146 research outputs found
ECO-CHIP: Estimation of Carbon Footprint of Chiplet-based Architectures for Sustainable VLSI
Decades of progress in energy-efficient and low-power design have
successfully reduced the operational carbon footprint in the semiconductor
industry. However, this has led to an increase in embodied emissions,
encompassing carbon emissions arising from design, manufacturing, packaging,
and other infrastructural activities. While existing research has developed
tools to analyze embodied carbon at the computer architecture level for
traditional monolithic systems, these tools do not apply to near-mainstream
heterogeneous integration (HI) technologies. HI systems offer significant
potential for sustainable computing by minimizing carbon emissions through two
key strategies: ``reducing" computation by reusing pre-designed chiplet IP
blocks and adopting hierarchical approaches to system design. The reuse of
chiplets across multiple designs, even spanning multiple generations of
integrated circuits (ICs), can substantially reduce embodied carbon emissions
throughout the operational lifespan. This paper introduces a carbon analysis
tool specifically designed to assess the potential of HI systems in
facilitating greener VLSI system design and manufacturing approaches. The tool
takes into account scaling, chiplet and packaging yields, design complexity,
and even carbon overheads associated with advanced packaging techniques
employed in heterogeneous systems. Experimental results demonstrate that HI can
achieve a reduction of embodied carbon emissions up to 70\% compared to
traditional large monolithic systems. These findings suggest that HI can pave
the way for sustainable computing practices, contributing to a more
environmentally conscious semiconductor industry.Comment: Under review at HPCA2
Cross-layer design of thermally-aware 2.5D systems
Over the past decade, CMOS technology scaling has slowed down. To sustain the historic performance improvement predicted by Moore's Law, in the mid-2000s the computing industry moved to using manycore systems and exploiting parallelism. The on-chip power densities of manycore systems, however, continued to increase after the breakdown of Dennard's Scaling. This leads to the `dark silicon' problem, whereby not all cores can operate at the highest frequency or can be turned on simultaneously due to thermal constraints. As a result, we have not been able to take full advantage of the parallelism in manycore systems. One of the 'More than Moore' approaches that is being explored to address this problem is integration of diverse functional components onto a substrate using 2.5D integration technology. 2.5D integration provides opportunities to exploit chiplet placement flexibility to address the dark silicon problem and mitigate the thermal stress of today's high-performance systems. These opportunities can be leveraged to improve the overall performance of the manycore heterogeneous computing systems.
Broadly, this thesis aims at designing thermally-aware 2.5D systems. More specifically, to address the dark silicon problem of manycore systems, we first propose a single-layer thermally-aware chiplet organization methodology for homogeneous 2.5D systems. The key idea is to strategically insert spacing between the chiplets of a 2.5D manycore system to lower the operating temperature, and thus reclaim dark silicon by allowing more active cores and/or higher operating frequency under a temperature threshold. We investigate manufacturing cost and thermal behavior of 2.5D systems, then formulate and solve an optimization problem that jointly maximizes performance and minimizes manufacturing cost. We then enhance our methodology by incorporating a cross-layer co-optimization approach. We jointly maximize performance and minimize manufacturing cost and operating temperature across logical, physical, and circuit layers. We propose a novel gas-station link design that enables pipelining in passive interposers. We then extend our thermally-aware optimization methodology for network routing and chiplet placement of heterogeneous 2.5D systems, which consist of central processing unit (CPU) chiplets, graphics processing unit (GPU) chiplets, accelerator chiplets, and/or memory stacks. We jointly minimize the total wirelength and the system temperature. Our enhanced methodology increases the thermal design power budget and thereby improves thermal-constraint performance of the system
Co-Package Technology Platform for Low-Power and Low-Cost Data Centers
We report recent advances in photonic–electronic integration developed in the European research project L3MATRIX. The aim of the project was to demonstrate the basic building blocks of a co-packaged optical system. Two-dimensional silicon photonics arrays with 64 modulators were fabricated. Novel modulation schemes based on slow light modulation were developed to assist in achieving an efficient performance of the module. Integration of DFB laser sources within each cell in the matrix was demonstrated as well using wafer bonding between the InP and SOI wafers. Improved semiconductor quantum dot MBE growth, characterization and gain stack designs were developed. Packaging of these 2D photonic arrays in a chiplet configuration was demonstrated using a vertical integration approach in which the optical interconnect matrix was flip-chip assembled on top of a CMOS mimic chip with 2D vertical fiber coupling. The optical chiplet was further assembled on a substrate to facilitate integration with the multi-chip module of the co-packaged system with a switch surrounded by several such optical chiplets. We summarize the features of the L3MATRIX co-package technology platform and its holistic toolbox of technologies to address the next generation of computing challenges
Recommended from our members
Heterogeneous Integration on Silicon-Interconnect Fabric using fine-pitch interconnects (≤10 �m)
Today, the ever-growing data-bandwidth demand is pushing the boundaries of the traditional printed circuit board (PCB) based integration schemes. Moreover, with the apparent saturation of semiconductor scaling, commonly called Moore's law, system scaling warrants a paradigm shift in packaging technologies, assembly techniques, and integration methodologies. In this work, a superior alternative to PCBs called the Silicon-Interconnect Fabric (Si-IF) is investigated. The Si-IF is a silicon-based, package-less, fine-pitch, highly scalable, heterogeneous integration platform for wafer-scale systems. In this technology, unpackaged dielets are assembled on the Si-IF at small inter-dielet spacings (≤100 �m) using fine-pitch (≤10 �m) die-to-substrate interconnects. A novel assembly process using a solder-less direct metal-metal (gold-gold and copper-copper) thermal compression bonding was developed. Using this process, sub-10 �m pitch interconnects with a low specific contact resistance of ≤0.7 Ω-�m2 were successfully demonstrated. Because of the tightly packed Si-IF assembly, the communication links between the neighboring dies are short (≤500 �m) with low loss (≤2 dB), comparable to on-chip connections. Consequently, simple buffers can transfer data between dies using a Simple Universal Parallel intERface for chips (SuperCHIPS) at low latency (<30 ps), low energy per bit (≤0.03 pJ/b), and high data-rates (up to 10 Gbps/link), corresponding to an aggregate bandwidth up to 8 Tbps/mm. The benefits of the SuperCHIPS protocol were experimentally demonstrated to provide 5-90X higher data-bandwidth, 8-30X lower latency, and 5-40X lower energy per bit compared to existing integration schemes. This dissertation addresses the assembly technology and communication protocols of the Si-IF technology
Heterogeneous 2.5D integration on through silicon interposer
© 2015 AIP Publishing LLC. Driven by the need to reduce the power consumption of mobile devices, and servers/data centers, and yet continue to deliver improved performance and experience by the end consumer of digital data, the semiconductor industry is looking for new technologies for manufacturing integrated circuits (ICs). In this quest, power consumed in transferring data over copper interconnects is a sizeable portion that needs to be addressed now and continuing over the next few decades. 2.5D Through-Si-Interposer (TSI) is a strong candidate to deliver improved performance while consuming lower power than in previous generations of servers/data centers and mobile devices. These low-power/high-performance advantages are realized through achievement of high interconnect densities on the TSI (higher than ever seen on Printed Circuit Boards (PCBs) or organic substrates), and enabling heterogeneous integration on the TSI platform where individual ICs are assembled at close proximity
High Efficiency Polymer based Direct Multi-jet Impingement Cooling Solution for High Power Devices
Liquid jet impingement cooling is an efficient cooling technique where the
liquid coolant is directly ejected from nozzles on the chip backside resulting
in a high cooling efficiency due to the absence of the TIM and the lateral
temperature gradient. In literature, several Si-fabrication based impingement
coolers with nozzle diameters of a few distributed returns or combination of
micro-channels and impingement nozzles. The drawback of this Si processing of
the cooler is the high fabrication cost. Other fabrication methods for nozzle
diameters for ceramic and metal. Low cost fabrication methods, including
injection molding and 3D printing have been introduced for much larger nozzle
diameters (mm range) with larger cooler dimensions. These dimensions and
processes are however not compatible with the chip packaging process flow. This
PhD focuses on the modeling, design, fabrication and characterization of a
micro-scale liquid impingement cooler using advanced, yet cost efficient,
fabrication techniques. The main objectives are: (a) development of a modeling
methodology to optimize the cooler geometry; (b) exploring low cost fabrication
methods for the package level impingement jet cooler; (c) experimental thermal
and hydraulic characterization and analysis of the fabricated coolers; (d)
applying the direct impingement jet cooling solutions to different
applications
Time-bin entanglement at telecom wavelengths from a hybrid photonic integrated circuit
Mass-deployable implementations for quantum communication require compact,
reliable, and low-cost hardware solutions for photon generation, control and
analysis. We present a fiber-pigtailed hybrid photonic circuit comprising
nonlinear waveguides for photon-pair generation and a polymer interposer
reaching 68dB of pump suppression and photon separation with >25dB polarization
extinction ratio. The optical stability of the hybrid assembly enhances the
quality of the entanglement, and the efficient background suppression and
photon routing further reduce accidental coincidences. We thus achieve a
96(-8,+3)% concurrence and a 96(-5,+2)% fidelity to a Bell state. The generated
telecom-wavelength, time-bin entangled photon pairs are ideally suited for
distributing Bell pairs over fiber networks with low dispersion
- …