本研究主要提出一種新穎的二階段化學氣相沉積(Metal-Organic Chemical Vapor Deposition)成長銅晶種層(Seed layer)於氮化鉭(TaNx)阻障層薄膜的應用之可行性評估。首先以自行合成的Cu(hfac)2為先驅物，沉積時外加添加物沉積(Cu2O+Cu)薄膜再用乙醇當還原劑還原成銅薄膜。之後觀察沉積溫度與沉積時間(Cu2O+Cu)和銅薄膜之表面型態、結晶結構、薄膜電阻值及化學組成O/Cu比之影響，以尋求符合銅製程中成長晶種層的製程需求。
首先在合成先驅物方面，由自行合成和購買的FT-IR、DSC和TGA實驗結果顯示出自行合成的先驅物有極高的純度。之後利用自行合成的先驅物進行二階段沉積薄膜，由實驗結果所顯示在第一階段不同沉積溫度下，以水為外加物成長的薄膜，由XPS定量分析得到皆為氧化亞銅(Cu2O)和金屬銅(Cu)的混合，在250℃時金屬銅含量為28.39 at.%，而且隨著沉積溫度的上昇，金屬銅原子的含量也隨之提高；在沉積溫度250~275℃之間，皆可以成長緻密且連續的(Cu2O+Cu)薄膜，其顆粒大小為28~45nm之間：在第二階段還原反應中，以乙醇為還原劑，相同溫度還原(Cu2O+Cu)薄膜，其結果得到在任何溫度下還原，由XPS分析得到皆為高純度的金屬銅，而沉積溫度275℃之前，顆粒大小和表面粗糙度並沒有太大的變化，而到了300℃之後，顆粒開始聚集，其顆粒大小和表面粗糙度為110 nm和15.27 nm。
而沉積時間效應是固定在沉積溫度275℃下二階段成長銅薄膜，隨著沉積時間上升，銅膜厚度也隨之上升。在沉積時間5分鐘以後才會形成連續的薄膜，而沉積15分鐘之後，顆粒因為表面自由能的上升而開始聚集，沉積時間30分鐘後，顆粒大小為98nm。而由四點探針量測不同時間和溫度下的片電阻值發現隨著沉積時間和溫度的增加，片電阻隨之下降。在沉積溫度300℃，沉積時間30分鐘可以獲得一最低之電阻率2.78 μΩ-cm。
由實驗結果所顯示的不同比例外加物效應是在固定沉積溫度260℃下二階段成長銅膜，隨著乙醇比例的增加，第一階段中(Cu2O+Cu)薄膜內所含的金屬銅也會隨之提高，但是無法一階段直接還原成銅膜，而在第二階段利用乙醇當還原劑，不同比例外加物所成長的(Cu2O+Cu)薄膜皆可以還原成高純度的銅膜，由此而推導出二階段成長的反應機制。此外，隨著乙醇比例的上升，沉積速率也跟著加快，而顆粒大小並未有明顯的改變。
利用此二階段成長方式成長銅晶種層於氮化鉭溝槽(trenches)中，由SEM微影像照片觀察到在沉積溫度260和275℃時都可以成長平坦且連續的晶種層，再利用電鍍銅的方式將成長晶種層的trenches填滿，發現到在電流密度20~10 mA/cm2時，trenches會產生孔洞(void)，而電流降到7 mA/cm2時，可以將trenches填滿。之後由銅/氮化鉭/矽多層膜系統的銅膜附著能量測，發現在不同沉積溫度下，隨著沉積溫度的上升，銅膜和TaNx的平均接觸角也隨之上升，而附著能隨之下降；由以上實驗可知本研究成功的建立一套新的銅製程中成長晶種層之製程方法。

The feasibility of using a novel metal-organic chemical vapor deposition (MOCVD) technique to achieve the deposition of a thin and conformal copper film was examined. The deposition procedure consisted of two consecutive steps: an oxide deposition step followed by a reduction step. Copper(II)-1,1,1,5,5,5-hexafluoro-acetylacetonate hydrate (Cu(hfac)2•xH2O) was used as the copper precursor and the additive. The preformed copper oxide thin film was reduced to an elemental copper metal film through exposure to ethyl alcohol. Experiments results indicate that the surface morphology, crystalline structure, film resistivity, and chemical composition of the deposited (Cu2O+Cu) and Cu films.
Self-synthesis of Cu(hfac)2•xH2O and characterization with FT-IR、DSC、TGA where performed and Cu(hfac)2•xH2O was confirmed to be the product. In additional, the deposition of thin films on TaNx substrates was achieved in a cold-wall CVD reactor. The results of thin films deposition show that the concentration of metal Cu increased with the raise of the reaction temperature. At 250~275℃, the surface morphology of the (Cu2O+Cu) film was smooth and continuous. The morphology of Cu2O films obtained at 300℃ changed considerably, with large and well defined grains as depicted in the SEM image. After reducing step, the (Cu2O+Cu) film was completely reduced to the Cu film by alcohol. SEM and AFM indicate that the increase of roughness and grain sizes with the raise of temperature. The grain size and RMS were increased up to 110nm and 15.27 nm at 300℃.
The effect of deposition time on Cu films at 275℃ was that the thickness of Cu films increased with the deposition time. The surface morphology of the Cu film was smooth and continuous after 5 minute of deposition time. The grain size of Cu film increased with the deposition time. The grain size of Cu for 30 minutes of deposition time was 98 nm. In additional, the result shows that the best resistivity is 2.78 µΩ-cm at 300℃ for 30 minute of deposition time..
The preformed (Cu2O+Cu) thin film was reduced to an elemental copper metal film through exposure to ethyl alcohol. The proposed two-step MOCVD method was found to succeed in forming smooth and continuous thin copper films.
With the addition of ethyl alcohol, however, the (Cu2O+Cu) film was not reduced to the Cu metal film as expected. The preformed (Cu2O+Cu) film can only be reduced to an elemental Cu metal film through exposure to ethyl alcohol alone during a second step, i.e. the reduction step. In the current study, also found is that the metallic Cu concentration in (Cu2O+Cu) films and the deposition rate of (Cu2O+Cu) films increased with the raise of the ethyl alcohol mole fraction in the additive, a mixture of ethyl alcohol and water. These experimental results indicate that Cu(hfac)2•xH2O competes with ethyl alcohol for adsorption on the same metallic Cu active sites, and Cu(hfac)2•xH2O adsorbs much more strongly than ethyl alcohol. Based on these phenomena, the deposition mechanisms of the two-step MOCVD of Cu films can be determined.
The deposition of Cu films on TaNx trench substrates at 260~300℃ was conducted to demonstrate the applicability of this two-step MOCVD technique on patterned wafers. The deposited film was conformal and the step coverage was excellent. The electrodeposited Cu was used on the two-step MOCVD seed layer trenches. The deposited Cu completely fills these structures and no voids can be observed. To realize the Cu surface adhesive energies on TaNx films at different deposition temperature, we adopted the SEM observation, Young-Dupre equation. Experiment results indicated that Cu adhesive energies decreased with deposition temperature.
Finally, from our experiment results two-step MOCVD method succeeds in forming smooth and continuous thin copper films, which be used as high-quality seed layers for electroplating.

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