Jones Alami

Ion-assisted physical vapor deposition for enhanced film properties on nonflat surfaces

We have synthesized Ta thin films on Si substrates placed along a wall of a 2-cm-deep and 1-cm-wide trench, using both a mostly neutral Ta flux by conventional dc magnetron sputtering (dcMS) and a mostly ionized Ta flux by high-power pulsed magnetron sputtering (HPPMS). Structure of the grown films was evaluated by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The Ta thin film grown by HPPMS has a smooth surface and a dense crystalline structure with grains oriented perpendicular to the substrate surface, whereas the film grown by dcMS exhibits a rough surface, pores between the grains, and an inclined columnar structure. The improved homogeneity achieved by HPPMS is a direct consequence of the high ion fraction of sputtered species.

Ionization of sputtered metals in high power pulsed magnetron sputtering

The ion to neutral ratio of the sputtered material have been studied for high power pulsed magnetron sputtering and compared with a continuous direct current (dc) discharge using the same experimen ...

Spatial and temporal behavior of the plasma parameters in a pulsed magnetron discharge

We demonstrate the evolution of the electron, energy distribution and the plasma parameters in a high-density plasma in a pulsed magnetron discharge. The high-density plasma is created by applying ...

Evolution of the electron energy distribution and plasma parameters in a pulsed magnetron discharge

We demonstrate the creation of high-density plasma in a pulsed magnetron discharge. A 2.4 MW pulse, 100 μs wide, with a repetition frequency of 50 Hz is applied to a planar magnetron discharge to study the temporal behavior of the plasma parameters: the electron energy distribution function, the electron density, and the average electron energy. The electron density in the vicinity of the substrate, 20 cm below the cathode target, peaks at 8×1017 m−3, 127 μs after initiating the pulse. Towards the end of the pulse two energy groups of electrons are present with a corresponding peak in average electron energy. With the disapperance of the high-energy electron group, the electron density peaks, and the electron energy distribution appears to be Maxwellian like. Following the electron density peak, the plasma becomes more Druyvesteyn like with a higher average electron energy.

Low temperature deposition of α-Al2O3 thin films by sputtering using a Cr2O3 template

A description about low temperature deposition of a-Al2O3 thin films by sputtering was presented. Cr2O3 thin layer was used as a template. Nanoindentation was used to study the mechanical propertie ...

Plasma dynamics in a highly ionized pulsed magnetron discharge

We report on electrostatic probe measurements of a high-power pulsed magnetron discharge. Space- and time-dependent characteristics of the plasma parameters are obtained as functions of the process parameters. By applying high-power pulses (peak power of ~0.5 MW), with a pulse-on time of ~100 µs and a repetition frequency of 20 ms, peak electron densities of the order of ~1019 m− 3, i.e. three orders of magnitude higher than for a conventional dc magnetron discharge, are achieved soon after the pulse is switched on. At high sputtering gas pressures (>5 mTorr), a second peak occurs in the electron density curve, hundreds of microseconds after the pulse is switched off. This second peak is mainly due to an ion acoustic wave in the plasma, reflecting off the chamber walls. This is concluded from the time delay between the two peaks in the electron and ion saturation currents, which is shown to be dependent on the chamber dimensions and the sputtering gas composition. Finally, the electron temperature is determined, initially very high but decreasing rapidly as the pulse is turned off. The reduction seen in the electron temperature, close to the etched area of the cathode, is due to cooling by the sputtered metal atoms.

X-ray reciprocal space mapping studies of strain relaxation in thin SiGe layers (≤ 100 nm) using a low temperature growth step

Relaxation of thin SiGe layers (~90 nm) grown by molecular beam epitaxy using a low temperature growth step (120-200°C) has been investigated using two-dimensional reciprocal space mapping of X-ray diffraction. The samples studied have been divided in two groups, depending on the substrate cooling process during the growth of the low temperature layer. It has been found that a higher degree of relaxation was easily achieved for the sample group without growth interruption. A process window for full relaxation of the Si0.74Ge0.26 layer has been observed in the range of 140-150°C.

Measurement of the magnetic field change in a pulsed high current magnetron discharge

In this paper we present a study of how the magnetic field of a circular planar magnetron is affected when it is exposed to a pulsed high current discharge. Spatially resolved magnetic field measur ...

Ion-acoustic solitary waves in a high power pulsed magnetron sputtering discharge

We report on the creation and propagation of ion-acoustic solitary waves in a high power pulsed magnetron sputtering discharge. A dense localized plasma is created by applying high energy pulses (4–12 J) of length ≈70 µs, at a repetition frequency of 50 pulses per second, to a planar magnetron sputtering source. The temporal behaviour of the electron density, measured by a Langmuir probe, shows solitary waves travelling away from the magnetron target. The velocity of the waves depends on the gas pressure but is roughly independent of the pulse energy.