Non-collimated beam ellipsometry

Abstract

A new method of polarization reflectometry for mapping purposes is presented. Two different optical arrangements were built to study the specific features of the new technique that uses non-collimated illumination giving multiple-angle-of-incidence information from rapid measurements of the whole area. The prototypes were built in the form of wide-angle 3-wavelength ellipsometers using film polarizers. Using pinhole-CCD-matrix detector arrangement, the detection is almost background free. It can provide real-time polarization state parameter maps (and thicknesses and/or refractive index maps) over a relatively large area of the surface with 0.5-1 mm lateral resolution. The speed of the measuring system makes it suitable for use even on production lines. The accuracy of the device is not higher than that of standard ellipsometers, but it is enough for determining the thickness of the silicon-dioxide film with subnanometer and the angle-of-incidence with subtenthdegree precision. We used the prototype for mapping purposes in the case of homogeneity check of ion implantation in silicon, thickness and porosity mapping on electrochemically etched porous silicon layers, thickness mapping on a polysilicon/silicondioxide layer structure. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.