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.

了解薄膜在高温下的热力学行为是材料科学的基本兴趣，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。对于数字间换能器的高熔点BCC金属电极，特别是在350°C以上高温应用的压电基板上，所发生的过程缺乏基本知识，因此这是SAW技术面临的关键挑战。本项目的主要目的是研究在ca3taga3si2o14衬底（Catangasite， CTGS）上溅射沉积高温稳定的BCC W和Mo金属薄膜的热力学行为。CTGS是一种相对较新的压电材料，具有较高的热稳定性，适用于创新的高温SAW温度传感器。然而，目前还没有关于这种金属薄膜在CTGS上的热机械行为的基础研究，而这对于理解这种SAW传感器在高温范围内的运行或降解行为至关重要。因此，将利用基于激光曲率测量方法（弯曲光束）研究薄膜-衬底复合材料在薄膜生长期间和沉积过程后，在热循环至约700℃时的应力演化和应力松弛。由于考虑到这些平均晶粒尺寸< 100 nm的技术上适用的纳米晶材料中可能发生的破坏过程，计划对微观结构演变及其对薄膜应力的影响进行详细研究。为此，将通过不同的分析方法，如薄膜x射线衍射、扫描和透射电子显微镜、聚焦离子束技术、原子力显微镜等来证实其微观结构。本研究的重点是基于W. D. Nix、E. Arzt、C. V. Thompson、H. Gao等人多年的工作，从根本上理解并模拟薄膜-衬底复合材料的变形和蠕变过程，这些过程依赖于沉积参数或更确切地说，是固有应力和温度。