基于剪应变分布调控的高纯钽微观组织及织构优化定量研究

With the increasing of the integration degree in the IC, metatllization become more and more fine, so, the microstructure and texture of the high-purity tantalum sputtering target used in the IC to fabricate the diffusion-defending layers needs to be improved. Asymmetric rolling has an important effect on the evolution of the microstructure and texture of metals, the essential reason is the additional shear strains are imposed during the asymmetrical rolling. The research project is try to quantitatively investigate the optimization of the microstructure and texture in high-purity tantalum based on the controlling of the distribution of shear strain. The quantitative characterization of the evolution of the microstructure of the high-purity tantalum during the asymmetrical rolling is done by the advanced microstructur analysis technologies. The grain subdivision behavior during the deformation process will be intensively studied. The mechanism of shear strain influencing the microstructure and texture evolution of high-purity tantalum is hoped be clarified in present project. To clarify the the recrystallization mechanism of the asymmetric rolled high-purity tantalum, the microstructure and texture evolution of the asymmetric rolled high-purity tantalum will be systematicaly studied. The research results will contribute to optimise the microstructure and texture of the high-purity tantalum by controlling the distribution of shear strain. Furthermore, the research outcomes have significant science and engineering meanings for the research and development of new process and new forming technology of high-purity tantalum sputtering targets.

随着集成电路集成度不断提高，布线宽度要求越来越细，这对集成电路产业中用于制备扩散阻挡层的高纯钽溅射靶材的微观组织及织构提出了更高要求。异步轧制对于金属的微观组织及织构演变存在重要影响，从本质上来说，该影响是通过异步轧制所引入附加剪切变形而产生。本项目拟开展基于剪应变分布调控的高纯钽微观组织及织构优化定量研究。运用物理模拟方法获得高纯钽异步轧制过程中变形区内剪应变分布规律。综合运用多种先进微观分析和表征技术对异步轧制高纯钽微观组织结构演变进行定量表征。深入研究形变过程中的晶粒分裂行为、阐明剪应变影响高纯钽微观组织及织构演变的作用机理。系统考察异步轧制高纯钽退火过程中的微观组织与织构演变，阐明异步轧制高纯钽的再结晶机制。研究成果对于有效地通过调控剪应变分布来优化高纯钽微观组织及织构、研究和开发高纯钽溅射靶材制备新工艺和新技术具有重要的科学意义和工程意义。

本项目通过引入异步轧制工艺用于高纯钽板的变形加工，实现了高纯钽板微观组织及织构的优化调控。综合运用多种先进微观分析和表征技术，系统地对异步轧制高纯钽微观组织结构演变进行了定量表征。探明了异步轧制过程中高纯钽微观组织与织构及其均匀性演变的定量规律。异步轧制由于优化了高纯钽板轧制过程中沿厚度方向的应变均匀性，从而可有效地改善高纯钽板的织构均匀性。初步阐明了高纯钽在不同轧制方式下变形过程中的晶粒分裂机制。轧制变形过程中纯钽的晶粒分裂行为存在明显的取向相关性，{111}晶粒的分裂程度明显高于{100}晶粒，相应的变形微结构存在明显差异。相比于同步轧制，异步轧制中不同取向晶粒之间的分裂要更为均匀。获得了退火制度对于异步轧制高纯钽微观组织与织构及其均匀性的影响规律，揭示了异步轧制高纯钽的再结晶机制。高纯钽再结晶过程中{100}与{111}晶粒的形成存在一种竞争关系，这种竞争来源于二者储存能差距。回复可调整二者储存能的差异，通过合理控制再结晶前的回复可有效调控纯钽的再结晶微观组织与织构。研究成果对于高纯钽微观组织及织构的优化、研究和开发高纯钽溅射靶材制备新工艺和新技术具有重要的科学意义和工程意义。