Non-volatile storage with bias for temperature compensation
View Patent ↗A non-volatile storage system in which a body bias is applied to a non-volatile storage system to compensate for temperature-dependent variations in threshold voltage, sub-threshold slope, depletion layer width and/or 1/f noise. A desired bias level is set based on a temperature-dependent reference signal. In one approach, a level of the biasing can decrease as temperature increases. The body bias can be applied by applying a voltage to a p-well and n-well of a substrate, applying a voltage to the p-well while grounding the n-well, or grounding the body and applying a voltage to the source and/or drain of a set of non-volatile storage elements. Further, temperature-independent and/or temperature-dependent voltages can be applied to selected and unselected word lines in the non-volatile storage system during program, read or verify operations. The temperature-dependent voltages can vary based on different temperature coefficients.
1. A non-volatile storage system, comprising:
a set of non-volatile storage elements formed, at least in part, on a substrate;
a set of word lines in communication with the set of non-volatile storage elements, at least one non-volatile storage element of the set of non-volatile storage elements is in communication with a selected word line of the set of word lines; and
one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits provide temperature-dependent biasing of the substrate and during the biasing:
perform an operation on the at least one non-volatile storage element;
apply a temperature-independent voltage to at least one of a source side and a drain side of the set of non-volatile storage elements; and
apply a temperature-dependent read or verify voltage to a selected word line of one or more non-volatile storage elements undergoing read or verify operations;
wherein the temperature-dependent read or verify voltage varies with temperature according to a first temperature coefficient, and the temperature-dependent biasing of the substrate varies with temperature according to a second temperature coefficient which differs from the first temperature coefficient.
2. The non-volatile storage system of claim 1 , wherein:
the operation involves applying temperature-independent voltages to unselected word lines of the set of word lines during the biasing.
3. The non-volatile storage system of claim 1 , wherein:
a level of the biasing decreases as temperature increases.
4. The non-volatile storage system of claim 1 , wherein:
the biasing is set to vary with temperature to compensate at least one temperature-varying characteristic of non-volatile storage elements of the set of non-volatile storage elements.
5. The non-volatile storage system of claim 4 , wherein:
the at least one temperature-varying characteristic comprises threshold voltage.
6. The non-volatile storage system of claim 4 , wherein:
the at least one temperature-varying characteristic comprises a sub-threshold slope.
7. The non-volatile storage system of claim 4 , wherein:
the at least one temperature-varying characteristic comprises depletion layer width.
8. The non-volatile storage system of claim 4 , wherein:
the at least one temperature-varying characteristic comprises 1/f noise.
9. The non-volatile storage system of claim 1 , wherein:
the set of non-volatile storage elements are provided in at least one NAND string which is formed, at least in part, on the substrate.
10. The non-volatile storage system of claim 1 , wherein:
the biasing comprises applying a forward body bias.
11. The non-volatile storage system of claim 1 , wherein:
the biasing comprises applying a reverse body bias.
12. A non-volatile storage system, comprising:
a set of non-volatile storage elements formed, at least in part, on a substrate;
a set of word lines in communication with the set of non-volatile storage elements, at least one non-volatile storage element of the set of non-volatile storage elements is in communication with a selected word line of the set of word lines; and
one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits provide temperature-dependent biasing of the substrate and during the biasing:
perform an operation on the at least one non-volatile storage element;
apply a temperature-independent voltage to at least one of a source side and a drain side of the set of non-volatile storage elements; and
apply temperature-dependent voltages to unselected word lines of the set of word lines;
wherein the temperature-dependent voltages applied to the unselected word lines vary with temperature according to a first temperature coefficient, and the temperature-dependent biasing of the substrate varies with temperature according to a second temperature coefficient which differs from the first temperature coefficient.