TWI703003B - Sapphire wafer processing method and laser processing device - Google Patents

Abstract

The subject of the present invention is to form a modified layer well regardless of the difference in crystal defects of the sapphire wafer. The solution is a sapphire wafer processing method, and it is made into the following structure: It has a predetermined laser processing condition to irradiate the remaining area of the outer periphery with laser light relative to the sapphire wafer on the work clamp table to test the processing modification The step of layering, calculate the reforming layer formation rate from the captured image of the reforming layer in the remaining area of the outer periphery of the sapphire wafer, and select from the relational data the reformation of the laser processing under the predetermined processing conditions The step of establishing the optimal laser processing conditions related to the layer formation rate, and the step of irradiating the laser light along the predetermined dividing line of the sapphire wafer under the optimal laser processing conditions, and forming a modified layer along the predetermined dividing line.

Description

Sapphire wafer processing method and laser processing device Invention field

The invention relates to a method and a laser processing device for processing a sapphire wafer by dividing a sapphire wafer into individual device wafers.

Background of the invention

The sapphire wafer is formed by arranging optical devices such as light-emitting elements on the front surface of the sapphire substrate. As a method of dividing such sapphire wafers, there is known a method of irradiating laser light along the scribe line to form a modified layer inside, and then dividing the sapphire wafer with the modified layer as a starting point (see, for example, Patent Document 1 ). The modified layer is formed by multiphoton absorption generated by the condensing of laser light, and the forming part of the modified layer becomes weaker than other areas in the substrate. By applying an external force near the modified layer whose strength has been reduced, the sapphire wafer can be divided into individual device wafers along the dicing path.

Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2013-105847

However, the purity mark of the sapphire wafer does not necessarily correspond to the proportion of crystal defects (the proportion of oxygen defects). When the supply source of the sapphire wafer is different, even if the purity mark of the sapphire wafer is the same, the ratio of crystal defects is different, and it is difficult to form a modified layer at the oxygen defect portion of the sapphire wafer. Therefore, when sapphire wafers from different supply sources are mixed, even if laser processing is performed on the sapphire wafer under the same processing conditions, there will still be differences in the formation of the modified layer, and it will not be able to be divided well. Sapphire wafer.

The present invention is an invention made in view of the above points, and its object is to provide a sapphire wafer processing method and a laser processing apparatus capable of forming a modified layer well regardless of the difference in the crystal defects of the sapphire wafer.

The processing method of the sapphire wafer of the present invention is to process a sapphire wafer having a device area on the front side and a peripheral remaining area surrounding the device area, and the device area is formed with a plurality of devices and a plurality of predetermined dividing lines. The sapphire wafer processing method includes: a relational data preparation step, which prepares the relational data that has associated the modified layer formation rate and the optimal laser processing conditions according to each type of sapphire wafer, and the modified layer formation rate is The laser light of the wavelength penetrating the sapphire wafer is positioned inside a plurality of sapphire wafers of different types, and irradiated under predetermined laser processing conditions to form a modified layer inside the sapphire wafer, and The formation state of the modified layer photographed is processed by image processing The sapphire wafer held on the upper surface of the work clamp table of the laser processing device will be penetrating to the sapphire wafer after the step of forming a modified layer in the remaining area of the outer periphery. The laser light of the wavelength of λ is positioned inside and irradiates the remaining area of the outer periphery under the predetermined laser processing conditions to form a modified layer inside the sapphire wafer; the step of selecting the best laser processing conditions is to implement the modification of the remaining area of the outer periphery After the quality layer formation step, the formed modified layer is photographed by the imaging device and the formation rate of the modified layer is calculated by image processing, and the type of the sapphire wafer and the best laser processing conditions are selected according to the relationship data; The irradiating step of irradiating the laser light along the predetermined dividing line of the sapphire wafer under the selected optimal laser processing conditions to form a modified layer along the predetermined dividing line; and the dividing step, implementing the After the laser light irradiation step, an external force is applied to the sapphire wafer to divide the sapphire wafer along the planned dividing line with the modified layer as a starting point.

The laser processing device of the present invention is provided with a work clamp table, laser light irradiation equipment, imaging equipment and control equipment. The work clamp table is held on a sapphire wafer with a device area on the front side and a peripheral remaining area surrounding the device area , And the device area is formed with a plurality of devices and a plurality of predetermined dividing lines. The laser light irradiation equipment irradiates the sapphire crystal with a laser light of a wavelength that is penetrating to the sapphire wafer held on the work clamp Inside the circle, the camera equipment is used to photograph the front side of the sapphire wafer held on the work chuck. The laser processing device is characterized by having storage Equipment, the storage device is to store the modified layer formation rate and the best laser processing conditions have been associated with each type of sapphire wafer, the modified layer formation rate is for multiple sapphires of different types The wafer locates the laser light inside the sapphire wafer under predetermined laser processing conditions and irradiates it to form a modified layer, and photographs the modified layer and uses image recognition to evaluate the formation state of the modified layer When the sapphire wafer is held on the work clamp table, the laser light irradiation equipment will position the laser light with a wavelength penetrating the sapphire wafer inside the sapphire wafer, and The predetermined laser processing conditions irradiate the remaining area of the outer periphery to form a modified layer inside the sapphire wafer. The imaging device will capture the formed modified layer forming area, and the control device will obtain information from the captured image Calculate the formation rate of the modified layer and select the optimal laser processing conditions based on the relational data. The laser light irradiation equipment will use the selected optimal laser processing conditions along the predetermined division of the sapphire wafer The line irradiates the laser light.

According to these structures, the formation rate of the modified layer and the optimal laser processing conditions can be correlated for each type of sapphire wafer by predetermined laser processing conditions, and stored in advance as relationship data. The modified layer is tested and processed on the remaining area of the outer periphery of the sapphire wafer under predetermined laser processing conditions, and the formation rate of the modified layer under the predetermined laser processing conditions for the sapphire wafer is calculated. Refer to the relational data and select the type of sapphire wafer and the optimal laser processing conditions from the formation rate of the modified layer, and use the optimal laser processing conditions to perform laser processing along the planned dividing line of the sapphire wafer. Since the selected is due to the difference in crystal defects of the sapphire wafer The best laser processing conditions are different, so regardless of the difference in the crystal defects of the sapphire wafer, the modified layer can be formed and divided into individual device wafers.

According to the present invention, the formation rate of the modified layer and the optimal laser processing conditions can be correlated and stored for each type of sapphire wafer. Therefore, by testing and processing the modified layer on the sapphire wafer, the type of sapphire wafer and the optimal laser processing conditions can be selected, and the modified layer can be formed well regardless of the difference in crystal defects of the sapphire wafer.

1: Laser processing device

10: Abutment

11: Standing wall

12: Arm

20: Work clamp

21: Keep the face

22: Fixture Department

30: Work clamp table moving mechanism

31, 32: rail

33: X-axis table

34: Y-axis table

35, 36: Ball screw

37, 38: drive motor

40: Laser light irradiation equipment

41: Processing head

42: camera equipment

45: control equipment

46: storage equipment

51: Expansion drum

52: Frame holding part

55: modified layer

A1: Device area

A2: Remaining area of outer periphery

F: Frame

L: Split planned line

M: pulse mark

T: Keep the tape

W, WA, WB, WC, WD: sapphire wafer

X, Y, Z: direction

Fig. 1 is a perspective view of the laser processing apparatus of this embodiment.

Fig. 2 is an explanatory diagram of a method of selecting laser processing conditions in this embodiment.

Fig. 3 is a diagram showing an example of a relationship data preparation procedure of the present embodiment.

Fig. 4 is a diagram showing an example of a step of forming a reforming layer in the outer periphery remaining area of the present embodiment.

Fig. 5 is a diagram showing an example of the step of selecting the optimum laser processing conditions in this embodiment.

Fig. 6 is a diagram showing an example of the laser beam irradiation procedure of the present embodiment.

Fig. 7 is a diagram showing an example of the division procedure in this embodiment.

The form used to implement the invention

Hereinafter, the laser processing apparatus of this embodiment will be described with reference to the attached drawings. Fig. 1 is a perspective view of the laser processing apparatus of this embodiment. In addition, the laser processing apparatus shown below is a processing apparatus which shows one example, and is not limited to this structure. The laser processing apparatus may be appropriately modified as long as it is a processing method applicable to the sapphire wafer of this embodiment.

As shown in FIG. 1, the laser processing apparatus 1 is configured to relatively move a laser beam irradiating device 40 that irradiates a laser beam and a work chuck 20 holding a sapphire wafer W to process the sapphire wafer W by laser. . On the front surface of the sapphire wafer W, a plurality of planned dividing lines L are arranged in a grid pattern, and LEDs (Light Emitting Diodes), etc. are formed in each area divided by the planned dividing lines L Multiple devices (not shown). In addition, the front surface of the sapphire wafer W is divided into a device area A1 in which a plurality of devices are formed, and a peripheral remaining area A2 surrounding the device area A1.

In addition, the central part of the holding tape T is attached to the sapphire wafer W, and the ring-shaped frame F is attached to the outer peripheral part of the holding tape T. The sapphire wafer W is carried into the laser processing apparatus 1 while being supported on the frame F through the holding tape T.

The base 10 of the laser processing apparatus 1 is provided with a work chuck table moving mechanism 30 that moves the work chuck table 20 in the X-axis direction and the Y-axis direction. The work clamp table moving mechanism 30 has a pair of guide rails 31 parallel to the X-axis direction arranged on the base 10 and a motor-driven X-axis table 33 slidably disposed on the pair of guide rails 31. In addition, the work clamp table moving mechanism 30 is equipped with A pair of guide rails 32 parallel to the Y-axis direction placed on the upper surface of the X-axis table 33, and a motor-driven Y-axis table 34 slidably disposed on the pair of guide rails 32.

The back sides of the X-axis table 33 and the Y-axis table 34 are respectively formed with nut parts not shown in the figure, and ball screws 35 and 36 are screwed into these nut parts. In addition, the work chuck table 20 can be moved along the guide rails 31 and 32 in the X-axis direction and the Y-axis direction by rotating and driving the drive motors 37 and 38 connected to one end of the ball screws 35 and 36. In addition, the Y-axis table 34 is provided with a work clamp table 20 capable of holding the sapphire wafer W. A holding surface 21 is formed on the upper surface of the work chuck table 20, and around the work chuck table 20, a clamp part 22 that can hold and fix the frame F around the sapphire wafer W is provided.

An arm portion 12 is protrudingly provided on the upright wall portion 11 at the rear of the work chuck table 20, and a laser light irradiation device 40 is installed at the front end of the arm portion 12 so as to face the work chuck table 20 in the vertical direction. The processing head 41 of the laser light irradiation equipment 40 irradiates the laser light (pulse laser) generated by the oscillator (not shown) oscillating toward the sapphire wafer W held on the work chuck 20. The laser light has a wavelength that is penetrative to the sapphire wafer W, and the laser light is condensed inside the sapphire wafer W to form pulse marks.

By continuously forming the pulse marks along the planned dividing line L, the modified layer 55 (refer to FIG. 3) as the starting point of dividing can be formed in the sapphire wafer W. Furthermore, the so-called impulse mark refers to the condition of cracks elongated from the laser spot. In addition, the so-called modified layer 55 means the density, refractive index, mechanical strength, and other things inside the sapphire wafer W due to the irradiation of laser light. The physical properties are different from the surroundings, and the intensity is lower than the surrounding areas. The modified layer 55 may be, for example, a melt-processed area, a cracked area, a dielectric breakdown area, or a refractive index change area, or a mixed area of these areas.

An imaging device 42 capable of photographing the front side of the sapphire wafer W is provided on the side of the laser light irradiation device 40. The processing head 41 and the sapphire wafer W can be calibrated based on the image taken by the imaging device 42. In addition, the laser processing device 1 is provided with a control device 45 that integrates each part of the control device, and a storage device 46 that stores relational data described later. The control device 45 and the storage device 46 are composed of a processor and a memory that perform various processing. The memory is composed of one or more storage media such as ROM (Read Only Memory) and RAM (Random Access Memory) due to application.

However, although the purity is marked on the sapphire wafer W, even with the same purity mark, the crystal defects of the sapphire wafer W (that is, it is difficult to form pulse marks) in each supplier (each type) The proportion of hypoxic parts) will still be different. Therefore, even if laser processing is performed on the sapphire wafer W with the same purity mark under the same laser processing conditions, the formation status of the modified layer 55 (refer to FIG. 3) inside the sapphire wafer W is not necessarily identical. Although appropriate laser processing conditions must be selected for the sapphire wafer W, it is not possible to select the best laser processing conditions based on the purity mark of the sapphire wafer W.

Therefore, in the laser processing apparatus 1 of the present embodiment, as a reference material for selecting the laser processing conditions, it is necessary to prepare in advance. The relationship data is to associate the formation rate of the modified layer and the optimal laser processing conditions for each type of sapphire wafer W. Then, test and process the modified layer 55 on the sapphire wafer W (see FIG. 3), and refer to the relational data from the modified layer formation rate during the test process to select the type and type of the sapphire wafer W in actual production. The best laser processing conditions. According to this, even if the types of sapphire wafers are random and the ratios of crystal defects are different, the modified layer 55 can still be formed satisfactorily under the optimal laser processing conditions.

Here, the method of selecting laser processing conditions is explained in detail. Fig. 2 is an explanatory diagram of a method of selecting laser processing conditions in this embodiment. Fig. 2 is an example of a photographed image showing a region where the modified layer is formed, and Table 1 is an example of showing relational data.

As shown in FIG. 2, in the captured image of the modified layer formation region of the sapphire wafer W, a plurality of pulse traces M arranged in a row are displayed. A plurality of pulse marks M are photographed by aligning the focus of the imaging device 42 (refer to FIG. 1) on the modified layer 55 formed along the planned dividing line L (refer to FIG. 1) under predetermined laser processing conditions . Each pulse mark M in the sapphire wafer W is displayed darkly due to light scattering. Therefore, by performing image processing such as binarization processing on the captured image, the pulse mark M can be displayed as black pixels. From the display status of the black pixels in the captured image, etc., the reforming layer formation rate (pulse mark generation rate) relative to the sapphire wafer W can be calculated.

In addition, since the pulse mark M is not formed on the oxygen-deficient part of the sapphire wafer W, the modified layer will be changed according to the ratio of crystal defects. The formation rate changes. For example, in a sapphire wafer WA having almost no crystal defects, pulse marks M are formed on all the irradiated parts of the laser light, and the reforming layer formation rate becomes 100%. In addition, in the sapphire wafer WB with a small proportion of crystal defects, the pulse mark M is formed in a part of the laser beam irradiation part, so that the reforming layer formation rate becomes 80%. In addition, in the sapphire wafer WC with a large proportion of crystal defects, the pulse mark M is formed in most of the irradiated parts of the laser light, so that the reforming layer formation rate becomes 40%.

In this way, the ratio of crystal defects is different for each type of sapphire wafer W, and there is a difference in the formation rate of the modified layer corresponding to the ratio of crystal defects, and for each type of sapphire wafer W The best laser processing conditions are different. Therefore, the storage device 46 (refer to FIG. 1) of the laser processing apparatus 1 can store the relationship data which can select the type of the sapphire wafer W and the optimal laser processing conditions from the formation rate of the modified layer.

As shown in Table 1, the relational data is the formation rate of the modified layer when processed under the predetermined laser processing conditions, and the laser processing conditions that are optimal for the formation rate of the modified layer, according to each sapphire wafer The type of W is related to data. For example, the modified layer formation rate can be 95% or more, the modified layer formation rate is 80% or more and less than 95%, the modified layer formation rate is 40% or more and less than 80%, and the modified layer formation rate is less than 40%. %, the type WA-WD of each sapphire wafer W is associated with the optimal laser processing condition AD. Furthermore, the so-called type of sapphire wafer W includes not only differences in the manufacturer of the supply source, but also differences in the thickness, actual purity, and manufacturing method of the sapphire wafer.

In addition, the so-called optimal laser processing conditions refer to laser processing conditions where a plurality of types of sapphire wafers W are actually laser processed so that the formation rate of the modified layer becomes 100%. The laser processing conditions are, for example, using the laser processing condition A as a reference, and as the reforming layer formation rate becomes smaller, the laser output is set to increase and the processing feed rate is slowed down. By referring to the relational data, it becomes possible to select the best for any sapphire wafer W from the reforming layer formation rate obtained by testing and processing the reforming layer 55 under predetermined processing conditions for any sapphire wafer W Laser processing conditions.

3 to 7, the processing method of the sapphire wafer of this embodiment will be described. Each is shown. Figure 3 is an example of the relationship data preparation step, Figure 4 is an example of the modification layer formation step of the remaining peripheral area, Figure 5 is an example of the selection step of the optimal laser processing conditions, and Figure 6 is the laser light irradiation An example of the steps, Fig. 7 is an example of the division step.

As shown in Fig. 3, the relationship data preparation step is performed before the processing of the sapphire wafer. In the relational data preparation step, a plurality of sapphire wafers W of different types are prepared, and the laser light is positioned and irradiated inside each sapphire wafer W, and the laser beam is placed on the sapphire wafer W under predetermined laser processing conditions. A modified layer 55 is formed inside. Then, the imaging device 42 photographs the reforming layer formation area of each sapphire wafer W, and the control device 45 determines the formation state of the reforming layer 55 in the captured image and digitizes it by image processing. Quality layer formation rate. The reforming layer formation rate and the type of each sapphire wafer W are correlated and stored in the storage device 46.

In addition, although the details are not shown, the laser processing can be repeated while changing the laser processing conditions to determine the The best laser processing conditions for the type of stone wafer W. The optimal laser processing conditions and the formation rate of the modified layer are associated with the type of each sapphire wafer W and stored in the storage device 46. In this manner, the relationship data (refer to Table 1) in which the formation rate of the modified layer and the laser processing conditions have been correlated for each type of sapphire wafer W can be stored in the storage device 46. In addition, the reforming layer formation rate can be calculated by image processing of the captured image, and is not limited to the method of binary processing. For example, it can be calculated from the captured image and the reforming layer formation rate 100 % Is calculated from the correlation value calculated by the matching process of the reference image.

As shown in FIG. 4, after the relational data preparation step, the outer peripheral remaining area reforming layer forming step may be implemented. In the step of forming the reforming layer of the outer peripheral remaining area, the sapphire wafer W is held on the upper surface of the work chuck 20 (see FIG. 5) of the laser processing apparatus 1 (see FIG. 1), and the sapphire wafer W is The surrounding frame F is held on the clamp part 22. In addition, the irradiation port of the processing head 41 is positioned on the outer peripheral remaining area A2 of the sapphire wafer W, and the laser light is irradiated on the outer peripheral remaining area A2 under predetermined laser processing conditions. Then, by moving the processing head 41 relative to the sapphire wafer W, the modified layer 55 can be tested and processed inside the sapphire wafer W.

As shown in FIG. 5, after the step of forming the modified layer in the remaining area of the outer periphery, the step of selecting the optimal laser processing conditions can be implemented. In the step of selecting the optimal laser processing conditions, the imaging device 42 is positioned directly above the remaining peripheral area A2 of the sapphire wafer W after the test processing, and the focus of the imaging device 42 is lowered to the inside of the sapphire wafer W Shoot the area where the modified layer is formed. The captured image of the remaining peripheral area A2 can be performed by the control device 45 Image processing is performed to calculate the formation rate of the modified layer of the sapphire wafer W. Then, by the control device 45 and based on the above-mentioned relational data (refer to Table 1), the type of sapphire wafer W that has been correlated with the formation rate of the modified layer and the optimal laser processing conditions can be selected.

As shown in FIG. 6, the laser light irradiation step can be implemented after the step of selecting the optimal laser processing conditions. In the laser beam irradiation step, the irradiation port of the processing head 41 is positioned on the planned dividing line L (see FIG. 4) of the sapphire wafer W, and the laser is irradiated along the planned dividing line L under the optimal laser processing conditions. Shoot the light. Then, by relatively moving the processing head 41 with respect to the sapphire wafer W, the modified layer 55 can be formed along the planned dividing line L. By repeatedly performing this processing and feeding, the modified layer 55 can be formed along all the planned dividing lines L of the sapphire wafer W. In this way, the modified layer 55 can be formed on the sapphire wafer W under the optimum laser processing conditions corresponding to the type of the sapphire wafer W.

As shown in Fig. 7, the segmentation step may be implemented after the laser light irradiation step. In the dividing step, the wafer W is placed on the expansion roller 51 of the expansion device (not shown), and the frame F around the sapphire wafer W is held in the frame holding portion 52. At this time, the expansion roller 51 has a larger diameter than the sapphire wafer W, and the outer peripheral edge of the expansion roller 51 contacts the holding tape T between the sapphire wafer W and the frame F from the lower side. Then, by moving the frame holding portion 52 in the descending direction, the expansion drum 51 can be relatively pushed up.

By separating the expansion roller 51 from the frame holding portion 52, the holding tape T will be expanded in the radial direction and pass through the holding tape T An external force is applied to the reforming layer 55 of the sapphire wafer W. In this way, the modified layer 55 whose strength has been reduced is used as a starting point for division, and the sapphire wafer W is divided into individual device wafers C. In this way, even when sapphire wafers W with different crystal defect ratios are mixed, it is still possible to form the modified layer 55 for each sapphire wafer W under the best laser processing conditions, and to divide it well. Into a device wafer C.

As described above, in the sapphire wafer processing method of this embodiment, the reforming layer formation rate under predetermined laser processing conditions and the optimal laser processing conditions are established for each type of sapphire wafer W The association is stored in advance as relational data. The modified layer 55 is tested and processed on the remaining peripheral area A2 of the sapphire wafer W under predetermined laser processing conditions, and the formation rate of the modified layer under the predetermined laser processing conditions for this sapphire wafer W is calculated. Refer to the relational data and select the type of sapphire wafer W and the optimal laser processing conditions from the formation rate of the modified layer, and perform laser along the planned dividing line L of the sapphire wafer W with the optimal laser processing conditions Processing. Since the optimum laser processing conditions are selected in response to the difference in crystal defects of the sapphire wafer W, regardless of the difference in crystal defects of the sapphire wafer W, the modified layer 55 can be well formed and divided into one A device wafer.

In addition, the present invention is not limited to the embodiment described above, and can be implemented with various changes. In the above-mentioned embodiment, the size, shape, etc. illustrated in the drawings are not limited to these, and can be appropriately changed within the range in which the effects of the present invention can be exhibited. In addition, as long as it does not deviate from the scope of the object of the present invention, it can be implemented with appropriate changes.

For example, in the above-mentioned embodiment, although the sapphire wafer W is divided by the expansion of the holding tape in the dividing step, it is not limited to this configuration. In the dividing step, the sapphire wafer W may be divided along the planned dividing line L by applying an external force to the modified layer 55 as a starting point. For example, the sapphire wafer W can be divided by breaking, or by SDBG (Stealth Dicing Before Grinding) that applies a grinding load to the sapphire wafer W after the reforming layer is formed. Split the sapphire wafer W.

In addition, in the above-mentioned embodiment, although the laser processing apparatus 1 is configured to automatically perform the optimal laser processing condition selection step, it is not limited to this structure. The step of selecting the best laser processing conditions can also be the operator referring to the relationship data and enabling the operator to select the best laser processing conditions.

In addition, in the above-mentioned embodiment, although the relationship data is a structure in which the reforming layer formation rate, the optimal laser processing conditions, and the type of the sapphire wafer W are correlated, it is not limited to this structure. The relationship data, as long as at least the formation rate of the modified layer is associated with the optimal laser processing conditions, and other parameters can also be associated.

In addition, in the above-mentioned embodiment, although the processing method of the sapphire wafer W is applied to the sapphire wafer W having substantially the same purity mark, it is not limited to this structure. The processing method of the sapphire wafer W can be applied to sapphire wafers with significantly different purity marks.

Moreover, in the above embodiment, although the best laser The processing conditions are described as laser processing conditions such that the formation rate of the modified layer becomes 100%, but it is not limited to this configuration. The optimal laser processing condition may be a laser processing condition that can separate the sapphire wafer with a reformed layer formation rate, for example, the reformed layer formation rate is 90% or more.

Industrial availability

As explained above, the present invention has the effect that the modified layer can be formed well regardless of the difference in the crystal defects of the sapphire wafer, especially when laser processing is performed on sapphire wafers from different manufacturers. It is useful for processing methods and laser processing equipment for sapphire wafers.

M: pulse mark

55: modified layer

WA, WB, WC, WD: sapphire wafer

Claims (2)

A method for processing a sapphire wafer is to process a sapphire wafer having a device area on the front side and a remaining area surrounding the device area, and the device area is formed with a plurality of devices and a plurality of predetermined dividing lines. The sapphire crystal The circle processing method includes: a relational data preparation step, which prepares relational data that has associated the pulse mark generation rate and the optimal laser processing conditions according to each type of the aforementioned sapphire wafer, and the pulse mark generation rate will be compared to the aforementioned sapphire wafer The laser light of the wavelength that the wafer has a penetrating wavelength is positioned inside a plurality of the aforementioned sapphire wafers of different types, and is irradiated under a predetermined laser processing condition to form a modified layer inside the aforementioned sapphire wafer, and The photographed formation state of the modified layer is digitized by image processing; the step of forming the modified layer in the remaining area of the outer periphery, after the step of preparing the relational data, is held on the work clamp of the laser processing device On the sapphire wafer on the surface, a laser light of a wavelength penetrating the sapphire wafer is positioned inside and irradiated on the remaining area of the outer periphery under the predetermined laser processing conditions to form inside the sapphire wafer The aforementioned modified layer; the step of selecting the optimal laser processing conditions, after performing the step of forming the modified layer in the remaining peripheral area, the formed modified layer is photographed by an imaging device and the pulse mark generation rate is calculated by image processing, And according to the relational data, the type of the sapphire wafer and the aforementioned optimal laser processing conditions are selected; the laser light irradiation step is to irradiate the selected optimal laser processing conditions along the predetermined dividing line of the sapphire wafer Laser light to form the aforementioned modified layer along the predetermined dividing line; and In the dividing step, after the laser light irradiation step is performed, an external force is applied to the sapphire wafer to divide the sapphire wafer along the planned dividing line with the modified layer as a starting point. In the outer peripheral remaining area modified layer forming step, In a state where the focal point of the imaging device that has been positioned directly above the remaining area of the outer periphery is positioned in the modified layer formation area, the imaging device is used to photograph the previously formed modified layer to form a display line A plurality of photographed images of pulse marks are arranged, and the pulse mark generation rate is calculated from the formed photographed images. A laser processing device includes: a work clamp table for holding a sapphire wafer with a device area on the front surface and a peripheral remaining area surrounding the device area, and the device area is formed with a plurality of devices and a plurality of predetermined dividing lines; laser The light irradiation equipment irradiates the laser light of the wavelength penetrating the sapphire wafer held on the work chuck to the inside of the sapphire wafer; the imaging equipment photographs the sapphire held on the work chuck The front side of the wafer; and a control device, the laser processing device is characterized by a storage device, the storage device is to store the pulse mark generation rate and the best laser processing conditions have been associated with each type of the aforementioned sapphire wafer The pulse mark generation rate is based on a plurality of the aforementioned sapphire wafers of different types. The laser beam is positioned inside the aforementioned sapphire wafer under predetermined laser processing conditions and irradiated In order to form a modified layer, the modified layer is photographed and the formation state of the modified layer is digitized by image recognition. When the sapphire wafer is held on the work chuck, the laser The light irradiation equipment will position the laser light of the wavelength penetrating the sapphire wafer inside the sapphire wafer, and irradiate the remaining area of the outer periphery under the predetermined laser processing conditions, so as to irradiate the sapphire crystal The above-mentioned modified layer is formed inside the circle, the imaging device will be positioned directly above the remaining area of the outer periphery and in the state where the focus has been positioned on the modified layer forming region, the formed region of the modified layer will be photographed to form a display There are a plurality of photographed images of pulse marks arranged in a row. The control device calculates the pulse mark generation rate from the photographed image information, and selects the optimum laser processing conditions according to the relational data. The laser light irradiation equipment irradiates the laser light along the predetermined dividing line of the sapphire wafer according to the selected optimal laser processing condition.

Images