A monolithic three dimensional memory array is formed by a method that
includes forming a first memory level above a substrate by i) forming a
plurality of first substantially parallel conductors extending in a first
direction, ii) forming first pillars above the first conductors, each
first pillar comprising a first conductive layer or layerstack above a
vertically oriented diode, the first pillars formed in a single
photolithography step, iii) depositing a first dielectric layer above the
first pillars, and iv) etching a plurality of substantially parallel
first trenches in the first dielectric layer, the first trenches
extending in a second direction, wherein, after the etching step, the
lowest point in the trenches is above the lowest point of the first
conductive layer or layerstack, wherein the first conductive layer or
layerstack does not comprise a resistivity-switching metal oxide or
nitride. The method also includes monolithically forming a second memory
level above the first memory level. Other aspects are also described.