SHARED-BIT-LINE BIT LINE SETUP SCHEME

• US 20130250687A1
• Filed: 03/26/2012
• Published: 09/26/2013
• Est. Priority Date: 03/26/2012
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Chan, Siu Lung
• Granted Patent: US 8,902,659 B2
• Time in Patent Office: Days
• US Class Current: 365/185.17
• CPC Class Codes: G11C 16/04 using variable threshold transistors, e.g. FAMOS
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/24 Bit-line control circuits
• CPC Class Codes: G11C 7/12 Bit line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, equalising circuits, for bit lines

Abstract

Methods for operating a non-volatile storage system utilizing a shared-bit-line NAND architecture are described. A shared-bit-line NAND architecture includes one or more pairs of NAND strings, wherein each pair of the one or more pairs of NAND strings shares a common bit line. In some embodiments, a pair of NAND strings includes an odd NAND string adjacent to an even NAND string. Prior to programming a memory cell associated with the even NAND string, an odd channel associated with the odd NAND string (i.e., the NAND string of the pair that is not selected for programming) is precharged to a bit line inhibit voltage, floated, and then boosted to a second voltage greater than the bit line inhibit voltage as an even channel associated with the even NAND string is precharged. Subsequently, the odd channel may be boosted (e.g., via self-boosting) prior to programming the memory cell.

Claims

1. A non-volatile storage system, comprising:

a first NAND string in communication with a shared bit line, the first NAND string includes a first channel;

a second NAND string in communication with the shared bit line, the second NAND string includes a second channel; and

one or more managing circuits in communication with the first NAND string and the second NAND string, the one or more managing circuits precharge the first channel to a first voltage at a first point in time, the precharging of the first channel boosts the second channel to a first boosted voltage less than the first voltage, the one or more managing circuits precharge the second channel to the first voltage at a second point in time subsequent to the first point in time, the precharging of the second channel boosts the first channel to a second voltage greater than the first voltage, the one or more managing circuits set the shared bit line to a programming voltage at a third point in time subsequent to the second point in time.

2. The non-volatile storage system of claim 1, wherein:

the second NAND string is adjacent to the first NAND string.

3. The non-volatile storage system of claim 1, wherein:

the one or more managing circuits apply a programming voltage to a selected word line at a fourth point in time subsequent to the third point in time.

4. The non-volatile storage system of claim 1, wherein:

the one or more managing circuits bias the shared bit line to the first voltage at the first point in time and bias the shared bit line to the first voltage the second point in time.

5. The non-volatile storage system of claim 1, wherein:

the first voltage comprises a bit line inhibit voltage.

6. The non-volatile storage system of claim 1, wherein:

the one or more managing circuits apply a self-boosted program inhibit scheme to the first NAND string and the second NAND string at a fourth point in time subsequent to the third point in time.

7. The non-volatile storage system of claim 1, wherein:

the one or more managing circuits precharge the first channel to the first voltage at the first point in time by applying a bit line inhibit voltage to the shared bit line.

8. The non-volatile storage system of claim 7, wherein:

the one or more managing circuits precharge the second channel to the first voltage at the second point in time by applying the bit line inhibit voltage to the shared bit line.

9. The non-volatile storage system of claim 1, wherein:

the first NAND string includes a first drain-side select gate in communication with a first select line; and

the second NAND string includes a second drain-side select gate in communication with a second select line different from the first select line.

10. The non-volatile storage system of claim 9, further comprising:

a third NAND string including a third drain-side select gate in communication with the first select line, the third NAND string is adjacent to the second NAND string; and

a fourth NAND string including a fourth drain-side select gate in communication with the second select line, the fourth NAND string is adjacent to the third NAND string.

11. The non-volatile storage system of claim 9, further comprising:

a third NAND string including a third drain-side select gate in communication with the second select line, the third NAND string is adjacent to the second NAND string; and

a fourth NAND string including a fourth drain-side select gate in communication with the first select line, the fourth NAND string is adjacent to the third NAND string.

12. The non-volatile storage system of claim 1, wherein:

the one or more managing circuits increase the programming voltage applied to the shared bit line at a fourth point in time subsequent to the third point in time.

13. A method for operating a non-volatile storage system, comprising:

applying a first voltage to a first channel associated with a first NAND string;

applying a second voltage to a second channel associated with a second NAND string subsequent to the applying a first voltage, the second NAND string is adjacent to the first NAND string, the second NAND string and the first NAND string share a common bit line, the applying a first voltage boosts the second channel to a first boosted voltage less than the first voltage, the applying a second voltage boosts the first channel to a second boosted voltage greater than the first voltage;

setting the common bit line to a programming voltage subsequent to the applying a second voltage;

boosting the first NAND string and the second NAND string subsequent to the setting the common bit line; and

programming a storage element of the second NAND string subsequent to the boosting the first NAND string and the second NAND string.

14. The method of claim 13, wherein:

the first voltage comprises a bit line inhibit voltage.

15. The method of claim 13, wherein:

the setting the common bit line to a programming voltage includes biasing the common bit line substantially close to ground; and

the boosting the first NAND string and the second NAND string includes applying a self-boosted program inhibit scheme to the first NAND string and the second NAND string.

16. The method of claim 13, wherein:

the applying a first voltage includes applying a bit line inhibit voltage to the common bit line.

17. The method of claim 13, wherein:

the applying a second voltage includes applying a bit line inhibit voltage to the common bit line.

18. A non-volatile storage system, comprising:

a first bit line;

a plurality of word lines;

a first selection line;

a second selection line;

a first NAND string in communication with the first bit line, the first NAND string includes a first plurality of non-volatile storage elements and a first selection gate, the first NAND string includes a first channel; and

a second NAND string in communication with the first bit line, the second NAND string includes a second plurality of non-volatile storage elements and a second selection gate, the second NAND string includes a second channel, the plurality of word lines are in communication with the first NAND string and the second NAND string, the first selection line is connected to the first selection gate, the second selection line is connected to the second selection gate, the first channel is set to a first voltage at a first point in time, the second channel is set to the first voltage at a second point in time subsequent to the first point in time, the setting of the second channel to the first voltage boosts the first channel to a second voltage greater than the first voltage, the first bit line is biased to a bit line programming voltage at a third point in time subsequent to the second point in time.

19. The non-volatile storage system of claim 18, wherein:

the second NAND string is adjacent to the first NAND string.

20. The non-volatile storage system of claim 19, wherein:

the first voltage comprises a bit line inhibit voltage.