Ta-Si-C 非晶質擴散阻障應用於
銅製程之特性研究

在超大型積體電路連導線製程應用，銅具備低電阻與較佳之抗電致遷移能力，故以銅做為金屬連接導線是必然的趨勢。但為解決銅與矽基材間相互擴散的問題必須在銅與矽間沉積上具有低電阻係數、高熱穩定性及良好界面附著性的擴散阻障層以防止銅與矽反應。 Ta-Si-N 熱穩定性可達900oC/ 1hr，但其電阻率達800μΩ-cm，且由於使用反應性氣體，故製程再現性欠佳。故本研究以直流磁控濺鍍法製備Ta-Si-C 使用C 取代N 增加製程穩定性並期以應用於銅連線的阻礙層。Ta-Si-C 薄膜使用不同氣體進行電漿改質，探討Ta-Si-C 薄膜的相變化及熱穩定性。之後將薄膜進行熱處理，並藉由四點探針(FPP)、X 光繞射分析儀(XRD)、穿透式電子顯微鏡(TEM)分析薄膜特性。本研究並探討如何減少Ta-Si-C薄膜應用於銅製程中擴散阻礙層所造成 Ta-Si-C(O)x氧化層，並分別進行Ar+H2及Ar+N2兩種氣體的電漿表面改質 Ta-Si-C薄膜，接著製備Cu/Ta-Si-C/Si結構。結果顯示以Ar+H2及Ar+N2兩種氣體的電漿改質Ta-Si-C薄膜相對於未經電漿改質Ta-Si-C薄膜有較佳的效果。由結構分析顯示使用Ar+N2及Ar+H2 兩種氣體的電漿改質Ta-Si-C薄膜初鍍膜初為非晶質，薄膜的電阻率分別為 400μΩ-cm、372μΩ-cm與361μΩ-cm。隨著熱處理溫度的增加，Ar+N2與Ar+H2 電漿表面改質薄膜在700oC時TaSi2有微晶的現象產生，而使用Ar+N2電漿表面改質薄膜則在750oC才有結晶的現象產生。使用Ar+H2電漿表面改質可有效使薄膜變得更緻密並降低電阻率；結果顯示Ta-Si-C合金薄膜經Ar+N2氣氛下表面改質可改善Ta-Si-C薄膜的熱穩定性，並將此製程應用於銅製程作為擴散阻礙層， Cu/Ta-Si-C(5nm)/Si結構使用Ar+H2進行電漿表面改質薄膜的熱穩定性到達750℃/1 min，Cu/Ta-Si-C(5 nm)/Si結構使用Ar+N2進行電漿表面改質薄膜的熱穩定性到達800℃/1 min，結果顯示使用Ar+N2進行電漿表面改質可提升薄膜的熱穩定性。

關鍵字

Ta-Si-C 薄膜；電漿表面改質； Ta-Si-C(O)x ；熱穩定性

並列摘要

Copper is to be used in deep submicron ultra-large scale integration (ULSI) metallization due to its lower resistivity and better electromigration resistance. Since Cu diffuses repidly in Si, and therefore introduces deep-level traps, a proper diffusion barrier is needed. The barrier should have low resistivity, high thermal stability, and good adhesion with Cu and the substrate. Ta-Si-N thin films failure temperature of 800 oC/1 hr, and the electrical resistivity was 800 μΩ-cm, but it has bad reproducibility.We expect C to replace N then add stability of process.This study prepared Ta-Si-C thin films using DC magnetron co-sputtering for copper metallization, subsequently followed by plasma surface treatment in Ar+H2 and Ar+N2 to evaluatie the phase transition and thermal stability of the annealed. Thin film properties and failure behavior of the studied films were elucidated by using four-point probe (FPP), X-ray diffraction (XRD), transmission electron microscopy (TEM). To reduce the thickness of Ta-Si-C(O)x , plasma treatmen on Ta-Si-C thin films by Ar+H2 and Ar+N2 , and prepare Cu/Ta-Si-C/Si structure, and plasma treatmen on Ta-Si-C thin films by, Ar+H2 and Ar+N2. Without plasma treatment on Ta-Si-C indicated that Ta-Si-C thin films is amorphours, and the electrical resistivity was 400 μΩ-cm, the electrical resistivity was 372 μΩ-cm using Ar+N2 plasma treatment, and the electrical resistivity was 361 μΩ-cm using Ar+H2 plasma treatment. The without plasma treatment or Ar+H2 plasma treatment induced the Ta-Si-C film became micro-crystallization TaSi2 phase when the film was annealed at 700 oC, and Ar+N2 plasma treatment resulted in Ta-Si-C film crystallite into TaSi2 phase when the film was annealed at 750 oC. Ar+H2 plasma treatment is effective in reducing resistivity of thin film, and Ar+N2 plasma treatment is promising in improving thermal stability of thin film. Using Ar+H2 plasma treatment on 5 nm Ta-Si-C film for Cu/Ta-Si-C/Si structure, the stacked film has a failure temperature of 750 oC/1 min, but using Ar+N2 plasma treatment on 5 nm Ta-Si-C film for Cu/Ta-Si-C/Si structure, the stacked film has a failed at 800oC/1 min. The experiment results indicated Ar+N2 plasma treatment is effectively on enhancing thermal stability of Ta-Si-C thin films.

並列關鍵字

Ta-Si-C ； plasma surface treatment ； thermal stability ； Ta-Si-C(O)x

參考文獻

[2] G. E.Moore, “Cramming more components onto integrated

Devicesand Circuits Science”, Technology and Manufacturability

Symposium, 25(1994).

[4] S. P. Murarka, “Multilevel interconnections for ULSI and GSI era,” Mater.

[5] The International Technology Roadmapfor Semiconductors, ITRS, (2003).

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Ta-Si-C 非晶質擴散阻障應用於銅製程之特性研究

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