| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a method for soft-programming a floating-gate memory cell. SOLUTION: A substrate and a source 11 are connected at reference voltage, and a control gate 13 is supplied with soft-programming voltage within a range to 60% from 30% of voltage for hard-programming a memory cell. A current flowing into a drain 12 is monitored while applying increasing voltage to the drain, and specific drain voltage the same as or smaller than a drain voltage value at a time when the current reaches a first peak is selected. The substrate is set at reference voltage, the drain is supplied with first voltage the same as or slightly smaller than the above-mentioned specific drain voltage, the source is fed with positive second voltage smaller than the above-mentioned specific drain voltage, and a control gate is fed with third voltage not made larger than the above-mentioned soft programming voltage, thus soft-programming the cell.</p> |
