201210732 六、發明說明： 【發明所屬之技術領域】 本發明係關於從板狀的加工對象物切出複數個有效部 之雷射加工方法。 【先前技術】 關於上述技術領域的雷射加工方法，藉由對晶圓照射 雷射光而沿著切斷預定線在晶圓內部形成改質區域，讓從 該改質區域產生的龜裂到達晶圓的表面及背面，藉此沿著 切斷預定線將晶圓切斷而取得複數個晶片的技術是已知的 (例如參照專利文獻1 )。 〔專利文獻1〕日本特開2004-343008號公報 【發明內容】 然而，基於讓從一片晶圓取出的晶片數增加的觀點， 相較於將對應於晶片之有效部對於晶圓配置成陣列狀，例 如沿列方向配置成鋸齒狀可能更有利。此外，也會有對於 晶圓設定複數個例如六角形等、四角形以外的有效部的情 況。在該等的情況’在鄰接的第1有效部及第2有效部可能 會發生’沿著第2有效部外緣之第2切斷預定線，朝向第1 有效部而碰上沿著第1有效部外緣之第1切斷預定線的狀態 。在此狀態下，當沿著第2切斷預定線形成改質區域時， 從該改質區域產生的龜裂可能到達第1有效部內，而有在 第1有效部發生損傷之虞。 -5- 201210732 於是，本發明目的是爲了提供一種雷射加工方法，在 沿著第2有效部外緣之第2切斷預定線朝向第1有效部而碰 上沿著第1有效部外緣之第1切斷預定線的情況，可防止第 1有效部發生損傷並沿著各切斷預定線形成改質區域。 本發明的一態樣之雷射加工方法，是從板狀的加工對 象物至少切出第1有效部及第2有效部之雷射加工方法，係 具備第1步驟和第2步驟；在該第1步驟，是沿著順沿第1有 效部的外緣之第1切斷預定線，讓雷射光的聚光點相對移 動’藉此沿著第1切斷預定線在加工對象物內部形成第i改 質區域；該第2步驟，是在第1步驟之後，沿著順沿第2有 效部的外緣且朝向第1有效部而碰上第1切斷預定線之第2 切斷預定線’讓雷射光的聚光點相對移動，藉此沿著第2 切斷預定線在加工對象物內部形成第2改質區域。 在該雷射加工方法，首先沿著第1切斷預定線形成第i 改質區域，之後沿著第2切斷預定線形成第2改質區域。因 此，縱使隨著第2改質區域的形成而從第2改質區域發生龜 裂’且該龜裂想要朝向第1有效部伸展，該龜裂之伸展能 藉由已經形成之第1改質區域以及從第1改質區域產生的龜 裂之至少一方予以擋止。因此，依據此雷射加工方法，在 沿著第2有效部外緣之第2切斷預定線朝向第1有效部而碰 上沿著第1有效部外緣之第1切斷預定線的情況，可防止第 1有效部發生損傷並沿著各切斷預定線形成改質區域。 在此，於第2步驟，可在第2切斷預定線當中離第1切 斷預定線既定距離部分以外的部分，形成第2改質區域。 -6- 201210732 如此，在第2切斷預定線當中離第1切斷預定線既定距離的 部分不致形成改質區域。因此，可防止隨著第2改質區域 的形成而在第1切斷預定線附近從第2改質區域發生龜裂， 能將從第2改質區域產生的龜裂朝向第1有效部的伸展予以 抑制。 此外，對於第1切斷預定線及第2切斷預定線分別以沿 加工對象物的厚度方向排列的方式形成複數列改質區域的 情況，只要至少將離加工對象物之雷射光入射面最近的改 質區域作爲第1改質區域及第2改質區域來形成即可。隨著 改質區域的形成之龜裂產生，相較於離雷射光入射面較遠 的改質區域，離雷射光入射面較近的改質區域更容易產生 。因此，只要至少將離雷射光入射面最近的改質區域作爲 上述第1改質區域及第2改質區域來形成，即可防止第1有 效部發生損傷。 此外，在第2步驟後，可進一步具備第3步驟，其是藉 由使從第1改質區域及第2改質區域產生的龜裂到達加工對 象物之表面及背面，而沿著第1切斷預定線及第2切斷預定 線將加工對象物切斷。如此，可從加工對象物精度良好地 切出第1有效部及第2有效部。 依據本發明，當沿著第2有效部外緣之第2切斷預定線 朝向第1有效部而碰上沿著第1有效部外緣之第1切斷預定 線的情況，可防止第1有效部發生損傷，並沿著各切斷預 定線形成改質區域。 201210732 【實施方式】 以下、針對本發明的較佳實施形態，參照圖式詳細地 說明。又在各圖中對於同一或相當的部分賦予同一符號而 省略重複的說明。 本發明的一實施形態之雷射加工方法，係藉由沿著切 斷預定線對加工對象物照射雷射光，以沿著切斷預定線在 加工對象物的內部形成改質區域。於是，首先針對該改質 區域的形成，參照第1圖〜第6圖做說明。 如第1圖所示，雷射加工裝置100係具備：將雷射光L 施以脈衝振盪之雷射光源101、配置成讓雷射光L的光軸（ 光路）方向改變90°之分光鏡103、以及用來將雷射光L聚 光之聚光用透鏡105。此外，雷射加工裝置100係具備用 來支承加工對象物1 (被經由聚光用透鏡105聚光後之雷射 光L所照射）之支承台107、讓支承台107移動之載台111、 爲了調節雷射光L的輸出、脈衝寬等而控制雷射光源1〇1之 雷射光源控制部1 02、以及控制載台1 1 1的移動之載台控制 部 115。 在該雷射加工裝置100，從雷射光源101射出的雷射光 L，經由分光鏡103將其光軸方向改變90°後，藉由聚光用 透鏡105聚光於支承台107上所載置之加工對象物1的內部 。在此同時，讓載台111移動，使加工對象物1相對於雷射 光L沿著切斷預定線5進行相對移動。藉此，讓沿著切斷預 定線5之改質區域形成於加工對象物1。 作爲加工對象物1，是使用半導體材料、壓電材料等 -8- 201210732 ，如第2圖所示，在加工對象物1上，設定有用來切斷加工 對象物1之切斷預定線5。切斷預定線5是呈直線狀延伸之 假想線。要在加工對象物1內部形成改質區域的情況，如 第3圖所示’是在聚光點p對準加工對象物1內部的狀態下 ’讓雷射光L·沿著切斷預定線5 (亦即第2圖的箭頭a方向） 相對地移動。藉此’如第4圖〜第6圖所示，讓改質區域7沿 著切斷預定線5形成於加工對象物1的內部，沿著切斷預定 線5形成之改質區域7成爲切斷起點區域8。 又聚光點P是雷射光L所聚光的部位。此外，切斷預定 線5 ’並不限於直線狀而是曲線狀亦可，並不限於假想線 而是在加工對象物1表面3上實際畫設的線亦可。此外，改 質區域7 ’可以是連續形成的情況，也可以是斷續形成的 情況。此外’改質區域7是列狀或點狀皆可，重點是改質 區域7至少形成於加工對象物1的內部即可。此外，會有以 改質區域7爲起點而形成龜裂的情況，龜裂及改質區域7是 露出加工對象物1的外表面（表面、背面、或外周面）亦 可。 附帶一提的’在此的雷射光L，是讓加工對象物1透過 且特別是在加工對象物1內部之聚光點附近被吸收，藉此 在加工對象物1形成改質區域7 (亦即內部吸收型雷射加工 )。如此，在加工對象物1的表面3幾乎不會吸收雷射光L ，因此加工對象物1的表面3不致發生熔融。一般而言，在 從表面3被熔融除去而形成孔洞、溝槽等除去部（表面吸 收型雷射加工）的情況，加工區域是從表面3側逐漸朝背 -9- 201210732 面側進展。 然而，本實施形態所形成的改質區域’是指密度、折 射率、機械強度、其他的物理特性變成與周圍不同的狀態 之區域。作爲改質區域，例如包括熔融處理區域、裂痕區 域、絕緣破壞區域、折射率變化區域等，也可以是其等混 合存在的區域。再者，作爲改質區域，也包括：加工對象 物的材料中改質區域的密度相較於非改質區域的密度發生 改變的區域、形成有晶格缺陷的區域（其等也能統稱爲高 密度差排區域）。 此外，熔融處理區域、折射率變化區域、改質區域的 密度相較於非改質區域的密度發生改變的區域、形成有晶 格缺陷的區域，進一步會有在該等區域的內部、或改質區 域和非改質區域的界面包含龜裂（裂縫、微裂痕）的情況 。所包含的龜裂’可能遍及改質區域的全面、僅形成於一 部分、或是形成於複數部分。作爲加工對象物1，例如包 括矽、玻璃、LiTa〇3或藍寶石（Al2〇3 )、或是由其等所 構成者。 此外’在本實施形態，藉由沿著切斷預定線5形成複 數個改質點（加工痕）’而形成改質區域7。改質點，是 藉由脈衝雷射光之1脈衝的照射（亦即1脈衝的雷射照射 :Laser Shot )所形成的改質部分’改質點的集合成爲改質 區域7。作爲改質點，是包含裂痕點、熔融處理點、折射 率Μ化點、或是混合存在有該等之至少一個等。 關於該改質點較佳爲’考慮所要求的切斷精度、所要 -10- 201210732 求的切斷面之平坦性、加工對象物的厚度、種類、結晶方 位等，來適當地控制其大小、所產生的龜裂長度。 接下來，針對本發明的一實施形態之雷射加工方法詳 細地說明。第7圖係本發明的一實施形態之雷射加工方法 對象之加工對象物的俯視圖。如第7圖所示，加工對象物1 係具備：矽晶圓1 1、以及包含複數個功能元件1 5且形成於 矽晶圓1 1上之功能元件層1 6。加工對象物1，是以功能元 件層16側的面爲表面3 ’以與功能元件層16相反側的面爲 背面4，是呈板狀的。功能元件1 5，例如包括：經由結晶 成長所形成之半導體動作層、光二極體等的受光元件、雷 射二極體等的發光元件、或是作爲電路而形成之電路元件 等。 功能元件1 5，是形成於每個長方形有效部1 8。各有效 部18，是對應於藉由切斷加工對象物1所取得的半導體晶 片。有效部18是配置成，使與矽晶圓11的定向平面6平行 的方向成爲長邊方向（亦即與定向平面6垂直的方向成爲 短邊方向）。再者，有效部18，在行方向（與定向平面6 平行的方向）是呈列狀配置’在列方向（與定向平面6垂 直的方向）則是呈鋸齒狀配置。藉此讓從一片矽晶圓Η取 出的半導體晶片數量增多。 如此，在列方向相鄰接之兩個有效部1 8 ’沿著其中一 方有效部18的短邊之切斷預定線52’會朝向另一方的有效 部18而碰上沿著另一方有效部18的長邊之切斷預定線51的 中間部分。又在加工對象物1的外緣部之無法配置有效部 -11 - 201210732 18的部分，是成爲非有效部19。 從以上的加工對象物1，如下述般切出複數個有效部 18。首先，在加工對象物1的背面4貼附擴展膠帶，將該加 工對象物1載置於雷射加工裝置1〇〇之支承台107上。而且 將載台1 1 1控制成，讓雷射光L的聚光點P位於離加工對象 物1表面3既定距離之內側。 接著，以加工對象物1的表面3爲雷射光入射面，沿著 切斷預定線5 1對加工對象物1照射雷射光L »亦即，沿著順 沿有效部18長邊之切斷預定線51，讓雷射光L的聚光點P相 對地進行移動（掃描）。在此，是控制載台1 1 1以進行雷 射光L的掃描》藉由此雷射光L的照射，如第8圖所示，沿 著切斷預定線5 1在加工對象物1的內部形成改質區域7 1。 沿著切斷預定線5 1形成改質區域7 1後，以加工對象物 1的表面3爲雷射光入射面，沿著切斷預定線52對加工對象 物1照射雷射光L。亦即，沿著順沿有效部1 8短邊之切斷預 定線52，讓雷射光L的聚光點P相對移動。藉由此雷射光L 的照射，如第9圖所示，沿著切斷預定線5 2在加工對象物1 的內部形成改質區域72。 這時，藉由將雷射光L的照射予以ΟΝ/OFF切換，在切 斷預定線52當中離切斷預定線51既定距離的端部分52a以 外的中間部分52b形成改質區域72。相當於該既定距離之 端部分52a的長度較佳爲，隨著改質區域72的形成（亦即 與改質區域72的形成大致同時），從改質區域72產生的龜 裂朝切斷預定線52方向伸展的距離之範圍，例如爲ΐΟμιη左 -12- 201210732 右。又對於沿著有效部18與非有效部19的邊界之切斷預定 線51，並不設置端部分52a (未形成改質區域72 )，而是 讓改質區域72與改質區域71交叉。 沿著切斷預定線52形成改質區域72之後，讓貼附於加 工對象物1的背面4之擴展膠帶擴展，使從改質區域71，72 產生的龜裂到達加工對象物1的表面3及背面4，藉此沿著 切斷預定線51，52將加工對象物1切斷。如此，如第1〇圖所 示，從加工對象物1切出複數個有效部18，而獲得具有功 能元件15之複數個半導體晶片25。 如以上所說明，當沿著一方的有效部18的短邊之切斷 預定線52，朝向另一方的有效部18而碰上沿著該另一方的 有效部1 8之長邊之切斷預定線5 1的中間部分的情況，首先 ，沿著順沿長邊之切斷預定線5 1形成改質區域7 1，之後， 沿著順沿短邊之切斷預定線52形成改質區域72。藉此，如 第1 1圖所示，隨著改質區域72的形成，從改質區域72產生 龜裂17，縱使該龜裂17想要朝向另一方的有效部18伸展， 該龜裂17之伸展會被已經形成的改質區域71、從改質區域 71產生的龜裂17所擋止。因此，可防止各有效部18發生損 傷，並能沿著各切斷預定線51，52形成改質區域71，72。 又此處的龜裂17，是隨著改質區域71，72的形成（即 使不讓任何的外力作用於加工對象物1 )，而從改質區域 71，72朝加工對象物1的厚度方向及切斷預定線51，52的方向 所產生的。 此外，如第1 1圖所示，沿著順沿短邊的切斷預定線52 -13- 201210732 形成改質區域72時，是在切斷預定線52的中間部分52b形 成改質區域72，但在切斷預定線52的端部分52a並不形成 改質區域72。藉此，隨著改質區域72的形成，在沿著長邊 之切斷預定線5 1附近從改質區域72產生龜裂1 7的現象能被 防止，而能抑制從改質區域72產生的龜裂17朝向另一方的 有效部18伸展》 此外，藉由使從改質區域71,72產生之龜裂17到達加 工對象物1的表面3及背面4，可沿著切斷預定線51，52將加 工對象物1切斷，因此可從加工對象物1精度良好地切出各 有效部18。這時，在位於有效部18與非有效部19的邊界之 有效部18的角部，由於改質區域71與改質區域72是形成交 叉，因此可防止在該有效部18的角部發生損傷。 第12圖係顯示，沿著切斷預定線51，52形成改質區域 71，72後，且讓貼附於加工對象物1的背面4之擴展膠帶擴 展前之加工對象物1的平面相片。如第12圖所示，在此情 況，隨著改質區域71，72的形成而從改質區域71，72產生之 龜裂1 7雖會到達加工對象物1的表面3，但沿著切斷預定線 5 2之龜裂1 7的伸展，會被沿著切斷預定線5 1之改質區域7 i 、龜裂17擋止。 第1 3圖係顯示，讓貼附於第1 2圖之加工對象物1的背 面4之擴展膠帶擴展後之加工對象物的平面相片。如第13 圖所示，可防止各有效部1 8發生損傷，而能從加工對象物 1精度良好地切出複數個半導體晶片25。第14圖係顯示半 導體晶片25的切斷面2 5 a之相片。如第14圖所示，在切斷 -14- 201210732 預定線52的中間部分52b形成有改質區域72 ’但在切斷預 定線5 2的端部分5 2 a並未形成改質區域7 2，可沿著切斷預 定線52將加工對象物1精度良好地切斷。又在第12圖’未 形成改質區域72之端部分52a的長度爲約ΙΟμιη。 以上雖是針對本發明的一實施形態做說明，但本發明 並不限定於上述實施形態。例如，對於各切斷預定線 51，52所形成之改質區域71，72的列數，並不限定於1列，亦 可爲複數列。其列數可對應於加工對象物1之厚度等而適 當地決定》 如第15圖所示，即使是對於各切斷預定線51，52，以 沿著加工對象物1的厚度方向排列的方式形成複數列改質 區域7 1，72的情況，只要先沿著順沿長邊之切斷預定線5 1 形成複數列的改質區域7 1，之後再沿著順沿短邊之切斷預 定線5 2形成複數列的改質區域7 2即可。而且在沿著順沿短 邊之切斷預定線52形成改質區域72時，只要在切斷預定線 52的中間部分52b形成改質區域72，且在切斷預定線52的 端部分52a不形成改質區域72即可。如此，可防止各有效 部18發生損傷’並能沿著各切斷預定線51，52形成改質區 域 71，72。 但是也會有以下的情況，亦即至少對於離加工對象物 1之雷射光入射面（在此爲表面3)最近之改質區域71，72 ’只要在形成改質區域71後再形成改質區域72，且在切斷 預定線5 2的端部分5 2 a不形成改質區域7 2，即可防止在各 有效部18發生損傷’並能沿著各切斷預定線51,5 2形成改 -15- 201210732 質區域71，72。這是因爲，隨著改質區域71，72的形成之龜 裂17產生，相較於離雷射光入射面較遠的改質區域71，72 ，離雷射光入射面較近的改質區域71，72更容易產生。此 作法在採用以下形成順序的情況是有效的。亦即，首先， 對於所有的切斷預定線51，52，形成離加工對象物1之雷射 光入射面最遠的改質區域71，72，之後，對於所有的切斷 預定線51，52，依序形成離加工對象物1之雷射光入射面之 每個距離的改質區域71，72。 此外，在上述實施形態，是藉由擴展膠帶之擴展而讓 外力作用於加工對象物1，使龜裂17到達加工對象物1的表 面3及背面4，但並不限定於此。對於各切斷預定線51，5 2 形成1列或複數列的改質區域7 1，72 (對於加工對象物1沒 有任何外力的作用），在此同時讓龜裂17到達加工對象物 1的表面3及背面4，藉此沿著切斷預定線51，52將加工對象 物1切斷亦可》 依據本發明’在沿著第2有效部外緣之第2切斷預定線 ’朝向第1有效部而碰上沿著第1有效部外緣之第1切斷預 定線的情況’可防止第1有效部發生損傷，並沿著各切斷 預定線形成改質區域。 【圖式簡單說明】 第1圖係形成改質區域所使用的雷射加工裝置之槪略 構造圖。 第2圖係作爲改質區域的形成對象之加工對象物的俯 -16- 201210732 視圖。 第3圖係沿著第2圖的加工對象物之III-III線之截面圖 〇 第4圖係雷射加工後的加工對象物之俯視圖。 第5圖係沿著第4圖的加工對象物之V-V線的截面圖。 第6圖係沿著第4圖的加工對象物之VI-VI線的截面圖 〇 第7圖係本發明的一實施形態之雷射加工方法對象之 加工對象物的俯視圖。 第8圖係實施本發明的一實施形態之雷射加工方法之 加工對象物的局部截面圖。 第9圖係實施本發明的一實施形態之雷射加工方法之 加工對象物的局部截面圖。 第1 0圖係實施本發明的一實施形態之雷射加工方法之 加工對象物的俯視圖。 第1 1圖係實施本發明的一實施形態之雷射加工方法後 之加工對象物的槪念圖。 第12圖係顯示形成有龜裂之加工對象物的平面相片。 第13圖係顯示切斷後的加工對象物之平面相片。 第14圖係顯示切斷後的加工對象物之切斷面的相片。 第1 5圖係實施本發明的其他實施形態之雷射加工方法 後的加工對象物之槪念圖。 【主要元件符號說明】 -17- 201210732 1 :加工對象物 3 :表面 4 :背面 17 :龜裂 1 8 :有效部 5 1，5 2 :切斷預定線 5 2 a :端部分 5 2 b :中間部分 7 1,7 2 :改質區域 L :雷射光 P :聚光點[Technical Field] The present invention relates to a laser processing method in which a plurality of effective portions are cut out from a plate-shaped object to be processed. [Prior Art] In the laser processing method of the above technical field, a modified region is formed inside the wafer along the line to cut by irradiating the wafer with laser light, and the crack generated from the modified region reaches the crystal A technique for cutting a wafer along a line to cut to obtain a plurality of wafers along the line to be cut is known (for example, see Patent Document 1). [Patent Document 1] Japanese Laid-Open Patent Publication No. 2004-343008. SUMMARY OF THE INVENTION However, based on the increase in the number of wafers taken out from one wafer, the wafers are arranged in an array as compared with the effective portions corresponding to the wafers. For example, it may be more advantageous to arrange it in a zigzag shape along the column direction. Further, a plurality of effective portions other than a quadrangle such as a hexagon or the like may be set for the wafer. In these cases, 'the second effective cutting portion along the outer edge of the second effective portion may occur in the adjacent first effective portion and the second effective portion, and the first effective portion may be struck along the first The state of the first cutting planned line of the outer edge of the effective portion. In this state, when the modified region is formed along the second planned cutting line, the crack generated from the modified region may reach the first effective portion, and the first effective portion may be damaged. -5-201210732 Accordingly, an object of the present invention is to provide a laser processing method in which a second cutting line along the outer edge of the second effective portion faces the first effective portion and collides along the outer edge of the first effective portion. In the case of the first planned cutting line, it is possible to prevent the first effective portion from being damaged and to form a modified region along each of the planned cutting lines. A laser processing method according to an aspect of the present invention is directed to a laser processing method in which at least a first effective portion and a second effective portion are cut out from a plate-shaped object to be processed, and the first step and the second step are provided; In the first step, the first cutting line along the outer edge of the first effective portion is moved along the first cutting line, and the condensing point of the laser light is relatively moved, thereby forming the inside of the object along the first cutting line. The i-th modification region; the second step is a second cutting schedule that hits the first cutting planned line along the outer edge of the second effective portion and faces the first effective portion after the first step The line 'relatively moves the condensed spot of the laser light, thereby forming a second modified region inside the object to be processed along the second line to cut. In the laser processing method, first, the i-th modified region is formed along the first line to cut, and then the second modified region is formed along the second line to cut. Therefore, even if the crack occurs from the second modified region as the second modified region is formed and the crack is intended to extend toward the first effective portion, the crack can be stretched by the first modification that has been formed. At least one of the quality region and the crack generated from the first modified region is blocked. Therefore, according to the laser processing method, when the second cutting planned line along the outer edge of the second effective portion faces the first effective portion and hits the first cutting planned line along the outer edge of the first effective portion, It is possible to prevent the first effective portion from being damaged and to form a modified region along each of the planned cutting lines. Here, in the second step, the second modified region can be formed in a portion other than the predetermined distance portion of the first cutting planned line among the second cutting planned lines. -6-201210732 As described above, the modified region is not formed in the portion of the second cutting planned line that is a predetermined distance from the first cutting planned line. Therefore, it is possible to prevent the second modified region from being cracked in the vicinity of the first cutting planned line in the vicinity of the first modified region, and it is possible to prevent the crack generated from the second modified region from being directed to the first effective portion. Stretching is suppressed. In addition, when the first line to be cut and the second line to be cut are respectively arranged in a plurality of rows of modified regions so as to be aligned in the thickness direction of the object to be processed, at least the laser light incident surface of the object to be processed is at least The modified region may be formed as the first modified region and the second modified region. With the formation of cracks in the modified region, the modified region closer to the incident surface of the laser light is more likely to be generated than the modified region farther from the incident surface of the laser light. Therefore, it is possible to prevent the first effective portion from being damaged by forming at least the modified region closest to the incident surface of the laser light as the first modified region and the second modified region. Further, after the second step, a third step may be further provided, in which the crack generated from the first modified region and the second modified region reaches the front surface and the back surface of the object to be processed, and is along the first step. The cutting target line and the second cutting planned line cut the object to be processed. In this way, the first effective portion and the second effective portion can be accurately cut out from the object to be processed. According to the present invention, when the second cutting planned line along the outer edge of the second effective portion faces the first effective portion and hits the first cutting planned line along the outer edge of the first effective portion, the first prevention can be prevented. The effective portion is damaged, and a modified region is formed along each planned cutting line. [Embodiment] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the respective drawings, the same or corresponding components are designated by the same reference numerals, and the description thereof will not be repeated. In the laser processing method according to the embodiment of the present invention, the object to be processed is irradiated with the laser beam along the line to cut, and the modified region is formed inside the object to be processed along the line to cut. Therefore, first, the formation of the modified region 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 applies pulsed laser light to the laser beam 101, and a spectroscope 103 that is arranged to change the optical axis (optical path) direction of the laser beam L by 90°. And a collecting lens 105 for collecting the laser light L. Further, the laser processing apparatus 100 is provided with a support base 107 for supporting the object 1 to be irradiated (the laser beam L is condensed by the condensing lens 105), and a stage 111 for moving the support table 107, A laser light source control unit 102 that controls the output of the laser light L, a pulse width, and the like to control the laser light source 1〇1, and a stage control unit 115 that controls the movement of the stage 1 1 1 . In the laser processing apparatus 100, the laser beam L emitted from the laser light source 101 is changed in the optical axis direction by the beam splitter 103 by 90 degrees, and then condensed on the support table 107 by the collecting lens 105. The inside of the object 1 to be processed. At the same time, the stage 111 is moved to relatively move the object 1 with respect to the laser beam L along the line to cut 5 . Thereby, the modified region along the cutting predetermined line 5 is formed in the object 1 to be processed. As the object to be processed 1, a semiconductor material, a piezoelectric material, or the like is used. -8 - 201210732. As shown in Fig. 2, a cutting line 5 for cutting the object 1 is set on the object 1 to be processed. The line to cut 5 is an imaginary line extending linearly. In the case where the modified region is formed inside the object 1 as shown in Fig. 3, 'the state where the spotlight p is aligned with the inside of the object 1 is 'to let the laser light L· along the line to cut 5 (that is, the direction of the arrow a in Fig. 2) moves relatively. As a result, as shown in FIG. 4 to FIG. 6, the modified region 7 is formed inside the object 1 along the line to cut 5, and the modified region 7 formed along the line to cut 5 is cut. Break starting point area 8. Further, the condensed spot P is a portion where the laser light L is condensed. Further, the cutting planned line 5' is not limited to a linear shape but may be curved, and may not be limited to an imaginary line but may be a line actually drawn on the surface 3 of the object 1 to be processed. Further, the modified region 7' may be formed continuously or intermittently. Further, the modified region 7 may be in the form of a column or a dot, and it is important that the modified region 7 is formed at least inside the object 1 to be processed. Further, a crack may be formed from the modified region 7 as a starting point, and the cracked and modified region 7 may expose the outer surface (surface, back surface, or outer peripheral surface) of the object 1 to be processed. Incidentally, the laser light L here is such that the object 1 is transmitted and is absorbed particularly in the vicinity of the condensing point inside the object 1 to form the modified region 7 in the object 1 (also That is, internal absorption type laser processing). As described above, 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 removal portion such as a hole or a groove (surface absorption type laser processing), the processing region gradually progresses from the surface 3 side toward the back side -9-201210732. However, the modified region ′ formed in the present embodiment means a region in which the density, the refractive index, the mechanical strength, and other physical properties are different from the surroundings. The modified region may include, for example, a molten processed region, a cracked region, an insulating fracture region, a refractive index change region, or the like, or a region in which the mixture is mixed. Further, the modified region includes: a region in which the density of the modified region in the material of the object to be processed is changed from that in the non-modified region, and a region in which a lattice defect is formed (these can also be collectively referred to as High density difference row area). Further, the region where the density of the molten processed region, the refractive index change region, and the modified region is changed compared to the density of the non-modified region, and the region where the lattice defect is formed may further be internal to the regions, or may be modified. The interface between the qualitative region and the non-modified region includes cracks (cracks, micro-cracks). The included cracks may be comprehensive throughout the modified region, formed only in one portion, or formed in a plurality of portions. The object to be processed 1 includes, for example, enamel, glass, LiTa〇3, or sapphire (Al2〇3), or the like. Further, in the present embodiment, the modified region 7 is formed by forming a plurality of modified spots (machining marks) along the line to cut 5 . The modified spot is a modified portion formed by the irradiation of one pulse of the pulsed laser light (i.e., one shot of laser shot: Laser Shot). The modified point includes at least one of a crack point, a molten processing point, a refractive index deuteration point, or a mixture. It is preferable to appropriately control the size and the size of the cut surface in consideration of the required cutting accuracy, the flatness of the cut surface to be obtained in -10-201210732, the thickness, type, and crystal orientation of the object to be processed. The length of the crack produced. Next, a laser processing method according to an embodiment of the present invention will be described in detail. Fig. 7 is a plan view showing a target object to be processed by a laser processing method according to an embodiment of the present invention. As shown in Fig. 7, the object 1 includes a ruthenium wafer 1 1 and a functional element layer 16 including a plurality of functional elements 15 and formed on the ruthenium wafer 1 . The object 1 is formed such that the surface on the side of the functional element layer 16 is the surface 3' and the surface on the opposite side to the functional element layer 16 is the back surface 4, and is formed in a plate shape. The functional element 15 includes, for example, a semiconductor operation layer formed by crystal growth, a light-receiving element such as a photodiode, a light-emitting element such as a laser diode, or a circuit element formed as a circuit. The functional element 15 is formed in each rectangular effective portion 18. Each of the effective portions 18 corresponds to a semiconductor wafer obtained by cutting the object 1 to be processed. The effective portion 18 is disposed such that the direction parallel to the orientation flat surface of the 矽 wafer 11 becomes the longitudinal direction (i.e., the direction perpendicular to the orientation plane 6 becomes the short side direction). Further, the effective portion 18 is arranged in a row in the row direction (direction parallel to the orientation flat surface 6) and is arranged in a zigzag manner in the column direction (direction perpendicular to the orientation flat surface 6). This increases the number of semiconductor wafers taken from a wafer. In this way, the two cutting lines 52' along the short sides of one of the effective portions 18 in the column direction are directed toward the other effective portion 18 and are along the other effective portion. The long side of 18 cuts off the middle portion of the predetermined line 51. Further, in the outer edge portion of the object 1 to be processed, the portion where the effective portion -11 - 201210732 18 cannot be disposed is the ineffective portion 19. From the above object 1 to be processed, a plurality of effective portions 18 are cut out as follows. First, an expansion tape is attached to the back surface 4 of the object 1 to be placed, and the object 1 to be processed is placed on the support table 107 of the laser processing apparatus 1A. Further, the stage 1 1 1 is controlled such that the condensed spot P of the laser light L is located inside a predetermined distance from the surface 3 of the object 1 to be processed. Next, the surface 3 of the object 1 is a laser light incident surface, and the object 1 is irradiated with laser light L along the line to cut 5 1 , that is, the cutting along the long side of the effective portion 18 is predetermined. The line 51 moves (scans) the focused spot P of the laser light L relatively. Here, the control of the stage 1 1 1 to perform the scanning of the laser light L is performed by the laser beam L, and as shown in FIG. 8, the inside of the object 1 is formed along the line to cut 5 1 . Modified area 7 1. After the modified region 7 1 is formed along the line to cut 5 1 , the surface 3 of the object 1 is a laser light incident surface, and the object 1 is irradiated with the laser light L along the line to cut 52 . That is, the condensing point P of the laser light L is relatively moved along the cutting predetermined line 52 along the short side of the effective portion 18. By the irradiation of the laser light L, as shown in FIG. 9, the modified region 72 is formed inside the object 1 along the line to cut 521. At this time, by the ON/OFF switching of the irradiation of the laser light L, the modified region 72 is formed in the intermediate portion 52b other than the end portion 52a which is a predetermined distance from the planned cutting line 51 among the cut-off lines 52. The length of the end portion 52a corresponding to the predetermined distance is preferably such that, as the modified region 72 is formed (i.e., substantially simultaneously with the formation of the modified region 72), the crack generated from the modified region 72 is cut toward the cut. The range of the distance in which the line 52 extends is, for example, ΐΟμιη left-12-201210732 right. Further, with respect to the cutting planned line 51 along the boundary between the effective portion 18 and the ineffective portion 19, the end portion 52a is not provided (the modified region 72 is not formed), but the modified region 72 is caused to intersect the modified region 71. After the modified region 72 is formed along the line to cut 52, the expansion tape attached to the back surface 4 of the object 1 is expanded, and the crack generated from the modified regions 71 and 72 reaches the surface 3 of the object 1 The back surface 4 is used to cut the object 1 along the line to cut 51, 52. As described above, as shown in Fig. 1, a plurality of effective portions 18 are cut out from the object 1 to obtain a plurality of semiconductor wafers 25 having the functional elements 15. As described above, when the predetermined line 52 is cut along the short side of one of the effective portions 18, the cutting of the long side of the other effective portion 18 is struck toward the other effective portion 18. In the case of the intermediate portion of the line 51, first, the modified region 7 is formed along the line to cut 5 1 along the long side of the straight edge, and then the modified region 72 is formed along the line to cut 52 along the short side of the straight edge. . As a result, as shown in Fig. 1, as the modified region 72 is formed, the crack 17 is generated from the modified region 72, and the crack 17 is intended to extend toward the other effective portion 18, and the crack 17 is formed. The extension is blocked by the already formed modified region 71 and the crack 17 generated from the modified region 71. Therefore, it is possible to prevent the respective effective portions 18 from being damaged, and to form the modified regions 71, 72 along the respective planned cutting lines 51, 52. Further, the crack 17 here is formed in the thickness direction of the object 1 from the modified regions 71 and 72 along with the formation of the modified regions 71 and 72 (even if no external force is applied to the object 1). And the direction in which the predetermined lines 51, 52 are cut. Further, as shown in Fig. 1, when the modified region 72 is formed along the cutting line 52 - 13 - 201210732 along the short side, the modified region 72 is formed in the intermediate portion 52b of the cutting planned line 52, However, the modified region 72 is not formed at the end portion 52a of the cut line 52. Thereby, with the formation of the modified region 72, the phenomenon that the crack 17 is generated from the modified region 72 in the vicinity of the planned line 5 1 along the long side can be prevented, and generation from the modified region 72 can be suppressed. The crack 17 is extended toward the other effective portion 18. Further, by causing the crack 17 generated from the modified regions 71, 72 to reach the surface 3 and the back surface 4 of the object 1, it is possible to follow the line to cut 51. Since the object 1 is cut by the object 52, the effective portions 18 can be accurately cut out from the object 1 to be processed. At this time, since the modified region 71 and the modified region 72 are formed at the corner portion of the effective portion 18 located at the boundary between the effective portion 18 and the ineffective portion 19, damage at the corner portion of the effective portion 18 can be prevented. Fig. 12 is a plan view showing the object 1 to be processed before the expanded tapes attached to the back surface 4 of the object 1 are formed along the line to cut 51, 52. As shown in Fig. 12, in this case, the cracks 17 generated from the modified regions 71, 72 with the formation of the modified regions 71, 72 reach the surface 3 of the object 1, but are cut along the surface. The extension of the crack 17 of the predetermined line 5 2 is blocked by the modified region 7 i and the crack 17 along the line to cut 5 1 . Fig. 13 shows a plan view of the object to be processed after the expansion tape of the back surface 4 of the object 1 to be processed in Fig. 2 is expanded. As shown in Fig. 13, it is possible to prevent the respective effective portions 18 from being damaged, and it is possible to cut out a plurality of semiconductor wafers 25 accurately from the object 1 to be processed. Fig. 14 is a photograph showing the cut surface 2 5 a of the semiconductor wafer 25. As shown in Fig. 14, the modified portion 72' is formed in the intermediate portion 52b of the cut line -14 - 201210732 predetermined line 52, but the modified portion 7 2 is not formed at the end portion 5 2 a of the cut line 5 2 The object 1 to be processed can be cut accurately along the line to cut 52. Further, in Fig. 12, the length of the end portion 52a where the modified region 72 is not formed is about ΙΟμιη. Although the above is an embodiment of the present invention, the present invention is not limited to the above embodiment. For example, the number of columns of the modified regions 71, 72 formed by the respective cutting planned lines 51, 52 is not limited to one column, and may be plural columns. The number of rows can be appropriately determined in accordance with the thickness of the object 1 and the like. As shown in Fig. 15, even the respective planned cutting lines 51 and 52 are arranged in the thickness direction of the object 1 to be processed. In the case where the plurality of column modified regions 71, 72 are formed, it is only necessary to form the modified region 7 1 of the plurality of columns along the planned cutting line 5 1 along the long side of the straight edge, and then cut along the short side of the straight edge. Line 5 2 may form a modified region 7 2 of a plurality of columns. Further, when the modified region 72 is formed along the cut line 52 along the short side, the modified region 72 is formed at the intermediate portion 52b of the cut line 52, and the end portion 52a of the cut line 52 is not It is sufficient to form the modified region 72. Thus, damage to each of the effective portions 18 can be prevented and the modified regions 71, 72 can be formed along the respective cut lines 51, 52. However, there is also a case where at least the modified region 71, 72' closest to the laser light incident surface (here, the surface 3) of the object 1 is reformed as long as the modified region 71 is formed. In the region 72, and the end portion 5 2 a of the cut-off line 5 2 does not form the modified region 7 2, damage can be prevented from occurring in each of the effective portions 18 and can be formed along the respective cut lines 51, 52. Change -15- 201210732 quality area 71,72. This is because, as the crack 17 formed by the modified regions 71, 72 is generated, the modified region 71 closer to the incident surface of the laser light is compared with the modified region 71, 72 which is farther from the incident surface of the laser light. , 72 is easier to produce. This is effective in the case where the following formation order is employed. In other words, first, the modified regions 71, 72 which are farthest from the incident light incident surface of the object 1 are formed for all the planned cutting lines 51, 52, and then, for all the cut lines 51, 52, The modified regions 71, 72 are formed in sequence from each of the laser light incident faces of the object 1 to be processed. Further, in the above-described embodiment, the external force is applied to the object 1 by the expansion of the expansion tape, and the crack 17 reaches the surface 3 and the back surface 4 of the object 1, but the invention is not limited thereto. Each of the cutting planned lines 51, 5 2 forms one or more modified regions VII, 72 (there is no external force acting on the object 1), and at the same time, the crack 17 reaches the object 1 The surface 3 and the back surface 4 are used to cut the object 1 along the line to cut 51, 52. According to the present invention, the second line is cut along the second line along the outer edge of the second effective portion. When the effective portion hits the first cutting planned line along the outer edge of the first effective portion, the first effective portion can be prevented from being damaged, and the modified region can be formed along each planned cutting line. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic structural view of a laser processing apparatus used for forming a modified region. Fig. 2 is a view of the object to be processed which is the object of formation of the modified region. Fig. 3 is a cross-sectional view taken along line III-III of the object to be processed in Fig. 2 〇 Fig. 4 is a plan view of the object to be processed after laser processing. Fig. 5 is a cross-sectional view taken along line V-V of the object of Fig. 4; Fig. 6 is a cross-sectional view taken along line VI-VI of the object of Fig. 4, and Fig. 7 is a plan view of the object to be processed by the laser processing method according to the embodiment of the present invention. Fig. 8 is a partial cross-sectional view showing the object to be processed which is subjected to the laser processing method according to the embodiment of the present invention. Fig. 9 is a partial cross-sectional view showing an object to be processed which is subjected to a laser processing method according to an embodiment of the present invention. Fig. 10 is a plan view showing an object to be processed which is subjected to a laser processing method according to an embodiment of the present invention. Fig. 1 is a view showing the object to be processed after the laser processing method according to the embodiment of the present invention is carried out. Fig. 12 is a plan view showing a processed object on which cracks are formed. Fig. 13 is a plan view showing the object to be processed after cutting. Fig. 14 is a photograph showing the cut surface of the object to be processed after cutting. Fig. 15 is a conceptual view of the object to be processed after the laser processing method according to another embodiment of the present invention is carried out. [Description of main component symbols] -17- 201210732 1 : Object to be processed 3 : Surface 4 : Back surface 17 : Crack 1 8 : Effective portion 5 1,5 2 : Cut-off line 5 2 a : End portion 5 2 b : Middle part 7 1,7 2 : modified area L: laser light P: concentrated spot