JPS61102744A - Substrate for semiconductor substrate and manufacture thereof - Google Patents

Abstract

PURPOSE:To form a substrate, which is hardly affected by heat cycles extending over a large number of times and has long lifetime, by interposing a thin-film layer consisting of alumina between a metallic plate and an evaporating insulating film through foundation treatment. CONSTITUTION:The manufacture is characterized by the formation of a thin- layer 3 composed of alumina between a metallic plate 1 and an inorganic insulating coating layer 2, and adhesive properties between the metallic plate 1 and the coating layer 2 in a product acquired by the interposing layer 3 are improved largely, thus shaping an electric insulating and heat-dissipating substrate, adhesive properties thereof are not deteriorated even by a heat cycle test and which has long lifetime. The thickness of the alumina sheet 3 as the interposing layer must be kept within a range, preferably, 0.05-0.3mum, and the thickness of the coating layer 2 must be maintained within a range, preferably, 5-10mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application The present invention relates to a substrate for a semiconductor device and a method for manufacturing the same, particularly a substrate for mounting a semiconductor device that can efficiently dissipate heat generated by a semiconductor device and has high electrical insulation properties. Basic it and its v
This relates to the A construction method.

Conventional technology Semiconductor devices, devices, and equipment that use these devices construct complex thermal systems due to heat generation in semiconductor elements, resistors, coils, etc., but such heat is transmitted through various heat conduction modes,
For example, it will be released outside the device by heat conduction, heat radiation, convection, etc.

In general, semiconductor devices have a maximum permissible temperature (maximum allowable temperature) from the standpoint of characteristics and reliability, and also a permissible range of temperature differences within the device or between devices from the standpoint of noise margin. do.

Therefore, in order to operate these elements stably and reliably, it is extremely important to perform the best thermal design in the design and manufacture of semiconductor devices and the like.

Furthermore, in recent years, there has been a trend toward faster speeds, higher densities, and larger sizes of semiconductor devices, and with this, an increase in the amount of heat generated by semiconductor devices has become a major problem. Therefore, there is a demand for improved heat dissipation of substrates for semiconductor devices, that is, further improvement of thermal conductivity in the thickness direction of the entire substrate. Therefore, substrates for semiconductor devices are required to have high electrical insulation and high heat dissipation properties at the same time.

However, none of the conventionally used semiconductor device substrates satisfies the above two characteristics at the same time. For example, sintered ceramics such as A1□03.2Mg0・S+02 are widely used because they have stable electrical insulation properties, but although such ceramics are satisfactory in terms of insulation properties, It had poor thermal conductivity and did not satisfy the requirements for heat dissipation. In some cases, highly thermally conductive metal materials such as W, Mo, and Cu are used as materials for semiconductor devices. However, since these metal materials are essentially conductive materials, they have problems with electrical insulation, and are subject to significant restrictions in the design and use of semiconductor devices. Furthermore, some attempts have been made to use BeO because it has both electrical insulation and a certain degree of heat dissipation, but it has not been widely used because it is expensive and toxic.

In order to eliminate the above-mentioned drawbacks, attempts have been made to utilize a composite material that combines a metal plate with good thermal conductivity and an inorganic material with good electrical insulation such as glass or ceramic. However, if these are combined using the general method shown below, it will be extremely difficult to obtain a substrate that has both sufficiently high electrical insulation and heat dissipation properties. .

That is, for example, one of the above-mentioned general methods is to cover a metal plate with glass by screen printing. However, in order to form a glass layer with sufficient electrical insulation without pinholes using this screen printing method, it is necessary to form the glass layer with a thickness of 15 μm or more. This will significantly impair the heat dissipation properties of the printed circuit board.

In addition, when making a composite by brazing, it is necessary to prepare a ceramic thin plate in advance, but the ceramic plate
Currently, it is technically impossible to manufacture the film with a thickness of less than μm, and high heat dissipation performance cannot be provided. Conversely, brazing may cause blowholes to form in the layer, which may further reduce thermal conductivity.

Furthermore, when coating a metal plate with an inorganic material using the plasma spraying method, it is difficult to obtain a base material with high heat dissipation properties.In other words, the JD layer formed by this method has a high In addition, since the layer itself is porous, the thickness of the coating layer must be 30 μm or more to ensure sufficient electrical insulation, and if this requirement is to be met, the heat dissipation 1'F will be sacrificed, and conversely, if heat dissipation is to be maintained, efficiency will be insufficient.

There have also been attempts to form an electrically insulating layer made of oxide by oxidizing the surface of a metal plate.
Cu5N+, which is commonly used as this kind of metal plate
, Fe, AI, etc. are not preferable because they have poor electrical insulation properties. This is because among the metals mentioned above, Cu,
) h, In the case of Fe, this is due to the poor electrical insulation properties of these oxides themselves, and in the case of AI, the thickness of the alumite layer is increased to ensure a certain level of heat dissipation. Although it is necessary to suppress the thickness to 10 μm or less, since the alumite layer is porous, sufficient electrical insulation cannot be maintained with a thickness of 10 μm or less.

Under these circumstances, physical vapor deposition (PVD) or chemical vapor deposition (CVD) is applied to the surface of a metal plate with good thermal conductivity.
It has been proposed to form a thin layer of electrically insulating inorganic material by method D). The thin layer formed by this vapor phase method is (1) dense and therefore maintains electrical insulation even if it is thin, and (11) the metal plate and the inorganic material as the coating layer are arbitrarily selected and combined. It has the characteristics that it can be used as a metal plate, such as N1, Cu, Al;
Highly thermally conductive Cu alloy, Cu-clad stainless steel, copper-clad Kovar, sintered bodies mainly composed of Mo or W, and inorganic materials with good thermal conductivity such as B, N, and A.
l2O3, AIN, SIC, 513N4, Y2O1,2
Many examples using Mg0/SiC2, diamond, etc. have been reported.

By using this vapor phase deposition method, it has become possible to produce an excellent product that has both heat dissipation and electrical insulation properties as a substrate for semiconductor devices, but as a result of a long life test after IC mounting, this product also showed It was found that the following problems need to be improved.

That is, the coating layer formed by the PVD method or CVD method is
In general, the adhesion with metal plates is satisfactory, but in long-life tests such as thermal cycle tests (tests by repeatedly cooling at -65°C and heating at 1 g at 5°C), the adhesion deteriorates. I found out that it does. This seems to be because the vapor deposited substance and the substrate formed a strong metallic bond on the surface of the metal plate that did not cause any problems in the initial test.

Problems to be Solved by the Invention As detailed above, in the design and manufacture of semiconductor devices, there is a trend toward higher speeds and higher density, and with this, the problem of increased heat generation has arisen. However, this is an important issue that must be solved 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. However, none of the conventionally known products satisfies these two requirements at the same time, and although various improvement measures have been attempted, attempts to improve one characteristic impede the other. Up to now, no semiconductor device substrate with characteristics meeting the above requirements has been known.

It has also been proposed to obtain a substrate that has both of the above physical properties using a vapor deposition method, but it was also found in a long-life test that the bonding strength between the metal plate and the vapor-deposited film was insufficient, making it impractical for practical use. reliability has not yet been achieved.

Developing a substrate that meets these requirements is extremely important to guarantee the stability and reliability of semiconductor devices that are designed to achieve higher speeds and higher densities. There is a great demand for the development of

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a new method for manufacturing a substrate for mounting a semiconductor device, which can efficiently dissipate heat generated by a semiconductor element and is also electrically insulating. Furthermore, it is another object of the present invention to provide a substrate for a semiconductor device that is stable against thermal stress.

Means for Solving the Problems In view of the above-mentioned current state of substrates for mounting semiconductor devices, the inventors of the present invention have conducted thorough examination and research to develop the desired substrate, and have found that the substrate has electrical insulation and heat dissipation properties. We focused on the fact that it is advantageous to form an inorganic insulating material with high thermal conductivity by a vapor phase method in order to impart properties, and in order to solve the problem of adhesion between the vapor deposited layer and the metal plate. discovered that it is effective to interpose an alumina thin film between these, and completed the present invention.

That is, the substrate for a semiconductor device of the present invention includes a metal plate with good thermal conductivity, an alumina layer with a thickness of 0.5 μm or less on the metal plate, and an alumina layer with a thickness of 2 to 2 μm formed on the alumina layer. 15μm
It is characterized by being composed of a coating layer of an inorganic substance.

In the substrate of the present invention, the metal plate may include Cu and its alloy, A1 or its alloy; cladding of Cu and its alloy with He1 alloy; alloy having a low coefficient of thermal expansion, such as λ(0 or W alloy; λ1o or Examples include powder alloys such as W (which may contain Cu, AI, and Si), such as [u-15 to 20% Mo (or W).

Moreover, Al2O3 can be used as the inorganic substance.

The present invention also relates to a method for manufacturing such a substrate for mounting a semiconductor device, and the method includes dry or wet alumina powder colliding with the surface and side surface of the thermally conductive gold plate to separate the cores from each other. While polishing, an alumina layer with a thickness of 0.5 μm or less is formed, and then a coating layer of an electrically insulating IR material with a thickness of 2 to 15 μm is formed by a vapor phase method.

Methods for forming thin films of inorganic substances that can be advantageously used in the present invention include PVD methods such as electron beam evaporation and ion blating, and various fncVD methods, such as plasma CVD methods.
D, optical CvD, M○ (Metal-organic)
Examples include CVD.

In addition, the polishing of the metal plate surface with alumina powder and the formation of an alumina layer are carried out by a dry method using a shot blasting machine, etc., and by charging the substrate to be Qo processed into a dispersion liquid of A1□03.
This is carried out by using a wet method (barrel method) that polishes and forms an alumina layer by rotating and using centrifugal force.

The substrate for mounting a semiconductor device of the present invention is characterized in that a thin layer 3 of alumina is provided between a metal plate 1 and an inorganic insulating coating layer 2, for example as shown in FIG. This intervening layer 3 greatly improves the adhesion between the metal plate 1 and the coating layer 2 of the resulting product, resulting in a long-life product that does not deteriorate in adhesion even during the heat cycle test described above. It becomes possible to provide an electrically insulating and heat dissipating substrate.

The thickness of the alumina thin film as the intervening layer must be 0.5 μm or less, preferably in the range of 0.05 to 0.3 μm. If this condition is not met, the thickness of the alumina thin film as the intervening layer must be within the range of 0.05 to 0.3 μm. Adhesion with the layer cannot be ensured. That is, if the thickness exceeds 0.5 μm, especially if it exceeds 1 μm, the film obtained by collision with the alumina powder is fragile and easily peels off, and if the thickness is less than 0.05 μm,
In particular, if the thickness is less than 0.02 μm, the metal plate surface will include areas where no alumina thin film is formed locally.
On the contrary, adhesion deteriorates.

Furthermore, it is important to use alumina for the surface treatment by shot blasting, etc. For example, alumina powder mixed with 10 to 20% MgO or SiO□ or 510%
I also tried shot blasting using only two powders, but
It was confirmed that the adhesion was even lower than that of the conventional one.

On the other hand, the m-type insulating layer can be formed by various PVDSCVD methods, among which it is particularly advantageous to use the ion blating method.

The reason for this is that according to this method, a film can be formed using extremely fine precipitated particles, and therefore an extremely dense layer can be formed.

The thickness of this coating layer needs to be in the range of 2 to 15 μm, preferably 5 to 10 μm, as described above. That is, when the thickness of the coating layer exceeds 15 μm, the film tends to peel off, while when the thickness is less than 2 μm, especially 1 μm.
If it is less than m, the electrical insulation of the substrate cannot be maintained.

In addition, in order to ensure the corrosion resistance of the metal plate, it is also a good idea to plate the entire surface of the metal plate with N1, U, etc. before base treatment, and this will equally inhibit the adhesion between the metal plate and the coating layer. It will not be done.

Formation of this plating layer can be carried out by various known methods, and is not particularly limited. For example, a vapor deposition method, a dipping method, etc. can be mentioned.

In this way, it is possible to provide a substrate for mounting a semiconductor, which is excellent in both electrical insulation and heat dissipation, has high adhesion strength, and has good thermal stress resistance.

In fact, the following examples will further specifically explain the semiconductor device mounting substrate of the present invention and its manufacturing method, and will compare the effects of the substrate of the present invention with the results of reference and comparative examples. prove it.

Examples 1 and 2 A sintered body of a mixture of Cu powder and MO powder [C
u-20% Mo], and alumina powder of 10 to 30 μmφ was applied to the surface of this sintered body using a yacht blasting machine at an air pressure of 3 to 30 μm while continuously feeding the sintered body at a speed of 5 m/min.
Impacting at 5 kg/cI11 for 1-5 minutes polished the surface and formed two samples with alumina layers of 0.1 and 0.2 μm thickness. Next, after cleaning the sintered body with methylene chloride, A I 20 was used as the vapor deposition material.
It was deposited by electron beam heating using s. Vapor deposition was performed at an oxygen pressure of 5 Xl0-'Torr and a high frequency power of 10011
1 (13,56 MHz) was applied to ionize a part of the evaporated substance, the substrate temperature was 200°C to 400°C, and the evaporation rate was 0.1 μm/min.
An alumina coating layer with a thickness of 2 μm was formed.

Reference Examples 1 to 4 The same procedure as in Examples 1 and 2 was carried out. However, reference example 1
and 2, the alumina layer is 0.8 μm and 0.3 μm, respectively.
μm, alumina coating layer 7, 5 and 17.3 μm,
In addition, for Reference Examples 3 and 4, only a mixture of alumina powder and silica and phosphoric acid were used during shot blasting, the base treatment film thickness was 0.3 μm and 0.2 μm, and the alumina coating layer was 8 μm. .5μm, 7.9μm
And so.

Comparative Examples 1 and 2 Substrates were fabricated using the conventional method in the same manner as in Examples 1 and 2, except that the shot blasting using alumina powder was omitted.

For the substrate sample thus produced, a Cu-W round rod (10φ) of the same type as the metal substrate was bonded to the vapor phase film using an Epoquin resin, and an adhesion strength test was conducted by pulling it on a Tensilon test rock. The results are shown in Table xi below.

Table 1 As is clear from the results shown in Table 1, the adhesion strength between the metal plate and the deposited film is approximately twice as strong in the substrate fabricated according to the method of the present invention as in the substrate fabricated by the conventional method. You can understand that there has been a huge improvement, or even more.

In addition, as seen in Reference Example I, when an alumina base treatment film is formed that exceeds the film thickness specified in the present invention in the Nyoyo blasting process, the adhesion strength may be low even if the conditions of the pond are met. Furthermore, it is clear from the results of Reference Example 2 that even if the alumina coating layer is too thick, sufficient adhesion strength cannot be achieved.

Example 3 and Comparative Example 3 According to Examples 1 and 2, the base alumina layer was 0.2 μm thick.
A substrate with an alumina coating layer of 8.6 μm and a conventional substrate in which only the alumina coating layer was formed with the same thickness using the same procedure were prepared. These two samples were subjected to a thermal cycle test consisting of alternating cooling at -65°C and heating at 125°C, and the changes in adhesion strength during the test were tracked. Shown in the figure.

As is clear from the results in Figure 2, the product of the present invention shows almost no change in adhesion strength over the entire test cycle;
With conventional products, adhesion strength decreases by more than 20% after 200 thermal cycles or more.

Effects of the Invention Thus, according to the present invention, since a thin film layer of alumina is interposed between the metal plate and the evaporation film by surface treatment, it has excellent electrical insulation and heat dissipation properties. The adhesion strength between the metal plate and the electrical insulator film has been significantly improved to about twice or more than that of conventional products, providing a long-life board that is virtually unaffected by multiple thermal cycles. be done.

Therefore, the semiconductor mounting substrate of the present invention can be widely used as an integrated circuit package material, a hybrid IC substrate, and a motherboard substrate, and can greatly improve the reliability of semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the semiconductor mounting substrate of the present invention, and FIG. 2 is a graph showing the behavior of the product of the present invention and a conventional product in a listening cycle test. (Main reference numbers) l Metal plate, 21i covering layer, 3 Alumina layer 1'1 Applicant Sumitomo Electric Industries Co., Ltd. Agent
Patent attorney Masahiko Arai 1; Metal plate 2: Covering layer 3: a) X/Mina, 1

Claims (8)

[Claims] (1) A metal plate with good thermal conductivity, an alumina layer with a thickness of 0.5 μm or less provided on the metal plate, and an inorganic insulating material with a thickness of 2 to 15 μm formed on the alumina layer. 1. A substrate for a semiconductor device, comprising a coating layer. (2) The metal plate is copper and its alloy, aluminum and its alloy; cladding of copper and its alloy and aluminum alloy; low thermal expansion coefficient alloy; Mo, W, Cu, Al
, Si powder alloy. (3) The substrate according to claim 1 or 2, wherein the coating layer is formed of an Al_2O_3 material. (4) Claims 1 to 3, characterized in that the thickness of the alumina layer is within a range of 0.05 to 0.3 μm.
The substrate according to any one of Items. (5) The substrate according to any one of claims 1 to 4, wherein the thickness of the coating layer is within a range of 5 to 10 μm. (6) polishing the surface and side surfaces of a metal plate with good thermal conductivity by colliding alumina powder in a dry or wet manner, and at the same time forming an alumina layer with a thickness of 0.5 μm or less on the surface and side surfaces; A metal plate with good thermal conductivity, an alumina layer and an insulating inorganic material, characterized in that a coating layer of an insulating inorganic material is then formed on the alumina layer by a vapor deposition method to a thickness of 2 to 15 μm. A method of manufacturing a substrate for a semiconductor device comprising a coating layer. (7) The method according to claim 6, wherein the vapor phase deposition method is one selected from the group consisting of a physical vapor deposition method and a chemical vapor deposition method. (8) The method according to claim 6 or 7, further comprising the step of plating the metal plate with a corrosion-resistant metal before the alumina powder polishing step.