Community Research and Development Information Service - CORDIS

Development of a novel hydrogen probe for plasma characterization and control during diamond film deposition

Measurements of the level of atomic hydrogen in a 13.56 MHz radio frequency plasma have been obtained during the deposition of diamond like carbon (DLC) films. 2 techniques were used, firstly a multiphoton laser induced fluorescence (MPLIF) system and secondly a novel combination of Langmuir probe and emission spectroscopy. In the latter technique the data obtained from electron energy distribution function (EEDF) measurements and hydrogen emission line intensities were combined using a computer modelling technique to give the atomic hydrogen concentration. This system can potentially be used as a portable atomic hydrogen probe. The results obtained were compared with those obtained using the MPLIF technique which in turn can be calibrated using a hydrogen transfer standard which is calibrated by a titration technique. The hydrogen probe technique gave similar relative increases to MPLIF, but the atomic hydrogen concentrations were approximately a factor of 4 higher. More accurate electron collision cross sections and EEDF measurements should produce better agreement. The 2 techniques have been used to measure atomic hydrogen, initially in a hydrogen plasma and subsequently in acetylene/hydrogen containing plasmas during the deposition of DLC films. In conjunction with these measurements in situ ellipsometry was used to obtain film thickness, refractive indices and extinction coefficients. A correlation has been obtained relating the concentration of atomic hydrogen with the insitu ellipsometry data for films with refractive index between 1.6 and 2.1 (at 675 nm).

Reported by

Ceramics Research Centre Glasnevin
9 Dublin
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