High Rate low pressure PECVD for barrier and optical coatings, Matthias Fahland, John Fahlteich, Björn Meyer, Steffen Straach, Nicolas Schiller
Outline Introduction PECVD New developments magpecvd arcpecv D Examples Optics Barrier Outlook
Plasma enhanced CVD PECVD? CVD chemical vapor deposition Layer growth by chemical reaction at surface Layer material delivered by chemical compound precursor Energy transforms precursor into reactive species Plasma energy is used within PECVD Several by-products H 2 O CO 2 other low-molecular compounds Additional reactive gas suppliable 3
Why PECVD? Low temperature process Use of sensitive substrates like polymers Performs in vacuum Clean environment Broad choice of pre cursors and reactive gases Wide range of process parameters Power Frequency Pressure... 4
Outline Introduction PECVD New developments magpecvd arcpecv D Examples Optics Barrier Outlook
Magnetron based PECVD magpecvd Low pressure CV D (0.3 3 Pa) Driven by pulsed DC magnetron High coating rates (up to 400 nm m/min) Proven long-term stability over 8 h 6
magpecvd W ell-established plasma source Proven feasibility for large area applications Tuneable layer composition 7
magpecvd DC sputtering One hardware dual magnetron targets gas inlets Two processes magpecvd reactive DC sputtering 8
Hollow-cathode arc PECVD arcpecvd Low pressure CV D (0.1 5 Pa) Driven by hollow cathode arc plasma Very high coating rates (> 2000 nm m/min) Tuneable layer composition Combination with evaporation possible Organic modified coatings 9
arcpecvd coating rates Linearly dependent from pre cursor flow Increase with plasma power Increase with additional reactive gas flow 10
Plasma syst em for arcpecvd Very high plasma density Commercially available Designed for production Any web width through numbers of plasma sources Developed for large area applications 2,85 m 11
arcpecvd Plasma enhanced evaporation One hardware hollow cathodes gas inlets Two processes arcpecvd Plasma enhanced reactive evaporation 12
Comparison of PECVD methods magpecvd arcpecv D HF-PECVD MW-PECVD typical frequency process pressure coating rates remarks 10-50 khz bipolar pulsed DC 13.56 MHz 2.45 GHz 0.3 3 Pa 0.1 5 Pa 1 20 Pa 5 100 Pa 20 400 nm m/min 500 3000 nm m/min industrially proven for wide webs, units commercially available 10 200 nm m/min 10 100 nm m/min pressure range different to PVD Low pressure CV D Inline combination with PVD possible 13
Inline combination of PECVD and PVD R&D and pilot roll coater at FEP 600 mm coating width Multi-chamber design Available processes Sputtering (planar / rotatable) magpecvd Evaporation arcpecv D 14
Outline Introduction PECVD New developments magpecvd arcpecv D Examples Optics Barrier Outlook
Layer composition Precursor to reactive gas ratio adjustable Layer composition tunable HMDSO ratio low low carbon content inorganic SiO 2 -like layers HMDSO ratio high higher carbon content organic SiO x C y H z layers 16
Layer composition mechanical properties Increase HM DSO ratio Decrease of hardness Decrease of elastic modulus Increase in flexibility 17
Optical performance
Dielectric solar control layer st acks overall thickness approx. 1400 nm SiO 2 made by infrared sputtering magpecvd 9 layers visible 19
Dielectric solar control layer st acks substrate curling due to layer stress nearly no layer stress 20
Dielectric UV-mirror with magpecvd 20 layers HfO 2 high refractive index 500 nm SiO 2 low refractive index high UV-reflectance high VIS-transmittance 21
Dielectric UV-mirror with magpecvd 20 layers Spectra measured across web width layer stack out of 20 single layers overall thickness approx. 1200 nm highly uniform over 400 mm web width only 12 nm UV-edge shift across web width 22
Permeation barrier
Permeation barrier stacks Covering of layer defects by upper layers Surface smoothing Annealing of permeation barrier defects Increase of barrier performance Increase of mechanical robustness 400 nm 24
Permeation barrier stacks Inline made barrier stack 2 m/min web speed High barrier level comparable to single layers Improved mechanical robustness 25 Barrier measurement @ 38 C, 90 % r.h. Sample size Ø100 mm
Permeation barrier st acks increased robustness Barrier layer Zinc-tin-oxid (ZTO) Interlayer SiO 2 made by magpecvd PECVD interlayers increase crack onset strain 1 2 3 number of ZTO layers Layer stack more robust against mechanical deformation 26
Summary PECVD within multi-chamber PVD coaters Low pressure PECV D Designed for easy scale up Two options: magpecvd and arcpecv D One hardware multiple processes Optical coating stacks with nearly no layer stress Permeation barrier stacks with increased mechanical robustness Further development work Qualification for further pre cursors Adaptation to further industrial applications... Your application? Where can we work together? How can PECVD technology be integrated into your facilities? 27
Acknowledgement Essential results were obtained in several public projects, funded by Free State of Saxony, Federal Ministry of Education and Research and European Union 28
Thank you for your attention for barrier and optical coatings Fraunhofer FEP Winterbergstr. 28 01277 Dresden Germany steffen.guenther@fep.fraunhofer.de www.fep.fraunhofer.de