Resistive memory architectures with multiple memory cells per access device
View Patent ↗A resistive memory structure, for example, phase change memory structure, includes one access device and two or more resistive memory cells. Each memory cell is coupled to a rectifying device to prevent parallel leak current from flowing through non-selected memory cells. In an array of resistive memory bit structures, resistive memory cells from different memory bit structures are stacked and share rectifying devices.
1. A resistive memory structure, comprising:
a plurality of stacked resistive memory cells, each stack including a first and a second resistive memory cell;
a common electrode positioned between the first and second resistive memory cells of a stack and electrically coupling the first and second resistive memory cells to a cell select line; and
a plurality of access devices, each access device electrically coupled to a first resistive memory cell of a first stack via a first rectifying device and to a second resistive memory of a second stack via a second rectifying device.
2. The resistive memory structure of claim 1 , wherein the first and second rectifying devices are formed at least partially within the access devices.
3. The resistive memory structure of claim 1 , wherein the first resistive memory cell of the first stack comprises a lower memory cell of the first stack and the second resistive memory cell of the second stack comprises a upper memory cell of the second stack.
4. The resistive memory structure of claim 1 further comprising, a metal material electrically coupling the second resistive memory cell of the second stack to the second rectifying device.
5. A resistive memory structure, comprising:
two pairs of stacked resistive memory cells;
a pair of access devices, each access device being coupled to a respective one of the resistive memory cells in the two pairs of stacked memory cells via a respective rectifying device; and
a common electrode being positioned between the memory cells in each of the two pairs of stacked resistive memory cells and coupling each stacked resistive memory cell to a common cell select line,
wherein the two pairs of stacked resistive memory cells share the common electrode that is positioned between each memory cell in each of the two pairs of stacked resistive memory cells; and
wherein each of the two pairs of stacked resistive memory cells includes an upper memory cell and a lower memory cell, the lower memory cells being closer to a plane that includes the access devices than the upper memory cells.
6. The resistive memory structure of claim 5 , wherein the access devices coupled to the lower memory cells are positioned in an active area aligned with a position of the two pairs of stacked resistive memory cells.
7. The resistive memory structure of claim 5 , wherein the access devices coupled to the upper memory cells are positioned in active areas that are offset from the position of the two pairs of stacked resistive memory cells.
8. The resistive memory structure of claim 7 , wherein the offset active areas are offset in a parallel arrangement with respect to the aligned active area.
9. The resistive memory structure of claim 7 , wherein the offset active areas are offset in a checkerboard with respect to the aligned active area.
10. The resistive memory structure of claim 1 , wherein an access device electrically coupled to the first memory cell of the first stack is positioned in an active area aligned with a position of the first stack.
11. The resistive memory structure of claim 1 , wherein an access device electrically coupled to the second memory cell of the second stack is positioned in an active area that is offset from a position of the second stack.