i have read a text of prof. Eldenglawey .

Film thickness can be checked by

1-   SEM or AFM  (film-substrate ) cross section

2-    Using mass of the film, m according to the next details::

 W1 is the weight of cleaned substrate

W2 is the weight of cleaned substrate plus film

W2-W1= the weight of the film

ΔW=mg

m = ΔW/g

m=ρ.V   ;   ρ, is the density of film material and V is the volume of the film                   

the Volume  = (Width X Length X Thickness) of the film

3-  An interferometric method, more details is available at: TOLANSKY S. Multiple beam interferometry of surfaces and films. London: Oxford University Press, 1988: 147.