摘要
本論文研究主要可分成三部分，第一部分研究利用化學氣相沉積所製備的四種不同 low-k 薄膜，k 值約為 2.5~3.6，並分析薄膜的物理、電特性以及可靠性。除氟化矽酸鹽玻璃 (FSG) 和有機矽玻璃 (OSG) 薄膜外，還比較使用兩種不同的有機致孔劑，並將其沉積於OSG薄膜上，形成多孔隙 Porous low-k (P-OSG) 薄膜，而有機致孔劑分別為高分子碳氫化合物 (ATRP) 和環辛烷 (C8H16)。由實驗結果得知，雖然 P-OSG 薄膜相較於 FSG 及 OSG 薄膜有更低的 k 值，但其電性和可靠性卻較差。因此，在先進的節點技術中使用較低 k 值的 Porous low-k 薄膜仍然是值得商榷的。而進一步對 P-OSG 薄膜的實驗結果探討，發現使用 ATRP 前體致孔劑相較於使用 C8H16 前體致孔劑的 P-OSG 薄膜，其薄膜擁有更好的機械應力、電性和可靠度。由實驗結果得知，前體致孔劑會影響 P-OSG 薄膜的性質；因此，在 BEOL 互連中必須採用 Porous low-k 薄膜時，則可以透過選擇前體致孔劑來沉積 P-OSG 薄膜。 第二部分則探討 SiCNH 阻障層對 low-k低介電材料電性及可靠度之影響，使用的 low-k 低介電材料為 SiCOH，有兩種形式:分別為孔隙率為 15 的多孔隙低介電材料 (Porous low-k) 與無孔隙低介電材料 (Dense low-k)。由實驗結果得知，當 SiCNH 阻障層堆疊後，Dense 和 Porous low-k 薄膜其介電常數皆會增加，而 Porous low-k 薄膜其增加量相對較高；且 SiCNH 阻障層堆疊後，能使Dense 和 Porous low-k 薄膜較能阻擋銅離子擴散及減少氧氣電漿損傷，且能改善 Porous low-k 薄膜的電性及可靠度。 在銅金屬的 BEOL 互聯當中，若必須使用 Porous low-k 薄膜，則需要一層介電阻障層堆疊，然而介電阻障層的堆疊會使介電常數增加；因此，第三部分為無阻障層氟化矽玻璃 (FSG) 薄膜的製成評估，並與 SiCNH 阻障層/Porous low-k (p-SiCOH/SiCNH) 堆疊薄膜一同比較。雖然 FSG 薄膜相較於 p-SiCOH/SiCNH 疊層薄膜有更高的電容，但是 FSG 薄膜卻有更高的硬度、崩潰電場、阻擋銅離子擴散及減少氧氣電漿損傷的能力。因此了解到，若在較低的 BEOL 製程中，使用無阻障層的 FSG 薄膜是可行的。
並列摘要
This thesis consists of three parts. The first part focuses on the physical and electrical characteristics, as well as the reliability, of various commercial low-k dielectric films with k values from 2.50 to 3.60, deposited by plasma-enhanced chemical vapor deposition were investigated. In addition to fluorinated silicate glass (FSG) and dense organosilicate glass (OSG) low-k dielectric films, two porous OSG (P-OSG) films deposited using different sacrificial organic porogen precursors (alpha-terpinene (ATRP) and cyclooctane (C8H16)) were compared. The P-OSG films provide a lower k value than other low-k dielectric films, however, their resistance to the integration process is relatively low, resulting in a large increase in the k value and degraded electrical performance and reliability. In this study, the P-OSG film for the ATRP precursor exhibited better mechanical, electrical, and reliability characteristics than that for the C8H16 precursor. Accordingly, the pursuit of the highly porous low-k dielectric films with a further low k value for the advanced technology nodes remains arguable. If a highly porous low-k dielectric film must be adopted in BEOL interconnects, the use of a sacrificial porogen precursor must be carefully considered because it would affect the properties of the resulting P-OSG films. Next, electrical characteristics and reliability of the dielectric stack with a low-k SiCOH film and a capping SiCNH film. Two kinds of low-k SiCOH films were used the dense low-k dielectric film without porosity and the porous low-k film with a porosity of 15. The deposition of the capping SiCNH layer on both dense and porous low-k SiCOH films increased the overall dielectric constant. A higher increase in the dielectric constant was detected for the porous low-k SiCOH film. By capping the SiCNH layer on the low-k SiCOH films, the phenomena of O2 plasma damage and Cu ions diffusion can be retarded. Moreover, lager improvements on time-dependent-dielectric- breakdown and electromigration lifetimes were detected on the porous low-k SiCOH film. A dielectric barrier is required for the porous low-k dielectric film used in Cu interconnects, resulting in an increased effective dielectric constant. Next, a barrier-free process for FSG dielectric film is evaluated. FSG dielectric films had a higher capacitance than p-SiCOH/SiCNH stacked films, although, they can provide a higher hardness, O2 plasma resistance, Cu barrier, and dielectric breakdown strength. Therefore, a barrier-free process for FSG dielectric film is promising and feasible for BEOL integrity.