Ta基纳米薄膜扩散阻挡特性的比较研究

采用直流磁控溅射方法在p型(100)Si衬底上制备了Cu/Ta、Cu/Ta-N和Cu/Ta-Al-N复合膜,并对薄膜样品进行了卤钨灯快速热退火.用四探针电阻测试仪(FPP)、AFM、SEM、Alpha-step IQ台阶仪和XRD等分析测试方法对样品的形貌结构与特性进行了分析表征,并对N和Al的掺杂机理进行了讨论.实验结果表明,Ta、Ta-N和Ta-Al-N膜层的Cu扩散阻挡特性逐渐增强,Ta/Si界面上的反应和Cu通过多晶Ta膜扩散到Si底并形成Cu3Si共同导致了Ta阻挡层的失效,而Cu通过Ta-N和Ta-Al-N结晶后产生的晶界扩散到Si底并形成Cu3Si是两者失效的唯一机制.N的掺入促进了非晶薄膜的形成且有利于消除界面反应,而Al的掺入将进一步提高薄膜的结晶温度和热稳定性.

Comparison of diffusion barrier properties of nanoscale Ta-based thin-films

Cu/Ta,Cu/Ta-N and Cu/Ta-Al-N multilayer structures were deposited on p-type Si(100)substrates by DC magnetron sputtering,then rapid thermally annealed by tungsten halide lamp.The surface morphology and properties of the thin-films were investigated by four-point probe(FPP)sheet resistance measurement, AFM,SEM,Alpha-step IQ profilers and XRD,also the effects of N and AI doping on diffusion barrier property were discussed.The experimental results show that the barrier properties against Cu diffusion are gradually en- hanced from Ta,Ta-N to Ta-Al-N.The interface reaction of Ta/Si together with Cu_3Si,which resulted from Cu diffusion along the grain boundaries towards Si,make Ta barrier failed,while the failure of Ta-N and Ta-Al- N are both onty attributed to the formation of Cu_3Si on barrier/Si interface which is due to Cu diffusion along the grain boundaries of crystallized barrier films.N doping favors the formation of amorphous thin-film and e- liminates the interface reaction,while Al doping increases crystallization temperature and enhances thermo- chemical stability of thin-film.