The Design Of Nanometer Displacement Stage For Dual-probe AFM Alignment System

The measurement of nanoscale linewidth has always been the focus and difficulty in the field of nanometer measurements.The rapid development of integrated circuits needs to provide higher precision for line width measurement.Among numerous microscope,atomic force microscope is widely used in nanometer range of linewidth measurement,however,its probe size and measurement principle led to the linewidth measurement error.In this thesis,the dual-probe atomic force microscope which can eliminate the error caused by the probe size is researched in depth.The key of two-probe atomic force microscope is the alignment of the two probes in three dimensions,which provides the base points for the linewidth contour splicing obtained by the two probes.A translation stage is designed for dual-probe alignment in this thesis.The specific research contents are as follows:1.The design parameters of the stage according to the requirement of the atomic force microscope is determined.The alignment of the probe requires the nanoscale precision of the displacement stage.In order to meet the need of probe alignment,flexible hinge is used as the motion actuator,piezoelectric actuators are used to drive the stage and capacitive sensors are used to measure the displacement of the stage.The alignment of the probe requires that the stage has a large stroke in the x,y,and z directions,and the lever type displacement amplification mechanism is selected to ensure the stroke of the stage.In order to ensure the stable operation of the system,the matching needle tip clamping mechanism and pretensioning mechanism are designed.2.Mathematical formulas of stage working stiffiness,coupling stiffness,concentrated stress,natural frequency are calculated by establishing the theoretical model of the stage.According to the displacement performance analysis results,the impact of the structural parameters of the stage on the performance is clarified,and the structural parameters of the stage are determined according to the need for the needle.The reliability of the design is verified by finite element simulation.3.The hysteresis and creep characteristics of piezoelectric actuator are analyzed.An experimental system setup is constructed to detect the hysteresis and creep characteristics of piezoelectric actuator.In order to reduce the nonlinear error of piezoelectric actuator,it is controlled in closed loop.4.The linearity,repeatability,hysteresis error,cumulative coupling error and minimum resolution of the stage in the x,y,and z directions are verified through experiments by constructing an experimental setup for the stage.The maximum travel in the x direction is 110?m,the maximum linearity error is 0.00451%,the maximum cumulative coupling error is 97 nm,and the minimum resolution is less than 10 nm.The maximum travel in the y direction is 110 ?m,the maximum linearity error is 0.005%,the maximum cumulative coupling error is 136 nm,and the minimum resolution is less than 10 nm.The maximum travel in the z direction on the left is 55 ?m,the maximum linearity error is 0.0117%,the maximum cumulative coupling error is 87 nm,and the minimum resolution is less than 10 nm.The maximum stroke in the z direction on the right is 50 ?m,the maximum linearity error is 0.0138%,the maximum cumulative coupling error is 112 nm,and the minimum resolution is less than 10 nm.The final performance of the stage is in accordance with the design specifications and requirement of dual-probe alignment of the dual-probe atomic force microscope.