Developments of new complex materials using mime and interface diffusion of the supersaturated alloy elements in thin films

高温退火后，在Cu（Ti）薄膜与SiO_2/Si衬底的界面处形成了薄的富Ti扩散阻挡层。这种技术被称为“自形成的扩散屏障”，这是有吸引力的超大规模集成电路（ULSI）互连的制造。此外，我们研究了这种技术的适用性Cu（Ti）合金薄膜上沉积的四个低介电常数（低k）的介质层，这是潜在的未来ULSI-Si器件的介质层。利用透射电子显微镜（TEM）和二次离子质谱（西姆斯）对薄膜的微观结构进行了分析，并与薄膜的电学性能进行了关联。结果表明，在Cu（Ti）/介质层样品中均形成了富Ti界面层。控制自生富钛界面层成分的主要因素是介质层中的C浓度，而不是Ti化合物（TiC和TiSi）的形成焓。晶体TiC形成在具有高于17原子%的C浓度的介电层上。

Thin Ti-rich diffusion barrier layers were found to be formed at the interface between Cu(Ti) films and SiO_2/Si substrates after annealing at elevated temperatures. This technique was called "self-formation of the diffusion barrier," which is attractive for fabrication of ultra-large scale integrated (ULSI) interconnects. Furthermore, we investigated the applicability of this technique to Cu(Ti) alloy films which were deposited on the four low dielectric constant (low-k) dielectric layers which are potential dielectric layers of future ULSI-Si devices. The microstructures were analyzed by transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS), and correlated with the electrical properties of the Cu(Ti) films. It was concluded that the Ti-rich interface layers were formed in all the Cu(Ti)/dielectric-layer samples. The primary factor to control composition of the self-formed Ti-rich interface layers was the C concentration in the dielectric layers rather than the formation enthalpy of the Ti compounds (TiC and TiSi). Crystalline TiC was formed on the dielectric layers with a C concentration higher than 17 at.%.