Towards ultra-precise optical interference filters on large area:computational and experimental optimization of the homogeneity ofmagnetron-sputtered precision optical coatings

摘要

The optimization of the uniformity of high precision optical filters is often a critical and time consuming procedure. Thegoal of the present paper is to evaluate critical factors that influence the thickness distribution on substrates during amagnetron sputter process. A new developed sputter coater “EOSS” was used to deposit SiOsub2/sub and Nbsub2/subOsub5/sub single films andoptical filters. It is based on dynamic deposition using a rotating turntable. Two sets of cylindrical double magnetrons areused for the low and the high index layers, respectively. In contrast to common planar magnetrons, the use of cylindricalmagnetrons should yield a more stable distribution during the lifetime of the target. The thickness distribution on thesubstrates was measured by optical methods. Homogenization is carried out by shaping apertures. The distribution of theparticle flow from the cylindrical magnetron was simulated using particle-in-cell Monte Carlo plasma simulationdeveloped at Fraunhofer IST. Thickness profiles of the low index and the high index layers are calculated by numericalsimulation and will be compared with the experimental data. Experimental factors such as wobbling of the magnetronduring rotation, geometrical changes of critical components of the coater such as uniformity shapers as well as gas flowvariations will be evaluated and discussed.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.