Vapor deposited thin organic–inorganic capping layers preventing copper line oxidation in polymer-based RDL technologies

Hybrid organic–inorganic and inorganic multilayer films were deposited using a combination of CVD and ALD processes to develop an ultra-thin barrier to prevent copper oxidation in a polymer-based RDL technology. ALD layers are known to be effective permeation barriers due to their uniformity and pinhole-free morphology. However, the low deposition temperature, required by the presence of polymers in the final product, increases their susceptibility to degradation by water. In this study, polymer-embedded copper lines protected by ultra-thin vapor deposited cappings, processed at temperatures below or equal to 100 °C, were exposed to oxidation and corrosion stress tests for more than 1000 h. Above an inorganic layer critical thickness of 5 nm, copper oxidation is fully blocked. In addition, it is demonstrated that some of these ultra-thin layers can withstand a corrosion stress test paving the road for their integration in polymer-based RDL technologies.