Laser-Assisted Atomic Layer Etching of Semiconductors and Nanomaterials

用于从晶片表面去除层的蚀刻工艺在半导体行业中无处不在。随着电子制造进入原子尺度区域，开发能够非常严格地控制尺寸变化的蚀刻工艺势在必行。原子层刻蚀(ALET)是一种非常有前途的新兴方法。掺入激光照射可以控制和显著增强这一过程。该奖项支持基础研究，以研究激光辅助ALET的机制。这项研究有可能提供一种手段，以单分子层的精度调节目标材料的尺寸，而不会对邻近结构造成损害。激光诱导的ALET将使纳米结构材料的尺寸变化最小化，从而保持加工序列的保真度。该项目成果具有推动纳米制造的潜力，使原子电子时代的关键应用成为可能。因此，这项工作的结果将有利于美国的经济和社会。这项研究涉及多个学科，包括激光化学加工、电子学纳米制造、材料科学和在线工艺诊断。材料加工和表征相结合的方法将为本科生和研究生提供重要的机会，使他们在纳米科学和工程方面获得令人兴奋的研究经验和最先进的培训，重点是代表不足的群体的参与。激光辅助化学蚀刻可以通过连续的自限反应来控制超薄材料层的去除。表面处理实验与分析诊断相结合，弥合了对Alet机制的化学和物理方面的理解的科学鸿沟，包括气相和表面反应。这项研究将通过在不同压力和流速下应用紫外线激光光源来检测前体蚀刻气体的解离，测量产生的自由基的浓度并将其与表面覆盖率进行关联。在不同的入射波长、脉冲宽度和能量密度下，研究了靶材料和吸附原子的激光诱导激发对原子层去除的影响。激光辅助Alet的概念将扩展到通过针尖纳米刻蚀实现过渡金属二卤化物(TMDC)薄膜和石墨烯的逐层刻蚀。在线光谱学将探索激光诱导解离过程、加工激光与目标材料的耦合以及脱附过程的机制。ALET的激光激活也将作为一种手段来建立与等离子体介导的工艺兼容和补充的低温蚀刻工艺。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Etching processes for removal of layers from the surface of wafers are ubiquitous in the semiconductor industry. As the electronics manufacturing enters the atomic scale regime, it is imperative to develop etching processes that offer extremely tight control of the size variability. A highly promising emerging approach to this end is the Atomic Layer Etching (ALEt). Incorporation of laser irradiation can control and substantially enhance this process. This award supports fundamental research to investigate the mechanisms of laser-assisted ALEt. The research has the potential to provide the means to regulate the target material dimensions with monolayer accuracy without inflicting damage on the neighboring structures. The laser-induced ALEt will minimize changes in the dimensions of nanostructured materials, thereby preserving the fidelity of the processing sequence. The project outcome has the potential to advance nanomanufacturing by enabling key applications in the atomic electronics era. Therefore, results from this work will benefit the U.S. economy and society. The research involves multiple disciplines, including laser chemical processing, electronics nanofabrication, materials science, and on line process diagnostics. The coupled materials processing and characterization methodology will provide significant and presently unavailable opportunities for undergraduate and graduate students to have exciting research experiences and state-of-the-art training in nanoscience and engineering with emphasis on the participation of underrepresented groups. Laser-assisted chemical etching can control the removal of an ultra-thin layer of material using sequential self-limiting reactions. The combination of surface processing experiments with analytical diagnostics bridges a scientific gap in the understanding of chemical and physical aspects of the ALEt mechanisms including gas phase and surface reactions. The research will examine the dissociation of precursor etchant gases by applying ultraviolet laser sources under different pressures and flow rates, measure and correlate the concentrations of the produced radicals to the surface coverage. Work will be conducted to investigate the effect of laser-induced excitation of the target material and the adsorbed atoms on the atomic layer removal under different incident irradiation wavelengths, pulse durations and energy densities. The laser-aided ALEt concept will be extended to accomplish layer-by-layer etching of transition metal dichalcogenide (TMDC) films and graphene via tip-based nanopatterning. On line spectroscopy will probe the mechanisms of the laser-induced dissociation process, the coupling of the processing laser to the target material and the desorption process. The laser activation of ALEt will also be explored as a means to establish a low temperature etching process compatible and complementary to plasma-mediated processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.