201236795 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種雷射切割（laser scribe)方法，尤 有關於一種將脈衝（p 1 u s e )雷射光照射於脆性材料基板並 進行切割之雷射切割方法。此外，本發明係關於一種雷射 加工裝置’尤有關於一種將脈衝雷射光照射於脆性材料基 板’並沿著切斷預定線將脆性材料基板予以切割的雷射加 工襞置。 【先前技術】 發光二極體（diode)等之發光元件，係藉由將氮化物半 導體疊層在藍寶石（sapphire)基板上而形成。在由此種藍 寶石基板等所構成的半導體裝置中，係藉由切斷預定線而 劃分形成有複數個發光二極體等的元件。再者，為了沿著 切斷預定線將半導體裝置切斷，乃採用雷射切割方法。 雷射切割方法係將雷射光照射於基板等之工件（w 0 r k ) 而進行切割的方法，例如揭示於專利文獻1。在此專利文 獻1所示的方法中’係將雷射光之聚光點的位置調整於基 板背面，且沿著切斷預定線來進行雷射光掃描。之後，使 雷射光的聚光點朝基板的厚度方向移動，且同樣沿著切斷 預定線進行雷射光掃描。 此外，在專利文獻2中，係揭示一種將脈衝雷射光照 射於矽基板或玻璃基板等而在基板内部形成改質區域，且 進行切割的方法。在此專利文獻2所示的方法中，係將脈 衝雷射光的聚光點調整成位於基板内部。再者，在脈衝雷 323755 4 201236795 =光’、射於基板之後，不改變聚光點的位置下朝橫方向杯 田# = “、、射下一個脈衝雷射光。藉由重複此種雷射照射’ 而著切斷預定線週期性地形成從基板之背面側朝向表命 侧傾斜延伸的複數個改質區域。 [先前技術文獻] [專利文獻] [專利文獻1]日本特開2007-21557號公報 [專利文獻2]日本特開2007-167875號公報 【發明内容】 [發明所欲解決之課題] 在此，尤其在將半導體疊層於藍寶石基板上而形成發 光二極體時，為了不使做為最終製品之發光二極體的泠質 劣化，藉由雷射照射形成的改質區域（以下亦稱雷射加;^浪 跡或簡稱加工痕跡）係以盡量較少為佳，此外，為了不損及 端面強度等的強度，改質區域係以較少為佳。另一方面， 改質區域較少時，在切割後的切斷步驟中，需要更大的切 斷力，而會有依狀況不同而無法切斷的情形。 因此，在雷射切割中，需要藉由在後序步驟中切割多 易而且形成較少（較窄）的改質區域來進行切割。為了達成 此種目的，可考慮沿著切斷預定線而週期性地形成朝芙板 之厚度方向延伸之線狀的複數個改質 區域（以下稱為線狀 加工痕跡）。此種線狀加工痕跡係可藉由專利文獻 示的方法來形成。 及2所 然而，在以專利文獻1所示之雷射切割方法來形成線 323755 5 201236795 狀加工痕跡時，需將雷射光之聚光點設置於複數個位置， 且依該複數個位置沿著切斷線進行雷射光掃描。在此種方 法中，處理會變得繁雜，而且裝置構成也會變得複雜而且 高價。 此外，在專利文獻2所示的方法中，雖不需變更聚& 點的位置，但完全未揭示有射束（beam)強度等之雷射照射 條件。因此，即使是該相關業者，也無法參照該專利文獻 2而穩定地形成線狀加工痕跡。因此，會有在基板表面咬 背面形成廣泛面積之面狀而非線狀的改質區域，而且也备 有反而造成線狀加工痕跡變少，而在切斷步驟中需要較大 切斷力的情形。再者，在该專利文獻2中，由於係以1脈 衝形成300ym的加工痕跡，因此在厚度為1〇〇ym左右的 基板無法形成線狀加工痕跡。 本發明之目的係在於當藉由雷射光將藍寶石基板等 脆性材料基板崎_時，簡單的裝置構成即 當寬闊的改質區域。 X通 [解決課題之手段] 第1發明之雷射切割方 材料基板並沿著切斷預定線進，脈衝雷射光照射於脆性 步驟與第2步驟。帛1步驟係:切割’該方法係具備第1 料基板，iiW切咖定線=脈^射絲射於脆性材 料基板之表面及背©之内部 1掃痴’且在遠離脆性材 層。第2步驟係將經調整射=成沿著切斷預定線的改質 料基板，並且固定雷射光之隹度之雷射光照射於脆性材 ’、、、點位置並沿著切斷預定線進 323755 6 201236795 •行掃描，且沿著切斷預定線而週期性地形成以改質層為起 點而進展至未到達脆性材料基板之表面之深度的複數個線 狀加工痕跡。 在此，本案發明人係開發一種以簡單的裝置構成即可 形成適當寬闊之改質區域的雷射切割方法，且已提出申請 (曰本特願2010-193220)。在此雷射切割方法中，係從脆 性材料基板之背面朝向表面形成預定長度的線狀加工痕 跡’再者’沿著切斷預定線而週期性地形成該線狀加工痕 跡。 然而’在例如發光二極體中，係在藍寶石基板上疊層 半導體而形成元件。再者，在將前案之雷射切割方法應用 於此種發光二極體時，為了不會對元件造成損害’係從未 形成有元件之面（表面）照射雷射光。於是，在前案的方法 中，即會在形成有元件的面（背面），形成成為線狀加工痕 跡之起點的改質區域。此時，形成於基板之一面（背面）的 元件，會有受到損害的可能。 北因此，在本發明中，係在遠離脆性材料基板之表面及 月面的内部形成改質層，且以該基板内部之改質層為起點 形成線狀加工痕跡。 在此，由於可在較少的改質區域形成切割線，因此可 =最終，品之品質及強度劣化。此外，在後序步驟的切 可較容易地切斷。此外，由於改質層係形成於基板内 而線狀加卫痕跡則係以該改質層為基點而進展，因此 在基板之面形成有元件之情形下，亦可抑制對元件 323755 7 201236795 造成損傷。 第2發明之雷射切割方法係如第1發明之雷射切割方 法，其中在第2步驟中，脈衝雷射光之射束強度係調整成 在改質層超過8.8xl012W/m2,而在到達表面為止之基板内部 則低於 8. 8xl012W/m2。 在此，由於在基板内部之改質層中脈衝雷射光之射束 強度超過臨限值（8. 8x1012W/m2)，因此當進行脈衝雷射光之 掃描時，雷射加工痕跡即以改質層為起點而朝向表面往斜 >方行進。再者，在到達表面前的基板内部中，由於射束 強度係低於臨限值（8. 8x1012W/m2)，因此在低於臨限值的時 間點’線狀加工痕跡朝上方的進展會停止，而再度於改質 廣形成雷射加工痕跡。藉由重複進行以上的步驟，即沿著 切斷預定線而週期性地形成從改質層延伸至未到達表面之 深度的線狀加工痕跡。 第3發明之雷射切割方法，係如第2發明之雷射切割 方法’其中，在第2步驟中，係以在脆性材料基板中每單 位體積吸收之能量成為1. 5x101GJ/m3以下之方式調整雷射 將射及掃描條件。 ^在雷射照射及掃描中，當在第2發明之條件下而且每 參位體積吸收之能量超過2. GxirW時，即形成鄰接之 2狀加工痕跡相連之面狀加工痕跡，而無法縮小改質區 因此，在此係將雷射照射及掃描條件調整成每單位體 積°及收之能量成為2.0xl01()J/m3以下。 第4發明之雷射切割方法，係如第i至第3發明之雷 323755 8 201236795 射切割方法，其中脆性材料係為藍寶石。 第5發明之雷射切割方法係將脈衝 材料基板錢行切割，該方法聽訂列”於跪性 第、1步驟：將雷射光照射於脆性材料基板並且 著切斷預定線進行掃描，以形成朝脆性材料: 板之厚度方向進展之線狀雷射加工痕跡。 ^ 第2步驟··當線狀雷射加工痕跡在基板厚度 至預疋位置時’停止雷射光對於脆性材料基板的照射。 狀能^ ^停止雜光狀驗㈣絲之照射的 了^賴1使雷射光之照射位置朝掃描方向移動 =日、’再度開始雷射光對於脆性材料基板的照射。 照射及:二執行雷射光對於脆性材料基板的 著切斷射之再度開始的各處理，沿 跡。疋、·、而週期性地形成複數個線狀之雷射加工痕 料基定:：衝雷射光照射於脆性材 度方向延伸之線狀加卫^知描。藉此’形成朝基板厚 板厚度方向中進展至預=位署再者，在線狀加工痕跡於基 照射。因此置時’停止雷射光對於基板的 繼續進行。再者，於的進展亦停止。另外’掃描則 光之照射位置朝掃描之照射暫時停止之後，在雷射 開始雷射光對於基板的預定距離的時間點，再度 痕跡。藉由重複以上之雷射光對於基板的照射、停止，而 323755 9 201236795 沿著切斷預定線週期性地形成複數個線狀加工痕跡。 如前所述，在例如發光二極體中，係於藍寶石基板的 背面疊層半導體而形成有元件。因此，在基板背面形成改 質區域並不理想。另一方面，在基板之表面未形成有元件 時，線狀加工痕跡係以形成至表面附近，在後序步驟中進 行切斷時’較能以較少的力而易於將基板切斷。 然而’由本案發明人所提之前案（日本特願〇_ 193220)的雷射切割方法中，由於係以雷射照射條件來決定 線狀加工痕跡之進展的程度（長度），因此難以精確度良好 地管理線狀加工痕跡的長度而使線狀加工痕跡到達表面附 近。 因此，在本發明中，係在線狀加工痕跡進展至預定位 置的時間點，暫時停止雷射光對於基板的照射，且停止線 狀加工痕跡的進展。因此，易於使線狀加工痕跡進展至所 希望的位置並使之停止，不需嚴格管理雷射照射條件，即 可將線狀加工痕跡形成至脆性材料基板的表面附近。 第6發明之雷射切割方法係如第5發明之雷射切割方 法，其中，第3步驟係在脈衝雷射光之照射位置移動至未 與既已形成之雷射加工痕跡重疊之位置時執行。 於停止雷射光之後再度開始照射時，當既已形成之雷 射加工痕跡與新照射的雷射光重疊時，會有既已形成之線 狀加工痕跡進一步進展而到連基板表面，而形成面狀而非 線狀加工痕跡的情形。此種面狀加工痕跡，由於改質區域 極廣，因此並不理想。 323755 10 201236795 因此’在此第6發明中’係在雷射照射位置移動至不 與既已形成之雷射加工痕跡重疊之位置的時間點，再度開 始雷射光對於基板的照射。藉此，即可防止形成面狀之加 工痕跡’而確實地形成線狀雷射加工痕跡。 第7發明之雷射切割方法係如第5或第6發明之雷射 切割方法’其中，脈衝雷射光係以線狀雷射加工痕跡之起 點成為脆性材料基板之背面之方式設定照射條件。 在此，可易於形成從脆性材料基板之背面延伸至表面 附近的線狀加工痕跡，且在序後步驟中，可更容易地切斷 基板。 第8發明之雷射切割方法係如第5或第6發明之雷射 切割方法’其中雷射光係以線狀雷射加工痕跡之起點成為 每·離脆性材料基板之背面及表面之基板内部之方式設定雷 射照射條件。 在此’係以遠離脆性材料基板之表面及背面之内部為 起點形成線狀加工痕跡’因此線狀加工痕跡係從遠離基板 者面之内部延伸至表面側而形成。因此，在基板背面形成 有元件時，可抑制對元件造成的損害。 第9發明之雷射切割方法係如第5至第8發明中任一 發明之雷射切割方法，其中，雷射光係調整成射束強度在 跪性材料基板中之線狀加工痕跡形成預定區域超過8 8χ WW。 在此，於成為線狀加工痕跡之起點的位置，由於雷射 光之射束強度超過臨限值（8.8xl012W/m2)，因此當進行雷射 323755 11 201236795 光掃描時，雷射加工痕跡即從起點朝向表面進展。再者， 由於在預定的時間點暫時停止雷射光對於基板的照射因 此線狀加工痕跡的進展會在所希望的位置停止。之後， 度開始雷射光的照射，且再度從起點形成線狀加工痕跡。 藉由重複以上步驟，沿著切斷預定線而週期性地形成複數 個線狀加工痕跡。 第10發明之雷射切割方法係如第9發明之雷射切割方 法，其中，雷射光係以在脆性材料基板中每單位體積吸收 之能量成為2. Gxin/m3以下之方式調整照射及掃描條件。 在雷射照射及掃财，當在第8伽之條件下而且 單位體積吸收之能量超過2· ，即形成鄰接之 線狀加工痕跡相連之面狀加工痕跡’而無法縮小改質區 域。因此，在此係將雷射闕簡描條件難成每單位體 積吸收之能量成為2. 〇xl〇〖°J/m3以下。 第發月之雷射切割方法係如第5發 中之任-發明的雷射_方法，^ 4 U赞月 °】万去其中，脆性材料係為藍寶 第12發明之雷射加工梦罟作脸带 , . # 、置仏將〶射光照射於脆性材 枓基板紅者切斷預定線將脆性材料基板進行切割，該 裝置係具備.雷射光線振盪單元 、正“ 益早疋傳达先學系統、聚光透 鏡（lens)、平 σ (table)、移動批也I„ 砂動控制部、及加工控制部。 射光線振盪單元係包含雷射弁續 由耵元綠振盪器、及調整雷射光 之射束強度的雷射控制部 田对九綠 統係用以將從雷射光線振盪單 号达尤子糸 盈早70射出之雷射光引導至預定 323755 12 201236795 方！^聚㈣鏡制錢來自傳送光學系㈣雷射光聚光 之透鏡。平线可在相對於來自聚光透鏡之 ’ :的面内相對移動，用以載置供來自聚光透;=; 生材料基板。移動控制部係使來自聚光透鏡之雷身i 動控制ΓΓ移動。加工控制部係控制雷射控制部及移 台:脆性材料而週期性地形成朝載置於平 痕跡。此外二控 第力月b。第1功能係將雷射光昭# 固定焦點位置並沿著切斷預定線進' ==並且 材料基板之厚度方向進展之線狀雷二;场，性 係線狀雷射加工痕跡在基板厚度方向進展至預定位置^ 分止雷射光對於脆性材料基板的照射: =::=r_狀態下，== 於脆性材料基板的照射。::距:二:度開始雷射光對 線狀雷射加μ跡斷預疋線而週期性地形成複數個 工痕裝置，與前述相同地，易於使線狀加 射昭义射侔#f的位置並使之停止，不需嚴格管理雷 t面=件’即可將線狀加工痕跡形成至脆性材料基板的 [發明之功效] 在如上所述的本發明中，係可在將藍寶石基板等之脆 323755 13 201236795 性材料基板進行_時，以簡單的裝置構成，形成適當寬 闊的改質區域n於基板形成有元件時，可抑制對元 件造成的損害。再者，可易於管理線狀雷射加工痕跡的進 【實施方式】 I :加工對象 第1圖係為應用本發明之—實_態之雷射切割方法 之半導體晶圓之-例。帛i圖所示之晶圓i係在藍寶石基 板2上4層錢化解導體卿成者，福由分割預定線 4而劃分形成有複數個發光二極體等的發光元件3。 II :雷射加工裝置 第2圖係為顯示用以實施本發明之一實施形態之加工 方法之雷射加工裝置5之概略構成者。雷射加工裝置5係 具有：包括雷射光線振盛器6a及雷射控制器肋之脈衝雷 射光線振盪單元6;包括用以將雷射光引導至預定方向之 複數個反射鏡（mirror)的傳送光學系統7 ;及用以使來自 傳送光學系統7的雷射光聚光之聚光透鏡8。從脈衝雷射 光線振鮮元6㈣有經控制射束強度等之照射條件的脈 衝雷射光（以下簡稱為雷射光）。半導體晶圓丨係載置於平 台9。平台9係藉由驅動控制部2〇來驅動控制，且可在水 平面内移動。亦即，載置於平台9之半導體晶s丨與從聚 光透鏡8照射之雷射光線係可在水平面内相對移動。此 外’聚光透鏡8與魅有晶圓丨的平台9，係可相對地在 上下方向移動。雷射控制器6b及驅動控制部2〇係藉由加 323755 14 201236795 工控制部21所控制。 加工控制部21係以微電腦（micro computer)所構成， 用以控制雷射控制器6b及驅動控制部20。 ΙΠ :雷射切割方法（1) 使用以上所述之雷射加工裝置5之第丨雷射切割方法 係如下列所述。 [第1步驟] 首先’在脈衝雷射光線振盛單元6中，控制雷射光之 輸出功率（power)等之加工條件。再者，將該雷射光照射至 藍寶石基板2，且在遠離藍寶石基板2之表面及背面的内 部形成改質區4。料’雷射光係為穿透絲的穿透型雷 射。再者，將該雷射光沿著切斷預定線掃描。藉此，在基 板内部’形成沿著切斷預定線的改質層。 第3A圖及第3B圖係顯示形成於基板内部之改質層的 具體例。任一例均係使用厚度為330 之藍寶石基板^ 試料。 ° [例1] 第3A圖之雷射照射條件如下。 波長：1064nm。 脈衝寬度：20ps。 脈衝能量：1.4# J。 掃描速度：500mm/s。 雷射照射方向：從表面。 焦點位置：z = 100 /z m。 323755 15 201236795 在此例1中， 有改質層Ml。 係在基板之厚度方㈣大致中間部形成 [例2] 第3B圖之雷射照射條件係如下。 波長：1064nm。 脈衝寬度：20ps。 脈衝能量：1. 0// J。 掃描速度：50mm/s。 雷射照射方向：從表面。 焦點位置· z = 140 y m。 在此例2中， 質層M2。 係在基板㈣接”叫區域形成有改 ' 、。丁 J展點位詈& 重複頻率、輸丨、及_速度，但可 卜’雖變更了 來變更形成有改質層的位置（深度）。 由變更焦點位置 [第2步驟] 接著’控制雷射光之輸出功率 述），且將該雷射光照射至藍寶石美板Π工條件（詳如後 射光之焦點(在此係與「聚:點」二：在固定雷 沿著切斷預定線㈣料相對移料 3的狀態下， 基板内部之顯微鏡相片之第4圖所八 坷描。藉此，如 數個線狀雷射加工痕跡1〇 g卩、VL#不做為改質區域之複 形成。如此一來’半導體晶圓1即沿著切斷二而週期性地 另外，在第4圖中雖係顯示以基板背面為起二線= 323755 16 201236795201236795 VI. Description of the Invention: [Technical Field] The present invention relates to a laser scribe method, and more particularly to a ray that irradiates a pulsed (p1 use) laser light onto a substrate of a brittle material and performs cutting Shoot cutting method. Further, the present invention relates to a laser processing apparatus </ RTI> which is particularly directed to a laser processing apparatus for irradiating a pulsed laser light onto a brittle material substrate and cutting the brittle material substrate along a line to cut. [Prior Art] A light-emitting element such as a light-emitting diode is formed by laminating a nitride semiconductor on a sapphire substrate. In a semiconductor device including such a sapphire substrate or the like, an element such as a plurality of light-emitting diodes is formed by cutting a predetermined line. Further, in order to cut the semiconductor device along the line to cut, a laser cutting method is employed. The laser cutting method is a method of cutting laser light onto a workpiece (w 0 r k ) such as a substrate, and is disclosed, for example, in Patent Document 1. In the method shown in Patent Document 1, the position of the light collecting spot of the laser light is adjusted to the back surface of the substrate, and the laser scanning is performed along the line to cut. Thereafter, the condensed spot of the laser light is moved toward the thickness direction of the substrate, and the laser beam scanning is also performed along the line to cut. Further, Patent Document 2 discloses a method of forming a modified region inside a substrate by irradiating a pulsed laser light onto a ruthenium substrate or a glass substrate or the like, and performing dicing. In the method disclosed in Patent Document 2, the condensing point of the pulsed laser light is adjusted to be located inside the substrate. Furthermore, after the pulse Ray 323755 4 201236795 = light ', after the substrate is shot, the position of the light-converging point is not changed, and the field is facing the horizontal direction # = ",, a pulse of laser light is shot. By repeating such a laser The plurality of modified regions which are obliquely extended from the back side of the substrate toward the front side of the substrate are formed periodically. [Patent Document] [Patent Document 1] Japanese Patent Laid-Open No. 2007-21557 [Problem to be Solved by the Invention] Here, in particular, when a semiconductor is laminated on a sapphire substrate to form a light-emitting diode, In order to deteriorate the enamel of the light-emitting diode as the final product, the modified region formed by the laser irradiation (hereinafter also referred to as "laser plus; ^ wave or short processing mark" is preferably as small as possible, and In order not to damage the strength of the end face strength, etc., the modified region is preferably less. On the other hand, when the modified region is small, a larger cutting force is required in the cutting step after cutting, and Can not be cut depending on the situation Therefore, in laser cutting, it is necessary to perform cutting by cutting in the subsequent step and forming a less (narrower) modified region. To achieve this, it is considered to be scheduled along the cut. A plurality of linear modified regions (hereinafter referred to as linear processing marks) extending linearly in the thickness direction of the slab are periodically formed on the line. Such linear processing marks can be formed by a method described in the patent document. And 2, however, when the line 323755 5 201236795 is processed by the laser cutting method shown in Patent Document 1, the spot of the laser light needs to be set at a plurality of positions, and along the plurality of positions The cutting line performs laser scanning. In this method, the processing becomes complicated, and the device configuration becomes complicated and expensive. Further, in the method disclosed in Patent Document 2, it is not necessary to change the poly & Since the position of the point is not disclosed, the laser irradiation condition such as the beam intensity is not disclosed at all. Therefore, even in the related art, the linear processing mark cannot be stably formed by referring to Patent Document 2. Therefore, there is a modified region in which a wide area is formed on the back surface of the substrate instead of a linear shape, and there is also a case where a linear processing mark is reduced, and a large cutting force is required in the cutting step. Further, in Patent Document 2, since a processing mark of 300 μm is formed by one pulse, a linear processing mark cannot be formed on a substrate having a thickness of about 1 μm. The object of the present invention is to When the light is applied to a brittle material substrate such as a sapphire substrate, a simple device configuration is a wide modified region. X-ray [Means for Solving the Problem] The laser cutting material substrate of the first invention is advanced along the line to be cut. The pulsed laser light is irradiated to the brittle step and the second step. The step 1 is: cutting 'the method is provided with the first material substrate, the iiW cutting line is arranged; the pulse is shot on the surface of the brittle material substrate and the back is The interior 1 sweeps away from the 'and is away from the brittle layer. In the second step, the modified material is adjusted to become a modified material substrate along the line to cut, and the laser light of the fixed laser light is irradiated to the brittle material ', , and the position of the spot and enters the line 323755. 6 201236795 • Row scanning, and a plurality of linear processing marks which progress from the modified layer to the depth of the surface which does not reach the brittle material substrate are periodically formed along the line to cut. Here, the inventors of the present invention have developed a laser cutting method which can form a suitably wide modified region by a simple device, and has filed an application (Japanese Patent Application No. 2010-193220). In this laser cutting method, a linear processing trace of a predetermined length is formed from the back surface of the brittle material substrate toward the surface, and the linear processing trace is periodically formed along the line to cut. However, in, for example, a light-emitting diode, a semiconductor is laminated on a sapphire substrate to form an element. Further, when the laser cutting method of the prior art is applied to such a light-emitting diode, the laser beam is irradiated to the surface (surface) from which the element is not formed in order not to cause damage to the element. Therefore, in the method of the prior art, the modified region which is the starting point of the linear processing trace is formed on the surface (back surface) on which the element is formed. At this time, the element formed on one surface (back surface) of the substrate may be damaged. In the present invention, in the present invention, a modified layer is formed on the surface away from the surface of the brittle material substrate and the moon surface, and a linear processing mark is formed starting from the modified layer inside the substrate. Here, since the cutting line can be formed in a small number of modified regions, the quality and strength of the product can be deteriorated. In addition, the cutting in the subsequent steps can be cut off relatively easily. In addition, since the modified layer is formed in the substrate and the linear reinforcing trace progresses based on the modified layer, when the component is formed on the surface of the substrate, the component 323755 7 201236795 can be suppressed. damage. A laser cutting method according to a second aspect of the invention is the laser cutting method according to the first aspect, wherein in the second step, the beam intensity of the pulsed laser light is adjusted to be more than 8.8 x 1012 W/m 2 in the modified layer, and the surface is reached. 8xl012W/米2。 The inside of the substrate is less than 8. 8xl012W / m2. Here, since the beam intensity of the pulsed laser light in the reforming layer inside the substrate exceeds the threshold value (8.8×1012 W/m 2 ), when the scanning of the pulsed laser light is performed, the laser processing trace is the modified layer. Going toward the surface toward the slanting side as the starting point. Furthermore, in the interior of the substrate before reaching the surface, since the beam intensity is lower than the threshold (8.8×1012 W/m2), the progress of the linear processing trace upwards at the time point below the threshold value Stop, and again to form a wide range of laser processing traces. The linear processing marks extending from the modified layer to the depth of the unreached surface are periodically formed by repeating the above steps, i.e., along the line to cut. The method of the laser cutting method of the present invention is 1. 5x101GJ/m3 or less, in the second step, the energy absorbed per unit volume in the brittle material substrate is 1. 5x101GJ/m3 or less. Adjust the laser to shoot and scan conditions. ^In the laser irradiation and scanning, when the energy absorbed by each of the reference volumes exceeds 2. GxirW under the conditions of the second invention, the surface processing marks of the adjacent two-shaped processing marks are formed, and the change cannot be reduced. The quality region is therefore adjusted to be laser irradiation and scanning conditions per unit volume ° and the received energy is 2.0xl01 () J / m3 or less. The laser cutting method according to the fourth invention is the 323755 8 201236795 shot cutting method according to the first to third inventions, wherein the brittle material is sapphire. The laser cutting method according to the fifth aspect of the invention is characterized in that the pulse material substrate is cut, and the method is arranged in a first step: irradiating the laser light onto the substrate of the brittle material and scanning the predetermined line to form a scan. Brittle material: Linear laser processing marks that progress in the thickness direction of the board. ^Step 2·When the linear laser processing marks are at the substrate thickness to the pre-turn position, the laser light is stopped for the brittle material substrate. Can ^ ^ stop the stray light test (four) the irradiation of the wire ^ 1 to make the laser light irradiation position in the scanning direction = day, 'restart the laser light for the brittle material substrate. Irradiation: two to perform laser light for Each processing of the brittle material substrate is started again, and a plurality of linear laser processing traces are periodically formed along the track, 疋, ·, and: the laser beam is irradiated to the brittle material direction. The extension of the line is added to the defensive description. By this, the formation progresses toward the thickness direction of the substrate slab to the pre-station, and the line-like processing trace is applied to the base. Therefore, the timing of stopping the laser light for the substrate is stopped. Furthermore, the progress of the process is also stopped. In addition, after the scanning, the irradiation position of the light is temporarily stopped after the irradiation of the scanning, and the trace is again at the time when the laser starts the predetermined distance of the laser light to the substrate. The laser light irradiates and stops the substrate, and 323755 9 201236795 periodically forms a plurality of linear processing marks along the line to cut. As described above, in the light emitting diode, for example, the back side of the sapphire substrate is stacked. The layer semiconductor is formed with an element. Therefore, it is not preferable to form a modified region on the back surface of the substrate. On the other hand, when no element is formed on the surface of the substrate, the linear processing trace is formed to the vicinity of the surface, in the subsequent step. When the cutting is performed, it is easier to cut the substrate with less force. However, the laser cutting method by the inventor of the present invention (Japanese Patent Application _ 193220) is irradiated by laser. The condition determines the degree (length) of the progress of the linear processing marks, so it is difficult to accurately manage the length of the linear processing marks and make the linear processing marks to Therefore, in the present invention, at the time point when the linear processing mark progresses to the predetermined position, the irradiation of the laser light to the substrate is temporarily stopped, and the progress of the linear processing mark is stopped. Therefore, it is easy to progress the linear processing mark. The laser cutting process can be formed in the vicinity of the surface of the brittle material substrate without strictly managing the laser irradiation conditions. The laser cutting method according to the sixth invention is a mine according to the fifth invention. The method of cutting and cutting, wherein the third step is performed when the irradiation position of the pulsed laser light is moved to a position that does not overlap with the already formed laser processing mark. When the irradiation is stopped after the laser light is stopped, when it is formed When the laser processing trace overlaps with the newly irradiated laser light, there is a case where the formed linear processing trace further progresses to the surface of the substrate to form a planar rather than a linear processing trace. Such surface-like processing marks are not ideal because of the wide range of modified areas. 323755 10 201236795 Therefore, in the sixth invention, the irradiation of the laser light to the substrate is started again at a time point when the laser irradiation position is moved to a position where it does not overlap with the already formed laser processing mark. Thereby, it is possible to prevent the formation of the planar processing marks ‘and to form the linear laser processing marks reliably. The laser cutting method according to the seventh aspect of the invention is the laser cutting method of the fifth or sixth invention, wherein the pulsed laser light sets the irradiation condition such that the starting point of the linear laser processing mark becomes the back surface of the brittle material substrate. Here, the linear processing marks extending from the back surface of the brittle material substrate to the vicinity of the surface can be easily formed, and in the post-sequence step, the substrate can be cut more easily. The laser cutting method according to the eighth aspect of the invention is the laser cutting method according to the fifth or sixth aspect of the invention, wherein the laser light is formed at a starting point of the linear laser processing mark from the back surface of the substrate and the surface of the substrate. The method sets the laser irradiation conditions. Here, the linear processing marks are formed starting from the inside of the front and back surfaces of the brittle material substrate. Therefore, the linear processing marks are formed to extend from the inside to the surface side away from the substrate surface. Therefore, when an element is formed on the back surface of the substrate, damage to the element can be suppressed. The laser cutting method according to any one of the fifth to eighth aspects of the present invention, wherein the laser light is adjusted so that the linear processing marks of the beam intensity in the inert material substrate form a predetermined region More than 8 8 χ WW. Here, at the position which becomes the starting point of the linear processing trace, since the beam intensity of the laser light exceeds the threshold value (8.8xl012W/m2), when laser scanning is performed on the laser 323755 11 201236795, the laser processing trace is The starting point progresses towards the surface. Further, since the irradiation of the substrate by the laser light is temporarily stopped at a predetermined time point, the progress of the linear processing mark is stopped at a desired position. Thereafter, the irradiation of the laser light is started, and the linear processing marks are again formed from the starting point. By repeating the above steps, a plurality of linear processing marks are periodically formed along the line to cut. The laser cutting method according to the ninth aspect of the present invention, wherein the laser light is adjusted in such a manner that the energy absorbed per unit volume in the brittle material substrate is 2. Gxin/m3 or less. . In the case of laser irradiation and sweeping, when the energy absorbed by the unit volume exceeds 2· under the condition of the eighth gamma, the surface-shaped processing traces adjacent to the line-shaped processing marks are formed, and the modified region cannot be reduced. Therefore, in this case, the energy of the laser 阙 is difficult to be absorbed per unit volume to become 2. 〇xl 〇 °J/m3 or less. The laser cutting method of the first month is as in the fifth round - the laser of the invention_method, ^ 4 U praise month °], the brittle material is the laser processing nightmare of the 12th invention of the sapphire Face band, . # , 仏 仏 仏 〒 〒 〒 〒 〒 〒 〒 〒 〒 〒 〒 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆 脆Learning system, concentrating lens (lens), flat σ (table), moving batch also I „ sanding control unit, and processing control unit. The ray oscillating unit includes a laser continuation by the 绿 绿 green oscillator, and a laser control unit that adjusts the beam intensity of the laser light. The field is used to illuminate the single ray from the laser ray. Yingyang 70 shot the laser light to guide to 323755 12 201236795 side! ^ Poly (four) mirror money from the transmission optics (four) laser light concentrating lens. The flat wire can be relatively moved in a plane relative to the lens from the concentrating lens for mounting from the condensed material substrate. The movement control unit moves the sliding movement control ΓΓ from the condensing lens. The machining control unit controls the laser control unit and the shifting table: the brittle material is periodically formed to be placed on the flat mark. In addition, the second control is the first month b. The first function is to fix the focus position of the laser light and to enter the line === along the line to cut and to advance the thickness direction of the material substrate; the field, the linear laser processing marks in the thickness direction of the substrate Progress to the predetermined position ^ Irradiation of the laser light on the substrate of the brittle material: ==::=r_ state, == Irradiation on the substrate of the brittle material. :: Distance: Two: degree starts laser light to linear laser plus μ trace break pre-twist line and periodically forms a plurality of work mark devices, as in the foregoing, it is easy to make the line-shaped plus-shot 义 侔 侔 #f The position of the sapphire substrate can be stopped in the present invention as described above. The brittle material 323755 13 201236795 When the material substrate is processed, it is formed by a simple device, and a suitably wide modified region n is formed. When the substrate is formed with the element, damage to the element can be suppressed. Further, it is possible to easily manage the progress of the linear laser processing marks. [Embodiment] I: Processing object Fig. 1 is an example of a semiconductor wafer to which the laser cutting method of the present invention is applied. The wafer i shown in Fig. 1 is a four-layered carbonized conductor on the sapphire substrate 2, and the light-emitting element 3 having a plurality of light-emitting diodes or the like is divided by the predetermined dividing line 4. II: Laser processing apparatus Fig. 2 is a schematic block diagram showing a laser processing apparatus 5 for carrying out a processing method according to an embodiment of the present invention. The laser processing apparatus 5 has a pulsed laser ray oscillating unit 6 including a laser ray illuminator 6a and a laser controller rib; and includes a plurality of mirrors for guiding the laser light to a predetermined direction. The optical system 7; and a collecting lens 8 for collecting the laser light from the transmitting optical system 7. From the pulsed laser light source 6 (4), there is pulsed laser light (hereinafter referred to as laser light) which is subjected to irradiation conditions such as controlled beam intensity. The semiconductor wafer cassette is placed on the platform 9. The platform 9 is driven and controlled by the drive control unit 2, and is movable in the horizontal plane. That is, the semiconductor crystals placed on the stage 9 and the laser rays irradiated from the collecting lens 8 can be relatively moved in the horizontal plane. Further, the condensing lens 8 and the stage 9 having the wafer entanglement are relatively movable in the vertical direction. The laser controller 6b and the drive control unit 2 are controlled by the 323755 14 201236795 control unit 21. The processing control unit 21 is constituted by a micro computer for controlling the laser controller 6b and the drive control unit 20. ΙΠ : Laser cutting method (1) The first laser cutting method using the laser processing apparatus 5 described above is as follows. [First Step] First, in the pulsed laser light oscillating unit 6, the processing conditions such as the output power of the laser light are controlled. Further, the laser light is irradiated onto the sapphire substrate 2, and the modified region 4 is formed inside the surface and the back surface away from the sapphire substrate 2. The 'laser light' is a penetrating type of laser that penetrates the wire. Furthermore, the laser light is scanned along the line to cut. Thereby, a reforming layer along the line to cut is formed inside the substrate. Figs. 3A and 3B show a specific example of the modified layer formed inside the substrate. In either case, a sapphire substrate having a thickness of 330 was used. ° [Example 1] The laser irradiation conditions of Fig. 3A are as follows. Wavelength: 1064 nm. Pulse width: 20ps. Pulse energy: 1.4# J. Scanning speed: 500mm/s. Laser illumination direction: from the surface. Focus position: z = 100 /z m. 323755 15 201236795 In this example 1, there is a modified layer M1. It is formed in the intermediate portion of the thickness (4) of the substrate. [Example 2] The laser irradiation conditions in Fig. 3B are as follows. Wavelength: 1064 nm. Pulse width: 20ps. Pulse energy: 1. 0 / / J. Scanning speed: 50mm/s. Laser illumination direction: from the surface. Focus position · z = 140 y m. In this example 2, the layer M2. Attached to the substrate (4), the "Calling area is changed", the D-J position is 詈& repetition frequency, transmission, and _speed, but the change is made to change the position where the modified layer is formed (depth) By changing the focus position [Step 2] Then 'Controlling the output power of the laser light', and irradiating the laser light to the sapphire board's completion conditions (detailed as the focus of the rear light) (in this case with "Poly: Point 2: In the state where the fixed lightning is moved along the cutting line (4) relative to the material 3, the micrograph of the inside of the substrate is depicted in Fig. 4. Thus, there are several linear laser processing traces. g卩, VL# are not used as the complex formation of the modified region. Thus, the semiconductor wafer 1 is periodically added along the cutting line, and in the fourth figure, the back surface of the substrate is shown as the second line. = 323755 16 201236795
並非以基板背面而是以 运點而形成線狀加工痕 的雷射加工痕跡10形成於 如以上之方式，在將週期性的雷 基板内部之後，係可藉由姆形成有: 分施加彎曲應力，而易於沿著切宠 ?該雷射加工痕跡1〇的部 割線將晶圓1切斷。The laser processing mark 10 which is not formed on the back surface of the substrate but in the form of a line-shaped processing mark is formed in the above manner. After the inside of the periodic lightning substrate, the bending can be applied by: And it is easy to cut along the cutting edge of the laser processing mark 1 〇 sec.
[線狀加工痕跡之形成機制J 兹使用第5圖來說明第2步驟中之線狀加工痕跡的形 成機制。如第5圖（a)所示，以焦點位置成為基板内部之= 質層Μ附近之方式設定雷射照射條件，且照射雷射光。另 外’關於雷射光的條件將於後陳述。當照射雷射光時，如 第5圖（b)所示，藉由某雷射脈衝（以下有簡稱「脈衝」之 情形）在改質層Μ形成加工痕跡10a。 在將焦點位置亦包括在内的雷射照射條件維持在相同 條件的情況下進行雷射光掃描（第5圖（c))。如此一來，雷 射脈衝即重疊（overlap)，而在先前的加工痕跡10a上照射 下一個脈衝，由此，如第5圖（d)所示，會與先前的加工痕 跡10a相接而形成新的加工痕跡l〇b。藉由重複以上的加 工，如第5圖（e)至（g)所示，形成線狀加工痕跡10。 由於雷射光係一直將焦點位置設定於基板内部之改質 層Μ附近，因此在基板内部中，雷射射束的直徑會隨著往 上方而擴大，因此每單位面積之射束強度會變弱。再者， 在陸續形成的加工痕跡10到達基板表面之前，當射束強度 在預定的深度位置低於某值時，加工痕跡10即不會再進一 17 323755 201236795 步上升，而會再度在改質層Μ形成加工痕跡10c。兹將此 情形顯示於第5圖（h)(i)中。 藉由如上所述之加工的重複，如第5圖（j)所示，複數 個線狀加工痕跡10即沿著切斷預定線而週期性地形成。 [形成線狀加工痕跡的臨限值] 接著，說明形成如前所述之線狀加工痕跡之射束強度 的臨限值。在此，將藉由下列的計算條件計算藍寶石基板 之内部中之射束直徑的結果顯示在第7圖以後。另外，基 板内部中之射束直徑係為第6圖所示的d，而在第7圖以 後，則係顯示基板内部中之射束半徑。此外，在第7圖以 後，為了便於說明，雖將線狀加工痕跡的起點設為基板背 面，但在本發明中，線狀加工痕跡的起點並非基板背面， 而係為在第1步驟中形成於基板内部的改質層Μ。因此， 下列說明中的「基板背面」，係與本案發明之「基板内部之 改質層」對應者。 <計算條件> 雷射波長：355nm。 入射射束直徑（第6圖之Do) : 5匪。 Μ 平方（msquare) : 1. 2。 聚光透鏡8的焦點：20mm。 藍寶石折射率：1. 76。 <計算結果1 :基板厚度為150#m> 第7圖係顯不在厚度為150/zm的試料（藍寶石基板） 中，將焦點位置在以基板表面位置為「0」從+50/zm至 18 323755 201236795 -250 //m之7個階段變化時之射束半徑與高度（將基板表面 設為「0」）的計算結果。另外，第7圖係僅顯示射束之單 側，而實際之雷射光的射束形狀係夾著射束半徑「0」而對 稱。此外，在例如焦點位置「-50 v m」中，射束雖在-100 # m 的位置聚光，但此係由於雷射光在藍寶石基板内部折射之 故，而各焦點位置係顯示雷射光行進在空氣中時的值。 在此第7圖的條件中，假設下列情形。 假設1 :可藉由在射束半徑為8/zm以下的射束強度形 成加工痕跡。 假設2:在基板内部或表面的加工痕跡未形成區域中， 即使是臨限值以上的強度亦不會形成加工痕跡。即使是在 射束半徑為8/zm以下的射束強度也不會從基板内部形成 線狀加工痕跡，但從基板的背面（相當於「基板内部的改質 層」）會形成線狀加工痕跡。 在如上述的假設情形下，焦點位置與加工痕跡之關係 係從第7圖之基板内部的射束半徑推測如下（從計算結果 預測的狀態）。 +50 β m x (不可加工） 0 x (不可加工） -50 β m 〇（表面加工） -10 0 # m ◎(線狀加工） -150 /zm X (不可加工） -200 μ m X (不可加工） -250 β m — 19 323755 201236795 在此’所謂「表面加工」係指在第5圖所示之加工痕 跡的形成機制中，雷射之射束強度在基板内部的整個區域 (整個厚度）中較強，且加工痕跡到達基板表面的加工。且 體而言，觀看第7圖之焦點位置「-50以m」之射束形狀時， 在試料（基板）内部之整個厚度中，射束半徑為8//m以下。 因此’在基板内部之整個區域中，射束強度較高，且加工 痕跡係到達表面。 如此，在加工痕跡到達基板表面的表面加工中，會在 基板表面較淺的範圍内吸收所有的能量。再者，當每單位 體積吸收的能量超過某臨限值時，如第8圖所示，在基板 表面即形成均勻深度之改質區域的層12。在此種表面加工 中，不會形成目的的線狀加工痕跡。 此外，所謂「不可加工」係指在基板内部的整個區域（整 個厚度）中雷射的射束強度較低，不會形成線狀加工痕跡， 而會在表面或背面等不均勻地形成加工痕跡的加工。 再者，在第7圖之焦點位置「-i〇0/zm」中，從基板背 面至大致基板厚度之中間位置（大約為止，射束半 徑係為8 # m以下。因此，推測線狀加工痕跡會從基板背面 形成至大致一半的深度。 第9圖係顯示從以上之模擬推測之結果與實驗結果 (雷射輸出3.2W)。從該第9圖明暸’在焦點位置「__”」 ^即使改變掃描速度亦形成有線狀加工痕跡（在表中， 〇」係員示形成有線狀加工痕跡）。因此，得知在前述的 雷射…射條件下，卩「射束半徑8"m」為臨限值的假設係 323755 20 201236795 為正確者。 <計算結果2 :基板厚度為200 //m> 第10圖係顯示在厚度為200 /zm的藍寶石基板中，將 焦點位置在以基板表面位置為「0」從+50/ΖΠ1至-250/zm之 7個階段變化時之射束半徑與高度（將基板表面設為「0」） 的計算結果。另外，在此第10圖的條件中，亦與前述相同， 假設有假設1及2。 此時，焦點位置與加工痕跡的關係係從第10圖之基板 内部的射束半徑推測如下（從計算結果預測的狀態）。 +50 β in : x (不可加工） 0 : X (不可加工） -50 β m :〇（表面加工） -100/zm : ◎(線狀加工） -150；am : △(背面加工） -200 #m :χ (不可加工） -250 β m :— 在此，所謂「背面加工」係指在第5圖所示之加工痕 跡的形成機制中，加工痕跡之上升的高度較低，且所有能 量在背面之較窄的範圍内被吸收，且在基板背面（相當於 「基板内部的改質層」）附近形成均勻深度之改質區域之層 的加工。另外，如前所述，在本發明中，係以線狀加工痕 跡之起點，設為形成於基板内部雨非基板背面的改質層Μ。 因此，所謂「背面加工」，正確而言係為在第1步驟中所形 成之改質層附近形成加工痕跡為面狀的加工。 21 323755 201236795 具體而言，觀看第10圖之焦點位置「_150//m」之射 束形狀時，僅試料（基板）内部之背面附近為射束半徑8"m 以下。因此，加工痕跡不會如線狀加工上升，而如第1丨圖 所不，會在基板背面形成均勻深度（厚度）之改質區域的層 (面狀加工痕跡）13。此時，亦不會形成目的的線狀加工痕 跡0 再者，在第10圖之焦點位置「_1〇〇vm」中，推測從 基板背面，約〜75//m的高度為止，射束半徑係為8#m以 下’且涵蓋此範圍而形成線狀加工痕跡。 第12圖係顯示從以上之模擬推測之結果與實驗結果 (雷射輸出3.2W)。從該第12圖可明瞭，在焦點位置 「-lOOwra」中，即使變更掃描速度，亦形成有線狀加工痕 跡。因此，可得知在前述的雷射照射條件下，以「射束半 徑8/zm」為臨限值的假設係為正確者。 <總結> 系示上所述’雷射脈衝重疊而照射於加工痕跡時，與先 則之加工痕跡相接而形成新的加工痕跡之雷射光的射束強 度’由於為輸出3. 2W、頻率120MHz、脈衝寬度I5ps、射 束半徑8/zm，因此可得知係為& 8xi〇12w/m2。 亦即，當射束強度在成為線狀加工痕跡之起點之改質 層Μ的部分超過臨限值時，加工痕跡即上升。再者，線狀 加工痕跡到達基板表面為止，當射束強度低於臨限值時， 加工痕跡的上升即在該位置停止，且再度從改質層Μ形成 加工痕跡，結果，週期性的線狀加工痕跡即以改質層Μ為 323755 22 201236795 起點而形成。 ^線狀加工痕跡與面狀加工痕跡之間的臨限值] 形成述「背面加工」中，並非週期性地 成在掃描方向鄰接之線狀二改質層的附近’形 工痕跳夕面狀加卫」、與形成線狀加 广艮跡之線狀加工」的交界，兹檢討如下。 的位係為對厚度綱“10之藍寶石基板，將聚光點 進; 15〇/^，且以掃描速度為20〇111111/3照射雷射 =知描時之基板内部的顯微鏡相片。另外，其他雷射昭 射條件係與前述的條件相同。 觸射… 中，===背面加工(面狀加工)痕跡之 工中的條株線狀加工痕跡。亦即，該第13圖所示之加 件。第13圖中2測為面狀加工與線狀加工之交界的條 下式求出。加卫之每早位面積吸收的能量，係可藉由 徑（〇^出（；/作（掃描速度（""/咖改質層尺寸（m)x射束直 K ’在第12圖之例中，每單位面積吸收的能量 彳心ΞΓΓ對各種加工結果計算每單位面積吸 從該第14圖付知，在成為面狀加工之情 323755 23 201236795 形下’每單位面積吸收之能量為2. Oxl01Q(J/m3)以上。綜上 所述，加工狀態會以每單位面積吸收之能量2. 0x101Q( J/m3) 為臨限值變化，且在臨限值以下係形成線狀加工痕跡，當 超過臨限值時，則會形成鄰接之線狀加工痕跡相接之面狀 加工痕跡。 [總結] 總結以上說明’為了在藍寶石基板的内部形成週期性 的線狀加工痕跡，需要在下列的條件下進行加工。 (1) 將穿透性的脈衝雷射照射於美板。 (2) 使雷射脈衝在掃描方向重|。 ⑶在基板内部的改質層’射；強度為8 8xi〇lw以 上。 ⑷在到達基板表面之間’射束強度低於8. MOW。 ⑸每單位面積吸收之能量為2 (bd(r(w)以下。 在以上所述的條件下將藍寶石基板進行加工，藉此即 可沿著切斷預定線而形成性Μ狀加m㈣， 藉由形成此種線狀加工痕跡’不會使基板的強度顯著劣 化，可易於進行在後序步财的—。此外，可抑制 石基板之品質的劣化，且可將加上痕跡面積抑制得較小， 而於形成例如發光三極體做為最终製品時，可形成發光效 率佳的元件。 尤其，由於在基板内部形成改質層，且以此改f 起點而形成加工痕跡’因此可抑㈣形成於基板^ 面或背面之元件造成的損害。 323755 24 201236795 IV :雷射切割方法（2) 接著說明第2雷射切割方法。在此方法中，加工控制 部21係執行下列的處理。 (1) 將經調整射束強度之雷射光照射至基板2，並且固 定雷射光的焦點位置並沿著切斷預定線掃描，而形成朝基 板2之厚度方向進展之做為改質區域之線狀雷射加工痕 跡。 (2) 線狀加工痕跡在基板厚度方向進展至預定位置 時，即停止雷射光對於基板2的照射。另外，掃描（平台9 的移動）則繼續進行。 (3) 移動平台9，在雷射光之照射位置移動至不與既已 形成之線狀加工痕跡重疊之位置的時間點，再度開始雷射 光對於基板2的照射。 (4) 藉由重複執行以上的各處理，沿著切斷預定線4週 期性地形成複數個線狀雷射加工痕跡。 另外，雷射光對於基板2的照射及照射的停止，係藉 由雷射振盪的導通、關斷來進行。 藉由以上的加工控制部21來控制各部，且以下列的方 法來執行雷射切割。 首先，在雷射光線振盪單元6中，控制雷射光之輸出 功率等的加工條件。再者，將該雷射光照射於基板2，且 在基板2的背面形成改質區域。另外，雷射光係從未形成 有元件3之基板2的表面照射。此外，雷射光係為穿透基 板2之穿透性雷射。 25 323755 201236795 之後’在固定雷射#十杜 之位置的狀態下，使雷二焦點(在此係與「聚光點」相同) 行掃描。藉此，如基板内f著⑽預定線相對地移動進 做為改質區域之線狀雷二之顯微鏡相片的第4圖所示， 點而進展於表面#卜 痕跡10即以基板背面為起 接著’線狀雷射加工滴 帑望的位置時，停止雷射：湯0在基板厚度方向進展至所 的照射。因此，線肤λ振盪，且停止雷射光對於基板2 雷射：：痕跡10的上升亦會停止。 笛射先的照射位置移 跡10重疊的位置時，開 不與既已形成之線狀加工痕 於基板2的照射，藉^雷射振盪，且再度開始雷射光對 外的線狀加工痕跡Α。，再度以基板背面為起點而形成另 藉由重複執行以上 力°工痕跡10即沿菩，第4圖所示之複數個線狀 藉由以上方式Λ預定線而週期性地形成。 邝之後，藉由對m板内部形成複數個線狀加工痕跡 曲應力，即可划該線狀加1痕跡1G之部分施加彎 [線狀加:Γ線而易於將半導體辱圓1切斷。 L線狀加工痕跡的形成機制] 兹使用第15A及15B圖來說明藉由該第2 茂加:痕跡的機制。如第15A圖(a)所示，以焦點位置成^ =板背面附近之方式設定雷射照射條件，且照射雷射， Z射雷射光時，如第则⑹所示，藉由某雷射在 基板的背面形成加工痕跡l〇a。 衡在 在將焦點位置亦包括在内的雷射照射條件維持在相同 323755 26 201236795 條件的情況2行雷射光掃描（第15a圖⑹）。如此一來， 雷射脈衝即f 4，而在先前的加工痕跡他上照射下-個 雷射脈衝，此’如第15A_所示，會與総的加工痕 跡10“目接而形成新的加工痕跡i〇b。藉由重複以上的加 工，如第15A圖（e)牵 )至Cg)所不，形成線狀加工痕跡1〇。 再帛158圖所* ’在線狀力π工痕跡10進展至所 希望之南度的’點停止雷射振b由於雷射振盪停止， 線狀加工痕跡10的上升亦停止。 接著’在雷射光之照射位置在掃描方向行進一定距離 之後再度開始雷射振盈。藉此，再度以基板的背面為起 點而形成加工痕跡，並且線狀加工痕跡1()亦上升。 藉由重複以上的處理，如第15B圖所示，複數個線狀 加X痕跡10即沿著切斷财線而週期性地形成。 [形成線狀加工痕跡的臨限值] 關於藉由第2方法形成線狀加工痕跡的臨限值，係與 第1方法中之臨限值相同。 亦即，雷射脈衝重疊而照射於加工痕跡時，與先前之 加工痕跡相接而形成新的加工痕跡之雷射光的射束強度係 為8. 8xl012W/m2。在此’當射束強度在基板背面超過臨限值 時’加工痕跡即上升。再者’線狀加工痕跡上升至預定位 置時’只要將雷射振盪關斷而停止雷射光對於基板的照 射5使射束強度低於8. 8xl〇12W/m2，則線狀加工痕跡的上升 就會停止。再者，於雷射光之照射位置移動預定距離之後 只要將雷射振盪導通而再度開始雷射光對於基板的照射， 27 323755 201236795 就會再度以基板背面為起點而形成線狀加工痕跡。藉由重 複以上的處理，即沿著切斷預定線而週期性地形成複數個 線狀加工痕跡。 [線狀加工與面狀加工（背面加工）之間的臨限值] 關於該第2切割方法中之面狀加工（背面加工）與線狀 加工之交界，係與第1切割方法中所檢討的結果相同。 亦即，從第13圖及第14圖可得知，表面加工或背面 加工時，每單位面積吸收之能量為2. 0xl01()(J/m3)以上。因 此，加工狀態會以每單位面積吸收之能量2.0xl01Q(J/m3) 為臨限值而變化，而在臨限值以下則會形成線狀加工痕 跡，當超過臨限值時，則形成鄰接之線狀加工痕跡相接之 面狀加工痕跡。 [停止雷射振盪的距離] 接著，使用第16A圖、第16B圖及第16C圖來檢討停 止雷射振盪的距離，亦即第15B圖中之「雷射振盪off」 的時間。另外，第16A圖係顯示停止雷射振盪之距離充分 長的情形，而第16B圖及第16C圖係顯示停止雷射振盪之 距離相對較短的情形。 如第16A圖所示，再度開始雷射振盪時，既已形成之 線狀加工痕跡10與雷射光Lb不重疊的情形下，係可以背 面為起點形成加工痕跡，且可再度形成線狀加工痕跡。 另一方面，如第16B圖所示，再度開始雷射振盪時， 當既已形成之雷射加工痕跡10與雷射光Lb重疊時，既已 形成之線狀加工痕跡10即有更進一步上升的可能。當線狀 28 323755 201236795 加工痕跡ίο上升而到達基板表面時，即會成為在表面附近 形成面狀加工痕跡的表面加工，而不會週期性地形成複數 個線狀加工痕跡。 另外，第16C圖所示之例係為由於相較於第16B圖之 例，停止雷射振盪的距離較長，且相較於第16B圖之例， 雷射的輸出較低，因此既已形成之線狀加工痕跡10與雷射 光Lb的一部分雖重疊，但在既已形成之加工痕跡吸收之雷 射的能量未達到可形成線狀加工痕跡之大小時的例。此情 形下，既已形成之線狀加工痕跡10不會進一步上升。因 此，以用以將複數個線狀加工痕跡週期性地形成的條件而 言，既已形成之加工痕跡與再度開始振盪之雷射光不重疊 之點，非屬必須條件。再者，於再度開始雷射振盪之後， 當未被既已形成之加工痕跡遮蔽而到達基板背面之雷射光 超過預定的值時，即使既已形成之線狀加工痕跡與雷射光 之一部分重疊，也會以背面為基點而形成加工痕跡且再度 形成線狀加工痕跡。 [管理進展長度並形成線狀加工痕跡的具體例] <例1 > 以下顯示第17圖所示之從基板背面形成150 #m、寬 度25//m之線狀加工痕跡時的加工條件。 雷射振盡的距離1 〇n . 2 5 /i m 停止雷射振盛的距離1 off . 只要Uff2L/2+rtt3P，則再度開始雷射振盪時，雷射光 與加工痕跡不會重疊。 29 323755 201236795 L:加工痕跡尺寸。 rtop :在加工痕跡上升停止位置的射束半徑 從第18圖可得知，由於在距背面起高度為150/zm之 位置的射束半徑係為4 # m，因此L= 10 /z m時，藉由設為1 f 2 9# m，可形成複數個線狀加工痕跡。 <例2 > 以下顯示第19圖所示之從基板背面形成100//Π1、寬 度20/zm之線狀加工痕跡時的加工條件。 雷射振盪的距離: 20/zm 停止雷射振盪的距離loff : 只要Uff^L/2+rt。·)，則再度開始雷射振盪時，雷射光 與加工痕跡不會重疊。 從第20圖可得知，由於在距基板背面起高度為100# m 之位置的射束半徑係為2 //m，因此L=10 # m時，藉由設為 ，可形成複數個線狀加工痕跡。 另外，即使lQfi<L/2+rt(3P，只要加工痕跡與雷射光之 重疊充分小，即可如第16C圖所示形成線狀加工痕跡。 此外，由於線狀加工痕跡之傾斜Θ會因為雷射光的重 複頻率與掃描速度的比而變化，因此此等條件亦要適當設 定。再者，由於停止雷射振盪之1心愈小則每單位面積吸 收之能量的能量愈大，因此為了使面狀加工痕跡不會形 成，需設定成不超過前述的能量臨限值。 [因為雷射振盪導通、關斷之調整所引起之加工痕跡的 變化] 30 323755 201236795 第21A圖、第21B圖及第21C圖係顯示使雷射振盪導 通之距離（Un)、與雷射振盪關斷之距離（l〇ff)產生各種變化 時之線狀加工痕跡之變化示意圖。 第21A圖係為以雷射振盪導通之距離與雷射振盪關斷 之距離為根據設為25#m時所形成之線狀加工痕跡的示意 圖。 第21B圖係為將雷射振盪導通之距離設為25//m，且 將雷射振盪關斷之距離設為50am時所形成之線狀加工痕 跡的示意圖。在此例中，線狀加工痕跡的長度雖係與第21A 圖的情形相同，但相鄰之線狀加工痕跡的間隔變寬。因此， 相較於第21A圖之情形，做為基板整體之改質區域較窄， 而在切斷步驟中，相較於第21A圖之情形，需要較大的力。 第21C圖係為將雷射振盪導通之距離設為12.5#111， 且將雷射振盪關斷之距離設為25//m時所形成之線狀加工 痕跡的示意圖。在此例中，線狀加工痕跡的長度雖相較於 第21A圖的情形變短。此外，相鄰之線狀加工痕跡的間隔 則係與第21A圖之情形相同。在此例中，與第21B圖相同， 相較於第21A圖之情形，做為基板整體之改質區域較窄， 而在切斷步驟中，相較於第21A圖之情形，需要較大的力。 [總結] 總結以上說明，在第2雷射切割方法中，為了在藍寶 石基板的内部形成週期性的線狀加工痕跡，需要在下列的 條件下進行加工。 (1)將穿透性的脈衝雷射照射於基板。 31 323755 201236795 (2) 使雷射脈衝在掃描方向重疊。 (3) 在線狀加工痕跡的起點，每單位時間的射束強度為 8.8xl012W/m2 以上。 (4) 在線狀加工痕跡到達基板表面之前，停止雷射振 盪’使射束強度低於8. 8xl〇12W/m2。 (5) 在單位時間内每單位面積吸收之能量為2. 〇χ1〇10 (J/m3)以下。 在以上所述的條件下將藍寶石基板進行加工’藉此即 可沿著切斷預定線而形成週期性的線狀加工痕跡。尤其由 於線狀加玉痕跡進展至所希望的位置時停止雷射振後而停 止線狀加工痕跡的進展’因此可防止面狀加工痕跡的形 成而了確只地开》成複數個線狀加工痕跡。此外，可任意 控制線狀加工痕跡的進展位置。 再者，藉由形成以上的線狀加工痕跡，不會使基板的 =度顯著劣化’而可易於進行在後序步驟中的切斷。此外， 於可將加工痕跡面積抑制得較小，因此可抑制藍寶石基 質的劣化。在形成例如發光二極體做為最終製品 f，可形成發光效率佳的元件。 V :雷射切割方法（3) 例如在發光二極體中，係於藍寶石基板上疊層半導體 =成70件。在將第2雷射切割方法應用於此種發光二極 面昭射件造成的損害，係從未形成有元件的表 m照射雷射光。於是，在第2方沬士 背面，形成作為線狀加I痕跡之起的即於形成有元件的 U的改質區域。此時， 323755 32 201236795 形成於基板背面之元件會有受到損害的可能。 因此，在第3雷射切割方法中，係在遠離基板之表面 及背面的内部形成改質層，且以該基板内部之改質層為起 點而形成線狀加工痕跡。 此雷射切割方法係如下所述。另外，雷射加工裝置之 構成係與第2雷射切割方法的情形相同。 首先，在雷射光線振盪單元6中，控制雷射光之輸出 功率等的加工條件。再者，將該雷射光照射於基板2，且 在遠離基板2之表面及背面的内部形成改質區域。另外， 雷射光係為穿透基板2之穿透性雷射。再者，將該雷射光 沿著切斷預定線進行掃描。藉此，即在基板内部形成沿著 切斷預定線的改質層。 形成於基板内部之改質層的具體例，係與第3A圖及第 3B圖相同。 藉由以上方式在基板内部形成改質層後的處理，係與 第2雷射切割方法相同。亦即，以形成於基板内部之改質 層為起點，沿著切斷預定線而週期性地形成複數個線狀加 工痕跡。第22圖係顯示藉由第3方法所形成之改質層Μ、 與複數個線狀加工痕跡10的示意圖。另外，在第22圖中， 「on」係顯示雷射振盪導通的距離（時間），而「off」則係 顯示雷射振盪關斷的距離（時間）。 藉由以上方式在基板内部形成複數個線狀加工痕跡10 之後，係藉由對於形成有該線狀加工痕跡10的部分施加彎 曲應力，即可沿著切割線而易於將晶圓1切斷。 33 323755 201236795 在此第3方法中，由於可在較少的改質區域形成切割 線，因此可抑制最終製品之品質及強度劣化。此外，在後 序步驟中的切斷中，可較容易地切斷。此外，由於改質層 係形成於基板内部，而線狀加工痕跡則係以該改質層為基 點而進展，因此在基板的背面形成有元件時，可抑制對元 件造成的損害。 [其他實施形態] 本發明並不限定於以上的實施形態，在不脫離本發明 之範圍内，均可作各種變形或修正。 在前述第1步驟及第2步驟的具體例中，雖在各步驟 中改變了雷射光的波長，但當然以在兩步驟中設為相同波 長者為佳。 在前述實施形態中，雖係以藍寶石基板為例做為構成 晶圓之基板進行說明，但本發明同樣亦可應用在其他脆性 材料基板。然而，臨限值則依基板材質有所不同。 【圖式簡單說明】 第1圖係為藉由本發明之一實施形態之加工方法所切 斷之半導體晶圓的外觀斜視圖。 第2圖係為用以實施本發明之一實施形態之加工方法 之雷射加工裝置之概略構成圖。 第3A圖係為顯示形成於基板内部之改質層的顯微鏡 相片之圖。 第3B圖係為顯示形成於基板内部之改質層的顯微鏡 相片之圖。 34 323755 201236795 第4圖係為形成於基板内部之線狀加工痕跡之顯微鏡 相片之圖。 第5圖係為用以說明線狀加工痕跡之形成機制的圖。 第6圖係為用以檢討形成有線狀加工痕跡之臨限值的 裝置構成圖。 第7圖係為顯示厚度為150#m之藍寶石基板中之射束 半徑與焦點位置的關係圖。 第8圖係為顯示僅在表面形成加工痕跡之基板内部之 顯微鏡相片之圖。 第9圖係為顯示從第7圖之模擬結果預測之結果與實 驗結果的比較圖。 第10圖係為顯示厚度為200 /zm之藍寶石基板中之射 束半徑與焦點位置之關係圖。 第11圖係為顯示背面形成有加工痕跡之基板内部的 顯微鏡相片之圖。 第12圖係為顯示從模擬結果預測之結果與實驗結果 的比較圖。 第13圖係為顯示用以說明背面加工與線狀加工之交 界之基板内部之顯微鏡相片之圖。 第14圖係為顯示每單位體積吸收之能量與加工狀態 的關係之圖。 第15A圖係為用以說明線狀加工痕跡之形成機制的 圖。 第15B圖係為用以說明線狀加工痕跡之形成機制的 35 323755 201236795[Formation Mechanism of Linear Processing Traces J] Fig. 5 is used to explain the formation mechanism of the linear processing traces in the second step. As shown in Fig. 5(a), the laser irradiation conditions are set so that the focus position becomes near the inside of the substrate, and the laser beam is irradiated. In addition, the conditions regarding laser light will be stated later. When the laser light is irradiated, as shown in Fig. 5(b), the processing mark 10a is formed in the reforming layer by a certain laser pulse (hereinafter referred to as "pulse" for short). The laser scanning is performed while maintaining the same conditions for the laser irradiation conditions including the focus position (Fig. 5(c)). In this way, the laser pulse is overlapped, and the next pulse is irradiated on the previous processing trace 10a, thereby forming a contact with the previous processing trace 10a as shown in FIG. 5(d). New processing traces l〇b. By repeating the above processing, as shown in Fig. 5 (e) to (g), the linear processing marks 10 are formed. Since the laser light system always sets the focus position near the reforming layer 内部 inside the substrate, the diameter of the laser beam expands as it goes upward in the interior of the substrate, so the beam intensity per unit area becomes weak. . Furthermore, before the processing mark 10 formed successively reaches the surface of the substrate, when the beam intensity is lower than a certain value at a predetermined depth, the processing mark 10 will not rise further, and will be upgraded again. The layer Μ forms a processing trace 10c. This situation is shown in Figure 5(h)(i). By repeating the processing as described above, as shown in Fig. 5(j), a plurality of linear processing marks 10 are periodically formed along the line to cut. [Presence of forming linear processing marks] Next, the threshold value of the beam intensity for forming the linear processing marks as described above will be described. Here, the result of calculating the beam diameter in the inside of the sapphire substrate by the following calculation conditions is shown in Fig. 7 and later. Further, the beam diameter in the inside of the substrate is d shown in Fig. 6, and after Fig. 7, the beam radius in the inside of the substrate is shown. In addition, in FIG. 7 and later, for the sake of convenience of explanation, the starting point of the linear processing mark is the back surface of the substrate. However, in the present invention, the starting point of the linear processing mark is not the back surface of the substrate, but is formed in the first step. The modified layer inside the substrate. Therefore, the "back surface of the substrate" in the following description corresponds to the "modified layer inside the substrate" of the present invention. <Calculation condition> Laser wavelength: 355 nm. Incident beam diameter (Do of Figure 6): 5 匪. Μ square (msquare): 1. 2. Focus of the condenser lens 8: 20 mm. Sapphire refractive index: 1.76. <Calculation result 1: substrate thickness is 150#m> Fig. 7 shows that the focus position is not +50/zm from the surface position of the substrate to "0" in the sample (sapphire substrate) having a thickness of 150/zm. 18 323755 201236795 -250 The calculation result of the beam radius and height (the substrate surface is set to "0") when the 7 stages are changed. Further, Fig. 7 shows only one side of the beam, and the actual beam shape of the laser light is symmetrically sandwiched by the beam radius "0". Further, for example, in the focus position "-50 vm", although the beam is concentrated at a position of -100 #m, this is because the laser light is refracted inside the sapphire substrate, and each focus position indicates that the laser light travels at The value in the air. In the conditions of Fig. 7, the following cases are assumed. Hypothesis 1: A processing trace can be formed by the beam intensity at a beam radius of 8/zm or less. Hypothesis 2: In the region where the processing marks in the inside of the substrate or the surface are not formed, even the strength above the threshold does not form a processing mark. Even if the beam intensity is 8/zm or less, the linear processing marks are not formed from the inside of the substrate. However, linear processing marks are formed from the back surface of the substrate (corresponding to the "modified layer inside the substrate"). . In the assumption as described above, the relationship between the focus position and the processing trace is estimated from the beam radius inside the substrate of Fig. 7 as follows (the state predicted from the calculation result). +50 β mx (non-machineable) 0 x (non-machinable) -50 β m 〇 (surface finish) -10 0 # m ◎ (linear processing) -150 /zm X (non-machineable) -200 μ m X (not available) Machining) -250 β m — 19 323755 201236795 Here, “the so-called “surface processing” refers to the entire region (the entire thickness) of the laser beam intensity inside the substrate in the formation mechanism of the processing marks shown in FIG. 5 . Medium and strong, and processing marks reach the surface of the substrate. Further, when the beam shape of the focus position "-50 to m" in Fig. 7 is observed, the beam radius is 8/m or less over the entire thickness of the sample (substrate). Therefore, in the entire area inside the substrate, the beam intensity is high and the processing marks reach the surface. Thus, in the surface processing in which the processing trace reaches the surface of the substrate, all the energy is absorbed in a shallow range of the surface of the substrate. Further, when the energy absorbed per unit volume exceeds a certain threshold value, as shown in Fig. 8, a layer 12 of a modified region of uniform depth is formed on the surface of the substrate. In such surface processing, the desired linear processing marks are not formed. In addition, the term "unprocessable" means that the laser beam intensity is low in the entire area (the entire thickness) inside the substrate, and no linear processing marks are formed, but processing marks are unevenly formed on the surface or the back surface. Processing. In addition, in the focus position "-i〇0/zm" in Fig. 7, from the back surface of the substrate to the middle of the thickness of the substrate (the beam radius is about 8 # m or less. Therefore, it is estimated that the line processing is performed. The traces are formed from the back surface of the substrate to a depth of approximately half. Fig. 9 shows the results of the above simulation and the experimental results (laser output 3.2W). From the 9th figure, the 'focus position' __" ^ Even if the scanning speed is changed, a linear processing mark is formed (in the table, the 〇" member indicates that a linear processing mark is formed. Therefore, it is known that under the above-described laser shooting condition, the "beam radius 8 " m" is The assumption of the threshold is 323755 20 201236795 is correct. <Calculation result 2: substrate thickness is 200 //m> Fig. 10 shows the focus position on the substrate surface in a sapphire substrate having a thickness of 200 /zm The calculation result of the beam radius and height (the substrate surface is set to "0") when the position is "0" from +50/ΖΠ1 to -250/zm. In addition, the conditions in Fig. 10 In the same way as above, assume that there are hypotheses 1 and 2 At this time, the relationship between the focus position and the processing trace is estimated from the beam radius inside the substrate in Fig. 10 as follows (the state predicted from the calculation result). +50 β in : x (non-machineable) 0 : X (non-machinable) -50 β m : 〇 (surface processing) -100/zm : ◎ (linear processing) -150; am : △ (back processing) -200 #m :χ (non-processable) -250 β m :- Here, The term "back surface processing" means that in the formation mechanism of the processing marks shown in Fig. 5, the height of the rise of the processing marks is low, and all the energy is absorbed in a narrow range of the back surface, and is on the back surface of the substrate (equivalent In the vicinity of the "modified layer inside the substrate", a layer of a layer of a modified region having a uniform depth is formed. Further, as described above, in the present invention, the starting point of the linear processing trace is formed inside the substrate. Therefore, the "back surface processing" is a process in which the processing marks are formed in the vicinity of the reforming layer formed in the first step. , watch the focus position of Figure 10 "_150// In the beam shape of m", only the vicinity of the back surface of the inside of the sample (substrate) is equal to or less than the beam radius of 8 " m. Therefore, the processing marks do not rise as linear processing, but as in the first drawing, the substrate is A layer (planar processing mark) 13 of a modified region having a uniform depth (thickness) is formed on the back surface. At this time, a target linear processing trace is not formed. 0. In the focus position of FIG. 10, "_1〇〇vm In the case of the back surface of the substrate, the beam radius is 8#m or less from the height of about 750/m, and the range is covered to form a linear processing mark. Figure 12 shows the results of the above simulation and experimental results (laser output 3.2W). As can be seen from Fig. 12, in the focus position "-lOOwra", even if the scanning speed is changed, a linear processing trace is formed. Therefore, it can be seen that under the above-described laser irradiation conditions, the assumption that the "beam radius 8/zm" is the threshold value is correct. The result of the output is 3. 2W, the beam intensity of the laser beam is the same as the output of the laser beam. The frequency is 120MHz, the pulse width is I5ps, and the beam radius is 8/zm. Therefore, it can be known that it is & 8xi〇12w/m2. That is, when the beam intensity exceeds the threshold value in the portion of the reforming layer which is the starting point of the linear processing mark, the processing mark rises. Furthermore, when the linear processing trace reaches the surface of the substrate, when the beam intensity is lower than the threshold value, the rise of the processing mark stops at the position, and the processing trace is again formed from the modified layer, and as a result, the periodic line The trace of the processing is formed by the modified layer 323 as the starting point of 323755 22 201236795. ^The threshold value between the linear processing trace and the planar processing trace] In the formation of "back surface processing", it is not periodically formed in the vicinity of the linear two-modified layer adjacent to the scanning direction. The boundary between the shape and the "linear processing of the line-shaped widening track" is reviewed below. The position is a microscopic photograph of the inside of the substrate when the thickness of the sapphire substrate is 10, and the spotlight is entered; 15 〇 / ^, and the scanning speed is 20 〇 11111 1/3. The other laser radiation conditions are the same as those described above. In the contact..., === the line-like processing mark in the work of the back surface processing (planar processing). That is, the figure shown in Fig. 13 In the figure of Fig. 13, the measurement of the boundary between the surface processing and the linear processing is obtained by the following equation. The energy absorbed by each morning area of the reinforcement can be obtained by the diameter (;/出(Scanning speed (""/Caf sizing size (m) x beam straight K' In the example of Fig. 12, the energy absorbed per unit area 彳 heart 计算 is calculated for each processing result per unit area According to the 14th figure, the energy absorbed per unit area is 2. Oxl01Q (J/m3) or more in the form of planar processing. In view of the above, the processing state is absorbed per unit area. Energy 2. 0x101Q( J/m3) is a change in the threshold value, and below the threshold value, a linear processing trace is formed. When the threshold value is reached, the surface processing marks that are adjacent to the line-shaped processing marks are formed. [Summary] To summarize the above description, in order to form periodic linear processing marks inside the sapphire substrate, it is necessary to be under the following conditions. (1) A penetrating pulsed laser is irradiated onto the US plate. (2) The laser pulse is made heavy in the scanning direction. (3) The modified layer inside the substrate is shot; the intensity is 8 8xi〇lw or more. (4) The beam intensity is less than 8. MOW between the surfaces of the substrate. (5) The energy absorbed per unit area is 2 (bd(r(w) or less.) The sapphire substrate is processed under the conditions described above. Therefore, it is possible to form a shape of m (4) along the line to be cut, and by forming such a line-shaped processing mark, the strength of the substrate is not significantly deteriorated, and it is easy to carry out the subsequent steps. The deterioration of the quality of the stone substrate is suppressed, and the area of the added trace can be suppressed to be small, and when the light-emitting triode is formed as a final product, for example, an element having good light-emitting efficiency can be formed. Quality layer f The starting point forms a processing mark' Therefore, it can suppress (4) damage caused by components formed on the surface of the substrate or the back surface. 323755 24 201236795 IV : Laser cutting method (2) Next, the second laser cutting method will be described. The processing control unit 21 performs the following processing: (1) Irradiating the adjusted beam intensity of the laser light to the substrate 2, and fixing the focus position of the laser light and scanning along the line to cut to form a thickness toward the substrate 2. The direction progresses as a linear laser processing trace of the modified region. (2) When the linear processing trace progresses to a predetermined position in the thickness direction of the substrate, the irradiation of the laser light to the substrate 2 is stopped. In addition, the scan (movement of platform 9) continues. (3) The moving platform 9 restarts the irradiation of the laser light to the substrate 2 at a time point when the irradiation position of the laser light is moved to a position where it does not overlap with the linear processing mark which has already been formed. (4) By repeating the above respective processes, a plurality of linear laser processing marks are periodically formed along the line to cut 4 . Further, the irradiation of the substrate 2 by the laser light and the stop of the irradiation are performed by turning on and off the laser oscillation. Each of the sections is controlled by the above-described processing control unit 21, and laser cutting is performed by the following method. First, in the laser beam oscillation unit 6, processing conditions such as the output power of the laser light are controlled. Further, the laser light is irradiated onto the substrate 2, and a modified region is formed on the back surface of the substrate 2. Further, the laser light is irradiated from the surface of the substrate 2 on which the element 3 is not formed. In addition, the laser light is a penetrating laser that penetrates the substrate 2. 25 323755 201236795 After the 'fixed laser #十杜 position, the Ray II focus (the same as the "concentrated spot") is scanned. Thereby, as shown in FIG. 4 of the microscope photograph in which the predetermined line in the substrate is relatively moved (10) into the linear region of the modified region, the point proceeds to the surface of the substrate. Then, when the position of the linear laser processing is dropped, the laser is stopped: the soup 0 progresses to the irradiation in the thickness direction of the substrate. Therefore, the line skin λ oscillates, and the laser light is stopped for the substrate 2: the rise of the trace 10 is also stopped. When the first irradiation position of the flute is overlapped, the linear processing marks which have been formed are not irradiated with the substrate 2, and the laser processing is started, and the linear processing marks outside the laser light are again started. Then, the back surface of the substrate is again formed as a starting point, and the above-described force traces 10 are repeatedly performed, and the plurality of lines shown in Fig. 4 are periodically formed by the predetermined line. After the crucible, a plurality of linear processing trace stresses are formed on the inside of the m-plate, and the portion in which the trace is added to the trace 1G can be applied in a linear shape: the line is twisted and the twisted line is easily cut. Formation Mechanism of L-Line Processing Traces] Figures 15A and 15B are used to illustrate the mechanism by which the second addition: traces. As shown in Fig. 15A (a), the laser irradiation conditions are set such that the focus position is near the back side of the board, and the laser is irradiated, and when the Z laser light is emitted, as shown in the sixth (6), by a certain laser A processing trace l〇a is formed on the back surface of the substrate. The balance is in the case of the same 323755 26 201236795 conditional laser illumination conditions including the focus position (2a (6)). In this way, the laser pulse is f 4 , and the previous processing trace is irradiated with a laser pulse, which, as shown in the 15A_, will be connected with the processing mark 10 of the crucible to form a new one. Processing trace i〇b. By repeating the above processing, as shown in Fig. 15A (e) to Cg), a linear processing trace is formed. 1 帛 Figure 158 * 'Linear force π work trace 10 Progression to the desired south point of the 'point stop laser vibration b is stopped due to the laser oscillation, and the rise of the linear processing trace 10 is also stopped. Then 'the laser is restarted after the laser beam is irradiated at a certain distance in the scanning direction. By this, the processing marks are formed again from the back surface of the substrate, and the linear processing marks 1() are also increased. By repeating the above processing, as shown in Fig. 15B, a plurality of linear X-marks are added. 10 is formed periodically along the cutting line. [Prevention of the line-shaped processing marks] The threshold value for forming the linear processing marks by the second method is the threshold in the first method. The values are the same. That is, when the laser pulses overlap and illuminate the processing marks, The beam intensity of the laser light that the previous processing marks are joined to form a new processing mark is 8. 8xl012W/m2. Here, when the beam intensity exceeds the threshold value on the back side of the substrate, the processing mark rises. 'When the linear processing trace is raised to the predetermined position, as long as the laser oscillation is turned off and the laser light is stopped for the substrate 5 so that the beam intensity is lower than 8. 8xl 〇 12W/m2, the linear processing trace will rise. In addition, after the predetermined distance is moved by the irradiation position of the laser light, the laser light is turned on and the laser light is again irradiated to the substrate, and 27 323755 201236795 will again form a linear processing mark starting from the back surface of the substrate. A plurality of linear processing marks are periodically formed by repeating the above processing, that is, along the line to cut. [The threshold value between the line processing and the surface processing (back processing)] The second cutting method The boundary between the planar processing (back processing) and the linear processing is the same as that reviewed in the first cutting method. That is, it can be seen from Fig. 13 and Fig. 14 that the surface is processed or backed. When processing, the energy absorbed per unit area is 2. 0xl01()(J/m3) or more. Therefore, the processing state changes by the energy absorbed per unit area of 2.0xl01Q (J/m3), and A linear processing mark is formed below the threshold value, and when it exceeds the threshold value, a planar processing mark in which adjacent linear processing marks are adjacent to each other is formed. [Stop the laser oscillation distance] Next, using FIG. 16A, Figures 16B and 16C are used to review the distance at which the laser oscillation is stopped, that is, the time of "laser oscillation off" in Fig. 15B. Further, Fig. 16A shows a case where the distance at which the laser oscillation is stopped is sufficiently long, and Figs. 16B and 16C show a case where the distance at which the laser oscillation is stopped is relatively short. As shown in Fig. 16A, when the laser oscillation is started again, in the case where the linear processing mark 10 and the laser light Lb which have been formed do not overlap each other, the processing mark can be formed on the back side as a starting point, and the linear processing trace can be formed again. . On the other hand, as shown in Fig. 16B, when the laser oscillation is started again, when the already formed laser processing trace 10 overlaps with the laser light Lb, the linear processing trace 10 which has been formed has a further rise. may. When the linear 28 323755 201236795 processing mark ίο rises and reaches the surface of the substrate, it becomes a surface processing for forming a planar processing mark near the surface, and a plurality of linear processing marks are not periodically formed. In addition, the example shown in Fig. 16C is because the distance for stopping the laser oscillation is longer than that of the case of Fig. 16B, and the output of the laser is lower than that of the case of Fig. 16B, The formed linear processing trace 10 overlaps with a part of the laser light Lb, but the energy of the laser absorbed by the formed processing trace does not reach a size at which a linear processing trace can be formed. In this case, the linear processing trace 10 which has been formed does not rise further. Therefore, in order to periodically form a plurality of linear processing marks, it is not a necessary condition that the formed processing marks do not overlap with the laser light that starts to oscillate again. Furthermore, after the laser oscillation is resumed, when the laser light that has not been shielded by the formed processing marks and reaches the back surface of the substrate exceeds a predetermined value, even if the formed linear processing mark partially overlaps with the laser light, The processing marks are also formed on the back side and the linear processing marks are formed again. [Specific Example of Managing Progressive Length and Forming Linear Processing Traces] <Example 1 > The processing conditions for forming a linear processing mark of 150 #m and width 25//m from the back surface of the substrate as shown in Fig. 17 are shown below. . The distance the laser is vibrated is 1 〇n . 2 5 /i m The distance at which the laser oscillates to stop 1 off . As long as Uff2L/2+rtt3P, the laser light and the machining trace do not overlap when the laser oscillation is started again. 29 323755 201236795 L: Processing trace size. Rtop : The beam radius at the stop position of the processing mark rise and fall is shown in Fig. 18. Since the beam radius at the position of 150/zm from the back surface is 4 # m, when L = 10 /zm, By setting 1 f 2 9# m, a plurality of linear processing marks can be formed. <Example 2 > The processing conditions when the linear processing marks of 100//1 and width 20/zm were formed from the back surface of the substrate as shown in Fig. 19 are shown below. Laser oscillation distance: 20/zm Stop the laser oscillation distance loff: As long as Uff^L/2+rt. ·), when the laser oscillation is started again, the laser light does not overlap with the machining marks. As can be seen from Fig. 20, since the beam radius at a position of 100# m from the back surface of the substrate is 2 // m, when L = 10 # m, by setting, a plurality of lines can be formed. Shape processing marks. In addition, even if lQfi < L / 2 + rt (3P, as long as the overlap of the processing trace and the laser light is sufficiently small, a linear processing trace can be formed as shown in Fig. 16C. In addition, since the tilt of the linear processing trace is due to The ratio of the repetition frequency of the laser light to the scanning speed varies, and therefore these conditions are also appropriately set. Further, since the smaller the center of the laser oscillation is stopped, the energy per unit area of energy is increased, so The surface processing marks are not formed and should be set so as not to exceed the above-mentioned energy threshold. [Because of the change in processing marks caused by the adjustment of the laser oscillation conduction and turn-off] 30 323755 201236795 21A, 21B and Fig. 21C is a diagram showing the change of the linear processing trace when the laser oscillation is turned on (Un) and the laser oscillation is turned off (l〇ff). The 21A is a laser. The distance between the oscillation conduction distance and the laser oscillation off is a schematic diagram based on the linear processing trace formed when the angle is 25#m. The 21B is a distance at which the laser oscillation is turned on is 25//m, and Laser oscillation off A schematic diagram of the linear processing marks formed when the distance is 50 mm. In this example, the length of the linear processing marks is the same as in the case of Fig. 21A, but the interval between the adjacent linear processing marks is widened. Therefore, compared with the case of Fig. 21A, the modified region as the whole substrate is narrow, and in the cutting step, a larger force is required than in the case of Fig. 21A. Fig. 21C is for The distance between the laser oscillation conduction is set to 12.5#111, and the linear processing trace formed when the laser oscillation is turned off by 25//m is used. In this example, the length of the linear processing trace is The situation is shorter than in the case of Fig. 21A. Further, the interval between the adjacent linear processing marks is the same as in the case of Fig. 21A. In this example, as in Fig. 21B, compared with Fig. 21A In the case, the modified region as the whole substrate is narrow, and in the cutting step, a larger force is required than in the case of Fig. 21A. [Summary] To summarize the above description, in the second laser cutting method In order to form periodic linear processing marks inside the sapphire substrate, Processing is performed under the following conditions: (1) A penetrating pulsed laser is irradiated onto the substrate. 31 323755 201236795 (2) The laser pulses are superimposed in the scanning direction. (3) The starting point of the linear processing trace, per unit The beam intensity of the time is 8.8xl012W/m2 or more. (4) Before the linear processing trace reaches the surface of the substrate, stop the laser oscillation 'to make the beam intensity lower than 8. 8xl 〇 12W/m2. (5) In unit time The energy absorbed per unit area is 2. 〇χ1〇10 (J/m3) or less. The sapphire substrate is processed under the conditions described above, thereby forming a periodic line along the line to cut. Processing marks. In particular, since the progress of the linear processing marks is stopped after the laser-like jade marks are advanced to the desired position, the progress of the linear processing marks is stopped, so that the formation of the surface-shaped processing marks can be prevented, and only a plurality of linear processing can be performed. trace. In addition, the progress position of the linear processing marks can be arbitrarily controlled. Further, by forming the above linear processing marks, the cutting in the subsequent step can be easily performed without significantly deteriorating the degree of the substrate. Further, since the area of the processing trace can be suppressed to be small, deterioration of the sapphire substrate can be suppressed. In forming, for example, a light-emitting diode as the final product f, an element having excellent light-emitting efficiency can be formed. V: Laser cutting method (3) For example, in a light-emitting diode, a semiconductor is laminated on a sapphire substrate = 70 pieces. In the case where the second laser cutting method is applied to the damage caused by such a light-emitting diode surface, the laser light is irradiated to the surface m from which the element is not formed. Then, on the back side of the second party gentleman, a modified region which is a line-shaped plus I mark, that is, a U in which the element is formed is formed. At this time, 323755 32 201236795 components formed on the back surface of the substrate may be damaged. Therefore, in the third laser cutting method, a modified layer is formed inside the surface and the back surface away from the substrate, and a linear processing mark is formed with the modified layer inside the substrate as a starting point. This laser cutting method is as follows. Further, the configuration of the laser processing apparatus is the same as that of the second laser cutting method. First, in the laser beam oscillation unit 6, processing conditions such as the output power of the laser light are controlled. Further, the laser light is irradiated onto the substrate 2, and a modified region is formed inside the surface and the back surface away from the substrate 2. In addition, the laser light is a penetrating laser that penetrates the substrate 2. Further, the laser light is scanned along the line to cut. Thereby, a reforming layer along the line to cut is formed inside the substrate. Specific examples of the reforming layer formed inside the substrate are the same as those in Figs. 3A and 3B. The treatment after forming the reformed layer inside the substrate by the above method is the same as the second laser cutting method. That is, a plurality of linear processing marks are periodically formed along the line to cut starting from the reforming layer formed inside the substrate. Fig. 22 is a schematic view showing the modified layer 形成 formed by the third method and a plurality of linear processing marks 10. In addition, in Fig. 22, "on" indicates the distance (time) at which the laser oscillation is turned on, and "off" indicates the distance (time) at which the laser oscillation is turned off. By forming a plurality of linear processing marks 10 in the substrate as described above, it is possible to easily cut the wafer 1 along the dicing line by applying a bending stress to the portion where the linear processing marks 10 are formed. 33 323755 201236795 In the third method, since the dicing line can be formed in a small number of modified regions, deterioration in quality and strength of the final product can be suppressed. Further, in the cutting in the subsequent step, the cutting can be performed relatively easily. Further, since the modified layer is formed inside the substrate, the linear processing marks progress based on the modified layer. Therefore, when the element is formed on the back surface of the substrate, damage to the element can be suppressed. [Other Embodiments] The present invention is not limited to the above embodiments, and various modifications and changes can be made without departing from the scope of the invention. In the specific examples of the first step and the second step, although the wavelength of the laser light is changed in each step, it is of course preferable to set the same wavelength in both steps. In the above embodiment, the sapphire substrate is exemplified as a substrate constituting the wafer. However, the present invention is also applicable to other brittle material substrates. However, the threshold varies depending on the substrate material. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing the appearance of a semiconductor wafer cut by a processing method according to an embodiment of the present invention. Fig. 2 is a schematic block diagram of a laser processing apparatus for carrying out a processing method according to an embodiment of the present invention. Fig. 3A is a view showing a microscope photograph of a modified layer formed inside the substrate. Fig. 3B is a view showing a microscope photograph of the modified layer formed inside the substrate. 34 323755 201236795 Figure 4 is a photo of a microscope photograph of a linear processing trace formed inside the substrate. Fig. 5 is a view for explaining the formation mechanism of the linear processing marks. Fig. 6 is a view showing a configuration of a device for reviewing the threshold value for forming a linear processing mark. Fig. 7 is a graph showing the relationship between the beam radius and the focus position in a sapphire substrate having a thickness of 150 #m. Fig. 8 is a view showing a micrograph of the inside of a substrate on which only a processing mark is formed on the surface. Figure 9 is a comparison chart showing the results predicted from the simulation results of Fig. 7 and the experimental results. Figure 10 is a graph showing the relationship between the beam radius and the focus position in a sapphire substrate having a thickness of 200 / zm. Fig. 11 is a view showing a micrograph of the inside of the substrate on which the processing marks are formed on the back surface. Figure 12 is a comparison of the results predicted from the simulation results with the experimental results. Fig. 13 is a view showing a micrograph of the inside of the substrate for explaining the boundary between the back surface processing and the line processing. Figure 14 is a graph showing the relationship between the energy absorbed per unit volume and the processing state. Fig. 15A is a view for explaining the formation mechanism of the linear processing marks. Figure 15B is a diagram to illustrate the formation mechanism of linear processing marks 35 323755 201236795
第16A圖係為用以說明雷射振盪之導通（on)、關斷 (off)距離與線狀加工痕跡之關係的圖。 第16B圖係為用以說明雷射振盪之導通、關斷距離與 線狀加工痕跡之關係的圖。 第16C圖係為用以說明雷射振盪之導通、關斷距離與 線狀加工痕跡之關係的圖。 第17圖係為用以說明暫時停止雷射振盪並形成所希 望長度之線狀加工痕跡之具體例1的圖。 第18圖係為顯示第17圖之例中之基板内部的射束半 徑之圖。 第19圖係為用以說明暫時停止雷射振盪並形成所希 望長度之線狀加工痕跡之具體例2的圖。 第20圖係為顯示第19圖之例中之基板内部的射束半 徑之圖。 第21A圖係為用以說明雷射振烫之導通、關斷距離之 調整與藉由調整所形成之線狀加工痕跡之關係的圖。 第21B圖係為用以說明雷射振盪之導通、關斷距離之 調整與藉由調整所形成之線狀加工痕跡之關係的圖。 第21C圖係為用以說明雷射振盪之導通、關斷距離之 調整與藉由調整所形成之線狀加工痕跡之關係的圖。 第22圖係為以基板内部之改質層為起點所形成之線 狀加工痕跡的示意圖。 【主要元件符號說明】 323755 36 201236795 1 晶圓 2 藍寶石基板 3 發光元件 4 切斷預定線 5 雷射加工裝置 6 脈衝雷射光線振盡單元 6a 雷射光線振盪器 6b 雷射控制器 7 傳送光學系統 8 聚光透鏡 9 平台 10 線狀加工痕跡 10a 、10b 、 10c 加工痕跡 12、 13 層 20 驅動控制部 21 加工控制部 Lb 雷射光 M、 Ml 至 M3 改質層 37 323755Fig. 16A is a view for explaining the relationship between the on and off distances of the laser oscillation and the linear processing marks. Fig. 16B is a view for explaining the relationship between the on and off distances of the laser oscillation and the linear processing marks. Fig. 16C is a diagram for explaining the relationship between the conduction and the turning distance of the laser oscillation and the linear processing trace. Fig. 17 is a view for explaining a specific example 1 of temporarily stopping the laser oscillation and forming a linear processing mark of a desired length. Fig. 18 is a view showing a beam radius inside the substrate in the example of Fig. 17. Fig. 19 is a view for explaining a specific example 2 of temporarily stopping the laser oscillation and forming a linear processing mark of a desired length. Fig. 20 is a view showing the beam radius inside the substrate in the example of Fig. 19. Fig. 21A is a view for explaining the relationship between the adjustment of the turn-on and turn-off distance of the laser blasting and the linear processing marks formed by the adjustment. Fig. 21B is a view for explaining the relationship between the adjustment of the ON and OFF distances of the laser oscillation and the linear processing marks formed by the adjustment. Fig. 21C is a view for explaining the relationship between the adjustment of the ON and OFF distances of the laser oscillation and the linear processing marks formed by the adjustment. Fig. 22 is a schematic view showing a linear processing mark formed by using a modified layer inside the substrate as a starting point. [Description of main component symbols] 323755 36 201236795 1 Wafer 2 Sapphire substrate 3 Light-emitting element 4 Cut-off line 5 Laser processing device 6 Pulse laser light-shocking unit 6a Laser beam oscillator 6b Laser controller 7 Transmission optics System 8 Condenser lens 9 Platform 10 Linear processing marks 10a, 10b, 10c Processing marks 12, 13 Layer 20 Drive control unit 21 Processing control unit Lb Laser light M, Ml to M3 Modification layer 37 323755