Measurement of Plasma Density Using a Electrode Sensor on Wafer in an Inductively Coupled Plasma and Comparison with Other Diagnostic Methods

In advanced semiconductor manufacturing processes, increasing device integration demands ultra-fine processing and improved yield. To meet these requirements, precise control of plasma processes has become increasingly important, particularly with regard to measuring plasma density, which is a key parameter. Currently, the Langmuir probe is widely used for plasma density measurements. However, this method involves inserting the probe directly into the plasma, which causes plasma perturbation, thereby limiting the accuracy and reproducibility of the measurements.



In this study, we employed a electrode sensor on wafer, which minimizes plasma perturbation by integrating the sensor into the wafer itself. The sensor was installed inside an Inductively Coupled Plasma(ICP) chamber, and argon gas was used as the process gas. Plasma was generated by varying the process pressure and applied Radio Frequency(RF) power. Using the electrode sensor on wafer, plasma density was measured directly on the substrate surface and compared with measurements obtained using a single Langmuir probe.