Gerhard Hoppen

DUV water immersion technology extends linearity: first results from the new 65nm node CD metrology system LWM500 WI

The increased requirements on reticles for the 65nm technology node with respect to CD homogeneity and CD mean to target requirements call for a metrology system with adequate measurement performance. We report on the new water immersion technique and the system concept of the worlds first optical CD metrology system based on this technology. The core of it is a new DUV immersion objective with a NA of 1.2, using illumination at a wavelength of 248nm. The largest challenge of the water immersion technology was the fluid handling. The key compo-nents, a water injection and removal unit, developed by MueTec, solve this issue. To avoid contaminations the purified DI water is micro-filtered. An environmental chamber guarantees extremely stable measurement conditions. The advantages of optical CD measurements in transmitted light compared to CD-SEM is shown. With this system, already installed, excellent results for short- and longterm repeatability for both linewidth and contact measurements were achieved on COG, KrF HT and ArF HT masks. The linearity range of the system is extended down to 220nm. A comparison of CD measurements between the different tool generations such as the Leica LWM250/270 DUV at 248nm with a NA of 0.9 is shown. An outlook on the future potentials of optical mask CD metrology finalises this report.

Ultra High Performance Microscope Objectives: The State of the Art in Design, Manufacturing and Testing

During the last years, new microscope applications require an increased resolution which enforces the development of new state of the art high NA immersion objectives. With the introduction of the 4Pi confocal fluorescence microscope, the increase of the numerical aperture from NA=1.4 to NA=1.46 makes sense, although the gain of lateral resolution is quite small. On the other hand, for inspection and metrology in the semiconductor industry the continuously decreasing structures need the highest possible resolution, which can be achieved with high NA water immersion objectives working in the DUV wavelength range. Building this kind of objectives requires special measuring and testing technologies and a manufacturing precision which has never been realized before in series production.