In general, interferometry is used to measure surface shape, including thin-film thickness [1]. It is a powerful means to measure a surface using light's interference phenomenon. The thickness can be measured by the phase difference of the interferograms generated on the upper and lower surfaces of the thin film [2].

Semiconductor thin films are layers of semiconductor material that are deposited or grown, typically ranging from a few nanometers to microns in thickness, on a substrate using various deposition processes such as chemical vapour deposition (CVD) or electron beam (e-beam) evaporation.

Thin film deposition involves processing above the substrate surface (typically a silicon wafer with a thickness of 300–700 μm). Material is added to the substrate in the form of thin film layers, which can be either structural layers or act as spacers later to be removed.

Silicon nitride (Si3N4) is a common choice for this purpose. Size and Weight Reduction: Thin film components allow for miniaturization, enabling the creation of smaller and lighter electronic devices.