Measuring the Thickness of Metal Films: A Selection Guide to the Most Suitable Technique

The determination of the thickness has a fundamental importance in all the fields in which the implementation of films and coatings are required and takes a crucial role in electroplating sector. The thickness influences many aspects of the coatings such as electrical, mechanical, corrosion protection and even aesthetical properties. In the multitude of applications of thin layer coatings, the variability of thicknesses and materials is very high as well as the possible techniques that can be used to determine the characteristics of the layers of interest. The first distinction that can be made between these techniques is that which divides destructive techniques from non-destructive ones, in which however the semi or micro-destructive techniques are immediately difficult to place. Other important parameters to consider are the cost, both for the purchase of the instrumentation and for each single analysis, the difficulties in preparing and measuring the sample and data processing and obviously the detectable thickness ranges, the possible measurable materials, precision and accuracy. The purpose of this work is to compare the characteristics of the various investigation methods, with a particular focus on metal films applications, so that it will be easier to choose the most suitable technique for each purpose. Among the many techniques examined, the main ones are electron and optical microscopy, profilometry, ellipsometry and X-ray techniques.