Stress relaxation and creep analysis of high temperature thin film materials on CTGS substrates

CTGS 基底上高温薄膜材料的应力松弛和蠕变分析

• 批准号: 273892103
• 负责人: Dr. Gayatri Rane, Ph.D.
• 金额: --
• 依托单位: Max-Planck-Institut für Intelligente Systeme
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/273892103?language=en
• 关键词: Stress; relaxation; creep; analysis; temperature

The understanding of the thermomechanical behaviour of thin films at high temperatures is of fundamental interest in material science and a crucial aspect for improving the operation temperature, reliability and lifetime of modern high-temperature surface acoustic wave (SAW) devices. There is a lack of fundamental knowledge about the processes occurring in high melting BCC metal electrodes for interdigital transducers especially on piezoelectric substrates for high-temperature application above 350 °C and as such is the key challenge faced in SAW technology. The main goal of this project is to study the thermomechanical behaviour of sputter deposited high-temperature-stable metallic thin films of BCC W and Mo on Ca3TaGa3Si2O14-substrates (Catangasite, CTGS). CTGS is a relatively new piezoelectric material of high thermal stability that makes it suitable for innovative high-temperature SAW based temperature sensors. However, there is no fundamental study regarding the thermo-mechanical behaviour of such thin metallic film on CTGS which is essential for understanding the operation or degradation behaviour of such SAW sensors in the high temperature range. For this reason the film stress evolution as well as stress relaxation will be studied on the film-substrate composites by means of a laser-based curvature measuring method (bending-beam) both during the film growth and after the deposition process upon thermal cycling up to a temperature of about 700 °C. A detailed study of the microstructural evolution and its effect on the film stresses is planned owing to concerns regarding damaging processes that can occur in these technologically applicable nanocrystalline materials with average grain size < 100 nm. For this purpose, the microstructure will be corroborated by means of different analytical methods such as thin film X-ray diffraction, scanning and transmission electron microscopy, focussed ion beam technique, atomic force microscopy. The focus of the study is to understand fundamentally and to model the deformation and creep processes in the film-substrate composites in dependence of both deposition parameters or rather intrinsic stress and temperature based on the years of work of W. D. Nix, E. Arzt, C. V. Thompson, H. Gao and others.

对薄膜在高温下的热机械行为的理解是材料科学的根本利益所在，也是提高现代高温表面声波（SAW）器件的工作温度、可靠性和寿命的关键方面。有关叉指换能器的高熔点 BCC 金属电极，特别是用于 350 °C 以上高温应用的压电基板的工艺的基础知识，因此是 SAW 技术面临的主要挑战。该项目的目的是研究 Ca3TaGa3Si2O14 基板（Catangasite，CTGS）上溅射沉积的 BCC W 和 Mo 高温稳定金属薄膜的热机械行为，CTGS 是一种相对较新的高热稳定性压电材料，使其适合创新。然而，目前还没有关于 CTGS 上这种金属薄膜的热机械行为的基础研究，这对于理解其工作原理至关重要。因此，将通过基于激光的曲率测量方法（弯曲梁）研究薄膜-基底复合材料上的薄膜应力演变和应力松弛。由于担心这些技术中可能发生的破坏过程，因此计划对薄膜生长过程中以及热循环至约 700 °C 的沉积过程后进行微观结构演变及其对薄膜应力的影响的详细研究。适用的为此，将通过薄膜 X 射线衍射、扫描和透射电子显微镜、聚焦离子束技术、原子力聚焦显微镜等不同的分析方法来证实平均晶粒尺寸 < 100 nm 的纳米晶材料。这项研究的目的是从根本上理解薄膜-基底复合材料中的变形和蠕变过程，并根据沉积参数或基于多年的内在应力和温度来模拟变形和蠕变过程。 W.D.Nix、E.Arzt、C.V.Thompson、H.Gao 等人的工作。