Abstract
鉭化物金屬薄膜鍍製在鋁矽間, 顯現出高溫穩定之特質, 可被應用作為鋁矽接觸系統的擴散障礙層. 本研究比較鉭矽化物以及鉭矽氮化物在鋁矽間作為擴散障礙層的效果. 研究方法特別強調電性量測, 包含漏電流以及接觸阻抗的測量. 結果發現鉭矽氮化物是比較好的擴散障礙層,當燒結溫度高至 530度時, 鋁/ 鉭矽氮化物/ 矽系統仍能保持接觸完整性. 雖然如此, 鉭矽氮化物的電阻係數以及鋁/ 鉭矽氮化物/ 矽系統的接觸阻抗值偏高, 這代表將氮加入鉭矽化物中不僅會影響其作為擴散障礙層的效果, 而且會影響其在金屬接觸中的電性結果. 在本論文中, 鉭矽 (氮)化物的結構以 X光繞射(XRD),穿透式電子繞射(TED),穿透式電子顯微鏡(TEM), X光電子儀(XPS),歐傑電子能譜 (AES),及van der Pauw量測法來鑑定. 藉此得知在鉭矽氮化物膜中除了有二矽化鉭及三矽化五鉭晶粒之外, 還有氮化鉭與氮化矽等化合物存在. 我們認為這是鉭矽氮化物在鋁矽間有較好擴散障礙效果的原因. 最後, 我們製作鋁/鉭矽氮化物/ 鉭矽化物/ 矽金屬接觸系統. 正如預料, 此系統同時有鉭矽化物作金屬接觸與鉭矽氮化物作擴散障礙層的好處. 此系統的熱穩定溫度可達 530度而且具有低片電阻與低接觸阻抗的特性. 其接觸阻抗值低於 5E-7 ohm- cm2,此值符合超大型積體電路應用的要求.Tantalum-based thin metal films between Al and Si exhibit high-temperature stability. They can be used as the diffusionbarrier in Al/Si contacts. In this work TaSix and TaSixNy filmsas the diffusion barrier between Al and Si substrates have beencompared. Detailed investigations on electrical measurements,including the reverse leakage current density of Al/TaSix/n+pSiand and Al/TaSixNy/n+pSi diodes, and specific contactresistance of Al/TaSix/n+Si and Al/TaSixNy/n+Si, have beenperformed. It was found that the TaSixNy film can act as abetter diffusion barrier than the TaSix film. Based onelectrical data, it is demostrated that the TaSixNy showsdrawbacks of large sheet and contact resistance in contact withAl and n+Si. Therefore the incorporation of N into TaSix wouldinfluence the barrier performance and electricalcharacteristics in contacts. In this work the structure of eachTaSix(Ny) film was investigated by XRD, TED, TEM, XPS, AES, andvan der Pauw methods. Sheet resistance data show theresistivity of TaSixNy is larger than that of TaSix. Moreoverbased on material analyses it is shown that except for TaSi2and Ta5Si3 phase grains in the TaSixNy films there are Ta-N andSi-N compounds existed, which are responsible for XPS siginalsof Ta-N and Si-N bonds. We suggested that the better diffusionresistance of TaSixNy films between Al and Si is attributed tothis structure. Finally a multilayer Al/TaSixNy/TaSix/n+Sicontact system is fabricated. As is expected, it was found thiscontact system shows the advantage of both the TaSix andTaSixNy films. For the Al/TaSixNy/TaSix/n+Si structure, thethermally stable temperature can be raised up to 530 C with lowsheet and specific contact resistance. The specific contactresistance of Al/TaSixNy/TaSix/n+Si contacts is lower than 5E-7ohm-cm2 for sintering temperature lower than 530 C, this valuesatisfies the equirement of VLSI application.