Eddy current measurement of tungsten thin film thickness on silicon wafers

Tungsten is widely utilized in the fabrication of metal interconnects for integrated circuits, making the precise thickness of its thin films a critical parameter for ensuring process quality. To address the need for accurate measurement of tungsten thin film thickness on silicon wafers, this paper presents a non-contact measurement system based on the eddy current principle. Through an optimized sensor design, the system's measurement sensitivity has been significantly enhanced. Experimental validation was performed by depositing tungsten films of various thicknesses on silicon wafers via magnetron sputtering and conducting multiple sets of repeated measurements. The results demonstrate a strong positive correlation and excellent linearity between the film thickness and the sensor's output voltage. The system achieves a relative measurement error of less than 3% for tungsten thin film thickness on silicon wafers. It successfully meets the requirements of the IC manufacturing industry, offering robust metrological support for the metal interconnect process.