JP6042151B2 - Insulating material for semiconductor containing silica particles - Google Patents

Description

  The present invention relates to a semiconductor insulating material containing silica particles, and the like.

  In recent years, in order to increase the degree of integration of memory cells, many semiconductor memory devices in which memory cells are arranged three-dimensionally have been proposed. In such a semiconductor device, it is necessary to perform electrical isolation between the memory cells and between the circuit elements by forming a trench in a portion corresponding to a gap between the memory cell and the circuit element and embedding an insulating material in the trench. . As such an insulating material for filling a trench, silicon oxide is widely and preferably used because of its high insulating properties.

  As a means for embedding silicon oxide in the trench, there is a conventional CVD (chemical vapor deposition) method, and a silicon oxide film can be formed on a substrate having a trench. On the other hand, as a method other than CVD, a method of forming a silicon oxide by embedding a liquid material in a trench by a coating method and baking it in an oxidizing atmosphere is known. As liquid materials used in this method, polysilazane materials (for example, Patent Document 1), polysilane materials (for example, Patent Document 2), and silicone materials are known.

  In particular, since a silicone material is accompanied by dehydration and dealcohol condensation reactions when forming a coating film, voids and cracks are likely to occur in the obtained silicon oxide film. In addition, when the silicone material is converted into the silicon oxide film, there is a problem that the density becomes non-uniform from the film surface toward the bottom of the trench because of significant curing shrinkage.

  As a method for avoiding the occurrence of such voids and cracks, a composition containing silica particles and a polysiloxane compound has been proposed (for example, Patent Document 3). Patent Documents 4 to 7 describe materials obtained by condensation reaction of silica particles and a polysiloxane compound as materials designed for use as an interlayer insulating film.

  Further, Patent Documents 8 and 9 describe that a composition containing a polysiloxane compound and silica particles is a material having a low cure shrinkage ratio and a high resistance to HF when fired into a silicon oxide film after coating. ing.

JP 2001-308090 A JP 2003-31568 A JP 2006-310448 A JP-A-5-263045 Japanese Patent Laid-Open No. 4-10418 JP-A-3-263476 Japanese Patent No. 4746704 JP 2010-153655 A JP 2011-26570 A

  As semiconductor devices and the like are highly integrated and multi-layered, materials that exhibit better electrical characteristics are required to electrically isolate memory cells and circuit elements. The above-described excellent electrical characteristics are low leakage current. That is, an object of the present invention is to provide a semiconductor insulating material with a small leakage current.

  As a result of intensive studies to develop a method for achieving the above object, the present inventors have found that an insulating material containing silica particles in a specific state reduces leakage current as shown below. Completed. That is, the present invention is as follows.

[1] A semiconductor insulating material containing a silicon atom, a carbon atom, and an oxygen atom,
Containing silica particles in a volume proportion of greater than 9.5% and not greater than 30%;
When the composition ratio (C / Si) of carbon atoms to silicon atoms is larger than 0 and smaller than 0.85, and the scattering vector q is 0.1 nm ^{−1 in} the small angle incident X-ray small angle scattering (GI-SAXS) measurement The ratio (I ₁ (q) / I ₂ (q)) of the scattering intensity I ₁ (q) to the scattering intensity I ₂ (q) when the scattering vector q is 0.2 nm ⁻¹ is 1.35. An insulating material for semiconductor, which is the following.
[2] The semiconductor insulating material according to [1], wherein the composition ratio (C / Si) of the carbon atom to the silicon atom is 0.54 or more and 0.62 or less.
[3] The semiconductor insulating material according to the above [1] or [2], wherein a volume ratio of the silica particles is 13% or more and 20% or less.
[4] A method for producing an insulating material for a semiconductor according to any one of [1] to [3],
Applying a material composition containing a polysiloxane compound and silica particles to a substrate, and baking and curing the material composition;
The polysiloxane compound has the following general formula (1):
R ¹ Si (OR ² ) ₃ (1)
(Wherein R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, and R ² is each independently a hydrocarbon group having 1 to 6 carbon atoms.)
One or more silane monomers represented by the following general formula (2):
Si (OR ³ ) ₄ (2)
(In the formula, each R ³ is independently a hydrocarbon group having 1 to 6 carbon atoms.)
The manufacturing method of the insulating material for semiconductors obtained by carrying out hydrolysis polycondensation of the silane component which contains the 1 or more types of silane monomer represented by these in the quantity of 50 mass% or more in total.
[5] The semiconductor insulating material according to [4], wherein the material composition includes 20 parts by mass or more and 30 parts by mass or less of the silica particles with respect to 100 parts by mass in total of the polysiloxane compound and the silica particles. Manufacturing method.

  According to the present invention, it is possible to provide a semiconductor insulating material containing silica particles that can reduce leakage current.

It is a figure which shows the GI-SAXS measurement result of Example 1 and Comparative Example 1. Scattering vector in GI-SAXS measurement is an enlarged view of the range of 0.25 nm ^-1 from 0.05 nm ^-1. It is a figure which shows the GI-SAXS measurement result of Example 1, and the fitting result when the particle volume ratio is 13% in the hard sphere model. It is a figure which shows the measurement result of the IV characteristic of Example 1 and Comparative Example 1.

  Hereinafter, modes for carrying out the present invention (hereinafter abbreviated as “embodiments”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

The insulating material for a semiconductor of the present invention (hereinafter sometimes referred to simply as an insulating material) contains a carbon atom, a silicon atom, and an oxygen atom, and typically comprises a carbon atom, a silicon atom, an oxygen atom, and an unavoidable impurity. The insulating material contains silica particles and satisfies the following characteristics (1), (2) and (3).
(1) The composition ratio (C / Si) of carbon atoms to silicon atoms (also referred to as C / Si ratio in the present disclosure) (atomic number ratio) is greater than 0 and less than 0.85.
(2) The volume fraction of silica particles is greater than 9.5% and not greater than 30%.
(3) In small-angle incident X-ray small angle scattering (GI-SAXS), the scattering intensity I ₁ (q) when the scattering vector q is 0.1 nm ⁻¹ and the scattering vector q when the scattering vector q is 0.2 nm ⁻¹ The ratio (I ₁ (q) / I ₂ (q)) to the scattering intensity I ₂ (q) is 1.35 or less.

<Regarding (3)>
Insulating material of the present invention in Grazing Incidence X-ray small angle scattering (GI-SAXS), the scattering intensity when the scattering vector q is 0.1nm ^-1 I ₁ (q), the scattering vector q is 0.2 nm ^-1 The ratio (I ₁ (q) / I ₂ (q)) to the scattering intensity I ₂ (q) at this time is 1.35 or less. Here, the scattering vector q is q = 4π sin θ / λ, 2θ is the scattering angle, and λ is the wavelength of the incident X-ray. The scattering intensity I (q) is related to the fluctuation of the electron density in the scattering volume, and the nanoscale periodic structure and the shape and size of the scatterer can be known from I (q). The insulating material of the present invention contains carbon atoms, silicon atoms, and oxygen atoms, and contains silica particles. Accordingly, in the insulating material, the silica particles (that is, the portion composed of silicon atoms and oxygen atoms) and the portion other than the silica particles (that is, the portion including at least carbon atoms) have an electron density difference. For example, the insulating material can be manufactured using a silicon compound containing an organic group (for example, a polysiloxane compound described later). In this case, the portion other than the silica particles contains carbon derived from the organic group, and the silica particle portion And portions other than the silica particles have a significant difference in electron density. Therefore, it is considered that most of the scattering observed with GI-SAXS is derived from the particle size of the silica particles and the distribution state (ie, arrangement) of the particles. As described above, in the present embodiment, the presence state of silica particles is evaluated by GI-SAXS measurement.

Information on the degree of aggregation of silica particles can be obtained from measurement of a small-angle region of 0.5 nm ⁻¹ or less in GI-SAXS measurement. When the silica particle in the material is regarded as a hard sphere and the analysis is performed with a model assuming that the silica particle exists uniformly in the material, the small angle of the scattering vector q from 0.1 nm ⁻¹ to 0.2 nm ⁻¹ The change in the scattering intensity I (q) in the region is small. In fact, the scattering intensity when the scattering vector q is 0.1 nm ^-1 I ₁ of (q), the ratio of scattering intensity I ₂ (q) when the said q is _{^{0.2nm -1 (I 1 (q)}} / I ₂ (q)) is 1.35 or less. That is, when the measurement result of a certain material containing silica particles is close to this model, it can be considered that the silica particles are uniformly present in the material and no aggregation occurs. On the other hand, when the scattering intensity I ₁ (q) when the scattering vector q is 0.1 nm ⁻¹ is much larger than the scattering intensity I ₂ (q) when q is 0.2 nm ⁻¹ , silica It can be considered that the particles are not uniformly present in the material, that is, aggregation occurs due to the interaction between the particles.

Inventors, the scattering intensity when the scattering vector q is 0.1 nm ^-1 I ₁ of (q), the ratio of scattering intensity I ₂ (q) when the said q is 0.2nm ^-1 (I ₁ (q It was found that the leakage current increases dramatically when the insulating material does not satisfy the condition that) / I ₂ (q)) is 1.35 or less. Probably, the aggregation of silica particles becomes prominent, and this is a defect in the insulating material. As a result, leakage current is likely to occur. From the above, the insulating material of the present embodiment, the scattering intensity when the scattering vector q is 0.1 nm ^-1 I ₁ of (q), the scattering intensity I ₂ (q when the said q is 0.2 nm ^-1 ) (I ₁ (q) / I ₂ (q)) must be 1.35 or less.

Further, from the viewpoint of suppressing aggregation of silica particles, I ₁ (q) / I ₂ (q) described above is more preferably 1.30 or less, and still more preferably 1.20 or less. The I ₁ (q) / I ₂ (q) ratio is preferably as small as possible from the viewpoint of suppressing the aggregation of silica particles, but is preferably 0 from the viewpoint of being close to a model in which the particles are uniformly present in the film. More preferably, it can be 0.25 or more, more preferably 0.50 or more.

  In the GI-SAXS measurement in the present invention, a two-dimensional detector is used. The use of a two-dimensional detector is advantageous in time division measurement and grasping of anisotropy. However, since the two-dimensional detector measures all air scattering generated in the beam path, measurement in a vacuum or helium gas is necessary.

In the above measurement, only the scattering within the sample surface is taken out from the two-dimensional GI-SAXS pattern and is made one-dimensional. As a result, the scattering intensity in the small-angle region can be accurately measured, and the scattering intensity ratio (I ₁ (q) / I ₂ (q)) in the present invention can be appropriately calculated.

  The insulating material is more typically, but not limited to, for example, onto a substrate of a material composition containing silica particles under conditions of a temperature of 20 ° C. to 25 ° C. and a relative humidity of 40% to 50%. And subsequent baking in a baking furnace. More typically, the insulating material is made under the conditions described in the examples below.

An insulating material satisfying the specific I ₁ (q) / I ₂ (q) ratio as described above can be formed by polycondensation of silica particles and a polysiloxane compound and baking and curing the resulting material composition. At that time, it is important to set the volume ratio of the silica particles in the insulating material to a predetermined value or less. Details will be described later.

<Regarding (1)>
With respect to conventional materials designed for insulating films for semiconductor applications, insulating materials formed using a material composition containing polysiloxane containing organic groups are difficult only with SiO ₂ which is a general insulating material. It exhibits crack resistance, low shrinkage, and hydrophobicity. Since these characteristics can largely depend on the carbon / silicon composition ratio in the insulating material, the determination of the carbon / silicon composition ratio is extremely important.

  The insulating material of the present invention is characterized in that the C / Si ratio is larger than 0 and smaller than 0.85. When the C / Si ratio is larger than 0, it is advantageous in that the hydrophobicity of the film is increased and the leakage current due to adsorbed water is reduced. The C / Si ratio is preferably 0.28 or more, more preferably 0.54 or more. On the other hand, when the C / Si ratio is less than 0.85, it is advantageous from the viewpoint of suppressing aggregation of silica particles and reducing leakage current. The C / Si ratio is preferably 0.75 or less, more preferably 0.62 or less. The C / Si ratio can be measured by X-ray photoelectron spectroscopy (XPS). The XPS measurement in the present invention may be performed using a conventionally known method and apparatus. In measuring the C / Si ratio, other measurement methods such as Rutherford backscattering analysis (RBS) and nuclear reaction analysis (NRA) may be used. It is sufficient that the C / Si ratio is obtained.

  The insulating material is more typically, but not limited to, for example, onto a substrate of a material composition containing silica particles under conditions of a temperature of 20 ° C. to 25 ° C. and a relative humidity of 40% to 50%. And subsequent baking in a baking furnace. More typically, the insulating material is made under the conditions described in the examples below.

  The insulating material satisfying the specific C / Si ratio as described above can be formed by polycondensing silica particles and a polysiloxane compound, and baking and curing the resulting material composition. At that time, the ratio of the polysiloxane compound and the silica particles in the material composition, the carbon number of the organic group in the polysiloxane compound (for example, the hydrocarbon in the silane monomer represented by the following general formulas (1) and (2)) It is important to select the number of carbon groups.

<Regarding (2)>
The insulating material of the present invention is characterized in that the volume ratio of the silica particles is larger than 9.5% and not more than 30%, assuming that the total volume ratio of the silica particles and other components in the material is 100%. . Information on the distribution state of the silica particles, that is, the volume ratio of the silica particles in the insulating material can be obtained from the measurement in the wide-angle region of 0.5 nm ⁻¹ or more in the above-described GI-SAXS measurement. The volume ratio of the silica particles of the present disclosure is defined as follows. That is, the scattering intensity profile in the wide-angle region where the scattering vector (q) in the SAXS measurement is 0.5 nm ⁻¹ or more is fitted with the scattering intensity profiles based on various silica particle volume ratio models when the silica particles are assumed to be hard spheres. Then, the silica particle volume ratio of the model profile that matches the actual measurement profile is defined as the volume ratio of the silica particles of the present disclosure.
The volume ratio of silica particles being larger than 9.5% is advantageous in terms of reducing leakage current. The volume ratio is preferably 11% or more, more preferably 13% or more. On the other hand, the volume ratio of 30% or less is advantageous in that the aggregation of silica particles is suppressed and the leakage current is reduced. The volume ratio is preferably 25% or less, more preferably 20% or less.

  Examples of the silica particles include fumed silica and colloidal silica. The fumed silica can be obtained by reacting a compound containing a silicon atom with oxygen and hydrogen in a gas phase. Examples of the silicon compound used as a raw material include silicon halide (for example, silicon chloride).

  The colloidal silica can be synthesized by a sol-gel method in which a raw material compound is hydrolyzed and condensed. Examples of the raw material for colloidal silica include alkoxy silicon (for example, tetraethoxysilane) and halogenated silane compounds (for example, diphenyldichlorosilane). Among these, colloidal silica obtained from alkoxy silicon is preferable from the viewpoint that impurities such as metal ions and halogens are not mixed.

  The average primary particle diameter of the silica particles is preferably 1 nm to 120 nm, more preferably 1 nm to 40 nm, still more preferably 1 nm to 20 nm, and most preferably 1 nm to 15 nm. When the average primary particle size is 1 nm or more, the crack resistance is good, and when it is 120 nm or less, the embedding property in the trench is good.

  The average secondary particle diameter of the silica particles is preferably 2 nm to 250 nm, more preferably 2 nm to 80 nm, still more preferably 2 nm to 40 nm, and most preferably 2 nm to 30 nm. When the average secondary particle size is 2 nm or more, the crack resistance is good, and when it is 250 nm or less, the embedding property in the trench is good.

  The average primary particle diameter is determined by a specific surface area (BET method) calculated from the pressure and adsorption amount of nitrogen molecules. The average secondary particle diameter is measured with a dynamic light scattering photometer.

The insulating material satisfying the above features (1) to (3) is typically an insulating material containing silica particles and silicon oxide, and the silicon oxide is obtained by firing a polysiloxane compound. It is what
In a preferred embodiment, the polysiloxane compound has the following general formula (1):
R ¹ Si (OR ² ) ₃ (1)
(Wherein R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, and R ² is each independently a hydrocarbon group having 1 to 6 carbon atoms.)
One or more silane monomers represented by the following general formula (2):
Si (OR ³ ) ₄ (2)
(In the formula, each R ³ is independently a hydrocarbon group having 1 to 6 carbon atoms.)
It is obtained by hydrolytic polycondensation of a silane component containing one or more silane monomers represented by the formulas in a total amount of preferably 50% by mass or more.

The portion other than the silica particles of the insulating material preferably contains 10% or more, more preferably 15% or more, still more preferably 20% or more, and preferably 35% or less, more preferably 30% of carbon atoms based on the number of atoms. % Or less, more preferably 25% or less.
The portion other than the silica particles of the insulating material preferably contains silicon atoms on the basis of the number of atoms, preferably 15% or more, more preferably 20% or more, still more preferably 25% or more, and preferably 45% or less, more preferably 40%. % Or less, more preferably 35% or less.
The portion other than the silica particles of the insulating material preferably has an oxygen atom of 35% or more, more preferably 40% or more, still more preferably 45% or more, and preferably 60% or less, more preferably 55, based on the number of atoms. % Or less, more preferably 50% or less.
These contents are values calculated by excluding the contribution of the volume fraction of silica particles (SiO ₂ ) from the ratio of the number of carbon, silicon, and oxygen elements obtained by XPS measurement of the insulating material.

<Insulating material manufacturing method>
The present embodiment also provides an insulating material manufacturing method including a coating step of applying a material composition containing silica particles to a substrate to obtain a coated substrate, and a baking step of heating the coated substrate obtained in the coating step. provide.
A preferred embodiment is a method for producing an insulating material for a semiconductor,
Applying a material composition comprising a polysiloxane compound and silica particles to a substrate and baking and curing the material composition;
The polysiloxane compound has the following general formula (1):
R ¹ Si (OR ² ) ₃ (1)
(Wherein R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, and R ² is each independently a hydrocarbon group having 1 to 6 carbon atoms.)
One or more silane monomers represented by the following general formula (2):
Si (OR ³ ) ₄ (2)
(In the formula, each R ³ is independently a hydrocarbon group having 1 to 6 carbon atoms.)
The manufacturing method of the insulating material for semiconductors obtained by carrying out the hydrolysis polycondensation of the silane component which contains the 1 or more types of silane monomer represented by these in the quantity of 50 mass% or more in total is provided.

  The material composition containing silica particles can be applied onto the substrate by a usual method. Examples of the coating method include spin coating, dip coating, roller blade coating, and spray coating. Among these, the spin coating method is preferable from the viewpoint that the thickness of the coating film during film formation is uniform.

  An example of the substrate is a silicon substrate. A substrate having a trench structure can be used. For example, when a material composition is applied to a silicon substrate having a trench structure by a spin coating method, it may be applied at a single rotation speed or a combination of multiple rotation speeds. It is preferable to set the rotational speed of at least the first stage to a low speed and to increase the speed of the second and subsequent stages. By rotating at a low speed in the first stage, the material composition can be spread over the entire surface of the silicon substrate, and the embedding property is improved. Further, the number of times of application of the material composition may be one or more, but it is preferable to apply the material composition at a time from the viewpoint of good film formability and a reduction in manufacturing cost.

  In the coating step, the solid content concentration of the material composition to be coated on the substrate is not particularly limited, and can be carried out at any solid content concentration according to the target film thickness of the coating film.

  Although there is no restriction | limiting in particular about the temperature and time of the said application | coating process, It is preferable that temperature is 0 to 100 degreeC, More preferably, it is 20 to 80 degreeC, Time is 0.1 to 30 minutes. It is preferably not more than minutes, more preferably not less than 0.2 minutes and not more than 10 minutes.

  Next, the coated substrate is heated in the firing step. In the above coating step, it is preferable to pre-cure (pre-bake) the material composition in a range of 50 ° C. to 200 ° C. after removing the residual solvent in the coating film after coating the material composition on the substrate. At this time, the temperature may be raised stepwise or continuously. The atmosphere at the time of pre-curing (pre-baking) may be an oxidizing atmosphere containing an oxidizing gas such as oxygen or water vapor, or a non-oxidizing atmosphere substantially not containing an oxidizing gas.

  Next, a cured film can be obtained by heating and baking a film obtained by optionally pre-curing (pre-baking). As a heating and baking method, for example, a general heating means such as a hot plate, an oven, or a furnace can be applied. Heating and baking are preferably performed in a non-oxidizing atmosphere. The heating and baking temperature is preferably 200 ° C. or higher and 900 ° C. or lower, more preferably 300 ° C. or higher and 800 ° C. or lower, and further preferably 350 ° C. or higher and 750 ° C. or lower. If the heating and baking temperature is 200 ° C. or higher, the obtained film quality is good, and if it is 900 ° C. or lower, the crack resistance is good.

  Examples of the non-oxidizing atmosphere include a vacuum or an inert atmosphere such as nitrogen, helium, argon, or xenon. The concentration of an oxidizing gas such as oxygen or water vapor contained in these inert atmospheres is preferably 1000 ppm or less, more preferably 100 ppm or less, and further preferably 10 ppm or less. There is no restriction | limiting in particular about the pressure of a non-oxidizing atmosphere, Any of pressurization, a normal pressure, or pressure reduction may be sufficient.

  In the baking step, it is preferable to perform heat baking in a gas containing hydrogen in a high temperature region of 700 ° C. or higher and 900 ° C. or lower. The gas containing hydrogen used in the firing process may be introduced from the beginning of the firing process, that is, from the time when the substrate temperature is lower than 700 ° C., or may be introduced after reaching 700 ° C. Furthermore, after performing the first heating with a gas not containing hydrogen at a temperature of 700 ° C. or more and 900 ° C. or less, the heating and firing are performed in two stages, in which a gas containing hydrogen is introduced and the second heating is performed. Also good. In any method, it is preferable to keep introducing a gas containing hydrogen until the substrate after heating and baking is cooled to a temperature of 400 ° C. or lower, preferably about room temperature.

  As described above, performing the firing step in a gas containing hydrogen is particularly advantageous when the silane represented by the general formula (1) and the silane represented by the general formula (2) are used. . That is, in this case, even if the chemical bond between the silicon atom and the organic group is broken at a high temperature exceeding 700 ° C., the generated dangling bond can be terminated with hydrogen, thereby preventing the formation of a silanol group, It is possible to realize good film properties as an insulating material of a semiconductor element.

  The heat treatment time in the firing step is preferably 1 minute to 24 hours, and more preferably 30 minutes to 12 hours.

  In the firing step, heat firing in an oxidizing atmosphere and light treatment may be used in combination. The temperature when heating and light treatment are performed simultaneously is preferably 20 ° C. or more and 600 ° C. or less, and the treatment time is preferably 0.1 minutes or more and 120 minutes or less. For the light treatment, for example, visible light, ultraviolet light, deep ultraviolet light, or the like can be used. As a light source for light treatment, for example, a low-pressure or high-pressure mercury lamp, deuterium lamp, or discharge light of a rare gas such as argon, krypton, or xenon, YAG laser, argon laser, carbon dioxide gas laser, or XeF, XeCl, XeBr Excimer lasers such as KrF, KrCl, ArF or ArCl can be used. The output of these light sources is preferably 10 to 5,000 W.

The light wavelength of these light sources may be absorbed as much as possible by the film of the material composition containing silica particles formed on the substrate, and is preferably 170 nm or more and 600 nm or less. In light treatment, a light irradiation amount is preferably at 0.1 J / cm ² or more 1,000 J / cm ² or less, more preferably 1 J / cm ² or more 100 J / cm ² or less. Moreover, ozone may be generated simultaneously with the light treatment. By performing the light treatment under the conditions described above, the oxidation reaction of the material composition containing silica particles proceeds in the film formed on the substrate, and the film quality after baking can be improved.

  When the material composition includes a polysiloxane compound, the surface of the insulating material may be exposed to a hydrophobizing agent after the baking step. By exposing the cured film to a hydrophobizing agent, the silanol groups in the cured film react with the hydrophobizing agent, and the surface of the cured film can be hydrophobized.

<Manufacture of material composition containing silica particles>
A preferred method for producing a material composition containing silica particles will be described below.
The material composition containing silica particles in the present invention is preferably the following general formula (1):
R ¹ Si (OR ² ) ₃ (1)
(Wherein R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, and R ² is each independently a hydrocarbon group having 1 to 6 carbon atoms.)
One or more silane monomers represented by the following general formula (2):
Si (OR ³ ) ₄ (2)
(In the formula, each R ³ is independently a hydrocarbon group having 1 to 6 carbon atoms.)
It is a composition containing the polysiloxane compound obtained by carrying out hydrolysis polycondensation of the silane component containing 1 or more types of silane monomers represented by these, and a silica particle.

In the general formula (1), R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, and acyclic and cyclic saturated aliphatic hydrocarbon groups, aromatic hydrocarbon groups, acyclic and cyclic groups. Examples thereof include an unsaturated aliphatic hydrocarbon group, and a combination of two or more of these (for example, an arylalkyl group).

Among these, R ¹ is preferably a methyl group or an ethyl group from the viewpoint of providing a polysiloxane compound having a small weight loss upon conversion to silicon oxide during firing and having a small shrinkage rate. More preferably, it is a methyl group.

In the general formulas (1) and (2), R ² and R ³ are each independently a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a t-butyl group, an n-hexyl group, and a cyclohexyl group.

Among these, from the viewpoint of easy reactivity control, R ² and R ³ are each preferably a methyl group or an ethyl group.

  The polysiloxane compound only needs to be obtained by hydrolytic polycondensation of silane components each containing one or more of the silane monomer (1) and the silane monomer (2). A combination of several silane monomers is used. May be. The combination of silane monomers to be used can be selected according to the physical properties of the target polysiloxane compound. In general, by using a silane monomer having a small number of functional groups, a polysiloxane compound having a high degree of polymerization and excellent toughness can be obtained, and by using a silane monomer having a large number of functional groups, a dense and high mechanical strength polysiloxane compound. Is obtained.

  From such a viewpoint, as the insulating material used for the semiconductor element, in addition to the silane monomer represented by the general formula (1), the silane monomer represented by the general formula (2) is appropriately used in combination. preferable.

  The mixing ratio of the silane monomer represented by the general formula (1) (hereinafter also referred to as silane monomer (1)) and the silane monomer represented by the general formula (2) (hereinafter also referred to as silane monomer (2)) is The molar ratio is 0/100 to 100/0. From the viewpoint of crack resistance, the silane monomer (1) / silane monomer (2) (molar ratio) is 30/70 to 90/10. Preferably there is. More preferably, the molar ratio is 50/50 to 85/15, and more preferably 70/30 to 80/20. The silane component may or may not contain a monomer other than the silane monomer (1) and the silane monomer (2), and typically does not contain it.

  In the silane component, the total content of the silane monomer (1) and the silane monomer (2) is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably from the viewpoint of obtaining good crack resistance. 90% by mass or more, and most typically 100% by mass.

The molar ratio in the polysiloxane compound can be confirmed using, for example, ¹ H-NMR and ²⁹ Si-NMR.

  The polysiloxane compound can be produced by hydrolytic polycondensation of the silane component using a conventionally known method. A typical technique for hydrolysis polycondensation is a technique of reacting a silane component in the presence of an acid catalyst and water.

The content of silica particles in the material composition containing silica particles is preferably 16 parts by mass or more and 34 parts by mass or less, more preferably 20 parts by mass with respect to 100 parts by mass in total of the polysiloxane compound and the silica particles. The amount is 30 parts by mass or less. From the viewpoint of reducing the leakage current, the content of the silica particles is preferably 16 parts by mass or more. Moreover, it is preferable that the said content rate is 34 mass parts or less from a viewpoint of suppressing aggregation of the silica particle in a material composition. In the present disclosure, the amount of the polysiloxane compound when the total of the polysiloxane compound and the silica particles is 100 parts by mass is the amount in terms of condensation (that is, the hydrolyzable group remaining in the polysiloxane compound (specifically, Are used in such a manner that OR ² in the general formula (1) and OR ³ in the general formula (2) are each replaced with 1/2 O.

  In the material composition, the silica particles may exist in a state of being simply mixed with the polysiloxane compound, or may be present in a state of being condensed with the polysiloxane compound (condensation in which the polysiloxane compound and the silica particles are condensed). Component). When the material composition contains a condensation reaction product of the silica particles and the polysiloxane compound, an insulating material with particularly good crack resistance can be formed.

Examples of a method for producing a condensation reaction product of a polysiloxane compound and silica particles include the following methods.
(I) A polysiloxane compound is produced by hydrolytic polycondensation reaction of the silane component including the silane monomer (1) and the silane monomer (2), and then the silica particles and the obtained polysiloxane compound are further subjected to a condensation reaction. How to make.
(Ii) A method in which silica particles are allowed to coexist when the silane component containing the silane monomer (1) and the silane monomer (2) is subjected to a hydrolysis polycondensation reaction.
(Iii) A method in which silica particles are added to the reaction system during the hydrolysis polycondensation reaction of the silane component containing the silane monomer (1) and the silane monomer (2).

  When the silica particles are reacted with the polysiloxane compound or the silane component, a material dispersed in a solvent can be reacted. As a solvent to be used, water, an organic solvent, or a mixed solvent thereof can be used. As the organic solvent used, water, an organic solvent, or a mixed solvent thereof can be used. The organic solvent used varies depending on the dispersion medium of the silica particles used. When the silica particle dispersion medium used is aqueous, the reaction between the polysiloxane compound or the silane component and the silica particles may be carried out after adding water or an alcohol solvent to the silica particle aqueous dispersion medium. The aqueous solution of the particles may be replaced with an alcohol solvent once, and then the reaction between the polysiloxane compound or the silane component and the silica particles may be performed. Examples of the alcohol solvent that can be used include methanol, ethanol, n-propanol, 2-propanol, n-butanol, methoxyethanol, ethoxyethanol, and the like, and these are preferable because they are easily mixed with water.

  There is no restriction | limiting in particular in the reaction temperature at the time of making a silica particle react with a polysiloxane compound or a silane component, Usually, it carries out in 50 to 200 degreeC.

  The material composition may contain components other than the polysiloxane compound, silica particles and their condensation reaction products, for example, additives such as nitrogen-containing compounds, solvents, and the like. As the additive, an additive suitable for the purpose can be arbitrarily selected. The amount of the additive used is preferably within a range in which the additive exhibits an effect and does not affect other physical properties of the material composition, such as the amount of volatile components. The additive may be added directly or as a solution diluted with an appropriate solvent.

  When the material composition containing silica particles contains a solvent, examples of the solvent include one or more solvents selected from alcohols, ketones, esters, ethers, and hydrocarbon solvents. The boiling point of these solvents is preferably 100 ° C. or higher and 200 ° C. or lower.

  Next, the present embodiment will be described in more detail with reference to examples and comparative examples. The present embodiment is not limited to these.

<Evaluation method>
[Measurement of weight average molecular weight (Mw) of condensation reaction product]
A material composition which was a propylene glycol monomethyl ethyl acetate (PGMEA) solution was diluted with tetrahydrofuran (THF) so that the concentration of the condensation reaction product was 1% by mass, and measured by gel permeation chromatography (GPC). The weight average molecular weight (Mw) was determined as a value in terms of polyethylene glycol (PEG) as a standard substance.
(GPC measurement conditions)
・ GPC system: SCL-1APvp (manufactured by Shimadzu Corporation)
Column: Shodex KF-804L (Showa Denko Co., Ltd.) 2 in series Eluent: THF (flow rate: 1 mL / min)
Column operating temperature: 40 ° C

[Film evaluation items]
(1) X-ray photoelectron spectroscopy (XPS) measurement (measurement sample preparation)
The material composition was applied onto a Si substrate by spin coating to form a film, and then prebaked stepwise on a hot plate at 100 ° C. for 2 minutes and then at 140 ° C. for 5 minutes. Then, an insulating film having a thickness of about 100 nm was obtained by firing in an atmosphere at 600 ° C. and an oxygen concentration of 10 ppm or less.
(Spin coating conditions)
・ Spin coater: Mark-8
・ Main rotation speed: 1600rpm
(1000 rpm × 10 seconds + 1000 rpm × 30 seconds + 799 rpm × 10 seconds)
・ Main rotation time: 40 seconds (XPS measurement)
The measurement was carried out under the following conditions using a thermo-fischer ESCALAB250.
(Measurement condition)
Excitation source: mono. AlKα 15kVx10mA
・ Analysis size: about 1mm
・ Survey scan: 0-1100eV
・ Narrow scan: Si2p, C1s
・ Pass Energy
Survey scan: 100 eV; Narrow scan: 20 eV
The carbon / silicon composition ratio (C / Si) was calculated from the relative element concentration obtained from the narrow spectrum obtained by the measurement.

(2) Small angle incident X-ray small angle scattering (GI-SAXS) measurement (measurement sample preparation)
The material composition was applied onto a Si substrate by spin coating to form a film, and then prebaked stepwise on a hot plate at 100 ° C. for 2 minutes and then at 140 ° C. for 5 minutes. Thereafter, firing was performed in an atmosphere at 600 ° C. and an oxygen concentration of 10 ppm or less to obtain an insulating film having a thickness of about 400 nm. A sample cut into a 3 cm square was used as a measurement sample.
・ Spin coater: Mark-8
・ Main rotation speed: 1600rpm
(1600 rpm x 10 seconds + 1600 rpm x 30 seconds + 799 rpm x 10 seconds)
・ Main rotation time: 40 seconds (GI-SAXS measurement and evaluation)
GI-SAXS measurement was performed with BL03XU of SPring-8. Details of the experiment are described below.
An incident X-ray having an X-ray wavelength of 1 nm was used for GI-SAXS, and an imaging plate (R-AXIS IV manufactured by Rigaku) was used for the detector. The X-ray incidence to the sample was adjusted so that the angle formed by the incident X-ray and the sample surface was 0.14 °. During the measurement, the atmosphere was evacuated and the measurement temperature was room temperature. For the two-dimensional GI-SAXS pattern, only scattering within the sample surface was taken out and made one-dimensional. Of scattering intensity I ₁ at the time of the resulting scattering vector in measurement data (q) is 0.1 nm ^-1 (q), the ratio of scattering intensity I ₂ (q) when the said q is 0.2 nm ^-1 The case where (I ₁ (q) / I ₂ (q)) was 1.35 or less was marked as ◯, and the case where it was larger than 1.35 was marked as x.
The volume ratio of silica particles in the material was determined by the following method. Fitting the profile of the wide angle region where the scattering vector (q) of the obtained measurement data is 0.5 nm ^-1 or more with the profile of various silica particle volume ratios assuming that the silica particle is a hard sphere, the measured profile The volume ratio of the silica particles in the sample was the volume ratio of the silica particles in the model profile that coincided with.

(3) Electrical property evaluation (measurement sample preparation)
The material composition was applied onto a p-type low-resistance Si substrate by spin coating to form a film, and then pre-baked stepwise on a hot plate at 100 ° C. for 2 minutes and then at 140 ° C. for 5 minutes. Then, an insulating film having a thickness of about 100 nm was obtained by firing in an atmosphere at 600 ° C. and an oxygen concentration of 10 ppm or less.
(Spin coating conditions)
・ Spin coater: Mark-8
・ Main rotation speed: 1600rpm
(1000 rpm × 10 seconds + 1000 rpm × 30 seconds + 799 rpm × 10 seconds)
Main rotation time: 40 seconds Next, a capacitor was fabricated by vacuum-depositing aluminum having a thickness of about 250 nm on the surface of the insulating film and the back surface of the Si substrate. At this time, a circular upper electrode having a radius of 1 mm was formed on the surface of the insulating film through a mask.
(Electrical characteristics evaluation)
For the IV measurement, Agilent B1500A semiconductor device analyzer manufactured by Agilent, and a prober apparatus manufactured by Micromanipulator were used. The current density when the electric field strength is −3.5 MV / cm is defined as a leakage current value, and when the value is 1.0 × 10 ⁻⁶ A / cm ² or less, ○, larger than 1.0 × 10 ⁻⁶ A / cm ² The case was marked with x.

[Example 1]
To a 500 mL separable flask equipped with a reflux tube, a dropping funnel, and a stirrer, 22.2 g of methyltrimethoxysilane (MTMS), 8.9 g of tetraethoxysilane (TEOS), and 61.9 g of ethanol were added and stirred. The temperature was raised to 75 ° C. A mixture of 1.9 g of a 0.7% by mass nitric acid aqueous solution and 20.3 g of ion-exchanged water was added dropwise, followed by stirring at 75 ° C. for 2 hours. Thereafter, 103.1 g of ethanol was added, and 55.5 g of water-dispersed silica particles (PL-06, manufactured by Fuso Chemical Industry Co., Ltd., average primary particle size 6 nm, 6.0 mass% concentration) were added dropwise. After dropping, the temperature was raised to an internal temperature of 80 ° C. After 4 hours, heating was stopped and the mixture was allowed to cool to room temperature to obtain a reaction mixture.

  The above reaction mixture was transferred to a 1 L flask, 300 g of propylene glycol methyl ethyl acetate (PGMEA) was added, ethanol and water were removed by an evaporator, and a material composition A-1 was obtained (PGMEA solution having a solid content concentration of 18% by mass) 20% by mass of silica particles in the solid content of the material composition). Mw of obtained material composition A-1 was 1805.

XPS measurement, GI-SAXS measurement, and electrical property evaluation were performed on the film obtained by baking and curing the obtained material composition A-1 as described above. The volume ratio of the silica particles in the film obtained from the GI-SAXS measurement was 13%. The carbon / silicon atom composition ratio (C / Si) obtained from the XPS measurement was 0.62. The scattering intensity ratio I ₁ (q) / I ₂ (q) obtained from the GI-SAXS measurement was 0.90. The leakage current when the electric field strength was −3.5 MV / cm was 8.2 × 10 ⁻⁷ A / cm ² .

[Example 2]
To a 500 mL separable flask equipped with a reflux tube, a dropping funnel and a stirrer, 22.2 g of methyltrimethoxysilane (MTMS), 8.9 g of tetraethoxysilane (TEOS), and 82.5 g of ethanol were added, and the mixture was stirred. The temperature was raised to 75 ° C. A mixture of 3.86 g of a 0.7% by mass nitric acid aqueous solution and 18.4 g of ion-exchanged water was added dropwise, followed by stirring at 75 ° C. for 2 hours. Thereafter, 77.5 g of ethanol was added, and 95.4 g of water-dispersed silica particles (BS-01, manufactured by Fuso Chemical Industry Co., Ltd., average primary particle size 10 nm, 6.0 mass% concentration) was added dropwise. After dropping, the temperature was raised to an internal temperature of 80 ° C. After 4 hours, heating was stopped and the mixture was allowed to cool to room temperature to obtain a reaction mixture.

  The above reaction mixture was transferred to a 1 L flask, 300 g of propylene glycol methyl ethyl acetate (PGMEA) was added, ethanol and water were removed by an evaporator, and a material composition A-2 was obtained (PGMEA solution having a solid content concentration of 18% by mass) (The silica particles in the solid content of the material composition is 30% by mass). Mw of obtained material composition A-2 was 2983.

XPS measurement, GI-SAXS measurement, and electrical property evaluation were performed on the film obtained by baking and curing the obtained material composition A-2 as described above. The volume ratio of the silica particles in the film obtained from the GI-SAXS measurement was 20%. The carbon / silicon atom composition ratio (C / Si) obtained from the XPS measurement was 0.54. The scattering intensity ratio I ₁ (q) / I ₂ (q) obtained from the GI-SAXS measurement was 0.77. The leakage current when the electric field strength was −3.5 MV / cm was 2.9 × 10 ⁻⁷ A / cm ² .

[Comparative Example 1]
A material composition B-1 was prepared in the same manner as in Example 1 except that 95.2 g of water-dispersed silica particles (PL-06, manufactured by Fuso Chemical Industries, Ltd., average primary particle size 6 nm, 6.0 mass% concentration) were used. Obtained (a PGMEA solution having a solid content concentration of 18% by mass. Silica particles in the solid content of the material composition were 30% by mass). Mw of obtained material composition B-1 was 3407.

XPS measurement, GI-SAXS measurement, and electrical property evaluation were performed on the film obtained by baking and curing the obtained material composition B-1 as described above. The volume fraction of silica particles in the film obtained from the GI-SAXS measurement was 30%. The carbon / silicon atom composition ratio (C / Si) obtained from the XPS measurement was 0.54. The scattering intensity ratio I ₁ (q) / I ₂ (q) obtained from the GI-SAXS measurement was 1.39. The leakage current when the electric field strength was −3.5 MV / cm was 3.8 × 10 ⁻⁵ A / cm ² .

[Comparative Example 2]
A material composition B-2 was obtained in the same manner as in Example 1 except that 41.6 g of water-dispersed silica particles (PL-06, manufactured by Fuso Chemical Industries, Ltd., average primary particle size 6 nm) were used (solid content concentration 18). A mass% PGMEA solution (15 mass% silica particles in the solid content of the material composition). Mw of obtained material composition B-2 was 3200.

XPS measurement, GI-SAXS measurement, and electrical property evaluation were performed on the film obtained by baking and curing the obtained material composition B-2 as described above. The volume ratio of the silica particles in the film obtained from the GI-SAXS measurement was 9.4%. The carbon / silicon atom composition ratio (C / Si) obtained from the XPS measurement was 0.66. The scattering intensity ratio I ₁ (q) / I ₂ (q) obtained from the GI-SAXS measurement was 1.14. When the electric field strength was −3.5 MV / cm, the leakage current was 2.0 × 10 ⁻⁶ A / cm ² .

The results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1.

FIG. 1 shows the GI-SAX measurement results of Example 1 and Comparative Example 1, and FIG. 2 shows an enlargement of the scattering vector (q) in the GI-SAXS measurement result in the range of 0.05 nm ⁻¹ to 0.25 nm ^−1. The figure is shown. FIG. 3 shows the GI-SAXS measurement results of Example 1 and the fitting results when the particle volume ratio is 13% in the hard sphere model. FIG. 4 shows the measurement results of the IV characteristics of Example 1 and Comparative Example 1.

  The insulating material of the present invention includes an interlayer insulating film, an element isolation film, an STI insulating film, and a PMD (Pre Metal Dielectric) film for semiconductor devices such as liquid crystal display elements, integrated circuit elements, semiconductor memory elements, and solid-state imaging elements. , And can be suitably used as a planarizing film, a surface protective film, a sealing film, and the like.

Claims (4)

A semiconductor insulating material containing silicon atoms, carbon atoms, and oxygen atoms,
Including silica particles in a volume ratio of 13 % or more and 20 % or less,
The composition ratio (C / Si) of carbon atoms to silicon atoms is 0.54 or more and 0.62 or less, and the scattering vector q is 0.1 nm ^{−1 in} small angle incident X-ray small angle scattering (GI-SAXS) measurement. The ratio (I ₁ (q) / I ₂ (q)) of the scattering intensity I ₁ (q) at the time to the scattering intensity I ₂ (q) when the scattering vector q is 0.2 nm ⁻¹ is 0 An insulating material for a semiconductor, which is 90 or less. The insulating material for semiconductor according to claim 1, wherein an average primary particle diameter of the silica particles is 1 nm or more and 15 nm or less. A method for producing a semiconductor insulating material according to claim 1 or 2 ,
Applying a material composition containing a polysiloxane compound and silica particles to a substrate, and baking and curing the material composition;
The polysiloxane compound has the following general formula (1):
R ¹ Si (OR ² ) ₃ (1)
(Wherein R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, and R ² is each independently a hydrocarbon group having 1 to 6 carbon atoms.)
One or more silane monomers represented by the following general formula (2):
Si (OR ³ ) ₄ (2)
(In the formula, each R ³ is independently a hydrocarbon group having 1 to 6 carbon atoms.)
The manufacturing method of the insulating material for semiconductors obtained by carrying out hydrolysis polycondensation of the silane component which contains the 1 or more types of silane monomer represented by these in the quantity of 50 mass% or more in total. The manufacturing method of the insulating material for semiconductors of Claim 3 with which the said material composition contains 20 mass parts or more and 30 mass parts or less of the said silica particle with respect to a total of 100 mass parts of the said polysiloxane compound and the said silica particle.

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