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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2010 > Séminaires 2010 > Le jeudi 18 novembre à 11 heures

Le jeudi 18 novembre à 11 heures

Anurag Mishra-Time-resolved diagnostic study of HiPIMS processes

Le jeudi 18 novembre à 11 heures
Salle de conférence du LIX

HiPIMS (High Power Impulse Magnetron Sputtering) is a relatively new highly ionised sputtering technique used to deposit engineering quality thin films, with the advantage that the deposition flux can be guided to the substrate through the electrical biasing. As the technique is on the verge of being adopted by the industries, it is necessary to understand its physics very well so that thin films with tailored properties can be deposited. Therefore, time-resolved diagnostic studies have been carried out to get better physical insight of the HiPIMS processes.
Ion energy distribution function (IEDF) is an important discharge parameter, responsible for the properties of deposited thin films. Therefore, a technique to get IEDF with very high temporal resolution (1 µs) has been developed for the HiPIMS discharges. The excellent agreement between the summation of all the time-resolved IEDFs at different times during the pulse and a time-averaged IEDF recorded by mass spectrometer demonstrated that this technique is quite suitable for very high time-resolved measurements of IEDFs in the HiPIMS discharges.
Plasma potential (VP) is crucial parameter that determines the plasma dynamics. Therefore, using an emissive probe the temporal evolution of VP has been investigated in the HiPIMS discharge pulsed at 100 Hz. The 20 ns time-resolution of the probe allowed us to observe the highly dynamic nature of Vp. The emissive probe results show that for over 50 % of the 100 µs plasma “on-time” the spatial structure of Vp provides a large potential barrier for the sputtered ionised species so impeding their transport and lowering the deposition at the substrate.
The experiments were also carried out to investigate how the deposition rates in HiPIMS, DC and pulsed DC magnetron discharges depend upon the magnetic field strength of the magnetron. A deposition rate monitor has been used to measure the deposition rate at four magnetic field strengths. For HiPIMS discharges, the results show that the deposition rate increases by a factor of 2 as the magnetic field strength at the cathode is reduced by only 45%. However, in DC and pulsed DC discharges the deposition rates decreased by 35% for the same reduction in the magnetic field strength.
A simple computational model of the sputter rates based on the voltage and current waveforms and energy dependent sputter yields predicts decreasing deposition rates for reduced B-fields, in-line with the DC and pulsed DC mode results. However, it shows the opposite trends to the measurements in the HiPIMS mode. This discrepancy between predicted and experiment for HiPIMS has been explained on the basis that the transport of the post-ionised sputtered atoms, which form the deposit, are affected by the potential structure in the discharge, itself modified by the magnetic field strength.


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Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
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Exploitant du site : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Hébergeur : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Directeur de la publication : Pascal Chabert (Directeur)