414989 3749twt'.doc/006 A7 B7 五，、發明説明（/ ) 本發明是有關於一種製造護層的方法，且特別是有關 於一種對於使用一光罩以形成金屬銲墊之護層的製程中， 於護層蝕刻完後，降低金屬銲墊上之殘餘物的方法。 當整個積體電路的主要架構完成後，會在積體電路的 表面上形成一層護層，以用於保護位於其下方的積體電 路。而用於護層之理想的介電材料的性質須具備下列條 件：沈積均勻、抗裂能力佳、近乎無任何的孔洞（v〇id) 存在、能抵擋水氣及鹼金屬離子（Alkaline Ions)的穿透、 硬度（Hardness)佳’能承受機械性的損傷等。金屬銲墊的 材質通常爲鋁護鋁合金，鋁是現在VLSI最普遍採用的導電 材料’因爲鋁的導電性良好，價格便宜，易於沈積與蝕刻， 而且對矽的附著力亦不錯，因此常被使用來做爲晶片的銲 墊。 形成金屬銲墊之護層比較常見的材料有磷矽玻璃 (PSG)、氮化矽（SiN,)和聚乙醯氨(Polyimide)。其中磷 矽玻璃因爲含有具備吸氣（Gettering)能力的磷原子，因 此可以有效的減少水氣及鹼金屬離子的摻透，以延長積體 電路的壽命（Lifetime)。而氮化矽的密度極高，且硬度極 強，可以用來抵擋外界水氣及鹼金屬離子的穿透’並保護 元件免於遭受永久的機械性傷害。聚亞醯胺則有防水的效 果，可以使元件防水。 通常護層具有上述三層結構，磷矽玻璃層爲最下層’ 直接覆蓋在金屬銲墊上方，氮化矽層爲中間層’覆蓋於憐 矽玻璃層上方，而在氮化矽層上方’還有一聚亞醯胺層爲 3 ------^---：· —-裝------1T----- (却先閱讀背Is.之注意事項再填巧本1 ) 本紙張尺度適用屮囤國家榇準（CNS ) A4規格（2丨0X297公釐） 好洸部中"'^碑/只工消贽合作妇印y 414989 3749twt'.d〇c/006 B7 _ —·*_ I , 丨- --— I 一 五、發明説明（之） 最上層。 金屬銲墊之護層的製程通常可分爲使用一光罩和使用 二光罩兩種，使用一光罩的金屬銲墊之護層結構比使用二 光罩的金屬銲墊之護層結構少一道光罩，可降低循環時間 (Cycle Time) ’因此本發明係針對使用一光覃的金屬銲墊 之護層結構所面臨的問題做一改善。 第1A圖至第1B圖係繪示習知一種使用一光罩以形成 金屬銲墊之護層的製造流程剖面圖。 首先請參照第1A圖，金屬層12以下的MOS元件與半 導體基底10沒有完全繪出，其中金屬層12的材質比如是 鋁或鋁合金。金屬層12以下的積體電路均已完成’金屬層 12是金屬內連線中最上層的金屬層。完成金屬層12的定 義以形成金屬銲墊12後，接著在金屬銲墊12上形成共形 的（Conformal)磷矽玻璃層14，其方法比如是常壓化學氣 相沈積（APCVD)法或電漿增強化學氣相沈積（PECVD) 法，用以保護其下方的積體電路，避免與水氣和鹼金屬離 子接觸。 接著，在磷矽玻璃層Η上形成一層較厚的氮化矽層 16，其方法比如是APCVD或PECVD，以便於抵擋外來的 水氣、鹼金屬離子及機械性的刮傷（Scratch)。之後於氮 化矽層16上覆蓋一層聚亞醯胺層18，用來防止水氣的摻 入。 接著請參照第1B圖，在使用一個光罩以形成金屬銲楚 之護層的製程中，護層的定義方法如下所述。由於聚亞酿 4 >•紙張尺度通《屮囤國家標準（CNS ) A4规格（210X297公釐） ^ . I I I ! 訂 —線 {誚先閱讀背'&'之注意事項再填巧本頁) 414989 3749twf.doc/006 A7 B7 五、發明説明（多） 胺層18的材質有類似於光阻的功用，可對其直接進行微影 (Photolithography)，經微影定義接合銲塾（Bonding Pad) 後，形成聚亞醯胺層18a =以聚亞醯胺層18a爲蝕刻罩幕， 對其下方的氮化矽層16和磷矽玻璃層14進行蝕刻，使其 形成氮化矽層16a和磷矽玻璃層14a，以暴露出其下方的金 屬銲墊12。由於聚亞醯胺層18a會濟」险有機溶劑，因此於 蝕刻完後只能以水淸洗即直接出貨。 然而，由於在進行氮化矽層16和磷矽玻璃層14的蝕 刻製程中，使用含有氟的蝕刻劑，於蝕刻完成後，會有一 些氟化物在金屬銲墊表面形成殘餘物20，因爲只能以水進 行淸洗步驟，但是以水淸洗銲墊表面往往不能將殘餘物20 完全去除乾淨，使得金屬銲墊12表面還是會有殘餘物20 存在，久置後會發生金屬銲墊被氟腐蝕的現象’將嚴重影 響其外觀及後續之打線（Bonding)製程的良率。 因此本發明的主要目的，就是在提供一種護層製造及 其定義的方法，可以有效的去除金屬銲墊表面之殘餘物， 以避免金屬銲墊被腐蝕。 爲達成上述和其他目的，本發明提供一種護層製造及 其定義的方法，包括：提供已形成金屬銲墊之晶片，於金 屬銲墊上方依序形成磷矽玻璃層、氮化矽層、以及聚亞醯 胺護層，接著蝕刻聚亞醯胺護層、氮化矽層、以及磷矽玻 璃層’以暴露出金屬銲墊。金屬銲墊乏表面於蝕刻完後， 會存在有一些殘餘物，利用電漿灰化這些殘餘物後，再進 行水洗步驟，用以去除金屬銲墊表面之殘餘物。 本紙張尺度適州十國囤家樣準（CNS ) A4说格（2丨0X297公釐）414989 3749twt'.doc / 006 A7 B7 V. Description of the invention (/) The present invention relates to a method for manufacturing a protective layer, and in particular to a process for forming a protective layer using a photomask to form a metal pad. Method for reducing residues on metal pads after the protective layer is etched. When the main structure of the integrated circuit is completed, a protective layer is formed on the surface of the integrated circuit to protect the integrated circuit below it. The properties of the ideal dielectric material used for the protective layer must have the following conditions: uniform deposition, good crack resistance, almost no voids, and resistance to water vapor and alkali metal ions (Alkaline Ions) It has good penetration and hardness, and can withstand mechanical damage. The material of metal pads is usually aluminum-protected aluminum alloy. Aluminum is the most commonly used conductive material in VLSI now. Because aluminum has good conductivity, is cheap, easy to deposit and etch, and has good adhesion to silicon, it is often used Used as a pad for a wafer. The most common materials used to form the protective layer of metal pads are phosphosilicate glass (PSG), silicon nitride (SiN,), and polyimide. Among them, phosphosilicate glass contains phosphorus atoms with gettering ability, so it can effectively reduce the penetration of water vapor and alkali metal ions, and extend the life of the integrated circuit (Lifetime). Silicon nitride has a very high density and high hardness, which can be used to resist the penetration of external water vapor and alkali metal ions' and protect the components from permanent mechanical damage. Polyurethane has a waterproof effect, which can make the component waterproof. Usually the protective layer has the above-mentioned three-layer structure. The phosphorous-silica glass layer is the lowest layer, which directly covers the metal pads. The silicon nitride layer is the middle layer. There is a polyimide layer of 3 ------ ^ ---:-------------------- 1T ----- (However, please read the precautions of Is. Before filling in the book 1 ) This paper size is applicable to the National Standard (CNS) A4 size (2 丨 0X297 mm). The Ministry of Foreign Affairs " '碑石 / 工 工 消 贽 用 妇 印 414989 3749twt'.d〇c / 006 B7 _ — · * _ I, 丨---- I I. Five, the description of the invention (the top). The manufacturing process of the protective layer of metal pads can be divided into two types: one mask and two masks. The protective layer structure of metal pads using one mask is less than the protective layer structure of metal pads using two masks. A photomask can reduce the cycle time. Therefore, the present invention aims to improve the problems faced by the protective layer structure of a metal pad using a photocell. 1A to 1B are cross-sectional views showing a conventional manufacturing process using a photomask to form a protective layer of a metal pad. First, referring to FIG. 1A, the MOS device and the semiconductor substrate 10 below the metal layer 12 are not completely drawn. The material of the metal layer 12 is, for example, aluminum or aluminum alloy. The integrated circuits below the metal layer 12 have been completed. 'The metal layer 12 is the uppermost metal layer among the metal interconnects. After the definition of the metal layer 12 is completed to form the metal pads 12, a conformal phosphosilicate glass layer 14 is then formed on the metal pads 12 by a method such as atmospheric pressure chemical vapor deposition (APCVD) method or electrical The slurry enhanced chemical vapor deposition (PECVD) method is used to protect the integrated circuits below it from contact with water vapor and alkali metal ions. Next, a thicker silicon nitride layer 16 is formed on the phosphosilicate glass layer 其. The method is, for example, APCVD or PECVD, in order to resist external moisture, alkali metal ions, and mechanical scratches. Then, a silicon nitride layer 16 is covered with a polyimide layer 18 to prevent the incorporation of moisture. Next, please refer to FIG. 1B. In the process of using a photomask to form the protective layer of the metal welding layer, the method of defining the protective layer is as follows. As Juya 4 > • Paper sizes are in accordance with the "National Standard (CNS) A4 Specification (210X297 mm) ^. III! Order-Line {诮 Read the precautions of '&' before filling out this page ) 414989 3749twf.doc / 006 A7 B7 V. Description of the Invention (Poly) The material of the amine layer 18 has a function similar to that of photoresist, which can be directly lithographic (Photolithography), and the bonding pad is defined by the lithography (Bonding Pad) ), Forming a polyimide layer 18a = using the polyimide layer 18a as an etching mask, etching the silicon nitride layer 16 and the phosphosilicate glass layer 14 below it to form a silicon nitride layer 16a and A phosphosilicate glass layer 14a to expose the metal pads 12 below it. Since the polyurethane layer 18a can be a hazardous organic solvent, it can only be shipped directly after washing with water. However, since the etching process of the silicon nitride layer 16 and the phosphosilicate glass layer 14 is performed by using an etchant containing fluorine, after the etching is completed, some fluorides may form a residue 20 on the surface of the metal pad because only The cleaning step can be performed with water, but the surface of the pad is often not completely removed by washing the surface of the pad with water, so that the surface of the metal pad 12 will still have the residue 20. After a long time, the metal pad will be fluorinated. The phenomenon of corrosion will seriously affect its appearance and the yield of the subsequent bonding process. Therefore, the main object of the present invention is to provide a method for manufacturing a protective layer and a method for defining the same, which can effectively remove the residue on the surface of the metal pad to prevent the metal pad from being corroded. In order to achieve the above and other objectives, the present invention provides a method for manufacturing a protective layer and a definition thereof, including: providing a wafer having formed a metal pad, and sequentially forming a phosphosilicate glass layer, a silicon nitride layer on the metal pad, and The polyurethane protective layer, and then the polyurethane protective layer, the silicon nitride layer, and the phosphosilicate glass layer are etched to expose the metal pads. After the etched surface of the metal pads, there will be some residues. After the residues are ashed with a plasma, a water washing step is performed to remove the residues on the surface of the metal pads. The size of this paper is the same as that of the ten countries in the state (CNS) A4 (2 丨 0X297 mm)
I 意 4 Φ % 裝 本衣 % ____ 訂 線 好浸部中""·^^^工消贽合作妇印^ 414989 3749twi'.doc/006 A 7 B7 五、發明説明（各） 本發明係針對使用一光罩以形成金屬銲墊之護層的製 程中，於護層蝕刻完後，由於使用的蝕刻劑，比如含氟的 蝕刻劑，會於所暴露出之金屬銲墊表面存在蝕刻劑的殘餘 物，比如爲Alh以及A1(0F)X，而此殘餘物會於金屬銲墊 表面久置後，使金屬銲墊產生腐蝕的情形，除了將嚴重影 響外觀外，還會影響後續之打線製程的良率。 爲讓本發明之上述和其他目的、特徵、和優點能更明 顯易懂，下文特舉一較佳實施例，並配合所附圖式，作詳 細說明如下： 圖式之簡單說明： 第1A圖至第1B圖係繪示習知一種使用一光罩來形成 金屬銲墊之護層結構的流程剖面圖； 第2A圖至第2C圖係繪示根據本發明較佳實施例之一 種於使用一光罩來形成金屬銲墊之護層結構的流程剖面 圖； 第3A圖係顯示習知一種使用一光罩來形成金屬銲墊 之護層的製程中，於護層蝕刻後，不經任何後續步驟所形 成之金屬銲墊表面之Auger光譜； 第3B圖係顯示習知一種使用一光罩來形成金屬銲墊 之護層結構，於護層蝕刻後，再進行水洗步驟所形成之金 屬銲墊表面之Auger光譜； 第3C圖係顯示本發明使用一光罩來形成及定義的金 屬銲墊之護層結構，於護層蝕刻後，先以電漿灰化金屬靜 墊表面之殘留物*再進行水洗步驟所形成之金屬銲墊表面 6 --11---^---—善-- ("先队讀背面七注意事項再^寫本1) XT _ *-° 線 本纸張尺度適/1]中因國家標準（CNS ) A4规格{ 2!0Χ297公釐） ^τ"部中呔^:^^0^乂消贽合作妇印果 414989 3749twt'.doc/006 A 7 B7 五、發明説明（f ) 之Auger光譜。 第4A圖係顯示習知一種使用一光罩來形成金屬銲墊 之護層的製程中，於護層蝕刻後，不經任何後續步驟所形 成之金屬銲墊表面之表面原子含量圖； 第4B圖係顯示習知一種使用一光罩來形成金屬銲墊 之護層結構，於護層蝕刻後，再進行水洗步驟所形成之金 屬銲墊表面之表面原子含量圖； 第4C圖係顯示本發明使用一光罩來形成及定義的金 屬銲墊之護層結構，於護層蝕刻後，先以電漿灰化金屬銲 墊表面之殘留物，再進行水洗步驟所形成之金屬銲墊表面 之表面原子含量圖。 其中，各圖標號與構件名稱之關係如下： 10、100 半導體基底 12 ' 112 金屬銲墊 14、14a、114、114a 憐砂玻璃層 16 ' 16a ' 116' 116a 氮化砂層 18 ' 18a ' 118 ' 118a 聚亞醯胺層 20、120 :殘餘物 122 氧化層 1、 F1 :氟的訊號 2、 A12 :鋁的訊號 實施例 第2A圖至第2C圖所示，爲根據本發明一較佳實施例 之一種於使用一光罩以形成金屬銲墊之護層的製程中，降 7 ---^-------If------IT-----.^ (誚先閱讀背面之注意事項再填巧本頁) 本紙張尺度通州中囤國家標準（CNS ) A4说格{ 210X297公釐) 414989 3749twf.doc/006 A7 B7 一 五、發明説明（6 ) 低其金屬銲墊上殘餘物之方法的流程剖面圖° 首先請參照第2A圖，金屬層112以下的MOS元件與 半導體基底100沒有完全繪出，其中金屬層112的材質比 如是鋁或鋁合金。包含金屬層112以下的積體電路均已完 成，金屬層112是金屬內連線中最上層的金屬層。完成金 屬層112的定義以形成金屬銲墊U2後’接著在金屬銲墊 112上形成共形的磷矽玻璃層114,其方法比如是常壓化學 氣相沈積法或電漿增強化學氣相沈積法’用以保護其下方 的積體電路，避免與水氣和鹼金屬離子接觸。 接著，在磷矽玻璃層114上形成一層較厚的氮化矽層 116，其方法比如是APCVD或PECVD，以便於抵擋外來的 水氣、鹼金屬離子及機械性的刮傷。之後於氮化矽層116 上覆蓋一層聚亞醯胺層Π8，用來防止水氣的滲入。 接著請參照第2B圖，對使用一個光罩來形成並定義的 金屬銲墊之護層結構而言，護層的蝕刻方法如下所述。由 於聚亞醯胺層118的材質有類似於光阻的功用，可對其直 接進行微影，經微影定義後，形成聚亞醯胺層118a。以聚 亞醯胺層118a爲蝕刻罩幕，對其下方的氮化矽層116和磷 矽玻璃層114進行蝕刻，使其形成氮化矽層i 16a和磷矽玻 璃層114a，以暴露出其下方的金屬銲墊112。由於在進行 氮化矽層116和磷矽玻璃層114的蝕刻製程中，比如使用 含有氟的蝕刻劑，因此會有含氟蝕刻劑在金屬銲墊112的 表面形成殘餘物120。 由於聚亞醯胺層118a材質會溶於有機溶劑，因此於蝕 ---^---Γ丨丨I—束------訂-----線 {誚先M-讀背面之注意事項再蛾荇本页) 本紙張尺度通州中家插準（CNS ) A4規格（2丨OX297公龙~ — 414989 3749twf.d〇c/006 _________ ____B7________ 五、發明説明（"） 刻完後無法使用有機溶劑做淸洗，而應以水爲淸洗液進行 淸洗步驟。但是由於殘餘在金屬銲墊表面的氟化物以AIFx 以及A1(0F)X兩種形式存在，其中AlFx不容易溶於水，因 此水洗步驟不能將殘留之AlFx淸除乾淨。本發明爲了淸洗 金屬銲墊112上殘餘的AlFx，以避免元件久置後會發生鋁 腐蝕的現象，因此，於蝕刻完後以氧電漿灰化法將殘留在 金屬銲墊表面的AlFx變成容易被水溶解的Al(OF)x，之後 再進行水洗的步驟，以降低金屬銲墊Π2表面的氟含量。 因此本發明可以保有元件的外觀，且可提高打線製程的良 率。 請參照第3A圖，其係顯示習知一種使用一光罩以形成 金屬銲墊之護層於蝕刻製程後，金屬銲墊表面之Auger光 譜。Auger光譜圖中的波峰（Peak) 1代表氟的訊號，波峰 2代表鋁的訊號，其中鋁的訊號係來自於金屬銲墊112。 請參照第3B圖，其係顯示習知一種使用一光罩以形成 金屬銲墊之護層於蝕刻製程後，再經過水洗步驟後之金屬 銲墊表面之Auger光譜。與第3A圖比較之後可知，在波峰 2的強度相當時，3B圖中的波峰1比3A圖中的波峰1在強 度上小很多。由此可知，於蝕刻護層後，進行水洗步驟確 實有助於去除金屬銲墊表面之殘留物，但是以水淸洗只能 去除殘餘在金屬銲墊表面之A1F*，但是A1(0F)X仍然殘餘在 金屬銲墊表面，因此在3B圖的Auger光譜中波峰1的訊號 仍然相當強。 接著請參照第3C圖，其係顯示習知一種使用一光罩的 9 本紙張Ζΐϋ十®囡家#準（) A4規格（2】〇X297公釐） ---------1¾衣------iT-----k - . (誚1M-讀背面之注意事項再填寫本f ) 414989 3749twf.doc/006 A7 _B7___ 五、發明説明（） 金屬銲墊之護層於蝕刻步驟後，先以氧電漿灰化金屬銲墊 表面之殘留物，再經過水洗步驟後之金屬銲墊表面之Auger 光譜。與第3A圖及第3B圖做比較，可以發現在波峰1的 強度相當時，第3C圖中的波峰2強度明顯地變小。由此可 知，以氧電漿灰化金屬銲墊表面殘留物後再進行水洗的步 驟，確實可以有效的移除殘留物，因此可以有效避免金屬 銲墊112發生腐蝕。 請參照第4A圖至第4C圖，其分別繪示第3A圖至第 3B圖所指之金屬銲墊表面之表面原子含量圖。比對4A、 4B、4C三個圖可得知經過電漿灰化製程以及水洗步驟的金 屬銲墊表面所含的氟最少，只經過水洗步驟的金屬銲墊表 面所含的氟次之，而不經任何表面淸理步驟的金屬銲墊表 面則具有最多的氟。由此可證明先以電漿灰化殘餘物後再 以水淸洗金屬銲墊表面確實有效的消除了金屬銲墊表面的 氟殘餘物。 接著請參照第2C圖，當銲墊表面經氧電漿灰化及水洗 步驟後，會於金屬銲墊112的表面形成一層薄薄的氧化層 122,氧化層122由於厚度甚薄，因此不會對銲墊產生影響。 另外，氧化層122可以保護所暴露出之金屬銲墊112，防止 金屬銲墊112發生腐蝕的現象。 本發明的特徵如下所述：對於使用一光罩來形成及定· 義金屬銲墊之護層的製程中’本發明於護層蝕刻完後，利 用氧電漿將殘留在金屬銲墊表面上的AIR、變成容易被水溶 解的Al(OF)x，再以大量的水對晶片做淸洗，將Al(OF)x溶 ]〇 本紙张尺度通州十闽國家椋準{ CMS ) A4規格（2〗〇X297公釐） ' ---^---^----- —X於------1T-----0 » < * (諳先"讀背1&-之注意事項再硪艿本頁) 414989 3749twt'.d〇c/006 __ _____ B7 五、發明说明（？） 解後沖走，以此將蝕刻完所暴露出之金屬銲墊表面的氟殘 餘物淸理乾淨，進而避免晶片會於久置後產生腐蝕的情 形，因而增加打線製程的良率。 雖然本發明已以一較佳實施例揭露如上，然其並非用 以限定本發明，任何熟習此技藝者，在不脫離本發明之精 神和範圍內，當可作各種之更動與潤飾，因此本發明之保 護範圍當視後附之申請專利範圍所界定者爲準。 --—---^---;<·1.裝------訂-----〆線 ("先"讀背16·之注意事項再"寫本瓦) ^淥部中失^4'-^'1只-7-消於合作^印？?': 本紙張尺度適用中國阁家標準（CNS } A4規格（2i〇X297公釐）I meaning 4 Φ% 装 本 衣% ____ Thread in the immersion department " " · ^^^ 工 消 贽 贽 用 妇 印 ^ 414989 3749twi'.doc / 006 A 7 B7 V. Description of the invention (each) The invention It is directed to the process of using a photomask to form a protective layer of a metal pad. After the protective layer is etched, the used etchant, such as a fluorine-containing etchant, will etch on the surface of the exposed metal pad. Residues of the agent, such as Alh and A1 (0F) X, and this residue will cause corrosion of the metal pad after being left on the surface of the metal pad for a long time. In addition to seriously affecting the appearance, it will also affect the subsequent Yield of wire bonding process. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is described below in detail with the accompanying drawings as follows: Brief description of the drawings: FIG. 1A FIG. 1 to FIG. 1B are cross-sectional views of a conventional method for forming a protective layer structure of a metal pad by using a photomask; FIG. 2A to FIG. 2C are drawings showing a method of using a mask according to a preferred embodiment of the present invention. Figure 3A shows a conventional process for forming a protective layer of a metal pad by using a photomask. After the protective layer is etched, it is not subjected to any subsequent processes. Auger spectrum of the surface of the metal pad formed in the step; FIG. 3B shows a conventional protective layer structure using a photomask to form the metal pad. After the protective layer is etched, the metal pad formed by the water washing step is performed. The Auger spectrum of the surface; Figure 3C shows the protective layer structure of the metal pad formed and defined by the present invention using a photomask. After the protective layer is etched, the residue on the surface of the metal static pad is ashed by plasma. Perform the water washing step Surface of the metal pad 6 --11 --- ^ ----- good-- (" read the seven notes on the back before writing ^ 1) XT _ *-° The size of the paper is suitable for / 1] Medium Due to the national standard (CNS) A4 specification {2! 0 × 297 mm) ^ τ " Ministry of Foreign Affairs ^: ^^ 0 ^ 乂 Elimination of cooperation cooperation women printed fruit 414989 3749twt'.doc / 006 A 7 B7 V. Description of the invention (f ) Of Auger spectrum. FIG. 4A shows a conventional atomic content map of the surface of a metal pad formed in a conventional process using a photomask to form a protective layer of a metal pad, after the protective layer is etched, without any subsequent steps; FIG. 4B The figure is a conventional atomic content map of a metal pad formed by using a photomask to form a protective layer structure of a metal pad. After the protective layer is etched, a water washing step is performed; FIG. 4C shows the present invention. A photomask is used to form and define the protective layer structure of the metal pad. After the protective layer is etched, the residue on the surface of the metal pad is ashed by plasma, and then the surface of the surface of the metal pad formed by the water washing step is performed. Atomic content chart. Among them, the relationship between each icon number and component name is as follows: 10, 100 semiconductor substrate 12 '112 metal pads 14, 14a, 114, 114a sand glass layer 16' 16a '116' 116a nitrided sand layer 18 '18a' 118 ' 118a Polyurethane layer 20, 120: Residue 122 Oxidation layer 1, F1: Signal of fluorine 2, A12: Signal of aluminum Examples As shown in Figures 2A to 2C, they are a preferred embodiment according to the present invention. One is in the process of using a photomask to form a protective layer of metal pads, which reduces 7 --- ^ ------- If ------ IT -----. ^ (诮 先Read the notes on the back and fill in this page again.) This paper size is Tongzhou National Standard (CNS) A4 standard (210X297 mm) 414989 3749twf.doc / 006 A7 B7. 15. Description of the invention (6) Low metal welding Process flow sectional view of the method for padding the residue ° First, please refer to FIG. 2A. The MOS device and the semiconductor substrate 100 below the metal layer 112 are not completely drawn. The material of the metal layer 112 is, for example, aluminum or aluminum alloy. The integrated circuits including the metal layer 112 and below have been completed. The metal layer 112 is the uppermost metal layer of the metal interconnects. After the definition of the metal layer 112 is completed to form the metal pad U2, a conformal phosphosilicate glass layer 114 is then formed on the metal pad 112. The method is, for example, atmospheric pressure chemical vapor deposition or plasma enhanced chemical vapor deposition. The method is used to protect the integrated circuit below it from contact with water vapor and alkali metal ions. Next, a thicker silicon nitride layer 116 is formed on the phosphosilicate glass layer 114. The method is, for example, APCVD or PECVD, in order to resist external moisture, alkali metal ions, and mechanical scratches. Thereafter, a layer of polyimide layer Π8 is covered on the silicon nitride layer 116 to prevent the infiltration of moisture. Next, referring to FIG. 2B, for a protective layer structure of a metal pad formed and defined by using a photomask, an etching method of the protective layer is as follows. Since the material of the polyimide layer 118 has a function similar to that of photoresist, it can be directly lithographed. After being defined by the lithography, the polyimide layer 118a is formed. Using the polyimide layer 118a as an etching mask, the silicon nitride layer 116 and the phosphosilicate glass layer 114 underneath are etched to form a silicon nitride layer i 16a and a phosphosilicate glass layer 114a to expose the silicon nitride layer 116a and the phosphosilicate glass layer 114a. Below the metal pads 112. During the etching process of the silicon nitride layer 116 and the phosphosilicate glass layer 114, for example, a fluorine-containing etchant is used, a fluorine-containing etchant may form a residue 120 on the surface of the metal pad 112. Because the material of the polyimide layer 118a is soluble in organic solvents, it will be etched. --- ^ --- Γ 丨 丨 I-beam ------ order ----- line {诮 先 M-Read the back Note on this page again) This paper size Tongzhou Zhongjia Interpretation Standard (CNS) A4 specification (2 丨 OX297 Gonglong ~ — 414989 3749twf.d〇c / 006 _________ ____B7________ 5. The description of the invention is finished After that, it is not possible to use organic solvents for cleaning. Instead, use water as a cleaning solution to perform the cleaning step. However, since the fluoride remaining on the surface of the metal pads exists in the form of AIFx and A1 (0F) X, AlFx is not easy. It is soluble in water, so the residual AlFx cannot be cleaned out in the water washing step. The purpose of the present invention is to clean the residual AlFx on the metal pad 112 to avoid the phenomenon of aluminum corrosion after the component is left for a long time. The oxygen plasma ashing method changes the AlFx remaining on the surface of the metal pad to Al (OF) x which is easily dissolved by water, and then performs a water washing step to reduce the fluorine content on the surface of the metal pad Π2. Therefore, the present invention can keep The appearance of the component can improve the yield of the wire bonding process. Please refer to FIG. 3A, It shows the conventional use of a photomask to form a protective layer of a metal pad after the etching process. The Auger spectrum on the surface of the metal pad. Peak 1 in the Auger spectrum represents the signal of fluorine, and peak 2 represents the signal of aluminum. The signal, of which the aluminum signal is from the metal pad 112. Please refer to FIG. 3B, which shows a conventional method of using a photomask to form a protective layer of the metal pad after the etching process, and then the metal after the water washing step. Auger spectrum of the pad surface. Comparing with Fig. 3A, it can be seen that when the intensity of peak 2 is equivalent, peak 1 in Fig. 3B is much smaller than peak 1 in Fig. 3A. Therefore, it can be seen that it is used in the etching protection layer. After that, the water washing step does help to remove the residue on the surface of the metal pad. However, washing with water can only remove the A1F * remaining on the surface of the metal pad, but A1 (0F) X still remains on the surface of the metal pad. Therefore, the signal of peak 1 in the Auger spectrum of Fig. 3B is still quite strong. Next, please refer to Fig. 3C, which shows a conventional 9-sheet paper using a photomask. Zΐϋ 十 ® 囡 家 # 准 () A4 size (2 】 〇X297 mm) ------ --- 1¾ clothing ------ iT ----- k-. (诮 1M-Read the notes on the back and fill in this f) 414989 3749twf.doc / 006 A7 _B7___ V. Description of the invention () Metal welding After the protective layer of the pad is etched, the residue on the surface of the metal pad is ashed by an oxygen plasma, and then the Auger spectrum of the surface of the metal pad after the water washing step is compared with FIG. 3A and FIG. 3B. It was found that when the intensities of the peaks 1 are equal, the intensities of the peaks 2 in Fig. 3C are significantly reduced. It can be seen that the step of ashing the residue on the surface of the metal pad with oxygen plasma and then washing it with water can indeed effectively remove the residue, and thus can effectively prevent the corrosion of the metal pad 112. Please refer to FIGS. 4A to 4C, which respectively show the surface atomic content maps of the surfaces of the metal pads referred to in FIGS. 3A to 3B. Comparing the 3A, 4B, and 4C charts, it can be seen that the surface of the metal pad after the plasma ashing process and the water washing step contains the least fluorine, and the surface of the metal pad after the water washing step has the second lowest fluorine, and The surface of the metal pad without any surface treatment step has the most fluorine. It can be proved that the residue on the surface of the metal pad is effectively eliminated by ashing the residue with plasma and then washing the surface of the metal pad with water. Next, please refer to FIG. 2C. After the pad surface is subjected to oxygen plasma ashing and water washing steps, a thin oxide layer 122 will be formed on the surface of the metal pad 112. The oxide layer 122 will not be thin because it is very thin. Has an impact on the pads. In addition, the oxide layer 122 can protect the exposed metal pads 112 and prevent the metal pads 112 from being corroded. The features of the present invention are as follows: For the process of forming and defining a protective layer of a metal pad using a photomask, the present invention uses an oxygen plasma to leave residues on the surface of the metal pad after the protective layer is etched. AIR, becomes Al (OF) x that is easily dissolved by water, and then rinses the wafer with a large amount of water to dissolve Al (OF) x] 〇 This paper is standard Tongzhou Shimin National Standard {CMS) A4 specification ( 2〗 〇X297mm) '--- ^ --- ^ ----- —Xyu ------ 1T ----- 0 »< * (谙 先 " Read Back 1 & -Notes on this page) 414989 3749twt'.d〇c / 006 __ _____ B7 V. Description of the invention (?) After the solution is removed, the fluorine residue on the surface of the exposed metal pad is etched. The physical structure is clean, so as to avoid the situation that the wafer will be corroded after being placed for a long time, so the yield of the wire bonding process is increased. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and decorations without departing from the spirit and scope of the present invention. The scope of protection of the invention shall be determined by the scope of the attached patent application. ------ ^ ---; < · 1. Install ------ order ----- 〆 line (" Read " Notes after reading 16. · Then, " Writing a tile) ^ Lost in the Ministry ^ 4 '-^' 1 only -7- due to cooperation ^ India? ? ': This paper size applies the Chinese cabinet standard (CNS} A4 size (2i × 297mm)