JP2013243310A - Surface protective tape and method for processing wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective tape that allows an annular adhesive layer to be stuck only on a peripheral surplus region surrounding device regions of a wafer.SOLUTION: Surface protective tape 10 is provided for a wafer 11 that has device regions, and a peripheral surplus region surrounding the device regions, formed on a surface thereof. The surface protective tape 10 has: a substrate sheet 12 that is formed of an approximately transparent material; and an annular adhesive layer 14 that corresponds to the peripheral surplus region of the wafer 11. The annular adhesive layer 14 has: an annular sheet material 16; a first adhesive layer 18 that is disposed on a first surface of the sheet material 16; and a second adhesive layer 20 that is disposed on a second surface of the sheet material 16. By ultraviolet exposure, the first adhesive layer 18 shows a decrease in adhesive force, and the second adhesive layer 20 shows no change in adhesive force. The surface protective tape 10 is irradiated on a side of the substrate sheet 12 with ultraviolet rays, and then the substrate sheet 12 of the surface protective tape 10 is separated from the annular adhesive layer 14. Thus, only the annular adhesive layer 14 stuck on the peripheral surplus region is allowed to remain on the wafer 11.

Description

  The present invention relates to a surface protection tape for attaching an annular adhesive layer only to an outer peripheral surplus region surrounding a device region of a wafer, and a wafer processing method using the surface protection tape.

  In a semiconductor device manufacturing process, a grid-like divided division line called street is formed on the surface of a wafer made of silicon or a compound semiconductor, and devices such as ICs and LSIs are formed in each region partitioned by the division division line. . After these wafers are ground and thinned to a predetermined thickness, individual semiconductor devices are manufactured by being divided along a street by a cutting device or the like.

  For grinding the back surface of the wafer, for example, a grinding apparatus as disclosed in Japanese Patent Application Laid-Open No. 2002-200545 is used. Grinding is performed by holding the front surface side of the wafer via a surface protection tape with a chuck table of a grinding apparatus, sliding the grinding wheel while contacting the back surface of the wafer, and feeding the grinding wheel by grinding.

  In recent years, as a technology for realizing lighter, thinner, and smaller semiconductor devices, flip chips have been formed by forming a plurality of metal protrusions called bumps on the device surface, and directly bonding these bumps against the electrodes formed on the wiring board. A mounting technique called bonding has been put into practical use (see, for example, JP-A-2001-237278).

  When grinding the backside of a wafer with such bumps formed on the circuit surface, the pressure difference due to bump bumps directly affects the backside, and the cushioning of the surface protection tape that protects the surface of the wafer cannot be fully controlled. In some cases, the wafer is damaged, or the reliability of the completed device is deteriorated.

  In such a case, if it is necessary to make the finish thickness relatively thick so as not to damage the wafer or to grind it thinly, a surface protection tape with a thick adhesive layer that accommodates the bump is used. Measures were taken such as embedding bumps in the adhesive layer and grinding.

  However, when a surface protective tape having an adhesive layer that embeds bumps is used, there is a problem that if the surface protective tape is peeled off from the wafer, the adhesive layer remains as a residue on the bump or device surface.

  Therefore, the adhesive layer is attached only to the outer peripheral area surrounding the device area, and the bumps arranged relatively densely are used as support members instead of the adhesive layer, and the wafer is fixed to the chuck table and ground. Have been proposed (Patent Nos. 4462997 and 4447280).

JP 2002-200545 A JP 2001-237278 A Japanese Patent No. 4462997 Japanese Patent No. 4447280

  However, a wafer on which a device having bumps is formed may undergo various processing steps after being thinned by grinding and before being divided into device chips. For example, it is conceivable that the bumps are molded with some resin. At this time, a bank means for restricting the protrusion of the mold resin is required.

  The present invention has been made in view of the above points, and the object of the present invention is to provide a surface protection tape capable of attaching an annular adhesive layer only to an outer peripheral surplus area surrounding a device area of a wafer, and the surface protection tape. It is to provide a wafer processing method using a tape.

  According to the first aspect of the present invention, there is provided a surface protection tape that is adhered to the surface of a wafer having a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region on the surface, A base sheet formed of a substantially transparent material having an equivalent diameter, and an annular adhesive layer disposed on a peripheral portion on one side of the base sheet and corresponding to the outer peripheral surplus area of the wafer, The annular adhesive layer includes an annular sheet material corresponding to the outer peripheral surplus region, a first adhesive layer disposed on one surface of the sheet material and bonding the sheet material and the base sheet, A second pressure-sensitive adhesive layer disposed on the other surface of the sheet material and bonding the sheet material and the wafer, and the first pressure-sensitive adhesive layer is reduced in adhesive strength by irradiation of ultraviolet rays, The adhesive layer 2 has no change in adhesive strength due to UV irradiation. The surface protective tape attached to the wafer is irradiated with ultraviolet rays from the base sheet side to peel the base sheet of the surface protective tape from the annular adhesive layer, and the outer peripheral surplus area on the wafer There is provided a surface protection tape characterized in that only the annular pressure-sensitive adhesive layer adhered to the surface can remain.

  According to a second aspect of the present invention, there is provided a wafer processing method having a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region, the surface protection tape according to the first aspect. A sticking step for sticking to the surface of the wafer, and after performing the sticking step, a grinding step for holding the wafer with a chuck table via the surface protective tape and grinding the exposed back surface of the wafer; After performing the ultraviolet irradiation step of irradiating the surface protective tape with ultraviolet rays from the base sheet side, and the ultraviolet irradiation step, the base sheet of the surface protective tape is peeled off from the annular pressure-sensitive adhesive layer. A peeling step for leaving the annular adhesive layer in the outer peripheral surplus region, and the annular adhesive layer remaining in the outer peripheral surplus region and the surface of the device region of the wafer The resin is filled into a circular recess to be solidified and solidified to form a resin mold wafer, and after the resin encapsulation step, the mold resin is cut to a uniform thickness by cutting the surface of the mold resin with a cutting tool. And a dividing step of dividing the resin mold wafer into individual device chips after the cutting step is performed.

  Preferably, each device formed in the device region has a plurality of bumps. In the resin sealing step, the resin is filled in the circular recess until the bumps are buried, and in the cutting step, the mold resin is filled. Are cut together with the bumps so that the heights of the bumps are made uniform.

  According to the surface protective tape of the present invention, the annular adhesive layer can be easily attached only to the outer peripheral surplus region of the wafer. Further, according to the method for processing a wafer using the surface protection tape of the present invention, after attaching the surface protection tape to the surface of the wafer, the substrate sheet is peeled off by irradiation of ultraviolet rays, so that the outer peripheral area of the wafer The effect is that the annular adhesive layer that remains and is adhered can be used as bank means in the resin sealing step.

It is a surface side perspective view of a semiconductor wafer which has a device with a bump. It is a perspective view of the state where the surface protection tape concerning the embodiment of the present invention was stuck on the surface of the semiconductor wafer. FIG. 3A is a longitudinal sectional view showing a state in which a surface protective tape is stuck on the surface of the semiconductor wafer, and FIG. It is a partial cross section side view which shows a grinding step. It is a partial cross section side view which shows an ultraviolet irradiation step. It is a partial cross section side view which shows a peeling step. It is a partial cross section side view which shows the resin enclosure step. It is a partial cross section side view which shows a cutting step. It is a partial cross section side view which shows a division | segmentation step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a perspective view of a semiconductor wafer 11 suitable for applying the surface protection tape of the present invention. A semiconductor wafer (hereinafter sometimes abbreviated as a wafer) 11 has a front surface 11a and a back surface 11b, and a plurality of planned division lines 13 are formed orthogonally on the front surface 11a. A bumped device 15 having bumps 21 is formed in each region partitioned by 13.

  The semiconductor wafer 11 has a device region 17 where the bumped device 15 is formed and an outer peripheral surplus region 19 surrounding the device 17 on its surface. 19 a is the inner diameter of the outer peripheral surplus region 19.

  It should be noted here that the wafer to which the method of attaching the surface protection tape of the present invention is applied is not only the wafer on which the device with bumps is formed, but also on the wafer on which the device having no bumps is formed. It is applicable to.

  Referring to FIG. 2, a perspective view of the surface 11 a of the wafer 11 with the surface protection tape 10 according to the embodiment of the present invention attached thereto is shown. FIG. 3A is a longitudinal sectional view thereof. The surface protection tape 10 includes a base sheet 12 formed of a resin such as polyethylene vinyl chloride or polyolefin, and an annular adhesive layer 14 attached to the outer peripheral portion of one side of the base sheet 12.

  As shown in FIG. 3B, which is an enlarged view of portion A in FIG. 3A, the annular adhesive layer 14 includes an annular sheet material 16 corresponding to the outer peripheral surplus region 19 of the wafer 11, and an annular sheet material. A first pressure-sensitive adhesive layer 18 disposed on one surface of the sheet 16 to adhere the sheet material 16 and the base sheet 12, and a surface protection tape 10 disposed on the other surface of the sheet material 16 of the wafer 11. When adhered to the surface 11a, the surface protection tape 12 is composed of a second adhesive layer 20 that adheres to the outer peripheral surplus area 19 of the wafer 11.

  Here, the first pressure-sensitive adhesive layer 18 is formed from a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with ultraviolet rays, and the second pressure-sensitive adhesive layer 20 is formed from a pressure-sensitive adhesive that does not change in pressure-sensitive adhesive strength due to irradiation with ultraviolet rays. Yes. The base sheet 12 is made of a substantially transparent material, at least a material transparent to ultraviolet rays, and is formed in a disk shape having a diameter equivalent to the diameter of the wafer 11.

  As shown in FIG. 2 and FIG. 3A, when the surface protective tape 10 is attached to the surface 11a of the wafer 11, the annular adhesive layer 14 disposed on the outer peripheral portion of the surface protective tape 10 has an excess outer periphery of the wafer 11. The bumps 21 attached to the region 19 and formed on the surface of the wafer 11 abut against the base sheet 12 and act as a support member.

  After the surface protection tape 10 is attached to the front surface 11a of the wafer 11, a grinding step for grinding the back surface 11b of the wafer 11 is performed. In this grinding step, as shown in FIG. 4, the surface of the surface protection tape 10 attached to the wafer 11 is sucked and held by the chuck table 22 of the grinding device, and the back surface 11b of the wafer 11 is exposed.

  The grinding unit 24 of the grinding apparatus includes a spindle 26 that is rotationally driven by a motor, and a grinding wheel 28 that has a plurality of grinding wheels 30 on the outer periphery of the lower end portion that is detachably fixed to the tip of the spindle 26.

  In the grinding step, while rotating the chuck table 22 in the direction of arrow a at 300 rpm, for example, the grinding wheel 28 is rotated in the same direction as the chuck table 22, that is, in the direction of arrow b at 6000 rpm, for example. Driven to bring the grinding wheel 30 into contact with the back surface 11 b of the wafer 11.

  Then, the grinding wheel 28 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 finished thickness, for example, 50 μm.

  When the grinding is completed, as shown in FIG. 5, the back surface 11 b side of the wafer 11 is held by the chuck table 34 of the ultraviolet irradiation device, and ultraviolet rays are irradiated from the ultraviolet lamp 32 toward the surface protection tape 10.

  Since the base material sheet 12 of the surface protection tape 10 is formed of a material transparent to at least ultraviolet light, the adhesive force of the first adhesive layer 18 is reduced by the ultraviolet light that has passed through the base material sheet 12. Here, the adhesive force of the second adhesive layer 20 is maintained without being reduced.

  Thus, since the adhesive force of the 1st adhesion layer 18 is reduced by irradiation of an ultraviolet-ray, the base material sheet 12 can be easily peeled from the surface 11a of the wafer 11, as shown in FIG. The annular adhesive layer 14 remains adhered to the portion corresponding to the outer peripheral surplus region 19 of the wafer 11.

  After completion of the peeling step, as shown in FIG. 7, the resin 38 is supplied from the resin supply device 36 to the circular recess defined by the annular adhesive layer 14 remaining in the outer peripheral surplus area 19 of the wafer 11 and the device area 17 of the wafer 11. A resin encapsulation step is performed in which a resin mold wafer is formed by supplying and filling and solidifying the filled resin.

  In the resin encapsulating step of this embodiment, the annular adhesive layer 14 is used as a bank means when filling the resin into the circular recess defined by the annular adhesive layer 14 and the device region 17 of the wafer 11.

  The amount of the resin to be sealed may be within the height of the annular adhesive layer 14 with the bump 21 completely embedded. As a method of using the annular adhesive layer 14 other than the mold bank means, it can also be used as an annular support means for placing another wafer on the surface (bump surface) side of the wafer 11.

  After performing the resin sealing step, a cutting step is performed in which the surface of the resin 38 molded in the device region 17 of the wafer 11 is cut with a cutting tool to thin the mold resin 38.

  In this cutting step, as shown in FIG. 8, the back surface 11b side of the wafer 11 is sucked and held by the chuck table 40 of the cutting tool. Then, the bite tool 48 of the bite wheel 46 attached to the tip of the spindle 44 of the bite cutting unit 42 is cut into the annular adhesive layer 14 by a predetermined depth, and the chuck table 40 is moved to the arrow B while the bite wheel 46 is rotated in the arrow A direction. The mold resin 38 held in the chuck table 40 is turned by linear movement in the direction.

  When this turning cutting is completed, the bumps 21 are cut together with the mold resin 38 so that the bumps 21 are exposed from the mold resin 38 and are evenly aligned.

  After the cutting step by the cutting tool is completed, a dividing step for dividing the wafer 11 with the bumps 21 having the same height into individual device chips 23 is performed. This dividing step is performed by a dicing apparatus or a laser processing apparatus.

  FIG. 9 shows an outline of the dividing step by the dicing apparatus. In this division step, after performing an alignment step for aligning the division line 13 of the wafer 11 held on the chuck table 50 of the dicing apparatus with the cutting blade 54, the cutting blade 54 of the cutting unit 52 is moved at a high speed (for example, 30000 rpm). Cutting is performed from the surface 11a of the wafer 11 to the dicing tape T while being rotated, and the chuck table 50 is processed and fed in a direction perpendicular to the paper surface, thereby forming divided grooves.

  While indexing and feeding the cutting blade 54, similar split grooves are formed along all the planned split lines 13 extending in the first direction. Next, after the chuck table 50 is rotated by 90 degrees, a similar dividing groove is formed along the planned dividing line 13 extending in the second direction orthogonal to the first direction, so that the wafer 11 becomes the device chip 23. It is divided into.

DESCRIPTION OF SYMBOLS 10 Surface protection tape 11 Semiconductor wafer 12 Base sheet 14 Annular adhesion layer 15 Device 17 with a bump 17 Device area | region 18 1st adhesion layer 19 Peripheral surplus area 20 2nd adhesion layer 21 Bump 32 UV lamp 38 Resin 48 Byte tool 52 Cutting blade

Claims (3)

A surface protection tape that is attached to the surface of a wafer having a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region on the surface,
A base sheet formed of a substantially transparent material having a diameter equivalent to that of a wafer, and an annular adhesive layer disposed on a peripheral portion of one side of the base sheet and corresponding to the outer peripheral surplus area of the wafer. ,
The annular adhesive layer includes an annular sheet material corresponding to the outer peripheral surplus region, a first adhesive layer that is disposed on one surface of the sheet material and bonds the sheet material and the base sheet, A second adhesive layer disposed on the other surface of the sheet material and adhering the sheet material and the wafer,
The first adhesive layer has an adhesive strength that is reduced by irradiation with ultraviolet rays,
The second adhesive layer has no change in adhesive force due to ultraviolet irradiation,
The surface protective tape attached to the wafer is irradiated with ultraviolet rays from the base sheet side to peel the base sheet of the surface protective tape from the annular adhesive layer, and the outer peripheral area is formed on the wafer. A surface protective tape, wherein only the adhered annular adhesive layer can remain. A wafer processing method having a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region on a surface,
An adhering step of adhering the surface protection tape according to claim 1 to the surface of the wafer;
A grinding step of holding the wafer with a chuck table via the surface protection tape and grinding the exposed back surface of the wafer after performing the attaching step;
An ultraviolet irradiation step of irradiating the surface protection tape with ultraviolet rays from the substrate sheet side;
After performing the ultraviolet irradiation step, a peeling step of peeling the base sheet of the surface protection tape from the annular adhesive layer to leave the annular adhesive layer in the outer peripheral area of the wafer;
Filling a resin into a circular recess defined by the annular adhesive layer remaining in the outer peripheral surplus region and the surface of the device region of the wafer and solidifying the resin to form a resin mold wafer;
After performing the resin sealing step, the cutting step of cutting the surface of the mold resin with a cutting tool to form the mold resin in a uniform thickness;
After performing the cutting step, a dividing step of dividing the resin mold wafer into individual device chips;
A wafer processing method characterized by comprising: Each device formed in the device region has a plurality of bumps,
In the resin sealing step, the circular recess is filled with resin until the bumps are buried,
3. The wafer processing method according to claim 2, wherein in the cutting step, the height of the bumps is made uniform by cutting the mold resin together with the bumps.

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