Chemical Vapor Deposition of Metallic Films at Low Temperatures: Precursor Synthesis and Hydrogen-Assisted Reaction Chemistry

该项目旨在更好地了解薄膜生长/沉积，实现金属二硼化物薄膜的化学气相沉积，以及铜、钽和其他金属薄膜的原子层沉积(ALD)，所有这些都是在较低的衬底温度下进行的。科学目标是使用原位光学、质量和电子光谱来了解薄膜形成的化学。该方法包括四个平行的工作：1)将合成新的前体分子，用于使用氢等离子体增强原子层沉积来生长铜、钽和其他金属，以及使用氢等离子体增强CVD来生长ZrB2、MgB2和其他二硼化物合金。2)发展了利用新的前驱体的薄膜生长策略：用氢等离子体增强ALD沉积铜和钽，用热CVD(化学气相沉积)沉积CrB_2，用氢等离子体增强CVD沉积镁B_2。将使用PI最近发现的前驱体Cr(B3H8)2和Mg(B3H8)2来研究CrB2和MgB2的生长。将探索在Si(111)衬底上异质外延生长单晶膜和在ZrB2或CrB2衬底上生长MgB2单晶薄膜，以及以多壁碳纳米管为模板合成ZrB2或CrB2纳米管。3)将使用原位光谱仪分析薄膜的形成途径，以确定控制ALD和CVD过程的机制。表面反应将使用下游质谱学、反射红外吸收、石英晶体微天平、程序升温脱附和俄歇电子能谱进行分析。在适用的情况下，将使用同位素标记(D表示H)。静态(生长后)和动态(生长期间)表面都将被研究，包括使用时间调制的通量。在沟槽衬底上的共形覆盖实验将被用来提取前驱体的表面反应几率，作为温度和原子氢的并发通量的函数。形核、成分和表面粗糙度将使用实时椭圆偏振光谱仪进行研究。4)评估薄膜的结构和性能，包括晶体结构、导电性和作为杂质扩散阻挡层的性能。将进行沉积、退火和分析由Cu/Ta/Si或Cu/CrB2/Si组成的结构，以确定铜在硅中的内扩散。该项目涉及与具有技术相关性的电子/光子材料相关的基础材料科学和化学研究问题，并强调研究和教育的整合。该项目将每年资助4名研究生和1-2名本科生进行暑期项目或高级论文。将利用UIUC Surge(支持工程学中代表不足的群体)和WISE(科学和工程中的妇女)方案，协助扩大代表不足群体的参与。研究成果将通过在国际会议上发表演讲和在科学期刊上发表来广泛传播。将访问IBM、Intel、Novellus或应用材料等工业微电子组织，介绍并讨论加强大学/行业互动的项目成果。该项目由MPS/DMR和MPS/CHE两个司共同支持。*

This project aims for greater understanding of thin film growth/deposition, achievement of new routes to chemical vapor deposition of metal diboride thin films, and atomic layer deposition (ALD) of copper, tantalum, and other metallic films, all at low substrate temperatures. The scientific goal is to understand the chemistry of film formation using in situ optical, mass, and electron spectroscopies. The approach involves four parallel efforts: 1) New precursor molecules will be synthesized that are designed for the growth of Cu, Ta, and other metals using hydrogen plasma enhanced atomic layer deposition, and for the growth of ZrB2, MgB2, and other diboride alloys using hydrogen plasma enhanced CVD. 2) Film growth strategies using the new precursors will be developed: deposition of Cu and Ta by hydrogen plasma enhanced ALD, CrB2 by thermal CVD (chemical vapor deposition), and MgB2 by hydrogen plasma enhanced CVD. CrB2 and MgB2 growth will be investigated using precursors Cr(B3H8) 2 and Mg(B3H8) 2 recently discovered by the PIs. Heteroepitaxial growth of single crystal films of ZrB2 and CrB2 on Si(111) and MgB2 films on ZrB2 or CrB2 will be explored, as well as the synthesis of ZrB2 or CrB2 nanotubes using multi-walled C nanotubes as a template. 3) Film formation pathways will be analyzed using in situ spectroscopies to determine the mechanisms that govern ALD and CVD processes. Surface reactions will be analyzed using downstream mass spectroscopy, reflection IR absorption, quartz crystal microbalance, temperature programmed desorption, and Auger electron spectroscopy. Where applicable, isotopic labeling (D for H) will be utilized. Both static (post-growth) and dynamic (during growth) surfaces will be studied, including the use of time-modulated fluxes. Conformal coverage experiments on trench substrates will be used to extract the surface reaction probability of precursors, as a function of temperature and the concurrent flux of atomic hydrogen. Nucleation, composition, and surface roughness will be studied using real time spectroscopic ellipsometry. 4) Film structure and properties will be evaluated, including crystal structure, electrical conductivity, and performance as impurity diffusion barriers. Deposition, annealing, and analysis of structures consisting of Cu/Ta/Si or Cu/CrB2/Si will be carried out to determine Cu in-diffusion into Si. %%% The project addresses fundamental materials science and chemistry research issues associated with electronic/photonic materials having technological relevance, and emphasizes the integration of research and education. The project will support four graduate students, and 1-2 undergraduates per year conducting summer projects or senior theses. The UIUC SURGE (Support of Under-represented Groups in Engineering) and WISE (Women in Science and Engineering) programs will be utilized to assist with broadening participation by under-represented groups. Research results will be broadly disseminated by presentations at international conferences and by publication in scientific journals. Industrial microelectronics organizations, e.g., IBM, Intel, Novellus, or Applied Materials, will be visited to present and discuss project results to enhance university/industry interactions. The project is co-supported by the MPS/DMR and MPS/CHE Divisions.***