次22奈米製程之金屬導線技術開發

Silver Metallization for Sub-22nm Technology Node Application

10.29688/MHJ.201202.0001

陳炳茂(Bing-Mau Chen)；蘇盈豪(Yin-Hao Su)；鍾朝安(Chao-An Jong)

金屬導線製程技術 ； 電鍍銀 ； 氮化鈦 ； 表面改質 ； 潤濕性 ； 接面電阻 ； 高溫穩定性 ； Silver Metallization ； Electroplating ； surface modification ； contact resistance ； thermal stability

明新學報

38卷1期（2012 / 02 / 01）

1 - 9

繁體中文

本研究，透過不同處理方式改變氮化鈦（TiN）薄膜之表面潤濕性，探討金屬銀電鍍在以原子層沉積（Atomic Layer Deposition, ALD）製備之氮化鈦薄膜上的還原行為，進而研究其高溫電性、熱穩定性與顯微結構之關係。利用不同氣體電漿作表面轟擊與DHF（Diluted Hydrofluoric Acid）的表面改質方式，不僅提供多餘銀原子還原成核（Nucleation）位址，且提供自由電子供銀原子還原析出，因此不須晶種層（Seed Layer）就可以讓銀金屬直接電鍍在氮化欽薄膜上，且經過600℃真空退火（Annealing）處理，沒有發現任何球化現象與微孔洞產生；透過電子顯微鏡（Scanning Electron Microscope，SEM）結構分析發現，初鍍膜晶界處的空孔存在與否，對高溫晶粒成長後的薄膜穩定性扮演相當重要的角色。另外，利用半導體製程製作量測元件，探討銀與其下氮化鈦之接面電阻特性，其電阻特性經修正後以特徵接面電阻（Specific Contact Resistance）來表示，經過退火與表面電漿清潔過之接面，其特徵接觸電阻可較未處理的試片從10^（-3）Ωcm^2降至10^（-6）Ωcm^2改善有三個數量級之多。本研究開發的銀導線製程組合，在許多方面滿足後段製程技術的測試條件，開發以ALD氮化鈦作為銀之阻障層，兼具晶種與擴散阻障的特性且具有高均覆性與非晶特點，除了免去未來因電鍍失敗而重製成本，厚度降至2nm之後，將可符合2018年國際半導體技術藍圖（International Technology Roadmap for Semiconductors，ITRS）對未來導線之規格，相當具有應用價值。

In this research, the surface modifications of ALD-TiN thin film for Ag electro-plating were investigated. The comparisons among these methods were examined in contact angle, electrical resistance and thermal stability. Combination with chemical and plasma surface treatments, Ag film could be directly plated on more nucleation addresses TiN nucleus without seed layer and no agglomeration and micro voids were observed even after 600℃ annealing. It was found by scanning electron microscope (SEM) characterization shows that the voids in as-deposited Ag film were affective to thermal stability, and stable resistance after thermal annealing was examined. The contact resistance between Ag and TiN film was clearly improved from the order of 10^(-3) to 10^(-6) Ωcm^2 after thermal annealing and plasma cleaning. It fulfills the requirement of interconnect for sub-22nm technology node application.

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