經濟部中央橾率局員工消費合作杜印製 A7 B7 五、發明説明（1 ) 本發明係有關於一種氮化物材料的蝕刻方法，特別 係有關於一種利用紫外光燈源以增益的氮化物材料的濕 式蝕刻方法。 運用三五族半導體製作發光元件乃屬於為人熟知的 先前技術，在製造元件的過程中，同樣地需要使用到一 般標準半導體製程中所使用的磊晶、光罩製版、蝕刻、 擴散或鍍膜等步驟。然而，由於半導體材料上的差異， 同時卻也導致了前述各種步驟在實施上有所不同。特別 是在蝕刻的步驟中，材料的差異所造成的蝕刻方式之不 同更是明顯，舉例而言，M.N. Rubert et al.在”J. Electrochem. Soc.” 138, pp. 1174 - 1185 (1991)中所揭露的 光電化學蚀刻（Photoelectrochemical, PEC)技術，其配合 可見光和化學藥劑的作用，便曾廣泛地被應用在低能帶 三五族半導體，如珅化鎵、填化銦等的餘刻上。 但是將此種光電化學蝕刻技術運用在用以製作寬能 帶藍綠光元件的氮化鎵半導體材料的蝕刻上，在先前技 術中目前僅有 M.S. Minsky et al.的’’Room- temperature photoenhanced wet etching of GaNs,. Appl. Phys. Lett. 68, pp. 1531-1533 (1996)，其利用功率強度為 570 mW/cm2 的 325nm之He_Cd雷射作用在無外加偏壓狀況下的蝕刻。 以及 H. Lu et al.的”Photoassisted anodic etching of GaN”，J Electrochem. Soc. 144, L8-L11(1997)，其使用功率強度為 60mW/cm2 之 365nm 和 150mW/cm2 之 405nm 的汞燈作用 在有外加偏壓下的#刻。以及Y〇utseyetal·的’’Broad- 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） . - --------------IT----------J t --- (請先«讀背面之注意事項再填寫本頁) A7 ' B7 五、發明説明（2 ) area photoelectroch. etching of GaN55, Elec. Lett. 33, 245-246(1997)，其使用未經濾光的汞燈（功率強度分別為 320nm 時的 6.4mW/cm2, 365nm 時的 7.4mW/cm2,及 405nm 時的13.2mW/cm2)多頻光源，作甩在無外加偏壓的情況 下。 經濟部中央標準局員工消費合作社印製 (請先«讀背面之注意事項再填寫本頁) 在上述先前技術中，Minskey et al.的缺點在於He-Cd雷_光點對氮化鎵的有效作用面積太小，僅有1mm2， 並且入射光透過燒杯管壁之後的模態分佈不是空間的均 勻函數，這些缺點會造成在發光元件製程上，經濟效益 與良率的困擾。至於Lu et al.，其所使用之入射光波長 (365nm 及 405nm)小於氮化鎵的能帶吸收 (3.4eV，364.7nm)，在此情況下，外加偏壓的效果其實就 類似於電化學中的陽極電解，而使用365nm或405nm汞 燈的作用，也不過只是在於造成加熱效應。至於Youtsey et al.的實驗架構，在製程中具有蝕刻深度不均勻的問 題，例如以尺寸為0 · 5 X1 cm2的樣品而言，其钮刻深度的 變異在雜質濃度為l〇18cm_3的情形下，已有20〜30%，而 在1016cm_3下，更高達80%。且前述參項先前技術都具 有下述缺點，即在上述的照光波長和實驗條件下，蝕刻 平面的平整度（roughness)約為100nm，這對於製作短波 長小於45Onm的雷射二極體的鏡面（facet)而言，會產生 過大的光學損耗，因而會影響元件的發光效率。 有鑑於此，為了解決上述先前技術中的問題與缺 點，本發明乃提出一種氮化物材料的蝕刻方法，其主要 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 五、發明説明（3 ) 係有關於利用波長為254nm的單 化紹銦鎵的濕^刻技術。 ’、7以增益氮 本發明之-特點在於可有效控制㈣速率，並 ，平面之平整度，和敍刻深度之均句度： 大尺寸面積(2英相上的晶圓）的製程技術。 製乍 .本.發明之另-特點在於可即時監控(in-situ monitoring)蝕刻深度。 本發明之再—特點在於可㈣刻技術與元件製程技 術積體整合化。 表孜 本發明主要係在進行氮化物敍刻時，利用波長為 •的深紫外線照射氮化物表面，使產生熱電子電洞 對’電洞參錢化鎵的氧化難，以生成氧化物，並溶 解於餘刻液中。電子則經由金屬導線與電解液中的離子 形成完整的迴路。利用此種方式，除了可維持㈣表面 时整度外，更可藉由量職刻電流，而對仙深度進 仃：時監控。同時，將此方法應用於工業量產上，也具 有谷易操作，低維護成本及高良率等優點。 為了更進__步增進對本發明之架構、方法及特點的 瞭解’下域配合附圖說明本發明之實施例，其中： 第1圖係繪示運用於本發明中之—夾持照明裝置的 立體圖； 、第2圖係繪示本發明用以提供照射氮化物材料之光 源的夾持照明裝置之前視圖； 第3圖係繪示用以實施本發明之氮化物材料的蝕刻The Consumer Cooperation of the Central Bureau of Economic Affairs of the Ministry of Economic Affairs of the People's Republic of China Du printed A7 B7 5. Description of the Invention (1) The present invention relates to an etching method for a nitride material, and particularly relates to a nitride material using a UV light source for gain Wet etching method. The use of three or five semiconductors to make light-emitting devices is a well-known prior technology. In the process of manufacturing devices, it is also necessary to use epitaxy, photomasking, etching, diffusion, or coating used in general standard semiconductor processes. step. However, due to the differences in semiconductor materials, it also results in different implementations of the foregoing steps. Especially in the etching step, the differences in the etching methods caused by the differences in materials are more obvious. For example, MN Rubert et al. In "J. Electrochem. Soc." 138, pp. 1174-1185 (1991) The photoelectrochemical (PEC) technology disclosed in the paper, combined with the action of visible light and chemical agents, has been widely used in the low-band semiconductors such as gallium halide and indium-filled. . However, this photoelectrochemical etching technology is applied to the etching of gallium nitride semiconductor materials used to make wide-band blue-green light elements. Currently, only `` Room-temperature photoenhanced wet '' by MS Minsky et al. Etching of GaNs ,. Appl. Phys. Lett. 68, pp. 1531-1533 (1996), which utilizes a 325 nm He_Cd laser with a power intensity of 570 mW / cm2 to etch without external bias. And "Photoassisted anodic etching of GaN" by H. Lu et al., J Electrochem. Soc. 144, L8-L11 (1997), which uses a mercury lamp with a power intensity of 365nm at 60mW / cm2 and 405nm at 150mW / cm2 # 刻 Under External Bias. And "Broad-Youtseyetal ·" This paper size applies to China National Standard (CNS) A4 specification (210X297 mm).--------------- IT ------ ---- J t --- (please «read the precautions on the reverse side before filling out this page) A7 'B7 V. Description of the invention (2) area photoelectroch. Etching of GaN55, Elec. Lett. 33, 245-246 ( 1997), which uses unfiltered mercury lamps (6.4mW / cm2 at 320nm, 7.4mW / cm2 at 365nm, and 13.2mW / cm2 at 405nm) multi-frequency light sources. In the case of external bias. Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs (please «read the precautions on the back before filling this page) In the above-mentioned prior art, the disadvantage of Minskey et al. Is that He-Cd thunder_light spot is effective for gallium nitride The active area is too small, only 1mm2, and the modal distribution of incident light after passing through the beaker tube wall is not a uniform function of space. These shortcomings will cause problems in the economic efficiency and yield of the light-emitting element process. As for Lu et al., The wavelength of incident light (365nm and 405nm) used is less than the band absorption (3.4eV, 364.7nm) of gallium nitride. In this case, the effect of the applied bias voltage is actually similar to electrochemical In the anode electrolysis, the use of a 365nm or 405nm mercury lamp is only for the heating effect. As for the experimental structure of Youtsey et al., There is a problem of uneven etching depth in the process. For example, for a sample with a size of 0.5 x 1 cm2, the variation in the button depth is in the case of an impurity concentration of 1018 cm_3. , Has been 20 ~ 30%, and at 1016cm_3, it is as high as 80%. In addition, the foregoing prior technologies have the following disadvantages: under the above-mentioned illumination wavelength and experimental conditions, the roughness of the etching plane is about 100 nm, which is useful for making a laser diode with a short wavelength of less than 45 nm. In terms of facet, excessive optical loss will be generated, which will affect the luminous efficiency of the device. In view of this, in order to solve the above-mentioned problems and disadvantages of the prior art, the present invention proposes a method for etching nitride materials, the main paper size of which is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) 5. Description of the invention (3) The wet engraving technology using singular indium gallium with a wavelength of 254 nm. ', 7 to gain nitrogen. The characteristics of the present invention are that it can effectively control the radon rate, and the flatness of the plane, and the average depth of the engraving depth: a large-scale area (wafers on 2 inches) process technology. Another feature of the invention is that it can in-situ monitor the etching depth. Another feature of the present invention is the integration of engravable technology and component manufacturing technology. The present invention mainly relates to the use of deep ultraviolet rays with a wavelength of ‧ to irradiate the nitride surface when performing nitride engraving to make it difficult to generate a hot electron hole to oxidize gallium into the hole to generate an oxide, and Dissolved in the remaining solution. The electrons form a complete circuit with the ions in the electrolyte through the metal wire. In this way, in addition to maintaining the surface time integrity of the radon, it is also possible to monitor the depth of the immortal by measuring the current at the moment. At the same time, applying this method to industrial mass production also has the advantages of easy operation, low maintenance cost, and high yield. In order to further advance the understanding of the architecture, methods, and features of the present invention, the embodiment of the present invention will be described with reference to the accompanying drawings, in which: FIG. 1 is a diagram showing the application of the present invention- 3D view; FIG. 2 is a front view of a clamping lighting device for providing a light source for irradiating a nitride material according to the present invention; FIG. 3 is a view showing etching of a nitride material for implementing the present invention
本紙張尺度適用中國國家標^YcNS) A4規格（21〇χ▲釐) 經濟部中央標準局員工消費合作社印製 五、發明説明（4 ) 方法之裝置的架構圖式； 第4圖係繪示運用本 率與PH酸驗值關係的圖式^之電解㈣液，其蚀刻速 第5圖係繪示本發明中 斑钻办丨被M y P時監控光電流之電流密度This paper size applies to the Chinese national standard ^ YcNS) A4 specification (21〇χ ▲ ▼) Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs. 5. The description of the invention (4) The structure of the device; Figure 4 is a drawing Using the electrolytic solution of the graph ^ of the relationship between the rate and the pH value, the etching rate is shown in FIG. 5 which shows the current density of the photocurrent monitored by the spot diamond office in the present invention when it is subjected to M y P
興蝕刻時間關係的圖式。 π X 附件係顯示運用本發明 電子顯微鏡照片。 對於氮化鎵蟲晶片钱刻後的 參考標號說明 絕緣基座10 ;腔柱12 ;透 思九槽14 ;夾具16 ;汞燈20 ; 電源供應器25 ;氣化物好把·>Λ 虱化物材枓30 ;金屬導線40 ;電流計 5〇 ;蝕刻槽60。 實施例之說明 在本發明之氮化物材料的_方法中，為了在進行 氮化物材料的蝕刻時’能固定氮化物材料，同時提供照 射氮化物材料的光源，本發明使用了如第i圖所示之夹 持照明裝置’其包括—絕緣基座1G，在該基座1〇中具 有-腔柱12 ’用以設置光源；—透光槽14，形成於該 基座10表面，用以使設置於前述腔柱12中的光源所產 生的光可以射出至基座1〇外部；複數個夹具16，形成 於前述透光槽14兩側，用以夾住氮化物材料。 前述基座10為了要能在蝕刻的過程中不被侵蝕，可 採用鐵弗龍作為材料。至於基座中的腔柱12則可為 一石英管。前述光源發出之光線可經由石英管與透光槽 照射至外界。且所使用的光源波長（頻率）須滿足光的能量 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） —l·----------οι 裝 IΓ I: --I (諳先-M讀背面之注意事項再填寫本頁) 訂 經濟部中央標準局員工消費合作社印製 A7 B7 五、發明説明（5) ~— (hv)大於氮化物材料之導電帶與價電帶間的能帶（£〇。其 中，h是普朗克（Planck)常數，v是光頻率。藉以使氮化 物材料中的電子可自價電帶被激發至導電帶，而形成熱 自由電子，以便在蝕刻槽中形成通路。 請參閱第2圖 > 其繪示第！圖所示之夾持照明裝置 的前視圖，同時在前述基座10之腔柱12中，根據本實 施例，設置了可發出波長為254nm深紫外光的汞燈2〇， 而如氮化鎵、氮化鋁銦鎵等的氮化物材料3〇則可藉由複 數個夾具16夾持，固定於基座1〇上，並且氮化物材料 30之一面面對著前述透光槽14，因此汞燈所發出的深紫 外光可經由前述透光槽14而照射至氮化物材料3〇上β 另外，電源供應器25則是用來提供汞燈2〇發光所需之 電源。 請參閱第3圖’其緣示用以實現本發明之氮化物材 料的蚀刻方法之裝置架構，其包括：一蝕刻槽6〇，裝有 電解餘刻液；第2圖所示之夾持照明裝置1 〇，内部設置 有汞燈20，部分浸泡於電解蝕刻液中，同時氮化物材料 3〇亦完全浸泡於電解蝕刻液中；一金屬導線4〇，部分浸 泡於電解蝕刻液中，同時經由一電流計5〇電性連接至氮 化物材料30上。 利用第3圖所示之裝置，本發明之氮化物材料的儀刻 方法係包括下列步驟：⑴將氮化物材料30設置於夾持照 明裝置10上；（ii)將夾持照明裝置10及氮化物材料30均 浸泡於電解蝕刻液中；（iii)利用汞燈20發出波長為254nm 本紙張尺度適财酬家標率（CNS ) A4%格（210X297公釐） I.--------ΟΊI-I - -:, (請先询讀背面之注意事項再填寫本頁) -訂· i J. A7 B7 五、發明説明（6 ) 的深紫外光，照射氮化物材料30 ; (iv)利用電流計50監 控蝕刻電流（亦即迴路電流），藉以即時控制蝕刻深度。 在上述實施例中，發出波長為254nm深紫外光的汞 燈，其功率強度僅約為l〇mW/cm2。遠低於先前技術的數 百甚至千個mW/cm2。 經濟部中央標準局員工消費合作社印製 (請先閙讀背面之注意事項再镇寫本頁) 對於本發明之上述實施例，可進行如下之修改，而 得到另一個不同的實施例。亦即，若使用不會吸收紫外 光的材質，例如利用石英做為蝕刻槽，則汞燈可不必置 於夾持照明裝置中，而可置於蝕刻槽外部，只要實施時 能避免紫外光對触刻液的活化（activation)以及吸收 (absorption)效應。另外，前述采燈的最短發光波長為 254nm，但本發明之光源並不限定在汞燈，其他發光波 長更短的裝置，亦可達成本發明之目的，例如準分子雷 射光源（KrF248nm、ArF193nm、'F2157nm excimer laser) 或是YAG雷射（1064nm)的四倍頻以上的轉換輸出或D2 氘燈（deuterium lamp)等。至於夾持照明裝置，由於無需 設置光源，在本實施例中，亦可加以簡化，只要可固定 氮化物材料，又不會阻擋紫外光的照射者，皆可用於本 發明，在不脫離本發明之精神與範疇的情況下所做的修 改或潤飾，皆屬於本發明所保護的範圍。 在前述蝕刻方法中，用以作為蝕刻液的化學溶液， 其pH值須大於11或是小於3。舉例而言，當前述氮 化物材料為氮化鎵時，前述電解蝕刻液可為氫氧化鉀 (KOH)、鹽酸(HC1)或磷酸(H3P〇4)。 8 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 五 另外，则前述電解_的方式 須局部鑛上金屬電極，且該 =枓上Xing etch time relationship diagram. The π X attachment shows a photograph of an electron microscope using the present invention. For the gallium nitride insect chip, the reference numerals after the engraving indicate the insulating base 10; cavity column 12; ruthless nine-slot 14; fixture 16; mercury lamp 20; power supply 25; gaseous material is good. ≫ Λ lice Material 30; metal wire 40; galvanometer 50; etching groove 60. Description of Examples In the method of the nitride material of the present invention, in order to 'fix the nitride material and provide a light source for irradiating the nitride material while the nitride material is being etched, the present invention uses as shown in FIG. The illustrated clamping lighting device includes an insulating base 1G having a cavity column 12 'in the base 10 for setting a light source; and a light transmitting groove 14 formed on a surface of the base 10 for The light generated by the light source disposed in the cavity column 12 can be emitted to the outside of the base 10; a plurality of fixtures 16 are formed on both sides of the light-transmitting groove 14 to clamp the nitride material. In order to prevent the base 10 from being eroded during the etching process, Teflon may be used as a material. The cavity column 12 in the base can be a quartz tube. The light emitted by the aforementioned light source can be radiated to the outside through a quartz tube and a light transmitting slot. And the wavelength (frequency) of the light source used must meet the energy of the light. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) —l · ---------- οι Installation IΓ I:- -I (Please read the notes on the back of the -M first and then fill out this page) Order A7 B7 printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (5) ~ — (hv) is larger than the conductive band of the nitride material and The energy band between valence bands (£ 0. Where h is the Planck constant and v is the frequency of light. As a result, electrons in the nitride material can be excited from the valence band to the conductive band to form heat. Free electrons so as to form a path in the etching bath. Please refer to FIG. 2 > which shows a front view of the clamping lighting device shown in FIG. For example, a mercury lamp 20 capable of emitting deep ultraviolet light with a wavelength of 254 nm is provided, and a nitride material 30 such as gallium nitride, aluminum indium gallium nitride, and the like can be held by a plurality of clamps 16 and fixed to the base. Seat 10, and one of the nitride materials 30 faces the aforementioned light-transmitting groove 14, so the Ultraviolet light can be irradiated onto the nitride material 30 through the light-transmitting groove 14. In addition, the power supply 25 is used to provide the power required for the mercury lamp 20 to emit light. Please refer to FIG. The device structure for realizing the etching method of the nitride material of the present invention includes: an etching tank 60, which is filled with electrolytic etching solution; a clamping lighting device 10 shown in FIG. 2, and a mercury lamp 20 is set inside Partially immersed in the electrolytic etching solution, while the nitride material 30 is also completely immersed in the electrolytic etching solution; a metal wire 40, partially immersed in the electrolytic etching solution, and electrically connected to nitrogen through a galvanometer 50 On the material 30. Using the device shown in FIG. 3, the method of engraving the nitride material of the present invention includes the following steps: (1) setting the nitride material 30 on the holding lighting device 10; (ii) holding the holding device 10; Both the lighting device 10 and the nitride material 30 are immersed in an electrolytic etching solution; (iii) the mercury lamp 20 is used to emit a wavelength of 254 nm; the paper scale is a financially acceptable household standard rate (CNS) A4% grid (210X297 mm) I.- ------- ΟΊI-I--:, (please read the back first Please note this page before filling in this page)-Order · i. A7 B7 V. The deep ultraviolet light of the description of the invention (6) irradiates the nitride material 30; (iv) the galvanometer 50 is used to monitor the etching current (ie the loop current) In order to control the etching depth in real time. In the above embodiment, the mercury lamp emitting a deep ultraviolet light with a wavelength of 254nm has a power intensity of only about 10 mW / cm2. It is far lower than the hundreds or even thousands of mW / cm2 of the prior art. Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs (please read the notes on the back before writing this page) For the above embodiment of the present invention, the following modifications can be made to obtain another different embodiment. That is, if a material that does not absorb ultraviolet light is used, for example, quartz is used as an etching bath, the mercury lamp can be placed outside the etching bath without having to be placed in a clamping lighting device, as long as the UV light can be avoided during implementation. Activation and absorption effects of the etching solution. In addition, the shortest emission wavelength of the aforementioned lighting lamp is 254nm, but the light source of the present invention is not limited to mercury lamps. Other devices with shorter emission wavelengths can also achieve the purpose of the invention, such as excimer laser light sources (KrF248nm, ArF193nm , 'F2157nm excimer laser) or YAG laser (1064nm) conversion output above four times or D2 deuterium lamp. As for the clamping lighting device, since there is no need to provide a light source, it can be simplified in this embodiment. Anyone who can fix the nitride material without blocking the ultraviolet light can be used in the present invention without departing from the present invention. Modifications or retouching made under the spirit and scope of the invention belong to the protection scope of the present invention. In the aforementioned etching method, the pH of the chemical solution used as the etching solution must be greater than 11 or less than 3. For example, when the aforementioned nitride material is gallium nitride, the aforementioned electrolytic etching solution may be potassium hydroxide (KOH), hydrochloric acid (HC1), or phosphoric acid (H3P04). 8 This paper size is in accordance with Chinese National Standard (CNS) A4 specification (210X297 mm). 5 In addition, the aforementioned electrolysis method requires local metal electrodes, and this = 枓 上
fu—於氮化㈣㈣許親和力ΛΛΓ； 極，亦可使用雙層電極，例如錢合金，藉以提= 的速度，對於雙層電極的要求為外層電H 於内層電極的功函數。舉例而言，前述雙層電極= 電極可為包含鈦、釩、鉻、梦：不之内層 ,鍇鉬、铪、鈕或是鎢或其 組成者’而别述雙層電極之外層電極則可為包含鍊、翻、 釕、鍺、鈀、金、銥或是鎳或其組成者。 與先前技術㈣，_本發明所提出之_方法， 可提供極佳⑽刻表面平整度，在先前技術中所能達到 的表面平整度約僅為刚nm，而在本發明中，以㈣ 4〇〇n:的氮化鎵為例，其表面不平整度僅增加4nm。 «月參閱附件之照片，其係顯示運用本發明對於氮化 鎵蟲晶片蚀刻之實施例的電子顯微鏡照片。在此實施例 中，氮化鎵晶片被浸泡於pH值為2的磷酸蝕刻液中，晶 片之照光面積與不照光面積的比為5 : !，光源的功率 強度為lOmW/cm2。照片中電子束掃瞄式顯微鏡（SEM)的 經濟部中央標準局員工消費合作社印製 照相結果，蝕刻面積為6mmx6mm，蝕刻深度為2μηι， 而平整度的變異僅有5% ^本實施例的η-型（濃度為 10 cm )氮化鎵磊晶厚度為2 5μιη，由於磊晶層初始的成 長品質受到藍寶石（sapphire)基板應變（14%)的作用所產 生的缺陷結構，而導致蝕刻表面的平整度在蝕刻到蟲晶層 底部時變得稍差。但是本實施例的蝕刻平整變異度僅約為 本紙張尺度適用中國國家標準（CNS) A4規格（21Gx297公羡） A7 A7 經濟部中央標準局員工消費合作社印製 五、發明説明（8 ) 5%，仍遠優於先前技術中所得到的2〇〜8〇%的變異度。 再者，利用本㈣之方法，無須使科加偏壓，而 银刻速率在無外加偏壓的情況下，可藉由照光強度與受 光面積比例的調整，在25 nm/min至4〇(Wmin之間變 化。故而此方法適於量產，在操作上也相當容易。 請參閱第4圖’其係綠示運用本發明之電解银刻液， 蝕刻速率與PH酸驗值關係的圖式。圖示有效的作用範圍 為值大於11及小於3，其中曲線a表示電解触刻液 為氫氧化卸’而曲線B表示電解触刻液為磷酸。在此pH 值範圍巾，可有效地將經由照光反應所生成之氮化嫁的 氧化物，溶解於蝕刻液當中。如圖所示，蝕刻係在晶片 之照光面積與不照光面積的比為5 : i ’而光源的功率 強度為lOmW/cm2的條件下完成❶最快的蝕刻速率在ρΉ 值為0.5時’可達到80nm/miii。 明參閱第5圖’其續示了本發明中即時監控光電流 之電流密度與蝕刻時間關係的圖式。在圖中顯示了將氮 化鎵晶片浸泡於pH值為11的氫氧化鉀電解液，於照光 則後’光電流隨時間的變化情形。圖示照光時間為15〇〇 秒’而電流監控時間讀取1600秒。只有當氮化鎵受到254 nm紫外光照射時’才量測到一平穩的蝕刻光電流反應過 程的讀取值。當光源關閉時，電流立刻衰減到零值，表 示沒有光反應過程發生。因此，只要對在某一個特定的 p Η值之電解液下作蝕刻光電流讀值以及蝕刻深度的校正 之後，便可應用此技術進行蝕刻速度的即時監控。 本紙張尺度適用中國國家標準（CNS ) Α4規格（210X297公釐） (請先.Μ讀背面之注意事項再填寫本頁) -------Γ--------3-#^—---------1Τ——Γ n n I. \"""/ ^ --- IT - - I — -- n - m 1^1fu—the affinity of the nitride ㈣㈣ΛΓ; can also use a double-layer electrode, such as money alloy, so as to increase the speed, the requirement for the double-layer electrode is the work function of the outer layer of electricity H to the inner layer of the electrode. For example, the aforementioned double-layer electrode = the electrode may include titanium, vanadium, chromium, dream: no inner layer, rhenium-molybdenum, rhenium, button, or tungsten or a combination thereof; and the outer-layer electrode of the double-layer electrode may be It includes a chain, a ruthenium, a ruthenium, a germanium, a palladium, a gold, an iridium, or a nickel or a combination thereof. Compared with the prior art, the method proposed by the present invention can provide excellent surface flatness of the engraving. The surface flatness that can be achieved in the prior art is only about nm, and in the present invention, it is ㈣ 4 Onn: As an example, the surface roughness of the gallium nitride has only increased by 4 nm. «Refer to the attached photograph for an electron microscope photograph showing an example of etching a gallium nitride wafer using the present invention. In this embodiment, the gallium nitride wafer is immersed in a phosphoric acid etching solution having a pH of 2, the ratio of the illuminated area to the unlit area of the wafer is 5:!, And the power intensity of the light source is 10 mW / cm2. The electron beam scanning microscope (SEM) in the photo printed the photographic results of the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. The etching area is 6mmx6mm, the etching depth is 2μηι, and the flatness variation is only 5%. ^ In this embodiment -Type (concentration: 10 cm) gallium nitride epitaxial thickness is 25 μm, because the initial growth quality of the epitaxial layer is affected by the defect structure of the sapphire substrate strain (14%), resulting in the etched surface The flatness becomes slightly worse when etched to the bottom of the worm crystal layer. However, the variation of the etching level in this embodiment is only about the paper size applicable to the Chinese National Standard (CNS) A4 specification (21Gx297). A7 A7 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (8) 5% , Still far better than the 20 ~ 80% variability obtained in the prior art. In addition, by using the method of the present invention, there is no need to make a bias voltage, and the silver engraving rate can be adjusted from 25 nm / min to 40% by adjusting the ratio of the light intensity to the light receiving area without the external bias voltage. Wmin varies. Therefore, this method is suitable for mass production, and it is also quite easy to operate. Please refer to Figure 4 ', which is a diagram showing the relationship between the etching rate and the pH acid test value using the electrolytic silver etching solution of the present invention. The effective range of the figure is greater than 11 and less than 3, where curve a indicates that the electrolytic etching solution is dehydrogenated and curve B indicates that the electrolytic etching solution is phosphoric acid. In this pH range, it can effectively convert The nitrided oxide produced by the light reaction is dissolved in the etching solution. As shown in the figure, the ratio of the illuminated area to the non-illuminated area of the wafer is 5: i 'and the power intensity of the light source is 10 mW / The fastest etching rate can be achieved under the condition of cm2. When the value of ρ is 0.5, it can reach 80nm / miii. Refer to FIG. 5 for details. It continues to show the relationship between the current density and the etching time of the instant monitoring photocurrent in the present invention. The figure shows the gallium nitride The tablet was immersed in a potassium hydroxide electrolyte with a pH of 11, and the photocurrent changed over time after being irradiated. The photoirradiation time is 15000 seconds and the current monitoring time is 1600 seconds. Only when nitriding When gallium was irradiated with ultraviolet light at 254 nm, a stable reading of the photocurrent reaction process was measured. When the light source was turned off, the current immediately decayed to zero, indicating that no photoreaction process occurred. Therefore, as long as the After the etching photocurrent reading and etching depth are corrected under a specific p Η value electrolyte, this technology can be applied for real-time monitoring of the etching speed. This paper size applies the Chinese National Standard (CNS) Α4 specification (210X297) (Mm) (Please read the precautions on the back before filling in this page) ------- Γ -------- 3-# ^ —--------- 1Τ— --Γ nn I. \ " " " / ^ --- IT--I —-n-m 1 ^ 1