Photoresist is used in many applications. The type, the thickness of photoresist (PR) and substrate it is deposited on can be different.
In most cases, it is necessary to measure the thickness of the PR to control the process. MProbe™  Vis reflectometer (400nm -1000nm wavelength range, thickness range: 10 nm -50μm) can be successfully used for this measurement. Illumination wavelength range is, typically, limited using a long pass filter (LP500) to avoid PR exposure. Final wavelength range (with LP500 filter): 500-1000nm. Photoresist optical dispersion is represented using Cauchy model, refractive index (n) is,typically, available from manufacturer. If this information is not available, it is possible to measure thickness and R.I. directly with MProbe system.

In cases where  small spot measurement is required, MProbe™  Vis MSP is used.