JPH10242083A - Dicing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To slightly lower the adhesion of a dicing tape to prevent fine breaks around grooves of a tape and wafer during adhering. SOLUTION: After carrying a frame 12 out of a cassette 21, it is positioned on an ultraviolet irradiator 31 during carrying to a chuck table 26, and slightly irradiated with ultraviolet rays to slightly lower the adhesion of an ultraviolet setting type dicing tape 11 to about 1200g/25mm measured according to JIS Z0237, as well as to lower the flexibility, thus stabilizing the hold condition of a semiconductor wafer 10. The frame 12 holding the semiconductor wafer after the ultraviolet irradiation is carried to and vacuum-held with the table 26 by the revolution of a first conveyer 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dicing a semiconductor wafer, and more particularly, to an ultraviolet-curable dicing tape used as a tape for holding a semiconductor wafer. On the other hand, the present invention relates to a dicing method in which the quality of a chip formed by dicing is improved by slightly irradiating ultraviolet rays before dicing.

[0002]

2. Description of the Related Art In a dicing apparatus 20 shown in FIG. 5 for dicing a semiconductor wafer W, a frame 1 holding a semiconductor wafer 10 via an adhesive tape 11 is used.
2 are stored in the cassette mounting area 22 while about 25 sheets are accommodated in the cassette 21. Then, the frame 12 stored in the cassette 21 is carried out to the frame area 24 by the wafer carrying-in / out means 23, and thereafter, is carried to the chuck table 26 by the turning movement of the first carrying means 25, and is suction-held.

When the semiconductor wafer 10 sucked and held by the chuck table 26 is positioned immediately below the alignment means 27 by the movement of the chuck table 26,
Image processing such as pattern matching for aligning a cutting line called a street for dividing a semiconductor chip such as an IC formed on the surface of the semiconductor wafer 10 with a blade 28 for cutting the street is performed by the alignment means 27. The alignment is performed.

When the alignment is performed, the chuck table 26 moves to a cutting area where the blade 28 is inserted, and in the cutting area, the semiconductor wafer 1 held by the frame 12 held by the chuck table 26 is moved.
The 0 street is cut by the blade 28 to perform dicing.

When the dicing is completed, the chuck table 26 returns to the position where the semiconductor wafer 10 was transferred by the first transfer means 25 before dicing. Then, the suction force of the chuck table 26 is released, and the frame 12 holding the semiconductor wafer 10 is sucked by the second transfer means 29 and transferred to the cleaning / spin drying area 30, where cleaning and spin drying are performed. .

After the semiconductor wafer 10 has been washed and spin-dried in the washing / spin-drying area 30, the semiconductor wafer 10 is transferred to the frame area 24 by the turning movement of the first transfer means 25, and the wafer loading / unloading means is provided. 2
By 3, it is carried into a predetermined place in the cassette 21, and a series of dicing operations is completed.

When dicing is performed in this manner, the semiconductor wafer 10 is divided into individual chips. Since each chip is still held on the frame 12 via the adhesive tape 11, the adhesive strength of the adhesive tape 11 Accordingly, the shape before dicing is maintained as a whole of the semiconductor wafer 10. Therefore, after dicing, a step of picking up individual chips from the adhesive tape 11 is required.

As one method for facilitating the separation of the individual chips from the adhesive tape 11, a method using an ultraviolet-curable dicing tape as the adhesive tape is well known. According to this method, the adhesive force can be sufficiently reduced by sufficiently irradiating the ultraviolet-curable dicing tape with ultraviolet rays (UV) after dicing, and the adhesive is reduced in the next step due to the reduced adhesive force. The chip picking operation can be performed smoothly.

When the irradiation of the ultraviolet rays is performed continuously in a series of dicing steps, the productivity can be improved by providing an ultraviolet irradiation unit 31a or 31b in the dicing apparatus 20.

When the ultraviolet irradiation unit 31a is provided, the diced semiconductor wafer 10 which has been washed and spin-dried in the washing and spin-drying area 30 is used.
To the chuck table 26 using the first transfer means 25.
In the process of turning to the frame region 24 from above, the semiconductor wafer 10 can be positioned just above the ultraviolet irradiation unit 31a and the ultraviolet irradiation can be performed.

On the other hand, when the ultraviolet irradiation unit 31b is provided, means for transferring the diced semiconductor wafer 10 to an upper portion of the ultraviolet irradiation unit 31b;
For example, it is necessary to provide an ultraviolet irradiation transfer means 40 as shown in FIG.

The ultraviolet transport means 40 includes a base 4 provided from the vicinity of the opening of the cassette 21 mounted on the cassette mounting area 22 to the vicinity of the ultraviolet irradiation unit 31b.
2, a transport unit 43 that slides on the base 42 in the PQ direction, a vertical moving unit 44 that moves up and down in the vertical direction, and a suction unit 45 provided at the tip of the vertical moving unit 44.

[0013] The frame area 24 is conveyed from the washing and spin-drying area 30 by the turning movement of the first conveying means 25.
The frame 12 placed on the frame 12 is sucked by the suction unit 45 when the vertically moving unit 44 descends. And
While maintaining the suction state, the vertically moving section 44 is slightly raised, and the transport section 43 is moved in the P direction to be positioned immediately above the ultraviolet irradiation unit 31b.
By slightly lowering the adhesive, the ultraviolet curing type dicing tape 11 is sufficiently irradiated with ultraviolet rays, and the adhesive strength is weakened.

After the irradiation of the ultraviolet rays, the transport section 43 is slid in the Q direction, and the vertically moving section 44 is lowered, so that the suction section 4 is moved.
5 and the frame 12 is placed on the frame area 24 again. Then, the frame 12 holding the diced semiconductor wafer 10 by the ultraviolet-curing dicing tape 11 having weakened adhesive force is accommodated in the cassette 21 by the carrying-in / out means 23.

[0015]

Even when an ultraviolet-curable dicing tape is used as the adhesive tape as in the above-mentioned conventional example, the semiconductor wafer is exposed to the ultraviolet light because dicing has not yet been performed. It is held by the strong adhesive force of the curable dicing tape.

The UV-curable dicing tape also has the property that the flexibility decreases with the decrease in the adhesive strength, and that the tape is cured. Is also higher. Therefore, there is a problem that the holding state of the semiconductor wafer during dicing becomes unstable due to this flexibility.

This unstable holding state causes a small chipping (chipping) 51 as shown in FIG. 7 when cutting the street, and this chipping 51 is caused by the chip 50 having an IC package. This may cause cracking when packaged, or cause cracks due to intermittent ON / OFF of current after packaging.

Therefore, the conventional dicing has a problem to be solved in that chipping is reduced by stably holding the semiconductor wafer and chip quality is improved.

[0019]

As means for solving the above problems, the present invention provides at least a step of arranging a semiconductor wafer on a frame via an ultraviolet curing type dicing tape, and dicing the semiconductor wafer. Before, a step of slightly irradiating the ultraviolet-curable dicing tape with ultraviolet light, and a dicing method including a dicing step of performing dicing in a state where the adhesive of the ultraviolet-curable dicing tape is slightly cured, and At least, a step of disposing a semiconductor wafer on a frame via an ultraviolet-curing dicing tape, and a step of storing the semiconductor wafer disposed on the frame in a cassette and mounting the semiconductor wafer on a cassette mounting area of a dicing apparatus. Unloading the semiconductor wafers placed on the frame from the cassette and performing dicing. A step of slightly irradiating the ultraviolet-curable dicing tape with ultraviolet light during the dicing step, and a dicing step of performing dicing in a state where the adhesiveness of the ultraviolet-curable dicing tape is slightly cured. Things.

Further, after the dicing step is completed, a step of sufficiently irradiating the ultraviolet curing type dicing tape with ultraviolet rays to sufficiently lower the adhesive force is included. In the step of slightly irradiating the ultraviolet rays, an adhesive conforming to JIS Z0237 is used. The additional requirement that the force be reduced to approximately 1200 g / 25 mm is included.

Before the dicing of the semiconductor wafer, the step of slightly irradiating the ultraviolet-curable dicing tape with ultraviolet light is included, whereby the adhesive force of the ultraviolet-curable dicing tape is reduced, and the flexibility is also reduced. As a result, chipping does not occur around the groove on the surface (back surface) of the semiconductor wafer that is bonded to the tape during cutting, and chip quality can be improved.

Further, since the ultraviolet-curing dicing tape is slightly hardened, chatter vibration due to dicing is small, chipping hardly occurs around a cutting groove formed on the surface of the semiconductor wafer, and chip quality is reduced. Can be further improved.

Further, a step of unloading the semiconductor wafer disposed on the frame from the cassette and slightly irradiating the ultraviolet-curable dicing tape with ultraviolet light until the dicing is carried out includes a step of performing a series of steps. In this case, slight irradiation of ultraviolet light can be efficiently performed.

[0024]

Next, an embodiment of the present invention will be described in detail with reference to the flowchart shown in FIG. In implementing the dicing method according to the present invention, since the dicing apparatus 20 described in the related art can be used as it is, description will be given with reference to FIGS.

Semiconductor wafer 1 to be diced
0 is disposed on the frame 12 via the ultraviolet curing type dicing tape 11 as shown in FIG.
1) The frame 12 is stored in the cassette mounting area 22 with about 25 sheets stored in the cassette 21 (step ST2). Then, the frame 12 housed in the cassette 21 placed in the cassette placement area 22 is carried out to the frame area 24 by the wafer carrying-in / out means 23 (step ST3).

Next, the frame 12 holding the semiconductor wafer 10 is attracted to the first transfer means 25, and the first transfer means 25 pivots to rotate the chuck table 2.
6, the frame 12 is sucked and held. However, when the ultraviolet irradiation unit 31a is provided, the frame 12 is rotated when the first transfer unit 25 is turned, that is, the frame 12 is
After being unloaded from 1 and before being transported to the chuck table 26, it is positioned above the ultraviolet irradiation unit 31a, and can be irradiated with ultraviolet light at this time (step ST4).

The ultraviolet curing type dicing tape 11 is
By sufficiently irradiating ultraviolet rays, for example, 2400 g / g in an adhesive force measurement according to JIS Z0237.
The adhesive strength of 25 mm is reduced to 30 g / 25 mm, and the flexibility is also reduced accordingly.

Therefore, by slightly irradiating the ultraviolet rays, the adhesive force of the ultraviolet-curable dicing tape 11 is slightly reduced to approximately 1200 g / 25 mm by an adhesive force measurement according to JIS standard JIS Z0237, and the flexibility is also improved. The temperature is lowered and appropriately cured, and the holding state of the semiconductor wafer 10 is stabilized.

After the irradiation of the ultraviolet rays, the frame 12 holding the semiconductor wafer 10 is transferred to the chuck table 26 by the revolving movement of the first transfer means 25 and is held by suction (step ST5). Then, the semiconductor wafer 10 is positioned immediately below the alignment means 27 by the movement of the chuck table 26, the street is detected by image processing such as pattern matching, and precise alignment (alignment) with the cutting blade 28 is performed. The semiconductor wafer 10 on which the alignment is performed is subjected to the action of the cutting blade 28 by the movement of the chuck table 26, and the street is cut and diced (step ST6).

The semiconductor wafer 10 from which all the streets have been cut in this way is divided into rectangular shapes as shown in FIG. 3 to become individual chips.

When the ultraviolet irradiation unit 31b is provided, the semiconductor wafer 10 cannot be irradiated with ultraviolet rays in the course of the transfer by the first transfer means 25. There is a need. Note that, as the ultraviolet irradiation transfer means, the ultraviolet irradiation transfer means 40 shown in the prior art can be used as it is, and therefore, will be described with reference to FIG.

In order to irradiate the ultraviolet ray to the ultraviolet curing type dicing tape 11 holding the semiconductor wafer 10 by the ultraviolet irradiating unit 31b, first, it is taken out of the cassette 21 by the wafer carrying-in / out means 23 and placed in the frame area 24. The suction unit 45 is moved to a position directly above the semiconductor wafer 10, and the vertical moving unit 44 is lowered to hold the semiconductor wafer 10 by the suction unit 45, and the vertical moving unit 44 is raised.

Then, the conveying section 43 is slid in the P direction while holding the semiconductor wafer 10 by suction, and when the semiconductor wafer 10 is positioned directly above the ultraviolet irradiation unit 31b, ultraviolet curing dicing for holding the semiconductor wafer 10 is performed. UV light is slightly applied to the application tape 11 (step ST4). After the irradiation of the ultraviolet rays, the transport unit 43 is slid again in the Q direction to move the frame 12 directly above the frame region 24.
, The vertical moving unit 44 is lowered, the suction by the suction unit 45 is released, and the frame 12 is placed on the frame area 24.

Thereafter, the frame 12 is sucked and held on the chuck table 26 by turning the first transfer means 25 in the same manner as described above (step ST5), and dicing is performed in the same procedure as described above (step ST5).
6).

When dicing is completed, the chuck table 26 returns to the position where the semiconductor wafer 10 has been transferred by the first transfer means 25 before dicing. Then, the suction force of the chuck table 26 is released, and the frame 12 holding the semiconductor wafer 10 is transported by the second transporting means 29 to the cleaning / spin drying area 30, where it is cleaned and dried.

Note that, even after the semiconductor wafer 10 is divided into individual chips, each chip is still held on the frame 12 via the ultraviolet-curing dicing tape 11. The semiconductor wafer 10 does not fall apart due to the adhesive force.
The shape before dicing is maintained as a whole. Therefore, the individual chips are coated with an ultraviolet-curable dicing tape 1
By sufficiently irradiating the ultraviolet-curable dicing tape 11 with ultraviolet rays before being separated and picked up from the substrate 1, the adhesive force is sufficiently reduced, and chips can be picked up smoothly (step ST7). The irradiation of the ultraviolet rays here can be performed by the same method as in the conventional example.

After the irradiation with the ultraviolet rays, the frame 12 holding the semiconductor wafer 10 via the ultraviolet-curing dicing tape 11 having a reduced adhesive force is housed in a predetermined position of the cassette 21 by the carrying-in / out means 23 (step). ST
8).

The individual chips formed by dicing as described above were irradiated with a slight amount of ultraviolet light before cutting to harden the flexibility and stabilize the holding state of the semiconductor wafer 10, and then cut. As compared with the chip 50 formed by the conventional dicing method shown in FIG. 7, like the chip 13 shown in FIG. 4, the surface (back surface) bonded to the ultraviolet-curing dicing tape 11 has
Chipping is reduced.

Further, since the holding state of the semiconductor wafer 10 is stabilized, chatter vibration during dicing is small,
Chipping hardly occurs around the cutting groove formed on the surface of the semiconductor wafer 10.

[0040]

As described above, the dicing method according to the present invention provides a method for dicing a semiconductor wafer before dicing.
By including the step of slightly irradiating the UV-curable dicing tape with UV light, the adhesive strength of the UV-curable dicing tape is slightly reduced, and as a result, the flexibility is also reduced and hardened. Fine chipping (chipping) does not occur around the groove on the surface (back surface) of the wafer that is bonded to the tape, and the quality of the chip can be improved. Therefore, when the chip is packaged, cracking and cracking due to intermittent current due to ON / OFF do not occur.

Further, a step of unloading the semiconductor wafer disposed on the frame from the cassette and slightly irradiating the ultraviolet-curing type dicing tape with ultraviolet light until the dicing is performed is included. In this case, slight irradiation of ultraviolet light can be efficiently performed, and chip productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an embodiment of a dicing method according to the present invention.

FIG. 2 is an explanatory diagram showing a holding state of a semiconductor wafer to be cut by the dicing method.

FIG. 3 is an explanatory diagram showing a state of a semiconductor wafer after cutting by the dicing method.

FIG. 4 is an explanatory diagram showing a state of a chip formed by cutting by the dicing method.

FIG. 5 is a perspective view showing a generally used dicing apparatus for cutting a semiconductor wafer.

FIG. 6 is a perspective view of only an essential part showing an ultraviolet irradiation unit and a conveyance means for ultraviolet irradiation provided in a dicing apparatus for cutting a semiconductor wafer which is generally used.

FIG. 7 is an explanatory view showing a state of a chip formed by cutting by a conventional dicing method.

[Explanation of symbols]

Reference Signs List 10: semiconductor wafer 11: ultraviolet curing type dicing tape 12: frame 13: chip 14: chipping 20: dicing apparatus 21: cassette 22: cassette mounting area 23: carry-in / out means 24: frame area 25: first transport means 26: chuck table 27: alignment means 2
8: Blade 29: Second transport means 30: Cleaning and spin-drying area 31a, 31b: Ultraviolet irradiation unit 40: Ultraviolet irradiation transport means 42: Base 43: Transport unit 44: Vertical moving unit 45: Suction unit 50: Chip 51: Chipping

Claims (4)

[Claims] At least a step of arranging a semiconductor wafer on a frame via an ultraviolet-curable dicing tape, and slightly irradiating the ultraviolet-curable dicing tape with ultraviolet light before dicing the semiconductor wafer. A dicing method, comprising: a step of performing dicing in a state where the adhesiveness of the ultraviolet-curable dicing tape is slightly cured. 2. A process for disposing at least a semiconductor wafer on a frame via an ultraviolet-curing dicing tape, storing the semiconductor wafer disposed on the frame in a cassette, and disposing the semiconductor wafer in a cassette mounting area of a dicing apparatus. Placing the semiconductor wafer disposed on the frame from the cassette, and irradiating the ultraviolet-curable dicing tape with a small amount of ultraviolet light until dicing is performed; and A dicing step of performing dicing in a state where the adhesiveness of the mold dicing tape is slightly cured. 3. The dicing method according to claim 1, further comprising a step of sufficiently irradiating the ultraviolet-curable dicing tape with ultraviolet rays after the dicing step is completed to sufficiently reduce the adhesive strength. 4. The method according to claim 1, wherein the step of slightly irradiating the ultraviolet rays is performed according to JIS.
Adhesive force according to Z0237 is approximately 1200g / 25m
m, which is reduced to m.
4. The dicing method according to 2 or 3.