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研究生: 鄭謀鴻
Mou-Hong Cheng
論文名稱: 新式金屬結構技術開發研究
Novel Metallization Technology development Study
指導教授: 鍾朝安
Jong, Chao-An
李敏鴻
Lee, Min-Hung
學位類別: 碩士
Master
系所名稱: 光電工程研究所
Graduate Institute of Electro-Optical Engineering
論文出版年: 2013
畢業學年度: 101
語文別: 中文
論文頁數: 63
中文關鍵詞: 金屬導線製程技術電鍍銀接面電阻熱穩定性
英文關鍵詞: Metallization technology, Silver electroplating, Contact resistance, Thermal stability
論文種類: 學術論文
相關次數: 點閱:190下載:0
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  • 本研究採用銀金屬做為半導體元件之金屬導線材料,利用原子層沉積技術製備之氮化鈦薄膜,兼具擴散阻障層與電鍍晶種層透過表面氣體電漿轟擊與稀釋氫氟酸浸泡對氮化鈦薄膜進行表面處理,藉由改善氮化鈦表面濕潤性來觀察銀電鍍於其上的變化,並利用高溫退火實驗藉由接面二極體漏電流實驗結果,顯示氮化鈦薄膜可有效阻擋銀離子於高溫400~600 oC的擴散行為。
    本研究透過黃光微影系統製作出350、400以及450 nm線寬的導線模型,使用底部成長的技術,成功地將銀金屬填入導線模型。剛鍍好的銀導線結構比較鬆散、且表面粗糙。相信在退火處理後會比較完整,缺陷也會比較少。
    本研究也利用傳統鑲嵌式製程製作出上開口150 nm、底部寬度84nm的導線模型,成功地將銀金屬填入導線模型中,在沒有使用任何添加劑的情況下,中央縫隙將可能會遺留,所以,我們相信在未來,添加劑的研究將會是實驗銀導線金屬化一個很重要的因素。

    In this study, we investigated the silver metallization technology and feasibility of Ti-based diffusion barrier for Back-Eend-of-Line (BEOL) interconnect application. A single ALD-TiN film with bi-functional diffusion barrier and plating seed layer was developed. By way of the surface modification of TiN film with energetic plasma bombardment and DHF immersion, the wetting behavior for electroplating Ag film was effectively modified. We successfully plating Ag on treated TiN film without any catalyst or seed layer prior to the Ag deposition. Junction leakage current measurement using n+/p-Si diode showed that the titanium nitride can effectively prevent silver diffusion even after 400oC anneal process.
    To integrate the Ag and ALD-TiN barrier process, bottom-up Ag electroplating surrounding by TiN film was proposed. Line width of 350, 400 and 450 nm was formed via Photolithography. Post plating Ag line with distributed grain size was not as smooth as sputtering film. It is believed that the pre-treatment is necessary for better wettability and microstructure.
    Except the bottom-up Ag electroplating, traditional damascene metal plating was checked for electroplating condition tuning. A tapered plug with 150nm top-opening and 84nm bottom width was prepared for Ag gap-filling. We found that the seam or central void will be left without any additive added in the electrolyte. That is, the study of additive in the future will be an important issue in realizing Ag metallization.

    摘要 I Abstract III 致謝 V 目錄 VI 圖目錄 IX 表目錄 XII 第一章緒論 1-1.研究動機 1 1-2.研究目的 5 第二章文獻回顧 2-1.導線尺寸效應(Size effect) 7 2-2.銅製程 10 2-3.擴散阻障層的選擇 12 2-3-1.氮化鈦之性質與結構 15 2-3-2.原子層沉積(Atomic Layer Deposition, ALD) 16 2-4.銀導線特性 17 2-5.電致遷移(Electromigration, EM) 20 第三章實驗方法與步驟 3-1.實驗藥品 23 3-2.實驗儀器設備 23 3-2-1.電化學沉積系統 23 3-2-2.原子層化學氣象沉積(Atomic Layer Chemical Vapor Deposition, ALD) 24 3-2-3.後段真空退火爐管( Backend vacuum annealing furnace ) 26 3-2-4.金屬四點探針量測儀(Metal 4 point probe) 27 3-2-5.電性量測系統 29 3-2-6.微影系統 30 3-3.材料分析設備 32 3-3-1.掃描式電子顯微鏡( Scanning Electron Microscope, SEM ) 32 3-3-2透式電子顯微鏡( Transmission Electron Microscope, TEM ) 33 3-4.實驗流程 34 3-5.實驗步驟 35 3-5-1.基板清洗與製備 35 3-5-2.銀電鍍液配置與導線製作 35 3-5-3.熱退火處理 36 3-5-4.金屬薄膜四點探針量測 36 3-5-5.掃描式電子顯微鏡觀察 37 3-5-6.接面漏電流量測 37 3-5-7.導線模型製作 39 3-5-8.擴散阻障層蝕刻 39 第四章結果與討論 4-1.銀金屬薄膜表面分析 40 4-2.氮化鈦對銀金屬接面漏電流測試 41 4-3.導線模型製作與底部成長技術填充測試 46 4-3-1.I-Line光學步進機微影與填充結果 46 4-3-2.ELS7500電子束直寫系統微影與填充結果 49 4-4.擴散阻障層蝕刻 51 4-5.鑲嵌式結構之銀金屬填充測試 53 第五章結論 56 未來展望 57 參考資料 58 圖目錄 圖1-1、不同製程材料對線路訊號延遲比較圖 1 圖1-2、銅製程因尺度微縮阻值上升示意圖 3 圖2-1、銅導線中電阻率與線寬、導線高度之關係圖 7 圖2-2、銅導線中晶粒大小分佈圖 8 圖2-3、銅導線中表面散射與晶界散射示意圖 9 圖2-4、橫截面積比例隨阻障層厚度與線寬之變化圖 10 圖2-5、大馬士革(Damascene)銅導線製程示意圖 11 圖2-6、不同擴散阻障層材料對銀金屬的擴散行為 13 圖2-7、銀金屬於TiN之擴散與自聚現象 14 圖2-8、原子層沉積原理示意圖 15 圖2-9、銅與銀在矽基板之擴散係數比較圖 18 圖2-10、銀與銅電阻率隨膜厚變化之比較圖 19 圖2-11、含氰之銀電鍍液進行導線之填充 19 圖2-12、金屬導線因電致遷移導致空洞(void)或土丘(hillock) 形成圖 21 圖2-13、以EBSD (electron back scattering Diffraction) 觀察 銅導線中竹節狀晶粒形貌圖 22 圖3-1、恆電位電流儀, EG&G Princeton Applied Research, Model 273A 24 圖3-2、原子層化學氣相沉積系統, AIXTRON StrataGem 200 25 圖3-3、後段真空退火爐管系統, 倍強科技 26 圖3-4、四點探針量測示意圖 28 圖3-5、金屬四點探針量測儀,Four Dimensions Inc. 280P 28 圖3-6、半導體元件特性量測系統,Agilent Technologies B1500A 29 圖3-7、I-Line光學步進機, Canon FPA 3000 i5+ I-line stepper       30 圖3-8、ELS7500電子束直寫系統, ELIONIX ELS7500-EX 31 圖3-9、掃描式電子顯微鏡, JEOL JSM 6500-F 32 圖3-10、穿透式電子顯微鏡, JEOL JEM-2010F 33 圖3-11、實驗流程圖 34 圖3-12、量測銀導線漏電結構示意圖 38 圖3-13、擴散阻障層蝕刻示意圖 39 圖4-1、電鍍銀薄膜於氧化鈦薄膜上之表面形貌 40 圖4-2、不同溫度退火對銀與銅擴散造成在N+P-Si二極體上 的漏電行為與氮化鈦厚度的比較 44 圖4-3、3 nm氮化鈦經由不同電漿處理時間與退火對銀與銅 擴散造成在N+P-Si二極體上的漏電行為與氮化鈦厚 度的比較 44 圖4-4、不同氮電漿處理時間之TEM剖面圖 45 圖4-5、I-line光學步進機微影之不同線寬導線模型 47 圖4-6、電鍍銀的導線模型填充-I-line 48 圖4-7、電鍍銀的導線模型填充-ELS7500 50 圖4-8、擴散阻障層蝕刻 52 圖4-9、鑲嵌式結構之銀金屬填充 54 圖4-10、鑲嵌式結構回填後之銀金屬填充 55 表目錄 表1-1、元件微縮所遇之挑戰縮所遇之挑戰 6 表2-1、氮化鈦之物理性質 16 表2-2、鋁、銅、銀金屬之特性比較 20 表3-1、銀電鍍液組成 36

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