1337twf. doc/006 A7 B7 五、發明説明（/ ) 本發明是有關於一種半導體元件多重內連線 (Multilevel Interconnects)的製作方法，且特別是有關於 一種改善金屬層回蝕刻的製程方法。 在許多高積極度的半導體電路中，係以插塞作爲單 一積體電路元件的多重內連線或作爲元件之間的多重內連 線。傳統的製程係於所形成的第一層配線層上沈積一層內 金屬介電層之後’再穿透內金屬介電層，裸露出部份的第 一層配線層，以形成一介層窗。然後，於介層窗以及內金 屬介電層上沈積金屬，再經由回蝕刻，以形成多重內連線 的插塞。 鎢，具有高熔點，而熱膨脹係數又與矽相當，再加上 以化學氣相沈積法所沈積的鎢的內應力並不高，且具備極 佳的階梯覆蓋能力。因此，以化學氣相沈積法所沈積的鎢， 已儼然成爲目前廣爲業界所使用的一種插塞材料。現今， 鎢插塞的製程主要是採用一種所謂的「有回蝕」（With Etch Back)的鎢插塞製程，以製作半導體元件的多重內連線。 通常，有回蝕的鎢插塞製程包括二步驟，其一爲主蝕 刻，另一爲過度蝕刻（Over Etch)。主蝕刻是在化學氣相 沈積法沈積鎢之後，進行乾式蝕刻，以大部份地去除內金 屬介電層表面多餘的金屬。而過度蝕刻則是在進行主蝕刻 之後，再進行一蝕刻，以去除主蝕刻後在內金屬層表面所 殘餘之金屬，確保量產化的半導體製程之蝕刻製程，可以 徹底地將被蝕刻的金屬層加以淸除。 以下將以有回蝕的鎢插塞與內連線的製作方法，並配 3 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公ί!~~ " (請先閲讀背面之注意事項再填寫本頁) 訂 錄 1337twf.doc/006 A7 B7 埵齊郎中失揉隼苟貝工消費合作狂印敦 五、發明説明（1) 合圖式以說明有回蝕之蝕刻系統。 第1A圖至第1E圖爲傳統有回蝕之鎢插塞的作法。首 先，請參照第1A圖所示，在已完成MOS主體及第一層金 屬層製作的基底100上，形成一介電層102，以隔離兩金 屬層。接著’請參照第1B圖，以一光阻罩幕覆蓋於介電 層1〇2之上，進行微影製程，以定義用以連接不同金屬層 間的連線通道，形成一接觸窗或介層窗104，暴露出基底 1〇〇表面。 其後’請參照第1C圖，先於介電層上以及介層窗所 暴露出的基底100表面形成一黏著金屬層1〇6，例如，鈦 金屬層。接著’再以物理氣相沈積法，於黏著金屬層106 上形成一厚度約爲800A至1200A的阻障層108，例如， 氮化鈦層。然後，於阻障層1〇8上沈積一耐熱性佳且導電 性良好的金屬層110，例如，鎢金屬層，使其覆蓋阻障層 108表面，並將介層窗1〇4塡滿。 接著，請參照第1D圖，以氮化鈦阻障層爲蝕刻終點， 回蝕鎢金屬層，形成一鎢插塞110a。通常，蝕刻製程包括 二步驟’其一爲主蝕刻，另一爲過度蝕刻。此蝕刻製程請 參照第2圖，首先，在金屬層形成之後，以含氟的氣體作 爲蝕刻之氣體源，例如，四氟化碳與氧氣（CF4/02)、氟 化氮與氧（NF3/02)或氟化硫與氧（SF6/02)的混合氣體， 進行—主蝕刻200，以氮化鈦阻障層做爲一蝕刻終點，回 蝕鎮金屬層，去除大部份沈積於內金屬介電層之上的鎢金 屬層’形成一鎢金屬插塞。其後，進行一過度蝕刻202， (請先閲讀背面之注意事項再填寫本頁) -s 1337twf,doc/006 A7 五、發明説明（3 ) 以去除主蝕刻後在介電層ι〇2表面所殘餘之金屬，確保量 產化的半導體製程之蝕刻製程，可以徹底將被蝕刻的金屬 層加以淸除。 請參照第1E圖’由於乾式蝕刻製程中所通入的氣體 源，可同時進行蝕刻反應與聚合反應。其中，蝕刻反應係 氣體源形成之電漿粒子與金屬所進行之化學反應，此化學 反應生成揮發性的氣體，使多餘之金屬可予以去除。而聚 合反應則是氣體源形成的電漿粒子彼此之間所進行之反 應，此聚合反應所形成之副產物1丨4，例如，聚合物，將 沈積於元件的表面之上。在蝕刻反應與聚合反應相互競爭 的結果’雖然仍以蝕刻反應爲主，而去除了大部份沈積於 內金屬介電層之上的金屬，但是，卻也因爲聚合反應而生 成了少許副產物114’包覆蝕刻後所殘餘之金屬112。所 以，在進行主蝕刻之後所進行之過度蝕刻，雖可將部份主 蝕刻所殘餘之金屬予以去除，然而，由於蝕刻的競爭反應 所生成之聚合物Π4,包覆蝕刻後所殘餘之金屬Π2,使 殘餘金屬112獲得聚合物114的保護，導致殘餘金屬112 的去除更爲不易，而造成必須耗費很長的時間以進行過度 蝕刻202。而長時間的過度蝕刻202製程不但缺乏效率， 更常造成氮化鈦阻障層1〇8與金屬黏著層106的破壞，以 及介層窗內1〇4的金屬鎢亦遭受到過度蝕刻的現象，造成 金屬插塞的損失（Plug Loss)，而導致製程的良率下降。 此外，在金屬回蝕的過程中，在一些具有凹凸不平幾 何構形的表面結構中’例如，第1F _所示，類似於鳥嘴 5 本紙張尺度適用中國國家標準（CNS > A4現格（21〇><297公釐） — I I I I I 訂 I I I I I 線 ― (請先閲讀背面之注意事項再填寫本頁) 1337twf.doc/006 A7 1337twf.doc/006 A7 經濟部中央樣隼局貝工消費合作社印製 B7 五、發明説明（f) 狀氧化層10〗與基底100平面所形成之接觸角，亦常造成 淸除的困難，致使金屬或副產物105的殘餘。 因此本發明的主要目的就是在提供一種改善金屬回触 刻的製程方法，使蝕刻的金屬目的物可予以去除，亦使蝕 刻製程所產生的副產物可以徹底地淸除。以避免爲了去除 副產物所包覆的殘餘金屬，致使過度蝕刻製程的時間延 長，而導致插塞的損失及其所衍生的其他問題。 根據本發明的目的，提出一種改善金屬回蝕刻的製程 方法，此方法的步驟包括：提供一積體電路結構，此結構 至少具有一介層窗穿過一已形成金氧半導體的基底上的.介 電層，且一鎢金屬已覆蓋介層窗上之阻障層與介層窗。首 先，進行一主要蝕刻步驟，以蝕刻部份的金屬目的物。接 著，進行第一過蝕刻步驟，以蝕刻主要蝕刻步驟殘餘之金 屬。其後，進行一氣體淸除步驟，以淸除主要蝕刻步驟所 生成之副產物。然後，進行第二過蝕刻步驟，以蝕刻殘餘 之金屬。之後，重複進行氣體淸除步驟與第二過蝕刻步驟， 直至金屬目的物與副產物完全淸除爲止。 其中，主要蝕刻步驟係將基底置於反應器中，通人含 氟之氣體源，例如四氟化碳與氧氣、氟化氮與氧或氟化硫 與氧的混合氣體以進行之。而氣體淸除步驟則可以兩種方 式進行。其一是持續通入氣體流的方法，是在進行主蝕刻 後，關閉蝕刻電漿之電源，在持續通入原氣體源的情況下， 藉由氣體進行淸除的一種方法。其二是藉由壓力的變化與 淨氣（Purge )的方法以施行淸除的步驟，此方法係在進 6 本紙張尺度適用中國國家標準（CNS ) A4規格（210X29*7公釐） (#_先閲讀背面之注意事項再填寫本頁)1337twf. Doc / 006 A7 B7 V. Description of the Invention (/) The present invention relates to a method for manufacturing multilevel interconnects of semiconductor devices, and in particular, to a method for improving the etch-back process of a metal layer. In many highly active semiconductor circuits, plugs are used as multiple interconnects of a single integrated circuit component or as multiple interconnects between components. The traditional process is to deposit an inner metal dielectric layer on the first wiring layer formed, and then penetrate the inner metal dielectric layer to expose a part of the first wiring layer to form a dielectric window. Then, metal is deposited on the interlayer window and the inner metal dielectric layer, and then etched back to form plugs with multiple interconnects. Tungsten has a high melting point, and its thermal expansion coefficient is comparable to that of silicon. In addition, the internal stress of tungsten deposited by chemical vapor deposition is not high, and it has excellent step coverage. Therefore, tungsten deposited by the chemical vapor deposition method has become a plug material widely used in the industry. At present, the manufacturing process of tungsten plugs mainly uses a so-called "With Etch Back" tungsten plug process to make multiple interconnects of semiconductor devices. Generally, an etched tungsten plug process includes two steps, one is a main etch, and the other is an over etch. The main etch is a dry etch after chemical vapor deposition of tungsten to remove most of the excess metal on the surface of the inner metal dielectric layer. Over-etching is to perform an etching after the main etching to remove the metal remaining on the surface of the inner metal layer after the main etching to ensure the mass production of the semiconductor process. The etching process can completely etch the metal Layers are eradicated. The following will use the method of making etched tungsten plugs and interconnects, and 3 paper sizes are applicable to the Chinese National Standard (CNS) A4 specification (210X297). Please read the precautions on the back first (Fill in this page again) Order 1337twf.doc / 006 A7 B7 埵 齐 郎中 失 隼 Gou Beigong Consumption Cooperation Kazakhstan Five. Description of the Invention (1) Combine drawings to illustrate the etching system with etch back. Figure 1A Figure 1E to 1E are the traditional tungsten plugs with etch-back. First, referring to Figure 1A, a dielectric layer 102 is formed on the substrate 100 on which the MOS body and the first metal layer have been fabricated. In order to isolate the two metal layers. Then, please refer to FIG. 1B, cover the dielectric layer 102 with a photoresist mask, and perform a lithography process to define the connection channels used to connect different metal layers to form A contact window or interlayer window 104 exposes the surface of the substrate 100. Thereafter, referring to FIG. 1C, an adhesive metal layer 1 is formed on the dielectric layer and the surface of the substrate 100 exposed by the interlayer window. 6. For example, a titanium metal layer. Then 'physical vapor deposition is used to adhere to gold A barrier layer 108, such as a titanium nitride layer, is formed on the layer 106 to a thickness of about 800 A to 1200 A. Then, a metal layer 110 having good heat resistance and good conductivity is deposited on the barrier layer 108, for example, The tungsten metal layer covers the surface of the barrier layer 108 and fills the interlayer window 104. Next, referring to FIG. 1D, the tungsten nitride layer is etched back with the titanium nitride barrier layer as an end point to form A tungsten plug 110a. Generally, the etching process includes two steps, one is mainly etching, and the other is over-etching. Please refer to FIG. 2 for this etching process. First, after the metal layer is formed, a fluorine-containing gas is used as the etching. Gas source, for example, a mixture of carbon tetrafluoride and oxygen (CF4 / 02), nitrogen fluoride and oxygen (NF3 / 02) or sulfur fluoride and oxygen (SF6 / 02), the main etching 200, to The titanium nitride barrier layer is used as an etching end point, and the town metal layer is etched back to remove most of the tungsten metal layer deposited on the inner metal dielectric layer to form a tungsten metal plug. Thereafter, an over-etching is performed. 202, (Please read the notes on the back before filling this page) -s 1337twf, doc / 006 A7 Explanation (3) In order to remove the metal remaining on the surface of the dielectric layer ι2 after the main etching to ensure the mass production of the semiconductor manufacturing process, the etched metal layer can be completely removed. Please refer to Section 1E Figure 'Because of the gas source passed in the dry etching process, the etching reaction and the polymerization reaction can be performed simultaneously. Among them, the etching reaction is a chemical reaction between plasma particles formed by the gas source and the metal, and this chemical reaction generates a volatile Gas, so that excess metal can be removed. Polymerization is a reaction between plasma particles formed by a gas source, and by-products formed by this polymerization reaction, such as polymers, will be deposited on On the surface of the component. As a result of the competition between the etching reaction and the polymerization reaction, although the etching reaction is still the main part, and most of the metal deposited on the inner metal dielectric layer is removed, a small amount of by-products are also generated due to the polymerization reaction. 114 'covers the metal 112 remaining after the etching. Therefore, the excessive etching performed after the main etching can remove some of the remaining metal from the main etching, however, the polymer Π4 generated due to the competitive reaction of the etching, and the remaining metal Π2 after the etching is covered As a result, the residual metal 112 is protected by the polymer 114, which makes the removal of the residual metal 112 more difficult, which results in that it must take a long time to perform the overetch 202. The long-term over-etching 202 process not only lacks efficiency, but also often causes damage to the titanium nitride barrier layer 108 and the metal adhesion layer 106, and the metal tungsten in the interlayer window 104 also suffers from over-etching. , Resulting in the loss of metal plugs (Plug Loss), which leads to a decline in the yield of the process. In addition, in the process of metal etchback, in some surface structures with uneven geometries' for example, as shown in 1F _, similar to the bird's beak 5 This paper size applies the Chinese national standard (CNS > A4 is present) (21〇 > < 297mm) — Order IIIII line IIIII-(Please read the precautions on the back before filling this page) 1337twf.doc / 006 A7 1337twf.doc / 006 A7 Shellfisher, Central Samples Bureau, Ministry of Economy Printed by consumer cooperative B7 V. Description of the invention (f) The contact angle formed by the oxide layer 10 and the plane of the substrate 100 often causes difficulty in eradication, resulting in the residue of metal or by-product 105. Therefore, the main purpose of the present invention It is to provide a process method for improving metal back-contact engraving, so that the etched metal objects can be removed, and the by-products generated by the etching process can be completely eliminated. This is to avoid removing the residual metal coated by the by-products. According to the purpose of the present invention, a method for improving the process of metal etch-back is provided. The steps of this method include: providing an integrated circuit structure, the structure having at least a dielectric window through a dielectric layer on a substrate where a metal-oxide semiconductor has been formed, and a tungsten metal covering the resistance on the dielectric window. Barrier layer and interlayer window. First, a main etching step is performed to etch a part of the metal object. Then, a first over-etching step is performed to etch the remaining metal in the main etching step. Thereafter, a gas elimination is performed. Step to remove the by-products generated in the main etching step. Then, a second over-etching step is performed to etch the remaining metal. After that, the gas removal step and the second over-etching step are repeated until the metal object and the by- The product is completely eliminated. Among them, the main etching step is to place the substrate in a reactor and pass in a fluorine-containing gas source, such as a mixed gas of carbon tetrafluoride and oxygen, nitrogen fluoride and oxygen, or sulfur fluoride and oxygen. The gas scavenging step can be performed in two ways. One method is to continuously pass in the gas flow. After the main etching, the power of the etching plasma is turned off. In the case of continuing to pass in the original gas source, a method of purging by gas. The second is to perform the purging step by changing the pressure and the method of purging gas (Purge). Paper size applies Chinese National Standard (CNS) A4 specification (210X29 * 7mm) (#_Read the precautions on the back before filling this page)
1337twf.doc/006 A7 B7 锤*·郎中夹雉隼苟貝工消費合作社印裝 五、發明説明（<) 行主蝕刻後，關閉蝕刻電漿之電源，並藉由栗浦（PumP) 抽真空，將反應器的壓力降低之後’再通入氣體流’使壓 力增加至5T〇rr之後，再將壓力回復至執行蝕刻製程之條 件以進行副產物之淸除。 爲讓本發明之上述目的 '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1E圖繪示習知多重內連線之製造流程剖 面圖； 第1F圖繪示鳥嘴氧化層與基底所形成之接觸角的殘 餘物； 第2圖繪示習知之金屬插塞之製造流程圖； 第3A圖至第3D圖繪示本發明之實施例，金屬插塞之 製造流程剖面圖；以及 第4圖繪示依照本發明之改善蝕刻製程之方法流程 圖。 圖式標記說明： 100，300 基底 ιοί 鳥嘴狀氧化層 102，302 介電層 104, 304 介層窗或接觸窗 105 殘餘物 106，306 黏著層 、 7 本紙張尺度適用中國國家標準（CNS > A4规格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁)1337twf.doc / 006 A7 B7 Hammer * · Printed by Lang Zhongjiao Gou Bei Gong Consumer Cooperative Co., Ltd. 5. Description of the invention (&) After the main etching, turn off the power of the etching plasma, and draw it by PumP (PumP) Vacuum, after reducing the pressure of the reactor, 're-into the gas flow' to increase the pressure to 5 Torr, and then return the pressure to the conditions of the etching process to remove the by-products. In order to make the aforementioned features and advantages of the present invention more comprehensible, a preferred embodiment is given below in conjunction with the accompanying drawings for detailed description as follows: Brief description of the drawings: FIG. 1A to FIG. Figure 1E shows a cross-sectional view of the manufacturing process of a conventional multiple interconnect; Figure 1F shows the residue of the contact angle formed by the bird's beak oxide layer and the substrate; Figure 2 shows the manufacturing process of a conventional metal plug FIGS. 3A to 3D are cross-sectional views of a manufacturing process of a metal plug according to an embodiment of the present invention; and FIG. 4 is a flowchart of a method for improving an etching process according to the present invention. Description of graphical symbols: 100, 300 substrates, beak-shaped oxide layers 102, 302 dielectric layers 104, 304 interlayer windows or contact windows 105 residues 106, 306 adhesive layers, 7 paper standards are applicable to Chinese national standards (CNS > A4 size (210X297mm) (Please read the precautions on the back before filling in this page)
*1T 錄_ 337twf.doc/006 A7 B7 經濟部中央樣隼局員工消費合作社印製 五、發明説明（ό) 108，308 障層 110，310 金屬 110a，310a 插塞 112 殘餘金屬 114 聚合物 200，400 主蝕刻步驟 202，402，406 過度蝕刻步驟 404 淸除步驟 408 判斷是否達成製程之需求 實施例 以下將以有回蝕的鎢插塞與內連線的製作方法，並配 合圖式以說明本發明之蝕刻製程的方法。 首先，請參照第3A圖所示，在已完成MOS主體及第 一層金屬層製作的基底300上，形成一介電層302 ’以隔 離兩金屬層，較佳的介電層係包含一層或兩層旋塗式玻璃 的三明治結構介電層，此結構可避免純粹以化學氣相沈積 法製作介電層時，所面臨的孔洞問題。三明治結構介電層 係以電漿加強型化學氣相沈積法（PECVD)，通入四乙氧 基矽甲烷（TEOS)作爲前趨氣體，進行氧化層的沈積’ 以形成第一介電層。其後，於第一氧化層之上形成一層旋 塗式玻璃層，經烘烤、固化後，再於旋塗式玻璃層上形成 第二介電層的沈積，即完成具有三明治結構之介電層3〇2。 接著，請參照第3B圖，以一光阻罩幕覆蓋於介電層302 之上，進行微影、蝕刻製程，以定義用以連接不同金屬層 8 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閲讀背面之注$項再填寫本頁) -* 1337twf. doc/006 A7 B7 五、發明説明（Q ) 間的連線通道，形成一接觸窗或介層窗304，暴露出基底 300表面。 其後，請參照第3C圖，爲了增加後續形成之鎢插塞 與其他材質之間的附著能力，在沈積鎢金屬之前，先沈積 一層氮化鈦或鎢化鈦，除了可以提昇附著力之外，還可以 藉著鎢蝕刻與氮化鈦或鎢化鈦蝕刻的電漿光譜的差異性， 做爲鎢金屬蝕刻終止的指標。事實上，氮化鈦在金屬化製 程上的應用，是和金屬鈦一起搭配，而以Ti/TiN的形式 組成。所以在金屬插塞形成之前，可先於介電層302上以 及介層窗304所暴露出的基底300表面形成一黏著金屬層 306，例如’鈦金屬層。接著，再以物理氣相沈積法，於 黏著金屬層306上形成一厚度約爲800A至1200A的阻障 層308，例如，氮化鈦層。其後，於阻障層308上沈積一 耐熱性佳且導電性良好的金屬層310，例如，鎢金屬層， 使其覆蓋阻障層308表面，並將介層窗304塡滿。通常， 爲了增加化學氣相沈積法所沈積的鎢對其他材質的附著能 力，較佳的CVD金屬鎢的沈積製程在lTorr〜lOOTorr的壓 力，300〜550°C的溫度下以兩個步驟進行。首先，先沈積 一層厚度較薄的長晶層（Nucleation Layer)金屬鎢。其後， 再將所需之鎢金屬的厚度約爲5000〜10000A沈積至長晶層 然後，請參照第3D圖，在鎢金屬沈積後，以氮化鈦 阻障層爲蝕刻終點，進行一蝕刻製程以形成一鎢插塞 310a。此蝕刻製程請參照第4圖，首先，在鎢金屬層310 9 本紙張尺度適用中國國家標準（CNS > Μ规格（21〇X297^釐) (請先閲讀背面之注意事項再填寫本頁)* 1T Record _ 337twf.doc / 006 A7 B7 Printed by the Consumer Cooperatives of the Central Sample Bureau of the Ministry of Economic Affairs. 5. Description of invention 108, 308 Barrier layer 110, 310 Metal 110a, 310a Plug 112 Residual metal 114 Polymer 200 , 400 Main etching step 202, 402, 406 Over-etching step 404 Deletion step 408 Determining whether the process requirements are met The method of the etching process of the present invention. First, referring to FIG. 3A, a dielectric layer 302 'is formed on the substrate 300 on which the MOS body and the first metal layer have been fabricated to isolate the two metal layers. A preferred dielectric layer includes one or Sandwich structure dielectric layer of two-layer spin-on glass, this structure can avoid the problem of holes when the dielectric layer is made purely by chemical vapor deposition. The sandwich structure dielectric layer is formed by a plasma enhanced chemical vapor deposition (PECVD) method, in which tetraethoxysilylmethane (TEOS) is introduced as a precursor gas, and an oxide layer is deposited to form a first dielectric layer. Thereafter, a spin-on glass layer is formed on the first oxide layer. After baking and curing, a second dielectric layer is formed on the spin-on glass layer to complete the dielectric with a sandwich structure. Layer 30. Next, please refer to FIG. 3B, cover the dielectric layer 302 with a photoresist mask, and perform a lithography and etching process to define different metal layers. 8 The paper size applies the Chinese National Standard (CNS) A4 Specifications (210X297 mm) (Please read the note on the back before filling in this page)-* 1337twf. Doc / 006 A7 B7 5. The connection channel between the description of the invention (Q) forms a contact window or interlayer window 304. The surface of the substrate 300 is exposed. After that, please refer to Figure 3C. In order to increase the adhesion between the tungsten plug formed later and other materials, before depositing tungsten metal, deposit a layer of titanium nitride or titanium tungsten, in addition to improving the adhesion. It can also be used as an indicator of the termination of tungsten metal etching based on the difference between the plasma spectra of tungsten etching and titanium nitride or titanium tungsten oxide etching. In fact, the application of titanium nitride in the metallization process is combined with titanium metal, and is composed of Ti / TiN. Therefore, before the metal plug is formed, an adhesive metal layer 306, such as a 'titanium metal layer, may be formed on the dielectric layer 302 and the surface of the substrate 300 exposed by the dielectric window 304. Then, a physical vapor deposition method is used to form a barrier layer 308, such as a titanium nitride layer, on the adhesive metal layer 306 to a thickness of about 800A to 1200A. Thereafter, a metal layer 310, such as a tungsten metal layer, having good heat resistance and good conductivity is deposited on the barrier layer 308 so as to cover the surface of the barrier layer 308 and fill the via window 304. Generally, in order to increase the adhesion of tungsten deposited by chemical vapor deposition to other materials, the preferred CVD metal tungsten deposition process is performed in two steps at a pressure of 1 Torr to 100 Torr at a temperature of 300 to 550 ° C. First, a thin layer of tungsten (Nucleation Layer) is deposited. After that, the required tungsten metal is deposited to a crystalline layer with a thickness of about 5000 to 10000 A. Then, referring to FIG. 3D, after the tungsten metal is deposited, an etching is performed with the titanium nitride barrier layer as an etching end point. Processed to form a tungsten plug 310a. Please refer to Figure 4 for this etching process. First, the paper size of tungsten metal layer 310 9 applies the Chinese national standard (CNS > M specification (21〇X297 ^ cent)) (Please read the precautions on the back before filling this page)
、1T 1337twf·doc/006 A7 B7 五、發明説明（另） 形成之後，以含氟的氣體作爲蝕刻之氣體源’例如，四氟 化碳與氧氣、氟化氮與氧或氟化硫與氧的混合氣體，以氮 化鈦阻障層306做爲一蝕刻終點，進行一主蝕刻4〇〇，回 蝕鎢金屬層310 ’以去除大部份沈積於介電層302之上的 鎢金屬層310，形成一鎢插塞31〇a。接著，進行第一過蝕 刻步驟402 ’以蝕刻主要蝕刻步驟300所殘餘之鎢金屬。 其後，進行第一氣體淸除步驟404，以淸除蝕刻步驟所生 成之聚合物，暴露出包覆於蝕刻步驟殘餘之鎢金屬。然後， 進行第二過度蝕刻步驟406，以蝕刻殘餘之鎢金屬。之後， 判斷是否達成製程之需求408。若「是」，則結束此蝕刻 製程。若「否」，則重複進行氣體淸除步驟404與第二過 蝕刻步驟406,直至殘餘的金屬鎢與聚合物完全淸除爲止。 經發明者實驗發現，通常只需進行二次的過度蝕刻步驟， 與一次的氣體淸除步驟，即可達到製程之需求。第一次的 過度蝕刻時間約爲1秒至15秒之間，較佳的時間約爲1 秒至5秒之間。 本發明在蝕刻製程之後所執行的氣體淸除步驟可以兩 種方法進行。第一種是持續通入氣體源的方法，此方法是 在進行第一過度蝕刻402後，關閉蝕刻電漿之電源，在持 續通入原氣體源的情況下，由於不會進行進將蝕刻與沈 積，因此利用氣體淸除蝕刻步驟所生成之副產物，例如是 含硫之聚合物，能暴露出包覆於主要蝕刻步驟所殘餘之金 屬。第二種方法則是藉由壓力的變化與淨氣（Purge)的 方法以施行淸除的步驟，此方法係在進行第一過度蝕刻 本紙張尺度適用中圉國家揉準（CNS ) Α4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁) 訂 線 绖濟郎中夬蜾隼苟貝Μ消費合作杜印製 1337twf.doc/〇〇6 A7 B7 五、發明说明（Θ ) 後，關閉蝕刻電漿之電源’並藉由泵浦（pump)抽真空， 將反應器的壓力降低至真空’例如約爲1〇-7Torr之後，再 通入氣體流’使壓力增加例如是40mTorr至5_T〇rr之間， 利用壓力之改變’將包覆在表面因主蝕刻產生之副產物去 除。之後，再使反應器的壓力回復至執行蝕刻製程之條件， 以進行回蝕刻步驟將金屬之殘餘物去除。 在形成所需之鎢插塞之後’後續之製程將是進行下一 層金屬層的沈積、微影與蝕刻製程’以製作積體電路所需 之第二層內連線，其步驟與習知相同，在此不多贅述。 雖然，本發明已以一金屬插塞的形成揭露如上，然經 由發明者實驗發現此氣體淸除步驟除了可以去除一平面上 的聚合物或雜質’亦可以去除一些以習知方法無法去除的 特殊幾何構型其表面上之聚合物或雜質’包括，第1F圖 所示之類似於鳥嘴氧化層與基底平面所形成之接觸角的殘 餘物。 因此，本發明的特徵之一係在傳統的主要蝕刻步驟與 短時間的過度蝕刻步驟之後，增加一道氣體清除的步驟。 由於，此氣體淸除步驟可以去除蝕刻製程的競爭反應所生 成之副產物，使包覆於聚合物之內的殘餘金屬裸露出來， 因此，不需長時間的過度蝕刻即可以使主蝕刻所殘餘之金 屬予以去除。此外，經發明者實驗發現，通常只需進行二 次的過度蝕刻製程與一次的氣體淸除步驟，即可達到製程 之需求，由於此二次過度蝕刻的時間遠小於傳統只進行一 次過度蝕刻的時間，而且氣體淸除步驟所通入的氣體源的 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁)1T 1337twf · doc / 006 A7 B7 V. Description of the invention (other) After the formation, a fluorine-containing gas is used as an etching gas source. For example, carbon tetrafluoride and oxygen, nitrogen fluoride and oxygen, or sulfur fluoride and oxygen Mixed gas, using the titanium nitride barrier layer 306 as an etching end point, performing a main etching 400, and etching back the tungsten metal layer 310 'to remove most of the tungsten metal layer deposited on the dielectric layer 302 310, a tungsten plug 31a is formed. Next, a first over-etching step 402 'is performed to etch the tungsten metal remaining in the main etching step 300. Thereafter, a first gas depletion step 404 is performed to remove the polymer generated in the etching step, and the tungsten metal remaining in the etching step is exposed. Then, a second over-etching step 406 is performed to etch the remaining tungsten metal. After that, it is determined whether the process requirement 408 is reached. If "Yes", the etching process is ended. If no, repeat the gas elimination step 404 and the second over-etching step 406 until the remaining metal tungsten and polymer are completely eliminated. Experiments by the inventors have found that usually only two over-etching steps and one gas scavenging step are needed to meet the process requirements. The first overetching time is between about 1 second and 15 seconds, and the preferred time is between about 1 second and 5 seconds. The gas scavenging step performed after the etching process of the present invention can be performed by two methods. The first method is to continuously pass on the gas source. This method is to turn off the power of the etching plasma after the first over-etching 402. Under the condition that the original gas source is continuously passed on, since the etching and Deposition, so that by-products generated during the etching step, such as a sulfur-containing polymer, can be removed by gas to expose the metal remaining in the main etching step. The second method is to perform the eradication step by the change in pressure and the Purge method. This method is to perform the first over-etching on this paper. The national standard (CNS) A4 specification ( 210X297 mm) (Please read the notes on the back before filling out this page) Threaded line: Jilang Zhongguo Goubei Consumer Cooperation Du printed 1337twf.doc / 〇〇6 A7 B7 5. After the description of the invention (Θ) , Turn off the power of the etching plasma 'and pump down the vacuum to reduce the pressure of the reactor to a vacuum' for example, after about 10-7 Torr, then pass in a gas flow 'to increase the pressure, for example, 40 mTorr to Between 5_Torr, the change in pressure is used to remove the by-products produced on the surface due to the main etching. After that, the pressure of the reactor is returned to the conditions for performing the etching process, so as to perform an etch-back step to remove metal residues. After the required tungsten plug is formed, 'the subsequent process will be the next metal layer deposition, lithography and etching process' to make the second layer of interconnects required for the integrated circuit, the steps are the same as conventional I wo n’t go into details here. Although the present invention has been disclosed as above with the formation of a metal plug, the inventors found that this gas elimination step can remove polymers or impurities on a flat surface. It can also remove some special features that cannot be removed by conventional methods. The geometric configuration of the polymer or impurities on its surface includes, as shown in Figure 1F, a residue similar to the contact angle formed by the bird's beak oxide layer and the plane of the substrate. Therefore, one of the features of the present invention is the addition of a gas removal step after the conventional main etching step and the short-time over-etching step. Since this gas elimination step can remove the by-products generated by the competitive reaction of the etching process, and expose the residual metal coated in the polymer to bareness, therefore, it is possible to make the remaining of the main etching unnecessary without long-term over-etching. Remove the metal. In addition, the inventor's experiments have found that it usually only needs to perform a second over-etching process and a single gas elimination step to meet the process requirements. Because the time of this second over-etching is far less than the traditional one-time over-etching Time, and the paper size of the gas source passed in the gas elimination step applies the Chinese National Standard (CNS) A4 specification (210X297 mm) (Please read the precautions on the back before filling this page)
、1T 線 1337twf.doc/006 A7 1337twf.doc/006 A7 經濟部中央樣隼局員工消費合作杜印製 B7 五、發明説明（/0 ) 方向與基底表面平行，即與插塞的構形相互垂直，因此， 不會造成插塞的損失。是故，本發明不但可縮短製程的時 間，減少製程的成本，更因此而避免時間過長的過度蝕刻 製程所造成金屬插塞損失的現象，故而，可使製程的良率 大大地提昇。 本發明的特徵之二係氣體淸除步驟可以採用兩種方式 進行。第一種方式是持續通入原氣體源的方法，係關閉餓 刻電漿之電源，在持續通入原氣體源的情況下進行。第二 種方式則是籍由壓力的變化與淨氣的方法以施行淸除的步 驟，此方法係在進行主蝕刻後，關閉蝕刻電漿之電源，並 藉由泵浦抽真空，將反應器的壓力降低之後，再通入氣體 流，使壓力增加至約5T〇rr之後，再將壓力回復至執行飽 刻製程之條件，使聚合物因壓力的改變而予以淸除。此兩 種方法均不需額外再增加淸除的氣體源，只需以進行主蝕 刻之原氣體源即可在數秒之內淸除聚合物。其最大的差異 點在於第二種方式係利用反應器內瞬間的壓力變化，而使 聚合物可以在極短的時間內予以去除。而第一種方式則是 在相同於進行主蝕刻的壓力下進行，因此，所需耗費的時 間較第二種方式爲長。 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。 I n II I I I I I I I 訂——. I I I 錄 (請先閲讀背面之注意事項再填寫本頁) 本紙張尺度適用中國國家標準（CNS > A4規格（210X297公釐）、 1T line 1337twf.doc / 006 A7 1337twf.doc / 006 A7 Consumer Co-operation of the Central Bureau of Procurement, Ministry of Economic Affairs, Du printed B7 V. Description of the invention (/ 0) The direction is parallel to the surface of the substrate, that is, it is mutually related to the configuration of the plug Vertical, therefore, without loss of plug. Therefore, the present invention can not only shorten the process time and reduce the cost of the process, but also avoid the phenomenon of loss of metal plugs caused by excessively long overetching process. Therefore, the yield of the process can be greatly improved. The second type of gas elimination step, which is a feature of the present invention, can be performed in two ways. The first method is the method of continuous access to the original gas source, which is to turn off the power of the plasma engraving plasma and carry out the continuous supply of the original gas source. The second method is to perform the elimination step by the method of pressure change and net gas. This method is to turn off the power of the etching plasma after the main etching, and vacuum the reactor by pumping. After the pressure is reduced, a gas stream is passed in to increase the pressure to about 5 Torr, and then the pressure is returned to the condition for performing the full-saturation process, so that the polymer is eliminated due to the change in pressure. Neither method requires an additional source of gas to be eliminated, and the polymer can be removed within seconds using the original gas source for the main etch. The biggest difference is that the second method uses the instantaneous pressure change in the reactor, so that the polymer can be removed in a very short time. The first method is performed under the same pressure as the main etching. Therefore, it takes longer than the second method. 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. I n II I I I I I I I I Order-. I I I Record