494473 五、發明說明（1) 發明領域： 本發明揭露有關於一種微影製程之微影透鏡檢驗方 法，特別是指一種利用雜散光之特性，配合以被驗之微影 透鏡利用特別設計之光罩為罩幕照射負型光阻檢驗，以檢 驗微影透鏡抗反射塗層的均勻度。 發明背景： 積體電路製程係將多層薄膜結構架構在一半導體基材 上，各層薄膜在沉積後以微影配合蝕刻製程來獲得預定之 電路圖案，是一必要之手段。為達到所需之圖案，使用蝕 刻罩幕是最直接的方法。而钱刻罩幕常用的方式有兩種， 一種為直接利用光阻搭配光罩，再利用微影製程的照光 (exposure)及顯影（developer)步驟而形成光阻圖案。另 一者便是形成薄膜圖案的方法是利用硬式罩幕。但即使是 硬式罩幕做為蝕刻罩幕，硬式罩幕的形成，也是需要光阻 層，微影製程的照光及顯影步驟而形成光阻圖案才行。換 言之，光阻圖案，是所有蝕刻以形成薄膜圖案的基礎。有 精確光罩圖案轉移至光阻圖案，才能有精確的線寬 (critical dimension)0 而微影製程的關鍵技術又和光罩的品質、光罩的設 計’乃至微影透鏡的品質都很有關係。光罩的品質決定於494473 V. Description of the invention (1) Field of the invention: The present invention discloses a lithographic lens inspection method for a lithographic process, in particular, a method that utilizes the characteristics of stray light and cooperates with the lithographic lens under test to use specially designed light. The mask is a negative photoresistance test for mask irradiation to check the uniformity of the anti-reflection coating of the lithographic lens. Background of the Invention: The integrated circuit manufacturing process is to build a multilayer thin film structure on a semiconductor substrate. After the deposition of each layer of thin film, a predetermined circuit pattern is obtained by lithography and an etching process, which is a necessary means. To achieve the desired pattern, an etch mask is the most direct method. There are two commonly used methods for money engraving masks. One is to form a photoresist pattern by directly using a photoresist with a photomask, and then using the exposure and development steps of the lithography process. Another method is to form a thin film pattern by using a hard mask. However, even if a hard mask is used as an etching mask, the formation of a hard mask requires a photoresist layer, a photolithography process, and a photo development step to form a photoresist pattern. In other words, the photoresist pattern is the basis of all etching to form a thin film pattern. Only when the precise mask pattern is transferred to the photoresist pattern can the precise line width be critical. The key technology of the lithography process is related to the quality of the mask, the design of the mask, and even the quality of the lithographic lens. . Mask quality depends on
第4頁 494473 五、發明說明（2) 是否光罩所含缺陷數有關。而光罩的設計，則和鄰接效應 (p r ο X i m i t y e f f e c t)有關。而微影透鏡的品質則和透鏡鏡 片及透鏡套筒内部所塗佈之抗反射塗層（ARC )有關。 一般而言，透鏡套筒内部的抗反射塗層，係用以吸收 來自晶圓反射回來的光，上述反射光一般稱為雜散光 (stray light)。請參考圖一所示的示意圖。圖示一光罩 1 0、一透鏡2 0及一晶圓3 0在一步進平台4 0上。晶圓3 0所接 受的光除了來自微影機投射光源4外，並有部分的雜散光 5。透鏡套筒内部所塗佈之抗反射塗層即是利用以吸收雜 散光5。若抗反射塗層塗佈均勻時，將可使照射於晶圓3 0 的雜散光5最小。但若雜散光5未被完全吸收時，顯然就有 -非預期的光照射於光阻上。而使得線寬不正確。例如對正 型光阻而言，被雜散光照射的光阻，其線寬將會比原預設 ‘ 的寬度小。反之，對負型光阻而言，被雜散光照射的光 阻，其線寬將會比原預設的寬度大。 為防止雜散光造成線寬的不正確，顯然地，微影透鏡 的品質就需要加以注意。習知技術檢驗微影透鏡的方法， 係間接地利用正型光阻在被經由光罩、微影透鏡的光照光 ¥ 於正型光阻後，顯影、再量取線寬的變化（即線寬縮小程 度），以評定是否微影透鏡的可用性。然而，由於受到光 罩圖案的差異性，照光能量大小的影響（愈強的光將使得 光阻線條邊緣的圖案也反應，此即鄰接效應）。這種檢驗Page 4 494473 V. Description of the invention (2) Whether the number of defects in the photomask is related. The design of the reticle is related to the adjacency effect (p r ο X i m i t y e f f e c t). The quality of the lithographic lens is related to the anti-reflection coating (ARC) applied on the inside of the lens lens and lens sleeve. Generally speaking, the anti-reflection coating inside the lens sleeve is used to absorb the light reflected from the wafer. The reflected light is generally called stray light. Please refer to the diagram shown in Figure 1. A photomask 10, a lens 20, and a wafer 30 are shown on a stepping platform 40. The light received by the wafer 30 is in addition to the projection light source 4 from the lithography machine, and part of the stray light 5 is received. The anti-reflection coating applied inside the lens sleeve is used to absorb stray light5. If the anti-reflection coating is uniformly applied, the stray light 5 irradiating the wafer 30 can be minimized. But if the stray light 5 is not completely absorbed, it is obvious that-unexpected light is irradiated on the photoresist. This makes the line width incorrect. For example, for a positive type photoresist, the line width of the photoresist irradiated by stray light will be smaller than the original preset width. Conversely, for negative photoresists, the line width of the photoresist illuminated by stray light will be larger than the original preset width. To prevent stray light from causing incorrect line widths, obviously the quality of the lithographic lens needs attention. The method of testing the lithographic lens by conventional techniques is to indirectly use the positive photoresist to develop the light after passing the light from the photomask and the lithography lens to the positive photoresist. Width reduction) to assess the availability of lithographic lenses. However, due to the difference in the mask pattern and the amount of light energy (the stronger the light, the pattern on the edge of the photoresist line will also reflect, this is the adjacency effect). This test
第5頁 494473 五、發明說明（3) 方法，因此，並不能真正反應微影透鏡真正的品質。 _ 本發明之目的因此，提供一較為科學的方法，不但可 · 以檢驗微影透鏡的可用性，且若配合對同一光罩，不同像 場施以不同的曝光能量檢驗板可以提供別每一微影透鏡的 特性參數。 發明目的及概述： 本發明目的係提供一種檢驗微影透鏡抗反射塗層吸收 雜散光能力的檢驗方法。藉由本發明的方法，可了解該微 透鏡適合用的曝光能量範圍。而避免使用對該微透鏡選用 、 不當之曝光量。 本發明方法，至少包含以下步驟：首先，提供一光 罩，光罩包含2x 2、4x 4、6x 6···等π偶數個 x偶 數個''晶片等晶元於其中，以做為照光用之光罩，以使得 該光罩之中心係落於晶元與晶元之間的切割道上；接著， 利用該光罩及待檢測之微透鏡，照光於一塗佈負型光阻的 半導體基板上；隨後，顯影該光阻；再檢驗半導體基板上 # 切割道之殘留光阻量，即可得知雜散光對微影透鏡抗反射 塗層均勻情況，及吸收雜散光能力。本發明更進一步利用 不同之照光量，經透鏡對光阻曝光，而可以得知被檢驗之 微透鏡適合用的曝光能量範圍。Page 5 494473 V. Description of the invention (3) Method, therefore, it cannot really reflect the true quality of the lithographic lens. _ The purpose of the present invention is therefore to provide a more scientific method, which can not only check the availability of lithography lenses, but if used with the same reticle, different exposure fields with different exposure energies can provide different micrometers. The characteristic parameters of the shadow lens. OBJECTS AND SUMMARY OF THE INVENTION The object of the present invention is to provide a method for inspecting the ability of the anti-reflection coating of the lithographic lens to absorb stray light. By the method of the present invention, the suitable exposure energy range of the microlens can be understood. Avoid using improper exposure of the microlens. The method of the present invention includes at least the following steps: First, a photomask is provided, and the photomask includes 2x2, 4x4, 6x6, etc., and π even number x even number of `` wafers '' and other wafers are used as illumination light. The photomask is used so that the center of the photomask falls on the cutting path between the wafer and the wafer. Then, the photomask and the microlens to be detected are used to illuminate a semiconductor coated with a negative photoresist. On the substrate; then, develop the photoresist; and then check the remaining photoresist amount of the #cut track on the semiconductor substrate, and you can know the stray light uniformity of the anti-reflection coating of the lithographic lens and the ability to absorb stray light. The present invention further uses different amounts of light to expose the photoresist through the lens, and can know the suitable exposure energy range of the microlens to be tested.
第6頁 494473 五、發明說明（4) 發明詳細說明： _ 有鑑於如發明背景所述，傳統微影透鏡抗反射塗層是 否仍有效吸收來自晶圓反射回來的雜散光係透過照光後正 光阻線寬尺寸縮減的程度，了解微影透鏡的品質。然而上 述習知技術，正型光阻線寬尺寸除了受到雜散光影響外， 光罩鄰接效應之影響，是另一重要影響因素，換言之，傳 統檢驗方法並不能真正顯示微影透鏡抗反射塗層的品質。 因此，本發明為區隔來自雜散光與曝光光源所產生之 影響，應用的方法係使用負型光阻，一如熟悉相關技藝之 、 人士所知，負型光阻只要照光，顯影後即可留下光阻。因 此若原光罩不被照光處，顯影後理應不會有光阻留下。利 ^ 用上述原理後及配合應用一像場具有偶數個晶片之光罩， 可因此解決傳統方法之問題。 發明人發現，來自晶圓反射光，若未被微影透鏡内套 筒所塗佈之抗反射塗層所吸收，則由·於雜散光5常出現於 像場（image field)中心處。因此，當使用一光罩（或稱一 > 像場）具有偶數個晶元（d i e )之光罩，例如每單一光罩具有 2 X 2、4 X 4、6 X 6···等π偶數個 X 偶數個π晶片 等，則晶元與晶元之間的切割道（s c r i b e 1 i n e )處，就預 設的照光條件下是不會被照光的。換言之，該處之負型光Page 6 494473 V. Description of the invention (4) Detailed description of the invention: _ In view of the fact that, as stated in the background of the invention, the anti-reflection coating of the traditional lithographic lens still effectively absorbs the stray light reflected from the wafer. How much the line width size has been reduced to understand the quality of the lithography lens. However, in the above-mentioned conventional technology, in addition to the effect of stray light on the positive photoresistance line size, the influence of the abutment effect of the mask is another important factor. In other words, the traditional inspection method cannot really display the anti-reflection coating of the lithographic lens. Quality. Therefore, the present invention is to separate the influence from stray light and exposure light source. The method used is to use a negative photoresist. As is known to those skilled in the related art, the negative photoresist only needs to be illuminated and developed. Leaving photoresist. Therefore, if the original mask is not illuminated, there should be no photoresist left after development. The above-mentioned principle and the application of a photomask with an even number of wafers in an image field can solve the problems of the traditional method. The inventor found that the reflected light from the wafer, if not absorbed by the anti-reflection coating applied to the inner sleeve of the lithographic lens, is caused by stray light 5 which often appears at the center of the image field. Therefore, when a photomask (or a > image field) is used, which has an even number of dies, for example, each single photomask has 2 X 2, 4 X 4, 6 X 6 ... An even number of X even number of π wafers, etc., the scribe 1 ine between the wafer and the wafer will not be illuminated under the preset illumination conditions. In other words, the negative light there
第7頁 494473 五、發明說明（5) 阻可以完全被顯影劑所顯開。然而由於雜散光的貢獻，將 可以觀察到切割道處有光阻殘留。例如圖二所示的影像係 以光學顯微鏡的應用上述之本發明方法，觀察到殘留之光 阻。 圖二中1 0 0係接觸墊（b ο n d i n g p a d )， 1 1 0則係切割 道。殘留光阻1 2 0的情況如圖所示。相較於傳統微影透鏡 檢驗方法，必須量取尺寸變化，因此，非得使用掃瞄式電 子顯微鏡（S Ε Μ )以量度不可。本發明只需在一般光學顯微 鏡下觀察檢驗透鏡之抗反射塗層品質，當然比傳統方法可 精準且方便。 由於雜散光的大小，係和照光能量有關。為進一步了 解且量化微影透鏡之抗反射塗層的品質，以避免選用可能 產生殘留光阻的照光能量對微透鏡照光。本發明係利用在 一晶圓上設計陣列式排列像場1 4 0。如圖三所示，每一像 場1 4 0係以等差級數之照光能量照射。例如像場1 4 0 a以 3 0 m j能量照光，像場1 4 0 b以3 2 m j能量照光，像場1 4 0 c以 3 4m j能量照光等等，依序對每一相鄰之像場增加照光能 量 ° 因此，若微影透鏡之抗反射塗層不均勻，無法吸收反 射光時，每一像場中心便會有不等程度之光阻殘留（當 然，測試時係使用負型光阻）。由此，便可得知該透鏡之Page 7 494473 V. Description of the invention (5) The resistance can be completely revealed by the developer. However, due to the contribution of stray light, it will be possible to observe the presence of photoresist at the cutting line. For example, the image shown in Fig. 2 is obtained by applying the above-mentioned method of the present invention with an optical microscope, and the residual photoresist is observed. In Figure 2, 100 is the contact pad (b ο n d i n g p a d), and 1 1 0 is the cutting path. The situation of the residual photoresist 1 2 0 is shown in the figure. Compared with the traditional lithographic lens inspection method, it is necessary to measure the dimensional change. Therefore, it is necessary to use a scanning electron microscope (SEM) to measure. The invention only needs to observe and inspect the quality of the anti-reflection coating of the lens under a general optical microscope, and of course, it is more accurate and convenient than the traditional method. Due to the amount of stray light, it is related to the energy of the light. In order to further understand and quantify the quality of the anti-reflection coating of the lithographic lens, in order to avoid irradiating the microlens with illumination energy that may cause residual photoresistance. The present invention utilizes the design of an arrayed image field 140 on a wafer. As shown in Fig. 3, each image field 140 is irradiated with light energy of an equal number of steps. For example, image field 1 4 0 a is illuminated with 30 mj energy, image field 1 4 0 b is illuminated with 3 2 mj energy, image field 1 4 0 c is illuminated with 3 4m j energy, and so on. The image field increases the illumination energy °. Therefore, if the anti-reflection coating of the lithographic lens is not uniform and cannot absorb the reflected light, there will be varying degrees of photoresistance at the center of each image field (of course, a negative type is used during the test) Photoresist). From this, we can know the
第8頁 494473 五、發明說明（6) 特性參數（即最可能產生殘留光阻之照光能量範圍。而避 免使用該微影透鏡於該能量範圍下照光。必要時更換該微 透鏡之抗反射塗層。 以上所述僅為本發明之較佳實施例而已，並非用以限 定本發明之申請專利範圍；凡其它未脫離本發明所揭示之 精神下所完成之等效改變或修飾，均應包含在下述之申請 專利範圍内。 ❿Page 8 494473 V. Description of the invention (6) Characteristic parameters (that is, the light energy range most likely to produce residual photoresistance. Avoid using the lithographic lens to illuminate under this energy range. Replace the anti-reflective coating of the microlens if necessary The above description is only the preferred embodiments of the present invention, and is not intended to limit the scope of patent application for the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall include Within the scope of the following patent applications.
第9頁 494473 圖式簡單說明 圖 式 簡 單 說 明 • 本 發 明 的 較佳實 施 例 將於往後之說 明 文字 中輔 以 下列 圖 形 做 更 詳 細 的闡述 圖 一 顯 示 光 罩 、微透 鏡 Λ 晶圓及投射光 與 雜散 光之 相 關關 係 示 意 圖 〇 圖 --- 顯 示 雜 散 光對接 觸 墊 (bonding pad) 、切割道上殘留 光 阻 影 響 的 情 況。 圖 --- 顯 示 依 據本發 明 的 方法，對每一 像 場施 以等 差 級數 之 昭 光 能 量 昭 射以得 知 被 檢驗之微透鏡 適 合用 的曝 光 能量 章巳 圍 〇 圖 號 對 昭 >、、、 表 ; 投 射 光 源 4 雜散 光 5 光 罩 10 透鏡 20 晶 圓 30 步進 平台 40 接 觸 墊 100 切割 道 110 殘 留 光 阻 120 像場 140、 1 4 0a、 140b、 140cPage 494473 Simple illustrations Simple illustrations • The preferred embodiment of the present invention will be explained in more detail in the following explanatory text with the following figures. Figure 1 shows the photomask, microlens, wafer and projection Schematic diagram of the correlation between light and stray light. Figure --- Shows the effect of stray light on the contact pad (bonding pad) and the residual photoresistance on the cutting track. Figure --- Shows according to the method of the present invention, each image field is applied to the image field of the same order of light energy to show the exposure energy of the tested microlens. ,,, table; projection light source 4 stray light 5 mask 10 lens 20 wafer 30 stepping platform 40 contact pad 100 cutting path 110 residual photoresistance 120 image field 140, 1 4 0a, 140b, 140c
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