| 摘要 |
A simulator for accurately simulating the degree of degradation and the degree of recovery of a characteristic of a transistor so as to design a semiconductor device with high reliability. A method for the simulation is also disclosed. If a negative gate voltage (negative bias voltage) Vg is applied to the gate of a transistor, the characteristics of the transistor will degrade. When the application of the negative gate voltage Vg is ceased (namely, when a bias-free voltage is applied), the degraded characteristics of the transistor will recover. Taking a log of the application time t of the gate voltage, log(t), and using constants CD, BD dependent on the negative bias voltage, the degree of degradation Delta PD(t)=CD+BD.log(t) is calculated. Using constants CR, BR dependent on the bias-free voltage, the degree of recovery DeltaPR(t)=CR+BR.log(t) is calculated. The degree of degradation (DeltaPD), the degree of recovery (DeltaPR), and the fundamental degradation (XD) are summed. Preferably, by dividing the passage time into time divisions and using a degradation function and a recovery function different every time division, the degree of degradation and the degree of recovery for each time division are determined.
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