OPERATING METHOD FOR MEMORY SYSTEM INCLUDING NONVOLATILE RAM AND NAND FLASH MEMORY
First Claim
1. An operating method for a memory system including a nonvolatile random access memory (NVRAM) and a NAND flash memory, the method comprising:
- receiving a read request directed to a target memory cell of the NAND flash memory;
performing a normal read operation directed to the target memory cell in response to the read request; and
then,determining that a read fail has occurred as a result of the normal read operation; and
then in response to the read fail,performing a read retry operation by iterations directed to the target memory cell according to a first read retry scheme until a pass read retry iteration successfully reads the target memory cell; and
then,storing pass information associated with the pass read retry iteration in the NVRAM.
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Accused Products
Abstract
An operating method for a memory system including a nonvolatile random access memory (NVRAM) and a NAND flash memory includes; performing a normal read operation directed to the target memory cell in response to a read request, determining that a read fail has occurred as a result of the normal read operation, then performing a read retry operation by iterations directed to the target memory cell according to a first read retry scheme until a pass read retry iteration successfully reads the target memory cell, and storing pass information associated with the pass read retry iteration in the NVRAM.
238 Citations
20 Claims
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1. An operating method for a memory system including a nonvolatile random access memory (NVRAM) and a NAND flash memory, the method comprising:
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receiving a read request directed to a target memory cell of the NAND flash memory; performing a normal read operation directed to the target memory cell in response to the read request; and
then,determining that a read fail has occurred as a result of the normal read operation; and
then in response to the read fail,performing a read retry operation by iterations directed to the target memory cell according to a first read retry scheme until a pass read retry iteration successfully reads the target memory cell; and
then,storing pass information associated with the pass read retry iteration in the NVRAM. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An operating method for a memory system including a nonvolatile random access memory (NVRAM) and a NAND flash memory, the method comprising:
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receiving a read request directed to a target memory cell of the NAND flash memory; determining whether a number of program/erase (P/E) cycles for the target memory cell has reached a reference value; and (A) upon determining that the number of P/E cycles for the target memory cell has not reached the reference value, performing a first normal read operation with default voltages directed to the target memory cell;
else(B) upon determining that the number of P/E cycles for the target memory cell has reached the reference value, reading pass information related to the read request previously stored in the NVRAM, and performing a second normal read operation with adjusted voltages by read pass information directed to the target memory cell; and
then,determining that a read fail has occurred as a result of the first or second normal read operation; and
then in response to the read fail,performing a read retry operation by iterations directed to the target memory cell until a pass read retry iteration successfully reads the target memory cell; and
then,storing updated pass information associated with the pass read retry iteration in the NVRAM. - View Dependent Claims (12, 13, 14)
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15. An operating method for a memory system including a nonvolatile random access memory (NVRAM) and a NAND flash memory, the method comprising:
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receiving a read request directed to a target memory cell of the NAND flash memory; performing a normal read operation directed to the target memory cell in response to the read request; and
then,determining that a read fail has occurred as a result of the normal read operation; and
then in response to the read fail,iteratively performing an read operation using different read voltages to obtain pass information; making a soft decision regarding the programmed state of the target memory cell in relation to the pass information; and storing the pass information in the NVRAM. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification