1321805 九、發明說明： 【發明所屬之技術領域】1321805 IX. Description of invention: [Technical field to which the invention belongs]
C 本發明涉及一種場發射陰極的製備方法，尤其涉及一 種基於奈米碳管的場發射陰極的製備方法。 【先前技術】 • 奈米碳管係一種新型碳材料，其具有極其優異的導電 性月b，且其具有幾乎接近理論極限的尖端表面 _小，其局《場越針），故，奈米碳管係已知最好的 1 場發射材料，其具有極低場發射，可傳輸極大電流密 纟’且電流極穩定，因而非常適合做場發射顯示器的發射 組件。 用於發射元件的奈米碳管，一般為採用電弧放電法或 化學氣相沈積法(CVD法）生長的奈米碳管。將奈米碳管應 用於場發射顯示H的方^有：將含有奈米碳管的導電浆料 或者有機粘接劑印刷成圖形通過後續處理使得奈米碳管能 ( 夠從漿料的埋藏中露出頭來成發射體。在此方法中，將含 有奈米碳管的導電漿料以厚膜鋼板印刷的方式塗布在導電 基板上，奈米碳管在漿料中發生彎曲，相互交織不易形 成垂直於導電基板的奈米碳管，為形成性能良好的發射尖 端’需對奈米碳管陣列進行後續處理，即將一層漿料剝離， 從而使奈米碳管從漿料的埋藏中露出頭來而成為發射體， 惟’剝離此漿料層對奈米碳管損傷很大。 另，上述方法製備的奈米碳管層中，奈米碳管基本上 队在導電基板上，相對導電基板垂直的奈米碳管較少。然 6 1321805The present invention relates to a method of preparing a field emission cathode, and more particularly to a method for preparing a field emission cathode based on a carbon nanotube. [Prior Art] • Nano carbon tube is a new type of carbon material with extremely excellent conductivity month b, and its tip surface is almost close to the theoretical limit _ small, its "field needle", so, nano The carbon tube is the best known 1 field emission material with very low field emission, which can transmit a very large current density and is extremely stable, making it ideal for use as a transmitter component for field emission displays. The carbon nanotubes used for the emitting elements are generally carbon nanotubes grown by arc discharge or chemical vapor deposition (CVD). The application of the carbon nanotubes to the field emission display H is: printing the conductive paste or organic binder containing the carbon nanotubes into a pattern, and the carbon nanotubes can be sterilized from the slurry by subsequent processing. In this method, the conductive paste containing the carbon nanotubes is coated on the conductive substrate by printing on a thick film steel plate, and the carbon nanotubes are bent in the slurry, and it is difficult to interweave them. Forming a carbon nanotube perpendicular to the conductive substrate, in order to form a good performance of the emitter tip, the carbon nanotube array needs to be subsequently processed, that is, a layer of the slurry is peeled off, so that the carbon nanotubes are exposed from the burying of the slurry. It is an emitter, but the 'stripping of the slurry layer is very damaging to the carbon nanotubes. In addition, in the carbon nanotube layer prepared by the above method, the carbon nanotubes are basically on the conductive substrate, and the opposite conductive substrate Vertical carbon nanotubes are less. 6 1321805
而奈米碳管作為場發射體 發射出電子，故，太奸〜=不未石厌管的一端沿軸向 管場發射性能的發揮。、反S導電基板上不利於奈米破 有寥於此，碟有必要提供一種 =;=陰極的，方法，其不損傷奈米碳管： 管場：能電基板基本垂直’從而確保奈米碳 【發明内容】 β 一種場發射陰極的製備方法，其包括以下步驟: 提供基底，在上述基底表面形成一導電薄膜層；形 成一光吸收層於上述導電薄膜層上；形成—催化劑層 於上述光吸收層上；通人碳源氣與載氣的混合氣體流 經上述催化劑層表面；以及以雷射光束聚焦照射基底 從而生長奈米碳管陣列，形成場發射陰極。While the carbon nanotubes emit electrons as field emitters, it is too treacherous ~= not to end the end of the tube tube along the axial tube field emission performance. On the anti-S conductive substrate, it is not conducive to nano-breaking. The dish is necessary to provide a === cathode, method, which does not damage the carbon nanotubes: Pipe field: the power substrate is substantially vertical 'to ensure the nano Carbon [Invention] A method for preparing a field emission cathode, comprising the steps of: providing a substrate, forming a conductive film layer on the surface of the substrate; forming a light absorbing layer on the conductive film layer; forming a catalyst layer in the above On the light absorbing layer; a mixed gas of a carbon source gas and a carrier gas flows through the surface of the catalyst layer; and a laser beam is focused on the substrate to grow an array of carbon nanotubes to form a field emission cathode.
相較於先前技術，所述的奈米碳管陣列的製備方 法形成有一光吸收層位於催化劑層與基底之間。該光 吸收層可有效吸收雷射能量並加熱催化劑，可削弱雷 射場強度，可在一定程度上避免雷射破壞新生長出來 的奈米碳管；同時，在反應過程中可釋放碳原子促進 奈米碳管的成核及生長，因此，所述的場發射陰極的 製備方法得到的場發射陰極中的奈米碳管陣列基本 垂直於基底，具有良好的場發射性能。 【實施方式】 以下將結合附圖對本發明作進一步的詳細說明。 1321805 請參閱圖1，本發明實施例場發射陰極的製備方法 主要包括以下幾個步驟： 步驟一：提供一基底。 本實施例中基底材料選用耐高溫材料製成。板據 不同應用’本實施例中基底材料還可分別選用透明或 不透明材料，如，當應用於半導體電子器件時可選擇 為矽、二氧化矽或金屬材料等不透明材料；當應用於 大面積平板顯示器時，優選為玻璃、可塑性有機材料 等透明材料。 / 步驟一.在上述基底表面形成一導電薄膜。 該導電薄膜可通過熱沈積、電子束沈積或濺射法 形成在上述基底表面。本實施例中，該導電薄膜材料 優選為氧化銦錫薄膜，其厚度為1〇〜1〇〇奈 為30奈米。 馒選 步驟三：在上述導電薄膜上形成一光吸收層。 本實施例中，該光吸收層的製備方法包括以下步 驟：將一含碳材料塗敷於上述基底的導電薄膜表面( 知呆護氣體環境中，將塗敷有含碳材料的基底在約9〇 分鐘内逐漸加溫_ 以上，並烘烤-段時間； 自然冷部到室溫形成吸收層於基底表面的 薄膜上。 本發明實施例中，保護氣體包括氮氣或惰性氣 體，含破材料優選為目前廣泛應用於電子產品如冷陰 極顯像管中的石墨乳材料。進—步地，該石墨乳可^ 8 過旋轉塗敷方式形成於基底表面 誦〜·轉/分（咖），優選為1500rpm。所开;^ 光吸收層的厚度為卜2〇 —烘烤的目的= 使得含碳材料中的其他材料蒸發，如將石 古 機物蒸發。 的有 步驟四L催化劑層於上述光吸收層上。 該催化劑層的形成可利用熱沈積、電子束 藏射法來完成。催化劑層的材料選用鐵，也可選用貝= 他材料，如氣化鎵、钻、鎳及其合金材料等。進^ 地’該催化劑層可通過高溫退火等方式氧化催化二 層，形成催化劑氧化物顆粒。 另，該催化劑層可通過將一催化劑溶液塗敷於光 吸收層上形成’其具H步驟包括：提供_催化劑乙醇 溶液；將該催化劑乙醇溶液塗敷於上述光吸收層表 面。 本實施例中’該催化劑乙醇溶液為將金屬确酸鹽 混合物與乙醇溶液混合形成。該金屬硝酸鹽化合物包 括硝酸鎂（Mg(N〇3)2.6H2〇)與硝酸鐵（Fe(N〇3)3.9H2〇)、 硝酸鈷（Co⑽A · 6H2〇)或硝酸鎳⑻（NO3)2 ·他〇)中任 一種或幾種組成的混合物。優選地，該催化劑乙醇溶 液為硝酸鎂與硝酸鐵組成的混合物的乙醇溶液，溶液 中硝酸鐵的含量為0. 01〜0· 5摩爾/升（M〇l/L)，確酸 錯的含重'為0.01〜0· 5Mol/L。該催化劑乙醇溶液可通 過旋轉塗敷形成於光吸收層表面，其轉速優選為約 1500rpm。所形成的催化劑層的厚度為卜100奈米。 步驟五：通入碳源氣與載氣的混合氣體流經上述 催化劑層表面。 h該碳源氣優選為廉價氣體乙炔，也可選用其他碳 ，化合物如甲燒、乙烧、乙烯等。載氣氣體優選為氬 ^，也可選用其他惰性氣體如氮氣等。本實施例中， 石反源氣與载氣可通過一氣體噴嘴直接通入到上述催 化劑層表面附近。載氣與碳源氣的通氣流量比例為 5 ·卜ίο · 1，本實施例優選為通以2〇()標準毫升/分 (seem)的氬氣與25sccm的乙炔。 乂每射光束名焦照射加熱催化劑層從而 生長奈米碳管陣列，得到場發射陰極。 。本實施例中，雷射光束可通過傳統的氬離子雷射 器或二氧化碳雷射器產生，其功率為瓦⑺，優 k為470mW。產生的雷射光束可通過一透鏡聚焦後從 正面直接照射在上述催化劑層表面，可以理解，該雷 射光束可採用垂直照射或傾斜照射聚焦於催化劑層 上另，§基底選用不透明材料時，該雷射光束也可 聚焦後照射基底的反面’由於本發明實施例基底可採 用透明材料’前射絲能量可輯透過基底傳遞 催化劑層並加熱催化劑。 反應預定時間後，由於催化劑的作用，通入到 底附近的碳源氣在-定溫度下熱解成碳單元（c=c ^ c)與氫氣。其中，氫氣會將被氧化的催化劑還原，= 單元吸附於催化劑層表面’從而生長出夺米碳管。本 實施例中’由於採用雷射作為加熱熱源，且利用光吸 收層吸收雷魏量的制，觀學Μ目㈣法反應溫 度可低於600攝氏度。 刀，令货阳戈犯燜休用雷射聚焦照射生長奈 米礙管陣列製備場發射陰極，催化劑局部溫度在較短 時間内能夠被加熱並吸收足夠的能量，㈣，碳源氣 為直接通入到被加熱的催化劑表面附近。因此，本發 明實施例可無需-密封的反應室，即可同時保證生長 奈米碳管陣列的催化劑附近達到所需的溫度及碳源 氣的濃度，且’由於碳源氣分解產生的氳氣的還原作 用’可確絲化的催化雛夠_原，並促使奈 管陣列生長。 本發明實施射形成的石墨乳層在本發明製傷卞 米碳管場發射陰極的方法有以下優點：第—由於: 墨乳層能有效吸收雷射能量並加熱催化劑，可使得該 催化劑層更容㈣到生長奈米碳管所需溫度，本實= 例中反應溫度可低於_。〇：;第二，該石墨乳層可削 弱雷射場錢’可在-絲度上料雷射破壞新生長 出來的奈米碳管；第三’該石墨乳層在反應過程中可 釋放出碳原子促進奈米碳管的成核及生長，使得生長 的奈米碳管具有良好的陣列形態。 另，當採用雷射聚焦反面照射基底製備奈米碳管 場發射陰極，可有效避免雷射光束正面照射破壞奈米 1321805 碳管陣列。且，雷射光束也不會與參與奈米碳管生長 反應的氣體進行任何直接作用，不會對氣體的性質進 行影響’進而破壞奈米碳管陣列的生長。 凊參閱圖2 ’本發明實施例依照上述方法以聚焦後 直徑範圍在50〜200微米的雷射光束垂直照射在玻璃 基底的催化劑上約30秒鐘，可得到如圖2所示的奈 米碳管場發射陰極。該場發射陰極包括一基底、一導 電薄膜作為電極層以及奈米碳管陣列作為場發射 端’其中的奈米碳管陣列為山丘形狀，且垂直於基底 生長。該奈米碳管陣列的直徑為1〇〇〜2〇〇微米，高度 為0.1〜100微米。每個奈米碳管的直徑為1〇〜3〇奈米。 請參閱圖3’本發明實施例依照上述方法在同一基 底上可按照預定圖案用雷射光束多次照射在基底的 催化劑層上，可得到如圖3所示的場發射陰極陣列。 該場發射陰極陣列包括多個場發射陰極按照預定圖 案排列於同一基底，每一個場發射陰極都包括一個奈 米碳管陣列。 不 綜上所述，本發明確已符合發明專利之要件，遂 依法提出專财請。惟，以上所述者僅為本發明之較 佳實施例’自不能以此限制本案之中請專利範圍。舉 凡熟悉本索技藝之人士援依本發明之精神所作之等 效修飾或變化，皆應涵蓋於以下申請專利_内。 【圖式簡單說明】 圖1係本發明實施例場發射陰極的製傷方法的流 12 1321805 程示意圖。 圖2係本發明實施例獲得的奈米碳管場發射陰極 的掃描電鏡照片。 圖3係本發明實施例獲得的奈米碳管場發射陰極 陣列的掃描電鏡照片。 【主要元件符號說明】 無Compared to the prior art, the carbon nanotube array is prepared by forming a light absorbing layer between the catalyst layer and the substrate. The light absorbing layer can effectively absorb the laser energy and heat the catalyst, can weaken the intensity of the laser field, and can prevent the laser from destroying the newly grown carbon nanotubes to a certain extent; at the same time, the carbon atom can be released during the reaction to promote the naphthalene The nucleation and growth of the carbon nanotubes, therefore, the nano-tube array in the field emission cathode obtained by the method for preparing the field emission cathode is substantially perpendicular to the substrate and has good field emission properties. [Embodiment] Hereinafter, the present invention will be further described in detail with reference to the accompanying drawings. 1321805 Referring to FIG. 1, a method for preparing a field emission cathode according to an embodiment of the present invention mainly includes the following steps: Step 1: Provide a substrate. In the embodiment, the base material is made of a high temperature resistant material. According to different applications, the base material in this embodiment may also be selected from transparent or opaque materials, for example, when applied to semiconductor electronic devices, opaque materials such as tantalum, cerium oxide or metal materials may be selected; In the case of a display, a transparent material such as glass or a plastic organic material is preferable. / Step 1. Form a conductive film on the surface of the substrate. The electroconductive thin film may be formed on the surface of the substrate by thermal deposition, electron beam deposition or sputtering. In this embodiment, the conductive film material is preferably an indium tin oxide film having a thickness of 1 Å to 1 Å to 30 nm. Selection Step 3: Forming a light absorbing layer on the above conductive film. In this embodiment, the method for preparing the light absorbing layer comprises the steps of: applying a carbonaceous material to the surface of the conductive film of the substrate (in a gas environment, the substrate coated with the carbonaceous material is about 9) Gradually warming _ above, and baking for a period of time; the natural cold portion to room temperature forms an absorption layer on the film on the surface of the substrate. In the embodiment of the invention, the shielding gas includes nitrogen or an inert gas, and the broken material is preferably used. It is a graphite milk material which is widely used in electronic products such as cold cathode picture tubes. Further, the graphite milk can be formed on the surface of the substrate by spin coating, 转 rpm rpm, preferably 1500 rpm. The thickness of the light absorbing layer is 〇2〇—the purpose of baking = to evaporate other materials in the carbonaceous material, such as the evaporation of the stone ancient matter. There is a step 4 L catalyst layer on the above light absorbing layer. The formation of the catalyst layer can be completed by thermal deposition and electron beam storage. The material of the catalyst layer is iron, and other materials such as gallium carbide, diamond, nickel and alloy materials thereof can also be used. ^ The catalyst layer can be oxidized to catalyze two layers by high temperature annealing or the like to form catalyst oxide particles. Alternatively, the catalyst layer can be formed by applying a catalyst solution to the light absorbing layer. a catalyst ethanol solution; the catalyst ethanol solution is applied to the surface of the light absorbing layer. In the present embodiment, the catalyst ethanol solution is formed by mixing a metal acid salt mixture with an ethanol solution. The metal nitrate compound includes magnesium nitrate (Mg). (N〇3) 2.6H2〇) with or with iron nitrate (Fe(N〇3)3.9H2〇), cobalt nitrate (Co(10)A · 6H2〇) or nickel nitrate (8) (NO3) 2 · other) a mixture of components. 01〜0· 5摩尔/升(M〇l/L), the acid-containing content is preferably 0. 01~0·5 mol/L (M〇l/L), the acid solution of the catalyst is a mixture of magnesium nitrate and ferric nitrate. The weight 'is 0.01~0·5Mol/L. The catalyst ethanol solution can be formed on the surface of the light absorbing layer by spin coating, and the rotation speed thereof is preferably about 1,500 rpm. The thickness of the formed catalyst layer was 100 nm. Step 5: a mixed gas of a carbon source gas and a carrier gas is passed through the surface of the catalyst layer. h The carbon source gas is preferably an inexpensive gas acetylene, and other carbons such as methyl ketone, ethylene bromide, ethylene, etc. may also be used. The carrier gas is preferably argon, and other inert gases such as nitrogen may also be used. In this embodiment, the stone source gas and the carrier gas can be directly introduced into the vicinity of the surface of the catalyst layer through a gas nozzle. The ratio of the aeration flow rate of the carrier gas to the carbon source gas is 5 · ίο · 1, and this embodiment is preferably argon gas of 2 〇 () standard cc / min (seem) and acetylene of 25 sccm.乂 Each beam of light is irradiated with a heated catalyst layer to grow a carbon nanotube array to obtain a field emission cathode. . In this embodiment, the laser beam can be generated by a conventional argon ion laser or a carbon dioxide laser having a power of watt (7) and an excellent k of 470 mW. The generated laser beam can be directly focused on the surface of the catalyst layer from the front surface after being focused by a lens. It can be understood that the laser beam can be focused on the catalyst layer by vertical illumination or oblique illumination. When the substrate is made of opaque material, The laser beam can also be focused to illuminate the opposite side of the substrate. 'Because the substrate of the present invention can employ a transparent material, the front fiber energy can pass through the substrate to transfer the catalyst layer and heat the catalyst. After a predetermined period of reaction, the carbon source gas introduced into the vicinity of the bottom is pyrolyzed into a carbon unit (c = c ^ c) and hydrogen at a constant temperature due to the action of the catalyst. Among them, hydrogen will reduce the oxidized catalyst, and the unit will adsorb on the surface of the catalyst layer to grow the carbon nanotubes. In the present embodiment, since the laser is used as the heating heat source and the light absorption layer is used to absorb the amount of Ray Wei, the reaction temperature of the observation method (4) may be lower than 600 degrees Celsius. Knife, so that Yang Yang Ge smashed the laser to focus on the growth of the nanometer obstructed array to prepare the field emission cathode, the local temperature of the catalyst can be heated and absorb enough energy in a short time, (4), the carbon source gas is direct Enter into the vicinity of the heated catalyst surface. Therefore, the embodiment of the present invention can simultaneously ensure the desired temperature and the concentration of the carbon source gas in the vicinity of the catalyst for growing the carbon nanotube array without the -sealed reaction chamber, and the helium gas generated by the decomposition of the carbon source gas. The reduction of the 'simplified catalyzed stimuli is enough to promote the growth of the tube array. The method for forming a graphite emulsion layer formed by the present invention has the following advantages in the method for injecting a cathode of a carbon nanotube field in the present invention: First, since: the ink layer can effectively absorb the laser energy and heat the catalyst, the catalyst layer can be made more (4) The temperature required to grow the carbon nanotubes, in this case, the reaction temperature can be lower than _. 〇: Second, the graphite emulsion layer can weaken the laser field money, which can destroy the newly grown carbon nanotubes in the -filament loading laser; the third 'the graphite emulsion layer can release carbon during the reaction process. The atom promotes the nucleation and growth of the carbon nanotubes, so that the growing carbon nanotubes have a good array morphology. In addition, when the nano-carbon tube field emission cathode is prepared by irradiating the substrate with the laser focusing back surface, the front side of the laser beam can be effectively prevented from damaging the nano 1321805 carbon tube array. Moreover, the laser beam does not directly interact with the gas involved in the growth reaction of the carbon nanotubes, and does not affect the properties of the gas, thereby destroying the growth of the carbon nanotube array. Referring to Fig. 2, in the embodiment of the present invention, a laser beam having a diameter ranging from 50 to 200 μm after focusing is vertically irradiated on a catalyst of a glass substrate for about 30 seconds according to the above method, thereby obtaining a nanocarbon as shown in Fig. 2. The tube field emits a cathode. The field emission cathode includes a substrate, a conductive film as an electrode layer, and a carbon nanotube array as a field emission terminal. The carbon nanotube array is in the shape of a hill and grows perpendicular to the substrate. The carbon nanotube array has a diameter of 1 〇〇 2 2 μm and a height of 0.1 to 100 μm. Each carbon nanotube has a diameter of 1 〇 to 3 〇 nanometer. Referring to Fig. 3', in the embodiment of the present invention, a field emission cathode beam array as shown in Fig. 3 can be obtained by irradiating a plurality of laser beams on a catalyst layer in a predetermined pattern on a same substrate in accordance with the above method. The field emission cathode array includes a plurality of field emission cathodes arranged in a predetermined pattern on the same substrate, each field emission cathode including an array of carbon nanotubes. In summary, the present invention has indeed met the requirements of the invention patent, and 提出 legally filed a special account. However, the above description is only a preferred embodiment of the present invention, which is not intended to limit the scope of the patent application in this case. Any modification or variation made by a person familiar with the skill of the present invention in accordance with the spirit of the present invention shall be covered by the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing the flow of a method for injuring a field emission cathode according to an embodiment of the present invention. Fig. 2 is a scanning electron micrograph of a carbon nanotube field emission cathode obtained in an embodiment of the present invention. Figure 3 is a scanning electron micrograph of a carbon nanotube field emission cathode array obtained in an embodiment of the present invention. [Main component symbol description] None
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