T.A. Mykhaylyk, N.L. Dmitruk, S.D. Evans, I.W. Hamley, J.R. Henderson
Comparative characterisation by atomic force microscopy and ellipsometry of soft and solid thin films
Surface and Interface Analysis 39 (2007) 575–581
Ellipsometry and atomic force microscopy (AFM) were used to study the film thickness and the surface roughness of both 'soft' and solid thin films. 'Soft' polymer thin films of polystyrene and poly(styrene-ethylene/butylene-styrene) block copolymer were prepared by spin-coating onto planar silicon wafers. Ellipsometric parameters were fitted by the Cauchy approach using a two-layer model with planar boundaries between the layers. The smooth surfaces of the prepared polymer films were confirmed by AFM. There is good agreement between AFM and ellipsometry in the 80–130 nm thickness range. Semiconductor surfaces (Si) obtained by anisotropic chemical etching were investigated as an example of a randomly rough surface. To define roughness parameters by ellipsometry, the top rough layers were treated as thin films according to the Bruggeman effective medium approximation (BEMA). Surface roughness values measured by AFM and ellipsometry show the same tendency of increasing roughness with increased etching time, although AFM results depend on the used window size. The combined use of both methods appears to offer the most comprehensive route to quantitative surface roughness characterisation of solid films.
Cited Articles
-
Franta D., Ohlídal I.,
Comparison of effective medium approximation and Rayleigh–Rice theory concerning ellipsometric characterization of rough surfaces,
Optics Communications 248 (2005) 459–467 -
Mistrík J., Yamaguchi T., Franta D., Ohlídal I., Hu G. J., Dai N.,
Optical properties of slightly rough LaNiO3 thin films studied by spectroscopic ellipsometry and reflectometry,
Applied Surface Science 244 (2005) 431–434 -
Franta D., Ohlídal I., Klapetek P., Roca i Cabarrocas P.,
Complete characterization of rough polymorphous silicon films by atomic force microscopy and the combined method of spectroscopic ellipsometry and spectroscopic reflectometry,
Thin Solid Films 455–456 (2004) 399–403 -
Franta D., Ohlídal I.,
Ellipsometric parameters and reflectances of thin films with slightly rough boundaries,
Journal of Modern Optics 45 (1998) 903–934