Synthesis of High Performance Thin Film Magnet on Semiconductor Substrate for the Micromagnetic Devices

采用射频溅射和后退火技术，在Si(111)单晶衬底上成功制备了矫顽力约为15kOe的NdFeB稀土磁体薄膜。在半导体衬底上制备薄膜磁体对MEMS器件的实际应用具有很大的优势。我们在衬底和大约2微米厚的Nd-Fe-B层之间插入了MoSi2缓冲层。我们认为，缓冲层有一个辊来抑制热应变。为了防止ND-Fe-B层的氧化，在顶层镀了一层钛。沉积后的薄膜为非晶相。在真空气氛中用红外辐射在650℃退火后，Nd2Fe14B相在薄膜中结晶良好。X射线衍射图为(00l)衍射峰，并观察到较强的(410)峰。磁滞回线在平行和垂直于薄膜平面的磁场中表现为各向同性。这一结果来自于c轴的随机取向。X-射线衍射仪的分析结果与样品的c轴取向不足相吻合。然而，这部电影的强制力支撑了15Koe以上的巨大价值。扫描电子显微镜和MFM观察表明，薄膜实现了直径为200-350 nm的单一磁畴结构。虽然薄膜c轴择优取向的实现仍然是一个需要克服的课题，但薄膜的高矫直力是微电机或微驱动器在MEMS器件中具体应用的良好性能。

We successfully synthesized thin films of Nd-Fe-B rare earth magnets with coercive force of about 15 kOe on Si(111) single crystal substrate by RF sputtering and post annealing technique. Preparation of thin film magnet on semiconductor substrate has great advantage for the practical application of MEMS devices. We inserted the buffer layer of MoSi_2 between the substrate and Nd-Fe-B layer with approximately 2 micron thickness. We consider that the buffer layer has a roll to depress the thermal strain. The Ti top layer was coated for the protect from oxidation of the Nd-Fe-B layer. The as-deposited films shows the amorphous phase. After annealing at 650 degreeC by infrared radiation in vacuum atmosphere, the Nd_2Fe_14B phase was well crystallized in the film. The XRD pattern showed (00l) diffraction and the strong (410) peak was also observed. The magnetic hysteresis showed the isotropic in the magnetic field parallel and perpendicular to the film plane. This result come from the random orientation of c-axis. The XRD analysis is agreement with the insufficient c-axis orientations. However, the coercive force of the film shoed the large value of aboout 15 kOe. The SEM and MFM observation of the film suggested the single magnetic domain structure with 200-350 nm diameter was realized. Although the realization of the c-axis preferential orientation of the film remains a subject matter to overcome, the high coercivity of the film is good property for the concrete application of the micromotor or microactuator in the MEMS devices.