Thickness measurement of multi-layer thin film alloy by X-ray fluorescence spectrometer

The Nickel-Vanadium (Ni-V) metal alloy, Silver (Ag) and Titanium (Ti) thin films are sputtered on the silicon die surface to increase the adhesion between Thermal Interface Material (TIM) and die during package assembly process [1]. However, the silver film will react and be consumed completely by TIM if the film thickness is too thin. The delamination or void defect will be induced between TIM and metal thin film interface at the same time. Hence, the metal thin film thickness must be monitored during process. The X-ray fluorescence spectrometer (XRF) is a widely used technology to measure metal thin film thickness and to analyze element composition. In general, the element composition ratio of alloy film must be acquired before thickness measurement. In this article, the XRF utilizes lower element composition ratio vanadium to analysis entire Ni-V alloy thickness and use general thin-film analysis method to establish the calibration curve and measure the metal thickness.