銅奈米雙晶薄膜之氧化特性研究

Oxidation behavior of Copper thin films with nanoscale twins

李碧華(PI-HUA LEE)

指導教授 ： 廖建能

國立清華大學/工學院/材料科學工程學系/碩士(2011年)

https://doi.org/10.6843/NTHU.2011.00315

摘要

銅奈米尺寸雙晶(nanotwin)結構能大幅提升機械強度以及擁有良好的導電性，因此銅奈米雙晶結構被視為未來半導體製程中內連結導線的候選者之一。然而在文獻中有關於銅奈米雙晶導線氧化方面的資訊缺乏，因此本論文致力於研究銅奈米晶的氧化特性，本研究利用即時電性量測銅薄膜試片，並觀察在不同時期銅薄膜的氧化現象，並討論銅氧化的動力學機制。
本研究最主要的目的是，了解銅薄膜中引入奈米雙晶結構對於銅氧化特性的影響。利用電子槍蒸鍍(E-gun)來製備銅薄膜試片，並於200°C氧化氣氛下持溫，並觀察其氧化情形。首先利用不同鍍膜速率以及鍍膜溫度，製備不同密度的銅奈米雙晶薄膜試片，藉由TEM的分析來確認試片結構，發現高鍍膜速率銅膜擁有較高密度的奈米雙晶結構；此外，本實驗也利用AFM觀察不同時期的氧化形貌，觀察到高鍍膜速率銅膜表面粗糙度較小；利用XRD分析試片，結果顯示：四種試片的氧化物都是生成氧化亞銅，並無氧化銅的相生成；利用SEM從微結構的觀點，高鍍膜速率銅膜氧化過後，氧化層所形成的孔洞以及缺陷較少，由於擁有奈米雙晶的銅膜表面較為平整，因此形成氧化物較小分布也較均勻；利用電性量測方法量測試片在不同溫度下持溫，其電阻值變化與溫度、時間之間的關係，研究發現，高鍍膜速率銅膜氧化速率較低，此外，分析其氧化曲線可以得知：在高鍍膜速率中，主要的氧化機制由擴散所控制，由此可以推論引入奈米雙晶結構之後銅膜的氧化機制傾向以擴散控制為主，由此可以推論奈米雙晶結構扮演著降低氧化速率的角色，因此引入奈米雙晶結構的銅膜可以有效降低氧化速率。

關鍵字

銅氧化 ； 奈米雙晶 ； 即時電性量測

並列摘要

Copper with a high density of nanoscale twins has attracted extensive research attention in the last decade due to its excellent mechanical strength and decent electrical conductivity. Nanotwinned Cu is considered as a candidate of interconnect material in nanoelectronic devices. However, the oxidation behavior of nanotwinned Cu has to be evaluated for process integration considerations. In this study, the oxidation kinetics of Cu films was investigated by in-situ resistivity measurement at different temperatures.
In this study, we deposited Cu films on a Si substrate by e-gun evaporation and oxidized Cu films at 200°C in air to observe the oxidation behavior. The different densities of nanotwinned Cu films were deposited by different deposition rate and deposition temperature. Using TEM analysis, the Cu films with high deposition rate had high densities of nanotwinned structure. The observation of oxidation morphology by AFM showed that Cu films with high deposition rate had lower roughness. The XRD analysis revealed that the Cu oxides were found to be Cu2O. Besides, the SEM observation indicated the Cu films with high deposition rate had small and uniformly distributed oxides. The oxidation rate of Cu films was determined by in-situ resistivity measurement at different temperature. It showed that the higher deposition rate had the lower oxidation rate. In addition, when nanotwinned structure was introduced into Cu films, the primary oxidation mechanism would be diffusion control. Therefore, nanotwinned Cu films could reduce oxidation rate effectively.

並列關鍵字

copper oxidation ； nanotwin structure ； in-situ electrical measurement

參考文獻

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