Brandon Noia

Pre-bond probing of TSVs in 3D stacked ICs

Through-Silicon Via (TSV)-based 3D stacked ICs (SICs) are becoming increasingly important in the semiconductor industry, yet pre-bond testing of TSVs continues to be difficult with current technologies. In this paper, we present a test and DFT method for pre-bond testing of TSVs using probe technology. We describe the on-die test architecture and probe technique needed for TSV testing, in which individual probe needles make contact with multiple TSVs at a time. We also describe methods for capacitance and resistance measurements, as well as stuck-at and leakage tests. Simulation results using HSPICE are presented for a TSV network. We demonstrate that we can achieve high resolution in these measurements, and therefore high accuracy in defect detection when we target one or multiple TSVs at a time. We also show that the test outcome is reliable even in the presence of process variations or multiple defective TSVs.

Optimization methods for post-bond die-internal/external testing in 3D stacked ICs

Testing of three-dimensional (3D) stacked ICs (SICs) is starting to receive considerable attention in the semiconductor industry. Since the die-stacking steps of thinning, alignment, and bonding can introduce defects, there is a need to test multiple subsequent partial stacks during 3D assembly. We address the problem of test-architecture optimization for 3D stacked ICs to minimize overall test time when either the complete stack only, or the complete stack and multiple partial stacks, need to be tested. We show that optimal test-architecture solutions and test schedules for multiple test insertions are different from their counterparts for a single final stack test. In addition, we present optimization techniques for the testing of TSVs and die-external logic in combination with the dies in the stack.

Test-wrapper optimization for embedded cores in TSV-based three-dimensional SOCs

System-on-chip (SOC) designs comprised of a number of embedded cores are widespread in todays integrated circuits. Embedded core-based design is likely to be equally popular for three-dimensional integrated circuits (3D ICs), the manufacture of which has become feasible in recent years. 3D integration offers a number of advantages over traditional two-dimensional (2D) technologies, such as the reduction in the average interconnect length, higher performance, lower interconnect power consumption, and smaller IC footprint. Despite recent advances in 3D fabrication and design methods, no attempt has been made thus far to design a 1500-style test wrapper for an embedded core that spans multiple layers in a 3D SOC. This paper addresses wrapper optimization in 3D ICs based on through-silicon vias (TSVs) for vertical interconnects. Our objective is to minimize the scan-test time for a core under constraints on the total number of TSVs available for testing. We present two polynomial-time heuristic solutions. Simulation results are presented for embedded cores from the ITC 2002 SOC test benchmarks.

Identification of Defective TSVs in Pre-Bond Testing of 3D ICs

Pre-bond testing of TSVs has been identified as a major challenge for yield assurance in 3D ICs. We present a defective-TSV localization technique based on pre-bond probing of a network of TSVs. We describe an efficient algorithm for designing parallel TSV test sessions such that test time is reduced and a given number of faulty TSVs within the TSV network can be uniquely identified. Optimization results for various networks of TSVs highlight significant reduction in test time using the proposed method.

Optimization Methods for Post-Bond Testing of 3D Stacked ICs

Testing of three-dimensional (3D) stacked ICs (SICs) is starting to receive considerable attention in the semiconductor industry. Since the die-stacking steps of thinning, alignment, and bonding can introduce defects, there may be a need to test multiple subsequent partial stacks during 3D assembly. We address the problem of test-architecture optimization for 3D stacked ICs to minimize overall test time when either the complete stack only, or the complete stack and multiple partial stacks, need to be tested. A general solution to this problem provides several options for 3D stack testing in a unified framework. We show that optimal test-architecture solutions and test schedules for multiple test insertions are different from their counterparts for a single final stack test. In addition, we present optimization techniques for the testing of TSVs and die-external logic in combination with the dies in the stack.

Scan test of die logic in 3D ICs using TSV probing

Pre-bond testing of TSVs and die logic is a significant challenge and a potential roadblock for 3D integration. BIST solutions introduce considerable die area overhead. Oversized probe pads on TSVs to provide pre-bond test access limit both test bandwidth and TSV density. This paper presents a solution to these problems, allowing a probe card to contact TSVs without the need for probe pads, enabling both TSV and pre-bond scan test. Two possible pre-bond scan test configurations are shown - they provide varying degrees of test parallelism. HSPICE simulations are performed on a logic-on-logic 3D benchmark. Results show that the ratio of the number of probe needles available for test access to the number of pre-bond scan chains determines which pre-bond scan configuration results in the shortest test time. Maximum pre-bond scan-in and scan-out shift-clock speeds are determined for dies in a benchmark 3D design. These clock speeds show that pre-bond scan test can be performed quickly, at a speed that is comparable to scan testing of packaged dies. The maximum clock speed can also be tuned by changing the drive strength of the probe and on-die drivers of the TSV network. Estimates are also provided for peak and average power consumption during pre-bond scan test. On-die area overhead for the proposed method is estimated to be between 1.0% and 2.2% for three dies in the 3D stack.

Pre-Bond Probing of Through-Silicon Vias in 3-D Stacked ICs

Through-silicon via (TSV)-based 3-D stacked ICs are becoming increasingly important in the semiconductor industry, yet pre-bond testing of TSVs continues to be difficult with current technologies. In this paper, we present a test and discrete Fourier transform method for pre-bond testing of TSVs using probe technology. We describe the on-die test architecture and probe technique needed for TSV testing, in which individual probe needles make contact with multiple TSVs at a time. We also describe methods for capacitance and resistance measurements, as well as stuck-at and leakage tests. Simulation results using HSPICE are presented for a TSV network. We demonstrate that we can achieve high resolution in these measurements, and therefore high accuracy in defect detection when we target one or multiple TSVs at a time. We also show that the test outcome is reliable even in the presence of process variations or multiple defective TSVs.

Design-for-Test and Test Optimization Techniques for TSV-based 3D Stacked ICs

This book describes innovative techniques to address the testing needs of 3D stacked integrated circuits (ICs) that utilize through-silicon-vias (TSVs) as vertical interconnects. The authors identify the key challenges facing 3D IC testing and present results that have emerged from cutting-edge research in this domain. Coverage includes topics ranging from die-level wrappers, self-test circuits, and TSV probing to test-architecture design, test scheduling, and optimization. Readers will benefit from an in-depth look at test-technology solutions that are needed to make 3D ICs a reality and commercially viable.

Scan Test of Die Logic in 3-D ICs Using TSV Probing

Prebond testing of through-silicon-vias (TSVs) and die logic is a significant challenge and a potential roadblock for 3-D integration. Built-in self-test solutions introduce considerable die area overhead. Oversized probe pads on TSVs to provide prebond test access limit both test bandwidth and TSV density. This paper presents a solution to these problems, allowing a probe card to contact TSVs without the need for probe pads, enabling both TSV and prebond scan test. Several possible prebond scan test configurations are shown-they provide varying degrees of test parallelism under design constraints. HSPICE simulations are performed on two logic-on-logic 3-D benchmarks. Results show that the ratio of the number of probe needles available for test access to the number of prebond scan chains determines which prebond scan configuration results in the shortest test time. Maximum prebond scan-in and scan-out shift-clock speeds are determined for dies in a benchmark 3-D design as a function of driver strength and transmission gate width. These clock speeds show that prebond scan test can be performed at a speed that is comparable with scan testing of packaged dies. The maximum clock speed can also be tuned by changing the drive strength of the probe and on-die drivers of the TSV network. Estimates are also provided for peak and average power consumption during prebond scan test for both a high-power pattern per scan chain and an average power pattern per scan chain. On-die area overhead for the proposed method is estimated to be between 1.0% and 2.9% per die for two 3-D benchmarks.

Test and Design-for-Testability Solutions for 3D Integrated Circuits

Despite the promise and benefits offered by 3D integration, testing remains a major obstacle that hinders its widespread adoption. Test techniques and design-for-testability (DfT) solutions for 3D ICs are now being studied in the research community, and experts in industry have identified a number of hard problems related to the lack of probe access for wafers, test access in stacked dies, yield enhancement, and new defects arising from unique processing steps. We describe a number of testing and DfT challenges, and present some of the solutions being advocated for these challenges. Techniques highlighted in this paper include: (i) pre-bond testing of TSVs and die logic, including probing and non-invasive test using DfT; (ii) post-bond testing and DfT innovations related to the optimization of die wrappers, test scheduling, and access to dies and inter-die interconnects; (iii) interconnect testing in interposer-based 2.5D ICs; (iv) fault diagnosis and TSV repair; (v) cost modeling and test-flow selection.