Microwave discharge enables the production of high-density (≥1017 m-3) large-area (≥5 m2) flat plasma, owing to its efficient absorption of surface waves. To irradiate microwaves over an entire plasma surface uniformly, an array of slotted waveguide antennas combined with a novel compact power divider is developed. A general guideline for designing the slot antenna array for desired plasma dimensions is presented. Furthermore, in accordance with the antenna design optimized by finite difference time domain (FDTD) simulation, a 915 MHz microwave plasma of 1.3 ×1.1 m2 area was successfully produced, verifying the plasma uniformity with two-dimensional Langmuir probe measurements.

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