On mass- and emission spectroscopic CVD process monitoring of organometallics/O2 discharges

Mass spectroscopic analysis of neutrals and ions from a deposition plasma shows that the decomposition of the organometallic precursor compounds [La(thd)₃, Cu(acac)₂, and Al isopropoxide] in the plasma .starts with the abstraction of complete ligands. The mass spectra of plasma ions sensitively indicate the incomplete oxidation of the organic fragments with increasing organometallic partial pressure. The concentration of carbon-rich ions in the oxygen-based deposition plasma correlates with the carbon content of the deposited oxide films. Specific emissions of the precursor compounds (e.g., Cu atomic lines and LaO bands) can be used to monitor the precursor partial pressure; however, there is some interference with sputter emission from the deposited films. During La₂O₃ deposition, optical emission of oxidation products (e.g., OH, CO, CO₂ bands) was used to regulate the precursor partial pressure in the discharge with a closed-loop control circuit.On leave from Friedrich Schiller University, Institute of Physical Chemistry, Lessingstrasse 10, D-O-6900 Jena, Germany.On leave from California State University, Department of Chemistry, 2555 East San Ramon Avenue, Fresno, California 93740-0070.