TWI765027B - Method for manufacturing wafers - Google Patents

Abstract

[Subject] To provide a method for producing a wafer capable of producing a plurality of wafers by dividing a plate-shaped workpiece without using an expansion sheet. [Solution] Including: a laser processing step of irradiating only the wafer area along the planned dividing line with a laser beam having a wavelength that is penetrating to the silicon wafer, and forming a modified layer along the planned dividing line of the wafer area , and the remaining area of the outer periphery is set as a reinforcing part without a modified layer; and the dividing step is to impart a force to the silicon wafer to divide the silicon wafer into individual chips. In the dividing step, by A single cooling or heating imparts force to divide the silicon wafer into individual chips.

Description

Method for manufacturing wafers

FIELD OF THE INVENTION The present invention relates to a method for producing a wafer for producing a plurality of wafers by dividing a plate-shaped workpiece.

Background of the Invention In order to divide a plate-shaped workpiece (workpiece) represented by a wafer into a plurality of wafers, the following method is known: condensing a penetrating laser beam inside the workpiece, To form a modified layer (modified region) modified by multiphoton absorption (see, for example, Patent Document 1). Since the modified layer is weaker than other regions, by forming the modified layer along the planned dividing line (cutting line) and then applying a force to the workpiece, the modified 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 workpiece on which the modified layer is formed, for example, a method of adhering a stretchable expansion sheet (expanding tape) to the workpiece for expansion can be employed (for example, refer to Patent Document 2). In this method, generally, before irradiating a laser beam to form a modified layer on the workpiece, the expansion sheet is attached to the workpiece, and after the modification layer is formed, the expansion sheet is expanded to expand the workpiece. Divided into a plurality of wafers. Prior Art Documents Patent Documents

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 expansion sheet after use cannot be reused, it is easy to increase the cost required for the manufacture of 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 of manufacturing the wafer also increases.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a wafer manufacturing method capable of dividing a plate-shaped workpiece to manufacture a plurality of wafers without using an expansion sheet. means of solving problems

According to an aspect of the present invention, there is provided a method for manufacturing a chip, wherein a plurality of chips are produced from a silicon wafer, wherein the silicon wafer has a plurality of predetermined lines divided by intersecting a plurality of predetermined lines to become the chip. The chip area of the area, and the peripheral remaining area surrounding the chip area, the manufacturing method of the chip includes: a holding step to directly hold a silicon wafer with a holding table; a laser processing step, after the holding step is performed, to The way that the condensing point of the laser beam of the wavelength having penetrating wafer is positioned inside the silicon wafer that has been held on the holding table, so that the laser beam is directed only to the silicon wafer along the predetermined dividing line. irradiating the wafer region of the wafer region to form a modified layer along the planned dividing line of the wafer region, and the remaining outer peripheral region is set as a reinforcing part without a modified layer formed; in the carrying out step, the laser processing step is carried out Then, the silicon wafer is carried out from the holding table; and a dividing step, after the carrying out step is carried out, a force is applied to the silicon wafer to divide the silicon wafer into the individual chips, and in the dividing step, the The force is imparted by one cooling or heating to divide the silicon wafer into the individual chips.

In one aspect of the present invention, a reinforcing portion removing step may be further provided, and the reinforcing portion removing step is to remove the reinforcing portion after the laser processing step is performed and before the dividing step is performed. Furthermore, in one aspect of the present invention, the upper surface of the holding table may be formed of a soft material, and in the holding step, the front side of the silicon wafer is held by the soft material . Invention effect

In the method for manufacturing a wafer according to one aspect of the present invention, since the silicon wafer is directly held by the holding table, only the chip region of the silicon wafer is irradiated with a laser beam to form a modification along the dividing line. After that, a force is applied by cooling or heating once to divide the silicon wafer into individual chips, so there is no need to use an extension sheet in order to apply force to the silicon wafer to divide into individual chips. As described above, according to the method for manufacturing a wafer of one aspect of the present invention, a silicon wafer, which is a plate-shaped workpiece to be processed, can be divided without using an expansion sheet to manufacture a plurality of wafers.

In addition, in the method for manufacturing a wafer according to an aspect of the present invention, only the wafer region of the silicon wafer is irradiated with a laser beam to form a modified layer along the line to divide, and the remaining peripheral region is left untouched. Since the reinforcing portion of the modified layer is formed, the wafer region can be reinforced by the reinforcing portion. According to this, the silicon wafer is not divided into individual chips due to the force applied during conveyance or the like, and the silicon wafer cannot be appropriately conveyed.

MODE FOR CARRYING OUT THE INVENTION An embodiment of one aspect of the present invention will be described with reference to the drawings. The wafer manufacturing method of the present embodiment includes a holding step (refer to FIG. 3(A)), a laser processing step (refer to FIGS. 3(B), 4(A), and 4(B)), a carry-out step, and a reinforcing portion A removal step (refer to FIG. 5(A) and FIG. 5(B) ) and a division step (refer to FIG. 6 ).

In the holding step, the workpiece (workpiece) is directly held by the work chuck (holding table), and the workpiece has a wafer area divided into a plurality of areas by the predetermined dividing line, and an outer peripheral remainder surrounding the wafer area. area. In the laser processing step, a laser beam having a wavelength that is penetrating to the workpiece is irradiated to form a modified layer (modified region) along the dividing line in the wafer region, and the remaining peripheral region is set It is a reinforcement part in which a modified layer is not formed.

In the unloading step, the workpiece is unloaded from the holding table. In the step of removing the reinforcing portion, the reinforcing portion is removed from the workpiece. In the dividing step, the workpiece is divided into a plurality of wafers by applying force by one cooling or heating. Hereinafter, the manufacturing method of the wafer 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 semiconductors such as silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), etc., sapphire ( Dielectrics (insulators) such as Al ₂ O ₃ ), soda glass, borosilicate glass, quartz glass, etc., or ferroelectrics (ferroelectrics such as lithium tantalate (LiTa ₃ ), lithium niobate (LiNb ₃ ), etc. A disc-shaped wafer (substrate) formed from crystals).

The front surface 11a side of the workpiece 11 is divided into a plurality of regions 15 to be wafers by a plurality of planned dividing lines (dicing lines) 13 that intersect. Hereinafter, a substantially circular region including all of the regions 15 serving as wafers is referred to as a wafer region 11c, and an annular region surrounding the wafer region 11c is referred to as an outer peripheral remaining region 11d.

In each area 15 in the wafer area 11c, an IC (Integrated Circuit), a MEMS (Micro Electro Mechanical Systems), and an LED (Light Emitting Diode) can be formed according to needs. ), LD (Laser Diode, Laser Diode), Photodiode (Photodiode), SAW (Surface Acoustic Wave, Surface Acoustic Wave) filter, BAW (Bulk Acoustic Wave) filter and other devices.

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

When the workpiece 11 is a silicon carbide substrate, for example, a wafer that functions as a power device or the like can be obtained. When the workpiece 11 is a sapphire substrate, for example, a wafer that functions as a light-emitting element or the like can be obtained. 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 a cover member (cover glass), for example, can be obtained.

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

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

As shown in FIG. 2, the laser processing apparatus 2 is provided with the base 4 which mounts each component. A horizontal moving mechanism 8 is provided on the upper surface of the base 4, and the horizontal moving mechanism 8 makes the work clamp table (holding table) 6 for sucking and holding the workpiece 11 in the X-axis direction (processing feed direction) and Move in the Y-axis direction (indexing 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.

On the X-axis guide rail 10, an X-axis moving stage 12 is slidably mounted. 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 rail 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 . By rotating the X-axis ball screw 14 by the X-axis pulse motor 16 , the X-axis moving stage 12 can be moved in the X-axis direction along the X-axis guide rail 10 . An X-axis ruler 18 for detecting the position of the X-axis moving stage 12 in the X-axis direction is provided at a position adjacent to the X-axis guide rail 10 .

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 . On the Y-axis guide rail 20, a Y-axis moving stage 22 is slidably mounted. 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 to the nut portion.

A Y-axis pulse motor 26 is connected to one end of each Y-axis ball screw 24 . By rotating the Y-axis ball screw 24 by the Y-axis pulse motor 26 , the Y-axis moving stage 22 can be moved in the Y-axis direction along the Y-axis guide rail 20 . A Y-axis ruler 28 for detecting the position of the Y-axis moving stage 22 in the Y-axis direction is provided at a position adjacent to the Y-axis guide rail 20 .

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 table 6 is a holding surface 6a that attracts and holds 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. Among them, 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 a suction source 34 (see FIG. 3(A) and the like) through a suction passage 6b (see FIG. 3(A) and the like) or a valve 32 (see FIG. 3(A) and the like) formed inside the table 6 . 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 rotary 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 , and the laser irradiation unit 40 generates pulsed oscillation to the workpiece 11 . The laser beam 17 (refer to FIG. 3(B) ) having a penetrating wavelength (wavelength that is difficult to be absorbed) is irradiated on the workpiece 11 on the work table 6 .

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 . An image formed by photographing the object to be processed 11 or the like with the camera 42 is used, for example, when adjusting the positions of the object to be processed 11 and the laser irradiation unit 40 or the like.

The components of the work clamp table 6, the horizontal movement mechanism 8, the laser irradiation unit 40, the camera 42, etc. are connected to a control unit (not shown). The control unit controls each component so as to process the workpiece 11 appropriately.

FIG. 3(A) is a cross-sectional view for explaining the holding step. In addition, in FIG. 3(A), some constituent elements are shown as 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 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 to-be-processed object 11 can be attracted|sucked and hold|maintained by the holding table 6 in the state which the front surface 11a side is exposed upwards. In addition, in this embodiment, as shown in FIG.3(A), the back surface 11b side of the to-be-processed object 11 is hold|maintained by the table 6 directly. That is, in this embodiment, it is not necessary to attach the expansion sheet to the workpiece 11 .

The holding step is followed by a laser processing step of irradiating a laser beam 17 having a wavelength that is transparent to the workpiece 11 to form a modified layer along the dividing line 13 . 3(B) is a cross-sectional view for explaining the laser processing step, FIG. 4(A) is a plan view schematically showing the state of the workpiece 11 after the laser processing step, and FIG. 4(B) is a schematic diagram A cross-sectional view showing the state of the workpiece 11 after the laser processing step. In addition, in FIG. 3(B), some constituent elements are shown as functional blocks.

In the laser processing step, first, the 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 stage 6 is moved, and the position of the laser irradiation unit 40 is aligned on the extension line of the target dividing line 13 . Then, as shown in FIG. 3(B) , the table 6 is moved in the X-axis direction (ie, the extending direction of the line to divide the object 13 ).

Then, at the time point when the laser irradiation unit 40 has reached directly above one side of the boundary between the wafer region 11c and the outer peripheral remaining region 11d existing at two places on the intended dividing line 13 to be targeted, the laser irradiation is performed from the laser The unit 40 starts the irradiation of the laser beam 17 . In this embodiment, as shown in FIG.3(B), the laser beam 17 is irradiated toward the front surface 11a of the to-be-processed object 11 from the laser irradiation unit 40 arrange|positioned above the to-be-processed object 11.

The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 reaches directly above the other side of the boundary between the wafer region 11c and the peripheral remaining region 11d at two locations on the intended dividing line 13 to be the target. That is, here, the laser beam 17 is irradiated only in the wafer region 11c along the intended dividing line 13 of the object.

Moreover, this laser beam 17 is irradiated so that a condensing point may be located in the inside of the to-be-processed object 11 from the position of the predetermined depth from the front surface 11a (or the back surface 11b). In this way, by condensing the laser beam 17 having a wavelength that is penetrating to the workpiece 11 inside the workpiece 11, the laser beam 17 of the workpiece 11 is absorbed by multiphoton at the condensing point and its vicinity. A part is modified, and a modified layer (modified region) 19 serving as the starting point of division can be formed. In the present embodiment, since the laser beam 17 is irradiated only in the wafer area 11c along the target dividing line 13, the modification can be formed only in the wafer area 11c along the target dividing line 13 Layer 19.

After the modified layer 19 is formed at a predetermined depth along the target dividing line 13, the modified layer 19 is formed at other depths along the target dividing line 13 by the same process. Specifically, as shown in FIG. 4(B), for example, the modified layers 19 (the first modified layers 19a, 19a, The second modified layer 19b and the third modified layer 19c).

There is no particular limitation on the number or position of the modified layers 19 formed along one planned dividing line 13 . For example, the number of modified layers 19 formed along one planned dividing line 13 may be one. In addition, it is preferable that the reforming layer 19 is formed under conditions such that the cracks reach the front surface 11a (or the back surface 11b). Of course, the modified layer 19 may be formed on the condition that the cracks reach both the front surface 11a and the back surface 11b. Thereby, it becomes possible to divide the workpiece 11 more appropriately.

When the workpiece 11 is a silicon wafer, the modified layer 19 is formed under the following conditions, for example. Object to be processed: Silicon Wafer Laser beam wavelength: 1340nm Laser beam repetition rate: 90kHz Laser beam output: 0.1W~2W Work chuck moving speed (processing feed speed): 180mm/s~1000mm /s, the representative is 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. Object to be processed: GaAs substrate, Indium Phosphide substrate Laser beam wavelength: 1064nm Laser beam repetition rate: 20kHz Laser beam output: 0.1W~2W The moving speed of the work table (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. Object to be processed: Sapphire substrate Laser beam wavelength: 1045nm Laser beam repetition frequency: 100kHz Laser beam output: 0.1W~2W Work chuck moving speed (processing feed speed): 400mm/s~800mm/ s, the representative is 500mm/s

When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal 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 . Object to be processed: Lithium tantalate substrate, lithium niobate substrate Laser beam wavelength: 532nm Laser beam repetition frequency: 15kHz Laser beam output: 0.02W~0.2W The moving speed of the work table (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. Objects to be processed: soda glass substrate, borosilicate glass substrate, quartz glass substrate Laser beam wavelength: 532nm Laser beam repetition frequency: 50kHz Laser beam output: 0.1W~2W Working speed Speed): 300mm/s~600mm/s, the representative is 400mm/s

When the workpiece 11 is a gallium nitride substrate, the modified layer 19 is formed under the following conditions, for example. Object to be processed: GaN substrate Laser beam wavelength: 532nm Laser beam repetition rate: 25kHz Laser beam output: 0.02W~0.2W Working chuck moving speed (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~0.2W, typically 0.1W The moving speed of the work clamp (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

After the required number of modified layers 19 are formed along the target dividing line 13 , the above-described operation is repeated to form the modified layers 19 along all other planned dividing lines 13 . As shown in FIG. 4(A) , when the modified layer 19 is formed along all the lines 13 to be divided, the laser processing step is completed.

In the present embodiment, since the modified layer 19 is formed only in the wafer region 11c along the planned dividing line 13, and the modified layer 19 is not formed in the outer peripheral region 11d, the outer peripheral region 11d can be used to form the modified layer 19. The strength of the workpiece 11 is maintained. This prevents the workpiece 11 from being divided into individual wafers due to a force applied during conveyance or the like. In this way, the remaining peripheral region 11d after the laser processing step functions as a reinforcing portion for reinforcing the wafer region 11 on which the modified layer 19 is formed.

Furthermore, in the present embodiment, since the modified layer 19 is not formed in the remaining outer peripheral region 11d, the workpiece 11 is completely removed even if the crack extending from the modified layer 19 reaches both the front surface 11a and the back surface 11b, for example. Even in the state of being divided, the wafers are not dropped or scattered. Generally, when the modified layer 19 is formed on the workpiece 11 , the workpiece 11 expands in the vicinity of the modified layer 19 . In the present embodiment, the expansion force generated by the formation of the reformed layer 19 is caused to act inwardly by the annular residual region 11d functioning as a reinforcing portion, thereby suppressing each wafer and preventing the fall off, disperse.

After the laser processing step, a carry-out step of carrying out the workpiece 11 from the table 6 is performed. Specifically, for example, after sucking the entire front surface 11a of the workpiece 11 by a transfer unit (not shown) capable of sucking and holding the entire front surface 11a (or the rear surface 11b) of the workpiece 11, the valve 32 is opened to block The negative pressure of the suction source 34 is interrupted, and the workpiece 11 is carried out. Furthermore, in the present embodiment, as described above, since the remaining outer peripheral region 11d functions as a reinforcing portion, there is no case where the workpiece 11 is damaged due to a force applied during conveyance or the like. Since the wafers are divided into individual wafers, the workpiece 11 cannot be appropriately transported.

After the unloading step, a reinforcing portion removing step of removing the reinforcing portion from the workpiece 11 is performed. 5(A) and 5(B) are cross-sectional views for explaining the step of removing the reinforcing portion. In addition, in FIG.5(A) and FIG.5(B), some constituent elements are shown as functional blocks. The reinforcement part removal process is performed using the division|segmentation apparatus 52 shown to FIG.5(A) and FIG.5(B), for example.

The dividing device 52 includes a table 54 for sucking and holding the workpiece 11 . A part of the upper surface of the table 54 serves as a holding surface 54a for attracting and holding the wafer region 11c of the workpiece 11 . The holding surface 54a is connected to the suction source 58 through a suction passage 54b formed in the table 54, a valve 56, or the like.

In addition, the other part of the upper surface of the table 54 is opened with one end of a suction path 54c for sucking and holding the remaining outer peripheral region 11d (ie, reinforcing portion) of the workpiece 11 . The other end side of the suction passage 54c is connected to the suction source 58 through the valve 60 or the like. The table 54 is connected to a rotational drive source (not shown) such as a motor, and rotates around a rotational axis substantially parallel to the vertical direction.

A cutting unit 62 is arranged above the work clamp table 54 . The cutting unit 62 is provided with the main shaft 64 which is a rotation axis which becomes substantially parallel to the holding surface 54a. On one end side of the main shaft 64, an annular cutter 66 is attached, and the annular cutter 66 is configured by dispersing abrasive grains in a binder.

A rotary drive source (not shown) such as a motor is connected to the other end side of the main shaft 64, and the cutter 66 mounted on one end side of the main shaft 64 is driven by the force transmitted from the rotary drive source. rotate. The cutting unit 62 is supported by, for example, a lift mechanism (not shown), and the cutting blade 66 is moved in the vertical direction by the lift mechanism.

Furthermore, a relief groove (not shown) for a dicing blade is formed on the upper surface of the work chuck 54 at a position corresponding to the boundary between the wafer region 11c of the workpiece 11 and the remaining peripheral region 11d. The relief groove is for preventing contact with the cutting blade 66 .

In the step of removing the reinforcing portion, first, the back surface 11 b of the workpiece 11 is brought into contact with the holding surface 54 a of the table 54 . Then, the valves 56 and 60 are opened, and the negative pressure of the suction source 58 is applied to the holding surface 54a and the like. Thereby, the workpiece 11 is sucked and held on the table 54 in a state where the front surface 11a side is exposed upward. In addition, in this embodiment, as shown in FIG. 5(A), the back surface 11b side of the to-be-processed object 11 is directly held by the work chuck 54. As shown in FIG. That is, here, too, it is not necessary to attach the expansion sheet to the workpiece 11 .

Next, the dicing blade 66 is rotated to cut into the boundary between the wafer region 11c of the workpiece 11 and the remaining peripheral region 11d. Together, as shown in FIG. 5(A) , the table 54 is rotated about a rotation axis substantially parallel to the vertical direction. Thereby, the workpiece 11 can be cut along the boundary between the wafer region 11c and the peripheral remaining region 11d.

After that, the valve 60 is closed to shut off the negative pressure of the suction source 58 on the remaining peripheral region 11 d of the workpiece 11 . Then, as shown in FIG. 5(B) , the remaining peripheral region 11 d is removed from the table 54 . As a result, only the wafer region 11 c of the workpiece 11 is left on the table 54 .

After the step of removing the reinforcement portion, a step of dividing the workpiece 11 into individual wafers is performed. Specifically, for example, a large temperature difference is formed inside the workpiece 11 (between the front surface 11 a and the back surface 11 b ), and a force is applied to the workpiece 11 by thermal shock (thermal shock). to split. FIG. 6 is a cross-sectional view for explaining the dividing step. In addition, in FIG. 6, some constituent elements are shown as functional blocks.

The segmentation step is continued using the segmentation device 52 . As shown in FIG. 6 , the dividing device 52 further includes a spray nozzle (temperature difference forming means) 68 arranged above the work chuck 54 . In the dividing step of the present embodiment, the cooling fluid 21 is sprayed from the spray nozzle 68 to the front surface 11a of the workpiece 11 to form a temperature difference required for the generation of thermal shock. The temperature difference required for the generation of thermal shock can also be formed by spraying the fluid 21 for additional heat.

As the cooling fluid 21, for example, a low-temperature liquid such as liquid nitrogen that can further deprive heat by vaporization is preferably used. Thereby, the front surface 11a side of the to-be-processed object 11 can be cooled rapidly, and it becomes easy to form a required temperature difference. Here, the required temperature difference refers to the temperature difference for obtaining a thermal shock exceeding the required stress in order to break the workpiece 11 along the modified layer 19 . This temperature difference is determined according to, for example, the material and thickness of the workpiece 11 , the state of the modified layer 19 , and the like.

However, the type, flow rate, and the like of the fluid 21 are not particularly limited. Gases such as sufficiently cooled air, or liquids such as water can also be used. Furthermore, when a liquid is used as the fluid 21, it is preferable to pre-cool the liquid to a low temperature (eg, a temperature about 0.1°C to 10°C higher than the freezing point) that does not freeze.

When the workpiece 11 is cooled to form a sufficient temperature difference, the cracks 23 can be extended from the modified layer 19 by thermal shock, and the workpiece 11 can be divided into a plurality of wafers 25 along the dividing line 13 . In this way, in the present embodiment, the workpiece 11 can be divided into the individual wafers 25 by applying a necessary force by one cooling. Furthermore, in the present embodiment, although the thermal shock is generated by rapidly cooling the workpiece 11 , thermal shock may be generated by rapidly heating the workpiece 11 .

As described above, in the wafer manufacturing method of the present embodiment, only the wafer region 11c of the workpiece 11 is irradiated in a state where the workpiece (workpiece) 11 is directly held by the work chuck (holding table) 6 The laser beam 17 is used to form the modified layer 19 along the line 13 to be divided, and after that, a force is applied by the primary cooling to divide the workpiece 11 into individual wafers 25. Therefore, it is not necessary to The object 11 applies a force to divide the wafers 25 into individual wafers 25 using the expansion sheet. As described above, according to the wafer manufacturing method of the present embodiment, a plurality of wafers 25 can be manufactured by dividing the plate-shaped workpiece 11, that is, a silicon wafer, without using an expansion sheet.

Further, in the wafer manufacturing method of the present embodiment, the modified layer 19 along the line 13 to be divided is formed by irradiating only the wafer region 11c of the workpiece 11 with the laser beam 17, and the remaining peripheral region 11d is provided Since it is a reinforcement part in which the modified layer 19 is not formed, the wafer region 11c can be reinforced by this reinforcement part. Accordingly, there is no possibility that the workpiece 11 cannot be properly transported due to the division of the workpiece 11 into the individual wafers 25 due to a force applied during transportation or the like.

In addition, this invention is not limited by the description of the said embodiment etc., It can implement with various changes. For example, in the holding step of the above-described embodiment, the table 6 directly holds the back surface 11b of the workpiece 11 and irradiates the laser beam 17 from the front 11a side, but the table 6 directly holds the workpiece 11. The front surface 11a side of the object 11 may be irradiated with the laser beam 17 from the back surface 11b side.

FIG. 7 is a cross-sectional view for explaining a holding step in a modification. In the holding step of this modification, as shown in FIG. 7, for example, a porous sheet (porous sheet) formed of a soft material typified by a resin such as polyethylene or epoxy may also be used. ) 44 to constitute the work clamp table (holding table) 6 on the upper surface.

On the table 6, the upper surface 44a of the sheet 44 is formed so as to attract and hold the front surface 11a side of the workpiece 11. Thereby, breakage of the device etc. formed on the front surface 11a side can be prevented. The sheet material 44 is a part of the work jig 6 and can be reused together with the main body of the work jig 6 and the like.

However, the upper surface of the table 6 does not necessarily have to be formed of the above-mentioned porous sheet 44, as long as the upper surface of the work table 6 is not damaged at least to the extent that the devices formed on the front surface 11a side of the workpiece 11 are not damaged. It can be made of soft material. Furthermore, it is preferable that the sheet 44 is configured to be detachable from the main body of the table 6, and can be replaced in the case of being damaged or the like.

Moreover, in the said embodiment, although the reinforcement part removal process is performed after the carry-out process and before the division process, for example, the reinforcement part removal process may be performed after the laser processing process and before the carry-out process. Furthermore, in the case where the step of removing the reinforcement portion is performed after the step of unloading and before the step of dividing, since it is not necessary to convey the workpiece 11 after the step of removing the reinforcement portion, it is easy to avoid a defect that the workpiece 11 cannot be appropriately conveyed. situation.

Moreover, the reinforcement part removal process may be abbreviate|omitted. In this case, it is preferable to adjust the range in which the modified layer 19 is formed in the laser processing step so that, for example, the width of the reinforcing portion is about 2 mm to 3 mm from the outer peripheral edge of the workpiece 11 . Moreover, for example, before dividing the wafer region 11c in the dividing step, a groove that becomes a starting point of dividing may be formed in the reinforcing portion. FIG. 8(A) is a cross-sectional view for explaining the division step of the modification example, and FIG. 8(B) schematically shows the state of the workpiece 11 before the wafer region 11 c is divided in the division step of the modification example. floor plan.

In the dividing step of the modification, as shown in FIGS. 8(A) and 8(B) , the cutting blade 66 is cut into the remaining peripheral region 11d (ie, the reinforcing portion) to form a groove 11e serving as a starting point for dividing. Preferably, the groove 11e is formed along the line 13 to be divided, for example. By forming such a groove 11e, it becomes possible to divide the workpiece 11 together with the remaining outer peripheral region 11d by thermal shock. In addition, in the dividing step of the modification, the suction path 54c of the table 54, the valve 60, and the like can be omitted.

In addition, the configurations, methods, and the like of the above-described embodiments and modified examples can be appropriately changed and implemented without departing from the scope of the present invention.

11‧‧‧Workpiece (workpiece) 11a‧‧‧Front surface 11b‧‧‧Back surface 11c‧‧‧Wafer area 11d‧‧‧Outer peripheral area 13‧‧‧Planning line for dividing (dicing line) 15‧‧‧Area 17 ‧‧‧Laser beam 19‧‧‧modified layer (modified region) 19a‧‧‧first modified layer 19b‧‧‧second modified layer 19c‧‧‧third modified layer 21‧‧‧fluid 23‧‧‧Crack 25‧‧‧Wafer 2‧‧‧Laser processing device 4‧‧‧Base 6, 54‧‧‧Working table (holding table) 6a, 54a‧‧‧Retaining surface 6b, 54b, 54c ‧‧‧Suction path 8‧‧‧Horizontal moving mechanism 10‧‧‧X axis guide rail 12‧‧‧X axis moving table 14‧‧‧X axis ball screw 16‧‧‧X axis pulse motor 18‧‧‧X axis ruler Gauge 20‧‧‧Y axis guide 22‧‧‧Y axis moving table 24‧‧‧Y axis ball screw 26‧‧‧Y axis pulse motor 28‧‧‧Y axis ruler 30‧‧‧Support table 32, 56, 60‧‧‧Valve 34, 58‧‧‧Suction source 36‧‧‧Support structure 38‧‧‧Support arm 40‧‧‧Laser irradiation unit 42‧‧‧Camera 44‧‧‧Sheet (porous sheet) 44a ‧‧‧Top surface 52‧‧‧Separation device 62‧‧‧Cutting unit 64‧‧‧Spindle 66‧‧‧Cutting blade 68‧‧‧Jet nozzle (temperature difference forming unit) X, Y, Z‧‧‧ directions

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 laser processing step. 4(A) is a plan view schematically showing the state of the workpiece after the laser processing step, and FIG. 4(B) is a cross-sectional view schematically showing the state of the workpiece after the laser processing step. 5(A) and 5(B) are cross-sectional views for explaining the step of removing the reinforcing portion. FIG. 6 is a cross-sectional view for explaining the dividing step. FIG. 7 is a cross-sectional view for explaining a holding step of a modification. 8(A) is a cross-sectional view for explaining the division step of the modification, and FIG. 8(B) is a plan view schematically showing the state of the workpiece before the wafer region is divided in the division step of the modification.

11‧‧‧Workpiece (workpiece)

11a‧‧‧Front

11b‧‧‧Back

11c‧‧‧Chip area

21‧‧‧Fluid

23‧‧‧Fissure

25‧‧‧Chip

52‧‧‧Separation device

54‧‧‧Working table (holding table)

54a‧‧‧Maintaining surface

54b, 54c‧‧‧Attraction Road

56, 60‧‧‧valve

58‧‧‧Source of attraction

68‧‧‧Jet nozzle (temperature difference forming unit)

Claims (2)

A method of manufacturing a wafer, which is to manufacture a plurality of wafers from a plate-shaped workpiece, wherein the plate-shaped workpiece has a wafer region in which a plurality of regions to be the wafer are demarcated by intersecting a plurality of predetermined dividing lines , and a peripheral remaining area surrounding the wafer area, the wafer manufacturing method is characterized in that: a holding step is provided to directly hold the workpiece with a holding table; a laser processing step, after the holding step is implemented, to The condensing point of the laser beam of the wavelength having penetrability to the workpiece is positioned inside the workpiece held on the holding table, so that the laser beam is directed only to the workpiece along the predetermined dividing line. irradiating the wafer region of the wafer region to form a modified layer along the planned dividing line of the wafer region, and the remaining outer peripheral region is set as a reinforcing part without a modified layer formed; in the carrying out step, the laser processing step is performed Then, the workpiece is carried out from the holding table; the reinforcement part removing step, after the carrying out step is carried out, the workpiece is held by the work chuck and the reinforcement part is removed; and the division step, after the reinforcement part removal step is carried out. , to impart a force to the workpiece held by the work chuck, so as to divide the workpiece into the wafers one by one, in the splitting step, the force is imparted by one cooling or heating, to divide the workpiece into individual wafers. A method for manufacturing a wafer as claimed in claim 1, wherein the guarantee The upper surface of the holding table is made of a soft material, and in the holding step, the front side of the workpiece is held with the soft material.

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