Non-volatile storage using current sensing with biasing of source and P-Well
View Patent ↗A non-volatile storage device in which current sensing is performed for a non-volatile storage element. A voltage is applied to a selected word line of the first non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages are regulated at respective positive DC levels to avoid a ground bounce, or voltage fluctuation, which would occur if the source voltage at least was regulated at a ground voltage. A programming condition of the non-volatile storage element is determined by sensing a current in a NAND string of the non-volatile storage element. The sensing can occur quickly since there is no delay in waiting for the ground bounce to settle.
1. A non-volatile storage system, comprising:
a set of non-volatile storage elements including at least a first non-volatile storage element; and
one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits: (a) apply at least a first voltage to a selected word line which is associated with the at least a first non-volatile storage element, (b) regulate a source voltage at a positive DC level for a source which is associated with the at least a first non-volatile storage element during at least a portion of a time in which the at least a first voltage is applied, and (c) determine whether the at least a first non-volatile storage element is in a conductive or non-conductive state using current sensing while applying the at least a first voltage and regulating the source voltage.
2. The non-volatile storage system of claim 1 , wherein:
the one or more control circuits regulate a p-well voltage at a positive DC level for a p-well which is associated with the at least a first non-volatile storage element during at least a portion of a time in which the at least a first voltage is applied.
3. The non-volatile storage system of claim 2 , wherein:
the source and p-well voltages are regulated at different DC levels.
4. The non-volatile storage system of claim 2 , wherein:
the source and p-well voltages are regulated at a common DC level.
5. The non-volatile storage system of claim 1 , wherein:
the one or more control circuits ground a voltage of a p-well which is associated with the at least a first non-volatile storage element during at least a portion of a time in which the at least a first voltage is applied.
6. The non-volatile storage system of claim 1 , wherein:
the at least a first non-volatile storage element has a negative threshold voltage.
7. The non-volatile storage system of claim 1 , wherein:
the at least a first non-volatile storage element is in a NAND string and the source voltage is applied to a source side of the NAND string.
8. The non-volatile storage system of claim 1 , wherein:
the one or more control circuits use the current sensing by determining a voltage drop which is proportional to a fixed current which flows through the at least a first non-volatile storage element and sinks into the source when the at least a first non-volatile storage element is in the conductive state.
9. The non-volatile storage system of claim 1 , wherein:
the selected word line is associated with non-volatile storage elements in a plurality of adjacent NAND strings;
the source is associated with each of the non-volatile storage elements; and
the one or more control circuits determine, in concurrent sensing operations, whether each of the non-volatile storage elements is in the conductive or non-conductive state using current sensing while applying the at least a first voltage and during the regulating.
10. The non-volatile storage system of claim 1 , wherein:
during the current sensing, a fixed current flows through the at least a first non-volatile storage element and sinks into the source when the at least a first non-volatile storage element is in the conductive state.
11. A non-volatile storage system, comprising:
a set of non-volatile storage elements including at least a first non-volatile storage element; and
one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits: (a) apply at least a first voltage to a selected word line of the at least a first non-volatile storage element, (b) regulate source and p-well voltages at respective positive DC levels for a source and p-well, respectively, which are associated with the at least a first non-volatile storage element during at least a portion of a time in which the at least a first voltage is applied, and (c) sense a programming condition of the at least a first non-volatile storage element relative to a compare point using current sensing, while applying the at least a first voltage and regulating the source and p-well voltages.
12. The non-volatile storage system of claim 11 , wherein:
the one or more control circuits regulate the source and p-well voltages at different positive DC levels.
13. The non-volatile storage system of claim 11 , wherein:
the one or more control circuits regulate the source and p-well voltages at a common positive DC level.
14. The non-volatile storage system of claim 11 , wherein:
the programming condition is defined with respect to a negative threshold voltage, and the at least a first voltage is a positive voltage.
15. The non-volatile storage system of claim 11 , wherein:
the programming condition is defined with respect to a positive threshold voltage.
16. A non-volatile storage system, comprising:
a set of non-volatile storage elements including at least a first non-volatile storage element; and
one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits: (a) provide a potential of a drain associated with the at least a first non-volatile storage element above a potential of a source associated with the at least a first non-volatile storage element, (b) apply at least a first voltage to a selected word line of the at least a first non-volatile storage element, (c) regulate source and p-well voltages at respective positive DC levels for a source and p-well, respectively, which are associated with the at least a first non-volatile storage element during at least a portion of a time in which the at least a first voltage is applied, (d) while applying the at least first voltage, and regulating the source and p-well voltages, perform current sensing with respect to a level of a current which flows through the at least a first non-volatile storage element and sinks into the source, and (e) determine a programming condition of the at least a first non-volatile storage element according to the current sensing.
17. The non-volatile storage system of claim 16 , wherein:
the one or more control circuits regulate the source and p-well voltages at different positive DC levels.
18. The non-volatile storage system of claim 16 , wherein:
the one or more control circuits regulate the source and p-well voltages at a common positive DC level.
19. The non-volatile storage system of claim 16 , wherein:
the programming condition is defined with respect to a negative threshold voltage, and the at least first voltage is a positive voltage.
20. The non-volatile storage system of claim 16 , wherein:
the programming condition is defined with respect to a positive threshold voltage.