基于UAFM导电薄膜弹性模量检测及成像技术的研究

Using the solution organic and inorganic semiconductor materials, to produce a variety of electronic devices on flexible substrates based on the printing technology, is a revolutionary advanced manufacturing technology in recent years in the field of microelectronics. With the reduction of thickness of conductive film and the integration increasing of electronic components, the failure induced by conductive film becomes more and more, so the non-destructive analysis of the film is very important. Controlling the defects inculuding sub-surface defects of conductive thin film to ensure its mechanical properties in the nano-electronic, is beneficial to improve the performance of the device. The non-destructive testing technique based on ultrasonic atomic force microscopy (UAFM) can measure elastic modulus at nano-scale, but the elastic modulus image cannot be obtained during scanning at present stage and the model need to be improved also. In this project, the non-destructive detecting technique based on ultrasonic atomic force microscopy will be improved by which the elastic modulus image can be obtained in si-tu during the scannning with the frequency tracking system. The contact model between tip and sample will be built according to the tip shape. The vibration model of micro-cantilever will be optimized to fit the variation of experimental parameters on contact resonance frequency and build the relation between the contact stiffness and contact resonance frequency of the micro-cantilever. It has important value for basic research and potential application and will promot the application of nano-printing into micro-electronics to carry out the project.

利用溶液化有机与无机半导体材料，在柔性基底上采用印刷技术制造各种电子器件，是近年来在微电子领域里出现的一种革命性的先进制造技术。然而，随着电子元器件集成度的提高和导电薄膜厚度的降低，导电薄膜的失效问题越来越多，薄膜无损分析显得尤为重要。在纳米级元器件中控制导电薄膜的缺陷、次表面缺陷保证其机械性能，将有利于增加器件的可靠性。超声原子力显微镜(UAFM)新技术可以实现纳米级薄膜的无损测量和弹性模量表征，但还不能进行直接扫描成像且理论模型需要进一步完善。本项目拟对UAFM纳米无损检测技术进一步发展，构建并完善UAFM检测系统，通过理论分析及频率追踪系统开发，实现弹性模量扫描直接成像技术；建立探针与试样的接触模型，分析薄膜弹性、次表面缺陷等对接触模型的影响；完善悬臂梁的振动模型，建立接触刚度和悬臂梁谐振频率的关系。本项目的开展具有重要的基础研究和潜在应用价值，将推动纳米印刷技术在微电子方面的应用。

随着大规模集成电路向高密度、高速方面的发展，器件的特征尺寸已减小至纳米尺寸，这必然要求电子元器件和微型集成电路中有较低介电常数（衡量绝缘体储存电能的性能）的绝缘介质薄膜来降低线间串扰和功耗等。纳米多孔氧化硅具有低介电常数、热稳定性好、力学强度高、尺寸稳定以及与集成电路工艺兼容性好等优点，所以纳米多孔氧化硅薄膜正适合应用在这种微电子工艺中。.本文中采用等离子体增强化学气相沉积法（PECVD），以六甲基二硅氧烷(HMDSO)为单体，并通入氧气、氩气，再加入少量的有机物质，通过辉光放电的方式形成等离子体，从而在玻璃基材表面沉积制备出氧化硅薄膜，再在高温下进行热处理，使氧化硅薄膜中的碳氢键等有机组分被除去，形成空隙，从而降低其介电常数；同时，采用超声原子力系统（UAFM）对氧化硅薄膜的弹性模量进行无损检测。主要研究工作如下：.（1）通过改变单体与氧气的比例、沉积时间、沉积功率等实验条件，制备出不同介电常数的纳米多孔氧化硅薄膜，再对制备出的氧化硅薄膜在进行热处理，最终制备出K<1.9纳米多孔氧化硅薄膜。.（2）利用UAFM系统测试悬臂梁、参考试样、试验样品的谐振频率，并结合悬臂梁接触刚度模型的特征方程，利用MATLAB软件计算参考试样和实验样品的接触刚度，最后利用参考法计算出被测试样的弹性模量，实现对氧化硅薄膜弹性模量的无损检测。.（3）利用构建的UAFM系统检测了多孔氧化硅的超声幅值成像，不同频率对图像的明暗对比有影响，并分析了参数对图像的影响。结果分析表明，幅值成像能反映弹性性能。.(4)利用有限元方法对接触模型、超声原子力显微镜悬臂梁的振动、笔记本包装的振动等进行分析，对实验结果分析有指导性作用。