The semiconductor industry has continued to achieve high economic growth due to device price reductions as a result of die shrink and larger diameter wafers. Although the progress of die shrink has been slowing down somewhat, research and development are tackling various fields for further growth and development.In this symposium, we plan lectures given by prominent researchers in the field of fine processing and measurement technology to support the future development of semiconductors and their related industries. We expect lively discussions on future research trends in semiconductor manufacturing and on the directions to aim for.

Recent semiconductor volume manufacturing is supported by DUV (KrF/ArF) light source. and next generation will be supported by EUV lightsource. I will discuss about DUV progress and its appriction to nano direct processing. We have demonstrated actual collector mirror reflectivity degradation rate is less than 0.4%/Gp by using real collector mirror around 125W (at I/F clean) in burst power during 30 Billion pulses operation. Recently we have redefined target power higher >330W and its development plan.

While the miniaturization of semiconductor devices is now approaching the atomic-scale limit, the demand for higher performance of computer chips is ever growing, which has driven new device technologies such as three dimensional structures and new materials. This trend also demands further innovation in process technologies, especially plasma process technologies. In this work, the latest process technologies and numerical simulation technologies that facilitate a better understanding of the underlying physical/chemical mechanisms of the new processes will be reviewed and discussed.

The structure of semiconductor devices has changed to nanometer-scale three-dimensional ones in order to meet the requirement of low power consumption and high capacity. Atomic layer processing, which offers excellent ability to control uniformity, conformality, and thickness, will be important for next generation of semiconductor manufacturing. In this talk, recent progress in atomic layer etching is reviewed after briefly introducing the technology trends in the fabrication of semiconductor devices. The topics included are fundamental of atomic layer etching, typical procedures of atomic layer etching, and atomic layer etching of various materials.

The advance semiconductor fabrication, in which circuits are fabricated in nanometer scale, is constantly engaged in battles against nanometer-sized contamination / defects. The further evolution of the processes are supported and facilitated by understanding of its underlying mechanisms, a thorough improvement of reaction uniformity, and ultraclean technology. Focusing on semiconductor wet cleaning and CMP (Chemical Mechanical Polishing), which is fighting with nano-contamination / defects, the mechanism and advanced technology are reviewed in perspective of surface science.

Planar-type electron sources based on graphene-oxide-semiconductor (GOS) structure are MOS type electron sources which can be driven by applying 10-20 V with high emission current density of 1-100 mA/cm². We have proposed neutralizers using the GOS type electron sources for a micro ion engine. For such an ion engine, the emission current of 1 mA or more is required for neutralizing the ion beam. Hence, we have fabricated the GOS type electron sources with hundreds of small emission area, and successfully achieved the emission current of over 1 mA.

An electrospray ion source using ionic liquid has been applied to microthrusters since it is easily miniaturized and suitable for space applications. However, the thrust density of the electrospray thrusters is lower than that of other microthrusters. Hence, it is necessary to increase the density of ion emitters. We have fabricated a high-density array of capillary-needle-type emitter electrodes employing a fabrication process of field emitter arrays. The number density of emitters is about 10,000 times higher than that of the conventional emitter arrays.

We aim at forming atomically thin hydrogen-terminated Si layers by a novel self-assembly method in solutions. In this report, we deposited Ag atoms at the edges of a flattened Si(111) surface. And the surface was chemically etched assisted by the Ag nanowires. Then we confirmed that perforated nano-grooves were formed along the atomic edges of Si(111), of which the width and the depth were approximately 10 nm and 2 nm, respectively. These results enabled us to obtain techniques to separate Si layers with different thicknesses.

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We have developed a nanoscale local surface potential measurement technique referred to as open-loop electric potential microscopy (OL-EPM) based on atomic force microscopy (AFM). In this study, we directly visualize time-dependent changes of the local distribution of the corrosion cells under the liquid-environment mimicking the solution condition for the chemical mechanical polishing (CPM) process.

The down-scaling of integrated circuits is approaching economical and technological limits, and thus diversification is expected as another growth direction, so called “More than Moore”. For the diversification of microelectronics, integration with other kinds of components, i.e. heterogeneous integration, is one of promising approaches. This paper reports wafer-level heterogeneous integration and packaging technologies based on a wafer-to-wafer bonding process which enable the combination of dissimilar materials and components into single systems and hermetic packaging at a same time.

Recently infrared/UV laser has faced resolution limit of finer micromachining requirement on especially semiconductor packaging like Fan-Out Wafer/Panel Level Package and Through Glass/Fused silica Via hole for 5G tele communication and high-performance PC. In this study, we have investigated ablation rate with deep ultraviolet excimer laser to explore its possibilities of micromachining on organic and glass/fused silica interposers.We have succeeded 3um holes on organic film aspect ratio >2 and 10 um hole aspect ratio >50 on glass/fused silica interposer without any significant defects. DUV Excimer lasers could be expected on manufacturing process for next generation semiconductor packages.

We have developed a new chemical route to form a graphene/SiC structure. Our process is plasma oxidation of SiC at temperatures lower than 150°C followed by HF etching to remove surface oxides (SiO₂). The subsequent anneal of the treated SiC surface with an additional carbon layer in ultrahigh vacuum forms graphene with a low pit density on SiC. We report our recent progress on characterizing the formed graphene by Raman spectroscopy, AFM and electrical measurements.

In this study, the initial oxidation processes of ultrathin hafnium films on clean Si(111)-7×7 surface [Hf/Si(111)] were investigated by Hf 4f, Si 2p, and O 1s core-level photoelectron spectroscopy. As our results, Hf/Si(111) with a thickness of 2 ML including Hf monosilicide (HfSi) on surface shows low reactivity with O₂ molecules, while one of 6 ML including HfSi at interface and metallic Hf component on surface shows high reactivity with them.

Nitrogen-vacancy centers (NV) in diamond is an emerging highly-sensitive nanoscale magnetometer. In addition, the NV center can detect ac magnetic field. In this study, we have demonstrated that the Gigahertz range of ac magnetic field produced by the spin wave is detectable via the NV center. Surface spin waves excited in a ferromagnetic insulator; yttrium iron garnet was detected by optically detected magnetic resonance and its Rabi oscillation signal of the NV center.

In this talk, I will summarize the presentations in the symposium of "Forefront of semiconductor manufacturing ∼micro-processing and inspection of ultimately minimized devices∼"

We will put more focus on the effect of competitive surface-site occupation between carbon and other surface-active impurities on single-layer graphene (SLG) growth. It is known that sulfur is a typical impurity of metals and the most surface-active element. The surface sites are finally occupied by sulfur at the elevated temperatures by surface segregation. In the case of Ni(110) surface, it is confirmed by scanning Auger microscopy, LEEM and STM that the available surface sites are nearly occupied by sulfur with a centered 2x2 arrangement. When the Ni(110) is doped with carbon, surface segregation of carbon shall be strongly affected by such a surface-active element. In this situation, we discovered a strongly directional growth of SLG, exhibiting a square-like shape. The detailed characterization at the nanoscale and interesting growth mechanism shall be discussed.

The friction force of a monolayer MoS₂ on graphite was measured by sliding MoS₂ islands with an atomic force microscope. Examining the change of the friction force depending on the area of MoS₂ under the same conditions, it was found that the larger the contact area of MoS₂, the larger the friction force was.

Graphene is anticipated to exhibit excellent high-frequnecy carrier transport properties because of its excellent electronic properties. However, the measured device performances are deteoritated from theoretical values. We study on high-performance radio-frequency graphene devices using Y natural oxide that enables to form a good interface between graphene gate dielectrics. In this presentation, we will show the superiority of Y natural oxide, based on evaluation of high frequency carrier transport properties.

Monolayer MoS₂ is a promising material for gas sensing due to its large surface-volume ratio. However, its slow response / recovery in room temperature prevents practical sensor applications. Recently, we found that the gas response of the monolayer MoS₂ is activated under light illumination. In this study, we show that the response and recovery rates linearly increase with light intensity. This result can be explained by Langmuir adsorption model in consideration of photo-stimulated gas desorption.

The growth of single-walled carbon nanotubes was attempted by hot-filament assisted CVD using Pt catalysts. The growth experiment was carried out in a mixture of methanol vapor and Ar gas that contains 3 % H₂. Single-walled carbon nanotubes were obtained after the growth at 580℃ for 30 min. RBM peaks in the Raman spectra were observed at 160 cm^-1, 224 cm^-1, 264 cm^-1 and 280 cm^-1.

Graphene nanoribbon (GNR) has attracted much attentions as a new novel conductive nanowire. GNR can be fabricated by unzipping carbon nanotubes (CNT). However, the unzipping process is not clear. In this study, we challenge to understand the unzipping mechanism using home-built ultra-high vacuum (UHV) scanning tunneling microscopy (STM). CNT/GNR solution was sprayed in vacuum on an atomically-flat clean Cu(111) surface. We will report how the CNT deform or unzip with an application of voltage, current, heat, electric field and force.

We synthesized graphene by magnetron-plasma-enhanced chemical vapor deposition and analyzed its growth stages by using in-situ ellipsometry. It was observed that the growth form and nuclei density of graphene differ depending on substrate materials. Experiments of the control of first stages of graphene growth on silicon dioxide through in-situ ellipsometry monitoring of the surface is being carried out to grow highly crystalline graphene.

It is important to understand the surface of micro- or nano-domains that we can see abundantly in nanotechnology. We have developed a technique to analyze the surface structure of such small domains, combining the scanning electron microscope and the Weissenberg Reflection High-Energy Electron Diffraction. In order to demonstrate the method, we prepared the two types of grating-like structures on Si(110) substrates by photolithography and etching. As the result of observation of diffraction patterns, we have found the changes of structures. There are two equivalent rectangular unit cells on Si(110), however, one of the two orientations was dominantly observed near the edge of the top surfaces and bottoms. Also, it is found there are micro-slopes at the edges of grating-like structures.

Various structure models for Cu/Si surface superstructure have been proposed. The exact structure, however, has not yet been determined. In this study, we have performed structure analysis of Cu/Si(111) using total-reflection high-energy positron diffraction (TRHEPD) combined with data-driven science. As a result it has been revealed that the surface forms a Cu₂Si superstructure with buckling. In the presentation, we describe the details of experiment, analysis, and the determined atomic arrangement.

Recently, iron oxides and hydroxides have attracted attention as catalyst due to their low cost and environmental safety. Emerging electrosynthetic techniques provide simple and inexpensive approaches to the synthesis of iron oxide-based materials. In this work, the iron oxide films were prepared by electrodeposition and characterized by in situ X-ray absorption spectroscopy to track changes in iron oxidation state and local structure of the films during electrochemical reaction of the film caused by applying external voltage for further understanding the formation of iron oxide-based materials.

CNTs/PDMS as a promising nanocomposite for tomato harvesting application has been investigated. The I-V and I-t characteristics as well as tomato hardness measurement and support-vector machine learning was utilized to determine the performance of the sensor in terms of nanocomposite. The data suggested an accurate and stable measurement in a low weight region of tomato. The I-V hysteresis reduced substantially towards higher weight region as a result of increase in electrons pathways. The fabricated sensor displayed higher sensitivity than the commercial sensor. In addition, machine learning of resistance-displacement curve data suggested 0.67 accuracy when tested with acquired data.

Vibrational motions of surface adsorbates are fundamental degrees of freedom that govern various surface dynamics including catalytic processes and thermal conduction. It is vital to understand their excitation and relaxation dynamics in time domain. We have been working on time-domain observation of vibrational dynamics of surface adsorbates by using optical nonlinear spectroscopy with ultrashort laser pulses. In this talk, our recent research on vibrational dynamics of carbon monoxide and alkali atoms on metal surfaces will be demonstrated.

Spatial regulations of the flow of surface plasmon waves are realized by using waveguiding structures or band-engineering concepts based on plasmonic crystals. Frequency filtering of surface plasmon waves are achieved by forming nano-scale cavities on metal films. Based on time-resolved imaging techniques and numerical simulations of electromagnetic fields, this paper will discuss the control of surface plasmon waves by using artificial nano-structures.

Low-energy electron microscopy (LEEM) has superior spatial and temporal resolutions, and is suitable for investigations of surface dynamical changes. In this talk, we review our research to understand processes governing surface mass transport through in-situ LEEM observations and diffusion equation analysis of step motions during thermal relaxation, crystal growth, and phase transition.

In the present talk, we show our recent results on ferromagnetic topological heterostructures formed by subsurface incorporation of magnetic layers into topological insulator films. These systems have the advantage compared to those previously studied (magnetic impurity doped topological insulators or topological insulators/ferromagnets heterostructures with large structural difference) in that (i) the magnetic layer is ordered, and (ii) the interaction between the topological insulator and magnetic atoms is large.

In two-dimensional transition metal dichalcogenides, valley and spin degrees of freedom couple with each other reflecting the inversion symmetry breaking of the lattice and strong spin-orbit interaction. In such a system, it is expected that we can control the spin degree of freedom through valley manipulation and vice-versa. In this presentation, I will report the recent our progress on the study of characteristic valley-spin properties in two dimensional van der Waals nanostructures. I will also discuss the microscopic mechanism and perspectives.

Recently, it has been revealed that superconductivity can occur even in one-atomic-layer metal films. In an ultrathin film grown on a substrate, the asymmetry of the confining potential is expected to cause the Rashba spin-orbit interaction. Experimental results obtained by us suggest that Rashba superconducting phases are realized in monolayer Pb films and multiple monolayer systems. Furthermore, we have observed magnetic-field-induced superconductivity in Pb films containing magnetic impurities with a low Kondo temperature.

In recent years, transition metal dichalcogenides (TMDC) family such as MoS₂ and WSe₂ has attracted much attention due to their remarkable optoelectronic properties. For the first time in the world, we succeed to combine multiprobe techniques with femto-second pulsed laser system. By using the multiprobe optical method, we measured WSe₂/MoSe₂ in-plane heterostructure on SiO₂/Si substrate. As a result, we evaluated the band structure including the schottkey barrier of probe-sample interface and band shift on MoSe₂/WSe₂ interface and positional dependence of carrier dynamics. This technique is expected to play an important role in the researches to develop advanced twodimentional devices with microscopic structures.

Yttrium oxyhydride (YO_xH_y) exhibits unique photochromic properties in electrical resistivity and optical transparency, attracting photoelectronic applications such as smart windows and optical sensors. To enhance the photo-induced physical-property variation, in this study, we attempted 1): epitaxial growth of YO_xH_y thin films, and 2): irradiation of ultraviolet laser. Consequently, we achieved reversible change in resistivity by 7 orders of magnitude, in clear contrast to that previously reported in polycrystalline thin films using sunlight (one order of magnitude). Furthermore, we found that temperature dependence of resistivity was metallic after the irradiation of UV laser to the YO_xH_y thin film.

NaTaO₃ (NTO) has drawn attention as a material showing a high photocatalytic activity in water splitting. Previous studies have shown that each Sr-doped NTO (Sr-NTO) particle has a Sr concentration gradient inside the particle, and some of Sr atoms substitute for Ta atoms at the B-site. However, there are still remained many unexplained facts about the structure-photocatalytic properties relationship. In this talk, we will discuss the effects of the structures of compositionally-grade Sr-NTO thin films fabricated by pulsed laser deposition (PLD) on their photocatalytic activity.

Hybrid facing sputtering is characterized in that the plasma state and sputtering voltage can be easily set and controlled to the optimum state for the material without breaking the vacuum, and the substrate impact effect of high energy particles can be suppressed. The effect of lowering the sputtering voltage Vdc was investigated when using an RF-DC coupled power supply in the preparation of ITO transparent conductive film using hybrid facing sputtering.

A thin film deposition technology at room temperature is required for a device manufacturing process on a flexible substrate with low heat resistance used in the field of flexible electronics such as organic EL display. Applying the room temperature CVD and ALD deposition method using mixed gas of high purity ozone and ethylene (C₂H₄) reported previously, We report the film quality of Al₂O₃ thin films prepared using trimethylaluminum (TMA) as a precursor.

We examined an analysis method of the interface between metal film and organic film on glass and Si substrates. TOF-SIMS equipped with GCIB(Gas Cluster Ion Beam) is very useful to evaluate for organic material. However, it is difficult to analyze the interface from metal film side, because the sputter rate of GCIB for metals is very slow. We report the method to analyze the interface by combining back side polishing and TOF-SIMS measurement from the organic film.

Various surface treatments are applied for corrosion protection of the equipment materials. The mechanism and the feature of each treatment are introduced with application examples.

Total reflection X-ray fluorescence analysis is used for elemental analysis in a thin film. Similar to this idea, we are developing a total reflection neutron ray gamma ray analysis method (Total-reflection Neutron activated Gamma spectroscopy, TN-γ method). Along with the measurement of neutron reflectivity, gamma rays generated in the nuclear reaction of neutrons are analyzed by a semiconductor detector. It enables analysis of light elements that are difficult with fluorescent X-rays.

In addition to the normal thermal expansion, another significant contribution on the thickness change of poly(N-isopropylacrylamide) (PNIPAM) ultrathin film has been found under the ambient conditions. With monitoring by multichannel X-ray reflectometry, it is found that the thickness change of PNIPAM ultrathin film can be affected by the moisture in its hydrophilic and hydrophobic state. Furthermore, an asymmetric thickness change has been found in the temperature cycle. Under the ambient conditions, the thickness of PNIPAM ultrathin film can keep stable during the cooling when the temperature is above the lower critical solution temperature (LCST). But as cooling exceed the LCST, the thickness can increase immediately with swelling. If the heating run was conducted after the cooling, the thickness can decrease monotonically, even though the temperature scan is across the LCST.

The growth rate of hydrogenated amorphous Si (a-Si:H) films is enhanced at high temperature due to the thermal desorption of surface-covering hydrogen. However, the activation energy is often extremely low (<1 eV) as for hydrogen desorption, which is found to be originated from a catalytic effect of proton that is coming onto the growing surface. A possible reaction mechanism to account for such a low activation energy is presented by using molecular orbital calculations.

Biomolecules working as nanoscale complex systems play essential roles in a wide variety of biofunctions. Frequency modulation atomic force microscopy (FM-AFM) is a powerful method capable of directly analyzing such molecular-scale biosystems. Here, the recent results of hydration structures and charge density distribution around biomolecules obtained by FM-AFM are presented. In addition, interaction forces between biomolecules has been directly investigated by two/three dimensional force mapping method.

Visualizing dynamic behavior of biological processes occurring on plasma membranes of living cells with nanometer scale resolution is recognized to be quite difficult because of extremely fragile structures of plasma membranes as well as living cells itself. To visualize them, In this study, we developed high-speed ion conductance microscopy (HS-SICM). We will show HS-SICM movies that capture dynamic morphological changes of nanostructures on plasma membranes of living cells. In addition, we will show method to map of surface elastic responses of living cells with nanometer scale resolution by HS-SICM.

Interaction between extracellular materials, such as anti-cancer drug molecules and intracellular components are complex and many aspects remain unclear. In this contribution, we will introduce a noble method to realize remote excitation of surface enhanced Raman scattering using noble nanowire as plasmonic waveguide and detection of Raman signals inside a single live cell with high sensitivity. As an example, we will discuss dynamics of anti-cancer drug molecule - DNA interaction detected with the remote excitation of surface enhanced Raman scattering.

Molecular fingerprints act as natural contrasts to biomolecules. Vibrational spectroscopic imaging using molecular fingerprints, i.e., molecular fingerprinting, is opening new opportunities to reveal cellular machinery and enable molecule-based diagnosis. In this talk, I will introduce biomedical spectroscopic imaging using the coherent anti-Stokes Raman scattering (CARS) process.

Atomic force microscopy (AFM) has been widely used to characterize local mechanical properties of single cells, allowing us to map not only the apparent Young’s modulus, but also rheological properties of cells at the subcellular resolution. Furthermore, AFM has a potential to explore the mechanical properties of multi-cellular system such as embryo and ex vivo tissue at the single cell level. I will present how the mechanical properties of single- and multi-cells can be quantified by AFM and discuss the recent trends and potential directions in cell mechanics.

In this study, we introduce an AI-robot system utilizing Bayesian optimization to expand the search space for solid-state inorganic compounds. This system fully automates sample transfer, thin film deposition, and growth condition optimization-all addressing the physical aspects of fabrication. The figure shows the design of our apparatus, which is equipped with a central robot arm that can access each satellite chamber for automatic thin-film growth and physical-property measurements. Using the values obtained from the physical-property measurements, the Bayesian optimization algorithm predicts the next growth condition to obtain better values. An example of Bayesian optimization is shown for the epitaxial growth of TiH₂ thin films with two parameters. Through the automated thin-film synthesis and optimization, we aim to establish new materials research style to drastically accelerate solid-state inorganic materials research.

Materials explorations using materials informatics mainly consists of a combination of computational chemistry and machine learning. In order to be added to the vast data extracted from research papers and to accumulate big data under unified experimental conditions, we have to develop high-throughput preparation, evaluation and analysis system. In this presentation, I would like to show the exploration of multi-element materials exploration in bulk system which is heterogeneous reaction.