A DLL Based Test Solution for 3D ICs

Integrated circuits (ICs) are rapidly changing and vertical integration and packaging strategies have already become an important research topic. 2.5D and 3D IC integrations have obvious advantages over the conventional two dimensional IC implementations in performance, capacity, and power consumption. A passive Si interposer utilizing Through-Silicon via (TSV) technology is used for 2.5D IC integration. TSV is also the enabling technology for 3D IC integration. TSV manufacturing defects can affect the performance of stacked devices and reduce the yield. Manufacturing test methodologies for TSVs have to be developed to ensure fault-free devices. This thesis presents two test methods for TSVs in 2.5D and 3D ICs utilizing Delay-Locked Loop (DLL) modules. In the test method developed for TSVs in 2.5D ICs, a DLL is used to determine the propagation delay for fault detection. TSV faults in 3D ICs are detected through observation of the control voltage of a DLL. The proposed test methods present a robust performance against Process, supply Voltage and Temperature (PVT) variations due to the inherent feedback of DLLs. 3D full-wave simulations are performed to extract circuit level models for TSVs and fragments of an interposer wires using HFSS simulation tools. The extracted TSV models are then used to perform circuit level simulations using ADS tools from Agilent. Simulation results indicate that the proposed test solution for TSVs can detect manufacturing defects affecting the TSV propagation delay

TSV Equivalent Circuit Model using 3D Full-Wave Analysis

This work presents a study to build lumped models for fault-free and faulty Through Silicon Vias (TSVs). Three dimensional full-wave simulations are performed to extract equivalent circuit models. The effects of parametric and catastrophic faults due to pin-holes, voids and open circuits on the equivalent circuit models have been determined through 3D simulations. The extracted TSV models are then used to conduct delay tests to determine the required measurement resolution to detect TSV defects. It is shown that the substrate conductivity has a considerable effect on TSV fault characterization. It is also shown that, regardless of the substrate type, even a relatively large void does not alter the TSV resistance or its parasitic capacitance noticeably at 1GHz solution frequency. An on-chip test solution for TSV parametric faults requires a dedicated high resolution measurement circuit due to the minor variations of TSV circuit model parameters