JP2008153348A - Wafer dividing method - Google Patents

Abstract

When a wafer is cut to divide it into devices, the back surface is prevented from being chipped.
A glass plate 1 and a back surface W2 of a wafer W are bonded via an adhesive layer 2a whose adhesive strength is reduced by receiving an external stimulus, and a division line to be cut from the front surface W1 side of the wafer W is cut. Then, the wafer W is divided into individual devices D, and after the glass plate 1 is removed, the devices D are picked up. Since the cutting is performed with the back surface W2 of the wafer W held by the glass plate 1, the vibration of the cutting blade 31a is absorbed by the glass plate 1 fixed to the back surface of the wafer W. Fine vibrations in the wafer are suppressed, and the wafer W is not chipped.
[Selection] Figure 1

Description

  The present invention relates to a method for dividing a wafer into individual devices.

  A wafer formed by dividing a plurality of devices such as ICs and LSIs on the surface by dividing lines is divided into individual devices by cutting the dividing lines and used for various electronic devices. A cutting device that performs cutting by cutting a cutting blade that rotates at a high speed into a planned dividing line of a wafer is used for cutting the planned dividing line (see, for example, Patent Document 1).

JP 2006-295050 A

  However, when a wafer is cut using a cutting blade and divided into individual devices, there is a problem in that chipping occurs in the cutting grooves and the quality of the device is degraded. In particular, in a wafer whose back surface is coated with a metal film, chipping is likely to occur on the back surface along the cutting grooves due to differences in cutting resistance between the semiconductor and the metal.

  In addition, in order to prevent the cutting blade from becoming clogged by reaching the metal film, a half-cut groove having a depth that does not reach the metal film is formed by the cutting blade, and then along the half-cut groove. In this case, however, there is a problem that the back surface of the wafer is chipped when the half cut groove is formed.

  Therefore, the problem to be solved by the present invention is to prevent the back surface from being chipped when cutting the division line in order to divide the wafer into devices.

  The present invention relates to a wafer dividing method for dividing a wafer having a device formed on a surface divided by a predetermined dividing line into individual devices, through an adhesive layer whose adhesive force is reduced by external stimulation. Through the wafer sticking process of sticking the glass plate and the backside of the wafer, the wafer holding step of holding the glass plate side on the chuck table of the cutting device, and the cutting of the planned dividing line by the cutting blade from the front side of the wafer The wafer is divided into individual devices, the glass plate is removed from the back side of the wafer by reducing the adhesive force by applying external stimulus to the adhesive layer, and the wafer is supported via the adhesive tape. Transfer process to transfer the wafer to the pick-up frame and the wafer supported by the pick-up frame Composed of a pickup step for picking up. Here, “through the cutting of the line to be divided” in the dividing step means to include both the case of dividing only by cutting and the case of dividing by cutting with laser light after cutting.

  Wafers to which this wafer dividing method is applied include wafers whose rear surfaces are coated with a metal film. In the dividing process, the wafer is divided into devices by cutting the line to be divided with a cutting blade, and after the half-cut groove is formed with the cutting blade on the line to be divided, laser light is irradiated along the half-cut groove. Thus, both cases of dividing a wafer into devices are included. Examples of the external stimulus include ultraviolet light and laser light.

  In the present invention, since the cutting is performed in a state where the back surface of the wafer is held by the glass plate, the vibration of the cutting blade is absorbed by the glass plate fixed to the back surface of the wafer. Vibration is suppressed, and chipping of the wafer does not occur.

  In the following, the present invention will be described with reference to FIG. A plurality of devices D are formed on the surface W1 of the wafer W to be divided shown in FIG. Further, the back surface W2 of the wafer W is coated with a metal film.

  As shown in FIG. 2, the adhesive 2 is dropped on one surface of the glass plate 1 having a thickness that can stably support the wafer W, and the entire surface is spread as shown in FIG. Thus, the adhesive layer 2a is formed. The pressure-sensitive adhesive layer 2a is made of a pressure-sensitive adhesive that decreases in adhesive strength when subjected to an external stimulus such as ultraviolet light or laser light. Moreover, the thing of the type from which adhesive force falls by heating can also be used.

  Next, as shown in FIG. 1 (B) and FIG. 3, the back surface W2 of the wafer W is adhered to the adhesive layer 2a, and the glass plate 1 and the back surface W2 of the wafer W are adhered via the adhesive layer 2a. (Wafer pasting process).

  The wafer W adhered to the glass plate 1 is held on the chuck table 30 of the cutting device 3 shown in FIG. 4, for example. At this time, as shown in FIG. 1C, the glass plate 1 side is held in a state of facing the chuck table 30, and the surface W1 of the wafer W is exposed (wafer holding step).

  In the cutting apparatus 3 shown in FIG. 4, the chuck table 30 that holds the wafer W and the cutting means 31 having the cutting blade 31a are relatively moved in the X-axis direction (machining feed direction), the Y-axis direction (index feed direction), It is configured to move in the Z-axis direction (cutting feed direction). In the illustrated example, the chuck table 30 is movable in the X-axis direction, and the cutting means 31 is movable in the Y-axis direction and the Z-axis direction.

  Above the movement path of the chuck table 30, alignment means 32 that detects the division line S formed on the surface of the wafer W is disposed. The alignment unit 32 includes an imaging unit 32 a that images the surface of the wafer W. The cutting means 31 has a configuration in which a cutting blade 31a is mounted on a rotatable spindle 31b.

  When the glass plate 1 adhered to the wafer is held by the chuck table 30, the chuck table 30 moves immediately below the imaging unit 32 a, the surface of the wafer W is imaged, and the dividing line to be cut by the alignment means 32. S (see FIG. 3) is detected, and alignment with the cutting blade 31a in the Y-axis direction is performed. As the chuck table 30 further moves in the + X direction and the cutting means 31 descends while the cutting blade 31a rotates at a high speed, the cutting blade is moved to the detected division line S as shown in FIG. 31a cuts and the division | segmentation scheduled line S is cut. Further, by sequentially cutting by moving the chuck table 30 in the X-axis direction while moving the cutting means 31 in the Y-axis direction by an interval between the adjacent planned division lines, all the planned division lines S in the same direction are all removed. To be cut. Further, the chuck table 30 is rotated by 90 degrees, and then the same cutting is performed, whereby all the lines to be divided are cut vertically and horizontally and divided into individual devices D (dividing step). At this time, all devices D are in a state of being stuck to the glass plate 1 via the adhesive layer 2a.

  Thus, by cutting with the glass plate 1 adhered to the back surface W2 of the wafer W, the vibration of the cutting blade 31a that rotates at high speed is absorbed by the glass plate 1, and therefore the back surface W2 of the wafer W is absorbed. Fine vibrations are suppressed. Therefore, the wafer W is not chipped.

  Next, as shown in FIG. 1D, an external stimulus such as ultraviolet light or laser light is applied to the glass plate 1 to reduce the adhesive strength of the adhesive layer 2a, and as shown in FIG. Then, the glass plate 1 is removed together with the adhesive layer 2a from the back surface of the device D maintaining the shape of the wafer W as a whole (glass plate removing step). In order to prevent the device D from falling apart after the glass plate 1 is removed, an adhesive tape or the like is previously applied to the surface W1 of the wafer W before the glass plate 1 is removed, as shown in FIGS. The protective member 4 is attached.

  In the device D in which the protective member 4 is adhered to the front surface W1 and the shape of the wafer W is maintained as a whole, the back surface is adhered to the adhesive tape T as shown in FIG. Since this adhesive tape T is attached so as to close the opening of the ring-shaped pickup frame F, the wafer W attached to the adhesive tape T is integrated with the pickup frame F via the adhesive tape T. And become supported. Then, as shown in FIGS. 1G and 7, when the protective member 4 is removed from the surface W1 of the wafer W, a plurality of devices D maintaining the shape of the wafer W are transferred to the pickup frame F ( Transfer process).

  Next, as shown in FIG. 1 (H), the adhesive tape T to which the device D is attached in the pickup device is held on the holding table 5, and the adhesive tape T is extended by pulling the frame F downward. And increase the spacing between adjacent devices. Then, the devices D are attracted and lifted one by one by the suction portion 6a at the tip of the arm portion 6, peeled off from the adhesive tape T, picked up, and all devices are accommodated in a case (not shown).

  In the dividing step shown in FIG. 1C, the dividing line S is completely cut by the cutting blade 31a. However, the cutting blade 31a is cut to the back surface of the wafer W as shown in FIG. The half-cut groove 7 that does not reach the metal film 9 coated on the back surface is formed by half-cutting, and then the laser beam 8a is irradiated from the irradiation head 8 to the half-cut groove 7 as shown in FIG. However, the metal film 9 may be divided by ablation processing. In this case, since the metal film 9 is not cut by the cutting blade 31a, the cutting blade 31a is not easily clogged.

  In the above example, the case where a wafer of a type whose back surface is coated with a metal film is divided has been described. However, the present invention can also be applied to a wafer that is not coated with a metal film.

  Furthermore, if the back surface of the divided wafer is subjected to plasma plasma etching after the glass plate removing step and before the transferring step, the bending strength can be further improved.

It is explanatory drawing which shows this invention in time series, (A) is a glass plate with which the adhesion layer was coat | covered, (B) is a wafer sticking process, (C) is a wafer holding process and a division | segmentation process, (D) is glass. A state in which the adhesive layer is externally stimulated in the plate removal step, (E) is a state in which the glass plate is removed from the wafer in the glass plate removal step, and (F) is a process in which the wafer is attached to the adhesive tape in the transfer step. A state, (G) shows a state in which the protective member is removed from the wafer in the transfer step, and (H) shows a pickup step. It is a perspective view which shows the state which coat | covers an adhesion layer on a wafer and a glass plate. It is a perspective view which shows the wafer stuck on the glass plate. It is a perspective view which shows an example of a cutting device. It is a perspective view which shows the state which adheres a protection member to a wafer. It is a perspective view which shows the state which sticks a wafer to an adhesive tape. It is a perspective view which shows the state which removes a protection member from the wafer affixed on the adhesive tape. It is a front view which shows the state which forms a half cut groove | channel on the surface of a wafer. It is a front view which shows the state which irradiates a laser beam along a half cut groove | channel.

Explanation of symbols

W: Wafer W1: Front surface S: Scheduled division line D: Device W2: Back surface T: Adhesive tape F: Pickup frame 1: Glass plate 2: Adhesive 2a: Adhesive layer 3: Cutting device 30: Chuck table 31: Cutting means 31a: Cutting blade 31b: Spindle 32: Alignment means 32a: Imaging unit 4: Protection member 5: Holding table 6: Arm unit 6a: Suction unit 7: Half cut groove 8: Irradiation head 8a: Laser light 9: Metal film

Claims (5)

A wafer dividing method for dividing a wafer in which a device is formed on a surface divided by lines to be divided into individual devices,
A wafer sticking step of sticking the glass plate and the back surface of the wafer through an adhesive layer whose adhesive strength is reduced by receiving an external stimulus;
A wafer holding step of holding the glass plate side on a chuck table of a cutting device;
A dividing step of dividing the wafer into individual devices through cutting of the line to be divided by a cutting blade from the surface side of the wafer;
A glass plate removing step of reducing external adhesive force to the adhesive layer and removing the glass plate from the back surface of the wafer;
A transfer step of transferring the wafer to a pickup frame that supports the wafer via an adhesive tape;
A wafer dividing method comprising a pickup step of picking up a device from a wafer supported by the pickup frame.   The method for dividing a wafer according to claim 1, wherein the wafer is a wafer whose back surface is coated with a metal film.   3. The wafer dividing method according to claim 1, wherein in the dividing step, the dividing line is cut by a cutting blade to divide the wafer into devices. 4.   3. The wafer according to claim 1, wherein, in the dividing step, a half cut groove is formed on the division planned line by a cutting blade, and then the wafer is divided into devices by irradiating laser light along the half cut groove. Split method.   5. The wafer dividing method according to claim 1, wherein the external stimulus is either ultraviolet light or laser light.

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