JP2004082319A - Grinding method of chip and ring frame fixing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a chip with a desired thickness and without cracks and nicks in a effective way. <P>SOLUTION: A wafer 24 is stuck at the center of a tape 23 that is stuck to occlude an aperture of a ring frame 22 and chips 25 are also stuck around the wafer. The ring frame 22 including the chips 25 is fixed in a chuck table 18 that can rotate by itself. The chuck table 18 is rotated and the wafer 24 and the chips 25 are ground with a rotating grinding wheel 21. The thickness of the chips 25 is controlled indirectly by measuring the thickness of the wafer 24. Chips having no cracks and nicks can be formed by grinding the chips 25 that are fixed firmly and the thickness control of the chips 25 can be made indirectly by measuring the thickness of the wafer 24 in grinding. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a chip grinding method for grinding a chip such as a semiconductor chip to a predetermined thickness.
[0002]
[Prior art]
A semiconductor chip on which an integrated circuit is formed is usually formed by grinding a semiconductor wafer to a predetermined thickness and then dicing.
[0003]
In recent years, in order to reduce the thickness, size, and weight of various devices such as mobile phones and notebook personal computers, semiconductor chips have been required to be formed as extremely thin as 100 μm or less and 50 μm or less. Even for such an extremely thin semiconductor chip, if a method is used in which a semiconductor wafer is formed to a predetermined thickness by grinding and then divided by dicing to obtain individual semiconductor chips, chipping or cracking of the semiconductor chip is likely to occur during dicing. There is a problem.
[0004]
In order to avoid such an adverse effect, a technique has been proposed in which, after being divided into individual semiconductor chips by dicing, the semiconductor chips are ground to form a predetermined thickness (for example, Patent Document 1 and Patent Document 1). 2).
[0005]
[Patent Document 1]
JP-A-6-224299 (page 3, FIG. 1)
[Patent Document 2]
JP-A-2001-351890 (page 5, FIG. 5)
[0006]
[Problems to be solved by the invention]
However, the invention disclosed in Patent Literature 1 does not have means for measuring the thickness, and thus has a problem that the finished thickness of the chip cannot be grasped. In addition, since the chip to be polished is held on the surface of the chuck table in a state of being integrated with the frame via the adhesive tape, as the chip becomes thinner due to polishing, the abrasive grindstone eventually hits the frame. It is impossible to grind the chip thinner than the frame.
[0007]
On the other hand, in the invention disclosed in Patent Document 2, although the above-mentioned adverse effects do not occur, since the ring frame is also ground, it can function as a ring frame that holds a chip after being ground and thinned. This causes inconvenience in later conveyance and the like. In addition, since the ring frame is formed by cutting into a circle, there is a problem that it takes time to manufacture.
[0008]
Therefore, in grinding a semiconductor chip, there is a problem in avoiding the above-mentioned inconvenience and forming a chip having a desired thickness and having no crack or chip by an efficient method.
[0009]
[Means for Solving the Problems]
The present invention as a specific means for solving the above problems is a method of grinding a chip to a predetermined thickness by grinding the surface of the chip, wherein the tape is adhered so as to close the opening of the ring frame. A chip attaching step of attaching a wafer to a central region and attaching a chip around the wafer, a ring frame fixing step of fixing a ring frame integrated with the chip to a rotatable chuck table, and a chuck. A chip grinding process in which a table is rotated and a rotating grinding wheel is brought into contact with a wafer and a chip for grinding, and a chip thickness management process in which the thickness of a chip is indirectly managed by measuring the thickness of the wafer. The present invention provides a method for grinding a chip comprising:
[0010]
In the chip grinding method, in the ring frame fixing step, the ring frame is retracted to a retracted position where the grinding of the wafer and the chip is not hindered, and is fixed to the chuck table. Part is formed, the chuck table is constituted by a suction part having a diameter smaller than the inner diameter of the ring frame, and a locking part for fixing the locked part at a retracted position not in contact with the grinding wheel, and in the ring frame fixing step Is that the wafer and the chip are sucked at the suction portion via the tape, the locked portion is locked and fixed by the locking portion at the retracted position, the chip is a semiconductor chip, and the wafer is the same as the semiconductor chip. It is an additional requirement that it be formed of the above material.
[0011]
According to the chip processing method configured as described above, the divided chips are attached to tape around the wafer and ground together with the ring frame via the tape, and the thickness of the wafer is reduced. By measuring the thickness, the thickness of the chip can be indirectly determined, so that even if the chip becomes thin, cracking or chipping does not occur.
[0012]
In addition, since the grinding is performed with the ring frame positioned at the retracted position, the grinding wheel does not come into contact with the ring frame.
[0013]
Further, the present invention is a ring frame fixing mechanism for fixing a ring frame integrated with the work piece to a chuck table, wherein the work piece is attached to a tape stuck so as to close the opening, A plurality of locked portions are formed on the outer periphery of the frame, and the chuck table has a suction portion having a diameter smaller than the inner diameter of the ring frame, and a locking portion for fixing the locked portion at a retracted position not in contact with the grinding wheel. The workpiece is sucked at the suction portion via the tape, and the locked portion is locked and fixed by the locking portion at the retracted position to provide a ring frame fixing mechanism.
[0014]
According to the ring frame fixing mechanism configured as described above, the locked portion that constitutes the ring frame is fixed at the retracted position that does not contact the grinding wheel, so that it hinders the grinding of the held workpiece. Grinding can be performed smoothly to a desired thickness without any problems.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
As an example of an embodiment of the present invention, a case will be described in which a semiconductor chip is ground to a desired thickness by using a grinding apparatus 10 shown in FIG.
[0016]
In the grinding device 10 shown in FIG. 1, a wall portion 12 is provided upright from an end of a base 11, and a pair of rails 13 is vertically disposed on an inner surface of the wall portion 12. A support plate 14 is slidably engaged with the rail 13.
[0017]
Then, as the support plate 14 is moved up and down along the rail 13 by being driven by the pulse motor 15, the grinding means 16 attached to the support plate 14 is configured to move up and down.
[0018]
A turntable 17 is provided on the base 11 so as to be rotatable, and a chuck table 18 is further provided on the turntable 17 so as to be able to rotate and revolve. Around the turntable 17, a thickness measuring means 17a for measuring the thickness of the object to be ground held on the chuck table 18 is provided. As the thickness measuring means, for example, a stylus type height gauge can be used. The number of chuck tables 18 may be one, or three or more.
[0019]
In the grinding means 16, a grinding wheel 20 is mounted on a mounter 19 a formed at the tip of a spindle 19 having a vertical axis, and a grinding wheel 21 is fixed to the lower surface of the grinding wheel 20. The grinding wheel 21 is configured to rotate with the rotation of the spindle 19.
[0020]
The chuck table 18 is provided with a suction portion 18a for suctioning an object to be ground at a center portion of the upper surface, and a plurality of locking portions 18b projecting outward from the side surface to hold the ring frame. It is desirable that the locking portion 18b be slidable in order to accommodate ring frames of various sizes and to improve operability when fixing the ring frame.
[0021]
The semiconductor chip to be ground is held by the ring frame 22 shown in FIG. The ring frame 22 is a ring-shaped member in which an opening 22a that opens at the center and a locked portion 22b that protrudes outward are formed.
[0022]
As shown in FIG. 3, an adhesive tape 23 is attached to the back side of the ring frame 22 with the adhesive surface facing upward to close the opening 22 a, and no circuit is formed in the central region of the adhesive tape 23. A semiconductor wafer 24 made of a material is attached, and a plurality of semiconductor chips 25 are attached around the semiconductor wafer 24 with the circuit surface facing the adhesive tape 23 and the back surface facing the front (chip attaching step). The semiconductor wafer 24 to be attached here is a relatively small one, for example, about 4 inches.
[0023]
In this chip attaching step, the semiconductor wafer 24 and the plurality of semiconductor chips 25 are actually arranged in the opening 22a of the ring frame 22, and the ring frame 22, the semiconductor wafer 24, and the This is performed by simultaneously attaching the adhesive tape 23 to the chip 25.
[0024]
In this manner, when the locked portion 22b of the ring frame 22 is locked and fixed by the locking portion 18b of the chuck table 18, the semiconductor wafer 24 and the plurality of semiconductor chips 25 are attracted via the adhesive tape 23. The suction is performed at the portion 18a (ring frame fixing step). Here, the suction portion 18a has a smaller diameter than the inner diameter of the ring frame 22, that is, the outer diameter of the opening 22a.
[0025]
FIG. 4 shows a state in which the locked portion 22 b of the ring frame 22 is fixed by the locking portion 18 b of the chuck table 18, and in this state, the ring frame 22 is attached to the suction portion 18 a of the chuck table 18. It is fixed below the surface. That is, in the ring frame fixing step, the ring frame 22 is retracted to a retracted position where the grinding of the semiconductor wafer 24 and the semiconductor chip 25 does not occur.
[0026]
Here, the semiconductor wafer 24 and the semiconductor chip 25 may be different materials, but are desirably the same material. For example, when the semiconductor chip 25 is a silicon chip, it is preferable that the semiconductor wafer 24 is also formed of silicon.
[0027]
Then, while the grinding wheel 21 rotates with the rotation of the spindle 19, the grinding means 16 moves down, the chuck table 18 rotates, and the rotating grinding wheel 21 comes into contact with the semiconductor wafer 24 and the semiconductor chip 25 to reduce the pressing force. By being added, the surfaces of the semiconductor wafer 24 and the semiconductor chip 25 are ground (chip grinding step).
[0028]
Since the semiconductor wafer 24 is held at the center of the suction portion 18a, as shown in FIG. 4, when the grinding wheel 21 is positioned so as to always contact the center of the semiconductor wafer 24, the semiconductor wafer 24 and its surroundings are Of the semiconductor chip 25 is uniformly ground.
[0029]
During the grinding, the thickness of the semiconductor wafer 24 can be constantly measured by the one stylus 17b constituting the thickness measuring means 17a being in contact with the upper surface of the semiconductor wafer 24 (chip thickness management step). . Therefore, the thickness of the semiconductor chip 25 can be accurately managed indirectly by measuring the thickness of the semiconductor wafer 24 even during grinding.
[0030]
Here, it is possible to directly measure the thickness of the semiconductor chip 25. However, the semiconductor chip 25 may be damaged by the stylus and the grinding must be interrupted, resulting in extremely low productivity. However, since the semiconductor wafer 24 and the semiconductor chip 25 are ground at the same time and the thicknesses of the two are equal, the thickness of the semiconductor chip 25 can be indirectly and efficiently obtained from the thickness of the semiconductor wafer 24.
[0031]
Further, the locked portion 22b of the ring frame 22 is fixed at the retracted position, which is a position lower than the suction portion 18a of the chuck table 18, and the grinding wheel 21 does not contact the ring frame 22. Can be performed smoothly, and grinding can be performed until the semiconductor wafer 24 and the semiconductor chip 25 become extremely thin.
[0032]
Furthermore, since it is not necessary to divide the semiconductor chip by dicing after grinding, the semiconductor chip does not crack or chip. Therefore, the quality of the semiconductor chip can be improved.
[0033]
In the present embodiment, the case of grinding a semiconductor chip has been described as an example, but the object of grinding is not limited to this, and other small pieces (chips) may be used.
[0034]
Next, the ring frame fixing mechanism 26 that can be suitably used for carrying out the grinding method according to the present invention will be described with reference to FIG.
[0035]
The ring frame 22 exactly the same as the ring frame 22 shown in FIG. 2 includes an opening 22a and four arrow-shaped locked portions 22b protruding from the outer periphery. A workpiece is accommodated in 22a via an adhesive tape 23.
[0036]
The chuck table 18 which is exactly the same as the chuck table 18 shown in FIG. 3 engages with the suction portion 18a, the main body portion 18f supporting the suction portion 18a, and the locked portion 22b of the ring frame 22 to fix the ring frame 22. And four locking portions 18b whose upper surface is retracted to a retracted position not in contact with the grinding wheel.
[0037]
The locking portion 18b includes a channel portion 18c that abuts on the upper surface of the locked portion 22b and pushes down the ring frame 22, and a fixing portion 18d that fixes the channel portion 18c to the outer periphery of the main body 18f.
[0038]
The upper surface of the channel portion 18c constituting the locking portion 18b is positioned at the same height as or slightly lower than the upper surface of the suction portion 18a. It is formed to be larger than the circumferential width of the locked portion 22b that constitutes it.
[0039]
The ring frame 22 and the chuck table 18 thus formed constitute a ring frame fixing mechanism 26 according to the present invention.
[0040]
Next, a procedure for fixing the ring frame 22 accommodating the semiconductor wafer W as the workpiece in the opening 22a via the adhesive tape 23 to the chuck table 18 will be described with reference to FIG.
[0041]
Each of the four locked portions 22b formed on the ring frame 22 is positioned between the adjacent channel portions 18c formed on the chuck table 18, and the semiconductor wafer W is positioned on the suction portion 18a. Then, the ring frame 22 is pressed against the chuck table 18.
[0042]
Each of the four locked portions 22b is positioned at a position where the upper surface of the locked portion 22b of the ring frame 22 is slightly lower than the lower surface of the channel portion 18c formed on the chuck table 18. The ring frame 22 is rotated in the direction of the inclined portion 22c formed on the locked portion 22b, that is, in the direction indicated by the arrow A, until the ring frame 22 is accommodated in the individual channel portions 18c.
[0043]
In this state, when the pressing of the ring frame 22 is released and the suction force is transmitted to the suction portion 18a of the chuck table 18, the semiconductor wafer W is suction-held by the suction portion 18a via the adhesive tape 23, and the ring frame 22 is engaged. Locked to the stop 18b.
[0044]
When the locked portion 22b of the ring frame 22 is accommodated in the channel portion 18c, the locked portion 22b gradually widens from the inclined portion 22c in the radial direction so that the rotation of the ring frame 22 is restricted. It is preferable that the channel portion 18c is formed corresponding to the shape of the locked portion 22b. Further, the number of the locked portion 22b and the channel portion 18c is not limited to four, but may be any number as long as it is three or more.
[0045]
The object to be ground using the ring frame fixing mechanism 26 according to the present invention is not limited to a small piece, and may be a workpiece such as a semiconductor wafer before being divided. In particular, for a semiconductor wafer that is ground extremely thinly, for example, 100 μm or less, handling after grinding becomes difficult. Therefore, the semiconductor wafer W is held by, for example, the ring frame 22 shown in FIG.
[0046]
As shown in FIG. 5, in the ring frame fixing mechanism 26, the semiconductor wafer W is attached to the tape 23 attached so as to cover the opening 22a of the ring frame 22, and the semiconductor wafer is subjected to the same procedure as described above. The ring frame 22 integrated with W is fixed to the chuck table 18 and retracted to a position where the ring frame 22 does not contact the grinding wheel.
[0047]
In this state, as shown in FIG. 6, the semiconductor wafer W, which is an example of the workpiece, is sucked at the suction portion 18 a via the tape 23, and the locked portion 22 b of the ring frame 22 is attached to the grinding wheel 21. At the evacuation position where it does not contact, it is locked and fixed by the locking portion 18b of the chuck table 18.
[0048]
When the locked portion 22b is fixed at the retracted position in this manner, the ring frame 22 is fixed below the surface of the suction portion 18a of the chuck table 18, so that during the grinding of the semiconductor wafer W, Grinding can be performed without the grinding wheel 21 contacting the ring frame 22. Therefore, the semiconductor wafer W can be smoothly ground to a desired thickness.
[0049]
It is to be noted that the holding is not limited to the semiconductor wafer, and if this ring frame fixing mechanism 26 is used, all the plate-like objects can be held at the time of grinding.
[0050]
【The invention's effect】
As described above, according to the chip processing method of the present invention, the wafer is not ground and then divided, but after the division, the chip is attached to a tape around the wafer and the ring frame is formed via the tape. Grinding in an integrated state and measuring the thickness of the wafer being ground can indirectly determine and manage the chip thickness, so cracks and chips may occur even when the chips become thinner It is possible to obtain a desired thickness without any problem and to improve the quality of the chip.
[0051]
In addition, since the grinding is performed with the ring frame positioned at the retracted position, the grinding wheel does not come into contact with the ring frame, so that the grinding can be smoothly performed, and the grinding is performed until the chip becomes extremely thin. Can be.
[0052]
Furthermore, according to the ring frame fixing mechanism according to the present invention, the locked portion constituting the ring frame is fixed at the retracted position not in contact with the grinding wheel, which hinders the grinding of the held workpiece. Grinding can be performed smoothly to a desired thickness without any problems.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a grinding device used for carrying out the present invention.
FIG. 2 is a perspective view showing an example of a ring frame used for carrying out the present invention.
FIG. 3 is a perspective view showing a wafer and a chip held on the ring frame via a tape, and a chuck table holding the ring frame, the wafer and the chip.
FIG. 4 is an explanatory view showing a state of grinding the wafer and the chip.
FIG. 5 is a perspective view showing a semiconductor wafer held on a ring frame via a tape, and a chuck table holding the ring frame and the semiconductor wafer.
FIG. 6 is an explanatory view showing a state in which a semiconductor wafer is held and ground by a ring frame fixing mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Grinding apparatus 11 ... Base 12 ... Wall part 13 ... Rail 14 ... Support plate 15 ... Pulse motor 16 ... Grinding means 17 ... Turntable 17a ... Thickness measuring means 17b, 17c ... Stylus 18 ... Chuck table 18a ... Suction Part 18b ... Locking part 18c ... Channel part 18d ... Fixing part 18f ... Main body part 19 ... Spindle 19a ... Mounter 20 ... Grinding wheel 21 ... Grinding wheel 22 ... Ring frame 22a ... Opening 22b ... Locked part 22c ... Inclination 23 adhesive tape 24 semiconductor wafer 25 semiconductor chip 26 ring frame fixing mechanism W semiconductor wafer

Claims (5)

A chip grinding method for grinding a surface of a chip to a predetermined thickness,
Attaching the wafer to the center region of the tape attached so as to cover the opening of the ring frame, and a chip attaching step of attaching chips around the wafer,
A ring frame fixing step of fixing a ring frame integrated with the chip to a rotatable chuck table;
A chip grinding step of rotating the chuck table and rotating the grinding wheel in contact with the wafer and the chip to perform grinding.
A chip thickness management step of indirectly managing the thickness of the chip by measuring the thickness of the wafer. 2. The chip grinding method according to claim 1, wherein, in the ring frame fixing step, the ring frame is retracted to a retracted position where the grinding of the wafer and the chip does not hinder and fixed to the chuck table. A plurality of locked parts are formed on the outer periphery of the ring frame,
The chuck table includes a suction portion having a diameter smaller than the inner diameter of the ring frame, and a locking portion that fixes the locked portion at a retracted position that does not contact the grinding wheel,
3. The ring frame fixing step according to claim 2, wherein the wafer and the chip are sucked at the suction portion via a tape, and the locked portion is locked and fixed by the locking portion at the retracted position. Chip grinding method. 4. The chip grinding method according to claim 1, wherein the chip is a semiconductor chip, and the wafer is formed of the same material as the semiconductor chip. A ring frame fixing mechanism for fixing a ring frame integrated with the work piece to a chuck table, the work piece being stuck to a tape stuck to close the opening,
A plurality of locked portions are formed on the outer periphery of the ring frame,
The chuck table includes a suction part having a diameter smaller than the inner diameter of the ring frame, and a locking part that fixes the locked part at a retracted position that does not come into contact with the grinding wheel, and the workpiece includes the tape. A ring frame fixing mechanism that is sucked by the suction portion through the suction portion, and the locked portion is locked and fixed by the locking portion at the retracted position.

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