Patent ID: 6908811

Claim:
A method for forming in monolithic form a DRAM-type memory, including the steps of: forming, on a single-crystal semiconductor substrate, parallel strips including a lower insulating layer, a strongly-conductive layer, a single-crystal semiconductor layer, and an upper insulating layer; forming, perpendicularly to the parallel strips, in the upper insulating layer and in at least a portion of the single-crystal semiconductor layer, first and second parallel trenches, each of the first and second parallel trenches being shared by neighboring cells; forming, in each of the first parallel trenches, a first conductive line according to a strip width; forming, in each of the second parallel trenches, a pair of second distinct parallel conductive lines, insulated from layers peripheral to the second parallel trench; filling the first and second parallel trenches with an insulating material; removing the remaining portions of the upper insulating layer; and depositing a conductive layer, wherein the first and second parallel trenches are formed in the upper insulating layer and at least a portion of the single-crystal semiconductor layer so that the first parallel trenches have a minimum width, and the second parallel trenches have a width which is twice that of the first parallel trenches, two neighboring parallel trenches being separated by a minimum interval, each first parallel trench being surrounded with two second parallel trenches and each second parallel trench being surrounded with two first parallel trenches.