非接触光学三维纳米测头测量机理及应用研究

The development and application of micro devices are developing very rapidly. However, the present technologies can not realize the accurate measurement of the 3-dimensional morphology of their microstructures. Furthermore, the further enhancement and quantitative analysis of the performance of micro devices are limited. The existing contact 3-dimensional measurement method has a fatal constraint from the measurement force, and the traditional optical method has a fatal defect with low transverse resolution. Therefore, the true 3-dimensional measurement of micro structure with physical distinct dimensions has becoming an urgent scientific difficulty needed to be solved over the world. Being different from the present optical methods, this proposal aims to develop a new optical method to solve the low transverse resolution. In this proposal, based on the high off-plane (vertical) resolution in optical method measurement, the transverse measurement of optical measuring spot is transferred into vertical measurement through optical astigmatism and optical energy distribution measurement method, and nano resolution in transverse direction is achieved. And then, the optical 3- dimensional super-resolution measurement with nanometer is fulfilled. In theoretical research, this proposal tries to build the topological relationship between output signals and spatial energy distribution of the focused optical spot (this distribution is caused by the three dimensions of the measured micro-structure) through theoretical analysis, modeling and simulation. Further more, the optical 3-dimensional measuring theory will be studied and the corresponding technology will be developed based on this topological relationship. In experimental research, this proposal tries to develop an optical 3-dimensional probe with the resolution of better than 5 nm and repeatability of better than 20 nm. Then, as the investigated object, the measuring properties and evaluation method of the developed probe will be done.

目前微型器件研发与应用发展迅速，但现有技术无法实现其微结构三维形貌的准确测量，从而限制了其性能的进一步提升以及定量分析。现有接触式三维测量方法有测力影响的致命制约，传统光学方法有横向分辨力低的严重缺陷，因此微结构的真三维几何形状测量问题成为世界各国有待解决的测量科学难题。有别于现有光学三维测量方法，本项目拟采用新方法解决横向分辨力低的难题，即：基于光学测量中离面（纵向）空间分辨力高的特性，通过像散原理和光能量检测方法，将横向测量转化为纵向测量来实现横向测量的纳米分辨力，从而在三维方向上都实现纳米分辨力的超分辨三维测量。理论上，拟通过理论分析、建模仿真，研究输出信号与聚焦光斑能量三维空间分布（由测量点处微结构三维形状引起）的拓扑关系，并建立三维光学测量理论及开发三维纳米测量技术；实验上，拟研制5纳米三维分辨力、20纳米重复性的新型三维光学测头，并以该测头为对象研究其三维测量特性及评定方法。

随着各种半导体器件、超精密器件、MEMS器件的广泛应用，在其制造过程中对三维轮廓的测量要求也越来越高。光学三维测量方法作为典型的、常见的非接触式测量方法，不存在测量力及其引起的表面破坏等问题，但由于光学衍射的存在，现有的方法和技术普遍存在横向分辨力低的缺点，提高光学非接触测量方法的横向分辨力成为急需解决的科学难题。.. 针对这一问题，本项目提出了一种新的三维纳米非接触测量方法和技术，其基本原理是：从像散原理出发，定量分析像散光斑的能量与强度分布，分别建立测量信号与纵向和横向位移的关系模型，结合光学像散测量法与反射能量测量法实现微纳结构的光学三维纳米测量；基于该方法设计了测头光路，研制了兼具测量、瞄准、观测功能的非接触式光学测头；在研制的非接触式光学三维纳米测头的基础上，结合三维运动台，搭建了包含测量模块、运动模块、成像模块、信号采集处理模块和测量控制模块的非接触式光学三维纳米测量系统，并开发了相应的控制技术。..在搭建的测量系统上进行的一系列性能验证实验的结果表明，本项目研制的三维测头在X、Y和Z方向上的分辨力均优于5nm，重复性优于20nm，在直接测量模式下，测头X、Y方向上的测量范围为5 μm，Z方向上的测量范围为2 μm；测头在测量系统中可实现触发测量，此时的测量范围在前面的基础上可以再叠加上微动台的行程，实现大量程的三维纳米测量。.. 相较于传统光学测量方法微米、亚微米的横向分辨力分辨力，本项目研制的光学非接触式测头将横向分辨力提升了2-3个数量级，这也使得测头的应用更加广泛。在研制的三维测量系统上进行的应用研究成功实现了1 μm/2 μm/6 μm微台阶的高度测量、单晶硅切片的边缘检测及叉指电极的线宽测量。后续的研究将集中于测头在超精密机械加工、半导体元件刻蚀、MEMS器件生产等工业场景的应用。