Thin Films Technology. Lecture 3: Physical Vapor Deposition PVD. Jari Koskinen. Aalto University. Page 1

Thin Films Technology Lecture 3: Physical Vapor Deposition PVD Jari Koskinen Aalto University Page 1

Thin film deposition PVD Solid target Line of sight deposition Physical Low substrate temperature PECVD Reactive PVD CVD by sublimation CVD Liquid or gas precursor Global deposition Chemical High substrate temperature

Physical Vapour Deposition (PVD) Low energy PVD Thermal Evaporation - Electron beam - Resistive heating Molecular Beam Epitaxy (MBE) High Energy PVD Magnetron Sputtering (MS) - DC or RF - Balanced or Unbalanced Pulsed Laser Deposition (PLD) Cathodic arc - DC or pulsed - Filtered or un-filtered - With or without substrate bias High power impulse magnetron sputtering (HIPIMS)

PVD process Solid Target Ejected material Substrate for coating

PVD Plasma Plasma Colliding electrons ionise atoms Ions and electrons accelerate in electric field collisions excite atoms de-excitation creates photons visible light 5

Glow discharge http://astro-canada.ca

Glow discharge

DC Plasma glow discharge and arc 14

RF Plasma glow discharge 15 http://www.spectruma.de

RF Plasma glow discharge self bias 16 M. Ohring

Self bias at electrodes 4 Sivu 17

Energetic ion surface interactions 18

PVD coating process (High) vacuum long mean free path of ions high ion energy cleaning of surface desorption of gas sputtering of surface removal of oils water oxides 19

Average mean free path (distance between collission) in nitrogen residual gas <λ> Ultra Good High High Intermediate Rough Total pressure of residual gasses

Contents Plasma Ion surface interactions Film growth mechanisms Different PVD methods Commercial PVD coatings Scale up 21

Source materials Coating material from solid target or gas http://sunnygreater.com/products/sputtering_targets 22

Energetic ion and surface interactions collision cascade 10-14 10-13 s thermal spike 10-13 10-12 s Fast diffusion fast cooling relaxation 23 Jari Koskinen, Kts. Aalto simulaatio University 2016

Sputtering yield 24

Sputter yield and sublimation energy 25

Sputter yield angle dependence and energy distribution 26

Contents Plasma Ion surface interactions Film growth mechanisms Different PVD methods Commercial PVD coatings Scale up 29

PVD (Physical Vapour Deposition) Material from solid or gas Plasma Energetic ions hit surface Ions and neutrals grow the film https://www.yout ube.com/watch? v=lre5eqx9ofo www.iap.tuwien.ac.at/www/opt/images/parasol.jpg

PVD growth process Ion energy E i 10-1000 ev Surface temperature -190 C - 500 C (normally < 200 C) incidence angle Ion density Gas pressure Substrate surface 31 - Chemistry - Impurities - Topography

Competition of growing crystals Handbook of Deposition Technologies for Films and Coatings - Science, Applications and Technology (3rd Edition) Edited by: Martin, Peter M. 2010 William Andrew Publishing Sivu 32

Coating structure and plasma parameters slow hot fast cold 2/28/201 7 33

Modified Thorton diagram Sivu 34 A. Anders, Thin Solid Films 518 (2010) 4087 4090

Subplantation Sivu 35

Subplantation Sivu 36 Schematic diagram of densification by subplantation. A fraction of the incident ions penetrate the film and densify it, the remainder end up on the surface to give thickness growth.

Subplantation and experiments -Carbon Sivu 37

Subplantation Sivu 38

evolution of roughness Fig. 2. Schematic of roughness variation with film thickness in a general case. At first, the films consist of a series of islands where the new phase has nucleated, and the roughness increases quickly. Then the roughness peaks and decreases as the islands coalesce to form a closed, continuous film. The third stage consists of a constant roughness for epitaxial films. Finally, the roughness increases gradually above a roughening transition. The smoothness of tetrahedral amorphous carbon Diamond and Related Materials, Volume 14, Issues 3-7, March-July 2005, Pages 913-920 C. Casiraghi, A.C. Ferrari, J. Robertson

Stress Control Gas pressure /temperature Tensile stress due to collapsing of voids Higher temperature annealing of structure low stress Compressive stress subplantation 2/28/201 7 40

Compressive stress f FD = conc. of Frenkel defects f Ar = conc. of argon ΔΩ FD = volume change due to Frenkel defects ΔΩ Ar = volume change due to argon entrapped 2/28/201 7 41

Tensile stress 2/28/201 7 42

Ion beam nano roughening Enhanced adhesion 43