Nonvolatile memory device and related programming method

• US 20070211537A1
• Filed: 03/09/2007
• Published: 09/13/2007
• Est. Priority Date: 03/10/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Min-Gun, Jo, Sung-Jyu
• Granted Patent: US 7,551,487 B2
• Time in Patent Office: Days
• US Class Current: 365/185.220
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/3454 Arrangements for verifying correct programming or for detecting overprogrammed cells
• CPC Class Codes: G11C 16/3459 Circuits or methods to verify correct programming of nonvolatile memory cells

Abstract

In a nonvolatile memory device, a first verification result indicates whether a block of memory cells has been successfully programmed and a second verification result indicates whether a far cell in the block has been is successfully programmed. A controller defines the level and application time for the program voltage applied during a next program loop in response to the first and second verification results.

Claims

1. A nonvolatile memory device, comprising:

a memory cell array comprising memory cells selected by word lines and bit lines;

a row decoder circuit providing a program voltage to a selected word line;

a first verification circuit providing a first verification result indicating whether or not memory cells in a predetermined bit unit and programmed by the program voltage are successfully programmed;

a second verification circuit providing a second verification result indicating whether or not a far cell within the predetermined bit unit is successfully programmed;

a controller defining a level and an application time for a program voltage applied during a next program loop in response to the first and second verification results;

a word line voltage generating circuit generating the program voltage; and

a word line driver supplying the program voltage to the row decoder during the next program loop.

2. The nonvolatile memory device of claim 1, wherein bit lines in the memory cell array are respectively connected to a plurality of physical input/output (I/O) lines including an I/O line connected to the far cell and communicating a data value for the far cell to the second verification circuit.

3. The nonvolatile memory device of claim 1, wherein the first verification circuit verifies successful programming of the memory cells in the predetermined bit unit in parallel.

4. The nonvolatile memory device of claim 1, wherein the first and second verification results are respectively generated in parallel by the first and second verification circuits.

5. The nonvolatile memory device of claim 1, wherein the controller comprises:

a control logic generating a count-up signal indicating the program loop and a program state enable signal activating the next program loop in response to the first verification result;

a program voltage adjustor generating a program step code corresponding to the level of the program voltage in response to the count-up signal; and

a program time adjustor determining an end point for the program loop in response to the program state enable signal and the second verification result,

wherein the control logic deactivates the program state enable signal in accordance with the determined end point.

6. The nonvolatile memory device of claim 5, wherein the control logic implements a state machine responsive to state information indicating whether or not a current programming operation is successfully completed.

7. The nonvolatile memory device of claim 5, wherein the program time adjustor comprises:

a counter counting an elapsed time following activation of the program state enable signal and generating a corresponding counted value; and

a decoder decoding a program state end signal in response to the counted value and the second verification result.

8. The nonvolatile memory device of claim 7, wherein the decoder delays the program state end signal by a predetermined time when the second verification results indicates a unsuccessful programming of the far cell.

9. The nonvolatile memory device of claim 7, wherein the decoder advances the program state end signal by a predetermined time when the second verification circuit indicates successful programming of the far cell.

10. The nonvolatile memory device of claim 5, wherein the word line driver supplies the program voltage to the row decoder circuit during a period of when the program state enable signal is activated.

11. The nonvolatile memory device of claim 1, wherein the first and second verification circuits are implemented using a wired-OR type circuit or a column scan type circuit.

12. A method for programming a non-voltage memory device having memory cells selected by word lines and bit lines, the method comprising:

applying a program voltage to a selected word line through a row decoder;

verifying whether or not memory cells in a predetermined bit unit programmed by the program voltage are successfully programmed and providing a corresponding first verification result;

verifying whether or not a far cell amongst the memory cells in the predetermined bit unit is successfully programmed and providing a corresponding second verification result; and

adjusting a level and application time for a program voltage applied during a next program loop in response to the first and second verification results.

13. The method of claim 12, wherein the adjusting of the level and application time for the program voltage comprises:

generating a count-up signal indicating the program loop and a program state enable signal activating the next program loop in response to the first verification result;

generating a program step code corresponding to the level of the program voltage in response to the count-up signal;

determining an end point of the program loop in response to the program state enable signal and the second verification result; and

deactivating the program state enable signal according to the determined end point.

14. The method of claim 12, wherein the determining of the program state end point comprises:

counting an elapsed time following activation of the program state enable signal and generating a corresponding counted value; and

generating a program state end signal in response to the counted value and the second verification result.

15. The method of claim 14, wherein the program state end signal is delayed by a predetermined time when the second verification result indicates that the far cell is not successfully programmed.

16. The method of claim 14, wherein the program state end signal is advanced by a predetermined time when the second verification result indicates that the far cell is successfully programmed.