The neutral charge counter fragments of F and H atoms were concurrently generated through mechanisms of dissociation. CH 2F + via bond dissociation of C-H or C-F. Two channels are involved in the ionization pathway produced for the CHF 2 + and CH 2F + ions. The measurements obtained from positive ion mass spectrometry indicate that CHF 2 + and CH 2F + are the dominant positive ions. ![]() Mass Spectrometric Measurements of Positive Ions A Kr or Ar gas mixture with CH 2F 2 gas was introduced into the reaction chamber, and the electrode was applied with very high frequency (VHF) power to preserve the plasma. To ensure accurate processing, species balance for deposition and etching is closely related and essential to the dissociation reactions in gas-phase.Ī dual frequency capacitively coupled plasma (CCP) etching reactor was used in the experiment, and a quadrupole mass spectrometer (QMS) was installed on the wall of the chamber. Dissociation of the C-F bond results in F atoms, which are a main etchant for Silicon (Si), whereas dissociation of the C-H bond produces H atoms, which allow polymers to be deposited on the substrate surface. Reactions of interest involving bonds between C-F and C-H are vital for density control of the reactive species. Hydroflurocarbons have H atoms present, instead of the F atoms in flurorcarbon gases. Individual CH 2F + and CHF 2 + ion fraction on total CH xF y + ion density at Kr- and Ar-diluted CH 2F 2 plasma. According to the analytical results, adding Kr or Ar to CH 2F 2 plasmas provided some measure of control over the fraction densities of the CHF 2 + and CH 2F + ions (Figure 2).įigure 2. ![]() Cross section for dissociative ionization for a CH 2F 2 molecule.įor plasmas diluted with Kr the appearance energy of C-H was due to the predomination of CHF 2 + ions, with a similar charge exchange channel for collisions between CH 2F 2 and Kr+. In plasmas diluted with Ar, the predomination of CH 2F + ions was due to the dissociative ionization between the appearance energy of C-F and Ar + (Figure 1).įigure 1. The ion densities of CHF 2 + and CH 2F + were estimated using pathways of dissociative ionization, within charge exchange channels of collision in CH 2F 2 plasmas. The analysis of rare gas (M) diluted CH 2F 2 plasma using quadrupole mass-spectroscopy (QMS) has shown specific formation of CHF 2 + ion for dilution of krypton (Kr) and CH 2F + ion for dilution of argon (Ar). Sponsored by Hiden Analytical Mar 22 2016
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