Side wall bit line structures
View Patent ↗Methods for reducing leakage currents through unselected memory cells of a memory array during a memory operation are described. In some cases, the leakage currents through the unselected memory cells of the memory array may be reduced by setting an adjustable resistance bit line structure connected to the unselected memory cells into a non-conducting state. The adjustable resistance bit line structure may comprise a bit line structure in which the resistance of an intrinsic (or near intrinsic) polysilicon portion of the bit line structure may be adjusted via an application of a voltage to a select gate portion of the bit line structure that is not directly connected to the intrinsic polysilicon portion. The intrinsic polysilicon portion may be set into a conducting state or a non-conducting state based on the voltage applied to the select gate portion.
1. A non-volatile memory, comprising:
a select gate pillar;
an adjustable resistance local bit line pillar;
a dielectric region arranged between the select gate pillar and the adjustable resistance local bit line pillar;
a first word line; and
a first portion of a memory element layer arranged between the adjustable resistance local bit line pillar and the first word line, the adjustable resistance local bit line pillar comprises one of undoped polysilicon or undoped silicon germanium, the memory element layer comprises a ReRAM material, the dielectric layer comprises one of silicon dioxide or silicon nitride.
2. The non-volatile memory of claim 1 , wherein:
the dielectric region is arranged between the select gate pillar and the adjustable resistance local bit line pillar in a first direction; and
the first portion of the memory element layer is arranged between the adjustable resistance local bit line pillar and the first word line in a second direction substantially orthogonal to the first direction.
3. The non-volatile memory of claim 1 , wherein:
a resistance of the adjustable resistance local bit line pillar is set based on a first voltage applied to the select gate pillar.
4. The non-volatile memory of claim 1 , wherein:
the adjustable resistance local bit line pillar is set into a conducting state based on a first voltage applied to the select gate pillar.
5. The non-volatile memory of claim 1 , further comprising:
a second word line, a second portion of the memory element layer is arranged between the adjustable resistance local bit line pillar and the second word line.
6. The non-volatile memory of claim 1 , wherein:
the adjustable resistance local bit line pillar comprises a substantially rectangular pillar.
7. The non-volatile memory of claim 1 , wherein:
the adjustable resistance local bit line pillar is connected to a global bit line via an integrated resistor arranged between the adjustable resistance local bit line pillar and the global bit line.
8. The non-volatile memory of claim 1 , wherein:
the adjustable resistance local bit line pillar is connected to a global bit line, the global bit line is positioned above the first word line.
9. The non-volatile memory of claim 1 , wherein:
a layer of N+ polysilicon is arranged above the adjustable resistance local bit line pillar, the layer of N+ polysilicon connects a global bit line to the adjustable resistance local bit line pillar.
10. The non-volatile memory of claim 1 , wherein:
a thin-film transistor connects a select gate line to the select gate pillar.
11. The non-volatile memory of claim 1 , further comprising:
a second select gate pillar, the adjustable resistance local bit line pillar is positioned between the select gate pillar and the second select gate pillar.
12. A non-volatile memory, comprising:
a select gate;
a layer of undoped polysilicon;
a dielectric layer arranged between the select gate and the layer of undoped polysilicon;
a first word line; and
a first memory element arranged between the layer of undoped polysilicon and the first word line, the layer of undoped polysilicon is connected to a global bit line, a resistance of the layer of undoped polysilicon between the first memory element and the global bit line is set based on a first voltage applied to the select gate.
13. The non-volatile memory of claim 12 , wherein:
the dielectric layer is arranged between the select gate and the layer of undoped polysilicon in a first direction; and
the first memory element is arranged between the layer of undoped polysilicon and the first word line in a second direction substantially orthogonal to the first direction.
14. The non-volatile memory of claim 12 , wherein:
the layer of undoped polysilicon is set into a conducting state based on the first voltage applied to the select gate.
15. The non-volatile memory of claim 12 , wherein:
the first memory element includes a ReRAM material; and
the dielectric layer includes silicon dioxide.
16. The non-volatile memory of claim 12 , wherein:
the select gate comprises a first substantially rectangular pillar; and
the layer of undoped polysilicon comprises a second substantially rectangular pillar.
17. The non-volatile memory of claim 12 , further comprising:
a second word line, a second memory element is arranged between the layer of undoped polysilicon and the second word line.
18. A non-volatile memory, comprising:
a select gate pillar;
an undoped polysilicon pillar;
a dielectric region arranged between the select gate pillar and the undoped polysilicon pillar;
a first word line; and
a first memory element arranged between the undoped polysilicon pillar and the first word line, the dielectric region is arranged between the select gate pillar and the undoped polysilicon pillar in a first direction, the first memory element is arranged between the undoped polysilicon pillar and the first word line in a second direction substantially orthogonal to the first direction, the undoped polysilicon pillar is set into a conducting state in response to a first voltage applied to the select gate pillar.