3498twf.doc/005 3498twf.doc/005 經濟部中央標準局貝工消費合作社印製 A7 B7 五、發明説明（I ) 本發明是有關於一種在微影（Photolithography)製程中 可以修正光學近距效應（Optical Proximity Effect, ΟΡΕ)的位 元線圖案，且特別是有關於一種適用於動態隨機存取記憶 體（Dynamic Random Access Memory, DRAM)元件中減少光 學近距效應的位元線圖案。 當動態隨機存取記憶體的積集度不斷增加，記憶元件 (Memory Cell)之間的間隔距離隨之減小，因此增加了微影 的困難度，同時也提高了電路設計的挑戰性。在微影製程 中，首先在一晶圓（Wafer)表面覆蓋一光阻層(Photoresist)， 然後使用具有定義圖案之光罩（Photomask)爲網線罩幕 (Reticle)。來自光源的平行光，經過此一網線罩幕之後，使 晶圓表面光阻層曝光（Exposure)，再經過顯影 (Development)，將網線罩幕上的圖案轉移至光阻層以完成 微影步驟。 網線罩幕是微影設備中不可或缺的元件。在網線罩幕 上具有積體電路元件單層之線路設計圖案。典型的網線罩 幕是由平坦且透明的石英玻璃板所構成，半導體元件各層 的圖案，則是在玻璃的表面覆蓋一層遮光物質（Light-Blocking Matenal)來製作，其中遮光物質的材質包括鉻。網 線罩幕是置於微影設備的光源與聚集鏡片（Focusing Lens) 之間，此光源所產生的是具有某一特定波長範圍之光波’ 聚集鏡片則是步進機（Stepper)的元件之一。進行微影步驟 時，將表面覆有光阻層之晶圓置於步進機的下方’特定波 4 本紙張尺度適用中國國家橾準（CNS ) A4规格（210X297公釐） (請先閱讀背面之注意事項算填寫本頁) 装. 订 349Stwf.doc/005 349Stwf.doc/005 經濟部中央標準局員工消费合作社印袋 A7 B7 五、發明説明（>) 長範圍之光波經由光源產生之後照在網線罩幕上，光波會 通過未覆蓋鉻膜部份的石英玻璃，再投射在晶圓表面的光 阻層上，將網線罩幕上之線路圖案完整轉移至光阻層。 當光源所產生的光波波長大於網線罩幕線路圖案上特 徵尺寸(Feature Sizes)的大小，光波在通過網線罩幕時，會 受到罩幕上鉻膜之影響，產生折射（Refract)及散射 (Scatter)。由於折射及散射的干擾，使得轉移至光阻層的圖 案出現轉角圓弧化（Rounding)或光學相差（Optical Distortion)的現象。在罩幕上線路圖案之特徵尺寸較大的情 況下，例如線路圖案的關鍵尺寸(Critical Dimensions)大於 Ιμπι時，散射及折射的影響較小。不過當罩幕上線路圖案 的特徵尺寸小於Ιμπι時，散射及折射的影響就非常嚴重。 尤其是在線路圖案之特徵尺寸與微影製程所使用的光波波 長相近時，散射及折射造成圓弧化及相差的現象十分明 顯。這種由折射、繞射(Diffraction)及散射造成相差的現象， 稱爲光學近距效應（ΟΡΕ)。此種在進行位元線或內連線等線 路圖案轉移時產生的誤差，會導致轉移後的圖案解析度變 差，造成關鍵尺寸偏差，因而使得良率下降’積體電路成 品的效能變差，甚至完全無法使用。 爲解決光學近距效應所造成的影響’因而發展出許多 不同的方法，藉以對光學近距效應進行修正。例如光學近 距效應校正（Optical Proximity Correction, OPC)是在設目十網 線罩幕線路圖案時，在原始圖案的特定位置加上遮光區’ 5 本紙張尺度適用中國國家標準（CNS > A4規格（210X297公嫠） I ^ I 裝 訂 (請先閲讀背面之注意事項再填寫本頁) 3498twf.doc/005 3498twf.doc/005 經濟部中央標準局員工消费合作社印製 A7 B7 五、發明説明（令） 以克服由繞射及散射所造成的相差效應。另一種減少光學 近距效應的方法是使用相移式光罩(Phase Shifting Mask)進 行微影步驟。此外也可以採用變形式照明（Deformation Illumination)，例如傾斜式照明（Oblique Illumination)，改變 照射光源入射角度，以提升圖案解析度，減少光學近距效 應。 雖然上述這些習知方法都可以改善光學近距效應的影 響，例如使用相移式光罩控制曝光時的光波相位；而使用 變形式照明則是控制曝光時的光波繞射階級（Order of Diffraction)，藉以減少圖案轉移產生的偏差。但在實際應 用時，這些習知方法對於光學近距效應仍然難以進行必需 的修正。 在動態隨機存取記憶體製程中，製作線路圖案層之內 連線的罩幕，及蝕刻形成這些內連線，是必需的步驟。這 些內連線包括位兀線。請參照第1圖，其所繪示的是一種 習知用於蝕刻形成動態隨機存取記憶體中位元線的光罩圖 案。其中位元線光罩圖案101中的介層墊(Vm Pads)是在等 間距平行排列的複數條內連線1〇3之間。當這些做爲位元 線之平行內連線的間隔縮小時，光學近距效應會使得位元 線圖案在圖案轉移時產生相差。 請參照第1圖，位元線光罩圖案1〇1是在微影設備中 網線罩幕上的理想設計圖案’其中微影設備包括步進機。 在位元線光罩圖案101中包括複數條互相平行的位元線 6 本紙張尺度適用中國國家標準（CNS ) A4規格（21〇><297公羡） ----^------^------、1T------j (請先閱讀背面之注意事項再填寫本頁) 3498twf.doc/005 A7 ____B7 五、發明説明（V·) 103，這些平行的位元線排列成欄狀陣列(c〇lumnar AiTay)。 在每一條位兀線103上，具有複數個間隔相等的接觸墊 1〇5。這些接觸墊105是由在內層介電材料層（InteHayer3498twf.doc / 005 3498twf.doc / 005 A7 B7 printed by the Shellfish Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (I) The present invention relates to a method that can correct the optical close-up effect in the photolithography process (Optical Proximity Effect, ΟΡΕ) bit line pattern, and in particular, it relates to a bit line pattern suitable for reducing optical proximity effect in a dynamic random access memory (DRAM) device. When the accumulation of dynamic random access memory continues to increase, the separation distance between memory cells decreases accordingly, which increases the difficulty of lithography and also increases the challenge of circuit design. In the lithography process, a wafer (Wafer) surface is first covered with a photoresist, and then a photomask with a defined pattern is used as a network mask (Reticle). After the parallel light from the light source passes through the screen mask, the wafer surface photoresist layer is exposed (Exposure), and after development, the pattern on the screen mask is transferred to the photoresist layer to complete the lithography step. Network cable screen is an indispensable element in lithographic equipment. There is a single-layer circuit design pattern of integrated circuit components on the network cable cover. A typical network cable cover is composed of a flat and transparent quartz glass plate. The pattern of each layer of the semiconductor element is made by covering a layer of light-blocking matenal on the surface of the glass. The material of the light-blocking substance includes chromium. . The cable shield is placed between the light source of the lithographic equipment and the focusing lenses. This light source generates light waves with a specific wavelength range. The focusing lens is a component of a stepper. One. When performing the lithography step, place the wafer with the photoresist layer on the bottom of the stepper. 'Specified wave 4 This paper size applies to China National Standard (CNS) A4 specification (210X297 mm) (Please read the back first (Notes for filling in this page) Fill in. Order 349Stwf.doc / 005 349Stwf.doc / 005 Printed bags A7 B7 of the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (>) Long-range light waves On the screen of the network cable, the light waves will pass through the quartz glass that is not covered by the chrome film, and then be projected on the photoresist layer on the wafer surface to completely transfer the line pattern on the screen of the network cable to the photoresist layer. When the wavelength of the light wave generated by the light source is larger than the Feature Sizes on the line pattern of the network cable screen, the light wave will be affected by the chromium film on the screen screen when it passes through the network cable screen, causing refract and scattering. (Scatter). Due to the interference of refraction and scattering, the pattern transferred to the photoresist layer has the phenomenon of corner rounding or optical distortion. In the case where the characteristic size of the line pattern on the cover is large, for example, when the critical dimensions of the line pattern are larger than 1 μm, the influence of scattering and refraction is small. However, when the characteristic size of the line pattern on the mask is less than 1 μm, the effects of scattering and refraction are very serious. Especially when the characteristic size of the line pattern is close to the wavelength of the light wave used in the lithography process, the phenomenon of arcing and phase difference caused by scattering and refraction is very obvious. This kind of phase difference caused by refraction, diffraction (diffraction) and scattering is called optical close-range effect (OPE). Such errors in the transfer of line patterns such as bit lines or interconnects will lead to poor pattern resolution after the transfer, resulting in critical dimension deviations, which will reduce yield. , Or even completely unusable. To address the effects of the optical close-up effect ', many different methods have been developed to correct the optical close-up effect. For example, Optical Proximity Correction (OPC) is to add a light-shielding area at a specific position of the original pattern when setting up the screen pattern of the Ten Mesh Cable Screen. 5 This paper size applies the Chinese National Standard (CNS > A4 Specifications (210X297 cm) I ^ I Binding (please read the precautions on the back before filling this page) 3498twf.doc / 005 3498twf.doc / 005 Printed by the Consumer Standards Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention ( Order) to overcome the phase difference effect caused by diffraction and scattering. Another method to reduce the optical close-up effect is to use a phase shifting mask (Phase Shifting Mask) for the lithography step. In addition, it is also possible to use variable illumination Illumination), such as oblique illumination (Oblique Illumination), change the incident angle of the illumination source to improve the pattern resolution and reduce the optical close-up effect. Although these conventional methods can improve the effect of optical close-up effect, such as using phase shift Type photomask controls the phase of light waves during exposure; the use of variable illumination controls the light wave diffraction stages during exposure Order of Diffraction), in order to reduce the deviation caused by pattern transfer. However, in practical applications, these conventional methods are still difficult to correct the optical proximity effect. In the dynamic random access memory system process, the circuit pattern layer is made. The mask of the interconnects and etching to form these interconnects are necessary steps. These interconnects include bit lines. Please refer to Figure 1, which shows a conventional method for etching to form dynamic random Access the mask patterns of bit lines in the memory. The via pads (Vm Pads) in the bit line mask pattern 101 are between a plurality of inner lines 10 parallel arranged at equal intervals. When these As the distance between the parallel interconnects of the bit lines is reduced, the optical close-up effect will cause the bit line patterns to differ when the pattern is transferred. Please refer to Figure 1, the bit line mask pattern 10 is in the micro The ideal design pattern on the screen of the network cable in the shadow equipment 'Where the lithography equipment includes a stepper. The bit line mask pattern 101 includes a plurality of parallel bit lines. 6 This paper size applies to Chinese national standards (CNS ) A4 (21〇 > < 297 public envy) ---- ^ ------ ^ ------, 1T ------ j (Please read the precautions on the back before filling in this Page) 3498twf.doc / 005 A7 ____B7 V. Description of the Invention (V ·) 103. These parallel bit lines are arranged in a columnar array (columnar AiTay). On each bit line 103, there are a plurality of spaces. Equal contact pad 105. These contact pads 105 are made of an inner dielectric material layer (InteHayer
Dielectric Layer)中的導電接觸層(Conductive Contacts)所形 成的。此一導電接觸層是用以電性連接在其下方的電容器 記憶兀件。此外，每間隔一條位元線103的兩條位元線1〇3 上之複數個接觸墊105彼此在垂直位元線的方向對齊，形 成一棋盤狀圖案。 當動態隨機存取記憶體的積集度增加時，第〗圖中位 元線103之間的距離與接觸墊1〇5之間的距離會隨之縮 減。因而將第1圖中的理想位元線光罩圖案101轉移至晶 圓表面光阻層時’由於光學近距效應使得轉移之圖案產生 嚴重偏差。 經濟部中央標準局員工消費合作社印製 I u i nn 1 ----- *R --1 n^i 1^1 m (請先聞讀背面之注意事項再填寫本頁) 接者請參照第2圖，其所繪示的是受光學近距效應影 響轉移至晶圓表面光阻層的位元線光罩圖案。比較第】圖 與第2圖可知’第1圖中接觸墊105具有垂直的轉角，在 光罩圖案轉移至晶圓表面光阻層上時，由於光學近距效應 的緣故’線形圖案的側邊部分會變得較原圖形膨脹 (Bulged) ’垂直的轉角會形成平滑的圓弧形（R〇unded)轉 角，使得第2圖中的接觸墊205具有圓弧外形。當接觸墊 205因光學近距效產生圖形膨脹，而與相鄰位元線產生連接 時’即造成架橋效應(Bridging Effect)。此一架橋效應若不 加以修正’則會導致在後續製程產生電性短路，因而降低 7 本紙張尺度逋用中國國家樣準（CNS > A4規格（210X297公釐） 3498twf.doc/005 A7 ____B7_ 五、發明説明（Γ) 產品的良率。 一般而言，架橋效應是肇因於使用如第1圖中具有明 確轉角或邊緣之光罩圖案進行曝光時產生繞射的結果。在 微影製程中，步進機上的鏡片都具有光圈。但此一鏡片並 無法聚集較高階的繞射光（Higher Order Diffraction)，所以 在成像時會漏失入射光中筒頻項（High Frequency Harmonics)，出現架橋效應轉角圓弧化的特徵。 因此本發明的主要目的就是在提供一種校正光學近距 效應的位元線圖案，特別是一種用於動態隨機存取記憶體 製程中，製作位元線所使用的光罩圖案。 經濟部中央標準局員工消費合作社印繁 (請先閱讀背面之注意事項再填寫本頁) 基於本發明之上述目的，提出一種在半導體記憶元件 製程中使用之位元線光罩圖案。此一位元線光罩圖案包括 複數條位元線，這些位元線彼此平行形成欄狀陣列，每一 條位元線上具有複數個間隔相等的接觸墊(Contact Pads)， 而且在間隔一條位元線的兩條位元線上之接觸墊彼此在垂 直位元線的方向排列對齊。這些位元線上接觸墊具有矩形 外觀’但在接觸墊矩形的四個直角轉角，分別移除一較小 的矩形部份，此外在接觸墊平行於位元線的兩個側邊，亦 分別移除一較小的矩形部份。 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： 8 本紙張尺度適用中國國準（CNS ) A4规格（210乂297公|^ ~~ 3498twf.doc/005 3498twf.doc/005 經濟部中央標準局員工消費合作社印製 A7 B7 五、發明説明（厶） 第1圖繪示一種習知用於動態隨機存取記憶體製程的 位元線光罩圖案。 第2圖繪示一種使用習知位元線光罩圖案產生光學近 距效應的圖案。 第3圖繪示依照本發明一較佳實施例，一種用於動態 隨機存取記憶體製程的位元線光罩圖案。 第4圖繪示依照本發明一較佳實施例，一種用於動態 隨機存取記憶體製程位元線光罩圖案的接觸墊圖案。 圖式之標記說明： 101、201、301 :位元線光罩圖案 103、203、303 :位元線 105、205、305 :接觸墊 3〇7 :接觸墊直角轉角移除區域 309 :接觸墊側邊移除區域 a:正方形接觸墊之邊長 b:正方形直角轉角移除區域之寬度 實施例 請參照第3圖，其所繪示的是依照本發明一較佳實施 例，一種用於動態隨機存取記憶體製程的位元線光罩圖 案。位元線光罩圖案301如圖所示，其中位元線303的整 體排列方式與第1圖中習知位元線光罩圖案1〇1相同。在 位元線光罩圖案301中包括複數條互相平行的位元線 303，這些平行的位元線303排列成欄狀陣列。在每一條位 9 本紙張尺度適用中國國家標準（CNS ) A4規格（210Χ297公釐） I ^ 裝 訂 (請先閱讀背面之注意事項再填寫本頁) 3498twf. doc/005 3498twf. doc/005 經濟部中央標準局員工消費合作社印裝 A7 B7 五、發明説明（// ) 元線303上，具有複數個間隔相等的接觸墊305。每間隔一 條位元線303的兩條位元線303上之複數個接觸墊305彼 此在垂直位元線的方向對齊，形成一棋盤狀圖案。 本實施例與習知不同之處在於位元線光罩圖案中接觸 墊305的外觀形狀。在習知中接觸墊105的形狀爲一矩形， 而本發明中之接觸墊305的圖案形狀則是一矩形移除部分 面積的圖案。 其次請參照第4圖，其所繪示的是依照本發明一較佳 實施例，一種用於動態隨機存取記憶體製程位元線光罩圖 案的接觸墊圖案。於形狀爲矩形的接觸墊305上，在其直 角轉角處移除一較小之矩形區域307。其中接觸墊305較佳 的形狀爲一正方形，此正方形接觸墊305之邊長以”a”表 示。在接觸墊305直角轉角處移除之矩形區域307，其較佳 的形狀亦爲一正方形。此正方形移除區域307之邊長則是 以”b”表示。其中直角轉角移除區域307之邊長”b”的長度約 爲接觸墊305邊長”a”的百分之十至百分之二十，”b”的較佳 値爲” a”的七分之一。 此外在接觸墊305上平行於位元線而不與位元線相接 的兩個側邊中央部份，亦分別移除一較小的矩形區域309。 此一側邊移除區域309之較佳形狀亦爲一正方形，其邊長 與直角轉角移除區域307的邊長”b”相同。 移除前述直角轉角及側邊正方形區域之後，此一修正 後的接觸墊圖案可以明顯改善光學近距效應所造成的圖案 ----一------' -裝------訂------ (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（2丨〇X297公嫠） 3498twf.doo/005 A7 B7 五、發明説明（S ) 偏差。 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。 (請先閲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標準（CNS ) A4規格（210X297公釐）Dielectric Layer) is formed by conductive contacts. This conductive contact layer is used to electrically connect the capacitor memory element underneath it. In addition, each of the plurality of contact pads 105 on two bit lines 103 separated by one bit line 103 is aligned with each other in the direction of the vertical bit line to form a checkerboard pattern. When the accumulation degree of the dynamic random access memory is increased, the distance between the bit lines 103 in the first figure and the distance between the contact pads 105 will decrease accordingly. Therefore, when the ideal bit line reticle pattern 101 in FIG. 1 is transferred to the photoresist layer on the surface of the wafer, the transferred pattern has a serious deviation due to the optical proximity effect. Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs I ui nn 1 ----- * R --1 n ^ i 1 ^ 1 m (Please read the precautions on the back before filling out this page) Figure 2 shows the bit line mask pattern transferred to the photoresist layer on the wafer surface due to the optical proximity effect. Comparing Figure 1 with Figure 2, you can see that the contact pad 105 in Figure 1 has a vertical corner. When the mask pattern is transferred to the photoresist layer on the wafer surface, the side portion of the linear pattern is due to the optical proximity effect It will become more bulged than the original pattern. The vertical corners will form smooth rounded corners, so that the contact pad 205 in FIG. 2 has an arc shape. When the contact pad 205 generates a pattern expansion due to the optical proximity effect and is connected to an adjacent bit line, it causes a bridging effect. If this bridge effect is left uncorrected, it will cause electrical short-circuits in subsequent processes, which will reduce 7 paper sizes and use Chinese national standards (CNS > A4 size (210X297 mm) 3498twf.doc / 005 A7 ____B7_ 5. Description of the invention (Γ) The yield of the product. In general, the bridging effect is the result of diffraction caused when a mask pattern with clear corners or edges is used for exposure as shown in Figure 1. In the lithography process The lens on the stepper has an aperture. However, this lens cannot collect higher order diffracted light (Higher Order Diffraction), so the high frequency harmonics of the incident light will be missed during imaging, and a bridge will appear. The corner of the effect is rounded. Therefore, the main object of the present invention is to provide a bit line pattern for correcting the optical proximity effect, especially a bit line used in the dynamic random access memory system to make a bit line. Photomask pattern. Consumer Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs of India (please read the precautions on the back before filling this page) Based on the above purpose of the present invention, A bit line mask pattern used in the manufacturing process of a semiconductor memory element is proposed. The bit line mask pattern includes a plurality of bit lines, and the bit lines are parallel to each other to form a columnar array, and each bit line has a complex number Contact pads are equally spaced, and the contact pads on the two bit lines spaced one bit line are aligned with each other in the direction of the vertical bit line. The contact pads on these bit lines have a rectangular appearance 'but The four right-angled corners of the contact pad rectangle respectively remove a smaller rectangular portion, and in addition, on the two sides of the contact pad parallel to the bit line, a smaller rectangular portion is also removed. The above and other objects, features, and advantages of the invention can be more clearly understood. The following is a detailed description of a preferred embodiment in conjunction with the accompanying drawings as follows: Brief description of the drawings: 8 This paper scale applies to China National Standard (CNS) A4 Specification (210 乂 297) | ^ ~~ 3498twf.doc / 005 3498twf.doc / 005 Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs A7 B7 V. Description of Invention (厶) Figure 1 shows A conventional bit line mask pattern used in a dynamic random access memory system. FIG. 2 shows a pattern using the conventional bit line mask pattern to generate an optical close-up effect. FIG. 3 shows a pattern according to the present invention. A preferred embodiment of the present invention is a bit line mask pattern for a dynamic random access memory system. FIG. 4 illustrates a dynamic random access memory system bit according to a preferred embodiment of the present invention. Contact pad pattern of element line reticle pattern. Symbol description of the figure: 101, 201, 301: bit line mask pattern 103, 203, 303: bit line 105, 205, 305: contact pad 307: contact Pad right-angle corner removal area 309: contact pad side removal area a: side length of square contact pad b: width of square right-angle corner removal area For an example, please refer to FIG. 3, which is shown in accordance with the present invention A preferred embodiment is a bit line mask pattern for a dynamic random access memory system. The bit line mask pattern 301 is shown in the figure. The overall arrangement of the bit line 303 is the same as the conventional bit line mask pattern 101 in the first figure. The bit line mask pattern 301 includes a plurality of parallel bit lines 303, and the parallel bit lines 303 are arranged in a columnar array. 9 paper sizes in each row apply Chinese National Standard (CNS) A4 specifications (210 × 297 mm) I ^ Binding (please read the precautions on the back before filling this page) 3498twf. Doc / 005 3498twf. Doc / 005 Ministry of Economy Printed by A7 B7 of the Consumer Standards Cooperative of the Central Bureau of Standards 5. Description of Invention (//) On the line 303, there are a plurality of contact pads 305 with equal intervals. The plurality of contact pads 305 on the two bit lines 303 spaced apart by one bit line 303 are aligned with each other in the direction of the vertical bit lines to form a checkerboard pattern. This embodiment is different from the conventional one in the appearance shape of the contact pad 305 in the bit line mask pattern. In the prior art, the shape of the contact pad 105 is a rectangle, and the shape of the pattern of the contact pad 305 in the present invention is a pattern with a rectangular area removed. Next, please refer to FIG. 4, which illustrates a contact pad pattern for a dynamic line access mask pattern of a dynamic random access memory system according to a preferred embodiment of the present invention. On the contact pad 305 having a rectangular shape, a smaller rectangular area 307 is removed at a right corner thereof. The preferred shape of the contact pad 305 is a square. The side length of the square contact pad 305 is indicated by "a". The rectangular area 307 removed at the right corner of the contact pad 305 is also preferably a square. The side length of the square removal area 307 is indicated by "b". The length of the side length “b” of the right-angle corner removal area 307 is about 10% to 20% of the side length “a” of the contact pad 305, and the preferred “b” is seven times that of “a” One-third. In addition, a small rectangular area 309 is also removed from the central portions of the two sides of the contact pad 305 that are parallel to the bit line and do not contact the bit line. The preferred shape of this side edge removal area 309 is also a square, and its side length is the same as the side length "b" of the right angle corner removal area 307. After removing the aforementioned right-angled corners and the square area on the side, this modified contact pad pattern can significantly improve the pattern caused by the optical close-up effect ---- 一 ------ '-装 ----- -Order ------ (Please read the precautions on the back before filling this page) This paper size applies to Chinese National Standard (CNS) A4 specification (2 丨 〇297297) 3498twf.doo / 005 A7 B7 V. DESCRIPTION OF THE INVENTION (S) Deviation. 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. (Please read the notes on the back before filling out this page) Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs This paper is sized for China National Standard (CNS) A4 (210X297 mm)