Reoxidation of a high-nitrogen ultra-thin oxynitride (∼1.3nm), which is formed by thermally nitridizing a chemical silicon oxide with pure ammonia at 800°C and at low pressure, has been studied. The reoxidation is conducted using an alternating nitrous oxide and oxygen gas by rapid thermal oxidation at 1000°C for 60 seconds and 90 seconds, respectively. It is important to find the unusual results of oxidation of oxynitride film in the RTP chamber. A non-uniform thickness of oxynitride was observed after N2O gas ambient annealing. Particularly, the thickness is thinner in the center part of the wafer instead of at the edge of the wafer. It should be noted that O 2 gas does not produce the same results. Any conventional oxidation model based on simple bulk diffusion and/or surface reaction mechanisms simply would not do it. The purpose of this study was to explain that the non-uniformity of N2O gas reoxidation was due to a mechanism combining radial thermally induced stress, exothermic N2O oxidation and depletion of atomic oxygen. This is a fairly new discovery and this report can provide a deeper insight into the behavior of reoxidation of oxynitride film using N2O gas.
|Number of pages||7|
|Journal||International Journal of Electrical Engineering|
|State||Published - 1 May 2006|
- Atomic oxygen
- Thermally induced stress