Gayatri Rane¹, Philipp Dürrenfeld¹, Uwe Krause², Denis Shaw^3
1Advanced Energy Industries Inc., Karlstein am Main, Germany
²Advanced Energy Industries Inc., Metzingen, Germany
¹Advanced Energy Industries Inc., Fort Collins, CO
Dual magnetron sputtering for reactive deposition of insulating materials is now a standard process in many industrial coating applications. Historically, AC power supplies with medium frequency sinusoidal generators have been extensively utilised to power the two targets alternatingly, but bipolar pulsed-dc power supplies, configured to change polarity with a 50/50 time share between the dual targets, can also enable dual magnetron sputtering, albeit with a more rectangular waveform.
It is known that the current/voltage waveforms affect the time-varying plasma properties such as ion and electron density. Thus, it is interesting to understand how these two power supply technologies influence the sputter process and the resulting coating properties when used on the same application.
In this work we compare the use of sinusoidal generator and bipolar pulsed-dc power supply in a silicon nitride/oxide process. For reliable comparability, the tests were carried out in an industrial sized drum coater with two 60 cm long Si targets under similar controlled process conditions. Impact of the two powering modes on the power normalised deposition rate, thermal heat load at the substrate, film stress and surface quality will be discussed. Optical emission spectroscopy with fast time resolution was utilised to understand the plasma behaviour differences. Further on, the findings have been corroborated by simulation studies, which will also be presented at the SVC Techcon (Large area coatings by Obrusnik et. al.).