A Detailed Investigation of Radicals and Ions in ECR Methane/Argon Microwave Discharge

Abstract

In this work, we focus on study of the formation and behavior of molecules, radicals, and ions in ECR discharge in a mixture of argon and methane. Discharge properties are studied at various conditions; total gas flow (0-50 sccm), absorbed microwave power (0-900 W) and the partial pressure of methane (0-1.2 Pa). Neutral mass spectrometry does not reveal the presence of radical CH 5 commonly described in literature. Spectra show the presence of atomic hydrogen H and especially H 2 molecules. The number of CH 4 þ and CH 3 þ species shows that the amount of CH 4 þ in areas power up to 350 W is high, but with further increase of the power their amount decreases. With the increasing power the CH 3 þ ions are more intensively generated. The obtained data helps optimize process conditions for the fabrication of diamond and DLC thin films.

Creation and behavior of radicals and ions in the Acetylene/Argon microwave ECR discharge

“…However, against expectation, a study of ECR discharge in acetylene/argon performed at microwave power of 200–300 W and pressure of 0.13–0.65 Pa has not reported, the presence of polymerized ions, that is, C 3 H y , C 4 H y . On the other hand, our results of analyses of methane/argon ECR discharge revealed presence of relatively high amount of polymerized ions (C 2 H y and C 3 H y ) . Hence, we should expect their appearance also in acetylene/argon ECR discharge.…”

“…DLC films are interesting for numerous industrial and biomedical applications . In some cases, a combination with RF discharge is used for DLC film fabrication . However, ECR microwave plasma deposition has finally asserted itself as the most efficient method.…”

“…In the present publication, we have focused on investigation of the processes in ECR acetylene plasma. This study is a part of a comprehensive detailed investigation of the behavior of gaseous hydrocarbons in ECR discharges in our institution . The goal of our research is to find optimum conditions for formation of carbon thin films by comparing ECR discharges in CH 4 /Ar or C 2 H 2 /Ar.…”

“…Mass spectrometry of neutral molecules and radicals in the plasma requires the input of a part of a gaseous sample into the orifice of the mass spectrometer (MS), subsequent ionization of these particles, their mass separation, and final detection. This method requires multi‐stage pumping (three‐step) of the mass spectrometer with several orifices (a shutter of 10 mm in diameter between the second and third stage was used), so that it would be possible to distinguish and separate the neutrals from the plasma . This makes it possible to determine the composition of neutrals, radicals, their transmutations, and as the case may be, the chemical reactions taking place in the working chamber without or with a discharge.…”

“…The equipment used for studying the properties of radicals and ions is the same as in the methane/argon case, and is described in detail in ref . The pumping stand is provided with a turbomolecular pump at a pumping rate of 150 l/s down to the ultimate pressure p 0 = 7.5 × 10 −4 Pa.…”