Method for evaluating semiconductor device
View Patent ↗To provide a simple method for evaluating reliability of a transistor, a simple test which correlates with a bias-temperature stress test (BT test) is performed instead of the BT test. Specifically, a gate current value is measured in the state where a voltage lower than the threshold voltage of an n-channel transistor whose channel region includes an oxide semiconductor is applied between a gate and a source of the transistor and a potential applied to a drain is higher than a potential applied to the gate. The evaluation of the gate current value can be simply performed compared to the case where the BT test is performed; for example, it takes short time to measure the gate current value. That is, reliability of a semiconductor device including the transistor can be easily evaluated.
1. A method for evaluating a semiconductor device, comprising the steps of:
measuring a gate current value in a state where a voltage lower than a threshold voltage of an n-channel transistor whose channel region comprises an oxide semiconductor is applied between a gate and a source of the transistor, and a potential applied to a drain is higher than a potential applied to the gate; and
evaluating reliability of the semiconductor device comprising the transistor, using the gate current value.
2. The method for evaluating a semiconductor device, according to claim 1 , wherein the voltage between the gate and the source of the transistor is negative.
3. The method for evaluating a semiconductor device, according to claim 1 , wherein the potential applied to the drain is zero.
4. A method for evaluating a semiconductor device, comprising the steps of:
measuring a variation in a gate current value with time in a state where a voltage lower than a threshold voltage of an n-channel transistor whose channel region comprises an oxide semiconductor is applied between a gate and a source of the transistor, and a potential applied to a drain is higher than a potential applied to the gate; and
evaluating reliability of the semiconductor device, comprising the transistor, using the variation in the gate current value with time.
5. The method for evaluating a semiconductor device, according to claim 4 , wherein the voltage between the gate and the source of the transistor is negative.
6. The method for evaluating a semiconductor device, according to claim 4 , wherein the potential applied to the drain is zero.