201232836 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種LED晶片之製造方法，該LED晶片具有 如下構造：於透光性基板之一側之主面（作為表面側）上形成 有產生發出光之LED元件，而於另一主面（作為背面側）上形 成具有將該發出光反射這一性質之反射膜。 w 【先前技術】 對於構造為於晶片狀之藍寶石基板上形成有包含冚族氮 〇 化物系半導體之LED元件主體的LED晶片，例如可以藍色系 發光二極管（LED)之形式予以產品化。 最近，利用如下之LED晶片，其為了提高來自LED晶片之 發出光之獲取效率，於發出光可透過之透光性基板（藍寶石201232836 VI. [Technical Field] The present invention relates to a method of manufacturing an LED wafer having a structure in which a main surface (as a surface side) on one side of a light-transmitting substrate is formed An LED element that emits light is generated, and a reflective film having the property of reflecting the emitted light is formed on the other main surface (as the back side). [Prior Art] An LED chip in which an LED element main body including a bismuth nitride-based semiconductor is formed on a wafer-shaped sapphire substrate can be produced, for example, in the form of a blue light-emitting diode (LED). Recently, LED wafers have been used which emit light-transmissive light-transmitting substrates (sapphire in order to improve the efficiency of light emission from LED chips)
基板等）之背面側形成金屬反射膜，不僅有效利用了自LED 元件主體直接射出之發出光，且有效利用了暫時入射至基 板内且由背面側之金屬反射膜反射後再次穿過基板而射出 之發出光（參照專利文獻1)。A metal reflective film is formed on the back side of the substrate or the like, and not only the emitted light that is directly emitted from the LED element body but also the inside of the substrate is used, and is reflected by the metal reflective film on the back side and then passed through the substrate again. Light is emitted (see Patent Document 1).
Q 圖ό係表示在透光性基板之背面側形成有反射膜之led 晶片的典型例之GaN系LED之剖面構造圖。 〖 於藍寶石基板10之第一主面（表面）上形成有半導體積層 .構造’該半導體積層構造包括如下兩個區域：一區域中依 次積層有GaN緩衝層12、η型GaN層13、η型AlGaN層14、包 含GalnN之發光層15、p型AlGaN層16、及p型GaN層17 ;另 一區域中’ η型AlGaN層14、發光層15、p型AlGaN層16、p 型GaN層17之一部分經蝕刻而除去，直至GaN層13之一 158359.doc 201232836 部分露出為止。於該半導體積層構造之外周面，除電極形 成部分之外形成有Si〇2膜18作為絕緣保護膜。而且，於p型Q is a cross-sectional structural view of a GaN-based LED which is a typical example of a led wafer in which a reflective film is formed on the back side of a light-transmitting substrate. A semiconductor laminate is formed on the first main surface (surface) of the sapphire substrate 10. The semiconductor laminate structure includes two regions: a GaN buffer layer 12, an n-type GaN layer 13, and an n-type layer in this region. The AlGaN layer 14, the light-emitting layer 15 including GalnN, the p-type AlGaN layer 16, and the p-type GaN layer 17; the other portion of the 'n-type AlGaN layer 14, the light-emitting layer 15, the p-type AlGaN layer 16, and the p-type GaN layer 17 A portion of it is removed by etching until a portion of 158359.doc 201232836 of GaN layer 13 is exposed. On the outer peripheral surface of the semiconductor laminate structure, an Si 2 film 18 is formed as an insulating protective film in addition to the electrode forming portion. Moreover, in p type
GaN層17上形成有透光性P型電極19(Au薄膜），於η型GaN層 ^上形成有n型電極2〇(Ti/Ai/Au膜）。 於藍寳石基板1〇之第二主面（背面側）上形成有反射膜 11 °反射膜11係使用對於來自發光層15之發出光之波長具 有良好的反射特性之材料，具體而言，例如形成有一層Au 膜’藉此’將欲自背面穿過之發出光向藍寶石基板1〇侧反 射。 另外，反射膜11中，考慮到LED元件之發光特性及材料 成本，除了 Au膜之外，亦可使用入丨膜或介電多層膜作為反 射膜之材料。亦即，根據LED元件主體之半導體材料之種 類及膜厚，發光波長區域（發光光譜）會有所不同，因此，可 對應於元件及LED(商品）而選擇使用對發光波長之反射特 性良好的材料。例如，當利用塗佈於元件周邊的螢光材料 之螢光光束之情形時，亦考慮到該影響而選擇材料。具體 而言，若為白色LED(包含螢光材料及藍色LED之白色 LED或者包含RGB 3波長營光材料及紫光源之白色led)， 則有時可使用可見光波長即約35〇 nm〜8〇〇 nm之波長區域 内之反射率優良的介電多層膜。另一方面，當優先考慮材 料成本之情形時，可使用A1膜。 背面側形成有反射膜的LED晶片係經過以下之製造步驟 而製造。亦即，將晶圓狀之藍寶石基板用作母板，首先， 於母板之第一主面（表面）上以格子狀之圖案形成元件 158359.doc 201232836 主體’接著，將背面研磨至所需的厚度之後，於母板之第 二主面（背面）形成反射膜（元件形成步驟）。此後，為了分割 成各個LED元件主體，將藍寶石基板分割成晶片狀從而作 為LED晶片（產品）而取出（晶片分割步驟）。 此處，關於自母板分割成各個LED晶片之晶片分割加工 進行說明。-般而言，於LED晶片之製造步驟中，亦與其 他半導體產品-樣，當將母板分割成各個晶片時，實施利 用切割刀（切塊機，dicer)、鑽石劃線器（diamond scdber)等 之機械加工，或者實施利用照射雷射光束之任一種雷射加 工而進行的分割。 其中，當利用使用切割刀或鑽石劃線器等加工工具之機 械劃線加工來分割母板之情形時，因為藍寶石係比玻璃等 硬得多的脆性材料，故而加工工具容易磨損，而且經加工 的刀割面上除了所需的裂紋（crack)以外還容易產生會導致 產品不良的碎屑（chipping)。 〇 另方面田利用YAG雷射等高輸出脈衝雷射（脈寬 10-Mo·7秒）之雷射加工來分割母板之情形時，採用周知之 技術即雷射燒姓（Laser Ablation)或多光子吸收進行分割。 亦即’將雷射光束彙聚到基板表面附近或者基板内部，使 基板表面附近產生燒姓而形成溝槽，或利用多光子吸收而 在基板内部形成加工變質部，從而使該等加工部分成為用 於斷開之分割起點（參照專利文獻2、專利文獻3)。 然而，當利用雷射對硬脆性材料即藍寶石進行加工之情 形時’在燒钱、多光子吸收中之任一種情況下，均需要使 158359.doc 201232836 照射能量高於對玻璃等進行加工時之照射能量。結果，當 利用燒蝕進行加工之情形時’形成之溝槽寬度變寬。當藉 由多光子吸收來設置基板内部之加工變質部之情形時，變 質部位亦變寬，且變質部位所形成之分割面之表面粗糙度 變粗’未必能夠獲得具有良好的精度之分割面。 因此’提出使用脈寬為1 〇-1 0秒以下之超短脈衝雷射（以下 將脈寬為10 1Q秒以下之脈衝雷射稱作「超短脈衝雷射」）之 新的雷射加工方法（以下之本說明書中亦稱作別法）（參照專 利文獻4)。因此，使用Nd:YAG雷射（波長1〇64 nm)，調整焦 點使其射出，以使具有極短的脈寬及高功率密度之超短脈 衝雷射彙1於藍寶石基板之表面附近。此時之雷射光束於 聚光點附近以外不被基板材料（藍寶石）吸收，但於聚光點上 引起多光子吸收，從而瞬間且局部地產生熔融、昇華（局部 之微小燒蝕）。而且，於基板之表層部位至表面之範圍内形 成微小裂紋。亦即，先前之燒蝕中，照射之雷射光束所產 生的幾乎所有能量均被基板材料之熔融、蒸騰所耗費，用 於形成大的燒蝕孔（孔徑為8 μιη左右），而新的雷射加工方 法（ΒΙ法）中，照射雷射之能量僅一部分被微小熔融痕（孔徑 為1 左右的小孔）之形成所耗費，其餘的能量則作為形成 微小裂紋之衝擊力而耗f。沿著預定分割線如穿孔般分散 地形成上述溶解痕，藉此，形成鄰接之溶解痕之間以微小 =裂紋連接而成之易分離區域，⑫而可沿著該區域分割基 [先行技術文獻] 158359.doc 201232836 [專利文獻] [專利文獻1]日本專利特開平10_308532號公報 [專利文獻2]日本專利特開平u_177137號公報 [專利文獻3]日本專利特開2〇〇4_2683〇9號公報 [專利文獻4]日本專利特開2005-271563號公報 【發明内容】 [發明所欲解決之問題] 中 7使用雷射燒餘加 、利用超短脈衝雷射之新 於LED製造中之晶片分割步驟中， 工、利用多光子吸收之雷射加工、利 型雷射加工（BI法）’對此，上文已作說明。 然而，當將背面側形成有反射膜之母板分割而切取咖A translucent P-type electrode 19 (Au thin film) is formed on the GaN layer 17, and an n-type electrode 2 (Ti/Ai/Au film) is formed on the n-type GaN layer. A reflective film 11 is formed on the second main surface (back side) of the sapphire substrate 1 . The reflective film 11 is a material having good reflection characteristics for the wavelength of light emitted from the light-emitting layer 15 , specifically, for example, A layer of Au film is formed 'by this' to reflect the light emitted from the back side toward the side of the sapphire substrate 1 . Further, in the reflective film 11, in consideration of the light-emitting characteristics and material cost of the LED element, in addition to the Au film, a tantalum film or a dielectric multilayer film may be used as the material of the reflective film. In other words, depending on the type and thickness of the semiconductor material of the LED element body, the light-emitting wavelength region (light-emitting spectrum) is different. Therefore, it is possible to selectively use the reflection characteristics for the light-emitting wavelength in accordance with the device and the LED (product). material. For example, when a fluorescent beam of a fluorescent material applied to the periphery of the element is used, the material is selected in consideration of the influence. Specifically, in the case of a white LED (a white LED including a fluorescent material and a blue LED or a white LED including an RGB 3 wavelength camping material and a violet light source), a visible light wavelength of about 35 〇 nm to 8 may be used. A dielectric multilayer film excellent in reflectance in a wavelength region of 〇〇nm. On the other hand, when the material cost is prioritized, the A1 film can be used. The LED chip on which the reflective film is formed on the back side is manufactured by the following manufacturing steps. That is, the wafer-shaped sapphire substrate is used as a mother board. First, the element is formed in a lattice pattern on the first main surface (surface) of the mother board. 158359.doc 201232836 body 'Next, the back surface is ground to the desired After the thickness, a reflective film is formed on the second main surface (back surface) of the mother board (element forming step). Thereafter, in order to divide into individual LED element bodies, the sapphire substrate is divided into wafers and taken out as LED chips (products) (wafer dividing step). Here, the wafer dividing process in which the mother board is divided into individual LED chips will be described. In general, in the manufacturing process of the LED chip, similar to other semiconductor products, when the mother board is divided into individual wafers, a cutter (dicer), a diamond scriber (diamond scdber) is used. Or machining or other division by laser processing using any of the irradiated laser beams. Among them, when the mother board is divided by mechanical scribing using a processing tool such as a dicing blade or a diamond scriber, since the sapphire is a much harder brittle material than glass, the processing tool is easily worn and processed. In addition to the required crack, the cut surface of the knife is prone to chipping which may cause defective products. When another field uses the laser processing of a high-output pulsed laser (pulse width of 10-Mo·7 seconds) using a YAG laser to divide the mother board, the well-known technique is Laser Ablation or Multiphoton absorption is used for segmentation. That is, 'the laser beam is concentrated near the surface of the substrate or inside the substrate, and a groove is formed in the vicinity of the surface of the substrate to form a groove, or a processed metamorphic portion is formed inside the substrate by multiphoton absorption, thereby making the processed portion useful. The starting point of the division at the break (see Patent Document 2 and Patent Document 3). However, when using a laser to process a hard and brittle material, sapphire, in the case of burning money or multiphoton absorption, it is necessary to make the 158359.doc 201232836 irradiation energy higher than when processing glass or the like. Irradiation energy. As a result, the groove width formed when the processing is performed by ablation is widened. When the processed metamorphic portion inside the substrate is provided by multiphoton absorption, the modified portion is also widened, and the surface roughness of the divided surface formed by the modified portion becomes thicker. It is not always possible to obtain a split surface having good precision. Therefore, it is proposed to use a new laser processing using an ultrashort pulse laser with a pulse width of 1 〇-1 0 or less (hereinafter, a pulse laser with a pulse width of 10 1Q seconds or less is called "ultra-short pulse laser"). The method (hereinafter also referred to as another method in the present specification) (refer to Patent Document 4). Therefore, using a Nd:YAG laser (wavelength 1 〇 64 nm), the focal point is adjusted to be emitted so that an ultrashort pulse laser having a very short pulse width and a high power density is placed near the surface of the sapphire substrate. At this time, the laser beam is not absorbed by the substrate material (sapphire) except for the vicinity of the condensing point, but causes multiphoton absorption at the condensing point, thereby instantaneously and locally generating melting and sublimation (local partial ablation). Further, minute cracks are formed in the range from the surface layer portion to the surface of the substrate. That is to say, in the previous ablation, almost all the energy generated by the irradiated laser beam is consumed by the melting and transpiration of the substrate material, and is used to form a large ablation hole (the aperture is about 8 μm), and the new one. In the laser processing method (the method), only a part of the energy of the laser irradiation is consumed by the formation of a minute melt mark (a small hole having a pore diameter of about 1), and the rest of the energy is consumed as an impact force for forming a microcrack. Forming the above-mentioned dissolution marks in a dispersed manner along a predetermined dividing line, such as a perforation, thereby forming an easily separable region in which adjacent dissolution marks are connected by minute=cracks, and 12 can be divided along the region. [Prior Art Paper] [Patent Document 1] Japanese Patent Laid-Open Publication No. JP-A No. Hei. No. Hei. No. Hei. [Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-271563 [Draft of the Invention] [Problems to be Solved by the Invention] In the seventh, the use of laser burn-in, the use of ultrashort pulse laser, the new wafer segmentation in LED manufacturing In the step, the laser processing using the multiphoton absorption and the sharp laser processing (BI method) are described above. However, when the mother board on which the reflective film is formed on the back side is divided, the coffee is cut.
雷射光束之發光同樣會影響LED元件主體，產生導致led 元件自身之發光效率下降的問題，因&，自維持發光效率 之觀點出發’希望自背面側進行雷射照射。The light emission of the laser beam also affects the main body of the LED element, causing a problem that the luminous efficiency of the LED element itself is lowered. From the viewpoint of maintaining luminous efficiency, it is desirable to perform laser irradiation from the back side.
增膘等材料之使用，但並未自晶 片分割步驟之觀點出發來 158359.doc 201232836 考慮反射骐較佳為哪一種膜。 板！二：對於構造為於背面側形成有A1膜等反射膜的母 則進行雷射照射而形成分割起點之情形時，首 ^ 曰 出，接著，《刀割線以帶狀除去（剝離）反射膜而使母板露 /士自母板之背面側向露出部分照射雷射光束。 /時而要沿著預定分割線利用由光微影法而形成 案進仃剥離、或者以用於除去反射膜的照射條件（與下 文所述之用於形成分割起點之雷射照射不同）來進行用於 ^反，膜的雷射齡’但在任—種情況下，均另外需要 ’口著預疋分割線呈格子狀除去(剝離)反射膜之步驟,成為導 致加工工時增加之要因。 對此，本發明之目的在於提供一種led之製造方法，其 ;月面幵/成有反射膜之母板自背面側進行雷射照射而 形成分割起點之情形時’無需預先另外沿著預定分割線除 去反射膜。 [解決問題之技術手段] 為了達成上述目的而成之本發明之LED晶片之製造方 法，包括對於母板沿著預定分割線照射雷射光束從而形成 用於分剔成各個led元件主體之分割起點之步驟，該母板 中’於透光性基板之表面側以圖案形成有複數個LED元件 主體’且於背面側包括預定分割線上之部位在内形成有反 射膜’且上述製造方法包含以下之構成。 亦即’作為反射膜，於背面側形成具有如下性質之反射 膜’並且以使雷射光束自背面側透過反射膜而直接照射到 I58359.doc 201232836 基板背面之方式對基板進行雷射加工；上述反射膜之性質 為：將LED元件主體射出之發出光之波長範圍（更佳為來自 螢光材料之螢光光束之波長範圍）反射，並且使照射至預定 分割線上之雷射光束之波長光透過。 此處，透光性基板亦可為藍寶石基板。 另外’亦可為，反射膜其4〇〇 nm〜700 nm之可見光區域之 反射率為90%以上，900 nm以上之紅外區域之透過率為5〇% 以上。 具體而s，反射膜亦可由介電多層膜形成。 另外，作為雷射光束，可照射利用Nd · YAG雷射之1〇64订爪 之脈衝雷射。 進而，作為脈衝雷射，亦可將脈寬短於1〇.1()秒之超短脈 衝雷射沿著預定分割線分散地照射，從而形成分割起點。The use of materials such as enthalpy, but not from the point of view of the wafer segmentation step 158359.doc 201232836 Consider which membrane is preferred. board! (2) When a mother who is formed with a reflection film such as an A1 film on the back side is subjected to laser irradiation to form a division starting point, the first step is ejected, and then the "knife cutting line removes (peeles) the reflection film in a strip shape. The mother board exposed/steel is irradiated to the exposed light beam from the back side of the mother board to the exposed portion. / occasionally, along the predetermined dividing line, the film is formed by photolithography, or by irradiation conditions for removing the reflective film (unlike the laser irradiation for forming a segmentation starting point described later) In the case of the laser age of the film, in the case of any of the above, the step of removing the (peeling) reflective film in a lattice shape is required, which is a factor causing an increase in processing time. In view of the above, an object of the present invention is to provide a method for manufacturing a LED, which is a case where a mother panel with a reflective film is irradiated with laser light from the back side to form a split starting point. The wire removes the reflective film. [Technical means for solving the problem] The method for manufacturing an LED chip of the present invention, which is achieved by the above object, comprises irradiating a laser beam along a predetermined dividing line with respect to a mother board to form a dividing starting point for dividing into individual LED element bodies. In the mother board, a plurality of LED element bodies are formed in a pattern on the surface side of the light-transmitting substrate, and a reflective film is formed on a portion of the back surface side including a predetermined dividing line. The manufacturing method includes the following Composition. That is, as a reflective film, a reflective film having the following properties is formed on the back side, and the laser beam is directly irradiated to the back surface of the I58359.doc 201232836 substrate by passing the laser beam from the back side through the reflective film; The property of the reflective film is to reflect the wavelength range of the emitted light emitted from the main body of the LED element (more preferably, the wavelength range of the fluorescent light beam from the fluorescent material), and transmit the wavelength light of the laser beam irradiated onto the predetermined dividing line. . Here, the light-transmitting substrate may be a sapphire substrate. Further, the reflection film may have a reflectance of 90% or more in a visible light region of 4 〇〇 nm to 700 nm, and a transmittance of 5 〇% or more in an infrared region of 900 nm or more. Specifically, the reflective film may also be formed of a dielectric multilayer film. Further, as the laser beam, a pulsed laser using a 1 〇 64 pin of the Nd · YAG laser can be irradiated. Further, as the pulse laser, an ultrashort pulse laser having a pulse width shorter than 1 〇.1 (second) may be scatteredly irradiated along a predetermined dividing line to form a dividing starting point.
此處，所謂“分散地照射，，係指如下所述之隔著間隔之照 射’即’利用新型雷射加卫方法（職）隔著距離分散地進行 照射’藉此’隔著間隔而形成微小的熔融痕（孔徑為工μιη左 右之小孔但鄰接之炼融痕之間所形成之微小裂紋彼此相 連。亦即，以炼融痕及微小裂紋相連之方式形成，因此， 以使裂紋不斷進展之方式誘導而進行加工。 如上所述’沿著敎分割線如穿孔般分散地形成上述溶 解痕’藉此，形成鄰接之溶解痕之間以微小裂紋相連之易 分離區域’從而基板可沿著該區域分割。 [發明之效果] 片之製造方法 根據本發明之LED晶Here, the term "dispersively irradiated" means that the irradiation is performed at intervals along the following, that is, 'the laser irradiation method is used to spread the dispersion by a new laser-assisted method." Tiny melt marks (a small hole having a pore diameter of about μηη, but tiny cracks formed between adjacent smelting marks are connected to each other. That is, a combination of a smelting mark and a minute crack is formed, so that the crack is continuously The process of progress is induced and processed. As described above, 'the above-mentioned dissolution marks are dispersedly formed along the ruthenium dividing line as a perforation, thereby forming an easily separable region where the adjacent dissolution marks are connected by microcracks' so that the substrate can be along The region is divided. [Effect of the invention] Method for manufacturing a sheet LED crystal according to the present invention
作為形成於使LED 158359.doc 201232836 元件之發出光透過之透過性基板之背面側之反射膜所具有 的光學特性，具有如下性質：可將LED元件主體及螢光材 料之波長區域之光反射，並且使照射至預定分割線上之雷 射光束之波長光透過，藉此，當沿著預定分割線進行雷射 照射之情形時，若自背面側進行照射，則雷射光束會透過 反射膜而直接照射至基板上。 亦即，之前係藉由預先除去反射膜而使雷射光束照射至 基板上，但於背面側設有反射膜之狀態下進行雷射照射之 情形時，雷射光束亦會到達基板背面，能夠進行與實質上 無反射膜時相同的雷射加工》 藉此，於具有背面反射膜之LED晶片之製造中，無需沿 著預定分割線除去反射膜之步驟，從而能減少加工工時。 【實施方式】 以下，以使用m族氮化物系半導體之LED晶片為例根 據圖式依次詳細說明本發明之lED晶片之製造步驟。本發 明之LED晶片之製造方法主要包括元件形成步驟及晶片分 割步驟之兩個步驟。 (元件形成步驟） 在元件形成步驟中，於母板之表面侧（第一主面側）以圖 案形成多個LED元件主體，並且於背面侧（第二主面側）形成 反射膜。 圖1係表示在母板之表面側形成有led元件主體之狀態 的圖式’圖1(a)為俯視圖（表面側之平面圖），圖丨^)為正視 圖。母板1係由晶圓形狀之藍寶石基板構成，於表面ia(第 158359.doc •10- 201232836 一主面）上以形成正方格子之方式以圖案形成有縱橫規則 排列之多個LED元件主體2。各個LED元件主體2具有圖6所 不之元件構造’且由周知之半導體製造製程形成。 再者，於鄰接之元件主體2之間設有間隙，上述間隙即為 分割成各個LED元件主體時之預定分割線。 用作母板1之藍寳石係對於LED元件主體2發光之波長區 域（350 nm〜8〇〇 nm)具有透光性的材料。另外，只要是對於 LED元件主體2之發光波長區域具有透光性之材料，則亦可 〇 使用藍寶石基板以外之材料來作為基板。當LED元件主體2 並非白色發光二極管而是單色光發光二極管之情形時，只 要是對於相應之單色光之發光波長而非對於整個可見光區 域具有透光性即可。 圖2係表示在形成有LED元件主體2之母板1之背面侧形 成有反射膜之狀態的圖式，圖2(a)為仰視圖（背面側之平面 圖）’圖2(b)為正視圖。於母板1之整個背面側b形成有反射 膜3。 ❹ 作為反射膜3，可使用具有選擇性地反射led元件主體2 之發出光、且使照射至預定分割線上之雷射光束之波長光 透過之性質的材料。作為雷射光束，通常使用9〇〇 ηηι以上 之波長光即紅外雷射（YAG雷射、YVO雷射等），因此可使用 使900 nm以上之紅外波長區域透過之反射材料。 具體而言，較佳為使用如下之反射膜，即例如將4〇〇 nm〜700 nm之波長區域之光以90%以上的反射率反射、將 Nd:YAG雷射之波長光（1〇64 nm)以50%以上之透過率透過。 158359.doc 201232836 圖3係表示反射膜3之理想的反射光譜之圖式。 接近於上述特性之反射膜可由介電多層膜形成。 (晶片分割步驟） 接著’將形成有LED元件主體2及反射膜3之母板分割成 各個LED晶片。 圖4係表示利用雷射照射來將母板分割成各個led晶片 時之加工狀態之圖式。 作為雷射4使用Nd:YAG脈衝雷射，於波長l〇64nm、脈宽 2〇皮秒、脈衝能量0.1一〜50^11、重複頻率10]&112〜20〇〖沿、 預疋分割線方向上之掃描速度50 mm/秒〜3 000 mm/秒之條 件下’自背面lb側照射超短雷射光束。另外，作為掃描速 度’兼顧到重複頻率，與前一照射位置之間隔（照射間距) 為 3 μηι〜20 μπι 〇 並且，由雷射4所内置之透鏡光學系統（未圖示）調整焦 點’以使深度方向之焦點位置彙聚於比基板背面側115略微 靠近基板内側之位置Α(分割起點）。 若以上述方式照射雷射，則雷射光束L會透過反射膜3直 接到達母板1之焦點位置而發揮作用，藉由一方面使母板工 移動-方面進行加工，可以3 μπι〜2()叫之間隔分散地形成 小孔，鄰接之孔與孔之間形成微小裂紋，藉此，形成作為 分割起點之加工線（劃線線）。沿著所有的格子狀之預定分割 線重複進行相同的處理，從而形成用於分割成各個led元 件主體之分割起點。 圖5係表不對於形成有分割起點之母板丨進行斷開處理之 158359.doc 12 201232836 狀態之圖式。 使斷開棒5對準與分割起點A形成之位置相向之表面側之The optical characteristics of the reflective film formed on the back side of the transparent substrate through which the light emitted from the LED 158359.doc 201232836 element is transmitted have the property of reflecting light in the wavelength region of the LED element main body and the fluorescent material. And transmitting the wavelength light of the laser beam irradiated onto the predetermined dividing line, whereby when the laser beam is irradiated along the predetermined dividing line, if the light is irradiated from the back side, the laser beam passes through the reflecting film directly Irradiation onto the substrate. In other words, the laser beam is irradiated onto the substrate by removing the reflection film in advance, but when the laser beam is irradiated in a state where the reflection film is provided on the back side, the laser beam can reach the back surface of the substrate. The same laser processing as in the case of substantially no reflection film is performed. Thus, in the manufacture of an LED wafer having a back reflection film, it is not necessary to remove the reflection film along a predetermined division line, and the number of processing steps can be reduced. [Embodiment] Hereinafter, the steps of manufacturing the lED wafer of the present invention will be sequentially described in detail based on the LED chips of the group m nitride-based semiconductor. The method of manufacturing an LED wafer of the present invention mainly comprises two steps of a component forming step and a wafer dividing step. (Element forming step) In the element forming step, a plurality of LED element bodies are patterned on the surface side (first main surface side) of the mother board, and a reflective film is formed on the back side (second main surface side). Fig. 1 is a view showing a state in which a main body of a led element is formed on a surface side of a mother board. Fig. 1(a) is a plan view (a plan view on the front side), and Fig. 1 is a front view. The mother board 1 is composed of a wafer-shaped sapphire substrate, and a plurality of LED element bodies 2 are regularly formed in a pattern on the surface ia (the first main surface of the 158359.doc •10-201232836) in a square lattice manner. . Each of the LED element bodies 2 has an element structure 'not shown in Fig. 6 and is formed by a well-known semiconductor manufacturing process. Further, a gap is provided between the adjacent element bodies 2, and the gap is a predetermined dividing line when the main body of each LED element is divided. The sapphire used as the mother board 1 is a material having a light transmissive property in a wavelength region (350 nm to 8 〇〇 nm) in which the LED element main body 2 emits light. Further, as long as it is a material having light transmissivity in the light-emitting wavelength region of the LED element body 2, a material other than the sapphire substrate may be used as the substrate. In the case where the LED element body 2 is not a white light emitting diode but a monochromatic light emitting diode, it is only necessary to have light transmissivity for the light emission wavelength of the corresponding monochromatic light, not for the entire visible light region. 2 is a view showing a state in which a reflective film is formed on the back side of the mother substrate 1 on which the LED element body 2 is formed, and FIG. 2(a) is a bottom view (a plan view on the back side). FIG. 2(b) is a front view. Figure. A reflective film 3 is formed on the entire back side b of the mother board 1. ❹ As the reflective film 3, a material having a property of selectively reflecting the emitted light of the LED element main body 2 and transmitting the wavelength light of the laser beam irradiated onto the predetermined dividing line can be used. As the laser beam, an infrared laser (YAG laser, YVO laser, or the like) of a wavelength of 9 〇〇 ηηι or more is usually used, and therefore, a reflective material that transmits an infrared wavelength region of 900 nm or more can be used. Specifically, it is preferable to use a reflective film in which light of a wavelength region of 4 〇〇 nm to 700 nm is reflected by a reflectance of 90% or more and a wavelength of light of a Nd:YAG laser (1 〇 64). Nm) is transmitted at a transmittance of 50% or more. 158359.doc 201232836 FIG. 3 is a view showing an ideal reflection spectrum of the reflective film 3. A reflective film close to the above characteristics may be formed of a dielectric multilayer film. (Wafer Dividing Step) Next, the mother board on which the LED element body 2 and the reflecting film 3 are formed is divided into individual LED chips. Fig. 4 is a view showing a state of processing when laser light is used to divide a mother board into individual led wafers. As the laser 4, use Nd:YAG pulse laser at wavelength l〇64nm, pulse width 2〇 picosecond, pulse energy 0.1~50^11, repetition frequency 10]&112~20〇 The ultra-short laser beam is illuminated from the back lb side under the condition of a scanning speed of 50 mm/sec to 3 000 mm/sec in the line direction. Further, as the scanning speed 'the repetition frequency is taken, the interval from the previous irradiation position (irradiation pitch) is 3 μηι to 20 μπι, and the focus optical system (not shown) built in the laser 4 adjusts the focus ' The focus position in the depth direction is concentrated on a position Α (segment starting point) slightly closer to the inner side of the substrate than the substrate back side 115. When the laser is irradiated in the above manner, the laser beam L is directly transmitted to the focal position of the mother board 1 through the reflective film 3, and the mother board is moved and processed on the one hand, and can be 3 μπι 2 ( The small holes are formed in a spaced manner, and microscopic cracks are formed between the adjacent holes and the holes, thereby forming a processing line (scribe line) as a starting point of the division. The same processing is repeated along all of the grid-shaped predetermined dividing lines to form a dividing starting point for dividing into individual LED element bodies. Fig. 5 is a diagram showing the state of the 158359.doc 12 201232836 state in which the mother board 形成 having the division starting point is not broken. Aligning the break bar 5 with the surface side facing the position where the split start point A is formed
位置P卜並且，使支撐棒6a、6b於背面侧對準與分割起點A 相離而位於其左右兩側之位置？2、p3，從而以3點支撐之狀 態施加彎曲力矩，藉此沿著預定分割線進行斷開。然後， 沿著所有的分割起點執行相同的斷開處理，藉此可分割成 每個LED晶片。 因此，根據本發明，於形成反射膜3之後，可不沿著預定 〇 分割線剝離反射膜3，而是立刻對母板自身進行雷射加工。 上述實施形態中係利用照射超短脈衝雷射來進行晶片分 割，但亦可採用先前之燒蝕加工、或者利用多光子吸收之 加工。該等情形時，可不沿著預定分割線來剝離形成於背 面侧之反射膜’而是立刻進行雷射加工。 [產業上之可利用性] 本Ιχ明可用於製造基板背面形成有反射膜之晶片。 ^ 【圖式簡單說明】 圖Ua)、（b)係表示在母板之表面側形成有lED元件主體 之狀態之圖式。 圖2(a)、（b)係表示在形成有LED元件主體之母板之背面 側形成有反射膜之狀態之圖式。 圖3係表示反射膜之理想的反射光譜之圖式。 圖4係表示利用雷射照射來將母板分割成各個lED晶片 時之加工狀態之圖式。 圖5係表示沿著分割起點進行斷開處理之狀態之圖式。 158359.doc -13. 201232836 圖6係表示LED元件主體之構造之一例之剖面圖 【主要元件符號說明】 1 透光性基板（藍寶石基板） la 表面側 lb 背面側 2 LED元件主體 3 反射膜 4 雷射（Nd:YAG雷射） 5 斷開棒 6a、6b 支撐棒 A 焦點位置（分割起點） L 雷射光束 158359.doc - 14-At the position P, the support bars 6a, 6b are aligned on the back side with respect to the division starting point A and located at the left and right sides thereof. 2, p3, thereby applying a bending moment in a state of 3 points of support, thereby breaking along a predetermined dividing line. Then, the same disconnection process is performed along all the division start points, whereby it can be divided into each LED wafer. Therefore, according to the present invention, after the reflective film 3 is formed, the reflective film 3 can be peeled off along the predetermined 分割 dividing line, and the mother plate itself can be subjected to laser processing at once. In the above embodiment, wafer division is performed by irradiation of an ultrashort pulse laser, but it is also possible to use a previous ablation process or a process using multiphoton absorption. In such a case, the laser film formed immediately on the back side may be peeled off along the predetermined dividing line, and laser processing may be performed immediately. [Industrial Applicability] The present invention can be used to manufacture a wafer in which a reflective film is formed on the back surface of a substrate. ^ [Simple description of the drawings] Figs. Ua) and (b) show a state in which the main body of the lED element is formed on the surface side of the mother board. Figs. 2(a) and 2(b) are views showing a state in which a reflective film is formed on the back side of the mother board on which the LED element main body is formed. Fig. 3 is a view showing an ideal reflection spectrum of a reflective film. Fig. 4 is a view showing a state of processing when laser light is used to divide a mother board into individual lED wafers. Fig. 5 is a view showing a state in which the disconnection processing is performed along the division start point. 158359.doc -13. 201232836 Fig. 6 is a cross-sectional view showing an example of the structure of the main body of the LED element. [Description of main components] 1 Translucent substrate (sapphire substrate) la Surface side lb Back side 2 LED element body 3 Reflecting film 4 Laser (Nd:YAG laser) 5 Disconnect rod 6a, 6b Support rod A Focus position (segmentation starting point) L Laser beam 158359.doc - 14-