JPS6221247A - Electrically insulating substrate for semiconductor device - Google Patents

Abstract

PURPOSE:To improve the heat resistance of an insulating substrate by forming an insulating layer containing a specific inorganic oxide on a metal plate by means of a physical vapor phase evaporation method. CONSTITUTION:An insulating layer containing more than one kind of Al2O3, SiO2, Ta2O5, TiO2, ZrO2 and Y2O3 and 5-95wt% MgO is formed on a metal plate by means of a physical vapor phase evaporation method, e.g, the ion implating method. And this insulating layer is vapor-deposited to a thickness of 0.5-20mum under the vacuum condition not greater than 10<-4>Torr. With this structure, the heat dissipation becomes better since a thin insulating layer is formed on a metal plate, and the heat resistance improves since MgO is contained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an insulating substrate for semiconductor devices. More specifically, the present invention relates to an insulating substrate for a semiconductor device having a two-layer structure of an electrically insulating coating and a metal substrate, which has good heat dissipation and insulation properties as well as high heat resistance.

BACKGROUND OF THE INVENTION Semiconductor devices and apparatuses and equipment using these devices have complex thermal systems due to heat generation in active elements such as semiconductor elements and passive elements such as resistors and coils. However, semiconductor devices generally have a maximum permissible temperature from the viewpoint of their characteristics and reliability, and also a permissible range of temperature differences within the device or between devices from the standpoint of noise margin.

Therefore, in order for these elements to operate stably and with high reliability, it is necessary to have the best thermal design.

Furthermore, in recent years, the technology for manufacturing semiconductor devices has made dramatic progress, as exemplified by the miniaturization and increased performance of combinators. As the speed of operation and the degree of integration of semiconductor devices have increased, and the density of wiring has increased accordingly, the amount of heat generated has increased accordingly, and it is necessary to develop countermeasures for this. That is, in order to dissipate the heat generated by semiconductor elements and the like, excellent semiconductor device packages and circuit boards that have good heat dissipation properties are becoming essential.

As a conventional electrically insulating substrate for mounting semiconductor elements, A
1□03 has been mainly used, but this Al
2O3 cannot necessarily be said to be satisfactory in terms of thermal conductivity.

In addition, the use of e○, which has good thermal conductivity, is also known, but this material has problems such as being toxic and expensive, and there is a limit to the amount of supply. Not used much.

On the other hand, Cu -WSCu-Mo, Cu -W-
Powder sintered bodies such as Mo, W, Mo, and various Cu alloys and Ni alloys are highly thermally conductive metals, but because they are conductive metals and alloys, they are used in semiconductors such as packages for semiconductor devices and circuit boards. When used as a device substrate, there are many restrictions, and it is necessary to provide electrical insulation by providing an electrically insulating coating layer on the surface. In other words, substrates for semiconductor devices are required to have high electrical insulation and high heat dissipation properties at the same time.
A device that simultaneously satisfies these two requirements is to increase the speed of semiconductor devices,
This can be said to be sufficient to cope with the increase in heat generated due to higher integration.

Therefore, a semiconductor device substrate with a laminated structure is created, in which a metal substrate that is electrically conductive but has high thermal conductivity is coated with a ceramic material that has good thermal conductivity and is also satisfactory in terms of electrical insulation. Proposed. Here, the ceramic material must have good adhesion to the metal and have a dense film quality, and it is said that the PVD method or CVD method is advantageous as the coating method.

Furthermore, the substrate for mounting a semiconductor device is heated to a temperature of 500°C to 90°C during packaging of the device, assembly and mounting of the circuit board.
Semiconductor device substrates are often subjected to fairly high temperature conditions of 00° C., so it is necessary to provide semiconductor device substrates with heat resistance that can withstand such high temperatures.

Problems to be Solved by the Invention As described above, there has been a recent trend toward higher speed and higher density in semiconductor devices, and with this, a new problem of increased heat generation has emerged.

This problem is an important issue that must be solved in the design and manufacture of semiconductor devices in parallel with increasing the speed and density of devices. Therefore, substrates for semiconductor devices in particular are required to have both high electrical insulation and high heat dissipation properties.

Furthermore, the substrate must be able to withstand high temperatures during packaging and assembly of semiconductor devices.
The heat resistance temperature of the conventionally proposed substrate consisting of a metal plate and an inorganic insulating film coated on the metal plate is at most 300-400℃.
00°C, and it was difficult to obtain the required heat resistance.

Developing a substrate for semiconductor devices that can meet these various demands and also achieve high reliability in practical use will improve the stability and reliability of semiconductor devices that are designed for high-speed, high-density packaging. It is extremely important to ensure that

Therefore, an object of the present invention is to efficiently dissipate the heat generated by semiconductor elements and devices, have sufficient heat resistance at high temperatures, and have good electrical insulation properties that guarantee the necessary dielectric strength voltage. An object of the present invention is to provide a substrate for mounting a semiconductor device that also provides high reliability.

Means for Solving the Problems The present inventors have discovered that the problem of low heat resistance of conventional substrates having a laminated structure of metal and inorganic insulators is caused by moisture contained in residual gas being released during the coating layer forming operation. We have learned that this problem is caused by MgO being mixed into the coating layer, and that this problem can be solved by reducing the residual gas in the vacuum, and furthermore, by incorporating MgO in a predetermined amount in the electrically insulating coating layer. The present invention was completed based on the discovery that the problem could be solved by the following.

1!11 H. The insulating substrate for a semiconductor device of the present invention includes a metal plate, a metal plate, and a substrate, and contains 5 to 95% by weight of MgO, which is provided by a physical vapor deposition method. Al2O
:l, 5102, Ta2O, TlO2, ZrO2 and Y203.

In the electrically insulating substrate of the present invention, the metal plate itself must be selected from materials that have high thermal conductivity. In order to ensure sufficient heat dissipation, it is preferable to use a material having a thermal conductivity of 0.2 Cal/cm -sec, .degree. C. or higher. Cu-W, Cu-Mo, Cu
- There are alloys such as W-Mo or powder sintered bodies. Others Fe Ni alloy, Ni alloy, 5fJS plate, Mo, W
Of course, it is also possible to use a metal plate such as.

The electrically insulating substrate for semiconductor devices of the present invention can be obtained as follows. That is, on the metal plate, 1υ−”I'
It can be formed by depositing an insulating material raw material under a vacuum condition of less than orr or more according to a physical vapor deposition method (PVD method), for example, an electron beam evaporation method, an ion blating method, a) X&Fettang method, or the like. At this time ＼ 8l 20 ],
S Io2, Ta2O3, TlO2, ZrO2, Y
As a method for incorporating 1Ag○ into the coating layer of an inorganic oxide such as 2O3 or a mixture thereof, the coating may be formed by simultaneous supply from two sources: a source of only 1Jg○ and a source of other components. There are two possible methods of forming a film using a single source consisting of a mixture of 1.1g or 1.1g○ and other components, both of which give favorable results.

It should be noted that an insulating film can be selectively formed on the entire surface of the metal plate or only on a part thereof, if necessary, and the coating layer may be in either a crystalline state or an amorphous state.

] High heat dissipation, high electrical insulation, and good high-temperature heat resistance are required for substrates that can be fully put into practical use for semiconductor devices that have recently become faster and more integrated. Ru.

In the substrate of the present invention, requirements regarding heat dissipation and electrical insulation are met based on the combination of a metal plate having good thermal conductivity and the above-mentioned inorganic oxide having high insulation and thermal conductivity. is fully satisfied. On the other hand, high-temperature heat resistance can be achieved by incorporating a predetermined amount of Mho into the electrically insulating coating layer.

In other words, the reason why conventional substrates of this type could not achieve sufficient heat resistance is that during the operation of forming a coating with an electrically insulating material, H2C contained in the residual gas in the vacuum system is generated in the insulating film. The inventors have discovered that 820 is mixed in a relatively large amount, and therefore, when the substrate is placed under high temperature conditions, 820 in the coating layer is released, and at the same time, the coating layer shrinks in volume and cracks occur. This has been revealed through research. This crack may further cause oxidation of the underlying metal through the gap.
In this sense, sufficient heat resistance cannot be obtained, and the reliability of the substrate is also impaired. In this way, the internal stress of the coating layer containing F(20) is tensile stress.

By the way, as means for improving the heat resistance of the substrate, the following two methods can be considered. That is, one method is to reduce the amount of H2C mixed into the coating layer by reducing as much as possible the amount of residual gas in the vacuum system when forming the coating layer, and the other method is to reduce the amount of H2C mixed into the coating layer. ), )g○ is used.

When MgO is used as an insulating film material, even if the coating operation is performed in a vacuum system with a high H20 partial pressure, H2 will not enter the film.
The amount of zero-mixed artifacts is extremely small, and the internal stress of the resulting layer is also compressive stress. However, the heat resistance that can be achieved with a coating layer made only of MgO is about 600° C. at most, which is still not sufficient.

However, A1.03 containing 5 to 95% by weight of MgO
, SiO2, Ta2O:+, TlO2, Z'02, Y
It has been found that heat resistance is greatly improved when an electrical insulating film made of 2O3 or a mixture thereof is used. Such high heat resistance makes the insulating film 10-4T
The same effect can be achieved even when the coating is performed under a high residual gas pressure of about 0.05 to 10.0 m. In this case, even though the coating layer contains a small amount of 820, the resulting coating film exhibits high heat resistance of 800 t- or more, and the internal stress is also known to be compressive stress.

In the present invention, when it is intended to provide a semiconductor mounting substrate with sufficient heat resistance against high temperatures of 800°C or higher, the content of MgO in the coating layer must be within the range of 5 to 95% by weight. . That is, if it is less than the lower limit of 5%, AI□Ot, 5102, Ta2C1+T 10
2.1 The characteristics of components other than MgO such as rO2 and Y2O3 appear strongly, making it impossible to secure the desired sufficient heat resistance.On the other hand, when used in excess of the upper limit of 95% by weight, MgO cannot be used as a single coating layer. Both are unfavorable because the characteristics are strongly expressed and sufficient heat resistance cannot be ensured.

Furthermore, in order to obtain an electrically insulating substrate with the desired heat resistance, the formation of an insulating film on the substrate must be performed by the PVD method under vacuum conditions of 10-4 Torr or less as described above. is essential, and a particularly significant effect can be expected from this.

From the above, the high temperature heat resistance of the base 1 roll of the present invention is M
These properties are the result of a synergistic effect between gO and other components such as A I 203.8102.

Further, the thickness of the electrically insulating coating layer needs to be within the range of 0.5 to 20 μm. In other words, if the insulating layer is provided with a thickness exceeding the upper limit of 20 μm, there is a risk that cracks may occur in the coating layer due to the internal stress of the coating layer itself, and if the thickness is less than the lower limit of 0.5 μm, , cannot ensure sufficient dielectric strength, and cannot guarantee sufficient reliability as a substrate for a semiconductor device.

EXAMPLES The electrical insulating substrate for a semiconductor device of the present invention will be explained in more detail by the following production examples, and the effects thereof will be demonstrated. However, the following examples are merely illustrative and do not limit the scope of the present invention in any way.

Production example: Using the ion blating method, 42% Ni-P
e On the alloy plate, Al2O3, SiC2, Ta2O3 respectively.
, Y2O3 and MgO were formed. These are made by melting each sintered body with an electron beam under a vacuum condition of I X 10-4 Torr or less, and
○ of orr.

It is evaporated in plasma to form a coating layer.

Further, 02 plasma was generated by high frequency, and the thickness of all coating layers was 2 μm.

In addition, 30% by weight of 51gQ and 70% by weight
(7) Using a mixed sintered body of 203.30% by weight of MgO and 70% by weight of S1O2, 30% by weight of MgO and 70% by weight of Y2O1, each coating layer was formed according to the above method. A substrate for a semiconductor device according to the present invention was obtained.

Further, a dual evaporation source was provided and a coating layer of MgO-A1203 with a mixing ratio of 1:1 was formed according to the above procedure.

Each sample thus obtained was heated in the atmosphere and the discoloration of the coated 42% Ni-Fe alloy was observed. The temperature immediately before the appearance of discoloration was recorded as the heat resistance temperature, and the results are shown in Table 1 below. Indicated. In addition, the measured temperature is 200 to 1.000
℃ at 100℃ intervals.

As is clear from the results in Table 1, it can be seen that the coating layer containing MgO exhibits particularly high heat resistance (about 800° C. or higher). Note that even after the above heat resistance test, there was no change in the electrical properties of the coating layer, and a dielectric strength voltage of 100 V could be achieved with a coating layer thickness of 2 μm. Therefore, it can be seen that the electrically insulating substrate for semiconductor devices according to the present invention is sufficiently durable for practical use.

Effects of the Invention As will be explained in detail above, the electrically insulating substrate for semiconductor devices of the present invention contains MgO and Al2O3,510.
2. The insulating layer is formed by combining Ta2O3, zrO2, Y20, or a mixture thereof, and is composed of a metal plate, which reduces heat generation as semiconductor devices become faster and more highly integrated. It has characteristics that can sufficiently cope with the increase in In addition, by using MgO,
The high-temperature heat resistance is improved, and no problems occur even when exposed to high temperatures during semiconductor packaging, circuit board assembly, etc.

Therefore, the semiconductor device mounting substrate of the present invention can be used for mounting and mounting various semiconductor devices, as well as IC5LSI and VLSI, which have remarkable high speed and high integration, and are characterized by high reliability.

Claims (4)

[Claims] (1) Metal plate and Al_2O_3 provided on it,
SiO_2, Ta_2O_3, TiO_2, ZrO_2
An electrically insulating substrate for a semiconductor device, comprising an insulating layer containing at least one oxide selected from the group consisting of Y_2O_3 and MgO and formed by physical vapor deposition. (2) The electrically insulating substrate for a semiconductor device according to claim 1, wherein the MgO is contained within a range of 5 to 95% by weight. (3) The electrically insulating substrate for a semiconductor device according to claim 2, wherein the thickness of the insulating layer is within the range of 0.5 to 20 μm. (4) The insulating layer obtained by the physical vapor deposition method is
The electrically insulating substrate for a semiconductor device according to any one of claims 1 to 3, which is formed under a vacuum condition of 10^-^4 Torr or less.