Comparative scatterometric CD and edge profile measurements on a MoSi mask using different scatterometers

Abstract:
At PTB a new type of DUV scatterometer has been developed. The concept of the system is very variable, so that many different types of measurements like e. g. goniometric scatterometry, ellipsometric scatterometry, polarisation dependent reflectometry and ellipsometry can be performed. The main applications are CD, pitch and edge profile characterisation of nano-structured surfaces mainly, but not only, on photomasks. Different operation wavelength down to 193nm can be used. The system is not only a versatile tool for a variety of different at-wavelength metrology connected with state-of-the- art photolithography. For the evaluation of the measurements the inverse diffraction problem has to be solved. For this purpose a special FEM-based software has been developed, which is capable to solve both the direct diffraction problem and the inverse diffraction problem. The latter can be accomplished using different optimisation schemes. To test both our new scatterometer and the newly developed evaluation software we started systematic comparative CD and edge profile measurements on a state of the art MoSi phase shift mask. In this paper first results are presented and compared with results of a commercial scatterometer.