Failure Analysis on Superluminescent Diode

A super luminescent diode (SLED or SLD) is an edge-emitting semiconductor light source that relies on super luminescence. SLDs are ideal for use in Optical Coherence Tomography (OCT) Imaging Systems. In this paper, we reported the failure analysis plan and method for rejections from the SLD lifetime test. The failure modes for the SLD reliability test have been defined. A failure analysis flowchart was designed to identify the failure location, from the package to the chip. A scanning optical microscope (SOM), a liquid nitrogen-cooled InGasAs emission microscope, and a liquid nitrogen-cooled thermal emission microscope were used for fault isolation. An optical microscope (OM) and a scanning electron microscope (SEM) were employed to inspect the hotspot locations. Subsequently, a physical analysis was conducted on the failing location, and the failure mechanism was studied. Planar and cross-section TEM laminae were prepared using a dual-beam FIB. TEM EDX analysis was conducted on the cross-section TEM sample. The EDX analysis reveals that there is no obvious difference in element distribution, suggesting that no thermal diffusion occurred and the failure was solely due to material degradation.