JP4697823B2 - Method for dividing brittle substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dividing method for dividing a brittle substrate such as a semiconductor wafer into individual chips.
[0002]
[Prior art]
Usually, a brittle substrate such as a semiconductor wafer is formed by cutting a street, which is a region to be cut, formed on a semiconductor wafer vertically and horizontally using a rotating blade provided in a dicing machine to form a cutting groove. It is divided into.
[0003]
However, when cutting with a rotating blade, chipping occurs on both sides of the cutting groove, so that the street needs to have a width of at least about 50 μm. Therefore, a circuit is formed by the area of the street. The effective area of the chip area is limited.
[0004]
Therefore, in order to secure as wide a chip area as possible to form a circuit, a technique of dividing into individual chips by irradiating the street with a laser beam instead of cutting with a rotating blade has been proposed.
[0005]
[Problems to be solved by the invention]
However, even if the street is irradiated with a laser beam, the breaking line is not always formed along the street, so that there is a problem in that the breaking region branches and damages the chip region. .
[0006]
Therefore, in the cleaving of the brittle substrate by the laser beam, there is a problem in accurately and surely cleaving without damaging the chip region.
[0007]
[Means for Solving the Problems]
As a specific means for solving the above problems, the present invention provides a brittle substrate using a cleaving apparatus having a holding means for holding the brittle substrate and a cleaving means for irradiating the brittle substrate held by the holding means with a laser beam. A dividing method of dividing into individual chips, wherein the holding means is composed of a chuck table that sucks and holds the brittle substrate, and a frame holding unit that holds a frame integrated with the brittle substrate via a holding tape, The chuck table is configured to selectively communicate with either the suction source or the air supply source via the switching valve, and the chuck table communicates with the suction source to chuck the brittle substrate integrated with the frame via the holding tape. frame while sucking and holding table fixed to a frame holding portion, as the area to be fractured in the area to be breaking the brittle substrate is not fractured And stress generation step you irradiating intensity of the laser beam, after the stress generation step is completed, the dividing step stress by irradiating again laser beam to the area to be fractured divides the brittle substrate along the area remaining In the splitting process, the chuck table is connected to an air supply source, air is sent to the chuck table holding the brittle substrate by suction, the brittle substrate is expanded into a spherical shape, and the area to be cleaved is cleaved. Provided is a method for dividing a brittle substrate by irradiating a region to be cleaved with a laser beam in a state where an external force is applied so that the surface on the side irradiated with a laser beam with a strength not to be applied is spread.
[0008]
And this brittle board | substrate division | segmentation method makes it an additional requirement that a brittle board | substrate is a semiconductor wafer and the area | region which should be cut | disconnected is the street formed in the lattice form in the semiconductor wafer.
[0009]
According to the brittle substrate dividing method configured in this way, by pre-stressing by irradiating the laser beam to the region to be cleaved, by irradiating the laser beam again to the region where the stress remains, Since the cleaving is performed due to the remaining stress, the cleaving line is not branched and the chip is not damaged. Further, since it is not necessary to use cutting water as in the case of dividing by cutting, the surface of the chip is not contaminated.
[0010]
In particular, in the dividing step, the stress is to perform the irradiation of the laser beam in a state in which spread surface towards remaining, it is possible to draw more of the cleaving ability of the stress remaining, the accuracy of the fracture is Increase.
[0011]
Furthermore, the line width of the laser beam is about 10 μm, and the line width of the region to be cleaved can be set to a few dozen μm correspondingly, so that, for example, in the case of a semiconductor wafer, a wide chip region can be secured. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
As an embodiment of the present invention, a case where a semiconductor wafer is divided into individual chips by using the cleaving apparatus 10 shown in FIG. 1 will be described as an example.
[0013]
In the cleaving apparatus 10 of FIG. 1, a plurality of semiconductor wafers W to be divided are accommodated in a cassette 11 in a state of being integrated with a frame F via a holding tape T, and are placed in a temporary placement region 13 by a loading / unloading means 12. After being carried out, it is conveyed to the holding means 15 by the conveying means 14.
[0014]
The holding means 15 is generally composed of a chuck table 16 that holds the semiconductor wafer W by suction and a frame holding portion 17 that holds the frame F.
[0015]
As shown in FIG. 2, on the surface of the semiconductor wafer W, streets S, which are regions to be cleaved, are formed in a lattice pattern at predetermined intervals, and in a large number of chip regions C partitioned by the streets S, A circuit pattern is applied. The semiconductor wafer W is sucked and held by the chuck table 16 and held by the holding means 15 by fixing the frame F to the frame holding portion 17.
[0016]
1, the holding means 15 holding the semiconductor wafer W moves in the + X direction and is positioned immediately below the imaging means 19 constituting the alignment means 18, where the surface of the semiconductor wafer W is here. Are picked up and the streets to be cut are detected.
[0017]
Further, a cleaving means 20 is disposed in the vicinity of the alignment means 18 in the + X direction, and the cleaving means 20 is provided with an irradiation unit 21 for irradiating a laser beam downward.
[0018]
When the street to be cleaved is detected by the alignment means 18 and the detected street and the irradiation unit 21 are aligned in the Y-axis direction, the holding means 15 further moves in the + X direction, as shown in FIG. The street is positioned immediately below the irradiation unit 21, and the laser beam 30 having an appropriate intensity is irradiated from the irradiation unit 21 to the street while the holding unit 15 moves in the + X direction. The laser beam 30 irradiated here is strong enough to prevent the street from being cleaved. When the laser beam is irradiated in this way, stress is generated on the street and remains.
[0019]
Then, by reciprocating the holding means 15 in the X-axis direction while indexing and feeding the cleaving means 20 in the Y-axis direction by the street interval, stress is generated and remains in all streets in the same direction.
[0020]
Further, after rotating the holding means 15 by 90 degrees, similarly to the above, the holding means 15 is reciprocated in the X-axis direction, and a laser beam having an appropriate intensity is irradiated while indexing and feeding the cleaving means 20 in the Y-axis direction. As a result, stress is generated in all the streets formed in a lattice shape and remains (stress generation step).
[0021]
When irradiating a laser beam having an appropriate intensity, the chuck table 16 communicates with the suction source 23 via the switching valve 22, so that the semiconductor wafer W is sucked in close contact with the surface of the chuck table 16. Is retained.
[0022]
When stress remains in all the streets as described above, next, by irradiating the laser beams 31 to all the streets again, the streets are completely cleaved along the streets where the stress remains, Divide into individual chips (dividing step).
[0023]
In this way, the stress is generated and left in the stress generation process, and then irradiated again with the laser beam, so that the cutting is performed along the area where the stress remains and is completely divided. Cleaving is performed accurately and reliably without branching, and the chip is not damaged.
[0024]
Further, unlike the case of cutting, since cutting water is not used, the surface of the chip is not contaminated, and the quality of the chip can be improved.
[0025]
Furthermore, the line width of the laser beam is sufficient to be around 10 μm, and the line width of the region to be cleaved can be correspondingly increased to several tens of μm, so that a wide chip region can be secured. Therefore, since the number of chips formed from one semiconductor wafer can be increased, productivity can be improved and yield can be improved.
[0026]
When performing the dividing step, as shown in FIG. 4, by switching the switching valve 22, the chuck table 16 and the air supply source 24 are communicated to send air to the chuck table 16, and the semiconductor wafer W is moved to the spherical surface. It is preferable that the stress be expanded outward by expanding the shape.
[0027]
Then, if the dividing step is performed in that state, the street remains and is guided by the stress acting on the outside, and the street is cleaved accurately and reliably and divided into individual chips.
[0028]
In this way, by performing the dividing step so that the stress spreads outward, it is possible to further extract the cleaving ability of the accumulated stress, so that the accuracy is further increased and the quality of the chip is further improved.
[0029]
Note that although the case where the semiconductor wafer is cleaved is described as an example in this embodiment, the workpiece to be cleaved is not limited to this.
[0030]
【The invention's effect】
As described above, according to the method for dividing a brittle substrate according to the present invention, the stress is accumulated in advance by irradiating the region to be cleaved with the laser beam, and the region where the stress remains is irradiated again. By doing so, since the cleaving is performed due to the remaining stress, the cleaving line does not branch and damage the chip, and the quality of the chip can be improved. Moreover, since it is not necessary to use cutting water as in the case of dividing by cutting, the surface of the chip is not contaminated, and the quality of the chip can also be improved in this respect.
[0031]
In particular, in the dividing process, when the laser beam irradiation is performed in a state where the surface where the stress remains is widened, the cleaving ability of the remaining stress can be further extracted. Increases accuracy and improves chip quality.
[0032]
Furthermore, the line width of the laser beam is about 10 μm, and the line width of the region to be cleaved can be set to a few dozen μm correspondingly, so that, for example, in the case of a semiconductor wafer, a wide chip region can be secured. . Therefore, since the number of chips formed from one semiconductor wafer can be increased, productivity can be improved and yield can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a cleaving apparatus used for carrying out a brittle substrate dividing method according to the present invention.
FIG. 2 is a perspective view showing a state in which a semiconductor wafer is held by holding means constituting the cleaving apparatus.
FIG. 3 is an explanatory view showing a stress generating step constituting the brittle substrate dividing method according to the present invention.
FIG. 4 is an explanatory view showing a dividing step constituting the method for dividing the brittle substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cleaving apparatus 11 ... Cassette 12 ... Carry-in / out means 13 ... Temporary placing area 14 ... Conveyance means 15 ... Holding means 16 ... Chuck table 17 ... Frame holding part 18 ... Alignment means 19 ... Imaging means 20 ... Cleaving means 21 ... Irradiation part 22 ... Switching valve 23 ... Suction source 24 ... Air supply source 30, 31 ... Laser beam

Claims (2)

A dividing method of dividing a brittle substrate into individual chips using a cleaving apparatus having a holding means for holding a brittle substrate and a cleaving means for irradiating the brittle substrate held by the holding means with a laser beam ,
The holding means includes a chuck table for sucking and holding the brittle substrate, and a frame holding unit for holding a frame integrated with the brittle substrate via a holding tape. The chuck table is connected via a switching valve. Configured to selectively communicate with either the suction source or the air supply source,
The chuck table and fixed to the frame holding section the frame with the brittle substrate which is integral with said frame via the retaining tape is communicated to the suction source to the suction held by the chuck table, breaking of the brittle substrate and stress generated process zone should該割cross the should do area you irradiation intensity of the laser beam so as not be fractured,
After the stress generation step is completed, the region to be cleaved is again irradiated with a laser beam to divide the brittle substrate,
In the dividing step, the chuck table is communicated with the air supply source, air is sent to the chuck table holding the brittle substrate by suction, the brittle substrate is expanded into a spherical shape, and the region to be cleaved is A method for dividing a brittle substrate in which an area to be cleaved is irradiated with a laser beam in a state where an external force is applied so that the surface irradiated with the laser beam having a strength that is not cleaved is spread.   2. The method for dividing a brittle substrate according to claim 1, wherein the brittle substrate is a semiconductor wafer, and the region to be cleaved is a street formed in a lattice shape on the semiconductor wafer.

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