JP6972216B2 - Heat bonding sheet, heat bonding sheet with dicing tape, manufacturing method of bonded body, power semiconductor device - Google Patents

Description

The present invention relates to a heat bonding sheet, a heat bonding sheet with a dicing tape, a method for manufacturing a bonded body, and a power semiconductor device.

In the manufacture of semiconductor devices, the method of adhering a semiconductor element to an adherend such as a metal lead frame (so-called die bonding method) has changed from the conventional gold-silicon eutectic system to the solder and resin paste methods. Nowadays, conductive resin pastes may be used.

In recent years, power semiconductor devices that control and supply electric power have become widespread. Since a current always flows through a power semiconductor device, the amount of heat generated is large. Therefore, it is desirable that the conductive adhesive used in the power semiconductor device has high heat dissipation and low electrical resistivity.

Power semiconductor devices are required to operate at high speed with low loss. Conventionally, semiconductors using Si such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) have been used for power semiconductor devices. In recent years, semiconductors such as SiC and GaN have been developed and are expected to expand in the future.

Semiconductors using SiC or GaN have features such as a large bandgap and a high dielectric breakdown electric field, and are capable of low loss, high-speed operation, and high-temperature operation. High-temperature operation is an advantage in automobiles and small power conversion equipment where the thermal environment is harsh. Semiconductor devices for applications with severe thermal environments are expected to operate at high temperatures of around 250 ° C., and conventional bonding / adhesive materials such as solder and conductive adhesives have problems with thermal characteristics and reliability. Therefore, conventionally, a paste material containing sintered metal particles has been proposed (see, for example, Patent Document 1). The sintered metal particle-containing paste material contains nano- and micro-sized metal particles, and these metal particles are melted at a temperature lower than the normal melting point due to the nano-sized effect, and sintering between the particles proceeds.

Japanese Unexamined Patent Publication No. 2014-111800

The sintered metal particle-containing paste material often contains silver-based particles as the sintered metal particles. However, there is a problem that it becomes expensive if a precious metal called silver is used as a main component.
Further, since the paste material containing sintered metal particles is in a paste state, there is a problem that variations occur at the time of coating and the yield of the manufactured bonded body is lowered.

The present invention has been made in view of the above-mentioned problems, and an object thereof is a heat-bonding sheet, which is inexpensive and capable of improving the yield of a manufactured bonded body, and the heat-bonding sheet. It is an object of the present invention to provide a sheet for heat bonding with a dicing tape having a dicing tape. Another object of the present invention is to provide a method for manufacturing a bonded body using the heat bonding sheet. Another object of the present invention is to provide a power semiconductor device having the heat bonding sheet.

Conventionally, it is known that the sintering temperature (temperature at which sintering proceeds at an accelerated rate) of low-temperature sinterable copper particles is about 260 to 270 ° C. Further, when a heat-bonding sheet containing copper particles is examined, since the copper particles alone do not form a sheet, it is conceivable that the sheet is formed after containing a binder (for example, a thermally decomposable binder). However, the temperature at which the binder thermally decomposes is often close to or higher than the sintering temperature of the copper particles. Therefore, there is a problem that the binder still remains at the time of sintering the copper particles, and the sintering does not proceed favorably.

The inventors of the present application have studied to solve the above problems. As a result, it was found that when the sheet containing the copper particles and the polycarbonate is heated, the temperature at which the polycarbonate is thermally decomposed is surprisingly lowered, which is somewhat lower than the sintering temperature of the copper particles. If copper particles are used as the sintered metal particles of the heat-bonding sheet and polycarbonate is used as the binder, most of the polycarbonate is thermally decomposed at an early stage of the sintering process, which has an influence on the sintering of the copper particles. We found that it could be reduced.

The present invention has been made based on the above findings.

That is, the heat-bonding sheet according to the present invention is
It is characterized by having a presintering layer containing copper particles and polycarbonate.

According to the above configuration, since the presintering layer contains copper particles and polycarbonate, most of the polycarbonate is thermally decomposed at an early stage of the sintering process. As a result, the heat-bonding sheet having the pre-sintering layer can bond two objects to be bonded by utilizing the sintering of copper particles. In particular, since most polycarbonates are thermally decomposed at an early stage of the sintering process, sintering proceeds favorably. As a result, it becomes possible to obtain a bonded body having a high yield.
Further, according to the above configuration, since it is not a paste but a sheet, it is possible to suppress protrusion during pasting and creeping up to the surface of the object to be joined.
Further, since copper particles are used, it can be manufactured at a lower cost than when a precious metal such as silver is used.

In the above configuration, the average particle size of the copper particles is preferably in the range of 10 to 1000 nm.

When the average particle size of the copper particles is 1000 nm or less, the sintering temperature can be lowered more preferably. On the other hand, when the average particle size of the copper particles is 10 nm or more, the particles can be preferably dispersed in the sheet.

In the above configuration, the copper particles are composed of a plurality of crystallites.
The crystallite diameter of the crystallite is preferably 50 nm or less.

When the crystallite diameter of the crystallite is 50 nm or less, the sintering temperature can be further preferably lowered.

Further, the heat bonding sheet with dicing tape according to the present invention is
With dicing tape,
It is characterized by having the heat bonding sheet laminated on the dicing tape.

According to the heat bonding sheet with dicing tape, since it is integrated with the dicing tape, the step of bonding to the dicing tape can be omitted. Further, since the heat bonding sheet is provided, it is possible to obtain a bonded body having a high yield. Further, since the heat-bonding sheet is not a paste but a sheet, it is possible to suppress protrusion during pasting and creeping up to the surface of the object to be bonded.
Further, since copper particles are used for the heat-bonding sheet, it can be manufactured at a lower cost than when a noble metal such as silver is used.

Further, the method for manufacturing a bonded body according to the present invention is as follows.
The process of preparing the heat-bonding sheet and
Including a step of heat-bonding two objects to be bonded via the heat-bonding sheet.
The joining temperature in the heat joining step is characterized in that it is in the range of 200 to 400 ° C.

According to the above configuration, since the heat bonding sheet is used, most polycarbonates are thermally decomposed at an early stage of the sintering process if heat bonding (sintering of copper particles) is performed at 200 to 400 ° C. Therefore, sintering proceeds favorably. As a result, it becomes possible to obtain a bonded body having a high yield.

In the above configuration, the heat bonding step is preferably performed under a nitrogen atmosphere, a reduced pressure, or a reducing gas atmosphere.

Copper particles have the property of oxidizing at high temperatures. Further, when the object to be bonded is made of copper, it is oxidized at a high temperature. Therefore, if the step of heat-bonding is performed under a nitrogen atmosphere, a reduced pressure, or a reducing gas atmosphere, oxidation of copper particles and the like due to heating can be prevented.

Further, the power semiconductor device according to the present invention is
The heat-bonding sheet and
It is characterized by being provided with a power semiconductor element.

According to the above configuration, since the heat bonding sheet is provided, it is possible to provide a power semiconductor device having excellent thermal characteristics and reliability, which can be operated in a high temperature environment of, for example, about 250 ° C.

It is sectional drawing which shows the sheet for heat bonding with dicing tape which concerns on one Embodiment of this invention. It is sectional drawing which shows the sheet for heat bonding with dicing tape which concerns on other embodiment of this invention. It is sectional drawing which shows the sheet for heat bonding with a double-sided separator. It is sectional drawing for explaining one manufacturing method of the semiconductor device which concerns on this Embodiment.

(Sheet for heat bonding with dicing tape)
The heat-bonding sheet according to the embodiment of the present invention and the heat-bonding sheet with dicing tape will be described below. Examples of the heat-bonding sheet according to the present embodiment include the heat-bonding sheets with dicing tape described below in which the dicing tape is not attached. Therefore, in the following, the heat bonding sheet with dicing tape will be described, and the heat bonding sheet will be described therein. FIG. 1 is a schematic cross-sectional view showing a heat bonding sheet with a dicing tape according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing another heat bonding sheet with a dicing tape according to another embodiment of the present invention.

As shown in FIG. 1, the heat-bonding sheet 10 with a dicing tape has a structure in which the heat-bonding sheet 3 is laminated on the dicing tape 11. The dicing tape 11 is configured by laminating the pressure-sensitive adhesive layer 2 on the base material 1, and the heat-bonding sheet 3 is provided on the pressure-sensitive adhesive layer 2. Further, the heat-bonding sheet with dicing tape of the present invention may have a configuration in which the heat-bonding sheet 3'is formed only on the work-attached portion, as in the heat-bonding sheet 12 with dicing tape shown in FIG. ..

(Sheet for heat bonding)
The heat-bonding sheets 3 and 3'are in the form of sheets. Since it is a sheet rather than a paste, it is possible to suppress protrusion during pasting and creeping up to the surface of the object to be pasted.

The heat-bonding sheets 3 and 3'according to the present embodiment are composed of one layer before sintering. The pre-sintering layer is a layer that becomes a sintering layer by predetermined heating.

In this embodiment, a case where the heat bonding sheet is composed of one presintering layer will be described. However, the heat-bonding sheet of the present invention is not limited to this example as long as it has a presintering layer. The pre-sintering layer is not limited to one layer, and may be formed of a plurality of layers having different compositions.
Further, the heat-bonding sheet of the present invention may be, for example, a sheet composed of two or more layers of a presintering layer and another layer. For example, the heat-bonding sheet of the present invention may be a sheet in which the first presintering layer is exposed on one surface and the second presintering layer is exposed on the other surface. Specifically, the sheet may be a sheet in which the first pre-sintering layer, the other layer, and the second pre-sintering layer are laminated in this order. For example, in this case, the first pre-sintering layer and the second pre-sintering layer may have the same composition or may be different.

(Pre-sintering layer)
The sintering front layer 31 contains copper particles. The copper particles may be pure copper, and may be silicon (Si), phosphorus (P), carbon (C), zirconia (Zr), titanium (Ti), sulfur (S), chlorine (Cl), oxygen (O). ) Etc. may be used. The content of elements other than copper is preferably 0 to 2% by mass as a whole of copper and non-copper. When the copper particles are pure copper, heat bonding can be more preferably performed.

The average particle size of the copper particles is preferably in the range of 10 to 1000 nm, more preferably in the range of 50 to 800 nm, and even more preferably in the range of 100 to 500 nm. When the average particle size of the copper particles is 1000 nm or less, the sintering temperature can be lowered more preferably. On the other hand, when the average particle size of the copper particles is 10 nm or more, the dispersibility of the particles is improved.

The average particle size of the copper particles is measured by the following method.
1. 1. The presinter layer is ion-polished in a cooling environment to expose the cross section.
2. 2. The cross section is imaged using a field emission scanning electron microscope SU8020 (manufacturer: Hitachi High-Technologies Corporation). The imaging conditions are an acceleration voltage of 5 kV and a magnification of 50,000 times, and a reflected electron image is obtained as image data.
3. 3. Using the image analysis software Image J, the obtained image data is automatically binarized and then the average particle size of the particles is calculated.

The shape of the copper particles is not particularly limited, and is, for example, spherical, rod-shaped, scaly, or indefinite.

The copper particles are preferably composed of a plurality of crystallites. In this case, the crystallite diameter of the crystallite is preferably 50 nm or less, more preferably 45 nm or less. When the crystallite diameter of the crystallite is 50 nm or less, the sintering temperature can be further preferably lowered.
The crystallite diameter is a value calculated by the Scherrer method using the (111) peak obtained by performing X-ray diffraction measurement of copper powder using Ultima IV manufactured by Rigaku Co., Ltd.

The content of the copper particles is preferably in the range of 60 to 98% by weight, more preferably in the range of 65 to 97% by weight, and more preferably 70 to 95% by weight with respect to the entire presintering layer 31. It is more preferable that it is within the range of. When the metal fine particles are contained in the range of 60 to 98% by weight, the object to be bonded can be suitably bonded.

The sintering front layer 31 may contain a low boiling point binder. The low boiling point binder is used to facilitate the handling of the copper particles. The low boiling point binder is also used to adjust any mechanical properties. Specifically, it can be used as a copper particle-containing paste in which the copper particles are dispersed in the low boiling point binder.

The low boiling point binder is liquid at 23 ° C. As used herein, the term "liquid" includes semi-liquid. Specifically, it means that the viscosity at 23 ° C. by measuring the viscosity with a dynamic viscoelasticity measuring device (rheometer) is 100,000 Pa · s or less.
The conditions for measuring the viscosity are as follows.
Rheometer: MARS III manufactured by Thermo SCIENTFIC
Jig: Parallel plate 20 mmφ, gap 100 μm, shear rate 1 / sec)

Specific examples of the low boiling point binder include, for example, pentanol, hexanol, heptanol, octanol, 1-decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 2,4-diethyl-1,5 pentanediol and the like. Phyrogen and polyhydric alcohols, citronerol, geraniol, nerol, carveol, α-terpineol, terpene alcohols such as isobornylcyclohexanol, ethylene glycol butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, Diethylene glycol isobutyl ether, diethylene glycol hexyl ether, triethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol propyl Ethers such as ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, tripropylene glycol methyl ether, tripropylene glycol dimethyl ether, ethylene glycol ethyl ether acetate , Ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol buty ether acetate, dipropylene glycol methyl ether acetate (DPMA) and the like. These may be used in combination of two or more. Of these, it is preferable to use two types having different boiling points in combination. Using two types with different boiling points is excellent in maintaining the sheet shape. In particular, by containing terpene alcohol, it is possible to impart further flexibility to the presinter layer.

The sintering front layer 31 contains polycarbonate as a pyrolytic binder. Since polycarbonate is contained as a pyrolytic binder, it is easy to maintain the sheet shape before the heat bonding process. In addition, it is easily thermally decomposed during the heat bonding process.

The polycarbonate is not particularly limited as long as it can be thermally decomposed in the heat bonding step, but is not particularly limited, but an aromatic compound (for example, benzene) between the carbonic acid ester groups (-O-CO-O-) of the main chain. Examples thereof include an aliphatic polycarbonate which does not contain a ring and the like and is composed of an aliphatic chain, and an aromatic polycarbonate which contains an aromatic compound between carbonic acid ester groups (-O-CO-O-) of the main chain. Of these, aliphatic polycarbonate is preferable.
Examples of the aliphatic polycarbonate include polyethylene carbonate and polypropylene carbonate. Of these, polypropylene carbonate is preferable from the viewpoint of solubility in an organic solvent in the preparation of varnish for sheet formation.
Examples of the aromatic polycarbonate include those having a bisphenol A structure in the main chain.
The weight average molecular weight of the polycarbonate is preferably in the range of 10,000 to 1,000,000. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

The sintering front layer 31 may contain a pyrolytic binder other than the polycarbonate (hereinafter, also referred to as “another pyrolytic binder”).

As used herein, the term "thermally decomposable binder" refers to a binder that can be thermally decomposed in the heat bonding step. It is preferable that the thermally decomposable binder hardly remains in the sintered layer (pre-sintered layer 31 after heating) after the heat bonding step.

In addition to the above components, the presintering layer 31 may appropriately contain, for example, a flux component.

The heat-bonding sheets 3, 3'can be manufactured by a usual method. For example, a varnish containing each of the above components for forming the presintering layer 31 is prepared, and the varnish is applied onto the substrate separator to a predetermined thickness to form a coating film, and then the coating film is applied. By drying, sheets 3 and 3'for heat bonding can be manufactured.

The solvent used for the varnish is not particularly limited, but an organic solvent or an alcohol solvent capable of uniformly dissolving, kneading or dispersing each of the above components is preferable. Examples of the organic solvent include ketone solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, acetone, methylethylketone and cyclohexanone, toluene and xylene. The alcohol solvent includes ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2-. Examples thereof include butene-1,4-diol, 1,2,6-hexanetriol, glycerin, octanediol, 2-methyl-2,4-pentanediol and terpineol.

The coating method is not particularly limited. Examples of the solvent coating method include a die coater, a gravure coater, a roll coater, a reverse coater, a comma coater, a pipe doctor coater, and screen printing. Of these, a die coater is preferable because the coating thickness is highly uniform. The drying conditions of the coating film are not particularly limited, and for example, the drying can be performed at a drying temperature of 70 to 160 ° C. and a drying time of 1 to 5 minutes. Even after the coating film is dried, depending on the type of solvent, all of the solvent may remain in the coating film without being vaporized.

When the pre-sintering layer 31 contains the low boiling point binder, a part of the low boiling point binder may volatilize depending on the drying conditions. Therefore, the ratio of each component constituting the presintering layer 31 changes according to the drying conditions. For example, even in the case of the pre-sintering layer 31 formed of the same varnish, the higher the drying temperature and the longer the drying time, the more the content of metal fine particles in the entire pre-sintering layer 31 and the heat-decomposability. The content of the binder is high. Therefore, it is preferable to set the drying conditions so that the content of the metal fine particles and the thermally decomposable binder in the sintering prelayer 31 is a desired amount.

As the base material separator, a plastic film or paper surface-coated with a release agent such as polyethylene terephthalate (PET), polyethylene, polypropylene, a fluorine-based release agent, or a long-chain alkyl acrylate-based release agent can be used.

As a method for producing the heat-bonding sheets 3, 3', for example, a method in which the above components are mixed by a mixer and the obtained mixture is press-molded to produce the heat-bonding sheets 3, 3'is also suitable. Is. Examples of the mixer include a planetary mixer.

The thickness of the heat-bonding sheets 3 and 3'at 23 ° C. before heating is preferably 5 to 100 μm, more preferably 10 to 80 μm. When the thickness at 23 ° C. is 5 μm or more, the protrusion can be further suppressed. On the other hand, when it is 100 μm or less, the occurrence of inclination at the time of heat bonding can be further suppressed.

(Dicing tape)
The dicing tape 11 is configured by laminating the pressure-sensitive adhesive layer 2 on the base material 1.

The base material 1 serves as a strength base for the heat-bonding sheets 10 and 12 with a dicing tape, and is preferably one having ultraviolet transparency. Examples of the base material 1 include low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymerized polypropylene, block copolymerized polypropylene, homopolyprolene, polybutene, polymethylpentene and the like. Polyolefin, ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, ethylene -Hexen copolymer, polyurethane, polyethylene terephthalate, polyethylene naphthalate and other polyesters, polycarbonate, polyimide, polyether ether ketone, polyetherimide, polyamide, total aromatic polyamide, polyphenylsulfide, aramid (paper), glass, Examples thereof include glass cloth, fluororesin, polyvinyl chloride, polyvinylidene chloride, cellulose-based resin, silicone resin, metal (foil), and paper.

Further, examples of the material of the base material 1 include a polymer such as a crosslinked body of the resin. The plastic film may be used without stretching, or may be uniaxially or biaxially stretched, if necessary. According to the resin sheet to which heat shrinkage is imparted by stretching treatment or the like, the adhesive area between the pressure-sensitive adhesive layer 2 and the heat-bonding sheets 3 and 3'is reduced by heat-shrinking the base material 1 after dicing. It is possible to facilitate the recovery of semiconductor chips.

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

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

The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer 2 is not particularly limited, and for example, a general pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive and a rubber-based pressure-sensitive adhesive can be used. The pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive using an acrylic polymer as a base polymer from the viewpoint of cleanability with an organic solvent such as ultrapure water or alcohol of electronic parts that dislike contamination of semiconductor wafers and glass. Is preferable.

Examples of the acrylic polymer include (meth) acrylic acid alkyl esters (eg, methyl esters, ethyl esters, propyl esters, isopropyl esters, butyl esters, isobutyl esters, s-butyl esters, t-butyl esters, pentyl esters, and the like. 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, hexadecyl ester , Octadecyl esters, eicosyl esters, and other alkyl groups having 1 to 30 carbon atoms, particularly linear or branched alkyl esters having 4 to 18 carbon atoms) and (meth) acrylic acid cycloalkyl esters (eg, cyclopentyl). Examples thereof include an acrylic polymer using one or more of (ester, cyclohexyl ester, etc.) as a monomer component. The (meth) acrylic acid ester means an acrylic acid ester and / or a methacrylic acid ester, and all of them have the same meaning as the (meth) of the present invention.

The acrylic polymer contains units corresponding to other monomer components copolymerizable with the (meth) acrylic acid alkyl ester or cycloalkyl ester, if necessary, for the purpose of modifying cohesive force, heat resistance and the like. You may be. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; maleic anhydride. , Acid anhydride monomers such as itaconic acid anhydride; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate. , (Meta) acrylate 8-hydroxyoctyl, (meth) acrylate 10-hydroxydecyl, (meth) acrylate 12-hydroxylauryl, (4-hydroxymethylcyclohexyl) methyl (meth) acrylate and other hydroxyl group-containing monomers; Sulfuric acid groups such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalene sulfonic acid. Containing monomer; Phosphoric acid group-containing monomer such as 2-hydroxyethylacryloyl phosphate; acrylamide, acrylonitrile and the like can be mentioned. One or more of these copolymerizable monomer components can be used. The amount of these copolymerizable monomers used is preferably 40% by weight or less of the total monomer components.

Further, since the acrylic polymer is crosslinked, a polyfunctional monomer or the like can also be contained as a monomer component for copolymerization, if necessary. Examples of such a polyfunctional monomer include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, and neopentyl glycol di (meth) acrylate. Pentaerythritol di (meth) acrylate, trimethylolpropanthry (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) Examples include acrylate. One or more of these polyfunctional monomers can also be used. The amount of the polyfunctional monomer used is preferably 30% by weight or less of the total monomer components from the viewpoint of adhesive properties and the like.

The acrylic polymer is obtained by subjecting a single monomer or a mixture of two or more kinds of monomers to polymerization. The polymerization can be carried out by any method such as solution polymerization, emulsion polymerization, bulk polymerization and suspension polymerization. It is preferable that the content of the low molecular weight substance is small from the viewpoint of preventing contamination of a clean adherend. From this point of view, the number average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably about 200,000 to 3,000,000, and particularly preferably about 300,000 to 1,000,000.

Further, in order to increase the number average molecular weight of an acrylic polymer or the like as a base polymer, an external cross-linking agent can be appropriately adopted as the pressure-sensitive adhesive. Specific means of the external cross-linking method include a method of adding and reacting a so-called cross-linking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound and a melamine-based cross-linking agent. When an external cross-linking agent is used, the amount used is appropriately determined by the balance with the base polymer to be cross-linked and further by the intended use as a pressure-sensitive adhesive. Generally, it is preferably blended in an amount of about 5 parts by weight or less, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the base polymer. Further, as the pressure-sensitive adhesive, if necessary, in addition to the above-mentioned components, various conventionally known pressure-imparting agents, antiaging agents and other additives may be used.

The pressure-sensitive adhesive layer 2 can be formed by a radiation-curable pressure-sensitive adhesive. The radiation-curable pressure-sensitive adhesive can increase the degree of cross-linking by irradiation with radiation such as ultraviolet rays and easily reduce its adhesive strength, and the portion 2a corresponding to the work-attached portion of the pressure-sensitive adhesive layer 2 shown in FIG. By irradiating only the portion 2b, a difference in adhesive strength from the other portion 2b can be provided.

Further, by curing the radiation-curable pressure-sensitive adhesive layer 2 in accordance with the heat-bonding sheet 3'shown in FIG. 2, the portion 2a having a significantly reduced adhesive strength can be easily formed. Since the heat-bonding sheet 3'is attached to the portion 2a that has been hardened and has a reduced adhesive strength, the interface between the portion 2a of the pressure-sensitive adhesive layer 2 and the heat-bonding sheet 3'has a property of being easily peeled off at the time of pickup. Have. On the other hand, the portion not irradiated with radiation has sufficient adhesive strength and forms the portion 2b. The pressure-sensitive adhesive layer may be irradiated with radiation after dicing and before pickup.

As described above, in the pressure-sensitive adhesive layer 2 of the heat-bonding sheet 10 with dicing tape shown in FIG. 1, the portion 2b formed of the uncured radiation-curable pressure-sensitive adhesive adheres to the heat-bonding sheet 3 and is diced. It is possible to secure the holding power when doing. As described above, the radiation-curable pressure-sensitive adhesive can support the heat-bonding sheet 3 for fixing the chip-shaped work (semiconductor chip or the like) to the adherend such as a substrate in a well-balanced manner of adhesion and peeling. In the pressure-sensitive adhesive layer 2 of the heat-bonding sheet 11 with dicing tape shown in FIG. 2, the portion 2b can fix the wafer ring.

As the radiation-curable pressure-sensitive adhesive, one having a radiation-curable functional group such as a carbon-carbon double bond and exhibiting adhesiveness can be used without particular limitation. As the radiation-curable pressure-sensitive adhesive, for example, an additive-type radiation-curable pressure-sensitive adhesive in which a radiation-curable monomer component or an oligomer component is mixed with a general pressure-sensitive pressure-sensitive adhesive such as the acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive. The agent can be exemplified.

Examples of the radiation-curable monomer component to be blended include urethane oligomer, urethane (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerylate. Examples thereof include stall tetra (meth) acrylate, dipentaellistol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,4-butanediol di (meth) acrylate. Examples of the radiation-curable oligomer component include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based, and those having a molecular weight in the range of about 100 to 30,000 are suitable. The amount of the radiation-curable monomer component or oligomer component to be blended can be appropriately determined according to the type of the pressure-sensitive adhesive layer so as to be able to reduce the adhesive strength of the pressure-sensitive adhesive layer. Generally, it is, for example, about 5 to 500 parts by weight, preferably about 40 to 150 parts by weight, based on 100 parts by weight of a base polymer such as an acrylic polymer constituting the pressure-sensitive adhesive.

As the radiation-curable pressure-sensitive adhesive, in addition to the additive-type radiation-curable pressure-sensitive adhesive described above, a base polymer having a carbon-carbon double bond in the polymer side chain or in the main chain or at the end of the main chain. Examples thereof include an intrinsically curable pressure-sensitive adhesive using. Since the intrinsic radiation-curable pressure-sensitive adhesive does not need to contain the oligomer component, which is a small molecule component, or does not contain a large amount, the oligomer component, etc. does not move in the pressure-sensitive adhesive over time and is stable. It is preferable because a layered pressure-sensitive adhesive layer can be formed.

As the base polymer having a carbon-carbon double bond, one having a carbon-carbon double bond and having adhesiveness can be used without particular limitation. As such a base polymer, one having an acrylic polymer as a basic skeleton is preferable. Examples of the basic skeleton of the acrylic polymer include the above-exemplified acrylic polymers.

The method for introducing a carbon-carbon double bond into the acrylic polymer is not particularly limited, and various methods can be adopted, but the carbon-carbon double bond is easily introduced into the polymer side chain in terms of molecular design. Is. For example, after copolymerizing a monomer having a functional group with an acrylic polymer in advance, a compound having a functional group capable of reacting with the functional group and a carbon-carbon double bond is subjected to radiation curability of the carbon-carbon double bond. Examples thereof include a method of condensing or adding reaction while maintaining the above.

Examples of the combination of these functional groups include a carboxylic acid group and an epoxy group, a carboxylic acid group and an aziridyl group, a hydroxyl group and an isocyanate group, and the like. Among these combinations of functional groups, a combination of a hydroxyl group and an isocyanate group is preferable because of the ease of reaction tracking. Further, the functional group may be on either side of the acrylic polymer or the compound as long as the combination of these functional groups produces an acrylic polymer having the carbon-carbon double bond. In the above preferred combination, it is preferable that the acrylic polymer has a hydroxyl group and the compound has an isocyanate group. In this case, examples of the isocyanate compound having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α, and α-dimethylbenzyl isocyanate. Further, as the acrylic polymer, one obtained by copolymerizing the above-exemplified hydroxy group-containing monomer, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, ether compound of diethylene glycol monovinyl ether and the like is used.

In the intrinsic type radiation-curable pressure-sensitive adhesive, the base polymer having a carbon-carbon double bond (particularly an acrylic polymer) can be used alone, but the radiation-curable monomer does not deteriorate the properties. Ingredients and oligomer components can also be blended. The radiation-curable oligomer component or the like is usually in the range of 30 parts by weight, preferably in the range of 0 to 10 parts by weight, based on 100 parts by weight of the base polymer.

The radiation-curable pressure-sensitive adhesive contains a photopolymerization initiator when it is cured by ultraviolet rays or the like. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, and 2-methyl-2-hydroxypropio. Α-Ketol compounds such as phenone and 1-hydroxycyclohexylphenyl ketone; methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1- [4-( Methylthio) -phenyl] -2-morpholinoPropane-1 and other acetophenone compounds; benzoin ethyl ether, benzoin isopropyl ether, anisoin methyl ether and other benzoin ether compounds; benzyldimethyl ketal and other ketal compounds; 2-naphthalene sulfonyl Aromatic sulfonyl chloride compounds such as chloride; photoactive oxime compounds such as 1-phenone-1,1-propandion-2- (o-ethoxycarbonyl) oxime; benzophenone, benzoylbenzoic acid, 3,3'-dimethyl Benzophenone compounds such as -4-methoxybenzophenone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2 , 4-diethylthioxanthone, 2,4-diisopropylthioxanthone and other thioxanson compounds; camphorquinone; halogenated ketone; acylphosphinoxide; acylphosphonate and the like. The blending amount of the photopolymerization initiator is, for example, about 0.05 to 20 parts by weight with respect to 100 parts by weight of the base polymer such as an acrylic polymer constituting the pressure-sensitive adhesive.

Further, as the radiation-curable pressure-sensitive adhesive, for example, a photopolymerizable compound such as an addition-polymerizable compound having two or more unsaturated bonds and an alkoxysilane having an epoxy group disclosed in Japanese Patent Application Laid-Open No. 60-196956. Examples thereof include rubber-based pressure-sensitive adhesives and acrylic-based pressure-sensitive adhesives containing photopolymerization initiators such as carbonyl compounds, organic sulfur compounds, peroxides, amines, and onium salt-based compounds.

If necessary, the radiation-curable pressure-sensitive adhesive layer 2 may contain a compound to be colored by irradiation. By including the compound to be colored by irradiation in the pressure-sensitive adhesive layer 2, only the irradiated portion can be colored. That is, the portion 2a corresponding to the work pasting portion 3a shown in FIG. 1 can be colored. Therefore, it is possible to immediately visually determine whether or not the pressure-sensitive adhesive layer 2 has been irradiated with radiation, it is easy to recognize the work-attached portion 3a, and it is easy to attach the work. Further, when the semiconductor chip is detected by an optical sensor or the like, the detection accuracy is improved, and no malfunction occurs when the semiconductor chip is picked up. The compound to be colored by irradiation is a compound that is colorless or light-colored before irradiation, but becomes colored by irradiation, and examples thereof include leuco dyes. The ratio of the compound to be colored by irradiation can be appropriately set.

The thickness of the pressure-sensitive adhesive layer 2 is not particularly limited, but is preferably about 1 to 50 μm from the viewpoints of preventing chipping of the chip cut surface and compatibility of fixing and holding the heat-bonding sheets 3 and 3'. .. It is preferably 2 to 30 μm, more preferably 5 to 25 μm.

The dicing tape 11 according to the present embodiment is produced, for example, as follows.
First, the base material 1 can be formed by a conventionally known film-forming method. Examples of the film-forming method 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 laminating method.

Next, the pressure-sensitive adhesive composition solution is applied onto the substrate 1 to form a coating film, and then the coating film is dried under predetermined conditions (by heat-crosslinking if necessary) to form the pressure-sensitive adhesive layer 2. Form. The coating method is not particularly limited, and examples thereof include roll coating, screen coating, and gravure coating. The drying conditions are, for example, a drying temperature of 80 to 150 ° C. and a drying time of 0.5 to 5 minutes. Further, the pressure-sensitive adhesive composition may be applied onto the separator to form a coating film, and then the coating film may be dried under the above-mentioned drying conditions to form the pressure-sensitive adhesive layer 2. Then, the pressure-sensitive adhesive layer 2 is bonded onto the base material 1 together with the separator. As a result, the dicing tape 11 is produced.

The heat-bonding sheets 10 and 12 with dicing tape can be manufactured by a usual method. For example, by laminating the pressure-sensitive adhesive layer 2 of the dicing tape 11 and the heat-bonding sheet 3, the heat-bonding sheet 10 with the dicing tape can be manufactured.
In the heat-bonding sheet 10 with dicing tape, it is preferable that the heat-bonding sheet 3 is covered with a separator. For example, after the dicing tape 11 and the heat-bonding sheet 3 are bonded together, the base material separator laminated on the heat-bonding sheet 3 is peeled off, and the front base material separator is peeled off and then heat-bonded with the dicing tape. A method of attaching a separator to the exposed surface of the heat-bonding sheet 3 of the sheet 10 can be mentioned. That is, it is preferable that the dicing tape 11, the heat bonding sheet 3, and the separator are laminated in this order.

In the above-described embodiment, a heat-bonding sheet with a dicing tape in which a dicing tape and a heat-bonding sheet are laminated has been described. However, the heat-bonding sheet of the present invention may be provided in a state where it is not bonded to the dicing tape.
When the dicing tape is not bonded to the heat-bonding sheet, it is preferable to use a heat-bonding sheet with a double-sided separator sandwiched between two separators. That is, it is preferable to use a heat bonding sheet with a double-sided separator in which the first separator, the heat bonding sheet, and the second separator are laminated in this order.
FIG. 3 is a schematic cross-sectional view showing an embodiment of a heat bonding sheet with a double-sided separator.
The heat-bonding sheet 30 with a double-sided separator shown in FIG. 3 has a structure in which the first separator 32, the heat-bonding sheet 3, and the second separator 34 are laminated in this order. As the first separator 32 and the second separator 34, the same ones as the base material separator can be used.
When the dicing tape is not attached to the heat-bonding sheet, the separator may be laminated only on one surface of the heat-bonding sheet.

(Manufacturing method of bonded body)
The method for manufacturing a bonded body according to the present embodiment is as follows.
The process of preparing the heat-bonding sheet and
It includes at least a step of heat-bonding two objects to be bonded via the heat-bonding sheet.
The bonding temperature in the heat bonding step is in the range of 200 to 400 ° C.

Hereinafter, a case where the bonded body of the present invention is a semiconductor device and the bonded object of the present invention is a semiconductor chip and an adherend will be described. However, the object to be bonded in the present invention is not limited to this example as long as it can be bonded using a heat bonding sheet. Further, the bonded body in the present invention may be any as long as it is bonded using a heat bonding sheet, and is not limited to the semiconductor device.

(Manufacturing method of semiconductor device)
The method for manufacturing a semiconductor device according to the present embodiment includes a step of preparing the heat-bonding sheet and a process of preparing the heat-bonding sheet.
The step of heat-bonding the semiconductor chip onto the adherend via the heat-bonding sheet is included without sand.
The bonding temperature in the heat bonding step is in the range of 200 to 400 ° C. (hereinafter, also referred to as the first embodiment).
As described above, the semiconductor chip and the adherend correspond to the adherend of the present invention.

Further, the method for manufacturing the semiconductor device according to the present embodiment includes the step of preparing the heat bonding sheet with the dicing tape described above and the step of preparing the heat bonding sheet with the dicing tape.
A bonding step of bonding the heat bonding sheet of the heat bonding sheet with dicing tape and the back surface of the semiconductor wafer.
A dicing step of dicing the semiconductor wafer together with the heat bonding sheet to form a chip-shaped semiconductor chip.
A pickup step of picking up the semiconductor chip from the heat-bonding sheet with dicing tape together with the heat-bonding sheet.
A heat bonding step of heat-bonding the semiconductor chip onto an adherend via the heat-bonding sheet is included.
The bonding temperature in the heat bonding step is in the range of 200 to 400 ° C. (hereinafter, also referred to as a second embodiment).
As for the method for manufacturing a semiconductor device according to the first embodiment, while the method for manufacturing a semiconductor device according to a second embodiment uses a heat bonding sheet with a dicing tape, the semiconductor according to the first embodiment The manufacturing method of the device differs in that the sheet for heat bonding is used as a single unit, and is common in other points. In the method for manufacturing a semiconductor device according to the first embodiment, if a step of preparing a heat-bonding sheet and then laminating it with a dicing tape is performed, then the method for manufacturing the semiconductor device according to the second embodiment is performed. Can be similar to. Therefore, the method of manufacturing the semiconductor device according to the second embodiment will be described below.

In the method for manufacturing a semiconductor device according to the present embodiment, first, the heat-bonding sheets 10 and 12 with a dicing tape are prepared (preparation step). The heat-bonding sheets 10 and 12 with dicing tape are used as follows by appropriately peeling off a separator arbitrarily provided on the heat-bonding sheets 3 and 3'. Hereinafter, a case where the heat bonding sheet 10 with a dicing tape is used with reference to FIGS. 1 and 4 will be described as an example.

First, the semiconductor wafer 4 is pressure-bonded onto the semiconductor wafer-attached portion 3a of the heat-bonding sheet 3 in the heat-bonding sheet 10 with dicing tape, and the semiconductor wafer 4 is bonded and held to be fixed (bonding step). This step is performed while pressing with a pressing means such as a crimping roll. The attachment temperature at the time of mounting is not particularly limited, and is preferably in the range of, for example, 23 to 90 ° C.

The semiconductor wafer 4 preferably has an electrode pad formed on one surface and a silver thin film formed on the outermost surface of the other surface (hereinafter, also referred to as a back surface). Examples of the thickness of the silver thin film include 10 nm to 1000 nm. Further, a titanium thin film may be further formed between the semiconductor wafer 4 and the silver thin film. Examples of the thickness of the titanium thin film include 10 nm to 1000 nm. When the silver thin film is formed, the semiconductor chip 5 and the heat-bonding sheet 3 can be firmly heat-bonded in the heat-bonding step described later. Further, when the titanium thin film is formed, the reliability of the electrode is improved. The silver thin film and the titanium thin film can be formed, for example, by thin film deposition.

Next, dicing of the semiconductor wafer 4 is performed (dicing step). As a result, the semiconductor wafer 4 is cut into a predetermined size and made into individual pieces to manufacture the semiconductor chip 5. The dicing method is not particularly limited, but is performed according to a conventional method from the circuit surface side of the semiconductor wafer 4, for example. Further, in this step, for example, a cutting method called full cut in which a cut is made up to the heat bonding sheet 10 with a dicing tape can be adopted. The dicing apparatus used in this step is not particularly limited, and conventionally known dicing apparatus can be used. Further, since the semiconductor wafer 4 is adhesively fixed by the heat bonding sheet 10 with a dicing tape, chip chipping and chip skipping can be suppressed, and damage to the semiconductor wafer 4 can also be suppressed.

Next, the semiconductor chip 5 is picked up in order to peel off the semiconductor chip 5 bonded and fixed to the heat bonding sheet 10 with the dicing tape (pickup step). The pickup method is not particularly limited, and various conventionally known methods can be adopted. For example, a method in which each semiconductor chip 5 is pushed up from the side of the heat bonding sheet 10 with a dicing tape by a needle and the pushed-up semiconductor chip 5 is picked up by a pickup device and the like can be mentioned.

As a pickup condition, the needle pushing speed is preferably 5 to 100 mm / sec, and more preferably 5 to 10 mm / sec from the viewpoint of preventing chipping.

Here, when the pressure-sensitive adhesive layer 2 is an ultraviolet curable type, the pickup is performed after the pressure-sensitive adhesive layer 2 is irradiated with ultraviolet rays. As a result, the adhesive force of the pressure-sensitive adhesive layer 2 to the heat-bonding sheet 3 is reduced, and the semiconductor chip 5 can be easily peeled off. As a result, pickup is possible without damaging the semiconductor chip 5. Conditions such as irradiation intensity and irradiation time at the time of ultraviolet irradiation are not particularly limited, and may be appropriately set as necessary. Further, as the light source used for ultraviolet irradiation, a known light source can be used. When the pressure-sensitive adhesive layer is previously irradiated with ultraviolet rays and cured, and the cured pressure-sensitive adhesive layer and the heat-bonding sheet are bonded to each other, the ultraviolet irradiation here is unnecessary.

Next, the semiconductor chip 5 is temporarily bonded to the adherend 6 via the heat bonding sheet 3. The temporary bonding step can be performed using a chip mounter or the like. As the temporary bonding conditions, it is preferable to temporarily bond at a pressure of 0.01 MPa to 5 MPa. The temperature at the time of temporary bonding is not particularly limited, but is preferably in the range of, for example, 23 to 150 ° C. The pressurization time is preferably 0.01 to 5 seconds.

Next, the semiconductor chip 5 is heat-bonded to the adherend 6 via the heat-bonding sheet 3 (heat-bonding step). Examples of the adherend 6 include a lead frame, a TAB film, a substrate, a separately manufactured semiconductor chip, and the like. The adherend 6 may be, for example, a deformable adherend that is easily deformed, or a non-deformable adherend (semiconductor wafer or the like) that is difficult to deform.

Examples of the lead frame include metal lead frames such as Cu lead frames and 42 Alloy lead frames. Further, as the substrate, a conventionally known substrate can be used. For example, an organic substrate made of glass epoxy, BT (bismaleimide-triazine), polyimide or the like can be mentioned. Above all, if a metal lead frame is used, it can be integrated with copper particles by heat bonding. Further, as the substrate, an insulating circuit board in which a copper circuit board is laminated on an insulating substrate such as a ceramic plate can be mentioned. If an insulated circuit board is used, for example, a power semiconductor device that controls and supplies electric power can be manufactured.

In the heat bonding step, the copper particles are sintered by heating and the polycarbonate as a thermally decomposable binder is thermally decomposed. In addition, the residual low boiling point binder that has not been completely volatilized by the drying step is volatilized. The joining temperature can be preferably 200 to 400 ° C, more preferably 190 to 370 ° C, and even more preferably 200 to 350 ° C. The joining time can be preferably 0.3 to 300 minutes, more preferably 0.5 to 240 minutes, and even more preferably 1 to 180 minutes. Further, the heat bonding may be performed under pressurized conditions. The pressurization condition is preferably in a range of 1~500kg / cm ^2, in the range of 5~400kg / cm ² is more preferable. The heat bonding under pressure can be carried out by a device such as a flip chip bonder that can simultaneously heat and pressurize. Further, a parallel flat plate press may be used. The heat bonding step is preferably performed under a nitrogen atmosphere, a reduced pressure, or a reducing gas atmosphere. Copper particles have the property of oxidizing at high temperatures. Further, when the object to be bonded is made of copper, it is oxidized at a high temperature. Therefore, if the step of heat-bonding is performed under a nitrogen atmosphere, a reduced pressure, or a reducing gas atmosphere, oxidation of copper particles and the like due to heating can be prevented.

A temperature raising step may be performed before the heat joining step.
For example, the following steps may be performed after the temporary bonding step.
A temperature raising step of raising the temperature of the laminate having the semiconductor chip 5, the heat bonding sheet 3, and the adherend 6 from the first temperature or lower to the second temperature, and
After the temperature raising step, a step of keeping the temperature of the laminated body within a predetermined range and heat-bonding (heat-bonding step).

The first temperature varies depending on the composition of the presintering layer, and examples thereof include 50 ° C., 80 ° C., 100 ° C. and the like.

In this temperature raising step, for example, one or both of the parallel plates are preheated to the first temperature in advance, the laminate is sandwiched between the parallel plates, and then the temperature is increased at a predetermined temperature. The temperature may be raised to the temperature of 2.

The rate of temperature rise is preferably 0.1 ° C./s or higher, more preferably 0.5 ° C./s or higher, and even more preferably 1 ° C./s or higher. The rate of temperature rise is preferably 5 ° C./s or less, more preferably 3 ° C./s or less, and even more preferably 2 ° C./s or less. When the temperature rising rate is 2 ° C./s or less, rapid heating can be further suppressed. On the other hand, when the temperature rise temperature is 0.1 ° C./s or higher, the process can be shortened.

The second temperature is a temperature at the time when the heat bonding step is started, and is a temperature at which sintering starts substantially.

The second temperature varies depending on the composition of the presintering layer, and examples thereof include 200 ° C., 250 ° C., and 300 ° C.

The laminate 10 may be pressurized while the temperature rises from the temperature below the first temperature to the temperature of the second temperature. The pressurization is preferably in the range of 5 to 40 MPa, more preferably in the range of 5 to 15 MPa. When the pressurization is 5 MPa or more, a stronger bonded body can be obtained. Further, when the pressurization is 40 MPa or less, it is possible to reduce the load on the chip. The pressurization may be a pressurization by a constant pressure, or may be a pressurization while varying the pressure within a constant range.
Further, the pressurization may always pressurize the laminate while the temperature rises from the first temperature or lower to the second temperature, or may pressurize the laminate for at least a part of the period. This is because the bonding becomes more suitable if the pressure is applied for at least a part of the period. For example, the temperature rise may be started from the first temperature or lower without pressurization, and the pressurization may be started after a certain period of time and before reaching the second temperature.

Next, if necessary, as shown in FIG. 4, the tip of the terminal portion (inner lead) of the adherend 6 and the electrode pad (not shown) on the semiconductor chip 5 are electrically connected by the bonding wire 7. (Wire bonding process). As the bonding wire 7, for example, a gold wire, an aluminum wire, a copper wire, or the like is used. The temperature at which wire bonding is performed is in the range of 23 to 300 ° C, preferably 23 to 250 ° C. Moreover, the heating time is several seconds to several minutes. The connection is performed by the combined use of vibration energy by ultrasonic waves and crimping energy by applied pressurization in a state of being heated so as to be within the temperature range.

Next, if necessary, as shown in FIG. 4, the semiconductor chip 5 is sealed with the sealing resin 8 (sealing step). This step is performed to protect the semiconductor chip 5 and the bonding wire 7 mounted on the adherend 6. This step can be performed by molding the sealing resin with a mold. As the sealing resin 8, for example, an epoxy resin is used. The heating temperature at the time of resin sealing is usually 175 ° C. for 60 to 90 seconds, but the present invention is not limited to this, and for example, it can be cured at 165 to 185 ° C. for several minutes. This cures the sealing resin 8. In this encapsulation step, a method of embedding the semiconductor chip 5 in a sheet-shaped encapsulation sheet (see, for example, Japanese Patent Application Laid-Open No. 2013-7028) can also be adopted. In addition to molding the sealing resin with a mold, a gel-sealing type in which silicone gel is poured into a case-type container may be used.

Next, heating is performed as necessary to completely cure the insufficiently cured sealing resin 8 in the sealing step (post-curing step). The heating temperature in this step varies depending on the type of sealing resin, but is, for example, in the range of 165 to 185 ° C., and the heating time is about 0.5 to 8 hours.

The heat-bonding sheet of the present invention and the heat-bonding sheet with dicing tape can also be suitably used when a plurality of semiconductor chips are laminated and three-dimensionally mounted. At this time, the heat-bonding sheet and the spacer may be laminated between the semiconductor chips, or only the heat-bonding sheet may be laminated between the semiconductor chips without laminating the spacer, depending on the manufacturing conditions, applications, and the like. It can be changed as appropriate.
Further, the heat-bonding sheet of the present invention and the heat-bonding sheet with dicing tape are not limited to the uses exemplified above, and can be used for heat-bonding two sheets.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

The components used in the examples will be described.
Copper particles A (average particle size 150 nm, crystallite diameter size 30 nm)
Copper particles B (average particle size 300 nm, crystallite diameter size 30 nm)
Pyrolytic binder A (polypropylene carbonate resin): QPAC40 manufactured by Empourer, solid low boiling point binder B at 23 ° C (terpene alcohol-based binder (terpene chemical company, Telsolve MTPH))
Organic binder C (acrylic resin): MM-2002-1, manufactured by Fujikura Kasei Co., Ltd., solid at 23 ° C. Organic solvent A: Methyl ethyl ketone (MEK)

[Making a sheet for heat bonding]
According to the compounding ratios shown in Table 1, each component and solvent shown in Table 1 were placed in a stirring kettle of a hybrid mixer (HM-500 manufactured by KEYENCE), and stirred and mixed in a stirring mode in 3 minutes.
The obtained varnish was applied to a mold release film (MRA50 manufactured by Mitsubishi Plastics Co., Ltd.) and dried. The drying conditions were 80 ° C. for 2 minutes. As a result, a heat bonding sheet having a thickness of 65 μm according to Examples and Comparative Examples was obtained.

[Reliability evaluation]
A silicon chip (silicon chip thickness 350 μm, length 5 mm, width 5 mm) in which a Ti layer (thickness 50 nm) and an Ag layer (thickness 100 nm) were formed in this order was prepared on the back surface. The heat-bonding sheets of Examples and Comparative Examples were bonded to the Ag layer surface of the prepared silicon chip.
The bonding conditions were a temperature of 70 ° C., a pressure of 0.3 MPa, and a speed of 10 mm / sec.

A copper plate (copper plate thickness 3 mm) completely covered with an Ag layer (thickness 5 μm) was prepared. A heat-bonding sheet with a silicon chip (created above) was temporarily bonded onto the prepared copper plate. The pressure at the time of temporary bonding is 0.1 MPa.

Next, the temperature was raised and the bonding was performed under the following heating conditions.

<Heating conditions>
The temperature was raised from 80 ° C. to 300 ° C. at a heating rate of 1.5 ° C./sec under a pressure of 10 MPa (flat plate press), and then held (joined) at 300 ° C. for 2.5 minutes. The atmosphere at the time of raising the temperature and joining was as shown in Table 1.

Then, it was air-cooled to 170 ° C. and then water-cooled to 80 ° C. The water cooling is based on the water cooling type cooling plate provided in the pressure plate.

Next, the evaluation sample was put into a thermal shock tester (TSE-103ES manufactured by ESPEC CORPORATION), and a thermal shock of −40 ° C. to 200 ° C. was applied for 100 cycles. At this time, the temperature was maintained at −40 ° C. and 200 ° C. for 15 minutes, respectively.

After 100 cycles, an ultrasonic imaging device [SAT] (FineSAT II manufactured by Hitachi Construction Machinery Finetech) was used to take an image to confirm the part where the silicon chip and the copper plate are joined by the sintered layer. rice field. The transducer (probe) used is PQ-50-13: WD [frequency 50 MHz].

In the obtained image, the area (remaining area) of the portion where the bonding remained was obtained, and the ratio of the remaining area to the total area (residual bonding area ratio) was calculated. Further, the case where the residual bonding area ratio was 50% or more was evaluated as ◯, and the case where it was lower than 50% was evaluated as x. The results are shown in Table 1. In the image obtained by the ultrasonic imaging device, the part where the silicon chip and the substrate are peeled off looks white, and the part where the bonding remains looks gray.

1 Base material 2 Adhesive layer 3, 3'Heat bonding sheet 4 Semiconductor wafer 5 Semiconductor chip 6 Adhesion 7 Bonding wire 8 Encapsulating resin 10, 12 Heat bonding sheet with dicing tape 11 Dicing tape 30 Heating with double-sided separator Bonding sheet 31 Pre-sintering layer 32 First separator 34 Second separator

Claims (6)

It has a presintering layer containing copper particles and polycarbonate,
The content of the copper particles is in the range of 60 to 98% by weight with respect to the entire presintering layer.
The average particle size of the copper particles is in the range of 10 to 1000 nm.
The polycarbonate, aliphatic polycarbonate, or, Ri aromatic polycarbonate der,
The polycarbonate is heat-bonding sheet, wherein the polycarbonate der Rukoto capable of thermal decomposition at a heat-bonding temperature of 200 to 400 ° C.. The copper particles are composed of a plurality of crystallites and are composed of a plurality of crystallites.
The heat-bonding sheet according to claim 1, wherein the crystallite diameter of the crystallite is 50 nm or less. With dicing tape,
A heat-bonding sheet with a dicing tape, which comprises the heat-bonding sheet according to claim 1 or 2 laminated on the dicing tape. The step of preparing the heat-bonding sheet according to claim 1 or 2, and
Including a step of heat-bonding two objects to be bonded via the heat-bonding sheet.
A method for producing a bonded body, wherein the bonding temperature in the heat bonding step is in the range of 200 to 400 ° C. The method for producing a bonded body according to claim 4, wherein the heat-bonding step is performed under a nitrogen atmosphere, a reduced pressure, or a reducing gas atmosphere. The heat-bonding sheet according to claim 1 or 2,
A power semiconductor device including a power semiconductor device.

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