經濟部中央標準局員工消費合作社印製 473815 4276twf.doc/〇Q3 A7 ________B7 五、發明説明u ) 本發明是有關於一種半導體製造的微影 (Photolithography)製程，且特別是有關於—種增加微影解 析度的方法。 半導體的製程一般區分爲四個模組（module)，包 括擴散（diffUsion)、蝕刻（etching)、薄膜（化匕fUm)與黃光 (photo)，其中的黃光模組即是負責微影製程，主要的工作 即是將光罩（mask)上的圖案轉移到晶片上，以提供蝕刻模 組良好的蝕刻圖案，或是提供薄膜模組良好的摻雜（iniplant) 圖案。由於凡是與金氧半導體（M0S)元件的結構相關的， 如·各層薄膜的圖案（pattern)及摻質（d〇pants)的區域，都 是由Μ影步驟來決定。因此，我們通常以一個製程所需要 經過的微影次數，或是所需要的光罩數量，來表示這個製 程的難易程度。此外，整個半導體工業的元件積集度 (integration)，是否能往更小的線寬進行，也端賴於微影製 程的發展是否順利而定。 在在微影製程中，曝光的解析度（resolution)及聚焦深 度（depth of f0CUS，D〇F)是微影品質的重要指標。由於半導 體積集度的增加需要更高的解析度，解決的方法之一就是 使用波長較短的光源，比如使用由Kr雷射所發出波長爲 248〇A的深紫外線作爲曝光的光源，當半導體進入深次微 米（deep sub-micron)尺寸的製程時，微影製程首先受到考 ’譬如曝光光源的波長已經逐漸接近所要轉移的圖案尺 寸’如何準確的完成圖案轉移的工作，確實需要許多的努 力。 3 本紙張尺度適用中國國家標隼（CNS ) A4規格（210X297公釐） ' I^--------d衣-- (請先閱讀背面之注意事項再填寫本頁} 、=口 P. 473815 4276twf.d〇 c / 〇 0 8 A7 B7 五、發明説明（^) 另外’從製程整合或開發的觀點來看，由於元件尺寸 越來越小’元件設計的尺寸大小所能容許的誤差(tolerance) 也越來越小，並且已逐漸接近製程儀器（比如步進機stepper 或掃描機scanner)本身解析度的極限。也就是說，在深次 微米:尺寸的製程中儘管製程不發生任何人爲因素或製程環 境的改變’要製造出符合元件設計所能容許的誤差範圍的 元件，是愈來愈困難了。 微影製程的技術雖然很複雜，其基本原理卻很簡單。. 首先在晶片上面覆上一層光阻，在曝光（exposure)的步驟 中’入射光透過光罩進行選擇性的感光，便會將光罩上的 圖案轉移到光阻上面。進行曝光所需要的工具除了光源以 夕和’還有用來提供線路圖案以便執行圖案轉移的光罩，由 於光卓的線距寬（pitch)—定，·形成在晶片上的線距寬就固 定’所謂的線距寬是指一線寬加上一線距（space)，線距與 線寬的大小均受到光源解析度的限制，所以最緊密的元件 圖案具有相等的線寬與線距。 如弟1圖所不，其繪不爲習知的一種罩幕圖案的佈局 圖。標號10與12表示的區域是在微影製程中被曝光與顯 影的部分，此區域的寬度即爲線寬/，而兩個區域之間的 距離爲線距s，由於受制於光源解析度，故具有相等線寬/ 與線距^。 習知一種縮小線距的方法，是形成一硬罩幕層（hard mask)覆蓋欲定義的目標層(target layer)，此硬罩幕層譬如 爲氧化矽層，而此目標層譬如爲多晶矽層。將光罩上的圖 4 本紙張尺度適用中國國家標準（CNS ) A4規格（21〇Χ：297公釐） --------- (請先閲讀背面之注意事項再填寫本頁)Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 473815 4276twf.doc / 〇Q3 A7 ________B7 V. Description of the invention u) The present invention relates to a photolithography process for semiconductor manufacturing, and in particular, it relates to an increase in microlithography. Shadow resolution method. The semiconductor manufacturing process is generally divided into four modules, including diffUsion, etching, thin film (fUm), and yellow light. Among them, the yellow light module is responsible for the lithography process, mainly The task is to transfer the pattern on the mask to the wafer to provide a good etching pattern for the etching module or a good iniplant pattern for the thin film module. As it is related to the structure of the metal oxide semiconductor (MOS) device, such as the pattern and doped regions of each layer of film, it is determined by the M shadow step. Therefore, we usually use the number of lithography required for a process or the number of photomasks to indicate the difficulty of the process. In addition, whether the integration of components in the entire semiconductor industry can be made to a smaller line width depends on whether the development of the lithography process is smooth. In the lithography process, the resolution of the exposure and the depth of focus (DOF) are important indicators of the quality of the lithography. As the increase in semiconductor accumulation requires higher resolution, one of the solutions is to use a light source with a shorter wavelength, such as using deep ultraviolet light with a wavelength of 2480A emitted by Kr laser as the light source for exposure. When entering a deep sub-micron size process, the lithography process is first tested 'for example, the wavelength of the exposure light source has gradually approached the size of the pattern to be transferred' How to accurately complete the pattern transfer work does require a lot of effort . 3 This paper size applies to China National Standard (CNS) A4 specification (210X297 mm) 'I ^ -------- d clothing-(Please read the precautions on the back before filling this page} 、 = 口P. 473815 4276twf.d〇c / 〇0 8 A7 B7 V. Description of the invention (^) In addition, 'from the point of view of process integration or development, the component size is getting smaller and smaller' The tolerance is also getting smaller and smaller, and it is gradually approaching the resolution limit of the process instrument (such as stepper or scanner). That is to say, in the deep sub-micron: size process, although the process does not occur Any man-made factors or changes in the process environment 'It is becoming more and more difficult to manufacture components that meet the tolerance range allowed by component design. Although the technology of lithography is very complicated, the basic principle is very simple .. First of all A layer of photoresist is coated on the wafer. In the exposure step, the incident light is selectively exposed through the photomask, and the pattern on the photomask is transferred to the photoresist. In addition to the tools required for exposure Light source And 'There is also a mask for providing a line pattern in order to perform a pattern transfer. Since the pitch of the light line is fixed, the line width formed on the wafer is fixed.' The so-called line width refers to a line width Adding a line spacing (space), the size of line spacing and line width are limited by the resolution of the light source, so the closest component pattern has equal line width and line spacing. As shown in Figure 1, it is not a custom to draw A known layout of a mask pattern. The areas indicated by reference numerals 10 and 12 are the parts exposed and developed during the lithography process. The width of this area is the line width /, and the distance between the two areas is the line. The distance s, due to the resolution of the light source, has the same line width / space ^. It is known that a method to reduce the line distance is to form a hard mask covering the target layer to be defined. ), The hard cover curtain layer is, for example, a silicon oxide layer, and the target layer is, for example, a polycrystalline silicon layer. As shown in Figure 4 on the reticle, the paper size applies the Chinese National Standard (CNS) A4 specification (21 ×: 297 mm) --------- (Please read the notes on the back before filling This page)
、1T 經濟部中央標準局員工消費合作社印製 473815 經濟部中央標準局員工消費合作社印製 五、發明説明（々） 案轉移至硬罩幕層，定義此罩幕層。然後形成一層共形層 (conformal layer)覆蓋已定義的硬罩幕層。利用回蝕刻法在 已定義的硬罩幕層之側壁形成間隙壁（spacer) ’利用包括 間隙壁的硬罩幕層作爲罩幕，對目標層進行蝕刻’由於間 隙壁擴大了線寬的尺寸，所以形成的目標層之圖案具有較 小的線距。也就是說，在縮小線距的同時也增加了線寬尺 寸，這有時並不是製程所期望見到的。 因此，本發明提供一種增加微影解析度的方法’將變 更光罩圖案的設計，將原本的光罩圖案切割成兩個部分’ 分置於兩個以上不同的光罩上。在進行微影製程時，在目 標層上覆蓋第一罩幕，透過第一罩幕進行曝光’以將第一 光罩上的圖案轉移到目標層上。移除第一罩幕’續將第二 罩幕覆蓋在目標層上，進行曝光以將第二罩幕上的圖案轉 移到目標層上。之後，再進行顯影的步驟’以在目標層上 呈現預定的圖案。 本發明提供之方法並不改變光覃上圖案的線寬’但圖 案之間的線距可透過分次曝光加以拉近’其優點在於不需 要使用新的光源，只要對光罩進行修改就可以提昇原有曝 光的解析能力，並進一步縮小元件設計需要的面積’以提 高元件的積集度。 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： 5 (請先閱讀背面之注意事項再填寫本頁) 丁 本紙張尺度適用中國國家標準（CNS ) A4規格（210Χ297公釐） 473815 4276twf.d〇c/008 A7 B7 經濟部中央標準局員工消費合作社印製 五、發明説明（u) 第1圖繪示爲習知的一種罩幕圖案的佈局圖； 第2A圖繪示依照本發明一較佳實施例的第一罩幕佈 局圖， 第2B圖繪示依照本發明一較佳實施例的第二罩幕佈 局圖， 第3圖繪示依照本發明一較佳實施例’顯影後之佈局 圖；以及 第4圖繪示爲依照本發明一較佳實施例的一種微影步 驟流程簡示圖。 圖示標記說明： 10，12,20a，20b 曝光與顯影的區域 IX 線寬 s，S 線距 20 第一罩幕上的圖案 22 第二罩幕上的圖案 實施例 本發明係將習知佈局中祖鄰的圖案分成至少兩部分， 分別繪製在第一罩幕與第二罩幕上，如第2A圖與第2B 圖所示。第2 A圖中標號20所表示的區域爲第一罩幕上的 佈局圖；第2B圖中標號22所表示的區域則爲第二罩幕上 的佈局圖。 微影的基本製程包括光阻塗佈（coating)、曝光（exposure) 以及顯影（development)等三大步驟。第4圖所示爲本發明 之一種微影製程的流程圖◦以下敘述爲本發明提供之微影 6 本紙張尺度適用中國國家標準（CNS ) A4規格（210父297公釐1 " " (請先閱讀背面之注意事項再填寫本頁) 訂 f 473815 經濟部中央標準局員工消費合作社印製 A7 4276twf.doc/008 ΌΊ 〇 / 五、發明説明（g ) 製程以及罩幕的產生方式，請同時參照第4圖之流程圖， 並依序配合第2A圖、第2B圖與第3圖。 首先，先將習知佈局中相鄰的圖案（請參照第1圖）分 爲兩個部分，分置於第一罩幕與第二罩幕上，如第2A圖 所述的圖案20以及第2B圖所不的圖案22。 提供目標物，比如一晶片，如標號40所示。接著，如 標號42所示，在目標物上覆蓋一層光阻層，覆蓋的方式 比如爲旋塗式塗佈法（spin coating)，以使光阻層在晶片上 分布較爲均勻。光阻主要由樹脂(resin)、感光劑（sensitizer) 及溶劑（solvent)混合而成，其中的感光劑爲一種光活性 (photoactivity)極強的化合物，經由光照射後會產生化學變 化，變成容易解離的結構，或是結構變得更強。 如標號44所示，進行第一次曝光，將第2A圖所示的 第一罩幕上之圖案_20轉移到光阻層上；接著如標號46所 示，進行第二次曝光，將第2B圖所示之第二罩幕上的圖 案22轉移到光阻層上。在第二次曝光時，可利用對準的 方式調整第二罩幕與光阻的相對位置，以控制圖案22與 圖案20之間的距離，也就是所謂的線距。 如標號48所示，將第二罩幕上的圖案22轉移到光阻 層以後，進行顯影的步驟，以便將光阻層所轉移的潛在圖 案顯現出來。爲了避免光阻因爲其他可能的副反應（side reaction)而改變其化學結構，經過曝光的光阻應盡速的進 行圖案的顯影。 顯影後之圖案如第3圖所示，第一罩幕的圖案20a與 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) 473815 4276twf . doc/008 ____---------------- 五、發明説明（t ) 第二罩幕之圖案22b之線寬L與習知相同，但是由於在第 二次曝光時，可利用對準的方式調整第二罩幕與光1阻的相 對位置，以控制圖案20a與圖案22b之間的距離’也就是 所謂的線距S可被進一步的縮短，甚至小於光源解析度° 因此，在本發明中圖案的解析度並不單單由 的緊密度控制，也可以由罩幕對準的精確度加以調整；特 別是應用在提高銅的金屬鑲嵌的製程之積集度上’有顯著 的助益。因爲欲曝光的圖案被分置在兩個以上的罩幕上’ 呈現在光阻層上的佈局可變得更爲緊密，故可進一步的提 高設計規則（design rule)。 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。 J--------— (請先閱讀背面之注意事項再填寫本頁) p -5-X» ^--- 經濟部中央標準局員工消費合作社印製 適Printed by the 1T Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 473815 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the Invention (々) The plan was transferred to the hard cover layer, and this cover layer was defined. A conformal layer is then formed to cover the defined hard mask curtain layer. The spacer is formed on the side wall of the hard mask layer defined by the etch-back method. 'Using the hard mask layer including the gap wall as the mask, the target layer is etched.' As the size of the line width is enlarged by the gap wall, Therefore, the pattern of the formed target layer has a smaller line pitch. In other words, while reducing the line spacing, the line width is also increased, which is sometimes not expected in the manufacturing process. Therefore, the present invention provides a method for increasing the lithographic resolution, which is to change the design of the reticle pattern, cut the original reticle pattern into two parts, and distribute it on two or more different reticles. During the lithography process, a first mask is covered on the target layer, and exposure is performed through the first mask 'to transfer the pattern on the first mask to the target layer. Remove the first mask 'and continue to cover the second mask on the target layer, and perform exposure to transfer the pattern on the second mask to the target layer. After that, a development step 'is performed to present a predetermined pattern on the target layer. The method provided by the present invention does not change the line width of the pattern on the light frame, but the line spacing between the patterns can be narrowed by fractional exposure. The advantage is that it does not require the use of a new light source, as long as the mask can be modified. Improve the resolution of the original exposure, and further reduce the area required for component design 'to increase component accumulation. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is exemplified below and described in detail with the accompanying drawings' as follows: A brief description of the drawings: 5 (Please read first Note on the back, please fill in this page again.) The paper size of this paper is applicable to Chinese National Standard (CNS) A4 specification (210 × 297 mm) 473815 4276twf.d〇c / 008 A7 B7 Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs Explanation (u) FIG. 1 is a layout diagram of a conventional mask pattern; FIG. 2A is a layout diagram of a first mask according to a preferred embodiment of the present invention, and FIG. 2B is a diagram illustrating a layout according to the present invention. A second mask layout diagram of a preferred embodiment, FIG. 3 illustrates a layout diagram after development according to a preferred embodiment of the present invention; and FIG. 4 illustrates a layout diagram according to a preferred embodiment of the present invention. Lithography step flow diagram. Description of the pictograms: 10, 12, 20a, 20b Exposed and developed areas IX Line width s, S Line pitch 20 Pattern on the first screen 22 Pattern on the second screen Example embodiments of the present invention will be a conventional layout The pattern of the middle ancestors is divided into at least two parts, which are respectively drawn on the first mask and the second mask, as shown in Figures 2A and 2B. The area indicated by reference numeral 20 in Fig. 2A is the layout diagram on the first mask; the area indicated by reference numeral 22 in Fig. 2B is the layout diagram on the second mask. The basic process of lithography includes three major steps: photoresist coating, exposure, and development. Figure 4 shows the flow chart of a lithographic process of the present invention. ◦ The following description provides the lithographic process provided by the present invention. 6 The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 parent 297 mm 1 " " (Please read the notes on the back before filling this page) Order f 473815 Printed by the Consumers Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs A7 4276twf.doc / 008 〇 〇 / V. Description of the invention (g) Process and production method of the mask, Please refer to the flowchart in Figure 4 at the same time, and cooperate with Figures 2A, 2B and 3 in order. First, first divide the adjacent patterns in the conventional layout (please refer to Figure 1) into two parts. , Placed on the first cover and the second cover, as shown in the pattern 20 shown in Figure 2A and the pattern 22 not shown in Figure 2B. Provide a target, such as a wafer, as shown at 40. Then, As shown by reference numeral 42, a photoresist layer is coated on the target, such as a spin coating method, so that the photoresist layer is more uniformly distributed on the wafer. The photoresist is mainly made of resin. (resin), sensitizer and solvent The photosensitizer is a compound with extremely strong photoactivity, which undergoes chemical change after irradiation with light, and becomes a structure that is easily dissociated, or the structure becomes stronger. As shown by reference numeral 44, the first step is performed. In the second exposure, the pattern _20 on the first mask shown in FIG. 2A is transferred to the photoresist layer; then, as indicated by reference numeral 46, a second exposure is performed, and the second mask shown in FIG. 2B is performed. The pattern 22 on the top is transferred to the photoresist layer. During the second exposure, the relative position of the second mask and the photoresist can be adjusted by alignment to control the distance between the pattern 22 and the pattern 20, that is, The so-called line spacing. As shown by reference numeral 48, after the pattern 22 on the second mask is transferred to the photoresist layer, a development step is performed so as to show the potential pattern transferred by the photoresist layer. In order to avoid photoresist because Other possible side reactions change its chemical structure, and the photoresist after exposure should be developed as soon as possible. The pattern after development is shown in Figure 3, and the patterns 20a and 7 of the first mask are developed. Paper size applicable to China Standard (CNS) A4 (210X297 mm) (Please read the notes on the back before filling out this page) 473815 4276twf. Doc / 008 ____---------------- V. Invention Explanation (t) The line width L of the pattern 22b of the second mask is the same as the conventional one, but since the relative position of the second mask and the photoresistor can be adjusted during the second exposure, The distance 'between the pattern 20a and the pattern 22b, that is, the so-called line distance S can be further shortened, even smaller than the light source resolution °. Therefore, the resolution of the pattern in the present invention is not only controlled by the tightness, it can also be Adjusted by the accuracy of the mask alignment; especially applied to improve the accumulation of copper's metal damascene process has a significant benefit. Because the pattern to be exposed is divided into two or more masks, the layout presented on the photoresist layer can be made closer, so the design rule can be further improved. 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. J --------— (Please read the notes on the back before filling this page) p -5-X »^ --- Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs
I 29I 29