Studies of ESD-related failure patterns of Agilent oxide VCSELs

摘要

Electrostatic Discharge (ESD) damage is considered to be the leading cause for IC field failures. With increasing integration densities, devices tend to become more and more sensitive to ESD events. This observation holds particularly true for 850nm VCSELs, as the quest for higher modulation frequencies calls for shrinking device dimensions, aperture sizes in particular. This publication is geared towards an understanding of the various factors that lead to ESD-related failures of oxide VCSELs. A broad variety of current VCSEL product lines at Agilent have been investigated in respect to their ESD resistance and related long-term reliability. Intentionally stressed devices have been characterized in terms of their electrical, optical and visual failure patterns as well as the medium time-to-failure. Cross-sectional and plan-view TEM have been employed to localize ESD damage and its propagation. For the first time, emission microscopy has been used to study the electroluminescence pattern of damaged VCSELs at very low currents. The paper will conclude by listing experimental signatures allowing for differentiation between ESD and other failure modes. Based upon these, effective screening methods are proposed.