高深宽/径比MEMS器件3D纳米测量探头理论模型及关键技术

High-accuracy measurement for the three-dimensional geometric sizes of the high aspect ratio MEMS devices is a problem in nano-measurement field. The detection techniques and approaches with the characteristics of high accuracy, low stiffness, micro measuring sphere and large range are required urgently. However, the existing probing systems worldwide cannot meet the requirements. In this research, some theoretical models and key techniques will be studied to reduce the measurement force, improve the quality of the micro measuring sphere, expand the probe’s measurement range and ensure the accuracy of the probe. A elastic mechanism is designed in accordance with mechanical and thermal symmetry principle. By theoretical modeling, simulation，optimization and experimental verification, the characteristics of the elastic mechanism, such as low stiffness, large range and high stability can be achieved.Tungsten carbide stylus with high accuracy micro sphere can be manuanfactured in the weightless condition by using the eletrical discharge method and Taguchi techniques. A 3D optical sensor is constructed by integrating a laser interferometer and a auto-collimator. A scanning mirror is used to expand the probe’s measurement range instead of the original reference mirror in the interferometer. FPGA is employed to realize high-speed signal processing. With the whole-system accuracy modelling and error correction, the accuracy of the probe can be ensured. Finally, a contact scanning 3D nano probing system will be developed based on the above models and key technologies. Its working requirements include: the uncertainty is less than 20 nm, the measurement range in 3D is 40 μm respetively, the diameter of the micro sphere is from 25 μm to 100 μm, and the stiffness is less than 0.1 mN/μm. The research rasults will promote the development of the nano probe techniques, expand the probe’ application field and have important scientific significance and practical value for the development of MEMS technology and MEMS industry.

高深宽/径比MEMS器件三维几何尺寸的高精度测量是当前纳米测量领域的难题，迫切需要兼具高精度、小测力、微测球、大量程等特点的检测技术和手段，国内外现有探头还不能完全满足此要求。本项目研究减小探头测力、提高微测球质量、扩大探头量程、保证探头精度的理论模型和关键技术。设计符合力学、热学对称原理的弹性机构，通过理论建模、仿真优化和实验验证，实现小测力、大量程和高稳定性；利用火花放电和田口实验技术，在失重条件下烧制高精度碳化钨微测球；基于激光干涉和自准直原理构建三维传感器，用扫描镜代替干涉仪参考镜以扩大量程，采用FPGA实现高速信号处理；通过全系统精度建模和误差修正技术保证探头精度；实现接触扫描式3D纳米探头系统，主要指标：不确定度20纳米，测球直径25-100微米，测力梯度小于0.1毫牛/微米，量程40微米。研究成果对推动探头发展，促进我国MEMS技术和产业发展具有重要科学意义和应用价值。

高深宽/径比MEMS器件的高精度测量难题需要由装有接触式测头的微纳米三坐标测量机来完成，现有国内外探头尚无法同时兼顾高精度、小测力、微测球、大量程等特点，无法满足测量需求。为解决高深宽/径比MEMS器件三维几何尺寸的测量难题，本项目深入分析探头性能和弹性机构力学特征之间的关系，设计不同形状的弹性机构，分别对其进行力学特性分析，建立其刚度、动态特性等模型，依据理论分析结果，研究减小探头测力、扩大探头量程、提高微测球质量、保证探头精度的理论模型和关键技术；基于火花放电和金属熔烧加工原理，通过田口实法，探索各工艺参数对微球成形的机理作用，确定微球可控制备当中关键参数的有效区间；研究各种因素对探头性能指标的影响规律和传递特性，建立相应的理论模型，研究适用于3D纳米扫描探头系统的三维高精度传感新方法和新技术；研究探头三维解耦标定技术，为测试探头系统各项性能指标研究科学的实验方法，设计相应的实验装置；分析探头系统的主要误差来源，根据各项误差特性，研究科学有效的误差补偿方法，以保证探头系统精度指标的实现。总结凝练出了弹性机构簧片以及各探头灵敏度模型、刚度模型等的设计、分析、优化方法。设计出了符合热、力学对称原理的弹性机构，制备出了直径在25-100 μm，球度及偏心小于0.5 μm的一体式微球形探针，开发了基于单传感器以及基于迈克尔逊干涉仪的三维传感新方法。研制出了基于楔形棱镜的接触触发式探头（探头指标：量程±14 μm，分辨率10 nm，刚度1 mN/μm，重复性9.1 nm）; 基于双层悬浮机构的接触扫描式探头（探头指标：量程±10 μm，分辨率5 nm，刚度1 mN/μm，重复性20 nm）；基于迈克尔逊干涉仪和自准直原理角度传感器的接触扫描式探头（探头指标：量程±20 μm，分辨率1 nm，刚度0.5 mN/μm，重复性30 nm）。探头研制过程中涉及弹性机构、灵敏度和刚度等模型的设计、分析、仿真、优化等方法可作为探头结构设计的基础理论，对后续探头性能优化具有指导作用。