Patent ID: 7898277

Claim:
A method of hot-carrier injection screening a plurality of wafers, the method comprising: a) selecting one wafer from the plurality of wafers, each wafer having a plurality of MOSFETs thereon and each of the MOSFETs having at least a gate, a drain, and a threshold voltage; b) selecting one of the plurality of MOSFETs on the selected wafer; c) applying a gate test voltage to the gate of the selected MOSFET and a drain test voltage to the drain of the selected MOSFET and measuring an initial current flow in the drain of the selected MOSFET; d) applying, during a stress time period, a gate stress voltage to the gate of the selected MOSFET and a drain stress voltage to the drain of the selected MOSFET; e) applying, at a time subsequent to the stress time period, the gate test voltage to the gate and the drain test voltage to the drain of the selected MOSFET and measuring a test current flow in the drain of the selected MOSFET; f) adjusting at least one of the gate and drain stress voltages if the test current flow differs from the initial current flow by an amount that is outside of a desired range; g) repeating steps c) through f) with another MOSFET selected from the plurality of MOSFETs until the test current flow differs from the initial current flow by an amount that is within the desired range; and h) hot-carrier injection testing at least one of the remaining wafers of the plurality of wafers using the stress voltages determined in steps c) through g); wherein the drain test voltage is less than the threshold voltage.