What is the current PECVD recipe for Silicon Oxy Nitride and are there refractive index tuning curves available?
There are currently two silicon oxynitride recipes available on the PECVD. The fast recipe is relatively new and hasn’t been thoroughly tested, but it does have a higher index of 1.802. The slow recipe is the original recipe from Oxford and has an index of 1.747. We’ve gathered some data for tuning the refractive index on that recipe, though that was more focused on tuning the index by small increments of hundredths or thousandths by varying the NH3 flow, N2O flow, chamber pressure or RF power. Typically to get larger variations of the refractive index you’d want to increase or decrease the amount of silicon in the film, so adjusting the SiH4 flow should achieve that.
Here’s some tuning curves for the slow silicon oxynitride recipe:
