Production of dielectric filters with low defect levels for integrated optical devices

Abstract

We have assessed and reduced the particle count in coatings from a magnetron sputter coater used for production of optical coatings for applications in photonics and semiconductor industry. Results for particle levels in single layers from Al2O3, SiO2, Nb2O5, Ta2O5, and TiO2 showed semiconductor grade particle levels for the upgraded deposition system. Moreover, particle levels were also investigated for optical filter stacks deposited on bare Si, glass substrates and actual CMOS device wafers, which were used for the manufacturing of hyperspectral imaging (HSI) sensors. In all cases, low particle counts were detected in the optical filters as expected from the results obtained for the single layer. It could be shown that the coating on the device wafers had no negative impact on the production yield of the HSI sensors.