Integration Of Microelectronics Research Articles

Thermosetting boron-nitride-filled polybutadiene composites with enhanced thermal conductivity and good dielectric properties

Low dielectric materials with high heat dissipation, low dielectric constant (Dk), and dielectric loss (Df) are urgently needed to address the issues of signal cross-talk and heat accumulation arising from the rapid development of modern communication technology and the integration of microelectronics. Polyolefins, as hydrocarbon polymers, have shown significant potential due to their excellent low dielectric properties. However, their low polarity and flexible structures limit their thermal conductivity and thermomechanical properties. In this study, we developed a method to prepare thermosetting polybutadiene composites with enhanced thermal conductivity and good dielectric performance by modifying hexagonal boron nitride (h-BN) and hydroxyl-terminated polybutadiene (HTPB) with thermally cross-linkable benzocyclobutene (BCB) groups. The properties of the resulting composites were tailored by varying the filler content. With 30 wt% of the BCB-modified filler, the composite (HB-30) displayed excellent dielectric properties (Dk = 2.70; Df = 1.67 × 10−3 @10 GHz). Meanwhile, it exhibited a thermal conductivity of 0.615 W/mK at 35 °C, which was 7.1 times that of pristine HTPB. It also showed significantly enhanced mechanical properties and thermal stability with a storage modulus of 2.7 GPa and a glass transition temperature (Tg) of 208.5 °C. This method proved effective for preparing polymer composites with enhanced thermal conductivity, heat resistance, mechanical properties and good dielectric properties, making them suitable for high-frequency communication applications.

Enhanced thermal performance of hybrid interface materials supported by 3D thermally conductive SiC framework

The rapid development of microelectronic integration technology is placing increasing demands on the safety performance of electronic devices. Excellent thermal interface materials (TIM) facilitate the dissipation of heat from electronic components, which ensures the safety of electronic equipment. In this work, a three-dimensional (3D) thermally conductive framework is constructed from carbon fibers to form silicon carbide (SiC) in situ. This is followed by vacuum impregnation with paraffin wax (PW) to produce phase change composites (PCCs). The results show that the SiC-based 3D thermally conductive framework has a hierarchical porous network structure, and the PCC indicates enhanced thermal conductivity and good anti-leakage properties. The thermal conductivity of PW @ CF1–Si1-1550 is 0.81 W K−1m−1, which is 4 times that of PW. In addition, the PCC also shows good thermal cycling properties, high thermal storage capacity (179.06 Jg-1), and good insulation properties. The PCC as described in this paper as TIM have considerable application potential in thermal management.

Recent Progress on Yarn‐Based Electronics: From Material and Device Design to Multifunctional Applications

AbstractOver the last decade, the rapid development of wearable electronics has generated renewed interest in textiles. The integration of advanced nanotechnology and microelectronics with well‐established textile production processes has resulted in textile electronics, that are lightweight, flexible, breathable, and conformable, which broadens the applications of electronic products. The hierarchical textile structure, ranging from a single fiber to twisted yarns and various fabrics, is suitable for constructing multifunctional flexible devices. In particular, yarn, which bridges between fiber and fabric, is advantageous owing to its easy integration into wearable formats via weaving, knitting, or braiding. However, because of the dearth of effective interdisciplinary communication between researchers of electronic and textile engineering, fabricating yarn‐based devices with superior mechanical properties and versatile electronic functionality is difficult. Therefore, this review provides an overview of yarn‐based electronics, followed by a systematical summary of recent progress in yarns with respect to material and device design, multifunctional integration, and applications in wearable devices, including sensors, actuators, stealth, batteries, and nanogenerators. Furthermore, the major challenges and future developments in this field are discussed.

Multifunctional boron nitride nanosheets cured epoxy resins with highly thermal conductivity and enhanced flame retardancy for thermal management applications

With the rapid improvement of microelectronics integration and assembly technology, the increasing heat flux density in electronic devices puts forward higher requirements for efficient heat dissipation and fire safety of thermal management materials (TMMS). In this work, we proposed a facile method to exfoliate and organically modify hexagonal boron nitride (h-BN) via phytic acid assisted-ball milling and self-assembly of zeolitic imidazolate frameworks (ZIF-8). And the obtained multifunctional additive (BAZF) successfully achieved the synergistic integration of highly thermal conductivity and superior fire safety in epoxy resin (EP). Besides, BAZF was also utilized as a curing agent to initiate the crosslinking reaction of EP, and the activation energy (Eα) and kinetic parameters of curing process were obtained by the fitting of Kissinger and Crane equation. Compared to EP, the peak heat release rate (PHRR), smoke production rate (SPR) of EP composites containing 16 wt% BAZF significantly reduced by 58.2% and 47.7%, respectively, showing superior flame retardancy. Contributed by the good compatibility between fillers and matrix, BAZF significantly enhanced the thermal conductivity and mechanical properties of EP composites. As a result, this work provides a cost-effective route for the preparation of epoxy-based TMMS, which shows significant potential application in modern microelectronic industry.

ELECTROCHEMICAL BIOSENSORS FOR CONT­ROL OF LEAD CONTENT IN THE ENVIRONMENT. A REVIEW

The review presents different types of biosensors and their principles of operation that are currently used to detect heavy metals and lead. Biosensors are considered highly sensitive, specific, accurate, inexpensive and effective tools for the preliminary detection of one or more metals in sources of mixed pollution, especially in wastewater. The use of functional nanomaterials based on metal-organic frameworks and layered hydroxides allowed to miniaturize the design of biosensors and significantly improve their applicability for on-site analysis of target samples, which reduces the probability of any changes in the samples during transport to the laboratory. Also, these materials have long-term stability, improve the signal and response speed of electrochemical biosensors, and also increase their sensitivity and selectivity. An overview of the methods of manufacturing the active component of multilayer electrochemical sensors was conducted. The main methods of obtaining stable and sensitive to lead ions electrochemical systems are noted.Sensors and biosensors are powerful tools for accurate qualitative and quantitative analysis of a specific analyte and integration of biotechnology, microelectronics, and nanotechnology to fabricate miniaturized devices without loss of sensitivity, specificity, and cont­rol accuracy. The characteristic properties of biomolecule carriers significantly affect the sensitivity and selectivity of the device. The impact of carriers based on metal-organic frameworks and layered hydroxides on increasing the efficiency of modern lead biosensors due to the implementation of the enzyme inhibition mechanism was considered, and the me­thods of manufacturing the active component of multilayer electrochemical sensors were also reviewed. The perspective of using the coprecipitation method and the ion exchange method to obtain stable and sensitive lead ion electrochemical systems was noted. Thus, electrochemical biosensors can be considered as one of the most widely developed biosensors for the detection of lead ions, in which the presence of direct electron transfer from the recognition center to the electrode reduces the probability of unnecessary interference, which significantly increases their sensitivity and selectivity and enables the development of devices for in-mode monitoring real-time.

Practice and Exploration of Mixed Teaching of Microelectronics

The mixed teaching mode plays an increasingly important role in stimulating students’ interest and autonomy in learning, and strengthening students’ learning ability. The full integration of mixed teaching mode and microelectronics teaching can not only achieve the teaching objectives smoothly, but also enable students to deepen their understanding and memory of relevant knowledge with the help of diversified and interesting teaching methods. Therefore, this paper takes the microelectronics course as an example to practice and explore the effective ways to carry out the mixed teaching mode. Teachers should not make full use of online and offline teaching resources, but also actively improve the traditional assessment systems. Through the continuous improvement of the practicality of online and offline teaching content, an easy-to-complex teaching method with a coherent content structure can be adopted to stimulate students’ learning motivation, improve their enthusiasm for participation, and lay a solid foundation for further improvements in the teaching of microelectronics technology.

Highly thermal conductivity of PVA-based nanocomposites by constructing MWCNT-BNNS conductive paths

The development of modern microelectronic devices and chip integration cause electronics devices to generate excessive heat. To overcome such challenges in the near future, designing thermally conductive composites with improved stability, conductivity, and excellent electric insulation properties is critical. In this study, a novel strategy was proposed to construct superior thermally conductive networks with boron nitride nanosheets-Multiwalled carbon nanotubes (BNNS-MWCNT)/ poly(vinyl alcohol) (PVA) nanocomposites through the electrospinning technique and hot-pressing process. BNNS and MWCNT are aligned along with the fiber orientation, and MWCNT, with high length-to-diameter ratio characteristics, can act as a bridging point for uncontacted BNNS. Interestingly, when the mass fraction of BNNS-MWCNT was 20 % and the mass ratio between the BNNS: MWCNT was maintained as 9:1, the resultant BNNS-MWCNT/PVA nanocomposites exhibited an excellent in-plane thermal conductivity of 11.49 W/(m·K) and observed a tremendous heat dissipation capacity than PVA and BNNS/PVA composites. Moreover, the BNNS-MWCNT/PVA recorded excellent electrical insulation properties. The present work provides inspiration for the preparation of composites with low fillers and high thermal conductivity.

Biomedical applications of microfluidic devices: Achievements and challenges

AbstractThere has been a recent interest in microfluidics due to their wide application and unique integration of concepts, including physics, materials science, chemistry, microelectronics, and biology. Microfluidic chips can be applied in different fields, particularly in the biomedical sector, such as drug delivery, diagnosis devices, cell culture, and scaffold fabrication. Various materials, including metals, polymers, and ceramics, can be manufactured into microscale chips with channels and chambers. Platforms of any required size, structure, or geometry can be fabricated using a wide range of fabrication techniques, for example, three‐dimensional printing. This manuscript assesses the microfluidic devices starting from their historical development, materials, fabrication methods and challenges, as well as biomedical applications.

The combination of AlN and h‐BN for enhancing the thermal conductivity of thermoplastic polyurethane composites prepared by selective laser sintering

AbstractIn recent years, with the rapid development of 5G communication technology and microelectronic chip integration technology, smart wearable devices with high thermal conductivity are becoming more and more important. The most common method to improve the thermal conductivity of polymers is to introduce fillers with high thermal conductivity for compounding and build a thermal conductivity network inside the system. At present, the main methods of preparing heat‐conducting composites are hot pressing molding, injection molding, and casting molding, but these traditional molding processes are difficult to prepare heat‐conducting composites with complex shapes and structures. Selective laser sintering (SLS) is a new 3D printing technology, which uses the energy provided by laser to melt polymer powder, then sinter layer by layer, stack layer by layer, and finally form printed products. Compared with the traditional molding process, the SLS process has the advantages of a simple manufacturing process, high molding precision, recyclable materials, and wide application, which can realize the design and development of complex structural parts. In this study, TPU composites were successfully prepared by using thermoplastic polyurethane (TPU) polymer as matrix material, AlN and h‐BN as thermally conductive fillers, and SLS technology. When the content of AlN is 20 wt% and the content of h‐BN is 15 wt%, the thermal conductivity of TPU composite is as high as 0.90 W/mK, which is 391% higher than that of pure TPU sintered parts. At this time, the tensile strength of the composite is 17.2 MPa and the elongation at break is 301%, and it still shows good mechanical properties. This work is devoted to proposing a preparation method of flexible and high thermal conductivity composite materials, which can be used to prepare thermal management materials with complex shapes and structures and carriers of smart wearable devices, and has broad application prospects.

Plasma enhanced light emission from the Si+-N+ co-implanted SOI in the violet-blue waveband

Silicon (Si) has been established for a long time as the footing stone of the whole microelectronics industry. This does not come into true in the photonics domain yet, where the limited degrees of freedom in material design and the indirect bandgap are the major constraints. Therefore, making Si as an efficient light-emitting material is an important approach for Si photonics, even for achieving the all-Si-based photoelectronic and microelectronic integration engineering. Here we reported a facile and effective method for enhancing the photoluminescence (PL) from the Si+/N+ ion co-implanted Si film by coating the polystyrene (PS)-sphere@metal complex core-shell structure upon the Si film on insulator (SOI) wafers. The PL enhanced phenomena have been demonstrated in the violet-blue waveband by the three kinds of single-layer PS sphere array capping with different metal films (namely Ag, Au, and Al), respectively. The experiments and theoretic calculation based on the finite difference time domain (FDTD) model indicate that the plasma resonance is responsible for the PL enhancement, and these core-shell structures take advantage of both metal plasma and photonic crystal in the PL enhancing process.

Hydrophobic Films Surface Preparation And Its Impact On Wet Cleaning

The cleaning of hydrophobic films is a key challenge for yield. Such films are prone to drying marks formation during aqueous cleaning steps. In the present work, we study how surface preparation can break non-polar bonds, resulting in a hydrophilic surface. Several treatments (ultraviolet, Standard Clean 1 and ozonated water) and materials (amorphous carbon, silicon carbon nitride) have been studied. A specific work on Silicon carbon nitride surface modification with ozonated water has been initiated with X-ray photoelectron spectroscopy. We have evaluated the interest that such step has prior to aqueous wafer cleaning and the possible consequences on electrical properties and surface energy. Further investigations will be required to evaluate the impact and interest of such a step on microelectronic process integration.

Palladium Chemical Mechanical Planarization in Packaging and Barrier Level Integration

Palladium (Pd) is a chemically inert material known for its ability to improve processing cost and reliability for the packaging level microelectronics integration. In addition, it is used as a sacrificial layer for copper (Cu) integration as a barrier material to protect the copper from oxidation. Successful implementation of Pd requires chemical mechanical planarization (CMP) process in both applications, where selectivity is desired between the Cu, tantalum nitride (TaN), and nitride (Ni) films against Pd. This paper focuses on removal rate selectivity tuning for Pd thin films in a commercial silica-based Cu-CMP slurry compared to a baseline silica slurry as a function of the slurry temperature. Detailed analyses of the integrated materials are presented, investigating the effect of temperature on surface wettability and CMP selectivity. Pd passivation is also presented by electrochemical analysis in the presence of an oxidizer for the selected polishing slurries. It is observed that lowering the slurry temperature promotes palladium CMP removal rate selectivity against Ni, Cu, and TaN by modifying slurry viscosity and wafer surface wettability with no detrimental effect observed on the surface defectivity.

Characteristics of Cracking Failure in Microbump Joints for 3D Chip-on-Chip Interconnections under Drop Impact.

With the rapid development of microelectronics packaging and integration, the failure risk of micro-solder joints in packaging structure caused by impact load has been increasingly concerning. However, the failure mechanism and reliability performance of a Cu-pillar-based microbump joint can use little of the existing research on board-level solder joints as reference, due to the downscaling and joint structure evolution. In this study, to investigate the cracking behavior of microbump joints targeted at chip-on-chip (CoC) stacked interconnections, the CoC test samples were subjected to repeated drop tests to reveal the crack morphology. It was found that the crack causing the microbump failure first initiated at the interface between the intermetallic compound (IMC) layer and the solder, propagated along the interface for a certain length, and then deflected into the solder matrix. To further explore the crack propagation mechanism, stress intensity factor (SIF) of the crack tip at the interface between IMC and solder was calculated by contour integral method, and the effects of solder thickness and crack length were also quantitatively analyzed and combined with the crack deflection criterion. By combining the SIF with the fracture toughness of the solder–Ni interface and the solder matrix, a criterion for crack deflecting from the original propagating path was established, which can be used for prediction of critical crack length and deflection angle for the initiation of crack deflection. Finally, the relationship between solder thickness and critical deflection length and deflection angle of main crack was verified by a board level drop test, and the influence of grain structure in solder matrix on actual failure lifetime was briefly discussed.

Proposed New Framework Scheme for Path Loss in Wireless Body Area Network

Recent technical developments in wi-fi networking, microelectronic integration and programming, sensors and the Internet have enabled us to create and enforce a range of new framework schemes to fulfil the necessities of healthcare-related wireless body area network (WBAN). WBAN sensors continually screen and measure patients’ indispensable signs and symptoms, and relay them to scientific monitoring for diagnosis. WBAN has a range of applications, the most necessary of which is to help patients suffering diseases to stay alive. The quality instance is the coronary heart implant sensor, whose video display unit monitors coronary heart sign and continuously transmits it. This setup eliminates the need for patients to visit the medical doctor frequently. Instead, they can take a seat at home and acquire an analysis and prescription for the disease. Today, a sizable effort is being made to increase low-power sensors and gadgets for utility in WBAN. A new framework scheme that addresses route loss in WBAN and discusses its penalties in depth is endorsed in this paper. The new framework scheme is applied to three case scenarios to obtain parameters by measuring vital information about the human body. On-body and intrabody conversation simulations are conducted. On-body conversation findings show that the route loss between transmitter and receiver rises with growing distance and frequency

Supporting Collaborative Innovation Processes in Smart Product Value Creation Networks

The development of smart products and systems includes a dramatically growing share of non-mechanical domains like microelectronic and software. This determines fundamentally new collaboration challenges and needs for system and product developers and their industrial organizations. Besides the rising number of relevant engineering disciplines (e.g. product-related internet-based service engineering and data platform engineering), the collaboration across several disciplines needs to become more systematic and has to be based on consistent system models. Since traditional value chains are transforming into new agile and distributed value creation networks, engineering collaboration approaches and solutions also have to stronger emphasize model-based, cross-company engineering collaboration. Also, the number of engineering stakeholders involved is increasing, while at the same time stakeholders are taking on new roles and completely new players are emerging, the collaboration share also has to grow continuously. This paper introduces a generic methodical approach for modeling collaborative innovation processes in value creation networks for smart products and supporting them with information technology by using an integrated, cross-company knowledge base. The support of engineering collaboration with a generic common reference innovation process along the value creation network with a seamless transformation into the engineering phase, are part of the focused approach goals. This generic approach has been instantiated according to the specific needs of early innovation phases in the field of automotive microelectronic integration considering the whole value creation network.

Review on the Integration of Microelectronics for E-Textile.

Modern electronic textiles are moving towards flexible wearable textiles, so-called e-textiles that have micro-electronic elements embedded onto the textile fabric that can be used for varied classes of functionalities. There are different methods of integrating rigid microelectronic components into/onto textiles for the development of smart textiles, which include, but are not limited to, physical, mechanical, and chemical approaches. The integration systems must satisfy being flexible, lightweight, stretchable, and washable to offer a superior usability, comfortability, and non-intrusiveness. Furthermore, the resulting wearable garment needs to be breathable. In this review work, three levels of integration of the microelectronics into/onto the textile structures are discussed, the textile-adapted, the textile-integrated, and the textile-based integration. The textile-integrated and the textile-adapted e-textiles have failed to efficiently meet being flexible and washable. To overcome the above problems, researchers studied the integration of microelectronics into/onto textile at fiber or yarn level applying various mechanisms. Hence, a new method of integration, textile-based, has risen to the challenge due to the flexibility and washability advantages of the ultimate product. In general, the aim of this review is to provide a complete overview of the different interconnection methods of electronic components into/onto textile substrate.

Aqueous high-voltage all 3D-printed micro-supercapacitors with ultrahigh areal capacitance and energy density

With the rapid development of integrated and miniaturized electronics, the planar energy storage devices with high capacitance and energy density are in enormous demand. Hence, the advanced manufacture and fast fabrication of microscale planar energy units are of great significance. Herein, we develop aqueous planar micro-supercapacitors (MSCs) with ultrahigh areal capacitance and energy density via an efficient all-3D-printing strategy, which can directly extrude the active material ink and gel electrolyte onto the substrate to prepare electrochemical energy storage devices. Both the printed active carbon/exfoliated graphene (AC/EG) electrode ink and electrolyte gel are highly processable with outstanding conductivity (~97 S cm−1 of electrode; ~34.8 mS cm−1 of electrolyte), thus benefiting the corresponding shaping and electrochemical performances. Furthermore, the 3D-printed symmetric MSCs can be operated stably at a high voltage up to 2.0 V in water-in-salt gel electrolyte, displaying ultrahigh areal capacitance of 2381 mF cm−2 and exceptional energy density of 331 μWh cm−2, superior to previous printed micro energy units. In addition, we can further tailor the integrated 3D-printed MSCs in parallel and series with various voltage and current outputs, enabling metal-free interconnection. Therefore, our all-3D-printed MSCs place a great potential in developing high-power micro-electronics fabrication and integration.

Comparison of resonant tunneling diodes grown on freestanding GaN substrates and sapphire substrates by plasma-assisted molecular-beam epitaxy* *Project supported by the National Key R&D Program of China (Grant No. 2018YFB0406600), the National Natural Science Foundation of China (Grant Nos. 61875224, 61804163, and 61827823), Key Laboratory of Microelectronic Devices and Integration Technology, Chinese Academy of Sciences (Grant No. Y9TAQ21), Key Laboratory

AlN/GaN resonant tunneling diodes (RTDs) were grown separately on freestanding GaN (FS-GaN) substrates and sapphire substrates by plasma-assisted molecular-beam epitaxy (PA-MBE). Room temperature negative differential resistance (NDR) was obtained under forward bias for the RTDs grown on FS-GaN substrates, with the peak current densities (J p) of 175–700 kA/cm2 and peak-to-valley current ratios (PVCRs) of 1.01–1.21. Two resonant peaks were also observed for some RTDs at room temperature. The effects of two types of substrates on epitaxy quality and device performance of GaN-based RTDs were firstly investigated systematically, showing that lower dislocation densities, flatter surface morphology, and steeper heterogeneous interfaces were the key factors to achieving NDR for RTDs.

Device topological thermal management of β-Ga2O3 Schottky barrier diodes* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61925110, 61821091, 62004184, 62004186, and 51961145110), the National Key R&D Program of China (Grant Nos. 2018YFB0406504 and 2016YFA0201803), the Strategic Priority Research Program of the Chinese Academy of Sciences (CAS) (Grant No. XDB44000000), the Key Research Program of Frontier

The ultra-wide bandgap semiconductor β gallium oxide (β-Ga2O3) gives promise to low conduction loss and high power for electronic devices. However, due to the natural poor thermal conductivity of β-Ga2O3, their power devices suffer from serious self-heating effect. To overcome this problem, we emphasize on the effect of device structure on peak temperature in β-Ga2O3 Schottky barrier diodes (SBDs) using TCAD simulation and experiment. The SBD topologies including crystal orientation of β-Ga2O3, work function of Schottky metal, anode area, and thickness, were simulated in TCAD, showing that the thickness of β-Ga2O3 plays a key role in reducing the peak temperature of diodes. Hence, we fabricated β-Ga2O3 SBDs with three different thickness epitaxial layers and five different thickness substrates. The surface temperature of the diodes was measured using an infrared thermal imaging camera. The experimental results are consistent with the simulation results. Thus, our results provide a new thermal management strategy for high power β-Ga2O3 diode.

Electron Beam Patterning of Metal–Organic Frameworks

Development in patterning technique of metal–organic frameworks (MOFs) will facilitate their integration in microelectronics, but controlling the structure of MOFs at the nanoscale remains a major challenge. We demonstrate that an electron beam (e-beam) can be used to pattern a zinc-imidazolate MOF, ZIF-L, at unprecedented resolution in a direct-write lithographic approach, where the electron-irradiated MOF functions either as a positive- or negative-tone resist depending on the level of exposure and developing solvent used. Nanosheets with adjustable thickness and other nanostructures can be obtained using a low e-beam with a controlled penetration depth. In addition, electron irradiation in ZIF-L leads to spatially directed crystallization to a prototypical MOF ZIF-8 via ligand-vapor treatment. This versatile strategy opens the door to e-beam-based processing of MOF materials for various applications.