CUBIC MEMORY ARRAY, MEMORY CIRCUIT FORMING METHOD, OPERATING METHOD OF CUBIC MEMORY ARRAY AND RETENTION CIRCUIT

摘要

PURPOSE: A cubic memory array is provided to increase the density of a semiconductor memory device and to increase the amount of control elements by using diagonal select lines. CONSTITUTION: A different set of word-lines(20a-20d) is provided at each level of the cubic memory array for the memory cells(22) of that level. The connection between each memory cell(22) and one of the bit-lines(19a-f, 21a-i) is made through one of the conductive pillars(18). A set of bit-line(19a-f, 21a-i) is not disposed at each level of the cubic array. Rather, the bit-lines(19a-f, 21a-i) are preferably disposed outside the array of memory cells and connected to the memory cells(22) through pillars(18) that extend through the array of memory cells. The pillars(18) extend through the layers of memory cells(22) and normal to a base substrate on which the cubic memory array is formed. Thus, each memory cell(22) is connected to one of the pillars(18). A number of memory cells(22) at different levels in the cubic array share, and are connected to, each one of the pillars(18). The pillars(18) then provide the connection between each memory cell(22) and one of the bit-lines(19a-f, 21a-i).