參考圖式詳細描述了本發明的示例性實施例。在每個圖中，相似的組件由相似的圖式標記表示，並且其重複描述被省略。
＜第一實施例＞
在本發明的第一實施例中，描述了將曝光設備用作微影設備的示例。圖1是用於說明曝光設備100的視圖。曝光設備100包括原版台(保持單元)2、投影光學系統3、基板台5、照明光學系統6、測量單元8和控制單元20。曝光設備100透過以曝光光7穿過上面形成有圖案的原版(倍縮光罩或光罩)1照射基板(晶圓)4，從而將圖案轉印到基板4上。在以下描述中，與投影光學系統3的光軸平行的方向被定義為Z軸方向，在垂直於Z軸方向的平面上相互正交的兩個方向被定義為X軸方向和Y軸方向。
從光源(未示出)發出的光穿過照明光學系統6對保持在原版台2上的原版1進行照明。光源的示例包括高壓水銀燈和準分子雷射器。當光源為準分子雷射器時，不需要在曝光設備100的腔室(chamber)內提供光源，而可以在外部提供光源。要轉印的圖案和稍後描述的原版標記在原版1上形成。對原版1進行照明的光穿過投影光學系統3到達基板4。原版1是形成有預定圖案的倍縮光罩或光罩，並且透射施加自照明光學系統6的光。基板4是例如矽晶圓、玻璃板或薄膜狀基板。
原版台2包括吸附(suck)和保持原版1的吸附裝置。作為透過原版台2的吸附裝置吸附原版1的方法，可以採用真空吸附法、靜電吸附法或其他的吸附法。吸附裝置還可以包括佈置在保持面上用於將原版1保持在原版台2上的多個吸附墊。稍後將詳細描述原版台2。
原版1上的圖案的影像透過投影光學系統3被形成和轉印到施加於基板4上的感光介質(例如抗蝕劑(resist))上。基板台5包括用於保持基板4的吸附裝置。作為透過吸附裝置吸附基板4的方法，可以採用真空吸附法、靜電吸附法或其他的吸附法。基板台5被配置為可移動的。此外，當基板台5沿著垂直於投影光學系統3的光軸的平面二維地逐步移動時，重複曝光基板4上的多個發射區域(shot region)。這是被稱為“步進重複(step-and-repeat)法”的曝光方法。還有被稱為“步進掃描(step-and-scan)法”的曝光方法，在該曝光方法中，透過在同步原版台2和基板台5的同時執行掃描來執行曝光，而第一實施例可以被類似地應用於採用該方法的曝光設備。
測量單元8被佈置在原版台2的向上的方向(Z軸正方向)上，並且測量原版1上提供的原版標記和原版台上提供的基準標記。在圖1中佈置了兩個測量單元8，但測量單元8的數量不限於兩個。稍後將詳細描述測量單元8。
控制單元20控制例如曝光設備100的組件中的每個組件的操作和調整，從而控制用於在基板4上形成圖案的曝光處理。控制單元20是例如現場可程式化閘陣列(FPGA)或其他此類可程式化邏輯裝置(PLD)、專用積體電路(ASIC)、內建程式的計算機，或者是可以透過組合上述類型的全部或部分來配置的資訊處理設備。控制單元20包括：被配置為儲存包括有程式和資料的資訊的ROM；和被配置為儲存用於CPU的工作區和臨時資料的RAM。控制單元20還包括磁性儲存設備(HDD)(未示出)，該磁性儲存設備能夠儲存比ROM和RAM容量更大的資料。控制單元20還包括驅動器，該驅動器被配置為加載CD、DVD、儲存卡或其他此類外部媒體，以從外部媒體讀取/向外部媒體寫入資料。在第一實施例中，假設ROM、RAM、磁儲存裝置和驅動器中的至少一個被設置為儲存單元，並且包括有程式和資料的資訊被保持在該儲存單元中。控制單元20可以(在公共的殼體中)與曝光設備100的其他部分整體地配置，也可以(在分離的殼體中)與曝光設備100的其他部分分離地配置。
接下來描述原版台2和測量單元8。圖2A是用於說明測量單元8、原版台2和保持在原版台2上的原版1的視圖。如圖2A所示，原版標記12被佈置在原版1上。另外，板13被佈置在原版台2上，並且基準標記14被佈置在板13上。在這種情況下，基準標記14相對於投影光學系統3的光軸被佈置在事先定義的基準位置處。
測量單元8還包括光接收元件9和光學元件10，並且透過原版1測量原版1上的原版標記12和原版台2上的基準標記14。測量單元8的光軸方向是沿著Z軸方向的方向，虛線指示測量單元8的焦點位置11。光接收元件9是被配置為接收來自原版標記12和基準標記14穿過光學元件10的光以獲得原版標記12和基準標記14的影像的元件，其可以包括例如CCD、CMOS或其他此類影像拾取元件。光接收元件9被佈置在與測量單元8的焦點位置11共軛的位置上。光學元件10包括至少兩個透鏡，並且將來自原版標記12和基準標記14的光成像到光接收元件9上。測量單元8透過以Z軸方向驅動至少一個光學元件10來調整焦點位置11。控制單元20透過使得測量單元8測量原版標記12和基準標記14，可以獲得原版1和原版台2之間的位置關係。
圖2B是用於說明原版1上的原版標記12、原版台2上的基準標記14和用作基板台5的吸附裝置的吸附墊15的視圖。原版1被放置在原版台2上提供的吸附墊15上，並且原版台2透過吸附墊15吸附和保持原版1。原版標記12和基準標記14可以包括具有其他特定形狀的標記，這些形狀包括圓形、十字形、L形、條形、方形、倒V形和山形。
現在描述在原版1被保持在原版台2上時要執行的焦點測量處理和對準處理。在焦距測量處理中，基於原版標記12的影像與基準標記14的影像的對比度來確定基準焦距位置(以下稱為“基準位置”)。首先，控制單元20獲得已經由測量單元8的光接收元件9所獲得的原版標記12和基準標記14的影像的對比度。然後，控制單元20控制測量單元8，以便將焦點位置11調整到兩個標記的影像的對比度彼此相等的位置。在這種控制下，調整焦點位置11以便使焦點位置11位於原版標記12(原版1)和基準標記14(原版台2)之間。以這種方式，將被調整使得原版標記12的影像的對比度(第一對比度)和基準標記14的影像的對比度(第二對比度)彼此相等的焦點位置11設置為基準位置。在另一種情況下，可以將焦點位置11的中間位置用作基準位置，在該中間位置處，原版標記12和基準標記14的相應對比度的曲線達到峰值。
現在描述從原版標記的影像和基準標記的影像中獲得的對比度。圖3是用於示出焦點位置11和標記的影像的對比度之間關係的圖形。在圖3的圖形中，縱軸指示影像的對比度，橫軸指示焦點位置11。由黑色圓圈連接的曲線指示第一對比度，由白色圓圈連接的曲線指示第二對比度。獲得基準標記的曲線與原版標記的曲線的交點處的焦點位置11作為基準位置。在圖3的圖形中，基準位置被定義為橫軸的原點(Z=0(微米))。在圖3中，將原版標記12和基準標記14設置為具有相同形狀，因此基準標記的曲線和原版標記的曲線具有相同的形狀。然而，原版標記12和基準標記14不限於具有相同形狀的標記，即使基準標記的曲線和原版標記的曲線具有相互不同的形狀，也可以應用第一實施例。
然後，在對準處理中，控制單元20基於由測量單元8獲得的原版標記12和基準標記14的影像獲得原版標記12和基準標記14在XY平面上的位置。然後控制單元20從原版標記12和基準標記14在XY平面上的位置中獲得原版1和原版台2之間的位置關係。控制單元20控制基板台5，使得原版1的圖案的影像在曝光期間基於原版1和原版台2之間的位置關係被投影在基板4上的預定位置處。
在這種情況下，透過將基準位置保持在儲存單元中，控制單元20可以無需每次在原版被保持在原版台上時測量標記來獲得基準位置。在有多個原版1時，可以為多個原版1中的每一個原版1測量基準位置，來為原版1中的每一個原版1保持不同的基準位置。將標識符分配到多個原版1中的每一個原版1，控制單元20可以透過保持原版1的標識符連同基準位置來獲得多個原版1的相應基準位置。
接下來描述用於原版1的異常保持的確定方法。圖4是用於說明根據第一實施例的用於原版1的異常保持的確定方法的流程圖。用於圖4中所示的確定方法的處理由控制單元20執行。控制單元20可以在對準處理之前執行用於原版1的異常保持的確定方法的處理，也可以在對準處理之後執行用於原版1的異常保持的確定方法的處理。透過在對準處理之前執行用於原版1的異常保持的確定方法的處理來獲得基準位置，因此可能省略焦點測量處理。
在步驟S101中，控制單元20使得原版輸送器(未示出)將原版1輸送到原版台2。此時，控制單元20透過將目標位置設置到原版1上的原版標記12在Z軸方向上被疊加在基準標記14上的位置，來控制原版輸送器以將原版1保持在原版台2上。在這種控制下，從原版標記12到測量單元8的光的光學路徑與從基準標記14到測量單元8的光的光學路徑相互重疊。
在步驟S102中，控制單元20確定是否可以獲得基準位置，並且在確定可以獲得基準位置時，將處理推進到步驟S103。同時，在確定無法獲得基準位置時，控制單元20將處理推進到步驟S104。
在這種情況下，控制單元20在基準位置被保持在儲存單元中時確定可以獲得基準位置，而在基準位置未被保持在儲存單元中時確定無法獲得基準位置。在另一種情況下，控制單元20可以透過事先在儲存單元中保持有關被保持在原版台2上的原版1的歷史的資訊來確定是否可以獲得基準位置。即，控制單元20可確定可以獲得用於已經預先被保持在原版台2上的原版1的基準位置，並且可確定無法獲得用於將要首次被保持在原版台2上的原版1的基準位置。
在步驟S103中，控制單元20獲得基準位置。在為多個原版1中的每一個原版1保持基準位置時，獲得了步驟S101中與保持在原版台2上的原版1相對應的基準位置。
在步驟S104中，控制單元20控制測量單元8執行焦點測量處理。即，控制單元20使得測量單元8將測量單元8的焦點位置11調整到第一對比度與第二對比度彼此相等的位置，以獲得基準位置。然後，控制單元20在儲存單元中保持所獲得的基準位置。在這種情況下，在為每個原版1保持基準位置時，控制單元20在步驟S101中也將被保持在原版台2上的原版1的標識符連同基準位置保持在儲存單元中。控制單元20還可以將基準位置發送到外部資訊處理設備，以允許外部資訊處理設備保持基準位置。在這種情況下，在步驟S103中，控制單元20從外部資訊處理設備請求基準位置，並且從外部資訊處理裝置接收基準位置以獲得基準位置。在步驟S102中，控制單元20還向外部資訊處理設備查詢是否可以獲得基準位置，從而確定是否可以獲得基準位置。
在步驟S105中，控制單元20控制測量單元8將測量單元8的焦點位置11移動到步驟S103中獲得的基準位置。測量單元8透過以Z軸方向驅動至少一個光學元件10，將焦點位置11移動到基準位置。
在步驟S106中，控制單元20使得測量單元8測量原版標記12和基準標記14，並且獲得在基準位置處的第一對比度和第二對比度。
在步驟S107中，控制單元20在第二對比度(基準對比度)用作基準的情況下在基準位置處獲得第一對比度的變化量。然後，控制單元20確定第一對比度的變化量是否超出事先定義的可允許範圍。在確定第一對比度的變化量在可允許範圍內時，控制單元20使處理結束。在確定第一對比度的變化量超出可允許範圍時，控制單元20將處理推進到步驟S108。在這種情況下，第一對比度的變化量可以被設置為在基準位置處的第一對比度和第二對比度之間的比率或差值，並且在第一對比度的變化量大於預定閾值(事先定義的值)時，控制單元20可以確定第一對比度的變化量超出可允許範圍。
在步驟S108中，控制單元20確定原版1正在被異常保持在原版台2上。在這種情況下，在步驟S108中確定原版1正在被異常保持在原版台2上時，控制單元20可以中斷或取消用於對基板4進行曝光的曝光處理(用於在基板4上形成圖案的處理)。控制單元20也可以透過使用者介面輸出錯誤。
接下來描述了原版1正在被異常保持在原版台2上的情況。圖5是用於說明在原版1已經被異常保持時出現的原版1和原版台2的視圖。當異物16黏附在原版1或吸附墊15上時，異物16被夾在原版台2(吸附墊15)和被保持在原版台2上的原版1之間。因此，相比於原版1被正常保持而沒有異物16的位置，原版1被保持在以向上的方向(Z軸正方向)移位(displace)的位置，從而以向上的方向(Z軸正方向)移位原版標記12的位置。當原版標記12被向上移位時，相對於焦點位置11的第一對比度被改變。在這種情況下，原版1被異常地保持在原版台2上指的是例如原版1在異物被夾在原版1和原版台2之間的情況下被保持在原版台2上的狀態。然而，本發明不限於這種狀態，並且原版1被異常地保持在原版台2上包括原版1不能被正常地保持在原版台2上，或者原版1以異常方式被保持在原版台2上。例如，原版1被異常地保持在原版台2上也包括原版1由於吸附墊15或原版1的變形而引起的以異常方式被保持在原版台2上。
圖6是用於示出第一實施例中標記的影像的對比度變化的圖形。當原版1已經被異常地保持時，與原版1被正常保持的情況相比，關於原版標記12的曲線被以橫軸方向移動。在圖6中，示出了當在原版1上的原版標記12被向上移位的情況下測量原版標記12時所呈現的原版標記12和基準標記14的影像的對比度。與圖3的曲線相比，第一對比度被改變是在於基準位置(Z=0)處第一對比度被降低。同時，第二對比度因為未被原版1的異常保持所影響而沒有改變。這允許在將第二對比度用作基準的情況下獲得第一對比度的變化。因此，在步驟S107中，控制單元20可以透過確定基準位置處的第一對比度和第二對比度之間的差值或比率是否超出事先定義的可允許範圍來確定原版1是否正在被異常地保持在原版台2上。
在這種情況下，在步驟S107中，控制單元20可以透過將在基準位置處的第一對比度(基準對比度)作為基準來獲得在基準位置處的第一對比度的變化量，該第一對比度在步驟S104中獲得基準位置時呈現。即，可以將第一對比度的變化量設置為在步驟S104中獲得基準位置時呈現的第一對比度與在步驟S107中測量原版標記12時呈現的第一對比度之間的差值或比率。在這種情況下，在步驟S104中，控制單元20在儲存單元中保持在基準位置處的第一對比度。
如上所述，在異物16黏附在原版1或吸附墊15上時，異物16被夾在原版台2(吸附墊15)和被保持在原版台2上的原版1之間。此時，原版標記12的位置被以向上的方向(Z軸正方向)移位。另外，更靠近夾著異物16的吸附墊15的原版標記12在向上的方向上呈現更大的位移量，並且第一對比度的變化量變大。因此，控制單元20可以基於原版標記12和吸附墊15的位置以及原版標記12的第一對比度的變化量的大小來識別夾著異物16的吸附墊15。
在這種情況下，在步驟S108中，在透過使用者介面輸出錯誤時，控制單元20可以在使用者介面上顯示用於識別夾著異物16的吸附墊15的資訊。圖7是用於說明第一實施例中的使用者介面的簡圖。在圖7中說明的示例中，兩個左和右原版標記12中的右原版標記12的對比度變化量為12％，這指示其超過了10％的閾值。圖7中說明的示例還指示，有可能異物16可被夾在四個吸附墊15中靠近右側的原版標記12的兩個吸附墊15(2號和4號)處。在第一實施例中，識別了夾著異物16的兩個吸附墊15，但是在對應於相應吸附墊15的原版標記12在一對一的基礎上被佈置時，也可以識別關於異常保持的一個吸附墊。
如上所述，根據第一實施例，可能透過確定原版標記的影像的對比度的變化是否在可允許範圍內，以在較短的時間段中檢測原版的異常保持。
＜第二實施例＞
接下來描述根據本發明的第二實施例的微影設備。要注意的是，以下未提及的事項可以遵循第一實施例。在第二實施例中描述了這樣的實施例：在該實施例中，使用指示焦點位置11和第一對比度之間的關係的資訊以基於第一對比度的變化來檢測原版1的異常保持。
在圖6中，當改變第一對比度時，整個曲線以橫軸方向移動而不改變曲線的形狀。因此，可以透過使用基準位置(Z=0)處的第一對比度的變化量和指示焦點位置11和第一對比度之間的關係的資訊(第一對比度資訊)來獲得整個曲線在橫軸方向上的移動量。簡而言之，可以獲得焦點位置11相對於原版標記12的變化量。在所獲得的焦點位置11的變化量超出事先定義的可允許範圍時，可能確定原版1正在被異常地保持在原版台2上。
鑒於前述內容，在第二實施例中，第一對比度的變化量和第一對比度資訊被用於檢測原版1的異常保持。
圖8是用於說明根據第二實施例的用於原版的異常保持的確定方法的流程圖。圖8的流程圖在步驟S201至步驟S203與圖4的流程圖不同。因此，省略其他步驟的描述。
在步驟S201中，控制單元20獲得從儲存單元預先獲得的第一對比度資訊。在這種情況下，控制單元20在原版1被正常保持在原版台2上的情況下改變焦點位置11的同時測量原版標記12，並且在儲存單元中保持第一對比度資訊。作為用於保持第一對比度資訊的格式，第一對比度資訊作為焦點位置11和第一對比度的離散資料集被保持在儲存單元中。作為用於保持第一對比度資訊的格式，也可以使用有關透過將焦點位置11用作變量的高斯函數或高階函數對離散資料集進行近似而獲得的函數的資訊。當對比度的變化較小時，也可以使用有關透過將焦點位置11用作變量的線性函數對離散資料集進行近似而獲得的函數的資訊。第一對比度資訊也可以透過仿真獲得。在另一種情況下，外部資訊處理設備可以保持第一對比度資訊。在這種情況下，控制單元20從外部資訊處理設備獲得第一對比度資訊。
在步驟S202中，控制單元20使得測量單元8測量原版標記12，並且在基準位置處獲得第一對比度。在這種情況下，不需要控制單元20測量基準標記14和獲得第二對比度。
在步驟S203中，控制單元20透過使用在步驟S201中獲得的第一對比度資訊和在步驟S202中獲得的基準位置處的第一對比度，獲得焦點位置11相對於原版標記12的變化量。即，控制單元20獲得圖6所示的關於原版標記12的曲線相對於圖3所示的關於原版標記12的曲線在橫軸方向上的移動量。然後，控制單元20確定焦點位置11相對於原版標記12的變化量是否超出事先定義的可允許範圍，並且在確定該變化量在可允許範圍內時，使處理結束。在確定該變化量超出可允許範圍時，控制單元20將處理推進到步驟S108。
如上所述，根據第二實施例，可能透過使用焦點位置和原版標記的影像的對比度之間的關係來確定焦點位置11相對於原版標記12的變化是否在可允許範圍內，以在較短的時間段中檢測原版的異常保持。
＜第三實施例＞
接下來描述根據本發明的第三實施例的微影設備。要注意的是，以下未提及的事項可以遵循第一實施例和第二實施例。在第三實施例中描述了這樣的實施例：在該實施例中，考慮到由於測量單元8的位置位移引起的第一對比度的變化來檢測原版1的異常保持。第三實施例中的測量單元8被配置為可在XY平面內移動。在測量原版標記12和基準標記14時，測量單元8被移動到圖1所示的位置，但是在執行曝光處理時，測量單元8被移動到與曝光光7的光學路徑間隔開的退避(retract)位置。在這種情況下，在測量單元8被再次移動到用於測量原版標記12和基準標記14的位置時，測量單元8在Z軸方向上的位置可能相對於原版台2被移位。即，有可能在測量基準位置時呈現的測量單元8在Z軸方向上相對於原版台2的相對位置與在確定原版1的異常保持時呈現的測量單元8在Z軸方向上相對於原版台2的相對位置相互不同。不僅在原版1正在被異常保持時，而且在測量單元8在Z軸方向上相對於原版台2的相對位置被改變時，第一對比度都被改變。因此，基於測量單元8在Z軸方向上的位置不改變的假設，有可能在基於第一對比度的變化來確定原版1的異常保持時錯誤地確定原版1的異常保持。
圖9是用於示出由於測量單元8的位置變化而引起的標記的影像的對比度變化的圖形。當測量單元8在Z軸方向上的位置被改變時，與圖3的曲線圖相比，第一對比度曲線和第二對比曲線被改變。這是因為測量單元8在Z軸方向上的位置已經被向下改變。因此，即使當原版1未被異常保持時，也可能在測量單元8的位置在Z軸方向上被改變時改變在基準位置處的第一對比度。
鑒於前述內容，在第三實施例中，考慮到由於測量單元8的位置變化引起的第一對比度的變化來檢測原版1的異常保持。
圖10是用於說明根據第三實施例的用於原版的異常保持的確定方法的流程圖。圖10的流程圖在步驟S301至步驟S303與圖4的流程圖不同。因此，省略其他步驟的描述。
在步驟S301中，控制單元20以與步驟S201中相同的方式獲得事先從儲存單元獲得的第一對比度資訊。另外，控制單元20獲得事先從儲存單元獲得的指示焦點位置11和第二對比度之間的關係的資訊(第二對比度資訊)。在這種情況下，控制單元20在原版1被正常保持在原版台2上的情況下改變焦點位置11的同時測量基準標記14，並且在儲存單元中保持第二對比度資訊。在這種情況下，作為用於保持第二對比度資訊的格式，第二對比度資訊作為焦點位置11和第二對比度的離散資料集被保持在儲存單元中。作為用於保持第二對比度資訊的格式，也可以使用有關透過將焦點位置11用作變量的高斯函數或高階函數對離散資料集進行近似而獲得的函數的資訊。當對比度的變化較小時，也可以使用有關透過將焦點位置11用作變量的線性函數對離散資料集進行近似而獲得的函數的資訊。第二對比度資訊也可以透過仿真獲得，而不需要實際測量對比度。在另一種情況下，外部資訊處理設備可以保持第二對比度資訊。在這種情況下，控制單元20從外部資訊處理設備獲得第二對比度資訊。
在步驟S302中，控制單元20透過使用第一對比度資訊和第二對比度資訊來校正基準位置處的基準標記14和原版標記12的影像的對比度變化。首先，控制單元20透過使用在步驟S301中獲得的第一對比度資訊和在步驟S106中獲得的在基準位置處的第一對比度，獲得焦點位置11相對於原版標記12的變化量。即，控制單元20獲得圖9所示的關於原版標記12的曲線在橫軸方向上相對於圖3所示的關於原版標記12的曲線的移動量。
接下來，控制單元20透過使用在步驟S301中獲得的第二對比度資訊和在步驟S106中獲得的在基準位置處的第二對比度，獲得焦點位置11相對於基準標記14的變化量。即，控制單元20獲得圖9所示的關於基準標記14的曲線在橫軸方向上相對於圖3所示的關於基準標記14的曲線的移動量。
接下來，控制單元20校正焦點位置11相對於原版標記12的變化量，以便取消焦點位置11相對於基準標記14的變化量。例如，在已經將關於基準標記14的曲線在橫軸上向右(正方向)移動時，控制單元20校正關於原版標記12的曲線以便將該曲線在橫軸上向左(負方向)移動。然後，控制單元20透過使用關於原版標記12的已校正曲線來校正基準位置(Z=0)處的第一對比度。
然後，控制單元20校正焦點位置11相對於基準標記14的變化量，以便取消焦點位置11相對於基準標記14的變化量。例如，在已經將關於基準標記14的曲線在橫軸上向右(正方向)移動時，控制單元20校正關於基準標記14的曲線以便將該曲線在橫軸上向左(負方向)移動。然後，控制單元20透過使用關於基準標記14的已校正曲線來校正基準位置(Z=0)處的第二對比度。
在步驟S303中，控制單元20參考在步驟S302中校正的第二對比度(基準對比度)，獲得在步驟S302中校正的第一對比度的變化量。然後，控制單元20確定第一對比度的變化量是否超出事先定義的可允許範圍。在確定第一對比度的變化量在可允許範圍內時，控制單元20使處理結束。在確定第一對比度的變化量超出可允許範圍時，控制單元20將處理推進到步驟S108。另外，控制單元20可以參考在從事先獲得的第一對比度資訊獲得的基準位置處的第一對比度，以獲得在步驟S302中校正的第一對比度的變化量。
在步驟S302中，當測量單元8在Z軸方向上相對於原版台2的位置變化較大時，控制單元20可以確定該焦點異常。例如，控制單元20確定焦點位置11相對於基準標記14的變化量是否在可允許範圍內。當焦點位置11相對於基準標記14的變化量超出可允許範圍時，控制單元20也可以透過使用者介面輸出錯誤以使處理結束。
根據第三實施例的用於原版的異常保持的確定方法可以單獨使用，但是也可以與根據第一實施例或第二實施例的用於原版的異常保持的確定方法組合使用。即，在執行根據第一實施例或第二實施例的用於原版的異常保持的確定方法之後確定原版1正在原版台2上被異常保持時，可以執行根據第三實施例的用於原版的異常保持的確定方法。
如上所述，根據第三實施例，可能透過確定原版標記的影像的對比度的變化是否在可允許範圍內，在較短的時間段中檢測到原版的異常保持。另外，可以考慮由於測量單元8的位置變化引起的第一對比度的變化，因此可能抑制對原版的異常保持的錯誤檢測。
＜第四實施例＞
接下來描述根據本發明的第四實施例的微影設備。要注意的是，以下未提及的事項可以遵循第一實施例至第三實施例。在第四實施例中描述了這樣的實施例：在該實施例中，基於第一光量的變化，使用指示焦點位置11和第一光量之間的關係的資訊來檢測原版1的異常保持。
圖11是用於說明根據第四實施例的微影設備的視圖。第四實施例中的曝光設備100包括在基板台5上的板21和被配置為測量基板台5內部的光量的光接收元件22。
圖12是用於說明在第四實施例中的基板台5的視圖。板21被佈置在基板台5上，並且提供有用於光量測量的基準標記24。光接收元件22被佈置在基板台5的內部，並且在板21和基準標記24的下方。
用於光量測量的原版標記12在原版1的照亮區域中提供，並且原版標記12被照亮光學系統6照亮，從而在投影光學系統3的基板側形成原版標記12的影像25。
考慮到投影光學系統3的成像放大率，將原版標記12和基準標記24設計為使得原版標記12的影像25和基準標記24具有相同的形狀。因此，在原版標記12的影像25和基準標記24被佈置在相互共軛的位置時，原版標記12的影像25和基準標記24相互疊加，並且來自原版標記12的影像25的光透過基準標記24的開口部分透射。透射光23的光量由佈置在板21下方的光接收元件22測量。當基準標記24變得更靠近形成原版標記12的影像25的焦點位置時，透過其透射的光量增加，並且由光接收元件22測量的光量增加。在第四實施例中，原版標記12的影像25和基準標記24被設置為具有相同的形狀，但是原版標記12的影像25和基準標記24可以具有不同的形狀，只要從這些形狀中能夠獲得在基板台上的板21和原版1之間的位置關係即可。
另外，基板台5被配置為可移動的，因此可能移動佈置在基板台5上/中的板21、基準標記24和光接收元件22。因此，控制單元20可以在驅動基板台5的同時測量來自光接收元件22的光量，並且可以基於所測量的光量來檢測焦點位置。
現在描述用於檢測焦點位置的處理。在用於檢測焦點位置的處理中，基於由光接收元件22測量的光量來確定基準焦點位置(以下稱為“基準位置”)。首先，控制單元20在沿Z軸方向驅動基板台5的同時獲得由光接收元件22測量的光23的光量。然後，控制單元20透過將基板台5的基準位置設置為所獲得的光量被最大化的位置，以控制基板台5。控制單元20還將在基準位置處測量的光23的光量設置為基準光量。
現在描述由光接收元件22測量的光量。圖13是用於示出基板台5在Z軸方向上的位置與由光接收元件22測量的光量之間的關係的圖形。在圖13的圖形中，縱軸指示由光接收元件22測量的光量，而橫軸指示基板台5在Z軸方向上的位置。獲得基板台5的基準位置作為基板台5上光量被最大化所處的位置。在圖13的圖形中，基準位置被定義為橫軸的原點(Z=0(微米))。在第一實施例中的對比度的情況下，獲得第一對比度和第二對比度的兩條曲線。然而，在第四實施例中，將透過基準標記24的開口部分透射的光23的光量設置為縱軸，因此獲得該光量的一條曲線。
在這種情況下，透過將基準位置保持在儲存單元中，控制單元20可以無需每次在原版1被保持在原版台2上時測量該標記來獲得基準位置。在有多個原版1時，可以為多個原版1中的每一個原版1測量成像位置，來為原版1中的每一個原版1保持不同的成像位置。將標識符分配給多個原版1中的每一個原版1，控制單元20透過保持原版1的標識符連同基準位置來獲得多個原版1的相應基準位置。
接下來描述用於原版1的異常保持的確定方法。如圖5所示，當異物16被夾在原版1和原版台2(吸附墊15)之間以使原版1的位置以向上的方向(Z軸正方向)移位時，形成原版標記12的影像25的焦點位置也被移位。在那種情況下，整個曲線在橫軸方向上被移動而不改變圖13中的曲線的形狀。因此，透過使用基準位置(Z=0)處的光量的變化量和指示焦點位置和光量之間的關係的資訊(光量資訊)，可以獲得整個圖線在橫軸方向上的移動量。簡而言之，可以獲得焦點位置相對於原版標記12的影像25的變化量。當所獲得的焦點位置的變化量超出事先定義的可允許範圍時，可能確定原版1正在被異常保持在原版台2上。
圖14是用於說明根據第四實施例的用於原版1的異常保持的確定方法的流程圖。圖14的流程圖在步驟S401至步驟S405與圖4的流程圖不同。因此，省略其他步驟的描述。
在步驟S401中，控制單元20控制基板台5和光接收元件22以執行焦點測量處理。即，控制單元20將基板台5驅動到由光接收元件22測量的光23的光量被最大化的位置，從而獲得基準位置。
在步驟S402中，控制單元20控制基板台5以將基板台5在Z軸方向上的位置移動到在步驟S103中獲得的基準位置。
在步驟S403中，控制單元20從儲存單元獲得事先獲得的光量資訊。在這種情況下，控制單元20在原版1被正常保持在原版台2上的情況下改變基板台5在Z軸方向上的位置的同時，透過光接收元件22測量光量，並在儲存單元中保持光量資訊。
在步驟S404中，控制單元20使得光接收元件22測量光23的光量，並且獲得基準位置處的光量。
在步驟S405中，控制單元20透過使用在步驟S403中獲得的光量資訊和在步驟S404中獲得基準位置處的光量，以獲得形成原版標記12的影像25的焦點位置的變化量。即，控制單元20獲得圖13所示的關於光量的曲線在橫軸上的移動量。然後，控制單元20確定形成原版標記12的影像25的焦點位置的變化量是否超出事先定義的可允許範圍，並且當確定該變化量在可允許範圍內時，使處理結束。當確定該變化量超出可允許範圍時，控制單元20將處理推進到步驟S108。
如上所述，根據第四實施例，可能透過使用焦點位置和光量之間的關係確定形成原版標記12的影像25的焦點位置的變化是否在可允許範圍內，以在較短的時間段內檢測原版的異常保持。
(製造物品的方法)
根據本發明的製造物品的方法適合於製造物品，例如，半導體裝置、磁性儲存媒體、液晶顯示裝置或其他此類裝置。該製造方法包括透過使用曝光設備對於施加有光敏劑的基板進行曝光(在基板上形成圖案)，以及對所曝光的基板進行顯影(處理基板)。該製造方法還可以包括執行氧化、膜形成、氣相沉積、摻雜、平坦化、蝕刻、抗蝕劑剝離、切割、接合、封裝以及其他此類已知的處理。與相關技術相比，根據本發明的製造物品的方法在物品的性能、質量、生產率和生產成本中的至少一項是有利的。
以上描述了本發明的示例性實施例，但是應當理解的是，本發明不限於那些實施例，並且在不偏離本發明的精神的情況下可以對其進行各種修改和改變。曝光設備已經被描述作為微影設備的示例，但是本發明不限於此。
作為微影設備的示例，可以使用壓印設備，該壓印設備被配置為透過使用具有不平坦圖案的模具(圖案或模板)在基板上形成壓印材料的圖案。作為微影設備的另一示例，可以使用被配置為執行模製的平坦化設備，以便透過使用具有平坦部分而沒有不平坦圖案的模具(平坦模板)來對基板上的組合物進行平坦化。作為微影設備的又一示例，可以使用被配置為使用帶電粒子束(例如，電子束或離子束)穿過帶電粒子光學系統在基板上執行繪製以在基板上形成圖案的繪製設備或其他此類設備。
第一至第四實施例不僅可以單獨實現，還可以以第一至第四實施例的任意組合來實現。
根據本發明的至少一個實施例，可能提供能夠在較短的時間段中檢測原版的異常保持的微影設備、確定方法以及製造物品的方法。
雖然已經參考示例性實施例描述了本發明，但是應當理解的是，本發明不限於所公開的示例性實施例。以下申請專利範圍的範圍應被賦予最寬的解釋，以便包含所有此類修改以及等同的結構和功能。The exemplary embodiments of the present invention are described in detail with reference to the drawings. In each figure, similar components are represented by similar drawing symbols, and their repeated description is omitted.
<First embodiment>
In the first embodiment of the present invention, an example in which the exposure apparatus is used as the lithography apparatus is described. FIG. 1 is a view for explaining the exposure apparatus 100. The exposure apparatus 100 includes an original plate stage (holding unit) 2, a projection optical system 3, a substrate stage 5, an illumination optical system 6, a measurement unit 8 and a control unit 20. The exposure apparatus 100 irradiates the substrate (wafer) 4 with exposure light 7 passing through the original plate (reducing mask or mask) 1 on which the pattern is formed, thereby transferring the pattern to the substrate 4. In the following description, the direction parallel to the optical axis of the projection optical system 3 is defined as the Z-axis direction, and two directions orthogonal to each other on a plane perpendicular to the Z-axis direction are defined as the X-axis direction and the Y-axis direction.
Light emitted from a light source (not shown) passes through the illumination optical system 6 to illuminate the original plate 1 held on the original plate table 2. Examples of light sources include high-pressure mercury lamps and excimer lasers. When the light source is an excimer laser, the light source does not need to be provided in the chamber of the exposure apparatus 100, but the light source may be provided outside. A pattern to be transferred and an original plate mark described later are formed on the original plate 1. The light illuminating the original plate 1 passes through the projection optical system 3 to reach the substrate 4. The original plate 1 is a reduction mask or a mask formed with a predetermined pattern, and transmits light applied from the illumination optical system 6. The substrate 4 is, for example, a silicon wafer, a glass plate, or a film-like substrate.
The original plate table 2 includes sucking and a suction device for holding the original plate 1. As a method of adsorbing the original plate 1 through the adsorption device of the original plate table 2, a vacuum adsorption method, an electrostatic adsorption method, or other adsorption methods can be used. The adsorption device may further include a plurality of adsorption pads arranged on the holding surface for holding the original plate 1 on the original plate table 2. The master station 2 will be described in detail later.
The image of the pattern on the original plate 1 is formed and transferred to a photosensitive medium (for example, resist) applied on the substrate 4 through the projection optical system 3. The substrate stage 5 includes a suction device for holding the substrate 4. As a method of adsorbing the substrate 4 through the adsorption device, a vacuum adsorption method, an electrostatic adsorption method, or other adsorption methods can be used. The substrate stage 5 is configured to be movable. In addition, when the substrate stage 5 is gradually moved two-dimensionally along a plane perpendicular to the optical axis of the projection optical system 3, multiple shot regions on the substrate 4 are repeatedly exposed. This is an exposure method called the "step-and-repeat method". There is also an exposure method called a "step-and-scan method" in which exposure is performed by performing scanning while synchronizing the master stage 2 and the substrate stage 5. The first implementation The example can be similarly applied to an exposure apparatus adopting this method.
The measuring unit 8 is arranged in the upward direction (the positive direction of the Z-axis) of the original plate 2 and measures the original plate mark provided on the original plate 1 and the fiducial mark provided on the original plate table. Two measurement units 8 are arranged in FIG. 1, but the number of measurement units 8 is not limited to two. The measurement unit 8 will be described in detail later.
The control unit 20 controls, for example, the operation and adjustment of each of the components of the exposure apparatus 100, thereby controlling the exposure process for forming a pattern on the substrate 4. The control unit 20 is, for example, a field programmable gate array (FPGA) or other such programmable logic device (PLD), a dedicated integrated circuit (ASIC), a computer with a built-in program, or a computer that can combine all the above types Or partly configured information processing equipment. The control unit 20 includes: a ROM configured to store information including programs and data; and a RAM configured to store a work area for the CPU and temporary data. The control unit 20 also includes a magnetic storage device (HDD) (not shown), which can store data with a larger capacity than ROM and RAM. The control unit 20 also includes a drive, which is configured to load a CD, a DVD, a memory card or other such external media to read/write data from the external media. In the first embodiment, it is assumed that at least one of ROM, RAM, magnetic storage device, and drive is set as a storage unit, and information including programs and data is held in the storage unit. The control unit 20 may be configured integrally with other parts of the exposure apparatus 100 (in a common housing), or may be configured separately from other parts of the exposure apparatus 100 (in a separate housing).
Next, the master table 2 and the measuring unit 8 are described. FIG. 2A is a view for explaining the measurement unit 8, the original plate table 2, and the original plate 1 held on the original plate table 2. As shown in FIG. 2A, the original plate mark 12 is arranged on the original plate 1. In addition, the board 13 is arranged on the original plate table 2 and the reference mark 14 is arranged on the board 13. In this case, the reference mark 14 is arranged at a reference position defined in advance with respect to the optical axis of the projection optical system 3.
The measuring unit 8 also includes a light receiving element 9 and an optical element 10, and measures the original plate mark 12 on the original plate 1 and the reference mark 14 on the original plate table 2 through the original plate 1. The optical axis direction of the measuring unit 8 is a direction along the Z axis direction, and the dotted line indicates the focal position 11 of the measuring unit 8. The light receiving element 9 is an element configured to receive light from the master mark 12 and the reference mark 14 passing through the optical element 10 to obtain the image of the master mark 12 and the reference mark 14, and it may include, for example, CCD, CMOS or other such images. Pick up components. The light receiving element 9 is arranged at a position conjugate to the focal position 11 of the measurement unit 8. The optical element 10 includes at least two lenses, and images light from the master mark 12 and the reference mark 14 onto the light receiving element 9. The measurement unit 8 adjusts the focus position 11 by driving at least one optical element 10 in the Z-axis direction. The control unit 20 can obtain the positional relationship between the original plate 1 and the original plate table 2 by causing the measuring unit 8 to measure the original plate mark 12 and the reference mark 14.
FIG. 2B is a view for explaining the original plate mark 12 on the original plate 1, the reference mark 14 on the original plate table 2, and the suction pad 15 used as the suction device of the substrate table 5. The original plate 1 is placed on the suction pad 15 provided on the original plate table 2, and the original plate table 2 sucks and holds the original plate 1 through the suction pad 15. The original mark 12 and the fiducial mark 14 may include marks having other specific shapes, including a circle, a cross, an L shape, a bar shape, a square shape, an inverted V shape, and a mountain shape.
The focus measurement process and the alignment process to be executed when the original plate 1 is held on the original plate table 2 will now be described. In the focal length measurement process, the reference focal length position (hereinafter referred to as “reference position”) is determined based on the contrast between the image of the original mark 12 and the image of the reference mark 14. First, the control unit 20 obtains the contrast of the images of the master mark 12 and the reference mark 14 that have been obtained by the light receiving element 9 of the measuring unit 8. Then, the control unit 20 controls the measurement unit 8 so as to adjust the focus position 11 to a position where the contrast of the two marked images is equal to each other. Under this control, the focus position 11 is adjusted so that the focus position 11 is located between the original plate mark 12 (original plate 1) and the reference mark 14 (original plate table 2). In this way, the focus position 11 adjusted so that the contrast of the image of the master mark 12 (first contrast) and the contrast of the image of the reference mark 14 (second contrast) are equal to each other is set as the reference position. In another case, the middle position of the focus position 11 may be used as the reference position, at which the curve of the corresponding contrast of the master mark 12 and the reference mark 14 reaches a peak.
The contrast obtained from the image of the original mark and the image of the fiducial mark will now be described. FIG. 3 is a graph for showing the relationship between the focus position 11 and the contrast of the marked image. In the graph of FIG. 3, the vertical axis indicates the contrast of the image, and the horizontal axis indicates the focus position 11. The curve connected by black circles indicates the first contrast, and the curve connected by white circles indicates the second contrast. The focal position 11 at the intersection of the curve of the reference mark and the curve of the original plate mark is obtained as the reference position. In the graph of FIG. 3, the reference position is defined as the origin of the horizontal axis (Z=0 (micrometer)). In FIG. 3, the original plate mark 12 and the reference mark 14 are set to have the same shape, so the curve of the reference mark and the curve of the original plate mark have the same shape. However, the master mark 12 and the reference mark 14 are not limited to marks having the same shape, and even if the curve of the reference mark and the curve of the master mark have mutually different shapes, the first embodiment can be applied.
Then, in the alignment process, the control unit 20 obtains the positions of the original plate mark 12 and the reference mark 14 on the XY plane based on the images of the original plate mark 12 and the reference mark 14 obtained by the measuring unit 8. The control unit 20 then obtains the positional relationship between the original plate 1 and the original plate table 2 from the positions of the original plate mark 12 and the reference mark 14 on the XY plane. The control unit 20 controls the substrate stage 5 so that the image of the pattern of the original plate 1 is projected at a predetermined position on the substrate 4 based on the positional relationship between the original plate 1 and the original plate table 2 during exposure.
In this case, by holding the reference position in the storage unit, the control unit 20 can obtain the reference position without measuring the mark every time the original plate is held on the original plate table. When there are multiple original plates 1, the reference position can be measured for each original plate 1 of the multiple original plates 1 to maintain a different reference position for each original plate 1 in the original plate 1. The identifier is assigned to each original plate 1 of the plurality of original plates 1, and the control unit 20 can obtain the corresponding reference position of the plurality of original plates 1 by keeping the identifier of the original plate 1 together with the reference position.
Next, the determination method for the abnormality retention of the original plate 1 is described. FIG. 4 is a flowchart for explaining a determination method for abnormal retention of the original plate 1 according to the first embodiment. The processing for the determination method shown in FIG. 4 is executed by the control unit 20. The control unit 20 may perform the processing of the determination method for abnormality retention of the original plate 1 before the alignment processing, or may perform the processing of the determination method for the abnormality retention of the original plate 1 after the alignment processing. The reference position is obtained by performing the processing of the determination method for abnormal retention of the original plate 1 before the alignment processing, and therefore the focus measurement processing may be omitted.
In step S101, the control unit 20 causes an original plate conveyer (not shown) to convey the original plate 1 to the original plate table 2. At this time, the control unit 20 controls the original plate conveyor to hold the original plate 1 on the original plate table 2 by setting the target position to the position where the original plate mark 12 on the original plate 1 is superimposed on the reference mark 14 in the Z-axis direction. Under this control, the optical path of the light from the master mark 12 to the measurement unit 8 and the optical path of the light from the reference mark 14 to the measurement unit 8 overlap with each other.
In step S102, the control unit 20 determines whether the reference position can be obtained, and when it is determined that the reference position can be obtained, advances the process to step S103. Meanwhile, when it is determined that the reference position cannot be obtained, the control unit 20 advances the process to step S104.
In this case, the control unit 20 determines that the reference position can be obtained when the reference position is held in the storage unit, and determines that the reference position cannot be obtained when the reference position is not held in the storage unit. In another case, the control unit 20 can determine whether the reference position can be obtained by holding information about the history of the original plate 1 held on the original plate table 2 in the storage unit in advance. That is, the control unit 20 may determine that the reference position for the original plate 1 that has been held on the original plate table 2 in advance can be obtained, and may determine that the reference position for the original plate 1 to be held on the original plate table 2 for the first time cannot be obtained.
In step S103, the control unit 20 obtains the reference position. When the reference position is maintained for each original plate 1 among the plurality of original plates 1, the reference position corresponding to the original plate 1 held on the original plate table 2 in step S101 is obtained.
In step S104, the control unit 20 controls the measurement unit 8 to perform focus measurement processing. That is, the control unit 20 causes the measurement unit 8 to adjust the focus position 11 of the measurement unit 8 to a position where the first contrast and the second contrast are equal to each other to obtain the reference position. Then, the control unit 20 maintains the obtained reference position in the storage unit. In this case, while maintaining the reference position for each master plate 1, the control unit 20 also keeps the identifier of the master plate 1 held on the master plate table 2 in the storage unit together with the reference position in step S101. The control unit 20 may also send the reference position to the external information processing device to allow the external information processing device to maintain the reference position. In this case, in step S103, the control unit 20 requests the reference position from the external information processing device, and receives the reference position from the external information processing device to obtain the reference position. In step S102, the control unit 20 also queries the external information processing device whether the reference position can be obtained, thereby determining whether the reference position can be obtained.
In step S105, the control unit 20 controls the measurement unit 8 to move the focal position 11 of the measurement unit 8 to the reference position obtained in step S103. The measurement unit 8 drives at least one optical element 10 in the Z-axis direction to move the focal position 11 to the reference position.
In step S106, the control unit 20 causes the measuring unit 8 to measure the original plate mark 12 and the reference mark 14, and obtain the first contrast and the second contrast at the reference position.
In step S107, the control unit 20 obtains the amount of change in the first contrast at the reference position with the second contrast (reference contrast) used as a reference. Then, the control unit 20 determines whether the amount of change in the first contrast exceeds the allowable range defined in advance. When it is determined that the amount of change in the first contrast is within the allowable range, the control unit 20 ends the process. When it is determined that the amount of change in the first contrast exceeds the allowable range, the control unit 20 advances the process to step S108. In this case, the amount of change in the first contrast can be set as the ratio or difference between the first contrast and the second contrast at the reference position, and the amount of change in the first contrast is greater than a predetermined threshold (predefined When the value of), the control unit 20 can determine that the amount of change in the first contrast exceeds the allowable range.
In step S108, the control unit 20 determines that the original plate 1 is being abnormally held on the original plate table 2. In this case, when it is determined in step S108 that the original plate 1 is being abnormally held on the original plate table 2, the control unit 20 may interrupt or cancel the exposure process for exposing the substrate 4 (for forming a pattern on the substrate 4). Processing). The control unit 20 can also output errors through the user interface.
Next, the case where the original plate 1 is being abnormally held on the original plate table 2 is described. FIG. 5 is a view for explaining the original plate 1 and the original plate table 2 that appear when the original plate 1 has been abnormally held. When the foreign matter 16 adheres to the original plate 1 or the adsorption pad 15, the foreign matter 16 is sandwiched between the original plate table 2 (the adsorption pad 15) and the original plate 1 held on the original plate table 2. Therefore, compared to the position where the original plate 1 is normally held without foreign matter 16, the original plate 1 is held at a position displaced in the upward direction (positive direction of the Z-axis), thereby moving in the upward direction (positive direction of the Z-axis). ) Shift the position of the original mark 12. When the master mark 12 is shifted upward, the first contrast with respect to the focus position 11 is changed. In this case, the original plate 1 being abnormally held on the original plate table 2 refers to, for example, a state where the original plate 1 is held on the original plate table 2 with a foreign matter sandwiched between the original plate 1 and the original plate table 2. However, the present invention is not limited to this state, and the original plate 1 is abnormally held on the original plate table 2 including the original plate 1 cannot be normally held on the original plate table 2 or the original plate 1 is held on the original plate table 2 in an abnormal manner. For example, the original plate 1 being abnormally held on the original plate table 2 also includes the original plate 1 being held on the original plate table 2 in an abnormal manner due to deformation of the suction pad 15 or the original plate 1.
Fig. 6 is a graph for showing changes in contrast of marked images in the first embodiment. When the original plate 1 has been abnormally held, compared to the case where the original plate 1 is normally held, the curve with respect to the original plate mark 12 is moved in the horizontal axis direction. In FIG. 6, the contrast of the image of the original plate mark 12 and the reference mark 14 that appears when the original plate mark 12 is measured with the original plate mark 12 on the original plate 1 shifted upward is shown. Compared with the curve in FIG. 3, the first contrast is changed because the first contrast is reduced at the reference position (Z=0). At the same time, the second contrast is not changed because it is not affected by the abnormal retention of the original plate 1. This allows a change in the first contrast to be obtained with the second contrast being used as a reference. Therefore, in step S107, the control unit 20 can determine whether the original plate 1 is being abnormally maintained by determining whether the difference or ratio between the first contrast and the second contrast at the reference position exceeds the allowable range defined in advance. On the original stage 2.
In this case, in step S107, the control unit 20 can obtain the amount of change in the first contrast at the reference position by taking the first contrast at the reference position (reference contrast) as a reference, the first contrast being at Presented when the reference position is obtained in step S104. That is, the amount of change in the first contrast can be set as the difference or ratio between the first contrast presented when the reference position is obtained in step S104 and the first contrast presented when the master mark 12 is measured in step S107. In this case, in step S104, the control unit 20 maintains the first contrast at the reference position in the storage unit.
As described above, when the foreign matter 16 adheres to the original plate 1 or the adsorption pad 15, the foreign matter 16 is sandwiched between the original plate table 2 (the suction pad 15) and the original plate 1 held on the original plate table 2. At this time, the position of the master mark 12 is shifted in the upward direction (the positive direction of the Z axis). In addition, the master mark 12 closer to the suction pad 15 sandwiching the foreign matter 16 exhibits a larger displacement amount in the upward direction, and the amount of change in the first contrast becomes larger. Therefore, the control unit 20 can identify the suction pad 15 sandwiching the foreign matter 16 based on the positions of the master mark 12 and the suction pad 15 and the magnitude of the change amount of the first contrast of the master mark 12.
In this case, in step S108, when an error is output through the user interface, the control unit 20 may display information for identifying the adsorption pad 15 with the foreign object 16 on the user interface. Fig. 7 is a schematic diagram for explaining the user interface in the first embodiment. In the example illustrated in FIG. 7, the contrast change amount of the right master mark 12 of the two left and right master marks 12 is 12%, which indicates that it exceeds the threshold value of 10%. The example illustrated in FIG. 7 also indicates that there is a possibility that foreign matter 16 may be caught in the two adsorption pads 15 (No. 2 and No. 4) near the original mark 12 on the right side among the four adsorption pads 15. In the first embodiment, the two adsorption pads 15 sandwiching the foreign matter 16 are identified, but when the original marks 12 corresponding to the corresponding adsorption pads 15 are arranged on a one-to-one basis, it is also possible to identify A suction pad.
As described above, according to the first embodiment, it is possible to determine whether the change in the contrast of the original plate mark image is within the allowable range to detect abnormal retention of the original plate in a short period of time.
<Second embodiment>
Next, a lithography apparatus according to a second embodiment of the present invention will be described. It should be noted that matters not mentioned below can follow the first embodiment. In the second embodiment, an embodiment is described in which information indicating the relationship between the focus position 11 and the first contrast is used to detect abnormal retention of the original plate 1 based on the change in the first contrast.
In FIG. 6, when the first contrast is changed, the entire curve moves in the horizontal axis direction without changing the shape of the curve. Therefore, it is possible to obtain the entire curve in the horizontal axis direction by using the amount of change in the first contrast at the reference position (Z=0) and the information indicating the relationship between the focus position 11 and the first contrast (first contrast information) The amount of movement. In short, the amount of change in the focus position 11 with respect to the master mark 12 can be obtained. When the obtained change amount of the focus position 11 exceeds the allowable range defined in advance, it may be determined that the original plate 1 is being abnormally held on the original plate table 2.
In view of the foregoing, in the second embodiment, the amount of change in the first contrast and the first contrast information are used to detect abnormal retention of the original plate 1.
FIG. 8 is a flowchart for explaining a determination method for abnormal retention of an original plate according to the second embodiment. The flowchart of FIG. 8 is different from the flowchart of FIG. 4 in steps S201 to S203. Therefore, the description of other steps is omitted.
In step S201, the control unit 20 obtains the first contrast information obtained in advance from the storage unit. In this case, the control unit 20 measures the original plate mark 12 while changing the focus position 11 while the original plate 1 is normally held on the original plate table 2, and maintains the first contrast information in the storage unit. As a format for holding the first contrast information, the first contrast information is held in the storage unit as a discrete data set of the focal position 11 and the first contrast. As a format for maintaining the first contrast information, it is also possible to use information about a function obtained by approximating a discrete data set by using a Gaussian function or a higher-order function using the focus position 11 as a variable. When the change in contrast is small, it is also possible to use information about a function obtained by approximating a discrete data set by a linear function using the focal position 11 as a variable. The first contrast information can also be obtained through simulation. In another case, the external information processing device can maintain the first contrast information. In this case, the control unit 20 obtains the first contrast information from the external information processing device.
In step S202, the control unit 20 causes the measuring unit 8 to measure the master mark 12, and obtain the first contrast at the reference position. In this case, there is no need for the control unit 20 to measure the reference mark 14 and obtain the second contrast.
In step S203, the control unit 20 obtains the amount of change in the focus position 11 with respect to the master mark 12 by using the first contrast information obtained in step S201 and the first contrast at the reference position obtained in step S202. That is, the control unit 20 obtains the amount of movement in the horizontal axis direction of the curve about the master mark 12 shown in FIG. 6 with respect to the curve about the master mark 12 shown in FIG. 3. Then, the control unit 20 determines whether the amount of change in the focus position 11 with respect to the master mark 12 exceeds the allowable range defined in advance, and when it is determined that the amount of change is within the allowable range, the processing ends. When it is determined that the amount of change exceeds the allowable range, the control unit 20 advances the process to step S108.
As described above, according to the second embodiment, it is possible to determine whether the change of the focus position 11 with respect to the master mark 12 is within the allowable range by using the relationship between the focus position and the contrast of the image of the master mark, so as to be shorter Detect the abnormal retention of the original version during the time period.
<The third embodiment>
Next, a lithography apparatus according to a third embodiment of the present invention will be described. It should be noted that matters not mentioned below can follow the first embodiment and the second embodiment. In the third embodiment, an embodiment is described in which abnormal retention of the original plate 1 is detected in consideration of the change in the first contrast due to the positional displacement of the measurement unit 8. The measurement unit 8 in the third embodiment is configured to be movable in the XY plane. When measuring the original plate mark 12 and the reference mark 14, the measuring unit 8 is moved to the position shown in FIG. 1, but when the exposure processing is performed, the measuring unit 8 is moved to a retracted distance from the optical path of the exposure light 7. )position. In this case, when the measuring unit 8 is moved to the position for measuring the original plate mark 12 and the reference mark 14 again, the position of the measuring unit 8 in the Z-axis direction may be shifted relative to the original plate table 2. That is, it is possible that the relative position of the measurement unit 8 in the Z-axis direction relative to the original plate table 2 presented when the reference position is measured and the measurement unit 8 presented when the abnormal hold of the original plate 1 is determined relative to the original plate table in the Z-axis direction The relative positions of 2 are different from each other. Not only when the original plate 1 is being abnormally held, but also when the relative position of the measuring unit 8 with respect to the original plate table 2 in the Z-axis direction is changed, the first contrast is changed. Therefore, based on the assumption that the position of the measuring unit 8 in the Z-axis direction does not change, it is possible to erroneously determine the abnormal retention of the original plate 1 when the abnormal retention of the original plate 1 is determined based on the change in the first contrast.
FIG. 9 is a graph for showing a change in the contrast of the image of the mark due to a change in the position of the measurement unit 8. When the position of the measurement unit 8 in the Z-axis direction is changed, the first contrast curve and the second contrast curve are changed compared to the graph of FIG. 3. This is because the position of the measuring unit 8 in the Z-axis direction has been changed downward. Therefore, even when the original plate 1 is not abnormally held, it is possible to change the first contrast at the reference position when the position of the measuring unit 8 is changed in the Z-axis direction.
In view of the foregoing, in the third embodiment, the abnormal retention of the original plate 1 is detected in consideration of the change in the first contrast due to the change in the position of the measuring unit 8.
FIG. 10 is a flowchart for explaining a determination method for abnormal retention of an original plate according to the third embodiment. The flowchart of FIG. 10 is different from the flowchart of FIG. 4 in steps S301 to S303. Therefore, the description of other steps is omitted.
In step S301, the control unit 20 obtains the first contrast information obtained in advance from the storage unit in the same manner as in step S201. In addition, the control unit 20 obtains information indicating the relationship between the focus position 11 and the second contrast (second contrast information) obtained in advance from the storage unit. In this case, the control unit 20 measures the fiducial mark 14 while changing the focus position 11 with the original plate 1 being normally held on the original plate table 2, and maintains the second contrast information in the storage unit. In this case, as a format for holding the second contrast information, the second contrast information is held in the storage unit as a discrete data set of the focal position 11 and the second contrast. As a format for maintaining the second contrast information, it is also possible to use information about a function obtained by approximating a discrete data set by a Gaussian function or a higher-order function using the focus position 11 as a variable. When the change in contrast is small, it is also possible to use information about a function obtained by approximating a discrete data set by a linear function using the focal position 11 as a variable. The second contrast information can also be obtained through simulation without actually measuring the contrast. In another case, the external information processing device can maintain the second contrast information. In this case, the control unit 20 obtains the second contrast information from the external information processing device.
In step S302, the control unit 20 uses the first contrast information and the second contrast information to correct the changes in the contrast of the images of the reference mark 14 and the original plate mark 12 at the reference position. First, the control unit 20 obtains the amount of change of the focus position 11 with respect to the master mark 12 by using the first contrast information obtained in step S301 and the first contrast at the reference position obtained in step S106. That is, the control unit 20 obtains the amount of movement in the horizontal axis direction of the curve regarding the master mark 12 shown in FIG. 9 with respect to the curve regarding the master mark 12 shown in FIG. 3.
Next, the control unit 20 obtains the amount of change of the focus position 11 with respect to the reference mark 14 by using the second contrast information obtained in step S301 and the second contrast at the reference position obtained in step S106. That is, the control unit 20 obtains the amount of movement of the curve about the reference mark 14 shown in FIG. 9 in the horizontal axis direction relative to the curve about the reference mark 14 shown in FIG. 3.
Next, the control unit 20 corrects the amount of change in the focus position 11 with respect to the master mark 12 so as to cancel the amount of change in the focus position 11 with respect to the reference mark 14. For example, when the curve regarding the reference mark 14 has been moved to the right (positive direction) on the horizontal axis, the control unit 20 corrects the curve regarding the master mark 12 so as to move the curve to the left (negative direction) on the horizontal axis. Then, the control unit 20 corrects the first contrast at the reference position (Z=0) by using the corrected curve regarding the original plate mark 12.
Then, the control unit 20 corrects the amount of change in the focus position 11 with respect to the reference mark 14 so as to cancel the amount of change in the focus position 11 with respect to the reference mark 14. For example, when the curve on the reference mark 14 has been moved to the right (positive direction) on the horizontal axis, the control unit 20 corrects the curve on the reference mark 14 so as to move the curve to the left (negative direction) on the horizontal axis. Then, the control unit 20 corrects the second contrast at the reference position (Z=0) by using the corrected curve with respect to the reference mark 14.
In step S303, the control unit 20 refers to the second contrast (reference contrast) corrected in step S302 to obtain the amount of change in the first contrast corrected in step S302. Then, the control unit 20 determines whether the amount of change in the first contrast exceeds the allowable range defined in advance. When it is determined that the amount of change in the first contrast is within the allowable range, the control unit 20 ends the process. When it is determined that the amount of change in the first contrast exceeds the allowable range, the control unit 20 advances the process to step S108. In addition, the control unit 20 may refer to the first contrast at the reference position obtained from the first contrast information obtained in advance to obtain the amount of change in the first contrast corrected in step S302.
In step S302, when the position of the measuring unit 8 with respect to the master plate 2 in the Z-axis direction changes greatly, the control unit 20 may determine that the focus is abnormal. For example, the control unit 20 determines whether the amount of change in the focus position 11 with respect to the reference mark 14 is within an allowable range. When the amount of change of the focus position 11 relative to the reference mark 14 exceeds the allowable range, the control unit 20 may also output an error through the user interface to end the processing.
The determination method for abnormal retention of the original plate according to the third embodiment may be used alone, but may also be used in combination with the determination method for abnormal retention of the original plate according to the first or second embodiment. That is, when it is determined that the original plate 1 is being abnormally held on the original plate table 2 after the determination method for the abnormal retention of the original plate according to the first embodiment or the second embodiment is performed, the method for the original plate according to the third embodiment may be performed Determining method of exception retention.
As described above, according to the third embodiment, it is possible to detect abnormal retention of the original plate in a short period of time by determining whether the change in the contrast of the image of the original plate mark is within the allowable range. In addition, a change in the first contrast due to a change in the position of the measurement unit 8 can be considered, and therefore it is possible to suppress erroneous detection of abnormal retention of the original plate.
<Fourth embodiment>
Next, a lithography apparatus according to a fourth embodiment of the present invention will be described. It should be noted that matters not mentioned below can follow the first embodiment to the third embodiment. In the fourth embodiment, an embodiment is described in which, based on a change in the first light amount, information indicating the relationship between the focus position 11 and the first light amount is used to detect abnormal retention of the original plate 1.
Fig. 11 is a view for explaining a lithography apparatus according to a fourth embodiment. The exposure apparatus 100 in the fourth embodiment includes a board 21 on the substrate stage 5 and a light receiving element 22 configured to measure the amount of light inside the substrate stage 5.
FIG. 12 is a view for explaining the substrate stage 5 in the fourth embodiment. The board 21 is arranged on the substrate stage 5, and is provided with a reference mark 24 for light quantity measurement. The light receiving element 22 is arranged inside the substrate stage 5 and below the board 21 and the reference mark 24.
The original plate mark 12 for light quantity measurement is provided in the illuminated area of the original plate 1, and the original plate mark 12 is illuminated by the illumination optical system 6, thereby forming an image 25 of the original plate mark 12 on the substrate side of the projection optical system 3.
In consideration of the imaging magnification of the projection optical system 3, the master mark 12 and the reference mark 24 are designed so that the image 25 of the master mark 12 and the reference mark 24 have the same shape. Therefore, when the image 25 of the original plate mark 12 and the reference mark 24 are arranged in mutually conjugate positions, the image 25 of the original plate mark 12 and the reference mark 24 are superimposed on each other, and light from the image 25 of the original plate mark 12 passes through the reference mark 24 The opening part of the transmission. The light amount of the transmitted light 23 is measured by the light receiving element 22 arranged under the board 21. When the fiducial mark 24 becomes closer to the focal position of the image 25 forming the master mark 12, the amount of light transmitted therethrough increases, and the amount of light measured by the light receiving element 22 increases. In the fourth embodiment, the image 25 and the reference mark 24 of the master mark 12 are set to have the same shape, but the image 25 and the reference mark 24 of the master mark 12 may have different shapes, as long as they can be obtained from these shapes. The positional relationship between the plate 21 on the substrate stage and the original plate 1 is sufficient.
In addition, the substrate stage 5 is configured to be movable, and therefore it is possible to move the board 21, the reference mark 24, and the light receiving element 22 arranged on/in the substrate stage 5. Therefore, the control unit 20 can measure the amount of light from the light receiving element 22 while driving the substrate stage 5, and can detect the focal position based on the measured amount of light.
The processing for detecting the focus position will now be described. In the process for detecting the focus position, the reference focus position (hereinafter referred to as "reference position") is determined based on the amount of light measured by the light receiving element 22. First, the control unit 20 obtains the light amount of the light 23 measured by the light receiving element 22 while driving the substrate stage 5 in the Z-axis direction. Then, the control unit 20 controls the substrate stage 5 by setting the reference position of the substrate stage 5 to a position where the obtained light amount is maximized. The control unit 20 also sets the light amount of the light 23 measured at the reference position as the reference light amount.
The amount of light measured by the light receiving element 22 will now be described. FIG. 13 is a graph for showing the relationship between the position of the substrate stage 5 in the Z-axis direction and the amount of light measured by the light receiving element 22. In the graph of FIG. 13, the vertical axis indicates the amount of light measured by the light receiving element 22, and the horizontal axis indicates the position of the substrate stage 5 in the Z-axis direction. The reference position of the substrate stage 5 is obtained as the position where the amount of light on the substrate stage 5 is maximized. In the graph of FIG. 13, the reference position is defined as the origin of the horizontal axis (Z=0 (micrometer)). In the case of the contrast in the first embodiment, two curves of the first contrast and the second contrast are obtained. However, in the fourth embodiment, the light amount of the light 23 transmitted through the opening portion of the reference mark 24 is set as the vertical axis, and thus a curve of the light amount is obtained.
In this case, by holding the reference position in the storage unit, the control unit 20 can obtain the reference position without measuring the mark every time the original plate 1 is held on the original plate table 2. When there are multiple original plates 1, the imaging position can be measured for each of the multiple original plates 1 to maintain a different imaging position for each of the original plates 1. The identifier is assigned to each original plate 1 of the plurality of original plates 1, and the control unit 20 obtains the corresponding reference position of the plurality of original plates 1 by holding the identifier of the original plate 1 together with the reference position.
Next, the determination method for the abnormality retention of the original plate 1 is described. As shown in FIG. 5, when the foreign matter 16 is sandwiched between the original plate 1 and the original plate table 2 (suction pad 15) so that the position of the original plate 1 is shifted in the upward direction (the positive direction of the Z axis), the original plate mark 12 is formed The focus position of the image 25 is also shifted. In that case, the entire curve is moved in the horizontal axis direction without changing the shape of the curve in FIG. 13. Therefore, by using the amount of change in the light amount at the reference position (Z=0) and the information (light amount information) indicating the relationship between the focus position and the light amount, the amount of movement of the entire graph in the horizontal axis direction can be obtained. In short, the amount of change in the focal position relative to the image 25 of the master mark 12 can be obtained. When the obtained change amount of the focus position exceeds the allowable range defined in advance, it may be determined that the original plate 1 is being abnormally held on the original plate table 2.
FIG. 14 is a flowchart for explaining a determination method for abnormal retention of the original plate 1 according to the fourth embodiment. The flowchart of FIG. 14 is different from the flowchart of FIG. 4 in steps S401 to S405. Therefore, the description of other steps is omitted.
In step S401, the control unit 20 controls the substrate stage 5 and the light receiving element 22 to perform focus measurement processing. That is, the control unit 20 drives the substrate stage 5 to a position where the light amount of the light 23 measured by the light receiving element 22 is maximized, thereby obtaining the reference position.
In step S402, the control unit 20 controls the substrate stage 5 to move the position of the substrate stage 5 in the Z-axis direction to the reference position obtained in step S103.
In step S403, the control unit 20 obtains the light quantity information obtained in advance from the storage unit. In this case, the control unit 20 changes the position of the substrate table 5 in the Z-axis direction while the original plate 1 is normally held on the original plate table 2, and measures the amount of light through the light receiving element 22, and stores it in the storage unit Keep light quantity information.
In step S404, the control unit 20 causes the light receiving element 22 to measure the light amount of the light 23, and obtain the light amount at the reference position.
In step S405, the control unit 20 obtains the amount of change in the focus position of the image 25 forming the master mark 12 by using the light amount information obtained in step S403 and the light amount at the reference position obtained in step S404. That is, the control unit 20 obtains the amount of movement on the horizontal axis of the curve with respect to the light amount shown in FIG. 13. Then, the control unit 20 determines whether the amount of change in the focus position of the image 25 forming the master mark 12 exceeds the allowable range defined in advance, and when it is determined that the amount of change is within the allowable range, the processing ends. When it is determined that the amount of change exceeds the allowable range, the control unit 20 advances the process to step S108.
As described above, according to the fourth embodiment, it is possible to determine whether the change in the focus position of the image 25 forming the master mark 12 is within an allowable range by using the relationship between the focus position and the amount of light to detect in a shorter period of time The exception of the original version remains.
(Method of manufacturing items)
The method of manufacturing an article according to the present invention is suitable for manufacturing an article, for example, a semiconductor device, a magnetic storage medium, a liquid crystal display device, or other such devices. The manufacturing method includes exposing a substrate to which a photosensitizer is applied by using an exposure device (forming a pattern on the substrate), and developing the exposed substrate (processing the substrate). The manufacturing method may further include performing oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, cutting, bonding, packaging, and other such known processes. Compared with the related art, the method of manufacturing an article according to the present invention is advantageous in at least one of the performance, quality, productivity, and production cost of the article.
The exemplary embodiments of the present invention have been described above, but it should be understood that the present invention is not limited to those embodiments, and various modifications and changes can be made thereto without departing from the spirit of the present invention. The exposure apparatus has been described as an example of the lithography apparatus, but the present invention is not limited to this.
As an example of the lithography apparatus, an imprint apparatus may be used, which is configured to form a pattern of an imprint material on a substrate by using a mold (pattern or template) having an uneven pattern. As another example of the lithography apparatus, a planarization apparatus configured to perform molding can be used in order to planarize the composition on the substrate by using a mold (flat template) having a flat portion without an uneven pattern. As yet another example of the lithography device, a drawing device or other such device configured to perform drawing on a substrate to form a pattern on the substrate using a charged particle beam (for example, an electron beam or an ion beam) through a charged particle optical system can be used. Class equipment.
The first to fourth embodiments can be implemented not only individually, but also in any combination of the first to fourth embodiments.
According to at least one embodiment of the present invention, it is possible to provide a lithography apparatus, a determination method, and a method of manufacturing an article capable of detecting abnormal retention of an original plate in a short period of time.
Although the present invention has been described with reference to the exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following patent applications should be given the broadest interpretation so as to include all such modifications and equivalent structures and functions.
