JP2015224263A - Adhesive composition, semiconductor device using the same and production method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition which is excellent in dispersibility of silver particles and secures sufficient adhesion strength even when baked in an inert gas, e.g. nitrogen, a semiconductor device using it and a production method of a semiconductor device.SOLUTION: An adhesive composition comprises silver particles, a 6C or higher aliphatic primary amine, formic acid and a dispersion medium, in a combined content of the aliphatic primary amine and formic acid of 0.7-5.0 pts. mass and a content of the dispersion medium of 5-15 pts. mass relative to 100 pts. mass of silver particles and a molar ratio of formic acid to the aliphatic primary amine of 0.5-1.4.

Description

  The present invention relates to an adhesive composition, a semiconductor device using the same, and a method for manufacturing the semiconductor device. More specifically, an adhesive composition suitable for bonding semiconductor elements such as power semiconductors, LSIs, and light emitting diodes (LEDs) to substrates such as lead frames, ceramic wiring boards, glass epoxy wiring boards, polyimide wiring boards, and the like The present invention relates to a semiconductor device using semiconductor and a method for manufacturing the semiconductor device.

  When manufacturing a semiconductor device, a semiconductor element and a lead frame (supporting member) can be bonded to each other by dispersing a filler such as silver powder in a resin such as an epoxy resin or a polyimide resin (for example, silver). As a paste), there is a method of using this as an adhesive. In this method, a paste adhesive is applied to a die pad of a lead frame using a dispenser, a printing machine, a stamping machine, etc., and then a semiconductor element is die-bonded and bonded by heat curing to obtain a semiconductor device.

  In recent years, as semiconductor devices have been increased in speed and integration, high heat dissipation characteristics are required in order to ensure the operational stability of semiconductor devices.

  As means for achieving higher heat dissipation than conventional conductive adhesives utilizing contact between metal particles, an adhesive composition (for example, Patent Documents 1 to 3) that highly fills silver particles with high thermal conductivity, solder An adhesive composition using particles (for example, Patent Document 4) and an adhesive composition using metal nanoparticles having an average particle diameter of 0.1 μm or less that are excellent in sintering properties (for example, Patent Document 5) have been proposed.

  In addition, by using micro-sized silver particles that have been subjected to a special surface treatment, the heating at 100 ° C. or more and 400 ° C. or less is performed as a material having superior thermal conductivity and connection reliability at high temperatures than these compositions. Has proposed an adhesive composition (for example, Patent Document 6) in which silver particles are sintered together. In the sintered silver adhesive composition in which the silver particles proposed in Patent Document 6 are sintered with each other, the silver particles form a metal bond. It is considered that the connection reliability is excellent.

JP 2006-73811 A JP 2006-302834 A JP-A-11-66953 JP 2005-93996 A JP 2006-83377 A Japanese Patent No. 4353380

  By the way, when joining a semiconductor element and a board | substrate with a sintered silver adhesive composition, noble metal plating is given to the adherend surface of a board | substrate for the adhesive improvement with a sintered silver adhesive composition. On the other hand, since the surface on which the noble metal plating is applied is poor in adhesion to the sealing resin, the base material is not subjected to the noble metal plating except for the contact portion with the sintered silver adhesive composition on the substrate. Copper may be exposed. In this case, the substrate is fired in an inert gas such as nitrogen in order to suppress copper oxidation / discoloration. However, in the conventional sintered silver adhesive composition, an organic substance that protects the surface of the silver particles during firing is removed in the air. Since it is removed by oxidative decomposition with oxygen, there is a problem that the oxidative decomposition does not proceed in an inert gas such as nitrogen, the sintering of silver particles is significantly inhibited, and the die shear strength is greatly reduced.

  Moreover, in order to join a semiconductor element and a board | substrate suitably, it is desirable for a silver particle to disperse | distribute in a silver sintering adhesive composition, and to form a silver sintering adhesive composition in paste form.

  The present invention provides an adhesive composition that is excellent in dispersibility of silver particles and can ensure sufficient adhesive strength even when fired in an inert gas such as nitrogen, and a semiconductor device and a method of manufacturing a semiconductor device using the same The purpose is to provide.

  The present invention contains silver particles, an aliphatic primary amine having 6 or more carbon atoms, formic acid, and a dispersion medium, and the total amount of the aliphatic primary amine and formic acid is 0 with respect to 100 parts by weight of the silver particles. .7 parts by mass to 5.0 parts by mass, the content of the dispersion medium is 5 parts by mass to 15 parts by mass, and the molar ratio of formic acid to the aliphatic primary amine is 0.5 to 1.4. An agent composition is provided.

  The Casson viscosity of the adhesive composition is preferably 0.08 Pa · s to 2.9 Pa · s.

  The average particle diameter of the silver particles is preferably 0.05 μm to 50 μm, and the ratio of the flaky silver particles in the silver particles is preferably 50% by mass or more.

  The present invention also provides a semiconductor device having a structure in which a semiconductor element and a semiconductor element mounting support member are bonded via the above-described adhesive composition.

  Moreover, this invention provides the manufacturing method of a semiconductor device provided with the process of baking said adhesive composition at the temperature of 180 degreeC or more in the atmosphere whose oxygen concentration is 0.01 volume% or less.

  According to the present invention, sufficient adhesive force can be ensured even when the adhesive composition is baked in an atmosphere having a low oxygen concentration. Therefore, even when a base metal is contained on the surface of a member such as a substrate, the adhesive composition can be bonded with sufficiently high adhesive force. The adhesive composition which can be provided, the semiconductor device using the same, and the manufacturing method of a semiconductor device can be provided.

2 is a SEM image showing a cross section of a die bond layer after bonding in Example 1. FIG. 4 is a SEM image showing a cross section of a die bond layer after bonding in Comparative Example 1; 4 is a SEM image showing a cross section of a die bond layer after bonding in Comparative Example 2. 10 is a SEM image showing a cross section of a die bond layer after bonding in Comparative Example 4; It is a graph which shows the relationship of the die shear strength after joining with respect to the molar ratio of the additive 1 and the additive 2. FIG. It is a graph which shows the relationship of the die shear strength after joining with respect to the total amount of additive 1 and additive 2 when the molar ratio of additive 1 / additive 2 is 1.

  Hereinafter, preferred embodiments of an adhesive composition according to the present invention, a semiconductor device using the same, and a method for manufacturing the semiconductor device will be described in detail.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when it cannot be clearly distinguished from other processes. .

  In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

  Further, when referring to the amount of each component in the composition in the present specification, when there are a plurality of substances corresponding to each component in the composition, the plurality of the components present in the composition unless otherwise specified. It means the total amount of substance.

<Adhesive composition>
The adhesive composition of this embodiment contains silver particles, an aliphatic primary amine having 6 or more carbon atoms (hereinafter also simply referred to as “aliphatic primary amine”), formic acid, and a dispersion medium.

  In the adhesive composition of the present embodiment, the total amount of the aliphatic primary amine and formic acid is 0.7 parts by mass to 5.0 parts by mass, and 0.75 parts by mass when the silver particles are 100 parts by mass. Part to 3.0 parts by weight, preferably 0.8 part to 2.0 parts by weight. The molar ratio of formic acid to aliphatic primary amine (formic acid / aliphatic primary amine) is 0.5 to 1.4, preferably 0.6 to 1.3, more preferably 0.7 to 1.2. preferable. When the contents of the aliphatic primary amine and formic acid are within the above ranges, the adhesive composition is sintered even in an atmosphere having a low oxygen concentration, so that the semiconductor element and the substrate can be joined without oxidizing the member.

  Moreover, since the adhesive composition is used in the form of a paste, it contains a dispersion medium. Content of a dispersion medium is 5 mass parts-15 mass parts with respect to 100 mass parts of silver particles, 7 mass parts-14 mass parts are preferable, and 8 mass parts-13 mass parts are more preferable.

  The adhesive composition has a Casson viscosity of 0.08 Pa · s to 2.9 Pa · s, preferably 0.08 Pa · s to 2.0 Pa · s, and 0.1 Pa · s to 1.7 Pa · s. Is more preferable. If it is this range, an adhesive composition can be apply | coated or printed uniformly.

The Casson viscosity of the adhesive composition can be measured with a viscoelasticity measuring device (Physica MCR-501, manufactured by Anton Paar). A cone type measuring jig (CP50-1) with an angle of 1 ° and a diameter of 50 mm is mounted, and an adhesive composition overflowing from the measuring jig at the measuring position is introduced into the measuring apparatus, and the measuring jig is set at the measuring position. The measurement is carried out after scraping off the adhesive composition overflowing when lowered. The measurement is performed at 25 ° C., and the following two steps are continuously performed, and the shear rate and the shear stress are recorded in the second step.
(I) Shear rate ^{0 s −1} , 600 seconds,
(Ii) a shear rate of 0 to 100s ^-1, shear rate increase rate ¹⁰⁰ / 60s -1 / step, measurement interval 1 sec, the measurement points 60 points.

  From the obtained shear rate and shear stress, publicly known literature (Technical Information Society: Measurement and Control of Rheology, Answers for each question -Measure rheology and make physical properties naked-, Tokyo, Technical Information Society, 2010, p39. The Casson viscosity is calculated by the method described in -46). Specifically, the square root of each obtained shear rate and shear stress is calculated, and the slope of the straight line approximated by the least square method is calculated from the 1/2 power of the shear stress with respect to the 1/2 power of the shear rate. . The square of this slope is the Casson viscosity.

(Aliphatic primary amine)
The aliphatic primary amine has 6 or more carbon atoms, preferably 9 or more, and more preferably 12 or more. The upper limit of the carbon number of the aliphatic primary amine is not particularly limited, but can be, for example, 26 or less. The number of amino groups of the aliphatic primary amine is preferably 1 to 3, more preferably 1 to 2, and still more preferably 1. Specific examples of the aliphatic primary amine having 6 or more carbon atoms include hexylamine, 2-aminohexane, (3-methylpentyl) amine, 2-amino-3,3-dimethylbutane, and 1-ethyl-1- Methylpropylamine, 3,3-dimethylbutylamine, 1,3-dimethylbutylamine, 1,1-dimethylbutylamine, 1,2-dimethylbutylamine, heptylamine, 1-propylbutylamine, 1,3-dimethylamylamine, 2- Aminoheptane, 2-amino-5-methylhexane, 1,7-heptanediamine, octylamine, 2-aminooctane, 6-methyl-1-heptylamine, 2-ethyl-1-hexylamine, 2-amino-6 -Methylheptane, 1,1,3,3-tetramethylbutylamine, 2-amino-2,4,4-trime Rupentane, 1,8-diaminooctane, cyclooctylamine, nonylamine, 2-aminononane, isononylamine, 3-methyl-1-octaneamine, decylamine, 1,10-diaminodecane, 2-decanamine, miltanylamine, adamantane Amine, undecylamine, 1-methyldecylamine, aminododecane, 1,12-dodecanediamine, aminobicyclohexyl, tridecylamine, tetradecylamine, pentadecylamine, 1-heptyloctylamine, 1-methyltetradecylamine Hexadecylamine, heptadecylamine, stearylamine, oleylamine, nonadecylamine, icosylamine and the like.

(Silver particles)
The silver particles are particles containing silver atoms, and more preferably particles containing silver atoms as a main component (for example, 90% by mass or more, the same applies hereinafter). Examples of the composition mainly composed of silver atoms include metallic silver and silver oxide, with metallic silver being preferred.

  Examples of the shape of the silver particles include a spherical shape, a lump shape, a needle shape, and a flake shape. Here, the needle shape means that the distance between the parallel two planes selected so that the distance between the parallel two planes becomes the maximum among the parallel two planes circumscribing the silver particles is the major axis, and is orthogonal to the parallel two planes that give the major axis. And the distance between the parallel two planes selected so that the distance between the parallel two planes is minimized among the parallel two planes circumscribing the silver particles is perpendicular to the parallel two planes giving the major axis and the silver Among the parallel two planes circumscribing the particles, when the distance between the parallel two planes selected so as to maximize the distance between the parallel two planes is the medium diameter, the major axis is 1 to 50 μm, the aspect ratio (major axis / minor axis and It means the shape of silver particles having a major axis / medium diameter of 3 to 1000. The flaky shape is analyzed from the result of SEM observation of silver particles, and the average thickness t is 0.1 μm to 15 μm, and the aspect ratio (average particle diameter a / average thickness t) is in the range of 3 to 1000. Means the shape. The lump shape means an irregular shape out of a needle shape having an aspect ratio of 3 or less or a non-flap shape. Since the piece-like silver particles are stacked and overlapped, the contact area between the silver particles is increased and the sintering is facilitated, so that the ratio of the piece-like silver particles in the silver particles is 50% by mass or more. Preferably, it is 60 mass% or more, and more preferably 70 mass% or more.

  The average particle size of primary particles of silver particles is preferably 0.02 μm to 50 μm, more preferably 0.05 μm to 30 μm, and further preferably 0.08 μm to 25 μm. When the average particle size is at least the lower limit value, the dispersibility is further improved. When the average particle size is not more than the upper limit value, the die bond layer can have a suitable thickness. The average particle size (volume average particle size) of primary particles of silver particles can be measured by a laser diffraction type particle size distribution measuring device. An example of the measurement method is shown below.

  0.1 g of silver particles, 0.01 g of sodium dodecylbenzenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.) and 9.99 g of distilled water (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed and treated with an ultrasonic cleaner for 5 minutes to produce water. A dispersion was obtained. Using a laser scattering particle size distribution analyzer LS13 320 (manufactured by Beckman Coulter) equipped with a universal liquid module with an ultrasonic dispersion unit, the main unit was turned on for 30 minutes to stabilize the light source, and then distilled to the liquid module. Water is introduced from the measurement program by the Rinse command, and De-bubble, Measurement Offset, Align, and Measurement Background are performed from the measurement program. Subsequently, using Measurement Loading of the measurement program, the aqueous dispersion is shaken and mixed, and when it becomes uniform, it is added to the liquid module using a dropper until the measurement program is changed from the sample amount Low to OK. Thereafter, Measurement is performed from the measurement program to obtain a particle size distribution. As settings of the laser scattering particle size distribution measuring apparatus, Pump Speed: 70%, Include PIDS data: ON, Run Length: 90 seconds, Dispersion medium refractive index: 1.332, Dispersoid refractive index: 0.17-3.4i Using.

  This measurement usually provides a particle size distribution having a plurality of peaks including aggregate peaks in addition to the primary particles. The average particle size of the primary particles is obtained with one of the lowest particle size peaks as the treatment range.

(Dispersion medium)
The dispersion medium may be either organic or inorganic, but preferably has a boiling point of 200 ° C. or higher, more preferably 300 ° C. or higher, from the viewpoint of preventing drying in the coating process. . Also, it preferably has a boiling point of 400 ° C. or lower so that the dispersion medium does not remain after sintering.

  Such dispersion media include terpineol, stearyl alcohol, cetyl alcohol, isobornyl cyclohexanol, tetraethylene glycol, tripropylene glycol methyl ether, diethylene glycol, diethylene glycol monoethyl ether, dipropylene glycol n-propyl ether, dipropylene glycol. Alcohols such as n-butyl ether, tripropylene glycol n-butyl ether, 1,3-butanediol, 1,4-butanediol, p-phenylphenol, propylene glycol phenyl ether; octyl octoate, ethyl myristate, methyl linoleate , Tributyl citrate, tributyrin, benzyl benzoate, butyl stearate, 4-methyl-1,3-dioxolane-2 Esters such as ON, γ-butyrolactone, sulfolane, diprene glycol methyl ether acetate, 2- (2-butoxyethoxy) ethanol, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol monobutyl ether acetate, glycerin triacetate; Ketones such as isophorone; lactams such as N-methylpyrrolidone; nitriles such as phenylacetonitrile; and aliphatics such as octadecane, heptadecane and squalane.

  The adhesive composition of the present embodiment may contain one or more selected from a sintering aid, a wettability improver such as a fluorine-based surfactant, and an antifoaming agent such as silicone oil. Note that the adhesive composition of the present embodiment may contain components other than those listed here.

  If necessary, the adhesive composition of the present embodiment further includes a moisture absorbent such as calcium oxide and magnesium oxide, a nonionic surfactant, an ion trap agent such as an inorganic ion exchanger, and a polymerization inhibitor as appropriate. can do.

  The above-mentioned adhesive composition is a combination of dispersing or dissolving devices such as a stirrer, raky machine, three rolls, planetary mixer, etc., by mixing or dividing the above components all together, heating and mixing as necessary, It can be used as a uniform paste by dissolving, pulverizing and kneading or dispersing.

  The above-mentioned adhesive composition can be cured by heating at 100 to 300 ° C. for 5 seconds to 10 hours, for example.

The volume resistivity of the cured adhesive composition is preferably 1 × 10 ⁻⁴ Ω · cm or less, and the thermal conductivity of the cured adhesive composition is preferably 30 W / m · K or more.

<Method for Manufacturing Semiconductor Device>
The semiconductor device manufacturing method according to the present embodiment preferably includes the following steps.

(A) A step of applying an adhesive composition to a semiconductor element or a semiconductor element mounting support member and bonding the semiconductor element and the semiconductor element mounting support member (hereinafter referred to as “process (A)”),
(B) A step of curing the adhesive composition and bonding the semiconductor element and the semiconductor element mounting support member (hereinafter referred to as “step (B)”).

  A process (A) may have a drying process, after giving adhesive composition.

(Process (A))-Adhesive Composition Application Process-
[Preparation of adhesive composition]
The adhesive composition can be prepared by mixing the above-described silver particles, additives and optional components in a dispersion medium. You may perform a stirring process after mixing. Further, the maximum particle size of the dispersion may be adjusted by filtration.

  The stirring treatment can be performed using a stirrer. Examples of such a stirrer include a rotation / revolution stirrer, a lycra machine, a twin-screw kneader, a triple roll, a planetary mixer, and a thin layer shear disperser.

  Filtration can be performed using a filtration device. Examples of the filter for filtration include a metal mesh, a metal filter, and a nylon mesh.

[Application of adhesive composition]
The adhesive composition layer is formed by applying the adhesive composition on the semiconductor element mounting support member or the semiconductor element. Examples of the application method include coating or printing.

  As a method for applying the adhesive composition, for example, dipping, spray coating, bar coating, die coating, comma coating, slit coating, and applicator can be used.

  As a printing method for printing the adhesive composition, for example, a dispenser, stencil printing, intaglio printing, screen printing, needle dispenser, jet dispenser method can be used.

  As the semiconductor element and the semiconductor element mounting support member according to the present embodiment, a member whose adherend surface is a metal is used. Examples of the metal on the adherend surface include gold, silver, copper, and nickel. Further, among the above, a plurality of materials may be patterned on the substrate.

  The adhesive composition layer formed by the application of the adhesive composition can be appropriately dried from the viewpoint of suppressing fluidization and void generation during curing.

  As the drying method, drying at room temperature, drying by heating, or drying under reduced pressure can be used. For heat drying or vacuum drying, hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device A heater heating device, a steam heating furnace, a hot plate press device, or the like can be used.

  The drying temperature and time are preferably adjusted as appropriate according to the type and amount of the dispersion medium used, and are preferably dried at 50 to 180 ° C. for 1 to 120 minutes, for example.

  After the formation of the adhesive composition layer, the semiconductor element and the semiconductor element mounting support member are bonded together via the adhesive composition. When the process (A) includes a drying process, the drying process may be performed at any stage before or after the bonding process.

(Process (B))-Curing treatment-
Next, the adhesive composition layer is cured by firing. Firing of the adhesive composition layer may be performed by heat treatment or heat and pressure treatment. For heat treatment, hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device, heater heating An apparatus, a steam heating furnace, or the like can be used. Moreover, a hot plate press apparatus etc. may be used for a heat pressurizing process, and the above-mentioned heat processing may be performed, putting a weight and pressurizing. The heating temperature in firing the adhesive composition layer is 180 ° C. or higher, preferably 190 ° C. or higher, more preferably 200 ° C. or higher. The upper limit of the heating temperature is not particularly limited, but is, for example, 350 ° C. or less.

  In the manufacturing method according to the present embodiment, the firing of the adhesive composition layer may be performed in the presence or absence of oxygen gas. According to the adhesive composition according to the present embodiment, sufficient adhesive strength can be ensured even in an atmosphere having a low oxygen concentration. Therefore, the firing of the adhesive composition layer is performed, for example, with an oxygen concentration of 0.01 vol%. The following atmosphere may be used.

  A semiconductor in which a semiconductor element and a support member for mounting a semiconductor element are bonded by a cured adhesive composition having excellent adhesiveness, high thermal conductivity, and high heat resistance by the method for manufacturing an adhesive composition of the present embodiment. The device can be manufactured.

<Semiconductor device>
The semiconductor device according to the present embodiment has a structure in which a semiconductor element and a semiconductor element mounting support member semiconductor element are bonded via the adhesive composition according to the present embodiment. Examples of semiconductor devices include diodes, rectifiers, thyristors, MOS gate drivers, power switches, power MOSFETs, IGBTs, Schottky diodes, fast recovery diodes, and other power modules, transmitters, amplifiers, LED modules, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

  Measurement of each characteristic in each example was performed as follows.

(1) Measurement of Casson viscosity Using a viscoelasticity measuring device (Physica MCR-501, manufactured by Anton Paar) connected to a constant temperature water circulation device set at 20 ° C., initialization is performed after startup, and cone type measurement with an angle of 1 ° and a diameter of 50 mm is performed. The jig (CP50-1) was mounted and the zero gap was measured in this order. Thereafter, the measurement position was set to 1 mm, and the motor was adjusted for a long time. After setting the measurement position to 80 mm, raise the measurement jig to the measurement position, introduce an adhesive composition that overflows from the measurement jig into the measurement device, and overflow the adhesive when the measurement jig is lowered to the measurement position The agent composition was scraped off. The measurement was performed at 25 ° C. and the following two steps were continuously performed, and the shear rate and shear stress were recorded in the second step.
(I) Shear rate ^{0 s −1} , 600 seconds,
(Ii) a shear rate of 0 to 100s ^-1, shear rate increase rate ¹⁰⁰ / 60s -1 / step, measurement interval 1 sec, the measurement points 60 points.

  The obtained shear rate and the square root of the shear stress were calculated, and the slope of the straight line approximated by the least square method was calculated from the 1/2 power of the shear stress to the 1/2 power of the shear rate. The value obtained by squaring this slope was defined as the Casson viscosity.

(2) Die shear strength The adhesive composition was applied on a silver-plated PPF-Cu lead frame (land part: 10 × 5 mm) using pointed tweezers. On the applied adhesive composition, a 2 × 2 mm ² Cu chip on which the silver-plated surface was silver-plated was placed and lightly pressed with tweezers. The sample was set on a transfer tray of a fluxless reflow apparatus (Ayumi Kogyo), and the anterior chamber was sealed. After flowing nitrogen in the front chamber for 10 minutes and replacing with nitrogen, the pressure was reduced to 10 Pa or less in advance, and then nitrogen was introduced and transferred to the processing chamber where nitrogen was replaced. In the treatment chamber, the transfer tray was heated from room temperature to 250 ° C. over 20 minutes using a built-in carbon heater under the conditions of atmospheric pressure and nitrogen flow rate of 10 L / min, and heated at 250 ° C. for 1 hour. Thereafter, the transport tray was returned to the front chamber, cooled in nitrogen on a cooling plate until it became 50 ° C. or lower, and then the front chamber was opened and the sample was taken out from the apparatus to obtain a cured sample of the adhesive composition. The adhesive strength of the cured sample of the adhesive composition was evaluated by die shear strength. Using a universal bond tester (4000 series, manufactured by DAGE) equipped with a 1 kN load cell, measure the die shear strength of the cured adhesive composition by pressing the Cu chip horizontally at a measurement speed of 500 μm / s and a measurement height of 100 μm. did. The average of 9 measurements was taken as the die shear strength. Note that when the die shear strength is less than 20 MPa, it can be said that adhesion is poor.

(3) Cross-sectional SEM observation A cured sample of the adhesive composition was prepared in the same manner as in “(2) Die shear strength”. A cured sample of the adhesive composition is fixed in a cup with a sample clip (Sampklip I, manufactured by Buehler), and an epoxy casting resin (Epomount, manufactured by Refinetech) is poured into the cup until the entire sample is filled, and the vacuum desiccator is filled. And deaerated under reduced pressure for 30 seconds. Thereafter, the epoxy casting resin was cured by leaving it at room temperature for 8 hours or more.

  A cross section was cut out to a bonded portion with a polishing apparatus (Refine Polisher HV, manufactured by Refinetech) equipped with water-resistant abrasive paper (Carbo Mac paper, manufactured by Refinetech). Thereafter, the cross section was smoothed with a polishing apparatus in which a buffing cloth dyed with a buffing abrasive was set. The cross section of the cured adhesive composition was observed at an overvoltage of 15 kV for this SEM sample using an SEM apparatus (TM-1000, manufactured by Hitachi, Ltd.). The SEM images for Example 1 and Comparative Examples 1, 2, and 4 are shown in FIGS.

[Example 1, Comparative Examples 1-6]
(Preparation of adhesive composition)
In a 20 mL polyethylene bottle, 0.85 parts by mass (0.156 g) of stearylamine (manufactured by Wako Pure Chemical Industries) and 8.9 parts by mass (1.62 g) of terpineol (alpha terpineol isomer mixed, manufactured by Wako Pure Chemical Industries) The solution was weighed, sealed, and dissolved in a 50 ° C. water bath for 30 minutes. In this solution, 0.15 parts by mass (0.07 g) of formic acid (special grade reagent, manufactured by Wako Pure Chemical Industries), 75 parts by mass of silver particles 1 (LM1, manufactured by Toxen Industries, flakes, average particle size: 1.2 μm) (13.65 g), 25 parts by weight (4.55 g) of silver particles 2 (AGC239, manufactured by Fukuda Metal Foil Powder Industry, flakes, average particle size: 5.4 μm) are weighed and mixed, and dry powder disappears with a spatula The mixture was stirred until sealed, and stirred at 2000 rpm for 1 minute using a rotation / revolution type stirring apparatus (Planetary Vacuum Mixer ARV-310, manufactured by Sinky). A nylon mesh (bolting cloth N-No. 355T) was bent and stretched on the opening of a 20 ml polyethylene bottle, the mixture was put on the mesh, and the inner lid and outer lid were closed. This wide-mouthed polyethylene bottle was placed on a rotation / revolution type stirring apparatus at 1000 rpm for 2 minutes, and the one that passed through the mesh was used as the adhesive composition.

  Using the adhesive composition, each of the above characteristics was measured. The results are shown in Tables 1 and 2. In Comparative Example 1 in which stearic acid was added as an additive, an adhesive strength of 31 MPa was obtained when the die shear strength was measured in the same manner as “(2) Die shear strength” except that firing was performed in air. In this case, adhesion was poor at 7 MPa. On the other hand, in Example 1, adhesive force (die shear strength of 34 MPa) was obtained even when baked in nitrogen. The adhesive composition of Example 1 was found to have a die shear strength of 45 MPa when fired in air, and to obtain adhesive strength in air or in a low oxygen concentration atmosphere.

  In the adhesive composition of Example 1, both stearylamine and formic acid are added as additives. On the other hand, in Comparative Example 2, when only stearylamine was added as an additive, the die shear strength was 18 MPa, which was better than Comparative Example 1, but resulted in poor adhesion. The die shear strengths of Comparative Example 5 and Comparative Example 6 in which the addition amount of stearylamine is changed to 0.5 parts by mass and 2 parts by mass are 11 MPa and 17 MPa, respectively. Adhesive strength was not obtained.

  Further, in Comparative Example 3 in which only formic acid was used as an additive, silver particles were aggregated to form a solid and could not be pasted. Aggregation also occurred in Comparative Example 4 in which the amount of formic acid added was reduced, but a cured sample of the adhesive composition could be produced by increasing the amount of the dispersion medium. The die shear strength of Comparative Example 4 was 10 MPa, indicating poor adhesion.

  From the above, it has been found that by adding both stearylamine and formic acid as additives, a paste can be prepared without agglomerating silver particles and can be fired even in a low oxygen concentration atmosphere.

[Example 2, Comparative Examples 7 to 9]
In order to clarify the influence of the ratio of the additive formic acid and stearylamine, the adhesive composition was prepared and evaluated in the same manner as in Example 1 except that the composition of the adhesive composition was as shown in Table 3. It was. The total amount of additive 1 and additive 2 was 1 part by mass with respect to 100 parts by mass of silver particles. In Comparative Examples 7 to 9 in which the amount of formic acid added was large (additive 1 / additive 2 molar ratio was 1.5 or more), aggregation of silver particles occurred, and the viscosity could not be measured. In particular, when the additive 1 / additive 2 molar ratio was 2 or more, aggregation became remarkable and it was difficult to prepare a paste-like adhesive composition.

  FIG. 5 shows the relationship between the die shear strength and the molar ratio of formic acid and stearylamine. The die shear strength tended to be maximized when the molar ratio was about 1, and was good when the molar ratio was between 0.5 and 4.

[Example 3, Comparative Example 10]
In order to clarify the influence of the additive amount, the total amount of additive 1 and additive 2 was changed. The adhesive composition was prepared and evaluated in the same manner as in Example 1 except that the composition of the adhesive composition was as shown in Table 4. The additive 1 / additive 2 molar ratio was 1.

  When the total amount of additive 1 and additive 2 was 2 parts by mass with respect to 100 parts by mass of silver particles, no significant increase in viscosity of the adhesive composition occurred. The relationship of the die shear strength with respect to the total amount of the additive 1 and the additive 2 is shown in FIG. As the total amount of additive 1 and additive 2 increased to 0, 0.5, and 1 part by mass, the die shear strength increased to 7, 18, and 34 MPa, respectively. When the total amount of additive 1 and additive 2 was 2 parts by mass, it was 29 MPa, which was slightly lower than when the total amount was 1 part by mass. It turned out that the total amount of the additive 1 and the additive 2 should just be 0.7 mass parts or more with respect to 100 mass parts of silver particles from FIG.

[Example 4]
An adhesive composition was prepared in the same manner as in Example 1 except that the additive 2 was changed from stearylamine to dodecylamine (manufactured by Wako Pure Chemical Industries), and each characteristic was measured. The composition and properties of the adhesive composition are shown in Table 5.

[Example 5]
An adhesive composition was prepared in the same manner as in Example 1 except that the additive 2 was changed from stearylamine to hexylamine (manufactured by Wako Pure Chemical Industries), and each characteristic was measured. The composition and properties of the adhesive composition are shown in Table 5.

[Comparative Example 11]
An adhesive composition was prepared in the same manner as in Example 1 except that the additive 2 was changed from stearylamine to triethylamine (manufactured by Wako Pure Chemical Industries), and each characteristic was measured. The composition and properties of the adhesive composition are shown in Table 5.

  From Example 1, Example 4, Example 5, and Comparative Example 11, when using aliphatic primary amines such as stearylamine, dodecylamine, and hexylamine, a die shear strength of 20 MPa or more was obtained. Certain aliphatic primary amines have been found to be suitable. On the other hand, when triethylamine was used, the die shear strength was 19 MPa, and the adhesive composition was unsuitable because it agglomerated and was poor in dispersibility.

[Comparative Example 12]
An adhesive composition was prepared in the same manner as in Example 1 except that the additive 1 was changed from formic acid to acetic acid (manufactured by Wako Pure Chemical Industries), and each characteristic was measured. The composition and properties of the adhesive composition are shown in Table 5. When additive 1 was acetic acid, the die shear strength was 19 MPa, which was less than 20 MPa. From this result, it was found that formic acid is preferable.

Claims (5)

Silver particles, an aliphatic primary amine having 6 or more carbon atoms, formic acid, and a dispersion medium,
The total amount of the aliphatic primary amine and the formic acid is 0.7 parts by mass to 5.0 parts by mass with respect to 100 parts by mass of the silver particles, and the content of the dispersion medium is 5 parts by mass to 15 parts by mass. And
The adhesive composition wherein the molar ratio of the formic acid to the aliphatic primary amine is 0.5 to 1.4.   The adhesive composition according to claim 1, wherein the Casson viscosity is 0.08 Pa · s to 2.9 Pa · s. The average particle diameter of the silver particles is 0.02 μm to 50 μm,
The adhesive composition according to claim 1 or 2, wherein a ratio of the flaky silver particles in the silver particles is 50% by mass or more.   A semiconductor device having a structure in which a semiconductor element and a semiconductor element mounting support member are bonded via the adhesive composition according to claim 1. The manufacturing method of a semiconductor device provided with the process of baking the adhesive composition as described in any one of Claims 1-3 at the temperature of 180 degreeC or more in the atmosphere whose oxygen concentration is 0.01 volume% or less.