JP2021048151A - Wafer processing method - Google Patents

Abstract

To provide a wafer processing method that can prevent a device chip from scattering from a dicing table and prevent deterioration in quality of the device chip.SOLUTION: A wafer processing method includes at least a wettability enhancing step of irradiating a back surface 2b of a wafer 2 with ultraviolet rays to enhance the wettability of the back surface 2b of the wafer 2, a dicing tape sticking step of sticking a dicing tape 10 having an ultraviolet curable adhesive layer onto the back surface 2b of the wettability-enhanced wafer 2, an adhesive layer curing step of slightly applying ultraviolet rays from the dicing tape 10 side to slightly cure the adhesive layer, and a dividing step of positioning a cutting blade 20 at a front surface 2a of the wafer 2 and cutting planned division lines 4 to divide the wafer into individual device chips.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for processing a wafer in which a plurality of devices are partitioned by a scheduled division line and a wafer formed on the surface is divided into individual device chips.

A wafer in which a plurality of devices such as ICs and LSIs are partitioned by a planned division line and formed on the front surface is divided into individual device chips by a dicing device after the back surface is ground by a grinding device to form a desired thickness. , Each divided device chip is used for electric devices such as mobile phones and personal computers.

A dicing tape having an ultraviolet curable adhesive layer is attached to the back surface of the wafer before the wafer is transported to the dicing device, and the peripheral edge of the dicing tape is attached to a frame having an opening for accommodating the wafer. To. Thereby, the wafer is supported by the frame via the dicing tape (see, for example, Patent Document 1).

Then, the wafer supported by the frame is held by the chuck table of the dicing device and divided into individual device chips by a rotating cutting blade.

After that, the dicing tape is irradiated with ultraviolet rays, and the device chip is picked up from the dicing tape whose adhesive strength is reduced due to the curing of the adhesive layer.

Japanese Unexamined Patent Publication No. 11-3330011

However, if the size of the device chip is as small as 1 mm square or less (for example, 0.03 mm square, thickness 0.02 mm), the device chip moves on the adhesive layer of the dicing tape when dicing the wafer, and the device chip There is a problem that the outer circumference is chipped and the quality is deteriorated.

Further, although the movement of the device chip on the adhesive layer of the dicing tape can be suppressed by slightly irradiating the dicing tape with ultraviolet rays to cure the adhesive layer, the device chip is peeled off from the adhesive layer of the dicing tape due to the decrease in adhesive strength. There is a problem that it scatters.

An object of the present invention made in view of the above facts is to provide a method for processing a wafer, which can prevent the device chip from scattering from the dicing tape and can prevent the quality of the device chip from deteriorating. Is.

The present invention provides the following wafer processing method in order to solve the above problems. That is, it is a method of processing a wafer in which a plurality of devices are divided by a planned division line and the wafer formed on the front surface is divided into individual device chips. The back surface of the wafer is irradiated with ultraviolet rays to improve the wettability of the back surface of the wafer. A step of improving wettability, a step of sticking a dicing tape having a dicing tape having an ultraviolet curable adhesive layer on the back surface of a wafer with improved wettability, and a step of slightly irradiating ultraviolet rays from the dicing tape side. A wafer processing method consisting of at least an adhesive layer curing step in which the adhesive layer is slightly cured and a dividing step in which a cutting blade is positioned on the surface of the wafer to cut a planned division line and divided into individual device chips. The present invention provides.

The method for processing a wafer of the present invention has a wettability improving step of irradiating the back surface of the wafer with ultraviolet rays to improve the wettability of the back surface of the wafer, and an ultraviolet curable adhesive layer on the back surface of the wafer with improved wettability. The dicing tape sticking process for sticking the dicing tape, the adhesive layer curing step for slightly curing the adhesive layer by slightly irradiating the dicing tape side with ultraviolet rays, and the planned division line by positioning the cutting blade on the surface of the wafer. Since it is composed of at least a division process of cutting and dividing the dicing tape into individual device chips, even if the dicing tape is slightly irradiated with ultraviolet rays in the adhesive layer curing process, it is necessary between the wafer and the dicing tape. Since the adhesive strength is maintained, it is possible to prevent the device chip from scattering from the dicing tape in the dividing process. Further, in the wafer processing method of the present invention, the adhesive layer is slightly cured to the extent that the movement of the device chip on the dicing tape is suppressed so that the outer periphery of the device chip is not chipped when the wafer is diced. , It is possible to prevent deterioration of the quality of the device chip.

The perspective view which shows the state which carries out the wettability improvement process. The perspective view which shows the state which carries out the dicing tape sticking process. The perspective view which shows the state which carries out the adhesive layer hardening process. The perspective view which shows the state which carries out the division process.

Hereinafter, preferred embodiments of the wafer processing method of the present invention will be described with reference to the drawings.

FIG. 1 shows a disc-shaped wafer 2 processed by the wafer processing method of the present invention. The wafer 2 of the illustrated embodiment is formed of silicon (Si). The surface 2a of the wafer 2 is divided into a plurality of rectangular regions by a grid-like division schedule line 4, and devices 6 such as ICs and LSIs are formed in each of the plurality of rectangular regions.

In the wafer processing method of the illustrated embodiment, first, a wettability improving step of irradiating the back surface 2b of the wafer 2 with ultraviolet rays to improve the wettability of the back surface 2b of the wafer 2 is carried out.

In the wettability improving step, as shown in FIG. 1, first, the wafer 2 is positioned above the ultraviolet irradiation device 8 with the front surface 2a of the wafer 2 facing upward and the back surface 2b facing downward. Next, the ultraviolet irradiation device 8 irradiates the back surface 2b of the wafer 2 with ultraviolet rays (for example, irradiation at an output of 100 W for about 1 to 2 minutes). As a result, organic substances and the like existing on the back surface 2b of the wafer 2 can be removed, and the wettability of the back surface 2b can be improved.

After carrying out the wettability improving step, as shown in FIG. 2, a dicing tape sticking step of sticking the dicing tape 10 having an ultraviolet curable adhesive layer on the back surface 2b of the wafer 2 having improved wettability is carried out. The peripheral edge of the dicing tape 10 of the illustrated embodiment is fixed to an annular frame 12 having an opening 12a capable of accommodating the wafer 2.

Since the dicing tape sticking step is carried out in a state where the wettability of the back surface 2b of the wafer 2 is improved, between the back surface 2b of the wafer 2 and the adhesive layer of the dicing tape 10 after the dicing tape sticking step is carried out. The adhesive strength is stronger than the adhesive strength when the dicing tape 10 is attached to the back surface 2b of the wafer 2 in a state where the wettability of the back surface 2b of the wafer 2 is not improved.

After carrying out the dicing tape sticking step, the adhesive layer curing step of slightly irradiating the dicing tape 10 side with ultraviolet rays to slightly cure the adhesive layer is carried out.

In the adhesive layer curing step, as shown in FIG. 3, the wafer 2 is first positioned above the ultraviolet irradiation device 8 with the wafer 2 facing upward and the dicing tape 10 facing downward. Next, a small amount of ultraviolet rays are irradiated from the ultraviolet irradiation device 8 (for example, irradiation at an output of 100 W for about 2 seconds), and the dicing tape 10 is used so that the outer periphery of the device chip is not chipped when the wafer 2 is diced. The adhesive layer of the dicing tape 10 is slightly cured to the extent that the movement of the device chip can be suppressed.

The adhesive force between the wafer 2 and the dicing tape 10 after the adhesive layer curing step is performed will be described. As described above, in the dicing tape attaching step, the dicing tape 10 is attached to the back surface 2b of the wafer 2 in a state where the wettability of the back surface 2b of the wafer 2 is improved, and the wettability of the back surface 2b of the wafer 2 is improved. The adhesive strength between the wafer 2 and the dicing tape 10 is stronger than when the dicing tape 10 is attached to the back surface 2b of the wafer 2 in the unfinished state. Further, in the adhesive layer curing step, if the adhesive layer of the dicing tape 10 is slightly cured by irradiation with ultraviolet rays, the adhesive force between the wafer 2 and the dicing tape 10 is slightly reduced. At this time, the adhesive strength between the wafer 2 and the dicing tape 10 after performing the adhesive layer curing step is such that the wettability of the back surface 2b of the wafer 2 is not improved, and the dicing tape 10 is applied to the back surface 2b of the wafer 2. The adhesive layer of the dicing tape 10 is slightly cured by irradiation with ultraviolet rays so that the adhesive strength between the wafer 2 and the dicing tape 10 when the wafer is attached is about the same. As a result, the required adhesive force is maintained between the wafer 2 and the dicing tape 10, so that it is possible to prevent the device chip from scattering from the dicing tape 10 in the division step described later.

After carrying out the adhesive layer curing step, a cutting step is carried out in which the cutting blade is positioned on the surface 2a of the wafer 2 and the scheduled division line 4 is cut and divided into individual device chips. The dividing step can be carried out using, for example, the dicing apparatus 14 shown in FIG. 4 in part.

The dicing device 14 includes a chuck table (not shown) that sucks and holds the wafer 2 and a cutting means 16 that cuts the wafer 2 that is sucked and held by the chuck table. The chuck table is rotatably configured and is movably configured in the X-axis direction indicated by the arrow X in FIG. The cutting means 16 includes a spindle 18 rotatably configured around the Y-axis direction (direction indicated by the arrow Y in FIG. 4) orthogonal to the X-axis direction, and an annular cutting blade fixed to the tip of the spindle 18. Includes 20 and. The plane defined by the X-axis direction and the Y-axis direction is substantially horizontal.

In the dividing step, first, the surface 2a of the wafer 2 is turned upward, and the wafer 2 is sucked and held on the upper surface of the chuck table. Next, the wafer 2 is imaged from above by the imaging means (not shown) of the dicing device 14, and the planned division line 4 of the wafer 2 is aligned in the X-axis direction based on the image of the wafer 2 captured by the imaging means. The planned division line 4 aligned in the X-axis direction is positioned below the cutting blade 20. Next, as shown in FIG. 4, the cutting edge of the cutting blade 20 rotated at high speed in the direction indicated by the arrow A is cut into the scheduled division line 4 aligned in the X-axis direction from the front surface 2a to the back surface 2b of the wafer 2. At the same time, the wafer 2 is cut along the scheduled division line 4 by machining and feeding the chuck table relative to the cutting means 16 in the X-axis direction. In FIG. 4, the portion where the wafer 2 is cut along the scheduled division line 4 is indicated by reference numeral 22.

Then, the cutting blade 20 was indexed and fed relative to the chuck table in the Y-axis direction by the distance of the planned division line 4 in the Y-axis direction, and the cutting of the wafer 2 was repeated to align the wafers in the X-axis direction. Wafer 2 is cut along all of the planned division lines 4. Further, after rotating the chuck table by 90 degrees, the wafer 2 is repeatedly cut while indexing and feeding, and the wafer 2 is cut along all of the grid-shaped division scheduled lines 4. As a result, the wafer 2 can be divided into device chips for each individual device 6.

As described above, in the wafer processing method of the illustrated embodiment, the dicing tape 10 having an ultraviolet curable adhesive layer is attached to the back surface 2b of the wafer 2 whose wettability is improved by irradiation with ultraviolet rays. In the layer curing step, even if the dicing tape 10 is slightly irradiated with ultraviolet rays to slightly cure the adhesive layer of the dicing tape 10, the required adhesion between the back surface 2b of the wafer 2 and the adhesive layer of the dicing tape 10 is required. Power is maintained. Therefore, in the wafer processing method of the illustrated embodiment, it is possible to prevent the device chip from scattering from the dicing tape 10 in the dividing step.

Further, in the wafer processing method of the illustrated embodiment, the dicing tape 10 is used to suppress the movement of the device chip on the dicing tape 10 so that the outer periphery of the device chip is not chipped when dicing the wafer 2. Since the adhesive layer is slightly cured, it is possible to prevent deterioration of the quality of the device chip.

2: Wafer 2a: Wafer front surface 2b: Wafer back surface 4: Divided line 6: Device 10: Dicing tape 20: Cutting blade

Claims (1)

It is a processing method of a wafer in which a plurality of devices are partitioned by a scheduled division line and the wafer formed on the surface is divided into individual device chips.
A wettability improving process that irradiates the back surface of the wafer with ultraviolet rays to improve the wettability of the back surface of the wafer.
A dicing tape sticking process in which a dicing tape having an ultraviolet curable adhesive layer is stuck on the back surface of a wafer with improved wettability, and a dicing tape sticking process.
An adhesive layer curing step in which the adhesive layer is slightly cured by slightly irradiating ultraviolet rays from the dicing tape side, and
A division process in which a cutting blade is positioned on the surface of the wafer to cut the planned division line and divide it into individual device chips.
Wafer processing method consisting of at least.

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