Plasma characterisation in high power pulsed magnetron sputtering

• In this thesis, plasma parameters including plasma and floating potentials, electron energy distribution function (EEDF) plasma density and electron temperature are studied in a high power pulsed magnetron (HPPM) discharge at different Argon (Ar) gas pressures and different magnetron powers. It is reported that the EEDF during and shortly after the pulse can be represented by a bi-Maxwellian distribution indicating two energy groups of electrons.Furthermore, we report on the variation of the plasma parameters and electron energy distribution function with gas pressure in the pressure range 0.5-20 mtorr. At a high pressure (> 10 mTorr) two density peaks are present, the second of which occurs hundreds of microseconds after the pulse is switched off. It shows that the second peaks occurrence depends on the target material used as well as the chamber pressure and the magnetron power. It is found that the electron density is very high (up to 1019 m-3, during the whole of the measured 2000 µs, indicating the importance of the second density peak in maintaining the high plasma density.Measurements on the electron temperature show that this does not exceed 3 eV while the pulse is on, and that it is no more than 0.5 after the pulse is off. A movie is constructed using Langmuir probe measurements data, showing the temporal evolution of the plasma at 20 mTorr argon pressure and 11 J pulse energy. Analysis shows the existence of a magnetic trap underneath the center of the target. Furthermore, the electron flux in the substrate vicinity 10 - 12 cm from the target is found to be homogeneous. Ti thin films are grown along the sidewalls of a hole, 1 cm2 in area and 2 cm in depth, using both de magnetron and HPPM sputtering. Secondary electron microscopy shows that the film grown by de magnetron sputtering shows clear columnar growth, while a dense and flat film was produced using the HPPM sputtering technique.

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NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

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