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U. Schmid, A. Ababneh, H. Seidel, R. Wagner, K. Bauer:
"Characterization of Aluminium Nitride and Aluminium Oxide Thin Films Sputter-Deposited On Organic Substrates";
Microsystem Technologies - Micro- and Nanosystems - Information Storage and Processing Systems, Vol. 14 (2008), 4-5; 483 - 490.

In microsystems technology, passivation layers
are generally required to protect micro devices and functional
elements against environmental impact, particularly
against corrosion, thus increasing reliability and lifetime to
acceptable values. In this work, the use of sputter-deposited
aluminium oxide and aluminium nitride thin films on
flexible polyimide foils was investigated, aiming at the
protection of flow sensitive elements. Due to a high defect
density located at the interface between the passivation
layer and the organic substrate, the adhesion of pure aluminium
oxide thin films was found to be poor when
applying a combination of mechanical stress (e.g. bombardment
with water droplets) and thermal cycling as an
accelerated ageing procedure. A bi-layer consisting of
aluminium nitride and aluminium oxide, however, shows a
defect-free interface to the organic substrate resulting in an
enhanced adhesion. In addition, no structural failure can be
detected after applying the aging procedure, making this
bi-layer approach well suited for the targeted application.

http://dx.doi.org/10.1007/s00542-007-0434-x