Multiple Chips Research Articles

3D package thermal analysis and thermal optimization

3D packaging mainly uses TSVs (Through Silicon via) to vertically interconnect multiple chips, achieving the purpose of signal transmission and electrical connection. As a popular advanced packaging method, its research is of great significance. Although stacked chips can achieve stronger performance in smaller spaces, they can also cause a series of reliability issues, among which thermal stress and warping due to differences in the thermal expansion coefficients of materials can even lead to chip failure. Therefore, it is highly valuable to simulate and analyze the entire 3D packaging model.In this study, the thermal stress and deformation of the whole three-dimensional package model were simulated by finite element analysis. The results showed that there were significant stress and deformation effects at the joint of the TSV structure at normal temperature, and the stress and deformation reached 209.99MPa and 0.0018519mm, respectively. After that, the temperature of the double-sided package system containing 3D package under electrothermal coupling conditions was optimized by heat dissipation design, which verified the ‘quantity first’ scheme of heat dissipation fins and reduced the temperature by 40%.

Comparison of cell type and disease subset chromatin modifications in SLE.

Systemic lupus erythematosus (SLE) is an autoimmune disease with protean manifestations. There is little understanding of why some organs are specifically impacted in patients and the mechanisms of disease persistence remain unclear. While much work has been done characterizing the DNA methylation status in SLE, there is less information on histone modifications, a more dynamic epigenetic feature. This study identifies two histone marks of activation and the binding of p300 genome-wide in three cell types and three clinical subsets to better understand cell-specific effects and differences across clinical subsets. We examined 20 patients with SLE and 8 controls and found that individual chromatin marks varied considerably across T cells, B cells, and monocytes. When pathways were examined, there was far more concordance with conservation of TNF, IL-2/STAT5, and KRAS pathways across multiple cell types and ChIP data sets. Patients with cutaneous lupus and lupus nephritis generally had less dramatically altered chromatin than the general SLE group. Signals also demonstrated significant overlap with GWAS signals in a manner that did not implicate one cell type more than the others. The pathways identified by altered histone modifications and p300 binding are pathways known to be important from RNA expression studies and recognized pathogenic mechanisms of disease. NFκB and classical inflammatory pathways were strongly associated with increased peak heights across all cell types but were the highest-ranking pathway for all three antibodies in monocytes according to fgsea analysis. IL-6 Jak/STAT3 signaling was the most significant pathway association in T cells marked by H3K27ac change. Therefore, each cell type experiences the disease process distinctly although in all cases there was a strong theme of classical inflammatory pathways. Importantly, this NFκB pathway, so strongly implicated in the patients with generalized SLE, was much less impacted in monocytes when cutaneous lupus was compared to the general SLE cohort and also less impacted in lupus nephritis compared to general SLE. These studies define important cell type differences and emphasize the breadth of the inflammatory effects in SLE.

High‐speed and contactless inspection of defective micro‐LEDs through the photovoltaic effect

AbstractThe most significant challenge associated with micro‐light‐emitting‐diode (micro‐LED) displays, which are anticipated to be the next generation of display technology, is the high manufacturing cost. In order to reduce manufacturing costs, it is essential to improve yield. Improving the manufacturing yield of them necessitates the evaluation of micro‐LED chips prior to their installation onto substrates. However, the microsize and large quantity of these chips renders inspection difficult with conventional inspection methods. Herein, we propose a method for inspecting micro‐LED chips by measuring the voltage generated between the anode and cathode due to the photovoltaic effect using a developed proximity capacitance image sensor. As this inspection method does not require the use of probe pins to contact LED electrodes, it enables simultaneous inspection of multiple chips in a short time without causing any damage to the electrodes. In this paper, an experimental system equipped with this sensor was developed to demonstrate the basic measurement principle. Moreover, we demonstrated that more than 50,000 micro‐LED chips with a size of 60 μm × 34 μm can be simultaneously inspected in approximately 2 s.

Pretreatments for photoresist-patterned wafer to improve Cu pillar electrodeposition

Cu micropillars are essential components in the electronics packaging, basically connecting multiple chips. The pillars are fabricated by Cu electrodeposition that fills inside via holes formed through a photoresist (PR) layer. Unlike Damascene and TSV processes, the Cu seed layer is only opened at the bottom of via holes, while the rest of the wafer surface is covered by the PR. Therefore, additional pretreatments are required to improve the Cu electrodeposition process due to air bubbles entrapped inside PR holes, organic residues, and native oxide on Cu seed layers. This research systematically investigated the pretreatments for PR-patterned wafers. A humidifier, hot steam, and compressed water spray were assessed for surface hydration to remove air bubbles from the PR holes. Ethanol- and citric acid-based aqueous solutions were then applied to remove organic residues and native oxide from the surface of Cu seed layers. The advantages of these pretreatments were assessed by analyzing the quality of Cu electrodeposits, and the optimum methods and solutions for Cu pillar electrodeposition on the PR-patterned wafer were suggested.

An LED light propagation cavity with staggered light bars for eliminating the Hot Spot

The light source of traditional edge-lit backlight modules typically consists of LED bars which composed of multiple LED chips. However, the spacing between the chips can create distinct bright and dark spots (Hot Spot) on the input surface of the light guide plate (LGP), thereby affecting the optical performance of the backlight module. In this paper, we proposed an edge-lit backlight module with staggered light bars, incorporating a light propagation cavity design to enhance light receiving efficiency and eliminate Hot Spot. Firstly, we designed the structure of the staggered light bars and the light propagation cavity. Secondly, the advantages of the new backlight module design in eliminating Hot Spot were verified through TracePro simulations. The simulation results showed that the maximum irradiance of the backlight module reached 81,010 W/m2, and the luminance uniformity peaked at 75.142 %. Compared to the traditional backlight modules, the light receiving efficiency was increased by 6.62 %, and the luminance uniformity was improved by 1.34 times, which effectively mitigated the Hot Spot. Finally, we discussed the impact of the improved backlight module in reducing the thickness of the LGP and decreasing the number of LED chips, achieved superior optical performance. This study demonstrates the significant advantages of the light propagation cavity in eliminating Hot Spot within backlight modules.

Design of Microchannels Embedded in HTCC Substrate for Heat Dissipation of SiP With Multiple Chips

Design of Microchannels Embedded in HTCC Substrate for Heat Dissipation of SiP With Multiple Chips

Effect of Long-Term Tai Chi Therapy on the Immune-Inflammatory Pathway in Patients with Schizophrenia with Antipsychotic-Stabilized.

The primary objective of this study was to explore the influence of prolonged (24weeks) supplementary Tai Chi therapy on cognitive capabilities and immune-inflammatory pathways in subjects diagnosed with schizophrenia. A total of 90 individuals who have been clinically diagnosed with schizophrenia were assigned to two treatment groups, namely the Tai Chi treatment (TT) group and the routine treatment (RT) group. Following a 24-week duration of intervention, the data obtained from 32 patients in the TT group and 30 patients in the RT group were meticulously analyzed. At the commencement of the investigation and upon completion of the 24-week intervention, blood samples were gathered, and clinical evaluations were executed. In plasma, the identification of nine cytokines (IL-10, IFN-γ, IL-5, GM-CSF, TNF-α, IL-13, IL-4, IL-2, and IL-12) was conducted using the multiple primer suspension chip method. The clinical evaluations encompassed CGI, WHOQUOL-BREF, SOFS, PSS, BPRS, SAPS, SANS, and RBANS. In comparison to the RT group, the patients in the TT group demonstrated decreased levels of TNF-α and IL-5 (P < 0.05). Moreover, they encountered more pronounced advancements in SAPS, SANS, PSS, SOFS, and RBANS scores (P < 0.05). Additionally, a positive connection was detected between the plasma TNF-α level in the TT group and both the SANS score and the SPFS score (P < 0.05). Tai Chi has been shown to improve clinical symptoms in patients with schizophrenia as an add-on therapy, potentially through its effects on immunomodulatory pathways.

Initiation and arrest of cracks from corners in multi-chip semiconductor devices

A contemporary semiconductor device often contains multiple chips. Corners of the chips concentrate stress, and are principal sites to initiate failure. Here we propose to characterize the corners using a double cantilever beam, in which two silicon beams sandwich a row of chips. As the two beams are pulled open, a crack initiates at the corner of a chip, and runs unstably on the interface between the chip and a beam. The crack may or may not arrest, depending on various experimental conditions. We calculate energy release rate as a function of crack length by using a combination of finite element method and an analytical solution of the singular field around a corner. At a fixed applied displacement, the energy release rate is low for a short crack, peaks for a crack of intermediate length, and drops for a long crack. This non-monotonic behavior explains how a crack initiates, grows unstably, and possibly arrests. If the crack does arrest, as the two beams open further, the crack grows stably. We relate the initiation and arrest of the crack to machine compliance, specimen geometry, and flaw size. The force at which the crack initiates can be used to characterize the manufacturing process, whereas the stable growth of the crack can be used to measure interfacial toughness. It is hoped that this work will aid the development of multi-chip semiconductor devices.

An updated compendium and reevaluation of the evidence for nuclear transcription factor occupancy over the mitochondrial genome.

In most eukaryotes, mitochondrial organelles contain their own genome, usually circular, which is the remnant of the genome of the ancestral bacterial endosymbiont that gave rise to modern mitochondria. Mitochondrial genomes are dramatically reduced in their gene content due to the process of endosymbiotic gene transfer to the nucleus; as a result most mitochondrial proteins are encoded in the nucleus and imported into mitochondria. This includes the components of the dedicated mitochondrial transcription and replication systems and regulatory factors, which are entirely distinct from the information processing systems in the nucleus. However, since the 1990s several nuclear transcription factors have been reported to act in mitochondria, and previously we identified 8 human and 3 mouse transcription factors (TFs) with strong localized enrichment over the mitochondrial genome using ChIP-seq (Chromatin Immunoprecipitation) datasets from the second phase of the ENCODE (Encyclopedia of DNA Elements) Project Consortium. Here, we analyze the greatly expanded in the intervening decade ENCODE compendium of TF ChIP-seq datasets (a total of 6,153 ChIP experiments for 942 proteins, of which 763 are sequence-specific TFs) combined with interpretative deep learning models of TF occupancy to create a comprehensive compendium of nuclear TFs that show evidence of association with the mitochondrial genome. We find some evidence for chrM occupancy for 50 nuclear TFs and two other proteins, with bZIP TFs emerging as most likely to be playing a role in mitochondria. However, we also observe that in cases where the same TF has been assayed with multiple antibodies and ChIP protocols, evidence for its chrM occupancy is not always reproducible. In the light of these findings, we discuss the evidential criteria for establishing chrM occupancy and reevaluate the overall compendium of putative mitochondrial-acting nuclear TFs.

A novel thin plate spline methodology to model tissue surfaces and quantify tumor cell invasion in organ-on-chip models

Organ-on-chip (OOC) models can be useful tools for cancer drug discovery. Advances in OOC technology have led to the development of more complex assays, yet analysis of these systems does not always account for these advancements, resulting in technical challenges. A challenging task in the analysis of these two-channel microfluidic models is to define the boundary between the channels so objects moving within and between channels can be quantified. We propose a novel imaging-based application of a thin plate spline method – a generalized cubic spline that can be used to model coordinate transformations – to model a tissue boundary and define compartments for quantification of invaded objects, representing the early steps in cancer metastasis. To evaluate its performance, we applied our analytical approach to an adapted OOC developed by Emulate, Inc., utilizing a two-channel system with endothelial cells in the bottom channel and colorectal cancer (CRC) patient-derived organoids (PDOs) in the top channel. Initial application and visualization of this method revealed boundary variations due to microscope stage tilt and ridge and valley-like contours in the endothelial tissue surface. The method was functionalized into a reproducible analytical process and web tool – the Chip Invasion and Contour Analysis (ChICA) – to model the endothelial surface and quantify invading tumor cells across multiple chips. To illustrate applicability of the analytical method, we applied the tool to CRC organoid-chips seeded with two different endothelial cell types and measured distinct variations in endothelial surfaces and tumor cell invasion dynamics. Since ChICA utilizes only positional data output from imaging software, the method is applicable to and agnostic of the imaging tool and image analysis system used. The novel thin plate spline method developed in ChICA can account for variation introduced in OOC manufacturing or during the experimental workflow, can quickly and accurately measure tumor cell invasion, and can be used to explore biological mechanisms in drug discovery.

Versatile Photonic-Assisted Cognitive Radio Regulatory System Employing Joint Collaboration of Multiple Photonic Integrated Chips

Versatile Photonic-Assisted Cognitive Radio Regulatory System Employing Joint Collaboration of Multiple Photonic Integrated Chips

Exploring tunable single-wavelength detection schemes for guided-mode resonance sensors

We explore guided-mode resonant (GMR) structures in an unconventional way for low-cost yet effective bio-sensing applications. In contrast to regular broadband source-based wavelength interrogation techniques, single wavelength-based measurements can successfully eliminate the requirement of a costly spectrometer for rapid label-free detection and analysis. We have fabricated a silicon–nitride grating-waveguide structure and investigated it theoretically as well as experimentally under normal, angular, and conical incidences following an all-in-one transmission geometry. Such studies avoid unnecessary fabrication of multiple chips and promote a wide operational range of the GMR sensor. To validate the proposed cost-effective intensity-based sensing, we have analyzed our fabricated single GMR chip under different combinations of two-axis rotation to confirm its suitability under commonly available laser sources. Finally, using a He-Ne laser, a sensitivity of ∼ 166 mW/RIU is recorded experimentally on an average for the fabricated GMR device, operating at the resonant wavelength of 632.8 nm. The current study provides an in-depth investigation to promote possibilities for utilizing GMR structures in an inexpensive intensity-based bio-detection scheme through the demonstrated proof-of-concept.

Study on the Manufacturability of XDFOI Package with Organic RDLs (XDFOI-O)

The concept of chiplet has been proposed in the post Moore era, while how to achieve the layout of multiple chips of different processes and sizes in the manufacturing process is a coming problem that needs to be considered. Different layouts may significantly affect the manufacturability during the packaging process. Prospective finite element analysis (FEA) can evaluate various layouts by optimizing the layout and increasing the placement of dummy chips as stiffeners, thereby selecting the best layout and combination method. In addition, the characteristic of chiplet packaging is that multiple chips may come from different sources, such as different foundries, processes, sizes, or even thicknesses. This really poses challenges to the subsequent flip chip and wafer thinning process for leveling the total package. It is necessary to confirm the evaluation of the impact of chips with different thicknesses and underfill coverage in the process, so as to ensure the consistency in processing and improve the yield of packages.

Dynamically tuning and reconfiguring microwave bandpass filters using optical control of switching elements

AbstractWe report a novel approach for dynamically tuning and reconfiguring microwave bandpass filters (BPFs) based on optically controlled switching elements using photoconductivity modulation in semiconductors. For a prototype demonstration, a BPF circuit featuring a second‐order design using two closely coupled split‐ring resonators embedded with multiple silicon chips (as switching elements) was designed, fabricated, and characterized. The silicon chips were optically linked to fiber‐coupled laser diodes (808 nm light) for switching/modulation, enabling dynamic tuning and reconfiguring of the BPF without any complex biasing circuits. By turning on and off the two laser diodes simultaneously, the BPF response can be dynamically reconfigured between bandpass and broadband suppression. Moreover, the attenuation level of the passband can be continuously adjusted (from 0.7 to 22 dB at the center frequency of 3.03 GHz) by varying the light intensity from 0 to 40 W/cm2. The tuning/reconfiguring 3‐dB bandwidth is estimated to be ~200 kHz. In addition, the potential and limitations of the proposed approach using photoconductivity modulation are discussed. With the strong tuning/reconfiguring capability demonstrated and the great potential for high‐frequency operation, this approach holds promise for the development of more advanced tunable filters and other adaptive circuits for next‐generation sensing, imaging, and communication systems.

An inverse problem to estimate simultaneously the heat source strength for multiple integrated circuit chips on a printed circuit board

&lt;abstract&gt; &lt;p&gt;In this three-dimensional steady-state inverse heat transfer problem, we determine the magnitude of the spatially dependent volumetric heat source originating from multiple encapsulated chips mounted on a printed circuit board (PCB). Prior to the estimations, the functional form of the multiple heat sources is treated as unknown, leading to its classification as a function estimation challenge within the realm of inverse problems. The utilization of the conjugate gradient method (CGM) as an optimization tool is rooted in its distinct advantage of not requiring any a priori knowledge regarding the functional form of the unidentified quantities. Furthermore, the CGM empowers the simultaneous correction and estimation of multiple unknowns during each iteration, thereby ensuring the consistent possibility of precise estimates.&lt;/p&gt; &lt;p&gt;To affirm the precision of the estimated heat source attributed to multiple chips, a series of numerical experiments were conducted. These experiments encompassed varying inlet air velocities and introduced measurement errors. Notably, the results revealed that meticulous measurements consistently yielded accurate heat generation assessments for the chips, regardless of the prevailing air velocity conditions. The findings underscored that the accuracy of chip heat generation estimates diminished as measurement errors escalated, predominantly due to the ill-posed nature inherent in the inverse problem.&lt;/p&gt; &lt;/abstract&gt;

Nitidine chloride inhibits G2/M phase by regulating the p53/14-3-3 Sigma/CDK1 axis for hepatocellular carcinoma treatment

BackgroundLiver cancer had become the sixth most common cancer. Nitidine chloride (NC) has demonstrated promising anti-HCC properties; however, further elucidation of its mechanism of action is necessary. MethodsThe anti-HCC targets of NC were identified through the utilization of multiple databases and ChIPs data analysis. The GO and KEGG analyses to determine the specific pathway affected by NC. The Huh 7 and Hep G2 cells were subjected to a 24-h treatment with NC, followed by evaluating the impact of NC on cell proliferation and cell cycle. The involvement of the p53/14-3-3 Sigma/CDK1 axis in HCC cells was confirmed by qPCR and WB analysis of the corresponding genes and proteins. ResultsThe GO and KEGG analysis showed the targets were related to cell cycle and p53 signaling pathways. In vitro experiments showed that NC significantly inhibited the proliferation of HCC cells and induced G2/M phase arrest. In addition, qPCR and WB experiments showed that the expression of p53 in HCC cells increased after NC intervention, while the expression of 14-3-3 Sigma and CDK1 decreased. ConclusionNC can inhibit the proliferation of HCC cells and induce G2/M cell cycle arrest, potentially by regulating the p53/14-3-3 Sigma/CDK1 axis.

Study on the Manufacturability of X Dimension Fan Out Integration Package with Organic RDLs (XDFOI-O)

The concept of chiplet was proposed in the post- Moore era. How to layout the multiple chips with different processes and sizes in the package structure is a problem that needs to be considered as different layouts may significantly affect the manufacturability during the packaging process. XDFOI-O is a 2.5D organic interposer structure with a significant coefficient of thermal expansion mismatch in it. Different layouts may cause excessive stress concentration in the package structure, as well as large wafer warpage, which can affect the normal operations of the production line. Stress accumulation on specific chiplet during the wafer thinning process is another manufacturability problem, leading to chip cracking. Prospective finite element analysis can be applied to evaluate the various layouts. In simulation work, different placement processes of dummy chips as stiffeners, as well as different chiplet thicknesses and underfill coverage, can be used as factors for simulation studies, thereby making a reference for further chiplet package design.

Accelerating science: The usage of commercial clouds in ATLAS Distributed Computing

The ATLAS experiment at CERN is one of the largest scientific machines built to date and will have ever growing computing needs as the Large Hadron Collider collects an increasingly larger volume of data over the next 20 years. ATLAS is conducting R&amp;D projects on Amazon Web Services and Google Cloud as complementary resources for distributed computing, focusing on some of the key features of commercial clouds: lightweight operation, elasticity and availability of multiple chip architectures. The proof of concept phases have concluded with the cloud-native, vendoragnostic integration with the experiment’s data and workload management frameworks. Google Cloud has been used to evaluate elastic batch computing, ramping up ephemeral clusters of up to O(100k) cores to process tasks requiring quick turnaround. Amazon Web Services has been exploited for the successful physics validation of the Athena simulation software on ARM processors. We have also set up an interactive facility for physics analysis allowing endusers to spin up private, on-demand clusters for parallel computing with up to 4 000 cores, or run GPU enabled notebooks and jobs for machine learning applications. The success of the proof of concept phases has led to the extension of the Google Cloud project, where ATLAS will study the total cost of ownership of a production cloud site during 15 months with 10k cores on average, fully integrated with distributed grid computing resources and continue the R&amp;D projects.

Computational Study of the Coupling Performances for a Long-Distance Vertical Grating Coupler

We present a high-efficiency silicon grating coupler design based on a left–right mirror-symmetric grating and a metal mirror. The coupler achieves nearly perfect 90-degree vertical coupling. When two SOI chips are placed face to face with a vertical working distance of 50 μm, the chip-to-chip interlayer coupling efficiency reaches as high as 96%. When the vertical working distance ranges from 45 μm to 55 μm, the coupling loss remains below 1 dB. We also verified the effectiveness of our designed vertical coupler through 3D FDTD full-model simulation. The results demonstrate that our proposed vertical coupling structure represents a high-efficiency solution for 3D optical interconnects. The integration of multiple photonic chips in a 3D package with vertical optical and electrical interconnects is also feasible in the foreseeable future.

Characterizing Multi-Chip GPU Data Sharing

Multi-chip Graphics Processing Unit (GPU) systems are critical to scale performance beyond a single GPU chip for a wide variety of important emerging applications. A key challenge for multi-chip GPUs, though, is how to overcome the bandwidth gap between inter-chip and intra-chip communication. Accesses to shared data, i.e., data accessed by multiple chips, pose a major performance challenge as they incur remote memory accesses possibly congesting the inter-chip links and degrading overall system performance. This article characterizes the shared dataset in multi-chip GPUs in terms of (1) truly versus falsely shared data, (2) how the shared dataset scales with input size, (3) along which dimensions the shared dataset scales, and (4) how sensitive the shared dataset is with respect to the input’s characteristics, i.e., node degree and connectivity in graph workloads. We observe significant variety in scaling behavior across workloads: some workloads feature a shared dataset that scales linearly with input size, whereas others feature sublinear scaling (following a \(\sqrt {2}\) or \(\sqrt [3]{2}\) relationship). We further demonstrate how the shared dataset affects the optimum last-level cache organization (memory-side versus SM-side) in multi-chip GPUs, as well as optimum memory page allocation and thread scheduling policy. Sensitivity analyses demonstrate the insights across the broad design space.