Investigation and Improvement of Fast Temperature-Cycle Reliability for DMOS-Related Conductor Path Design

During operation double-diffused-MOS (DMOS) transistors are subjected cyclically to severe temperature pulses. The resultant thermo-mechanical stress causes a viscoplastic deformation of the metallization. This increases the local stress on the interlayer dielectric (ILD) beyond a critical limit and results in ILD cracking. The DMOS fails due to electric short-circuits, that are caused by extruding aluminum. Due to its relevance for the DMOS design, the influence of the conductor line width is studied with a special test structure (Nguyen et al., 2002). From the observed failure evolution an effective method to improve fast temperature-cycle reliability is derived.