Patent ID: 8575715

Claim:
A method of forming a non-volatile storage device, the method comprising: forming a first plurality of conductors that extend in a first direction; forming a second plurality of conductors that extend in a second direction that is substantially perpendicular to the first direction, one of the first conductors and one of the second conductors define a pair of conductors; forming a plurality of memory cells, each of the memory cells residing between one pair of the pairs of conductors, the forming the memory cells including: forming a reversible resistivity-switching element; and forming a punch-through diode having a graded doping profile in series with the reversible resistivity-switching element, the forming a punch-through diode having a graded doping profile in series with the reversible resistivity-switching element includes: forming a first heavily doped semiconductor region having a graded doping profile; forming a region of a semiconductor material; and forming a second heavily doped semiconductor region having a graded doping profile, the region of a semiconductor material between the first and second heavily doped semiconductor regions.