Non-alkyl tin-oxo clusters as new-type patterning materials for nanolithography

Abstract

Nanolithography plays crucial roles in the miniaturization of dense integrated circuit, which extremely depends on innovative resist materials. Recently, metal-containing resists have been explored due to their higher short-wavelength photon absorption than traditional polymer resists. Herein, for the first time, the patterning performance of non-alkyl tin-oxo clusters has been evaluated. Meanwhile, the influence of structural characteristics on resolution and sensitivity has been investigated. To evaluate the surface ligand effect, three non-alkyl Sn 10 -oxo clusters with the same core were functionalized with pyrazole, 3-methylpyrazole and 4-methylpyrazole, respectively. Furthermore, another Sn 14 -oxo cluster with similar core configuration was also prepared using 4-methylpyrazole ligand to study the influence of Sn nuclearity. Spin-coating method was then applied to fabricate thin films of these non-alkyl tin-oxo clusters on Si substrate, which showed various thicknesses and roughnesses. More interestingly, electron beam lithography (EBL) patterning studies indicated that for the same Sn 10 core, the 4-methylpyrazoledecorated clusters showed the best performance. As for the different cluster cores with the same 4-methylpyrazole ligand, the patterns of Sn 10 with the higher ligand:Sn ratio are also better than those of Sn 14 . Finally, distinguishable 50 nm resolution was achieved by 4-methylpyrazole-decorated Sn 10 at expose energy of 100 μC/cm 2 which can be significantly improved by increasing expose energy to 1,000 μC/cm 2 as confirmed by atomic force microscopy (AFM) images. This work not only opens the nanolithography applications of non-alkyl tin-oxo clusters, but also provides an effective structural methodology for improving their patterning performance in future.

A novel stable zinc–oxo cluster for advanced lithography patterning

“…Because of the wide range of metal centers and organic ligands available, the structures and properties of MOCs are highly variable and tunable. 19,20 Among the transition metals with 3d electrons, zinc (Zn)-based MOCs have gained much attention. The absorption cross section 21 of zinc–oxo clusters for 13.5 nm EUV 22,23 is an order of magnitude higher than that of organic polymers.…”

Induced Chemical Networking of Organometallic Tin in a Cyclic Framework for Sub-10 nm Patterning and Interconnect Application

“…Herein, we demonstrate the potential of an organotin-based cage-like network (Sn–CT) as an inorganic resist system for sub-10 nm patterning (Figure ). In general, at the developmental phase, the resists for EUVL are often screened initially with electron beam lithography (EBL) and helium ion beam lithography (HIBL) to evaluate the patterning potential. − ,− …”

“…Recent chip fabrication technology is progressing toward the fabrication of 5 nm node or below with the help of extreme ultraviolet lithography (EUVL) . Hence, the era demands single-nanometer technological nodes which further require suitable resist materials that can print features at sub-10 nm regime through a single exposure, although their development is truly challenging. − In recent times, resist compositions comprising inorganic or organometallic species with resolution potential at the single-nanometer regime and high etch resistance capabilities even with thickness below 20 nm have drawn special attention. − For sub-10 nm patterning applications, it is desirable that the film thickness should be less than 20 nm to avoid pattern collapse. , Also, developing an understanding of the mechanistic aspect of polarity switching of inorganic resist during exposure is an important area as it helps in designing new resist platforms with better performance at a single nanometer regime. − Among various types of inorganic resists, some tin-based compositions are being considered to have the potential to meet the current demand. ,,− In reality, some spin-on type tin-based inorganic resist formulations have been proven to have potential for advanced node applications. , Moreover, as per the recent developments, a few inorganic resists have been shown to have true potential for patterning at a single nanometer regime with a very good pattern profile. − However, the number of such materials is truly limited. Herein, we demonstrate the potential of an organotin-based cage-like network (Sn–CT) as an inorganic resist system for sub-10 nm patterning (Figure ).…”

Organic–Inorganic High-Valence Sn18-oxo Clusters: Direct Utilization of an Inorganic Sn(IV) Source to Improve the Nuclearity and Electrocatalytic CO2 Reduction Properties

“…To form a Sn x O y core, directly introducing inorganic tin sources such as SnCl 4 ·5H 2 O is undoubtedly the most convenient way; however, its rapid and uncontrollable hydrolysis often leads to the formation of tin oxide. Fortunately, very recently, Zhang et al directly used pure inorganic SnCl 4 ·5H 2 O as a precursor, and successfully prepared six nonalkyl TOCs such as Sn 10 , Sn 14 , etc., in which pyrazole and its derivatives were used as both a solvent and a ligand. , Therefore, it is feasible to select ligands and solvents reasonably to realize the controllable hydrolysis of an inorganic Sn­(IV) source and then form an inorganic Sn x O y core to bridge external organotin atoms to construct high-nuclearity tin-oxo clusters.…”