JP7173091B2 - Surface grinding method - Google Patents

Description

The present invention relates to a surface grinding method.

A coating is formed by coating resin or wax on one side of the wafer, curing the resin on a flat surface plate, and grinding the wafer based on this coating to remove waviness and warpage of the wafer. There is a surface grinding method (Patent Document 1, etc.).

An example of a conventional surface grinding method will be described with reference to FIG.
First, as shown in FIG. 13A, a wafer 1 having a first principal surface 11 and a second principal surface 12 opposite to the first principal surface 11 is prepared. Wafer 1 includes an edge portion 13 located between first major surface 11 and second major surface 12 . Such a wafer 1 is obtained, for example, by slicing a semiconductor single crystal (for example, silicon single crystal) ingot, which is the raw material of the wafer 1, into a workpiece and chamfering the sliced workpiece. In addition, in FIG. 13, for the sake of explanation, the first main surface 11 and the second main surface 12 are shown as having large unevenness, but the surfaces of the first main surface 11 and the second main surface 12 Roughness is not particularly limited.

Next, a resin such as an adhesive material is applied to the second main surface 12 and the edge portion 13 of the wafer 1, and the resin or the like is cured on the flat base member 4 (base plate or film) to form a coating. As a result, as shown in FIG. 13C, the resin layer 3 covering the second main surface 12 and the edge portion 13 of the wafer 1 is obtained, and the wafer 1 is fixed to the base member 4 . As a result, the workpiece 5, which is the object to be processed, is obtained.

Subsequently, the workpiece 5 is supported and fixed to a supporting and fixing means (for example, a vacuum chuck) using the lower surface of the base member 4 as a reference surface, and the first main surface 11 of the wafer 1 is ground. As a result, the wafer 1a having the ground first main surface 11a shown in FIG. 13(d) is obtained.

Next, as shown in FIG. 13(e), the base member 4 is removed from the workpiece 5. Next, as shown in FIG. Subsequently, as shown in FIG. 13(f), the workpiece 5 is turned over, and the wafer 1a is supported and fixed by vacuum chuck means or the like at the position of the ground first main surface 11a, and the second main surface of the wafer 1a is 12 is surface-ground. As a result, a wafer 1b having a ground first main surface 11a and a ground second main surface 12a is obtained as shown in FIG. 13(g).

As shown in FIG. 13(g), the surface grinding of the second main surface 12 removes the portion of the resin layer 3 covering the second main surface 12, but the portion 33 of the resin layer 3 is removed. remains on the edge portion 13 of the wafer 1b.

Finally, cleaning is performed to remove stains on the ground first principal surface 11a and the ground second principal surface 12a of the wafer 1b (FIG. 13(h)).

JP 2009-148866 A JP 2019-165152 A JP 2016-219634 A

Summarizing the conventional method described above with reference to FIG. is removed, the workpiece 5 is reversed, and the second main surface 12 is ground. Thereby, both sides of the wafer 1 are ground.

Here, as shown in FIG. 13C, the resin layer 3 is formed so as to cover not only the second main surface 12 of the wafer 1 but also the edge portion 13 which is the chamfered portion of the wafer 1 . As shown in FIG. 13(e), the base member 4 is peeled off before the second main surface 12 is ground. Therefore, it is difficult to separate the base member 4 from the wafer 1 and the resin layer 3, and there is a problem that the wafer 1 is broken.

Further, as shown in FIG. 13(h), there is a problem that a portion 33 of the resin layer 3 remaining on the edge portion 13 of the wafer 1b cannot be completely removed even if cleaning is performed after double-sided grinding. A remaining portion 33 of the resin layer 3 cannot be removed by etching or the like in a post-process, resulting in a problem of failure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wafer surface grinding method capable of grinding both sides of a wafer while preventing cracks in the wafer and residual resin at the edge of the wafer. With the goal.

In order to solve the above problems, the present invention provides a wafer surface grinding method comprising:
An edge portion having a first principal surface and a second principal surface opposite to the first principal surface and located between the first principal surface and the second principal surface by the slicing step and the chamfering step providing a wafer comprising
applying a release agent to a portion of the second main surface and the edge of the wafer to form a release agent layer;
forming a resin layer covering the second main surface and the entire edge portion on the release agent layer;
disposing a base member on the resin layer to obtain a wafer composite;
Grinding the first major surface of the wafer while supporting and fixing the wafer composite at the position of the base member;
removing the base member from the wafer composite;
Grinding the second main surface of the wafer while supporting and fixing the wafer at the position of the ground first main surface;
washing the wafer to remove the release agent layer and the resin layer remaining on the edge portion of the wafer.

With such a surface grinding method, both sides of the wafer can be ground while preventing the wafer from cracking and resin from remaining at the edge.

It is preferable that the edge portion is in a range of 2 mm or less from the edge of the outermost periphery of the wafer, and the release agent is applied to the edge portion.
As a result, it is possible to reliably prevent the resin from remaining at the edge portion.

It is more preferable to apply the mold release agent to the edge portion with the edge portion being in the range of 0.3 mm from the outermost edge of the wafer.
As a result, it is possible to more reliably prevent the resin from remaining on the edge portion.

Preferably, the release agent is applied so as to cover 30% or more and less than 100% of the second main surface of the wafer.
As a result, it is possible to sufficiently suppress the adhesion between the wafer and the resin layer while sufficiently suppressing the peeling of the resin layer from the wafer during grinding, thereby preventing the wafer from cracking when the base member is removed. can be suppressed more reliably.

The release agent layer can be formed on the second main surface of the wafer in a lattice, linear, radial, dotted, concentric, spiral, dashed, or checkered pattern.
Thus, the release agent layer formed on a portion of the second main surface can have various shapes.

Any one of silicone-based, long-chain alkyl-based, fluorine-based, aliphatic amide-based, and silica-based release agents can be used as the release agent.
As described above, various kinds of release agents can be used.

It is preferable that the release agent is applied only to the part and the edge of the second main surface of the wafer.
Such a method is economical because the range of use of the release agent can be minimized.

Said cleaning can be done by brush cleaning or two-fluid cleaning.
According to the present invention, even such a simple physical cleaning can sufficiently remove the resin layer remaining on the edge portion.

As described above, according to the wafer surface grinding method of the present invention, both sides of the wafer can be ground while preventing cracks in the wafer and residual resin on the edge portion of the wafer.

1 is a flow chart schematically showing a portion of a wafer surface grinding method of the present invention. 1 is a flow chart showing a part of an example of a wafer surface grinding method of the present invention. FIG. 3 is a flow chart showing part of an example of the wafer surface grinding method of the present invention continued from the flow chart of FIG. 2 ; FIG. FIG. 4 is a schematic cross-sectional view showing some aspects of edge portions in the present invention; 1 is a flow chart showing an example of a wafer processing method including a wafer surface grinding method of the present invention. 1 is a schematic flow chart of Example 1 and Comparative Example 1; 4 is a more detailed flowchart of Example 1; 5 is a more detailed flowchart of Comparative Example 1; 4 is an enlarged image of an edge portion of one wafer after double-sided grinding obtained in Example 1. FIG. 4 is an enlarged image of an edge portion of another wafer after double-sided grinding obtained in Example 1. FIG. 4 is an enlarged image of an edge portion of one wafer after double-sided grinding obtained in Comparative Example 1. FIG. 3 is an enlarged image of an edge portion of another wafer after double-sided grinding obtained in Comparative Example 1. FIG. It is a flowchart of an example of the conventional surface grinding method.

As described above, there has been a demand for the development of a wafer surface grinding method capable of grinding both sides of a wafer while preventing cracks in the wafer and residual resin on the edge of the wafer.

As a result of extensive studies on the above problems, the present inventors have found that before forming a resin layer on the wafer, a release agent is applied to a part of the second main surface and the edge of the wafer to remove the mold. By forming the agent layer, it is possible to prevent peeling of the resin layer during grinding, prevent cracking of the wafer when removing the base member, and facilitate removal of the resin from the edge portion. The present invention has been completed by discovering that it can be performed in

That is, the present invention is a method for surface grinding a wafer,
An edge portion having a first principal surface and a second principal surface opposite to the first principal surface and located between the first principal surface and the second principal surface by the slicing step and the chamfering step providing a wafer comprising
applying a release agent to a portion of the second main surface and the edge of the wafer to form a release agent layer;
forming a resin layer covering the second main surface and the entire edge portion on the release agent layer;
disposing a base member on the resin layer to obtain a wafer composite;
Grinding the first major surface of the wafer while supporting and fixing the wafer composite at the position of the base member;
removing the base member from the wafer composite;
Grinding the second main surface of the wafer while supporting and fixing the wafer at the position of the ground first main surface;
washing the wafer to remove the release agent layer and the resin layer remaining on the edge portion of the wafer.

Incidentally, Patent Document 2 discloses a semiconductor device including a semiconductor substrate and a chamfer compensation portion added to the outer periphery thereof. In this patent document 2, in a method for manufacturing a semiconductor device, a resin containing silica filler, which is a material of the chamfer compensation portion, is applied to the chamfer portion of the semiconductor substrate and the mold in order to facilitate the separation of the chamfer compensation portion from the mold. The addition of a release agent prior to filling between the frames is disclosed. However, Patent Document 2 does not disclose a specific aspect of adding a release agent.

Further, Patent Document 3 discloses a laminate in which a substrate and a support plate provided with a separation layer on the entire periphery of the surface facing the substrate are laminated via a first adhesive layer. A laminated body is disclosed. In this laminate, the first adhesive layer contains silicone oil as a mold release agent, thereby adjusting the adhesive force so that the substrate and the support plate can be preferably separated. However, Patent Document 3 does not describe or suggest forming a layer of a release agent on the substrate separately from the first adhesive layer.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

First, referring to FIG. 1, the wafer surface grinding method of the present invention will be schematically described.
First, a wafer 1 shown in FIG. 1(1) is prepared by a slicing process and a chamfering process. The wafer 1 has a first major surface 11 and a second major surface 12 opposite the first major surface 11, and an edge portion 13 located between the first major surface 11 and the second major surface 12. including. Although FIG. 1A shows the cross section of the wafer 1 and does not show the entire edge portion 13 , the edge portion 13 extends along the edge of the outermost periphery of the wafer 1 .

Next, as shown in FIG. 1(1), a part of the second main surface 12 and the edge portion 13 of the wafer 1 are coated with a release agent to form a release agent layer 2 .

Next, on the release agent layer 2, the resin layer 3 shown in FIG. Next, the base member 4 is placed on the resin layer 3 to obtain the wafer composite 10 shown in FIG. 1(2).

Next, the obtained wafer composite 10 is supported and fixed at the position of the base member 4, and the first main surface 11 of the wafer 1 is ground. The base member 4 is then removed from the wafer composite 10 . Next, the second main surface 12 of the wafer 1 is ground while the wafer 1 is supported and fixed at the position of the ground first main surface 11A. Thereby, as shown in FIG. 1(3), a wafer 1B having a ground first principal surface 11A and a ground second principal surface 12A is obtained.

Thereafter, the wafer 1B is washed to remove a portion 23 of the release agent layer 2 and a portion 33 of the resin layer 3 remaining on the edge portion 13 of the wafer 1B. As a result, as shown in FIG. 1(4), a wafer 1C from which a portion 23 of the release agent layer 2 and a portion 33 of the resin layer 3 are removed from the edge portion 13 is obtained.

In the wafer surface grinding method of the present invention, before the resin layer 3 is formed on the wafer 1, a part of the second main surface 12 and the edge portion 13 of the wafer 1 are coated with a mold release agent. By forming the layer 2, the adhesive strength of the resin layer 3 to the wafer 1 can be moderately suppressed. 1 can be prevented from splitting. Further, the resin layer 33 remaining on the edge portion 13 of the wafer 1C can be easily removed together with the release agent layer 23 by simple cleaning after double-side grinding. On the other hand, since the release agent layer 2 is applied to a part of the second main surface 12 of the wafer, the adhesive force of the resin layer 3 to the wafer 1 is peeled off when the first main surface 11 of the wafer 1 is ground. can be large enough to prevent

Next, a specific example will be shown with reference to FIGS. 2 and 3 to describe the wafer surface grinding method of the present invention in more detail.

(wafer preparation)
First, as shown in FIG. 2A, a wafer 1 having a first principal surface 11 and a second principal surface 12 opposite to the first principal surface 11 is prepared. Wafer 1 includes an edge portion 13 located between first major surface 11 and second major surface 12 . Such a wafer 1 is obtained, for example, by slicing a workpiece from an ingot of a semiconductor single crystal (for example, silicon single crystal), which is the raw material of the wafer 1, and beveling the cut workpiece. In addition, the slicing process and the chamfering process are not limited to these methods, and can be performed by various known methods.

Further, in FIG. 2, for the sake of explanation, the first main surface 11 and the second main surface 12 are shown as having large unevenness, but the surfaces of the first main surface 11 and the second main surface 12 Roughness is not particularly limited. The edge portion 13 can include not only the outermost edge of the wafer 1 obtained by the chamfering process, but also a portion adjacent to this edge. Details will be described later with reference to FIG.

(Formation of release agent)
Next, as shown in FIG. 2B, part of the second main surface 12 and the edge portion 13 of the prepared wafer 1 are coated with a release agent to form a release agent layer 2 .

The release agent is applied so as to cover the edge portion 13 as shown in FIG. 2(B). On the other hand, the release agent is applied to a part of the second main surface 12 rather than the entire surface. If the mold release agent is applied to the entire surface of the second main surface 12, the bonding strength between the resin layer formed in a later step and the wafer 1 is weak, and there is a risk that the resin layer will be peeled off during grinding, and the abrasive will enter through the peeled gaps. The shape may change.

It is preferable to apply the release agent so as to cover 30% or more and less than 100% of the second main surface 12 of the wafer 1 .

By doing so, the bonding area between the resin layer 3 to be formed in a later step and the wafer 1 can be set in a more appropriate range. As a result, it is possible to sufficiently suppress the adhesion between the wafer 1 and the resin layer 3 while sufficiently suppressing the peeling of the resin layer 3 from the wafer 1 during grinding. (arranged on the resin layer 3) can be more sufficiently suppressed from cracking the wafer 1 when removing it.

More preferably, the release agent is applied so as to cover 40% or more and less than 90% of the second main surface 12 of the wafer 1 .

The release agent layer 2 can be formed on the second main surface 12 of the wafer 1 in, for example, a lattice, linear, radial, dotted, concentric, spiral, broken line, or checkered pattern. .
Thus, the release agent layer can take various shapes.

Moreover, the release agent to be used is not particularly limited. For example, any one of silicone-based, long-chain alkyl-based, fluorine-based, aliphatic amide-based, and silica-based release agents can be used as the release agent.
As described above, various kinds of release agents can be used.

The release agent is preferably applied only to a portion of the second main surface 12 and the edge portion 13 of the wafer 1 as shown in FIG. 2(B).

The resin layer 3 to be formed in a later step is provided for supporting and fixing the first main surface 11 of the wafer 1 during grinding. Therefore, it is not necessary to form the release agent layer 2 for the resin layer 3 on the first main surface 11 , and therefore it is not necessary to apply the release agent on the first main surface 11 . By applying only a part of the second main surface 12 and the edge portion 13 without applying the release agent to the first main surface 11 of the wafer 1, the use range of the release agent can be minimized and economical. target. In addition, since the release agent layer 2 is not formed, grinding of the first main surface 11 is facilitated. However, a release agent may be applied onto the first main surface 11 .

(Formation of resin layer and placement of base member)
Next, as shown in FIG. 2C, a resin layer 3 is formed on the release agent layer 2 to cover the second main surface 12 and the edge portion 13 of the wafer 1 entirely. The resin layer 3 has a release agent contact surface 32 in contact with the release agent layer and a base contact surface 31 opposite to the release agent contact surface 32 . Further, as shown in FIG. 2C, the base member 4 is arranged on the resin layer 3 so as to be in contact with the base contact surface 31 . As a result, a wafer composite 10 including the wafer 1, the release agent layer 2, the resin layer 3, and the base member 4 is obtained.

The material of the resin layer 3 is not particularly limited, and for example, an adhesive or the like that is commonly used for fixing semiconductor wafers can be used. The resin layer 3 can adhere to the part of the second main surface 12 of the wafer 1 where the release agent layer 2 is not formed and the release agent layer 2 by curing. Curing may be performed after applying the material of the resin layer 3 and before arranging the base member 4 or after arranging the base member 4 .

The base member 4 is a member for flattening one surface of the wafer composite 10 so that it can be supported and fixed. Although the form of the base member 4 is not particularly limited, it is, for example, a base plate or a film.

(Grinding of first main surface)
Next, the wafer composite 10 shown in FIG. 2(C) is supported and fixed at the position of the base member 4 . The means for supporting and fixing is not particularly limited, and means commonly used in processing semiconductor wafers, such as a vacuum chuck, can be employed.

Next, the first main surface 11 of the wafer 1 is ground while the wafer composite 10 is supported and fixed as described above. Since the resin layer 3 is adhered to the second principal surface 12 of the wafer 1 with sufficient strength, it is possible to prevent the resin layer 3 from peeling off from the wafer 1 during the grinding of the first principal surface 11 . Thereby, a wafer 1A having a ground first main surface 11A as shown in FIG. 2(D) is obtained.

(Removal of base member)
Next, the base member 4 is removed from the wafer composite 10, as shown in FIG. 3(E). In the method of the present invention, since the release agent layer 2 is formed not on the entire surface of the second main surface 12 of the wafer 1 but on a part thereof, the adhesion of the resin layer 3 to the wafer 1A having the ground first main surface 11A is can be moderately suppressed. As a result, it is possible to prevent the wafer 1A from cracking when the base member 4 is peeled off from the wafer composite 10 after grinding the first main surface 11 . As a result, the workability of surface grinding is improved, and the productivity and yield of wafers are improved.
By removing the base member 4 from the wafer composite 10, the base contact surface 31 of the resin layer 3 is exposed.

(Reversal and support fixation)
Next, as shown in FIG. 3(F), the wafer 1A is turned over so that the base contact surface 31 of the resin layer 3 faces the grinding machine (upward direction in FIG. 3). Next, the wafer 1A oriented in this direction is supported and fixed at the position of the ground first main surface 11A. The support and fixation means are not particularly limited as before.

(Grinding of second main surface)
Next, the second main surface 12 of the wafer 1A is ground while the wafer 1A is supported and fixed as described above. Thereby, a wafer 1B having a ground first principal surface 11A and a ground second principal surface 12A as shown in FIG. 3(G) is obtained. 3(F) and 3(G), a part 20 of the release agent layer 2 formed on the second main surface 12 and A portion 30 of the resin layer 3 is also removed. On the other hand, as shown in FIG. 3G, a portion 23 of the release agent layer 2 and a portion 33 of the resin layer 3 remain on the edge portion 13 of the wafer 1B.

(Washing)
Next, the wafer 1B is cleaned. This cleaning removes a portion 23 of the release agent layer 2 and a portion 33 of the resin layer 3 remaining on the edge portion 13 .

Due to the presence of the portion 23 of the release agent layer 2 remaining on the edge portion 13 , the portion 33 of the resin layer 3 can be easily removed from the edge portion 13 . The portion 23 itself of the release agent layer 2 can be easily removed from the edge portion 13 . Therefore, cleaning for removing the release agent layer 2 and the resin layer 3 from the edge portion 13 can be performed by simple physical cleaning such as brush cleaning or two-fluid cleaning.

This cleaning can also remove dirt on the ground first principal surface 11A and the ground second principal surface 12A.

By this cleaning, a wafer 1C having a ground first principal surface 11A and a ground second principal surface 12A opposite to the first principal surface 11A, as shown in FIG. 3(H), is obtained.

According to the wafer surface grinding method of the present invention, the first main surface 11 is ground while the position of the base member 4 is fixed, and the ground second main surface 11A is fixed at the position of the second main surface 11A. Since the main surface 12 is ground, waviness and warpage of the wafer 1 can be effectively removed.

3(H), the release agent layer 2 and the resin layer 3 are sufficiently removed from the edge portion 13 of the wafer 1C.

Therefore, the wafer whose both sides have been ground by the wafer surface grinding method of the present invention can be suitably processed in the post-process such as etching.

Next, the edge portion of the wafer prepared by the wafer surface grinding method of the present invention will be described.

As previously mentioned, the edge of the wafer can include not only the outermost edge of the wafer obtained by the chamfering process, but also the portion adjacent to this edge.

For example, as shown in FIG. 4, in one aspect of the invention, the edge portion 13 of the wafer 1 is defined by the outermost edge 13E of the wafer 1, adjacent to this edge and extending no more than 2 mm from the edge. It may include portions 11E and 12E. In the method of this aspect, by forming the release agent layer 2 so as to completely cover the edge portion 13 , it is possible to more effectively prevent the resin from remaining on the edge portion 13 .

In a more preferred embodiment of the present invention, the edge portion 13 of the wafer 1 includes the outermost edge 13E of the wafer 1 and the portions 11e and 12e adjacent to this edge and within a range of 0.3 mm from the edge. In the method of this aspect, by forming the release agent layer 2 so as to completely cover the edge portion 13 , it is possible to effectively prevent the resin from remaining on the edge portion 13 .

For the sake of convenience, in this specification, the portions 11E and 11e adjacent to the edges are described as not included in the first main surface 11 of the wafer 1. As shown in FIG. Similarly, the edge-adjacent portions 12E and 12e described above are described as not included in the second major surface 12 of the wafer 1 .

<Wafer processing method>
The wafer surface grinding method of the present invention can be applied as part of a wafer processing method.

FIG. 5 shows a flowchart showing an example of a wafer processing method including the wafer surface grinding method of the present invention.

This processing method includes a slicing step S1, a chamfering step S2, a grinding step S3 and an etching step S4.

The slicing step S1 and the chamfering step S2 are means for preparing the wafer as described above. The grinding step S3 corresponds to the steps of the above-described wafer surface grinding method of the present invention, excluding the slicing step S1 and the chamfering step S2. That is, the slicing step S1, the chamfering step S2, and the grinding step S3 shown in FIG. 5 constitute the wafer surface grinding method P of the present invention.

As described above, according to the wafer surface grinding method of the present invention, it is possible to obtain a wafer that has been ground on both sides and that has no residual support-fixing resin removed from the edge portion. It can be suitably processed in S4.

EXAMPLES The present invention will be specifically described below using Examples and Comparative Examples, but the present invention is not limited to these.

In Example 1 and Comparative Example 1 described below, wafers were processed roughly by the method shown in the flow chart of FIG. The slicing step S1 and the chamfering step S2 are means for preparing the wafer as described above, and the same procedures were used in the first example and the first comparative example. Next, in Example 1, the double-sided grinding step S3-1 was performed in the procedure described below with reference to FIG. On the other hand, in Comparative Example 1, the double-sided grinding step S3-1 was performed in the procedure described below with reference to FIG. That is, Example 1 differs from Comparative Example 1 in the double-sided grinding step S3-1. Then, in Example 1 and Comparative Example 1, the double-side grinding step S3-1 was followed by the similar cleaning step S3-2. Finally, in Example 1 and Comparative Example 1, following the cleaning step S3-2, a similar etching step S4 was performed.
Each step performed in Example 1 and Comparative Example 1 is described below.

(Slicing step S1)
A silicon single crystal ingot with a diameter of 301 mm was prepared. A work piece having a thickness of 816 μm was cut out from this ingot by slicing with a wire saw.

(Chamfering step S2)
The workpiece was chamfered to prepare a wafer having a first principal surface and a second principal surface opposite to the first principal surface as shown in FIG. 2(A). The prepared wafer had an outermost edge (edge) located between the first and second major surfaces, which was formed by a chamfering process.

(Double-sided grinding step S3-1)
[Example 1]
<Formation s1 of release agent layer>
A part of the second main surface and the edge of the wafer were coated with a release agent to form a release agent layer (step s1). As the release agent, a silicone-based release agent (KF412SP) manufactured by Shin-Etsu Chemical Co., Ltd. was used.

Here, the range from the edge of the outermost periphery of the wafer to 1 mm was defined as the edge portion, and the release agent was applied so as to completely cover the edge portion with the release agent layer.

On the other hand, the release agent was applied to the second main surface so that the concentric release agent layer covered about 80% of the second main surface. The thickness of the release agent layer was 20 nm.

<Resin application s2 and film attachment s3>
Next, a resin was applied so as to cover the entire surface of the second main surface and the edge portion of the wafer (step s2). As the resin, an ultraviolet curable resin was used. The thickness was 100 μm. This formed a resin layer in contact with the wafer and the release agent layer. Next, a film (material: PET, thickness: 20 nm) as a base member was attached to the surface of the resin layer that was not in contact with the release agent layer (step s3). Then, the resin of the resin layer was cured. A wafer composite was thus obtained.

<First Main Surface Grinding s4>
Next, the first major surface of the wafer was surface-ground while the wafer composite was fixed by a vacuum chuck at the lower surface of the film (step s4).

<Film removal s5>
Next, the film was removed by a film remover device from the wafer having the ground first main surface (step s5).

<Second Main Surface Grinding s6>
Next, while the wafer was fixed at the position of the ground first main surface, the second main surface of the wafer was surface-ground (step s6).

[Comparative Example 1]
As shown in FIG. 8, the same step as the double-side grinding step S3-1 of Example 1 except that the resin is directly applied to the second main surface and the edge portion of the wafer without performing the release agent application step s1. did

(Washing step S3-2)
After the double-sided grinding step S3-1, the edge portion of the wafer was cleaned with a brush (step S3-2). At the same time, dirt on the ground first principal surface and the ground second principal surface of the wafer was removed by washing.

(Etching step S4)
After the cleaning step S3-2, the wafer was subjected to etching (step S4). Etching was performed by acid etching.

According to the series of steps of Example 1 described above, 20 etched wafers were obtained. Similarly, according to the series of steps of Comparative Example 1 described above, 20 etched wafers were obtained.

[evaluation]
(Film peelability test)
In the film removing step s5, the easiness of peeling of the film was evaluated. As a result, in Example 1, the film could be peeled off with a small force, and the film could be peeled off more easily than in Comparative Example 1. On the other hand, Comparative Example 1 required a relatively large force to peel off the film, resulting in cracks in 30% of the wafers obtained.

(resin residue evaluation)
After the etching step S4, the edge of the wafer was observed using a wafer inspection device CV350 manufactured by KLA-Tencor. Observations were made in ph mode. Based on this observation, the residual resin on the edge portion was evaluated.

9 and 10 are enlarged images (longitudinal magnification 150% UP images) of the edge portion from the side surface of each different wafer after double-sided grinding obtained in Example 1. FIG. 11 and 12 are enlarged images (longitudinal magnification 150% UP images) of edge portions of different wafers after double-sided grinding obtained in Comparative Example 1, viewed from the side surface.

9 and 10 and FIGS. 11 and 12, it can be seen that in Example 1, the resin on the edge portion was removed more than in Comparative Example 1. FIG.

The above evaluations are summarized in Table 1 below.

From the results described above, it can be seen that according to Example 1, the removal of the film from the wafer composite is facilitated, and workability is improved. Further, according to Example 1, cracking of the wafer can be suppressed, and the resin remaining on the edge portion can be sufficiently removed.

On the other hand, in Comparative Example 1 in which no release agent layer was formed, the adhesion between the wafer and the resin layer was too high, making it difficult to remove the film from the wafer composite, resulting in cracking of the wafer. It is thought that Moreover, in Comparative Example 1, it is considered that the adhesive strength between the edge portion of the wafer and the resin layer was too high, so that the resin remained on the edge portion.

It should be noted that the present invention is not limited to the above embodiments. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

REFERENCE SIGNS LIST 1, 1A, 1B, 1C, 1a and 1b Wafer 2 Release agent layer 3 Resin layer 4 Base member 5 Workpiece 10 Wafer composite 11 First main surface 11A and 11a... ground first major surface 11E and 11e... edge adjacent portion 12... second major surface 12A and 12a... ground second major surface 12E and 12e... edge adjacent portion 13 Edge part 13E Outermost edge 20 Part of release agent layer 23 Part of release agent layer 31 Base contact surface 32 Release agent contact surface 33 Resin layer part.

Claims (8)

A wafer surface grinding method,
An edge portion having a first principal surface and a second principal surface opposite to the first principal surface and located between the first principal surface and the second principal surface by the slicing step and the chamfering step providing a wafer comprising
applying a release agent to a portion of the second main surface and the edge of the wafer to form a release agent layer;
forming a resin layer covering the second main surface and the entire edge portion on the release agent layer;
disposing a base member on the resin layer to obtain a wafer composite;
Grinding the first major surface of the wafer while supporting and fixing the wafer composite at the position of the base member;
removing the base member from the wafer composite;
Grinding the second main surface of the wafer while supporting and fixing the wafer at the position of the ground first main surface;
and cleaning the wafer to remove the release agent layer and the resin layer remaining on the edge portion of the wafer. 2. The surface grinding method according to claim 1, wherein said edge portion is in a range of 2 mm or less from the edge of the outermost periphery of said wafer, and said mold release agent is applied to said edge portion. 3. The surface grinding method according to claim 2, wherein the edge portion is set to a range of 0.3 mm from the outermost edge of the wafer, and the release agent is applied to the edge portion. The surface grinding method according to any one of claims 1 to 3, wherein the release agent is applied so as to cover 30% or more and less than 100% of the second main surface of the wafer. The release agent layer is formed on the second main surface of the wafer in a lattice, linear, radial, dotted, concentric, spiral, broken line, or checkered pattern. The surface grinding method according to any one of claims 1 to 4. 6. The mold release agent according to any one of claims 1 to 5, wherein any one of silicone-based, long-chain alkyl-based, fluorine-based, aliphatic amide-based, and silica-based release agents is used. Surface grinding method. The surface grinding method according to any one of claims 1 to 6, wherein the release agent is applied only to the part and the edge portion of the second main surface of the wafer. The surface grinding method according to any one of claims 1 to 7, wherein the cleaning is performed by brush cleaning or two-fluid cleaning.

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