Using AlN-Coated Heat Sink to Improve the Heat Dissipation of LED Packages

In magnetized capacitively coupled radio-frequency discharges operated at low pressure the inﬂuence of the magnetic ﬂux density on discharge properties has been studied recently both by experimental investigations and in simulations. It was found that the Magnetic Asymmetry Eﬀect allows for a control of the DC self-bias and the ion energy distribution by tuning the magnetic ﬁeld strength. In this study, we focus on experimental investigations of the electron power absorption dynamics in the presence of a magnetron-like magnetic ﬁeld conﬁguration in a low pressure capacitive RF discharge operated in argon. Phase Resolved Optical Emission Spectroscopy measurements provide insights into the electron dynamics on a nanosecond-timescale. The magnetic ﬂux density and the neutral gas pressure are found to strongly alter these dynamics. For speciﬁc conditions energetic electrons are eﬃciently trapped by the magnetic ﬁeld in a region close to the powered electrode, serving as the target surface. Depending on the magnetic ﬁeld strength an electric ﬁeld reversal is observed that leads to a further acceleration of electrons during the sheath collapse. These ﬁndings are supported by 2-dimensional Particle in Cell simulations that yield deeper insights into the discharge dynamics.

Section: Introductionmentioning

confidence: 99%

Electron dynamics in planar radio frequency magnetron plasmas: III. Comparison of experimental investigations of power absorption dynamics to simulation results

Berger

Eremin

Oberberg

et al. 2023

“…The deposition of thin films is a key procedure for many applications in modern industry [15,40]. A wide range of different technological fields relies on it: for instance, high quality thin films are needed for optical components, microelectronics and medical applications [29,41,56,66]. An important and commonly used thin film deposition process is physical vapor deposition (PVD) [53].…”

Section: Introductionmentioning

confidence: 99%

The magnetic asymmetry effect in geometrically asymmetric capacitively coupled radio frequency discharges operated in Ar/O₂

Oberberg

Berger

Buschheuer

et al. 2020

Previous studies in low pressure magnetized capacitively coupled radio frequency (RF) plasmas operated in argon with optimized geometric reactor symmetry have shown that the magnetic asymmetry effect (MAE) allows to control the particle flux energy distributions at the electrodes, the plasma symmetry, and the DC self-bias voltage by tuning the magnetron-like magnetic field adjacent to one electrode (Oberberg et al 2019 Plasma Sources Sci. Technol. 28 115021; Oberberg et al 2018 Plasma Sources Sci. Technol. 27 105018). In this way non-linear electron resonance heating (NERH) induced via the self-excitation of the plasma series resonance (PSR) was also found to be controllable. Such plasma sources are frequently used for reactive RF magnetron sputtering, but the discharge conditions used for such applications are significantly different compared to those studied previously. A high DC self-bias voltage (generated via a geometric reactor asymmetry) is required to realize a sufficiently high ion bombardment energy at the target electrode and a reactive gas must be added to deposit ceramic compound layers. Thus in this work, the MAE is investigated experimentally in a geometrically asymmetric capacitively coupled RF discharge driven at 13.56 MHz and operated in mixtures of argon and oxygen. The DC self-bias, the symmetry parameter, the time resolved RF current, the plasma density, and the mean ion energy at the grounded electrode are measured as a function of the driving voltage amplitude and the magnetic field at the powered electrode. Results obtained in pure argon discharges are compared to measurements performed in argon with reactive gas admixture. The results reveal a dominance of the geometrical over the magnetic asymmetry. The DC self-bias voltage as well as the symmetry parameter are found to be only weakly influenced by a change of the magnetic field compared to previous results obtained in a geometrically more symmetric reactor. Nevertheless, the magnetic field is found to provide the opportunity to control NERH magnetically also in geometrically asymmetric reactors. Adding oxygen does not alter these discharge properties significantly compared to a pure argon discharge.

“…hard coatings or optical filters. In the microelectronic industry, thin films are deployed as insulator, heat sinking or masking material for plasma etching [3][4][5]. Even for medical applications antibacterial and biocompatible coatings are synthesized and explored [6].…”

Section: Introductionmentioning

confidence: 99%

Ion energy control via the electrical asymmetry effect to tune coating properties in reactive radio frequency sputtering

Ries

Banko

Hans

et al. 2019

A knowledge-based understanding of the plasma-surface-interaction with the aim to precisely control (reactive) sputtering processes for the deposition of thin films with tailored and reproducible properties is highly desired for industrial applications. In order to understand the effect of plasma parameter variations on the film properties, a single plasma parameter needs to be varied, while all other process and plasma parameters should remain constant. In this work, we use the Electrical Asymmetry Effect in a multi-frequency capacitively coupled plasma to control the ion energy at the substrate without affecting the ion-to-growth flux ratio by adjusting the relative phase between two consecutive driving harmonics and their voltage amplitudes. Measurements of the ion energy distribution function and ion flux at the substrate by a retarding field energy analyzer combined with the determined deposition rate R d for a reactive Ar/N2 (8:1) plasma at 0.5 Pa show a possible variation of the mean ion energy at the substrate E m ig within a range of 38 and 81 eV that allows the modification of the film characteristics at the grounded electrode, when changing the relative phase shift θ between the applied voltage frequencies, while the ion-to-growth flux ratio Γig/Γgr can be kept constant. AlN thin films are deposited and exhibit an increase in compressive film stress from −5.8 to −8.4 GPa as well as an increase in elastic modulus from 175 to 224 GPa as a function of the mean ion energy. Moreover, a transition from the preferential orientation (002) at low ion energies to the (100), (101) and (110) orientations at higher ion energies is observed. In this way, the effects of the ion energy on the growing film are identified, while other process relevant parameters remain unchanged.