Selective application of program inhibit schemes in non-volatile memory

• US 7,295,478 B2
• Filed: 05/12/2005
• Issued: 11/13/2007
• Est. Priority Date: 05/12/2005
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Wan, Jun, Gongwer, Geoffrey S., Chen, Jian, Hemink, Gerrit Jan, Oowada, Ken, Lutze, Jeffrey, Higashitani, Masaaki
• Primary Examiner(s): Elms; Richard T.
• Assistant Examiner(s): Nguyen; N
• Application Number:
  US11/127,743
• Publication Number:
  US 20060279990A1
• Time in Patent Office: 915 Days
• Field of Search: 365/195, 365/189.07, 365/189.09, 365/211
• US Class Current: 365/195
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data

Abstract

A non-volatile memory system is programmed so as to reduce or avoid program disturb. In accordance with one embodiment, multiple program inhibit schemes are employed for a single non-volatile memory system. Program inhibit schemes are selected based on the word line being programmed. Certain program inhibit schemes have been discovered to better minimize or eliminate program disturb at select word lines. In one embodiment, selecting a program inhibit scheme includes selecting a program voltage pulse ramp rate. Different ramp rates have been discovered to better minimize program disturb when applied to select word lines. In another embodiment, the temperature of a memory system is detected before or during a program operation. A program inhibit scheme can be selected based on the temperature of the system.

Claims

1. A method of programming non-volatile storage, comprising:

determining which of a plurality of word lines is to receive a program voltage signal for programming, said word line is coupled to a first non-volatile storage element of a first group of non-volatile storage elements and a second non-volatile storage element of a second group of non-volatile storage elements, said first non-volatile storage element is to be inhibited from programming and said second non-volatile storage element is to be programmed;

selecting a program inhibit scheme based on said word line that is to receive said program voltage signal;

boosting a voltage potential of a channel of said first group of non-volatile storage elements using said selected program inhibit scheme; and

enabling programming of said second group of non-volatile storage elements.

2. The method of claim 1, wherein said step of selecting a program inhibit scheme includes:

selecting said program inhibit scheme based on an order of programming of said plurality of word lines.

3. The method of claim 2, wherein selecting said program inhibit scheme based on an order of programming includes:

determining whether said word line that is to receive said program voltage signal is in a first range or a second range of said plurality of word lines, said first range is programmed prior to said second range; and

selecting a first program inhibit scheme if said word line is in said first range and selecting a second program inhibit scheme if said word line is in said second range.

4. The method of claim 3, wherein:

said first program inhibit scheme is a self-boosting program inhibit scheme; and

said second program inhibit scheme is an erased area self-boosting scheme.

5. The method of claim 4, wherein:

said word line is in said first range; and

said step of boosting said voltage potential of said channel using said self-boosting program inhibit scheme includes;

applying said program voltage signal to said word line that is to receive said program voltage signal, and

applying a pass voltage to each unselected word line of said plurality of word lines.

6. The method of claim 3, wherein:

said word line is in said second range;

said plurality of word lines includes a neighboring word line adjacent to said word line in a source side direction; and

said step of boosting said voltage potential of said channel of said first group using said second program inhibit scheme includes;

applying said program voltage to said word line that is to receive said program voltage signal,

applying zero volts to said source side adjacent word line, and

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

7. The method of claim 3, wherein:

said word line is in said second range;

said plurality of word lines includes a word line adjacent to said word line in a source side direction and a word line adjacent to said world line in a drain side direction; and

said step of boosting said voltage potential of said channel of said first group using said second program inhibit scheme includes;

applying said program voltage to said word line that is to receive said program voltage signal,

applying zero volts to said source side adjacent word line,

applying zero volts to said drain side adjacent word line, and

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

8. The method of claim 3, wherein:

said word line is in said second range;

said plurality of word lines includes a second word line adjacent to said word line in a source side direction;

said plurality of word lines includes a third word line adjacent to said second word line in said source side direction; and

said step of boosting said voltage potential of said channel of said first group using said second program inhibit scheme includes;

applying said program voltage to said word line that is to receive said program voltage signal,

applying a first voltage to said second word line, said first voltage is greater than zero volts,

applying zero volts to said third word line, and

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

9. The method of claim 1, wherein:

said step of selecting a program inhibit scheme based on said word line that is to receive said program voltage signal includes selecting a ramp rate for pulses of said program voltage signal.

10. The method of claim 9, wherein said step of selecting a program inhibit scheme comprises:

selecting a first ramp rate for said pulses of said program voltage signal if said word line is in a first range or a second ramp rate if said word line is in a second range of said plurality of word lines.

11. The method of claim 10, wherein:

said first range is programmed prior to said second range; and

said first ramp rate is slower than said second ramp rate.

12. The method of claim 1, wherein:

said first group and said second group are part of an array of non-volatile storage elements;

said array is in communication with a host system; and

said array is removable from said host system.

13. The method of claim 1, wherein:

said first group and said second group are part of an array of non-volatile storage elements;

said array is in communication with a host system; and

said array is embedded in said host system.

14. The method of claim 1, wherein:

said first group of non-volatile storage elements and said second group of non-volatile storage elements are groups of multi-state non-volatile storage elements.

15. The method of claim 1, wherein:

said first group of non-volatile storage elements and said second group of non-volatile storage elements are groups of binary non-volatile storage elements.

16. The method of claim 1, wherein:

said first group of non-volatile storage elements is a first NAND string; and

said second group of non-volatile storage elements is a second NAND string.

17. A method of programming non-volatile storage, comprising:

determining a temperature of said non-volatile storage, said non-volatile storage including a first group of non-volatile storage elements to be inhibited from programming and a second group of non-volatile storage elements to be enabled for programming;

selecting a program inhibit scheme based on said temperature;

boosting a voltage potential of a channel of said first group of non-volatile storage elements using said selected program inhibit scheme; and

enabling programming of said second group of non-volatile storage elements.

18. The method of claim 17, wherein said step of selecting a program inhibit scheme includes:

determining whether said temperature is above a breakpoint level;

selecting a first program inhibit scheme if said temperature is above said breakpoint level; and

selecting a second program inhibit scheme if said temperature is below said breakpoint level.

19. The method of claim 18, wherein:

said first program inhibit scheme is a self-boosting program inhibit scheme; and

said second program inhibit scheme is a revised erased area self-boosting scheme.

20. The method of claim 18, wherein:

said first group of non-volatile storage elements includes a first non-volatile storage element to be inhibited from programming, said first non-volatile storage element is coupled to a first word line of said plurality of word lines;

said second group of non-volatile storage elements includes a second non-volatile storage element to be programmed, said second non-volatile storage element is coupled to said first word line;

said step of boosting said voltage potential of said channel region using said first program inhibit scheme comprises;

applying said program voltage signal to said first word line, and

applying a pass voltage to each unselected word line of said plurality of word lines.

21. The method of claim 18, wherein:

said first group of non-volatile storage elements includes a first non-volatile storage element to be inhibited from programming, said first non-volatile storage element is coupled to a first word line of said plurality of word lines, said plurality of word lines includes a second word line adjacent to said first word line in a source side direction; and

said second group of non-volatile storage elements includes a second non-volatile storage element to be programmed, said second non-volatile storage element is coupled to said first word line;

said step of boosting said voltage potential of said channel region using said second program inhibit scheme comprises;

applying said program voltage to said first word line,

applying zero volts to said second word line, and

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

22. The method of claim 18, wherein:

said first group of non-volatile storage elements includes a first non-volatile storage element to be inhibited from programming, said first non-volatile storage element is coupled to a first word line of said plurality of word lines, said plurality of word lines includes a second word line adjacent to said first word line in a source side direction and a third word line adjacent to said first word line in a drain side direction;

said second group of non-volatile storage elements includes a second non-volatile storage element to be programmed, said second non-volatile storage element is coupled to said first word line; and

said step of boosting said voltage potential of said channel region using said second program inhibit scheme comprises;

applying said program voltage to said first word line,

applying zero volts to said second word line,

applying zero volts to said third word line, and

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

23. The method of claim 18, wherein:

said first group of non-volatile storage elements includes a first non-volatile storage element to be inhibited from programming, said first non-volatile storage element is coupled to a first word line of said plurality of word lines, said plurality of word lines includes a second word line adjacent to said first word line in a source side direction and a third word line adjacent to said second word line in a source side direction;

said second group of non-volatile storage elements includes a second non-volatile storage element to be programmed, said second non-volatile storage element is coupled to said first word line;

said step of boosting said voltage potential of said channel region using said second program inhibit scheme comprises;

applying said program voltage to said first word line,

applying a first voltage to said second word line, said first voltage is greater than zero volts,

applying zero volts to said third word line,

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

24. The method of claim 17, wherein:

said first group and said second group are part of an array of non-volatile storage elements;

said array is in communication with a host system; and

said array is removable from said host system.

25. The method of claim 17, wherein:

said first group of non-volatile storage elements and said second group of non-volatile storage elements are groups of multi-state non-volatile storage elements.

26. The method of claim 17, wherein:

said first group of non-volatile storage elements is a first NAND string; and

said second group of non-volatile storage elements is a second NAND string.

27. A non-volatile memory system, comprising:

a plurality of word lines;

a first group of non-volatile storage elements having a first non-volatile storage element to be inhibited from programming;

a second group of non-volatile storage elements having a second non-volatile storage element to be programmed; and

managing circuitry in communication with said plurality of word lines and said first and second groups of non-volatile storage elements, said managing circuitry programs said second non-volatile storage element by;

determining which word line of said plurality of word lines is coupled to said second non-volatile storage element, said word line is a first word line and is also coupled to said first non-volatile storage element,

selecting a program inhibit scheme based on said first word line being selected for programming,

boosting a voltage potential of a channel of said first group of non-volatile storage elements using said selected program inhibit scheme, and

enabling programming of said second group of non-volatile storage elements.

28. The non-volatile memory system of claim 27, wherein said step of selecting a program inhibit scheme includes:

selecting said program inhibit scheme based on an order of programming of said plurality of word lines.

29. The non-volatile memory system of claim 28 wherein selecting said program inhibit scheme based on an order of programming includes:

determining whether said first word line is in a first range or a second range of said plurality of word lines, said first range is programmed prior to said second range; and

selecting a first program inhibit scheme if said word line is in said first range and selecting a second program inhibit scheme if said word line is in said second range.

30. The non-volatile memory system of claim 29, wherein:

said first program inhibit scheme is a self-boosting program inhibit scheme; and

said second program inhibit scheme is a revised erased area self-boosting scheme.

31. The non-volatile memory system of claim 29, wherein:

said first word line is in said first range;

said step of boosting said voltage potential of said channel using said first program inhibit scheme includes;

applying said program voltage signal to said first word line, and

applying a pass voltage to each unselected word line of said plurality of word lines.

32. The non-volatile memory system of claim 29, wherein:

said first word line is in said second range;

said plurality of word lines includes a second word line adjacent to said first word line in a source side direction;

said plurality of word lines includes a third word line adjacent to said second word line in said source side direction;

said step of boosting said voltage potential of said channel of said first group using said second program inhibit scheme includes;

applying said program voltage to said first word line,

applying a first voltage to said second word line, said first voltage is greater than zero volts,

applying zero volts to said third word line,

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

33. The non-volatile memory system of claim 27, wherein:

said step of selecting a program inhibit scheme based on said first word line being selected for programming includes selecting a ramp rate for pulses of said program voltage signal.

34. The non-volatile memory system of claim 33, wherein said step of selecting a program inhibit scheme comprises:

selecting a first ramp rate for said pulses of said program voltage signal if said word line is in a first range of said plurality of word lines; and

selecting a second ramp rate for said pulses of said program voltage signal if said word line is in a second range of said plurality of word lines.

35. The non-volatile memory system of claim 34, wherein:

said first range is programmed prior to said second range; and

said first ramp rate is slower than said second ramp rate.

36. The non-volatile memory system of claim 27, wherein:

said first group and said second group are part of an array of non-volatile storage elements;

said array is in communication with a host system; and

said array is removable from said host system.

37. The non-volatile memory system of claim 27, wherein:

said first group of non-volatile storage elements and said second group of non-volatile storage elements are groups of multi-state non-volatile storage elements.

38. The non-volatile memory system of claim 27, wherein:

said first group of non-volatile storage elements is a first NAND string; and

said second group of non-volatile storage elements is a second NAND string.

39. The non-volatile memory system of claim 27, wherein:

said managing circuitry includes at least one of a state machine, a controller, and a processor.

40. A non-volatile memory system, comprising:

a plurality of word lines;

a first group of non-volatile storage elements having a first non-volatile storage element to be inhibited from programming, said first non-volatile storage element is coupled to a first word line;

a second group of non-volatile storage elements having a second non-volatile storage element to be programmed, said second non-volatile storage element is coupled to said first word line;

a temperature sensor; and

managing circuitry in communication with said plurality of word lines, said first and second groups of non-volatile storage elements, and said temperature sensor, said managing circuit programs said second non-volatile storage element by;

determining a temperature of said non-volatile memory system from said temperature sensor,

selecting a program inhibit scheme based on said temperature,

boosting a voltage potential of a channel of said first group of non-volatile storage elements using said selected program inhibit scheme, and

enabling programming of said second group of non-volatile storage elements.

41. The non-volatile memory system of claim 40, wherein said step of selecting a program inhibit scheme includes:

determining whether said temperature is above a breakpoint level;

selecting a first program inhibit scheme if said temperature is above said breakpoint level; and

selecting a second program inhibit scheme if said temperature is below said breakpoint level.

42. The non-volatile memory system of claim 41, wherein:

said first program inhibit scheme is a self-boosting program inhibit scheme; and

said second program inhibit scheme is a revised erased area self-boosting scheme.

43. The non-volatile memory system of claim 41, wherein said step of boosting said voltage potential of said channel region using said first program inhibit scheme comprises:

applying said program voltage signal to said first word line, and

applying a pass voltage to each unselected word line of said plurality of word lines.

44. The non-volatile memory system of claim 41, wherein:

said plurality of word lines includes a second word line adjacent to said first word line in a source side direction and a third word line adjacent to said second word line in a source side direction;

said step of boosting said voltage potential of said channel region using said second program inhibit scheme comprises;

applying said program voltage to said first word line,

applying a first voltage to said second word line, said first voltage is greater than zero volts,

applying zero volts to said third word line,

applying a pass voltage to each remaining unselected word line of said plurality of word lines.

45. The non-volatile memory system of claim 40, wherein:

said first group and said second group are part of an array of non-volatile storage elements;

said array is in communication with a host system; and

said array is removable from said host system.

46. The non-volatile memory system of claim 40, wherein:

said first group of non-volatile storage elements and said second group of non-volatile storage elements are groups of multi-state non-volatile storage elements.

47. The non-volatile memory system of claim 40, wherein:

said first group of non-volatile storage elements is a first NAND string; and

said second group of non-volatile storage elements is a second NAND string.

48. The non-volatile memory system of claim 40, wherein:

said managing circuitry includes at least one of a processor, a controller, and a state machine.

49. A method of programming non-volatile storage, comprising:

programming one or more non-volatile storage elements coupled to a first word line, said programming includes;

boosting a voltage potential of a channel of a first group of non-volatile storage elements having a first non-volatile storage element to be inhibited from programming, said first non-volatile storage element is coupled to said first word line, said boosting is accomplished according to a first program inhibit scheme, and

enabling programming of a second group of non-volatile storage elements having a second non-volatile storage element to be programmed, said second non-volatile storage element is coupled to said first word line; and

programming one or more non-volatile storage elements coupled to a second word line, said programming includes;

boosting a voltage potential of said channel of said first group of non-volatile storage elements having a third non-volatile storage element to be inhibited from programming, said third non-volatile storage element is coupled to said second word line, said boosting is accomplished according to a second program inhibit scheme, and

enabling programming of said second group of non-volatile storage elements having a fourth non-volatile storage element to be programmed, said fourth non-volatile storage element is coupled to said second word line.

50. The method of claim 49, wherein:

said first word line is programmed prior to programming said second word line for said non-volatile memory system.

51. The method of claim 50, wherein:

said first program inhibit scheme is a self-boosting scheme;

said second program inhibit scheme is a revised erased area self-boosting scheme.