JPH0740599B2 - High thermal conductive insulating substrate and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high thermal conductive insulating substrate and a method for producing the same.

[Problems to be solved by conventional techniques and inventions]

With the advancement of ICs, LSIs, etc., electronic circuits are becoming smaller, more highly integrated, and more powerful, and the mounting density of semiconductor devices is becoming higher. High integration of such semiconductor devices,
The number of elements per chip is increasing year by year with the increase in output and density, and the amount of heat generated per chip is also increasing. This heating value is also increasing. This increase in calorific value is
Since the reliability of semiconductor devices is greatly affected, there is a strong demand for packaging materials with high thermal conductivity. Moreover, in the hybrid IC, since heat-generating components are housed in the same package, a high thermal conductive insulating substrate is required to further promote high-density mounting.

Further, in consideration of actually mounting the device, it is important that the coefficient of thermal expansion be close to the coefficient of thermal expansion of the device and other package constituent materials and the circuit board.

As a substrate satisfying both of the above, AlN, hitaseram SiC,
Ceramic substrates such as BeO have been considered, but both are expensive and BeO is toxic.
, Which uses BeO as a sintering aid, has a problem that the dielectric constant at high frequency is as large as about 40 at 1MHz, and AlN has a problem that it has poor stability against water or alkali. have.

The present invention is to obtain an insulating substrate having a high thermal conductivity which is close to the thermal expansion coefficient of an element or other package constituent material or a circuit board, and which does not have the drawbacks of ceramic substrates such as AlN, Hitaracem SiC, and BeO. With the goal.

[Means for solving problems]

The present invention has been made by discovering that the above problem can be solved by using a substrate in which a single crystal silicon or polycrystalline silicon substrate surface is coated with an insulating layer having a high thermal conductivity and a low dielectric constant at high frequencies. And a diamond-like carbon or hydrogen atom and a halogen group containing 9 atm% or less of at least one of silicon and germanium atoms, which is an insulating layer having a high thermal conductivity on at least a part of the surface of the monocrystalline silicon or polycrystalline silicon substrate. High thermal conductivity insulating substrate coated with amorphous silicon carbide containing at least one of the elements, and silicon and germanium in which at least a part of the surface of the single crystal silicon or polycrystalline silicon substrate is an insulating layer having high thermal conductivity Diamond-like carbon or hydrogen atoms containing 9 atm% or less of at least one atom When manufacturing a high thermal conductivity insulating substrate coated with amorphous silicon carbide containing at least one of the halogen group elements, set the single crystal silicon or polycrystalline silicon substrate on the RF input electrode side and The present invention relates to a method for producing an insulating substrate having high thermal conductivity, which is characterized in that an insulating layer is formed by a plasma CVD method by applying a magnetic field parallel to the substrate surface by applying DC voltage and RF power.

〔Example〕

The monocrystalline silicon or polycrystalline silicon substrate used in the present invention is composed of monocrystalline silicon or polycrystalline silicon having a thermal conductivity of 50 W / m · K or more, for example, 10 to 200 m.
It is a substrate having an m ^phi or 10 to 200 mm ^□ in such thick 0.1~2mm shape.

In the present invention, at least a part of the surface of the substrate is covered with an insulating layer having a high thermal conductivity.

Covering at least a part of the surface means that at least a necessary part is covered, and there is no particular limitation on the coverage ratio of the substrate surface, and it may be the entire substrate surface, or only a small part. Good.

As a material for forming an insulating layer having a large thermal conductivity, preferably 50 W / m · K or more, more preferably 100 W / m · K or more, for example, diamond, diamond-like carbon, silicon carbide, Crystalline silicon carbide (including those containing fine crystals, the same applies below),
Examples thereof include c-BN, h-BN, and AlN. One or more of these are used to form an insulating layer having a film thickness of preferably 1 to 50 μm, more preferably 2 to 20 μm. When the insulating layer is formed using two or more kinds of materials, it may be a composite insulating layer.

The material forming the insulating layer in the high thermal conductive insulating substrate of the present invention is diamond-like carbon and / or amorphous silicon carbide.

When the material for forming the insulating layer is diamond-like carbon, one containing either one or both of silicon and germanium atoms in the range of 9 atm% or less has a small internal stress, a large adhesive force, and more diamond. It is preferable because it has a physical property close to that of 0.1 to 4 atm%, more preferably 0.1 to 4 atm%. The thermal conductivity decreases when the amount of silicon or germanium in the film exceeds 9 atm%.

Although the details of such effects of trace amounts of Si and Ge are not known at present, it is considered that the sp ³ orbitals of Si and Ge are probably effective for nucleation of diamond.

A patent application has already been filed for a hard carbon film containing trace amounts of Si and Ge.

When the material forming the insulating layer is amorphous silicon carbide, a material containing at least one of hydrogen atom and halogen group element in the range of 30 atm% or less is preferable from the viewpoint of high thermal conductivity, It is more preferable that the content is in the range of 0.1 to 10 atm%.

The insulating layer as described above usually has an electric resistivity of 10 ⁸ (Ω · cm) or more and a withstand voltage of 20 V / μm or more, and is preferably used as an insulating substrate.

Next, a method for manufacturing the high thermal conductive insulating substrate of the present invention will be described.

The method for forming the insulating layer on the surface of the single crystal silicon or polycrystalline silicon substrate is not particularly limited, and any method can be applied as long as the insulating layer made of the above-mentioned materials is formed.

Specific examples of such a method include DC discharge plasma CVD that can be applied when forming an insulating layer made of diamond, diamond-like carbon, silicon carbide, amorphous silicon carbide, hexagonal BN, cubic BN, or the like. Law, R
F discharge plasma CVD method, DC discharge / RF discharge mixed plasma CVD method, and DC discharge / RF discharge mixed plasma CVD method having a magnetic field perpendicular to the electric field can be cited. Especially diamond, diamond-like carbon, silicon carbide,
When forming an insulating layer made of amorphous silicon carbide, applying a plasma CVD method of mixing both DC discharge and RF discharge with a magnetic field orthogonal to the electric field on the substrate resulted in better crystallinity and better thermal conductivity. It is preferable in that the film can be produced at high speed.

As a concrete method for manufacturing a high thermal conductive insulating substrate by the plasma CVD method of mixing DC discharge and RF discharge having a magnetic field orthogonal to the electric field on the substrate, for example, as shown in FIG. A single crystal silicon or polycrystalline silicon substrate (1) is set on the electrode (2) side, and a DC voltage, preferably −, is applied to this electrode through a high frequency choke coil (3).
Apply DC voltage of 150-−600V, RF power, preferably 1
RF power of 00 to 400 W (140 to 560 mW / cm ² ) is applied, a reaction pressure of 0.1 to 20 Torr and a substrate temperature of 200 to 350 ° C., and a magnetic field (B) parallel to the substrate surface, preferably 100 to 100
There is a method of forming an insulating layer while applying a magnetic field (B) of 0 gauss.

The substrate of the present invention thus produced has a thermal conductivity of
50 W / m · K or more, preferably 100 W / m · K or more, surface Vickers hardness of 500 or more, preferably 1500 or more, more preferably 2000 or more, electrical insulating property is 1 × 10 ⁹ Ω, depending on the type of the insulating layer.・ It has characteristics such as a dielectric constant of 20 cm or less at 1 MHz (15 or less for silicon carbide) and a dielectric loss of 0.02 or less at 1 MHz.

Further, the coefficient of thermal expansion uses a single crystal silicon or polycrystalline silicon substrate as a substrate for forming an insulating layer,
It is suitable as a hybrid IC substrate material for thick film circuits that requires high-temperature treatment, and is extremely stable against acids and alkalis.

Hereinafter, the present invention will be described based on examples.

Examples 1 and 2 SiC films were formed on single crystal silicon by a plasma CVD apparatus as shown in FIG.

A 100 × 100 × 0.5 mm silicon substrate (1) was set on the RF charging electrode (2) side as shown in FIG. DC voltage was applied through the high frequency choke coil (3). A magnetic field (B) was applied to the vicinity of the substrate in a direction orthogonal to the electric field, that is, parallel to the surface of the silicon substrate. The magnetic field strength was 100-500 gauss. This equipment heats the substrate temperature to 200-300 ℃,
Discharge of both DC and RF was generated. H ₂ as reaction gas
_{= 100~200SCCM, CH 4 = 20~80SCCM,} SiH 4 = 10~60SCCM
Flow through the gas inlet (4) and RF power 100-300W (140
˜420 mW / cm ² ) was applied and a DC voltage of −150 to 400 V was applied. The reaction chamber pressure was 0.3-5 Torr. With a reaction time of about 1 hour, a silicon carbide film of about 3 to 5 μm was obtained.

As a result of X-ray diffraction analysis, the obtained film was found to contain microcrystalline β-StC. From the IR measurement of the film, there was absorption of hydrogen bonded to silicon and carbon in the film, and the hydrogen content in the film was 1 to 15 atm%.

Table 1 shows various properties of the obtained film. The film thickness is about 5 μm. Table 1 shows that the carbon contents in the film are 40 atm% and 60 atm%, respectively.

The values of various characteristics changed depending on the amount of silicon and the amount of carbon in the film, and the tendency was that when the amount of carbon exceeded 50 atm%, the hardness increased, but the thermal conductivity decreased.

The obtained insulating substrate has a lower dielectric constant than high thermal conductivity SiC obtained by normal sintering, because SiC is not completely crystalline or polycrystalline, but amorphous silicon containing hydrogen. This is considered to be because the structure is composed of both carbide and microcrystalline SiC, and the amorphous part containing hydrogen has a low dielectric constant, and the microcrystalline part improves the thermal conductivity.

Example 3 An insulating substrate was produced in the same manner as in Example 1 by using a normal RF plasma CVD device (device without magnetic field and DC power supply).
The obtained film is amorphous, and when the carbon content is 40 atm%, the various properties of the film are excellent as shown in Table 1, and the thermal conductivity is 50 to 90 W to mK. It was

Reference Example 1 Film formation was carried out using the same apparatus as in Example 1.

Magnetic field strength (B) 300-1000 gauss, substrate temperature 250-350
℃, as a reaction gas H ₂ = 100-300SCCM, CH ₄ = 1-10SCC
RF power was 100 to 400 W (140 to 560 mW / cm ² ), DC voltage was −200 to 600 V, and reaction chamber pressure was 0.1 to 20 Torr.

The experimental conditions were different from Example 1 in that RF power and DC voltage were large, and CH ₄ was diluted with H _{2 to} 10% by volume or less.

With a reaction time of 2 hours, a diamond-like carbon film having a thickness of about 3 to 5 μm was obtained. The surface Vickers hardness of the obtained film is 6000 ~
The value was close to 8,000, which is close to that of natural diamond. Also of the membrane
The generation of diamond particles was confirmed by TED (electron diffraction) analysis. The film produced by the conditions differed considerably. Table 1 shows various characteristics of a 5 μm film prepared by using methane (5% by volume or less) at a relatively low concentration. The adhesion hardness was as small as ²⁰ to 50 kg / cm ² .

Example 4 Under the same conditions as in Reference Example 1, 0.1 to 7% by weight of silane gas or 0.1 to 10% of germanium hydride gas was added to methane gas.
5% by volume was added to produce a diamond-like carbon film.

Table 1 shows various characteristics of the film produced by adding 0.5% by volume of silane gas.

Silicon was present at 1 atm% in the film (determined by ESCA).

The diamond-like carbon film containing a small amount of silicon had a very small internal stress of the film itself, the adhesive force was several times that of the film containing no silicon, and the electrical insulating property was improved.

[Effects of the Invention] Diamond-like carbon or hydrogen atoms containing 9 atm% or less of at least one of silicon and germanium atoms, which is an insulating layer having a high thermal conductivity, on a monocrystalline silicon or polycrystalline silicon substrate, and among halogen group elements, The substrate of the present invention provided with a layer made of an amorphous silicone carbide containing at least one kind has a high thermal conductivity and a low dielectric constant, and thus can be used as a hybrid IC substrate or a substrate for a high frequency high power transistor.

[Brief description of drawings]

FIG. 1 shows a plasma CV used for manufacturing the substrate of the present invention.
It is explanatory drawing regarding a D apparatus. (Main symbols in the drawings) (1) Silicon substrate

Claims (3)

[Claims] 1. At least one of silicon and germanium atoms, which is an insulating layer having a high thermal conductivity, is formed on at least part of the surface of a single crystal silicon or polycrystalline silicon substrate by using 9a.
A highly thermal conductive insulating substrate coated with amorphous silicon carbide containing at least one of diamond-like carbon or hydrogen atoms and a halogen group element containing tm% or less. 2. At least one of silicon and germanium atoms, which is an insulating layer having a high thermal conductivity, is formed on at least a part of the surface of a single crystal silicon or polycrystalline silicon substrate by using 9a.
When manufacturing a high thermal conductivity insulating substrate coated with amorphous silicon carbide containing at least one of diamond-like carbon or hydrogen atoms containing tm% or less and a halogen group element, a single crystal silicon or polycrystalline silicon substrate is used.
Set it on the RF input electrode side, apply DC voltage and RF power to this electrode, and apply a magnetic field parallel to the substrate surface to generate plasma.
A method of manufacturing an insulating substrate having high thermal conductivity, characterized in that an insulating layer is formed by a CVD method. 3. The RF input electrode having an insulating layer on which a single crystal silicon or polycrystalline silicon substrate is set has a D of −150 to −600 V.
C voltage and RF power of 100 to 400 W (140 to 560 mW / cm ² ) are applied, a magnetic field of 100 to 1000 Gauss is applied parallel to the substrate surface, and the reaction pressure is 0.1 to 20 Torr and the substrate temperature is 200 to 350 ° C. The manufacturing method according to claim 2.