1222099 A7 B7 五、發明說明（,） 相關申請之交互參照 本申請案主張2001年5月25日申請之暫時申請序列 號60/293,754之專利的利益，在此以合倂其整體作爲參考。 本發明領域 本發明係有關於半導體晶圓與其他工件之離子植入系 統以及方法，並且更特別地係有關於利用具有可變空間頻 率之掃描線來控制劑量精確度以及劑量均勻性之離子植入 系統及方法。 本發明背景 離子植入是一種用來將可以改變導電性的雜質引入到 半導體晶圓中的標準技術，一種欲求之雜質材料在離子源 中離子化’加速這些離子以形成具有特定能量的離子束， 然後此離子束被導入晶圓的表面。離子束中具有能量的離 子穿透入半導體材料塊，並且嵌入到半導體材料中的晶格 裡’以形成具有欲求導電性的區域。 離子植入系統通常包括一個用來將氣體或是固體材料 轉換爲定義明確的離子束的離子源。該離子束經由質量分 析以除去不希望有的離子種類，然後被加速到一個希望的 能量並且被導引到靶材平面。大多數的離子植入機使用在 長度和寬度上都遠小於晶圓的離子束，並且透過離子束之 電子式掃描，將劑量分配到整個晶圓，其係以機械地移動 晶圓的方式或是透過離子束掃描以及鬲圓移動的結合來達 3 患紙張尺度適用中國國家標準（CNS)A4規格（21〇 x 297公釐） (請先閱讀背面之注意事項再填寫本頁) 訂------ Φ 1222099 A7 _____B7 五、發明說明（〆） 成。使用電子式離子束掃描以及晶圓機械運動結合的離子 植入機在Berrian等人在1990年5月1曰公佈的美國專利 案號第4，922，106號以及在Berrian等人在1990年I2 月25日公佈的美國專利案號第4，980，562號中揭露。這 些專利描述了在這種系統中控制掃描以及劑量的技術。 離子植入機中掃描以及劑量控制系統的重要目標是獲 得劑量精確度以及劑量均勻性。亦即，離子植入機被要求 植入達成一特定劑量的摻雜原子到晶圓之中，以及完成橫 跨晶圓表面的一特定的劑量均勻性。爲了達到劑量均勻性 以及劑量精確度，先前習知技術中之離子植入機利用可變 的電子式掃描速度以及幾乎恒定的機械傳輸速度，以使得 掃描線在晶圓的表面上一致地分配。晶圓的完整植入涉及 幾種完全的晶圓轉寫(pass over)，直到達到希求的總劑量 。介於掃描線之間的間距典型地比在機械傳輸方向中之離 子束高度要小，以確保掃描線的重疊並達到劑量的均勻性 〇 如同上述所指出的，典型的植入實驗規劃可能涉及多 重的完整晶圓轉寫。離子束在法拉第杯上進行電子式掃描 子，該法拉第杯在植入期間每隔一段時間量測離子束電流 。劑量測量用來產生被植入之晶圓的劑量映射。因爲劑量 映射是基於測到的離子束電流，離子束電流的變化被列人 考慮。劑量映射係由劑量控制系統將其與一個特定的劑量 映射比較的方式評估。在一些實際劑量比特定的劑量少的 區域之中進行劑量之校正掃描。 4 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁) 訂------ 1222099 A7 __.__B7___ 五、發明說明（）） (請先閱讀背面之注意事項再填寫本頁) 然而，在某些條件下，劑量校正在習知技術中之劑量 控制演算法之中是無法使用的。尤其是，掃描系統會被能 夠施加於晶圓的最小劑量校正所特徵化。最小校正由以下 步驟所產生，在特定的植入期間離子束電流實質上是固定 的，並且基於掃描放大器的特性，電子式掃描速度具有一 個最大値。因此，能夠施加於晶圓的劑量校正具有一個較 低的下限。如果需求的劑量校正比最小校正少，這個希求 的劑量無法以先前習知的掃描技術來達成。如果在這種情 況下把最小校正施加於晶圓上，實際劑量將超過希求的劑 量。如果最小校正沒有施加在這個晶片上，實際劑量將保 持比希求的劑量要小。 依此，需要改良的離子植入方法以及設備。 本發明之槪要 本發明使用一種與灕子植入機相關的方式來描述，其 中該離子束在一方向上進行電子掃描，通常以水平的方向 ，而且該晶圓或是其他的工件在第二方向上機械地傳動， 一般在垂直的方向，以在晶圓表面上分佈此離子束。離子 束的電子掃描產生掃描線，而晶圓的機械傳動將掃描線分 配到晶圓的表面上。控制晶圓上掃描線的空間頻率以控制 劑量以及劑量的均勻性。 根據本發明的第一個方面，提供一種工件的離子植入 方法。該方法包括產生一個離子束，將離子束在第一方向 上橫跨工件掃描以產生掃描線，以及在與離子束相關的第 5 七紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 1222099 A7 ___._B7 _ 五、發明說明（今） 二方向傳動這個工件，以將掃描線分配在工件上，並且依 據一個希求的劑量映射來控制工件上掃描線的空間頻率。 根據本發明的另一個觀點，提供一種用以工件離子植 入的方法。該方法包括產生一個離子束，將離子束在第一 方向上橫跨工件掃描以產生掃描線，在相對於離子束的第 二方向傳動這個工件，於是掃描線可以一標準空間頻率分 布在工件上，取得一個工件的劑量映射，然後如果取得的 劑量映射不在規格之中而且所需要的劑量校正與以掃描線 的標準空間頻率所能獲得的最小劑量校正還要小的話，啓 動一個劑量校正植入並且在劑量校正植入的整個期間控制 掃描線的空間頻率。 控制掃描線空間頻率的步驟可以包含(a)選定一組具有 標準空間頻率的η條掃描線，其中n表示這組掃描線的數 目，（b)決定是否最小劑量校正除以數値η的數字是小於或 是等於必須的劑量校正，（c)如果最小劑量校正除以數値η 的數字是小於或是等於必須的劑量校正的話，在選定的掃 描線群組中啓動離子束的掃描，然後(d)如果最小劑量校正 除以數値η的數字不小於或是等於必須的劑量校正，而且 在選定的掃描線群組中的掃描線數量η小於一個最大値的 話’將這組掃描線中掃描線的數量η增加並且重覆步驟 (b)-(d)。當選定的掃描線群組中的掃描線數量η等於該最 大値時，而且當最小劑量校正除以數値η的數字不小於或 是等於必須的劑量校正時，或是在掃描之後，下一組成η 條掃描線以相同的方式被選定並且被評估。這過程在橫越 6 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 141 --------------------訂---------^9. (請先閱讀背面之注意事項再填寫本頁) 1222099 A7 ____B7__ 五、發明說明（S ) 整組掃描線或是其中的子集合中重複，然後重複全部的過 程，直到劑量映射在規格之內。 根據本發明的另一個觀點，提供一種離子植入設備。 此種離子植入設備包括一離子束產生器，用以產生一離子 束；一掃描器，用以在第一方向掃描橫越工件的離子束產 生掃描線；一機械傳動器，在相對該離子束第二方向傳動 此工件，以使得掃描線在此工件中以一標準空間頻率分佈 ;劑量測量系統用以取得此工件的劑量映射，如果取得的 劑量映射不在規格之中以及必須的劑量校正小於由掃描線 的標準空間頻率所獲得的最小劑量校正時，控制器則用來 啓動劑量校正植入以及用來控制掃描線在整個劑量校正植 入期間的空間頻率。 圖式簡單說明 爲了得到本發明的更佳了解，附圖藉由參考合倂於本 發明，其中： 圖1是適合實現本發明之離子植入器之俯視槪要圖； 圖2是圖1之離子植入器的側視槪要圖； 圖3A是以掃描線爲函數的施加劑量百分率的圖表’ 其係當離子束在晶圓的中央附近而被中斷的情況。 圖3B是以掃描線爲函數的施加劑量百分率的圖表’ 其係在先前技術中劑量控制規則被用來校正如圖3A所示 之劑量數據圖表的情況。 圖3C是以掃描線爲函數的施加劑量百分率的圖表’ 7 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 142 --------------------訂--------- (請先閱讀背面之注意事項再填寫本頁) 1222099 A7 ___B7 _ 五、發明說明（匕） 其係用來顯示依照本發明實施例之劑量控制規則被用來校 正如圖3A所示之劑量數據圖表的情況； 圖4是依照本發明實施例，包含劑量控制之離子植入 過程的流程圖;以及 圖5是包含依照圖4所示之可變空間頻率劑量校正規 則實施例之流程圖。 元件符號說明 10·離子束產生器 12·離子束 16·掃描系統 20·掃描機 24·角度更正器 26·掃描產生器 30·掃描離子束 32·末端站 34·半導體晶圓 36·臺板 38·法拉第杯 40·機械傳動系統 42·傳動驅動器 44·位置感測器 50·系統控制器 60·離子束源 8 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 145 (請先閱讀背面之注意事項再填寫本頁)1222099 A7 B7 V. Description of the Invention (,) Cross-Reference to Related Applications This application claims the benefit of the provisional application serial number 60 / 293,754 filed on May 25, 2001, which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION The present invention relates to an ion implantation system and method for semiconductor wafers and other workpieces, and more particularly to an ion implantation system that uses a scanning line with a variable spatial frequency to control dose accuracy and dose uniformity. Into the system and method. BACKGROUND OF THE INVENTION Ion implantation is a standard technique for introducing impurities that can change conductivity into a semiconductor wafer. A desired impurity material is ionized in an ion source to accelerate these ions to form an ion beam with a specific energy. This ion beam is then directed onto the surface of the wafer. The ion with energy in the ion beam penetrates into the semiconductor material block and is embedded in the lattice of the semiconductor material 'to form a region having desired conductivity. Ion implantation systems often include an ion source that converts a gas or solid material into a well-defined ion beam. The ion beam is subjected to mass analysis to remove unwanted ion species, then accelerated to a desired energy and directed to the target plane. Most ion implanters use ion beams that are much smaller than the wafer in length and width, and electronically scan the ion beam to distribute the dose to the entire wafer, either by mechanically moving the wafer or by It is achieved through the combination of ion beam scanning and circular motion to achieve 3 paper sizes. Applicable to China National Standard (CNS) A4 (21 × 297 mm) (Please read the precautions on the back before filling this page) Order- ---- Φ 1222099 A7 _____B7 5. Description of the invention (〆) Completed. Ion implanters using a combination of electronic ion beam scanning and wafer mechanical motion were published in Berrian et al., U.S. Patent No. 4,922,106, published May 1, 1990, and in Berrian et al., 1990 I2 U.S. Patent No. 4,980,562 published on May 25. These patents describe techniques for controlling scans and doses in such systems. An important goal of scanning and dose control systems in ion implanters is to achieve dose accuracy and dose uniformity. That is, the ion implanter is required to implant a specific dose of doped atoms into the wafer and complete a specific dose uniformity across the wafer surface. In order to achieve dose uniformity and dose accuracy, ion implanters in the prior art use variable electronic scanning speeds and almost constant mechanical transfer speeds so that scan lines are uniformly distributed across the surface of the wafer. Complete wafer implantation involves several complete wafer pass overs until the desired total dose is reached. The spacing between the scan lines is typically smaller than the ion beam height in the mechanical transmission direction to ensure that the scan lines overlap and achieve uniform dose. As noted above, a typical implantation experiment planning may involve Multiple complete wafer transfers. The ion beam is scanned electronically on a Faraday cup, which measures the ion beam current at regular intervals during implantation. Dose measurement is used to generate a dose map of the implanted wafer. Because the dose mapping is based on the measured ion beam current, variations in the ion beam current are considered. Dose mapping is evaluated by the dose control system comparing it to a specific dose mapping. A dose-corrected scan is performed in areas where the actual dose is less than a specific dose. 4 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the notes on the back before filling this page) Order ------ 1222099 A7 __.__ B7___ V. Description of the invention ( )) (Please read the notes on the back before filling out this page) However, under certain conditions, dose correction cannot be used in the dose control algorithms in the conventional technology. In particular, the scanning system is characterized by a minimum dose correction that can be applied to the wafer. The minimum correction is produced by the following steps. The ion beam current is substantially fixed during a specific implantation, and based on the characteristics of the scan amplifier, the electronic scan speed has a maximum chirp. Therefore, the dose correction that can be applied to the wafer has a lower limit. If the required dose correction is less than the minimum correction, this desired dose cannot be achieved with previously known scanning techniques. If a minimum correction is applied to the wafer in this case, the actual dose will exceed the desired dose. If a minimum correction is not applied to this wafer, the actual dose will remain smaller than the desired dose. Accordingly, there is a need for improved ion implantation methods and equipment. The main point of the present invention is that the present invention is described in a manner related to a Lizi implanter, in which the ion beam is electronically scanned in one direction, usually in a horizontal direction, and the wafer or other workpiece is It is mechanically driven in a direction, generally in a vertical direction, to distribute the ion beam on the wafer surface. The electronic scanning of the ion beam produces scan lines, and the mechanical transmission of the wafer distributes the scan lines to the surface of the wafer. The spatial frequency of the scan lines on the wafer is controlled to control the dose and uniformity of the dose. According to a first aspect of the present invention, a method for ion implantation of a workpiece is provided. The method includes generating an ion beam, scanning the ion beam across a workpiece in a first direction to generate a scan line, and applying a Chinese National Standard (CNS) A4 specification (210 X 297) on the 5th and 7th paper dimensions related to the ion beam. Mm) 1222099 A7 ___._ B7 _ 5. Description of the invention (present) The workpiece is driven in two directions to distribute the scanning lines on the workpiece, and the spatial frequency of the scanning lines on the workpiece is controlled according to a desired dose map. According to another aspect of the present invention, a method for ion implantation of a workpiece is provided. The method includes generating an ion beam, scanning the ion beam across a workpiece in a first direction to generate a scan line, and driving the workpiece in a second direction relative to the ion beam, so that the scan line can be distributed on the workpiece at a standard spatial frequency. To obtain a dose map of the workpiece, and then start a dose correction implant if the obtained dose map is not in the specifications and the required dose correction is smaller than the minimum dose correction that can be obtained at the standard spatial frequency of the scan line And the spatial frequency of the scan lines is controlled throughout the duration of the dose correction implant. The step of controlling the spatial frequency of the scanning line may include (a) selecting a group of n scanning lines with a standard spatial frequency, where n represents the number of this group of scanning lines, and (b) determining whether the minimum dose correction is divided by a number 値 η Is less than or equal to the required dose correction, (c) if the minimum dose correction divided by the number 値 η is less than or equal to the required dose correction, start the ion beam scan in the selected scan line group, and (d) If the number of minimum dose correction divided by the number 値 η is not less than or equal to the necessary dose correction, and the number of scan lines η in the selected scan line group is less than a maximum 値 ' The number of scanning lines η is increased and steps (b)-(d) are repeated. When the number of scanning lines η in the selected scanning line group is equal to the maximum 値, and when the number of minimum dose correction divided by the number 値 η is not less than or equal to the necessary dose correction, or after scanning, the next The constituent n scanning lines are selected and evaluated in the same way. This process applies to 6 paper sizes across the Chinese National Standard (CNS) A4 (210 X 297 mm) 141 -------------------- Order --- ------ ^ 9. (Please read the precautions on the back before filling out this page) 1222099 A7 ____B7__ 5. Description of the Invention (S) Repeat for the entire set of scan lines or a subset of them, and then repeat the entire process Until the dose is mapped within specifications. According to another aspect of the present invention, an ion implantation device is provided. This ion implantation device includes an ion beam generator for generating an ion beam; a scanner for scanning an ion beam across a workpiece in a first direction to generate a scanning line; and a mechanical actuator for opposing the ion The workpiece is driven in the second direction so that the scanning line is distributed at a standard spatial frequency in the workpiece. The dose measurement system is used to obtain the dose map of the workpiece. If the obtained dose map is not in the specification and the required dose correction is less than When the minimum dose correction is obtained from the standard spatial frequency of the scan line, the controller is used to start the dose correction implantation and to control the spatial frequency of the scan line during the entire dose correction implantation. BRIEF DESCRIPTION OF THE DRAWINGS In order to obtain a better understanding of the present invention, the drawings are incorporated in the present invention by reference, wherein: FIG. 1 is a top view of an ion implanter suitable for implementing the present invention; FIG. 2 is a top view of FIG. A side view of the ion implanter is shown; FIG. 3A is a graph of the applied dose percentage as a function of a scan line. This is a case where the ion beam is interrupted near the center of the wafer. Fig. 3B is a graph of the percentage of applied dose as a function of the scan line ', which is a case where the dose control rule is used to correct the dose data graph shown in Fig. 3A in the prior art. Figure 3C is a graph of percentage of applied dose as a function of scan line. 7 This paper is sized to the Chinese National Standard (CNS) A4 (210 X 297 mm) 142 -------------- ------ Order --------- (Please read the notes on the back before filling out this page) 1222099 A7 ___B7 _ V. Description of the invention (dagger) It is used to display the embodiment according to the present invention The dose control rules are used to correct the situation of the dose data chart shown in FIG. 3A; FIG. 4 is a flowchart of an ion implantation process including dose control according to an embodiment of the present invention; and FIG. The flowchart of the embodiment of the variable spatial frequency dose correction rule is shown. Description of component symbols 10 · ion beam generator 12 · ion beam 16 · scanning system 20 · scanner 24 · angle corrector 26 · scan generator 30 · scan ion beam 32 · end station 34 · semiconductor wafer 36 · platen 38 · Faraday Cup 40 · Mechanical Drive System 42 · Drive Driver 44 · Position Sensor 50 · System Controller 60 · Ion Beam Source 8 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 145 ( (Please read the notes on the back before filling out this page)
· I n H ϋ n H 一 -ον I i^i I n n I 1222099 A7 ___B7___ 五、發明說明（1 ) 62·離子源過濾器 64·加速/減速縱列 70·質量分析器 72·二極分析磁鐵 74·光罩 76·解像光圈 80·掃描源頭 100、110、120·劑量曲線 112、114•區域 200、202、204、206、208、210、212、214、216、 250、252、254、256、258、260·步驟 本發明詳細描述 適用於結合本發明的離子植入器實施例的簡化方塊圖 顯示於圖1及圖2中。圖1是一個俯視圖，而圖2是一個 側視圖。在圖1和圖2中的相似元件具有相同的參考符號 〇 離子束產生器10產生希求種類的離子束，加速離子束 中的離子到一希求的能量，進行離子束的質量/能量分析以 除去能量及質量污染物並且供應具有低階之能量及質量污 染物之能量離子束12。一個包括掃描機20、一角度更正器 24和一掃描產生器26的掃描系統16，折射離子束以產生 具有平行或是幾乎平行離子軌跡的掃描過的離子束30。 末端站32包括一個臺板36，其支撐位於掃描離子束 9 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 14 4：' (請先閱讀背面之注意事項再填寫本頁)· I n H ϋ n H--ον I i ^ i I nn I 1222099 A7 ___B7___ V. Description of the invention (1) 62 · Ion source filter 64 · Acceleration / deceleration column 70 · Mass analyzer 72 · Dipole analysis Magnet 74, mask 76, resolution aperture 80, scan source 100, 110, 120, dose curve 112, 114, area 200, 202, 204, 206, 208, 210, 212, 214, 216, 250, 252, 254 256, 258, 260. Steps The detailed description of the present invention is shown in FIG. 1 and FIG. 2 as simplified block diagrams suitable for use in conjunction with an embodiment of the ion implanter of the present invention. Figure 1 is a top view and Figure 2 is a side view. Similar elements in FIGS. 1 and 2 have the same reference symbols. The ion beam generator 10 generates a desired type of ion beam, accelerates the ions in the ion beam to a desired energy, and performs mass / energy analysis of the ion beam to remove The energy and mass pollutants also supply energy ion beams 12 with lower order energy and mass pollutants. A scanning system 16 including a scanner 20, an angle corrector 24, and a scan generator 26 refracts the ion beam to produce a scanned ion beam 30 having parallel or nearly parallel ion trajectories. The end station 32 includes a platen 36, which supports the scanning ion beam 9. The paper size is applicable to Chinese National Standard (CNS) A4 (210 X 297 mm) 14 4: '(Please read the precautions on the back before filling in this page)
· I 訂------ 1222099 A7 _____B7__ 五、發明說明（名） 30之路徑中的半導體晶圓34或其他的工件，以使得含有 希求種類的離子被植入到半導體晶圓34裡。末端站32可 以包括一法拉第杯38以監控離子束的劑量以及劑量均勻性。 如圖2所顯示，離子植入機包括一個機械傳動系統40 ，用來在垂直方向機械地移動臺板36和晶圓34。機械傳 動系統40包括與臺板36和與位置感測器44機械地耦合的 傳動驅動器42，感測器44用來感知臺板36的垂直位置。 系統控制器50收到從法拉第杯38和位置感測器44發出的 信號，然後提供控制信號到掃描產生器26和傳動驅動器 42。透過舉例的方式，系統控制器50可以用程式化之一般 目的微處理器來實施，並搭配適當記憶體及其他的週邊裝 置。系統控制器50最好包括一劑量控制系統。 離子束產生器10可以包括離子束源60，一個離子源 過濾器62，一個加速/減速縱列64以及質量分析器70。離 子源過濾器62較佳爲定位於靠近離子束源60附近，加速/ 減速度縱列64定位在源過濾器62以及質量分析器70之間 。質量分析器70包括一個二極分析磁鐵72以及具有解像 光圈76的光罩74。 掃描器20可以是靜電式掃描器，折射離子束12以產 生具有從掃描源頭80發散之軌跡的掃描離子束。掃描器 20可以包括連接至掃描產生器26的間隙分離掃描平板。 掃描產生器26施加一掃描電壓波形，例如三角形波形，依 據幾個掃描平板之間的電場來掃描離子束。這個離子束一 般是在水平平面方向掃描的。 10 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 1'45· (請先閱讀背面之注意事項再填寫本頁) C:-------訂--------參 1222099 A7 __;___B7____ 五、發明說明（1 ) 角度校正器24被設計來折射掃描離子束中的離子，以 產生具有平行離子軌跡的掃描離子束30，如此將掃描離子 束聚焦。特別是，角度校正器24可以包括幾個磁極板，其 被分開設置以定義間隙以及與電源供應器(未顯示出)耦合 的磁鐵線圏。掃描的離子束經過極板之間的間隙然後依據 間隙中的磁場而折射。透過磁鐵線圈電流之改變可以調整 磁場大小。 在操作方面，掃描系統16在水平方向橫跨晶圓34來 掃描離子束12，而機械傳動系統40將臺板36和晶圓34在 垂直於掃描離子束30的方向傳動。掃描系統16在晶圓34 的表面上產生掃描線。結合離子束12的電子式掃描和晶圓 34的機械傳動致使掃描線分布在晶圓34的表面上。當臺 板36處於一個較低的位置時，離子束電流由法拉第杯38 '測i ’然後代表離子束電流的信號被提供給系統控制器50 。在另一個實施例中，法拉第杯放置在晶圓34附近並且間 歇掃描。電子式掃描之速度能夠以水平的離子束位置 作爲函數來變化，以達到劑量的均勻性。 一^固半導體晶圓的傳統植入涉及多個完整的晶圓轉寫 ’ Μ胃&特定束電流以及掃描協定來達到希求的劑量。例 如’晶_的十次完全轉寫可以被要求以達到規定的劑量， 而i更大數量的轉寫可以被要求以達到更高的劑量。「轉 寫」指的是電子掃描以及將離子束分配到晶圓上之機械傳 重力白勺，結合。在一個範例中，離子束進行電子式掃描並且被 機械地傳動以產生每英吋大約40條掃描線的標準空間頻率 _11 t 紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公麓） --------------------訂--------- <請先閱讀背面之注意事項再填寫本頁) 1222099 A7 ____B7___ 五、發明說明) 。因此，一個大晶圓的完整轉寫可能需要數百個掃描線。 一般而言，離子束在機械傳動方向的高度大約爲一公分或 是更高。因此，每英吋具有40條掃描線空間頻率的掃插協 定造成掃描線的重疊並且增進劑量均勻性。在植入期間， 從離子束電流的測量產生了劑量映射’劑量映射代表在晶 圓表面區域的離子劑量’也因此提供晶圓的劑量輪廓，包 括劑量以及劑量的均勻性。隨著植入的過程以及每一晶圓 的轉寫被完成，劑量映射被更新’然後劑量濃度與希求的 劑量濃度在晶圓上的若干位置作比較。當到達希求的劑量 濃度時終止植入。 與希求劑量映射的偏差可能由一些來源產生’包括離 子束的閃動及離子束的漂移。此外，如果植入室裏的壓力 因爲例如，光阻的氣體逸出而造成外部規定之限度的超出 ，離子植入器一般會進行互鎖以關閉離子束。當壓力超出 指定的限制時，離子束被關閉直到恢復到希求的壓力。這 樣，所給定的植入易受到離子束電流變化的影響’包括離 子束的關閉。這種離子束電流的變化負面地影響劑量映射。 參考圖3Α，顯示一種劑量映射，其中施加的希求劑量 百分率以掃描線數目作爲函數的方式來畫出。在圖3Α的 一個範例中，該植入具有600條掃描線，掃描線〇代表晶 圓的底部，而掃描線600代表晶圓的頂部。劑量曲線100 說明一個範例，其中離子束在掃描線0到200之間被中斷 ，然後在掃描線200到400之間逐漸恢復。可以看到在晶 圓的較低部分劑量明顯地低於希求的劑量。 12 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） ί請先閱讀背面之注意事項再填寫本頁) 訂------ 龜· 1222099 五、發明說明（\\ ) 依照習知技術的劑量控制規則，關於圖3A中離子束 電流的反應顯示於圖3B中。此劑量控制系統決定在晶圓 較低部分的劑量是否在規格以下，其係透過經由劑量映射 所表示的實際劑量與希求劑量的比較來獲得。進行劑量校 正植入以增加晶圓較低部分的劑量達到規定劑量的百分之 百。這是由具有標準空間頻率的掃描線來掃描晶圓的較低 部分，直到實際劑量儘可能地接近規定的劑量。 如同在圖3B中顯示的，劑量曲線110展現出在晶圓中 心附近的一個區域112，在其中實際劑量低於希求劑量， 在區域112中劑量減少的原因如下。區域112的位置與圖 3A中之區域114 一致，其中劑量稍微低於希求的劑量。這 樣的話，在區域114中需要相對小的劑量校正。然而，習 知技術劑量控制系統被能施加的最小劑量校正所特徵化。 最小校正源自於離子束電流以及掃描協定被固定的事實。 在上面範例中所述的掃描協定具有每英吋40條掃描線的標 準空間頻率，其被用來在晶圓表面上確保劑量均勻性。劑 量校正可以由電子式掃描速度的增加來降低，從而降低了 每單位面積之離子植入數目。然而，電子的掃描速度具有 由掃描產生器26(圖2)之特性決定的一個最大數値。結果 ，先前習知技術之劑量控制系統受到因掃描線的標準空間 頻率所能得到的最小劑量校正而被限制。最小劑量校正隨 植入處方變化，但只能達到5至10%的範圍。如果這個晶 圓在一個區域中使用最小劑量校正進行掃描，例如在區域 114，其中最小劑量校正大於需求的劑量校正，那麼實際的 13 (請先閱讀背面之注意事項再填寫本頁) --------訂--------- 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 1222099 A7 ____B7____ 五、發明說明（|X) 劑量將會超過這個希求的劑量。劑量控制系統一般被設計 來避免超過希求的劑量。因此，當最小劑量校正比需求的 劑量校正大時，不使用最小劑量校正，因而區域112是劑 量不足的。這樣的劑量不足是不被半導體製造商接受的。 依據本發明的一個特性，可以控制掃描線的空間頻率 以得到希求的劑量曲線。尤其是，掃描線的標準空間頻率 在晶圓的一些區域中降低，這些區域需要一個比由掃描線 標準空間頻率所能得到的最小劑量校正還低的劑量校正。 具有標準空間頻率的一組掃描線可以用單一掃描線來掃描 。如此舉例來說，具有標準空間頻率的三條掃描線，每一 條具有需求最小劑量校正的三分之一，其以越過三條掃描 線中心由單一的掃描來進行校正。此種處理可以在橫越整 個晶圓表面或是晶圓表面的一個選定的部分重複進行，該 技術依賴於在機械傳動方向的離子束高度較對應於掃描線 標準空間頻率的掃描線間距更大的一個事實。一組掃描線 係定義爲，二個或是更多個具有掃描協定之標準空間頻率 的鄰接掃描線。掃描線組的數目依據需求劑量校正的量級 決定。一組掃描線的最大數目取決於在機械傳動方向的離 子束高度。用來生產希求劑量映圖的技術，如在圖3C中 的劑量曲線120所說明的範例中展示。當使用這個發明時 ，可以由掃描線的標準空間頻率得到的最小劑量校正不再 對劑量校正產生一個下限。 在一組掃描線中具有標準空間頻率的掃描線的數目η 可以由將最小劑量校正除以需求的劑量校正來選擇，而其 14 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 識. (請先閱讀背面之注意事項再填寫本頁) 訂------ 1222099 A7 ^__._B7 __ 五、發明說明（〇) 中最小劑量校正係以掃描線的空間頻率來得到，如此舉例 來說，當最小劑量校正是10%而且需求的劑量校正是2%， 則該組掃描線的數目η爲10/2=5。如果從最小劑量校正除 以劑量校正所得到的數目η不是一個整數値時，η的數値 被進位到下一個更大的整數。在以下描述的相等處理中， 選擇具有掃描線較小數目η的一組掃描線，然後增加數目 η直到最小劑量校正除以數目η的値小於或是等於需求的 劑量校正。當需求的劑量校正依據劑量映射變化時，該組 掃描線的數目η可以在晶圓的表面上變化。該組掃描線的 最大數量n_max可以由機械掃描方向的離子束高度除以在 掃描線之間的標準間距來決定。這可以確保了該組掃描線 的單一掃描涵蓋該組的所有掃描線。 圖4展示了一個含有依照本發明實施例之劑量控制的 離子植入處理流程圖。系統控制器50(圖2)中的一個軟體 用來實施該處理並且用來控制掃描產生器26以及傳動驅動 器42。 參考圖4，在步驟200中產生了一個離子束，該離子 束可以由在圖1展示並且在以上描述的離子束產生器來產 生。在步驟202中，這個離子束由掃描系統16在第一方向 橫越一個半導體晶圓或是其他工件來進行掃描，並且由機 械傳動系統40在與掃描離子束相關的第二方向傳動這個晶 圓。一個植入依據特定的植入配方來完成，以提供晶圓中 的特定劑量的摻雜離子。需求的劑量精確度和劑量均勻性 一般最好大於1%。 15 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） -----------裝--------訂--------- (請先閱讀背面之注意事項再填寫本頁) 1222099 A7 ___._E7___ 五、發明說明（w) 在步驟204中，獲得了晶圓的一劑量圖。在植入期間 ，劑量圖可以由系統控制器50產生，其係根據法拉第杯 38對離子束測量的反應。劑量圖表示了半導體晶圓中包括 劑量和劑量均勻性的劑量曲線。當植入進行時劑量圖可以 以累積的方式獲得;植入可能需要一個或是更多個晶圓表面 的完整轉寫。 在步驟206中，決定了劑量校正是否需要。評估所獲 得的劑量圖，其係一般由劑量圖之若干位置中把處方的特 定劑量與測量到的劑量比較來得到。劑量校正是否需要的 決定可以基於劑量圖是否符合劑量和劑量均勻性的預定標 準。在一個實施例中，如果:(1)獲得的劑量圖的均勻性比預 定的値還小(這個狀況可以在植入的任何時間發生），或是 (2)不論獲得的劑量圖均勻與否(這個狀況可以在植入快結束 時發生，當希求劑量與測量到的劑量之間的差別較最小量 劑量校正小時劑量校正是需要的。如果不需要劑量校正， 植入則繼續進行，直到植入達到希求的劑量。 如果步驟206決定劑量校正是不需要的.，那麼步驟 208決定植入是否完成。如果植入就劑量和劑量均勻性而 論已經完成，那麼處理在步驟210中完成。如果步驟208 決定植入尙未完成，處理回到步驟202以進行額外的橫越 工件及傳動晶圓的離子束掃描。一般的植入可能需要在半 導體晶圓上若干的完整掃描或是轉寫。 如果步驟206決定劑量校正是需要的，那麼處理前進 到步驟212。在步驟212中，決定了所需的劑量校正是否 16 央紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁) C--------?! 1222099 A7 __· _ B7 _ 五、發明說明（V〇 比能夠由掃描線的標準空間頻率所能得到的最小劑量校正 還小。最小劑量校正一般爲一已知量，其係是離子束電流 ，離子束截面積，最大掃描速度以及掃描線標準空間頻率 的函數。如果在步驟212中決定了需要的劑量校正並不比 最小劑量校正小時，傳統的劑量校正規則於步驟214中使 用。劑量校正規則可以包括掃描波形的調整以獲得希求劑 量的分配。更特別地，在需要增加的劑量的區域，掃描速 度可以被降低，而且在需要減少劑量的區域，增加掃描速 度。然後回到步驟202，以校正過的波形進行半導體晶圓 的處理。 如果在步驟212中決定了需求的劑量校正比最小劑量 校正小時，處理回到步驟216。在步驟216中，利用了可 變的空間頻率劑量校正規則。典型地，在接近植入快結束 的時候，這個可變空間頻率的劑量校正規則被使用。例如 ，假設能夠由掃描線的標準空間頻率獲得的最小劑量校正 是10%，而且從獲得的劑量圖所決定之植入到晶圓裡的離 子束劑量是希求的劑量的95%。在這種情況下，利用最小 劑量校正的傳統的劑量校正規則將產生晶圓的5%劑量過多 。因此，需要使用可變空間頻率的劑量校正規則。可變空 間頻率的劑量校正規則的一個實施例將在下面以結合圖5 的方式描述。在步驟216之後，處理回到步驟206以決定 額外的劑量校正是否需要。或者是，植入處理在步驟216 之後可以視爲已經完成。 在圖5中展示了一個可變空間頻率劑量校正規則實施 17 夸紙張尺度中關家標準（CNS)A4規格（210 X 297公釐) _ ~ 152 -----------裝--------訂--------- (請先閱讀背面之注意事項再填寫本頁) 1222099 五、發明說明（丨么） 例的流程圖。一組具有標準空間頻率的η條掃描線在步驟 250中被選定，其中η表示該組掃描線的數目。起始選定 的一組掃描線一般在需要劑量校正的區域上或是靠近其一 邊。需要劑量校正的區域可能包括整個晶圓或是晶圓的一 個部分。在圖3Β的範例中，需要校正的區域112位於晶圓 的中心附近。在步驟250中選定的初始掃描線組可以包括 二條鄰近的掃描線。 在步驟252中，決定了最小劑量校正是否小於或是等 於需求的劑量校正。該最小劑量校正可以由掃描線的標準 的空間頻率除以在一組掃描線組裡的掃描線的數目η來得 到。因此，舉例來說，如果包括兩條(η=2)掃描線的一組掃 描線中，最小劑量校正是10%並且需求的劑量校正是2%， 那麼最小劑量校正除以η不小於或是等於需求的劑量校正 。如果上面所述範例的需求的劑量校正改變爲5%，那麼最 小劑量校正除以η是小於或是等於需求的劑量校正。當在 步驟252中決定了最小劑量校正除以η是小於或是等於需 求的劑量校正時，該具有η條掃描線的一組掃描線在步驟 254中進行掃描，最好是使用在選定的該組η條掃描線之 中心或是其附近進行單一的掃描。 如果在步驟252中決定了最小劑量校正除以η不小於 或是等於需求的劑量校正時，在步驟256中決定該組掃描 線的數目η條是否等於一個最大値n_max。該組裡掃描線 的最大數目n_max可以以機械傳動方向的離子束高度做基 礎。典型的離子束高度是一公分或是更大。這樣，對於每 18 -----------裝--------訂---------^9 (請先閱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（210 X 297公釐） 1222099 A7 ___._B7_____ 五、發明說明（\1 ) 英吋40條掃描線的標準空間頻率來說，掃描線的最大數目 n__max可以是15或是更大的一個數。如果掃描的數目線等 於最大値n_max，不進行任何劑量校正並且處理前進到步 驟260。在這種情況下不進行劑量校正以避免超過希求的 劑量。 如果在步驟256中決定了掃描線的數目小於最大數目 n_max，該組掃描線的數目η在步驟258中被增加，典型 地增加一條掃描線，然後處理回到步驟252。在步驟252 中決定了最小劑量校正除以新數値η是小於或是等於新選 定的一組掃描線的需求劑量校正。該組掃描線的數目 n_max被增加，直到最小劑量校正除以新數値η是小於或 是等於需求劑量校正，或是直到達到該組掃描線的最大數 目n_max。如果最小劑量校正除以該組掃描線的數目η是 小於或是等於所需求之劑量校正時，該組η條掃描線在步 驟254中被掃描，較佳是以在該組掃描線中央或是其中央 附近的單一掃描來進行。在該組掃描線中央或是其中央附 近的掃描可以由延遲掃描線的起始點的方式完成，該起始 點係與晶圓至掃描線的位置或是掃描線的中心附近的機械 傳動相關。 在上面所述範例中需求的劑量校正是2%並且最小劑量 校正是10%。劑量校正規則的可變空間頻率利用了一組五 條的鄰接掃描線。在這種情況下，劑量校正在一組五條掃 描線的中央或是其中央附近的單一掃描來進行，其中該離 子束係被分配到該組中的所有掃描線的方式。 19 Α紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公麓） 15% (請先閱讀背面之注意事項再填寫本頁) --------訂----I---- 1222099 A7 --2L_-——_ 五、發明說明（ 在步驟260做出有關目前的掃描線組是否需求劑量校 正的最後一組的決定。如果目前的這一組不是最後一組， 處理回到步驟250,然後選擇新的一組具有標準空間頻率 的η條掃描線。新的一組可以與以前的一組緊鄰，在越過 需要劑量校正的區域中以有秩序的模式進行。或者是，新 的一組可以在需要劑量校正的晶圓的另一個區域中。在上 面描述的處理中，重複每一組被選定的掃描線，直到需要 劑量校正的區域已經完成。增加每一組掃描線的數目直到 最小劑量校正除以該組掃描線的數目η所得的値小於或是 等於所需的劑量校正爲止。當該晶圓利用此可變的空間頻 率劑量校正規則來掃描時，由法拉第杯38得到劑量圖的更 新版(如圖2所示）。 如果目前的掃描線組在步驟260中決定是需要校正的 最後一組，處理回到步驟206(圖4)。在步驟206中決定了 進一步的劑量校正是否需要，如此，處理驗證可變空間頻 率的劑量校正規則已經達到需求的劑量圖。或者是，該植 入不用進一步的劑量圖確認，而在步驟260之後視爲已經 完成。 本揭示的技術具有可以降低掃描線的空間頻率的效果 ’該空間頻率係與標準的空間頻率相關，並且具有降低可 以^皮施加到晶圓的劑量校正。透過每一掃描線組的掃描線 數量變化，掃描線的標準空間頻率以及劑量校正可以被調 整以提供需求的劑量校正。因此相對低的掃描線空間頻率 可以用來獲得較小量的劑量校正。相反地，掃描線的一個 20 (請先閱讀背面之注意事項再填寫本頁) —訂--------參 紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 1222099 A7 _____B7____ 五、發明說明（l/ ) 相對高的空間頻率被用來獲得更大的劑量校正。 在植入快要結束的時候’可以利用可變的空間頻率劑 量校正規則來進行劑量校正。劑量校正可以在晶圓的選定 區域或是在整個晶圓表面上完成。在另一個實施例中’可 以利用掃描線空間頻率的控制來完成低劑量的植入。當使 用標準的掃描協定單一轉寫晶圓時’造成劑量超過規定劑 量的情況時，此種方法可以被使用。如此掃描線空間頻率 的控制可以提供進行低植入劑量的一個技術。 在圖5的範例中，固定了一組內部之掃描線的最大數 目n_max。在另一個實施例中，一組掃描線裡的掃描線最 大數目可以在機械傳動方向依據離子束高度來進行調整或 是程式化。在相對高的離子束中，一組掃描線裡的掃描線 最大數目n_max可以被增加，從而增加可能劑量校正的範 圍。 儘管已描述本發明的較佳實施例之呈現，很明顯對於 那些熟悉習知技術的人來說，在不背離如附加的本專利申 請範圍所定義的範圍，各種變化和修正可以進行。 21 ―本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 15b -----------41^ 裝--------訂--------- (請先閱讀背面之注意事項再填寫本頁)· I order ------ 1222099 A7 _____B7__ 5. The semiconductor wafer 34 or other workpieces in the path of the invention (name) 30, so that the ions containing the desired type are implanted into the semiconductor wafer 34. The end station 32 may include a Faraday cup 38 to monitor the dose of the ion beam and dose uniformity. As shown in FIG. 2, the ion implanter includes a mechanical transmission system 40 for mechanically moving the platen 36 and the wafer 34 in a vertical direction. The mechanical drive system 40 includes a drive driver 42 mechanically coupled to the platen 36 and a position sensor 44 for sensing the vertical position of the platen 36. The system controller 50 receives signals from the Faraday cup 38 and the position sensor 44 and then provides control signals to the scan generator 26 and the drive driver 42. By way of example, the system controller 50 may be implemented with a programmed general purpose microprocessor, with appropriate memory and other peripherals. The system controller 50 preferably includes a dose control system. The ion beam generator 10 may include an ion beam source 60, an ion source filter 62, an acceleration / deceleration column 64, and a mass analyzer 70. The ion source filter 62 is preferably positioned near the ion beam source 60, and the acceleration / deceleration column 64 is positioned between the source filter 62 and the mass analyzer 70. The mass analyzer 70 includes a two-pole analysis magnet 72 and a mask 74 having a resolution aperture 76. The scanner 20 may be an electrostatic scanner that refracts the ion beam 12 to produce a scanned ion beam having a trajectory diverging from the scanning source 80. The scanner 20 may include a gap-separated scanning plate connected to the scan generator 26. The scan generator 26 applies a scanning voltage waveform, such as a triangular waveform, to scan the ion beam based on the electric field between several scanning plates. This ion beam is typically scanned in a horizontal plane. 10 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 1'45 · (Please read the precautions on the back before filling this page) C: ------- Order --- ----- Refer to 1222099 A7 __; ___ B7____ 5. Description of the invention (1) The angle corrector 24 is designed to refract the ions in the scanned ion beam to produce a scanned ion beam 30 with parallel ion trajectories, so the ion beam will be scanned Focus. In particular, the angle corrector 24 may include several magnetic pole plates that are separately provided to define a gap and a magnet wire coil coupled to a power supply (not shown). The scanned ion beam passes through the gap between the plates and is refracted according to the magnetic field in the gap. The magnetic field can be adjusted by changing the current of the magnet coil. In operation, the scanning system 16 scans the ion beam 12 across the wafer 34 in a horizontal direction, and the mechanical transmission system 40 drives the platen 36 and the wafer 34 in a direction perpendicular to the scanning ion beam 30. The scanning system 16 generates scan lines on the surface of the wafer 34. Combining the electronic scanning of the ion beam 12 and the mechanical transmission of the wafer 34 causes scan lines to be distributed on the surface of the wafer 34. When the platen 36 is in a lower position, the ion beam current is measured by the Faraday cup 38 and the signal representing the ion beam current is provided to the system controller 50. In another embodiment, a Faraday cup is placed near the wafer 34 and scanned intermittently. The speed of the electronic scan can be varied as a function of horizontal ion beam position to achieve uniform dose. The traditional implantation of a solid semiconductor wafer involves multiple complete wafer transfers ′ M stomach & specific beam currents and scanning protocols to achieve the desired dose. For example, ten complete transliterations of 'Crystalline' may be required to achieve a prescribed dose, while a larger number of transliterations of i may be required to achieve a higher dose. "Transfer" refers to the combination of electronic scanning and mechanical transmission of the ion beam onto the wafer. In one example, the ion beam is scanned electronically and mechanically driven to produce a standard spatial frequency of about 40 scan lines per inch_11 t paper size applicable to China National Standard (CNS) A4 (210 X 297 foot) ) -------------------- Order --------- < Please read the notes on the back before filling this page) 1222099 A7 ____B7___ V. Description of the invention). Therefore, a full transfer of a large wafer may require hundreds of scan lines. Generally, the height of the ion beam in the direction of the mechanical transmission is about one centimeter or higher. Therefore, a sweeping agreement with a spatial frequency of 40 scan lines per inch causes overlapping scan lines and improves dose uniformity. During implantation, a dose map is generated from the measurement of the ion beam current. The dose map represents the ion dose at the wafer surface area and thus provides the wafer's dose profile, including dose and dose uniformity. As the implantation process and the transfer of each wafer are completed, the dose map is updated 'and the dose concentration is compared with the desired dose concentration at several locations on the wafer. Implantation is terminated when the desired dose concentration is reached. Deviations from the desired dose mapping may arise from a number of sources ' including flicker of the ion beam and drift of the ion beam. In addition, if the pressure in the implantation chamber exceeds an externally prescribed limit due to, for example, the escape of a photoresist gas, the ion implanter typically interlocks to shut off the ion beam. When the pressure exceeds the specified limit, the ion beam is turned off until the desired pressure is restored. In this way, a given implant is susceptible to changes in the ion beam current ', including the closing of the ion beam. This change in ion beam current negatively affects the dose mapping. Referring to FIG. 3A, a dose map is shown in which the percentage of the applied desired dose is plotted as a function of the number of scan lines. In an example of FIG. 3A, the implant has 600 scan lines, scan line 0 represents the bottom of the wafer, and scan line 600 represents the top of the wafer. The dose curve 100 illustrates an example where the ion beam is interrupted between scan lines 0 to 200 and then gradually recovered between scan lines 200 to 400. It can be seen that the dose in the lower part of the wafer is significantly lower than the desired dose. 12 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) ί Please read the precautions on the back before filling out this page) Order ------ Turtle · 1222099 V. Description of the invention (\\ ) The response to the ion beam current in FIG. 3A is shown in FIG. 3B according to the conventional dose control rules. This dose control system determines whether the dose in the lower part of the wafer is below the specification, which is obtained by comparing the actual dose represented by the dose map with the desired dose. Dose correction implantation was performed to increase the dose of the lower part of the wafer to 100% of the prescribed dose. This is done by scanning the lower part of the wafer with scan lines with standard spatial frequencies until the actual dose is as close as possible to the prescribed dose. As shown in FIG. 3B, the dose curve 110 shows an area 112 near the center of the wafer in which the actual dose is lower than the desired dose, and the reason for the dose reduction in the area 112 is as follows. The location of area 112 is consistent with area 114 in Figure 3A, where the dose is slightly lower than the desired dose. As such, a relatively small dose correction is required in the region 114. However, conventional technology dose control systems are characterized by a minimum dose correction that can be applied. The minimum correction results from the fact that the ion beam current and the scanning protocol are fixed. The scan protocol described in the example above has a standard spatial frequency of 40 scan lines per inch, which is used to ensure dose uniformity on the wafer surface. Dose correction can be reduced by increasing the electronic scanning speed, which reduces the number of ion implantations per unit area. However, the scanning speed of the electrons has a maximum number determined by the characteristics of the scan generator 26 (Fig. 2). As a result, the dose control system of the prior art is limited by the minimum dose correction that can be obtained by the standard spatial frequency of the scan line. The minimum dose correction varies with implantation prescription, but can only reach the range of 5 to 10%. If this wafer is scanned using the minimum dose correction in an area, such as area 114, where the minimum dose correction is greater than the required dose correction, then the actual 13 (please read the precautions on the back before filling this page) --- ----- Order --------- This paper size applies to Chinese National Standard (CNS) A4 (210 X 297 mm) 1222099 A7 ____B7____ 5. Description of the invention (| X) The dosage will exceed this The desired dose. Dose control systems are generally designed to avoid exceeding the desired dose. Therefore, when the minimum dose correction is larger than the required dose correction, the minimum dose correction is not used, and thus the region 112 is underdosed. Such an underdose is not acceptable to semiconductor manufacturers. According to a characteristic of the present invention, the spatial frequency of the scanning line can be controlled to obtain a desired dose curve. In particular, the standard spatial frequency of the scan line is reduced in areas of the wafer that require a lower dose correction than the minimum dose correction that can be obtained from the standard spatial frequency of the scan line. A set of scan lines with standard spatial frequencies can be scanned with a single scan line. As an example, three scan lines with a standard spatial frequency, each with one-third of the required minimum dose correction, are corrected by a single scan across the center of the three scan lines. This process can be repeated across the entire wafer surface or a selected portion of the wafer surface. The technology relies on the ion beam height in the mechanical transmission direction being greater than the scan line spacing corresponding to the standard spatial frequency of the scan line. A fact. A set of scan lines is defined as two or more adjacent scan lines with a standard spatial frequency of the scan protocol. The number of scan line groups is determined by the magnitude of the required dose correction. The maximum number of scan lines in a group depends on the ion beam height in the direction of the mechanical drive. The technique used to produce the desired dose map is shown in the example illustrated by the dose curve 120 in Figure 3C. When using this invention, the minimum dose correction that can be obtained from the standard spatial frequency of the scan line no longer places a lower limit on the dose correction. The number of scan lines with a standard spatial frequency in a set of scan lines η can be selected by dividing the minimum dose correction by the required dose correction, and its 14 paper sizes are applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 (Please read the notes on the back before filling this page) Order ------ 1222099 A7 ^ __._ B7 __ 5. The minimum dose correction in the description of the invention (〇) is based on the spatial frequency of the scanning line To get, for example, when the minimum dose correction is 10% and the required dose correction is 2%, the number of scanning lines η is 10/2 = 5. If the number η obtained by dividing the minimum dose correction by the dose correction is not an integer 値, the number η of η is rounded to the next larger integer. In the equal processing described below, a set of scan lines having a smaller number of scan lines η is selected, and the number η is increased until the minimum dose correction divided by the number η is less than or equal to the required dose correction. When the required dose correction varies according to the dose map, the number η of the set of scan lines may vary on the surface of the wafer. The maximum number of scanning lines in this group, n_max, can be determined by dividing the ion beam height in the mechanical scanning direction by the standard spacing between the scanning lines. This ensures that a single scan of the set of scan lines covers all scan lines of the group. Figure 4 shows a flowchart of an ion implantation process including dose control according to an embodiment of the present invention. A piece of software in the system controller 50 (Fig. 2) is used to implement this process and to control the scan generator 26 and the drive driver 42. Referring to FIG. 4, an ion beam is generated in step 200, and the ion beam may be generated by the ion beam generator shown in FIG. 1 and described above. In step 202, the ion beam is scanned by a scanning system 16 across a semiconductor wafer or other workpiece in a first direction, and the wafer is driven by a mechanical transmission system 40 in a second direction related to scanning the ion beam. . An implant is done according to a specific implant formulation to provide a specific dose of doped ions in the wafer. The required dose accuracy and dose uniformity are generally better than 1%. 15 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) ----------- installation -------- order --------- (Please read the notes on the back before filling this page) 1222099 A7 ___._ E7___ V. Description of the invention (w) In step 204, a dose map of the wafer is obtained. During implantation, a dose map may be generated by the system controller 50, which is based on the response of the Faraday cup 38 to the ion beam measurement. The dose graph shows a dose curve including the dose and the dose uniformity in a semiconductor wafer. Dose maps can be obtained cumulatively as implantation progresses; implantation may require complete transcription of one or more wafer surfaces. In step 206, it is determined whether a dose correction is required. The dose map obtained by the evaluation is generally obtained by comparing the prescribed specific dose with the measured dose in several positions of the dose map. The decision whether a dose correction is needed can be based on whether the dose map meets predetermined criteria for dose and dose uniformity. In one embodiment, if: (1) the uniformity of the obtained dose map is smaller than the predetermined value (this condition can occur at any time of implantation), or (2) whether the obtained dose map is uniform or not (This condition can occur near the end of implantation. When the difference between the desired dose and the measured dose is smaller than the minimum dose correction, hourly dose correction is needed. If dose correction is not required, implantation continues until the implantation The desired dose is reached. If step 206 determines that dose correction is not required, then step 208 determines whether the implantation is complete. If the implantation has been completed in terms of dose and dose uniformity, then processing is completed in step 210. If Step 208 determines that the implantation is not completed, and the process returns to step 202 for additional ion beam scanning across the workpiece and the transmission wafer. The general implantation may require several complete scans or transfers on the semiconductor wafer. If step 206 determines that a dose correction is needed, then the process proceeds to step 212. In step 212, it is determined whether the required dose correction is a 16-centimeter paper rule. Applicable to China National Standard (CNS) A4 specification (210 X 297 mm) (Please read the precautions on the back before filling this page) C -------- ?! 1222099 A7 __ · _ B7 _ V. Invention Explanation (V0 is smaller than the minimum dose correction that can be obtained from the standard spatial frequency of the scan line. The minimum dose correction is generally a known quantity, which is the ion beam current, the cross-sectional area of the ion beam, the maximum scan speed, and the scan. A function of the standard spatial frequency of the line. If it is determined in step 212 that the required dose correction is not less than the minimum dose correction, a conventional dose correction rule is used in step 214. The dose correction rule may include adjustment of the scanning waveform to obtain the desired dose Distributing. More specifically, the scanning speed can be reduced in the area where the dose needs to be increased, and the scanning speed can be increased in the area where the dose needs to be reduced. Then return to step 202 to process the semiconductor wafer with the corrected waveform. If it is determined in step 212 that the required dose correction is smaller than the minimum dose correction, the process returns to step 216. In step 216, the available Variable spatial frequency dose correction rule. Typically, this variable spatial frequency dose correction rule is used near the end of implantation. For example, suppose the minimum dose correction that can be obtained from the standard spatial frequency of the scan line is 10 %, And the dose of ion beam implanted into the wafer determined from the obtained dose map is 95% of the desired dose. In this case, the conventional dose correction rule using the minimum dose correction will generate the wafer's The 5% dose is too much. Therefore, a dose correction rule with a variable spatial frequency is required. An embodiment of the dose correction rule with a variable spatial frequency will be described below in conjunction with FIG. 5. After step 216, the process returns to step 206 to determine if additional dose correction is needed. Alternatively, the implantation process may be considered completed after step 216. Figure 5 shows the implementation of a variable spatial frequency dose correction rule in a 17-quart paper standard (CNS) A4 specification (210 X 297 mm) _ ~ 152 ----------- install -------- Order --------- (Please read the notes on the back before filling out this page) 1222099 V. Description of the invention (丨) Example flow chart. A group of n scanning lines with a standard spatial frequency is selected in step 250, where n represents the number of the group of scanning lines. The initial set of scan lines is usually on or near the area where dose correction is needed. The area requiring dose correction may include the entire wafer or a portion of the wafer. In the example of Fig. 3B, the area 112 to be corrected is located near the center of the wafer. The initial scan line group selected in step 250 may include two adjacent scan lines. In step 252, it is determined whether the minimum dose correction is less than or equal to the required dose correction. The minimum dose correction can be obtained by dividing the standard spatial frequency of the scan lines by the number? Of scan lines in a scan line group. So, for example, if a set of scan lines including two (η = 2) scan lines has a minimum dose correction of 10% and a required dose correction of 2%, then the minimum dose correction divided by η is not less than Equal to the required dose correction. If the required dose correction for the example described above is changed to 5%, then the minimum dose correction divided by η is less than or equal to the required dose correction. When it is determined in step 252 that the minimum dose correction divided by η is less than or equal to the required dose correction, the set of scanning lines with n scanning lines is scanned in step 254, and it is best to use the selected A single scan is performed at or near the center of the n scanning lines. If it is determined in step 252 that the minimum dose correction divided by η is not less than or equal to the required dose correction, it is determined in step 256 whether the number η of the set of scan lines is equal to a maximum 値 n_max. The maximum number of scan lines in this group, n_max, can be based on the ion beam height in the direction of the mechanical transmission. A typical ion beam height is one centimeter or more. In this way, for every 18 ----------- install -------- order --------- ^ 9 (Please read the precautions on the back before filling this page) This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 1222099 A7 ___._ B7_____ V. Description of the invention (\ 1) For the standard spatial frequency of 40 scanning lines in inches, the maximum number of scanning lines n__max can be a number of 15 or greater. If the number of scans is equal to the maximum 値 n_max, no dose correction is performed and the process proceeds to step 260. No dose correction is performed in this case to avoid exceeding the desired dose. If it is determined in step 256 that the number of scan lines is less than the maximum number n_max, the number of scan lines η of the group is increased in step 258, typically one scan line is added, and then the process returns to step 252. It is determined in step 252 that the minimum dose correction divided by the new number 値 η is less than or equal to the required dose correction for a newly selected set of scan lines. The number of scan lines n_max of the group is increased until the minimum dose correction divided by the new number 値 η is less than or equal to the required dose correction, or until the maximum number of scan lines n_max is reached. If the minimum dose correction divided by the number of scan lines η is less than or equal to the required dose correction, the set of η scan lines are scanned in step 254, preferably in the center of the set of scan lines or A single scan is performed near its center. Scanning at or near the center of the set of scan lines can be done by delaying the starting point of the scan line, which is related to the position of the wafer to the scan line or the mechanical transmission near the center of the scan line . The required dose correction in the example described above is 2% and the minimum dose correction is 10%. The variable spatial frequency of the dose correction rule uses a set of five contiguous scan lines. In this case, the dose correction is performed in a single scan at or near the center of a group of five scan lines, where the ion beam is assigned to all the scan lines in the group. 19 Α paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 feet) 15% (Please read the precautions on the back before filling this page) -------- Order ---- I- --- 1222099 A7 --2L _-——_ V. Description of the invention (At step 260, a decision is made as to whether the current scan line group requires the last group of dose correction. If the current group is not the last group, Processing returns to step 250 and then selects a new set of n scan lines with standard spatial frequencies. The new set can be immediately adjacent to the previous set and proceed in an orderly pattern across the area requiring dose correction. Or Yes, the new group can be in another area of the wafer requiring dose correction. In the process described above, the selected scan line for each group is repeated until the area requiring dose correction has been completed. Add each group The number of scan lines is until the minimum dose correction divided by the number of scan lines η is less than or equal to the required dose correction. When the wafer is scanned using this variable spatial frequency dose correction rule, Faraday Cup 38 To the updated version of the dose map (as shown in Figure 2). If the current scan line group is determined to be the last group to be corrected in step 260, the process returns to step 206 (Figure 4). In step 206, a further Is the required dose correction required? In this way, the process verifies that the dose correction rule for the variable spatial frequency has reached the required dose map. Alternatively, the implantation is deemed to have been completed after step 260 without further dose map confirmation. This disclosure The technology has the effect of reducing the spatial frequency of the scanning line. The spatial frequency is related to the standard spatial frequency, and has a reduction in the dose correction that can be applied to the wafer. Through the change in the number of scanning lines per scanning line group, The standard spatial frequency of the scan line and the dose correction can be adjusted to provide the required dose correction. Therefore, a relatively low scan line spatial frequency can be used to obtain a smaller amount of dose correction. Conversely, a scan line of 20 (please read Note on the back, please fill in this page again) — Order -------- The paper size is applicable to China National Standard (CNS) A4 specification (210 X 297 mm) 1222099 A7 _____B7____ 5. Description of the Invention (l /) A relatively high spatial frequency is used to obtain a larger dose correction. At the end of implantation, 'variable spatial frequency dose correction rules can be used to Dose correction. Dose correction can be done on selected areas of the wafer or on the entire wafer surface. In another embodiment, 'control of scan line spatial frequency can be used to complete low-dose implantation. When using standard This method can be used when the scan protocol's single transcribing wafer 'causes the dose to exceed the prescribed dose. Control of the spatial frequency of the scan line can thus provide a technique for low implantation doses. In the example of Fig. 5, the maximum number n_max of a set of internal scan lines is fixed. In another embodiment, the maximum number of scan lines in a set of scan lines can be adjusted or programmed according to the ion beam height in the mechanical transmission direction. In relatively high ion beams, the maximum number of scan lines n_max in a set of scan lines can be increased, thereby increasing the range of possible dose corrections. Although the presentation of the preferred embodiment of the present invention has been described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope as defined by the appended claims. 21 ―The paper size applies to the Chinese National Standard (CNS) A4 (210 X 297 mm) 15b -------------- 41 ^ Packing -------- Order ----- ---- (Please read the notes on the back before filling this page)