Structural and Electrical Methods for Enhancing Homogeneity in Intermediate Pressure Capacitively Coupled Plasma Processing Sources

Capacitively coupled plasma manufacturing processes are ubiquitous in semiconductor fabrication pipelines where control of the radial plasma density profile is key to maintaining the resulting etch or deposition quality. Developing a detailed understanding of the physics mechanisms that underpin spatial uniformity control, driven for example by the structure of the electrode profile and the shape of the driving voltage waveform, is critical as substrate sizes increase. In this work, self-consistent 2D fluid/Monte-Carlo simulations are employed to study the effects of introducing structures into the electrodes of a capacitively coupled argon plasma operating at 1 Torr in argon. The improvements to uniformity that are achieved by changing the physical structure of the electrode are compared with the distinct technique of applying 'tailored' waveform driving voltages, formed through the superposition of 5 harmonics of 13.56 MHz with a variable phase offset. Continued enhancement of radial uniformity in plasma-assisted manufacturing reactors enables higher fidelity outputs in existing infrastructure, and presents the capability to maintain current processing quality with increased substrate diameters in next-generation sources.