Low stress oxide/nitride passivation topography and influence on electrical devices

A new low-stress oxide/nitride sandwich passivation using layers of plasma-enhanced chemical vapor deposition (PECVD) TEOS and PECVD Si _xN_yH_z that achieves high device lifetimes is presented. A nonplanarized low-stress sandwich as well as a planarized one are investigated. The planarization includes deposition and in-situ etching of the TEOS-based PECVD oxide. Scanning electron microscopy (SEM) analysis of narrow metal 2 spaces and via holes show a conformal oxide/nitride deposition and local planarization of the oxide without voids, respectively. In the case of the nonplanarized passivation variation, as compared to the passivation sandwich with high stress, the lifetimes of three different NMOS devices are increased by a factor of 3-4