TW202030813A - Confirmation method - Google Patents

Abstract

[Question] It is easy to confirm the frontal influence of the laser beam irradiation on the workpiece. [Solution] Form two linear processing traces on the metal foil of the confirmation wafer, and form a modified layer by irradiating a laser beam to the intermediate reference position. Although the modified layer formed inside the base material is difficult to visually recognize, since the linear processing traces are clearly formed on the front surface of the metal foil, they can be easily visually recognized. Therefore, the position of the modified layer (that is, the irradiation position of the laser beam when the modified layer is formed) can be grasped based on the linear processing trace. Therefore, because the user can obtain the positional relationship between the irradiation position of the laser beam and the surface damage caused by the laser beam that reaches the front surface of the substrate, it is easy to confirm the interference caused by the laser beam irradiation. The positive influence of the processed product.

Description

Confirmation method

The present invention relates to a confirmation method for confirming the influence on the front side of the workpiece caused by the irradiation of the laser beam on the back side of the workpiece.

The to-be-processed object used for wafer formation, for example, has an element in each area divided by a plurality of intersecting dicing lines (planned dividing lines) formed on the front surface. The wafer can be formed by cutting the workpiece along the dicing path. Therefore, there is a method of irradiating a laser beam along the scribe line from the back of the workpiece, and forming a modified layer along the scribe line inside the workpiece.

In this method, there are cases where the front side components are affected by the laser beam from the back side. Therefore, what is required is to confirm the presence or extent of this effect. For example, Patent Document 1 discloses a confirmation wafer for confirming the influence of such a laser beam. By irradiating a laser beam from the back of the confirmation wafer to form a modified layer, it is possible to detect damage (hereinafter referred to as surface damage) generated on the front surface of the confirmation wafer. By this, it is possible to confirm the influence of the laser beam on the front of the workpiece, select appropriate processing conditions, and detect abnormalities in the processing device. Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2017-37912

Problems to be solved by the invention

During the formation of the modified layer, surface damage occurs directly behind the irradiated position of the laser beam, that is, in the dicing lane, because there are no elements formed in the dicing lane, so it is not a problem. Therefore, it is important to know how far away from the irradiation position of the laser beam the surface damage occurs.

However, since the dicing line is not formed on the confirmation wafer of Patent Document 1, it is difficult to determine the irradiation position of the laser beam from its appearance. In addition, it is also conceivable to determine the irradiation position of the laser beam from the modified layer. However, because the modified layer is formed inside the confirmation wafer, it is difficult to distinguish from the appearance. In this way, the confirmation wafer of Patent Document 1 has the following problem: it is difficult to grasp the correct irradiation position of the laser beam.

Accordingly, the object of the present invention is to provide a method that can determine the irradiation position of the laser beam when the laser beam for forming a modified layer is irradiated from the back of a confirmation wafer without a dicing path, and easily confirm The method of confirming the positive influence of the laser beam irradiation on the workpiece. Means to solve the problem

According to the present invention, it is possible to provide a confirmation method that confirms that a laser beam with a wavelength that is penetrating to the workpiece is irradiated from the back side of the workpiece by a laser processing device, and a change is formed inside the workpiece. The positive effect of the laser beam irradiation on the workpiece at the time of the quality layer, the aforementioned confirmation method has the following steps: The confirmation wafer preparation step is to prepare the confirmation wafer with metal foil on the front surface of the substrate; The reforming layer forming step includes irradiating a laser with a wavelength penetrating the substrate from the back side of the substrate in a state where the condensing point has been positioned inside the substrate of the confirmation wafer Light beam, and relatively move the condensing point and the confirmation wafer in the processing and feeding direction to form a modified layer inside the substrate; In the step of forming linear processing traces, in the indexing feed direction orthogonal to the processing feed direction, at a predetermined distance from the irradiation position of the laser beam in the reforming layer forming step to condense the light The spot is positioned in the state of the interface between the substrate and the metal foil of the confirmation wafer, and a laser beam with a wavelength penetrating the substrate is irradiated from the back side of the substrate, and the condensing spot Move relative to the confirmation wafer in the processing feed direction, and form linear processing traces on the front surface of the metal foil; and In the confirming step, after performing the modified layer forming step and the linear processing trace forming step, based on the position of the linear processing trace, confirm that the laser beam irradiated in the modified layer forming step The positive effect of the metal foil.

Preferably, the step of forming the modified layer is performed after the step of forming the linear processing trace is performed.

Preferably, the verification method further includes a reference position setting step, and the reference position setting step is to set the position on the verification wafer where the modified layer is to be formed after the verification wafer preparation step is performed As a reference position. Preferably, in the step of forming the modified layer, the reference position is irradiated with a laser beam, and in the step of forming the linear processing trace, the step of separating from the reference position toward the indexing feed direction is equivalent to The position of the predetermined distance irradiates the laser beam. Invention effect

According to the present invention, although the modified layer formed inside the substrate of the confirmation wafer is difficult to visually recognize, it is because when the back of the metal foil is processed by the laser beam, the metal foil is placed in the thickness direction of the metal foil. It melts and changes color on the front side and appears on the front side as a linear processing trace, so it can be easily visually recognized by the user.

Therefore, the user can easily grasp the position of the modified layer (that is, the irradiation position of the laser beam when the modified layer is formed) from the appearance of the confirmation wafer based on the linear processing trace. Therefore, because the user can obtain the irradiation position of the laser beam during the formation of the modified layer, and the part of the laser beam that does not contribute to the formation of the modified layer, the user can directly reach the front side of the substrate or in the modification. The positional relationship of the surface damage formed on the metal foil by reflection, scattering, refraction, etc. on the quality layer or the cracks formed on the periphery of the modified layer, so that the occurrence of surface damage (that is, the laser beam’s impact on the substrate) Positive influence). As a result, the user can easily confirm the frontal influence of the laser beam irradiation on the workpiece. Therefore, the user can, for example, select appropriate processing conditions in the laser processing device and detect abnormalities in the laser processing device.

Preferably, in this confirmation method, the linear processing trace forming step is performed before the reforming layer forming step. In this regard, depending on the relationship between the formation position of the modified layer and the formation position of the linear processing traces, if the modified layer is formed first, the irradiation of the laser beam used to form the linear processing traces may be hindered by the modified layer Yu. It is possible to prevent such a situation by performing the linear processing trace forming step first.

Preferably, in the confirmation method, the above-mentioned reference position setting step is performed before the linear processing trace forming step. Thereby, the formation position of the modified layer can be set as the reference position, and the linear processing trace and the modified layer can be formed according to the reference position. This makes it easier to appropriately set the positional relationship between the linear processing trace and the modified layer.

The confirmation method of one embodiment of the present invention (this confirmation method) is to irradiate a laser beam with a wavelength penetrating the workpiece from the back side of the workpiece by a laser processing device, and confirm that the workpiece is The method of confirming the positive influence of the laser beam on the processed object when the modified layer is formed inside. The following describes the steps of this confirmation method.

(1) Steps to prepare wafers for confirmation In this confirmation method, a confirmation wafer that is different from the workpiece actually used to manufacture the product (wafer) is used to confirm the frontal influence of the laser beam on the workpiece.

As shown in FIGS. 1 and 2, the confirmation wafer 1 has a substrate 2 formed in a disc shape, and a metal foil 5 provided on the front surface of the substrate 2. As shown in FIG. 2, the base material 2 has a front surface 3 and a back surface 4. A metal foil 5 is formed on the front surface 3 of the substrate 2. A recess 9 showing the crystal orientation of the confirmation wafer 1 is provided on the outer periphery of the substrate 2. A chamfering process may be performed on the outer periphery of the base material 2 (refer to FIG. 6).

In the wafer preparation step for confirmation, for example, round as-sliced wafers are ground and ground to a predetermined thickness after removing deformation elements including warpage and swelling. The recess 9 is formed, and the substrate 2 is obtained. In addition, the metal foil 5 is laminated on the front surface 3 of the base material 2 by, for example, vapor deposition. In this way, the wafer 1 for confirmation is prepared.

Furthermore, the material of the base material 2 is preferably a material that is the same as the material to be processed that is actually used to manufacture the product, such as silicon. The metal foil 5 is a tin film formed by forming tin into a film, for example, and its thickness is preferably about several hundreds of nm.

(2) Reference position setting step, linear processing trace forming step, and modified layer forming step Next, a reference position setting step, a linear processing trace forming step, and a modified layer forming step are performed. The reference position setting step is to set a reference position on the confirmation wafer 1, and the linear processing trace forming step is to form the front surface of the metal foil 5. For linear processing traces, the aforementioned modified layer forming step is to form a modified layer inside the base material 2. First, the configuration of the laser processing apparatus used in these steps will be explained.

As shown in FIG. 3, the laser processing device 10 includes a rectangular parallelepiped base 11, a standing wall 13 erected on one end of the base 11, and a control unit 51 that controls each member of the laser processing device 10.

A holding table moving mechanism 14 that moves the holding table 43 is provided on the upper surface of the base 11. The holding table moving mechanism 14 is provided with: a holding table section 40 having a holding table 43, an indexing feed section 20 that moves the holding table 43 in the indexing feed direction (Y-axis direction), and The machining feed section 30 that holds the table 43 moving in the machining feed direction (X-axis direction).

The indexing feed unit 20 includes a pair of guide rails 23 extending in the Y-axis direction, a Y-axis table 24 placed on the guide rail 23, a ball screw 25 extending parallel to the guide rail 23, and a ball screw 25 that rotates the ball screw 25. Drive motor 26.

The pair of guide rails 23 are arranged on the upper surface of the base 11 parallel to the Y-axis direction. The Y-axis table 24 is slidably installed on a pair of guide rails 23 along these guide rails 23. The machining feed section 30 and the holding table section 40 are placed on the Y-axis table 24.

The ball screw 25 is screwed to a nut portion (not shown) provided on the lower surface side of the Y-axis table 24. The drive motor 26 is connected to one end of the ball screw 25 and drives the ball screw 25 to rotate. By rotationally driving the ball screw 25, the Y-axis table 24, the processing feed section 30, and the holding table section 40 are moved along the guide rail 23 in the indexing feed direction (Y-axis direction).

The processing feed portion 30 includes a pair of guide rails 31 extending in the X-axis direction, an X-axis table 32 placed on the guide rail 31, a ball screw 33 extending parallel to the guide rail 31, and a ball screw 33 that rotates the ball screw 33. Drive motor 35. The pair of guide rails 31 are arranged on the upper surface of the Y-axis table 24 parallel to the X-axis direction. The X-axis table 32 is slidably installed on a pair of guide rails 31 along these guide rails 31. The holding table part 40 is placed on the X-axis table 32.

The ball screw 33 is screwed to a nut portion (not shown) provided on the lower surface side of the X-axis table 32. The drive motor 35 is connected to one end of the ball screw 33 and rotates the ball screw 33. By rotationally driving the ball screw 33, the X-axis table 32 and the holding table portion 40 are moved along the guide rail 31 in the machining feed direction (X-axis direction).

The holding table part 40 has a holding table 43, four clamp parts 45, and a θ table 47. The holding table 43 is used to suck and hold the confirmation wafer 1 or the processed object. The four clamp parts 45 are installed in the holding table. Around the table 43, the aforementioned θ table 47 supports and holds the table 43. The θ stage 47 is installed on the upper surface of the X-axis stage 32 so as to be rotatable in the XY plane. The holding table 43 is formed in a circular plate shape, and is installed on the θ table 47.

On the upper surface of the holding table 43, a holding surface made of porous ceramics is formed. This holding surface is connected to the suction source (not shown). The four clamp parts 45 clamp and fix the ring frame from four directions when the holding table 43 has already held the workpiece provided with the ring frame.

A laser processing unit 12 for laser processing a workpiece is provided on the front surface of the upright wall portion 13 erected behind the holding table moving mechanism 14. The laser processing unit 12 has a processing head 18 that irradiates a laser beam to the confirmation wafer 1 or the like held on the holding table 43 and an arm 17 that supports the processing head 18.

The optical system of the laser processing unit 12 is provided in the arm portion 17 and the processing head 18. As shown in FIG. 4, the processing head 18 includes an oscillator 53 that generates a laser, and a condenser lens 54 that condenses the laser beam oscillated by the oscillator 53. The processing head 18 condenses the laser beam L output from the oscillator 53 by the condensing lens 54 and irradiates it to the confirmation wafer 1 and the like that have been held on the holding table 43.

The laser beam L emitted from the processing head 18 is, for example, a pulsed laser beam, and has a wavelength that is transparent to the confirmation wafer 1. The condensing point P obtained by condensing this laser beam L can be arranged at an arbitrary height (position along the Z-axis direction).

The control unit 51 is an integrated control of each component of the laser processing apparatus 10. The control unit 51 has a processor that executes various processes. The detection results from various detectors (not shown) can be input to the control component 51.

(2-1) Steps for setting the reference position Next, the reference position setting procedure using this laser processing apparatus 10 will be described. This step is performed after the wafer preparation step for confirmation.

In this step, first, the user places the confirmation wafer 1 on the holding table 43 so that the back surface 4 of the base material 2 shown in FIG. 2 is exposed upward. In response to this, the control unit 51 controls the suction source to suck and hold the metal foil 5 of the confirmation wafer 1 on the holding table 43.

After that, as shown in FIG. 5, the control unit 51 sets the position where the modified layer is to be formed in the confirmation wafer 1 as the reference position B. Since neither dicing lanes nor components are formed in the confirmation wafer 1, the reference position B can be set anywhere, and the angle adjustment of the confirmation wafer 1 by the θ stage 47 becomes unnecessary.

For example, the control unit 51 controls the indexing and feeding unit 20, and sets the position of the indexing and feeding direction (Y-axis direction) of the holding table 43 holding the confirmation wafer 1 to a preset first position. At this time, the irradiation position of the laser beam L from the processing head 18 to the confirmation wafer 1 becomes the reference position B.

(2-2) Steps for forming linear processing traces In this step, the laser beam L is positioned at a position separated by a predetermined distance from the reference position B toward the indexing feed direction orthogonal to the processing feed direction.

That is, the control unit 51 moves the holding table 43 holding the confirmation wafer 1 by controlling the indexing feed unit 20, and transfers the laser beam L from the processing head 18 to the confirmation wafer 1 The irradiation position of is set to a position that is separated by a predetermined offset distance d (refer to FIG. 7) from the reference position B toward the + side (+Y axis direction) in the indexing feed direction.

In this state, as shown in FIG. 6, the control unit 51 controls the optical system of the processing head 18, and positions the focus point P of the processing head 18 to the substrate 2 and the metal foil in the confirmation wafer 1. 5 interface. Then, the control module 51 irradiates the laser beam L from the processing head 18 toward the confirmation wafer 1 from the back side 4 side, and controls the processing feed unit 30 so that the holding table 43 holding the confirmation wafer 1 is shown as an arrow As shown by A, it moves along the processing feed direction so that the processing head 18 relatively moves with respect to the confirmation wafer 1 along the processing feed direction. Thereby, the back surface of the metal foil 5 can be processed by the laser beam, and the metal foil can be melted in the thickness direction of the metal foil 5, and as shown in FIG. 7, the reference position B on the front surface of the metal foil 5 is + On the Y-axis direction side, a first linear processing trace M1 is formed as a trace where the metal foil 5 is melted by the irradiation of the laser beam L.

Next, the control unit 51 sets the irradiation position of the laser beam L from the processing head 18 to the confirmation wafer 1 toward the-side (-Y axis direction) in the indexing feed direction, and sets it to be separated from the reference position B The position corresponding to the offset distance d is set, and the laser beam L is irradiated and the processing feed of the holding table 43 is performed in the same manner as when the first linear processing trace M1 is formed.

Thereby, the second linear processing trace M2 can be formed on the -Y axis direction side of the reference position B on the front surface of the metal foil 5. In this way, in the linear processing trace forming step, two linear processing traces M1 and M2 can be formed substantially parallel to the reference position B on both sides of the reference position B. The linear processing traces M1 and M2 can be confirmed from the front side of the metal foil 5 by melting the metal foil 5 in the thickness direction of the metal foil 5 and discoloring the front side by the irradiation of the laser beam L. Furthermore, it is preferable that the interval between the processing trace M1 and the processing trace M2 is set to be the same as the width of the cutting path of the workpiece to be actually formed with the modified layer. By this, it is possible to grasp at a glance whether the range of influence on the front of the workpiece caused by the irradiation of the laser beam falls within the cutting path.

In addition, the wavelength of the laser beam L in the linear processing mark forming step is, for example, 1064 nm, the output is, for example, 0.2 W, and the moving speed of the processing feed portion 30 is, for example, 500 mm/sec.

(2-3) Steps for forming modified layer In this step, the control unit 51 forms a modified layer on the confirmation wafer 1 along the reference position B.

That is, the control unit 51 controls the indexing and feeding part 20 to move the holding table 43 holding the confirmation wafer 1 and irradiate the laser beam L from the processing head 18 to the confirmation wafer 1 The position is set at the reference position B.

In this state, as shown in FIG. 8, the control unit 51 controls the optical system of the processing head 18 and positions the condensing point P of the processing head 18 inside the substrate 2 in the confirmation wafer 1. Then, the control module 51 irradiates the laser beam L from the processing head 18 toward the confirmation wafer 1 from the back side 4 side, and controls the processing feed unit 30 so that the holding table 43 follows the direction indicated by arrow A The processing feed direction is moved so that the processing head 18 moves relative to the confirmation wafer 1 along the processing feed direction.

After that, the control unit 51 changes the height of the focus point P of the processing head 18 inside the substrate 2, and similarly implements the laser beam L irradiation and maintains the processing feed of the table 43.

Thereby, as shown in FIG. 9, the modified layer T can be formed in the base material 2 along the reference position B shown in FIG. 7. In addition, the wavelength of the laser beam L in the reforming layer forming step is, for example, 1064 nm, the output of the laser beam L is, for example, 1.5 W, and the moving speed of the processing feed unit 30 is, for example, 700 mm/sec.

(3) Confirmation steps In this step, the user confirms the influence on the front surface of the metal foil 5 caused by the laser beam L irradiated in the reforming layer forming step based on the positions of the linear processing traces M1 and M2.

That is, in the reforming layer forming step, the laser beam L is irradiated from the back side 4 side of the base material 2 to position the condensing point P inside the base material 2. At this time, a part of the laser beam L that does not contribute to the formation of the modified layer may directly reach the front surface 3 side of the base material 2, or may be caused by a crack in the modified layer or formed in the periphery of the modified layer. It is reflected, scattered, and refracted to reach the front surface 3 side of the base material 2. In this way, the laser beam reaching the front side of the base material 2 may have an adverse effect on the front surface elements on the workpiece actually used for manufacturing the product. In addition, in the confirmation wafer 1, the laser beam reaching the front side of the substrate 2 in this way leaves a surface damage (laser damage) LD on the front surface of the metal foil 5 as shown in FIG. 9. In this step, the user observes the surface damage LD. In this confirmation step, the confirmation wafer 1 is removed from the holding table 43 and the surface damage LD is confirmed from the front side of the metal foil 5 laminated on the front surface of the base material 2.

As described above, in this confirmation method, the laser beam L is irradiated to two positions separated by a predetermined offset distance from the reference position B in the linear processing trace forming step, and the confirmation wafer Two linear processing traces M1 and M2 are formed on the front surface of the metal foil 5 of 1. In addition, by irradiating the laser beam L along the reference position B, a modified layer T is formed between the two linear processing traces M1 and M2.

Here, although the modified layer T formed inside the base material 2 is difficult to visually recognize, it is because the linear processing marks M1 and M2 on both sides of the metal foil 5 are clearly formed as melting marks of the metal foil 5 , So it can be easily visually recognized by users.

Therefore, the user can easily grasp the position of the modified layer T from the appearance of the confirmation wafer 1 based on the linear processing traces M1 and M2, that is, the irradiation position of the laser beam L when the modified layer T is formed. Therefore, the user can obtain the positional relationship between the irradiation position of the laser beam L during the formation of the modified layer T and the surface damage LD formed on the metal foil 5 by the laser beam that has reached the front surface of the substrate 2 (Distance, etc.), so the occurrence of surface damage LD, that is, the influence of light leakage on the front surface 3 of the substrate 2 can be appropriately confirmed. As a result, the user can easily confirm the frontal influence of the irradiation of the laser beam L on the workpiece. Therefore, the user can, for example, select appropriate processing conditions in the laser processing device 10 and detect abnormalities in the laser processing device 10. When it is confirmed on the front surface of the metal foil 5 that the laser damage LD is formed on the outer side of the pair of linear processing marks M1 and M2 during the reforming layer forming step, for example, the laser beam L during the reforming layer formation The output is reduced, and the position of the focusing point, repetition frequency, processing feed rate, pulse width, etc. are changed to appropriately change the processing conditions. On the other hand, when a plurality of laser damages LD deviate from the center of the pair of linear processing traces M1, M2, that is, from the position of the modified layer to one of the linear processing traces, it is determined that there is a deviation of the optical axis, for example It is possible to check the optical system of the laser processing device 10 and so on.

In addition, in this embodiment, the linear processing trace forming step is performed before the reforming layer forming step. In this regard, according to the relationship between the formation position (reference position B) of the modified layer T and the formation positions of the linear processing traces M1 and M2, if the modified layer T is formed first, there will be used to form the linear processing traces M1 and M2. The irradiation of the laser beam L may be hindered by the reforming layer T, but by performing the linear processing trace forming step as in the present embodiment, such a situation can be prevented.

In addition, in the present embodiment, the reference position setting step has been performed before the linear processing trace forming step. Thereby, the predetermined position for forming the modified layer T can be set as the reference position B, and the linear processing traces M1 and M2 and the modified layer T can be formed according to the reference position B. Thereby, it becomes easier to form the modified layer T between the linear processing traces M1 and M2.

Furthermore, in the present embodiment, two (two) linear machining marks M1 and M2 are formed at positions shifted from the reference position B in the +Y axis direction and the -Y axis direction by the offset distance d . At this time, it is also possible to form the first linear processing trace M1 by processing and feeding the processing feed portion 30 from the +X side to the -X side, and then, by moving the holding table 43 in the -Y axis direction, and The processing feed portion 30 is processed and fed from the −X side to the +X side to form the second linear processing trace M2.

Alternatively, when the processing head 18 is configured to irradiate two laser beams L at the same time, two linear processing traces M1 and M2 may be formed at the same time.

In addition, as shown in FIG. 10, one linear machining trace M may be formed only on one side of the indexing feed direction of the reference position B. In this configuration, the modified layer T can be grasped from the appearance of the confirmation wafer 1 based on the visually recognizable linear processing trace M and the positional relationship (offset distance d) between the linear processing trace M and the reference position B The irradiation position of the laser beam L at the time of formation.

In the step of forming the modified layer, the control unit 51 does not need to irradiate the laser beam L from one end to the other end of the outer periphery of the confirmation wafer 1. Among them, it is preferable to form the modified layer T having a length equal to or less than the two linear processing traces M1 and M2 formed in the linear processing trace forming step.

In this embodiment, although the linear processing trace forming step is performed before the reforming layer forming step, the linear processing trace forming step may be performed after the reforming layer forming step.

In addition, the reference position setting step performed in this embodiment does not necessarily need to be performed. For example, it is also possible to perform the linear processing trace forming step on any two positions in the confirmation wafer 1 to form two linear processing traces M1 and M2, and to perform the modified layer forming step on the intermediate position. The reforming layer T is formed.

In this embodiment, in the reforming layer forming step, the height of the condensing point P in the interior of the base material 2 is changed, and the irradiation of the laser beam L and the processing feed of the holding table 43 are performed twice. Instead, in the reforming layer forming step, the irradiation of the laser beam L and the processing feed of the holding table 43 may be performed only once, or three or more times.

1: Confirmation wafer 2: substrate 3: positive 4: back 5: Metal foil 9: Notch 10: Laser processing device 11: Abutment 12: Laser processing unit 13: Standing wall 14: Keep the workbench moving mechanism 17: Arm 18: Processing head 20: Indexing feed section 23, 31: rail 24: Y-axis table 25, 33: Ball screw 26, 35: drive motor 30: Processing Feeding Department 32: X axis table 40: Keep the workbench department 43: keep the workbench 45: Fixture Department 47: Theta workbench 51: control components 53: Oscillator 54: Condenser lens A: Arrow B: Reference position L: Laser beam P: Spotlight M: Linear processing trace M1: 1st linear processing trace M2: 2nd linear processing trace LD: Surface damage (laser damage) T: modified layer d: offset distance X,+X,-X,Y,+Y,-Y,Z: direction

Fig. 1 is a perspective view of a confirmation wafer. Fig. 2 is a partially enlarged cross-sectional view of a wafer for confirmation. Fig. 3 is a perspective view showing the structure of the laser processing device. Fig. 4 is a schematic diagram showing the structure of the processing head of the laser processing device. Fig. 5 is a plan view showing a reference position set on a wafer for confirmation. FIG. 6 is a cross-sectional view showing the condensing point of the laser beam in the step of forming the linear processing trace. FIG. 7 is an explanatory diagram showing the linear processing traces of the metal foil formed on the confirmation wafer by the linear processing trace forming step. Fig. 8 is a cross-sectional view showing the condensing point of the laser beam in the reforming layer forming step. FIG. 9 is an explanatory diagram showing the traces of linear processing and the surface damage formed on the metal foil in the step of forming a modified layer. FIG. 10 is an explanatory diagram showing another form of linear processing traces formed on the metal foil by the linear processing trace forming step.

M1: 1st linear processing trace

M2: 2nd linear processing trace

LD: Surface damage

T: modified layer

Claims (3)

A confirmation method is to confirm that the laser processing device is used to irradiate a laser beam with a wavelength penetrating to the workpiece from the back side of the workpiece to form a modified layer inside the workpiece. For the positive impact of the laser beam irradiation on the workpiece, the aforementioned confirmation method has the following steps: The confirmation wafer preparation step is to prepare the confirmation wafer with metal foil on the front surface of the substrate; The reforming layer forming step includes irradiating a laser with a wavelength penetrating the substrate from the back side of the substrate in a state where the condensing point has been positioned inside the substrate of the confirmation wafer Light beam, and relatively move the condensing point and the confirmation wafer in the processing and feeding direction to form a modified layer inside the substrate; In the step of forming linear processing traces, in the indexing feed direction orthogonal to the processing feed direction, at a predetermined distance from the irradiation position of the laser beam in the reforming layer forming step to condense the light The spot is positioned in the state of the interface between the substrate and the metal foil of the confirmation wafer, and a laser beam with a wavelength penetrating the substrate is irradiated from the back side of the substrate, and the condensing spot Move relative to the confirmation wafer in the processing feed direction, and form linear processing traces on the front surface of the metal foil; and In the confirming step, after the modified layer forming step and the linear processing trace forming step are performed, based on the position of the linear processing trace, it is confirmed that the laser beam irradiated in the modified layer forming step causes the The positive effect of the metal foil. Such as the confirmation method of claim 1, wherein the reforming layer forming step is performed after the linear processing trace forming step is performed. For example, the confirmation method of claim 1 or 2 further includes a reference position setting step. The aforementioned reference position setting step is to form the modified layer on the confirmation wafer after the confirmation wafer preparation step The position is set as the reference position, In the step of forming the modified layer, the reference position is irradiated with a laser beam, In the linear processing mark forming step, a laser beam is irradiated to a position separated from the reference position by the predetermined distance in the indexing feed direction.

Images