| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the number of threshold value measuring times by measuring a threshold of a transistor while exponentially increasing a cumulative value of a voltage application time between a gate/a drain at every threshold measurement. SOLUTION: A pulse with a fixed time width t0 and prescribed voltages 12V, 5.5V is used for a memory cell becoming the measurement object of the threshold Vt of the transistor as the voltage between the gate/drain, and the cumulative value of the number of pulses at every threshold Vt measurement is increased exponentially. Concretely, after the number of pulses '1' is added, first threshold measurement is performed (cumulative write-in time = T0 ), and further, after the number of pulses '1' is added, second threshold measurement is performed (cumulative write-in time = 2.t0 ). Further, after the number of pulse '2' is added, third threshold measurement is performed (cumulative write-in time = 4.t0 ), and successively, after the number of pulse '4' is added, fourth threshold measurement is performed (cumulative write-in time = 8.t0 ).</p> |
