201105444 六、發明說明： 【發明所屬之技術領域】 本發明是關於一種用來在加工對象物形成改質領域的 雷射加工方法。 【先前技術】 習知的雷射加工方法，是藉由使聚光點匯集於加工對 Q 象物的內部並照射雷射光，而在加工對象物形成改質領域 ’該方法已爲大眾所知悉（例如，參照專利文獻1、2) ° 在如上述的雷射加工方法中，是謀求使用反射型空間光調 變器來調變從雷射光源所射出的雷射光。 [先前技術文獻] [專利文獻] 專利文獻1 :國際公開第2005/ 1 065 64號公報 〇 專利文獻2:日本特開2006 — 68762號公報 【發明內容】 [發明欲解決之課題] 在此，在如上述的習知技術中，由於例如起因於雷射 加工裝置間的機械誤差（所謂裝置間機械誤差）之光學系 統的偏離等，故有「變得難以在加工對象物穩定形成精度 良好的改質領域」之虞。 因此，本發明之課題爲：提供一種「可在加工對象物 -5- 201105444 穩定形成精度良好的改質領域」的雷射加工方法。 [解決課題之手段] 爲了解決上述課題，本發明的雷射加工方法是 聚光點匯集於加工對象物的內部並照射雷射光，而 對象物形成改質領域的雷射加工方法，其特徵爲包 用空間光調變器調變雷射光的調變步驟、和使經調 射光聚光於加工對象物的聚光步驟、及檢測雷射光 的檢測步驟，於調變步驟中，使雷射光入射到空間 器的顯示部所顯示的調變圖型上，且對該雷射光賦 於調變圖型的調變，並根據經檢測步驟所測得之雷 位置，來改變調變圖型的位置。 於該雷射加工方法中，根據雷射光的位置來改 光調變器中調變圖型的位置。因此，即使在例如入 間光調變器的雷射光的位置偏離等的場合中，也可 偏離來改變調變圖型的位置。藉此，可使用空間光 來將雷射光做經常且適當地調變，且可穩定抑制被 加工對象物之雷射光的像差。亦即，可在加工對象 形成精度良好的改質領域。 又，於檢測步驟中，檢測雷射光相對於基準位 變的位置變化量，於調變步驟中，最好是根據經檢 所測得的雷射光的位置變化量，來改變調變圖型的 而使雷射光與調變圖型形成特定位置關係。該場合 適當地發揮上述效果，也就是所謂在加工對象物穩 藉由使 在加工 含：使 變的雷 之位置 光調變 予對應 射光的 變空間 射到空 對應該 調變器 聚光在 物穩定 置所改 測步驟 位置， 中，可 定形成 -6- 201105444 精度良好的改質領域的效果。 此時，於調變步驟中’有時使用有關調變圖型之位置 變化量的數據表，來改變調變圖型的位置’而該調變圖型 之位置變化量，是關聯對應於該雷射光的位置變化量。又 ，於調變步驟中，有時則根據雷射光的位置變化量算出調 變圖型的位置變化量，且對應於所算出之調變圖型的位置 變化量來改變調變圖型之位置。 Q 又，就適當地達到上述作用效果的構成而言，具體而 言，可列舉下述構成：調變圖型是表示顯示部之複數像素 的每一個的折射率，於調變步驟中，使調變圖型移動到特 定位置，並對應於經移動的調變圖型來運算複數像素的折 射率，且控制像素的折射率使其形成對應於該運算所得的 値。 此時，使調變圖型移動的移動量，有時爲顯示部的1 像素尺寸以下。 〇 [發明效果] 根據本發明，可在加工對象物穩定形成精度良好的改 質領域。 【實施方式】 以下’將針對本發明之適合的實施形態，參照圖面詳 細地說明。而且，於各圖中對相同或相當的元件給予相同 符號’並省略重複的說明。此外，「上」' 「下」、「左 201105444 」、「右」之用語是根據圖面所顯示之狀態的簡便用語° 於本實施形態的雷射加工裝置中’是藉由使聚光點匯 集於加工對象物的內部並照射雷射光’而在加工對象物形 成改質領域。因此’首先’針對藉由本實施形態的雷射加 工裝置而形成的改質領域，參照第1圖〜第6圖進行說明。 如第1圖所示，雷射加工裝置100具備：將雷射光L脈 衝振盪的雷射光源101、和被配置成使雷射光L的光軸（光 路徑）之方向可90°轉變的分光鏡103、及用來將雷射光L 聚光的聚光用透鏡1〇5。又，雷射加工裝置100具備：用來 支撐被以聚光用透鏡105聚光的雷射光L照射之加工對象物 1的支撐台107、和用來讓支撐台107朝X、Y、Z軸方向移 動的台111、和控制用來調節雷射光L的輸出或脈衝幅度等 之雷射光源1 〇 1的雷射光源控制部1 02、及控制台1 1 1之移 動的台控制部1 1 5。 於該雷射加工裝置100中，從雷射光元101所射出的雷 射光L是藉由分光鏡103使其光軸的方向90°轉變，且藉由 聚光用透鏡1〇5被聚光在裝載於支撐台1〇7上之加工對象物 1的內部。同時，使台1 1 1移動，且使加工對象物丨相對於 雷射光L而沿著切斷預定線5相對移動。藉此，可於加工對 象物1形成沿著切斷預定線5的改質領域。 加工對象物1是採用半導體材料或壓電材料等，如第2 圖所示’在加工對象物1，設定有用來切斷加工對象物1的 切斷預定線5。切斷預定線5是呈直線狀延伸的假想線。於 加工對象物1的內部形成改質領域的場合，如第3圖所示， -8 - 201105444 在使聚光點P匯集於加工對象物1之內部的狀態下’使雷射 光L沿著切斷預定線5 (亦即，朝第2圖中的箭號A方向）相 對地移動。藉此，如第4圖〜第6圖所示’改質領域7將沿 著切斷預定線5而形成在加工對象物1的內部’且使沿著切 斷預定線5所形成的改質領域7成爲切斷起點領域8 ° 此外，聚光點P是指雷射光L的聚光之處。又’切斷預 定線5不限於直線狀，亦可爲曲線狀，且不限於假想線亦 Q 可爲實際畫在加工對象物1之表面3的線。又’改質領域7 有時是被連續地形成，有時是被斷續地形成。又’改質領 域7可爲列狀或點狀，重點是：改質領域7只要是至少被形 成在加工對象物1的內部即可。又，有時改質領域7在起點 形成龜裂，龜裂及改質領域7也可露出加工對象物1的外表 面（表面、背面、或者是外周面）。 附帶說明，在此，雷射光L透過加工對象物1並特別被 吸收在加工對象物1之內部的聚光點附近，藉此，在加工 Q 對象物1形成改質領域7 (亦即，內部吸收型雷射加工）。 因此，由於在加工對象物1的表面3雷射光L幾乎不被吸收 ，故加工對象物1的表面3不會熔融。一般而言，在從表面 3熔融並去除而形成孔或溝等之去除部的場合（表面吸收 型雷射加工），加工領域則從表面3側開始緩緩地朝背面 側進行。 但是，使用本實施形態的雷射加工裝置所形成的改質 領域，是所謂密度、折射率、機械性強度或其他的物理特 性成爲與四周不同狀態的領域。改質領域，例如有：熔融 • 9 - 201105444 處理領域、裂紋（crack )領域、絕緣破壞領域、折射率變 化領域等，也有上述領域混合存在的領域。又’就改質領 域而言，有著：在加工對象物的材料中，改質領域的密度 相較於非改質領域的密度爲，經變化的領域、或形成晶格缺 陷（lattice defect)的領域（上述領域亦統稱爲高密度移 轉領域）。 又，熔融處理領域或折射率變化領域、改質領域的密 度相較於非改質領域的密度爲經變化的領域、形成晶格缺 陷的領域，有時更進一步在上述領域的內部、或改質領域 與非改質領域之界面內含著龜裂（裂痕、微細裂紋）。內 含的龜裂有時遍及改質領域全面、或有時只形成一部份或 複數部份。作爲加工對象物1可列舉包含如矽、玻璃、 1^1^03或藍寶石（八1203)、或者由上述所構成者。 接著，針對本發明的一實施形態詳細說明。 第7圖爲顯示實施本發明的一實施形態的雷射加工方 法之雷射加工裝置的槪略構成圖。如第7圖所示，雷射加 工裝置20 0在機體231內具備有：雷射光源202、反射型空 間光調變器203、4f光學系統241及聚光光學系統204。 雷射光源202是用來射出雷射光L。可採用例如光纖雷 射作爲雷射光源202。此處的雷射光源202被以螺絲等固定 在機體231的頂板23 6，以使雷射光朝水平方向（X方向） 射出。 反射型空間光調變器203是用來調變從雷射光源202所 射出的雷射光L。作爲反射型空間光調變器203可採用例如 -10- 201105444 :反射型液晶（LCOS : Liquid Crystal on Silicon)的空間 光調變器（SLM : Spatial Light Modulator)。該反射型空 間光調變器203，是一邊使從水平方向入射的雷射光L相對 於水平方向朝斜上方反射，並採用「使聚光於加工對象物 1內部之雷射光L (也就是指在聚光位置的雷射光L)的像 差成爲特定像差以下（理想爲接近零）」的方式來調變。 第8圖爲顯示第7圖的雷射加工裝置之反射型空間光調 Q 變器的局部剖面圖。如第8圖所示，反射型空間光調變器 2 03具備：矽基板213、驅動電路層914、複數個像素電極 214、介電質多層膜鏡（dielectric multilayer mirror)等 的反射膜215、配向膜999a、液晶層（顯示部）216、配向 膜999b、透明導電膜217、及玻璃基板等的透明基板218, 而上述各構件是依上述的順序所層積。 透明基板218具有沿著XY平面的表面218a，且由該表 面21 8a構成反射型空間光調變器203的表面。透明基板218 Q 主要含有如玻璃等的光透過性材料。透明基板218是使已 從反射型空間光調變器203的表面218a入射之特定波長的 雷射光L，朝反射型空間光調變器2 03的內部透過。透明導 電膜217被形成在透明基板21 8的背面上，且主要由含有雷 射光L透過的導電性材料（例如ITO )所構成。 複數的像素電極2 1 4是按照複數之像素的排列被排列 成二維狀，且沿著透明導電膜2 1 7被排列在矽基板2 1 3上。 複數的像素電極2 1 4是由例如鋁等的金屬材料所形成。又 ，電極214的表面214a被加工成平坦且光滑的表面。複數 -11 - 201105444 的像素電極214是由設在驅動電路層914的主動-矩陣（ active-matrix)電路所驅動。 主動-矩陣電路被設置在複數的像素電極214與矽基板 2 13之間，對應於欲從反射型空間光調變器203輸出的影像 來控制往各像素電極214的外加電壓。上述的主動-矩陣電 路具有：第1驅動電路與第2驅動電路，該第1驅動電路是 用來控制排列在例如未圖示的X軸方向之各像素列的外加 電壓，第2驅動電路則是用來控制排列在Y軸方向之各像素 列的外加電壓。主動-矩陣電路是藉由控制部25 0，以雙方 的驅動電路對所指定之像素的像素電極214施加特定電壓 所構成。 此外，配向膜999a、999b是被配置於液晶層216的兩 端面，且將液晶分子群排列成一定方向。配向膜999a、 999b是藉由例如稱爲聚醯亞胺的高分子材料所形成。就配 向膜999a、999b而言，可以採用對與液晶層216之間的接 觸面施以摩擦處理等的膜。 液晶層216被配置在複數的像素電極214與透明導電膜 217之間，對應於由各像素電極214與透明導電膜217所形 成的電場來調變雷射光L。亦即，藉由主動-矩陣電路或對 像素電極214施加電壓，可在透明導電膜21 7與該像素電極 2 1 4之間形成電場。 該電場，是以對應於各個厚度的比例，而分別施加於 反射膜2 1 5及液晶層2 1 6。接著，對應於被施加於液晶層 2 1 6的電場大小來改變液晶分子2 1 6 a的排列方向。一旦雷 -12- 201105444 射光L透過透明基板218及透明導電膜217入射到液晶層216 ，該雷射光L會在通過液晶層216時藉由液晶分子216a而調 變，且在反射膜215中反射之後’再藉由液晶層216調變後 被取出。 此時，藉由控制部250 (後述）對與透明導電膜21 7對 向之各像素電極部214a的每一個施加電壓’且對應於該電 壓，來改變在液晶層216中與透明導電膜21 7對向的各像素 q 電極部214a所挾持之部分的折射率（改變對應於各像素位 置之液晶層2 1 6的折射率）。藉由該折射率的改變，對應 於所施加的電壓，使雷射光L的相位在液晶層2 1 6的每個像 素產生變化。換言之，可藉由液晶層216賦予每一個像素 對應於全像（hologram )圖型的相位調變（亦即，作爲賦 予調變的全像圖型的調變圖型被顯示於空間光調變器203 )。其結果爲，可調整入射到反射型空間光調變器203被 調變且反射之雷射光L的波面，於構成該雷射光L的各光線 Q 中，在垂直於進行方向的特定方向之成分的相位上產生的 偏離，可調整該雷射光L的強度、振幅、相位、偏光等之 至少一項。 回到第7圖中，4f光學系統241是用來調整藉由反射型 空間光調變器203所調變的雷射光L的波面形狀。該4f光學 系統241具有第1透鏡24 la及第2透鏡24lb。 透鏡241a、24 lb是如下述構成般地被配置在反射型空 間光調變器203與聚光光學系統204之間。亦即，於透鏡 241a、241b中，將反射型空間光調變器203與第1透鏡24la -13 - 201105444 的距離設爲第1透鏡24 la的焦點距離fl，將聚光光學系統 204與第2透鏡241b的距離設爲透鏡24lb的焦點距離f2，第 1透鏡24la與第2透鏡24lb的距離成爲fl+f2，且將第】透鏡 241a與第2透鏡241b配置在反射型空間光調變器203與聚光 光學系統204之間以形成兩側遠心光學系統。 該4f光學系統241可以抑制：經反射型空間光調變器 2 03所調變的雷射光L，因空間傳播而使波面形狀產生變化 ，且像差增大的情形。於此處的4 f光學系統2 4 1中，調整 雷射光L以使入射到聚光光學系統204的雷射光L成爲平行 光。 聚光光學系統2 04，是用來將由4f光學系統24 1所調變 的雷射光L’聚光於加工對像物1的內部。該聚光光學系統 2〇4是包含複數的透鏡所構成，經由包含壓電元件等所構 成的驅動單位232設置在機體231的底板233。 又’雷射加工裝置200在機體231內具備：用來觀察加 工對象物1之表面3的表面觀察單位211、和用來微調整聚 光光學系統204與加工對象物距離的AF ( Auto Focus ) 單位2 1 2。 表面觀察單位211具有：射出可見光VL1的觀察用光源 211a、與接收在加工對象物1的表面3所反射之可見光VL1 的反射光VL2並予以檢測的檢測器2 1 1 b。於表面觀察單位 211中’從觀察用光源211a所射出的可見光VL1可在鏡208 及分光鏡2〇9、210、238反射/透過，且使用聚光光學系 統204來朝加工對象物聚光。接著，於表面觀察單位211中 -14- 201105444 ，在加工對象物1的表面3所反射的反射光VL2在由聚光光 學系統2 04所聚光並在分光鏡238、210透過/反射之後， 透過分光鏡209以檢測器2 lib來接收光。 AF單位212是藉由射出AF用雷射光LB1，且接收在加 工對象物1的表面3所反射之AF用雷射光LB1的反射光LB2 並予以檢測，來取得沿著切斷預定線5之表面3的變位數據 。而且，AF單位212是當形成改質領域7時，根據所取得的 Q 變位數據來驅動驅動單位232，使聚光光學系統204沿著加 工對象物1之表面3的彎曲在其光軸方向上來回移動。 再者’雷射加工裝置200具備用來控制該雷射加工裝 置200的控制部250，該控制部250由CPU、ROM、RAM等 所構成。控制部250控制雷射光源202，且調節從雷射光源 2 02所射出之雷射光L的輸出或脈衝幅度等。又，控制部 250是當形成改質領域7時，控制機體23 1或台1 1 1的位置、 及驅動單位232的驅動，以使雷射光L的聚光點p從加工對 〇 象物1的表面3位於特定的距離且沿著切斷預定線5相對地 移動。 又，控制部250是當形成改質領域7時，對在反射型空 間光調變器203中的像素電極214之各電極部214a與透明電 極膜217施加特定電壓，來改變反射型空間光調變器2〇3中 的液晶層2 1 6之各元件的折射率，且在液晶層2丨6顯示特定 的調變圖型。其結果成爲：從反射型空間光調變器203所 射出並聚光於加工對象物1之內部的雷射光L的像差，可控 制在特定的像差以下（詳細敘述於後）。 -15- 201105444 在使用如上述構成的雷射加工裝置200來切斷加工對 象物1的場合’首先’在加工對象物1的背面，貼附有例如 膨脹帶（expanded tape) ’並將該加工對象物！載置於台 11 1上。 接著’使聚光點從加工對象物1的表面3匯集於矽晶圓 1 1的內部’並由雷射光源202照射雷射光L (第9圖的S 1 ) 。所射出的雷射光L在機體231內朝水平方向進行後，藉由 鏡205a朝下方反射，藉由衰減器207來調整光強度。接著 ，雷射光L是藉由鏡205b朝水平方向反射，且藉由光束均 質機（beamhomogenizer) 260來使強度分布均勻化並入射 到反射型空間光調變器203。 已入射到反射型空間光調變器203的雷射光L是以特定 像差以下的像差來調變，使雷射光L聚光於加工對象物1的 內部（S4 )。具體而言，所入射的雷射光L是透過在液晶 層216所表示的調變圖型並對應於該調變圖型來調變，且 面對水平方向朝斜上方射出。接著，雷射光L是藉由鏡 2〇6a朝上方反射後，藉由λ /2波長板2M使偏光方向改變 成沿著切斷預定線5的方向，藉由鏡2 0 6 b朝水平方向反射 而入射到4 f光學系統2 4 1。 入射到4f光學系統24 1的雷射光L是調整波面形狀使其 以平行光入射到聚光光學系統204 ( S5 )。具體而言’雷 射光L是透過第1透鏡241a收束，藉由鏡219向下方反射’ 經過共焦點0散發，且透過第2透鏡24 lb使其成爲平行光後 再被收束。 -16 - 201105444 其後’雷射光L依序透過分光鏡210、218入射到聚光 光學系統2 04，藉由聚光光學系統204聚光於被載置在台 111上的加工對象物1的內部（S6)。藉此，沿著切斷預定 線5在加工對象物1的內部形成改質領域7。接著，藉由擴 張膨脹帶將改質領域7作爲切斷的起點，且沿著切斷預定 線5切斷加工對象物1，使複數的半導體晶片彼此隔開。 在此，本實施形態的雷射加工裝置200是具備PSD ( Q Position Sensitive Detector :半導體位置檢測元件）270a 、270b來作爲檢測雷射光L之位置（pointing)的光感測器 。上述的PSD 270a、270b被連接於控制部250，且將所測 得的雷射光L之位置資訊輸出到控制部250。 PSD 270a是在雷射光L的光路徑中被連接於鏡205a與 衰減器207之間。在此，PSD 270a是使被鏡205a所反射的 雷射光L，以鏡271、272依序反射後導光到PSD 270a。藉 此，PSD 270a是將經衰減器207調整光強度之前的雷射光L Q 的光點中的重心位置（中心位置）作爲座標値來進行二維 檢測。 PSD 27 Ob是在雷射光L的光路徑中被連接於鏡205b與 光束均質機260之間。在此，PSD 270b是將被鏡205b所反 射的雷射光L，以鏡273、274依序反射後導光到PSD 270b 。藉此，PSD 270b是將經光束均質機260對強度分布均勻 化之前的雷射光L的光點中的重心位置作爲座標値來進行 二維檢測。 第10圖爲顯示藉由PSD所測出的雷射光位置資訊之一 -17- 201105444 例的示意圖。於圖中之例示’所測得之雷射光L的座標値Q ，是採用將初期狀態（初期調整時）之雷射光L的重心位 置作爲原點（基準位置）的座標軸來設定。如第1〇圖所示 ，根據PSD 270a、270b來檢測雷射光L的座標値，換言之 ，是檢測相對於雷射光L之基準値（初期値）的位置變化 量。 因此，於本實施形態中，藉由PSD 270a、270b來經常 監控從雷射光源202所射出且入射到反射型空間光調變器 203之前雷射光L的座標値Q(S2)。接著，根據從PSD 2 7 0a、270b之至少一方所輸入之雷射光L的座標値Q，藉由 控制部250控制對反射型空間光調變器203的電極部214a及 透明導電膜217施加的電壓，使顯示於液晶層216的調變圖 型的位置自動地改變（校正）（S3)。 具體而言，是將關於與雷射光L之座標値有關連的調 變圖型之位置變化量的數據表，預先收納於控制部250。 如第1 1圖所示，於此處的數據表Tb中，以使雷射光L與調 變圖型保持特定位置關係的方式（例如，使彼此的重心一 致），使雷射光L的座標値Q和調變圖型的位置變化量，與 每個X及Y座標（參照第8圖）作連結。接著，使用該數據 表Tb ’從由PSD 270a、270b所測得之雷射光L的座標値導 出調變圖型的位置變化量，使調變圖型的位置僅改變該位 置變化量。 或者，亦可根據雷射光L的座標値，藉由下式（1 )來 算出調變圖型的位置變化量，使調變圖型的位置僅改變位 -18- 201105444 置變化量。 Δ X = PSDxxa △ Y = P S D yxb ...... ( 1 ) 其中，△ x :調變圖型的位置變化量（X座標） △ Y :調變圖型的位置變化量（Y座標） PSDx :雷射光L的座標値（X座標） PSDy :雷射光L的座標値（Y座標） Q a、b:特定的設定値 藉此，使入射到液晶層2 1 6的雷射光L與顯示於液晶層 216之調變圖型Η的位置關係以1像素程度的高精度校準成 特定位置關係。其結果成爲：反射型空間光調變器203， 以使聚光於加工對象物1之內部的雷射光L的像差成爲在特 定的像差以下的方式，使雷射光L能確實且精度良好地調 變 0 第1 2圖爲顯示在液晶層所顯示的調變圖型與入射到液 Q 晶層的雷射光之關係的示意圖。於第12圖中，顯示從Ζ軸 方向（參照第8圖）觀看時的液晶層216，調變圖型Η是圓 形狀。如第1 2 ( a )圖所示，由於例如光學系統的偏離等 ，即使在所顯示之調變圖型Η的重心與已入射之雷射光L的 重心彼此偏離且不一致的場合，如第1 2 ( b )圖所示，根 據雷射光L的座標値來自動地移動調變圖型Η的位置，使調 變圖型Η的重心與雷射光L的重心成爲一致。 以上，於本實施形態中，使在反射型空間光調變器 203中之調變圖型Η的位置根據雷射光L的位置來改變，且 -19 - 201105444 使雷射光L與調變圖型Η的關係位置以1像素程度的高精度 校準。藉此，可使用反射型空間光調變器203來經常且適 當地調變雷射光L，且可穩定抑制聚光於加工對象物1之雷 射光L的像差。 因此，根據本實施形態，可在加工對象物1穩定形成 精度良好的改質領域7。其結果，可抑制裝置間的機械誤 差，且可經常地維持高加工品質。 第13圖爲顯示於加工對象物形成改質領域，且經切斷 時之切斷面狀態的放大照片圖。另外，反射型空間光調變 器203的像素尺寸設爲2〇βιηχ20μιη，像素數是被設成： 橫（X)方向792，縱（Υ)方向600的792x600。圖中顯示 在液晶層216中使作爲調變圖型之像差校正圖型Η的位置沿 著X方向改變時的圖示。 於第13圖所示之例中可得知，當調變圖型Η的位置變 化量爲〇(基準位置）時及+4" m時，雷射光L與調變圖型 Η的位置關係成爲特定位置關係，且切斷面的品質爲良好 。又可得知，當調變圖型Η的位置變化量爲+ 24//m時，切 斷面的品質爲不良，上述情況以外時，切斷面的品質爲普 通。此外，藉由如第1 3圖所示之例可得知，在形成精度良 好之改質領域7的場合，雷射光L與調變圖型Η的位置關係 中，高精度的校準是重要的。 又，以1像素以下的移動量（換言之，縱及橫方向個 別之像素尺寸以下的移動量）可充分地顯現出效果。在藉 由該1像素以內之範圍內的移動無法得到良好的加工品質 -20- 201105444 的場合中，需要再調整光學系統的設定。 針對1像素以下之調變圖型的移動進行說明。第15圖 爲用來說明1像素以下之調變圖型的移動之圖示。於該第 15圖中’以長條圖顯示對應於在作爲特定之X方向的—方 向的各像素（液晶）中之調變圖型（關於例如像差校正等 )的折射率。換言之’以複數像素的每一個的折射率表示 調變圖型。在此，爲了說明’以一維圖型來簡略化說明二 0 維圖型。 首先，如第15(a)圖所示，設定表示各像素的折射 率的調變圖型曲線W1 (於第13圖的場合，像差校正圖型 曲線）。而且’因以一維來說明，故各像素的折射率是以 調變圖型曲線來表現’但在二維的場合中，該調變圖型曲 線是表示各像素的每一個折射率的調變圖型。 接著’如第1 5 ( b )圖所示，將調變圖型曲線w 1僅以 特定的移動量（如第13圖的場合般，例如+4;/m)往右方 Q 向移動。接著，再計算對應於已移動的調變圖型曲線W2 之各像素的折射率（W2中的圓形記號）。之後，對各像 素賦予對應於經再計算之値的折射率。在例如第1 3圖所示 之例的場合中，對應於各像素所賦予的折射率設爲8bit ( 2 5 6色階）。 如以上所述進行調變圖型Η的移動。因此，即使在1像 素以下的移動亦可進行校正，且可更精密地使調變圖型（ 像差校正圖型）移動。 以上，雖已針對本發明適合的實施形態進行說明，但 -21 - 201105444 本發明並不限於上述實施形態。例如，上述實施形態是具 備PSD 270a、270b來作爲檢測雷射光L之位置的裝置，但 亦可僅具備上述之任何一方。 不僅如此，亦可具備其他的PSD取代PSD270a、270b 或者添加，例如，第14圖所示，也可在雷射光l的光路徑 中於分光鏡23 8與聚光光學系統2〇4之間連接pSD 370。在 該場合中，已透過分光鏡238的雷射光L，以鏡371、372依 序反射且導光到P S D 3 7 0。因此，可檢測雷射光L聚光於加 工對象物1之前的位置。藉此，在雷射光L的光學系統產生 偏離等的場合，必須檢測雷射光L之位置的偏離來改變調 變圖型Η的位置，且使雷射光L與調變圖型Η的位置關係形 成正確。 又，於上述實施形態中，雖具備光束均質機2 60，且 使用光束均質機260使強度分布已均勻化的雷射光L入射到 反射型空間光調變器203，但亦可取而代之，具備光束擴 展器，使經光束擴展器擴大了光束路徑的雷射光L入射到 反射型空間光調變器203。在該場合中，爲了將雷射光L的 位置檢測高精度化，最好以P SD來檢測使用光束擴展器擴 大光束路徑前之雷射光L的位置。 又，在形成改質領域7時的雷射光入射面並不限定於 加工對象物1的表面3，亦可爲加工對象物1的背面。又， 於上述實施形態中，當然可以沿著切斷預定線5形成複數 列的改質領域7。 -22- 201105444 產業上的可利用性 根據本發明，可在加工對象物上穩定形成精度良好的 改質領域。 【圖式簡單說明】 [第1圖]用於形成改質領域之雷射加工裝置的槪略構成 圖。 Q [第2圖]成爲形成改質領域之加工對象物的俯視圖。 [第3圖]沿著第2圖之加工對象物的ΠΙ-ΙΙΙ線之剖面圖 〇 [第4圖]雷射加工後之加工對象物的俯視圖。 [第5圖]沿著第4圖之加工對象物的V-V線之剖面圖。 [第6圖]沿著第4圖之加工對象物的VI-VI線之剖面圖。 [第7圖]顯示本發明的一實施形態之雷射加工裝置的槪 略構成圖。 Q [第8圖]反射型空間光調變器的局部剖面圖。 [第9圖]顯示雷射加工方法之順序的流程圖。 [第10圖]顯示藉由PSD所測得之雷射光的位置資訊之 一例的示意圖。 [第1 1圖]顯示關於雷射光的座標値與調變圖型的位置 變化量之數據表的圖式。 [第12圖]顯示於液晶層所表示的調變圖型與入射到液 晶層的雷射光之關係的示意圖。 [第I3圖]顯示在加工對象物形成改質領域已切斷時之 -23- 201105444 切斷面狀態的放大照片圖。 [第1 4圖]顯示第7圖之雷射加工裝置的其他例的槪略構 成圖。 [第15圖]用來說明1像素以下之調變圖型的移動的圖式 【主要元件符號說明】 1 :加工對象物 7 :改質領域 203 :反射型空間光調變器（空間光調變器） 216:液晶層（顯7Γ；部） Η :調變圖型 L :雷射光 Ρ :聚光點 -24-201105444 VI. Description of the Invention: [Technical Field] The present invention relates to a laser processing method for forming a modified object in a processed object. [Prior Art] The conventional laser processing method is to form a modified field in the object to be processed by bringing the light collecting point into the interior of the processing object and irradiating the laser light. (For example, refer to Patent Documents 1 and 2) ° In the laser processing method as described above, it is intended to modulate the laser light emitted from the laser light source using a reflective spatial light modulator. [Prior Art Document] [Patent Document 1] Patent Document 1: International Publication No. 2005/1 065 64 pp. Patent Document 2: JP-A-2006-68762 [Summary of the Invention] [Problems to be Solved by the Invention] Here, In the above-described conventional technique, for example, due to a deviation of an optical system caused by a mechanical error (a so-called mechanical error between devices) between the laser processing apparatuses, it is difficult to stably form an object to be processed with high precision. The key to the field of upgrading. Therefore, an object of the present invention is to provide a laser processing method which is "a field of improvement in which the object to be processed can be stably formed with high precision". [Means for Solving the Problem] In order to solve the above-described problems, the laser processing method of the present invention is characterized in that a laser beam is collected in a processing object and irradiated with laser light, and the object is formed into a laser processing method in a modified field. a modulation step of modulating the laser light by the spatial light modulator, a concentrating step of concentrating the modulating light on the object to be processed, and a detecting step of detecting the laser light, and making the laser light incident in the modulating step Go to the modulation pattern displayed on the display portion of the space device, and assign the laser light to the modulation pattern of the modulation pattern, and change the position of the modulation pattern according to the position of the lightning detected by the detecting step. . In the laser processing method, the position of the modulation pattern in the modulator is changed according to the position of the laser light. Therefore, even in the case where, for example, the position of the laser beam entering the optical modulator is deviated or the like, the position of the modulation pattern can be changed by shifting. Thereby, the spatial light can be used to constantly and appropriately modulate the laser light, and the aberration of the laser light of the object to be processed can be stably suppressed. That is, it is possible to form a highly accurate field of modification in the object to be processed. Further, in the detecting step, detecting a position change amount of the laser light with respect to the reference position, in the step of modulating, it is preferable to change the modulation pattern according to the position change amount of the laser light measured by the inspection. The laser light and the modulation pattern form a specific positional relationship. In this case, the above-described effects are appropriately exhibited, that is, the object to be processed is stabilized by the variable space in which the position of the ray is changed to the corresponding ray, and the modulator is condensed on the object. Stabilize the position of the test step, in which the effect of the modified field of -6-201105444 can be determined. At this time, in the modulation step, "the data table of the position change amount of the modulation pattern is sometimes used to change the position of the modulation pattern" and the position change amount of the modulation pattern is associated with the The amount of change in the position of the laser light. Further, in the modulation step, the position change amount of the modulation pattern may be calculated based on the position change amount of the laser light, and the position of the modulation pattern may be changed corresponding to the position change amount of the calculated modulation pattern. . In addition, a configuration in which the above-described effects are appropriately achieved is specifically a configuration in which the modulation pattern is a refractive index indicating each of a plurality of pixels of the display unit, and in the modulation step, The modulation pattern is moved to a specific position, and the refractive index of the complex pixel is calculated corresponding to the shifted modulation pattern, and the refractive index of the pixel is controlled to form a 对应 corresponding to the operation. At this time, the amount of movement of the modulation pattern may be equal to or less than the 1-pixel size of the display unit. [Effect of the Invention] According to the present invention, it is possible to achieve a field of improvement in which the object to be processed is stably formed with high precision. [Embodiment] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding elements are denoted by the same reference numerals, and the repeated description is omitted. In addition, the terms "upper", "lower", "left 201105444" and "right" are simple terms according to the state displayed on the drawing. In the laser processing apparatus of the present embodiment, The inside of the object to be processed is collected and irradiated with laser light' to form a modified field in the object to be processed. Therefore, the first modification of the field of the laser processing apparatus according to the present embodiment will be described with reference to Figs. 1 to 6 . As shown in Fig. 1, the laser processing apparatus 100 includes a laser beam 101 that oscillates the laser beam L and a beam splitter that is arranged to shift the direction of the optical axis (light path) of the laser beam L by 90°. 103. A collecting lens 1〇5 for collecting the laser light L. Further, the laser processing apparatus 100 includes a support table 107 for supporting the object 1 to be irradiated with the laser light L collected by the collecting lens 105, and a support table 107 for the X, Y, and Z axes. The stage 111 that moves in the direction, and the stage control unit 1 that controls the laser light source control unit 102 of the laser light source 1 〇1 for adjusting the output or pulse width of the laser light L, and the movement of the console 1 1 1 5. In the laser processing apparatus 100, the laser beam L emitted from the laser beam 101 is converted by the beam splitter 103 in the direction of the optical axis by 90°, and is concentrated by the collecting lens 1〇5. The inside of the object 1 to be mounted on the support table 1〇7. At the same time, the stage 1 1 1 is moved, and the object to be processed is relatively moved along the line to cut 5 with respect to the laser light L. Thereby, the modified object area along the line to cut 5 can be formed in the processed object 1. In the object to be processed 1, a semiconductor material, a piezoelectric material, or the like is used. As shown in Fig. 2, the cutting target line 5 for cutting the object 1 is set in the object 1 to be processed. The cutting planned line 5 is an imaginary line extending in a straight line. When the modified region is formed in the inside of the object 1 as shown in Fig. 3, -8 - 201105444, in the state where the condensed spot P is collected inside the object 1 is made, the laser light L is cut along the cut surface. The broken predetermined line 5 (i.e., in the direction of the arrow A in Fig. 2) relatively moves. Thereby, as shown in FIGS. 4 to 6 , the 'modified region 7 is formed inside the object 1 along the line to cut 5 ' and the reform formed along the line to cut 5 is formed. The field 7 becomes the starting point of the cutting direction 8 °. Further, the collecting point P refers to the spot where the laser light L is concentrated. Further, the cutting predetermined line 5 is not limited to a straight line, and may be curved, and is not limited to the imaginary line. Q may be a line actually drawn on the surface 3 of the object 1 to be processed. Further, the field of reforming 7 is sometimes formed continuously, and sometimes it is formed intermittently. Further, the reforming field 7 may be in the form of a column or a dot, and it is important that the reforming field 7 is formed at least in the inside of the object 1 to be processed. Further, in the modified region 7, cracks may be formed at the starting point, and the cracked and modified region 7 may also expose the outer surface (surface, back surface, or outer peripheral surface) of the object 1 to be processed. Incidentally, here, the laser beam L is transmitted through the object 1 and is particularly absorbed in the vicinity of the light-converging point inside the object 1 to form the modified region 7 (that is, the inside). Absorption laser processing). Therefore, since the laser light L is hardly absorbed on the surface 3 of the object 1 to be processed, the surface 3 of the object 1 does not melt. In general, when the surface 3 is melted and removed to form a removed portion such as a hole or a groove (surface absorption type laser processing), the processing area is gradually progressed from the surface 3 side toward the back side. However, the field of modification formed by the laser processing apparatus of the present embodiment is a field in which density, refractive index, mechanical strength, or other physical characteristics are different from the surrounding state. In the field of upgrading, for example: melting • 9 - 201105444 Processing field, crack field, dielectric breakdown field, refractive index change field, etc., there are also fields in which the above fields are mixed. In addition, in the field of upgrading, there is: in the material of the object to be processed, the density of the modified field is compared with the density of the non-modified domain, the changed field, or the formation of a lattice defect. Fields (the above areas are also collectively referred to as high-density transfer areas). Moreover, the density of the field of fusion treatment or the field of refractive index change, the density of the field of modification is a field of change, a field of formation of lattice defects, and sometimes further within the above-mentioned fields, or The interface between the qualitative and non-modified areas contains cracks (cracks, fine cracks). The cracks included are sometimes comprehensive or sometimes only partially or plural in the field of modification. The object to be processed 1 includes, for example, enamel, glass, 1^1^03 or sapphire (eight 1203), or the above. Next, an embodiment of the present invention will be described in detail. Fig. 7 is a schematic block diagram showing a laser processing apparatus for carrying out a laser processing method according to an embodiment of the present invention. As shown in Fig. 7, the laser processing apparatus 20 includes a laser light source 202, a reflection type spatial light modulator 203, a 4f optical system 241, and a collecting optical system 204 in the body 231. The laser light source 202 is for emitting laser light L. For example, a fiber laser can be employed as the laser source 202. Here, the laser light source 202 is fixed to the top plate 23 of the body 231 by screws or the like to emit the laser light in the horizontal direction (X direction). The reflective spatial light modulator 203 is used to modulate the laser light L emitted from the laser light source 202. As the reflective spatial light modulator 203, for example, -10-201105444: LCOS (Liquid Crystal on Silicon) spatial light modulator (SLM) can be used. In the reflective spatial light modulator 203, the laser light L incident from the horizontal direction is reflected obliquely upward with respect to the horizontal direction, and "the laser light L that is collected in the inside of the object 1 is used (that is, The aberration of the laser light L) at the condensing position is modulated so as to be equal to or less than a specific aberration (ideally close to zero). Figure 8 is a partial cross-sectional view showing a reflective spatial light modulation Q-variator of the laser processing apparatus of Figure 7. As shown in FIG. 8, the reflective spatial light modulator 203 includes a reflective film 215 such as a germanium substrate 213, a driving circuit layer 914, a plurality of pixel electrodes 214, and a dielectric multilayer mirror. The alignment film 999a, the liquid crystal layer (display portion) 216, the alignment film 999b, the transparent conductive film 217, and the transparent substrate 218 such as a glass substrate are laminated in the above-described order. The transparent substrate 218 has a surface 218a along the XY plane, and the surface of the reflective spatial light modulator 203 is constituted by the surface 21 8a. The transparent substrate 218 Q mainly contains a light transmissive material such as glass. The transparent substrate 218 transmits the laser light L of a specific wavelength that has entered from the surface 218a of the reflective spatial light modulator 203 toward the inside of the reflective spatial light modulator 203. The transparent conductive film 217 is formed on the back surface of the transparent substrate 218, and is mainly composed of a conductive material (e.g., ITO) that transmits the laser light L. The plurality of pixel electrodes 2 1 4 are arranged in a two-dimensional shape in accordance with the arrangement of the plurality of pixels, and are arranged on the ruthenium substrate 2 1 3 along the transparent conductive film 2 17 . The plurality of pixel electrodes 2 14 are formed of a metal material such as aluminum. Again, surface 214a of electrode 214 is machined into a flat and smooth surface. The pixel electrode 214 of the complex -11 - 201105444 is driven by an active-matrix circuit provided in the driver circuit layer 914. The active-matrix circuit is disposed between the plurality of pixel electrodes 214 and the germanium substrate 2 13 to control the applied voltage to the respective pixel electrodes 214 in correspondence with the image to be output from the reflective spatial light modulator 203. The active-matrix circuit includes a first drive circuit for controlling an applied voltage of each pixel column arranged in an X-axis direction (not shown), and a second drive circuit, and the second drive circuit It is used to control the applied voltage of each pixel column arranged in the Y-axis direction. The active-matrix circuit is constituted by the control unit 25 0 that applies a specific voltage to the pixel electrodes 214 of the designated pixels by the drive circuits of both sides. Further, the alignment films 999a and 999b are disposed on both end faces of the liquid crystal layer 216, and the liquid crystal molecules are arranged in a predetermined direction. The alignment films 999a and 999b are formed of, for example, a polymer material called polyimine. For the alignment films 999a and 999b, a film for applying a rubbing treatment or the like to the contact surface with the liquid crystal layer 216 can be employed. The liquid crystal layer 216 is disposed between the plurality of pixel electrodes 214 and the transparent conductive film 217, and the laser light L is modulated corresponding to an electric field formed by each of the pixel electrodes 214 and the transparent conductive film 217. That is, an electric field can be formed between the transparent conductive film 217 and the pixel electrode 2 1 4 by applying an active-matrix circuit or a voltage to the pixel electrode 214. The electric field is applied to the reflection film 2 15 and the liquid crystal layer 2 16 in a ratio corresponding to each thickness. Next, the arrangement direction of the liquid crystal molecules 2 1 6 a is changed corresponding to the magnitude of the electric field applied to the liquid crystal layer 2 16 . Once the light emission L of Ray-12-201105444 is incident on the liquid crystal layer 216 through the transparent substrate 218 and the transparent conductive film 217, the laser light L is modulated by the liquid crystal molecules 216a while passing through the liquid crystal layer 216, and is reflected in the reflective film 215. Then, it is removed by the liquid crystal layer 216 and then taken out. At this time, the control unit 250 (described later) applies a voltage ' to each of the pixel electrode portions 214a opposed to the transparent conductive film 217, and changes the liquid crystal layer 216 with the transparent conductive film 21 in response to the voltage. The refractive index of the portion held by each of the opposite pixel q electrode portions 214a (changes the refractive index of the liquid crystal layer 2 16 corresponding to each pixel position). By the change in the refractive index, the phase of the laser light L is changed in each pixel of the liquid crystal layer 2 16 corresponding to the applied voltage. In other words, the phase modulation corresponding to the hologram pattern can be given to each pixel by the liquid crystal layer 216 (that is, the modulation pattern as the hologram pattern imparted to the modulation is displayed in the spatial light modulation). 203). As a result, the wavefront of the laser light L incident on the reflective spatial light modulator 203 modulated and reflected can be adjusted in a specific direction perpendicular to the direction of progress of each of the light rays Q constituting the laser light L. At least one of the intensity, amplitude, phase, polarization, and the like of the laser light L may be adjusted by a deviation in the phase. Returning to Fig. 7, the 4f optical system 241 is for adjusting the wavefront shape of the laser light L modulated by the reflective spatial light modulator 203. The 4f optical system 241 has a first lens 24 la and a second lens 24lb. The lenses 241a and 24b are disposed between the reflective spatial light modulator 203 and the collecting optical system 204 as described below. In other words, in the lenses 241a and 241b, the distance between the reflective spatial light modulator 203 and the first lens 24la-13-201105444 is set as the focal length fl of the first lens 24la, and the collecting optical system 204 and the first The distance between the lens 241b is set to be the focal length f2 of the lens 24lb, the distance between the first lens 24la and the second lens 24lb is fl+f2, and the uticle lens 241a and the second lens 241b are disposed in the reflective spatial light modulator. 203 is coupled to the collecting optics 204 to form a two-sided telecentric optical system. The 4f optical system 241 can suppress the case where the laser light modulated by the reflective spatial light modulator 203 changes the shape of the wave surface due to spatial propagation and the aberration increases. In the 4f optical system 241 herein, the laser light L is adjusted so that the laser light L incident on the collecting optical system 204 becomes parallel light. The collecting optical system 208 is for concentrating the laser light L' modulated by the 4f optical system 24 1 inside the processed object 1. The collecting optical system 2〇4 is constituted by a plurality of lenses, and is provided on the bottom plate 233 of the body 231 via a driving unit 232 including a piezoelectric element or the like. Further, the laser processing apparatus 200 includes, in the living body 231, a surface observation unit 211 for observing the surface 3 of the object 1 and an AF (Auto Focus) for finely adjusting the distance between the collecting optical system 204 and the object to be processed. Unit 2 1 2 The surface observation unit 211 has a detector light source 211a that emits the visible light VL1 and a detector 2 1 1b that detects the reflected light VL2 of the visible light VL1 reflected on the surface 3 of the object 1 and detects it. In the surface observation unit 211, the visible light VL1 emitted from the observation light source 211a is reflected/transmitted by the mirror 208 and the beam splitters 2〇, 9, 210, and 238, and is collected by the collecting optical system 204 toward the object to be processed. Next, in the surface observation unit 211 -14-201105444, the reflected light VL2 reflected on the surface 3 of the object 1 is condensed by the collecting optical system 206 and transmitted/reflected by the beam splitters 238, 210, Light is received by the detector 2 lib through the beam splitter 209. The AF unit 212 emits the AF laser light LB1 and receives the reflected light LB2 of the AF laser light LB1 reflected on the surface 3 of the object 1 and detects it, thereby obtaining the surface along the line to cut 5 . 3 displacement data. Further, when the AF unit 212 is formed, the driving unit 232 is driven based on the obtained Q displacement data, and the condensing optical system 204 is bent along the surface 3 of the object 1 in the optical axis direction thereof. Move back and forth. Further, the laser processing apparatus 200 includes a control unit 250 for controlling the laser processing apparatus 200, and the control unit 250 is constituted by a CPU, a ROM, a RAM, and the like. The control unit 250 controls the laser light source 202 and adjusts the output or pulse amplitude of the laser light L emitted from the laser light source 02. Further, when the reforming field 7 is formed, the control unit 250 controls the position of the body 23 1 or the table 11 1 and the driving of the driving unit 232 so that the light collecting point p of the laser light L is processed from the object 1 The surface 3 is located at a specific distance and relatively moved along the line to cut 5 . Further, when the modified region 7 is formed, the control unit 250 applies a specific voltage to each of the electrode portions 214a and the transparent electrode film 217 of the pixel electrode 214 in the reflective spatial light modulator 203 to change the reflective spatial light tone. The refractive index of each element of the liquid crystal layer 2 16 in the transformer 2〇3, and a specific modulation pattern is displayed in the liquid crystal layer 2丨6. As a result, the aberration of the laser light L emitted from the reflective spatial light modulator 203 and condensed inside the object 1 can be controlled to be equal to or lower than a specific aberration (described later in detail). -15-201105444 When the object to be processed 1 is cut by using the laser processing apparatus 200 configured as described above, first, for example, an expanded tape is attached to the back surface of the object 1 and the processing is performed. Object! It is placed on the table 11 1 . Then, the condensed light is collected from the surface 3 of the object 1 in the inside of the 矽 wafer 1 1 and the laser light source 202 is irradiated with the laser light L (S 1 in Fig. 9). The emitted laser light L is horizontally reflected in the body 231, and is reflected downward by the mirror 205a, and the light intensity is adjusted by the attenuator 207. Then, the laser light L is reflected in the horizontal direction by the mirror 205b, and the intensity distribution is made uniform by the beam homogenizer 260 and incident on the reflective spatial light modulator 203. The laser light L that has entered the reflective spatial light modulator 203 is modulated by aberrations of a specific aberration or less, and the laser light L is collected inside the object 1 (S4). Specifically, the incident laser light L is transmitted through the modulation pattern represented by the liquid crystal layer 216 and is modulated corresponding to the modulation pattern, and is emitted obliquely upward in the horizontal direction. Then, the laser beam L is reflected upward by the mirror 2〇6a, and the polarization direction is changed to the direction along the line to cut 5 by the λ/2 wave plate 2M, and the mirror 2 0 6 b is horizontally Reflected and incident on the 4 f optical system 2 4 1 . The laser light L incident on the 4f optical system 24 1 is adjusted in shape to be incident on the collecting optical system 204 (S5) in parallel light. Specifically, the 'light beam L is converged by the first lens 241a, and is reflected downward by the mirror 219'. It is emitted by the confocal point 0, passes through the second lens 24b to be parallel light, and is then converged. -16 - 201105444 Thereafter, the laser beam L is incident on the collecting optical system 404 through the beam splitters 210 and 218, and is collected by the collecting optical system 204 on the object 1 placed on the stage 111. Internal (S6). Thereby, the modified region 7 is formed inside the object 1 along the cutting planned line 5. Then, the modified region 7 is used as the starting point of the cutting by the expansion and expansion belt, and the object 1 is cut along the line to cut 5 to separate the plurality of semiconductor wafers. Here, the laser processing apparatus 200 of the present embodiment is provided with a PSD (Q Position Sensitive Detector) 270a and 270b as a photosensor for detecting the position of the laser light L. The PSDs 270a and 270b described above are connected to the control unit 250, and the position information of the measured laser light L is output to the control unit 250. The PSD 270a is connected between the mirror 205a and the attenuator 207 in the optical path of the laser light L. Here, the PSD 270a is a laser beam L that is reflected by the mirror 205a, and is sequentially reflected by the mirrors 271 and 272 to guide the light to the PSD 270a. By this, the PSD 270a performs two-dimensional detection using the position of the center of gravity (center position) in the spot of the laser light L Q before the light intensity is adjusted by the attenuator 207 as a coordinate 値. The PSD 27 Ob is connected between the mirror 205b and the beam homogenizer 260 in the light path of the laser light L. Here, the PSD 270b is the laser light L to be reflected by the mirror 205b, and is sequentially reflected by the mirrors 273 and 274 to guide the light to the PSD 270b. Thereby, the PSD 270b performs two-dimensional detection by using the position of the center of gravity of the spot of the laser light L before the intensity uniformity of the beam homogenizer 260 is made uniform. Figure 10 is a diagram showing an example of the position information of the laser light measured by the PSD -17-201105444. In the figure, the coordinate 値Q of the measured laser light L is set by using a coordinate axis of the center of gravity of the laser light L in the initial state (in the initial adjustment) as the origin (reference position). As shown in Fig. 1, the coordinate 値 of the laser light L is detected based on the PSDs 270a and 270b, in other words, the positional change amount of the reference 値 (initial 値) with respect to the laser light L is detected. Therefore, in the present embodiment, the coordinates 値Q (S2) of the laser light L emitted from the laser light source 202 and incident on the reflective spatial light modulator 203 are constantly monitored by the PSDs 270a and 270b. Then, based on the coordinate 値Q of the laser light L input from at least one of the PSDs 270a and 270b, the control unit 250 controls the application of the electrode portion 214a and the transparent conductive film 217 of the reflective spatial light modulator 203. The voltage causes the position of the modulation pattern displayed on the liquid crystal layer 216 to be automatically changed (corrected) (S3). Specifically, the data table of the position change amount of the modulation pattern associated with the coordinate 値 of the laser light L is stored in advance in the control unit 250. As shown in FIG. 1, in the data table Tb herein, the coordinates of the laser light L are made such that the laser light L and the modulation pattern maintain a specific positional relationship (for example, the center of gravity of each other is matched). The positional change amount of Q and the modulation pattern is linked to each X and Y coordinate (refer to Fig. 8). Next, the data table Tb' is used to derive the position change amount of the modulation pattern from the coordinates 雷 of the laser light L measured by the PSDs 270a and 270b, so that the position of the modulation pattern changes only the position change amount. Alternatively, the position change amount of the modulation pattern can be calculated from the coordinate 値 of the laser light L by the following equation (1), so that the position of the modulation pattern is changed only by the bit -18-201105444. Δ X = PSDxxa △ Y = PSD yxb (1) where △ x : position change amount of the modulation pattern (X coordinate) △ Y : position change amount of the modulation pattern (Y coordinate) PSDx: coordinate 値 (X coordinate) of laser light L PSDy: coordinate 値 (Y coordinate) of laser light L Q a, b: specific setting, thereby making laser light L and display incident on liquid crystal layer 2 16 The positional relationship of the modulation pattern Η of the liquid crystal layer 216 is calibrated to a specific positional relationship with high precision of about 1 pixel. As a result, the reflection type spatial light modulator 203 can make the laser light L can be surely and accurately with the aberration of the laser light L condensed inside the object 1 being equal to or smaller than a specific aberration. Ground modulation 0 Figure 12 is a schematic diagram showing the relationship between the modulation pattern displayed on the liquid crystal layer and the laser light incident on the liquid Q layer. In Fig. 12, the liquid crystal layer 216 when viewed from the x-axis direction (see Fig. 8) is shown, and the modulation pattern Η is a circular shape. As shown in the first graph (a), for example, when the center of gravity of the displayed modulation pattern 与 and the center of gravity of the incident laser light L are different from each other and are not coincident, for example, the first 2 (b) As shown in the figure, the position of the modulation pattern Η is automatically moved according to the coordinate 値 of the laser light L, so that the center of gravity of the modulation pattern Η coincides with the center of gravity of the laser light L. As described above, in the present embodiment, the position of the modulation pattern Η in the reflective spatial light modulator 203 is changed in accordance with the position of the laser light L, and -19 - 201105444 makes the laser light L and the modulation pattern The relationship position of Η is calibrated with high precision of 1 pixel. Thereby, the reflective spatial light modulator 203 can be used to constantly and appropriately modulate the laser light L, and the aberration of the laser light L condensed on the object 1 can be stably suppressed. Therefore, according to the present embodiment, it is possible to stably form the modified field 7 with high precision in the object 1 to be processed. As a result, mechanical errors between the devices can be suppressed, and high processing quality can be maintained frequently. Fig. 13 is an enlarged photograph showing the state of the cut surface when the object to be processed is formed into a modified field and cut. Further, the pixel size of the reflective spatial light modulator 203 is 2 〇 β η χ 20 μπη, and the number of pixels is set to 792 x 600 in the horizontal (X) direction 792 and the vertical (Υ) direction 600. The figure shows a diagram in which the position of the aberration correction pattern 作为 as the modulation pattern is changed in the X direction in the liquid crystal layer 216. As can be seen from the example shown in Fig. 13, when the position change amount of the modulation pattern 〇 is 〇 (reference position) and +4 " m, the positional relationship between the laser light L and the modulation pattern Η becomes The positional relationship is specific and the quality of the cut surface is good. Further, it can be seen that when the position change amount of the modulation pattern Η is + 24 / / m, the quality of the cut surface is poor, and when the above is not the case, the quality of the cut surface is normal. Further, as can be seen from the example shown in Fig. 3, in the case where the modified region 7 having good precision is formed, high-precision calibration is important in the positional relationship between the laser light L and the modulation pattern Η. . Further, the amount of movement of 1 pixel or less (in other words, the amount of movement of the pixel size or less in the vertical and horizontal directions) can sufficiently exhibit the effect. In the case where the movement within the range of one pixel is not able to obtain good processing quality -20-201105444, it is necessary to adjust the setting of the optical system. The movement of the modulation pattern of 1 pixel or less will be described. Fig. 15 is a diagram for explaining the movement of a modulation pattern of 1 pixel or less. In Fig. 15, the refractive index corresponding to the modulation pattern (for example, aberration correction, etc.) in each pixel (liquid crystal) in the direction of the specific X direction is shown in a bar graph. In other words, the modulation pattern is represented by the refractive index of each of the plurality of pixels. Here, in order to explain, the two-dimensional pattern is simplified in a one-dimensional pattern. First, as shown in Fig. 15(a), a modulation pattern curve W1 indicating the refractive index of each pixel is set (in the case of Fig. 13, an aberration correction pattern curve). Moreover, 'the refractive index of each pixel is expressed by a modulation pattern curve' because in one dimension, but in the case of two-dimensional, the modulation pattern curve is a modulation indicating the refractive index of each pixel. Variable pattern. Then, as shown in Fig. 15(b), the modulation pattern curve w1 is moved to the right Q direction only by a specific amount of movement (as in the case of Fig. 13, for example, +4; /m). Next, the refractive index (circular mark in W2) corresponding to each pixel of the shifted modulation pattern curve W2 is calculated. Thereafter, the respective pixels are given a refractive index corresponding to the recalculated enthalpy. In the case of the example shown in Fig. 3, for example, the refractive index given to each pixel is set to 8 bits (256 degrees). The movement of the modulation pattern Η is performed as described above. Therefore, even if the movement is less than 1 pixel, the correction can be performed, and the modulation pattern (aberration correction pattern) can be moved more precisely. Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the PSDs 270a and 270b are provided as means for detecting the position of the laser light L, but only one of the above may be provided. In addition, other PSDs may be provided instead of PSD 270a, 270b or addition. For example, as shown in FIG. 14, it is also possible to connect between the beam splitter 23 8 and the collecting optics 2 〇 4 in the light path of the laser light l. pSD 370. In this case, the laser light L that has passed through the dichroic mirror 238 is reflected by the mirrors 371, 372 in sequence and guided to P S D 3 70. Therefore, it is possible to detect the position where the laser light L is concentrated before the processing object 1. Therefore, when the optical system of the laser light L is deviated or the like, it is necessary to detect the deviation of the position of the laser light L to change the position of the modulation pattern Η, and to form the positional relationship between the laser light L and the modulation pattern Η. correct. Further, in the above-described embodiment, the beam homogenizer 260 is provided, and the laser beam homogenizer 260 is used to cause the laser beam to be equalized, and the laser light is incident on the reflective spatial light modulator 203. Alternatively, the beam may be provided. The expander causes the laser light L that has been enlarged by the beam expander to be incident on the reflective spatial light modulator 203. In this case, in order to improve the position detection of the laser light L, it is preferable to detect the position of the laser light L before the beam path is enlarged by the beam expander by P SD . Further, the laser light incident surface when the modified region 7 is formed is not limited to the surface 3 of the object 1 and may be the back surface of the object 1. Further, in the above embodiment, it is of course possible to form a plurality of modified regions 7 along the line to cut 5 . -22-201105444 INDUSTRIAL APPLICABILITY According to the present invention, it is possible to stably form a field of modification with high precision on an object to be processed. BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] A schematic diagram of a laser processing apparatus for forming a modified field. Q [Fig. 2] is a plan view of the object to be processed in the field of reformation. [Fig. 3] A cross-sectional view of the ΠΙ-ΙΙΙ line of the object to be processed along the second drawing 第 [Fig. 4] A plan view of the object to be processed after laser processing. [Fig. 5] A cross-sectional view taken along line V-V of the object to be processed in Fig. 4. [Fig. 6] A cross-sectional view taken along line VI-VI of the object to be processed in Fig. 4. Fig. 7 is a schematic view showing the configuration of a laser processing apparatus according to an embodiment of the present invention. Q [Fig. 8] A partial cross-sectional view of a reflective spatial light modulator. [Fig. 9] A flow chart showing the sequence of the laser processing method. [Fig. 10] A schematic diagram showing an example of the positional information of the laser light measured by the PSD. [Fig. 1 1] A diagram showing a data table of the positional variation of the coordinate 値 and the modulation pattern of the laser light. [Fig. 12] A schematic view showing the relationship between the modulation pattern represented by the liquid crystal layer and the laser light incident on the liquid crystal layer. [Fig. I3] shows an enlarged photograph of the state of the cut surface when the object to be processed has been cut. -23- 201105444 [Fig. 14] A schematic view showing a configuration of another example of the laser processing apparatus of Fig. 7. [Fig. 15] A diagram for explaining the movement of a modulation pattern of 1 pixel or less [Description of main components] 1 : Object 7 : Field of modification 203 : Reflective spatial light modulator (space light tone Transformer) 216: Liquid crystal layer (display 7 Γ; part) Η : modulation pattern L: laser light Ρ: concentrating point-24-