JP5607394B2 - Method for forming interlayer insulating film and interlayer insulating film - Google Patents

Description

  The present invention relates to a film forming method using an insulating film material useful as an interlayer insulating film for supporting an LSI wiring structure, and a formed interlayer insulating film. In particular, an interlayer insulating film having a low dielectric constant and good characteristics (in-plane uniformity, leakage current characteristics) to be possessed as an interlayer insulating film can be obtained.

In recent years, the wiring layer has been miniaturized along with the high integration of LSI. However, if a fine wiring layer is used, the influence of signal delay in the wiring layer becomes large, which hinders the increase in signal transmission speed. Has been pointed out. Since this signal delay is proportional to the resistance of the wiring layer and the capacitance between the wiring layers, a reduction in resistance of the wiring layer is required in order to reduce the signal delay.
Therefore, copper having a lower resistivity than conventional aluminum is recently used as a material constituting the wiring layer.

In addition, as the wiring layer becomes finer, the distance between the wirings becomes shorter, so that the wiring interlayer capacitance between adjacent wirings has increased. If this is reduced, the signal delay can be reduced. .
In addition, an interlayer insulating film (also referred to as a barrier film) that separates adjacent copper wirings and suppresses diffusion of copper atoms constituting the wiring layer is formed between the wirings.

  That is, if copper is used as the material constituting the wiring layer and an interlayer insulating film having a low relative dielectric constant and a copper diffusion barrier property (barrier film having a low relative dielectric constant) is formed as the interlayer insulating film, the resistance of the wiring layer is reduced. And the wiring interlayer capacitance can be reduced.

  Examples of the interlayer insulating film having a copper diffusion barrier property include a SiNH film (relative dielectric constant of about 7), a SiCNH film having a nitrogen (N) content of 30% or more (relative dielectric constant of about 3.5 to 6), There is a SiCH film (relative dielectric constant of about 2.7 to 3.5). If these films are arranged in the order of nitrogen content, SiNH> SiCNH> SiCH.

  In order to further reduce the relative dielectric constant of the interlayer insulating film having a copper diffusion barrier property, it is sufficient to increase the carbon (C) content in the insulating film. Uniformity may be deteriorated and leakage current characteristics may be deteriorated.

  This becomes prominent when the carbon content in the interlayer insulating film is 20% or more during XPS measurement. For example, a SiCH film having a carbon content of 20% or more cannot be said to have better in-plane uniformity and leakage current characteristics than a SiCH film having a carbon content of less than 30%. The same can be said for the SiCNH film.

A mechanism that deteriorates the leakage current characteristic is that a dunk ring bond is formed on the Si atom. The electrons on the dangling bonds are chemically active because they are unstable, and particularly have an important influence on the physical properties of the crystal surface (see, for example, Patent Document 1 and Non-Patent Document 1).
Many deteriorations in leakage current characteristics due to atomic defects such as dangling bonds have been observed in SiCNH films, SiCH films, and SiOCH films having a carbon content of 20% or more.

Japanese Patent Laid-Open No. 2002-368084

The 69th JSAP Academic Lecture Performance Proceedings, 2008, p. 720, 4a-CD-2

  By the way, depending on the insulating film material, it is possible to form an interlayer insulating film having a copper diffusion barrier property with a low relative dielectric constant, but depending on the insulating film material, an interlayer insulating film having a deteriorated leakage current characteristic is obtained. There is an inconvenience. In particular, when the carbon content in the interlayer insulating film is 30% or more, there is an inconvenience that the leakage current characteristic that is considered to be caused by atomic defects deteriorates.

Further, when an interlayer insulating film having a copper diffusion barrier property is formed using an isobutyl-based material such as iBTMS (isobutyltrimethylsilane) or DiBDMS (diisobutyldimethylsilane) containing CH ₃ in the structure of the insulating film material, the relative permittivity Can be made smaller than 3.5, but the in-plane uniformity becomes extremely poor.

  Under such circumstances, there has been a demand for an interlayer insulating film having a copper diffusion barrier property with good leakage current characteristics and / or in-plane uniformity while maintaining a low relative dielectric constant. The fact is that is not provided.

化学式（１）において、Ｘ、Ｙ、ＺはＣｎＨｍのいずれかであり、ｎは１〜１０の整数、ｍは１〜２５の整数である。
In order to solve the above problems, the invention according to claim 1 is a method of forming an interlayer insulating film,
An interlayer insulating film characterized by forming an interlayer insulating film by plasma CVD using an insulating film material represented by the following chemical formula (1) and having an isobutyl group on a substrate and a gas containing nitrogen This is a film forming method.

In the chemical formula (1), X, Y, and Z are any of CnHm , n is an integer of 1 to 10, and m is an integer of 1 to 25.

化学式（２）において、Ｘ、Ｙ、ＺはＣｎＨｍのいずれかであり、ｎは１〜１０の整数、ｍは１〜２５の整数である。 The invention according to claim 2 is a method of forming an interlayer insulating film, wherein the interlayer insulating film is formed on the substrate by plasma CVD using an insulating film material represented by the following chemical formula (2) and having an isobutyl group. After the film is formed, a gas containing nitrogen is supplied to the substrate in a heated atmosphere.

In the chemical formula (2), X, Y and Z are any one of CnHm , n is an integer of 1 to 10, and m is an integer of 1 to 25.

  The invention according to claim 3 is the method for forming an insulating film according to claim 1 or 2, wherein the gas containing nitrogen is ammonia gas.

  The invention according to claim 4 is an insulating film formed by the method for forming an insulating film according to any one of claims 1 to 3.

  The invention according to claim 5 is the insulating film according to claim 4, wherein the nitrogen content in the insulating film does not exceed 30%.

  According to the present invention, it is possible to form an interlayer insulating film having a copper diffusion barrier property with good leakage current characteristics and in-plane uniformity while maintaining a low dielectric constant.

FIG. 1 is a schematic configuration diagram showing an example of a film forming apparatus used in an embodiment of the present invention. FIG. 2 is a graph showing the relationship between the relative dielectric constant and the leakage current when iBTMS is used as the insulating film material and the amount of ammonia is changed. FIG. 3 is a graph showing the relationship between the relative dielectric constant and the leakage current when DiBDMS is used as the insulating film material and the amount of ammonia is changed. FIG. 4 is a graph showing the relationship between the relative dielectric constant and the leakage current when 4MS is used as the insulating film material and the amount of ammonia is changed.

[First Embodiment]
Hereinafter, a method for forming an interlayer insulating film and an interlayer insulating film according to a first embodiment to which the present invention is applied will be described.

<Insulating film material>
First, the insulating film material used in this embodiment will be described. The insulating film material of this embodiment is a compound represented by the above chemical formula (1), a known compound containing CH ₃ in its structure, and can be obtained by a known synthesis method.
However, a method for forming an interlayer insulating film using these compounds so as to have a low relative dielectric constant, uniform in-plane and good leakage current characteristics has not been known.

  The insulating film material may be any compound as long as it is a compound represented by the above chemical formula (1), but iBTMS, DiBDMS, TiBMS (triisobutylmethylsilane) are particularly suitable for the present embodiment. ) And a compound having an isobutyl group in its structure. Also suitable are compounds such as 4MS (tetramethylsilane), 3MS (trimethylsilane), and 2MS (dimethylsilane).

iBTMS is a compound represented by X = CH ₃ , Y = CH ₃ , Z = isoC ₄ H ₉ in the chemical formula (1). DiBDMS is a compound represented by X = CH ₃ , Y = isoC ₄ H ₉ , Z = isoC ₄ H ₉ in the chemical formula (1). TiBMS is a compound represented by X = isoC ₄ H ₉ , Y = isoC ₄ H ₉ , Z = isoC ₄ H ₉ in the chemical formula (1).
4MS is a compound represented by X = CH ₃ , Y = CH ₃ , and Z = CH ₃ in the chemical formula (1). 3MS is a compound represented by X = CH ₃ , Y = CH ₃ , and Z = H in the chemical formula (1). 2MS is a compound represented by X = CH ₃ , Y = H, Z = H in the chemical formula (1).

<Method for forming interlayer insulating film>
Next, a method for forming an interlayer insulating film according to this embodiment will be described.
The interlayer insulating film forming method of the present embodiment is basically performed by a plasma CVD method using an insulating film material represented by the above chemical formula (1) on a substrate such as a silicon wafer and a gas containing nitrogen. In this method, an interlayer insulating film is formed.

  As the insulating film material, the compound represented by the chemical formula (1) can be used alone, or two or more kinds of compounds can be mixed and used. When two or more kinds of compounds are mixed and used, they may be mixed at an appropriate mixing ratio in consideration of the relative dielectric constant, in-plane uniformity and leakage current characteristics of the obtained interlayer insulating film.

  Moreover, it is preferable to use the compound selected from iBTMS, DiBDMS, TiBMS, 4MS, 3MS, or 2MS, even if it is 1 type or 2 types or more.

The mixing ratio of the insulating film material and the nitrogen-containing gas may be set as appropriate in consideration of the relative dielectric constant, in-plane uniformity, and leakage current characteristics of the obtained interlayer insulating film.
The nitrogen-containing gas is preferably ammonia gas, but is not limited thereto. Further, the purity of the gas containing nitrogen is not particularly limited.

The flow rate of the nitrogen-containing gas is preferably designed so that the nitrogen content in the deposited interlayer insulating film is 0.02% or more and 30% or less.
Here, the nitrogen content in the insulating film can be calculated by the following formula (1) from the peak wave number of SiH from an absorption spectrum that can be obtained by a Fourier transform infrared spectrometer.

  Note that the SiH peak wave number is a wave number at which the absorption spectrum becomes maximum at 2000 (1 / cm) to 2400 (1 / cm). Further, the peak wave number of SiH is shifted by atoms bonded to Si atoms. For example, when 4 bonds of Si atoms are 2 N atoms, 1 is a C atom, 1 is an H atom and 3 are a C atom and 1 is an H atom, N As the number of atoms increases, the peak position of SiH shifts to the higher wavenumber side.

The insulating film material and nitrogen-containing gas can be used as they are if they are gaseous at room temperature, and if they are liquid, they can be vaporized by bubbling using an inert gas such as helium, vaporized by a vaporizer, Alternatively, it is used after being gasified by vaporization by heating.
The insulating film material and the nitrogen-containing gas desirably have a boiling point of 300 ° C. or less at 1 atmosphere.

As the plasma CVD method itself, a well-known one can be used. For example, a film can be formed using a parallel plate type film forming apparatus 1 as shown in FIG.
The plasma film forming apparatus 1 shown in FIG. 1 includes a chamber 2 that can be depressurized. The chamber 2 is connected to an exhaust pump 5 through an exhaust pipe 3 and an on-off valve 4. The chamber 2 is provided with a pressure gauge (not shown) so that the pressure in the chamber 2 can be measured. In the chamber 2, a pair of flat plate-like upper electrode 6 and lower electrode 7 that are opposed to each other are provided. The upper electrode 6 is connected to a high frequency power source 8 so that a high frequency current is applied to the upper electrode 6.

The lower electrode 7 also serves as a mounting table on which the substrate 9 is mounted. A heater 10 is built in the lower electrode 7 so that the substrate can be heated.
In addition, a gas supply pipe 11 is connected to the upper electrode 6. A film-forming gas supply source (not shown) is connected to the gas supply pipe 11 and a film-forming gas is supplied from the film-forming gas supply device. It flows out through the through-holes while diffusing toward the lower electrode 7.

The film forming gas supply source includes a vaporizer for vaporizing the insulating film material and a flow rate adjusting valve for adjusting the flow rate, and a supply device for supplying a carrier gas. The gas flows through the gas supply pipe 11 and flows out from the upper electrode 6 into the chamber 2.
The substrate 9 is placed on the lower electrode 7 in the chamber 2 of the plasma film forming apparatus, and the film forming gas is sent into the chamber 2 from a film forming gas supply source. A high frequency current is applied to the upper electrode 6 from the high frequency power source 8 to generate plasma in the chamber 2. As a result, an insulating film generated by the gas phase chemical reaction from the film forming gas is formed on the substrate 9.
The substrate 9 is mainly made of a silicon wafer, but other insulating films, conductive films, wiring structures, etc. may be formed on the silicon wafer in advance.

  As the plasma CVD method, in addition to the parallel plate type, ICP plasma, ECR plasma, magnetron plasma, high frequency plasma, microwave plasma, capacitively coupled plasma, inductively coupled plasma, etc. can be used. It is also possible to use a two-frequency excitation plasma that introduces a high frequency to the lower electrode.

The film forming conditions in this plasma film forming apparatus are preferably in the following range, but are not limited thereto.
Insulating film material flow rate: 5 to 200 cc / min.
Flow rate of nitrogen-containing gas: 0 to 200 cc / min Pressure: 0.2 Pa to 5000 Pa
RF power: 30 to 2000 W, preferably 50 to 700 W
LF power: 0 to 1000 W, preferably 0 to 200 W
Substrate temperature: 500 ° C. or less Reaction time: about 60 seconds (may be any time)
Deposition thickness: 5 nm to 800 nm

  Note that helium may be circulated during film formation. At that time, the flow rate of helium is in the range of 0 to 3000 sccm, preferably in the range of 0 to 1000 sccm with respect to 1 sccm of the raw material, preferably in relation to the raw material (insulating film material and nitrogen-containing gas) and helium. It is preferable to set.

  Moreover, in the film-forming conditions, a preferable substrate temperature is in the range of 150 to 380 ° C. In order to reduce the relative dielectric constant of the insulating film, about 300 ° C. (270 to 300 ° C.) is good, and in order to improve the in-plane uniformity and leakage current characteristics, about 350 ° C. (300 to 380 ° C.) is good. It can be set to an appropriate temperature within this range according to the desired physical properties.

<Interlayer insulation film>
Next, the interlayer insulating film of this embodiment will be described.
The interlayer insulating film of the present embodiment is formed by a plasma CVD reaction using a plasma film forming apparatus using the above-described plasma CVD insulating film material and a nitrogen-containing gas.
The interlayer insulating film preferably has a nitrogen content of 0.02% to 30%. If the nitrogen content is less than 0.02%, the in-plane uniformity and leakage current characteristics cannot be improved, and if it exceeds 30%, the relative dielectric constant increases, which is inconvenient.

  The interlayer insulating film obtained by the interlayer insulating film forming method of this embodiment has a low relative dielectric constant of about 3.5, and has excellent in-plane uniformity and leakage current characteristics. The reason for having such characteristics is unclear, but is presumed as follows.

<Leakage current characteristics>
The interlayer insulating film of this embodiment is formed by a plasma CVD reaction using an insulating film material and a nitrogen-containing gas (ammonia gas). It is considered that the generation of dangling bonds that are likely to be formed in the vicinity of carbon atoms or Si atoms is suppressed, and the current leakage path is reduced.

  The cause of the deterioration of the leakage current characteristic is the presence of dangling bonds in the interlayer insulating film. That is, since current flows through the dangling bond as a path, the leakage current characteristic is deteriorated. In the present embodiment, since a film containing nitrogen-containing gas is added, the formation of dangling bonds can be suppressed.

In addition, when a dangling bond is formed, the dangling bond tends to remain in the interlayer insulating film in a situation where only SiCH exists in the chamber or a situation where H does not exist sufficiently in the chamber.
However, if a gas containing nitrogen is present in the chamber, Si in the interlayer insulating film and H or N of the gas containing nitrogen are bonded to form a SiH bond or a SiN bond, thereby forming a dangling bond. It will be resolved.

  As described above, since the generation of dangling bonds is suppressed, the leakage current characteristics are improved. Further, when left in the air with dangling bonds formed in the interlayer insulating film, moisture in the air may adhere to the surface of the interlayer insulating film and form SiOH bonds. Suppressing the generation of dangling bonds also improves the stability of the interlayer insulating film in air.

<In-plane uniformity>
When an isobutyl-based material such as iBTMS or DiBDMS containing CH ₃ is used, for example, when a film having a low dielectric constant such as a relative dielectric constant of less than 3.5 is formed, on the substrate (wafer) surface and in the substrate surface The reaction does not progress uniformly. This is said to have poor in-plane uniformity. If the in-plane uniformity is poor, the thickness of the formed interlayer insulating film is not uniform, and for example, a difference of 3% or more may occur between the maximum thickness and the minimum thickness.

This occurs in order to suppress the RF power of the film forming apparatus for the purpose of selectively cutting the bond. That is, the selectively cleaved bond is a Cα-Cβ bond of isobutyl bond, and this phenomenon occurs because the film is formed by specifically cleaving this bond to increase the Si—CH ₂ —Si bond. It is. At this time, since SiCH ₃ is a relatively stable bond as compared with the isobutyl bond, it is not cut in the plasma and is taken into the insulating film as SiCH ₃ , but the reaction becomes local, and one on the substrate. The reaction concentrates on the part and the in-plane uniformity decreases.
However, by adding a nitrogen-containing gas, Si—CH ₃ and N react to form SiNH ₃ , and a SiNHSi bond is easily formed. Accordingly, the reaction occurs across the entire substrate, and the in-plane uniformity is improved.

<About reduction of relative permittivity>
As described above, as SiNHSi crosslinking is easily formed in the presence of SiH bonds and SiN bonds in suppressing the generation of dangling bonds and, in particular SiCH 2 _Si bond in the case of using isobutyl-based material Since film formation is performed so as to increase, as a result, a relatively large amount of SiCH ₃ remains in the interlayer insulating film. For this reason, the density of the interlayer insulating film is lowered and the relative dielectric constant is reduced.

  From the above, it is considered that the interlayer insulating film of this embodiment becomes an interlayer insulating film having a low relative dielectric constant, excellent leakage current characteristics, and in-plane uniformity.

[Second Embodiment]
Next, an interlayer insulating film forming method and an interlayer insulating film according to a second embodiment of the present invention will be described. In addition, this embodiment is a modification of 1st Embodiment, and abbreviate | omits description about the same part.

  The insulating film material used in this embodiment is the same as that in the first embodiment. In this embodiment, unlike the first embodiment, after the insulating film material represented by the chemical formula (1) is formed by the plasma CVD method, a gas containing nitrogen is supplied onto the substrate in a heated atmosphere. An interlayer insulating film is formed.

Specifically, after an insulating film material is formed on the substrate by a plasma CVD method, a mixed gas of an inert gas and ammonia gas is circulated through the film forming apparatus, and the substrate is heated to form an insulating film. The heat treatment is performed.
Nitrogen can be used as the inert gas, for example, and the heat treatment is performed at a substrate temperature of, for example, about 350 ° C.

  Also in this embodiment, an interlayer insulating film having a low relative dielectric constant and excellent leakage current characteristics and in-plane uniformity can be formed as in the first embodiment.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
However, the present invention is not limited to the following examples.

Example 1
First, in Example 1, an 8 inch (200 mm diameter) silicon wafer (substrate) was placed on a susceptor heated to about 350 ° C. in advance using a parallel plate type capacitively coupled plasma CVD apparatus as shown in FIG. Transported, isobutyltrimethylsilane (iBTMS) as an insulating film material gas was circulated at a volume flow rate of 30 cc / min and nitrogen-containing gas was circulated at a volume flow rate of 30 cc / min, and the output (RF power) of the high frequency power supply for plasma generation was set to 700 W Then, the output (LF power) of the low frequency power source for plasma generation was set to 0 W, and an interlayer insulating film was formed. At this time, the pressure in the chamber of the plasma CVD apparatus was 4 torr.
Note that the ammonia circulation amount is determined so that the nitrogen content ratio calculated by using the above formula (1) in the formed interlayer insulating film is less than 30%.

  In order to measure the relative dielectric constant of the obtained interlayer insulating film, the silicon wafer was transferred onto a CV measuring apparatus manufactured by SSM, and the relative dielectric constant of the interlayer insulating film was measured using a mercury electrode. showed that. The results are shown in Table 1.

In addition, in order to measure the leakage current of the obtained interlayer insulating film, the silicon wafer is transferred onto a CV measuring device manufactured by SSM, and the leakage current characteristic (voltage current characteristic) of the interlayer insulating film is measured using a mercury electrode. It was measured. Whether the leakage current characteristic is good or bad can be determined that the leakage current characteristic is good when the applied voltage is 1 MV / cm and the leakage current is low. As a result of the measurement, the leakage current was 6.4 × 10 ⁻¹⁰ A / cm ² when the applied voltage was 1 MV / cm. The results are shown in Table 1.

  In addition, about the carbon content rate and nitrogen content rate of the obtained interlayer insulation film, it analyzes with a FT-IR apparatus, and uses the Fourier transform for the wavelength of carbon with respect to infrared light and the wavelength of nitrogen with respect to infrared light. By examining the intensity distribution. As a result of the measurement, it was confirmed by the above formula (1) that 11.7% of nitrogen was contained. The results are shown in Table 1.

  Further, the in-plane uniformity of the obtained interlayer insulating film was measured. Specifically, the film thickness of 9 points or 18 points was measured, and the quality was judged based on the value obtained by the following mathematical formula (2). The results are shown in Table 1.

(Example 2)
Next, in Example 2, diisobutyldimethylsilane (DiBDMS) as an insulating film material is circulated at a volume flow rate of 30 cc / min and ammonia as a nitrogen-containing gas is circulated at a volume flow rate of 30 cc / min. An interlayer insulating film was formed by setting. At this time, the pressure in the chamber of the plasma CVD apparatus was 3 torr. Other conditions are the same as in the first embodiment.

  Table 1 shows the measurement and evaluation results of the relative dielectric constant, leakage current characteristics, carbon content ratio, nitrogen content ratio, and in-plane uniformity of the obtained interlayer insulating film.

(Comparative Example 1)
Next, as Comparative Example 1, an interlayer insulating film was formed by circulating isobutyltrimethylsilane (iBTMS) as an insulating film material at a volume flow rate of 30 cc / min. At this time, the pressure in the chamber of the plasma CVD apparatus was 3 torr. Other conditions are the same as in the first embodiment.

  Table 1 shows the measurement and evaluation results of the relative dielectric constant, leakage current characteristics, carbon content ratio, nitrogen content ratio, and in-plane uniformity of the obtained interlayer insulating film. The leakage current characteristics are shown in FIG.

(Comparative Example 2)
Next, as Comparative Example 2, an interlayer insulating film was formed by flowing diisobutyldimethylsilane (DiBDMS) as an insulating film material at a volume flow rate of 30 cc / min. Other conditions are the same as in Example 2.

  Table 1 shows the measurement and evaluation results of the relative dielectric constant, leakage current characteristics, carbon content ratio, nitrogen content ratio, and in-plane uniformity of the obtained interlayer insulating film.

  From the results shown in Table 1, the interlayer dielectric film formed in Example 1 has a relative dielectric constant of 3.22, whereas the interlayer dielectric film formed in Comparative Example 1 has a relative dielectric constant of 3 It was found that the leakage current characteristic was improved by entraining ammonia.

  From the results shown in Table 1, the interlayer dielectric film formed in Example 2 has a relative dielectric constant of 3.36, whereas the interlayer dielectric film formed in Comparative Example 2 has a relative dielectric constant. It was found that the leakage current characteristic was improved while keeping the relative dielectric constant low by bringing ammonia together.

(Examples 3 to 5)
Next, in Example 3, when isobutyltrimethylsilane (iBTMS) is used as the insulating film material, ammonia is selected as the nitrogen-containing gas, and the film is formed by the plasma CVD method for each ratio of the nitrogen-containing gas to the insulating film material. The leakage current and relative dielectric constant were investigated. The results are shown in Table 2 and FIG. In FIG. 2, the vertical axis represents the leakage current characteristics (leakage current A / cm ² when the electric field is 1 MV / cm), the horizontal axis represents the relative dielectric constant, the parameter is the amount of ammonia, and the parameter is relative to the insulating film material. Represents a percentage.

  Similarly, in Example 4, diisobutyldimethylsilane (DiBDMS) is used as the insulating film material, and in Example 5, the leakage current when the film is formed by plasma CVD using tetramethylsilane (4MS) as the insulating film material. And the relative dielectric constant was investigated. The results are shown in Table 3, Table 4, FIG. 3, and FIG.

  From FIG. 2, when iBTMS is used as the insulating film material, it can be determined that the relative permittivity is low and the ammonia accompanying amount is appropriate when the ammonia accompanying amount is 0.2 to 11% with respect to the insulating film material. .

  From FIG. 3, when DiBDMS is used as the insulating film material, it can be determined that when the ammonia entrainment amount is 0.2 to 10% with respect to the insulating film material, the relative dielectric constant is low and the ammonia entrainment amount is appropriate. .

  From FIG. 4, when 4MS is used as the insulating film material, it can be determined that when the ammonia entrainment amount is 0.02 to 15% with respect to the insulating film material, the relative dielectric constant is low and the ammonia entrainment amount is appropriate. .

(Example 6)
Next, in Example 6, when ammonia was selected as the nitrogen-containing gas, the ratio of the nitrogen-containing gas to the insulating film material was set in the range of 0.02% to 15%, and the film was formed by plasma CVD. The amount of nitrogen in the film, the relative permittivity, and the leakage current were examined. The results are shown in Table 5. The material selected as the insulating film material, the pressure, the power density, the flow rate of the insulating film material, and the flow rate of ammonia were the conditions shown in Table 5.

(Comparative Example 3)
In Comparative Example 3, the amount of nitrogen in the film, the relative permittivity, and the leakage current when the film was formed by the plasma CVD method without using a nitrogen-containing gas were examined. The results are shown in Table 6. The material selected as the insulating film material, the pressure, the power density, the flow rate of the insulating film material, and the flow rate of ammonia were the conditions shown in Table 6.

  From Tables 5 and 6, it can be seen that by adding ammonia to the insulating film material and forming a film, the leakage current characteristics are improved while the dielectric constant is kept low.

  As described above, when an interlayer insulating film is formed by a plasma CVD method using the insulating film material represented by the chemical formula (1), the interlayer has a low relative dielectric constant and good leakage current characteristics and in-plane uniformity. An insulating film can be obtained.

  The present invention can be applied to a semiconductor device using highly integrated LSI wiring required for the next generation.

DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus, 2 ... Chamber, 3 ... Exhaust pipe, 4 ... On-off valve, 5 ... Exhaust pump, 6 ... Upper electrode, 7 ... Lower electrode, 8 ... High frequency power supply, 9 ... Substrate, 10 ... Heater, 11 ... Gas supply piping

Claims (5)

A method for forming an interlayer insulating film, comprising:
An interlayer insulating film characterized by forming an interlayer insulating film by plasma CVD using an insulating film material represented by the following chemical formula (1) and having an isobutyl group on a substrate and a gas containing nitrogen A film forming method.

In the chemical formula (1), X, Y, and Z are any of CnHm , n is an integer of 1 to 10, and m is an integer of 1 to 25. A method for forming an interlayer insulating film, comprising:
After an interlayer insulating film is formed by plasma CVD using an insulating film material represented by the following chemical formula (2) and having an isobutyl group on the substrate, a gas containing nitrogen is supplied to the substrate in a heated atmosphere. A method for forming an interlayer insulating film characterized by the above.

In the chemical formula (2), X, Y and Z are any one of CnHm , n is an integer of 1 to 10, and m is an integer of 1 to 25.   The method for forming an interlayer insulating film according to claim 1, wherein the nitrogen-containing gas is ammonia gas.   The interlayer insulation film formed by the film-forming method of the interlayer insulation film of any one of Claim 1 thru | or 3.   The interlayer insulating film according to claim 4, wherein a nitrogen content in the interlayer insulating film is 0.02% or more and 30% or less.

Images