Thermal Interface Metrology Using Periodic Heating for Buried Rth

The patent applies periodic heating to the sample and measures temperature oscillations at different depths. By using periodic action at specific frequencies, the thermal waves penetrate to different depths, enabling selective measurement of deeply buried interfaces. The periodic heating creates measurable temperature oscillations that propagate through the stack, allowing extraction of interfacial thermal resistance at buried interfaces without requiring direct access to the interface location.

The patent changes the frequency parameter of the periodic heating to control thermal penetration depth. By varying the heating frequency, different depths within the semiconductor stack can be probed. This parameter change enables the measurement system to selectively target deeply buried interfaces while maintaining a relatively simple measurement setup, resolving the contradiction between measurement precision and device complexity.

By using periodic heating instead of steady-state heating, the patent creates oscillating temperature fields that maintain larger temperature amplitudes at depth compared to steady-state conditions. The periodic action prevents thermal equilibrium, allowing temperature oscillations to be detected even at deeply buried interfaces where the absolute temperature jump would be very small in steady-state measurements.

The patent employs thermal vibration through periodic heating, creating oscillating temperature fields that propagate through the semiconductor stack. This thermal vibration approach amplifies the detectable signal at buried interfaces by maintaining dynamic temperature oscillations rather than relying on small static temperature differences, thereby improving both reliability and measurement precision simultaneously.