EUV photolithography: resist progress in metal–organic complex photoresists

J. Micro/Nanolith. MEMS MOEMS

et al. 2019

Background: Hybrid inorganic-organic materials have emerged as promising candidates for EUV resists. However, knowledge on their stability when deposited as thin films is essential for their performance in EUV lithography. Aim: We investigate whether the molecular structure of Zn-based metal oxoclusters is preserved upon thin film deposition and study aging processes of the thin film under different atmospheres, since these chemical changes affect the solubility properties of the material. Approach: A hybrid cluster that combines the high EUV photon absorption cross-sections of zinc and fluorine with the reactivity of methacrylate organic ligands was synthesized. The structural modifications upon thin film formation and after aging in air, nitrogen, and vacuum were studied using a combination of spectroscopic techniques. Preliminary studies on the lithographic performance of this material were performed by EUV interference lithography. Results: The Zn-based compound undergoes structural rearrangements upon thin film deposition as compared to the bulk material. The thin films degrade in air over 24 h, yet they are found to be stable for the duration and conditions of the lithography process and show high sensitivity. Conclusions: The easy dissociation of the ligands might facilitate hydrolysis and rearrangements after spincoating, which could affect the reproducibility of EUV lithography.

Section: Introductionmentioning

confidence: 99%

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

Thakur

Tseng

J. Micro/Nanolith. MEMS MOEMS

et al. 2019

“…Since conventional photoresists based on light elements exhibit low EUV absorptivity, new photoresist materials that incorporate elements with high EUV photon absorption cross‐section, such as metallic elements, are attracting much interest in the EUVL field , . Yet, while the inorganic elements in these materials are considered responsible for the photon capture, the mechanism that leads to the solubility change is mainly determined by the reactivity of their organic components , …”

Section: Introductionmentioning

confidence: 99%

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

Liu

et al. 2019

Eur J Inorg Chem

Metal‐containing molecular hybrid compounds, such as metal oxoclusters (MOCs), are promising materials for extreme ultraviolet (EUV) lithography. The solubility, processability, and reactivity towards EUV photons in these compounds are mostly determined by the composition of their organic shells. Therefore, gaining molecular control on the composition of the shell is crucial to tune their lithographic performance of sensitivity, resolution, and line‐edge roughness. In this work, a new method to prepare MOCs that feature two types of carboxylate ligands is presented. In this method, amine‐functionalized resins are used for the purification step. By using this protocol, Ti‐ and Zr‐based MOCs with mixed‐ligands organic shells were synthesized. The new compounds showed clear differences in the processability and sensitivity as EUV resists compared to their analogues featuring only one type of ligand. The results validate this new synthetic approach for the preparation of custom‐made EUV resists towards better lithographic performance.

“…For adequate lithography performance, resists should simultaneously satisfy resolution (< 10 nm), line-width roughness (LWR < 15%) and sensitivity (dose < 20 mJ/cm 2 ) at sustainable production costs. [3][4][5][6] Though the standard platform for resist materials have been polymer-based chemically amplified resists (CAR's), EUV lithography application demands an entirely new platform for resist development. 3,7,8 As the future process nodes are continuously decreasing, the size of traditionally used polymers in photoresists cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][6] Though the standard platform for resist materials have been polymer-based chemically amplified resists (CAR's), EUV lithography application demands an entirely new platform for resist development. 3,7,8 As the future process nodes are continuously decreasing, the size of traditionally used polymers in photoresists cannot be ignored. In addition, the enhancement of absorption of EUV photons by the resist materials is one of the approaches to optimize their performance.…”

Section: Introductionmentioning

confidence: 99%

Zinc-based metal oxoclusters: towards enhanced EUV absorptivity

Thakur

Extreme Ultraviolet (EUV) Lithography X

Ekinci

et al. 2019

The cost-effectiveness and future progress of EUV (13.5 nm) lithography will largely depend on the resist technology development. Hybrid inorganic-organic photoresists have emerged as promising materials of EUV and have gained increasing attention in recent years. A crucial aspect for hybrid materials is their stability and the preservation of their molecular integrity when deposited as thin films. In this work, we study novel zinc (Zn) oxoclusters as molecular hybrid photoresists. Our aim is to combine the reactivity of methacrylate organic ligands with an inorganic cluster with high EUV photon absorption cross-section arising from this metal. To gain understanding on the shelf life of this material, changes in their structure under different conditions were monitored employing a combination of different spectroscopic techniques. The sensitivity of these oxoclusters under EUV light was investigated and their patterning performance is evaluated using EUV interference lithography. Our results indicate that these novel Zn-based oxoclusters are promising candidates for EUV lithography owing to their high dose sensitivity. Nevertheless, the labile nature of the methacrylate ligands has an important impact in the development process which seems to hamper their reproducibility. This work contributes to the understanding of the pitfalls and advantages of hybrid molecular resists.