Sensitivity of the Ellipsometric Parameters to Angle-of-Incidence Variations

Abstract

Formulas by which the partial derivatives of the ellipsometric parameters psi and Delta with respect to the angle of incidence can be calculated are presented. These derivatives are plotted as a function of the angle of incidence, the refractive indices of the film, the substrate, and the immersion medium, and also as a function of film thickness on three-dimensional graphs. These graphs illustrate the angular regions in which angle-of-incidence errors are significant for typical materials. At the angles of incidence at which these derivatives are large, errors due to beam deviation and errors due to the use of noncollimated light or due to the use of specimens with rough or irregular surfaces can be significant. The results illustrate that the errors due to beam deviation are often significant in zone-averaged measurements when standard optical components with wedge angle tolerances of 0 degrees 3' of arc are used.

In Situ Ellipsometry to Monitor Swelling and Dissolution of Thin Polymer Films

“…Using expressions similar to Eq. [15] and [16] gives 80 ~ 0.035 ° and 6A = 0 ° for a 150 nm oxide film. The maximum analyzer offset is about one encoder increment, or 1•41 °.…”

“…The most significant sources of systematic error for our instrument are azimuth angle and angle of incidence (including beam deviation) errors. Treatments of these errors and expressions for uncertainties in A and @ are available (11,16,17). The azimuth angle errors include an offset in setting of the zero angle of the polarizer, and an index offset for the optical encoder relative to the zero azimuth of the analyzer.…”

A compact new-concept ellipsometer for accurate large scale thin film measurements

“…The characterization of properties of materials through optical investigation means offers several appealing advantages compared to other competing techniques [1][2][3][4][5][6][7][8][9][10]. First of all, at the common level of optical power used, such techniques are mostly not-invasive and not destructive.…”