JP2004136661A - Insulating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating film or the like which sufficiently reduces a dielectric constant, causes no hydrolysis, and is excellent in stability. <P>SOLUTION: The insulating film 120 has a two-layer structure wherein a B layer 112 containing a non-borazine compound such as SiOF or organic SOG and an A layer 111 containing a borazine compound are laminated in this sequence alternately on a silicon wafer 100 having a silicon base layer. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an insulating film and an electronic component.

With the recent miniaturization, high output, and high-speed signals of communication devices, the realization of film flattening by CMP has been combined with the insulation coating of electronic components (IMD: metal interlayer insulating film, ILD: metal lower layer). Insulation film, PMD: pre-metal insulation film, etc.) are required to have not only heat resistance, mechanical properties, hygroscopicity, adhesiveness, moldability, high etch selectivity, etc. but also particularly low dielectric constant.

In general, the propagation speed (v) of a signal on a wiring and the relative dielectric constant (ε) of an insulating material with which the wiring material contacts have a relationship represented by v = k / √ε (k is a constant). This is because, in order to increase the signal propagation speed and reduce the wiring delay, it is necessary to increase the frequency range to be used or to lower the relative dielectric constant of the insulating material as much as possible.

A low dielectric constant material which is currently put into practical use on a mass production basis as such an insulating coating material is a SiOF film (CVD method) having a relative dielectric constant of about 3.5. Studies on organic SOG (Spin \ On \ Glass) of 0.5 to 3.0, organic polymers, and the like are in progress.

In addition, as another low dielectric constant material, borazine having a molecular structure in which carbon atoms of benzene are substituted with nitrogen atoms and boron atoms is known to have a calculated dielectric constant lower than that of benzene. (See, for example, Patent Document 1.) A heat-resistant borazine obtained by mixing B, B ', B "-trialkynylborazines and hydrosilanes in the presence of a platinum catalyst and applying the solution. A silicon-containing thin film containing silicon is also known (for example, see Patent Document 2).
JP 2000-340689 A JP 2002-155143 A

By the way, the above-mentioned organic SOG is promising as a low dielectric constant material, but in order to cope with further miniaturization and multilayering of electronic components including semiconductor devices such as memory elements and logic elements, further lowering of the dielectric constant is required. Aspired. Therefore, it can be expected that the dielectric constant can be further reduced by combining the organic SOG film with the borazine-containing silicon polymer described in JP-A-2002-155143.

However, the borazine-containing silicon polymer before curing has a slight hydrolyzability, and when the borazine-containing silicon polymer before curing is mixed into a composition (varnish) of an organic SOG precursor containing water in advance, The borazine-containing silicon polymer may undergo hydrolysis, and as a result, the performance as a low dielectric constant material may be reduced.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an insulating film which is capable of achieving a sufficiently low dielectric constant, has excellent stability without causing hydrolysis, and an electronic component using the same. Aim.

In order to solve the above problems, an insulating coating according to the present invention is different from at least one first insulating layer containing a compound having a borazine skeleton in a molecular structure, and the first insulating layer (that is, the first insulating layer is different from the first insulating layer). And at least one second insulating layer comprising a compound having no borazine skeleton in its molecular structure).

The insulating coating having such a configuration, for example, in the case of a two-layer alternating laminated structure as an example, a second insulating layer (for example, a borazine-containing silicon polymer layer) is formed on a first insulating layer (for example, a borazine-containing silicon polymer layer) formed in advance. (Organic SOG film), or conversely, a first insulating layer is formed on a previously formed second insulating layer. In this case, the components of the first insulating film and the components of the second insulating film are prevented from being mixed, and the contact between the two components is sufficiently prevented. Therefore, even when the second insulating layer contains moisture, the migration of the moisture to the first insulating layer is suppressed, and the decomposition of the compound having a borazine skeleton in the molecular structure and showing hydrolyzability is prevented. Is prevented. Therefore, the first insulating layer and the second insulating layer each exhibit a unique dielectric constant, and the dielectric constant of the entire insulating film is determined by the dielectric constant, the number of layers, and the like.

Furthermore, according to the findings of the present inventors, the first insulating layer composed of the borazine-containing silicon polymer layer and the like has extremely excellent adhesion to other layers, in other words, excellent adhesion to other layers. Things. Therefore, the first insulating layer can function not only as an insulator, but also as an excellent adhesive layer for sufficiently fixing the other layer, that is, the second insulating layer, to the base or the like.

で表される繰り返し単位を有するものであると、成膜性及び化学的安定性の観点から好ましい。 Further, a compound having a borazine skeleton in a molecular structure is represented by the following formula (1):

It is preferable to have a repeating unit represented by the following from the viewpoints of film formability and chemical stability.

Here, in the formula, R1 represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom, R2 represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom, and R3 and R4 represent an alkyl group, an aryl group, or an aralkyl group. R5 represents a substituted or unsubstituted aromatic divalent group, an oxypoly (dimethylsiloxy) group or an oxygen atom, and R6 represents an alkyl group. , An aryl group, an aralkyl group or a hydrogen atom, a represents a positive integer, b represents 0 or a positive integer, p represents 0 or a positive integer, and q represents 0 or a positive integer.

電子 Further, the electronic component according to the present invention is one in which the insulating coating according to the present invention is provided on a base such as a silicon wafer.

According to the insulating coating of the present invention, since the first and second insulating layers are alternately laminated, a sufficiently low dielectric constant can be achieved, and the occurrence of hydrolysis can be prevented to increase the stability. Can be. In addition, since the first insulating layer exhibits excellent adhesion to the second insulating layer and the base, the mechanical strength of the insulating coating is increased, and the peeling resistance to polishing such as CMP can be improved.

The insulating coating of the present invention includes at least one first insulating layer (hereinafter, referred to as “A layer”) containing a compound having a borazine skeleton in a molecular structure, and at least one first insulating layer different from the first insulating layer. And two second insulating layers (hereinafter, referred to as a “B layer”). Hereinafter, each layer, its constituent components, and the like, and preferred embodiments of the electronic component of the present invention will be described.

<A layer>
The A layer constituting the insulating coating of the present invention contains a compound having a borazine skeleton in its molecular structure, and has a substituted or unsubstituted borazine skeleton in a main chain or a side chain. Any of a borazine compound monomer and a polymer may be used, and it is desirable to use a polymer from the viewpoint of the film forming property and film strength of the A layer. Examples of such a polymer include, for example, Chemical Review, vol. 73-91 (1990). And CHEMTECH, July 1994, pp. 29-37. And the like. Specifically, the following polymers are suitable.

で表される繰り返し単位を有してなる有機ケイ素ボラジン系ポリマーが、成膜性、化学的安定性に優れており、かかる観点より一層好適である。 Also, preferably, the following formula (1) or formula (2);

An organosilicon borazine-based polymer having a repeating unit represented by the formula (1) is excellent in film formability and chemical stability, and is more preferable from this viewpoint.

は、以下のいずれかを示し、

これと同様に、

は、以下のいずれかを示す。

Note that in equations (1) and (2),

Indicates one of the following,

Similarly,

Indicates one of the following:

は、以下のいずれかを示す。

And

Indicates one of the following:

Further, the broken line in the formula (1) means that a bond is formed at the carbon derived from the alkynyl group in the borazine residue, and the broken line in the formula (2) is a bond formed at the carbon derived from the alkenyl group in the borazine residue. Means that it has occurred.

In the formulas (1) and (2), R ¹ represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom. In this case, the alkyl group has 1 to 24, preferably 1 to 12 carbon atoms. The aryl group has 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms. Further, the aralkyl group has 7 to 24 carbon atoms, preferably 7 to 12 carbon atoms. More specifically, as the group R ¹ , an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an octyl group, an aryl group such as a phenyl group, a naphthyl group, a biphenyl group, a benzyl group, and a phenethyl group And the like. Among them, a methyl group, an ethyl group, a phenyl group or a hydrogen atom is more preferable.

In the formulas (1) and (2), R ² represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom, and the alkyl group has 1 to 24, preferably 1 to 12 carbon atoms. In this case, the aryl group has 6 to 20, preferably 6 to 10 carbon atoms. The aralkyl group has 7 to 24 carbon atoms, preferably 7 to 12 carbon atoms. More specifically, as the group R ² , an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an octyl group, an aryl group such as a phenyl group, a naphthyl group, a biphenyl group and an anthracenyl group, and a benzyl group And an aralkyl group such as a phenethyl group and a fluorenyl group, and a hydrogen atom. Of these, a methyl group, a phenyl group and a hydrogen atom are more preferable.

Further, in the formulas (1) and (2), R ³ and R ⁴ represent the same or different monovalent groups selected from an alkyl group, an aryl group, an aralkyl group, and a hydrogen atom. Groups, aryl groups or hydrogen atoms are more preferred. In this case, the alkyl group has 1 to 24, preferably 1 to 12 carbon atoms. The aryl group has 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms. Further, the aralkyl group has 7 to 24 carbon atoms, preferably 7 to 12 carbon atoms. More specifically, as groups R ³ and R ⁴ , alkyl groups such as methyl group, ethyl group, isopropyl group, t-butyl group, octyl group, aryl groups such as phenyl group, naphthyl group, biphenyl group, and benzyl group And an aralkyl group such as a phenethyl group, a hydrogen atom and the like. Among them, a methyl group, a phenyl group and a hydrogen atom are more preferable.

Further, in the formulas (1) and (2), R ⁵ represents a substituted or unsubstituted aromatic divalent group, an oxypoly (dimethylsiloxy) group, or an oxygen atom. In this case, the aromatic divalent group has 6 to 24 carbon atoms, preferably 6 to 12 carbon atoms. The aromatic divalent group includes, in addition to a divalent aromatic hydrocarbon group (such as an arylene group), an arylene group containing a heteroatom such as oxygen as a linking group. Examples of the substituent that may be bonded to the aromatic divalent group include an alkyl group, an aryl group, and an aralkyl group. More specifically, as the base R ^5, a phenylene group, a naphthylene group, an arylene group such as biphenylene group, a substituted arylene group such as diphenyl ether group, such as an oxygen atom., A phenylene group, diphenyl ether group or oxygen among these Atoms are more preferred.

Furthermore, in the formulas (1) and (2), R ⁶ represents an alkyl group, an aryl group or an aralkyl group. In this case, the alkyl group has 1 to 24, preferably 1 to 12 carbon atoms. The aryl group has 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms. Further, the aralkyl group has 7 to 24 carbon atoms, preferably 7 to 12 carbon atoms. More specifically, as the group R6, an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an octyl group, an aryl group such as a phenyl group, a naphthyl group, a biphenyl group, a benzyl group, a phenethyl group, and the like Aralkyl groups and the like.

In the formulas (1) and (2), a and b each represent the number of repeating units, and a is a positive integer, preferably from 1 to 20,000, more preferably from 3 to 10,000, and particularly preferably. Is 5 to 10,000. B is 0 or a positive integer, preferably 0 to 1000, more preferably 0 to 100. However, a and b indicate their constituent ratios, and are not limited to any form of the bonding state (block copolymerization, random copolymerization, etc.).

In such a copolymer, the ratio (a: b) of the respective numbers of a and b is not particularly limited, and the a / b ratio is large, that is, the ratio of the chain structure in the polymer main chain is low. When the amount is relatively large, it is expected that the processability of the copolymer will be improved by increasing the solubility of the copolymer in the solvent and lowering the melting point. On the other hand, when the a / b ratio is small, that is, when the ratio of the crosslinked structure in the polymer main chain is relatively large, it is expected that the heat resistance and the combustion resistance of the copolymer will be improved. Therefore, depending on the use or the like, or the structure of each monomer unit of the copolymer and the combination thereof, the optimum a / b ratio of the copolymer that gives good processability, heat resistance, and combustion resistance is obtained. The range can be set as appropriate.

Furthermore, in the formulas (1) and (2), p represents 0 or a positive integer, q represents 0 or a positive integer, and has a relationship of p + q + 2 = n with n described later. The preferable range of p is 0-10, more preferably 1-8. The preferable range of q is 0 to 10, more preferably 1 to 8.

　又は下記式（４）；

　で表される２価の基であり、同一分子鎖において、Ｚ¹が式（３）又は（４）のいずれか一方の構造で構成されていても、或いは、両方の構造が同一分子鎖内に含まれていても構わない。なお、式（３）及び（４）におけるＲ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、ｐ及びｐは前述したものと同様である。 Furthermore, in the formulas (1) and (2), Z ¹ is the following formula (3);

Or the following formula (4);

In the same molecular chain, Z ¹ may be composed of either ^one of the formulas (3) and (4), or both structures may be in the same molecular chain. May be included. Note that R ³ , R ⁴ , R ⁵ , R ⁶ , p and p in the formulas (3) and (4) are the same as those described above.

The molecular weight (Mn; number average molecular weight of a value measured by gel permeation chromatography (GPC) and converted using a calibration curve of standard polystyrene) of the polymer having a borazine skeleton is preferably 500 to 5,000,000. , More preferably 1,000 to 1,000,000. When the molecular weight (Mn) is excessively low, for example, less than 500, heat resistance and mechanical properties of an insulating film described later tend to be inferior. For example, when such an insulating film is used as an interlayer insulating film, prebaking is difficult. There is a possibility that peeling or the like may easily occur when flattening after film formation is performed by CMP. On the other hand, if the molecular weight (Mn) is excessively high, for example, more than 5,000,000, the workability of the insulating film deteriorates. For example, a via hole for forming a metal plug such as W is formed in the insulating film in a desired shape. Control may be difficult.

Further, the layer A (first insulating layer) containing the compound having the borazine skeleton is provided on a base such as a silicon wafer or a layer B (second insulating layer) described later on by the above-mentioned borazine skeleton. And a thin film composed of a single or a plurality of components that do not promote the decomposition of the compound having a borazine skeleton or reduce the performance as an insulating layer by a CVD method or a spin coating method. Can be formed.

<B layer>
The layer B constituting the insulating coating of the present invention is an insulating layer which has a different composition or component from the layer A and does not contain a compound having a borazine skeleton in its molecular structure. Specifically, a non-borazine-based compound (non-borazine compound) film such as SiOF, organic SOG, or non-borazine-based organic polymer formed by a CVD method, which is formed of a material used as a general low dielectric constant material Is done. More specifically, HSG series manufactured by Hitachi Chemical Co., Ltd., LKD series manufactured by JSR, SiLK manufactured by Dow Chemical Company, T series manufactured by Honeywell, FLARE and the like can be mentioned.

The layer B (the second insulating layer) having such a structure is formed on a substrate such as a silicon wafer or the above-mentioned layer A (the first insulating layer) on a low dielectric constant material which does not contain the compound having a borazine skeleton. Can be formed by coating and curing using a CVD method or a spin coating method. When the spin coating method is used, it is desirable to sufficiently remove moisture from the layer B during heat curing. If the layer A containing the borazine compound is laminated with excessive moisture remaining, a part of the borazine compound may be hydrolyzed in some cases, which is not preferable.

<Insulating coating>
As described above, the insulating film of the present invention is obtained by alternately laminating the A layer containing the compound having the borazine skeleton in the molecular structure and the B layer containing no compound having the borazine skeleton unlike the A layer. Things. The number of layers of the insulating coating is not particularly limited as long as the layer A and the layer B are alternately stacked, but from the viewpoint of simplification of the process, the number of layers is preferably two to five. Further, the layer A is extremely excellent in the ability to adhere to another layer (that is, the ability to adhere to another layer). Therefore, by alternately laminating the A layer and the B layer, the adhesion between the layers is strengthened. As a result, the mechanical strength of the entire insulating film can be improved. For example, when the insulating film is subjected to polishing such as CMP, delamination of the A layer or the B layer can be sufficiently suppressed.

Furthermore, in the order of lamination of the A layer and the B layer, that is, when provided on the substrate, which of the A layer and the B layer is applied directly on the substrate, or the uppermost layer of the insulating film is formed of the A layer and the B layer. Although there is no particular limitation as to which one, adhesion to a substrate and adhesion to other layers (for example, a protective film, a hard mask, a resist film, a wiring film, etc.) provided on an insulating film are improved. From the viewpoint of enhancement, it may be preferable that the both end layers of the insulating coating be the A layers.

FIGS. 1 to 4 are schematic cross-sectional views each showing an example of the configuration of an insulating film according to the present invention. The insulating coatings 110 and 120 in FIGS. 1 and 2 are formed by alternately stacking A layers 111 (first insulating layers) and B layers 112 (second insulating layers) on a silicon wafer 100 having a silicon base layer. The insulating film 110 has a layer structure, in which the insulating film 110 is laminated in the order of the A layer 111-B layer 112, and the insulating film 120 is laminated in the reverse order. The insulating coatings 130 and 140 in FIGS. 3 and 4 have a two-layer structure. The insulating coating 130 is laminated in the order of layer A 111 -layer B 112 -layer A 111. The layers are stacked in the order of 112-A layer 111-B layer 112. The illustration of the insulating coating having a laminated structure of three or more layers is omitted.

<Electronic components>
Examples of the electronic component of the present invention using the insulating coating of the present invention include those having an insulating coating such as a semiconductor element, a liquid crystal element, and a multilayer wiring board. The insulating film of the present invention is used as an insulating film such as a surface protective film, a buffer coat film, and an interlayer insulating film in a semiconductor device, as a surface protective film and an insulating film in a liquid crystal device, and as an interlayer insulating film in a multilayer wiring board. It can be preferably used as a film.

Specifically, the semiconductor element includes individual semiconductor elements such as a diode, a transistor, a capacitor, a compound semiconductor element, a thermistor, a varistor, and a thyristor, a DRAM (dynamic random access memory), and an SRAM (static random access memory). Memory (memory), EPROM (erasable programmable read only memory), mask ROM (mask read only memory), EEPROM (electrically erasable programmable read only memory), flash memory, etc. ) Devices, microprocessors, theoretical (circuit) devices such as DSP and ASIC, integrated circuit devices such as compound semiconductors represented by MMIC (monolithic microwave integrated circuit), hybrid integrated circuits (Hybrid IC), light emitting diode, a photoelectric conversion element such as a charge coupled device, the light emitting element, such as a semiconductor laser element and the like. Examples of the multilayer wiring board include a high-density wiring board such as an MCM.

FIG. 5 is a schematic sectional view showing a preferred embodiment of the electronic component according to the present invention. The memory capacitor cell 8 (electronic component) functions as a gate electrode 3 (word line) provided on a silicon wafer 1 (base) on which diffusion regions 1A and 1B are formed via a gate insulating film 2B made of an oxide film. ) And a counter electrode 8C provided thereabove, an interlayer insulating film (insulating film) having a two-layer structure including insulating layers 5 and 7 is formed. As such an interlayer insulating film, for example, insulating films 110 and 120 shown in FIGS. 1 and 2 can be used. In this case, the insulating layers 5 and 7 correspond to the A layer 111 or the B layer 112 and the B layer 112 or the A layer 111, respectively. Alternatively, each of the insulating layers 5 and 7 may be a composite film of the A layer 111 and the B layer 112, respectively.

(4) Side wall oxide films 4A and 4B are formed on the side wall of the gate electrode 3, and a field oxide film 2A is formed in a diffusion region 1B on the side of the gate electrode, thereby performing element isolation. In the vicinity of the gate electrode 3 in the insulating layer 5, a contact hole 5A in which an electrode 6 functioning as a bit line is embedded is formed. Further, a flattened insulating layer 7 is adhered on the flattened insulating layer 5, and a storage electrode 8A is buried in a contact hole 7A formed to penetrate both. The counter electrode 8C is provided on the storage electrode 8A via a capacitor insulating film 8B made of a high dielectric substance.

According to the electronic component such as the memory capacitor cell 8 having the insulating film of the present invention configured as described above, the relative permittivity of the insulating film is sufficiently reduced as compared with the related art, so that the wiring in the signal propagation is reduced. The delay time can be sufficiently reduced. In addition, since the film strength of the insulating film is sufficiently increased, delamination is prevented in a polishing step such as CMP in a manufacturing process of an electronic component such as the memory capacitor cell 8, and a reduction in product yield can be prevented. Device reliability can be improved.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Synthesis Example 1>
(Production of borazine-based resin composition 1)
0.1 g (0.50 mmol) of B, B ', B "-triethynyl-N, N', N" -trimethylborazine and 0.1 g (0.50 mmol) of p-bis (dimethylsilyl) benzene are dissolved in 8 ml of ethylbenzene. Then, 10 μl of a xylene solution of platinum divinyltetramethyldisiloxane (containing 2% of platinum) was added, and the mixture was stirred at room temperature under nitrogen for 3 days to obtain a borazine compound. When a part of the reaction solution was taken out and subjected to gas chromatography (GC) analysis, the peak of the monomer B, B ', B "-triethynyl-N, N', N" -trimethylborazine almost disappeared, Further, it was confirmed that the peak of p-bis (dimethylsilyl) benzene had disappeared.

FIG. 6 is a graph showing a gas chromatogram of the reaction solution immediately after the start of the polymerization, and FIG. 7 is a graph showing a gas chromatogram of the reaction solution after stirring for 3 days from the start of the polymerization. "A" in FIG. 6 is a peak corresponding to p-bis (dimethylsilyl) benzene, and "b" in FIGS. 6 and 7 is B, B ', B "-triethynyl-N, N', N". -A peak corresponding to trimethylborazine. The molecular weight (based on standard polystyrene) of the borazine-based resin composition 1 (containing a compound having a borazine skeleton) generated from GPC analysis was Mn = 4300 (Mw / Mn = 2.5). FIG. 8 is a graph showing a GPC chart of the obtained borazine-based resin composition 1.

<Synthesis Example 2>
(Production of borazine-based resin composition 2)
B, B ', B "-tris (1'-propynyl) -N, N', N" -trimethylborazine 3.6 g (15 mmol), 1,3,5,7-tetramethylcyclotetrasiloxane 3.6 g ( 15 mmol) was dissolved in 150 ml of mesitylene, 30 μl of a xylene solution of platinum divinyltetramethyldisiloxane (containing 2% of platinum) was added, and the mixture was stirred at 40 ° C. for 1 day under nitrogen. Thereto was added 30 μl of a xylene solution of platinum divinyltetramethyldisiloxane (containing 2% of platinum), and the mixture was stirred at 40 ° C. for 1 day under nitrogen. Subsequently, 0.36 g (1.5 mmol) of 1,3,5,7-tetramethylcyclotetrasiloxane was added, and the mixture was stirred at 40 ° C. for 1 day under nitrogen. A part of the reaction solution was taken out, and subjected to gas chromatography (GC) analysis. As a result, the monomer B, B ′, B ″ -tris (1′-propynyl) -N, N ′, N ″ -trimethylborazine was removed. It was confirmed that the peak of 1,3,5,7-tetramethylcyclotetrasiloxane had disappeared.

FIG. 9 is a graph showing a GPC chart of the obtained borazine-based resin composition 2 (containing a compound having a borazine skeleton). According to GPC analysis, the molecular weight (based on standard polystyrene) of the product was Mn = 11000 (Mw / Mn = 29).

<Example 1>
(Formation of insulating film 1)
First, SOG type low dielectric constant material HSG-R7 (manufactured by Hitachi Chemical Co., Ltd.) was spin-coated on a low resistivity silicon wafer (resistivity <10 Ωcm) at 2000 rpm / 30 seconds. After the application, the solvent is removed at 150 ° C for 1 minute in a nitrogen atmosphere, then at 250 ° C for 1 minute, and then the film is cured at 400 ° C for 30 minutes in a quartz tube furnace in which the O ₂ concentration is controlled to around 100 ppm. Thus, a layer B was formed.

Next, on the layer B, the borazine-based resin composition 1 obtained in Synthesis Example 1 was filtered with a filter, and the filtrate was spin-coated at 1000 rpm / 30 seconds. After heating this silicon wafer at 200 ° C. for 1 hour using a hot plate in a nitrogen atmosphere, using a quartz tube furnace in which the O ₂ concentration is controlled to about 100 ppm, 300 ° C./30 minutes, then 400 ° C. / The layer A was formed by baking for 30 minutes to obtain an insulating coating 1 having a two-layer structure similar to the insulating coating 120 shown in FIG.

<Example 2>
(Formation of insulating film 2)
An insulating film 2 having the same two-layer structure as the insulating film 110 shown in FIG. 1 was obtained in the same manner as in Example 1 except that the order of forming the A layer and the B layer was reversed.

<Example 3>
(Formation of insulating film 3)
First, an organic polymer type low dielectric constant material SiLK (manufactured by Dow Chemical Company) was spin-coated on a low resistivity silicon wafer (resistivity <10 Ωcm) at 2000 rpm / 20 seconds. After coating, the solvent is removed by heating at 70 ° C./20 seconds on a hot plate in a nitrogen atmosphere, and then 325 ° C./2 minutes in a quartz tube furnace in which the O ₂ concentration is controlled to about 100 ppm, followed by 450 ° C./2 minutes. The coating was cured to form a layer B.

Next, on the layer B, the borazine-based resin composition 1 obtained in Synthesis Example 1 was filtered with a filter, and the filtrate was spin-coated at 1000 rpm / 30 seconds. After heating this silicon wafer at 200 ° C. for 1 hour using a hot plate in a nitrogen atmosphere, using a quartz tube furnace in which the O ₂ concentration is controlled around 100 ppm, 300 ° C./30 minutes, then 400 ° C. / Baking was performed for 30 minutes to form an A layer, and an insulating coating 3 having a two-layer structure similar to the insulating coating 120 shown in FIG. 2 was obtained.

<Example 4>
(Formation of insulating film 4)
An insulating coating 4 having the same two-layer structure as the insulating coating 110 shown in FIG. 1 was obtained in the same manner as in Example 3, except that the order of forming the A layer and the B layer was reversed.

<Example 5>
(Formation of insulating film 5)
First, SOG type low dielectric constant material HSG-R7 (manufactured by Hitachi Chemical Co., Ltd.) was spin-coated on a low resistivity silicon wafer (resistivity <10 Ωcm) at 2000 rpm / 30 seconds. After the application, the solvent is removed at 150 ° C for 1 minute in a nitrogen atmosphere, then at 250 ° C for 1 minute, and then the film is cured at 400 ° C for 30 minutes in a quartz tube furnace in which the O ₂ concentration is controlled to about 100 ppm. Thus, a layer B was formed.

Next, on the layer B, the borazine-based resin composition 2 obtained in Synthesis Example 2 was filtered with a filter, and the filtrate was spin-coated at 1000 rpm / 30 seconds. After heating this silicon wafer at 200 ° C. for 1 hour using a hot plate in a nitrogen atmosphere, using a quartz tube furnace in which the O ₂ concentration is controlled around 100 ppm, 300 ° C./30 minutes, then 400 ° C. / The layer A was formed by baking for 30 minutes to obtain an insulating film 5 having the same two-layer structure as the insulating film 120 shown in FIG.

<Example 6>
(Formation of insulating film 6)
An insulating film 6 having the same two-layer structure as the insulating film 110 shown in FIG. 1 was obtained in the same manner as in Example 5, except that the order of forming the A layer and the B layer was reversed.

<Example 7>
(Formation of insulating film 7)
First, an organic polymer type low dielectric constant material SiLK (manufactured by Dow Chemical Company) was spin-coated on a low resistivity silicon wafer (resistivity <10 Ωcm) at 2000 rpm / 20 seconds. After coating, the solvent is removed by heating at 70 ° C./20 seconds on a hot plate in a nitrogen atmosphere, and then 325 ° C./2 minutes in a quartz tube furnace in which the O ₂ concentration is controlled to about 100 ppm, followed by 450 ° C./2 minutes. The coating was cured to form a layer B.

Next, on this B layer, the borazine-based resin 2 obtained in Synthesis Example 2 was filtered with a filter, and the filtrate was spin-coated at 1000 rpm / 30 seconds. After heating this silicon wafer at 200 ° C. for 1 hour using a hot plate in a nitrogen atmosphere, using a quartz tube furnace in which the O ₂ concentration is controlled around 100 ppm, 300 ° C./30 minutes, then 400 ° C. / The layer A was formed by baking for 30 minutes to obtain an insulating film 7 having the same two-layer structure as the insulating film 120 shown in FIG.

<Example 8>
(Formation of insulating film 8)
An insulating coating 8 having the same two-layer structure as the insulating coating 110 shown in FIG. 1 was obtained in the same manner as in Example 7, except that the order of forming the A layer and the B layer was reversed.

<Comparative Example 1>
(Formation of insulating film 9)
1 ml of HSG-R7 (concentration of about 40%) manufactured by Hitachi Chemical Co., Ltd. and 8 ml of borazine-based resin composition 1 (concentration of about 3%) obtained in Synthesis Example 1 were mixed, and the mixture was filtered through a filter. Spin coating was performed on a silicon wafer (resistivity <10 Ωcm) at 1500 rpm / 30 seconds. Next, the silicon wafer was heated at 200 ° C. for 1 hour using a hot plate in a nitrogen atmosphere, and then, at 300 ° C. for 30 minutes, and then at 400 ° C. for 30 minutes using a quartz tube furnace in which the O 2 concentration was controlled to around 100 ppm. After baking for minutes, an insulating coating layer 9 was obtained.

<Relative permittivity measurement>
The relative dielectric constants of the insulating coatings 1 to 9 obtained in Examples 1 to 8 and Comparative Example 1 were measured. Here, the “relative dielectric constant” of the insulating film in the present invention refers to a value measured in an atmosphere of 23 ° C. ± 2 ° C. and a humidity of 40 ± 10%, and is composed of an Al metal and an N-type low resistivity substrate (Si). It is determined from the measurement of the charge capacity between wafers.

Specifically, after each of the insulating coatings 1 to 9 are formed, Al metal is vacuum-deposited on the insulating coatings in a vacuum evaporation apparatus so as to be a circle having a diameter of 2 mm and a thickness of about 0.1 μm. As a result, a structure in which the insulating coating is disposed between the Al metal and the low resistivity substrate is formed. Next, the charge capacity of this structure was measured at an operating frequency of 1 MHz using a device in which a dielectric test fixture (HP16451B, manufactured by Yokogawa Electric) was connected to an LF impedance analyzer (HP4192A, manufactured by Yokogawa Electric). It was measured.

Then, the measured value of the charge capacity is calculated by the following equation;
Relative dielectric constant of insulating film = 3.597 × 10 ⁻² × charge capacity (pF) × film thickness of insulating film (μm);
And the relative dielectric constant of the insulating film was calculated. As the thickness of the insulating film, a value measured by an ellipsometer L116B manufactured by Gartner was used.

<Young's modulus measurement>
For each of the insulating coatings, the Young's modulus was measured as an index of the film strength using a nano indenter DCM manufactured by MTS.

Table 1 shows the measurement results of the film thickness, the relative dielectric constant, and the Young's modulus of the insulating coatings 1 to 9.

As shown in Table 1, the insulating coatings 1 to 8 (Examples 1 to 8) in which the A layers and the B layers are alternately laminated have the relative dielectric constants formed by using a mixed solution of a borazine compound and a non-borazine compound. It was confirmed that it was significantly reduced as compared with the coating 9 (Comparative Example 1), and that the Young's modulus was improved in each step. It is presumed that the borazine compound in the mixed solution was hydrolyzed in the insulating coating 5.

FIG. 2 is a schematic cross-sectional view illustrating a configuration example of an insulating film according to the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration example of an insulating film according to the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration example of an insulating film according to the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration example of an insulating film according to the present invention. FIG. 1 is a schematic sectional view showing a preferred embodiment of an electronic component according to the present invention. 4 is a graph showing a gas chromatogram of a reaction solution immediately after the start of polymerization in Synthesis Example 1. 4 is a graph showing a gas chromatogram of a reaction solution after stirring for 3 days from the start of polymerization in Synthesis Example 1. 4 is a graph showing a GPC chart of the polymer obtained in Synthesis Example 1. 6 is a graph showing a GPC chart of a polymer obtained in Synthesis Example 2.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Silicon wafer (substrate), 1A, 1B ... Diffusion area, 2A ... Field oxide film, 2B ... Gate insulating film, 3 ... Gate electrode, 4A, 4B ... Side wall oxide film, 5, 7 ... Insulating layer (insulating coating) 5A, 7A contact hole, 6 bit line, 8 memory cell capacitor (electronic component), 8A storage electrode, 8B capacitor insulating film, 8C counter electrode, 110, 120, 130, 140 insulating coating, 111 ... A layer (first insulating layer), 112 ... B layer (second insulating layer), a ... peak corresponding to p-bis (dimethylsilyl) benzene, b ... B, B ', B "-triethynyl Peak corresponding to -N, N ', N "-trimethylborazine.

Claims (3)

Insulating coating formed by alternately stacking at least one first insulating layer containing a compound having a borazine skeleton in a molecular structure and at least one second insulating layer different from the first insulating layer . The compound having a borazine skeleton in the molecular structure is represented by the following formula (1);

(Wherein, R ¹ represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom, R ² represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom, and R ³ and R ⁴ represent an alkyl group, an aryl group, R ⁵ represents the same or different monovalent group selected from an aralkyl group and a hydrogen atom; R ⁵ represents a substituted or unsubstituted aromatic divalent group, an oxypoly (dimethylsiloxy) group, or an oxygen atom; ⁶ represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom, a represents a positive integer, b represents 0 or a positive integer, p represents 0 or a positive integer, q represents 0 or a positive integer. Indicates an integer.),
Having a repeating unit represented by
The insulating coating according to claim 1. An electronic component comprising the insulating coating according to claim 1 provided on a base.

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