SOPRA SE300: a new tool for high accuracy characterization of multilayer structures

In order to characterize 300-mm wafers at different stages of the IC manufacturing, a new tool based on spectroscopic ellipsometry has been recently developed at SOPRA. This new instrument called SE-300 has some important new features compared to the other ellipsometers of SOPRA or of the competition. First the optical setup allows to obtained very small measurement spots down to 35×45 μm in polychromatic light to be able to work from deep UV 190 nm to near infrared; second the combined monochromator/spectrometer is directly setup on the analyser arm and allows both multichannel and scanning measurements on the same spot. Scanning measurement made with a real double monochromator including prism and grating allows very accurate measurement that can be used to extract optical indices and solve complex multilayer structures. Multichannel measurements are made through a prism/grating spectrometer with quasi-linear dispersion in wavelength. All the elements (robotics, prealigner, XYZ mapping, pattern recognition) are fully compatible with the new generation of 300-mm wafers. Practical results obtained in a realistic environment (I300I acceptance tests and MEDEA project) are presented.