JP2006028473A - Organic/inorganic composite, its manufacturing method, and semiconductor device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic/inorganic composite which can form an insulating film having a low dielectric-constant, high mechanical strength and high flatness, to provide its manufacturing method, and to provide a semiconductor device using the composite. <P>SOLUTION: The organic/inorganic composite having a crosslinked structure by metal-oxygen bonding comprises a compound expressed in general formula (1). (In the formula, M is a metal or silicon, X is an -O- bond or an OH group involved in crosslinking, R<SP>1</SP>is an 8-20C atom-containing molecular chain group, R<SP>2</SP>is either one of a methyl, ethyl, propyl or phenyl group, n1 and n2 are each either 0, 1 or 2). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic / inorganic composite, a method for producing the same, and a semiconductor device using the same, and more particularly to an organic / inorganic composite having a low dielectric constant.

With the remarkable progress of electronic devices such as computers, demands for higher speed, lighter weight, and lower power consumption due to miniaturization of semiconductor devices are increasing. In response to these demands, miniaturization and high integration in ULSI (ultra-large scale integrated circuit) have been promoted in recent years, and one of the means for realizing this is high integration by multilayer wiring such as a microprocessor. .
And the biggest problem in this multilayer wiring is improvement of the function of the interlayer insulating film. Interlayer insulation films are required to have high functions such as high insulation, reduction of inter-wiring capacitance, reliable film formation in fine wiring spaces, and surface flattening, and various studies have been made. Dielectric constant is a big issue.

  In addition, with respect to a passivation film formed for the purpose of covering and protecting the surface of a semiconductor device, in addition to functions such as moisture resistance, when a bonding pad is formed on this upper layer, or when rearranged wiring is formed. Since the parasitic capacitance between this film and the lower layer wiring causes a serious decrease in driving speed, a reduction in dielectric constant is demanded.

At present, the insulating material mainly used for the interlayer insulating film, the inter-wiring insulating film, and the passivation film is silicon oxide SiO ₂ , and the relative dielectric constant k is about 4.0. In order to reduce the dielectric constant, new materials such as fluorine-doped silicon oxide (k: about 3.7) and organic polymer materials (k: 2.0 to 2.7) have been studied. In addition, various researches such as silicon polymers have been made in order to reduce the dielectric constant (see Patent Document 1).
However, as the speed and integration increase further, the dielectric constant of these materials is not sufficient, and further reduction of the dielectric constant is a problem.

  Under such circumstances, a gas evaporation method has also been proposed. A silicon ultrafine particle oxide film (SiOx ultrafine particle film) formed by a gas evaporation method is a nanoporous film, and an extremely low dielectric constant of 1.83 has been obtained. However, this nanoporous film is highly hygroscopic, has a large increase in relative dielectric constant under the environment of use, is difficult to handle due to brittleness, has a large number of man-hours in the film formation process, and can be put to practical use. It was not a thing. In addition, there is a problem that the formation is performed at a high temperature, and the underlying wiring of the semiconductor device is deteriorated by heat during film formation.

Furthermore, the above-described film has a structure in which voids are randomly formed, and when used as an interlayer insulating film, the mechanical strength is remarkably low, it is easily damaged, and causes a decrease in reliability of the semiconductor element. It was.
In addition, when used as an interlayer insulating film, a passivation film, etc. of a semiconductor device, temperature change and buffering action against mechanical shock are also important issues, and CMP resistance greatly affects the yield of the entire semiconductor device. It has become.
JP 2002-167438 A

As described above, in the conventional insulating film, the dielectric constant cannot be lowered sufficiently and the dielectric constant should be increased if an attempt is made to provide a physical property value that can be practically used for a semiconductor device such as an interlayer insulating film. Then, there was a problem that sufficient heat resistance or mechanical strength could not be obtained.
In particular, when used as an interlayer insulating film, surface level planarization is often performed using CMP (Chemical Mechanical Polishing) or the like. However, in the CMP process, it is necessary to have strength and toughness that can withstand polishing.
Also, semiconductor devices are not only in the manufacturing process, but especially in devices used for high current applications, even during use, they are susceptible to high-temperature environments or temperature changes, and stress is applied to wiring patterns or semiconductor devices. There is also a problem that the apparatus is likely to deteriorate.
Furthermore, the precursor in the method for producing an insulating film material is characterized by containing an organic solvent, but depending on the characteristics of the organic solvent, when an insulating film is formed by a spin coating method, flatness cannot be obtained. There is a problem that a lower dielectric constant cannot be obtained.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an organic-inorganic composite capable of forming an insulating film having a low dielectric constant, high mechanical strength, and high flatness, and a method for producing the same. Another object is to provide a semiconductor device using the composite.

The present invention has been achieved by the following (1) to (29).
(1) An organic-inorganic composite having a cross-linked structure by a metal-oxygen bond, wherein the organic-inorganic composite has a compound represented by the following general formula (1).

(In the formula, M is a metal or silicon, X is an —O— bond or OH group involved in crosslinking, and R ¹
Is a carbon atom-containing molecular chain group having 8 to 20 carbon atoms, R ² represents any one of methyl, ethyl, propyl, and phenyl groups, and n1 and n2 are either 0, 1, or 2, is there. )

(2) The organic-inorganic composite as described in (1) above, wherein M is silicon.

(3) In the general formula (1), R ¹ is a polymethylene group.
) Organic-inorganic composite described in the above.

(4) The organic-inorganic composite as described in (3) above, wherein the polymethylene group is represented by the following general formula (2).

(In the formula, n represents an integer.)

(5) The organic-inorganic composite according to any one of (1) to (4), wherein the compound is a compound represented by the following general formula (3).

(In the formula, X is an —O— bond or OH group involved in crosslinking, and n1 and n2 are either 0, 1, or 2.)

(6) The organic-inorganic composite as described in (1) or (2) above, wherein R ¹ in the general formula (1) is a hydrocarbon group containing a benzene ring.

(7) The organic-inorganic composite as described in (6) above, wherein the hydrocarbon group is represented by the following general formula (4).

(8) In the said General formula (4), n and m exist in the range of the integer of 1-20, The organic inorganic composite as described in said (7) characterized by the above-mentioned.

(9) In the said General formula (4), n and m are 2, respectively, The organic-inorganic composite as described in said (8) characterized by the above-mentioned.

(10) Any of the above (1), (2), (6), (7), (8) and (9), wherein the compound is a compound represented by the following general formula (5) An organic-inorganic composite according to any one of the above.

(In the formula, X is an —O— bond or OH group involved in crosslinking, and n1 and n2 are either 0, 1, or 2.)

(11) The organic-inorganic composite as described in (1) above, further comprising a compound represented by the following general formula (6).

_{X 4-n3 - M - (} R 3) n3 ··· (6)

(Wherein M is a metal or silicon, X is an —O— bond or OH group involved in cross-linking, and R ³
Is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and n3 is either 1, 2 or 3. )

(12) The content of the compound represented by the general formula (6) is 5 to 20% by mass with respect to the total amount of the compound represented by the general formula (1) and the compound represented by the general formula (6). The organic-inorganic composite as described in (11) above, wherein

(13) A method for producing the organic-inorganic composite according to any one of (1) to (12),
Preparing a precursor comprising a mixture comprising a plurality of crosslinkable silyl groups and an organic-inorganic composite crosslinkable compound having a carbon atom covalently bonded thereto;
Depositing the precursor on a substrate;
And a condensation step of hydrolyzing / condensing the crosslinkable silyl group to form an organic-inorganic composite.

(14) The method for producing an organic-inorganic composite according to (13), wherein the precursor includes a solvent having a boiling point of 100 ° C to 130 ° C.

(15) The production of the organic-inorganic composite according to (13), wherein the condensation step includes a step of adding 0.5 to 1.5 equivalents of water to the crosslinkable silyl group. Method.

(16) The method for producing an organic-inorganic composite according to (15), wherein the condensation step further includes a step of adding a catalyst.

(17) The method for producing an organic-inorganic composite according to (16), wherein the catalyst is a Bronsted acid.

(18) The method for producing an organic-inorganic composite according to any one of (13) to (17), wherein the precursor solution includes at least a compound represented by the following general formula (7).

(In the formula, M is a metal or silicon, R ¹ is a carbon atom-containing molecular chain group having 8 to 20 carbon atoms, R ² represents any group of methyl, ethyl, propyl, or phenyl group, R ⁵ represents any one of Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH and OCOCH ₃ groups, and n1 and n2 are either 0, 1, or 2)

(19) The method for producing an organic-inorganic composite as described in (18) above, wherein R ¹ in the general formula (7) is represented by the following general formula (4).

(20) The method for producing an organic-inorganic composite according to the above (19), wherein the structure of the general formula (4) is a p-form.

R ¹ in (21) above general formula _{(7) - (CH 2)} 8 - preparation method of organic-inorganic composite according to (18), which is a octamethylene represented by.

(22) In the general formula (7), the R ² is a methyl group, method for producing R ⁵ is OCH ₃ or an organic-inorganic composite according to (18), characterized in that representing the OC ₂ H ₅ group .

(23) The method for producing an organic-inorganic composite according to (18), wherein the precursor solution further includes a compound represented by the following general formula (8).

R ⁵ _4-n3 -M- (R ³ ) _n3 (8)

(Wherein M is a metal or silicon, R ³ is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and R ⁵ is Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH or Represents any group of OCOCH ₃ groups, n3 is either 1, 2 or 3)

(24) The content of the compound represented by the general formula (8) is 5 to 20% by mass with respect to the total amount of the compound represented by the general formula (7) and the compound represented by the general formula (8). The method for producing an organic-inorganic composite as described in (23) above, wherein

(25) A semiconductor device using the organic-inorganic composite having a crosslinked structure with a silicon-oxygen bond according to any one of (1) to (12).

(26) comprising a semiconductor substrate or an interlayer insulating film interposed between the first wiring conductor formed on the semiconductor substrate and the second wiring conductor;
The semiconductor device according to (25), wherein the interlayer insulating film is formed of an organic-inorganic composite having a cross-linked structure by the silicon-oxygen bond.

(27) A passivation film is formed on a surface of a semiconductor substrate on which an element is formed, and the passivation film is composed of an organic-inorganic composite having a crosslinked structure by the silicon-oxygen bond. 25) The semiconductor device according to (26).

According to this configuration, when the number of carbon atoms in R ¹ is 8 to 20, when the length of the straight chain portion in the molecule is increased, the pore diameter is increased and the porosity can be increased. Rate organic-inorganic composite can be obtained. Moreover, according to this organic-inorganic composite, it is possible to form a low dielectric constant thin film in which pores are uniformly formed, the skeleton strength is high, and the material is not easily deformed by stress. When the pores are non-uniform, there is a problem that stress strain is likely to occur, and not only is the deformation more likely to occur, but also the occurrence of cracks. In the manufacturing process of a semiconductor device, there are many processes that are susceptible to stress at the time of polishing after film formation, or stress in subsequent processes, CVD, or etching. Also, in the mounting process, a plurality of heat processes such as a resin sealing process or heat during solder reflow are often performed. Furthermore, after it becomes a product, there is stress due to repeated heating and cooling during use.

In such a situation, it has a strength that can withstand the CMP process, and has a sufficiently high porosity and a low dielectric constant.
Furthermore, since it has a high degree of toughness, it can provide a highly reliable structure or structure thin film even in a place where it is susceptible to a temperature change due to a large buffering effect against a mechanical shock even when the temperature changes. Moreover, since it is an organic-inorganic composite having a sufficient crosslinking density, a large dimensional change with respect to an environmental change is not observed, and a change in strength is small.

  The organic-inorganic composite of the present invention contains a compound represented by the following general formula (1).

In the formula, M is a metal or silicon, X is an —O— bond or OH group involved in crosslinking, and R ¹
Is a carbon atom-containing molecular chain group having 8 to 20 carbon atoms, R ² represents any one of methyl, ethyl, propyl, and phenyl groups, and n1 and n2 are either 0, 1, or 2, is there. When R ² is involved in the cross-linking of X, as in R ¹ , when it has a carbon number greater than 20, the heat resistance decreases, the voids are too large, the strength decreases, and the skeleton tends to bend. Non-uniformity occurs, the void distribution is not uniform, and sufficient strength or toughness cannot be obtained. On the other hand, if the number of carbon atoms is less than 8, the molecular straight chain is too short to form a good polyhedral structure. Further, when R ² has a hetero atom, there is a possibility of cleavage by acid or heat, but the hydrocarbon compound is extremely stable because it is not easily attacked by these acid or heat. Examples of the hydrocarbon group include an alkylene chain and an aromatic chain.

  According to such a structure, the dielectric constant can be a value of 3.0 or less, has a strength having CMP resistance, and can perform CMP satisfactorily.

  Desirably, in the organic-inorganic composite, M is silicon. Silicon is effective because it is stable in a strong acid, high temperature and high humidity environment and does not adversely affect the semiconductor device.

The metal-oxygen bond is effective in the case of an aluminum-oxygen bond, a titanium-oxygen bond, a zirconium-oxygen bond, etc. in addition to a silicon oxygen bond, and these are stable even in a strong acid, high temperature and high humidity environment. .
Further, silicon-oxygen bonds are mainly used, and metal-oxygen bonds, phosphorus-oxygen bonds, boron-oxygen bonds, or the like may be used in combination. The atomic ratio between silicon and metal elements is preferably 50 mol% or more when the total metal atoms are 100 mol%.

The organic-inorganic composite of the present invention includes those in which R ¹ in the compound represented by the general formula (1) is a hydrocarbon group.
Since R ¹ is a hydrocarbon group, it is a molecular chain that controls flexibility and film properties, and is unstable when there are no carbon atoms.

One of the organic-inorganic composites of the present invention is preferably ^{one in which} the hydrocarbon group of R ¹ in the general formula (1) is a linking group (hydrocarbon group) represented by the following general formula (2).

In the linking group represented by the general formula (2), n is preferably in the range of 8-20. When R ¹ has a branch, the bond connecting the bridges may be broken. On the other hand, in the above configuration of the present invention, R ¹ is a linear polymethylene chain, so it is stable against various external factors, and the moisture resistance of the produced film is improved by the hydrophobicity of the hydrocarbon chain. Thus, it becomes effective as an insulating film.

  In addition to the stability, the linear polymethylene chain has a slightly bendable structure, so that an appropriate flexibility can be imparted to the film and the toughness is improved. These adjustments can be achieved mainly by adjusting the molecular length of the polymethylene chain. Various bis (hydrolyzable silyl) polymethylenes are known as raw materials for introducing silicon-oxygen bridges at both ends of the polymethylene chain. Manufactured by: Ge1est).

In addition, hydrosilylation reaction is performed on 1,7-octadiene, 1,9-decadiene, 1,13-tetradecadiene and the like, which are unsaturated bonds at both ends, so that R ¹ is octamethylene, decamethylene, Raw materials corresponding to tetradecamethylene can be easily synthesized, and any polymethylene chain having up to 20 carbon atoms can be synthesized.
Further, the carbon number of the polymethylene group is preferably 8 to 20 as described above, and can exhibit satisfactory performance with respect to any of heat resistance, toughness, and water resistance. Particularly those having 8 to 12 carbon atoms are preferred.

In the general formula (1), R ¹ is octamethylene, R ² is a methyl group, and a compound represented by the following general formula (3) is desirable.

  In the formula, X is an —O— bond or OH group involved in crosslinking, and n1 and n2 are either 0, 1, or 2.

Thereby, since it is a structure in which eight methylene groups are linked, further raw materials can be easily obtained.
A structure having Si—O crosslinked structures at both ends of a polymethylene group is extremely stable and useful as a basic crosslinked structure of an insulator. This organic-inorganic composite may be a mixture of a plurality of types of molecules. For example, by mixing and using an organic-inorganic composite with n1 = 1 and an organic-inorganic composite with n2 = 2, it is possible to adjust the crosslinking density and the like. It is possible to adjust the void structure, toughness (flexibility), and the like.
The physical properties can also be adjusted by mixing organic-inorganic composite structures having different organic chain lengths and types of substituents.

  In addition, another organic-inorganic composite of the present invention is preferably a structure in which the hydrocarbon group of R1 in the general formula (1) is represented by the following general formula (4 ').

_{-R'-C 6 H 4 -R "} - (o / m / p) Any Yes (4 ')

In the general formula (4 ′), R ′ and R ″ are polymethylene chains having 1 to 20 carbon atoms.
Be in the range of.
When there is a branch in R ′ and R ″, the bond between the bridges may be broken. Adjustment of the void size can be achieved mainly by adjusting the polymethylene chain molecular length.

  In this case, 1,4-bis (trimethoxysilylethyl) benzene is commercially available as a raw material for introducing silicon-oxygen bridges at both ends of the polymethylene chain (Gerest: Ge1est). In addition, the raw material can be easily synthesized by performing a hydrosilylation reaction on divinylbenzene or the like having unsaturated bonds at both ends.

  As a typical example of the specific compound described above, a compound represented by the following general formula (5) is preferable.

(Wherein X is an —O— bond or OH group involved in crosslinking, and n1 and n2 are either 0, 1, or 2)
Since the starting material of the above compound is divinylbenzene, the raw materials are easily available.

  Furthermore, the organic-inorganic composite of the present invention preferably contains a compound represented by the following general formula (6).

_{X 4-n3 - M - (} R 3) n3 ··· (6)

(Wherein M is a metal or silicon, X is an —O— bond or OH group involved in cross-linking, and R ³
Is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and n3 is either 1, 2 or 3. )

In the organic-inorganic composite of the present invention, if the total number of carbon atoms of the compound represented by the general formula (1) is increased, the crosslinking density is decreased and the space in the molecule is increased. Dielectric constant.
Furthermore, by adding a compound represented by the above general formula (6), the crosslink density is lower than that of the compound represented by the above general formula (1) alone. Since the space is further increased, the porosity is higher and the dielectric constant is lower.
In addition, since the R ³ group of the compound represented by the general formula (6) is hydrophobic and the silanol group at the cross-linking point is hydrophilic, the silanol group is located away from the hydrophobic R ³ group. Since it becomes easy, it is thought that it is easy to form a uniform space.
Moreover, due to the hydrophobicity of the R ³ group, even if the space is open, it is difficult for moisture to enter and the dielectric constant is unlikely to deteriorate.
The organic-inorganic composite of the present invention is mostly composed of the compound represented by the general formula (1), thereby increasing the porosity (lowering the dielectric constant) without extremely reducing the mechanical strength. I can do it.

The content of the compound represented by the general formula (6) is not particularly limited, but is 5 to 5 with respect to the total amount of the compound represented by the general formula (1) and the compound represented by the general formula (6). It is preferably 20% by mass.

  The method for producing an organic-inorganic composite of the present invention comprises a step of preparing a precursor comprising a mixture containing a plurality of crosslinkable silyl groups and an organic-inorganic composite crosslinkable compound having a carbon atom covalently bonded thereto. And a step of forming a film of the precursor on a substrate, and a condensation step of condensing the crosslinkable silyl group to form an organic-inorganic composite.

Here, the organic-inorganic composite of the present invention is not particularly limited as a solvent in the precursor coating solution in the step of forming the precursor on a substrate, but the boiling point thereof is 100 ° C to 130 ° C. It is preferable to use an organic solvent. By using an organic solvent having a boiling point of 100 ° C. to 130 ° C., in the formation of the insulating film by the spin coating method, the optimum hydrolysis and dehydration condensation reactions proceed in the coating liquid, and the spin coating is appropriate. The flatness of the coating film can be obtained by maintaining the viscosity.
If the boiling point of the solvent is 100 ° C. or higher, the generation of radial streaks during coating by spin coating is reliably prevented, and the flatness of the coating film is guaranteed. Moreover, when the boiling point of the solvent of the precursor is 130 ° C. or less, the compatibility of the precursor contained in the coating solution is improved, and a uniform coating film is obtained.
Examples of the organic solvent having a boiling point of 100 ° C. to 130 ° C. include 1-butanol and iso-butanol.

  Crosslinking of Si—O by hydrolysis and subsequent dehydration condensation reaction using a plurality of crosslinkable silyl groups, ie, an organic-inorganic composite crosslinkable compound having a hydrolyzable silyl group and a carbon atom covalently bonded thereto. Form the body. Here, the hydrolyzable silyl group is an alkoxysilyl group in which an alkoxy group such as methoxy, ethoxy, propoxy or phenoxy is directly bonded to a silicon atom, a halogenated silyl group in which a halogen such as chlorine is bonded to a silicon atom, and an acetoxy group And carboxysilyl group. Furthermore, a silanol group or silanolate group hydrolyzed in advance can be used. In this case, hydrolysis is unnecessary, and only the condensation reaction needs to be performed.

  The condensation step preferably includes a step of adding an amount of a catalyst necessary for the crosslinkable silyl group to cause a condensation reaction in an equivalent equivalent system.

In the cross-linking reaction step, the target film can be obtained by heating in an arbitrary temperature range that does not damage the underlying material. Specifically, an arbitrary temperature from room temperature to about 500 ° C. can be mentioned, and it is preferably 300 ° C. or higher for sufficiently removing the solvent and hydrolytic condensation, and when applied to a material using aluminum wiring Is preferably 400 ° C. or lower.
In the case of heating in this step, a known method such as pressure heating with an oven can be used. Moreover, when performing this method, in order to perform a hydrolysis and condensation efficiently, water may be added to a precursor mixed solution beforehand, and you may make it heat under water vapor | steam.

  In order to accelerate the generation of the crosslinked structure, an acid such as hydrochloric acid, sulfuric acid, phosphoric acid or the like may be added as a catalyst in the reaction system in advance. Further, since the cross-linking structure is accelerated by a base, it is possible to use a base catalyst such as ammonia or sodium hydroxide. Preferably, the catalyst is an acid, particularly preferably a Bronsted acid. By using an acid catalyst, an organic-inorganic composite having a uniform skeleton structure can be formed.

The condensation step includes a step of adding 0.5 to 1.5 equivalents of water to the crosslinkable silyl group.
Further, the condensation step includes a step of adding a catalyst. At this time, the catalyst amount may be adjusted and added so that an appropriate amount of water is present in an aqueous solution state.
Here, it is desirable to use an acid as the catalyst. Desirably, the Bronsted acid catalyst is an aqueous solution, and the concentration N (regulation) is in the range of 0.1 ≦ N ≦ 3.
Desirably, the precursor solution contains a compound represented by the following general formula (7).

In the formula, M is a metal or silicon, R ¹ is a molecular chain group containing a carbon atom having 8 to 20 carbon atoms, R ² represents any group of methyl, ethyl, propyl, or phenyl group, R ⁵ Represents a group of Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH or OCOCH ₃ , and n1 and n2 are either 0, 1, or 2.

The M is preferably silicon. Further, R ¹ in the general formula (7) is preferably a hydrocarbon group, and is a hydrocarbon containing a polymethylene group or a benzene ring, which is a substituent represented by the following general formula (4) or the following general formula (2). Groups are more preferred.

N and m in the general formula (4) are preferably in the range of 1 to 20, and n in the general formula (2) is in the range of 8 to 20.
As a specific compound represented by General formula (7), the compound shown by General formula (5 ') and General formula (3') is preferable.

In the formula, R ⁵ represents an OCH ₃ or OC ₂ H ₅ group, and n1 and n2 are either 0, 1, or 2.
Here, the crosslinking step is preferably performed at 100 to 300 ° C., and then, it is desirable to perform aging at a relatively high temperature (for example, 300 to 500 ° C.) in order to completely react the unreacted remaining crosslinkable silyl group. .

  Furthermore, the precursor solution preferably contains a compound represented by the following general formula (8) in addition to the compound represented by the following general formula (7).

R ⁵ _4-n3 -M- (R ³ ) _n3 (8)

(Wherein M is a metal or silicon, R ³ is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and R ⁵ is Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH or Represents any group of OCOCH ₃ groups, n3 is either 1, 2 or 3)

  The content of the compound represented by the general formula (8) is not particularly limited, but is 5 to 20 with respect to the total amount of the compound represented by the general formula (7) and the compound represented by the general formula (8). It is preferable that it is mass%.

  It is desirable to heat this organic-inorganic composite at a high temperature that is equal to or higher than the operating temperature. As a heating method, in addition to hot air heating by a normal heat source, far infrared heating, electromagnetic induction heating, microwave heating, or the like may be used. Moreover, you may use together. Moreover, you may wash the film | membrane obtained in these processes with water as needed. The water used at that time is preferably water containing no metal ions, such as distilled water or ion-exchanged water. Further, after the film is obtained in this way, it may be further crosslinked by irradiation with ultraviolet rays or electron beams. The film thickness is in the range of 0.1 μm to 50 μm, preferably 0.5 μm to 5.0 μm.

  A semiconductor device according to the present invention includes a semiconductor substrate or a first wiring conductor formed on the semiconductor substrate and an interlayer insulating film interposed between the second wiring conductors, and the interlayer insulating film is made of silicon. -It is characterized by comprising an organic-inorganic composite containing a cross-linked structure with an oxygen bond and a carbon atom covalently bonded thereto.

According to such a configuration, the dielectric constant of the interlayer insulating film can be reduced, so that the interlayer capacitance can be reduced and a semiconductor device driven at high speed can be provided. Also, the moisture resistance is high.
Furthermore, since it can be formed at a low temperature, a highly reliable film can be formed without affecting the base.

The semiconductor device of the present invention is formed by forming a passivation film on the surface of a semiconductor substrate on which an element is formed, and the passivation film has an organic structure having a crosslinked structure formed by a silicon-oxygen bond and a carbon atom covalently bonded thereto. It is composed of an inorganic composite.
According to such a configuration, it is possible to form an effective film having excellent moisture resistance and high reliability.

  According to the present invention, an organic-inorganic composite having a small non-dielectric constant, high moisture resistance, high flexibility, excellent mechanical properties, high porosity, high skeleton density, and an independent pore structure is provided. Is possible. In addition, it is possible to provide a highly reliable semiconductor device including an insulating film having high moisture resistance and high mechanical strength and a low dielectric constant.

First Embodiment Hereinafter, a semiconductor device according to an embodiment of the present invention will be described in detail with reference to the drawings.
As a first embodiment of the present invention, a semiconductor device including a semiconductor integrated circuit including a MOSFET using this low dielectric constant thin film as an interlayer insulating film will be described.

  In the present embodiment, a crosslinkable precursor as described later is prepared, and the amount of catalyst is such that 0.5 to 1.5 equivalents of water is present with respect to the crosslinkable silyl group that is the crosslinkable precursor. A low dielectric constant thin film containing a crosslinked structure formed by silicon-oxygen bonds and a carbon atom covalently bonded to this, and having vacancies as independent structures. As shown in FIG. 1, this is used as an interlayer insulating film 7 to form a semiconductor device.

  As shown in FIG. 1, this semiconductor device is formed by forming an element region such as a MOSFET on a silicon substrate 1 on which an insulating film 2 for element isolation is formed, and forming a multilayer wiring on the surface. As the interlayer insulating film 7, 1,4-bis (trimethoxysilylethyl) benzene or 1,8-bis (diethoxymethylsilyl) octane shown in this embodiment is used to cause a condensation reaction on the surface of the semiconductor device. The low dielectric constant thin film formed is used.

  This semiconductor device includes a gate electrode 4 formed through a gate oxide film 3 formed on the surface of a 4-inch and 6-inch silicon substrate 1, low-concentration impurity diffusion regions 5a and 5b, high-concentration impurity diffusion regions 6a, A MOSFET composed of a source / drain region having an LDD structure of 6b, a first layer wiring 8 in contact with one of the source / drain regions, and an interlayer insulating film made of a low dielectric constant thin film of the present invention; And a second layer wiring 10 formed through the contact hole 9. Reference numeral 11 denotes a film formed so as to cover the semiconductor device.

A manufacturing process of this semiconductor device will be described with reference to FIGS.
First, the gate electrode 4 formed on the surface of the silicon substrate 1 through the gate oxide film 3 is formed. Then, impurity diffusion is performed using the gate electrode 4 as a mask to form low-concentration impurity diffusion regions 5a and 5b constituting the source / drain regions (FIG. 2A).

  Subsequently, a silicon oxide film is formed on this upper layer by CVD, and anisotropic etching is performed to form a side wall 3s on the side wall of the gate electrode (FIG. 2B).

Then, high-concentration impurity diffusion is performed using the gate electrode 4 with the sidewall 3s formed as a mask to form high-concentration impurity diffusion regions 6a and 6b, and source / drain regions having an LDD structure are formed (FIG. 2). c)).
Next, a low dielectric constant thin film having an independent pore structure is formed as the interlayer insulating film 7 using the method of the present invention. Then, a contact hole 9 was formed in the interlayer insulating film made of the low dielectric constant thin film by photolithography (FIG. 2D).

Thereafter, as shown in FIG. 2E, the second layer wiring 10 was formed. Finally, this low dielectric constant thin film was formed as the film 11 using the same method.

According to this method, it is possible to form a low dielectric constant thin film having a strength capable of CMP, high toughness, and high mechanical strength at a low temperature. Also, it acts as a buffer film that relieves stress on the upper and lower layers, and it is possible to provide a highly reliable semiconductor device.
[Example]

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, the scope of the present invention is not limited to these.
The prepared interlayer insulating film was evaluated by the following four methods.
(1) Strength evaluation The Young's modulus was measured using a nano indentator (manufactured by MTS System Corp., Nano Indenter).

(2) Heat resistance evaluation The temperature at the time of 1% weight reduction was measured by TGA (EXTRA6200 manufactured by Seiko Instruments Inc.) under a nitrogen atmosphere.

(3) Dielectric Constant Evaluation The dielectric constant at a frequency of 100 KHz was measured for a smoothly prepared film using an impedance measuring device (HP4195A, manufactured by Hewlett Packard).

(4) Evaluation of CMP resistance As a polishing machine, a 6-inch surface plate / 1-head single-wafer CMP apparatus is used, a substrate is set in a holder to which a substrate suction pad is attached, and a CMP pad (IC1000 / Suba400; Rodale) The above-mentioned holder was placed with the film surface facing downward, and the processing load was set to 6900 Pa (1 psi = 6895 Pa). The polishing liquid (C1010; manufactured by Showa Denko) was dripped onto the CMP pad at a speed of 150 cc / min, and the surface plate and the head rotation speed were polished at 50 rpm for 1 minute. The polished wafer was thoroughly washed with pure water and dried.
The wafer surface after polishing in this way by CMP was observed with an optical and electron microscope.
Occurrence of cracks and peeling None: ○, Yes: ×

(5) Porosity Obtaining the specific surface area by the BET theory, applying the DH (Dollimore & Heal Method) method from the obtained specific surface area, calculating the pore size distribution, smoothing the obtained pore size distribution, The integrated value was defined as a pore volume ΣVp, and the pore volume ΣVp was expressed as a percentage of the interlayer insulating film volume.

(6) Evaluation of film formation uniformity Visual evaluation was performed after film formation and drying.
It was judged that a film was formed uniformly; ○
Observed non-uniformity such as wavy, uneven color, streaks; (described in the table)

1.0 g of 1,4-bis (trimethoxysilylethyl) benzene was dissolved in 1.0 g of 1-butanol to prepare a 1-butanol solution.
Meanwhile, 0.2 g of 1N hydrochloric acid was added to 1.0 g of 1-butanol. These were combined and stirred for 30 seconds while cooling with ice to prepare a precursor solution. This precursor solution was applied to the surface of the semiconductor device by spin coating. Here, the rotation speed was increased to 3000 rpm in 30 seconds, and was held for 10 seconds when reaching 3000 rpm. It was cured at 120 ° C. for 1 hour and baked in a nitrogen atmosphere at 400 ° C. for 30 minutes. As a result, a transparent low dielectric constant thin film having a thickness of 2 μm was formed.

  Further, when CMP was performed under a pressure of 1 psi, it was possible to finish the film smoothly without any peeling of the film, and it was confirmed that the film had CMP resistance.

  According to this configuration, since the dielectric constant of the interlayer insulating film 7 is low, the parasitic capacitance formed between the first layer wiring and the second layer wiring is suppressed to be small, and a semiconductor device capable of high speed driving is provided. It becomes possible.

(Synthesis of bifunctional precursor)
To a toluene solution of 11.0 g of 1,7-octadiene (manufactured by Wako Pure Chemical Industries) and 26.9 g of diethoxymethylsilane (manufactured by Shin-Etsu Silicon Co., Ltd.), chloroplatinic acid (manufactured by Wako Pure Chemical Industries) and divinyltetramethyldisiloxane ( 0.05 mmol of a Karsted catalyst (Karsted: USP3777552) solution prepared from Ge1est Co., Ltd. was mixed and stirred under a nitrogen atmosphere at 30 ° C. for 24 hours. The reaction mixture thus obtained was purified by distillation to obtain 1,8-bis (diethoxymethylsilyl) octane. The structure was confirmed by 1H-NMR (Nuclear Magnetic Resonance Spectrometer DRX-300 manufactured by Bruker).

  Then, 1.0 g of 1,8-bis (diethoxymethylsilyl) octane, which is a bifunctional precursor formed by the above-described steps, was dissolved in 1.0 g of 1-butanol to prepare a 1-butanol solution.

  Meanwhile, 0.2 g of 1N hydrochloric acid was added to 1.0 g of 1-butanol. These were combined and stirred for 30 seconds while cooling with ice to prepare a precursor solution. This precursor solution was applied to the surface of the semiconductor device by spin coating and cured at room temperature (20 ° C.) for 2 hours to form a transparent low dielectric constant thin film having a thickness of 2 μm.

Then, after the second layer wiring 10 was formed, this low dielectric constant thin film was finally formed as the film 11 using the same method. According to this configuration, since the dielectric constant of the interlayer insulating film 7 is low, the parasitic capacitance formed between the first layer wiring and the second layer wiring is suppressed to be small, and a semiconductor device capable of high speed driving is provided. It becomes possible.
Furthermore, in the cross-linking immobilization reaction intended to further progress the condensation reaction and evaporate the solvent, it is desirable to bake at 400 ° C. for 30 minutes under a nitrogen flow.

1,5-bis (diethoxymethylsilyl) octane (0.45 g) and n-octyltriethoxysilane (0.05 g) synthesized in Example 2 were dissolved in 1-butanol (4.5 g), and the solution was dissolved. Prepared.
On the other hand, 0.1 g of 1N hydrochloric acid was added to the above solution and stirred at room temperature for 10 minutes to prepare a precursor solution. This precursor solution was applied onto the surface of the semiconductor device by spin coating and cured at room temperature (20 ° C.) for 1 hour to form a colorless, transparent, and elastic low dielectric constant thin film.

Then, after the second layer wiring 10 was formed, this low dielectric constant thin film was finally formed as the film 11 using the same method. According to this configuration, the dielectric constant of the interlayer insulating film 7 is 3.01, and a semiconductor device capable of being driven at high speed with a small parasitic capacitance formed between the first layer wiring and the second layer wiring is provided. It becomes possible.
Further, in the cross-linking immobilization reaction intended to further proceed the condensation reaction and evaporate the solvent, it is desirable to bake at 425 ° C. for 30 minutes under a nitrogen flow.

In Example 2, an interlayer insulating film 7 was formed in the same manner as in Example 2 except that an iso-propanol precursor solution was formed instead of 1-butanol.
In the case of a 4-inch substrate, a flat film with a uniform coating film surface was obtained after coating on the surface of the semiconductor device. In the case of a 6-inch substrate, after coating on the surface of the semiconductor device, the coating thickness was partially thick and wavy at the inner portion about 5 mm from the outer peripheral edge, but a uniform film was obtained otherwise. It was.

In Example 2, an interlayer insulating film 7 was formed in the same manner as in Example 2 except that a 1-hexanol precursor solution was formed instead of 1-butanol.
In the case of a 4-inch substrate, a uniform and flat film was obtained after coating on the surface of the semiconductor device. In the case of a 6-inch substrate, after coating on the surface of the semiconductor device, color unevenness was observed in the portion about 5 mm inside from the outer peripheral edge, and the coating thickness seemed to increase continuously toward the outer peripheral edge. Otherwise, a uniform film was obtained.
(Comparative Example 1)

In Example 2, an interlayer insulating film 7 was prepared in the same manner as in Example 2 except that a 1,2-bis (trimethoxysilyl) ethane precursor solution was prepared instead of 1,8-bis (diethoxymethylsilyl) octane. Formed.
In this case, after coating on the surface of the semiconductor device, when CMP is performed under a pressure of 1 psi, it becomes a brittle film having no CMP resistance, and there are many peelings of the film at a level of about 0.3 mm ² that can be observed with an optical microscope. I was able to observe.

  The interlayer insulating films formed by the methods of Examples 1 to 5 and Comparative Example 1 formed as described above were evaluated by the six evaluation methods described above. The evaluation results are shown in the following table.

As apparent from Table 1, the interlayer insulating films of Examples 1 to 3 have a low dielectric constant and high reliability without cracks or peeling. Further, effective values of heat resistance and Young's modulus were obtained as an interlayer insulating film or a passivation film.
On the other hand, the interlayer insulating film of Comparative Example 1 was cracked or peeled off, and the mechanical strength required for the interlayer insulating film was not sufficient.

In addition, about the composition of a precursor solution, it can prepare suitably, without being limited to the composition of the said embodiment. However, although the catalyst for hydrolyzing the silyl group is composed of Bronsted acid, the catalyst is not limited to Bronsted acid and can be used in various ways. In addition, although Bronsted acid is used for dehydration condensation, the present invention is not limited to Bronsted acid and can be used as appropriate. Further, when the precursor solution is formed, preliminary crosslinking may be performed by heating.
Further, the film may be heated and fired after film formation, and the heating atmosphere is preferably in a nitrogen atmosphere.
In addition, by adding a heating step, heat resistance and moisture resistance are improved, and leakage current can be reduced.

[Second Embodiment]
In the first embodiment, the low dielectric constant thin film is formed by spin coating. However, the low dielectric constant thin film may be immersed in the precursor solution. Alternatively, a dip coating method may be used in which a film is immersed in the precursor solution.

  That is, the substrate is lowered at a desired speed with respect to the liquid level of the precursor solution, submerged in the solution, and allowed to stand. Then, after the desired time has elapsed, the substrate is lifted vertically at a desired speed and removed from the solution. And if necessary, an organic-inorganic composite is formed by heating and baking.

In the above embodiment, the application example of the organic-inorganic composite film to the interlayer insulating film of the semiconductor device has been described. However, not only a silicon device but also a device using a compound semiconductor such as an HBT or a semiconductor laser, a microwave IC, or the like. The present invention can also be applied to a microwave transmission line using a high-frequency device, a film carrier, or a multilayer printed board.
In addition, the low dielectric constant thin film of the present invention is effective not only as a film but also as a bulk body or a tape-like body and attached to a semiconductor device.

  The low dielectric constant thin film of the present invention is applicable to silicon devices, HBTs, devices using compound semiconductors, high frequency devices, microwave transmission lines, multilayer printed boards, and the like.

It is a figure which shows the semiconductor device of embodiment of this invention. It is a manufacturing process figure of the semiconductor device of an embodiment of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Insulating film 3 Gate oxide film 4 Gate electrode 5a, 5b Low concentration impurity diffusion region (source / drain region)
6a, 6b High concentration impurity diffusion region (source / drain region)
7 Interlayer insulating film 8 First layer wiring 9 Contact hole 10 Second layer wiring 11 Film

Claims (27)

An organic-inorganic composite having a crosslinked structure with a metal-oxygen bond, comprising a compound represented by the following general formula (1):

(In the formula, M is a metal or silicon, X is an —O— bond or OH group involved in crosslinking, and R ¹
Is a carbon atom-containing molecular chain group having 8 to 20 carbon atoms, R ² represents any one of methyl, ethyl, propyl, and phenyl groups, and n1 and n2 are either 0, 1, or 2, is there. )   2. The organic-inorganic composite according to claim 1, wherein M is silicon. The organic-inorganic composite according to claim 1, wherein R ¹ in the general formula (1) is a polymethylene group. The organic-inorganic composite according to claim 3, wherein the polymethylene group is represented by the following general formula (2).

(In the formula, n represents an integer.) The organic-inorganic composite according to any one of claims 1 to 4, wherein the compound is a compound represented by the following general formula (3).

(In the formula, X is an —O— bond or OH group involved in crosslinking, and n1 and n2 are either 0, 1, or 2.) The organic-inorganic composite according to claim 1 or 2, wherein R ¹ in the general formula (1) is a hydrocarbon group containing a benzene ring. The organic-inorganic composite according to claim 6, wherein the hydrocarbon group is represented by the following general formula (4).

  In the said General formula (4), n and m exist in the range of the integer of 1-20, The organic inorganic composite of Claim 7 characterized by the above-mentioned.   In the said General formula (4), n and m are 2, respectively, The organic-inorganic composite of Claim 8 characterized by the above-mentioned. The organic-inorganic composite according to any one of claims 1, 2, 6, 7, 8, and 9, wherein the compound is a compound represented by the following general formula (5).

(In the formula, X is an —O— bond or OH group involved in crosslinking, and n1 and n2 are either 0, 1, or 2.) Furthermore, it has a compound shown by following General formula (6), The organic inorganic composite of Claim 1 characterized by the above-mentioned.
_{X 4-n3 - M - (} R 3) n3 ··· (6)
(Wherein M is a metal or silicon, X is an —O— bond or OH group involved in cross-linking, and R ³
Is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and n3 is either 1, 2 or 3. )   The content of the compound represented by the general formula (6) is 5 to 20% by mass with respect to the total amount of the compound represented by the general formula (1) and the compound represented by the general formula (6). The organic-inorganic composite according to claim 11. A method for producing the organic-inorganic composite according to any one of claims 1 to 12,
Preparing a precursor comprising a mixture comprising a plurality of crosslinkable silyl groups and an organic-inorganic composite crosslinkable compound having a carbon atom covalently bonded thereto;
Depositing the precursor on a substrate;
And a condensation step of hydrolyzing / condensing the crosslinkable silyl group to form an organic-inorganic composite.   The method for producing an organic-inorganic composite according to claim 13, wherein the precursor contains a solvent having a boiling point of 100C to 130C.   The method for producing an organic-inorganic composite according to claim 13, wherein the condensation step includes a step of adding 0.5 to 1.5 equivalents of water to the crosslinkable silyl group.   The method for producing an organic-inorganic composite according to claim 15, wherein the condensation step further includes a step of adding a catalyst.   The method for producing an organic-inorganic composite according to claim 16, wherein the catalyst is a Bronsted acid. The method for producing an organic-inorganic composite according to any one of claims 13 to 17, wherein the precursor solution includes at least a compound represented by the following general formula (7).

(In the formula, M is a metal or silicon, R ¹ is a carbon atom-containing molecular chain group having 8 to 20 carbon atoms, R ² represents any group of methyl, ethyl, propyl, or phenyl group, R ⁵ represents any one of Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH and OCOCH ₃ groups, and n1 and n2 are either 0, 1, or 2) In the said General formula (7), R < ¹ > is represented by following General formula (4), The manufacturing method of the organic inorganic composite of Claim 18 characterized by the above-mentioned.

  20. The method for producing an organic-inorganic composite according to claim 19, wherein the structure of the general formula (4) is a p-form. Wherein R ¹ in the general formula _{(7) - (CH 2)} 8 - in the production method of the organic-inorganic composite according to claim 18, characterized in that a octamethylene represented. In the general formula (7), the R ² is a methyl group, R ⁵ is a manufacturing method of the organic-inorganic composite according to claim 18, characterized in that represents the OCH ₃ or OC ₂ H ₅ group. The method for producing an organic-inorganic composite according to claim 18, wherein the precursor solution further includes a compound represented by the following general formula (8).
R ⁵ _4-n3 -M- (R ³ ) _n3 (8)
(Wherein M is a metal or silicon, R ³ is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and R ⁵ is Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH or Represents any group of OCOCH ₃ groups, n3 is either 1, 2 or 3)   The content of the compound represented by the general formula (8) is 5 to 20% by mass with respect to the total amount of the compound represented by the general formula (7) and the compound represented by the general formula (8). The method for producing an organic-inorganic composite according to claim 23.   13. A semiconductor device using the organic-inorganic composite having a crosslinked structure with a silicon-oxygen bond according to any one of claims 1 to 12. An interlayer insulating film interposed between the first wiring conductor formed on the semiconductor substrate or the semiconductor substrate and the second wiring conductor;
26. The semiconductor device according to claim 25, wherein the interlayer insulating film is composed of an organic-inorganic composite having a cross-linked structure by the silicon-oxygen bond.   27. A passivation film is formed on a surface of a semiconductor substrate on which an element is formed, and the passivation film is composed of an organic-inorganic composite having a crosslinked structure by the silicon-oxygen bond. A semiconductor device according to 1.

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