JP2013115185A - Manufacturing method for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a semiconductor device capable of manufacturing a highly-reliable semiconductor device by suppressing void when a semiconductor element is mounted.SOLUTION: A manufacturing method for a semiconductor device provided with an adherend, a semiconductor element electrically connected to the adherend, and an underfill material which fills a space between the adherend and the semiconductor element comprises the steps of: preparing a sealing sheet provided with a base material and an underfill material laminated on the base material; sticking the sealing sheet to a surface on which a connection member of a semiconductor wafer is formed; forming a semiconductor element with the underfill material by dicing the semiconductor wafer; holding the semiconductor element with the underfill material at 100 to 200°C for over a second; and electrically connecting the semiconductor element and the adherend via the connection member while filling the space between the adherend and the semiconductor element with the underfill material.

Description

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

  In recent years, the demand for high-density packaging due to the miniaturization and thinning of electronic devices has increased rapidly. For this reason, the surface mount type suitable for high-density mounting is the mainstream of the semiconductor package instead of the conventional pin insertion type. In this surface mount type, the lead is soldered directly to a printed circuit board or the like. As a heating method, the entire package is heated and mounted by infrared reflow, vapor phase reflow, solder dipping, or the like.

  After the surface mounting, the space between the semiconductor element and the substrate is filled with a sealing resin in order to protect the surface of the semiconductor element and to ensure the connection reliability between the semiconductor element and the substrate. As such a sealing resin, although a liquid sealing resin is widely used, it is difficult to adjust the injection position and the injection amount with the liquid sealing resin. Therefore, a technique for filling a space between a semiconductor element and a substrate using a sheet-shaped sealing resin has also been proposed (Patent Document 1).

  In general, as a process using a sheet-shaped sealing resin, after a sheet-shaped sealing resin is attached to a semiconductor wafer, the semiconductor element is diced to form a semiconductor element. A procedure of filling a space between an adherend such as a substrate and the semiconductor element with a sheet-like sealing resin integrated with the semiconductor element while being connected to the semiconductor element is employed.

Patent No. 4438973

  However, although the above process facilitates filling between the adherend and the semiconductor element, voids (bubbles) are generated in the sealing resin when the semiconductor element is mounted at a high temperature, thereby protecting the surface of the semiconductor element and protecting the semiconductor element and the semiconductor element. There is a risk that connection reliability with the kimono will be insufficient.

  An object of the present invention is to provide a method of manufacturing a semiconductor device that can suppress a void at the time of mounting a semiconductor element and can manufacture a highly reliable semiconductor device.

  The inventors of the present application made extensive studies and obtained the following findings. The sheet-shaped sealing resin has undergone a dicing process before mounting the semiconductor element. In the dicing process, water may be used for heat dissipation and cleaning during dicing. It has been found that water during the dicing and moisture in the air are absorbed by the sheet-shaped sealing resin, and the absorbed moisture evaporates and expands due to heating during mounting to generate voids. Based on this knowledge, the inventors of the present application have found that the object can be achieved by adopting the following configuration, and have completed the present invention.

That is, the present invention relates to a semiconductor device including an adherend, a semiconductor element electrically connected to the adherend, and an underfill material that fills a space between the adherend and the semiconductor element. A manufacturing method comprising:
Preparing a sealing sheet comprising a substrate and an underfill material laminated on the substrate;
Bonding the sealing sheet to the surface on which the connecting member of the semiconductor wafer is formed;
Forming a semiconductor element with the underfill material by dicing the semiconductor wafer;
Holding the semiconductor element with the underfill material at 100 to 200 ° C. for 1 second or more;
Electrically connecting the semiconductor element and the adherend via the connecting member while filling a space between the adherend and the semiconductor element with an underfill material.

  According to the manufacturing method, since the step of holding the semiconductor element with the underfill material at 100 to 200 ° C. for 1 second or longer is provided before connecting the semiconductor element and the adherend, the moisture in the underfill material As a result, it is possible to manufacture a highly reliable semiconductor device by suppressing the generation of voids when the semiconductor element is mounted.

  In the said manufacturing method, it is preferable that the minimum melt viscosity in 100-200 degreeC of the said underfill material before thermosetting is 100 Pa.s or more and 20000 Pa.s or less. Thereby, the approach to the underfill material of a connection member can be made easy. In addition, generation of voids during electrical connection of the semiconductor elements and protrusion of the underfill material from the space between the semiconductor elements and the adherend can be prevented. In addition, the measurement of minimum melt viscosity is based on the procedure as described in an Example.

  In the manufacturing method, the viscosity of the underfill material before thermosetting at 23 ° C. is preferably 0.01 MPa · s or more and 100 MPa · s or less. When the underfill material before thermosetting has such a viscosity, the retention property of the semiconductor wafer during dicing and the handleability during work can be improved.

  In the manufacturing method, the water absorption rate under the conditions of the temperature of 23 ° C. and the humidity of 70% of the underfill material before thermosetting is preferably 1% by weight or less. When the underfill material has such a water absorption rate, absorption of moisture into the underfill material is suppressed, and generation of voids during mounting of the semiconductor element can be more efficiently suppressed.

It is a cross-sectional schematic diagram which shows the sealing sheet which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the semiconductor device which concerns on one Embodiment of this invention.

  The present invention relates to a method of manufacturing a semiconductor device comprising an adherend, a semiconductor element electrically connected to the adherend, and an underfill material that fills a space between the adherend and the semiconductor element. A step of preparing a sealing sheet comprising a base material and an underfill material laminated on the base material, and a step of bonding the sealing sheet to the surface on which the connecting member of the semiconductor wafer is formed. , A step of dicing the semiconductor wafer to form a semiconductor element with the underfill material, a step of holding the semiconductor element with the underfill material at 100 to 200 ° C. for 1 second or more, the adherend and the above A step of electrically connecting the semiconductor element and the adherend via the connecting member while filling a space between the semiconductor elements with an underfill material. Hereinafter, an embodiment of the present invention will be described.

[Encapsulation sheet preparation process]
In the sealing sheet preparation step, a sealing sheet including a base material and an underfill material laminated on the base material is prepared.

(Sealing sheet)
As shown in FIG. 1, the sealing sheet 10 includes a base material 1 and an underfill material 2 laminated on the base material 1. Note that the underfill material 2 does not have to be laminated on the entire surface of the base material 1 and only needs to be provided in a size sufficient for bonding with the semiconductor wafer.

(Base material)
The base material 1 is a strength matrix of the sealing sheet 10. Examples of the material for forming the substrate 1 include low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolyprolene, polybutene, poly Polyolefins such as methylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer Polymers, ethylene-hexene copolymers, polyesters such as polyurethane, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyetheretherketone, polyimide, polyetherimide, polyamide, wholly aromatic poly Bromide, polyphenyl sulfide, aramid (paper), glass, glass cloth, fluorine resin, polyvinyl chloride, polyvinylidene chloride, cellulose resin, silicone resin, metal (foil), and paper such as glassine paper.

  Examples of the material of the base material 1 include polymers such as cross-linked resins of the resins listed above. The plastic film may be used unstretched or may be uniaxially or biaxially stretched as necessary. According to the sealing sheet to which heat shrinkability is imparted by stretching treatment or the like, the adhesive area between the base material 1 and the underfill material 2 is reduced by thermally shrinking the base material 1 after dicing, and the semiconductor chip is recovered. Can be facilitated.

  The surface of the substrate 1 is chemically treated by conventional surface treatments such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, ionizing radiation treatment, etc., in order to improve adhesion and retention with adjacent layers. Alternatively, a physical treatment or a coating treatment with a primer (for example, an adhesive substance described later) can be performed.

  The base material 1 can be used by appropriately selecting the same kind or different kinds, and a blend of several kinds can be used as necessary. In addition, the base material 1 is provided with a deposited layer of a conductive material having a thickness of about 30 to 500 mm made of a metal, an alloy, an oxide thereof, or the like on the base material 1 in order to impart an antistatic ability. be able to. The substrate 1 may be a single layer or two or more types.

  The thickness of the substrate 1 is not particularly limited and can be appropriately determined, but is generally about 5 to 200 μm.

(Underfill material)
The underfill material 2 in the present embodiment can be used as a sealing film that fills a space between a surface-mounted semiconductor element and an adherend. As a constituent material of the underfill material, a combination of a thermoplastic resin and a thermosetting resin can be used. A thermoplastic resin or a thermosetting resin alone can also be used.

  Examples of the thermoplastic resin include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, heat Examples thereof include plastic polyimide resins, polyamide resins such as 6-nylon and 6,6-nylon, phenoxy resins, acrylic resins, saturated polyester resins such as PET and PBT, polyamideimide resins, and fluorine resins. These thermoplastic resins can be used alone or in combination of two or more. Of these thermoplastic resins, an acrylic resin that has few ionic impurities and high heat resistance and can ensure the reliability of the semiconductor element is particularly preferable.

  The acrylic resin is not particularly limited, and includes one or two or more esters of acrylic acid or methacrylic acid having a linear or branched alkyl group having 30 or less carbon atoms, particularly 4 to 18 carbon atoms. Examples include polymers as components. Examples of the alkyl group include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, heptyl group, cyclohexyl group, 2 -Ethylhexyl group, octyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, lauryl group, tridecyl group, tetradecyl group, stearyl group, octadecyl group, dodecyl group and the like.

  In addition, the other monomer forming the polymer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Carboxyl group-containing monomers such as acid anhydride monomers such as maleic anhydride or itaconic anhydride, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4- (meth) acrylic acid 4- Hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate or (4-hydroxymethylcyclohexyl) -Methyla Hydroxyl group-containing monomers such as relate, styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate or (meth) Examples thereof include sulfonic acid group-containing monomers such as acryloyloxynaphthalene sulfonic acid, and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

  Examples of the thermosetting resin include phenol resin, amino resin, unsaturated polyester resin, epoxy resin, polyurethane resin, silicone resin, and thermosetting polyimide resin. These resins can be used alone or in combination of two or more. In particular, an epoxy resin containing a small amount of ionic impurities or the like that corrode semiconductor elements is preferable. Moreover, as a hardening | curing agent of an epoxy resin, a phenol resin is preferable.

  The epoxy resin is not particularly limited as long as it is generally used as an adhesive composition, for example, bisphenol A type, bisphenol F type, bisphenol S type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol AF type. Biphenyl type, naphthalene type, fluorene type, phenol novolac type, orthocresol novolak type, trishydroxyphenylmethane type, tetraphenylolethane type, etc., bifunctional epoxy resin or polyfunctional epoxy resin, or hydantoin type, trisglycidyl isocyanurate Type or glycidylamine type epoxy resin is used. These can be used alone or in combination of two or more. Of these epoxy resins, novolac type epoxy resins, biphenyl type epoxy resins, trishydroxyphenylmethane type resins or tetraphenylolethane type epoxy resins are particularly preferred. This is because these epoxy resins are rich in reactivity with a phenol resin as a curing agent and are excellent in heat resistance and the like.

  Further, the phenol resin acts as a curing agent for the epoxy resin, for example, a novolac type phenol resin such as a phenol novolac resin, a phenol aralkyl resin, a cresol novolac resin, a tert-butylphenol novolac resin, a nonylphenol novolac resin, Examples include resol-type phenolic resins and polyoxystyrenes such as polyparaoxystyrene. These can be used alone or in combination of two or more. Of these phenol resins, phenol novolac resins and phenol aralkyl resins are particularly preferred. This is because the connection reliability of the semiconductor device can be improved.

  The mixing ratio of the epoxy resin and the phenol resin is preferably such that, for example, the hydroxyl group in the phenol resin is 0.5 to 2.0 equivalents per equivalent of epoxy group in the epoxy resin component. More preferred is 0.8 to 1.2 equivalents. That is, if the blending ratio of both is out of the above range, sufficient curing reaction does not proceed and the properties of the cured epoxy resin are likely to deteriorate.

  In the present invention, an underfill material using an epoxy resin, a phenol resin and an acrylic resin is particularly preferable. Since these resins have few ionic impurities and high heat resistance, the reliability of the semiconductor element can be ensured. In this case, the mixing ratio of the epoxy resin and the phenol resin is 10 to 200 parts by weight with respect to 100 parts by weight of the acrylic resin component.

  The thermosetting acceleration catalyst for epoxy resin and phenol resin is not particularly limited, and can be appropriately selected from known thermosetting acceleration catalysts. A thermosetting acceleration | stimulation catalyst can be used individually or in combination of 2 or more types. As the thermosetting acceleration catalyst, for example, an amine curing accelerator, a phosphorus curing accelerator, an imidazole curing accelerator, a boron curing accelerator, a phosphorus-boron curing accelerator, or the like can be used.

  A flux may be added to the underfill material 2 in order to remove the oxide film on the surface of the solder bump and facilitate mounting of the semiconductor element. The flux is not particularly limited, and a conventionally known compound having a flux action can be used.For example, diphenolic acid, adipic acid, acetylsalicylic acid, benzoic acid, benzylic acid, azelaic acid, benzylbenzoic acid, malonic acid, 2,2-bis (hydroxymethyl) propionic acid, salicylic acid, o-methoxybenzoic acid, m-hydroxybenzoic acid, succinic acid, 2,6-dimethoxymethylparacresol, benzoic hydrazide, carbohydrazide, malonic dihydrazide, succinic acid Acid dihydrazide, glutaric acid dihydrazide, salicylic acid hydrazide, iminodiacetic acid dihydrazide, itaconic acid dihydrazide, citric acid trihydrazide, thiocarbohydrazide, benzophenone hydrazone, 4,4'-oxybisbenzenesulfonylhydrazide and Adipic acid dihydrazide, and the like. The addition amount of the flux is only required to exhibit the above flux effect, and is usually about 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin component contained in the underfill material.

  In the present embodiment, the underfill material 2 may be colored as necessary. In the underfill material 2, the color exhibited by coloring is not particularly limited. For example, black, blue, red, green, and the like are preferable. In coloring, it can be appropriately selected from known colorants such as pigments and dyes.

  When the underfill material 2 of the present embodiment is previously crosslinked to some extent, a polyfunctional compound that reacts with a functional group at the molecular chain end of the polymer is added as a crosslinking agent during the production. Good. Thereby, the adhesive property under high temperature can be improved and heat resistance can be improved.

  As the crosslinking agent, polyisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, an adduct of polyhydric alcohol and diisocyanate are more preferable. The addition amount of the crosslinking agent is usually preferably 0.05 to 7 parts by weight with respect to 100 parts by weight of the polymer. When the amount of the cross-linking agent is more than 7 parts by weight, the adhesive force is lowered, which is not preferable. On the other hand, if it is less than 0.05 parts by weight, the cohesive force is insufficient, which is not preferable. Moreover, you may make it include other polyfunctional compounds, such as an epoxy resin, together with such a polyisocyanate compound as needed.

  The underfill material 2 can be appropriately mixed with an inorganic filler. The blending of the inorganic filler makes it possible to impart conductivity, improve thermal conductivity, adjust the storage elastic modulus, and the like.

  Examples of the inorganic filler include silica, clay, gypsum, calcium carbonate, barium sulfate, alumina, beryllium oxide, silicon carbide, silicon nitride, and other ceramics, aluminum, copper, silver, gold, nickel, chromium, lead. And various inorganic powders made of metals such as tin, zinc, palladium, solder, or alloys, and other carbons. These can be used alone or in combination of two or more. Among these, silica, particularly fused silica is preferably used.

  Although the average particle diameter of the inorganic filler is not particularly limited, it is preferably in the range of 0.005 to 10 μm, more preferably in the range of 0.01 to 5 μm, and still more preferably 0.1 to 2. 0.0 μm. When the average particle size of the inorganic filler is less than 0.005 μm, the flexibility of the underfill material is reduced. On the other hand, when the average particle size exceeds 10 μm, the particle size is large with respect to the gap sealed by the underfill material, which causes a decrease in sealing performance. In the present invention, inorganic fillers having different average particle sizes may be used in combination. The average particle size is a value determined by a photometric particle size distribution meter (manufactured by HORIBA, apparatus name: LA-910).

  The blending amount of the inorganic filler is preferably 10 to 400 parts by weight, more preferably 50 to 250 parts by weight with respect to 100 parts by weight of the organic resin component. If the blending amount of the inorganic filler is less than 10 parts by weight, the storage elastic modulus may be lowered and the stress reliability of the package may be greatly impaired. On the other hand, if it exceeds 400 parts by weight, the fluidity of the underfill material 2 may be reduced, and may not be sufficiently embedded in the irregularities of the substrate or semiconductor element, causing voids or cracks.

  In addition to the said inorganic filler, other additives can be suitably mix | blended with the underfill material 2 as needed. Examples of other additives include flame retardants, silane coupling agents, ion trapping agents, and the like. Examples of the flame retardant include antimony trioxide, antimony pentoxide, brominated epoxy resin, and the like. These can be used alone or in combination of two or more. Examples of the silane coupling agent include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and the like. These compounds can be used alone or in combination of two or more. Examples of the ion trapping agent include hydrotalcites and bismuth hydroxide. These can be used alone or in combination of two or more.

  In this embodiment, the minimum melt viscosity at 100 to 200 ° C. of the underfill material 2 before thermosetting is preferably 100 Pa · s or more and 20000 Pa · s or less, and is 1000 Pa · s or more and 10,000 Pa · s or less. Is more preferable. By setting the minimum melt viscosity within the above range, the connection member 4 (see FIG. 2A) can easily enter the underfill material 2. In addition, generation of voids during electrical connection of the semiconductor element 5 and protrusion of the underfill material 2 from the space between the semiconductor element 5 and the adherend 6 can be prevented (FIG. 2D). reference).

  Further, the viscosity at 23 ° C. of the underfill material 2 before thermosetting is preferably 0.01 MPa · s or more and 100 MPa · s or less, and more preferably 0.1 MPa · s or more and 10 MPa · s or less. . Since the underfill material before thermosetting has a viscosity in the above range, the holding property of the semiconductor wafer 3 (see FIG. 2B) during dicing and the handleability during work can be improved.

  Further, the water absorption rate of the underfill material 2 before thermosetting under the conditions of a temperature of 23 ° C. and a humidity of 70% is preferably 1% by weight or less, and more preferably 0.5% by weight or less. When the underfill material 2 has a water absorption rate as described above, absorption of moisture into the underfill material 2 is suppressed, and generation of voids when the semiconductor element 5 is mounted can be more efficiently suppressed. The lower limit of the water absorption rate is preferably as small as possible, substantially 0% by weight is preferable, and 0% by weight is more preferable.

  Although the thickness of the underfill material 2 (total thickness in the case of multiple layers) is not particularly limited, considering the strength of the underfill material 2 and the filling property of the space between the semiconductor element 5 and the adherend 6, it is 10 μm or more. It may be about 100 μm or less. Note that the thickness of the underfill material 2 may be appropriately set in consideration of the gap between the semiconductor element 5 and the adherend 6 and the height of the connection member.

  The underfill material 2 of the sealing sheet 10 is preferably protected by a separator (not shown). The separator has a function as a protective material that protects the underfill material 2 until it is practically used. The separator is peeled off when the semiconductor wafer 3 is stuck on the underfill material 2 of the sealing sheet. As the separator, a plastic film or paper surface-coated with a release agent such as polyethylene terephthalate (PET), polyethylene, polypropylene, a fluorine release agent, or a long-chain alkyl acrylate release agent can be used.

(Method for producing sealing sheet)
The method for manufacturing a sealing sheet according to the present embodiment includes a step of forming the underfill material 2 on the substrate 1.

  Examples of the method for forming the substrate 1 include a calendar film forming method, a casting method in an organic solvent, an inflation extrusion method in a closed system, a T-die extrusion method, a co-extrusion method, and a dry lamination method. The material shown above may be used as the material of the substrate 1.

  When the substrate is used as a release film, the production method is not particularly limited. For example, a release coating layer such as a silicone layer is formed on the bonding surface of the substrate with the underfill material to release the substrate. It can be a film.

  As the step of forming the underfill material 3, for example, a step of forming an application layer by applying an adhesive composition solution that is a constituent material of the underfill material on a release film as the substrate 1 is performed. Then, the method of performing the process of drying the said application layer is mentioned.

  The method for applying the adhesive composition solution is not particularly limited, and examples thereof include a method using a comma coating method, a fountain method, a gravure method, and the like. The coating thickness may be appropriately set so that the thickness of the underfill material finally obtained by drying the coating layer is within the range shown above. Furthermore, it does not specifically limit as a viscosity of an adhesive composition solution, 400-2500 mPa * s is preferable in 25 degreeC, 800-2000 mPa * s is more preferable.

  What is necessary is just to perform drying of the said coating layer by throwing into a common heating furnace etc. In that case, you may spray a drying wind on a coating layer.

  The drying time is appropriately set according to the coating thickness of the adhesive composition solution, and is usually in the range of 1 to 5 minutes, preferably 2 to 4 minutes. If the drying time is less than 1 min, the amount of the remaining solvent is large, which may cause problems of outgas and voids in the subsequent process. On the other hand, if it exceeds 5 minutes, the curing reaction proceeds too much, and the fluidity and embedding property of the bumps of the semiconductor wafer may be reduced.

  A drying temperature is not specifically limited, Usually, it sets within the range of 70-160 degreeC. However, in the present invention, it is preferable that the drying temperature is increased stepwise as the drying time elapses. Specifically, for example, it is set within a range of 70 ° C. to 100 ° C. in the initial stage of drying (1 min or less immediately after drying), and is set within a range of 100 to 160 ° C. in the late stage of drying (over 1 min and 5 min or less). . Thereby, generation | occurrence | production of the pinhole on the surface of an application layer which arises when a drying temperature is raised rapidly immediately after coating can be prevented.

  Furthermore, the release film may be bonded to the other surface of the underfill material, and this may be used as a protective film for a sealing sheet, and peeled off when bonded to a semiconductor wafer or the like. Thereby, the sealing sheet which concerns on this embodiment which has an underfill material can be manufactured.

[Lamination process]
In the bonding step, the surface of the semiconductor wafer on which the connection member is formed is bonded to the sealing sheet (see FIG. 2A).

(Semiconductor wafer)
As the semiconductor wafer 3, a plurality of connection members 4 may be formed on one surface 3a (see FIG. 2A), and connection members may be formed on both surfaces 3a and 3b of the semiconductor wafer 3. (Not shown). The material of the connection member such as a bump or a conductive material 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, Examples thereof include solders (alloys) such as a tin-zinc-bismuth metal material, a gold metal material, and a copper metal material. The height of the connecting member is also determined according to the application, and is generally about 15 to 100 μm. Of course, the height of each connection member in the semiconductor wafer 3 may be the same or different.

  When connection members are formed on both surfaces of the semiconductor wafer, the connection members may or may not be electrically connected to each other. Examples of the electrical connection between the connection members include a connection through a via called a TSV format.

In the method for manufacturing a semiconductor device according to the present embodiment, the thickness of the underfill material includes a height X (μm) of the connecting member formed on the surface of the semiconductor wafer and a thickness Y (μm) of the underfill material. However, it is preferable to satisfy | fill the following relationship.
0.5 ≦ Y / X ≦ 2

  When the height X (μm) of the connecting member and the thickness Y (μm) of the cured film satisfy the above relationship, the space between the semiconductor element and the adherend can be sufficiently filled. Further, excessive protrusion of the underfill material from the space can be prevented, and contamination of the semiconductor element by the underfill material can be prevented. In addition, when the height of each connection member differs, the height of the highest connection member is used as a reference.

(Lamination)
As shown in FIG. 2A, first, a separator arbitrarily provided on the underfill material 2 of the sealing sheet 10 is appropriately peeled off, and the surface (connection) of the semiconductor wafer 3 on which the connection member 4 is formed. The member forming surface) 3a and the underfill material 2 are opposed to each other, and the underfill material 2 and the semiconductor wafer 3 are bonded together (mounting step).

  The method of bonding is not particularly limited, but a method by pressure bonding is preferable. The crimping is usually performed by a known pressing means such as a crimping roll while applying a pressure of 0.1 to 1 MPa, more preferably 0.3 to 0.7 MPa. Under the present circumstances, you may make it press-fit, heating at about 40-100 degreeC. Moreover, in order to improve adhesiveness, it is also preferable to press-fit under reduced pressure (1-1000 Pa).

[Dicing process]
In the dicing process, as shown in FIG. 2B, the semiconductor wafer is diced to form a semiconductor element with an underfill material. By passing through a dicing process, the semiconductor wafer 3 is cut into a predetermined size and divided into pieces (small pieces), and a semiconductor chip (semiconductor element) 5 is manufactured. The semiconductor chip 5 obtained here is integrated with the underfill material 2 cut into the same shape. Dicing is performed according to a conventional method from the surface 3b opposite to the surface 3a to which the underfill material 2 of the semiconductor wafer 3 is bonded. The alignment of the cut portion can be performed by image recognition using direct light, indirect light, or infrared (IR).

  In this step, for example, a cutting method called full cut for cutting up to the sealing 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. Moreover, since the semiconductor wafer is bonded and fixed with excellent adhesion by a sealing sheet having an underfill material, chip chipping and chip jump can be suppressed, and damage to the semiconductor wafer can also be suppressed. In addition, when the underfill material is formed of a resin composition containing an epoxy resin, even if the underfill material is cut by dicing, the underfill material of the underfill material is prevented or prevented from protruding on the cut surface. Can do. As a result, it is possible to suppress or prevent the cut surfaces from reattaching (blocking), and the pickup described later can be performed more satisfactorily.

  In addition, when expanding a sealing sheet 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 sealing sheet through a dicing ring, and an inner ring that has a smaller diameter than the outer ring and supports the sealing sheet. By this expanding process, it is possible to prevent adjacent semiconductor chips from coming into contact with each other and being damaged in a pickup process described later.

[Pickup process]
In order to collect the semiconductor chip 5 adhered and fixed to the sealing sheet, as shown in FIG. 2C, the semiconductor chip 5 with the underfill material 2 is picked up, and the semiconductor chip 5 and the underfill material 3 are picked up. The laminate A is peeled from the substrate 1.

  The pickup method is not particularly limited, and various conventionally known methods can be employed. For example, the method of pushing up each semiconductor chip from the base material side of a laminated film with a needle, and picking up the pushed-up semiconductor chip with a pickup device, etc. are mentioned. The picked-up semiconductor chip 5 constitutes a laminate A integrally with the underfill material 2 bonded to the surface 3a.

[Holding process]
In the holding step, the semiconductor element 5 (laminated body A) with the underfill material 2 is held at 100 to 200 ° C. for 1 second or longer. As a result, moisture in the underfill material can be reduced or removed. As a result, generation of voids during mounting of the semiconductor element can be suppressed, and a highly reliable semiconductor device can be manufactured.

  The holding temperature is not particularly limited as long as it is 100 to 200 ° C., and can be appropriately selected in consideration of the amount of moisture in the underfill material 2 and the moisture diffusibility. Furthermore, when the viewpoint of production efficiency is considered, it is preferable that it is 120-180 degreeC, and it is more preferable that it is 140-160 degreeC.

  The holding time is not particularly limited as long as it is 1 second or longer, and can be appropriately selected in consideration of the amount of moisture in the underfill material 2 and the moisture dissipating property, similarly to the holding temperature. Considering the viewpoint of production efficiency, it is preferably 1 second to 60 minutes, more preferably 1 second to 2 minutes, and further preferably 1 second to 1 minute.

  This holding process may be performed in the pickup apparatus while changing the setting of the pickup apparatus and moving from the pickup process to the mounting process, and is performed by separately allowing the laminate A to stay in the heating furnace for a predetermined time. May be.

[Mounting process]
In the mounting process, the semiconductor element and the adherend are electrically connected through the connecting member while filling the space between the adherend and the semiconductor element with the underfill material (see FIG. 2D). Specifically, the semiconductor chip 5 of the stacked body A is fixed to the adherend 6 according to a conventional method with the connection member forming surface 3a of the semiconductor chip 5 facing the adherend 6. For example, bumps (connection members) 4 formed on the semiconductor chip 5 are brought into contact with a bonding conductive material 7 (solder or the like) attached to the connection pads of the adherend 6 while pressing the conductive material. By melting, the electrical connection between the semiconductor chip 5 and the adherend 6 can be secured, and the semiconductor chip 5 can be fixed to the adherend 6. Since the underfill material 2 is affixed to the connection member forming surface 3 a of the semiconductor chip 5, the electrical connection between the semiconductor chip 5 and the adherend 6 and at the same time between the semiconductor chip 5 and the adherend 6 are performed. Are filled with the underfill material 2.

  Generally, the heating condition in the mounting process is 100 to 300 ° C., and the pressurizing condition is 0.5 to 500 N. Moreover, you may perform the thermocompression-bonding process in a mounting process in multistep. For example, it is possible to adopt a procedure in which treatment is performed at 150 ° C. and 100 N for 10 seconds and then treatment is performed at 300 ° C. and 100 to 200 N for 10 seconds. By performing thermocompression bonding in multiple stages, the resin between the connection member and the pad can be efficiently removed, and a better metal-to-metal bond can be obtained.

  As the adherend 6, various substrates such as a lead frame and a circuit board (such as a wiring circuit board), and other semiconductor elements can be used. The material of the substrate is not particularly limited, and examples thereof include a ceramic substrate and a plastic substrate. Examples of the plastic substrate include an epoxy substrate, a bismaleimide triazine substrate, a polyimide substrate, and a glass epoxy substrate.

  In the mounting process, one or both of the connection member and the conductive material are melted to connect the bumps 4 on the connection member forming surface 3a of the semiconductor chip 5 and the conductive material 7 on the surface of the adherend 6. However, the temperature at the time of melting of the bumps 4 and the conductive material 7 is usually about 260 ° C. (for example, 250 ° C. to 300 ° C.). The sealing sheet according to the present embodiment can have heat resistance that can withstand high temperatures in the mounting process by forming the underfill material 2 with an epoxy resin or the like. The melting point of the bump can be measured by measuring 10 mg of a metal having the same composition as the bump in a heating process at 5 ° C./min using DSC (Differential Scanning Colorimeter).

[Underfill material curing process]
After the electrical connection between the semiconductor element 5 and the adherend 6 is performed, the underfill material 2 is cured by heating. Thereby, the surface of the semiconductor element 5 can be protected, and the connection reliability between the semiconductor element 5 and the adherend 6 can be ensured. It does not specifically limit as heating temperature for hardening of an underfill material, What is necessary is just about 150-250 degreeC.

[Sealing process]
Next, a sealing step may be performed in order to protect the entire semiconductor device 20 including the mounted semiconductor chip 5. The sealing step is performed using a sealing resin. Although it does not specifically limit as sealing conditions at this time, Usually, the thermosetting of the sealing resin is performed by heating at 175 ° C. for 60 seconds to 90 seconds, but the present invention is not limited thereto, For example, it can be cured at 165 ° C. to 185 ° C. for several minutes.

  The sealing resin is not particularly limited as long as it is an insulating resin (insulating resin), and can be appropriately selected from sealing materials such as known sealing resins. Is more preferable. As sealing resin, the resin composition containing an epoxy resin etc. are mentioned, for example. Examples of the epoxy resin include the epoxy resins exemplified above. Moreover, as a sealing resin by the resin composition containing an epoxy resin, in addition to an epoxy resin, a thermosetting resin other than an epoxy resin (such as a phenol resin) or a thermoplastic resin may be included as a resin component. Good. In addition, as a phenol resin, it can utilize also as a hardening | curing agent of an epoxy resin, As such a phenol resin, the phenol resin illustrated above etc. are mentioned.

[Semiconductor device]
Next, a semiconductor device obtained using the sealing sheet will be described with reference to the drawing (see FIG. 2D). In the semiconductor device 20 according to the present embodiment, the semiconductor element 5 and the adherend 6 are connected via the bump (connection member) 4 formed on the semiconductor element 5 and the conductive material 7 provided on the adherend 6. Are electrically connected. An underfill material 2 is disposed between the semiconductor element 5 and the adherend 6 so as to fill the space. Since the semiconductor device 20 is obtained by the above manufacturing method using the sealing sheet 10, generation of voids when the semiconductor element 5 is mounted is suppressed. Therefore, the surface protection of the semiconductor element 5 and the filling of the space between the semiconductor element 5 and the adherend 6 are at a sufficient level, and the semiconductor device 20 can exhibit high reliability.

  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 the examples 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 sheet)
Acrylic ester polymer based on ethyl acrylate-methyl methacrylate (trade name “Paracron W-197CM” manufactured by Negami Kogyo Co., Ltd.): 100 parts, epoxy resin 1 (trade name “Epicoat 1004” JER stock 56 parts, epoxy resin 2 (trade name “Epicoat 828” manufactured by JER Corporation): 19 parts, phenol resin (trade name “Millex XLC-4L” manufactured by Mitsui Chemicals): 75 parts, spherical silica ( Product name “SO-25R” manufactured by Admatechs Co., Ltd.): 167 parts, organic acid (trade name “Orthoanisic acid” manufactured by Tokyo Chemical Industry Co., Ltd.): 1.3 parts, imidazole catalyst (trade name “2PHZ-PW” Shikoku Chemicals) (Manufactured by Co., Ltd.): A solution of an adhesive composition in which 1.3 parts are dissolved in methyl ethyl ketone and the solid content concentration becomes 23.6% by weight. It was prepared.

  The adhesive composition solution was applied onto a release film made of a polyethylene terephthalate film having a thickness of 50 μm and subjected to silicone release treatment as a substrate, and then dried at 130 ° C. for 2 minutes to obtain a thickness of 45 μm. A sealing sheet in which an underfill material was formed on a substrate was produced.

(Fabrication of semiconductor devices)
Prepare a silicon wafer with single-sided bumps with bumps formed on one side, and bond the prepared sealing sheet to the surface on which the bumps of the silicon wafer with single-sided bumps are formed, with an underfill material as the bonding surface Pasted together. As a silicon wafer with a single-sided bump, the following was used. The bonding conditions are as follows. The ratio (Y / X) of the thickness Y (= 45 μm) of the underfill material to the height X (= 45 μm) of the connecting member was 1.

<Silicon wafer with single-sided bump>
Silicon wafer diameter: 8 inches Silicon wafer thickness: 0.2 mm (200 μm)
Bump height: 45μm
Bump pitch: 50 μm
Bump material: Solder

<Bonding conditions>
Pasting device: Product name “DSA840-WS” manufactured by Nitto Seiki Co., Ltd. Pasting speed: 5 mm / min
Pasting pressure: 0.25 MPa
Stage temperature at the time of pasting: 80 ° C
Degree of vacuum when pasting: 150 Pa

  After bonding the silicon wafer with a single-sided bump and the sealing sheet according to the above procedure, dicing was performed under the following conditions. Dicing was fully cut so as to obtain a chip size of 7.3 mm square.

<Dicing conditions>
Dicing machine: Trade name “DFD-6361” manufactured by Disco Corporation Dicing ring: “2-8-1” (manufactured by Disco Corporation)
Dicing speed: 30mm / sec
Dicing blade:
Z1; "203O-SE 27HCDD" manufactured by DISCO
Z2: “203O-SE 27HCBB” manufactured by Disco Corporation
Dicing blade rotation speed:
Z1; 40,000 rpm
Z2; 45,000 rpm
Cut method: Step cut Wafer chip size: 7.3mm square

  Next, the laminated body of the underfill material and the semiconductor chip with single-sided bumps was picked up by a push-up method using a needle from the base material side of each sealing sheet. The pickup conditions are as follows.

<Pickup conditions>
Pickup device: Brand name “SPA-300” manufactured by Shinkawa Co., Ltd. Number of needles: 9 Needle push-up amount: 500 μm (0.5 mm)
Needle push-up speed: 20 mm / second Pickup time: 1 second Expanding amount: 3 mm

Subsequently, the picked-up laminate was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 150 ° C. × 2 seconds

  Finally, under the following thermocompression bonding conditions, the semiconductor chip was mounted on the BGA substrate by thermocompression bonding with the bump forming surface of the semiconductor chip facing the BGA substrate. Thus, a semiconductor device in which the semiconductor chip was mounted on the BGA substrate was obtained. In this step, a two-step process of performing thermocompression bonding under thermocompression bonding condition 2 following thermocompression bonding condition 1 was performed.

<Thermocompression condition 1>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating temperature: 150 ° C.
Load: 98N
Holding time: 10 seconds

<Thermocompression condition 2>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating temperature: 260 ° C.
Load: 98N
Holding time: 10 seconds

[Example 2]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 100 ° C. × 2 seconds

[Example 3]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 200 ° C. × 2 seconds

[Example 4]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 150 ° C. × 1 second

[Example 5]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 100 ° C. × 1 second

[Example 6]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 200 ° C. × 1 second

[Comparative Example 1]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 50 ° C. × 2 seconds

[Comparative Example 2]
A semiconductor device was fabricated in the same manner as in Example 1 except that the stacked body of the semiconductor element and the underfill material was held under the following heating conditions.
<Heating conditions>
Pickup device: Product name “FCB-3” manufactured by Panasonic Heating conditions: 250 ° C. × 2 seconds

[Comparative Example 3]
A semiconductor device was manufactured in the same manner as in Example 1 except that the step of holding the laminated body of the semiconductor element and the underfill material was not provided.

(Measurement of minimum melt viscosity)
The minimum melt viscosity of the underfill material (before thermosetting) was measured. The measurement of the minimum melt viscosity is a value measured by a parallel plate method using a rheometer (manufactured by HAAKE, RS-1). More specifically, the melt viscosity is measured in the range of 60 ° C. to 200 ° C. under the conditions of a gap of 100 μm, a rotating cone diameter of 20 mm, a rotating speed of 10 s ⁻¹ , and a heating rate of 10 ° C./min, and is obtained at that time. The lowest melt viscosity in the range from 100 ° C. to 200 ° C. was defined as the lowest melt viscosity. The results are shown in Table 1.

(Evaluation of void generation)
Evaluation of void generation is performed by cutting between the underfill material of the semiconductor device manufactured in the example and the comparative example and the BGA substrate, and the cut surface is an image recognition device (trade name “C9597-1” manufactured by Hamamatsu Photonics). ) And calculating the ratio of the total area of the void portion to the area of the semiconductor chip. The case where the total area of the void portion is 0 to 5% with respect to the area of the semiconductor chip in the observation image of the cut surface is “◯”, the case of more than 5% and 25% or less is “△”, the case of more than 25% Evaluated as “x”. The results are shown in Table 1.

  As can be seen from Table 1, in the semiconductor device according to the example, generation of voids was suppressed. On the other hand, voids occurred in the semiconductor devices of Comparative Examples 1 to 3. In Comparative Example 1, since the holding temperature was less than 100 ° C., the moisture in the underfill material was not sufficiently removed, and it is considered that the moisture was evaporated and the void was generated by the heating at the time of mounting the semiconductor element. In Comparative Example 2, since the holding temperature exceeded 200 ° C., it was considered that the moisture in the underfill material was rapidly evaporated and as a result, voids were generated. In Comparative Example 3, since no holding step was provided, it was considered that moisture in the underfill material was not removed and voids were generated. As described above, a highly reliable semiconductor device in which generation of voids is suppressed is provided by providing a step of holding a semiconductor element with an underfill material at 100 to 200 ° C. for 1 second or longer as a semiconductor device manufacturing step. I can see that

DESCRIPTION OF SYMBOLS 1 Base material 2 Underfill material 3 Semiconductor wafer 3a The surface in which the connection member of the semiconductor wafer was formed 3b The surface on the opposite side to the surface in which the connection member of the semiconductor wafer was formed 4 Bump (connection member)
5 Semiconductor chip (semiconductor element)
6 adherend 7 conductive material 10 sealing sheet 20 semiconductor device

Claims (4)

A method for manufacturing a semiconductor device comprising an adherend, a semiconductor element electrically connected to the adherend, and an underfill material that fills a space between the adherend and the semiconductor element,
Preparing a sealing sheet comprising a substrate and an underfill material laminated on the substrate;
Bonding the sealing sheet to the surface on which the connecting member of the semiconductor wafer is formed;
Forming a semiconductor element with the underfill material by dicing the semiconductor wafer;
Holding the semiconductor element with the underfill material at 100 to 200 ° C. for 1 second or more;
A step of electrically connecting the semiconductor element and the adherend via the connecting member while filling a space between the adherend and the semiconductor element with an underfill material. .   2. The method of manufacturing a semiconductor device according to claim 1, wherein a minimum melt viscosity at 100 to 200 ° C. of the underfill material before thermosetting is 100 Pa · s or more and 20000 Pa · s or less.   The method for manufacturing a semiconductor device according to claim 1, wherein the underfill material before thermosetting has a viscosity at 23 ° C. of 0.01 MPa · s to 100 MPa · s. The method for manufacturing a semiconductor device according to any one of claims 1 to 3, wherein the underfill material before thermosetting has a water absorption of 1% by weight or less under conditions of a temperature of 23 ° C and a humidity of 70%.

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