529113 3411twf.doc/006 A7 B7 經濟部中央標準局貝工消費合作社印繁 五、發明説明（/ ) 本發明是有關於一種降低金屬銲墊（Bonding Pad) 上之氟（F)含量的方法，且特別是有關於一種對於使用 一光罩的聚亞醯胺護層結構而言，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（Void) 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。 比較常見的材料有氮化矽（SiNx)和磷矽玻璃（PSG)。 其中氮化矽的密度極高，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。而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)。最後會在氮 化矽層上方，再沈積一層聚亞醯胺（Polyimide)亦做爲 護層，可以使元件防水。 聚亞醯胺護層的製程通常可分爲使用一光罩和使用 二光罩兩種，使用一光罩的聚亞醯胺護層結構比使用二光 罩的聚亞醯胺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罩的聚亞醯 胺護層結構所面臨的問題做一改善。 另外，金屬鋁是現在VLSI最普遍採用的導電材料， 3 (請先閱讀背面之注意事項再填寫本頁) 衣. 、11 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 529113 3411twf.doc/006 A' B7 ____ 五、發明説明（二） 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，因此被使用來做爲元件的導線。 第1A圖至第1B圖所示，係繪示習知使用一光罩的聚 亞醯胺護層結構之一種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。包含金屬層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 和驗金屬離子接觸。 接著，在磷矽玻璃層14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，用來防止水氣的滲 入。 經濟部中央標準局貝工消費合作社印製 (請先閲讀背面之注意事項再填寫本頁) 接著請參照第1B圖，對使用一個光罩的聚亞醯胺層 護層結構而言，護層的餓刻方法如下所述。由於聚亞醯胺 層18的材質有類似於光阻的功用，可對其直接進行微影 (Photolithography)，經微影定義接合靜墊（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 經濟部中央標準局貝工消費合作社印繁 529113 341 ltwf.doc/006 A 7 __B7______ 五、發明説明（多） 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材質的關係， 其會溶於有機溶劑，因此於鈾刻完後無法做適當的淸洗即 直接出貨。 然而’由於在進行氮化矽層16和磷矽玻璃層丨4的蝕 刻製程中，使用含有氟的蝕刻劑，然蝕刻完成後，因無法 做適當的淸洗步驟，使金屬銲墊12表面會有氟存在，久 置後會發生鋁腐蝕的現象，將嚴重影響其外觀及後續之打 線（Bonding)製程的良率。 於完後銲墊的建立後，進行構裝（packaging)，由 於此部份非關本發明，在此不多做說明。 因此本發明的主要目的，就是在提供一種降低金屬銲 墊上之殘餘物的方法，以避免金屬銲墊的腐蝕。 爲達成本發明之上述和其他目的，〜種降低金屬銲墊 上之殘餘物的方法，包括：提供已形成金屬銲墊之晶片， 於金屬銲墊上方形成第一護層和聚亞醯胺護層，接著定義 聚亞醯胺護層和第一護層，以暴露出金屬銲墊，金屬銲墊 之表面於蝕刻完後，會存在有一殘餘物。利用去離子水淸 '冼晶片’用以去除金屬銲墊表面之殘餘物。 本發明係針對使用一光罩的聚亞醯胺護層結構，於護 層餓刻完後，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 氟’而此殘餘物會於晶片久置後，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 尺度&中ϋϋ?Τ^Τ^ΓΓ2Κ)χ 297:)--- (請先閱讀背面之注意事項再填寫本頁)529113 3411twf.doc / 006 A7 B7 Yin Fan, Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs, Yin Fan 5. Description of the invention (/) The present invention relates to a method for reducing the fluorine (F) content on metal bonding pads. In particular, it relates to a method for reducing a residue on a metal pad after a protective layer is etched for a polyurethane protective layer structure using a photomask. 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 for the protective layer must have the following conditions: uniform deposition, good crack resistance, almost no Voids, and resistance to the penetration of water and alkali metal ions (Alkaline Ions). It has good transparency and hardness, and can withstand mechanical damage. The more common materials are silicon nitride (SiNx) and phosphosilicate glass (PSG). Among them, silicon nitride has extremely 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. Phosphosilicate glass contains phosphorus atoms with gettering ability, so it can effectively reduce the penetration of water vapor and alkali metal ions, so as to extend the life of the integrated circuit (Lifetime). Finally, a layer of polyimide is also deposited on the silicon nitride layer as a protective layer, which can make the component waterproof. The manufacturing process of the polyimide protective layer can generally be divided into two types: using a photomask and using a two-photomask. The polyimide protective layer structure using a single photomask is less than the polyimide protective layer structure using a two-photomask. A photomask can reduce the cycle time. Therefore, the present invention aims to improve the problems faced by the polyurethane protective layer structure using a photomask. In addition, metal aluminum is the most commonly used conductive material in VLSI today. 3 (Please read the precautions on the back before filling this page). 11 Paper size is applicable to Chinese National Standard (CNS) A4 specification (210X297 mm) 529113 3411twf.doc / 006 A 'B7 ____ 5. Description of the Invention (2) Because aluminum has good conductivity, is cheap, easy to deposit and etch, and has good adhesion to silicon, it is used as a component wire. 1A to 1B are cross-sectional views showing a manufacturing process of a protective layer of a conventional polyurethane protective layer structure using a photomask. 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 including the metal layer 12 and below have been completed, and the metal layer 12 is the uppermost metal layer in the metal interconnect. After the definition of the metal layer _ 12 is completed to form the metal pad 12, a conformal phosphosilicate glass layer 14 is then formed on the metal pad 12. The method is, for example, atmospheric pressure chemical vapor deposition (APCVD) or The plasma enhanced chemical vapor deposition (PECVD) method is used to protect the integrated circuit below it from contact with moisture and metal ions. Next, a thicker silicon nitride layer 16 is formed on the phosphosilicate glass layer 14. The method is, for example, APCVD or PECVD, so as to resist external moisture, alkali metal ions, and mechanical scratches. Thereafter, a silicon nitride layer 16 is covered with a polyimide layer 18 to prevent water vapor from penetrating. Printed by the Shell Standard Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs (please read the precautions on the back before filling out this page). Then refer to Figure 1B. For the protective structure of the polyurethane layer using a photomask, the protective layer The method of starving is described below. Because the material of the polyimide layer 18 has a function similar to that of photoresist, it can be directly subjected to photolithography, and the polyimide layer 18a is formed after bonding with a bonding pad by the lithography definition. The polyimide layer 18a is used as an etching mask, and the silicon nitride layer 16 and the phosphosilicate glass layer 14 underneath are etched. The Central Standards Bureau of the Ministry of Economic Affairs, Shellfish Consumer Cooperative, India 529113 341 ltwf.doc / 006 A 7 __B7______ 5. Description of the invention (multiple) etching, so that it forms a silicon nitride layer 16a and a phosphosilicate glass layer 14a, so as to expose the metal pads 12 below it. Due to the material of the polyimide layer 18a, it will dissolve in organic solvents, so it cannot be shipped directly after the uranium is etched. However, 'Since the etching process of the silicon nitride layer 16 and the phosphosilicate glass layer 4 is performed, an etchant containing fluorine is used. However, after the etching is completed, an appropriate cleaning step cannot be performed, so that the surface of the metal pad 12 may be damaged. The presence of fluorine will cause aluminum corrosion after a long period of time, which will seriously affect its appearance and the yield of the subsequent bonding process. After the pads are established, packaging is performed. Since this part is not related to the present invention, it will not be described here. Therefore, the main object of the present invention is to provide a method for reducing the residue on the metal pad to avoid the corrosion of the metal pad. In order to achieve the above and other objectives of the present invention, a method for reducing residue on a metal pad includes providing a wafer having a metal pad formed thereon, and forming a first protective layer and a polyurethane protective layer over the metal pad. Next, define the polyurethane protective layer and the first protective layer to expose the metal pads. After the surface of the metal pads is etched, there will be a residue. Deionized water is used to remove the residue on the surface of the metal pad. The invention is directed to a polyurethane protective layer structure using a photomask. After the protective layer is engraved, the used etchant, such as a fluorine-containing etchant, will etch on the surface of the exposed metal pad. Residues, such as fluorine, and this residue will cause metal pads to corrode after the wafer is left for a long time. In addition to seriously affecting the appearance, it will also affect the subsequent wire bonding process scale & Τ ^ ΓΓ2Κ) χ 297:) --- (Please read the notes on the back before filling in this page)
、1T 529113 經濟部中央標準局貝工消費合作社印策 3411twf.doc/006 A7 __B7 五、發明説明（¥ ) 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圖係繪示習知使用一光罩的聚亞醯胺 護層結構之一種護層蝕刻的流程剖面圖； 第2A圖至第2C圖係繪示根據本發明較佳實施例之一 種於使用一光罩的聚亞醯胺護層之結構，降低其金屬銲墊 上之殘餘物之方法的流程剖面圖；以及 第3A圖至第3D圖係顯示一種利用本發明之降低金屬 銲墊上之氟含量的方法，於護層蝕刻完後，將晶片用去離 子分別浸泡0、10、20和30分鐘後之Augur光譜。 其中，各圖標號與構件名稱之關係如下： 10、1〇〇 半導體基底 12、112 金屬銲墊 14、14a、114、114a 磷矽玻璃層 16、16a、116、116a 氮化砂層 18、18a、118、118a 聚亞醯胺層 120氧化層 1氟的訊號 2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 ____ 6 本紙張尺度適用中國國家系^( CNS ) A4規格（210X2^^ ~ (請先閱讀背面之注意事項再填寫本頁) 衣· ，11 #1 529113 經濟部中央標準局貝工消費合作社印$ί 3411twf.doc/006 A 7 _________B7 五、發明説明（< ) 之一種於使用一光罩的聚亞醯胺護層的結構，降低其金屬 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112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118，用來防止水氣的滲入。 接著請參照第2B圖，對使用一個光罩的聚亞醯胺層 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116a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，因此在金屬銲墊112的表面會有殘餘的含氟 蝕刻劑。 7 —本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閱讀背面之注意事項再填寫本頁) 衣· 、-5口 f 529113 3411twf.doc/006 A 7 _B7____ 五、發明説明（（） 由於聚亞醯胺層118a材質的關係，其會溶於有機溶 劑，因此於蝕刻完後無法使用有機溶劑做淸洗。本發明爲 了淸洗金屬銲墊112上殘餘的氟，以避免元件久置後會發 生鋁腐蝕的現象，因此，於蝕刻完後以去離子水 (Deionized Water; DI water)進行淸洗。因此本發明 的特徵在於將金屬銲墊112蝕刻後之晶片，浸泡於去離子 水中，以降低金屬銲墊112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。 經濟部中央標準局負工消費合作社印1i (請先閱讀背面之注意事項再填寫本頁) 第3A圖至第3D圖係顯示一種利用本發明之降低金屬 銲墊上之氟含量的方法，於護層蝕刻完後，將晶片用去離 子分別浸泡0、10、20和30分鐘後之Augur光譜。Augur 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。以波峰1 的訊號強度對波峰2的訊號強度做比較，可以發現當晶片 浸泡於去離子水中的時間增長時，波峰1的訊號強度對波 峰2的訊號強度比會降低，比如浸泡1〇分鐘後其訊號強 度比約爲0.95，浸泡20分鐘後其訊號強度比約爲0.55， 浸泡30分鐘後其訊號強度比約爲0.44。經由實驗證實， 隨浸泡時間的增長，本發明確實可以降低金屬銲墊112之 氟含量，因此可以有效避免金屬歸墊112發生腐蝕。 接著請參照第2C圖，當晶片經去離子淸洗後，會於 金屬靜墊112的表面形成一層薄薄的氧化層120，此層氧 化層120由於甚薄，因此不會對銲墊產生影響。另外，此 層氧化層120可以保護所暴露出之金屬銲墊112，防止金 8 本紙張尺度適用中國國家標準（CNS ) Μ規格（210X297公" 529113, 1T 529113 Yince, Consumers Cooperative of Central Bureau of Standards, Ministry of Economic Affairs 3411twf.doc / 006 A7 __B7 V. Yield of invention description (¥). 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 showing a process of etching a protective layer of a conventional polyurethane protective layer structure using a photomask. FIGS. 2A to 2C are drawings according to a preferred embodiment of the present invention. A process cross-sectional view of a method for reducing the residue on a metal pad of a polyurethane protective layer structure using a photomask; and FIG. 3A to FIG. 3D show a method for lowering a metal pad by using the present invention. In the method of fluorine content, after the protective layer is etched, the wafers are immersed with deionization for 0, 10, 20, and 30 minutes, respectively, and the Augur spectrum. Among them, the relationship between each icon number and the component name is as follows: 10, 100 semiconductor substrates 12, 112 metal pads 14, 14a, 114, 114a phosphosilicate glass layers 16, 16a, 116, 116a nitrided sand layers 18, 18a, 118, 118a Polyimide layer 120 Oxidation layer 1 Fluorine signal 2 Aluminium signal embodiment As shown in Figures 2A to 2C, it is a preferred embodiment according to the present invention ____ 6 This paper size is applicable to the Chinese National ^ (CNS) A4 specifications (210X2 ^^ ~ (Please read the precautions on the back before filling in this page) Clothing · ， 11 # 1 529113 Printed by the Shellfish Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs $ ί 3411twf.doc / 006 A 7 _________B7 V. Description of the invention (<) A cross-sectional view of a method for reducing the residue on the metal pads of a structure using a polyurethane protective layer of a photomask. First, please refer to FIG. 2A, the metal layer 112 The following MOS device and semiconductor substrate 100 are not completely drawn. The material of the metal layer 112 is, for example, aluminum or aluminum alloy. Integrated circuits including the metal layer 112 and below have been completed, and the metal layer 112 is the uppermost layer of the metal interconnect. Metal layer. Finished metal layer 11 The definition of 2 is to form a metal pad 112, and then form a conformal phosphosilicate glass layer 114 on the metal pad 112. The method is, for example, atmospheric pressure chemical vapor deposition or plasma enhanced chemical vapor deposition. In order to protect the integrated circuit below it from contact with water gas and alkali metal ions. Next, a thicker silicon nitride layer 116 is formed on the phosphosilicate glass layer 114, such as APCVD or PECVD, in order to resist External moisture, alkali metal ions, and mechanical scratches. Then, a silicon nitride layer 116 is covered with a polyurethane layer 118 to prevent the penetration of moisture. Then refer to Figure 2B. In terms of the protective structure of the polyimide layer of the photomask, the method of etching the protective layer is described below. Since the material of the polyimide layer 118 has a function similar to that of photoresist, it can be directly lithographically processed. After the definition, a 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 below are etched to form a silicon nitride layer 116a. And phosphosilicate glass layer 114a to expose the gold beneath Pad 112. Since the etching process of the silicon nitride layer 116 and the phosphosilicate glass layer 114, for example, uses an etchant containing fluorine, there will be residual fluorine-containing etchant on the surface of the metal pad 112. 7 — This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) (Please read the precautions on the back before filling this page) Clothing, -5 mouth f 529113 3411twf.doc / 006 A 7 _B7____ V. Description of the invention (() Due to the material of the polyimide layer 118a, it will dissolve in organic solvents, so organic solvents cannot be used for cleaning after etching. In the present invention, the residual fluorine on the metal pad 112 is cleaned to avoid the phenomenon of aluminum corrosion after the component is left for a long time. Therefore, the etching is performed with deionized water (DI water) after the etching. Therefore, the present invention is characterized in that the wafer after the metal pad 112 is etched is immersed in deionized water to reduce the fluorine content on the surface of the metal pad 112. Therefore, the present invention can maintain the appearance of the component and improve the yield of the wire bonding process. Printed by the Central Standards Bureau of the Ministry of Economic Affairs and Consumer Cooperatives 1i (please read the precautions on the back before filling out this page) Figures 3A to 3D show a method for reducing the fluorine content on metal pads using the present invention. After the layer was etched, the Augur spectra of the wafers were immersed with deionization for 0, 10, 20, and 30 minutes, respectively. Peak 1 in the Augur spectrogram represents the signal of fluorine, and peak 2 represents the signal of aluminum. The aluminum signal comes from the metal pad 112. By comparing the signal intensity of peak 1 to the signal intensity of peak 2, we can find that when the time of immersion of the wafer in the deionized water increases, the ratio of the signal intensity of peak 1 to the signal intensity of peak 2 decreases, such as after 10 minutes The signal intensity ratio is about 0.95. After 20 minutes of immersion, the signal intensity ratio is about 0.55. After 30 minutes of immersion, the signal intensity ratio is about 0.44. It has been confirmed through experiments that, as the immersion time increases, the present invention can indeed reduce the fluorine content of the metal pad 112, and thus can effectively prevent the metal pad 112 from corroding. Please refer to FIG. 2C. After the wafer is cleaned by deionization, a thin oxide layer 120 is formed on the surface of the metal static pad 112. The oxide layer 120 is very thin, so it will not affect the pad. . In addition, this layer of oxide 120 can protect the exposed metal pads 112 and prevent gold. The paper size applies the Chinese National Standard (CNS) M specification (210X297 male " 529113
五、發明説明（7 ) 屬鍵塾112發牛腐鈾。 於完後靜墊的建立後，進行構裝，由於此部份非關本 發明，在此不多做說明。 本發明的特徵如下所述：對於1光罩聚亞醯胺護層的 結構，本鋼賴層關雜’ #胃曰% 片做淸洗，以除去誠完祕挪之金腦酿面的_ 餘物，進而避免晶片能久㈣產生腐關·，因而增 加打線製程的良率。 雖然本發明已以-較隹實施例揭露如上，然其並非用 以限定本觀，任何熟習技藝者，在不讎本發明之精 神和關，當可作各種之Ϊ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。 ------------^11 衣— (請先閱讀背面之注意事項再填寫本頁) 、11 f. 經濟部中央標準局貝工消費合作社印聚 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐〉V. Description of the invention (7) It is a bond of 112 rounds of bovine rotting uranium. After the completion of the establishment of the static pad, the construction is performed. Since this part is not related to the present invention, it will not be described here. The features of the present invention are as follows: For the structure of the 1-layer polyimide protective layer, the steel layer of the Benxi Iron and Steel Co., Ltd. '# Weiss% tablets are rinsed to remove the golden brain noodles that have been removed sincerely. Remainder, thereby preventing the wafer from being damaged for a long time, thereby increasing the yield of the wire bonding process. Although the present invention has been disclosed in the above-mentioned embodiments, it is not intended to limit the concept. Any person skilled in the art can make various movements and retouches without jeopardizing the spirit and key points of the present invention. Therefore, the present invention The scope of protection shall be determined by the scope of the attached patent application. ------------ ^ 11 衣 — (Please read the precautions on the back before filling this page), 11 f. Printed by the Central Standards Bureau of the Ministry of Economic Affairs, Shellfish Consumer Cooperatives, the paper size is applicable to China Standard (CNS) A4 specification (210X297 mm>