Time resolved Langmuir probe characterisation of reactive pulse magnetron sputtering of mgo thin films

A time resolved Langmuir double probe technique is presented which is applied to a pulsed magnetron discharge at several hundred kilohertz used for MgO deposition. The probe was positioned on the symmetry axis of tire circular magnetron. The time resolved measurement leas done by fixing the probe voltage and recording the probe current as a function of time. This was repeated for different voltages. Then, the matrix of the I-U(t) curves was transposed with a computer to yield the usual I(U) characteristic for each tune step, from which the plasma density and electron temperature were determined. After proper correction of the measured I-u(t) curves, consistent results are obtained. In particular, a characteristic time dependence of the charge carrier density during the `pulse on' time including a sequence of maximum and minimum values was found. This characteristic temporal evolution of the charge carrier density depends on the pulse frequency cold duty cycle. Similar structures in the electron temperature are only observed when the probe is placed near the magnesium target. (C) 2004 IoM Communications Ltd. Published by Maney for the Institute of Materials, Minerals and Mining.