TWI395353B - Method for manufacturing vertical light -emitting diodes - Google Patents
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本發明是有關於一種發光二極體之製造方法,特別是指一種GaN-基垂直式發光二極體的製造方法。The present invention relates to a method of fabricating a light-emitting diode, and more particularly to a method of fabricating a GaN-based vertical light-emitting diode.
傳統橫向結構GaN-基發光二極體(LED),因為使用導電與導熱特性不佳之藍寶石(Al2 O3 ,sapphire)基板,其兩電極需置於磊晶結構之同一側,導致有效發光面積小以及電流流動路徑過長,使其串聯電阻值偏高,並且衍生嚴重之電流擁擠效應(current crowding)。而且橫向結構GaN-基LED於高功率操作下容易產生高溫,如此將導致發光亮度及效率衰減、發光波長改變、可靠性降低,以及LED壽命縮短等缺失。Conventional lateral structure GaN-based light-emitting diode (LED), because the use of sapphire (Al 2 O 3 , sapphire) substrate with poor conductivity and thermal conductivity, the two electrodes should be placed on the same side of the epitaxial structure, resulting in effective light-emitting area Small and current flow paths are too long, causing their series resistance values to be high and deriving severe current crowding. Moreover, the lateral structure GaN-based LED is prone to high temperatures under high power operation, which will result in a loss of luminance and efficiency, a change in the wavelength of the emission, a decrease in reliability, and a shortened life of the LED.
目前有一種垂直結構GaN-基LED,以高導電與導熱特性之置換基板來取代藍寶石基板,經實驗證實可以有效改善上述問題,以提升GaN-基LED於高功率領域之應用。其中,利用雷射剝離技術(Laser lift-off,LLO)剝離藍寶石基板並整合具高散熱與低串聯阻值之電鍍金屬基板,或者利用半導體基板、金屬基板進行晶片鍵合(wafer bonding)之新基板技術,目前已廣泛使用於高功率垂直結構GaN-基LED之製作。然而,上述垂直結構GaN-基LED之製程具有下列缺點:(1)以電鍍為主之金屬基板技術,其LED磊晶晶片必需先經過酸洗、去離子水洗滌與電鍍等步驟,過程相當繁雜 。(2)業界於晶片鍵合技術中常用的銅、鎳或其他合金基板,則因其熱膨脹係數與GaN-基材料不同,極易發生熱應力及穩定性問題。(3)此外,晶片鍵合製程需要涉及高溫(200~550℃)與高壓,此乃為了使LED晶片上之金屬電極與替代藍寶石基板之新基板進行黏合及歐姆接觸。以Au-Si(金-矽)鍵結為例(亦即Au電極以及替換的矽基板之鍵結),所需之製程溫度與壓力分別為350~380℃與20~35 kg/cm2 。其高溫高壓的製程複雜不易控制、元件接觸電阻偏高,並且導致嚴重的磊晶微破碎(micro-cracks),使產品良率低且光電特性低劣。At present, there is a vertical structure GaN-based LED, which replaces the sapphire substrate with a high-conductivity and thermal-conducting replacement substrate. It has been experimentally confirmed that the above problems can be effectively improved to enhance the application of the GaN-based LED in the high-power field. Among them, the sapphire substrate is stripped by a laser lift-off (LLO), and a plated metal substrate having high heat dissipation and low series resistance is integrated, or wafer bonding is performed using a semiconductor substrate or a metal substrate. Substrate technology has been widely used in the fabrication of high power vertical structure GaN-based LEDs. However, the above process of the vertical structure GaN-based LED has the following disadvantages: (1) the metal substrate technology mainly based on electroplating, and the LED epitaxial wafer must be subjected to steps such as pickling, deionized water washing and electroplating, and the process is quite complicated. . (2) Copper, nickel or other alloy substrates commonly used in wafer bonding technology in the industry are subject to thermal stress and stability problems due to their different thermal expansion coefficients from GaN-based materials. (3) In addition, the wafer bonding process involves high temperature (200 ~ 550 ° C) and high voltage, in order to make the metal electrode on the LED wafer and the new substrate instead of the sapphire substrate bonding and ohmic contact. Taking Au-Si (gold-ruthenium) bonding as an example (that is, the bonding of the Au electrode and the replacement germanium substrate), the required process temperature and pressure are 350 to 380 ° C and 20 to 35 kg / cm 2 , respectively . The process of high temperature and high pressure is difficult to control, the contact resistance of components is high, and severe micro-cracks are caused, resulting in low product yield and poor photoelectric characteristics.
由以上說明可知,上述垂直式GaN-基LED之製程仍有待改善。As can be seen from the above description, the process of the above vertical GaN-based LED still needs to be improved.
因此,本發明之目的,即在提供一種可以提高製程良率、降低接觸電阻、保有元件良好光電特性的垂直式發光二極體之製造方法。Accordingly, it is an object of the present invention to provide a method of manufacturing a vertical light-emitting diode that can improve process yield, reduce contact resistance, and maintain good photoelectric characteristics of components.
本發明垂直式發光二極體之製造方法,包含以下步驟(1)準備一轉換基板。A method of manufacturing a vertical light-emitting diode according to the present invention comprises the following steps (1) of preparing a conversion substrate.
(2)在該轉換基板上披覆一緩衝層(buffer layer)。(2) A buffer layer is coated on the conversion substrate.
(3)在該緩衝層上披覆一發光單元。(3) A light-emitting unit is coated on the buffer layer.
(4)在該發光單元上披覆一金屬接觸層單元。(4) A metal contact layer unit is coated on the light emitting unit.
(5)在該金屬接觸層單元上披覆一附著反射層單元。(5) coating an adhesion reflective layer unit on the metal contact layer unit.
(6)在該附著反射層單元上形成一異方性導電膠層。(6) Forming an anisotropic conductive adhesive layer on the adhesion reflective layer unit.
(7)在該異方性導電膠層上黏著一支持基板。(7) A supporting substrate is adhered to the anisotropic conductive adhesive layer.
(8)移除該轉換基板及緩衝層。(8) The conversion substrate and the buffer layer are removed.
(9)在該發光單元上披覆一電極。(9) An electrode is coated on the light emitting unit.
步驟(5)之附著反射層單元係利用蒸鍍、濺鍍或離子鍍法沉積於該金屬接觸層單元上,所述附著反射層單元包括四層附著反射層。該等附著反射層是選自下列材料:鈦(Ti)、鋁(Al)、金(Au)、鎳(Ni)、銀(Ag)、鉑(Pt)、鈀(Pd)、金/鋅(Au/Zn)、金/鈹(Au/Be)、金/鍺(Au/Ge)、金/鍺/鎳(Au/Ge/Ni)、銦(In)、錫(Sn)、鋅(Zn)所構成之群組,及其任一組合。The attached reflective layer unit of the step (5) is deposited on the metal contact layer unit by evaporation, sputtering or ion plating, and the attached reflective layer unit comprises four layers of an attached reflective layer. The adhesion reflective layer is selected from the group consisting of titanium (Ti), aluminum (Al), gold (Au), nickel (Ni), silver (Ag), platinum (Pt), palladium (Pd), gold/zinc ( Au/Zn), Au/Be, Au/Ge, Au/Ge/Ni, In (In), Tin (Sn), Zinc (Zn) The group formed, and any combination thereof.
步驟(6)之異方性導電膠層,是於該附著反射層單元表面塗佈異方性導電膠膜(Anisotropic Conductive Film,ACF)材料而形成,所述異方性導電膠膜材料是於樹脂中加入導電粒子所構成,兼具單向導電及膠合固定的功能,而且具有良好之熱穩定性及彈性,利用異方性導電膠層作為黏著層,有助於後續支持基板之壓合鍵結的黏著作業。而該異方性導電膠層之彈性,可以用楊氏模量(Young’s modulus)E值來判斷,E為產生每單位應變所需之應力〔E=應力(stress)/應變(strain)〕,E值越小表示較柔軟且較具緩衝能力。適合作為本發明異方性導電膠層者,為4×109 帕(Pa,亦即N/m2 )≦E≦8×109 帕(Pa),如此可以提供適當彈性,以承受後續製程之壓力。The anisotropic conductive adhesive layer of the step (6) is formed by coating an anisotropic conductive film (ACF) material on the surface of the adhesion reflective layer unit, and the anisotropic conductive adhesive film material is The resin is composed of conductive particles, which has the functions of unidirectional conduction and gluing, and has good thermal stability and elasticity. The anisotropic conductive adhesive layer is used as an adhesive layer to facilitate the press-bonding of the subsequent supporting substrate. Sticky work. The elasticity of the anisotropic conductive layer can be judged by the Young's modulus E value, which is the stress (E=stress/strain) required to produce a strain per unit. The smaller the E value, the softer and more buffering. Suitable as the anisotropic conductive adhesive layer of the present invention, which is 4×10 9 Pa (Pa, ie, N/m 2 )≦E≦8×10 9 Pa (Pa), which can provide appropriate elasticity to withstand subsequent processes. The pressure.
該異方性導電膠層之厚度為d,較佳地5 μm≦d≦20 μm,因為該異方性導電膠層太薄而不足5 μm時,會削弱其受壓緩衝能力,太厚則會增加寄生串聯電阻。The thickness of the anisotropic conductive adhesive layer is d, preferably 5 μm≦d≦20 μm, because the anisotropic conductive adhesive layer is too thin and less than 5 μm, the pressure buffering capacity is weakened, and the thickness is too thick. Will increase the parasitic series resistance.
步驟(7)之支持基板可以使用可撓性基板,亦可以使用非可撓性基板。可撓性基板例如金屬薄膜:鋁箔、銅箔、鐵鈷鎳合金(不鏽鋼)、金箔、銀箔、鐵箔或上述任一組合,或者塑膠類高分子聚合物薄片等。非可撓性厚膜基板之材料,例如:矽、氮化鎵、砷化鎵、碳化矽等半導體基板,以及鎳、銅、銅鎳與銅鎢等金屬基板。The support substrate of the step (7) may be a flexible substrate or a non-flexible substrate. The flexible substrate is, for example, a metal film: aluminum foil, copper foil, iron cobalt nickel alloy (stainless steel), gold foil, silver foil, iron foil or any combination thereof, or a plastic polymer sheet. The material of the non-flexible thick film substrate is, for example, a semiconductor substrate such as germanium, gallium nitride, gallium arsenide or tantalum carbide, and a metal substrate such as nickel, copper, copper nickel or copper tungsten.
步驟(7)是利用一晶片黏著機將進行完步驟(1)~(6)的試片與該支持基板相互壓合黏著。所述黏著壓力為P,黏著溫度為T,黏著時間為t,較佳地9kg/cm2 ≦P≦25 kg/cm2 ,25℃≦T≦180℃,5秒≦t≦900秒。當作業溫度過低時,會導致膠聯程度(curing degree)不足,使得元件牢固性(robustness)下降。而黏著壓力過低而小於9 kg/cm2 時,或者黏著時間過短亦會導致黏著牢固性不足。黏著時間過長或溫度過高,則會導致膠體特性產生變化。In the step (7), the test piece of the steps (1) to (6) and the support substrate are pressed and adhered to each other by a wafer bonding machine. The adhesive pressure is P, the adhesive temperature is T, and the adhesive time is t, preferably 9 kg/cm 2 ≦P ≦ 25 kg/cm 2 , 25 ° C ≦ T ≦ 180 ° C, 5 seconds ≦ t ≦ 900 seconds. When the operating temperature is too low, the curing degree is insufficient, so that the robustness of the component is lowered. When the adhesive pressure is too low and less than 9 kg/cm 2 , or the adhesion time is too short, the adhesion is insufficient. If the adhesion time is too long or the temperature is too high, it will cause changes in the colloidal properties.
步驟(8)是使用雷射剝離法來移除轉換基板,所使用的雷射光源為準分子雷射光(excimer laser)。Step (8) is to remove the conversion substrate by using a laser lift-off method, and the laser light source used is an excimer laser.
有關本發明之前述及其他技術內容、特點與功效,在以下配合參考圖式之一個較佳實施例的詳細說明中,將可清楚的呈現。The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.
參閱圖1,本發明垂直式發光二極體之製造方法之一較佳實施例,是用於製造一垂直式發光二極體,所述發光二極體包含:一支持基板26、一位於支持基板26上的異方性導電膠層28、一位於異方性導電膠層28上的附著反射層單 元25、一位於附著反射層單元25上的金屬接觸層單元24、一位於金屬接觸層單元24上的發光單元23,以及一位於發光單元23上的電極27。Referring to FIG. 1 , a preferred embodiment of a method for fabricating a vertical LED is used to fabricate a vertical LED. The LED includes: a support substrate 26 and a support layer. An anisotropic conductive adhesive layer 28 on the substrate 26 and an attached reflective layer on the anisotropic conductive adhesive layer 28 A metal contact layer unit 24 on the attached reflective layer unit 25, a light-emitting unit 23 on the metal contact layer unit 24, and an electrode 27 on the light-emitting unit 23 are provided.
參閱圖2、3、4,本發明垂直式發光二極體之製造方法包含以下步驟:(1)進行步驟11:準備一個藍寶石(Al2 O3 )轉換基板21。Referring to Figures 2, 3 and 4, the method of fabricating a vertical light-emitting diode of the present invention comprises the following steps: (1) performing step 11: preparing a sapphire (Al 2 O 3 ) conversion substrate 21.
(2)進行步驟12:在轉換基板21上披覆一層氮化鎵(GaN)緩衝層22。(2) Step 12: A layer of gallium nitride (GaN) buffer layer 22 is coated on the conversion substrate 21.
(3)進行步驟13:在GaN緩衝層22上披覆該發光單元23,首先於GaN緩衝層22上成長一層由n型氮化鎵(n-GaN)製成的第一披覆層231,再於該第一披覆層231上成長一層具有多重量子井(Multi Quantum Well)結構的主動層232,最後於主動層232上成長一層由p型氮化鎵(p-GaN)製成的第二披覆層233。其中,該主動層232可以為涵蓋GaN系材料的同質結構、異質結構,或量子井結構,故本發明主要是提供一種GaN基的垂直式發光二極體。(3) performing step 13: coating the light-emitting unit 23 on the GaN buffer layer 22, firstly growing a first cladding layer 231 made of n-type gallium nitride (n-GaN) on the GaN buffer layer 22, Further, an active layer 232 having a multi-quantum well structure is grown on the first cladding layer 231, and finally a layer made of p-type gallium nitride (p-GaN) is grown on the active layer 232. Two cladding layers 233. The active layer 232 may be a homogenous structure, a heterostructure, or a quantum well structure covering a GaN-based material. Therefore, the present invention mainly provides a GaN-based vertical light-emitting diode.
(4)進行步驟14:於發光單元23上披覆金屬接觸層單元24,首先將進行完步驟11~13的試片於高溫下活化處理,使p-GaN第二披覆層233的載子濃度提高、增加導電率,並降低接觸電阻。接著對Al2 O3 轉換基板21進行薄化及拋光加工,清洗試片後,即可沉積該金屬接觸層單元24。沉積方式是利用電子束(E-beam)蒸鍍的方式,於第二披覆層233上依序成長一層以鎳(Ni)製成的鎳金屬接觸層241,以及一層以金(Au)製成的金金屬接觸層242,再將試片於溫度 520℃的氧氣氛圍下退火(annealing)15分鐘,並形成鎳、金的金屬氧化物(oxidized-Ni/Au),即完成p型歐姆接觸。此步驟可以使第二披覆層233與後續結合的支持基板26間,有良好的歐姆接觸(ohmic contact)。(4) Step 14: coating the metal contact layer unit 24 on the light-emitting unit 23, first performing the activation of the test piece of the steps 11 to 13 at a high temperature to make the carrier of the p-GaN second cladding layer 233 Increased concentration, increased conductivity, and reduced contact resistance. Next, the Al 2 O 3 conversion substrate 21 is thinned and polished, and after the test piece is cleaned, the metal contact layer unit 24 can be deposited. The deposition method is an electron beam (E-beam) evaporation method, and a nickel metal contact layer 241 made of nickel (Ni) is sequentially grown on the second cladding layer 233, and a layer is made of gold (Au). The gold metal contact layer 242 is formed, and the test piece is annealed in an oxygen atmosphere at a temperature of 520 ° C for 15 minutes to form a nickel-gold metal oxide (oxidized-Ni/Au), thereby completing p-type ohmic contact. . This step allows a good ohmic contact between the second cladding layer 233 and the subsequently bonded support substrate 26.
(5)進行步驟15:利用E-beam蒸鍍方式在金屬接觸層單元24上披覆附著反射層單元25,沉積順序是於金金屬接觸層242上依序成長一層鈦(Ti)附著反射層251、一層鋁(Al)附著反射層252、一層鈦附著反射層253,以及一層金附著反射層254。該附著反射層單元25具有光反射的作用,可以將主動層232產生之部分朝支持基板26行進的光往電極27方向反射,藉此增加LED的發光效率。而且附著反射層單元25與金屬接觸層單元24之間,以及與後續形成的異方性導電膠層28之間,都具有良好的歐姆接觸與附著結合力。(5) Performing step 15: coating the adhesion reflective layer unit 25 on the metal contact layer unit 24 by means of E-beam evaporation, in the order of depositing a layer of titanium (Ti) adhesion reflective layer on the gold metal contact layer 242. 251, a layer of aluminum (Al) adhesion reflective layer 252, a layer of titanium adhesion reflective layer 253, and a layer of gold adhesion reflective layer 254. The adhesion reflection layer unit 25 has a function of light reflection, and can reflect the light generated by the active layer 232 toward the support substrate 26 toward the electrode 27, thereby increasing the luminous efficiency of the LED. Moreover, between the adhesion reflective layer unit 25 and the metal contact layer unit 24, and between the subsequently formed anisotropic conductive adhesive layer 28, there is good ohmic contact and adhesion bonding force.
(6)進行步驟16:形成異方性導電膠層28,此步驟是於金附著反射層254表面利用旋轉塗佈(spin-coating)的方式,塗佈異方性導電膠膜(Anisotropic Conductive Film,ACF)材料,在本實施別中,其厚度約為10~15 μm。(6) Performing step 16: forming an anisotropic conductive adhesive layer 28 by applying an anisotropic conductive film on the surface of the gold-attached reflective layer 254 by spin-coating. , ACF) material, in this embodiment, has a thickness of about 10-15 μm.
(7)進行步驟17:黏著支持基板26,將完成前述步驟的試片置於一晶片黏著機上,再將支持基板26置於該異方性導電膠層28表面,利用該晶片黏著機將試片與該支持基板26相互壓合施力而完成黏著鍵結作業,如此即得到圖3所示之結構。本實施例之晶片黏著機為「聚昌科技股份有限公司」提供之型號「ATS P-bond 100」之儀器。而該支持基 板26為304-L不誘鋼所製成。步驟17之黏著壓力、溫度與時間等參數,與異方性導電膠層28材料種類有關,本實施例採用楊氏模量E約為4×109 帕~8×109 帕的異方性導電膠膜材料,其典型製程參數分別為,黏著壓力25 kg/cm2 ,黏著溫度180℃,黏著時間持續15秒。(7) performing step 17: adhering the support substrate 26, placing the test piece completing the foregoing steps on a wafer bonding machine, and then placing the supporting substrate 26 on the surface of the anisotropic conductive adhesive layer 28, using the wafer bonding machine The test piece and the support substrate 26 are pressed against each other to perform an adhesive bonding operation, and thus the structure shown in FIG. 3 is obtained. The wafer bonding machine of this embodiment is an instrument of the model "ATS P-bond 100" supplied by "Juchang Technology Co., Ltd.". The support substrate 26 is made of 304-L stainless steel. The parameters of adhesion pressure, temperature and time in step 17 are related to the material type of the anisotropic conductive adhesive layer 28. In this embodiment, the anisotropy of Young's modulus E is about 4×10 9 Pa·8×10 9 Pa. Conductive film materials, the typical process parameters are, the adhesion pressure is 25 kg / cm 2 , the adhesion temperature is 180 ° C, the adhesion time lasts 15 seconds.
(8)進行步驟18:移除轉換基板21及緩衝層22,利用KrF準分子雷射光照射試片以進行雷射剝離製程(laser liftoff)來移除轉換基板21。接著使用感應耦合電漿(Inductively coupled plasma,簡稱ICP)蝕刻,移除該GaN緩衝層22,即可得到圖4所示之結構。(8) Step 18: The conversion substrate 21 and the buffer layer 22 are removed, and the test piece is irradiated with KrF excimer laser light to perform a laser liftoff to remove the conversion substrate 21. Then, the GaN buffer layer 22 is removed by etching using an inductively coupled plasma (ICP) to obtain the structure shown in FIG.
參閱圖5,為完成步驟18之雷射剝離製程後的試片俯視圖,其元件之尺寸可藉由光罩定義。經由本發明所採用異方性導電膠層28之彈性可撓性特點,使得完成區塊雷射剝離製程後的GaN基磊晶薄膜(如圖所示的每一正方形區塊)仍完整保留,無一般傳統晶片鍵合技術於雷射剝離後常見之磊晶破碎現象。Referring to FIG. 5, in order to complete the top view of the test piece after the laser stripping process of step 18, the size of the components can be defined by a photomask. Through the elastic flexibility of the anisotropic conductive adhesive layer 28 used in the present invention, the GaN-based epitaxial film after completion of the block laser stripping process (each square block as shown) remains intact. There is no conventional conventional wafer bonding technique for the phenomenon of epitaxial fracture after laser stripping.
(9)進行步驟19:在發光單元23之第一披覆層231表面沉積電極27,所述電極27可以為多層不同材料之堆疊構成,並且可由鈦、鋁、金…等材料的其中一種或任意之組合製成,藉此形成n型接觸,如此即完成圖1之垂直式發光二極體結構的製作。(9) performing step 19: depositing an electrode 27 on the surface of the first cladding layer 231 of the light emitting unit 23, the electrode 27 may be composed of a stack of a plurality of different materials, and may be one of materials such as titanium, aluminum, gold, or the like. Any combination is formed, thereby forming an n-type contact, thus completing the fabrication of the vertical light-emitting diode structure of FIG.
參閱圖6,為本發明垂直式LED與傳統橫向LED電流-電壓特性曲線圖,元件尺寸大小皆為600μm×600μm,圖中顯示本發明操作於電流50mA時,順向偏壓為2.99V,當電 流為300 mA時,順向偏壓為3.82V。而傳統橫向LED於50mA及300 mA之順向偏壓分別為3.46V與4.8V,因此本發明之順向偏壓較傳統橫向LED小。而圖7可觀察出本發明比傳統橫向LED具有更佳的光輸出功率。因為本發明垂直式LED比傳統橫向LED具有較短之垂直導通路徑,以及較大之出光面積,而且配合該異方性導電膠層28之鍵合技術,使本發明製作出的LED品質佳,經雷射剝離所裸露出之n-GaN第一披覆層231亦具有較低之片電阻,使得電流擴展效能較佳。因此本發明垂直LED具有較佳之光電特性、低順向壓降、低寄生串聯電阻,以及較高的發光效率。6 is a current-voltage characteristic diagram of a vertical LED and a conventional lateral LED according to the present invention, and the element size is 600 μm×600 μm. The figure shows that when the current operation is 50 mA, the forward bias voltage is 2.99 V. Electricity When the current is 300 mA, the forward bias is 3.82V. The forward bias voltages of the conventional lateral LEDs at 50 mA and 300 mA are 3.46 V and 4.8 V, respectively, so the forward bias of the present invention is smaller than that of the conventional lateral LED. While Figure 7 shows that the present invention has better optical output power than conventional lateral LEDs. Because the vertical LED of the present invention has a shorter vertical conduction path than the conventional lateral LED, and a larger light-emitting area, and the bonding technology of the anisotropic conductive adhesive layer 28, the LED produced by the present invention has good quality. The n-GaN first cladding layer 231 exposed by laser lift-off also has a lower sheet resistance, so that current spreading performance is better. Therefore, the vertical LED of the present invention has better photoelectric characteristics, low forward voltage drop, low parasitic series resistance, and high luminous efficiency.
參閱圖8,為本實施例所製得的LED,於未撓曲(有效長度L=24 mm)以及撓曲後(有效長度L=15 mm)所測得的電流-主波長(dominant wavelength)特性曲線圖。圖中可看出,在電流為30 mA的操作條件下,未施加外應力(L=24 mm)的LED之原始主波長為465.3 nm,而撓曲形變(L=15 mm)的LED之主波長為465.0 nm,其波長位移量僅為0.3 nm。顯見運用本發明所製出的LED於基板撓曲情況下的發光特性,仍具有極佳之穩定性。Referring to FIG. 8, the LED obtained in the present embodiment has a current-dominant wavelength measured after undeflected (effective length L=24 mm) and after deflection (effective length L=15 mm). Characteristic curve. It can be seen that under the operating conditions of 30 mA, the original dominant wavelength of the LED without external stress (L=24 mm) is 465.3 nm, while the LED of the deflection (L=15 mm) is the main The wavelength is 465.0 nm and its wavelength shift is only 0.3 nm. It is apparent that the LED produced by the present invention has excellent luminescence properties in the case of substrate deflection.
綜上所述,藉由異方性導電膠層28作為黏著層,可以簡化鍵合支持基板26的製程步驟,並且提供較佳的支持基板26鍵合方式,有利於剝離該轉換基板21步驟的進行,避免雷射剝離而導致的磊晶破碎現象。而且透過異方性導電膠層28的良好彈性,緩衝製程中的黏著壓力,進而提高製程良率、有效降低接觸電阻。再者,本發明的黏著作業 進行溫度為180℃以下,與習知晶片鍵合製程至少200℃以上的溫度相比,本發明為較低溫之製程,降低熱應力問題,可保有元件良好的光電特性。而且本發明採用較低之黏著壓力,亦有助於提升晶片鍵結之良率。同時,異方性導電膠層28的垂直導通及橫向絕緣的異方性導電特性,抑制了因電流於此路徑上擴散所增加的串聯阻值,因而有效提升元件之光電性能。In summary, by using the anisotropic conductive adhesive layer 28 as an adhesive layer, the process of bonding the support substrate 26 can be simplified, and a preferred bonding method of the support substrate 26 is provided, which facilitates the step of peeling off the conversion substrate 21. Perform to avoid the phenomenon of epitaxial fracture caused by laser peeling. Moreover, the good elasticity of the anisotropic conductive adhesive layer 28 buffers the adhesive pressure in the process, thereby improving the process yield and effectively reducing the contact resistance. Furthermore, the adhesive work of the present invention The temperature is 180 ° C or less, and the present invention is a lower temperature process than the conventional wafer bonding process at least 200 ° C or higher, which reduces the thermal stress problem and can maintain good photoelectric characteristics of the device. Moreover, the present invention uses a lower adhesive pressure and also helps to increase the bond yield of the wafer. At the same time, the vertical conduction of the anisotropic conductive adhesive layer 28 and the anisotropic conductive property of the lateral insulation suppress the series resistance increased by the current diffusion on the path, thereby effectively improving the photoelectric performance of the component.
惟以上所述者,僅為本發明之較佳實施例而已,當不能以此限定本發明實施之範圍,即大凡依本發明申請專利範圍及發明說明內容所作之簡單的等效變化與修飾,皆仍屬本發明專利涵蓋之範圍內。The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.
11~19‧‧‧步驟11~19‧‧‧Steps
21‧‧‧轉換基板21‧‧‧ Conversion substrate
22‧‧‧緩衝層22‧‧‧ Buffer layer
23‧‧‧發光單元23‧‧‧Lighting unit
231‧‧‧第一披覆層231‧‧‧First coating
232‧‧‧主動層232‧‧‧ active layer
233‧‧‧第二披覆層233‧‧‧Second coating
24‧‧‧金屬接觸層單元24‧‧‧Metal contact unit
241‧‧‧鎳金屬接觸層241‧‧‧ Nickel metal contact layer
242‧‧‧金金屬接觸層242‧‧‧ Gold metal contact layer
25‧‧‧附著反射層單元25‧‧‧Adhesive reflector unit
251‧‧‧鈦附著反射層251‧‧‧Titanium attached reflective layer
252‧‧‧鋁附著反射層252‧‧‧Aluminum attached reflective layer
253‧‧‧鈦附著反射層253‧‧‧Titanium attached reflective layer
254‧‧‧金附著反射層254‧‧‧ gold-attached reflective layer
26‧‧‧支持基板26‧‧‧Support substrate
27‧‧‧電極27‧‧‧Electrode
28‧‧‧異方性導電膠層28‧‧‧ anisotropic conductive adhesive layer
圖1是一個垂直式發光二極體(LED)的示意圖;圖2是本發明垂直式發光二極體之製造方法之一較佳實施例的步驟流程圖,該方法製造出圖1所示的垂直式發光二極體;圖3是該發光二極體於製作過程中的示意圖;圖4是一類似圖3的示意圖,顯示一轉換基板及一緩衝層被移除;圖5是該較佳實施例在進行雷射剝離製程後的試片俯視圖;圖6是本發明垂直式LED與傳統橫向LED的電流-電壓特性曲線圖;圖7是本發明垂直式LED與傳統橫向LED的光輸出功 率-電流特性曲線圖;及圖8是本發明垂直式LED於未撓曲狀態及撓曲狀態所測得的電流-主波長特性曲線圖。1 is a schematic view of a vertical light emitting diode (LED); FIG. 2 is a flow chart showing the steps of a preferred embodiment of the method for fabricating the vertical light emitting diode of the present invention, which produces the method shown in FIG. FIG. 3 is a schematic view of the light emitting diode during the manufacturing process; FIG. 4 is a schematic view similar to FIG. 3, showing a conversion substrate and a buffer layer being removed; FIG. 5 is a preferred embodiment. FIG. 6 is a current-voltage characteristic diagram of a vertical LED and a conventional lateral LED according to the present invention; FIG. 7 is a light output function of the vertical LED and the conventional lateral LED of the present invention; The rate-current characteristic graph; and FIG. 8 is a current-principal wavelength characteristic curve measured by the vertical LED of the present invention in an undeflected state and a flexed state.
11~19‧‧‧步驟11~19‧‧‧Steps
Claims (11)
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Title |
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Hon-Yi Kuo et al. , "Use of Elastic Conductive Adhesive as the Bonding Agent for the Fabrication of Vertical Structure GaN-based LEDs on Flexible Metal Substrate", IEEE Photonics Technology Letters, Vol. 20, No. 7, pp. 523-525 April 1, 2008. * |
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