ALD/ALE 2026 Session AF-MoP: ALD Fundamentals: Growth and Characterization Poster Session

Recently, amorphous oxide thin film transistors(TFTs) have been widely studied for applications such as wearable electronics, large scale displays, optical sensors and etc., owing to their promising properties: high mobility, uniformity, and good transmittance.[1]

In this work, we developed non-pyrophoric indium precursor (DMITN) and gallium precursor (DMGTN), which are thermally stable and implemented wide atomic layer deposition (ALD) windows. The physical characteristics were investigated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). The non-volatile residues of indium and gallium precursors were about 3.5% and 1%, respectively.

The oxide films (In₂O₃ and Ga₂O₃) were deposited by ALD using O₂ plasma and ozone as oxygen sources. The deposited oxide films were studied via ellipsometer, XPS, XRD, and TEM. In O₂ plasma system, self-limiting growth properties of DMITN and DMGTN were observed 0.9 Å/cycle at 100–250 °C respectively. In particular, the ALD of In₂O₃ film using ozone as an oxygen source was also showed wide ALD window of 250–320 °C and growth rate of 1.0 Å/cycle (Figure 1). In addition, no carbon and nitrogen impurities were detected at all growth temperatures for all films.

The Indium-Gallium-Zinc-Oxide Thin Film Transistors (IGZO TFTs) were fabricated using DMITN, DMGTN, and commercially available for zinc precursor as the n-channel active layer by ALD. The electro-properties of oxide TFTs, compared to oxide TFTs using representative In and Ga precursor, were observed equal or above figures in terms of mobility, threshold voltage, and subthreshold gate voltage swing (Figure 2). The new indium and gallium precursors have demonstrated potential as n-channel active layer materials in oxide semiconductor transistors.

Aluminum phosphate (AlPO₄) is a dielectric material with high chemical and temperature resistance^[1,2] making it suitable for use as a protective coating in lithium-ion batteries^[3,4] and for high-temperature applications.^[5-7] It features a microporous structure of PO₄ and AlO₄^[1] and has been proposed to exist as a stable two-dimensional (2D) bilayer form with inherent, molecular-sized pores and no covalent bonds to its substrate.^[8] With such a structure and high stability, bilayer AlPO₄ could serve as a selective gas-separation membrane. Atomic layer deposition (ALD) is a powerful technique for depositing thin films with high quality, conformality, and precise thickness control, which are essential for achieving the bilayer structure. Utilizing plasma as the co-reactant in plasma-enhanced ALD (PEALD), enables deposition at lower temperatures and provides an additional parameter to modify and control the material composition. For the deposition of ternary materials by ALD, different strategies are viable.^[9] In a previous study, Blomme et al. employed PEALD supercycles of P(NMe₂)₃ and TMA, both with O₂ plasma as the co-reactant, demonstrating the applicability of this approach for the deposition of AlP_xO_y with tunable composition.¹⁰ In this study, we compare two approaches: using a dual-source precursor that introduces both Al and P, versus combining two individual ALD cycles into a supercycle.

We have identified trimethylaluminum triisopropylphosphine (TMAPIP) as a promising dual source precursor with favorable thermal properties (Figure 1a). However, a PEALD process using TMAPIP and O₂ plasma resulted in AlP_xO_y layers with only a few percent P incorporation (Figure 1b), indicating a chemisorption pathway involving the loss of the phosphorous adduct.

In a second approach, in conjunction with density functional theory (DFT) calculations, we developed a supercycle process that combines individual PEALD cycles of trimethylaluminum (TMA) and P(NMe₂)₃ from 60 °C to 240 °C (Figure 2a). This route enables controlled tuning of the AlP_xO_y composition by varying the deposition temperature and supercycle sequence, as shown by Rutherford backscattering spectrometry (RBS) (Figure 2b) and XPS. By combining two P(NMe₂)₃ sub-cycles with one TMA sub-cycle, the deposition of stoichiometric AlPO₄ is achieved (Figure 2c). Using the optimized PEALD process in initial downscaling experiments, we deposited AlPO₄ with an approximate thickness of 3 nm in a continuous, homogeneous thin film, as revealed by transmission electron microscopy (TEM) (Figure 2d). This finding provides a strong foundation for further exploring the bilayer structure of AlPO₄.¹¹

Background. Atomic Layer Deposition (ALD) provides sub-nanometer thickness control and excellent step coverage in 3D device architectures, but ultra-thin films and spatial variability often make single-technique metrology inconclusive.

Approach. We demonstrate a correlative workflow that couples Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) using Quantum Design’s FusionScope AFM-with-SEM platform and the AFSEM®nano AFM insert for Cryo-SEM/FIB systems. SEM is used to rapidly localize thin-film defects (pinholes, particles, seam voids, trench-edge non-uniformity), followed immediately by AFM on the identical region for quantitative height and roughness, plus functional contrast when needed.

Key capabilities. FusionScope enables AFM-SEM-EDS correlation through a shared coordinate system and real-time overlay, minimizing the common “find it again” failure mode in thin-film analysis. Relevant operating ranges include a closed-loop 22 × 22 µm AFM scan with 11 µm Z range and <50 pm imaging noise, alongside a thermal field-emission SEM operated from 3.5–15 kV with pA–nA probe currents under high vacuum. Beyond standard contact/dynamic AFM, advanced modes (e.g., stiffness/adhesion mapping) and interchangeable probes support conductive and magnetic measurements.

In-chamber extension. AFSEM®nano brings closed-loop AFM into existing Cryo-SEM/FIB tools for in situ AFM inside the SEM chamber, with compatibility for nanomanipulators and device biasing. This is particularly valuable on FIB-prepared cross-sections, where sidewall thickness, interfacial roughness, and localized conduction pathways can be mapped at the same coordinates where SEM provides microstructural context.

Outcome. The combined approach shortens the loop between ALD process changes and actionable metrics (step height/thickness, RMS roughness, defect density, stiffness/adhesion contrast, localized conductivity) across planar films and complex 3D semiconductor structures.

Keywords: ALD, correlative microscopy, AFM, SEM, EDS, thin films, failure analysis, 3D semiconductors

High-quality epitaxial growth of nitride thin films remains a critical challenge in conventional low-temperature atomic layer deposition (ALD) due to limited surface kinetics and steric hindrance from precursor ligands. To address this challenge, we introduce a novel strategy referred to as Hydrogen-Manipulated Atomic Layer Epitaxy (HM-ALE), which enables low-temperature epitaxial growth of diverse functional nitride materials at a low temperature of 300 °C by reconfiguring the ALD cycle to precisely control surface reactions at the monolayer scale. For GaN and AlN growth, an H₂ plasma step is introduced prior to N₂ plasma exposure, which mitigates steric hindrance from organic ligands (e.g., methyl groups from TMA or TMG) and enhances adatom mobility and surface reconstruction. This synergistic effect facilitates long-range atomic ordering prior to the reaction with nitrogen species. The ω-2θ XRD patterns demonstrate a pronounced enhancement of the (0002) diffraction signal, while high-resolution TEM images further confirm high-quality epitaxial AlN and GaN films with well-resolved lattice fringes on sapphire substrates. For TiN growth, the HM-ALE method yields low resistivity and high crystalline quality with a well-defined epitaxial relationship and a sharp interface with sapphire substrates as confirmed by high-resolution TEM. Overall, HM-ALE provides a robust low-temperature pathway for epitaxial integration of functional nitrides, ranging from wide-bandgap nitride semiconductors to metallic nitride conductors, and offers new opportunities for nitride-based heterostructures under stringent thermal budget constraints.

Lithium-based batteries are well-known and robust energy storage solutions for portable devices. The widespread electrolyte material employed for microbatteries is a LiPON thin film [1]. It can be deposited by ALD with organic precursors permanently heated into tanks, during several weeks. In this study, the impact of ageing of lithium hexamethyldisilazide (LiHMDS) and diethylphosphoramidate (DEPA) precursors, i.e. the time elapsed in their storage tanks, on their chemical stability is reported. It was already shown that LIHMDS was stable and only DEPA chemically degrades after 14 days of ageing [2].

Three DEPA suppliers, designated by the letters A, B and C, were compared, and significant differences were found, before and after ageing. The as-supplied DEPA purity was identical (98%) for all. However, their ¹H NMR spectra revealed that B and C shared the same structure, which was different for A. After 30 days of ageing at 90°C in a heated tank, significant differences were observed. For supplier A, the powder has agglomerated and turned in brown, whereas it remained white and flowable for suppliers B and C. As shown by FTIR, the brown aged DEPA has lost most of its NH₂ bonds. And ³¹P NMR DOSY experiment has confirmed the agglomeration. When LiPON is deposited with the A DEPA, its ionic conductivity progressively drops over ageing time, with an overall loss of one decade between the as-supplied and the most aged precursor. Since the amine group is known to be involved in the conduction mechanism of LiPON, this is a direct consequence of the amine loss. For suppliers B and C aged in the same conditions, they kept their initial color and texture. Moreover, FTIR revealed that the NH₂ group was no impacted at all by ageing. This different ageing behavior may lie in the composition of the as-supplied products (currently investigated by DSC), or in the starting structure as already evidenced by NMR.

Finally, it is expected that LiPON deposited with DEPA from suppliers B or C, will not show any deleterious impact on its ionic conductivity (in progress).

[1] Sallaz et al, 2024, https://doi.org/10.1021/acselectrochem.4c00022

[2] Massoni et al, 2025, ALD/ALE 2025, talk #AA2-WeA-12

HfO₂ thin films were deposited by thermal atomic layer deposition (ALD) using a thermally stable cyclopentadienyl-based hafnium precursor (CpHf) and comparatively evaluated as a function of oxidant chemistry (H₂O vs O₃) for charge-trap memory (CTM) applications. Deposition was carried out on a 300 mm single-wafer ALD system (Atomic Premium, CN1 Co., Ltd.) at 320 °C and 0.45 Torr. GPC and RI were extracted by systematically varying precursor/oxidant pulse and purge times to establish optimized process recipes. For the H₂O process, saturated growth was achieved with CpHf 1 s and H₂O 1 s, and film uniformity significantly enhanced when purge times were increased to 20 s, yielding an average GPC of 0.058 nm/cycle and RI of 2.00. For the O₃ process, growth stability improved with longer O₃ exposure; the optimized recipe (CpHf 1 s / purge 20 s / O₃ 5 s / purge 20 s) exhibited a higher average GPC of 0.068 nm/cycle with RI of 1.99. CTM capacitors with a Si/SiO₂ (2 nm)/HfO₂ (10 nm)/Al2O3 (10 nm)/Au stack were fabricated and post-deposition annealed at 350, 400, and 450 °C. X-ray diffraction showed no crystallization of either Al₂O₃ or HfO₂ for all anneal temperatures.

Electrically, O₃-processed devices exhibited larger C-V memory windows than H₂O-processed devices under identical measurement conditions, with the largest difference after 350 °C annealing. Fowler–Nordheim analysis and constant-current stress indicated relatively minor degradation at 350 °C, the H₂O process yielded an overestimated apparent barrier suggesting defect-induced mixed conduction, whereas the O₃ process retained linear FN behavior consistent with dominant FN tunneling. Endurance cycling confirmed stable memory windows of ~6.0–6.2 V over 10¹–10⁴ cycles for O₃-based devices, while H₂O-based devices degraded from 0.823 to 0.691 V. Overall, O₃ is a more favorable oxidant for CpHf-based HfO₂ ALD, improving both process efficiency (GPC) and CTM memory characteristics (window and endurance).

Aluminum nitride (AlN) is an ultra-wide-bandgap semiconductor (6.2 eV) with applications in optoelectronics and high-power electronics due to its high thermal conductivity, low thermal expansion coefficient and high dielectric strength. Conventional deposition techniques for high-quality AlN, such as metal-organic chemical vapor deposition and molecular beam epitaxy, typically require temperatures exceeding 700 °C, limiting integration with temperature-sensitive materials and pre-existing layers.

In this work, we demonstrate the deposition of single-crystal AlN films on gallium nitride (GaN) templates at a substrate temperature of 300 °C using plasma-enhanced atomic layer deposition (PEALD), without additional energetic plasma exposures or ex situ annealing. The deposition was carried out in an Ultratech Fiji G2 PEALD system on c-plane GaN-on-sapphire substrates. Prior to growth, the substrates were exposed to a remote N₂–Ar plasma to condition the surface. Each PEALD cycle consisted of a trimethylaluminum (TMA) precursor pulse followed by a remote N₂–Ar plasma co-reactant step under low-pressure conditions optimized for epitaxial growth.

High crystalline quality is evidenced by narrow X-ray diffraction rocking curves of 288 arc sec (0.08°) for 10 nm films and 497 arc sec (0.138°) for 70 nm films. Continuous epitaxial growth across the full film thickness is confirmed by high-resolution transmission electron microscopy and selected-area electron diffraction. Atomic force microscopy reveals smooth surface morphologies with sub-nm roughness.

This research demonstrates a PEALD-based approach for achieving high-quality, single-crystal AlN films at 300 °C, enabling III-nitride integration into low-thermal-budget platforms without additional in situ energetic plasma exposure or ex situ annealing steps that may degrade film quality.

This presentation discusses the results published in Ref. [1].

[1] Pini Medved, Silvia Piperno, Valentina Korchnoy, Gili Cohen-Taguri and Asaf Albo, “Low-temperature high-quality epitaxial AlN films deposited by PEALD,” Appl. Phys. Lett., vol. 127, no. 23, 232104, Dec. 2025, doi: 10.1063/5.0291492.

This work was supported by the Israel Science Foundation (Grant No. ISF 1755/23) and by the Israel Ministry of Science and Technology (Grant for Proposal No. 0007465).
The work is the subject of a pending U.S. patent application (No. 63/844,832).
The first author gratefully acknowledges support from Ariel University through a Ph.D. scholarship.

Correspondence should be addressed to: asafa@ariel.ac.il

Metal (M) phosphates are compatible with diverse applications that span battery technology, corrosion protection, electrocatalysis, and proton conduction. Phosphate polymorphs have multiple structures and stoichiometries, with the P/M ratio profoundly impacting their functional properties and applicability [1]. Atomic layer deposition (ALD) of metal phosphate films commonly combines metal oxide (MO) and phosphorus oxide (PO) cycles in supercycles. Trimethylphosphate (TMP) is the most-used P source for ALD, combined with H₂O, O₃ or O₂ plasma as oxidants [1-3].

In this work, we first investigated the ALD growth of PO using alternating TMP and O₂ plasma exposures. In-situ spectroscopic ellipsometry (iSE) and in-situ reflection Fourier transformed infrared (FTIR) spectroscopy revealed self-inhibited growth – an initially high growth on oxide surfaces, followed by rapid saturation with continuing film growth (Figure 1(a)).

Next, we developed a new plasma-enhanced ALD supercycle to grow zinc phosphate (ZnPO) films by combining one ALD cycle each of ZnO (DEZ/O₂ plasma) and PO (TMP/O₂ plasma) at 150 °C. The process demonstrated self-limiting film growth and resulted in the deposition of P-doped ZnO films, with improved (compared to [4]) but limited P incorporation of ca. 11 at.% (Figure 1(b)).

Increasing the number of PO cycles (n) from 1 to 5 in the [1·(ZnO) – n·(PO)] supercycle improved the P incorporation in the films, whose composition varied from P-doped ZnO to zinc metaphosphate (ZnPO₃) (Figure 2(a)). Our data also suggested that the PO interlayers impact the long-range order of ZnO layers within the as-deposited films, impacting their crystallinity (Figure 3(g)). However, we observed concurrent reduction in both the growth per supercycle (GPSC) as well as elemental Zn and P incorporation for the films for n > 3 (Figure 2(b,c)).

Experimental and computational data elucidated the dependence of film growth on the composition of the growth surface. ZnO growth is suppressed on a PO surface, resulting in self-inhibited film growth for the supercycle. This self-inhibited growth, in combination with nucleation effects for ZnO ALD on PO surfaces, results in the deposition of increasingly rough films, as n increases (Figure 3(a–f)). Overall, this work highlights the need to consider the interactions between the precursors and growth surfaces during the development of similar ALD supercycles for other metal phosphate families.

[1] Henderick et al., Appl. Phys. Rev., 9, 011310 (2022)
[2]Hornsveld et al., J. Phys. Chem. C., 124(9), 5495 (2020)
[3]Di Palma et al., J. Vac. Sci. Technol. A, 38, 022416 (2020)
[4]Tynell et al., J. Mater. Sci., 48, 2806 (2013)

Plasma enhanced atomic layer deposition (PEALD) is a key technique for the low temperature fabrication of conformal, high quality thin films used in semiconductor, photonic, and MEMS technologies. In microwave driven PEALD systems, magnetic fields are commonly employed to stabilize the plasma and tailor electron density. However, these fields may unintentionally magnetize magnetic or magnetically sensitive substrates, limiting the applicability of the process for advanced device architectures [1,2]. Recent reviews of ALD process engineering have emphasized the importance of reactor design, plasma configuration, and substrate specific constraints, including magnetic sensitivity, when targeting precision thin film properties in industrial ALD platforms [3].

In this work, a non-magnetizing microwave PEALD approach for Al₂O₃ thin films is demonstrated in a batch processing tool enabling simultaneous double-side wafer deposition with excellent conformality and coverage on both sides. A dedicated magnetic shielding concept was developed specifically for this batch architecture, where magnetic neutrality and highly uniform film properties across both wafer surfaces are critical. Three-dimensional magnetic field simulations were used to guide the design of a magnetic absorber, systematically evaluating the influence of shield size, aperture geometry, and distance to the substrate on the magnetic flux density at the sample position. The finalized shielding concept was implemented directly into the PEALD reactor without compromising plasma ignition or stability.

Magnetic field measurements confirmed that the shielding reduced the magnetic field at the substrate position below the magnetization threshold of sensitive materials, preventing permanent substrate magnetization during plasma exposure. Subsequently deposited films exhibited excellent thickness uniformity on each side of each substrate, stable refractive index, and strong wafer to wafer reproducibility.These results establish a viable route for non-magnetic PEALD processing in microwave plasma environments and provide a framework for integrating magnetic field mitigation strategies into industrial ALD systems for sensitive applications.

References:

[1] George, S. M. Atomic Layer Deposition: An Overview. University of Pennsylvania.
https://www.seas.upenn.edu/~nanosop/documents/overviewofALD.pdf

[2] Li, H.; Knez, M.; et al. Influence of Magnetic Field on the Reaction Mechanisms of Plasma-Assisted Atomic Layer Deposition of Al₂O₃.Surface and Coatings Technology.
https://www.sciencedirect.com/science/article/pii/S0257897217311478

[3] Profijt, H. B.; Potts, S. E.; van de Sanden, M. C. M.; Kessels, W. M. M. Advances in Atomic Layer Deposition. Journal of Vacuum Science & Technology A, 2011, 29 (5), 050801.

Magnesium–containing thin films—including magnesium oxides, magnesium fluoride, magnesium nitrides, and magnesium–doped GaN/ZnO—are useful for energy storage, electrical insulation, and optical coatings. Cyclopentadienyl–magnesium precursors (Mg(RCp)₂) are widely used in deposition studies because they are highly volatile, thermally stable, and strongly reactive toward co–reagents. However, most of these manganocene compounds are pyrophoric, making them difficult to store and handle. The present study describes the synthesis of magnesium cyclopentadienyl amine adducts, which mitigate the pyrophoricity of the parent compounds while maintaining desirable precursor characteristics.

Here, we describe the synthesis of amine adduct of magnesium cyclopentadienyl complexes, Mg(MeCp)2TMEDA (1), Mg(MeCp)2TEEDA (2), Mg(MeCp)2TMPDA (3), Mg(MeCp)2TMBDA (4), Mg(EtCp)2TMEDA (5), Mg(MeCp)2TEEDA (6) (Fig. 1). Pure complexes 1-6 were obtained by sublimation at low vacuum. Purity and structures were confirmed by 1H NMR, 13C NMR, and X-ray crystallography. Thermal behavior and volatility of complexes was investigated by TG and DSC. Compound 1-6 showed clear evaporation with <0.5% residue after 200 ̊ C (Fig 2). Preliminary air-exposure testing indicated that none of the compounds exhibit spontaneous ignition when exposed to air. Overall, complexes 1–6 exhibit promising properties as precursors for magnesium–containing metal depositions, and their reduced pyrophoricity relative to the parent compounds offers clear advantages for safer storage, transfer, and handling.

Lingam, H. K.; Arachchige, A. A.; Roberts, D. A. Amine adduct of group 2 metallocene precursors for deposition of group 2 metal films for Ereztech Labs. US. Pat. Appl. US 2025/0353865 A1, 2025.

Ozone (O₃) is investigated as a co-reactant with trimethylaluminum (TMA) for atomic layer deposition (ALD) of Al₂O₃ on ZnOnanopowders, producing core-shell powders subsequently densified into ceramics. O₃ is explored as an alternative to H₂O due to the propensity of moisture to form capillary bridges in nanoparticle beds, leading to strong interparticle cohesion, reactant retention, and non-ideal ALD behavior including parasitic chemical vapor deposition-like growth and powder agglomeration.1Minimizing agglomeration is critical because the Al₂O₃ coating is intended to act as a diffusion barrier that suppresses ZnOgrain growth during sintering for nanocrystalline ceramic fabrication.

Nanoparticle beds exhibit high specific surface areas (18 m² g⁻¹ in this study), resulting in ALD processes that are transport-limited within the powder bed. Consequently, extended exposure and purge times are often required for half-reactions to approach saturation, presenting challenges for scalable powder coating.

In this work, the effects of reactor temperature and powder mass loading on O₃-based ALD kinetics are examined using a rotary powder ALD reactor. ZnO nanoparticle loadings of 0 g (empty reactor), 1 g (18 m2), 3 g (54 m2), and 6 g (18 m2) are studied at temperatures of 120 °C, 175 °C, and 250 °C. Reaction progress is monitored in situ using a quadrupole mass spectrometer (QMS) residual gas analyzer (RGA) to track gas-phase reactant consumption and reaction by-products during each half-cycle. Powder surface area before and after coating is measured using the Brunauer–Emmett–Teller (BET) method.

Across all temperatures and powder loadings examined, QMS-RGA signatures associated with the TMA half-reaction exhibit progressively shorter saturation times with increasing ALD cycle number. BET measurements indicate no appreciable change in total surface area following coating. Taken together, these observations suggest a progressive reduction in the density or accessibility of reactive surface sites during cycling, consistent with incomplete surface regeneration during the O₃ half-reaction under the conditions studied. These effects are attributed to transport limitations and/or rapid recombination of ozone-derived oxygen species within the nanoparticle bed, which may hinder full restoration of reactive sites between cycles.

This work demonstrates that while O₃ effectively mitigates moisture-induced agglomeration in nanoparticle ALD, its transport and reaction characteristics can limit surface renewal in highsurfacearea powder systems, thereby constraining its effectiveness as an oxidant for conformal coating of dense nanoparticle beds.

As DRAM devices continue to scale down, dielectric materials that can simultaneously provide a high dielectric constant and low leakage current are required to secure sufficient capacitance within a reduced cell area. In metal–insulator–metal (MIM) capacitor structures employing TiN bottom electrodes, oxygen scavenging by TiN induces interfacial degradation, leading to increased oxygen vacancy formation in adjacent oxide dielectrics and consequent degradation of electrical reliability. Although TiO₂ has been widely investigated as a high-k dielectric candidate, its relatively small band gap and unstable interface with TiN limit its applicability in single-layer configurations.

In this study, a ZrO₂/TiO₂ stacked dielectric structure incorporating a ZrO₂ buffer layer between the TiN bottom electrode and the TiO₂ dielectric is proposed to alleviate interfacial degradation and suppress leakage current. Electrical characterization revealed that TiO₂ single-layer capacitors exhibited pronounced DC nonlinearity and increased leakage current due to poor interfacial properties at the TiN/TiO₂ interface. In contrast, the introduction of a ZrO₂ buffer layer significantly reduced dielectric loss and leakage current, resulting in improved capacitance stability. Chemical analysis confirmed that the ZrO₂ buffer layer effectively suppressed oxygen scavenging from the TiN electrode, thereby reducing oxygen vacancy formation in the TiO₂ layer and enhancing interfacial stability.

Furthermore, recrystallization induced by the oxide top electrode was utilized to enhance the dielectric constant. When sufficient thickness was provided, the ZrO₂ and TiO₂ films were well crystallized into tetragonal-ZrO₂ and anatase-TiO₂ phases, respectively. As the TiO₂ thickness decreased, a localized phase transformation from anatase to rutile TiO₂ was induced at the interface with the oxide top electrode, contributing to an enhanced dielectric constant. Systematic variation of the ZrO₂/TiO₂ thickness ratio revealed a trade-off between dielectric constant and leakage current, with thicker ZrO₂ layers providing superior leakage suppression. In particular, a ZrO₂ buffer thickness of 7 nm or greater was found to be effective in achieving low leakage characteristics while maintaining an enhanced dielectric response.

These results demonstrate that the ZrO₂/TiO₂ stacked dielectric architecture, in which TiO₂ thickness is controlled to realize mixed anatase–rutile phases, is a promising dielectric design for next-generation TiN-based DRAM capacitor applications.

The gate dielectric oxide film (e.g. HfO₂) for FET requires low impurity levels and excellent electrical properties. ALD enables the deposition of high-quality gate oxide films, and O₂ plasma, which generates highly reactive atomic oxygen (O radical), has been widely used. However, recent FET devices have become increasingly stacked (e.g., GAA), gate dielectric films must be deposited deep into nanometer-scale microfabricated trenches exceeding an aspect ratio of 100.O₂ plasma ALD cannot deposit the HfO₂ film inside trenches with aspect ratios over 50 due to the deactivation of O radical within trench diffusion[1]. We have reported the high quality of Al₂O₃ film properties by ALD using pure ozone gas (PO-ALD), which is high-concentration pure ozone gas (≥80 vol%) as the oxidizing source and reported the Al₂O₃ film can be formed in trenches with high aspect ratio( > 1500) [2], while cannot deposit with low aspect ratio (<100) using O₂ plasma[1]. Furthermore, it was reported that highly reactive OH radicals can generate by mixing water vapor with high-purity ozone gas at 250°C[3]. This presentation discusses the effect of using OH radicals as an ALD oxidation source on the film quality of HfO₂ films.

Figure 1 shows the schematic ALD chamber and gas piping systems. The distribution of the gas phase temperature inside the chamber by a hot wall method is controlled to under 100°C upstream of the substrate, and to substrate temperature (>150°C) of the downstream the substrate. These temperature distribution is the generation of atomic oxygen near the substrate through the thermal decomposition reaction of ozone (O₃→O₂+O).By supplying a mixed gas of ozone and water vapor under these temperature conditions, the ozone thermally decomposes near the substrate, generating O, which then reacts with H₂O to generate OH radicals, which can then be supplied to the substrate (see Fig. 2). Gas supply conditions for ozone and water vapor (flow rate mixture ratio, etc.) are determined by increasing ahing rate at the substrate position due to the supply of OH radicals. Precursor and carrier gases are TDMAH(((CH₃)₂)₄Hf) and Ar, respectively. Figure 3 shows the relationship between the number of ALD cycles and HfO₂ film thickness at a substrate temperature of 200°C. The introduction of water vapor slightly increases the film thickness. The estimated GPC are 0.138 nm/cycle(with water vapor) and 0.126 nm/cycle (w/o water vapor), respectively. We will report on film quality, including a comparison of impurity levels in the film, using SIMS and XPS.

[1]K. Arts, M. Utriainen, R. L. Puurunen, W. M. M. Kessels, and H. C. M. Knoops, J. Chem. C 123 27030 (2019).

[2] S. Motoda, T. Hagiwara, N. Kameda, K. Nakamura, and H. Nonaka, ALD/ALE 2023 Poster presented at AF-MoP-10 (2023).

[3] N. Kameda, K. Uehara, S. Yasuhara, S. Motoda and T. Nishiguchi, ALD/ALE 2025 Poster presented at AF-MoP-7 (2025).

Atomic layer deposition (ALD) of ZnO is most commonly based on the diethylzinc (DEZ)/H₂O process, which offers high reactivity and excellent film quality but is associated with significant safety risks due to DEZ's pyrophoric nature. In this work, we systematically evaluate three alternative zinc precursors—bis(3-(N,N-dimethylamino)propyl)zinc(II) (Zn(DMP)₂), bis(N-(2-ethoxyethyl)-2-penten-2-on-4-iminate)zinc(II) (Zn(EEKI)₂), and ethyl(di(trimethylsilyl)amido)zinc(II) (ZnEt(HMDS))—and benchmark their performance in thermal ALD against DEZ using water as the sole co-reactant.^[1]

All four precursors exhibit self-limiting ALD behavior and facilitate the deposition of high-quality ZnO thin films at a common growth temperature of 200 °C. In-situ spectroscopic ellipsometry reveals distinct precursor-specific growth mechanisms, including variations in adsorption behavior, ligand desorption during purge steps, and ligand removal during the water half-cycle. While DEZ shows signatures of partial thermal decomposition, the other precursors retain more intact surface species with steric differences leading to variations in growth per cycle (0.8–2.3 Å) and surface morphology.

Comprehensive ex-situ characterization (XPS, RBS/NRA, AFM, TEM, XRD, and UV/Vis spectroscopy) confirms that all processes yield dense, polycrystalline, near-stoichiometric ZnO films with similar crystallinity and optical band gaps. However, notable differences in surface roughness and nucleation behavior are observed, especially for the bulkier ligand systems Zn(EEKI)₂ and ZnEt(HMDS). Importantly, ZnEt(HMDS) enables a previously unreported thermal ALD process with a growth rate comparable to DEZ, while avoiding its extreme pyrophoricity.

These results clearly demonstrate that alternative zinc precursors can deliver ZnO thin films of similar quality to DEZ while providing advantages in safety, growth chemistry, and process flexibility. Expanding the zinc precursor library is therefore an important step toward more robust ALD process design, especially for complex multicomponent oxides and advanced device architectures.

References

[1] J. Obenlüneschloß, R. Pathak, V. Rozyyev, A.U. Mane, T. Gemming, D. Rogalla, J.W. Elam, A. Devi, “Expanding the Zinc Precursor Toolbox: A Comparative Study of Precursors for Thermal ALD of ZnO Thin Films” Dalton Trans. 2026, accepted and in print.

Vanadium oxide (VO_x) exhibits structure and electrical properties that strongly depend on its oxidation state and crystal structure, making precise control over high-quality thin-film formation critically important. Atomic layer deposition (ALD) enables atomic-scale control of film thickness and composition, offering excellent compositional uniformity and process reproducibility. However, conventional vanadium precursors suffer from limited thermal stability, which restricts the maintenance of self-limiting deposition behavior at temperatures above 200 °C.

In this study, VO_x thin films were deposited by an ALD process using a thermally stable vanadium precursor at deposition temperatures ranging from 150 to 320 °C, and their structural and electrical properties were systematically investigated. At 250 °C, the VOₓ films crystallized from an amorphous phase into polycrystalline V₂O₅, with the fraction of the high oxidation state V⁵⁺ increasing as the deposition temperature increased. In contrast, at 320 °C, partial reduction occurred due to oxygen deficiency induced by the high-temperature process, resulting in an increased contribution of the V⁴⁺ component. The resistivity of the VO_x films grown on SiO₂ substrates was found to be within the bulk V₂O₅ values reported in the literature. These results demonstrate that a thermally stable precursor–based ALD process enables post-treatment-free control over the crystallinity and electrical conductivity of VOₓ thin films.

"Black" titanium dioxide (TiO_x<2) has attracted significant attention for photocatalytic and energy storage applications due to its reduced bandgap and high concentration of active Ti³⁺ surface defects. Conventionally, generating these specific defects requires harsh post-treatments like high-pressure hydrogenation. In this work, we improve on a direct, low-temperature Atomic Layer Deposition (ALD) route to synthesize and tune black TiO_x films by exploiting the specific precursor kinetics of the TDMAT/H₂O process [1, 2, 3].

We hypothesize that the concentration of Ti³⁺ defects and consequently the resulting crystal phase can be precisely controlled by manipulating the precursor pulse duration. Using a process temperature of 200 °C, we show that variations in the pulse length allow for the targeted synthesis of specific defect environments.

Preliminary analysis reveals that this defect engineering directly dictates the polymorph stability upon annealing, enabling a tunable shift between anatase- and rutile-dominated modifications. To distinguish between self-limiting ALD growth and parasitic CVD-like decomposition as the origin of these defects, we correlate the structural evolution (GIXRD) with growth rates (GPC) and surface morphology (AFM).

Our results present a novel "kinetic knob" to tailor the stoichiometry and electronic properties of black TiO_x without changing the thermal budget, offering new pathways for defect-enabled functional coatings.

References

[1] J. Saari et al., J. Phys. Chem. C 2022, 126 (36), 15357-15366

[2] J. Saari et al., J. Phys. Chem. C 2022 126 (9), 4542-4554

[3] J. L. Vazquez‐Arce et al., Adv. Mater. Interfaces 2024, 11, 2400269

Atomic layer deposition (ALD) of noble metals such as platinum (Pt) is increasingly relevant for advanced device applications, yet remains challenging due to high precursor cost, narrow process windows, and limitations of conventional metrology for assessing conformality in high aspect ratio (HAR) features. In this work, we present the first demonstration of combined conformality and electrical characterization of Pt ALD films using the electrical test structure patterning enabled by PillarHall technology. The structure is based on pillar-stabilized large-area membrane that can be selectively removed by tape lift-off after the deposition. This membrane removal leaves controlled narrow line of thin film with probe/solder pads at each end, enabling direct electrical contacting without additional processing.

Pt thin films were deposited in a thermal ALD reactor (Picosun R100) using MeCpPtMe₃ and O₂ at 300 °C, based on a process previously optimized for planar substrates [1]. To enable reliable electrical probing while minimizing disturbance to the ALD process a thin dielectric precoating of 5 nm Al₂O₃ was introduced on top of the native oxide. Film thickness and conformality were evaluated optically using ellipsometry. For Pt thicknesses up to 25 nm, changes in optical parameters are sensitive to film growth, enabling thickness measurement along the lateral high aspect ratio (LHAR) channel. Beyond this range, ellipsometric response saturated, highlighting a fundamental limitation of optical metrology for thicker metallic films. In parallel, four-probe resistance measurements were performed on the same LHAR5 chips, enabling direct correlation between electrical properties and film thickness. The measured resistance followed the expected thickness dependence, increasing with decreasing Pt thickness, while temperature-dependent measurements showed metallic behavior, with resistance increasing with temperature in the range 100-400 K.

The current research demonstrates that the LHAR5 electrical test structure provides a controlled and robust platform for studying highly conductive films, enabling reliable measurements over wide temperature ranges and penetration depths. The methodology provides a practical route to study noble metal ALD processes in HAR structures and opens pathways for future work combining electrical, optical, and nanoscale characterization, including AFM-based conductivity mapping and SEM/EDS analysis.

References

[1] R. Ghiyasi, G. C. Tewari, and M. Karppinen, Tunable Electrical and Optical Properties in Atomic Layer Deposited TiO2:Pt Thin Films via Dynamic Metallic Nanoparticle Formation, Adv. Mater. Interfaces, 2025, e00594.

Self-assembled monolayers (SAMs) are organized films that spontaneously form when molecules attach to a surface and arrange into ordered structures. SAM assembles and the modification of the surface are determined by the nature of the surface-binding group, the architecture of the backbone, and the terminal functionality. The molecule-surface interaction has a profound impact in areas such as molecular electronics and protective coatings. Carboxylic acids, thiols, silanes, phosphonic acids, and carbenes have been widely used for SAM coatings, while limited effort has been directed toward exploring alternative surface ligands, especially those based on inorganic scaffolds. The phosphaza-bicyclo[2.2.2]octane core is symmetrical and contains P(III) centers at axial positions within a rigid three-dimensional architecture. Its modular synthesis enables control over volatility and reactivity while preserving a chemically robust framework. We have establishedP₂N₆ as a new molecular platform for SAMs. By demonstrating deposition and selective adsorption on metals, we reveal the ability for monolayer formation that expands the precursor design space for deposition processes. This represents the first time that resilient, P-based SAM has been identified. Details of careful quartz crystal microbalance (QCM) experiments, molecular layer deposition (MLD) processes and scanning tunneling microscopy results will be presented.

In recent years, extensive research has been conducted on application of doped-HfO₂ as high-k dielectric materials in advanced electronic devices such as dynamic random-access memory (DRAM), ferroelectric field-effect transistors (Fe-FETs), and ferroelectric junction transistors (FJTs). Among these materials, ZrO₂-doped HfO₂, specifically Hf₀.₅Zr₀.₅O₂ (HZO), has attracted significant attention as a promising alternative dielectric for DRAM capacitor applications. HZO exhibits various crystalline phases depending on dopant concentration and thermal conditions, including the tetragonal phase with a high dielectric constant and the non-centrosymmetric orthorhombic phase, which is associated with ferroelectric behavior. In this study, HZO thin films were deposited using an atomic layer deposition (ALD) process with Cp-based Hf and Zr precursors at low temperatures ranging from 250 to 350 °C. The morphological characteristics and thickness uniformity of the deposited HZO films were evaluated using atomic force microscopy (AFM) and X-ray reflectivity (XRR). The crystalline structure and phase distribution were analyzed by X-ray diffraction (XRD), while the microstructural features and interfacial properties were further investigated using transmission electron microscopy (TEM). This systematic analysis provides insight into the effects of deposition temperature on the morphological and structural properties of low-temperature ALD-grown HZO thin films, offering a fundamental understanding for process optimization in high-k dielectric applications.

Indium-based oxide semiconductors (OS) such as In₂O₃¹⁾, IGZO²⁾, IGO³⁾, IWO⁴⁾, and ITO⁵⁾ have garnered significant attention for future logic and memory applications due to low leakage, high mobility, and BEOL compatibility as channel materials. As the OS film is expected to be grown on a 3D architecture different from a Si crystal, there is a strong demand for ALD indium precursors which enable conformal deposition, precise thickness and compositional control. As a result, we have focused on indium precursor development for high temperature ALD processing to produce high quality InOx-based thin films with a very small amount of organic impurities.

Here we present DKI-6 which is a heteroleptic indium precursor with bulky β-diketimine and methyl ligands (Fig.1). It is a liquid at room temperature, has a 1 torr vapor pressure at 105^oC, and decomposed at 328^oC (onset, DSC). DKI-6 successfully produced smooth and high quality In₂O₃ films with a GPC of 0.54 Å/cycle on an SiO₂ substrate using O₃ ALD processing at 300^oC (Fig.2 and Fig.3). Interestingly, we found Si diffusion into the In₂O₃ film from the SiO₂ underlayer using H₂O ALD at 300℃, which could imply lower density In₂O₃ film growth with lower GPC of 0.40Å/cycle (Fig.4).

In conclusion, we successfully obtained ALD In₂O₃ films using DKI-6 and O₃ or H₂O coreactants at 300^oC with the reasonable GPC. This result will extend into further development of various kinds of InOx-based OS thin films.

Reference: 1. Peide Ye, IEDM2025, T3, 2. Mutsumi Okajima, et al., IEDM2025, 29-1, 3. Kyooho Jung, et al., IEDM2025, 29-3, 4. Hyeonwoo Park, et al., VLSI2025, T1-3, 5. Md Sazzadur Rahman, et al., IEDM2025, 22-6

Tantalum(V) oxide (Ta₂O₅) is a critical material for advanced optical coatings and next-generation DRAM capacitors due to its high refractive index, low optical absorption, and high dielectric constant [1]. Atomic Layer Deposition (ALD) is the preferred method for depositing highly uniform and conformal films required for these applications, especially on curved substrates. However, common tantalum precursors (e.g. TBTDET, TBTEMT) often lead to films with high carbon and nitrogen contamination [2,3], which is detrimental to thin film performance. This work introduces a novel tantalum precursor, RosiTa^TM, for the ALD of high-quality Ta₂O₅ thin films.

A novel liquid Ta precursor, RosiTa^TM was synthesized and characterized. Its thermal properties and volatility were evaluated by thermogravimetric analysis (TGA). RosiTa^TM has good volatility (1 Torr at 106 ^oC, Fig. 1), and presents long-term thermal stability with no decomposition detected after 12 weeks at 110°C, making it suitable for ALD applications. Ta₂O₅ thin films were deposited by thermal ALD on silicon substrates using RosiTaTM as tantalum source and ozone (O₃) as the oxygen source. The deposition was carried out in a temperature range of 200-350 °C, with a GPC ~0.48 Å/cycle (ALD window 275-300 oC). The resulting films were analyzed by X-ray photoelectron spectroscopy (XPS) (Fig. 2) to determine their composition and purity. The ALD process using RosiTa^TM and O₃ yielded highly conformal Ta₂O₅ thin films with excellent step coverage on high-aspect-ratio structures (Fig. 3).

A key finding of this work is the exceptionally low nitrogen and carbon contamination in the Ta₂O₅ films grown with RosiTa^TM. This is a significant improvement over other precursors (e.g. TBTDET, TBTEMT) and is a critical advantage for different applications.

The novel volatile tantalum precursor, RosiTa^TM has been successfully used for the ALD of high-quality Ta₂O₅ thin films. RosiTa^TM stands out due to its excellent thermal stability and the ability to produce highly conformal Ta₂O₅ films with nitrogen and carbon contamination below the detection limit for XPS. These features make RosiTa^TM a very promising precursor for demanding ALD thin film applications.

REFERENCES

[1] C. Chaneliere et al, Materials Science and Engineering: R. 22, 269 (1998).

[2] T. Blanquaart et al, Semicond. Sci. Technol. 27, 074003 (2012).

High-bandwidth memory (HBM) is essential for AI-based computing, necessitating the development of high-performance dynamic random access memory (DRAM). DRAM devices are evolving toward higher efficiency through higher integration, which inevitably requires reducing the physical size of DRAM capacitors. Therefore, the development of next-generation high-k dielectric materials that maintain sufficient capacitance without compromising leakage current levels is crucial. In this study, we investigated bismuth oxide (Bi₂O₃) films deposited by atomic layer deposition (ALD) as a promising high-k candidate material for future DRAM capacitors. We explored the applicability of bismuth tertiary-butoxide (Bi(O^tBu)₃), a precursor with limited research experience in ALD processes. Furthermore, we compared the structural and electrical properties of films deposited using different reactants (O₂ and O₃). The comparative analysis revealed significant differences in growth behavior, crystallinity, and interface quality depending on the choice of reactants. Additionally, the energy bandgap and dielectric constant were evaluated to determine the material's suitability for scaled capacitor nodes. This presentation explores the potential of ALD-grown Bi₂O₃ as a viable dielectric solution for next-generation DRAM technology.

Cobalt oxide thin films are of significant interest for applications in electrochemical energy storage, catalysis, gas sensing, and emerging electronic and neuromorphic devices, where precise control over phase, stoichiometry, and surface morphology is critical. In this work, we report a comprehensive study of the growth behavior and property evolution of cobalt oxide thin films deposited by atomic layer deposition (ALD) using cobalt(II) ethylpropanimidamidato as the metal precursor and ozone or water vapor as the oxidant, with particular emphasis on the role of deposition temperature. Saturated ALD growth was achieved within a temperature window of 180–260 °C. Film composition and oxidation states were analyzed using X-ray photoelectron spectroscopy (XPS), while crystallographic structure was examined by X-ray diffraction (XRD). Atomic force microscopy (AFM) revealed a strong dependence of surface morphology on deposition temperature. Raman spectroscopy confirmed that films deposited at lower temperatures exhibit a mixed-phase composition consisting of Co₃O₄ and CoO, whereas higher temperatures promote phase purity. Spectroscopic ellipsometry was employed to determine film thickness and extract temperature-dependent optical constants. This work demonstrates ALD as a highly repeatable and scalable pathway for depositing uniform cobalt oxide thin films with tunable phase composition and optical properties, enabling materials optimization for application-specific integration.

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¹D. Mandia, L. Brogan, M. Griffiths, and J. O’Loughlin, “Selective and Superconformal Molybdenum Growth Strategies for Advanced Metallization,” IEEE IITC, 2025, pp. 1–3, doi: 10.1109/IITC66087.2025.11075465 [https://doi.org/10.1109/IITC66087.2025.11075465]

As device dimensions continue to shrink, TiN as the electrode material for advanced devices faces critical limitations, including high resistivity and increased leakage current density arising from its relatively low work function (~4.2 eV) [1,2]. These constraints drive the need for improved electrode materials for the next scaled technological node. Vanadium nitride (VN) is a promising candidate owing to its favorable characteristics, including a high work function (up to ~5.5 eV), low resistivity, and notable mechanical properties [3].

In this work, we focus on the development of a BEOL-compatible, low-temperature thermal ALD process for vanadium nitride (VN) thin films, employing BRUTE^® anhydrous hydrazine (N₂H₄) as the nitrogen source to enable integration as a potential electrode material for next-generation devices. Using the anhydrous N₂H₄ source, uniform VN thin films were successfully deposited at temperatures as low as 250 °C, achieving a growth rate of ~0.05 nm per cycle and a film density of ~5.40 g/cm³. XPS analysis of a 10 nm VN film deposited at 250 °C confirmed successful nitride formation at this reduced temperature, although ~15 at. % oxygen contamination was detected within the film. The as-deposited VN films exhibited a resistivity as low as ~600 μΩ·cm, with less than 5% variation across the test wafer, indicating good film uniformity and electrical consistency. MOS capacitors will be fabricated to further evaluate the electrical properties of the deposited films. Detailed experimental procedures and comprehensive characterization results will be discussed.

References

[1] S. E. Kim et al., Adv. Mater. Technol. 8,2200878 (2023)

[2] W. Kang et al., ACS Appl. Mater. Interfaces 16, 57446 (2024)

[3] A. Jan, ALD/ALE 2025, AF-MoP-35

Atomic layer deposition (ALD) is widely used due to its precise deposition capabilities, allowing for the creation of very thin, conformal, and high-quality films on the nanometer scale. These films are ideal for applications requiring precise barrier layers, passivation layers, or protective coatings in complex geometries, particularly in microelectronics, sensors, and medical devices. ALD deposition of alumina offers several advantages, including uniform coating on complex 3D structures, precise thickness control, high purity, and suitability for sensitive substrates due to its low deposition temperature. The self-limiting behavior of ALD cycles allows for controllable film growth in which a homogenous film can be achieved at the lowest film thickness. To control the thickness in a range of few nanometers, it is important to understand the interaction between the reactants and substrate during the nucleation period, or the first few cycles. X-ray photoelectron spectroscopy (XPS) is a well-established technique for non-destructive analysis of the chemical composition of thin layers and interfaces. By analyzing a material at varying takeoff angles between the sample and analyzer, angle dependent XPS (ADXPS) can be utilized to probe the thickness and chemical composition of thin films without creating ion beam-induced damage associated with destructive sputter profiling. The spectral results obtained by ADXPS can be furthered evaluated by StrataPHI, a software product designed by Physical Electronics, to calculate not only the thickness of thin films but also provide an estimate of fractional coverage, which is of great importance for high-throughput metrology of thin-film structures. This presentation will highlight the benefits of utilizing angle dependent XPS in combination with StrataPHI modeling software to non-destructively characterize and simultaneously calculate the layer thickness and fractional coverage of a series of aluminum oxide films deposited on glass substrates throughout the nucleation period by the ALD process.

Pnictogen hydrides, such as PH3, have been used to dope silicon (Si) surfaces during the fabrication of quantum electronic devices with atomic-scale precision. Additionally, dissociative adsorption of XH3 is believed to effectively alter surface energetics and morphology during film growth, enabling control over dopant concentration and spatial distribution within the film. Once the dopant is incorporated into the surface, the growth of silicon can be affected by the dopant’s concentration as well as its chemical and physical properties. Developing a fundamental understanding of dopant characteristics and growth processes is essential to ensure and improve a priori prediction of suppressed or enhanced growth rates and uniformity in critical Si film deposition for many applications, including logic, NAND, and DRAM devices.

In this study, we first performed ab initio molecular dynamics (AIMD) simulations of SiH4 (a Si precursor) deposition on the Si(001) surface at various dopant concentrations. Our simulations show that dilute dopant concentrations at the surface, in the absence of hydrogen, do not significantly affect SiH4 deposition. To have a meaningful impact on Si film growth, an adequate amount of dopants must be present on the surface. We also analyzed the detailed reaction mechanism of SiH4 deposition on a surface using a dimer model at the density functional theory level with dissociatively adsorbed XH3. For the XH3-incorporated Si(001) surface, we considered the most widely used dissociative adsorption states: XH2+H, XH+2H, and X+3H. Our results indicate that the energy barrier for silane (SiH4) deposition increases in the presence of XH3 compared to a surface without dopants, implying slower film growth. The magnitude of the energy barrier—and its effectiveness in limiting film growth—strongly depends on the state of adsorbed XH3 (XH+2SiH versus X+3SiH) on the Si surface. Furthermore, we will discuss how surface-site dependence influences Si adsorption relative to dopant location and chemistry (e.g., As, Sb, P), aiming to link these effects to intrinsic dopant properties, such as electronegativity and atomic radius.

As DRAM capacitor structures continue to scale down, achieving ultrathin dielectric films with high capacitance density and low leakage current has become increasingly important. Rutile-phase TiO₂ is a promising high-k dielectric material due to its intrinsically high dielectric constant; however, stabilizing the rutile phase in ultrathin films remains challenging because of phase instability and interfacial degradation.

In this study, RuO₂ bottom electrodes were fabricated by reactive RF sputtering using a metallic Ru target, with oxygen flow ratios of 20%, 30%, and 40% and substrate temperatures ranging from 300 to 500 °C. These parameters significantly influenced the oxidation state and crystallinity of the RuO₂ films, which in turn affected the subsequent growth behavior of TiO₂. TiO₂ thin films were deposited on the RuO₂ electrodes using remote plasma plasma-enhanced atomic layer deposition (PEALD), and the impact of RuO₂ seed layer crystallinity on TiO₂ phase evolution was systematically investigated. Post-deposition oxygen annealing was additionally employed to enhance rutile phase stability.

As a result, highly crystalline rutile-phase TiO₂ thin films were successfully obtained, exhibiting an equivalent oxide thickness below 1 nm and leakage current densities lower than 10⁻⁵ A cm⁻².

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant No. RS-2025 25396489) and this work was supported by K-CHIPS(Korea Collaborative & High-tech Initiative for Prospective Semiconductor Research) (2410011219, RS-2023-00237030, 23027-15FC) funded by the Ministry of Trade, Industry & Energy(MOTIE, Korea).

High-quality SiO₂ films were deposited by plasma-enhanced atomic layer deposition (PEALD) using hexamethyldisilylaminodimethylaminosilane (HMDMS, (Me₃Si)₂N-SiH₂-NMe₂) and O₂ plasma at 550°C, achieving growth per cycle (GPC) of 2.5 Å/cycle. For comparison, thermal ALD process using the same precursor with O₃ at 700°C reported GPC of 3.0 Å/cycle, excellent electrical properties and good conformity [1]. Secondary ion mass spectrometry (SIMS) analysis revealed that PEALD SiO₂ films exhibit comparable C and N impurity levels to a thermally grown oxide film, with only 30% higher H content. The wet etch rate in 100:1 diluted HF was 1.5 Å/s, approximately twice that of thermal oxide (0.8 Å/s), indicating excellent film density. Transmission electron microscopy demonstrated outstanding conformality, with 98.6% step coverage for 10-nm-thick films on 20:1 aspect ratio hole patterns. Electrical characterization of 20-nm-thick PEALD SiO₂ films showed low leakage current density (0.7 nA/cm² at -2 MV/cm) and Fowler-Nordheim tunneling behavior at high electric fields, confirming high-purity, defect-free dielectric properties comparable to thermal SiO₂ ALD at 600-700°C [1]. The combination of high GPC, excellent conformality, and superior electrical properties makes this PEALD process promising for dielectric gap-fill applications in advanced semiconductor devices, particularly 3D NAND memory.

[1] C. Kim et al. “High-temperature high-growth-rate atomic layer deposition of SiO₂ using hexamethyldisilylamino-dimethylamino-silane,” Appl. Surf. Sci. 723 (2026) 165606. https://doi.org/10.1016/j.apsusc.2025.165606

Atomic layer deposition (ALD) of ZnO is a key enabling technology in advanced electronic and optoelectronic devices, but the benchmark precursor diethylzinc (DEZ) shows limited thermal stability in the higher temperature regimes required for next–generation processes. In this work, we evaluate a new zinc precursor, AP–MDS™ 131, with the dual objectives of improving high–temperature process robustness relative to DEZ (>150 °C for H₂O and >250 °C for O₃) and achieving lower, more controllable growth rates within well–defined ALD windows. Thermogravimetric and calorimetric data indicate that AP–MDS™ 131 combines usable volatility with enhanced thermal stability, supporting operation at elevated temperatures without precursor decomposition under ALD conditions; moreover, AP–MDS™ 131 is non–pyrophoric, in contrast to pyrophoric DEZ, which has clear handling and safety advantages.

Process studies show that both DEZ and AP–MDS™ 131 exhibit no detectable decomposition on SiO₂ under the tested high–temperature conditions, but they differ in desorption behavior and process windows. For O₃–based ZnO ALD, literature and internal data indicate that DEZ lacks a clear high–temperature ALD window due to strong desorption, whereas AP–MDS™ 131 provides a distinct high–temperature ALD window with only limited desorption at even higher temperatures. At representative conditions, both precursors display saturation behavior consistent with self–limiting ALD growth.

With H₂O as co–reactant, AP–MDS™ 131 enables an additional ALD window at intermediate temperatures, with well–defined saturation of both precursor and reactant and no evidence of decomposition on SiO₂. In comparison, DEZ/H₂O operates at lower temperatures and yields higher growth per cycle, whereas AP–MDS™ 131/H₂O provides substantially reduced growth rates within its window—a central development target to enable highly controlled, thickness–tunable processes. Across all investigated conditions, ZnO films from both precursors exhibit carbon below detection, near–stoichiometric O/Zn ratios, and high densities, demonstrating that the improved high–temperature capability and reduced growth rate of AP–MDS™ 131 are achieved without compromising film quality.

Overall, AP–MDS™ 131 expands the usable ALD window for ZnO toward higher temperatures for both O₃ and H₂O processes compared to DEZ, while offering lower, more manageable growth rates, non–pyrophoric handling, and maintaining high film purity and near–ideal stoichiometry—making it a strong candidate for tightly controlled ZnO ALD in microelectronics and display technologies.

Multicomponent metal-oxide thin-film transistors (TFTs) are promising candidates for next-generation memory components owing to their high electron mobility and low-leakage properties. For example, Indium-Gallium-Zinc-Oxide (IGZO) films are candidates for channel materials in 3D DRAM. Given the aggressive features of proposed device architectures, ALD of IGZO type films will be required for vertical scaling. The incumbent precursor for many indium-containing films is InMe₃, a pyrophoric solid which presents physical challenges and limitations to widespread adoption and underscores the need for novel, safe, and suitable precursor chemistry to accommodate ALD growth.

We report, herein, on physical properties and thermal analysis of a structurally diverse collection of indium compounds, including known and novel compositions. We also present varied synthetic approaches to organometallic indium compounds with an emphasis on non-pyrophoric routes and reagents. In addition, we discuss In₂O₃ film growth from a newly developed non-pyrophoric organometallic indium precursor.

Imaging spectroscopic ellipsometry (ISE) combines spectroscopic sensitivity with spatially resolved measurements, providing a powerful, non-destructive approach for characterization of ultra-thin materials. In this work, ISE is applied to wafer-scale MoS₂ and WS₂ films deposited by atomic layer deposition, enabling simultaneous mapping of thickness and optical properties with micrometer-scale spatial resolution. This capability is well suited for deposition process development and uniformity assessment.

Precise thickness control in multilayer stacks motivates the development of aluminum oxide (Al₂O₃) atomic layer deposition (ALD) processes with intrinsically low growth-per-cycle (GPC). We evaluated new organoaluminum precursors—AP-MDS™ 026 and AP-MDS™ 027—against conventional chemistries (e.g., TMA, TDMAA, aluminum sec-butoxide, Al(mmp)₃) to identify process windows that reliably deliver low GPC while maintaining surface saturation, film uniformity and high conformality.

Across co-reactants, both H₂O- and O₃-based processes exhibited clear precursor saturation behavior, with O₃ generally yielding lower deposition rates than H₂O under otherwise comparable process conditions.

Benchmark GPCs spanned approximately 1.0–1.2 Å/cycle for TMA/O₃ and 0.8–1.0 Å/cycle for TDMAA/H₂O or O₃, decreasing to 0.4–0.5 Å/cycle for aluminum sec-butoxide/O₃ (<250 °C) while water processes always yield growth rates above 0.6 Å/cycle. Notably, AP-MDS™ 027 paired with O₃ enabled the lowest GPC regime observed, ~0.19–0.26 Å/cycle at 250–300 °C, while AP-MDS™ 026/H₂O and AP-MDS™ 027/H₂O both yielded ~0.6 Å/cycle under the measured conditions rendering them as suitable candidates for lowering the growth rate of aluminum oxide ALD with both ozone and water as co-reactants.

Early-cycle behavior (i.e. growth delay) was strongly precursor- and co-reactant-dependent and substrate effects on growth were more pronounced for AP-MDS™ 026 and AP-MDS™ 027 compared to conventional precursors. Moreover, process optimization emphasized the benefits of a less reactive, sterically bulkier yet volatile and thermally stable precursor for controllable Al₂O₃ ALD.

Collectively, these results establish O₃-driven and H₂O-driven AP-MDS™ 026 and AP-MDS™ 027 as a robust route to sub-0.3 Å/cycle and ~0.6 Å/cycle Al₂O₃ ALD, respectively. Our processes demonstrate that precursor selection, co-reactant and substrate choice provide orthogonal controls to tune nucleation and growth for angstrom-level thickness control in complex multilayer architectures.

As semiconductor devices shrink below 2-nm, copper (Cu) interconnect reliability is increasingly constrained by electromigration and diffusion into surrounding dielectrics. Traditional capping layers such as Cobalt provide protection but add unwanted parasitic resistance and limit further scaling. Graphene offers a promising alternative due to its atomic thickness and high electrical conductivity [1-2]. However, integration of graphene in the back-end-of-line stack requires protection of graphene structure and properties from the downstream processing steps such as thin film deposition, etching, etc. This work investigates the impact of plasma assisted (DL1) and thermally grown (DL2) dielectric thin films on the graphene composition, thickness, and hybridization states using VeraFlex (XPS) and Elipson (Raman) metrology tools, developed by Nova Ltd. The study identifies key process–structure correlations and strategies to enable reliable graphene–dielectric integration in advanced interconnects.

Sensitivity of many graphene attributes, like layer-number identification, structural quality and defects, makes Raman spectroscopy a promising tool for process development [3-4]. Plasma deposition, which uses ions bombardment of the surface, can lead to significant damage to the substrate layers [5]. Here, we examine the extent of this effect in multiple scenarios. The Raman spectra reveals that the thermal DL2 layer deposited directly over Graphene had minimal impact on the Graphene’s spectrum, while a plasma DL1 layer changed significantly. The significant change in graphene quality by DL1 is evident from the drop of the 2D peak intensity, indicating reduction in the quality of the graphene film as compared to pristine graphene and graphene_DL2 sample (Fig.1). On patterned wafers, the graphene quality deteriorates when exposed to the plasma deposition even when protected by one or few thermal layers. This damage is reflected in the reduction of the 2D peak amplitude and peak broadening. However, as the number of thermal layers increases, the extent of this damage diminishes (Fig.2), indicating DL2 can offer partial protection against plasma-induced damage. Complementary XPS analysis confirmed uniform deposition of both DL1 and DL2. Compared to the sp²/sp³ ratio derived from the C1s spectra of pristine graphene (Fig.3a), DL1 processing leads to a reduction in the sp²/sp³ ratio, indicating increased disorder, whereas optimized DL2 layers restore a higher sp² fraction, consistent with reduced damage (Fig.3b). Further, the results demonstrate uniform thermal DL2 growth and a clear correlation between DL2 thickness and graphene protection (Fig.4). These findings provide process-level insight into dielectric–graphene interactions and establish guidelines for integrating graphene with dielectric thin films in advanced interconnects.

Hafnium oxide (HfO_x) is a versatile material with applications across multiple technological fields. Its compatibility with CMOS processes enables integration into microelectronic devices, where its high dielectric constant makes it an attractive alternative to silicon dioxide. In addition, hafnia exhibits a high refractive index, which is advantageous for optical and protective coating applications, while its excellent thermal stability supports use in high-temperature environments.

Atomic layer deposition (ALD) provides precise control over the growth of HfOₓ thin films, with process parameters strongly influencing the deposition rate and resulting film properties. In this work, we investigate the effects of deposition temperature, precursor pulse time, and purge time on the properties of thermal ALD-grown HfOₓ films. A full-factorial design of experiments is employed to systematically evaluate how these parameters affect growth per cycle, refractive index, and film density.

We use tetrakis(dimethylamido)hafnium (TDMAH) as the metal precursor, and H₂O as the oxygen source. We measure the film refractive index using spectroscopic ellipsometry and the film density using X-ray reflectivity. The analysis enables identification of the statistically relevant factors and how factor interactions influence each response, providing optimal ALD process conditions to tune HfOx deposition.