200539978 馨 爾 九、發明說明： 【發明所屬之技術領域】 本發明係有關於沿著預定切斷線將晶圓狀之加工對象 物進行切斷之加工對象物切斷方法。 【先前技術】 在先前的此類型技術中，以下所述專利文獻/日本專利特 開2004- 1 076號公報中記載有如下之雷射加工方法。也就 是說，在平板狀之加工對象上裝設保護其表面之元件，利 用把加工對象物之背面作爲雷射光射入面而將雷射光加以 照射之方式，形成沿著預定切斷線在加工對象物內部藉由 重整領域來形成切斷起點領域。接著，在加工對象物其背 面裝設具有延展性的薄膜，並使該延展性的薄膜進行延展 之方式’將切斷起點領域作爲起點來切斷加工對象物使所 產生之多複數個部分互相分離。 專利文獻1 :日本專利物開2004- 1 076號公報。 【發明內容】 〔發明揭示〕 〔發明所欲解決之問題〕 但是，在前述之雷射加工方法中，形成有切斷起點領域 之加工對象物係將切斷起點領域作爲起點而容易被切斷之 狀態，而且將切斷起點領域作爲起點來切斷加工對象物之 情況下藉此使產生之複數個部分會處於互相緊密連接之狀 態。因此，例如，在作爲保護表面元件而採用保護薄膜之 情況下，爲了防止被切斷所產生之複數個部分發生碎屑和 破裂等之不合適的現象，必須要慎重地處理形成切斷起點 200539978 領域之加工對象物。 因此，本發明係有鑒於前述情況加以提出，以提拱使形 成有切斷起點領域之加工對象物的處理容易化、並且可防 止把切斷起點領域作爲起點而加工對象物受到切斷後所產 生之複數個部分處所產生之碎屑和裂化等之不合適之加工 對象物切斷方法爲目的。 (解決問題之手段） 爲了達成上述目的，有關本發明之一種加工對象物切斷 方法，係沿著預定切斷線將晶圓狀加工對象物切斷之加工 對象物切斷方法，其特徵爲包含有在加工對象物之表面上 安裝有形狀維持體之狀態下，將加工對象物之背面作爲雷 射光射入面而將聚光點聚合在加工對象物內部進而以雷射 光照射來形成重整領域，根據該重整領域，沿著預定切斷 線從雷射光射入面在預定距離內側來形成切斷起點領域之 製程；及在形成前述切斷起點領域之加工對象物的背面上 代安裝可擴張薄膜之製程；及由安裝可擴張薄膜之加工對 象物的表面來卸下形狀維持體之製程；及使可擴張薄膜進 行擴張，將切斷起點領域作爲起點而使加工對象物被切斷 所產生之複數個部分互相分離之製程。 在該加工對象物切斷方法中，將加工對象物之背面作爲 雷射光射入面而沿著預定切斷線在加工對象物之內部藉由 重整領域來形成切斷起點領域時起，直到加工對象物之背 面上安裝可擴張薄膜爲止，在加工對象物之表面上安裝有 形狀維持體。藉由該形狀維持體，由於能夠確實地防止加 工對象物之變形，所以能夠將形成切斷起點領域之加工對 200539978 象物的處理變得容易化。然後，藉由從加工對象物之表面 卸下形狀維持體，可使擴張薄膜加以擴張，將切斷起點領 域作爲起點來切斷使所產生之複數個部分互相分離。藉 此，形成有切斷起點領域之加工對象物，由於歷經了其變 形確實受到防止之狀態而被切斷成複數個部分，所以能夠 防止受到切斷所產生之複數個部分產生碎屑和破裂等之不 合適現象。在此，所謂的切斷起點領域，係指加工對象物 受到切斷時成爲切斷起點之領域。該切斷起點領域，係存 | 有因重整領域被連續地形成而形成之情況，也存有重整領 域斷續性地被形成而形成之情況。又，重整領域，係在加 工對象物內部使聚光點聚合一起來照射雷射光之方式，藉 由多光子吸收或是與其同等之光吸收在加工對象物內部產 生所形成。 又，來形成切斷起點領域之製程，係在雷射加工裝置中 進行，卸下形狀維持體之製程以及使複數個部分互相分離 之製程，係在薄膜擴張裝置中進行爲佳。藉由使用這種雷 Φ 射加工裝置和薄膜擴張裝置，能夠將各裝置之構成簡易 化。然後，從雷射加工裝置朝薄膜擴張裝置之加工對象物 之搬運上，雖然在加工對象物內部形成切斷起點領域，但 是由於在加工對象物表面上安裝有形狀維持體，所以能夠 防止在搬運中將切斷起點領域作爲起點而加工對象物意外 地受到切斷之情況。 又，在加工對象物其表面上形成有功能元件之半導體基 板之情況下，由於在半導體基板之表面上安裝有形狀維持 體，所以能夠來保護功能元件。進而，例如即使功能元件 200539978 讎 1 上存有反射雷射光的部分，但在形成切斷起點領域製程中 其背面會成爲雷射光射入面，所以能夠在半導體基板內部 確實地形成切斷起點領域。因此，所謂的功能元件，例如， 藉由結晶成長所形成之半導體動作層，光電二極體等之感 光元件、雷射二極體等之發光元件、作爲電路所形成之電 路元件等。 又，在形成切斷起點領域之製程之前，在加工對象物的 表面上安裝有形狀維持體之狀態下，可包含有來硏磨加工 φ 對象物其背面之製程，或是，亦可以在形成切斷起點領域 之製程以及安裝可擴張薄膜之製程之間，包含在加工對象 物的表面上安裝形狀維持體之狀態下，來硏磨加工對象物 其背面之製程。藉此，能夠保護加工對象物的表面，同時 可防止加工對象物的變形，將加工對象物進行薄型化。此 等是，爲了隨著半導體裝置的小型化而期待半導體基板之 薄型化，所以加工對象物爲半導體基板情況下極爲有效。 因此，所謂的硏磨，係指含有切削、硏削、化學蝕刻等之 思味 另外，形狀維持體，係玻璃製或者樹脂製，介於黏合劑 層能安裝於加工對象物的表面上，在卸下形狀維持體之製 程中，從形狀維持體側在黏合劑層來照射電磁波之方式， 或者來加熱黏合劑層之方式使黏合劑層之黏合力下降，由 加工對象物的表面來卸下形狀維持體爲佳。藉此，對於加 * 工對象物其表面的形狀維持體之安裝、卸下能夠容易地進 * 行。 (發明之效果） 200539978 1 若依據本發明，則能夠將形成切斷起點領域之加工對象 物的處理容易化，並且能夠防止將切斷起點領域作爲起點 而加工對象物受到切斷所產生之複數個部分產生碎屑和破 裂等之不合適現象。 【實施方式】 以下、將針對適合本發明之加工對象物切斷方法之實施 形態，參照圖面詳細地加以說明。在本實施形態中，由於 在加工對象物內部形成重整領域而利用稱爲多光子吸收之 現象。因此，在一開始，針對藉由多光子吸收而形成重整 領域之雷射加工方法加以說明。 光子的能量h >比材料其吸收之頻帶間隙EG更小時會 光學性地成爲透明。因此，材料產生吸收的條件是 h v >EG。但是，即使是光學地透明，當雷射光的強度變得非常 大時，在nh p >EG (n = 2，3，4，…）之條件下材料產生吸收。 此現象稱爲多光子吸收。在脈衝波之情況下，雷射光的強 度係以雷射光之聚光點之峰値功率密度（W/cm 2)來決定、例 如，當峰値功率密度爲lxl 08( W / c m 2)以上之條件下會產 生多光子吸收。峰値功率密度是由（在聚光點之雷射光之每 一單位脈波的能量）+ (雷射光之光線照射點截面積X脈衝波 寬度）來求出。另外，在連續波之情況下，雷射光之強度係 以雷射光之聚光點之電場強度（W/cm2)來決定。 針對前述利用多光子吸收之本實施形態之雷射加工方 法之原理，參照第1圖〜第6圖加以說明。如第1圖所示， 在晶圓狀（平板狀）之加工對象物1之表面3上，存在有切 斷加工對象物1用之預定切斷線5。預定切斷線5係呈直線 200539978 狀延長之假想線。在本實施形態之雷射加工方法中’如第 2圖所示，在產生多光子吸收之條件下將聚光點P聚合在 一起而對加工對象物1內部照射雷射光L形成重整領域 7。此外，聚光點P係雷射光L聚光之處。另外，預定切斷 線5不拘限於直線狀亦可以是曲線狀，也可以不拘限於是 假想線，亦可在實際上加工對象物1上所牽引之線。 然後，藉由使雷射光L沿著預定切斷線5 (即第1圖之 箭頭A方向）作相對地移動之方式，令聚光點P沿著預定切 斷線5移動。藉此，如第3圖〜第5圖所示，重整領域7沿 著預定切斷線5行程在加工對象物1之內部，該重整領域 7會成爲切斷起點領域8。本實施形態之雷射加工方法，並 非是藉由加工對象物1吸收雷射光L之方式令加工對象物 1發熱而形成重整領域7。而是使雷射光L透射過加工對象 物1而使加工對象物1內部產生多光子吸收形成重整領域 7。因此，由於在力卩工對象物1之表面3上雷射光L幾乎沒 有被吸收，所以加工對象物1之表面3不會造成熔融。 當在加工對象物1內部形成切斷起點領域8時，由於將 此切斷起點領域8作爲起點而容易產生破裂，如第6圖所 示，能夠利用比較小之力量切斷加工對象物1。因此，不 會令加工對象物1之表面3產生不必要之破裂，能夠以高 準確度切斷加工對象物1。 將前述切斷起點領域8作爲起點之加工對象物1之切 斷，存有下面2種方式受到考慮。其一係在形成切斷起點 領域8之後，藉由對加工對象物1施加人爲力量之方式， 將切斷起點領域8作爲起點加工對象物1進行破裂，加工 -10- 200539978 對象物1受到切斷之情況。例如，加工對象物1之厚度大 的情況之切斷。所謂的施加人爲力量，係例如藉由沿著加 工對象物1之切斷起點領域8對加工對象物1施加彎曲應 力或是剪斷應力，藉由對加工對象物1給予溫度差之方式 使熱應力產生。另一種，係藉由形成切斷起點領域8之方 式，將切斷起點領域8作爲起點而朝向加工對象物1之剖 面方向（厚度方向）自然地破裂，結果性地加工對象物1 受到切斷之情況。這是例如加工對象物1厚度小的情況 下，藉由1列之重整領域7可形成切斷起點領域8，在加工 對象物1之厚度大的情況下，藉由在厚度方向上複數列形 成之重整領域7可形成切斷起點領域8。此外，在自然地 破裂之情況下，在切斷之處，直到未形成切斷起點領域8 之部位所對應之部位之表面3上爲止破裂不會先發生，僅 在形成切斷起點領域8之部位所對應之部分能夠進行切 割。近幾年來，由於矽晶圓等之加工對象物1之厚度有變 薄之趨勢’所以如前述之控制性好之切割方法非常有效。 接下來’在本實施形態之雷射加工方法中，藉由多光子 吸收形成重整領域方面，存有下面（丨）〜（3 )之情況。 (1)重整領域係含有丨個或者複數個裂紋之裂紋領域之 情況 在加工對象物（例如是由玻璃或是L i T a 0 3所組成之壓電 材料）之內部處令聚光點聚合，以聚光點之電場強度爲lx 108(W/cm2)以上並且脈衝波寬度爲1 # δ以下之條件來照射 雷射光。前述脈衝波寬度之大小，不會給予持續產生多光 子吸收之加工對象物的表面多餘之損壞，僅藉能夠在加工 -11 - 200539978 對象物內部形成裂紋領域之條件。由此，在加工對象物內 部會產生因多光子吸收所造成之光學性損傷之現象。藉由 此光學性損傷在加工對象物內部會引發出熱歪斜，由此加 工對象物內部會形成裂紋領域。作爲電場強度之上限値， 例如是lxl〇12(W/cm2)。脈衝波寬度例如是以ins〜200ns爲 佳。又，藉由多光子吸收所產生之裂紋領域的形成，係例 如在第45次雷射熱加工硏究會論文集（1998年12月）的第 23頁〜第28頁中的「固體雷射高調波所造成之玻璃基板之 內部記號」中有所記載。 本發明者係藉由根據實驗求出了電場強度與裂紋之大 小的關係。實驗條件是如同以下所述。 (A) 加工對象物：派雷克斯（註冊商標）玻璃（厚度700 # m) (B) 雷射 光源：半導體雷射激發Nd : YAG雷射 波長：1 0 6 4 n m 雷射光照射點截面積：3.14xl〇_8em2 振動形態：Q開關脈衝波 重複的頻率：1〇〇 kHz 脈衝波寬度：30ns 輸出：輸出< lmJ/脈衝波 雷射光品質：TEM。。 偏光特性：直線偏光 (C) 聚光用透鏡 對雷射光波長的透射率：60% (D) 加工對象物被載置之載置台的移動速度：i〇〇mm/秒 -12- 200539978 又，雷射光品質爲TEMqq係指聚光性高直到雷 長程度爲止能夠進行聚光。 第7圖所不係前述實驗之結果的圖表。橫座標 功率密度，由於雷射光爲脈衝波雷射光，所以電 以峰値功率密度加以顯示。縱座標軸係代表藉i 之雷射光在加工對象物內部形成之裂紋部分（裂系 大小。裂紋照點聚集成爲裂紋領域。裂紋照點的 紋照點其形狀中最大長度之部分的大小。圖表中 示之數據係聚光用透鏡（C)的倍率爲100倍，開口 0.8 0之情況。另一方面，圖表中之白點所示之數 用透鏡（C)的倍率爲50倍，開口數（NA)爲0.55之 値功率密度由lxlOHiW/cm2)程度起在加工對象物 生裂紋照點，可得知伴隨著峰値功率密度增大裂 會變大。 接著，針對因裂紋領域形成所產生之加工對象 的機構，參照第8圖〜第1 1圖加以說明。如第8 在產生多光子吸收之條件下在加工對象物1內部 P聚合後照射雷射光L，沿著預定切斷線在內部形 域9。裂紋領域9係含有一個或是複數個裂紋之 前述形成之裂紋領域9會成爲切斷起點領域。如 示，將裂紋領域9作爲起點（也就是，將切斷起點 起點）裂紋會進一步擴大，如對第10圖所示，裂 工對象物1的之表面3與背面21，如對第1 1圖所 加工對象物1分裂之方式加工對象物1受到切斷 工對象物1之表面3和背面2 1之裂紋存有自然地 射光的波 軸係峰値 場強度係 個脈衝波 交照點）的 大小係裂 之黑點所 數（NA)爲 據係聚光 情況。峰 內部會產 紋照點也 物之切斷 圖所示， 令聚光點 成裂紋領 領域。如 第9圖所 領域作爲 紋到達加 :示，藉由 。到達加 成長之情 -13- 200539978 況，亦存在有藉由將力量施加於加工對象物丨而成長之情 況。 (2)重整領域爲熔融處理領域之情況 令聚光點加工對象物（例如二氧化矽般之半導體材料）內 部聚合，在聚光點之電場強度在lxl〇8(W/cm2)以上，並且 脈衝波寬度在1 // s以下之條件來照射雷射光。藉此加工對 象物之內部會由於因爲多光子吸收而被局部地加熱。藉由 該加熱加工對象物之內部會形成熔融處理領域。所謂的熔 融處理領域係指一旦熔融之後再凝固化之領域，也正是熔 融狀態之領域，或是由熔融狀態成爲再次凝固地化狀態之 領域，亦可稱爲相變化後之領域或是結晶構造變化後領 域。另外，所謂的熔融處理領域，已可稱爲在單結晶構造、 非晶質構造、多結晶構造方面，由某種構造變化形成其他 種構造之領域。也就是說意味著，例如，由單結晶構造變 化形成非晶質構造之領域、由單結晶構造變化形成多結晶 構造之領域、包含由單結晶構造變化形成含有非晶質構造 以及多結晶構造之構造的領域。加工對象物是矽單結晶構 造之情況下，例如，熔融處理領域可以是非晶質矽構造。 在作爲電場強度之上限値上，例如以lxl〇12(W/cm2)爲佳。 脈衝波寬度例如以Ins〜200ns爲佳。 本發明者由實驗可確認在矽晶圓內部形成有熔融處理 領域之事。實驗條件係如以下所述。 (A) 加工對象物：矽晶圓（厚度3 50 // m、外徑4英寸） (B) 雷射 光源：半導體雷射激發Nd : YAG雷射 -14- 200539978 波長：1 0 6 4 n m 雷射光地點截面積：3.141xl(T8cm2 振動形態：Q開關脈衝波 重複的頻率：100kHz 脈衝波寬度：30ns 輸出：20//〗/脈衝波 雷射光質量：TEM。。 偏光特性：直線偏光 (C) 聚光用透鏡 倍率：5 0倍 N . A . : 0.55 對雷射光波長的透射率：60 % (D) 加工對象物被載置的載置左右的移動速度：100mm/ 秒 第1 2圖係在上述條件下藉由雷射加工所切斷之矽晶圓 之一部分其剖面之照片圖。矽晶圓1 1之內部形成有熔融處 理領域1 3。又，由上述條件所形成之熔融處理領域1 3其厚 度方向的大小爲1 0 0 V m程度。 接著說明熔融處理領域1 3係藉由多光子吸收所形成。 第1 3圖係說明雷射光之波長與矽基板內部之透射率之關 係的圖。但是，排除矽基板表面端與背面端之各反射成分， 僅表示內部之透射率。分別針對矽基板之厚度t爲50 // m、 100//m、200#m、500#m、1000/zm 說明前述關係。 例如，在Nd : YAG雷射之波長爲1 064 nm下，矽基板之 厚度爲500 // m以下之情況下，得知在矽基板內部雷射光會 -15- 200539978 有80%以上透射過。如第12圖所示之矽晶圓1 1之厚度爲 3 5 0 // m，所以由多光子吸收所產生的熔融處理領域1 3在矽 晶圓1 1之中心附近，也就是形成於從表面算起1 75 // m之 部分處。在此情況之透射率，參考厚度爲200 /z m之矽晶圓 的話，由於在90%以上，所以雷射光在矽晶圓1 1內部被吸 收的僅有少數，幾乎透射過矽晶圓。此現象係意味著，並 非是雷射光在矽晶圓1 1之內部受到吸收，在矽晶圓1 1之 內部形成熔融處理領域1 3 (也就是說，因雷射光所造成之一 般加熱而形成熔融處理領域），而是熔融處理領域1 3藉由 多光子吸收而形成。由多光子吸收所產生之熔融處理領域 的形成，例如，熔接學會全國大會講演槪要第66集（2000 年4月）之第72頁〜第73頁中「由於微微秒脈衝波雷射之 矽晶之加工特性評價」有所記載。 又，矽晶圓，係將由熔融處理領域所形成之切斷起點領 域作爲起點朝著剖面方向令破裂產生，藉由該破裂到達矽 晶圓之表面與背面之方式結果性地達成切斷。到達矽晶圓 之表面與背面之破裂，存有自然地成長之情況，亦存在有 藉由施力於矽晶圓而成長之情況。然後，從切斷起點領域 起到矽晶於表面與背面之破裂爲自然地成長之情況下，存 有在破裂係由形成切斷起點領域之熔融處理領域爲熔融之 狀態開始成長之情況，以及亦存在有破裂由形成切斷起點 領域之熔融處理領域爲熔融之狀態開始再次凝固化之際進 行成長之情況。但是，任何一種情況中熔融處理領域僅形 成於矽晶圓之內部，切斷後的切斷面處，係如第1 2圖所示 僅有在內部形成有熔融處理領域。如此，在加工對象物內 -16- 200539978 部藉由熔融處理領域而形成切斷起點領域時，於切斷時， 不易產生由切斷起點領域線脫落之不必要之破裂，所以切 斷控制變得容易。 (3 )重整領域是折射率變化領域之情況 令聚光點在加工對象物（例如玻璃）內部聚合，在聚光點 之電場強度爲lxl08(W/cm2)以上並且脈衝波寬度爲Ins以 下的條件照射雷射光。將脈衝波寬度變爲相當短，令加工 對象物內部產生多光子吸收時，因多光子吸收所產生之能 量不會轉化爲熱能，加工對象物內部之離子價數變化、結 晶化或者分極配向等之長久性構造變化會受到誘導而形成 折射率變化領域。作爲電場強度的上限値，例如以1 X 1012(W/cm2)爲佳。脈衝波寬度例如以Ins以爲佳。以lps 以下爲更佳。由多光子吸收所產生之折射率變化領域的形 成，例如在第42次雷射熱加工硏究會論文集（ 1 997年11月） 的第105頁〜第111頁中之「億萬分之一秒雷射照射所產生 之對於玻璃內部之光誘發構造形成」有所記載。 以上，係針對多光子吸收所形成之重整領域之（1)〜（3)之 情況進行說明，如果考慮晶圓狀之加工對象物之結晶構造 或是其剖開性等而以下所述般形成切斷起點領域的話，將 該切斷起點領域作爲起點，能夠以更小一層之力量，而且 準確度良好地切斷加工對象物。 也就是說，在由矽晶等之金剛石構造之單結晶半導體所 組成之基板之情況下，以沿著（1 1 1)面（第1剖開面）與（1 10 ) 面（第2剖開方面）之方向上形成切斷起點領域爲佳。另外， 在由GaAs等之閃鋅礦型構造之III-V族化合物半導體所組 -17- 200539978 成之基板之情況，以沿著（11 ο )面之方向上形成切斷起點 領域爲佳。此外，有藍寶石（Al2〇3)等之六方晶體系列之結 晶構造之基板之情況下，係以（〇 0 〇 1)面（c面）作爲主面而沿 著（1120)面（A面）或是（1100)面（M面）之方向上形成切斷起 點領域爲佳。 此外，在應形成前述切斷起點領域之方向（例如沿著單 結晶矽基板之（11 1)面之方向），或者是沿著與應形成切斷起 點領域之方向垂直之方向在基板上形成定位平面的話，利 B 用將該定位平面作爲基準之方式，能夠將沿著應形成切斷 起點領域之方向容易且正確地在基板上形成切斷起點領 域。 以下，將針對本發明之加工對象物切斷方法之合適之實 施形態加以說明。第15圖〜第17圖係沿著第14圖之矽晶 圓XV-XV線之部分之剖面圖。 如第14圖所示，成爲加工對象物之矽晶圓（半導體基 板）11之表面3上，複數個功能元件15在與定位平面16平 φ 行之方向以及垂直之方向以矩陣狀模樣加以形成。將前述 之矽晶圓1 1如以下所述般針對每一功能元件1 5進行切 斷。 首先，如第1 5 (a)圖所示，矽晶圓1 1表面3黏合有雙面 膠帶17。該雙面膠帶17其矽晶圓端之黏合劑層17 a，會因 紫外線的照射而使黏合力下降，且在與矽晶圓1 1之界面產 生氣體，令矽晶圓1 1自行剝離。在前述自己剝離型之雙面 膠帶17，例如有積水化學工業股份公司之「塞爾法 (SELFA)(商品名）」。然後，如第15(b)圖所示，與雙面膠 -18- 200539978 帶1 7其矽晶圓1 1相反側之黏合劑層1 7 b處年貼有玻璃製 之形狀維持板（形狀維持體）1 8。如此，由於形成有功能元 件1 5之矽晶圓1 1之表面3安裝有形狀維持板丨8，所以能 夠保護功能元件1 5。 接著，如第1 5 (c)圖所示，在表面3上安裝形狀維持板 1 8之狀態下將砂晶圓1 1搬運到硏削裝置5 0，在硏削裝置 5 0之加工台5 1上，將矽晶圓1 1背面2 1朝向上方然後將形 狀維持板1 8加以固定。然後，將矽晶圓1 1之背面藉由旋 φ 轉磨石5 2進行平面硏削，例如，將厚度3 5 0 // m之矽晶圓 1 1薄型化爲厚度1 00 μ m。透過使用前述之形狀維持板1 8 之方式，保護矽晶圓1 1之表面3與形成於表面3之功能元 件1 5，並且能夠防止矽晶圓1 1變形，使矽晶圓1 1薄型化。 接著，如第16(a)圖所示，在表面3上安裝形狀維持板 1 8之狀態下將矽晶圓1 1搬運到雷射加工裝置60，在雷射 加工裝置 60之加工台61上，將矽晶圓11之背面21朝向 上方然後將形狀維持板1 8加以固定。然後，通過相鄰之功 ^ 能元件1 5、1 5之間將預定切斷線5依格子狀加以設定（參 照第1 4圖之兩點鎖線），將背面2 1作爲雷射光射入面在矽 晶圓1 1之內部將聚光點P聚合，在產生多光子吸收之條件 下一邊照射雷射光L，一邊藉由加工台6 1的移動令聚光點 P沿著預定切斷線5作相對移動。由此，在矽晶圓1 1之內 部，如第16(b)圖所示，沿著預定切斷線5形成由領域熔融 * 處理13所產生之切斷起點領域8。如此，藉由矽晶圓11 - 之背面2 1作爲雷射光射入面之方式’例如即使功能元件1 5 存在有將雷射光L反射之部分，亦能夠在矽晶圓1 1之內部 -19- 200539978 確實地形成切斷起點領域8。 接著’將安裝有形狀維持板1 8之矽晶圓1 1係從加工台 61卸下’如第16(〇圖所示，利用膠帶黏貼機（未圖示），在 石夕晶圓1 1之背面2 1，黏貼上貼擴展膠帶（可擴張薄膜）1 9。 _ ί廣Μ膠帶1 9其外周圍部分係黏貼於呈環狀之膠帶固定 框2 2 ’固定於此固定框2 2。 ί妾著1 ’如第17(a)圖所示，在背面21將黏貼有擴展膠帶 1 9之砂晶圓丨丨，在表面3上安裝有形狀維持板1 8之狀態 Φ Τ搬運到薄膜擴張裝置70,利用將膠帶固定框22利用環狀 之承接元件7 1以及環狀之推壓元件72加以挾持之方式， 將砂晶圓1 1安裝於薄膜擴張裝置70。在此狀態下從形狀維 持板1 8端照射紫外線，藉由令黏合劑層1 7 a的黏合力下 降’並且在矽晶圓11之界面產生氣體之方式，從矽晶圓Η 之表面3處卸下雙面膠帶丨7以及形狀維持板丨8。然後，如 第1 7 (b)圖所示，令配置於承接元件7 1內側之呈圓柱狀之 推壓元件73從擴展膠帶19下端上升，如第17 (c)圖所示， φ 藉由令擴展膠帶19擴張之方式，以切斷起點領域8作爲起 點將砂晶圓1 1切斷的同時，令受到切斷之各晶片2 3互相 分離產生。由此，能夠容易且正確地將各晶23加以擷取。 在以上所說明之加工對象物切斷方法中，從將矽晶圓i ! 之背面2 1作爲雷射光射入面而沿著預定切斷線5在砂晶圓 1 1之內部形成由熔融處理領域1 3所產生之切斷起點領域8 • 之際，直到矽晶圓1 1之背面2 1黏貼上擴展膠帶1 9爲止， -砂晶圓1 1之表面3安裝有形狀維持板1 8。藉由此形狀維持 板1 8，爲能夠確實地防止矽晶圓1 1之變形，形成有切斷起 -20- 200539978 • · 點領域8之矽晶圓1 1之處理能夠容易化。接著，藉由從矽 晶圓1 1之表面3卸下形狀維持板1 8，令擴展膠帶1 9擴張 之方式’將切斷起點領域8作爲起點而矽晶圓1 1受到切 斷所產生之複數個晶片互相分離。由此，形成有切斷起點 領域8之矽晶圓1 1，由於其變形經過確實地受到防止之狀 態切斷成複數個晶片23，所以能夠防止受到切斷所產生之 複數個晶片23上產生碎屑和裂化等之不合適現象。 另外，切斷起點領域8之形成係在雷射加工裝置6 0上 進行，由於形狀維持板1 8之卸下以及各晶片23之分離係 在薄膜擴張裝置70上進行，所以能夠將各裝置60、70之 構成簡易化。然後，在從雷射加工裝置60對於薄膜擴張裝 置70之矽晶圓1 1的搬運方面，雖然矽晶圓1 1之內部形成 有切斷起點領域8，但是由於矽晶圓1 1之表面3安裝有形 狀維持板1 8，所以能夠防止如在搬運期間以切斷起點領域 8作爲起點矽晶圓1 1不小心地受到切斷之事態。 接著，針對以上所述之薄膜擴張裝置70之構成加以說 明。如第18圖〜第20圖所示，薄膜擴張裝置70係具有承 受元件7卜推入元件72、設置有推壓元件73之本體部74、 以及倂排設置於本體部74之承載台75。本體部74安裝有 開關自如之蓋體79，在蓋體79之背面安裝有紫外線燈76。 此外，在主體部74，更安裝有其前端固定有吸附襯墊77 之搖動自如之臂78。 接下來針對前述構成之薄膜擴張裝置70之使用方法說 明。首先，如第18(a)圖所示，在蓋體79開放之狀態下藉 由承受元件7 1以及推入元件72將矽晶圓1 1裝設於薄膜擴 -21- 200539978 張裝置70。然後’如第18(b)圖所示，關閉蓋體79，在此 狀態下藉由紫外線燈75從形狀維持板1 8端照射紫外線。 由此，能夠從矽晶圓1 1之表面3將雙面膠帶1 7以及形狀 維持板1 8卸下。 接著，如第19圖U)所示，將蓋體79開放，在此狀態下 令臂78搖動令吸附襯墊77在形狀維持板1 8上移動，藉由 吸附襯墊7 7吸附形狀維持板1 8。之後，如第1 9 (b)圖所示， 令臂78搖動使雙面膠帶17以及形狀維持板18在載置台75 移動。然後，如第20圖所示，令推壓元件7 3從擴展膠帶 19之下端上升，藉由令擴展膠帶19擴張之方式，以切斷起 點領域作爲起點令矽晶圓1 1受到切斷所產生之各晶片互 相分離產生。 本發明並未受限於前述實施形態。例如，上述實施形態 中，雖然有在加工對象物1之內部令多光子吸收產生形成 重整領域7之情況，亦存在有能夠在加工對象物1之內部 使其產生與多光子吸收和同等之光吸收而形成重整領域7 之情況。 另外，在前述實施形態，藉由令擴展膠帶1 9擴張之方 式，將以切斷起點領域8作爲起點的矽晶圓1 1切斷的同 時，令受到切斷而產生之各晶片23讓互相分離之情況，但 本發明並非限定於此。例如，在形狀維持板1 8安裝於表面 3上之狀態下，藉由對於形成於切斷起點領域8之矽晶圓 1 1由背面2 1端施加熱應力等之外力之方式，亦可以在令擴 展膠帶1 9之前，以切斷起點領域8作爲起點將矽晶圓Π ° 另外，在矽晶圓1 1之內部形成切斷起點領域8之後’ -22- 200539978 砂晶圓11之背面21黏貼擴展膠帶19之前，在表面3上安 衣有形狀維ί寸板1 8之狀態下，對砂晶圓丨1之背面2 1進行 硏磨，例如，亦可以將厚度1 00 # m之矽晶圓11更一層地 薄型化厚度5 0 /Z m〜2 5 /z m。在此情況，亦能夠保護砂晶圓 1 1之表面3，並且持續防止矽晶圓1 1之變形，更能達成矽 晶圓1 1之薄型化。 另外，在上述實施形態中，雖然形狀維持板1 8是玻璃 製之情況，形狀維持板1 8，只要是具有防止受到安裝之矽 晶圓1 1之變形程度之剛性即可（例如，亦可是丙烯樹脂等 樹脂製）。但是，如前述實施形態，將玻璃製之形狀維持板 1 8經由黏合劑層1 7 a安裝於砂晶圓1 1之表面3上，另一 方面，只要是藉由從形狀維持板1 8側將紫外線照射到黏合 劑層17 a令黏合劑層17 a的黏合力下降，從矽晶圓π之 表面3卸下形狀維持板1 8的話，容易進行對於矽晶圓丄i 之表面3其形狀維持板18之安裝、卸下。此外，爲了將形 狀維持板塊18安裝於矽晶圓11之表面3上用令其介入之 黏合劑層，藉由紫外線之外的電磁波之照射或者加熱使黏 合力下降物件亦可以。由此，藉由對黏合劑層照射電磁波 之方式，或者是藉由對黏合劑層加熱之方式令黏合劑層之 黏合力下降，能夠容易從砍晶圓1 1之表面3卸下形狀維持 板1 8 〇 又，上述實施形態，形狀維持體係形狀維持板1 8的情 況，形狀維持體可以是複數張保護薄膜互相黏合之物件。 在此情況下，如第21 (a)圖所示，矽晶圓11之表面3黏貼 保護薄膜25之後，在硏削裝置50之加工台5 1上，將Ϊ夕晶 -23- 200539978 圓1 1之背面2 1朝向上方然後固定矽晶圓1 1，將矽晶圓1 1 之背面2 1藉由轉動砥石5 2進行平面硏削將矽晶圓1 1薄型 化。接著，如第21(b)圖所示，膠帶固定器80的吸附台81 上’將矽晶圓1 1之表面3朝向上方將矽晶圓1 1加以固定， 進而已經黏貼於保護薄膜25上，進一步黏貼1張或者複數 張之保護薄膜25。之後，將藉由互相黏貼之方式而能夠獲 得具有防止矽晶圓1 1其變形程度之剛性之複數張保護薄 膜25作爲形狀維持體，進行與前述述實施形態相同之製 Φ 程。又’矽晶圓1 1之表面3容易將保護薄膜25剝下之電 磁波（例如紫外線）的照射，係在將複數張保護薄膜25互相 黏合以後，只要是在薄膜擴張裝置70中從矽晶圓1 1之表 面3將複數張保護薄膜25剝下爲止之間的話，任何時候均 可以進行。另外，將保護薄膜25 —張一張分別剝下之情況 下，以其分別剝下之時序，照射電磁波（例如紫外線）亦可。 此外’形狀維持體可以是黏貼於砂晶圓1 1之表面3之 保護薄膜2 5與形狀維持板1 8互相黏合之物件。在此情況 φ 中’如第2 2 (a)圖所示，矽晶圓1 1之表面3黏貼保護薄膜 2 5之後，在硏削裝置 5 0之加工台5 1上，將矽晶圓1 1之 背面2 1朝向上方而將矽晶圓1 1加以固定，將矽晶圓11之 背面2 1藉由轉動砥石5 2進行平面硏削將矽晶圓丨丨薄型 化。接著，如第22(b)圖所示，膠帶固定器80的吸附台81 上’將Ϊ夕晶圓1 1之表面3朝向上方將砂晶圓1 1加以固定， 進而已經黏貼於保護薄膜25上，進一步黏貼形狀維持板 - 1 8。之後，將保護薄膜2 5以及形狀維持板1 8作爲形狀維 持體，進行與前述實施形態相同之製程。又，矽晶圓1 1之 -24- 200539978 表面3容易將保護薄膜25以及形狀維持板1 8剝下之紫外 線的照射’係在將形狀維持板1 8黏貼於保護薄膜25以後， 只要是在薄膜擴張裝置70中從矽晶圓1 1之表面3將保護 薄膜25以及形狀維持板1 8剝下爲止之間的話，任何時候 均可以進行 (產業上的利用可能性） 若依據本發明則能夠將形成有起點領域被之加工對象 物的處理容易化，並且能夠防止將切斷起點領域作爲起點 而加工對象物受到切所產生之複數個部分產生碎屑和破裂 等的不合適現象。 【圖式之簡單說明】 第1圖係根據本實施形態之雷射加工方法進行雷射加工 之加工對象物之平面圖。 第2圖係沿著第1圖所示之加工對象物的II-II線之剖視 圖。 第3圖係根據本實施形態的雷射加工方法進行雷射加工 之後的加工對象物之平面圖。 第4圖係沿著第3圖所示之加工對象物的IV-IV線之剖 視圖。 第5圖沿著第3圖所示之加工對象物的V-V線之剖視圖。 第6圖係藉由本實施形態之雷射加工方法受到切斷之加 工對象物之平面圖。 第7圖係說明在本實施形態之雷射加工方法中其電場強 度和裂紋照點的大小之關係之圖。 第8圖是在本實施形態之雷射加工方法之第1製程中之 -25- 200539978 加工對象物之剖視圖。 第9圖是在本實施形態之雷射加工方法之第 加工對象物之剖視圖。 第1 0圖是在本實施形態之雷射加工方法之 之加工對象物之剖視圖。 第1 1圖是在本實施形態之雷射加工方法之 之加工對象物之剖視圖。 第1 2圖係說明藉由本實施形態之雷射加工 P 斷肢矽晶圓之一部分其剖面的照片圖。 第1 3圖係顯示在本實施形態的之雷射加工 射光之波長與矽晶基板內部之透射率之關係之 第1 4圖係在本實施形態之加工對象物切斷 爲加工對象物的矽晶圓之平面圖。 第1 5圖係用於說明本實施形態之加工對象 之示意圖，（a)係矽晶圓貼合有雙面膠帶之狀態 膠帶貼合於形狀維持板之狀態，（c)係正在對矽 $ 削之狀態。 第1 6圖係用於說明本實施形態之加工對象 之示意圖，（a)係矽晶圓正在照射雷射光之狀態 晶圓內部形成切斷起點領域之狀態，（c)係矽晶 擴展膠帶的狀態。 第1 7圖係用於說明本實施形態之加工對象 ’之示意圖，U)係在薄膜擴張裝置中照射紫外線 係在薄膜擴張裝置中令推壓元件上升之狀態、 擴張裝置中各晶片互相分離之狀態。 2製程中之 第3製程中 第4製程中 方法受到切 方法中，雷 曲線圖。 方法中，成 物切斷方法 ，（b)係雙面 晶圓進行硏 物切斷方法 、（b)係在矽 圓上貼合有 物切斷方法 的狀態、（b) (〇係在薄膜 -26- 200539978 弟1 8圖係本貫施形態之薄膜擴張裝置之斜視圖，（a)係 安裝有矽晶圓的狀態、（b)係照射紫外線的狀態。 第1 9圖係本實施形態之薄膜擴張裝置之斜視圖，（a)係 將吸附襯墊向形狀維持板上移動之狀態、（b)係將雙面膠帶 以及形狀維持板移動到承載台上之狀態。 第20圖係本實施形態之薄膜擴張裝置之斜視圖，係令 推壓元件上升之狀態。 第2 1圖係用於說明本實施形態之加工對象物切斷方法 φ 其變形例之示意圖，U)係將矽晶圓進行硏削之狀態、（b) 係在保護薄膜上貼合保護薄膜之狀態。 第22圖係用於說明本實施形態之加工對象物切斷方法 其變形例之示意圖，（a)係將矽晶圓進行硏削之狀態、（b) 係在保護薄膜上貼合形狀維持板之狀態。 【主要元件符號說明】 1…加工對象物 3 …表面 ^ 5…預定切斷線 7…重整領域 8…切斷起點領域 Π …矽晶圓（半導體基板） 13…熔融處理領域 15…功能元件 ' 18…形狀維持板（形狀維持體） • 19…擴展膠帶（可擴張薄膜） 21…背面（雷射光射入方面） -27- 200539978 23 …晶片 25 …保護薄 膜 60 …雷射加 工 裝 置 70 …薄膜擴 張 裝 置 L ·· •雷射光 P ·· •聚光點200539978 Xin IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a method for cutting a processing object by cutting a wafer-shaped processing object along a predetermined cutting line. [Prior Art] In the prior art of this type, the following laser processing method is described in Patent Literature / Japanese Patent Laid-Open No. 2004-1 076 described below. In other words, a flat-shaped processing object is provided with an element that protects its surface, and the laser beam is irradiated by using the back surface of the processing object as the laser light incident surface to form a processing line along a predetermined cutting line. The cut-off starting area is formed by the reforming area inside the object. Next, a method of installing a stretchable film on the back surface of the object to be processed and extending the stretchable film is to 'cut the starting point region as a starting point to cut the object to be processed so that a plurality of parts generated each other Separation. Patent Document 1: Japanese Patent Publication No. 2004-1 076. [Summary of the Invention] [Disclosure of the Invention] [Problems to be Solved by the Invention] However, in the aforementioned laser processing method, the object to be processed having a cutting start area is easily cut off using the cutting start area as a starting point. In the case of cutting the processing object using the cutting starting area as the starting point, the generated multiple parts will be in a state of being closely connected to each other. Therefore, for example, in the case of using a protective film as a protective surface element, in order to prevent unsuitable phenomena such as chipping and cracking of a plurality of parts generated by cutting, care must be taken to form the starting point of cutting 200539978 Processing objects in the field. Therefore, the present invention has been made in view of the foregoing circumstances, so as to facilitate the processing of a processing object formed with a cutting start region and prevent the processing object from being cut by using the cutting start region as a starting point. The purpose is to cut off the chips, cracks, etc., which are generated in a plurality of parts, by inappropriate cutting methods. (Means for Solving the Problem) In order to achieve the above-mentioned object, a method for cutting an object to be processed according to the present invention is a method for cutting an object to be processed along a predetermined cutting line, and is characterized in that Including the state where a shape maintaining body is mounted on the surface of the processing object, the rear surface of the processing object is used as a laser light incident surface, and the focusing point is aggregated inside the processing object, and the laser light is irradiated to form a reforming Field, according to the reforming field, a process of forming a cutting starting area from a laser light incident surface inside a predetermined distance along a predetermined cutting line; and mounting on the back of a processing object forming the cutting starting area A process of expanding a film; a process of removing a shape maintaining body from a surface of a processing object on which the expandable film is mounted; and expanding the expandable film, using the cutting starting area as a starting point, and cutting the processing object The process of producing a plurality of parts separated from each other. In this method for cutting a processing object, the rear surface of the processing object is used as a laser light incident surface, and the cutting starting area is formed by reforming the area inside the processing object along a predetermined cutting line until Until the expandable film is mounted on the back surface of the processing object, a shape maintaining body is mounted on the surface of the processing object. With this shape maintaining body, deformation of the processing object can be reliably prevented, so that processing of the 200539978 object can be facilitated by the process of forming the cutting starting area. Then, by removing the shape-maintaining body from the surface of the object to be processed, the expansion film can be expanded, and the cutting starting area is used as a starting point to cut and separate the generated plural parts from each other. As a result, the object to be processed having the starting point of cutting is cut into a plurality of parts after undergoing a state in which deformation is surely prevented. Therefore, it is possible to prevent chipping and cracking of the plurality of parts generated by the cutting. Waiting for inappropriateness. Here, the starting point area for cutting refers to the area that becomes the starting point of cutting when the processing object is cut. This cut-off starting area may be formed due to the continuous formation of the reformed area, and may also be formed intermittently from the reformed area. The reforming field is formed by merging the condensing points inside the processing object to irradiate the laser light, and is formed by multiphoton absorption or equivalent light absorption in the processing object. The process of forming the cut-off point area is preferably performed in a laser processing apparatus, and the process of removing the shape maintaining body and the process of separating a plurality of parts from each other are preferably performed in a thin film expansion apparatus. By using such a laser processing device and a thin film expansion device, the configuration of each device can be simplified. Then, from the laser processing device to the processing object of the film expansion device, although the cutting starting area is formed inside the processing object, the shape maintaining body is mounted on the surface of the processing object, so it can be prevented from being transported. In the case where the cutting start area is used as a starting point, the processing object is cut unexpectedly. Further, in the case of a semiconductor substrate having a functional element formed on the surface of the object to be processed, the shape maintaining body is mounted on the surface of the semiconductor substrate, so that the functional element can be protected. Furthermore, for example, even if there is a part reflecting the laser light on the functional element 200539978 雠 1, the back surface becomes the laser light incident surface in the process of forming the cut-off point area, so the cut-off point area can be reliably formed in the semiconductor substrate . Therefore, the so-called functional elements include, for example, a semiconductor operating layer formed by crystal growth, a photosensitive element such as a photodiode, a light emitting element such as a laser diode, and a circuit element formed as a circuit. In addition, before the process of cutting the starting point area is formed, the state where the shape maintaining body is mounted on the surface of the processing object may include a process for honing the back surface of the φ object, or it may be formed. Between the process of cutting the starting area and the process of mounting the expandable film, the process of honing the back surface of the processing object while the shape maintaining body is mounted on the surface of the processing object is included. This makes it possible to protect the surface of the processing object, prevent deformation of the processing object, and reduce the thickness of the processing object. In order to reduce the thickness of the semiconductor substrate in accordance with the miniaturization of the semiconductor device, it is extremely effective when the object to be processed is a semiconductor substrate. Therefore, the so-called honing refers to the meaning of cutting, honing, chemical etching, etc. In addition, the shape maintaining body is made of glass or resin, and can be mounted on the surface of the object through an adhesive layer. In the process of removing the shape maintaining body, the method of irradiating electromagnetic waves on the adhesive layer from the side of the shape maintaining body, or heating the adhesive layer to reduce the adhesive force of the adhesive layer, and remove it from the surface of the object to be processed. A shape maintaining body is preferable. This makes it possible to easily attach and detach the shape maintaining body on the surface of the object to be processed. (Effects of the Invention) 200539978 1 According to the present invention, it is possible to facilitate the processing of the processing object forming the cutting starting area, and to prevent the processing object from being cut by using the cutting starting area as the starting point. Defects such as chipping and cracking occur in each part. [Embodiment] Hereinafter, an embodiment of a method for cutting a processing object suitable for the present invention will be described in detail with reference to the drawings. In this embodiment, a phenomenon called multiphoton absorption is used because a reforming region is formed inside the object to be processed. Therefore, a laser processing method for forming a reforming field by multiphoton absorption will be described from the beginning. The energy h of the photon is smaller than the band gap EG that the material absorbs, and it becomes optically transparent. Therefore, the condition under which the material generates absorption is hv > EG. However, even if it is optically transparent, when the intensity of the laser light becomes very large, the material absorbs under the condition of nh p > EG (n = 2, 3, 4, ...). This phenomenon is called multiphoton absorption. In the case of a pulse wave, the intensity of the laser light is determined by the peak-to-peak power density (W / cm 2) of the focal point of the laser light. For example, when the peak-to-peak power density is lxl 08 (W / cm 2) or more Under these conditions, multiphoton absorption will occur. The peak chirp power density is obtained by (energy per unit of pulse wave of laser light at the condensing point) + (cross-sectional area of laser beam irradiation point X pulse wave width). In the case of a continuous wave, the intensity of the laser light is determined by the electric field intensity (W / cm2) of the focal point of the laser light. The principle of the laser processing method of the present embodiment using multiphoton absorption will be described with reference to FIGS. 1 to 6. As shown in Fig. 1, a predetermined cutting line 5 for cutting the processing object 1 exists on the surface 3 of the wafer-shaped (flat-plate) processing object 1. The planned cutting line 5 is an imaginary line extending in a straight line shape of 200539978. In the laser processing method of this embodiment, as shown in FIG. 2, the light-concentrating points P are aggregated under conditions that generate multiphoton absorption, and the laser light L is irradiated to the inside of the processing object 1 to form a reforming area 7 . The condensing point P is a place where the laser light L is condensed. In addition, the predetermined cutting line 5 is not limited to a straight line, and may be a curved line. It is not limited to a virtual line, and may be a line drawn on the object 1 to be actually processed. Then, the laser beam L is relatively moved along the predetermined cutting line 5 (i.e., the direction of arrow A in FIG. 1), so that the light-condensing point P is moved along the predetermined cutting line 5. Thereby, as shown in FIGS. 3 to 5, the reforming area 7 is located inside the object 1 along the predetermined cutting line 5 stroke, and the reforming area 7 becomes the cutting starting area 8. The laser processing method of the present embodiment does not generate the reforming field 7 by heating the processing object 1 by absorbing the laser light L by the processing object 1. Instead, the laser light L is transmitted through the processing object 1 to cause multiphoton absorption inside the processing object 1 to form a reforming area 7. Therefore, since the laser light L is hardly absorbed on the surface 3 of the work object 1, the surface 3 of the work object 1 is not melted. When the cutting starting area 8 is formed inside the processing object 1, the cutting starting area 8 is used as a starting point, so that cracking is likely to occur. As shown in FIG. 6, the processing target 1 can be cut with a relatively small force. Therefore, it is possible to prevent the surface 3 of the processing object 1 from being broken unnecessarily, and it is possible to cut the processing object 1 with high accuracy. The following two methods are considered for cutting the processing object 1 using the cutting starting area 8 as a starting point. One is that after the cutting starting area 8 is formed, the cutting starting area 8 is used as a starting point to rupture the processing target 1 by applying artificial force to the processing target 1. The processing-10- 200539978 Object 1 receives Cut-off situation. For example, cutting is performed when the thickness of the object 1 is large. The so-called artificial force is applied, for example, by applying a bending stress or a shearing stress to the processing object 1 along the cutting start region 8 of the processing object 1 and applying a temperature difference to the processing object 1. Thermal stress is generated. On the other hand, by forming the cutting starting area 8 as a starting point, the cutting starting area 8 is naturally broken toward the cross-sectional direction (thickness direction) of the processing object 1, and as a result, the processing object 1 is cut. Situation. This is, for example, when the thickness of the processing object 1 is small, the cutting starting area 8 can be formed by the reforming field 7 of one row, and when the thickness of the processing object 1 is large, a plurality of rows are formed in the thickness direction. The formed reforming area 7 can form a cutting start area 8. In addition, in the case of natural rupture, the rupture will not occur first at the cutting position until the surface 3 of the part corresponding to the part of the starting point of cutting area 8 is not formed, but only in forming the starting point of cutting area 8 The part corresponding to the part can be cut. In recent years, since the thickness of the processing object 1 such as a silicon wafer tends to become thinner ', the cutting method with good controllability as described above is very effective. Next, in the laser processing method of this embodiment, the following (丨) to (3) may be formed in the reforming field by multiphoton absorption. (1) In the case of a reforming area that contains one or more cracks, a light-condensing point is placed inside the processing object (for example, a piezoelectric material composed of glass or Li T a 0 3). Polymerize, and irradiate the laser light under the conditions that the electric field intensity of the light-condensing point is 1x 108 (W / cm2) or more and the pulse wave width is 1 # δ or less. The size of the aforementioned pulse wave width will not give unnecessary damage to the surface of the processing object that continuously generates multi-photon absorption, and only by the condition that a crack field can be formed inside the processing -11-200539978 object. As a result, optical damage due to multi-photon absorption occurs inside the processing object. This optical damage causes thermal distortion in the object to be processed, and a crack region is formed inside the object to be processed. The upper limit 电场 of the electric field strength is, for example, 1 × 10 12 (W / cm2). The pulse width is preferably, for example, ins to 200 ns. In addition, the formation of crack fields by multiphoton absorption is, for example, "solid lasers" on pages 23 to 28 of the 45th Laser Thermal Processing Research Papers (December 1998). It is described in "Internal Symbols of Glass Substrates Caused by High-Modulation Waves." The inventors determined the relationship between the electric field strength and the size of cracks by experiments. The experimental conditions are as described below. (A) Object to be processed: Perex (registered trademark) glass (thickness 700 # m) (B) Laser light source: semiconductor laser excitation Nd: YAG laser wavelength: 1 0 6 4 nm Laser light irradiation point cut Area: 3.14xl0_8em2 Vibration pattern: Q switching pulse wave repetition frequency: 100kHz Pulse width: 30ns Output: output < lmJ / pulse wave Laser light quality: TEM. . Polarization characteristics: Linear polarized light (C) Condensing lens for laser light wavelength transmittance: 60% (D) Moving speed of the stage on which the object to be processed is placed: 〇〇mm / sec-12- 200539978 The laser light quality of TEMqq means that light condensing can be performed until the degree of light condensing is high. Figure 7 is not a chart of the results of the previous experiments. The abscissa power density. Since the laser light is a pulse wave laser light, the electric power is displayed by the peak chirp power density. The axis of the ordinate represents the crack portion (crack size) formed inside the processing object by the laser light of i. The size of the crack spot gathers into the crack area. The size of the largest length in the shape of the grain spot of the crack spot. In the chart The data shown is a case where the magnification of the lens (C) for condensing is 100 times and the opening is 0.8 0. On the other hand, the magnification of the lens (C) for the number shown by the white dot in the graph is 50 times and the number of openings ( NA) of 0.55 has a power density of about 1xlOHiW / cm2) at the point where cracks are generated in the object to be processed. It can be seen that the crack becomes larger with the increase of the peak power density. Next, the mechanism of the object to be processed due to the formation of crack areas will be described with reference to FIGS. 8 to 11. For example, under the condition that multiphoton absorption is generated, laser light L is irradiated in the interior of the processing object 1 after the polymerization of P, and the internal shape 9 is formed along a predetermined cutting line. The crack region 9 is a crack starting region formed by the aforementioned crack region 9 containing one or a plurality of cracks. As shown, the crack area 9 is used as the starting point (that is, the starting point of the cutting starting point). The crack will further expand. As shown in FIG. 10, the surface 3 and the back surface 21 of the cracking object 1 are as shown in FIG. The way the processed object 1 is split is that the processed object 1 is cut off the surface 3 and the back surface 21 of the work object 1 and the cracks of the wave axis system of the natural light are present. The size of the black points (NA) is the light condensing situation. Inside the peak, there will be cut spots and cuts of objects, as shown in the figure, so that the focusing point becomes a crack collar area. As shown in Fig. 9, the area is shown as a ridge reaching plus: with. Reaching and growing -13- 200539978 In some cases, there is also the case of growing by applying power to the processing object. (2) When the reforming field is a melting process field, the object of the light-condensing point (such as a silicon dioxide-like semiconductor material) is polymerized internally, and the electric field intensity at the light-condensing point is 1 × 10 8 (W / cm2) or more. And the pulse wave width is below 1 // s to irradiate the laser light. The interior of the processed object is thereby locally heated due to multiphoton absorption. A melt processing area is formed inside the object to be heated. The so-called melt processing field refers to a field that is solidified after melting, which is also a field that is in a molten state, or a field that changes from a molten state to a solidified state again. It can also be referred to as a field after phase change or crystallization. Tectonic change fields. In addition, the so-called melt processing field can be said to be a field in which a single structure, an amorphous structure, and a polycrystalline structure are formed by a certain structural change to form another structure. That is to say, for example, a field in which an amorphous structure is formed by a change in a single crystal structure, a field in which a polycrystalline structure is formed by a change in a single crystal structure, Constructed sphere. When the object to be processed is a silicon single crystal structure, for example, the amorphous silicon structure may be used in the melt processing field. The upper limit 値, which is the electric field strength, is preferably 1 × 10 12 (W / cm2), for example. The pulse wave width is preferably, for example, Ins to 200 ns. The inventors have confirmed through experiments that a melt processing field is formed inside a silicon wafer. The experimental conditions are as follows. (A) Processing object: Silicon wafer (thickness 3 50 // m, outer diameter 4 inches) (B) Laser light source: semiconductor laser excitation Nd: YAG laser -14- 200539978 Wavelength: 1 0 6 4 nm Laser light site cross-sectional area: 3.141xl (T8cm2 Vibration pattern: Q-switched pulse wave repetition frequency: 100kHz Pulse wave width: 30ns Output: 20 // 〖/ Pulse wave laser light quality: TEM ... Polarization characteristics: linear polarized light ) Condensing lens magnification: 50 times N. A.: 0.55 Transmittance to laser light wavelength: 60% (D) Movement speed when the object to be processed is placed: 100mm / sec Figure 12 It is a photograph of a cross section of a part of a silicon wafer cut by laser processing under the above conditions. The silicon wafer 11 has a melt processing area 13 formed inside it. Furthermore, the melt processing formed under the above conditions The area 13 has a thickness of about 100 V m in the thickness direction. Next, the melt processing area 13 is formed by multiphoton absorption. Figure 13 illustrates the wavelength of laser light and the transmittance inside the silicon substrate. The relationship diagram. However, each reflection of the front and back ends of the silicon substrate is excluded. The composition only represents the internal transmittance. The foregoing relationships are explained for the thickness t of the silicon substrate of 50 // m, 100 // m, 200 # m, 500 # m, 1000 / zm. For example, Nd: YAG laser When the wavelength is 1 064 nm and the thickness of the silicon substrate is less than 500 // m, it is known that more than 80% of the laser light will pass through the -15-200539978 inside the silicon substrate. As shown in Figure 12, the silicon The thickness of wafer 1 1 is 3 5 0 // m, so the fusion processing area 1 3 generated by multi-photon absorption is near the center of silicon wafer 1 1, which is formed at 1 75 // m from the surface. In this case, the transmittance in this case refers to a silicon wafer with a thickness of 200 / zm. Since it is more than 90%, only a small amount of laser light is absorbed inside the silicon wafer 1 and almost passes through the silicon. This phenomenon means that instead of the laser light being absorbed inside the silicon wafer 1 1, a melt processing area 1 3 is formed inside the silicon wafer 1 1 (that is, the general Heating to form the melt processing field), but the melt processing field 1 3 is formed by multiphoton absorption. The formation of the fusion processing field produced by the absorption of sub-absorption, for example, in the lecture of the National Assembly of the Welding Society, Chapter 66 (April 2000), pages 72 to 73, "Silicone due to picosecond pulse wave laser "Processing characteristics evaluation" is described. In addition, silicon wafers use a cutting starting area formed by a melt processing field as a starting point to cause cracks in a cross-sectional direction, and the cracks reach the surface and back of the silicon wafer through the cracks. The cutoff is reached as a result. The cracks that reach the front and back of the silicon wafer may grow naturally, and there may be cases where the silicon wafer grows by applying force to the silicon wafer. Then, in the case where the growth of the silicon crystal on the surface and the back surface naturally grows from the cut-off starting region, there may be a case where the cracking system starts to grow from a molten state where the cut-off starting region is melted, and There is also a case where the fracture grows when the melt processing area forming the cut-off starting area is melted and starts to solidify again. However, in either case, the melt processing area is formed only inside the silicon wafer. As shown in FIG. 12 at the cut surface, only the melt processing area is formed inside. In this way, when the cutting starting area is formed by -16-200539978 part in the processing object through the melting process area, it is difficult to cause unnecessary breakage from falling off the cutting starting area line during cutting, so the cutting control is changed. Make it easy. (3) In the case where the reforming field is a refractive index change field, the condensing point is aggregated inside the processing object (such as glass), the electric field intensity at the condensing point is 1xl08 (W / cm2) or more, and the pulse wave width is Ins or less The conditions are irradiated with laser light. When the pulse width is made relatively short, when multi-photon absorption occurs inside the processing object, the energy generated by the multi-photon absorption will not be converted into thermal energy, and the valence of ions in the processing object will change, crystallize, or polarize. The long-term structural change will be induced to form a refractive index change field. The upper limit 値 of the electric field strength is preferably 1 × 1012 (W / cm2), for example. The pulse wave width is preferably, for example, Ins. Below lps is better. The formation of refractive index change fields caused by multiphoton absorption, such as "parts per billion" in pages 105 to 111 of the Proceedings of the 42nd Laser Thermal Processing Research Society (November 1997) The formation of light-induced structures inside the glass produced by one-second laser irradiation is documented. The above is a description of the cases (1) to (3) of the reforming area formed by multiphoton absorption. If the crystal structure of a wafer-like object to be processed or its splitting properties are considered, it will be described below. When the cutting starting area is formed, the cutting starting area can be used as a starting point, and the object to be processed can be cut with a lower level of force and with good accuracy. In other words, in the case of a substrate composed of a single crystal semiconductor with a diamond structure such as silicon crystal, the substrate is formed along the (1 1 1) plane (the first section plane) and the (1 10) plane (the second section) It is better to form the cut-off starting area in the direction of opening). In addition, in the case of a substrate composed of a group III-V compound semiconductor having a sphalerite structure such as GaAs, it is preferable to form a cutting starting region in a direction along the (11 ο) plane. In addition, in the case of a substrate having a crystal structure of a hexagonal crystal series such as sapphire (Al203), the (001) plane (c-plane) is used as the main plane and the (1120) plane (A-plane) is used. Alternatively, it is preferable to form a cutting starting area in the direction of the (1100) plane (M plane). In addition, it is formed on the substrate in a direction in which the aforementioned cut-off starting region should be formed (for example, along the (11 1) plane of the single crystal silicon substrate), or in a direction perpendicular to the direction in which the cut-off starting region should be formed. By using the positioning plane as a reference, the positioning plane can easily and accurately form the cutting starting region on the substrate along the direction in which the cutting starting region should be formed. Hereinafter, a suitable embodiment of the method for cutting an object to be processed according to the present invention will be described. 15 to 17 are cross-sectional views of a part taken along the line XV-XV of the silicon circle in FIG. 14. As shown in FIG. 14, on the surface 3 of the silicon wafer (semiconductor substrate) 11 that is the object of processing, a plurality of functional elements 15 are formed in a matrix pattern in a direction φ line and a direction perpendicular to the positioning plane 16. . The aforementioned silicon wafer 11 is cut for each functional element 15 as described below. First, as shown in FIG. 15 (a), a double-sided adhesive tape 17 is adhered to the surface 3 of the silicon wafer 1 1. The adhesive layer 17 a on the silicon wafer end of the double-sided tape 17 will reduce the adhesive force due to the irradiation of ultraviolet rays, and generate a gas at the interface with the silicon wafer 11 to cause the silicon wafer 11 to peel off by itself. The self-peeling type double-sided tape 17 is, for example, "SELFA (trade name)" of Sekisui Chemical Industry Co., Ltd. Then, as shown in Fig. 15 (b), the adhesive layer 17 on the opposite side of the silicon wafer 1 1 with the double-sided tape 18- 200539978 with 17 1 is attached with a glass shape maintaining plate (shape Maintenance body) 1 8. In this way, since the shape maintaining plate 8 is mounted on the surface 3 of the silicon wafer 11 on which the functional element 15 is formed, the functional element 15 can be protected. Next, as shown in FIG. 15 (c), the sand wafer 11 is transferred to the honing apparatus 50 in a state where the shape maintaining plate 18 is mounted on the surface 3, and the processing table 5 in the honing apparatus 50 is transferred. 1, the silicon wafer 1 1 with the back 2 1 facing upward, and then the shape maintaining plate 18 is fixed. Then, the back surface of the silicon wafer 11 is rotated by a φ-rotating grindstone 5 2 to perform plane cutting. For example, the silicon wafer 1 1 having a thickness of 3 5 0 // m is reduced to a thickness of 100 μm. By using the aforementioned shape maintaining plate 18, the surface 3 of the silicon wafer 11 and the functional elements 15 formed on the surface 3 are protected, and the silicon wafer 11 can be prevented from being deformed and the silicon wafer 11 can be thinned. . Next, as shown in FIG. 16 (a), the silicon wafer 11 is transported to the laser processing apparatus 60 with the shape maintaining plate 18 mounted on the surface 3, and is processed on the processing table 61 of the laser processing apparatus 60. With the back surface 21 of the silicon wafer 11 facing upward, the shape maintaining plate 18 is fixed. Then, the predetermined cutting line 5 is set in a grid pattern between the adjacent functional elements 15 and 15 (refer to the two-point locking line in FIG. 14), and the back surface 21 is used as the laser light incident surface. The light-condensing point P is polymerized inside the silicon wafer 1 1, and the laser light L is irradiated under the condition that multi-photon absorption is generated, and the light-condensing point P is moved along a predetermined cutting line 5 by moving the processing table 6 1 Make a relative move. As a result, as shown in FIG. 16 (b), the silicon wafer 11 is formed along the predetermined cutting line 5 to form a cutting starting region 8 generated by the field melting * process 13. In this way, by using the back surface 2 1 of the silicon wafer 11-as the laser light incident surface ', for example, even if there is a part reflecting the laser light L in the functional element 1 5, it can still be -19 inside the silicon wafer 1 1 -200539978 The cut-off point area 8 is definitely formed. Next, "the silicon wafer 11 with the shape maintaining plate 18 mounted thereon is removed from the processing table 61", as shown in Fig. 16 (0), using a tape sticking machine (not shown), The back surface 2 1 is attached with an extension tape (expandable film) 1 9. _ GuangMu tape 1 9 The outer peripheral part is adhered to a ring-shaped tape fixing frame 2 2 ′ and fixed to this fixing frame 2 2. As shown in FIG. 17 (a), the sand wafer on which the extension tape 19 is attached on the back surface 21 and the shape maintaining plate 18 is mounted on the surface 3 is conveyed to the film. The expansion device 70 is configured to hold the adhesive tape fixing frame 22 with a ring-shaped receiving element 71 and a ring-shaped pressing element 72 to mount the sand wafer 11 to the film expansion device 70. In this state, the shape The ultraviolet rays are irradiated to the 8 ends of the plate 18, and the double-sided tape is removed from the surface 3 of the silicon wafer 藉 by reducing the adhesive force of the adhesive layer 17a and generating gas at the interface of the silicon wafer 11. 7 and the shape maintaining plate 丨 8. Then, as shown in FIG. 17 (b), the cylindrical shape arranged inside the receiving element 7 1 is formed. The pressing element 73 rises from the lower end of the expansion tape 19, and as shown in FIG. 17 (c), φ cuts the sand wafer 11 by cutting the starting point area 8 as a starting point by expanding the expansion tape 19 At the same time, the wafers 23 that are cut are separated from each other. As a result, each wafer 23 can be easily and accurately retrieved. In the method for cutting a processing object described above, the silicon wafer i The back surface 2 1 serves as the laser light incident surface and is formed along the predetermined cutting line 5 inside the sand wafer 1 1 to form a cut-off starting area 8 generated by the melt processing area 1 3 until the silicon wafer is reached. 1 The back surface of 1 1 2 until the extension tape 19 is attached,-the shape maintaining plate 1 8 is mounted on the surface 3 of the sand wafer 1 1. With this shape maintaining plate 1 8, the silicon wafer 1 1 can be reliably prevented The deformation is formed by cutting -20-200539978. • The silicon wafer 1 1 in the spot area 8 can be easily processed. Then, by removing the shape maintaining plate 18 from the surface 3 of the silicon wafer 11, The method of expanding the expansion tape 19 is to generate the cutting starting area 8 as the starting point and the silicon wafer 11 is cut. The plurality of wafers are separated from each other. As a result, the silicon wafer 11 having the cut-off starting area 8 is formed into a plurality of wafers 23 because the deformation is surely prevented, so that it is possible to prevent the occurrence of cutting. Improper phenomena such as chipping and cracking occur on the plurality of wafers 23. In addition, the formation of the cutting starting area 8 is performed on the laser processing device 60. The shape maintaining plate 18 is removed and the wafers 23 are removed. Since the separation is performed on the thin film expansion device 70, the configuration of each device 60, 70 can be simplified. Then, the silicon wafer 11 of the thin film expansion device 70 is transferred from the laser processing device 60, although the silicon crystal The cut-off starting area 8 is formed inside the circle 11, but since the shape maintaining plate 18 is mounted on the surface 3 of the silicon wafer 11, the silicon wafer 1 can be prevented from being cut off from the starting-up area 8 as a starting point during transportation. 1Inadvertently cut off. Next, the configuration of the thin film expansion device 70 described above will be described. As shown in Figs. 18 to 20, the thin film expansion device 70 includes a receiving element 7 and a pushing element 72, a main body portion 74 provided with a pressing element 73, and a support base 75 provided in a row on the main body portion 74. A cover 79 capable of being opened and closed is attached to the main body portion 74, and an ultraviolet lamp 76 is attached to the back of the cover 79. In addition, a swingable arm 78 having a suction pad 77 fixed to the front end is attached to the main body portion 74. Next, a method of using the thin film expansion device 70 configured as described above will be described. First, as shown in FIG. 18 (a), the silicon wafer 11 is mounted on the thin film expansion device -21-200539978 sheet device 70 by the receiving element 71 and the pushing element 72 with the lid 79 opened. Then, as shown in Fig. 18 (b), the lid body 79 is closed, and in this state, ultraviolet rays are irradiated from the 18 ends of the shape maintaining plate 18 by the ultraviolet lamp 75. Thereby, the double-sided tape 17 and the shape maintaining plate 18 can be detached from the surface 3 of the silicon wafer 11. Next, as shown in FIG. 19 (U), the cover 79 is opened, and in this state, the arm 78 is swung to move the suction pad 77 on the shape maintaining plate 18, and the shape maintaining plate 1 is suctioned by the suction pad 7 7 8. Thereafter, as shown in FIG. 19 (b), the arm 78 is moved to move the double-sided tape 17 and the shape maintaining plate 18 on the mounting table 75. Then, as shown in FIG. 20, the pressing element 7 3 is raised from the lower end of the expansion tape 19, and by expanding the expansion tape 19, the cut-off area is used as a starting point, and the silicon wafer 11 is cut off. The resulting wafers are generated separately from each other. The present invention is not limited to the foregoing embodiments. For example, in the above-mentioned embodiment, although the multi-photon absorption may be generated inside the processing object 1 to form the reforming field 7, there may be a case where the multi-photon absorption is equivalent to the multi-photon absorption in the processing object 1. In the case of reforming field 7 due to light absorption. In addition, in the aforementioned embodiment, by expanding the expansion tape 19, the silicon wafer 11 having the starting point region 8 as a starting point is cut, and the wafers 23 generated by the cutting are allowed to pass to each other. In the case of separation, the present invention is not limited to this. For example, in a state where the shape maintaining plate 18 is mounted on the surface 3, a thermal stress may be applied to the silicon wafer 11 formed on the cutting starting area 8 from the back surface 2 1 end, or the like. Before the expansion tape 19, the silicon wafer Π ° is cut with the starting point area 8 as a starting point. In addition, after the cutting starting area 8 is formed inside the silicon wafer 1 1 '-22- 200539978 back side of the wafer 11 21 Before attaching the expansion tape 19, honing the back surface 2 1 of the sand wafer 1 with the shape dimension plate 18 mounted on the surface 3, for example, silicon with a thickness of 1 00 # m The wafer 11 is further thinned to a thickness of 50 / Z m to 2 5 / zm. In this case, the surface 3 of the sand wafer 11 can also be protected, and the deformation of the silicon wafer 11 can be continuously prevented, and the thickness of the silicon wafer 11 can be further reduced. In addition, in the above-mentioned embodiment, although the shape maintaining plate 18 is made of glass, the shape maintaining plate 18 may be rigid as long as it has a degree of protection against deformation of the mounted silicon wafer 11 (for example, it may be Made of resin such as acrylic resin). However, as in the aforementioned embodiment, the shape maintaining plate 18 made of glass is mounted on the surface 3 of the sand wafer 11 through the adhesive layer 17 a. On the other hand, as long as it is from the shape maintaining plate 18 side Irradiation of ultraviolet rays to the adhesive layer 17a reduces the adhesive force of the adhesive layer 17a, and when the shape maintaining plate 18 is removed from the surface 3 of the silicon wafer π, it is easy to perform the shape of the surface 3 of the silicon wafer 丄 i Installation and removal of the maintenance plate 18. In addition, in order to mount the shape-maintaining plate 18 on the surface 3 of the silicon wafer 11 and use an adhesive layer for intervening the same, an object whose adhesive force is lowered by irradiation or heating of electromagnetic waves other than ultraviolet rays may be used. Therefore, by irradiating the adhesive layer with electromagnetic waves or heating the adhesive layer, the adhesive force of the adhesive layer is reduced, and the shape maintaining plate can be easily removed from the surface 3 of the diced wafer 1 1. 18. In the above embodiment, in the case of the shape maintaining system shape maintaining plate 18, the shape maintaining body may be an object in which a plurality of protective films are adhered to each other. In this case, as shown in FIG. 21 (a), after the protective film 25 is adhered to the surface 3 of the silicon wafer 11, on the processing table 5 1 of the cutting device 50, Xi Xijing-23- 200539978 round 1 The rear surface 2 of 1 is directed upward, and the silicon wafer 11 is fixed. The silicon wafer 11 is thinned by turning the vermiculite 5 2 on the rear surface 2 1 of the silicon wafer 1 1 to make the silicon wafer 1 1 thinner. Next, as shown in FIG. 21 (b), the silicon wafer 1 1 is fixed on the adsorption stage 81 of the tape holder 80 with the surface 3 of the silicon wafer 11 facing upward, and the silicon wafer 11 is fixed on the protective film 25. Then, one or more protective films 25 are further stuck. After that, a plurality of protective films 25 having a rigidity capable of preventing the silicon wafer 11 from being deformed by being adhered to each other are used as a shape maintaining body, and the same manufacturing process as that of the aforementioned embodiment is performed. The surface 3 of the silicon wafer 1 1 is irradiated with electromagnetic waves (such as ultraviolet rays) that can easily peel off the protective film 25. After the plurality of protective films 25 are adhered to each other, as long as the protective film 25 is bonded to the silicon wafer in the film expansion device 70 It can be performed at any time after the surface 3 of 1 is peeled off from the plurality of protective films 25. When the protective film 25 is peeled off one by one, electromagnetic waves (such as ultraviolet rays) may be irradiated at the timing when the protective films 25 are peeled off. In addition, the shape maintaining body may be an object in which the protective film 25 and the shape maintaining plate 18 are adhered to the surface 3 of the sand wafer 1 1. In this case φ ', as shown in FIG. 2 2 (a), the surface 3 of the silicon wafer 1 1 is pasted with the protective film 2 5, and then the silicon wafer 1 is placed on the processing table 5 1 of the cutting device 50 0. The back surface 2 of 1 is fixed upward, and the silicon wafer 1 1 is fixed upward. The back surface 2 1 of the silicon wafer 11 is rotated by vermiculite 5 2 to perform planar cutting to reduce the thickness of the silicon wafer. Next, as shown in FIG. 22 (b), on the adsorption table 81 of the tape holder 80, the surface 3 of the wafer 11 is directed upward, and the sand wafer 11 is fixed, and then the protective film 25 has been pasted. Attach the shape retention plate-1 to 8. Thereafter, the protective film 25 and the shape-maintaining plate 18 are used as shape-retaining bodies, and the same processes as those in the previous embodiment are performed. In addition, the irradiation of ultraviolet rays from the silicon wafer 1 1-24 to 200539978 on the surface 3 to easily peel off the protective film 25 and the shape maintaining plate 18 is after the shape maintaining plate 18 is adhered to the protective film 25 as long as In the thin film expansion device 70, the protective film 25 and the shape maintaining plate 18 can be peeled off from the surface 3 of the silicon wafer 1 1 at any time (industrial possibility). According to the present invention, The processing of the object to be processed where the starting point region is formed is facilitated, and it is possible to prevent unsuitable phenomena such as chipping and cracking caused by cutting a plurality of parts of the processing object by cutting the starting point region as a starting point. [Brief description of the drawings] Fig. 1 is a plan view of a processing object to be laser-processed according to the laser processing method of this embodiment. Fig. 2 is a sectional view taken along the line II-II of the object to be processed shown in Fig. 1. Fig. 3 is a plan view of an object to be processed after laser processing according to the laser processing method of this embodiment. Fig. 4 is a sectional view taken along the line IV-IV of the object to be processed shown in Fig. 3; Fig. 5 is a sectional view taken along the line V-V of the object to be processed shown in Fig. 3. Fig. 6 is a plan view of an object to be processed which has been cut by the laser processing method of this embodiment. Fig. 7 is a diagram illustrating the relationship between the electric field intensity and the size of the crack spot in the laser processing method of this embodiment. FIG. 8 is a cross-sectional view of the object to be processed in the first process of -25-200539978 in the laser processing method of this embodiment. Fig. 9 is a cross-sectional view of a first object to be processed in the laser processing method according to this embodiment. Fig. 10 is a cross-sectional view of an object to be processed in the laser processing method of this embodiment. Fig. 11 is a sectional view of an object to be processed in the laser processing method of this embodiment. FIG. 12 is a photographic view illustrating a cross section of a part of a silicon wafer with a limb P cut by laser processing of this embodiment. Figure 13 shows the relationship between the wavelength of laser processing light and the transmittance inside the silicon crystal substrate in the present embodiment. Figure 14 shows the silicon cut into the processing object in this embodiment. Plan view of the wafer. Fig. 15 is a schematic diagram for explaining the processing object of this embodiment. (A) is a state where a silicon wafer is bonded with a double-sided tape, and a state where the tape is attached to a shape maintaining plate, and (c) is a silicon wafer. The state of cutting. Figure 16 is a schematic diagram for explaining the processing object of this embodiment. (A) is a state where the silicon wafer is being irradiated with laser light, and a state where the starting point of the wafer is cut off is formed. (C) is a silicon crystal expansion tape. status. Figure 17 is a schematic diagram for explaining the processing object of this embodiment. U) It is a state where the ultraviolet light is irradiated in the thin film expansion device. The pressing element is raised in the thin film expansion device. The wafers in the expansion device are separated from each other. status. In the 2nd process, in the 3rd process, in the 4th process, the method is cut, and in the method, the thunder curve. In the method, the object cutting method is (b) a double-sided wafer cutting method, (b) a state where an object cutting method is bonded to a silicon circle, and (b) (0) on a thin film. -26- 200539978 Figure 18 is a perspective view of the thin film expansion device of the present embodiment, (a) is a state in which a silicon wafer is mounted, and (b) is a state in which ultraviolet rays are irradiated. FIG. 19 is a view of this embodiment A perspective view of the thin film expansion device is (a) a state in which the suction pad is moved to the shape maintaining plate, and (b) a state in which the double-sided tape and the shape maintaining plate are moved to the stage. The oblique view of the thin film expansion device of the embodiment is a state in which the pressing element is raised. Fig. 21 is a schematic diagram for explaining a cutting method of the processing object of the embodiment φ and a modification example thereof, U) is a silicon crystal (B) is a state where the protective film is bonded to the protective film. Fig. 22 is a schematic diagram for explaining a modification example of the cutting method of the processing object in this embodiment, (a) is a state in which a silicon wafer is subjected to cutting, and (b) a shape maintaining plate is bonded to a protective film. Of the state. [Description of main component symbols] 1 ... Object to be processed 3 ... Surface ^ 5 ... Scheduled cutting line 7 ... Reforming area 8 ... Cutting starting area Π ... Silicon wafer (semiconductor substrate) 13 ... Melt processing area 15 ... Functional components '18… Shape retention plate (Shape retention body) • 19… Expansion tape (expandable film) 21… Back (Laser light incident side) -27- 200539978 23… Chip 25… Protective film 60… Laser processing device 70… Film expansion device L ·· • Laser light P · · • Condensing point
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