In the absence of the silicon nitride film on {HEAD ~ the trench sidewalls}, the ambient to be used is preferably any of water vapor, {TAIL ~ oxygen}, nitrogen, hydrogen and N2O or any combination of them 
In the absence of the silicon nitride film on { HEAD ~ the trench sidewalls } , the ambient to be used is preferably any of water vapor , { TAIL ~ oxygen } , nitrogen , hydrogen and N2O or any combination of them
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH