What if I can not find optical constants in the database for our films?
Optical constants are not constants. They vary at different wavelength and by different processing technique. Processing techniques affect packing density, materials crystalinity etc. therefore affect optical properties. It is recommended that user should evaluate what optical constants sets are proper for his films. If user can not find optical constants in database, we can provide service to determine optical constants precisely with spectroscopic ellipsometry technique and then provide to user for use. • What if the film is not homogeneous? User can use average optical properties for that film. • Why measured thickness depends on initial input or start values? To speed up calculation, program always tries to start from the input thickness to minimize the sigma between measured and calculated spectra. Depends on the range, it is possible to miss true minima (global) and then will give out thickness obtained at local minima. There is trade off here. Wide range provides high possibilit
