Jong-Tae Moon

On the formation of MoSi2 by self-propagating high-temperature synthesis

The formation mechanism of MoSi{sub 2} by self-propagating high-temperature synthesis (SHS) was studied by quenching the reaction front into liquid nitrogen or in a copper block. The microstructural analysis of the front indicated that the formation of MoSi{sub 2} occurs via dissolution of Mo into Si melt followed by MoSi{sub 2} precipitation. The effects of processing variables including Mo particle size, preheating temperature, and diluent content on the MoSi{sub 2} particle size were discussed, based on the mechanism proposed in this study.

The interface behavior of the Cu-Al bond system in high humidity conditions

Copper (Cu) wire has been highlighted as a low cost material for use in thermosonic ball bonding for various package (PKG) groups. This wire has already been applied in high-end PKGs such as BGA, QFP and QFN in mass production, and the volume is feasible. Not only the advantage of a low cost material, but Cu wire has other merits which include higher electrical conductivity and a much slower inter-metallic compound (IMC) growth rate than Gold (Au) wire.

System-on-packaging with electro-absorption modulator for 60 GHz band radio-over-fiber link

We developed a system-on-packaging (SoP) with an electro-absorption modulator (EAM) for a 60 GHz band radio-over-fiber (RoF) link. It consists of an EAM device, a microstrip filter, and a low noise amplifier (LNA). The microstrip filter was used to achieve the impedance matching between the EAM device and the LNA and to reject the local oscillator (LO) frequency of the heterodyne system. The frequency response and the effect of the EAM bias voltage of a simple RF/optical link were measured. A 60 GHz band RoF link with 2.4 GHz intermediate frequency (IF) was prepared to measure the transmission characteristics of 16 QAM data

Optimization of ultrasound and bond force to reduce pad stress in thermosonic Cu ball bonding

Ball bonding processes are optimized on Al pads with a 25.4 µm diameter Cu wire to obtain maximum average shear strengths of at least 120 MPa. To quantify the direct effect of bond force and ultrasound on the pad stress, ball bonding is performed on test pads with piezoresistive microsensors integrated next to the pad and the real-time ultrasonic signals are measured. By using a lower value of bond force combined with reduced ultrasound level, the pad stress can be reduced by 30%. An ultrasound/bond force process window for low-stress copper ball bonding is determined, which shows that a proper optimization of ultrasound and bond force leads to Cu ball bonds of high quality while transmitting lower stress to the pad during the bonding process.

Fabrication and Characteristics of 40-Gb/s Traveling-Wave Electroabsorption Modulator-Integrated DFB Laser Modules

We have developed 40-Gb/s traveling-wave electroabsorption-modulator-integrated distributed feedback laser (TW-EML) modules using several advanced technologies. First, we have adopted a selective area growth (SAG) method in the fabrication of the 40-Gb/s EML device to provide active layers for the laser and the electroabsorption modulators (EAMs) simultaneously. The fabricated device shows that the measured 3-dB bandwidth of electrical-to-optical (E/O) response reaches about 45 GHz and the return loss (S11) is kept below -10 dB up to 50 GHz. For the module design of the device, we mainly considered electrical and optical factors. The measured S11 of the fabricated 40 Gb/s TW-EML module is below -10 dB up to about 30 GHz and the 3-dB bandwidth of the E/O response reaches over 35 GHz. We also have developed two types of coplanar waveguide (CPW) for the application of the driver amplifier integrated 40 Gb/s TW-EML module, which is a system-on-package (SoP) composed of an EML device and a driver amplifier device in a module. The measured S11 of the two-step-bent CPW is below -10 dB up to 35 GHz and the measured S11 of the parallel type CPW is below -10 dB up to 39 GHz.

System-on-Packaging with Electroabsorption Modulator for a 60-GHz Band Radio-Over-Fiber Link

A system-on-packaging (SoP) with an electroabsorption modulator (EAM) for a 60 GHz band radio-over-fiber (RoF) link is described. The system consists of an EAM device, a microstrip filter, and a low noise amplifier (LNA). The microstrip filter was used to achieve impedance matching between the EAM device and the LNA and to reject the local oscillator (LO) frequency of the heterodyne system. The frequency response and the effect of the EAM bias voltage were measured for a simple RF/optical link. A 60 GHz band RoF link with 2.5 GHz intermediate frequency (IF) was prepared to measure the transmission characteristics of the 16 QAM data.

Development of Packaging Technologies for High-Speed (

We developed high-speed optoelectronics packaging technologies for a waveguide photodiode and a traveling wave electro-absorption modulator device for 40-Gb/s digital communication systems. The effects of the device and the packaging designs on the broadband performance were investigated to optimize broadband characteristics. For the receiver, inductive peaking was used for bandwidth control and an internal bias tee was implemented; in addition, two types of preamplifier devices were used to develop high-gain receiver and wide-bandwidth receiver. In the optical-to-electrical response, a 3-dB bandwidth of the high-gain module was about 32 GHz as compared to 42 GHz for the wide-bandwidth module. The clear 40-Gb/s nonreturn-to-zero (NRZ) eye diagrams showed a good system applicability of these modules. In addition, an optimized modulator module showed a 3-dB bandwidth of 38 GHz in the electrical-to-optical response, an electrical return loss of less than 10 dB at up to 26 GHz, an rms jitter of 1.832 ps, and an extinction ratio of 5.38 dB in a 40-Gb/s NRZ eye diagram

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Integration of a 40-Gb/s electroabsorption modulator integrated distributed feedback (DFB) laser (EML) module with a driver amplifier and bias tee was investigated. For the EML fabrication the selective area growth (SAG) technique was adopted for the first time. It is shown that, with the SAG technique, the 3-dB bandwidth of about 45 GHz was measured in the electrical to optical response, and the return loss (S11) of below -10 dB was achieved for up to 50 GHz . To integrate a bias tee within the module, a right-angle bent coplanar waveguide (CPW) was developed. The right-angle bent CPW was characterized with S11 of below - 10 dB for up to 35 GHz and insertion loss (S21) of about -1.4 dB for up to 40 GHz . The whole integrated module including the EML, a driver amplifier, and bias tee was characterized under the conditions of an operating temperature of 25degC, the modulator bias of 1.4 V, and the DFB laser current of 40 mA. S11 of below -10 dB was obtained for up to 14 GHz and the measured electrical-to-optical response has 3-dB bandwidth of about 20 GHz.

Gb/s) Optical Modules

TWEAM modulator modules optimized in 40 GHz and 60 GHz band, respectively, were developed. The bandwidth at the operating frequency can be controlled with the termination resistance. Impedance matching of the modules was achieved using the double stub design and the laser trimming process. The measured Electrical-to-optical (E/O) response showed the increase in the response near 40 GHz and 60 GHz, respectively. The third-order inter-modulation distortion (IMD3) was below -65 dBc at -7 dBm RF input and spurious free dynamic range (SDRF) was about 108 dB Hz/sup 2/3/.

Integration and Characteristics of 40-Gb/s Electroabsorption Modulator Integrated Laser Module With a Driver Amplifier and Bias Tees

SnAgCu solder is most popular solder composition system in the package industry. Therefore, SnAgCu solder has been studied by many researchers to improve its properties. In this study, we ran tests to verify the effect of Al additive metal in SnAgCu solder in term of wettability and drop impact reliability. The test solder compositions were Sn1.0Ag0.5Cu solder (Ref. solder) and Sn1.0Ag0.5Cu-xwt%Al solder and Al contents were 0.005, 0.01, 0.02, 0.1, and 0.12wt%.