Patent ID: 9213592
Filing Date: 2015-12-15
Classification: G06F,G11C

Abstract:
1. A method of performing a refresh operation of a semiconductor memory device, the method comprising: reading data stored in memory cells of a page; performing an error correction loop (ECC loop) comprising: performing an error checking and correcting operation (ECC) on the read data; determining a number of bit errors in the read data; and when the number of bit errors is greater than a maximum number of correctable bits, incrementing an ECC count and changing the maximum number of correctable bits by increasing the maximum number of correctable bits, and repeating the ECC loop by performing the error checking and correcting operation using the changed maximum number of correctable bits; storing the ECC count when the number of bit errors in the read data is less than the maximum number of correctable bits as a result of performing the ECC; and programming corrected data to the memory cells when the stored ECC count is more than a preset number.