OPTICAL-EMISSION SPECTROSCOPY ON PULSED-DC PLASMAS USED FOR TIN DEPOSITIONS

The plasma-assisted chemical vapour deposition process in a large-scal e industrial plant for coating of TIN on tool steels was investigated by optical emission spectroscopy. Several atomic lines and molecular b ands were identified. A parametric study of the dependence of bias vol tage, total pressure and gas flows, H-2, N-2, Ar and TiCl4, on the pla sma characteristics was performed to gain understanding of the influen ce of the parameters on the deposition process. With the change of pro cess parameters, large variations in the emitted light, corresponding to changes in plasma conditions, were observed. In the parameter range studied, the deposition rate depends linearly on the N-2(+) signal wh en varying the pressure and the N-2 flow, whereas no clear correlation between the OES signal and the deposition rate could be found for var iations of the other parameters. (C) 1998 Elsevier Science S.A.