Ti-Si-N as a diffusion barrier between copper and silicon

초록

Amorphous Ti-Si-N films of approximately 650Å thickness were reactively sputtered on Si wafers using a dc magnetron sputtering system at various N2/Ar flow ratios, and their barrier properties between Cu (750Å) and Si were investigated by using sheet resistance measurements, XRD, SEM, RBS, and AES depth profiles focussing the effect of the niterogen content in Ti-Si-N thin film on the Ti-Si-N barrier properties. As the nitogen content increase, first the failure temperature tends to increase up to 46% and then decrease reversely. Barrier failure seems to occur by the diffusion of Cu into the Si substrate to form Cu3Si, since no other X-ray diffraction intensity peaks (titanium silicides) than Cu and Cu3Si peaks appear up to 800℃. The optimal composition of Ti-Si-N in this study is Ti29Si25N46, and Ti29Si25N46 barrier layer is good enough to prebent the diffusion of Cu into the Si substrate at least up to 650℃