JP4589201B2 - Substrate cutting equipment - Google Patents

Description

The present invention relates to an apparatus for cutting an additional portion of a substrate such as a semiconductor wafer in which an additional portion made of a material such as metal or resin is formed on the surface, and particularly relates to an improvement in cutting scrap processing technology .

  A semiconductor chip having an electronic circuit such as an IC or LSI formed on its surface has a rectangular rectangular area defined by a cut line called street on the surface of a disk-shaped semiconductor wafer, and the electronic circuit is formed in these rectangular areas. Thereafter, the semiconductor wafer is manufactured through a process of dividing the semiconductor wafer along the street and dicing it.

  Some semiconductor wafers have a plurality of metal protrusions formed on the surface or a resin film formed as an insulating means, and some semiconductor wafers have both the metal and the resin film on the surface. For example, there is one in which protruding electrodes called bumps are formed on electrode terminals on a device forming surface of a semiconductor wafer, which are directly bonded to electrodes formed on a mounting substrate. Since this bump is formed on the surface of the device by a method such as plating, the variation in the growth rate due to the plating becomes the variation in the bump height as it is. If the bump height varies, when the bump surface is pressed against the mounting substrate for mounting, partial electrode terminal bonding failure occurs, reducing the product yield of the semiconductor chip. Therefore, in order to avoid such a situation, as disclosed in Patent Documents 1 and 2, for example, a technique has been proposed in which the upper end portions of the bumps are cut before dicing so as to align the heights.

  When manufacturing a semiconductor chip having such a bump, first, the height of the bump is aligned as described above, and then the back side (the side without the bump) of the semiconductor wafer is ground to a predetermined thickness. Later, it was cut along the street to get individual devices. The reason for aligning the bump height first is to hold the semiconductor wafer with the bump side surface aligned with the processing reference surface such as a chuck table, and to grind the exposed back surface to a predetermined thickness. If the thickness is not uniform, the semiconductor wafer cannot be ground to a uniform thickness, and stress may be concentrated on a part of the semiconductor wafer during the grinding.

Japanese Patent Application Laid-Open No. 2000-173954 JP 2004-319697 A

  By the way, when the upper end portion of the bump is cut with the back surface of the semiconductor wafer being sucked by the suction surface of the suction table, the cutting waste generated by the cutting is scattered and attached around the suction table. In addition, when the semiconductor wafer is smaller than the suction table, it is inevitable that cutting chips adhere to the exposed surface of the suction table. In particular, the suction table is equipped with a suction port for vacuum suction and a sword-shaped pin chuck that supports the semiconductor wafer, so that cutting waste is sucked into the suction port by vacuum suction or around the tip of the pin chuck. It is easy to adhere. Furthermore, after the surface of the semiconductor wafer is coated with a resin, the gap between the mounting substrate and the semiconductor chip connected by the bump is filled with the resin by performing a cutting process to align the bump height. ing. If such resin cutting debris adheres to the pin chuck, etc., it cannot be easily removed by washing, and if the next semiconductor wafer is adsorbed in that state, the thickness of the cutting debris becomes a processing error, which increases processing accuracy. Serious effect.

Therefore, an object of the present invention is to provide a substrate cutting apparatus that can eliminate the harmful effects caused by cutting scraps when cutting additional portions such as bumps and maintain the original cutting accuracy. Yes.

The present invention adsorbs and holds a substrate provided with an additional portion made of a metal or resin formed on the surface so as to protrude from the surface, with the suction surface of the suction table aligned with the back surface side of the substrate. A pin cutting device is disposed on the suction surface, and the periphery of the suction surface is a tapered surface that slopes downward toward the outer peripheral side, and on the back surface of the substrate, A holding member that is made of a material having flexibility and protrudes radially outward from the entire circumference of the substrate and protrudes radially outward from the entire circumference of the suction surface of the suction table is adhered to the holding member. the outer peripheral portion of the surface of, in a state of being the adhesive a frame made of rigid material, the retaining member is adsorbed and held on the attracting surface, the retaining member along the tapered surface disposed by weight of the flexibility and the frame , Substrate transport, adsorption It is characterized in that performed by adsorbing the frame by stage.

  According to the present invention, since the holding member protrudes radially outward from the entire circumference of the substrate, the scattered cutting waste of the additional portion is received by the protruding portion of the holding member. Therefore, since the substrate is transferred from the suction table together with the holding member after the cutting process, the cutting waste is not left on the suction table. Therefore, it is possible to eliminate the adverse effects caused by the cutting waste when the additional portion such as the bump is cut, and to maintain the original cutting accuracy. In addition, since the substrate is adhered to a larger holding member, even a small or irregularly shaped substrate can be accommodated and transported to the cassette via the holding member, and adsorbed to another processing stage. And can be held and processed, and the series of steps can be performed smoothly.

  By the way, substrates such as semiconductor wafers tend to become thinner year by year due to demands for miniaturization of semiconductor chips. For this reason, after the bumps are cut, the back surface of the substrate is ground to reduce the thickness. By adopting such a processing order, it is possible to prevent cracks and breakage due to handling of the substrate during the cutting of the bumps.

  However, when the back surface of the substrate is ground after the bumps are cut, the end surfaces of the already cut bumps are fixed to the suction table and processed, so that the end surfaces are likely to be scratched or soiled. In order to prevent such inconvenience, it is conceivable to perform back surface grinding by attaching a protective tape or the like to the bump side surface. However, in such a case, if the protective tape is peeled after the backside grinding, the adhesive of the protective tape may adhere to the resin part covering the tip of the bumps that has been cut and the periphery thereof, and there is a concern that reliability during mounting may be reduced. is there. In order to solve these problems, it has become necessary to handle the thinned substrate and perform bump cutting after grinding the back surface of the semiconductor wafer. For this reason, there is a concern about breakage of the substrate during handling.

  In this respect, in the present invention, since the substrate can be handled via the holding member, even a thinned substrate can be handled without being damaged. Furthermore, in the present invention, since it is not necessary to handle the end face of the cut bump with a contact-type transport pad or the like, there is an advantage that the end face of the bump can be transported and stored in the cassette without being stained or damaged. is there. In addition, the board | substrate of this invention is not limited to a semiconductor wafer, For example, the electronic substrate which provided the wiring, the electronic component, and the semiconductor chip on the surface of the base material made from ceramics is also contained.

In the present invention, since the holding member protrudes radially outwardly from the entire circumference of the suction surface of the suction table, or attached to the pin chuck or the like or cutting debris is sucked into the suction port by the vacuum suction of the suction table Can be surely prevented.

As the holding member, a dicing tape having an adhesive layer on the surface of the substrate can be used. Dicing tapes are known in which a pressure-sensitive adhesive layer is formed on the surface of a base material made of, for example, vinyl chloride or polyolefin having a thickness of 70 to 200 μm. Moreover, a metal plate such as a stainless steel plate is suitable as the rigid material. In the present invention , the periphery of the suction surface of the suction table is a tapered surface that is inclined downward toward the outer peripheral side , and the holding member is disposed along the tapered surface due to its flexibility and the weight of the frame. the thickness of the frame is the height from the rear surface of the substrate to the upper end surface of the bump even when thicker than (after cutting), it is possible to edge of the cutting tool to prevent the interference with the frame.

  According to the present invention, the scattered cutting waste of the additional portion is received by the protruding portion of the holding member, and is transferred from the suction table together with the holding member after cutting, so that the cutting when the additional portion such as a bump is cut The harmful effects caused by scraps can be eliminated, and the original cutting accuracy can be maintained. In addition, since the substrate is adhered to a larger holding member, even a small or irregularly shaped substrate can be accommodated and transported to the cassette via the holding member, and adsorbed to another processing stage. And can be held and processed, and the series of steps can be performed smoothly. Furthermore, the effect that the destruction at the time of handling of the thinned substrate can be prevented is obtained.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Semiconductor Wafer Reference numeral 1 in FIG. 1 represents a disk-shaped semiconductor wafer (substrate, hereinafter abbreviated as a wafer) on which cutting is performed in one embodiment. As shown in the figure, a plurality of semiconductor chips 2 are formed in a lattice pattern on the surface of the wafer 1. On the surface of each semiconductor chip 2, as shown in the enlarged portion of FIG. 1 and FIG. 2, a plurality of bumps 3 having a fine pin shape are formed protrudingly. These bumps 3 are bonded to electrodes of an electronic circuit formed on the semiconductor chip 2 and are made of a metal having excellent conductivity such as gold, nickel, copper, or solder. Further, as shown in FIG. 2, a resin film 4 covering the bumps 3 is formed on the surface of the wafer 1. The resin film 4 is formed leaving a slight outer peripheral portion of the surface of the wafer 1. The resin film is made of a resin such as polyimide, acrylic, or epoxy. In the following description, both the bump 3 and the resin film 4 may be collectively referred to as an additional portion 5.

  The wafer 1 as described above is affixed to the center of the surface of a dicing tape (holding member) 6, and is sucked and held together with the dicing tape 6 during storage, conveyance, and processing. The dicing tape 6 is obtained by providing a pressure-sensitive adhesive layer on the surface of a disk-shaped resin film. A ring-shaped metal frame 7 is attached to the outer periphery of the surface of the dicing tape 6. In the figure, reference numeral 7a denotes an orientation notch.

[2] Configuration of Cutting Device The bumps 3 formed on the surface of the wafer 1 are scraped off together with the resin film 4 to make the height uniform, and the resin film 4 is processed flat accordingly. FIG. 3 shows a cutting device 10 according to an embodiment of the present invention suitable for the machining. Reference numeral 11 in FIG. 3 is a base mainly composed of a rectangular parallelepiped portion having a horizontal upper surface. The base 11 has a wall portion 12 standing perpendicular to the upper surface at one end portion in the longitudinal direction. In FIG. 3, the longitudinal direction, the width direction, and the vertical direction of the base 11 are indicated by arrows Y, X, and Z, respectively.

The upper surface of the base 11 has a processing area 11A from the substantially central portion in the longitudinal direction to the wall 12 side, and the opposite side supplies the unprocessed wafer 1 to the processing area 11A and collects the processed wafer 1. Supply / recovery area 11B.
Hereinafter, the various mechanisms provided in the cutting apparatus 10 will be described mainly by referring to FIG. 3 and divided into those provided in the processing area 11A and those provided in the supply / recovery area 11B.

(A) Mechanism of processing area A rectangular recess 13 is formed in the processing area 11A, and a disk-shaped chuck table (suction table) 15 is placed in the recess 13 via a moving table 14. It is provided so as to be movable in the Y direction. Further, the moving table 14 is slidably attached to the chuck table 15 on a guide rail extending in the Y direction disposed in the base 11 and reciprocates in the same direction by an appropriate drive mechanism (not shown). Be moved.

  One end of bellows-like covers 16 and 17 is attached to both ends of the moving table 14 in the moving direction, and the other ends of the covers 16 and 17 are opposed to the inner surface of the wall portion 12 and the wall portion 12. It is attached to the inner wall surface of the recess 13 to be respectively. These covers 16 and 17 cover the moving path of the moving table 14 and prevent cutting chips and the like from falling on the moving path, and expand and contract as the moving table 14 moves.

  The chuck table 15 is fixed on the moving table 14 so that the upper surface, which is the suction surface of the wafer 1 (dicing tape 6), is horizontal. The wafer 1 is attracted and held on the chuck table 15 by a vacuum chuck method with the surface on which the additional portion 5 is formed facing upward. A plurality of pin chucks 15a are arranged on the chuck table 15 as shown in FIG. 4, and the dicing tape 6 is supported by the sharp tip of the pin chuck 15a. Further, the periphery of the chuck table 15 is a tapered surface that is inclined downward toward the outer peripheral side, and the dicing tape 6 is disposed along the tapered surface due to its flexibility and the weight of the frame 7.

  The chuck table 15 moves to the wall 12 side and is positioned at a predetermined processing position. A cutting unit (cutting means) 20 is disposed above the processing position. The cutting unit 20 is attached to the wall portion 12 via a moving plate 32 and a guide rail 31 so as to be movable up and down, and is moved up and down by a feed mechanism 30.

  The cutting unit 20 includes a cylindrical housing 22 whose axial direction extends in the Z direction, a rotary shaft 23 that is coaxially and rotatably supported by the housing 22, and a servo motor 24 that rotationally drives the rotary shaft 23. A disc-shaped wheel mount 25 coaxially fixed to the lower end of the rotary shaft 23, and the housing 22 is fixed to the moving plate 32 via a block 34. The wheel mount 25 is rotated by the servo motor 24 in the direction of the arrow in FIG. 3 (described on the upper surface of the wheel mount 25). As shown in FIG. 4, a cutting tool 26 having a blade portion made of diamond or the like is detachably attached to the lower surface of the wheel mount 25, and the workpiece is cut by the cutting tool 26. The bite is made of a hard material such as diamond, cemented carbide or CBN.

  The chuck table 15 is reciprocated between a processing position immediately below the cutting unit 20 and a wafer attaching / detaching position that is a predetermined distance away from the wall 12. At the wafer attaching / detaching position, the wafer 1 to be cut is placed on the chuck table 15, and the wafer 1 after the cutting is removed from the chuck table 15.

(B) Mechanism of Supply / Recovery Area As shown in FIG. 3, a rectangular recess 18 is formed in the supply / recovery area 11 </ b> B. A transfer mechanism 60 in which a fork (suction means) 60b is mounted is installed at the tip of a node link type horizontal turning arm 60a.

  A supply arm 63 having a suction plate 63b attached to the front end of the cassette 61, the alignment table 62, and the horizontal turning arm 63a of the first node is disposed around the recess 18 counterclockwise as viewed from above. The recovery arm 64 having the same structure as the supply arm 63, the horizontal turning arm 64a and the suction plate 64b, the spinner type cleaning device 65, and the cassette 66 are arranged.

  The cassette 61, the alignment table 62 and the supply arm 63 are means for supplying the wafer 1 to the chuck table 15, and the recovery arm 64, the cleaning device 65 and the cassette 66 recover the processed wafer 1 from the chuck table 15. Means. Although the two cassettes 61 and 66 have the same structure, they will be referred to as a supply cassette 61 and a recovery cassette 66 depending on the application. These cassettes 61 and 66 are for accommodating and carrying a plurality of wafers 1, and are set at predetermined positions on the base 11.

  A plurality of unprocessed wafers 1 are accommodated in the supply cassette 61 in a stacked state. The transfer mechanism 60 takes out one wafer 1 from the supply cassette 61 by raising / lowering and turning the arm 60a and gripping the fork 60b, and further raises the wafer 1 on the surface on which the additional portion 5 is formed. And has a function of being placed on the alignment table 62 in a state of being directed to.

  On the alignment table 62, the wafer 1 is placed in a fixed state. The supply arm 63 sucks the wafer 1 on the alignment table 62 to the suction plate (suction means) 63b, swings the arm 63a, places the wafer 1 on the chuck table 15, and lowers the horizontal swing arm 63a. After that, the wafer 1 is placed on the chuck table 15 by stopping the suction operation.

  The recovery arm 64 has a function of sucking the processed wafer 1 from the chuck table 15 onto the suction plate (suction means) 64b and turning the arm 64a to transfer the wafer 1 into the cleaning device 65. The cleaning device 65 has a function of rotating the wafer 1 and shaking off the water after the wafer 1 is washed with water. The wafer 1 cleaned by the cleaning device 65 is transferred and accommodated in the collection cassette 66 by the transfer mechanism 60.

  When the wafer 1 is attached to or detached from the chuck table 15 by the supply arm 63 and the recovery arm 64, the movable table 14 is stopped at the wafer attachment / detachment position. In addition, a nozzle 67 that cleans the chuck table 15 by spraying high-pressure air onto the chuck table 15 is disposed between the supply arm 63 and the recovery arm 64. Cleaning of the chuck table 15 by the nozzle 67 is performed on the chuck table 15 at the wafer attachment / detachment position.

[3] Cutting of wafer by cutting device Next, a method of using the cutting device 10 having the above configuration and the operation thereof will be described below.
First, the back surface of the wafer 1 is ground and thinned to a thickness of about 200 μm, and is attached to a dicing tape 6 to have the form shown in FIG. One wafer 1 is taken out by a transfer mechanism 60 from the inside of a supply cassette 61 in which a plurality of dicing tapes 6 with wafer 1 shown in FIG. 1 (hereinafter sometimes collectively referred to as “wafer 1”) are accommodated. The wafer 1 is moved and positioned by the transfer mechanism 60 with the surface facing up to the alignment table 62.

  Next, the wafer 1 is moved from the alignment table 62 by the supply arm 63 to the upper surface of the chuck table 15 that has been previously stopped at the attaching / detaching position, with the surface facing upward. Then, the air suction operation of the chuck table 15 is started, and the wafer 1 is sucked and held on the chuck table 15. In this state, since the dicing tape 6 has a larger diameter than the chuck table 15, the outer peripheral portion of the chuck table 15 is covered and concealed by the dicing tape 6, as shown in FIG.

  Next, while moving the chuck table 15 to the processing position and lowering the cutting unit 20 on which the wheel mount 25 rotates, the surface of the wafer 1, that is, the surface of the bump 3 and the resin film 4 constituting the additional portion 5 by the cutting tool 26. To cut. Then, the cutting chips 8 of the bumps 3 and the resin film 4 are scattered to the outside of the wafer 1, but the scattered cutting chips 8 fall on the dicing tape 6. Further, since the pressure-sensitive adhesive layer is present on the surface of the dicing tape 6, the falling cutting waste adheres to the dicing tape 6.

When the cutting process is completed, the suction operation of the chuck table 15 is stopped, and the holding state of the wafer 1 on the chuck table 15 is released. The wafer 1 released from being held by the chuck table 15 is moved from the attachment / detachment position to the cleaning device 65 by the recovery arm 64. At that time, since the cutting waste 8 is also conveyed while adhering to the dicing tape 6, the cutting waste 8 does not remain on the chuck table 15. The wafer 1 is washed with water by the cleaning device 65 to remove the cutting waste 8 adhering to the surface thereof, and then the moisture is removed. Then, the wafer 1 is moved into the collection cassette 66 by the transfer mechanism 60 and stored. The
The wafer 1 is then conveyed to a cutting device, separated into pieces (dicing) while being attached to the dicing tape 6, and then subjected to a series of processes for manufacturing semiconductor chips such as bonding.

[4] Effect According to the present embodiment, the scattered cutting waste 8 of the additional portion 5 is received by the dicing tape 6 and transferred from the chuck table 15 together with the dicing tape 6 after the cutting process. This can be eliminated, and the original cutting accuracy can be maintained. In particular, in the above embodiment, since the pressure-sensitive adhesive layer is provided on the surface of the dicing tape 6, the fallen cutting waste 8 can be adhered, and the cutting waste 8 bounces off and drops during transportation. Can be prevented.

[5] Modified Example In the above embodiment, the wafer 1 after cutting is adsorbed to the suction plate 64a of the recovery arm 64 and conveyed to the cleaning device 65. As shown in FIG. 7, the frame of the dicing tape 6 is used. It is preferable that the recovery arm 64 is configured to adsorb 7. In the example shown in FIG. 7, a pipe 64c having a cross shape, for example, in plan view, is connected to the tip of the arm 64a, and a suction pad 64d is attached to the lower surface of the end of the pipe 64c. In such a configuration, since the frame 4 is sucked and transported by the four suction pads 64d, the bumps 3 can be prevented from being contaminated or damaged.

In the present invention, the following modifications can be made to the above embodiment.
The present invention can also be applied to a semiconductor wafer in which an adhesive film (DAF: die attach film) is bonded to the back surface. In this case, the adhesive film is adhered to the dicing tape.

1 is a plan view of a semiconductor wafer whose surface is cut by a cutting device according to an embodiment of the present invention. It is an expanded sectional view of the semiconductor wafer shown in FIG. It is a perspective view of the cutting device concerning one embodiment. It is a sectional side view which shows the detail of the chuck table which the cutting device shown in FIG. 3 comprises. It is a top view which shows the detail of the chuck table with which the cutting apparatus shown in FIG. 3 comprises. (A) is a perspective view which shows the wafer affixed on the dicing tape, (B) is a side view which shows the state by which it was adsorbed by the chuck table. It is a partially broken side view which shows the modification of a collection | recovery arm.

Explanation of symbols

1 ... Semiconductor wafer (substrate)
5 ... Additional part 6 ... Dicing tape (holding member)
7 ... Frame 8 ... Cutting waste 15 ... Chuck table (Suction table)
64d ... Adsorption pad (adsorption means)

Claims (2)

A substrate having an additional portion made of a metal or resin formed on the surface so as to protrude from the surface is sucked and held with the suction surface of the suction table aligned with the back surface of the substrate, and the additional portion is cut. A substrate cutting device,
A pin chuck is disposed on the suction surface, and the periphery of the suction surface is a tapered surface that has a downward slope toward the outer peripheral side,
The back surface of the substrate is made of a flexible material and protrudes radially outward from the entire circumference of the substrate and has a size that protrudes radially outward from the entire periphery of the suction surface of the suction table. The member is adhered, and the holding member is adsorbed and held on the adsorption surface in a state in which a frame made of a rigid material is adhered to the outer peripheral portion of the surface of the holding member, and the holding member is attached to the flexibility and the frame. weight by disposed along said tapered surface of,
The substrate cutting apparatus , wherein the substrate is conveyed by adsorbing the frame by an adsorption unit.   The substrate cutting apparatus according to claim 1, wherein the holding member is a dicing tape that holds the substrate when the substrate is cut into individual pieces.

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