Nonvolatile semiconductor memory device

A method of determining condition of writing data utilizing a nonvolatile semiconductor memory device,

• the nonvolatile semiconductor memory device comprising:
• a memory cell array, the memory cell array including a plurality of first lines, a plurality of second lines configured to intersect the first lines, and a plurality of electrically rewritable memory cells disposed at each of intersections of the first lines and the second lines, each of the memory cells being configured from a variable resistor operative to store a resistance value of the variable resistor as data in a nonvolatile manner;
• a voltage supply circuit operative to apply a certain voltage to the memory cells via the first lines and the second lines during writing data to the memory cells or forming of the memory cells;
• a detection circuit operative to detect a change of the resistance value of the variable resistor in the memory cells during application of the certain voltage to the memory cells and output the detected change of the resistance value of the variable resistor as detection information;
• and
• an output circuit operative to output to external at least a portion of the detection information outputted from the detection circuit,
• the method of determining condition of writing data comprising:
• accumulating writing data time to the plurality of memory cells from the detection information;
• and
• determining an optimum value of the certain voltage applied to the memory cells from the voltage supply circuit based on the accumulated writing data time to the plurality of memory cells.

A method of writing data utilizing a nonvolatile semiconductor memory device,

• the nonvolatile semiconductor memory device comprising:
• a memory cell array, the memory cell array including a plurality of first lines, a plurality of second lines configured to intersect the first lines, and a plurality of electrically rewritable memory cells disposed at each of intersections of the first lines and the second lines, each of the memory cells being configured from a variable resistor operative to store a resistance value of the variable resistor as data in a nonvolatile manner;
• a voltage supply circuit operative to apply a certain voltage to the memory cells via the first lines and the second lines during writing data to the memory cells or forming of the memory cells;
• a detection circuit operative to detect a change of the resistance value of the variable resistor in the memory cell during application of the certain voltage to the memory cells and output the detected change of the resistance value of the variable resistor as detection information;
• and
• an output circuit operative to output to external at least a portion of the detection information outputted from the detection circuit,
• the method of writing data comprising:
• applying the certain voltage for writing data to the plurality of memory cells;
• judging whether or not writing data to the memory cells is complete by referring to the detection information;
• and
• if writing data to the memory cells is not complete, repeatedly changing voltage application conditions and performing rewrite until writing data to all of the memory cells is complete.