WO2019188614A1

WO2019188614A1 - Semiconductor package

Info

Publication number: WO2019188614A1
Application number: PCT/JP2019/011568
Authority: WO
Inventors: 真琴沓水; 健介村島; 聡志奥; 克洋竹馬
Original assignee: 株式会社カネカ
Priority date: 2018-03-28
Filing date: 2019-03-19
Publication date: 2019-10-03
Also published as: JP2021100006A

Abstract

A semiconductor package (30) comprises: an anisotropic graphite composite (10); and a semiconductor element (8). The anisotropic graphite composite (10) includes anisotropic graphite (1), a metal layer (7), and an inorganic material layer (6). The crystal orientation plane of the graphite layer forming the anisotropic graphite (1) is parallel to the X-Z plane; the semiconductor element (8) is joined to the inorganic material layer (6) such that the long sides of the semiconductor element (8) are perpendicular to the X-Z plane; and a ratio (La/l2) of the average value (La) of the length of the four sides of the anisotropic graphite composite (10) parallel to the X-axis and the length (l2) of the short sides of the semiconductor element (8) is 3 or higher. Due to this configuration, a semiconductor package having high heat dissipation is provided.

Description

Semiconductor package

The present invention relates to a semiconductor package with high heat dissipation.

Anisotropic graphite is formed by laminating many graphites, and graphite has a crystal orientation plane. Anisotropic graphite has the property that the thermal conductivity in the direction parallel to the crystal orientation plane of graphite is high, but the thermal conductivity in the perpendicular direction is low.

In a semiconductor package, anisotropic graphite is used as a material that dissipates heat by efficiently transferring heat from a semiconductor element to a cooler so that heat generated from a semiconductor element disposed on the anisotropic graphite is not concentrated.

Patent Document 1 discloses an anisotropic heat conduction element that transfers heat from a heat source. The anisotropic heat transfer element includes a structure in which graphene sheets are stacked along a plane intersecting a contact surface with a heat source. That is, when the X axis, the Y axis orthogonal to the X axis, and the Z axis perpendicular to the XY plane are defined, it is defined that the graphene sheet is parallel to the Z axis.

Japanese Patent Publication “Japanese Unexamined Patent Publication No. 2011-23670”

However, Patent Document 1 does not describe the direction of the structure relative to the heat source or the ratio between the heat source and the length of the structure. Such an anisotropic heat transfer element cannot be said to have good efficiency in radiating heat from a heat source.

An object of the present invention is to provide a semiconductor package that is efficient in dissipating heat from a heat source, that is, has high heat dissipation.

In the semiconductor package including the anisotropic graphite composite including the anisotropic graphite, the metal layer, and the inorganic material layer, and the semiconductor element, the inventors of the present invention have the orientation of the anisotropic graphite composite relative to the semiconductor element. It was found that a semiconductor package with high heat dissipation can be obtained by setting the ratio between the length of the semiconductor element and the anisotropic graphite within a specific range. In addition, the present inventors have combined graphite and an inorganic material layer having an isotropic thermal diffusivity in order to compensate for the thermal diffusivity in the direction perpendicular to the crystal orientation plane in anisotropic graphite. It has been found that it is effective to use isotropic graphite, and the present invention has been completed.

That is, one embodiment of the present invention includes the invention shown in [1] below.
[1] A semiconductor package according to an aspect of the present invention is a semiconductor package including (A) an anisotropic graphite composite and (B) a semiconductor element,
(A) comprises (a1) anisotropic graphite, (a2) metal layer, and (a3) inorganic material layer,
(A1) and (a3) are joined by (a2),
X-axis, Y-axis orthogonal to X-axis, Z-axis perpendicular to the plane including X-axis and Y-axis,
The average value of the lengths of the four sides (side a) parallel to the X axis in (A) is La,
The average value of the lengths of the four sides (side b) parallel to the Y axis in (A) is Lb,
When the average value of the lengths of the four sides (side c) parallel to the Z axis in (A) is Lc,
The crystal orientation plane of the graphite layer forming the (a1) is parallel to the XZ plane including the X axis and the Z axis;
The length of the long side of (B) is l1,
The length of the short side of (B) is l2,
When the thickness of the (B) is l3,
(B) is joined to (a3) included in (A) so that the long side of (B) is perpendicular to the XZ plane including the X axis and the Z axis,
The ratio (La / l2) of the average value (La) of the lengths of the four sides parallel to the X axis in (A) and the length (l2) of the short sides in (B) is 3 or more.

According to the present invention, a semiconductor package with high heat dissipation can be provided.

It is a perspective view which shows the structure of the (A) anisotropic graphite complex which concerns on 1 aspect of this invention. 1 is a perspective view illustrating a configuration of a semiconductor package according to one embodiment of the present invention. It is a disassembled perspective view which shows the manufacturing method of the (A) anisotropic graphite complex which concerns on 1 aspect of this invention. It is a disassembled perspective view which shows the manufacturing method of the (A) anisotropic graphite complex which concerns on 1 aspect of this invention. It is a perspective view which shows the structure of the semiconductor package which concerns on Example 1 of this invention. It is a top view of the semiconductor package which concerns on Example 1 of this invention. 7 is a top view of a semiconductor package according to Examples 2 to 9 of the present invention. FIG. 7 is a top view of a semiconductor package according to Comparative Example 1. FIG. 10 is a top view of a semiconductor package according to Comparative Example 2. FIG.

One embodiment of the present invention will be described below, but the present invention is not limited to this. The present invention is not limited to each configuration described below, and various modifications are possible within the scope shown in the claims, and technical means disclosed in different embodiments and examples are appropriately used. Embodiments and examples obtained in combination are also included in the technical scope of the present invention. Moreover, all the academic literatures and patent literatures described in this specification are used as references in this specification. Unless otherwise specified in this specification, “A to B” representing a numerical range means “A or more and B or less”. In this specification, “parallel” means a concept including “parallel” and a category considered to be “substantially parallel” in the technical field of the present invention. , "Vertical" and a category that is considered "substantially vertical" in the technical field of the present invention.

A semiconductor package according to one embodiment of the present invention is a semiconductor package including (A) an anisotropic graphite composite and (B) a semiconductor element,
The (A) anisotropic graphite composite comprises (a1) anisotropic graphite, (a2) a metal layer, and (a3) an inorganic material layer,
(A1) anisotropic graphite and (a3) inorganic material layer are joined by (a2) metal layer;
X-axis, Y-axis orthogonal to X-axis, Z-axis perpendicular to the plane including X-axis and Y-axis,
The average value of the lengths of the four sides (side a) parallel to the X axis of the (A) anisotropic graphite composite is La,
The average value of the lengths of the four sides (side b) parallel to the Y axis of the (A) anisotropic graphite composite is Lb,
When the average value of the lengths of the four sides (side c) parallel to the Z axis of the (A) anisotropic graphite composite is Lc,
(A1) the crystal orientation plane of the graphite layer forming the anisotropic graphite is parallel to the XZ plane including the X axis and the Z axis;
(B) The length of the long side of the semiconductor element is l1,
(B) The length of the short side of the semiconductor element is l2,
When the thickness of the (B) semiconductor element is l3,
(B) The anisotropic graphite composite is provided in the (B) semiconductor element so that the long side of the (B) semiconductor element is perpendicular to the XZ plane including the X axis and the Z axis ( a3) Bonded to the inorganic material layer,
The ratio (La / l2) of the average value (La) of the lengths of the four sides parallel to the X axis of the (A) anisotropic graphite composite and the length (l2) of the short sides of the (B) semiconductor element ) Is 3 or more.

(A) An anisotropic graphite composite, (B) a semiconductor element, and the like, which are members constituting a semiconductor package according to one embodiment of the present invention, will be described below.

<(A) Anisotropic graphite composite>
In the following description, the X axis, the Y axis orthogonal to the X axis, and the Z axis perpendicular to the plane including the X axis and the Y axis are defined, and as shown in FIG. Of the sides of the body 10, four sides parallel to the X axis are side a (reference numeral “3” in FIG. 1 and the like), four sides parallel to the Y axis are side b (reference numeral “4” in FIG. 1 and the like), Z Four sides parallel to the axis are defined as side c (symbol “5” in FIG. 1 and the like).

As shown in FIG. 1, (A) anisotropic graphite composite 10 according to one embodiment of the present invention includes (a1) anisotropic graphite 1, (a2) metal layer 7, and (a3) inorganic material layer 6. Consists of. (A) The anisotropic graphite 1 constituting the anisotropic graphite composite 10 has a crystal orientation plane 2, and graphite is laminated in parallel with the crystal orientation plane 2.

Note that reference numeral “2” in FIG. 1 and the like indicates the crystal orientation plane of the anisotropic graphite represented by “thin lines” in FIG. 1, and (a1) indicates the upper surface of the anisotropic graphite. is not.

<Semiconductor package>
As shown in FIG. 2, the semiconductor package 30 according to one embodiment of the present invention includes (B) a semiconductor element 8, (A) an anisotropic graphite complex 10, and a cooler 9 in order from the semiconductor element side. The

<Configuration of (a1) Anisotropic Graphite and (B) Semiconductor Device>
In the semiconductor package according to one embodiment of the present invention, (A) the direction of the crystal orientation plane of the anisotropic graphite (A1) in the anisotropic graphite complex, and (A) (B ) The orientation of the semiconductor element is important.

First, the direction of the crystal orientation plane of (a1) anisotropic graphite in (A) anisotropic graphite composite will be described. As shown in FIG. 2, in order to efficiently transfer heat from the (B) semiconductor element 8 to the cooler 9 through the (A) anisotropic graphite complex, (a1) the crystal orientation plane of the anisotropic graphite 1 2 (FIG. 1) is placed parallel to the XZ plane. Thus, (B) heat can be efficiently transferred from the semiconductor element 8 in the X-axis direction and the Z-axis direction.

Subsequently, (A) the direction of the (B) semiconductor element relative to the anisotropic graphite composite will be described. As shown in FIG. 2, (A) the semiconductor element 8 is arranged so that the long side 81 thereof is perpendicular to the side a of the anisotropic graphite composite 10 (symbol “3” in FIG. 2). Deploy. In addition, (B) the average value (La) of the lengths of the four sides of the side a of the anisotropic graphite composite 10 with respect to the length l2 of the short side 82 of the semiconductor element 8 is three times or more. To do. Accordingly, (B) heat can be efficiently transferred from the semiconductor element 8 to the cooler 9.

<(B) Shape of semiconductor element>
(B) The shape of the semiconductor element viewed from the Z-axis direction may be a rectangle or other than a rectangle. For example, a rhombus, a shape having four sides with rounded corners, or an ellipse may be used. In the case of a shape other than a rectangle, (B) the length (l1) of the long side and the length (l2) of the short side of the semiconductor element are defined by the maximum length of the semiconductor element and the minimum length of the semiconductor element.

<(A) Definition of length of each side of anisotropic graphite composite and (B) length and thickness of each side of semiconductor element>
(A) In the anisotropic graphite composite, the average value of the lengths of the four sides (side a) parallel to the X axis is La, and the average value of the lengths of the four sides (side b) parallel to the Y axis is Let Lb be the average value of the lengths of the four sides (side c) parallel to the Z axis.

(B) In the semiconductor element, the length of the long side is l1, the length of the short side is l2, and the thickness is l3.

(La / l2)
(A) The average value (La) of the lengths of the four sides a of the anisotropic graphite composite is 3 times or more and 5 times the length l2 of the short side of the semiconductor element (B). The above is more preferable.

(La)
(A) The average value (La) of the lengths of the four sides a of the anisotropic graphite composite is preferably 4 mm or more and 200 mm or less because heat can be efficiently diffused. The range of 100 mm or less is more preferable.

(Lb)
(A) The average value (Lb) of the lengths of the four sides b of the anisotropic graphite composite is preferably not less than (B) the length 11 of the long side of the semiconductor element. Since it can diffuse, the range of 6 mm or more and 100 mm or less is preferable, and the range of 10 mm or more and 50 mm or less is more preferable.

(Lc)
(A) The average value (Lc) of the lengths of the four sides c of the anisotropic graphite composite is shorter in order to reduce the thermal resistance in the Z-axis direction from the semiconductor element to the cooler (B). Although (B) it is preferable that the heat is diffused in the direction of the XZ plane before the heat reaches the cooler from the semiconductor element. Therefore, since the average value (Lc) can express the heat transfer performance more effectively, the range is preferably 0.6 mm or more and 5.0 mm or less, and 1.0 mm or more and 3.5 mm or less. The range is more preferable, the range of 1.0 mm or more and 3.0 mm or less is further preferable, and the range of 1.2 mm or more and 2.5 mm or less is particularly preferable.

<(A1) Method for producing anisotropic graphite>
The (a1) anisotropic graphite according to one embodiment of the present invention can be produced by cutting a graphite block having a graphene structure in which six-membered rings are connected by a covalent bond into a predetermined plate shape.

<Graphite block>
The graphite block is not particularly limited as long as it has a graphene structure in which six-membered rings are connected by a covalent bond. A graphene structure in which six-membered rings are connected by a covalent bond has high thermal conductivity in the crystal orientation plane. As the graphite block, for example, a polymer-decomposed graphite block, a pyrolytic graphite block, an extruded graphite block, a molded graphite block, or the like can be used. Among them, the crystal orientation plane of a graphene structure in which six-membered rings are connected by a covalent bond has a high thermal conductivity of 1500 W / mK or more, and (A) the anisotropic graphite composite has excellent heat transfer performance. It is preferable to use a molecularly decomposed graphite block or a pyrolytic graphite block.

<Method for producing graphite block>
A first method for producing a graphite block suitably used for a semiconductor package according to one embodiment of the present invention is to introduce a carbonaceous gas such as methane into a furnace and heat it to about 2000 ° C. with a heater to form fine carbon nuclei. It is a method of forming. The formed carbon nuclei are deposited in layers on the substrate. Thereby, a pyrolytic graphite block can be obtained.

The second manufacturing method of the graphite block suitably used for the semiconductor package according to one embodiment of the present invention is a method of manufacturing by laminating a polymer film such as a polyimide resin in multiple layers and then performing heat treatment while pressing and pressing. is there. Specifically, to obtain a graphite block from a polymer film, first, a polymer film as a starting material is laminated in multiple layers, and preheated at a temperature of about 1000 ° C. under reduced pressure or in an inert gas atmosphere. And carbonized to form a carbonized block. Thereafter, the carbonized block is graphitized by heat treatment at a temperature of 2800 ° C. or higher while being press-pressed in an inert gas atmosphere. Thereby, a good graphite crystal structure can be formed, and a graphite block excellent in thermal conductivity can be obtained.

As a method for cutting the graphite block, a known method using a diamond cutter, a wire saw, machining, or the like can be appropriately selected, but a method using a wire saw can be easily processed into a substantially rectangular parallelepiped shape. More preferred.

The surface of the graphite block may be polished or roughened, and known techniques such as file polishing, buffing, and blasting can be used as appropriate.

<Configuration of (A) Anisotropic Graphite Composite>
(A) In the anisotropic graphite composite, (a1) At least one of the upper and lower surfaces (surface parallel to the XY plane) of anisotropic graphite has (a2) a metal layer and (a3) inorganic A material layer is formed, and (a1) anisotropic graphite and (a3) inorganic material layer are joined by (a2) metal layer. It is more preferable that (a2) the metal layer and (a3) the inorganic material layer are formed on the upper and lower surfaces of (a1) anisotropic graphite, because of excellent thermal conductivity, (a1) anisotropic graphite More preferably, it is formed on at least one of the upper and lower surfaces and the side surface, and (a1) it is particularly preferably formed on all six surfaces of the anisotropic graphite.

<(A3) Inorganic material layer>
(A3) Examples of the inorganic material layer include a metal layer or a ceramic layer made of an isotropic material. (A1) Heat is relatively difficult to transfer in the direction perpendicular to the crystal orientation plane in the anisotropic graphite (Y-axis direction). Therefore, by combining with an isotropic material having a relatively high thermal conductivity, (a1) the thermal conductivity in the Y-axis direction of anisotropic graphite can be supplemented, and a higher heat dissipation effect is exhibited. be able to.

Examples of the metal forming the metal layer include known materials such as gold, silver, copper, nickel, aluminum, molybdenum, tungsten, and alloys containing these metals.

Examples of the ceramic forming the ceramic layer include known materials such as alumina, zirconia, silicon carbide, silicon nitride, boron nitride, and aluminum nitride.

(A3) As the inorganic material layer, a metal layer is more preferable, and as a metal forming the metal layer, copper is more preferable because thermal conductivity can be further improved.

<(A3) Thickness of inorganic material layer>
(A3) The thickness of the inorganic material layer is preferably in the range of 100 μm to 300 μm, and more preferably in the range of 120 μm to 250 μm. (A3) If the thickness of the inorganic material layer is 100 μm or more, (a1) thermal conductivity in a direction in which the heat of anisotropic graphite is relatively difficult to be transmitted can be compensated. Moreover, if the thickness of the (a3) inorganic material layer is 300 μm or less, (a1) the high thermal conductivity of the anisotropic graphite is not hindered.

<(A3) Formation method of inorganic material layer>
Examples of the method for forming the (a3) inorganic material layer include (a2) a method of performing plating or sputtering on the metal layer, or (a2) a method of attaching a plate to be the (a3) inorganic material layer to the metal layer. Since it is excellent in thermal conductivity, a method of attaching a plate to be (a3) an inorganic material layer to the (a2) metal layer is more preferable.

The (a1) anisotropic graphite is more preferably covered by (a3) an inorganic material layer, and more preferably the whole surface is covered.

<(A2) Metal layer>
The (a2) metal layer is used to join (a1) anisotropic graphite and (a3) an inorganic material layer.

<(A2) Metal layer thickness>
(A2) Although the thickness of the metal layer is not particularly limited, it is in the range of 8 μm or more and 50 μm because it has good interfacial adhesion as a bonding material and can suppress an increase in thermal resistance. It is preferable.

<(A2) Material of metal layer>
(A2) The metal layer is not particularly limited, but a metal layer formed by plating and a metal layer formed by a metal brazing material or solder are more preferable.

When (a2) metal layer is formed by plating, the (a2) metal layer and (a3) inorganic material layer may be integrated.

The (a2) metal layer formed of the metal brazing material can diffuse and bond to (a1) anisotropic graphite, and since its own thermal conductivity is relatively high, it has high thermal conductivity. Can be maintained.

For example, if (a2) the metal layer is a metallic brazing material and (a3) the inorganic material layer is a copper layer, as shown in FIG. 2, (a2) metal layer 7 and (a3) inorganic material layer 6 and ( a1) The anisotropic graphite 1 can be joined.

Although the type of the metallic brazing material is not particularly limited, (a3) it is more preferable to contain silver, copper, and titanium because it has excellent thermal conductivity like the inorganic material layer.

<(A2) When the metal layer is a metal brazing material>
Examples of the joining method using the metal brazing material include a known material and a method using a known technique. For example, when activated silver brazing is used as the metallic brazing material, it is heated for 10 minutes to 1 hour in a vacuum environment of 1 × 10 ⁻³ Pa and a temperature range of 700 to 1000 ° C., and then cooled to room temperature. Thus, (a1) anisotropic graphite and (a3) inorganic material layer can be joined. Moreover, in order to make a joining state favorable, you may apply a load to (a1) anisotropic graphite or (a3) inorganic material layer at the time of a heating.

When (a3) the inorganic material layer is bonded to the entire surface of (a1) anisotropic graphite using (a2) a metal brazing material as the metal layer, as shown in FIG. (A) An anisotropic graphite composite is formed by a method using a hollow frame 21 as an inorganic material layer, or a method using a bottomed frame 22 as an inorganic material layer as shown in FIG. It is preferable. (A1) Compared with the case where (a3) the inorganic material layer is bonded to each surface of the anisotropic graphite 1, (a3) the interface between the inorganic material layers is reduced. Heat can be diffused efficiently.

(Method using hollow frame)
A method using the hollow frame 21 as the (a3) inorganic material layer will be described with reference to FIG. In the system using the hollow frame 21, (a3) a lid 20 as an inorganic material layer, (a2) a metal brazing material or solder that becomes the metal layer 7 as a bonding material, (a1) anisotropic (A) An anisotropic graphite composite 10 can be manufactured by disposing the heat-resistant graphite 1, (a2) the metal brazing material or solder to be the metal layer 7 and the lid 20 in this order and heat-bonding them. . At this time, if the metal brazing material or the solder is bonded to the metal plate 20 in advance, (a1) the anisotropic graphite 1 and the metal plate 20 can be bonded more efficiently.

(Method using a bottomed frame)
A method using the bottomed frame 22 as the (a3) inorganic material layer will be described with reference to FIG. The manufacturing method of the bottomed frame 22 is not particularly limited, but a known method such as a method of cutting out from a plate, a method of bending a cross-shaped plate (FIG. 4) into a box shape, a method of drawing, or the like is appropriately used. You can choose. In the method using the bottomed frame 22 produced in this way, (a2) a metal brazing material or solder to be the metal layer 7 as a bonding material, (a1) anisotropy, inside the bottomed frame 22. Graphite 1, (a2) metallic brazing material or solder to be the metal layer 7, and (a3) the lid 20 is disposed in this order as an inorganic material layer, and heat-bonded to form (A) the anisotropic graphite composite 10 Can be produced. At this time, if the metallic brazing material or solder is bonded in advance to the bottomed frame 22 and the metal plate 20, the (a1) anisotropic graphite 1, the bottomed frame 22 and the metal plate 20 are more efficiently bonded. Can be joined.

<(A2) Impregnation of (a1) anisotropic graphite of metal layer>
In (A) the anisotropic graphite composite according to one aspect of the present invention, (a2) a part of the metal layer is impregnated into, for example, at least part of the interlayer of the graphite layer forming the anisotropic graphite (a1) Thus, it is preferable to exist. That is, it is preferable that (A) the anisotropic graphite complex includes (a2) a part of the metal layer in at least a part of the layer of the graphite layer forming the anisotropic graphite. (A1) There may be a minute gap between the layers of the anisotropic graphite, and this gap hinders the heat transfer performance of the (A) anisotropic graphite composite. Therefore, the presence of a part of the metal layer (a2) in the gap can exhibit good heat transfer properties.

(A2) A method of impregnating or existing a metal layer between (a1) graphite layers forming anisotropic graphite is as follows: (a3) When inorganic material layer and (a2) metal layer are heat-bonded An effective method is to deliberately expand the graphite layer where minute gaps exist.

As a method for efficiently expanding the interlayer of the graphite layer at the time of heat bonding, (a1) As anisotropic graphite, a polymer film such as polyimide resin is laminated in multiple layers, and then heat-treated while pressing with pressure. That is, a method of producing polymer-decomposed graphite by thermal decomposition is preferable. Since polymer-decomposed graphite is produced by laminating polymer films in multiple layers, a gap is formed linearly between the layers derived from the polymer film, compared to pyrolytic graphite produced by the CVD method, etc. can do. Therefore, the metal brazing material or solder can be easily impregnated.

Next, the semiconductor package according to the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to only the examples.

<Evaluation of heat transfer performance>
As shown in FIG. 5, (B) a semiconductor element 8 (11: 6 mm, 12: 2 mm) was joined to the central portion of the upper surface of (A) the anisotropic graphite composite 10 with solder. Further, (A) a water-cooled cooler 9 (dimensions: 30 mm × 30 mm) is placed on the lower surface of the anisotropic graphite composite 10, and a silicone oil compound (product name: G-775) manufactured by Shin-Etsu Chemical Co., Ltd. Used to attach. Water of 25 ° C. was circulated through the cooler 9. Then, (B) the temperature of the semiconductor element 8 was measured with a thermocouple in a state where a heat amount of 40 W was applied to the semiconductor element 8.

As a result of the measurement, (B) if the temperature of the semiconductor element 8 is 160 ° C. or lower, the rank is “A”, and if it exceeds 160 ° C. and is 164 ° C. or lower, the rank is “B”. If the rank exceeds “C” and 179 ° C., the rank is “D”. If the rank is A, B, or C, the semiconductor package has excellent heat transfer performance (if it is 179 ° C. or less). This is a semiconductor package with excellent heat transfer performance. The temperature was rounded off to the first decimal place.

<Production Example 1>
A graphite block was produced by the following method.

After laminating 1500 sheets of Kaneka's polyimide film (dimensions: 100 mm × 100 mm, thickness 25 μm), press and pressurize with a pressure of 40 kg / cm ² , under an inert gas atmosphere, at a maximum temperature of 2900 ° C. A graphite block (dimensions: 90 mm × 90 mm, thickness 15 mm) was produced by heat treatment.

The thermal conductivity of the produced graphite block was 1500 W / mK in the direction of the crystal orientation plane and 5 W / mK in the vertical direction of the crystal orientation plane.

<Example 1>
The graphite block (dimensions: 90 mm × 90 mm, thickness 15 mm) produced in Production Example 1 was placed so that the crystal orientation plane of graphite was parallel to the XZ plane, and cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 6 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)). (A1) anisotropic graphite having a length of 10 mm and a side (side c) parallel to the Z axis (and its average value (Lc)) of 0.6 mm was obtained.

Next, as shown in FIG. 5, the length of the side a is 6 mm, the length of the side b is 10 mm, and the length of the side c is 0.6 mm. (A1) (A2) Titanium-based active silver solder having a thickness (ta, tb) of 20 μm as the metal layer 7 and (a3) oxygen-free copper having a thickness (Ta, Tb) of 200 μm as the inorganic material layer 6 were stacked in this order. Then, by applying a load of 100 kg / m ² from the top and bottom in the Z-axis direction and heating at 850 ° C. for 30 minutes in a vacuum environment of 1 × 10 ⁻³ Pa, (a1) the anisotropic graphite 1 (A) An anisotropic graphite composite 10 provided with (a2) the metal layer 7 on the upper and lower surfaces (surface parallel to the XY plane) was obtained.

In the obtained (A) anisotropic graphite composite 10, (a1) a part of the titanium-based active silver brazing which is the metal layer 7 is located in a part of the interlayer of the graphite layer of the anisotropic graphite 1. Existed.

Next, as shown in FIGS. 5 and 6, (A) the anisotropic graphite composite 10 is disposed on the cooler 9, and (B) the semiconductor element is formed on (A) the anisotropic graphite composite 10. 8 was arranged to produce a semiconductor package 30. As shown in FIG. 6, (B) the semiconductor element 8 is such that (A) the long side 81 is perpendicular to the side a of the anisotropic graphite composite 10 (reference numeral “3” in FIG. 2, etc.). Arranged. The ratio (La / l2) between the average value (La) of the four sides of the side a and the length (l2) of the short side 82 of the (B) semiconductor element 8 was 3.

The temperature of the (B) semiconductor element 8 was measured at 173 ° C. with 40 W of heat applied to the (B) semiconductor element 8 in the manufactured semiconductor package 30. Therefore, the evaluation of the heat transfer performance was rank “C”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 2>
The graphite block produced in Production Example 1 was arranged so that the crystal orientation plane of graphite was parallel to the XZ plane, and was cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 10 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)). 10 mm, the length of the side (side c) parallel to the Z-axis (and its average value (Lc)) is 0.6 mm (a1) The same as in Example 1 except that anisotropic graphite was obtained. The semiconductor package 30 was manufactured by performing the operation as shown in FIG. (A) Ratio (La / l2) of the average value (La) of the lengths of the four sides a of the anisotropic graphite composite 10 to the length (l2) of the short side 82 of the (B) semiconductor element 8 ) Was 5.

The temperature of the (B) semiconductor element 8 was measured in a state where a heat amount of 40 W was applied to the (B) semiconductor element 8 in the manufactured semiconductor package 30 and found to be 163 ° C. Therefore, the evaluation of the heat transfer performance was rank “B”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 3>
(A3) Except that aluminum nitride having a thickness (Ta, Tb) of 200 μm was used as the inorganic material layer 6, the same operation as in Example 2 was performed to produce a semiconductor package 30 as shown in FIG.

When the temperature of (B) semiconductor element 8 was measured in a state where a heat amount of 40 W was applied to (B) semiconductor element 8 in the produced semiconductor package 30, it was 178 ° C. Therefore, the evaluation of the heat transfer performance was rank “C”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 4>
(A3) Except that oxygen-free copper having a thickness (Ta, Tb) of 80 μm was used as the inorganic material layer 6, the same operation as in Example 2 was performed to produce a semiconductor package 30 as shown in FIG. .

When the temperature of (B) semiconductor element 8 was measured in the state where 40 W of heat was applied to (B) semiconductor element 8 in the produced semiconductor package 30, it was 170 ° C. Therefore, the evaluation of the heat transfer performance was rank “C”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 5>
(A3) Except for using oxygen-free copper having a thickness (Ta, Tb) of 320 μm as the inorganic material layer 6, the same operation as in Example 2 was performed to produce a semiconductor package 30 as shown in FIG. .

The temperature of the (B) semiconductor element 8 was measured at 165 ° C. in a state where a heat amount of 40 W was applied to the (B) semiconductor element 8 in the manufactured semiconductor package 30. Therefore, the evaluation of the heat transfer performance was rank “C”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 6>
The graphite block produced in Production Example 1 was arranged so that the crystal orientation plane of graphite was parallel to the XZ plane, and was cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 10 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)). (A1) anisotropic graphite having a length of 10 mm and a side (side c) parallel to the Z axis (and its average value (Lc)) of 0.6 mm was obtained. Titanium-based active silver brazing having a thickness (ta, tb) of 20 μm was overlaid on the upper and lower surfaces of (a1) anisotropic graphite 1 as (a2) metal layer 7. Thereafter, by performing electrolytic copper plating, a copper layer having a thickness (Ta, Tb) of 200 μm was formed as (a3) inorganic material layer 6 on (a2) metal layer 7. Note that (a1) a mask was applied to the side surface of the anisotropic graphite 1 before electrolytic copper plating, and the mask was removed after electrolytic copper plating. As a result, (a1) electrolytic copper plating was not formed on the side surface of the anisotropic graphite 1. Thereafter, the same operation as in Example 2 was performed to produce a semiconductor package 30 as shown in FIG.

The temperature of the (B) semiconductor element 8 was measured at 167 ° C. with a heat amount of 40 W applied to the (B) semiconductor element 8 in the manufactured semiconductor package 30. Therefore, the evaluation of the heat transfer performance was rank “C”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 7>
The graphite block produced in Production Example 1 was arranged so that the crystal orientation plane of graphite was parallel to the XZ plane, and was cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 9.6 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)) )) Was 9.6 mm, and the length of the side (side c) parallel to the Z-axis (and its average value (Lc)) was 0.6 mm. (A1) An anisotropic graphite was obtained.

Further, (a3) oxygen-free copper as the inorganic material layer 6, as shown in FIG. 3, the outer dimension of the frame is 10 mm × 10 mm, the inner dimension of the frame is 9.6 mm × 9.6 mm, the width of the frame Is formed into a hollow frame 21 (no cavity inside the frame) having a thickness of 0.2 mm and a thickness of 1.0 mm (0.6 + 0.2 + 0.2 mm), and the dimensions are 9.6 mm × 9.6 mm, thickness Was formed into two lids 20 having a thickness of 200 μm (0.2 mm).

Then, inside the hollow frame 21, a lid 20, a bonding material (a2) a titanium-based active silver solder having a thickness (ta, tb) of 20 μm as the metal layer 7, (a1) anisotropic graphite 1, (a2) A titanium-based active silver solder having a thickness (ta, tb) of 20 μm and a lid 20 were arranged in this order as the metal layer 7. Then, by applying a load of 100 kg / m ² from above and below in the Z-axis direction, heating at 850 ° C. for 30 minutes in a vacuum environment of 1 × 10 ⁻³ Pa, (A) anisotropic graphite composite 10 was obtained.

In the obtained (A) anisotropic graphite composite 10, (a1) the titanium-based active silver brazing which is the metal layer 7 exists on the entire surface of the anisotropic graphite 1, and (a1) the anisotropy A part of (a2) the titanium-based active silver brazing which is the metal layer 7 was present in a part of the graphite layer of the graphite 1. Thereafter, the same operation as in Example 2 was performed to produce a semiconductor package 30 as shown in FIG.

When the temperature of (B) semiconductor element 8 was measured in the state where 40 W of heat was applied to (B) semiconductor element 8 in the produced semiconductor package 30, it was 162 ° C. Therefore, the evaluation of the heat transfer performance was rank “B”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 8>
The graphite block produced in Production Example 1 was arranged so that the crystal orientation plane of graphite was parallel to the XZ plane, and was cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 9.6 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)) )) Was 9.6 mm, and the length of the side (side c) parallel to the Z-axis (and its average value (Lc)) was 0.6 mm. (A1) An anisotropic graphite was obtained.

Further, (a3) an oxygen-free copper plate having a thickness of 200 μm as the inorganic material layer 6, as shown in FIG. The dimensions are 10mm x 10mm, the height is 1.0mm (0.6 + 0.2 + 0.2mm), the inner dimensions of the frame are 9.6mm x 9.6mm, and the depth is 0.8mm (0.6 + 0.2mm) And a lid 20 having a size of 9.6 mm × 9.6 mm and a thickness of 200 μm (0.2 mm).

And inside the bottomed frame 22, (a2) titanium-based active silver brazing having a thickness (ta, tb) of 20 μm as a metal layer 7 as a bonding material, (a1) anisotropic graphite 1, (a2) metal layer 7, a titanium-based active silver solder having a thickness (ta, tb) of 20 μm and a lid 20 were arranged in this order. Then, by applying a load of 100 kg / m ² from above and below in the Z-axis direction, heating at 850 ° C. for 30 minutes in a vacuum environment of 1 × 10 ⁻³ Pa, (A) anisotropic graphite composite 10 was obtained.

The temperature of (B) semiconductor element 8 was measured in a state where a heat amount of 40 W was applied to (B) semiconductor element 8 in the produced semiconductor package 30 and found to be 160 ° C. Therefore, the evaluation of the heat transfer performance was rank “A”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Example 9>
(A1) The same operation as in Example 2 was performed except that a highly heat conductive carbon material (trade name: PYROID HT) manufactured by MINTEQ International Inc. was used as the anisotropic graphite 1, as shown in FIG. In addition, a semiconductor package 30 was produced.

In the obtained (A) anisotropic graphite composite 10, (a2) the metal layer 7 did not exist between the graphite layers of (a1) anisotropic graphite 1.

<Comparative Example 1>
As shown in FIG. 8, (B) the semiconductor element 8 is arranged so that the long side 81 thereof is parallel to the side a (reference numeral “3” in FIG. 8) of the (A) anisotropic graphite composite 10. A semiconductor package 30 was fabricated by performing the same operation as in Example 2 except that the semiconductor package 30 was disposed.

When the temperature of (B) semiconductor element 8 was measured in the state where 40 W of heat was applied to (B) semiconductor element 8 in the produced semiconductor package 30, it was 187 ° C. Therefore, the evaluation of the heat transfer performance was rank “D”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Comparative example 2>
The graphite block produced in Production Example 1 was arranged so that the crystal orientation plane of graphite was parallel to the XZ plane, and was cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 4 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)). (A1) anisotropic graphite having a length of 10 mm and a side (side c) parallel to the Z axis (and its average value (Lc)) of 0.6 mm was obtained. Except that this (a1) anisotropic graphite was used, the same operation as in Example 2 was performed to produce a semiconductor package 30 as shown in FIG. (A) The average value (La) of the lengths of the four sides of the side a (symbol “3” in FIG. 9) of the anisotropic graphite composite 10 and the length of the short side 82 of the (B) semiconductor element 8. The ratio (La / l2) to (l2) was 2.

The temperature of the (B) semiconductor element 8 was measured at 185 ° C. with 40 W of heat applied to the (B) semiconductor element 8 in the fabricated semiconductor package 30. Therefore, the evaluation of the heat transfer performance was rank “D”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

<Comparative Example 3>
The graphite block produced in Production Example 1 was arranged so that the crystal orientation plane of graphite was parallel to the XZ plane, and was cut with a wire saw. Thus, the length of the side (side a) parallel to the X axis (and its average value (La)) is 10 mm, and the length of the side (side b) parallel to the Y axis (and its average value (Lb)). (A1) anisotropic graphite having a length of 10 mm and a side (side c) parallel to the Z axis (and its average value (Lc)) of 1.0 mm was obtained. Using this (a1) anisotropic graphite alone, that is, without using (a2) the metal layer and (a3) the inorganic material layer, the same operation as in Example 2 was performed to produce a semiconductor package.

The temperature of the (B) semiconductor element was measured at a temperature of 194 ° C. with 40 W of heat applied to the (B) semiconductor element in the manufactured semiconductor package. Therefore, the evaluation of the heat transfer performance was rank “D”. The evaluation results are shown in Table 1 together with the configuration of the semiconductor package.

From the comparison between Example 2 and Comparative Example 1, the heat transfer performance of the semiconductor package is improved by arranging (B) the long side of the semiconductor element perpendicularly to (a1) the side a of the anisotropic graphite. I understand that. This is because in (a1) anisotropic graphite, the heat transfer area can be increased in the direction of side a, which has 300 times higher thermal conductivity than side b.

Further, from the comparison between Example 1 and Comparative Example 2, (a1) the side a of the anisotropic graphite is set to a length of three times or more with respect to the short side of the (B) semiconductor element. It can be seen that the heat transfer performance is improved.

From comparison between Example 2 and Example 3 and Comparative Example 3, (a1) Arranging (a3) inorganic material layers on the upper and lower surfaces of anisotropic graphite may improve the heat transfer performance of the semiconductor package. I understand. This is because (a1) anisotropic graphite was able to improve the heat transfer performance in the direction of side b, which has a relatively low thermal conductivity. Further, from comparison between Example 2 and Example 3, it can be seen that (a3) oxygen-free copper is preferable to aluminum nitride as the inorganic material layer.

From comparison between Example 2, Example 4 and Example 5, the length of side a is 10 mm, the length of side b is 10 mm, and the length of side c is 0.6 mm. On the other hand, the thickness of the oxygen-free copper is preferably 200 μm, and it can be seen that the heat transfer performance of the semiconductor package is slightly deteriorated whether it is thicker (320 μm) or thinner (80 μm). This is to achieve both (a1) improvement of heat transfer performance to the side b having relatively low thermal conductivity and maintenance of heat transfer performance to the side c (thickness direction) in anisotropic graphite. (A3) means that it is important to set the thickness of the inorganic material layer.

From the comparison between Example 2 and Example 6, (a1) oxygen-free copper is more suitable as the inorganic material layer (a3) bonded to the anisotropic graphite than the copper layer formed by electrolytic copper plating. I know that there is. This is because oxygen-free copper has better thermal conductivity than a copper layer formed by electrolytic copper plating.

From the comparison of Example 2, Example 7 and Example 8, (a1) the entire surface of the anisotropic graphite rather than (a3) the inorganic material layer being bonded only to the upper and lower surfaces of the anisotropic graphite (a1) It can be seen that the heat transfer performance of the semiconductor package is higher when (a3) the inorganic material layer is bonded. This is because (B) the heat from the semiconductor element can be diffused to the side surface portion of (a1) anisotropic graphite, and heat can be radiated more efficiently. Further, from the comparison between Example 7 and Example 8, the heat transfer performance of the semiconductor package is higher in the (a3) inorganic material layer using the bottomed frame than in the (a3) inorganic material layer using the hollow frame. I understand that it is expensive. This is because the (a3) inorganic material layer using the bottomed frame has fewer copper plate interfaces in the (a3) inorganic material layer.

From the comparison between Example 2 and Example 9, it was found that (a2) a part of the titanium-based active silver brazing which is the metal layer 7 exists in a part between the layers of the graphite layer of the anisotropic graphite (a1). It can be seen that the heat transfer performance of the semiconductor package is higher than the case where it does not exist. This is because the gap having low thermal conductivity formed between the graphite layers is filled with a titanium-based active silver braze having relatively good thermal conductivity.

As described above, one embodiment of the present invention includes the inventions shown in the following [1] to [9].
[1] A semiconductor package according to an aspect of the present invention is a semiconductor package including (A) an anisotropic graphite composite and (B) a semiconductor element,
(A) comprises (a1) anisotropic graphite, (a2) metal layer, and (a3) inorganic material layer,
(A1) and (a3) are joined by (a2),
X-axis, Y-axis orthogonal to X-axis, Z-axis perpendicular to the plane including X-axis and Y-axis,
The average value of the lengths of the four sides (side a) parallel to the X axis in (A) is La,
The average value of the lengths of the four sides (side b) parallel to the Y axis in (A) is Lb,
When the average value of the lengths of the four sides (side c) parallel to the Z axis in (A) is Lc,
The crystal orientation plane of the graphite layer forming the (a1) is parallel to the XZ plane including the X axis and the Z axis;
The length of the long side of (B) is l1,
The length of the short side of (B) is l2,
When the thickness of the (B) is l3,
(B) is joined to (a3) included in (A) so that the long side of (B) is perpendicular to the XZ plane including the X axis and the Z axis,
The ratio (La / l2) of the average value (La) of the lengths of the four sides parallel to the X axis in (A) and the length (l2) of the short sides in (B) is 3 or more.
[2] The (a3) is preferably copper.
[3] The thickness of (a3) is preferably 100 μm or more and 300 μm or less.
[4] The La is preferably 10 mm or more.
[5] The Lc is preferably 3 mm or less.
[6] It is preferable that the entire surface of (a1) is covered with the above (a3).
[7] The (a3) preferably includes a bottomed frame or a hollow frame and a lid.
[8] It is preferable that a part of (a2) is provided in at least a part of the interlayer of the graphite layer forming (a1).
[9] The (a1) is preferably produced by laminating a polymer film in multiple layers and then heat-treating it while pressing.

The present invention can be suitably used for a semiconductor package with high heat dissipation.

1 Anisotropic Graphite 2 Crystal Orientation Plane 3 Side (of Anisotropic Graphite Composite) a
4 Side (of anisotropic graphite composite) b
5 Side c (of anisotropic graphite composite)
6 Inorganic material layer 7 Metal layer 8 Semiconductor element 9 Cooler 10 Anisotropic graphite complex 20 Lid 21 Hollow frame 22 Bottomed frame 30 Semiconductor package 81 Long side of semiconductor element 82 Short side of semiconductor element

Claims

(A) a semiconductor package comprising an anisotropic graphite composite and (B) a semiconductor element;
(A) comprises (a1) anisotropic graphite, (a2) metal layer, and (a3) inorganic material layer,
(A1) and (a3) are joined by (a2),
X-axis, Y-axis orthogonal to X-axis, Z-axis perpendicular to the plane including X-axis and Y-axis,
The average value of the lengths of the four sides (side a) parallel to the X axis in (A) is La,
The average value of the lengths of the four sides (side b) parallel to the Y axis in (A) is Lb,
When the average value of the lengths of the four sides (side c) parallel to the Z axis in (A) is Lc,
The crystal orientation plane of the graphite layer forming the (a1) is parallel to the XZ plane including the X axis and the Z axis;
The length of the long side of (B) is l1,
The length of the short side of (B) is l2,
When the thickness of the (B) is l3,
(B) is joined to (a3) included in (A) so that the long side of (B) is perpendicular to the XZ plane including the X axis and the Z axis,
The ratio (La / l2) of the average value (La) of the lengths of the four sides parallel to the X axis of (A) and the length (l2) of the short sides of (B) is 3 or more.
Semiconductor package.
The semiconductor package according to claim 1, wherein (a3) is copper.
The semiconductor package according to claim 1 or 2, wherein the thickness of (a3) is not less than 100 µm and not more than 300 µm.
The semiconductor package according to any one of claims 1 to 3, wherein the La is 10 mm or more.
The semiconductor package according to any one of claims 1 to 4, wherein the Lc is 3 mm or less.
6. The semiconductor package according to claim 1, wherein the entire surface of (a1) is covered with the (a3).
The semiconductor package according to any one of claims 1 to 6, wherein (a3) includes a bottomed frame or a hollow frame and a lid.
The semiconductor package according to any one of claims 1 to 7, wherein a part of (a2) is provided at least partly between the layers of the graphite layer forming the (a1).
9. The semiconductor package according to claim 8, wherein (a1) is manufactured by laminating a polymer film in multiple layers and then performing heat treatment while pressing and pressing.