Atomic fluorine densities in electron beam generated plasmas: A high ion to radical ratio source for etching with atomic level precision
Abstract
Electron beam generated plasmas are generally characterized by a high plasma density (>1010 cm−3), and very low electron temperatures (<1 eV), making them well-suited for next generation processing techniques where high fluxes of low energy ions are desirable. In addition, both modeling and optical emission spectroscopy indicate relatively low concentrations of atomic radicals compared to discharges. Due to their relevance to industrial etching applications, this work focuses on the characteristics of electron beam generated plasmas produced in fluorine-containing chemistries (SF6, CF4, F2), with particular attention paid to atomic fluorine densities. Atomic F* emission is measured in Ar/SF6, Ar/CF4, and Ar/F2 mixtures and the Ar 750 nm/F 704 nm line ratios are then used to calculate the F atom densities as a function of reactive gas concentration, the first radical density measurement in this type of plasma to date. These results are compared with F atom density calculations performed using a zero dimensional non-local thermodynamic equilibrium Boltzmann code for Ar/SF6 and Ar/F2 mixtures to understand and verify the line ratio analysis. Good agreement between modeling and measurements points to a uniquely high ion-to-atomic radical density in electron beam generated plasmas.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 06, 2016
- Source ID
- 10.1116/1.4971416
Entities
People
- David R. Boris
- G. M. Petrov
- Scott G. Walton
- Tzvetelina Petrova
Organizations
- United States Naval Research Laboratory