| AVS 59th Annual International Symposium and Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS+BI-TuM |
| Session: | Practical Surface Analysis |
| Presenter: | J.C. Lee, Samsung Advanced Institute of Technology, Republic of Korea |
| Authors: | J.C. Lee, Samsung Advanced Institute of Technology, Republic of Korea Y.K. Kyoung, Samsung Advanced Institute of Technology, Republic of Korea I.Y. Song, Samsung Advanced Institute of Technology, Republic of Korea S. Iida, Ulvac Phi, Japan |
| Correspondent: | Click to Email |
Surface topography is often important role in the functionality and activity of electronic devices including MEMS, composite materials, catalysts, sensors, biomedical, and packaging of semiconductor devices. Especially, trench structure such as via hole or etched pattern is one of the important processes in the through silicon via or ball grid array. If there is contaminated on the wall or bottom of via hole, it may cause contact failure between integrated circuits and printed circuit board (PCB) because of increasing contact resistance. For the recent decade, many research activities are focused on the quantitative analyses of topographic samples using TOF-SIMS. However, the most of results were focused on the nanowire, nano particle, and etched surface, it is relatively rarely dealt with the trench shape sample. It is not easy to characterize the contaminant level of ~ppm or less on the bottom of trench shape sample such as via hole. It is well known that a ToF-SIMS is one of powerful tools to analyze organic contaminants. However there are some limitations to apply it to the trench shape sample because of high sample bias voltage and short focal length of emersion lens of ToF-SIMS analyzer. If we want to characterize contaminants on the bottom of via hole using a ToF-SIMS, the side wall of via hole should be removed by mechanical treatments. In this study, we aim to establish an optimized method that is able to characterize the bottom and wall of via hole of BGA using ToF-SIMS without any mechanical or chemical treatments. This is performed by combining ToF-SIMS experiments using via hole systems with computer modeling using SIMION.
For this study, trench structure samples with the diameter of 90µm and width of 90µm were used for TOF-SIMS imaging. Via holes were fabricated by laser drilling method. Samples were mounted on the sample holders which were specially designed with tilted angles of 15, 28, and 40 degrees surfaces for this experiment. Secondary ion trajectory and potential contour were calculated using SIMION for 0, 15, 28, 40 degree tilted samples for understanding the angle dependence of field effects.According to the simulation results, secondary ions ejected from near corner between wall and bottom of via hole are aimed to diagonal direction due to Coulomb repulsive force between secondary ions and wall of via hole. When specially designed 40 degree tilted angle sample holder which is based on simulation result is used, the bottom and wall of via hole of BGA can be fully characterized using ToF-SIMS without any mechanical treatment.