Short courses 

The short courses will take place on Monday, June 14, 2021  from 9:00 - 14:00 and will consist of the following:

Ionized physical vapor deposition and related technologies

This course is intended for students, engineers, technicians, and others interested in plasma-assisted deposition of thin film and functional coatings. A good portion of the course is dedicated to introduce and review the basics of low-temperature plasmas and discharges to produce them. While gas plasmas are often used, emphasis is put on discharges that lead to ionization of plasma with condensable species: metal or metal-containing plasmas, leading to coatings from the plasma phase. In contrast to many other courses, the role of plasmas and sheaths will be clearly distinguished and explained. This distinction is will be appreciated when examples of processes with plasmas are given, including but not limited to plasmas made by ion plating, filtered cathodic arcs and by high power impulse magnetron sputtering (HiPIMS). After over a decade of research, HiPIMS has become an industrially used extension of sputtering technology. With sputtered metals ionized, the texture of coatings can be tuned by energetic condensation even when substrates are kept near room temperature. Recent developments of HiPIMS will be discussed, including reactive HiPIMS and so-called “hybrid technology” where one of the components is HiPIMS.

Understanding and control of stress in thin films

Thin films produced by PVD techniques are usually under a stressed state, due to the mechanical constraint imposed by the substrate. Several factors are affecting the resulting stress state, which can be either tensile or compressive, with magnitude up to several GPa. The understanding and control of stress development in thin films is essential, especially for nanoscale systems, to ensure device integrity.

The course will start with a description of residual stress sources in PVD thin films, with main focus placed on intrinsic stress. Stress evolutions during film growth and post-deposition treatments will be presented, and the underlying atomistic and microscopic mechanisms discussed. Experimental assessment of stress in thin films will be reviewed, based on recent advances in optical and X-ray diffraction techniques, allowing a depth-sensitive determination as well as real-time diagnostics. Examples will be given for polycrystalline and amorphous thin films, as well as multilayered systems. The influence of microstructure (grain size, texture) and deposition process parameters on the stress development in PVD hard coatings will be outlined. The role of energetic species involved during magnetron sputtering or ion-beam assisted deposition, on the compressive stress build-up will be highlighted. Finally, strategies to control stress and stress engineering for specific applications will be proposed.

  • Origin of residual stress in PVD thin films
  • Stress and strain: elasticity theory
  • Surface and interface stress effects in thin films
  • Coherence stress- Epitaxial growth
  • Experimental determination from wafer-curvature and X-ray diffraction methods and their limitations
  • Intrinsic stress evolution during polycrystalline film growth
  • Factors (working pressure, temperature, growth rate, ion bombardment…) affecting intrinsic stress
  • Selected examples of stress evolution during metal, nitride or oxide film growth
  • Stress engineering and applications

Short Course C:

Optical properties of meta-materials and meta-surfaces: Fundamentals and practical issues

Structuration of the matter at the nano-scale offers unprecedented flexibility for controlling and manipulating light, by giving for instance access to near-zero or negative index of refraction or by allowing the design of new planar optical components. The optical properties of these artificial components (called meta-materials or meta-surfaces for respectively three-dimensional or two-dimensional structures) are derived both from the inherent properties of their constitutive elements as well as the geometrical arrangement of these elements at a scale smaller than or similar to the wavelength of the optical field. 

This course begins by some fundamentals on the optical properties of dielectrics and metals, and by some recalls on the mathematical definition of the refractive index and the requirements imposed to this quantity by causality constraint and dissipation condition. The complex admittance formalism is then used to describe the optical properties of different types of metamaterials such as fishnet structures, metal-dielectric multilayer stacks or epsilon-near-zero material. We place particular emphasis on the description of some recent examples of achievement, as well as a detailed analysis of the pro and con of three different characterization methods respectively based on the measurement of a spatial shift (near field approach), an angular deviation (far field approach) or a phase delay (interferometric approach). Furthermore, the physical mechanisms required to design efficient all-dielectric meta-surfaces is analyzed and this approach is illustrated through various examples.

This course should enable you to:

  • Understand the physical mechanisms that drive the optical properties of these nano-structured materials;
  • Identify the potential applications of these entirely new structures, but also some of their main limitations.