基于掺杂的共振吸收飞秒激光高效率选择性微纳加工

Femtosecond laser has many unique characters, such as high flexible, non-polluting, non-contact, nonlinear absorption, which make it an attractive option for cross-scale micro/nano-machining. However, the balance between quality and efficiency is still a bottleneck need to be solved. At present, by adjusting the temporal and spatial energy distribution, the transient localized photon and electron dynamics can be controlled, thus femtosecond laser micro/nano-machining efficiency can be enhanced but still not enough. In fact, despite laser field, the physical properties of targets, such as the bandgap of transparent materials, crystalline imperfections, chemical bonds of polymer molecules, also have unneglectable influences on photon absorption and material phase change, thus affect the quality and efficiency of femtosecond laser micro/nano-machining. This project will be focused on the improvement of both laser field and material properties and the development of a novel doping-based femtosecond laser machining method. Resonant photon absorption effect can be achieved by doping materials with impurities including rare earth elements and polymers, and finally high-throughput selective femtosecond micro/nano ablation can be attained. Through a systematic research into doping-based resonant absorption femtosecond laser ablation method, the physical mechanisms and the effect laws can be revealed, and the ablation efficiency can be increased by dozens or even hundreds of times.

飞秒激光因灵活、无污染、无接触、非线性吸收等特点成为理想的微/纳制造工具之一，但存在跨尺度加工时质量和效率难以兼顾的瓶颈问题。目前人们通过调节飞秒激光的空间及时间能量分布，调控激光光子与材料电子的瞬时局部作用，有效的提高了飞秒激光加工质量与效率，但仍然不能满足需求。事实上，除了作为加工工具的激光光场，加工对象- - 材料本身的物性，如透明材料的禁带宽度、晶体的晶格缺陷、聚合物分子的化学键等，也能极大影响光子的吸收及材料的相变，从而影响加工质量与效率。本项目提出基于掺杂产生共振吸收的激光加工新方法，这也是首次从材料物性改变的角度来改善激光与物质相互作用，通过在玻璃、晶体、陶瓷、聚合物等材料中掺杂稀土元素或高分子等掺杂物，产生对光子的共振吸收效果，实现高效率选择性微/纳加工。通过系统研究基于掺杂的共振加工方法，揭示掺杂改善飞秒激光加工效率的物理机制和影响规律，以期数十倍至数百倍地提高加工效率。

本项目提出基于掺杂产生共振吸收的激光加工新方法，这是从材料物性改变的角度来改善激光与物质相互作用，通过在玻璃、晶体、聚合物等材料中掺杂稀土元素或金属离子等掺杂物，产生对光子的共振吸收效果，实现掺杂共振吸收效率相比于无掺杂情形提高1.6-4.9倍。通过系统研究基于掺杂的共振加工方法，揭示掺杂改善飞秒激光加工效率的物理机制和影响规律。该成果可应用于核心集成电路芯片和LED芯片封装工艺，提高集成电路电荷层间迁移速度以及优化芯片散热性能，优化LED芯片电流密度分布的均匀性，实现超大电流密度芯片。研究过程中，还发现当飞秒激光能量控制在合适范围内，可实现非热修补纳米尺度缺陷，该成果有望应用于薄膜生长过程，实现高质量金刚石、GaN等下一代半导体材料制备。