TWI546852B - Laser processing method - Google Patents

Laser processing method Download PDF

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TWI546852B
TWI546852B TW101100603A TW101100603A TWI546852B TW I546852 B TWI546852 B TW I546852B TW 101100603 A TW101100603 A TW 101100603A TW 101100603 A TW101100603 A TW 101100603A TW I546852 B TWI546852 B TW I546852B
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cut
line
sic substrate
modified region
along
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TW101100603A
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TW201246331A (en
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Junji Okuma
Takeshi Sakamoto
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Hamamatsu Photonics Kk
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/064Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/0006Working by laser beam, e.g. welding, cutting or boring taking account of the properties of the material involved
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08Devices involving relative movement between laser beam and workpiece
    • B23K26/083Devices involving movement of the workpiece in at least one axial direction
    • B23K26/0853Devices involving movement of the workpiece in at least in two axial directions, e.g. in a plane
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/50Working by transmitting the laser beam through or within the workpiece
    • B23K26/53Working by transmitting the laser beam through or within the workpiece for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00Articles made by soldering, welding or cutting
    • B23K2101/18Sheet panels
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00Articles made by soldering, welding or cutting
    • B23K2101/36Electric or electronic devices
    • B23K2101/40Semiconductor devices
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00Materials to be soldered, welded or cut
    • B23K2103/50Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Dicing (AREA)
  • Laser Beam Processing (AREA)
  • Processing Of Stones Or Stones Resemblance Materials (AREA)

Description

雷射加工方法 Laser processing method

本發明係關於用來將具備SiC基板之板狀加工對象物沿著切斷預定線予以切斷之雷射加工方法。 The present invention relates to a laser processing method for cutting a plate-shaped object to be processed having a SiC substrate along a line to cut.

近年,作為可製造具有優良的耐熱性、耐高電壓性、省電力性之功率元件的半導體材料,碳化矽(SiC;Silicon Carbide)被注目。但,由於SiC係具有僅次於鑽石的硬度之難加工材料,故,當藉由刀式切割,欲將具備SiC基板之板狀加工對象物切斷時,必須要進行低速度之加工、頻繁的刀片更換等。因此,提案有藉由對加工對象物照射雷射光,沿著切斷預定線,在SiC基板的內部形成改質區域,以該改質區域作為起點,沿著切斷預定線切斷加工對象物之雷射加工方法(參照例如專利文獻1)。 In recent years, as a semiconductor material capable of producing a power element having excellent heat resistance, high voltage resistance, and power saving, SiC (Silicon Carbide) has been attracting attention. However, since the SiC system has a hard-to-machine material that is second only to the hardness of the diamond, it is necessary to perform low-speed processing and frequent cutting of the plate-shaped object to be processed with the SiC substrate by knife cutting. Blade replacement, etc. Therefore, it is proposed to form a modified region in the SiC substrate along the line to cut along the line to be cut, and to cut the object along the line to cut with the modified region as a starting point. Laser processing method (see, for example, Patent Document 1).

[專利文獻1]日本特表2007-514315號公報 [Patent Document 1] Japanese Patent Publication No. 2007-514315

本發明者們發現,在藉由上述這種雷射加工方法,切斷具備具有c面與形成斜角分量的角度的主面之六方晶系SiC基板之板狀加工對象物之情況,存在有下述課題。即,當沿著朝與主面及a面平行的方向延伸之第1切斷預定 線,在SiC基板的內部形成第1改質區域,而沿著朝與主面及m面平行的方向延伸之第2切斷預定線,在SiC基板的內部形成第2改質區域時,會有沿著第1切斷預定線之切斷精度較沿著第2切斷預定線之切斷精度劣化之虞。又,本發明者們發現,這是起因於自第2改質區域起,龜裂容易朝SiC基板的厚度方向伸展,相對於此,自第1改質區域起,龜裂不易朝SiC基板的厚度方向伸展。 The present inventors have found that a plate-shaped object to be processed having a hexagonal SiC substrate having a c-plane and a principal surface forming an angle of an oblique component is cut by the above-described laser processing method. The following topics. That is, when the first cutting schedule is extended in a direction parallel to the main surface and the a surface In the line, the first modified region is formed inside the SiC substrate, and when the second modified region is formed inside the SiC substrate along the second planned cutting line extending in the direction parallel to the main surface and the m-plane, There is a possibility that the cutting accuracy along the first cutting planned line is deteriorated compared to the cutting accuracy along the second cutting planned line. Further, the inventors of the present invention have found that the crack tends to extend in the thickness direction of the SiC substrate from the second modified region, whereas the crack is less likely to be toward the SiC substrate from the first modified region. Stretch in the thickness direction.

因此,本發明之目的係在於提供將具備具有與c面呈斜角分量的角度之主面的六方晶系SiC基板之板狀加工對象物沿著切斷預定線,可精度良好地予以切斷之雷射加工方法。 In view of the above, it is an object of the present invention to provide a plate-shaped object to be processed having a hexagonal SiC substrate having a principal surface having an oblique angle component to the c-plane, and to cut it accurately along a line to cut. Laser processing method.

本發明的一觀點之雷射加工方法,係將具備具有與c面呈斜角分量的角度之主面的六方晶系SiC基板之板狀加工對象物,分別沿著朝與主面及a面平行的方向延伸之第1切斷預定線以及朝與主面及m面平行的方向延伸之第2切斷預定線予以切斷之雷射加工方法,其特徵為具備有:第1製程,其係藉由使雷射光的聚光點對位於SiC基板的內部,沿著第1切斷預定線,對加工對象物照射雷射光,來沿著第1切斷預定線,將作為切斷起點的第1改質區域形成於SiC基板的內部;和第2製程,其係在進行了第1製程後,藉由將聚光點對位於SiC基板的內部,沿著沿著第2切斷預定線,對加 工對象物照射雷射光,來沿著第2切斷預定線,將作為切斷起點的第2改質區域形成於SiC基板的內部。 According to a laser processing method of the present invention, a plate-shaped object to be processed having a hexagonal SiC substrate having a principal surface having an oblique angle component to the c-plane is provided along the principal surface and the a-plane A laser processing method in which a first cutting planned line extending in a parallel direction and a second cutting planned line extending in a direction parallel to the main surface and the m-plane are cut, wherein the first processing method is provided. By arranging the light-converging point of the laser light in the inside of the SiC substrate, the object to be processed is irradiated with the laser beam along the first line to cut, and the first line to cut is used as the starting point of the cutting. The first modified region is formed inside the SiC substrate; and the second process is performed after the first process is performed, and the spot is positioned inside the SiC substrate along the second cutting line. , plus The object is irradiated with laser light to form a second modified region as a cutting start point in the inside of the SiC substrate along the second line to cut.

在此雷射加工方法,在形成用來使龜裂朝SiC基板的厚度方向伸展之條件為和緩的第2改質區域之前,形成用來使龜裂朝SiC基板的厚度方向的條件為嚴苛之第1改質區域。藉此,當第1改質區域的形成時,在第1切斷預定線與第2切斷預定線交叉之部分,能夠防止從第1改質區域朝SiC基板的厚度方向之龜裂的伸展被第2改質區域所阻礙之情況產生。因此,若依據此雷射加工方法,能沿著切斷預定線,將具備具有與c面呈斜角分量的角度的主面之六方晶系SiC基板之板狀加工對象物精度良好地予以切斷精度良好地予以切斷。再者,斜角係包含0°的情況。在此情況,主面係與c面呈平行。 In the laser processing method, the conditions for forming the crack toward the thickness direction of the SiC substrate are severe before forming the second modified region in which the crack is extended in the thickness direction of the SiC substrate. The first modified area. By this, when the first modified region is formed, it is possible to prevent the crack from the first modified region toward the thickness direction of the SiC substrate in the portion where the first planned cutting line intersects with the second planned cutting line. It is caused by the situation that the second modified area is blocked. Therefore, according to the laser processing method, the plate-shaped object to be processed having the hexagonal SiC substrate having the principal surface having an oblique angle component to the c-plane can be accurately cut along the line to be cut. The cutting accuracy is cut off well. Furthermore, the bevel angle includes 0°. In this case, the main surface is parallel to the c-plane.

本發明的一觀點之雷射加工方法,亦可進一步具備有:在第2製程後,以第1改質區域作為起點,沿著第1切斷預定線切斷加工對象物,以第2改質區域作為起點,沿著第2切斷預定線切斷加工對象物之第3製程。藉此,能夠獲得沿著切斷預定線被精度良好地切斷之加工對象物。再者,亦可在沿著第1切斷預定線進行切斷後,再實施沿著第2切斷預定線之切斷,亦可在沿著第2切斷預定線之切斷後,再實施沿著第1切斷預定線之切斷。 In the laser processing method of the first aspect of the invention, the first modified region is used as a starting point, and the object to be processed is cut along the first cutting line, and the second modification is performed. The material region serves as a starting point, and the third process of cutting the object to be processed is cut along the second line to cut. Thereby, it is possible to obtain an object to be processed which is accurately cut along the line to cut. Further, after the cutting is performed along the first cutting planned line, the cutting along the second cutting planned line may be performed, or the cutting may be performed along the second cutting planned line. The cutting of the first cutting planned line is performed.

在本發明的一觀點之雷射加工方法,具有第1改質區域及第2改質區域係包含熔融處理區域之情況。 In the laser processing method according to one aspect of the present invention, the first modified region and the second modified region may include a molten processed region.

若依據本發明,沿著切斷預定線,能將具備具有與c面呈斜角分量的角度的主面之六方晶系SiC基板之板狀加工對象物精度良好地予以切斷。 According to the present invention, the plate-shaped object to be processed having the hexagonal SiC substrate having the principal surface having an oblique angle component to the c-plane can be accurately cut along the line to be cut.

以下,參照圖面,詳細地說明關於本發明的理想實施形態。再者,在各圖中,針對相圖或相當部分賦予相同圖號,並省略其重複說明。 Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. In the respective drawings, the same reference numerals are given to the phase diagrams or the corresponding portions, and the repeated description thereof is omitted.

在本發明的一實施形態的雷射加工方法,藉由沿著切斷預定線,對加工對象物照射雷射光,沿著切斷預定線,在加工對象物的內部形成改質區域。因此,首先,針對此改質區域的形成,參照圖1~圖6進行說明。 In the laser processing method according to the embodiment of the present invention, the object to be processed is irradiated with laser light along the line to be cut, and a modified region is formed inside the object to be processed along the line to be cut. Therefore, first, the formation of this modified region will be described with reference to FIGS. 1 to 6 .

如圖1所示,雷射加工裝置100具備有:將雷射光L進行脈衝發振之雷射光源101;配置成將雷射光L的光軸(光路)的方向改變90°之分光鏡103;及用來將雷射光L予以聚光之聚光用透鏡105。又,雷射加工裝置100具備有:用來支承要照射以聚光用透鏡105所聚光的雷射光L之加工對象物1的支承台107;用來使支承台107移動之工作台111;控制雷射光源101,來調節雷射光L的輸出、脈衝寬度等之雷射光源控制部102;及控制工作台111的移動之工作台控制部115。 As shown in Fig. 1, the laser processing apparatus 100 includes: a laser light source 101 that pulsates the laser light L, and a beam splitter 103 that is arranged to change the direction of the optical axis (optical path) of the laser light L by 90[deg.] And a collecting lens 105 for collecting the laser light L. Further, the laser processing apparatus 100 includes a support base 107 for supporting the object 1 to be irradiated with the laser light L collected by the collecting lens 105, and a table 111 for moving the support table 107; The laser light source control unit 102 that controls the laser light source 101 to adjust the output of the laser light L, the pulse width, and the like, and the table control unit 115 that controls the movement of the table 111.

在此雷射加工裝置100,從雷射光源101所射出的雷射光L係藉由分光鏡103,將其光軸的方向改變90°,藉 由聚光用透鏡105聚光於載置在支承台107上之加工對象物1的內部。與此同時,使工作台111移動,讓加工對象物1對雷射光L,沿著切斷預定線5相對移動。藉此,將沿著切斷預定線5之改質區域形成在工對象物1。 In the laser processing apparatus 100, the laser light L emitted from the laser light source 101 is changed by the beam splitter 103 by 90° in the direction of the optical axis. The condensing lens 105 condenses the inside of the object 1 placed on the support table 107. At the same time, the table 111 is moved, and the object 1 is moved relative to the laser beam L along the line to cut 5 . Thereby, the modified region along the line to cut 5 is formed in the object 1 .

如圖2所示,在加工對象物1,設定有用來切斷加工對象物1之切斷預定線5。切斷預定線5為呈直線狀延伸之虛擬線。當在加工對象物1的內部形成改質區域時,如圖3所示,在使聚光點P對位加工對象物1的內部之狀態下,讓雷射光L沿著切斷預定線5(即,沿著圖2的箭號A方向)相對地移動。藉此,如圖4~圖6所示,將改質區域7沿著切斷預定線5形成於加工對象物1的內部,使得沿著切斷預定線5所形成的改質區域7成為切斷起點區域8。 As shown in FIG. 2, in the object 1 to be processed, a planned cutting line 5 for cutting the object 1 is set. The line to cut 5 is a virtual line extending in a straight line. When a modified region is formed inside the object 1 as shown in FIG. 3, the laser beam L is placed along the line to cut 5 in a state where the light-converging point P is aligned with the inside of the object 1 ( That is, it moves relatively along the arrow A direction of FIG. 2). As a result, as shown in FIGS. 4 to 6 , the modified region 7 is formed inside the object 1 along the line to cut 5 so that the modified region 7 formed along the line to cut 5 is cut. Break starting point area 8.

再者,聚光點P係指雷射光L聚光的部位。又,切斷預定線5不限於直線狀,亦可為曲線狀,又,不限於虛擬線,亦可為實際畫在加工對象物1的表面3之線。又,改質區域7,有為連續地形成之情況,亦有斷續地形成之情況。又,改質區域7可為列狀,亦可為點狀,也就是,改質區域7至少形成在加工對象物1的內部即可。又,會有以改質區域7作為起點來形成龜裂之情況,龜裂及改質區域7亦可露出於加工對象物1的外表面(表面、裏面、或外周面)。 Further, the condensed spot P is a portion where the laser light L is condensed. Further, the line to cut 5 is not limited to a straight line, and may be curved, and is not limited to a virtual line, and may be a line actually drawn on the surface 3 of the object 1 to be processed. Further, the modified region 7 may be formed continuously or intermittently. Further, the modified region 7 may be in a column shape or a dot shape, that is, the modified region 7 may be formed at least inside the object 1 to be processed. Further, the crack may be formed by using the modified region 7 as a starting point, and the crack and the modified region 7 may be exposed on the outer surface (surface, inner surface, or outer peripheral surface) of the object 1 to be processed.

順便一提,在此的雷射光L係透過加工對象物1,並且特別是在加工對象物1的內部的聚光點附近被吸收,藉 此,在加工對象物1形成改質區域7(即,內部吸收型雷射加工)。因此,因在加工對象物1的表面3,雷射光L幾乎未被吸收,所以不會有加工對象物1的表面3熔融之情況產生。一般,在從表面3進行熔融去除而形成孔、溝等的去除部之(表面吸收型雷射加工)情況,加工區域係自表面3側逐漸朝裏面側行進。 By the way, the laser light L transmitted here passes through the object 1 and is absorbed especially in the vicinity of the spot where the object 1 is processed. Thereby, the modified region 7 is formed in the object 1 (that is, internal absorption type laser processing). Therefore, since the laser light L is hardly absorbed on the surface 3 of the object 1 to be processed, the surface 3 of the object 1 does not melt. In general, in the case where the surface 3 is melted and removed to form a removal portion such as a hole or a groove (surface absorption type laser processing), the processing region gradually proceeds from the surface 3 side toward the back side.

又,在本實施形態所形成的改質區域係指密度、折射率、機械性強度、其他的物理的特性等與周圍不同之狀態的區域。作為改質區域,例如有熔融處理區域、龜裂區域、絕緣破壞區域、折射率變化區域等,亦有這些區域混合存在之區域。且,作為改質區域,具有在加工對象物的材料,與非改質區域的密度相比較,改質區域的密度會改變之區域、形成有格子缺陷的區域等(亦將這些區域總稱為高密度移轉區域)。 Further, the modified region formed in the present embodiment means a region having a state different from the surroundings such as density, refractive index, mechanical strength, and other physical properties. The modified region includes, for example, a molten processed region, a cracked region, an insulating fracture region, a refractive index change region, and the like, and a region in which these regions are mixed. Further, as the modified region, there is a region in which the density of the modified region is changed, a region in which the lattice defect is formed, and the like in the material of the object to be processed, compared with the density of the non-modified region (the regions are also collectively referred to as high Density transfer area).

又,熔融處理區域、折射率變化區域、與非改質區域的密度相比較,改質區域的密度會改變之區域、形成有格子缺陷的區域,進一步會有在這些區域的內部、改質區域等與非改質區域之界面,內包有龜裂(裂痕、微龜裂)之情況。內包之龜裂,係會有形成於改質區域的全面之情況、僅形成於一部分或複數部分之情況。 Further, in the molten processed region, the refractive index change region, and the density of the non-modified region, the region where the density of the modified region changes, the region in which the lattice defect is formed, and the modified region in the region The interface between the non-modified region and the non-modified region is covered with cracks (fractures, micro-cracks). The crack in the inner package may be formed in a comprehensive state of the modified region, and may be formed only in a part or a plurality of portions.

又,在本實施形態,藉由沿著切斷預定線5形成複數個改質點(加工痕),形成改質區域7。改質點係指以脈衝雷射光的1脈衝的射擊(即,1脈衝的雷射照射:雷射射擊)所形成的改質部分,藉由改質點聚集,而成為改質 區域7。作為改質點,可舉出龜裂點、熔融處理點或折射率變化點、或這些點中的至少一個混合存在者等。 Further, in the present embodiment, the modified region 7 is formed by forming a plurality of modified spots (machining marks) along the line to cut 5 . The modified point refers to the modified part formed by the pulse of 1 pulse of pulsed laser light (ie, 1 pulse of laser irradiation: laser shooting), which is modified by the aggregation of the modified spots. Area 7. Examples of the modification point include a crack point, a melting treatment point, or a refractive index change point, or a mixture of at least one of these points.

針對此改質點,考量所要求的切斷精度、所要求的切斷面的平坦性、加工對象物的厚度、種類、結晶方位等,適宜地控制其大小、所產生的龜裂之長度等為佳。 For this modification point, the cutting accuracy required, the required flatness of the cut surface, the thickness, type, and crystal orientation of the object to be processed are appropriately measured, and the size and the length of the crack generated are appropriately controlled. good.

其次,詳細地說明關於本發明的一實施形態的雷射加工方法。如圖7所示,加工對象物1為具備SiC基板12之圓形板狀(例如直徑3英吋、厚度350μm)的晶圓。如圖8所示,SiC基板12係具有六方晶系的結晶構造,其結晶軸CA係對SiC基板12的厚度方向傾斜角度θ(例如4°)。即,SiC基板12為具有角度θ的斜角之六方晶系SiC基板。如圖9所示,SiC基板12係具有與c面呈斜角分量的角度θ之表面(主面)12a及裏面(主面)12b。在SiC基板12,a面係對SiC基板12的厚度方向(圖中的兩點鎖線)傾斜著角度θ,m面係對SiC基板12的厚度方向未傾斜。 Next, a laser processing method according to an embodiment of the present invention will be described in detail. As shown in FIG. 7, the object 1 is a wafer having a circular plate shape (for example, a diameter of 3 inches and a thickness of 350 μm) including the SiC substrate 12. As shown in FIG. 8, the SiC substrate 12 has a hexagonal crystal structure, and the crystal axis CA is inclined by an angle θ (for example, 4°) with respect to the thickness direction of the SiC substrate 12. That is, the SiC substrate 12 is a hexagonal SiC substrate having an oblique angle of an angle θ. As shown in FIG. 9, the SiC substrate 12 has a surface (main surface) 12a and an inner surface (main surface) 12b having an angle θ which is an oblique component to the c-plane. In the SiC substrate 12, the a-plane is inclined at an angle θ with respect to the thickness direction of the SiC substrate 12 (two-point lock line in the drawing), and the m-plane is not inclined to the thickness direction of the SiC substrate 12.

如圖7及圖9所示,在加工對象物1,朝與表面12a及a面呈平行的方向延伸之複數條切斷預定線(第1切斷預定線)5a和朝與表面12a及m面呈平行的方向延伸之複數條切斷預定線(第2切斷預定線)5m係被設定成格子狀(例如1mm×1mm)。在SiC基板12的表面12a,於每個藉由切斷預定線5a、5m所區劃之區域,形成有功能元件,在SiC基板12的裏面12b,於每個藉由切斷預定線5a、5m所區劃之區域,形成有金屬配線。功能元件及 金屬配線係在藉由沿著切斷預定線5a、5m切斷加工對象物1所獲得之各晶圓,構成功率元件。再者,在SiC基板12,於與切斷預定線5a呈平行的方向,形成有定向平面6a,而與切斷預定線5m呈平行的方向,形成有定向平面6m。 As shown in FIG. 7 and FIG. 9, in the object 1 to be processed, a plurality of planned cutting lines (first cutting planned lines) 5a and facing surfaces 12a and m extending in a direction parallel to the surface 12a and the a surface are formed. The plurality of predetermined line cutting lines (second cutting planned lines) extending in the parallel direction are set to have a lattice shape (for example, 1 mm × 1 mm). On the surface 12a of the SiC substrate 12, functional elements are formed in each of the regions defined by the cutting planned lines 5a, 5m, and the inside of the SiC substrate 12 12b is cut by each of the predetermined lines 5a, 5m. The area to be zoned is formed with metal wiring. Functional components and The metal wiring is a power element formed by cutting each wafer obtained by cutting the object 1 along the cutting planned lines 5a and 5m. Further, in the SiC substrate 12, the orientation flat surface 6a is formed in a direction parallel to the line to cut 5a, and the orientation flat surface 6m is formed in a direction parallel to the line to cut 5m.

將以上的加工對象物1沿著切斷預定線5a、5m以下述的方式予以切斷。首先,如圖10所示,對加工對象物1黏貼擴展帶23,用以覆蓋SiC基板12的裏面12b的金屬配線。接著,如圖11(a)所示,將以20ns~100ns的脈衝寬度(更理想為50ns~60ns的脈衝寬度)進行了脈衝發振之雷射光L的聚光點P與SiC基板12的內部對位,以脈衝間距成為10μm~18μm(更理想為脈衝間距成為12μm~14μm)的方式,沿著切斷預定線5a對加工對象物1照射雷射光L。藉此,沿著切斷預定線5a,將作為切斷起點的改質區域(第1改質區域)7a形成於SiC基板12的內部。此改質區域7a係包含熔融處理區域。再者,脈衝間距係指「雷射光L的聚光點P對加工對象物1的移動速度」除以「脈衝雷射光L的重複頻率(repeating frequency)」之值。 The above-described object 1 is cut along the line to cut 5a, 5m in the following manner. First, as shown in FIG. 10, the extension tape 23 is adhered to the object 1 for covering the metal wiring of the back surface 12b of the SiC substrate 12. Next, as shown in FIG. 11(a), the condensed spot P of the laser light L pulse-oscillated with a pulse width of 20 ns to 100 ns (more preferably, a pulse width of 50 ns to 60 ns) and the inside of the SiC substrate 12 are formed. In the alignment, the object 1 is irradiated with the laser light L along the line to cut 5a so that the pulse pitch is 10 μm to 18 μm (more preferably, the pulse pitch is 12 μm to 14 μm). Thereby, the modified region (first modified region) 7a as the cutting start point is formed inside the SiC substrate 12 along the line to cut 5a. This modified region 7a contains a molten processed region. In addition, the pulse pitch means the value of "the moving speed of the condensed point P of the laser light L to the object 1 to be processed" divided by the "repeating frequency of the pulsed laser light L".

針對改質區域7a的形成,更詳細而言,以SiC基板12的表面12a作為雷射光射入面,使雷射光L的聚光點P位於SiC基板12的內部,沿著切斷預定線5a使聚光點P相對地移動。然後,將沿著切斷預定線5a之聚光點P的相對移動對1條切斷預定線5進行複數次(例如8次)。 此時,藉由在各次改變從表面12a到聚光點P的位置為止之距離,以排列於SiC基板12的厚度方向的方式,對1條切斷預定線5a形成複數列(第1列數、例如8列)的改質區域7a。在此,以與SiC基板12的作為雷射光射入面之表面12a第二接近的改質區域7a成為較與表面12a最接近的改質區域7a變小的方式,從SiC基板12的裏面12b側依序地(即,依距離雷射光射入面遠的順序)形成改質區域7a。再者,改質區域7a的大小係可藉由改變雷射光L的脈衝能量來進行調節。 In order to form the modified region 7a, the surface 12a of the SiC substrate 12 is used as a laser light incident surface, and the light collecting point P of the laser light L is positioned inside the SiC substrate 12 along the line to cut 5a. The light collecting point P is relatively moved. Then, the relative movement of the condensed spot P along the line to cut 5a is applied to the one line to cut 5 a plurality of times (for example, eight times). At this time, a plurality of columns (first column) are formed on one planned cutting line 5a so as to be arranged in the thickness direction of the SiC substrate 12 by changing the distance from the surface 12a to the position of the light collecting point P. A modified region 7a of a number, for example, 8 columns). Here, the modified region 7a which is second closest to the surface 12a of the SiC substrate 12 as the laser light incident surface is smaller than the modified region 7a closest to the surface 12a, and is formed from the inner surface 12b of the SiC substrate 12. The modified regions 7a are formed side by side (i.e., in a sequence far from the incident surface of the laser light). Furthermore, the size of the modified region 7a can be adjusted by changing the pulse energy of the laser light L.

藉此,從各改質區域7a所產生的龜裂會朝SiC基板12的厚度方向伸展而相互地連結。特別是從與SiC基板12的雷射光射入面之表面12a最接近的改質區域7a朝SiC基板12的厚度方向伸展之龜裂作成為到達表面12a。這些情事在將具有僅次於鑽石的硬度之由難加工材料所構成的SiC基板12沿著切斷預定線5a精度良好地予以切斷上,極為重要。 Thereby, the cracks generated from the respective modified regions 7a extend toward the thickness direction of the SiC substrate 12 and are connected to each other. In particular, the crack extending from the modified region 7a closest to the surface 12a of the laser light incident surface of the SiC substrate 12 toward the thickness direction of the SiC substrate 12 serves as the reaching surface 12a. In these cases, it is extremely important to accurately cut the SiC substrate 12 composed of a hard-to-machine material having a hardness second only to the diamond along the line to cut 5a.

在沿著切斷預定線5a形成改質區域7a後,如圖11(b)所示,將以20ns~100ns的脈衝寬度(更理想為50ns~60ns的脈衝寬度)進行了脈衝發振之雷射光L的聚光點P與SiC基板12的內部對位,以脈衝間距成為10μm~18μm(更理想為脈衝間距成為12μm~14μm)的方式,沿著切斷預定線5m對加工對象物1照射雷射光L。藉此,沿著切斷預定線5m,將作為切斷起點的改質區域(第2改質區域)7m形成於SiC基板12的內部。此改 質區域7m係包含熔融處理區域。 After the modified region 7a is formed along the line to cut 5a, as shown in FIG. 11(b), the pulse is pulsed with a pulse width of 20 ns to 100 ns (more preferably, a pulse width of 50 ns to 60 ns). The condensed spot P of the illuminating light L is aligned with the inside of the SiC substrate 12, and the object to be processed 1 is irradiated along the line to cut 5m so that the pulse pitch is 10 μm to 18 μm (more preferably, the pulse pitch is 12 μm to 14 μm). Laser light L. Thereby, a modified region (second modified region) 7m as a cutting start point is formed inside the SiC substrate 12 along the line to cut 5m. This change The mass region 7m contains a molten processed region.

針對改質區域7m的形成,更詳細而言,以SiC基板12的表面12a作為雷射光射入面,使雷射光L的聚光點P位於SiC基板12的內部,沿著切斷預定線5m使聚光點P相對地移動。然後,將沿著切斷預定線5m之聚光點P的相對的移動對1條切斷預定線5進行複數次(例如6次)。此時,藉由在各次改變從表面12a到聚光點P的位置為止之距離,以排列於SiC基板12的厚度方向的方式,對1條切斷預定線5m形成複數列(較第1列數少之第2列數(包含1列的情況)、例如6列)的改質區域7m。在此,以從與SiC基板12的雷射光射入面之表面12a最接近的改質區域7m成為較與第二接近表面12a之改質區域7m小的方式,從SiC基板12的裏面12b側依序地(即,依距離雷射光射入面遠的順序)形成改質區域7m。再者,改質區域7m的大小係可藉由改變雷射光L的脈衝能量來進行調節。 In the formation of the modified region 7m, more specifically, the surface 12a of the SiC substrate 12 is used as a laser light incident surface, and the light collecting point P of the laser light L is positioned inside the SiC substrate 12, along the line to cut 5m. The light collecting point P is relatively moved. Then, the relative movement of the condensed spot P along the line to cut 5m is performed for a plurality of predetermined lines 5 (for example, six times). At this time, by dividing the distance from the surface 12a to the position of the light-converging point P in each direction, a plurality of rows are formed on one planned cutting line 5m so as to be arranged in the thickness direction of the SiC substrate 12 (relative to the first The modified region 7m of the second column number (including one column), for example, six columns with a small number of columns. Here, the modified region 7m closest to the surface 12a of the laser light incident surface of the SiC substrate 12 is smaller than the modified region 7m of the second proximity surface 12a, and is formed from the inner surface 12b side of the SiC substrate 12. The modified region 7m is formed sequentially (i.e., in a sequence far from the incident surface of the laser light). Furthermore, the size of the modified region 7m can be adjusted by changing the pulse energy of the laser light L.

藉此,從各改質區域7m所產生之龜裂會朝SiC基板12的厚度方向伸展而相互地連結。特別是從與SiC基板12的雷射光射入面之表面12a最接近的改質區域7m朝SiC基板12的厚度方向伸展之龜裂作成為到達表面12a。這些情事在將具有僅次於鑽石的硬度之由難加工材料所構成的SiC基板12沿著切斷預定線5m精度良好地予以切斷上,極為重要。 Thereby, the cracks generated from the respective modified regions 7m are extended toward the thickness direction of the SiC substrate 12 and are connected to each other. In particular, the crack extending from the modified region 7m closest to the surface 12a of the laser light incident surface of the SiC substrate 12 toward the thickness direction of the SiC substrate 12 serves as the reaching surface 12a. In these cases, it is extremely important to accurately cut the SiC substrate 12 composed of a hard-to-machine material having a hardness second only to the diamond along the line to cut 5m.

在沿著切斷預定線5m形成改質區域7m後,如圖12 (a)所示,使擴展帶23擴張,在該狀態下,經由擴展帶23,對SiC基板12的裏面12b,沿著各切斷預定線5m推壓刀緣41。藉此,以改質區域7m作為起點而沿著切斷預定線5m,將加工對象物1切斷成桿狀。此時,由於擴展帶23處於被擴張之狀態,故,如圖12(b)所示,被切斷成桿狀之加工對象物1相互地分離著。 After the modified region 7m is formed along the cut line 5m, as shown in FIG. (a), the expansion tape 23 is expanded, and in this state, the blade edge 41 is pressed against the inner surface 12b of the SiC substrate 12 along the respective cutting planned lines 5m via the extension tape 23. Thereby, the object 1 to be processed is cut into a rod shape along the line to cut 5m with the modified region 7m as a starting point. At this time, since the extension belt 23 is in a state of being expanded, as shown in FIG. 12(b), the objects 1 to be cut into a rod shape are separated from each other.

在沿著切斷預定線5m切斷加工對象物1後,如圖13(a)所示,接著在擴展帶23已被擴張之狀態下,經由擴展帶23,對SiC基板12的裏面12b,沿著各切斷預定線5a推壓刀緣41。藉此,以改質區域7a作為起點,沿著切斷預定線5a將加工對象物1切斷成晶片狀。此時,由於擴展帶23處於被擴張之狀態,故,如圖13(b)所示,已被切斷成晶片狀之加工對象物1成為相互分離。如以上所述,加工對象物1沿著切斷預定線5a、5m被切斷成晶片狀,而獲得多數個功率元件。 After the object 1 is cut along the line to cut 5m, as shown in FIG. 13(a), the inner side 12b of the SiC substrate 12 is then passed through the extension tape 23 while the extension tape 23 has been expanded. The blade edge 41 is pressed along each of the planned cutting lines 5a. Thereby, the object to be processed 1 is cut into a wafer shape along the line to cut 5a with the modified region 7a as a starting point. At this time, since the extension belt 23 is in a state of being expanded, as shown in FIG. 13(b), the objects 1 to be cut into a wafer shape are separated from each other. As described above, the object 1 is cut into a wafer shape along the line to cut 5a, 5m, and a plurality of power elements are obtained.

若依據以上的雷射加工方法,依據以下的理由,可將具備具有與c面呈斜角分量的角度之表面12a的六方晶系SiC基板12之板狀加工對象物1沿著切斷預定線5a、5m精度良好地予以切斷,其結果,能夠獲得沿著切斷預定線5a、5m被精度良好地切斷之加工對象物1(即,功率元件)。 According to the above-described laser processing method, the plate-shaped object 1 having the hexagonal SiC substrate 12 having the surface 12a having an angle of an oblique angle to the c-plane can be along the line to be cut. 5a and 5m are cut off with high precision, and as a result, the object 1 (i.e., power element) that is accurately cut along the line to cut 5a, 5m can be obtained.

首先,以脈衝間距成為10μm~18μm的方式,沿著切斷預定線5a、5m對加工對象物1照射雷射光L。當在這樣的條件下對加工對象物1照射雷射光L時,可使龜裂 容易從改質區域7a、7m朝SiC基板12的厚度方向伸展,而讓龜裂不易從改質區域7a、7m朝c面方向伸展。且,以脈衝間距成為12μm~14μm的方式,沿著切斷預定線5a、5m對加工對象物1照射雷射光L的話,則能夠進一步使龜裂從改質區域7a、7m朝SiC基板12的厚度方向伸展,而讓龜裂不易從改質區域7a、7m朝c面方向伸展。 First, the object 1 is irradiated with the laser light L along the line to cut 5a, 5m so that the pulse pitch is 10 μm to 18 μm. When the object 1 is irradiated with the laser light L under such conditions, cracking can be caused. It is easy to extend from the modified regions 7a and 7m in the thickness direction of the SiC substrate 12, and it is difficult for the crack to extend from the modified regions 7a and 7m toward the c-plane direction. In addition, when the laser beam L is irradiated to the object 1 along the line to cut 5a and 5m so that the pulse pitch is 12 μm to 14 μm, the crack can be further moved from the modified regions 7a and 7m toward the SiC substrate 12. The thickness direction is extended, and the crack is not easily extended from the modified regions 7a, 7m toward the c-plane.

又,以20ns~100ns的脈衝寬度使雷射光L進行脈衝發振。藉此,能夠使龜裂從改質區域7a、7m朝SiC基板12的厚度方向容易確實地伸展,而讓龜裂確實地不易從改質區域7a、7m朝c面方向伸展。且,若以50ns~60ns的脈衝寬度使雷射光L進行脈衝發振的話,則可更確實且容易地使龜裂從改質區域7a、7m朝SiC基板12的厚度方向伸展,而讓龜裂更確實且不容易地從改質區域7a、7m朝c面方向伸展。 Further, the laser light L is pulse-oscillated with a pulse width of 20 ns to 100 ns. Thereby, the crack can be easily and reliably extended from the modified regions 7a and 7m toward the thickness direction of the SiC substrate 12, and the cracks are reliably prevented from extending from the modified regions 7a and 7m toward the c-plane direction. Further, when the laser light L is pulse-oscillated with a pulse width of 50 ns to 60 ns, the crack can be more reliably and easily extended from the modified regions 7a and 7m toward the thickness direction of the SiC substrate 12, and the crack is allowed to be cracked. It is more sure and not easy to extend from the modified regions 7a, 7m toward the c-plane direction.

又,沿著切斷預定線5a,將與SiC基板12的作為雷射光射入面之表面12a第二接近的改質區域7a相對地形成較小。藉此,即使a面對SiC基板12的厚度方向傾斜,也能夠防止:從與第二接近表面12a之改質區域7a所產生的龜裂朝a面方向伸展而在自切斷預定線5a大幅地偏移的狀態下到達表面12a的情況產生。然後,沿著切斷預定線5a,使與SiC基板12的雷射光射入面之表面12a最接近的改質區域7a相對地形成較大。藉此,雖從改質區域7a,處於龜裂不易朝SiC基板12的厚度方向伸展之 狀態,但,能夠使龜裂從與表面12a最接近的改質區域7a確實地到達表面12a。又,沿著切斷預定線5m,使與SiC基板12的作為雷射光射入面之表面12a第二接近的改質區域7m相對地形成較大。藉此,從改質區域7m,處於龜裂容易朝SiC基板12的厚度方向伸展之狀態,與此相輔相成,能讓從與第二接近表面12a之改質區域7m所產生之龜裂到達表面12a或其附近。然後,沿著切斷預定線5m,將與SiC基板12的雷射光射入面之表面12a最接近的改質區域7m相對地形成較小。藉此,既可防止在表面12a產生損傷,又,能使龜裂從改質區域7m確實地到達表面12a。如以上所述,沿著切斷預定線5a,能夠讓龜裂從改質區域7a確實地到達表面12a,又,沿著切斷預定線5m,能使龜裂從改質區域7m確實地到達表面12a。這個效果係與後述的改質區域7a、7m的形成列、形成順序等無關連即可達到,當依據後述的改質區域7a、7m的形成列、形成順序時,更顯著。 Further, along the line to cut 5a, the modified region 7a which is second closest to the surface 12a of the SiC substrate 12 as the laser light incident surface is formed to be relatively small. By this, even if a is inclined in the thickness direction of the SiC substrate 12, it is possible to prevent the crack generated from the modified region 7a of the second proximity surface 12a from extending in the a-plane direction and being largely large in the self-cutting line 5a. The situation of reaching the surface 12a in the state of the ground offset occurs. Then, along the line to cut 5a, the modified region 7a closest to the surface 12a of the laser light incident surface of the SiC substrate 12 is formed to be relatively large. Thereby, the crack is hard to extend toward the thickness direction of the SiC substrate 12 from the modified region 7a. In the state, the crack can be surely reached from the modified region 7a closest to the surface 12a to the surface 12a. Moreover, along the line to cut 5m, the modified region 7m which is second closest to the surface 12a of the SiC substrate 12 as the laser light incident surface is formed to face large. Thereby, the modified region 7m is in a state where the crack easily spreads in the thickness direction of the SiC substrate 12, and complements this, and the crack generated from the modified region 7m of the second proximity surface 12a can be brought to the surface 12a. Or nearby. Then, along the line to cut 5m, the modified region 7m closest to the surface 12a of the laser light incident surface of the SiC substrate 12 is formed to be relatively small. Thereby, damage to the surface 12a can be prevented, and the crack can be surely reached from the modified region 7m to the surface 12a. As described above, along the line to cut 5a, the crack can be surely reached from the modified region 7a to the surface 12a, and along the line to cut 5m, the crack can be surely reached from the modified region 7m. Surface 12a. This effect can be achieved irrespective of the formation order of the modified regions 7a and 7m to be described later, the order of formation, and the like, and is more remarkable in the order of formation and formation of the modified regions 7a and 7m to be described later.

又,比起沿著1條切斷預定線5m形成改質區域7m之情況,沿著1條切斷預定線5a,形成較多列數的改質區域7a。藉此,即使a面對SiC基板12的厚度方向傾斜,當各改質區域7a的形成時,既可防止龜裂從改質區域7a朝a面方向大幅地伸展,又,在所有的改質區域7a間,能夠作成為龜裂在SiC基板12的厚度方向容易連結之狀態。又,比起沿著1條切斷預定線5a形成改質區域7a之情況,沿著1條切斷預定線5m,形成較少列數的改質 區域7m。藉此,當各自的改質區域7m的形成時,能夠使龜裂從改質區域7m朝SiC基板12的厚度方向大幅地伸展。如以上所述,沿著切斷預定線5a,能夠使龜裂從改質區域7a朝SiC基板12的厚度方向伸展,又,沿著切斷預定線5m,能夠使龜裂從改質區域7m朝SiC基板12的厚度方向伸展。這個效果係與前述的改質區域7a、7m的形成尺寸、後述的改質區域7a、7m的形成順序無關連而能夠達到,當依據前述的改質區域7a、7m的形成尺寸、後述的改質區域7a、7m的形成順序時,則可更顯著地達到。 In addition, when the modified region 7m is formed along one planned cutting line 5m, the predetermined line 5a is cut along one strip to form a plurality of modified regions 7a. Thereby, even if a is inclined in the thickness direction of the SiC substrate 12, when the modified regions 7a are formed, it is possible to prevent the crack from being greatly extended from the modified region 7a toward the a-plane direction, and all the modifications are performed. Between the regions 7a, the cracks can be easily connected in the thickness direction of the SiC substrate 12. Moreover, compared with the case where the modified region 7a is formed along one planned cutting line 5a, the predetermined line 5m is cut along one strip to form a modified number of fewer rows. Area 7m. Thereby, when each of the modified regions 7m is formed, the crack can be greatly extended from the modified region 7m toward the thickness direction of the SiC substrate 12. As described above, along the line to cut 5a, the crack can be extended from the modified region 7a toward the thickness direction of the SiC substrate 12, and along the line to cut 5m, the crack can be made from the modified region 7m. It extends toward the thickness direction of the SiC substrate 12. This effect can be achieved irrespective of the formation dimensions of the modified regions 7a and 7m described above and the order of formation of the modified regions 7a and 7m to be described later, and the size of the modified regions 7a and 7m can be changed according to the above-described modified regions 7a and 7m. When the order of formation of the prime regions 7a, 7m is achieved, it can be more significantly achieved.

又,在形成用來使龜裂朝SiC基板12的厚度方向伸展之條件為和緩的改質區域7m之前,形成用來使龜裂朝SiC基板12的厚度方向伸展之條件為嚴苛之改質區域7a。藉此,當改質區域7a的形成時,在切斷預定線5a與切斷預定線5m交叉之部分,能夠防止龜裂自改質區域7a朝SiC基板12的厚度方向的伸展被改質區域7m所阻礙之情況產生。這個效果係與前述的改質區域7a、7m的形成尺寸、形成列等無關連即可達到。 Further, before the conditions for forming the crack to extend in the thickness direction of the SiC substrate 12 are the gentle modified regions 7m, the conditions for stretching the cracks in the thickness direction of the SiC substrate 12 are severely modified. Area 7a. With this, when the modified region 7a is formed, the portion where the planned cutting line 5a intersects the planned cutting line 5m can prevent the crack from extending from the modified region 7a toward the thickness direction of the SiC substrate 12 by the modified region. The situation hindered by 7m. This effect can be achieved irrespective of the formation size, formation of columns, and the like of the modified regions 7a and 7m described above.

且,以改質區域7m作為起點而沿著切斷預定線5m,切斷加工對象物1,之後,以改質區域7a作為起點,沿著切斷預定線5a切斷加工對象物1。藉此,藉由較少列數的改質區域7m的形成,沿著想定成較難切斷之切斷預定線5m,切斷加工對象物1,之後,再藉由較多列數的改質區域7a的形成,沿著想定成較容易切斷之切斷預 定線5a,切斷加工對象物1。因此,能夠將沿著切斷預定線5m切斷加工對象物1所需要的力與沿著切斷預定線5a切斷加工對象物1所需要的力予以均等化,可將沿著切斷預定線5m之切斷精度與沿著切斷預定線5a之切斷精度皆進一步提升。這個效果係與前述的改質區域7a、7m的形成尺寸、形成列等無關連即可達到。 In addition, the object 1 is cut along the line to cut 5m as the starting point of the modified region 7m, and then the object 1 is cut along the line to cut 5a with the modified region 7a as a starting point. As a result, the object to be processed 1 is cut along the line 5m to be cut, which is difficult to cut, by the formation of the modified region 7m having a small number of rows, and then the number of columns is changed by a larger number of columns. The formation of the mass region 7a is determined along a cutting premise that is easier to cut. The object 5 is cut and the object 1 is cut. Therefore, it is possible to equalize the force required to cut the object 1 along the line to cut 5m and the force required to cut the object 1 along the line to cut 5a, and it is possible to follow the cutting schedule. The cutting accuracy of the line 5m and the cutting accuracy along the line to cut 5a are further improved. This effect can be achieved irrespective of the formation size, formation of columns, and the like of the modified regions 7a and 7m described above.

圖14係顯示藉由上述的雷射加工方法,沿著切斷預定線5a被切斷之SiC基板12的切斷面的照片的圖。又,圖15係顯示藉由上述的雷射加工方法,沿著切斷預定線5m被切斷之SiC基板12的切斷面的照片的圖。且,圖16係顯示藉由上述的雷射加工方法,沿著切斷預定線5a、5m被切斷之SiC基板12的切斷面的平面照片的圖。在此,準備具有4°的斜角之厚度350μm的六方晶系SiC基板12。 Fig. 14 is a view showing a photograph of a cut surface of the SiC substrate 12 cut along the line to cut 5a by the above-described laser processing method. Moreover, FIG. 15 is a view showing a photograph of the cut surface of the SiC substrate 12 cut along the line to cut 5m by the above-described laser processing method. Moreover, FIG. 16 is a plan view showing a cut surface of the cut surface of the SiC substrate 12 cut along the line to cut 5a, 5m by the above-described laser processing method. Here, a hexagonal SiC substrate 12 having a thickness of 4° and a thickness of 350 μm was prepared.

首先,如圖14所示,沿著切斷預定線5a,以排列於SiC基板12的厚度方向的方式,對1條切斷預定線5a形成8列的改質區域7a。然後,以與SiC基板12的作為雷射光射入面之表面12a第二接近的改質區域7a成為較與表面12a最接近的改質區域7a變小的方式,從SiC基板12的裏面12b側依序地形成改質區域7a。從圖14可得知,藉由與第二接近表面12a之改質區域7a的形成,從改質區域7a所產生之龜裂的伸展被停止。其結果,切斷面對切斷預定線5a的蛇行係如圖16所示,抑制在±4μm以下。 First, as shown in FIG. 14, eight rows of modified regions 7a are formed on one planned cutting line 5a so as to be aligned in the thickness direction of the SiC substrate 12 along the line to cut 5a. Then, the modified region 7a which is second closest to the surface 12a of the SiC substrate 12 as the laser light incident surface becomes smaller than the modified region 7a closest to the surface 12a, and is from the inner surface 12b side of the SiC substrate 12. The modified region 7a is sequentially formed. As can be seen from Fig. 14, the extension of the crack generated from the modified region 7a is stopped by the formation of the modified region 7a with the second proximity surface 12a. As a result, the meandering system that cuts the line to cut 5a is cut as shown in Fig. 16 and is suppressed to ±4 μm or less.

再者,從表面12a到聚光點P的位置為止的距離係從SiC基板12的裏面12b側的改質區域7a起依序為314.5μm、280.0μm、246.0μm、212.0μm、171.5μm、123.5μm、79.0μm、32.0μm。又,雷射光L的脈衝能量係從SiC基板12的裏面12b側的改質區域7a起依序為25μJ、25μJ、25μJ、25μJ、20μJ、15μJ、6μJ、6μJ。 In addition, the distance from the surface 12a to the position of the light-converging point P is 314.5 μm, 280.0 μm, 246.0 μm, 212.0 μm, 171.5 μm, and 123.5 in order from the modified region 7a on the inner surface 12b side of the SiC substrate 12. Μm, 79.0 μm, 32.0 μm. Further, the pulse energy of the laser light L is sequentially 25 μJ, 25 μJ, 25 μJ, 25 μJ, 20 μJ, 15 μJ, 6 μJ, and 6 μJ from the modified region 7 a on the back surface 12 b side of the SiC substrate 12 .

又,如圖15所示,沿著切斷預定線5m,以排列於SiC基板12的厚度方向的方式,對1條切斷預定線5m形成6列的改質區域7m。然後,以從與SiC基板12的雷射光射入面之表面12a最接近的改質區域7m成為較與第二接近表面12a之改質區域7m小的方式,從SiC基板12的裏面12b側依序地形成改質區域7m。從圖15可得知,藉由與第二接近表面12a之改質區域7m的形成,從改質區域7m所產生之龜裂伸展至表面12a或其附近。其結果,切斷面對切斷預定線5m的蛇行係如圖16所示,抑制在±2μm以下。 In addition, as shown in FIG. 15, the modified region 7m of six rows is formed on one planned cutting line 5m so as to be aligned in the thickness direction of the SiC substrate 12 along the line to cut 5m. Then, the modified region 7m closest to the surface 12a of the laser light incident surface of the SiC substrate 12 is smaller than the modified region 7m of the second proximity surface 12a, and is supported from the inner surface 12b side of the SiC substrate 12. The modified region 7m is sequentially formed. As can be seen from Fig. 15, the crack generated from the modified region 7m extends to the surface 12a or its vicinity by the formation of the modified region 7m with the second proximity surface 12a. As a result, the meandering system that cuts the line 5m to be cut is cut as shown in Fig. 16 and is suppressed to ±2 μm or less.

再者,從表面12a到聚光點P的位置為止的距離係從SiC基板12的裏面12b側的改質區域7m起依序為315.5μm、264.5μm、213.5μm、155.0μm、95.5μm、34.5μm。又,雷射光L的脈衝能量係從SiC基板12的裏面12b側的改質區域7m起依序為25μJ、25μJ、20μJ、20μJ、15μJ、7μJ。 In addition, the distance from the surface 12a to the position of the light-converging point P is 315.5 μm, 264.5 μm, 213.5 μm, 155.0 μm, 95.5 μm, and 34.5 in order from the modified region 7m on the inner surface 12b side of the SiC substrate 12. Mm. Further, the pulse energy of the laser light L is 25 μJ, 25 μJ, 20 μJ, 20 μJ, 15 μJ, and 7 μJ from the modified region 7 m on the inner surface 12 b side of the SiC substrate 12 .

其次,說明關於從改質區域7a、7m到達SiC基板12的雷射光射入面之表面12a之龜裂(以下,稱為「半切( half cut)」)與從改質區域7a、7m朝c面方向伸展之龜裂(以下,稱為「c面裂痕」)之關係。在此,如圖17及圖18所示,以在欲使龜裂朝SiC基板12的厚度方向伸展之情況,比起改質區域7m,更不易產生半切且也更不易產生c面裂痕之改質區域7a作為對象進行說明。 Next, the cracks on the surface 12a of the laser light incident surface that reaches the SiC substrate 12 from the modified regions 7a and 7m will be described (hereinafter, referred to as "half cut ( The relationship between the half cut) and the crack extending from the modified regions 7a and 7m toward the c-plane direction (hereinafter referred to as "c-plane crack"). Here, as shown in FIG. 17 and FIG. 18, in the case where the crack is to be extended in the thickness direction of the SiC substrate 12, the half-cut is less likely to occur and the c-plane crack is less likely to occur than the modified region 7m. The qualitative region 7a will be described as an object.

圖19係顯示脈衝寬度與ID閾值、HC閾值及加工裕度之關係的表。在此,使脈衝寬度在1ns、10ns~120ns的範圍改變,對每個脈衝寬度,進行ID閾值、HC閾值及加工裕度的評價。又,圖20係顯示脈衝間距與ID閾值、HC閾值及加工裕度之關係的表。在此,使脈衝間距在6μm~22μm的範圍改變,針對每個脈衝間距,進行ID閾值、HC閾值及加工裕度的評價。 Fig. 19 is a table showing the relationship between the pulse width and the ID threshold, the HC threshold, and the processing margin. Here, the pulse width is changed in the range of 1 ns and 10 ns to 120 ns, and the ID threshold, the HC threshold, and the processing margin are evaluated for each pulse width. 20 is a table showing the relationship between the pulse pitch and the ID threshold, the HC threshold, and the machining margin. Here, the pulse pitch was changed in the range of 6 μm to 22 μm, and the ID threshold, the HC threshold, and the processing margin were evaluated for each pulse pitch.

再者,ID閾值係指可使c面裂痕產生之雷射光L的脈衝能量的最小值,從ID閾值高者(即,不易產生c面裂痕者)依序評價為優、良、可、不可。又,HC閾值係指可使半切產生之雷射光L的脈衝能量的最小值,從HC閾值低者(即,容易產生半切者)依序評價為優、良、可、不可。且,加工裕度係指ID閾值與HC閾值之差,從加工裕度大者依序評價為優、良、可、不可。然後,總體係以ID閾值、HC閾值、加工裕度之優先順位進行衡量,評價為優、良、可、不可。 Furthermore, the ID threshold refers to the minimum value of the pulse energy of the laser light L that can cause the c-plane crack, and the one with the highest ID threshold (that is, the one that does not easily generate the c-plane crack) is evaluated as excellent, good, acceptable, and non-existent. . Further, the HC threshold value means the minimum value of the pulse energy of the laser light L which can be generated by half-cutting, and is preferably evaluated as excellent, good, and acceptable from the case where the HC threshold is low (that is, the half-cut is likely to occur). Moreover, the processing margin refers to the difference between the ID threshold and the HC threshold, and is evaluated as excellent, good, acceptable, and incapable from the processing margin. Then, the total system is measured by the priority of the ID threshold, the HC threshold, and the processing margin, and the evaluation is excellent, good, acceptable, and impossible.

其結果可得知,如圖19所示,以20ns~100ns的脈衝寬度使雷射光L進行脈衝發振為佳,以50ns~60ns的脈衝寬度使雷射光L進行脈衝發振為更佳。藉此,既可抑 制c面裂痕的產生,又可促進半切的產生。再者,在脈衝寬度為10ns之情況的ID閾值、加工裕度及總體的各評價係為比起脈衝寬度為20ns之情況,為接近不可之可的狀態。 As a result, as shown in FIG. 19, it is preferable that the laser light L is pulse-oscillated with a pulse width of 20 ns to 100 ns, and it is more preferable to pulse-raise the laser light L with a pulse width of 50 ns to 60 ns. By doing so, it can suppress The production of c-plane cracks can also promote the production of half-cuts. Further, in the case where the pulse width is 10 ns, the ID threshold value, the machining margin, and the overall evaluation are in a state in which the pulse width is 20 ns.

又,如圖20所示,可得知以脈衝間距成為10μm~18μm的方式,沿著切斷預定線5a、5m對SiC基板12照射雷射光L為佳,以脈衝間距成為11μm~15μm的方式,沿著切斷預定線5a、5m對SiC基板12照射雷射光L為更佳,且,以脈衝間距成為12μm~14μm的方式,沿著切斷預定線5a、5m對SiC基板12照射雷射光L為最佳。藉此,既可抑制c面裂痕的產生,又可促進半切的產生。再者,由於脈衝間距成為10μm時,ID閾值的評價為可,故,若更重視抑制c面裂痕的產生之情況,則脈衝間距較10μm大為更佳。 Further, as shown in FIG. 20, it is preferable that the SiC substrate 12 is irradiated with the laser light L along the line to cut 5a, 5m so that the pulse pitch is 11 μm to 15 μm, and the pulse pitch is 11 μm to 15 μm. It is preferable that the SiC substrate 12 is irradiated with the laser light L along the line to cut 5a, 5m, and the SiC substrate 12 is irradiated with laser light along the line to cut 5a, 5m so that the pulse pitch is 12 μm to 14 μm. L is the best. Thereby, the occurrence of c-plane cracks can be suppressed, and the generation of half-cuts can be promoted. Further, when the pulse pitch is 10 μm, the evaluation of the ID threshold is possible. Therefore, if it is more important to suppress the occurrence of the c-plane crack, the pulse pitch is preferably larger than 10 μm.

圖21~圖23係顯示以開口數0.8將雷射光L予以聚光的情況時之脈衝寬度及脈衝間距的加工裕度的實驗結果之表。這些實驗結果係成為圖19及圖20所示的評價之依據。獲得圖21~圖23的實驗結果時的實驗條件係如以下所示。。首先,以具有4°的斜角之厚度100μm的六方晶系SiC基板12作為對象,沿著朝與表面12a及a面呈平行的方向延伸之切斷預定線5a,使雷射光L的聚光點P移動。又,以開口數0.8將雷射光L予以聚光,使聚光點P對位於與SiC基板12的雷射光射入面之表面12a距離59μm的位置。 21 to 23 are tables showing experimental results of the processing margins of the pulse width and the pulse pitch when the laser light L is condensed by the number of openings 0.8. These experimental results are the basis for the evaluations shown in Figs. 19 and 20. The experimental conditions at the time of obtaining the experimental results of FIGS. 21 to 23 are as follows. . First, the hexagonal SiC substrate 12 having a thickness of 100 μm having an oblique angle of 4° is used as a target, and the laser beam L is concentrated along a line to cut 5a extending in a direction parallel to the surfaces 12a and a. Point P moves. Further, the laser beam L is condensed by the number of openings of 0.8, and the condensed spot P is positioned at a distance of 59 μm from the surface 12a of the laser light incident surface of the SiC substrate 12.

將以上的實驗條件作為前提,分別使雷射光L的能量(脈衝能量)及功率和雷射光L的脈衝間距改變,觀察改質區域7a以及半切及c面裂痕的狀態。在圖21~圖23中,分別將雷射光L的脈衝寬度作為27ns、40ns、57ns,而將雷射光L的脈衝寬度(重複頻率)作為10kHz、20kHz、35kHz。 On the premise of the above experimental conditions, the energy (pulse energy) of the laser light L and the pulse pitch of the laser light L are changed, and the state of the modified region 7a and the half-cut and c-plane cracks are observed. In FIGS. 21 to 23, the pulse width of the laser light L is set to 27 ns, 40 ns, and 57 ns, respectively, and the pulse width (repetition frequency) of the laser light L is set to 10 kHz, 20 kHz, and 35 kHz.

在圖21~圖23的實驗結果,ST係顯示未產生半切,HC係顯示有產生半切。又,ID係顯示有產生c面裂痕,LV1~LV3係顯示c面裂痕的產生規模。在分別沿著2條切斷預定線5a,形成改質區域7a之情況,將對40mm的區域(20mm×2條區域),c面裂痕的產生區域未滿150μm時設為LV1,將c面裂痕的產生區域未滿450μm時設為LV2,將c面裂痕的產生區域成為450μm以上時設為LV3。在LV1,朝與切斷預定線5a呈垂直的方向之c裂痕的伸展成為10μm~20μm,相對於此,在LV2,LV3,朝與切斷預定線5a呈垂直的方向之c裂痕的伸展成為最大之100μm左右。 In the experimental results of Figs. 21 to 23, the ST system showed no half cut, and the HC system showed half cut. Further, the ID system showed a c-plane crack, and the LV1 to LV3 system showed the scale of the c-plane crack. In the case where the modified region 7a is formed along the two predetermined lines 5a, the region of 40 mm (20 mm × 2 regions) is set to LV1 when the area where the c-plane crack is generated is less than 150 μm, and the c-plane is used. When the area where the crack is generated is less than 450 μm, LV2 is set, and when the area where the c-plane crack is generated is 450 μm or more, LV3 is used. In LV1, the extension of the c-crack in the direction perpendicular to the line to cut 5a is 10 μm to 20 μm, whereas in the case of LV2, LV3, the extension of the crack in the direction perpendicular to the line to cut 5a becomes The maximum is about 100μm.

圖24係顯示脈衝間距與HC閾值之關係的圖表。又,圖25係顯示脈衝間距與ID閾值之關係的圖表。且,圖26係顯示脈衝間距與加工裕度之關係的圖表。這些圖表係依據圖21~圖23的實驗結果所作成的。如圖24及圖25所示,當脈衝寬度變大時,HC閾值及ID閾值雙方均會上升,但,比起HC閾值的劣化(上昇),ID閾值的提升(上升)效果變大。這是如圖26所示,意味著當脈衝 寬度變大時,加工裕度變大。例如,在著眼於脈衝寬度27ns及脈衝寬度57ns之情況,當脈衝間距為12μm時,HC閾值係從15μJ劣化(上升)2μJ而形成為17μJ,相度於此ID閾值從17μJ提升(上升)12μJ而形成為29μJ。然後,在脈衝寬度40ns的情況,比起脈衝寬度27ns的情況,確認到在脈衝間距10μm~16μm的範圍下加工裕度的大幅提升。又,在脈衝寬度57ns的情況,比起脈衝寬度27ns的情況,確認到在脈衝間距6μm~20μm的範圍下加工裕度的大幅提昇。 Figure 24 is a graph showing the relationship between the pulse pitch and the HC threshold. 25 is a graph showing the relationship between the pulse pitch and the ID threshold. Moreover, Fig. 26 is a graph showing the relationship between the pulse pitch and the machining margin. These charts are based on the experimental results of Figures 21-23. As shown in FIG. 24 and FIG. 25, when the pulse width is increased, both the HC threshold value and the ID threshold value are increased. However, the effect of increasing (rising) the ID threshold value is larger than the deterioration (rise) of the HC threshold value. This is shown in Figure 26, meaning when the pulse When the width becomes larger, the machining margin becomes larger. For example, when focusing on a pulse width of 27 ns and a pulse width of 57 ns, when the pulse pitch is 12 μm, the HC threshold is deteriorated (rised) by 2 μJ from 15 μJ to 17 μJ, and the ID threshold is raised (rised) by 12 μJ from 17 μJ. The formation was 29 μJ. Then, in the case of a pulse width of 40 ns, it was confirmed that the processing margin was greatly improved in the range of the pulse pitch of 10 μm to 16 μm compared to the case where the pulse width was 27 ns. Further, in the case of a pulse width of 57 ns, it was confirmed that the processing margin was greatly improved in the range of the pulse pitch of 6 μm to 20 μm compared to the case where the pulse width was 27 ns.

圖27~圖29係顯示以開口數0.6將雷射光L予以聚光之情況的脈衝寬度及脈衝間距的加工裕度的實驗結果之表。這些實驗結果係成為圖19及圖20所示的評價之依據。圖27~圖29的實驗結果時的實驗條件係如以下所示。首先,以具有與c面呈斜角分量的角度之表面12a的厚度350μm的六方晶系SiC基板12作為對象,沿著朝與表面12a及a面呈平行的方向延伸之切斷預定線5a,使雷射光L的聚光點P移動。又,以開口數0.6將雷射光L予以聚光,將聚光點P對位於與SiC基板12的雷射光射入面之表面12a相距50μm的位置。 27 to 29 are tables showing experimental results of the processing margins of the pulse width and the pulse pitch in the case where the laser light L is condensed by the number of openings 0.6. These experimental results are the basis for the evaluations shown in Figs. 19 and 20. The experimental conditions at the experimental results of Figs. 27 to 29 are as follows. First, a hexagonal SiC substrate 12 having a thickness of 350 μm having a surface 12a having an oblique angle component to the c-plane is used as a target along a line to cut 5a extending in a direction parallel to the surfaces 12a and a, The condensing point P of the laser light L is moved. Further, the laser light L is condensed by the number of openings of 0.6, and the condensed spot P is located at a position of 50 μm from the surface 12a of the laser light incident surface of the SiC substrate 12.

將以上的實驗條件作為前提,分別使雷射光L的能量(脈衝能量)及功率和雷射光L的脈衝間距改變,觀察改質區域7a以及半切及c面裂痕的狀態。在圖27~圖29,分別將雷射光L的脈衝寬度作為27ns、40ns、57ns,而將雷射光L的脈衝寬度(重複頻率)作為10kHz、20kHz、 35kHz。 On the premise of the above experimental conditions, the energy (pulse energy) of the laser light L and the pulse pitch of the laser light L are changed, and the state of the modified region 7a and the half-cut and c-plane cracks are observed. In FIGS. 27 to 29, the pulse width of the laser light L is set to 27 ns, 40 ns, and 57 ns, respectively, and the pulse width (repetition frequency) of the laser light L is set to 10 kHz, 20 kHz, 35kHz.

在圖27~圖29的實驗結果,ST係顯示未產生半切,HC係顯示有產生半切。又,ID係顯示有產生c面裂痕,LV1~LV3係顯示c面裂痕的產生規模。LV1~LV3的基準係與上述的圖21~圖23的實驗結果的情況相同。且,OD係顯示當增大雷射光L的能量時,改質區域7a也變大,因為此原因所產生的龜裂會從切斷預定線5a大幅地偏移,而到達SiC基板12的表面12a。在此情況,未針對c面裂痕進行評價。但,在脈衝寬度40ns及脈衝寬度57ns,脈衝間距為12μm以上時,未產生大規模的c面裂痕。 In the experimental results of Figs. 27 to 29, the ST system showed no half cut, and the HC system showed half cut. Further, the ID system showed a c-plane crack, and the LV1 to LV3 system showed the scale of the c-plane crack. The reference system of LV1 to LV3 is the same as the experimental results of FIGS. 21 to 23 described above. Further, the OD system shows that when the energy of the laser light L is increased, the modified region 7a also becomes large, because the crack generated for this reason is largely shifted from the line to cut 5a to reach the surface of the SiC substrate 12. 12a. In this case, no evaluation was made for the c-plane crack. However, when the pulse width is 40 ns and the pulse width is 57 ns, and the pulse pitch is 12 μm or more, large-scale c-plane cracks are not generated.

圖30係顯示脈衝間距與HC閾值之關係的圖表。此圖表係依據圖27~圖29的實驗結果所作成的。如圖30所示,在脈衝寬度57ns的情況,比起脈衝寬度40ns的情況,HC閾值為2μJ~4μJ左右不易產生。比起上述的開口數0.8的情況,在開口數0.6的情況,由於在雷射光L的聚光點P,收差的影響變小,故,在脈衝寬度57ns的情況與脈衝寬度40ns的情況,成為同程度的HC閾值。因此,若進行收差修正,即使脈衝寬度為變大(至少60ns為止),HC閾值也不會劣化。 Figure 30 is a graph showing the relationship between the pulse pitch and the HC threshold. This chart is based on the experimental results of Figures 27-29. As shown in FIG. 30, in the case of a pulse width of 57 ns, the HC threshold value is less likely to occur in the case of a pulse width of 40 ns, which is about 2 μJ to 4 μJ. In the case where the number of openings is 0.8, when the number of openings is 0.6, the influence of the difference is small at the condensed point P of the laser light L. Therefore, in the case of a pulse width of 57 ns and a pulse width of 40 ns, Become the same level of HC threshold. Therefore, if the correction is performed, the HC threshold does not deteriorate even if the pulse width is increased (at least 60 ns).

其次,說明關於在SiC基板12的雷射光射入面之表面12a附近的HC品質的加工裕度的實驗結果。圖31~圖33的實驗結果時的實驗條件係如以下所示。首先,以具有4°的斜角之厚度100μm的六方晶系SiC基板12作為 對象,沿著朝與表面12a及a面呈平行的方向延伸之切斷預定線5a,使雷射光L的聚光點P移動。又,以開口數0.8將雷射光L予以聚光。 Next, an experimental result regarding the processing margin of the HC quality in the vicinity of the surface 12a of the laser light incident surface of the SiC substrate 12 will be described. The experimental conditions at the experimental results of Figs. 31 to 33 are as follows. First, a hexagonal SiC substrate 12 having a thickness of 100 μm having an oblique angle of 4° was used as The object moves the light-converging point P of the laser light L along the line to cut 5a extending in a direction parallel to the surfaces 12a and a. Further, the laser light L is condensed by the number of openings of 0.8.

首先,在圖31的實驗結果,以27ns,40ns,50ns,57ns的各自的脈衝寬度照射雷射光L,使用在聚光點位置40.6μm產生半切且在聚光點位置40.6μm未產生半切之能量(脈衝能量),在25.3μm~40.6μm的範圍改變聚光點位置,觀察半切的狀態。雷射光L的脈衝間距作成為14μm之一定狀態。再者,聚光點位置係指從表面12a到聚光點P的位置為止之距離。其結果,幾乎未產生因脈衝寬度所造成之半切的品質的劣化,在脈衝寬度27ns~57ns產生高品質的(半切對切斷預定線的蛇行小)半切。又,加工裕度係脈衝寬度越大則變得越大。當脈衝寬度小時,在一部分的半切容易產生分枝、裂痕(OD)等。 First, in the experimental results of FIG. 31, the laser light L is irradiated with respective pulse widths of 27 ns, 40 ns, 50 ns, and 57 ns, and half-cut is generated at a spot position of 40.6 μm and half-cut at a spot position of 40.6 μm. (Pulse energy), the position of the condensed spot was changed in the range of 25.3 μm to 40.6 μm, and the state of the half cut was observed. The pulse pitch of the laser light L is set to a predetermined state of 14 μm. Furthermore, the position of the condensed spot refers to the distance from the surface 12a to the position of the condensed spot P. As a result, deterioration of the quality of the half-cut due to the pulse width hardly occurs, and a high-quality (small cut to small meandering line) half-cut is generated in the pulse width of 27 ns to 57 ns. Further, the machining margin becomes larger as the pulse width increases. When the pulse width is small, branches, cracks (OD), and the like are easily generated in a part of the half cut.

又,在圖32的實驗結果,以27ns,40ns,50ns,57ns的各自的脈衝寬度照射雷射光L,使脈衝能量在7μJ~12μJ的範圍改變,觀察半切的狀態。雷射光L的脈衝間距係作成為一定的14μm,聚光點位置係作成為一定的34.5μm。其結果,幾乎未產生因脈衝寬度所造成之HC閾值的改變。又,以相同脈衝能量能夠產生相同程度之品質的半切。 Further, in the experimental results of FIG. 32, the laser light L was irradiated with respective pulse widths of 27 ns, 40 ns, 50 ns, and 57 ns, and the pulse energy was changed in the range of 7 μJ to 12 μJ to observe the half-cut state. The pulse pitch of the laser light L is set to be a certain 14 μm, and the position of the light collecting point is set to be a certain 34.5 μm. As a result, almost no change in the HC threshold due to the pulse width occurs. Moreover, half cuts of the same degree of quality can be produced with the same pulse energy.

且,在圖33的實驗結果,以10μm,12μm,14μm,16μm,18μm的各自的脈衝間距照射雷射光L,使脈衝能量在7μJ~12μJ的範圍改變,觀察半切的狀態。雷 射光L的脈衝寬度係作成為一定的57ns,聚光點位置係作成為一定的34.5μm。其結果,幾乎未產生因脈衝寬度所造成之HC閾值的改變。又,在聚光點位置34.5μm的情況,以相同脈衝能量能夠產生相同程度之品質的半切。 Further, in the experimental results of FIG. 33, the laser light L was irradiated at respective pulse intervals of 10 μm, 12 μm, 14 μm, 16 μm, and 18 μm, and the pulse energy was changed in the range of 7 μJ to 12 μJ, and the half-cut state was observed. mine The pulse width of the light beam L is set to be a certain 57 ns, and the position of the light collecting point is set to be a certain 34.5 μm. As a result, almost no change in the HC threshold due to the pulse width occurs. Further, in the case where the condensed spot position is 34.5 μm, half cut of the same degree of quality can be produced with the same pulse energy.

其次,說明關於抑制c面裂痕的其他雷射加工方法。首先,準備具備具有與c面呈斜角分量的角度之表面12a的六方晶系SiC基板12之板狀加工對象物1,並設定切斷預定線5a、5m。接著,如圖34(a)所示,使雷射光L的聚光點P與SiC基板12的內部對位,分別沿著設定於切斷預定線5a(5m)的兩側之2條預備線5p,對加工對象物1照射雷射光L。藉此,沿著各預備線5p,將預備改質區域7p形成於SiC基板12的內部。此預備改質區域7p係包含熔融處理區域。 Next, other laser processing methods for suppressing c-plane cracks will be described. First, a plate-shaped object 1 having a hexagonal SiC substrate 12 having a surface 12a having an angle of an oblique angle to the c-plane is prepared, and the planned cutting lines 5a and 5m are set. Next, as shown in FIG. 34(a), the condensed spot P of the laser light L is aligned with the inside of the SiC substrate 12, and is respectively along two preparatory lines set on both sides of the planned cutting line 5a (5 m). 5p, the object 1 is irradiated with the laser light L. Thereby, the preliminary modified region 7p is formed inside the SiC substrate 12 along each of the preliminary lines 5p. This preliminary modified region 7p includes a molten processed region.

預備線5p係在與表面12a平行的面內,位於切斷預定線5a(5m)的兩側且朝與切斷預定線5a(5m)平行的方向延伸之線。再者,於每個藉由切斷預定線5a、5m所區劃之區域,在SiC基板12的表面12a形成功能元件之情況,預備線5p係從SiC基板12的厚度方向觀看時,設定在相鄰的功能元件之間的區域內為佳。 The standby line 5p is a line extending in a direction parallel to the line to cut 5a (5m) in a plane parallel to the surface 12a, on both sides of the line to cut 5a (5m). Further, in the case where the functional element is formed on the surface 12a of the SiC substrate 12 in each of the regions defined by the cutting planned lines 5a and 5m, the standby line 5p is set in the phase when viewed from the thickness direction of the SiC substrate 12. It is preferred that the area between adjacent functional elements is good.

在沿著各預備線5p,對加工對象物1照射雷射光L之際,比起作為切斷起點的改質區域7a(7m),從預備改質區域7p朝SiC基板12不易產生龜裂。預備改質區域7p係可藉由縮小雷射光L的脈衝能量、脈衝間距、脈衝寬度等,比起作為切斷起點的改質區域7a(7m),能夠 作成為不易在SiC基板12產生龜裂者。 When the laser beam L is irradiated to the object 1 along the respective preparatory lines 5p, cracks are less likely to occur from the preliminary modified region 7p toward the SiC substrate 12 than the modified region 7a (7 m) which is the starting point of the cutting. The preliminary modified region 7p can reduce the pulse energy, the pulse pitch, the pulse width, and the like of the laser light L, and can be compared with the modified region 7a (7 m) which is the starting point of the cutting. It is not easy to cause cracks in the SiC substrate 12.

在沿著預備線5p形成預備改質區域7p後,使雷射光L的聚光點P與SiC基板12的內部對位,再沿著切斷預定線5a(5m)對加工對象物1照射雷射光L。藉此,沿著切斷預定線5a(5m),將作為切斷起點的改質區域7a(7m)形成於SiC基板12的內部。此改質區域7a(7m)係包含熔融處理區域。在沿著切斷預定線5a(5m)形成改質區域7a(7m)後,以改質區域7a(7m)作為起點,沿著切斷預定線5a(5m)切斷加工對象物1。 After the preliminary modified region 7p is formed along the preliminary line 5p, the condensed spot P of the laser light L is aligned with the inside of the SiC substrate 12, and the object 1 is irradiated with lightning along the line to cut 5a (5 m). Light L. Thereby, the modified region 7a (7m) as the cutting start point is formed inside the SiC substrate 12 along the line to cut 5a (5 m). This modified region 7a (7m) contains a molten processed region. After the modified region 7a (7m) is formed along the line to cut 5a (5m), the object 1 is cut along the line to cut 5a (5m) with the modified region 7a (7m) as a starting point.

若依據以上的雷射加工方法,依據以下的理由,可將具備具有與c面呈斜角分量的角度之表面12a的六方晶系SiC基板12之板狀加工對象物1沿著切斷預定線5a、5m精度良好地予以切斷,其結果,能夠獲得沿著切斷預定線5a、5m被精度良好地切斷之加工對象物1(即,功率元件)。 According to the above-described laser processing method, the plate-shaped object 1 having the hexagonal SiC substrate 12 having the surface 12a having an angle of an oblique angle to the c-plane can be along the line to be cut. 5a and 5m are cut off with high precision, and as a result, the object 1 (i.e., power element) that is accurately cut along the line to cut 5a, 5m can be obtained.

即,在沿著切斷預定線5a(5m),在SiC基板12的內部形成改質區域7a(7m)時,沿著各預備線5p,於SiC基板12的內部形成預備改質區域7p。然後,預備線5p係在與表面12a平行的面內,位於切斷預定線5a(5m)的兩側且朝與切斷預定線5a(5m)平行的方向延伸。因此,即使龜裂從改質區域7a(7m)朝c面方向伸展,比起如圖34(b)所示未形成預備改質區域7p之情況,如圖34(a)所示,該龜裂(c面裂痕)的伸展也會被預備改質區域7p所抑制。藉此,不需考量龜裂從改質區域 7a(7m)朝c面方向是否容易伸展,即可使龜裂從改質區域7a(7m)朝SiC基板12的厚度方向變得容易伸展地對加工對象物1照射雷射光。再者,由於預備改質區域7p不需要作為切斷的起點來發揮功能(即,不需要促進龜裂從預備改質區域7p朝SiC基板12的厚度方向伸展),藉由龜裂不易產生於SiC基板12的雷射光L的照射來形成,因此,當形成預備改質區域7p時,容易抑制龜裂從預備改質區域7p朝c面方向伸展。因此,能夠將具備具有與c面呈斜角分量的角度的主面之六方晶系SiC基板12的板狀加工對象物沿著切斷預定線5a(5m)精度良好地予以切斷。 In other words, when the modified region 7a (7m) is formed inside the SiC substrate 12 along the line to cut 5a (5 m), the preliminary modified region 7p is formed inside the SiC substrate 12 along each of the preliminary lines 5p. Then, the preparatory line 5p is located in a plane parallel to the surface 12a, is located on both sides of the line to cut 5a (5m), and extends in a direction parallel to the line to cut 5a (5m). Therefore, even if the crack extends from the modified region 7a (7m) toward the c-plane direction, the turtle is not formed as shown in Fig. 34(b), as shown in Fig. 34(a). The extension of the cleft (c-crack) is also inhibited by the preparatory modified region 7p. Therefore, there is no need to consider cracks from the modified area. When the 7a (7m) is easily stretched in the c-plane direction, the object 1 can be irradiated with laser light from the modified region 7a (7m) so as to be easily extended in the thickness direction of the SiC substrate 12. Further, since the preliminary modified region 7p does not need to function as a starting point of the cutting (that is, it is not necessary to promote the crack from the preliminary modified region 7p toward the thickness direction of the SiC substrate 12), the crack is not easily generated by the crack. Since the laser light L of the SiC substrate 12 is irradiated, it is easy to suppress the crack from extending from the preliminary modified region 7p toward the c-plane direction when the preliminary modified region 7p is formed. Therefore, the plate-shaped object to be processed having the hexagonal SiC substrate 12 having the main surface at an angle of the oblique surface of the c-plane can be accurately cut along the line to cut 5a (5 m).

又,當形成改質區域7a(7m)時,在使雷射光L的聚光點P對位於自SiC基板12的雷射光射入面之表面12a起預定的距離之位置的情況時,預備改質區域7p的形成時,也使雷射光L的聚光點P對位於自表面12a起的相同距離之位置。藉此,能夠更確實地抑制龜裂從改質區域7a(7m)朝c面方向之伸展。 Further, when the modified region 7a (7m) is formed, when the condensed spot P of the laser light L is positioned at a predetermined distance from the surface 12a of the laser light incident surface of the SiC substrate 12, the preparation is changed. At the time of formation of the mass region 7p, the condensed spot P of the laser light L is also positioned at the same distance from the surface 12a. Thereby, it is possible to more reliably suppress the extension of the crack from the modified region 7a (7 m) toward the c-plane direction.

再者,即使沿著各預備線5p,在SiC基板12的內部形成預備改質區域7p的同時,沿著設定在這些預備線5p之間的切斷預定線5a(5m),在SiC基板12的內部形成改質區域7a(7m),c面裂痕的伸展也會被預備改質區域7p所抑制。在此情況,對沿著切斷預定線5a(5m)之改質區域7a(7m)的形成,使沿著預備線5p之預備改質區域7p的形成先進行為佳。 Further, even if the preliminary modified region 7p is formed inside the SiC substrate 12 along each of the preliminary lines 5p, the SiC substrate 12 is formed along the planned cutting line 5a (5 m) set between the preliminary lines 5p. The inside of the modified region 7a (7m) is formed, and the extension of the c-plane crack is also suppressed by the preliminary modified region 7p. In this case, the formation of the modified region 7a (7m) along the line to cut 5a (5m) is excellent in the formation of the preliminary modified region 7p along the preliminary line 5p.

[產業上的利用可能性] [Industry use possibility]

若依據本發明,沿著切斷預定線,能將具備具有與c面呈斜角分量的角度的主面之六方晶系SiC基板之板狀加工對象物精度良好地予以切斷。 According to the present invention, the plate-shaped object to be processed having the hexagonal SiC substrate having the principal surface having an oblique angle component to the c-plane can be accurately cut along the line to be cut.

1‧‧‧加工對象物 1‧‧‧Processing objects

5a、5m‧‧‧切斷預定線 5a, 5m‧‧‧ cut-off line

5p‧‧‧預備線 5p‧‧‧Preparation line

7a、7m‧‧‧改質區域 7a, 7m‧‧‧ modified areas

7p‧‧‧預備改質區域 7p‧‧‧Prepared modified area

12‧‧‧SiC基板 12‧‧‧ SiC substrate

12a‧‧‧表面(主面) 12a‧‧‧Surface (main surface)

12b‧‧‧裏面(主面) 12b‧‧‧ inside (main face)

L‧‧‧雷射光 L‧‧‧Laser light

P‧‧‧聚光點 P‧‧‧ spotlight

圖1係用於形成改質區域之雷射加工裝置的構成圖。 Fig. 1 is a configuration diagram of a laser processing apparatus for forming a modified region.

圖2係進行雷射加工前的加工對象物的平面圖。 Fig. 2 is a plan view of an object to be processed before laser processing.

圖3係沿著圖2的加工對象物的III-III線之斷面圖。 Fig. 3 is a cross-sectional view taken along line III-III of the object of Fig. 2;

圖4係進行雷射加工後的加工對象物的平面圖。 Fig. 4 is a plan view showing an object to be processed after laser processing.

圖5係沿著圖4的加工對象物的V-V線之斷面圖。 Fig. 5 is a cross-sectional view taken along line V-V of the object of Fig. 4;

圖6係沿著圖4的加工對象物的VI-VI線之斷面圖。 Fig. 6 is a cross-sectional view taken along line VI-VI of the object of Fig. 4;

圖7係成為本發明的一實施形態的雷射加工方法的對象之加工對象物的平面圖。 Fig. 7 is a plan view showing an object to be processed which is a target of the laser processing method according to the embodiment of the present invention.

圖8係顯示圖7的加工對象物的結晶構造之圖。 Fig. 8 is a view showing a crystal structure of the object to be processed of Fig. 7;

圖9係圖7的加工對象物的一部分斷面圖。 Fig. 9 is a partial cross-sectional view showing the object to be processed of Fig. 7;

圖10係實施了本發明的一實施形態的雷射加工方法之加工對象物的一部分斷面圖。 Fig. 10 is a partial cross-sectional view showing an object to be processed in a laser processing method according to an embodiment of the present invention.

圖11係實施了本發明的一實施形態的雷射加工方法之加工對象物的一部分斷面圖。 Fig. 11 is a partial cross-sectional view showing an object to be processed in a laser processing method according to an embodiment of the present invention.

圖12係實施了本發明的一實施形態的雷射加工方法之加工對象物的一部分斷面圖。 Fig. 12 is a partial cross-sectional view showing an object to be processed in a laser processing method according to an embodiment of the present invention.

圖13係實施了本發明的一實施形態的雷射加工方法之加工對象物的一部分斷面圖。 Fig. 13 is a partial cross-sectional view showing an object to be processed in a laser processing method according to an embodiment of the present invention.

圖14係顯示藉由本發明的一實施形態的雷射加工方法所切斷的SiC基板的切斷面的照片之圖。 Fig. 14 is a view showing a photograph of a cut surface of a SiC substrate cut by a laser processing method according to an embodiment of the present invention.

圖15係顯示藉由本發明的一實施形態的雷射加工方法所切斷的SiC基板的切斷面的照片之圖。 Fig. 15 is a view showing a photograph of a cut surface of a SiC substrate cut by a laser processing method according to an embodiment of the present invention.

圖16係顯示藉由本發明的一實施形態的雷射加工方法所切斷的SiC基板的平面照片之圖。 Fig. 16 is a plan view showing a plan view of a SiC substrate cut by a laser processing method according to an embodiment of the present invention.

圖17係用來針對在SiC基板的內部所產生的c面裂痕進行說明之斜視圖。 Fig. 17 is a perspective view for explaining a c-plane crack generated inside the SiC substrate.

圖18係顯示產生c面裂痕的SiC基板的切斷面的照片之圖。 Fig. 18 is a view showing a photograph of a cut surface of a SiC substrate in which a c-plane crack is generated.

圖19係顯示脈衝寬度與ID閾值、HC閾值及加工裕度之關係的表。 Fig. 19 is a table showing the relationship between the pulse width and the ID threshold, the HC threshold, and the processing margin.

圖20係顯示脈衝間距與ID閾值、HC閾值及加工裕度之關係的表。 Fig. 20 is a table showing the relationship between the pulse pitch and the ID threshold, the HC threshold, and the processing margin.

圖21係顯示脈衝寬度及脈衝間距的加工裕度的實驗結果之表。 Fig. 21 is a table showing experimental results of processing margins of pulse width and pulse pitch.

圖22係顯示脈衝寬度及脈衝間距的加工裕度的實驗結果之表。 Fig. 22 is a table showing experimental results of processing margins of pulse width and pulse pitch.

圖23係顯示脈衝寬度及脈衝間距的加工裕度的實驗結果之表。 Fig. 23 is a table showing experimental results of processing margins of pulse width and pulse pitch.

圖24係顯示脈衝間距與HC閾值之關係的圖表。 Figure 24 is a graph showing the relationship between the pulse pitch and the HC threshold.

圖25係顯示脈衝間距與ID閾值之關係的圖表。 Figure 25 is a graph showing the relationship between pulse pitch and ID threshold.

圖26係顯示脈衝間距與加工裕度之關係的圖表。 Fig. 26 is a graph showing the relationship between the pulse pitch and the machining margin.

圖27係顯示脈衝寬度及脈衝間距的加工裕度的實驗結果之表。 Fig. 27 is a table showing experimental results of processing margins of pulse width and pulse pitch.

圖28係顯示脈衝寬度及脈衝間距的加工裕度的實驗結果之表。 Fig. 28 is a table showing experimental results of processing margins of pulse width and pulse pitch.

圖29係顯示脈衝寬度及脈衝間距的加工裕度的實驗結果之表。 Fig. 29 is a table showing experimental results of processing margins of pulse width and pulse pitch.

圖30係顯示脈衝間距與HC閾值之關係的圖表。 Figure 30 is a graph showing the relationship between the pulse pitch and the HC threshold.

圖31係顯示在雷射光射入面附近之HC品質的加工裕度的實驗結果之表。 Fig. 31 is a table showing the experimental results of the processing margin of HC quality in the vicinity of the laser light incident surface.

圖32係顯示在雷射光射入面附近之HC品質的加工裕度的實驗結果之表。 Fig. 32 is a table showing experimental results of processing margin of HC quality in the vicinity of the laser light incident surface.

圖33係顯示在雷射光射入面附近之HC品質的加工裕度的實驗結果之表。 Fig. 33 is a table showing the experimental results of the processing margin of HC quality in the vicinity of the laser light incident surface.

圖34係用來說明本發明的其他實施形態的雷射加工方法之平面圖。 Figure 34 is a plan view for explaining a laser processing method according to another embodiment of the present invention.

1‧‧‧加工對象物 1‧‧‧Processing objects

5a、5m‧‧‧切斷預定線 5a, 5m‧‧‧ cut-off line

7a、7m‧‧‧改質區域 7a, 7m‧‧‧ modified areas

12‧‧‧SiC基板 12‧‧‧ SiC substrate

12a‧‧‧表面(主面) 12a‧‧‧Surface (main surface)

12b‧‧‧裏面(主面) 12b‧‧‧ inside (main face)

23‧‧‧擴展帶 23‧‧‧Expansion belt

L‧‧‧雷射光 L‧‧‧Laser light

P‧‧‧聚光點 P‧‧‧ spotlight

Claims (2)

一種雷射加工方法,係用來將具備具有與c面呈斜角分量的角度之主面的六方晶系SiC基板之板狀加工對象物,分別沿著朝與前述主面及a面平行的方向延伸之第1切斷預定線以及朝與前述主面及m面平行的方向延伸之第2切斷預定線予以切斷之雷射加工方法,其特徵為具備有:第1製程,其係藉由使雷射光的聚光點對位於前述SiC基板的內部,沿著前述第1切斷預定線,對前述加工對象物照射前述雷射光,來沿著前述第1切斷預定線,將作為切斷起點的第1改質區域形成於前述SiC基板的內部;和第2製程,其係在前述第1製程後,藉由使前述聚光點對位於前述SiC基板的內部,沿著前述第2切斷預定線,對前述加工對象物照射前述雷射光,來沿著前述第2切斷預定線,將作為切斷起點的第2改質區域形成於前述SiC基板的內部;在進行前述第2製程後,以前述第1改質區域作為起點,沿著前述第1切斷預定線切斷前述加工對象物,以前述第2改質區域作為起點,沿著前述第2切斷預定線切斷前述加工對象物之第3製程。 A laser processing method for forming a plate-shaped object to be processed having a hexagonal SiC substrate having a principal surface having an oblique angle component to a c-plane, respectively, along a direction parallel to the main surface and the a-plane A laser processing method in which a first cutting planned line extending in a direction and a second cutting planned line extending in a direction parallel to the main surface and the m-plane are cut is characterized in that: a first process is provided By concentrating the condensing point of the laser light in the inside of the SiC substrate, the laser beam is irradiated onto the object to be processed along the first line to cut, and the first line is cut along the first line to be cut. a first modified region in which the starting point is cut is formed inside the SiC substrate; and a second process is performed after the first process, and the condensed spot is located inside the SiC substrate, along the first (2) cutting the predetermined line, irradiating the target object with the laser beam, and forming a second modified region as a cutting start point in the inside of the SiC substrate along the second cutting planned line; After the 2 process, the first modified area is used as the The starting point is that the object to be processed is cut along the first line to be cut, and the third process of cutting the object to be processed along the second line to cut is started with the second modified region as a starting point. 如申請專利範圍第1項之雷射加工方法,其中,前述第1改質區域及前述第2改質區域係包含熔融處理區域。 The laser processing method according to claim 1, wherein the first modified region and the second modified region comprise a molten processed region.
TW101100603A 2011-01-13 2012-01-06 Laser processing method TWI546852B (en)

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