A hybrid surface cavity microwave source with a capacitively coupled plasma for plasma uniformity control

CCP discharges have emerged as the workhorse technology in a wide variety of applications, including fabrication of nano-devices with very stringent requirements. CCP discharges are traditionally electrostatically driven, but recent very high-frequency (VHF) operation has magnified the importance of the physics of coupling of electromagnetic waves in the plasma. Such coupling is still poorly understood despite nearly two decades of research in this area. This is mainly due to the scarcity of space and time-resolved experimental measurements of key variables, and unresolved physics representation in computational models of very high frequency capacitively coupled plasmas (VHF-CCP). In this study, common problems with CCP discharge uniformity will be highlighted using argon plasma under different system pressures. Furthermore, certain additions to the CCP geometry are investigated to observe its effects on its domain. For example, the addition of a vane type structure along with the electrode adds further tunable paramenters, improves electric field and plasma coupling. The addition of this surface wave cavity can make traditional CCP’s scalable which allows large-scale domains. However, the scattered nature of the electric field in the waveguide and, by extension, the CCP gas domain may result in heavily varying species densities.