Patent ID: 11894074
Assignee: KIOXIA CORPORATION
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 0:
1. A semiconductor memory device comprising:
a plurality of memory cell transistors each capable of storing a plurality of bits of data, a threshold voltage of each of the memory cell transistors being included in one of a plurality of states, the states including a first state and a second state, the second state being higher than the first state, a memory cell transistor whose threshold voltage is included in the first state storing first data, and a memory cell transistor whose threshold voltage is included in the second state storing second data;
a word line coupled to the memory cell transistors; and
a controller configured to perform a write operation that includes a plurality of program loops each including a program operation and a verify operation,
wherein
a verify low voltage and a verify high voltage higher than the verify low voltage are set for each of the states, and
in a verify operation of the first data, during application of a verify high voltage of the first data to the word line, the controller determines whether or not a threshold voltage of a memory cell transistor to which the first data is to be written exceeds the verify high voltage of the first data, and also determine whether or not a threshold voltage of a memory cell transistor to which the second data is to be written exceeds a verify low voltage of the second data.