The method comprises steps of forming a first oxide layer over {TAIL ~ the substrate} and forming a nitride layer on {HEAD ~ the first oxide layer} 
The method comprises steps of forming a first oxide layer over { TAIL ~ the substrate } and forming a nitride layer on { HEAD ~ the first oxide layer }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD