Ultra-precise Coordinate Metrology of Three-dimensional Objects at Micrometer and Nanometer Scales

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The objective of this award is to investigate and develop enabling technologies for achieving ultra-precise coordinate metrology of 3-dimensional objects at micrometer and nanometer scales. These enabling technologies will then be used to realize a three-axis probing system capable of measuring undercuts and free-forms of objects whose critical dimensions of surface form are scaled down to sub-100nm. The approach consists of four phases. First, a systematic approach to the design and prototyping of active three-axis reorientable probing systems is proposed to achieve two distinguishing features: (i) the orientation of the probe and the position of the probe tip in the scanning plane are actively controlled, and (ii) the tip-sample interaction forces in two axes are actively controlled. Second, tip motion control and stability analyses are proposed to enable stable scanning of sub-100nm three-dimensional objects having unknown geometry and large geometric variation. Third, real-time calibration of actuation gain and compensation of thermal drift are proposed to significantly reduce the effect of the system's time variance for simultaneously achieving ultra-precise and high-throughput coordinate metrology. Fourth, two-axis force sensing and force control schemes are proposed to enable precise control of the tip-sample interaction in the scanning plane.These technologies will enable precise control of 2-axis deflection and of 2-axis tip-sample interaction force simultaneously, both of which are very important for probing vertical and re-entrant features using the proposed probing system. If successful, the enabling technologies created from this award will lay the foundation for realizing active 5-axis probing systems and will lead to transformational changes in three-dimensional coordinate metrology at micrometer and nanometer scales. Specifically, the probing system will not only have significant impact on coordinate metrology at micrometer and nanometer scales, but also on advanced instrumentation in a wide range of fields including biology, chemistry, medicine, and physics.