Optical film thickness sensors with interferometric or reflectometric methods are used, so that the film thickness of a few millimeters up to 10 nanometers can be determined non-destructively. It does not matter whether it is a matter of measuring self-supporting layers (e. g. foils) or single or multi-layer systems on a substrate. Materials such as silicon, which are not transparent in visible light, can also be reliably determined thanks to the large selection of sensors with different light sources, measurement spot sizes and thickness measuring ranges.
There are multiple applications possible within film thickness measurement, especially of thin films. Typical tasks are located in the field of (thin film) photovoltaics, medical technology, semiconductor, flat-panel display and OLED production or the glass and optical industries. Typical films and film stacks that are measured are:
film thickness of an Anti-Reflective Coating (ARC)
film thickness of Photoresist (e.g. AZ photoresist)
film thickness of a Hard Coating
film thickness of Thin Conductive Oxides (TCO)
film thickness of Tin Doped Indium Oxides (ITO)
film thickness of Drug Eluting Films
The devices of our MicroProf® series allow not only to perform punctual and profile film thickness measurements but furthermore features an innovative 3D-Mapping Mode that allows the homogeneity determination of the film thickness distribution on a larger sample area. Manufacturers of coated products such as solar cells, technical glas, blood glucose test strips, CD's and DVD's as well as semiconductor and MST products use 3D film thickness maps to quickly identify possible failure sources and new potentials for optimization in their coating processes.
For the 3D visualisation, the coated surface is first scanned contact-free by means of a motorized x, y-table underneath the film thickness sensor. This process results in up to 100 million individual measuring points, which are automatically calculated with powerful hardware and software to a high-resolution 3D image of the entire coating. With a mouse click, information about the specific coating thickness at a given position can be retrieved, profiles can be recorded or the entire homogeneity of the coating can be evaluated.
FRT offers the right surface measuring device for every layer: Whether laboratory, development, quality assurance or production - with the multi-sensor measuring devices from the MicroProf® series you can measure your coatings easily and contact-free. The determination of the film thickness can be combined with topography measurements and can also be fully automated.
Depending on your application, different sensors are used: For the determination of film thicknesses in the sub-micrometer range, from a few ten nanometers to several ten micrometers, as well as for the analysis of complex multilayer structures with high resolution, the FTR sensor was developed in-house. Depending on the requirements, the thin-film sensor is used in variants with different wavelength ranges, so that optimum measuring conditions are offered for different materials and film thickness. For small structures, the lateral resolution can be increased up to 5 µm.
The evaluation of the reflection spectra of the interferometric sensor is carried out by means of a powerful software developed with our film thickness experts: depending on the film thickness and layer system, both an evaluation by means of FFT (Fast Fourier Transformation) and a model-based fit based on the material data or a combination of both methods are used. This allows the analysis of very thin films in the nanometer range with high resolution and fast measurement results. An extensive database with refractive indices and absorption coefficients of a variety of materials such as glasses, semiconductors, oxides, plastics, etc. is included in the scope of delivery. In conjunction with our measuring systems, the FTR can be used to generate not only point measurements but also film thickness profiles and film thickness mappings with high lateral resolution. The sensor is also excellently suited for integration in inline control.
In addition, this sensor can also be used to analyze multi-layer systems with up to ten layers. Transparent substrates coated on both sides can also be modeled. It is also possible to characterize components in which the layer system is located between thicker materials, such as OLEDs that are encapsulated with glass on one side and have a metal electrode on the other.