200832645 22160twf.doc/n 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種凸塊結構及其製造方法，且特別 是有關於一種多層凸塊結構及其製造方法。 【先前技術】 ^ 覆晶接合技術（flip chip interconnect techn〇1〇gy)乃 鲁 是一種將晶片（die)連接至一線路板的封裝技術，其主要 是在晶片之多個接墊上形成多個凸塊（bump)。接著將晶 片翻轉（flip)，並利用這些凸塊來將晶片的這些接墊連接 至線路板上的接合墊（terminal)，以使得晶片可經由這些 凸塊而電性連接至電路板或其他承載器上。通常，凸塊具 有若干種類型，例如焊料凸塊、金凸塊、銅凸塊、導電^ 分子凸塊、高分子凸塊等。 圖1A為習知的金凸塊的剖面圖，而圖1β為習知的金 凸塊的俯視圖。請參考圖1A與圖1B，習知的金凸塊結構 馨 適於配置在一晶片110上，而此晶片110上已形成有多個 鋁接墊120 (圖1A與圖1B僅繪示一個鋁接墊）與一保護 層130。其中，保濩層13〇具有多個開口 ，其分別暴 路各銘接塾120的-部份。此外，習知的金凸塊結構包括 一球底金屬層140與一金凸塊15〇，其中球底金屬層14〇 配置開口 130a内，並覆蓋部分保護層13〇。金凸塊15〇配 置於球底金屬層140上。由於此金凸塊15〇覆蓋於部分保 護層130上方的球底金屬層14〇上，因此金凸塊15〇具有 200832645 L,iN-y juyui>4 22160twf.doc/n 一％狀凸起部150a，而這就所謂城牆效應（wall effect)。 然而，此環狀凸起部150a會影響金凸塊150與其他承載器 (未繪示）之間的接合強度。此外，由於球底金屬層14〇 僅配置於金凸塊150的下方，因此當球底金屬層140與金 凸塊150之間或是球底金屬層140與保護層130之間產生 裂缝時’此種習知的金凸塊結構便容易出現底切效應 (under cut effect)。 此外，由於金凸塊150必須具有相當的高度，以便於 電性連接至電路板或其他承載器，然而金凸塊150的高度 越高則製造成本越高。 【發明内容】 本發明提供一種多層凸塊結構的製造方法，以改善城 牆效應。 本發明提供一種多層凸塊結構，以降低製造成本。 本發明提出一種多層凸塊結構的製造方法，其包括下 列步驟。首先，提供一基板，而此基板具有多個接墊與一 保，層。其中，保護層具有多個第一開口，且各第一開口 暴露出接墊之一部分。在保護層上形成一第一圖案化光阻 層，其中第一圖案化光阻層具有多個第二開口，且各第二 ^ 口暴露出各接墊之-部分。在這些第二開口_成多個 ，二凸塊。在基板上方形成一第一球底金屬材料層，以覆 盖第-圖案化光阻層與第_凸塊。在第一凸塊上方之第一 球底金屬材料層上形成多個第二凸塊，其中第_凸塊與第 6 200832645 ijn-y j 22160twf.doc/n 一凸塊的材質不同。圖案化第一球底金屬材料層，以形成 多個第一球底金屬層。移除第一圖案化光阻層。 在本發明之一實施例中，形成第二凸塊的步驟更包括 在第一球底金屬材料層上形成一第二圖案化光阻層，且第 二圖案化光阻層具有多個第三開口，其分別暴露出這些第 一凸塊上方之第一球底金屬材料層。在第二開口内形成第 二凸塊。移除第二圖案化光阻層。 籲在本發明之一實施例中，形成球底金屬層的步驟包栝 以第二凸塊為遮罩，圖案化第一球底金屬材料層，以形成 第一球底金屬層。 在本發明之一實施例中，第一凸塊為鋁凸塊，而第二 凸塊為金凸塊。 士在本發明之一實施例中，接墊與第一凸塊的材質不同 日守，在形成第一圖案化光阻層之前，多層凸塊結構的製造 去更包括在保護層上形成—第二球底金屬材料層，以慕 *第口所暴露出之接墊，且在移除第一圖案化光阻廣 之後更包括圖案化第二球底金屬材料層，以形成多個第 二球底金屬層。 在本發明之—實施例中，形成第二球底金屬層之步驊 包括在保護層上形成一第三圖案化光阻層。以第三圖案化 光阻層為遮罩’圖案化第二球底金屬材料層，以形成第> 球底金屬層。移除該第三_化光阻層。 本發明提出—種多層凸塊結構，其適於配置於一基板 上’而基板具有一接塾與一保護層，其中保護層具有一第 7 200832645 K,L\-yj\jyyjKj4 22160twf.doc/n 一開口，且第一開口暴露出接墊之一部分。此多層凸塊結 構包括一第一凸塊、一第一球底金屬層與第二凸塊，其中 第一凸塊配置於第一開口内，並與接墊電性連接。第_球 底金屬層配置於該第一凸塊上，而第二凸塊配置於第一球 底金屬層上。 在本發明之一實施例中，第一凸塊的面積小於第一開 口的面積。 在本發明之一實施例中，第二凸塊的面積小於或等於 第一凸塊的面積。 在本發明之一實施例中，第一凸塊為鋁凸塊，而第二 凸塊為金凸塊。 在本發明之一實施例中，多層凸塊結構更包括一第二 球底金屬層’其配置於第—開σ内，並位於接墊 塊之間。 在本發明之-實施例中，基板包括晶片或晶圓。 …基於上述，由於本發日麟衫層凸塊結構以取代習知 的早層凸塊，因此當本發_多層凸塊 •時、發明的多層凸塊結 找成本。此外，由於第—凸塊戦於賴 内’因此此種多層凸塊結構具有平坦的頂面。開 【實施方式】 8 200832645 ui\-y3uyuu4 22160twf.doc/n 第一實施例 圖2A至圖2D為本發明之第一實施例之-種多層凸 塊結構的製造方法的示意圖。請先參考圖2A，本實施^之 多層凸塊結構的製造方法包括下列步驟。首先，提供一基 板210，而基板210具有多個接墊22〇與一保護層23〇，其 中保護層230具有多個第一開口 23〇a，且各第一開口 分別暴露出相對應之接墊220之一部分。值得注意的是， 為了便於說明’本實施例的開口 230a與接墊220均僅繪示 一個。此外，此基板210可以是晶圓或是其他承載器:而 接墊220的材質可以是鋁、銅或是其他金屬。 請繼續參考圖2A，在保護層230上形成一第一圖案 化光阻層410，其中第一圖案化光阻層41〇具有多個第二 開口 410a，且各第二開口 410a暴露出相對應的接墊22〇 之一部分。值得注意的是，第二開口 410a小於接塾220 以及第一開口 230a。然後，在第二開口 410a内形成第一 凸塊310。換言之，在保護層230所暴露出之接墊220上 形成多個第一凸塊310。此外，形成第一凸塊310的方法 可以是電鍍製程。在本實施例中，第一凸塊310為鋁凸塊。 然而，在其他實施例中，第一凸塊310也可以是其他金屬 材質。 請繼續參考圖2A，在基板210上方形成一第一球底 金屬材料層320，以覆蓋第一圖案化光阻層410與第一凸 塊310。此外，形成第一球底金屬材料層320的方法可以 是濺鍍製程、物理氣相沈積製程或化學氣相沈積製程。 9 200832645 22160twf. doc/nBACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a bump structure and a method of fabricating the same, and more particularly to a multilayer bump structure and a method of fabricating the same. [Prior Art] ^ Flip chip interconnect technology (flip chip interconnect techn〇1〇gy) is a packaging technology for connecting a die to a circuit board, which is mainly formed on a plurality of pads of the wafer. Bump. The wafers are then flipped and the bumps are used to connect the pads of the wafer to the terminals on the board such that the wafers can be electrically connected to the board or other carrier via the bumps. On the device. Generally, bumps have several types, such as solder bumps, gold bumps, copper bumps, conductive bumps, polymer bumps, and the like. 1A is a cross-sectional view of a conventional gold bump, and FIG. 1β is a top view of a conventional gold bump. Referring to FIG. 1A and FIG. 1B, a conventional gold bump structure is suitably disposed on a wafer 110, and a plurality of aluminum pads 120 have been formed on the wafer 110 (FIG. 1A and FIG. 1B only show one aluminum). Pad) and a protective layer 130. Among them, the protective layer 13 has a plurality of openings, and each of the storm paths is connected to the portion of the 120. In addition, the conventional gold bump structure includes a ball bottom metal layer 140 and a gold bump 15〇, wherein the ball bottom metal layer 14 is disposed in the opening 130a and covers a portion of the protective layer 13A. The gold bumps 15 are disposed on the ball metal layer 140. Since the gold bump 15 〇 covers the ball metal layer 14 上方 above the partial protective layer 130, the gold bump 15 〇 has 200832645 L, iN-y juyui > 4 22160 twf. doc / n a % convex portion 150a, and this is called the wall effect. However, this annular projection 150a affects the strength of the joint between the gold bump 150 and other carriers (not shown). In addition, since the ball bottom metal layer 14 is disposed only under the gold bump 150, when a crack occurs between the ball bottom metal layer 140 and the gold bump 150 or between the ball bottom metal layer 140 and the protective layer 130' Such a conventional gold bump structure is prone to an undercut effect. In addition, since the gold bumps 150 must have a relatively high height to facilitate electrical connection to a circuit board or other carrier, the higher the height of the gold bumps 150, the higher the manufacturing cost. SUMMARY OF THE INVENTION The present invention provides a method of fabricating a multilayer bump structure to improve wall effects. The present invention provides a multilayer bump structure to reduce manufacturing costs. The present invention proposes a method of fabricating a multilayer bump structure comprising the following steps. First, a substrate is provided, and the substrate has a plurality of pads and a layer. Wherein the protective layer has a plurality of first openings, and each of the first openings exposes a portion of the pads. A first patterned photoresist layer is formed on the protective layer, wherein the first patterned photoresist layer has a plurality of second openings, and each of the second openings exposes a portion of each of the pads. In these second openings _ into multiple, two bumps. A first layer of bottom metal material is formed over the substrate to cover the first patterned photoresist layer and the first bump. A plurality of second bumps are formed on the first ball metal material layer above the first bump, wherein the first bump is different from the material of the sixth bump. The first ball-bottom metal material layer is patterned to form a plurality of first ball-bottom metal layers. The first patterned photoresist layer is removed. In an embodiment of the invention, the step of forming the second bump further comprises forming a second patterned photoresist layer on the first ball-bottom metal material layer, and the second patterned photoresist layer has a plurality of third An opening that exposes the first layer of bottom metal material above the first bumps, respectively. A second bump is formed in the second opening. The second patterned photoresist layer is removed. In an embodiment of the invention, the step of forming a ball-bottom metal layer is performed by masking the second bump as a mask to pattern the first ball-bottom metal material layer to form a first ball-bottom metal layer. In one embodiment of the invention, the first bump is an aluminum bump and the second bump is a gold bump. In an embodiment of the present invention, the pad is different from the material of the first bump, and before the first patterned photoresist layer is formed, the fabrication of the multi-layer bump structure further includes forming on the protective layer. a second ball metal material layer, which is exposed by the mouth of the mouth, and further includes a patterned second ball bottom metal material layer after removing the first patterned photoresist to form a plurality of second balls Bottom metal layer. In an embodiment of the invention, the step of forming the second ball-bottom metal layer includes forming a third patterned photoresist layer on the protective layer. The second patterned bottom metal material layer is patterned with the third patterned photoresist layer as a mask to form a > ball bottom metal layer. The third _ photoresist layer is removed. The present invention provides a multilayer bump structure suitable for being disposed on a substrate. The substrate has an interface and a protective layer, wherein the protective layer has a 7200832645 K, L\-yj\jyyjKj4 22160twf.doc/ n an opening, and the first opening exposes a portion of the pad. The multi-layer bump structure includes a first bump, a first ball bottom metal layer and a second bump, wherein the first bump is disposed in the first opening and electrically connected to the pad. The first bottom metal layer is disposed on the first bump, and the second bump is disposed on the first bottom metal layer. In an embodiment of the invention, the area of the first bump is smaller than the area of the first opening. In an embodiment of the invention, the area of the second bump is less than or equal to the area of the first bump. In one embodiment of the invention, the first bump is an aluminum bump and the second bump is a gold bump. In one embodiment of the invention, the multilayer bump structure further includes a second bottom metal layer ' disposed within the first opening σ and located between the pads. In an embodiment of the invention, the substrate comprises a wafer or wafer. ... Based on the above, since the conventional cymbal layer bump structure replaces the conventional early layer bump, the present invention has a cost of the multilayer bump. Further, since the first bump is in the inner portion, the multilayer bump structure has a flat top surface. [Embodiment] 8 200832645 ui\-y3uyuu4 22160twf.doc/n First Embodiment Fig. 2A to Fig. 2D are schematic views showing a method of manufacturing a multilayered bump structure according to a first embodiment of the present invention. Referring first to Figure 2A, the method of fabricating the multilayer bump structure of the present embodiment includes the following steps. First, a substrate 210 is provided, and the substrate 210 has a plurality of pads 22 and a protective layer 23, wherein the protective layer 230 has a plurality of first openings 23〇a, and each of the first openings is exposed to a corresponding one. One part of the pad 220. It should be noted that, for convenience of explanation, only one opening 230a and the pad 220 of the present embodiment are shown. In addition, the substrate 210 can be a wafer or other carrier: and the pad 220 can be made of aluminum, copper or other metals. Referring to FIG. 2A, a first patterned photoresist layer 410 is formed on the protective layer 230, wherein the first patterned photoresist layer 41 has a plurality of second openings 410a, and each of the second openings 410a is exposed correspondingly. One of the pads 22 〇. It is to be noted that the second opening 410a is smaller than the interface 220 and the first opening 230a. Then, a first bump 310 is formed in the second opening 410a. In other words, a plurality of first bumps 310 are formed on the pads 220 exposed by the protective layer 230. Further, the method of forming the first bumps 310 may be an electroplating process. In this embodiment, the first bumps 310 are aluminum bumps. However, in other embodiments, the first bumps 310 may also be other metal materials. Referring to FIG. 2A, a first layer of bottom metal material 320 is formed over the substrate 210 to cover the first patterned photoresist layer 410 and the first bumps 310. Further, the method of forming the first ball-bottom metal material layer 320 may be a sputtering process, a physical vapor deposition process, or a chemical vapor deposition process. 9 200832645 22160twf. doc/n
請參考圖2B，在第一球底金屬材料層320上形成一 第二圖案化光阻層420，且第二圖案化光阻層420具有多 個第三開口 420a，其分別暴露出第一凸塊310上方之第一 球底金屬材料層320。在本實施例中，第三開口 420a的直 徑等於第二開口 410a的直徑。然而，在其他本實施例中， 第三開口 420a的直徑也可以大於或小於第二開口 410a的 直徑。然後，在這些第三開口 420a形成多個第二凸塊330, 且第一凸塊310與第二凸塊330的材質不同。此外，形成 第二凸塊330的方法可以是電鍍製程。在本實施例中，第 二凸塊330為金凸塊。然而，在其他實施例中，第二凸塊 330也可以是其他金屬，且第一凸塊31〇與第二凸塊mo 的材質不同。 請麥考圖2B與圖2C，然後，移除第二圖案化光阻層 42〇 ’以暴露出第二凸塊33〇。此外，第二凸塊33〇的頂面 330a為平面。然後，以第二凸塊33〇為遮罩進行一蝕刻製 程，移除部分第-球底金屬材料層32G，以形成第一球底 金屬層322。 一 研茶考圖2D，然後，移除第一圖案化光阻層41〇。至 此’大致完成本實補之多層凸塊結構謂的製造流程。 此卜在移除第—圖案化光阻層41Q之後，也可以對於基 板MO進行一切割製程，以形成多個晶片結構（未繪示)土。 以下將就此夕層凸塊結構獅的細部結構進行說明。 俯親：5為^發明之第一實施例之一種多層凸塊結構的 俯視圖、參考圖犯，此多層凸塊結構適於配置於一 200832645 v^in-^ juy u04 22160twf.doc/n 基板210上。此基板210具有一接墊220與一保護層230， 其中保護層230具有一第一開口 230a，其暴露出接胃墊22〇 之一部分。此外，基板210可以是晶片或晶圓。此多層凸 境結構300包括第一凸塊310、一第一球底金屬層322與 一第二凸塊330，其中第一凸塊31〇配置於第一開口 23〇a 内，並位於保護層230所暴露出之接墊22〇上。此外，第 一凸塊310與接墊220電性連接，而第一凸塊31〇的底面 積小於第一開口 230a的底面積。第一球底金屬層322配置 於第一凸塊310上，而第二凸塊330配置於第一球底金屬 層322上。再者，第二凸塊330的頂面330a為平面。在本 貫施例中，第二凸塊330的面積等於第一凸塊31〇的面積。 然而，在其他實施例中，第二凸塊330的面積也可以是小 於或大於第一凸塊310的面積。 由於第一凸塊310形成於保護層230的第一開口 230a 内’且第一凸塊310的底面積小於第一開口 230a的底面 積’因此形成於第一凸塊310上之第二凸塊330具有平坦 的頂面330a ’以改善習知技術所具有的城牆效應。此外， 當第二凸塊330為金凸塊時，相較於習知技術使用單一材 質的凸塊，本實施例採用第一凸塊310 (例如是鋁凸塊） 與第二凸塊330 (例如是金凸塊）將具有較低的製造成本。 另二實施例 圖3A至圖3F為本發明之第二實施例之一種多層凸塊 結構的製造方法的示意圖。請參考圖3A，本實施例與第一 11 200832645 ujN-yDuyuu4 22160twf.doc/n 實施例相似’其不同之處在於··當接墊220與隨後所欲形 成的第一凸塊310的材質為不同時，在形成第一圖案化光 阻層410之；，先在保濩層230上形成一第二球底金屬材 料層340，以覆蓋第一開口 230a所暴露出之接墊22〇。舉 例而言，當接墊220的材質為鋁，而第一凸塊31〇的材& 不是鋁時，在接墊220上需形成第二球底金屬材料層34〇。 形成弟一球底金屬材料層340的方法可以是錢鍍製程、物 理氣相沈積製程或化學氣相沈積製程。然後，才依序形成 響 第一圖案化光阻層410與第一凸塊31〇。 乂 請簽考圖3B至圖3D，圖3B至圖3D所繪示的内容 與圖2B至圖2D所繪示的内容。更詳細而言，依序形成第 一球底金屬材料層340、弟二圖案化光阻層420與第二凸 塊330。然後，移除第二圖案化光阻層42〇與圖案化第一 球底金屬材料層340。再來，移除第一圖案化光阻層41〇。 請參考圖3E與3F，在保護層230上形成一第三圖案 化光阻層430 ’且弟二圖案化光阻層430覆蓋第二凸塊330 _ 與第一凸塊310。然後，以第三圖案化光阻層43〇為遮罩， 圖案化第二球底金屬材料層340,以形成第二球底金屬層 342 〇 請參考圖3F，移除第三圖案化光阻層34〇。至此，大 致完成本實施例之多層凸塊結構30〇a的製造流程。此外， 在移除第三圖案化光阻層430之後，也可以對於基板210 進行一切割製程，以形成多個晶片結構（未繪示）。以下 將就此多層凸塊結構300a的細部結構進行說明。 12 200832645 oiN-y3u^ui>4 22160twf. doc/n 、0 3P H發％之第二實施例之_種多層凸塊結構的 俯視圖。請參考圖3F，此多層凸塊結構3GGa與第-實施 例相似，其不同之處在於··當接墊22〇與第一凸塊31〇的 材貝為不㈣’多層凸塊結構3⑽a更包括—第二球底金屬 層342，其配置於第一開口 230a内，並位於接墊22〇盘第 一凸塊310之間。 ’、 〜雖然本發明已以較佳實施例揭露如上，然其 限定本發明，任何所屬技術領域中具有通常知識者 ，離本發明之精神和範_，t可作些許之更動=德 =本發明之保護範圍當視後附之申請專利範崎ς定者 【圖式簡單說明】 圖1Α為習知的金凸塊的剖面圖。 圖1Β為習知的金凸塊的俯視圖。 應 圖2Α至圖2D $本發明之一實施例之一種夕s • 結構的製造方法的示意圖。 夕層凸塊 圖3A至圖3F為本發明之第二實施 結構的製造方法的示意圖。 種夕層凸塊 【主要元件符號說明】 110 ·晶片 120 :鋁接墊 130 :保護層 13 22160twf.doc/n 200832645 130a :開口 140 :球底金屬層 150 :金凸塊 150a :環狀凸起部 210 :基板 220 :接墊 230 ··保護層 230a :第一開口 ⑩ 300 :多層凸塊結構 310 :第一凸塊 320 :第一球底金屬材料層 322 :第一球底金屬層 330 :第二凸塊 330a :頂面 340 :第二球底金屬材料層 342 :第二球底金屬層 • 410 :第一圖案化光阻層 410 a :第二開口 420 :第二圖案化光阻層 420a :第三開口 430 :第一圖案化光阻層 14Referring to FIG. 2B, a second patterned photoresist layer 420 is formed on the first ball-bottom metal material layer 320, and the second patterned photoresist layer 420 has a plurality of third openings 420a respectively exposing the first bumps. A first layer of bottom metal material 320 over the block 310. In the present embodiment, the diameter of the third opening 420a is equal to the diameter of the second opening 410a. However, in other embodiments, the diameter of the third opening 420a may also be larger or smaller than the diameter of the second opening 410a. Then, a plurality of second bumps 330 are formed on the third openings 420a, and the materials of the first bumps 310 and the second bumps 330 are different. Further, the method of forming the second bumps 330 may be an electroplating process. In this embodiment, the second bump 330 is a gold bump. However, in other embodiments, the second bump 330 may be other metal, and the first bump 31 is different from the material of the second bump mo. Please take McCaw 2B and FIG. 2C, and then remove the second patterned photoresist layer 42A' to expose the second bumps 33A. Further, the top surface 330a of the second bump 33A is a flat surface. Then, an etching process is performed by using the second bump 33 as a mask, and a portion of the first-ball-bottom metal material layer 32G is removed to form a first ball-bottom metal layer 322. A tea study FIG. 2D, and then the first patterned photoresist layer 41 is removed. So far, the manufacturing process of the multi-layered bump structure of the actual complement is completed. After the first patterned photoresist layer 41Q is removed, a cutting process may be performed on the substrate MO to form a plurality of wafer structures (not shown). The detailed structure of the lion of the ridge layer structure will be described below. The prosthesis: 5 is a top view of a multilayer bump structure of the first embodiment of the invention, and the reference bump is configured to be disposed on a substrate 202210. on. The substrate 210 has a pad 220 and a protective layer 230. The protective layer 230 has a first opening 230a that exposes a portion of the stomach pad 22A. Further, the substrate 210 may be a wafer or a wafer. The multi-layered convex structure 300 includes a first bump 310, a first ball bottom metal layer 322 and a second bump 330. The first bump 31 is disposed in the first opening 23〇a and is located on the protective layer. 230 exposed pads 22 〇. In addition, the first bump 310 is electrically connected to the pad 220, and the bottom surface of the first bump 31 is smaller than the bottom area of the first opening 230a. The first ball bottom metal layer 322 is disposed on the first bump 310, and the second bump 330 is disposed on the first ball bottom metal layer 322. Furthermore, the top surface 330a of the second bump 330 is a flat surface. In the present embodiment, the area of the second bump 330 is equal to the area of the first bump 31A. However, in other embodiments, the area of the second bumps 330 may also be smaller or larger than the area of the first bumps 310. Since the first bump 310 is formed in the first opening 230a of the protective layer 230 and the bottom area of the first bump 310 is smaller than the bottom area of the first opening 230a, the second bump formed on the first bump 310 is formed. 330 has a flat top surface 330a' to improve the wall effect that conventional techniques have. In addition, when the second bumps 330 are gold bumps, the first bumps 310 (for example, aluminum bumps) and the second bumps 330 are used in this embodiment. For example, gold bumps) will have lower manufacturing costs. SECOND EMBODIMENT Figs. 3A to 3F are views showing a method of manufacturing a multilayer bump structure according to a second embodiment of the present invention. Referring to FIG. 3A, the present embodiment is similar to the first embodiment of the first 11 200832645 ujN-yDuyuu 4 22160 twf.doc/n. The difference is that when the pad 220 and the subsequently formed first bump 310 are made of a material At the same time, in the first patterned photoresist layer 410, a second ball-bottom metal material layer 340 is formed on the protective layer 230 to cover the pads 22 暴露 exposed by the first opening 230a. For example, when the material of the pad 220 is aluminum, and the material of the first bump 31 is not aluminum, a second layer of bottom metal material 34 is formed on the pad 220. The method of forming the core-bottom metal material layer 340 may be a vacuum plating process, a physical vapor deposition process, or a chemical vapor deposition process. Then, the first patterned photoresist layer 410 and the first bump 31 are sequentially formed.乂 Please refer to FIG. 3B to FIG. 3D, the contents illustrated in FIGS. 3B to 3D and the contents illustrated in FIGS. 2B to 2D. In more detail, the first ball-bottom metal material layer 340, the second patterned photoresist layer 420, and the second bump 330 are sequentially formed. Then, the second patterned photoresist layer 42 is removed and the patterned first ball-bottom metal material layer 340 is removed. Then, the first patterned photoresist layer 41 is removed. Referring to FIGS. 3E and 3F, a third patterned photoresist layer 430' is formed on the protective layer 230, and the second patterned patterned photoresist layer 430 covers the second bumps 330_ and the first bumps 310. Then, the second patterned bottom metal material layer 340 is patterned by using the third patterned photoresist layer 43 as a mask to form a second ball bottom metal layer 342. Referring to FIG. 3F, the third patterned photoresist is removed. Layer 34〇. Thus far, the manufacturing process of the multilayer bump structure 30A of the present embodiment is substantially completed. In addition, after the third patterned photoresist layer 430 is removed, a dicing process may also be performed on the substrate 210 to form a plurality of wafer structures (not shown). The detailed structure of the multilayer bump structure 300a will be described below. 12 200832645 oiN-y3u^ui>4 22160twf. doc/n, 0 3P H-% of the second embodiment of the multilayered bump structure. Referring to FIG. 3F, the multi-layer bump structure 3GGa is similar to the first embodiment, and the difference is that when the pad 22 〇 and the first bump 31 〇 are not (four) 'multi-layer bump structure 3 (10) a The second ball bottom metal layer 342 is disposed in the first opening 230a and located between the pads 22 and the first bumps 310 of the pad. The present invention has been disclosed in the above preferred embodiments, but it is intended to limit the invention, and any one of ordinary skill in the art can make a few changes from the spirit and scope of the present invention. The scope of protection is attached to the patent application of Fan Qizhen [Description of the drawings] Figure 1 is a cross-sectional view of a conventional gold bump. Figure 1 is a top plan view of a conventional gold bump. 2A to 2D are schematic views of a method of fabricating an embodiment of the present invention. Fig. 3A to Fig. 3F are schematic views showing a manufacturing method of the second embodiment of the present invention.夕层凸块 [Main component symbol description] 110 wafer 120: aluminum pad 130: protective layer 13 22160twf.doc/n 200832645 130a: opening 140: ball bottom metal layer 150: gold bump 150a: annular bump Portion 210: substrate 220: pad 230 · protective layer 230a: first opening 10 300: multi-layer bump structure 310: first bump 320: first ball-bottom metal material layer 322: first ball-bottom metal layer 330: Second bump 330a: top surface 340: second ball bottom metal material layer 342: second ball bottom metal layer • 410: first patterned photoresist layer 410 a: second opening 420: second patterned photoresist layer 420a: third opening 430: first patterned photoresist layer 14