Characterizing surface roughness of thin films by polarized light scattering

The polarization of light scattered by the surface of a material contains information that can be used to identify the sources of that scatter. In this paper, first order vector perturbation theory for light scattering from interfacial roughness of a dielectric layer is reviewed. In addition, methods for calculating the Stokes vector for scatter from multiple sources and for decomposing a Stokes vector into contributions from two non-depolarizing scattering sources are provided. The polarization of light scattered from interfacial roughness depends upon the relative roughness of the two interfaces and the degree of phase correlation between the two interfaces. Experimental results are presented for three cases: a nominally conformal film, a nominally anticonformal film, and a lateral offset roughness film. The method works well for the nearly conformal film. Difficulties that arise for the other two cases are discussed.

[1]  A. Mayes,et al.  Block copolymer thin films : Physics and applications , 2001 .

[2]  Z. Kam,et al.  Absorption and Scattering of Light by Small Particles , 1998 .

[3]  J. M. Elson,et al.  Light scattering from surfaces with a single dielectric overlayer , 1976 .

[4]  J. P. Rahn,et al.  Light scattering from multilayer optics: comparison of theory and experiment. , 1980, Applied optics.

[5]  David S. Flynn,et al.  Polarized surface scattering expressed in terms of a bidirectional reflectance distribution function matrix , 1995 .

[6]  Thomas A. Germer,et al.  Polarization of light scattered by microrough surfaces and subsurface defects , 1999 .

[7]  G. Mulholland,et al.  Polarized light-scattering measurements of dielectric spheres upon a silicon surface. , 1999, Optics letters.

[8]  J. Merle Elson,et al.  Multilayer-coated optics: guided-wave coupling and scattering by means of interface random roughness , 1995 .

[9]  H. V. Hulst.  Light Scattering by Small Particles , 1957 .

[10]  J. Stover.  Optical Scattering: Measurement and Analysis , 1990 .

[11]  E. Kroeger,et al.  Scattering of light by slightly rough surfaces or thin films including plasma resonance emission , 1970 .

[12]  Thomas A. Germer,et al.  Goniometric optical scatter instrument for bidirectional reflectance distribution function measurements with out-of-plane and polarimetry capabilities , 1997, Optics & Photonics.

[13]  J. Elson,et al.  Infrared light scattering from surfaces covered with multiple dielectric overlayers. , 1977, Applied optics.

[14]  J. M. Elson,et al.  Diffraction and diffuse scattering from dielectric multilayers , 1979 .

[15]  Bradley W. Scheer.  Development of a physical haze and microroughness standard , 1996, Optics & Photonics.

[16]  Thomas A. Germer,et al.  Goniometric Optical Scatter Instrument for Out-of-Plane Ellipsometry Measurements , 1999 .

[17]  T. Germer.  SCATMECH: Polarized Light Scattering C++ Class Library , 2000 .

[18]  Germer.  Measurement of roughness of two interfaces of a dielectric film by scattering ellipsometry , 2000, Physical review letters.

[19]  T. Germer,et al.  Angular dependence and polarization of out-of-plane optical scattering from particulate contamination, subsurface defects, and surface microroughness. , 1997, Applied optics.

[20]  T A Germer,et al.  Polarization of out-of-plane scattering from microrough silicon. , 1997, Optics letters.