Chunghyun Ryu

Development and Evaluation of 3-D SiP with Vertically Interconnected Through Silicon Vias (TSV)

For high density and performance of microelectronic devices, the 3-D system in package (SiP) has been considered as a superb microelectronic packaging system. The development and evaluation of stacked chip type 3-D SiP with vertically interconnected TSV are reported. The process includes; 55 mum-diameter via holes by reactive ion etching (RIE), SiO2 dielectric layer by thermal oxidation, Ta and Cu seed layers by ionized metal plasma (IMP), Cu via filling by electroplating, Cu/Sn bump for multi-chip stacking and finally chip-to-PCB bonding with Sn-3.0Ag-0.5Cu solder and ENIG pad. A prototype 3-D SiP with 10 stacked chips was successfully fabricated. High frequency electrical model of the TSV was proposed and the model parameters were extracted from the measured S-parameters. The proposed model was verified by TDR/TDT (time domain reflectometry/time domain transmission) and eye-diagram measurement. And then, contact resistances of Cu via and bump joint were discussed.

Electrical characterization of trough silicon via (TSV) depending on structural and material parameters based on 3D full wave simulation

In this paper, we show the electrical characteristics of TSV (through silicon via) depending on structural parameters such as TSV pitch, TSV height, TSV size and thickness of SiO2 for DC leakage blocking between TSV and silicon substrate, and material parameter of silicon substrate such as silicon resistivity in case of single silicon substrate. And we also show X-talk characteristics of two TSVs depending on distance of two signal TSVs and different locations of two signal TSVs and two ground TSVs in array type arrangement of TSV. Additionally, we show the electrical characteristics of TSV depending on number of stacked TSVs. All electrical characterizations on this paper are obtained using commercial 3-D full wave simulator and spice type circuit simulator such as HFSS of Ansoft Corporation and ADS of Agilent Corporation, respectively.

High Frequency Electrical Model of Through Wafer Via for 3-D Stacked Chip Packaging

In this paper, we propose an equivalent circuit model of through wafer via which has height of 90 mum and diameter of 75 mum. The equivalent circuit model composed of RLCG components is developed based on the physical configuration of through wafer via. Then, the parameter values of the equivalent circuit model are fitted to the measured s-parameters up to 20GHz by parameter optimization method. The proposed model shows through wafer via is dominantly characterized by the capacitance of thin oxide around the via and resistive characteristic of lossy silicon substrate. From simulated TDR/TDT and eye-diagram waveforms of the proposed equivalent circuit model, it is found that parasitic effects of the via cause slow rising time of a signal during transmission of the signal to the through wafer via. However, unlike to the most cases, the slow rising time of through wafer via will not degrade signal integrity severely. At last, we show the effect of dimension of through wafer via on performance of signal transmission using 3D full wave simulation

High frequency electrical circuit model of chip-to-chip vertical via interconnection for 3-D chip stacking package

In this paper, we firstly propose the high frequency equivalent circuit model of the chip-to-chip vertical via based on its physical configuration. The model parameters are extracted from the measurement of S-parameters using a vector network analyzer up to 20GHz frequency range. The proposed circuit model is verified experimentally in frequency and time domains. Furthermore, the high frequency characteristics of the chip-to-chip vertical via are investigated.

Modeling and Measurement of Interlevel Electromagnetic Coupling and Fringing Effect in a Hierarchical Power Distribution Network Using Segmentation Method With Resonant Cavity Model

A hierarchical power distribution network (PDN) consists of chip, package, and printed circuit board (PCB) level PDNs, as well as various structures such as via, ball, and wire bond interconnections, which connect the different level PDNs. When estimating the simultaneous switching noise (SSN) generation and evaluating PDN designs, PDN impedance calculation is an efficient criterion. In this paper, we introduce two new kinds of modeling approaches that are exceptionally suited to improving the accuracy of the PDN impedance estimation, especially for hierarchical PDN. First, we propose a modeling procedure to add an interlevel electromagnetic coupling effect between PDNs of different levels, based on the resonant cavity model and segmentation method. In order to effectively consider the interlevel electromagnetic coupling effect, we introduce a new concept of interlevel PDN, which is, for example, composed of a metal plate in the package-level PDN and a metal plate in the PCB-level PDN. Next, we present a modeling procedure to include the fringing field effect at the edge of small-size PDN structure, which causes a considerable shift of cavity resonance frequencies in the PDN impedance profile. In order to verify the proposed modeling approaches, we have fabricated a series of test vehicles by combining two package-level PDN designs with a PCB-level PDN design. Finally, we have successfully validated the proposed modeling approaches with a series of frequency-domain measurements in a frequency range up to 5 GHz.

Suppression of Power/Ground Inductive Impedance and Simultaneous Switching Noise Using Silicon Through-Via in a 3-D Stacked Chip Package

We have thoroughly investigated the advantages of a silicon through-via (STV) interconnection in decreasing the inductive impedance of a power distribution network (PDN) and suppressing simultaneous switching noise (SSN) in a 3-D stacked chip package. A double-stacked chip package with STV interconnections was fabricated and measured together with a similar double-stacked chip package with conventional bonding-wire interconnections. We successfully demonstrated that significant reduction of the inductive PDN impedance, from 1.66 nH to 0.79 nH, can be achieved by replacing the conventional bonding wires in the multiple-stacked chip package by STV interconnections. Furthermore, we have shown that the STV interconnections can considerably reduce high-frequency SSN, by more than 80%, compared to the conventional bonding-wire interconnections.

Chip-package hybrid clock distribution network and DLL for low jitter clock delivery

This paper presents a chip-package hybrid clock distribution network and delay-locked loop (DLL) with which to achieve extremely low jitter clock delivery. The proposed hybrid clock distribution network and DLL provide digital noise-free and low-jitter clock signals by utilizing lossless package layer interconnections instead of lossy on-chip global wires with cascaded repeaters. The lossless package layer interconnections become high-frequency waveguides and provide a repeater-free clock distribution network; thus, the clock signal becomes free of on-chip power supply noise. The proposed chip-package hybrid clock scheme has demonstrated a 78-ps peak-to-peak jitter at 500 MHz under a 240-mV on-chip simultaneous switching noise condition versus a conventional clock scheme, which produced a 172-ps peak-to-peak jitter under the same condition. Moreover, the proposed scheme has demonstrated an 80-ps long-term jitter with a 300-mV DC voltage drop test condition, contrasted with the 380-ps long-term jitter of a conventional clock scheme. Finally, the proposed hybrid clock scheme has a confirmed delay of 1.47 ns versus a conventional clock scheme delay of 2.85 ns.

Wideband low power distribution network impedance of high chip density package using 3-D stacked through silicon vias

In this paper, we show the advantages of 3D stacked through silicon via (TSV) in high chip density package in aspect of wideband and low power distribution network (PDN) impedance. We selected large size (80 mum) and large pitch (200 mum) TSV with thick silicon substrate (Si, 80 mum, aspect ratio =1) for on-chip PDN, and compared two total PDN impedances of a PDN with TSVs and a PDN with wire-bondings depending on number of stacked chips from 2 to 10 on a single package. PDN impedance with TSVs includes total capacitance and inductance of TSV and 20 mm times 20 mm package substrate. PDN impedance with wire-bondings shows total capacitance and inductance of wire-bondings and same size package substrate. PDN impedance with TSVs has lower levels with wide bandwidth from 10 MHz to 5 GHz except serial resonance frequency range of the package substrate around 350 MHz. In low frequency range from 10 MHz to 350 MHz, total capacitance of a PDN with TSVs is larger than that of a PDN with wire-bonding because of 0.1 mum thickness silicon oxide (Si02) for blocking DC leakage from TSV to Si substrate. Over 350 MHz, total inductance of a PDN with TSVs is smaller than that of a PDN with wire-bonding because TSV is the smallest electrical path from top surface of stacked chips to the package PDN. The effectiveness of lowering total PDN impedance is better when the number of stacked chips is growing because total length of TSVs is linearly increased with factor 1 while total length of wire-bonding is done with factor radic(2).

A chip-package hybrid DLL loop and clock distribution network for low-jitter clock delivery

A chip-package hybrid DLL and clock distribution network provides low-jitter clock signals by utilizing separate supply connections and lossless package layer interconnections instead of on-chip global wires. The hybrid scheme has 78ps/sub co/ jitter and under 240mV digital noise at 500MHz, while a conventional scheme has a 172ps/sub p-p/ jitter under the same conditions.

A Three-Dimensional Stacked-Chip Star-Wiring Interconnection for a Digital Noise-Free and Low-Jitter I/O Clock Distribution Network

Cascaded repeaters are indispensable circuit elements in conventional on-chip clock distribution networks due to heavy loss characteristics of on-chip global interconnections. However, cascaded repeaters cause significant jitter and skew problems in clock distribution networks when they are affected by power supply switching noise generated by digital logic blocks located on the same die. In this letter, we present a new three-dimensional (3-D) stacked-chip star-wiring interconnection scheme to make a clock distribution network free from both on-chip and package-level power supply noise coupling. The proposed clock distribution scheme provides an extremely low-jitter and low-skew clock signal by replacing the cascaded repeaters with lossless star-wiring interconnections on a 3-D stacked-chip package. We have demonstrated a 500-MHz input/output (I/O) clock delivery with 34-ps peak-to-peak jitter and a skew of 11ps, while a conventional I/O clock scheme exhibited a 146-ps peak-to-peak jitter and a 177-ps skew in the same power supply noise environment