system that outperforms resists that emphasize one contribution over the other. We study patterning performance, resist modulus, solubility kinetics and material redistribution as a function of cross-linker concentration. Cross-linking varies from dilute oligomerization to creating a highly networked system. The addition of small amounts of cross-linker improves resist performance by reducing material diffusion and redistribution during development and stiffening the features to avoid pattern collapse. The new dilute cross-linking system achieves the highest resolution of a sensitive molecular glass resist at 20 nm half-pitch and line-edge roughness (LER) of 4.3 nm and can inform new resist design towards patterned feature control at the molecular level.

High Sensitivity Resists for EUV Lithography: A Review of Material Design Strategies and Performance Results

“…Another work of the same group demonstrated a blended resist system with higher performance by combining enthalpic and entropic contributions to solubility contrast. These resists have shown significant advancements in resolution, LER, and processability [76]. Dow electronics designed and synthesized several molecular glasses (MG) resists based on calixarene cores as alternatives to polymeric resists.…”

Recent EUV Resists toward High Volume Manufacturing

“…Blending of NORIA containing oxetane cross-linker and methyladamantyl protected NORIA was examined by Kulshreshtha et al, showing good negative tone resist performance with nBA development as narrow ultimate resolution as 20 nm LS and improved LER compared with the reference without cross-linker derivative [37].…”

Revealing beam-induced chemistry using modulus mapping in negative-tone EUV/e-beam resists with and without cross-linker additives

“…Using advanced high-resolution metrology scanning probe metrology, including PeakForce in combination with observations of patterning quality, we study negative tone resists as a function of cross-linker additives in a Noria based system. [7,8] In this Noria system [9,10], we mix methyl adamantane functionalized Noria (Noria-Mad) with oxetane functionalized Noria (Noria-Ox). The adamantane functionalization acts as an enthalpic dissolution switch such that upon deprotection a carboxylic acid forms which inhibits dissolution in the negative tone developer.…”

“…[7] A variety of techniques including PeakForce Tapping was used to understand changes in resist performance as Noria-Ox increased from 0% to 20% by weight in the mixture. By choosing the appropriate level of oxetane addition, we were able to see significant patterning improvements (resolution and LER) over the pure Noria system.…”