JP7102065B2 - Chip manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a chip in which a plate-shaped workpiece is divided to manufacture a plurality of chips.

In order to divide a plate-shaped workpiece (work) represented by a wafer into a plurality of chips, a transmissive laser beam is focused inside the workpiece and modified by multiphoton absorption. A method for forming a modified layer (modified region) is known (see, for example, Patent Document 1). Since the modified layer is more brittle than other regions, the modified layer is formed along the planned division line (street) and then a force is applied to the workpiece to be processed starting from this modified layer. You can divide an object into multiple chips.

When applying force to the work piece on which the modified layer is formed, for example, a method of attaching an stretchable expanding sheet (expanding tape) to the work piece to expand it is adopted (for example, Patent Document 2). reference). In this method, usually, before irradiating a laser beam to form a modified layer on a work piece, an expand sheet is attached to the work piece, and then a modified layer is formed and then the expanded sheet is expanded. Divide the workpiece into multiple chips.

Japanese Unexamined Patent Publication No. 2002-192370 Japanese Unexamined Patent Publication No. 2010-206136

However, in the method of expanding the expanded sheet as described above, since the expanded sheet after use cannot be used again, the cost required for manufacturing the chip tends to be high. In particular, a high-performance expanded sheet in which the adhesive material does not easily remain on the chip is expensive, and therefore, using such an expanded sheet also increases the cost required for manufacturing the chip.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for manufacturing a chip capable of dividing a plate-shaped workpiece and manufacturing a plurality of chips without using an expand sheet. It is to be.

According to one aspect of the present invention, a plate-shaped workpiece having a chip region divided into a plurality of regions to be chips by a plurality of intersecting scheduled division lines and an outer peripheral surplus region surrounding the chip region on the surface. A method for manufacturing a plurality of chips from an object, wherein the holding step of directly holding the workpiece directly on a holding table so that one of the front surface and the back surface is positioned upward , and the holding step are performed. After this, the work piece is to be divided along the planned division line so that the focusing point of the laser beam having a wavelength that is transparent to the work piece is located inside the work piece held on the holding table. The laser beam is irradiated only to the chip region to form a first modified layer along the planned division line of the chip region, and the outer peripheral surplus region is reinforced so that the first modified layer is not formed. After performing the first laser processing step and the holding step, the focusing point of the laser beam having a wavelength that is transparent to the work piece is placed inside the work piece held on the holding table. A second laser processing step of irradiating the laser beam along the boundary between the chip region and the outer peripheral surplus region so as to be positioned and forming a second modified layer along the boundary, and the first laser processing step. After performing the second laser processing step, a carry-out step of carrying out the work piece including the reinforcing portion from the holding table, and after carrying out the carry-out step, a force is applied to the work piece to be processed. A division step of dividing an object into individual chips is provided, and in the division step, an ultrasonic vibration is applied to an workpiece to which a sheet is not attached to divide the workpiece into individual chips. A method of manufacturing a laser is provided.

In one aspect of the present invention, after performing the first laser machining step and the second laser machining step, and before carrying out the division step, a reinforcing portion removing step for removing the reinforcing portion is further provided and held. The step, the first laser machining step, the second laser machining step, the unloading step, the dividing step, and the reinforcing portion removing step are all positioned above the front surface and the back surface. It may be carried out in a state . Further, in one aspect of the present invention, the upper surface of the holding table is made of a flexible material, and in the holding step, the surface side of the workpiece may be held by the flexible material.

In the chip manufacturing method according to one aspect of the present invention, the first modification along the planned division line is performed by irradiating only the chip region of the workpiece with the workpiece directly held by the holding table. A quality layer is formed, a laser beam is irradiated to the boundary between the chip region and the outer peripheral surplus region to form a second modified layer along the boundary, and then ultrasonic vibration is applied to attach the workpiece to each chip. Since it is divided into individual chips, it is not necessary to use an expanding sheet to apply force to the workpiece to divide it into individual chips. As described above, according to the method for producing chips according to one aspect of the present invention, a plurality of chips can be produced by dividing a plate-shaped workpiece without using an expanding sheet.

Further, in the chip manufacturing method according to one aspect of the present invention, the laser beam is irradiated only to the chip region of the workpiece to form the first modified layer along the planned division line, and the outer peripheral surplus region is the first. Since the reinforcing portion is not formed with the modified layer, the chip region is reinforced by this reinforcing portion. Therefore, the work piece is not divided into individual chips due to the force applied during transportation or the like, and the work piece cannot be properly conveyed.

It is a perspective view which shows the structural example of the workpiece schematically. It is a perspective view which shows the structural example of a laser processing apparatus schematically. FIG. 3A is a cross-sectional view for explaining the holding step, and FIG. 3B is a cross-sectional view for explaining the first laser machining step. It is sectional drawing for demonstrating the 2nd laser machining step. FIG. 5 (A) is a plan view schematically showing the state of the workpiece after the modified layer is formed, and FIG. 5 (B) is a cross-sectional view schematically showing the state of the modified layer. Is. It is sectional drawing for demonstrating the reinforcement part removal step. 7 (A) and 7 (B) are sectional views for explaining the division step. It is sectional drawing for demonstrating the holding step which concerns on a modification. FIG. 9A is a cross-sectional view for explaining the division step according to the modification, and FIG. 9B shows the state of the workpiece before dividing the chip region in the division step according to the modification. It is a top view schematically showing.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. The chip manufacturing method according to the present embodiment includes a holding step (see FIG. 3A), a first laser machining step (see FIG. 3B, etc.), a second laser machining step (see FIG. 4), and carrying out. It includes a step, a reinforcing portion removing step (see FIG. 6), and a dividing step (see FIGS. 7 (A) and 7 (B)).

In the holding step, the workpiece (work) having the chip region divided into a plurality of regions by the planned division line and the outer peripheral surplus region surrounding the chip region is directly held by the chuck table (holding table). In the first laser machining step, the workpiece is irradiated with a laser beam having a wavelength having transparency to form a modified layer (first modified layer) along the planned division line of the chip region, and the outer periphery is formed. The surplus area is used as a reinforcing portion where the modified layer is not formed.

In the second laser machining step, the workpiece is irradiated with a laser beam having a wavelength having transparency, and a modified layer (second modified layer) is formed along the boundary between the chip region and the outer peripheral surplus region. .. In the carry-out step, the work piece is carried out from the chuck table. In the reinforcing portion removing step, the reinforcing portion is removed from the workpiece. In the dividing step, ultrasonic vibration is applied to divide the workpiece into a plurality of chips. Hereinafter, the method for manufacturing a chip according to this embodiment will be described in detail.

FIG. 1 is a perspective view schematically showing a configuration example of a work piece (work) 11 used in the present embodiment. As shown in FIG. 1, the workpiece 11 is, for example, a semiconductor such as silicon (Si), gallium arsenide (GaAs), indium phosphate (InP), gallium nitride (GaN), silicon carbide (SiC), or sapphire. Dielectrics (insulators) such as (Al ₂ O ₃ ), soda glass, borosilicate glass, and quartz glass, or strong dielectrics (strong dielectric) such as lithium tantalate (LiTa ₃ ) and lithium niobate (LiNb ₃ ). It is a disk-shaped wafer (substrate) made of (body crystal).

The surface 11a side of the workpiece 11 is divided into a plurality of regions 15 serving as chips by a plurality of intersecting planned division lines (streets) 13. In the following, a substantially circular region including all of the plurality of regions 15 serving as chips is referred to as a chip region 11c, and an annular region surrounding the chip region 11c is referred to as an outer peripheral surplus region 11d.

Each region 15 in the chip region 11c includes an IC (Integrated Circuit), a MEMS (Micro Electro Mechanical Systems), an LED (Light Emitting Diode), an LD (Laser Diode), a photodiode (Photodiode), and a SAW, if necessary. Devices such as (Surface Acoustic Wave) filters and BAW (Bulk Acoustic Wave) filters are formed.

By dividing the workpiece 11 along the planned division line 13, a plurality of chips can be obtained. Specifically, when the workpiece 11 is a silicon wafer, for example, a chip that functions as a memory, a sensor, or the like can be obtained. When the workpiece 11 is a gallium arsenide substrate, an indium phosphide substrate, or a gallium nitride substrate, for example, a chip that functions as a light emitting element, a light receiving element, or the like can be obtained.

When the workpiece 11 is a silicon carbide substrate, for example, a chip that functions as a power device or the like can be obtained. When the workpiece 11 is a sapphire substrate, for example, a chip that functions as a light emitting element or the like can be obtained. When the workpiece 11 is a glass substrate made of soda glass, borosilicate glass, quartz glass, or the like, for example, a chip that functions as an optical component or a cover member (cover glass) can be obtained.

When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal substrate) made of a ferroelectric substance such as lithium tantalate or lithium niobate, for example, a chip that functions as a filter, an actuator, or the like can be obtained. There are no restrictions on the material, shape, structure, size, thickness, etc. of the workpiece 11. Similarly, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device formed in the region 15 to be the chip. The device may not be formed in the region 15 to be a chip.

In the chip manufacturing method according to the present embodiment, a disk-shaped silicon wafer is used as the workpiece 11, and a plurality of chips are manufactured. Specifically, first, a holding step of directly holding the workpiece 11 on the chuck table is performed. FIG. 2 is a perspective view schematically showing a configuration example of the laser processing apparatus used in the present embodiment.

As shown in FIG. 2, the laser processing apparatus 2 includes a base 4 on which each component is mounted. On the upper surface of the base 4, a horizontal movement mechanism for moving a chuck table (holding table) 6 for sucking and holding the workpiece 11 in the X-axis direction (machining feed direction) and the Y-axis direction (indexing feed direction). 8 is provided. The horizontal movement mechanism 8 includes a pair of X-axis guide rails 10 fixed to the upper surface of the base 4 and substantially parallel to the X-axis direction.

An X-axis moving table 12 is slidably attached to the X-axis guide rail 10. A nut portion (not shown) is provided on the back surface side (lower surface side) of the X-axis moving table 12, and an X-axis ball screw 14 substantially parallel to the X-axis guide rail 10 is screwed into the nut portion. ing.

An X-axis pulse motor 16 is connected to one end of the X-axis ball screw 14. By rotating the X-axis ball screw 14 with the X-axis pulse motor 16, the X-axis moving table 12 moves in the X-axis direction along the X-axis guide rail 10. An X-axis scale 18 for detecting the position of the X-axis moving table 12 in the X-axis direction is installed at a position adjacent to the X-axis guide rail 10.

A pair of Y-axis guide rails 20 substantially parallel to the Y-axis direction are fixed to the surface (upper surface) of the X-axis moving table 12. A Y-axis moving table 22 is slidably attached to the Y-axis guide rail 20. A nut portion (not shown) is provided on the back surface side (lower surface side) of the Y-axis moving table 22, and a Y-axis ball screw 24 substantially parallel to the Y-axis guide rail 20 is screwed into the nut portion. ing.

A Y-axis pulse motor 26 is connected to one end of the Y-axis ball screw 24. By rotating the Y-axis ball screw 24 with the Y-axis pulse motor 26, the Y-axis moving table 22 moves in the Y-axis direction along the Y-axis guide rail 20. At a position adjacent to the Y-axis guide rail 20, a Y-axis scale 28 for detecting the position of the Y-axis moving table 22 in the Y-axis direction is installed.

A support base 30 is provided on the front surface side (upper surface side) of the Y-axis moving table 22, and a chuck table 6 is arranged on the upper portion of the support base 30. The front surface (upper surface) of the chuck table 6 is a holding surface 6a that attracts and holds the back surface 11b side (or the front surface 11a side) of the work piece 11 described above. The holding surface 6a is made of a porous material having high hardness, such as aluminum oxide. However, the holding surface 6a may be made of a flexible material typified by a resin such as polyethylene or epoxy.

The holding surface 6a is provided with a suction source 34 (FIG. 3 (A), etc.) via a suction path 6b (see FIG. 3 (A), etc.) and a valve 32 (see FIG. 3 (A), etc.) formed inside the chuck table 6. It is connected to A) etc.). A rotation drive source (not shown) is provided below the chuck table 6, and the rotation drive source rotates the chuck table 6 around a rotation axis substantially parallel to the Z-axis direction.

A columnar support structure 36 is provided behind the horizontal movement mechanism 8. A support arm 38 extending in the Y-axis direction is fixed to the upper part of the support structure 36, and a wavelength (wavelength that is difficult to be absorbed) that is transparent to the workpiece 11 is attached to the tip of the support arm 38. A laser irradiation unit 40 is provided that pulsates the laser beam 17 (see FIG. 3B) of the above and irradiates the workpiece 11 on the chuck table 6.

At a position adjacent to the laser irradiation unit 40, a camera 42 that captures an image of the front surface 11a side or the back surface 11b side of the workpiece 11 is provided. The image formed by imaging the work piece 11 or the like with the camera 42 is used, for example, when adjusting the positions of the work piece 11 and the laser irradiation unit 40.

Components such as the chuck table 6, the horizontal movement mechanism 8, the laser irradiation unit 40, and the camera 42 are connected to a control unit (not shown). The control unit controls each component so that the workpiece 11 is appropriately machined.

FIG. 3A is a cross-sectional view for explaining the holding step. In addition, in FIG. 3A, some components are shown by functional blocks. In the holding step, as shown in FIG. 3A, for example, the back surface 11b of the workpiece 11 is brought into contact with the holding surface 6a of the chuck table 6. Then, the valve 32 is opened to apply the negative pressure of the suction source 34 to the holding surface 6a.

As a result, the workpiece 11 is sucked and held by the chuck table 6 with the surface 11a side exposed upward. In this embodiment, as shown in FIG. 3A, the back surface 11b side of the workpiece 11 is directly held by the chuck table 6. That is, in the present embodiment, it is not necessary to attach the expand sheet to the workpiece 11.

After the holding step, the laser beam 17 is irradiated along the planned division line 13 to form the modified layer (first modified layer), and the laser beam 17 is subjected to the chip region 11c and the outer peripheral surplus. A second laser machining step is performed in which irradiation is performed along the boundary with the region 11d to form a modified layer (second modified layer). In this embodiment, a case where the second laser machining step is performed after the first laser machining step will be described.

FIG. 3B is a cross-sectional view for explaining the first laser machining step, FIG. 4 is a cross-sectional view for explaining the second laser machining step, and FIG. 5A is a modification. FIG. 5B is a plan view schematically showing the state of the workpiece 11 after the layer 19 is formed, and FIG. 5B is a cross-sectional view schematically showing the modified layer 19. In addition, in FIG. 3B and FIG. 4, some components are shown by functional blocks.

In the first laser machining step, first, the chuck table 6 is rotated so that, for example, the extending direction of the target division scheduled line 13 is parallel to the X-axis direction. Next, the chuck table 6 is moved to align the laser irradiation unit 40 with the extension line of the target division scheduled line 13. Then, as shown in FIG. 3B, the chuck table 6 is moved in the X-axis direction (that is, the direction in which the target division scheduled line 13 extends).

After that, when the laser irradiation unit 40 reaches just above one of the boundaries between the chip region 11c and the outer peripheral surplus region 11d existing at two locations on the target division scheduled line 13, the laser irradiation unit 40 is processed. Irradiation of the laser beam 17 having a wavelength having a transmittance to the object 11 is started. In the present embodiment, as shown in FIG. 3B, the laser beam 17 is irradiated from the laser irradiation unit 40 arranged above the workpiece 11 toward the surface 11a of the workpiece 11.

The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 reaches directly above the other boundary between the chip region 11c and the outer peripheral surplus region 11d existing at two locations on the target division scheduled line 13. That is, here, the laser beam 17 is irradiated only in the chip region 11c along the target division scheduled line 13.

Further, the laser beam 17 is irradiated so as to position a condensing point at a predetermined depth from the inner surface 11a (or back surface 11b) of the workpiece 11. In this way, by condensing the laser beam 17 having a wavelength that is transparent to the workpiece 11 inside the workpiece 11, a part of the workpiece 11 is focused at the condensing point and its vicinity. It can be modified by multiphoton absorption to form a modified layer 19 (modified layer 19a or the like) that is a starting point of division.

In the first laser machining step of the present embodiment, since the laser beam 17 is irradiated only in the chip region 11c along the target division scheduled line 13, it is modified only in the chip region 11c along the target division schedule line 13. The layer 19 is formed. That is, as shown in FIG. 5B, the modified layer 19 is not formed in the outer peripheral surplus region 11d in the first laser machining step.

After the modified layer 19 is formed at a predetermined depth along the target split line 13, the modified layer 19 is formed at a different depth along the target split line 13 in the same procedure. Form 19. In the present embodiment, as shown in FIG. 5B, for example, the modified layer 19 (modified layer 19a, modified) is located at three positions where the depths of the workpiece 11 from the front surface 11a (or the back surface 11b) are different. The quality layer 19b and the modified layer 19c) are formed.

However, there is no particular limitation on the number and positions of the modified layers 19 formed along one scheduled division line 13. For example, the number of modified layers 19 formed along one scheduled division line 13 may be one. Further, it is desirable that the modified layer 19 is formed under the condition that the crack reaches the front surface 11a (or the back surface 11b). Of course, the modified layer 19 may be formed under the condition that cracks reach both the front surface 11a and the back surface 11b. This makes it possible to divide the workpiece 11 more appropriately.

After forming the required number of modified layers 19 along the target division scheduled lines 13, the above procedure is repeated to form the modified layers 19 along all the other planned division lines 13. As shown in FIG. 5A, the first laser machining step is completed when the required number of modified layers 19 are formed along all the scheduled division lines 13.

In this first laser machining step, a required number of modified layers 19 are formed along one scheduled division line 13, and then similar modified layers 19 are formed along the other scheduled division lines 13. However, there are no particular restrictions on the order in which the modified layer 19 is formed. For example, the modified layer 19 may be formed at the same depth of all scheduled division lines 13 and then the modified layer 19 may be formed at a different depth.

When the workpiece 11 is a silicon wafer, for example, the modified layer 19 is formed under the following conditions.
Work piece: Silicon wafer Laser beam wavelength: 1340 nm
Laser beam repetition frequency: 90 kHz
Laser beam output: 0.1W to 2W
Chuck table moving speed (machining feed speed): 180 mm / s to 1000 mm / s, typically 500 mm / s

When the workpiece 11 is a gallium arsenide substrate or an indium phosphide substrate, the modified layer 19 is formed under the following conditions, for example.
Work piece: Gallium arsenide substrate, Indium phosphide substrate Laser beam wavelength: 1064 nm
Laser beam repetition frequency: 20 kHz
Laser beam output: 0.1W to 2W
Chuck table moving speed (machining feed speed): 100 mm / s to 400 mm / s, typically 200 mm / s

When the workpiece 11 is a sapphire substrate, the modified layer 19 is formed under the following conditions, for example.
Work piece: Sapphire substrate Laser beam wavelength: 1045 nm
Laser beam repetition frequency: 100 kHz
Laser beam output: 0.1W to 2W
Chuck table moving speed (machining feed speed): 400 mm / s to 800 mm / s, typically 500 mm / s

When the workpiece 11 is a ferroelectric substrate made of a ferroelectric substance such as lithium tantalate or lithium niobate, the modified layer 19 is formed under the following conditions, for example.
Work piece: Lithium tantalate substrate, Lithium niobate substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 15 kHz
Laser beam output: 0.02W to 0.2W
Chuck table moving speed (machining feed speed): 270 mm / s to 420 mm / s, typically 300 mm / s

When the workpiece 11 is a glass substrate made of soda glass, borosilicate glass, quartz glass, or the like, the modified layer 19 is formed under the following conditions, for example.
Workpiece: Soda glass substrate, borosilicate glass substrate, quartz glass substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 50 kHz
Laser beam output: 0.1W to 2W
Chuck table moving speed (machining feed speed): 300 mm / s to 600 mm / s, typically 400 mm / s

When the workpiece 11 is a gallium nitride substrate, the modified layer 19 is formed under the following conditions, for example.
Work piece: Gallium nitride substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 25 kHz
Laser beam output: 0.02W to 0.2W
Chuck table moving speed (machining feed speed): 90 mm / s to 600 mm / s, typically 150 mm / s

When the workpiece 11 is a silicon carbide substrate, the modified layer 19 is formed under the following conditions, for example.
Work piece: Silicon carbide substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 25 kHz
Laser beam output: 0.02W to 0.2W, typically 0.1W
Chuck table moving speed (machining feed rate): 90 mm / s to 600 mm / s, typically 90 mm / s in the cleavage direction of the silicon carbide substrate, 400 mm / s in the non-cleavage direction.

In the first laser machining step of the present embodiment, the modified layer 19 (modified layers 19a, 19b, 19c) is formed only in the chip region 11c along the planned division line 13, and the modified layer 19 (modified layers 19a, 19b, 19c) is modified in the outer peripheral surplus region 11d. Since the layer 19 is not formed, the strength of the workpiece 11 is maintained by the outer peripheral excess region 11d. As a result, the workpiece 11 is not divided into individual chips due to the force applied during transportation or the like. As described above, the outer peripheral surplus region 11d after the first laser machining step functions as a reinforcing portion for reinforcing the chip region 11c.

Further, in the first laser machining step of the present embodiment, the modified layer 19 is not formed in the outer peripheral surplus region 11d, so that, for example, cracks extending from the modified layer 19 reach both the front surface 11a and the back surface 11b and are covered. Even in a situation where the workpiece 11 is completely divided, each chip does not fall off or disperse. Generally, when the modified layer 19 is formed on the workpiece 11, the workpiece 11 expands in the vicinity of the modified layer 19. In the present embodiment, the expansion force generated by the formation of the modified layer 19 is applied inward in the ring-shaped outer peripheral surplus region 11d that functions as a reinforcing portion, thereby pressing each chip and causing the chips to fall off and disperse. It is preventing.

After the first laser machining step described above, a second laser machining step is performed. In this second laser machining step, first, the chuck table 6 is moved to align the laser irradiation unit 40 on the boundary line between the chip region 11c and the outer peripheral surplus region 11d. Then, as shown in FIG. 4, the chuck table 6 is rotated while irradiating the workpiece 11 with the laser beam 17 having a wavelength that has transparency from the laser irradiation unit 40. That is, in the present embodiment, the laser beam 17 is irradiated from the laser irradiation unit 40 arranged above the workpiece 11 toward the surface 11a of the workpiece 11.

The laser beam 17 is irradiated so as to position a focusing point at a position at a predetermined depth from the front surface 11a (or the back surface 11b) inside the workpiece 11. In this way, by condensing the laser beam 17 having a wavelength that is transparent to the workpiece 11 inside the workpiece 11, a part of the workpiece 11 is focused at the condensing point and its vicinity. It can be modified by multiphoton absorption to form a modified layer 19 (modified layer 19d) which is a starting point of division.

In the second laser machining step of the present embodiment, the laser beam 17 is irradiated along the boundary between the chip region 11c and the outer peripheral surplus region 11d, so that the modified layer 19 is formed along this boundary. The number and position of the modified layers 19 formed along the boundary between the chip region 11c and the outer peripheral surplus region 11d are not particularly limited. For example, the number of modified layers 19 formed along the boundary may be 2 or more.

Further, it is desirable that the modified layer 19 along this boundary is formed under the condition that the crack reaches the front surface 11a (or the back surface 11b). Of course, the modified layer 19 along the boundary may be formed under the condition that the crack reaches both the front surface 11a and the back surface 11b. As a result, the workpiece 11 can be divided more appropriately to separate the outer peripheral surplus region 11d from the chip region 11c.

There are no particular restrictions on the specific conditions for forming the modified layer 19 in the second laser machining step. For example, the modified layer 19 along the boundary can be formed under the same conditions as for forming the modified layer 19 in the first laser machining step. Of course, the modified layer 19 along the boundary may be formed under conditions different from the conditions for forming the modified layer 19 in the first laser machining step.

As shown in FIGS. 5A and 5B, when the annular modified layer 19 (modified layer 19d) along the boundary between the chip region 11c and the outer peripheral surplus region 11d is formed, the second laser is used. The machining step is completed. In the present embodiment, the modified layer 19 (modified layer 19d) is formed at a position at a depth similar to that of the modified layer 19 (modified layer 19b) formed in the first laser machining step. The cracks reach the front surface 11a and the back surface 11b from the modified layer 19 (modified layer 19d).

After the first laser machining step and the second laser machining step, a unloading step of unloading the workpiece 11 from the chuck table 6 is performed. Specifically, for example, a transfer unit (not shown) capable of sucking and holding the entire surface 11a (or back surface 11b) of the workpiece 11 sucks the entire surface 11a of the workpiece 11 and then valves. 32 is closed to shut off the negative pressure of the suction source 34, and the workpiece 11 is carried out. In the present embodiment, as described above, since the outer peripheral surplus region 11d functions as a reinforcing portion, the workpiece 11 is divided into individual chips by the force applied during transportation or the like, and the workpiece 11 is divided into individual chips. It does not prevent the 11 from being properly transported.

After the carry-out step, a reinforcing portion removing step for removing the reinforcing portion from the workpiece 11 is performed. FIG. 6 is a cross-sectional view for explaining the reinforcing portion removing step. In FIG. 6, some components are shown by functional blocks. The reinforcing portion removing step is performed using, for example, the workpiece holding device 52 shown in FIG.

The workpiece holding device 52 includes a chuck table (holding table) 54 for sucking and holding the workpiece 11. A part of the upper surface of the chuck table 54 is a holding surface 54a that sucks and holds the chip region 11c of the workpiece 11. The holding surface 54a is connected to the suction source 58 via a suction path 54b formed inside the chuck table 54, a valve 56, and the like.

The chuck table 54 is connected to, for example, a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially parallel to the vertical direction. Further, the chuck table 54 is supported by, for example, a moving mechanism (not shown) and moves in a direction substantially parallel to the holding surface 54a described above.

In the reinforcing portion removing step, first, the back surface 11b of the workpiece 11 is brought into contact with the holding surface 54a of the chuck table 54. Then, the valve 56 is opened, and the negative pressure of the suction source 58 is applied to the holding surface 54a. As a result, the workpiece 11 is sucked and held by the chuck table 54 with the surface 11a side exposed upward. In this embodiment, as shown in FIG. 6, the back surface 11b side of the workpiece 11 is directly held by the chuck table 54. That is, again, it is not necessary to attach the expand sheet to the workpiece 11.

Next, an upward force (a force away from the holding surface 54a) is applied to the outer peripheral surplus region 11d. As described above, the modified layer 19 (modified layer 19d), which is the starting point of the division, is formed at the boundary between the chip region 11c and the outer peripheral surplus region 11d. Therefore, by applying an upward force to the outer peripheral surplus region 11d, as shown in FIG. 6, the outer peripheral surplus region 11d can be lifted and removed from the chuck table 54. As a result, only the chip region 11c of the workpiece 11 remains on the chuck table 54.

After the reinforcing portion removing step, a division step of dividing the workpiece 11 into individual chips is performed. Specifically, ultrasonic vibration is applied to divide the workpiece 11. 7 (A) and 7 (B) are sectional views for explaining the division step. In addition, in FIG. 7A and FIG. 7B, some components are shown by functional blocks.

The division step is performed using, for example, the division device 72 shown in FIGS. 7 (A) and 7 (B). The dividing device 72 includes a tank 74 in which a liquid 21 such as pure water is stored. The tank 74 is formed in a size capable of accommodating the entire workpiece 11 (chip region 11c), and an ultrasonic vibrator 76 for generating ultrasonic vibration is attached to the bottom thereof. ing.

The ultrasonic vibrator 76 includes, for example, a piezoelectric material layer made of a piezoelectric material such as barium titanate, lead zirconate titanate, lithium tantalate, or lithium niobate, and a pair of electrode layers sandwiching the piezoelectric material layer. .. An AC power source 78 for supplying AC power having a predetermined frequency is connected to the electrode layer, and the ultrasonic transducer 76 vibrates at a frequency corresponding to the frequency of the AC power supplied from the AC power source 78. do.

A holding unit 80 for holding the workpiece 11 is arranged above the tank 74. A part of the lower surface side of the holding unit 80 is a contact surface 80a in contact with the front surface 11a side (or the back surface 11b side) of the workpiece 11. It is desirable that the contact surface 80a is made of a flexible material typified by a resin such as polyethylene or epoxy.

This makes it easier to prevent damage to the device or the like formed on the surface 11a side of the workpiece 11. However, there are no particular restrictions on the material of the contact surface 80a and the like. Further, at a position surrounding the contact surface 80a, an annular protrusion 80b protruding downward is provided. The protrusion 80b can prevent the workpiece 11 from scattering after being divided into individual chips, as will be described later.

Inside the holding unit 80, a suction path 80c for transmitting a negative pressure to the workpiece 11 in contact with the contact surface 80a is provided. One end side of the suction path 80c is connected to the suction source 84 via a valve 82 or the like. The other end side of the suction path 80c is opened in the contact surface 80a so that each region 15 of the workpiece 11 in contact with the contact surface 80a can be sucked. That is, the contact surface 80a is provided with a plurality of openings corresponding to each region 15.

Therefore, after the workpiece 11 is brought into contact with the contact surface 80a, the negative pressure of the suction source 84 is applied to the plurality of openings through the valve 82, the suction path 80c, etc., so that the workpiece 11 is appropriately sucked. , Can be retained. As described above, in the present embodiment, since the plurality of openings are provided at the positions corresponding to the respective regions 15, the workpiece 11 after being divided into individual chips can be appropriately sucked and held.

In the division step according to the present embodiment, first, the contact surface 80a of the holding unit 80 is brought into contact with the surface 11a side of the workpiece 11. Next, the valve 82 is opened to apply the negative pressure of the suction source 84 to the plurality of openings. As a result, the workpiece 11 is sucked and held by the holding unit 80. After that, as shown in FIG. 7A, the holding unit 80 is positioned above the tank 74.

Then, as shown in FIG. 7B, the holding unit 80 is lowered to immerse the workpiece 11 in the liquid 21 stored in the tank 74. After the holding unit 80 is sufficiently lowered, the valve 82 is closed to shut off the negative pressure of the suction source 84. As a result, as shown in FIG. 7B, the workpiece 11 is removed from the holding unit 80.

It is desirable that the amount of lowering of the holding unit 80 is adjusted so that the gap between the bottom of the tank 74 and the lower end of the protrusion 80b is smaller than the thickness of the workpiece 11. As a result, the position of the workpiece 11 is regulated by the protrusion 80b, and it becomes possible to prevent the workpiece 11 from scattering after being divided into individual chips.

Next, AC power is supplied from the AC power source 78 to the ultrasonic vibrator 76 to vibrate the ultrasonic vibrator 76. As a result, the ultrasonic vibration generated from the ultrasonic vibrator 76 is applied to the workpiece 11 via the tank 74 and the liquid 21. Then, the crack 23 extends from the modified layer 19 of the workpiece 11 by the force of the ultrasonic vibration, and the workpiece 11 is divided into a plurality of chips 25 along the planned division line 13.

The conditions of ultrasonic vibration applied to the workpiece 11 are as follows, for example.
Output: 200W
Frequency: 20kHz, 28kHz
Grant time: 30 seconds to 90 seconds

However, the conditions of ultrasonic vibration can be arbitrarily set within a range in which the workpiece 11 can be appropriately divided. After the workpiece 11 is divided into a plurality of chips 25, the surface 11a side of the workpiece 11 and the contact surface 80a are brought into contact with each other again to open the valve 82 and apply the negative pressure of the suction source 84. .. As a result, the workpiece 11 after being divided into the plurality of chips 25 can be sucked and held by the holding unit 80 and carried out to the outside of the tank 74.

As described above, in the chip manufacturing method according to the present embodiment, the work piece (work) 11 is directly held by the chuck table (holding table) 6, and the laser is applied only to the chip region 11c of the work piece 11. The beam 17 is irradiated to form a modified layer 19 (modified layers 19a, 19b, 19c) along the planned division line 13, and the laser beam 17 is irradiated to the boundary between the chip region 11c and the outer peripheral surplus region 11d. After forming the modified layer 19 (modified layer 19d) along the boundary, ultrasonic vibration is applied to divide the workpiece 11 into individual chips 25, so that a force is applied to the workpiece 11. It is not necessary to use an expand sheet to divide into individual chips 25. As described above, according to the chip manufacturing method according to the present embodiment, a plurality of chips 25 can be manufactured by dividing a silicon wafer which is a plate-shaped workpiece 11 without using an expand sheet.

Further, in the chip manufacturing method according to the present embodiment, the modified layer 19 (modified layers 19a, 19b, 19c) along the planned division line 13 by irradiating only the chip region 11c of the workpiece 11 with the laser beam 17 And the outer peripheral surplus region 11d is a reinforcing portion in which the modified layer 19 (modified layers 19a, 19b, 19c) is not formed, so that the chip region 11c is reinforced by this reinforcing portion. Therefore, the workpiece 11 is not divided into individual chips 25 due to the force applied during transportation or the like, and the workpiece 11 cannot be appropriately transported.

The present invention is not limited to the description of the above embodiment and can be modified in various ways. For example, in the above embodiment, the second laser machining step is performed after the first laser machining step, but the first laser machining step may be performed after the second laser machining step. Further, the second laser machining step can be performed in the middle of the first laser machining step.

Further, in the above embodiment, the back surface 11b side of the workpiece 11 is directly held by the chuck table 6 and the laser beam 17 is irradiated from the surface 11a side, but the surface 11a side of the workpiece 11 is chucked. It may be held directly on the table 6 and the laser beam 17 may be irradiated from the back surface 11b side.

FIG. 8 is a cross-sectional view for explaining a holding step according to a modified example. In the holding step according to this modification, as shown in FIG. 8, a chuck whose upper surface is formed of, for example, a porous sheet (porous sheet) 44 made of a flexible material typified by a resin such as polyethylene or epoxy. It is preferable to use the table (holding table) 6.

In the chuck table 6, the upper surface 44a of the sheet 44 sucks and holds the surface 11a side of the workpiece 11. This makes it possible to prevent damage to the device or the like formed on the surface 11a side. This sheet 44 is a part of the chuck table 6 and is repeatedly used together with the main body of the chuck table 6 and the like.

However, the upper surface of the chuck table 6 does not have to be formed of the above-mentioned porous sheet 44, and is at least flexible enough not to damage the device or the like formed on the surface 11a side of the workpiece 11. It suffices if it is composed of materials. Further, it is desirable that the sheet 44 is configured so that it can be attached to and detached from the main body of the chuck table 6 and can be replaced when it is damaged.

Further, in the above embodiment, the reinforcing portion removing step is performed after the carry-out step and before the division step. For example, after the first laser machining step and the second laser machining step and before the carry-out step, The reinforcing portion removing step may be performed.

Similarly, the reinforcing portion removing step can be performed at the same time as the division step or after the division step. In this case, the chip region 11c and the outer peripheral surplus region 11d are more reliably divided by the ultrasonic vibration applied in the division step, so that the reinforcement portion can be removed more easily in the reinforcement portion removal step.

Further, the step of removing the reinforcing portion can be omitted. In this case, for example, the range in which the modified layer 19 is formed in the first laser machining step and the second laser machining step is set so that the width of the reinforcing portion is about 2 mm to 3 mm from the outer peripheral edge of the workpiece 11. It is good to adjust. Further, for example, before dividing the chip region 11c in the division step, a groove serving as a starting point of division may be formed in the reinforcing portion.

FIG. 9A is a cross-sectional view for explaining the division step according to the modification, and FIG. 9B is a state of the workpiece before dividing the chip region 11c in the division step according to the modification. Is a plan view schematically showing. In the division step according to the modification, before the division device 72 applies ultrasonic vibration to the work piece 11, for example, the cutting unit 62 provided in the work piece holding device 52 is used to divide the work piece 11 into a reinforcing portion. Form a groove as a starting point.

The cutting unit 62 includes a spindle (not shown) that is a rotation axis substantially parallel to the holding surface 54a. An annular cutting blade 64 in which abrasive grains are dispersed in a binder is mounted on one end side of the spindle. A rotary drive source (not shown) such as a motor is connected to the other end side of the spindle, and the cutting blade 64 mounted on one end side of the spindle rotates by the force transmitted from the rotary drive source. The cutting unit 62 is supported by, for example, an elevating mechanism (not shown), and the cutting blade 64 is moved in the vertical direction by the elevating mechanism.

As shown in FIGS. 9A and 9B, when forming the groove serving as the starting point of the division, for example, the cutting blade 64 described above is rotated to rotate the outer peripheral excess region 11d (that is, the reinforcing portion). Make a cut in. As a result, the groove 11e, which is the starting point of the division, can be formed in the reinforcing portion. It is desirable that the groove 11e is formed, for example, along the planned division line 13. By forming such a groove 11e, the chip region 11c of the workpiece 11 can be divided together with the outer peripheral surplus region 11d.

In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

11 Work piece (work)
11a Front surface 11b Back surface 11c Chip area 11d Outer circumference surplus area 13 Scheduled division line (street)
15 Region 17 Laser Beam 19, 19a, 19b, 19c, 19d Modified Layer 21 Liquid 23 Crack 25 Chip 2 Laser Machining Equipment 4 Base 6 Chuck Table (Holding Table)
6a Holding surface 6b Suction path 8 Horizontal movement mechanism 10 X-axis guide rail 12 X-axis movement table 14 X-axis ball screw 16 X-axis pulse motor 18 X-axis scale 20 Y-axis guide rail 22 Y-axis movement table 24 Y-axis ball screw 26 Y-axis Pulse motor 28 Y-axis scale 30 Support stand 32 Valve 34 Suction source 36 Support structure 38 Support arm 40 Laser irradiation unit 42 Camera 44 Seat (porous seat)
44a Top surface 52 Work piece holding device 54 Chuck table (holding table)
54a Holding surface 54b Suction path 56 Valve 58 Suction source 62 Cutting unit 64 Cutting blade 72 Splitting device 74 Tank 76 Ultrasonic oscillator 78 AC power supply 80 Holding unit 80a Holding surface 80b Protrusion 80c Suction path 82 Valve 84 Suction source

Claims (3)

A chip region divided into a plurality of regions to be chips by a plurality of intersecting scheduled division lines and an outer peripheral surplus region surrounding the chip region are divided into two regions.On the surfaceIt is a method of manufacturing a chip that manufactures a plurality of the chips from a plate-shaped workpiece to be held.
So that one of the front surface and the back surface is positioned upward A holding step that holds the work piece directly on the holding table,
After performing the holding step, along the planned division line so as to position the focusing point of the laser beam having a wavelength that is transparent to the work piece inside the work piece held on the holding table. The laser beam is irradiated only to the chip region of the work piece to form the first modified layer along the planned division line of the chip region, and the first modified layer forms the outer peripheral surplus region. The first laser machining step, which is an unreinforced part,
After performing the holding step, the chip region and the outer peripheral surplus so as to position the focusing point of the laser beam having a wavelength that is transparent to the work piece inside the work piece held on the holding table. A second laser machining step of irradiating the laser beam along the boundary with the region to form a second modified layer along the boundary.
After performing the first laser machining step and the second laser machining step, from the holding tableIncluding the reinforcing partThe carry-out step for carrying out the work piece and
After performing the carry-out step, a division step of applying a force to the workpiece to divide the workpiece into individual chips is provided.
In the division stepFor workpieces that do not have a sheet attachedA method for manufacturing a chip, which comprises applying ultrasonic vibration to divide a work piece into individual chips. After performing the first laser machining step and the second laser machining step, and before carrying out the division step, a reinforcing portion removing step for removing the reinforcing portion is further provided.,
The holding step, the first laser machining step, the second laser machining step, the unloading step, the dividing step, and the reinforcing portion removing step are all positioned above the front surface and the back surface. It is carried out in the state of being The method for manufacturing a chip according to claim 1, wherein the chip is manufactured. The upper surface of the holding table is made of a flexible material.
The method for producing a chip according to claim 1 or 2, wherein in the holding step, the surface side of the workpiece is held by the flexible material.

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