| 摘要 |
PROBLEM TO BE SOLVED: To obtain a semiconductor memory device in which an error correction can be executed easily and precisely by a constitution wherein, as compared with a probability that a first transition in which a state that an electric charge is stored in a charge storage layer is shifted to a state that the electric charge is pulled out is generated, a probability that a second transition in which a state that an electric charge is pulled out is shifted to a state that the electric charge is stored is small and the logical sum of respective corresponding bits is computed. SOLUTION: In a read operation, a data train of 16 values is constituted of respective bits which are read out from memory cells M1 to M4, and they are corrected uniformly. As compared with a probability that a state '0' in which electrons are pullsed out is shifted to a state '1' in which the electrons stored in the floating gate electrode of every memory cell, a probability that a state '0' is shifted to a state '1' in which the electrons are pulled out is very small. In addition, a probability that the respective bits stored in two memory cells among from the four memory cells M1 to M4 are changed erroneously and a probability that the state '1' in which the two or more bits in the data string are shifted to the state '0' from the state '1' are small, and an error in the data string can be corrected. |
