TWI862560B - Inspection substrate and inspection method - Google Patents

Abstract

[Topic] To quantitatively evaluate the area where light leakage may reach, an inspection substrate is provided for inspecting light leakage of a laser beam. [Solution] An inspection substrate is provided for inspecting light leakage of a laser beam, the inspection substrate comprising: a surface on one side, irradiated with a laser beam having a wavelength that penetrates the inspection substrate; a surface on the other side, opposite to the surface on the one side; a cutting path set on the surface on the other side; a plurality of first inspection wirings, each along the cutting path and arranged at different distances from the cutting path on the surface on the other side; and a plurality of first electrode pads, two or more of which are provided on each of the plurality of first inspection wirings on the surface on the other side, and separately arranged in the direction along the cutting path in each of the plurality of first inspection wirings.

Description

Inspection substrate and inspection method

The present invention relates to an inspection substrate for inspecting light leakage of laser beam when processing a workpiece with laser beam, and an inspection method for inspecting light leakage of laser beam using the inspection substrate.

A disk-shaped wafer is known in which semiconductor elements are formed in each region divided by a plurality of predetermined dividing lines (i.e., scribe lines) arranged in a grid shape. In order to divide the wafer along the scribe lines and manufacture semiconductor chips, for example, a laser processing device is used.

For example, a laser processing device is used to position the focal point of a pulsed laser beam of a wavelength that can penetrate the wafer inside the wafer, and the laser beam is irradiated from the back side of the wafer along the scribe line on the front side of the wafer. As a result, multiphoton absorption occurs near the focal point, and a modified layer with reduced mechanical strength is formed along the scribe line. Thereafter, an external force is applied to the wafer, and the wafer is divided along the scribe line starting from the modified layer.

When forming a modified layer, multiple modified layers are usually formed at different depths of the wafer. For example, the depth position of the focal point is positioned at a predetermined depth on the front side of the wafer, and a laser beam is irradiated along one cutting path. By irradiating the laser beam once along the cutting path (i.e., irradiation of the laser beam in the first pass), the first modified layer is formed.

After that, after the depth position of the focal point is moved toward the back side by a predetermined distance, the laser beam is irradiated once again along the same dicing path (i.e., the irradiation of the laser beam in the second pass) to form the second modified layer. Similarly, the depth position of the focal point is moved toward the back side by a predetermined distance and the irradiation of the laser beam is repeated to form multiple (e.g., 2 to 5) modified layers inside the wafer.

When forming the modified layer, although the laser beam is mainly absorbed by the wafer at the focal point located at a predetermined depth, a portion of the laser beam may be refracted or reflected by the modified layer located on the front side of the modified layer or by cracks extending from the modified layer.

Assuming that a portion of the laser beam becomes leakage light (i.e., light that reaches the semiconductor device beyond the targeted irradiation area (i.e., the scribe line)) through refraction or reflection, the leakage light will reach the semiconductor device formed by each area on the front side of the wafer divided by multiple scribe lines. In this case, there is a concern that the semiconductor device will be damaged by the leakage light. Therefore, it is necessary to select the irradiation conditions of the laser beam (i.e., the laser processing conditions) in such a way that the leakage light does not reach the semiconductor device.

Therefore, there is a known method of forming a coating layer made of tin (Sn) or oil-based ink on the front side of a wafer, and then irradiating a laser beam from the back side of the wafer to confirm the light leakage reaching the front side of the wafer (for example, refer to Patent Document 1) [Known Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2017-216413

[Problem to be solved by the invention] However, in the method described in Patent Document 1, the deteriorated area is only observed by the laser beam reaching the coating layer, and there is no method for quantitatively evaluating the area reached by the leakage light.

The present invention is made in view of this problem, and its purpose is to provide an inspection substrate for inspecting the light leakage of a laser beam in order to quantitatively evaluate the area where the light leakage may reach.

[Technical means for solving the problem] According to one aspect of the present invention, there is provided an inspection substrate for inspecting light leakage of a laser beam, the inspection substrate comprising: a surface on one side, irradiated with the laser beam having a wavelength that penetrates the inspection substrate; a surface on the other side, opposite to the surface on the one side; a cutting path set on the surface on the other side; a plurality of first inspection wirings, each along the cutting path and arranged at different distances from the cutting path on the surface on the other side; and a plurality of first electrode pads, two or more of which are provided on each of the plurality of first inspection wirings on the surface on the other side, and separately arranged in the direction along the cutting path in each of the plurality of first inspection wirings. Preferably, the inspection substrate further includes a plurality of second inspection wirings which are separated from the plurality of first inspection wirings along the scribe line on the surface of the other side, and each of the second inspection wirings is arranged at a different distance from the scribe line along the scribe line.

According to another aspect of the present invention, an inspection method is provided, which uses an inspection substrate to inspect light leakage of a laser beam, the inspection substrate comprising: a surface on one side, which is irradiated with the laser beam having a wavelength that penetrates the inspection substrate; a surface on the other side, which is opposite to the surface on the one side; a cutting path, which is set on the surface on the other side; a plurality of first inspection wirings, each of which is along the cutting path and is arranged at a different distance from the cutting path on the surface on the other side; and a plurality of first electrode pads, which are provided on the surface on the other side for each of the plurality of first inspection wirings and are separately arranged in the direction along the cutting path in each of the plurality of first inspection wirings. The inspection method comprises: a holding step of holding the other side surface of the inspection substrate with a chuck table; a laser processing step of irradiating the laser beam from the one side surface of the inspection substrate along the cutting path to form a modified layer along the cutting path inside the inspection substrate; and a light leakage confirmation step of contacting a detector with the multiple first electrode pads provided on each of the multiple first inspection wirings after the laser processing step to confirm the presence or absence of light leakage by confirming whether the multiple first inspection wirings are broken.

[Effect of the invention] According to an inspection substrate of one aspect of the present invention, a plurality of first inspection wirings and a plurality of first electrode pads are provided on a surface on one side irradiated with a laser beam and on a surface on the other side opposite to the laser beam. Each of the plurality of first inspection wirings is arranged at a different distance from the cutting path along the cutting path. In addition, two or more of the plurality of first electrode pads are provided for each of the plurality of first inspection wirings, and are separately arranged in the direction along the cutting path in each of the plurality of first inspection wirings.

After irradiating the laser beam along the dicing street, for example, the first inspection wiring is inspected by bringing a detector (i.e., a probe) into contact with each of the two first electrode pads and energizing them. In this way, since it is possible to determine at which position of the first inspection wiring, among a plurality of first inspection wirings arranged at different distances from the dicing street, the first inspection wiring receives leakage light and is disconnected, the influence of leakage light can be quantitatively evaluated.

Referring to the accompanying drawings, an implementation method of one aspect of the present invention is described. FIG1 is a perspective view of a frame unit 1. The frame unit 1 has an inspection substrate 11 for inspecting light leakage. The inspection substrate 11 is disc-shaped, and has a circular front surface (surface on the other side) 11a and a back surface (surface on one side) 11b, and has a thickness of about 500μm to 1000μm.

The inspection substrate 11 is a wafer formed of a silicon (Si) substrate, but the inspection substrate 11 is not limited to silicon, and may be formed of semiconductor materials such as gallium arsenide (GaAs), silicon carbide (SiC), and gallium nitride (GaN), sapphire, or various glasses.

A plurality of scribe lines 13 are provided on the front surface 11a of the inspection substrate 11 so as to intersect each other. Each scribe line 13 is provided parallel to the first direction A or the second direction B perpendicular to the first direction A.

Devices 15a and inspection regions 15b are provided in each of the plurality of regions divided by the plurality of dicing streets 13. In addition, in this specification, the region where the devices 15a and inspection regions 15b are provided is referred to as a device region 15A.

For example, a plurality of elements 15a are arranged in a row along the first direction A, and a plurality of inspection regions 15b are arranged in a row along the first direction A so as to be adjacent to the row of the elements 15a in the second direction B. In this way, the plurality of elements 15a and the plurality of inspection regions 15b, each arranged in a row, are alternately arranged from one end of the element region 15A in the second direction B to the other end.

However, the arrangement of the element 15a and the inspection region 15b is not limited to the above example. A plurality of elements 15a and a plurality of inspection regions 15b may be arranged in a row along the second direction B and alternately arranged from one end of the element region 15A in the first direction A to the other end.

In addition, the plurality of components 15a and the plurality of inspection regions 15b may be arranged alternately (i.e., in a checkerboard pattern) in the first direction A and the second direction B. In addition, the component 15a may not be provided in the component region 15A. When the component 15a is not provided, the inspection region 15b is provided in each region divided by the plurality of dicing streets 13.

Next, the inspection area 15b is described in detail. Fig. 2 is a top view showing a part of the device area 15A of the first embodiment in an enlarged manner. In addition, in Fig. 2, for convenience, the cutting path 13 along the first direction A is marked as a cutting path 13-1, and the cutting path 13 along the second direction B is marked as a cutting path 13-2.

2 shows two elements 15a arranged along the first direction A, two inspection regions 15b adjacent to the two elements 15a in the second direction B and arranged along the first direction A, and two more elements 15a adjacent to the two inspection regions 15b in the second direction B and arranged along the first direction A.

The inspection area 15b has a plurality of first inspection wirings 23a disposed on the front surface (the other side) 11a. Each first inspection wiring 23a is disposed along the dicing street 13-2. Each first inspection wiring 23a is a thin film wiring layer formed of a conductive material (eg, tin (Sn)).

Each of the first inspection wirings 23a has a line width and thickness that can be disconnected by a laser beam of predetermined energy. Therefore, each of the first inspection wirings 23a can be disconnected by leakage of a laser beam of predetermined energy.

For example, each first inspection wiring 23a has a line width of 10 nm to 5 μm, and has a thickness equivalent to one layer of build-up wiring provided in the element 15a (eg, a thickness of 10 nm to 1 μm).

Each of the plurality of first inspection wirings 23a (23a-1, 23a-2, 23a-3, 23a-4, and 23a-5) is arranged at a different distance from the dicing street 13-2. The first inspection wiring 23a-1 is adjacent to the dicing street 13-2.

The first inspection wiring 23a-2, 23a-3, 23a-4, and 23a-5 are arranged in this order so as to gradually move away from the first inspection wiring 23a-1. That is, the first inspection wiring 23a-2 is closest to the first inspection wiring 23a-1, and the first inspection wiring 23a-5 is farthest from the first inspection wiring 23a-1.

The plurality of first inspection wirings 23a are arranged so that adjacent lines are separated from each other by a predetermined distance. For example, each first inspection wiring 23a is separated from each other by a distance equal to one side of a substantially square first electrode pad 25a described later.

The farther the first inspection wiring 23a is from the dicing street 13-2, the shorter its length in the second direction B. That is, the length of the plurality of first inspection wirings 23a in the second direction B is such that the first inspection wiring 23a-1 is the longest and the first inspection wiring 23a-5 is the shortest.

Each of the first inspection wirings 23a is arranged in a row along the first direction A with the center position of the length in the second direction B. Therefore, both ends of the first inspection wiring 23a-1 are located outside both ends of the first inspection wiring 23a-2, and both ends of the first inspection wiring 23a-2 are located outside both ends of the first inspection wiring 23a-3.

Furthermore, both ends of the first inspection wiring 23a-3 are located outside the both ends of the first inspection wiring 23a-4, and both ends of the first inspection wiring 23a-4 are located outside the both ends of the first inspection wiring 23a-5.

The first electrode pads 25 a are arranged at two positions (more specifically, both ends in the longitudinal direction) separated in the direction of the scribe line 13 - 2 in each of the first inspection wirings 23 a. The first electrode pad 25a has, for example, a substantially square shape of several dozen μm, and one side thereof is located at an end of the first inspection wiring 23a in the longitudinal direction.

The first electrode pad 25a is a layer formed of, for example, tin, and has the same thickness as the first inspection wiring line. However, one side of the first electrode pad 25a is wider than the line width of the first inspection wiring line 23a.

A plurality of second inspection wirings (23b-1, 23b-2, 23b-3, 23b-4, and 23b-5) are arranged at positions separated from the plurality of first inspection wirings 23a along the dicing street 13-2. Each of the plurality of second inspection wirings 23b is arranged at a position with a different distance from the dicing street 13-2. The second inspection wiring 23b-1 is adjacent to the dicing street 13-2.

The second inspection wiring 23b-2, 23b-3, 23b-4 and 23b-5 are arranged in this order so as to gradually move away from the second inspection wiring 23b-1. That is, the second inspection wiring 23b-2 is closest to the second inspection wiring 23b-1, and the second inspection wiring 23b-5 is farthest from the second inspection wiring 23b-1. The plurality of second inspection wirings 23b are also arranged in a manner such that each adjacent line is separated from each other by a predetermined distance, similar to the plurality of first inspection wirings 23a.

The second inspection wiring 23b also becomes shorter as it is farther from the dicing street 13-2. In addition, each second inspection wiring 23b is arranged in a row along the first direction A with the center position of the length in the second direction B thereof.

Second electrode pads 25b are also arranged at both ends of each of the second inspection wirings 23b. The second electrode pads 25b have the same shape as the first electrode pads 25a and are formed of tin. The second electrode pad 25b is also arranged so that one side thereof is located at the end of the second inspection wiring 23b in the longitudinal direction.

The plurality of first inspection wirings 23a and the plurality of second inspection wirings 23b are alternately arranged along the dicing street 13-2 in a state of being separated from each other in the second direction B. In addition, in order to arrange the plurality of first inspection wirings 23a and the plurality of second inspection wirings 23b as densely as possible, the first electrode pad 25a and the second electrode pad 25b adjacent to each other in the second direction B are separated by a distance smaller than the length of one side of one first electrode pad 25a, for example.

As a more specific example, the first electrode pad 25a and the second electrode pad 25b adjacent to each other in the second direction B are separated by a length equal to the spot diameter of the laser beam. Thus, in the vicinity of the dicing street 13-2 of the inspection area 15b, a plurality of first inspection wirings 23a and a plurality of second inspection wirings 23b are densely arranged from one side (e.g., the positive direction side) in the second direction B to the other side (e.g., the negative direction side).

Similarly, in one inspection area 15b, near the scribe line 13-2 located on the opposite side to the scribe line 13-2 in the first direction A, a plurality of first inspection wirings 23a and a plurality of second inspection wirings 23b are densely arranged from one side in the second direction B to the other side.

Furthermore, in the same inspection region 15b, near the dicing street 13-1 located on one side in the second direction B, a plurality of first inspection wirings 23a and a plurality of second inspection wirings 23b are alternately and densely arranged from one side in the first direction A to the other side.

Furthermore, in the same inspection region 15b, near the dicing street 13-1 located on the other side in the second direction B, a plurality of first inspection wirings 23a and a plurality of second inspection wirings 23b are alternately and densely arranged from one side in the first direction A to the other side.

2 , the plurality of first inspection wirings 23 a and the plurality of second inspection wirings 23 b are represented simply as inspection wirings 23 , and similarly, the plurality of first electrode pads 25 a and the second electrode pads 25 b are represented simply as electrode pads 25 .

1 to explain the frame unit 1. On the front side 11a of the inspection substrate 11, there is an outer peripheral surplus area 15B where neither the device 15a nor the inspection area 15b is provided, like the outer periphery surrounding the device area 15A.

A notch 11c indicating the crystal orientation of the wafer is provided at a portion of the outer peripheral end of the inspection substrate 11. Alternatively, other marks such as an orientation flat surface may be provided instead of the notch 11c.

The inspection substrate 11 is fixed to the opening of the metal ring frame 19 through the dicing film 17, for example. The dicing film 17 is a film made of a ductile resin. The dicing film 17 has a layered structure, and the layered structure includes an adhesive layer (not shown) made of an adhesive resin and a base layer (not shown) made of a non-adhesive resin.

The adhesive layer is, for example, a UV-curable resin layer, and is provided on the entire surface of one side of the base layer. When the adhesive layer is irradiated with UV rays, the adhesive force of the adhesive layer is reduced, and it becomes easy to peel the dicing film 17 from the inspection substrate 11.

The annular frame 19 has an opening with a diameter larger than that of the inspection substrate 11. With the inspection substrate 11 disposed in the opening, the frame unit 1 is formed by attaching the adhesive layer side of the dicing film 17 to the front surface 11a of the inspection substrate 11 and one surface of the annular frame 19.

Next, the inspection method for inspecting light leakage is described using FIG. 3, FIG. 4, FIG. 5 (A), FIG. 5 (B), and FIG. 6. In addition, FIG. 6 is a flow chart showing the inspection of light leakage. In the inspection method of the first embodiment, first, the frame unit 1 is held on the laser processing device 10 by the chuck table 12 (holding step (S10)). FIG. 3 is a partial cross-sectional side view of the frame unit 1 and the laser processing device 10.

The laser processing device 10 has a chuck table 12. A disk-shaped porous plate formed of a material such as porous ceramic is provided on the surface side of the chuck table 12. The porous plate is connected to a flow path (not shown) provided inside the chuck table 12 and is connected to a suction source (not shown) such as an ejector. The negative pressure generated by the suction source generates suction force on the surface of the porous plate (i.e., the holding surface 12a).

A plurality of clamping units 14 are fixed to the outer peripheral side surface of the chuck table 12. For example, when the chuck table 12 is viewed from above, one clamping unit 14 is disposed at each of the 12 o'clock direction, the 3 o'clock direction, the 6 o'clock direction, and the 9 o'clock direction of the clock hand.

An X-axis moving unit (not shown) and a Y-axis moving unit (not shown) are provided below the chuck table 12. The X-axis moving unit and the Y-axis moving unit each have a ball screw mechanism, which can move the chuck table 12 in the X-axis direction and the Y-axis direction. In addition, the chuck table 12 is connected to a rotation drive source (not shown) such as a motor, and can rotate with a straight line roughly parallel to the Z-axis direction (vertical direction) as a rotation axis.

A processing head 16 constituting a laser beam irradiation unit is provided above the chuck stage 12. A pulsed laser beam L having a wavelength that penetrates the inspection substrate 11 is irradiated from the processing head 16 toward the holding surface 12a in a substantially vertical direction.

In the holding step (S10), first, the frame unit 1 is placed on the holding surface 12a with the back surface 11b of the inspection substrate 11 facing upward. In this state, the suction source is operated to apply negative pressure to the holding surface 12a.

Furthermore, the position of the ring frame 19 is fixed by the clamping unit 14. Thus, the front surface (the other surface) 11a side located on the opposite side to the back surface (the one surface) 11b is held by the chuck table 12 through the dicing film 17.

Next, the laser processing device 10 is used to irradiate the back surface (one side) 11b side with a laser beam L along the cut line 13 of the inspection substrate 11 (laser processing step (S20)). First, the rotary drive source is operated, and the direction of the chuck table 12 is adjusted so that the cut line 13 of the inspection substrate 11 becomes parallel to the X-axis direction.

Then, the position of the chuck table 12 is adjusted by the X-axis moving unit so that the lower end of the processing head 16 is located on the extension line of one side (e.g., the −X direction) of the X-axis direction of one cutting street 13. Then, the laser beam L is irradiated from the processing head 16 to the back side 11b of the inspection substrate 11 so that the focal point of the laser beam L is positioned inside the inspection substrate 11.

Thereafter, with the focal point of the laser beam L irradiated from the back surface 11b of the inspection substrate 11 positioned inside the inspection substrate 11, the X-axis moving unit is operated to move the chuck table 12 to the other side (eg, +X direction) of the X-axis direction.

While the processing head 16 is moved relative to the chuck table 12 , the laser beam L is irradiated along the scribe line 13 (first pass), thereby forming a first modified layer 11 d along the scribe line 13 inside the inspection substrate 11 .

After the first pass, the depth position of the focal point is moved toward the back surface 11b by a predetermined distance, and then the chuck table 12 is moved toward one side (eg, the -X direction) in the X-axis direction along the same cutting path 13 (second pass). Thus, the second modified layer 11d is formed.

After the second pass, the depth position of the focal point is moved further toward the back surface 11b by a predetermined distance, and then the chuck table 12 is moved toward the other side (for example, the +X direction) in the X-axis direction along the same cutting path 13 (third pass). Thus, the third modified layer 11d is formed.

In the same manner, the same scribe line 13 is irradiated with the laser beam L in the fourth and fifth passes, thereby forming the fourth and fifth modified layers 11d. Thereafter, the irradiation with the laser beam L is temporarily stopped. The laser processing conditions are set, for example, as follows.

Wavelength of laser beam L: 1342nm Pulse repetition frequency: 90kHz Average output: 1.9W Spot diameter: 10μm to 20μm Processing feed speed: 700mm/s

Next, the chuck table 12 is indexed and fed in the Y-axis direction by a predetermined indexing amount, and the lower end of the processing head 16 is positioned on another cutting path 13 adjacent to the cutting path 13 just processed in the Y-axis direction.

Then, the laser beam L is irradiated from the first pass to the fifth pass along another scribe line 13. In this way, five modified layers 11d are formed along all scribe lines 13 parallel to each other in one direction.

Thereafter, the chuck table 12 is rotated 90 degrees, and the laser beam L is irradiated from the first pass to the fifth pass along all the cutting paths 13 parallel to the other direction orthogonal to the one direction. Thus, five modified layers 11d are formed along each of all the cutting paths 13. In addition, the number of modified layers 11d is not limited to five. The number of modified layers 11d may be a predetermined number of two or more.

However, when the laser beam L is irradiated, a part of the laser beam L is refracted or reflected, and leakage light D (see FIG. 4 ) (ie, light that exceeds the target irradiation area (dicing street 13 ) and reaches the element 15 a ) may be generated.

For example, when the second modified layer 11d is formed, a portion of the laser beam L is refracted or reflected due to cracks 11e formed from the first modified layer 11d toward the second modified layer 11d, thereby generating leakage light D.

Fig. 4 is an enlarged view of the area C of Fig. 3. Fig. 4 shows the leakage light D generated when the second layer 11d is formed. If the leakage light D with a predetermined energy exceeds the cutting street 13-2 and reaches the first inspection wiring 23a and the like in the inspection area 15b, the first inspection wiring 23a and the like may be damaged, for example, broken.

Therefore, after the laser processing step (S20), the disconnection of the inspection wiring 23 is confirmed (light leakage confirmation step (S30)). To this end, first, after the adhesive film (not shown) for pasting replacement is attached to the back surface (one side) 11b of the inspection substrate 11, the dicing adhesive film 17 is irradiated with ultraviolet light to reduce the adhesive force of the adhesive layer. After that, the dicing adhesive film 17 is peeled off from the inspection substrate 11 using a peeling device (not shown).

In the light leakage checking step ( S30 ), a disconnection of the inspection wiring 23 is checked using an inspection jig (not shown) such as a wafer prober. The inspection jig has a plurality of probes (ie, probes) that can contact the electrode pad 25 .

In the light leakage checking step (S30), for example, the first probe of the inspection jig is brought into contact with the first electrode pad 25a at one end of the first inspection wiring 23a-1, and the second probe is brought into contact with the first electrode pad 25a at the other end of the first inspection wiring 23a-1. In this state, a current flows between the first probe and the second probe.

For example, if part of the inspection wiring 23 is deteriorated due to receiving the leakage light D, and the conductivity of the inspection wiring 23 is significantly reduced, the current measurable within the predetermined measurement range will not flow between the first detector and the second detector. Therefore, it can be determined that the inspection wiring 23 is broken.

On the other hand, when a current equal to or greater than a predetermined value measurable within a predetermined measurement range flows between the first detector and the second detector through the first inspection wiring 23a-1, it can be determined that the first inspection wiring 23a is not disconnected.

In this way, the presence or absence of disconnection of the first inspection wiring 23a-1 can be checked using the inspection jig. In the same manner, the presence or absence of disconnection of the first inspection wirings 23a-2 to 23a-5 and the plurality of second inspection wirings 23b can also be checked.

Since the presence of a disconnection can be checked by conducting a continuity check on each inspection wiring 23, it is possible to identify at which position of the inspection wiring 23 a disconnection occurs due to receiving the leakage light D. Therefore, it is possible to quantitatively evaluate how far the influence of the leakage light D extends from the dicing street 13.

FIG5(A) is a top view showing a part of the device region 15A in an enlarged manner. FIG5(A) shows an example of the result in the light leakage confirmation step (S30). In addition, the arrow in FIG5(A) is the relative movement direction E of the laser beam L and the chuck stage 12, which is parallel to the X-axis direction of the laser processing device 10, for example.

In the example shown in FIG. 5(A), the deteriorated region 27 is formed only in the inspection region 15b on one side (e.g., the positive direction side) of the scribe line 13-2 in the first direction A. The inspection wiring 23 having the deteriorated region 27 is in a disconnected state. In addition, the deteriorated region 27 is not formed in the inspection region 15b on the other side (e.g., the negative direction side) of the scribe line 13-2 in the first direction A.

However, due to the positional misalignment between the center of the laser beam L and the optical axis of the lens of the optical system for irradiating the laser beam L or the center of the slit of the optical system, the energy distribution of the laser beam L may be offset. In this case, the leakage light D reaches a region different from the example shown in FIG. 5 (A). FIG. 5 (B) is a top view showing a partial enlargement of the device region 15A. FIG. 5 (B) shows another example of the result in the light leakage confirmation step (S30).

In the example shown in Fig. 5(B), the inspection area 15b on both sides of the dicing street 13-2 has a deteriorated area 27. The inspection wiring 23 with the deteriorated area 27 is disconnected, and the inspection wiring without the deteriorated area 27 is not disconnected.

In this way, by performing a continuity test using the inspection wiring 23 provided in the inspection area 15b, it is possible to determine at which position the inspection wiring 23 is broken due to the leakage light D. Therefore, it is possible to quantitatively evaluate how far the influence of the leakage light D extends from the dicing street 13, and at what frequency the leakage light D occurs. In addition, based on the quantitative evaluation, the irradiation conditions of the laser beam L can be corrected.

Next, the inspection substrate 11 of the second embodiment will be described. Fig. 7 is a partial enlarged view of the device region 15A of the second embodiment. The inspection substrate 11 of the second embodiment has a plurality of inspection wirings 23 on the dicing street 13-2 in addition to the inspection region 15b.

More specifically, between two inspection areas 15b arranged opposite to each other with the dicing street 13-2 sandwiched therebetween, a plurality of third inspection wirings 23c (23c-1, 23c-2, 23c-3, and 23c-4) are provided along the dicing street 13-2. The plurality of third inspection wirings 23c are arranged in a direction orthogonal to the dicing street 13-2 so that adjacent ones are separated from each other by a predetermined distance.

Each third inspection wiring 23c has the same length as the first inspection wiring 23a-1 in the second direction B. In addition, third electrode pads 25c are provided at both ends of each third inspection wiring 23c. The third electrode pads 25c are formed of the same material as the first electrode pads 25a and have the same shape and size.

A plurality of fourth inspection wirings 23d (23d-1, 23d-2, 23d-3, and 23d-4) are provided along the dicing street 13-2 in a manner separated from the plurality of third inspection wirings 23c by a predetermined distance along the second direction B. The plurality of fourth inspection wirings 23d are arranged in a direction orthogonal to the dicing street 13-2 in a manner that adjacent ones are separated from each other by a predetermined distance.

Each of the fourth inspection wirings 23d has the same length as the second inspection wiring 23b-1 in the second direction B. In addition, fourth electrode pads 25d are provided at both ends of each of the fourth inspection wirings 23d. The fourth electrode pads 25d are formed of the same material as the second electrode pads 25b and have the same shape and size.

In order to densely arrange the third inspection wiring 23c and the fourth inspection wiring 23d, the third electrode pad 25c and the fourth electrode pad 25d adjacent to each other in the second direction B are separated by the same distance as the distance between the first electrode pad 25a and the second electrode pad 25b adjacent to each other in the second direction B. In addition, the plurality of third inspection wirings 23c and the plurality of fourth inspection wirings 23d are alternately arranged along the dicing street 13-2.

In the second embodiment, since a plurality of inspection wirings 23 are provided on the dicing street 13-2 of the inspection substrate 11, it is possible to quantitatively evaluate the extent of the influence of the leakage light D on the dicing street 13-2. Furthermore, based on the number of the third inspection wirings 23c and the fourth inspection wirings 23d that have been disconnected, the frequency of the leakage light D reaching the third inspection wirings 23c and the fourth inspection wirings 23d can be calculated.

In addition, the configuration of the third inspection wiring 23c and the fourth inspection wiring 23d is not limited to the above example. The third inspection wiring 23c and the fourth inspection wiring 23d can also be arranged in a manner of being connected in a line along the second direction B through the third electrode pad 25c and the fourth electrode pad 25d. In addition, the third electrode pad 25c and the fourth electrode pad 25d can be arranged in addition to being arranged in the cutting street 13-2, and can also be arranged in the cutting street 13-1.

Next, the inspection substrate 11 of the third embodiment will be described. Fig. 8 is a partial enlarged view of the device region 15A of the third embodiment. In the inspection region 15b of the third embodiment, a plurality of fifth inspection wirings 23e (corresponding to a variation of the plurality of first inspection wirings 23a) are provided on the dicing street 13-2 side.

Each of the plurality of fifth inspection wirings 23e (23e-1, 23e-2, 23e-3, 23e-4 and 23e-5) has a length substantially equal to one side of the inspection region 15b along the second direction B. Both ends of each fifth inspection wiring 23e in the second direction B are aligned.

A fifth electrode pad 25e is provided at each of the two ends in the longitudinal direction of the fifth inspection wiring 23e. In addition, one or more fifth electrode pads 25e are further provided at predetermined intervals between the two ends of each fifth inspection wiring 23e.

In each fifth inspection wiring 23e, a plurality of fifth electrode pads 25e adjacent to each other in the first direction A are arranged in a row in the first direction A. That is, a plurality of fifth electrode pads 25e adjacent to each other in the first direction A are arranged at the same position in the second direction B.

In the inspection substrate 11 of the third embodiment, the first probe is brought into contact with one of a pair of fifth electrode pads 25e adjacent to each other in the second direction B in the fifth inspection wiring 23e, and the second probe is brought into contact with the other to perform a continuity test.

This makes it possible to check whether a portion of the fifth inspection wiring 23e between any pair of fifth electrode pads 25e adjacent to each other in the second direction B is disconnected. In addition, the frequency of the leakage light D reaching the fifth inspection wiring 23e can be calculated based on the number of disconnected regions.

The inspection wiring 23 of the third embodiment has the same length in the second direction B regardless of the distance from the dicing street 13-2. Therefore, for example, the leakage light D that reaches between the first inspection wiring 23a-5 and the second inspection wiring 23b-5 that are adjacent in the second direction B in the first embodiment will also reach the fifth inspection wiring 53e-5 in the third embodiment. Therefore, the frequency of the leakage light D can be calculated more accurately than in the first embodiment.

In addition, in the third embodiment, a plurality of fifth inspection wirings 23e are similarly provided across the four sides of one inspection area 15b. That is, the fifth inspection wirings 23e are provided near the dicing street 13-2 located on the opposite side to the dicing street 13-2 in the first direction A, and near the dicing street 13-1 located on one side (e.g., the positive direction side) and the other side (e.g., the negative direction side) of the second direction B.

Therefore, the frequency of the arrival of the leakage light D can be calculated based on the number of areas of the disconnected fifth inspection wiring 23e in each of the four sides of an inspection area 15b. In addition, the third embodiment can also quantitatively evaluate the distance from the cutting street 13 to which the influence of the leakage light D extends in each of the four sides of an inspection area 15b.

In addition, the structure and method of the above-mentioned embodiment can be appropriately changed and implemented within the scope of the purpose of the present invention. For example, the configuration of the inspection wiring 23 and the shape and configuration of the electrode pad 25 are not limited to the above-mentioned examples. The third inspection wiring 23c and the fourth inspection wiring 23d of the second embodiment can also be applied to the cutting street 13 of the inspection substrate 11 of the third embodiment.

In the above-mentioned embodiment, the disconnection of the inspection wiring 23 is determined by determining whether a measurable current flows between the first detector and the second detector within a predetermined measurement range. However, it is also possible to determine whether the inspection wiring 23 is partially damaged or whether the inspection wiring 23 is disconnected by measuring the change in the impedance value of the inspection wiring 23.

1: Frame unit 10: Laser processing device 11: Inspection substrate 11a: Front (surface on the other side) 11b: Back (surface on one side) 11c: Notch 11d: Modified layer 11e: Crack 12: Chuck table 12a: Holding surface 13,13-1,13-2: Cutting path 14: Clamp unit 15a: Component 15b: Inspection area 15A: Component area 15: Peripheral remaining area 16: Processing head 17: Cutting film 19: Ring frame Frame 23: Inspection wiring 23a: 1st inspection wiring 23b: 2nd inspection wiring 23c: 3rd inspection wiring 23d: 4th inspection wiring 23e: 5th inspection wiring 25: Electrode pad 25a: 1st electrode pad 25b: 2nd electrode pad 25c: 3rd electrode pad 25d: 4th electrode pad 25e: 5th electrode pad 27: Deteriorated area A: 1st direction B: 2nd direction C: Area D: Light leakage E: Moving direction L: Laser beam

FIG. 1 is a three-dimensional view of a frame unit. FIG. 2 is a top view showing a partial enlargement of a component area of the first embodiment. FIG. 3 is a partial cross-sectional side view of a frame unit and a laser processing device. FIG. 4 is an enlarged view of area C of FIG. 3. FIG. 5 (A) is a top view showing a partial enlargement of a component area; FIG. 5 (B) is a top view showing a partial enlargement of a component area. FIG. 6 is a flow chart showing an inspection method. FIG. 7 is a partial enlarged view of a component area of the second embodiment. FIG. 8 is a partial enlarged view of a component area of the third embodiment.

13-1,13-2: Cutting Road

15A: Component area

15a: Components

15b: Inspection area

23: Inspection wiring

23a-1, 23a-2, 23a-3, 23a-4, 23a-5: Wiring for the first inspection

23b-1, 23b-2, 23b-3, 23b-4, 23b-5: Wiring for the second inspection

25:Electrode pad

25a: 1st electrode pad

25b: Second electrode pad

A: Direction 1

B: Direction 2

Claims (3)

A test substrate for testing light leakage of a laser beam, characterized in that the test substrate comprises: a surface on one side, irradiated with the laser beam having a wavelength penetrating the test substrate; a surface on the other side, opposite to the surface on the one side; a cutting path, set on the surface on the other side; a plurality of first test wirings, each along the cutting path and arranged at different distances from the cutting path on the surface on the other side, and broken by the light leakage of the laser beam of predetermined energy; and a plurality of first electrode pads, two or more of which are set on each of the plurality of first test wirings on the surface on the other side, and separately arranged in the direction along the cutting path in each of the plurality of first test wirings. The inspection substrate as described in claim 1 further comprises a plurality of second inspection wirings which are separated from the plurality of first inspection wirings along the cutting path on the surface of the other side, and each of which is arranged at a different distance from the cutting path along the cutting path. A testing method for testing the light leakage of a laser beam using a testing substrate, wherein the testing substrate comprises: a surface on one side, which is irradiated with the laser beam having a wavelength that penetrates the testing substrate; a surface on the other side, which is opposite to the surface on the one side; a cutting path, which is set on the surface on the other side; a plurality of first testing wirings, each of which is arranged along the cutting path and at a different distance from the cutting path on the surface on the other side and is broken by the light leakage of the laser beam of predetermined energy; and a plurality of first electrode pads, which are arranged on the surface on the other side at least two on each of the plurality of first testing wirings, and are Each of the plurality of first inspection wirings is separately arranged in the direction along the cutting path; the inspection method comprises: a holding step, holding the surface side of the other side of the inspection substrate with a chuck table; a laser processing step, irradiating the laser beam along the cutting path from the surface side of the one side of the inspection substrate, and forming a modified layer along the cutting path inside the inspection substrate; and a light leakage confirmation step, after the laser processing step, making the detector contact the plurality of first electrode pads provided on each of the plurality of first inspection wirings, and confirming the presence or absence of the light leakage by confirming the disconnection of the plurality of first inspection wirings.