Interfacial Reactions Between Sputtered Cr-Sio2 Cermet Thin Film and Polyimide

Interfacial chemical bonding states between polyimides (PI) and sputter coated Cr-SiO2 thin film have been investigated mainly by XPS to obtain a reliability basis for thin film resistor application of Cr-SiO2.We tried to leave different level of etch residue by applying two etchants of different etching power, then analyzed the etched surfaces by XPS, TEM and EXAFS. It proved that at first Cr in the sputtered Cr-SiO2 reacts with oxygen atoms which were introduced during O2 plasma treatment of the PI surface and also with original carbonyl oxygen of the PI to offer Cr-O-C bond at the Cr-SiO2/PI interface. This was concluded from the attenuation of Cls peak intensity corresponding to the carbonyl group. Then after thermal annealing, Cr extracted most of the interface oxygen to give a Cr2O3 layer of a discrete thickness. These phenomena were supported by TEM and SR-EXAFS as well.