Browsing by Author "Chen, Hsiao-Yun"

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A Low-Overhead Interference Canceller for High-Mobility STBC-OFDM Systems
(2013-10-01)
Chen, Hsiao-Yun
;
Chang, Wei-Kai
;
Jou, Shyh-Jye
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper proposes a low-overhead space-time block code (STBC) interference canceller for high-mobility STBC-orthogonal frequency division multiplexing (STBC-OFDM) systems. The proposed STBC interference canceller combined with the two-stage channel estimator can be applied to wireless metropolitan area network (WMAN), like IEEE 802.16e system. At the vehicle speeds of 240 km/hr for 16 quadrature amplitude modulation (16 QAM), the bit error rate (BER) can be improved about 10 times of that just using the two-stage channel estimator. The proposed design is implemented in 90 nm CMOS technology. The gate count is 109.3 K, and the power dissipation is 1.45 mW at 83.3 MHz operation frequency with 1 V power supply. However, up to 61% hardware can be reused from the existed two-stage channel estimator design. After reusing, the proposed STBC interference canceller requires only 42.2 K gates, which is 4.9% overhead of the two-stage channel estimator.
A Robust Channel Estimator for High-Mobility STBC-OFDM Systems
(2010-04-01)
Chen, Hsiao-Yun
;
Ku, Meng-Lin
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Jou, Shyh-Jye
;
Huang, Chia-Chi
;
電機工程學系
In this paper, a robust channel estimator for high-mobility space-time block code-orthogonal frequency division multiplexing (STBC-OFDM) systems is proposed and applied in IEEE 802.16e systems. A high-performance two-stage channel estimation method is adopted. The proposed architecture reduces computational complexity effectively and improves 85.2% of the hardware implementation. The performances of the proposed design have been demonstrated through the simulation of an STBC-OFDM system with two transmit antennas and one receive antenna. At the vehicle speed of 120 and 240 km/hr for quadrature phase shift keying (QPSK) modulation, the proposed design can achieve the bit-error rate (BER) of about 10(-4) and 10(-3) without using channel coding. Moreover, it has significant performance improvement as compared with interpolation-based channel estimation methods. The proposed channel estimator implemented in 90 nm CMOS technology can support up to 29.03 Mbps (uncoded) downlink data transmission. The design only requires 859.6 K gates and dissipates 43.71 mW at 83.3 MHz operating frequency with 1 V power supply.
DC-balance low-jitter transmission code for 4-PAM-signaling
(2006-09-01)
Chen, Hsiao-Yun
;
Lin, Chih-Hsien
;
Jou, Shyh-Jye
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This investigation proposes a novel dc-balanced low-jitter transmission code, a 4-PAM symmetric code, for a 4-PAM signaling system. The 4-PAM symmetric code preserves all of the useful characteristics of the 8B/10B code such as dc-balanced serial data and guaranteed transitions in the symbol stream for clock recovery. Moreover, the proposed method decreases the jitter of the timing transition of the data in the receiver and consumes half of the data bandwidth, because it transmits in 4-PAM. The design results using the UMC 0.18-mu m process demonstrate that the new transmission code can decrease the jitter of the transition point by +/- 25% of the transition region. The operation speed of the encoder/decoder for the 4-PAM symmetric code is 819 MHz with 16-b inputs (13.1 Gb/s) and 704 MHz with 16-b outputs (11.3 Gb/s).
Effect of polyethylene glycol additives on pulse electroplating of SnAg solder
(2008-02-01)
Chen, Hsiao-Yun
;
Chen, Chih
;
Wu, Pu-Wei
;
Shieh, Jia-Min
;
Cheng, Shing-Song
Eutectic Sn-3.5wt.%Ag alloy is one of the most promising lead-free solders in low temperature processes for wafer bumping. Near eutectic composition of deposited alloy films could be readily acquired by pulse electroplating with a proper combination of active ingredients including K4P2O7, KI, Sn2P2O7, and AgI, as well as polyethylene glycol (PEG), with molecular weights of 200, 600, 2,000, and 4,000, as an inhibitive agent. Pulse electroplating was carried out with current in alternating polarity to conduct electroplating and electropolishing sequentially. As a result, alloy films with grains of less than 1 mu m and uniform surface morphology can be obtained. The addition of PEG was necessary for the stabilization of the plating baths to promote a wider process window for the desirable eutectic composition. Electrochemical characterization established that PEG with molecular weight of 4,000 exhibited the strongest inhibition behavior. In contrast, PEG with molecular weight of 200 demonstrated the least interference. Energy dispersive X-ray and differential scanning calorimeter data confirmed the formation of eutectic alloy as a function of deposition current density. X-ray diffraction results indicated that a biphasic structures of beta-Sn and epsilon-Ag3Sn was present in the as-deposited film.
Electromigration Immortality of Purely Intermetallic Micro -bump for 3D Integration
(2015)
Chen, Hsiao-Yun
;
Tung, Chih-Hang
;
Hsiao, Yi-Li
;
Wu, Jyun-lin
;
Yeh, Tung-Ching
The progress of three-dimensional integrated circuit (3D IC) micro-bump joining technology has led to an increased volume fraction of intermetallics (IMC) in the post reflow joints, to an extent that a solder micro-bump may consist almost entirely of IMCs. Therefore, the current carrying capability and electromigration (EM) life time of the purely IMC micro-joint needs to be understood as functions of stressing conditions and degradation mechanisms. Superior EM performance and robustness of IMC joints is demonstrated with no resistance fluctuation under ultra-high stressing condition for over 9000 WWhrs while solder micro-bumps led to an open failure within 500 hrs. At least an order of magnitude greater current carrying capability of IMC micro-joint compared with solder micro-joint is observed experimentally. The observed degradation mechanism is void formation within Al trace rather than damage inside IMC joint. IMC joint is not the EM reliability bottle neck of the test circuit.
Enhancing Sn-Ag Solder Joints Electromigration Lifetime via the Under-Bump-Metallization Structure Design
(2008)
Chen, Hsiao-Yun
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The authors demonstrate a Ni/Cu bilayer structure for the under-bump-metallization (UBM) in Sn-Ag flip chip solder joints to enhance the electronmogration lifetime. The Ni layer provides two main contributions for the lifetime improvement. First, since Ni is a good diffusion barrier for Cu, it reduces the electromigration failure by UBM dissolution. Furthermore, the Ni layer limits the current crowding effect by the current redistribution which has a good agreement with our three-dimensional simulation result. By applying Infrared Microscope (IR), the thermal distribution inside solder joints can be obtained as well. The hot spot temperature near the entrance point was 129 degrees C inside Cu UBM system, while it was only 122 degrees C in CuNi UBM system. In summery, the addition of higher resistivity Ni layer successfully redistributed the temperature and current route.
Failure induced by thermomigration of interstitial Cu in Pb-free flip chip solder joints
(2008-09-22)
Chen, Hsiao-Yun
;
Chen, Chih
;
Tu, King-Ning
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Failure induced by thermomigration in Pb-free SnAg flip chip solder joints has been investigated by electromigration tests under 9.7 x 10(3) A/cm(2) at 150 degrees C. The fast interstitial diffusion of Cu atoms from underbump metallization into Sn matrix caused void formation at the passivation opening on the chip side. The Cu diffusion was driven by a large thermal gradient and led to void formation even in the neighboring unpowered bumps. When the thermal gradient is above 400 degrees C/cm, theoretical calculation indicates that the thermomigration force is greater than the electromigration force at 9.7 x 10(3) A/cm(2) stressing. (C) 2008 American Institute of Physics.
Generic Rules to Achieve Bump Electromigration Immortality for 3D IC Integration
(2013)
Chen, Hsiao-Yun
;
Shih, Da-Yuan
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Wei, Cheng-Chang
;
Tung, Chih-Hang
;
Hsiao, Yi-Li
An immortal solder micro-bump (mu bump) electromigration (EM) lifetime has been demonstrated for 3D IC integration. This ultimate goal was achieved under strictly controlled conditions, including the optimal design of bump metallurgy, geometry, optimized processes, along with well-defined stressing conditions and manufacturing window. The current carrying capability and EM lifetime of mu bump have been investigated as functions of stressing conditions which are correlated with the degradation mechanisms. When stressed under the appropriate g conditions, all mu bump test samples survived prolonged stressing, some over 13,000 hours, without a failure. Cross-sectional analyses revealed that the entire solder joint almost all transformed into intermetallic compounds (IMCs) with very minor or no voids. The resistance plots showed an initial fast rise in resistance due to IMC formation, then gradually leveled off and eventually reached a steady state. The observed degradation mechanism is dominated by IMC formation, which is the same as that of the user conditions. On the other hand, void formation that eventually led to open failure was the dominant degradation mechanism when samples were aggressively stressed. In other words, when all other conditions were the same, the stressing conditions make a huge difference in determining between an almost immortal EM lifetime vs. a short lifetime using the same high quality mu bumps. The boundary that separates the stressing conditions is roughly defined and will be discussed. In addition, since full IMC mu bump will become inevitable in the future miniaturized solder interconnect structure, the EM behavior of IMC dominated mu bump has also been evaluated in this study. Under highly accelerated stressing conditions of 174 degrees C, at 1.6x10(5) A/cm(2) current density, the IMC dominated mu bumps were able to survive more than 600 hours and are still going strong. In comparison, solder mu bump failed quickly after just 107 hours when stressed under the same condition. This comparison study clearly demonstrated that IMC dominated joint has significantly higher current carrying capability than that of the solder joint. After reviewing all the data, we have concluded that the failure criteria for solder mu bump should be raised significantly higher than the 20% criteria traditionally used for the much larger C4 bumps.
In-situ Observation of the Failure Induced by Thermomigration of Interstitial Cu in Pb-free Flip Chip Solder Joints
(2009)
Chen, Hsiao-Yun
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Thermomigration in Pb-free SnAg solder joints is investigated during accelerated electromigration tests under 9.7 x 103 A/cm(2) at 150 degrees C. Different from Pb-containing solders, it is found that Cu-Sn intermetallic compounds (IMCs) migrate toward the cold end on the substrate end and thus voids accumulate in the passivation opening for the bump with current flowing from the substrate end to the chip end. Theoretical calculation indicates that the thermomigration force is greater than the electromigration force at a thermal gradient above 400 degrees C/cm. Copper atoms may migrate against current flow and become the dominant diffusion species. Also, the Q* can be estimated around I I kJ/mole. On the other hand, a control experiment shows that Ni-Sn IMCs did not migrate even tinder a huge thermal gradient over 1400 degrees C/cm.
Interfacial Reaction Between Eutectic Sn-Pb Solder and Electroplated-Ni as well as Electroless-Ni Metallization During Reflow
(2009-02-01)
Chen, Hsiao-Yun
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Electroplated-Ni (EP-Ni) has been adopted gradually as an underbump metallization layer due to its comparatively lower resistivity and higher deposition rate. In this study, the metallurgical reaction between eutectic Sn-Pb solder and EP-Ni as well as electroless-Ni (EL-Ni) was investigated at 200A degrees C, 210A degrees C, 220A degrees C, and 240A degrees C. It is found that the growth rate of Ni(3)Sn(4) intermetallic compound (IMC) on EP-Ni was slower than that on EL-Ni. The consumption rate is measured to be 0.97 x 10(-3) mu m/s and 1.48 x 10(-3) mu m/s for EP-Ni and EL-Ni, respectively. The activation energy is determined to be 51 kJ/mol and 48 kJ/mol for EP-Ni and EL-Ni, respectively. The dense structure of EP-Ni may be responsible for the lower IMC formation rate.
Kinetic study of eutectic Sn-3.5Ag and Electroplated Ni metallization in flip-chip solder joints
(2008)
Chen, Hsiao-Yun
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
It is well known that Ni and its alloys possess a lower reaction rate with Sn than Cu and Cu alloys. Therefore Ni-based under bump metallization have attracted attention in recent years. In this study, the diffusion-control led reaction between eutectic Sn-3.5Ag flip chip solder joints between electroplated-Ni (EP-Ni) and electroless-Ni (EL-Ni) has been investigated. Morphology and growth kinetics of the formed Ni(3)Sn(4) are study under different reflow temperatures, durations and times. The growth rates and the formation activation energy of Ni(3)Sn(4) IMC were estimated with EP-Ni and EL-Ni, respectively. The obtained data showed that the Ni(3)Sn(4) in the Sn-3.5Ag filp chip solder grow much faster with EP-Ni than EL-Ni UBM under the same condition. In summary, we can conclude that the slow reaction rate of EP-Ni provided a well-attached contact at the interface after 20 minutes reflow process and is better compare with EL-Ni UBM at the substrate.
Kinetic study of the intermetallic compound formation between eutectic Sn-3.5Ag alloys and electroplated Ni metallization in flip-chip solder joints
(2012-04-01)
Chen, Hsiao-Yun
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Ni-based under-bump metallization (UBM) has attracted wide attention due to its low reaction rate with Sn, compared with Cu and Cu alloy. In this study, the interfacial reactions between eutectic Sn-3.5Ag solder and Ni-based UBM, including electroplated Ni (EP-Ni) and electroless Ni (EL-Ni) are investigated. Morphology and growth kinetics of Ni3Sn4 intermetallic compounds are studied at different reflow temperatures and durations. The growth rate and the growth activation energy of Ni3Sn4 were measured for the two sets of samples. The activation energies are measured to be 25 kJ/mol and 38 kJ/mol for the Ni3Sn4 growth on EP-Ni and EL-Ni, respectively. The Ni3Sn4 on EP-Ni UBMs shows a slower growth rate and the Ni3Sn4/solder interface is void free even after 20-min reflow at 240 degrees C. On the other hand, the interface of Ni3Sn4/EL-Ni has a lot of microvoids after reflowing at 240 degrees C for 20 min.
Measurement of electromigration activation energy in eutectic SnPb and SnAg flip-chip solder joints with Cu and Ni under-bump metallization
(2010-09-01)
Chen, Hsiao-Yun
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Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Electromigration activation energy is measured by a built-in sensor that detects the real temperature during current stressing. Activation energy can be accurately determined by calibrating the temperature using the temperature coefficient of resistivity of an Al trace. The activation energies for eutectic SnAg and SnPb solder bumps are measured on Cu under-bump metallization (UBM) as 1.06 and 0.87 eV, respectively. The activation energy mainly depends on the formation of Cu-Sn intermetallic compounds. On the other hand, the activation energy for eutectic SnAg solder bumps with Cu-Ni UBM is measured as 0.84 eV, which is mainly related to void formation in the solder.
Musashi-1 Enhances Glioblastoma Cell Migration and Cytoskeletal Dynamics through Translational Inhibition of Tensin3
(2017-08-18)
Chen, Hsiao-Yun
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Lin, Liang-Ting
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Wang, Mong-Lien
;
Laurent, Benoit
;
Hsu, Chih-Hung
The RNA-binding protein Musashi-1 (MSI1) exerts essential roles in multiple cellular functions, such as maintenance of self-renewal and pluripotency of stem cells. MSI1 overexpression has been observed in several tumor tissues, including glioblastoma (GBM), and is considered as a well-established marker for tumor metastasis and recurrence. However, the molecular mechanisms by which MSI1 regulates cell migration are still undetermined. Here we reported that MSI1 alters cell morphology, promotes cell migration, and increases viscoelasticity of GBM cells. We also found that MSI1 directly binds to the 3'UTR of Tensin 3 (TNS3) mRNA, a negative regulator of cell migration, to inhibit its translation. Additionally, we identified that RhoA-GTP could be a potential regulator in MSI1/TNS3-mediated cell migration and morphological changes. In a xenograft animal model, high expression ratio of MSI1 to TNS3 enhanced GBM tumor migration. We also confirmed that MSI1 and TNS3 expressions are mutually exclusive in migratory tumor lesions, and GBM patients with MSI1(high)/TNS3(low) pattern tend to have poor clinical outcome. Taken together, our findings suggested a critical role of MSI1-TNS3 axis in regulating GBM migration and highlighted that the ratio of MSI1/TNS3 could predict metastatic and survival outcome of GBM patients.
Novel FFT Processor with Parallel-In-Parallel-Out in Normal Order
(2009)
Hu, Hsiang-Sheng
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Chen, Hsiao-Yun
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Jou, Shyh-Jye
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel FFT processor that can provide parallel-in-parallel-out in normal order is proposed for high throughput required OFDM communication system, such as discrete Fourier transform (DFT)-based channel estimation in IEEE 802.16c. The hardware implementation results show the proposed 1024-point FFT architecture can achieve the throughput rate up to 1.28 G samples/sec and the execution time down to 7.3 us when working at 160 MHz. When working at the system required 83.3 MHz, it consumes 21.7 mW with 134474 gates (including memory) that occupy 0.471 mm(2) by using 90 rim, IV CMOS process.
Novel programmable FIR filter based on higher radix recoding for low-power and high-performance applications
(2007)
Chen, Hsiao-Yun
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Jou, Shyh-Jye
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper proposes the novel programmable digital finite impulse response (FIR) filters for low-power and high-performance applications. The architecture is based on the higher radix recoding scheme which specifically targets the reduction of power consumption by decreasing partial products and precomputation sharing in each partial product. We extend higher radix recoding scheme with secondary radix recoding to further improve performance by reducing the propagation delay of precomputing odd multiples of the multiplicand. A 10-tap programmable FIR filter based on proposed schemes was design in TSMC 0.18-mu m technology. The performance and power consumption of the proposed schemes can improve about 40.9 similar to 65.5% and 28.3 similar to 50.2% over existing designs.
STBC-OFDM Downlink Baseband Receiver for Mobile WMAN
(2013-01-01)
Chen, Hsiao-Yun
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Lin, Jyun-Nan
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Hu, Hsiang-Sheng
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Jou, Shyh-Jye
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電子工程學系及電子研究所
This paper proposes a space time block code-orthogonal frequency division multiplexing downlink baseband receiver for mobile wireless metropolitan area network. The proposed baseband receiver applied in the system with two transmit antennas and one receive antenna aims to provide high performance in outdoor mobile environments. It provides a simple and robust synchronizer and an accurate but hardware affordable channel estimator to overcome the challenge of multipath fading channels. The coded bit error rate performance for 16 quadrature amplitude modulation can achieve less than 10(-6) under the vehicle speed of 120 km/hr. The proposed baseband receiver designed in 90-nm CMOS technology can support up to 27.32 Mb/s uncoded data transmission under 10 MHz channel bandwidth. It requires a core area of 2.41 x 2.41 mm(2) and dissipates 68.48 mW at 78.4 MHz with 1 V power supply.
Symbol and carrier frequency offset synchronization for IEEE802.16e
(2008)
Lin, Jyun-Nan
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Chen, Hsiao-Yun
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Wei, Ting-Chen
;
Jou, Shyh-Jye
;
電子工程學系及電子研究所
IEEE 802.16e standard has been proposed as a specification for the next generation wireless communication system. Synchronization plays an important role for a wireless receiver. Because the repetition of preamble is unapparent in orthogonal frequency division multiple access (OFDMA) modulation mode, a correlation based scheme like match filter is used to estimate the symbol boundary and integer carrier frequency offset (ICFO). In this paper, an effective hardware architecture of correlation is proposed. By adopting the modified algorithm, mass of multipliers are removed from hardware implementation. Design results show that 56% area reduction and 64% power saving are achieved. Moreover, a ping-pong algorithm is proposed to increase the accuracy of ICFO synchronization about two orders at most.
Thermomigration of Cu-Sn and Ni-Sn intermetallic compounds during electromigration in Pb-free SnAg solder joints
(2011-04-01)
Chen, Hsiao-Yun
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Thermomigration in Pb-free SnAg solder alloys is investigated during accelerated electromigration tests under 9.7 x 10(3) A/cm(2) at 150 degrees C. It is found that Cu-Sn intermetallic compounds (IMCs) migrate toward the cold end on the substrate side and, as a result, voids accumulate in the chip side for the bump with current flowing from the substrate end to the chip end. Theoretical calculations indicate that the thermomigration force is greater than the electromigration force at a thermal gradient above 400 degrees C/cm for this stressing condition. Copper atoms may migrate against current flow and become the dominant diffusion species. On the other hand, Ni-Sn IMCs did not migrate even under a huge thermal gradient of 1400 degrees C/cm. These findings provide more understanding on the thermomigration of metallization materials in flip-chip solder joints.
Thermomigration of Ti in flip-chip solder joints
(2012-05-01)
Chen, Hsiao-Yun
;
Lin, Han-Wen
;
Liu, Chien-Min
;
Chang, Yuan-Wei
;
Huang, Annie T.
Titanium has a very large heat of transport value of -768 kJ mol(-1). However, thermomigration of Ti in solder joints has not been examined. In this study, void formation was observed in non-current-stressed Al traces during electromigration and thermomigration tests of SnAg solder joints. Voids formed inside the traces located above the solder bumps with no current flow. We found that Ti thermomigration occurred in the joint, resulting in the reaction of Al and Cu, leaving voids behind in the Al trace. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.