Industrial-scale PECVD processing of encapsulation layers for temperature- and water-sensitive electronic devices
(Room Room 104-A)
02 May 19
4:20 PM
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4:40 PM
Tracks:
Plasma Processing
Pinhole-free, electrically insulating and sometimes transparent barriers for (opto-)electronic devices operating under atmospheric or even more humid conditions are recently of increasing demand. Often, the combination of these properties must be achieved with low process temperatures if the degradation of sensitive electronic device materials shall be avoided. In this presentation, silicon nitride (a-SixNy:H) coatings obtained with the plasma-enhanced chemical vapor deposition technique in the dual frequency (microwave (MW, 2.45 GHz) / radio frequency (RF, 13.6 MHz)) mode are discussed. Such dual mode plasma sources have recently been implemented in our large-area, high-throughput inline tools based on Meyer Burger’s MAiA® platform allowing for the cost-efficient deposition of pinhole-free, hard, well-grafting and transparent coatings at temperatures < 100 °C. In short, the use of linear microwave antenna arrays in a non-stationary set-up provides a high plasma density and allows for deposition rates > 2 nm/s and for a high coating uniformity in an area of up to 1500 mm x 1000 mm. The additional use of the RF excitation, on the other hand, allows for an adjustment of the ion energy in between about 0 eV and more than 100 eV. The use of high kinetic energies provides densification and smoothing of near-stoichiometric silicon nitride films at low temperatures as well as a superior grafting of these films on plastics, organics and epoxy resins as well as on copper and tin alloys (peel strength > 1 N/cm2). Printed circuit boards coated in this way exhibit breakdown voltages above 20V/µm in salty water which is a proof of the excellent encapsulation properties of these PECVD layers. These industrial-scale < 300nm thick coatings meet with Water Vapour Transmission Rates WVTR < 10-5 g/m2/day the requirements as electrically insulating and transparent moisture barriers. In combination with organic interlayers WVTR < 10-6 g/m2/day are achieved. In the final paper the encapsulation of organic electronic devices as OLEDs and OFETs as well as the future packaging solutions for the consumer electronics industry are discussed.