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.