Measurement Of Thickness Of Thin Film

Measurement of thickness of thin film:
The thickness of thin film is measured using multiple beam interferometry. The film is deposited on a substrate such that it has a step. The film and remaining surface of the substrate is then coated with aluminum film (by evaporation). Since the reflection coefficient of both the surfaces are high, multiple beam fringes in the wedge are obtained. The fringe pattern from the two area of the surfaces (where there is a film and where there is no film) , are shifted. This fringe step is used to measure the thickness of the film      .

Fig. A: Experimental arrangement to measure the thickness of thin film