表面等离子体共振的椭偏测量与超薄介质层表征

For ultra thin oxides (d<10nm) on metals, interface performance improvement and optical constant precise determination are critical for microelectronic, integrated optics and aerospace technology. The scientific problem is how to determine precisely the optical and morphological properties of oxides (refractive index n\extinction coefficient k\defects\ interface roughness\ interface adherence quality) when the film thickness is as low as 10nm or less. The key problems: high precision determination of optical constants and thickness of ultrathin films; non-destructivity of the approach; algorithm for mathematical processing of the measurement data. In this project we propose construction of a novel instrument and method which would profit of polarized light reflection and surface plasmon resonance simultaneously which both techniques are very sensitive but use two different physical phenomena, yielding hence two independent sources of information. A platform based on curved Otto configuration frustrated total reflection and ellipsometry is designed and under construction to phase measuring the state of surface plasmon resonance on the interface of metal and ultra thin solid film. Models of relationship between dielectric constant distribution and surface plasmon state and response of polarized light to the surface plasmon resonance will theoretically setup to inversion calculate the optical constant and microstructure of interface. The development and test of the instrument will yield the means for precise and non-destructive determination of the optical constants of ultra thin films(d<10nm) with particular focus on those dielectic deposited on metals. This novel technique will be useful for many modern applications, e.g.microelectronic, aerospace technology, integrated optics.

金属表面超薄介质层(d<10nm)的界面性能改进和光学常数的精确获取对于微电子、光学和空间技术进步有着重要的意义。表面等离子体共振和偏振光反射这两个物理过程对薄膜界面及附近特征非常敏感，本申请拟集成两者的优点，运用椭圆偏振位相测量技术精确表征金属与超薄介质层界面上的表面等离子体共振现象。通过搭建弯曲Otto结构的受抑全反射椭偏测试平台，使其适用于观察和表征超薄固态薄膜界面的表面等离子体，实现偏振态信息对界面状态的高精度、高准确性测试。理论构建表面等离子体态对界面介电常数空间分布关系模型及偏振光对表面等离子体共振态的响应模型，实现反演运算，提取界面特征信息，并确保解的准确性和高精度。该工作将结合测试平台，侧重从理论方法上建立起高效、无损的超薄薄膜(d<10nm)光学常数与界面微结构光学表征方法和流程。相关研究结果将推动高精密薄膜元器件的表征与精确控制能力。

金属表面超薄介质层(d<10nm)的光学常数精确获取对于微电子、光学和空间技术进步有着重要的意义。本课题发展等离子体共振椭偏技术，采用等离子体共振（SPR）增强对超薄膜层光学常数的敏感性，基于椭偏技术提取共振诱导的振幅和相位变化，充分利用SPR和椭偏技术各自优点，提升超薄膜层测试精度。项目组围绕SPR椭偏技术研制过程中的难点问题，发挥我所在光、机、电一体化优势，首先从理论上证明了基于SPR椭偏技术对于实现课题指标的可行性。理论结果表明采用SPR椭偏技术后测试精度大幅度提升，对于~8nm超薄金膜，0.1nm的厚度变化对应共振中心波长漂移8nm；1nm厚度变化对应共振中心波长漂移72nm；在1250nm处折射率变化0.05，Delta变化16°，在此基础上开发了两类SPR椭偏仪：SPR成像椭偏仪和SPR光谱型椭偏仪。.自主搭建SPR成像椭偏仪，采用倾斜成像技术消除图像离焦，自准直仪实现样品重复定位，降低吸收提升光束功率稳定性，基于光栅尺反馈精确控制测试角度，搭建的成像椭偏仪测试结果与标准椭偏仪吻合，在此基础上嵌入Otto结构采用毫米光束激发SPR，获得椭偏参数随气隙厚度的变化曲线，反演获得光学常数。.在光谱型椭偏仪中嵌入Otto结构，采用微米光束激发SPR，实现SPR光谱型椭偏仪。采用微米光束辐照Otto结构实现百纳米级空气隙厚度调控，获得椭偏参数随入射波长、角度的变化曲线，反演获得光学常数。百纳米气隙厚度的精确调控为此技术工程化实现探索有效途径。.由此，项目组自主开发了超薄膜层表征方法、平台及数据处理方法，并制定了测试流程。实验结果表明基于SPR椭偏技术测量超薄膜层（包括厚度小于10nm样品）的厚度测试精度优于0.1nm，折射率测试精度优于0.05。项目执行过程中共发表论文4篇，其中SCI收录2篇，国内核心期刊2篇，申请发明专利4项。项目圆满完成预期成果与技术指标。