Ta-based障礙層在Cu/PAE-2(low k)/Si 之熱穩定性研究

Abstract

本論文主要研究低介電常數材料PAE-2 之熱穩定性與電特性。吾人利用橢圓測厚儀得知PAE-2薄膜的介電長數值約為2.9，PAE-2薄膜的熱穩定性可達450℃左右。在與銅金屬的整合方面，吾人研究Cu/PAE-2/Si 系統的熱穩定性可達200℃，另外也對鉭(Ta)及氮化鉭(TaN)等擴散障礙層應用於Cu/Ta/PAE-2/Si 與Cu/TaN/PAE-2/Si 結構的熱穩定性加以探討。研究結果發現Ta及TaN擴散障礙層可分別提高Cu/barrier/PAE-2/Si結構之熱穩定性200及250℃。再者，吾人使用電容-電壓與加溫偏壓法來研究Al/PAE-2/SiO2/Si與Cu/PAE-2/SiO2/Si結構之熱穩定性，發現在PAE-2薄膜內含有可移動的正負離子。在材料分析方面，吾人利用掃描式電子顯微鏡、二次離子質譜儀、X光繞射分析、與TDS分析來探討PAE-2的劣化原因。

This thesis investigates the thermal stability and electrical properties of the low-k dielectric material of PAE-2 film. The dielectric constant of the PAE-2 film was determined to be 2.9 and the PAE-2 film was thermally stable up to 450oC. The thermal stability of the Cu/PAE-2/Si system is up to 200oC and the effects of Ta and TaN diffusion barrier sandwiched between Cu and PAE-2 layer were investigated using the technique of I-V measurement. It is found that the use of Ta and TaN barriers raised the thermal stability temperature of the system by 200 and 250oC, respectively. Thermal stability of the Cu/PAE-2/SiO2/Si structure was also investigated using the technique of C-V measurement and the bias temperature stress (BTS). It is found that large amount of positive and negative mobile ions were presented in the PAE-2 layer, causing large voltage shift of the C-V curve after BTS stress. Material analyses of SEM, SIMS, XRD, and TDS measurement were used to investigate the degradation mechanism of these MIS capacitors.