Patent ID: 9627085
Date: 2017-04-18
CPC Classifications: G06F,G11C

Claim:
1. A refresh method for a flash memory, comprising: performing a write operation to store an input data into a storage space in the flash memory, the write operation comprising an initial program operation, a first reprogram operation, and a second reprogram operation which are sequentially performed; checking reliability of the storage space with the input data already stored therein, the checking step comprising: detecting if the storage space with the input data already stored therein suffers from data-retention disturbance; and when the checking steps indicates that the storage space suffers from the data-retention disturbance, performing a refresh operation upon the storage space based on the input data, and the refresh operation comprises: wherein the input data stored in the storage space by the write operation is read based on a first initial setting of reference threshold voltage values, and the input data stored in the storage space by the refresh operation is read based on a second initial setting of reference threshold voltage values different from the first initial setting of reference threshold voltage values; the second initial setting of reference threshold voltage values corresponds to threshold voltage distributions that are sharper than threshold voltage distributions of the first initial setting of reference threshold voltage values.