TW201947655A - Method for manufacturing chip capable of manufacturing a plurality of chips by dividing a plate-shaped workpiece without using an expanded sheet - Google Patents

Abstract

Provided is a method for manufacturing chip, which can manufacture a plurality of chips by dividing a plate-shaped workpiece without using an expanded sheet. The method comprises a first laser processing step of irradiating a laser beam having a wavelength transparent to the workpiece on a chip region along a predetermined dividing line to form a first modified layer along the predetermined dividing line of the chip region; a second laser processing step of irradiating the laser beam having the wavelength transparent to the workpiece along a boundary between the chip region and a remaining peripheral region to form a second modified layer along the boundary; and a dividing step of dividing the workpiece into individual chips by applying a force on the workpiece. In the dividing step, the workpiece is divided into individual chips by heating and cooling for providing the force.

Description

Manufacturing method of wafer

FIELD OF THE INVENTION The present invention relates to a method for manufacturing a wafer that divides a plate-shaped workpiece to manufacture a plurality of wafers.

BACKGROUND OF THE INVENTION In order to divide a plate-shaped workpiece (workpiece) typified by a wafer into a plurality of wafers, a method is known in which a penetrating laser beam is focused inside the workpiece, A modified layer (modified region) modified by multiphoton absorption is formed (see, for example, Patent Document 1). The reformed layer is more fragile than other areas. Therefore, by forming a reformed layer along a predetermined dividing line (cutting path) and then applying force to the workpiece, the reformed layer can be used as a starting point to The workpiece is divided into a plurality of wafers.

When a force is applied to the object on which the modified layer is formed, for example, a method can be adopted in which a stretchable expansion sheet (extension tape) is adhered to the object to be expanded (see, for example, Patent Document 2). In this method, before the laser beam is irradiated to form a modified layer in the workpiece, the expansion sheet is adhered to the workpiece, and after the modified layer is formed, the expansion sheet is expanded to expand the workpiece. Divided into multiple wafers.
Prior art literature patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2002-192370 Patent Document 2: Japanese Patent Laid-Open No. 2010-206136

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, in the method of expanding the expansion sheet as described above, since the used expansion sheet cannot be used again, it is also easy to increase the cost required for manufacturing the wafer. In particular, since a high-performance expansion sheet that makes it difficult for the adhesive to remain on the wafer is also expensive, if such an expansion sheet is used, the cost required for the manufacture of the wafer will also increase.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a method for manufacturing a wafer, which can divide a plate-like workpiece into a plurality of wafers without using an expansion sheet.
Means to solve the problem

According to an aspect of the present invention, a wafer manufacturing method can be provided, in which a plurality of wafers are manufactured from a processed object, the processed object has a plurality of divided predetermined line regions divided by a plurality of intersecting predetermined line regions to become the wafer And a remaining region of the periphery surrounding the wafer region, the method for manufacturing the wafer includes:
A holding step to keep the worktable directly holding the workpiece;
The first laser processing step is to position the condensing point of the laser beam having a wavelength penetrating to the workpiece after the holding step is performed on the inside of the workpiece held on the holding table. To irradiate the laser beam only along the predetermined division line to the wafer region of the workpiece, and form a first modified layer along the predetermined division line of the wafer region, and set the remaining peripheral region to A reinforcing portion without the first modified layer;
The second laser processing step is to position the condensing point of the laser beam having a wavelength penetrating to the workpiece after the holding step is performed on the inside of the workpiece held on the holding table. Way to irradiate the laser beam along a boundary between the wafer region and the remaining area around the periphery, and form a second modified layer along the boundary;
A carrying-out step, after carrying out the first laser processing step and the second laser processing step, carrying out the processed object from the holding table; and a dividing step, applying force to the processed object after carrying out the carrying-out step To divide the processed object into individual wafers,
In the dividing step, the force is applied by heating and cooling to divide the workpiece into the wafers.

In one aspect of the present invention, a reinforcing portion removing step may be further provided. The reinforcing portion removing step is performed after the first laser processing step and the second laser processing step are performed, and before the dividing step is performed. , Remove the reinforcing part. Furthermore, 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 surface of the workpiece is held by the soft material. side.
Invention effect

In the manufacturing method of the wafer of one aspect of the present invention, the laser beam is irradiated to only the wafer region of the processed object in a state where the processed object is directly held by the holding table, so that it is formed along a predetermined division line The first modified layer is formed by irradiating a laser beam at the boundary between the wafer region and the remaining area around the periphery. After forming the second modified layer along the boundary, the object is divided by heating and cooling to impart force. Since wafers are formed one by one, it is not necessary to use an expansion sheet in order to apply a force to the object to be divided into individual wafers. As described above, according to one aspect of the method for manufacturing a wafer of the present invention, a plate-shaped workpiece, that is, a workpiece can be divided without using an expansion sheet to manufacture a plurality of wafers.

In the wafer manufacturing method according to one aspect of the present invention, a laser beam is irradiated only to a wafer region of a workpiece to form a first modified layer along a predetermined division line, and the remaining peripheral region is set. Since the reinforcing portion without the first modified layer is formed, the wafer region can be reinforced by the reinforcing portion. Accordingly, there is no case where the object to be processed is divided into individual wafers due to a force applied at the time of transfer or the like, and the object to be processed cannot be appropriately transferred.

Embodiments for Implementing the Invention An embodiment of one aspect of the present invention will be described with reference to the attached drawings. The method for manufacturing a wafer according to this embodiment includes a holding step (see FIG. 3 (A)), a first laser processing step (see FIG. 3 (B), etc.), a second laser processing step (see FIG. 4 and the like), and carrying out A step, a reinforcing portion removing step (see FIG. 6), and a dividing step (see FIG. 7).

In the holding step, the workpiece (workpiece) is directly held by a work chuck (holding table). The workpiece has a wafer region that is divided into a plurality of regions by dividing a predetermined line, and an outer periphery surrounding the wafer region. The remaining area. In the first laser processing step, a laser beam having a wavelength penetrating the object to be processed is irradiated, and a modified layer (first modified layer) is formed along a predetermined division line of the wafer region, and the outer periphery is changed. The remaining area is a reinforcing portion where no modified layer is formed.

In the second laser processing step, a laser beam having a wavelength penetrating to the object to be processed is irradiated, and a modified layer (second modified layer) is formed along the boundary between the wafer region and the remaining peripheral region. The unloading step is to unload the workpiece from the work clamp. In the reinforcing portion removing step, the reinforcing portion is removed from the workpiece. In the dividing step, force is applied by one cooling or heating to divide the workpiece into a plurality of wafers. Hereinafter, a method for manufacturing a wafer according to this embodiment will be described 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 a semiconductor such as silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), or sapphire ( al ₂ O _3), soda glass, borosilicate glass, quartz glass, the dielectric (insulator), or lithium tantalate (LiTaO _3), lithium niobate (LiNbO ₃₎ or the like ferroelectric (Fe Disc-shaped wafers (substrates) formed by electrical crystals.

The front surface 11a side of the processed object 11 is divided into a plurality of regions 15 to be a wafer by a plurality of intersecting division lines (cutting lines) 13. In the following description, a substantially circular region including all of the plurality of regions 15 forming a wafer is referred to as a wafer region 11c, and a ring-shaped region surrounding the wafer region 11c is referred to as a peripheral remaining region 11d.

IC (Integrated Circuit), MEMS (Micro Electro Mechanical Systems), and LED (Light Emitting Diode) can be formed in each region 15 in the wafer region 11c as needed. ), LD (Laser Diode), Photodiode, SAW (Surface Acoustic Wave) Filter, BAW (Bulk Acoustic Wave) Filter and other devices.

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

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

When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal substrate) formed of a ferroelectric material such as lithium tantalate or lithium niobate, it can be obtained, for example, as a filter or an actuator. Functional chip. In addition, the material, shape, structure, size, thickness, etc. of the workpiece 11 are not limited. Similarly, the type, number, shape, structure, size, arrangement, etc. of the devices formed on the region 15 to be a wafer are not limited. The device 15 may not be formed on the region 15 to be a wafer.

In the wafer manufacturing method of this embodiment, a plurality of wafers are manufactured by using a disc-shaped silicon wafer as the workpiece 11. Specifically, first, a holding step of directly holding the workpiece 11 by a work clamp is performed. FIG. 2 is a perspective view schematically showing a configuration example of a laser processing apparatus used in this embodiment.

As shown in FIG. 2, the laser processing apparatus 2 includes a base 4 on which each constituent element is mounted. A horizontal movement mechanism 8 is provided on the upper surface of the base table 4. The horizontal movement mechanism 8 allows the work clamp table (holding table) 6 for attracting and holding the workpiece 11 in the X-axis direction (processing feed direction). And Y-axis direction (index feed direction). 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 mounted on the X-axis guide 10. A nut portion (not shown) is provided on the back 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 into the nut portion.

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 can move along the X-axis guide 10 in the X-axis direction. An X-axis scale 18 is provided at a position adjacent to the X-axis guide 10 for detecting the position of the X-axis moving table 12 in the X-axis direction.

A pair of Y-axis guides 20 are fixed to the front (upper surface) of the X-axis moving table 12 in a direction substantially parallel to the Y-axis direction. A Y-axis moving table 22 is slidably mounted on the Y-axis guide 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 that is 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. By rotating the Y-axis ball screw 24 with the Y-axis pulse motor 26, the Y-axis moving table 22 can move in the Y-axis direction along the Y-axis guide 20. A Y-axis scale 28 is provided at a position adjacent to the Y-axis guide 20 for detecting 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 a work clamp table 6 is arranged above the support table 30. The front surface (upper surface) of the work table 6 is a holding surface 6a that attracts and holds the back surface 11b side (or front surface 11a side) of the workpiece 11 described above. The holding surface 6a is made of a porous material having a high hardness such as alumina. Among them, the holding surface 6a may be formed of a soft material typified by a resin such as polyethylene or epoxy.

This holding surface 6a is connected to the suction source 34 (see FIG. 3 (A) and the like) or the valve 32 (see FIG. 3 (A) and the like) formed through the suction path 6b (see FIG. 3 (A) and the like) formed inside the work table 6. 3 (A), etc.). A rotary drive source (not shown) is provided below the work clamp table 6, and the work clamp 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 moving mechanism 8. A support arm 38 extending in the Y-axis direction is fixed to an upper portion of the support structure 36. A laser irradiation unit 40 is provided at a front end portion of the support arm 38. The laser irradiation unit 40 generates pulsed vibrations on the workpiece 11. A laser beam 17 (see FIG. 3 (B)) having a penetrating wavelength (a wavelength that is difficult to be absorbed) is irradiated onto the workpiece 11 on the work clamp 6.

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

The constituent elements of the work table 6, the horizontal movement mechanism 8, the laser irradiation unit 40, the camera 42, and the like are connected to a control unit (not shown). The control unit controls each constituent element to appropriately process the workpiece 11.

FIG. 3 (A) is a cross-sectional view for explaining a holding step. In addition, in FIG. 3 (A), a part of the constituent elements are shown 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 work clamp table 6. Then, the valve 32 is opened so that the negative pressure of the suction source 34 acts on the holding surface 6a.

Thereby, the to-be-processed object 11 is attracted and hold | maintained on the work clamp table 6 in the state which exposed the front side 11a side upwards. Furthermore, in this embodiment, as shown in FIG. 3 (A), the back surface 11b side of the workpiece 11 is directly held by the work clamp table 6. That is, in this embodiment, it is not necessary to stick 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 division line 13 to form a modified layer (first modified layer), and performing the laser beam 17 along the wafer region 11c is performed. The second laser processing step of irradiating the boundary with the remaining area 11d to form a modified layer (second modified layer). In addition, in this embodiment, a case where the second laser processing step is performed after the first laser processing step will be described.

FIG. 3 (B) is a cross-sectional view for explaining a first laser processing step, FIG. 4 is a cross-sectional view for explaining a second laser processing step, and FIG. 5 (A) is a schematic view showing a formation modification FIG. 5B is a cross-sectional view schematically showing a state of the workpiece 11 after the texture layer 19 and the modified layer 19. In addition, in FIG. 3 (B) and FIG. 4, a part of structural requirements are shown by a functional block.

In the first laser processing step, first, the work table 6 is rotated to set, for example, the extension direction of the target division line 13 to be parallel to the X-axis direction. Next, the work clamp stage 6 is moved, and the position of the laser irradiation unit 40 is aligned on the extension line of the target division line 13. Then, as shown in FIG. 3 (B), the work clamp table 6 is moved in the X-axis direction (that is, the extending direction of the target division line 13).

After that, the laser irradiation unit 40 has reached the time just above one side of the boundary between the wafer region 11c and the remaining peripheral region 11d at the target dividing line 13 at two points, and from this laser irradiation unit 40 starts to irradiate the laser beam 17 having a wavelength of penetrability to the workpiece 11. In the present embodiment, as shown in FIG. 3 (B), the laser beam 17 is irradiated from the laser irradiation unit 40 disposed above the workpiece 11 toward the front surface 11 a of the workpiece 11.

This laser beam 17 is irradiated until the laser irradiation unit 40 reaches directly above the other side of the boundary between the wafer region 11c and the remaining peripheral region 11d on the target division line 13 at two places. That is, here, the laser beam 17 is irradiated along the target division line 13 and only in the wafer region 11c.

In addition, this laser beam 17 is irradiated so that the light-condensing point is positioned inside the workpiece 11 at a predetermined depth from the front surface 11a (or the rear surface 11b). In this way, the laser beam 17 having a wavelength penetrating to the workpiece 11 can be condensed inside the workpiece 11 so that the workpiece 11 can be absorbed by multiphotons at or near the condensing point. A part of the modified layer is modified to form the modified layer 19 (the modified layer 19a, etc.) which is the starting point of the division.

In the first laser processing step of this embodiment, since the laser beam 17 is irradiated along the target division line 13 and is only radiated in the wafer region 11c, the target laser beam can be moved along the target division line 13 only. A modified layer 19 is formed in the wafer region 11c. That is, as shown in FIG. 5 (B), in the first laser processing step, the modified layer 19 is not formed in the remaining peripheral area 11d.

After the modified layer 19 is formed at a predetermined depth position along the target division line 13, the modified layer 19 is formed at other depth positions along the target division line 13 in the same process. As shown in FIG. 5 (B), in this embodiment, for example, the modified layer 19 is formed at three positions with different depths from the front surface 11a (or the rear surface 11b) (the modified layer 19a, Modified layer 19b, modified layer 19c).

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

After the required number of modified layers 19 is formed along the target division line 13, the above-mentioned steps are repeated, and the modified layers 19 are formed along all other planned division lines 13. As shown in FIG. 5 (A), when the required number of modified layers 19 is formed along all the planned division lines 13, the first laser processing step ends.

Furthermore, in this first laser processing step, although the required number of modified layers 19 is formed along one planned division line 13, the same modified layers 19 are formed along the other planned division lines 13. However, the order of forming the modified layer 19 is not particularly limited. For example, after the modified layer 19 is formed at the same depth position of all the division lines 13, the modified layer 19 may be formed at another depth position.

When the processed object 11 is a silicon wafer, the modified layer 19 is formed under the following conditions, for example.
Processed object: Silicon wafer laser beam wavelength: 1340nm
Laser beam repetition frequency: 90kHz
Laser beam output: 0.1W ~ 2W
Work clamp moving speed (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 object: GaAs substrate, InP substrate wavelength of laser beam: 1064nm
Laser beam repetition frequency: 20kHz
Laser beam output: 0.1W ~ 2W
Moving speed of work clamp (processing feed speed): 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.
Processed object: Sapphire substrate laser beam wavelength: 1045nm
Laser beam repetition frequency: 100kHz
Laser beam output: 0.1W ~ 2W
Work clamp moving speed (processing feed speed): 400mm / s ~ 800mm / s, typically 500mm / s

When the workpiece 11 is a ferroelectric substrate formed of a ferroelectric material such as lithium tantalate or lithium niobate, the modified layer 19 is formed under the following conditions, for example.
Processed object: lithium tantalate substrate, lithium niobate substrate laser beam wavelength: 532nm
Laser beam repetition frequency: 15kHz
Laser beam output: 0.02W ~ 0.2W
Work clamp moving speed (processing feed speed): 270mm / s ~ 420mm / s, typically 300mm / s

When the workpiece 11 is a glass substrate formed of soda glass, borosilicate glass, quartz glass, or the like, the modified layer 19 is formed under the following conditions, for example.
Processed object: Sodium glass substrate, borosilicate glass substrate, quartz glass substrate Laser beam wavelength: 532nm
Laser beam repetition frequency: 50kHz
Laser beam output: 0.1W ~ 2W
Work clamp moving speed (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.
Processed object: GaN substrate laser beam wavelength: 532nm
Laser beam repetition frequency: 25kHz
Laser beam output: 0.02W ~ 0.2W
Movement speed of work clamp (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.
Processed object: Silicon carbide substrate Laser beam wavelength: 532nm
Laser beam repetition frequency: 25kHz
Laser beam output: 0.02W ~ 0.2W, typically 0.1W
Movement speed of the work table (processing feed rate): 90mm / s ~ 600mm / s, typically 90mm / s in the cleaving direction of the silicon carbide substrate and 400mm / s in the non-cleaving direction

In the first laser processing step of this embodiment, since the modified layer 19 (modified layers 19a, 19b, and 19c) is formed only in the wafer region 11c along the planned division line 13, the remaining region 11d is on the outer periphery. Since the modified layer 19 is not formed, the strength of the workpiece 11 can be maintained by the remaining peripheral area 11d. Thereby, there is no case where the workpiece 11 is divided into individual wafers due to a force applied during transportation or the like. In this way, the remaining peripheral area 11d after the first laser processing step functions as a reinforcing portion for reinforcing the wafer area 11c.

In the first laser processing step of the present embodiment, since the modified layer 19 is not formed in the remaining area 11d of the outer periphery, even if, for example, a crack extended from the modified layer 19 reaches both the front surface 11a and the back surface 11b, On the other hand, when the workpiece 11 is completely divided, each wafer does not fall off or disperse. Generally, when the modified layer 19 is formed on the processed object 11, the processed object 11 swells in the vicinity of the modified layer 19. In this embodiment, the ring-shaped outer peripheral area 11d functioning as a reinforcing portion allows the expansion force generated by the formation of the reforming layer 19 to act inward, thereby suppressing each wafer and preventing It falls off and disperses.

The second laser processing step is performed after the first laser processing step. In this second laser processing step, first, the work table 6 is moved, and the position of the laser irradiation unit 40 is aligned on the boundary line between the wafer region 11c and the remaining peripheral region 11d. Then, as shown in FIG. 4, while radiating a laser beam 17 having a wavelength penetrating to the workpiece 11 from the laser irradiation unit 40, the work table 6 is rotated. That is, in the present embodiment, the laser beam 17 is irradiated from the laser irradiation unit 40 disposed above the workpiece 11 toward the front surface 11 a of the workpiece 11.

This laser beam 17 is irradiated so that the light-condensing point is positioned inside the workpiece 11 at a predetermined depth from the front surface 11a (or the rear surface 11b). In this way, the laser beam 17 having a wavelength penetrating to the workpiece 11 can be condensed inside the workpiece 11 so that the workpiece 11 can be absorbed by multiphotons at or near the condensing point. A part of the modified layer is modified to form a modified layer 19 (modified layer 19d), which is the starting point of division.

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

Further, it is preferable that the modified layer 19 along this boundary is formed under conditions that the cracks reach the front surface 11a (or the back surface 11b). Of course, the modified layer 19 along the boundary may be formed under conditions that the cracks reach both sides of the front surface 11a and the back surface 11b. Thereby, it becomes possible to divide the workpiece 11 more appropriately, and it is possible to separate the remaining peripheral area 11d from the wafer area 11c.

The 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 conditions different from the conditions for forming the modified layer 19 in the first laser processing step may be used to form the modified layer 19 along the boundary.

As shown in FIGS. 5 (A) and 5 (B), when a ring-shaped modified layer 19 (modified layer 19d) is formed along the boundary between the wafer region 11c and the remaining peripheral region 11d, the second laser processing step is performed. That's it. In this embodiment, the modified layer 19 (modified layer 19d) is formed at the same depth position as the modified layer 19 (modified layer 19b) formed in the first laser processing step. Then, the cracks are made from the modified layer 19 (modified layer 19d) to the front surface 11a and the back surface 11b.

After the first laser processing step and the second laser processing step, a carrying-out step of carrying out the workpiece 11 from the work clamp 6 is performed. Specifically, for example, the entire front surface 11a of the workpiece 11 is adsorbed by a transfer unit (not shown) that can adsorb and hold the entire front surface 11a (or the rear surface 11b) of the workpiece 11, and then the valve 32 is closed to close the valve 32. The negative pressure of the suction source 34 is blocked, and the workpiece 11 is carried out. Furthermore, in this embodiment, as described above, since the remaining peripheral area 11d functions as a reinforcing portion, there is no case where the workpiece 11 is damaged due to a force applied during transportation or the like. Since the wafer is divided into individual wafers, the workpiece 11 cannot be properly transferred.

After the unloading step, a reinforcing portion removing step of removing the reinforcing portion from the workpiece 11 is performed. FIG. 6 is a cross-sectional view for explaining a step of removing a reinforcing portion. In addition, in FIG. 6, a part of the constituent elements is shown by functional blocks. The reinforcing portion removal step is performed using, for example, the dividing device 52 shown in FIG. 6.

The dividing device 52 includes a work clamp (holding table) 54 for sucking and holding the workpiece 11. A part of the upper surface of this work table 54 is a holding surface 54 a that becomes a wafer region 11 c that attracts and holds the workpiece 11. The holding surface 54 a is connected to the suction source 58 through a suction path 54 b, a valve 56, or the like formed inside the work clamp 54. A heater (heating unit) 54c is disposed below the holding surface 54a.

This work clamp 54 is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially parallel to the vertical direction. The work clamp 54 is supported by a moving mechanism (not shown) and moves in a direction substantially parallel to the holding surface 54a.

In the reinforcing 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 work clamp 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 to-be-processed object 11 is attracted and hold | maintained on the work clamp 54 in the state which the front side 11a side was exposed upwards. In this embodiment, as shown in FIG. 6, the back surface 11 b side of the workpiece 11 is directly held by the work clamp 54. That is, there is no need to adhere the expansion sheet to the workpiece 11 here.

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

The step of removing the reinforcing portion is followed by a dividing step of dividing the workpiece 11 into individual wafers. Specifically, stress is generated by heating and cooling to divide the workpiece 11. FIG. 7 is a cross-sectional view for explaining a division step. In addition, in FIG. 7, a part of the constituent elements is shown by functional blocks.

The division step is continued using the division device 52. As shown in FIG. 7, the dividing device 52 further includes a nozzle (cooling unit) 60 disposed above the work table 54. In the dividing step of this embodiment, after the workpiece 11 is heated by a heater 54c provided on the work table 54, the cooling fluid 21 is supplied from the nozzle 60 to cool the workpiece 11, thereby generating the Necessary stress for dividing the processed product.

As the cooling fluid 21, for example, a liquid such as water or a gas such as air can be used. When a liquid is used as the fluid 21, it is preferable to cool the liquid in advance to a relatively low temperature (for example, a temperature that is about 0.1 ° C to 10 ° C higher than the freezing point) in advance. However, the type, flow rate, temperature, and the like of the fluid 21 are not particularly limited. It is preferable to use a low-temperature liquid such as liquid nitrogen that can further capture heat by vaporization.

After the heater 54c is operated to heat the workpiece 11, when the cooling fluid is supplied from the nozzle 60 to cool the workpiece 11, the crack 23 is changed from the stress generated in the workpiece 11 by the stress generated inside the workpiece 11. The texture layer 19 (reformed layers 19a, 19b, and 19c) is elongated. This allows the workpiece 11 to be divided into a plurality of wafers 25 along a predetermined division line 13.

Conditions for heating and cooling (temperature, time, etc.) are set in accordance with the type and the like of the workpiece 11. Further, it is desirable that the heating of the workpiece 11 by the heater 54 c and the cooling of the workpiece 11 by the fluid 21 supplied from the nozzle 60 are repeated until the workpiece is appropriately divided. Up to 11.

As described above, in this embodiment, the required force can be imparted by heating and cooling to divide the workpiece 11 into individual wafers 25. In the present embodiment, although the workpiece is cooled after being heated, the workpiece 11 may be heated after being cooled. There are also no particular restrictions on the method of heating and cooling.

As described above, in the method for manufacturing a wafer of this embodiment, since the workpiece (workpiece) 11 is directly held by the work clamp (holding table) 6, only the wafer area of the workpiece 11 is held. 11c irradiates a laser beam 17 to form a modified layer 19 (modified layers 19a, 19b, and 19c) along a predetermined division line 13, and irradiates the laser beam 17 at the boundary between the wafer region 11c and the remaining peripheral region 11d, After forming the modified layer 19 (modified layer 19d) along the boundary, heating and cooling are used to impart force to divide the workpiece 11 into individual wafers 25, so there is no need to order the workpiece 11 A force is applied to divide the wafer 25 into individual wafers 25 and an expansion wafer is used. As described above, according to the wafer manufacturing method of this embodiment, the silicon wafer, which is a plate-like object 11 to be processed, can be divided without using an expansion sheet to manufacture a plurality of wafers 25.

Further, in the method for manufacturing a wafer of this embodiment, since a laser beam 17 is irradiated to only the wafer region 11c of the workpiece 11, a modified layer 19 (modified layers 19a, 19b, And 19c), and the remaining area 11d in the outer periphery is a reinforcing portion where the modified layer 19 (modified layers 19a, 19b, and 19c) is not formed. Therefore, the wafer area 11c can be reinforced by this reinforcing portion. According to this, there is no case where the workpiece 11 is divided into individual wafers 25 due to a force applied during transportation or the like, and the workpiece 11 cannot be appropriately transferred.

In addition, the present invention is not limited by the description of the above-mentioned embodiments and the like, and can be implemented with various changes. For example, in the above 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. The second laser processing step may be performed in the middle of the first laser processing step.

Moreover, in the above-mentioned embodiment, although the back surface 11b side of the to-be-processed object 11 is directly held by the work clamp 6 and the laser beam 17 is irradiated from the front surface 11a side, it is also possible to hold the work directly by the work clamp 6 The object 11 is irradiated with the laser beam 17 from the front surface 11a side and from the rear surface 11b side.

FIG. 8 is a cross-sectional view for explaining a holding step according to a modification. In the holding step of this modification, as shown in FIG. 8, a porous sheet (porous sheet) formed of, for example, a soft material represented by a resin such as polyethylene or epoxy may be used. 44 to form a work clamp table (holding table) 6 on the upper surface.

The work table 6 is formed to attract and hold the front surface 11 a side of the workpiece 11 by the upper surface 44 a of the sheet 44. Thereby, breakage of a device or the like formed on the front surface 11a side can be prevented. This sheet 44 is a part of the work clamp table 6 and can be repeatedly used together with the body of the work clamp table 6 and the like.

However, the upper surface of the work table 6 does not necessarily need to be constituted by the porous sheet 44 described above, as long as it does not cause damage to at least the devices and the like formed on the front surface 11a side of the workpiece 11. It may be made of a soft material. In addition, it is preferable that the sheet 44 is configured to be attachable to and detachable from the main body of the work clamp table 6 and can be replaced in the case of damage or the like.

In the above-mentioned embodiment, although the reinforcing portion removing step is performed after the unloading step and before the dividing step, it may be performed, for example, after the first laser processing step and the second laser processing step and before the unloading step. Reinforcing part removal step. Furthermore, when the reinforcing portion removing step is performed after the carrying-out step and before the dividing step, it is not necessary to transfer the processed object 11 after the reinforcing portion removing step, so it is easy to avoid being unable to properly transfer the processed object 11 and the like. Bad condition.

Similarly, the reinforcing portion removing step may be performed after the dividing step. In this case, since the wafer region 11c and the outer peripheral region 11d can be more reliably divided by the thermal shock imparted in the dividing step, it can be more easily removed in the subsequent reinforcing portion removing step. Reinforcement Department.

The step of removing the reinforcing portion may be omitted. In this case, it is preferable to adjust the range for forming the modified layer 19 in the first laser processing step and the second laser processing step so that, for example, the width of the reinforcing portion is about 2 mm to 3 mm from the outer periphery of the workpiece 11. . Further, for example, before the wafer region 11c is divided in the division step, a groove that is a starting point of division may be formed in the reinforcing portion.

FIG. 9 (A) is a cross-sectional view for explaining a dividing step of a modified example, and FIG. 9 (B) is a schematic view showing a state of a workpiece before the wafer region 11c is divided in the dividing step of the modified example Floor plan. In the dividing step of the modified example, before the workpiece 11 is divided into individual wafers by the dividing device 52, for example, a cutting unit 62 provided in the dividing device 52 can be used to form a groove as a starting point of division in the reinforcing portion. .

The cutting unit 62 includes a main shaft (not shown), and the main shaft is a rotation axis that is substantially parallel to the holding surface 54a. An annular cutting blade 64 is attached to one end side of the main shaft, and the annular cutting blade 64 is configured by dispersing abrasive particles in a bonding material. A rotary drive source (not shown) such as a motor is connected to the other end side of the main shaft, and the cutting blade 64 mounted on one end side of the main shaft is rotated by a force transmitted from the rotary drive source. The cutting unit 62 is supported by, for example, a lifting mechanism (not shown), and the cutting blade 64 is moved in the vertical direction by the lifting mechanism.

As shown in FIG. 9 (A) and FIG. 9 (B), when forming the groove which is the starting point of division, for example, the cutting blade 64 described above is rotated and cut into the remaining peripheral area 11d (that is, the reinforcing portion). Thereby, the groove 11e which becomes a starting point of division can be formed in a reinforcement part. The groove 11e is preferably formed along, for example, a predetermined division line 13. By forming such a groove 11e, it becomes possible to divide the wafer region 11c of the workpiece 11 together with the remaining peripheral region 11d.

In addition, the structures, methods, and the like of the above embodiments and modifications can be appropriately modified and implemented without departing from the scope of the object of the present invention.

2‧‧‧laser processing equipment

4‧‧‧ abutment

6, 54‧‧‧ Work clamp table (holding table)

6a, 54a‧‧‧ holding surface

6b, 54b ‧‧‧ Attraction Road

8‧‧‧ horizontal movement mechanism

10‧‧‧X-axis guide

11‧‧‧ Object (workpiece)

11a‧‧‧front

11b‧‧‧Back

11c‧‧‧Chip area

11d‧‧‧External area

12‧‧‧X-axis moving table

13‧‧‧ divided scheduled line (cutting line)

14‧‧‧X-axis ball screw

15‧‧‧area

16‧‧‧X-axis pulse motor

17‧‧‧laser beam

18‧‧‧X axis ruler

19, 19a, 19b, 19c, 19d

20‧‧‧Y-axis guide

21‧‧‧fluid

22‧‧‧Y-axis moving table

23‧‧‧ Rift

24‧‧‧Y-axis ball screw

25‧‧‧Chip

26‧‧‧Y-axis pulse motor

28‧‧‧Y-axis ruler

30‧‧‧Support

32, 56‧‧‧ valve

34, 58‧‧‧ Attraction sources

36‧‧‧ support structure

38‧‧‧ support arm

40‧‧‧laser irradiation unit

42‧‧‧ Camera

44‧‧‧ Sheet (Porous Sheet)

44a‧‧‧upper surface

52‧‧‧ Split device

54c‧‧‧heater (heating unit)

60‧‧‧Nozzle (cooling unit)

62‧‧‧Cutting Unit

64‧‧‧ cutting blade

FIG. 1 is a perspective view schematically showing a configuration 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 first 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 a state of a processed object after the modified layer is formed, and FIG. 5 (B) is a sectional view schematically showing a state of the modified layer.

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

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

FIG. 8 is a cross-sectional view for explaining a holding procedure according to a modification.

FIG. 9 (A) is a cross-sectional view for explaining a dividing step of a modified example, and FIG. 9 (B) is a plan view schematically showing a state of a workpiece before dividing a wafer region in a dividing step of a modified example .

Claims (3)

A method of manufacturing a wafer is to manufacture a plurality of wafers from a processed object, the processed object having a wafer region that is divided into a plurality of regions to be the wafer by a plurality of intersecting predetermined division line regions, and In the remaining area of the periphery, the method for manufacturing the wafer includes: A holding step to keep the worktable directly holding the workpiece; The first laser processing step is to position the condensing point of the laser beam having a wavelength penetrating to the workpiece after the holding step is performed on the inside of the workpiece held on the holding table. To irradiate the laser beam only along the predetermined division line to the wafer region of the workpiece, and form a first modified layer along the predetermined division line of the wafer region, and set the remaining peripheral region to A reinforcing portion without the first modified layer; The second laser processing step is to position the condensing point of the laser beam having a wavelength penetrating to the workpiece after the holding step is performed on the inside of the workpiece held on the holding table. Way to irradiate the laser beam along a boundary between the wafer region and the remaining area around the periphery, and form a second modified layer along the boundary; A carrying-out step, after performing the first laser processing step and the second laser processing step, unloading the workpiece from the holding table; and Dividing step, after carrying out the unloading step, applying force to the workpiece to divide the workpiece into the wafers, In the dividing step, the force is applied by heating and cooling to divide the workpiece into the wafers. For example, the method for manufacturing a wafer according to claim 1 further includes a step of removing the reinforcing portion. The step of removing the reinforcing portion is performed after the first laser processing step and the second laser processing step and before the division step. This reinforcing portion is removed. If the method for manufacturing a wafer according to claim 1 or 2, wherein the upper surface of the holding table is made of a soft material, In this holding step, the front side of the workpiece is held by the soft material.