US Patent 10950786 Layer cost scalable 3D phase change cross-point memory

A 3D memory includes a plurality of first access line levels, a plurality of second access line levels and a plurality of memory cell levels, the memory cell levels being disposed between corresponding first access line levels and second access line levels. The first access line levels include a plurality of first access lines extending in a first direction, and a plurality of remnants of a first sacrificial material disposed between the first access lines. The second access line levels include a plurality of second access lines extending in a second direction and a plurality of remnants of a second sacrificial material disposed between the second access lines. The memory cell levels include an array of memory pillars disposed in the cross-points between the first access lines and the second access lines in adjacent first and second access line levels.