The method 13, wherein a number of {HEAD ~ masking steps} used for forming the crossbar array is independent of a number of metal and insulator layers of {TAIL ~ the crossbar array} 
The method 13 , wherein a number of { HEAD ~ masking steps } used for forming the crossbar array is independent of a number of metal and insulator layers of { TAIL ~ the crossbar array }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL