JP2009246195A - Adhesive sheet and processing method of semiconductor wafer using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in a yield of a semiconductor chip by backgrinding, or the like by increasing adhesive strength to a semiconductor wafer. <P>SOLUTION: An adhesive sheet S includes a base material sheet BS, and an adhesive layer A stacked onto one surface of the base material sheet BS, and is protectably pasted to the side of a circuit surface W1 of the semiconductor wafer W. The adhesive layer A includes a recess C. Adhesive strength of a bottom surface C1 at the recess C is set to be weaker than that of the adhesive layer A forming the outside of the recess C. The recess C is provided in a planar shape corresponding to the shape of a pattern P1 formed in the semiconductor wafer W, and an adhesive region to the semiconductor wafer W is secured widely. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive sheet and a semiconductor wafer processing method using the same, and more specifically, prevents damage to the semiconductor wafer in a semiconductor wafer processing step such as backside grinding, and prevents a decrease in yield of semiconductor chips. The present invention relates to an adhesive sheet that can be used and a semiconductor wafer processing method using the same.

  As a semiconductor wafer (hereinafter simply referred to as “wafer”), there is a type in which solder bumps (hereinafter referred to as “bumps”) for ensuring electrical conduction are formed on the circuit surface side. In addition, the wafer is subjected to a process such as back grinding by attaching a protective adhesive sheet to the circuit surface side. Patent Document 1 discloses an adhesive sheet that does not cause variation in the thickness after back surface grinding by a bump even if the wafer has bumps formed thereon. This adhesive sheet includes a base sheet that has substantially the same planar shape as the wafer, and an adhesive layer laminated on one surface of the base sheet, and the adhesive layer extends along the outer edge of the base sheet. It is provided with a certain width so that it does not overlap bumps or circuit patterns.

JP 2005-123382 A

  However, in such a configuration, since the width of the adhesive layer is several millimeters, the adhesive force may not be sufficient. As a result, there is an inconvenience that the adhesion is released by an external force from a grinder or the like when the back surface of the wafer is ground, and the wafer is displaced from the protective sheet. As a result, there is a disadvantage that the yield of the semiconductor chip is lowered due to damage of the wafer or foreign matters such as grinding cleaning water mixed with the adhesive sheet.

[Object of invention]
The present invention has been devised by paying attention to such inconveniences, and its purpose is to increase the adhesive force with the wafer and prevent the semiconductor wafer from being damaged during the processing of the semiconductor wafer such as back surface grinding. Another object of the present invention is to provide an adhesive sheet that can prevent a reduction in the yield of semiconductor chips and a semiconductor wafer processing method using the adhesive sheet.

In order to achieve the above object, the present invention provides an adhesive sheet for attaching to a circuit surface side of a semiconductor wafer,
A base sheet, and an adhesive layer laminated on one surface of the base sheet,
The adhesive layer includes a recess corresponding to the pattern shape formed on the semiconductor wafer, and the bottom surface of the recess is set to have a weaker adhesive force than the adhesive layer forming a portion other than the recess. ing.

Further, the present invention provides an adhesive sheet for attaching to the circuit surface side of a semiconductor wafer,
A base sheet, and an adhesive layer laminated on one surface of the base sheet,
It includes a recess corresponding to the pattern shape formed on the semiconductor wafer, and the recess is not provided with the adhesive layer.

  In the present invention, the adhesive layer is preferably made of an energy ray curable adhesive.

  The depth of the concave portion may be set to a depth corresponding to the height from a position where there is no pattern on the semiconductor wafer to the apex of the bump formed on the pattern.

  Further, a configuration in which the outer edge shape is the same as or smaller than the outer edge shape of the semiconductor wafer is preferably employed.

  The semiconductor wafer processing method of the present invention employs a method in which the semiconductor wafer is subjected to predetermined processing after the adhesive sheet according to any one of claims 1 to 5 is attached to the semiconductor wafer.

  According to the present invention, since the adhesive layer has a recess corresponding to the pattern shape formed on the wafer, the adhesion area between the wafer and the adhesive layer outside the outer edge of the pattern can be enlarged. As a result, the wafer does not deviate from the adhesive sheet during backside grinding, and it is possible to prevent the yield of semiconductor chips from decreasing. Further, since the bottom surface of the recess is set to have a weak adhesive force, it is possible to prevent inconveniences such as peeling off the bumps when the adhesive sheet is peeled off. The same effect can be obtained by not providing the adhesive layer in the concave portion corresponding to the pattern shape formed on the semiconductor wafer.

  In addition, since the adhesive layer is made of an energy ray curable adhesive, the concave portion is irradiated with energy rays to prevent the adhesive in the concave portion from hardening and returning to its original shape or deformation. In addition, the adhesive force on the bottom surface of the recess can be reduced.

  Furthermore, since the depth of the concave portion is set as described above, it is possible to avoid variation in the thickness of the wafer after grinding due to the bumps when grinding the back surface of the wafer, and it is possible to perform accurate back surface grinding. .

  Further, when the outer edge shape of the adhesive sheet is formed to be the same as the outer edge shape of the wafer, it is possible to omit the process of attaching the adhesive sheet to the wafer and then cutting the adhesive sheet along the outer edge of the wafer. In addition, when the outer edge shape of the adhesive sheet is formed smaller than the outer edge shape of the wafer, in the wafer having a chamfered portion on the outer periphery, the outer periphery of the adhesive sheet becomes larger than the outer periphery of the wafer due to back grinding. Can be avoided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present specification and claims, “weak adhesive strength”, “adhesive strength is weak”, and “adhesive strength is reduced” are used as concepts including cases where no adhesive strength is provided.

  FIG. 1 is a plan view showing a state in which the adhesive sheet according to the embodiment is attached to a wafer, and FIG. 2 is a partial cross-sectional view taken along arrow a in FIG. In these drawings, the adhesive sheet S is affixed to the circuit surface W1 side of the wafer W before backside grinding whose planar shape is substantially circular.

  As shown in FIG. 3, the circuit surface W1 side of the wafer W is provided with a large number of patterns P1 formed corresponding to chips formed by cutting in a plane view in a later process. In P1, bumps B are provided at a plurality of locations.

  The adhesive sheet S includes a base sheet BS and an adhesive layer A laminated on one surface (the lower surface in FIG. 2) of the base sheet BS. The outer edge shape of the base sheet BS and the adhesive layer A is formed smaller than the outer edge shape of the wafer W, as shown in FIG. That is, the outer periphery of the adhesive sheet S becomes larger than the outer periphery of the wafer W along with the grinding of the wafer W by making the planar shape substantially the same as the planar portion excluding the chamfered portion of the wafer W. It is possible to prevent the wafer W from being damaged by being caught in the grindstone of the grinder. The adhesive layer A is made of an energy ray curable adhesive that is cured by energy rays such as ultraviolet rays and has a reduced adhesive force. Here, as also shown in FIG. 4, the adhesive layer A includes in-plane a recess C that is partially thin.

  In the case of the present embodiment, the concave portion C is formed by pressing with a pressing member (not shown) formed in a shape that entirely surrounds the plurality of patterns P1, as indicated by a two-dot chain line (symbol P) in FIG. Has been. The bottom surface C1 (upper surface side in FIG. 2) of the recess C is irradiated with ultraviolet rays, and the adhesive force is weaker than the adhesive layer A that forms the outside of the recess C. Further, as shown in FIG. 2, the depth D1 of the recess C corresponds to the height H1 from the position of the circuit surface W1 where the pattern P1 does not exist on the wafer W to the apex of the bumps B formed on the pattern P1. The depth is set to be substantially the same.

When the back surface of the wafer W is ground, as shown in FIG. 1, the adhesive sheet S is formed so that the recess C entirely surrounds the pattern P <b> 1 formed on the wafer W in order to protect the circuit surface W <b> 1 of the wafer W. Is affixed to the wafer W. In this attached state, the adhesive sheet S is placed so as to be held on a predetermined table (not shown), and then back grinding is performed using a grinder or the like. At this time, since the adhesive layer A is bonded to the wafer W in substantially the entire region except the pattern P1 of the wafer W, the adhesive force of the adhesive sheet S to the wafer W is dramatically improved as compared with the conventional example. Thus, it is possible to reliably prevent the wafer W from being displaced from or detached from the adhesive sheet S due to the external force due to the back surface grinding. As a result, it is possible to avoid contamination of foreign matters such as cleaning water for grinding between the wafer W and the adhesive sheet S, and it is possible to prevent a decrease in the yield of the semiconductor chips.
In addition, since the depth D1 of the concave portion C is set as described above, it is possible to avoid variation in thickness of the wafer after back grinding due to the bump. In addition, since the adhesive force of the bottom face C1 of the recessed part C is reduced, the inconvenience of peeling off the bumps B when the adhesive sheet S is peeled off after grinding is eliminated.

As described above, the best configuration, method, and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this.
In other words, the present invention has been illustrated and described mainly with respect to specific embodiments, but without departing from the scope of the technical idea and object of the present invention, the shape, position, or With respect to the arrangement and the like, those skilled in the art can make various changes as necessary.
Therefore, the description limited to the shape disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded one part or all part is included in this invention.

  For example, the concave portion C can be variously modified. For example, as shown in FIGS. 5 and 6, the concave portion C can be formed in a shape corresponding to each pattern P1. By adopting such a configuration, it is possible to make the bonding region between the patterns, so that the adhesive force of the adhesive sheet S to the wafer W can be increased, and the wafer W shifts and foreign matter during backside grinding. Inconveniences such as mixing can be prevented more effectively. The recess C can also be formed in a shape that partially surrounds the plurality of patterns P1.

  In the above embodiment, the bottom surface C1 of the recess C is flat. However, as shown in FIG. 7, the shape of the bottom surface C1 of the recess C corresponds to the shape of the pattern P1 and the bump B. The shape of the wafer W on the circuit surface W1 side may be transferred to the adhesive layer A.

  Furthermore, as shown in FIG. 8, the recess C may be formed by not laminating the adhesive layer A. By setting it as such a structure, the process of hardening the adhesive bond layer A with an energy ray and reducing an adhesive force becomes unnecessary.

  Further, as shown in FIG. 9, the belt-like adhesive sheet S may be formed with a recess C corresponding to the pattern shape. In this case, a strip-shaped release sheet RL may be provided to protect the adhesive layer A. In addition, when it is set as such a strip | belt-shaped adhesive sheet S, after sticking on the wafer W, the said adhesive sheet S should just be cut | disconnected and used for a predetermined shape.

  Further, in the above-described embodiment, the adhesive sheet S corresponding to the wafer W on which the bump B is formed is illustrated and described. However, the present invention is not limited to this, and the adhesive sheet S is not limited to this. It may be configured. In this case, the depth D1 of the recess C may be set to be substantially the same as the height from the position of the circuit surface W1 where the pattern P1 does not exist on the wafer W to the top of the pattern P1.

  The semiconductor wafer may be a silicon wafer or a compound wafer.

  Furthermore, the adhesive which comprises the adhesive bond layer A is not limited to an energy beam curing type adhesive, A well-known releasable adhesive can be used.

  Further, the adhesive sheet S is not limited to use as an adhesive sheet for back surface grinding, and is used by being attached to the semiconductor wafer in a predetermined processing process such as a polishing process or a dicing process. can do.

The top view in the state where the adhesive sheet concerning an embodiment was stuck on the wafer. FIG. The top view of a wafer. The schematic perspective view which looked at the adhesive sheet from the adhesive bond layer side. The schematic perspective view similar to FIG. 4 of the adhesive sheet which concerns on a 1st modification. FIG. 6 is a partial cross-sectional view taken along arrow b in FIG. 5 according to a first modification. The fragmentary sectional view of the adhesive sheet which concerns on a 2nd modification. The fragmentary sectional view of the adhesive sheet which concerns on a 3rd modification. The schematic perspective view of the adhesive sheet which concerns on a 4th modification.

Explanation of symbols

A Adhesive layer C Recess C1 Bottom BS Base sheet P1 Pattern B Bump S Adhesive sheet W Semiconductor wafer W1 Circuit surface

Claims (6)

In an adhesive sheet for attaching to the circuit surface side of a semiconductor wafer,
A base sheet, and an adhesive layer laminated on one surface of the base sheet,
The adhesive layer includes a recess corresponding to the pattern shape formed on the semiconductor wafer, and the bottom surface of the recess is set to have a weaker adhesive force than the adhesive layer forming a portion other than the recess. Adhesive sheet. In an adhesive sheet for attaching to the circuit surface side of a semiconductor wafer,
A base sheet, and an adhesive layer laminated on one surface of the base sheet,
An adhesive sheet comprising a recess corresponding to a pattern shape formed on the semiconductor wafer, wherein the adhesive layer is not provided in the recess.   The adhesive sheet according to claim 1, wherein the adhesive layer is made of an energy ray curable adhesive.   The depth of the concave portion is set to a depth corresponding to a height from a position where there is no pattern on the semiconductor wafer to the apex of the bump formed on the pattern. 3. The adhesive sheet according to 3.   5. The adhesive sheet according to claim 1, wherein the adhesive sheet is formed in an outer edge shape that is the same as or smaller than the outer edge shape of the semiconductor wafer.   A method for processing a semiconductor wafer, comprising: applying the adhesive sheet according to any one of claims 1 to 5 to a semiconductor wafer and then performing a predetermined process on the semiconductor wafer.

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