TW202109640A - Manufacturing method of multiple device chips for preventing defects at corners of device chips - Google Patents

Abstract

The invention prevents defects at corners of device chips while grinding the workpiece for thinning and dividing workpiece. As the solution, the invention includes a hole forming step for irradiating a first laser beam with a wavelength to be absorbed by the workpiece onto the surface side of the workpiece and forming holes deeper than the finished thickness of each device chip at the intersection of the plurality of crossed predetermined scribe lines; a surface protection step for coating the surface side of the workpiece with a protective member; an internal processing step for positioning the focus point of a second laser beam with a wavelength for penetrating the workpiece inside the workpiece, and then irradiating the second laser beam from the back side of the workpiece along each predetermined scribe line to form a region with lower intensity in the interior of the workpiece; and, a back side grinding step for dividing the workpiece into a plurality of device chips while grinding the back side of the workpiece until the work piece reached the finished thickness.

Description

Manufacturing method of plural device chips

The present invention relates to a method for manufacturing a plurality of device chips by dividing a workpiece along a plurality of predetermined dividing lines.

Manufacturing IC (Integrated Circuit), LSI (Large Scale In the process of device wafers with functional elements such as integration), first, on the surface side of a substantially disc-shaped workpiece formed of semiconductors such as silicon, a plurality of planned division lines are set in a grid shape. Next, after each area divided by a plurality of planned dividing lines to form functional elements such as ICs and LSIs, the workpiece is divided along the planned dividing lines.

In order to divide the workpiece along each planned dividing line, for example, first, along each planned dividing line, a modified layer in the area of reduced mechanical strength is formed inside the workpiece along each planned dividing line (for example, refer to Patent Document 1 ). In order to form the modified layer, a laser processing device is used.

The laser processing device has a chuck for holding the processed object. Above the chuck, a laser beam irradiation unit that can irradiate a pulsed laser beam with a wavelength that passes through the workpiece is provided.

Position the condensing point of the laser beam irradiated from the laser beam irradiation unit inside the object to be processed, move the chuck in a specific direction, and move the chuck in a specific direction to the inside of the object to be processed along the predetermined dividing line Form a modified layer.

After laser processing, use a grinding device to grind the back side of the workpiece. As a result, the object to be processed is thinned while receiving an external force, and the modified layer is used as the starting point of fracture to be divided along each planned division line. In this way, the workpiece is divided into plural device wafers by external force during polishing. [Prior Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2006-12902

[The problem to be solved by the invention]

However, when using a grinding device to polish the back side of the workpiece, the intersection where the two planned dividing lines intersect is likely to be chipped due to the friction between the corners of the device wafer. In addition, the defects generated in the corners may progress to the field of forming functional elements when the device chip is subjected to external force.

In view of the related problems, the present invention aims to prevent defects in the corners of the device wafer when the workpiece is polished and thinned to divide the workpiece. [Means to solve the problem]

According to one aspect of the present invention, there is provided a workpiece provided with a device for forming a plurality of areas divided by a plurality of planned division lines set in a grid on the surface side, and divided into individual parts along each planned division line In the method of manufacturing a plurality of device wafers from the workpiece, the device wafer is irradiated with a first laser beam having a wavelength absorbed by the workpiece from the outside of the workpiece to the surface side. A hole with a deeper depth corresponding to the finished thickness of each device chip, a hole forming step formed at the intersection of the plurality of predetermined dividing lines, and a surface protection step of covering the surface side of the workpiece with a protective member, and Position the condensing point of the second laser beam having a wavelength that passes through the workpiece in a state where the depth corresponding to the finished thickness is located inside the workpiece on the back side of the workpiece, along Each planned division line irradiates the second laser beam from the back side, and forms a region with a lower intensity than the region where the second laser beam is not irradiated, and is formed in the internal processing step of the workpiece, The method of manufacturing plural device wafers by grinding the back side of the workpiece into plural device wafers while grinding the back side of the workpiece before the workpiece becomes the finished thickness.

In the hole forming step, as the hole, a non-through hole that does not penetrate from the surface to the back surface can be formed.

Furthermore, in the hole forming step, as the hole, a through hole that penetrates from the surface to the back surface can be formed. [Effects of the invention]

Regarding the method for manufacturing plural device wafers in one aspect of the present invention, the hole forming step is used to form a hole with a depth corresponding to the completed thickness at the intersection. Therefore, the grinding step on the back side can prevent the device wafer The corners of each other rub against each other. Therefore, it is possible to prevent the occurrence of defects in the corners. Moreover, it can prevent the defects generated in the corners and advance to the field of forming functional components.

[For the implementation of the invention]

With reference to the attached drawings, an embodiment of one aspect of the present invention will be described. First, in the first embodiment, the wafer (worked object) 11 to be processed will be described. FIG. 1 is a perspective view of the wafer 11.

The wafer 11 is made of, for example, silicon, and is formed in a disk shape, each having a slightly rounded surface 11a and a back surface 11b. The surface 11a side of the wafer 11 is divided into a plurality of areas through a plurality of planned dividing lines (lines) 13 set in a grid shape that intersect each other.

An IC (Integrated Circuit), LSI (Large Scale Integration), etc. device 15 is formed on the surface 11a side of each area divided by a plurality of planned dividing lines 13.

However, the material, shape, structure, size, etc. of the wafer 11 are not limited. For example, the wafer 11 can be formed of materials other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, and the like. In addition, there are no restrictions on the type, number, shape, structure, size, arrangement, etc. of the device 15.

On the back side 11b of the wafer 11, a round resin tape (not shown) having a larger diameter than the wafer 11 is attached. The resin tape has, for example, a laminated structure of a substrate layer and an adhesive layer (paste layer), and the adhesive layer is attached to the back surface 11b side.

The base layer is formed of, for example, polyolefin (PO). A part or the whole of one surface of the substrate layer is formed on the adhesive layer. The adhesive layer is made of, for example, ultraviolet-curable resin, which is formed of rubber, acrylic, silicone, etc.

However, the resin tape is not limited to the laminated structure of the base layer and the adhesive layer. For example, the resin tape may have only a substrate layer. At this time, on the back surface 11b side of the wafer 11, the resin tape is attached to the wafer 11 via the substrate layer by heat pressing.

A metal ring frame with an opening larger than the diameter of the wafer 11 is attached to the outer periphery of the resin tape. In this way, a wafer unit (not shown) in which the wafer 11 is supported by the ring frame is formed by the resin tape.

By forming the wafer unit, the wafer 11 can be transported while the transport pad (not shown) is in contact with the ring frame without contacting the wafer 11. However, by using a Bernoulli-type transfer pad (not shown) that holds the wafer 11 by non-contact suction, it is not necessary to form a wafer unit when the wafer 11 is transferred. That is, the resin tape may not be attached to the wafer 11.

Next, the method of manufacturing the plural device chips 23 of the first embodiment will be described. In the first embodiment, by dividing the wafer 11 along the planned dividing line 13, a plurality of device wafers 23 each having the devices 15 are manufactured (see FIG. 6). However, FIG. 7 is a flowchart of a method for manufacturing a plurality of device chips 23.

In this embodiment, first, a non-through hole that does not penetrate from the front surface 11a to the back surface 11b is formed at the intersection where the plurality of planned dividing lines 13 intersect (hole forming step (S10)). Fig. 2(A) is a diagram showing the hole forming step (S10).

In order to form the non-through hole 17, for example, the first laser processing device is used. The first laser processing apparatus is provided with a first chuck (not shown) for sucking and holding the back surface 11b side of the wafer 11.

The first chuck is, for example, a porous plate (not shown) having a disk shape. The lower side of the porous plate is connected to a suction source (not shown) such as an ejector through a flow path (not shown) formed inside the first chuck. When the suction source is operated, negative pressure is generated on the upper surface (holding surface) of the porous plate.

Below the first chuck, there is a horizontal moving mechanism (not shown). The horizontal movement mechanism moves the first chuck along the processing conveying direction (X-axis direction) and the classifying conveying direction (Y-axis direction).

Above the first chuck, the first laser beam irradiation unit 10 is provided. The first laser beam irradiation unit 10 has a first laser oscillator (not shown) that generates a pulsed laser beam.

The first laser oscillator includes, for example, Nd:YAG, Nd:YVO ₄ and other laser media suitable for laser oscillation. In the first laser oscillator, the first condenser (not shown) is connected through a specific optical system.

The first concentrator is to condense the laser beam emitted from the first laser oscillator at a specific position below the first concentrator. _{The first laser beam L 1} irradiated downward from the first condenser has a wavelength absorbed by the wafer 11 (for example, 355 nm, 532 nm, or 1064 nm).

In addition, the first laser beam L ₁ is adjusted to have an average output of 0.5 W or more and 50 W or less, a repetition frequency of 1 kHz or more and 200 kHz or less, and a spot diameter of the condensing point of 5 μm or more and 200 μm or less.

However, before processing the wafer 11 using the first laser processing device, a water-soluble resin coating and cleaning device (not shown) is used to coat the surface 11a of the wafer 11 with a water-soluble resin. The water-soluble resin coating and cleaning device is provided with a cleaning pan (not shown) that sucks and holds the back surface 11b side of the wafer 11.

Below the cleaning plate, there is a rotating drive source such as a motor that rotates the cleaning plate. In addition, a resin nozzle (not shown) for spraying water-soluble resin is provided above the cleaning pan. Examples of water-soluble resins include PVA (polyvinyl alcohol), PEG (polyethylene glycol), PEO (polyethylene oxide), and the like.

In addition, in the vicinity of the resin nozzle, on the surface 11a side of the wafer 11, a cleaning nozzle (not shown) for spraying a cleaning solution such as pure water is provided. A drive source (not shown) is connected to the cleaning nozzle. The driving source is to reciprocate the cleaning nozzle on the surface of the cleaning plate in an arc shape.

In the hole forming step (S10), first, the washing pan of the washing device is coated with a water-soluble resin, and the washing pan is rotated, for example, at 2000 rpm while sucking the back surface 11b side of the wafer 11 and holding it.

Then, after positioning the resin nozzle on the surface 11a side of the rotating wafer 11, when the water-soluble resin is sprayed from the resin nozzle, the water-soluble resin is spread to the entire surface 11a side by centrifugal force. In this way, the water-soluble resin is spin-coated on the entire surface 11a side.

After that, the wafer unit is transferred from the water-soluble resin coating and cleaning device to the first laser processing device. In the present embodiment, the wafer 11 is conveyed in a state where the wafer 11 is not in contact with the ring frame. However, when the resin tape is not attached to the wafer 11, after the water-soluble resin is dried, the wafer 11 is transported to the first laser processing device using a Bernoulli-type transport pad.

Then, with the first chuck, the back surface 11b side of the wafer 11 is sucked and held. _{Next, the first laser beam irradiation unit 10 is used to irradiate the first laser beam L 1} from the outside of the wafer 11 to the intersection on the surface 11 a side of the wafer 11.

1 via the laser beam L ₁ of a first condenser 11a, the intersecting portion 11a of the side surface of the wafer 11 to be processed on the surface side of the ablation. As a result, a cylindrical non-through hole 17 having a depth B that is deeper than the depth A of the completed thickness of the device wafer 23 is formed at the intersection.

When the non-through hole 17 is formed, a horizontal movement mechanism is used to move the first chuck in a spiral shape at 1 mm/sec. For example, the focal point of the laser beam L 1 of the first _one, intersecting the central portion of the week from outside the intersecting portion, to be moved in a spiral shape.

After the non-through holes 17 are formed at all the intersections, the wafer unit is transferred from the first laser processing device to the water-soluble resin coating and cleaning device. However, when the resin tape is not attached to the wafer 11, a Bernoulli-type transport pad is used to transport the wafer 11 to the water-soluble resin coating and cleaning device. Then, while the back surface 11b side of the wafer 11 is sucked and held by the cleaning disk, the cleaning disk is rotated, for example, at 2000 rpm.

Next, the cleaning nozzle is positioned on the surface 11a side of the wafer 11 being rotated. By operating the drive source, the cleaning nozzle is reciprocated in an arc on the surface 11a of the wafer 11, and the cleaning liquid is sprayed from the cleaning nozzle. Thus, the water-soluble resin is removed from the surface 11a side along with the dust generated by the ablation.

Fig. 2(B) is an overall view of the surface 11a side of the wafer 11 after the hole forming step (S10), and Fig. 2(C) is a partial enlarged view of the surface 11a side of the wafer 11 after the hole forming step (S10) . In FIG. 2(B) and FIG. 2(C), the non-through hole 17 formed at the intersection of the planned dividing line 13 is shown as a black circle.

After the hole forming step (S10), when an ultraviolet-curable adhesive layer is used on the resin tape attached to the back surface 11b side, the adhesive layer is irradiated with ultraviolet rays on the back surface 11b side. As a result, the adhesive force is reduced, and the resin tape can be easily peeled from the back surface 11b side.

Next, a protective tape (protective member) 19 formed of resin with a diameter larger than that of the wafer 11 is attached to the surface 11a of the wafer 11. The protective tape 19 has, for example, a laminated structure of a substrate layer and an adhesive layer (paste layer), and the adhesive layer is attached to the surface 11a side.

The base layer is formed of, for example, polyolefin (PO). A part or the whole of one surface of the substrate layer is formed on the adhesive layer. The adhesive layer is made of, for example, ultraviolet-curable resin, which is formed of rubber, acrylic, silicone, etc.

However, the protective tape 19 is not limited to the laminated structure of the base material layer and the adhesive layer. For example, the protective tape 19 may have only a substrate layer. At this time, on the surface 11a side of the wafer 11, the protective tape 19 is attached to the wafer 11 via the substrate layer by heat pressing.

After the protective tape 19 is attached to the surface 11a side, the protective tape 19 and the wafer 11 are made to have approximately the same diameter, and the protective tape 19 is cut into a circular shape. Thereby, the surface 11a side is covered with the protective tape 19 (surface protection step (S20)). After that, the resin tape attached to the side of the back surface 11b is removed from the wafer 11.

After the surface protection step (S20), a region with low strength (ie, a modified layer) is formed inside the wafer 11 along the planned dividing line 13 (internal processing step (ie, a modified layer forming step) ( S30)). Fig. 3(A) is a diagram showing the internal processing step (S30).

In order to form the modified layer 21 in the internal processing step (S30), for example, the second laser processing device is used. The second laser processing apparatus is provided with a second chuck (not shown) that sucks and holds the back surface 11b side of the wafer 11.

The second chuck is a porous plate (not shown) having a disc shape, for example. The lower side of the porous plate is connected to a suction source (not shown) such as an ejector through a flow path (not shown) formed inside the second chuck. When the suction source is operated, negative pressure is generated on the upper surface (holding surface) of the porous plate.

Below the second chuck, there is a horizontal moving mechanism (not shown). The horizontal movement mechanism moves the second chuck along the processing conveying direction (X-axis direction) and the classifying conveying direction (Y-axis direction). In addition, under the horizontal movement mechanism, a rotation drive source (not shown) for spinning the second chuck around a specific rotation axis is provided.

Above the second chuck, a second laser beam irradiation unit 12 is provided. The second laser beam irradiation unit 12 has a second laser oscillator (not shown) that generates a pulsed laser beam.

The second laser oscillator includes, for example, a laser medium such as _{Nd:YVO 4 suitable for laser oscillation.} In the second laser oscillator, a second condenser (not shown) is connected through a specific optical system.

The second concentrator condenses the laser beam emitted from the second laser oscillator to a specific position. The second laser beam L ₂ irradiated from the second condenser has a wavelength (for example, 1342 nm) that passes through the wafer 11. The second laser beam L ₂ is adjusted so that, for example, the average output is 0.8 W or more and 3.2 W or less, and the repetition frequency is 60 kHz or more and 140 kHz or less.

In the internal processing step (S30), first, the back surface 11 side is exposed, and the surface 11a side of the wafer 11 is held on the holding surface. _{Next, the second laser beam L 2 is} irradiated from the back surface 11b side to the wafer 11.

Then, the condensing point of the second laser beam L ₂ is positioned at one end of the planned dividing line 13 and positioned on the back surface 11b side than the depth B in the interior of the wafer 11, and the horizontal movement mechanism is operated , Move the second chuck in the X-axis direction.

For example, by moving the second chuck in the X-axis direction at a specific processing and conveying speed of 300 mm/sec or more and 1400 mm/sec or less, the condensing point is moved from one end of the planned dividing line 13 to the other end.

Multiphoton absorption is generated near the condensing point, forming a region with a lower intensity (that is, fragile) than the area where the _{second laser beam L 2 is not irradiated. Therefore, along the moving path of the condensing point, a comparative} The area where the strength is low (that is, the modified layer 21).

In this embodiment, by changing the depth position of the condensing point, three modified layers 21 are formed along one planned dividing line 13. However, the number of modified layers 21 formed along one planned dividing line 13 is not limited to three, and may be two or more than four.

After forming three modified layers 21 along a planned dividing line 13, the second laser beam irradiation unit 12 is transported in stages along the Y-axis direction only for a specific length, and the second laser beam L ₂ is irradiated The position is positioned on the other predetermined dividing line 13.

Next, move the condensing point of the second laser beam L ₂ along the other planned dividing line 13 to form three different changes in the inner depth of the wafer 11 in the same way as the planned dividing line 13质层21。 Quality layer 21. After forming three modified layers 21 inside the wafer 11 along all the planned dividing lines 13 that are slightly parallel to the X-axis direction, the second chuck is rotated by 90°.

Then, similarly, along each planned dividing line 13, move _{the condensing point of the second laser beam L 2} in the X-axis direction, so that three along each planned dividing line 13 are formed inside the wafer 11改质层21。 Improved layer 21. In this way, the modified layer 21 is formed inside the wafer 11 along all the planned dividing lines 13.

Fig. 3(B) is an overall view of the surface 11a side of the wafer 11 after the internal processing step (S30), and Fig. 3(C) is an enlarged part of the surface 11a side of the wafer 11 after the internal processing step (S30) Figure. In FIG. 3(B) and FIG. 3(C), the modified layer 21 is shown with a dotted line.

However, when a single crystal silicon wafer is used as the wafer 11, the wafer 11 has a cleavage property and is cleavage at a specific angle. 4 is a partial cross-sectional side view of the wafer 11 illustrating the cleavage angle of the wafer 11.

Generally, as the surface 11a of the wafer 11, the (100) surface of the silicon wafer is used. Therefore, when the bottom of the non-through hole 17 is parallel to the surface 11a, the surface constituting the bottom of the non-through hole 17 also becomes the (100) plane. In contrast, the cleavage surface of the silicon wafer is, for example, the (111) surface.

In the example shown in FIG. 4, the bottom surface of the non-through hole 17 is a circle with a diameter C, and the plurality of modified layers 21 are formed directly below the center of the bottom surface of the non-through hole 17. The angle θ formed by the (111) plane and the (100) plane of the end 21b on the surface 11a side of the modified layer 21a located on the outermost surface 11a side of the plurality of modified layers 21 is arccos((3) ^-1/2 ) From the table, it is about 54.7 degrees.

The distance D from the end 21b to the bottom surface of the non-through hole 17 is represented by D=(C/2)·tanθ. For example, when the diameter C is 30 μm, the distance D is about 21 μm. (111) Splitting in the plane direction is generated from the end 21b as the starting point. By making the end 21b on the side of the surface 11a at a depth of approximately 21 μm from the bottom surface of the non-through hole 17, a plurality of modified layers 21 can be formed. Prevent the cracks that progress from the end 21b from reaching the surface 11a.

After the internal processing step (S30), the back side 11b side of the wafer 11 is polished (back side polishing step (S40)). Fig. 5(A) is a diagram showing the back side polishing step (S40). In order to grind the back side 11b side, a grinding device is used.

The grinding device is equipped with a third chuck (not shown) that sucks and holds the wafer 11. The third chuck is a porous plate (not shown) having a disk shape, for example.

The lower side of the porous plate is connected to a suction source (not shown) such as an ejector through a flow path (not shown) formed inside the third chuck. When the suction source is operated, negative pressure is generated on the upper surface (holding surface) of the porous plate.

At the lower part of the third chuck, a rotary drive source (not shown) such as a motor is connected. In addition, a grinding unit 14 is provided above the third chuck. The grinding unit 14 has a spindle housing (not shown), and an elevating mechanism (not shown) for raising and lowering the grinding unit 14 in the Z-axis direction is connected to the spindle housing.

In the main shaft housing, a part of the main shaft 16 is housed in a rotatable form. One end of the main shaft housing 16 is connected to a motor for driving the main shaft 16. The other end of the main shaft 16 protrudes from the main shaft housing, and a disc-shaped wheel frame 18 is fixed at the other end.

Under the wheel frame 18, a grinding wheel 20 having the same diameter as that of the wheel frame 18 is installed. The grinding wheel 20 has a ring-shaped wheel base 22 formed of a metal material such as aluminum or stainless steel.

The wheel base 22 is fixed to the wheel frame 18 via the upper side of the wheel base 22, and the wheel base 22 is installed on the main shaft 16. On the lower side of the wheel base 22, a plurality of grinding stones 24 are provided. A plurality of grinding stones 24 are arranged in the circumferential direction of the lower surface of the wheel base 22, and are arranged in a ring shape with a gap between the adjacent grinding stones 24.

Each grinding stone 24 is formed by mixing, for example, a bonding material of metal, ceramic, resin, etc., with abrasive grains such as diamond cBN (cubic boron nitride). However, there is no restriction on the bonding material or the abrasive grains, and it can be appropriately selected corresponding to the shape of the abrasive grindstone 24.

On the lower surface side of the wheel base 22 and on the inner peripheral side of the plurality of grinding stones 24, plural openings (not shown) for supplying grinding water such as pure water to the grinding stones 24 are formed. However, instead of providing an opening for polishing water supply on the lower surface side of the wheel base 22, a polishing water supply nozzle (not shown) may be installed above the third chuck.

In the back side polishing step (S40), first, the surface 11a of the wafer 11 is sucked and held on the holding surface of the third chuck by the protective tape 19. Then, the third chuck is rotated in a specific direction at 10 rpm, and the grinding wheel 20 is rotated at 3000 rpm, and the grinding wheel 20 is transported to the processing worker at a specific speed (for example, 0.6 μm/s) by a lifting mechanism. .

As a result, the grinding stone 24 is pressed on the back surface 11b side of the wafer 11 until the back surface 11b side of the wafer 11 reaches a specific finished thickness, and the back surface 11b side is polished. However, at the time of grinding, for example, the grinding water is supplied to the grinding stone 24 at a specific flow rate of 3.0 L/min or more and 7.0 L/min or less.

When stress is applied to the wafer 11 during polishing, the modified layer 21 is used as the starting point for division, and cracks (not shown) progress to the surface 11a and the back surface 11b. After the cracks reach the front surface 11a and the back surface 11b of the wafer 11, the wafer 11 is divided into a plurality of device chips 23 (refer to FIG. 6).

Fig. 5(B) is an overall view of the surface 11a side of the wafer 11 after the back side grinding step (S40), and Fig. 5(C) is the part on the surface 11a side of the wafer 11 after the back side grinding step (S40) Zoom in. FIG. 6 is a perspective view of the device chip 23. The device chip 23 is attached to the four corners, and a recess corresponding to a part of the side wall of the non-through hole 17 is formed.

In the first embodiment, in the hole forming step (S10), the non-through hole 17 having a depth B that is deeper than the depth A corresponding to the greater thickness is formed at the intersection, and therefore the back side polishing step (S40) The corners of the device chips 23 can be prevented from rubbing against each other.

Therefore, the occurrence of defects in the corners of the device chip 23 can be prevented. In addition, it is possible to prevent defects generated at the corners of the device chip 23 and advance to the field of forming the device 15 (functional element). As a result, for example, compared to when the non-through hole 17 is not formed in the wafer 11, the flexural strength of the device chip 23 can be increased.

As described above, in the hole forming step (S10) of the present embodiment, the first laser beam irradiation unit 10 is used to form the non-through hole 17 through laser ablation. In contrast, in the etching process using expensive photomasks, etc., a photomask is required corresponding to the types of patterns formed on the wafer 11. Therefore, in this embodiment, compared with the etching process, there is an advantage that the design of the position and shape of the non-through hole 17 can be changed flexibly.

Furthermore, in the present embodiment, the non-through hole 17 is formed, for example, compared with the through hole formation, there is an advantage that the time required for the hole forming step (S10) can be shortened. Next, a second embodiment in which through holes are formed will be described.

In the hole forming step (S10) of the second embodiment, instead of the non-through hole 17, a through hole penetrating from the front surface 11a to the back surface 11b of the wafer 11 is formed. The relevant part is different from the first embodiment. The other parts are the same as in the first embodiment.

Fig. 8 is a diagram relating to the hole forming step (S10) of the second embodiment. However, FIG. 8 shows a resin tape 27 that will be attached to the surface 11a side and constitute a wafer unit.

In the hole forming step (S10) related to the second embodiment, first, the water-soluble resin is spin-coated on the entire surface 11a side. Next, the first laser beam irradiation unit 10 is used to irradiate the first laser beam L ₁ to the intersection on the surface 11a side, and a through hole 25 is formed at the intersection.

When the through hole 25 is formed, the first chuck is moved in a spiral shape by a horizontal movement mechanism. At this time, for example, when the first chuck is moved at a processing conveying speed that is slower than the processing conveying speed of the first embodiment, the through hole 25 can be formed in the wafer 11. However, with the conveying speed of the machining of the first embodiment becomes the same premise, the average output of the laser beam L can of a first embodiment of _a first aspect is relatively high.

After the through holes 25 are formed at all the intersections, the wafer unit is transported to a water-soluble resin coating and cleaning device to clean the wafer 11. In this way, the wafer 11 in which the through hole 25 is formed is formed at each intersection.

Next, the third embodiment will be described. Fig. 9 is a flowchart related to the manufacturing method of the third embodiment. In the third embodiment, after the surface protection step (S20) and the internal processing step (S30), the hole forming step (S35) is performed.

More specifically, after the internal processing step (S30), a round resin tape (not shown) larger than the diameter of the wafer 11 is attached to the back side 11b side, and attached to the outer periphery of the resin tape Ring frame. Then, in the surface protection step (S20), the protective tape 19 attached to the surface 11a side is peeled off (back surface protection step (S33)).

After the back surface protection step (S33), the hole forming step (S35) is performed in the same manner as the hole forming step (S10) of the first embodiment. As a result, non-through holes 17 are formed at each intersection of the planned dividing line 13.

Then, after the hole forming step (S35), the surface 11a side is covered with a protective tape 19, and the resin tape attached to the back surface 11b side is peeled off (additional surface protection step (S37)).

After the additional surface protection step (S37), similar to the first embodiment, the back side polishing step (S40) is performed to polish the wafer 11 to the finished thickness. In the third embodiment, the back side polishing step (S40) is also used to prevent the corners of the device wafer 23 from rubbing against each other, and the occurrence of defects in the corners of the device wafer 23 can be prevented.

Next, the fourth embodiment will be described. In the fourth embodiment, in the hole forming step (S35) of the third embodiment, as in the second embodiment, the non-through holes 17 are not formed but the through holes 25 are formed. The relevant part is different from the third embodiment. The other parts are the same as in the third embodiment.

In the fourth embodiment, the back side polishing step (S40) is also used to prevent the corners of the device wafer 23 from rubbing against each other, and the occurrence of defects in the corners of the device wafer 23 can be prevented. In addition, the structure, method, etc. of the above-mentioned embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

11: Wafer 11a: Surface 11b: Backside 13: Planned dividing line 15: Device 17: Non-through hole 19: Protective tape (protection member) 21, 21a: Modified layer 21b: End 23: Device wafer 25: Through hole 27: Resin tape 10: The first laser beam irradiation unit 12: The second laser beam irradiation unit 14: Grinding unit 16: Spindle 18: Wheel frame 20: Grinding wheel 22: Wheel base 24: Grinding stone A : Depth B: Depth C: Diameter D: Distance L ₁ : The first laser beam L ₂ : The second laser beam

[Figure 1] Oblique view of the wafer. [Fig. 2] Fig. 2(A) is a diagram showing the hole forming step, Fig. 2(B) is an overall view of the surface side of the wafer after the hole forming step, and Fig. 2(C) is the wafer after the hole forming step An enlarged view of part of the surface side. [Figure 3] Figure 3(A) is a diagram showing the internal processing steps, Figure 3(B) is an overall view of the surface side of the wafer after the internal processing steps, and Figure 3(C) is the wafer after the internal processing steps An enlarged view of part of the surface side. [Figure 4] A partial cross-sectional side view of a wafer illustrating the split angle of the wafer. [Fig. 5] Fig. 5(A) is a diagram showing the back side grinding step, Fig. 5(B) is an overall view of the surface side of the wafer after the back side grinding step, and Fig. 5(C) is after the back side grinding step An enlarged view of the surface side of the wafer. [Figure 6] An oblique view of the device chip. [Fig. 7] A flow chart of the manufacturing method of plural device chips. [Fig. 8] A diagram related to the hole forming step of the second embodiment. [Fig. 9] A flowchart related to the manufacturing method of the third embodiment.

10: The first laser beam irradiation unit

11: Wafer

11a: surface

11b: back

13: Divide the planned line

15: device

17: Non-through hole

A: depth

B: depth

L ₁ : The first laser beam

Claims (3)

A method of manufacturing plural device wafers, forming a device to be processed in plural areas divided by plural predetermined dividing lines set in a grid pattern on the surface side, and dividing into each device wafer along the respective predetermined dividing lines , The method of manufacturing plural device chips from the workpiece, which is characterized by The first laser beam having the wavelength absorbed in the workpiece is irradiated from the outside of the workpiece to the surface side, and holes deeper than the depth equivalent to the finished thickness of each device chip are formed in the plurality of holes The step of forming the hole at the intersection where the planned dividing line intersects, And a surface protection step in which the surface side of the workpiece is covered with a protective member, And positioning the focal point of the second laser beam with the wavelength that passes through the workpiece in a state where the depth of the finished thickness is located inside the workpiece on the back side of the workpiece, The second laser beam is irradiated from the back side along each predetermined dividing line, and a region having a lower intensity than the region where the second laser beam is not irradiated is formed in the internal processing of the workpiece step, Before the workpiece becomes the finished thickness, the rear side of the workpiece is polished, and the workpiece is divided into a plurality of device wafers for the rear side polishing step. The method for manufacturing a plurality of device wafers according to claim 1, wherein, in the hole forming step, as the hole, a non-through hole that does not penetrate from the surface to the back surface is formed. The method for manufacturing a plurality of device wafers according to claim 1, wherein, in the hole forming step, as the hole, a through hole that penetrates from the surface to the back surface is formed.

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