JP2012015231A - Tape sticking method - Google Patents

Abstract

To provide a tape attaching method capable of improving the peelability of an ultraviolet curing protective tape.
A tape adhering method for adhering an ultraviolet curing protective tape 3 to a wafer 1 having a plurality of protruding electrodes 2 formed on the surface, the step of supplying nitrogen to a surface 1a of the wafer 1, and the wafer And a step of adhering an ultraviolet curing protective tape 3 to the surface 1a of the wafer 1 in a state where nitrogen is supplied to the surface 1a.
[Selection] Figure 2

Description

  The present invention relates to a tape attaching method for attaching an ultraviolet curing protective tape to a wafer.

  In the semiconductor device manufacturing process, division lines are formed in a lattice pattern on the wafer surface, and devices such as IC and LSI are formed in each of a plurality of areas partitioned by the division lines. After the device is formed on the front surface in this way, the back surface of the wafer is ground by a grinding device, and the wafer is adjusted to a predetermined thickness. Thereafter, the wafer is cut along a planned dividing line by a cutting apparatus and divided into individual devices.

  A protective tape for protecting a device formed on the surface is attached to the front surface of the wafer carried into the grinding apparatus during back surface grinding, and this protective tape is peeled off from the wafer after the grinding process. The protective tape is an ultraviolet curable protective tape having an ultraviolet curable adhesive, and is irradiated with ultraviolet rays before the peeling step. Then, the ultraviolet curable pressure-sensitive adhesive is cured by the ultraviolet irradiation, and the ultraviolet curable protective tape having reduced adhesive strength is peeled off from the surface of the wafer.

  The UV curable adhesive contained in the UV curable protective tape may not be fully UV cured due to oxygen inhibition, so a curing process is proposed in which UV irradiation is performed under a nitrogen atmosphere to completely cure the UV curable adhesive. (For example, refer to Patent Document 1).

JP 2008-251934 A

  By the way, when protruding electrodes called bumps are formed on the wafer surface, if a UV curable protective tape is attached to the wafer surface, a gap is formed at the interface without the wafer and the UV curable protective tape being in close contact with each other. Sometimes. In this case, even when the ultraviolet curing protective tape is irradiated with ultraviolet rays in a nitrogen atmosphere, the nitrogen gas does not sufficiently penetrate into the gap. Therefore, oxygen (air) present in the gaps inhibits UV curing, and the UV curable pressure-sensitive adhesive is not sufficiently UV cured, and the peelability of the UV curable protective tape may deteriorate.

  This invention is made | formed in view of this point, and it aims at providing the tape sticking method which can improve the peelability of a ultraviolet curing protective tape.

  The tape adhering method of the present invention is a tape adhering method for adhering an ultraviolet curing protective tape to a wafer having a plurality of protruding electrodes formed on the surface, and supplying nitrogen to the surface of the wafer; Adhering the ultraviolet curing protective tape to the surface of the wafer in a state where nitrogen is supplied to the surface of the wafer.

  According to this tape sticking method, even when the electrode is formed so as to protrude from the surface of the wafer, the gap formed at the interface between the wafer and the ultraviolet curing protective tape can be filled with nitrogen. Therefore, when the ultraviolet curing protective tape is cured by ultraviolet irradiation, oxygen inhibition can be suppressed and the entire ultraviolet curing protective tape can be appropriately cured. As a result, it becomes possible to improve the peelability of the ultraviolet curable protective tape.

  ADVANTAGE OF THE INVENTION According to this invention, the tape sticking method which can improve the peelability of a ultraviolet curing protective tape can be provided.

It is the cross-sectional schematic diagram (a) which shows the wafer which concerns on embodiment of this invention, and the cross-sectional schematic diagram (b) which shows the state by which the ultraviolet curing protection tape was affixed on the wafer. It is explanatory drawing which shows the processing process of a wafer in order of (a)-(f). It is a cross-sectional schematic diagram (a)-(d) which expands and shows the clearance gap formed in the interface of the surface of a wafer, and an ultraviolet curable adhesive layer.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In all the drawings, components having the same function are described using the same reference numerals.

(About wafer 1)
FIG. 1A is a schematic cross-sectional view showing a wafer 1 according to the present embodiment. On the surface 1 a of the wafer 1, division lines are formed in a lattice shape, and devices (not shown) such as IC and LSI are formed in each of a plurality of areas partitioned by the division lines. A plurality of protruding electrodes 2 are formed on the surface 1a of the wafer 1 as terminals for connecting these devices to a substrate or the like.

  The plurality of electrodes 2 are formed in a substantially spherical shape from the surface 1a of the wafer 1, and are arranged at a predetermined interval. In the protruding direction, the electrode 2 has a width that increases from the base end side to the middle portion, and narrows from the middle portion toward the distal end side. Thus, the electrode 2 forms a constricted portion with the surface 1a of the wafer 1 on the base end side.

  FIG. 1B is a schematic cross-sectional view showing a state in which the ultraviolet curing protective tape 3 is attached to the surface 1 a of the wafer 1. The ultraviolet curable protective tape 3 includes a tape substrate 31 and an ultraviolet curable adhesive layer 32 formed by applying an ultraviolet curable paste to one surface of the tape substrate 31. The tape substrate 31 preferably has a thickness of about 100 μm, and the ultraviolet curable adhesive layer 32 preferably has a thickness that can completely cover the electrode 2. The electrode 2 has a height of 50 μm to 200 μm.

Here, the wafer 1 is not particularly limited, but, for example, a semiconductor wafer such as silicon (Si), gallium gallium (GaAs), or silicon carbide (SiC), a sapphire (Al ₂ O ₃ ) -based inorganic material substrate, or the like. Is mentioned.

  A gap 5 is formed around the electrode 2 between the surface 1 a of the wafer 1 and the ultraviolet curable adhesive layer 32. The gap 5 is formed by the electrode 2 partially hindering the adhesion between the ultraviolet curable adhesive layer 32 and the wafer 1. The size of the gap 5 depends on the elastic modulus and film thickness of the ultraviolet curable adhesive layer 32. However, since the base end side of the electrode 2 is constricted on both sides, it is difficult for the ultraviolet curable adhesive layer 32 to enter the constricted portion.

Subsequently, the processing steps of the wafer 1 will be described with reference to FIG.
(1. Step of supplying nitrogen to the surface 1a of the wafer 1)
FIG. 2A is a schematic cross-sectional view showing a state where nitrogen is supplied to the surface 1 a of the wafer 1. On the chuck table 4, an ultraviolet curing protective tape 3 is installed so as to face the surface 1 a of the wafer 1. Further, nitrogen is supplied to the surface 1 a of the wafer 1. In this step, for example, nitrogen gas is continuously supplied in the direction indicated by the arrow A to remove the air around the wafer 1 and the ultraviolet curable protective tape 3 and to surround the wafer 1 and the ultraviolet curable protective tape 3. Filled with nitrogen. Note that the state in which nitrogen is supplied refers to a state in which nitrogen gas is continuously supplied or a state in a nitrogen atmosphere.

(2. About the process of sticking the ultraviolet curing protective tape 3 on the surface 1a of the wafer 1)
FIG. 2B is a schematic cross-sectional view showing a state where the ultraviolet curing protective tape 3 is attached to the surface 1 a of the wafer 1. In this step, the wafer 1 is pressed against the ultraviolet curable adhesive layer 32 of the ultraviolet curable protective tape 3 from above with nitrogen supplied. At this time, the ultraviolet curable adhesive layer 32 is attached to the wafer 1 so as to cover the surface 1 a of the wafer 1 and the electrode 2. Further, at the interface between the wafer 1 and the ultraviolet curable adhesive layer 32, the plurality of electrodes 2 partially inhibits sticking, and a gap 5 is generated.

  Since the ultraviolet curing protective tape 3 is attached to the surface 1a of the wafer 1 in a state where nitrogen is supplied to the surface 1a of the wafer 1, the gap 5 is filled with nitrogen. Note that the gap 5 only needs to contain nitrogen in such a ratio that the gap 5 has an oxygen concentration that does not inhibit ultraviolet curing.

(3. Grinding process)
FIG. 2C is a schematic cross-sectional view showing the state of the wafer 1 adjusted to a predetermined thickness by the grinding process. In FIG. 2C, the broken line indicates the thickness of the wafer 1 before the grinding process.

  In this process, the wafer 1 carried into the grinding apparatus is sucked and held by the chuck table 4 with the ultraviolet curing protective tape 3 facing downward, and the back surface 1b of the wafer 1 is set facing the grinding wheel. The chuck table 4 and the grinding wheel are rotated relative to each other, and the grinding wheel is ground and fed downward until the wafer 1 has a predetermined thickness.

  In addition, the process and the grinding | polishing process of sticking the ultraviolet curing protective tape 3 on the surface 1a of the wafer 1 may be performed on the chuck table 4 of the same apparatus, or may be performed on the chuck table 4 of another apparatus.

(4. Curing process)
FIG. 2D is a schematic cross-sectional view showing a state in which the ultraviolet curing protective tape 3 is irradiated with ultraviolet rays. Before irradiating the ultraviolet curing protective tape 3 with ultraviolet rays, nitrogen is supplied around the ultraviolet curing protective tape 3. In this step, for example, nitrogen gas is continuously supplied in the direction indicated by the arrow A to remove the air around the ultraviolet curing protective tape 3 and to fill the nitrogen around the ultraviolet curing protective tape 3. .

  Thereafter, ultraviolet rays are irradiated from the ultraviolet irradiation unit 6 to the ultraviolet curing protective tape 3 from the direction indicated by the arrow B in a nitrogen atmosphere. The ultraviolet curable pressure-sensitive adhesive layer 32 contains a photopolymerization initiator, and the ultraviolet curable pressure-sensitive adhesive layer 32 is cured by a photopolymerization reaction caused by radicals generated from the photopolymerization initiator by ultraviolet irradiation. In addition, since the oxygen concentration around the ultraviolet curable protective tape 3 is reduced, the ultraviolet curable pressure-sensitive adhesive layer 32 can be ultraviolet cured without being affected by the inhibition of ultraviolet curing by oxygen.

  At this time, since the gap 5 is also filled with nitrogen, the ultraviolet curable pressure-sensitive adhesive layer 32 around the gap 5 can be ultraviolet-cured without being affected by ultraviolet-curing inhibition by oxygen.

  In addition, if the circumference | surroundings and the clearance gap 5 of the ultraviolet curing protective tape 3 become the oxygen concentration which does not inhibit ultraviolet curing, gases inert to ultraviolet curing reaction other than nitrogen gas, for example, helium, argon, carbon dioxide Or you may perform the process and the hardening process of sticking the ultraviolet curing protective tape 3 in the atmosphere of these mixed gas.

(5. About sticking process of dicing tape 7)
FIG. 2E is a schematic cross-sectional view showing a state where the dicing tape 7 is attached to the back surface 1 b of the wafer 1. In this process, the ultraviolet curing protective tape 3 side of the wafer 1 is directed upward. The dicing tape 7 has an outer peripheral portion attached to the annular frame 8 so as to cover the opening of the annular frame 8, and the wafer 1 is supported by the annular frame 8 via the dicing tape 7.

  In addition, although the case where the process of sticking the back surface 1b of the wafer 1 to the dicing tape 7 is performed after the curing process has been described above, the order of the two processes may be reversed. That is, after the process of sticking the back surface 1b of the wafer 1 to the dicing tape 7, a curing process may be performed.

(6. About the peeling process)
FIG. 2F is a schematic cross-sectional view showing a state where the cured ultraviolet curing protective tape 3 is peeled and the surface 1a and the electrode 2 of the wafer 1 are exposed. As a method of peeling off the ultraviolet curing protective tape 3 after curing, for example, a method of peeling the ultraviolet curing protective tape 3 by gripping the outer periphery of the ultraviolet curing protective tape 3 attached to the wafer 1 or any arbitrary one of the wafer 1 Examples thereof include a method of peeling the ultraviolet curing protective tape 3 by bringing a roller into contact from one end to the other end.

  Since the entire ultraviolet curable adhesive layer 32 is appropriately cured, the ultraviolet curable protective tape 3 has a reduced adhesive force and an improved peelability. Therefore, when the ultraviolet curable protective tape 3 is peeled off, damage to the wafer 1 and the devices and electrodes 2 formed on the surface 1a of the wafer 1 due to the adhesive force of the ultraviolet curable adhesive layer 32 can be prevented.

  Next, a characteristic part of the present invention will be described in detail with reference to FIG. Here, the case where the gap 5 is filled with nitrogen and the case where the gap 5 is filled with oxygen will be described in comparison.

  First, the case where the gap 5 is filled with nitrogen will be described. FIG. 3A is a schematic cross-sectional view showing the gap 5 filled with nitrogen in an enlarged manner. Even if the ultraviolet curing irradiation of the ultraviolet curing protective tape 3 is performed in a nitrogen atmosphere, the nitrogen gas does not sufficiently penetrate into the gap 5. However, since the gap 5 is filled with nitrogen, it does not contain oxygen at a concentration that inhibits ultraviolet curing. Therefore, in the ultraviolet curable adhesive layer 32 around the gap 5, oxygen inhibition of the ultraviolet curable reaction does not occur, and the entire ultraviolet curable adhesive layer 32 is appropriately cured.

  FIG. 3B is a schematic cross-sectional view showing a peeling process of the ultraviolet curable pressure-sensitive adhesive layer 32 that has been properly cured as a whole. In this case, the ultraviolet curable adhesive layer 32 can be peeled from the surface 1 a of the wafer 1 without the ultraviolet curable adhesive layer 32 adhering to the surface 1 a of the wafer 1 or the electrode 2 in the peeling step.

  Next, a case where the gap 5 is filled with oxygen instead of nitrogen will be described. FIG.3 (c) is a cross-sectional schematic diagram which expands and shows the clearance gap 5 filled with oxygen. Even if the ultraviolet curing irradiation of the ultraviolet curing protective tape 3 is performed in a nitrogen atmosphere, the nitrogen gas does not sufficiently penetrate into the gap 5. Therefore, the gap 5 contains oxygen at a concentration that inhibits ultraviolet curing. Therefore, in the ultraviolet curable adhesive layer 32 around the gap 5, oxygen inhibition of the ultraviolet curable reaction occurs, and the uncured portion 32a of the ultraviolet curable adhesive layer 32 remains.

  FIG. 3D is a schematic cross-sectional view illustrating a state in which the ultraviolet curable adhesive layer 32 in which the uncured portion 32a remains is peeled off. The uncured portion 32a of the ultraviolet curable adhesive layer 32 adheres to the surface 1a of the wafer 1 and the electrode 2 in the peeling process, and causes the wafer 1 to be contaminated. Alternatively, the ultraviolet curing protective tape 3 cannot be peeled off from the surface 1a of the wafer 1, causing the wafer 1 to be damaged.

  Here, since the ultraviolet curable adhesive layer 32 around the gap 5 is not originally in contact with the surface 1a or the electrode 2 of the wafer 1, it is considered that problems such as contamination of the wafer 1 do not occur. However, as shown in FIG. 3D, the uncured portion 32 a of the ultraviolet curable adhesive layer 32 may come into contact with the surface 1 a of the wafer 1 or the electrode 2 during the peeling. In this case, problems such as contamination of the wafer 1 occur.

  Therefore, when the uncured portion 32a of the UV curable adhesive layer 32 remains, the peelability of the UV curable protective tape 3 after UV curing is higher than when the entire UV curable adhesive layer 32 is properly cured. Can be said to be worse.

  As described above, according to the tape adhering method according to the embodiment, even when the electrode protrudes from the surface of the wafer, the gap formed at the interface between the wafer and the UV curable protective tape. Can be filled with nitrogen. Therefore, when the ultraviolet curing protective tape is cured by ultraviolet irradiation, oxygen inhibition can be suppressed and the entire ultraviolet curing protective tape can be appropriately cured. As a result, it becomes possible to improve the peelability of the ultraviolet curable protective tape.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above embodiment, the case where the substantially spherical electrode 2 is formed on the surface 1a of the wafer 1 is described. However, it is not limited to the said structure, The electrode 2 can apply arbitrary shapes.

  Moreover, the tape sticking method according to the above embodiment can be applied not only when the electrode 2 is formed on the surface 1 a of the wafer 1. For example, when an uneven shape is formed on the surface 1a of the wafer 1 due to a device or a cutting groove formed on the surface 1a of the wafer 1, or when the ultraviolet curing protective tape 3 is in close contact with the surface 1a of the wafer 1. This is useful in all cases where the gap 5 can be formed at the interface between the wafer 1 and the UV curable protective tape 3, such as when it cannot be attached.

  As described above, the present invention has the effect of improving the peelability of the ultraviolet curing protective tape, and in particular, the ultraviolet curing protection is applied to a wafer on which protruding electrodes called bumps are formed on the surface. Useful when sticking tapes.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Electrode 3 UV-curing protection tape 31 Tape base material 32 UV-curing adhesive layer 32a Uncured part of UV-curing adhesive layer 4 Chuck table 5 Gap 6 Ultraviolet irradiation part 7 Dicing tape 8 Ring frame

Claims (1)

A tape adhering method for adhering an ultraviolet curing protective tape to a wafer having a plurality of protruding electrodes formed on the surface,
Supplying nitrogen to the surface of the wafer;
A step of adhering the ultraviolet curing protective tape to the surface of the wafer in a state where nitrogen is supplied to the surface of the wafer.

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