Cu(CoN)與CoN薄膜應用於銅製程之特性研究

Characteristics of Cu(CoN) Film and CoN Film on Copper Interconnection

王梓育(Tzu-Yu Wang)

指導教授 ： 方昭訓

國立虎尾科技大學/工程學院/材料科學與綠色能源工程研究所/碩士(2010年)

https://doi.org/10.6827/NFU.2010.00025

摘要

本研究利用磁控共濺鍍法在p-type Si (100)上沈積Cu(CoN)合金薄膜，並利用RTA在N2/H2(5%)氣氛下300-700˚C熱處理持溫10與30分鐘，合金薄膜並以FPP測量片電阻值、利用SEM觀察表面形貌、XRD分析晶體結構、附著性測試評估薄膜附著性、TEM觀察界面擴散情形、VSM量測薄膜磁性、I-V量測薄膜漏電流，探討製程N2含量及退火溫度對Cu(CoN)合金薄膜之特性影響。
結果顯示製程N2氣體比例高於40%所得之Cu82.3Co3.4N14.3、Cu79.9Co4.7N15.4、Cu81.4Co2.6N16.0、Cu79.3Co4.4N16.3、Cu75.8Co6.5N17.7、Cu81.9Co3.3N14.8、Cu80.1Co3.8N16.1合金薄膜經熱處理皆有2Cu3N→6Cu+N2(g)相分解反應(相轉變)，但此相分解卻易於使Cu擴散與Si反應並造成漏電流增加，雖然提高N含量能有效抑制Cu顆粒過度成長與孔洞產生而免於聚集，但未有理想阻擋Cu擴散與提升附著性之效果，其中具有較佳阻擋效果與低電阻率為Cu95.7Co4.3、Cu92.5Co1.9N5.6、Cu92.0Co2.5N5.5合金薄膜，薄膜經500˚C熱處理持溫10分鐘可分別降低為5.0 μΩcm、3.1 μΩcm、4.2 μΩcm，熱處理500˚C持溫30分鐘可分別降低為4.7 μΩcm、3.1 μΩcm、3.5 μΩcm，而Cu88.9Co3.4N7.7合金薄膜經600˚C熱處理持溫10分鐘與熱處理500˚C持溫30分鐘可分別降低為4.6 μΩcm與4.5 μΩcm，Cu87.2Co3.8N9.0合金薄膜經500˚C熱處理持溫10與30分鐘可降低電阻率為5.5 μΩcm與4.6 μΩcm並提升附著性，且Cu87.2Co3.8N9.0/SiO2/Si/Al經600˚C熱處理持溫10與30分鐘可降低漏電流且能維持熱穩定性，此合金薄膜有潛力應用於無擴散阻障層之銅製程。
另外以反應性磁控共濺鍍方式沈積CoN與Cu/CoN薄膜於p-type Si (100)晶片上，後續製程以RTA在N2/H2(5%)氛壓500 torr下進行300-800˚C恆溫5分鐘之熱處理。實驗結果以不同N2比例製備之CoN薄膜經700-800˚C熱處理5分鐘會使Co2N結晶相分解為Co結晶相，並造成薄膜表面產生許多孔洞與呈現島狀Co顆粒聚集情形；隨N2比例增加確實能逐漸提高失效溫度，而有效防止Cu擴散與Si反應並維持熱穩定性，其中以N2比例為10%、20%與50%之Cu/Co84.5N15.5/Si、Cu/Co82.2N17.8/Si與Cu/Co79.2N20.8/Si效果較佳，其失效溫度分別為675˚C、675˚C與700˚C。

關鍵字

磁控共濺鍍 ； 銅鈷氮合金薄膜 ； 氮化鈷 ； 阻障層

並列摘要

Cu(CoN) alloy thin films were deposited on p-type Si (100) substrates by magnetron reactive co-sputtering under various ambient Ar+N2, and the films were annealed in an ambient N2+H2(5%) at a temperature between 300-700˚C using a Rapid Thermal Annealer (RTA). The sheet resistance of the film was measured by FPP, the surface morphology was observed by SEM, crystal structure was analyzed by XRD, interface diffusion was observed by TEM, magnetic property was measurement by VSM, adhesion was evaluated by Scotch Tape Test, and leakage current was measured by I-V.
The effects of ambient N2 and annealing temperature on the properties of Cu(CoN) alloy thin films have been investigated, and the results showed that Cu82.3Co3.4N14.3, Cu79.9Co4.7N15.4, Cu81.4Co2.6N16.0, Cu79.3Co4.4N16.3, Cu75.8Co6.5N17.7, Cu81.9Co3.3N14.8 and Cu80.1Co3.8N16.1 thin films exhibited the decomposition (phase transformation) of 2Cu3N→6Cu+N2(g) at an elevated temperature, but the dissociation of Cu3N caused the reaction between Cu and Si, and therefore increasing the leakage current. Although a high nitrogen-content Cu(CoN) film inhibit Cu aggregation, it is unable to prevent Cu from diffusion. The Cu95.7Co4.3, Cu92.5Co1.9N5.6 and Cu92.0Co2.5N5.5 alloy thin films had better barrier properties and lower resistivities. The resistivity of Cu95.7Co4.3, Cu92.5Co1.9N5.6 and Cu92.0Co2.5N5.5 thin film was 5.0 μΩcm, 3.1 μΩcm and 4.2 μΩcm after 500˚C annealing for 10 min, and resistivity was 4.7 μΩcm, 3.1 μΩcm and 3.5 μΩcm after annealing at 600˚C for 30 min, respectively. Cu88.9Co3.4N7.7 alloy thin film exhibited a good adhesion characteristic, and had a resistivity of 4.6 μΩcm and 4.5 μΩcm when the film was annealed at 600˚C for 10 min and 500˚C for 30 min, respectively. Having annealed Cu87.2Co3.8N9.0/SiO2/Si/Al, the film remained high thermal stability and low leakage current. The film is potentially to be used in the barrierless Copper interconnection.
Co-N film was also evaluated as a barrier. The Co2N was decomposed into Co, and therefore formed many voids and Co islands on the surface after annealing the film at 700-800˚C for 5 min. The film prepared in a high ambient N2 had a high failure temperature and exhibited the thermal stability to prevent Cu diffusion from reacting with Si. Cu/Co84.5N15.5/Si, Cu/Co82.2N17.8/Si and Cu/Co79.2N20.8/Si exhibited the high thermal stability and the failure temperature was 675˚C, 675˚C and 700˚C, respectively.

並列關鍵字

reactive magnetron co-sputter ； Cu(CoN) alloy thin film ； cobalt nitrides ； diffusion barrier

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