JPH0292532A - Laminate and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a heat sink material of high thermal conductivity where insulator possess high-insulation properties and is superior in thermal conductivity, by forming a high-electrically-conductive metallic layer on at least a part of a one side surface of a diamond layer. CONSTITUTION:A high-electrically-conductive metallic layer is formed on at least a part of the surface which is at least one side surface of a diamond layer. The diamond layer possesses such excellent characteristics that it is superior in thermal conductivity and possesses an appropriate dielectric constant and moreover high-insulation properties. Therefore, when the same is used, for example, for a heat sink material, high thermal conduction is realized and when the same is used for a circuit board for microwaves, it does not happen that resonance is generated in a microwave sphere. A metal which can keep stably high conductivity, for example, aluminum, copper silver, gold, platinum, tungsten and silicone or an alloy or composite of these can be mentioned as a high-conductive metal forming a high-conductive metallic layer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laminate and a method for manufacturing the same, and more specifically, for example, a heat sink material with high thermal conductivity, a microwave circuit board, a capacitor, a CL composite component, etc. Various electronic materials including.

a, which can be suitably used in fields such as electronic devices, etc.
This article relates to a carcass and its manufacturing method.

[Prior art and problems to be solved by the invention] Conventionally, multilayer wiring boards such as heat sink materials and microwave circuit boards have been developed using a laminate in which ceramics such as aluminum oxide and aluminum nitride are sandwiched between two aluminum films. It has been known.

The above types of laminates used in electronic materials such as multilayer wiring boards usually require high insulation properties for the intermediate layer insulators, and often have high thermal conductivity, appropriate dielectric constant, etc. The most demanding characteristics required.

However, these conventional laminates still have problems such as insufficient heat conduction, especially when used as a heat sink material.

Further, when used as a microwave circuit board, there are problems such as the board forming a capacitor due to the dielectric constant, etc., and causing resonance in the microwave region.

In addition, in the field of electronic materials such as heat sink materials and microwave circuit boards, as well as a wide range of multilayer wiring boards, there is a strong need to develop laminates with superior performance to replace the conventional laminates mentioned above. It was wanted.

The present invention has been made in view of the above circumstances.

An object of the present invention is to solve the above-mentioned problems, to obtain a heat sink material in which the intermediate layer insulator has high insulation properties, has excellent thermal conductivity, and has an appropriate dielectric constant. It is an object of the present invention to provide a laminate having excellent properties such as the ability to obtain an excellent microwave circuit board, and a practically advantageous manufacturing method thereof.

[Means for Solving the Problems] As a result of extensive studies by the present inventors in order to solve the above problems, it was found that at least one surface of the diamond layer,
A laminate having a structure in which a highly conductive metal layer is formed on at least a part of its surface has a diamond layer that has superior thermal conductivity compared to conventional ceramics and has an appropriate dielectric constant,
Moreover, it has excellent properties such as high insulation properties, so if used in heat sink materials, it will achieve high thermal conductivity, and if used in microwave circuit boards, it will not cause resonance in the microwave region. Heading 1
We have arrived at the present invention.

That is, the structure of the invention according to claim 1 for solving the above problem is characterized in that a carcass is provided with a highly conductive metal layer on at least a part of at least one surface of the diamond layer. , the configuration of the invention according to claim 2 is,
2. The method of manufacturing a laminate according to claim 1, further comprising forming a diamond layer on a surface of a highly conductive metal substrate, and further forming a highly conductive metal layer on at least a portion of the surface of the diamond layer.

The configuration of the invention according to claim 3 is that a diamond layer is formed on a substrate, the substrate is removed from the obtained diamond layer with the substrate, and then, at least one surface of the diamond layer from which the substrate has been removed is A method for producing a laminate according to claim 1, characterized in that a highly conductive metal layer is formed on at least a portion of the laminate, and the structure of the invention according to claim 4 is characterized in that after forming a diamond layer on the substrate, , forming a highly conductive metal layer on at least a portion of the surface of the diamond layer, then removing the substrate, and forming a highly conductive metal layer on at least a portion of the exposed surface of the removed diamond layer of the substrate. The method for producing an at layer carcass according to claim 1, characterized in that:

Here, the high conductivity metal forming the high conductivity metal layer is not particularly limited as long as it can maintain high conductivity stably, and may be a single metal, an alloy, a composite metal, a metal composition, etc. Either can be used, but typically
For example, suitable examples include aluminum, copper, silver, gold, platinum, tungsten, silicon, and alloys or composites thereof.

Among these, aluminum, copper, *1
Gold, platinum, and doped silicon.

Note that when a plurality of the high conductivity metal layers are provided on one or both sides of the diamond layer, each of the high conductivity metal layers has a single layer structure made of one or more metals. It may have a multilayer structure or a laminated structure of two or more layers,
Moreover, each of the high-conductivity metal layers may be formed of the same type of metal, or may be formed of mutually different types of metal.

There are no particular restrictions on the thickness, shape, or properties of the high conductive metal layer, and it may be in the form of a plate such as a substrate, sheet, or film that is relatively thick and has sufficient mechanical strength, or a coating method.

Thin or thick synthetic films that are relatively thin and do not exhibit sufficient mechanical strength by themselves, such as thin or thick synthetic films that can be obtained as deposits by the plating method and vapor deposition methods such as the PVD and CVD methods. , various types can be exemplified.

For example, if a silicon wafer is used as the highly conductive metal layer, the diamond layer may be formed on the silicon wafer, and the highly conductive metal layer may be formed on at least a portion of the diamond layer by CVD. Therefore, it is possible to manufacture a laminate having a function or action as a heat sink in an element through the manufacturing process of IC or LSI.

Further, when the high conductivity metal layers are provided on both sides of the diamond layer, the two high conductivity metal layers may be adjusted to have the same or similar thickness, or,
Is it possible to adjust the thickness to be different? Generally, it is desirable to appropriately select the thickness, shape, properties, etc., depending on the purpose of use, manufacturing or processing requirements, etc.

For example, one of the two highly conductive metal layers,
A high-conductivity metal layer in the form of a relatively large substrate (hereinafter sometimes referred to as a high-conductivity metal layer or a high-conductivity metal layer substrate) has a relatively large thickness, and the other layer is in the form of a relatively small substrate. A highly conductive metal layer (hereinafter sometimes referred to as a synthetic film-based high conductive metal layer) has sufficient mechanical strength and thermal conductivity even without the use of a separate substrate. It is possible to form a laminate having advantages such as being able to maintain a sufficiently high value and making operations in manufacturing or processing easier.

Here, the suitable thickness of the above-mentioned plate-shaped high-conductivity metal layer may be partly determined depending on other conditions such as the type of metal used, or, for example, the above-mentioned plate-shaped high-conductivity metal layer may be When an aluminum plate or the like is used as the layer, it is preferable that its thickness is usually within a range of about 0.1 to 1 mm.

If this thickness is less than 0.1 mm, sufficient mechanical strength may not be obtained, and if it exceeds 1 mm, for example, the laminate of the present invention may not be used for circuit boards such as heat sink chips. Thermal conductivity may decrease in some cases.

On the other hand, the film thickness of the high conductive metal layer of the synthetic film system is as follows:
Usually, it is within the range of 1 to 1100 JL, preferably 2 to 50 μLm, and in particular, when the laminate of the present invention is used as a circuit board such as a heat sink chip, 5
It is preferable to set it within a range of about 500 JLm.

If this film thickness is too thin, it may not be possible to obtain a film that effectively covers the entire predetermined surface in the manufacturing method described below, and desired characteristics may not be obtained. On the other hand, if it is too thick, the heat conduction efficiency decreases, and for example, when used as a heat sink material, the heat dissipation efficiency may decrease, and the strength when subjected to a temperature cycle test will not be sufficient. However, S.O.
If D p,mft is exceeded, the strength is expected to improve, but the thermal conductivity is low, so it is not practical.

As a method for synthesizing the highly conductive metal layer of the synthetic film system, various methods such as known methods can be used. Specifically, for example, ordinary vacuum evaporation method, direct current, alternating current, high frequency, Plasma discharge method using microwave etc., thermal filament method, thermal CVD method, PVD method, HCD (Holl
Examples include the Cathode Dischargs method and the MOCVD method using organic metals.

In addition, the metal source materials for the highly conductive metal layer of the synthetic film system are as follows:
Metals such as aluminum, copper, silver, gold, platinum, tungsten, silicon, or other metals with high conductivity or alloys can be used, and CVD
In the method, compounds of these metals, for example, halides such as copper chloride, etc. can also be used.

The properties of the diamond layer in the laminate of the present invention cannot be specified in part, or an example of the properties of the diamond layer is that it is a dense aggregate of diamond microcrystals or diamond-like carbon particles. It can be described as.

The average particle size of the diamond microcrystals or diamond-like carbon particles is usually about 0.1 to 30 m, preferably 0.1 to 10 #Lm.

Since the diamond layer is a dense aggregate of diamond microcrystals or diamond-like carbon microparticles having such a particle size, it is possible to make the diamond layer thin.

The thickness of the diamond layer, which is a dense aggregate of diamond microcrystals or diamond-like carbon microparticles having such a particle size, is normal.

0.2-50JLm, preferably 0.2-30JLIT
It is 1.

If this film thickness is too thin, it will not be possible to form a layer that effectively covers the entire surface of a predetermined surface in the manufacturing method described below, and the effect of improving thermal conductivity will be reduced or the desired characteristics may not be obtained. On the other hand, if it is too thick, peeling may occur easily.

As a method for obtaining the diamond layer, for example, there is a method in which an excited gas obtained by exciting a gas containing a carbon source gas is brought into contact with the predetermined base material (highly conductive metal layer or substrate).

In the method, the carbon source gas includes, for example, alkanes such as methane, ethane, propane, butane, pentane, and hexane, alkenes such as ethylene, propylene, butene, pentene, and butadiene, alkyls such as acetylene, benzene, Aromatic hydrocarbons such as toluene, xylene, indene, naphthalene, and phenanthrene, cycloparaffins such as cyclopropane and cyclohexane, hydrocarbons such as cycloolefins such as cyclopentene and cyclohexene, and halides of the various compounds mentioned above. Mention may be made of gas or steam.

In addition, as a carbon source gas, carbon oxide, carbon dioxide, alcohol such as methyl alcohol, ethylene alcohol, etc.
Oxygen-containing carbon compounds such as ketones such as acetone and methyl ethyl ketone, nitrogen-containing carbon compounds such as methylamine, ethylamine, and aniline, etc. can also be used.

Furthermore, although it is not a simple gas, - mixed gas of carbon oxide and hydrogen, synthetic gas, mixed gas containing carbon monoxide and hydrogen such as water gas, gasoline, etc. Class 4 dangerous substances of the Fire Service Act,
Class 1 petroleums, Class 2 petroleum oils such as kerosene, turpentine oil, camphor oil, and pine oil, Class 3 petroleum oils such as heavy oil, and Class 4 petroleum oils such as gear oil and cylinder oil can also be effectively used. Moreover, the various carbon compounds mentioned above can be used in combination.

Among the carbon source gases, for example, methane, carbon oxide, carbon dioxide, or a mixed gas thereof can be preferably used, and a mixed gas of these and hydrogen gas is particularly preferably used. There are many things, especially -
A mixed gas of carbon oxide and hydrogen gas is preferred.

Note that when a mixed gas of -carbon oxide and hydrogen gas is used, the growth rate of the diamond thin film is particularly high. In addition, the adhesion of the diamond thin film is usually particularly good.

It is assumed that the reason why this adhesion is improved is that, for example, the particle size of diamond or diamond-like carbon microcrystals or microparticles becomes smaller.

The above-mentioned carbon oxide and carbon dioxide, or a mixed gas of these and hydrogen gas, is a synthesis gas generator gas or water gas obtained by thermally reacting a carbon source such as coal or coke with air and/or water. It comes from commercially available carbon monoxide gas, carbon dioxide gas, hydrogen gas, cracked gas obtained by decomposing methanol, steam reformed gas of hydrocarbons such as petroleum, etc.

As mentioned above, when using the carbon source gas in combination with hydrogen gas, favorable results may be brought about.The reason for this is that when hydrogen gas excites the carbon source gas, This is presumed to be because the excited carbon in the excited gas obtained by excitation has the effect of removing carbon in the graphite structure and the effect of maintaining the sp 2 structure of carbon atoms in the precipitated diamond crystal even at high temperatures.

Therefore, it is necessary to be careful about the amount of hydrogen gas used, but if the carbon source gas is carbon monoxide gas, usually
The amount of hydrogen gas used is -20 to 9 for carbon oxide gas.
It is 9.9 mol%, preferably 50 to 99.9 mol%.

In addition, the concentration of fermentation carbon is usually 80 to 0.1%.
degree is suitable.

In the above method, the means for obtaining a mixed gas containing carbon in an excited state obtained by exciting the carbon source gas includes:
For example, CVD method, plasma CVD method using radiation such as DC power, AC power, high frequency microwave, etc., ion brating method such as sputtering method, ionization vapor deposition method, ion beam evaporation method, thermal filament method, chemical transport method, etc. You can use this method. Preferred is a plasma CVD method such as a microwave plasma CVD method.

In the above method, an inert gas can also be used as a carrier for the carbon source gas.

Specific examples of the inert gas include argon gas, neon gas, helium gas, xenon gas, and nitrogen gas.

These carrier gases may be used alone or in combination of two or more types.Among the carrier gases mentioned above, argon gas is preferred.

In the above method, the reaction proceeds under the following conditions to form a diamond layer on the substrate.

That is, the temperature of the surface of the predetermined base material varies depending on the excitation means for the carbon source gas.

Although it cannot be determined generally, for example, plasma C
When using the VD method, the temperature is usually room temperature to 1.100°C,
Preferably it is 600°C to 1.000°C.

If the temperature is low, the deposition rate of the diamond layer may be slow or no excited carbon may be produced. On the other hand, if it is too high, it may be difficult to generate diamond or diamond-like carbon, or the diamond layer deposited on the substrate may be etched away, resulting in no improvement in the deposition rate.

The reaction pressure is usually 10-'-10" torr, preferably 10-' to 10' torr. If the reaction pressure is lower than 10-' torr, the deposition rate of the diamond layer may be slow or the diamond layer may On the other hand, even if it is higher than lo'torr, no corresponding effect can be obtained.

In the second aspect of the invention, it is preferable that at least the surface of the plate-shaped highly conductive metal layer on which the diamond layer is to be formed be pretreated, such as by cleaning in advance.

This pretreatment includes, for example, dispersing diamond powder with a particle size of 1 gm or less in an organic solvent such as acetone.
Usually, a method of ultrasonic cleaning for several minutes to several tens of minutes can be suitably used.

At that time, the usage ratio of the above diamond powder is as follows:
For example, usually 1.0 per 10 cc of solvent used.
It is sufficient if it is about 100 g.

In the invention according to claims 3 and 4, the substrate on which the diamond layer is synthesized has at least the above-mentioned diamond, which maintains sufficient stability under the layer synthesis conditions, and which can be easily removed from the synthesized diamond layer. Use a material that can be removed.

Examples of such materials include silicon, heat-resistant glass substrates, insulating substrates such as ceramic substrates, and metal substrates.

Methods for removing the substrate from the synthesized diamond layer include, for example, chemical dissolution and removal methods using acids such as hydrofluoric acid and hydrochloric acid, alkalis, and physical removal methods such as plasma etching and sputtering. I can list the following.

An example of the 8IN body of the present invention will be explained with reference to the drawings.

1 to 3 are cross-sectional views each schematically showing an example of the laminate of the present invention.

In FIGS. 1 to 3, 1 and 1' represent highly conductive metal layers, and 2 represents a diamond layer.

In the laminate shown in FIG. 1, a diamond layer 2 has a highly conductive metal layer l on one side.

In a laminate having such a structure, for example, a highly conductive metal layer made of doped silicon
Those having this can be particularly suitably used as electronic devices and electronic materials.

Furthermore, in the stacked body shown in FIG. 2, the diamond layer 2
has a high conductive metal layer 1 on more than a part of one surface, has a high conductive metal layer 1' on more than a part of the other surface, and has a third
The laminate shown in the figure has a structure in which a diamond layer 2 is sandwiched between a high conductive metal layer l and a high conductive metal layer 1'.

In a laminate having such a structure, for example, the high conductive metal layer 1 is a plate-shaped high conductive metal layer, especially a copper plate, and the high conductive metal layer 1' is a high conductive metal layer of the above thickness. A conductive metal layer, especially a copper film or the like, can be particularly suitably used as a heat sink chip or the like.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention.

(Examples 1 to 4) Carbon monoxide (20% by volume) and hydrogen (80% by volume) were used as raw materials for the diamond film on a copper substrate (10 mm square) with the thickness shown in Table 1 as one of the highly conductive metal layers. %) using a mixed gas with a total gas flow rate of 11003 CC and a substrate temperature of 850 °C.
A diamond layer having the thickness shown in Table 1 was synthesized by the microwave plasma CVD method (2.45 GIIz) under the conditions of .degree. C., pressure of 5 Otorr, and power of 350 W.

The copper plate used above had been pretreated by ultrasonic cleaning for 10 minutes in a solvent in which 0.2 g of diamond powder of 1 μm or less was dispersed in 20 cc of acetone.

Next, on the diamond layer obtained above, using copper as a raw material, HCD (Hollow Cathod) was applied under the following conditions.
A copper film having a thickness of 30#Lm was synthesized by the eDischarge method to obtain a laminate having the structure schematically shown in FIG.

JLL external plasma source gas: argon electron beam: 20V, 200A bias: -100V/cm pressure
: I X 10-'torrSubstrate temperature: 300°C For each of the obtained laminates, the temperature as shown in FIG.
Thermal conductivity was measured in the directions [■ and ■]. The results are shown in Table 1.

Furthermore, reliability tests were conducted on the laminates obtained in Examples 1 to 4 for the items shown in Table 2, and very good results shown in Table 2 were obtained.

(Comparative Examples 1 to 4) Examples 1 to 4 except that aluminum oxide or aluminum nitride shown in Table 1 was synthesized by a reactive sputtering method and used instead of the diamond layer as the insulating layer.
I did it in the same way. Result *l: Copper is 392'll/■
・K *2: Diamond Table 1 is shown in Table 1.

Table [Effects of the Invention] According to the invention of claim 1 of the present application, since a diamond layer having high insulation properties and excellent thermal conductivity is used as an insulator, aluminum oxide or aluminum nitride is used as an insulator. Compared to conventional laminates of this type, which use materials such as It is possible to provide a practically extremely advantageous laminate that can be suitably used as a microwave circuit board, etc., and has excellent characteristics such as not causing any damage.

Further, according to the invention of claim 2 of the present application, a diamond layer is formed on the surface of the high conductive metal layer, and the other high conductive metal layer is further laminated on at least a part of the diamond layer, so a separate substrate is particularly required. The laminate, which has sufficient mechanical strength and high thermal conductivity without the use of a separate substrate, can be used particularly advantageously among the laminates of claim 1 of the present application. Easy and efficient without using
It is possible to provide a method for manufacturing a laminate according to claim 1 which is particularly excellent in practical use.

According to each of the inventions of Claims 3 and 4 of the present application, in the method of manufacturing the laminate of Claim 1 of the present application, a specific method of synthesizing the diamond layer on the substrate and removing the substrate is used, so that both Claim 1: By using a relatively thin high conductivity metal layer of a synthetic film type as the high conductivity metal layer, a relatively thin laminate can be easily and stably obtained. Another object of the present invention is to provide a method for manufacturing a laminate.

[Brief explanation of drawings]

1 to 3 are cross-sectional views each schematically showing an example of the laminate of the present invention. Figure 1 Figure 2 Figure 3 1.1'... Highly conductive metal layer, 2... Diamond layer. ■ Horizontal thermal conductivity ■ Vertical thermal conductivity

Claims (3)

[Claims] (1) A laminate comprising a highly conductive metal layer on at least a portion of at least one surface of a diamond layer. (2) A method for manufacturing a laminate according to claim 1, characterized in that a diamond layer is formed on the surface of a highly conductive metal substrate, and a high conductive metal layer is further formed on at least a portion of the surface of the diamond layer. . (3) forming a diamond layer on the substrate, removing the substrate from the obtained diamond layer with the substrate, and then,
2. The method of manufacturing a laminate according to claim 1, further comprising forming a highly conductive metal layer on at least a portion of at least one surface of the diamond layer from which the substrate has been removed. (4) After forming a diamond layer on a substrate, forming a highly conductive metal layer on at least a portion of the surface of the diamond layer, and then removing the substrate, and removing the exposed surface of the diamond layer from the substrate. 2. The method of manufacturing a laminate according to claim 1, further comprising forming a highly conductive metal layer on at least a portion of the layer.