Reflectivity Thickness Corrections for Silicon Dioxide Films on Silicon for VAMFO [Letter to the Editor]

In recent years, a great deal of interest has been centered on the non-destructive measurement of the thicknesses of oxide or glass films on silicon, based on the production of interference fringes by varying the angle of observation (VAMFO—variable angle monochromatic fringe observation
^1–3
) or by spectrophotometric variation of the observed wavelength of radiation.
^4–7
The film thickness d can be determined from d = (Nλ/2n
2
cos θ
2
) + Δt
φ
+ Δt
r
, (1) where N is the order given by N = 1/2, 3/2, 5/2, ··· for minima; n
2
is the SiO
2
refractive index at wavelength λ; θ
2
is the angle of refraction in the SiO
2
; Δt
φ
is the phase shift correction; and Δt
r
is the reflectivity correction.