SGGBf ^TWFD0C/002 A7 B7 五、發明説明（1 ) 本發明是有關於一種圖案轉移的方法與應用此法製 作的薄膜層，且特別是有關於一種利用三明治式反反光 (anti-reflection)光阻結構，配合較低成本之曝光機台 (stepper)的使用，製造出更高圖案精密度之薄膜層的方 法。 微影（photolithography)可以說是整個半導體製程中 最舉足輕重的步驟之一，凡是與金氧半（M0S)元件的結構 相關者，例如各層薄膜的圖案（pattern)及摻雜雜質的區 域，都是由微影製程所決定。整個半導體工業的元件積集 度（integration)是否能往0.25 μηι或是更小的線寬進行， 端賴於微影製程的發展是否順利而定。 經濟部中央標準局員工消費合作杜印製 (請先閲讀背面之注意事項再填寫本頁) 微影製程的曝光方式都是以光爲媒介來進行光罩圖案 的轉移，且是利用曝光機台來進行，因此，曝光機台所提 供的解析度將取決於所使用之光源的波長。當曝光機台所 使用之光源的波長越短時，整個曝光機台所能提供的最低 解析能力也就越小。但是，光源的波長越短時，曝光機台 所能提供的聚焦深度（depth of focus)就越淺，此將影響 圖案轉移的精確度。也就是說，解析度與聚焦深度是對立 的，我們必須在更短波長的光源與較深的聚焦深度間作一 取捨。 在現在商業化的半導體製程裏，比較常見的光源有所 謂的g線（g line)與i線（i line)兩種，其中，g線的波 長約爲4360A，而i線的波長約爲3650A。如前所述，當 半導體元件的積集度越來越高時，i線已無法滿足製程的 3 本紙張尺度適用中國國家橾準（CNS > A4規格（210X297公釐）SGGBf ^ TWFD0C / 002 A7 B7 V. Description of the invention (1) The present invention relates to a pattern transfer method and a thin film layer made by this method, and particularly relates to a sandwich-type anti-reflection light The resist structure, combined with the use of a lower cost exposure machine (stepper), is a method for manufacturing a thin film layer with higher pattern precision. Photolithography can be said to be one of the most important steps in the entire semiconductor manufacturing process. Those who are related to the structure of the metal oxide semi-oxide (MOS) device, such as the pattern of each thin film and the region doped with impurities, are Determined by the lithography process. Whether the integration of devices in the entire semiconductor industry can be carried out to a line width of 0.25 μm or less depends on whether the development of the lithography process is smooth. Du printing by the Ministry of Economic Affairs, Central Bureau of Standards and Staff Consumer Cooperation (please read the precautions on the back before filling out this page) The exposure method of the lithography process is to use the light as the medium to transfer the mask pattern, and the exposure machine The resolution provided by the exposure machine will depend on the wavelength of the light source used. When the wavelength of the light source used by the exposure machine is shorter, the minimum resolution capability provided by the entire exposure machine is also smaller. However, the shorter the wavelength of the light source, the shallower the depth of focus the exposure machine can provide, which will affect the accuracy of pattern transfer. In other words, the resolution and the depth of focus are opposites, and we must make a trade-off between a light source with a shorter wavelength and a deeper depth of focus. In the current commercial semiconductor manufacturing process, the more common light sources are so-called g-line (g line) and i-line (i line). Among them, the wavelength of g-line is about 4360A, and the wavelength of i-line is about 3650A . As mentioned above, when the accumulation of semiconductor elements is getting higher and higher, the i-line can no longer meet the requirements of the 3 paper standards of the manufacturing process. It is applicable to the Chinese National Standard (CNS> A4 specification (210X297 mm)
File: ( 395TWF.DOC/002 A7 B7__ 五、發明説明（2) 需求，只得發展出波長更短的光源，例如使用由 KrF(krypton flouoride laser)所發出之波長約爲 2480A 的深紫外線（deep ultra-violet ray)，作爲曝光的光源。 一般而言，以i線爲光源的曝光機台之每台售價約爲 US$200萬，而以深紫外線爲光源的曝光機台之每台售價則 約爲US$600萬。是以，是否能以較低成本的曝光機台製作 出符合需求的高精密度、高積集度產品，便成了此業者努 力的一大目標。 有鑑於此，本發明的主要目的就是在提供一種圖案的 形成方法，其利用三明治式反反光光阻結構，並配合較低 成本的曝光機台之使用，製作出符合需求的高精密度、高 積集度產品。 本發明的另一目的是提供一種圖案的形成方法，其利 用三明治式反反光光阻結構轉移圖案，使應用本發明之薄 膜層的蝕刻，可在同一蝕刻室（chamber)中進行。 本發明的又一目的是提供一種圖案的形成方法，其利 用三明治式反反光光阻結構轉移圖案，避免曝光時因光阻 層厚度不一所可能產生的反射現象。 根據本發明的上述目的，提出一種圖案的形成方法， 用以將一光罩圖案轉移至一薄膜層上。本發明至少包括下 列步驟：在薄膜層上依序形成一第一光阻層、反反光層與 第二光阻層；利用微影製程使第二光阻層形成光罩圖案； 以第二光阻層爲罩幕，定義反反光層；以反反光層爲罩幕， 定義第一光阻層；以及以第一光阻層爲罩幕，定義薄膜層。 4File: (395TWF.DOC / 002 A7 B7__ Fifth, the description of the invention (2) Demand, we must develop a light source with a shorter wavelength, such as the use of KrF (krypton flouoride laser) emitted by the deep ultraviolet (deep ultra) with a wavelength of about 2480A -violet ray), as a light source for exposure. Generally speaking, each exposure machine using the i-line as the light source is priced at about US $ 2 million, while each exposure machine using the deep ultraviolet light source is about It is US $ 6 million. Therefore, whether it is possible to produce high-precision, high-accumulation products that meet the needs with a lower-cost exposure machine has become a major goal of this industry. In view of this, the present invention The main purpose is to provide a pattern formation method that uses a sandwich-type retroreflective photoresist structure and cooperates with the use of lower-cost exposure machines to produce high-precision and high-accumulation products that meet the needs. Another object of the invention is to provide a pattern forming method which utilizes a sandwich-type retroreflective photoresist structure to transfer patterns so that the etching of the thin film layer applying the present invention can be in the same etching chamber (chamber) Another object of the present invention is to provide a pattern forming method that uses a sandwich-type retroreflective photoresist structure to transfer the pattern to avoid the reflection phenomenon that may occur due to the different thickness of the photoresist layer during exposure. According to the above of the present invention Objective To propose a pattern forming method for transferring a mask pattern to a thin film layer. The present invention includes at least the following steps: sequentially forming a first photoresist layer, a retroreflective layer and a second on the thin film layer Photoresist layer; using a photolithography process to form a second photoresist layer into a photomask pattern; using the second photoresist layer as a mask to define a reflective layer; using the retroreflective layer as a mask to define a first photoresist layer; and Use the first photoresist layer as the mask to define the film layer. 4
In J. I f— I nm—^ 泠 (請先閱讀背面之注意事項再填寫本頁) 經濟部中央標準局員工消費合作社印製 本紙張尺度適用中國國家榡準（CNS ) A4規格（210X297公釐） S〇6〇'15 95TWF.DOC/002 A7 B7 五、發明説明（彡） 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1圖是應用本發明之一種三明治式反反光光阻結構 的剖面示意圖；以及 第2A-2E圖是應用本發明以形成一閘極的製造流程剖 面圖。 實施例 傳統上，要得到一線寬〇.25μπι的圖案，通常須利用波 長約爲2480Α的深紫外線作爲曝光的光源才可實現。但 是，以深紫外線爲光源的曝光機台之聚焦深度約只有 0·5μηι，故在實際應用上存在有以下兩個問題： 1. 以深紫外線爲光源的曝光機台之售價相當昂貴’生 產成本頗高。 2. 薄膜層之寬度尺寸的縮小化，雖可因使用以深紫外 線爲光源的曝光機台而得到解決，然其高度尺寸卻並未能 等比例縮小。因此，覆蓋在薄膜層上的光阻之厚度也就無 法有效降低，通常仍較0.5μπι大。所以’即使使用以k糸 外線爲光源的曝光機台，其轉移之圖案的精確度仍會是一 個問題。 由是，請參照第1圖，本發明提出一種三明治式反反 光光阻結構，其由下而上包括一第一光阻層10、一反反光 層12與一第二光阻層14。第一光阻層10因爲在最下層， 5 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公嫠） I— _----P 裝！ (請先閲讀背面之注意事項再填寫本頁) 訂 經濟部中央標準局員工消費合作社印製 經濟部中央標準局員工消費合作社印製In J. I f— I nm— ^ Ling (please read the precautions on the back before filling out this page) The paper standard printed by the Employee Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs is applicable to the Chinese National Standard (CNS) A4 (210X297) %) S〇6〇'15 95TWF.DOC / 002 A7 B7 V. Description of the invention (彡) In order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, a preferred embodiment is given below In conjunction with the attached drawings, detailed descriptions are as follows: Brief description of the drawings: FIG. 1 is a schematic cross-sectional view of a sandwich type retroreflective photoresist structure to which the present invention is applied; and FIGS. 2A-2E are to apply the present invention to A cross-sectional view of the manufacturing process for forming a gate. Embodiments Traditionally, to obtain a pattern with a line width of 0.25 μm, it is usually necessary to use deep ultraviolet rays with a wavelength of about 2480 A as the light source for exposure. However, the depth of focus of the exposure machine using deep ultraviolet as the light source is only about 0.5μηι, so there are two problems in practical application: 1. The price of the exposure machine using deep ultraviolet as the light source is quite expensive. high. 2. The reduction in the width of the film layer can be solved by using an exposure machine that uses deep ultraviolet light as the light source, but its height cannot be reduced proportionally. Therefore, the thickness of the photoresist covering the thin film layer cannot be effectively reduced, and is usually still larger than 0.5 μm. Therefore, even if an exposure machine using a kushi outside line as a light source, the accuracy of the transferred pattern will still be a problem. Therefore, referring to FIG. 1, the present invention proposes a sandwich type retroreflective photoresist structure, which includes a first photoresist layer 10, a retroreflective layer 12 and a second photoresist layer 14 from bottom to top. Because the first photoresist layer 10 is at the bottom layer, the 5 paper scales are applicable to the Chinese National Standard (CNS) A4 specification (210X297 gong) I — _P Pack! (Please read the precautions on the back before filling out this page) Order Printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy Printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy
File: 1 395TWF.DOC/002 A7 __B7 _ 五、發明説明（¥ ) 覆蓋在欲定義（pattern)的薄膜層上表面（未顯示），故厚 度須配合其下之欲定義的薄膜層的厚度。第二光阻層14 係用以接受曝光機台的光源照射，將光罩上的圖案轉移至 非晶矽層12上。反反光層12的主要功能是避免光源穿透， 照射到第一光阻層10。也就是說，以曝光機台進行曝光 時，只有第二光阻層14會曝光，而第一光阻層10不會曝 光。故，反反光層12的材料可以是非晶砂（amorphous silicon)，或是氮化鈦（TiN)等類似特性者。一般而言， 第一光阻層10的厚度約是介於3000A-8000A之間，非晶 矽層12的厚度約是500A，而第二光阻層14的厚度約是介 於 500A-5000A之間。 應用本發明的三明治式反反光光阻結構可將光罩上的 圖案分兩次轉移至所需的薄膜層，其方法是先以使用較長 波長之光源、但較便宜的曝光機台將光罩上的圖案轉移至 圖1的反反光層12。接著再以反反光層12爲罩幕，將圖 案轉移至所需的薄膜層。接著請參照第2A-2E圖，以描述 應用本發明形成一具有小寬度尺寸之薄膜層的過程。 爲了方便說明起見，在本實施例（圖2A-2E)中係以形 成閘極爲例，但本發明並不限定只能應用在閘極的製作， 熟悉此藝者應可輕易推知至其他薄膜層的應用。 首先請參照第2A圖，提供一矽基底20 ’其上已界定 出主動區並形成有一場氧化層22。之後’在矽基底20上 形成一欲進行圖案轉移的薄膜層26 ’例如先形成一閘氧化 層24，接著在閘氧化層24上形成一薄膜層26 ’例如複晶 6 本紙張尺度適用中國國家標準（CMS ) A4規格（210X297公瘦） --------=---^ -裝------訂------冰 (請先閱讀背面之注意事項再填寫本頁) 3GGG1：5 95TWF DOC/002 A7 B7 經濟部中央梯準局員工消費合作社印装 五、發明説明（>) 矽層26。閘氧化層24與複晶矽層26例如均係利用化學氣 相沈積法所形成。複晶矽層26係欲進行圖案轉移的薄膜 層’其摻雜有雜質’且厚度例如是約2500A。然後在複晶 矽層26上形成圖1之三明治式反反光光阻結構，亦即依序 开：^成一第一光阻層28、一反反光層；30與一第二光阻層 32，例如均是利用化學氣相沈積法所形成。爲了使後續轉 移至複晶矽層26上的圖案能夠完全精確，第一光阻層28 須具備足夠的厚度。在本實施例中，反反光層3〇主要有兩 項功能：①避免曝光機台的光源穿透，照射到第一光阻層 28 ;②於後續將反反光層3〇上的圖案轉移至第二光阻層32 後’使第二光阻層32仍有足夠的厚度保護複晶矽層26， 避免圖案轉移的失真。因此，在本實施例中，第一光阻層 28的厚度例如是約7000A，而反反光層30的厚度例如約 是500A。第二光阻層32的功能主要是要將光罩上的圖案 精確轉移至反反光層30上，故其厚度例如約是介於 2000A-3000A之間即可。由於第一光阻層28極厚，故可形 成如圖2A所示的平坦表面。因是之故，反反光層30也具 有平坦的表面，當然，第二光阻層32也就不須太厚便可使 表面平坦，而使微影製程順利進行。 接著請參照第2B圖，使用例如以i線爲光源之曝光機 台進行曝光、顯影步驟，將光罩上約0·25μηι寬的圖案轉移 至第二光阻層32上，形成如圖2Β所示的形狀。 接著請參照第2C圖，以第二光阻層32爲罩幕’触刻 反反光層30，形成如圖2C所示的形狀。例如是使用乾蝕 7 本紙張^^度遑用中ΐϊ?裸準（CNS ) Α4规格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁) 裝· 訂File: 1 395TWF.DOC / 002 A7 __B7 _ V. Description of the invention (¥) Covers the upper surface of the film layer to be defined (not shown), so the thickness must match the thickness of the film layer to be defined below. The second photoresist layer 14 is used to receive the light source of the exposure machine to transfer the pattern on the photomask to the amorphous silicon layer 12. The main function of the reflective layer 12 is to prevent the light source from penetrating and irradiating the first photoresist layer 10. That is to say, when the exposure machine is used for exposure, only the second photoresist layer 14 will be exposed, and the first photoresist layer 10 will not be exposed. Therefore, the material of the reflective layer 12 may be amorphous silicon (amorphous silicon), titanium nitride (TiN) or the like. Generally speaking, the thickness of the first photoresist layer 10 is approximately between 3000A-8000A, the thickness of the amorphous silicon layer 12 is approximately 500A, and the thickness of the second photoresist layer 14 is approximately between 500A-5000A between. The sandwich-type retroreflective photoresist structure of the present invention can transfer the pattern on the reticle to the required thin film layer twice. The method is to use a light source with a longer wavelength but a cheaper exposure machine to transfer the light. The pattern on the cover is transferred to the reflective layer 12 of FIG. Then, using the reflective layer 12 as a mask, the pattern is transferred to the desired film layer. Next, please refer to FIGS. 2A-2E to describe the process of forming a thin film layer with a small width by applying the present invention. For convenience of explanation, in this embodiment (FIGS. 2A-2E), an example of forming a gate electrode is used, but the present invention is not limited to the application in the production of gate electrodes. Those skilled in the art should easily infer to other films Layer application. First, referring to FIG. 2A, a silicon substrate 20 ' is provided on which an active area has been defined and a field oxide layer 22 is formed. Afterwards, a thin film layer 26 to be pattern-transferred is formed on the silicon substrate 20, for example, a gate oxide layer 24 is formed first, and then a thin film layer 26 is formed on the gate oxide layer 24, for example, polycrystalline 6 Standard (CMS) A4 specification (210X297 male thin) -------- = --- ^ -installed ------ ordered ------ ice (please read the notes on the back before filling in This page) 3GGG1: 5 95TWF DOC / 002 A7 B7 Printed and printed by the Employees Consumer Cooperative of the Central Bureau of Economic Affairs of the Ministry of Economy V. Description of invention (>) Silicon layer 26. The gate oxide layer 24 and the polycrystalline silicon layer 26 are formed by, for example, chemical vapor deposition. The polycrystalline silicon layer 26 is a thin film layer to be pattern-transferred "doped with impurities" and has a thickness of, for example, about 2500A. Then, a sandwich-type retroreflective photoresist structure of FIG. 1 is formed on the polycrystalline silicon layer 26, that is, in order: a first photoresist layer 28, a retroreflective layer; 30 and a second photoresist layer 32, For example, they are all formed by chemical vapor deposition. In order for the pattern transferred to the polycrystalline silicon layer 26 to be completely accurate, the first photoresist layer 28 must have a sufficient thickness. In this embodiment, the retro-reflective layer 30 mainly has two functions: ① avoid the penetration of the light source of the exposure machine and irradiate the first photoresist layer 28; ② subsequently transfer the pattern on the retro-reflective layer 30 to After the second photoresist layer 32, the second photoresist layer 32 still has a sufficient thickness to protect the polycrystalline silicon layer 26 and avoid distortion of pattern transfer. Therefore, in this embodiment, the thickness of the first photoresist layer 28 is, for example, about 7000A, and the thickness of the retroreflective layer 30 is, for example, about 500A. The function of the second photoresist layer 32 is mainly to accurately transfer the pattern on the photomask to the retroreflective layer 30, so the thickness thereof may be between about 2000A-3000A, for example. Since the first photoresist layer 28 is extremely thick, a flat surface as shown in Fig. 2A can be formed. For this reason, the retroreflective layer 30 also has a flat surface. Of course, the second photoresist layer 32 does not need to be too thick to flatten the surface, and the lithography process can proceed smoothly. Next, referring to FIG. 2B, for example, using an exposure machine that uses an i-line as a light source for exposure and development steps, a pattern with a width of about 0.25 μm on the photomask is transferred to the second photoresist layer 32, as shown in FIG. 2B The shape shown. Next, referring to FIG. 2C, the retro-reflective layer 30 is etched using the second photoresist layer 32 as a mask to form a shape as shown in FIG. 2C. For example, using dry erosion 7 pieces of paper ^^ Degrees in use? Bare standard (CNS) Α4 specifications (210X297 mm) (please read the precautions on the back before filling this page)
File: 1 395TWF.DOC/002 A7 B7 五、發明説明（心） (請先閲讀背面之注意事項再填寫本頁) 刻技術，使用的設備例如是美國LAM公司出品的TCP9400 蝕刻機台，且蝕刻氣體例如是包括HBr與Ch的混合氣體。 此時，第二光阻層32也會被蝕刻而變薄，形成如圖2B所 示的厚度（編號34)，或是被蝕刻完。又，由於反反光層30 的表面平坦，故在曝光時不會產生反射現象，使得轉移後 的圖案極爲精確。 接著請參照第2D圖，以反反光層30爲罩幕，乾蝕刻 第一光阻層28，形成如圖2D所示的形狀。此乾蝕刻製程 可在同一機台中進行，只將蝕刻氣體換成例如是包括He 與（h的混合氣體。此時，反反光層30會隨著第一光阻層 28的逐漸成型而自然被蝕刻去除，當然，第二光阻層32 如有殘餘也會被蝕刻殆盡。 最後請參照第2E圖，以第一光阻層28爲罩幕，乾蝕 刻複晶矽層26，形成如圖2E所示的閘極36，完成0.25μηι 寬的圖案之轉移。此乾蝕刻製程亦在同一機台中進行，只 是將蝕刻氣體又換成例如是包括HBr與Ch的混合氣體。 綜上所述，熟悉此藝者可知應用本發明具有如下的優 點： 經濟部中央標準局貝工消費合作社印製 1. 可以以低成本製作出約0.25μιη寬的圖案。 2. 圖案轉移過程中的蝕刻步驟，均可在同一蝕刻室中 進行。 3. 第二光阻層與反反光層可在圖案轉移的蝕刻過程中 自然消失，不須增加額外的製程步驟去除之。 4. 由於反反光層的表面平坦，故避免了曝光時的光反 8 本紙張尺度逋用中國國家標準（CNS ) Α4規格（21ΟΧ 297公H " 5TWF.DOC/002 A7 B7 五、發明説明（〇) 射問題。 雖然本發明已以一些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，當可作些許之更動與潤飾，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------( (請先閲讀背面之注意Ϋ項再填寫本頁) 經濟部中央標準局員工消費合作社印製 本紙張尺度適用中國國家揉準（CNS )八4规格（210X297公釐）File: 1 395TWF.DOC / 002 A7 B7 V. Invention description (heart) (please read the precautions on the back before filling in this page) Engraving technology, the equipment used is, for example, the TCP9400 etching machine produced by American LAM company, and etching The gas is, for example, a mixed gas including HBr and Ch. At this time, the second photoresist layer 32 will also be etched and thinned to a thickness (No. 34) as shown in FIG. 2B, or etched. In addition, since the surface of the retroreflective layer 30 is flat, no reflection phenomenon occurs during exposure, making the transferred pattern extremely accurate. Next, referring to FIG. 2D, using the reflective layer 30 as a mask, the first photoresist layer 28 is dry-etched to form a shape as shown in FIG. 2D. This dry etching process can be performed in the same machine, and only the etching gas is replaced by a mixed gas including, for example, He and (h. At this time, the reflective layer 30 will be naturally formed as the first photoresist layer 28 is gradually formed Etching is removed, of course, the second photoresist layer 32 will be etched away if there is any residue. Finally, please refer to FIG. 2E, using the first photoresist layer 28 as a mask, dry etching the polycrystalline silicon layer 26, as shown in the figure The gate 36 shown in FIG. 2E completes the transfer of a 0.25 μm wide pattern. This dry etching process is also performed in the same machine, except that the etching gas is replaced with a mixed gas including HBr and Ch, for example. Those who are familiar with this artist know that the application of the present invention has the following advantages: Printed by the Beigong Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 1. Can produce a pattern with a width of about 0.25μιη at a low cost. 2. The etching steps in the pattern transfer process are all It can be performed in the same etching chamber. 3. The second photoresist layer and the retroreflective layer can disappear naturally during the pattern transfer etching process, and no additional process steps are needed to remove it. 4. Since the surface of the retroreflective layer is flat, So avoid The light reflection at the time of exposure 8 The paper scale adopts the Chinese National Standard (CNS) Α4 specification (21 Ο 297 public H " 5TWF.DOC / 002 A7 B7. V. Description of the invention (〇) The problem of shooting. Although the present invention has taken some The preferred embodiment is disclosed as above, but it is not intended to limit the present invention. Anyone who is familiar with this skill can make some changes and modifications within the spirit and scope of the present invention, so the scope of protection of the present invention is Subject to the definition of the scope of the attached patent application. ---- 1 .----- (. 装 ------ 定 ------ ((Please read the note Ϋ item on the back (Fill in this page again) The paper standard printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs is applicable to the Chinese National Standard (CNS) 84 specifications (210X297 mm)