UNCERTAINTY CONSIDERATIONS FOR INTERFEROMETRIC STABILITY TESTING

摘要

Material stability is an important parameter for EUV lithography, space instrumentation, and metrology in general. In both EUV lithography and space, more information is needed about material stability during an atmospheric to vacuum transition. For metrology instruments in general, determining the causes of drift, as well as the most stable materials is becoming more critical as uncertainty decreases. A measurement system with high resolution and low measurement uncertainty is required for the investigation into material stability. We are investigating an instrument that can measure the length change of a 50 mm long sample with a 10 pm (k=2) measurement uncertainty for 10 minute measurements and 100 pm (k=2) uncertainty for four week measurements. Here, we present an investigation of the uncertainty contributors of this instrument and design considerations for two balanced interferometers to measure material stability.