JP2003059920A - Applied liquid for insulating film formation and forming method for insulating film for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an applied liquid for insulating film formation and a forming method for insulating film for semiconductor device wherein fine grooves are completely buried; application thick enough to flatten steps in a base can be implemented; uniform flatness is obtained throughout a base pattern; an insulating film containing no water, low in permittivity, and excellent in film characteristics is formed; and siloxanes are used. SOLUTION: The applied liquid is an applied liquid for insulating film formation for use in the manufacture of semiconductor devices, contains siloxanes containing Si atoms bonded with at least one kind of organic substituent, the content X of the siloxanes expressed by a prescribed equation determined from an integral value of the signal of<29> Si-NMR spectrum satisfying a prescribed equation, and has a self-fluidization temperature not less than 150 deg.C and not more than 300 deg.C. The forming method for insulating film for semiconductor device uses this applied liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention planarizes an insulating film for flattening and electrically insulating a substrate surface on which unevenness is formed on an underlayer, and in particular, a wiring structure of an electronic device, for example, an LSI multilayer wiring structure. In a solution containing siloxanes used as a precursor of an interlayer insulating film for forming an insulating layer, that is, in a coating liquid for forming an insulating film, a siloxane containing siloxanes having an organic substituent directly bonded to a Si atom as part of its structure is used. A method of evaluating the abundance ratio of the unit structure and using this value to evaluate the siloxanes for forming an insulating film, a coating liquid for forming an insulating film using siloxanes used for manufacturing a semiconductor device, a method for producing the same, and a semiconductor The present invention relates to a method of forming an insulating film for a device and a method of manufacturing a semiconductor device to which the insulating film is applied.

[0002]

2. Description of the Related Art Conventionally, as semiconductor devices have been highly integrated and the wiring of elements has become finer and multilayered,
The steps formed between the wirings are becoming larger and larger. Therefore, the embedding property of the insulating material formed between the wiring,
The flatness of the surface after forming the film is a serious problem. The tolerance of flatness is such that the depth of focus of the resist is reduced in order to follow the resolution in the photo process.
For example, there is also a report that it is necessary to suppress surface irregularities to 200 nm or less in a 0.7 μm line-and-space pattern. Since the suppression of the unevenness is required over the entire area of the chip or the wafer, it is necessary to completely flatten the wide area literally.

With respect to these problems, for example, Japanese Laid-Open Patent Publication No.
Chemical vapor deposition (O ₃ -TEO) using ozone and tetraethoxysilane as raw materials as shown in No. 1-77695.
A method is known in which an insulating film is formed by SAP-CVD) to fill and mitigate the steps of the base. However, although O ₃ -TEOS APCVD has a feature that good step coverage and excellent burying property are obtained, since film formation conformally occurs in wiring, planarization over a wide range on the substrate is not possible. It is impossible. O ₃ -TEOS APCVD also has a drawback that the deposition rate on a wide flat portion and a wiring pattern densely packed at a narrow interval is different, and thus flattening on a pattern in which the wiring density differs depending on the location is also difficult. is there.

Also, for example, LBVines and SKGupta, 198
6 IEEE VLSI Multilevel Interconnect Conference, p.5
06, Santa Clara, CA (1986) or R. Chebi and S. Mit
tal, 1991 IEEE VLSI Multilevel Interconnect Confere
nce, p.61, Santa, Clara, CA (1991) or BMSomero,
RPChebi, EUTravis, HBHaver, andW.K.Morrow, 1992
IEEE VLSI Multilevel Interconnection Conf., P.72,
There is also known a method of polishing an insulating film thickly deposited by chemical mechanical polishing (CMP) from the surface to flatten the surface, as shown in Santa Clara, CA (1992). CMP
According to the authors, even if the conditions are set appropriately, it is possible to obtain a flat shape in a wide area that is almost ideal.

However, prior to performing CMP,
The groove between the wires must be filled separately. That is, it is necessary to combine other methods such as CVD for filling the groove. CMP itself has a number of major problems, such as reduction in throughput, generation of particles, metal / alkali contamination, instability of detection of polishing end point, and increase in equipment cost, and it is still widely used. Has not reached the end.

If attention is paid only to a technique for filling a groove between wirings, a high-density plasma CVD method (biased HDP CVD) in which a bias is applied to a substrate has been paid attention in recent years.
S.Matsuo and M.Kiuchi, Jpn.J.Appl.Phys., 22, L210 (198
3), or K. Machida and H. Oikawa, J. Vac. Sci. Tech.
nol., B4,818 (1986) This is different from the usual CVD method.
This is a method of depositing an oxide film while anisotropically sputter etching the substrate surface with argon ions. At this time, ECR or ICP having a high plasma ion density is used as a plasma source. Although the formation of the interlayer insulating film by HDP is almost satisfactory as the trench filling technique,
Since projections due to sputter etching residue are generated on the entire surface of the pattern, flattening must be performed by another method such as CMP. Further, since the generation of particles and the low deposition rate, problems such as a decrease in throughput have not been solved yet.

On the other hand, Applied Physics Vol. 57, No. 12 (198
8) etc. introduced spin-on-glass method (SP
IN ON GLASS: SOG method) is a method of forming an insulating film by coating to reduce the unevenness of the underlying layer, which is widely used in the manufacture of semiconductor devices. For example, a hardened film of SiO ₂ by the SOG method is generally used as an interlayer insulating film for LSI multilayer wiring.
SOG is a technique of applying a solution containing oligosilanol or oligosilicates on a substrate with a spin coater and forming a cured film of SiO ₂ by heat curing, or an insulating film formed by the method, or for forming an insulating film Refers to the coating liquid. Since the SOG coating liquid has a property of flowing into the groove between the narrow wirings, the formed film is well filled in the groove between the wirings, and at the same time flows into the wide flat concave portion, so that the width is relatively wide. It also has the feature that it can flatten high steps. Since the SOG process is performed at a low temperature of about 400 ° C., it is favored as an interlayer insulating film after Al wiring which is easily damaged by heat.

Conventionally, the material of SOG has the general formula Si (OR) _n containing no organic substituent bonded to Si.
Oligosilicates called inorganic SOG represented by (OH) _4-n have been used. Since the volumetric shrinkage of about 20% occurs when the inorganic SOG is heat-cured, it has poor crack resistance and can be applied to only about 200 to 300 nm in one application. In order to alleviate the step due to the wiring having the wiring cross-sectional aspect ratio of about 1 or more, it is necessary to apply SOG at a thickness of at least about the wiring height, but since inorganic SOG is cracked, such thick coating cannot be performed. That is, inorganic SOG could not be used for flattening a step pattern having a large cross-sectional aspect ratio.

In order to solve the above-mentioned drawbacks of the inorganic SOG and to improve the shrinkability, flatness, etching rate, adhesion and crack resistance of the film, it has an organic substituent directly bonded to Si, that is, a chemical structure. An oligosiloxane called organic SOG represented by the general formula R _m Si (OR) _n (OH) _4-nm , which contains organic Si therein, has been studied,
Being developed. As the organic substituent, a methyl group is mainly used because of its thermal stability, degassing property, plasma resistance, film yield value and film flexibility, but other types of substituents such as phenyl group. Is sometimes used. Organic SOG
Compared with inorganic SOG, has a feature that the shrinkage rate of the film at the time of heat curing is small, and therefore the crack resistance is high. Further, since the etching rate for the etching gas containing CHF ₃ is as low as that of the CVD film, the organic SOG is applied thickly on the CVD oxide film on the pattern and cured, and then the CV is removed by the etching gas containing CHF _3.
Another feature is that the planarization process by etching simultaneously with the D film (constant-rate full-surface etchback method) can be easily configured.

However, even in the conventional organic SOG, the curing by heating starts at about 100 ° C. and the volume contraction occurs with it, so that even the surface once flattened by application shows irregularities following the underlying shape. Therefore, there is a problem that the flatness is not so good. Further, it is said that the area range on the substrate where the flattening effect due to the flow of the coating solution is exerted is at most a local area of the order of 10 μm, and the recesses between the wirings as wide as 10 μm or more and the projections on the wide wiring are as large as possible. The film thickness on the top becomes almost the same. That is, when seen from the visual field of the order of 10 μm or more, the step difference between the concave portion and the convex portion is not relaxed at all. In this way, the film thickness formed is
The organic SOG is ineffective for planarizing a wide area at the chip / wafer level because it depends on the density of the wiring pattern.

In addition, organic SOG also has a volume shrinkage of at least about 7% when it is heat-cured, and cracks due to shrinkage stress may be generated by coating and forming with a thickness of 500 nm or more, like inorganic SOG. Organic SOG is
Since the film quality is poor and water is easily contained or absorbed, troubles due to degassing from SOG are likely to occur in the subsequent process. Further, water causes an increase in the apparent permittivity, and therefore the delay due to the line capacitance increases, which is disadvantageous as an insulating film for high-speed wiring.

Several types of SOG have been reported which have dealt with the above-mentioned drawbacks of organic SOG. One is a ladder siloxane oligomer. This is expressed by the structural formula,

[Chemical 3] Thus, one methyl group (or phenyl group) is bonded to each Si, and a ladder-like ordered structure is formed. Ladder siloxane has a characteristic that it melts and flows like a crystal when heated due to its high regularity of structure, but it has a large shrinkage ratio and has very poor crack resistance, so thick coating is not possible. It has a fatal defect that it is poor in the upper active hydroxyl group (Si-OH), its adhesion to the base is poor, and peeling easily occurs.

As another measure, an inorganic SOG using a hydrogen siloxane oligomer or a perhydrosilazane oligomer as a raw material is also known. These new SOGs are characterized in that they do not have an organic group that directly bonds to Si in their structure, but instead have hydrogen that directly bonds to Si. In both cases, since oxygen contained in the atmosphere in the furnace is absorbed during heating and curing after coating and drying to cause volume expansion, the apparent shrinkage rate is small and thick coating is advantageous. However, the flatness in a wide area is not desirable because it has the same defect that the uneven shape of the base is traced due to the contraction from the application to the drying.
Furthermore, since free hydroxyl groups remain in the film even after heat curing, it is a cause of degassing and high dielectric constant.

To the problems listed above, no solution has been established so far in terms of materials. On the other hand, in order to improve the film characteristics of the insulating film of the semiconductor device, particularly the interlayer insulating film for LSI multilayer wiring, it is necessary to analyze siloxanes forming the insulating film. Generally, for the analysis of siloxanes contained in various materials, the sample itself or the siloxanes are extracted in an appropriate organic solvent, and the infrared spectrophotometric method, nuclear magnetic resonance (NMR) method, plasma inductively coupled emission method is used. A method of analyzing by a spectroscopic analysis method (see Japanese Patent Laid-Open No. 40403/1992) is known. Further, a method of detecting and quantifying a decomposition product generated by chemically decomposing siloxanes (Japanese Patent Publication No.
No. 2-8146) is also known. However, all of these methods are intended to measure the total amount of Si in the material.

By the way, although some methods for analyzing siloxanes are known as described above, an industrially useful method for analyzing the content ratio of the organic substituent in the organic SOG has not yet been established. In particular, organic SOG, that is, siloxanes for forming an insulating film, is used as an insulating film of a semiconductor device, especially LS
I There has been a problem that an industrially useful method for accurately and simply analyzing and evaluating it in association with the film characteristics of the I interlayer insulating film has not been established yet. Further, a coating liquid for forming an insulating film, a method for producing the same, and a method for forming an insulating film for a semiconductor device, which can sufficiently improve the film characteristics of an insulating film for a semiconductor device, particularly an interlayer insulating film for LSI multilayer wiring, have been earnestly desired. It was

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. It is possible to completely fill even fine grooves and to flatten the underlying step. An insulating film that can be applied with a sufficient thickness, can achieve uniform (global) flatness of the entire underlying pattern, and has a low dielectric constant that does not contain water and that is advantageous for high-speed wiring, that is, an insulating film with excellent film characteristics, In particular, it is an object of the present invention to provide a coating liquid for forming an insulating film and a method for forming an insulating film for a semiconductor device, which can form an interlayer insulating film for a semiconductor device, using siloxanes.

[0017]

Means for Solving the Problems The inventors of the present invention have conducted earnest researches on the characteristics of siloxanes and an interlayer insulating film for LSI multilayer wiring using the siloxanes. As a result, the content ratio of organic substituents in siloxanes, or existence ratio of the number of different Si atoms bonded organic substituents, that is to finding that the presence ratio of the unit structure of siloxanes greatly influences the properties of the film, furthermore, a result of intensive studies, ²⁹ Si-NMR
The organicity of SOG can be evaluated from the signal integration value of the spectrum, and the obtained organic SO
The inventors of the present invention have found that an insulating film having excellent film characteristics can be formed by using the G coating liquid, and have arrived at the present invention.

That is, a first aspect of the present invention is a coating liquid for forming an insulating film, which is used for manufacturing a semiconductor device,
A siloxane represented by the following formula [1] containing a Si atom bonded to at least one kind of organic substituent, and
The content ratio X represented by the following formula [2] obtained from the integrated value of the signal of the ²⁹ Si-NMR spectrum of the siloxane satisfies the following formula [2], and is 150 ° C. or higher 30
The present invention provides a coating liquid for forming an insulating film, which has a self-fluidizing temperature of 0 ° C or lower.

[Chemical 4] In the above formula [1], k, l, m, and n are integers of 0 to 1000. R: at least one organic substituent selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, which may be the same or different, and the phenyl group is a phenyl group having a substituent. But it's okay. The oxygen atom is bonded to any of Si, R, and H.

[Equation 3] In the above formula [2], Si obtained from A ₀ : ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having no —C bond, A ₁ : ²⁹ Si—Si determined from Si-NMR spectrum
Area of Si signal attributed to Si having one —C bond, A ₂ : Si obtained from ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having two —C bonds, A ₃ : Si obtained from ²⁹ Si-NMR spectrum
The area of the Si signal attributed to Si having three —C bonds is shown.

In the above formula [1], it is preferable that k = 0. Furthermore, in the above formula [1], k
It is preferable that = 1 = 0. Further, it is preferable that the self-fluidization occurs at a lower temperature than the condensation curing.

A second aspect of the present invention is to provide a method for forming an insulating film for a semiconductor device, characterized by using the above-mentioned coating liquid for forming an insulating film.

Here, a step of drying the coating solution for forming an insulating film after coating, fluidizing by holding at a temperature of 150 ° C. to 300 ° C. and further curing at a temperature of 350 ° C. to 450 ° C. It is preferable to include.

Further, a third aspect of the present invention is a coating solution for forming an insulating film used in the manufacture of a semiconductor device, which comprises the following formula [1] containing a Si atom bonded to at least one kind of organic substituent. Siloxane containing the siloxane represented by the following formula, and the content ratio X represented by the following formula [2] obtained from the integrated value of the signal of the ²⁹ Si-NMR spectrum of the siloxane satisfies the following formula [2]. A coating solution for forming an insulating film containing a compound is applied, dried after coating the coating solution for forming an insulating film, fluidized by being kept at a temperature of 150 ° C. or higher and 300 ° C. or lower, Provided is a method for forming an insulating film for a semiconductor device, which includes a step of curing at a temperature.

[Chemical 5] In the above formula [1], k, l, m, and n: integers from 0 to 1000 are shown. R: at least one organic substituent selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, which may be the same or different, and the phenyl group is a phenyl group having a substituent. But it's okay. The oxygen atom is bonded to any of Si, R, and H.

[Equation 4] In the above formula [2], Si obtained from A ₀ : ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having no —C bond, A ₁ : ²⁹ Si—Si determined from Si-NMR spectrum
Area of Si signal attributed to Si having one —C bond, A ₂ : Si obtained from ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having two —C bonds, A ₃ : Si obtained from ²⁹ Si-NMR spectrum
The area of the Si signal attributed to Si having three —C bonds is shown. Here, it is preferable to maintain the temperature at 150 ° C. or higher and 300 ° C. or lower for 30 seconds or longer. Further, it is preferable to perform the curing in nitrogen.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The method for evaluating siloxanes for forming an insulating film used in the present invention is to evaluate at least one organic compound contained in a coating liquid for forming an insulating film for a semiconductor device, for example, an insulating film for an LSI multilayer wiring. The siloxanes containing Si atoms bound to the substituents are analyzed for the abundance ratio of at least one Si atom with a different number of bound organic substituents, by or on this basis, for example in siloxanes. This is a method of determining the content ratio of organic substituents and evaluating the organicity of siloxanes, for example, by using the ratio. In particular, it is a method of evaluating the organicity by determining the existence ratio and the content ratio from the area of the signal due to organic silicon in ²⁹ Si-NMR.

A solution containing siloxanes used in the present invention, that is, a coating liquid for forming an insulating film (hereinafter, simply referred to as a coating liquid) is an insulating film for a semiconductor device (hereinafter, referred to as a coating liquid).
It is used as a precursor for forming an insulating film) and is a solution of siloxanes containing Si atoms bonded to at least one kind of organic substituent or a solution of such siloxanes dissolved in an organic solvent. However, any SOG solution for forming an SOG film, an organic SOG solution, or the like can be used. Here, the organic substituent may be any of a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, or may contain two or more kinds. Further, the number of organic substituents bonded to one Si atom may be 1 to 3.

Here, the siloxanes used in the present invention can be represented by the following formula [1], but the way in which these unit structures are bonded is not particularly limited, and they may be linear or branched. Either is fine. Further, these may be mixed and used.

[0026]

[Chemical 6] In the above formula [1], k, l, m, and n: integers from 0 to 1000 are shown. R: at least one organic substituent selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, which may be the same or different, and the phenyl group is a phenyl group having a substituent. But it's okay. The oxygen atom is bonded to any of Si, R, and H.

Such siloxanes are preferably siloxane oligomers used for the purpose of forming an insulating film, and more preferably have a degree of polymerization of 2 to 50.
0 siloxane oligomer is preferred. That is,
Number of repeating unit structures (a) to (d) of the siloxane oligomer represented by the above formula [1] [k + l + m + n]
Is more preferably within the range of 2 to 500. Here, if the degree of polymerization (repetition number) exceeds 500, the viscosity of the coating solution (SOG solution) composed of siloxane and a solvent becomes too high, and if it is less than 2, siloxane easily evaporates in the insulating film forming step, In either case, it becomes difficult to form the insulating film.

[0028]

[Chemical 7] In the unit structures (a) to (d), R represents at least one organic substituent selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, and may be the same or different. The phenyl group may be a phenyl group having a substituent.

In the present invention, when evaluating the siloxanes for forming an insulating film, the content ratio of the organic substituents of the siloxanes is analyzed, or Si atoms (Si—C bond having different numbers of bonded organic substituents) are analyzed. Si atoms whose number is 0 to 4), that is, at least one of the unit structures (a) to (d) is analyzed, and the abundance ratio thereof is measured. The method of analyzing the content ratio of the organic substituents of the siloxanes used in the present invention or the method of measuring the existence ratio of the unit structures (a) to (d) is not limited, but a nuclear magnetic resonance (NMR) method is used. Is preferred. More preferably, such abundance ratio is preferably obtained from the integrated value of the signal of the ²⁹ Si-NMR spectrum.

In carrying out the nuclear magnetic resonance (NMR) method, first, a sample siloxane, for example, an SOG solution is dissolved in a deuterium solvent. The deuterium solvent used here is not particularly limited as long as the components in the SOG solution are not separated from the solution by adding the deuterium solvent, and for example, deuterated chloroform, deuterated acetone, deuterated methanol and the like can be used. . If the concentration of the sample is too low, sufficient detection sensitivity cannot be obtained, and if it is too high, the ratio of the deuterium solvent decreases, and the frequency stability of the NMR apparatus becomes unsatisfactory, so 10-90% is preferable.

The sample tube used for ²⁹ Si-NMR measurement is preferably made of Teflon (registered trademark). This is usually a glass NMR sample tube due to silicate glass ²⁹ S
This is to prevent the i signal from appearing. In the ²⁹ Si-NMR measurement performed for the purpose of the present invention, it is desirable not to decouple hydrogen nuclei. this is,
^This is because the intensity of the ²⁹ Si-NMR signal may be attenuated depending on the sample because the sign of the nuclear Overhauser effect factor of ²⁹ Si-NMR is negative, and in order to ensure the quantification of the integrated intensity of the signal. Is. It is also preferable to add a relaxation reagent such as tris (acetylacetonato) chromium (III) or tris (acetylacetonato) iron (III) in order to shorten the measurement time.

The respective signals of the ²⁹ Si-NMR spectrum obtained by the measurement are assigned, and from the respective signal areas, the abundance ratios of the unit structures (a), (b), (c) and (d), or further organic The abundance ratio of Si atoms bonded to the substituent is calculated. The content ratio of the organic substituent can be defined in several different ways depending on the purpose, and it may be used properly according to the purpose or need. For example, Si-C
The area of the Si signal attributed to Si having no bond is A ₀ , and the Si attributed to Si having one Si—C bond
Si having a signal area of A ₁ and two Si—C bonds
The area of the Si signal attributed to A ₂ and Si-C
When the area of the Si signal attributed to Si having three bonds is represented by A ₃ , the organic scale (represented by X) can be defined by the following formula [3] or formula [4].

[0033]

[Equation 5] Formula [3] is a formula representing the ratio of the number of organic substituents to the number of Si atoms in siloxane, and formula [4] is a formula representing the ratio of the number of organic Si atoms to the number of Si atoms in siloxane. The form of the equation for evaluating the organicity can be defined according to the purpose of analysis without being limited to the above equations [3] and [4].

According to the evaluation method used in the present invention, in the analysis of the content ratio of the organic substituents of the organic siloxanes, the abundance ratio for each unit structure, which was impossible by the conventional method, can be obtained. The organic substituent content ratio in the siloxane can be easily determined. Therefore, this evaluation method can be used, for example, in the organic evaluation of siloxanes in a solution containing organic siloxanes used for forming an insulating film of a semiconductor device, particularly an interlayer insulating film for LSI multilayer wiring. Depending on the evaluation method used, the film properties such as chemical resistance and water resistance of this insulating film can be predicted in advance. Further, according to the present invention, there is also an effect that quality control at the time of manufacturing the SOG used for the insulating film is appropriately performed.

A third aspect of the present invention is a coating liquid for forming an insulating film for a semiconductor device using siloxanes, for example, an interlayer insulating film for LSI multilayer wiring (hereinafter simply referred to as an insulating film) based on the above evaluation method. Is a method of forming an insulating film.

The coating liquid for forming an insulating film used in the method for forming an insulating film according to the third aspect of the present invention will be described below. Here, the present inventors have found that there is a close relationship between the chemical structure of siloxanes and the characteristics of the SOG film. That is, a coating solution containing siloxanes, preferably siloxane oligomers, in which the following abundance ratio X obtained from the integrated value of the ²⁹ Si-NMR spectrum signal of the siloxanes represented by the above formula [1] satisfies the following formula [2]: It has been found that the characteristics of the insulating film formed are excellent when using.

[0037]

[Equation 6] In the above formula [2], Si obtained from A ₀ : ²⁹ Si-NMR spectrum
Area of Si signal attributed to Si having no —C bond A ₁ : ²⁹ Si—Si determined from Si-NMR spectrum
-C combine one with the area of the Si signal ascribed to Si A _2: ²⁹ Si-NMR determined from the spectrum, Si
-C combine two having the area of the Si signal ascribed to Si A _3: ²⁹ Si-NMR determined from the spectrum, Si
-Area of Si signal attributed to Si having three C bonds

Here, the reason why the characteristics of the insulating film are excellent when the coating liquid containing the siloxane whose content ratio X represented by the above formula [2] is 80% or more is used is (1)
Since the water absorption is reduced, the amount of degassing and the dielectric constant can be suppressed to a low level. (2) The crack resistance can be improved to enable thick coating, and (3) the dry etching rate can be reduced, so that etch back Wide margin,
And so on.

Next, the insulating film forming coating solution provided in the present invention will be described. It can be said that the coating liquid provided in the present invention evaluates the above-mentioned organic scale by the above formula [3]. In the present invention, a disordered structure having a weight average molecular weight of 1500 or more and 6000 or less represented by a composition formula (CH ₃ ) _y SiO _{2 -y / 2} (y in the formula is 0.8 or more and 1.3 or less) is used. Methyl siloxane oligomer with boiling point of 120 ℃ or more 20
The present invention provides a coating liquid, which is characterized by being dissolved in a solvent containing an organic compound at 0 ° C or lower as a main component. This coating solution is a conventional organic SOG (the range of y is 0.3 to 0.
Unlike 6), the value of y in the composition formula is 0.8 or more and 1.3.
It is characterized by the following, and is characterized by having an irregular structure with respect to the ladder siloxane having an ordered structure.

By limiting the value of y to 0.8 or more in the composition formula of the methylsiloxane oligomer, it is possible to almost eliminate the shrinkage of the methylsiloxane oligomer during heat-polymerization curing. Therefore, it can be applied thickly,
Works favorably for flatness. Further, due to this limitation, the water absorption rate of the methyl siloxane oligomer can be made almost 0, and the dielectric constant can be lowered to 3.5 or less. It is possible to impart a feature of forming an SOG film which is advantageous to the above. When y is less than 0.8, normal organic S
It has similar properties to OG, and has shrinkage, water absorption,
The flattening performance and the dielectric constant can be obtained only within the range of the prior art. Further, when y exceeds 1.3, heat polymerization becomes difficult, and a rubber-like material is formed without forming a film.
The upper limit of y was 1.3.

According to the conventional technique, the higher the value of y, the lower the adhesion to the base, and it was impossible to put it to practical use. Ladder methyl siloxane is also represented by the same composition formula as that of the present invention, and is within the range of y of the present invention (y = 1 is required for forming a ladder structure), but the adhesion is also the same. As described in the prior art, it is difficult to use due to the problems of poor heat resistance and large shrinkage.

In the present invention, the problem of adhesion reduction due to increase in y is solved by defining the siloxane skeleton as an irregular structure, defining the molecular weight, and defining the solvent. The introduction of the disordered structure introduces a large amount of Si-OH terminations that contribute to adhesion into the oligomer structure and makes the Si-O-Si network structure sparse, thus making the film soft and absorbing stress. It is considered that the increase of the adhesiveness contributes to the improvement of the adhesive strength. Although an appropriate parameter that defines the disordered structure has not been found yet, it is presumed that the conventional organic SOG is likely to have a disordered structure even if y is increased and has poor adhesion. If the molecular weight is also less than 1500, volume shrinkage during polymerization is significant, and internal stress is likely to occur, causing cracking and peeling. Further, as for the solvent, if a solvent having a boiling point of less than 120 ° C. is used, not only coating unevenness is likely to occur due to in-plane difference in drying rate, but also stress due to drying is significantly generated, which adversely affects adhesion.

The reason why the weight average molecular weight of the methyl siloxane oligomer is limited to 1500 to 6000 is as follows.
In addition to solving the above-mentioned problem of adhesion, if it is less than 1500, a continuous coating film is not formed, and if it exceeds 6000, the viscosity of the coating liquid becomes too high, so that radial coating unevenness called striation occurs. This is because. Most preferably, the weight average molecular weight is 1500 to 3500.

As a solvent for dissolving the methylsiloxane oligomer, a solvent containing an organic compound having a boiling point of 120 ° C. or more and 200 ° C. or less as a main component is used. If the boiling point is lower than 120 ° C., most of the solvent is volatilized by the rotation during coating, so that flattening cannot be achieved by sufficiently flowing the coating liquid. Further, as described above, the decrease in adhesion due to the stress generated by drying becomes a problem. On the other hand, the boiling point is 20
If the temperature exceeds 0 ° C., the drying will be significantly slowed down, the throughput will be reduced, defects will be generated during the transportation of the substrate, and foaming or carbon residue will be generated during the heating step, so that it cannot be used.
The more preferred solvent boiling point range is between 130 and 160 ° C.

The viscosity of the solvent has a great influence on the filling performance of fine grooves and the uniformity of the coating film. A solvent having a viscosity of 2.0 cP or less at 25 ° C. is preferably used. That is, when the viscosity of the solvent is larger than 2.0 cP, the groove of 0.2 μm or less is not completely filled, and a striation, which is called a striation, is formed from the center of the substrate to the periphery during coating. The frequency of occurrence of film thickness unevenness significantly increases.

Solvents satisfying the requirements of the present invention include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, di-n-butyl ether, diisobutyl ether, di-n. -Amyl ether, methyl n-amyl ketone, methyl isoamyl ketone, n-amyl acetate, isoamyl acetate,
N-hexyl acetate or the like can be used.

Although these solvents can be used alone, 2
You may use it in combination of 2 or more types. Further, other low boiling point solvents such as methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, water, and butyl acetate may be added to lower the viscosity and improve the coating performance. However,
The volume ratio of the solvent having a boiling point other than 120 ° C. to 200 ° C. is preferably not more than 50% of the whole solvent. In the coating liquid of the first aspect of the present invention described below and the coating liquid used in the second or third aspect of the present invention, the above-mentioned solvent may be used to dissolve the siloxanes. Needless to say.

When the coating solution satisfying the above requirements is used, the detailed reason is not clear, but the film once dried and solidified is softened upon heating and reflowed to further flatten. A characteristic phenomenon called self-fluidization occurs. Planarization by self-fluidization is performed at a temperature of 150 to 2 which is lower than that at which condensation curing of methylsiloxane oligomer occurs.
It occurs in the range of 00 ° C. Due to this phenomenon, conventional SOG
A far wider area can be flattened compared to.

For the above reasons, by using one or both of the coating solutions provided by the present invention, uniform flatness of the entire underlying pattern can be achieved and fine grooves can be completely formed. It is possible to form an insulating film that can be embedded in a substrate, can be applied with a sufficient thickness to flatten the underlying step, has a low dielectric constant without water, has excellent insulating properties, and is advantageous for high-speed wiring. it can.

The organic SOG coating liquid having such characteristics can be produced by the method for producing a coating liquid described later. That is, a compound such as alkoxysilane or alkylalkoxysilane, particularly one compound selected from the group consisting of tetraalkoxysilane, methyltrialkoxysilane and dimethyldialkoxysilane or 2
A mixture of two or more species is used as a raw material, and the mixture is mixed so that the molar concentration of Si—CH ₃ is 80% or more and 130% or less of the molar concentration of Si in the entire raw material.
To 4 times the molar amount of water, using an organic carboxylic acid as a catalyst, to a temperature of 40 ° C. or higher and 80 ° C. or lower for polymerization,
A solvent containing an organic compound having a boiling point of 120 ° C. or more and 200 ° C. or less as a main component is added to the polymerization product to dilute it, and the diluted solution is distilled under normal pressure or reduced pressure to distill water and alcohol by-products of the polymerization reaction. Distill off.

Examples of tetraalkoxysilanes include tetra
Methoxysilane (Si (OCH₃) _Four), Tetraetoki
Sisilane (Si (OC₂H_Five)_Four) Is commonly used
It In addition, as methyltrialkoxysilane,
Lutrimethoxysilane (CH ₃Si (OCH₃)₃)Ah
Ruiha methyltriethoxysilane (CH₃Si (OC ₂
H_Five)₃) Is commonly used. Also, dimethyldia
As lucoxysilane, dimethyldimethoxysilane
((CH₃)₂Si (OCH₃)₂), Dimethyl diet
Xysilane ((CH₃)₂Si (OC₂H_Five)₂) Is for
Can be These raw materials may be used alone or in a mixture to obtain S
i-CH₃Is 8 times the molar concentration of Si in the entire raw material.
Pre-blend to be 0% to 130%
deep. This value is in the coating liquid provided in the present invention.
And the compositional formula of the methylsiloxane oligomer is (C
H₃)_ySiO_{2-y / 2}Is equal to the value of y.
That is, y in the formula must be 0.8 or more and 1.3 or less
There is.

For example, when methyltrimethoxysilane is used alone as the raw material, Si--CH ₃ / total S is used.
Since i = 100% corresponds to y = 1, it can be used as it is. When tetramethoxysilane and methyltrimethoxysilane are mixed, the mixing ratio r is r = [Si
If (OCH ₃ ) ₄ ] / [CH ₃ Si (OCH ₃ ) ₃ ], then 0 ≦ r ≦ 0.25, and 0.8 ≦ y <1.0. When mixing tetramethoxysilane and dimethyldimethoxysilane, the mixing ratio r is r =
[Si (OCH ₃ ) ₄ ] / [(CH ₃ ) ₂ Si (OCH
₃ ) ₂ ], and if 7/13 ≦ r ≦ 1.5, then 0.
It can be set to 8 ≦ y ≦ 1.3. As described above, the raw materials can be used in combination of two kinds or three kinds.

Si-C compounded or contained in a single raw material
When the molar concentration of H ₃ is less than 80% of the molar concentration of Si in the whole raw material, _{y in the} composition formula: (CH ₃ ) _y SiO _{2 -y / 2} represented by y is 0. Since it is less than 8, the desired characteristics cannot be exhibited for the reasons described above. Further, when the molar concentration of Si—CH ₃ contained in the mixture or the single raw material exceeds 130%, y of the similarly produced methylsiloxane oligomer is 1.3.
Therefore, the cured film is not formed for the reason described above.

When water is added to this raw material in an amount of 2 to 4 times the molar concentration of Si of the entire raw material and an organic carboxylic acid such as formic acid, acetic acid or succinic acid is added, the condensation reaction starts immediately and the polymer The formation takes place. When the amount of water is less than twice the molar amount of the raw material, not only the reaction rate is remarkably lowered, but also the residual ratio of the alkoxyl group in the polymer is increased, so that carbon in the formed film is likely to remain. Further, when the amount of water exceeds four times the molar amount of the raw material, the production reaction takes place too rapidly, which makes control difficult and increases the proportion of free hydroxyl groups (Si-OH) in the methylsiloxane oligomer. Therefore, it lacks storage stability.

The concentration of the organic acid as a catalyst is not particularly limited because it does not affect the structure or state of the product so much, but if the concentration is too high, the solution becomes acidic and the stability of the coating solution is affected. The concentration is as low as possible, preferably about 1/1000 mol to 1/100 mol of the raw material.
Inorganic acids other than organic acids, such as hydrochloric acid and phosphoric acid, do not use because they affect the metals on the coated substrate.

After the addition of water, the mixed solution is generally incompatible, so that vigorous mixing must be continued using a stirrer or the like. Within a few minutes to a few hours, an alcohol, which is a double product of the hydrolysis reaction, is produced, and the hydrophilicity of the polymer is increased, so that they become compatible with each other. Prior to this polymerization reaction, a solvent such as alcohols may be added for pre-dilution. For example, the addition of 0.5 times the molar amount of methanol as the starting material can reduce the heat generation in the initial stage of the reaction, increase the compatibility, improve the stability of the reaction, and delay the polymerization reaction. As the solvent to be added for this purpose, methanol, ethanol, dioxane or the like, which is about 0.2 to 3 times the molar amount of the raw material, is used.

In order to polymerize the methylsiloxane oligomer to a weight average molecular weight of 1500 to 6000, the mixture is heated to a temperature of 30 ° C or higher and 80 ° C or lower. It is preferable to carry out the polymerization at a low temperature when the ratio y of the molar concentration of Si—CH ₃ contained in the compound or the single raw material to the molar concentration of Si of the entire raw material is relatively small, and at a high temperature when y is relatively large. . If the heating temperature is less than 30 ° C,
The polymerization rate is extremely reduced, and the desired molecular weight cannot be obtained. On the other hand, if the heating temperature exceeds 80 ° C, boiling of alcohol as a by-product or polymerization occurs extremely rapidly, which makes control difficult. Generally, it is preferable that the reaction is carried out at a temperature of about 50 ° C., which is tightly closed and stored in a thermostat. The time required for the reaction depends on the temperature, but is not particularly limited, and an appropriate time may be selected from about 4 to 120 hours while measuring the molecular weight.

The polymerization product thus obtained includes
In addition to water initially added as a raw material, alcohol as a by-product and, when a solvent is added for dilution, the solvent and the like coexist. It is necessary to remove this, but if it is distilled or dried as it is, the concentration of the methyl siloxane oligomer rises sharply, and the polymerization reaction rate accelerates, resulting in a gel with a molecular weight of several hundred thousand or more. When removing water, alcohol and solvent, it is necessary to devise a method that does not increase the concentration of the methylsiloxane oligomer. To do this, the main solvent used for dilution, ie boiling point 120 ° C
A solvent containing an organic compound as a main component at a temperature of 200 ° C. or higher,
It is necessary to add and dilute in advance, and then dilute the diluted solution as it is under normal pressure or reduced pressure. As distillation conditions, it is important to select a temperature and pressure at which water, alcohol, and solvent are distilled off, but the main solvent is not distilled.

Needless to say, the same main solvent as that used for the coating solution provided in the present invention can be used. Thus, the solution of the methylsiloxane oligomer from which water, alcohol and solvent have been removed can be used as it is, or after adding an appropriate solvent and optionally performing operations such as filtration and aging, a coating solution can be obtained.

The method for forming an insulating film for a semiconductor device according to the third aspect of the present invention uses the insulating film forming coating solution provided in the present invention, wherein the insulating film forming coating solution is applied and dried, It includes a step of fluidizing by holding at a temperature of 150 ° C. or more and 300 ° C. or less, preferably 30 seconds or more. After this fluidizing step, further 350 ° C
It is preferable to cure in nitrogen at a temperature of 450 ° C. or higher to form an insulating film. Thus, in the present invention, a semiconductor device having an insulating film having excellent film characteristics, particularly an interlayer insulating film, can be manufactured.

This is basically the same as the conventional organic SOG film coating and forming method, but the self-fluidizing temperature of the SOG of the present invention is 150 ° C. or higher and 300 ° C. or lower. The most distinctive feature is that the temperature is kept at a temperature of not lower than 300 ° C. and not higher than 300 ° C. for preferably 30 seconds or longer to complete the self-flow flattening. That is, the coated and dried film is fluidized again in this temperature range, and a high wide area flatness can be obtained. The subsequent process is nothing but the process called normal SOG curing.

From the above reason, the coating liquid for forming an insulating film according to the first aspect of the present invention is kept at a temperature of 150 ° C. or higher and 300 ° C. or lower to form a self-flowing flattening film. It is a coating liquid capable of That is, the insulating film forming coating solution according to the present embodiment is a solution of a methylsiloxane oligomer dissolved in a solvent containing an organic compound as a main component, and the molar concentration of Si—CH ₃ in the methylsiloxane oligomer is methylsiloxane. It is characterized in that it has a self-fluidizing temperature of not less than 80% and not more than 130% of the molar concentration of Si of the entire oligomer and not less than 150 ° C and not more than 300 ° C. In this embodiment, the solvent containing a methylsiloxane oligomer and an organic compound as a main component includes all of those described in the coating liquid for forming an insulating film provided in the present invention.

The method for forming an insulating film for a semiconductor device according to the second aspect of the present invention uses the coating liquid for forming an insulating film according to the first aspect of the present invention. In this embodiment, it is preferable to include a step of applying the insulating film-forming coating liquid according to the first embodiment of the present invention, drying it, and then maintaining the temperature at 150 ° C. or higher and 300 ° C. or lower for fluidization.
It is more preferable to maintain the temperature at not lower than 300 ° C. for not lower than 30 seconds. Further, after the fluidizing step, it is preferable to further cure in nitrogen at a temperature of 350 ° C. or higher and 450 ° C. or lower to form an insulating film.

[0064]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) The unit structures (a), (b), (c) in the siloxane oligomer contained in the commercially available organic SOG,
The abundance ratio of (d) and the content ratio of the organic substituent were analyzed. Here, two types of organic SOGs, sample A (SF1014 manufactured by Sumitomo Chemical Co., Ltd.) and sample B (Type 12000T manufactured by Tokyo Ohka), were analyzed. 1.5 ml of organic SOG (each of sample A and sample B) and about 40 mg of tris (acetylacetonato) chromium (III) were added to 1.5 ml of heavy acetone.
Was added and dissolved to form a uniform solution. This solution is 1
Place it in a 0 mm Teflon (registered trademark) NMR sample tube,
Fourier transform NMR spectrometer (GX270, manufactured by JEOL Ltd.)
²⁹ Si-NMR was measured. Observation center frequency 53.6
7MHz, observation frequency range 16kHz, data point 16k or 32k, number of integration 10000-4500
0, tetramethylsilane was used as an internal standard for chemical shift.

An example of the obtained ²⁹ Si-NMR spectrum is shown in FIG. The relative ratio of A ₀ , A ₁ , A ₂ and A ₃ was determined from the area of each signal shown in the figure. Note that FIG.
The peak area of is proportional to the number of Si atoms in the corresponding unit structure. Here, in the case of the unit structures (a) and (c), it is the total value of a plurality of peak areas shown in the figure. Table 1 shows the results of calculating the organic substituent content ratio defined by the above formula [3]. In this embodiment, R
Is a methyl group.

As described above, when the evaluation method used in the present invention is used, in the analysis of the content ratio of the organic substituents of the organic siloxanes, ²⁹ Si-NMR measurement is performed, which is impossible with the conventional method. The abundance ratio for each existing unit structure can be determined, and for example, the abundance ratio of the unit structures (a), (b), (c) and (d) and the organic substituent content ratio in the organic SOG can be easily determined. .

[0067]

[Table 1]

(Example 2) As raw materials, methyltrimethoxysilane and tetramethoxysilane were dissolved in methanol in the proportions shown in Table 2, water and 0.002 mol of formic acid in the proportions shown in Table 1 were added, and the mixture was stirred. And a polymerization reaction was performed at 30 to 60 ° C. for 24 hours. 650 ml of a 1: 1 mixture of benzene and ethylene glycol monoethyl ether was added to the product, and distilled under reduced pressure to remove excess methanol and water to prepare a coating solution having a solid content concentration of about 20% by weight. When the weight average molecular weight of the siloxane oligomer contained in this coating solution was measured by gel permeation chromatography, it was about 3,0.
00, which corresponds to a degree of polymerization of 40 to 50.

A 6-inch diameter silicon wafer was spin-coated with this coating solution at a rotation speed of 3,000 rpm,
Bake at 150 ℃, 200 ℃, 250 ℃ for 60 seconds each,
Then, it was heated in a nitrogen stream at 400 ° C. for 30 minutes to form an insulating film. The results of measuring shrinkage, dielectric constant and water absorption of this film are shown in Table 2 and FIG. 2 together with the value of X in the formula [2].

Here, the shrinkage rate was evaluated by forming coating films of different thicknesses on the semiconductor substrate after cleaning by controlling the number of rotations, and calculating the shrinkage rate from the following formula [5]. Shrinkage _{(%) = {(t b} -t a) / t b} × 100 [5] However, t _a is the thickness after curing, t _b is the thickness after pre-baking.

The dielectric constant is A on the entire surface of the semiconductor substrate after cleaning.
a film having a thickness of about 300 n by controlling the rotation speed by the method described above.
After forming a coating film of m, pre-baking and curing treatment, an Al electrode of about 3 mm square is vapor-deposited using a metal mask, and the end portion of the film is etched with diluted hydrofluoric acid to vapor-deposit Al on the entire lower surface. The electrostatic capacitance between the Al films was measured and determined from the electrode area and the film thickness.

Regarding the water absorption, the cured film was left in a clean room for 24 hours, and the water contained in the film was measured by an electrolytic cell moisture meter (MEA (Moisture Evaluation Ana
It was measured by measuring the amount of water generated up to 400 ° C. with a lyzer (made by DuPont). As is clear from Table 2 and FIG. 2, there is a clear correlation between X and the film properties, and X ≧
It was found that at 80%, the shrinkage rate, dielectric constant and water absorption were all small, and excellent film characteristics were obtained.

[0073]

[Table 2]

Example 3 First, based on the method for producing a coating solution provided by the present invention, the coating solution for SOG formation provided by the present invention was produced by the following procedure. The raw material compounding ratios, synthesis conditions, and typical film properties are all listed in Tables 3 and 4. Table 3 shows various combinations of raw materials, and Table 4 shows data obtained when various synthesis conditions are changed. Tables 3 and 4
The measured data are also described in. A detailed description of the measuring method is given below. Table 3 shows the measured film properties.
4 is the same. In addition, those other than the scope of the present invention were marked with an asterisk (*) in front of the numbers to make a comparative example for control.

(Synthesis of coating liquid) As a raw material, tetramethoxysilane, methyltrimethoxysilane and dimethyldimethoxysilane each having a purity of 99% or more were used.
The mixture was mixed in the proportions shown in Table 1, water in the proportions shown in Tables 3 and 4 was added, and a 1N formic acid aqueous solution was added as formic acid to 0.0
After adding 02 mol and stirring to form a uniform solution, the solution was sealed and immersed in a constant temperature water bath at the temperatures shown in Tables 3 and 4,
Polymerization reaction was carried out by holding for the times shown in 4 and 4. Methyl n-amyl ketone (2-
Heptanone, boiling point 151 ° C), and 50 To at 50 ° C
Distillation was carried out using a rotary evaporator under reduced pressure of rr to remove excess methanol and water. Then, it was further diluted with methyl n-amyl ketone (2-heptanone) to prepare a coating liquid having a solid content concentration of 20% by weight. Table 4 shows the results of measuring the weight average molecular weight of the siloxane oligomer contained in this coating solution by gel permeation chromatography. It can be seen that the coating solutions synthesized in the examples of Table 4 all satisfy the conditions of the coating solution provided by the present invention. However, it is excluded because there is no measurable method for the irregularity of the Si-O-Si network, but it is predicted that the shrinkage rate described below is very small and that it does not have a regular structure such as a ladder structure. Is known by itself.

This coating solution was spin-coated on a silicon wafer having a diameter of 6 inches at a rotation speed of 3000 rpm, and
The coating film was prepared by baking at 0 ° C., 200 ° C. and 250 ° C. for 60 seconds each, and then heating in a nitrogen stream at 400 ° C. for 30 minutes. The results of measurement of shrinkage, dielectric constant and water absorption of this film are shown in Table 3 together with the value of y in the following composition formula 1.
Are also shown. (CH ₃ ) _y SiO _{2 -y / 2} (Compositional Formula 1) Here, the shrinkage rate, dielectric constant and water absorption rate were measured and evaluated in the same manner as in Example 2.

As is clear from Tables 3 and 4, there is a clear correlation between y and the film characteristics, and 0.8 ≦ y ≦
It was found that when the ratio was 1.3, excellent film characteristics such as a low shrinkage ratio, a low dielectric constant, and a low water content were obtained.

Next, a method of forming an insulating film according to the present invention will be described with reference to the drawings. FIG. 3 is a partial cross-sectional view showing the manufacturing process of the insulating film according to the present invention. Figure 3
In the step shown in (1), after a wiring layer having a thickness of 1.2 μm is formed on the semiconductor substrate 1 which has been subjected to a desired process, the wiring layer is patterned to form wirings 2a, 2b and 2c (wiring width = 1 μm). Line-and-space wiring pattern 2 consisting of the distance between the wirings 2a and 2b = the distance between the wirings 2b and 2c = 1 μm, and the wirings 3a and 3b having the wiring width = 0.5 μm
And 3c (space between wirings 3a and 3b = wiring 3b and wiring 3)
The line-and-space wiring pattern 3 having a distance from c = 0.5 μm) was formed. The distance between the wiring pattern 2 and the wiring pattern 3 was 3 μm. By this step, a step was generated between the semiconductor substrate 1 and the wiring patterns 2 and 3.

Next, in the step shown in FIG.
Tetraethoxysilane (TEO) is formed on the entire surface of the semiconductor substrate 1 and the wiring patterns 2 and 3 obtained in the step (1).
S) -based plasma CVD method for SiO ₂
Layer 4 was formed with a thickness of 300 nm. The CVD oxide film 4 has good step coverage, but it is impossible to fill the groove between the wirings because the film is formed along the shape (step) of the base.

Next, in the step shown in FIG. 3C, various coating liquids listed in Tables 3 and 4 synthesized by the above-mentioned method are used as raw materials for the insulating film, and spin coating is performed to form 0.7 The insulating film 5 was applied to a thickness of up to 1.1 μm and prebaked by heating at 80 ° C., 150 ° C., and 230 ° C. for 60 seconds in a nitrogen atmosphere.
Then, a curing (curing) treatment in nitrogen was performed at 400 ° C. for 30 minutes to form the insulating film 5. Thus, the semiconductor device 6 provided by the present invention was manufactured. The cross section of the insulating film 5 of the obtained semiconductor device 6 was observed. Evaluation of flatness is shown in FIG.
The tendency was specifically examined using the flatness scale (DOP) shown in FIG. The DOP (%), which is a measure of flatness, was calculated by the following formula. DOP (%) = {1- (θ / 90) (d ₀ / d _m )} ×
100 Here, θ is the inclination of the step of the insulating film 8 caused by the wiring 7 as shown in FIG. 4, d ₀ is the height difference of the insulating film 8, and d _m
Is the thickness of the wiring 7.

The results of the flatness measurement are shown in Tables 3 and 4. It can be seen that excellent flatness can be achieved by using the SOG according to the present invention.

[0082]

[Table 3]

[0083]

[Table 4]

[0084]

As described above in detail, the use of the coating liquid containing the siloxanes, particularly methyl siloxane oligomer, provided by the present invention makes it possible to obtain an insulating film for a semiconductor device having excellent film characteristics, such as an interlayer for an LSI multilayer wiring. An insulating film can be formed. That is, according to the coating solution provided by the present invention and the method for forming an insulating film using the same, an insulating film having excellent film characteristics, that is, uniform flatness of the entire underlayer pattern can be achieved and fine grooves can be completely formed. , Which has excellent crack resistance, can be applied thick enough to flatten the underlying step, and has a low dielectric constant that does not contain water and is advantageous for high-speed wiring, especially An interlayer insulating film for a semiconductor device can be formed.

[Brief description of drawings]

FIG. 1 is a sample A used in Example 1 (see Table 1).
^{29 is} a ²⁹ Si-NMR spectrum of

FIG. 2 is a graph showing the relationship between X defined by formula [2] and the contraction rate, relative permittivity, and water absorption rate of the insulating film in Example 2.

3 (1), (2) and (3) respectively show a wiring layer pattern forming step, a CVD oxide film forming step and an insulating film forming step in the production of an insulating film for a semiconductor device according to the present invention. It is a partial cross-sectional schematic diagram shown.

FIG. 4 is a schematic cross-sectional view of a stepped portion of an insulating film showing a method of obtaining DOP which is a measure of flatness measured in Example 3.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoh Ota             2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo             Saki Steel Co., Ltd. Tokyo head office F-term (reference) 4J035 BA01 BA06 BA11 BA16 CA01K                       EA01 EB10 LB01                 4J038 DL031 KA06 NA21 PB09                       PC03                 5F058 AD05 AF04 AG01 AH02 BA09                       BC02 BD04 BF27 BF46 BH04                       BJ02

Claims (9)

[Claims] 1. A coating liquid for forming an insulating film, which is used for manufacturing a semiconductor device, comprising siloxanes represented by the following formula [1] containing Si atoms bonded to at least one kind of organic substituent, And ²⁹ Si-NMR of the siloxanes
An insulating material having a self-fluidization temperature of 150 ° C. or higher and 300 ° C. or lower satisfying the following formula [2], the content ratio X represented by the following formula [2] being obtained from the integral value of the signal of the spectrum. Coating liquid for film formation. [Chemical 1] In the above formula [1], k, l, m, and n are integers of 0 to 1000. R: at least one organic substituent selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, which may be the same or different, and the phenyl group is a phenyl group having a substituent. But it's okay. The oxygen atom is Si,
Combines with either R or H. [Equation 1] In the above formula [2], Si obtained from A ₀ : ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having no —C bond, A ₁ : ²⁹ Si—Si determined from Si-NMR spectrum
Area of Si signal attributed to Si having one —C bond, A ₂ : Si obtained from ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having two —C bonds, A ₃ : Si obtained from ²⁹ Si-NMR spectrum
The area of the Si signal attributed to Si having three —C bonds is shown. 2. The coating solution for forming an insulating film according to claim 1, wherein k = 0 in the formula [1]. 3. The coating liquid for forming an insulating film according to claim 1, wherein k = 1 and 0 in the formula [1]. 4. The coating liquid for forming an insulating film according to claim 1, wherein the self-fluidization occurs at a lower temperature than the condensation curing. 5. A method for forming an insulating film for a semiconductor device, which comprises using the coating liquid for forming an insulating film according to claim 1. 6. An insulating film-forming coating liquid is applied and then dried,
The insulating film for a semiconductor device according to claim 5, further comprising a step of fluidizing by holding at a temperature of 150 ° C. or more and 300 ° C. or less and further curing at a temperature of 350 ° C. or more and 450 ° C. or less. Forming method. 7. A coating liquid for forming an insulating film used in the manufacture of a semiconductor device, comprising siloxanes represented by the following formula [1] containing Si atoms bonded to at least one kind of organic substituent, And ²⁹ Si-NMR of the siloxanes
A coating solution for forming an insulating film is prepared by using a coating solution for forming an insulating film containing a siloxane having a content ratio X represented by the following formula [2], which is obtained from an integral value of a spectrum signal. After coating, dry it to 150 ℃ or higher 30
It is kept at a temperature of 0 ° C. or lower to be fluidized, and further 350
A method for forming an insulating film for a semiconductor device, which comprises a step of curing at a temperature of ℃ to 450 ° C. [Chemical 2] In the above formula [1], k, l, m, and n: integers from 0 to 1000 are shown. R: at least one organic substituent selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group and a phenyl group, which may be the same or different, and the phenyl group is a phenyl group having a substituent. But it's okay. The oxygen atom is bonded to any of Si, R, and H. [Equation 2] In the above formula [2], Si obtained from A ₀ : ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having no —C bond, A ₁ : ²⁹ Si—Si determined from Si-NMR spectrum
Area of Si signal attributed to Si having one —C bond, A ₂ : Si obtained from ²⁹ Si-NMR spectrum
Area of Si signal assigned to Si having two —C bonds, A ₃ : Si obtained from ²⁹ Si-NMR spectrum
The area of the Si signal attributed to Si having three —C bonds is shown. 8. The method for forming an insulating film for a semiconductor device according to claim 6, wherein the holding at the temperature of 150 ° C. or higher and 300 ° C. or lower is carried out for 30 seconds or longer. 9. The method for forming an insulating film for a semiconductor device according to claim 6, wherein the curing is performed in nitrogen.