Abstract
Although the recently developed cutoff probe is a promising tool to precisely infer plasma electron density by measuring the cutoff frequency () in the S spectrum, it is currently only applicable to low-pressure plasma diagnostics below several torr. To improve the cutoff probe, this paper proposes a novel method to measure the crossing frequency (), which is applicable to high-pressure plasma diagnostics where the conventional method does not operate. Here, is the frequency where the S spectra in vacuum and plasma conditions cross each other. This paper demonstrates the method through three-dimensional electromagnetic wave simulation as well as experiments in a capacitively coupled plasma source. Results demonstrate that the method operates well at high pressure (several tens of torr) as well as low pressure. In addition, through circuit model analysis, a method to estimate electron density from is discussed. It is believed that the proposed method expands the operating range of the cutoff probe and thus contributes to its further development.
Highlights
Composed of physically energetic charged particles and chemically reactive neutral particles, plasma has been widely used in various fields including material fabrication and nuclear fusion as well as medical, environmental, and aerospace industries [1,2]
For plasma deposition in particular, plasma sputtering, plasma-enhanced chemical vapor deposition (PECVD), and plasma-enhanced atomic layer deposition (PEALD) approaches have been widely used for their high deposition rates, low-temperature processing, good film conformality, and high film uniformity [12,13,17,18]
If the sheath width is unknown, by using Equation (3), the electron density can be estimated with a theoretical discrepancy of about 10%
Summary
Composed of physically energetic charged particles and chemically reactive neutral particles, plasma has been widely used in various fields including material fabrication and nuclear fusion as well as medical, environmental, and aerospace industries [1,2]. These days, such an approach seems illsuited since the current challenges in cutting-edge material fabrication involve processing steps that abruptly increase and involve complicated chemistries [1,3,4,12,13] To overcome this limitation, two alternatives have been proposed, namely computer simulation and plasma internal parameter diagnostic methods [20]. Simulation is at present applicable to specific processes using simple chemistries The latter, referring to methods that find the optimum process window based on internal plasma parameters, has attracted great interest in industrial as well as academic fields since plasma has an influence on most chemical reactions contributing to the deposition process [25–28]. Applied the CP to a fluorocarbon film deposition process (
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
