A method includes performing an operation on an electrically erasable programmable read-only memory (EEPROM) array. The operation is selected from a program operation and an erase operation. The EEPROM array includes EEPROM cells arranged in rows and columns, and a plurality of word-lines extending in a column direction. Each of the plurality of word-lines is connected to control gates of the EEPROM cells in a same column. The EEPROM array further includes a plurality of source-lines extending in a row direction. Each of the plurality of source-lines is connected to sources of the EEPROM cells in a same row. During the operation, a first source-line in the plurality of source-lines is applied with a first source-line voltage, and a second source-line in the plurality of source-lines is applied with a second source-line voltage different from the first source-line voltage.