PHASE-SHIFT CORRECTIONS IN DETERMINING THICKNESSES OF TRANSPARENT FILMS ON REFLECTIVE SUBSTRATES

Thicknesses of transparent films on reflective substrates are being measured non-destructively by CARIS (constant angle reflection interference spectroscopy) and by VAMFO (variable angle monochromatic fringe observation). Both cases are based on the interference between the radiation reflected from the dielectric-air interface and that from the dielectric-substrate interface. For most accurate thickness measurements phase-shift thickness corrections must be made due to the phase-shift on reflection at the two interfaces not being equal. Phase-shift thickness corrections have been calculated for various insulating films on commonly used substrates. In addition universal type charts are presented which simplify the calculation of phase-shift thickness corrections for metals or semiconductors which are bare or covered with a transparent dielectric film. © 1968.