The development of thin film metrology by coherence scanning interferometry

Scanning White Light Interferometry (SWLI), now referred to as Coherence Scanning Interferometry (CSI), is established as a powerful tool for sub-nanometer surface metrology. The technique provides accurate and rapid three dimensional topographical analysis without contacting the surface under measurement. This paper will focus on recent developments of CSI using the Helical Complex Field (HCF) function that have extended its use for important thin film measurements. These developments now enable CSI to perform thin film thickness measurements, to measure the surface pro fi le and the interfacial surface roughness of a buried interface and to derive optical constants (index of refraction n and extinction coefficient kappa).