利用自組裝單層膜達成區域選擇性原子層沉積與原子層轟擊技術對高介電常數薄膜性質影響之研究

Area-Selective Atomic Layer Deposition by Self-Assembled Monolayer and High-K Thin Films Gate Dielectrics Treated with Atomic Layer Bombardment

岳亞芝(Ya-Zhi Yue)

指導教授 ： 陳敏璋

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104010

摘要

本論文主要分為兩個部分，第一部分為利用液相沉積的自組裝單分子膜達成區域選擇性原子層沉積。首先，將鈷、鉑試片浸至配製好的自組裝分子溶液中，並優化自組裝單分子膜液相沉積的條件，透過水滴接觸角及X射線光電子能譜分析自組裝單分子膜的品質，以決定最佳的沉積條件；在此條件沉積自組裝單分子膜時，1-十二烷硫醇分子會完全取代金屬表面的氧化層，以化學吸附的方式吸附於表面。接著，測試鉑及鈷上自組裝單分子膜的熱穩定性，透過水滴接觸角分析自組裝單分子膜是否劣化，發現自組裝單分子膜在鈷上的熱穩定性較在鉑上佳。最後根據熱穩定性的結果選擇適當的條件來進行原子層沉積，並以X射線光電子能譜分析自組裝單分子膜阻擋氧化層沉積的功能。由於1-十二烷硫醇選擇性吸附於金屬表面，使鈷及鉑表面呈現疏水性，因此，在鈷的表面，1-十二烷硫醇能在150 °C阻擋30 cycles的氧化鋁及10 cycles的氧化鋯的沉積，且在180 °C及200 °C分別阻擋10 cycles及5 cycles的氧化鋁的沉積；另一方面，在鉑的表面，1-十二烷硫醇能在120 °C阻擋10 cycles的氧化鋁的沉積。反之，由於1-十二烷硫醇不會吸附於二氧化矽表面，因此導致與鈷、鉑表面對氧化鋁和氧化鋯的沉積有選擇性的差異。
第二部分則研究原子層轟擊技術。原子層轟擊技術為在以飽和電漿時間沉積介電層的製程中，於每個原子層沉積循環引入額外的電漿處理。本研究比較以具有化學活性氣體或是惰性氣體電漿進行原子層轟擊，對氧化鋯及氧化鉿介電層性質造成的影響，並進一步測試電容元件的電性表現。由X光反射率分析氧化鉿薄膜密度得知，以惰性氣體電漿進行原子層轟擊，使得薄膜密度提升，並導致電容元件的漏電流密度下降約1個數量級。

關鍵字

區域選擇性原子層沉積 ； 1-十二烷硫醇 ； 自組裝單分子膜 ； 高介電係數介 電層 ； 電漿處理 ； 原子層沉積技術

並列摘要

This thesis is divided into two parts. In the first part, self-assembled monolayers (SAMs) were prepared from the liquid phase and used to passivate the metal surface to achieve area-selective atomic layer deposition (AS-ALD). Firstly, cobalt (Co) and platinum (Pt) substrates were immersed into a solution containing alkyl thiols to de-posit a layer of thiol SAMs. Factors influencing the formation of 1-dodecanethiol (DDT) SAMs on the metal surfaces were investigated to optimize the quality of the SAM layer. The water contact angle measurement and the X-ray photoelectron spec-troscopy (XPS) were performed to analyze the quality of SAMs, from which the opti-mal condition of the SAM formation by liquid-phase can be known. Secondly, in order to determine appropriate processing conditions for AS-ALD, the thermal stability of DDT SAMs on the Co and Pt surfaces was tested. It is found that the thermal stability of the DDT-treated Co surface is superior to that of the DDT-treated Pt surface. Finally, the blocking ability of the DDT-treated surface was evaluated by the Al2O3 and ZrO2 ALD processes. The XPS analyses reveal that the DDT-assisted blocking for ALD can be achieved on the Co and Pt surfaces. At the ALD deposition temperature of 120°C, DDT prevents the Al2O3 deposition on the Pt surface for at least 10 ALD cycles. At 150°C, DDT blocks the deposition of Al2O3 and ZrO2 on Co at least for 30 cycles and 10 cycles, respectively. At 180°C, no Al XPS signal was detected from the DDT-treated Co surface after performing 10 ALD cycles of Al2O3. The DDT-treated Co surface exhibits the blocking ability for the Al2O3 deposition of 5 ALD cycles at 200°C. Since the DDT SAMs were selectively formed on the metal and SiO2 surfaces, AS-ALD between the SiO2 and Co/Pt surfaces can be achieved by using DDT SAMs.
The second part of this thesis investigates the impact of atomic layer bombard-ment (ALB), which is the layer-by-layer and in-situ plasma treatment introduced in each ALD cycle, on the dielectric properties of the high-K thin films such as ZrO2 and HfO2. This study investigates the impacts of ALB based on the chemically active gas or inert gas plasma on the properties of high-K dielectric thin films. As compared with the untreated HfO2 thin film, the X-ray reflectometry analysis shows that the Ar/He ALB treatment gives rise to an increase in the film density, which leads to the reduc-tion of the leakage current density by ∼1 order of magnitude.

並列關鍵字

area-selective atomic layer deposition (AS-ALD) ； 1-dodecanethiol (DDT) ； self-assembled monolayers (SAMs) ； high-K dielectrics ； plasma treatment ； atomic layer deposition (ALD)

參考文獻

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