Abstract
Capacitively coupled nitrogen plasma discharges driven by two different exciting radio frequencies of 13.56 MHz, and 40 MHz are investigated. Langmuir probe diagnostics along with optical emission spectroscopy are used for interpreting the discharges. The results of these diagnostics are not shown sufficiently in the literature for 40 MHz even though there are some for 13.56 MHz. The electron density ne and the effective electron temperature Teff are calculated from the measurements of the current – voltage characteristics of the discharges. These calculated parameters are correlated with the vibrational temperatures of the N2 second positive system C3Πu−B3Πg and the N2+ first negative system B2Σu+−X2Σg+ measured via optical emission spectroscopy. The population of the vibrational excitation particles plays a crucial role in the determination of the vibrational temperature which strongly depends on ne and Teff. The transition from collisionless stochastic heating mode to collisional Ohmic heating mode into the bulk plasma appears at lower pressure value for 40 MHz as compared to 13.56 MHz. This effect is observed effectively with increasing the RF input power due to the high energy electrons. It is noted that the vibrational temperatures of N2 and N2+ decreases at high-pressure region (>0.3 Torr for 13.56 MHz and >0.2 Torr for 40 MHz) due to a reduction in the relative population of the vibrationally excited particle. The measurements of the Langmuir probe are very consistent with the results of the optical emission spectroscopy.
Highlights
Various plasma techniques including the radio frequency (RF) discharge, microwave (MW) discharge, and dielectric barrier discharge (DBD) are commonly used for many applications such as surface etching, surface modifications, and film deposition.1–5 Among these techniques, RF plasma discharge has more controllable ion and electron densities which provides an easy control on the chemistry during the plasma processing
The capacitively coupled RF plasma discharge is commonly used in many types of processing,7–11 and it has some mode transitions by varying the RF power as well as the gas pressure
To understand the mechanisms of the discharges observed during the processes, it very crucial to determine the plasma diagnostics such as the electron temperature, the plasma density, and the electron energy distribution function (EEDF)
Summary
Various plasma techniques including the radio frequency (RF) discharge, microwave (MW) discharge, and dielectric barrier discharge (DBD) are commonly used for many applications such as surface etching, surface modifications, and film deposition. Among these techniques, RF plasma discharge has more controllable ion and electron densities which provides an easy control on the chemistry during the plasma processing. Various plasma techniques including the radio frequency (RF) discharge, microwave (MW) discharge, and dielectric barrier discharge (DBD) are commonly used for many applications such as surface etching, surface modifications, and film deposition.1–5 Among these techniques, RF plasma discharge has more controllable ion and electron densities which provides an easy control on the chemistry during the plasma processing. The capacitively coupled RF plasma discharge is commonly used in many types of processing, and it has some mode transitions by varying the RF power as well as the gas pressure. To understand the mechanisms of the discharges observed during the processes, it very crucial to determine the plasma diagnostics such as the electron temperature, the plasma density, and the electron energy distribution function (EEDF).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.