| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a program voltage deciding method for a nonvolatile memory in which variance of threshold voltage of a memory cell after programming by injection of hot carriers can be suppressed. <P>SOLUTION: This method includes: a step in which a drain voltage is set to a prescribed voltage; a program step in which the drain voltage and a prescribed gate voltage are applied at a prescribed programming time; a change step in which the setting voltage of the drain voltage is changed; a reprogram step in which the program step is carried out with the drain voltage after changing the setting voltage; a measuring step in which a threshold voltage after programming is measured; and a detection step in which a differential value expressed by the ratio of change quantity of the threshold voltage to change quantity of the drain voltage in the threshold voltage after the reprogram step is detected. When both of the detected differential value and the measured threshold voltage are in the prescribed allowable range, changed drain voltage is decided as an optimum value. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
