Methods for predicting reliability of semiconductor devices using voltage stressing

A method for evaluating a failure rate of semiconductor wafers containing a plurality of semiconductor devices, comprising:

• selecting a semiconductor wafer for testing, wherein each semiconductor device in the selected semiconductor wafer is capable of being tested for measuring a critical parameter that indicates failure of associated semiconductor device;
• for each of the semiconductor devices in the selected semiconductor wafer,
• measuring the associated critical parameter under a normal operating voltage for the semiconductor devices;
• applying an elevated voltage above the normal operating voltage to each of the semiconductor devices for a specified period of time;
• and
• measuring the associated critical parameter after applying the elevated voltage;
• and
• comparing the measured critical parameters to obtain a failure result when the critical parameter measured after applying the elevated voltage is not approximately equal to the critical parameter measured before applying the elevated voltage;
• and
• determining a failure rate for the selected semiconductor wafer from the failure results of the associated semiconductor devices, wherein the failure rate indicates a probability of failure for the selected semiconductor wafer.

A method for evaluating a failure rate of a wafer lot having a set of semiconductor wafers, each semiconductor wafer containing a plurality of semiconductor devices, the method comprising:

• for each semiconductor wafer in the wafer lot,
• selecting a semiconductor wafer for testing, wherein each semiconductor device in the selected semiconductor wafer is capable of being tested for measuring a critical parameter that indicates failure of associated semiconductor device;
• and
• for each of the semiconductor devices in the selected semiconductor wafer,
• measuring the associated critical parameter under a normal operating voltage for the semiconductor devices;
• applying an elevated voltage above the normal operating voltage to each of the semiconductor devices for a specified period of time;
• measuring the associated critical parameter after applying the elevated voltage;
• comparing the measured critical parameters to obtain a failure result when the critical parameter measured after applying the elevated voltage is not approximately equal to the critical parameter measured before applying the elevated voltage;
• and
• determining a failure rate for the associated semiconductor wafer from the failure results of the semiconductor devices, wherein the failure rate indicates a probability of failure for the associated semiconductor wafer;
• and
• determining an overall failure rate for the wafer lot from the failure rate of the semiconductor wafers, wherein the overall failure rate indicates a probability of failure for the entire wafer lot.