Spectral interference ellipsometry for film thickness measurement on transparent substrate

Measuring film thickness on transparent substrate is crucial and universal for semiconductor chips. This paper proposes an orthogonal polarization common-path film thickness measurement system without the frustration of back-surface reflection based on spectral interference ellipsometry. The proposed system demonstrates that the phase stability of spectral interference reached 5×10-4 rad under common path. Combined with ellipsometry, the back-surface reflection issues were theoretically deduced and solved by the proposed system. The measured thicknesses of three kinds of film specimens on transparent substrates agreed well with those determined using a commercial ellipsometer. The measurement precision was greater than 1 nm.