TW201513196A - Method for producing semiconductor package - Google Patents

Abstract

Provided is a method for producing a semiconductor package which makes it possible to suppress the occurrence of warping after grinding a sealed article obtained using a sealing resin sheet. The present invention is a method for producing a semiconductor package including a sealed-body formation step for forming a sealed body obtained by burying one or more semiconductor chips in a sealing resin sheet, and a grinding step for forming a grinded body by grinding the sealing resin sheet of the sealed body so as to expose the surface of the semiconductor chip opposite the active surface thereof, wherein the minimum height difference between the exposed surface of the semiconductor chip and the surface of the sealing resin sheet of the grinded body is 10[mu]m or more.

Description

Semiconductor package manufacturing method Technical field

The present invention relates to a method of fabricating a semiconductor package.

Background technique

In recent years, the demand for miniaturization, weight reduction, and high performance of electronic devices has increased. Therefore, it has been demanded to reduce the size, thickness, and density of packages constituting electronic devices.

In the production system of a semiconductor package, a step of sealing an electronic component fixed to a substrate, a temporary positioning material, or the like by a sealing resin and cutting the sealing material as necessary into a package of an electronic component unit is used. In such a process, in response to the above-mentioned request, a technique of polishing a seal after resin sealing and seeking to reduce the thickness has been proposed (for example, Patent Documents 1, 2, etc.). In flip chip BGA (Ball Grid Array), flip chip SiP (System in Package), fan-in wafer level package, fan-out wafer level package, etc. In the manufacturing steps of the thin semiconductor package, the thinning of such polishing is also an important factor.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent No. 3420748

Patent Document 2: Japanese Patent No. 3666576

Summary of invention

However, there is a case where warpage occurs in the sealed seal, and when the semiconductor package is produced in a state where warpage occurs, the yield is lowered, or the reliability of the obtained semiconductor package is lowered. This disadvantage is not recognized in the techniques of Patent Documents 1 and 2 described above, and therefore it is desired to solve it.

An object of the present invention is to provide a method of manufacturing a semiconductor package which can suppress warpage after polishing a sealing material using a sealing resin sheet.

As a result of intensive review, the present inventors have found that in the sealing body of the resin-sealed semiconductor wafer, the shrinkage force at the time of thermosetting of the sealing resin sheet remains, and the shrinking force is continuously applied to the polished body after grinding, which may be The warpage of the abrasive body is generated. Based on this knowledge, the present inventors further conducted an active review, and as a result, found that the above problems can be solved by the following configuration, and the present invention has been completed.

That is, the present invention is a method of manufacturing a semiconductor package, comprising: a sealing body forming step of forming a sealing body in which one or more semiconductor wafers are embedded in a sealing resin sheet; and a grinding step of grinding the sealing resin of the sealing body Slice The surface on the side opposite to the active surface of the semiconductor wafer is exposed to form a polishing body, and the minimum height difference between the surface of the sealing resin sheet and the exposed surface of the semiconductor wafer in the polishing body is 10 μm or more.

In the production method, the minimum height difference between the surface of the sealing resin sheet and the exposed surface of the semiconductor wafer in the polishing body is 10 μm or more, and the resin sheet is relatively polished with respect to the semiconductor wafer sealing resin sheet. Therefore, the area where the contracting force of the sealing resin sheet in the polishing body acts can be reduced, and the contraction force applied to the entire polishing body can be reduced to suppress the warpage of the polishing body. When the minimum height difference is less than 10 μm, the shrinkage of the region where the contraction force acts in the polishing body is insufficient, and the warpage of the polishing body may occur.

The sealing resin sheet after heat-hardening treatment at 150 ° C for 1 hour preferably has a Shore D hardness at 25 ° C of 20 or more and 60 or less. Moreover, the storage elastic modulus of the sealing resin sheet after the heat curing treatment at 150 ° C for 1 hour at 25 ° C is preferably 0.1 GPa or more and 3 GPa or less. According to the review by the present inventors, one of the main causes of the difference in the polishing surface of the polishing body is presumed to be the difference between the hardness of the sealing resin sheet (after the thermosetting treatment) and the hardness of the semiconductor wafer in the sealing body (hereinafter, simply referred to as "hardness difference"). . That is, it is estimated that the difference in hardness is large as the time difference is large, and the correlation between the hardness difference and the small difference is also small. In the manufacturing method, by setting the Shore D hardness or the storage elastic modulus within the above range, the hardness difference can be increased to increase the initial height difference in the polishing surface of the polishing body, and as a result, the result can be efficiently The generation of warpage of the abrasive body is suppressed.

In the foregoing sealing body forming step, the flip chip connection can be The semiconductor wafer to be connected to the semiconductor wafer may be embedded in the sealing resin sheet to form the sealing body, or the semiconductor wafer fixed to the temporary fixing material may be embedded in the sealing resin sheet to form the sealing body. The former is suitable for the process of arranging a semiconductor wafer on a wafer to fabricate a wafer-on-a-chip of a semiconductor device, and the latter is suitable for a fan-out wafer level package. Regardless of the form in which the sealing body is formed, the warpage of the polishing body can be suppressed, and the variability in the manufacturing process of the semiconductor package can be increased.

The manufacturing method may further include a back grinding step of polishing the active surface side surface of the semiconductor wafer of the polishing body after the polishing step.

The manufacturing method may further include a rewiring forming step of forming a rewiring on the active surface side surface of the semiconductor wafer of the polishing body after the polishing step or after the back grinding step.

In the manufacturing method, a plurality of the semiconductor wafers are used, and a dicing step may be further included. After the rewiring forming step, the polishing body is cut in units of a desired semiconductor wafer.

2‧‧‧ Temporary fixtures

2a‧‧‧Hot-expandable adhesive layer

2b, 11a‧‧‧Support

11,21‧‧‧ sealing resin sheet

11S, 21S‧‧‧ Surface of sealing resin sheet

12a‧‧‧through electrode

12A, 12B‧‧‧ semiconductor wafer

13,23‧‧‧Semiconductor wafer

13a‧‧‧protruding electrode

13S, 23S‧‧‧ exposed face

14‧‧‧Bottom filler

15,25‧‧‧ Sealing body

16,26‧‧‧Abras

16A, 16B, 16C‧‧‧ grinding body

17,27‧‧‧Bumps

18,28‧‧‧ semiconductor package

19,29‧‧‧Rewiring

A, A1, A2‧‧‧ active surface

B1, B2‧‧‧

G1, G2‧‧‧ grinding surface

Simple description of the schema

Fig. 1A is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 1B is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 1C is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 1D is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 1E is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 1F is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 1G is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing a sealing resin sheet according to an embodiment of the present invention.

Fig. 3A is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Fig. 3B is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Fig. 3C is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Fig. 3D is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Fig. 3E is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Fig. 3F is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Fig. 3G is a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention.

Figure 4 is a plan view schematically showing the steps of measuring the minimum height difference of the abrasive surface of the abrasive body.

Form for implementing the invention

Embodiments of a method of manufacturing a semiconductor package of the present invention will be described below with reference to the drawings. However, in some or all of the drawings, the parts that are not required to be described are omitted, and for the sake of easy explanation, there are enlarged or reduced portions to be illustrated. The terms showing the positional relationship of the top and bottom are used for ease of explanation, and the intention of the structure of the present invention is not limited at all.

<First embodiment>

[Manufacturing Method of Semiconductor Package]

A method of manufacturing the semiconductor package of the present embodiment using a sealing resin sheet will be described with reference to Figs. 1A to 1G. 1A to 1G are each a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to an embodiment of the present invention. In the first embodiment, a semiconductor package mounted on a semiconductor wafer is resin-sealed by sealing a resin sheet to form a semiconductor package. The method of manufacturing a semiconductor package of the first embodiment is suitable for a wafer-on-chip (COW) program.

(wafer-mounted wafer preparation step)

In the wafer-mounted wafer preparation step, a semiconductor wafer 12A in which a plurality of semiconductor wafers 13 are flip-chip bonded is prepared (see FIG. 1A). The semiconductor wafer 13 can be formed by dicing a semiconductor wafer on which a predetermined circuit has been formed by a conventional method. In order to mount the semiconductor wafer 13 on the semiconductor wafer 12A, a conventional device such as a flip chip bonding machine can be used. In this embodiment, The active surface A1 of the semiconductor wafer 13 on which the bump electrodes 13a are formed is flip-chip bonded to the semiconductor wafer 12A. The semiconductor wafer 13 and the semiconductor wafer 12A are electrically connected to each other through the bump electrode 13a formed on the bump of the semiconductor wafer 13 or the through electrode 12a provided in the semiconductor wafer 12A. As the through electrode 12a, an electrode in the form of TSV (Through Silicon Via) can be suitably used.

Further, an underfill material 14 is interposed between the semiconductor wafer 13 and the semiconductor wafer 12A, and the underfill material 14 serves to alleviate the difference in thermal expansion coefficients of the two, in particular, to prevent cracks in the connection portion from occurring. The underfill 14 can be used by conventional practitioners. The bottom filler 14 can be disposed after the semiconductor wafer 13 is mounted on the semiconductor wafer 12A, and the liquid underfill 14 is injected therebetween, and the semiconductor wafer having the sheet-shaped underfill 14 can also be prepared. After the semiconductor wafer 12A or 13A, the semiconductor wafer 13 and the semiconductor wafer 12A are connected.

(sealing step)

In the sealing step, the sealing resin sheet 11 is laminated on the semiconductor wafer 12A to embed the semiconductor wafer 13, and the semiconductor wafer 13 is sealed by the above-mentioned sealing resin sheet resin (refer to FIG. 1B). The sealing resin sheet 11 has a function as a function of protecting the semiconductor wafer 13 and its accompanying elements from the external environment.

The method of laminating the sealing resin sheet 11 is not particularly limited, and for example, a molten mixture of a resin composition for forming a sealing resin sheet is extrusion-molded, and the extruded product is placed on the semiconductor wafer 12A and pressed. a method of forming a sealing resin sheet 11 in batches, and in a release treatment The resin composition for sealing the resin sheet 11 is applied on the sheet, and the method of drying the coating film to form the sealing resin sheet 11 and then transferring the sealing resin sheet 11 onto the semiconductor wafer 12A is applied.

In the present embodiment, by using the sealing resin sheet 11, it is possible to embed the semiconductor wafer 13 by adhering to the semiconductor wafer 12A by coating the semiconductor wafer 13, thereby improving the production efficiency of the semiconductor package. . At this time, the sealing resin sheet 11 can be laminated on the semiconductor wafer 12A by a conventional method such as hot pressing and lamination. As a hot pressing condition, the temperature system is, for example, 40 to 120 ° C, and preferably 50 to 100 ° C, a pressure system, for example, 50 to 2500 kPa, and preferably 100 to 2000 kPa, time, for example, 0.3 to 10 minutes, and It should be 0.5 to 5 minutes. When it is considered to improve the adhesion and followability of the sealing resin sheet 11 to the semiconductor wafer 13 and the semiconductor wafer 12A, it is preferable to carry out pressing under reduced pressure conditions (for example, 10 to 2000 Pa).

(sealing body forming step)

In the sealing body forming step, after the sealing resin sheet is thermally cured, the sealing body 15 in which the semiconductor wafer 13 is embedded in the sealing resin sheet 11 is formed (see FIG. 1B). The heat hardening treatment condition of the sealing resin sheet is preferably a heating temperature of 100 ° C to 200 ° C, and more preferably 120 ° C to 180 ° C, and the heating time is preferably between 10 minutes and 180 minutes, and between 30 minutes and 120 minutes. Better, it can also be pressurized as needed. When pressurizing, it is preferred to use 0.1 MPa to 10 MPa, and more preferably 0.5 MPa to 5 MPa.

(grinding step)

In the polishing step, the sealing resin sheet 11 of the polishing sealing body 15 is exposed to the surface on the side opposite to the exposed surface 13S of the active surface A of the semiconductor wafer 13. The polishing body 16A is formed (see FIG. 1C). At the time of polishing, the semiconductor wafer 13 may be polished together with the sealing resin sheet 11 as shown in Fig. 1C, or only the sealing resin sheet 11 may be polished. Grinding can be carried out using a conventional polishing apparatus. A step of forming the polishing body 16A by rotating the polishing tool such as a diamond turning tool to the surface of the sealing body by polishing the sealing body 15 can be suitably employed.

The minimum height difference between the surface 11S of the sealing resin sheet and the exposed surface 13S of the semiconductor wafer in the polishing body 16A is 10 μm or more, and preferably 20 μm or more. By setting the minimum height difference of the polishing surface G1 within the above range, the region where the contracting force of the sealing resin sheet 11 in the polishing bodies 16A, 16B, and 16C (refer to FIGS. 1C to 1F) acts can be reduced, and the polishing body can be suppressed. Warp. Further, the upper limit of the minimum height difference is preferably 50 μm or less from the viewpoint of the mechanical strength of the polishing body, and more preferably 40 μm or less.

(back grinding step)

In the back grinding step, the surface opposite to the polishing surface G1 of the polishing body 16A (that is, the back surface B1) is polished (see FIG. 1D). Thereby, the exposed surface of the semiconductor wafer 12A can be polished to obtain a thinned semiconductor wafer 12B. The thickness of the ground semiconductor wafer 12B may vary depending on the specifications of the package of the object, and is, for example, preferably 25 to 200 μm, and more preferably 50 to 100 μm. Grinding can be carried out using a conventional polishing apparatus. For the fixing of the polishing body 16A, a conventional back grinding tape can be used.

Further, when a thin semiconductor wafer 12A having a desired thickness is used as a wafer for wafer mounting, the back grinding step can be omitted. At this time, each step may be performed after the support material of the reinforcing semiconductor wafer 12A is pasted on the semiconductor wafer 12A. The grinding body 16B is due to the above minimum height difference The shrinkage force applied to the polishing body 16B is reduced to 10 μm or more, so that the warpage of the polishing body can be suppressed even after the support member is peeled off.

(rewiring forming step)

In the present embodiment, it is preferable to further include a rewiring forming step of forming the rewiring 19 on the surface B1 on the active surface A1 side of the semiconductor wafer 13 of the polishing body 16B (see FIG. 1E). In the rewiring forming step, after the thinned semiconductor wafer 12B is formed by back surface polishing, the rewiring 19 connected to the through electrode 12a of the semiconductor wafer 12B is formed on the polishing body 16B.

As a method of forming the rewiring, for example, a metal sheet layer is formed on the exposed semiconductor wafer 12B by a conventional method such as a vacuum film forming method, and a conventional method such as a semi-additive process (SAP) is known. In this way, rewiring 19 can be formed.

Then, an insulating layer such as polyimide or PBO can be formed on the rewiring 19 and the polishing body 16B.

(bump forming step)

Next, bump processing for forming the bumps 17 on the formed rewiring 19 can be performed (refer to FIG. 1F). The bump processing can be performed by a conventional method such as solder balls and solder plating. The material of the bump is not particularly limited, and examples thereof include a tin-lead metal material, a tin-silver metal material, a tin-silver-copper metal material, a tin-zinc metal material, and a tin-zinc-antimony system. Solder (alloy) such as metal, gold-based metal, and copper-based metal.

(wafer back protection step)

After the bumps 17 are formed, in order to protect the exposed surface 13S of the semiconductor wafer 13, the polished surface G1 (see FIG. 1C) of the polishing body 16A may be resin-sealed again. dense The sealing method is not particularly limited, and a liquid or film-like sealing resin is applied or adhered to the polishing surface G1 to dry and harden it. Again, this step can be carried out at any stage prior to the cutting step after the grinding step.

(cutting step)

Then, the polishing body 16C formed by the bumps formed of the elements such as the sealing resin sheet 11, the semiconductor wafer 12B, and the semiconductor wafer 13 may be cut (see FIG. 1G). Thereby, the semiconductor package 18 of the intended semiconductor wafer 13 unit can be obtained. Although the dicing is performed corresponding to one semiconductor wafer in FIG. 1G, two or more semiconductor wafers may be diced in one unit. Usually, the cutting is performed by fixing the above-mentioned polishing body 16 by a conventionally used cutting piece. The alignment of the cut-offs can also be performed by image recognition using direct or indirect illumination.

In this step, for example, a cutting method or the like for performing full cutting until cutting into a dicing sheet can be employed. The cutting device used in this step is not particularly limited, and conventional ones can be used.

Further, when the subsequent cutting step is performed to expand the polishing body, the expansion can be carried out using a conventional expansion device. The expansion device has a circular outer ring that can be pressed down to the lower side by cutting, and an inner ring that is smaller in diameter than the outer ring and supports the cutting piece. By this expansion step, adjacent semiconductor packages 18 can be prevented from being damaged by contact with each other.

(substrate mounting step)

A substrate mounting step of mounting the semiconductor package 18 obtained by the above on another substrate (not shown) may be performed as needed. The semiconductor package 18 is mounted on the substrate, and a conventional device such as a flip chip bonding machine and a splicing machine can be used. Set.

[sealing resin sheet]

The sealing resin sheet of this embodiment will be described with reference to Fig. 2 . Fig. 2 is a cross-sectional view schematically showing a sealing resin sheet according to an embodiment of the present invention. The sealing resin sheet 11 is typically provided in a state of being laminated on a support 11a such as a polyethylene terephthalate (PET) film. Further, in the support 11a, in order to easily peel off the sealing resin sheet 11, a release treatment can be performed.

In addition, the Shore D hardness of the sealing resin sheet 11 after the heat hardening treatment at 150 ° C for 1 hour at 25 ° C is preferably 20 or more and 60 or less, and more preferably 30 or more and 50 or less. In addition, the storage elastic modulus of the sealing resin sheet 11 after heat-hardening treatment at 150 ° C for 1 hour at 25 ° C is preferably 0.1 GPa or more and 3 GPa or less, more preferably 0.5 Pa or more and 2 GPa or less. By setting the Shore D hardness or the storage elastic modulus of the sealing resin sheet 11 after the heat hardening treatment within the above range, the hardness difference can be increased, so that the above-described minimum height difference can be increased. As a result, the contraction force in the abrasive body 16A can be reduced to suppress warpage.

(Resin composition forming the sealing resin sheet)

The resin composition forming the sealing resin sheet is preferably one having the above characteristics and can be used for the resin sealing of the semiconductor wafer, and is not particularly limited, but preferably contains the following epoxy of the A component to the E component. The resin composition is exemplified. Further, the C component may or may not be added as needed.

Component A: Epoxy

B component: phenolic resin

Component C: Elastomer

D component: inorganic filler

Component E: Hardening accelerator

(component A)

The epoxy resin (component A) is not particularly limited. For example, a triphenylmethane type epoxy resin, a cresol novolac type epoxy resin, a biphenyl type epoxy resin, a denatured bisphenol A type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type ring can be used. Various epoxy resins such as an oxygen resin, a denatured bisphenol F type epoxy resin, a dicyclopentadiene type epoxy resin, a phenol novolak type epoxy resin, and a phenoxy resin. These epoxy resins may be used singly or in combination of two or more.

From the viewpoint of ensuring the toughness of the epoxy resin after hardening and the reactivity of the epoxy resin, it is preferably an epoxy equivalent of 150 to 250, a softening point or a melting point of 50 to 130 ° C at a normal temperature, wherein reliability is achieved. From the viewpoint of view, it is preferably a triphenylmethane type epoxy resin, a cresol novolak type epoxy resin, or a biphenyl type epoxy resin.

Further, from the viewpoint of low stress, it is preferably a denatured bisphenol A type epoxy resin having a soft skeleton such as an acetal group or a polyoxyalkylene group, and a denatured bisphenol A type epoxy resin having an acetal group. It is liquid and has good handleability, so it can be used particularly suitably.

The content of the epoxy resin (component A) is preferably set in the range of 1 to 10% by weight based on the entire epoxy resin composition.

(B component)

The phenol resin (component B) is not particularly limited as long as it undergoes a curing reaction with the epoxy resin (component A). For example, a phenol novolak resin, a phenol aralkyl resin, a biphenyl aralkyl resin, a dicyclopentadiene type phenol resin, a cresol novolak resin, a resol resin, or the like can be used. These phenol resins can be used alone. Two or more types may be used in combination.

From the viewpoint of reactivity with the epoxy resin (component A), the phenol resin preferably has a hydroxyl group equivalent of 70 to 250 and a softening point of 50 to 110 ° C, and may be suitably used from the viewpoint of hardening reactivity. Such as phenol aralkyl resin or biphenyl aralkyl resin low hygroscopicity.

The blending ratio of the epoxy resin (component A) and the phenol resin (component B) is 1 equivalent of the epoxy group in the epoxy resin (component A) from the viewpoint of curing reactivity, and the phenol resin (component B) The total of the hydroxyl groups in the mixture is preferably 0.7 to 1.5 equivalents, more preferably 0.9 to 1.2 equivalents.

The total content of the epoxy resin and the phenol resin in the sealing resin sheet 11 is preferably 2.5% by weight or more, more preferably 3.0% by weight or more. When it is 2.5% by weight or more, the adhesion to the semiconductor wafer 13, the semiconductor wafer 12A, and the like can be favorably obtained. The total content of the epoxy resin and the phenol resin in the sealing resin sheet 11 is preferably 20% by weight or less, more preferably 10% by weight or less. When it is 20% by weight or less, hygroscopicity can be reduced.

(C component)

The elastomer (component C) used together with the epoxy resin (component A) and the phenol resin (component B) imparts flexibility necessary for sealing the semiconductor wafer with the sealing resin sheet by the resin composition, and has such an effect. There are no special restrictions. For example, various acrylic copolymers such as polyacrylate, styrene acrylic copolymer, butadiene rubber, styrene-butadiene rubber (SBR), ethylene vinyl acetate copolymer (EVA), and isoprene can be used. A rubbery polymer such as a diene rubber or an acrylonitrile rubber. Among them, it is easy to disperse into an epoxy resin (component A) and has high reactivity with an epoxy resin (component A). From the viewpoint of heat resistance or strength of the highly obtained sealing resin sheet, an acrylic copolymer is preferably used. These may be used alone or in combination of two or more.

Further, the acrylic copolymer can be synthesized, for example, by radical polymerization of an acrylic monomer mixture having a predetermined mixing ratio by a usual method. As the method of the radical polymerization, a solution polymerization method using an organic solvent as a solvent and a suspension polymerization method in which a raw material monomer is dispersed while being dispersed in water can be used. The polymerization initiator used at this time can be used, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2' -Azobis-4-methoxy-2,4-dimethylvaleronitrile, other azo or diazo polymerization initiators, peroxides such as benzamidine peroxide and butanone peroxide It is a polymerization initiator or the like. Further, in the case of suspension polymerization, for example, a dispersant such as polypropylene decylamine or polyvinyl alcohol is preferably added.

The content of the elastomer (component C) is 15 to 30% by weight based on the entire epoxy resin composition. When the content of the elastomer (component C) is less than 15% by weight, it is difficult to obtain the flexibility and flexibility of the sealing resin sheet 11, and it is also difficult to further suppress the resin sealing of the warpage of the sealing resin sheet. On the other hand, when the content is more than 30% by weight, the melt viscosity of the sealing resin sheet 11 is increased, and the embedding property of the semiconductor wafer 13 is lowered, and the strength and heat resistance of the cured body of the sealing resin sheet 11 tend to be lowered.

Further, the weight ratio of the elastomer (component C) to the epoxy resin (component A) (weight of the component C / weight of the component A) is preferably set in the range of 3 to 4.7. This is because when the weight ratio is less than 3, it is difficult to control the fluidity of the sealing resin sheet 11, and when it exceeds 4.7, the adhesion of the sealing resin sheet 11 to the semiconductor wafer 13 tends to deteriorate.

(D component)

The inorganic filler (component D) is not particularly limited, and various conventional fillers can be used, and examples thereof include quartz glass, talc, cerium oxide (melted cerium oxide or crystalline cerium oxide), and alumina. , aluminum nitride, tantalum nitride, boron nitride powder. These may be used alone or in combination of two or more.

Among them, the internal stress is lowered by reducing the coefficient of thermal linear expansion of the hardened body of the epoxy resin composition, and as a result, it is possible to suppress the warpage of the sealing resin sheet 11 after sealing the semiconductor wafer, and it is preferable to use cerium oxide powder or cerium oxide. In the powder, molten cerium oxide powder is preferably used. The molten cerium oxide powder is exemplified by a spherical molten cerium oxide powder and a crushed molten cerium oxide powder. However, from the viewpoint of so-called fluidity, it is particularly preferable to use a spherical molten cerium oxide powder. Among them, it is preferred to use a range of an average particle diameter of 0.1 to 30 μm, and it is particularly preferable to use a range of 1 to 20 μm.

Further, the average particle diameter can be derived by using a sample arbitrarily extracted by a parent group and measuring by using a laser diffraction scattering type particle size distribution measuring device.

The content of the inorganic filler (component D) is preferably 70 to 95% by weight of the entire epoxy resin composition, more preferably 75 to 92% by weight, and still more preferably 80 to 90% by weight. When the content of the inorganic filler (component D) is less than 50% by weight, the linear expansion coefficient of the cured body of the epoxy resin composition increases, so that the warpage of the sealing resin sheet 11 tends to be large. On the other hand, when the content is more than 90% by weight, the flexibility or fluidity of the sealing resin sheet 11 is deteriorated, so that the adhesion to the semiconductor wafer tends to be lowered.

(E component)

The hardening accelerator (component E) is not particularly limited as long as it can be cured by the epoxy resin and the phenol resin, but triphenylphosphine or tetraphenylphosphonium tetraborate can be suitably used from the viewpoint of curability and preservability. An organic phosphorus compound such as an ester or an imidazole compound. These hardening accelerators may be used singly or in combination with other hardening accelerators.

The content of the curing accelerator (component E) is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the total of the epoxy resin (component A) and the phenol resin (component B).

(other ingredients)

Further, in the epoxy resin composition, a flame retardant component may be added in addition to the components A to E. As the flame retardant component, for example, various metal hydroxides such as aluminum hydroxide, magnesium hydroxide, iron hydroxide, calcium hydroxide, tin hydroxide, and a composite metal hydroxide can be used.

The average particle diameter of the metal hydroxide is preferably from 1 to 10 μm, more preferably from 2 to 5 μm, from the viewpoint of ensuring proper fluidity when heating the epoxy resin composition. When the average particle diameter of the metal hydroxide is less than 1 μm, it is difficult to uniformly disperse the epoxy resin composition, and the epoxy resin composition tends to fail to obtain sufficient fluidity when heated. In addition, when the average particle diameter exceeds 10 μm, the surface area of the metal hydroxide (E component) is gradually increased, so that the flame retarding effect tends to be lowered.

Further, as the flame retardant component, in addition to the above metal hydroxide, an azophosphorus compound can be used. The phosphine compound can be commercially available, for example, from SPR-100, SA-100, SP-100 (above, Otsuka Chemical Co., Ltd.), FP-100, FP-110 (above, Fushimi Pharmaceutical Co., Ltd.). Product acquisition.

From the viewpoint of exhibiting a flame retarding effect even in a small amount, it is preferably an even phosphorus nitrogen compound represented by the formula (1) or the formula (2), and the content of the phosphorus element contained in the orthophosphorus nitrogen compound is preferably 12 More than weight%.

(In the formula (1), n is an integer of 3 to 25, and R ¹ and R ^{2 are the} same or different, and have a group selected from the group consisting of an alkoxy group, a phenoxy group, an amine group, a hydroxyl group, and an allyl group. a monovalent organic group of a functional group of the group.)

(In the formula (2), n and m are each independently an integer of from 3 to 25. R ³ and R ^{5 are the} same or different and are selected from alkoxy groups, phenoxy groups, amine groups, hydroxyl groups, and a monovalent organic group of a functional group of a group consisting of allyl groups. R ⁴ is a divalent group having a functional group selected from the group consisting of an alkoxy group, a phenoxy group, an amine group, a hydroxyl group, and an allyl group. Organic base.)

Further, from the viewpoint of so-called stability and suppression of pore formation, a cyclic azo-phosphorus oligomer represented by the formula (3) is preferably used.

(In the formula (3), n is an integer of from 3 to 25, and R ⁶ and R ^{7 are the} same or different and are hydrogen, a hydroxyl group, an alkyl group, an alkoxy group or a glycidyl group.)

The cyclic azo-phosphorus oligomer represented by the formula (3) can be obtained from commercially available products such as FP-100 and FP-110 (above, Fushimi Pharmaceutical Co., Ltd.).

The content of the azo-phosphorus compound is preferably an epoxy resin (component A), a phenol resin (component B), an elastomer (component D), a hardening accelerator (component E), and an arsenic nitrogen contained in the epoxy resin composition. The organic component of the compound (other components) is 10 to 30% by weight as a whole. In other words, when the content of the azo-phosphorus compound is less than 10% by weight based on the entire organic component, the flame retardancy of the sealing resin sheet 11 is lowered, and the adherend (that is, the semiconductor wafer on which the semiconductor wafer is mounted in the embodiment) is affixed to the semiconductor wafer. The bump followability is lowered, and there is a tendency to generate voids. When the content exceeds 30% by weight of the entire organic component, cracks are likely to occur on the surface of the sealing resin sheet 11, and workability such as alignment of the adherend is less likely to occur.

Further, by using the above metal hydroxide and the azo-phosphorus compound, a sealing tree which ensures the flexibility required for the sheet sealing and which has excellent flame retardancy can be obtained. Fat sheet 11. By using both, it is possible to obtain sufficient flame retardancy when only a metal hydroxide is used, and sufficient flexibility when only a phosphorus-nitrogen compound is used.

Among the flame retardants, it is desirable to use an organic flame retardant in terms of the deformability of the sealing resin sheet during sealing molding of the resin, the unevenness of the adherend, and the adhesion to the semiconductor wafer or the semiconductor wafer. An azo-phosphorus flame retardant is used.

Further, in addition to the above respective components, the epoxy resin composition may be appropriately blended with other additives such as a pigment such as carbon black.

(Preparation method of sealing resin sheet)

The preparation method of the sealing resin sheet will be described below. First, an epoxy resin composition is prepared by mixing the above components. The mixing method is not particularly limited as long as it can uniformly disperse and mix the respective components. Then, for example, a varnish formed by dissolving or dispersing each component in an organic solvent or the like is applied to form a sheet. Alternatively, the blend may be prepared by directly blending the blended components with a kneading machine or the like, and the thus obtained blend is extruded to form a sheet.

The specific preparation step of using the varnish is carried out by appropriately mixing the above components A to E and other additives as needed according to a usual method, and uniformly dissolving or dispersing them in an organic solvent to prepare a varnish. Next, the varnish is applied onto a support such as polyester and dried to obtain a sealing resin sheet 11. Further, in order to protect the surface of the sealing resin sheet, a release sheet such as a polyester film may be adhered as needed. The release sheet is peeled off at the time of sealing.

The above organic solvent is not particularly limited, and various conventional organic solvents such as methyl ethyl ketone, acetone, cyclohexanone, diethyl ketone, and methyl can be used. Benzene, ethyl acetate, etc. These may be used alone or in combination of two or more. Further, in general, it is preferred to use an organic solvent so that the solid concentration of the varnish is in the range of 30 to 60% by weight.

The thickness of the sheet after drying of the organic solvent is not particularly limited, but is usually preferably 5 to 100 μm, more preferably 20 to 70 μm from the viewpoint of uniformity of thickness and amount of residual solvent.

On the other hand, when blending is used, the above-mentioned components A to E and other additives as needed are mixed by a conventional method such as a mixer, and then the blend is prepared by melt blending. The method of melt blending is not particularly limited, but a method of melt blending by a conventional blender such as a mixing roll, a press type kneader, or an extruder can be exemplified. The blending conditions are not particularly limited as long as the temperature is higher than the softening point of each of the above components, for example, 30 to 150 ° C, and when considering the thermosetting property of the epoxy resin, it is preferably 40 to 140 ° C, and more preferably 60 to 120 ° C. Preferably, the time is, for example, 1 to 30 minutes, and preferably 5 to 15 minutes. Thereby, the blend can be prepared.

The obtained blend is formed by extrusion molding, whereby the sealing resin sheet 11 can be obtained. Specifically, the sealing resin sheet 11 can be formed by performing extrusion molding without cooling the melt-blended blend and maintaining the high temperature state. The extrusion method is not particularly limited, and examples thereof include a T-die extrusion method, a roll method, a roll blending method, a co-extrusion method, and a calender molding method. The extrusion temperature is not particularly limited as long as it is at least the softening point of each of the above components, but in consideration of thermosetting property and formability of the epoxy resin, for example, 40 to 150 ° C, and preferably 50 to 140 ° C, and 70 to 70 120 ° C is even better. By the above, the sealing resin sheet 11 can be formed.

The sealing resin sheet thus obtained can also be laminated to a desired thickness as needed. In other words, the sealing resin sheet can be used in a single layer structure, or can be used as a laminate in which a plurality of layers of two or more layers are laminated.

<Second embodiment>

Hereinafter, a second embodiment of an embodiment of the present invention will be described. 3A to 3G are each a cross-sectional view schematically showing a step of a method of manufacturing a semiconductor package according to another embodiment of the present invention. In the first embodiment, the semiconductor wafer is flip-chip bonded to the semiconductor wafer by the sealing resin sheet resin. However, in the second embodiment, the semiconductor wafer is temporarily fixed on the temporary fixing material instead of the semiconductor wafer. The sealing resin is carried out in a state. This second embodiment is suitable for manufacturing a semiconductor package called a so-called Fan-out wafer level package (WLP).

[temporary fixing material preparation steps]

In the temporary fixing material preparation step, the temporary fixing member 2 in which the heat-expandable pressure-sensitive adhesive layer 2a is laminated on the support 2b is prepared (see FIG. 3A). Further, a radiation curable adhesive layer may be used instead of the heat-expandable adhesive layer. In the present embodiment, the temporary fixing member 2 having the heat-expandable pressure-sensitive adhesive layer will be described.

(heat-expandable adhesive layer)

The heat-expandable adhesive layer 2a can be formed by an adhesive composition containing a polymer component and a foaming agent. As the polymer component (particularly, the base polymer), an acrylic polymer (sometimes referred to as "acrylic polymer A") can be suitably used. The acrylic polymer A can be exemplified by using a (meth) acrylate as a main monomer. The aforementioned (meth) acrylate may, for example, be an alkyl (meth) acrylate. Esters (eg, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, secondary butyl ester, tertiary butyl ester, amyl ester, isoamyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, decyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, stearyl ester, etc. The alkyl group has 1 to 30 carbon atoms, particularly a linear or branched alkyl ester having 4 to 18 carbon atoms, and a cycloalkyl (meth)acrylate (for example, cyclopentyl ester or cyclohexyl ester). . These (meth)acrylates may be used alone or in combination of two or more.

Further, the acrylic polymer A is intended to be modified by cohesive force, heat resistance and crosslinkability, and may further contain other monomer components which are copolymerizable with the acrylic polymer A as needed. The monomer component may, for example, be a carboxyl group-containing monomer such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid or carboxyethyl acrylate; An acid anhydride group-containing monomer such as an acid anhydride or an isonic anhydride; a hydroxyl group-containing monomer such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybutyl (meth)acrylate; (methyl) Acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide or N-hydroxymethyl(meth)acrylamide, N-methylolpropane (N-substituted or unsubstituted) guanamine monomer such as (meth) acrylamide; vinyl ester monomer such as vinyl acetate or vinyl propionate; styrene, α-methyl styrene, etc. Styrene monomer; cyanoacrylate monomer such as acrylonitrile or methacrylonitrile; epoxy group-containing acrylic monomer such as (meth)acrylic acid propylene oxide; ethylene, propylene, isoprene An olefin or a diene monomer such as butadiene or isobutylene; an amine ethyl (meth)acrylate, N,N-dimethylamine ethyl (meth)acrylate, or a tertiary butylamine (meth)acrylate Ethyl acetate, etc. a substituted or unsubstituted) amino group; a (meth)acrylic alkoxyalkyl monomer such as methoxyethyl (meth)acrylate or ethoxyethyl acrylate; N-vinylpyrrolidone; N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylperidazole N-vinylpyrene a monomer having a nitrogen atom-containing ring such as N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylformin, N-ethylene caprolactam or the like; N-vinylcarboxylic acid guanamine a sulfonic acid group-containing monomer such as styrenesulfonic acid, allylsulfonic acid, (meth)acrylic acid decylpropanesulfonic acid or sulfonic acid propyl (meth)acrylate; (meth)acrylic acid-2-hydroxyl a phosphoric acid group-containing monomer such as ethylene propylene phthalate phosphate; N-cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, a maleimide monomer such as N-phenyl maleimide or the like; N-methyl Ikonide, N-ethyl Ikonide, N-butyl Itacon Yikang, N-octylkonkineimine, N-2-ethylhexylkamponium imine, N-cyclohexylkkonium imine, N-Lauryl Iccomide, etc.醯imino monomer; N-(methyl) propylene oxymethylene succinimide, N-(methyl) propylene 醯-6-oxyhexamethylene succinimide, N-(methyl) propylene oxime Amber quinone imine monomer such as 8-methoxy-octamethyl succinimide; polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, etc. a diol-based acrylate monomer; a monomer having an oxygen atom-containing hetero ring such as tetrahydrofurfuryl (meth) acrylate; and a fluorine atom-containing acrylate monomer such as a fluorinated (meth) acrylate; a ruthenium atom-containing acrylate monomer such as polyoxymethylene (meth) acrylate; hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol Di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol III (Meth) acrylate, dipentaerythritol hexa(meth) acrylate, epoxy (meth) acrylate, polyester acrylate, urethane acrylate, divinyl benzene, butyl bis (A) A polyfunctional monomer such as an acrylate or hexyl di(meth)acrylate.

The acrylic polymer A is obtained by polymerizing a single monomer or a mixture of two or more kinds of monomers. The polymerization can be carried out by any means such as solution polymerization (for example, radical polymerization, anionic polymerization, cationic polymerization, etc.), emulsion polymerization, bulk polymerization, suspension polymerization, photopolymerization (for example, ultraviolet (UV) polymerization, and the like.

The weight average molecular weight of the acrylic polymer A is not particularly limited, and is preferably from about 350,000 to 1,000,000, and more preferably from about 450,000 to 800,000.

Further, in order to adjust the adhesive force, an external crosslinking agent can be suitably used as the heat-expandable adhesive. A specific method of the method of external crosslinking may be exemplified by a method of adding a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, a hydrazine propane compound or a melamine crosslinking agent. When an external crosslinking agent is used, the amount thereof can be determined by the balance with the base polymer to be crosslinked, and further, depending on the use as the adhesive. The amount of the external crosslinking agent to be used is generally 20 parts by weight or less (preferably 0.1 parts by weight to 10 parts by weight) based on 100 parts by weight of the aforementioned base polymer.

The heat-expandable pressure-sensitive adhesive layer 2a contains a foaming agent for imparting thermal expansion properties as described above. Therefore, in a state in which the polishing body 26 including the semiconductor wafer 23 is polished is formed on the heat-expandable pressure-sensitive adhesive layer 2a of the temporary fixing member 2 (see FIG. 3C), the temporary fixing member 2 is at least partially heated at any time to be contained. The foaming agent of a portion of the heated heat-expandable adhesive layer 2a is foamed and/or expanded, whereby the heat-expandable adhesive layer 2a is at least partially The expansion, by the expansion of at least a portion of the heat-expandable adhesive layer 2a, the adhesive surface corresponding to the expanded portion (the interface with the polishing body 26) is deformed into a concavo-convex shape, and the thermally expandable adhesive layer 2a and the abrasive body Since the area of the joint of 26 is reduced, the adhesion between the two is reduced, and the abrasive body 26 can be peeled off by the temporary fixing member 2 (see Fig. 3D).

(foaming agent)

The foaming agent used in the heat-expandable pressure-sensitive adhesive layer 2a is not particularly limited and may be appropriately selected from conventional foaming agents. The foaming agents may be used singly or in combination of two or more. As the foaming agent, heat-expandable microspheres can be suitably used.

(heat-expandable microspheres)

The heat-expandable microspheres are not particularly limited, and can be appropriately selected from conventional heat-expandable microspheres (all kinds of inorganic heat-expandable microspheres, and organic heat-expandable microspheres). The heat-expandable microspheres can suitably use a microencapsulated foaming agent from the viewpoint of easy mixing operation. The heat-expandable microspheres may be exemplified by a microsphere or the like in which a substance which can be easily vaporized and expanded by heating, such as isobutane, propane or pentane, is enclosed in an elastic shell. Most of the above-mentioned shells are formed by a thermally fusible substance and a substance which is destroyed by thermal expansion. Examples of the material for forming the shell include a vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyethylene, butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polyfluorene, and the like. .

The heat-expandable microspheres can be produced by a conventional method such as a coacervation method, an interfacial polymerization method, or the like. In addition, the heat-expandable microspheres can be used, for example, the product name "Matsumoto Microsphere" manufactured by Matsumoto Oil & Fats Co., Ltd. (for example, the product name "Matsumoto Microsphere" F30", trade name "Matsumoto Microsphere F301D", trade name "Matsumoto Microsphere F50D", trade name "Matsumoto Microsphere F501D", trade name "Matsumoto Microsphere F80SD", trade name "Matsumoto Microsphere F80VSD", etc., and manufactured by EXPANCEL A commercial item such as the product name "051DU", the product name "053DU", the product name "551DU", the product name "551-20DU", and the product name "551-80DU".

In addition, when the heat-expandable microspheres are used as the foaming agent, the particle diameter (average particle diameter) of the heat-expandable microspheres can be appropriately selected depending on the thickness of the heat-expandable pressure-sensitive adhesive layer or the like. The average particle diameter of the heat-expandable microspheres can be selected, for example, from 100 μm or less (preferably 80 μm or less, more preferably from 1 μm to 50 μm, particularly preferably from 1 μm to 30 μm). Further, the adjustment of the particle diameter of the thermally expandable microspheres may be carried out during the formation of the thermally expandable microspheres, or may be carried out by a method such as classification after the formation. The heat-expandable microspheres should have a uniform particle size.

(other blowing agents)

In the present embodiment, a foaming agent other than the heat-expandable microspheres may be used as the foaming agent. Such a foaming agent can be appropriately selected from various foaming agents such as various inorganic foaming agents and organic foaming agents. Representative examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium boron hydride, and various guanamines.

Further, representative examples of the organic foaming agent include water; chlorofluoroalkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile and azodimethylamine; An azo compound such as arsenazodicarboxylate; p-toluenesulfonate, diphenylsulfon-3,3'-disulfonium, 4,4'-oxybis(phenylsulfonate), allylicene a quinone compound such as (phenylsulfonate); a semicarbazone compound such as p-toluenesulfonate, 4,4'-oxybis(benzenesulfonate); Triazole compound such as porphyrin-1,2,3,4-thiatriazole; N,N'-dinitrosopentylenetetramine, N,N'-dimethyl-N,N'- nitros An N-nitroso compound such as p-benzoylamine.

In the present embodiment, the adhesive force of the heat-expandable pressure-sensitive adhesive layer can be efficiently and stably lowered by heat treatment, so that the volume expansion ratio is five times or more, particularly seven times or more, and particularly ten times or more. A foaming agent of suitable strength for rupture is desirable.

The blending amount of the foaming agent (heat-expandable microspheres, etc.) can be appropriately set depending on the expansion ratio of the heat-expandable pressure-sensitive adhesive layer and the decrease in adhesion force, but generally, the base polymer 100 is formed with respect to the heat-expandable pressure-sensitive adhesive layer. The parts by weight are, for example, 1 part by weight to 150 parts by weight (preferably 10 parts by weight to 130 parts by weight, more preferably 25 parts by weight to 100 parts by weight).

In the present embodiment, the foaming agent may suitably use a foaming initiation temperature (thermal expansion starting temperature) (T ₀ ) in the range of 80 ° C to 210 ° C, and preferably has a temperature of 90 ° C to 200 ° C (95 ° C to The foaming start temperature is preferably 200 ° C and 100 ° C to 170 ° C. When the foaming start temperature of the foaming agent is lower than 80 ° C, the foaming agent may be foamed by the heat of the sealing body or the polishing body at the time of production or use, and the handleability or productivity may be lowered. On the other hand, when the foaming start temperature of the foaming agent exceeds 210 ° C, the support of the temporary fixing material or the sealing resin may require excessive heat resistance, which is not preferable in terms of handleability, productivity, and cost. Further, the expanding starting temperature of the foaming agent (T ₀₎ corresponds to the foaming starting temperature (T ₀₎ thermally expandable adhesive layers.

Further, the method of foaming the foaming agent (that is, the method of thermally expanding the heat-expandable pressure-sensitive adhesive layer) can be suitably selected by a conventional heat-expansion method.

In the present embodiment, the thermal expansion adhesive layer is preferably in the form of a balance between the moderate adhesion force before the heat treatment and the reduction in the adhesion force after the heat treatment, in the form without the foaming agent. 23 ° C to 150 ° C is 5 × 10 ⁴ Pa to 1 × 10 ⁶ Pa, and more preferably 5 × 10 ⁴ Pa to 8 × 10 ⁵ Pa, and 5 × 10 ⁴ Pa to 5 × 10 ⁵ Pa is particularly suitable. When the modulus of elasticity (temperature: 23 ° C to 150 ° C) of the heat-expandable pressure-sensitive adhesive layer is less than 5 × 10 ⁴ Pa, the thermal expansion property is deteriorated, and the peeling property is lowered. Further, when the elastic modulus (temperature: 23 ° C to 150 ° C) of the heat-expandable pressure-sensitive adhesive layer is not larger than 1 × 10 ⁶ Pa, the initial adhesive property is deteriorated.

Further, the heat-expandable adhesive layer in the form of no foaming agent corresponds to an adhesive layer formed by an adhesive (without a foaming agent). Therefore, the modulus of elasticity in the form in which the heat-expandable adhesive layer does not contain a foaming agent can be measured using an adhesive (without a foaming agent). Further, the heat-expandable adhesive layer may be an adhesive containing a pressure-sensitive adhesive layer capable of forming an elastic modulus of 5 × 10 ⁴ Pa to 1 × 10 ⁶ Pa at 23 ° C to 150 ° C, and a heat-expandable adhesive of a foaming agent. form.

The elastic modulus of the heat-expandable adhesive layer in the form of no foaming agent is a heat-expandable adhesive layer in a form in which no foaming agent is added (that is, an adhesive layer formed of an adhesive containing no foaming agent) (sample), using the dynamic viscoelasticity measuring device "ARES" manufactured by Rheometric, and using the sample thickness: about 1.5 mm, Φ7.9 mm parallel plate fixture, by shear force Mode, measured at frequency: 1 Hz, heating rate: 5 ° C / min, strain: 0.1% (23 ° C), 0.3% (150 ° C), shear storage elastic modulus G' obtained at 23 ° C and 150 ° C Value.

The elastic modulus of the heat-expandable adhesive layer can be controlled by adjusting the type of the base polymer of the adhesive, a crosslinking agent, an additive, and the like.

The thickness of the heat-expandable pressure-sensitive adhesive layer is not particularly limited and may be appropriately selected by the reduction of the adhesion force, etc., for example, about 5 μm to 300 μm (preferably 20 μm to 150 μm). However, when a heat-expandable microsphere is used as the foaming agent, the thickness of the heat-expandable pressure-sensitive adhesive layer is preferably thicker than the maximum particle diameter of the thermally expandable microspheres contained. When the thickness of the heat-expandable pressure-sensitive adhesive layer is too small, the surface smoothness is impaired by the unevenness of the heat-expandable microspheres, and the adhesion before heating (unfoamed state) is lowered. Further, the degree of deformation of the heat-expandable pressure-sensitive adhesive layer due to the heat treatment is small, and the adhesion force is hard to be smoothly reduced. On the other hand, when the thickness of the heat-expandable pressure-sensitive adhesive layer is too thick, the heat-expandable pressure-sensitive adhesive layer is liable to cause aggregation failure after expansion or foaming by heat treatment, and a paste remains on the polishing body 26.

Further, the heat-expandable adhesive layer may be a single layer or a plurality of layers.

In the present embodiment, the heat-expandable pressure-sensitive adhesive layer may further contain various additives (for example, a colorant, a tackifier, a bulking agent, a filler, an adhesion-imparting agent, a plasticizer, an anti-aging agent, an antioxidant, and a surfactant). , cross-linking agent, etc.).

(support)

The support 2b is a thin plate-shaped member which becomes the strength mother of the temporary fixing material 2. The material of the support 2b can be appropriately selected in consideration of handleability and heat resistance. A metal material such as SUS, a plastic material such as polyimide, polyamidoximine, polybutyl ketone or polyether oxime, glass, ruthenium wafer or the like can be used. Among these, glass, tantalum wafer, and SUS plate are preferable from the viewpoints of heat resistance, strength, and possibility of recycling.

The thickness of the support 2b can be appropriately selected in consideration of the strength or handleability of the object, and is preferably from 100 to 5000 μm, more preferably from 300 to 2000 μm.

(Method of forming temporary fixing materials)

The temporary fixing material 2 is obtained by forming the heat-expandable pressure-sensitive adhesive layer 2a on the support 2b. The heat-expandable pressure-sensitive adhesive layer can be formed by, for example, a conventional method of forming a sheet-like layer by mixing an adhesive, a foaming agent (heat-expandable microspheres, etc.), and a solvent and other additives as needed. Specifically, for example, a heat-expandable pressure-sensitive adhesive layer can be formed by coating a mixture containing an adhesive, a foaming agent (heat-expandable microspheres, etc.), and a solvent and other additives as needed. The method of the support 2b is a method of applying the above mixture to a suitable separator (release paper or the like) to form a heat-expandable pressure-sensitive adhesive layer, and transferring (transferring) the same to the support 2b.

(The thermal expansion method of the heat-expandable adhesive layer)

In the present embodiment, the heat-expandable pressure-sensitive adhesive layer can be thermally expanded by heating. The heat treatment method can be carried out by a suitable heating device such as a hot air dryer, a near-infrared lamp, or an air dryer. The heating temperature in the heat treatment may be equal to or higher than the foaming start temperature (thermal expansion start temperature) of the foaming agent (heat-expandable microsphere or the like) in the heat-expandable pressure-sensitive adhesive layer, but the conditions of the heat treatment may be as follows. Appropriate setting: reduction in area under the type of foaming agent (heat-expandable microspheres, etc.), including support, semi-conductor The heat resistance of the polishing body of the bulk wafer, the heating method (heat capacity, heating device, etc.), and the like. Typical heat treatment conditions are at a temperature of from 100 ° C to 250 ° C, from 1 second to 90 seconds (heating plate, etc.) or from 5 minutes to 15 minutes (hot air dryer, etc.). Further, the heat source during the heat treatment may also be an infrared lamp or a heated water.

(middle layer)

In the present embodiment, an intermediate layer (not shown) for the purpose of improving the adhesion or the peeling property after heating may be provided between the heat-expandable pressure-sensitive adhesive layer 2a and the support 2b. It is particularly preferable to provide a rubbery organic elastic intermediate layer as an intermediate layer. By providing the rubber-like organic elastic intermediate layer, when the semiconductor wafer 23 is attached to the temporary fixing member 2 (see FIG. 3A), the surface of the heat-expandable adhesive layer 2a can follow the surface shape of the semiconductor wafer 23 well. When the polishing body 26 after the polishing process is heated and peeled off from the temporary fixing member 2, the heating expansion of the heat-expandable pressure-sensitive adhesive layer 2a is highly (accurately) controlled, and the heat-expandable adhesive is adhered. The agent layer 2a preferentially and uniformly expands in the thickness direction.

Further, the rubber-like organic elastic intermediate layer may be sandwiched between one side or both sides of the support 2b.

The rubber-like organic elastic intermediate layer is preferably formed, for example, by a natural rubber, a synthetic rubber or a rubber-elastic synthetic resin having a D-type Shore D hardness of 50 or less according to ASTM D-2240, particularly 40 or less. Moreover, even if it has an intrinsic hard polymer, such as polyvinyl chloride, it can exhibit rubber elasticity by the combination with the admixtures, such as a plasticizer and softener. Such a composition can also be used as a constituent material of the rubbery organic elastic intermediate layer. use.

The rubber-like organic elastic intermediate layer can be formed by the following formation method, that is, for example, a coating liquid of a rubber-like organic elastic layer forming material containing a synthetic rubber or a rubber-elastic synthetic resin or the like is applied onto a substrate (coating method). A film formed of the rubber-like organic elastic layer forming material or a laminated film formed of a layer composed of the gel-like organic elastic layer forming material on one or more layers of the heat-expandable adhesive layer, which is formed in advance with the substrate (dry layer method); a method of coextruding a resin composition including a constituent material of a substrate and a resin composition containing the gel-like organic elastic layer forming material (co-extrusion method).

Further, the rubber-like organic elastic intermediate layer can be formed by an adhesive material containing a natural rubber, a synthetic rubber or a synthetic resin having rubber elasticity as a main component, and can also be a foamed film mainly composed of the component. Formed. The foaming can be carried out by a conventional method, for example, a mechanical stirring method, a method of generating a gas by a reaction, a method using a foaming agent, a method of removing a soluble substance, a method of spraying, a method of forming a synthetic foam, a sintering method, and the like. get on.

The thickness of the rubbery organic elastic intermediate layer is, for example, about 5 μm to 300 μm, and preferably about 20 μm to 150 μm. Further, in the case where the intermediate layer is, for example, a rubber-like organic elastic intermediate layer, when the thickness of the rubber-like organic elastic intermediate layer is too small, the three-dimensional structural change after the heating and foaming cannot be formed, and the peeling property is deteriorated.

The rubber-like organic elastic intermediate layer may be composed of a single layer or a layer of two or more layers.

Further, the intermediate layer may contain various additives (for example, a colorant, a tackifier, an extender, a filler, an adhesion promoter, a plasticizer, an anti-aging agent, etc.) within a range that does not impair the effect of the temporary fixing material. Antioxidants, surfactants, crosslinkers, etc.).

(Semiconductor wafer configuration step)

In the semiconductor wafer disposing step, a plurality of semiconductor wafers 23 are placed on the temporary fixing member 2 such that the active surface A2 faces the temporary fixing member 2 (see FIG. 3A). The arrangement of the semiconductor wafer 23 can be a conventional device such as a flip chip bonding machine or a pelletizer.

The layout or arrangement number of the arrangement of the semiconductor wafers 23 can be appropriately set depending on the shape, size, and number of packages of the temporary fixing members 2, and for example, can be arranged in a plurality of rows, and a plurality of columns are arranged in a matrix.

(sealing step)

In the sealing step, the sealing resin sheet 21 is laminated on the temporary fixing member 2 so as to cover the plurality of semiconductor wafers 23, and resin sealing is performed (see FIG. 3B). The method of laminating the sealing resin sheet 21 on the temporary fixing member 2 can be carried out under the same conditions as those of the first embodiment.

(sealing body forming step)

In the sealing body forming step, the sealing resin sheet 21 is thermally hardened to form a sealing body 25 (see FIG. 3B). The conditions of the thermosetting treatment of the sealing resin sheet 21 can be the same as those in the first embodiment.

(grinding step)

In the polishing step, the sealing resin sheet 21 of the sealing body 25 is exposed so that the surface 23S on the side opposite to the active surface A2 of the semiconductor wafer 23 is exposed to form a polishing. Body 26 (see Fig. 3C). Grinding can be carried out using a conventional polishing apparatus.

The minimum height difference between the surface 21S of the sealing resin sheet and the exposed surface 23S of the semiconductor wafer in the polishing body 26 is 10 μm or more, and is preferably 20 μm or more, and more preferably 30 μm or more. By setting the minimum height difference of the polishing surface G2 within the above range, the contraction force generated by the sealing resin sheet 21 acting on the polishing body 26 can be reduced, and the warpage of the polishing body 26 can be prevented.

(heat-expandable adhesive layer peeling step)

In the heat-expandable pressure-sensitive adhesive layer peeling step, the temporary heat retaining material 2 is heated to thermally expand the heat-expandable pressure-sensitive adhesive layer 2a, thereby peeling off between the heat-expandable pressure-sensitive adhesive layer 2a and the polishing body 26 (see FIG. 3D). Alternatively, the step of peeling off at the interface between the support 2b and the heat-expandable pressure-sensitive adhesive layer 2a may be suitably carried out, and then peeling is performed by thermal expansion at the interface between the heat-expandable pressure-sensitive adhesive layer 2a and the polishing body 26. In either case, the heat-expandable pressure-sensitive adhesive layer 2a can be thermally expanded to lower the adhesion, and the peeling at the interface between the heat-expandable pressure-sensitive adhesive layer 2a and the polishing body 26 can be easily performed. The conditions for thermal expansion can be those described in the column "The thermal expansion method of the heat-expandable adhesive layer".

In this step, the surface of the abrasive body 26 may be cleaned by plasma treatment or the like before the rewiring forming step in a state where the semiconductor wafer 23 is exposed.

(rewiring forming step)

In the present embodiment, it is preferable to further include a rewiring forming step of forming the rewiring 29 on the surface B2 on the active surface A2 side of the semiconductor wafer 23 of the polishing body 26. In the rewiring forming step, the above-mentioned heat-expandable adhesive is peeled off After the layer 2a, the rewiring 29 connected to the exposed semiconductor wafer 23 is formed on the polishing body 26 (see FIG. 3E).

In the method of forming the rewiring, for example, a metal sheet layer is formed on the exposed semiconductor wafer 23 by a conventional method such as vacuum film formation, and the rewiring 29 can be formed by a conventional method such as a semi-additive method.

Then, an insulating layer such as polyimide or PBO may be formed on the rewiring 29 and the polishing body 26.

(bump forming step)

Next, bump processing for forming the bumps 27 on the formed rewiring 29 can be performed (see FIG. 3F). The bump processing can be performed by a conventional method such as solder balls and solder plating. The material of the bump 27 can be suitably made of the same material as that of the first embodiment.

(wafer back protection step)

After the bumps 27 are formed, in order to protect the exposed surface 23S of the semiconductor wafer 23, the polishing surface G2 of the polishing body 26 may be resin-sealed again (see FIG. 3C). The sealing method is not particularly limited, and a liquid or film-like sealing resin is applied or adhered to the polishing surface G2 to dry and harden it. Again, this step can be carried out at any stage prior to the cutting step after the grinding step.

(cutting step)

Finally, the laminate of the semiconductor wafer 23, the sealing resin sheet 21, and the rewiring 29 is formed (see FIG. 3G). Thereby, the semiconductor package 28 which pulls the wiring out to the outside of the wafer region can be obtained in units of semiconductor wafers. The cutting method can be carried out in the same manner as in the first embodiment.

Example

Hereinafter, preferred embodiments of the invention will be described in detail by way of examples. However, the materials, blending amounts, and the like described in the examples are not limited to the meanings of the invention unless otherwise specified. Also, the portion means a part by weight.

[Example 1]

(Production of sealing resin sheet)

The following components were mixed by a mixer, melt-blended at 120 ° C for 2 minutes by a 2-axis blender, and then extruded by a T die, thereby producing a sealing resin sheet A having a thickness of 500 μm.

Epoxy resin: bisphenol F type epoxy resin (made by Nippon Steel Chemical Co., Ltd., YSLV-80XY (epoxy equivalent 200g/eq., softening point 80 °C)) 286 parts

Phenolic resin: phenol resin having a biphenyl aralkyl skeleton (manufactured by Mingwa Chemical Co., Ltd., MEH-7851-SS (hydroxy equivalent: 203 g/eq., softening point: 67 ° C)) 303 parts

Hardening accelerator: imidazole-based catalyst as a hardening catalyst (4PHZ-PW, manufactured by Shikoku Chemical Industry Co., Ltd.) 6 parts

Elastomer: styrene-isobutylene-styrene nitrile block copolymer (KANEKA (single), SIBSTAR 072T) 700 parts

Inorganic filler: spherical molten cerium oxide powder (manufactured by Electric Chemical Industry Co., Ltd., FB-9454, average particle size 20 μm) 600 parts

矽Case coupling agent: Epoxy decane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) 5 parts

Carbon black (Mitsubishi Chemical Co., Ltd., #20) 5 parts

[Embodiment 2]

(Production of sealing resin sheet)

The following components were mixed by a mixer, melt-blended at 120 ° C for 2 minutes by a 2-axis blender, and then extruded by a T die, whereby a sealing resin sheet C having a thickness of 500 μm was formed.

Solid epoxy resin (made by Nippon Kayaku Co., Ltd., EPPN-501-HY) 100 parts

Phenolic resin: phenol resin having a biphenyl aralkyl skeleton (manufactured by Mingwa Chemical Co., Ltd., MEH-7851-SS (hydroxy equivalent: 203 g/eq., softening point: 67 ° C)) 60 parts

Hardening accelerator: imidazole-based catalyst as a hardening catalyst (4PHZ-PW, manufactured by Shikoku Chemical Industry Co., Ltd.) 3 parts

Acrylic copolymer (copolymer composed of BA (butyl acrylate): AN (acrylonitrile): GMA (glycidyl acrylate) = 85:8:7 wt%, weight average molecular weight 800,000) 100 parts

Inorganic filler: spherical molten cerium oxide powder (made by Electric Chemical Industry Co., Ltd., FB-9454, average particle size 20 μm) 180 parts

Carbon black (Mitsubishi Chemical Co., Ltd., #20) 1 copy

[Comparative Example 1]

(Production of sealing resin sheet)

The following components were mixed by a mixer, melt-blended at 120 ° C for 2 minutes by a 2-axis blender, and then extruded by a T die, thereby producing a sealing resin sheet B having a thickness of 500 μm.

Epoxy resin: bisphenol F type epoxy resin (manufactured by Nippon Steel Chemical Co., Ltd., YSLV-80XY (epoxy equivalent 200 g/eq., softening point 80 ° C)) 169 parts

Phenolic resin: phenol resin having a biphenyl aralkyl skeleton (manufactured by Mingwa Chemical Co., Ltd., MEH-7851-SS (hydroxy equivalent: 203 g/eq., softening point: 67 ° C)) 179 parts

Hardening accelerator: imidazole-based catalyst as a hardening catalyst (4PHZ-PW, manufactured by Shikoku Chemical Industry Co., Ltd.) 6 parts

Elastomer: styrene-isobutylene-styrene nitrile block copolymer (KANEKA (single), SIBSTAR 072T) 152 parts

Inorganic filler: spherical molten cerium oxide powder (manufactured by Electric Chemical Industry Co., Ltd., FB-9454, average particle size 20 μm) 2400 parts

矽Case coupling agent: Epoxy decane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) 5 parts

Carbon black (Mitsubishi Chemical Co., Ltd., #20) 5 parts

Flame retardant: azo-phosphorus compound (Fushi Pharmaceutical Co., Ltd., FP-100) 89 parts

(Measurement of storage elastic modulus of sealing resin sheet)

The measurement of the storage elastic modulus was carried out using a solid viscoelasticity measuring device (manufactured by Rheometric Scientific: Form: RSA-III). Specifically, it was obtained by heating each of the sealing resin sheets at 150 ° C for 1 hour, and the sample size was made into a length of 400 mm × a width of 2 mm × a thickness of 80 μm to obtain a measurement sample. The measurement elastic modulus and the loss elastic modulus are measured in a temperature range of -50 to 300 ° C under the conditions of a frequency of 1 Hz, a temperature increase rate of 10 ° C / min, and a strain of 0.05%. And read the storage elastic modulus (E') at 25 °C.

(Measurement of Shore D hardness of sealing resin sheet)

It is obtained by laminating each sealing resin sheet to a thickness of 2 mm using a laminator, heating the laminate at 150 ° C to thermally harden it, and using a hardness meter (MITUTOYO Co., Ltd., according to JIS K 7215, Plastic hardness tester), read the measured value at 25 °C.

(Production of semiconductor package)

Flip-chip mounted on a tantalum insert to mount a semiconductor wafer of the following specifications, preparing a wafer-mounting insert using a bisphenol A epoxy-based hardenable underfill source electrode between the wafer-insert .

<Semiconductor wafer>

Semiconductor wafer size: 7.3mm □ (thickness 400μm)

Bump material: Cu 30μm thick, Sn-Ag 15μm thick

Number of bumps: 544 bumps

Bump pitch: 50μm

Number of wafers: 16 (4 x 4)

<矽 Insert>

Diameter: 8 inches

Thickness: 730μm

Electrode: 矽 perforation (diameter: 30μm)

On the obtained wafer mounting insert, the sealing resin sheets A to C were respectively adhered by vacuum pressing under the conditions of heat and pressure shown below.

<Adhesive condition>

Temperature: 90 ° C

Pressure: 0.5MPa

Vacuum degree: 2000Pa

Press time: 3 points

After opening to the atmosphere, the sealing resin sheet was thermally cured in a hot air dryer at 180 ° C for 1 hour to obtain a sealed body. Subsequently, it was ground using a polishing apparatus (manufactured by DISCO, surface planer "DFS8910"), whereby the sealing body was thinned together under the conditions of a peripheral speed of the grinding turning tool of 1000 m/min, a feeding pitch of 100 μm, and a cutting depth of 10 μm. The thickness of the semiconductor wafer to the semiconductor wafer was 100 μm, whereby an abrasive body was produced.

The exposed surface of the obtained abrasive insert (the side opposite to the surface on which the sealing resin sheet was pasted) was polished by (DISCO, "DGP8761") until the thickness of the tantalum insert was 100 μm.

Coating polyglycine (3,4',3,4'-biphenyltetracarboxylic dianhydride with 4,4'-diamine diphenyl ether and p-phenylenediamine on the polished surface of the ruthenium insert Then, it is thermally cured to form a polyimide layer having a thickness of 10 μm. At a position corresponding to the perforation of the crucible, an opening is formed by laser processing to expose the aperture. On the surface of the polyimide layer containing the opening, a gold film or a nickel film is sequentially formed by plating. Further, sputtering is performed in the order of chromium and copper to form a seed film (the thickness of the chromium layer is 20 nm, and the thickness of the copper layer is 100 nm), and a rewiring layer having a predetermined wiring pattern is formed by electrolytic copper plating. Into a semiconductor package.

(measurement of the minimum height difference of the polished surface)

The semiconductor package of the embodiment and the comparative example was used, and the surface of the sealing resin sheet and the exposure of the semiconductor wafer in the polished surface of the semiconductor package were measured using a stylus type surface shape measuring device ("Dektak 8", manufactured by ULVAC Co., Ltd.). The minimum height difference of the face. Specifically, as shown in FIG. 4, one line per time And scanning the surface in a row to include the rows and columns of the semiconductor wafers 13 arranged in a matrix, thereby obtaining the surface shape of the polished surface, and calculating the minimum height difference based on the surface shape.

(Evaluation of warpage of semiconductor package)

Using the semiconductor packages of the examples and the comparative examples, as shown in FIG. 4, the surface was scanned twice along the diagonal of the matrix of the semiconductor wafer, thereby obtaining the surface shape along each diagonal line, and calculating a total of 4 points. The absolute value of the height difference between the wafer end height and the center portion is taken as the surface warpage amount. When the surface warpage amount of the semiconductor package was 1.5 mm or less, it was evaluated as "○", and when it was more than 1.5 mm, it was evaluated as "X". The results are shown in Table 1, respectively.

As can be seen from Table 1, in the first and second embodiments, since the minimum height difference after polishing is 10 μm or more, it is possible to produce a highly reliable semiconductor package which suppresses warpage of the semiconductor package and has a good yield. On the other hand, in the semiconductor package of Comparative Example 1, since the minimum height difference is less than 10 μm, the semiconductor package is warped, which is not preferable in terms of productivity and reliability.

11‧‧‧ Sealing resin sheet

12A‧‧‧Semiconductor Wafer

13‧‧‧Semiconductor wafer

15‧‧‧ Sealing body

Claims (10)

A method of manufacturing a semiconductor package, comprising: a sealing body forming step of forming a sealing body in which one or more semiconductor wafers are embedded in a sealing resin sheet; and a polishing step of polishing the sealing resin sheet of the sealing body to form the semiconductor The surface opposite to the active surface of the wafer is exposed to form a polishing body, and the minimum height difference between the surface of the sealing resin sheet and the exposed surface of the semiconductor wafer in the polishing body is 10 μm or more. The method for producing a semiconductor package according to claim 1, wherein the sealing resin sheet after the heat hardening treatment at 150 ° C for 1 hour has a Shore D hardness of 20 or more and 60 or less at 25 ° C. The method for producing a semiconductor package according to claim 1, wherein the sealing resin sheet after the heat curing treatment at 150 ° C for 1 hour has a storage elastic modulus of 0.1 GPa or more and 3 GPa or less at 25 ° C. The method of manufacturing a semiconductor package according to claim 1, wherein in the sealing body forming step, the sealing resin is formed by embedding the semiconductor wafer in which the flip chip is connected to the semiconductor wafer into the sealing resin sheet. The method of manufacturing a semiconductor package according to claim 1, wherein in the sealing body forming step, the semiconductor wafer fixed to the temporary fixing material is embedded in the sealing resin sheet to form the sealing body. A method of manufacturing a semiconductor package according to any one of claims 1 to 5, Further, a back grinding step is performed to polish the active surface side surface of the semiconductor wafer of the polishing body after the polishing step. The method of manufacturing a semiconductor package according to any one of claims 1 to 5, further comprising a rewiring forming step of forming a rewiring on an active surface side surface of the semiconductor wafer of the polishing body after the polishing step. The method of manufacturing a semiconductor package according to claim 6, further comprising a rewiring forming step of forming a rewiring on an active surface side surface of the semiconductor wafer of the polishing body after the back grinding step. A method of manufacturing a semiconductor package according to claim 7, wherein a plurality of the semiconductor wafers are used, and further comprising a dicing step of dicing the polishing body in units of the desired semiconductor wafer after the rewiring forming step. A method of manufacturing a semiconductor package according to claim 8, wherein a plurality of the semiconductor wafers are used, and further comprising a dicing step of dicing the polishing body in units of the desired semiconductor wafer after the rewiring forming step.