CN110473831A - The manufacturing method of chip - Google Patents

Abstract

Provided is a method of manufacturing a chip capable of manufacturing a plurality of chips by dividing a plate-shaped workpiece without using an expansion sheet. The chip manufacturing method includes the following steps: a first laser processing step of irradiating only the chip region with a laser beam having a wavelength that is transparent to the workpiece along the planned dividing line to form a laser beam along the planned dividing line of the chip region. a first modified layer; a second laser processing step of irradiating a laser beam having a wavelength that is transparent to the workpiece along the boundary between the chip region and the peripheral remaining region to form a second modified layer along the boundary; and In the dividing step, force is applied to the workpiece to divide the workpiece into individual chips, and in the dividing step, the workpiece is divided into individual chips by applying force by heating and cooling.

Description

chip manufacturing method

technical field

The present invention relates to a method of manufacturing a chip, which divides a plate-shaped workpiece to manufacture a plurality of chips.

Background technique

In order to divide a plate-shaped workpiece (workpiece) represented by a wafer into a plurality of chips, a method is known in which a laser beam having transmissivity is condensed inside the workpiece to form a multiphoton absorption A modified modified layer (modified region) (for example, refer to Patent Document 1). Since the modified layer is brittle than other regions, the workpiece can be divided into a plurality of chips starting from the modified layer by applying a force to the workpiece after forming the modified layer along the line to divide (spacer). .

When a force is applied to the workpiece on which the modified layer is formed, for example, a method in which an expansion sheet (expanding tape) having extensibility is attached to the workpiece and expanded is employed (for example, refer to Patent Document 2). In this method, generally, before a modified layer is formed on the workpiece by irradiating a laser beam, an expansion sheet is attached to the workpiece, and after the modified layer is formed, the expansion sheet is expanded to divide the workpiece. into multiple chips.

Patent Document 1: Japanese Patent Laid-Open No. 2002-192370

Patent Document 2: Japanese Patent Laid-Open No. 2010-206136

However, in the method of expanding the expansion sheet as described above, the used expansion sheet cannot be reused, and thus the cost required to manufacture the chip tends to increase. In particular, a high-performance expansion sheet that does not easily remain on the chip as an adhesive material is also expensive, and therefore, when such an expansion sheet is used, the cost required to manufacture the chip also increases.

SUMMARY OF THE INVENTION

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

According to one aspect of the present invention, there is provided a method of manufacturing a chip, wherein a plurality of chips are manufactured from a workpiece having a chip area and a peripheral remaining area surrounding the chip area, the chip area being divided by a plurality of intersecting predetermined dividing lines A plurality of regions to be the chip, the method for manufacturing the chip is characterized by comprising the following steps: a holding step in which the workpiece is directly held by a holding table; and a first laser processing step, which is performed after the holding step Then, along the planned dividing line, only the chip of the workpiece is oriented along the planned dividing line so that the converging point of the laser beam of the wavelength having transparency to the workpiece is positioned inside the workpiece held by the holding table. The laser beam is irradiated to the area to form a first modified layer along the planned dividing line of the chip area, and the remaining peripheral area is used as a reinforcing part where the first modified layer is not formed; the second laser processing step is implemented in After the holding step, along the chip area and the peripheral remaining area so that the condensing point of the laser beam having a wavelength that is transparent to the workpiece is positioned inside the workpiece held by the holding table irradiate the laser beam along the boundary of the boundary, and form a second modified layer along the boundary; in the carrying out step, after the first laser processing step and the second laser processing step are carried out, the workpiece is carried out from the holding table; and a dividing step, after the carrying out step is performed, a force is applied to the workpiece to divide the workpiece into each of the chips, and in the dividing step, the force is applied by heating and cooling to divide the workpiece into each of the chips.

In one form of this invention, you may further have the reinforcement part removal process which removes this reinforcement part after performing this 1st laser processing process and this 2nd laser processing process and before performing this division|segmentation process. In addition, in one aspect of the present invention, the upper surface of the holding table may be made of a soft material, and in the holding step, the front side of the workpiece may be held with the soft material.

In the chip manufacturing method according to one aspect of the present invention, in a state where the workpiece is directly held by the holding table, only the chip region of the workpiece is irradiated with a laser beam to form the first line along the planned dividing line. The modified layer is formed by irradiating the boundary between the chip area and the remaining peripheral area with a laser beam to form a second modified layer along the boundary, and then applying force by heating and cooling to divide the workpiece into individual chips, so there is no need to use expansion The chip is divided into individual chips by applying force to the workpiece. In this way, according to the method for manufacturing a chip of one aspect of the present invention, a plurality of chips can be manufactured by dividing a workpiece, which is a plate-shaped workpiece, without using an expansion sheet.

In addition, in the method for manufacturing a chip according to an aspect of the present invention, only the chip region of the workpiece is irradiated with a laser beam to form the first modified layer along the line to divide, and the remaining outer peripheral region is regarded as the unformed first modified layer. Since the reinforcing portion of the modified layer is used, the chip region is reinforced by the reinforcing portion. Thereby, the to-be-processed object is not divided into individual chips by the force applied at the time of conveyance etc., and a silicon wafer can be conveyed appropriately.

Description of drawings

FIG. 1 is a perspective view schematically showing a structural example of a workpiece.

FIG. 2 is a perspective view schematically showing a configuration example of a laser processing apparatus.

FIG. 3(A) is a cross-sectional view for explaining a holding step, and FIG. 3(B) is a cross-sectional view for explaining a laser processing step.

4 is a cross-sectional view for explaining a second laser processing step.

FIG. 5(A) is a plan view schematically showing the state of the workpiece after forming the modified layer, and FIG. 5(B) is a cross-sectional view schematically showing the state of the modified layer.

FIG. 6 is a cross-sectional view for explaining a step of removing a reinforcement portion.

FIG. 7 is a cross-sectional view for explaining the dividing step.

8 is a cross-sectional view for explaining a holding step of a modification.

FIG. 9(A) is a cross-sectional view for explaining the division step of the modification, and FIG. 9(B) schematically shows the state of the workpiece before the chip region is divided by the division step of the modification Top view.

Label description

11: object to be processed (workpiece); 11a: front surface; 11b: back surface; 11c: chip area; 11d: peripheral remaining area; 13: planned dividing line (spacer); 15: area; 17: laser beam; 19, 19a , 19b, 19c, 19d: modified layer; 21: fluid; 23: crack; 25: chip; 2: laser processing device; 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 moving table; 14: X-axis ball screw; 16: X-axis pulse motor; 18: X-axis scale; 20: Y Axis guide; 22: Y-axis moving table; 24: Y-axis ball screw; 26: Y-axis pulse motor; 28: Y-axis scale; 30: Support table; 32: Valve; 34: Suction source; 36: Support structure ; 38: support arm; 40: laser irradiation unit; 42: camera; 44: sheet (porous sheet); 44a: upper surface; 52: dividing device; 54: chuck table (holding table); 54a: 54b: suction path; 54c: heater (heating unit); 56: valve; 58: suction source; 60: nozzle (cooling unit); 62: cutting unit; 64: cutting tool.

Detailed ways

An embodiment of one embodiment of the present invention will be described with reference to the drawings. The chip manufacturing method of the present embodiment includes a holding step (refer to FIG. 3(A) ), a first laser processing step (refer to FIG. 3(B) etc.), a second laser processing step (refer to FIG. 4 etc.), A carry-out step, a reinforcement part removal step (refer to FIG. 6 ), and a division step (refer to FIG. 7 ).

In the holding step, a workpiece (workpiece) having a chip region divided into a plurality of regions by a predetermined dividing line and a peripheral remaining region surrounding the chip region is directly held by a chuck table (holding table). In the first laser processing step, a laser beam having a wavelength that is transparent to the workpiece is irradiated to form a modified layer (first modified layer) along the line to be divided into the chip region, and the remaining peripheral region is regarded as unaffected. A reinforcing portion of the modified layer is formed.

In the second laser processing step, a laser beam having a wavelength having transmittance to the workpiece is irradiated to form a modified layer (second modified layer) along the boundary between the chip region and the peripheral remaining region. In the unloading step, the workpiece is unloaded from the holding table. In the reinforcement portion removing step, the reinforcement portion is removed from the workpiece. In the dividing step, the workpiece is divided into a plurality of chips by applying force by heating and cooling. Hereinafter, the manufacturing method of the chip of this embodiment is demonstrated in detail.

FIG. 1 is a perspective view schematically showing a configuration example of a workpiece (workpiece) 11 used in the present embodiment. As shown in FIG. 1 , the workpiece 11 is made of, for example, semiconductors such as silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN), and silicon carbide (SiC); sapphire (Al ₂ O ₃ ), soda-lime glass, borosilicate glass, quartz glass and other dielectrics (insulators); or ferroelectrics (ferroelectric crystals) such as lithium tantalate (LiTaO ₃ ) and lithium niobate (LiNbO ₃ ) shaped wafer (substrate).

The front surface 11 a side of the workpiece 11 is divided into a plurality of regions 15 to be chips by a plurality of intersecting planned dividing lines (spacers) 13 . Hereinafter, a substantially circular region including all of the plurality of regions 15 to be 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 remaining region 11d.

In each region 15 in the chip region 11c, an IC (Integrated Circuit), a MEMS (Micro Electro Mechanical Systems), an LED (Light Emitting Diode), and an LD (Laser Diode) are formed as necessary. diode), photodiode (Photodiode), SAW (Surface Acoustic Wave: surface acoustic wave) filter, BAW (Bulk Acoustic Wave: bulk acoustic wave) filter and other devices.

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

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

When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal substrate) formed of a ferroelectric such as lithium tantalate and lithium niobate, a chip that functions as a filter, an actuator, or the like is obtained. In addition, the material, shape, structure, size, thickness, etc. of the workpiece 11 are not limited. Likewise, there is no limit to the type, number, shape, configuration, size, arrangement, etc. of the devices formed in the region 15 to be a chip. The device may also not be formed in the area 15 that will become the chip.

In the chip manufacturing method of the present embodiment, a plurality of chips are manufactured using a disk-shaped silicon wafer as the workpiece 11 . Specifically, first, a holding step is performed, and the workpiece 11 is directly held by the chuck table. 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 has a base 4 on which each component is mounted. The upper surface of the base 4 is provided with a horizontal movement mechanism 8 for moving a chuck table (holding table) 6 for sucking and holding the workpiece 11 in the X-axis direction (processing feed direction) and the Y-axis direction (indexing feed direction). The horizontal movement mechanism 8 has a pair of X-axis guide rails 10 which are fixed to the upper surface of the base 4 and are 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 rear 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 10 is screwed to the nut portion.

An X-axis pulse motor 16 is connected to one end of the X-axis ball screw 14 . The X-axis ball screw 14 is rotated by the X-axis pulse motor 16 , so that the X-axis moving table 12 moves in the X-axis direction along the X-axis guide rail 10 . An X-axis scale 18 is provided adjacent to the X-axis guide rail 10 , and the X-axis scale 18 is used to detect the position of the X-axis moving table 12 in the X-axis direction.

A pair of Y-axis guide rails 20 that are substantially parallel to the Y-axis direction are fixed to the front surface (upper surface) of the X-axis moving table 12 . The 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 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 20 is screwed into the nut portion.

A Y-axis pulse motor 26 is connected to one end of the Y-axis ball screw 24 . The Y-axis ball screw 24 is rotated by the Y-axis pulse motor 26 , so that the Y-axis moving table 22 moves in the Y-axis direction along the Y-axis guide rail 20 . A Y-axis scale 28 is provided adjacent to the Y-axis guide rail 20 , and the Y-axis scale 28 is used to detect the position of the Y-axis moving table 22 in the Y-axis direction.

A support table 30 is provided on the front side (upper surface side) of the Y-axis moving table 22 , and the chuck table 6 is arranged above the support table 30 . The front surface (upper surface) of the chuck table 6 serves as a holding surface 6a for attracting and holding the back surface 11b side (or the front surface 11a side) of the workpiece 11 described above. The holding surface 6a is formed of, for example, a porous material having high hardness such as alumina. However, the holding surface 6a may be formed of a flexible material represented by a resin such as polyethylene or epoxy.

The holding surface 6a is connected to the suction source 34 (see FIG. 3(A) and the like) through a suction path 6b (see FIG. 3(A) and the like) formed in the chuck table 6 , the valve 32 (see FIG. 3(A) and the like), and the like. 3 (A) etc.) connection. A rotation drive source (not shown) is provided below the chuck table 6 , and the chuck table 6 is rotated about a rotation axis substantially parallel to the Z-axis direction by the rotation drive source.

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 portion of the support structure 36 , and a laser irradiation unit 40 is provided at the front end of the support arm 38 . The workpiece 11 on the chuck table 6 is irradiated with a laser beam 17 (refer to FIG. 3(B) ) of a wavelength (wavelength that is not easily absorbed) having a specific wavelength.

A camera 42 is provided at a position adjacent to the laser irradiation unit 40 , and the camera 42 images the front surface 11 a side or the back surface 11 b side of the workpiece 11 . For example, when adjusting the positions of the workpiece 11 and the laser irradiation unit 40, etc., an image formed by photographing the workpiece 11 or the like with the camera 42 is used.

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 as to appropriately process the workpiece 11 .

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

Thereby, the workpiece 11 is sucked and held on the chuck table 6 in a state in which the front surface 11a side is exposed upward. In addition, in this embodiment, as shown in FIG.3(A), the back surface 11b side of the to-be-processed object 11 is directly held by the chuck table 6. As shown in FIG. That is, in the present embodiment, it is not necessary to attach the expansion sheet to the workpiece 11 .

After the holding step, a first laser processing step of irradiating the laser beam 17 along the planned dividing line 13 to form a modified layer (first modified layer), and irradiating the laser beam along the boundary between the chip region 11c and the peripheral remaining region 11d are performed 17 to form the second laser processing step of the modified layer (second modified layer). In addition, in this embodiment, the case where a 2nd laser processing step is performed after a 1st laser processing step is demonstrated.

FIG. 3(B) is a cross-sectional view for explaining the first laser processing step, FIG. 4 is a cross-sectional view for explaining the second laser processing step, and FIG. 5(A) schematically shows the formation and modification FIG. 5(B) is a plan view of the state of the workpiece 11 after the layer 19 , and FIG. 5(B) is a cross-sectional view schematically showing the state of the modified layer 19 . In addition, in FIG. 3(B) and FIG. 4 , some of the constituent elements are represented by functional blocks.

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

Then, the laser irradiation unit 40 starts at a timing when the laser irradiation unit 40 reaches directly above one of the boundaries between the chip region 11c and the outer peripheral remaining region 11d at the two locations on the target dividing line 13 . The laser beam 17 having a wavelength having transmittance to the workpiece 11 is irradiated. In this embodiment, as shown in FIG. 3(B) , the laser beam 17 is irradiated toward the front surface 11 a of the workpiece 11 from the laser irradiation unit 40 arranged above the workpiece 11 .

The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 reaches directly above the other of the boundaries between the chip region 11 c and the outer peripheral remaining region 11 d at two locations on the intended dividing line 13 . That is, here, only the inside of the chip region 11c is irradiated with the laser beam 17 along the intended dividing line 13 as the object.

Moreover, this laser beam 17 is irradiated so that a light-converging point may be located in the inside of the to-be-processed object 11 at a predetermined depth from the front surface 11a (or the back surface 11b). In this way, by condensing the laser beam 17 having a wavelength having transmittance to the workpiece 11 inside the workpiece 11 , it is possible to modify a part of the workpiece 11 by multiphoton absorption at the condensing point and its vicinity. , the modified layer 19 (modified layer 19a and the like) serving as the starting point of division is formed.

In the first laser processing step of the present embodiment, since the laser beam 17 is irradiated only in the chip region 11c along the target line to divide 13, the laser beam 17 is formed only in the chip region 11c along the target line 13 to be divided. Substance layer 19. That is, as shown in FIG. 5(B) , in the first laser processing step, the modified layer 19 is not formed in the remaining outer peripheral region.

After the modified layer 19 is formed at a predetermined depth along the target line to divide 13 , the modified layer 19 is formed at other depths along the target line to divide 13 in the same manner. In the present embodiment, as shown in FIG. 5(B) , for example, modified layers 19 (modified layer 19a, modified layer 19a, modified layer 19a, modified layer 19a, modified layer 19a, quality layer 19b, modified layer 19c).

However, the number and position of the modified layers 19 formed along one planned dividing line 13 are not particularly limited. For example, the number of modified layers 19 formed along one planned dividing line 13 may be one. In addition, it is desirable to form the modified layer 19 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 conditions that the cracks reach both the front surface 11a and the back surface 11b. Thereby, the to-be-processed object 11 can be divided|segmented more appropriately.

After a desired number of modified layers 19 are formed along the target line to divide 13 , the above-described steps are repeated to form modified layers 19 along all other lines to be divided 13 . As shown in FIG. 5(A) , when a desired number of modified layers 19 are formed along all the lines to be divided 13 , the first laser processing step ends.

In addition, in this first laser processing step, after a desired number of modified layers 19 are formed along one planned dividing line 13, the same modified layers 19 are formed along the other planned dividing lines 13. The order and the like of the mass layers 19 are not particularly limited. For example, the modified layer 19 may be formed at the positions of the same depth in all the planned dividing lines 13, and then the modified layer 19 may be formed at positions of other depths.

When the workpiece 11 is a silicon wafer, the modified layer 19 is formed under the following conditions, for example.

Processed object: silicon wafer

Wavelength of laser beam: 1340nm

Laser beam repetition rate: 90kHz

Laser beam output: 0.1W～2W

Movement speed of chuck table (processing feed speed): 180mm/s～1000mm/s, typically 500mm/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.

Processed objects: Gallium arsenide substrate, indium phosphide substrate

Wavelength of laser beam: 1064nm

Laser beam repetition rate: 20kHz

Laser beam output: 0.1W～2W

Movement speed of chuck table (processing feed rate): 100mm/s～400mm/s, typically 200mm/s

When the workpiece 11 is a sapphire substrate, the modified layer 19 is formed under the following conditions, for example.

Object to be processed: Sapphire substrate

Wavelength of laser beam: 1045nm

Laser beam repetition rate: 100kHz

Laser beam output: 0.1W～2W

Movement speed of chuck table (processing feed speed): 400mm/s～800mm/s, typically 500mm/s

When the workpiece 11 is a ferroelectric substrate made of a ferroelectric such as lithium tantalate or lithium niobate, the modified layer 19 is formed under the following conditions, for example.

Worked objects: lithium tantalate substrate, lithium niobate substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 15kHz

Output of laser beam: 0.02W～0.2W

Movement speed of chuck table (processing feed rate): 270mm/s～420mm/s, typically 300mm/s

When the workpiece 11 is a glass substrate formed of soda lime glass, borosilicate glass, quartz glass, or the like, the modified layer 19 is formed under the following conditions, for example.

Processed objects: Soda lime glass substrate, borosilicate glass substrate, quartz glass substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 50kHz

Laser beam output: 0.1W～2W

Movement speed of chuck table (processing feed speed): 300mm/s～600mm/s, typically 400mm/s

When the workpiece 11 is a gallium nitride substrate, the modified layer 19 is formed under the following conditions, for example.

Workpiece: Gallium Nitride Substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 25kHz

Output of laser beam: 0.02W～0.2W

Movement speed of chuck table (processing feed speed): 90mm/s～600mm/s, typically 150mm/s

When the workpiece 11 is a silicon carbide substrate, the modified layer 19 is formed under the following conditions, for example.

Object to be processed: Silicon carbide substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 25kHz

Laser beam output: 0.02W to 0.2W, typically 0.1W

Movement speed of the chuck table (processing feed speed): 90mm/s～600mm/s, typically: 90mm/s in the cleavage direction of the silicon carbide substrate and 400mm/s in the non-cleavage direction

In the first laser processing 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 dividing line 13, and the modified layer 19 is not formed in the remaining peripheral region 11d. Therefore, the strength of the workpiece 11 is ensured by the remaining peripheral region 11d. As a result, the workpiece 11 is not divided into individual chips by force applied during conveyance or the like. In this way, the remaining peripheral region 11d after the first laser processing step functions as a reinforcing portion for reinforcing the chip region 11c.

In addition, in the first laser processing step of the present embodiment, since the modified layer 19 is not formed in the remaining peripheral region 11d, the workpiece 11 can be processed even if a crack extending from the modified layer 19 reaches both the front surface 11a and the back surface 11b, for example. In the state of being completely divided, each chip will not fall off or become scattered. Usually, when the modified layer 19 is formed in the workpiece 11 , the workpiece 11 expands in the vicinity of the modified layer 19 . In the present embodiment, the force of expansion due to the formation of the reformed layer 19 is made to act inward by the ring-shaped outer peripheral remaining region 11d functioning as a reinforcing portion, thereby squeezing the chips and preventing them from falling off and dispersing.

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

This laser beam 17 is irradiated so that a condensing point may be positioned at a predetermined depth from the front surface 11 a (or the back surface 11 b ) inside the workpiece 11 . In this way, by condensing the laser beam 17 having a wavelength having transmittance to the workpiece 11 inside the workpiece 11 , it is possible to modify a part of the workpiece 11 by multiphoton absorption at the condensing point and its vicinity. , the modified layer 19 (modified layer 19d) serving as the starting point of division is formed.

In the second laser processing step of the present embodiment, since the laser beam 17 is irradiated along the boundary between the chip region 11c and the peripheral remaining region 11d, the modified layer 19 is formed along the boundary. In addition, the number and position of the modified layers 19 formed along the boundary between the chip region 11c and the peripheral remaining region 11d are not particularly limited. For example, the number of reforming layers 19 formed along the boundary may be two or more.

In addition, it is desirable to form the modified layer 19 along the boundary 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 cracks reach both the front surface 11a and the back surface 11b. Thereby, the workpiece 11 can be divided more appropriately, and the outer peripheral remaining region 11d can be separated from the chip region 11c.

Specific conditions and the like for forming the modified layer 19 in the second laser processing step are not particularly limited. For example, the modified layer 19 along the boundary can be formed under the same conditions as those used to form the modified layer 19 in the first laser processing 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 processing step.

As shown in FIGS. 5(A) and 5(B) , when the annular modified layer 19 (modified layer 19d ) is formed along the boundary between the chip region 11c and the peripheral remaining region 11d, the second laser processing Step ends. In addition, in the present embodiment, the modified layer 19 (modified layer 19d ) is formed at a position of the same depth as the modified layer 19 (modified layer 19b ) formed in the first laser processing step, so that cracks are formed. The modified layer 19 (modified layer 19d) reaches the front surface 11a and the back surface 11b.

After the first laser processing step and the second laser processing step, an unloading step is performed to unload the workpiece 11 from the chuck table 6 . Specifically, for example, after sucking the entire front surface 11a of the workpiece 11 by a conveying unit (not shown) capable of sucking and holding the entire front surface 11a (or the back surface 11b) of the workpiece 11, the valve 32 is closed. , the negative pressure of the suction source 34 is cut off, and the workpiece 11 is carried out. In addition, in the present embodiment, as described above, the remaining outer peripheral region 11d functions as a reinforcing portion, so that the workpiece 11 is not divided into individual chips due to the force applied at the time of conveyance or the like, and the workpiece can be appropriately conveyed. Processed product 11.

After the unloading step, the reinforcing portion removing step is performed to remove the reinforcing portion from the workpiece 11 . FIG. 6 is a cross-sectional view for explaining a step of removing a reinforcement portion. In addition, in FIG. 6, some components are shown as functional blocks. The step of removing the reinforcement portion is performed using, for example, the dividing device 52 shown in FIG. 6 .

The dividing device 52 has a chuck table (holding table) 54 for sucking and holding the workpiece 11 . A part of the upper surface of the chuck table 54 serves as a holding surface 54a for attracting and holding the chip region 11c of the workpiece 11 . The holding surface 54a is connected to the suction source 58 via a suction passage 54b formed in the chuck table 54, a valve 56, and the like. In addition, a heater (heating means) 54c is arranged below the holding surface 54c.

The chuck table 54 is connected to a rotational drive source (not shown) such as a motor, and rotates about a rotational axis substantially parallel to the vertical direction. Moreover, the chuck table 54 is supported by a moving mechanism (not shown), and moves in the direction substantially parallel to the said holding surface 54a.

In the reinforcement portion removing step, first, the back surface 11 b of the workpiece 11 is brought into contact with the holding surface 54 a 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. Thereby, the workpiece 11 is sucked and held on the chuck table 54 in a state in which the front surface 11a side is exposed upward. In addition, 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. As shown in FIG. That is, it is not necessary to attach the expansion sheet to the workpiece 11 here.

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

After the reinforcement removal step, a division step is performed to divide the workpiece 11 into individual chips. Specifically, the workpiece 11 is divided by generating stress by heating and cooling. FIG. 7 is a cross-sectional view for explaining the dividing step. In addition, in FIG. 7, some components are shown as functional blocks.

The segmentation step continues using segmentation means 52 . As shown in FIG. 7 , the dividing device 52 further includes a nozzle (cooling unit) 60 arranged above the chuck table 54 . In the dividing step of the present embodiment, after the workpiece 11 is heated by the heater 54c provided on the chuck table 54, the cooling fluid 21 is supplied from the nozzle 60 to cool the workpiece 11, As a result, stress required for division of the workpiece 11 is generated.

As the cooling fluid 21, a liquid such as water or a gas such as air can be used, for example. When a liquid is used as the fluid 21 , the liquid may be pre-cooled to a relatively low temperature (for example, a temperature higher than the freezing point by about 0.1° C. to 10° C.). However, the type, flow rate, temperature, etc. of the fluid 21 are not particularly limited. For example, a low-temperature liquid such as liquid nitrogen that can absorb heat further by vaporization can be used.

When the workpiece 11 is heated by operating the heater 54c, and the workpiece 11 is cooled by supplying the cooling fluid 21 from the nozzle 60, the crack 23 is caused by the stress generated inside the workpiece 11. It extends from the modified layer 19 (modified layers 19a, 19b, 19c). Thereby, the workpiece 11 is divided into a plurality of chips 25 along the line to be divided 13 .

The heating and cooling conditions (temperature, time, etc.) are set according to the type and the like of the workpiece 11 . In addition, it is desirable to repeat the heating of the workpiece 11 by the heater 54 c and the cooling of the workpiece 11 by the liquid 21 supplied from the nozzle 60 until the workpiece 11 is appropriately divided.

As described above, in the present embodiment, the workpiece 11 can be divided into the individual chips 25 by applying a required force by heating and cooling. In addition, in the present embodiment, the workpiece 11 is heated and then cooled, but the workpiece 11 may be cooled and then heated. There is no particular limitation on the method of heating and cooling.

As described above, in the chip manufacturing method of the present embodiment, in a state where the workpiece (workpiece) 11 is directly held by the chuck table (holding table) 6 , only the chip of the workpiece 11 is held. The region 11c is irradiated with the laser beam 17 to form the modified layer 19 (modified layers 19a, 19b, 19c) along the line 13 to be divided, and the boundary between the chip region 11c and the peripheral remaining region 11d is irradiated with the laser beam 17 to form the modified layer 19 along the boundary The modified layer 19 (modified layer 19 d ) of the workpiece 11 is divided into the individual chips 25 by applying force by heating and cooling, so it is not necessary to divide the workpiece 11 into the individual chips 25 in order to apply force to the workpiece 11. expansion sheet. As described above, according to the chip manufacturing method of 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 expansion sheet.

In addition, in the chip manufacturing method of the present embodiment, only the chip region 11 c of the workpiece 11 is irradiated with the laser beam 17 to form the modified layer 19 (modified layers 19 a , 19 b , 19 c ) along the dividing line 13 , and the remaining peripheral region 11d is used as a reinforcing portion where the modified layer 19 (modified layers 19a, 19b, 19c) is not formed, so that the chip region 11c is reinforced by the reinforcing portion. Thereby, the workpiece 11 is not divided into the individual chips 25 due to a force applied during conveyance or the like, and the workpiece 11 can be appropriately conveyed.

In addition, this invention is not limited to the description of the said embodiment etc., Various changes can be made and implemented. For example, in the above-described embodiment, the second laser processing step is performed after the first laser processing step, but the first laser processing step may be performed after the second laser processing step. In addition, the second laser processing step may be performed in the middle of the first laser processing step.

In addition, in the above-mentioned 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 front surface 11a side, but the chuck table 6 may be used to directly hold the workpiece 11 on the workpiece. 11 is held on the front surface 11a side, and the laser beam 17 is irradiated from the back surface 11b side.

8 is a cross-sectional view for explaining a holding step of a modification. In the holding step of this modification, as shown in FIG. 8 , for example, a chuck table (holding table) 6 whose upper surface is constituted by a porous sheet (porous sheet) 44 can be used. The sheet is formed of a soft material represented by a resin such as polyethylene or epoxy.

In the chuck table 6, the front surface 11a side of the workpiece 11 is sucked and held by the upper surface 44a of the sheet 44. As shown in FIG. Thereby, damage to the device etc. formed on the front surface 11a side can be prevented. This sheet 44 is a part of the chuck table 6 and is used repeatedly together with the main body of the chuck table 6 and the like.

However, the upper surface of the chuck table 6 does not need to be formed of the above-mentioned porous sheet 44, but may be formed of a soft material at least to the extent that the device or the like formed on the front surface 11a side of the workpiece 11 is not damaged. . In addition, it is desirable that the sheet material 44 is configured to be detachable from the main body of the chuck table 6, and to be replaceable in the case of breakage or the like.

In addition, in the above-mentioned embodiment, the reinforcement part removal process is performed after the carry-out step and before the division process, but for example, the reinforcement part removal process may be performed after the first laser processing process and the second laser processing process and before the carry-out process. In addition, when the reinforcing part removing step is performed after the unloading step and before the dividing step, it is not necessary to convey the workpiece 11 after the reinforcing part removing step, so that it is easy to avoid the failure that the workpiece 11 cannot be conveyed appropriately. Happening.

Likewise, the reinforcement removal step may be performed after the division step. In this case, the chip region 11c and the peripheral remaining region 11d are more reliably divided by the thermal shock given in the dividing step, so that the reinforcing portion can be removed more easily in the subsequent reinforcing portion removing step.

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

FIG. 9(A) is a cross-sectional view for explaining the dividing step of the modified example, and FIG. 9(B) is a schematic view showing the workpiece 11 before the chip region 11 c is divided by the dividing step of the modified example. Top view of the state. In the dividing step of the modified example, before dividing the workpiece 11 into individual chips by the dividing device 52 , for example, the cutting unit 62 provided in the dividing device 52 forms a groove as a starting point of dividing in the reinforcing portion.

The cutting unit 62 has a main shaft (not shown) as a rotation axis substantially parallel to the holding surface 54a. An annular cutting tool 64 in which abrasive grains are dispersed in a bonding material is attached to one end side of the main shaft. A rotary drive source (not shown) such as a motor is connected to the other end side of the spindle, and the cutting tool 64 attached to one end side of the spindle is rotated by the force transmitted from the rotary drive source. The cutting unit 62 is supported by, for example, a lift mechanism (not shown), and the cutting tool 64 is moved in the vertical direction by the lift mechanism.

As shown in FIGS. 9(A) and 9(B) , when forming a groove as a starting point of division, for example, the above-described cutting tool 64 is rotated to cut into the remaining outer peripheral region 11d (ie, the reinforcement portion). Thereby, the groove|channel 11e which becomes the starting point of division can be formed in a reinforcement part. In addition, it is desirable that this groove 11e is formed along the line 13 to be divided, for example. By forming such a groove 11e, the chip region 11c of the workpiece 11 can be divided together with the outer peripheral remaining region 11d.

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

Claims (3)

1. A method of manufacturing a chip, wherein a plurality of chips are manufactured from a workpiece having a chip area and a peripheral remaining area surrounding the chip area, the chip area being divided into the chips to be the chips by intersecting a plurality of predetermined dividing lines multiple regions, The manufacturing method of the chip is characterized in that it has the following steps: In the holding step, the workpiece is directly held by the holding table; In the first laser processing step, after the holding step is carried out, the laser beam of the wavelength having transmissivity to the workpiece is positioned in the inside of the workpiece held by the holding table. The planned dividing line irradiates the laser beam only to the chip region of the workpiece, the first modified layer is formed along the planned dividing line of the chip region, and the remaining peripheral region is regarded as not forming the first modified layer the reinforcements; In the second laser processing step, after the holding step is carried out, the laser beam of the wavelength having transmissivity to the workpiece is positioned in the interior of the workpiece held by the holding table. The boundary between the chip area and the remaining peripheral area is irradiated with the laser beam to form a second modified layer along the boundary; a carrying-out step of carrying out the workpiece from the holding table after the first laser processing step and the second laser processing step are carried out; and a dividing step, after the carrying out step is carried out, a force is applied to the workpiece to divide the workpiece into each of the chips, In this dividing step, the workpiece is divided into individual chips by applying the force by heating and cooling. 2. The method for manufacturing a chip according to claim 1, wherein, This chip manufacturing method further includes a reinforcing portion removing step of removing the reinforcing portion after the first laser processing step and the second laser processing step and before the dividing step. 3. The method for manufacturing a chip according to claim 1 or 2, characterized in that, The upper surface of the holding table is composed of a soft material, In this holding step, the front side of the workpiece is held with the soft material.