双靶磁控溅射共沉积cuw薄膜及结构与性能研究.pdf

湖南大学 硕士学位论文 双靶磁控溅射共沉积Cu-W薄膜及结构与性能研究 姓名：王瑞 申请学位级别：硕士 专业：材料物理与化学 指导教师：周灵平;彭坤 20080420 双靶磁控溅射共沉积 Cu- W 薄膜及结构与性能研究 II 摘 要 Cu- W 薄膜具有高导热导电性及低的热膨胀系数等优点，广泛应用于微电子 及电子器件领域但铜和钨互不固溶、浸润性差，常规方法很难制得 Cu- W 固溶 体本实验采用双靶聚焦磁控溅射共沉积，制得 Cu- W 亚稳态固溶体薄膜 首先， 通过实验得到薄膜中 W 的原子含量随 W 与 Cu溅射功率比的变化曲线 通过 EDS、XRD、SEM、TEM 等测试，发现 Cu- W 薄膜由 Cu 固溶于 W 或 W 固 溶于 Cu 的亚稳固溶体组成，且随着 W 含量的增加， Cu- W 薄膜依次形成 fcc 结构 的 Cu 基亚稳固溶体、 fcc 和 bcc 结构固溶体的双相区以及 bcc 结构的 W 基亚稳固 溶体，且其晶粒尺寸随着溶质原子浓度的增加而减小分析得到 Cu- W 薄膜亚稳 固溶体的形成是由于溅射出的原子动能足以克服 Cu、W 固溶所需的混合热，以 及溅射过程中粒子的纳米化和成膜过程中引入的大量缺陷造成的。

此外，研究了 不同成分 Cu- W 薄膜形核生长过程中的结构， 发现在 Cu- W 薄膜形核和生长初期， W 呈晶态，而 Cu 呈非晶态，这样有利于克服 Cu 和 W 的正混合热，在随后的生 长过程中，由于溅射粒子的轰击作用，Cu逐渐晶化，与 W 形成亚稳固溶体 其次，讨论了成分对 Cu- W 薄膜粘结性能的影响结果发现，两相区样品的 粘结性能最优通过界面处理工艺对 W 基 Cu- W 薄膜粘结性能的研究发现，衬底 表面未经离子束清洗的样品粘结性能最差，采用离子束辅助轰击对衬底表面注入 W 粒子，可显著提高 Cu- W 薄膜的粘结强度，其临界载荷比经离子束清洗表面处 理的样品大 1 倍以上离子束辅助轰击 W 粒子注入能显著提高 W 基 Cu- W 薄膜 的粘结强度，是因为在中能 Ar ＋离子的辅助轰击下，W 原子可以注入到 Fe 衬底表 层并与 Fe 原子交织在一起， 在膜基界面形成原子尺度上的微观机械结合和扩散结 合同时混合层由于含有大量的 W 原子，其热膨胀性能将更接近于 W 或以 W 为 基的 Cu- W 薄膜，也有利于粘结强度的提高 最后，研究了 Cu- W 薄膜的电性能和热性能。

在电性能方面，由于溶质原子 的加入使晶格产生了畸变，因此 Cu- W 薄膜的电阻率随着溶质原子浓度的增加而 增大在热性能发面， Cu- W 薄膜的热导率远远低于块体材料的热导率，主要是 由于薄膜材料结构中微裂纹的存在以及薄膜边界散射和薄膜内部晶界散射造成 的，有待进一步的研究；它的热膨胀系数基本符合混合规律，实验值明显低于理 论值 关键词：磁控溅射；共沉积；Cu- W 薄膜；微观结构；粘结强度；电性能；热性 能 硕士学位论文 III Abstract Cu- W thin film is uesd widely in the field of Microelectronics and Electronic Devices due to excellent electric thermal conductivity and low thermal expansion. It is rather difficult to obtain Cu- W solid solution due to the insolubility and poor wetting property between Cu and W. In this paper, Cu- W thin films of metastable solid solution were deposited by dual- target magnetron co- sputtering. Firstly, the relationship between at% W and PW/PCu have been obtained through experiments. The structures and micrographs of Cu- W thin films were analyzed by EDS, XRD, SEM and TEM. Results reveal that Cu- W thin films consist of metastable solid solution of Cu in W or W in Cu.The structures vary with W content increasing, which are fcc of W in Cu, (fcc+bcc) two- phase regions and bcc of Cu in W metastable solid solution. The grain size reduces with the content of solute atom increasing. The formation of Cu- W metastable solid solutions attribute to that the atom energy is enough high to overcome the mix- heat and the nano- particles and a great deal of defects interfuse within thin films. In addition, the structures of Cu- W thin films in different growth stages are studied. Results reveal that W is crystal and Cu is non- crystal in the early stage, which is conducive to overcome the mixed heat between Cu and W. In the subsequent growth process, due to sputtering particle bombardment role, Cu gradually crystallized and formed the metastable solid solution with W. Secondly, effects of the component on the adhesive strength of Cu- W thin films are studied. Results reveal that the adhesive strength of two- phase Cu- W thin films is best. The effects of the substrates surface treating technique on the adhesive strength of W- based Cu- W thin film are studied. It is found that the technique of ion beam assistant bombardment implanting W particles can remarkably improve the adhesive property of W- based Cu- W thin films. The critical load is doubled over than the sample only sputter- cleaned by ion beam. The mechanism of ion beam assistant bombardment implanting enhancing the adhesion of W- based Cu- W thin films is analyzed. With the help of mid- energy Ar ＋ ion beam, W atoms can carry on diffusion into the Fe- substrate surface layer, Fe atoms in the substrate surface layer and W atoms interlace with one another, microcosmic mechanical meshing and diffusing combination on atom- scale among the Fe and W atoms through the film- substrate 双靶磁控溅射共沉积 Cu- W 薄膜及结构与性能研究 IV interface can be formed. The wettability and thermal expansion properties of the W atoms diffusion zone contained plentiful W atoms are close to that of pure W or W- based Cu- W film. Finally, the electrical and thermal properties of Cu- W films are studied. In electrical properties, the lattice distortion is produced due to the addition of solute atoms, so the resistance of Cu- W films increase with the content of solute atom increasing. In thermal properties, the thermal conductivity of Cu- W films is far below the bulk materials, it is mainly due to the micro- cracks and scattering of the border and crystal in film; the thermal expansion of Cu- W films in line with the basic rules mixed, which are below the value of theory. Key Words: Magnetron Sputtering; Co- deposition; Cu- W Films; Micro- structure; Adhesive Strength; Electrical Properties; Thermal Properties 双靶磁控溅射共沉积 Cu- W 薄膜及结构与性能研究 VIII 插图索引 图 1.1 单离子束多靶旋转溅射沉积装置的结构示意图… … … … … … … … … … 4 图 1.2 离子束辅助沉积示意图… … … … … … … … … … … … … … … … … … … … 5 图 1.3 双靶磁控溅射装置示意图… … … … … … … … … … … … … … … … … … … 6 图 2.1 薄膜沉积设备系统示意图… … … … … … … … … … … … … … … … … … 1 0 图 2.2 两种光热偏转测试方法… … … … … … … … … … … … … … … … … … … 1 4 图 2.3 压痕法测试原理示意图… … … … … … … … … …。