Stochastics in extreme ultraviolet lithography: investigating the role of microscopic resist properties for metal-oxide-based resists

Abstract

Due to the high energy of extreme ultraviolet (EUV) photons, stochastic effects become more important at a constant dose when compared with deep ultraviolet exposures. Photoresists are used to transfer information from the aerial image into physical features and play an important role in the transduction of these stochastic effects. Recently, metal-oxide-based nonchemically amplified resists (non-CARs) have attracted a lot of attention. We study how the properties of these non-CARs impact the local critical dimension uniformity (LCDU) of a regular contact hole array printed with EUV lithography using Monte Carlo simulations and an analytical model. We benchmark both the simulations and the analytical model to experimental data, and then use the flexibility of both methods to systematically investigate the role of microscopic resist properties in the final LCDU. It is found that metal-oxide clusters should be <1 nm in diameter, otherwise granularity will have a significant contribution to LCDU. When varying resist properties to change the resist dose-to-size, we find that the LCDU scaling with dose depends on how the resist is modified. After performing an overall sensitivity analysis to identify the optimum scaling of LCDU with dose, we find a scaling of dose −0.5 when the development threshold is modified, and a scaling of dose −0.33 when core radius or the quantum efficiency is changed.

Stability studies on a sensitive EUV photoresist based on zinc metal oxoclusters

“…2,[10][11][12] Although the standard platform for resist materials has been polymer-based chemically amplified resists, EUV lithography technology requires the development of entirely new resist platforms. 2,[13][14][15] As future nodes are continuously decreasing, the size of polymers traditionally used in photoresists has become a critical point especially with regard to linewidth roughness. 16 Furthermore, increasing EUV light absorption by the resist material is now one of the most important design criteria toward optimizing resist performance.…”

Hybrid EUV Resists with Mixed Organic Shells: A Simple Preparation Method

“…They have well‐defined inorganic cores and organic shells and, as a result of their molecular nature, they are small and have homogeneous (monodisperse) sizes by definition. These aspects contribute to the reduction of stochastic sources that are partly responsible for the “noise” in the nanopatterns, that is, irregularities in the features′ edges (measured as line‐edge roughness) and/or widths (measured as line‐width roughness) …”

Patterning Material Challenges for Improving EUV Stochastics

“…How the material is designed to have high contrast will determine the stochastic defectivity performance. Even for a non-CAR based metal resist, the material granularity will play a role in stochastics defects [27].…”