JPH11214382A - Low-dielectric-constant insulating material, mounting circuit board, and electric solid device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a low-dielectric-constant material having a dielectric constant not larger than that of a conventional dielectric material and having thermal resistance capable of enduring during the mounting process by compounding a compound, which chemically modified adamantane, and an insulating resin via chemical bonding. SOLUTION: A solution of. e.g. 10 wt.% of, alicyclic polyolefin formed by dissolving alicyclic polyolefin into tetrahydrofuran is reacted with adamantane bromide (C10 H15 Br) and Grignard's reagent CH2 =CHMgBr to synthesize chemically modified adamantane with one introduced vinyl radical, and this chemically modified adamantane is dissolved until the saturated solution thereof is formed. After this saturated solution is spread on a copper substrate and dried, a heat treatment is carried out e.g. at 220 deg.C for 5 minutes, in a nitrogen atmosphere to thermally cure it. Then, the resin is cured by carrying out a heat treatment, e.g. at 200 deg.C for 5 hours, as after-cure to form a low-directric constant insulating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a low dielectric constant insulating material,
The present invention relates to a mounted circuit board and an electric solid-state device, and particularly to a low-dielectric-constant insulating material suitable for high-speed propagation of signals by mounting electronic devices such as semiconductor devices at high density, and mounting using the same. The present invention relates to a circuit board or an electric solid state device.

[0002]

2. Description of the Related Art In recent years, from personal computers to high-performance computers, the speed of semiconductor devices used has been remarkably increased, and the transmission delay caused by the parasitic capacitance in the wiring portion of the mounting circuit board is relatively high. Is becoming more and more important.

As a result, a thin resin wiring suitable for high-density and fine multilayer wiring has been applied as a material of a mounting circuit board for a CPU of a computer.
In order to realize a higher-speed computer in the future, it is indispensable to develop a low dielectric constant insulating material that utilizes high-density and fine multilayer wiring and is suitable for high-speed signal transmission.

[0004] Conventionally, as high-density mounting circuit board materials used for high-speed computers, epoxy resins,
Polyimide resins and the like are used, but recently, olefin-based and fluorine-based materials have been receiving attention as resins having lower dielectric constants.

The relative dielectric constant ε _s of such a condensed resin is expressed by the following Clausius-Mossottti equation in consideration of the local electric field.

(Equation 1) Here, α is the polarizability of the molecules constituting the resin, and
N is the number of molecules per unit volume.

This equation is solved for the relative permittivity ε _s and α
As can be seen from partial differentiation with N, the relative permittivity ε _s decreases as the polarizability α decreases and the number of molecules N per unit volume decreases.

Referring to FIG. 2, FIG. 2 shows the Clausius-Mossotti equation as a relative permittivity ε _s.
This shows the relationship between ε _s and N · α from the equation solved for N.α = 0, that is, ε _s = 1 in a vacuum where there is no molecule, and N · α is large. Ε _s also increases as N · α = 3 / 4π (≒ 0.2
387) becomes infinite.

On the other hand, the polarizability α is expressed as follows, where μ is the dipole moment induced by the electric field E.

(Equation 2)

Therefore, the polarizability α has 3 × 3 = 9 elements. Generally, the average polarizability is defined as follows and used as a scalar quantity.

(Equation 3)

From the above-mentioned relational expression between the electric field and the induced dipole, it can be understood that the polarizability increases as the material generates a large dipole with a small electric field. In other words, electrons that easily move into the dielectric material are generated. The polarizability α increases as it exists.

In order to keep the polarizability α low,
Consideration is being given to the use of olefin-based resins and fluorine-based resins.These resin materials have a large number of saturated bonds and contain fluorine with a high electronegativity. This is because it becomes smaller.

However, the relative dielectric constant ε _s of such a resin material
Is known to be not less than 2 within a range of about 2.2 to 2.8, and these resin materials have a self-fusing property, that is, have a low melting point and form a wiring layer. There are still many problems to be solved, such as poor adhesion to conductive metal to be formed or poor workability of via holes formed between layers.

On the other hand, as is apparent from the above Clausius-Mossotti equation, there is also a method of lowering the relative dielectric constant by reducing the number of molecules N per unit volume. For example, the relative dielectric constant can be reduced by using a foamed material. Although it is possible to lower it, it is obvious that it is not suitable as an interlayer insulating layer for fine wiring of the order of several μm or several tens of μm in terms of withstand voltage and the like.

[0014] Further, in order to reduce the weight of the insulating layer or to reduce the coefficient of thermal expansion, it has been attempted to compound a glass fiber or a carbon fiber with a resin material. Has a problem that the relative dielectric constant of the insulating layer is raised, and when carbon fibers are compounded, there is a problem that the withstand voltage of the insulating layer is reduced.

Further, in the material forming the insulating layer,
In order to reduce the number of molecules N per unit volume by utilizing the space at the molecular level, fulleren, a polyhedral carbon material composed of a five-membered ring and a six-membered ring, is used.
e) and mixing of carbon nanotubes (Carbon nanotube) having a graphite structure in a cylindrical lattice shape with a resin has also been attempted, and will be described with reference to FIG.

FIG. 3 (a) is a diagram showing the molecular structure of C60 comprising ₆₀ carbon atoms 11 which is a typical fullerene, in which all bonds between carbon atoms 11 are single. It has a soccer ball structure that is a truncated icosahedron composed of a six-membered ring and a five-membered ring formed of bonds.

[0017] see FIG. 3 (b) Figure 3 (b) is a sectional view through the central axis of the C _60, carbon atoms 11 in the interior of the truncated icosahedron as apparent from FIG.
Does not exist, and therefore, the density of the electron cloud 12, that is, the existence probability of electrons is significantly reduced inside. Therefore, an attempt is made to reduce the relative dielectric constant by utilizing the internal space having a low existence probability of electrons. Is what you do.

First, 6-methyl-1,4,5,8-dimethyl
Tano-1,2,3,4,4a, 5,8,8a-octahi
Ring opening polymerization of dronaphthalene (MTD) by a known method
And alicyclic polyolefin obtained by hydrogenation
Alicyclic polio prepared by dissolving in drofuran (THF)
C dissolved in THF in a 10% by weight solution of refin
₆₀To make a saturated solution dissolved until
After applying the solution on a copper substrate and drying, 220 ° C
At a temperature of 5 minutes for heat curing.

Then, as an after cure, a resin is cured by performing a heat treatment at a temperature of 200 ° C. for 5 hours in a nitrogen atmosphere having an oxygen concentration of 10 ppm or less to form a 15 μm-thick low dielectric constant insulating film. I do.

A gold electrode having a diameter of 1 mm was vapor-deposited on the insulating film using a mask, and the relative dielectric constant was measured at 1 MHz.
_The dielectric constant of the insulating film containing ₆₀ is 2.8, and
The thermal decomposition onset temperature was 300 ° C.

[0021]

However, such C ₆₀
The relative permittivity of the insulating film containing 2.8 is 2.8, and there is not much improvement in the relative permittivity, and the relative permittivity is still high for use in high-density mounting substrates for future high-speed computers. There is.

[0022] This is because C _60, etc. without dissolving only trace amounts in a solvent with limited from the relationship between the solubility, be mixed with the resin, it is difficult to composite for easy phase separation, thus, as C ₆₀ It is considered that this is because the internal space of the vehicle cannot be sufficiently and effectively used.

Accordingly, an object of the present invention is to provide a low dielectric constant insulating material having a relative dielectric constant equal to or lower than that of a conventional dielectric material and having heat resistance or the like that can withstand a mounting process.

[0024]

Here, means for solving the problems in the present invention will be described with reference to FIG. (1) The present invention is characterized in that, in a low dielectric constant insulating material, a compound obtained by chemically modifying adamantane and an insulating resin are combined through a chemical bond.

FIG. 1 shows an adamantane (C) used in an embodiment of the present invention.
FIG. 3 is a diagram showing the molecular structure of ₁₀ H ₁₆ ), in which all 10 carbon atoms 1 are single-bonded to adjacent carbon atoms 1 or hydrogen atoms 2 to form a bulky structure having a space in the molecule. I have.

Therefore, by adding this adamantane, the number of molecules or atoms per unit volume of the resin can be reduced, whereby the relative dielectric constant of the low dielectric constant insulating material can be reduced. In this case, in order to make full use of the space in the molecule, it is necessary to chemically modify adamantane in order to facilitate complexation of adamantane by chemical bonding.

The adamantane has a diamond structure in which all carbon atoms 1 are a single bond, that is, a saturated bond, and thus has a characteristic of being excellent in heat resistance. Therefore, it can withstand heat treatment temperatures in a mounting process and a film forming process. be able to.

(2) The present invention is characterized in that, in the above (1), the substituent in the chemical modification is a substituent having a double bond between carbon atoms.

Thus, as a substituent in the chemical modification, a substituent having a double bond between carbon atoms, for example,
Vinyl group (CH ₂ = CH-) or an allyl group (CH ₂ =
When CHCH _2- ) or the like is used, the reactivity with an insulating resin such as an alicyclic polyolefin can be improved due to the presence of a highly reactive double bond, thereby reducing the space in the insulating resin. Since the number of molecules can be increased, the number of molecules per unit volume decreases, and the relative dielectric constant decreases.

(3) The present invention is characterized in that, in the above (1), the substituent in the chemical modification is a substituent consisting only of a saturated bond.

As described above, by using a substituent consisting only of a saturated bond, for example, an alkyl group as the substituent in the chemical modification, the molecular structure of adamantane can be further increased, Therefore, the number of easily movable electrons decreases, and the polarizability decreases, so that the relative permittivity decreases.

(4) The present invention is characterized in that, in the above (1), the substituent in the chemical modification is a substituent containing an oxygen atom.

As described above, the compatibility with the insulating resin can be improved by using a substituent containing an oxygen atom, for example, an ester as the substituent in the chemical modification.

(5) The present invention is characterized in that, in the above (1), the substituent in the chemical modification is a substituent containing a fluorine atom in a side chain of a molecular skeleton.

As described above, when a substituent having a high electronegativity fluorine atom in the side chain of the molecular skeleton is used as the substituent in the chemical modification, the relative permittivity of the insulating resin is increased by the action of the fluorine atom. Can be reduced.

(6) The present invention is characterized in that in any one of the above (1) to (5), the insulating resin is an alicyclic polyolefin.

As described above, the alicyclic polyolefin originally having a low relative dielectric constant is preferable as the insulating resin, and the relative dielectric constant can be further reduced by complexing adamantane.

(7) The present invention is characterized in that in any one of the above (1) to (5), the insulating resin is a photosensitive polyimide.

As described above, by using a photosensitive polyimide having excellent heat resistance and photosensitivity as the insulating resin, the thermal conditions in the mounting process of the electronic component can be relaxed. The photo-curing process can be adopted, and the degree of freedom of the process is increased.

(8) The present invention is characterized in that in any one of the above (1) to (5), the insulating resin is a silicone resin.

As described above, as the insulating resin, a silicone resin which is originally excellent in heat resistance may be used, whereby the thermal conditions in the mounting process of the electronic component can be eased.

(9) Further, according to the present invention, in the mounted circuit board, the low dielectric constant insulating material according to any one of the above (1) to (8) is used as an insulating support member constituting the mounted circuit board. Features.

As described above, the parasitic capacitance between the multilayer wiring layers provided on the mounted circuit board is reduced by using the low dielectric constant insulating material obtained by compounding the chemically modified adamantane as the insulating support member constituting the mounted circuit board. Therefore, a high-speed operation of a mounted CPU or the like is possible, and such a low dielectric constant insulating material is also excellent in heat resistance. Device mounting becomes easier.

(10) The present invention is also characterized in that in the electric solid-state device, the low dielectric constant insulating material according to any one of the above (1) to (8) is used as an interlayer insulating film.

As described above, a low dielectric constant insulating material in which chemically modified adamantane is compounded is used in an electric solid device, for example,
The use as an interlayer insulating film of a semiconductor integrated circuit device can reduce the parasitic capacitance between multilayer wiring layers and the like, so that the operation speed of the semiconductor integrated circuit device can be increased, and such a low dielectric constant insulating material can be used. Is also excellent in heat resistance, so that thermal conditions in a conductive material film forming process and the like can be relaxed.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, a first embodiment of the present invention will be described. First, 6-methyl-1,4,5,8-dimetano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene (MTD) is subjected to ring-opening polymerization by a known method, Adamantane bromide (C ₁₀ ) is added to a 10% by weight solution of an alicyclic polyolefin prepared by dissolving the alicyclic polyolefin obtained by addition in tetrahydrofuran (THF).
H ₁₅ Br) and the Grignard reagent CH ₂ ＣＨCHMgBr were reacted to prepare a saturated solution in which one vinyl group was introduced and chemically modified adamantane was dissolved until it was saturated, and the saturated solution was placed on a copper substrate. And dried, then heat-treated at a temperature of 220 ° C. for 5 minutes to be thermally cured.

Next, as an after cure, the resin is cured by performing a heat treatment at a temperature of 200 ° C. for 5 hours in a nitrogen atmosphere having an oxygen concentration of 10 ppm or less, and finally a 15 μm-thick low dielectric constant insulating material is formed. Form a film.

A gold electrode having a diameter of 1 mm was mask-deposited on the insulating film, and the relative dielectric constant was measured at 1 MHz. As a result, the relative dielectric constant of the insulating film obtained by compounding adamantane chemically modified by introducing one vinyl group was introduced. The rate was 2.3, and the thermal decomposition onset temperature was 320 ° C.

As described above, in the first embodiment of the present invention, adamantane having a bulky molecular structure is converted to 6-methyl-1,4,5,8-dimethano-1,2,3,4,4.
a, 5,8,8a-octahydronaphthalene (MTD)
Is subjected to ring-opening polymerization by a known method and is complexed with an alicyclic polyolefin obtained by hydrogenation, so that the number of molecules N per unit volume in the insulating film is reduced, and the ratio having a correlation with the number of molecules N is reduced. dielectric constant ε _s is reduced.

Since a vinyl group having a carbon double bond is used as a substituent for chemical modification,
The highly reactive double bond facilitates complexation with the alicyclic polyolefin described above and increases the saturation amount of adamantane.
The effect of the reduction is increased.

Further, since adamantane itself has a diamond structure composed entirely of saturated bonds, bonds between atoms are strong, and therefore, the thermal decomposition onset temperature of the insulating film in which adamantane is composited, that is, heat resistance The performance is improved.

Next, a second embodiment of the present invention will be described. First, 6-methyl-1,4,5,8-dimethano-
Ring-opening polymerization of 1,2,3,4,4a, 5,8,8a-octahydronaphthalene (MTD) by a known method, and dissolution of an alicyclic polyolefin obtained by hydrogenation in tetrahydrofuran (THF). Adamantane bromide (C ₁₀ H ₁₄ Br) was added to a 10% by weight solution of the alicyclic polyolefin prepared above.
₂ ) reacting the Grignard reagent CH ₂ ＣＨCHMgBr to introduce two vinyl groups synthesized to form a saturated solution in which the chemically modified adamantane is dissolved until saturated;
After applying this saturated solution on a copper substrate and drying,
A heat treatment is performed at a temperature of 220 ° C. for 5 minutes to thermally cure.

[0053] Thus, in order to chemically modify the vinyl group and two introduced, instead of C ₁₀ H ₁₅ Br in the above first embodiment as bromide adamantane, C ₁₀
H ₁₄ Br ₂ may be used.

Then, as an after cure, the resin is cured by performing a heat treatment at a temperature of 200 ° C. for 5 hours in a nitrogen atmosphere having an oxygen concentration of 10 ppm or less, and finally a 15 μm-thick low dielectric constant insulating material is formed. Form a film.

A gold electrode having a diameter of 1 mm was mask-deposited on the insulating film, and the relative dielectric constant was measured at 1 MHz. As a result, the relative dielectric constant of the insulating film obtained by compounding adamantane chemically modified by introducing one vinyl group was introduced. The rate was 2.2, and the thermal decomposition onset temperature was 330 ° C.

As described above, also in the second embodiment of the present invention, since adamantane having a bulky molecular structure is compounded with an alicyclic polyolefin, the number N of molecules per unit volume in the insulating film is reduced. , The relative dielectric constant ε _s correlated with the number of molecules N decreases.

Further, since a vinyl group having a carbon atom double bond is introduced as two substituents for chemical modification, the saturation amount of adamantane is increased, and the number of molecules per unit volume in the insulating film is increased. As the effect of reducing N increases, the thermal decomposition start temperature of the insulating film increases.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above embodiments. For example, the substituent used for chemical modification is limited to a vinyl group. However, an allyl group having a double bond of a carbon atom as well as a vinyl group may be used.

The substituents used for chemical modification include:
A substituent having only a saturated bond such as an alkyl group may be used, and the molecular structure of adamantane can be further increased by using such an alkyl group for chemical modification, Is a substituent having only a small number of saturated bonds, the polarizability α can be reduced, and the relative permittivity ε _s
Can be reduced.

The substituents used for the chemical modification include:
Oxygen-containing substituents such as silicone-based functional groups and esters may be used.In this case, compatibility with the insulating resin can be increased, and further, as other substituents used for chemical modification, A substituent containing a fluorine atom may be used in the side chain of the molecular skeleton. In this case, since a part of the conjugated system can be made into a saturated bond by fluorine, the relative dielectric constant ε _{s of the} insulating film Can be reduced.

In the description of each of the above embodiments, 6-methyl-1,
4,5,8-Dimethano-1,2,3,4,4a, 5
An alicyclic polyolefin obtained by ring-opening polymerization of 8,8a-octahydronaphthalene (MTD) by a known method and hydrogenating the same is used, but is not limited thereto.
6-methyl-1,4,5,8-dimetano-1,2,3
Instead of 4,4a, 5,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-dimethano-1,
4,4a, 5,6,7,8,8a-octahydronaphthalene, 1,4: 5,10: 6,9-trimethano-1,
2,3,4,4a, 5,5a, 6,9,9a, 10,1
Oa-dodecahydro-2,3-cyclopentadienoanthracene, 1,4-methano-1,4,4a, 4b, 5
8,8a, 9a-octahydrofluorene, 5,8-methano-1,2,3,4,4a, 5,8,8a-octahydro-2,3-cyclopentadienonaphthalene or the like may be used. It is.

The insulating resin used as the base is not limited to alicyclic polyolefin, but may be a polyimide resin or silicone resin having excellent heat resistance. The heat resistance of the formed insulating film is further improved, the thermal conditions in the process of assembling the electronic component are relaxed, and the reliability of the product is increased.

In particular, when a photosensitive polyimide resin is used as the polyimide resin, a photocuring process can be introduced when forming a multilayer wiring structure, and the degree of freedom of the process is increased.

In the description of each of the above embodiments, a single-layer process of manufacturing a low-dielectric-constant insulating material film is described for the sake of simplicity. It is suitable to be used as an insulating support member of a multilayer wiring structure mounted circuit board, thereby reducing the parasitic capacitance between the multilayer wiring layers. Speed delay can be prevented.

The low dielectric constant insulating material film can also be used as an interlayer insulating film of a semiconductor integrated circuit device, and can reduce the parasitic capacitance between the multilayer wiring layers and the conductive film. Heat treatment conditions in the film formation step can be relaxed.

[0066]

According to the present invention, since adamantane having a space in a molecule and comprising a saturated bond is compounded in the insulating resin, the number of molecules per unit volume of the insulating film can be reduced. The polarizability can also be reduced,
As a result, the parasitic capacitance of the mounted circuit board and the like can be reduced, so that the operation speed of the electronic components and the like can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing a molecular structure of adamantane used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the dependence of the relative permittivity of a dielectric material on the number of molecules and polarizability.

3 is a diagram showing a molecular structure of C ₆₀ fullerene.

[Explanation of symbols]

 1 carbon atom 2 hydrogen atom 11 carbon atom 12 electron cloud

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 3/46 H05K 3/46 T (72) Inventor Hiroyuki Sato 4-1-1 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Stock Inside the company (72) Inventor Takao Yokouchi 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Shunichi Fukuyama 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Inside (72) Inventor Yoshihiro Nakata 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (10)

[Claims] 1. A low dielectric constant insulating material comprising a compound obtained by chemically modifying adamantane and an insulating resin through a chemical bond. 2. The low dielectric constant insulating material according to claim 1, wherein the substituent in the chemical modification is a substituent having a double bond between carbon atoms. 3. The method according to claim 1, wherein the substituent in the chemical modification is a substituent consisting only of a saturated bond.
A low dielectric constant insulating material as described. 4. The low dielectric constant insulating material according to claim 1, wherein the substituent in the chemical modification is a substituent containing an oxygen atom. 5. The low dielectric constant insulating material according to claim 1, wherein the substituent in the chemical modification is a substituent containing a fluorine atom in a side chain of a molecular skeleton. 6. The method according to claim 1, wherein the insulating resin is an alicyclic polyolefin.
Item 7. The low dielectric constant insulating material according to item 1. 7. The low dielectric constant insulating material according to claim 1, wherein said insulating resin is a photosensitive polyimide. 8. The low dielectric constant insulating material according to claim 1, wherein the insulating resin is a silicone resin. 9. A mounted circuit board, wherein the low dielectric constant insulating material according to claim 1 is used as an insulating support member constituting the mounted circuit board. 10. An electric solid-state device using the low dielectric constant insulating material according to claim 1 as an interlayer insulating film.