JP2011061144A - Supporting sheet for object to be processed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supporting sheet for an object to be processed, without reducing the number of devices to be adopted, as well as, increasing the number. <P>SOLUTION: The support sheet for the object to be processed is adhered on one side of the object to be processed and supports the object to be processed, and the support sheet includes: a sheet substrate; a layer for sticking which is formed on the sheet substrate and adhered to the object to be processed; and an annular reinforcing member integrated with the sheet substrate at an outer circumferential side of the sheet substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a workpiece support sheet that is bonded to one surface of a workpiece and supports the workpiece.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. A dividing line is cut by a cutting device (dicing device) to be divided into individual devices, and the divided devices are widely used in electric devices such as mobile phones and personal computers.

  A grinding apparatus for grinding the back surface of a semiconductor wafer includes a chuck table for holding the wafer, and a grinding means on which a cutting wheel having a grinding wheel for grinding the wafer held on the chuck table is rotatably mounted. The wafer can be ground to a desired thickness with high accuracy.

  When grinding the backside of a wafer with a grinding machine, the surface side of the wafer on which a large number of devices are formed must be sucked and held with a chuck table, so that a protective tape is applied to the surface of the wafer so as not to damage the device. Grinding is performed (see, for example, JP-A-5-198542).

  On the other hand, along with the recent miniaturization and thinning of electrical equipment, various semiconductor devices are also becoming lighter and thinner, and semiconductor wafers are required to be thinly ground to, for example, 30 μm or less.

JP-A-5-198542

  However, in a semiconductor wafer thinly ground to, for example, 30 μm or less, there is a problem that warpage is greatly generated due to stress remaining in a device formed on the surface side or distortion caused by grinding, and the wafer is warped together with the protective tape. appear. If the semiconductor wafer is warped, handling becomes difficult and the semiconductor wafer may be damaged.

  Therefore, in order to prevent the warpage of the semiconductor wafer, the applicant of the present application grinds and thins only the central portion of the back surface of the semiconductor wafer disclosed in Japanese Patent Application Laid-Open No. 2007-19461, so that the outer periphery of the semiconductor wafer is obtained. The processing method which made a part remain | survive as an annular convex part and made it a reinforcement part was proposed.

  However, in this method, since the outer peripheral portion of the semiconductor wafer is left without being ground and used as a reinforcing portion, a device cannot be formed just to the outer periphery of the wafer, and the number of devices per semiconductor wafer is limited. The problem arises. Further, in the cutting process after the back surface grinding, it is necessary to remove the reinforcing portion remaining at the time of cutting, and there is a problem that the number of man-hours increases.

  The present invention has been made in view of these points, and an object of the present invention is to provide a support sheet for a workpiece without reducing the number of devices and without increasing the number of processing steps. It is.

  According to the present invention, there is provided a support sheet for a workpiece that is bonded to one surface of a workpiece and supports the workpiece, the sheet substrate, and a glue that is formed on the sheet substrate and adheres to the workpiece. There is provided a support sheet for a workpiece, comprising: a layer; and an annular reinforcing member integrated with the sheet base material on an outer peripheral side of the sheet base material.

  Preferably, the sheet base material is composed of any one of polyolefin, polyvinyl chloride, and polyethylene terephthalate, and the glue layer is composed of a glue layer whose adhesive strength is reduced by an external stimulus such as ultraviolet irradiation or heating. The annular reinforcing member is formed of any one of wire, plastic, and carbon.

  According to the present invention, since the annular reinforcing member is fixed and integrated on the outer peripheral portion of the sheet base material, it is integrated with the support sheet even if the entire surface of the workpiece such as a semiconductor is ground and thinned. The annular reinforcing member can be supported flat without causing warpage.

  Therefore, handling of the workpiece is facilitated and damage is prevented. Moreover, since it is not necessary to form a reinforcement part in workpiece itself, the process of removing a reinforcement part later can be made unnecessary, without reducing the number of devices.

  Furthermore, when the support sheet of the present invention is used as a dicing tape at the time of the cutting process, it is necessary to separately attach the support sheet to the annular frame because the annular reinforcing member is integrally formed on the disk-shaped sheet base material. There is no.

  Therefore, the tension of the dicing tape is increased by lowering the annular frame, which has been a problem with the conventional support by the dicing tape and the annular frame, and back surface cracks that occur when the tension is released by cutting can be prevented.

  As in the second aspect of the invention, by making the outer size of the workpiece equal to the outer size of the annular reinforcing member, a conventional grinding apparatus and a cassette that accommodates the wafer can be shared.

It is a surface side perspective view of a semiconductor wafer. It is a perspective view which shows a mode that the support sheet of this invention is stuck on the surface of a semiconductor wafer. FIG. 3A is a cross-sectional view of a state in which the support sheet of the first embodiment of the present invention is attached to the surface of the semiconductor wafer, and FIG. 3B is a perspective view thereof. 4A is a cross-sectional view of a state in which the support sheet of the second embodiment is attached to the surface of the semiconductor wafer, and FIG. 4B is a cross-sectional view of a state in which the support sheet of the third embodiment is attached. It is. It is sectional drawing of the state by which the support sheet of 4th Embodiment of the same size as the external shape of a semiconductor wafer was stuck on the surface of the semiconductor wafer. It is a perspective view which shows the positional relationship of the grinding wheel at the time of a grinding process, and the semiconductor wafer hold | maintained at the chuck table. It is a perspective view which shows the conventional support form which supports a semiconductor wafer with a cyclic | annular flame | frame via a dicing tape.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front perspective view of a semiconductor wafer suitable for supporting with the support sheet of the present invention during back grinding. The semiconductor wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm. A plurality of streets (division lines) 13 are formed in a lattice shape on the surface 11a. A device 15 such as an IC or LSI is formed in each partitioned area.

  The semiconductor wafer 11 configured as described above includes a device region 17 where the device 15 is formed and an outer peripheral surplus region 19 surrounding the device region 17 on a flat portion of the surface. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  Before such a semiconductor wafer 11 is cut by a cutting device and divided into individual semiconductor devices, the back surface 11b of the semiconductor wafer 11 must be ground and thinned by a grinding device.

  At the time of grinding, since the surface 11a side of the semiconductor wafer 11 is sucked and held by the chuck table of the grinding apparatus, a protective member is provided on the surface 11a of the wafer 11 to protect the device 15 on the surface 11a of the wafer 11 as shown in FIG. A support sheet 23 is attached.

  FIG. 3A shows a cross-sectional view of a state in which the support sheet 23 of the first embodiment of the present invention is attached to the surface 11 a of the semiconductor wafer 11. FIG. 3B is a perspective view thereof. The support sheet 23 includes a disk-shaped sheet substrate 2, a glue layer 4 formed on the sheet substrate 2 and bonded to the wafer 11, and an annular reinforcing member embedded in the outer peripheral portion of the disk-shaped sheet substrate 2. 6. As is apparent from the figure, the support sheet 23 has a diameter slightly larger than the diameter of the semiconductor wafer 11.

  The sheet substrate 2 is formed from any of polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer 4 is preferably made of an acrylic resin, for example, and preferably has a property that the adhesive strength is reduced by an external stimulus such as ultraviolet irradiation or heating. On the other hand, the annular reinforcing member 6 is formed of any one of wire, plastic, and carbon.

  Referring to FIG. 4A, a cross-sectional view of a state in which the support sheet 23 </ b> A of the second embodiment of the present invention is attached to the surface 11 a of the semiconductor wafer 11 is shown. In the support sheet 23 </ b> A of the present embodiment, the annular reinforcing member 8 is fixed on the surface of the disk-shaped sheet base material 2 so as to surround the semiconductor wafer 11. Since the other configuration of the sheet base material 23A of the present embodiment is the same as that of the sheet base material 23 of the first embodiment described above, description thereof is omitted.

  Referring to FIG. 4B, a cross-sectional view of the third embodiment of the present invention in which the support sheet and 23B are attached to the surface 11a of the semiconductor wafer 11 is shown. In the support sheet 23 </ b> B of the present embodiment, the annular reinforcing member 10 is fixed to the back surface of the disc-shaped sheet substrate 2. Since the other structure of the support sheet 23B of this embodiment is the same as that of the support sheet 23 of 1st Embodiment mentioned above, the description is abbreviate | omitted.

  Referring to FIG. 5, there is shown a cross-sectional view of a state in which the support sheet 23 </ b> C of the fourth embodiment of the present invention is adhered to the surface 11 a of the semiconductor wafer 11. The support sheet 23C of this embodiment is similar to the support sheet 23 of the first embodiment shown in FIG. 3, and the difference is that the diameter of the support sheet 23C is substantially the same as the diameter of the semiconductor wafer 11.

  Thus, by making the outer shape size of the annular reinforcing member 6 and the outer size size of the semiconductor wafer 11 substantially the same, the structure of a chuck table of a conventional grinding apparatus, a suction pad of a conveying means, or a cassette that accommodates a wafer is provided. The support sheet 23C of the present embodiment can be used without any change.

  Next, a grinding operation for attaching the support sheet 23C of the fourth embodiment to the front surface 11a of the semiconductor wafer 11 and grinding the back surface 11b of the wafer 11 will be described with reference to FIG. The wafer 11 having the support sheet 23C attached on the chuck table 36 is sucked and held with the support sheet 23C down, and the chuck table 36 is positioned at the grinding position shown in FIG.

  A mounter 20 is fixed to the tip of the spindle 18 of the grinding apparatus, and a grinding wheel 22 having a plurality of grinding wheels 24 at a free end is attached to the mounter 20. With respect to the wafer 11 positioned at the grinding position shown in FIG. 6A, while rotating the chuck table 36 in the direction of arrow a at, for example, 300 rpm, the grinding wheel 22 is rotated in the same direction as the chuck table 36, that is, in the direction of arrow b. For example, the grinding wheel 24 is rotated at 6000 rpm and the cutting unit feeding mechanism is operated to bring the grinding wheel 24 into contact with the back surface 11 b of the wafer 11.

  Then, the grinding wheel 22 is ground and fed by a predetermined amount at a predetermined grinding feed speed (for example, 3 to 5 μm / second), and the wafer 11 is ground. While measuring the thickness of the wafer 11 with a contact-type thickness measurement gauge (not shown), the wafer 11 is finished to a desired thickness, for example, 30 μm. When the grinding process is performed, a ground trace 31 having a pattern in which a large number of arcs are radially drawn as shown in FIG. 6B remains on the back surface (surface to be ground) 11b of the wafer 11.

  Since the support sheet 23C affixed to the surface of the semiconductor wafer 11 has the annular reinforcing member 6 embedded in the disc-shaped sheet substrate 2, the semiconductor wafer 11 is ground and thinned to about 30 μm, Further, even if the suction of the chuck table 36 is released and the semiconductor wafer 11 is removed from the chuck table 36, the thinned semiconductor wafer 11 can be supported flat because of the rigidity of the annular reinforcing member 6. Accordingly, the semiconductor wafer 11 can be easily handled and the breakage thereof can be prevented.

  As shown in FIG. 7, in order to divide the semiconductor wafer 11 whose back surface is ground and thinned into individual devices 15 with a cutting device, a conventional dicing tape T, which is an adhesive tape, is used. It was in the form of being supported by the annular frame F. This is for facilitating full cutting of the semiconductor wafer 11 and enhancing its handling properties.

  When the support sheets 23 to 23C of the present invention are used as a substitute for the dicing tape T, the annular reinforcing member is attached to the support sheet, so that it is not necessary to separately attach the annular frame F to the support sheets 23 to 23C.

  Therefore, the tension of the dicing tape T is increased by lowering the frame F, which has been a problem in supporting the wafer 11 by the conventional dicing tape T and the annular frame F, and the wafer generated by releasing the tension by cutting. 11 back surface cracks can be prevented.

2 Disc-shaped sheet base material 4 Adhesive layers 6, 8, 10 Annular reinforcing member 11 Semiconductor wafers 23 to 23C Support sheet

Claims (3)

A workpiece support sheet that is bonded to one surface of a workpiece and supports the workpiece,
A sheet substrate;
An adhesive layer formed on the sheet substrate and adhered to the workpiece;
An annular reinforcing member integrated with the sheet base material on the outer peripheral side of the sheet base material;
A support sheet for a workpiece, comprising:   The workpiece support sheet according to claim 1, wherein an outer size of the annular reinforcing member is equal to an outer size of the workpiece. The sheet substrate is selected from the group consisting of polyolefin, polyvinyl chloride and polyethylene terephthalate,
The glue layer is composed of a glue layer whose adhesive strength is reduced by an external stimulus,
The workpiece support sheet according to claim 1, wherein the annular reinforcing member is selected from the group consisting of a wire, plastic, and carbon.

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