3D independent double gate flash memory

摘要

A memory device configurable for independent double gate cells, storing multiple bits per cell includes multilayer stacks of conductive strips configured as word lines. Active pillars are disposed between pairs of first and second stacks, each active pillar comprising a vertical channel structure, a charge storage layer and an insulating layer. The insulating layer in a frustum of an active pillar contacts a first arcuate edge of a first conductive strip in a layer of the first stack and a second arcuate edge of a second conductive strip in a same layer of the second stack. A plurality of insulating columns serve, with the active pillars, to divide the stacks of word lines into even and odd lines contacting opposing even and odd sides of each active pillar. The active pillar can be generally elliptical with a major axis parallel with the first and second conductive strips.

主权项

1. A memory device, comprising:
a plurality of word line layers, a word line layer in the plurality including a first word line structure comprising a first landing pad element and a plurality of even word lines extending away from the first landing pad element, and a second word line structure comprising a second landing pad element and a plurality of odd word lines extending away from the second landing pad element and interdigitated with the plurality of even word lines; a plurality of rows of active pillars and insulating pillars extending through the plurality of word line layers, the rows in the plurality disposed between corresponding even word lines and odd word lines, the active pillars in a row in the plurality rows comprising respectively a vertical channel structure, a charge storage layer and an outside insulating layer; the insulating pillars in the row separating the even and odd word lines between the active pillars; and in frustums of the active pillars in the plurality of word line layers, the outside insulating layers of the active pillars contacting a first arcuate edge of an even word line and a second arcuate edge of an odd word line.