TW552657B - Method for detecting wafer level defect - Google Patents

Abstract

A method for detecting wafer level defect by die-to-aerial image comparison is disclosed. The method utilizes patterns in a database which are used to form photo masks utilized in photolithography processes to simulate aerial images. The simulation aerial images are then compared with die images produced by the photo masks to find out wafer level defects without missing any repeating defect induced by the photo masks and mistaking any process deviation as a wafer level defect.

Description

552657 五、發明說明（1) 5-1發明領域： 本發明係關於一種偵測晶圓階段缺陷的方法，特別是 一種有關於藉由實際晶方影像與模擬影像比對（0丨64〇-A e r i a 1 I m a g e C 〇 m p a r i s ο η )來偵測晶圓階段缺陷的方法。 5 - 2發明背景： 晶圓階段缺陷檢測對於積體電路工業而言十分重要， 畢竟晶圓階段缺陷關係產品良率與製造成本。現形的晶圓 階段缺陷檢測方法包含晶方對晶方（Die-to_Die)檢測法 與晶方對貢料（Die-to-Database)檢測法。晶方對晶方檢 測法包含執行一已完成的光罩之自動影像檢測以找出光罩 上之缺陷，藉由比對存於影像檢測系統之光罩影像與以該 光罩進行製程而複製形成的圖案，來找出光罩上之缺陷。 檢測法與晶方對資料庫檢測法包含執行一已完成的光罩之 自動影像檢測以找出光罩上之缺陷，藉由比對存於影像檢 測系統之光罩影像與該光罩的設計資料庫内該光罩的設計 圖案，來找出祀罩上之缺陷。 晶方對晶方檢測法可提供一具有高敏感度的檢測結果 ，但卻會遺漏由光罩所造成之重複缺陷。相反地，晶方對 資料庫檢測法，可發現由光罩所造成之重複缺陷但缺乏敏 感度。此外晶方對資料庫檢測法常會出現錯誤的檢測結果552657 V. Description of the invention (1) 5-1 Field of the invention: The present invention relates to a method for detecting defects at the wafer stage, in particular to a method for comparing actual crystal images with simulated images (0 丨 64〇- A eria 1 I mage C 0mparis ο η) to detect defects at the wafer stage. 5-2 Background of the Invention: Wafer stage defect detection is very important for the integrated circuit industry. After all, wafer stage defects are related to product yield and manufacturing cost. Defective wafer stage defect inspection methods include the Die-to-Die inspection method and the Die-to-Database inspection method. The Cube-to-Cube inspection method includes performing an automatic image inspection of a completed photomask to find defects on the photomask, and comparing the photo of the photomask stored in the image detection system with the photomask to make a copy Pattern to find defects on the reticle. The inspection method and the crystal cube database inspection method include performing a completed automatic image inspection of the mask to find defects on the mask, and comparing the mask image stored in the image detection system with the design data of the mask The design pattern of the mask in the library to find the defects on the mask. The Cube-to-Cube inspection method can provide a highly sensitive inspection result, but it will miss repeated defects caused by the photomask. Conversely, the crystal inspection method of the database can find duplicate defects caused by the photomask but lack sensitivity. In addition, the crystal cube often has wrong detection results for the database detection method.

552657 五、發明說明（2) ，這是由於製程常出現非理想的狀況，即形成的圖案與理 想的圖案不完全相同以及，相位移光罩（Phase Shifting M a s k )與光學鄰近效應校正（Optical Proximity Effect Correction)才支袖i的使用。 近年來，相位移光罩（Phase Shifting fask)被發展 出來以改良微影製程。相位移光罩可增加影像對比與解析 度而不需降低波長或增加數值孔徑。對於一特定特徵尺寸 而言，相位移光罩可增加景深與製程容許範圍。 應用相位移微影製程時，係以光線的干涉來增加投射 至目標的影像深度與解析度。曝光光線於目標處的相位被 控制’以使相鄰亮區相位差達1 80度。暗區則位於相鄰亮 區間’並由光線的破壞性干涉產生，如此可增加投射至 標的影像深度與解析度。 9 § 另一中被發展來製造光罩以滿足包今外I p 4 & G 3彳政小尺寸特徵的 半導體元件製造的技術為光學鄰近效應校正（0pt i m552657 V. Description of the invention (2) This is because the process often has non-ideal conditions, that is, the pattern formed is not exactly the same as the ideal pattern, and the phase shift mask (Phase Shifting M ask) and optical proximity effect correction Proximity Effect Correction). In recent years, Phase Shifting Fasks have been developed to improve the lithography process. Phase shift masks can increase image contrast and resolution without reducing the wavelength or increasing the numerical aperture. For a specific feature size, a phase shift mask can increase depth of field and process tolerance. When applying the phase shift lithography process, the interference of light is used to increase the depth and resolution of the image projected onto the target. The phase of the exposure light at the target is controlled 'so that the phase difference between adjacent bright areas is 180 degrees. The dark area is located in the adjacent bright interval ’and is generated by the destructive interference of light, which can increase the depth and resolution of the image projected to the target. 9 § Another technology developed to manufacture photomasks to meet the needs of I p 4 & G 3 small size semiconductor device manufacturing technology for optical proximity effect correction (0pt i m

Proximity Effect C〇rrectlon)。光學鄰近效應4 由修正光罩佈局設計圖案，以使投射至目> A /、错 J 土曰私的影像解把 增加。由於現今微影製程設備的有限解析产，辦 二啊度 罩之圖案轉移至晶圓上之光阻層常產生一二％ = f光將光 題，稱為光學鄰近效應。以線寬控制為例，光學鄰7的問 產生例如圓角、臨限尺寸線性缺乏與续真p二n近效應 、、永長纟但短的現象。Proximity Effect Correcton). Optical proximity effect 4 The pattern is designed by correcting the layout of the mask, so that the image projected to the destination > A /, J J Tuyue private resolution is increased. Due to the limited analytical output of today's lithographic process equipment, the photoresist layer on the wafer when the pattern of the mask is transferred to the wafer often produces 12% = f light, which is called the optical proximity effect. Taking line width control as an example, the question of optical neighbor 7 produces phenomena such as rounded corners, lack of linearity of threshold dimensions, and near-p-n near-continuity effects.

第6頁 552657 五、發明說明（3) 此外光學鄰近效應也與後續之製程步驟問題結合，例 如光阻處理、乾蝕刻鄰近效應與濕蝕刻鄰近效應。為了要 達成足夠的線寬控制效果，光罩在設計時即針對光學鄰近 效應進行修正，外圍小耳朵（s e r i f )則被用來校正圓角而 圖案邊緣則被用來校正線寬誤差。 * 第一圖顯示一具有圓角之線圖案1 0 2、具有圓角、線 長縮短現象與一缺陷1 0 4之線圖案1 0 6之晶方影像。若缺陷 1 0 4是由光罩缺陷所造成，則缺陷1 0 4將會重複地出現於不 同晶方，而此時晶方對晶方檢測法將失效。第二圖顯示資 料庫中之光學鄰近效應校正圖案2 0 2與一線圖案2 0 4。製程 上產生的圓角、臨限尺寸線性缺乏與線長縮短的現象會被 晶方對資料庫檢測法誤認為光罩上的問題。若再加上相位 移光罩與光學鄰近效應校正技術的使用，資料庫會太過於 複雜使得晶方對資料庫檢測法更難以執行。因此非常有必 要提出一種新穎的偵測晶圓階段缺陷的方法，使得各種晶 圓階段缺陷能被偵測出來。這正是本發明提出的目的。 5 - 3發明目的及概述： 本發明之一目的為提供一種具高敏感度的偵測晶圓階 段缺陷的方法。Page 6 552657 V. Description of the invention (3) In addition, the optical proximity effect is also combined with the subsequent process steps, such as photoresist treatment, dry etching proximity effect and wet etching proximity effect. In order to achieve sufficient line width control effects, the reticle is designed to correct for optical proximity effects during design. The small peripheral ears (s e r i f) are used to correct rounded corners and the pattern edges are used to correct line width errors. * The first image shows a crystal image of a line pattern with rounded corners 102, a line pattern with rounded corners, shortened line length, and a defect of 104 line patterns. If the defect 104 is caused by a mask defect, the defect 104 will repeatedly appear in different crystal cubes, and the crystal-to-crystal inspection method will fail at this time. The second figure shows the optical proximity effect correction pattern 2 0 2 and the one-line pattern 2 0 4 in the database. The phenomenon of round corners, lack of critical dimension linearity, and shortened line lengths during the manufacturing process may be mistaken for problems on the photomask by the crystal pair detection method. If coupled with the use of phase shift reticle and optical proximity effect correction technology, the database would be too complicated, making it more difficult for the crystal cube to perform database detection. Therefore, it is necessary to propose a novel method for detecting wafer stage defects so that various wafer stage defects can be detected. This is the purpose proposed by the present invention. 5-3 Objects and Summary of the Invention: One object of the present invention is to provide a method for detecting wafer stage defects with high sensitivity.

552657 五、發明說明（4) 本發明之又一目的為提供一種適用於各種製程誤差的 債測晶圓階段缺陷的方法。 本發明之另一目的為提供一種能在相位移光罩與光學 鄰近效應校正技術應用時，仍能有效偵測晶圓階段缺陷的 方法。 · 為了達成上述之目的，本發明利用一種偵測晶圓階段 缺陷的方法，此方法包含下列步驟。首先提供一晶方影像 ，再利用一位於一資料庫之光罩圖案來產生一模擬影像， 該光罩圖案係用來製造一光罩，而該光罩係用於在一微影 製程中形成該晶方影像，然後再比較該晶方影像與該模擬 影像。 上述有關發明的簡單說明及以下的詳細說明僅為範例 並非限制。其他不脫離本發明之精神的等效改變或修飾均 應包含在的本發明的專利範圍之内。 5 - 4發明的詳細說明： 在此必須說明的是以下描述之製程步驟及結構並不包 含完整之製程。本發明可以藉各種積體電路製程技術來實 施，在此僅提及瞭解本發明所需之製程技術。552657 V. Description of the invention (4) Another object of the present invention is to provide a method for detecting defects at the wafer stage of a debt, which is applicable to various process errors. Another object of the present invention is to provide a method capable of effectively detecting defects at the wafer stage when the phase shift mask and the optical proximity effect correction technology are applied. In order to achieve the above object, the present invention utilizes a method for detecting defects at a wafer stage. The method includes the following steps. First, a crystal image is provided, and then a mask pattern located in a database is used to generate a simulated image. The mask pattern is used to manufacture a mask, and the mask is used to form a lithography process. The crystal image is then compared with the crystal image. The foregoing brief description of the invention and the following detailed description are examples only and are not limiting. Other equivalent changes or modifications that do not depart from the spirit of the invention should be included in the patent scope of the invention. 5-4 Detailed Description of the Invention: What must be explained here is that the process steps and structures described below do not include a complete process. The present invention can be implemented by various integrated circuit process technologies, and only the process technologies required to understand the present invention are mentioned here.

552657 五、發明說明（5) 〜〜_ 以下將根據本發明所附圖示 為簡單的形式且未依照比例$ =細的說明，請注意圖示均 瞭解本發明。 田^ ’而尺寸均被誇大以利於 為了要瞭解本發明，首 、“ 間（Process Window)。特^ 1需瞭解微影製程之製程空 持特徵之臨限尺寸（C r ; +寸疋特徵尺寸之製程空間為在維 v 11^ c a 1 η* . ，可容許之製程誤差或變動旦 1 mens 1 〇n)範圍的情形下 通常以可容許之焦距與曝光=:在微影製程中，製程空間 内特徵尺寸與臨限尺寸仍处j墨、交動來表不，在製程空間 圍内。 此、、隹持在原始設計尺寸可容許範 製程空間是從量測晶圓上經各種聚焦與曝光條件而形 成之臣品限尺寸而得，或是自Through-Focus Intensity Pr 〇 f i 1 e計算而得。在後者的計算方式中，曝光劑量係經 由改變量測臨限尺寸處之曝光強度而改變。而曝光強度的 曲線通常是由模擬或是由模擬影像量測系統（A e r i a 1 I ma g e M e a s u r e m e n t S y s t e m)的紀錄而得。模擬影像量測 系統係由具有數值孔徑之顯微鏡與照明條件以模擬微影曝 光狀況。模擬影像量測系統紀錄模擬以微影曝光系統透過 光罩曝光，將光罩上之圖案轉移至光阻所產生之模擬影像 (Aerial Image) 〇 本發明提供一種藉由實際晶方影像與模擬影像比對（552657 V. Description of the invention (5) ~~ _ The following description will be based on the drawings attached to the present invention in a simple form and not in accordance with the proportion $ = detailed description. Please note that the drawings are all familiar with the present invention. The dimensions are exaggerated to facilitate the understanding of the present invention. First, "Process Window". ^ 1 It is necessary to understand the critical dimensions (C r; + inch feature) of the vacant characteristics of the lithographic process. The process space of the size is within the range of dimension v 11 ^ ca 1 η *., The allowable process error or variation (1 mens 1 〇n), usually with the allowable focal length and exposure =: In the lithography process, The feature size and threshold size in the process space are still expressed in the ink and interaction, and are within the process space. This, and the original design size allows the standard process space to be measured from the wafer through various focus It is obtained from the limited size formed by the exposure conditions, or calculated from Through-Focus Intensity Pr 〇fi 1 e. In the latter calculation method, the exposure dose is changed by measuring the exposure intensity at the threshold size. And the exposure intensity curve is usually obtained by simulation or recorded by an analog image measurement system (Aeria 1 I ma ge M easurement System). The analog image measurement system is a microscope with a numerical aperture Illumination conditions to simulate the exposure of lithography. The simulation image measurement system records simulations to expose the lithography exposure system through a photomask and transfer the pattern on the photomask to an artificial image generated by a photoresist. The present invention provides a By comparing the actual crystal image with the simulated image (

第9頁 552657 五、發明說明（6) D i e - t 〇 - A e r i a 1 I m a g e C〇m p a r i s〇η)來偵測晶圓階段缺陷 的方法。如本案發明背景所述，晶方對晶方檢測法與晶方 對貢料庫檢測法均有其盲點。晶方對晶方檢測法不能發現 由光罩缺陷所引起之重複缺陷。相反地，晶方對資料庫檢 測法雖可發現由光罩缺陷所引起之重複缺陷，但卻會將製 程中出現非理想的狀況或製程誤差誤認為光罩缺陷。常見 的製程非理想狀況或製程誤差包含圓角（C ◦ r n e r R 〇 u n d i n g )、臨限尺寸線性缺乏（L a c k o f C r i ΐ i c a 1 D i m e n s i ο n Linearity)與線長縮短（Line End Shortening)的現象 特徵尺寸與曝光劑量及焦距具有函數關係。為了找出 晶方影像之缺陷，本發明利用資料庫中之圖案，藉由設定 微影製程參數例如焦距、波長與曝光劑量來產生模擬影像 。舉例來說，可利用第二圖中所示之圖案來產生光學鄰近 效應·校正（Optical Proximity Effect Correction)的模 擬影像，或利用相位移光罩模擬微影製程以產生一模擬晶 方影像。設定實際的曝光參數，可產生包含製程中非理想 的狀況或製程誤差的影像。由於資料庫中之光罩圖案為理 想狀況，晶方影像中由光罩缺陷所引起的重複缺陷將不會 出現在模擬晶方影像中。藉由比較實際晶方影像與模擬晶 方影像，可發現實際晶方影像中由光罩缺陷所引起的重複 缺陷。當使用相位移光罩與光學鄰近效應校正技術時，經 由設定微影製程參數，模擬晶方影像將會呈現出實際上使Page 9 552657 V. Description of the invention (6) D i e-t 〇-A e r i a 1 I m a g e C o m p a r i s〇η) to detect wafer stage defects. As described in the background of the present invention, the crystal-to-crystal method and the crystal-to-tribble store method both have their blind spots. The Cube-to-Cube inspection method cannot detect repetitive defects caused by mask defects. On the contrary, although Crystal's inspection method on the database can find duplicate defects caused by mask defects, it will mistake non-ideal conditions or process errors in the process as mask defects. Common process non-ideal conditions or process errors include rounded corners (C ◦ rner R 〇unding), threshold linearity lack (Lackof C ri ΐ ica 1 D imensi ο n Linearity), and line end shortening (Line End Shortening). Phenomenon feature size has a functional relationship with exposure dose and focal length. In order to find the defects of the crystal image, the present invention uses patterns in the database to generate simulated images by setting lithographic process parameters such as focal length, wavelength, and exposure dose. For example, the pattern shown in the second figure can be used to generate a simulated image of Optical Proximity Effect Correction, or a phase shift mask can be used to simulate the lithography process to generate a simulated crystal image. Setting actual exposure parameters can produce images that include non-ideal conditions or process errors in the process. Since the mask pattern in the database is ideal, repeated defects caused by mask defects in the crystal image will not appear in the simulated crystal image. By comparing the actual crystal image with the simulated crystal image, we can find the repetitive defects caused by the mask defects in the actual crystal image. When using phase shift mask and optical proximity effect correction technology, by setting the lithography process parameters, the simulated crystal image will show

第10頁 552657 五、發明說明（7) 用相位移光罩與光學鄰近效應校正技術時所產生的微影製 程結果。第三圖顯示線圖案模擬影像 3 0 2與3 0 4。線圖案 模擬影像 3 0 2與3 0 4顯示圓角現象，而線圖案模擬影像3 0 4 同時顯示線長縮短的現象。第一圖所示之重複缺陷1 0 4可 藉由比較第一圖所示之晶方影像與第三圖所示之模擬影像 而發現。此外線圖案1 0 2與1 0 6中的圓角現象與線圖案1 0 6 中的線長縮短現象不會被誤認為晶圓階段缺陷。藉由比較 晶方影像與模擬影像，同時出現在晶方影像與模擬影像的 製程中非理想狀況或製程誤差必然不會被視為晶圓階段缺 陷。 上述有關發明的詳細說明僅為範例並非限制。其他不 脫離本發明之精神的等效改變或修飾均應包含在的本發明 的專利範圍之内。Page 10 552657 V. Description of the invention (7) Lithography process results produced by using phase shift mask and optical proximity effect correction technology. The third image shows line pattern simulation images 3 0 2 and 3 0 4. The line pattern simulation images 3 0 2 and 3 0 4 show the phenomenon of rounded corners, while the line pattern simulation image 3 4 shows the phenomenon of shortened line length at the same time. The repeating defect 104 shown in the first picture can be found by comparing the crystal image shown in the first picture with the simulated picture shown in the third picture. In addition, the fillet phenomenon in the line patterns 102 and 106 and the line length shortening phenomenon in the line pattern 106 can not be mistaken for wafer stage defects. By comparing the crystal image and the simulation image, the non-ideal conditions or process errors that appear in the crystal image and the simulation image at the same time will not necessarily be considered as wafer-level defects. The above detailed description of the invention is merely an example and not a limitation. Other equivalent changes or modifications that do not depart from the spirit of the invention should be included in the patent scope of the invention.

552657 圖式簡单說明 為了能讓本發明上述之其他目的、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： 第一圖顯示一具有圓角之線圖案、具有圓角、線長縮 短現象與一缺陷之線圖案之晶方影像； 4 第二圖顯示資料庫中之光學鄰近效應校正圖案與一線 圖案；及 第三圖顯示線圖案模擬影像。 主要部分之代表符號： 1 0 2具有圓角之線圖案 1 0 4缺陷 1 〇 6具有圓角、線長縮短現象之線圖案 2 0 2光學鄰近效應校正圖案 2 0 4線圖案 3 0 2線圖案模擬影像 3 0 4線圖案模擬影像552657 Brief description of the drawings In order to make the other objects, features, and advantages of the present invention clearer and easier to understand, a preferred embodiment is described below in conjunction with the accompanying drawings to make a detailed description as follows: First diagram Display a crystal square image with rounded line patterns, rounded corners, shortened line length, and a defective line pattern; 4 The second image shows the optical proximity effect correction pattern and one line pattern in the database; and the third image A line pattern simulation image is displayed. Representative symbols of the main part: 1 0 2 line pattern with rounded corners 1 0 4 defect 1 〇 6 line pattern with rounded corners and shortened line length phenomenon 2 0 2 optical proximity effect correction pattern 2 0 4 line pattern 3 0 2 line Pattern simulation image 3 0 4 line pattern simulation image

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Claims (1)

552657 六、申請專利範圍 1. 一種偵測晶圓階段缺陷的方法，該偵測晶圓階段缺陷方 法包含下列步驟： 提供一晶方影像； 利用一位於一資料庫之光罩圖案來產生一模擬影像， 該光罩圖案係用來製造一光罩，而該光罩係用於在一微影 製程中形成該晶方影像；及 * 比較該晶方影像與該模擬影像。 2. 如申請專利範圍第1項所述之偵測晶圓階段缺陷的方法 ，其中上述之該模擬影像係經由設定微影製程參數包含焦 距、波長與曝光劑量來產生。 法影 方擬 的模 陷正 缺校 段應 階效 圓近 晶鄰 測學 偵光 之一 述含 所包 項像 T—一影 第擬 圍模 範該 利之 專述 請上 中 如其 方 的 陷 缺 段 階。 圓罩 晶光 測移 偵位 之相 述一 所含 項包 1 罩 第光 圍該 範之 專上 請中 申其 如， 4法 方 陷 缺 段 階 圓 晶 測 偵 該 法 方 的 陷 缺 段 階： 圓驟 晶步 測列 偵下 種含 一 包 5法 效光 近該 鄰而 學 ， 光罩 一光 生一 產造 來製 案來 圖用 罩係 光案 之圖 庫罩 ;料光 像資該 影一， 方於像 晶位影 一 一擬 供用模 提利正 校 應552657 6. Scope of Patent Application 1. A method for detecting defects at the wafer stage, the method for detecting defects at the wafer stage includes the following steps: providing a crystal image; using a mask pattern located in a database to generate a simulation Image, the mask pattern is used to make a mask, and the mask is used to form the crystal image in a lithography process; and * compare the crystal image with the simulated image. 2. The method for detecting wafer-level defects as described in item 1 of the scope of patent application, wherein the above-mentioned simulation image is generated by setting a lithography process parameter including a focal length, a wavelength, and an exposure dose. The shadowing of the missing section proposed by the French shadow party should be a step effect. One of the near-neighbor detection and light detection circles contains the included item image T-Yingying. The model of the surrounding model should be described in detail. Please go to the middle of the missing section. The description of the round cover crystal light movement detection position contains an included item package 1 cover Di Guangwei the post-secondary of the fan, please Zhong Zhongqiru, 4 method of the trapped segment of the circle method of the method to detect the trapped segment of the method: The crystal step test series contains a pack of 5 method light effects to learn near the neighbor, a photomask made by light and production to make a case to map the photo mask using the mask system; material photo materials should be a shadow, Fang Yu Xiangjing Ying Ying planned to use the model for correction 第13頁 552657 六、申請專利範圍 罩係用於在一微影製程中形成該晶方影像；及 比較該晶方影像與該光學鄰近效應校正模擬影像。 6. 如申請專利範圍第5項所述之偵測晶圓階段缺陷的方 法，其中上述之該光學鄰近效應校正模擬影像係經由設定 微影製程參數包含焦距、波長與曝光劑量來產生。 7. —種偵測晶圓階段缺陷的方法，該偵測晶圓階段缺陷方 法包含下列步驟： 提供一晶方影像； 利用一位於一資料庫之光罩圖案來產生一模擬影像， 該光罩圖案係用來製造一相位移光罩，而該相位移光罩係 用於在一微影製程中形成該晶方影像；及 比較該晶方影像與該模擬影像。Page 13 552657 6. Scope of patent application The mask is used to form the crystal image in a lithography process; and compare the crystal image with the optical proximity effect correction simulation image. 6. The method for detecting wafer-level defects as described in item 5 of the scope of patent application, wherein the optical proximity effect correction simulation image is generated by setting a lithography process parameter including a focal length, a wavelength, and an exposure dose. 7. A method for detecting wafer-level defects, the method for detecting wafer-level defects includes the following steps: providing a crystal cube image; using a mask pattern located in a database to generate a simulated image, the mask The pattern is used to manufacture a phase shift mask, and the phase shift mask is used to form the crystal image in a lithography process; and the crystal image and the simulated image are compared. 第14頁Page 14