JP7528538B2 - Dicing Sheet - Google Patents

Description

The present invention relates to a dicing sheet.

The manufacturing process for semiconductor chips includes a dicing process in which a semiconductor wafer is cut. In the dicing process, an adhesive dicing sheet is attached to one side of the semiconductor wafer to hold and protect the semiconductor wafer. It is preferable that the dicing sheet is easily peeled off in a process after the dicing process. Patent Document 1 discloses the configuration of an adhesive sheet that includes thermally expandable microparticles in a laminated structure so that the sheet can be easily peeled off by heating in a later process.

JP 2008-45011 A

Such pressure-sensitive adhesive sheets may require a large amount of energy for heating in a post-process.
An object of the present invention is to provide a dicing sheet that can be efficiently peeled off from an object by heating.

The dicing sheet according to the present invention is a dicing sheet that peels off when heated, and includes an adhesive layer that adheres to an object, and a resin layer that is laminated to the adhesive layer and is made of low-temperature extruded resin, and the resin layer includes a foaming agent that foams when heated.

The dicing sheet is efficiently peeled off from the target by heating.

FIG. 2 is a plan view showing a state in which a semiconductor wafer is placed on a dicing sheet. FIG. 2 is a plan view showing a state in which the semiconductor wafer is diced. 2 is a cross-sectional view taken along line D3-D3 in FIG. 1 . 1 is a table showing the results of evaluation tests of the examples. 13 is a table showing evaluation test results of comparative examples.

(One example of the form that the dicing sheet can take)
[1] The dicing sheet according to the present invention is a dicing sheet that is peeled off by heating, the dicing sheet including an adhesive layer that adheres to an object, and a resin layer that is laminated to the adhesive layer and is composed of a low-temperature extruded resin, the resin layer including a foaming agent that foams by heating.
According to this dicing sheet, the foaming agent is contained in the resin layer made of low-temperature extrusion resin with a low melting point, so when the dicing sheet is heated, the foaming agent foams with a relatively low amount of heat, which allows the sheet to be efficiently peeled off from the target by heating.

[2] According to one example of the dicing sheet, the foaming agent is a microcapsule, and the microcapsule has an expansion ratio of 5 times or more.
According to this dicing sheet, the microcapsules have an expansion ratio of 5 times or more, so that the dicing sheet can be peeled off efficiently by heating.

[3] According to one example of the dicing sheet, the foaming start temperature of the microcapsules is 16° C. or more higher than the melting point temperature of the low-temperature extrusion resin.
This dicing sheet can prevent the microcapsules contained in the resin layer from foaming when the resin layer is extruded.

[4] According to one example of the dicing sheet, the diameter of the microcapsules is within the range of 5 to 50 μm.
According to this dicing sheet, the microcapsules have an appropriate expansion ratio, so that the dicing sheet can be suitably peeled off after heating.

[5] According to one example of the dicing sheet, the weight percentage of the foaming agent is in the range of 0.9 to 5.1 weight percent of the resin layer.
According to this dicing sheet, the foaming agent is suitably dispersed in the three-dimensional structure of the resin layer, which allows the dicing sheet to be suitably peeled off after heating.

[6] According to one example of the dicing sheet, the thickness of the resin layer in the lamination direction is within a range of 9 to 110 μm.
This dicing sheet allows for favorable heat conduction to the resin layer.

[7] According to one example of the dicing sheet, the dicing sheet further includes a support layer that supports the resin layer.
This dicing sheet can favorably support the adhesive layer and the resin layer.

[8] According to one example of the dicing sheet, the dicing sheet further includes a protective layer that protects the adhesive layer.
This dicing sheet can provide suitable protection for the adhesive layer prior to use.

(Embodiment)
A dicing sheet 10 according to an embodiment will be described with reference to FIGS. 1 to 3. The dicing sheet 10 is used in the manufacturing process of the semiconductor chip 101. The manufacturing process of the semiconductor chip 101 includes a pre-process and a post-process. The pre-process includes a film-forming process for forming a thin film layer on the semiconductor wafer 100, a pattern transfer process for applying a photosensitive agent onto the thin film layer and transferring a circuit pattern, and an etching process for processing the thin film into a shape such as wiring. The post-process includes a dicing process for cutting the semiconductor wafer 100 and separating the semiconductor chip 101, and a packaging process for fixing the semiconductor chip 101 at a predetermined position. The dicing sheet 10 is used in the dicing process. The dicing sheet 10 is a sheet having a function of holding and protecting the semiconductor wafer 100 in the dicing process. Holding the semiconductor wafer 100 includes suppressing relative positional deviation during cutting with a dicing saw. Protecting the semiconductor wafer 100 includes suppressing adhesion of dust and the like to the semiconductor wafer 100 and the semiconductor chip 101 in the dicing process. The semiconductor wafer 100 is formed into, for example, a circular or elliptical shape, and the semiconductor chip 101 is formed into, for example, a square shape.

As shown in FIG. 3, the dicing sheet 10 includes an adhesive layer 20 and a resin layer 30. The adhesive layer 20 adheres to a predetermined object. The predetermined object is, for example, a semiconductor wafer 100 and a semiconductor chip 101. The adhesive layer 20 adheres to the semiconductor wafer 100 at the surface 20A and holds the semiconductor wafer 100. There is almost no gap between the surface 20A and the semiconductor wafer 100. In the following, the side of the adhesive layer 20 on which the semiconductor wafer 100 is placed may be referred to as the inside, and the side opposite to the side on which the semiconductor wafer 100 is placed may be referred to as the outside. The resin layer 30 protects the semiconductor wafer 100. The resin layer 30 is laminated on the outside of the adhesive layer 20.

The adhesive layer 20 is made of a pressure-sensitive adhesive. The pressure-sensitive adhesive is, for example, at least one of an acrylic adhesive made of an acrylic polymer, a urethane adhesive made of polyurethane, a silicon adhesive made of a silicon polymer, and a rubber adhesive. The adhesive layer 20 is made of one or more layers. The multiple layers may be configured so that the types of pressure-sensitive adhesives that constitute them are different from one another. The adhesive strength between the semiconductor wafer 100 or the semiconductor chip 101 and the adhesive layer 20 is preferably such that the adhesive strength is not peeled off during the dicing process, and is easily peeled off when the adhesive strength is reduced by heating after the dicing process. In one example, the adhesive strength between the semiconductor wafer 100 and the adhesive layer 20 is 0.1 N/15 mm or more. Preferably, the adhesive strength between the semiconductor wafer 100 and the adhesive layer 20 is 0.5 N/15 mm or more. The adhesive strength between the semiconductor wafer 100 and the adhesive layer 20 is 7 N/15 mm or less. Preferably, the adhesive strength between the semiconductor wafer 100 and the adhesive layer 20 is 3 N/15 mm or less. In one example, the adhesive strength between the semiconductor wafer 100 and the adhesive layer 20 is 2.0 N/15 mm. The adhesive strength between the semiconductor wafer 100 and the adhesive layer 20 is weaker than the adhesive strength between the resin layer 30 and the adhesive layer 20. In one example, the adhesive strength between the resin layer 30 and the adhesive layer 20 is 7 N/15 mm or more. Preferably, the adhesive strength between the resin layer 30 and the adhesive layer 20 is 15 N/15 mm or more. The thickness of the adhesive layer 20 in the stacking direction is preferably 30 μm or less.

The resin layer 30 is made of resin. The resin is, for example, a synthetic resin. The synthetic resin is, for example, a thermoplastic resin. The thermoplastic resin is preferably a low-temperature extrusion resin whose melting point temperature is equal to or lower than a predetermined temperature. The predetermined temperature is, for example, 130°C. The thermoplastic resin is, for example, polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and ethylene vinyl acetate polymer (EVA). Polyethylene includes low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE). The thickness of the resin layer 30 in the stacking direction is preferably 9 μm or more. More preferably, the thickness of the resin layer 30 in the stacking direction is 10 μm or more. The thickness of the resin layer 30 in the stacking direction is preferably 110 μm or less. More preferably, the thickness of the resin layer 30 in the stacking direction is 100 μm or less.

The resin layer 30 further includes a foaming agent 40. The foaming agent 40 is configured to foam when a predetermined condition is applied. An example of the predetermined condition is heating. Another example of the predetermined condition is irradiation with ultraviolet light. In one example, the foaming agent 40 is a microcapsule 41 that encapsulates a gas that foams when a predetermined condition is applied. In another example, the foaming agent 40 includes a chemical that releases a gas when a predetermined condition is applied. In one example, the foaming agent 40 is azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), and baking soda. In this embodiment, the foaming agent 40 is a microcapsule 41. The weight percentage of the foaming agent 40 relative to the resin layer 30 is preferably 0.9 weight percent or more. More preferably, it is 1.0 weight percent or more. The weight percentage of the foaming agent 40 relative to the resin layer 30 is preferably 5.1 weight percent or less. More preferably, it is 5.0 weight percent or less. The foaming agent 40 is mixed with the resin that constitutes the resin layer 30 by any commonly known means. In one example, it is mixed by a dry blending method. In another example, it is mixed by a melt blending method.

The appropriate shape, size, and contents of the microcapsules 41 are determined by the expansion ratio and the thickness of the resin layer 30. The microcapsules 41 are formed in a circular shape with a diameter of, for example, 5 μm to 50 μm. The microcapsules 41 have an outer shell and an internal space. The outer shell is made of, for example, a thermoplastic resin. The thickness of the outer shell is made to be 2 μm to 15 μm. The internal space contains a gas or liquid that expands when heated. In one example, the internal space contains a hydrocarbon. The expansion start temperature of the microcapsules 41 is higher than the melting point temperature of the resin that constitutes the resin layer 30. At the expansion start temperature, the outer shell of the microcapsules 41 becomes soft, and the microcapsules 41 expand with the expansion of the gas in the internal space. The expansion ratio of the microcapsules 41 is preferably 5 times or more. The expansion ratio is determined by the volume of the microcapsules 41 after expansion relative to the volume of the microcapsules 41 before expansion. Preferably, the foaming start temperature of the microcapsules 41 is 16°C or more higher than the melting point temperature of the resin that constitutes the resin layer 30. More preferably, the foaming start temperature of the microcapsules 41 is 20°C or more higher than the melting point temperature of the resin that constitutes the resin layer 30.

The dicing sheet 10 further includes a support layer 50 that supports the adhesive layer 20 and the resin layer 30. The support layer 50 is laminated on the outside of the resin layer 30. The support layer 50 may have any configuration. In one example, the support layer 50 is made of PET. In another example, the support layer 50 is made of recycled paper or non-recycled paper. The thickness of the support layer 50 in the lamination direction is preferably the same as that of the resin layer 30. The support layer 50 and the resin layer 30 are laminated together, for example, by a layer containing a pressure-sensitive adhesive.

The inventors of the present application conducted an evaluation test to evaluate the detachment stability of the dicing sheet 10 of the embodiment. In the evaluation test, a semiconductor chip 101 was placed on the adhesive layer 20 of each dicing sheet 10 of the example and comparative example, and heated for one minute at a temperature 50°C higher than the foaming start temperature of the foaming agent 40. After heating, the detachment stability between the dicing sheet 10 and the semiconductor chip 101 was evaluated. Specifically, the surface 20A of the dicing sheet 10 was rotated 90° from the horizontal state, and if the semiconductor chip 101 peeled off from the dicing sheet 10, it was determined that the dicing sheet had detachment stability.

In the evaluation test, dicing sheets 10 of several examples and comparative examples were prepared. In the dicing sheets 10 of several examples and comparative examples, at least one of the following was changed: the type of resin constituting the resin layer 30, the extrusion resin temperature when molding the resin layer 30, the thickness of the resin layer 30 in the lamination direction, the type of foaming agent 40, and the compounding ratio. The types of foaming agents 40 used were foaming agents A to H containing microcapsules 41 with at least one different expansion ratio, foaming start temperature, and stable foaming temperature. All of the foaming agents A to H are commercially available foaming agents 40. A total of 30 dicing sheets 10 were prepared and subjected to the comparison test. The inventor of the present application judged the dicing sheets 10 to be "good" when all 30 sheets have desorption stability and are judged to have no other problems. The inventor of the present application judged the dicing sheets 10 to be "defective" when one or more of the 30 sheets do not have desorption stability. The inventor of the present application judged the dicing sheets 10 to be "bad" when one or more of the 30 sheets do not have desorption stability and are considered to have a problem in using the dicing sheets 10.

In the dicing sheet 10 of Example 1, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent F with an expansion ratio of 5 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 2, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 10 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 3, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 4, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 100 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 5, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 100 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 6, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 7, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 5%.

In the dicing sheet 10 of Example 8, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 9, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 10, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 11, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The compounding ratio of the foaming agent 40 is 5%.

In the dicing sheet 10 of Example 12, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent C with an expansion ratio of 12 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 13, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent C with an expansion ratio of 12 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 14, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent C with an expansion ratio of 12 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 15, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent C with an expansion ratio of 12 times. The compounding ratio of the foaming agent 40 is 5%.

In the dicing sheet 10 of Example 16, the resin layer 30 is made of EVA with a melting point temperature of 110°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 120°C, and the foaming agent 40 contains foaming agent D with an expansion ratio of 10 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 17, the resin layer 30 is made of EVA with a melting point temperature of 110°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 120°C, and the foaming agent 40 contains foaming agent D with an expansion ratio of 10 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 18, the resin layer 30 is made of EVA with a melting point temperature of 110°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 120°C, and the foaming agent 40 contains foaming agent D with an expansion ratio of 10 times. The compounding ratio of the foaming agent 40 is 5%.

In the dicing sheet 10 of Example 19, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 20, the resin layer 30 is made of EVA with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 21, the resin layer 30 is made of EVA with a melting point temperature of 120°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 130°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 22, the resin layer 30 is made of PE with a melting point temperature of 120°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 130°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 23, the resin layer 30 is made of PE with a melting point temperature of 125°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 135°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 24, the resin layer 30 is made of PE with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 10 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 25, the resin layer 30 is made of PE with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Example 26, the resin layer 30 is made of PE with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 100 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 27, the resin layer 30 is made of PE with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Example 28, the resin layer 30 is made of PE with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The compounding ratio of the foaming agent 40 is 0.9%.

In the dicing sheet 10 of Comparative Example 1, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent H with an expansion ratio of 3 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 2, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent G with an expansion ratio of 4 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 3, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 70°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 4, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 0.5%.

In the dicing sheet 10 of Comparative Example 5, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 0.9%.

In the dicing sheet 10 of Comparative Example 6, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 5 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Comparative Example 7, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 9 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 1%.

In the dicing sheet 10 of Comparative Example 8, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 110 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 9, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 150 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 10, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 5.1%.

In the dicing sheet 10 of Comparative Example 11, the resin layer 30 is made of EVA with a melting point temperature of 70°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 80°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The compounding ratio of the foaming agent 40 is 7%.

In the dicing sheet 10 of Comparative Example 12, the resin layer 30 is made of EVA with a melting point temperature of 71°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 81°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The foaming start temperature of foaming agent A is 90°C, and the difference between the foaming start temperature and the melting point temperature is 19°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 13, the resin layer 30 is made of EVA with a melting point temperature of 74°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 84°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The foaming start temperature of foaming agent A is 90°C, and the difference between the foaming start temperature and the melting point temperature is 16°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 14, the resin layer 30 is made of EVA with a melting point temperature of 75°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 85°C, and the foaming agent 40 contains foaming agent A with an expansion ratio of 9 times. The foaming start temperature of foaming agent A is 90°C, and the difference between the foaming start temperature and the melting point temperature is 15°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 15, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The foaming start temperature of foaming agent B is 100°C. The compounding ratio of foaming agent 40 is 0.9%.

In the dicing sheet 10 of Comparative Example 16, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The foaming start temperature of foaming agent B is 100°C. The compounding ratio of foaming agent 40 is 5.1%.

In the dicing sheet 10 of Comparative Example 17, the resin layer 30 is made of EVA with a melting point temperature of 80°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 90°C, and the foaming agent 40 contains foaming agent B with an expansion ratio of 11 times. The foaming start temperature of foaming agent B is 100°C. The compounding ratio of foaming agent 40 is 6%.

In the dicing sheet 10 of Comparative Example 18, the resin layer 30 is composed of PE with a melting point temperature of 120°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 130°C, and the foaming agent 40 contains foaming agent D with an expansion ratio of 10 times. The foaming start temperature of foaming agent D is 130°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent D is 10°C. The compounding ratio of foaming agent 40 is 1%.

In the dicing sheet 10 of Comparative Example 19, the resin layer 30 is composed of PE with a melting point temperature of 120°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 130°C, and the foaming agent 40 contains foaming agent D with an expansion ratio of 10 times. The foaming start temperature of foaming agent D is 130°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent D is 10°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 20, the resin layer 30 is composed of PE with a melting point temperature of 120°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 120°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The foaming start temperature of foaming agent E is 150°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent E is 30°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 21, the resin layer 30 is composed of PE with a melting point temperature of 130°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 140°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The foaming start temperature of foaming agent E is 150°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent E is 20°C. The compounding ratio of foaming agent 40 is 5.1%.

In the dicing sheet 10 of Comparative Example 22, the resin layer 30 is composed of PE with a melting point temperature of 131°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 141°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The foaming start temperature of foaming agent E is 150°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent E is 19°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 23, the resin layer 30 is composed of PE with a melting point temperature of 134°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 144°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The foaming start temperature of foaming agent E is 150°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent E is 16°C. The compounding ratio of foaming agent 40 is 3%.

In the dicing sheet 10 of Comparative Example 24, the resin layer 30 is composed of PE with a melting point temperature of 135°C. The thickness of the resin layer 30 in the lamination direction is 75 μm. The extrusion resin temperature when molding the resin layer 30 is 145°C, and the foaming agent 40 contains foaming agent E with an expansion ratio of 8 times. The foaming start temperature of foaming agent E is 150°C, and the difference between the foaming start temperature and the melting point temperature of foaming agent E is 15°C. The compounding ratio of foaming agent 40 is 3%.

The dicing sheet 10 of Comparative Example 25 does not include a resin layer 30. The thickness of the adhesive layer 20 in the lamination direction is configured to be 75 μm. The adhesive layer 20 includes an adhesive that starts to foam between 120 and 150°C. The foaming ratio is 10 times.

The results of the evaluation test will be described with reference to FIG. 4 and FIG.
The dicing sheets 10 of Examples 1 to 28 were all evaluated as "good" and had detachment stability. On the other hand, the dicing sheets 10 of Comparative Examples 1 to 25 were evaluated as "good" or "bad", meaning that they did not have detachment stability or other problems arose in the dicing sheets 10.

The findings obtained from the results of the evaluation test will be explained below.
From the results of Comparative Example 1 and Comparative Example 2, it is preferable that the foaming ratio is a predetermined ratio or more. The predetermined ratio is, for example, 5 times or more. If the predetermined ratio is less than 5 times, foaming is insufficient, and the adhesive layer 20 may not be detached from the semiconductor wafer 100.

From the results of Comparative Examples 6 to 9, it is preferable that the thickness of the resin layer 30 in the stacking direction is within a predetermined range. The thickness of the resin layer 30 in the stacking direction is preferably 9 μm or more. More preferably, the thickness of the resin layer 30 in the stacking direction is 10 μm or more. The thickness of the resin layer 30 in the stacking direction is preferably 110 μm or less. More preferably, the thickness of the resin layer 30 in the stacking direction is 100 μm or less. If the thickness of the resin layer 30 in the stacking direction is less than 9 μm, the resin layer 30 cannot be extrusion molded. If the thickness of the resin layer 30 in the stacking direction is greater than 110 μm, the thermal conductivity of the resin layer 30 decreases, and the foaming agent 40 may not foam sufficiently.

From the results of Comparative Examples 4, 5, 10, 11, 15 to 17 and Comparative Example 21, it is preferable that the weight percentage of the foaming agent 40 relative to the resin layer 30 is within a predetermined range. The weight percentage of the foaming agent 40 relative to the resin layer 30 is preferably 0.9 weight% or more. More preferably, it is 1.0 weight% or more. The weight percentage of the foaming agent 40 relative to the resin layer 30 is preferably 5.1 weight% or less. More preferably, it is 5.0 weight% or less. If the weight percentage of the foaming agent 40 relative to the resin layer 30 is less than 0.9 weight%, the effect of the foaming agent 40 may not be sufficient. If the weight percentage of the foaming agent 40 relative to the resin layer 30 is more than 5.1 weight%, the foaming agent 40 may separate in the resin layer 30.

From the results of Comparative Examples 12 to 15, 18, and 19 and Comparative Examples 22 to 24, it is preferable that the foaming start temperature of the foaming agent 40 is a predetermined temperature or higher than the melting point temperature of the resin that constitutes the resin layer 30. The foaming start temperature of the foaming agent 40 is preferably 16°C or higher than the melting point temperature of the resin that constitutes the resin layer 30. More preferably, the foaming start temperature of the foaming agent 40 is 20°C or higher than the melting point temperature of the resin that constitutes the resin layer 30. If the difference between the foaming start temperature of the foaming agent 40 and the melting point temperature of the resin that constitutes the resin layer 30 is less than 16°C, foaming may occur during extrusion molding of the resin layer 30. In this case, unevenness is formed on the surface 20A of the adhesive layer 20, and the adhesive strength decreases.

The results of Comparative Example 3 and Comparative Example 20 show that the extrusion resin temperature needs to be higher than the melting point temperature by a predetermined temperature or more. The predetermined temperature is, for example, 10°C. Furthermore, the results of Comparative Example 25 show that including a foaming adhesive in the adhesive layer 20 reduces the release stability.

The function of the dicing sheet 10 of the embodiment will be described.
In the dicing process, the adhesive layer 20 of the dicing sheet 10 and the semiconductor wafer 100 are adhered to each other, and the semiconductor wafer 100 is held and protected. The semiconductor wafer 100 is cut by a dicing saw to form a plurality of semiconductor chips 101. The dicing sheet 10 adhered to the semiconductor chips 101 is heated, and the foaming agent 40 of the resin layer 30 is foamed. The foaming of the foaming agent 40 forms unevenness on the surface 20A of the resin layer 30 and the adhesive layer 20. The unevenness of the surface 20A reduces the adhesive strength between the surface 20A and the semiconductor chip 101. In one example, the adhesive strength is less than 0.1 N/15 mm. Therefore, the dicing sheet 10 and the semiconductor chip 101 are easily peeled off from each other.

(Modification)
The description of the embodiments is merely an example of possible forms of the dicing sheet according to the present invention, and is not intended to limit the forms. The dicing sheet according to the present invention may take a form other than the embodiments, for example, modified forms of the embodiments shown below, or a combination of at least two mutually compatible modified forms.

- The dicing sheet 10 may further include a protective layer that protects the adhesive layer 20. The protective layer is laminated on the inside of the adhesive layer 20 and protects the adhesive layer 20 until the semiconductor wafer is placed on it. The protective layer is made of, for example, PET, biaxially oriented polypropylene film (OPP), or synthetic paper.

The adhesive layer 20 may be configured to be peeled off from the semiconductor chip 101 by a means other than heating. In one example, the adhesive layer 20 is configured to be peeled off from the surface 20A of the adhesive layer 20 and the semiconductor chip 101 by irradiation with ultraviolet rays. The adhesive layer 20 is configured to change its three-dimensional structure by irradiation with ultraviolet rays.
As another example, the specified target may include at least one of an electrical item such as a ceramic capacitor or an oscillator, a liquid crystal solar cell, and a printed circuit board.

- The support layer 50 may further include an adhesive layer that adheres to the metal and a protective layer that protects the adhesive layer. The adhesive layer includes a pressure-sensitive adhesive. The protective layer protects the adhesive layer.

REFERENCE SIGNS LIST 10 dicing sheet 20 adhesive layer 30 resin layer 40 foaming agent 50 support layer 100 semiconductor wafer 101 semiconductor chip

Claims (7)

A dicing sheet that is peeled off by heating,
The dicing sheet has an adhesive layer that adheres to an object;
A resin layer laminated on the adhesive layer and made of a low-temperature extruded resin;
The resin layer contains a foaming agent that foams upon heating,
The foaming agent is a microcapsule,
The foaming start temperature of the microcapsules is 20° C. or more higher than the melting point temperature of the low-temperature extrusion resin.
Dicing sheet. The dicing sheet according to claim 1 , wherein the microcapsules have an expansion ratio of 5 times or more. The diameter of the microcapsules is within the range of 5 to 50 μm.
The dicing sheet according to claim 1 or 2 . The weight percent of the foaming agent is in the range of 0.9 to 5.1 weight percent of the resin layer.
The dicing sheet according to any one of claims 1 to 3 . The thickness of the resin layer in the lamination direction is within a range of 9 to 110 μm.
The dicing sheet according to any one of claims 1 to 4 . The resin layer may further include a support layer.
The dicing sheet according to any one of claims 1 to 5 . The adhesive layer may further include a protective layer.
The dicing sheet according to any one of claims 1 to 6 .