Browsing by Author "Hsu, Li-Han"

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60 GHz broadband Ms-to-CPW hot-via flip chip interconnects
(2007-11-01)
Wu, Wei-Cheng
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Hsu, Li-Han
;
Chang, Edward Yi
;
Kaernfelt, Camilla
;
Zirath, Herbert
In this letter, the microstrip-to-coplanar waveguide (MS-to-CPW) hot-via flip chip interconnect has been experimentally demonstrated to have broadband performance from dc to 67 GHz. The interconnect structures with the hot-via transitions were first designed and optimized by using the electromagnetic simulation tool. Three types of designs were investigated in this letter. The interconnect structures were then fabricated and radio frequency (RF) tested up to 67 GHz. The optimized interconnect structure with the compensation design demonstrated excellent RF characteristics with the insertion loss less than 0.5 dB and the return loss below 18 dB over a very broad bandwidth from dc to 67 GHz. This is to our knowledge the best result reported for this frequency range.
An 80 nm In(0.7)Ga(0.3)As MHEMT with Flip-Chip Packaging for W-Band Low Noise Applications
(2010-01-01)
Wang, Chin-Te
;
Kuo, Chien-I
;
Lim, Wee-Chin
;
Hsu, Li-Han
;
Hsu, Heng-Tung
The fabrication process of an 80 nm In(0.7)Ga(0.3)As MHEMT device with flip-chip packaging on Al(2)O(3) substrate is presented. The flip-chip packaged device exhibited good dc characteristics with high I(DS) = 425 mA/mm and high g(m) = 970 mS/mm at V(DS) = 1.5 V. Besides, the RF performances revealed high gain of 10 dB at 50 GHz and low minimum noise figure (NF(min))below 2 dB at 60 GHz, showing the feasibility of flip-chip packaged In(0.7)Ga(0.3)As MHEMT device for low noise applications at W-band.
An 80 nm In0.7Ga0.3As MHEMT with Flip-Chip Packaging for W-Band Low Noise Applications
(2010-01-01)
Wang, Chin-Te
;
Kuo, Chien-, I
;
Lim, Wee-Chin
;
Hsu, Li-Han
;
Hsu, Heng-Tung
The fabrication process of an 80 nm In0.7Ga0.3As MHEMT device with flip-chip packaging on Al2O3 substrate is presented. The flip-chip packaged device exhibited good dc characteristics with high I-DS = 425 mA/mm and high g(m) = 970 mS/mm at V-DS = 1.5 V. Besides, the RF performances revealed high gain of 10 dB at 50 GHz and low minimum noise figure (NFmin)below 2 dB at 60 GHz, showing the feasibility of flip-chip packaged In0.7Ga0.3As MHEMT device for low noise applications at W-band.
Design and Fabrication of 0/1-Level RF-Via Interconnect for RF-MEMS Packaging Applications
(2010-02-01)
Hsu, Li-Han
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Wu, Wei-Cheng
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Chang, Edward Yi
;
Zirath, Herbert
;
Wu, Yun-Chi
This paper presents the parametric study of RF-via (0-level) and flip-chip bump (1-level) transitions for applications of packaging coplanar RF-MEMS devices. The key parameters were found to be the bumps' and vias' positions and the overlap of the metal pads, which should be carefully considered in the entire two levels of packages. The length of the backside transmission line, determining the MEMS substrate area, showed minor influence on the interconnect performance. With the experimental results, the design rules have been developed and established. The optimized interconnect structure for the two levels of packages demonstrates the return loss beyond 15 dB and the insertion loss within 0.6 dB from dc to 60 GHz.
Design of Flip-Chip Interconnect Using Epoxy-Based Underfill Up to V-Band Frequencies With Excellent Reliability
(2010-08-01)
Hsu, Li-Han
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Wu, Wei-Cheng
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Chang, Edward Yi
;
Zirath, Herbert
;
Hu, Yin-Chu
This study demonstrates a flip-chip interconnect with epoxy-based underfill (epsilon(r) = 3.5 and tan delta = 0.02 at 10 MHz) for packaging applications up to V-band frequencies. To achieve the best interconnect performance, both the matching designs on GaAs chip and Al(2)O(3) substrate were adopted with the underfill effects taken into consideration. The optimized flip-chip interconnect showed excellent performance from dc to 67 GHz with return loss below -20 dB and insertion loss less than 0.6 dB. Furthermore, the dielectric loss induced by the underfill was extracted from measurement and compared with the simulation results. The reliability tests including 85 degrees C/85 % relative humidity test, thermal cycling test, and shear force test were performed. For the first time, the S-parameters measurement was performed to check the flip-chip reliability, and no performance decay was observed after 1000 thermal cycles. Moreover, the mechanical strength was improved about 12 times after the underfill was applied. The results show that the proposed flip-chip architecture has excellent reliability and can be applied for commercial applications.
Design, Fabrication, and Characterization of Novel Vertical Coaxial Transitions for Flip-Chip Interconnects
(2009-05-01)
Wu, Wei-Cheng
;
Chang, Edward Yi
;
Hwang, Ruey-Bing
;
Hsu, Li-Han
;
Huang, Chen-Hua
In this paper, a novel transition design using vertical "coaxial transition" for coplanar waveguide (CPW-to-CPW) flip-chip interconnect is proposed and presented for the first time. The signal continuity is greatly improved since the coaxial-type transition provides more return current paths compared to the conventional transition in the flip-chip structure. The proposed coaxial transition structure shows a real coaxial property from the 3-D electromagnetic wave simulation results. The design rules for the coaxial transition are presented in detail with the key parameters of the coaxial transition structure discussed. For demonstration, the back-to-back flip-chip interconnect structures with the vertical coaxial transitions have been successfully fabricated and characterized. The demonstrated interconnect structure using the coaxial transition exhibits the return loss below 25 dB and the insertion loss within 0.4 dB from dc to 40 GHz. Furthermore, the measurement and simulation results show good agreement. The novel coaxial transition demonstrates excellent interconnect performance for flip-chip interconnects and shows great potential for flip-chip packaging applications at millimeter waves.
Design, Fabrication, and Reliability of Low-Cost Flip-Chip-On-Board Package for Commercial Applications up to 50 GHz
(2012-03-01)
Hsu, Li-Han
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Oh, Chee-Way
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Wu, Wei-Cheng
;
Chang, Edward Yi
;
Zirath, Herbert
This paper presents a flip-chip-on-board (FCOB) packaging technology using a Rogers RO3210 laminate for microwave applications. Compared to the conventional microwave packaging architecture, the proposed FCOB technology skips one level of the ceramic package and thus results in lower reflections and manufacturing costs. To fulfill the small dimension requirement on printed circuit boards, the coplanar waveguide (CPW) transmission line and flip-chip bump were fabricated on a high-k RO3210 board (epsilon(r) = 10.2) with photolithography and electroplating. The GaAs chip patterned with the CPW line was then flip-chip-mounted onto the RO3210 laminate board. This structure displayed excellent performance from dc to 50 GHz with a return loss S-11 greater than 18 dB and insertion loss S-21 less than 0.5 dB. Meanwhile, the flip-chip bonding of the in-house-fabricated In0.52Al0.As-48/In0.6Ga0.4As metamorphic high-electron-mobility transistor devices on RO3210 also displayed excellent gain performance with a small degradation of 1 dB from dc to 40 GHz, showing the potential of implementing microwave integrated circuits on RO3210. To enhance the mechanical reliability, an epoxy-based underfill was injected into the flip-chip assemblies. Thermal cycling tests were performed to test the interconnect reliability, and the results indicated that the samples passed the thermal cycling test at least up to 600 cycles, showing excellent reliability for commercial applications. To the best of the authors' knowledge, this is the first study that evaluates the use of the RO3210 laminate for microwave flip-chip in open literature.
Evaluation of Electrical Characteristics of the Copper-Metallized SPDT GaAs Switches at Elevated Temperatures
(2008-09-01)
Wu, Yun-Chi
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Chang, Edward Yi
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Lin, Yueh-Chin
;
Hsu, Li-Han
;
材料科學與工程學系
Copper-metallized AlGaAs/InGaAs pseudomophic high-electron mobility transistor single-pole-double-throw (SPDT) switches utilizing platinum (Pt, 70 nm) as the diffusion barrier have been studied and demonstrated. As compared with the Au-metallized switches, the Cu-metallized SPDT switches exhibited comparable performance with insertion loss less than 0.5 dB, return loss larger than 20 dB, isolation larger than 35 dB, and the input power for 1-dB compression (input P-1 (dB)) of 28.3 dBm at 2.5 GHz. In order to evaluate the temperature-dependent impact on dc and RF characteristics of the copper-metallized switches for high-temperature applications, the switches have been tested at different temperatures. The device exhibits low thermal threshold coefficients (delta V-th/delta T) of -0.25 mV/K from 300 K to 500 K, good microwave performance at 380 K with insertion loss less than 0.5 dB, isolation higher than 40 dB, and the input power for I-dB compression (input P-1 (dB)) of 28.45 dBm at 2.5 GHz. To test the thermal stability of the Pt diffusion barrier, these switches were annealed at 250 degrees C for 20 h. After the annealing, the switches showed no degradation of the dc characteristics. In addition, after a high temperature storage life environment test at 150 degrees C, these copper-metallized switches remained capable of excellent power handling. To test the operation reliability of the copper-metallized switches, the copper-metallized switches were subjected to ON/OFF (control voltage = +3/0 V exchange) stress test for 24 h at room temperature. The devices maintained excellent RF characteristics after the stress test. Consequently, it is successfully demonstrated through these tests that copper metallization using Pt as the diffusion barrier could be applied to the GaAs monolithic microwave integrated circuit switch fabrication with good RF performance, high-temperature characteristics, and reliability.
Evaluation of TiN/Cu Gate Metal Scheme for AlGaN/GaN High-Electron-Mobility Transistor Application
(2013-09-01)
Lin, Yueh-Chin
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Chang, Chih-Hsiang
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Li, Fang-Ming
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Hsu, Li-Han
;
Chang, Edward Yi
The TiN/Cu metal scheme as gate metal for AlGaN/GaN high-electron-mobility transistors (HEMTs) is investigated. The copper-gated devices show comparable DC characteristics to the conventional Ni/Au-gated devices. No obvious of changes in I-DS and I-GS were observed for the device after being stressed at V-DS = 200 and V-GS = -5 V for 32 h. The thermal stability test indicates comparable Schottky barrier height for the TiN/Cu gate metal on GaN before and after 250 degrees C annealing for 1 h. Overall, the AlGaN/GaN HEMT with the TiN/Cu gate metal structure demonstrates excellent device DC characteristics, good thermal stability, and stable performance after a high-voltage stress test. (c) 2013 The Japan Society of Applied Physics
Flip-Chip Packaging of In0.6Ga0.4As MHEMT Device on Low-Cost Organic Substrate for W-Band Applications
(2010)
Lim, Wee Chin
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Wang, Chin-Te
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Kuo, Chien-I
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Hsu, Li-Han
;
Tsai, Szu-Ping
A discrete low noise In0.6Ga0.4As MHEMT device with 150 nm gate length was flip-chip assembled on the low-cost RO3210 organic substrate for wireless communication applications. The measured DC characteristics were very similar before and after flip-chip assembly. The flip-chip packaged MHEMT device showed a high drain current density of 516 mA/mm and a maximum transconductance of 576 mS/mm at a V-DS of 0.8 V. The insertion gain of the flip-chip packaged device was decayed less than 2 dB up to 100 GHz as compared to the data of bare die. Moreover, the measured minimum noise figure was less than 2 dB as measured at V-DS of 0.7 V and V-GS of -0.7 V in the frequency range from 20 to 64 GHz for the device after flip-chip assembly. The excellent performance of the flip-chip packaged MHEMT device demonstrates the feasibility of using low cost organic substrate for high frequency applications up to W band.
Flip-Chip Packaging of Low-Noise Metamorphic High Electron Mobility Transistors on Low-Cost Organic Substrate
(2011-09-01)
Wang, Chin-Te
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Kuo, Chien-I
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Hsu, Heng-Tung
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Chang, Edward Yi
;
Hsu, Li-Han
The rapid growth of high-frequency wireless communication demands high-performance packaging structures at low cost. A flip-chip interconnect is one of the most promising technologies owing to its low parasitic effect and high performance at high frequencies. In this study, the in-house fabricated In(0).(6)Ga(0.4)As metamorphic high electron mobility transistor (mHEMT) device was flip-chip-assembled using a commercially available low-cost organic substrate. The packaged device with the optimal flip-chip structure exhibited almost similar DC and RF results to the bare die. An exopy-based underfill was applied to the improvement of reliability with almost no degradation of the electrical characteristics. Measurement results revealed that the proposed packaging structure maintained a low minimum noise figure of 3 dB with 6 dB associated gain at 62 GHz. Such a superior performance after flip-chip packaging demonstrates the feasibility of the proposed low-cost organic substrate for commercial high-frequency applications up to the W-band. (C) 2011 The Japan Society of Applied Physics
Flip-Chip-Based Multichip Module for Low Phase-Noise V-Band Frequency Generation
(2010-09-01)
Hsu, Li-Han
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Kuylenstierna, Dan
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Kozhuharov, Rumen
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Gavell, Marcus
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Karnfelt, Camilla
This paper reports on a flip-chip (FC)-based multichip module (MCM) for low phase-noise (PN) V -band frequency generation. A high-performance x8 GaAs metamorphic high-electron mobility transistor monolithic microwave integrated circuit (MMIC) multiplier and a low PN 7-GHz GaAs InGaP heterojunction bipolar transistor (HBT) MMIC oscillator were used in the module. The microstrip MMICs were FC bonded to an Al(2)O(3) carrier with patterns optimized for low-loss transitions. The FC-based module was experimentally characterized to have a PN of -88 dBe/Hz @ 100-kHz offset and -112 dBc/Hz @ 1-MHz offset with an output power of 11 dBm. For comparison, the MMICs were also FC bonded as individual chips and the performance was compared with the bare dies without FC bonding. It was verified that the FC bonding has no detrimental effect on the MMIC performance. The tests revealed that the FC module provided improved performance. To our best knowledge, this is the first FC-based module for millimeter-wave frequency generation. The module also presents one of the best PN reported for millimeter-wave frequency sources.
High Frequency Flip Chip Package Process of Polymer Substrate and Structure thereof
(2010-09-30)
Chang, Edward-yi
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Hsu, Li-Han
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Oil, Chee-Way
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Wu, Wei-Cheng
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Wang, Chin-te
In a high frequency flip chip package process of a polymer substrate and a structure thereof, the structure is a one-layer structure packaged by a high frequency flip chip package process to overcome the shortcomings of a conventional two-layer structure packaged by the high frequency flip chip package process. The conventional structure not only incurs additional insertion loss and return loss in its high frequency characteristic, but also brings out a reliability issue. Thus, the manufacturing process of a ceramic substrate in the conventional structure still has the disadvantages of a poor yield rate and a high cost.
Investigation of the Flip-Chip Package With BCB Underfill for W-Band Applications
(2014-01-01)
Wang, Chin-Te
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Hsu, Li-Han
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Wu, Wei-Cheng
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Hsu, Heng-Tung
;
Chang, Edward Yi
Flip-chip package has great potential for use in millimeter-wave applications. However, the coefficient of thermal expansion mismatch between the chip and the substrate usually generates thermal stresses that fracture the flip-chip structure. The use of underfills with low dielectric loss is essential to improve the mechanical strength and reliability of the flip-chip package. Benzocyclobutene (BCB) was used in this study as the underfill material for the flip-chip structure using the no-flow process. The flip-chip structure with BCB injection provides good RF performance with a return loss of better than 18 dB and an insertion loss of 0.6 dB up to 100 GHz, in addition to a lower dielectric loss. Furthermore, thermal cycle and shear force tests show that the underfill injection can significantly improve the reliability of a flip-chip package.
The Circle-grid Electrode on Concentrated GaAs Solar Cells Efficiency
(2011)
Chung, Chen-Chen
;
Yu, Hung-Wei
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Hsu, Li-Han
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Kuo, Chien-I
;
Nguyen-Hong Quan
The relationship between front contact pattern of GaAs single-junction solar cell with conversion efficiency at different concentration ratios is studied in this paper. Five different front circle-grid patterns were designed and patterned on the in-house fabricated single junction GaAs solar cells. At high light concentration ratio, the cell efficiency is strongly dependent on the series resistance of the electrode. At the same time, the thermal effect should also be taken into consideration, especially when a device is operating under high concentration ratio. Therefore, the aim of this work is to find a suitable front contact pattern for a GaAs single-junction solar cell to increase the conversion efficiency under high concentration solar radiation. It is found that the device with proper pattern design geometrical shadowing factor of 7.1% has the best cell efficiency of 27.05% at CR>100x, AM1.5G.
Vertical Transmission Structure
(2009-10-29)
Chang, Edward Yi
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Wu, Wei-Cheng
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Hwang, Ruey-Bing
;
Hsu, Li-Han
A vertical transmission structure for high frequency transmission lines includes a conductive axial core and a conductive structure surrounding the conductive axial core. The vertical transmission structure is applied to a high-frequency flip chip package for reducing the possibility of underfill from coming in contact with the conductive axial core.