Three-dimensional resistive random access memory containing self-aligned memory elements

A monolithic three-dimensional memory device, comprising:

• a plurality of alternating stacks of insulator lines and first electrically conductive lines located over a substrate, wherein each of the insulator lines and the first electrically conductive lines extends along a first horizontal direction, and the alternating stacks are laterally spaced from one another along a second horizontal direction;
• vertically spaced sets of metal oxide lines, each metal oxide line being self-aligned to a sidewall of a respective first electrically conductive line and not physically contacting any other of the metal oxide lines;
• and
• a plurality of second electrically conductive lines extending vertically and contacting one or more vertically spaced sets of metal oxide lines
• wherein each metal oxide line includes:
• a first vertical sidewall contacting a vertical sidewall of a respective one of the first electrically conductive lines, a lower portion of a vertical sidewall of an insulator line overlying the respective one of the first electrically conductive lines, and an upper portion of a vertical sidewall of another insulator line underlying the respective one of the first electrically conductive lines;
• and
• a second vertical sidewall that is parallel to the first vertical sidewall and laterally spaced from the first vertical sidewall;
• wherein each of the plurality of second electrically conductive lines has a lesser width along the second horizontal direction at levels of the first electrically conductive lines than at levels of the insulator lines;
• wherein each of the plurality of second electrically conductive lines has a maximum width along the second horizontal direction at a level of one of the insulator lines, and has a minimum width along the second horizontal direction at a level of one of the first electrically conductive lines;
• and
• wherein each metal oxide line has a first width, and a difference between the maximum width and the minimum width for each of the plurality of second electrically conductive lines is twice the first width of the metal oxide lines.