Fast 3D Integrated Circuit Placement Methodology using Merging Technique

In the recent years the advancement in the field of microelectronics integrated circuit (IC) design technologies proved to be a boon for design and development of various advanced systems in-terms of its reduction in form factor, low power, high speed and with increased capacity to incorporate more designs. These systems provide phenomenal advantage for armoured fighting vehicle (AFV) design to develop miniaturised low power, high performance sub-systems. One such emerging high-end technology to be used to develop systems with high capabilities for AFVs is discussed in this paper. Three dimensional IC design is one of the emerging field used to develop high density heterogeneous systems in a reduced form factor. A novel grouping based partitioning and merge based placement (GPMP) methodology for 3D ICs to reduce through silicon vias (TSVs) count and placement time is proposed. Unlike state-of-the-art techniques, the proposed methodology does not suffer from initial overlap of cells during intra-layer placement which reduces the placement time. Connectivity based grouping and partitioning ensures less number of TSVs and merge based placement further reduces intra layer wire-length. The proposed GPMP methodology has been extensively against the IBMPLACE database and performance has been compared with the latest techniques resulting in 12 per cent improvement in wire-length, 13 per cent reduction in TSV and 1.1x improvement in placement time

Through-silicon-via-aware prediction and physical design for multi-granularity 3D integrated circuits

The main objective of this research is to predict the wirelength, area, delay, and power of multi-granularity three-dimensional integrated circuits (3D ICs), to develop physical design methodologies and algorithms for the design of multi-granularity 3D ICs, and to investigate the impact of through-silicon vias (TSVs) on the quality of 3D ICs. This dissertation supports these objectives by addressing six research topics. The first pertains to analytical models that predict the interconnects of multi-granularity 3D ICs, and the second focuses on the development of analytical models of the capacitive coupling of TSVs. The third and the fourth topics present design methodologies and algorithms for the design of gate- and block-level 3D ICs, and the fifth topic pertains to the impact of TSVs on the quality of 3D ICs. The final topic addresses topography variation in 3D ICs. The first section of this dissertation presents TSV-aware interconnect prediction models for multi-granularity 3D ICs. As previous interconnect prediction models for 3D ICs did not take TSV area into account, they were not capable of predicting many important characteristics of 3D ICs related to TSVs. This section will present several previous interconnect prediction models that have been improved so that the area occupied by TSVs is taken into account. The new models show numerous important predictions such as the existence of the number of TSVs minimizing wirelength. The second section presents fast estimation of capacitive coupling of TSVs and wires. Since TSV-to-TSV and TSV-to-wire coupling capacitance is dependent on their relative locations, fast estimation of the coupling capacitance of a TSV is essential for the timing optimization of 3D ICs. Simulation results show that the analytical models presented in this section are sufficiently accurate for use at various design steps that require the computation of TSV capacitance. The third and fourth sections present design methodologies and algorithms for gate- and block-level 3D ICs. One of the biggest differences in the design of 2D and 3D ICs is that the latter requires TSV insertion. Since no widely-accepted design methodology designates when, where, and how TSVs are inserted, this work develops and presents several design methodologies for gate- and block-level 3D ICs and physical design algorithms supporting them. Simulation results based on GDSII-level layouts validate the design methodologies and present evidence of their effectiveness. The fifth section explores the impact of TSVs on the quality of 3D ICs. As TSVs become smaller, devices are shrinking, too. Since the relative size of TSVs and devices is more critical to the quality of 3D ICs than the absolute size of TSVs and devices, TSVs and devices should be taken into account in the study of the impact of TSVs on the quality of 3D ICs. In this section, current and future TSVs and devices are combined to produce 3D IC layouts and the impact of TSVs on the quality of 3D ICs is investigated. The final section investigates topography variation in 3D ICs. Since landing pads fabricated in the bottommost metal layer are attached to TSVs, they are larger than TSVs, so they could result in serious topography variation. Therefore, topography variation, especially in the bottommost metal layer, is investigated and two layout optimization techniques are applied to a global placement algorithm that minimizes the topography variation of the bottommost metal layer of 3D ICs.PhDCommittee Chair: Lim, Sung Kyu; Committee Member: Bakir, Muhannad; Committee Member: Kim, Hyesoon; Committee Member: Lee, Hsien-Hsin Sean; Committee Member: Mukhopadhyay, Saiba

Placement for fast and reliable through-silicon-via (TSV) based 3D-IC layouts

The objective of this research is to explore the feasibility of addressing the major performance and reliability problems or issues, such as wirelength, stress-induced carrier mobility variation, temperature, and quality trade-offs, found in three-dimensional integrated circuits (3D ICs) that use through-silicon vias (TSVs) at placement stage. Four main works that support this goal are included. In the first work, wirelength of TSV-based 3D ICs is the main focus. In the second work, stress-induced carrier mobility variation in TSV-based 3D ICs is examined. In the third work, temperature inside TSV-based 3D ICs is investigated. In the final work, the quality trade-offs of TSV-based 3D-IC designs are explored. In the first work, a force-directed, 3D, and gate-level placement algorithm that efficiently handles TSVs is developed. The experiments based on synthesized benchmarks indicate that the developed algorithm helps generate GDSII layouts of 3D-IC designs that are optimized in terms of wirelength. In addition, the impact of TSVs on other physical aspects of 3D-IC designs is also studied by analyzing the GDSII layouts. In the second work, the model for carrier mobility variation caused by TSV and STI stresses is developed as well as the timing analysis flow considering the stresses. The impact of TSV and STI stresses on carrier mobility variation and performance of 3D ICs is studied. Furthermore, a TSV-stress-driven, force-directed, and 3D placement algorithm is developed. It exploits carrier mobility variation, caused by stress around TSVs after fabrication, to improve the timing and area objectives during placement. In addition, the impact of keep-out zone (KOZ) around TSVs on stress, carrier mobility variation, area, wirelength, and performance of 3D ICs is studied. In the third work, two temperature-aware global placement algorithms are developed. They exploit die-to-die thermal coupling in 3D ICs to improve temperature during placement. In addition, a framework used to evaluate the results from temperature-aware global placements is developed. The main component of the framework is a GDSII-level thermal analysis that considers all structures inside a TSV-based 3D IC while computing temperature. The developed placers are compared with several state-of-the-art placers published in recent literature. The experimental results indicate that the developed algorithms help improve the temperature of 3D ICs effectively. In the final work, three block-level design styles for TSV-based die-to-wafer bonded 3D ICs are discussed. Several 3D-IC layouts in the three styles are manually designed. The main difference among these layouts is the position of TSVs. Finally, the area, wirelength, timing, power, temperature, and mechanical stress of all layouts are compared to explore the trade-offs of layout quality.PhDCommittee Chair: Lim, Sung Kyu; Committee Member: Bakir, Muhannad; Committee Member: Kim, Hyesoon; Committee Member: Mukhopadhyay, Saibal; Committee Member: Swaminathan, Madhava

Electro-Thermal Codesign in Liquid Cooled 3D ICs: Pushing the Power-Performance Limits

The performance improvement of today's computer systems is usually accompanied by increased chip power consumption and system temperature. Modern CPUs dissipate an average of 70-100W power while spatial and temporal power variations result in hotspots with even higher power density (up to 300W/cm^2). The coming years will continue to witness a significant increase in CPU power dissipation due to advanced multi-core architectures and 3D integration technologies. Nowadays the problems of increased chip power density, leakage power and system temperatures have become major obstacles for further improvement in chip performance. The conventional air cooling based heat sink has been proved to be insufficient for three dimensional integrated circuits (3D-ICs). Hence better cooling solutions are necessary. Micro-fluidic cooling, which integrates micro-channel heat sinks into silicon substrates of the chip and uses liquid flow to remove heat inside the chip, is an effective active cooling scheme for 3D-ICs. While the micro-fluidic cooling provides excellent cooling to 3D-ICs, the associated overhead (cooling power consumed by the pump to inject the coolant through micro-channels) is significant. Moreover, the 3D-IC structure also imposes constraints on micro-channel locations (basically resource conflict with through-silicon-vias TSVs or other structures). In this work, we investigate optimized micro-channel configurations that address the aforementioned considerations. We develop three micro-channel structures (hotspot optimized cooling configuration, bended micro-channel and hybrid cooling network) that can provide sufficient cooling to 3D-IC with minimum cooling power overhead, while at the same time, compatible with the existing electrical structure such as TSVs. These configurations can achieve up to 70% cooling power savings compared with the configuration without any optimization. Based on these configurations, we then develop a micro-fluidic cooling based dynamic thermal management approach that maintains the chip temperature through controlling the fluid flow rate (pressure drop) through micro-channels. These cooling configurations are designed after the electrical parts, and therefore, compatible with the current standard IC design flow. Furthermore, the electrical, thermal, cooling and mechanical aspects of 3D-IC are interdependent. Hence the conventional design flow that designs the cooling configuration after electrical aspect is finished will result in inefficiencies. In order to overcome this problem, we then investigate electrical-thermal co-design methodology for 3D-ICs. Two co-design problems are explored: TSV assignment and micro-channel placement co-design, and gate sizing and fluidic cooling co-design. The experimental results show that the co-design enables a fundamental power-performance improvement over the conventional design flow which separates the electrical and cooling design. For example, the gate sizing and fluidic cooling co-design achieves 12% power savings under the same circuit timing constraint and 16% circuit speedup under the same power budget

TSV placement optimization for liquid cooled 3D-ICs with emerging NVMs

Three dimensional integrated circuits (3D-ICs) are a promising solution to the performance bottleneck in planar integrated circuits. One of the salient features of 3D-ICs is their ability to integrate heterogeneous technologies such as emerging non-volatile memories (NVMs) in a single chip. However, thermal management in 3D-ICs is a significant challenge, owing to the high heat flux (~ 250 W/cm2). Several research groups have focused either on run-time or design-time mechanisms to reduce the heat flux and did not consider 3D-ICs with heterogeneous stacks. The goal of this work is to achieve a balanced thermal gradient in 3D-ICs, while reducing the peak temperatures. In this research, placement algorithms for design-time optimization and choice of appropriate cooling mechanisms for run-time modulation of temperature are proposed. Specifically, an architectural framework which introduce weight-based simulated annealing (WSA) algorithm for thermal-aware placement of through silicon vias (TSVs) with inter-tier liquid cooling is proposed for design-time. In addition, integrating a dedicated stack of emerging NVMs such as RRAM, PCRAM and STTRAM, a run-time simulation framework is developed to analyze the thermal and performance impact of these NVMs in 3D-MPSoCs with inter-tier liquid cooling. Experimental results of WSA algorithm implemented on MCNC91 and GSRC benchmarks demonstrate up to 11 K reduction in the average temperature across the 3D-IC chip. In addition, power density arrangement in WSA improved the uniformity by 5%. Furthermore, simulation results of PARSEC benchmarks with NVM L2 cache demonstrates a temperature reduction of 12.5 K (RRAM) compared to SRAM in 3D-ICs. Especially, RRAM has proved to be thermally efficient replacement for SRAM with 34% lower energy delay product (EDP) and 9.7 K average temperature reduction

Thermal-Aware Test Schedule and TAM Co-Optimization for Three-Dimensional IC

[[abstract]]Testing is regarded as one of the most difficult challenges for three-dimensional integrated circuits (3D ICs). In this paper, we want to optimize the cost of TAM (test access mechanism) and the test time for 3D IC. We used both greedy and simulated annealing algorithms to solve this optimization problem. We compare the results of two assumptions: soft-die mode and hard-die mode. The former assumes that the DfT of dies cannot be changed, while the latter assumes that the DfT of dies can be adjusted. The results show that thermal-aware cooptimization is essential to decide the optimal TAM and test schedule. Blindly adding TAM cannot reduce the total test cost due to temperature constraints. Another conclusion is that soft-die mode is more effective than hard-die mode to reduce the total test cost for 3D IC.[[notice]]補正完畢[[booktype]]電子

Exploration and Design of Power-Efficient Networked Many-Core Systems

Multiprocessing is a promising solution to meet the requirements of near future applications. To get full benefit from parallel processing, a manycore system needs efficient, on-chip communication architecture. Networkon- Chip (NoC) is a general purpose communication concept that offers highthroughput, reduced power consumption, and keeps complexity in check by a regular composition of basic building blocks. This thesis presents power efficient communication approaches for networked many-core systems. We address a range of issues being important for designing power-efficient manycore systems at two different levels: the network-level and the router-level. From the network-level point of view, exploiting state-of-the-art concepts such as Globally Asynchronous Locally Synchronous (GALS), Voltage/ Frequency Island (VFI), and 3D Networks-on-Chip approaches may be a solution to the excessive power consumption demanded by today’s and future many-core systems. To this end, a low-cost 3D NoC architecture, based on high-speed GALS-based vertical channels, is proposed to mitigate high peak temperatures, power densities, and area footprints of vertical interconnects in 3D ICs. To further exploit the beneficial feature of a negligible inter-layer distance of 3D ICs, we propose a novel hybridization scheme for inter-layer communication. In addition, an efficient adaptive routing algorithm is presented which enables congestion-aware and reliable communication for the hybridized NoC architecture. An integrated monitoring and management platform on top of this architecture is also developed in order to implement more scalable power optimization techniques. From the router-level perspective, four design styles for implementing power-efficient reconfigurable interfaces in VFI-based NoC systems are proposed. To enhance the utilization of virtual channel buffers and to manage their power consumption, a partial virtual channel sharing method for NoC routers is devised and implemented. Extensive experiments with synthetic and real benchmarks show significant power savings and mitigated hotspots with similar performance compared to latest NoC architectures. The thesis concludes that careful codesigned elements from different network levels enable considerable power savings for many-core systems.Siirretty Doriast

Enabling Technologies for 3D ICs: TSV Modeling and Analysis

Through silicon via (TSV) based three-dimensional (3D) integrated circuit (IC) aims to stack and interconnect dies or wafers vertically. This emerging technology offers a promising near-term solution for further miniaturization and the performance improvement of electronic systems and follows a more than Moore strategy. Along with the need for low-cost and high-yield process technology, the successful application of TSV technology requires further optimization of the TSV electrical modeling and design. In the millimeter wave (mmW) frequency range, the root mean square (rms) height of the TSV sidewall roughness is comparable to the skin depth and hence becomes a critical factor for TSV modeling and analysis. The impact of TSV sidewall roughness on electrical performance, such as the loss and impedance alteration in the mmW frequency range, is examined and analyzed following the second order small perturbation method. Then, an accurate and efficient electrical model for TSVs has been proposed considering the TSV sidewall roughness effect, the skin effect, and the metal oxide semiconductor (MOS) effect. However, the emerging application of 3D integration involves an advanced bio-inspired computing system which is currently experiencing an explosion of interest. In neuromorphic computing, the high density membrane capacitor plays a key role in the synaptic signaling process, especially in a spike firing analog implementation of neurons. We proposed a novel 3D neuromorphic design architecture in which the redundant and dummy TSVs are reconfigured as membrane capacitors. This modification has been achieved by taking advantage of the metal insulator semiconductor (MIS) structure along the sidewall, strategically engineering the fixed oxide charges in depletion region surrounding the TSVs, and the addition of oxide layer around the bump without changing any process technology. Without increasing the circuit area, these reconfiguration of TSVs can result in substantial power consumption reduction and a significant boost to chip performance and efficiency. Also, depending on the availability of the TSVs, we proposed a novel CAD framework for TSV assignments based on the force-directed optimization and linear perturbation

Test Planning for 3D SICs using ILP

In this paper we propose a test planning scheme for corebased 3D stacked integrated circuits where the total test cost for wafer sort of each individual chip and the test cost of the complete stack at package test is minimized. We use an Integer Linear Programming (ILP) model to find the optimal test cost, which is given as the weighted sum of the test time and the test access mechanism (TAM). As ILP is time consuming, we use a scheme to bound the test time and the TAM such that the search space is reduced. The proposed bounding scheme and the ILP model were applied on several ITC’02 benchmarks and the results show that optimal solutions were obtained at low computation time