JP2010118506A - Wafer dividing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer dividing method capable of completely protecting a wafer surface and preventing foreign matter from adhering to the wafer surface.
A method for dividing a wafer in which a wafer having devices formed in regions divided by a predetermined division line formed in a lattice shape is divided into individual devices, wherein a liquid resin is applied to the surface of the wafer. A protective film coating step for coating the protective film, a groove forming step for forming a groove having a depth corresponding to the finished thickness of the device from the protective film side along a line to be divided of the wafer, and a top surface of the protective film. A protective member adhering step for adhering the protective member to the substrate, and a back surface grinding for dividing the wafer into individual devices by grinding the back surface of the wafer and exposing the grooves formed in the groove forming step to the back surface side of the wafer And a process.
[Selection] Figure 3

Description

  The present invention relates to a wafer dividing method for dividing a wafer having a plurality of devices formed on a surface thereof by dividing lines into individual devices.

  A wafer in which a plurality of devices such as ICs, LSIs, or solid-state image sensors are defined on the surface by dividing the line, and the back surface is ground to a desired thickness, and then the dividing line is cut by a cutting device. Thus, the devices are divided into individual devices, and the divided devices are widely used in various electronic devices such as mobile phones and personal computers.

  In recent years, as electronic devices become lighter and thinner, it has been desired to reduce the thickness of the device to several tens of μm or less. As a method of forming such a thin device, a groove corresponding to the finished thickness of the device is formed on the front surface side of the wafer, and then the wafer is ground by grinding the back surface of the wafer to expose the groove from the back surface side. A so-called first dicing method (dicing before grinding) for dividing into individual devices has been proposed in Japanese Patent Laid-Open No. 11-40520.

  However, if the line to be divided is cut with a cutting blade in order to form a groove on the surface of the wafer, there is a problem in that cutting waste adheres to the surface of the wafer and deteriorates the quality of the device.

  Even when a laser beam is irradiated to a division line by a laser processing apparatus to form a groove, the droplets melted and scattered upon irradiation with the laser beam adhere to the wafer surface, resulting in the same problem. In particular, when the device is a solid-state image sensor, it is very important to prevent the attachment of cutting waste because a device failure occurs due to the attachment of cutting waste.

As a method for solving such a problem, Japanese Patent Application Laid-Open No. 2007-165694 discloses a method in which a protective member is attached to the front surface side of a wafer, a groove is formed on the front surface side, and a groove is formed by grinding the back surface side. To divide the wafer into individual devices.
JP 11-40520 A JP 2007-165694 A

  However, in general, a plurality of structures such as electrodes are formed on the wafer surface, and it is difficult to attach a protective member without a gap between the wafer surface side and the protective member, and between the protective member and the wafer accompanying cutting. There is a problem that foreign matter enters.

  The present invention has been made in view of these points, and the object of the present invention is to completely protect the wafer surface and to divide the wafer so that foreign matter can be prevented from adhering to the wafer surface during surface cutting of the wafer. Is to provide a method.

  According to the present invention, there is provided a wafer dividing method for dividing a wafer in which devices are formed in regions partitioned by grid-formed division lines into individual devices, and applying a liquid resin to the surface of the wafer A protective film coating step for coating the protective film, a groove forming step for forming a groove having a depth corresponding to the finished thickness of the device from the protective film side along the planned dividing line of the wafer, A protective member adhering step for adhering a protective member on the upper surface, and a back surface for grinding the back surface of the wafer to expose the grooves formed in the groove forming step to the back surface side of the wafer to divide the wafer into individual devices And a grinding process. A method for dividing a wafer is provided.

  Preferably, the liquid resin is composed of a water-insoluble resin whose adhesive strength is reduced by ultraviolet irradiation, and the protective member is composed of a protective tape whose adhesive strength is not changed by ultraviolet irradiation. Then, the protective film is irradiated with ultraviolet rays through the protective member, and the protective film adhered to the protective member is peeled off from the wafer together with the protective member.

  According to the present invention, since a liquid resin is applied to the wafer surface and the wafer surface is covered with the protective film formed from the resin, no gap is formed between the structure on the wafer surface and the protective film. The surface is protected. As a result, it is possible to divide the wafer without foreign matter such as cutting chips adhering between the protective film and the wafer surface as the wafer is cut, and the yield can be improved.

  When the protective film is made of a water-insoluble resin whose adhesive strength is reduced by ultraviolet irradiation, and the protective member is made of a protective tape whose adhesive strength does not change by ultraviolet irradiation, the ultraviolet rays are irradiated after dividing the wafer. It becomes possible to remove the protective film and the protective tape integrally from the wafer surface. Therefore, the protective member removing step and the protective film removing step can be performed as one step, and productivity is improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer before being processed to a predetermined thickness. A semiconductor wafer 2 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm, and has a plurality of first streets (division planned lines) S1 on a surface 2a and a plurality of first streets orthogonal to the first streets S1. Two streets S2 are formed in a lattice shape, and devices 4 such as ICs, LSIs, solid-state image sensors, and the like are formed in a plurality of regions partitioned by the first and second streets S1 and S2.

  In the wafer dividing method of this embodiment, first, as a first step, a liquid resin is applied to the surface 2a of the wafer 2, and the surface of the wafer 2 is covered with a protective film 6 as shown in FIG. This liquid resin is preferably a water-insoluble resin whose adhesive strength is reduced by ultraviolet irradiation.

  In order to achieve the alignment of the cutting blade through the protective film 2, the protective film 6 is preferably transparent. When the protective film 6 is opaque, it is necessary to detect the streets S1 and S2 with an infrared CCD or the like during alignment.

  The liquid resin can be applied onto the surface 2a of the wafer 2 by, for example, a spin coating method. Since the protective film 6 of the present embodiment is formed of a resin, the surface 2a of the wafer 2 is completely formed without forming a gap between a structure such as an electrode formed on the wafer surface and the protective film 6. Can be protected.

  The wafer 2 having the protective film 6 formed on the surface 2a is sucked and held by the chuck table 10 of the cutting device 8 as shown in FIG. At this time, the back surface 2b side of the wafer 2 is sucked and held by the chuck table 10, and the protective film 6 is exposed.

  The chuck table 10 is movable in the horizontal direction (X-axis direction) in FIG. 3, and a cutting means 16 having a cutting blade 12 mounted on the spindle 14 is disposed above the movement path. Has been.

  The cutting means 16 is movable in the direction perpendicular to the paper surface (Y-axis direction) and the Z-axis direction in FIG. The cutting means 16 is fixed with an alignment means 18 for picking up and detecting the streets S1 and S2 formed on the surface 2a of the wafer 2 with an image pickup means 20 such as a CCD camera.

  When the chuck table 10 that sucks and holds the wafer 2 on which the protective film 6 is formed moves in the X-axis direction, the alignment unit 18 detects the street S1 or S2 to be cut.

  After completion of the alignment, the detected street S1 or S2 is cut by moving the chuck table 10 in the X-axis direction while rotating the cutting blade 12. At this time, as shown in FIG. 3, the cutting blade 12 cuts the protective film 6 completely, but does not cut the wafer 2 completely, but cuts it by an amount corresponding to the finished thickness of the device 4.

  The chuck table 10 moves in the X-axis direction to cut the first street S1, and further, the cutting means 16 is indexed in the Y-axis direction by the street interval to cut all the first streets S1 sequentially.

  Furthermore, when the same cutting is performed after the chuck table 10 is rotated by 90 degrees, the second street S2 is all cut, and the protective film 6 is cut vertically and horizontally as shown in FIGS. A groove 22 having a depth corresponding to the finished thickness of the device 4 is formed on the surface 2a of the wafer 2 along the first and second streets S1 and S2 (groove forming step).

  In the groove forming step, since the protective film 6 is formed on the surface 2a of the wafer 2, even if the cutting waste generated by the cutting of the wafer 2 is scattered, the protective film 6 causes the cutting waste on the surface of each device 4. Can be prevented, and the quality of the device 4 is not deteriorated.

  In this groove forming step, a liquid resin can be applied onto the surface 2a of the wafer 2 to cover the protective film 6, and the grooves 22 can be formed in the streets S1 and S2 by laser beam irradiation. In this case, even if the wafer material is melted and scattered by the irradiation of the laser beam, the protective film 6 can prevent the droplets from adhering to the surface of the wafer 2.

  Next, as shown in FIG. 6, the protective member 24 is attached to the surface of the protective film 6 without peeling off the divided protective film 6. The protective member 24 is preferably a protective tape whose adhesive force does not change when irradiated with ultraviolet rays. The protective member 24 is made of, for example, a pressure-sensitive protective tape, and is bonded by pressing with a roller.

  Then, as shown in FIG. 7, the wafer 2 having the protective member 24 adhered on the protective film 6 is turned over, and the protective member 24 side of the wafer 2 is sucked and held by the chuck table 28 of the grinding device 26 shown in FIG. . Thereby, the back surface 2b of the wafer 2 is exposed.

  A grinding device 26 shown in FIG. 8 includes a grinding means 36 configured by attaching a grinding wheel 34 to a lower end of a rotationally driven spindle 30 via a wheel mount 32. A grindstone 38 is fixed.

  While rotating the chuck table 28 at, for example, 300 rpm with respect to the wafer 2 held on the chuck table 28, the grinding wheel 34 is rotated in the same direction as the chuck table 28 at, for example, 6000 rpm, and a grinding means moving mechanism (not shown) is operated. Then, the grinding wheel 38 is brought into contact with the back surface 2 b of the wafer 2.

  Then, the grinding wheel 34 is ground and fed by a predetermined amount at a predetermined grinding feed rate (for example, 3 to 5 μm / second), and the wafer 2 is ground. As shown in FIG. 9, when grinding is performed until the groove 22 formed on the wafer 2 is exposed from the back surface side, adjacent devices are separated by the groove 22 penetrating the front and back surfaces of the wafer 2. Divided into 4 (back grinding process).

  According to the present embodiment, since the protective member 24 is adhered to the protective film 6, the device 4 is not separated even after the back surface grinding step and the groove 22 penetrates, and the wafer 2 as a whole. The shape is maintained.

  As described above, the liquid resin is composed of a water-insoluble resin whose adhesive strength is reduced by ultraviolet irradiation, and the protective member 24 is composed of a pressure-sensitive protective tape whose adhesive strength is not changed by ultraviolet irradiation.

  Therefore, after performing the back surface grinding process, the wafer 2 is removed from the chuck table 28, the wafer 2 is inverted, and the protective film 6 is irradiated with ultraviolet rays through the protective member 24, and the protective film adhered to the protective member 24. 6 can be peeled from the wafer 2 together with the protective member 24.

It is a surface side perspective view of a semiconductor wafer. It is a perspective view of a semiconductor wafer in the state where a protective film was covered. It is explanatory drawing which shows an example of a groove | channel formation process. It is a perspective view which shows the wafer and protective film after completion | finish of a groove | channel formation process. It is an expanded sectional view of FIG. It is a perspective view which shows a mode that a protective member is stuck on a protective film. It is a perspective view which shows the state by which the protection member was stuck on the protective film. It is explanatory drawing which shows an example of a back surface grinding process. It is a perspective view which shows the wafer after completion | finish of a back surface grinding process, a protective film, and a protection member.

Explanation of symbols

2 Semiconductor wafer 4 Device 6 Protective film 8 Cutting device 10 Chuck table 12 Cutting blade 22 Groove 24 Protective member 26 Grinding device 28 Chuck table 34 Grinding wheel 38 Grinding wheel

Claims (2)

A wafer dividing method for dividing a wafer in which devices are respectively formed in regions partitioned by division-scheduled lines formed in a lattice shape into individual devices,
A protective film coating step of coating a protective film by applying a liquid resin to the surface of the wafer;
A groove forming step of forming a groove having a depth corresponding to the finished thickness of the device along the planned dividing line of the wafer from the protective film side;
A protective member attaching step of attaching a protective member on the protective film;
Grinding the back surface of the wafer and exposing the groove formed in the groove forming step to the back side of the wafer to divide the wafer into individual devices; and
A method for dividing a wafer, comprising: The liquid resin is composed of a water-insoluble resin whose adhesive strength is reduced by ultraviolet irradiation,
The protective member is composed of a protective tape whose adhesive force does not change by ultraviolet irradiation,
2. The wafer dividing method according to claim 1, wherein the protective film is irradiated with ultraviolet rays through the protective member, and the protective film adhered to the protective member is peeled off from the wafer together with the protective member.

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