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Rapid Prototyping Techniques for Organic Direct-Bonded-Copper Power Modules
Organic Direct-Bonded-Copper (ODBC) is a novel packaging technology for power modules which allows higher flexibility in layout design. In this work, a set of rapid prototyping techniques are developed for ODBC modules based on a polyimide dielectric material. These techniques enable fast and low-cost fabrication of modules with 3-Dimensional (3D) layout features. An example half-bridge (HB) silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) module is designed and prototyped using the proposed techniques aiming at ultra-low power loop inductance. Finite element analysis (FEA)-circuit co-simulations results and experimental results validate an approximately 0.71nH power loop inductance for the example module design.
Substrate dependence of heat dissipation in GaN p-n diodes bonded to SiC, AlN direct-bonded Cu, and diamond
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Organic Direct-Bonded-Copper-Based Rapid Prototyping for Silicon Carbide Power Module Packaging
Silicon carbide (SiC) power devices are playing ever- growing roles in high-power-density power electronics converters by offering benefits such as high voltage rating, fast transients, and high thermal performance. Organic direct-bonded copper (ODBC)-based packaging, due to its ductility and ease of han- dling, allows the possibility of a more flexible layout design that may better tap the potential of SiC benefits. In this work, an ODBC-based prototyping routine is developed that accelerates the iterations of packaging layout design with low cost. The properties of ODBC and its handling are briefly introduced, and tools and fabrication steps are explained. Following this routine, a 1.2-kV SiC half-bridge power module is designed and fabricated with the focus on sub-nanohenry ultra-low loop inductance. Simulation and experimental validation are also conducted.
Direct-bonded diamond membranes for heterogeneous quantum and electronic technologies
Diamond has superlative material properties for a broad range of quantum and electronic technologies. However, heteroepitaxial growth of single crystal diamond remains limited, impeding integration and evolution of diamond-based technologies. Here, we directly bond single-crystal diamond membranes to a wide variety of materials including silicon, fused silica, sapphire, thermal oxide, and lithium niobate. Our bonding process combines customized membrane synthesis, transfer, and dry surface functionalization, allowing for minimal contamination while providing pathways for near unity yield and scalability. We generate bonded crystalline membranes with thickness as low as 10 nm, sub-nm interfacial regions, and nanometer-scale thickness variability over 200 by 200 μm 2 areas. We measure spin coherence times T 2 for nitrogen vacancy centers in 150 nm-thick bonded membranes of up to 623 ± 21 μs, suitable for advanced quantum applications. We demonstrate multiple methods for integrating high quality factor nanophotonic cavities with the diamond heterostructures, highlighting the platform versatility in quantum photonic applications. Furthermore, we show that our ultra-thin diamond membranes are compatible with total internal reflection fluorescence (TIRF) microscopy, which enables interfacing coherent diamond quantum sensors with living cells while rejecting unwanted background luminescence. The processes demonstrated herein provide a full toolkit to synthesize heterogeneous diamond-based hybrid systems for quantum and electronic technologies.
Directional Bonding in Decaniobate Inorganic Frameworks
Abstract Metal–oxo clusters offer an opportunity to assemble inorganic and metal–organic frameworks (MOFs) by a controlled building‐block approach, which led to the revolutionary discoveries of zeolites and MOFs. Polyoxometalate clusters are soluble in water, but more challenging to link into frameworks; the inert oxo‐caps that provide solubility are resistant to replacement or further connectivity. We demonstrate how the unique directional bonding and varying basicity of the decaniobate ([Nb 10 ]) oxo‐caps can be exploited to build 1D, 2D, and 3D inorganic frameworks. In nine structures, A + (A=Li, Na, K, Rb and Cs), AE 2+ (AE=Ca, Sr, Ba) and Mn 2+ demonstrate that the dimensionality of the obtained material is controlled by cation charge and size. Increased cation charge decreases selectivity for oxo‐site bonding, leading to higher dimensional linking. Larger cation radii also decreases bonding selectivity, yielding higher dimensional materials. Ion‐exchange studies of the A + ‐Nb 10 family shows exclusive selectivity for Cs + over other alkalis, which is important for radioactive Cs removal and sequestration.
Optical magnons with dominant bond-directional exchange interactions in the honeycomb lattice iridate α — Li 2 IrO 3
We have used resonant inelastic x-ray scattering to reveal optical magnons in a honeycomb lattice iridate α - Li 2 IrO 3 . The spectrum in the energy region 20–25 meV exhibits momentum dependence, of which energy is highest at the location of the magnetic Bragg peak, ( h , k ) = ( ± 0.32 , 0 ) , and lowered toward ( 0 , 0 ) and ( ± 1 , 0 ) . We compare our data with a linear spin-wave theory based on a generic nearest-neighbor spin model. We find that a dominant bond-directional Kitaev interaction of order 20 meV is required to explain the energy scale observed in our study. The observed excitations are understood as stemming from optical magnon modes whose intensity is modulated by a structure factor, resulting in the apparent momentum dependence. We also observed diffuse magnetic scattering arising from the short-range magnetic correlation well above T N . In contrast to Na 2 IrO 3 , this diffuse scattering lacks the C 3 rotational symmetry of the honeycomb lattice, suggesting that the bond anisotropy is far from negligible in α - Li 2 IrO 3 .
An Organic, Direct Bonded Copper, Multi-Layered, Ultra-Low Inductance Package for High-Power UWBG MOSFETs
The most common metalized substrates used in high-power switching packages consist of a ceramic layer such as Aluminum Nitride (AlN) sandwiched between two copper layers. Ceramic substrates are used because it has the key characteristic of having high dielectric strength while being thermally conductive. A large drawback to ceramic substrates is that they do not allow for a multi-layered circuit design. By replacing the traditional ceramic substrate with organic direct bonded copper (ODBC) we can open a wide range of possibilities when it comes to power module layout such as multi-layered circuits and double-sided cooling. Both benefits are critical while packaging high-performance Gallium Oxide (Ga2O3) MOSFETs. Because of Ga2O3's relatively poor thermal conductivity, a double-sided cooled package becomes necessary. Therefore, the use of ODBC provides the flexibility to fabricate copper traces carrying much higher currents, and by creating a multi-layered package, we can drastically reduce the parasitic inductance inside the power module. Achieving lower parasitic inductance is critical for an ultra-fast Ga2O3 package to avoid excessive voltage overshoot and ringing. Using ODBC, we have designed novel packages capable of handling the challenges presented by fast Ga2O3 switching. Using multi-physics modeling software, we can validate our design before building the prototype. Due to the simple process parameters needed to work with ODBC, we can rapidly create prototypes without using external vendors. This flexibility allows us to quickly design, build, and validate highly complex switching power modules to accommodate next generation, Ga2O3 switching devices.
Bonding-Directed Crystallization of Ultra-Long One-Dimensional NbS 3 van der Waals Nanowires
Not Available
Simulating exotic phases of matter with bond-directed interactions with arrays of Majorana-Cooper pair boxes
It is suggested that networks of Majorana-Cooper pair boxes connected by metallic nanowirescan simulate various exotic states of matter. In this simulations Majorana-Cooper boxes play therole of effective spins S=1/2 and the metallic connections generate the Kondo screening and theRuderman-Kittel-Kasuya-Yosida (RKKY) interaction. Depending on what prevails - whether it isthe Kondo effect or the RKKY exchange, one will have either an effective spin model or a Kondolattice. The list of exotic stets includes the famous hexagonal Kitaev model, a generalization of thismodel for a Kondo lattice and various spin models with three-spin interactions. A special emphasizeis made on the discussion of the Kondo lattice scenario.
Strategies relating to CMP for die to wafer interconnects utilizing hybrid direct bonding.
Abstract not provided.
Strategies relating to CMP for die to wafer interconnects utilizing hybrid direct bonding.
Abstract not provided.
Strategies relating to CMP for die to wafer interconnects utilizing hybrid direct bonding.
Abstract not provided.
Cerium Dimer Anion and the Contribution of 4f Electrons to Lanthanide Metal–Metal Bonds
Direct metal−metal bonding between lanthanide atoms has been challenging to observe. We report on the first spectroscopic characterization of the cerium dimer anion (Ce 2 − ) and its neutral analog (Ce 2 ) in the gas phase, achieved using photoelectron and ultrafast spectroscopy combined with high-level quantum chemistry calculations. The electron affinity of Ce 2 is 0.24 eV, from which a dissociation energy of 2.21 eV is derived for Ce 2 − . The wave-packet dynamics upon photodetachment are studied and yield vibrational frequencies for electronically excited Ce 2 . Ce 2 − exhibits a conventional metal−metal triple bond with minimal contribution from 4f electrons. However, evidence of 4f-electron participation in bonding is identified for the low-energy excited states only 0.1 eV higher. The results challenge the assumption of inert 4f electrons in metal−metal bonding, and we propose a promising strategy for forming stable lanthanide−lanthanide bonds involving significant 4f-electron contributions.
Power Electronic Substrates for Space Restricted Application
High-power modules use substrates to house the semiconductor device and for electrical insulation. These substrates are constructed with thermally conductive dielectric material sandwiched between two metals to extract heat from semiconductor chips. Thus, the required cooling performance of a power module is linked to the substrate’s thermal performance and can vary based on the substrate technologies. In this study, four substrate technologies were evaluated for space-restricted applications: direct-bonded copper, an insulated metal substrate, a thermally annealed pyrolytic graphite–based insulated metal substrate, and direct-bonded aluminum, where the heat sink is directly attached without thermal interface materials. The finite element results suggest that the popular direct-bonded copper substrate has better thermal performance than the rest of the substrates for space-restricted applications. Furthermore, a modified direct-bonded copper is proposed to further improve thermal performance. The evaluation results show that the modified substrate can handle 30% more losses than its traditional counterpart.
Role of humidity and surface roughness on direct wafer bonding
Bodies made from elastically stiff material usually bind very weakly unless the surfaces are flat and extremely smooth. In direct wafer bonding flat surfaces bind by capillary bridges and by the van der Waals interaction, which act between all solid objects. Here we study the dependency of the work of adhesion on the humidity and surface roughness in hydrophilic direct wafer bonding. We show that the long-wavelength roughness (usually denoted waviness) has a negligible influence on the strength of wafer bonding (the work of adhesion) from the menisci that form from capillary condensation of water vapor.
Crystal Engineering of Hydrogen Bonding for Direct Air Capture of CO2: A Quantum Crystallography Perspective
Rising atmospheric CO2 levels demand efficient and sustainable carbon capture solutions. Direct air capture (DAC) via crystallizing hydrogen-bonded frameworks such as carbonate salts has emerged as a promising approach. This review explores the potential of crystal engineering, in tandem with advanced quantum crystallography techniques and computational modeling, to unlock the full potential of DAC materials. We examine the critical role of hydrogen bonding and other noncovalent interactions within a family of bis-guanidines that governs the formation of carbonate salts with high CO2 capture capacity and low regeneration energies for utilization. Quantum crystallography and charge density analysis prove instrumental in elucidating these interactions. A case study of a highly insoluble carbonate salt of a 2,6-pyridine-bis-(iminoguanidine) exemplifies the effectiveness of these approaches. However, challenges remain in the systematic and precise determination of hydrogen atom positions and atomic displacement parameters within DAC materials using quantum crystallography, and limitations persist in the accuracy of current energy estimation models for hydrogen bonding interactions. Future directions lie in exploring diverse functional groups, designing advanced hydrogen-bonded frameworks, and seamlessly integrating experimental and computational modeling with machine learning. This synergistic approach promises to propel the design and optimization of DAC materials, paving the way for a more sustainable future.
A Modified DBC Substrate Improving Thermal Performance for Confined Space Applications
High-power modules use substrates to house the semiconductor device and for electrical insulation. These substrates are constructed with thermally conductive dielectric material sandwiched between two metals to extract heat from semiconductor chips. Thus, the required cooling performance of a power module is linked to the substrate’s thermal performance and can vary based on the substrate technologies. Here, in this study, five substrate technologies were evaluated for space-restricted applications: direct-bonded copper (DBC), an insulated metal substrate (IMS), a thermally annealed pyrolytic graphite (TPG)-based IMS, DBC-based double-sided cooling, and direct-bonded aluminum (DBA) where the heat sink is directly attached without thermal interface materials (TIMs). The finite element (FE) analysis results suggest that the popular DBC substrate has thermal performance better than that of the other substrates for space-constrained applications. To further improve the thermal performance, a modified DBC substrate was proposed where a copper block was added between the semiconductor and the DBC substrate to achieve heat spreading underneath the chip. The modified DBC performance was then compared with the aforementioned substrates and the results showed significant thermal performance improvement. The results were verified with experimental results where the proposed substrate showed 20% more loss handling capability compared to an identical DBC substrate.