Gold Films by Atomic Layer Deposition: Precursor Design, Synthesis, Evaluation and Optimization in Deposition

原子层沉积金膜：沉积前驱体设计、合成、评估和优化

• 批准号: RGPIN-2014-06250
• 负责人: Barry, Sean
• 金额: $ 2.48万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=632491
• 关键词: Gold; Films; Atomic; Layer; Deposition

Gold films are of significant interest in the thin film community. Applications for gold thin films range from sensor interfaces (due to gold's chemical inertness and enhanced surface plasmon) to metamaterials (gold's negative permeability at visible wavelengths). Gold is typically produced as a thin film by sputtering or evaporation, but these techniques suffer line-of-sight deposition issues: shadow masking and lack of control over the deposition rate at nanometre thicknesses. Chemical vapour deposition (CVD) and atomic layer deposition (ALD) have been main themes of research in my group for a decade. We have had great success designing ligand systems for the deposition of oxides (aluminium, gallium, and indium) as well as metals (particularly copper). My group's experience with synthesis of group 11 compounds and their thermolysis pathways gives us the occasion to understand the mechanistic chemisorption and decomposition of similar compounds. Our ever-developing catalogue of ligands gives us an opportunity to explore some novel gold precursors and their thermal and surface chemistries, as well as to undertake the study of existing gold compounds that have been developed for purposes other than vapour deposition. For example, catalysis chemistry is rich with Au(I) carbene complexes, similar to the formulation our known gold precursor. One research project will undertake the testing of previously-synthesized and known compounds of Au(I). As an example, our research has defined a class of N-heterocyclic carbene (NHC) compounds: R2-NHC-M-N(SiMe3)2, where the “R” group is bound to the nitrogen of the NHC. The compound iPr2-NHC-Au-N(SiMe3)2 was found to deposit a gold film with a growth rate of 0.10 Å per cycle when subjected to a plasma of hydrogen in argon. The problem with this deposition is that the precursor only provides sufficient vapour pressure for the deposition process at 110°C, but starts to undergo thermal decomposition (to gold metal) at 140°C. This makes a reasonably good CVD precursor, but the precursor's “thermal window” needs to be improved as an ALD precursor. Limitations to our gold deposition research have prevented a systematic study of the effect of altering this R-group on thermal stability and deposition conditions. This grant will allow us to undertake such a study. Similarly, we have previously synthesized a series of iminopyrrolidinate (IP) ligands (R-IP, where R is any propyl or butyl group) that limit the thermal decomposition by preventing two known thermal decomposition pathways: carbodiimide elimination and ß-hydrogen elimination. This has proven to be very successful at extending the thermal stability of both Al(III) and Cu(I) compounds. It is necessary to make this series of compounds with Au(I) to test both thermal stability and deposition conditions. This project will also study the effect of incorporating a coordinating ligand (producing a monomeric compound) or allowing the IP to bridge to produce higher-order oligomers. Ultimately, the research program will have a larger scope, envisioning both Au(I) and Au(III) precursors. For anionic ligands, focus will be on nitrogen-based groups such as amides, amidinates, guanidinates, and iminopyrrolidinates. The coordination sphere of gold (2 for Au(I) and 4 for Au(III)) will also necessitate the inclusion of coordinating ligands. Here, the focus will be on phosphines, NHCs, and acyclic aminocarbenes. The program will include the synthesis and thermal testing of these precursor compounds, as well as development of deposition processes and film characterization. The goal of this research program will be to enable the robust and repeatable deposition of nanometre-thick films of gold over highly complex geometries.

金膜在薄膜界引起了人们的极大兴趣。金薄膜的应用范围从传感器接口（由于金的化学惰性和增强的表面等离子体）到超材料（金在可见光波长下的负渗透性）。金通常通过溅射或蒸发作为薄膜产生，但这些技术遭受视线沉积问题：阴影掩蔽和缺乏对纳米厚度的沉积速率的控制。化学气相沉积（CVD）和原子层沉积（ALD）是我的团队十年来的主要研究主题。我们在设计用于氧化物（铝、镓和铟）以及金属（特别是铜）沉积的配体系统方面取得了巨大成功。我的小组在合成第11族化合物及其治疗途径方面的经验使我们有机会了解类似化合物的化学吸附和分解机制。我们不断发展的配体目录使我们有机会探索一些新的金前体及其热化学和表面化学，以及对现有的金化合物进行研究，这些化合物已被开发用于气相沉积以外的目的。例如，催化化学富含Au（I）碳烯络合物，类似于我们已知的金前体的配方。一个研究项目将对以前合成的和已知的Au（I）化合物进行测试。例如，我们的研究已经定义了一类N-杂环卡宾（NHC）化合物：R2-NHC-M-N（SiMe 3）2，其中“R”基团与NHC的氮结合。发现化合物iPr 2-NHC-Au-N（SiMe 3）2在经受氩气中的氢等离子体时以每循环0.10 μ m的生长速率存款金膜。这种沉积的问题在于，前体仅在110°C下为沉积过程提供足够的蒸气压，但在140°C下开始经历热分解（成金金属）。这使得相当好的CVD前体，但是前体的“热窗口”需要作为ALD前体来改进。我们的金沉积研究的局限性，阻止了改变这个R-基团的热稳定性和沉积条件的影响的系统研究。这笔赠款将使我们能够进行这样的研究。类似地，我们先前已经合成了一系列亚氨基吡咯烷（IP）配体（R-IP，其中R是任何丙基或丁基），其通过阻止两种已知的热分解途径来限制热分解：碳二亚胺消除和β-氢消除。这已被证明在延长Al（III）和Cu（I）化合物的热稳定性方面非常成功。有必要用Au（I）制备这一系列化合物以测试热稳定性和沉积条件。该项目还将研究掺入配位配体（产生单体化合物）或允许IP桥接以产生更高阶低聚物的效果。最终，研究计划将有一个更大的范围，设想Au（I）和Au（III）的前体。对于阴离子配体，重点将是氮基基团，如酰胺，脒，胍，和亚氨基吡咯烷。金的配位层（对于Au（I）为2，对于Au（III）为4）也需要包含配位配体。在这里，重点将放在膦，NHC和无环氨基卡宾。该计划将包括这些前体化合物的合成和热测试，以及沉积工艺和薄膜表征的开发。这项研究计划的目标是在高度复杂的几何形状上实现纳米厚金膜的稳健和可重复沉积。