面向硅通孔三维互连技术的多晶硅亚纳米级可控去除机理研究

As a current generation of three-dimensional (3D) interconnect technique, through silicon via (TSV) provides a novel method for the semiconductor chip technology exceeding the physical limitation of 5 nm in line width. Due to its good thermal match and high thermal stability, polysilicon has been as the ideal filling material in TSV process. In this application, the functionalization of TSV structure must be based on the controllable removal of surpluses covering polysilicon material. The high integration and miniaturization in TSV process put forward higher requirements on the polished surface precision and the consistency of gate height. However, the controllable polishing removal of surficial material is facing great challenges since poly-silicon is a heterogeneous material assembled with grain and doped with other elements. Therefore, this project will deeply explore the impact mechanism of crystal structure and doped elements on the tribochemcial removal of silicon atoms by single point removal test combining with molecular dynamics simulation, following the technical route from the single crystal, the amorphous to the polycrystalline structures. On the basis, the process parameters of chemical mechanical polishing (CMP) will be designed accordingly, and the effect of variously typical influence factors on CMP of doped polysilicon will be systematically studied. Then, an energy compound driving model for the tribochemical removal will be established based on thermodynamics and kinetics analysis. As a result, the optimization process on consistent and controllable polishing of the doped polysilicon surface will be proposed to realize the fabrication of sub-nanometer scale precision surface with a steady polishing rate.

新一代硅通孔（TSV）三维互连技术为半导体芯片工艺突破5纳米线宽物理极限的限制提供了全新的途径。多晶硅因良好的热匹配性和热稳定性成为硅通孔工艺理想的填充材料，其过盈覆盖层的可控抛光去除是TSV功能化的前提。TSV的高度集成化和微型化对抛光表面精度和栅极高度一致性提出了极为苛刻的要求，而多晶硅属于晶粒集合异质材料，且含有掺杂元素，因此表面材料的可控去除面临巨大挑战。为此，本项目拟采用单点材料去除研究与分子动力学模拟相结合，循着从单晶、非晶到多晶的技术路线，深入揭示晶体结构和元素掺杂对硅原子摩擦化学剥离的影响机制；在此基础上，针对性设计抛光工艺参数，系统研究各典型因素对掺杂多晶硅化学机械抛光的影响规律，并通过热力学和动力学分析，构建摩擦化学去除能量复合驱动模型，最终为实现稳定抛光速率下亚纳米级表面精度加工，提出掺杂多晶硅异质材料的一致、可控抛光工艺优化措施。

新一代硅通孔（TSV）三维互连技术为半导体芯片工艺突破5纳米线宽物理极限的限制提供了全新的途径。多晶硅因其良好的热匹配性和热稳定性成为硅通孔工艺理想的填充材料，其过盈覆盖层的可控抛光去除是TSV功能化的前提。TSV的高度集成化和微型化对抛光表面精度和栅极高度一致性提出了极为苛刻的要求。而多晶硅属于晶粒集合异质材料，多晶晶粒及非晶成分严重影响多晶硅材料的去除，因此实现表面材料的可控去除面临巨大挑战。为此本项目通过系统研究宏微观下多晶硅材料去除行为与机制，构建原子级材料可控去除模型，提出多晶硅抛光工艺优化措施，实现了多晶硅亚纳米精度表面加工。主要研究进展如下：.（1）探明了晶体结构和工况条件对硅表面原子摩擦化学剥离的影响规律。相关研究成果获得中国摩擦学优秀论文奖（全国每年评选一篇）。.（2）揭示了多晶硅等表面原子级材料的可控去除机理。相关研究成果已发表在ACS nano和Nano Lett等国际期刊，并入选7篇期刊封面或副封面论文。 .（3）调控化学机械抛光参数实现了非晶、多晶硅的亚纳米级表面精度制造。其中一些工艺应用于国内抛光龙头企业的抛光工艺优化，助力国产首台高端抛光装备的成功研发。.（4）构建摩擦化学复合能量驱动去除模型并提出多晶硅表面的CMP优化措施。相关内容作为主要支撑成果之一获得了教育部自然科学一等奖（已完成公示）。.相关研究符合国家高新科技发展的重大战略需求，其成果不仅可以丰富纳米摩擦学的基础理论，而且也有助于推动我国CMP技术和IC制造的发展进程。

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