Three dimensional non-volatile storage with dual gated vertical select devices
A three-dimensional array adapted for memory elements that reversibly change a level of electrical conductance in response to a voltage difference being applied across them. Memory elements are formed across a plurality of planes positioned different distances above a semiconductor substrate. Bit lines to which the memory elements of all planes are connected are oriented vertically from the substrate and through the plurality of planes.
1. A non-volatile storage system, comprising:
a substrate;
a monolithic three dimensional memory array of memory cells positioned above and not in the substrate;
word lines connected to the memory cells;
a plurality of word line drivers in the substrate and in communication with the word lines;
a plurality of bit line drivers in the substrate;
a plurality of global bit lines connected to the bit line drivers;
a plurality of vertically oriented bit lines above and not in the substrate, the vertically oriented bit lines are connected to the memory cells;
a plurality of vertically oriented select devices that are above, but not in the substrate, and that are connected to the vertically oriented bit lines and the global bit lines; and
a plurality of select lines connected to the select devices, each select device is positioned between two of the select lines so that each select device can be controlled by either of two neighboring select lines.
2. The non-volatile storage system of claim 1 , wherein:
a memory cell is accessed by selecting a vertically oriented select device directly below a particular vertically oriented bit line connected to the memory cell using the select line that is on an opposite side of the particular vertically oriented bit line than the memory cell.
3. The non-volatile storage system of claim 1 , further comprising:
vertically oriented layers of non-volatile switching material on each of two sides of the vertically oriented bit lines such that memory cells are formed on the two sides of the vertically oriented bit lines, the vertically oriented select devices are positioned directly below the vertically oriented bit lines, a particular memory cell on a first of the two sides of a particular vertically oriented bit line is accessed by selecting a vertically oriented select device directly below the particular vertically oriented bit line using a select line that is on a second of the two sides of the particular vertically oriented bit line.
4. The non-volatile storage system of claim 1 , wherein:
a memory cell is accessed by selecting an associated vertically oriented select device using the select lines on both sides of the respective vertically oriented bit line.
5. The non-volatile storage system of claim 1 , wherein:
each select line is positioned between two vertically oriented select devices so that each select line can drive either vertically oriented select device that it is between.
6. The non-volatile storage system of claim 1 , wherein:
for a particular vertically oriented select device, both of the two neighboring select lines can serve as a gate signal so that the particular vertically oriented select device is double gated.
7. The non-volatile storage system of claim 1 , wherein:
a particular vertically oriented bit line is connectable to one of the global bit lines by two of the select lines.
8. The non-volatile storage system of claim 1 , wherein:
the vertically oriented select devices are active thin film transistors with vertically oriented channels.
9. The non-volatile storage system of claim 1 , wherein:
the plurality of vertically oriented select devices and the plurality of select lines are positioned in a select layer that is below the monolithic three dimensional array of memory cells and above a metal layer, the metal layer includes the global word lines and is positioned on top of the substrate.
10. A non-volatile storage system, comprising:
a substrate;
a monolithic three dimensional memory array of memory cells positioned above and not in the substrate;
word lines connected to the memory cells;
a plurality of word line drivers in the substrate and in communication with the word lines;
a plurality of bit line drivers in the substrate;
a plurality of global bit lines connected to the bit line drivers;
a plurality of vertically oriented bit lines above and not in the substrate;
a plurality of vertically oriented select devices that are above, but not in the substrate and that are connected to the vertically oriented bit lines and the global bit lines; and
a plurality of select lines connected to gates of the vertically oriented select devices, each select line is positioned between two select devices so that each select line can drive either select devices that it is between.
11. The non-volatile storage system of claim 10 , wherein:
for a particular vertically oriented select device, both of two neighboring select lines can serve as the gate signal so that the particular vertically oriented select device is double gated.
12. The non-volatile storage system of claim 10 , wherein:
a memory cell is accessed by selecting an associated select device using a select line that is on an opposite side of a respective vertically oriented bit line than the memory cell.
13. The non-volatile storage system of claim 10 , further comprising:
vertically oriented layers of non-volatile switching material on each of two sides of the vertically oriented bit lines such that memory cells are formed on the two sides of the vertically oriented bit lines, the vertically oriented select devices are positioned directly below the vertically oriented bit lines, a particular memory cell on a first of the two sides of a particular vertically oriented bit line is accessed by selecting a select device directly below the particular vertically oriented bit line using a select line that is on a second of the two sides of the particular vertically oriented bit line.
14. A non-volatile storage system, comprising:
a substrate layer;
a select layer positioned above and not in the substrate layer;
a memory layer positioned above and not in the substrate layer, the memory layer includes:
a monolithic three dimensional array of memory elements,
word lines connected to the memory elements, and
vertically oriented bit lines connected to the memory elements, the memory elements in combination with the vertically oriented bit lines and the word lines form a continuous mesh, the select layer includes select lines and vertically oriented select devices that are connected to the vertically oriented bit lines and the select lines, each vertically oriented select device is positioned between two of the select lines so that each select device can be controlled by either of two neighboring select lines.
15. The non-volatile storage system of claim 14 , wherein:
a memory element is accessed by selecting an associated select device using the select line that is on an opposite side of a respective vertically oriented bit line than the memory cell.
16. The non-volatile storage system of claim 14 , further comprising:
vertically oriented layers of non-volatile switching material on each of two sides of the vertically oriented bit lines such that memory elements are formed on the two sides of the vertically oriented bit lines, the vertically oriented select devices are positioned directly below the vertically oriented bit lines, a particular memory element on a first of the two sides of a particular vertically oriented bit line is accessed by selecting a select device directly below the particular vertically oriented bit line using a select line that is on a second of the two sides of the particular vertically oriented bit line.
17. The non-volatile storage system of claim 14 , wherein:
a memory element is accessed by selecting an associated select device using the select lines on both sides of the respective vertically oriented bit line.
18. The non-volatile storage system of claim 14 , wherein:
each select line is positioned between two select devices so that each select line can drive either select device that it is between.
19. The non-volatile storage system of claim 14 , wherein:
for a particular vertically oriented select device, both of the two neighboring select lines can serve as a gate signal so that the vertically oriented select device is double gated.