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工业中是普遍存在的。随着电子制造进入原子尺度范围，必须开发对尺寸可变性提供极其严格控制的蚀刻工艺。为此，一种非常有前途的新兴方法是原子层蚀刻（ALEt）。激光照射的结合可以控制并大大增强这一过程。该奖项支持基础研究，以调查激光辅助ALEt的机制。这项研究有可能提供一种方法来调节目标材料的尺寸与单层精度，而不会对相邻的结构造成损害。激光诱导的ALEt将使纳米结构材料的尺寸变化最小化，从而保持加工顺序的保真度。该项目的成果有可能通过在原子电子时代实现关键应用来推进纳米制造。因此，这项工作的成果将有利于美国的经济和社会。该研究涉及多个学科，包括激光化学加工，电子纳米纤维，材料科学和在线过程诊断。耦合材料加工和表征方法将为本科生和研究生提供重要的和目前不可用的机会，使他们在纳米科学和工程领域获得令人兴奋的研究经验和最先进的培训，重点是代表性不足的群体的参与。激光辅助化学蚀刻可以使用连续的自限制反应来控制超薄材料层的去除。表面处理实验与分析诊断的结合弥补了对ALEt机制的化学和物理方面（包括气相和表面反应）的理解方面的科学空白。该研究将通过在不同的压力和流速下施加紫外激光源来检查前体蚀刻剂气体的解离，测量所产生的自由基的浓度并将其与表面覆盖率相关联。研究了在不同的入射激光波长、脉冲宽度和能量密度下，激光诱导靶材料和吸附原子的激发对原子层去除的影响。激光辅助的ALEt概念将被扩展到通过基于尖端的纳米图案化来实现过渡金属二硫属化物（TMDC）膜和石墨烯的逐层蚀刻。在线光谱将探测激光诱导解离过程的机制，加工激光与目标材料的耦合和解吸过程。ALEt的激光激活也将被探索作为一种手段，以建立一个低温蚀刻工艺兼容和补充等离子体介导的processes.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的知识价值和更广泛的影响审查标准。

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.