US Patent 7733706 Flash memory device and erase method thereof

A flash memory device and an erase method thereof are included. The erase method includes performing an erase operation of a memory cell block including a plurality of pages, performing an erase verify operation and storing unerased page information about a page including unerased memory cells that have not been normally erased, and performing an additional erase operation of the page including the unerased memory cells based on the unerased page information. When the unerased memory cells exist, the erase verify operation and the additional erase operation are performed repeatedly.