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1 2005/3/6吳志偉吳志偉1 NTOU Aquatic NEMS Research Center Nanotechnology 吳志偉吳志偉 國立台灣海洋大學機械與機電工程學系國立台灣海洋大學機械與機電工程學系 Tel02-24622192-3253 Email wuchihwemail.ntou.edu.tw 2005/3/6吳志偉吳志偉2 NTOU Aquatic NEMS Research Center StrategyStrategy Top Down Approaching Bottom Up Approaching 2 2005/3/6吳志偉吳志偉3 NTOU Aquatic NEMS Research Center NanomotorsNanomotors A series of scanning electron microscope pictures of the spinning rotor of a nanomotor fabricated in the lab of UC Berkeley physicist Alex Zettl. The entire electric motor is about 500 nanometers across, 300 times smaller than the diameter of a human hair.Credit Zettl lab Ref http//www.berkeley.edu/news/media/releases/2003/07/23_motor.shtml Nanomechanical machines and devices are in the early stages of development, and many are still in conceptual stages 2005/3/6吳志偉吳志偉4 NTOU Aquatic NEMS Research Center Flagellar MotorFlagellar Motor The motor is not driven by electromagnetic forces, but rather by the breakdown of ATP, which causes a change in the shape of the molecules. Applying the energy gain from ATP to a molecular ratchet enables the protein shaft to rotate. Perhaps the study of biological nanomachines will provide insights that will enable us to improve the design of mechanical nanomachines. 3 2005/3/6吳志偉吳志偉5 NTOU Aquatic NEMS Research Center Nanoimprint Lithography 高分子材料之簡介 Nanoimprint Lithography 高分子材料之簡介 高分子的特性 質量輕 絕緣性和腐蝕抵抗性 佳 易加工成複雜的產品 可撓曲 低強度 （受外力易產生潛變） 對溫度敏感 高分子Polymer這個名稱起源自希臘文，意思是許多 Poly部分Mer，即高分子是由無數的單分子以長鏈 狀態形成的物質。 泛用材料泛用材料 PE PP PVC PS 中等材料中等材料 PMMA ABS 工程材料工程材料 PC NYLON 2005/3/6吳志偉吳志偉6 NTOU Aquatic NEMS Research Center Nanoimprint Lithography 高分子材料的種類 Nanoimprint Lithography 高分子材料的種類 高分子高分子 塑膠塑膠 橡膠橡膠 熱塑性體熱塑性體 熱固性體熱固性體 無定形體無定形體 半結晶體半結晶體 熱塑性塑膠由長鏈狀的碳原子所組成（藉由加熱使其軟化而 加工成型） 熱固性塑膠由網路狀的碳原子所組成（藉由化學反應產生硬 化而成型） 4 2005/3/6吳志偉吳志偉7 NTOU Aquatic NEMS Research Center Nanoimprint Lithography 高分子材料的玻璃轉移溫度（ Nanoimprint Lithography 高分子材料的玻璃轉移溫度（Tg）） 玻璃轉移溫度是指塑料微觀高分子鏈開始具有運動現象的溫度 。若溫度低於玻璃轉移溫度，分子鏈的運動大部分被凍結，塑 料呈現剛性硬脆之玻璃態；若溫度高於玻璃轉移溫度，分子鏈 可自由運動，塑件呈現柔軟可撓曲的橡膠態，因此玻璃轉移溫 度為塑料發生玻璃態- 橡膠態相轉移的溫度。 2005/3/6吳志偉吳志偉8 NTOU Aquatic NEMS Research Center Nanoimprint LithographyNanoimprint Lithography 奈米壓印係利用一具有奈米結構之模具，直接壓印 在一薄光阻層上，使模具上的圖形轉移至基板，再 利用非等向性蝕刻如RIE的方法，清除底部殘餘的 光阻材料，即可獲得奈米等級的微結構。 Stephen Y. Chou , Peter R. Krauss , and Preston J. Renstrom 5 2005/3/6吳志偉吳志偉9 NTOU Aquatic NEMS Research Center 於壓印前在壓印模版上處理表面活性較低的離形劑於壓印前在壓印模版上處理表面活性較低的離形劑 如FT D S或是OT S，將矽晶圓表面官能基由- OH 轉變成- C F3、- C H3的 官能基，以利壓印結束能輕易與阻劑離形，完成阻劑圖案轉移。 分析結果指出經OT S處理過，接觸角由∼40 增加至∼1 07 。 如FT D S或是OT S，將矽晶圓表面官能基由- OH 轉變成- C F3、- C H3的 官能基，以利壓印結束能輕易與阻劑離形，完成阻劑圖案轉移。 分析結果指出經OT S處理過，接觸角由∼40 增加至∼1 07 。 步驟步驟 1 .將矽晶圓依次浸入絕對酒精/ 二次水 1 1 v / v ，並以超音波震 洗機震盪2 0分鐘後，以氮氣吹乾確實去除晶圓上的雜質與水氣。 將矽晶圓依次浸入絕對酒精/ 二次水 1 1 v / v ，並以超音波震 洗機震盪2 0分鐘後，以氮氣吹乾確實去除晶圓上的雜質與水氣。 2 .將之浸入OT S 溶於n - h e x a n ，1 m M 的溶液中，於乾燥環境靜置4h r 。將之浸入OT S 溶於n - h e x a n ，1 m M 的溶液中，於乾燥環境靜置4h r 。 壓印模版的前處理壓印模版的前處理 2005/3/6吳志偉吳志偉10 NTOU Aquatic NEMS Research Center 1.Hot Embossing Lithography 2.Mold-Assisted Lithography 3.Mirrocontact Printing OverviewOverview 6 2005/3/6吳志偉吳志偉11 NTOU Aquatic NEMS Research Center 奈米壓印微影技術之製程特性與限制奈米壓印微影技術之製程特性與限制 製程簡易，適合大量生產。 無傳統光微影技術之缺點（光繞射問題）。 可製作高深度之微結構，且結構之側壁近乎垂直。 最高的解析度為10nm。 目前只適合製作2D的微奈米結構。 製程上需要較高度的真空環境。 壓印溫度、壓印壓力的控制及機台的穩定性要求很 高。 EVG520HE Nanoimprinting System 2005/3/6吳志偉吳志偉12 NTOU Aquatic NEMS Research Center 奈米壓印微影技術之應用實例奈米壓印微影技術之應用實例 7 2005/3/6吳志偉吳志偉13 NTOU Aquatic NEMS Research Center Scanning Tunneling MicroscopyScanning Tunneling Microscopy 掃瞄穿隧顯微術, STM 1980年代初期由IBM蘇黎世實驗 室所發展 提供物體表面原子結構影像 探針式 優點 非破壞式, 樣本不需前處理, 可 在各種環境下操作, 造價低, 體 積小, 設計彈性高 缺點 電絕緣體或表面高度落差過大 的材料不適用, 掃瞄速度慢, 產 品成熟度及穩定性也還不夠 2005/3/6吳志偉吳志偉14 NTOU Aquatic NEMS Research Center Quantum Tunneling EffectQuantum Tunneling Effect 量子穿隧效應 Classic Mechanics 一個處於能量較低的粒子根本不 可能越過Vo能量障礙到達另一邊 Quantum Physics 電子可能穿透一個能障, 其穿透機率與能障的高度和寬度 有關 薛丁格方程式, Schroedinger’s euqation 以機率波動來描述粒子, 故當兩個電極的距離很接近時, 電子能從電極間穿透.對一般金屬而言, 1埃的間距差可導 致電流10倍的增減. E電子能量,d兩電極間距, I穿隧電流 2 , kz m VE eK h − Ψ 2 2kd I de∝ Ψ 8 2005/3/6吳志偉吳志偉15 NTOU Aquatic NEMS Research Center 成像方式成像方式 constant current mode 以設定的穿隧電流作為回饋訊號。此時當探針在樣品表 面作掃描動作時，探針為了保持固定的電流值大小，而 必須隨著樣品表面之起伏調整其高度值的大小；因此， 以探針的高度變化來作為樣品表面的呈像方式，便能反 映出樣品表面的形貌。 優點 可容忍待掃描樣品較大的表面高低變化 缺點 由於必須以回饋信號作為調制，因此掃描速度較慢， 容易受到低頻雜訊干擾 2005/3/6吳志偉吳志偉16 NTOU Aquatic NEMS Research Center 成像方式成像方式 constant height mode 直接以穿隧電流值的變化來作為表面形態的呈像。當探 針以固定的設定高度掃描樣品的表面時，由於樣品表面 的高低變化，導致探針和樣品表面的間距時大時小，此 時穿隧電流值也隨之改變 優點 可做快速掃描以補捉一些表面動態 缺點 若掃描範圍內的樣品表面起伏太大，則極容易損壞探 針 9 2005/3/6吳志偉吳志偉17 NTOU Aquatic NEMS Research Center 成像方式成像方式 current imaging tunneling spectroscopy 以定電流作為架構，讓探針在回饋系統的控制之下，於 掃描樣品表面的過程中保持一定的探針與樣品間的間距。 然後於每一點，瞬間切斷回饋作用，並且利用這段期間， 將偏壓在預定的範圍內作調變動作，同時記錄不同偏壓 所產生之穿隧電流值的大小，將某一偏壓在掃描範圍內 各點的電流組合起來，即構成一符二維電流密度分布圖 優點 結合定電流取像法與定高度取像法， 缺點 因為回饋系統必須不斷地開關，因此較為費時，並且 每作一次，其實等於儲存了上百個影像的資訊，因此 記憶體容量的需求量很大 2005/3/6吳志偉吳志偉18 NTOU Aquatic NEMS Research Center Quantum Corral and MirageQuantum Corral and Mirage Fe/Cu111 M.F. Crommie, C.P. Lutz, D.M. Eigler Science 262 1993 218 Co/Cu111 H.C. Monoharan, C.P. Lutz, D.M. Eigler Nature 403 2000 512 Xe/Ni111 D.M. Eigler E.K. Schweizer Nature 344 1990 524 10 2005/3/6吳志偉吳志偉19 NTOU Aquatic NEMS Research Center Quantum CorralQuantum Corral Using STM, 48 iron atoms a circle of 7.3 nm radius on copper surface. Group of electrons are free to move on surface to 2D electron gas. When meet iron atoms, electrons are partially reflected. Corral trapped electrons into quantum states. 2005/3/6吳志偉吳志偉20 NTOU Aquatic NEMS Research Center Nano TaiwanNano Taiwan 700nmx700nm, Au The surface of the material has to be cooled to liquid helium temperatures in order to reduce thermal vibrations, which may cause the atoms to diffuse thermally, thereby disturbing the arrangement of atoms being assembled. Because the building of 3D structures has not yet been achieved, the slowness of the technique together with the need for liquid helium cooling and high vacuum all indicate that STM manipulation is a long way from becoming a large-scale fabrication technique for nanostructure. Ref 中研院, 物理所, 張添智 11 2005/3/6吳志偉吳志偉21 NTOU Aquatic NEMS Research Center CNT Bundles and RopeCNT Bundles and Rope CNT bundles can be imaged as an array of SWNT aligned along a common axis A collection of these intertwined bundles of SWNTs is called a nanotube rope 2005/3/6吳志偉吳志偉22 NTOU Aquatic NEMS Research Center Mechanical Properties of CNTMechanical Properties of CNT The Young’s modulus for an individual 10, 10 nanotube is 0.64 TPa Small-diameter nanotube ropes extended elastically by 5.8 before breaking, the SWNT strength calculated from the product of this strain and modulus is 37 GPa, which is close to the maximum strength of silicon carbide Thermal conductivity for an individual MWNT 3000 W/mK is greater than the nature diamond2000 W/mK The carrier mobility is about 10000 cm2/Vs, which is 20 times higher than silicon 12 2005/3/6吳志偉吳志偉23 NTOU Aquatic NEMS Research Center CNT MicroactuatorCNT Microactuator Application of an AC voltage produced an oscillation of the cantilever. Bimorph cantilever actuator The device response depends on the expansion of opposite electrodes. This actuator is neither a NEMS nor MEMS device because of the size of the electrodes. fo resonant frequency, 20-30GHz As the frequency increases, the amplitude decreases Picometer to femtometer Optical is not valid E elastic modulus ρ the density b the thickness L the beam length 12 2 o Eb f Lρ ∼ 2005/3/6吳志偉吳志偉24 NTOU Aquatic NEMS Research Center CNT MicroactuatorCNT Microactuator As the frequency increases, the amplitude decreases from picometer to femtometer Optical reflection s are not applicable because of the diffraction limit. Mechanical motion is detected by a change in capacitance. It is not clear that such a transducer can detect displacements as small as picometer to femtometer, and do so at frequencies up to 30 GHz The small effective mass of a nanometer-sized beam renders its resonant frequency extremely sensitive to slight changes in its mass 13 2005/3/6吳志偉吳志偉25 NTOU Aquatic NEMS Research Center Mechanical VibrationMechanical Vibration Md2Xt/dt2bdXt/dtKXt0 1 22 expcos 2 2 bt x wAwt M Kb w MM δ − − − A major source of damping will be air resistance, which is proportional to the area of the beam. For a nanosized beam, the damping factor b is small. It dissipate very little energy over their over their vibration cycles. 2005/3/6吳志偉吳志偉26 NTOU Aquatic NEMS Research Center AFM –AFM –Atomic Force MicroscopeAtomic Force Microscope 原子力顯微鏡atomic force microscope, AFM是利用特製微 小探針，檢測探針與樣品表面間的力交互作用，使探針 在樣品表面來回掃描偵測，並利用此掃描器的垂直微調能 力及回饋迴路，讓探針與樣品間的交互作用在掃描過程中 保持一定距離約10-10m，只要紀錄掃描面上每一點的垂 直微調距離，便可獲得樣品表面的等交互作用圖像，進而 推導出樣品表面特性。 14 2005/3/6吳志偉吳志偉27 NTOU Aquatic NEMS Research Center SARSSARS SA R S冠狀病毒在接觸「台大抗煞一號」化合 物後，套膜會很快崩解而失去致病性 2005/3/6吳志偉吳志偉28 NTOU Aquatic NEMS Research Center AFM image of erythrocytes, ground-squirrel’s blood. 50.1x53.5 m and 12.5x13.0 m scans size. ErythrocyteErythrocyte 15 2005/3/6吳志偉吳志偉29 NTOU Aquatic NEMS Research Center Molecular and Supramolecular Switch 2005/3/6吳志偉吳志偉30 NTOU Aquatic NEMS Research Center Molecular and Supramolecular Switch Molecular and Supramolecular Switch The lithographic techniques used to make silicon chips for computers are approaching their limits in reducing the sizes of circuitry on chip. Nanosize architecture is become more difficult and more expensive to make. A molecular that can exist in two different states and can be converted reversibly between the two states by external stimuli, such as light or voltage, can be used to store ination. The change between the states must be fast and reversible by external stimuli. The two states must be thermally stable and be able to switch back and forth many times. 16 2005/3/6吳志偉吳志偉31 NTOU Aquatic NEMS Research Center 偶氮苯 Azobenzene SwitchAzobenzene Switch Molecular switch The cis or azobenzene is not thermally stable, and a slight warming causes it to return to the trans , so a optical s of switching are not of practical use for applications in computing. 2005/3/6吳志偉吳志偉32 NTOU Aquatic NEMS Research Center Azobenzene SwitchAzobenzene Switch Molecular switch Employing electrochemical oxidation and reduction can overcome this thermal instability. The cis isomer is reduced to hydrazobenzene by the addition of hydrogen atoms at a more anodic negative potential, and then converted back to the trans isomer by oxidation, which removes the hydrogen atoms. 17 2005/3/6吳志偉吳志偉33 NTOU Aquatic NEMS Research Center Chiroptical Molecular SwitchChiroptical Molecular Switch Using circularly polarized light CPL to bring changes between isomers. Linearly polarized light LPL can be used to read The system can be erased using unpolarized light UPL 2005/3/6吳志偉吳志偉34 NTOU Aquatic NEMS Research Center Spiropyran Molecular SwitchSpiropyran Molecular Switch Conational changes involving rearrangements of the bonding in a molecule can also be the basis of switch. When the colorless spiropyran is subjected to UV light, the carbon-oxygen bond opens, ing merocyanine. When the merocyanine is subjected to visible light or heat, the spiropyran res. 18 2005/3/6吳志偉吳志偉35 NTOU Aquatic NEMS Research Center Electric moleculesElectric molecules The STM has been used to measure the conductivity of long chainlike molecules. A monolayer of octanethiol was ed on a gold surface by self-assembly. A gold-coated STM tip was scanned over the top of the monolayer, ing an electric circuit between the tip and the flat gold surface. The current is quite low, and the resistance of the molecule is estimated to be 900MΩ 2005/3/6吳志偉吳志偉36 NTOU Aquatic NEMS Research Center Electric moleculesElectric molecules The result was observed at 60K but not at room temperature. A molecular can conduct electricity, and that the conduction can be switched on and off, is not enough to develop a computer. 19 2005/3/6吳志偉吳志偉37 NTOU Aquatic NEMS Research Center Roxatane Molecule SwitchRoxatane Molecule Switch An aluminum electrode was made by lithographically patterning 0.6 um diameter aluminum wires on a silica substrate. This electrode was then exposed to oxygen to allow a layer of Al2O3to on it. 5um layer of titanium followed by a thicker layer of aluminum were evaporated through a contact mask using electron beam deposition. 2005/3/6吳志偉吳志偉38 NTOU Aquatic NEMS Research Center Current-Voltage CharacteristicsCurrent-Voltage Characteristics The application of –2V, the read mode, caused a sharp increase in current. The switch could be opened by applying 0.7V The difference in the current between the open and closed switch was a factor of 60-80.
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