CN117334569A - Method for manufacturing chip - Google Patents

Abstract

The invention provides a method for manufacturing chips, which can reliably divide a wafer with a film and can improve the productivity. A method for manufacturing a chip, which is to divide a wafer having a film formed on the back surface along a line to divide, and manufacture the chip, the method comprising the steps of: a laser beam irradiation step of irradiating a laser beam along a dividing line set in the wafer, forming a burn mark on a film formed on the back surface, and forming a modified region in the wafer; and a dividing step of applying an external force to the wafer after the laser beam irradiation step is performed, and dividing the wafer along the ablation mark formed by the laser beam irradiation step.

Description

Chip manufacturing method

Technical field

The present invention relates to a method of manufacturing a chip.

Background technique

An optical device wafer with an optical device layer laminated on the front surface of a sapphire (Al ₂ O ₃ ) substrate, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, or a lithium tantalate (LiTaO ₃ ) substrate, or a niobate A lithium (LiNbO ₃ ) substrate, a silicon carbide (SiC) substrate, a diamond substrate, a SAW wafer with a SAW (surface elastic wave) device formed on the front surface of a quartz substrate, etc. are cut along a plurality of intersecting planned division lines to be divided into individual devices to manufacture chips.

As a method for dividing the above-mentioned wafer, there is known a laser processing method in which a pulsed laser beam with a wavelength that is transparent to the wafer is used, a focusing point is positioned inside the area to be divided, and the pulsed laser beam is irradiated. A modified layer is formed as a starting point for division, and external force is applied to cause division (for example, see Patent Document 1).

The method shown in the above-mentioned Patent Document 1 can also be applied to a wafer in which a metal film or a DBR (Distributed Bragg Reflector) film is laminated on the back surface of the wafer. When the wafer is processed, the wafer is modified. The cracks produced in the plasma layer also separate the laminated membranes.

However, in recent years, there has been a tendency for the film thickness to become thicker for the purpose of improving brightness, etc. This has led to the following problems: cracks are difficult to extend, resulting in segmentation failure or edge chipping.

Therefore, a method has been proposed in which the laminated film is removed using a cutting tool or etching, and then laser processing is performed (for example, see Patent Document 2).

Patent Document 1: Japanese Patent No. 3408805

Patent Document 2: Japanese Patent Application Publication No. 2016-164924

If the processing method shown in Patent Document 2 is used, the above-mentioned problems can be solved, but further improvement in productivity is required.

Contents of the invention

Therefore, an object of the present invention is to provide a chip manufacturing method that can reliably divide a wafer with a film and improve productivity.

According to the present invention, there is provided a chip manufacturing method for manufacturing a chip by dividing a wafer having a film formed on the front or back surface along a plurality of intersecting planned dividing lines, wherein the chip manufacturing method has the following steps: laser beam an irradiation step of irradiating a laser beam along the planned dividing line set on the wafer to form ablation marks on the film formed on the front or back surface, and forming a modified region inside the wafer; and a dividing step, After the laser beam irradiation step is performed, an external force is applied to the wafer, and the wafer is divided along the ablation marks formed by the laser beam irradiation step.

Preferably, in the laser beam irradiation step, a focusing area of a laser beam having a wavelength that is transparent to the wafer and absorptive to the film is positioned from the inside of the wafer to the front surface of the film or closer to the front surface. At the outer position, the laser beam is irradiated along the planned division line set on the wafer, thereby forming an ablation mark on the film simultaneously with forming a modified region inside the wafer.

Preferably, the laser beam irradiation step includes the following steps: a modified region forming step, in which a focused region of a laser beam with a wavelength that is transparent to the wafer is positioned inside the wafer to form a modified region; and an ablation mark. In the forming step, after the modified region forming step is performed, a focusing region of a laser beam with a wavelength that is absorptive for the film is positioned near the film to form an ablation mark.

Preferably, in the laser beam irradiation step, the modified region formed inside the wafer includes pores and amorphous matter surrounding the pores.

The present invention has the following effects: a wafer with a film can be reliably divided and productivity can be improved.

Description of drawings

FIG. 1 is a perspective view schematically showing a wafer to be processed by the chip manufacturing method according to the first embodiment.

FIG. 2 is a cross-sectional view schematically showing the wafer shown in FIG. 1 .

FIG. 3 is a flowchart showing the flow of the chip manufacturing method according to the first embodiment.

FIG. 4 is a perspective view schematically showing a laser beam irradiation step of the chip manufacturing method shown in FIG. 3 .

FIG. 5 is a cross-sectional view schematically showing a main part of the wafer irradiated with a laser beam in the laser beam irradiation step of the chip manufacturing method shown in FIG. 3 .

FIG. 6 is a cross-sectional view schematically showing another example of the main part of the wafer shown in FIG. 5 .

FIG. 7 is a perspective view schematically showing the main part of the wafer after the laser beam irradiation step of the chip manufacturing method shown in FIG. 3 .

8 is a cross-sectional view schematically showing the main part of the wafer after the laser beam irradiation step of the chip manufacturing method shown in FIG. 3 .

FIG. 9 is a perspective view schematically showing a modified region formed on the wafer shown in FIG. 8 .

FIG. 10 is a side view schematically showing, in partial cross-section, a state in which a wafer is held by a dividing device in the dividing step of the chip manufacturing method shown in FIG. 3 .

FIG. 11 is a side view schematically showing, in partial cross-section, a state in which a wafer is divided into chips by a dividing device in the dividing step of the chip manufacturing method shown in FIG. 3 .

FIG. 12 is a plan view schematically showing a chip divided in the dividing step of the chip manufacturing method shown in FIG. 3 .

FIG. 13 is a flowchart showing the flow of the chip manufacturing method according to the second embodiment.

14 is a cross-sectional view schematically showing a main part of the wafer irradiated with a laser beam in a modified region forming step of the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 .

FIG. 15 is a cross-sectional view schematically showing the main part of the wafer after the modified region forming step of the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 .

16 is a cross-sectional view schematically showing a main part of the wafer irradiated with a laser beam in the ablation mark forming step of the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 .

FIG. 17 is a cross-sectional view schematically showing the main part of the wafer after the ablation mark forming step in the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 .

Label description

1: Wafer; 3: Back surface; 4: Film; 5: Front surface; 6: 1st scheduled dividing line (scheduled dividing line); 7: 2nd scheduled dividing line (scheduled dividing line); 9: Front surface; 10: Chip; 11: Ablation marks; 12: Modified area; 12-2: Modified layer (modified area); 21: Laser beam; 101: Laser beam irradiation step; 101-1: Modified area formation step; 101-2 : Ablation mark formation step; 102: segmentation step; 121: pores; 122: amorphous; 211: light-condensing area; 211-2: light-condensing point (light-condensing area).

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the structural elements described below include those that are easily thought of by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined appropriately. In addition, various omissions, substitutions, or changes in the structure may be made without departing from the gist of the present invention.

[First Embodiment]

The chip manufacturing method according to the first embodiment of the present invention will be described based on the drawings. FIG. 1 is a perspective view schematically showing a wafer to be processed by the chip manufacturing method according to the first embodiment. FIG. 2 is a cross-sectional view schematically showing the wafer shown in FIG. 1 . FIG. 3 is a flowchart showing the flow of the chip manufacturing method according to the first embodiment.

The chip manufacturing method according to the first embodiment is the processing method of the wafer 1 shown in FIG. 1 . As shown in FIGS. 1 and 2 , a wafer 1 to be processed by the chip manufacturing method of the first embodiment has a metal film or a DBR (Distributed Bragg Reflector) with a uniform thickness formed on the back surface 3 of a substrate 2 A disc-shaped optical device wafer of the film 4 such as a reflector film or a wafer such as a SAW (Surface Acoustic Wave) wafer.

The optical device wafer is a wafer with an optical device layer laminated on the front surface of a sapphire (Al ₂ O ₃ ) substrate, a silicon carbide (SiC) substrate, or a gallium nitride (GaN) substrate. The SAW wafer is a wafer made of lithium tantalate (LiTaO ₃ ). A wafer with a SAW device is formed on the front surface of the substrate, the lithium niobate (LiNbO ₃ ) substrate, the silicon carbide (SiC) substrate, the diamond substrate, and the quartz substrate.

The wafer 1 has the device 8 formed on the front surface 5 of the substrate 2 in the area divided by the mutually parallel first planned division lines 6 and the mutually parallel second planned division lines 7 , and the film 4 is formed on the back surface 3 of the substrate 2 . In addition, in the first embodiment, the first planned dividing line 6 and the second planned dividing line 7 are perpendicular to each other.

In the first embodiment, the substrate 2 of the wafer 1 is made of C-plane sapphire, and the device 8 formed on the front surface 5 of the substrate 2 is an LED (Light-Emitting Diode) including an epitaxial film formed by GaN-based epitaxial film deposition. led). In addition, in the first embodiment, in order to increase the brightness, the wafer 1 is provided with a PSS (Patterned Sapphire Substrate: Patterned Sapphire Substrate) structure at the interface between the device 8 as an LED and the substrate 2 .

In addition, in the first embodiment, the film 4 formed on the back surface 3 of the substrate 2 of the wafer 1 is a DBR film (dielectric multilayer film). In addition, in the first embodiment, the outer diameter of the wafer 1 is 6 inches, the thickness is 150 μm, and the device 8 has a size of 200 μm×200 μm. The wafer 1 having the above structure is divided into chips 10 along the planned dividing lines 6 and 7 . In addition, the chip 10 has a part of the substrate 2 and parts of the device 8 and the film 4 .

The chip manufacturing method of the first embodiment is a method of dividing the wafer 1 having the film 4 formed on the back surface 3 of the substrate 2 along the planned dividing lines 6 and 7 to manufacture the chip 10 . As shown in FIG. 3 , the chip manufacturing method according to the first embodiment includes a laser beam irradiation step 101 and a dividing step 102 .

(Laser beam irradiation step)

FIG. 4 is a perspective view schematically showing a laser beam irradiation step of the chip manufacturing method shown in FIG. 3 . FIG. 5 is a cross-sectional view schematically showing a main part of the wafer irradiated with a laser beam in the laser beam irradiation step of the chip manufacturing method shown in FIG. 3 . FIG. 6 is a cross-sectional view schematically showing another example of the main part of the wafer shown in FIG. 5 . FIG. 7 is a perspective view schematically showing the main part of the wafer after the laser beam irradiation step of the chip manufacturing method shown in FIG. 3 . 8 is a cross-sectional view schematically showing the main part of the wafer after the laser beam irradiation step of the chip manufacturing method shown in FIG. 3 . FIG. 9 is a perspective view schematically showing a modified region formed on the wafer shown in FIG. 8 .

The laser beam irradiation step 101 is a step of irradiating the laser beam 21 along the planned dividing lines 6 and 7 set on the wafer 1 (as shown in FIGS. 4 , 5 and 6 ) to irradiate the film 4 formed on the back surface 3 Ablation marks 11 are formed (as shown in FIGS. 7 and 8 ), and modified regions 12 are formed inside the substrate 2 of the wafer 1 (as shown in FIGS. 7 , 8 and 9 ). In addition, in order to increase the brightness, the wafer 1 is provided with a PSS structure at the interface between the device 8 as an LED and the substrate 2. Therefore, the laser beam 21 is scattered and it is difficult to irradiate the laser beam 21 from the front surface 5 side.

In the laser beam irradiation step 101 , as shown in FIG. 4 , the laser processing device 20 attracts and holds the front surface 5 side of the wafer 1 to the holding surface 23 of the holding table 22 . In addition, in the first embodiment, the wafer 1 has a disk-shaped belt 13 (shown in FIG. 10 ) with a larger diameter than the wafer 1 attached to the front surface 5 side, and an annular frame 14 ( As shown in FIG. 10 ), the front side 5 is attracted and held on the holding surface 23 via the belt 13 . In addition, the belt 13 and the ring frame 14 are omitted in FIG. 4 .

In the first embodiment, in the laser beam irradiation step 101 , the laser processing apparatus 20 uses an infrared camera 24 or the like to photograph the back surface 3 of the wafer 1 held by suction and holding the holding table 22 , and performs the planned division lines 6 and 7 . Alignment of the laser beam irradiation unit 25 and the planned division lines 6 and 7 is performed based on detection or the like. In the first embodiment, in the laser beam irradiation step 101 , the laser processing apparatus 20 moves the laser beam irradiation unit 25 and the wafer 1 relatively along the planned dividing lines 6 and 7 according to the processing conditions, as shown in FIG. 4 , while irradiating the laser beam 21 toward the wafer 1 with the laser beam 21 having a wavelength that is transparent to the substrate 2 of the wafer 1 and has an absorptive property to the film 4 .

In the first embodiment, in the laser beam irradiation step 101 , as shown in FIG. 5 , the laser processing device 20 passes the laser beam to which aberration (especially longitudinal aberration) is given through the optical system of the laser beam irradiation unit 25 21 is concentrated inside the wafer 1 and irradiated. In the first embodiment, in the laser beam irradiation step 101, as shown in FIG. 5, the laser processing device 20 condenses the laser beam 21 in the focusing area 211 of the laser beam 21 (where the laser beam 21 is given aberration, especially longitudinal aberration). area) is positioned between the inside of the substrate 2 of the wafer 1 and the front surface 9 of the film 4, and the laser beam 21 is irradiated along the planned division lines 6 and 7 set on the wafer 1. In addition, in the present invention, in the laser beam irradiation step 101, the laser processing device 20 may position the focusing area 211 of the laser beam 21 from the inside of the substrate 2 of the wafer 1 to the specific film 4 as shown in FIG. 6 The front surface 9 is irradiated with the laser beam 21 along the planned division lines 6 and 7 set on the wafer 1 between the positions outside the laser beam irradiation unit 25 .

In the first embodiment, in the laser beam irradiation step 101, the laser beam 21 has a wavelength that is transparent to the wafer 1 and absorptive to the film 4, and is given aberration (especially longitudinal aberration), Therefore, as shown in FIGS. 7 and 8 , the laser processing device 20 forms the modified region 12 at intervals along the planned division lines 6 and 7 inside the substrate 2 of the wafer 1 and at the same time, spaced apart on the front surface 9 of the film 4 . The ablation marks 11 are formed at intervals. Furthermore, in the first embodiment, since aberration is given to the laser beam 21 , the modified region 12 is formed linearly along the thickness direction of the wafer 1 as shown in FIGS. 7 and 8 .

In the first embodiment, as shown in FIG. 9 , the modified region 12 includes pores 121 whose planar shape is circular and cylindrical amorphous material 122 surrounding the pores 121 . The pores 121 are holes (spaces) formed in the substrate 2 , and in the first embodiment, the diameter of the pores 121 is approximately 1 μm. The amorphous substance 122 refers to a region in which the density, refractive index, mechanical strength or other physical properties are different from the surrounding density, refractive index, mechanical strength or other physical properties. Examples of the amorphous substance 122 include a molten processed region, a cracked region, and a dielectric breakdown. In the first embodiment, the outer diameter of the amorphous material 122 is about 5 μm. The mechanical strength of the modified region 12 is lower than that of other parts of the substrate 2 .

The ablation mark 11 is a mark formed by subjecting the film 4 to ablation processing. In the first embodiment, it is a recessed portion recessed from the front surface 9 of the film 4 . In addition, in the first embodiment, the planar shape of the ablation mark 11 is circular.

In the first embodiment, in the laser beam irradiation step 101 , the wafer 1 is irradiated with the laser beam 21 having a wavelength of 1064 nm, an energy of 40 μJ, and a repetition frequency of 40 kHz while moving the holding stage 22 at 800 m/s. In addition, the energy of the laser beam 21, the repetition frequency, and the moving speed of the holding table 22 are the processing conditions of the laser beam irradiation step 101. That is, in the first embodiment, in the laser beam irradiation step 101, the processing conditions when the laser processing device 20 irradiates the first planned division line 6 with the laser beam 21 are different from the processing conditions when the second planned division line 7 is irradiated with the laser beam 21. Processing conditions are equal. In the first embodiment, in the laser beam irradiation step 101 , the laser beam 21 is irradiated along all the planned division lines 6 and 7 of the wafer 1 , and the modified regions 12 and 12 are formed along all the planned division lines 6 and 7 of the wafer 1 . Ablation marks 11.

(segmentation step)

FIG. 10 is a side view schematically showing, in partial cross-section, a state in which a wafer is held by a dividing device in the dividing step of the chip manufacturing method shown in FIG. 3 . FIG. 11 is a side view schematically showing, in partial cross-section, a state in which a wafer is divided into chips by a dividing device in the dividing step of the chip manufacturing method shown in FIG. 3 . FIG. 12 is a plan view schematically showing a chip divided in the dividing step of the chip manufacturing method shown in FIG. 3 . In addition, the device 8 is omitted in FIGS. 10 and 11 .

The dividing step 102 is a step of dividing the wafer 1 into individual chips 10 along the modified regions 12 and ablation marks 11 formed in the laser beam irradiating step 101 by applying external force to the wafer 1 after the laser beam irradiating step 101 is performed. In the dividing step 102 , as shown in FIG. 10 , the dividing device 30 holds the annular frame 14 supporting the wafer 1 inside and the outer edge portion of the belt 13 in the frame clamping portion 31 , and holds the circular frame 14 in the circular frame 31 . The rolling member 33 at the upper end of the cylindrical expansion drum 32 is in contact with the belt 13 .

In this way, in the dividing step 102 , as shown in FIG. 10 , the dividing device 30 uses the frame clamping portion 31 in a state where the belt 13 is flat across the outer edge portion and the central portion of the annular frame 14 supporting the wafer 1 . Keep. In the dividing step 102 , the dividing device 30 relatively moves the annular frame 14 and the wafer 1 in a direction intersecting (perpendicularly in the first embodiment) the front surface 5 of the wafer 1 . In the first embodiment, in the dividing step 102 , the dividing device 30 raises the expansion drum 32 so that the annular frame 14 and the wafer 1 intersect with the front surface 5 of the wafer 1 as shown in FIG. 11 (in the first embodiment) (vertical in the mode) moves relatively in the direction.

Then, the rolling member 33 presses upward from below between the outer edge of the wafer 1 of the belt 13 and the inner edge of the annular frame 14, and the belt 13 expands in the surface direction. As a result of the expansion of the belt 13, tensile forces act on the belt 13 in a radial manner. When the tensile force acts radially on the tape 13 adhered to the front surface 5 side of the wafer 1, since the wafer 1 has modified areas 12 and ablation marks 11 formed along the planned division lines 6 and 7, the substrate 2 becomes a modified area. 12 is used as the starting point, and the film 4 is divided using the ablation mark 11 as the starting point. The wafer 1 is divided along the planned dividing lines 6 and 7 into individual chips 10 shown in FIG. 12 . The individually divided chips 10 shown in FIG. 12 are picked up from the belt 13 . In addition, in the first embodiment, as shown in FIG. 12 , a plurality of semicircular recessed portions 15 are formed on the outer periphery of the chip 10 that is divided one by one to form ablation marks 11 and modified regions 12 on the wafer 1 .

In the chip manufacturing method of the first embodiment described above, in the laser beam irradiation step 101, the laser beam 21 is irradiated along the planned dividing lines 6 and 7 of the wafer 1, and the laminated film 4 is subjected to an ablation process to form an ablated film. Etch marks 11 are formed, and a modified region 12 is formed inside the substrate 2 of the wafer 1 . Therefore, in the chip manufacturing method of the first embodiment, the ablation marks 11 are formed on the film 4 laminated on the substrate 2 of the wafer 1. Therefore, in the dividing step 102, even if the cracks from the modified region 12 are not smoothly The film 4 is extended to the film 4, and the ablation trace 11 also becomes the starting point for division, so that meandering or edge chipping can be suppressed, and the wafer 1 can be reliably divided into individual chips 10.

In addition, in the chip manufacturing method of the first embodiment, in the laser beam irradiation step 101, the laser beam 21 is irradiated along the planned dividing lines 6 and 7 of the wafer 1, and the stacked film 4 is subjected to an ablation process to form an ablation process. Since the mark 11 is formed and the modified region 12 is formed inside the substrate 2 of the wafer 1, the man-hours for removing the film 4 on the planned division lines 6 and 7 in advance can be reduced, which contributes to the improvement of productivity.

As a result, the chip manufacturing method of the first embodiment has the effect of being able to reliably divide the wafer 1 with the film 4 into individual chips 10 and to improve productivity.

[Second Embodiment]

A method of manufacturing a chip according to the second embodiment will be described based on the drawings. FIG. 13 is a flowchart showing the flow of the chip manufacturing method according to the second embodiment. 14 is a cross-sectional view schematically showing a main part of the wafer irradiated with a laser beam in a modified region forming step of the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 . FIG. 15 is a cross-sectional view schematically showing the main part of the wafer after the modified region forming step of the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 . 16 is a cross-sectional view schematically showing a main part of the wafer irradiated with a laser beam in the ablation mark forming step of the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 . FIG. 17 is a cross-sectional view schematically showing the main part of the wafer after the ablation mark forming step in the laser beam irradiation step of the chip manufacturing method shown in FIG. 13 . In addition, in FIG. 13 , FIG. 14 , FIG. 15 , FIG. 16 , and FIG. 17 , the same parts as those in the first embodiment are assigned the same reference numerals, and description thereof is omitted.

The chip manufacturing method of the second embodiment is the same as the first embodiment except that the laser beam irradiation step 101 includes a modified region forming step 101-1 and an ablation mark forming step 101-2.

In the second embodiment, the modified region forming step 101-1 is to position the focusing area 211-2 (shown in FIG. 14) of the laser beam 21 having a wavelength that is transparent to the wafer 1 on the wafer 1. A step of forming a modified layer 12-2 (shown in FIG. 14) as a modified region inside the substrate 2. In the second embodiment, in the modified region forming step 101-1, the laser processing device 20 sucks and holds the front surface 5 side of the wafer 1 on the holding surface 23 of the holding table 22, similarly to the first embodiment. According to the processing conditions, the laser beam irradiation unit 25 and the wafer 1 are relatively moved along the planned dividing lines 6 and 7 while irradiating the wafer 1 from the laser beam 21, which is transparent to the wafer 1 and absorbs the film 4 Laser beam of specific wavelength 21.

In the second embodiment, in the modified region forming step 101-1, as shown in FIG. 14, the laser processing apparatus 20 does not impart aberration (especially longitudinal aberration) to the optical system of the laser beam irradiation unit 25. In this case, the focusing point 211 - 2 of the laser beam 21 is set inside the substrate 2 of the wafer 1 and irradiated. In the second embodiment, in the modified region forming step 101 - 1 , since the laser beam 21 has a wavelength that is transparent to the wafer 1 , the laser processing device 20 follows the planned division line 6 as shown in FIG. 15 , 7 forms a modified layer 12-2 at intervals inside the substrate 2 of the wafer 1.

In addition, the modified layer 12-2 refers to a region in which the density, refractive index, mechanical strength, and other physical properties are in a different state from the surrounding density, refractive index, mechanical strength, and other physical properties. Examples thereof include a melt-processed region, a cracked region, and a cracked region. areas, dielectric breakdown areas, refractive index change areas, and areas where these areas are mixed, etc. The mechanical strength of the modified layer 12 - 2 is lower than that of other parts of the substrate 2 . In the modified region forming step 101 - 1 , the laser beam 21 is irradiated along all the planned division lines 6 and 7 of the wafer 1 , and the modified layer 12 - 2 is formed along all the planned division lines 6 and 7 of the wafer 1 .

In the second embodiment, the ablation mark forming step 101-2 is performed after the modified region forming step 101-1 is performed. -2 The step of positioning the ablation mark 11 near the front surface 9 of the film 4 . In the second embodiment, in the ablation mark forming step 101-2, the laser beam irradiation unit 25 and the wafer 1 are relatively moved from the laser beam 21 to the planned division lines 6 and 7 according to the processing conditions. The wafer 1 is irradiated with a laser beam 21 of a wavelength that is transmissive to the wafer 1 and absorptive to the film 4 .

In the second embodiment, in the ablation mark forming step 101-2, as shown in FIG. 16, the laser processing apparatus 20 does not impart aberration (especially longitudinal aberration) through the optical system of the laser beam irradiation unit 25. In this case, the focusing point 211-2 of the laser beam 21 is set on the front surface 9 of the film 4 and irradiated. In the second embodiment, in the ablation mark forming step 101-2, since the laser beam 21 has a wavelength that is absorptive for the film 4, the laser processing device 20 follows the planned dividing line 6 as shown in FIG. 17. 7. Ablation marks 11 are formed at intervals on the front surface 9 of the film 4 of the wafer 1. In the ablation mark forming step 101 - 2 , the laser beam 21 is irradiated along all the planned dividing lines 6 and 7 of the wafer 1 , and the ablation marks 11 are formed along all the planned dividing lines 6 and 7 of the wafer 1 .

In addition, in the second embodiment, in the modified region forming step 101-1 and the ablation mark forming step 101-2, the laser beam 21 of the same wavelength (1064 nm in the second embodiment) is irradiated to form the modified region. However, in the present invention, the modified layer can also be formed by irradiating laser beams 21 with different wavelengths in the modified region forming step 101-1 and the ablated trace forming step 101-2. 12-2 and ablation marks 11. In this case, it is preferable to irradiate the laser beam 21 with a wavelength of 1064 nm in the modified region forming step 101-1, and to irradiate the laser beam 21 with a wavelength of 355 nm in the ablation mark forming step 101-2.

In addition, in the present invention, particularly in the modified region forming step 101-1, similarly to the first embodiment, the laser beam 21 imparted with aberration (particularly longitudinal aberration) may be irradiated to form a surface of the wafer 1. A modified region 12 is formed inside the substrate 2 . In addition, in the present invention, in the modified region forming step 101-1, the focusing point 211-2 of the laser beam 21 may be positioned closer to the inside of the substrate 2 than the front surface 9 of the film 4 or closer to the substrate 2. The position of the front surface 9 of the film 4 on the side of the laser beam irradiation unit 25 positions the focusing point 211 - 2 in the vicinity of the front surface 9 of the film 4 . In addition, "locating the light condensing point 211-2 near the front surface 9 of the film 4" means that the ablation mark 11 can be formed on the front surface 9 of the film 4 by irradiation of the laser beam 21 from the front surface 9 of the film 4. leave.

In the chip manufacturing method of the second embodiment, in the laser beam irradiation step 101, the laser beam 21 is irradiated along the planned division lines 6 and 7 of the wafer 1, and the stacked film 4 is subjected to an ablation process to form an ablation mark 11. , and a modified layer 12-2 is formed inside the substrate 2 of the wafer 1. As a result, the chip manufacturing method of the second embodiment has the effect that the wafer 1 with the film 4 can be reliably divided into individual chips 10 and productivity can be improved, similarly to the first embodiment.

In addition, the present invention is not limited to the above-described embodiments. That is, various modifications can be made without departing from the gist of the present invention. For example, in the present invention, the processing conditions when the laser beam 21 is irradiated to the first planned division line 6 may be equal to the processing conditions when the laser beam 21 is irradiated to the second planned division line 7 , or the processing conditions may be different. In addition, in the embodiment, the film 4 is formed on the back surface 3 of the wafer 1 , but in the present invention, the film 4 may be formed on the front surface 5 .

Claims (4)

1. A method for manufacturing chips, in which a wafer having a film formed on the front or back side is divided along a plurality of intersecting lines to be divided to manufacture chips,

the manufacturing method of the chip comprises the following steps:

a laser beam irradiation step of irradiating a laser beam along the dividing line set in the wafer, forming an etching mark on the film formed on the front surface or the back surface, and forming a modified region in the wafer; and

and a dividing step of applying an external force to the wafer after the laser beam irradiation step is performed, and dividing the wafer along the ablation mark formed by the laser beam irradiation step.

2. The method for manufacturing a chip according to claim 1, wherein,

in the step of irradiating the laser beam,

a laser beam is irradiated along a predetermined dividing line set in the wafer by positioning a condensed region of the laser beam having a wavelength that is transparent to the wafer and absorptive to the film at a position from the inside of the wafer to the front surface of the film or to the outside of the front surface, thereby forming a burn mark on the film simultaneously with forming a modified region in the inside of the wafer.

3. The method for manufacturing a chip according to claim 1, wherein,

the laser beam irradiation step includes the steps of:

a modified region forming step of forming a modified region by positioning a condensed region of a laser beam having a wavelength that is transparent to the wafer inside the wafer; and

and an ablation mark forming step of forming an ablation mark by positioning a condensed region of the laser beam having a wavelength that is absorptive to the film in the vicinity of the film after the modified region forming step is performed.

4. The method for manufacturing a chip according to any one of claims 1 to 3, wherein,

in the step of irradiating the laser beam,

the modified region formed inside the wafer includes pores and an amorphous state surrounding the pores.