Local confined laser-induced plasmas for direct writing of low damage patterns by precise reactive etching

随着用于扩展表面和薄膜功能的集成度和结晶度的提高，需要新材料，但也需要用于局部改性、图案化和沉积的新的创新技术。在过去的几年里，激光技术的发展可以提高激光加工的精度，以实现新的应用。目前的激光加工优先利用物理过程，如激光诱导的熔化和蒸发以及烧蚀。该项目的目标是研究激光诱导反应等离子体（LIP），并评估它们用于极高质量和低缺陷密度表面的微加工。LIP和表面之间的相互作用机制可以是化学或物理性质的，然而迄今为止已经研究了典型的物理相互作用。因此，我们专注于激发的化学反应自由基的激光诱导等离子体，应采用局部化学自由基蚀刻的焦点下的一个特定形状的激光束的产生。要回答的主要问题涵盖以下领域：（i）沿表面引导脉冲的高强度激光沿着而不损伤表面，同时能够形成近表面LIP，（ii）优选在大气压下通过激光诱导等离子体从含有合适前体分子的气体混合物产生反应性自由基，以及（iii）LIP产生的活性物质向样品表面的运输以及它们与样品表面的化学反应。通过实验工作的结果，应该完成的研究表面改性和蚀刻依赖于LIP工艺参数和调查的形成，运输和衰减的反应产物的优先光学原位诊断被用来暴露所涉及的过程，并建立一个机制的激光诱导等离子体蚀刻。对选定过程的模拟应有助于验证这些过程和机制的相关性。这种激光诱导的反应等离子体可以实现用于各种应用的表面的局部分辨的化学支持的加工。

With increasing integration and miniaturisation for extending the functionality of surfaces and thin films new materials are required but also new, innovative technologies for local modification, patterning and deposition are requested. Within the last years laser technologies have been developed to increase the precision of laser machining for enabling new applications. The current laser processing preferentially makes use of physical processes like laser-induced melting and evaporation and ablation. The goal of the proposed project is to investigate laser induced reactive plasmas (LIP) and evaluate them for micromachining of surfaces with an extremely high quality and a low defect density. The interaction mechanism between the LIP and surfaces can be of chemical or physical nature however typically physical interactions have been investigated until now. Hence, we focus on the generation of excited chemical reactive radicals by laser induced plasmas that should be employed for local chemical radical etching beneath the focal point of a particular shaped laser beam. Main questions to be answered cover the areas of (i) guiding of the pulsed, high intense laser light along the surface without surface damage and enabling near surface LIP formation at the same time, (ii) generation of reactive radicals from a gas mixture containing suitable precursor molecules by laser induced plasmas preferentially at atmospheric pressure, and (iii) transport of the LIP generated reactive species to and chemical reaction of them with the samples surface. By the results of the experimental work that should be accomplished by studying the surface modification and etching in dependence on LIP process parameters and investigating the formation, transport and decay of reactive products by preferentially optical in situ diagnostics are utilized to expose the involved processes and establish a mechanism of laser induced plasma etching. The simulation of selected processes should provide help for verifying the relevance of these processes and mechanism. Such laser induced reactive plasmas could enable locally resolved, chemical supported machining of surfaces for a variety of applications.