用于Cu互连的Ta/Ti-Al集成薄膜的结构和阻挡性能

Microstructure and barrier performance of Ta/Ti-Al integrated film used as a barrier layer for Cu metallization

应用射频磁控溅射法在(001)Si衬底上制备了Cu(120nm)/Ta(5nm)/Ti-Al(5nm)/Si异质结,借助原子力显微镜(AFM)、X射线衍射(XRD)和四探针测试仪(FPP)等方法研究了Ta(5nm)/Ti-Al(5nm)集成薄膜用作Cu和Si之间阻挡层的结构和性能。研究发现,Cu/Ta/Ti-Al/Si异质结即使经受850℃高温退火后,样品的XRD图中也没有出现杂峰,表明样品各层之间没有发生明显的化学反应。相对于800℃退火的样品,850℃退火样品的表面均方根粗糙度急剧增大,同时方块电阻也增加了一个数量级,表明Ta(5nm)/Ti-Al(5nm)集成薄膜在850℃时,阻挡性能完全失效。由于Ta和Cu之间存在良好粘附性以及Ti-Al强的化学稳定性,Ta(5nm)/Ti-Al(5nm)集成薄膜在800℃以下具有良好的阻挡性能。

Cu（120nm）/Ta（5nm）/Ti-Al（5nm）/Si heterostructures were deposited on（001） Si substrates using radio frequency magnetron sputtering method.Microstructure of the samples and barrier performance of Ta（5nm）/Ti-Al（5nm） integrated film were investigated using atomic force microscopy（AFM）,X-ray diffraction（XRD）,and four probe method.No obvious impurity peaks can be found for the 850℃ annealed sample,indicating no evident reaction or inter diffusion happened at the interfaces of the sample during the high temperature annealing.Compared with 800℃ annealed sample,much rougher surface with sharp increase in root mean square roughness（RMS）,coupled with a sudden increase in sheet resistance,implies Ta（5nm）/Ti-Al（5nm） integrated film cannot be used as a barrier up to annealing temperature of 850℃.Due to the good adhesion between Ta and Cu and good chemical stability of Ti-Al,Ta（5nm）/Ti-Al（5nm） integrated film has very good barrier performance at temperature lower than 800℃.