Thermal Annealing of Molecular Layer-Deposited Indicone Toward Area-Selective Atomic Layer Deposition

Graphitization of tincone via molecular layer deposition: investigating sulfur's role and structural impacts

This study investigated the synthesis of sp2 carbons using molecular layer deposition (MLD) with tincone, which utilized tetrakis(dimethylamido)tin (TDMASn) as the metal precursor and 4-mercaptophenol (4MP) as the organic linker. Tincone films were deposited at 100 °C without impurities and then subjected to vacuum post-annealing in a tube furnace to induce graphitization. Compositional and structural analyses revealed significant changes as the annealing temperature increased, including the breakdown of the bonds between Sn, O, S, and C. This process led to the reduction of Sn, O, and S and the formation of sp2 carbons. At 400 °C, the film thickness was reduced by 57.5%, and the refractive index increased from 1.8 to 1.97, as confirmed by the emergence of G-band and 2D-band peaks in the Raman spectra. X-ray photoelectron spectroscopy analysis indicated that the residual Sn content decreased to 0.75% at 600 °C. Interestingly, at temperatures above 400 °C, unique behavior was observed: increased C-S bonding disrupted the graphite structure due to the thiol (-SH) groups in 4MP. This disruption led to a reduction in C-C bonding and a decrease in the G-band peak in the Raman spectra. This study provides the first detailed investigation of the role of S in the graphitization of tincone, highlighting its impact on sp2 carbon formation and emphasizing the importance of the careful selection of precursors and linkers in MLD processes.

Facile synthesis of an organic/inorganic hybrid 2D structure tincone film by molecular layer deposition

Organic/inorganic hybrid tincone films were deposited by molecular layer deposition (MLD) using N,N'-tert-butyl-1,1-dimethylethylenediamine stannylene(II) as a precursor and hydroquinone (HQ) as an organic reactant. From previous studies it is known that SnO can be fabricated through a reaction with H₂O, which has low oxidizing power. Similarly, when combined with HQ having a bi-functional hydroxyl group, SnO-based 2D hybrid tincones can be produced. In most aromatic ring-based metalcones described in previous studies, graphitization by pyrolysis occurred during post-annealing. In this study of tincones fabricated with a divalent precursor after a vacuum post-annealing process, the structural rearrangement of the SnO and the benzene ring bonds proceeded to form a SnO-based hybrid 2D structure. The rearrangement of the resulting structure occurred through π-π stacking (without pyrolysis) of the benzene ring. To understand the mechanism of fabrication of 2D hybrid tincones by π-π stacking of the benzene ring and the increase of the crystallinity of SnO after the annealing process, the structural rearrangement was observed using X-ray photoelectron spectroscopy (XPS), grazing incidence X-ray diffraction (GIXRD), grazing-incidence wide-angle X-ray scattering (GIWAXS), and Raman spectroscopy. Thereafter, the design of the crystal structure was investigated.

Dry-Etchable Molecular Layer-Deposited Inhibitor Using Annealed Indicone Film for Nanoscale Area-Selective Deposition

In semiconductor production, the technology node of a device is becoming extremely small below 5 nm. Area selective deposition (ASD) is a promising technique for creating improved overlay or self-alignment, remedying a conventional top-down method. However, the conventional materials and process (self-assembled monolayer, polymer and carbon film fabricated by chemical vapor deposition, and spin coating) for ASD are not suitable for highly conformal deposition. Thus, we investigated a new strategy to deposit conformal films in ASD by molecular layer deposition (MLD). The MLD processes were conducted for an indicone film deposited by INCA-1 (bis(trimethysily)amidodiethyl indium) and hydroquinone (HQ), as well as an alucone film deposited by TMA (trimethylaluminum) and HQ. After thermal heat treatment of the MLD films, variations in thickness, refractive index, and constituent elements of the annealed MLD films were investigated. The indicone film was used as an inhibiting layer for ASD and was etchable with a dry-etching process. The reactive ion etching process on annealed indicone film was optimized according to plasma power, gas concentration, and working pressure. Ruthenium (Ru) ALD was then performed on the annealed MLD films to investigate nucleation delaying cycles and inhibiting properties. A patterned substrate with an MLD/Si line was created via the RIE process, which was allowed to observe the selectivity of the annealed MLD films. In addition, a patterned substrate of SiO₂/annealed indicone/Mo was used to investigate the Ru-selective ALD at the nanoscale. The Ru thin film was selectively deposited on the Mo side-wall surface of a 3D trench structure. The growth of the Ru film was inhibited selectively on an annealed indicone surface of approximately 5 nm.

Effects of Al Precursors on the Characteristics of Indium-Aluminum Oxide Semiconductor Grown by Plasma-Enhanced Atomic Layer Deposition

Atomic layer deposition (ALD) has attracted much attention, particularly for applications in nanoelectronics because of its atomic-level controllability and high-quality products. In this study, we developed a plasma-enhanced atomic layer deposition (PEALD) process to fabricate a homogeneous indium aluminum oxide (IAO) semiconductor film. Trimethylaluminum (TMA) and dimethylaluminum isopropoxide (DMAI) were used as Al precursors, which yielded different compositions. Density functional theory (DFT) calculations on the surface reactions between indium and aluminum precursors showed that while highly reactive TMA would etch In, DMAI with lower reactivity would allow indium to persist in the films, resulting in a more controlled doping of Al. The In/Al composition ratio could be further precisely controlled by adjusting the indium precursor dose time to sub-saturation. IAO based on DMAI was applied to fabricate thin-film transistors (TFTs), showing that Al can be a carrier suppressor of indium oxide. TFTs with PEALD IAO containing 3.8 atomic % Al showed a turn-on voltage of -0.4 ± 0.3 V, a subthreshold slope of 0.09 V/decade, and a field effect mobility of 18.9 cm²/(V s).

Facile rearrangement of molecular layer deposited metalcone thin films by electron beam irradiation for area selective atomic layer deposition

Area selective atomic layer deposition (AS-ALD) is a promising future technology for the realization of a 5 nm scale Si complementary field effect transistor (FET) and its application in industry. AS-ALD is one of the "bottom-up" technologies, which is a key process that can reduce the cost of fabrication and decrease positional error as an alternative to the conventional "top down" technology. We researched an inhibitor for AS-ALD using molecular layer deposited (MLD) films annealed by electron beam irradiation (EBI). We studied the effect of EBI on an indicone film that was fabricated by using bis(trimethylsilyl)amidodiethyl indium (INCA-1), hydroquinone (HQ), an alucone film fabricated by using trimethylaluminum (TMA) and 4-mercaptophenol (4MP). The EBI effect on MLD films was evaluated by investigating the changes in thickness, composition and structure. In order to observe the selectivity of the annealed indicone film, atomic layer deposition of ZnO was performed on the annealed indicone/silicon line pattern, and it was found that the surface of annealed indicone can inhibit ALD of ZnO for 20 cycles as compared to a Si surface.