Interconnect Formation Research Articles

Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration

Abstract An overview of various low-temperature (<200°C) wafer bonding processes using metal interlayers is presented. Such processes are very attractive for novel applications in 3D heterogenous packaging as the allow for simultaneous formation of electrical interconnects, as well as hermetic encapsulation of various sensors and microelectromechanical systems-based devices. Metal wafer bonding is a generic category of processes consisting of various sub-categories, each one defined by the different principles governing the process. One can differentiate between eutectic wafer bonding (a eutectic alloy is formed as bonding layer during the process by liquid-solid interdiffusion), intermetallic wafer bonding (an intermetallic alloy is formed as bonding layer during the process by solid-liquid interdiffusion, a process known also as solid liquid intermetallic diffusion transient liquid phase, and metal thermo-compression wafer bonding. Different critical/gating parameters were investigated and their impact for generally reducing processing temperatures for the different metal bonding systems was studied.

Study of selective etching of TaN with respect to SiOCH dielectrics using SiF4 plasma processes

TaN is used as a Cu diffusion barrier during metal interconnect formation to enable modern chip fabrication. In this study, the selective removal of TaN with respect to SiOCH dielectrics is explored using neutral dominant plasmas containing pure SiF4 or with O2 or H2 additives. SiF4 is studied because the Si-containing gas has been historically used to deposit Si-based films, but the gas also contains F capable of volatilizing Ta. This work explores the possibility of enabling both selective etching of TaN and selective deposition on SiOCH. SiF4 discharges are impacted by the addition of O2 and H2 gases; exhibiting significantly different deposition and etching regimes. The substrate temperature plays a critical role in modulating the TaN etching versus deposition window compared to SiOCH. Through this work, selective etching of TaN with respect to SiOCH is achieved.

Moore's Law Scaling and Chemical Mechanical Planarization (CMP)

Since the invention of the first integrated circuit in 1958, chemistry and materials have played a critical role in semiconductor process technologies, which has led to an exponential growth of transistors packed into circuits. Decades ago, Gordon Moore posited there would be a doubling of components every two years (revised from his original doubling every one-year prediction). This observation became known as Moore’s law.As Denard scaling took on more complexity, the number of new materials used to build semiconductors increased at a torrid pace. The number of elements in the periodic table, used to fabricate devices, increased roughly five-fold from the 1980’s to the 2000’s.In the earlier years, lithography, etch, thin films, implant, and diffusion were foundational technologies used to fabricate a silicon wafer into hundreds of microchips. In the late 1980’s a new technology Chemical Mechanical Planarization (CMP) was invented. It was developed out of necessity to reduce topography, critical for lithography’s depth of focus requirements. Without this key invention, patterning and building layer upon layer from front end transistors to back-end interconnects would not have been possible.Intel implemented CMP into manufacturing in the early 1990’s on the 0.8 micron technology node which manufactured the 486 microprocessor. CMP was required to planarize dielectric oxide used to insulate the aluminum metal interconnects. Since then, the number of CMP applications over the last three decades has exploded, enabling the scaling of Moore’s Law.CMP is not only used to improve lithography depth of focus. CMP also enables a method of metal interconnect and contact formation called damascene. Planarization is used to create dielectric isolation trenches, discrete plugs for insulation, aid advanced patterning architectures, build through silicon vias (TSVs), and enable complex wafer and chip bonding for die-to-die interconnects for disaggregated products.Transistor scaling alone is no longer sufficient to meet device performance, power, and cost requirements. Complex material and architectural changes are required. And novel CMP applications continue to be added at each new technology node. This author will make an argument that CMP is critical to push scaling and enable future process nodes. Figure 1

Mechanism of Interconnected Pore Formation in High Internal Phase Emulsion-Templated Polymer.

High internal phase emulsion-templated polymer, named polyHIPE, has received widespread attention due to its great potential applications in many fields, such as separation, adsorption, heterogeneous catalysis, and sound absorption. The broad applicability is largely dependent on its adjustable opening structure. However, the question of why polyHIPE has an interconnected pore network structure is still to be discussed. Herein, different types (w/o, o/w, and o/o) of HIPEs are prepared and subsequently detected with laser scanning confocal microscopy (LSCM), and the polyHIPEs obtained by curing the HIPEs are characterized by SEM. The observations suggest that the interconnected pore formation is primarily due to the presence of the surfactant-rich phase in the film between the neighboring droplets in HIPE. The interconnected pores are generated by removal of the surfactant-rich domains in the postcuring procedure, and their sizes would be enlarged if the solubility of the surfactant in the continuous phase decreases in the curing stage.

Interstate power interconnection along with carbon dioxide emission constraint collaboration: Effective tool for low-carbon electric power expansion in Northeast Asia

Interstate electric power integration with the formation of interstate electric ties and power interconnection in Northeast Asia has been studied for several years. Research has examined the directions, indicators, costs, and systemic (integration) benefits (technical, economic, environmental, etc.) of forming such ties and grids. Studies conducted in different Northeast Asia countries have shown that despite the significant investments required to create an interstate electric ties infrastructure, which serves as the basis for interstate power grids and electricity markets development, participants of these interstate power grids and markets gain substantial benefits. These include reduced needs for installed and reserve generation capacity, lower electricity prices, increased overall flexibility of power resources, and accordingly, greater capability to integrate renewable energy sources. This results in reduced carbon dioxide (CO2) emissions from fossil fuel power plants. The latter undoubtedly contributes to achieving the sustainable development goals set by the United Nations and reducing anthropogenic climate impact, which many countries globally (including Northeast Asia) have targeted via announced carbon neutrality by 2050–2060. The main target of the article is to conduct and present new multi-scenario study on forming a potential Northeast Asia’s interstate power grid under national and grid-wide (for the entire power system interconnection) carbon emission constraints. The mathematical model of electric power system expansion and dispatching was modified to account for carbon dioxide emission constraints and used for the study. The results of the study showed that the creation of interstate power grid in Northeast Asia accompanied by climate change collaboration among countries to control carbon dioxide emission would lead to effectively constraining of carbon dioxide emission in the subregion, which is the novelty of the study. The results of the study are useful and applicable for choosing particular ways, options, stages of formation and expansion of low-carbon power system interconnection in Northeast Asia.

Low gelatin concentration assisted cellulose nanocrystals stabilized high internal phase emulsion: The key role of interaction

Low concentrations of gelatin (0.02–0.20 wt%) were applied to regulate the surface and interface properties of CNC (0.50 wt%) by forming CNC/G complexes. As gelatin concentration increased from 0 to 0.20 wt%, the potential value of CNC/G gradually changed from −44.50 to −17.93 mV. Additionally, various gelatin concentrations led to micromorphology changes of CNC/G complexes, with the formation of particle interconnection at gelatin concentration of 0.10 wt%, followed by network structure and enhanced aggregation at gelatin concentration of 0.15 and 0.20 wt% respectively. The water contact angle (25.91°-80.23°) and interface adsorption capacity of CNC/G were improved due to hydrophobic group exposure of gelatin. When gelatin concentration exceeded 0.10 % at a fixed oil phase volume fraction (75 %), a high internal phase emulsion (HIPE) stabilized by CNC/G can be formed with a good storage stability. The rheological and microstructure results of HIPE confirmed that low gelatin concentration can assist CNC to form stable emulsion structure. Especially, the auxiliary stabilization mechanism of various gelatin concentration was different. CNC/G-0.10 % and CNC/G-0.15 % stabilized HIPE mainly depended on the enhanced interface adsorption and network structure, while CNC/G-0.20 % stabilized HIPE mainly relied on enhanced interface adsorption/accumulation due to weak electrostatic repulsion and aggregate granular morphology of CNC/G-0.20 %.

Physiological cell bioprinting density in human bone-derived cell-laden scaffolds enhances matrix mineralization rate and stiffness under dynamic loading.

Human organotypic bone models are an emerging technology that replicate bone physiology and mechanobiology for comprehensive in vitro experimentation over prolonged periods of time. Recently, we introduced a mineralized bone model based on 3D bioprinted cell-laden alginate-gelatin-graphene oxide hydrogels cultured under dynamic loading using commercially available human mesenchymal stem cells. In the present study, we created cell-laden scaffolds from primary human osteoblasts isolated from surgical waste material and investigated the effects of a previously reported optimal cell printing density (5 × 106 cells/mL bioink) vs. a higher physiological cell density (10 × 106 cells/mL bioink). We studied mineral formation, scaffold stiffness, and cell morphology over a 10-week period to determine culture conditions for primary human bone cells in this microenvironment. For analysis, the human bone-derived cell-laden scaffolds underwent multiscale assessment at specific timepoints. High cell viability was observed in both groups after bioprinting (>90%) and after 2 weeks of daily mechanical loading (>85%). Bioprinting at a higher cell density resulted in faster mineral formation rates, higher mineral densities and remarkably a 10-fold increase in stiffness compared to a modest 2-fold increase in the lower printing density group. In addition, physiological cell bioprinting densities positively impacted cell spreading and formation of dendritic interconnections. We conclude that our methodology of processing patient-specific human bone cells, subsequent biofabrication and dynamic culturing reliably affords mineralized cell-laden scaffolds. In the future, in vitro systems based on patient-derived cells could be applied to study the individual phenotype of bone disorders such as osteogenesis imperfecta and aid clinical decision making.

Process and Design Challenges for Hybrid Bonding

Hybrid bonding is one of the key technology to enable solutions for high bandwidth with increasing power and signal integrity. Hybrid bonding involves, face-to-face interconnect formation between wafers and it acts as an extension of fusion bonding technology. Wherein, dielectric materials such as silicon dioxide bond at room temperature and the copper vias embedded in the dielectric expand to form the electrical connections, enabling the interconnect formation between the top and bottom wafer.Hybrid bonding provides advantages over traditional C4 flip-chip bonding involving solder-based micro-bumps, such as, interconnect pitch scaling to less than 10 µm thereby providing higher interconnect density and increased power and signal speed efficiency for memory and high-performance computing application along with better reliability. It is compatible with standard CMOS fabrication technology.In this work, we would like to present the design and process challenges which may lead to improved bonding yield. To enable hybrid bonding with high yield it is necessary that the bonding surfaces are flat with low roughness. The optimized chemical mechanical polishing (CMP) process is one of the key process technology which enables surface topography to be less than 10 nm and surface roughness to be less than 0.8 nm. The surface topography is dependent on the metal via layout, interconnect density and the surrounding dielectrics and hence, these design parameters act as a guiding principle for the application-oriented definition of the design to accommodate different pitch sizes of interconnecting vias (from 1 µm to 10 µm). The mechanical properties of the materials play a key role as well as this will define the removal rate of dielectric and the metals during the CMP process which will affect the dishing and the surface topography. To achieve high bonding yield the surface topography is key as this will affect the bond front propagation and hence the bonded and non-bonded region between the dielectrics. To further improve the bonding yield we have applied a tailored annealing recipe which improves the bonding yield significantly. This paper would focus our work on topography improvement and overall bonding yield in detail and a comparison of bonding yield with and without dummy vias. Dummy vias in this context refer to the copper via structures that are not intended for interconnect formation but are there for CMP process optimization to achieve better process control. Hence, the dummy vias are not connected to the underlying routing metal layer.Figure 1, shows an ideal surface that would result in W2W bonding with high yield. Figure 2 shows, the defects such as high copper dishing, copper protrusion, dielectric erosion and poor surface topography which will result in poor bonding yield. Figure 3 shows the bonding using SiON as the bonding dielectric with (a) without dummy copper vias (~98% bond yield) and (b) with dummy copper vias (~88% bond yield). Figure 1

Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration

The low temperature metal bonding processes (<200°C) are attractive methods for novel applications in 3D packaging with simultaneous formation of electrical interconnections and hermetic encapsulation for microelectromechanical systems.Metal wafer bonding is a generic category of processes consisting of various sub-categories, each one defined by the different principles governing the process. One can differentiate between eutectic wafer bonding (a eutectic bonding layer is formed during process by liquid-solid interdiffusion), intermetallic bonding (an intermetallic alloy is formed as bonding layer during the process by solid-liquid interdiffusion, process known also as Solid Liquid Intermetallic Diffusion – SLID or Transient Liquid Phase – TLP), and metal thermo-compression (TC) wafer bonding.The bonding temperature range for the two types of processes showing liquid interface is relatively narrow (<10-20°C) while for metal TC the bonding temperature range is quite broad (~200°). This important parameter is differentiating the focus in studying the processes: for the low temperature eutectic and SLID/TLP the focus is primarily on the development of new materials systems and secondary on process optimization, while for metal TC the focus is equally shared between metal layers optimization (e.g. fabrication method, oxide management) and process optimization.The SLID bonding process studies were focusing on the Cu–In–Sn, Au–In and Bi–In material systems. It was demonstrated that electrical interconnections can be fabricated at bonding temperatures as low as 150°C by taking advantage of the Cu–In–Sn ternary system. The low processing temperatures allow for bonding of temperature sensitive materials and of materials with dissimilar thermo-mechanical properties by thermally induced stress management. Microstructural characterization confirmed the high bonding quality with low amount of defects in interconnections composed of a layered Cu / intermetallic / Cu structure, with a single-phase intermetallic Cu6(Sn,In)5 phase. Moreover, the mechanical testing shows that the bonds have tensile strength above 30 MPa.Au–In SLID bonding can be performed at temperatures slightly higher than the In melting temperature of 156°C. Successful bonds were demonstrated at 180°C. The resulting intermetallic bonding layer has a remelting temperature >450°C and a high shear strength above 30 MPa both at room temperature and 300°C.Another system studied was Au–In–Bi, utilizing the low eutectic point of In–Bi (72oC). Bonds at temperatures of 90 °C were proven. However, in order to consume the various In–Bi intermetallics with low melting temperatures (T< 110 oC), a bonding temperature higher than 110 oC should be used for a reliable result. We have demonstrated such SLID bonds at 115 oC, with a bond line consisting of Au / Au–In IMCs / Au, with Bi inclusions. All these materials have melting temperatures > 271 oC, with the bonding layer being stable at 450 oC if Bi does not form continuous structures.The study of metal TC bonding is reporting recent developments on the optimization of Cu-Cu and Al-Al wafer bonding. To decrease the bonding temperature of Cu-Cu TC bonding, Cu layers fabrication and oxide management are essential. By using certain surface pre-treatment methods such as plasma and self-assembled monolayer (SAM), Cu-Cu low temperature bonding was investigated. Various plasma concentrations were used to investigate the influence of plasma composition on bond strength.Further investigations were performed on the impact of different morphological Cu-properties and their effects on the bonding yield. The comparison of the interdiffusion behavior of layers deposited using different methods (e.g. physical vapor deposition - PVD Cu vs. electroplated - ECD Cu), as well as different surface preparation methods is being reported here. Different surface treatments like in-situ and ex-situ oxide management, as well as pre-bond CMP processes were tested in combination with the respective deposition methods. By combining the most effective sample and process parameters, the necessary bonding temperature for a successful Cu-Cu TC bonding could be reduced to temperatures of 175°C. The successful interdiffusion behavior at such low temperatures was confirmed by cross section TEM measurements.Apart from Cu, Aluminum is widely used material, due to its good electrical conductivity and compatibility with CMOS processes. Aluminum has a very stable native oxide and therefore high temperature and pressure are necessary to generate a successful Al-Al bond at wafer-level. The low temperature Al-Al TC bonding using a thin Palladium passivation layer at 350°C is reported here. The thermo-compression bonding was performed on both blank and patterned wafers.This work is reviewing recent achievements in the reduction of metal wafer bonding process temperature to less than 200°C based on the mechanical, structural and electrical characterization of the metal bonding layers.

Influence of Artificially Altered Engine Oil on Tribofilm Formation and Wear Behaviour of Grey Cast Cylinder Liners

This work investigates the influence of altered engine oil on the tribological performance, focusing in particular on wear and interconnected tribofilm formation. For this purpose, Zinc dialkyldithiophosphate (ZDDP) additivated engine oils of different degradation levels, produced in an artificial oil alteration process, were used in tribometer tests with a nitride steel piston ring against a grey cast iron cylinder liner model contact. Parameters were chosen to simulate the boundary and mixed lubrication regime typical for the top dead centre conditions of an internal combustion engine of a passenger car. Wear of the cylinder liner specimens was continuously monitored during the tribometer tests by the radio-isotope concentration (RIC) method, and tribofilms were posteriorly investigated by X-ray photoelectron spectroscopy (XPS). The results clearly show that the steady-state wear rates for experiments with altered lubricants were significantly lower than for the experiments with fresh lubricants. XPS analysis on the formed tribofilms revealed a decrease in sulphide and an increase in sulphate states for altered oils evaluated at 120 °C oil temperature, correlating with a decrease in steady-state wear rate. This finding emphasizes the role of sulphate species in the tribofilm formation process and its anti-wear capabilities, in contrast to the sulphide species and the (poly-)phosphate species, as outlined in most of the ZDDP literature. Moreover, the RIC signal that represents the amount of wear in the engine oil showed a decrease over time for specific altered lubricants and test conditions. These “negative” trends in the wear signal are remarkable and have been identified as an incorporation of wear particles from the lubricant into the tribofilm. This finding is supported by XPS results that detected an iron-oxide layer with a remarkably similar quantity within the tribofilm on the surface. Based on these findings, an assessment of the minimum film formation rate and particle incorporation rate was achieved, which is an important basis for adequate tribofilm formation and wear models.

Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration

An overview of various low temperature (<200°C) wafer bonding processes using metal interlayers is presented. Such processes are very attractive for novel applications in 3D heterogenous packaging as the allow for simultaneous formation of electrical interconnects, as well as hermetic encapsulation of various sensors and microelectromechanical systems-based devices. Metal wafer bonding is a generic category of processes consisting of various sub-categories, each one defined by the different principles governing the process. One can differentiate between eutectic wafer bonding (a eutectic alloy is formed as bonding layer during the process by liquid-solid interdiffusion), intermetallic wafer bonding (an intermetallic alloy is formed as bonding layer during the process by solid-liquid interdiffusion, process known also as Solid Liquid Intermetallic Diffusion – SLID or Transient Liquid Phase – TLP), and metal thermo-compression (TC) wafer bonding. Different critical/gating parameters were investigated and their impact for generally reducing processing temperatures for the different metal bonding systems was studied.

Local and high‐strength joining of transparent glass and glass‐ceramics by femtosecond Bessel beam

AbstractThe creation of robust joint among different materials with notably different coefficients of thermal expansion (CTE) is an urgent task for the development of the engineering, laser technology, and aerospace industry. In this regard, femtosecond laser welding is a promising technique for efficient adhesion‐free bonding of transparent materials. This paper reports on the laser welding of laser phosphate glass (CTE = 110 × 10−7 K−1) and spinel‐based glass–ceramic (CTE = 50 × 10−7 K−1) by the Bessel beam. Dependencies of weld geometric parameters on the pulse energy and scanning speed were investigated, and the laser exposure conditions were optimized for durable welding. The weld joints were tested on shear strength, which was shown to be as record high as up to 147 MPa. Atomic force microscopy, Raman spectroscopy, and elemental analysis were used to investigate the structure and morphology of the weld after its fracture, which revealed the laser‐induced amorphization of glass–ceramics and the formation of strong interconnection by laser‐driven mutual diffusion of two glassy phases. The results demonstrate the prospects for using femtosecond lasers for efficient industrial welding of a wide range of materials.

Alkali Wet Chemicals for Ru with Advanced Semiconductor Technology Nodes

Wet chemicals for ruthenium (Ru) etching are required for the formation of reliable Ru interconnects in advanced semiconductor technology nodes. In the present study, a novel alkali wet etchant, referred to as TK-1, has been developed in order to overcome issues with conventional Ru etchants, such as a low etch rate and the formation of toxic RuO4 gas. Regardless of the Ru deposition process, TK-1 exhibits a high Ru etching selectivity of greater than 100 relative to dielectric and liner materials. It also suppresses the production of RuO4 during the etching process. TK-1 has potential applications for Ru recess etching during fully self-aligned via fabrication.

Gamma-induced interconnected networks in microporous activated carbons from palm petiole under NaNO3 oxidizing environment towards high-performance electric double layer capacitors (EDLCs)

Activated carbons (ACs) were developed from palm petiole via a new eco-friendly method composed of highly diluted H2SO4 hydrothermal carbonization and low-concentration KOH-activating pyrolysis followed by gamma-induced surface modification under NaNO3 oxidizing environment. The prepared graphitic carbons were subsequently used as an active material for supercapacitor electrodes. The physiochemical properties of the ACs were characterized using field emission scanning electron microscope–energy dispersive X-ray spectroscopy, N2 adsorption/desorption isotherms with Brunauer–Emmett–Teller surface area analysis, Fourier transform infrared spectroscopy, X-ray diffraction and Raman spectroscopy. The electrochemical performance of the fabricated electrodes was investigated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. Even treated with extremely low H2SO4 concentration and small KOH:hydrochar ratio, the maximum SBET of 1365 m2 g−1 for an AC was obtained after gamma irradiation. This was attributed to radiation-induced interconnected network formation generating micropores within the material structure. The supercapacitor electrodes exhibited electric double-layer capacitance giving the highest specific capacitance of 309 F g−1 as well as excellent cycle stability within 10,000 cycles. The promising results strongly ensure high possibility of the eco-friendly method application in supercapacitor material production.

Conductivity Enhancement of Graphene and Graphene Derivatives by Silver Nanoparticles

In this article, a facile way for the doping of graphene and graphene derivatives with silver nanoparticles at different Ag ratios is described. Ag nanoparticles were formed directly on the surface of two different graphene substrates dispersed in dimethylformamide by the reduction of Ag cations with NaBH4. A few layered graphene nanosheets (FLG) produced from graphite and reduced graphene oxide functionalized with amino arylsulfonates (f-rGO) were used as substrates. The final graphene/Ag nanoparticle hybrid in the form of solid, dense spots showed enhanced electrical conductivity, which can be attributed to the formation of conductive interconnections between the 2D nanosheets. Importantly, electrical conductivities of 20 and 167 103 S m−1 were measured for the hybrids of f-rGO and FLG, respectively, with the higher Ag percentage without an annealing process. A representative hybrid f-rGO with Ag nanoparticles was used for the development of a highly conductive water-based gravure ink with excellent printing properties.

Maskless direct write lithography for 3D wafer-level-system-integration

This publication presents lithography results for 3D wafer-level system integration applications using a reticle free maskless lithography system VPG+ 400 from Heidelberg Instruments. The focus is on high density Cu redistribution layer (RDL) formation with &lt;2µm L/S used in polymer RDL stacks, overlay accuracy determination better than ±150nm and hybrid bond interconnect formation for 2µm interconnects, all processed on 300mm wafer size substrates.

Integrin binding peptides facilitate growth and interconnected vascular-like network formation of rat primary cortical vascular endothelial cells in vitro.

Neovascularization and angiogenesis in the brain are important physiological processes for normal brain development and repair/regeneration following insults. Integrins are cell surface adhesion receptors mediating important function of cells such as survival, growth and development during tissue organization, differentiation and organogenesis. In this study, we used an integrin-binding array platform to identify the important types of integrins and their binding peptides that facilitate adhesion, growth, development, and vascular-like network formation of rat primary brain microvascular endothelial cells. Brain microvascular endothelial cells were isolated from rat brain on post-natal day 7. Cells were cultured in a custom-designed integrin array system containing short synthetic peptides binding to 16 types of integrins commonly expressed on cells in vertebrates. After 7 days of culture, the brain microvascular endothelial cells were processed for immunostaining with markers for endothelial cells including von Willibrand factor and platelet endothelial cell adhesion molecule. 5-Bromo-2'-dexoyuridine was added to the culture at 48 hours prior to fixation to assess cell proliferation. Among 16 integrins tested, we found that α5β1, αvβ5 and αvβ8 greatly promoted proliferation of endothelial cells in culture. To investigate the effect of integrin-binding peptides in promoting neovascularization and angiogenesis, the binding peptides to the above three types of integrins were immobilized to our custom-designed hydrogel in three-dimensional (3D) culture of brain microvascular endothelial cells with the addition of vascular endothelial growth factor. Following a 7-day 3D culture, the culture was fixed and processed for double labeling of phalloidin with von Willibrand factor or platelet endothelial cell adhesion molecule and assessed under confocal microscopy. In the 3D culture in hydrogels conjugated with the integrin-binding peptide, brain microvascular endothelial cells formed interconnected vascular-like network with clearly discernable lumens, which is reminiscent of brain microvascular network in vivo. With the novel integrin-binding array system, we identified the specific types of integrins on brain microvascular endothelial cells that mediate cell adhesion and growth followed by functionalizing a 3D hydrogel culture system using the binding peptides that specifically bind to the identified integrins, leading to robust growth and lumenized microvascular-like network formation of brain microvascular endothelial cells in 3D culture. This technology can be used for in vitro and in vivo vascularization of transplants or brain lesions to promote brain tissue regeneration following neurological insults.

Formation of environmental competencies of employees for the purposes of resilience and sustainable development

The relevance of the issue is due to the strengthening of demands for environmentally sound behavior on the part of all subjects of society, including business, entrepreneurs, owners, managers and employees of enterprises, and public service bodies. Goal of the issue is to identify the possibility of applying a competency-based approach to the process of developing norms, rules and psychology of behavior, work skills and habits, and a way of thinking in the spirit of special and social justice among employees. Research methods include bibliographic analysis, comparative analysis, and modeling. Results. The study revealed the possibility and feasibility of using the Adapted 5-component competency model in the practice of developing environmental competencies among employees and managers of any organizations. Conclusions. Based on the results of the study, it was concluded that the comprehensive and interconnected formation of the entire block of basic competencies in people allows to achieve the goals of sustainable and balanced development to the greatest extent, taking into account social and environmental values.

Interconnected development of intercultural competence and soft skills through tasks in foreign language education at a university

Introduction. The formation of universal competences (flexible skills) is an imperative of the modern education system, while foreign language proficiency is one of the key competences of a modern specialist. A foreign language as a subject has great potential for the interconnected development of both subject and meta-subject, universal competences. The research purpose is to analyze the textbooks and online courses that are actively used by university teachers and evaluate the structure of tasks used and their potential for the interconnected formation of intercultural competence and soft skills. Methodology and methods. Twenty-one teachers of Petrozavodsk State University took part in the survey. Criteria based on the framework of intercultural competence and soft skills were developed to evaluate learning materials. Based on the proposed criteria, six groups of tasks were identified that contribute to the interconnected development of intercultural competence and flexible skills (culturological materials; tasks for critical thinking development; tasks for information analysis and interpretation; tasks based on students’ experience; tasks for generating one’s own ideas and products; tasks for the interaction (in pairs, groups) and creation of a joint product). Results. The study showed that 85.7% of foreign language teachers of Petrozavodsk State University (Russian Federation) agree that the development of intercultural competence and soft skills is possible and necessary. However, only 42.1% of the respondents are satisfied with the quantity and quality of tasks offered in textbooks. Moreover, all respondents use additional tasks and 95.2% do it regularly or often. The analysis of the textbooks confirmed that the respondents have reason to be dissatisfied with the quantity and quality of tasks. Only 19%-25% of the tasks offered in textbooks and/or online courses can be used to develop universal competences and intercultural competence. A more detailed analysis of the tasks revealed that the least presented were tasks for creating one's own product (individually) and group tasks for creating a group product. Conclusion. The results obtained allowed to develop a classification of tasks to be used in foreign language classes at a university for the interconnected development of subject and meta-subject competences. The formulations of tasks for achieving integrated results in foreign language education were proposed.

Laser Assisted Bioprinting of laminin on biodegradable PLGA substrates: Effect on neural stem cell adhesion and differentiation

Laser Assisted Bioprinting (LAB) is recognized to be an enabling and versatile microfabrication technology for regenerative medicine and artificial tissue engineering. Current bioprinting concentrates on a layer-by-layer approach to print cells in consecutive stacks or nets, to recreate specialized tissue functions with a top-down approach. This synthering of proximal cells however reduces the long range correlation of tissue parenchyma and stroma given by natural development, as result of cells mobility and signaling. In this work, laminin, one of the main components of brain extracellular matrix is deposited by LAB on a biodegradable scaffold made of poly(lactic-co-glycolic acid) (PLGA), providing chemical cues for the adhesion and differentiation of neural stem cells NE-4C induced by retinoic acid. Surface roughness and LAB induced aggregates promote the initial adhesion of neuronal stem cells to the PLGA substrate and influence the formation of clusters and interconnection between them. The amount of laminin delivered inside the spot area may be controlled down to sub-monolayer coverage and a positive correlation between the laminin spots and soma of trafficking cells is demonstrated, also by computational modelling. Anisotropic orientation of neurite outgrowth is induced upon differentiation, up to 70% of processes protruding from stem cell clusters. The comparative analysis shows that the topological cue plays a major role in enhabling cluster formation on the scaffold, but the bioprinted laminin spots appear to be regulating the strength of connection between them, opening the way to control the functional morphology of artificial neural tissue constructs.