1321806 九、發明說明： 【發明所屬之技術領域】 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 性能’且其具有幾乎接近理論極限的尖端表面積（尖端表面 積越小，其局部電場越集中），故’奈米碳管係已知最好的 場發射材料，其具有極低場發射電壓，可傳輸極大電流密 度，且電流極穩定’因而非常適合做場發射顯示器的發射 組件。 x 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 用於場發射顯示器的方式有：將含有奈米碳管的導電装料 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。在此方法中反= 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’奈求礙管在聚料中發生·彎曲，相互交織，不易形 f垂直於導電基板的奈米碳管，為形成性能良好的發歡 端，需對奈米碳管_進行後續處理，即將—層轉剝離， 從而使奈米碳管從聚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 队在導電基板上’相對導電基板垂直的奈米碳管較$。然 1321806 :射m發射體’係從奈米破管的一端沿轴向 料發雜_發;祕^在導電基板上不利於奈米碳 ==:::電基板基本垂直’從，- 【發明内容】1321806 IX. Description of the Invention: [Technical Field] The present invention relates to a method for preparing a field emission cathode, and more particularly to a method for preparing a field emission cathode based on a carbon nanotube. [Prior Art] Carbon nanotubes are a new type of carbon material with extremely excellent electrical conductivity' and have a tip surface area close to the theoretical limit (the smaller the tip surface area, the more concentrated the local electric field), so 'nano carbon The tube system is known to have the best field emission material, which has a very low field emission voltage, can transmit a very large current density, and is extremely stable in current', making it ideal for use as a transmitting component of a field emission display. x The carbon nanotubes used for the emitting elements are generally carbon nanotubes grown by arc discharge or chemical vapor deposition (CVD). The method of applying a carbon nanotube to a field emission display is to print a conductive charge or an organic adhesive containing a carbon nanotube into a pattern, and the carbon nanotube can be exposed from the burying of the slurry through subsequent processing. Become an emitter. In this method, the conductive paste having the carbon nanotubes is coated on the conductive substrate by printing with a thick film steel plate, which means that the tube is generated and bent in the polymer, and is interwoven, and the shape f is not perpendicular to the conductive substrate. The carbon nanotubes, in order to form a good performance of the hair ends, need to be processed on the carbon nanotubes, that is, the layer is peeled off, so that the carbon nanotubes are exposed from the burial of the aggregate and become the emission. However, stripping this slurry layer is very damaging to the carbon nanotubes. In the carbon nanotube layer prepared by the above method, the carbon nanotubes on the conductive substrate are relatively smaller than the carbon nanotubes perpendicular to the conductive substrate. However, 1321806: the emitter of the emitter is emitted from the end of the tube of the nano tube in the axial direction; the secret ^ is not conducive to the nano carbon on the conductive substrate ==::: the substrate is substantially vertical 'from, - SUMMARY OF INVENTION
-種場發射陰極的製#方法，其包括以下步驟： 提供一基底；在上述基底表面形成-導電薄膜層；在 導電薄膜層上形成—含碳的催化騎；通人碳i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。 x 相較於先前技術，所述的場發射陰極的製備方法 中採用含碳的催化劑層用於雷射輔助化學氣相沈積 生長奈采碳官P車列。該催化劑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，由該場 ，射陰極的製備方法得到的場發射陰極中的奈=碳 官陣列垂直於基底，因此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。 請參閱圖1’本發明實施例場發射陰極的製備方法 7 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南溫材料製成。根據 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。 步驟二：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、電子束沈積或藏射法 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10〜100奈米，優選 為30奈米。 步驟三：在上述導電薄膜上形成一含碳的催化劑 〇 本實施例中，該含碳的催化劑層的製備方法包括 以下步驟：提供一種分散劑與一種含碳物質的混合 物，並與一溶劑混合形成溶液；將該溶液進行超聲波 分散處理；在該分散後的溶液中加入金屬硝酸鹽混合 物溶解得到一催化劑溶液；將該催化劑溶液均勻塗敷 於上述導電薄膜上；烘烤從而形成一含碳的催化劑 層。 其中，該含碳物質包括碳黑或石墨等含碳材料。 該分散劑用於將含碳物質岣勻分散，優選為十二烷基 1321806 - 苯橫酸納（Sodium Dodecyl Benzene Sulfonate, . SDBS)。溶劑可選擇為乙醇溶液或水。該分散劑與含 碳物質的品質比為1:2〜；hlO,本實施例優選為將 (M00毫克的十二烷基苯磺酸鈉與100〜500毫克的碳 黑混合物與乙醇溶液混合形成溶液。 該金屬硝酸鹽化合物包括硝酸鎂（Mg(N〇3)2 · 6H2O) 與石肖酸鐵（Fe(N〇3)3‘9H2〇)、墙酸钻（Co(N〇3)2,6H2〇)或 石肖酸鎳（Ni (N〇3)2 · 6H2O)中任一種或幾種組成的混合 鲁 物。本實施例優選為將硝酸鐵（Fe(N〇3)3· 9H2〇)與蹲酸 鎂（Mg(N〇3)r6H2〇)加入到溶液中形成催化劑溶液，該 催化劑溶液中含有0. 01〜0. 5摩爾（Mol/L)的硝酸鎂與 0. 01〜0. 5Mol/L的瑣酸鐵。 烘烤的溫度為60〜100°C。烘烤的作用為將催化劑 溶液中的溶劑蒸發從而形成一含碳催化劑層。 本實施例中，該含碳的催化劑層的厚度為10〜100 微米。催化劑溶液塗敷於基底表面可採用旋轉塗敷的 ® 方式，其轉速為1000〜5000轉/分鐘（rpm)，優選為 1500rpm 。 ' 步驟四：通入碳源氣與載氣的混合氣體流經上述 催化劑層表面。 該碳源氣優選為廉價氣體乙炔，也可選用其他碳 氫化合物如甲烷、乙烷、乙烯等。載氣氣體優選為氬 氣，也可選用其他惰性氣體如氮氣等。本實施例中， 碳源氣與載氣可通過一氣體噴嘴直接通入到上述催 9 1321806 化劑層表面附近。載氣與碳源氣的通氣流量比例為 5 : 1〜10 : 1，本實施例優選為通以200標準毫升/分 (seem)的氬氣與25sccm的乙炔。 步驟四：以雷射光束聚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，其功率為〇〜5瓦（W)，優 選為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’當基底材料為透明材料時，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採用 透明材料，該雷射光束能量可迅速透過基底傳遞到催 化劑層並加熱催化劑。 反應預定時間後，由於催化劑的作用，通入到基 底附近的碳源氣在一定溫度下熱解成碳單元（c=c或 C)與氫氣。其中，氫氣會將被氧化的催化劑還原，碳 單元吸附於催化劑層表面，從而生長出奈米碳管。本 實施例中，由於採用雷射作為加熱熱源，且利用含碳 催化劑層吸收雷射能量的作用’該化學氣相沈積法反 應溫度可低於600攝氏度。 本發明實施例採用上述含碳的催化劑層有以下優 點：第一，該含碳催化劑層可有效吸收雷射能量並加 熱催化劑，以使得該催化劑層更容易達到生長奈米碳 10 1321806 管所需溫度，第二，該含碳催化劑層可削弱雷射場強 度，可在一定程度上避免雷射正面照射破壞新生長出 來的奈米碳管；第三，該含碳催化劑層在反應過程中 可釋放碳原子促進奈米碳管的成核及生長。 另，當採用雷射聚焦反面照射基底生長奈米碳管 陣列，可有效避免雷射光束正面照射破壞奈米碳管陣 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。 另，由於本發明實施例採用雷射聚焦照射生長奈 米碳管陣列，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，同時，碳源氣為直接通入到被 加熱的催化劑表面附近。因此，本發明實施例無需一 密封的反應室，即可同時保證生長奈米碳管陣列的催 化知彳附近達到所需的溫度及碳源氣的密度，且，由於 奴源氣分解產生的氫氣的還原作用，可確保氧化的催 化劑能夠被還原，並促使奈米碳管陣列生長。 請參閱圖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破璃 基底的催化劑上約5秒鐘，可得到如圖2所示的齐米 碳管場發射陰極。該場發射陰極包括—基底、一導^ 薄膜作為電極層以及奈米碳管陣列作為場發射端，盆 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50〜80微米，高度為烈 11 1321806 微米。每個奈米碳管的直徑為40〜80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。 綜上所述，本發明確已符合發明專利之要件，遂 # 依法提出專利申請。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申請專利範圍。舉 凡熟悉本案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範圍内。 【圖式簡單說明】 圖1係本發明實施例場發射陰極的製備方法的流 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】 益 #»*> 12a method for producing a field emission cathode, comprising the steps of: providing a substrate; forming a conductive film layer on the surface of the substrate; forming a carbon-containing catalytic ride on the conductive film layer; and conducting carbon and gas The mixed gas flows through the surface of the catalyst layer; and the substrate is irradiated with a laser beam to grow the carbon nanotube array to form a field emission cathode. x Compared to the prior art, the field emission cathode is prepared by using a carbon-containing catalyst layer for laser assisted chemical vapor deposition growth. The catalyst layer can effectively absorb the laser energy and heat the catalyst, which can weaken the intensity of the laser field, and can prevent the laser from destroying the newly grown carbon nanotubes to some extent; at the same time, the field is prepared by the method of preparing the cathode. The n=carbon officer array in the field emission cathode is perpendicular to the substrate and therefore has good field emission properties. [Embodiment] The present invention will be further described in detail below with reference to the accompanying drawings. Referring to FIG. 1 ′, a method for preparing a field emission cathode according to an embodiment of the present invention includes the following steps: Step 1: Provide a substrate. In this embodiment, the base material is made of a material resistant to southermost materials. 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; when applied to large-area flat panel displays In the case, a transparent material such as glass or a plastic organic material is preferable. Step 2: forming 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 deposition. In the present embodiment, the conductive film material is preferably an indium tin oxide film having a thickness of 10 to 100 nm, preferably 30 nm. Step 3: forming a carbon-containing catalyst on the conductive film. In the present embodiment, the method for preparing the carbon-containing catalyst layer comprises the steps of: providing a mixture of a dispersing agent and a carbonaceous material, and mixing with a solvent. Forming a solution; subjecting the solution to ultrasonic dispersion treatment; adding a metal nitrate mixture to dissolve the solution to obtain a catalyst solution; uniformly coating the catalyst solution on the conductive film; baking to form a carbon-containing Catalyst layer. Wherein, the carbonaceous material comprises a carbonaceous material such as carbon black or graphite. The dispersant is used to uniformly disperse the carbonaceous material, preferably dodecyl 1321806 - Sodium Dodecyl Benzene Sulfonate (SDBS). The solvent can be selected from an ethanol solution or water. The mass ratio of the dispersing agent to the carbonaceous material is 1:2~; hlO. In this embodiment, it is preferred to mix (M00 mg of sodium dodecylbenzenesulfonate with 100 to 500 mg of carbon black mixture and ethanol solution). The metal nitrate compound includes magnesium nitrate (Mg(N〇3)2 · 6H2O) and iron oxalate (Fe(N〇3)3'9H2〇), wall acid drill (Co(N〇3)2 , 6H2〇) or a mixture of nickel or nickel tartaric acid (Ni(N〇3)2 · 6H2O), or a mixture of several components. This embodiment is preferably iron nitrate (Fe(N〇3)3·9H2 5〜(Mol/L) of magnesium nitrate with 0. 01~ 0. 5 Mol / L of iron succinate. The baking temperature is 60 to 100 ° C. The baking function is to evaporate the solvent in the catalyst solution to form a carbon-containing catalyst layer. In this embodiment, the carbon-containing catalyst The catalyst layer has a thickness of 10 to 100 μm. The catalyst solution is applied to the surface of the substrate by a spin coating method, and the rotation speed is 1000 to 5000 rpm, preferably 1500 rpm. The mixed gas of the carbon source gas and the carrier gas flows through the surface of the catalyst layer. The carbon source gas is preferably an inexpensive gas acetylene, and other hydrocarbons such as methane, ethane, ethylene, etc. may be used. The carrier gas is preferably argon. Alternatively, other inert gases such as nitrogen may be used. In this embodiment, the carbon source gas and the carrier gas may be directly introduced into the vicinity of the surface of the catalyst layer through a gas nozzle. The aeration flow rate of the carrier gas and the carbon source gas The ratio is 5:1~10: 1, and the embodiment is preferably argon gas with 200 standard milliliters/min (seem) and acetylene of 25 sccm. Step 4: focusing the laser beam with the laser beam to grow the nanocarbon The tube array is used to obtain a field emission cathode. In this embodiment, the laser beam can be generated by a conventional argon ion laser or carbon dioxide laser having a power of 〇 5 watts (W), preferably 470 mW. The beam of light 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. In the case of a transparent material, the laser beam can also be focused to illuminate the opposite side of the substrate. Since the substrate of the embodiment of the present invention uses a transparent material, the laser beam energy can be quickly transmitted through the substrate to the catalyst layer and heat the catalyst. Due to the action of the catalyst, the carbon source gas introduced into the vicinity of the substrate is pyrolyzed into a carbon unit (c=c or C) and hydrogen at a certain temperature, wherein the hydrogen gas will reduce the oxidized catalyst, and the carbon unit adsorbs to the catalyst layer. The surface, thereby growing a carbon nanotube. In this embodiment, since the laser is used as a heating heat source, and the effect of absorbing the laser energy by the carbon-containing catalyst layer is employed, the reaction temperature of the chemical vapor deposition method may be lower than 600 degrees Celsius. The embodiment of the present invention adopts the above carbon-containing catalyst layer to have the following advantages: First, the carbon-containing catalyst layer can effectively absorb the laser energy and heat the catalyst, so that the catalyst layer is more easily required to grow the nanocarbon 10 1321806 tube. Temperature, secondly, the carbon-containing catalyst layer can weaken the intensity of the laser field, and can prevent the frontal irradiation of the laser from destroying the newly grown carbon nanotubes to some extent; third, the carbon-containing catalyst layer can be released during the reaction. Carbon atoms promote the nucleation and growth of carbon nanotubes. In addition, when the substrate is used to irradiate the substrate to grow the carbon nanotube array, the front side of the laser beam can be effectively prevented from damaging the carbon nanotube 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. In addition, since the embodiment of the present invention uses the laser focused irradiation to grow the carbon nanotube array, the local temperature of the catalyst can be heated and absorb sufficient energy in a short time, and at the same time, the carbon source gas is directly passed to the heated catalyst. Near the surface. Therefore, the embodiment of the present invention does not require a sealed reaction chamber, and can simultaneously ensure that the temperature of the carbon nanotube gas is reached near the catalytic know-how of the growth carbon nanotube array, and the hydrogen gas generated by the decomposition of the slave gas. The reduction ensures that the oxidized catalyst can be reduced and promotes 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 micrometers after focusing is vertically irradiated on the catalyst of the glass substrate for about 5 seconds according to the above method, thereby obtaining a meter as shown in FIG. The carbon tube field emits a cathode. The field emission cathode comprises a substrate, a thin film as an electrode layer and a carbon nanotube array as a field emission end, wherein the carbon nanotube array in the basin is in the shape of a hill, and the carbon nanotube array is grown perpendicular to the substrate. The diameter is 50~80 microns and the height is 11 1321806 microns. Each carbon nanotube has a diameter of 40 to 80 nm. Referring to Fig. 3, an embodiment of the present invention can irradiate a plurality of laser beams on a catalyst layer of a substrate in a predetermined pattern on a same substrate according to the above method, and a field emission cathode array as shown in Fig. 3 can be obtained. 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 # patent application is filed according to law. However, the above is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application in this case. Equivalent modifications or variations made by those skilled in the art to the spirit of the invention are intended to be included within the scope of the following claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic flow chart showing a method of preparing 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 an array of carbon nanotube field emission cathodes obtained in an embodiment of the present invention. [Main component symbol description] Benefit #»*> 12