JP2004119468A - Wafer-level package dividing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer-level package dividing method wherein a wafer is divided into semiconductor chips without causing cracks therein by using a dicing-before-grinding technique. <P>SOLUTION: In this wafer-level package deviding method, a semiconductor wafer 21, whose top surface is divided along a plurality of streets 22 into a plurality of regions each mounted with a circuit having solder balls 24 attached thereto, is divided into individual semiconductor chip packages. Dividing grooves having a depth equivalent to the thickness of finished semiconductor chips are formed along the streets 22 in the top surface of the semiconductor wafer 21, a resin coating process is then implemented wherein a resin 25 is laid to be thick enough to bury the solder balls 24 on the top surface the semiconductor wafer 21, and finally a dividing process is implemented wherein the rear surface of the semiconductor 21 is ground for the dividing grooves to be exposed in the rear surface of the semiconductor wafer 21. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, a circuit is formed in each of a plurality of areas defined by a plurality of streets on a surface of a semiconductor wafer, and a wafer level package in which solder balls are attached to the surface of each circuit is divided into semiconductor chips for each circuit. The present invention relates to a method for dividing a wafer level package.
[0002]
[Prior art]
In a semiconductor device manufacturing process, circuits such as ICs and LSIs are formed in a large number of regions arranged in a lattice on the surface of a semiconductor wafer having a substantially disk shape, and each region where the circuits are formed is formed into a predetermined street. Individual semiconductor chips are manufactured by dicing along a cutting line called "cutting line". The semiconductor chips thus divided are packaged and widely used for electric devices such as mobile phones and personal computers. In order to improve the heat dissipation of the semiconductor chip, it is desirable to form the semiconductor chip as thin as possible. In addition, in order to enable miniaturization of a mobile phone, a smart card, a personal computer, and the like using a large number of semiconductor elements, it is desirable to form the semiconductor elements as thin as possible.
[0003]
As a technology that can reduce the thickness of a semiconductor chip, a cutting groove having a predetermined depth (a depth corresponding to the finished thickness of a semiconductor chip) is formed in advance from a front surface in a cutting device before grinding the back surface of the semiconductor wafer. A so-called pre-dicing method, in which a back surface of a semiconductor wafer is ground by a grinding device to expose a cut groove to divide the semiconductor wafer into individual semiconductor chips, is widely used. In addition, since the protective tape is stuck on the front surface of the semiconductor wafer whose back surface is ground, the individually divided semiconductor chips do not fall apart and the state of the semiconductor wafer is maintained.
[0004]
On the other hand, electrical devices such as mobile phones and personal computers are required to be lighter and smaller, and a package technology for a semiconductor chip called a chip size package (CSP) has been developed. As one of the CSP technologies, solder balls are attached to bonding pads constituting each semiconductor chip in a state of a semiconductor wafer having a large number of circuits formed on a surface, and are divided along a street and then packaged without packaging. The ultimate CSP technology called a wafer level package configured to be directly incorporated into a motherboard is also in practical use. Therefore, if the wafer level package can be divided into semiconductor chips by the pre-dicing method, the ultimate CSP with a desired thickness can be obtained.
[0005]
[Problems to be solved by the invention]
In the wafer level package, solder balls are mounted on the surface of a semiconductor wafer on which a large number of circuits are formed, and the height of the solder balls is 80 to 200 μm. It will be supported by the ball. As a result, the grinding load acting on the back surface of the semiconductor wafer is received by the solder ball, and there is a problem that the semiconductor wafer is cracked when the back surface of the semiconductor wafer is ground and the thickness thereof is reduced.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a main technical problem thereof is to provide a method of dividing a wafer level package which can be divided without being divided into semiconductor chips by a dicing method.
[0007]
[Means for Solving the Problems]
According to the present invention, there is provided a wafer in which a circuit is formed in each of a plurality of areas defined by a plurality of streets on a surface of a semiconductor wafer, and a solder ball is attached to a surface of each circuit. A method of dividing a wafer level package, which divides a level package into semiconductor chips for each circuit, a resin coating step of coating a resin with a thickness such that the solder balls are embedded on a surface of the semiconductor wafer,
A dividing groove forming step of forming a dividing groove having a depth corresponding to the finished thickness of each semiconductor chip along the street on the surface of the semiconductor wafer;
A protective member attaching step of attaching a protective member to the surface of the semiconductor wafer on which the division grooves are formed,
A grinding step of grinding the back surface of the semiconductor wafer to which the protective member is attached, exposing a dividing groove, and dividing the semiconductor wafer into a plurality of semiconductor chips.
A method for dividing a wafer level package is provided.
[0008]
Further, according to the present invention, a circuit is formed in each of a plurality of areas defined by a plurality of streets on a surface of a semiconductor wafer, and a wafer level package in which solder balls are attached to the surface of each circuit is provided for each circuit. A method of dividing a wafer level package into semiconductor chips,
A dividing groove forming step of forming a dividing groove having a depth corresponding to the finished thickness of each semiconductor chip along the street on the surface of the semiconductor wafer;
A resin coating step of coating the resin with a thickness such that the solder balls are embedded on the surface of the semiconductor wafer;
A protective member attaching step of attaching a protective member to the surface of the resin-coated semiconductor wafer,
A grinding step of grinding the back surface of the semiconductor wafer to which the protective member is attached, exposing a dividing groove, and dividing the semiconductor wafer into a plurality of semiconductor chips.
A method for dividing a wafer level package is provided.
[0009]
Further, according to the present invention, the back surfaces of the plurality of semiconductor chips divided by the dividing step and adhered to the protective member are adhered to the protective sheet attached to the pickup frame, and the protective member is attached to the plurality of protective sheets. A method for dividing a wafer level package is provided, which includes a transfer step of peeling off from a surface of a semiconductor chip and a resin removing step of removing resin coated on surfaces of a plurality of semiconductor chips attached to a protective sheet. .
The resin coated on the surface of the semiconductor wafer in the resin coating step is preferably a water-soluble resin.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method for dividing a wafer level package according to the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 is a perspective view showing a wafer level package processed according to the present invention, and FIG. 2 is a cross-sectional view showing a part of the wafer level package in an enlarged manner. The wafer level package 2 shown in FIGS. 1 and 2 includes a semiconductor wafer 21 formed of silicon or the like, a circuit 23 formed on a surface thereof in a plurality of regions partitioned by a plurality of streets 22, And a plurality of solder balls 24 attached to the bonding pads. In addition, the thickness of the semiconductor wafer 21 is formed to be about 500 μm, and the height of the solder ball 24 is formed to be 80 to 200 μm.
[0012]
A first embodiment in which the above-described wafer level package 2 is divided into individual semiconductor chips will be described with reference to FIGS.
In the first embodiment, first, a resin is coated on the surface of the semiconductor wafer 21 constituting the wafer level package 2 to such a thickness that the solder balls 24 are embedded (resin coating step). Specifically, as shown in FIG. 3, the surface of the semiconductor wafer 21 is coated with a resin by the spin coater 3. That is, the spin coater 3 includes a chuck table 31 provided with a suction holding unit, and a nozzle 32 arranged above the center of the chuck table 31. A semiconductor wafer 21 constituting the wafer level package 2 is placed on a chuck table 31 of the spin coater 3 with its surface facing upward, and while the chuck table 31 is rotating, a liquid resin is applied from a nozzle 32 to the center of the surface of the semiconductor wafer 21. The liquid resin flows to the outer peripheral portion by centrifugal force by dropping on the portion, and coats the surface of the semiconductor wafer 21. Then, by heating the resin coated on the surface of the semiconductor wafer 21 at a predetermined temperature, the resin is hardened and the resin is hardened so as to bury the solder balls 24 on the surface of the semiconductor wafer 21 as shown in FIG. Layer 25 can be formed. The resin for coating the surface of the semiconductor wafer 21 is desirably a water-soluble resist. For example, TPF provided by Tokyo Ohka Kogyo Co., Ltd. is convenient.
[0013]
After the formation of the coating layer 25 on the surface of the semiconductor wafer 21 by the above-described resin coating step, a division groove having a depth corresponding to the finished thickness of each semiconductor chip is formed on the surface of the semiconductor wafer 21 along the street 22. (Division groove forming step). In this division groove forming step, as shown in FIG. 5, a cutting device 4 generally used as a dicing device can be used. That is, the cutting device 4 includes the chuck table 41 having the suction holding unit, and the cutting blade 421 and the cutting unit 42. The semiconductor wafer 21 having the coating layer 25 formed on the chuck table 41 of the cutting device 4 is held with its surface facing upward, and the chuck table 41 is moved in the direction indicated by the arrow X while rotating the cutting blade 421 of the cutting means 42. By cutting and feeding, a dividing groove 26 is formed along the street 22 as shown in FIG. The dividing groove 26 is set to a depth corresponding to the finished thickness of each divided semiconductor chip.
[0014]
When the dividing grooves 26 are formed along the streets 22 on the surface of the semiconductor wafer 21 by the above-described dividing groove forming step, the semiconductor wafer 21 is turned upside down as shown in FIG. As shown in (1), the protective member 5 for grinding is mounted on the front side (the side on which the circuit 23 is formed) (protective member attaching step).
[0015]
Next, as described above, the back surface of the semiconductor wafer 21 having the protective member 5 mounted on the front surface is ground to expose the dividing grooves 26 and divide the semiconductor chips into individual semiconductor chips (dividing step). This division step is performed by a grinding device 6 having a grinding means 62 having a chuck table 61 and a grinding wheel 621 as shown in FIG. That is, the semiconductor wafer 21 is held on the chuck table 61 with the back side up, and for example, while the chuck table 61 is rotating at 300 rpm, the grinding wheel 62 of the grinding means 62 is rotated at 6000 rpm, and Grind by contact. Then, when the semiconductor wafer 21 is ground until the division grooves 26 are exposed as shown in FIG. 9, the semiconductor wafer 21 is divided into individual semiconductor chips 20. Since the solder balls 24 provided on the front surface of the semiconductor wafer 21 are buried by the covering layer 25, the back surface of the semiconductor wafer 21 can be ground without being affected by the solder balls 24. Also, the semiconductor wafer 21 does not crack.
[0016]
When the semiconductor wafer 21 is divided into the individual semiconductor chips 20 by the dividing step described above, the semiconductor wafer 21 is adhered to the protective member 5 and the back surface of each semiconductor chip 20 is adhered to the protective sheet attached to the pickup frame. The protection member 5 is peeled off from the surface of each semiconductor chip 20 (transfer step). That is, as shown in FIG. 10A, the protection member 5 and the semiconductor chip 20 attached to the protection member 5 are turned upside down, and the surface of the semiconductor chip 20 is attached to the protection sheet 71 mounted on the pickup frame 7. To wear. Then, as shown in FIG. 10B, the protection member 5 attached to the back surface of the semiconductor chip 20 is peeled off. As a result, as shown in FIG. 10C, the surface of the semiconductor chip 20 attached to the protection sheet 71 of the pickup frame 7 is on the upper side.
[0017]
Next, the resin (coating layer 25) coated on the surface of the semiconductor chip 20 attached to the protection sheet 71 of the pickup frame 7 is removed (resin removing step). In the illustrated embodiment, since the resin (coating layer 25) coated on the surface of the semiconductor chip 20 is formed of a water-soluble resist, it can be washed away with water without using a solvent. By performing the resin removing step as described above, the semiconductor chip 20 from which the resin (coating layer 25) coated on the surface is removed as shown in FIGS. 11A and 11B is obtained. Can be.
[0018]
Next, a second embodiment in which the above-described wafer level package 2 is divided into individual semiconductor chips will be described with reference to FIG.
In the second embodiment, first, a dividing groove having a depth corresponding to the finished thickness (for example, 50 μm) of each semiconductor chip is formed along the street 22 on the surface of the semiconductor wafer 21 constituting the wafer level package 2. A dividing groove forming step is performed. This dividing step is performed by the cutting device 4 as described above. As a result, as shown in FIG. 12A, a division groove 26 having a depth corresponding to the finished thickness of each semiconductor chip divided from its surface is formed in the semiconductor wafer 21.
[0019]
If the dividing grooves 26 are formed along the streets 22 on the surface of the semiconductor wafer 21 by the above-described dividing groove forming step, the resin coating is performed to coat the resin with a thickness enough to bury the solder balls 24 on the surface of the semiconductor wafer 21. Perform the process. This resin coating step is performed by the spin coater 3 as described above. As a result, as shown in FIG. 12B, a coating layer 25 having a thickness such that the solder balls 24 are embedded in the surface of the semiconductor wafer 21 can be formed. At this time, the resin is also filled in the dividing grooves 26 formed in the dividing groove forming step as shown in FIG.
[0020]
Next, a protective member attaching step of attaching the protective member 5 for grinding to the surface of the semiconductor wafer 21 coated with the resin is performed. This protection member attaching step is performed in the same manner as in the first embodiment described above. As a result, as shown in FIG. 12C, the protective member 5 for grinding is mounted on the surface of the semiconductor wafer 21 on the side where the circuit 23 is formed.
[0021]
When the protection member 5 is attached to the front surface of the semiconductor wafer 21 by the protection member attaching step, a division step of grinding the back surface of the semiconductor wafer 21 to expose the division grooves 26 and dividing the semiconductor wafer 21 into individual semiconductor chips is performed. This dividing step is performed by the grinding device 6 as described above. As a result, the semiconductor wafer 21 is divided into individual semiconductor chips 20 as shown in FIG. In this embodiment, in the state where the dividing step is performed, the surfaces of the individual semiconductor chips 20 are connected by a coating layer 25 made of resin, and the dividing grooves 26 are filled with resin. As described above, since the dividing groove 26 is filled with the resin in the state where the dividing step is performed, even if the grinding wheel 621 reaches the dividing groove 26, there is no step and the corner of the semiconductor chip 20 is damaged. There is no.
[0022]
When the semiconductor wafer 21 is divided into the individual semiconductor chips 20 by the dividing step described above, the semiconductor wafer 21 is adhered to the protective member 5 and the back surface of each semiconductor chip 20 is adhered to the protective sheet attached to the pickup frame. A transfer step of peeling the protection member 5 from the surface of each semiconductor chip 20 is performed. This transfer step is performed in the same manner as the transfer step of the first embodiment described above. As a result, as shown in FIG. 12E, the semiconductor chip 20 whose surface is connected by the resin coating layer 25 is attached to the protection sheet 71 of the pickup frame with the surface facing upward.
[0023]
Next, a resin removing step of removing the resin (coating layer 25) coated on the surface of the semiconductor chip 20 attached to the protection sheet 71 of the pickup frame is performed. In this resin removing step, the resin (coating layer 25) is washed away with water as in the resin removing step of the first embodiment described above. As a result, the semiconductor chip 20 from which the resin (coating layer 25) coated on the surface is removed as shown in FIGS. 11A and 11B is obtained.
[0024]
【The invention's effect】
According to the method for dividing a wafer level package according to the present invention, after forming a dividing groove having a depth corresponding to the finished thickness of each semiconductor chip along the street on the surface of the semiconductor wafer, the back surface of the semiconductor wafer is ground. When the dividing grooves are exposed, since the solder balls provided on the surface of the semiconductor wafer are embedded in the resin, the back surface of the semiconductor wafer can be ground without being affected by the solder balls. However, the semiconductor wafer does not break.
Further, according to the method for dividing a wafer level package according to the present invention, since the dividing grooves are filled with the resin, even if the grinding wheel reaches the dividing grooves in the dividing step, there is no step and the corners of the semiconductor chip are damaged. Never give.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a wafer level package processed according to the present invention.
FIG. 2 is an enlarged sectional view showing a part of the wafer level package shown in FIG. 1;
FIG. 3 is an explanatory view of a resin coating step in the dividing method according to the present invention.
FIG. 4 is an enlarged sectional view showing a part of the wafer level package on which a resin coating step has been performed.
FIG. 5 is an explanatory view of a dividing groove forming step in the dividing method according to the present invention.
FIG. 6 is an enlarged cross-sectional view showing a part of the wafer level package on which the dividing groove forming step has been performed.
FIG. 7 is an explanatory view of a protective member attaching step in the dividing method according to the present invention.
FIG. 8 is an explanatory diagram of a dividing step in the dividing method according to the present invention.
FIG. 9 is an enlarged cross-sectional view showing a part of a semiconductor chip in which a wafer level package is individually divided after a dividing step is performed.
FIG. 10 is an explanatory diagram of a transfer step in the dividing method according to the present invention.
FIG. 11 is an explanatory diagram of a resin removing step in the dividing method according to the present invention.
FIG. 12 is an enlarged sectional view showing a part of a wafer level package on which each processing step is performed in another embodiment of the dividing method according to the present invention.
[Explanation of symbols]
2: Semiconductor wafer 20: Semiconductor chip 21: Semiconductor wafer 22: Street 23: Circuit 24: Solder ball 25: Coating layer 26: Dividing groove 3: Spin coater 31: Spin coater chuck table 32: Spin coater nozzle 4: Cutting Apparatus 41: Chuck table 42 of cutting apparatus: Cutting means 421 of cutting apparatus: Cutting blade 5: Protective member 6: Grinding apparatus 61: Chuck table 62: Grinding means 621: Grinding wheel 7: Pickup frame 71: Protection sheet

Claims (4)

A wafer-level package in which a circuit is formed in each of a plurality of regions defined by a plurality of streets on a surface of a semiconductor wafer, and a wafer-level package having solder balls attached to the surface of each circuit is divided into semiconductor chips for each circuit. Is a division method of
A resin coating step of coating the resin with a thickness such that the solder balls are embedded on the surface of the semiconductor wafer;
A dividing groove forming step of forming a dividing groove having a depth corresponding to the finished thickness of each semiconductor chip along the street on the surface of the semiconductor wafer;
A protective member attaching step of attaching a protective member to the surface of the semiconductor wafer on which the division grooves are formed,
A grinding step of grinding the back surface of the semiconductor wafer to which the protective member is attached, exposing a dividing groove, and dividing the semiconductor wafer into a plurality of semiconductor chips.
A method for dividing a wafer-level package. A wafer-level package in which a circuit is formed in each of a plurality of regions defined by a plurality of streets on a surface of a semiconductor wafer, and a wafer-level package having solder balls attached to the surface of each circuit is divided into semiconductor chips for each circuit. Is a division method of
A dividing groove forming step of forming a dividing groove having a depth corresponding to the finished thickness of each semiconductor chip along the street on the surface of the semiconductor wafer;
A resin coating step of coating the resin with a thickness such that the solder balls are embedded on the surface of the semiconductor wafer;
A protective member attaching step of attaching a protective member to the surface of the resin-coated semiconductor wafer,
A grinding step of grinding the back surface of the semiconductor wafer to which the protective member is attached, exposing a dividing groove, and dividing the semiconductor wafer into a plurality of semiconductor chips.
A method for dividing a wafer-level package. The back surfaces of the plurality of semiconductor chips divided by the dividing step and attached to the protective member are attached to a protective sheet attached to a pickup frame, and the protective member is attached to the front surface of the plurality of semiconductor chips. 3. The wafer level package according to claim 1, further comprising: a transfer step of removing the resin from the substrate; and a resin removing step of removing a resin coated on a surface of the plurality of semiconductor chips attached to the protective sheet. 4. Method. 3. The method for dividing a wafer level package according to claim 1, wherein the resin coated on the surface of the semiconductor wafer in the resin coating step is a water-soluble resin.

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