Role of neutral molecule chemistry in electron cyclotron resonance microwave plasmas capable of diamond deposition

Abstract

The chemical compositions of 4% carbon in hydrogen/deuterium electron cyclotron resonance (ECR) microwave plasmas based on ethane, ethylene, acetylene, and methane, as determined by supersonic pulse, plasma sampling mass spectrometry, have been kinetically modeled using only a steady-state concentration of hydrogen to represent the role of the plasma. Using 375 isotopically labeled chemical steps based on 54 reversible neutral molecule chemical reactions, simulated spectra were generated that matched all eight experimental spectra using only literature values of the kinetic and energetic constants and three physically reasonable fitted parameters that were held constant for all eight simulations. The success of the modeling provides strong evidence that the chemistry of ECR-microwave plasmas is dominated by neutral molecule reactions.

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

“…Mass spectrometry (MS) and some of its variants: molecular beam mass spectrometry (MBMS), neutral mass spectrometry (NMS), and also the energy‐resolved mass spectrometry (ERMS) were successfully employed . In theoretical approach, several models were developed, for example, one‐dimensional fluid models of pure acetylene plasma and a model where plasma was replaced with a steady‐state concentration of atomic hydrogen and only neutral molecule chemistry was considered …”

“…Methane and acetylene ECR discharges are an object of very long and intense attention, because of their applicability for preparation of carbon based thin films such as diamond like carbon (DLC), diamond, carbon nitride (CNx), TiC, carbon nanoparticles, carbon nanosheets, carbon nanowalls (CNWs), and nanotubes (CNTs) . DLC films are interesting for numerous industrial and biomedical applications .…”

“…The quantity of acetylene ions is rather high in the range of power up to 350 W, but it drops down with increasing power. At 24 Methane and acetylene ECR discharges are an object of very long and intense attention, because of their applicability for preparation of carbon based thin films such as diamond like carbon (DLC), [1][2][3][4][5][6][7][8][9] diamond, [10] carbon nitride (CNx), [11] TiC, [12] carbon nanoparticles, [13] carbon nanosheets, [14] carbon nanowalls (CNWs), [15] and nanotubes (CNTs). [16,17] DLC films are interesting for numerous industrial and biomedical applications.…”

“…[2,4,12,24,28,34,36] In theoretical approach, several models were developed, for example, one-dimensional fluid models of pure acetylene plasma [34,35] and a model where plasma was replaced with a steady-state concentration of atomic hydrogen and only neutral molecule chemistry was considered. [10] 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.…”