519701 7449twf.doc/012 A7 B7 五、發明說明（/ ) (請先閱讀背面之注意事項再填寫本頁) 本發明是有關於一種疊合標記（Overlay Mark)結構及 其量測應用’且特別是有關於一種可防止化學機械硏磨 (Chemical Mechanical Polishing)製程破壞之疊合標記結 構，由於本質上優於傳統之設計，並配合X、Y方向同時 的量測’因此可提高量測疊合誤差（0verlay Error)之精確 度，其係利用本發明所提出之疊合標記來完成。 通常決疋一晶圓之微影製程（Photolithography Process) 成敗的因素’除了關鍵尺寸（Critical Dimension，CD)之控 制外’另一重要者即爲對準精確度（Alignment Accuracy， AA)。因此’對準精確度之量測，即疊合誤差之量測是半 導體製程中重要的一環，而疊合標記就是用來量測疊合誤 Μ之X具’其係用來判斷微影製程後光阻層之圖案與晶片 上前一晶圓層之間是否有精確的對準。 第1圖所繪示爲一晶圓之上視圖，並繪出疊合標記之 位置。 經濟部智慧財產局員工消費合作社印製 請參照第1圖，在晶圓（Wafer)lOO製作完成之後，即 可沿著切割道1〇4切割晶圓100,以形成數個晶片（Chip) 或晶粒(Die)102。通常疊合標記1〇6係配置在每一晶片102 周緣之四個角落的切割道104上，用以量測製程步驟中每 一晶片上之光阻層圖案是否與晶片上前一晶圓層對準。 第2圖爲第1圖之直線M，的剖面圖，其顯示習知之 疊合標記與相鄰之晶片的一部分的結構，此疊合標記係應 用於一金屬內連線製程中，且其製造過程說明如下。 請參照第2圖，在基底200中已形成有金屬層202， 3 本紙張尺度適用中國國家標準（CNS)A4規格（21〇 χ 297公釐） 519701 7449twf. doc/012 A7 B7 五、發明說明（>) (請先閱讀背面之注意事項再填寫本頁) 且在基底200上形成有一介電層205，而在介電層205中 形成有介層洞（Via Hole)206與溝渠207。接著在介電層205 上沈積一金屬層2〇1，以完全塡滿寬度較窄之介層洞206， 但僅覆蓋住溝渠207之表面，之後以化學機械硏磨法除去 介層洞206與溝渠207外之金屬層204,暴露出介電層205， 意即以介電層205爲硏磨終止層（Stop Layer)，以在介層洞 206中形成插塞。接著，在介電層205上沈積金屬層208， 並塡入溝渠207中，此時由於溝渠207之寬度夠寬，所以 在溝渠207上方之金屬層208上亦形成有溝槽211。 之後，經過光阻塗佈、曝光及微影等製程以在金屬層 208上形成圖案化之一光阻層210，其係暴露出金屬層208 中欲形成導線之區域，而在切割道中形成之光阻圖案21〇a 與溝槽211即合爲用以量測對準精確度之疊合標記212。 第3圖所繪示爲習知之疊合標記結構的上視圖。 經濟部智慧財產局員工消費合作社印製 請同時參照第2圖與第3圖，第3圖係爲第2圖中由 溝槽211與光阻圖案210a所組成之疊合標記212的上視 圖。習知之疊合標記212係由一外圍標記（Outer Mark)302 與一內部標記(Inner Mark)304所組成，其中外圍標記302 係由圍成矩形的四個第2圖中之溝槽211所組成，而內部 標記304係由圍成另一矩形的四個第2圖中之條狀光阻圖 案210a所組成，且外圍標記302係包圍住內部標記304。 而此疊合標記212係配置在每一晶片周圍四個角落之切割 道上，用以量測當層光阻層是否與晶片上前一層精確對 準。 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 1 經濟部智慧財產局員工消費合作社印製 519701 7449twf.doc/012 A7 -- B7 五、發明說明（$ ) 第4圖所繪示爲第3圖之直線ΙΙ-ΙΓ的剖面圖。 請同時參照第3圖與第4圖，第4圖中之溝槽211係 對應於第3圖之外圍標記302，而第4圖之光阻圖案210a 係對應於第3圖之內部標記304。 第5圖所繪示爲由第4圖中之疊合標記所得之訊號波 形。 請同時參照第4圖與第5圖，第4圖之溝槽211的波 峰訊號爲第5圖中之502a、502b，而光阻圖案210a之波 峰訊5虎爲弟5圖中之506a、506b。利用習知暨合標記重測 對準精確度之方法，係先讀取溝槽211之波峰訊號502a、 502b，並取其中間値504，再讀取光阻圖案210a之波峰訊 號1〇6a、506b，並取其中間値508，然後計算中間値504 與中間値508之差異，即爲疊合誤差。倘若此疊合誤差大 於可接受之偏差値，則表示該次光阻層圖案與晶片間之對 準並未達到所要求之精確度，而必須將此光阻層去除，並 重新再做一次微影製程，直到疊合誤差之値小於可接受之 偏差値爲止。 然而，習知之疊合標記的外圍標記在歷經化學機械硏 磨製程後，因硏磨率的變異(Polishing Rate Deviation)、硏 漿（Slurry)的腐蝕、晶圓上圖案之密度、以及晶圓中心與邊 緣之硏磨差異等等許多因素，會影響疊合標記之品質，甚 至損壞疊合標記。再者，金屬層本質上的晶粒（Grain)亦是 影響量測精確度的重要因素，因爲若晶粒之顆粒太大會造 成量測之雜訊。上述兩者均會致使所量測到之波峰訊號之 --------------------訂--------- 線f (請先閱讀背面之注意事項再填寫本頁) 1 本紙張尺度適用中國國家標準（CNS)A4規公:ίΤ 經濟部智慧財產局員工消費合作社印製 519701 7449twf.doc/012 A7 B7 五、發明說明（</) 波形（Signal Profile)不佳，而嚴重影響到量測之結果，甚 至無法量測，這是因爲習知之疊合標記之外圍標記302(即 溝槽211部分)相距較遠，意即溝槽211分佈之密度較低結 構較爲鬆散，因此較無法抵抗化學機械硏磨製程之磨損。 尤其對於金屬介層窗形成後之化學機械硏磨，特別是銅金 屬雙重金屬鑲嵌，其疊合標記之完整性對於後續製程具有 舉足輕重之影響，這是因爲銅金屬本身之穩定性、對抗硏 漿腐蝕性以及擴散等問題，都比其他金屬例如鎢更爲嚴 重。 第6圖所示，其繪示爲使用習知之疊合標記量測疊合 誤差之方法。 請參照第6圖，使用習知之疊合標記量測疊合誤差時’ 係沿著疊合標記212之一 X方向直線310量測一 X方向 偏移量，再沿著疊合標記212之一 Y方向直線312量測一 Y方向偏移量。當所有切割道上被指定的疊合標記212皆 以此方式量測之後，即可利用X方向與Y方向兩組偏移 量計算出當層光阻層之圖案與晶片上前一晶圓層之間是否 有精確對準。 然而，由一個習知疊合標記212僅能量測出一個X方 向偏移量與一個Y方向偏移量，倘若外圍標記3〇2在化學 機械硏磨製程中遭到破壞，而無法量測到X方向或Y方 向偏移量時，將無法正確的判斷出其對準精確度。 因此，本發明的目的就是在提供一種疊合標記之結構 與製造方法，其可以減小疊合標記被化學機械硏磨製程破 6 本纸張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） -------------------訂---------線 (請先閱讀背面之注意事項再填寫本頁) 519701 7449twf.doc/012 A7 B7 五、發明說明（r) 壞之機率。 (請先閱讀背面之注意事項再填寫本頁) 本發明的另一目的是提供一種疊合標記結構及其量測 與分析方法，以提高所量測之疊合誤差的準確度。 本發明提出一種疊合標記結構，其係包含一外圍標記 與一內部標記，其中外圍標記係圍出一封閉十字形區域’ 且此封閉十字形區域具有二中心軸線；內部標記係由四個 長條狀圖案組成，此四個長條狀圖案沿著二中心軸線排 列，且四個長條狀圖案分別以四個方向由十字形區域之中 心部分往外延伸。 線φ-· 本發明提出一種量測疊合誤差之方法5此方法係首先 提供一疊合標記，此疊合標記係由一外圍標記與一內部標 記所組成，其中此外圍標記係圍出具有二中心軸線之一封 閉十字形區域，而內部標記係沿著二中心軸線排列，並由 十字形區域之中心部分向外延伸之二個X方向長條狀圖案 與二個γ方向長條狀圖案。接著9沿著疊合標記之一 χ/γ 方向直線量測一 x/γ方向偏移量，其中Χ/γ方向直線切 過封閉十字形區域之一 Υ/Χ方向延伸區以及其中之一 Υ/Χ 方向長條狀圖案。 經濟部智慧財產局員工消費合作社印製 本發明又提出一種分析疊合誤差因子的方法’此方法 係首先提供一疊合標記，此疊合標記係由一外圍標記與一 內部標記所組成，其中此外圍標記係圍出具有二中心軸線 之一封閉十字形區域，而內部標記係沿著二中心軸線排 列，並由十字形區域之中心部分向外延伸之二個X方向長 條狀圖案與二個Υ方向長條狀圖案。接著，沿著疊合標記 7 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 519701 7449twf. doc/012 A7 B7 五、發明說明（么） (請先閱讀背面之注意事項再填寫本頁> 之一'第一^ X/Y方向直線量測一*第一* X/Y方向偏移量，其 中第一 X/Y方向直線切過封閉十字形區域之其中一 Y/X 方向延伸區以及其中之一 Y/X方向長條狀圖案，並且沿著 疊合標記之一第二X/Y方向直線量測一第二X/Y方向偏 移量5其中第二X/Y方向直線切過封閉十字形區域之另一 Y/X方向延伸區以及另一 Y/X方向長條狀圖案。之後由第 一 X/Y方向偏移量與第二X/Y方向偏移量（共四個）求得數 種疊合誤差因子，其中數種疊合誤差因子包含平移誤差與 因光罩位置造成的標軸旋轉(Reticle Rotation，RR)誤差。 本發明之疊合標記係爲一強化之結構，對於抵抗在金 屬內連線製程之化學機械硏磨製程對外圍標記之損壞特別 具有成效，因此可降低被化學機械硏磨製程破壞之機率， 其原因將在實施例中說明。 本發明之疊合標記之內部標記係由當層光阻層所定 義，一般其訊號均相當良好，所以不必顧忌單一截面之量 測由二個標記成爲只有一個標記，會造成量測的不穩定之 原因，反而會因單一組標記其X、Y方向各二點，而爲習 知疊合標記的二倍，增加了取樣及計算精確度。 經濟部智慧財產局員工消費合作社印製 另外，使用本發明之疊合標記結構及量測方法時，可 提高量測出之疊合誤差的準確度，其原因亦將在實施例中 說明。 再者，本發明只需要一個疊合標記即可求出標軸旋轉 誤差，其原因亦將在實施例中說明。 爲讓本發明之上述和其他目的、特徵、和優點能更明 8 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 519701 7449twf.doc/012 五、發明說明（7 ) 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： (請先閱讀背面之注意事項再填寫本頁) 第1圖爲一晶圓之上視圖，並繪出其上疊合標記之位 置， 第2圖爲第1圖之直線Ι-Γ的剖面圖，其顯示習知之 疊合標記與相鄰之晶片的一部分的結構，此疊合標記係應 用於一金屬內連線製程中； 第3圖爲習知之疊合標記結構的上視圖； 第4圖爲第3圖之疊合標記之直線ΙΙ-ΙΓ的剖面圖； 第5圖爲由第4圖之疊合標記所量測得之訊號波形； 第6圖爲使用習知之疊合標記時之疊合誤差量測方 法； 第7圖爲依照本發明一較佳實施例之疊合標記結構的 上視圖； 第8圖爲第7圖之疊合標之直線ΙΙΙ-ΙΙΓ的剖面圖； 經濟部智慧財產局員工消費合作社印製 第9圖爲由第8圖之疊合標記所量測得之訊號波形； 第10圖爲依照本發明一較佳實施例之疊合誤差的量 測方法； 第11圖爲圖解本發明單一組疊合標記可求出標軸旋 轉誤差之示意圖。 第12圖爲圖解習知疊合標記無法以單一組求出標軸 旋轉誤差，而必須藉由不同方爲之多組標記才可計算得到 之示意圖。 9 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 519701 7449twf.doc/012 A7 137 五、發明說明（s ) 圖式之標號說明： 10 0 :晶圓 102 :晶片或晶粒 (請先閱讀背面之注意事項再填寫本頁) 104 :切割道 106 :疊合標記 200、800 :基底 202、208、808 :金屬層 204、804 :金屬層或插塞 205 :介電層 206 :介層洞 207、807 :溝渠 210 :光阻層 210a、810a :切割道上之光阻圖案 211、 811 :溝槽 212、 700 :疊合標記 302、702 :外圍標記 304、704 :內部標記 310、710、712 : X 方向直線 312、714、716 : Y 方向直線 經濟部智慧財產局員工消費合作社印製 502a、502b > 506a、506b、902a、902b、904 ：波峰 訊號 504、508、906、908 :中間値 706、708 :中心軸線 實施例 10 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 經濟部智慧財產局員工消費合作社印製 519701 7449twf.doc/012 A7 B7 五、發明說明（气） 第7圖所示，其繪示爲依照本發明一較佳實施例之疊 合標記結構的上視圖。 請參照第7圖，本發明之疊合標記700係由一外圍標 記702與一內部標記704所組成，其中外圍標記702係圍 出一封閉十字形區域，其具有二中心軸線710、712。內部 標記704係由四個長條狀圖案所組成，這四個長條狀圖案 係沿著二中心軸線710、712排列，並分別以四個方向由 十字形區域之中心部分向外延伸，此內部標記704之四個 長條狀圖案之間彼此不連接，且與外圍之外圍標記702亦 不連接。 第8圖係繪示爲第7圖之疊合標記700之直線ΙΙΙ-ΙΙΓ 的剖面圖。 請同時參照第7圖與第8圖，第7圖中之外圍標記702 係對應於第8圖之溝槽811，而第7圖中之內部標記704 係對應於第8圖之光阻層圖案810a。 請參照第8圖，疊合標記700之製造方法如下：首先 提供已形成有二溝渠807之基底800，此二溝渠807係爲 對應於外圍標記702之十字環狀溝渠的一部分。接著，形 成一共形金屬層804,其材質係爲適用於插塞之材質例如 爲鎢或銅。之後，以化學機械硏磨製程去除溝渠807外之 共形金屬層804，而暴露出基底800。然後在基底800上 形成一金屬層808，此時由於二溝渠807之寬度足夠寬， 使得二溝渠807上方之金屬層808上形成有二溝槽811 ’ 其中二溝槽811係爲外圍標記702之一部分。之後，在金 11 本纸張尺度適用中國國家標準（CNS)A4規格（210 x 297公釐） --------------------訂---------線 (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 519701 7449twf.doc/012 Λ7 B7 五、發明說明（p) 屬層808上形成圖案化之一光阻層810a，此光阻層810a 係位在兩溝槽811中間之部分的金屬層808上，且係爲內 部標記704之一部分。 第9圖所示，其繪示爲由第8圖之疊合標記所量測得 之訊號波形。 請同時參照第8圖與第9圖，第8圖之溝槽811之波 峰訊號爲第9圖之902a、902b，且第8圖之光阻圖案810a 之波峰訊號爲第9圖之904。本實施例在計算疊合誤差時’ 係先讀取溝槽811之波峰訊號902a、902b，並取其中間値 906，再讀取光阻圖案810a之單一波峰訊號904之中間値 908 5然後計算中間値906與中間値908之差異，即爲疊 合誤差。倘若此疊合誤差大於可接受之偏差値5則表示該 次光阻層圖案與晶片之對準並未達到所要求之精確度，而 必須將此光阻層去除，重新再做一次微影製程，直到疊合 誤差之値小於可接受之偏差値爲止。 與習知矩形疊合標記相較之下，本發明所形成之十字 形疊合標記對於化學機械硏磨之抵抗能力較佳。這是因爲 本發明之疊合標記圖形中溝渠分佈之密度較高，因此對於 化學機械硏磨之抵抗能力較佳。 第10圖所不，其繪不爲依照本發明一較佳實施例之 疊合誤差的量測方法。 請參照第10圖，本實施例之疊合誤差的量測法，係 沿著第一 X方向直線710量測第一 X方向偏移量，此第 一 X方向直線710切過此外圍標記702之一 Y方向延伸 12 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） ------------·!丨-—訂--------線 (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 519701 7449twf.doc/012 A7 B7 五、發明說明（丨丨） 區以及內部標記704之一 Y方向長條狀圖案。然後沿著第 二X方向直線712量測第二X方向偏移量，此第二x方 向直線712切過外圍標記702之另一 Y方向延伸區以及內 部標記7〇4之另一 Y方向長條狀圖案。然後沿著第一 Y 方向直線714量測第一 Y方向偏移量，此第一 γ方向直 線714切過外圍標記702之一 X方向延伸區以及內部標記 704之一 X方向長條狀圖案。然後沿著第二Υ方向直線716 量測第二Y方向偏移量9此第二Y方向直線716切過外 圍標記702之另一 X方向延伸區以及內部標記704之另一 X方向長條狀圖案。之後，由第一 Y方向偏移量與第二Y 方向偏移求得一 γ方向平均偏移量，並由第一 x方向偏 移量與第二X方向偏移求得一 X方向平均偏移量。 本發明之疊合標記之量測方法，對於每一疊合標記在 X或γ方向上皆可量測兩個偏移量’而習知之疊合標§己在 X或Y方向上僅能讀取一個偏移量，所以就統計觀點而言’ 本發明之對準精確度的量測較爲精確。再者，倘若本發明 之疊合標記於化學機械硏磨時遭到局部的破壞，僅需量測 一個X方向偏移量5或者一個γ方向偏移量，就可以兀 成對準精確度之量測。反之，由於習知之疊合標記在Χ或 Υ方向上僅能讀取一個偏移量，所以當部分之疊合標記遭 受化學機械硏磨之破壞時，極可能無法完成對準精確度之 量測。 第11圖所示，其繪示爲圖解本發明單一組疊合標記 可求出標軸旋轉誤差之示意圖。 13 _____________ ' 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） —-------------------訂---------線 (請先閱讀背面之注意事項再填寫本頁) 519701 7449twf.doc/012 A7 B7 五、發明說明（/>) 請參照第Π _，利用本發明之疊合標記7〇〇以分析 暨合誤差因子的方法，係利用如第7圖所示之疊合誤差的 麗測方法9 f口者疊合標記7〇〇之第一 χ/γ方向直線7丨〇/7 i 4 量測出第一 X/Y方向偏移量，並沿著疊合標記7〇〇之第二 X/Y方向直線712/716量測出第二χ/γ方向偏移量。之後 由第一/二X方向偏移量之平均値Ax即可求出X方向平移 誤差’由第一/一 Y方向偏移量之平均値Αγ即可求出γ方 向平移誤差，且由第一 X方向偏移量與第二X方向偏移 量各自與Αχ之差異（或再加上第一 γ方向偏移量與第二γ 方向偏移量各自與Αγ之差異）即可求出標軸旋轉誤差。因 此，本發明之疊合標記僅需一個疊合標記即可求出標軸旋 轉誤差。 第12圖所示，其繪示爲圖解習知疊合標記無法以單 一組求出標軸旋轉誤差，而必須藉由不同方爲之多組標記 才可計算得到之示意圖。 請參照第12圖，然而以習知之疊合標記212分析疊 合誤差因子’由於量測機台對於疊合標記212之量測係以 一固定寬度之區域量測，因此僅能由X方向直線310量測 出一 X方向偏移量，由Υ方向量測出一 Υ方向直線312 量測出一 Υ方向偏移量。然而，由一 X方向偏移量與一 Υ 方向偏移量僅能求出平移誤差，而無法求得標軸旋轉誤 差。因此，倘若要以習知之疊合標記212求出標軸旋轉誤 差，必須再量測另一疊合標記之X方向偏移量與Υ方向 偏移量，利用兩個X方向偏移量與兩個Υ方向偏移量， 14 ------------------訂---------線· (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產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（210 X 297公釐） 519701 7449twf.doc/012 A7 五、發明說明（/?) 才能求得標軸旋轉誤差。 綜合以上所述，本發明具有下列優點： 1. 本發明之疊合標記係爲一強化之結構，對於抵抗在 金屬內連線製程之化學機械硏磨特別具有成效，因此可降 低被化學機械硏磨製程破壞之機率。 2. 使用本發明之疊合標記結構及量測方法時，可提高 量測出之疊合誤差的準確度。 3. 本發明只需要一個疊合標記即可求出標軸旋轉誤 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，當可作些許之更動與潤飾，因此本發明之保 護範圍當視後附之申請專利範圍所界定者爲準。 (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產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（210 X 297公釐）519701 7449twf.doc / 012 A7 B7 V. Description of the invention (/) (Please read the precautions on the back before filling out this page) The present invention is related to an overlay mark structure and its measurement application 'and is particularly The invention relates to a superimposed mark structure which can prevent the destruction of the chemical mechanical polishing process. Since it is substantially better than the traditional design, and it is used in conjunction with simultaneous measurement in the X and Y directions, the measurement superposition can be improved. The accuracy of the error (0verlay Error) is achieved by using the superposed mark proposed by the present invention. Usually, the factor that determines the success or failure of the photolithography process of a wafer, in addition to the control of critical dimension (CD), is another important issue: alignment accuracy (AA). Therefore, the measurement of the alignment accuracy, that is, the measurement of the stacking error, is an important part of the semiconductor process, and the stacking mark is an X tool for measuring the stacking error M. It is used to judge the lithography process. Is there a precise alignment between the pattern of the rear photoresist layer and the previous wafer layer on the wafer? Figure 1 shows the top view of a wafer and the position of the overlay marks. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, please refer to Figure 1. After the wafer 100 is finished, the wafer 100 can be cut along the scribe line 104 to form several chips or chips. Die (Die) 102. Generally, the superimposed marks 106 are arranged on the scribe lines 104 at the four corners of the periphery of each wafer 102 to measure whether the photoresist layer pattern on each wafer in the process step is the same as the previous wafer layer on the wafer. alignment. FIG. 2 is a cross-sectional view of the line M in FIG. 1, which shows the structure of a conventional superimposed mark and a part of an adjacent wafer. The superposed mark is used in a metal interconnection process, and its manufacturing The process is explained below. Please refer to Figure 2. A metal layer 202 has been formed in the substrate 200. 3 This paper size is in accordance with the Chinese National Standard (CNS) A4 (21〇χ 297 mm) 519701 7449twf. Doc / 012 A7 B7 V. Description of the invention (≫) (Please read the notes on the back before filling this page). A dielectric layer 205 is formed on the substrate 200, and a via hole 206 and a trench 207 are formed in the dielectric layer 205. Next, a metal layer 201 is deposited on the dielectric layer 205 so as to completely fill the narrow via hole 206, but only covers the surface of the trench 207, and then removes the via holes 206 and 206 by chemical mechanical honing. The metal layer 204 outside the trench 207 exposes the dielectric layer 205, which means that the dielectric layer 205 is used as a honing stop layer to form a plug in the dielectric hole 206. Next, a metal layer 208 is deposited on the dielectric layer 205 and is inserted into the trench 207. At this time, since the width of the trench 207 is wide enough, a trench 211 is also formed on the metal layer 208 above the trench 207. Then, a photoresist layer 210 is formed on the metal layer 208 through processes such as photoresist coating, exposure, and lithography, which expose the areas of the metal layer 208 where wires are to be formed, and are formed in the scribe lines. The photoresist pattern 21a and the groove 211 are combined into a superposed mark 212 for measuring alignment accuracy. FIG. 3 is a top view of a conventional superimposed marker structure. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economics Please refer to Figures 2 and 3 at the same time. Figure 3 is a top view of the superimposed mark 212 composed of the groove 211 and the photoresist pattern 210a in Figure 2. The conventional superimposed mark 212 is composed of an outer mark 302 and an inner mark 304. The outer mark 302 is composed of four grooves 211 in the second figure enclosed in a rectangle. The inner mark 304 is composed of four strip-shaped photoresist patterns 210a in the second figure enclosed in another rectangle, and the outer mark 302 surrounds the inner mark 304. The superimposed mark 212 is arranged on the scribe lines at four corners around each wafer to measure whether the current photoresist layer is accurately aligned with the previous layer on the wafer. This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 1 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 519701 7449twf.doc / 012 A7-B7 V. Description of Invention ($) Figure 4 It is shown as a cross-sectional view along the line III-III in FIG. 3. Please refer to FIG. 3 and FIG. 4 at the same time. The groove 211 in FIG. 4 corresponds to the peripheral mark 302 in FIG. 3, and the photoresist pattern 210a in FIG. 4 corresponds to the inner mark 304 in FIG. Figure 5 shows the signal waveform obtained from the superimposed marks in Figure 4. Please refer to FIG. 4 and FIG. 5 at the same time. The peak signal of the groove 211 in FIG. 4 is 502a and 502b in FIG. 5, and the peak signal of the photoresist pattern 210a is 5 and 506a and 506b in FIG. 5. . The method of re-testing the alignment accuracy using the conventional mark is to first read the peak signals 502a and 502b of the trench 211, take the middle 504, and then read the peak signals 106a of the photoresist pattern 210a, 506b, and take the middle 値 508, and then calculate the difference between the middle 値 504 and the middle 値 508, which is the superposition error. If the overlap error is greater than the acceptable deviation 値, it means that the alignment between the pattern of the photoresist layer and the wafer has not reached the required accuracy, and the photoresist layer must be removed and re-micronized. Process until the overlap error is less than the acceptable deviation. However, the peripheral marks of the conventional superimposed marks have undergone a chemical mechanical honing process, due to variations in the polishing rate (Polishing Rate Deviation), corrosion of the slurry (Slurry), the density of the pattern on the wafer, and the wafer center. Many factors, such as the difference in honing from the edge, will affect the quality of the superimposed mark and even damage the superimposed mark. In addition, the grain of the metal layer (Grain) is also an important factor affecting the accuracy of the measurement, because if the grain of the crystal is too large, it will cause measurement noise. Both of the above will cause the measured peak signal of the -------------------- order --------- line f (please read first Note on the back, please fill out this page again) 1 This paper size is applicable to Chinese National Standard (CNS) A4 regulations: ίΤ Printed by the Employees ’Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 519701 7449twf.doc / 012 A7 B7 V. Description of the invention (< // ) The waveform (Signal Profile) is not good, and it seriously affects the measurement results, and it is even impossible to measure. This is because the outer mark 302 (ie, the groove 211) of the conventional superimposed mark is far away, which means the groove. The lower density of the 211 distribution is looser and therefore less resistant to abrasion in the CMP process. Especially for the chemical-mechanical honing after the formation of the metal interlayer window, especially the copper-metal dual-metal inlay, the integrity of the superimposed marks has a significant impact on the subsequent process, because of the stability of the copper metal itself and its resistance to slurry. Corrosion and diffusion problems are more serious than other metals such as tungsten. Fig. 6 shows a method for measuring the overlay error using a conventional overlay mark. Please refer to Fig. 6. When the overlap error is measured using the conventional overlay mark, the straight line 310 along the X direction of one of the overlay marks 212 is used to measure an X direction offset, and then one of the overlay marks 212 is measured. The Y-direction straight line 312 measures a Y-direction offset. After all the superimposed marks 212 on the dicing track are measured in this way, the two directions of the X direction and Y direction can be used to calculate the pattern of the photoresist layer and the previous wafer layer on the wafer. Whether there is precise alignment between them. However, only one X-direction offset and one Y-direction offset can be measured by a conventional superimposed mark 212. If the peripheral mark 30 is damaged during the chemical mechanical honing process, it cannot be measured. When the X direction or Y direction is offset, the alignment accuracy cannot be accurately determined. Therefore, the object of the present invention is to provide a structure and a manufacturing method of superimposed marks, which can reduce the superimposed marks being broken by the chemical mechanical honing process. 6 The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) ------------------- Order --------- line (please read the precautions on the back before filling this page) 519701 7449twf. doc / 012 A7 B7 5. Description of the invention (r) Probability of bad. (Please read the precautions on the back before filling this page) Another object of the present invention is to provide a superimposed marker structure and its measurement and analysis method to improve the accuracy of the superimposed error measured. The present invention proposes a superimposed mark structure, which includes a peripheral mark and an internal mark, wherein the peripheral mark surrounds a closed cross-shaped area ', and the closed cross-shaped area has two central axes; the internal mark is composed of four long The four strip-shaped patterns are arranged along two central axes, and the four strip-shaped patterns respectively extend outward from the central portion of the cross-shaped area in four directions. Line φ- · The present invention proposes a method for measuring overlap error. 5 This method first provides a superimposed mark. The superposed mark is composed of an outer mark and an inner mark. The outer mark is surrounded by One of the two central axes encloses the cross-shaped area, and the internal marks are arranged along the two central axes and two X-direction strip patterns and two γ-direction strip patterns extend outward from the central portion of the cross-shaped region. . Next, 9 measure an x / γ offset in a straight line along the χ / γ direction of one of the superimposed marks, where the X / γ direction cuts straight through one of the closed cross-shaped areas Υ / χ direction extension area and one of them Υ / × Long stripe pattern. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs The present invention also proposes a method for analyzing superposition error factors. This method first provides a superposition mark, which is composed of a peripheral mark and an inner mark, where The outer markings enclose a closed cross-shaped area with one of the two central axes, and the inner markings are arranged along the two central axes and two X-directional strip patterns extending outwardly from the central portion of the cross-shaped area and two A long stripe pattern in the Υ direction. Next, along the superimposed mark 7 this paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 mm) 519701 7449twf. Doc / 012 A7 B7 V. Description of the invention (?) (Please read the notes on the back first Fill in this page again> One of the 'first ^ X / Y direction straight line measurement one * first * X / Y direction offset, where the first X / Y direction straight cuts through one of the closed cross-shaped areas Y / X direction extension area and one of the Y / X direction stripe patterns, and a second X / Y direction offset is measured straight along a second X / Y direction of the superimposed mark 5 of which the second X The / Y direction cuts straight through another Y / X direction extension area of the closed cross-shaped area and another Y / X direction strip pattern. Then, the first X / Y direction offset is offset from the second X / Y direction. The shift amount (total of four) is used to obtain several kinds of superimposition error factors, among which several kinds of superimposition error factors include translation errors and Reticle Rotation (RR) errors caused by the position of the mask. The superposition marks of the present invention It is a reinforced structure, which is resistant to damage to the peripheral marks by the chemical mechanical honing process of the metal interconnect process. It is particularly effective, so it can reduce the probability of being damaged by the chemical mechanical honing process. The reason will be explained in the embodiment. The internal mark of the superimposed mark of the present invention is defined by the current photoresist layer, and generally its signals are equivalent. Good, so there is no need to worry about the measurement of a single cross-section changes from two marks to only one mark, which will cause the instability of the measurement. Instead, a single group will mark its two points in the X and Y directions, which is a superposition of knowledge The marking is doubled, which increases the accuracy of sampling and calculation. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy The reason will also be explained in the embodiment. Furthermore, the present invention only needs a superimposed mark to obtain the axis rotation error, and the reason will be explained in the embodiment. In order to make the above and other aspects of the present invention Purpose, characteristics, and advantages can be made clearer 8 The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 519701 7449twf.doc / 012 5. Description of the invention (7) It is easy to understand. The following is a detailed description of a preferred embodiment and the accompanying drawings, which are described in detail as follows: Brief description of the drawings: (Please read the precautions on the back before filling this page) Figure 1 is a wafer The top view, and the position of the superimposed mark on it is plotted. FIG. 2 is a cross-sectional view of the straight line I-Γ of FIG. 1, which shows the structure of a conventional superposed mark and a part of an adjacent wafer. The composite mark is used in a metal interconnection process; Figure 3 is a top view of a conventional stacked mark structure; Figure 4 is a cross-sectional view of the straight line ΙΙ-ΙΓ of the stacked mark of Figure 3; Figure 5 Figure 4 is the signal waveform measured by the superimposed mark in Figure 4. Figure 6 is the superimposed error measurement method when the conventional superimposed mark is used. Figure 7 is a superimposed method according to a preferred embodiment of the present invention. Top view of the composite mark structure; Figure 8 is a cross-sectional view of the superimposed straight line ΙΙΙ-ΙΙΓ of Figure 7; printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs; Figure 9 is shown by the superimposed mark of Figure 8 Measured signal waveform; FIG. 10 is a superposition according to a preferred embodiment of the present invention Difference measurement method; graph 11 illustrates a single set of the present invention can be determined scale marks overlapping error of the rotation shaft schematic. Fig. 12 is a schematic diagram illustrating that conventional superimposed markers cannot be used to calculate the rotation error of the axis in a single group, but must be calculated by different sets of markers. 9 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 519701 7449twf.doc / 012 A7 137 V. Description of the invention (s) Symbol description of the drawing: 10 0: Wafer 102: Wafer or Die (please read the precautions on the back before filling this page) 104: Cutting track 106: Superimposed mark 200, 800: Base 202, 208, 808: Metal layer 204, 804: Metal layer or plug 205: Dielectric Layers 206: vias 207, 807: trenches 210: photoresist layers 210a, 810a: photoresist patterns 211, 811 on scribe lines: trenches 212, 700: superimposed marks 302, 702: peripheral marks 304, 704: internal Marks 310, 710, and 712: straight lines in the X direction 312, 714, 716: straight lines in the Y direction Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy 502a, 502b > 506a, 506b, 902a, 902b, 904: Crest signals 504, 508, 906, 908: Middle 値 706, 708: Central axis Example 10 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 519701 7449twf.doc / 012 A7 B7 V. Description of Invention (Gas) Figure 7 shows Which is in accordance with the present invention shows a top view of the stack of bonded mark structure according to a preferred embodiment. Referring to FIG. 7, the superimposed mark 700 of the present invention is composed of an outer mark 702 and an inner mark 704, wherein the outer mark 702 encloses a closed cross-shaped area having two central axes 710, 712. The internal mark 704 is composed of four strip-shaped patterns. These four strip-shaped patterns are arranged along the two central axes 710 and 712 and extend outward from the central portion of the cross-shaped area in four directions. The four strip-shaped patterns of the inner mark 704 are not connected to each other, and are not connected to the outer peripheral mark 702. FIG. 8 is a cross-sectional view of the line ΙΙΙ-ΙΙΓ of the superposed mark 700 of FIG. 7. Please refer to FIGS. 7 and 8 at the same time. The peripheral mark 702 in FIG. 7 corresponds to the groove 811 in FIG. 8, and the internal mark 704 in FIG. 7 corresponds to the photoresist layer pattern in FIG. 8. 810a. Referring to FIG. 8, the manufacturing method of the superimposed mark 700 is as follows: First, a base 800 having a second trench 807 formed is provided. The second trench 807 is a part of a cross-shaped circular trench corresponding to the peripheral mark 702. Next, a conformal metal layer 804 is formed, and the material of the conformal metal layer 804 is, for example, tungsten or copper. Thereafter, the conformal metal layer 804 outside the trench 807 is removed by a chemical mechanical honing process, and the substrate 800 is exposed. Then, a metal layer 808 is formed on the substrate 800. At this time, because the width of the second trench 807 is wide enough, two trenches 811 ′ are formed on the metal layer 808 above the second trench 807. portion. After that, the Chinese National Standard (CNS) A4 specification (210 x 297 mm) was applied to the gold 11 paper size -------------------- Order ---- ----- Line (Please read the notes on the back before filling this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 519701 7449twf.doc / 012 Λ7 B7 V. Description of the invention (p) Patterns on the layer 808 A photoresist layer 810a is formed. The photoresist layer 810a is located on the metal layer 808 in the middle of the two trenches 811, and is a part of the internal mark 704. As shown in FIG. 9, it is a signal waveform measured by the superimposed mark in FIG. 8. Please refer to FIG. 8 and FIG. 9 at the same time. The peak signal of the trench 811 in FIG. 8 is 902a and 902b in FIG. 9 and the peak signal of the photoresist pattern 810a in FIG. 8 is 904 in FIG. 9. In the calculation of the superposition error in this embodiment, the peak signals 902a and 902b of the groove 811 are read first, and the middle 値 906 is taken, and then the middle 値 908 5 of the single peak signal 904 of the photoresist pattern 810a is calculated. The difference between intermediate 値 906 and intermediate 値 908 is the superposition error. If the overlap error is greater than the acceptable deviation 値 5, it means that the alignment of the pattern of the photoresist layer with the wafer does not reach the required accuracy, and the photoresist layer must be removed and the lithography process performed again. Until the overlap error 叠 is less than the acceptable deviation 値. Compared with the conventional rectangular superposed marks, the cross-shaped superposed marks formed by the present invention have better resistance to chemical mechanical honing. This is because the density of the trench distribution in the superimposed mark pattern of the present invention is relatively high, so the resistance to chemical mechanical honing is better. What is shown in FIG. 10 is not a method for measuring a superposition error according to a preferred embodiment of the present invention. Referring to FIG. 10, the measurement method of the superposition error in this embodiment measures the first X-direction offset along the first X-direction straight line 710, and the first X-direction straight line 710 cuts through the peripheral mark 702 One of them extends in the Y direction 12 This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) ------------ ·! 丨 --- Order ------- -Line (Please read the notes on the back before filling this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 519701 7449twf.doc / 012 A7 B7 V. Description of the invention (丨 丨) Zone and one of the internal marks 704 Y direction Long strip pattern. Then measure the second X-direction offset along the second X-direction straight line 712. This second x-direction straight line 712 cuts through the other Y-direction extension area of the outer mark 702 and the other Y-direction length of the inner mark 704. Striped pattern. The first Y-direction offset is then measured along a first Y-direction straight line 714, which cuts through an X-direction extension of one of the outer marks 702 and an X-direction strip pattern of one of the inner marks 704. Then measure the second Y-direction offset along the second straight line 716. The second Y-direction straight line 716 cuts through the other X-direction extension of the outer mark 702 and the other X-direction strip of the inner mark 704. pattern. Then, an average offset in the γ direction is obtained from the first Y-direction offset and the second Y-direction offset, and an average X-direction offset is obtained from the first x-direction offset and the second X-direction offset. Shift amount. The method for measuring superimposed marks of the present invention can measure two offsets in the X or γ direction for each superimposed mark, and the conventional superimposed mark § can only be read in the X or Y direction Take an offset, so from a statistical point of view, the measurement of the alignment accuracy of the present invention is more accurate. Moreover, if the superimposed mark of the present invention is locally damaged during chemical mechanical honing, it is only necessary to measure an X-direction offset 5 or a γ-direction offset to achieve the alignment accuracy. Measure. Conversely, because the conventional superimposed mark can only read one offset in the X or Y direction, when part of the superimposed mark is damaged by chemical mechanical honing, it is most likely impossible to complete the measurement of alignment accuracy. . Fig. 11 is a schematic diagram illustrating that a single set of superimposed marks of the present invention can obtain the rotation error of the target axis. 13 _____________ 'This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) —------------------- Order ------- --- line (please read the precautions on the back before filling this page) 519701 7449twf.doc / 012 A7 B7 V. Description of the invention (/ >) Please refer to Section _, using the superimposed mark of the present invention from 700 to The method of analyzing and combining the error factors is based on the superposition method of the overlapping error shown in Fig. 7. The first χ / γ direction straight line 7 丨 〇 / 7 i 4 of the superimposed mark 7OO is superposed. The first X / Y direction offset is measured, and the second x / Y direction offset is measured along the second X / Y direction straight line 712/716 of the superimposed mark 7000. After that, the translation error in the X direction can be obtained from the average 値 Ax of the first / second X-direction offsets', and the translation error in the γ direction can be obtained from the average 値 Aγ of the first / one Y-direction offsets. The difference between the first X-direction offset and the second X-direction offset and Δχ (or the difference between the first γ-direction offset and the second γ-direction offset and the Δγ) can be used to find the standard. Shaft rotation error. Therefore, the superposition mark of the present invention only needs a superposition mark to obtain the axis rotation error. As shown in Fig. 12, it is a schematic diagram illustrating that conventional superimposed marks cannot be calculated in a single group, but must be calculated by different groups of marks. Please refer to FIG. 12, however, the conventional superimposed mark 212 is used to analyze the superimposed error factor. “Since the measuring machine measures the superimposed mark 212 with a fixed width area, it can only be measured by a straight line in the X direction. 310 measures an X-direction offset, and 直线 -direction measures a Υ-direction straight line 312 measures a Υ-direction offset. However, from an X-direction offset and a Υ-direction offset, only the translation error can be obtained, but the standard axis rotation error cannot be obtained. Therefore, if you want to use the conventional superimposed mark 212 to find the axis rotation error, you must measure the X-direction offset and the Υ-direction offset of another superimposed mark, using two X-direction offsets and two Offset in individual directions, 14 ------------------ Order --------- line · (Please read the precautions on the back before filling this page ) Printed by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. The paper size is applicable to the Chinese National Standard (CNS) A4 (210 X 297 mm) 519701 7449twf.doc / 012 A7 5. The description of the invention (/?) Rotation error. To sum up, the present invention has the following advantages: 1. The superimposed mark of the present invention is a reinforced structure, which is particularly effective for resisting chemical mechanical honing in the process of interconnecting metal, so it can reduce chemical mechanical failure. The probability of damage during the grinding process. 2. When the superimposed marker structure and measurement method of the present invention are used, the accuracy of the superimposed error measured can be improved. 3. The present invention only needs a superimposed mark to obtain the rotation error of the scale. 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 some modifications and retouching 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 precautions on the back before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs This paper is in accordance with China National Standard (CNS) A4 (210 X 297 mm)