以下，參照所附附圖詳細地說明實施方式。需要說明的是，以下的實施方式並不限定申請專利範圍的技術方案。在實施方式中記載有多個特徵，但該多個特徵的全部未必是發明所必須的特徵，另外，多個特徵也可以任意組合。而且，在所附附圖中，對相同或者同樣的結構標注相同的參照編號，省略重複的說明。
＜第1實施方式＞
說明本發明的第1實施方式的曝光裝置100。曝光裝置100是用於製造半導體器件、液晶顯示器等的光刻裝置。本實施方式的曝光裝置100是藉由步進方式或者掃描方式將原版(掩模、中間掩模)的圖案像投影到基板上，由此曝光基板，將原版的圖案轉印到基板的投影曝光裝置。以下，作為曝光裝置100，例示說明利用狹縫光掃描曝光基板的掃描方式的曝光裝置。
[曝光裝置的結構]
圖1是表示第1實施方式的曝光裝置100的結構的概略圖。本實施方式的曝光裝置100可包括照明光學系統10、保持原版M並可移動的原版載置台20、投影光學系統30、保持基板W並可移動的基板載置台40、測量部50、控制部60。控制部60由具有例如CPU、記憶體等的計算機構成，控制基板W的曝光處理(曝光裝置100的各部分)。原版M是由鉻等遮光材料形成應轉印到基板W上的精細圖案(例如電路圖案)而成的玻璃製原版。另外，作為基板W，能夠使用半導體晶片、玻璃板等。
為了在原版上得到所期望的照度分佈，照明光學系統10將來自光源(未圖示)的光整形為例如在Y軸方向上長的圓弧狀的光，利用整形後的光(狹縫光)以大致均勻的照度對原版M進行照明。光源能夠使用水銀燈等。原版M和基板W分別被原版載置台20和基板載置台40保持，配置於經由投影光學系統30在光學上大致共軛的位置(投影光學系統30的物面和像面的位置)。投影光學系統30具有預定的投影倍率，利用多個反射鏡反射掩模1的圖案像並投影到基板2。另外，沿與投影光學系統30的物面平行的方向(例如X軸方向)以與投影光學系統30的投影倍率相應的速度比對掩模載置台20和基板載置台40相對地同步掃描。由此，能夠進行基板W的掃描曝光，將形成於原版M的圖案轉印於基板W(具體而言，基板上的抗蝕劑(感光劑))。
例如，如圖1所示，投影光學系統30能夠構成為包括梯形鏡31、凹面鏡32以及凸面鏡33。從照明光學系統10射出並通過原版M的圖案光EL(以下有時稱為“曝光的光EL”)被梯形鏡31的上表面折彎光路，向凹面鏡32的反射面的上部入射。在凹面鏡32的反射面的上部反射的曝光的光EL在凸面鏡33的反射面反射，向凹面鏡32的反射面的下部入射。在凹面鏡32的反射面的下部反射的曝光的光EL被梯形鏡31的下表面折彎光路，向基板W入射。在像這樣構成的投影光學系統30中，凸面鏡33的反射面成為光瞳。另外，投影光學系統30為了不產生由原版M與基板W在光軸方向(Z方向)上的位置變動引起的倍率誤差，在原版M側和基板W側，也就是物面側、像面側都為遠心光學系統。
另外，在投影光學系統30能夠設有用於驅動各光學元件的致動器。具體而言，能夠設有用於驅動梯形鏡31的致動器34、用於驅動凹面鏡32的致動器35以及用於驅動凸面鏡33的致動器36。各致動器34~36能夠用於降低各光學元件的變動(振動)。
在此，致動器35較佳是針對凹面鏡32配置於至少3處。致動器35，例如能夠使用電磁致動器等由固定部和可動部非接觸地構成的致動器，在該情況下，能夠避免由凹面鏡32的支承部的干涉引起的凹面鏡32的變形。另外，在該情況下，期望的是將作為熱源的線圈安裝於凹面鏡32的支承部側，將作為非熱源的磁鐵安裝於凹面鏡32。電磁致動器，既可以應用使用了電磁鐵的吸引力的電磁致動器，也可以應用音圈型線性馬達。在使用音圈型線性馬達的情況下，除驅動方向之外的其它分量的力變小，因此更加適合。關於設於梯形鏡31的致動器34以及設於凸面鏡33的致動器35也是同樣的，較佳是使用電磁致動器或者將熱源遠離光學元件地配置。另外，作為致動器34~36，若使用由偏移機構支承驅動方向以外的部件，則也能夠使用壓電型或螺紋進給機構。
在這樣的曝光裝置100中，通常而言，能夠設置使來自設置地面的干擾振動衰減的除振裝置(未圖示)，但難以利用該除振裝置使干擾振動消失。因此，在基板W的掃描曝光中，有時干擾振動向曝光裝置100的各部分(特別是投影光學系統30)傳遞。另外，在基板W的掃描曝光中，原版載置台20和基板載置台40移動，因此由該移動產生的振動也有時向投影光學系統30傳遞。在這些情況下，投影光學系統30所包含的各光學元件(例如梯形鏡31、凹面鏡32、凸面鏡33)發生振動，會產生曝光的光EL的位置變動(振動、像偏)。其結果，可能難以將原版M的圖案像精度良好地投影到基板上，即，難以將原版M的圖案精度良好地轉印到基板上。因此，本實施方式的曝光裝置100具有用於測量投影光學系統30的光學特性的測量部50，基於測量部50的測量結果修正曝光的光EL在基板上的照射位置。
測量部50將作為平行光(准直光)的測量光ML投射到投影光學系統內，基於經過了曝光的光EL要經由的投影光學系統內的光學元件的測量光ML，測量投影光學系統30的光學特性、即投影光學系統30的內部狀態。具體而言，測量部50具有：投光部51，將測量光ML(光束)投射到投影光學系統30內；以及受光部52，接受通過投影光學系統30而射出的測量光ML。在投影光學系統30內，測量光ML與曝光的光EL同樣地，按照梯形鏡31的上表面、凹面鏡32的反射面的上部、凸面鏡33、凹面鏡32的反射面的下部、梯形鏡31的下表面的順序反射，並從投影光學系統30射出。
投光部51例如能夠包括光源51a和反射鏡51b。光源51a具有氣體雷射器、半導體雷射器、LED等發光元件和准直儀透鏡，將測量光ML作為平行光(准直光)射出。反射鏡51b將從光源51a射出的測量光ML的光路折彎，將測量光ML引導到投影光學系統30內。投光部51(光源51a、反射鏡51b)在原版載置台20(原版M)與投影光學系統30之間安裝於投影光學系統30。另外，投光部51構成為利用配置於原版M與投影光學系統30之間的反射鏡51b，使測量光ML與投影光學系統30的光軸平行。藉由像這樣將反射鏡51b配置於原版M的下方側，能夠使測量光ML始終入射到投影光學系統30內。
受光部52例如能夠包括受光元件52a和反射鏡52b。反射鏡52b使在投影光學系統30內通過而從投影光學系統30射出的測量光ML的光路在基板W的前方折彎，將測量光ML向受光元件52a引導。受光元件52a接受測量光ML，輸出與測量光ML的受光位置相應的訊號值。在本實施方式的情況下，受光元件52a具有接受測量光ML的受光面53，輸出與測量光ML在該受光面53處的受光位置相應的訊號值。受光元件52a的具體的結構將在以後敘述。受光部52(受光元件52a、反射鏡52b)在基板載置台40(基板W)與投影光學系統30之間安裝於投影光學系統30。在本實施方式的情況下，投影光學系統30為兩側遠心光學系統，測量光ML與投影光學系統30的光軸平行地入射，因此在投影光學系統30的基板W側，測量光ML也與光軸平行地射出。另外，由於使用平行光作為測量光ML，因此關於配置受光元件52a(受光面53)的位置，不需要考慮投影光學系統30的成像位置。因而，本實施方式的受光元件52a(受光面53)也可以配置在與投影光學系統30的成像位置不同的位置。
在此，在使用半導體雷射器或者LED作為投光部51的光源51a的情況下，能夠使測量光ML快速地閃爍，因此能夠射出具有特定的頻率的測量光ML。在該情況下，藉由使來自受光部52的受光元件52a的訊號的輸出頻率與自光源51a射出的測量光ML的頻率同步，就能夠降低雜訊分量。即，能夠得到著眼於特定的頻率分量的受光元件52a的訊號值。
如上所述構成的測量部50能夠針對曝光的光EL設有多個。圖2是從上方(原版載置台20側)觀察投影光學系統30而得到的圖，圖示了曝光的光EL的截面(照明區域11)和測量部50的投光部51(光源51a、反射鏡51b)。多個測量部50能夠在曝光的光EL的周圍的多處配置，以使多個測量光ML分別投射到投影光學系統30內。在圖2所示的例子中，設有4個測量部50，該4個測量部50在曝光的光EL(照明區域11)的周圍配置成以橫穿曝光的光EL的光軸(Z軸方向)且與掃描方向(X方向)平行的直線為軸線的線對稱。藉由像這樣設置多個測量部50，不僅能夠測量投影光學系統30內的測量光ML的位置變動(光軸偏移)，也能夠測量投影光學系統30的倍率分量。
需要說明的是，測量光ML的位置變動是指，由於藉由投影光學系統30，測量光ML的光軸從基準位置向平移方向(XY方向)和旋轉方向(繞Z軸的旋轉方向)變動(偏移)。另外，基準位置能夠是根據向投影光學系統30入射的入射位置而應從投影光學系統30射出的測量光ML的光軸位置。
接下來，說明使用了受光部52的受光元件52a的投影光學系統30的光學特性的測量方法。受光元件52a，例如能夠使用光電二極體等光強度感測器(光電轉換感測器)。在本實施方式的情況下，受光元件52a能夠包括構成為能夠在受光面53的多個部分區域中的各部分區域檢測光強度的多個光電二極體。在以下，說明受光元件52a使用4個光電二極體(也被稱為4象限光電二極體)的例子。
圖3是表示本實施方式的受光元件52a的受光面53的圖。在本實施方式的情況下，受光面53如圖1所示是YZ面，但在圖3中，為了容易理解說明，對不使用受光部52的反射鏡52b而將受光面53設為XY面的情況進行說明。另外，在圖3所示的例子中，受光元件52a由4象限光電二極體構成，受光面53具有能夠獨立地檢測光強度的4個部分區域53a~53d。即，作為受光元件52a的4象限光電二極體被構成為獨立地輸出與分別入射到部分區域53a~53d的光的光量相應的訊號值(例如電流值)。另外，從4象限光電二極體獨立地輸出的訊號值(電流值)能夠與電流電壓轉換器連接而轉換為電壓值。
例如，如圖3那樣，考慮測量光ML入射到受光面53的中央位置(4象限光電二極體的中央位置)的情況。在該情況下，從4象限光電二極體部分別得到4個電壓值A、B、C、D。該電壓值A、B、C、D依賴於測量光EL的光量、光電二極體靈敏度、電流電壓轉換器增益等。而且，這些電壓值根據測量光EL的位置變動而變化，其變化量依賴於測量光EL的直徑、形狀(光量分佈)。例如，若測量光EL的入射位置(受光位置)從圖3的狀態起向右方向(＋X方向)變動，則在受光面53的部分區域53b~53c受光量增加，在受光面53的部分區域53a、53d受光量減少。也就是說，電壓值B、C增加，電壓值A、D減少。另一方面，若測量光EL的入射位置(受光位置)從圖3的狀態起向上方向(＋Y方向)移動，則在受光面53的部分區域53c~53d受光量增加，在受光面53的部分區域53a~53b受光量減少。也就是說，電壓值C、D增加，電壓值A、B減少。
因而，控制部60能夠基於由4象限光電二極體得到的電壓值A~D，求出以受光面53的中央位置為基準時的測量光ML的受光位置偏移。測量光ML在受光面53的受光位置偏移與測量光ML在投影光學系統30中的光軸偏移(X、Y)成比例，能夠利用以下的式子(1)~(2)運算。需要說明的是，上述運算在本實施方式中能夠由控制部60進行，但當在測量部50設有CPU等處理部的情況下，也可以由該處理部進行。
式(1)的係數kx是用於將測量光ML在受光面53的受光位置偏移(X方向)變換為測量光ML在投影光學系統30中的光軸偏移(X方向)的變換係數(比例係數)。同樣地，式(2)的係數ky是用於將測量光ML在受光面53的受光位置偏移(Y方向)變換為測量光ML在投影光學系統30中的光軸偏移(Y方向)的變換係數(比例係數)。係數kx和係數ky例如能夠藉由事先的實驗、模擬等求出。其中一例，藉由一邊變更測量光ML向投影光學系統30的入射位置，使測量光ML在投影光學系統30中的光軸發生偏移，一邊逐次測量測量光ML在受光面53的受光位置偏移的變化，從而能夠得到係數kx和係數ky。
另外，在測量光ML的直徑比4象限光電二極體的受光面53大的情況、或小到無法忽略4象限光電二極體的接縫區域(無法檢測光強度的區域)的寬度的程度的情況等下，也可以進行電壓值A~D的歸一化。具體而言，當多個部分區域53a~53d中的受光量的總和由於測量光ML在受光面53的受光位置偏移而發生變動的情況下，如以下的式(3)~(4)所示，藉由以該受光量的總和進行歸一化，能夠主要謀求線性的改善。需要說明的是，式(3)~(4)的係數kx’和係數ky’是用於將測量光ML在受光面53的受光位置偏移變換為測量光ML在投影光學系統30中的光軸偏移的變換係數(比例係數)。
在此，測量光ML在投影光學系統30內經過了曝光的光EL所經由的多個光學元件。因此，能夠使由測量光ML在受光面53的受光位置偏移運算得到的測量光ML在投影光學系統30中的光軸偏移與曝光的光EL在基板上的位置變動(像偏)相對應。也就是說，控制部60藉由進行上述運算，能夠基於測量光ML在受光元件52a(受光面53)的受光位置，對曝光的光EL在投影光學系統30中的位置變動進行估計。然後，能夠根據估計的曝光的光EL的位置變動，修正曝光的光EL在基板上的照射位置。在本實施方式的情況下，能夠與基板W的掃描曝光並行地進行曝光的光EL在基板上的照射位置的修正。
像這樣，在本實施方式的曝光裝置100中，藉由使用為平行光的測量光ML，能夠應用多個光電二極體(例如4象限光電二極體)作為受光元件52a。也就是說，在本實施方式的結構中，與如專利文獻1所記載的那樣使用由CMOS感測器等光檢測元件和受光光學系統構成的圖像感測器來檢測標記的投影像的以往的結構相比，能夠利用簡單的結構測量投影光學系統30的光學特性。另外，在本實施方式的結構中，由於在投影光學系統30的光學特性的測量中不使用標記的投影像，因此能夠不考慮投影光學系統30的成像位置而任意地配置受光元件52a的受光面53。即，能夠在與投影光學系統30的成像位置不同的位置配置受光面53。因此，在裝置成本、裝置的設計自由度的點上有利。另外，在本實施方式的結構中使用光電二極體，與運算標記的投影像的位置的以往的結構相比，運算規模較小，因此能夠縮短投影光學系統30的光學特性的測量週期。也就是說，在以往的結構中，離散地測量投影光學系統30的光學特性，相對於此，在本實施方式的結構中，能夠連續地測量投影光學系統30的光學特性。
[曝光的光的照射位置的修正]
投影光學系統30的光學特性的變化、即曝光的光EL在投影光學系統30中的位置變動例如可能由投影光學系統30的光學元件的振動、投影光學系統30內的環境波動(空氣波動)引起。在曝光的光EL的位置變動因投影光學系統30的光學元件(梯形鏡31、凹面鏡32、凸面鏡33)引起的情況下，控制部60藉由由致動器34~36驅動光學元件，來進行曝光的光EL在基板上的照射位置的修正。另一方面，在曝光的光EL的位置變動因投影光學系統30內的環境波動引起的情況下，控制部60藉由調整投影光學系統30內的溫度和/或壓力，進行曝光的光EL在基板上的照射位置的修正。在本實施方式的情況下，如圖1所示，能夠設有用於調整投影光學系統30內的溫度和/或壓力的調整部71。
對基於測量部50的測量結果進行曝光的光EL在基板上的照射位置的修正的方法的一例進行說明。如上所述，曝光的光EL在投影光學系統30中的位置變動可能由投影光學系統30的光學元件的振動和/或投影光學系統30內的環境波動引起。例如，在構成投影光學系統30的多個光學元件(例如梯形鏡31、凹面鏡32、凸面鏡33)中，重量互不相同，因此固有振動頻率(振動頻率)也互不相同。因而，只要調查測量光ML在受光元件52a的受光位置的變動(振動)的頻率分量，就能夠確定對測量光ML的受光位置的變動、即曝光的光EL的位置變動造成影響的光學元件。
在本實施方式的情況下，控制部60使用快速傅裡葉變換等，進行測量光ML在受光元件52a中的受光位置的變動(振動)的頻率分析(即，分解為多個頻率分量)。然後，在作為頻率分析的結果，得到與例如凹面鏡32的固有振動頻率相對應的頻率分量的情況下，控制部60向致動器35發出指令，使凹面鏡32的振動衰減(阻尼)。作為一例，控制部60藉由對以受光元件52a(受光面53)的中心位置為基準時的測量光ML的受光位置偏移的方向和大小進行座標變換、增益調整以及濾波等，求出致動器35的指令值。藉由將這樣求得的指令值提供給致動器35，能夠降低凹面鏡32的振動。同樣地，在得到與梯形鏡31和/或凸面鏡33的固有振動頻率相對應的頻率分量的情況下，控制部60向致動器34、36提供指令值，使梯形鏡31和/或凸面鏡33的振動衰減。
另外，在作為頻率分析的結果，得到比投影光學系統30的各光學元件的固有振動頻率低的頻率分量的情況下，考慮由於投影光學系統30內的環境波動(溫度、壓力)引起的折射率變動的影響。在該情況下，控制部60藉由利用調整部71調整投影光學系統30內的溫度和/或壓力，能夠降低測量光ML的受光位置的變動、即曝光的光EL的位置變動。例如，控制部60藉由將變更投影光學系統30內的環境的控制參數的指令值提供給調整部71，能夠降低曝光的光EL的位置變動，進行曝光的光EL在基板上的照射位置的修正。
如圖2所示，在設置多個測量部50的結構中，能夠部分地檢測曝光的光EL的位置變動。在該情況下，能夠在發生曝光的光EL的位置變動的部分，選擇性地進行曝光的光EL的照射位置的修正。另外，在圖2所示的結構中，不僅能夠測量平移方向、旋轉方向，還能夠測量投影光學系統的倍率分量，因此還能夠控制各致動器34~36和調整部71，修正投影光學系統30的倍率分量。
在此，如上所述基於在受光元件52a中的檢測結果來降低投影光學系統30的各光學元件的振動的控制環是位置回饋。因此，為了進一步提高各光學元件的振動的控制性和穩定性，也可以進一步施加加速度回饋。例如，也可以在投影光學系統30的各光學元件設置加速度感測器，進一步施加基於由加速度感測器檢測到的光學元件的加速度來降低該光學元件的振動的加速度回饋。在圖1所示的例子中，針對投影光學系統30中的多個光學元件(梯形鏡31、凹面鏡32、凸面鏡33)分別設有加速度感測器37a~37c。
[曝光的光的變動的估計]
接下來，說明測量部50中的受光元件52a的設置位置。在曝光的光EL的從投影光學系統30到基板W的光程長度與測量光ML的從投影光學系統30到受光元件52a(受光面53)的光程長度大致相同的情況下，也可以認為測量光ML的變動(振動)與曝光的光EL的變動(振動)大致相同。在該情況下，控制部60能夠視為產生了與由受光元件52a得到的測量光ML的變動(振動)大致相同的曝光的光EL的變動(振動)，而控制致動器34-36。然而，在投影光學系統30與基板W(基板載置台40)之間的區域配置有用於曝光的各種各樣的構成物，有時難以將受光元件52a配置於所期望的場所。
在這樣無法將自投影光學系統30的光程長度對於曝光的光EL和測量光ML配置為大致相同的情況下，較佳是根據由受光元件52a得到的測量光ML的變動量(受光位置偏移量)估計曝光的光EL的變動量(照射位置在基板上的偏移量)。例如，假設由於投影光學系統30的各光學元件發生振動，而使曝光的光EL和測量光ML彎曲了相同角度的情況。在該情況下，可能因彎曲的測量光ML到達受光元件52a為止的光程長度與彎曲的曝光的光到達基板W為止的光程長度之差引起測量光ML在受光元件52a上(受光面53上)的變動量與曝光的光EL在基板上的變動量不同。然而，這些光程長度能夠設為已知，因此能夠使用這些光程長度比作為換算係數，將測量光ML在受光元件52a上的變動量換算為曝光的光EL在基板上的變動量。
在此，投影光學系統30中的多個光學元件(梯形鏡31、凹面鏡32、凸面鏡33)通常而言配置於曝光的光EL的光程長度互不相同的部位。也就是說，曝光的光EL的直到基板W為止的光程長度能夠在多個光學元件中互不相同。因此，若使用在多個光學元件中通用地設定的換算係數，將測量光ML在受光元件52a上的變動量簡單地換算為曝光的光EL在基板上的變動量，則實際的曝光的光EL在基板上的變動量有時會產生誤差。因而，較佳是對每個光學元件設定換算係數。
在本實施方式的情況下，對於各光學元件，到受光元件52a為止的光路量以及到基板W為止的光程長度是已知的，因此，基於這些光程長度比按每個光學元件(每個固有頻率)設定換算係數。控制部60使用快速傅裡葉變換等，將由受光元件52a得到的測量光ML的變動量的時間軸資料變換為頻率軸資料，進行頻率分析，基於由該分析結果得到的頻率分量，確定起因於測量光ML的振動的光學元件。如上所述，投影光學系統30中的多個光學元件具有互不相同的固有振動頻率(振動頻率)，因此能夠根據由頻率分析的結果得到的頻率分量確定由哪個光學元件的振動引起測量光ML振動。因而，控制部60能夠選擇與確定出的光學元件相關聯地設定的換算係數，將測量光ML在受光元件52a上的變動量換算為曝光的光EL在基板上的變動量。由此，能夠降低在實際的曝光的光EL在基板上的變動量中產生的誤差。
另外，在投影光學系統30的各光學元件中，對於曝光的光EL和測量光ML而言存在反射或者透過的場所不同的情況、或者為了不使基板上的抗蝕劑感光而對於曝光的光EL和測量光ML而言存在波長不同的情況。在該情況下，對於曝光的光EL和測量光ML而言各光學元件的振動的影響度可能不同，因此在將測量光ML在受光元件52a上的變動量換算為曝光的光EL在基板上的變動量時有時會產生誤差。因而，藉由實驗、模擬等求得曝光的光EL和測量光ML的各光學元件的振動的影響度之差(以下有時稱為“影響差”)，修正換算係數以降低該差為佳。例如，使用事先設定好的換算係數，將測量光ML在受光元件52a上的變動量換算為曝光的光EL在基板上的變動量，基於得到的曝光的光EL的變動量，一邊修正曝光的光EL在基板上的照射位置一邊進行基板W的掃描曝光。在藉由該掃描曝光在基板上實際形成的圖案產生像偏、曝光不均等誤差(例如與基底圖案的重合誤差)的情況下，該誤差能夠相當於曝光的光EL與測量光ML的影響度差。因而，能夠修正換算係數，以降低該誤差。
如上所述，測量光ML在受光元件52a上的變動量有時因投影光學系統30內的環境波動(空氣波動)而產生。測量光ML和曝光的光EL經由相同的投影光學系統30內的空間，因此測量光ML受到與曝光的光EL大致相同的環境波動的影響。因而，能夠基於測量光ML在受光元件52a上的變動量，估計因投影光學系統30內的環境波動引起的曝光的光EL在基板上的變動量。
例如，在測量光ML在受光元件52a上的變動量的頻率分析的結果中，上述投影光學系統30的光學元件的固有振動頻率以外的頻率的至少一部分能夠視為由投影光學系統30內的環境波動造成的影響量。控制部60既可以藉由利用調整部71調整投影光學系統30內的溫度和/或壓力來修正因該環境波動引起的曝光的光EL的變動量，也可以藉由利用致動器34~36驅動投影光學系統30的各光學元件來進行修正。需要說明的是，本實施方式的測量部50也能夠用作監測掃描曝光中的投影光學系統30內的環境波動對曝光的光EL的影響度的感測器。因此，也可以有效利用於開發用於降低該環境波動的硬體和裝置驅動軟體。
[測量精度的提高方法]
為了在測量部50中提高測量光ML的變動量的測量精度而更高精度地進行曝光的光EL在基板上的照射位置的修正，提高測量光ML在受光元件52a中的檢測解析度為佳。以下，對用於提高該檢測解析度的幾種方法進行說明。
第1方法，是盡可能地降低雜訊。在從受光元件52a輸出的訊號值中，除包含基於測量光ML的本來的訊號值之外，還包含由除測量光ML之外的干擾光引起的雜訊分量、由電流電壓轉換器等產生的電雜訊分量等。因此，若盡可能地降低這些雜訊分量，則能夠提高S/N比，提高檢測解析度。降低干擾光的方法，有將受光元件52a的周邊遮光、或使用波長濾波器阻斷除測量光ML之外的干擾光的方法。另外，降低電雜訊分量的方法，有使所使用的電流電壓轉換器盡可能低雜訊、或使受光元件52a的周邊相對於周邊電磁場遮罩的方法。另外，電流電壓轉換器的雜訊和增益彼此相關，因此考慮兩者的兼顧來設定為佳。
第2方法，是盡可能地減小入射到受光元件52a的測量光ML的直徑。測量光ML的直徑越小，光量分佈越是成為尖銳的形狀，因此即使是相同的測量光ML的變動量，也能夠使由4象限光電二極體(各部分區域53a~53d)得到的訊號值較大程度地變化。這意味著靈敏度提高，由於S/N比的信號側提高，因此能夠檢測出更小的位置變動。
第3方法，有調整測量光ML的光強度(光量)，以使從受光元件52a(4象限光電二極體)輸出的電壓值A~D接近於電流電壓轉換器的最大輸出的方法。這也具有增大因測量光ML的位置變動引起的受光元件52a的電壓變動(信號)的效果，因此能夠提高受光元件52a的靈敏度。例如，藉由將從光源51a輸出的測量光ML的光強度(光量)設定得比所需光強度大，變更配置於光源51a與受光元件52a之間的ND濾光器的透光率，就能夠調整測量光ML的光強度。
第4方法，有藉由使用高解析度的測量系統進行測量，而能夠測量微小電壓的方法。或者，藉由使用動作放大器，放大上述式(1)~(4)中的(A-C)和(B-D)的信號，從而能夠測量從受光元件52a輸出的電壓值A、B、C、D所包含的微小電壓分量，也能夠謀求解析度提高。
但是，通常而言，動作放大器的輸出有限，因此設定為差動分量(A-C)、(B-D)的絕對值盡可能小且各電壓值A、B、C、D各自的平均電壓相同為佳。例如，在使用最大輸出為10[V]的差動放大器的情況下，在電壓值A的平均值為8[V]、電壓值C的平均值為7[V]的情況下，差動放大器的放大倍率最大只能得到10倍。另一方面，在電壓值A的平均值為8.0[V]、電壓值C的平均值為7.9[V]的情況下，能夠使動作放大器的放大倍率最大為100倍，因此能夠將更微小的電壓分量也進行放大來檢測。
為了能夠同樣地調整上述各電壓值A、B、C、D各自的平均電壓電平，較佳是使測量光ML的光強度分佈相對於光軸對稱。另外，較佳是具備調整測量光ML與受光元件52a的相對位置的機構。在受光元件52a中，由於其固定部的熱變形等，相對於投影光學系統30的位置有可能發生變動。由此，在與接受的測量光ML的光軸正交的面方向(正交的2個方向)，在曝光裝置100設置用於調整受光元件52a相對於投影光學系統30的位置和/或姿態的調整機構為佳。
另外，在測量部50中，對於投光部51的光源51a而言，測量光ML的出射方向、出射位置有時會發生變動。另外，與受光元件52a同樣地，對於光源51a而言也是，由於其固定部的熱變形等，測量光ML的出射方向、出射位置有時會發生變動。像這樣，若在光源51a中，測量光ML的出射方向、出射位置發生變動，則可能難以使測量光ML以所期望的入射角度和入射位置入射到投影光學系統30。其結果，根據測量光ML在受光元件52a上的變動量換算的曝光的光EL在基板上的變動量可能產生因測量部50本身引起的誤差。由此，在曝光裝置100設置如下這樣的調整機構為佳：該調整機構用於調整光源51a相對於投影光學系統30的位置和/或姿態，以變更從光源51a出射的測量光ML的位置和/或傾斜度。
需要說明的是，在光源51a和/或受光元件52a的位置、姿態的調整過程中，是無法測量測量光ML的變動量的狀態。因此，較佳是在基板W的掃描曝光中，不進行光源51a和/或受光元件52a的位置、姿態的調整，而是例如在原版M、基板W的更換處理中、原版M與基板W的對準處理中等除掃描曝光之外的處理中進行。
在此，在本實施方式中，將投影光學系統30作為反射光學系統進行了說明，但也可以設為折射光學系統、反射折射光學系統。另外，圖2所示的照明區域11(曝光的光EL的截面)的形狀可能根據要應用的光學系統而不同，但藉由在照明區域11的周邊(外周)配置反射鏡51b，得到與在照明區域11的附近配置光源51a同樣的效果。另外，在本實施方式中，使用4象限光電二極體作為受光元件52a，但也可以使用多個不是象限(分割)類型的光電二極體，利用棱鏡、分束器進行光學分割。而且，在本實施方式中，說明了配置多個測量部50(受光元件52a)的例子，但也可以僅配置1個測量部50(受光元件52a)，僅測量測量光ML在平移方向的變動量。
＜第2實施方式＞
說明本發明的第2實施方式。本實施方式基本上繼承了第1實施方式，因此以下對與第1實施方式不同的態樣進行說明。在第1實施方式中，藉由利用致動器34~36驅動投影光學系統30的各光學元件和/或藉由利用調整部71調整投影光學系統30內的環境(溫度、壓力)，進行了曝光的光EL在基板上的照射位置的修正。在本實施方式中，說明藉由變更原版M與基板W的相對位置，來進行曝光的光EL在基板上的照射位置的修正的例子。
在本實施方式的情況下，控制部60根據測量光ML在受光元件52a上的變動量估計曝光的光EL在基板上的變動量。具體而言，使用事先設定的換算係數，將測量光ML在受光元件52a上的變動量換算為曝光的光EL在基板上的變動量。然後，控制部60驅動基板載置台40並控制(調整)基板W的位置，以修正所估計的曝光的光EL的變動量。
例如，對從受光元件52a輸出的訊號值進行平均化、或者提取旋轉分量而對照明區域11進行移動平均，同時進行座標變換、增益調整以及濾波等，從而求出用於修正曝光的光EL的變動量的指令值。然後，將求出的指令值與用於掃描基板W的指令值相加，向基板載置台40供給。這樣，在藉由驅動基板載置台40來修正曝光的光EL的變動量的情況下，也可以不具備用於驅動投影光學系統30的光學元件的致動器34~36，因此能夠謀求裝置結構的簡化。另外，在本實施方式中，說明了向基板載置台40供給用於修正曝光的光EL的變動量的指令值的結構，但也可以是向原版載置台20供給的結構。另外，也可以藉由基板載置台40與原版載置台20的驅動相對地進行曝光的光EL的變動量的修正。而且，在設有用於驅動投影光學系統30的驅動機構的情況下，也可以藉由投影光學系統30的驅動來進行曝光的光EL的變動量的修正。
＜第3實施方式＞
說明本發明的第3實施方式。本實施方式基本上繼承了第1實施方式和/或第2實施方式，因此以下說明與這些實施方式不同的態樣。
在測量部50中，對於投光部51(光源51a)而言，測量光ML的出射方向、出射位置有時發生變動。這樣，若在投光部51中測量光ML的出射方向、出射位置發生變動(即，自目標出射方向/位置發生偏移)，則難以使測量光ML以所期望的入射角度和入射位置向投影光學系統30入射。其結果，根據測量光ML在受光元件52a上的變動量換算的曝光的光EL在基板上的變動量可能產生因測量部50本身引起的誤差。該誤差是在曝光的光EL中未產生的測量失誤分量。因此，若基於該誤差產生的受光元件52a的受光結果估計曝光的光EL在基板上的變動量，基於該曝光的光EL的變動量修正曝光的光EL向基板上的照射位置，則會產生對比度降低、像偏這樣的成像性能下降。
因此，本實施方式的測量部50具有用於檢測從投光部51(光源51a)出射的光束的出射角度和出射位置中的至少一者(在以下有時稱為“出射角度等”)的檢測部54。也就是說，檢測部54能夠構成為將向投影光學系統30入射的測量光ML的入射角度和入射位置中的至少一者(在以下有時稱為“入射角度等”)作為因測量部50引起的測量光ML的偏移位置變動量進行檢測。另外，在本實施方式的情況下，控制部60基於由檢測部54檢測到的偏移位置變動量修正測量光ML在受光元件52a上的變動量，能夠基於由此得到的值估計曝光的光EL在基板上的變動量。
圖4是表示第3實施方式的曝光裝置300的結構的概略圖。本實施方式的曝光裝置300與第1實施方式的曝光裝置100相比，不同點在於在測量部50設有檢測部54。除此之外的結構與第1實施方式的曝光裝置100同樣，因此省略說明。
檢測部54設於投影光學系統30的外部，例如能夠包括分束器54a(第2分支部)、受光元件54b(第2受光元件)、受光元件54c(第3受光元件)以及反射鏡54d。檢測部54的各構成部件(分束器54a、受光元件54b、54c、反射鏡54d)與投影光學系統30相對固定，較佳是安裝於投影光學系統30。另外，在本實施方式的測量部50的結構中，代替投光部51的反射鏡51b而設有分束器55(分支部)。
從投光部51的光源51a射出的光束利用分束器55分支為2束光束。由分束器55分支的2束光束中的一束光束作為測量光ML引導到投影光學系統30內，另一束光束作為用於檢測測量光ML的入射角度等的檢測光DL向檢測部54(分束器54a)引導。引導至檢測部54的檢測光DL由分束器54a分支為2束光束，一束光束(第1檢測光DL1)經由反射鏡54d向受光元件54b引導，另一束光束(第2檢測光DL2)向受光元件54c引導。在此，受光元件54b、54c例如為與受光部52的受光元件52a同樣的結構，能夠由4象限光電二極體構成。因而，在各個受光元件54b、54c中求出檢測光DL在受光面的變動量的方法與在受光部52的受光元件52a求出測量光ML在受光面53的變動量的方法(在第1實施方式中說明的內容)是同樣的。
由受光元件54b接受的第1檢測光DL1的光程長度與由受光元件54c接受的第2檢測光DL2的光程長度設定為已知且互不相同的長度。若像這樣使第1檢測光DL1和第2檢測光DL2的光程長度互不相同，則第1檢測光DL在受光元件54b的受光面的變動量與第2檢測光DL在受光元件54c的受光面的變動量互不相同。因此，控制部60能夠基於由受光元件54b得到的第1檢測光DL的變動量與由受光元件54d得到的第2檢測光DL的變動量之差檢測從投光部51(光源51a)出射的光束的出射角度等。另外，投光部51(光源51a)、分束器55以及投影光學系統30的位置關係是已知的，因此能夠基於該出射角度等求出測量光ML向投影光學系統30的入射角度等作為偏移位置變動量。
另一方面，通過了投影光學系統30的測量光ML由受光部52的受光元件52a(受光面53)接受。由受光元件52a得到的測量光ML的變動量能夠包括因投影光學系統30的各光學元件的振動引起的分量、因投影光學系統30內的環境波動引起的分量以及測量光ML向投影光學系統30的入射角度等的誤差等因測量部50本身引起的分量。在本實施方式的情況下，控制部60從測量光ML在受光元件52a上的變動量去除由檢測部54檢測出的偏移位置變動量，基於由此得到的值，估計曝光的光EL在基板上的變動量。這樣，基於去除因測量部50本身引起的偏移位置變動量而得到的值，估計曝光的光EL在基板上的變動量，從而能夠精度良好地進行曝光的光EL在基板上的照射位置的修正。
＜第4實施方式＞
說明本發明的第4實施方式。在本實施方式中，對將檢測偏移位置變動量的檢測部54設於測量部50的第3實施方式的變形例進行說明。本實施方式基本上繼承了第3實施方式，因此以下對與第3實施方式不同的點進行說明。
圖5是表示第4實施方式的曝光裝置400的結構的概略圖。本實施方式的曝光裝置400與第3實施方式的曝光裝置300相比，從測量部50(檢測部54)刪除了受光元件54c。即，本實施方式的檢測部54由受光元件54b(第2受光元件)構成。
從投光部51的光源51a射出的光束由分束器55分支為2束光束。由分束器55分支的2束光束中的一束光束作為測量光ML向投影光學系統30內引導，另一束光束作為用於檢測測量光ML的入射角度等的檢測光DL向受光元件54b引導。在此，本實施方式的測量部50被構成為由受光元件54b接受的檢測光DL的光程長度與由受光部52的受光元件52a接受的測量光ML的光程長度大致相同。例如，檢測光DL以與測量光ML的光程長度大致相同的方式，被多個反射鏡引繞而由受光元件54b接受。
具體而言，以測量光ML的光路與檢測光DL的光路大致相同的方式構成檢測部54。測量光ML的光程長度經由投影光學系統30的多個光學元件，因此將檢測光DL的光路在裝置內連結成一條直線是不實際的。因此，較佳是使用彎折鏡、回射器等光學元件，在有限的空間中獲得光程長度。另外，用於擴大這些光程長度的光學元件被相對地固定於投影光學系統30為佳，較佳是，安裝於投影光學系統30為佳。由此，能夠利用投影光學系統30單體對測量光偏移進行測量，因此能夠在組裝曝光裝置之前，用於作為投影光學系統單元單體的單元檢查等。
在這樣的結構中，在假設在投影光學系統30中不產生各光學元件的振動、環境波動的情況下，測量光ML在受光元件52a上的變動量與檢測光DL在受光元件54b上的變動量可能相同。也就是說，由受光元件52a得到的測量光ML的變動量與由受光元件54b得到的檢測光DL的變動量之差成為因投影光學系統30的各光學元件的振動、環境波動引起的分量。因而，控制部60從測量光ML在受光元件52a上的變動量去除檢測光DL在受光元件54上的變動量，能夠基於由此得到的值估計曝光的光EL在基板上的變動量。
在此，光程長度大致相同是指如下這樣的程度的範圍：即使發生測量光ML或者檢測光DL的變動(例如傾斜度變動)，由此產生的受光元件上的受光位置的變動量也能夠視為大致相同。這根據應用而不同，其範圍會根據作為目的的位置變動的測量精度(解析度)、光束自光源51a的射出角度等的變動量而變化。例如，在由光源51a及其固定系統引起的測量光ML的傾斜度變動為10μrad左右的情況且是想要將基於光程長度誤差的測量誤差設定為10nm以下的情況下，需要將該光程長度誤差抑制為1mm左右。在該情況下，大致相同的光程長度相當於其光程長度差為1mm以下。另一方面，在容許基於光程長度誤差的測量誤差大到1μm左右的情況下，該光程長度誤差也可以為100mm左右。在該情況下，對於大致相同的光程長度而言，其光程長度差也可以為100mm以下，即使是比之前的例子大的光程長度差，也能夠視為大致相同。
＜第5實施方式＞
說明本發明的第5實施方式。在本實施方式中，說明由在第1~第4實施方式中說明的曝光裝置進行的曝光處理。圖6是表示曝光處理的流程圖。圖6所示的流程圖的各工序能夠由控制部60控制。
在S1中，控制部60使用未圖示的基板輸送機構將基板W送入到基板載置台40上，使基板載置台40保持基板W。在S2中，控制部60進行全域對準處理。例如，控制部60使用對準觀察儀(未圖示)，對形成於基板W的多個照射區域中的採樣照射區域的對準標記的位置進行測量，藉由對該測量結果進行統計處理，從而得到多個照射區域的排列資訊。
在S3中，控制部60對多個照射區域的各照射區域依次進行掃描曝光，將原版M的圖案作為潛像圖案轉印到各照射區域(具體而言，其上的感光材料(抗蝕劑))。在S3中的各照射區域的掃描曝光中，如在上述第1~第4實施方式中說明的那樣，利用測量部50測量投影光學系統30的光學特性，基於該測量結果進行曝光的光EL向基板上的照射位置的修正。即，能夠在各照射區域的掃描曝光中，即時地進行基於測量部50的測量結果的曝光的光EL的照射位置的修正。
在S4中，控制部60使用未圖示的基板輸送機構，從基板載置台40搬出基板W。在S5中，控制部60判斷是否存在應進行掃描曝光的下一個基板。在存在下一個基板的情況下，返回S1，對該下一個基板進行掃描曝光。另一方面，在沒有下一個基板的情況下結束。
＜物品的製造方法的實施方式＞
本發明的實施方式的物品的製造方法例如適於製造半導體器件等微型器件、具有微細構造的元件等物品。本實施方式的物品的製造方法包括：使用上述曝光裝置將潛像圖案形成在塗布於基板的感光劑的工序(對基板進行曝光的工序)；以及對在該工序中形成了潛像圖案的基板進行顯影(加工)的工序。並且，該製造方法包括其它公知的工序(氧化、成膜、蒸鍍、摻雜、平坦化、蝕刻、抗蝕劑剝離、切割、鍵合、封裝等)。本實施方式的物品的製造方法與以往的方法相比，在物品的性能、品質、生產率、生產成本中的至少一個方面是有利的。
(其它實施例)
本發明也能夠藉由經由網路或者存儲介質將實現上述實施方式的1個以上的功能的程式向系統或者裝置供給、並由該系統或者裝置的電腦中的1個以上的處理器讀出並執行程式的處理來實現。另外，也能夠藉由實現1個以上的功能的電路(例如，ASIC)來實現。
其它實施例
本發明的實施例還可以藉由如下的方法來實現，即，藉由網路或者各種存儲介質將執行上述實施例的功能的軟體(程式)提供給系統或裝置，該系統或裝置的電腦或是中央處理單元(CPU)，微處理單元(MPU)讀出並執行程式的方法。
發明並不限於上述實施方式，能夠在不脫離發明的精神和範圍的前提下進行各種各樣的變更和變形。因而，為了公開發明的範圍，附上申請專利範圍。Hereinafter, embodiments will be described in detail with reference to the attached drawings. It should be noted that the following embodiments do not limit the technical solutions within the scope of the patent application. Although a plurality of features are described in the embodiment, all of the plurality of features are not necessarily required for the invention, and a plurality of features may be combined arbitrarily. In addition, in the accompanying drawings, the same or the same structure is denoted with the same reference numeral, and repeated description is omitted. <First Embodiment> The exposure apparatus 100 of the first embodiment of the present invention will be described. The exposure apparatus 100 is a photolithography apparatus for manufacturing semiconductor devices, liquid crystal displays, and the like. The exposure apparatus 100 of this embodiment is a projection exposure in which the pattern image of the original plate (mask, reticle) is projected onto the substrate by a stepping method or a scanning method, thereby exposing the substrate and transferring the pattern of the original plate to the substrate. Device. Hereinafter, as the exposure apparatus 100, an exposure apparatus of a scanning method that scans and exposes a substrate using slit light is exemplified. [Structure of Exposure Apparatus] FIG. 1 is a schematic diagram showing the structure of an exposure apparatus 100 according to the first embodiment. The exposure apparatus 100 of this embodiment may include an illuminating optical system 10, a movable original plate stage 20 that holds the original plate M, a projection optical system 30, a movable substrate stage 40 that holds the substrate W, a measurement unit 50, and a control unit 60 . The control unit 60 is constituted by a computer having, for example, a CPU, a memory, etc., and controls the exposure processing of the substrate W (each part of the exposure apparatus 100). The original plate M is a glass original plate formed by forming a fine pattern (for example, a circuit pattern) to be transferred onto the substrate W from a light-shielding material such as chromium. In addition, as the substrate W, a semiconductor wafer, a glass plate, or the like can be used. In order to obtain a desired illuminance distribution on the original plate, the illumination optical system 10 shapes the light from a light source (not shown) into, for example, an arc-shaped light that is long in the Y-axis direction, and uses the shaped light (slit light). ) Illuminate the original plate M with substantially uniform illuminance. A mercury lamp or the like can be used as the light source. The original plate M and the substrate W are held by the original plate stage 20 and the substrate stage 40, respectively, and are arranged at positions that are approximately optically conjugate via the projection optical system 30 (positions of the object surface and the image surface of the projection optical system 30). The projection optical system 30 has a predetermined projection magnification, and uses a plurality of mirrors to reflect the pattern image of the mask 1 and project it onto the substrate 2. In addition, the mask stage 20 and the substrate stage 40 are relatively synchronously scanned in a direction parallel to the object plane of the projection optical system 30 (for example, the X-axis direction) at a speed ratio corresponding to the projection magnification of the projection optical system 30. Thereby, scanning exposure of the substrate W can be performed, and the pattern formed on the original plate M can be transferred to the substrate W (specifically, the resist (photosensitive agent) on the substrate). For example, as shown in FIG. 1, the projection optical system 30 can be configured to include a trapezoidal mirror 31, a concave mirror 32, and a convex mirror 33. The pattern light EL (hereinafter sometimes referred to as “exposure light EL”) emitted from the illumination optical system 10 and passing through the original plate M is bent by the upper surface of the trapezoidal mirror 31 and enters the upper part of the reflective surface of the concave mirror 32. The exposure light EL reflected on the upper portion of the reflective surface of the concave mirror 32 is reflected on the reflective surface of the convex mirror 33 and enters the lower portion of the reflective surface of the concave mirror 32. The exposure light EL reflected on the lower part of the reflective surface of the concave mirror 32 is bent in the optical path by the lower surface of the trapezoidal mirror 31 and enters the substrate W. In the projection optical system 30 configured in this way, the reflective surface of the convex mirror 33 serves as a pupil. In addition, the projection optical system 30 does not generate magnification errors caused by the positional fluctuations of the original plate M and the substrate W in the optical axis direction (Z direction). Both are telecentric optical systems. In addition, the projection optical system 30 can be provided with an actuator for driving each optical element. Specifically, an actuator 34 for driving the trapezoidal mirror 31, an actuator 35 for driving the concave mirror 32, and an actuator 36 for driving the convex mirror 33 can be provided. Each of the actuators 34 to 36 can be used to reduce the fluctuation (vibration) of each optical element. Here, the actuator 35 is preferably arranged in at least three places for the concave mirror 32. As the actuator 35, for example, an actuator composed of a fixed part and a movable part in a non-contact manner, such as an electromagnetic actuator, can be used. In this case, deformation of the concave mirror 32 due to interference of the support part of the concave mirror 32 can be avoided. In addition, in this case, it is desirable to attach a coil as a heat source to the support portion side of the concave mirror 32 and attach a magnet as a non-heat source to the concave mirror 32. The electromagnetic actuator can be either an electromagnetic actuator using the attractive force of an electromagnet or a voice coil type linear motor. In the case of using a voice coil type linear motor, the force of components other than the driving direction becomes smaller, so it is more suitable. The same applies to the actuator 34 provided on the trapezoidal mirror 31 and the actuator 35 provided on the convex mirror 33, and it is preferable to use an electromagnetic actuator or to arrange the heat source away from the optical element. In addition, as the actuators 34 to 36, if a member other than the driving direction supported by the offset mechanism is used, a piezoelectric type or a screw feed mechanism can also be used. In such an exposure apparatus 100, it is generally possible to install a vibration damping device (not shown) that attenuates the disturbing vibration from the installation floor, but it is difficult to use the vibration damping device to eliminate the disturbing vibration. Therefore, in the scanning exposure of the substrate W, there are cases in which disturbance vibration is transmitted to each part of the exposure apparatus 100 (especially the projection optical system 30). In addition, in the scanning exposure of the substrate W, the original plate mounting table 20 and the substrate mounting table 40 move, and therefore the vibration generated by the movement may also be transmitted to the projection optical system 30. In these cases, each optical element (for example, the trapezoidal mirror 31, the concave mirror 32, and the convex mirror 33) included in the projection optical system 30 vibrates, and the position of the exposure light EL changes (vibration, image deviation). As a result, it may be difficult to accurately project the pattern image of the original plate M onto the substrate, that is, it may be difficult to accurately transfer the pattern image of the original plate M onto the substrate. Therefore, the exposure apparatus 100 of the present embodiment includes the measurement unit 50 for measuring the optical characteristics of the projection optical system 30, and corrects the irradiation position of the exposed light EL on the substrate based on the measurement result of the measurement unit 50. The measurement unit 50 projects the measurement light ML as parallel light (collimated light) into the projection optical system, and measures the projection optical system 30 based on the measurement light ML of the optical element in the projection optical system through which the exposed light EL passes. The optical characteristics of the projection optical system 30, that is, the internal state of the projection optical system 30. Specifically, the measurement unit 50 has a light projecting unit 51 that projects measurement light ML (light beam) into the projection optical system 30 and a light receiving unit 52 that receives the measurement light ML emitted by the projection optical system 30. In the projection optical system 30, the measurement light ML is the same as the exposure light EL, according to the upper surface of the trapezoidal mirror 31, the upper part of the reflective surface of the concave mirror 32, the lower part of the reflective surface of the convex mirror 33, the concave mirror 32, and the bottom of the trapezoidal mirror 31. The surface is sequentially reflected and emitted from the projection optical system 30. The light projecting unit 51 can include, for example, a light source 51a and a reflecting mirror 51b. The light source 51a has light-emitting elements such as a gas laser, a semiconductor laser, an LED, and a collimator lens, and emits the measurement light ML as parallel light (collimated light). The mirror 51b bends the optical path of the measurement light ML emitted from the light source 51a, and guides the measurement light ML into the projection optical system 30. The light projecting unit 51 (light source 51 a, mirror 51 b) is mounted on the projection optical system 30 between the original plate mounting table 20 (original plate M) and the projection optical system 30. In addition, the light projection unit 51 is configured to make the measurement light ML parallel to the optical axis of the projection optical system 30 by using a mirror 51 b arranged between the original plate M and the projection optical system 30. By arranging the mirror 51b on the lower side of the original plate M in this way, the measurement light ML can always be incident on the projection optical system 30. The light receiving unit 52 can include, for example, a light receiving element 52a and a reflecting mirror 52b. The mirror 52b bends the optical path of the measurement light ML passing through the projection optical system 30 and emitted from the projection optical system 30 in front of the substrate W, and guides the measurement light ML to the light receiving element 52a. The light receiving element 52a receives the measurement light ML, and outputs a signal value corresponding to the light receiving position of the measurement light ML. In the case of this embodiment, the light-receiving element 52a has a light-receiving surface 53 that receives the measurement light ML, and outputs a signal value corresponding to the light-receiving position of the measurement light ML on the light-receiving surface 53. The specific structure of the light receiving element 52a will be described later. The light receiving unit 52 (the light receiving element 52 a and the mirror 52 b) is mounted on the projection optical system 30 between the substrate mounting table 40 (substrate W) and the projection optical system 30. In the case of this embodiment, the projection optical system 30 is a telecentric optical system on both sides, and the measurement light ML is incident parallel to the optical axis of the projection optical system 30. Therefore, on the substrate W side of the projection optical system 30, the measurement light ML is also The optical axis is emitted in parallel. In addition, since parallel light is used as the measurement light ML, there is no need to consider the imaging position of the projection optical system 30 regarding the position where the light receiving element 52a (light receiving surface 53) is arranged. Therefore, the light-receiving element 52a (light-receiving surface 53) of this embodiment may be arranged at a position different from the imaging position of the projection optical system 30. Here, when a semiconductor laser or LED is used as the light source 51a of the light projection unit 51, the measurement light ML can be flashed quickly, and therefore the measurement light ML having a specific frequency can be emitted. In this case, by synchronizing the output frequency of the signal from the light receiving element 52a of the light receiving section 52 with the frequency of the measurement light ML emitted from the light source 51a, the noise component can be reduced. That is, the signal value of the light receiving element 52a focusing on the specific frequency component can be obtained. The measuring unit 50 configured as described above can be provided in plural with respect to the exposed light EL. 2 is a view of the projection optical system 30 viewed from above (on the side of the original plate mounting table 20), and illustrates the cross-section of the exposed light EL (illumination area 11) and the light projection unit 51 (light source 51a, reflection light source 51a) of the measurement unit 50 Mirror 51b). The plurality of measurement units 50 can be arranged at a plurality of locations around the exposed light EL so that the plurality of measurement lights ML are projected into the projection optical system 30, respectively. In the example shown in FIG. 2, four measuring parts 50 are provided. The four measuring parts 50 are arranged around the exposed light EL (illumination area 11) so as to cross the optical axis (Z axis of the exposed light EL). Direction) and a straight line parallel to the scanning direction (X direction) is line symmetry of the axis. By providing a plurality of measurement units 50 in this way, not only the positional change (optical axis shift) of the measurement light ML in the projection optical system 30 can be measured, but also the magnification component of the projection optical system 30 can be measured. It should be noted that the position change of the measurement light ML means that the optical axis of the measurement light ML changes from the reference position to the translation direction (XY direction) and the rotation direction (rotation direction around the Z axis) due to the projection optical system 30 (Offset). In addition, the reference position can be the optical axis position of the measurement light ML to be emitted from the projection optical system 30 according to the incident position of the projection optical system 30. Next, a method of measuring the optical characteristics of the projection optical system 30 using the light receiving element 52a of the light receiving unit 52 will be described. For the light receiving element 52a, for example, a light intensity sensor (photoelectric conversion sensor) such as a photodiode can be used. In the case of the present embodiment, the light receiving element 52 a can include a plurality of photodiodes configured to be able to detect light intensity in each of the plurality of partial regions of the light receiving surface 53. In the following, an example in which four photodiodes (also referred to as 4-quadrant photodiodes) are used for the light receiving element 52a will be described. FIG. 3 is a diagram showing the light-receiving surface 53 of the light-receiving element 52a of this embodiment. In the case of this embodiment, the light-receiving surface 53 is a YZ surface as shown in FIG. 1. However, in FIG. 3, for easy understanding of the description, the light-receiving surface 53 is set as an XY surface instead of using the mirror 52b of the light-receiving portion 52. The situation is explained. In addition, in the example shown in FIG. 3, the light receiving element 52a is composed of a 4-quadrant photodiode, and the light receiving surface 53 has four partial regions 53a to 53d capable of independently detecting light intensity. That is, the four-quadrant photodiode as the light receiving element 52a is configured to independently output signal values (for example, current values) corresponding to the amounts of light incident on the partial regions 53a to 53d. In addition, the signal value (current value) independently output from the 4-quadrant photodiode can be connected to a current-to-voltage converter and converted into a voltage value. For example, as shown in FIG. 3, consider a case where the measurement light ML is incident on the center position of the light receiving surface 53 (the center position of the 4-quadrant photodiode). In this case, four voltage values A, B, C, and D are respectively obtained from the four-quadrant photodiode. The voltage values A, B, C, and D depend on the light quantity of the measurement light EL, the sensitivity of the photodiode, the gain of the current-voltage converter, and the like. In addition, these voltage values change in accordance with the change in the position of the measurement light EL, and the amount of change depends on the diameter and shape (light quantity distribution) of the measurement light EL. For example, if the incident position (light-receiving position) of the measuring light EL changes to the right (+X direction) from the state of FIG. 53a, 53d received light reduction. In other words, the voltage values B and C increase, and the voltage values A and D decrease. On the other hand, if the incident position (light-receiving position) of the measuring light EL moves upward (+Y direction) from the state of FIG. The amount of light received in the areas 53a to 53b is reduced. In other words, the voltage values C and D increase, and the voltage values A and B decrease. Therefore, the control unit 60 can obtain the light-receiving position shift of the measuring light ML when the center position of the light-receiving surface 53 is used as a reference based on the voltage values A to D obtained from the 4-quadrant photodiode. The light-receiving position shift of the measuring light ML on the light-receiving surface 53 is proportional to the optical axis shift (X, Y) of the measuring light ML in the projection optical system 30, and can be calculated by the following equations (1) to (2). It should be noted that the above-mentioned calculation can be performed by the control unit 60 in this embodiment, but when a processing unit such as a CPU is provided in the measurement unit 50, it can also be performed by this processing unit. The coefficient kx of the formula (1) is a conversion coefficient for converting the light receiving position shift (X direction) of the measuring light ML on the light receiving surface 53 into the optical axis shift (X direction) of the measuring light ML in the projection optical system 30 (Proportion factor). Similarly, the coefficient ky of equation (2) is used to convert the light receiving position shift (Y direction) of the measuring light ML on the light receiving surface 53 into the optical axis shift (Y direction) of the measuring light ML in the projection optical system 30 The transformation coefficient (scale factor). The coefficient kx and the coefficient ky can be obtained by, for example, prior experiments and simulations. In one example, by changing the incident position of the measuring light ML to the projection optical system 30, the optical axis of the measuring light ML in the projection optical system 30 is shifted, and the light receiving position of the measuring light ML on the light receiving surface 53 is measured successively. Therefore, the coefficient kx and the coefficient ky can be obtained. In addition, when the diameter of the measuring light ML is larger than the light-receiving surface 53 of the 4-quadrant photodiode, or is too small to ignore the width of the joint area of the 4-quadrant photodiode (the area where the light intensity cannot be detected) In the case of, the voltage values A to D can also be normalized. Specifically, when the total amount of light received in the plurality of partial regions 53a to 53d changes due to the deviation of the light receiving position of the measuring light ML on the light receiving surface 53, as shown in the following equations (3) to (4) It shows that by normalizing the total amount of received light, the linear improvement can be mainly achieved. It should be noted that the coefficient kx' and coefficient ky' of equations (3) to (4) are used to convert the deviation of the light receiving position of the measuring light ML on the light receiving surface 53 into the light of the measuring light ML in the projection optical system 30. The transformation factor (scale factor) of the axis offset. Here, the measurement light ML has passed through a plurality of optical elements through which the exposed light EL in the projection optical system 30 passes. Therefore, the optical axis shift of the measuring light ML in the projection optical system 30 obtained by the calculation of the light receiving position shift of the measuring light ML on the light receiving surface 53 can be compared with the positional shift (image shift) of the exposed light EL on the substrate. correspond. That is, the control unit 60 can estimate the position change of the exposed light EL in the projection optical system 30 based on the light receiving position of the measurement light ML on the light receiving element 52a (light receiving surface 53) by performing the above calculation. Then, it is possible to correct the irradiation position of the exposed light EL on the substrate based on the estimated position change of the exposed light EL. In the case of the present embodiment, it is possible to perform correction of the irradiation position of the exposed light EL on the substrate in parallel with the scanning exposure of the substrate W. In this way, in the exposure apparatus 100 of this embodiment, by using the measuring light ML which is a parallel light, a plurality of photodiodes (for example, a 4-quadrant photodiode) can be applied as the light receiving element 52a. That is, in the structure of the present embodiment, as described in Patent Document 1, an image sensor composed of a light detecting element such as a CMOS sensor and a light receiving optical system is used to detect the projection image of the mark. Compared with the structure, the optical characteristics of the projection optical system 30 can be measured with a simple structure. In addition, in the configuration of the present embodiment, since the projection image of the mark is not used for the measurement of the optical characteristics of the projection optical system 30, the light receiving surface of the light receiving element 52a can be arbitrarily arranged regardless of the imaging position of the projection optical system 30 53. That is, the light receiving surface 53 can be arranged at a position different from the imaging position of the projection optical system 30. Therefore, it is advantageous in terms of device cost and device design freedom. In addition, the photodiode is used in the configuration of the present embodiment, and the calculation scale is smaller than the conventional configuration that calculates the position of the projected image of the mark. Therefore, the measurement period of the optical characteristics of the projection optical system 30 can be shortened. That is, in the conventional configuration, the optical characteristics of the projection optical system 30 are measured discretely, while in the configuration of this embodiment, the optical characteristics of the projection optical system 30 can be continuously measured. [Correction of the irradiation position of the exposure light] The change in the optical characteristics of the projection optical system 30, that is, the position change of the exposed light EL in the projection optical system 30, may be caused by, for example, the vibration of the optical element of the projection optical system 30 or the projection optical system. Caused by environmental fluctuations (air fluctuations) within 30. When the positional variation of the exposure light EL is caused by the optical elements (trapezoidal mirror 31, concave mirror 32, convex mirror 33) of the projection optical system 30, the control unit 60 drives the optical elements by the actuators 34 to 36. Correction of the irradiation position of the exposed light EL on the substrate. On the other hand, when the position of the exposed light EL fluctuates due to environmental fluctuations in the projection optical system 30, the control unit 60 adjusts the temperature and/or pressure in the projection optical system 30 so that the exposed light EL is Correction of the irradiation position on the substrate. In the case of this embodiment, as shown in FIG. 1, an adjustment unit 71 for adjusting the temperature and/or pressure in the projection optical system 30 can be provided. An example of a method of correcting the irradiation position of the light EL on the substrate based on the measurement result of the measurement unit 50 will be described. As described above, the positional variation of the exposed light EL in the projection optical system 30 may be caused by the vibration of the optical elements of the projection optical system 30 and/or environmental fluctuations in the projection optical system 30. For example, in a plurality of optical elements (e.g., trapezoidal mirror 31, concave mirror 32, convex mirror 33) constituting the projection optical system 30, the weights are different from each other, and therefore the natural frequency (vibration frequency) is also different from each other. Therefore, by investigating the frequency component of the fluctuation (vibration) of the light receiving position of the measuring light ML on the light receiving element 52a, it is possible to identify the optical element that affects the fluctuation of the light receiving position of the measuring light ML, that is, the positional change of the exposed light EL. In the case of the present embodiment, the control unit 60 uses fast Fourier transform or the like to perform frequency analysis (ie, decomposition into a plurality of frequency components) of the variation (vibration) of the light receiving position of the measurement light ML in the light receiving element 52a. Then, when a frequency component corresponding to the natural frequency of the concave mirror 32 is obtained as a result of the frequency analysis, the control unit 60 issues a command to the actuator 35 to attenuate (dampen) the vibration of the concave mirror 32. As an example, the control unit 60 performs coordinate conversion, gain adjustment, filtering, etc., on the direction and magnitude of the light-receiving position shift of the measurement light ML when the center position of the light-receiving element 52a (light-receiving surface 53) is used as a reference, to obtain the result The command value of the actuator 35. By supplying the command value thus obtained to the actuator 35, the vibration of the concave mirror 32 can be reduced. Similarly, when the frequency component corresponding to the natural vibration frequency of the trapezoidal mirror 31 and/or the convex mirror 33 is obtained, the control unit 60 provides command values to the actuators 34 and 36 to make the trapezoidal mirror 31 and/or the convex mirror 33 The vibration attenuation. In addition, when a frequency component lower than the natural frequency of each optical element of the projection optical system 30 is obtained as a result of the frequency analysis, the refractive index due to environmental fluctuations (temperature, pressure) in the projection optical system 30 is considered. The impact of changes. In this case, the control unit 60 adjusts the temperature and/or pressure in the projection optical system 30 by the adjustment unit 71, so that the change in the receiving position of the measuring light ML, that is, the position change of the exposed light EL can be reduced. For example, the control unit 60 provides the adjustment unit 71 with a command value for changing the control parameter of the environment in the projection optical system 30, so that the position variation of the exposure light EL can be reduced, and the exposure position of the exposure light EL on the substrate can be reduced. Fix. As shown in FIG. 2, in a configuration in which a plurality of measurement units 50 are provided, it is possible to partially detect the positional change of the exposed light EL. In this case, it is possible to selectively correct the irradiation position of the exposed light EL in a portion where the position of the exposed light EL changes. In addition, in the structure shown in FIG. 2, not only can the translation direction and rotation direction be measured, but also the magnification component of the projection optical system can be measured. Therefore, each actuator 34 to 36 and the adjustment unit 71 can be controlled to correct the projection optical system. A magnification component of 30. Here, the control loop that reduces the vibration of each optical element of the projection optical system 30 based on the detection result in the light receiving element 52a as described above is the position feedback. Therefore, in order to further improve the controllability and stability of the vibration of each optical element, acceleration feedback may be further applied. For example, an acceleration sensor may be provided in each optical element of the projection optical system 30, and an acceleration feedback that reduces the vibration of the optical element based on the acceleration of the optical element detected by the acceleration sensor may be further applied. In the example shown in FIG. 1, acceleration sensors 37 a to 37 c are respectively provided for a plurality of optical elements (trapezoidal mirror 31, concave mirror 32, and convex mirror 33) in the projection optical system 30. [Estimation of Variation of Exposure Light] Next, the installation position of the light receiving element 52a in the measurement section 50 will be described. In the case where the optical path length of the exposed light EL from the projection optical system 30 to the substrate W is approximately the same as the optical path length of the measurement light ML from the projection optical system 30 to the light receiving element 52a (light receiving surface 53), it can also be considered The fluctuation (vibration) of the measuring light ML is substantially the same as the fluctuation (vibration) of the exposure light EL. In this case, the control unit 60 can consider that the fluctuation (vibration) of the exposure light EL is substantially the same as the fluctuation (vibration) of the measurement light ML obtained by the light receiving element 52a, and can control the actuators 34-36. However, various components for exposure are arranged in the area between the projection optical system 30 and the substrate W (substrate mounting table 40), and it may be difficult to arrange the light receiving element 52a in a desired place. When it is impossible to arrange the optical path length of the projection optical system 30 to be approximately the same for the exposed light EL and the measuring light ML, it is preferable to use the variation amount (light receiving position deviation) of the measuring light ML obtained by the light receiving element 52a. The amount of shift) estimates the amount of variation of the exposure light EL (the amount of shift of the irradiation position on the substrate). For example, suppose that the exposure light EL and the measurement light ML are bent by the same angle due to vibration of each optical element of the projection optical system 30. In this case, the difference between the optical path length until the curved measuring light ML reaches the light receiving element 52a and the optical path length until the curved exposure light reaches the substrate W may cause the measuring light ML to fall on the light receiving element 52a (light-receiving surface 53). The amount of variation in (above) is different from the amount of variation of the exposed light EL on the substrate. However, these optical path lengths can be known, so it is possible to use these optical path length ratios as conversion coefficients to convert the amount of variation of the measurement light ML on the light receiving element 52a into the amount of variation of the exposed light EL on the substrate. Here, the plurality of optical elements (trapezoidal mirror 31, concave mirror 32, convex mirror 33) in the projection optical system 30 are generally arranged at locations where the optical path lengths of the exposure light EL are different from each other. That is, the optical path length of the exposed light EL up to the substrate W can be different among the plurality of optical elements. Therefore, if a conversion factor that is commonly set in a plurality of optical elements is used to simply convert the amount of variation of the measurement light ML on the light receiving element 52a into the amount of variation of the exposure light EL on the substrate, the actual exposure light The amount of variation of EL on the substrate may cause errors. Therefore, it is preferable to set a conversion factor for each optical element. In the case of this embodiment, for each optical element, the optical path amount to the light receiving element 52a and the optical path length to the substrate W are known. Therefore, based on these optical path length ratios, each optical element (per Each natural frequency) to set the conversion factor. The control unit 60 uses fast Fourier transform or the like to convert the time-axis data of the variation of the measurement light ML obtained by the light receiving element 52a into frequency-axis data, performs frequency analysis, and determines the cause based on the frequency component obtained from the analysis result Optical element that measures the vibration of light ML. As described above, the plurality of optical elements in the projection optical system 30 have different natural vibration frequencies (vibration frequencies). Therefore, it is possible to determine which optical element vibration caused the measurement light ML based on the frequency components obtained as a result of frequency analysis. vibration. Therefore, the control unit 60 can select a conversion coefficient set in association with the identified optical element, and convert the amount of variation of the measurement light ML on the light receiving element 52a into the amount of variation of the exposed light EL on the substrate. As a result, it is possible to reduce the error that occurs in the amount of variation of the actual exposure light EL on the substrate. In addition, in each optical element of the projection optical system 30, there may be cases where the exposed light EL and the measuring light ML are reflected or transmitted in different places, or in order not to lighten the resist on the substrate, the light may be exposed to light. The EL and the measuring light ML have different wavelengths. In this case, the degree of influence of the vibration of each optical element may be different for the exposure light EL and the measurement light ML. Therefore, the amount of variation of the measurement light ML on the light receiving element 52a is converted into the exposure light EL on the substrate. Sometimes an error occurs when the amount of variation is. Therefore, the difference in the degree of influence of the vibration of each optical element of the exposure light EL and the measurement light ML is obtained through experiments, simulations, etc. (hereinafter sometimes referred to as "influence difference"), and the conversion factor is corrected to reduce the difference. . For example, using a pre-set conversion factor, the amount of variation of the measuring light ML on the light receiving element 52a is converted into the amount of variation of the exposure light EL on the substrate, and based on the obtained variation of the exposure light EL, the exposure is corrected. The light EL performs scanning exposure of the substrate W at the irradiation position on the substrate. When the pattern actually formed on the substrate by the scanning exposure produces errors such as image deviation and uneven exposure (for example, the overlap error with the base pattern), the error can be equivalent to the degree of influence of the exposure light EL and the measurement light ML Difference. Therefore, the conversion factor can be corrected to reduce the error. As described above, the amount of variation of the measuring light ML on the light receiving element 52a may be caused by environmental fluctuations (air fluctuations) in the projection optical system 30. The measuring light ML and the exposed light EL pass through the same space in the projection optical system 30, and therefore the measuring light ML is affected by environmental fluctuations that are substantially the same as the exposed light EL. Therefore, it is possible to estimate the amount of variation of the exposed light EL on the substrate due to environmental fluctuations in the projection optical system 30 based on the amount of variation of the measurement light ML on the light receiving element 52a. For example, in the result of frequency analysis of the variation of the light ML on the light receiving element 52a, at least a part of the frequency other than the natural frequency of the optical element of the projection optical system 30 can be regarded as being caused by the environment in the projection optical system 30. The amount of influence caused by fluctuations. The control unit 60 can adjust the temperature and/or pressure in the projection optical system 30 by using the adjustment unit 71 to correct the fluctuation amount of the exposure light EL caused by the environmental fluctuation, or it can use the actuators 34 to 36 The optical elements of the projection optical system 30 are driven to perform correction. It should be noted that the measurement unit 50 of the present embodiment can also be used as a sensor that monitors the degree of influence of environmental fluctuations in the projection optical system 30 during scanning exposure on the exposure light EL. Therefore, it can also be effectively used to develop hardware and device driver software for reducing environmental fluctuations. [Method for improving measurement accuracy] In order to improve the measurement accuracy of the variation of the measurement light ML in the measurement section 50, the irradiation position of the exposure light EL on the substrate is corrected with higher accuracy, and the measurement light ML is increased in the light receiving element 52a. The detection resolution in is better. Hereinafter, several methods for improving the detection resolution will be described. The first method is to reduce noise as much as possible. The signal value output from the light-receiving element 52a includes not only the original signal value based on the measurement light ML, but also the noise component caused by interference light other than the measurement light ML, generated by a current-voltage converter, etc. The electrical noise component of the Therefore, if these noise components are reduced as much as possible, the S/N ratio can be increased, and the detection resolution can be improved. As a method of reducing interference light, there is a method of shielding the periphery of the light-receiving element 52a or using a wavelength filter to block interference light other than the measurement light ML. In addition, as a method of reducing the electrical noise component, there is a method of making the current-to-voltage converter used as low as possible of noise, or shielding the periphery of the light receiving element 52a with respect to the surrounding electromagnetic field. In addition, the noise and gain of the current-to-voltage converter are related to each other, so it is better to consider both. The second method is to reduce the diameter of the measurement light ML incident on the light receiving element 52a as much as possible. The smaller the diameter of the measuring light ML, the sharper the light intensity distribution becomes. Therefore, even the same variation of the measuring light ML, the signal obtained from the 4-quadrant photodiode (each partial area 53a~53d) can be used. The value changes to a large extent. This means that the sensitivity is improved, and since the signal side of the S/N ratio is improved, smaller position changes can be detected. The third method is to adjust the light intensity (light amount) of the measurement light ML so that the voltage values A to D output from the light receiving element 52a (4-quadrant photodiode) are close to the maximum output of the current-to-voltage converter. This also has the effect of increasing the voltage fluctuation (signal) of the light receiving element 52a caused by the positional change of the measurement light ML, and therefore the sensitivity of the light receiving element 52a can be improved. For example, by setting the light intensity (light intensity) of the measurement light ML output from the light source 51a to be higher than the required light intensity, and changing the light transmittance of the ND filter arranged between the light source 51a and the light receiving element 52a, The light intensity of the measurement light ML can be adjusted. In the fourth method, there is a method capable of measuring small voltages by using a high-resolution measurement system for measurement. Alternatively, by using an operational amplifier to amplify the signals of (AC) and (BD) in the above equations (1) to (4), it is possible to measure the voltage values A, B, C, and D output from the light receiving element 52a. The small voltage component of, can also seek to improve the resolution. However, generally speaking, the output of the operational amplifier is limited, so it is better to set the absolute values of the differential components (AC) and (BD) as small as possible and the average voltages of the respective voltage values A, B, C, and D to be the same. For example, in the case of using a differential amplifier with a maximum output of 10 [V], when the average value of the voltage value A is 8 [V] and the average value of the voltage value C is 7 [V], the differential amplifier The maximum magnification can only be 10 times. On the other hand, when the average value of the voltage value A is 8.0 [V] and the average value of the voltage value C is 7.9 [V], the magnification of the operational amplifier can be made up to 100 times, so it is possible to reduce the The voltage component is also amplified for detection. In order to be able to adjust the average voltage levels of the respective voltage values A, B, C, and D in the same manner, it is preferable to make the light intensity distribution of the measurement light ML symmetrical with respect to the optical axis. In addition, it is preferable to include a mechanism for adjusting the relative position of the measuring light ML and the light receiving element 52a. In the light receiving element 52a, the position of the light receiving element 52a with respect to the projection optical system 30 may change due to thermal deformation of the fixing portion or the like. Thus, in the plane direction (two orthogonal directions) orthogonal to the optical axis of the received measurement light ML, the exposure apparatus 100 is provided for adjusting the position and/or posture of the light receiving element 52a relative to the projection optical system 30 The adjustment mechanism is better. In addition, in the measurement unit 50, the emission direction and the emission position of the measurement light ML for the light source 51a of the light projection unit 51 may fluctuate. In addition, similarly to the light receiving element 52a, the light source 51a may also fluctuate in the emission direction and the emission position of the measurement light ML due to thermal deformation of the fixed portion thereof. In this way, if the emission direction and the emission position of the measurement light ML in the light source 51a fluctuate, it may be difficult to cause the measurement light ML to enter the projection optical system 30 at a desired incident angle and incident position. As a result, the amount of variation of the exposure light EL on the substrate converted from the amount of variation of the measurement light ML on the light receiving element 52a may cause an error due to the measurement unit 50 itself. Therefore, it is preferable to provide an adjustment mechanism in the exposure apparatus 100: the adjustment mechanism is used to adjust the position and/or posture of the light source 51a relative to the projection optical system 30 to change the position and the position of the measurement light ML emitted from the light source 51a / Or slope. It should be noted that in the process of adjusting the position and posture of the light source 51a and/or the light receiving element 52a, the amount of variation of the measurement light ML cannot be measured. Therefore, it is preferable not to adjust the position and posture of the light source 51a and/or the light-receiving element 52a during the scanning exposure of the substrate W, but, for example, in the replacement process of the original plate M and the substrate W, the original plate M and the substrate W Alignment processing is performed during processing other than scanning exposure. Here, in the present embodiment, the projection optical system 30 has been described as a reflective optical system, but it may also be a refractive optical system or a catadioptric optical system. In addition, the shape of the illumination area 11 (the cross-section of the exposed light EL) shown in FIG. 2 may be different depending on the optical system to be applied, but by disposing a mirror 51b on the periphery (outer circumference) of the illumination area 11. Arranging the light source 51a in the vicinity of the illumination area 11 has the same effect. In addition, in the present embodiment, a 4-quadrant photodiode is used as the light receiving element 52a, but it is also possible to use a plurality of photodiodes that are not a quadrant (division) type, and perform optical division using a prism or a beam splitter. In addition, in the present embodiment, an example in which a plurality of measurement units 50 (light-receiving elements 52a) are arranged has been described, but it is also possible to arrange only one measurement unit 50 (light-receiving element 52a) to measure only the variation of the measurement light ML in the translation direction. quantity. <Second Embodiment> The second embodiment of the present invention will be described. This embodiment basically inherits the first embodiment, and therefore the aspects different from the first embodiment will be described below. In the first embodiment, the optical elements of the projection optical system 30 are driven by the actuators 34 to 36 and/or the environment (temperature, pressure) in the projection optical system 30 is adjusted by the adjustment unit 71. Correction of the irradiation position of the exposed light EL on the substrate. In this embodiment, an example of correcting the irradiation position of the exposure light EL on the substrate by changing the relative position of the original plate M and the substrate W will be described. In the case of the present embodiment, the control unit 60 estimates the amount of variation of the exposed light EL on the substrate based on the amount of variation of the measurement light ML on the light receiving element 52a. Specifically, the amount of variation of the measurement light ML on the light receiving element 52a is converted into the amount of variation of the exposed light EL on the substrate using a conversion coefficient set in advance. Then, the control unit 60 drives the substrate mounting table 40 and controls (adjusts) the position of the substrate W to correct the estimated fluctuation amount of the light EL for exposure. For example, by averaging the signal value output from the light-receiving element 52a, or extracting the rotation component to perform a moving average on the illuminated area 11, coordinate conversion, gain adjustment, and filtering are performed at the same time to obtain the light EL value for correcting the exposure. The command value of the variation. Then, the obtained command value is added to the command value for scanning the substrate W and supplied to the substrate mounting table 40. In this way, in the case of correcting the fluctuation amount of the exposure light EL by driving the substrate stage 40, the actuators 34 to 36 for driving the optical elements of the projection optical system 30 may not be provided, so that the device structure can be achieved. Simplification. In addition, in the present embodiment, the configuration of supplying the command value for correcting the fluctuation amount of the exposure light EL to the substrate stage 40 has been described, but the configuration of supplying the original plate stage 20 may also be used. In addition, the fluctuation amount of the exposure light EL may be corrected by the driving of the substrate mounting table 40 and the original plate mounting table 20 opposite to each other. Furthermore, in the case where a driving mechanism for driving the projection optical system 30 is provided, it is also possible to correct the fluctuation amount of the exposure light EL by driving the projection optical system 30. <Third Embodiment> The third embodiment of the present invention will be described. This embodiment basically inherits the first embodiment and/or the second embodiment, so the following describes aspects different from these embodiments. In the measurement unit 50, the emission direction and the emission position of the measurement light ML may fluctuate with respect to the light projecting unit 51 (light source 51a). In this way, if the emission direction and the emission position of the measurement light ML in the light projecting unit 51 are changed (that is, the emission direction/position from the target is shifted), it is difficult to make the measurement light ML to the desired incident angle and incident position. The projection optical system 30 is incident. As a result, the amount of variation of the exposure light EL on the substrate converted from the amount of variation of the measurement light ML on the light receiving element 52a may cause an error due to the measurement unit 50 itself. This error is a measurement error component that is not generated in the exposed light EL. Therefore, if the amount of variation of the exposed light EL on the substrate is estimated based on the result of light reception by the light receiving element 52a caused by this error, and the irradiation position of the exposed light EL on the substrate is corrected based on the variation of the exposed light EL, it will be generated Contrast decreases, and imaging performance such as shifting decreases. Therefore, the measurement unit 50 of the present embodiment has a device for detecting at least one of the emission angle and the emission position of the light beam emitted from the light projecting unit 51 (light source 51a) (hereinafter sometimes referred to as "emission angle etc.") Detection section 54. That is, the detection unit 54 can be configured to use at least one of the incident angle and the incident position of the measurement light ML incident on the projection optical system 30 (hereinafter sometimes referred to as "incident angle, etc.") as the factor measurement unit 50 The amount of displacement caused by the measurement light ML is detected. In addition, in the case of the present embodiment, the control unit 60 corrects the amount of variation of the measuring light ML on the light receiving element 52a based on the amount of shift position detected by the detection unit 54 and can estimate the exposure light based on the value obtained thereby. The amount of variation of EL on the substrate. FIG. 4 is a schematic diagram showing the structure of an exposure apparatus 300 according to a third embodiment. The exposure apparatus 300 of the present embodiment is different from the exposure apparatus 100 of the first embodiment in that a detection section 54 is provided in the measurement section 50. The structure other than that is the same as that of the exposure apparatus 100 of the first embodiment, so the description is omitted. The detection unit 54 is provided outside the projection optical system 30, and can include, for example, a beam splitter 54a (second branch portion), a light receiving element 54b (second light receiving element), a light receiving element 54c (third light receiving element), and a mirror 54d. The components (beam splitter 54a, light receiving elements 54b and 54c, and mirror 54d) of the detection unit 54 are relatively fixed to the projection optical system 30, and are preferably installed in the projection optical system 30. In addition, in the configuration of the measurement section 50 of the present embodiment, a beam splitter 55 (branch section) is provided in place of the reflecting mirror 51b of the light projection section 51. The light beam emitted from the light source 51 a of the light projection unit 51 is branched into two light beams by the beam splitter 55. One of the two light beams branched by the beam splitter 55 is guided into the projection optical system 30 as the measuring light ML, and the other light beam is directed to the detection unit 54 as the detection light DL for detecting the incident angle of the measuring light ML, etc. (Beam splitter 54a) guide. The detection light DL guided to the detection unit 54 is branched into two light beams by the beam splitter 54a. One light beam (first detection light DL1) is guided to the light receiving element 54b via the mirror 54d, and the other light beam (second detection light DL2) ) Guide to the light receiving element 54c. Here, the light-receiving elements 54b and 54c have, for example, the same structure as the light-receiving element 52a of the light-receiving section 52, and can be composed of a 4-quadrant photodiode. Therefore, the method of obtaining the variation of the detection light DL on the light-receiving surface in each of the light-receiving elements 54b and 54c is the same as the method of obtaining the variation of the measurement light ML on the light-receiving surface 53 in the light-receiving element 52a of the light-receiving section 52 (in the first The content described in the embodiment) is the same. The optical path length of the first detection light DL1 received by the light receiving element 54b and the optical path length of the second detection light DL2 received by the light receiving element 54c are set to be known and different lengths. If the optical path lengths of the first detection light DL1 and the second detection light DL2 are different from each other in this way, the amount of variation of the first detection light DL on the light-receiving surface of the light-receiving element 54b and the second detection light DL on the light-receiving element 54c The amount of variation of the light-receiving surface is different from each other. Therefore, the control unit 60 can detect light emitted from the light projecting unit 51 (light source 51a) based on the difference between the amount of variation of the first detection light DL obtained by the light receiving element 54b and the amount of variation of the second detection light DL obtained by the light receiving element 54d. The exit angle of the beam, etc. In addition, the positional relationship of the light projection unit 51 (light source 51a), the beam splitter 55, and the projection optical system 30 is known, so the incident angle of the measuring light ML to the projection optical system 30 can be obtained based on the emission angle and the like. Offset position change amount. On the other hand, the measurement light ML that has passed through the projection optical system 30 is received by the light receiving element 52 a (light receiving surface 53) of the light receiving unit 52. The amount of variation of the measurement light ML obtained by the light receiving element 52a can include components caused by the vibration of each optical element of the projection optical system 30, components caused by environmental fluctuations in the projection optical system 30, and the measurement light ML to the projection optical system 30. The incident angle and other errors are caused by the measurement unit 50 itself. In the case of the present embodiment, the control unit 60 removes the amount of shift position detected by the detection unit 54 from the amount of variation of the measurement light ML on the light receiving element 52a, and based on the value obtained thereby, estimates that the exposure light EL is The amount of variation on the substrate. In this way, based on the value obtained by subtracting the amount of offset position change caused by the measurement unit 50 itself, the amount of change of the exposed light EL on the substrate is estimated, so that the position of the exposed light EL on the substrate can be accurately measured. Fix. <Fourth Embodiment> The fourth embodiment of the present invention will be described. In this embodiment, a modification of the third embodiment in which the detection unit 54 that detects the amount of shift in the offset position is provided in the measurement unit 50 will be described. This embodiment basically inherits the third embodiment, and therefore the differences from the third embodiment will be described below. FIG. 5 is a schematic diagram showing the structure of an exposure apparatus 400 according to a fourth embodiment. Compared with the exposure apparatus 300 of the third embodiment, the exposure apparatus 400 of the present embodiment deletes the light receiving element 54c from the measurement section 50 (detection section 54). That is, the detection unit 54 of the present embodiment is composed of the light receiving element 54b (second light receiving element). The light beam emitted from the light source 51 a of the light projecting unit 51 is branched into two light beams by the beam splitter 55. One of the two light beams branched by the beam splitter 55 is guided into the projection optical system 30 as the measuring light ML, and the other light beam is directed to the light receiving element 54b as the detection light DL for detecting the incident angle of the measuring light ML, etc. guide. Here, the measurement unit 50 of the present embodiment is configured such that the optical path length of the detection light DL received by the light receiving element 54 b is substantially the same as the optical path length of the measurement light ML received by the light receiving element 52 a of the light receiving unit 52. For example, the detection light DL is guided by a plurality of mirrors and received by the light receiving element 54b in a manner substantially the same as the optical path length of the measurement light ML. Specifically, the detection unit 54 is configured such that the optical path of the measurement light ML and the optical path of the detection light DL are substantially the same. The optical path length of the measurement light ML passes through a plurality of optical elements of the projection optical system 30, so it is impractical to connect the optical path of the detection light DL into a straight line in the device. Therefore, it is preferable to use optical elements such as bending mirrors and retroreflectors to obtain the optical path length in a limited space. In addition, the optical element for expanding the optical path length is preferably fixed to the projection optical system 30 relatively, and preferably, it is installed in the projection optical system 30. As a result, the measurement light shift can be measured using the projection optical system 30 alone, and therefore, it can be used for unit inspection as a single projection optical system unit before assembling the exposure apparatus. In such a configuration, assuming that the projection optical system 30 does not generate vibrations of the optical elements or environmental fluctuations, the amount of variation of the measurement light ML on the light receiving element 52a and the variation of the detection light DL on the light receiving element 54b The amount may be the same. That is, the difference between the amount of variation of the measurement light ML obtained by the light receiving element 52a and the amount of variation of the detection light DL obtained by the light receiving element 54b becomes a component due to vibration of each optical element of the projection optical system 30 and environmental fluctuations. Therefore, the control unit 60 removes the amount of variation of the detection light DL on the light receiving element 54 from the amount of variation of the measurement light ML on the light receiving element 52a, and can estimate the amount of variation of the exposed light EL on the substrate based on the value thus obtained. Here, the optical path length being substantially the same refers to a range of such a degree that even if the measurement light ML or the detection light DL fluctuates (for example, the inclination fluctuation), the amount of variation of the light receiving position on the light receiving element can be caused thereby. Treated as roughly the same. This differs depending on the application, and the range thereof varies depending on the measurement accuracy (resolution) of the target position change, the angle of emission of the light beam from the light source 51a, and the like. For example, when the variation in the inclination of the measurement light ML caused by the light source 51a and its fixing system is about 10 μrad and it is desired to set the measurement error based on the optical path length error to 10 nm or less, the optical path length The length error is suppressed to about 1mm. In this case, substantially the same optical path length corresponds to a difference in optical path length of 1 mm or less. On the other hand, when the allowable measurement error based on the optical path length error is as large as about 1 μm, the optical path length error may be about 100 mm. In this case, for approximately the same optical path length, the optical path length difference may be 100 mm or less. Even if the optical path length difference is larger than the previous example, it can be regarded as approximately the same. <Fifth Embodiment> The fifth embodiment of the present invention will be described. In this embodiment, the exposure processing performed by the exposure apparatus described in the first to fourth embodiments will be described. Fig. 6 is a flowchart showing exposure processing. Each step of the flowchart shown in FIG. 6 can be controlled by the control unit 60. In S1, the control unit 60 feeds the substrate W onto the substrate mounting table 40 using a substrate transport mechanism not shown, and causes the substrate mounting table 40 to hold the substrate W. In S2, the control unit 60 performs global alignment processing. For example, the control unit 60 uses an alignment observer (not shown) to measure the position of the alignment mark of the sampling irradiation area among the plurality of irradiation areas of the substrate W, and performs statistical processing on the measurement result. Thereby, the arrangement information of multiple irradiation areas can be obtained. In S3, the control unit 60 sequentially scans and exposes each of the multiple shot areas, and transfers the pattern of the original plate M as a latent image pattern to each shot area (specifically, the photosensitive material (resist) thereon )). In the scanning exposure of each irradiation area in S3, as described in the first to fourth embodiments, the optical characteristics of the projection optical system 30 are measured by the measuring section 50, and the light EL direction of the exposure is performed based on the measurement result. Correction of the irradiation position on the substrate. That is, in the scanning exposure of each irradiation area, the irradiation position of the light EL of the exposure based on the measurement result of the measurement part 50 can be corrected immediately. In S4, the control unit 60 uses a substrate transport mechanism (not shown) to carry out the substrate W from the substrate stage 40. In S5, the control unit 60 determines whether there is a next substrate to be scanned and exposed. If there is the next substrate, return to S1 and perform scanning exposure on the next substrate. On the other hand, it ends without the next substrate. <Embodiment of the article manufacturing method> The article manufacturing method of the embodiment of the present invention is suitable for manufacturing articles such as micro devices such as semiconductor devices and elements having a fine structure, for example. The method of manufacturing an article of this embodiment includes: a step of forming a latent image pattern on a photosensitive agent coated on a substrate using the above-mentioned exposure device (a step of exposing the substrate); and applying the latent image pattern to the substrate The process of developing (processing) is performed. In addition, this manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method of manufacturing an article of the present embodiment is more advantageous than conventional methods in at least one of the performance, quality, productivity, and production cost of the article. (Other embodiments) The present invention can also provide a system or device with a program that realizes one or more functions of the above-mentioned embodiment via a network or a storage medium, and one or more computers in the system or device The processor reads and executes the processing of the program. In addition, it can also be realized by a circuit (for example, ASIC) that realizes one or more functions. Other embodiments The embodiments of the present invention can also be implemented by the following method, that is, software (programs) that perform the functions of the above-mentioned embodiments are provided to a system or device through a network or various storage media, and the system or device The computer or central processing unit (CPU), the micro processing unit (MPU) reads and executes the program. The invention is not limited to the above-mentioned embodiment, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, in order to disclose the scope of the invention, the scope of patent application is attached.
