| 摘要 |
PURPOSE: A method for operating a semiconductor device is provided to improve the reliability of program and read operations by suppressing the change of a threshold voltage of memory cells in a program operation. CONSTITUTION: One memory cell block is selected among memory cell blocks according to a program command. A pre-program operation and a pre-erase operation are performed to distribute a threshold voltage of the memory cells of the selected memory cell block between a first voltage of a positive type and a second voltage of a negative type(502). A program allowing voltage is applied to the selected bit lines of the selected memory cell block and a program inhabitation voltage is applied to the unselected bit lines of the selected memory cell block(505). A positive program voltage is applied to a word line connected to the selected memory cells. [Reference numerals] (502) First step of transmitting a threshold voltage of a selected memory cell to a reference voltage; (503) Second step of programming a fourth state or third state programmed cell with the third state; (504) Third step of erasing a second state or first state erased cell with the second state; (505) Fourth step of programming cells of a second step with a fourth state; (506) Fifth step of erasing cells of a third step with a first state; (AA) Start; (BB) Finish |
