Systematic Studies of Plasma Reactions on Dynamic Surfaces, Using a Novel Rotating Substrate

使用新型旋转基底对动态表面上的等离子体反应进行系统研究

• 批准号: 0966967
• 负责人: Vincent Donnelly
• 金额: $ 30万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-15 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0966967&HistoricalAwards=false
• 关键词: Systematic; Studies; Plasma; Reactions; Dynamic

0966967DonnellyIntellectual MeritThese studies will systematically investigate selected chemistry occurring at the boundary between a gaseous plasma discharge and the walls of the reactor that contains the plasma. Such basic knowledge of the plasma-wall boundary is lacking in plasma science and is critically needed for control of plasma processing such as etching for fine-line pattern transfer in silicon integrated circuits and other future nano-technology. To gain access to the plasma-wall boundary, a cylindrical substrate within the plasma chamber wall will be rapidly rotated, allowing portions of the surface to be periodically exposed to the plasma and then analyzed. Previously, we used this ?spinning wall? method to investigate surface recombination reactions of oxygen atoms in an oxygen plasma and chlorine atoms in a chlorine plasma, and as well as surface reactions that form chlorine oxide and chlorine dioxide in plasmas with mixtures of oxygen and chlorine. The new studies will focus on four topics of critical importance to understanding and controlling chemistry at surfaces immersed in plasma: 1) What is the role of weakly bound stable adsorbates such as Cl2 on recombination of Cl atoms? We previously found that physisorbed Cl2 blocks sites for Cl recombination. We will extend the study to a much wider range of conditions and investigate other suspected cases such as Br2 and fluorocarbons. 2) How widespread is, and what is the mechanism for, catalyzed recombination by trace metals, as we recently discovered for O in the presence of sub-monolayer coverages of copper? The oxidation-reduction mechanism proposed for copper will be tested with other metals, and recombining atoms. 3) The relative importance of the two prevailing mechanisms for surface reactions (the so-called Langmuir-Hinshelwood or delayed reaction vs. the Eley Rideal or prompt reaction) will be determined for selected atoms and small molecules. Except for hydrogen atoms on pristine surfaces, such information is almost completely lacking. 4) What are the roles of ion and electron bombardment on surface chemical reactions? Positive ions bombarding the surface can create or destroy reaction sites, while electron bombardment can cause decomposition of adsorbed layers, as well as create negative ions and reduce catalytic activity of higher oxidation states of trace metals. The proposed work will be an extremely challenging, basic research project that is critical for improving our understanding of plasma-surface interactions with an emphasis on plasmas used for etching of nano-scale features in integrated circuits and other future devices. Broader ImpactsThe proposed work will provide challenging projects for two graduate student and one or more undergraduates, with rich scientific and educational payoffs, as well as technological advances. While it will improve our understanding of surface reactions under complex plasma conditions, it will also contribute to diverse areas such as space physics, combustion chemistry, catalysis, and atmospheric heterogeneous reactions. In addition, the new methods for isolating such complex reactions have broad implications for and potential impact on these diverse areas, as well as basic surface science. Several outreach activities are planned, including involving a high school teacher in the research, and the participation by undergraduate students through programs such as the Research Experience for Undergraduates (REU) at UH. Finally, the participation of underrepresented students (more than half of the University of Houston undergraduate students are minorities) will be pursued.

这些研究将系统地调查在气体等离子体放电和包含等离子体的反应器壁之间的边界处发生的选定化学。等离子体科学中缺乏此类等离子体壁边界的基本知识，并且对于控制等离子体处理（例如硅集成电路中的细线图案转移蚀刻和其他未来纳米技术）至关重要。 为了接近等离子体壁边界，等离子体室壁内的圆柱形衬底将快速旋转，允许表面的部分周期性地暴露于等离子体，然后进行分析。以前，我们用这个？旋转墙研究氧等离子体中的氧原子和氯等离子体中的氯原子的表面复合反应以及在具有氧和氯的混合物的等离子体中形成氯氧化物和二氧化氯的表面反应的方法。新的研究将集中在四个对理解和控制浸入等离子体表面的化学至关重要的主题上：1）弱结合的稳定吸附物（如Cl 2）对Cl原子的重组有什么作用？ 我们以前发现，物理吸附氯块网站氯重组。我们将把这项研究扩展到更广泛的条件，并调查其他疑似病例，如溴和碳氟化合物。2)有多普遍，是什么机制，催化重组的微量金属，我们最近发现的O在存在下的亚单层覆盖的铜？对铜提出的氧化还原机制将用其他金属和重组原子进行测试。3)对于选定的原子和小分子，将确定表面反应的两种主要机制（所谓的朗缪尔-欣谢尔伍德或延迟反应与埃利-里德尔或迅速反应）的相对重要性。 除了原始表面上的氢原子，这些信息几乎完全缺乏。4)离子和电子轰击在表面化学反应中的作用是什么？轰击表面的正离子可以产生或破坏反应位点，而电子轰击可以引起吸附层的分解，以及产生负离子并降低痕量金属的较高氧化态的催化活性。 拟议的工作将是一个极具挑战性的基础研究项目，对于提高我们对等离子体表面相互作用的理解至关重要，重点是用于蚀刻集成电路和其他未来设备中纳米级特征的等离子体。 更广泛的影响拟议的工作将提供两个研究生和一个或多个本科生具有挑战性的项目，具有丰富的科学和教育回报，以及技术进步。虽然它将提高我们对复杂等离子体条件下表面反应的理解，但它也将有助于空间物理，燃烧化学，催化和大气多相反应等不同领域。 此外，分离这种复杂反应的新方法对这些不同领域以及基础表面科学具有广泛的影响和潜在的影响。计划开展几项外联活动，包括让一名高中教师参与研究，以及通过UH的本科生研究经验（REU）等项目让本科生参与。最后，将争取代表性不足的学生（休斯顿大学本科生中一半以上是少数民族）的参与。