论文总字数：22615字

摘 要

顺应微波介质材料的发展以及现代化、微型化、集成化的需求，介电性能优良特别是介电调谐率好的铌酸铋镁Bi_1.5Mg_1.0Nb_1.5O₇薄膜体系的材料受到人们的追捧。因此优化BMN薄膜的制备工艺、研究其介电性能对BMN薄膜的应用和对微波器件的发展具有重要意义。

本实验利用固相烧结法制备陶瓷靶材。采用磁控溅射法，在同一条件下沉积BMN薄膜。以不同的热处理方式制备BMN薄膜。主要研究了退火热处理温度对BMN薄膜晶体的影响和退火热处理时间对BMN薄膜的结构形貌和介电性能的影响。延长热处理温度或时间都能提高薄膜结晶度。但是温度过高或时间过长都可能导致杂相MgNb₂O₆的出现。适当延长热处理时间可以降低BMN薄膜材料的介电损耗，也能起到提高薄膜的介电常数的作用。退火时间的延长特别对BMN薄膜的介电调谐率有着显著提升作用。最佳热处理工艺条件为退火温度750 ^oC下退火45 min。此时薄膜在1.18 MV/cm下，可调率达到27%，介电损耗为0.0043。

关键词：BMN薄膜 磁控溅射 热处理 介电性能 漏电流密度

Abstract

Because of the excellent dielectric properties, especially high dielectric tuning rate, bismuth magnesium niobate Bi_1.5Mg_1.0Nb_1.5O₇ thin films have being popular with people. BMN thin films conform to the development of microwave dielectric materials and the requirements of Modern, miniaturization, integration. Therefore, it is meaningful for the application of BMN film and the development of microwave devices to optimize the preparation technology and study its dielectric properties.

In this experiment, in the first, we have prepared the ceramic target with solid state sintering method. Secondly, we made the magnetron sputtering equipment prepare BMN thin films in the same environment. What’s more using the different ways of heat treatment to prepare the thin films. The study covered the influence of the annealing temperature to the crystals of BMN thin films and the effect of heat treatment time to the surface morphology, Structure, dielectric properties. Besides, they can promote the grain growth of thin films, and improve the thin film crystallinity. However, excessively high temperature and excessively l heat treatment time are likely to result in generating the mixed phase, which is MgNb₂O_6. Extending annealing time appropriately can improve the dielectric constant and also reduce the dielectric loss of BMN. Particularly, the rate of dielectric tuning can be increased by extending annealing time. The best conditions of the heat treatment process is that the heat treatment temperature is 750 ^oC and the annealing time is 45 min. The thin film’s dielectric tunable rate is 27% and the dielectric loss was 0.0043 under 1.18 MV/cm at the moment.

Keywords：BMN thin films，Magnetron sputtering，heat treatment，dielectric properties，leakage current density

目 录

摘要 I

Abstract II

第一章 绪论 1

1.1 介电薄膜的研究背景及意义 1

1.1.1介电薄膜的发现与发展 1

1.1.2介电薄膜的介电性能 1

1.2 BMN薄膜的研究现状 2

1.2.1 BMN薄膜的发现与发展 2

1.2.2 Bi_1.5Mg_1.0Nb_1.5O₇结构及其特点 3

1.3 薄膜的制备方法 5

1.4 本文研究内容 6

第二章 研究方法与实验 7

2.1 BMN陶瓷靶材的制备 7

2.2 BMN薄膜制备工艺 9

2.2.1 衬底的选择与预处理 9

2.2.2 磁控溅射制备薄膜 9

2.2.1 BMN薄膜的热处理 10

2.3 电容结构的BMN薄膜制备 11

2.4薄膜的表征 12

第三章 实验结果与讨论 13

3.1 退火热处理温度对BMN薄膜晶体的影响 13

3.2 退火热处理时间对BMN薄膜晶体和介电性能的影响 15

3.2.1 退火时间对BMN薄膜相结构的影响 15

3.2.2 退火时间对BMN薄膜介电性能的影响 17

第四章 结论 22

参考文献 23

致谢 26

第一章 绪论

1.1 介电薄膜的研究背景及意义

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