Patent ID: 7408421

Claim:
A method for non-destructively determining a thermal absorption of a part of an integrated circuit, the method comprising: one of positioning a ring oscillator nearby the part or positioning the ring oscillator within the part, the ring oscillator including an inverter circuit, a non-silicided poly-silicon resistor coupled to an output of the inverter circuit, and a decoupling capacitor coupled between the output of the inverter circuit and a ground; measuring a delay of the ring oscillator when the integrated circuit is functioning; determining a resistance of the non-silicided poly-silicon resistor based on the delay of the ring oscillator; and determining the thermal absorption of the part of the integrated circuit based on the resistance of the non-silicided poly-silicon resistor; wherein parameters of the inverter circuit and the non-silicided poly-silicon resistor are tuned so that a delay of the ring oscillator varies predominantly with a variation in the resistance of the non-silicided poly-silicon resistor, the resistance primarily sensitive to the thermal absorption of the part.