TWI872259B - Chip manufacturing method - Google Patents

Abstract

[Topic] When a wafer is divided by a method using a modified layer formed by a laser beam as a dividing starting point, the wafer is prevented from being divided outside the cutting path and the reduction in the bending strength of the obtained chip is prevented. [Solution] When a wafer is divided by a method using a modified layer formed by a laser beam as a dividing starting point to form a chip, not all functional layers existing in a plurality of cutting paths defining the boundaries of the chip are divided, but only a region of the functional layer that is roughly a cross (that is, a shape in which a rectangle extending in a specific direction and a rectangle extending in a direction orthogonal to the specific direction are arranged so that the centers of the two overlap) containing the intersection positions of the plurality of cutting paths is divided.

Description

Chip manufacturing method

The present invention relates to a method for manufacturing a chip by dividing a wafer to form a chip.

A chip with semiconductor elements is formed by dividing a wafer having a functional layer on the front side along a plurality of intersecting cutting paths. The functional layer is formed, for example, by doping an impurity region on the front side of a substrate made of semiconductors such as silicon with impurities and forming an insulating film and a conductive film on the impurity region. In addition, the plurality of cutting paths define the boundaries of the chip in the plane direction and are generally arranged in a grid shape.

Patent document 1 discloses a technology for dividing wafers using a laser beam, also known as SDBG (Stealth Dicing Before Grinding).

Specifically, in the invention described in Patent Document 1, after a laser beam is scanned on the front side of a wafer and a modified layer is formed on the substrate, the wafer is ground from the back side, whereby the modified layer becomes a starting point for division to divide the wafer. That is, in the invention described in Patent Document 1, a laser beam is used to form a modified layer on the cutting path that defines the boundary of the chip.

However, the thickness of the functional layer included in the chip has tended to increase due to the increasing demand for the quality of semiconductor devices in recent years (for example, the large capacity of semiconductor memories such as DRAM and NAND flash memory). Therefore, in the case where a modified layer is formed on the substrate as in the invention described in Patent Document 1, the portion where the modified layer is not formed tends to become thicker.

As a result, the functional layer of the wafer may not be separated along the cutting path. Specifically, there may be a problem that the crack formed on the modified layer of the substrate as the starting point of separation extends in a direction inclined relative to the vertical direction in the functional layer.

Patent document 2 discloses a method for solving this problem. Specifically, in the invention described in patent document 2, the cutting path is irradiated with laser light or scribing is performed in advance to form a groove deeper than the thickness of the functional layer, thereby allowing the crack with the modified layer as the starting point of the division to extend in the vertical direction.

[Learning Technology Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2004-111428.

[Patent Document 2] Japanese Patent Publication No. 2007-173475.

However, in the invention described in Patent Document 2, the groove formed in the cutting path penetrates the functional layer and reaches the substrate. Therefore, the substrate may be damaged and the bending strength of the chip may be reduced.

Therefore, the purpose of the present invention is to provide a chip manufacturing method, which can prevent the wafer from being divided outside the cutting path and prevent the reduction of the bending strength of the obtained chip when dividing the wafer by using the modified layer formed by the laser beam as the starting point of division.

According to the present invention, a chip manufacturing method is provided, wherein a wafer is divided along a plurality of cutting paths to form the chips, wherein the wafer has a functional layer formed on the front side of a substrate, and components are formed in a plurality of regions divided by the plurality of cutting paths arranged in a grid shape, and the chip manufacturing method comprises the following steps: a functional layer division step, wherein only the functional layer formed on the front side of the wafer and the plurality of cutting paths are divided; The functional layer is cut into a substantially cross-shaped area at the intersection of the cutting paths; a modified layer forming step, which irradiates a laser beam of a wavelength that penetrates the substrate of the wafer from the back side of the wafer along the multiple cutting paths to form a modified layer on the substrate; and a splitting step, which applies an external force to the wafer after the functional layer splitting step and the modified layer forming step to split the wafer into individual chips along the multiple cutting paths.

Preferably, the functional layer segmentation step is to irradiate the plurality of cutting paths formed on the wafer with a laser beam of a wavelength absorbed by the wafer from the front side of the wafer, thereby forming a laser-processed groove deeper than the thickness of the functional layer.

Preferably, the functional layer segmentation step is to perform scribing on the multiple cutting paths formed on the wafer to form scribing grooves deeper than the thickness of the functional layer.

Preferably, the dividing step is a back side grinding step, wherein the back side grinding step is to grind the wafer from the back side of the wafer by a grinding unit, thin it to the finished thickness of the chip, and divide the wafer into individual chips.

In the present invention, before the wafer is divided and the chips are formed by using the modified layer formed by the laser beam as the starting point for division, a part of the functional layer existing in the multiple cutting lanes is divided. Therefore, the possibility of the cracks using the modified layer as the starting point for division to progress in the area where the functional layer of the multiple cutting lanes has been divided is increased. In this way, the possibility of the wafer being divided outside the multiple cutting lanes can be reduced.

Furthermore, in the present invention, the residual portion of the functional layer existing in the plurality of cutting paths is not divided, so the substrate located thereunder will not be damaged. This can suppress the reduction in the bending strength of the resulting chip.

11: Wafer

13: Back

15: Substrate

17: Front

19: Functional layer

21: Cutting Road

23: Region (semiconductor components)

25: Laser processing groove

27: Modified layer

10: Chuck table

12: Laser processing unit

14: Camera unit

16: Framework

18: Adhesive film

20: Chuck table

22: Laser irradiation unit

26: Adhesive film

28: Chuck table

30: Grinding unit

32: Axis

34: Axis

36: Grinding stone

38: Expanding film

40: Drum wheel

42: Support unit

44: Support platform

46: Clamp

48: Rod

50:Framework

Figure 1 is a three-dimensional diagram showing an example of a wafer.

Figure 2 is a three-dimensional diagram showing an example of the functional layer segmentation step.

Figure 3 is a partially enlarged top view of an example of a wafer after the functional layer separation step.

FIG4 is a longitudinal cross-sectional view showing an example of a modified layer forming step.

Figure 5 is a three-dimensional diagram showing an example of the segmentation step.

FIG6 is a longitudinal cross-sectional view showing another example of the segmentation step.

FIG7 is a longitudinal cross-sectional view showing another example of the segmentation step.

In the present invention, when a wafer is divided and a chip is formed by using a modified layer formed by a laser beam as a dividing starting point, the functional layer existing in the multiple cutting paths defining the boundaries of the chip is not completely divided, but only the area of the functional layer that includes the intersection position of the multiple cutting paths (that is, in a top view, a rectangle extending in a specific direction and a rectangle extending in a direction orthogonal to the specific direction are arranged in a manner that the center portions of the two overlap) is divided.

An example of this invention is described in detail below with reference to Figures 1 to 5. In addition, the chip manufacturing method described below is only an implementation method of the present invention, and it goes without saying that the present invention is not limited to the invention described below.

FIG. 1 is a diagram showing an example of a wafer used for manufacturing a chip. The wafer 11 shown in FIG. 1 has a substrate 15 having a substantially disk shape, and the substrate 15 is obtained by forming a notch or an orientation plane for indicating the crystal direction on a thin substrate, and the thin substrate is cut from a cylindrical crystal rod composed of a semiconductor such as silicon. Then, a functional layer 19 is formed on the front surface of the substrate 15, and the functional layer 19 includes an impurity region doped with impurities and a plurality of insulating films and a plurality of conductive films formed on the impurity region.

In addition, in this specification, for convenience, the side of the wafer 11 where the substrate 15 exists is called the back side 13, and the side where the functional layer 19 exists is called the front side 17.

In the functional layer 19, multiple regions are divided by multiple cutting lines 21 arranged in a grid shape. The functional layers 19 located in multiple regions 23 constitute independent semiconductor elements, and a chip with semiconductor elements is manufactured by dividing the wafer 11 along the multiple cutting lines 21.

In addition, various wafers can be used as the wafer 11. For example, a wafer having a size of 8 to 12 inches and a thickness of 725 to 775 μm can be used as the wafer 11.

In addition, although the present specification describes the processing of a disk-shaped wafer 11 made of semiconductors such as silicon, there is no restriction on the material, shape, structure, and size of the wafer to be processed. For example, the processing disclosed in this specification can be performed on wafers of any shape formed using other semiconductors, ceramics, resins, and metals. Similarly, there is no restriction on the type, quantity, shape, structure, size, and configuration of the components formed on the wafer.

FIG. 2 is a three-dimensional diagram showing an example of a functional layer segmentation step for segmenting a portion of the functional layer 19 existing in the plurality of cutting paths 21 shown in FIG. 1 .

The functional layer segmentation step shown in FIG2 is performed using a laser processing device having a chuck table 10, a laser processing unit 12, and a camera unit 14.

The chuck table 10 has a substantially horizontal holding surface for holding the workpiece. In addition, the chuck table 10 can move in the X arrow direction and the Y arrow direction shown in FIG. 2 by a moving mechanism not shown in the figure while holding the workpiece on the holding surface. In addition, both arrow directions are directions substantially parallel to the holding surface, and both arrow directions are directions substantially orthogonal to each other.

The laser processing unit 12 is arranged above the chuck table 10 and can irradiate the holding surface of the chuck table 10 with a pulsed laser beam of a wavelength (e.g., 355 nm) absorbed by the wafer 11. The pulsed laser beam is absorbed by at least one of the substrate 15 and the functional layer 19.

The camera unit 14 is installed above the chuck table 10 at the same time as the laser processing unit 12, and can take pictures of the holding surface of the chuck table 10.

In the functional layer separation step, first, the annular frame 16 is adhered to the peripheral area of the upper surface of the disc-shaped adhesive film 18, and the back side of the wafer 11 is adhered to the central area. Then, the back side of the wafer 11 is set on the holding surface of the chuck table 10.

Next, the imaging unit 14 detects the position information of the plurality of cutting paths 21 formed on the wafer 11. Next, the chuck table 10 is moved in such a manner that the laser beam irradiated from the laser processing unit 12 scans along the plurality of cutting paths 21 according to the position information of the plurality of cutting paths 21 detected.

Specifically, first, the chuck table 10 is moved in a manner of irradiating a laser beam along any one of the plurality of cutting paths 21, wherein the plurality of cutting paths 21 are arranged in a grid-like manner and are arranged in parallel along a first direction. At this time, the laser processing unit 12 irradiates a pulsed laser beam only in the vicinity of the intersection position of the plurality of cutting paths 21 along the first direction.

The laser beam is a laser beam of a wavelength absorbed by the wafer 11. Therefore, laser ablation occurs in the area irradiated by the laser beam to form a groove.

By repeatedly irradiating this laser beam, rectangular laser processing grooves separated from each other and with their long sides along the first direction are formed at the intersection of the cutting road in a top view. In addition, the remaining cutting roads 21 arranged parallel to the first direction like the cutting road 21 are also irradiated with laser beams in sequence.

Next, after the chuck table 10 is rotated 90°, the multiple cutting paths 21 arranged in a grid pattern and arranged orthogonally to the multiple cutting paths 21 with laser processing grooves formed thereon are also sequentially irradiated with laser beams. In other words, the multiple cutting paths 21 arranged parallel to the second direction substantially orthogonal to the first direction are also sequentially irradiated with laser beams.

As a result, as shown in FIG3 , a plurality of laser-processed grooves 25 are formed only in the substantially cross-shaped region including the intersection positions of the plurality of cutting paths 21 dividing the plurality of regions 23. In addition, the laser-processed grooves 25 are deeper than the thickness of the functional layer 19 existing in the plurality of cutting paths 21. That is, the laser-processed grooves 25 penetrate the functional layer 19 in a manner in which the bottom surface thereof is located on the substrate 15.

Therefore, the substrate 15 is exposed at the bottom surface of the laser-processed groove 25. In addition, the functional layer 19 is divided in the area where the laser-processed groove 25 has been formed in the plurality of cutting paths 21.

Furthermore, the plurality of laser-processed grooves 25 are respectively far away from each other and are located in a region that includes any one of the plurality of intersection positions and does not include any intersection positions other than the intersection position.

In addition, various laser processing units 12 can be used. For example, laser processing units 12 can be used with YAG laser oscillators, YVO4 laser oscillators, and CO2 laser oscillators. In addition, laser processing units 12 can be used with a wavelength of 266 to 10600 nm, an average output of 0.1 to 50.0 W, and a pulse repetition frequency of 10 kHz to 50 MHz.

In addition, TEG (Test Element Group) used to evaluate the performance of semiconductor components is generally set on multiple cutting lanes 21 from the perspective of effectively utilizing the wafer 11. On the other hand, if TEG remains on multiple cutting lanes 21, it will become difficult to separate the wafer 11 along the multiple cutting lanes 21 in the subsequent separation step.

Therefore, this type of TEG is preferably formed in a substantially cross-shaped area including the intersection positions of multiple cutting paths 21, and is removed by forming a laser-processed groove 25 in the functional layer segmentation step.

In other words, the laser processed groove 25 is preferably a size that can completely remove such TEG. For example, the laser processed groove 25 is preferably a shape larger than the following: in a top view, two rectangles are arranged in a central overlapping manner, the two rectangles are: a rectangle with a long side of 50μm, the long side extending along the direction of one of the two roughly orthogonal cutting paths; and a rectangle with a long side of 50μm, the long side extending along the direction of the other of the two cutting paths.

On the other hand, from the viewpoint of suppressing the reduction in the bending strength of each chip obtained by dividing the wafer 11, it is preferable that the size of the laser processed groove 25 is small. For example, in a portion of the laser processed groove 25 located between a pair of regions 23 adjacent to each other through a specific cutting path, the length in the direction in which the cutting path extends (for example, "L1" shown in FIG. 3) is preferably 1/4 of the length of the region 23 in the direction (for example, "L2" shown in FIG. 3), more preferably less than 1/8, and most preferably less than 1/12.

The functional layer segmentation step in the implementation method of the present invention is implemented as described above.

FIG4 is a longitudinal cross-sectional view showing an example of a modified layer forming step performed after the functional layer segmentation step. The modified layer forming step shown in FIG4 is performed using a laser irradiation device having a chuck table 20 and a laser irradiation unit 22.

The chuck table 20 has a substantially horizontal holding surface for holding the workpiece. In addition, the chuck table 20 can move in the direction of the arrow X shown in FIG. 4 by a moving mechanism not shown in the figure while holding the workpiece on the holding surface. In addition, the direction is a direction substantially parallel to the holding surface.

The laser irradiation unit 22 is arranged above the chuck table 20 and can irradiate the holding surface side of the chuck table 20 with a laser beam.

In the modified layer forming step, first, the front surface 17 of the wafer 11 is adhered to the upper surface of a disc-shaped adhesive film 26 having a diameter substantially the same as that of the wafer 11. Then, in the functional layer separation step, the adhesive film 18 adhered to the back surface 13 of the wafer 11 is removed (see FIG. 2).

Next, the front side 17 of the wafer 11 is placed on the holding surface of the chuck table 20 through the adhesive film 26. Next, the laser irradiation unit 22 is set so that the focal point of the pulse laser beam of a wavelength (e.g., 1064 nm) that penetrates the substrate 15 is located inside the substrate 15.

Next, the chuck table 20 is moved so that the laser beam emitted from the laser irradiation unit 22 scans along the plurality of cutting paths 21, and a pulsed laser beam of a wavelength that penetrates the substrate 15 of the wafer 11 is emitted from the laser irradiation unit 22.

Specifically, first, the laser beam is sequentially irradiated on the plurality of cutting paths 21 arranged in parallel along the first direction among the plurality of cutting paths 21 arranged in a grid shape.

Next, after the chuck table 20 is rotated 90°, the multiple cutting paths 21 arranged in a grid pattern and arranged orthogonally to the multiple cutting paths 21 already irradiated with the laser beam are also sequentially irradiated with the laser beam. In other words, the multiple cutting paths 21 arranged parallel to the second direction substantially orthogonal to the first direction are also sequentially irradiated with the laser beam.

As a result, as shown in FIG. 4 , a modified layer 27 is formed in the substrate 15 existing in the plurality of cutting paths 21 (specifically, the region overlapping with the plurality of laser-processed grooves 25 separated from each other, and the region overlapping with the functional layer 19 located between the adjacent laser-processed grooves 25).

In addition, various laser irradiation units 22 can be used. For example, laser irradiation units 22 can be used with YAG laser oscillators and YVO4 laser oscillators. In addition, laser irradiation units 22 can have a wavelength of 1099 to 1400 nm, an average output of 0.5 to 3.0 W, and a pulse repetition frequency of 80 to 150 kHz.

The modified layer forming step in the embodiment of the present invention is implemented as described above.

FIG5 is a perspective view showing an example of a splitting step performed after the modified layer forming step. The splitting step shown in FIG5 is performed using a grinding device having a chuck table 28 and a grinding unit 30.

The chuck table 28 has a substantially horizontal holding surface for holding the workpiece. In addition, the chuck table 28 can rotate around the axis 32 by a rotating mechanism (not shown) while holding the workpiece on the holding surface.

The grinding unit 30 is arranged above the chuck table 28 and rotates around the axis 34 by a rotating mechanism (not shown) and can grind the workpiece placed on the holding surface of the chuck table 28 by the grinding stone 36.

In the splitting step, first, the front side of the wafer 11 is placed on the holding surface of the chuck table 28 through the adhesive film 26.

Next, while the chuck table 28 and the grinding unit 30 are rotated together, the grinding unit 30 is lowered and the back side of the wafer 11 is brought into contact with the grinding stone 36, thereby grinding the wafer 11.

Thus, the wafer 11 is thinned to a predetermined finished thickness corresponding to the descending amount of the grinding unit 30, and an external force is applied to the wafer 11 by the grinding. As a result, the modified layer 27 existing in the substrate 15 of the wafer 11 becomes the starting point for division, and the wafer 11 is divided into individual chips along the multiple dicing streets 21.

The segmentation step in the embodiment of the present invention is implemented as described above. Thereby, a plurality of chips are formed.

In the above-mentioned chip manufacturing method, before the wafer 11 is divided and the chip is formed by using the modified layer 27 formed by the laser beam as the dividing starting point, a part of the functional layer 19 existing in the multiple cutting lanes 21 is divided. Therefore, the possibility of the crack using the modified layer 27 as the dividing starting point to progress in the area where the functional layer 19 of the multiple cutting lanes 21 has been divided increases. Thereby, the possibility of the wafer 11 being divided outside the multiple cutting lanes 21 can be reduced.

Furthermore, in the above-mentioned chip manufacturing method, since the remaining portion of the functional layer 19 existing in the plurality of cutting paths 21 is not divided, the substrate 15 located thereunder will not be damaged. This can suppress the reduction in the bending strength of the obtained chip.

The above-mentioned chip manufacturing method is one aspect of the present invention, and a chip manufacturing method using steps different from the above-mentioned method is also included in the present invention. For example, at least one of the steps in the above-mentioned chip manufacturing method can also be replaced by the steps described later.

First, in the above-mentioned chip manufacturing method, although an example of performing the modified layer forming step after the functional layer segmentation step is shown, the order of the two steps is not particularly limited, and the functional layer segmentation step may also be performed after the modified layer forming step.

Furthermore, in the above-mentioned chip manufacturing method, as the functional layer separation step in the present invention, although the step of forming the laser processing groove 25 in the state where the wafer 11 is adhered to the adhesive film 18 is shown, the functional layer separation step in the present invention can also be performed in the state where the wafer 11 is not adhered to the adhesive film 18.

In the case where the functional layer separation step is performed when the wafer 11 is not adhered to the adhesive film 18, it is preferred because it is not necessary to remove the adhesive film 18 from the wafer 11. On the other hand, in the case where the functional layer separation step is performed when the wafer 11 is adhered to the adhesive film 18, it is preferred because the frame 16 is adhered to the adhesive film 18, which can improve the convenience (handling) when the wafer 11 is set on the holding surface of the chuck table 10 and when the wafer 11 is removed from the holding surface of the chuck table 10.

Furthermore, in the above-mentioned chip manufacturing method, as the functional layer segmentation step in the present invention, although a step of irradiating a plurality of cutting paths 21 with a laser beam to form a laser-processed groove 25 deeper than the thickness of the functional layer 19 is shown (refer to FIGS. 2 and 3), the functional layer segmentation step in the present invention is not limited to the use of a laser beam.

For example, as the functional layer segmentation step in the present invention, a step of performing scribing processing on a plurality of cutting paths 21 to form scribing processing grooves deeper than the thickness of the functional layer 19 can also be adopted. The scribing processing can be performed, for example, using a diamond scribing tool.

Furthermore, in the above-mentioned chip manufacturing method, as the dividing step in the present invention, although a back grinding step of grinding the back side of the wafer 11 by a grinding device to divide the wafer 11 into individual chips is shown (refer to FIG. 5 ), the dividing step in the present invention is not limited to the use of a grinding device.

For example, as a separation step of the present invention, the step of separating the wafer 11 by expanding the expansion film 38 shown in Figures 6 and 7 can be adopted. Specifically, the step shown in Figure 6 is performed using an expansion device having a cylindrical drum 40 and a support unit 42.

The support unit 42 has a ring-shaped support platform 44 arranged to surround the upper end of the drum 40. The support platform 44 can support the peripheral area of the expanded object.

In addition, the support unit 42 has a plurality of clamps 46 arranged at approximately equal intervals along the circumference of the support platform 44. The plurality of clamps 46 can hold and fix the peripheral area of the expanded object together with the support platform 44.

Furthermore, the support unit 42 has a plurality of rods 48 arranged at approximately equal intervals along the circumference of the support platform 44. The plurality of rods 48 support the support platform 44 and the plurality of clamps 46, and can be raised and lowered together with the support platform 44 and the plurality of clamps 46 by a lifting mechanism not shown.

In the splitting step, first, a ring-shaped frame 50 is adhered to the peripheral area of the upper surface of the disc-shaped expansion film 38, and then the back surface 13 of the wafer 11 is adhered to the central area. Then, in the modified layer forming step, the adhesive film 26 adhered to the front surface 17 of the wafer 11 is removed (see Figure 4).

Next, the plurality of rods 48 are raised and lowered in such a manner that the upper surface of the support platform 44 is located on the same plane as the upper end of the drum 40. Next, as shown in FIG6 , the peripheral area of the expansion film 38 and the frame 50 are fixed by the clamp 46 in such a manner that the back surface 13 of the wafer 11 faces downward. Next, as shown in FIG7 , the plurality of rods 48 are lowered together with the support platform 44 and the plurality of clamps 46.

Thus, the central area of the expansion film 38 is expanded toward the plane direction of the wafer 11 only by the distance between the upper end of the drum 40 and the support platform 44. At this time, the force of expansion toward the plane direction acts on the wafer 11 adhered to the expansion film 38. As a result, the modified layer 27 in the substrate 15 of the wafer 11 becomes the starting point for division, and the wafer 11 is divided into individual chips along the multiple cutting paths 21.

(Implementation example)

The following is an example of the present invention. First, a wafer having a functional layer and a thickness of about 700 μm is prepared on the front side of a substrate made of 12-inch silicon. The wafer is divided by a plurality of dicing lanes arranged in a grid pattern so that the size of the final chip is 12.73 mm × 12.44 mm.

Next, prepare sample 1 and sample 2. Sample 1 is a sample in which a plurality of laser-processed grooves are formed by irradiating the front side of the wafer with a laser beam having an average output of 1.1W, and sample 2 is a sample in which a plurality of laser-processed grooves are formed by irradiating the front side of the wafer with a laser beam having an average output of 2.0W (functional layer segmentation step).

The multiple laser-processed grooves in samples 1 and 2 are respectively formed only in the roughly cross-shaped area including the intersection positions of multiple cutting paths, and penetrate the functional layer in a manner in which the bottom surface is located on the substrate.

In addition, the multiple laser processed grooves in samples 1 and 2 are respectively arranged in a shape of two rectangles overlapped at the center when viewed from above. The two rectangles are: a rectangle with a long side of 1.5 mm, whose long side extends along the direction of one of the two roughly orthogonal cutting paths; and a rectangle with a long side of 1.5 mm, whose long side extends along the direction of the other of the two cutting paths.

In addition, the laser beam used to prepare samples 1 and 2 is a pulsed laser beam with a wavelength of 355nm and a pulse repetition frequency of 600kHz.

Furthermore, in the functional layer separation step, the chuck table holding the wafer is moved at a feed speed of 250 mm/s while the wafer is irradiated with a laser beam.

Furthermore, in the functional layer segmentation step, first, the laser beam is sequentially irradiated on the multiple cutting paths arranged in parallel among the multiple cutting paths arranged in a grid pattern, and then, after the chuck table is rotated 90°, the laser beam is sequentially irradiated on the multiple cutting paths arranged orthogonally to the cutting paths.

Next, laser beams are irradiated on multiple cutting paths from the back side of samples 1 and 2 respectively to form a modified layer on the substrate (modified layer formation step).

In addition, the laser beam irradiated to samples 1 and 2 in the modified layer formation step is a pulse laser beam with a wavelength of 1099nm and a pulse repetition frequency of 120kHz. The focal point of the pulse laser beam is set at two locations with different heights in the substrate. In addition, the average output of the laser beam with the two locations as the focal point is 1.5W.

Furthermore, in the modified layer formation step, the chuck table holding each sample is moved at a feed speed of 1000 mm/s while irradiating each sample with a laser beam.

Furthermore, in the step of forming the modified layer, the laser beam is first irradiated sequentially on the multiple cutting paths arranged in parallel among the multiple cutting paths arranged in a grid pattern, and then, after the chuck table is rotated 90°, the laser beam is irradiated sequentially on the multiple cutting paths arranged orthogonally to the cutting paths.

Finally, the back of each sample is ground and thinned to a predetermined thickness, and then separated along multiple cutting paths to produce individual chips (splitting step). At this time, both samples are separated along multiple cutting paths, and there will be no problem of cracks extending in a direction inclined relative to the vertical direction with the modified layer as the starting point of the separation.

As a comparative example for comparison with the chips obtained from samples 1 and 2 of the above-mentioned embodiment, the sample described below was prepared. First, individual chips were manufactured by the same method as the embodiment except that the above-mentioned functional layer segmentation step was not performed (Comparative Example 1).

Furthermore, in the above-mentioned functional layer segmentation step, except that a plurality of laser-processed grooves deeper than the thickness of the functional layer are formed in the entirety of the plurality of cutting paths, individual chips are manufactured by the same method as in the embodiment (Comparative Example 2).

The flexural strength test of the chips manufactured in the embodiment and comparative examples 1 and 2 was conducted. Specifically, the chip was supported in a manner such that the distance between the fulcrums was 3 mm, and the rod in contact with the chip between the fulcrums was moved at a feed rate of 1 mm/min, thereby obtaining the flexural strength of each chip.

The flexural strength of each chip obtained through the above flexural strength test is as shown in Table 1.

As shown in Table 1, the bending strength of Comparative Example 2, in which a laser-processed groove deeper than the thickness of the functional layer is formed in the overall multi-cutting path in the functional layer segmentation step, is greatly reduced, while the chip manufactured by the embodiment does not have this situation and has the same bending strength as Comparative Example 1, in which the functional layer segmentation step is not performed.

15: Substrate

21: Cutting Road

23: Region (semiconductor components)

25: Laser processing groove

L1: The length of a portion of the laser-processed groove in the direction in which the cutting path extends

L2: Length of the region

Claims (4)

A method for manufacturing a chip, wherein a wafer is divided along a plurality of cutting paths to form a chip, wherein a functional layer is formed on the front side of a substrate, and components are formed in a plurality of regions divided by the plurality of cutting paths arranged in a grid pattern, and the method for manufacturing the chip comprises the following steps: A functional layer division step, wherein only a substantially cross region including the intersection position of the plurality of cutting paths in the functional layer formed on the front side of the wafer is divided; A modified layer formation step, wherein a laser beam of a wavelength penetrating the substrate of the wafer is irradiated from the back side of the wafer along the plurality of cutting paths to form a modified layer on the substrate; and The dividing step, after the functional layer dividing step and the modified layer forming step, applies external force to the wafer to divide the wafer into individual chips along the multiple cutting paths. A method for manufacturing a chip as claimed in claim 1, wherein the functional layer separation step is to irradiate the multiple cutting paths formed on the wafer with a laser beam of a wavelength absorbed by the wafer from the front side of the wafer, thereby forming a laser-processed groove deeper than the thickness of the functional layer. A method for manufacturing a chip as claimed in claim 1, wherein the functional layer separation step is to perform scribing processing on the multiple cutting streets formed on the wafer to form scribing processing grooves that are deeper than the thickness of the functional layer. A method for manufacturing a chip as claimed in any one of claims 1 to 3, wherein the dividing step is a back side grinding step, wherein the back side grinding step is performed by grinding the wafer from the back side of the wafer by a grinding unit, thinning the wafer to a finished thickness of the chip, and dividing the wafer into individual chips.