铜合金膜的反常原子迁移及表/界面特征结构表征

Accompanying with the continuous miniaturization of micro-devices, the thickness of the film materials was reduced down to this scale accordingly. Atomic migration on the surface or interface become more and more prominent under the coupled effect of temperature and stress fields. It can usually induce the formation of hillocks on the films surface and, is an issue inevitable for the reliability and stability of related devices. . This project try to modify or control the atomic migration of Cu through adding alloy elements with lower solid solubility, in-situ characterize the evolution of the microstructures and residual stress. Based on the results, the thermodynamic and kinetic models will be established to disclose the mechanism of self-formation of regular polyhedral Cu particles on the film surface, and to uncover the dependence of characteristic morphologies of Cu particles, such as, the size, the shape and the orientation, on the fabrication process parameters, like, the component, the thickness as well as the annealing condition. The results will help us to suppress the atomic migration and the formation of hillocks, or even induce the growth of nano-film/nanoparticle composite structures for novel applications. This will provide us the theoretical and technologic support for high-performance design and the application of relevant micro-devices.

随着微器件特征尺寸的不断小型化，所用薄膜材料的厚度已降至微纳尺度，温度场和应力场耦合作用下薄膜表、界面物质迁移行为愈加凸显，成为相关器件可靠、稳定服役不可规避的问题。. 本项目针对温度及应力场作用下纯铜膜表面易形成丘凸的问题，拟通过掺杂微量低固溶度合金元素调控铜原子的迁移；原位表征其微结构及残余应力的演变行为；结合理论分析揭示合金膜表面自形成规则颗粒的热力学和动力学驱动机制；考察并明确自形成颗粒尺寸、形态、晶体学特征与薄膜成分、厚度、退火条件及外加应力场的内在关联；基于此，有效抑制原子迁移及丘凸的形成或促使纳米膜/纳米颗粒复合结构的可控生长，极大程度提升铜膜的服役效能，为相关器件设计及应用提供理论和技术支撑。

以低固溶度Cu-Zr、Cu-Al-Zr合金膜为研究对象，重点研究了退火过程中聚酰亚胺基体和单晶Si基体上合金薄膜微观结构及残余应力演变行为，取得的主要研究进展如下：（1）发现在退火后合金膜表面会形成大量的多面体颗粒，表征了颗粒的成分、尺寸及晶体结构，分析了合金膜表面颗粒形成与合金膜成分、厚度、退火温度等因素之间的依赖关系，原位观测了合金薄膜表面颗粒析出行为。（2）揭示了退火过程中残余压应力释放与合金薄膜表面颗粒析出之间的关联，提出了通过施加应力场调控合金薄膜表面颗粒析出行为。（3）阐明了力/热场耦合作用下Cu-Zr合金膜表面颗粒析出的机理，明确了表面扩散是退火过程中Cu-Zr合金膜表面颗粒形成的主要原子迁移机制。（4）通过优化铜合金膜成分、厚度、退火工艺及外加应力场，提出了无模板一步制备高性能大比表面积纳米颗粒/纳米薄膜复合结构的方法。. 本项目的研究结果有助于理解低固溶度合金薄膜退火过程中的微观结构演变行为及残余应力释放机制，可为相关材料设计和性能优化提供借鉴。