Flash memory device error correction code controllers and related methods and memory systems

• US 8,112,692 B2
• Filed: 01/25/2011
• Issued: 02/07/2012
• Est. Priority Date: 01/08/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Chang-Duck, Heo, Seok-won, Park, Si-Yung, Lee, Dong-Ryoul
• Primary Examiner(s): ABRAHAM, ESAW T
• Application Number:
  US13/012,984
• Publication Number:
  US 20110119561A1
• Time in Patent Office: 378 Days
• Field of Search: 714/763, 714/782, 365/185.09, 365/185.33
• US Class Current: 714/763
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G06F 12/0238 Memory management in non-volatile memory, e.g. resistive RAM or ferroelectric memory
• CPC Class Codes: G06F 13/1668 Details of memory controller
• CPC Class Codes: H03M 13/15 Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes H03M13/17 takes precedence
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/152 Bose-Chaudhuri-Hocquenghem [BCH] codes
• CPC Class Codes: H03M 13/19 Single error correction without using particular properties of the cyclic codes, e.g. Hamming codes, extended or generalised Hamming codes
• CPC Class Codes: H03M 13/23 using convolutional codes, e.g. unit memory codes
• CPC Class Codes: H03M 13/35 Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
• CPC Class Codes: H03M 13/3715 Adaptation to the number of estimated errors or to the channel state

Abstract

An ECC controller for a flash memory device storing M-bit data (M: a positive integer equal to or greater than 2) includes an encoder and a decoder. The encoder generates first ECC data for input data to be stored in the flash memory device using a first error correction scheme and generates second ECC data for the input data using a second error correction scheme. The input data, the first ECC data, and the second ECC data are stored in the flash memory device. The decoder calculates the number of errors in data read from the flash memory device and corrects the errors in the read data using one of the first ECC data and the second ECC data selectively based on the number of the errors.

Claims

1. A method for correcting errors in data that is stored in a memory device, the method comprising:

reading the data along with first error correction code (ECC) data and second ECC data from the memory device;

determining a number of errors in the read data; and

selecting one of the first ECC data or the second ECC data for use in correcting the errors in the read data based on the determined number of the errors.

2. The method of claim 1, wherein the first ECC data is generated using a first error correction scheme and wherein the second ECC data is generated using a second error correction scheme.

3. The method of claim 2, wherein the first error correction scheme is a high-speed error correction scheme that supports an on-the-fly function and the second error correction scheme is a high-performance error correction scheme that does not support the on-the-fly function.

4. The method of claim 2, wherein at least one of the error correction schemes is an error correction scheme that uses a Bose-Chaudhuri-Hocquenghem (BCH) code.

5. The method of claim 2, wherein the first error correction scheme is an error correction scheme that uses a Bose-Chaudhuri-Hocquenghem (BCH) code, and wherein the second error correction scheme is an error correction scheme that is different from the BCH code.

6. The method of claim 1, wherein the first ECC data is selected for use in correcting the errors in the read data if the number of errors in the read data is a predetermined value or less.

7. The method of claim 1, wherein the memory device is configured to store M-bit data, M being a positive integer equal to or greater than 2.

8. The method of claim 7, wherein a memory cell array of the memory device includes a data area and a spare area, and wherein the input data is stored in the data area, and wherein the first ECC data and the second ECC data are stored in the spare area.

9. The method of claim 7, wherein a memory cell array of the memory device includes a data area and a second area, and wherein the input data is stored in the data area, and wherein at least one of the first ECC data and the second ECC data is stored in the second area.

10. The method of claim 1, wherein a memory cell array of the memory device includes a data area and a second area, and wherein each of the memory cells in the data area stores M-bit data, and each of the memory cells in the second area stores 1-bit data.

11. The method of claim 1, wherein the memory device is one of a NAND flash memory device, a NOR flash memory device, a phase change random access memory (PRAM) device or a magnetic random access memory (MRAM) device.

12. A memory device, comprising:

a memory cell array; and

an error correction code (ECC) circuit that is configured to generate first error correction code data using a first error correction scheme and second ECC data using a second error correction scheme, the first and second ECC data each corresponding to data read from the memory cell array, wherein the ECC circuit is further configured to select one of the first ECC data or the second ECC data for use in correcting the errors in the data read from the memory cell array based on a determined number of errors in the data read from the memory cell array.

13. The memory device of claim 12, wherein the first ECC data is selected for use in correcting the errors in the read data if the number of errors in the read data is a predetermined value or less.

14. The memory device of claim 12, wherein the memory device is configured to store M-bit data, M being a positive integer equal to or greater than 2.

15. The memory device of claim 12, wherein the memory cell array includes a data area and a spare area, and wherein each of the memory cells in the data area stores M-bit data, and each of the memory cells in the spare area stores 1-bit data.

16. The memory device of claim 12, wherein the first error correction scheme is a high-speed error correction scheme that supports an on-the-fly function and the second error correction scheme is a high-performance error correction scheme that does not support the on-the-fly function.

17. The memory device of claim 12, wherein at least one of the first and second error correction schemes is an error correction scheme that uses a Bose-Chaudhuri-Hocquenghem (BCH) code.

18. The memory device of claim 12, wherein the memory cell array includes a data area and a spare area, and wherein input data is stored in the data area, and wherein the first ECC data and the second ECC data are stored in the spare area.

19. The memory device of claim 12, wherein the memory device is one of a NAND flash memory device, a NOR flash memory device, a phase change random access memory (PRAM) device or a magnetic random access memory (MRAM) device.