Spare Through Silicon Via Research Articles

Cluster-aware allocation of spare TSVs for enhanced reliability in 3D ICs

Three-dimensional Integrated-Circuits (3D ICs) based on Through-Silicon-Via (TSV) technology offer numerous advantages, including high density, enhanced bandwidth, and lower power consumption. However, the complex manufacturing process introduces various defects, posing a considerable challenge to the reliability of 3D integration using TSVs. To address this issue, the utilization of spare TSVs as a solution for enhancing yield and reliability is a viable approach. In this study, we present a high-performance repair solution that efficiently allocates spare TSVs while minimizing hardware costs, area, and delay overhead. We introduce a spare TSV allocation scheme that considers the white space constraint, effectively reducing the delay overhead caused by excessive wire lengths. Our proposed solution achieves a significantly higher repair rate for densely clustered TSV defects compared to existing approaches. Moreover, our method stands out by reducing control logic area overhead by 65% or more when compared to previous works. Additionally, it significantly reduces delay overhead compared to other TSV redundancy architectures.

A cost-effective repair scheme for clustered TSV defects in 3D ICs

The current industry trend favors TSV (Through-Silicon-Via) based 3D ICs (Three-dimensional Integrated-Circuits) due to their several benefits. However, the complex manufacturing process emanates defects in TSVs. At the same time, clustered nature of TSV defects increases the probability of multiple defective neighbors TSVs. Therefore, reliability is one of the significant issues in the industry adoption of 3D integration based on TSVs. The repair solution of employing spare TSVs is an acceptable solution to enhance reliability. However, this solution incurs a significant amount of overheads. This study presents a cost-effective repair architecture to address the clustered TSV defects by organizing the neighbor TSVs. The proposed scheme secures a high repair rate for densely clustered defects. Besides, the proposed scheme reduces the significant area overhead compared to the existing TSV redundancy architectures.

TSV-Cluster Defect Tolerance Using Tree-Based Redundancy for Yield Improvement of 3-D ICs

Through silicon via (TSV)-based 3-D integrated circuit (3-D IC) has several advantages like high density, high bandwidth, and low-power consumption. However, many defects in TSV are evolved during the fabrication and bonding process. In practice, faulty TSVs tend to be clustered. Employing spare TSVs (s-TSVs) is an acceptable method for repairing faulty TSVs. This article introduces a tree-based TSV repair framework to utilize hardware resources more efficiently for a higher repair rate. The proposed architecture partitions the s-TSVs for a different level of redundancy sharing. Experimental results show that the proposed design consumes 11.01 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area per signal TSV to achieve 99.99% yield for 0.05% failure rate. The proposed architecture also exhibits a higher repair rate of 73.33% for heavily clustered faults. Moreover, for the same number of functional and s-TSVs, the proposed approach reduces the delay overhead efficiently compared to the prior works.

Virtualization-Based Efficient TSV Repair for 3-D Integrated Circuits

Three-dimensional (3-D) integration offers a promising solution to the technology scaling barriers. Reliability of the 3-D Integrated Circuits (ICs) is highly dependent on the integrity of the underlying interconnect. Through Silicon Via (TSV) based 3-D ICs would suffer from low yield due to the faults in TSVs. In addition, TSVs introduce stress and noise in the substrate. Adding redundant TSVs for repairing the faulty ones has commonly been proposed to improve the yield of TSV-based 3-D ICs. The existing TSV repair approaches employ a number of spare TSVs in a group of signal TSVs. We propose a TSV virtualization based repair architecture which utilizes a single redundant TSV to repair multiple faulty TSVs. The proposed architecture relies on transmitting multiple bits through a single TSV using multi-level voltage quantization. It makes efficient use of the TSV redundancies in repairing the faulty TSVs. With less number of spare TSVs, the proposed architecture can reduce the area overhead by more than 70%. Reduction in the TSV count allows greater interconnect density and helps to mitigate the TSV-induced noise and stresses. Alternatively, for a similar number of spare TSVs, the proposed method can enhance the fault tolerance capability of the conventional approaches thus leading to an enhanced chip yield. The eye diagram simulations using an electrical model of the TSV show a reduction of less than 5% in noise margin when using a 16-level voltage quantization at a data rate of 5 Gbps which is typical for 3-D integration applications.

Defect Clustering-Aware Spare-TSV Allocation in 3-D ICs for Yield Enhancement

The manufacturing yield challenge of 3-D integrated circuit is one of the key obstacles in the industry adoption of 3-D integration based on through-silicon-vias (TSVs). The addition of spare TSVs to repair faulty functional TSVs (f-TSVs) is an effective method for yield and reliability enhancement, but this approach results in significant hardware cost and delay overhead. Most existing solutions are only suitable for a “dual-uniform” scenario in which both the placement and the defect probabilities of f-TSVs are assumed to be uniform. In this paper, we propose a design technique that is compatible with nonuniform TSV placement and it can repair faulty TSVs based on a realistic clustered defect-distribution model. The proposed solution is based on two consecutive stages, which utilize a greedy algorithm and an integer-linear-programming formulation, respectively. By considering the tradeoff between chip yield, hardware cost, and delay overhead, the proposed technique provides higher yield and reliability under a clustered defect distribution, and with minimum hardware cost and delay overhead, compared to the previous work.

Adaptive 3D-IC TSV Fault Tolerance Structure Generation

In 3-D integrated circuits (3D-ICs), through silicon via (TSV) is a critical technique in providing vertical connections. However, the yield is one of the key obstacles to adopt the TSV-based 3D-ICs technology in industry. Various fault-tolerance structures using spare TSVs to repair faulty functional TSVs have been proposed in literature for yield and reliability enhancement, but a valid structure cannot always be found due to the lack of effective generation methods for fault-tolerance structures. In this paper, we focus on the problem of adaptive fault-tolerance structure (AFTS) generation. Given the relations between functional TSVs and spare TSVs, we first calculate the maximum number of tolerant faults in each TSV group. Then we propose an integer linear programming-based model to construct the AFTS with minimal multiplexer delay overhead and hardware cost. We further develop a speed-up technique through an efficient min-cost-max-flow model. All the proposed methodologies are embedded in a top-down TSV planning framework to form functional TSV groups and generate AFTSs. Experimental results show that, compared with state-of-the-art, the number of spare TSVs used for fault tolerance can be effectively reduced.

VFI-Based Power Management to Enhance the Lifetime of High-Performance 3D NoCs

The emergence of 3D network-on-chip (NoC) has revolutionized the design of high-performance and energy-efficient manycore chips. However, the anticipated performance gain can be compromised due to the degradation and failure of vertical links (VLs). The Through-Silicon-Via (TSV)-enabled VLs may fail due to workload-induced stress; the failure of a VL can affect the neighboring VLs, thereby causing a cascade of failures and reducing the lifetime of the chip. To enhance the reliability of 3D NoC-enabled manycore chips, we propose to incorporate a voltage-frequency island (VFI)-based power management strategy that helps to reduce the energy consumption and hence, the workload-induced stress of the highly utilized VLs. The adopted power-management strategy relies on control decisions about the voltage/frequency (V/F) levels on VLs. We demonstrate that compared to the well-known spare TSV allocation and adaptive routing strategies, power management is more effective in enhancing the reliability of a 3D NoC. VFI-based power management improves the reliability of the 3D NoC by one order of magnitude compared to both adaptive routing and spare allocation while running popular SPLASH-2 and PARSEC benchmarks. The principal benefit of power management is that it is capable of reducing the operating temperature of the system, which in turn enhances the Mean-Time-To-Failure (MTTF) of the VLs and reliability of the overall 3D NoC.

Clustered Fault Tolerance TSV Planning for 3-D Integrated Circuits

In 3-D integrated circuits (3-D ICs), through silicon via (TSV) is a critical technique to provide vertical connections. However, the yield and reliability challenge of TSV in industry is one of key obstacles to adopt the 3-D ICs technology. Various fault-tolerance structures by using additional spare TSVs (s-TSVs) to repair faulty functional TSVs (f-TSVs) have been proposed in literature for yield and reliability enhancement. However, these structures are formed in standard cell placement stage where all the f-TSVs are already placed. In reality, since the s-TSVs can be only inserted into the whitespace, the quality of the generated repair solution is strongly dependent on the whitespace distribution. In this paper, we propose an efficient TSV planning and repair framework in floorplanning stage, which takes nonuniform TSV distribution and clustered TSV defect-distribution into account. The proposed framework mainly consists of four stages: 1) a whitespace redistribution algorithm that uses a probability-based strategy to make the whitespace distribution more reasonable for the f-TSV planning. Subsequently, a convex-cost flow-based model for f-TSV allocation considering the fault clustering; 2) a top-down globally partitioning combined with a bottom-up locally merging to partition f-TSVs into groups with minimum hardware cost; 3) the min-cost max-flow algorithm for s-TSV allocation with minimum wirelength overhead; and 4) an integer linear programming-based model to form a fault-tolerance structure with minimum multiplexer delay overhead. The experimental results demonstrate that the proposed repair framework can improve the yield with minimum hardware cost and multiplexer delay overhead.

Novel Spare TSV Deployment for 3-D ICs Considering Yield and Timing Constraints

In 3-D integrated circuits, through silicon via (TSV) is a critical enabling technique to provide vertical connections. However, it may suffer from many reliability issues such as undercut, misalignment, or random open defects. Various fault-tolerance mechanisms have been proposed in literature to improve yield, at the cost of significant area overhead. In this paper, we focus on the structure that uses one spare TSV for a group of original TSVs, and study the optimal assignment of spare TSVs under yield and timing constraints to minimize the total area overhead. We show that such problem can be modeled as a constrained graph decomposition problem. Two efficient heuristics are further developed to address this problem. Experimental results show that under the same yield and timing constraints, our heuristic can reduce the area overhead induced by the fault-tolerance mechanisms by up to 61%, compared with a seemingly more intuitive nearest-neighbor-based heuristic.

Dynamic Self-Repair Architectures for Defective Through-silicon Vias

Three-dimensional integration technology results in area savings, platform power savings, and an increase in performance. Through-silicon via (TSV) assembly and manufacturing processes can potentially introduce defects. This may result in increases in manufacturing and test costs and will cause a yield problem. To improve the yield, spare TSVs can be included to repair defective TSVs. This paper proposes a new built-in self-test feature to identify defective TSV channels. For defective TSVs, this paper also introduces dynamic self-repair architectures using code-based and hardware-mapping based repair.

Virtualized and fault-tolerant inter-layer-links for 3D-ICs

Through Silicon Via (TSV) is the state-of-the-art vertical interconnect technology in three dimensional Integrated Circuits (3D-ICs). TSVs offer short wire length with low capacitive load and, hence, fast connections between two or more chip layers. On the other hand, TSVs consume a relative large amount of chip area and are error prone during manufacturing resulting in a dramatic yield drop for large TSV counts. Because of their short wire length, TSVs can be clocked much higher than conventional intra-layer links. To efficiently utilize the vertical bandwidth of TSVs, this paper proposes multiplexing several virtual links with dynamically allocated bit rates for guaranteed service connections via a shared TSV-Hub-Array. Virtual links can be state-of-the-art interconnects like busses, crossbars or 2D-NoC links. The TSV-Hub allows migration of traditional 2D interconnects towards the 3D stack while benefiting from a reduced TSV count and reuse of existing IP blocks and interconnection schemes. Furthermore, the TSV-Hub approach is also advantageous under interconnect resilience considerations. An incorporated switchbox enables dynamic protection switching for several faulty TSVs. Moreover, it can even cope with situations when more than the number of spare TSVs becomes defective. By means of a case study with two independent AXI interconnects, we could show an area reduction in the range of at least 10% for a TSV size of 10μm and conservatively estimated the reliability improvement by one order of magnitude in comparison to a direct link interconnection.