Evaluation of an end feed microwave cavity plasma source for diamond etching

Summary form only given. Advances in the deposition of diamond films over the last decade have necessitated tools for diamond film post-processing. An end feed microwave cavity etcher shows promising performance for the radial and azimuthally uniform etching of diamond under a wide range of processing conditions. The performance of two end feed microwave cavity sources have been characterized. The first was a 17.8 cm diameter cavity with 13 cm discharge. Input power levels tested ranged from 100 W to 600 W with argon between 1 and 45 mtorr. Performance of this source was evaluated with and without a discharge magnetic field by measuring charge density, ion production cost, and electron temperature. This source showed stable and repeatable performance over a wide range of operating parameters. For many conditions charge densities in excess of 10¹² cm^-3 could be attained. Results of this study also demonstrated that removing magnetic fields above the pressure of 10 mtorr could significantly increase discharge density. The second end feed cavity source tested was of similar design, but with a larger 30 cm diameter cavity and 24 cm diameter discharge. The power input range for this source was also larger: from 200 W to 1500 W. A 13.56 MHz biasable pedestal (able to hold 15 cm wafers) was present in this discharge chamber, with bias power up to 300 W available. Discharge parameters, diamond etch rates, and etch rate uniformities were measured for a range of discharge conditions. The internally tuned stable high and low pressure operation of this source makes it advantageous for a wide range of future applications in plasma generation. High pressure operation facilitates high etch rates needed for thick diamond film processing. Low pressure operation is critical for anisotropic etching of high aspect ratio structures found in microelectronic circuits and MEMS