200820464 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種發光元件及其製造方法。 【先前技術】 發光二極體(Light Emitting Diode ; LED)在高功率照 明之運用上，除了須持續提昇亮度外，散熱問題是另一' 亟須解決之主要問題。當發光二極體之光取出效率不佳 ( 時，無法穿出發光元件(發光二極體及其封裝體)之光線會 轉換為熱能。若無法有效地將此熱能導出發光元件，發 光二極體在操作時溫度會上昇，因而造成元件可靠性問 題。先前技藝為解決元件散熱問題，提出許多方法。例 如在以藍寶石基板成長氮化鎵糸列之發光二極體中，利 用二次轉移方式以雷射光照射或以化學蝕刻方式移除導 熱性較差之藍寶石基板，再結合一導熱性較佳之矽基 :板，以改善發光二極體之散熱效果。另—改善方式為以 覆晶接合(flip-chip bonding)取代傳統之導線接合(wke bonding)。圖1揭露一種習知以焊料(s〇lder)為焊接層 (soldering layer)之覆晶接合發光元件，包含一發光二^極體200820464 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a light-emitting element and a method of manufacturing the same. [Prior Art] In the application of high-power illumination, in addition to the need to continuously increase the brightness, the heat dissipation problem is another major problem that needs to be solved. When the light extraction efficiency of the light-emitting diode is not good (the light that cannot pass through the light-emitting element (the light-emitting diode and its package) is converted into heat energy. If the heat energy cannot be effectively derived from the light-emitting element, the light-emitting diode The temperature rises during operation, which causes component reliability problems. Previous techniques have been proposed to solve the problem of component heat dissipation. For example, in a light-emitting diode in which a sapphire substrate is grown in a gallium nitride array, a secondary transfer method is used. The sapphire substrate with poor thermal conductivity is removed by laser irradiation or chemical etching, and a heat-conducting ruthenium-based plate is combined to improve the heat dissipation effect of the light-emitting diode. The other way is to use flip-chip bonding ( Flip-chip bonding replaces conventional wire bonding. FIG. 1 discloses a conventional flip-chip bonding light-emitting element using a solder as a soldering layer, including a light-emitting diode.
一第一電極15、一第二電極16、 極15及第二電極16之上之第一: 18，用以在一接合製程中將第一 ^ 2〇，發光二極體10包含 、以及分別形成於第一電 焊接層17及第二焊接層 焊接層17及第二焊接層 6 200820464 18對應地接合於基座21上之第一接合墊22及第二接合 墊23上。焊接層17及18為具有低熔點之共熔合金 (eutectic alloy)。焊接層接合(s〇ider bonding)具有許多優 點，例如：具有低熔點之共熔合金可適用於低溫接合， 例如攝氏200至400度；再者，於接合時，熔融狀態町 確使焊接層覆蓋整個電極層表面，有效增加接合面積及 接合強度，使焊接層接合具有較純金屬接合如金-金接合a first electrode 18 on a first electrode 15, a second electrode 16, a pole 15 and a second electrode 16 for containing a first electrode, a light-emitting diode 10, and a separate portion in a bonding process The first electrical solder layer 17 and the second solder layer solder layer 17 and the second solder layer 6 200820464 18 are correspondingly bonded to the first bonding pad 22 and the second bonding pad 23 on the pedestal 21. The solder layers 17 and 18 are eutectic alloys having a low melting point. Solder layer bonding has many advantages, for example, a eutectic alloy having a low melting point can be applied to low temperature bonding, for example, 200 to 400 degrees Celsius; further, in the case of bonding, the molten state does cover the solder layer. The surface of the entire electrode layer effectively increases the joint area and joint strength, so that the solder joint is bonded to a pure metal joint such as a gold-gold joint.
(Gold_Gold Interconnection; GGI)更高之接合良率。另 外，使用焊接層接合無須以添加助熔劑⑴狀)辅助，玎避 免助熔劑殘留之污染風險。然而，焊接層接合卻會因接 合壓合時造成熔融之接合層擠出，甚至溢流至發光二極 體之側壁，造紐光疊狀p_n半導體層短路而使元件失 效。為解虹述之問題，美國專利號㈣觀㈣2提出 -改善之元件結構如圖2所示，發光元件包含一發光二 極體及-基座，發光二極體具有—p側電極^及一』 電極36，分別位於基板31之相對側，其中η㈣極36 上形成一接合塾38並連接至1線39 ; ρ侧電極35則 藉由-導電接合材# 37接合至基座，其中該導電接合材 料例如為焊料、導電樹脂、或銀膠。ρ侧電極％上之導 電接合材料37係形成-就，以避免於接合塵合時 擠出Ρ侧電極35之區域外而^型半導體層如及^ 7 200820464 半導體層333直接接觸，造成漏電流問題。 【發明内容】 本發明之一目的在提供一發光元件，除可有欵解' 述問題，並可增加接合面積，提高接合良率。 决上 本發明提供一發光元件，包含一發光二極體及〜 f 座。發光二極體包含一電極及形成於其上之一接合層^ 基座包含至少一接合墊及複數個凸起及/或凹陷形成=接 合墊上，其中，接合層之熔點較接合墊之熔點低。且該 等複數個凸起深入接合層至一深度，或接合層填入該等 複數個凹陷。 本發明之另一目的在提供一發光元件之製造方法，其 步驟包含提供一發光二極體包含一電極及形成於其上之 一接合層、提供一基座包含至少一接合墊、形成複數個 凸起及/或凹陷於接合墊上、以及接合該發光二極體及該 基座。 【實施方式】 請參考圖3A，依本發明之一發光元件包含一發光二 極體40及一基座單元50。發光二極體40包含一透明基 板 41 ’ 其材料例如為 Al2〇3、GaN、Glass、GaP、SiC、 8 200820464 或CVD鑽石；一第一接觸層42形成於透明基板41上， 第一接觸層42具有一第一區域a及一第二區域b;—發光 疊層43大致上形成於第一接觸層42上之第一區域a及 第二區域b，發光疊層依序包含一第一電性半導體層 431、一活性層（active layer) 432、及一第二電性半導體層 433，發光疊層43受電壓驅動時會發出光線，其材料可 為發出紅、黃、或綠色光線之(Α1ζΟ&1_ζ)0.5Ιη0.5Ρ四元系列， 或發出藍或紫色光線之AlxInyGa(1-x_y)N氮化鎵系列；一第 二接觸層44對應於第一區域a及第二區域b，形成於發 光疊層43上；一第一電極45對應於第一區域a，形成於 第二接觸層44上且覆蓋發光疊層43及第二接觸層44之 側壁；一第二電極46對應於第二區域b，形成於第二接 觸層44上；一第一接合層47形成於第一電極45之上、 及一第二接合層48形成於第二電極46之上。第一電極 45與第二電極46實質上在同一水平面上。第一接觸層 42與第二接觸層44之材質例如為氧化銦錫(ITO)透明導 電層；第一接合層47與第二接合層48為焊接層，其材 質包含金/錯、金/锡、錯/錫、或其他含錫或姻之合金。 基座單元50包含一基座51、一第一接合墊52及一 第二接合墊53形成於基座51上，用以分別與第一接合 層47及第二接合層48接合。其中，第一接合墊52及第 9 200820464 二接合塾53各包含複數個凸起及/或凹陷。於接合時，設 疋一接合溫度使接合層為溶融狀態，且使該等複數個凸 起深入接合層47及48至一深度，或使部份之接合層47 及48填入該等複數個凹陷。第一接合層47與第二接合 層48具有一厚度Η，且第一接合塾52與第二接合墊53 之凸起及/或凹陷具有一南低差h，例如接合墊上若僅具 有凸起或凹陷，則高低差為任一凸起凸出接合塾表面之 高度或任一凹陷凹陷於接合墊表面之深度；若接合墊上 同時具有凸起及凹陷，則高低差為任一相鄰之凸起之最 高點及凹陷之最低點之差值。於一較佳實施例，該厚度Η 大於或等於該高低差h。基座51係包含一導熱良好之材 質’例如為 Si、SiC、AIN、CuW、Cu、或 CVD 鑽石； 第一接合塾52或第一接合墊53包含金、銀、銅、|呂、 或具有溶點較接合層高之合金。 請參考圖3B ’發光二極體40係與基座單元5〇相接 合，接合方式例如為熱壓合(thermal-compr^sicm bonding)。接合層例如為20/80重量百分比之錫/金，其共 炫點（eutectic point)約為攝氏280度、接合墊為金，適當 之接合溫度約為攝氏300至400度，接合溫度之設定為 使接合層處於熔融狀態，但接合塾仍保持固態，亦即接 合溫度為大於接合層之熔點，但小於接合塾之溶點。於 200820464 加壓時’接合墊上之凸起深人接合層至—深度或部份之 接合層填人接合塾上之凹陷，以形成良好之接合。 办成接合墊上之凸起及/或凹陷之方法可以先在基 座51上形成-接合墊層，再以f知之微韻刻方式，敍 刻抽冰度之接合塾層，使凸起及/或凹陷一體成形於接 合墊52及接合墊53 ;於另一實施例，凸起及/或凹陷可 僅形成於接合塾52或接合塾53其中之―，凸起及/或凹 ，陷之表面圖案可為圓形、格子形、長條形、多邊形、或 其組合。 請參考圖4,其中顯示依本發明另一實施例之發光元 件’基座單元60包含一基座61、一第一接合墊62及一 第-接合墊63形成於基座51上、以及複數個微凸塊64 形成於第一接合墊62及第二接合墊63上。形成接合墊 上微凸塊之方法，可以先在基座61上分別形成第一接合 % 墊62及第二接合墊63,再沉積一金屬層於接合墊及基座 上，接著以習知之微影蝕刻方式，圖案化並蝕刻該金屬 層，使形成複數個微凸塊64於接合墊上；或者以剝除 (lift-off)方式先將圖案化之光阻層形成於金屬層下方，再 剝除光阻及光阻上方之金屬層以形成複數個微凸塊64於 接合墊上。微凸塊之表面圖案可為圓形、格子形、長條 形、多邊形、或其組合。其中該金屬層之材質包含金、 11 200820464 銀、銅、is、或具有熔點較接合層高之合金。 請參考圖5A及5B揭示本發明關於在基座上形成凸 起及/或凹陷之另一實施例。基座單元70包含一基座7卜 以及一第一接合墊72及一第二接合墊73形成於基座71 上。其中，基座71表面包含複數個凸起及/或凹陷，且第 一接合墊72及第二接合墊73係順應基座71上之凸起及 /或凹陷形狀形成於其上，使第一接合墊及第二接合墊表 面亦形成複數個凸起及/或凹陷。基座71上之凸起及/或 凹陷之形成，可於具有平坦表面之基座上直接以習知之 微影蝕刻方式或選擇性電鍍方式，圖案化該具有平坦表 面之基座，使形成複數個凸起及/或凹陷於該基座上。該 等複數個凸起及/或凹陷之表面圖案可為圓形、格子形、 長條形、多邊形、或其組合。基座71係包含一導熱良好 之材質，例如為Si、SiC、AIN、CuW、Cu、或CVD鑽 本發明之另一實施例亦可運用前述圖3至圖5所揭露 之發明原理，同時在接合墊及接合層上形成複數個凸起 及/或凹陷，如圖6A及6B所示，仍可逹到類似之接合效 果。 本發明所列舉之各實施例僅為用以說明本發明，並非 用以限制本發明之範圍。對本發明所作之任何修飾或變 12 200820464 更皆不脫離本發明之申請專利範圍。 【圖式簡單說明】 圖1為一示意圖，顯示依先前技藝之一發光元件； 圖2為一示意圖，顯示另一先前技藝之一發光元件； 圖3A及3B為示意圖，顯示依本發明第一實施例之一發光元 件； ， 圖4為一示意圖，顯示依本發明第二實施例之一發光元件； 圖5A及5B為示意圖，顯示依本發明第三實施例之一發光元 件； 圖6A及6B為示意圖，顯示依本發明第四實施例之一發光元 件0 【主要元件符號說明】 10、 40、80 :發光二極體； 11、 31、41 :透明基板； 2卜 39、51、61、71 :基座； 13、33、43 :發光疊層； 15、 35、45 :第一電極； 16、 36、46 :第二電極； 17、 47、87 ··第一接合層； 18、 48、88 :第二接合層； 13 200820464 20、50、60、70 :基座單元； 22、 52、62、72 :第一接合墊； 23、 53、63、73 ··第二接合墊； 321、431 :第一電性半導體層； 323、433 :第二電性半導體層； 37 :導電接合材料； 42 :第一接觸層； ， 432 :活性層； 44 :第二接觸層； 64 :微凸塊。(Gold_Gold Interconnection; GGI) Higher bond yield. In addition, the use of solder joint bonding does not require the addition of a flux (1) to assist in avoiding the risk of contamination of the flux residue. However, the bonding of the solder layer may cause the molten bonding layer to be extruded due to the bonding, or even overflow to the sidewall of the light-emitting diode, and the germanium photonic laminated p_n semiconductor layer is short-circuited to cause the component to fail. In order to solve the problem of the rainbow, U.S. Patent No. (4) (4) 2 proposes that the improved component structure is as shown in FIG. 2, the light-emitting component comprises a light-emitting diode and a pedestal, and the light-emitting diode has a -p-side electrode and an electrode. 36, respectively located on the opposite side of the substrate 31, wherein an 塾38 is formed on the η (tetra) pole 36 and connected to the 1 line 39; the ρ side electrode 35 is bonded to the pedestal by the conductive bonding material #37, wherein the conductive bonding material For example, solder, conductive resin, or silver paste. The conductive bonding material 37 on the ρ side electrode % is formed - in order to avoid directing contact of the semiconductor layer such as the semiconductor layer 333 with the semiconductor layer 333 when the bonding is performed, and causing leakage current. problem. SUMMARY OF THE INVENTION An object of the present invention is to provide a light-emitting element which can improve the bonding area and improve the bonding yield, in addition to the problem described. Summary of the Invention The present invention provides a light-emitting element comprising a light-emitting diode and a ~f block. The light-emitting diode includes an electrode and a bonding layer formed thereon. The pedestal comprises at least one bonding pad and a plurality of protrusions and/or depressions formed on the bonding pad, wherein the bonding layer has a lower melting point than the bonding pad. . And the plurality of protrusions penetrate the bonding layer to a depth, or the bonding layer fills the plurality of depressions. Another object of the present invention is to provide a method for fabricating a light-emitting device, the method comprising the steps of: providing a light-emitting diode comprising an electrode and a bonding layer formed thereon, providing a substrate comprising at least one bonding pad, forming a plurality of Projecting and/or recessing on the bonding pad, and bonding the LED and the pedestal. [Embodiment] Referring to FIG. 3A, a light-emitting element according to the present invention comprises a light-emitting diode 40 and a base unit 50. The light emitting diode 40 includes a transparent substrate 41 ′ such as Al 2 〇 3, GaN, Glass, GaP, SiC, 8 200820464 or CVD diamond; a first contact layer 42 is formed on the transparent substrate 41, the first contact layer 42 has a first area a and a second area b; the light emitting layer 43 is formed substantially on the first area a and the second area b on the first contact layer 42, and the light emitting layer sequentially comprises a first electric The semiconductor layer 431, an active layer 432, and a second electrical semiconductor layer 433, the light-emitting layer 43 emits light when driven by a voltage, and the material may emit red, yellow, or green light ( Α1ζΟ&1_ζ)0.5Ιη0.5Ρ quaternary series, or AlxInyGa(1-x_y)N gallium nitride series emitting blue or purple light; a second contact layer 44 corresponding to the first region a and the second region b, forming On the light-emitting layer 43; a first electrode 45 corresponding to the first region a is formed on the second contact layer 44 and covers the sidewalls of the light-emitting layer 43 and the second contact layer 44; a second electrode 46 corresponds to the first layer a second region b formed on the second contact layer 44; a first bonding layer 47 formed on the second An electrode 45 and a second bonding layer 48 are formed over the second electrode 46. The first electrode 45 and the second electrode 46 are substantially at the same level. The material of the first contact layer 42 and the second contact layer 44 is, for example, an indium tin oxide (ITO) transparent conductive layer; the first bonding layer 47 and the second bonding layer 48 are solder layers, and the material thereof comprises gold/wrong, gold/tin. , wrong / tin, or other alloys containing tin or marriage. The base unit 50 includes a base 51, a first bonding pad 52, and a second bonding pad 53 formed on the base 51 for engaging the first bonding layer 47 and the second bonding layer 48, respectively. The first bonding pad 52 and the ninth 200820464 two bonding pads 53 each include a plurality of protrusions and/or depressions. In the bonding, the bonding temperature is set such that the bonding layer is in a molten state, and the plurality of protrusions are deepened into the bonding layers 47 and 48 to a depth, or a part of the bonding layers 47 and 48 are filled in the plurality of bonding layers. Depression. The first bonding layer 47 and the second bonding layer 48 have a thickness Η, and the protrusions and/or depressions of the first bonding pad 52 and the second bonding pad 53 have a south-lower difference h, for example, if there is only a bump on the bonding pad Or depression, the height difference is the height of any convex protrusion joint surface or the depth of any depression depression on the surface of the bonding pad; if the bonding pad has both protrusions and depressions, the height difference is any adjacent convex The difference between the highest point and the lowest point of the depression. In a preferred embodiment, the thickness Η is greater than or equal to the height difference h. The susceptor 51 comprises a material having good thermal conductivity, such as Si, SiC, AIN, CuW, Cu, or CVD diamond; the first bonding pad 52 or the first bonding pad 53 comprises gold, silver, copper, ly, or has An alloy with a higher melting point than the bonding layer. Referring to Fig. 3B, the light-emitting diode 40 is bonded to the base unit 5, and the bonding method is, for example, thermal-compr^sicm bonding. The bonding layer is, for example, 20/80 weight percent tin/gold, the eutectic point is about 280 degrees Celsius, the bonding pad is gold, and the proper bonding temperature is about 300 to 400 degrees Celsius, and the bonding temperature is set to The bonding layer is brought into a molten state, but the bonding crucible remains solid, that is, the bonding temperature is greater than the melting point of the bonding layer, but less than the melting point of the bonding crucible. At 200820464, the raised deep joint layer on the bond pad to the depth or portion of the bond layer fills the recess on the joint to form a good bond. The method of forming the protrusions and/or depressions on the bonding pads may first form a bonding pad layer on the susceptor 51, and then engrave the entanglement layer of the ice-splitting degree to make the bulge and/or Or the recess is integrally formed on the bonding pad 52 and the bonding pad 53; in another embodiment, the protrusion and/or the recess may be formed only on the bonding pad 52 or the bonding pad 53, the protrusion and/or the concave surface. The pattern can be circular, lattice, elongated, polygonal, or a combination thereof. Please refer to FIG. 4, which shows a light-emitting element according to another embodiment of the present invention. The base unit 60 includes a base 61, a first bonding pad 62 and a first bonding pad 63 formed on the base 51, and a plurality of The micro bumps 64 are formed on the first bonding pads 62 and the second bonding pads 63. The method of forming the micro bumps on the bonding pad may first form a first bonding % pad 62 and a second bonding pad 63 on the pedestal 61, and then deposit a metal layer on the bonding pad and the pedestal, followed by a conventional lithography. Etching, patterning and etching the metal layer to form a plurality of microbumps 64 on the bonding pad; or forming a patterned photoresist layer under the metal layer in a lift-off manner, and then stripping The metal layer over the photoresist and photoresist forms a plurality of microbumps 64 on the bond pads. The surface pattern of the microbumps may be circular, lattice, elongated, polygonal, or a combination thereof. The material of the metal layer comprises gold, 11 200820464 silver, copper, is, or an alloy having a higher melting point than the bonding layer. Referring to Figures 5A and 5B, another embodiment of the present invention relating to the formation of protrusions and/or depressions on a pedestal is disclosed. The base unit 70 includes a base 7 and a first bonding pad 72 and a second bonding pad 73 formed on the base 71. The surface of the pedestal 71 includes a plurality of protrusions and/or depressions, and the first bonding pad 72 and the second bonding pad 73 are formed on the pedestal 71 with a convex and/or concave shape, so that the first A plurality of protrusions and/or depressions are also formed on the surface of the bonding pad and the second bonding pad. The protrusions and/or depressions formed on the pedestal 71 can be patterned on the pedestal having a flat surface by a conventional lithography or selective plating method to pattern the pedestal having a flat surface to form a plurality of pedestals. Raised and/or recessed on the base. The surface pattern of the plurality of protrusions and/or depressions may be circular, lattice, elongated, polygonal, or a combination thereof. The pedestal 71 comprises a material with good thermal conductivity, such as Si, SiC, AIN, CuW, Cu, or CVD. Another embodiment of the invention can also apply the inventive principles disclosed in the foregoing FIGS. 3 to 5, and A plurality of protrusions and/or depressions are formed on the bonding pads and the bonding layer, and as shown in FIGS. 6A and 6B, a similar bonding effect can be obtained. The examples of the invention are intended to be illustrative only and not to limit the scope of the invention. Any modification or variation of the present invention will not be devised from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a light-emitting element according to the prior art; FIG. 2 is a schematic view showing another light-emitting element of the prior art; FIGS. 3A and 3B are schematic views showing the first according to the present invention. FIG. 4 is a schematic view showing a light-emitting element according to a second embodiment of the present invention; FIGS. 5A and 5B are schematic views showing a light-emitting element according to a third embodiment of the present invention; FIG. 6B is a schematic view showing a light-emitting element 0 according to a fourth embodiment of the present invention. [Description of main component symbols] 10, 40, 80: light-emitting diodes; 11, 31, 41: transparent substrate; 2, 39, 51, 61 , 71: pedestal; 13, 33, 43: light-emitting laminate; 15, 35, 45: first electrode; 16, 36, 46: second electrode; 17, 47, 87 · · first bonding layer; 48, 88: second bonding layer; 13 200820464 20, 50, 60, 70: base unit; 22, 52, 62, 72: first bonding pad; 23, 53, 63, 73 · · second bonding pad; 321 , 431 : first electrical semiconductor layer; 323, 433 : second electrical semiconductor layer; 37 : conductive bonding material ; 42: a first contact layer; 432: an active layer; 44: second contact layer; 64: micro bumps.