MEMORY SYSTEM HAVING NAND-BASED NOR AND NAND FLASHES AND SRAM INTEGRATED IN ONE CHIP FOR HYBRID DATA, CODE AND CACHE STORAGE

• US 20100329011A1
• Filed: 02/05/2010
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Aplus Flash Technology, Inc.
• Original Assignee: Aplus Flash Technology, Inc.
• Inventors: Lee, Peter Wung, Wang, Kesheng, Hsu, Fu-Chang
• Granted Patent: US 8,149,622 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 7/1075 for multiport memories each having random access ports and serial ports, e.g. video RAM
• CPC Class Codes: G11C 8/16 Multiple access memory array, e.g. addressing one storage element via at least two independent addressing line groups

Abstract

A memory system includes a NAND flash memory, a NOR flash memory and a SRAM manufactured on a single chip. Both NAND and NOR memories are manufactured by the same NAND manufacturing process and NAND cells. The three memories share the same address bus, data bus, and pins of the single chip. The address bus is bi-directional for receiving codes, data and addresses and transmitting output. The data bus is also bi-directional for receiving and transmitting data. One external chip enable pin and one external output enable pin are shared by the three memories to reduce the number of pins required for the single chip. Both NAND and NOR memories have dual read page buffers and dual write page buffers for Read-While-Load and Write-While-Program operations to accelerate the read and write operations respectively. A memory-mapped method is used to select different memories, status registers and dual read or write page buffers.

Claims

1. A memory system on a single chip, comprising:

a NAND flash memory having a status register and a plurality of NAND cells, said plurality of NAND cells having a plurality of bit lines, a plurality of source lines in parallel with said bit lines, and a plurality of word lines perpendicular to said bit lines and said source lines;

a NOR flash memory having a status register and a plurality of NOR cells, each of said NOR cells being formed by a symmetrical 2-NAND cell string and having a drain connected to a bit line, a source connected to a source line in parallel with said bit line and two floating gates connected to two word lines perpendicular to said bit line and said source line;

an address bus shared by said NAND and NOR flash memories, and

a data bus shared by said NAND and NOR flash memories;

wherein both said address bus and said data bus are bi-directional for receiving external inputs to said memory system and transmitting outputs from said memory system, and said NAND and NOR flash memories are manufactured by a unified NAND manufacturing process and same NAND cells.

2. The memory system on a single die as claimed in claim 1, wherein said NAND and NOR flash memories use a same FN-tunneling scheme to perform page program, page erase and block erase operations.

3. The memory system on a single die as claimed in claim 1, wherein said memory system has NAND-based software commands for providing compatible NOR-based command set and NAND-based command set.

4. The memory system on a single die as claimed in claim 1, wherein said address bus is used for receiving code, data and address of said NAND and NOR flash memories, and outputting content of said status registers of said NAND and NOR flash memories.

5. The memory system on a single die as claimed in claim 1, wherein said memory system has an asynchronous status register read command for reading out content of said status register of said NAND flash memory or said NOR flash memory from said address bus.

6. The memory system on a single die as claimed in claim 1, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories.

7. The memory system on a single die as claimed in claim 6, wherein said NAND and NOR flash memories are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

8. The memory system on a single die as claimed in claim 6, wherein said status register of said NAND flash memory and said status register of said NOR flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

9. The memory system on a single die as claimed in claim 1, wherein said single chip has a plurality of pins shared by said NAND and NOR flash memories, and definition of said plurality of pins are based on pin definition of said NOR flash memory with additional pin definition added to meet requirements for said NAND flash memory.

10. The memory system on a single die as claimed in claim 1, wherein said single chip has separate internal RY/BY# signals for said NAND and NOR flash memories inside said single chip with an external RY/BY# pin shared by said NAND and NOR flash memories.

11. The memory system on a single die as claimed in claim 10, wherein a host issues an instruction to determine if said NAND flash memory or said NOR flash memory has a completed write operation that activates said external RY/BY# pin, and then resets said external RY/BY# pin to wait for completion of an additional write operation of said NAND flash memory or said NOR flash memory.

12. The memory system on a single die as claimed in claim 1, wherein said memory system has a synchronous read command for reading said NAND and NOR flash memories simultaneously by outputting data of said NAND and NOR flash memories alternatively on said data bus.

13. The memory system on a single die as claimed in claim 1, wherein said NAND flash memory further comprises dual read page buffers.

14. The memory system on a single die as claimed in claim 13, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories.

15. The memory system on a single die as claimed in claim 14, wherein said dual read page buffers of said NAND flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

16. The memory system on a single die as claimed in claim 13, wherein said NAND flash memory further comprises a Read-While-Load operation for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said NAND flash memory to the other read page buffer.

17. The memory system on a single die as claimed in claim 13, wherein said NAND flash memory further comprises a Read-While-Load section operation with one of said dual read page buffers for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said NAND flash memory to another section of said one read page buffer.

18. The memory system on a single die as claimed in claim 1, wherein said NAND flash memory further comprises dual write page buffers.

19. The memory system on a single die as claimed in claim 18, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories.

20. The memory system on a single die as claimed in claim 19, wherein said dual write page buffers of said NAND flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

21. The memory system on a single die as claimed in claim 18, wherein said NAND flash memory further comprises a Write-While-Program operation for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to said NAND flash memory from the other write page buffer.

22. The memory system on a single die as claimed in claim 18, wherein said NAND flash memory further comprises dual read page buffers, said NAND flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part operation on one part of said NAND flash memory for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said one part of said NAND flash memory to the other read page buffer;

while a simultaneous Program/Write/Write-While-Program operation on the other part of said NAND flash memory for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to the other part of said NAND flash memory from the other write page buffer.

23. The memory system on a single die as claimed in claim 18, wherein said NAND flash memory further comprises a Write-While-Program section operation with one of said dual write page buffers for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to said NAND flash memory from another section of said one write page buffer.

24. The memory system on a single die as claimed in claim 18, wherein said NAND flash memory further comprises dual read page buffers, said NAND flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part section operation with one of said dual read page buffers on one part of said NAND flash memory for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said one part of said NAND flash memory to another section of said one read page buffer;

while a simultaneous Program/Write/Write-While-Program section operation with one of said dual write page buffers on the other part of said NAND flash memory for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to the other part of said NAND flash memory from another section of said one write page buffer.

25. The memory system on a single die as claimed in claim 1, wherein said NOR flash memory further comprises dual read page buffers.

26. The memory system on a single die as claimed in claim 25, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories.

27. The memory system on a single die as claimed in claim 26, wherein said dual read page buffers of said NOR flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

28. The memory system on a single die as claimed in claim 25, wherein said NOR flash memory further comprises a Read-While-Load operation for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said NOR flash memory to the other read page buffer.

29. The memory system on a single die as claimed in claim 25, wherein said NOR flash memory further comprises a Read-While-Load section operation with one of said dual read page buffers for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said NOR flash memory to another section of said one read page buffer.

30. The memory system on a single die as claimed in claim 1, wherein said NOR flash memory further comprises dual write page buffers.

31. The memory system on a single die as claimed in claim 30, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories.

32. The memory system on a single die as claimed in claim 31, wherein said dual write page buffers of said NOR flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

33. The memory system on a single die as claimed in claim 30, wherein said NOR flash memory further comprises a Write-While-Program operation for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to said NOR flash memory from the other write page buffer.

34. The memory system on a single die as claimed in claim 30, wherein said NOR flash memory further comprises dual read page buffers, said NOR flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part operation on one part of said NOR flash memory for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said one part of said NOR flash memory to the other read page buffer;

while a simultaneous Program/Write/Write-While-Program operation on the other part of said NOR flash memory for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to the other part of said NOR flash memory from the other write page buffer.

35. The memory system on a single die as claimed in claim 30, wherein said NOR flash memory further comprises a Write-While-Program section operation with one of said dual write page buffers for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to said NOR flash memory from another section of said one write page buffer.

36. The memory system on a single die as claimed in claim 30, wherein said NOR flash memory further comprises dual read page buffers, said NOR flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part section operation with one of said dual read page buffers on one part of said NOR flash memory for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said one part of said NOR flash memory to another section of said one read page buffer;

while a simultaneous Program/Write/Write-While-Program section operation with one of said dual write page buffers on the other part of said NOR flash memory for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to the other part of said NOR flash memory from another section of said one write page buffer.

37. The memory system on a single die as claimed in claim 1, further comprising a SRAM having a plurality of SRAM cells integrated in said single die.

38. The memory system on a single die as claimed in claim 37, wherein said NAND and NOR flash memories use a same FN-tunneling scheme to perform page program, page erase and block erase operations.

39. The memory system on a single die as claimed in claim 37, wherein said memory system has NAND-based software commands for providing compatible NOR-based command set and NAND-based command set.

40. The memory system on a single die as claimed in claim 37, wherein said address bus and said data bus are shared by said NOR and NAND flash memories, and said SRAM.

41. The memory system on a single die as claimed in claim 37, wherein said address bus is used for receiving code, data and address of said NAND and NOR flash memories, and address of said SRAM, and outputting content of said status registers of said NAND and NOR flash memories.

42. The memory system on a single die as claimed in claim 37, wherein said memory system has an asynchronous status register read command for reading out content of said status register of said NAND flash memory or said NOR flash memory from said address bus.

43. The memory system on a single die as claimed in claim 37, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories, and said SRAM.

44. The memory system on a single die as claimed in claim 43, wherein said NAND and NOR flash memories, and said SRAM are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

45. The memory system on a single die as claimed in claim 43, wherein said status register of said NAND flash memory and said status register of said NOR flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

46. The memory system on a single die as claimed in claim 37, wherein said single chip has a plurality of pins shared by said NAND and NOR flash memories, and said SRAM, and definition of said plurality of pins are based on pin definition of said NOR flash memory with additional pin definition added to meet requirements for said NAND flash memory and said SRAM.

47. The memory system on a single die as claimed in claim 37, wherein said single chip has separate internal RY/BY# signals for said NAND and NOR flash memories inside said single chip with an external RY/BY# pin shared by said NAND and NOR flash memories.

48. The memory system on a single die as claimed in claim 47, wherein a host issues an instruction to determine if said NAND flash memory or said NOR flash memory has a completed write operation that activates said external RY/BY# pin, and then resets said external RY/BY# pin to wait for competition of an additional operation of said NAND flash memory or said NOR flash memory.

49. The memory system on a single die as claimed in claim 37, wherein said memory system has a synchronous read command for reading said NAND and NOR flash memories simultaneously by outputting data of said NAND and NOR flash memories alternatively on said data bus.

50. The memory system on a single die as claimed in claim 37, wherein said NAND flash memory further comprises dual read page buffers.

51. The memory system on a single die as claimed in claim 50, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories, and said SRAM.

52. The memory system on a single die as claimed in claim 51, wherein said dual read page buffers of said NAND flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

53. The memory system on a single die as claimed in claim 50, wherein said NAND flash memory further comprises a Read-While-Load operation for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said NAND flash memory to the other read page buffer.

54. The memory system on a single die as claimed in claim 50, wherein said NAND flash memory further comprises a Read-While-Load section operation with one of said dual read page buffers for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said NAND flash memory to another section of said one read page buffer.

55. The memory system on a single die as claimed in claim 37, wherein said NAND flash memory further comprises dual write page buffers.

56. The memory system on a single die as claimed in claim 55, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories, and said SRAM.

57. The memory system on a single die as claimed in claim 56, wherein said dual write page buffers of said NAND flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

58. The memory system on a single die as claimed in claim 55, wherein said NAND flash memory further comprises a Write-While-Program operation for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to said NAND flash memory from the other write page buffer.

59. The memory system on a single die as claimed in claim 55, wherein said NAND flash memory further comprises dual read page buffers, said NAND flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part operation on one part of said NAND flash memory for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said one part of said NAND flash memory to the other read page buffer;

while a simultaneous Program/Write/Write-While-Program operation on the other part of said NAND flash memory for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to the other part of said NAND flash memory from the other write page buffer.

60. The memory system on a single die as claimed in claim 55, wherein said NAND flash memory further comprises a Write-While-Program section operation with one of said dual write page buffers for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to said NAND flash memory from another section of said one write page buffer.

61. The memory system on a single die as claimed in claim 55, wherein said NAND flash memory further comprises dual read page buffers, said NAND flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part section operation with one of said dual read page buffers on one part of said NAND flash memory for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said one part of said NAND flash memory to another section of said one read page buffer;

while a simultaneous Program/Write/Write-While-Program section operation with one of said dual write page buffers on the other part of said NAND flash memory for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to the other part of said NAND flash memory from another section of said one write page buffer.

62. The memory system on a single die as claimed in claim 37, wherein said NOR flash memory further comprises dual read page buffers.

63. The memory system on a single die as claimed in claim 62, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories, and said SRAM.

64. The memory system on a single die as claimed in claim 63, wherein said dual read page buffers of said NOR flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

65. The memory system on a single die as claimed in claim 62, wherein said NOR flash memory further comprises a Read-While-Load operation for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said NOR flash memory to the other read page buffer.

66. The memory system on a single die as claimed in claim 62, wherein said NOR flash memory further comprises a Read-While-Load section operation with one of said dual read page buffers for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said NOR flash memory to another section of said one read page buffer.

67. The memory system on a single die as claimed in claim 37, wherein said NOR flash memory further comprises dual write page buffers.

68. The memory system on a single die as claimed in claim 67, wherein said single chip has one single external output enable (OE) pin and one single external chip enable (CE) pin shared by said NAND and NOR flash memories, and said SRAM.

69. The memory system on a single die as claimed in claim 68, wherein said dual write page buffers of said NOR flash memory are selected by a memory-mapped method using different addresses together with said single external OE pin and said single external CE pin.

70. The memory system on a single die as claimed in claim 67, wherein said NOR flash memory further comprises a Write-While-Program operation for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to said NOR flash memory from the other write page buffer.

71. The memory system on a single die as claimed in claim 67, wherein said NOR flash memory further comprises dual read page buffers, said NOR flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part operation on one part of said NOR flash memory for executing a data-read operation from one of said dual read page buffers during a simultaneous data-load operation from said one part of said NOR flash memory to the other read page buffer;

while a simultaneous Program/Write/Write-While-Program operation on the other part of said NOR flash memory for executing a data-write operation to one of said dual write page buffers during a simultaneous data-program operation to the other part of said NOR flash memory from the other write page buffer.

72. The memory system on a single die as claimed in claim 67, wherein said NOR flash memory further comprises a Write-While-Program section operation with one of said dual write page buffers for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to said NOR flash memory from another section of said one write page buffer.

73. The memory system on a single die as claimed in claim 67, wherein said NOR flash memory further comprises dual read page buffers, said NOR flash memory is divided into two parts, and said memory system has a Load/Read/Read-While-Load dual-part section operation with one of said dual read page buffers on one part of said NOR flash memory for executing a data-read operation from one section of said one read page buffer during a simultaneous data-load operation from said one part of said NOR flash memory to another section of said one read page buffer;

while a simultaneous Program/Write/Write-While-Program section operation with one of said dual write page buffers on the other part of said NOR flash memory for executing a data-write operation to one section of said one write page buffer during a simultaneous data-program operation to the other part of said NOR flash memory from another section of said one write page buffer.