A New-Class of Molecularly-Engineered Nanoporous Dielectric Materials for Insulation in Device Wiring for Integrated Circuits

一种新型分子工程纳米多孔介电材料，用于集成电路器件布线的绝缘

• 批准号: 0519081
• 负责人: Ganpati Ramanath
• 金额: $ 36.83万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0519081&HistoricalAwards=false
• 关键词: New; Class; Molecularly; Engineered; Nanoporous

This project aims for a new strategy to develop a unique class of nanoporous low permittivity Si-C-H-O dielectric material with built-in thermochemical and mechanical stability, and enable its integration with Cu wiring in integrated circuits without using a separate interfacial layer. Rapid Cu diffusion into adjacent insulating dielectric material and poor Cu-dielectric interfacial adhesion are major issues in device wiring in electronic circuits. Typically, 10-20 nm-thick transition-metal based interfacial barrier layers are used to circumvent the problem. Such thick barrier layers cannot be used in sub-50-nm devices because they decrease the space meant for low-resistivity Cu and neutralize the main advantage of Cu wiring. Ultrathin (e.g., 3 nm) barriers required of these materials are not easy to deposit by conventional methods, especially to conformally coat high depth-to-width aspect ratio features common in multilevel wiring. Intellectual merit: Self- assembled molecular nanolayers (SAMs) offer potential to overcome shortcomings of conventional barriers while enhancing the chemical and mechanical integrity of the Cu-dielectric interface. This project seeks to integrate low-polarizability organosilane SAMs into porous dielectrics during synthesis and develop an understanding of the electrical and mechanical properties, and chemical and thermal stability, to enable the direct integration of this material with Cu. The approach involves incorporating (a) chemical-attack-inhibiting moieties on external and internal surfaces and (b) molecular bridges and ordered pores to mechanically reinforce porous dielectrics. Specific objectives are to: (i) Synthesize barrier-less dielectrics through the incorporation of pore-passivating and adhesion-enhancing molecular moieties into silica-based porous dielectrics; (ii) Mechanically reinforce the porous dielectric by creating ordered pores, and molecular bridging of pore walls by cross-linking low-polarizability organosilanes; (iii) Characterize the effects of the above strategies on dielectric properties, thermal and chemical stability, resilience to Cu-diffusion, and Cu-dielectric interfacial adhesion; and (iv) Understand and optimize the effects of molecular termini, chain length, and fraction of intra-pore molecular crosslinking, and processing parameters on properties. To achieve the above, organosilanes with Cu immobilizing, hydrophobic, or cross-linkable termini will be introduced into micellar templates used in sol-gel synthesis of porous silica, and integrated with the dielectric during gelation and post-treatments. Processing-structure-chemistry-property relationships will be revealed through a combination of electrical tests during thermal annealing in controlled ambients, four-point-bend adhesion tests, nanoindentation, atomic force microscopy, x-ray photoelectron spectroscopy, and transmission electron microscopy.Broader impact: The success of this approach could revolutionize wiring design and fabrication for integrated circuits with sub-50-nm devices by obviating interfacial barrier layers between metals and dielectrics. The new knowledge gained from this study will provide atomistic insights on key properties of molecularly engineered porous dielectrics, aid in combining nanostructure self-assembly with device fabrication, and contribute towards bridging micro- and nano-device technologies. The project will also provide a unique opportunity for interdisciplinary training of graduate and undergraduate students through research in molecular self-assembly, sol-gel processing, materials characterization, and device fabrication and testing. Collaborative interactions with IBM will enrich the students' learning experience. A summer internship for two high-school teachers is planned to create and share demonstrations for use in their classrooms. This new activity will complement ongoing visits and reverse-visits to high-schools in the capital region and Rensselaer, contribute to increasing students' awareness on self-assembly and nanodevices and their connection with applied physics and chemistry, and kindle students' interest in science and engineering. The research will be integrated in the self-assembly and molecular nanostructures of a Nanostructured Materials course taught by the PI through an interactive web-module.

该项目旨在开发一种独特的纳米多孔低介电常数Si-C-H-O介电材料，具有内置的热化学和机械稳定性，并使其与集成电路中的Cu布线集成，而无需使用单独的界面层。Cu向相邻绝缘电介质材料中的快速扩散以及Cu-电介质界面粘附性差是电子电路中的器件布线中的主要问题。通常，使用10-20 nm厚的基于过渡金属的界面阻挡层来规避该问题。这种厚的阻挡层不能用于亚50纳米器件，因为它们减少了用于低电阻率Cu的空间，并抵消了Cu布线的主要优点。超薄（例如，这些材料所需的阻挡层不容易通过常规方法存款，特别是不容易共形地涂覆多层布线中常见的高深宽比特征。智力优点：自组装分子纳米层（SAM）提供了克服常规屏障的缺点同时增强Cu-电介质界面的化学和机械完整性的潜力。该项目旨在将低极化率有机硅烷自组装膜在合成过程中整合到多孔硅中，并了解其电学和机械性能以及化学和热稳定性，以使这种材料与Cu直接整合。该方法包括将（a）化学攻击抑制部分的外部和内部表面和（B）分子桥和有序的孔，以机械增强多孔陶瓷。具体目标是：（i）通过将孔钝化和粘附增强的分子部分结合到基于二氧化硅的多孔介电层中来合成无阻挡层介电层;（ii）通过产生有序孔和通过交联低极化率有机硅烷的孔壁的分子桥接来机械地增强多孔介电层;（三）说明上述策略对介电性能、热稳定性和化学稳定性、对铜扩散的恢复力以及铜-电介质界面粘附力的影响;以及（iv）了解并优化分子末端、链长、孔内分子交联分数以及加工参数对性能的影响。为了实现上述目标，将具有Cu固定、疏水或交联末端的有机硅烷引入到用于多孔二氧化硅的溶胶-凝胶合成的胶束模板中，并在凝胶化和后处理期间与电介质集成。通过在受控环境中进行热退火过程中的电气测试、四点弯曲附着力测试、纳米压痕、原子力显微镜、X射线光电子能谱和透射电子显微镜，将揭示工艺-结构-化学-性能之间的关系。这种方法的成功可能会彻底改变布线设计和制造的集成电路与低于50-纳米器件，消除了金属和硅之间的界面阻挡层。从这项研究中获得的新知识将为分子工程多孔陶瓷的关键特性提供原子论见解，有助于将纳米结构自组装与器件制造相结合，并有助于桥接微型和纳米器件技术。 该项目还将通过分子自组装、溶胶-凝胶处理、材料表征以及器件制造和测试方面的研究，为研究生和本科生的跨学科培训提供独特的机会。与IBM的协作互动将丰富学生的学习体验。计划为两名高中教师提供暑期实习机会，以创建和分享在课堂上使用的演示。这项新活动将补充对首都地区和伦斯勒高中的持续访问和反向访问，有助于提高学生对自组装和纳米器件及其与应用物理和化学的联系的认识，并激发学生对科学和工程的兴趣。该研究将通过互动网络模块整合到PI教授的纳米结构材料课程的自组装和分子纳米结构中。