JPS63313842A - Substrate for mounting semiconductor device and semiconductor device - Google Patents

Abstract

PURPOSE:To contrive the improvement of the heat conductivity of the title substrate by a method wherein a metal layer for connecting a semiconductor element and a wiring layer are formed on the substrate consisting of a sintered body containing Al nitride as its main component. CONSTITUTION:A substrate consisting of a sintered body containing Al nitride as its main component is used as a substrate, which has a metal layer for connecting a semiconductor element and a wiring layer and is used for mounting a semiconductor device. That is, the Al nitride sintered body is easily formed to become dense in a high degree and has a high heat conductivity. However, the sintered body has a characteristic of having a high electrical resistivity and a low thermal expansion coefficient in combination by adjusting its composition. Thereby, a superior effect can be obtained by using the sintered body for a substrate for electrical insulation of a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION There are great demands for this, and the insulating substrate used is now required to be made of a material with good heat dissipation properties.

Conventionally, alumina sintered bodies have been used as a material for such insulating substrates, but alumina substrates have poor heat dissipation properties, so in order to achieve this purpose, insulators with higher heat dissipation properties are used. There was a need to develop substrate materials.

Such insulating substrate material θ) as (1) High electrical insulation.

(2) High thermal conductivity.

(3) The coefficient of thermal expansion is close to that of silicon.

(4) High mechanical strength.

(5) Low dielectric constant.

etc. are required.

The thermal expansion coefficient of the aluminum nitride sintered body is approximately s x
1 o-'/l:'', about 7X that of the alumina sintered body
It is smaller than 10"/U, close to the thermal expansion coefficient of silicon &3xlO"'/r, and has a bending strength of about 50
Kg/1xg” or more, and the alumina sintered body has approximately 2
It has extremely high strength compared to "0 Kg/ws".It also has excellent electrical insulation properties.

Conventionally known methods for producing aluminum nitride sintered bodies include (1) reaction sintering method, (2) pressureless sintering method, and (3) hot press sintering method. Among these methods, the reactive sintering method is a method in which a metal aluminum compact is sintered while undergoing a nitriding reaction in a nitrogen gas atmosphere. In the reactive sintering method, the nitriding reaction is rate-determined by the diffusion of nitrogen gas, so in the case of thick products, unreacted metal remains in the center, and because the product is porous, it has not been put to practical use as an electrical insulating material. . In the pressureless sintering method, yttrium oxide and rare earth oxides are added to aluminum nitride powder.
A method is known in which yttrium oxide and powders of silicon dioxide, nickel, calcium oxide, etc. are added and mixed and then fired to form a molded body. Furthermore, in the hot press sintering method, powders such as aluminum oxide, yttrium oxide, and silicon dioxide are added to aluminum nitride powder, mixed, formed into a compact, and then heated and sintered under pressure. According to the conventionally known pressureless sintering method and hot press sintering method, a densified aluminum nitride sintered body can be obtained, and the sintered body has high strength, electrical insulation properties, and a low coefficient of thermal expansion. However, the thermal conductivity of the sintered body obtained by the above method is low, usually 0.07 Ca17m-(6)・C(
room temperature), and even large ones are 0.1 Cat/Saw/Category/C. From these points, if aluminum nitride sintered bodies with higher thermal conductivity were developed, they would be useful as insulating substrate materials for large-scale integrated circuits and semiconductor devices.

It has a semiconductor element and a wiring layer, and these are lead wires.
As described above, the aluminum nitride sintered body has an electrical resistivity at room temperature of 1012 Ω steel or more, an average thermal expansion coefficient of 6 A powder obtained by adding beryllium and a beryllium-containing substance, preferably an amount of beryllium in the compound preferably from 0.05 to 100% by amount of beryllium in the compound, to aluminum nitride powder having a diameter of 20 μm or less is press-molded, and the mixture is press-molded in a non-oxidizing atmosphere. Pressureless sintering at a temperature of 1600~2000c, or sintering at a temperature of 16oo~2000r and 1
It can be obtained by hot pressing under pressure of 0.00 Kg/cWt" or more and sintering for a time sufficient to obtain a density of 90% or more of its theoretical density.

The amount of beryllium added in the present invention is preferably α05 to 10% by weight. 0.05 to obtain a densified sintered body
The coefficient of thermal expansion of the sintered body is preferably 6 x
In order to make it 10-''/C or less, it is preferably 10% by weight or less. It is particularly suitable when used as an insulating substrate for silicon semiconductor devices.

The beryllium to be added is beryllium, beryllium nitrate, beryllium sulfate, beryllium carbonate, beryllium phosphate, beryllium hydroxide, beryllium halide, beryllium acetylacetone, beryllium oxalate, beryllium carbide, beryllium boride, beryllium silicide, beryllium nitride, beryllium oxide. A beryllium-containing substance consisting of a beryllium compound such as

The average particle size of the aluminum nitride powder is preferably 20 μm or less, preferably 104 μm or less. Sintering of the aluminum nitride powder compact containing bobeIJIJium or a material containing BetaIJIJium is performed using a non-oxidizing method. Preferably done in a noisy atmosphere. In an oxidizing atmosphere, aluminum nitride is oxidized, making it difficult to obtain a desired sintered body.

Sintering temperature is 1600-2000C, preferably 170C
0 to 1900C is valid. The temperature is preferably 1600C or higher to obtain a dense sintered body, and 20C or higher to prevent superphosphoric acid.
001:' or less is preferable. The sintering may be performed by a pressureless sintering method or by a hot press method. If a sintered body is manufactured using the hot pressing method using negative-axis pressure, shrinkage will only occur in the axial direction of the press, resulting in higher dimensional accuracy and higher strength than the sintered body produced using the pressureless sintering method. A sintered body having the following properties can be obtained. In the hot press method, the upper limit of the applied load is determined by the material of the die used, but 100K
t/taku! If the above load can be applied, a desired sintered body can be obtained. The sintering time depends on the particle size of the raw powder,
The optimum value is determined by the type and amount of beryllium or beryllium-containing substance added, temperature, presence or absence and magnitude of load applied during sintering. In general, when the particle size of the raw material powder is small, the temperature is high, and a load is applied during sintering, a dense sintered body can be obtained in a shorter time, especially when the load is thicker. There are some differences in the type and amount of beryllium or beryllium-containing substances.

Practical Example 1 0.03 to 30% by weight of aluminum oxide powder with an average particle size of 3 μm was added to aluminum nitride powder with an average particle size of 2 μm and mixed. Then, the mixed powder was heated to 100% at room temperature.
A pressure of 0 Kf/z" was applied to form a molded body. The molded body was then placed in a firing furnace at a reduced pressure of lXl0-" to IX10-1.
Sintered in torr. Heating from room temperature to 1800t:
The temperature was raised to 1800 t in about 1 hour, maintained at 1800 t for 0.5 hours, and then allowed to cool. The relationship between the characteristics of the aluminum nitride sintered body produced as described above and the beryllium content in the sintered body is shown in FIGS. 1 to 4.

According to the results shown in Figures 1 to 4, when the amount of beryllium contained in the aluminum nitride sintered body is 0.05 to 25% by weight, a high heat of 0.3 cab/cWl・8・C or more is generated. Conductivity and electrical resistivity of 1012Ω or higher can be obtained, and 1
A densified sintered body having a low coefficient of thermal expansion of 6×10″″/C or less at α5% or less and a density of 90% or more of the theoretical density of the sintered body is obtained.

Actual example 2 Beryllium oxide powder for aluminum nitride powder
A molded body was obtained from the mixed powder to which % by weight was added, and the sintered body was manufactured in vacuum by changing the sintering conditions.

Table 1 is a table showing the relationship between the manufacturing conditions of the sintered body and the relative density of the obtained sintered body. When the relative density of the obtained sintered body is 90% or more, the thermal conductivity (room temperature) of 0.4 Cat/S-C or higher and the electrical resistivity of 10Ω/1 or higher are achieved. (room temperature) and 42 to 4.3 x 10”/
It had a coefficient of thermal expansion of r (average value from room temperature to aoor).

Experimental example 3 Beryllium oxide powder was added to aluminum nitride powder by 3
A molded body was obtained from the mixed powder to which wt% was added, and an actual experiment @1 was carried out.
A sintered body was obtained in the same manner as described in . In this example, the atmosphere during the production of the sintered body was varied among argon gas, helium gas, nitrogen gas, and hydrogen gas. All of the obtained sintered bodies had the same performance as the sintered body described in Experimental Example 1 in which the per-17ium content was 1% by weight.

Experimental Example 4 For aluminum nitride, beryllium metal or beryllium nitrate, beryllium sulfate, beryllium carbonate, beryllium phosphate, beryllium hydroxide, beryllium halide,
Beryllium acetylacetone, beryllium oxalate, reconstituted beryllium, beryllium chloride, beryllium silicide,
0.03 to 1 as beryllium, a type of beryllium nitride
0% by weight was added and mixed, and a sintered body was produced in the same manner as in Experimental Example 1. The obtained sintered body is densified to a relative density of 90% or more when beryllium or beryllium in a beryllium-containing compound is added in an amount of 0.05% or more, and has the same performance as the sintered body described in many experiments. Shown in Table 1, No. 2.

Experimental Example 5 A sintered body was obtained in the same manner as in Experimental Example 1 by adding and mixing 3% by weight of beryllium oxide powder to aluminum nitride powders having different average particle sizes. As shown in Table 2, the relative density of the obtained sintered body was determined by the average particle size of the aluminum nitride powder being 204 m.
It has 90% or more in the following cases. A sintered body whose relative density is 90% or more is 0.4 Cat/crIM・S
-1: Thermal conductivity (room temperature) of l' or more, 1o1! It had an electrical resistivity (room temperature) of Ω·α or more and a thermal expansion coefficient (average value from room temperature to 300 C) of 42 to 4.3×10−/C.

EXAMPLE As a specific application example of the present invention, a semiconductor power module will be described in which the electrically insulating aluminum nitride sintered body obtained in Example 1 and having a beryllium content of 1% by weight is used as an insulating substrate. . FIG. 5 is an assembled sectional view of the conventional structure. An organic insulator 5 and an alumina substrate 7 are used to insulate between the conductor 4 and the heat 7/rear 6 and between the heat seal and the metal support plate 8, and between the silicon element 1 and the heat sink 6.
A molybdenum spacer 3 is interposed in order to alleviate the strain caused by the difference in thermal expansion coefficient between the two.

FIG. 6 is an assembly diagram of a semiconductor power generator using the aluminum nitride sintered body of the present invention as an insulating substrate. The insulating substrate 15 is directly attached to the silicon element 11 by brazing, and by using the sintered body of the present invention, an extremely simple structure can be obtained.

A heat cycle test was conducted on the above semiconductor device by holding it at -600 for 30 minutes, then holding it at room temperature for 5 minutes, then raising the temperature to 125C and holding it for 30 minutes. In the conventional semiconductor device (FIG. 5), the solder joints 9 and 10 broke due to fatigue after 20 heat cycles. Although the semiconductor device of the present invention (FIG. 6) shows no abnormalities even after 150 heat cycles, it tends to be highly densified and has high thermal conductivity.

Furthermore, by adjusting the composition, it has the characteristics of having both high electrical resistivity and a low coefficient of thermal expansion.

Therefore, excellent effects can be obtained by using it as an electrically insulating substrate for a semiconductor device as described above. Further, the sintered body of the present invention is suitable as a member that requires heat resistance, oxidation resistance, corrosion resistance, and chemical resistance, a member that requires thermal shock resistance, and a member that requires high strength at high temperatures.

[Brief explanation of the drawing]

Figure 1 shows beryl-17ium content and relative density of sintered body/IA
Figure 2 shows the relationship between the beryllium content and the thermal conductivity of the sintered body (room temperature), Figure 3 shows the relationship between
Figure 4 shows the relationship between the Jium content and the electrical resistivity (room temperature) of the sintered body.
300C), FIG. 5 is an assembled sectional view of a conventional silicon semiconductor device, and FIG. 6 is an assembled sectional view of a silicon semiconductor device using the sintered body of the present invention as a substrate. l and 11... silicon element, 2 and 12... lead wire, 3... molybdenum spacer, 4 and 13...
Conductor, 5... Organic insulator, 6... Heat sink, 7
...Alumina substrate, 8...Support plate, 9.10 and 1
4...Solder, 15...Aluminum nitride sintered body substrate. Agent JiF Physician Ogawa pjj Male (/,)X/z
與9↓

Claims (1)

[Scope of Claims] 1. A semiconductor device board, characterized in that a metal layer for connecting semiconductor elements and a wiring layer are formed on a sintered substrate mainly composed of aluminum nitride. 2. The substrate for mounting a semiconductor device according to claim 1, wherein the sintered body contains beryllium or a beryllium-containing substance in an amount of 0.05 to 10% by weight. 3. The thermal conductivity of the sintered body at room temperature is 0.3 cal/cm.
- The substrate for mounting a semiconductor device according to claim 1 or 2, wherein the average coefficient of thermal expansion from s·°C or higher and from room temperature to 300°C is 6×10^-^6/°C or less. 4. A semiconductor device, characterized in that a semiconductor element and a wiring layer are provided on a sintered substrate mainly composed of aluminum nitride, and the semiconductor element and the wiring layer are electrically connected by a lead wire. 5. The thermal conductivity of the sintered body at room temperature is 0.3 cal/cm.
- The semiconductor device according to claim 4, wherein the average coefficient of thermal expansion from room temperature to 300°C is 6×10^-^6/°C or less. 6. The semiconductor device according to claim 4 or 5, wherein the sintered body contains beryllium or a beryllium-containing substance in an amount of 0.05 to 10% by weight.