TY - GEN
T1 - Electromigration in Ni/Sn intermetallic micro bump joint for 3D IC chip stacking
AU - Lin, Yu-Min
AU - Zhan, Chau-Jie
AU - Juang, Jing-Ye
AU - Lau, John H.
AU - Chen, Tai-Hong
AU - Lo, Robert
AU - Kao, M.
AU - Tian, Tian
AU - Tu, King-Ning
N1 - Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].
PY - 2011
Y1 - 2011
N2 - In this study, we used a chip-on-chip test vehicle with 30μm pitch lead-free solder micro bump to study the electromigration reliability of solder micro bump interconnection used for 3D chip stacking. The structure of micro bump composed of Sn2.5Ag solder material with Cu/Ni under bump metallization (UBM) was selected. Two types of interconnection were chosen to evaluate the effect of the joint structure on electromigration behavior. The type I was the chip stacking sample with the IMC / Sn (5.m thick) / IMC joint structure, while the type II was the sample with fully transformed Ni3Sn4 intermetallic (IMC) joints made by the post-treatment of long time thermal aging. Electromigration test was performed on the four point Kelvin structure and daisy-chain structure under the current stressing of 104~105 A/cm2 at an ambient temperature of 150°C. During the electromigration test, the resistance increase was in-situ monitored to determine the definite time to failure. The microstructure evolution was also examined at different stages of joint resistance increase. From the testing results, the rapid increase of joint resistance was found at the early stage under current stressing in the type I micro bump. After that, the joint resistance increase became slower. This mild increasing stage was much longer than the early stage. For the type II sample, however, the resistance increasing rate was quiet lower than that of the type I sample at the identical testing time. With a higher current density in the order of 105 A/cm2 in the micro joint, the effect of joule heating caused the damage happened in Al trace and Cu UBM while the residual Sn solder had been transformed to be Ni3Sn4 IMC totally and few voids were found around IMC by the microstructure observation. When applied a current density in the order of 104 A/cm2 on the micro joint, the residual Sn was also fully transformed to be IMC. However, the failure mode of the micro joint is not clear yet because the experiments are still on-going. The resistance variation is showing a steady state under such a condition of current stressing and so far no open failure happened. © 2011 IEEE.
AB - In this study, we used a chip-on-chip test vehicle with 30μm pitch lead-free solder micro bump to study the electromigration reliability of solder micro bump interconnection used for 3D chip stacking. The structure of micro bump composed of Sn2.5Ag solder material with Cu/Ni under bump metallization (UBM) was selected. Two types of interconnection were chosen to evaluate the effect of the joint structure on electromigration behavior. The type I was the chip stacking sample with the IMC / Sn (5.m thick) / IMC joint structure, while the type II was the sample with fully transformed Ni3Sn4 intermetallic (IMC) joints made by the post-treatment of long time thermal aging. Electromigration test was performed on the four point Kelvin structure and daisy-chain structure under the current stressing of 104~105 A/cm2 at an ambient temperature of 150°C. During the electromigration test, the resistance increase was in-situ monitored to determine the definite time to failure. The microstructure evolution was also examined at different stages of joint resistance increase. From the testing results, the rapid increase of joint resistance was found at the early stage under current stressing in the type I micro bump. After that, the joint resistance increase became slower. This mild increasing stage was much longer than the early stage. For the type II sample, however, the resistance increasing rate was quiet lower than that of the type I sample at the identical testing time. With a higher current density in the order of 105 A/cm2 in the micro joint, the effect of joule heating caused the damage happened in Al trace and Cu UBM while the residual Sn solder had been transformed to be Ni3Sn4 IMC totally and few voids were found around IMC by the microstructure observation. When applied a current density in the order of 104 A/cm2 on the micro joint, the residual Sn was also fully transformed to be IMC. However, the failure mode of the micro joint is not clear yet because the experiments are still on-going. The resistance variation is showing a steady state under such a condition of current stressing and so far no open failure happened. © 2011 IEEE.
UR - https://www.scopus.com/pages/publications/79960416815
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-79960416815&origin=recordpage
U2 - 10.1109/ECTC.2011.5898537
DO - 10.1109/ECTC.2011.5898537
M3 - RGC 32 - Refereed conference paper (with host publication)
SN - 9781612844978
T3 - Proceedings - Electronic Components and Technology Conference
SP - 351
EP - 357
BT - 2011 IEEE 61st Electronic Components and Technology Conference, ECTC 2011
T2 - 2011 61st Electronic Components and Technology Conference, ECTC 2011
Y2 - 31 May 2011 through 3 June 2011
ER -