At Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany, a new type of deep ultraviolet scatterometer has been developed and set up. The concept of the system is very variable and versatile, so that many different types of measurements, e.g., classical scatterometry, ellipsometric scatterometry, polarization-dependent reflectometry, and ellipsometry can be performed. The main application is the characterization of linewidth/critical dimension (CD), grating period (pitch), and edge profile of periodically nanostructured surfaces mainly, but not only, on photomasks. Different operation wavelength between 840 and 193 nm can be used, giving also access to a variety of different at-wavelength metrology connected with state-of-the-art photolithography. It allows to adapt and to vary the measurand and measurement geometry to optimize the sensitivity and the unambiguity for the measurement problem. In this paper the concept, design, and performance of the system is described in detail. First measurement examples are shown and current and future applications are discussed.

A new deep UV transmission microscope for traceable micro-and nanometrology is currently being set up at the Physikalisch-Technische Bundesanstalt (PTB), the National Metrology Institute of Germany. The new microscope is especially designed to enable linewidth measurements of micro-and nanostructures with an unsurpassed absolute measurement uncertainty of down to 10 nm (95% confidence interval). The optical resolution is about 100 nm. The main field of this tool will be critical dimension (CD) metrology of photomasks used in optical lithography. In particular, this system offers the possibility of 'at-wavelength' metrology for the currently applied 193 nm lithography technology. The high lateral resolution will be attained by means of 193 nm excimer laser radiation for illumination in conjunction with a high-aperture objective (NA = 0.9). The illumination and imaging system will provide various imaging modalities, ranging from ordinary brightfield to specially structured illumination schemes. Traceability to the SI unit 'meter' will be accomplished by means of laser interferometry. The mechanical set-up is characterized by an ultra-stable bridge construction on a granite base and has been designed with special emphasis on realizing a positioning stability in the nanometer range. The instrument is being set up in the Clean Room Centre of the PTB and will be ready for operation in mid 2009. Simulation calculations, based on a rigorous optical modeling of the expected microscope images, are presented. These simulations are made for the important application of measuring Cr structures on quartz photomasks. Based on these simulations and on available data of the uncertainties of various experimental parameters-including instrument and sample parameters-expected uncertainty budgets for the measurement of the width of Cr lines on quartz substrates are estimated.

At PTB a new type of DUV scatterometer has been developed and set up. 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. It allows also to adapt and to vary the measurand and measurement geometry to optimise the sensitivity and the unambiguity for the measurement problem. In this paper the system is presented and described in detail for the first time. Additionally first measurements of grating test structures on a 193nm CoG photomasks are presented. The measurements have to be evaluated by solving the inverse diffraction problem. We finally give a short overview of the evaluation method developed and used by us.

Deformation monitoring requires the detection of smallest changes, always at the limits of technical feasibility. Trying to push these limits further, we have realised two terrestrial ranging instruments: a long-range 1D electro-optic distance meter and a 3D multilateration-capable sensor system of 50 m range. The former one is intended as primary standard for the calibration of geodetic instrumentation with low uncertainty to the SI definition of the metre. The latter one is intended for monitoring larger monuments like VLBI antennas. In this contribution, we describe the technical challenges and our solutions for such instrumentation. We use the two-colour method for inline refractive index compensation. As common optical source, we developed a versatile multi-wavelength generator based on two Nd:YAG lasers stabilised by a phase-locked loop realised by Field Programmable Gate Arrays (FPGA). The 1D interferometer uses custom-designed achromatic optics and a mechanical frame optimised for form stability under field conditions. The phase demodulation system allows for maximum range flexibility from several meters up to several kilometres. The base ranging unit of the 3D multilateration system adheres to a different demodulation technique, which allows a relatively simple interferometer head design. This approach requires a sophisticated source modulation scheme limiting the applicability to distances over 15 m up to approximately 50 m in our case.

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