JP2001135753A - Semiconductor module substrate and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor module substrate which has superior thermal transfer and heat radiation characteristic in the area, where a semiconductor chip is mounted and can prevent cracking or the like resulting from thermal stress. SOLUTION: In a semiconductor module substrate for mounting a semiconductor chip 7, a heat sink 2, an insulation layer 4 formed on the heat sink 2 with a spraying method and a mixed layer 3 of a heat sink material and an insulation material formed with the spraying method to the interface area between the heat sink 2 and insulation layer 4 are provided and the element ratio of the mixed layer 3 is determined in a manner such that the heat sink material ratio is higher at the area near to the heat sink 2, while the insulation material ration is higher at the area near to the insulation layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor module substrate and a method of manufacturing the same, and more particularly, to a semiconductor module substrate such as a power module substrate for mounting a semiconductor chip which generates a large amount of heat and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a conventional semiconductor module substrate of this type, for example, a power module substrate as shown in FIGS. 4 and 5 is known. The power module substrate 11 shown in FIG. 4 is an insulating substrate 14 made of a ceramic substrate.
The wiring metal plate 16 is bonded to the upper surface of the insulating substrate 14 via the brazing material 15, while the heat sink 12 is bonded to the lower surface of the insulating substrate 14 via the brazing material 13.

In the power module substrate 21 shown in FIG. 5, an insulating substrate 25 made of a ceramic substrate is bonded on a heat sink 22 via a brazing material 23, and a wiring metal plate 26 is further formed on the insulating substrate 25. DBC (Direct
It has a structure in which a DBC substrate 24 directly bonded by a bonding copper method is bonded.

[0004] Such a power module substrate 11
In (21), the semiconductor chip 7 is mounted on the wiring metal plate 16 (26), and a pad electrode (not shown) formed on the upper surface of the semiconductor chip 7 and a pad electrode portion 16a (26a) of the wiring metal plate 16 (26). ) Are bonded by a wire 18 (28).

[0005]

The semiconductor module substrate, especially when used as a power module substrate, has excellent heat radiation characteristics since the mounted semiconductor chip 7 generates a large amount of heat when a large current flows. Is required. For this reason, the insulating substrate 14 (25) located between the semiconductor chip 7 and the heat sink 12 (22) also has excellent heat radiation characteristics.
That is, it is required to have high thermal conductivity.

In a semiconductor module substrate such as a power module substrate, a difference in thermal expansion coefficient between components occurs due to a periodic temperature change (temperature cycle) due to operation / pause of a mounted semiconductor chip. Thermal stress is generated. If the thermal stress is excessive, cracks or the like may occur in the insulating substrate or the semiconductor chip, and the reliability may be reduced. For this reason, it is important to match the coefficients of thermal expansion between components to reduce thermal stress.

However, for example, a heat sink (Cu: thermal expansion coefficient: 17.7 × 10 ⁻⁶ / K) having a high heat radiation characteristic is bonded to an insulating substrate (AlN: thermal expansion coefficient: 4.5 × 10 ⁻⁶ / K). In such a case, the difference in thermal expansion between these materials is large, and peeling may occur at the interface or cracks may occur in the material, which may lower reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a semiconductor module substrate which has excellent heat radiation characteristics and can prevent the occurrence of cracks and the like due to thermal stress, and a method of manufacturing the same. The purpose is.

[0009]

In order to achieve the above object, a semiconductor module substrate (1) according to the present invention comprises a semiconductor module substrate for mounting a semiconductor chip, wherein the heat sink comprises a heat sink; An insulating layer formed thereon by a thermal spraying method, and a mixed layer of a heat sink material and an insulator material formed by a thermal spraying method at an interface between the heat sink and the insulating layer,
A portion of the mixed layer near the heat sink has a higher heat sink material, and a portion closer to the insulating layer has a higher insulator material.

[0010] According to the semiconductor module substrate (1), the inclined structure in which the component ratio of the heat sink material to the insulator material is changed in the layer thickness direction between the heat sink and the insulating layer. Since the mixed layer, that is, the thermal stress relaxation layer is interposed, thermal stress caused by a difference in thermal expansion coefficient between the heat sink and the insulating layer is reduced, and cracks and the like are prevented from being generated in the insulating layer. Can be.

[0011] The semiconductor module substrate (2) according to the present invention, in the semiconductor module substrate (1), comprises a metal layer formed on the insulating layer by a thermal spraying method.
At the interface between the insulating layer and the metal layer, a mixed layer of an insulator material and a metal material formed by thermal spraying,
The portion where the component ratio of the mixed layer is close to the insulating layer is high in the insulator material, and the portion close to the metal layer is high in the metal material.

According to the semiconductor module substrate (2), the inclined structure in which the component ratio between the insulator material and the metal material is changed in the layer thickness direction between the insulating layer and the metal layer. Since the mixed layer, that is, the thermal stress relaxation layer is interposed, the thermal stress caused by the difference in thermal expansion coefficient between the insulating layer and the metal layer is relaxed, and the occurrence of cracks and the like in the insulating layer is prevented. can do.

Further, according to a method of manufacturing a semiconductor module substrate according to the present invention, there is provided a method of manufacturing a semiconductor module substrate for mounting a semiconductor chip, wherein a mixed heat spray of a heat sink material and an insulator material is performed on a heat sink. Forming a mixed layer of the heat sink material and the insulator material, and spraying the insulator material on the mixed layer, thereby forming an insulating layer. In forming the mixed layer by thermal spraying, the supply ratio of the heat sink material is increased in a portion close to the heat sink, and the supply ratio of the insulator material is increased in a portion close to the insulating layer formed thereon. It is characterized by going.

According to the method (1) for manufacturing a substrate for a semiconductor module, the component ratio between the heat sink material and the insulator material is changed between the heat sink and the insulating layer in the layer thickness direction. A semiconductor module substrate in which the mixed layer having the inclined structure, that is, the thermal stress relaxation layer is interposed can be manufactured. Therefore, a thermal stress caused by a difference in thermal expansion coefficient between the heat sink and the insulating layer is reduced, and a semiconductor module substrate that can prevent cracks and the like from occurring in the insulating layer can be realized.

Further, according to a method of manufacturing a semiconductor module substrate according to the present invention, in the method of manufacturing a semiconductor module substrate, a mixed spray of an insulator material and a metal material is formed on the insulating layer. Performing a mixed layer of the insulator material and the metal material, and spraying a metal material on the mixed layer, thereby forming a metal layer. In forming the mixed layer, the supply ratio of the insulator material is increased in a portion close to the insulating layer, and the supply ratio of the metal material is increased in a portion close to the metal layer formed thereon. It is characterized by going.

According to the method (2) for manufacturing a substrate for a semiconductor module, between the insulating layer and the metal layer,
It is possible to manufacture a semiconductor module substrate in which the mixed layer having an inclined structure in which the component ratio of the insulator material and the metal material is changed in the layer thickness direction, that is, the thermal stress relaxation layer is interposed. Accordingly, a thermal stress caused by a difference in thermal expansion coefficient between the insulating layer and the metal layer is reduced, and a semiconductor module substrate that can prevent the occurrence of cracks or the like in the insulating layer can be realized.

Further, in the method (3) for manufacturing a substrate for a semiconductor module according to the present invention, in the method (2) for manufacturing a substrate for a semiconductor module, the insulating layer is covered with a mask having a wiring pattern. Forming the mixed layer by performing mixed spraying of a body material and the metal material, and then performing spraying of the metal material on the mixed layer, thereby forming a metal layer serving as a wiring pattern. Features.

According to the method (3) for manufacturing a substrate for a semiconductor module described above, after the insulating layer is covered with a mask having a wiring pattern, mixed spraying of the insulator material and the metal material is performed. In order to form the mixed layer and then perform thermal spraying of the metal material on the mixed layer, a metal layer serving as a wiring pattern is formed in the same manner as the insulating layer, thereby simplifying a manufacturing process of a semiconductor module substrate. Can be achieved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a semiconductor module substrate and a method of manufacturing the same according to the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a semiconductor module substrate as a power module substrate according to an embodiment.

As shown in FIG. 1, in the semiconductor module substrate 1 according to the embodiment (1), a mixed layer 3 of a heat sink material and an insulator material formed by a thermal spraying method is interposed on a heat sink 2. Thus, an insulating layer 4 is provided. The heat sink 2 is made of, for example, Cu material, Al material, Mo
It is made of a material having a high thermal conductivity, such as a material, a W material, a Cu-Mo mixed material, a Cu-W mixed material, or the like.

The insulating layer 4 is made of, for example, an AlN material or Al ₂ O ₃
By spraying ceramic powder such as material, the film thickness becomes 0.3
It is formed to be about 2.0 mm. Further, the mixed layer 3 is formed by the heat sink material (Cu material,
Al material, etc.) and the above-mentioned insulator material (AlN material, Al ₂ O ₃ material, etc.) in a gradient structure (layer thickness: 0.0
The heat sink material is high in a portion near the heat sink 2 and the insulating material is high in a portion near the insulating layer 4.

A wiring metal layer 6 having a pattern is provided on the insulating layer 4 with a mixed layer 5 of an insulator material and a metal material formed by a thermal spraying method interposed.

The wiring metal layer 6 is made of, for example, Cu material, Al material,
It is formed by a thermal spraying method using a metal powder such as a Mo material so that the film thickness is about 0.1 to 0.5 mm.
In addition, the mixed layer 5 has the insulating material (AlN material,
Al ₂ O ₃ material) and the above-mentioned metal materials (Cu material, Al material, etc.)
Structure (layer thickness: 0.05-
The insulating material is high in a portion near the insulating layer 4 and the metal material is high in a portion near the wiring metal layer 6.

The semiconductor chip 7 is mounted on the wiring metal layer 6, and a pad electrode (not shown) formed on the upper surface of the semiconductor chip 7 and a pad electrode portion 6 a of the wiring metal layer 6 are bonded by wires 8. It has become so.

Here, Table 1 shows examples of combinations of the constituent materials of the insulating layer 4 and the wiring metal layer 6 when the heat sink 2 is made of Cu and Al, respectively, and the thermal conductivity of each material shown in Table 1 And the thermal expansion coefficient are shown in Table 2.

[0026]

[Table 1]

[0027]

[Table 2] Next, a method for manufacturing a substrate for a semiconductor module according to an embodiment of the present invention will be described.
This will be described with reference to FIG.

First, two kinds of powder materials composed of a powder of a heat sink material and a powder of an insulator material are mixed and sprayed on the heat sink 2 by a reduced pressure plasma spraying method (FIG. 2A). A mixed layer 3 of a heat sink material and an insulator material is attached and formed on the upper surface.

As for the powder supply ratio in performing the mixed spraying, the ratio of the powder of the heat sink material is increased in the portion close to the heat sink 2, and the ratio of the powder of the insulator material is increased as the thermal spraying proceeds.

Next, by spraying a powder of an insulating material on the mixed layer 3 (FIG. 2B), an insulating layer 4 is adhered and formed on the upper surface of the mixed layer 3, and A mask 9 having a wiring pattern is disposed at a predetermined position, and a mixed spraying of two kinds of powder materials composed of an insulator material powder and a metal material powder is performed on the insulating layer 4 (FIG. 2).
(C), a mixed layer 5 of an insulator material and a metal material is formed on the upper surface of the insulating layer 4 by adhesion.

The powder supply ratio for performing the mixed thermal spraying is to increase the ratio of the powder of the insulating material near the insulating layer 4 and to increase the ratio of the powder of the metallic material as the thermal spraying proceeds. .

Next, by spraying a metal material powder on the mixed layer 5 (FIG. 2D), a wiring metal layer 6 is attached and formed on the upper surface of the mixed layer 5 (FIG. 2E). And mask 9
Is removed to produce the semiconductor module substrate 1 shown in FIG.

According to the semiconductor module substrate 1 having the above structure, the mixed layer 3 having the inclined structure in which the component ratio of the heat sink material and the insulator material is changed in the layer thickness direction between the heat sink 2 and the insulating layer 4. That is, a mixed layer 5 having a gradient structure in which a component ratio between an insulator material and a metal material is changed in the layer thickness direction between the insulating layer 4 and the wiring metal layer 6, Since the stress relaxation layer is interposed, the difference in the coefficient of thermal expansion between the heat sink 2 and the insulating layer 4
The thermal stress caused by the difference in the coefficient of thermal expansion between the insulating layer 4 and the wiring metal layer 6 is reduced, and the occurrence of cracks and the like in the insulating layer 4 can be prevented.

In this embodiment, the heat sink 2
Has been described as an example in which Cu and Al are used as the metal material constituting the above, but in another embodiment, another material having high thermal conductivity may be used.

Further, in the above-described embodiment, an example has been described in which the semiconductor module substrate 1 is a power module substrate, but the present invention is applicable not only to a power module substrate but also to various semiconductor module substrates. Can be.

Further, in the above embodiment, only the semiconductor module substrate having the mixed layer 5 and the wiring metal layer 6 formed on the insulating layer 4 by thermal spraying has been described. Alternatively, a wiring metal plate may be bonded via a brazing material (Ag brazing material or the like).

[0037]

Examples and Comparative Examples Next, examples of the semiconductor module substrate according to the present invention will be described. In the embodiment, the constituent materials of the heat sink 2, the mixed layer 3, the insulating layer 4, the mixed layer 5, and the wiring metal layer 6 of the semiconductor module substrate 1 shown in FIG. To D. Samples of four types of semiconductor module substrates 1 were manufactured.

<Evaluation Sample> ・ Dimensions of heat sink 2: 140 mm × 70 mm × 3 mmt ・ Dimensions of mixed layer 3: 40 mm × 30 mm × 0.15 mmt ・ Material supply ratio (mixed layer 3): 90:10 (= heat sink material: insulator material). As the distance from the heat sink 2 increases, the insulator material is added and increased by 10%, and the supply ratio in the uppermost layer is 10:90. -Dimensions of the insulating layer 4: 40 mm x 30 mm x 0.6 mmt-Dimensions of the mixed layer 5: 40 mm x 30 mm x 0.15 mmt-Material supply ratio (mixed layer 5): The supply ratio in the lowermost layer is 90:10 ( = Insulator material: metal material), and as the distance from the insulating layer 4 increases, the metal material is added and increased by 10%, and the supply ratio in the uppermost layer is 10:90. -Thickness of the wiring metal layer 6: 0.3 mm After mounting the semiconductor chip 7 on each type A to D,
As shown in FIG. 3, the thermal resistance between the upper surface of the semiconductor chip 7 and the lower surface of the heat sink 2 was measured.

Further, a temperature cycle (T / C) test in which a temperature change from −65 ° C. → 150 ° C. → −65 ° C. is repeated 1000 times is performed, and the insulating layer 4 and the semiconductor chip 7 after the test are not peeled or cracked. Was evaluated. The thermal resistance ratio (relative ratio with the conventional example (type E) being 100) and the evaluation results after the temperature cycle test are also shown in Table 3.

Further, with respect to the power module substrate 21 having the conventional structure shown in FIG. 5, the constituent materials of the heat sink 22, the insulating substrate 25, and the wiring metal plate 26 were changed to the type E shown in Table 3.
Was manufactured as a combination shown in FIG.

<Evaluation Sample> Dimensions of heat sink 22: 140 mm × 70 mm × 3 mmt Thickness of brazing material 23: 0.1 mm Dimensions of insulating substrate 25: 40 mm × 30 mm × 0.6 mmt Joining of insulating substrate 25 and wiring metal plate 26 Part thickness: 0.1 mm Thickness of wiring metal plate 26: 0.3 mm After mounting semiconductor chip 7 on type E, measurement of thermal resistance and temperature cycle test were performed in the same manner as above as a comparative example. The results are shown in Table 3.

[0042]

[Table 3] As is clear from Table 3, in the types A to D of the semiconductor module substrate 1 according to the example, the thermal resistance value is lower than that of the type E having the conventional structure, and the heat generated in the semiconductor chip 7 is small. Was efficiently radiated by the heat sink 2.

In any of the types A to D according to the examples, no peeling or cracking was observed in the insulating layer 4 or the semiconductor chip 7. From the results of the temperature cycle test, the semiconductor module substrate 1 according to the example was obtained.
Was able to confirm that a reliability equal to or higher than that of the conventional semiconductor module substrate 21 was obtained.

From the above results, it was confirmed that a semiconductor module substrate having excellent heat radiation characteristics and high heat load reliability after mounting the semiconductor chip 7 can be realized.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a semiconductor module substrate according to an embodiment (1) of the present invention.

FIG. 2 is a side sectional view showing a part of the manufacturing process of the semiconductor module substrate according to the embodiment (1).

FIG. 3 is a schematic side cross-sectional view showing how to measure the thermal resistance of the semiconductor module substrate according to the embodiment (1).

FIG. 4 is a side sectional view showing an example of a conventional power module substrate.

FIG. 5 is a side sectional view showing an example of a conventional power module substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor module substrate 2 heat sink 3, 5 mixed layer 4 insulating layer 6 wiring metal layer 7 semiconductor chip

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shizuki Hashimoto 2701-1, Iwakura, Omine-cho, Omine-cho, Mine-shi, Yamaguchi F-term in Sumitomo Metal Electronics Device Co., Ltd. (reference) 4K031 AA06 AB03 AB04 AB05 BA06 CB10 CB14 CB35 CB41 CB43 CB46 5F036 AA01 BA23 BB08 BB21 BC24

Claims (5)

[Claims] 1. A semiconductor module substrate for mounting a semiconductor chip, comprising: a heat sink; an insulating layer formed on the heat sink by thermal spraying; and an interface between the heat sink and the insulating layer by thermal spraying. A mixed layer of the formed heat sink material and the insulator material, wherein the component ratio of the mixed layer is such that the portion near the heat sink has a higher heat sink material, and the portion near the insulating layer has a higher insulator material. A substrate for a semiconductor module, comprising: 2. A metal layer formed on the insulating layer by a thermal spraying method, and a mixed layer of an insulator material and a metal material formed by a thermal spraying method on an interface between the insulating layer and the metal layer. The component ratio of the mixed layer, wherein a portion close to the insulating layer is higher in the insulator material, and a portion closer to the metal layer is higher in the metal material. Substrate for semiconductor module. 3. A method of manufacturing a semiconductor module substrate for mounting a semiconductor chip, comprising: mixing and spraying a heat sink material and an insulator material on a heat sink. Forming a layer, and by spraying an insulator material on the mixed layer,
Forming an insulating layer; and forming the mixed layer by the mixed spraying.
For a semiconductor module, a supply ratio of the heat sink material is increased in a portion close to the heat sink, and a supply ratio of the insulator material is increased in a portion close to the insulating layer formed thereon. Substrate manufacturing method. 4. A step of forming a mixed layer of the insulator material and the metal material by performing mixed spraying of an insulator material and a metal material on the insulating layer; and forming a metal material on the mixed layer. Forming a metal layer by performing thermal spraying, and forming the mixed layer by the mixed thermal spraying.
The supply ratio of the insulator material is increased in a portion close to the insulating layer, and the supply ratio of the metal material is increased in a portion close to the metal layer formed thereon. 4. The method of manufacturing a semiconductor module substrate according to 3. 5. After the insulating layer is covered with a mask having a wiring pattern, the mixed layer is formed by performing mixed spraying of the insulator material and the metal material, and then forming the mixed layer on the mixed layer. 5. The method according to claim 4, wherein a metal layer serving as a wiring pattern is formed by spraying the metal material.