Improved Uniformity of Photoresist Ashing for a Half-Inch Wafer with Double U-shaped Antenna Structure in a Microwave-Excited Water Vapor Plasma

In this study, the uniformity of a photoresist ashing for a half-inch wafer was improved by a developed antenna structure, a double U-shaped antenna, in microwave-excited water vapor plasma. The optimized double U-shaped antenna structure, obtained by simulating an electric field, generated a spread distribution microwave plasma. Experimentally obtained results demonstrate that the observed optical emission distribution image from the microwave plasma resembles the electric field distribution obtained from the simulation under the present water vapor plasma generation condition. The double U-shaped antenna showed a higher ashing rate and better uniformity than the conventional slot antenna.