| 摘要 |
<p>PROBLEM TO BE SOLVED: To apply a relieving treatment when the leak current is small by estimating the maximum current value which can be relieved by self-convergence treatment and obtains a reference current value based on the charge pump current supplying capacity inside and outside the device and comparing this current value with the leak current. SOLUTION: The maximum current value Imax estimated based on the charge pump current feeding capacity is set in a reference cell 9 by using the maximum current value Id0 in the processable range of selfconvergence with reference to the drain voltage dependence. At the time of reading to the memory cell, the drain voltage is impressed to obtain the leak current Id2, and the current values, Id0 and Id2, are compared by a sense amplifier 1. When the leak current value Id2 is greater, it is judged that the charge pump cannot relieve the over-erased memory cell, which is regarded as a defective product. Memory cells are successively replaced in the memory cell 8 to judge the possibility of relief and accordingly the inspecting time is reduced to reduce cost.</p> |
