As the density of 3D interconnects is increasing exponentially when scaling to lower levels of the interconnect wiring, in most cases 3D interconnect pitches of 5 μm and below will be required. Dielectric wafer to wafer bonding with via last integration can offer these interconnect densities. Wafer-to-wafer alignment and its impact on via last alignment are discussed. By taking into account current alignment tolerances, via last diameters of 1μm enable 2μm pitch TSV interconnection densities. For further scaling the TSV pitch, lower wafer to wafer bonding alignment tolerance are required. Today the best wafer-to-wafer overlay accuracy is around 400nm, but developments are ongoing to reduce this tolerance further to 200nm.
The rapid growth of data bandwidth required between logic and memory chips for next generation device nodes is progressively pushing low I/O count serial busses to their limits. To further satisfy this increasing need for high data rates, wider I/O count busses are now being developed and established. Over the past years, various Fan-Out Wafer-Level-Packaging (FOWLP) approaches have been developed to answer the needs mentioned above and the increasingly demanding function integration on package. Imec has been working on a novel 300mm Fan-Out Wafer-Level-Packaging concept that enables 20μm pitch interconnect density. Results from experiments demonstrates wafer bow below 500μm after molding on silicon substrate with ultra-low die shift with maximum die to carrier mismatch below 10μm on full 300mm wafers. Further warpage and die shift evolution are expected depending on the process steps the wafers must go through and will be further discussed.
The distribution of internal resistance in most microbial electrolysis cells (MECs) remains unclear, which hinders the optimization and scaling up of the technology. In this study, a method for quantifying the effects of design and operation decisions on internal resistance was applied for the first time to MECs. In typical single chamber MECs with carbon cloth electrodes, the internal resistance was distributed as follows: 210 Ω cm2 for anode, 77 Ω cm2 for cathode, and 11 Ω cm2 M for solution. While varying the spacing of the electrodes (<1 cm) had little effect on MEC performance, inducing fluid motion between the electrodes decreased the internal resistance of all MEC components: 150 Ω cm2 for anode, 47 Ω cm2 for cathode, and 5.3 Ω cm2 M for solution. Adjusting the anode to cathode surface area ratio, to balance the internal resistance distribution, resulted in a significant improvement in performance (47 A/m2 current density, 3.7 L-H2/L-liquid volume/day). These results suggest that the quantification of the internal resistance distribution enables the efficient design and operation of MECs. The parameters obtained in this study were also capable of predicting the performance of MECs from some previous studies, demonstrating the effectiveness of this method.
Accelerating the deployment of renewable energy renewable energy (RE) is one of the most important strategies to achieve the 2060 carbon neutrality goal in China. In this context, it is crucial to understand the RE investment needs at the provincial level to better allocate resources and develop policies to facilitate RE development and deployment at the local level. In this paper, we estimate the wind and solar investment needs by Chinese provinces between 2020 and 2060 under four alternative pathways towards China’s 2060 carbon neutrality, by using a global integrated assessment model with provincial details of China combined with the most updated cost data for each province, and explicitly considering national and local investment market conditions. Results show that the average annual wind and solar investment needs are $317 billion per year between 2020 and 2060, or 2.3 percent of China’s 2020 GDP. We find large spatial and temporal variations of the needed RE investment and identify that technologies, resource endowment, and financial conditions are the three primary contributions to the regional disparity in investment needs. This study delves into the local factors constraining RE deployment in China, providing insights applicable not only to the country but also holding implications for studying global RE investment dynamics in alignment with the collective pursuit of heightened clean energy transition goals.
With the continuous development of 3D technology, il enables different variety in advanced 3D packaging. One oi the 3D package type which is currently being explored is the die-to-wafer (D2W) configuration. The 3D D2W assembly can be packaged using a standard flip chip with a laminate or BGA substrate but it has certain limitation in terms oí deformation induced during processing due to temperature changes as it is composed of different materials mainly substrates, silicon-die and mold compound with different coefficient of thermal expansions (CTE). Hypothetically. removing one of its main material component could simplify the complexity of CTE mismatch and provide better deformation control. Wafer reconstruction technique was then applied to reduce the deformation caused by the presence of BGA substrates. Meaning, the packaging main components are silicon- and mold compound only in which classify as Fan-out Wafer Level packaging (FOWLP). It provides the same functions as wafer level packaging without the use of BGA substrates. However, there are certain trade-offs particularly in molding process especially on fully stacked D2W 300 mm wafer size. Molding with large area as 300mm diameter and narrow gap around 300μm down to 50μm are part of the major challenges. One of the major concern in wafer reconstruction is the warpage problem. Warpage is commonly due to CTE mismatch between two or more different bonded materials. In this paper, the feasibility of Wafer Level Packaging wil demonstrated using the compression molding method with single and balancing wafer. The balancing wafer will be explored in terms of warpage reduction and can also act as a heat spreader. The single and balancing molded wafei warpage assessment will be then explored. Theoretically, molding compound plays a significant role in warpage aspect. The thickness of the mold compound or moldcap has significant effect in the degree of bowing of the package. The thicker the moldcap, the more severe in warpage behavior in the field of wafer molding. This paper will also demonstrate the effect of single and balancing wafer in compression molding process.
The next generations of data centers require a scalable optical transceiver technology. In this paper we present a silicon photonics platform supporting single-channel data rates of 50Gb/s and above. Advanced process options include 50GHz GeSi electro-absorption modulators, high efficiency thermo-optic phase shifters with Pπ <5mW and silicon carrier depletion-based phase-shifters supporting Mach-Zehnder and micro-ring modulators. The performance and reliability of the key library components such as modulators, detectors, fiber couplers and heaters is described.
Through Silicon Via (TSV) technology represents one key aspect of 3D integration. International Technology Roadmap for Semiconductors (ITRS) has identified a need for an in-line metrology for characterizing voids in TSV structures. We have previously described a laser-based acoustic technique which can be used to detect voids in vias. Results for 10×100 and 5×50μm via structures were reported. In this work, we report on measurements of 3×50μm vias with aspect ratio of ∼17:1. Accuracy of the laser acoustic technique is validated by comparison with cross section images obtained using focused ion beam scanning electron microscopy (FIB-SEM). Measurements typically take a few seconds per site making this non-contact, non-destructive technology an attractive option for in-line void detection.
Wafer-to-wafer (W2W) hybrid bonding has gained more attention as the Artificial intelligence (AI) and big data machine learning (ML) applications required higher interconnect densities. This paper presents our research to demonstrated Cu/SiCN W2W hybrid bonding down to PAD Pitch 700nm. We have proven good Cu-Cu connectivity performance in both long daisy chains and kelvin resistor devices. Atomic Force Microscope (AFM) measurement is used to analyze the pre-bonding materials properties, namely Cu PAD height, dielectric surface profile and roughness. This enables, together with good W2W hybrid bonding overlay control, high electrical yield.
Abstract China has large, estimated potential for direct air carbon capture and storage (DACCS) but its deployment locations and impacts at the subnational scale remain unclear. This is largely because higher spatial resolution studies on carbon dioxide removal (CDR) in China have focused mainly on bioenergy with carbon capture and storage. This study uses a spatially detailed integrated energy-economy-climate model to evaluate DACCS for 31 provinces in China as the country pursues its goal of climate neutrality by 2060. We find that DACCS could expand China’s negative emissions capacity, particularly under sustainability-minded limits on bioenergy supply that are informed by bottom-up studies. But providing low-carbon electricity for multiple GtCO 2 yr −1 DACCS may require over 600 GW of additional wind and solar capacity nationwide and comprise up to 30% of electricity demand in China’s northern provinces. Investment requirements for DACCS range from $330 to $530 billion by 2060 but could be repaid manyfold in the form of avoided mitigation costs, which DACCS deployment could reduce by up to $6 trillion over the same period. Enhanced efforts to lower residual CO 2 emissions that must be offset with CDR under a net-zero paradigm reduce but do not eliminate the use of DACCS for mitigation. For decision-makers and the energy-economy models guiding them, our results highlight the value of expanding beyond the current reliance on biomass for negative emissions in China.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)