Thermal annealing effects on the stress stability in silicon dioxide films grown by plasma-enhanced chemical vapor deposition

Abstract

The stress stability in plasma-enhanced chemical vapor deposition (PECVD) silicon dioxide (SiO2) films is a key factor of device performance. In this study, the PECVD SiO2 films are annealed at 400–1000 °C in a nitrogen (N2) or oxygen (O2) ambience for 2 h. The influences of annealing parameters on the stress state and stress stability in PECVD SiO2 films are investigated. The bonding nature and surface morphology of the films are also studied to analyze the physical mechanism involved. It is demonstrated that the stress stability is first deteriorated and then improved with increasing annealing temperature. In addition, O2 ambience is more appropriate to improve stress stability than N2, and the stress in PECVD SiO2 film can be stabilized when it is annealed at 1000 °C in O2 ambience. These results should be able to provide important insights into the design of device fabrication processes.