Method for using two data busses for memory array block selection
Circuits and methods are described for decoding exemplary memory arrays of programmable and, in some embodiments, re-writable passive element memory cells, which are particularly useful for extremely dense three-dimensional memory arrays having more than one memory plane. In addition, circuits and methods are described for selecting one or more array blocks of such a memory array, for selecting one or more word lines and bit lines within selected array blocks, for conveying data information to and from selected memory cells within selected array blocks, and for conveying unselected bias conditions to unselected array blocks.
1. A method useful for a passive element memory cell array including a first plurality of array blocks, each array block comprising a respective plurality of memory cells, each memory cell coupled to an associated word line and bit line, each respective plurality of memory cells generally bounded by circuits, structures, or gaps which break the contiguous, repetitive pattern of word lines and bit lines and their associated memory cells, said method comprising:
simultaneously selecting, in a first mode of operation, a word line in a first array block within a first group of said first plurality of array blocks, and a word line in a second array block within a second group of said first plurality of array blocks; and
simultaneously coupling, in the first mode of operation, one or more selected bit lines in the first array block to corresponding lines of a first data bus that generally spans the first plurality of array blocks, and one or more selected bit lines in the second array block to corresponding lines of a second data bus that generally spans the first plurality of array blocks.
2. The method of claim 1 further comprising:
coupling said one or more selected bit lines in the respective first and second array blocks to the respective first and second data bus by way of a respective data bus segment associated with each array block.
3. The method of claim 1 wherein the first and second data busses are disposed on opposite sides of each array block of the first plurality of array blocks.
4. The method of claim 1 wherein:
the first group of array blocks comprises odd-numbered array blocks; and
the second group of array blocks comprises even-numbered array blocks.
5. The method of claim 4 wherein the simultaneously selected first and second array blocks are adjacent blocks.
6. The method of claim 5 wherein word lines of one array block are shared with word lines of an adjacent array block, each such word line being coupled in a gap between the adjacent array blocks to a respective word line driver.
7. The method of claim 6 wherein:
the respective selected word line in the first and second array blocks comprise two logical word lines, each respectively coupled in respective gaps between adjacent array blocks on the outer sides of the adjacent first and second array blocks to respective word line drivers.
8. The method of claim 6 wherein:
the respective selected word line in the first and second array blocks comprise a single logical word line coupled in a gap between the adjacent first and second array blocks to a respective word line driver.
9. The method of claim 5 wherein the first and second data busses are disposed on opposite sides of each array block of the first plurality of array blocks.
10. The method of claim 4 further comprising:
simultaneously coupling, at other times in the first mode of operation, one or more selected bit lines in the first array block to corresponding lines of the second data bus, and one or more selected bit lines in the second array block to corresponding lines of the first data bus.
11. The method of claim 10 wherein the first and second data busses are disposed on opposite sides of each array block.
12. The method of claim 10 wherein:
the memory array comprises a three-dimensional memory array having bit lines on more than one bit line layer; and
the one or more selected bit lines in a respective first or second array block that are simultaneously coupled to corresponding lines of a respective first or second data bus comprise one or more bit lines on a first bit line layer and one or more bit lines on a second bit line layer.
13. The method of claim 12 wherein:
the word lines in each array block each comprises a word line segment on each of more than one word line layer.
14. The method of claim 10 wherein:
the memory array comprises two-terminal memory cells, each comprising a reversible resistor element and a diode; and
wherein the method further comprises, in the first mode of operation, programming selected memory cells using reverse bias from a lower to a higher resistance state.
15. The method of claim 14 further comprising, in the first mode of operation, biasing unselected memory cells in both selected and unselected memory blocks with no voltage thereacross, to reduce leakage current power dissipation in the memory array.
16. The method of claim 10 wherein:
word lines of one array block are shared with word lines of an adjacent array block, each such word line being coupled in a gap between the adjacent array blocks to a respective word line driver; and
the word lines in each array block each comprises a word line segment on each of more than one word line layer.
17. The method of claim 16 wherein:
the first and second data busses are disposed on opposite sides of each array block;
the memory array comprises bit lines on more than one bit line layer;
the one or more selected bit lines in a respective first or second array block that are simultaneously coupled to corresponding lines of a respective first or second data bus comprise one or more bit lines on a first bit line layer and one or more bit lines on a second bit line layer; and
the respective selected word line in the first and second array blocks comprise a single logical word line coupled to a respective word line driver.
18. The method of claim 17 wherein:
the memory array comprises two-terminal memory cells, each comprising a transition metal oxide and a diode; and
wherein the method, in the first mode of operation, further comprises:
programming one or more selected memory cells using reverse bias from a lower to a higher resistance state;
biasing unselected memory cells in both selected and unselected memory blocks with no voltage thereacross.
19. A method for making a memory product, said method comprising:
forming a memory array including a first plurality of array blocks, each array block comprising a respective plurality of memory cells, each memory cell coupled to an associated word line and bit line, each respective plurality of memory cells generally bounded by circuits, structures, or gaps which break the contiguous, repetitive pattern of word lines and bit lines and their associated memory cells;
forming a first data bus generally spanning the first plurality of array blocks, each of a first group of the first plurality of array blocks associated with the first data bus;
forming a second data bus generally spanning the first plurality of array blocks, each of a second group of the first plurality of array blocks associated with the second data bus;
forming a row selection circuit configured, in a first mode of operation, to simultaneously select a word line in a first array block within the first group and a word line in a second array block within the second group; and
forming a column selection circuit configured, in the first mode of operation, to simultaneously couple one or more selected bit lines in the first array block to corresponding lines of the first data bus, and one or more selected bit lines in the second array block to corresponding lines of the second data bus.
20. The method of claim 1 further comprising:
selecting, in a second mode of operation, a word line in the first array block within the first group of array blocks; and
simultaneously coupling, in the second mode of operation, one or more selected bit lines in the first array block to corresponding lines of the first data bus, and one or more other selected bit lines in the first array block to corresponding lines of the second data bus.