摘要
本文通过使用烧结NdFeB靶材以及利用磁控溅射（直流）法首先摸索了溅射参数对薄膜性能的研究，然后确定最佳参数组合，最后制备了添加Mo，Sm元素后的NdFeB稀土永磁薄膜。利用实验室现有的表征设备如扫描电镜（SEM）,原子力显微镜（AFM），X射线衍射仪（XRD）和振动样品磁强计（VSM）对薄膜表面形貌，微观结构，厚度，物相和磁性能进行全面的分析和测试。
工艺参数对制备单层NdFeB薄膜有较大影响，其中薄膜的沉积速率与溅射功率和溅射时间呈正比关系，沉积速率随着溅射气压的升高而升高，并且在溅射气压为0.8pa的时候沉积速率有最大值，当溅射气压再次升高的时候，沉积速率反而出现了下降的趋势，分析原因是腔室内气体浓度增加过多，导致被电离的Ar+增多，靶材表面溅射出来的原子碰撞几率增多，溅射到基片上原子相对减少，薄膜厚度降低。后期热处理NdFeB薄膜由非晶状态转变成晶态，相邻间的晶粒经过吞噬，重新组合，团簇效应消失，晶粒长大，并且呈岛状结构，生成Nd_2Fe_14B硬磁主相。
在衬底上添加一层Mo后，在形貌方面，NdFeB薄膜表面晶粒分布比较均匀，尺寸比统一，致密性较好；在物相方面，Mo沉积到一定厚度时有助于Nd_2Fe_14B在Mo(110)晶向上生长，有利于NdFeB晶粒择优生长；在磁性能方面，随着Mo层厚度的增加，Mo层形核生成比较均匀致密的膜层，促进了Nd_2Fe_14硬磁主相择优生长，NdFeB薄膜的矫顽力呈现逐渐增加的趋势。
在NdFeB薄膜内混合Sm后，在形貌方面，通过SEM发现经过热处理后NdFeB薄膜横截面内有明显的柱状晶，Sm的加入能使薄膜生长方式为垂直于基片的柱状方向生长；在物相方面，添加微量的Sm能够使NdFeB薄膜的衍射峰强度增加，不同方向上的衍射峰增多，其量过多会起到抑制作用；在磁性能方面，随着Sm含量的增多，形成Nd_2Fe_14B硬磁主相的Fe的含量一直下降，使得磁性能有所下降，但是微量的Sm却能改善薄膜的微观结构，磁晶各向异性增强。
In this paper，the NdFeB target was fabricated by sintered method and wecan use magnetron sputtering (DC) method to study the sputtering parameters onthe performance of the thin films firstly,and then determine the optimalcombination of parameters,and finally prepare the NdFeB rare earth magneticfilms with the elements of Mo,Sm.Using the existing laboratory characterizationequipment such as scanning electron microscopy(SEM), atomic forcemicroscopy(AFM), X-ray diffraction and vibrating sample magnetometer (VSM)to analysize and test the surface morphology, microstructure, thickness, phaseand magnetic properties.
The process parameters have a greater impact on the preparation ofsingle-layer NdFeB films, in which thin film deposition rate and sputteringpower and sputtering time was the direct proportional relationship. Thedeposition rate is increasing with sputtering pressure increased, and thedeposition rate is maximum under0.8pa sputtering pressure,comparing with adownward trend when the sputtering pressure increased again. The analyzedreasons is chamber gas concentrations increasing too much, resultinginionization of Ar+increased, and the target surface sputtered atom collisionprobability increased, and sputtering to the substrate atoms relative reduction infilm thickness decreases. NdFeB films from the amorphous state into thecrystalline state by post-heat treatment, the adjacent grain after phagocytosis,regrouped, cluster effect is gone, grain growth, and was the island structure togenerate the main phase of Nd_2Fe_14B magnetical hard phase.
Adding a layer of Mo on the substrate, the film grain distribution is moreuniform and the size is more conforming, dense well in the morphology ofNdFeB thin film surface; a certain thickness of depositing Mo helpsNd_2Fe_14Bupward growth in Mo (110) and NdFeB grains preferred growth in thephase; with the increase of the Mo layer thickness, Mo layer was formingmore uniform and dense film with generating nucleation, promoting Nd_2Fe_14Bhard magnetic main phase of preferential growth and the coercivity of NdFeBfilms showing a growing trend in magnetic properties.
After NdFeB films mixed Sm, NdFeB films cross-section was observed thecolumnar grain after heat treatment by SEM and added Sm change thin-filmgrowth into the columnar direction perpendicular to the substrate in themorphology; adding a small amount of Sm enable increase diffraction intensityand the number of diffraction peak of the NdFeB films in different direction,which excessive Sm played an inhibitory effect in the phase aspect; with theincrease of Sm content, the formation of Nd_2Fe_14B hard magnetic main phase ofthe Fe content has been declining, making the magnetic properties decline, butthe small amount of Sm was able to improve the film microstructure andenhance magnetic anisotropy in magnetic properties aspect.
引文
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