离子注入合成β-FeSi_2薄膜的显微结构

Microstructure of β-FeSi_2 film synthesized by ion implantation

采用MEVVA源 (MetalVaporVacuumArcIonSource)离子注入合成 β FeSi2 薄膜 ,用常规透射电镜和高分辨电镜研究了不同制备参数下 β FeSi2 薄膜的显微结构变化 .研究结果表明 :调整注入能量和剂量 ,可以得到厚度不同的β FeSi2 表面层和埋入层 .制备过程中生成的α ,β ,γ和CsCl型FeSi2 相的相变顺序为γ FeSi2 →β FeSi2 →α FeSi2 ,CsCl FeSi2 →β FeSi2 →α FeSi2 或 β FeSi2 →α FeSi2 .当注入参数增加到 60kV ,4× 10 1 7ions cm2 ,就会导致非晶的形成 ,非晶在退火后会晶化为 β FeSi2 相 ,相变顺序就变为非晶→β FeSi2 →α FeSi2 .随退火温度逐渐升高硅化物颗粒逐渐长大 ,并向基体内部生长 ,在一定的退火温度下硅化物层会收缩断裂为一个个小岛状 ,使得硅化物 硅界面平整度下降 .另外 ,对于 β FeSi2 Si界面取向关系的研究表明 ,在Si基体上难以形成高质量 β FeSi2 薄膜的原因在于多种非共格取向关系的并存。

Iron silicide films have been synthesized by metal vapor vacuum arc (MEVVA) ion implantation of iron into (111) and (100) oriented silicon wafers. The structure evolution was characterized using transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). The β FeSi 2 films and buried layers with different depth and thickness were obtained by adjusting the implantation energy and dose. The formation of α, β, γ and CsCl FeSi 2 phases have been observed. The phase transition order is γ FeSi 2→β FeSi 2→α FeSi 2,CsCl FeSi 2→β FeSi 2→α FeSi 2 or β FeSi 2→α FeSi 2. An amorphous layer was formed at 60 kV and 4×10 17 ions/cm 2, the phase transition order is amorphous→β FeSi 2→α FeSi 2. The morphology and position of the silicide films change with the annealing temperature. The silicide grains grow with increasing annealing temperature with further increase of temperature, the continuous silicide layers shrink into isolated islands and the interface β FeSi 2/Si becomes rougher. In this paper, the complicated orientation relationships existing between β FeSi 2 and Si were also investigated.