Composition, electronic component, and semiconductor device

Abstract

This composition contains (A) Ga or a Ga alloy, (B) a thermally conductive ceramic filler, and (C) a metal powder having a melting point of 900°C or higher.　The present invention makes it possible to provide a composition that contains gallium (Ga) or a Ga alloy and a thermally conductive ceramic filler, the composition having exceptional operability and workability.

Description

Composition, Electronic Component, and Semiconductor Device

[0001] The present invention relates to a composition containing a liquid metal and a thermally conductive ceramic filler, and an electronic component and a semiconductor device including the composition.

[0002] With the high functionality and high performance of electronic devices, the miniaturization and high density of electronic components have been progressing. Therefore, it is important to more efficiently dissipate the heat generated from electronic components.

[0003] For example, in order to efficiently dissipate the heat generated from electronic components, a thermal interface material is used. A thermal interface material is a material for relaxing the thermal resistance of a path for escaping the heat generated from a semiconductor element to a heat sink or a housing, etc., and various forms such as sheets, gels, and greases are used. As the thermal interface material, a composition in which a thermally conductive filler such as a metal filler or a ceramic filler is filled in a silicone resin or an epoxy resin is known.

[0004] For example, in Patent Document 1, an invention related to a thermally conductive silicone composition containing an organopolysiloxane having a kinematic viscosity at 25°C of 10 to 500,000 mm ,

[0006] / s, a thermally conductive filler having an average particle size of 0.01 to 100 μm, gallium or a gallium alloy having a melting point of -20 to 100°C, and an alkoxysilane compound having a specific structure is disclosed. The thermally conductive filler described in Patent Document 1 is specifically zinc oxide, alumina, boron nitride, aluminum nitride, aluminum hydroxide, magnesium oxide, etc., and the thermally conductive filler and gallium or a gallium alloy mainly play a role in improving the thermal conductivity of the silicone composition.

[0005] Japanese Patent Application Laid-Open No. 2023-160267

[0006] In recent years, electronic components have become smaller and more densely packed, requiring superior heat dissipation and thus demanding thermal interface materials with high thermal conductivity. While the thermally conductive silicone composition described in Patent Document 1 above possesses a certain degree of heat dissipation, it is difficult to significantly improve its thermal conductivity because its matrix is ​​an organic silicone resin.

[0007] Gallium (Ga) or gallium alloys, also known as liquid metals, have a relatively low melting point, excellent workability, and a certain thermal conductivity. However, it is difficult to create a material with excellent heat dissipation using only gallium or gallium alloys. Furthermore, because gallium or gallium alloys are in a low-viscosity liquid state at high temperatures, there is a possibility of leakage from the application site, raising reliability issues.

[0008] Therefore, the inventors investigated compositions containing Ga or a Ga alloy and a thermally conductive ceramic filler. However, it was found that simply using a thermally conductive ceramic filler resulted in reduced fluidity of the composition, preventing it from becoming a homogeneous paste, and causing separation of the matrix and filler, leading to poor handling and workability. Against this backdrop, the object of the present invention is to provide a composition containing Ga or a Ga alloy and a thermally conductive ceramic filler that offers excellent handling and workability.

[0009] The inventors diligently conducted research to achieve the above objective. As a result, they discovered that the above problem can be solved by adding a metal powder with a melting point of 900°C or higher to a composition containing Ga or a Ga alloy and a thermally conductive ceramic filler, and thus completed the present invention.

[0010] In other words, the present invention is a composition comprising (A) Ga or a Ga alloy, (B) a thermally conductive ceramic filler, and (C) a metal powder having a melting point of 900°C or higher.

[0011] The (C) metal powder having a melting point of 900°C or higher preferably contains transition metals belonging to the fourth and fifth periods. The (B) thermally conductive ceramic filler filling rate is preferably 25 to 70 volume%. Furthermore, the (C) metal powder having a melting point of 900°C or higher filling rate is preferably 1 to 20 volume%.

[0012] Furthermore, the present invention can include an electronic component containing the above-mentioned composition. Moreover, the present invention can include a semiconductor device containing the above-mentioned composition.

[0013] The present invention makes it possible to provide a composition containing Ga (gallium) or a Ga alloy and a thermally conductive ceramic filler that exhibits excellent fluidity.

[0014] Hereinafter, an example of an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below, and can be modified and implemented as such without departing from the spirit of the invention.

[0015] (A) Ga or Ga alloy The composition of the present invention comprises (A) Ga or a Ga alloy. The Ga alloy can be used without particular limitation as long as it contains Ga. Since (A) Ga or a Ga alloy has a higher thermal conductivity than resin, the thermal conductivity of the composition can be increased compared to conventional compositions in which a thermally conductive ceramic filler such as aluminum nitride is filled into a resin.

[0016] (A) The melting point of Ga or Ga alloy is not particularly limited, but is preferably -25 to 60°C, and more preferably -20 to 40°C. When the melting point of Ga or Ga alloy is within the above range, it melts easily when preparing a composition with a thermally conductive ceramic filler, thus improving workability.

[0017] Ga is metallic gallium, and its melting point is 28-30°C. The melting point of Ga alloys can be adjusted by their composition. The melting point can be determined, for example, by differential scanning calorimetry (DSC).

[0018] (A) Among Ga or Ga alloys, Ga alloys are preferred from the viewpoint of having a low melting point and improving the fluidity of the composition. A Ga alloy is an alloy of Ga and another metal other than Ga. The other metal is not particularly limited, but examples include one or more metals selected from the group consisting of In (indium), Sn (tin), Zn (zinc), and Bi (bismuth). Examples of Ga alloys include Ga-In (gallium-indium alloy), Ga-In-Sn (gallium-indium-tin alloy), Ga-Sn-Zn (gallium-tin-zinc alloy), and Ga-In-Bi-Sn (gallium-indium-bismuth-tin alloy). Among these, Ga-In-Sn (gallium-indium-tin alloy) is preferred from the viewpoint of availability. The proportion of Ga in the Ga alloy is not particularly limited and can be adjusted as appropriate from the viewpoint of adjusting the melting point and thermal conductivity of the Ga alloy, but for example it is 5% by mass or more, preferably 30% by mass or more, and more preferably 50% by mass or more.

[0019] The amount of (A)Ga or Ga alloy in the composition of the present invention is not particularly limited, but is preferably 25% by volume or more and 70% by volume or less, and more preferably 35% by volume or more and 60% by volume or less. By keeping the amount of (A)Ga or Ga alloy within these ranges, a composition that combines good fluidity and high thermal conductivity can be obtained.

[0020] (B) Thermally conductive ceramic filler The composition of the present invention comprises (B) thermally conductive ceramic filler. Since (B) thermally conductive ceramic filler has high thermal conductivity, the composition containing said thermally conductive ceramic filler has excellent heat dissipation properties.

[0021] (B) Known thermally conductive ceramic fillers can be used, such as aluminum nitride, boron nitride, silicon nitride, aluminum oxide (alumina), magnesium oxide, zinc oxide, silica, silicon carbide, and diamond. Among these, aluminum nitride, boron nitride, alumina, zinc oxide, silicon carbide, and diamond are preferred, with aluminum nitride and diamond being particularly preferred. Commercially available thermally conductive ceramic fillers can be used without any particular limitations. In addition, multiple types of thermally conductive ceramic fillers can be used in combination.

[0022] (B) The lower limit of D50 for the thermally conductive ceramic filler is not particularly limited, but is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. When D50 is above these lower limits, it becomes easier to increase the thermal conductivity of the composition. (B) The upper limit of D50 for the thermally conductive ceramic filler is not particularly limited, but is preferably 150 μm or less, more preferably 125 μm or less, and even more preferably 100 μm or less. When D50 is below these upper limits, it becomes easier to use the composition as a thin thermal interface material.

[0023] In this specification, D50 is the particle size at which the volume accumulation in the particle size distribution curve obtained by laser diffraction and scattering is 50%. D50 can be determined, for example, by obtaining a solution in which a thermally conductive ceramic filler is dispersed as a sample, measuring the particle size distribution of the sample using a laser diffraction particle size distribution analyzer, and obtaining the particle size distribution curve from the result.

[0024] The filling rate of (B) thermally conductive ceramic filler in the composition of the present invention is not particularly limited, but from the viewpoint of improving the fluidity of the composition and the thermal conductivity of the composition, it is preferably 25% to 70% by volume, and more preferably 35% to 60% by volume, relative to the whole composition.

[0025] (C) Metal powder with a melting point of 900°C or higher. The composition of the present invention contains (C) metal powder with a melting point of 900°C or higher. By including such metal powder, a composition with excellent fluidity can be obtained. The reason for this is not clear, but the inventors believe it to be as follows. Note that the present invention is not limited to the following.

[0026] (A) Ga or Ga alloys have high interfacial tension, resulting in poor wettability to the surface of (B) thermally conductive ceramic fillers. Therefore, even if (A) Ga or Ga alloys and (B) thermally conductive ceramic fillers are mixed, they do not blend well, and it is difficult to obtain a composition with excellent fluidity. On the other hand, metal powders are easily wetted because they are metals. Therefore, when metal powders are added to (A) Ga or Ga alloys, the viscosity of (A) Ga or Ga alloys increases, the interfacial tension decreases, the wettability to the surface of (B) thermally conductive ceramic fillers improves, and fluidity is improved, which is thought to prevent the separation of (A) Ga or Ga alloys and (B) thermally conductive ceramic fillers when shear force is applied.

[0027] Here, (A) Ga or Ga alloys have low melting points, are easily mixed with other metals, and readily undergo alloying. In particular, alloying readily occurs with metals with low melting points. For example, In, Sn, Zn, and Bi are metals with low melting points of 500°C or less, and readily dissolve in (A) Ga or Ga alloys to form alloys. Furthermore, with metals with low melting points, the grain boundaries tend to be unstable, so Ga easily diffuses and erodes into the metal lattice, and alloying readily proceeds from within the metal. For example, Ga erodes the grain boundaries of Al (aluminum), making Al brittle, thus easily forming an alloy. This alloying adversely affects the fluidity of the composition, so even if metal powders with low melting points are used, it is not possible to obtain a composition with excellent fluidity. On the other hand, if (C) a metal powder has a melting point of 900°C or higher, it is difficult to form an alloy with (A) Ga or a Ga alloy. Therefore, it is presumed that it is possible to improve the compatibility between (A) Ga or a Ga alloy and (B) a thermally conductive ceramic filler while avoiding the aforementioned adverse effects, thereby providing a composition with excellent fluidity.

[0028] (C) Metal powders with a melting point of 900°C or higher are preferably transition metals belonging to the fourth and fifth periods. Transition metals belonging to the fourth and fifth periods have d-orbital electrons, which are also distributed in the outer s-orbitals. Due to this property of having a large number of electrons widely distributed, many electrons are involved in metallic bonding, contributing to an increase in bonding strength, and therefore transition metals belonging to the fourth and fifth periods exhibit higher melting points than typical metals. In fact, all transition metals belonging to the fourth and fifth periods have a melting point of 900°C or higher. In this specification, transition metals belonging to the fourth and fifth periods refer to metals from group 3 to group 11 belonging to the fourth and fifth periods, and include scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, and silver. In the present invention, from the viewpoint of availability, (C) the metal powder having a melting point of 900°C or higher preferably contains titanium, chromium, manganese, iron, cobalt, nickel, copper, niobium, molybdenum, and silver, and particularly preferably contains chromium, nickel, copper, and silver.

[0029] (C) As the metal powder having a melting point of 900°C or higher, commercially available powders can be used without any particular restrictions. In addition, multiple types of metal powders can be used in combination. Furthermore, an alloy consisting of two or more metals may also be used. Particularly preferred are chromium powder, nickel powder, copper powder, and silver powder.

[0030] (C) For metal powders with a melting point of 900°C or higher, the upper limit of the melting point is not particularly limited, but it can be, for example, 3000°C or lower.

[0031] (C) The particle size of the metal powder having a melting point of 900°C or higher is not particularly limited, but is preferably 0.1 μm to 200 μm, more preferably 0.5 μm to 175 μm, and even more preferably 1 μm to 150 μm. When the particle size is within these ranges, it is easy to obtain a composition with good fluidity.

[0032] In this specification, particle size refers to the major axis of a particle observed in a scanning electron microscope image taken at 500x magnification. The particle size is defined as the major axis of the particles that account for 90% of the cumulative total of the particles with the smallest major axis, obtained by observing 100 or more particles and measuring the major axis of each particle.

[0033] The filling ratio of (C) metal powder having a melting point of 900°C or higher in the composition of the present invention is not particularly limited, but from the viewpoint of improving the fluidity of the composition and the thermal conductivity of the composition, it is preferably 1% to 20% by volume, and more preferably 2% to 10% by volume, relative to the whole composition.

[0034] (Other components) The composition of the present invention may contain components other than (A) Ga or Ga alloy, (B) thermally conductive ceramic filler, and (C) metal powder with a melting point of 900°C or higher, to the extent that they do not impair the effects of the present invention. Examples of other components include dispersants, antioxidants, and colorants.

[0035] Furthermore, the composition of the present invention may contain organic substances such as silicone resins and epoxy resins, but from the viewpoint of improving the thermal conductivity and fluidity of the composition, it is preferable to keep the amount of organic substances as small as possible. The amount of organic substances in the composition of the present invention is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass.

[0036] Furthermore, the composition of the present invention may contain metal powder having a melting point of less than 900°C. However, as described above, low-melting-point metal powder may form an alloy with (A)Ga or a Ga alloy, making it difficult to improve fluidity, and the formation of the alloy may progress over time, potentially reducing the storage stability of the composition. For this reason, in the composition of the present invention, the content of metal powder having a melting point of less than 900°C is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass.

[0037] (Thermal Conductivity of the Composition) Unlike conventional materials that use resins such as silicone resins as a matrix, the composition of the present invention uses Ga or a Ga alloy as its matrix, and therefore exhibits excellent thermal conductivity. Furthermore, because it has good fluidity, when the composition of the present invention is used as a thermal interface material in the manufacture of electronic components or semiconductor devices, for example, the matrix (Ga or Ga alloy) and filler are less likely to separate due to shear forces applied during manufacturing, making it easier to achieve high thermal conductivity. The thermal conductivity of the composition of the present invention is, for example, 30 W / (m·K) or higher. The upper limit of the thermal conductivity is not particularly limited, but it can be, for example, 150 W / (m·K) or lower. The thermal conductivity can be measured by the method described in the examples.

[0038] (Method for Manufacturing the Composition) The method for manufacturing the composition of the present invention is not particularly limited and can be manufactured by mixing each component using known methods with various kneaders. When mixing, each component may be added to the kneader and mixed simultaneously, or each component may be added to the kneader and mixed sequentially. The order of addition is not particularly limited. Furthermore, the mixing may be carried out under heating (for example, 40 to 150°C) or under an adjusted atmosphere such as an inert gas atmosphere, if necessary.

[0039] (Form of composition) The composition of the present invention is preferably in the form of a paste or liquid at room temperature (25°C) for easy use.

[0040] (Uses of the composition) The composition of the present invention has high fluidity and can maintain paste-like properties even when the filling rate of thermally conductive ceramic fillers is increased, resulting in good workability. Furthermore, because the composition of the present invention has high thermal conductivity, it can be suitably used as a thermal interface material with excellent heat dissipation properties in various electronic components and semiconductor devices.

[0041] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The various materials used and the conditions for measuring their physical properties are described below.

[0042] (A) Ga or Ga alloy・A-1: Ga-In-Sn (gallium-indium-tin alloy, composition (mass%): Ga / In / Sn = 62 / 25 / 13, manufactured by Kojundo Chemical Laboratory Co., Ltd., melting point: 5°C)

[0043] (B) Thermally conductive ceramic filler・B-1: Aluminum nitride (manufactured by Tokuyama Corporation, D50: 18 μm) ・B-2: Aluminum nitride (manufactured by Tokuyama Corporation, D50: 30 μm) ・B-3: Amorphous diamond (manufactured by Tomei Diamond Co., Ltd., D50: 25 μm) ・B-4: Octahedral diamond (manufactured by Tomei Diamond Co., Ltd., D50: 28 μm)

[0044] (C) Metal powder with a melting point of 900°C or higher・C-1: Chromium powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: 10 μm) ・C-2: Chromium powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: <63 μm) ・C-3: Nickel powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: 2 - 3 μm) ・C-4: Nickel powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: <75 μm) ・C-5: Nickel powder (manufactured by Aldrich, particle size: <150 μm) ・C-6: Copper powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: 1 μm) ・C-7: Copper powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: <45 μm) ・C-8: Copper powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: <75 μm) ・C-9: Silver powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: 1 μm) ・C-10: Silver powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: <45 μm) ・C-11: Silver powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: <75 μm) In all metal powders, it has been confirmed that the particle size is 1 μm or more.

[0045] <Measurement of Thermal Conductivity>The composition prepared in each example and comparative example was applied onto a silicon chip measuring 10 mm × 10 mm. Another silicon chip measuring 10 mm × 10 mm was overlaid thereon to sandwich the composition between the two silicon chips. A sample was obtained by squeezing it with a force of 50 N for 60 seconds using a push-pull gauge (manufactured by IMADA, SVH-1000N). Subsequently, the thickness of the said sample was measured using a micrometer (manufactured by Mitutoyo, high-precision digital micrometer MDH-25MB). Thereafter, the thickness of the silicon chip measured in advance was subtracted from the thickness of the obtained sample to calculate the thickness of only the composition in the sample. Using this sample, the thermal conductivity at 25°C was measured by the laser flash method (manufactured by NETZSCH, LFA467 HyperFlash). The value obtained by subtracting the thermal conductivity of the silicon chip measured in advance was taken as the thermal conductivity of the composition.

[0046] <Evaluation of the Handling Property of the Compound>The behavior when the composition (compound) prepared in each example and comparative example was sandwiched in an amount of about the size of a grain of rice between slide glasses measuring 76 mm × 26 mm × 1 mm and sheared and stretched was observed, and the handling property of the compound was evaluated according to the following criteria. A: The filler does not separate and extends as a homogeneous paste. B: The filler separates and part of it becomes powdery, showing a non-uniform state.

[0047] <Example 1>A composition was obtained by mixing (A) 50% by volume of A-1 as Ga or a Ga alloy, (B) 48% by volume of B-1 as a thermally conductive ceramic filler, and (C) 2% by volume of C-1 as metal powder. The evaluation results of the handling property and thermal conductivity of the said composition are shown in Table 1.

[0048] <Examples 2 to 16, Comparative Examples 1 to 4>Compositions were obtained in the same manner as in Example 1, except that the blending amounts of each component were changed as shown in Tables 1 and 2. The evaluation results of the handling property and thermal conductivity of the said compositions are shown in Tables 1 and 2.

[0049]

[0050]

[0051] Regarding the evaluation results, the compositions of Examples 1 to 16, which satisfy the requirements of the present invention, were pastes with good operability and did not separate even when shear force was applied. In contrast, the compositions of Comparative Examples 1 to 4, which do not contain metal powder with a melting point of 900°C or higher, were paste-like before shear force was applied, but when shear force was applied, the filler separated, resulting in poor operability.

[0052] Furthermore, the compositions of Comparative Examples 1 to 4 exhibited inferior thermal conductivity compared to the Examples containing the same thermally conductive ceramic filler. This is thought to be because the low fluidity of the paste caused the filler to separate when preparing the thermal conductivity measurement sample, and the separated areas became the thermal resistance.

Claims

1. A composition comprising (A) Ga or a Ga alloy, (B) a thermally conductive ceramic filler, and (C) a metal powder having a melting point of 900°C or higher.

2. The composition according to claim 1, wherein the (C) metal powder having a melting point of 900°C or higher includes transition metals belonging to the fourth and fifth periods.

3. The composition according to claim 1, characterized in that the filling rate of the (B) thermally conductive ceramic filler is 25 to 70 volume percent.

4. The composition according to claim 1, characterized in that the filling rate of the metal powder having a melting point of 900°C or higher is 1 to 20% by volume.

5. An electronic component comprising the composition described in any one of claims 1 to 4.

6. A semiconductor device comprising the composition according to any one of claims 1 to 4.

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