Development of a Microwave-Based Patch Antenna Sensor for Measuring Plasma Uniformit

Accurate and real-time measurement of electron density is critical for advancing semiconductor and display plasma processes in both current and next-generation technologies, as it directly impacts wafer quality and overall production yield. While microwave-based diagnostic techniques—such as the flat cutoff sensor—have been investigated, these typically necessitate a continuous coaxial structure or feature sensor bodies several millimeters thick, which limits their applicability. To address these constraints, we developed a Patch-Type Cutoff Sensor capable of transmitting microwaves and measuring plasma properties without relying on a coaxial configuration. The sensor's structure was refined using electromagnetic wave simulations, which also verified its accuracy across a range of plasma conditions. Furthermore, experimental validation confirmed the sensor's ability to probe bulk plasma characteristics. The effectiveness of this sensor in predicting wafer processing outcomes was further demonstrated by correlating its diagnostic outputs with actual etching results, underscoring its utility as a practical and compact diagnostic solution for semiconductor and display fabrication environments.