阻障層對多孔低介電材料電性與可靠度之影響

本研究探討半導體後段製程中的銅阻障層與多孔性低介電係數 (low-k) 絕緣層中整合後，對其電性及可靠度等特性之影響。本研究主要可以分成三個部分: 第一部分；主要比較兩種不同種類的 SiCxNy 介電阻障層，沉積在多孔碳氫氧化矽 (p-SiOCH) low-k 材料表面，所形成的疊層薄膜之特性、電性、及可靠度。第一種SiCxNy薄膜為使用多源前驅物所沉積 (SiCxNy-1) ；第二種則為使用單源前驅物所沉積 (SiCxNy-2) 。實驗結果指出 SiCxNy-2 有較好的可靠度與銅阻障之能力這是因為 SiCxNy-2 的沉積過程對 low-k 絕緣層的影響不大；而對於 SiCxNy-1 薄膜，在沉積的過程會對 low-k 絕緣層產生嚴重的電漿損傷，造成可靠度與銅阻障能力下降 [1]。第二部分；則將第一部分得到的樣本施以紫外光照射後，分析對其疊層薄膜之特性、電性、及可靠度之影響；由結果可發現兩種樣本經紫外光照射後，電性與可靠度皆有所改善，對於 SiCxNy-2 疊層薄膜，可靠度改善較多，對於 SiCxNy-1 疊層薄膜，電性改善較多；然而，介電係數與平帶電壓遲滯均增大；在正電應力與熱應力作用下， SiCxNy-1 與 SiCxNy-2 疊層薄膜阻擋銅擴散的能力，均產生退化的現象；對於 SiCxNy-2 疊層薄膜，在正電應力下退化較多；而在熱應力下， SiCxNy-1 疊層薄膜則有較大的退化。第三部分；主要研究錳作為金屬阻障層與添加氮元素對於其可靠度的影響；在氧化錳濺鍍前將氮氣滲入多孔 low-k 絕緣層的孔隙之中，在氧化錳濺鍍後進行 450 ℃ 的熱退火，使多孔 low-k 絕緣層中的氮氣與氧化錳金屬阻障層進行熱化學反應得到氮氧化錳金屬阻障層；雖然氮氧化錳的電性和氧化錳相比較差；但是經由可靠度測量發現在低電場的狀態下氮氧化錳阻障層的可靠度優於氧化錳阻障層 [2]。

關鍵字

low-k 材料；介電層；碳氮化合物；阻障層；前驅物；紫外光；滲氮處理；濺鍍錳；可靠度；崩潰

並列摘要

This thesis investigates the effects of barrier larer on the electrical characteristics and reliability of low-dielectric-constant (low-k) dielectric materials. There are three parts in this thesis, described as follows: The first part compares two types of Silicon carbonitride (SiCxNy) layers using different deposition precursors (single-source and multi-source precursors), which were capped onto the porous low-k SiOCH films. The electrical characteristics and reliability of the fabricated SiCxNy/SiOCH dielectric stacks were compared. Less plasma damage on the low-k SiOCH film was made for capping SiCxNy layer using single-source precursor as compared to that using the conventional multi-source precursors, thereby achieving a lower capacitance. Additionally, time-dependence-dielectric-breakdown reliability of the SiCxNy/SiOCH dielectric stack was promoted by adopting SiCxNy layer deposited using single-source precursor. Moreover, its barrier against Cu penetration under an electrical stress or thermal stress kept comparable capacity without degradation. Therefore, the developed SiCxNy layer deposited using single-source precursor in this study provides a promising integrity with a porous low-k dielectric in advanced technological nodes for semiconductor industry. The second part is to study the effect of ultraviolet (UV)-assisted thermal curing on the electrical properties and reliability of SiCN/SiCOH stacked dielectrics. After UV-assisted thermal curing, the electrical properties and reliability of both SiCxNy/SiOCH dielectric stacks were improved. The SiCxNy layer deposited using single-source precursor achieved the best reliability improvement, but SiCxNy layer deposited using multi-source precursor had lager improvement on the electrical properties. However, UV-assisted thermal curing induced the increase in the capacitance and flatband voltage hysteresis. Additionally, under positive electrical stress and thermal stress, the ability to against Cu penetration were weakened. A novel barrier processing on a porous low-k film was developed in the third part: an ultrathin Mn oxide on a nitrogen-stuffed porous carbon-doped organosilica film (p-SiOCH(N)) as a barrier of the Cu film was fabricated. To form a better barrier Mn2O3-xN film, an additional annealing at 450 °C was implemented. In this study, the electrical characteristics and reliability of this integrated Cu/Mn2O3-xN/p-SiOCH(N)/Si structure is investigated. The proposed Cu/Mn2O3-xN/p-SiOCH(N)/Si capacitors exhibited poor dielectric breakdown characteristics in the as-fabricted stage, although, less degradation was found after thermal stress. Moreover, its time-dependence-dielectric-breakdown electric-field acceleration factor slightly increased after thermal stress, leading to a larger dielectric lifetime in a low electric-field as compared to other MIS capacitors. Furthermore, its Cu barrier ability under electrical or thermal stress was improved. As a consequent, the proposed Cu/Mn2O3-xN/p-SiOCH(N) scheme is a promising integrity for back-end-of-line interconnects.

並列關鍵字

low-k material ； dielectric ； carbonitride ； barrier ； precursor ； ultraviolet ； nitriding treatment ； sputtering of manganese ； reliability ； breakdown

參考文獻

[1] Y. L. Cheng, and Y. L. Lin, “Comparison of SiCxNy barriers using diﬀerent deposition precursors capped on porous low-dielectric-constant SiOCH dielectric ﬁlm.”, Thin Solid Films, 702, (2020) 137983

Google Scholar

[2] Y. L. Cheng, Y. L. Lin, C. Y. Lee, G. S. Chen, and J. S. Fang, “Electrical Characteristics and Reliability of Nitrogen-Stuﬀed Porous Low-k SiOCH/Mn2O3-x/Cu Integration.”, Molecules, 24(21), (2019) 3882.