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題 名 | 濺鍍沈積氮化鉭(Ta[feaf]N/TaN)薄膜的特性與對銅的擴散阻礙性能探討=Evaluation of Tantalum Nitride (Ta[feaf]N/TaN) Thin Films as Diffusion Barriers for Copper |
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作 者 | 許振聲; 黃獻慶; 府玠辰; 莊鑫堅; 陳錦山; | 書刊名 | 真空科技 |
卷 期 | 13:4 2000.11[民89.11] |
頁 次 | 頁4-16 |
分類號 | 440.34 |
關鍵詞 | 單層Ta[feaf]N; 單層TaN; 複層Ta[feaf]N/TaN; 阻礙層薄膜; 銅; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究利用直流磁控濺鍍系統,將厚度均為40nm的單層Ta2N、單層TaN及複層Ta2N/TaN(4個週期)薄膜沈積在(100)矽晶基材上,並利用熱活化敗損分析與X光繞射分析(XRD)、四點探針片電阻量測,由Si/阻礙層/Cu之高溫誘發(1)銅波峰衰退過程與(2)整體片電阻變化趨勢所獲知的敗損活化能數據。來評估這三種薄膜對銅之擴散阻礙能力之差異。同時,我們也運用穿透式與掃描式電子顯微術(TEM/SEM)來了解它們的破壞機制。Ta2N薄膜的基地為非晶質結構;TaN薄膜基地主要為3nm晶粒尺寸的微晶結構;Ta2N/TaN複層薄膜包含非晶質Ta2N(a-Ta2N)與微晶TaN次層(Sublayers)的特性與良好的阻成調制。擴散阻礙層的優劣依序為組成調制Ta2N/TaN、均勻單層TaN、均勻單層a-Ta2N。單層Ta2N與單層TaN分別在溫度≧650℃及≧810℃時,具有極低之敗損活化能值(分別為1.5與3 eV)。然而在850℃之高溫時,週期厚度為10nm之Ta2N/TaN複層阻礙層仍擁有極穩定的微晶結構以有效地阻止銅的擴散,故它的敗損活化能最大(15 eV)。在破壞機制方面,單層Ta2N容易發生高溫晶粒成長的現象,轉變為等軸(~40nm)柱狀晶,使上層銅膜沿最單純的晶界快速擴散模式,造成金屬化系統的敗損。然而,退火Ta2N/TaN阻礙層的Ta2N次層會受到高化學穩定性微晶TaN次層之拘限,而維持相當穩定的顯微結構。由於銅必須經由最複雜的擴散機制穿透阻礙層,大幅延遲銅與矽的互相反應,故Ta2N/TaN複層薄膜是最好的擴散阻礙層。 |
英文摘要 | This study examines the effectives of 40-nm-thick amorphous Ta2N, TaN and Ta2N/TaN alternating films as barrier layers between Si and Cu. Their effectiveness is evaluated by failure-rate-processing analysis, together with transmission and scanning electron microscopies (TEM/SEM) , to evaluate the failure behaviors of the Si/barrier/Cu against annealing time. Results obtained from rate-processing analysis as well as x-ray diffractometry (XRD) and sheet resistance measurement indicate that the reliability of the barriers ranges from Ta2N/TaN (4-period), TaN to amorphous Ta2N. For each metallization layer at a given temperature range, the failure rate based on the decay of (1)the copper XRD signals and (2)electrical conduction against inverse temperature can be related to a straight-line Arrhenisu plot having nearly the same magnitude of activation energy (Q). Upon annealing at 600℃, the amorphous Ta2N barrier is transformed into a columnar grained structure with grain sizes approximately the same as the barrier's thickness. As the crystallized Ta2N barrier possesses the highest density of free-short grain boundaries, copper can speedily penertrate the barrier and finally react with Si to form pyramidal Cu3Si precipitates within the volume of the wafer. Therefore, the Ta2N barrier loses its electrical integrity at the earliest stage and yields the smallest Q of only ~1.5 eV (670-750℃). The TaN barrier annealed under 810℃ can still maintain the same nanocrystalline microstructure to effectively block copper and delay the formation of Cu3Si, thus exhibiting a markedly high Q of ~12eV. However, annealing this TaN barrier at temperatures surpassing 810℃ tends to transform its microstructure into 40-nm-sized grains, which also creates free-short routes for Cu diffusion. Therefore, the TaN barrier has a significantly reduced Q of only ~3 eV (810-850℃). As the Ta2N and TaN sublayers contained in the 4-period alternating film can maintain a fine (<3nm) grained structure to pose complex routes against Cu diffusion, the Ta2N/TaN multiple barrier at the highest temperature regime (840-860℃) still has the greatest Q of 15 eV. |
本系統中英文摘要資訊取自各篇刊載內容。