| Nano-geometrical characteristic size measurement is the key technique to support and improve the quality and performance of integrated circuits and micro & nano technology products.In order to obtain accurate and consistent measurement results,it is necessary to realize traceability in nano-scale and establish nanometrology transfer system in national level.Therefore,the world’s major developed industrial countries are vigorously building national primary nanometrology standard devices.In contrast,our country seriously lags behind in this area of nanometrology,and there are not national primary standard devices and reference materials,which results in our industries have to trace to foreign countries in nanometrology area.Nowadays one of the most important challenges in nanometrology is that the measurement range has increased from tens of micrometers to tens of millimeters,but the expected measurement uncertainty is still in nanoscale.Therefore,there is a pressing need to achieve accurate measurement for nano-geometrical characteristic parameters within millimeter measurement range,and to make sure that all of these parameter values can be directly traced back to SI units.In this dissertation,a device named“Metrological Standard Device for Nano-geometrical Characteristic Size in Millimeter Rang” has been developed,which consists of four major components: 3D multi-stage displacement system,traceable metrological AFM measuring head,multi-degree of freedom laser interferometry system in sub-nanometer scale & measuring control system.The key technologies include:1.Aiming at the problem of high friction for sliding mode and poor stability for rolling mode,a high-stability "air bearing & sliding hybrid movement" method is proposed,which overcomes the technical difficulty that micro-vibration inherently exists in air bearing systems;Furthermore,a large range stage that can adjust & control six degrees of freedom,and can reach to nano-scale resolution is developed.The air bearing guide rail is realized for directly scanning nano-geometrical characteristic sizes within the measurement range of 50 mm × 50 mm × 2 mm.2.Aiming at the inherent surface distortion caused by the spherical surface scanning trajectories of the conventional AFM,the designed AFM probe adopts novel cantilever position detection optical structure for planar scanning.A spot tracking technology for three-dimensional orthogonal scanning is proposed,with the developed traceable AFM head can realize three-dimensional orthogonal plane scanning.The resolution level is better than 0.5nm.3.Aiming at the requirement of full-degree-of-freedom adjustment and positioning of the displacement system,a high-stability laser interferometer system with the capability of measuring12 degrees of freedom for position and posture is developed.Aiming at the problem of the large nonlinear errors and low effective resolutions existed in conventional interferometer that makes it unable to measuring nanometer distances,a differential optical eight-pass polarization laser interferometer has been developed,which the resolution can reach to 0.02 nm.Furthermore a "harmonic separation correction method" is also proposed,the purpose of which is to correct all harmonic components of the nonlinear error of the multi-pass laser interferometer.The work of the dissertation fills the gaps of nanometer geometric characteristic size measurement and traceability in large range area in China.The achieved technical performance are: maximum measurement range in three-dimensional space is50mm×50mm ×2 mm,and the optimal measurement standard uncertainty is less than 2nm.These measurement capabilities are verified by the comparison with the of PTB Germany and VLSI United States,which meets the requirements of international equivalence. |
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