Semiconductor storage device

A semiconductor storage device comprising:

• a plurality of local source lines extending in a first direction;
• a plurality of local bit lines extending in a second direction crossing the first direction;
• a plurality of memory cells, each connected between one of the local source lines and one of the local bit lines and including a switching element and a variable resistance element;
• and
• a read circuit configured to perform a read operation on a memory cell by:
• applying voltages to one of the local source lines and one of the local bit lines to select the memory cell,
• switching the selected memory cell to an ON state,
• performing a first read operation on the selected memory cell that has been switched on the ON state,
• generating a first voltage based on the first read operation,
• switching the selected memory cell to the ON state after first data is written to the selected memory cell on which the first read operation has been performed,
• performing a second read operation while maintaining the selected memory cell in the ON state when the first data is stored in the selected memory cell during the first read operation,
• performing the second read operation after the selected memory cell transitions from the ON state to an OFF state at least once when second data different from the first data is stored in the selected memory cell during the first read operation,
• generating a second voltage based on the second read operation, and
• determining the data stored in the selected memory cell during the first read operation based on the first voltage and the second voltage.

A method of performing a read operation on a memory cell of a semiconductor storage device, the memory cell including a switching element and a variable resistance element, said method comprising:

• switching the memory cell to an ON state;
• performing a first read operation on the memory cell that has been switched to the ON state;
• generating a first voltage based on the first read operation;
• after the first read operation, performing a write operation on the memory cell to write first data into the memory cell;
• switching the memory cell to the ON state after the first data is written to the memory cell on which the first read operation has been performed;
• performing a second read operation while maintaining the memory cell in the ON state when the first data is stored in the memory cell during the first read operation;
• performing the second read operation after the memory cell transitions from the ON state to an OFF state at least once when second data different from the first data is stored in the memory cell during the first read operation;
• generating a second voltage based on the second read operation;
• and
• determining the data stored in the memory cell during the first read operation based on the first voltage and the second voltage.