Abstract

To understand the complicated physical and chemical processes that occur during the thin-film deposition process, diagnostics that are sensitive to suspected chemical species are necessary. Optical diagnostics are ideal because they are remote and nonintrusive. Several optical diagnostics have been applied to the plasma-assisted chemical vapor deposition (PACVD) process. Emission is often used for measurement of atomic species. The emission from excited atomic levels is often much larger than for excited molecular levels, so the atomic species dominate the emission spectra, and molecular signatures are difficult to extract. Species concentration is difficult to infer from plasma emission spectra because they generally involve excited electronic levels that are not in thermodynamic equilibrium with the ground state. An alternate diagnostic, sensitive to ground-state molecular species, is coherent antiStokes Raman scattering (CARS). CARS is a nonlinear optical technique useful for measuring the concentration and temperature of molecular constituents.

© 1988 Optical Society of America