Zinc-based metal oxoclusters: towards enhanced EUV absorptivity

Abstract

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.

Extreme Ultraviolet-Printability and Mechanistic Studies of Engineered Hydrogen Silsesquioxane Photoresist Systems

“…There have been many alternative resist systems reported for EUV lithography in recent years. Metal-based (Sn, Zn, Hf, Zr, Ti, and others) inorganic systems have gained a lot of attention, especially due to their enhanced EUV sensitivity and smaller molecular sizes. − However, most of them are still in the research and development phase and their patterning data on a commercial EUV scanner is not available. The one standout EUV resist among all has been the Sn-based system developed by Inpria Corporation, which showed a resolution of 13 nm at a dose of 35 mJ/cm 2 …”

Ultrasensitive metal-organic cluster resist for patterning of single exposure high numerical aperture extreme ultraviolet lithography applications

“… – 29 It suggests maskless tools can be used to counter the scarcity of rarely accessible EUV tools to resist developers for screening/prototyping of the futuristic logic nodes resists and low-volume production. The newest, photoresists that enable sub-10 nm, hp resolution to satisfy the stringent requirements of performance and throughput imposed by the aggressive logic device-scaling are limited, even though the EUV ecosystem is ready for HVSM to the chipmakers 30 – 34 In continuation with this, a photoresist must produce patterns with a line width roughness (LWR) of <20%, 35 – 37 which necessitates a higher dose to retain chemical noise and shot noise at a tolerable level originating from the molecular nature of resists formulation and probabilistic interaction behavior of available fewer EUV photons leading to the low-energy secondary electrons (LESEs) generation in the resists dense pattern formation 38 .…”

“…The accomplishment of an expensive EUVL tool inevitably depends on the resists ability to instill the required dense N7+ logic or beyond node patterns. Today, the industry is in search of a novel resist that meets the RLS trade-off for the h-NA∼0.5, EUV tools 17 , 30 – 33 , 40 Furthermore, the size of polymers, thin layer imaging, etch durability, etc., are considered crucial metrics to the sub-10 nm nodes.…”

“…The newest, photoresists that enable sub-10 nm, hp resolution to satisfy the stringent requirements of performance and throughput imposed by the aggressive logic device-scaling are limited, even though the EUV ecosystem is ready for HVSM to the chipmakers. [30][31][32][33][34] In continuation with this, a photoresist must produce patterns with a line width roughness (LWR) of <20%, [35][36][37] which necessitates a higher dose to retain chemical noise and shot noise at a tolerable level originating from the molecular nature of resists formulation and probabilistic interaction behavior of available fewer EUV photons leading to the low-energy secondary electrons (LESEs) generation in the resists dense pattern formation. 38 In unison, the dose should be low enough (≤20 mJ cm −2 ) 39 to enable high throughput chip manufacturing.…”

“…Today, the industry is in search of a novel resist that meets the RLS trade-off for the h-NA ∼ 0.5, EUV tools. 17,[30][31][32][33]40 Furthermore, the size of polymers, thin layer imaging, etch durability, etc., are considered crucial metrics to the sub-10 nm nodes. Additionally, improving the resist material's EUV light absorption is the foremost design requirement for h-NA, EUV resists platforms.…”