Optical emission spectrum analyses during pulsed laser deflash of integrated circuit packages

Abstract

Optical emission spectrum analysis during Nd:YAG laser deflash of molding compound for integrated circuits (IC) packaging is investigated. Dependence of spectral line and band intensities for SiO molecules, Si excited atoms and ions on laser fluence is measured to study plasma species evolution. Threshold fluences for the spectral line and band appearance are also estimated. Temporally resolved optical emission spectrum analysis shows that the spectral lines and bands appear and recombine at different delay times after laser irradiation. Mechanism for spectral line generation and recombination is found to be attributed to strong collisions among plasma species. © 1999 Publication Board, Japanese Journal of Applied Physics.