基于光学散射仪的T型相变存储器三维形貌参数测量

Three-Dimensional Morphology Parameters Measurement of T-Type Phase Change Random Access Memory Based on Optical Scatterometry

T型相变存储器的低功耗、非易失性、高存储密度和高可靠性等优势使其被国际半导体工业协会认为是下一代半导体存储器的主流产品之一。为了保证T型相变存储器制造工艺的可控性,提出了一种基于光学散射的纳米结构三维形貌参数测量方法。基于严格耦合波分析方法建立了T型相变存储器的光学特性模型。分析了待测样品上椭圆偏振光的振幅和相位变化量。用逆散射问题反演求解待测纳米结构的三维形貌参数等信息。利用光学散射仪对T型相变存储器的三维形貌参数进行测量,并将待测参数的提取结果与扫描电子显微镜的测量结果进行对比,验证了光学散射仪在T型相变存储器形貌表征及制造工艺监控上的可行性与有效性。

Ttype phase change memory has the advantages of low power consumption,nonvolatility,high storage density and high reliability,so it is considered by the International Semiconductor Industry Association to be one of the mainstream products of the next generation semiconductor memory.In order to ensure the controllability of the manufacturing process of Ttype phase change memory,a method for measuring threedimensional morphology parameters of nanostructures based on optical scattering is proposed in this paper.The optical characteristic model of Ttype phase change memory is established based on the rigorous coupled wave analysis method.The amplitude and phase change of elliptically polarized light on the sample to be measured are analyzed.The inverse scattering problem is used to solve the threedimensional morphology parameters of the nanostructures to be measured.The threedimensional morphology parameters of Ttype phase change memory are measured by optical scatterometer,and the extraction results of the parameters to be measured are compared with those of scanning electron microscope.The feasibility and effectiveness of optical scatterometer in Ttype phase change memory morphology characterization and manufacturing process monitoring are verified.