JP2012124300A - Wafer breaking method and wafer breaking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely break a wafer in a short time without interfering with a mount frame.SOLUTION: A breaking device comprises a surface protection film adhesion part (200) for attaching a surface protection film (3) onto a surface of a wafer; a laser processing part (150) for forming a belt-like reformation area (86) inside the wafer by radiating a laser, with a light condensing point being positioned in the inside of the wafer ; a grinding part (350) for grinding a rear surface of the wafer until it reaches the reformation area; a dicing film adhesion part (400) for attaching a dicing film (33) onto the rear surface of the wafer and coupling the wafer with the mount frame; a gripping member (13) for gripping the mount frame so that the surface of the wafer is directed upward; and a pressing member (17) for pressing the rear surface of the wafer via the dicing film. The pressing member is moved on the rear surface of the wafer at least in one direction, so as to break the wafer along the reformation area.

Description

  The present invention relates to a wafer breaking method for breaking a wafer and a wafer breaking apparatus for carrying out such a method.

  In the semiconductor manufacturing field, wafers tend to increase in size year by year, and wafers are becoming thinner to increase mounting density. In order to thin the wafer, back grinding (back surface grinding) is performed to grind the back surface of the wafer. Prior to back grinding, a surface protective film is applied to the surface of the wafer in order to protect the circuit pattern formed on the surface of the wafer.

  By the way, in recent years, laser dicing has been performed in which a band-shaped modified region is formed inside a wafer by matching the focal point of a pulsed laser beam having a wavelength transmissive to the wafer with the thickness of the wafer. (See Patent Document 1). Since the modified region is formed near the surface of the wafer, the wafer naturally cracks in the thickness direction from the modified region toward the surface. Therefore, if a modified region corresponding to the circuit pattern is formed in advance by laser dicing, the wafer is naturally divided into a plurality of chips by back grinding.

  By the way, an error of several micrometer unit occurs in the dimension of the modified region formed in the laser dicing. For this reason, even when the wafer is ground to the modified region, as shown in FIG. 8, a situation may occur in which the modified region is not partially exposed on the back surface of the wafer. In places where the modified region is not exposed, adjacent chips are not separated from each other. For this reason, if the expanding process is performed in a state where there are unseparated chips, such a chip is subjected to a great deal of stress, which causes damage to the semiconductor element.

  In order to cope with such a problem, in Patent Document 2, from the back side of the wafer, the ridge line of the external force applying member having a triangular cross section is positioned and pressed along the modified region, and the wafer is removed from the modified region. It breaks properly. Then, the wafer is reliably separated into a plurality of chips by performing such a breaking process for all the modified regions.

JP 2008-6492 A JP 2010-0451117 A

  However, as in Patent Document 2, if the breaking process using the external force applying member is performed on all the modified regions, the time required for the entire breaking process becomes enormous. Furthermore, it is difficult to accurately position the external force application member in the reformed region, and positioning the external force application member at an incorrect location may cause a great deal of damage to the chip.

  Furthermore, after the wafer is integrated with the mount frame by the dicing film, the length of the external force applying member is limited to the dimension of the mount frame. That is, when the external force applying member is long, the external force applying member partially interferes with the mount frame, and therefore it is difficult to appropriately apply the external force to the wafer. In particular, when an external force is applied along the modified region located near the edge of the wafer, it is impossible to apply the external force because both ends of the external force applying member interfere with the mount frame.

  The present invention has been made in view of such circumstances, and even for a wafer integrated with a mount frame, the wafer can be accurately broken in a short time without interfering with the mount frame. It is an object of the present invention to provide a wafer breaking method that can be performed and a wafer breaking device that performs such a method.

  In order to achieve the above-described object, according to the first invention, in a breaking method for breaking a wafer, a surface protection film is attached to the surface of the wafer, and a laser beam is irradiated with a focusing point inside the wafer. By forming a band-shaped modified region inside the wafer, grinding the back surface of the wafer until reaching the modified region or the vicinity of the modified region, pasting a dicing film on the back surface of the wafer A wafer is coupled to the mount frame, the mount frame is held by a holding member so that the front surface of the wafer faces upward, and the back surface of the wafer held by the holding member is pressed by the pressing member through the dicing film. Moving the pressing member in at least one direction on the back surface of the wafer, thereby Breaking the wafer along the modified region, breaking method is provided.

  According to the second invention, in the first invention, the pressing member is moved in two directions perpendicular to each other on the back surface of the wafer.

  According to a third aspect, in the first or second aspect, the method further includes peeling the surface protection film from the front surface of the wafer before pressing the back surface of the wafer by the pressing member.

  According to a fourth invention, in any one of the first to third inventions, the pressing member includes a spherical surface, or the pressing member is a cylindrical member having a length shorter than the radius of the wafer. Part.

  According to the fifth aspect, in the breaking device for breaking the wafer, the surface protective film sticking portion for sticking the surface protective film to the surface of the wafer, and the laser beam is irradiated with the focusing point inside the wafer. A laser processing unit for forming a band-shaped modified region inside the wafer, a grinding unit for grinding the back surface of the wafer until reaching the modified region or the vicinity of the modified region, and a back surface of the wafer. A dicing film affixing unit for affixing a dicing film to bond the wafer to the mount frame, a gripping member for gripping the mount frame so that the surface of the wafer faces upward, and the wafer gripped by the gripping member A pressing member that presses the back surface through the dicing film, and the pressing member is The back surface of the wafer is moved in at least one direction, thereby breaking along the wafer to the modified region, breaking apparatus is provided.

  According to a sixth aspect, in the fifth aspect, the pressing member is moved in two directions perpendicular to each other on the back surface of the wafer.

  According to a seventh aspect, in the fifth or sixth aspect, the surface protective film peeling means for peeling the surface protective film from the front surface of the wafer before pressing the back surface of the wafer by the pressing member. It has.

  According to an eighth invention, in any one of the fifth to seventh inventions, the pressing member includes a spherical surface, or the pressing member is a cylindrical member having a length shorter than the radius of the wafer. Part.

  In the first and fifth aspects, the pressing member can be moved without interfering with the mounting frame by making the pressing member sufficiently smaller than the mounting frame. Therefore, even if the wafer is integrated with the mount frame, the wafer can be accurately broken. In addition, the portion where the modified region is not exposed on the back surface of the wafer after grinding has a generally similar tendency determined according to the laser processing unit and / or the grinding unit. For this reason, the wafer can be broken in a short time by pressing only the portion where the modified region is not exposed.

  In the second and sixth inventions, the wafer can be reliably separated into a plurality of chips.

  In the third and seventh inventions, the wafer can be broken even when the surface protective film is peeled off. In addition, when a surface protection film exists, since the force from a pressing member cannot transmit directly to a wafer, it is preferable that a surface protection film does not exist at the time of the press by a pressing member.

  In the fourth and eighth inventions, since the pressing member is sufficiently smaller than the mount frame, the wafer can be broken by moving the pressing member without interfering with the mount frame.

1 is a schematic diagram showing a wafer processing apparatus including a breaking apparatus according to the present invention. It is a figure which shows a wafer. It is a sectional side view for demonstrating a laser dicing. (A) It is a schematic side view which shows the 1st state of the back surface grinding in a back surface grinding unit. (B) It is a schematic side view which shows the 2nd state of the back surface grinding in a back surface grinding unit. It is a side view of the breaking device based on this invention. FIG. 6 is a bottom view of the breaking device shown in FIG. 5. (A) It is a figure which shows operation | movement of the press member of a fracture | rupture apparatus. (B) It is another figure which shows operation | movement of the press member of a fracture | rupture apparatus. It is a top view of the wafer after back surface grinding.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
FIG. 1 is a schematic diagram showing a wafer processing apparatus including a breaking apparatus according to the present invention. Further, FIG. 2 is a view showing a wafer. As shown in FIG. 2, a plurality of circuit patterns C are formed in a lattice pattern on the surface 21 of the wafer 20 in the previous step. Such a circuit pattern C is not formed on the back surface 22 of the wafer 20. It is assumed that such a wafer 20 is supplied to the wafer processing apparatus 100 shown in FIG.

  As shown in FIG. 1, the wafer processing apparatus 100 includes a laser processing unit 150 that forms a modified region 86 in a thickness portion of the wafer 20 by laser dicing, and a surface protection film 3 attached to the surface 21 of the wafer 20. A surface protection film attaching unit 200 for reversing the wafer 20, a reverse unit 300 for turning the wafer 20 upside down, a back grinding unit 350 for grinding the back surface 22 of the wafer 20, and a dicing film 33 on the back surface 22 of the wafer 20. A dicing film affixing unit 400 for bonding the wafer 20 to the mount frame 15, a surface protection film peeling unit 450 for peeling the surface protection film 3 from the surface 21 of the wafer 20, and pressing the wafer 20 with a roller so Breaking unit that breaks along And (500) are in mainly include. Between each unit of the wafer processing apparatus 100, a moving device such as a robot arm is used to move the wafer 20. However, these are general devices, and illustration and description thereof are omitted.

  The wafer 20 is first supplied to the laser processing unit 150 of the wafer processing apparatus 100. FIG. 3 is a sectional side view for explaining laser dicing performed in the laser processing unit 150. In FIG. 3, the laser V is irradiated from the laser source (not shown) to the surface 21 side of the wafer 20 through the condenser lens 85 under the condition that multiphoton absorption occurs. At this time, the condensing point 84 is adjusted to a side somewhat closer to the surface 21 inside the wafer 20. Thereby, a modified region 86 is formed around the condensing point 84. Next, when the laser V and the condenser lens 85 are moved along the arrow X <b> 3, a band-shaped modified region 86 is formed inside the wafer 20.

  In laser dicing, the modified region 86 is formed by transmitting the laser V through the wafer 20 and generating multiphoton absorption inside the wafer 20. Therefore, the laser V is hardly absorbed by the wafer 20 on the surface 21 of the wafer 20, and as a result, the surface 21 of the wafer 20 is not melted, and cracks or the like deviated from the planned cutting line are formed on the surface of the wafer. It does not occur.

  Since the modified region 86 is formed on a side somewhat closer to the surface 21, if the modified region 86 is naturally cracked in the thickness direction toward the surface 21, a groove corresponding to the width of the laser V is formed. become. Such modified regions 86 are formed in a lattice shape along the circuit pattern C.

  Next, the wafer 20 is transferred from the laser processing unit 150 to the surface protective film attaching unit 200. The surface protective film 3 serves to protect the circuit pattern C formed on the surface 21 of the wafer 20 in a back grinding process as a post process. Note that the processing by the laser processing unit 150 may be performed by supplying the wafer 20 to which the surface protective film 3 has been attached in advance to the wafer processing apparatus 100.

  After the surface protective film 3 is attached, the wafer 20 is transferred from the attaching unit 200 to the reversing unit 300. The inversion unit 300 serves to invert the wafer 20. The wafer 20 having the surface protection film 3 attached to the surface 21 in the attaching unit 200 has the surface 21 facing upward. Therefore, in the reversing unit 300, such a wafer 20 is turned upside down, and the surface 21 of the wafer 20 to which the surface protective film 3 is attached faces downward.

  The wafer 20 reversed in the reversing unit 300 is supplied to the back surface grinding unit 350 shown in FIG. The wafer 20 is supplied to the back surface grinding unit 350 with the back surface 22 facing upward. Fig.4 (a) is a schematic side view which shows the state of the back surface grinding in a back surface grinding unit. As shown in FIG. 4A, in the back surface grinding unit 350, the front surface 21 of the wafer 20 is sucked by a suction portion (not shown). As described above, since the surface protection film 3 is adhered to the surface 21 of the wafer 20 in the affixing unit 200, even if the surface 21 of the wafer 20 is adsorbed, a circuit formed on the surface 21 Pattern C is not damaged.

  Next, a grinding part 81 is arranged on the back surface 22 of the wafer 20, and the grinding part 81 reciprocates on the back surface 22 of the wafer 20 in the direction of the arrow as shown in FIG. Then, the back surface 22 of the wafer 20 is ground until reaching the modified region 86 or beyond the modified region 86 (see FIG. 4B). Thereby, the wafer 20 is divided into a plurality of chips while being held by the surface protective film 3.

  However, the place where the modified region 86 is formed may vary in the thickness direction of the wafer 20. In such a case, even if grinding is performed beyond the modified region 86, a certain chip remains connected to another adjacent chip or the outer peripheral portion of the wafer 20. Such a problem is solved in the breaking unit 500 described later.

  Next, the wafer 20 is supplied to the dicing film attaching unit 400. In the dicing film attaching unit 400, the dicing film 33 is attached to the wafer 20 by a known method. As a result, the wafer 20 is integrated with the mount frame 15, and therefore, the back-ground ground wafer 20 can be easily handled.

  Next, the wafer 20 is supplied to the surface protective film peeling unit 450. In the surface protective film peeling unit 450, first, the peeling tape 4 is attached to the surface protective film 110 of the wafer 20, and then the peeling tape 4 is wound up. Since the adhesive force between the peeling tape 4 and the surface protective film 110 is higher than the adhesive force between the surface protective film 110 and the wafer 20, the surface protective film 110 is peeled from the wafer 20 when the peeling tape 4 is wound. As a result, the surface 21 of the wafer 20 is exposed.

  Thereafter, the wafer 20 is supplied to the breaking unit 500. FIG. 5 is a side view of the breaking device arranged in the breaking unit 500, and FIG. 6 is a bottom view of the breaking device shown in FIG. As shown in these drawings, the breaking device has a gripping member 13 that grips both ends of an annular mount frame 15. Further, the gripping device includes an X direction rail 11 extending in the X direction and a Y direction rail 12 perpendicular to the X direction rail 11.

  As shown in FIG. 5, a concave groove 11 a extending in the longitudinal direction is formed on the upper surface of the X-direction rail 11. In addition, a convex portion 12a that engages with the concave groove 11a is provided at the center of the lower surface of the Y-direction rail 12. Accordingly, the Y-direction rail 12 can slide on the X-direction rail 11.

  Furthermore, as shown in FIG. 5, the breaking device includes a slider 16 that slides on the Y-direction rail 12. The slider 16 incorporates a spring-biased pressing member 17. The pressing member 17 has a curved surface that makes point contact with the wafer 20 and protrudes upward from the top surface of the slider 16. Or you may make it raise / lower the press member 17 in the slider 16 using the drive part which is not shown in figure.

  In the embodiment shown in FIGS. 5 and 6, the pressing member 17 includes a part of a spherical surface. However, in an embodiment not shown, the pressing member 17 may include a part of the peripheral surface of the cylindrical member. Further, it is preferable that the pressing member 17 is sufficiently small with respect to the wafer 20, so that the slider 16 having the pressing member 17 can be moved within the wafer 20 without interfering with the mount frame 15 in the region of the wafer 20. It comes to slide. In a preferred embodiment, the size of the pressing member 17 in the direction parallel to the wafer 20 is smaller than the radius of the wafer 20.

  In the breaking unit 500, the mount frame 15 gripped by the gripping member 13 is fixed at a predetermined position, so that the X-direction rail 11 and the Y-direction rail 12 are positioned on the back surface 22 side of the wafer 20. In such an arrangement, the tip of the pressing member 17 is at a position corresponding to the modified region 86 of the wafer 20. Further, in the height direction, the tip of the pressing member 17 is at a position sufficient to press the wafer 20 through the dicing film 33. As a result, the modified region 86 located at a position corresponding to the pressing member 17 is pressed, and the wafer 20 is cracked upward from the modified region 86 toward the surface 21.

  FIG. 7A and FIG. 7B are views showing the operation of the pressing member of the breaking device. As can be seen from FIGS. 6 and 7A, the slider 16 slides along the Y direction on the Y direction rail 12 while pressing the wafer 20 at a position corresponding to the modified region 86. Thereby, even when a part of the modified region 86 remains on the wafer 20, the force from the slider 16 is applied to the modified region 86 when the slider 16 passes below the modified region 86. . As a result, the wafer 20 is cracked upward from the modified region 86 toward the surface 21.

  When the slider 16 reaches the vicinity of the edge of the wafer 20, the slider 16 stops at that position, and the Y-direction rail 12 itself slides on the X-direction rail 11 in the minus X direction. The moving distance of the Y-direction rail 12 is equal to the distance between adjacent modified regions 86, that is, the dimension of the circuit pattern C. Then, with the Y-direction rail 12 stopped, the slider 16 is slid on the Y-direction rail 12 in the minus Y direction.

  As a result, the wafer 20 is similarly cracked from the modified region 86 adjacent to the modified region 86 described above. When such an operation in the Y direction is repeated over the entire wafer 20 as shown in FIG. 7A, the wafer 20 is similarly broken at positions corresponding to all the modified regions 86 extending in the Y direction. become.

  Thereafter, as can be seen from FIGS. 6 and 7B, the Y-direction rail 12 is moved in the X direction along the X-direction rail 11 while the slider 16 is stopped on the Y-direction rail 12. When the Y direction rail 12 reaches the vicinity of the edge of the wafer 20, the Y direction rail 12 stops at that position, and the slider 16 slides on the Y direction rail 12 in the minus Y direction. As described above, the moving distance of the slider 16 is equal to the distance between the adjacent modified regions 86. Then, with the slider 16 stopped, the Y-direction rail 12 is slid on the X-direction rail 11 in the minus X direction.

  When the operation in the X direction is repeated over the entire wafer 20 as shown in FIG. 7B, the wafer 20 is similarly broken at positions corresponding to all the modified regions 86 extending in the X direction. become.

  Thus, in the present invention, the slider 16 provided with the pressing member 17 is moved in the X direction and the Y direction. It becomes possible to separate.

  After releasing the gripping member 13, the wafer 20 is supplied to the expanding unit 600 shown in FIG. 1 and subjected to a predetermined expanding process. In the present invention, all circuit patterns C are separated into pieces in the breaking unit 500 of the wafer 20. Accordingly, when the wafer 20 is expanded, all the circuit patterns C are separated from each other without applying a lateral stress to the circuit pattern C.

  Note that the surface protection film 3 may be peeled off in the surface protection film peeling unit 450 after the wafer 20 is broken in the breaking unit 500. However, in the state where the surface protection film 3 is present, the force hardly acts on the wafer 20 directly. For this reason, it is preferable to perform the breaking process in the breaking unit 500 after the surface protective film 3 is peeled off, so that the wafer 20 can be appropriately broken.

  Furthermore, in the embodiment shown in FIGS. 7A and 7B, the wafer 20 is pressed in all the modified regions 86, but only the modified region 86 in a part of the wafer 20 is broken. Processing may be performed. The region in the wafer 20 where the modified region 86 is not partially exposed after back grinding depends on the laser processing unit 150 and / or the back grinding unit 350 used (see FIG. 8). Therefore, it is only necessary to grasp in advance a region where the modified region 86 is not partially exposed and operate the slider 16 only for that region to perform the breaking process. In this case, since the movement of the slider 16 is minimal, it will be understood that the wafer 20 can be broken in a shorter time than the prior art.

DESCRIPTION OF SYMBOLS 3 Surface protection film 11 X direction rail 12 Y direction rail 13 Holding member 15 Mount frame 16 Slider 17 Press member 20 Wafer 21 Front surface 22 Back surface 33 Dicing film 86 Modified area | region 100 Wafer processing apparatus 150 Laser processing unit 200 Surface protection film sticking unit 300 Reversing unit 350 Back surface grinding unit 400 Dicing film pasting unit 450 Surface protective film peeling unit 500 Breaking unit

Claims (8)

In the breaking method to break the wafer,
A surface protective film is attached to the surface of the wafer,
By irradiating a laser with a focusing point inside the wafer, a band-shaped modified region is formed inside the wafer,
Grind the backside of the wafer until it reaches the modified region or near the modified region,
Affixing a dicing film on the back surface of the wafer and bonding the wafer to a mount frame,
Grip the mount frame with a gripping member so that the surface of the wafer faces upward,
Press the back surface of the wafer gripped by the gripping member with the pressing member through the dicing film,
A breaking method, wherein the pressing member is moved in at least one direction on the back surface of the wafer, thereby breaking the wafer along the modified region.   The breaking method according to claim 1, wherein the pressing member is moved in two directions perpendicular to each other on the back surface of the wafer.   The breaking method according to claim 1, further comprising peeling the surface protection film from the front surface of the wafer before pressing the back surface of the wafer by the pressing member.   The breaking method according to any one of claims 1 to 3, wherein the pressing member includes a spherical surface, or the pressing member is a part of a cylindrical member having a length shorter than a radius of the wafer. In a breaking device for breaking a wafer,
A surface protection film affixing part for affixing a surface protection film to the surface of the wafer;
A laser processing unit that forms a band-shaped modified region inside the wafer by irradiating a laser with a focusing point inside the wafer, and
A grinding unit for grinding the back surface of the wafer until the modified region or the vicinity of the modified region is reached;
A dicing film sticking portion for attaching a dicing film to the back surface of the wafer and bonding the wafer to a mount frame;
A gripping member for gripping the mount frame so that the surface of the wafer faces upward,
A pressing member that presses the back surface of the wafer gripped by the gripping member through the dicing film,
A breaking device that moves the pressing member in at least one direction on the back surface of the wafer, thereby breaking the wafer along the modified region.   6. The breaking device according to claim 5, wherein the pressing member is moved in two directions perpendicular to each other on the back surface of the wafer.   The breaking device according to claim 5 or 6, further comprising surface protective film peeling means for peeling the surface protective film from the front surface of the wafer before pressing the back surface of the wafer by the pressing member.   The breaking device according to any one of claims 5 to 7, wherein the pressing member includes a spherical surface, or the pressing member is a part of a cylindrical member having a length shorter than a radius of the wafer.

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