JP2015053468A - Method for manufacturing semiconductor package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor package capable of forming an intended circuit element with a high yield, after a sealant using a sealing resin sheet, is ground.SOLUTION: A method for manufacturing a semiconductor package comprises: a sealant formation step for forming a sealant in which one or a plurality of semiconductor chips are embedded in a sealing resin sheet; and a grinding step for grinding the sealing resin sheet of the sealant so that a surface on the opposite side of an active surface of the semiconductor chip is exposed, to form a ground body. A maximum difference of elevation between the surface of the sealing resin sheet on the ground body and an exposed surface of the semiconductor chip is equal to or less than 10 μm.

Description

  The present invention relates to a method for manufacturing a semiconductor package.

  In recent years, there is an increasing demand for downsizing, lightening, and high functionality of electronic devices, and accordingly, packages that make up electronic devices are also required to be downsized, thinned, and mounted with high density.

  For the manufacture of a semiconductor package, typically, an electronic component fixed to a substrate, a temporary fixing material, or the like is sealed with a sealing resin, and the sealed product is packaged in units of electronic components as necessary. The procedure of dicing is adopted. In such a process, in order to meet the above requirements, a technique for reducing the thickness by grinding a sealing material after resin sealing has been proposed (for example, Patent Documents 1 and 2). Thinning by grinding is also important in the manufacturing process of thin semiconductor packages such as flip chip BGA (Ball Grid Array), flip chip SiP (System in Package), fan-in type wafer level package, and fan out type wafer level package. Become an element.

Japanese Patent No. 3420748 Patent No. 3666576

  However, after grinding the sealing material, it is possible to form a desired rewiring or bump even if a process for forming a circuit element such as a rewiring or a bump on the surface opposite to the ground surface is performed. It has been found that there may be a problem that the rewiring is peeled off after the rewiring is formed. These inconveniences are not recognized by the techniques of Patent Documents 1 and 2 described above, and their solutions are desired.

  The objective of this invention is providing the manufacturing method of the semiconductor package which can form the target circuit element with a sufficient yield after grinding of the sealing material using the sealing resin sheet.

  As a result of intensive studies based on the idea that the state of the grinding surface affects the formation of circuit elements on the surface opposite to the grinding surface, the present inventors have found that the above problem can be solved by the following configuration. The present invention has been completed.

That is, the present invention provides a sealing body forming step of forming a sealing body in which one or a plurality of semiconductor chips are embedded in a sealing resin sheet, and the sealing resin sheet of the sealing body is activated by the semiconductor chip. A grinding step of forming a grinding body by grinding so that a surface opposite to the surface is exposed,
In this method, the maximum height difference between the surface of the sealing resin sheet and the exposed surface of the semiconductor chip in the grinding body is 10 μm or less.

  The inventors of the present invention have found that the cause of the trouble in forming the circuit element is the state of the grinding surface of the grinding body opposite to the surface on which the circuit element is formed, particularly the level difference of the surface. When forming a circuit element such as rewiring or bump on the surface opposite to the grinding surface of the grinding body (hereinafter also simply referred to as “back surface”), if the grinding surface is a fixed surface, the effect of steps on the grinding surface Extends to the back surface, and a step is also formed on the back surface. If you try to form a circuit element with a step on the back side, the adhesion of the rewiring to the wafer will decrease due to the effect of the step, and it will be easy to peel off, or positioning of bump formation will be difficult. The yield of forming circuit elements on the back surface is reduced. In the manufacturing method, the maximum height difference (hereinafter also simply referred to as “maximum height difference”) between the surface of the encapsulating resin sheet and the exposed surface of the semiconductor chip in the grinding body is 10 μm or less. The circuit elements on the back surface can be formed with good yield. If the maximum height difference exceeds 10 μm, there may be a problem in forming the circuit elements described above.

  It is preferable that the Shore D hardness at 25 ° C. of the encapsulating resin sheet after the thermosetting treatment at 150 ° C. for 1 hour is 60 or more. Moreover, it is preferable that the storage elastic modulus in 25 degreeC of the said sealing resin sheet after performing a thermosetting process at 150 degreeC for 1 hour is 3 GPa or more. According to the study by the present inventors, one of the main causes of the level difference of the grinding surface of the grinding body is the difference between the hardness of the sealing resin sheet (after thermosetting treatment) in the sealing body and the hardness of the semiconductor chip (hereinafter, It is presumed that it is simply called “hardness difference”. That is, it can be considered that a correlation is established that the difference in hardness is large when the hardness difference is large, and the difference is small when the hardness difference is small. In the manufacturing method, by setting the Shore D hardness or the storage elastic modulus in the above range, the hardness difference can be reduced to reduce the maximum height difference in the grinding surface of the grinding body. The formation efficiency of the circuit element can be improved.

  In the sealing body forming step, the semiconductor chip flip chip connected to a semiconductor wafer may be embedded in the sealing resin sheet to form the sealing body, or the semiconductor fixed to a temporary fixing material The sealing body may be formed by embedding a chip in the sealing resin sheet. The former is suitable for a chip-on-wafer process in which semiconductor chips are aligned on a wafer to produce a semiconductor device, and the latter is suitable for a fan-out type wafer level package process. Even if the sealing body is formed in any form, circuit elements can be formed on the back surface of the grinding body with good yield.

  After the grinding step, a rewiring forming step of forming a rewiring on the active surface side surface of the semiconductor chip of the grinding body may be further included.

In the manufacturing method, a plurality of the semiconductor chips are used,
After the rewiring forming step, a dicing step of dicing the ground body in units of a target semiconductor chip may be further included.

It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the sealing resin sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is sectional drawing which shows typically 1 process of the manufacturing method of the semiconductor package which concerns on another one Embodiment of this invention. It is a top view which shows typically the procedure which measures the maximum height difference in the grinding surface of a grinding body.

  An embodiment of a method for 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, parts unnecessary for the description are omitted, and there are parts shown enlarged or reduced for easy explanation. The terms indicating the positional relationship such as up and down are merely used for ease of explanation, and are not intended to limit the configuration of the present invention.

<First Embodiment>
[Semiconductor package manufacturing method]
A method of manufacturing a semiconductor package according to this embodiment using a sealing resin sheet will be described with reference to FIGS. 1A to 1G. FIG. 1A to FIG. 1G are cross-sectional views schematically showing one step of a method for manufacturing a semiconductor package according to an embodiment of the present invention. In the first embodiment, a semiconductor chip is manufactured by sealing a semiconductor chip mounted on a semiconductor wafer with a sealing resin sheet. The semiconductor package manufacturing method according to the first embodiment is suitable for a chip-on-wafer (COW) process.

(Chip mounting wafer preparation process)
In the chip mounting wafer preparation step, a semiconductor wafer 12A in which a plurality of semiconductor chips 13 are flip-chip connected is prepared (see FIG. 1A). The semiconductor chip 13 can be formed by dicing a semiconductor wafer on which a predetermined circuit is formed by a known method. For mounting the semiconductor chip 13 on the semiconductor wafer 12A, a known device such as a flip chip bonder can be used. In the present embodiment, flip chip connection is employed in which the active surface A1 on which the protruding electrode 13a of the semiconductor chip 13 is formed faces the semiconductor wafer 12A. The semiconductor chip 13 and the semiconductor wafer 12A are electrically connected to each other through bump electrode electrodes 13a formed on the semiconductor chip 13 and through electrodes 12a provided on the semiconductor wafer 12A. As the through-electrode 12a, a TSV (Through Silicon Via) type electrode can be preferably used.

  In addition, an underfill material 14 is filled between the semiconductor chip 13 and the semiconductor wafer 12A in order to reduce the difference in thermal expansion coefficient between the semiconductor chip 13 and the semiconductor wafer 12A, and in particular, to prevent the occurrence of cracks or the like at the connection site. A known material may be used as the underfill material 14. The underfill material 14 may be arranged by injecting the liquid underfill material 14 between the semiconductor chips 13 after the semiconductor chip 13 is mounted on the semiconductor wafer 12A. The semiconductor chip with the sheet-like underfill material 14 may be disposed. 13 or the semiconductor wafer 12A may be prepared, and the semiconductor chip 13 and the semiconductor wafer 12A may be connected to each other.

(Sealing process)
In the sealing step, the sealing resin sheet 11 is laminated on the semiconductor wafer 12A so as to embed the semiconductor chip 13, and the semiconductor chip 13 is resin-sealed with the sealing resin sheet (see FIG. 1B). The sealing resin sheet 11 functions as a sealing resin for protecting the semiconductor chip 13 and its accompanying elements from the external environment.

  The method for laminating the sealing resin sheet 11 is not particularly limited, and a melt-kneaded product of the resin composition for forming the sealing resin sheet is extruded, and the extruded product is placed on the semiconductor wafer 12A and pressed. By applying the resin composition for forming the encapsulating resin sheet 11 and laminating at once or the resin composition for forming the encapsulating resin sheet 11 on the release treatment sheet, the coating film is dried. Examples include a method of forming the sealing resin sheet 11 and transferring the sealing resin sheet 11 onto the semiconductor wafer 12A.

  In the present embodiment, by adopting the sealing resin sheet 11, the semiconductor chip 13 can be embedded simply by sticking the semiconductor chip 13 on the semiconductor wafer 12 </ b> A, thereby improving the production efficiency of the semiconductor package. Can do. In this case, the sealing resin sheet 11 can be laminated on the semiconductor wafer 12A by a known method such as hot pressing or laminator. As the hot press conditions, the temperature is, for example, 40 to 120 ° C., preferably 50 to 100 ° C., the pressure is, for example, 50 to 2500 kPa, preferably 100 to 2000 kPa, and the time is, for example, 0 .3 to 10 minutes, preferably 0.5 to 5 minutes. Further, in consideration of improvement in the adhesion and followability of the sealing resin sheet 11 to the semiconductor chip 13 and the semiconductor wafer 12A, it is preferable to press under reduced pressure conditions (for example, 10 to 2000 Pa).

(Sealing body forming process)
In the sealing body forming step, the sealing resin sheet is thermally cured to form the sealing body 15 in which the semiconductor chip 13 is embedded in the sealing resin sheet 11 (see FIG. 1B). The conditions for the thermosetting treatment of the sealing resin sheet are preferably 100 to 200 ° C., more preferably 120 to 180 ° C. as the heating temperature, and preferably 10 to 180 minutes, more preferably 30 to 120 minutes as the heating time. You may pressurize as needed. In the pressurization, preferably 0.1 MPa to 10 MPa, more preferably 0.5 MPa to 5 MPa can be employed.

(Grinding process)
In the grinding step, the sealing resin sheet 11 of the sealing body 15 is ground so that the surface opposite to the active surface A of the semiconductor chip 13 is exposed to form a grinding body 16A (see FIG. 1C). During grinding, the semiconductor chip 13 may be ground together with the sealing resin sheet 11 as shown in FIG. 1C, or only the sealing resin sheet 11 may be ground. Grinding may be performed using a known grinding apparatus. A procedure for forming the grinding body 16A by grinding the surface of the sealing body while feeding the sealing body 15 while rotating a grinding tool such as a diamond tool can be suitably employed.

  The maximum height difference between the surface 11S of the sealing resin sheet and the exposed surface 13S of the semiconductor chip in the grinding body 16A is 10 μm or less, preferably 7 μm or less, more preferably 5 μm or less. By setting the maximum height difference on the grinding surface G1 within the above range, the influence on the back surface B1 of the step in the grinding surface G1 of the grinding body 16B (see FIG. 1E) obtained by grinding the semiconductor wafer 12A can be reduced, and the yield is improved. A rewiring 19 can be formed. In addition, although the minimum of the said minimum height difference is so preferable that it is small and 0 micrometer is preferable, 0.1 micrometer or more may be sufficient from a physical limit.

(Back grinding process)
In the back surface grinding step, the surface opposite to the grinding surface G1 of the grinding body 16A (that is, the back surface B1) is ground (see FIG. 1D). As a result, the exposed surface of the semiconductor wafer 12A is ground, and a thinned semiconductor wafer 12B can be obtained. What is necessary is just to change the thickness of the semiconductor wafer 12B after grinding according to the specification of the target package, for example, 25-200 micrometers is preferable and 50-100 micrometers is more preferable. Grinding may be performed using a known grinding apparatus. Since the maximum height difference of the ground surface G1 is small, smooth back surface grinding can be performed without separately preparing a back surface grinding tape for fixing the grinding body 16A, thereby improving production efficiency and reducing costs. be able to. Of course, the back surface grinding tape may be used to fix the grinding body 16A. In this case, contamination of the grinding surface G1 during back surface grinding can be prevented. A well-known thing can be used for the tape for back surface grinding.

(Rewiring process)
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 chip 13 of the grinding body 16B (see FIG. 1E). In the rewiring forming step, after the thinned semiconductor wafer 12B is formed by back grinding, the rewiring 19 connected to the through electrode 12a of the semiconductor wafer 12B is formed on the grinding body 16B.

  As a method for forming the rewiring, for example, a metal seed layer is formed on the exposed semiconductor wafer 12B using a known method such as a vacuum film forming method, and the rewiring is performed by a known method such as a semi-additive method. The wiring 19 can be formed.

  After this, an insulating layer such as polyimide or PBO may be formed on the rewiring 19 and the grinding body 16B.

(Bump formation process)
Next, bumping processing for forming bumps 17 on the formed rewiring 19 may be performed (see FIG. 1F). The bumping process can be performed by a known method such as a solder ball or solder plating. The material of the bump is not particularly limited. For example, a tin-lead metal material, a tin-silver metal material, a tin-silver-copper metal material, a tin-zinc metal material, a tin-zinc-bismuth metal material, etc. Solders (alloys), gold-based metal materials, copper-based metal materials, and the like.

(Chip back surface protection process)
After forming the bumps 17, in order to protect the exposed surface 13S of the semiconductor chip 13, the grinding surface G1 (see FIG. 1C) of the grinding body 16A may be resin-sealed again. The sealing method is not particularly limited, and a known liquid or film-like sealing resin may be applied or bonded to the grinding surface G1, dried, and cured. This step may be performed at any stage after the grinding step and before the dicing step.

(Dicing process)
Subsequently, the grinding body 16C may be diced through bump formation including elements such as the sealing resin sheet 11, the semiconductor wafer 12B, and the semiconductor chip 13 (see FIG. 1G). As a result, the semiconductor package 18 can be obtained in units of the target semiconductor chip 13. In FIG. 1G, dicing is performed corresponding to one semiconductor chip, but dicing may be performed with two or more semiconductor chips as a unit. Dicing is usually performed after the grinding body 16 is fixed by a conventionally known dicing sheet. The alignment of the cut portion may be performed by image recognition using direct illumination or indirect illumination.

  In this step, for example, a cutting method called full cut for cutting up to a dicing sheet can be adopted. It does not specifically limit as a dicing apparatus used at this process, A conventionally well-known thing can be used.

  In addition, when expanding a grinding body following a dicing process, this expansion can be performed using a conventionally well-known expanding apparatus. The expanding device includes a donut-shaped outer ring that can push down the dicing sheet through the dicing ring, and an inner ring that has a smaller diameter than the outer ring and supports the dicing sheet. By this expanding process, it is possible to prevent the adjacent semiconductor packages 18 from coming into contact with each other and being damaged.

(Board mounting process)
If necessary, a substrate mounting step of mounting the semiconductor package 18 obtained above on a separate substrate (not shown) can be performed. For mounting the semiconductor package 18 on the substrate, a known device such as a flip chip bonder or a die bonder can be used.

[Sealing resin sheet]
The sealing resin sheet according to the present embodiment will be described with reference to FIG. 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. Note that a release treatment may be applied to the support 11a in order to easily peel off the sealing resin sheet 11.

  Moreover, it is preferable that the Shore D hardness in 25 degreeC of the sealing resin sheet 11 after performing a thermosetting process at 150 degreeC for 1 hour is 60 or more, and it is more preferable that it is 70 or more. The upper limit of the Shore D hardness is preferably 92 or less. Furthermore, it is preferable that the storage elastic modulus in 25 degreeC of the sealing resin sheet 11 after performing a thermosetting process at 150 degreeC for 1 hour is 3 GPa or more, and it is more preferable that it is 10 GPa or more. The upper limit of the storage elastic modulus is preferably 30 GPa or less. By setting the Shore D hardness and the storage elastic modulus of the encapsulating resin sheet 11 after the thermosetting treatment to the above ranges, the hardness difference can be reduced, and thereby the maximum height difference can be reduced.

(Resin composition forming a sealing resin sheet)
The resin composition for forming the sealing resin sheet is not particularly limited as long as it has the above-described characteristics and can be used for resin sealing of electronic components such as semiconductor chips. An epoxy resin composition containing an A component to an E component is preferable. The C component may or may not be added as necessary.
A component: Epoxy resin B component: Phenol resin C component: Elastomer D component: Inorganic filler E component: Curing accelerator

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

  From the viewpoint of ensuring the toughness after curing of the epoxy resin and the reactivity of the epoxy resin, those having an epoxy equivalent of 150 to 250 and a softening point or melting point of 50 to 130 ° C. are preferably solid, and in particular, from the viewpoint of reliability. Therefore, triphenylmethane type epoxy resin, cresol novolac type epoxy resin, and biphenyl type epoxy resin are preferable.

  Also, from the viewpoint of low stress, a modified bisphenol A type epoxy resin having a flexible skeleton such as an acetal group or a polyoxyalkylene group is preferable, and a modified bisphenol A type epoxy resin having an acetal group is in a liquid state and is easy to handle. Therefore, it can be particularly preferably used.

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

(B component)
The phenol resin (component B) is not particularly limited as long as it causes 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 resole resin, or the like is used. These phenolic resins may be used alone or in combination of two or more.

  From the viewpoint of reactivity with the epoxy resin (component A), it is preferable to use a phenolic resin having a hydroxyl equivalent weight of 70 to 250 and a softening point of 50 to 110 ° C., among which the curing reactivity is high. A phenol novolac resin can be preferably used. From the viewpoint of reliability, low hygroscopic materials such as phenol aralkyl resins and biphenyl aralkyl resins can also be suitably used.

  From the viewpoint of curing reactivity, the blending ratio of the epoxy resin (component A) and the phenol resin (component B) is a hydroxyl group in the phenol resin (component B) with respect to 1 equivalent of the epoxy group in the epoxy resin (component A). It is preferable to mix | blend so that it may become 0.7-1.5 equivalent, More preferably, it is 0.9-1.2 equivalent.

  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, and more preferably 3.0% by weight or more. Adhesive force with respect to the semiconductor chip 13, the semiconductor wafer 12A, etc. is obtained favorably as it is 2.5 wt% or more. The total content of the epoxy resin and the phenol resin in the sealing resin sheet 11 is preferably 20% by weight or less, and more preferably 10% by weight or less. Hygroscopicity can be reduced as it is 20 weight% or less.

(C component)
The elastomer (component C) used together with the epoxy resin (component A) and the phenol resin (component B) provides the epoxy resin composition with the flexibility necessary for sealing electronic components with a sealing resin sheet. The structure is not particularly limited as long as such an effect is exhibited. For example, various acrylic copolymers such as polyacrylates, styrene acrylate copolymers, butadiene rubber, styrene-butadiene rubber (SBR), ethylene-vinyl acetate copolymer (EVA), isoprene rubber, acrylonitrile rubber, etc. Polymers can be used. Among them, from the viewpoint that it is easy to disperse in the epoxy resin (component A), and because the reactivity with the epoxy resin (component A) is high, the heat resistance and strength of the resulting sealing resin sheet can be improved. It is preferable to use an acrylic copolymer. These may be used alone or in combination of two or more.

  The acrylic copolymer can be synthesized, for example, by radical polymerization of an acrylic monomer mixture having a predetermined mixing ratio by a conventional method. As a method for radical polymerization, a solution polymerization method in which an organic solvent is used as a solvent or a suspension polymerization method in which polymerization is performed while dispersing raw material monomers in water are used. As a polymerization initiator used in that case, 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, peroxide polymerization initiators such as benzoyl peroxide and methyl ethyl ketone peroxide are used. In the case of suspension polymerization, it is desirable to add a dispersing agent such as polyacrylamide or polyvinyl alcohol.

  Content of an elastomer (C component) is 15 to 30 weight% of the whole epoxy resin composition. When the content of the elastomer (component C) is less than 15% by weight, it becomes difficult to obtain the flexibility and flexibility of the sealing resin sheet 11, and it is also difficult to perform resin sealing while suppressing warping of the sealing resin sheet. It becomes. On the other hand, when the content exceeds 30% by weight, the melt viscosity of the sealing resin sheet 11 is increased, the embedding property of the semiconductor chip 13 is lowered, and the strength and heat resistance of the cured body of the sealing resin sheet 11 are reduced. There is a tendency to decrease.

  The weight ratio of the elastomer (component C) to the epoxy resin (component A) (weight of component C / weight of component A) is preferably set in the range of 3 to 4.7. 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 chip 13 tends to be inferior. Because it is.

(D component)
The inorganic filler (component D) is not particularly limited, and various conventionally known fillers can be used. For example, quartz glass, talc, silica (fused silica, crystalline silica, etc.), alumina, nitriding Examples thereof include aluminum, silicon nitride, and boron nitride powders. These may be used alone or in combination of two or more.

  Among these, silica powder is used in that the internal stress is reduced by reducing the coefficient of thermal expansion of the cured product of the epoxy resin composition, and as a result, warpage of the sealing resin sheet 11 after sealing of the electronic component can be suppressed. It is preferable to use a fused silica powder among the silica powders. Examples of the fused silica powder include spherical fused silica powder and crushed fused silica powder. From the viewpoint of fluidity, it is particularly preferable to use a spherical fused silica powder. Among them, those having an average particle size in the range of 0.1 to 30 μm are preferably used, and those having a range of 1 to 20 μm are more preferable.

  The average particle diameter can be derived by using a sample arbitrarily extracted from the population and measuring it using a laser diffraction / scattering particle size distribution measuring apparatus.

  Content of an inorganic filler (D component) becomes like this. Preferably it is 70 to 95 weight% of the whole epoxy resin composition, More preferably, it is 75 to 92 weight%, More preferably, it is 80 to 90 weight%. When the content of the inorganic filler (component D) is less than 50% by weight, the linear expansion coefficient of the cured product of the epoxy resin composition increases, and thus the warpage of the sealing resin sheet 11 tends to increase. On the other hand, since the softness | flexibility and fluidity | liquidity of the sealing resin sheet 11 will worsen when the said content exceeds 90 weight%, the tendency for adhesiveness with a semiconductor chip to fall is seen.

(E component)
The curing accelerator (component E) is not particularly limited as long as it allows curing of the epoxy resin and the phenol resin, but from the viewpoint of curability and storage stability, triphenylphosphine or tetraphenylphosphonium tetraphenyl. Organic phosphorus compounds such as borates and imidazole compounds are preferably used. These curing accelerators may be used alone or in combination with other curing accelerators.

  It is preferable that content of a hardening accelerator (E component) is 0.1-5 weight part with respect to a total of 100 weight part of an epoxy resin (A component) and a phenol resin (B component).

(Other ingredients)
In addition to the A component to the E component, a flame retardant component may be added to the epoxy resin composition. As the flame retardant composition, various metal hydroxides such as aluminum hydroxide, magnesium hydroxide, iron hydroxide, calcium hydroxide, tin hydroxide, and complex metal hydroxide can be used.

  The average particle diameter of the metal hydroxide is preferably 1 to 10 μm, more preferably 2 to 5 μm, from the viewpoint of ensuring appropriate fluidity when the epoxy resin composition is heated. It is. When the average particle size of the metal hydroxide is less than 1 μm, it becomes difficult to uniformly disperse in the epoxy resin composition, and the fluidity during heating of the epoxy resin composition tends to be insufficient. Moreover, since the surface area per addition amount of a metal hydroxide (E component) will become small when an average particle diameter exceeds 10 micrometers, the tendency for a flame-retardant effect to fall is seen.

  As the flame retardant component, a phosphazene compound can be used in addition to the metal hydroxide. As phosphazene compounds, for example, SPR-100, SA-100, SP-100 (above, Otsuka Chemical Co., Ltd.), FP-100, FP-110 (above, Fushimi Pharmaceutical Co., Ltd.) and the like are available as commercial products. is there.

（式（１）中、ｎは３〜２５の整数であり、Ｒ^１及びＲ^２は同一又は異なって、アルコキシ基、フェノキシ基、アミノ基、水酸基及びアリル基からなる群より選択される官能基を有する１価の有機基である。）

（式（２）中、ｎ及びｍは、それぞれ独立して３〜２５の整数である。Ｒ^３及びＲ^５は同一又は異なって、アルコキシ基、フェノキシ基、アミノ基、水酸基及びアリル基からなる群より選択される官能基を有する１価の有機基である。Ｒ^４は、アルコキシ基、フェノキシ基、アミノ基、水酸基及びアリル基からなる群より選択される官能基を有する２価の有機基である。） The phosphazene compound represented by the formula (1) or the formula (2) is preferable from the viewpoint of exhibiting a flame retardant effect even in a small amount, and the content of phosphorus element contained in these phosphanzene compounds is 12% by weight or more. Is preferred.

(In the formula (1), n is an integer of 3 to 25, R ¹ and R ² are the same or different and are selected from the group consisting of an alkoxy group, a phenoxy group, an amino group, a hydroxyl group and an allyl group. A monovalent organic group having

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

（式（３）中、ｎは３〜２５の整数であり、Ｒ^６及びＲ^７は同一又は異なって、水素、水酸基、アルキル基、アルコキシ基又はグリシジル基である。） Moreover, it is preferable to use the cyclic phosphazene oligomer represented by Formula (3) from a viewpoint of stability and suppression of void formation.

(In Formula (3), n is an integer of 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.)

  As the cyclic phosphazene oligomer represented by the above formula (3), for example, FP-100, FP-110 (above, Fushimi Pharmaceutical Co., Ltd.) and the like are commercially available.

  The content of the phosphazene compound includes the epoxy resin (component A), phenol resin (component B), elastomer (component D), curing accelerator (component E) and phosphazene compound (other components) contained in the epoxy resin composition. It is preferable that it is 10 to 30 weight% of the whole organic component containing. That is, when the content of the phosphazene compound is less than 10% by weight of the total organic component, the flame retardancy of the sealing resin sheet 11 is reduced and the unevenness followability to an adherend (semiconductor wafer on which a semiconductor chip is mounted) or the like. Tends to decrease, and voids tend to occur. When the content exceeds 30% by weight of the whole organic component, tackiness is likely to occur on the surface of the sealing resin sheet 11, and the workability tends to be lowered, such as difficulty in alignment with the adherend.

  Moreover, the said metal hydroxide and the phosphazene compound can be used together, and the sealing resin sheet 11 excellent in the flame retardance can also be obtained, ensuring the flexibility required for sheet sealing. By using both in combination, sufficient flame retardancy when only the metal hydroxide is used and sufficient flexibility can be obtained when only the phosphazene compound is used.

  Among the above flame retardants, organic flame retardants are used from the viewpoint of the deformability of the sealing resin sheet at the time of molding the resin seal, the conformity to the unevenness of the adherend, and the adhesion to the semiconductor chip or the semiconductor wafer. In particular, phosphazene flame retardants are preferably used.

  In addition to the above components, the epoxy resin composition can be appropriately mixed with other additives such as a pigment including carbon black as necessary.

(Method for producing sealing resin sheet)
A method for producing the sealing resin sheet will be described below. First, an epoxy resin composition is prepared by mixing the above-described components. The mixing method is not particularly limited as long as each component is uniformly dispersed and mixed. Thereafter, for example, a varnish in which each component is dissolved or dispersed in an organic solvent or the like is applied to form a sheet. Alternatively, a kneaded material may be prepared by directly kneading each compounding component with a kneader or the like, and the kneaded material thus obtained may be extruded to form a sheet.

  As a specific production procedure using a varnish, the above components A to E and, if necessary, other additives are appropriately mixed according to a conventional method, and uniformly dissolved or dispersed in an organic solvent to prepare a varnish. Subsequently, the sealing resin sheet 11 can be obtained by applying the varnish on a support such as polyester and drying it. If necessary, a release sheet such as a polyester film may be bonded to protect the surface of the sealing resin sheet. The release sheet peels at the time of sealing.

  The organic solvent is not particularly limited, and various conventionally known organic solvents such as methyl ethyl ketone, acetone, cyclohexanone, dioxane, diethyl ketone, toluene, ethyl acetate and the like can be used. These may be used alone or in combination of two or more. Usually, it is preferable to use an organic solvent so that the solid content concentration of the varnish is in the range of 30 to 60% by weight.

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

  On the other hand, when kneading is used, the above components A to E and, if necessary, each component of other additives are mixed using a known method such as a mixer, and then kneaded to prepare a kneaded product. . The method of melt kneading is not particularly limited, and examples thereof include a method of melt kneading with a known kneader such as a mixing roll, a pressure kneader, or an extruder. The kneading conditions are not particularly limited as long as the temperature is equal to or higher than the softening point of each component described above. For example, 30 to 150 ° C., preferably 40 to 140 ° C., more preferably considering the thermosetting property of the epoxy resin. It is 60-120 degreeC, and time is 1 to 30 minutes, for example, Preferably it is 5 to 15 minutes. Thereby, a kneaded material can be prepared.

  The sealing resin sheet 11 can be obtained by molding the obtained kneaded material by extrusion molding. Specifically, the encapsulating resin sheet 11 can be formed by extrusion molding without cooling the kneaded product after melt-kneading while maintaining a high temperature state. Such an extrusion method is not particularly limited, and examples thereof include a T-die extrusion method, a roll rolling method, a roll kneading method, a co-extrusion method, and a calendar molding method. The extrusion temperature is not particularly limited as long as it is equal to or higher than the softening point of each component described above, but considering the thermosetting property and moldability of the epoxy resin, for example, 40 to 150 ° C, preferably 50 to 140 ° C, Preferably it is 70-120 degreeC. As described above, the sealing resin sheet 11 can be formed.

  The encapsulating resin sheet thus obtained may be used by being laminated so as to have a desired thickness if necessary. That is, the sealing resin sheet may be used in a single layer structure, or may be used as a laminate formed by laminating two or more multilayer structures.

Second Embodiment
Hereinafter, a second embodiment which is an embodiment of the present invention will be described. FIG. 3A to FIG. 3G are cross-sectional views schematically showing one process of a method for manufacturing a semiconductor package according to another embodiment of the present invention. In the first embodiment, the semiconductor chip flip-chip connected to the semiconductor wafer is resin-sealed with a sealing resin sheet. However, in the second embodiment, the semiconductor chip is temporarily fixed to a temporary fixing material instead of the semiconductor wafer. In this state, resin sealing is performed. The second embodiment is suitable for manufacturing a semiconductor package called a so-called Fan-out (fan-out) wafer level package (WLP).

[Temporary fixing material preparation process]
In the temporary fixing material preparing step, the temporary fixing material 2 in which the thermally expandable pressure-sensitive adhesive layer 2a is laminated on the support 2b is prepared (see FIG. 3A). In addition, it can replace with a thermally expansible adhesive layer, and can also use a radiation curing type adhesive layer. In the present embodiment, a temporary fixing material 2 including a thermally expandable pressure-sensitive adhesive layer will be described.

(Thermal expansion adhesive layer)
The heat-expandable pressure-sensitive adhesive layer 2a can be formed of a pressure-sensitive 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. Examples of the acrylic polymer A include those using (meth) acrylic acid ester as a main monomer component. Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl ester (for example, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, sec-butyl ester, t-butyl ester, Pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, Linear or branched alkyl ester having 1 to 30 carbon atoms, particularly 4 to 18 carbon atoms, of an alkyl group such as hexadecyl ester, octadecyl ester or eicosyl ester Le etc.) and (meth) acrylic acid cycloalkyl esters (e.g., cyclopentyl ester, cyclohexyl ester, etc.) and the like. These (meth) acrylic acid esters may be used alone or in combination of two or more.

  The acrylic polymer A corresponds to other monomer components that can be copolymerized with the (meth) acrylic acid ester, if necessary, for the purpose of modifying cohesive strength, heat resistance, crosslinkability, and the like. Units may be included. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and carboxyethyl acrylate; acid anhydrides such as maleic anhydride and itaconic anhydride Physical group-containing monomers; hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (N-substituted or unsubstituted) amide monomers such as N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; vinyl ester monomers such as vinyl acetate and vinyl propionate Styling Styrene monomers such as α-methylstyrene; vinyl ether monomers such as vinyl methyl ether and vinyl ethyl ether; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate Olefin or diene monomer such as ethylene, propylene, isoprene, butadiene and isobutylene; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, etc. (Substituted or unsubstituted) amino group-containing monomers; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; N-vinylpyrrolidone, N -Methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl oxazole, N-vinyl morpholine, N -Monomers having a nitrogen atom-containing ring such as vinyl caprolactam; N-vinylcarboxylic acid amides; Monomers containing sulfonic acid groups such as styrene sulfonic acid, allyl sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate A phosphate group-containing monomer such as 2-hydroxyethylacryloyl phosphate; a maleimide monomer such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; N Itacimide monomers such as methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide; N- ( Succinimide monomers such as (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide; polyethylene glycol (meth) acrylate, (meta ) Glycol acrylic ester monomers such as polypropylene glycol acrylate; Monomers having an oxygen atom-containing heterocycle such as tetrahydrofurfuryl (meth) acrylate; Fluorine Acrylic acid ester monomer containing fluorine atom such as (meth) acrylate; Acrylic acid ester monomer containing silicon atom such as silicone (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 tri (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, divinylbenzene, butyl di (meth) acrylate, hexyl And polyfunctional monomers such as di (meth) acrylate.

  The acrylic polymer A can be obtained by subjecting a single monomer or a mixture of two or more monomers to polymerization. The polymerization may be performed by any method such as solution polymerization (for example, radical polymerization, anionic polymerization, cationic polymerization), emulsion polymerization, bulk polymerization, suspension polymerization, photopolymerization (for example, ultraviolet (UV) polymerization). it can.

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

  In addition, an external cross-linking agent can be appropriately used for the heat-expandable pressure-sensitive adhesive in order to adjust the pressure-sensitive adhesive force. Specific examples of the external crosslinking method include a method of adding a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, a melamine crosslinking agent, and reacting them. When using an external cross-linking agent, the amount used is appropriately determined depending on the balance with the base polymer to be cross-linked, and further depending on the intended use as an adhesive. The amount of the external crosslinking agent used is generally 20 parts by weight or less (preferably 0.1 to 10 parts by weight) with respect to 100 parts by weight of the base polymer.

  As described above, the heat-expandable pressure-sensitive adhesive layer 2a contains a foaming agent for imparting heat-expandability. Therefore, in a state where the grinding body 26 including the semiconductor chip 23 ground on the thermally expandable pressure-sensitive adhesive layer 2a of the temporary fixing material 2 is formed (see FIG. 3C), the temporary fixing material 2 is at least partially attached at any time. And the foaming agent contained in the heated thermally expandable pressure-sensitive adhesive layer 2a is foamed and / or expanded, so that the heat-expandable pressure-sensitive adhesive layer 2a is at least partially expanded. Due to at least partial expansion of the thermally expandable pressure-sensitive adhesive layer 2a, the pressure-sensitive adhesive surface (interface with the grinding body 26) corresponding to the expanded portion is deformed into an uneven shape, and the heat-expandable pressure-sensitive adhesive layer 2a and The adhesion area with the grinding body 26 is reduced, whereby the adhesive force between the two is reduced, and the grinding body 26 can be peeled from the temporary fixing material 2 (see FIG. 3D).

(Foaming agent)
The foaming agent used in the thermally expandable pressure-sensitive adhesive layer 2a is not particularly limited, and can be appropriately selected from known foaming agents. A foaming agent can be used individually or in combination of 2 or more types. As the foaming agent, thermally expandable microspheres can be suitably used.

(Thermally expandable microsphere)
The heat-expandable microsphere is not particularly limited, and can be appropriately selected from known heat-expandable microspheres (such as various inorganic heat-expandable microspheres and organic heat-expandable microspheres). As the thermally expandable microspheres, a microencapsulated foaming agent can be suitably used from the viewpoint of easy mixing operation. Examples of such thermally expandable microspheres include microspheres in which substances such as isobutane, propane, and pentane that are easily gasified and expanded by heating are encapsulated in an elastic shell. The shell is often formed of a hot-melt material or a material that is destroyed by thermal expansion. Examples of the substance forming the shell include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

  Thermally expandable microspheres can be produced by a conventional method such as a coacervation method or an interfacial polymerization method. Examples of thermally expandable microspheres include, for example, a series of “Matsumoto Microsphere F30” and “Matsumoto Microsphere F301D” (trade names “Matsumoto Microsphere F30”, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.). "Matsumoto Microsphere F50D", "Matsumoto Microsphere F501D", "Matsumoto Microsphere F80SD", "Matsumoto Microsphere F80VSD", etc.) Commercially available products such as “051DU”, “053DU”, “551DU”, “551-20DU”, and “551-80DU” can be used.

  When thermally expandable microspheres are used as the foaming agent, the particle size (average particle diameter) of the thermally expandable microspheres can be appropriately selected according to the thickness of the thermally expandable pressure-sensitive adhesive layer. . The average particle diameter of the heat-expandable microspheres can be selected from a range of, for example, 100 μm or less (preferably 80 μm or less, more preferably 1 μm to 50 μm, particularly 1 μm to 30 μm). Note that the adjustment of the particle size of the thermally expandable microspheres may be performed in the process of generating the thermally expandable microspheres, or may be performed by means such as classification after the generation. It is preferable that the thermally expandable microspheres have the same particle size.

(Other foaming agents)
In the present embodiment, as the foaming agent, a foaming agent other than the thermally expandable microsphere can also be used. As such a foaming agent, various foaming agents such as various inorganic foaming agents and organic foaming agents can be appropriately selected and used. Typical examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, various azides and the like.

  Representative examples of organic foaming agents include, for example, water; chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodicarbonamide, and barium azodi. Azo compounds such as carboxylate; hydrazine compounds such as p-toluenesulfonyl hydrazide, diphenylsulfone-3,3'-disulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide); p- Semicarbazide compounds such as toluylenesulfonyl semicarbazide and 4,4′-oxybis (benzenesulfonyl semicarbazide); Triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N, N′-dinitrosopene Methylene terrorism Ramin, N, N'-dimethyl -N, N'N-nitroso compounds such as dinitrosoterephthalamide, and the like.

  In this embodiment, in order to reduce the adhesive force of the heat-expandable pressure-sensitive adhesive layer efficiently and stably by heat treatment, the volume expansion coefficient is 5 times or more, especially 7 times or more, particularly 10 times or more. A foaming agent having an appropriate strength that does not burst is preferred.

  The amount of foaming agent (thermally expandable microspheres, etc.) can be set as appropriate depending on the expansion ratio of the thermally expandable pressure-sensitive adhesive layer and the ability to lower the adhesive strength, but generally a thermally expandable pressure-sensitive adhesive layer is formed. The amount is, 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) with respect to 100 parts by weight of the base polymer.

In this embodiment, a foaming agent having a foaming start temperature (thermal expansion start temperature) (T ₀ ) in the range of 80 ° C. to 210 ° C. can be suitably used, and preferably 90 ° C. to 200 ° C. (more Preferably, it has a foaming start temperature of 95 ° C to 200 ° C, particularly preferably 100 ° C to 170 ° C. When the foaming start temperature of the foaming agent is lower than 80 ° C., the foaming agent may foam due to heat during production or use of the sealing body or the grinding body, and handling properties and productivity are lowered. On the other hand, when the foaming start temperature of the foaming agent exceeds 210 ° C., excessive heat resistance is required for the support of the temporary fixing material and the sealing resin, which is not preferable in terms of handleability, productivity, and cost. Incidentally, the foaming starting temperature (T ₀₎ of the blowing agent, corresponding to the foaming starting temperature of the heat-expandable pressure-sensitive adhesive layer (T _0).

  In addition, as a method of foaming the foaming agent (that is, a method of thermally expanding the heat-expandable pressure-sensitive adhesive layer), it can be appropriately selected from known heat foaming methods.

In the present embodiment, the heat-expandable pressure-sensitive adhesive layer has an elastic modulus of 23 ° C. in a form not containing a foaming agent from the viewpoint of a balance between moderate adhesive force before heat treatment and lowering of adhesive force after heat treatment. It is preferably 5 × 10 ⁴ Pa to 1 × 10 ⁶ Pa at ˜150 ° C., more preferably 5 × 10 ⁴ Pa to 8 × 10 ⁵ Pa, and particularly 5 × 10 ⁴ Pa to ⁵ × 10 ⁵ Pa. It is preferable that When the elastic modulus (temperature: 23 ° C. to 150 ° C.) of the thermally expandable pressure-sensitive adhesive layer in a form not containing a foaming agent is less than 5 × 10 ⁴ Pa, the thermal expandability may be inferior and the peelability may decrease. . Moreover, when the elasticity modulus (temperature: 23 degreeC-150 degreeC) in the form which does not contain the foaming agent of a thermally expansible adhesive layer is larger than 1 * 10 < ⁶ > Pa, initial stage adhesiveness may be inferior.

In addition, the thermally expansible adhesive layer of the form which does not contain a foaming agent is corresponded to the adhesive layer formed with the adhesive (The foaming agent is not contained). Therefore, the elastic modulus of the thermally expandable pressure-sensitive adhesive layer in a form not containing a foaming agent can be measured using a pressure-sensitive adhesive (no foaming agent is included). In addition, a thermal expansion adhesive layer is a thermal expansion containing the adhesive which can form the adhesive layer whose elasticity modulus in 23 degreeC-150 degreeC is 5 * 10 < ⁴ > Pa-1 * 10 < ⁶ > Pa, and a foaming agent. It can be formed with an adhesive.

  The modulus of elasticity of the thermally expandable pressure-sensitive adhesive layer in the form not containing the foaming agent is the heat-expandable pressure-sensitive adhesive layer in the form in which the foaming agent is not added (that is, the pressure-sensitive adhesive layer by the pressure-sensitive adhesive not containing the foaming agent). ) (Sample), using a rheometric dynamic viscoelasticity measuring device “ARES”, sample thickness: about 1.5 mm, φ7.9 mm parallel plate jig, in shear mode , Frequency: 1 Hz, rate of temperature increase: 5 ° C./min, strain: 0.1% (23 ° C.), 0.3% (150 ° C.) measured at 23 ° C. and 150 ° C. shear storage elasticity obtained The value of the rate G ′ is assumed.

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

  The thickness of the heat-expandable pressure-sensitive adhesive layer is not particularly limited, and can be appropriately selected depending on the reduction in adhesive strength, and is, for example, about 5 μm to 300 μm (preferably 20 μm to 150 μm). However, when heat-expandable microspheres are used as the foaming agent, the thickness of the heat-expandable pressure-sensitive adhesive layer is preferably thicker than the maximum particle size of the heat-expandable microspheres contained. When the thickness of the heat-expandable pressure-sensitive adhesive layer is too thin, the surface smoothness is impaired by the unevenness of the heat-expandable microspheres, and the adhesiveness before heating (unfoamed state) is lowered. In addition, the degree of deformation of the heat-expandable pressure-sensitive adhesive layer by heat treatment is small, and the adhesive force is not easily lowered. On the other hand, if the thickness of the heat-expandable pressure-sensitive adhesive layer is too thick, cohesive failure is likely to occur in the heat-expandable pressure-sensitive adhesive layer after expansion or foaming by heat treatment, and adhesive residue may be generated in the grinding body 26. .

  The thermally expandable pressure-sensitive adhesive layer may be either a single layer or multiple layers.

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

(Support)
The support 2b is a thin plate member that serves as a strength matrix of the temporary fixing material 2. The material of the support 2b may be appropriately selected in consideration of handling properties, heat resistance, and the like. For example, metal materials such as SUS, plastic materials such as polyimide, polyamideimide, polyether ether ketone, and polyether sulfone, glass Alternatively, a silicon wafer or the like can be used. Among these, a SUS plate is preferable from the viewpoints of heat resistance, strength, reusability, and the like.

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

(Method for forming temporary fixing material)
The temporary fixing material 2 is obtained by forming the thermally expandable pressure-sensitive adhesive layer 2a on the support 2b. The heat-expandable pressure-sensitive adhesive layer is formed into a sheet-like layer by mixing, for example, a pressure-sensitive adhesive, a foaming agent (such as heat-expandable microspheres), and a solvent or other additives as necessary. It can be formed using conventional methods. Specifically, for example, a method of applying a mixture containing an adhesive, a foaming agent (such as thermally expandable microspheres), and, if necessary, a solvent and other additives onto the support 2b, an appropriate separator ( The heat-expandable pressure-sensitive adhesive layer can be formed by applying the mixture on a release paper or the like to form a heat-expandable pressure-sensitive adhesive layer and transferring (transferring) it onto the support 2b. it can.

(Thermal expansion method of the thermally expandable pressure-sensitive adhesive layer)
In the present embodiment, the thermally expandable pressure-sensitive adhesive layer can be thermally expanded by heating. As the heat treatment method, for example, an appropriate heating means such as a hot plate, a hot air dryer, a near infrared lamp, an air dryer or the like can be used. The heating temperature during the heat treatment may be equal to or higher than the foaming start temperature (thermal expansion start temperature) of the foaming agent (thermally expansible microspheres, etc.) in the heat-expandable pressure-sensitive adhesive layer. It can be set as appropriate depending on the reduction of the adhesion area depending on the type of agent (thermally expandable microspheres, etc.), the heat resistance of a support, a grinding body including a semiconductor chip, etc., the heating method (heat capacity, heating means, etc.), and the like. As general heat treatment conditions, the temperature is 100 ° C. to 250 ° C., and it is 1 second to 90 seconds (hot plate or the like) or 5 minutes to 15 minutes (hot air dryer or the like). Note that the heat treatment can be performed at an appropriate stage depending on the purpose of use. In some cases, an infrared lamp or heated water can be used as the heat source during the heat treatment.

(Middle layer)
In the present embodiment, an intermediate layer may be provided between the heat-expandable pressure-sensitive adhesive layer 2a and the support 2b for the purpose of improving adhesion and improving peelability after heating (not shown). ) Among them, it is preferable that a rubbery organic elastic intermediate layer is provided as the intermediate layer. Thus, by providing the rubber-like organic elastic intermediate layer, when the semiconductor chip 23 is bonded to the temporary fixing material 2 (see FIG. 3A), the surface of the thermally expandable pressure-sensitive adhesive layer 2a is changed to the surface shape of the semiconductor chip 23. The adhesion area can be increased, and the thermal expansion of the thermally expandable pressure-sensitive adhesive layer 2a is highly enhanced when the grinding body 26 after grinding is thermally peeled from the temporary fixing material 2 (see FIG. The heat-expandable pressure-sensitive adhesive layer 2a can be preferentially and uniformly expanded in the thickness direction.

  The rubbery organic elastic intermediate layer can be interposed on one side or both sides of the support 2b.

  The rubber-like organic elastic intermediate layer is preferably formed of natural rubber, synthetic rubber, or synthetic resin having rubber elasticity having a D-type Sure D-type hardness of 50 or less, particularly 40 or less based on ASTM D-2240. Even if it is essentially a hard polymer such as polyvinyl chloride, rubber elasticity can be manifested in combination with compounding agents such as plasticizers and softeners. Such a composition can also be used as a constituent material of the rubbery organic elastic intermediate layer.

  The rubber-like organic elastic intermediate layer is, for example, a method (coating method) in which a coating liquid containing a rubber-like organic elastic layer forming material such as natural rubber, synthetic rubber, or synthetic resin having rubber elasticity is applied onto a substrate, A method in which a film made of a rubbery organic elastic layer forming material or a laminated film in which a layer made of the rubbery organic elastic layer forming material is previously formed on one or more thermally expandable pressure-sensitive adhesive layers is bonded to a substrate (dry Laminating method), and a forming method such as a method of co-extruding a resin composition containing a constituent material of a base material and a resin composition containing the rubber-like organic elastic layer forming material (co-extrusion method).

  The rubbery organic elastic intermediate layer may be formed of a sticky substance mainly composed of natural rubber, synthetic rubber, or synthetic resin having rubber elasticity, and may be a foam film or the like mainly composed of such a component. It may be formed. Foaming is a conventional method, for example, a method using mechanical stirring, a method using a reaction product gas, a method using a foaming agent, a method for removing soluble substances, a method using a spray, a method for forming a syntactic foam, It can be performed by a sintering method or the like.

  The thickness of the intermediate layer such as the rubbery organic elastic intermediate layer is, for example, about 5 μm to 300 μm, preferably about 20 μm to 150 μm. In addition, when the intermediate layer is, for example, a rubber-like organic elastic intermediate layer, if the thickness of the rubber-like organic elastic intermediate layer is too thin, it is not possible to form a three-dimensional structural change after heating and foaming. Sexuality may worsen.

  The intermediate layer such as the rubbery organic elastic intermediate layer may be a single layer or may be composed of two or more layers.

  In the intermediate layer, various additives (for example, a colorant, a thickener, an extender, a filler, a tackifier, a plasticizer, an anti-aging agent, an oxidation agent, etc.) An inhibitor, a surfactant, a cross-linking agent, etc.).

(Semiconductor chip placement process)
In the semiconductor chip arrangement step, a plurality of semiconductor chips 23 are arranged on the temporary fixing material 2 such that the active surface A2 faces the temporary fixing material 2 (see FIG. 3A). A known device such as a flip chip bonder or a die bonder can be used for arranging the semiconductor chip 23.

  The layout and the number of arrangement of the semiconductor chips 23 can be appropriately set according to the shape and size of the temporary fixing material 2, the number of target packages produced, and the like, for example, a matrix of a plurality of rows and a plurality of columns. Can be arranged in a line.

(Sealing process)
In the sealing step, the sealing resin sheet 21 is laminated on the temporary fixing material 2 so as to cover the plurality of semiconductor chips 23 and is resin-sealed (see FIG. 3B). The same conditions as in the first embodiment can be adopted for the method of laminating the sealing resin sheet 21 on the temporary fixing material 2.

(Sealing body forming process)
In the sealing body forming step, the sealing resin sheet 21 is subjected to a thermosetting process to form the sealing body 25 (see FIG. 3B). The conditions for the thermosetting treatment of the sealing resin sheet 21 can employ the same conditions as in the first embodiment.

(Grinding process)
In the grinding step, the sealing resin sheet 21 of the sealing body 25 is ground so that the surface 23S opposite to the active surface A2 of the semiconductor chip 23 is exposed to form the grinding body 26 (see FIG. 3C). Grinding may be performed using a known grinding apparatus.

  The maximum height difference between the surface 21S of the sealing resin sheet and the exposed surface 23S of the semiconductor chip in the grinding body 26 is 10 μm or less, preferably 7 μm or less, more preferably 5 μm or less. By setting the maximum height difference on the grinding surface G2 (see FIG. 3E) within the above range, the influence of the step on the grinding surface G2 of the grinding body 26 on the back surface B2 can be reduced, and the rewiring 29 is formed with high yield. be able to.

(Thermal expansion adhesive layer peeling process)
In the heat-expandable pressure-sensitive adhesive layer peeling step, the temporary fixing material 2 is heated to thermally expand the heat-expandable pressure-sensitive adhesive layer 2a, whereby peeling is performed between the heat-expandable pressure-sensitive adhesive layer 2a and the grinding body 26. (See FIG. 3D). Alternatively, a procedure of peeling at the interface between the support 2b and the heat-expandable pressure-sensitive adhesive layer 2a and then peeling at the interface between the heat-expandable pressure-sensitive adhesive layer 2a and the grinding body 26 is preferably employed. can do. In either case, the heat-expandable pressure-sensitive adhesive layer 2a is heated and thermally expanded to reduce the adhesive force, thereby easily peeling at the interface between the heat-expandable pressure-sensitive adhesive layer 2a and the grinding body 26. It can be carried out. As the conditions for thermal expansion, the conditions in the above-mentioned column “Thermal expansion method for thermally expandable pressure-sensitive adhesive layer” can be preferably employed.

  In this step, the surface of the grinding body 26 may be cleaned by plasma treatment or the like prior to the rewiring forming step with the semiconductor chip 23 exposed.

(Rewiring process)
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 chip 23 of the grinding body 26. In the rewiring forming step, after the thermally expandable pressure-sensitive adhesive layer 2a is peeled off, a rewiring 29 connected to the exposed semiconductor chip 23 is formed on the grinding body 26 (see FIG. 3E).

  As a method of forming the rewiring, for example, a metal seed layer is formed on the exposed semiconductor chip 23 using a known method such as a vacuum film forming method, and then re-reformed by a known method such as a semi-additive method. The wiring 29 can be formed.

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

(Bump formation process)
Next, a bumping process for forming bumps 27 on the formed rewiring 29 may be performed (see FIG. 3F). The bumping process can be performed by a known method such as a solder ball or solder plating. As the material of the bump 27, the same material as that of the first embodiment can be suitably used.

(Chip back surface protection process)
After the bumps 27 are formed, the ground surface G2 (see FIG. 3C) of the ground body 26A may be resin-sealed again in order to protect the exposed surface 23S of the semiconductor chip 23. The sealing method is not particularly limited, and a known liquid or film-like sealing resin may be applied or bonded to the grinding surface G2, dried, and cured. This step may be performed at any stage after the grinding step and before the dicing step.

(Dicing process)
Finally, dicing is performed on the laminate including elements such as the semiconductor chip 23, the sealing resin sheet 21, and the rewiring 29 (see FIG. 3G). Thereby, the semiconductor package 28 in which the wiring is drawn outside the chip region can be obtained in units of semiconductor chips. As the dicing method, the same method as in the first embodiment can be adopted.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in this example are not intended to limit the scope of the present invention only to those unless otherwise specified. The term “parts” means parts by weight.

[Example 1]
(Preparation of sealing resin sheet)
The following components were blended with a mixer, melt kneaded at 120 ° C. for 2 minutes with a twin-screw kneader, and then extruded from a T-die to prepare a sealing resin sheet A 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.)) 286 parts Phenol resin: phenol resin having biphenylaralkyl skeleton (Maywa Kasei Co., Ltd.) Manufactured by MEH-7851-SS (hydroxyl equivalent: 203 g / eq., Softening point: 67 ° C.))
303 parts Curing accelerator: Imidazole-based catalyst as a curing catalyst (manufactured by Shikoku Chemicals Co., Ltd., 2PHZ-PW) 6 parts Inorganic filler: Spherical fused silica powder (manufactured by Denki Kagaku Kogyo, FB-9454, average particle size) 3695 parts Silane coupling agent: Epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) 5 parts Carbon black (manufactured by Mitsubishi Chemical Corporation, # 20) 5 parts

[Example 2]
(Preparation of sealing resin sheet)
The following components were blended with a mixer, melt-kneaded at 120 ° C. for 2 minutes with a twin-screw kneader, and then extruded from a T die to prepare 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 Phenol resin: phenol resin having biphenylaralkyl skeleton (Maywa Kasei Co., Ltd.) Manufactured by MEH-7851-SS (hydroxyl equivalent: 203 g / eq., Softening point: 67 ° C.))
179 parts Curing accelerator: Imidazole-based catalyst as a curing catalyst (manufactured by Shikoku Chemicals Co., Ltd., 2PHZ-PW) 6 parts Elastomer: Styrene-isobutylene-styrene triblock copolymer (manufactured by Kaneka Corporation, SIBSTAR 072T) 152 parts Inorganic filler: spherical fused silica powder (manufactured by Denki Kagaku Kogyo Co., Ltd., FB-9454, average particle size 20 μm) 1100 parts Silane coupling agent: epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM) -403) 5 parts Carbon black (Mitsubishi Chemical Corporation, # 20) 5 parts Flame retardant: Phosphazene compound (FP-100, Fushimi Pharmaceutical Co., Ltd.) 89 parts

[Comparative Example 1]
(Preparation of sealing resin sheet)
The following components were dissolved or dispersed in methyl ethyl ketone to prepare a varnish having a solid content of 40% by weight.

Liquid epoxy resin (Dai Nippon Ink Chemical Co., Ltd., EXA-4850-150)
80 parts Solid epoxy resin (Nippon Kayaku Co., Ltd., EPPN-501-HY) 20 parts Phenol resin: Phenol resin having biphenylaralkyl skeleton (Maywa Kasei Co., Ltd., MEH-7851-SS (hydroxyl equivalent: 203 g / eq. , Softening point 67 ℃))
60 parts Curing accelerator: Imidazole catalyst as a curing catalyst (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2PHZ-PW) 3 parts Acrylic copolymer (*) 330 parts Inorganic filler: Spherical fused silica powder (Electrochemical Co., Ltd.) FB-9454, average particle size 20 μm) 400 parts Carbon black (Mitsubishi Chemical Corporation, # 20) 7 parts

  The acrylic copolymer (*) is a copolymer comprising BA (butyl acrylate): AN (acrylonitrile): GMA (glycidyl methacrylate) = 85: 8: 7% by weight, and the weight average molecular weight is 80. Ten thousand. The acrylic copolymer was synthesized as follows. Butyl acrylate, acrylonitrile, glycidyl methacrylate in a weight ratio of 85: 8: 7, using 2,2′-azobisisobutyronitrile as a polymerization initiator in methyl ethyl ketone at 70 ° C. for 5 hours under a nitrogen stream Radical polymerization at 80 ° C. for 1 hour to obtain the desired acrylic copolymer.

  On the PET film subjected to the mold release treatment, the varnish was applied so that the thickness of the coating film after drying the solvent was 50 μm, and then the drying film was dried at 120 ° C. for 3 minutes to dry the coating film. A resin sheet having a thickness of 50 μm was obtained. The obtained resin sheet was laminated | stacked to thickness of 500 micrometers using the laminator, and the sealing resin sheet C was produced.

(Measurement of storage elastic modulus of sealing resin sheet)
The storage elastic modulus was measured using a solid viscoelasticity measuring apparatus (manufactured by Rheometric Scientific: model: RSA-III). Specifically, each sealing resin sheet is heated and cured at 150 ° C. for 1 hour, and a measurement sample is obtained from the cured product with a sample size of 400 mm long × 2 mm wide × 80 μm thick, and then the measurement sample. Is measured in a film tension measuring jig, and the storage elastic modulus and loss elastic modulus in the temperature range of −50 to 300 ° C. are measured under the conditions of a frequency of 1 Hz, a heating rate of 10 ° C./min, and a strain of 0.05%. And the storage elastic modulus (E ′) at 25 ° C. was read.

(Measurement of Shore D hardness of encapsulating resin sheet)
Each sealing resin sheet was laminated using a laminator so as to have a thickness of 2 mm, and this laminate was heated at 150 ° C. for 1 hour to be thermally cured, and in accordance with JIS K 7215, a hardness meter (Corporation) It was obtained by reading the measured value at 25 ° C. using a Mitutoyo plastic hardness tester.

(Production of semiconductor package)
A chip mounting interposer was prepared in which a semiconductor chip having the following specifications was flip-chip mounted on a silicon interposer, and the space between the chip and the interposer was sealed with a bisphenol A type epoxy thermosetting underfill material.

<Semiconductor chip>
Semiconductor chip size: 7.3 mm □ (thickness 400 μm)
Bump material: Cu 30 μm, Sn-Ag 15 μm thickness Number of bumps: 544 bumps Bump pitch: 50 μm
Number of chips: 16 (4 x 4)

<Silicon interposer>
Diameter: 8 inches Thickness: 730 μm
Electrode: Through silicon via (diameter: 30 μm)

  On the obtained chip mounting interposer, each of the sealing resin sheets A to C was pasted by a vacuum press under the heating and pressing conditions shown below.

<Paste conditions>
Temperature: 90 ° C
Applied pressure: 0.5 MPa
Degree of vacuum: 2000Pa
Press time: 3 minutes

  After releasing to atmospheric pressure, the sealing resin sheet was thermoset in a hot air dryer at 150 ° C. for 1 hour to obtain a sealing body. Next, the thickness of the semiconductor chip is obtained by grinding using a cutting device (manufactured by DISCO Corporation, surface planar “DFS8910”) under the conditions of a peripheral speed of the grinding tool of 1000 m / min, a feed pitch of 100 μm, and a cutting depth of 10 μm. By grinding the sealing body together with the semiconductor chip until the thickness becomes 100 μm, a ground body was produced.

  The exposed surface of the silicon interposer (the surface opposite to the surface on which the sealing resin sheet is bonded) of the obtained grinding body is removed by a grinding device (“DGP8761” manufactured by DISCO) and the thickness of the silicon interposer is 100 μm. Grinded until

  Apply polyamic acid (obtained by reacting 3,4 ', 3,4'-biphenyltetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether, paraphenylenediamine) to the ground surface of the silicon interposer. Then, a polyimide layer having a thickness of 10 μm was formed by thermosetting. An opening was formed by laser processing at a position corresponding to the through-silicon via to expose the via. A gold film and a nickel film were sequentially formed on the surface of the polyimide layer including the opening by plating. Further, sputtering is performed in the order of chromium and copper to form a seed film (chrome layer thickness 20 nm, copper layer thickness 100 nm), and a rewiring layer having a predetermined wiring pattern is formed by electrolytic copper plating. Thus, a semiconductor package was produced.

(Measurement of maximum height difference of ground surface)
Using the semiconductor package of Example and Comparative Example, the surface of the sealing resin sheet and the exposed surface of the semiconductor chip on the ground surface of the semiconductor package using a stylus type surface shape measuring instrument (“Dektak 8”, ULVAC, Inc.) The maximum height difference was measured. Specifically, as shown in FIG. 4, the surface shape of the grinding surface is obtained by scanning the surface once for every row and every column so as to include each row and each column of the semiconductor chips 13 arranged in a matrix. The maximum height difference was calculated based on this surface shape. Further, on the rewiring formation surface, whether or not there was a break in the wiring was confirmed with a microscope (magnification: 500 times). The results are shown in Table 1.

  As is clear from Table 1, in Examples 1 and 2, the maximum height difference after grinding is 10 μm or less, so that rewiring can be formed as a circuit surface element of a semiconductor package with a high yield. On the other hand, in the semiconductor package of Comparative Example 1, the maximum height difference exceeded 10 μm, resulting in poor rewiring formability.

11, 21 Encapsulating resin sheet 11S, 21S Surface of encapsulating resin sheet (after grinding) 12A (Before grinding) Semiconductor wafer 12B (After grinding) Semiconductor wafer 13, 23 Semiconductor chip 13S, 23S (After grinding) Exposed surface of semiconductor chip 15, 25 Sealing body 16A, 16B, 16C, 26 Grinding body 18, 28 Semiconductor package 19, 29 Rewiring

Claims (7)

A sealing body forming step of forming a sealing body in which one or a plurality of semiconductor chips are embedded in a sealing resin sheet; and the sealing resin sheet of the sealing body on a side opposite to an active surface of the semiconductor chip. Grinding process to form a grinding body by grinding so that the surface is exposed,
The manufacturing method of the semiconductor package whose maximum height difference of the surface of the said sealing resin sheet in the said grinding body and the exposed surface of the said semiconductor chip is 10 micrometers or less.   2. The method of manufacturing a semiconductor package according to claim 1, wherein the Shore D hardness at 25 ° C. of the encapsulating resin sheet after performing a thermosetting treatment at 150 ° C. for 1 hour is 60 or more.   3. The method for manufacturing a semiconductor package according to claim 1, wherein a storage elastic modulus at 25 ° C. of the encapsulating resin sheet after performing a thermosetting treatment at 150 ° C. for 1 hour is 3 GPa or more.   The semiconductor package according to any one of claims 1 to 3, wherein, in the sealing body forming step, the sealing body is formed by embedding the semiconductor chip flip-chip connected to a semiconductor wafer in the sealing resin sheet. Manufacturing method.   The semiconductor package according to any one of claims 1 to 3, wherein, in the sealing body forming step, the sealing body is formed by embedding the semiconductor chip fixed to a temporary fixing material in the sealing resin sheet. Production method.   6. The method of manufacturing a semiconductor package according to claim 1, further comprising a rewiring forming step of forming a rewiring on a surface on an active surface side of the semiconductor chip of the ground body after the grinding step. A plurality of the semiconductor chips are used,
The semiconductor package manufacturing method according to claim 6, further comprising a dicing step of dicing the ground body in units of a target semiconductor chip after the rewiring forming step.

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