Large Scale Integration Process Research Articles

Single-Electron Transistor Operation of a Physically Defined Silicon Quantum Dot Device Fabricated by Electron Beam Lithography Employing a Negative-Tone Resist

We have proposed and demonstrated a device fabrication process of physically defined quantum dots utilizing electron beam lithography employing a negative-tone resist toward high-density integration of silicon quantum bits (qubits). The electrical characterization at 3.8 K exhibited so-called Coulomb diamonds, which indicates successful device operation as single-electron transistors. The proposed device fabrication process will be useful due to its high compatibility with the large-scale integration process.

Room Temperature Light Emission from Superatom-like Ge-Core/Si-Shell Quantum Dots.

We have demonstrated the high-density formation of super-atom-like Si quantum dots with Ge-core on ultrathin SiO2 with control of high-selective chemical-vapor deposition and applied them to an active layer of light-emitting diodes (LEDs). Through luminescence measurements, we have reported characteristics carrier confinement and recombination properties in the Ge-core, reflecting the type II energy band discontinuity between the Si-clad and Ge-core. Additionally, under forward bias conditions over a threshold bias for LEDs, electroluminescence becomes observable at room temperature in the near-infrared region and is attributed to radiative recombination between quantized states in the Ge-core with a deep potential well for holes caused by electron/hole simultaneous injection from the gate and substrate, respectively. The results will lead to the development of Si-based light-emitting devices that are highly compatible with Si-ultra-large-scale integration processing, which has been believed to have extreme difficulty in realizing silicon photonics.

A Comprehensive Survey on Electronic Design Automation and Graph Neural Networks: Theory and Applications

Driven by Moore’s law, the chip design complexity is steadily increasing. Electronic Design Automation (EDA) has been able to cope with the challenging very large-scale integration process, assuring scalability, reliability, and proper time-to-market. However, EDA approaches are time and resource demanding, and they often do not guarantee optimal solutions. To alleviate these, Machine Learning (ML) has been incorporated into many stages of the design flow, such as in placement and routing. Many solutions employ Euclidean data and ML techniques without considering that many EDA objects are represented naturally as graphs. The trending Graph Neural Networks (GNNs) are an opportunity to solve EDA problems directly using graph structures for circuits, intermediate Register Transfer Levels, and netlists. In this article, we present a comprehensive review of the existing works linking the EDA flow for chip design and GNNs. We map those works to a design pipeline by defining graphs, tasks, and model types. Furthermore, we analyze their practical implications and outcomes. We conclude by summarizing challenges faced when applying GNNs within the EDA design flow.

ПРЕДПОСЫЛКИ И ПЕРСПЕКТИВЫ СОСТЫКОВКИ ЕАЭС И «ПОЯС И ПУТЬ»

Modern Eurasia is the most important center of political influence in the world. The integratial processes that are forming on the continent around Russia and China have historical prerequisites, expressed in the desire to strengthen their own influence and increase their importance in the region. The purpose of the article is to determine the prerequisites and prospects for the coexistence of the concepts of the EAEU and the "Belt and Road" as examples of large-scale integration processes in Eurasia. For a deeper understanding of the possibility of coexistence of the two initiatives, the work raises the question of the interpretation of the problem by both domestic and Chinese researchers. The author paid special attention to the historical aspect of the development of the integration idea on the example of the two countries, which was necessary for a more complete understanding of the motivation of the Russian Federation and the PRC in the field of promoting their own vision of the Eurasian system. The relevance of the topic is due to the possible collision of interests of Russia and China with respect to the spheres of foreign policy interests, in connection with which, based on historical experience, the study of the problem allows us to give the most probable forecast for the further development of events. As a result of the research, the author comes to the conclusion that the possibility of coexistence of the Chinese and Russian concepts lies in mutual concessions on key issues and deepening cooperation. The practical significance of this work lies in the fact that the author first considered the sources, namely the publications of Chinese authors on the coexistence of two concepts of Eurasian integration, which can expand the knowledge of domestic researchers regarding the Chinese vision of the problem raised in the study.

Optomechanical mass spectrometry

Nanomechanical mass spectrometry has proven to be well suited for the analysis of high mass species such as viruses. Still, the use of one-dimensional devices such as vibrating beams forces a trade-off between analysis time and mass resolution. Complex readout schemes are also required to simultaneously monitor multiple resonance modes, which degrades resolution. These issues restrict nanomechanical MS to specific species. We demonstrate here single-particle mass spectrometry with nano-optomechanical resonators fabricated with a Very Large Scale Integration process. The unique motion sensitivity of optomechanics allows designs that are impervious to particle position, stiffness or shape, opening the way to the analysis of large aspect ratio biological objects of great significance such as viruses with a tail or fibrils. Compared to top-down beam resonators with electrical read-out and state-of-the-art mass resolution, we show a three-fold improvement in capture area with no resolution degradation, despite the use of a single resonance mode.

ЦЕННОСТНАЯ И СОЦИАЛЬНО-ПСИХОЛОГИЧЕСКАЯ ТУРБУЛЕНТНОСТЬ КАК ФАКТОР ОБНОВЛЕНИЯ РОССИЙСКОГО МЕНТАЛИТЕТА

The article deals with the manifestations of value and social-psychological turbulence as a factor of the update of the Russian society’s mental structures. The idea that large-scale integration processes and internal restructuring of the entire living space have influenced the metaphysical foundations of the Russian spirit and emphasised their binarity and ambivalence is substantiated. Dispersion of meaning-value and social-psychological attitudes has generated postmodernistic forms of behaviour and interaction, which are a response to the mutual influence of archaic and transnational identities.

Interlayer Dielectric Bonding for 300mm Wafers

Nowadays, the large-scale integration process using 300 mm Si wafers is the main stream in the manufacturing process for commercial devices. Furthermore, wafer-level hybrid bonding technology is the key issue for the 3D high-density integration devices. For hybrid interface with metal and interlayer dielectric, both materials are required for the reliable connection. In particular, the interlayer dielectric layers have various materials and conditions in order to apply for each device such as SiO2 by thermal oxide, tetraethyl orthosilicate, or silane; SiN, quartz, and so on. The direct bonding technology has been investigated for several decades, and several bonding methods are applicable for the wafer-level bonding. In particular, surface activated bonding (SAB) method with Ar fast atom bombardment (Ar-FAB) or plasma activated bonding (PAB) are the essential technology for wafer-level hybrid bonding. In this research, several interlayer dielectric substrates were prepared on 300 mm Si wafers; SiO2 by thermal oxide, tetraethyl orthosilicate, or silane; SiCN, and the several process parameters including pre-process for the bonding has been investigated and evaluated their bonding quality. In this abstract paper, partial results are described: Thermal oxide SiO2 (100 nm thickness) wafers were bonded by PAB process. Bonded wafers were evaluated by C-mode scanning acoustic microscopy (C-SAM) for voids confirmation and blade strength measurement. (Fig.1) Also, the bonded interface has been observed by the cross-sectional transmission electron microscopy (TEM) observation. (Fig.2) At the interface of among the bonded wafers, there is only one void due to a particle intervening interface during bonding process. The peripheral unbonded area seems to correspond to the touched area by the transferring process. Furthermore, the cross-sectional TEM image shows the stable bonded interface without voids. In the conference program, we would like to present the each optimized bonding process for each ILD material cyclopaedically. Figure 1

The HEURECA method: Tracking multiple phase coupling dynamics on a single trial basis

BackgroundAlthough acquisition techniques have improved tremendously, the neuroscientific understanding of complex cognitive phenomena is still incomplete. One of the reasons for this shortcoming may be the lack of sophisticated signal processing methods. Complex cognitive phenomena usually involve various mental subprocesses whose temporal occurrence varies from trial to trial. Mostly, these mental subprocesses require large-scale integration processes between multiple brain areas that are most likely mediated by complex, non-linear phase coupling mechanisms. Consequently, a spatiotemporal analysis of complex, multivariate phase synchronization patterns on a single trial basis is necessary. New methodThis paper introduces the HEURECA method (How to Evaluate and Uncover Recurring EEG Coupling Arrangements) that enables the dynamic detection of distinguishable multivariate functional connectivity states in the electroencephalogram. HEURECA adaptively divides a trial into segments of quasi-stable phase coupling topographies and assigns similar topographies to the same synchrostate cluster. ResultsHEURECA is evaluated by means of simulated data. The results show that it reliably reconstructs a time series of recurring phase coupling topographies and successfully gathers them into clusters of interpretable neural synchrostates. The advantages and unique features of HEURECA are further illustrated by investigating the popular complex cognitive phenomenon insight. Comparison with existing methodsUnlike existing methods, HEURECA detects complex phase relationships between more than two signals and is applicable to single trials. ConclusionsSince HEURECA is applicable to all kinds of circular data, it not only provides new insights into insight, but also into a variety of other phenomena in neuroscience, physics or other scientific fields.

A theoretical model incorporating both the nano-scale material removal and wafer global uniformity during planarization process

In the ultra large-scale integration process, as chemical mechanical polishing (CMP) is developing to higher precision, nano level planarity and sub-nano level roughness of wafer surfaces become key problems to be overcome. In this work, a theoretical model for local and total material removal was proposed based on the particle sliding trajectories and chemical-mechanical synergy, and the material removal distribution on wafer surface were analyzed. Furthermore, the chemical-mechanical mechanism was studied and synergy maps constructed. It is found that the passivation-wear and additive-synergistic effects dominate the material removal during CMP. This study establishes a correlation mechanism between the nano material removal and global uniformity of wafer surfaces, which provides theoretical and experimental framework for optimizing the slurry and the process parameters.

Review Article: Progress in fabrication of transition metal dichalcogenides heterostructure systems.

Transition metal dichalcogenide (TMDC) semiconductors have attracted significant attention because of their rich electronic/photonic properties and importance for fundamental research and novel device applications. These materials provide a unique opportunity to build up high quality and atomically sharp heterostructures because of the nature of weak van der Waals interlayer interactions. The variable electronic properties of TMDCs (e.g., band gap and their alignment) provide a platform for the design of novel electronic and optoelectronic devices. The integration of TMDC heterostructures into the semiconductor industry is presently hindered by limited options in reliable production methods. Many exciting properties and device architectures which have been studied to date are, in large, based on the exfoliation methods of bulk TMDC crystals. These methods are generally more difficult to consider for large scale integration processes, and hence, continued developments of different fabrication strategies are essential for further advancements in this area. In this review, the authors highlight the recent progress in the fabrication of TMDC heterostructures. The authors will review several methods most commonly used to date for controllable heterostructure formation. One of the focuses will be on TMDC heterostructures fabricated by thermal chemical vapor deposition methods which allow for the control over the resulting materials, individual layers and heterostructures. Another focus would be on the techniques for selective growth of TMDCs. The authors will discuss conventional and unconventional fabrication methods and their advantages and drawbacks and will provide some guidance for future improvements. Mask-assisted and mask-free methods will be presented, which include traditional lithographic techniques (photo- or e-beam lithography) and some unconventional methods such as the focus ion beam and the recently developed direct-write patterning approach, which are shown to be promising for the fabrication of quality TMDC heterostructures.

High resolution TEM analysis of focused ion beam amorphized regions in single crystal silicon—A complementary materials analysis of the teardrop method

The predominant challenge of nanomachining by focused ion beam (FIB) is the generational down-scaling of minimum dimensions of cutting-edge technologies such as very large scale integration (VLSI) process technology. To keep pace with feature size reduction, the state of the art FIB beam profiles must also shrink proportionally. This requirement for FIB profile shrinking necessitates tests that analyze FIB profiles and their characteristics. With such tests in hand, the suitability for VLSI technology applications may be specified, developed, and qualified. The authors present herein various aspects and some fine details of the recently improved beam profile analysis, aka “teardrop” test. This test is based on obtaining real beam characteristics by analyzing amorphization traces produced by scanning the beam in question over a [001] Si single crystal sample, in a series of lines of increasing doses, followed by thorough analysis procedure. To derive the most accurate beam characteristics, the amorphized r...

Deposition and XPS studies of dual sputtered BCN thin films

Thin films of boron carbon nitride (BCN) are deposited by co-sputtering of B4C (Direct Current—DC) and BN (Radio frequency—RF) targets with varying N2/Ar gas flow ratio and DC target power. BCN being a low-k material and a potential inter layer dielectric (ILD), the deposition and surface analysis become prime factors for ultra large scale integration (ULSI) process and device integration. In this study, a thorough analysis on deposition rate of BCN thin films is conducted as a function of various N2/Ar gas flow ratios, target powers and substrate deposition temperatures. XPS studies are conducted to ascertain the chemical composition and bonding of the deposited BCN films for the various deposition parameters. The deposition rate is found to show a decreasing trend with an increase in substrate deposition temperature but showed an increasing trend at 400°C. As the sputtering yield of B4C target is far greater than that of BN target, the deposition rate and XPS studies are conducted for the target powers of 20W and 40W for the B4C target. The deposition rate showed a decreasing trend from N2/Ar=0.25 to 0.75, but increases at N2/Ar=1. The XPS characterization indicates the formation of BCN phase distinctly with few separate phases of CN and BN.

Synthesis and gas-sensing properties of the silicon nanowires/vanadium oxide nanorods composite

As air pollution is becoming more and more serious in recent years, gas-sensing devices have attracted intensive attention. In particular, NO2 is one of the most toxic gases in the atmosphere, which tends to produce acid rain and photochemical smog. Thus, there is a strong demand of cheap, reliable and sensitive gas sensors targeting NO2. Gas sensors fabricated on silicon substrates with room-temperature operation are very promising in power saving, integrated circuit processing and portable detectors. More important, the silicon nanowires (SiNWs)-based devices are compatible with very large scale integration processes and complementary metal oxide semiconductor technologies. In the present work, the novel nanocomposite structure of (SiNWs)/vanadium oxide (V2O5) nanorods for NO2 detection is successfully synthesized. The SiNWs are fabricated by a combination of nanosphere lithography and metal-assisted chemical etching. Vanadium films are deposited on SiNWs by DC magnetron sputtering, and then V2O5 nanorods are synthesized with subsequent thermal annealing process for full oxidation in air. The morphology and crystal structure of product obtained are characterized by field-emission scanning electron microscopy and X-ray diffraction. The characterization results indicate that V2O5 nanorods are uniformly distributed on the surfaces of SiNWs. The increased specific surface area of SiNWs/V2O5 nanocomposite provides more adsorption sites and diffusion conduits for gas molecules. Therefore, the novel structure of the nanocomposite is conducive to gas-sensing. In addition, the sputtering time has an obvious influence on the morphology of vanadium oxide. With the increase of the sputtering time, the specific surface area and the number of p-n heterojunctions formed in the nanocomposite are both less than those of nanocomposite with appropriate sputtering time. The gas-sensing properties are examined by measuring the resistance change towards 0.5-4 ppm NO2 gas at room temperature by the static volumetric method. Results show that the nanocomposite with shorter deposition time has better gas-sensing properties to low-concentration NO2 gas than those of bare SiNWs and nanocomposite with longer deposition time. On the contrary, the responses of the nanocomposite to other high-concentration reducing gases are very low, indicating good selectivity. The enhancement in gas sensing properties may be attributed to the change in width of the space charge region, which is similar to the behavior of p-n junction under forward bias, in the high-density p-n heterojunction structure formed between SiNWs and V2O5 nanorods. In conclusion, these results demonstrate that the SiNWs/V2O5 nanocomposite has great potential for future NO2 gas detection applications with low consumption and good performance.

Introduction of Atomically Flattening of Si Surface to Large-Scale Integration Process Employing Shallow Trench Isolation

Atomically flattening technology was introduced to the widely used complementary metal oxide silicon process employing sallow trench isolation at the 0.22-μm technology node. Two methods were investigated. The first method is to apply the atomically flattening to the starting Si wafer, and the second method is to apply this just before forming the gate oxide. In both methods, atomically flat gate insulator/Si interface could be obtained, and the test array circuit for evaluating the electrical characteristics of many (>130,000) metal oxide semiconductor field effect transistors was successfully fabricated on an entire 200-mm-diameter wafer. By evaluating the test circuit, the noise amplitude of the gate–source voltage related to the random telegraph noise was reduced owing to introducing the atomically flat gate insulator/Si interface. The charge-to-breakdown of the gate oxide was also improved.

Achievement of a near-perfect smooth silicon surface

During the ultra large scale integration (ULSI) process, the surface roughness of the polished silicon wafer plays an important role in the quality and rate of production of devices. In this work, the effects of oxidizer, surfactant, polyurethane pad and slurry additives on the surface roughness and topography of chemical-mechanical planarization (CMP) for silicon have been investigated. A standard atomic force microscopy (AFM) test method for the atomic scale smooth surface was proposed and used to measure the polished silicon surfaces. Finally, compared with the theoretical calculated Ra value of 0.0276 nm, a near-perfect silicon surface with the surface roughness at an atomic scale (0.5 A) was achieved based on an optimized CMP process.

Patterned 3D assembly of Au nanoparticle on silicon substrate by colloid lithography

We patterned self-assembly monolayer of protecting organic shell for ca. 3–4-nm gold nanoparticles directly onto a Si substrate by using very large-scale integration process involving electron beam lithography and oxygen plasma treatment. AuNPs assembled from colloid solution to construct a patterned bottom layer of dense lines and square dots including resolution from 200 nm to 10 μm through the patterned protecting organic shell on a large area. The nanowire and nanodots of 3D AuNP assemblies were fabricated by cross-linking AuNPs layer-by-layer through dithiol groups as a linker, so-called bottom-up construction. The interparticle distances among the AuNPs decreased with constructed layers of 3D AuNP assemblies, causing the significant change in electrical resistivities of nanowires. Semiconducting property of the nanowires of AuNP assembly for 1–10 constructed layers was obtained by the resistivities under applying various voltages. In addition, the cross-linking of 3D AuNP assemblies merged as insolated AuNP clusters after thermal treatment at 140 °C demonstrated significant change in morphology and resistivity. The key feature of this approach is the manipulation of AuNPs as nanowires with temperature-dependent effect and semiconducting property, which could function as a nanosensor to minimize the device.

Fabrication of a Highly Dense Line Patterned Polystyrene Brush on Silicon Surfaces Using Very Large Scale Integration Processing

In this study we used a novel fabrication process, involving a very large scale integration and isotropic oxygen plasma treatment to generate highly dense lines and well-defined patterns of polystyrene (PS) brushes on patterned Si(100) surfaces. We defined trench patterns having a duty ratio of 1:1 on the Si surface using electron beam lithography and then applied isotropic oxygen plasma (IOPT) to treat the bottom of the trenches. The resolution of the line patterns of the PS brushes approached 160 nm, with a duty ratio of 1:1. We established the surface grafting polymerization kinetics of the PS chains on the Si surface by analyzing their thicknesses and number-average molecular weights (Mn). The propagation rate (kp) and active grafting species deactivation rate (kd) had values of 3.3 × 10−2 s−1 M−1 and 7.5 × 10−5 s−1, respectively. The measured thicknesses (ellipsometry) and analyzed values of Mn (gel permeation chromatography) of the corresponding “free” PS fit well to the polymerization kinetics model. In addition, we used friction coefficients to verify the structures of the dense lines of patterned PS brushes after immersion in various solvents. We observed different patterns and friction coefficients for the surfaces presenting dense lines of PS brushes grafted from 160 nm wide trenches for 26 h, after immersion in water and toluene, respectively. Thus, the densely patterned PS brushes on the Si surface exhibited solvent-responsive switching properties.

Patterned Poly(2-hydroxyethyl methacrylate) Brushes on Silicon Surfaces Behave as “Tentacles” To Capture Ferritin from Aqueous Solution

We have used a very large scale integration process to generate well-defined patterns of polymerized 2-hydroxyethyl methacrylate (HEMA) on patterned Si(100) surfaces. An atom transfer radical polymerization initiator covalently bonded to the patterned surface was employed for the graft polymerization of HEMA to prepare the poly(2-hydroxyethyl methacrylate) (PHEMA) brushes. After immersing wafers presenting lines of these polymers in water and cyclohexane, we observed brush- and mushroom-like regions, respectively, for the PHEMA brushes, with various pattern resolutions. The PHEMA brushes behaved as "tentacles" that captured ferritin complexes from aqueous solution through entanglement between the brushes and the ferritin proteins, whose ferritins were trapped due to the collapsing of the PHEMA. Using high-resolution scanning electron microscopy, we observed patterned ferritin iron cores on the Si surface after thermal removal of the patterned PHEMA brushes and ferritin protein sheaths.

Are we moving towards an integrated European Research Area?

This empirical paper addresses the question whether the European science base has become more coherent and more integrated during the years immediately prior to the EU27 expansion in 2004. Comparative quantitative indicators describe and analyze broad patterns and macro-level trends within intra-EU scientific cooperation, at various high aggregate “macro” levels, drawing on bibliometric analysis of jointly authored research articles published in the years 2001–2005. This study provides country-level co-publication statistics describing the geographical distribution of each member state’s research partners - domestically, within the EU27 and outside the EU27. The results show signs that cooperation within the EU as a whole has increased noticeably during recent years. Some of the new EU27 member states show a relatively strong preference for EU research partnerships, but no conclusive macro-level evidence was found of structural transformations and large scale integration processes toward a highly interconnected ‘European Research Area’.

Electrical Properties of Carbon Nanotubes Grown at a Low Temperature for Use as Interconnects

We measured the electrical properties of vertically aligned carbon nanotubes (CNTs) synthesized from via holes by radical chemical vapor deposition at a low temperature of 390 °C, which meets the requirements of the Si large scale integration (LSI) process. To use the CNTs could be used for LSI wiring, we applied chemical mechanical polishing (CMP) to the CNTs and successfully reduced the via resistance by a factor of ten. In addition, the resistance of the CNTs was reduced further to 0.6 Ω for 2-µm-diameter vias by annealing at 400 °C. Although the temperature dependence of the resistance of the CNTs grown in vias (CNT-vias) did not indicate ballistic transport, which is one of the expected properties of CNTs, we found that CMP and annealing are effective for reducing the via resistance of CNTs.