Thin Film Fracture and Decohesion in Micro- and Nano-Patterned Devices

提案ID：0408487PI：Sottos，Nancy组织：伊利诺伊大学香槟分校标题：微纳图案化设备中的薄膜破裂和脱粘这项研究重点是与通过软光刻方法制造的微纳图案化薄膜器件相关的独特的破裂和脱粘问题。软光刻包括一组技术，如微接触印刷(m-CP)和纳米转移印刷(n-TP)，它们使用柔性弹性印章在衬底表面形成自组装单分子层(SAM)的图案。然后，自组装膜可用作选择性蚀刻的抗蚀剂或选择性沉积的模板，以形成最终的薄膜器件。这些添加的图案化方法被用来创建复杂的2-D和3-D结构，其特征尺寸从数百微米到数十纳米不等，在电子、传感器和MEMS中有广泛的应用。提出了一种协同实验和计算方法来研究图案化薄膜的表面化学、界面断裂能、加工引起的残余应力和破裂之间的关系。智能价值：该建议中描述的研究将导致几种新的实验和计算工具来量化超薄图案化薄膜中的界面断裂能，而传统的附着力测试很难表征这些界面断裂能。使用激光诱导脉冲加载技术，将在全范围的混合模式动态加载条件下表征薄膜结合强度。激光脉冲吸收产生高幅度、短持续时间的应力波脉冲，以加载薄膜和衬底之间的界面。将开展动态边缘分层试验，以获得界面的起裂和扩展断裂韧性。借助于适当的分析和数值工具来支持实验，实现了与有意义的断裂参数的联系。将发展强大的数值格式，将谱方法与内聚体积有限方法相结合，以精确提取界面断裂韧性。在当前研究下开发的实验和计算工具将提供对图案化薄膜断裂的定量理解，可以指导设计和开发新的油墨、转移化学和用于软光刻制造的下一代器件的印章。广泛影响：该项目集成了涉及薄膜加工、实验力学和数值断裂分析的研究活动，为伊利诺伊大学两名研究生的教育和培训提供了良好的环境。此外，这些学生将成为贝克曼高级科学与技术研究所一个跨学科研究小组的成员，该小组将促进与化学、化学工程和材料科学的其他学生和教职员工进行更广泛的互动。将要求额外的REU补充，以支持两名本科生研究人员在该项目的实验和计算方面的工作。将努力从代表性不足的群体中招聘研究生担任这些职位。专业人员参加了一些外联活动，以增加人才库，招聘和留住本科生和研究生中任职人数不足的学生。

Proposal ID: 0408487PI: Sottos, NancyOrganization: University of Illinois at Urbana-ChampaignTitle: Thin film fracture and decohesion in micro- and nano-patterned devicesThis research focuses on the unique fracture and decohesion problems associated with micro-and nano-patterned thin film devices fabricated via soft lithographic methods. Soft lithography encompasses a group of techniques, such as microcontact printing (m-CP) and nanotransfer printing (n-TP) that use a flexible elastomeric stamp to form patterns of self-assembled monolayers (SAMs) on the surfaces of substrates. The SAMs can then serve as resists for selective etching or templates for selective deposition to form the final thin film device. These additive methods of patterning are used to create complex 2-D and 3-D structures with feature sizes ranging from hundreds of microns to tens of nanometers for a broad set of applications in electronics, sensors and MEMS. A collaborative experimental and computational approach is proposed to investigate the relationships between surface chemistry, interfacial fracture energy, processing induced residual stress, and cracking in patterned thin films.Intellectual Merit: The research described in this proposal will result in several new experimental and computational tools to quantify the interfacial fracture energy in ultra-thin, patterned films that are difficult to characterize by conventional adhesion tests. Thin film adhesive strength will be characterized under a full range of mixed-mode dynamic loading conditions using a laser induced pulsed loading technique. Laser pulse absorption generates high amplitude, short duration stress wave pulses to load the interface between a film and a substrate. A dynamic edge delamination test will be developed to obtain the initiation and propagation fracture toughness of the interface. The link to meaningful fracture parameters is achieved with the aid of appropriate analytical and numerical tools to support the experiments. Powerful numerical schemes that combine spectral methods with cohesive volumetric finite methods will be developed to accurately extract interfacial fracture toughness. The experimental and computational tools developed under the current research will provide a quantitative understanding of patterned film fracture that can guide the design and development of new inks, transfer chemistries, and stamps for the next generation of devices fabricated by soft lithography.Broader Impact: This project integrates research activities involving thin film processing, experimental mechanics and numerical fracture analysis, providing an excellent setting for the education and training of two graduate students at the University of Illinois. Moreover, these students will be part of an interdisciplinary research group at the Beckman Institute for Advanced Science and Technology that will facilitate broader interactions with other students and faculty from Chemistry, Chemical Engineering, and Materials Science. An additional REU supplement will be requested to support two undergraduate researchers to work on both experimental and computational aspects of the project. Efforts will be made to recruit graduate students from underrepresented groups for these positions. The PIs participate in a number of outreach activities to increase the pool, recruit and retain underrepresented students at the undergraduate and graduate levels.