MULTI-PASS PROGRAMMING FOR MEMORY WITH REDUCED DATA STORAGE REQUIREMENT

• US 20100061151A1
• Filed: 12/29/2008
• Published: 03/11/2010
• Est. Priority Date: 09/11/2008
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Hemink, Gerrit Jan, Miwa, Toru
• Granted Patent: US 8,130,552 B2
• Time in Patent Office: Days
• US Class Current: 365/185.170
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data
• CPC Class Codes: G11C 2211/5621 Multilevel programming verification

Abstract

Coupling effects between adjacent floating gates in a non-volatile storage device are reduced in a multi-pass programming operation, while reducing program data storage requirements. In one approach, storage elements are programmed in an out of sequence or zigzag word line order. A particular word line is programmed with a coarse program pass, after which another word line is programmed with a fine program pass, after which the particular word line is read. The particular word line is read before another word line is programmed with a coarse program pass which causes coupling interference to storage elements of the particular word line. The read data is subsequently used to perform a fine program pass for the particular word line. This avoids the need to store program data of multiple word lines concurrently, so that storage hardware can be reduced in size along with power consumption.

Claims

1. A method for operating non-volatile storage, comprising:

(a) programming a particular non-volatile storage element to raise its threshold voltage to a first level which is above a first verify level, including verifying that the threshold voltage is above the first verify level, the first verify level is associated with a target data state of the particular non-volatile storage element;

(b) reading the particular non-volatile storage element after the programming to determine that the threshold voltage has been raised above the first verify level;

(c) responsive to the reading, further programming the particular non-volatile storage element to raise its threshold voltage from the first level to a second level which is above a second verify level associated with the target data state.

2. The method of claim 1, wherein:

the reading determines the target data state.

3. The method of claim 1, wherein the particular non-volatile storage element is series-connected to other non-volatile storage elements in a set of non-volatile storage elements, the method further comprising:

programming at least one of the other non-volatile storage elements after step (a) and before step (c).

4. The method of claim 3, wherein:

the set of non-volatile storage elements is in a NAND string.

5. The method of claim 1, further comprising:

providing first binary data, the programming of step (a) is responsive to the first binary data; and

providing second binary data in response to the reading, the further programming of step (c) is responsive to the second binary data but not the first binary data.

6. The method of claim 1, further comprising:

prior to step (a), programming the particular non-volatile storage element using a first page of data, the programming of step (a) is a first programming pass using a second page of data, and the further programming of step (c) is a second programming pass using the second page of data.

7. The method of claim 1, wherein:

the reading includes applying, in turn, a plurality of control gate read voltages which are associated with a corresponding plurality of data states, to the particular non-volatile storage element.

8. A method for operating non-volatile storage, comprising:

performing multi-pass programming operations on a set of non-volatile storage elements which is associated with a set of word lines, the multi-pass programming operations include at least two associated programming passes for each word line, and are performed in an order in which a particular word line, WLn, is subject to one programming pass, after which at least a first additional word line is subject to at least one programming pass, after which WLn is subject to another programming pass;

performing a read operation for WLn after WLn is subject to the one programming pass and before WLn is subject to the another programming pass; and

using results from the read operation to perform the associated additional pass of WLn.

9. The method of claim 8, wherein:

the read operation determines associated target data states of non-volatile storage elements associated with WLn; and

the using the results comprises verifying that the non-volatile storage elements associated with WLn have reached the associated target data states using verify levels which are associated with the associated target data states.

10. The method of claim 8, further comprising:

responsive to the read operation, storing the results as data which identifies associated target data states of non-volatile storage elements associated with WLn; and

accessing the stored data for said using step.

11. The method of claim 8, wherein:

the one programming pass of WLn uses a first set of verify voltages which are offset below respective target data states of the non-volatile storage elements, and the another programming pass of WLn uses a second set of verify voltages which correspond to the associated target data states.

12. The method of claim 8, further comprising:

subjecting at least a second additional word line to at least one programming pass, the read operation is performed after the at least a first additional word line is subject to the at least one programming pass thereof and before the at least a second additional word line is subject to the at least one programming pass thereof.

13. The method of claim 12, wherein:

the set of non-volatile storage elements has a source side and a drain side;

the at least a first additional word line comprises WLn−

1, a source side adjacent word line of WLn; and

the at least a second additional word line comprises WLn+1, a drain side adjacent word line of WLn.

14. The method of claim 8, wherein:

the performing a read operation includes applying, in turn, a plurality of control gate read voltages which are associated with a corresponding plurality of data states, to WLn.

15. The method of claim 8, further comprising:

in response to a program command, storing program data which identifies associated target data states of non-volatile storage elements associated with WLn, the program data is used for the one programming pass of WLn but not for the another programming pass of WLn.

16. The method of claim 8, wherein:

the non-volatile storage elements store multi-bit data.

17. The method of claim 8, further comprising:

performing an error correction process in connection with the read operation; and

performing the another programming pass of WLn using the results of the error correction process.

18. A method for operating non-volatile storage, comprising:

performing multi-pass programming operations on a set of non-volatile storage elements which is associated with a set of word lines, the multi-pass programming operations include at least two associated programming passes for each word line, and are performed in an order in which a particular word line, WLn, is subject to one programming pass, after which at least a first additional word line is subject to at least one programming pass which partially programs non-volatile storage elements associated with WLn;

performing a read operation and an associated error correction process for WLn after WLn is subject to the one programming; and

using results from the read operation and the associated error correction process to perform another programming pass of WLn, thereby completing programming of the non-volatile storage elements associated with WLn.

19. A non-volatile storage apparatus, comprising:

a set of non-volatile storage elements; and

one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits;

(a) program a particular non-volatile storage element of the set to raise its threshold voltage to a first level which is above a first verify level, including verifying that the threshold voltage is above the first verify level, the first verify level is associated with a target data state of the particular non-volatile storage element, (b) read the particular non-volatile storage element after the programming to determine that the threshold voltage has been raised above the first verify level, and (c) responsive to the reading, further program the particular non-volatile storage element to raise its threshold voltage from the first level to a second level which is above a second verify level associated with the target data state.

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

the one or more control circuits determine the target data state from reading the particular non-volatile storage element after the programming.

21. The non-volatile storage apparatus of claim 19, wherein;

the particular non-volatile storage element is series-connected to other non-volatile storage elements in the set of non-volatile storage elements; and

the one or more control circuits program at least one of the other non-volatile storage elements after programming the particular non-volatile storage element and before further programming the particular non-volatile storage element.

22. The non-volatile storage apparatus of claim 19, wherein the one or more control circuits:

provide first binary data;

program the particular non-volatile storage element responsive to the first binary data;

provide second binary data in response to reading the particular non-volatile storage element after the programming; and

further program the particular non-volatile storage element responsive to the second binary data but not the first binary data.

23. The non-volatile storage apparatus of claim 19, wherein:

prior to programming the particular non-volatile storage element to raise its threshold voltage to the first level, the one or more control circuits program the particular non-volatile storage element using a first page of data;

the one or more control circuits program the particular non-volatile storage element to raise its threshold voltage to the first level in a first programming pass using a second page of data; and

the one or more control circuits further program the particular non-volatile storage element in a second programming pass using the second page of data.

24. The non-volatile storage apparatus of claim 19, wherein:

to read the particular non-volatile storage element, the one or more control circuits apply, in turn, a plurality of control gate read voltages which are associated with a corresponding plurality of data states, to the particular non-volatile storage element.