Fabrication method of semiconductor device

A fabrication method of a semiconductor device according to the present invention includes the steps of: bonding a reinforcing plate with a front surface of a semiconductor wafer via a reinforcing plate, the reinforcing plate having holes and the semiconductor wafer bearing semiconductor devices; grinding a back surface of the semiconductor wafer; and detaching the reinforcing plate from the semiconductor wafer by injecting a solvent for dissolving an adhesive layer into the holes and by allowing the solvent to permeate through the adhesive layer. The method enables the reinforcing plate to be quickly detached from the semiconductor wafer without causing defects, such as bending and cracking, in the semiconductor wafer after the reinforcing plate is used to grind the semiconductor wafer.

This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on patent application Ser. No. 2003/089348 filed in Japan on Mar. 27, 2003, the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to fabrication methods of semiconductor devices, in which, for example, a thin layer of semiconductor wafer is prepared and diced to obtain individual semiconductor devices.

BACKGROUND OF THE INVENTION

With a current demand for three-dimensional stacking or high-density packaging of semiconductor devices, it is important nowadays to provide thin semiconductor wafers. One method to provide a thin semiconductor wafer is to lap (grind) the back surface of a semiconductor wafer with a grind stone. While the method is pervasive for it offers good productivity, a drawback of the method is that it may produce micro cracks in the back surface of the semiconductor wafer when the semiconductor wafer is ground, with the result that the bending strength of the semiconductor wafer may be reduced. In order to prevent chipping or cracking that may develop in the semiconductor wafer by an applied external force of grinding, the method requires the semiconductor wafer to be supported (anchored) on a reinforcing member when grinding the back surface of the semiconductor wafer.

The mechanical strength of the semiconductor wafer is weak, and the method requires a “stress-free” technique in which the semiconductor wafer is removed (detached) from the reinforcing member without exerting stress. This is particularly important when a thin semiconductor wafer is provided, in which case the mechanical strength of the semiconductor wafer is even weaker.

In order to grind the semiconductor wafer by anchoring it on a reinforcing member, it is required (1) to anchor the semiconductor wafer on the reinforcing member with such an adhesion force that can withstand back grinding, and (2) to detach the semiconductor wafer from the reinforcing member without exerting stress on the semiconductor wafer that was ground to a reduced thickness.

Conventionally, there have been proposed anchoring and detaching methods for semiconductor wafer and reinforcing member. For example, Japanese Publication for Unexamined Patent Application Nos. 12492/2000 (Tokukai 2000-12492, published on Jan. 14, 2000), and 44144/2001 (Tokukai 2001-44144, published on Feb. 16, 2001) disclose methods in which a UV curable adhesive is used for the bonding, and a reinforcing member is detached by reducing the adhesion force by irradiation of UV light. In another method, a thermoplastic adhesive is used for the bonding, and the reinforcing member is detached by softening the adhesive by applied high-temperature heat after grinding, as disclosed in Japanese Publication for Unexamined Patent Application Nos. 217213/2001 (Tokukai 2001-217213, published on Aug. 10, 2001), 203821/2002 (Tokukai 2002-203821, published on Jul. 19, 2002), and 80938/1994 (Tokukaihei 6-80938, published on Mar. 22, 1994), for example.

In all of these methods, the back surface of the semiconductor wafer is ground while maintaining a strong adhesion force between the semiconductor wafer and reinforcing member. After back grinding, the adhesion force is reduced by irradiation of UV light or application of high-temperature heat, so as to mechanically detach the reinforcing member from the semiconductor wafer while an adhesive layer is still attached on the reinforcing member.

Referring toFIG. 5, the following describes a conventional fabrication method of a thin semiconductor device using a UV curable adhesive.

First, a reinforcing plate31is attached via a UV adhesive layer32, on a front surface35of a semiconductor wafer33bearing semiconductor devices (not shown) (FIG. 5(a)). Then, while reinforcing the semiconductor wafer33with the reinforcing plate31, a back surface (portion33b) of the semiconductor wafer33is ground to provide a semiconductor wafer33aof a reduced thickness (FIG. 5(b)). Thereafter, a dicing tape36is attached on the back surface (ground surface41) of the semiconductor wafer33a(FIG. 5(c)). The dicing tape36serves as a support when dividing the semiconductor wafer33ainto individual semiconductor devices.

Next, by irradiation of UV light46on the UV adhesive layer32, the adhesion force of the UV adhesive layer32is reduced (FIG. 5(d)). In the next step, a mechanical force is applied on the reinforcing plate31to detach the reinforcing plate31and the adhesive layer32from the semiconductor wafer33a(FIG. 5(e)). Finally, the semiconductor wafer33ais diced into individual pieces of semiconductor device30(FIG. 5(f)), and the divided pieces of semiconductor device30are picked up (FIG. 5(g)).

Note that, the method using a thermoplastic adhesive follows the same steps, except that the method uses a thermoplastic adhesive instead of a UV curable adhesive (adhesive layer32), and that high-temperature heat is applied instead of UV light.

While the method using a UV curable adhesive can reduce the adhesion force of the adhesive to a certain point by irradiation of UV light, it cannot completely remove the adhesive sticking to the front surface of the semiconductor wafer33a. That is, a remaining adhesive retains its adhesion force on the front surface of the semiconductor wafer33a. In this case, when a mechanical force is applied on the reinforcing member31to detach the reinforcing member31from the semiconductor wafer33a, the adhesive remaining on the front surface of the semiconductor wafer33atransmits the mechanical force to the semiconductor wafer33a, pulling the semiconductor wafer33a.

In the step of detaching the reinforcing plate31from the semiconductor wafer33a, the reinforcing plate31is attached on the back surface of the semiconductor wafer33a(seeFIG. 5(e)). The dicing tape36is not rigid, and the adhesion between the dicing tape36and the semiconductor wafer33ais not strong enough to retain the state (planar shape) of the semiconductor wafer33aagainst the mechanical force that transmits to the semiconductor wafer33a(force pulling the semiconductor wafer33a). This may cause cracking in the semiconductor wafer33awhen detaching the reinforcing plate31from the semiconductor wafer33a. As one can imagine, the problem of cracking becomes even more serious when the thickness or size of the semiconductor wafer33ais increased.

Another drawback of the conventional methods is that the reinforcing plate31requires a material that transmits UV light46. That is, the material of the reinforcing plate31is limited to UV transmissive materials.

The methods using a thermoplastic adhesive may also cause the problem of cracking in the semiconductor wafer33awhen the reinforcing plate31is detached from the semiconductor wafer33a.

Further, owning to the fact that the semiconductor wafer33aand the reinforcing plate31have different coefficients of thermal expansion, the semiconductor wafer33amay be fractured when high-temperature heat (for example, above 100° C.) is applied to reduce the adhesion force of the adhesive.

In order to prevent these problems, Japanese Publication for Unexamined Patent Application No. 222491/1996 (Tokukaihei 8-222491, published on Aug. 30, 1996) discloses a method in which an adhesive layer is dissolved to detach the reinforcing plate.

The method (may be referred to as “conventional method” hereinafter) dissolves the adhesive layer in the manner shown inFIG. 6(a) andFIG. 6(b). First, the semiconductor wafer33aand adhesive layer32are immersed in a solvent45that can dissolve the adhesive (FIG. 6(a)). The solvent45dissolves the adhesive layer32, and the reinforcing plate31is detached (FIG. 6(b)). In this method, the reinforcing plate31is detached from the semiconductor wafer33aafter the adhesive layer32is removed. Accordingly, no mechanical force is exerted on the semiconductor wafer33awhen the reinforcing plate31is detached.

In the conventional method, however, the reinforcing plate31is detached while the adhesive layer32and the semiconductor wafer33aare immersed in the solvent45. That is, the reinforcing plate31needs to be detached without a support, such as a dicing tape, on a back surface41of the semiconductor wafer33a(seeFIG. 6(a)). More specifically, the semiconductor wafer33a, with the reinforcing plate31detached and with its thickness reduced, is not supported on a support. This makes it extremely difficult to handle the semiconductor wafer33awithout causing cracking or chipping.

As a countermeasure, a support, such as a dicing tape, may be attached on the semiconductor wafer33aafter the reinforcing plate31is detached. However, in this case, the semiconductor wafer33amay be cracked or bent when the dicing tape is pressed against the back surface of the semiconductor wafer33a.

An alternative method is shown inFIG. 7(a) andFIG. 7(b).

As illustrated inFIG. 7(a), after grinding the semiconductor wafer33, a dicing tape36is attached on a back surface41of the semiconductor wafer33awith a reinforcing plate31attached on a front surface35of the semiconductor wafer33a. Then, with a support jig37covering the dicing tape36and the side surface of the semiconductor wafer33a, a solvent45is allowed to gradually permeate through an adhesive layer32from the sides to inside the adhesive layer32, without touching the dicing tape36. The solvent45dissolves the adhesive layer32, and the reinforcing plate31is detached, as shown inFIG. 7(b). In this manner, the method enables the reinforcing plate31to be detached from the semiconductor wafer33a, with the dicing tape36attached on the semiconductor wafer33a.

The method requires the solvent45to gradually permeate through the adhesive layer32from the sides to inside the adhesive layer32. This is problematic in that it takes time to completely dissolve the adhesive layer32and thereby enables the reinforcing plate31to be detached from the semiconductor wafer33a.

Another drawback is that the adhesive layer32is not dissolved uniformly when the adhesive layer32is gradually dissolved from the periphery. This produces uneven stress over the semiconductor wafer33asupported by the reinforcing plate31and the support jig37, causing the semiconductor wafer33ato bend or crack.

SUMMARY OF THE INVENTION

The present invention was made in view of the foregoing problems, and it is an object of the present invention to provide a fabrication method of a semiconductor device, whereby a reinforcing material is quickly detached from a semiconductor wafer without bending or cracking the semiconductor wafer, when the reinforcing material is used to grind the semiconductor wafer.

In order to achieve this object, a method for fabricating a semiconductor device according to the present invention includes: a reinforcing step of bonding a reinforcing plate, via an adhesive layer, on a front surface of a semiconductor wafer bearing one or more semiconductor devices; a grinding step of grinding a back surface of the semiconductor wafer; and a detaching step of detaching the reinforcing plate from the semiconductor wafer, wherein the reinforcing plate has an injection path that connects a surface in contact with the adhesive layer with a surface other than the surface in contact with the adhesive layer, and wherein, in the detaching step, a solvent for dissolving the adhesive layer is injected through the injection path of the reinforcing plate, so as to permeate the adhesive layer and detach the reinforcing plate from the semiconductor wafer.

The injection path (hole or groove) of the reinforcing plate connects the interface of the reinforcing plate and the adhesive layer (the interface being a back surface of the reinforcing plate) with a front surface or side surface of the reinforcing plate. The front surface of the semiconductor wafer bears one or more semiconductor devices, and the back surface of the semiconductor wafer is subjected to grinding. The front surface of the semiconductor wafer is bonded with the reinforcing plate via the adhesive layer. The reinforcing plate enables the back surface of the semiconductor wafer to be ground while reinforcing the semiconductor wafer. In this way, a thin semiconductor wafer can be realized without causing cracking or bending.

In the detaching step, a solvent for dissolving the adhesive layer is injected through the injection path, so that the solvent directly permeates the interface of the reinforcing plate and the adhesive layer. This enables the adhesive layer to be dissolved in a short period of time, thereby quickly eliminating the adhesion force acting between the reinforcing plate and the semiconductor wafer. Thus, with the method for the present invention, the reinforcing plate can be detached from the semiconductor wafer more quickly than with a conventional method in which the adhesive layer is dissolved from the sides.

Further, because no mechanical stress is exerted on the semiconductor wafer when it is detached, the semiconductor wafer can be detached from the reinforcing plate without causing cracking, chipping, or bending.

Further, because the method prevents the solvent from touching the dicing tape, the method is also advantageous in, for example, attaching a dicing tape on the back surface of the semiconductor wafer when the dicing tape is used to support the semiconductor wafer when it is separated. Thus, with a fabrication method of the present invention, the detaching step can be carried out without removing the dicing tape.

DESCRIPTION OF THE EMBODIMENTS

Referring toFIGS. 1(a) through1(g), andFIG. 2, a First Embodiment of the present invention is described below.

The present embodiment provides the following five fabrication steps (Step1(S1) through Step5(S5)). In Step1, a reinforcing plate1and a semiconductor wafer3(3a,3b) are bonded with each other with an adhesive layer2interposed in between (reinforcing step,FIG. 1(a)). In Step2, the semiconductor wafer3bis ground (grinding step,FIG. 1(b)). In Step3, a dicing tape6is attached on a back surface11of the semiconductor wafer3a(bonding step,FIG. 1(c)). In step4, a solvent15is injected through holes4of the reinforcing plate1, so as tot separate the semiconductor wafer3afrom the reinforcing plate1(detaching step,FIGS. 1(d) and1(e)). In step5, the semiconductor wafer3ais diced after it is separated from the reinforcing plate1, and individual pieces of semiconductor device16are picked up (dicing step,FIGS. 1(g) and1(f)).

FIG. 2illustrates a state in the reinforcing step (S1), in which the reinforcing plate1and the semiconductor wafer3aare bonded with each other via the adhesive layer2. As shown inFIG. 2, the reinforcing plate1has a plurality of holes4through which the solvent is injected to dissolve the adhesive layer2. The holes4are scattered over the entire surface of the reinforcing plate1, penetrating through the reinforcing plate1from a front surface10to a back surface9. Preferably, the holes4are evenly scattered (at regular intervals).

This is preferable for the advantage it offers in the detaching step (S4, seeFIGS. 1(d) and1(e)). Namely, when the holes4are regularly (evenly) spaced over the entire surface of the reinforcing plate1, the solvent15can pass through the holes4to directly and evenly permeate the interface of the reinforcing plate1and the adhesive layer2. This enables the adhesive layer2to be dissolved in a short period of time, thereby quickly eliminating the adhesion force acting between the reinforcing plate1and the semiconductor wafer3a. That is, the reinforcing plate1can be quickly detached from the semiconductor wafer3a.

Referring toFIGS. 1(a) through1(g), the respective fabrication steps are described below in more detail.

First, as illustrated inFIG. 1(a), the reinforcing plate1and the semiconductor wafer3(3a,3b) are bonded with each other, with the adhesive layer2interposed in between (reinforcing step (S1)). A multiplicity of semiconductor devices (not shown) makes up a front surface5of the semiconductor wafer3. The reinforcing plate1has evenly (regularly) spaced holes4that connect the front surface10and back surface9of the reinforcing plate1. The type of adhesive used for the adhesive layer2is such that it provides strong adhesion that can withstand the mechanical stress of grinding when a back surface11of the semiconductor wafer3ais ground in the grinding step (S2).

Next, in order to reduce the thickness of the semiconductor wafer3(3a,3b), the back surface11of the semiconductor wafer3is ground to remove the portion3bof the semiconductor wafer3(grinding step (S2)), as shown inFIG. 1(b). Here, the mechanical stress of grinding (vibration, etc.) is absorbed by the reinforcing plate1tightly attached on the semiconductor wafer3a, thereby preventing the semiconductor wafer3afrom being cracked or bent. The semiconductor wafer3aso formed has a thickness of about 50 to 100 μm.

In the next step, the dicing tape6is bonded on the back surface11of the semiconductor wafer3a(bonding step (S3)), as shown inFIG. 1(c). The dicing tape6is required when dicing the semiconductor wafer3ainto individual pieces of semiconductor device (not shown).

Next, as shown inFIG. 1(d), a support jig7is fastened on the side surface of the semiconductor wafer3a. Here, the support jig7also surrounds other members used in the fabrication method. The support jig7is a ring and is in contact with the sides of the reinforcing plate1, the adhesive layer2, and the semiconductor wafer3a. The support jig7serves to support these members, and to prevent the solvent15that has dissolved the adhesive layer2from leaking outside (particularly to the dicing tape6).

The solvent15is for dissolving the adhesive layer2. When the solvent15is injected through the holes4, it uniformly (evenly) permeates the interface of the reinforcing plate1and the adhesive layer2, and thereby quickly dissolves the adhesive layer2. As a result, the semiconductor wafer3ais quickly detached from the reinforcing plate1(detaching step (S4)), as shown inFIG. 1(e). Here, the semiconductor wafer3amay be allowed to detach itself from the reinforcing plate1by the force of gravity, or by removing the support jig7from the semiconductor wafer3a.

In the dicing step (S5), the semiconductor wafer3adetached from the reinforcing plate1is diced (divided into individual semiconductor chips) as shown inFIG. 1(f), using the dicing tape6as a support, and the divided pieces of semiconductor device16are picked up as shown inFIG. 1(g). For dicing, any conventional dicing technique may be used.

The semiconductor device16so fabricated by the foregoing fabrication method has a thickness of about 50 to 150 μm, which is thin enough to meet the requirements of thin semiconductor devices.

Referring toFIG. 3(a) throughFIG. 3(g), andFIG. 4, a Second Embodiment of the present invention is described below.FIG. 3(a) throughFIG. 3(g) illustrate fabrication steps of the present embodiment.

First, as illustrated inFIG. 3(a), a reinforcing plate21and a semiconductor wafer3(3a,3b) are bonded with each other, with an adhesive layer2interposed in between (reinforcing step (S1)). A multiplicity of semiconductor devices (not shown) makes up a front surface5of the semiconductor wafer3. The reinforcing plate21has a back surface9(facing the semiconductor wafer3via the adhesive layer2) with narrow grooves8, as illustrated inFIG. 4.

As shown inFIG. 4, the narrow grooves8are provided in the form of a lattice throughout the back surface9of the reinforcing plate21. Each narrow groove8extends to the side surface of the reinforcing plate21, and has ends8a(on the side surface of the reinforcing plate1) that constitute an opening (narrow groove opening) for the solvent. The solvent is injected through the opening of the narrow groove8to dissolve the adhesive layer2in the subsequent detaching process. The type of adhesive used for the adhesive layer2is such that it provides strong adhesion that can withstand the mechanical stress of grinding when the back surface11of the semiconductor wafer3ais ground in the grinding step (S2).

Next, in order to reduce the thickness of the semiconductor wafer3(3a,3b), the back surface11is ground to remove the portion3bof the semiconductor wafer3. (grinding step (S2)), as shown inFIG. 3(b). Here, the mechanical stress of grinding (vibration, etc.) is absorbed by the reinforcing plate21tightly attached on the semiconductor wafer3a, thereby preventing the semiconductor wafer3afrom being cracked or bent. The semiconductor wafer3aso formed has a thickness of about 50 to 150 μm.

In the next step, a dicing tape6is bonded on the back surface11of the semiconductor wafer3a(bonding step (S3)), as shown inFIG. 3(c). The dicing tape6is required when dicing the semiconductor wafer3ainto individual pieces of semiconductor device (not shown).

Next, as shown inFIG. 3(d), a support jig17is fastened on the side surface of the semiconductor wafer3a. Here, the support jig17also surrounds other members used in the fabrication method. The support jig17is a ring and is in contact with the sides of the reinforcing plate21, the adhesive layer2, and the semiconductor wafer3a. The support jig17serves to support these members, and to prevent the solvent15that has dissolved the adhesive layer2from leaking outside (particularly to the dicing tape6). Further, as illustrated inFIG. 3(d), the support jig17has an injection opening18, so that the solvent15does not touch the dicing tape6when it is injected.

The solvent15is for dissolving the adhesive that forms the adhesive layer2, and it is injected through the injection opening18. The solvent15injected through the injection opening18flows into the narrow grooves8of the lattice through the narrow groove opening8a, and uniformly (evenly) permeates the interface of the reinforcing plate21and the adhesive layer2, thereby quickly dissolving the adhesive layer2. As a result, the semiconductor wafer3ais quickly detached from the reinforcing plate21(detaching step (S4)), as shown inFIG. 3(e). Here, the semiconductor wafer3amay be allowed to detach itself from the reinforcing plate21either by the force of gravity, or by removing the support jig17from the semiconductor wafer3a.

In the dicing step (S5), the semiconductor wafer3adetached from the reinforcing plate21is diced (divided into individual semiconductor chips) as shown inFIG. 3(f), using the dicing tape6as a support, and the divided pieces of semiconductor device16are picked up as shown inFIG. 3(g). For dicing, any conventional dicing technique may be used.

The semiconductor device16so fabricated by the foregoing fabrication method has a thickness of about 50 to 150 μm, which is thin enough to meet the requirements of thin semiconductor devices.

The narrow grooves8on the back surface9of the reinforcing plate21are provided in the form of a lattice in the present embodiment. However, the narrow grooves8are not just limited to the lattice pattern. For example, the narrow grooves8may be provided to radiate outward from the center toward the side of the reinforcing plate21.

In the foregoing First and Second Embodiments, the injection path for the solvent15is realized by the holes4through the reinforcing plate (seeFIG. 2for example) or the narrow grooves8on the reinforcing plate (seeFIG. 4for example). However, the injection path is not just limited thereto, and it may be realized in any form provided that the injection path provides a passageway from the outer face (front surface, side surface) to the back surface (the surface in contact with the adhesive layer2) of the reinforcing plate, and that the solvent15is injected to the adhesive layer2. For example, the injection path may be a channel that connects a side surface of the reinforcing plate to the back surface by bending inside the reinforcing plate. Alternatively, the injection path may be realized by a combination of the hole and the narrow groove, with the end of the hole opening into the narrow groove on the back surface of the reinforcing plate.

As described, in preferred embodiments of the present invention, the solvent15for dissolving the adhesive layer2is injected through the injection path of the reinforcing plate (for example, holes4inFIG. 2, and narrow grooves8inFIG. 4). This enables the solvent15to directly and evenly permeate the adhesive layer2, thus quickly dissolving the adhesive layer2. As a result, the detaching step (S4) can be carried out in a considerably short period of time. This is particularly advantageous for a large-sized semiconductor wafer3awith a proportionally increased area for the adhesive layer2. In this case, by evenly providing the holes4or narrow grooves8over the increased area, the solvent15is able to quickly permeate the entire area of the adhesive layer2to dissolve the adhesive layer2.

Further, because no mechanical stress is exerted on the semiconductor wafer3awhen detaching the reinforcing plate from the semiconductor wafer3a, the semiconductor wafer3ais protected from defects such as cracking or bending.

Further, the foregoing fabrication method does not use ultraviolet light or heat to detach the reinforcing plate. This affords more freedom in terms of a selection of material for the reinforcing plate. The method is also advantageous when the adhesive layer2is made of a material that cannot withstand heat.

Further, because the adhesive in the adhesive layer2is dissolved uniformly, the problem of cracking or bending can be prevented that occurs when the adhesive layer2is unevenly dissolved and when uneven stress is applied on the semiconductor wafer3a.

Further, the solvent15permeates the adhesive layer2through the holes4or narrow grooves8, and the solvent15is unlikely to touch the dicing tape6attached on the back surface11of the semiconductor wafer3a. This enables the dicing tape6to be made of a material with poor solvent resistance.

It should be appreciated that the present invention is not just limited to the foregoing embodiments, and the invention may be varied in many ways within the scope of the claims. Further, the technical means described in the foregoing embodiments may be suitably combined to constitute a new embodiment, and all such combinations of the technical means are intended to fall within the scope of the present invention.

As described, a method for fabricating a semiconductor device according to the present invention includes: a reinforcing step of bonding a reinforcing plate, via an adhesive layer, on a front surface of a semiconductor wafer bearing one or more semiconductor devices, the reinforcing layer having one or more holes that connect a front surface and a back surface of the reinforcing layer; a grinding step of grinding a back surface of the semiconductor wafer; and a detaching step of detaching the reinforcing plate from the semiconductor wafer by injecting Through the holes a solvent for dissolving the adhesive layer.

The front surface of the semiconductor wafer bears one or more semiconductor devices, and the back surface of the semiconductor wafer is subjected to grinding. The front surface of the semiconductor wafer is bonded with the reinforcing plate via the adhesive layer. The reinforcing plate reinforces the semiconductor wafer when the back surface of the semiconductor wafer is ground. In this way, a thin semiconductor wafer can be achieved without causing cracking or bending.

In the detaching step, a solvent for dissolving the adhesive layer is injected through the holes, so that the solvent directly permeates the interface of the reinforcing plate and the adhesive layer. This enables the adhesive layer to be dissolved in a short period of time, thereby quickly eliminating the adhesion force acting between the reinforcing plate and the semiconductor wafer. Thus, with the method of the present invention, the reinforcing plate can be detached from the semiconductor wafer more quickly than with a conventional method in which the adhesive layer is dissolved from the sides.

Further, because no mechanical stress is exerted on the semiconductor wafer when it is detached, the semiconductor wafer can be detached from the reinforcing plate without causing cracking, chipping, or bending.

As described, a method for fabricating a semiconductor device according to the present invention includes: a reinforcing step of bonding a reinforcing plate, via an adhesive layer, with a semiconductor wafer bearing a semiconductor device on its front surface, the reinforcing plate having a surface with one or more grooves that extend to a side surface of the reinforcing plate, wherein the reinforcing plate is bonded with the semiconductor wafer so that the surface with the grooves is in contact with the front surface of the semiconductor wafer; a grinding step of grinding a back surface of the semiconductor wafer; and a detaching step of detaching the reinforcing plate from the front surface of the semiconductor wafer by injecting into the grooves a solvent for dissolving the adhesive layer.

The reinforcing plate has a surface with one or more grooves that extend to a side surface of the reinforcing plate. The front surface of the semiconductor wafer bears one or more semiconductor devices, and the back surface of the semiconductor wafer is subjected to grinding. The semiconductor wafer is bonded with the reinforcing plate via the adhesive layer, with the front surface of the semiconductor wafer facing the surface of the reinforcing plate with one or more grooves. The reinforcing plate reinforces the semiconductor wafer when the back surface of the semiconductor wafer is ground. In this way, a thin semiconductor wafer can be achieved without causing cracking or bending.

In the detaching step, a solvent for dissolving the adhesive layer is injected into an end of the groove (an opening on a side surface of the reinforcing plate), so that the solvent directly permeates the interface of the reinforcing plate and the adhesive layer. This enables the adhesive layer to be dissolved in a short period of time, thereby quickly eliminating the adhesion force acting between the reinforcing plate and the semiconductor wafer. Thus, with the method of the present invention, the reinforcing plate can be detached from the semiconductor wafer more quickly than with a conventional method in which the adhesive layer is dissolved from the sides.

Further, because no mechanical stress is exerted on the semiconductor wafer when it is detached, the semiconductor wafer can be detached from the reinforcing plate without causing cracking, chipping, or bending.

In the method for fabricating a semiconductor device according to the present invention, the holes are scattered over the reinforcing plate.

With the holes scattered over the reinforcing plate, the solvent injected through the holes can more quickly dissolve the adhesive layer. This is particularly advantageous for a large-sized semiconductor wafer with a proportionally increased area for the adhesive layer. In this case, by scattering the holes over the increased area, the solvent can more quickly permeate and dissolve the entire area of the adhesive layer.

Further, with the scattered holes, the adhesive layer can be dissolved uniformly. By thus dissolving the adhesive layer without creating an uneven distribution in the adhesive layer, the problem of cracking or bending can be prevented that occurs when the adhesive layer is unevenly dissolved.

In the method for fabricating a semiconductor device according to the present invention, the grooves are scattered (in the form of a lattice, for example) over a surface of the adhesive layer.

With the grooves scattered over a surface of the reinforcing plate, the solvent injected through the grooves can more quickly dissolve the adhesive layer. This is particularly advantageous for a large-sized semiconductor wafer with a proportionally increased area for the adhesive layer. In this case, by scattering the grooves over the increased area, the solvent can more quickly permeate and dissolve the entire area of the adhesive layer.

Further, with the scattered grooves, the adhesive layer can be dissolved substantially uniformly. Because the adhesive layer is uniformly dissolved without creating an uneven distribution in the adhesive layer, the problem of cracking or bending can be prevented that occurs when the adhesive layer is unevenly dissolved.

As described, a method for fabricating a semiconductor device according to the present invention includes: a reinforcing step of bonding a reinforcing plate, via an adhesive layer, on a front surface of a semiconductor wafer bearing one or more semiconductor devices, the reinforcing layer having one or more holes that connect a front surface and a back surface of the reinforcing layer; a grinding step of grinding a back surface of the semiconductor wafer; a bonding step of bonding a dicing tape on the back surface of the semiconductor wafer after grinding; a detaching step of detaching the reinforcing plate from the semiconductor wafer by injecting through the holes a solvent for dissolving the adhesive layer; and a dicing step of dicing the semiconductor wafer so as to separate the semiconductor devices into individual pieces.

The dicing tape is used in the dicing step to support the semiconductor wafer.

In the detaching step, a solvent for dissolving the adhesive layer is injected through the holes, so that the solvent directly permeates the interface of the reinforcing plate and the adhesive layer. This enables the adhesive layer to be dissolved in a short period of time, thereby quickly eliminating the adhesion force acting between the reinforcing plate and the semiconductor wafer. Thus, with the method for the present invention, the reinforcing plate can be detached from the semiconductor wafer more quickly than with a conventional method in which the adhesive layer is dissolved from the sides.

Further, because no mechanical stress is exerted on the semiconductor wafer when it is detached, the semiconductor wafer can be detached from the reinforcing plate without causing cracking, chipping, or bending.

Further, the solvent permeates the adhesive layer through the holes, and the solvent is unlikely to touch the dicing tape attached on the back surface of the semiconductor wafer. This enables the dicing tape to be made of a material with poor solvent resistance.

As described, a method for fabricating a semiconductor device according to the present invention includes: a reinforcing step of bonding a reinforcing plate, via an adhesive layer, with a semiconductor wafer bearing one or more semiconductor devices on its front surface, the reinforcing plate having a surface with one or more grooves that extend to a side surface of the reinforcing plate, wherein the reinforcing plate is bonded with the semiconductor wafer so that the surface with the grooves is in contact with the front surface of the semiconductor wafer; a grinding step of grinding a back surface of the semiconductor wafer; a bonding step of bonding a dicing tape on the back surface of the semiconductor wafer after grinding; a detaching step of detaching the reinforcing plate from the front surface of the semiconductor wafer by injecting into the grooves a solvent for dissolving the adhesive layer; and a dicing step of dicing the semiconductor devices so as to separate the semiconductor devices into individual pieces.

In the detaching step, a solvent for dissolving the adhesive layer is injected through the grooves, so that the solvent directly permeates the interface of the reinforcing plate and the adhesive layer. This enables the adhesive layer to be dissolved in a short period of time, thereby quickly eliminating the adhesion force acting between the reinforcing plate and the semiconductor wafer. Thus, with the method of the present invention, the reinforcing plate can be detached from the semiconductor wafer more quickly than with a conventional method in which the adhesive layer is dissolved from the sides.

Further, because no mechanical stress is exerted on the semiconductor wafer when it is detached, the semiconductor wafer can b& detached from the reinforcing plate without causing cracking, chipping, or bending.

Further, the solvent permeates the adhesive layer through the grooves, and the solvent is unlikely to touch the dicing tape attached on the back surface of the semiconductor wafer. This enables the dicing tape to be made of a material with poor solvent resistance.

In the method for fabricating a semiconductor device according to the present invention, a side surface of the adhesive layer is covered with a jig, before the solvent is injected to the holes in the detaching step.

In the detaching step, a jig covers a side surface of the adhesive layer, so that the solvent that has dissolved the adhesive layer does not leak outside (to the back surface of the semiconductor wafer, for example). Thus, it is even more unlikely that the solvent touches the dicing tape attached to the back surface of the semiconductor wafer.

In the method for fabricating a semiconductor device according to the present invention, a side surface of the adhesive layer is covered with a jig, before the solvent is injected to the grooves in the detaching step. The solvent is injected into the grooves through an injection opening provided through the jig.

In the detaching step, a jig is used to cover a side surface of the adhesive layer, so that the solvent that has dissolved the adhesive layer does not leak outside (to the back surface of the semiconductor wafer, for example). Thus, it is even more unlikely that the solvent touches the dicing tape attached to the back surface of the semiconductor wafer.