Texture and Texture Transformations in Thin Metal Films

金属薄膜中的纹理和纹理变换

• 批准号: 1106223
• 负责人: Shefford Baker
• 金额: $ 39万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1106223&HistoricalAwards=false
• 关键词: Texture; Transformations; Thin; Metal; Films

TECHNICAL SUMMARY: Thin metal films are critical elements in many nano- and micro-fabricated technologies including microelectronics, optics, sensors, and catalysts. Due to dimensional constraints, such films are often found to be textured; that is, the individual metal crystallites comprising the film are preferentially oriented with certain types of crystal planes parallel to the film plane. Since the properties of the film depend strongly on the orientations present, understanding texture is critical to understanding the performance and reliability of devices containing thin films. There is good general agreement on the driving forces leading to texture formation. However existing models predict that only one texture component should occur at equilibrium, while mixed textures are common. To understand this, the kinetics of texture transformations in real films must be understood. In this project, the Baker group will study the kinetics of the transformation from as-deposited to as-annealed texture in thin metal films. Preliminary work suggested that inhomogeneous 3-D stress states that arise in such films may stabilize the mixed texture. To investigate this, the Baker group will produce films with very good control over film structure and chemistry, characterize film structure, including measurements of grain size distributions as a function of orientation, and will determine the volume fractions of the different texture components, and stress states in them, using in-situ synchrotron x-ray diffraction and TEM methods. They will use a high-throughput method that allows them to investigate multiple parameters with every film deposition. Detailed finite element simulations will be conducted to study the stress distributions within individual crystallites, and analytical models will be used to link stress states, kinetic models, and thermodynamic models into a construct that should strongly enhance prediction and control of thin film texture, and therefore properties.NON-TECHNICAL SUMMARY: Thin metal films---metal layers less than one tenth the thickness of a human hair---are essential elements in computer chips, optical systems, catalytic converters, and many other high-tech devices. These films are made up of many tiny metal crystals, called "grains". Because the films are so thin, grains tend to orient themselves so that certain directions in their crystal structure align with the plane of the film. The properties of thin films, and therefore the performance and reliability of devices containing thin films, depend very sensitively on these orientations. This topic has been studied for many years but people do not yet have the ability to predict how a film or a device will behave. The Baker group at Cornell University has proposed that the way that loads are distributed across the grains can stabilize different combinations of orientations. To study this, they will make films, characterize their structure and behavior using sophisticated tools such as the Cornell High Energy Synchrotron Source (CHESS) and will generate computer models to help interpret their results. The knowledge generated in this project will help make it possible to continue to miniaturize the next generation of nanofabricated devices and should help to improve performance and reliability in all devices that contain thin metal films. This project will involve undergraduates at both Cornell and at Houghton College, a small non-PhD-granting institution in upstate New York. Undergraduate participation will enhance both the scientific output of the project and the educational experience of those students. Undergraduates will participate fully in the research, and will present their work in presentations at professional society meetings and in peer-reviewed papers. Houghton students will be advised at Houghton by Prof. Brandon Hoffman, but will spend summers working with the Baker group at Cornell. Baker group graduate students and post-docs are active in outreach activities to area schools and institutions. A benefit of the current project is that images of grain orientation distributions can be quite striking and can often stand on their own as art, making a nice icebreaker for talking about materials science to non-scientists.

技术概要：金属薄膜是许多纳米和微米制造技术的关键元素，包括微电子，光学，传感器和催化剂。由于尺寸限制，通常发现这样的膜是织构化的;也就是说，构成膜的各个金属微晶优先取向为具有平行于膜平面的某些类型的晶面。由于薄膜的性质强烈依赖于存在的取向，因此理解织构对于理解包含薄膜的器件的性能和可靠性至关重要。有很好的一般协议的驱动力导致织构形成。然而，现有的模型预测，只有一个纹理分量应该出现在平衡，而混合纹理是常见的。为了理解这一点，必须理解真实的薄膜中纹理转变的动力学。在这个项目中，贝克小组将研究薄金属薄膜从沉积态向退火态织构转变的动力学。初步工作表明，在这种薄膜中出现的不均匀的3-D应力状态可能会稳定混合纹理。为了研究这一点，贝克小组将生产出对薄膜结构和化学性质有很好控制的薄膜，表征薄膜结构，包括测量晶粒尺寸分布作为取向的函数，并将使用原位同步X射线衍射和TEM方法确定不同织构组分的体积分数和应力状态。他们将使用高通量方法，使他们能够研究每次薄膜沉积的多个参数。将进行详细的有限元模拟以研究单个微晶内的应力分布，并且将使用分析模型将应力状态、动力学模型和热力学模型链接到一个构造中，该构造将极大地增强薄膜织构的预测和控制，从而增强性能。薄金属膜-金属层的厚度不到人类头发的十分之一-是计算机芯片、光学系统、催化转换器和许多其他高科技设备的基本元件。这些薄膜由许多微小的金属晶体组成，称为“晶粒”。由于薄膜很薄，晶粒倾向于自我定向，从而使其晶体结构中的某些方向与薄膜平面对齐。薄膜的性质，以及因此包含薄膜的器件的性能和可靠性，非常敏感地取决于这些取向。这个话题已经研究了很多年，但人们还没有能力预测电影或设备的行为。康奈尔大学的贝克小组提出，载荷在晶粒上的分布方式可以稳定不同的取向组合。为了研究这一点，他们将制作电影，使用康奈尔高能同步加速器光源（CHESS）等复杂工具来表征它们的结构和行为，并将生成计算机模型来帮助解释他们的结果。在这个项目中产生的知识将有助于继续使下一代纳米制造设备的制造成为可能，并应有助于提高所有包含薄金属膜的设备的性能和可靠性。该项目将涉及康奈尔大学和霍顿学院的本科生，霍顿学院是纽约北部一所小型的非博士授予机构。本科生的参与将提高项目的科学产出和这些学生的教育经验。本科生将充分参与研究，并将在专业协会会议和同行评议的论文中介绍他们的工作。霍顿的学生将在霍顿接受布兰登霍夫曼教授的建议，但他们将在康奈尔大学的贝克小组工作一个夏天。贝克集团的研究生和博士后积极参与地区学校和机构的外联活动。当前项目的一个好处是，晶粒取向分布的图像可能非常引人注目，并且通常可以作为艺术独立存在，为非科学家谈论材料科学提供了一个很好的破冰船。