1232604 九、發明說明： 【發明所屬之技術領域】 本發明是有關使用藍寶石基板之氮化鎵系發光二極體，特 別是有關一種於此發光二極體藍寶石基板之一侧形成一金屬 反射層之方法。 【先前技術】 由於行動通訊之普及，發光二極體於各種輕薄短小之消費 性電子產品之應用極為廣泛，而以氮化鎵化合物為材料更是製 作發光二極體之技術主流。 如第一圖所示，習知之氮化鎵發光二極體，其傳統結構係 以藍寶石為基板10，然後在此藍寳石基板1〇之一侧，依序從 下而上为別蠢晶形成一氮化嫁緩衝層11、一 N型氮化嫁歐姆 接觸層12、一氮化銦鎵發光層13、一 P型氮化铭鎵披覆層14、 一 P型氮化鎵歐姆接觸層15、一透光導電層16，最後，再於 透光導電層16與N型氮化鎵歐姆接觸層12上分別形成一正電 極巧，17與負電極襯墊18。請注意到，在此傳統結構下之氮 化鎵系發光二極體，其發光層所發出之光線有部份會向下穿透 藍寶石基板而被封裝固晶用之膠材吸收而降低其發光效率。 …為改善前述傳統結構之氮化鎵系發光二極體之發光效 率、美國專利地6121636號揭露了一種如第二圖所示之纟士構， 此結構係以藍寶石為基板20，然後在此藍寶石基板2〇之°一侧 ^表面依序從下而上分縣晶形成—氮化鎵缓衝層 2卜一 N型氮化鎵歐姆接觸層22、一氮化銦鎵發 一 P =氮化贿披覆層24、— P型氮化鎵歐姆接觸層2日5、一透 f ’再於透光導電層26與N型氮化鎵歐姆接觸層22 電1概塾/與負電極她28，最後，再於藍 j基板20之另-侧之表φ 2〇,錄上一層 金屬反射層29。此金屬反射層可將朝向表面 1232604 ^朝向表面20 之方向，進而增加此結構發光二極體之 效率。 然經實驗發現，依此結構製作發光二極體時，若單純以研 磨、、拋光及清潔處理藍寶石基板2〇之表面2〇,後，再以蒸鍍 方式，上銀(Ag)或鋁(A1)之金屬反射層29，此金屬反射層29 之黏著性甚差，極容易於後續之晶粒製作程序中剝落，導致依 此結構製作發光二極體極高的不良率。 【發明内容】 、為克，先前技術之缺點，本發明乃提出一種針對以藍寶石 為基板之氮化鎵系發光二極體，能同時提高其發光效率盘 良率之金屬反射層製作方法。 本發明所提出之金屬反射層製作方法，係於個別之發光二 極體晶粒形成於晶圓之上後進行。本發明形成此金屬反射層^ 步驟包括·先將藍寶石基板無蟲晶成長之一侧研磨並拋光至一 特定厚度；將此拋光後之此侧以電漿離子予以表面處理；再以 電子束蒸鍍法於此侧形成一特定厚度之金屬反射層。 、茲配合下列圖示、實施例之詳細說明及申請專利範圍，將 上述及本發明之其他目的與優點詳述於後。 【實施方式】 第二圖係依據本發明形成金屬反射層之氮化鎵系發光二 極體之結構示意圖。如第三圖所示，此氮化鎵系發光二極體之 晶圓係以藍寶石為基板30，然後在此藍寶石基板3〇之一第二 表面30’ ’，依序從下而上分別遙晶形成—氮化嫁緩衝層 31、: N型氮化鎵歐姆接觸層32、一氮化銦鎵發光層33、一 P型氮化鋁鎵披覆層34、以及一 P型氮化鎵歐姆接觸層35。 在完成上述之磊晶成長後，接著以乾式蝕刻法，將部份之N型 氮化鎵歐姆接觸層32、氮化銦鎵發光層33、p型氮化鋁 1232604 覆層34、以及P型氮化鎵歐姆接觸層35移除以暴露出n 化鎵歐姆接觸層32之一部份表面32a，。 乳 接著’形成一透光導電層於該p型氮化鎵歐姆接觸層 方，再於禮透光導電層36與N型氮化鎵歐姆接觸層之部产 面32a上分別形成一正電極襯墊37與負電極襯墊38。" 77 ，下再以第四A、B、C、D圖分別說明本發明之—實 之各巧步驟：以形成-金屬反射層於—依照前述f知技術 個別，化鎵系敍二極體晶粒之·，以及最後 晶粒與此晶圓分離： 合個 (1) ^第四A圖所示，將藍寶石基板3〇之無遙晶成 一表面30研磨並拋光至厚度約8〇〜2〇〇//m ; 罘 ⑵如第四B圖所7F，將研磨、拋光後之第一表面3〇, 氧(02)或氬(Argon)之電漿離子予以表面處理 面30,之原子狀態； 又炎弟表 f面在第一表面3〇’上相對於另一側第二 長之區域’以電子束蒸鑛法形成一厚度 約500〜4000A之金屬反射層39。此金 ς 之ϋ 一 )、金(AU)、與銦(Ιη)其中之-所構成 ⑷如第四D ®所*，再以伽或雷 及劈裂機(Breaker)，從藍寶石美杯qn /结:職tolber) 將_之”—曰基板之第二表面30,，侧， 將個^之日aMB日®上分離喊成_之發光二極體。 挪囉係骑依贿制知技術形 成個別亂化㈣發先二極體晶粒之晶圓，以形 層，以及最後如何將該各個晶粒與此晶、’、 ⑴如第五A圖所示，將藍寶石基板3〇之 -表面3〇,研磨並拋光至厚度約8〇〜2〇〇_「、日日 1232604 2)如第五B圖所示，將研磨、拋光後之第一表面3〇，，以 氧(02)或氬(Argon)之電漿離子予以表面處理，以改變第一表 面30’之原子狀態； (3)如第五C圖所示，在第一表面3〇,上相對於另一侧第二 表面30 有磊晶成長之區域，以習知之光罩蝕刻技術定義 出相對之^切割走道，接著以電子束蒸鍍法形成一厚度約 500〜4000A之金屬反射層39。此金屬反射層之材質為銀(Ag)、 鋁(A1)、與铑(Rh)其中之一，或是銀(Ag)、鋁(A1)、或铑(Rh) 其中^一與鈦(Ti)、金(Au)、與銦（In)其中之一所構成之合 金，最後以金屬剝離技術將切割走道上之金屬反射 層去除而完成。 /(4)如第五D圖所示，再以鑽石或雷射之切割機及劈裂機， 從藍寶石基板30之第一表面3〇，側，將個別之晶粒從晶圓上 分離而完成個別之發光二極體。 、惟，以上所述者，僅為本發明之較佳實施例而已，當不能 =此限林發明實施之脑。即大凡依本發明t請專利範圍所 作之均等變化與修飾，皆應仍屬本發明專利涵蓋之範圍内。 【圖式簡單說明】 ==圖係傳統結構之氮化鎵系發光二極體之結構示意圖。 圖係依據先前技術改善發光效率之氮化鎵系發光二極體 之結構示意圖。 圖係依據本發明形成金屬反射層之氮化鎵系發光二極體 <、、、口構不意圖。 A、B、C、D圖係分別說明本發明之一實施例之各個步驟， >成一金屬反射層於一依照習知技術形成個別氮化鎵系發 一二極體晶粒之晶圓，以及最後將該各個晶粒與此晶圓分離之 不思圖。 第五A B、C、D圖係分別說明本發明之另一實施例之各個步 123之6〇4 以形成一金屬反射層於一依照習知技術形成個別氣化鎵系 $極體晶粒之晶圓，以及最後將該各個晶粒與此晶圓分離 〜不思圖。 【主要元件符號說明】 藍寶石基板 」氮化鎵緩衝層 13 14 15 16 17 18 20 20, N型氮化鎵歐姆接觸層 氮化銦鎵發光層 P型氮化鋁鎵彼覆層 P型氮化鎵歐姆接觸層 透光導電層 正電極襯塾 負電極襯墊 藍寶石基板 藍寶石基板之一侧面 藍寶石基板之另一侧面 21 氮化鎵緩衝層 22 N型氮化鎵歐姆接觸層 23 氮化銦鎵發光層 24 P型氮化鋁鎵彼覆層 25 P型氮化鎵歐姆接觸層 26 透光導電層 27 正電極襯墊 28 負電極襯墊 29 金屬反射層 30藍寶石基板 第一表面 3〇,，第二表面 氮化鎵緩衝層 N型氮化鎵歐姆接觸層 N型氮化鎵歐姆接觸層32之一部份表面 氮化銦鎵發光層 P型氮化銘鎵彼覆層 P型氮化鎵歐姆接觸層 透光導電層 正電極襯墊 負電極襯墊 金屬反射層 101232604 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a gallium nitride light-emitting diode using a sapphire substrate, and more particularly to a metal reflective layer formed on one side of the light-emitting diode sapphire substrate. Method. [Previous technology] Due to the popularity of mobile communications, light-emitting diodes are widely used in a variety of light, thin and short consumer electronics products, and gallium nitride compounds are the mainstream technology for making light-emitting diodes. As shown in the first figure, the conventional structure of the conventional gallium nitride light-emitting diode is based on a sapphire substrate 10, and then one side of the sapphire substrate 10 is sequentially formed from the bottom to the top as a stupid crystal. A nitrided buffer layer 11, an N-type nitrided ohmic contact layer 12, an indium gallium nitride light-emitting layer 13, a P-type nitride gallium cladding layer 14, a P-type gallium nitride ohmic contact layer 15 A transparent conductive layer 16, and finally, a positive electrode 17, and a negative electrode pad 18 are formed on the transparent conductive layer 16 and the N-type gallium nitride ohmic contact layer 12, respectively. Please note that under the traditional structure of the gallium nitride light-emitting diode, part of the light emitted by the light-emitting layer will penetrate downward through the sapphire substrate and be absorbed by the glue for encapsulating the crystal to reduce its light emission. effectiveness. … In order to improve the luminous efficiency of the GaN-based light-emitting diode of the aforementioned conventional structure, US Patent No. 6121636 discloses a silicon structure as shown in the second figure. This structure uses sapphire as the substrate 20, and then here On the side of the sapphire substrate 20 °, the surface is sequentially formed from the bottom to the top-gallium nitride buffer layer 2-an N-type gallium nitride ohmic contact layer 22-an indium gallium nitride-P = nitrogen Chemical coating layer 24, P-type gallium nitride ohmic contact layer 2, 5, f 'and then transparent conductive layer 26 and N-type gallium nitride ohmic contact layer 22 28. Finally, on the other side of the blue j substrate 20, φ 20, a metal reflective layer 29 is recorded. The metal reflective layer can be oriented toward the surface 1232604 ^ toward the surface 20, thereby increasing the efficiency of the light emitting diode of this structure. However, it was found through experiments that when the light-emitting diode is manufactured according to this structure, if the surface 20 of the sapphire substrate 20 is simply treated by grinding, polishing, and cleaning, then silver (Ag) or aluminum ( A1) metal reflective layer 29. The metal reflective layer 29 has poor adhesion and is very easy to be peeled off in the subsequent die-making process, resulting in a very high defect rate of light-emitting diodes manufactured according to this structure. [Summary of the Invention] In order to overcome the shortcomings of the prior art, the present invention proposes a method for manufacturing a metal reflective layer for a gallium nitride-based light emitting diode using sapphire as a substrate, which can simultaneously improve the luminous efficiency of the disk. The manufacturing method of the metal reflective layer proposed in the present invention is performed after individual light emitting diode crystal grains are formed on a wafer. The method of forming the metal reflective layer according to the present invention includes: firstly grinding and polishing one side of the sapphire substrate without insect crystal growth to a specific thickness; this polished side is surface-treated with plasma ions; and then subjected to electron beam evaporation The plating method forms a metal reflective layer with a specific thickness on this side. In conjunction with the following drawings, detailed description of the embodiments and the scope of patent application, the above and other objects and advantages of the present invention will be described in detail below. [Embodiment] The second diagram is a schematic structural diagram of a gallium nitride-based light emitting diode in which a metal reflective layer is formed according to the present invention. As shown in the third figure, the wafer of this gallium nitride-based light-emitting diode uses sapphire as the substrate 30, and then one of the sapphire substrates 30 has a second surface 30 '' in order from the bottom to the top. Crystal Formation—Nitride-buffered buffer layer 31, N-type gallium nitride ohmic contact layer 32, an indium gallium nitride light emitting layer 33, a P-type aluminum gallium nitride coating layer 34, and a P-type gallium nitride ohmic Contact layer 35. After the above epitaxial growth is completed, a portion of the N-type GaN ohmic contact layer 32, the indium gallium nitride light-emitting layer 33, the p-type aluminum nitride 1232604 cladding layer 34, and the P-type are then dry-etched. The gallium nitride ohmic contact layer 35 is removed to expose a part of the surface 32a of the gallium nitride ohmic contact layer 32. Next, a light-transmitting conductive layer is formed on the p-type gallium nitride ohmic contact layer, and a positive electrode liner is formed on each of the production surfaces 32a of the light-transmitting conductive layer 36 and the N-type gallium nitride ohmic contact layer. Pad 37 and negative electrode pad 38. " 77, and the fourth A, B, C, and D diagrams will be used to explain the present invention-the practical steps: to form-a metal reflective layer-in accordance with the above-mentioned known technology, the gallium-based dynode The bulk grains and the final grains are separated from this wafer: (1) ^ As shown in the fourth A, the sapphire substrate 30 is ground and polished to a surface 30 and polished to a thickness of about 80 ~ 2000 // m; 罘 ⑵As shown in Figure 4F of Figure 4B, the first surface after grinding and polishing 30, the plasma ion of oxygen (02) or argon (Argon) to the surface treatment surface 30, State; the second surface of the Yandi surface f is formed on the first surface 30 ′ with respect to the second longest region on the other side ′ by a metal reflection method 39 having a thickness of about 500˜4000 A by the electron beam distillation method. This one of gold (1), gold (AU), and indium (Ιη)-constituted as the fourth D ® *, then with Gamma or Thunder and Breaker, from the sapphire beauty cup qn / 结: totolber) will be "the second surface of the substrate 30 ,, side, will be separated on the aMB day ® on the day of the ^ into a light-emitting diode _. The technology is based on bribery system Form individual scrambled wafers that emit pre-diode grains, shape the layers, and finally how to combine each of these grains with this crystal, as shown in Figure 5A, sapphire substrate 30- Surface 30, ground and polished to a thickness of about 80-200_ ", day-to-day 1232604 2) As shown in Figure 5B, the ground and polished first surface 30, with oxygen (02) Or plasma ion of Argon is surface-treated to change the atomic state of the first surface 30 '; (3) As shown in the fifth figure C, the second surface on the first surface 30, relative to the second side There is an epitaxial growth area on the surface 30. The relative ^ cutting path is defined by the conventional mask etching technology, and then a metal reflection layer 39 with a thickness of about 500 to 4000 A is formed by the electron beam evaporation method. This metal reflection The material is one of silver (Ag), aluminum (A1), and rhodium (Rh), or one of silver (Ag), aluminum (A1), or rhodium (Rh) ^ and titanium (Ti), gold ( Au) and an alloy composed of one of indium (In), and finally the metal reflection layer on the cutting aisle is removed by metal stripping technology. / (4) As shown in the fifth D figure, then diamond or thunder The slicing cutter and splitter separate the individual dies from the wafer from the first surface 30 and the side of the sapphire substrate 30 to complete individual light-emitting diodes. However, the above-mentioned only This is only the preferred embodiment of the present invention, when it cannot be equal to the brain of the implementation of this limited invention. That is, all the equivalent changes and modifications made in accordance with the scope of the patent claimed by the invention should still fall within the scope of the invention patent. Brief description of the drawings] == The diagram is a schematic diagram of the structure of a gallium nitride based light emitting diode with a traditional structure. The diagram is a diagram of the structure of a gallium nitride based light emitting diode with improved light emitting efficiency according to the prior art. The diagram is according to the present invention The gallium nitride-based light-emitting diodes forming the metal reflective layer are not intended. A, B, C, D Each step of an embodiment of the present invention is explained separately, > forming a metal reflective layer on a wafer of individual gallium nitride system emitting a diode crystal according to a conventional technique, and finally Wonderful map of wafer separation. The fifth AB, C, and D diagrams are illustrations of steps 123 to 604 of another embodiment of the present invention to form a metal reflective layer and to form individual vaporizations according to conventional techniques. The wafer of the gallium-based $ polar body die, and finally separate each die from this wafer ~ no picture. [Description of the main component symbols] Sapphire substrate "GaN buffer layer 13 14 15 16 17 18 20 20 , N-type gallium nitride ohmic contact layer Indium gallium nitride light-emitting layer P-type aluminum gallium nitride layer P-type gallium nitride ohmic contact layer light-transmitting conductive layer positive electrode liner negative electrode liner sapphire substrate sapphire substrate The other side of the side sapphire substrate 21 GaN buffer layer 22 N-type gallium nitride ohmic contact layer 23 Indium gallium nitride light-emitting layer 24 P-type aluminum gallium nitride coating layer 25 P-type gallium nitride ohmic contact layer 26 Photoconductive layer 27 Positive electrode pad 28 Negative electrode pad 29 metal reflective layer 30 sapphire substrate first surface 30, second surface gallium nitride buffer layer N-type gallium nitride ohmic contact layer N-type gallium nitride ohmic contact layer 32 part of the surface indium gallium nitride light-emitting layer P-type gallium nitride cladding layer P-type gallium nitride ohmic contact layer light-transmitting conductive layer positive electrode pad negative electrode pad metal reflective layer 10