서지주요정보
인듐 범프를 이용한 VCSEL 어레이의 플립칩 본딩 최적화 = Optimization of flip chip bonding for a VCSEL array using indium bumps
서명 / 저자 인듐 범프를 이용한 VCSEL 어레이의 플립칩 본딩 최적화 = Optimization of flip chip bonding for a VCSEL array using indium bumps / 주건모.
저자명 주건모 ; Chu, Kun-Mo
발행사항 [대전 : 한국과학기술원, 2003].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8014024

소장위치/청구기호

학술문화관(문화관) 보존서고

MMS 03038

SMS전송

도서상태

이용가능

대출가능

반납예정일

초록정보

Vertical-Cavity Surface-Emitting Laser (VCSEL)is a useful light source that can be applied to chip-to-chip and board-to-board optical data link. To package the developed optical interconnect, a VCSEL array was flip-chip bonded on a transparent glass substrate that is a propagation path of laser beam and also support waveguide. The size of (1x4)VCSEL array used is 1000$\mu$m×70$\mu$m , and 200 $\mu$m thick. In dealing with such a small VCSEL array, Under Bump Metallurgy (UBM) process is difficult. When the VCSEL is flip chip bonded without UBM, the VCSEL`s window can be damaged because solders spread to window along the metal pad and cover it. If subsequent process temperature is higher than 250$^\circ$C, the performance of VCSEL will be degraded and waveguide can be damaged during the flip chip bonding. In the present study, we tried a flip chip bonding by using indium solder bumps to overcome difficulties. In the part of glass substrate, indium solders were deposited on top of Au/Ni/Ti UBM pad by thermal evaporation method. Solder bumps were formed by using lift-off method. Adopting indium can prevent a degradation of VCSEL by decreasing the processing temperature below 150$^\circ$C and decrease the bonding pressure because indium is malleable. To optimize the flip chip bonding condition of VCSEL array, the die shear test and the spreading test for indium solder bump were carried out. The die shear strength was increased as the bonding temperature and pressure were increased. Except some cases, indium solder bump didn`t spread much along the metal line or chip pad during the flip-chip bonding and reflow process. During the die shear test, facture occured mostly between indium solder bump and VCSEL chip pad. In the soldering operation, indium easily forms oxides that adhere onto the indium solder bump surface and prevent the solder solution from having contact with the VCSEL chip pad to be joined. To prevent oxidation of indium bump and increase the adhesion between indium bump and VCSEL chip pad, thin silver layer was coated onto the indium surface. In this study it was found that the optimum condition of flip chip bonding for VCSEL array using indium bump is 150$^\circ$C, 500 gf. Also thin silver layer coating is very effective method to prevent oxidation of indium bump and enhance the adhesion between indium bump and VCSEL chip pad. By preventing indium solder from oxidation in bonding process, flux is no longer needed. In addition, surface morphology of indium solder could be improved by coating thin silver layer. Finally, VCSEL array was flip chip bonded on the fused silica substrate by using the optimum bonding condition. To drive VCSEL array, the substrate was bonded on the PCB test board by wire bonding method. As a result, uniform laser beam propagation profile and power could be obtained in this bonding condition.

서지기타정보

서지기타정보
청구기호 {MMS 03038
형태사항 iv, 94 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Kun-Mo Chu
지도교수의 한글표기 : 전덕영
지도교수의 영문표기 : Duk-Young Jeon
학위논문 학위논문(석사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 : p. 93-94
주제 수직공진형 표면방출레이저
인듐솔더범프
플립칩
광연결
솔더댐

VCSEL
indium solder bump
flip chip
optical interconnection
UBM
silver
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