JP2001342557A - Method for manufacturing silicon oxide evaporation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicon oxide(SiOx) evaporation film with a porous membrane columnar structure with a low dielectric constant and a high insulation property by an operation at a comparatively low temperature and low vacuum degree, and to provide a method for manufacturing a SiOx evaporation film improved an insulation property and a protecting performance by irradiating an electromagnetic wave and oxidizing the film. SOLUTION: The method for manufacturing the silicon oxide evaporation film is characterized by evaporating SiOx (x value: 0.8-1.4) at 900-1400 deg.C in 10-10000 Pa. The method for manufacturing a silicon oxide evaporation film is further characterized in irradiating an electromagnetic wave of a wavelength of 400 nm or less over the evaporation film of a relative permittivity of 1.5-8.0 manufactured by the above method. A quantity of the electromagnetic irradiation is preferably 0.1 <= irradiation time (time) × irradiance (W/cm2)<=10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a silicon oxide (SiOx) deposited film having a low dielectric constant and a high insulation.

The SiOx deposited film produced according to the present invention can be used, for example, as an interlayer insulating film of a semiconductor device, a gas barrier film of a plastic film, a liquid crystal panel, an antireflection film and the like. Hereinafter, the present invention will be described by taking an interlayer insulating film of a semiconductor device as an example.

[0003]

2. Description of the Related Art In order to increase the degree of integration of a semiconductor device, it is necessary to reduce the distance between metal wirings. However, when the distance between the metal wirings is reduced, the capacitance between the circuits causes signal transmission delay, which hinders high-speed operation. In order to reduce this delay and ensure high speed, it is necessary to reduce the capacity between circuits. That is, it is necessary to lower the relative dielectric constant of the interlayer insulating film.

In order to lower the relative dielectric constant of the interlayer insulating film, a material having a low relative dielectric constant may be used, and silica glass and SiOF are known as typical materials. SiOF is Si
This is intended to reduce the density by terminating the terminal of the -O-Si bond with a fluorine atom.

However, recent advances in semiconductors require a value lower than the relative dielectric constant of silica glass alone. As an improvement, there has been proposed a method of reducing the dielectric constant of the entire film by introducing an air layer by adopting a porous structure.

For example, Japanese Patent Application Laid-Open No. Hei 1-253254 describes a semiconductor device in which metal wirings are formed in multiple layers on a semiconductor substrate on which semiconductor elements are formed via a porous insulating film. There, a mixture of a basic oxide such as sodium oxide and calcium oxide and a mixture of an acidic oxide such as silicon dioxide or a mixture of silicon dioxide and boron oxide is deposited as an insulating film, and then subjected to a heat treatment to form a basic oxide. Alternatively, after depositing only the acidic oxide, only the deposited oxide is eluted to form porosity inside the film.

Japanese Patent Application Laid-Open No. 2000-21245 proposes a method of forming porosity using hollow polymer fine particles and an organic silicon compound.

Japanese Patent Application Laid-Open No. H11-289013 describes a method for forming a porous film by evaporating metallic silicon in an oxygen-containing atmosphere. In this method, the relative dielectric constant shows excellent characteristics of 2 or less. However, as described in paragraph 0052 of the film composition of the present invention, most of the film is SiO ₂ and the content of SiOx is several%. Further, as can be seen from FIG. 15 of the gazette, the film structure is composed of overlapping granular materials. Furthermore, since high-temperature operation of 1500 ° C. or more is required for evaporation of metallic silicon,
There were many things to note about film formation.

[0009] On the other hand, a SiOx deposited film is known for use as an antireflection film and a gas barrier film. In particular, plastics whose gas barrier properties and transparency have been improved by a SiOx vapor-deposited film are easy to check the contents, so that pharmaceuticals,
It is useful for packaging materials such as food. But on the other hand,
Since SiOx has a brownish color tone, there is a demand for improvement.

For example, Japanese Patent Application Laid-Open No. Hei 8-197675 proposes a method of coating a SiOx vapor-deposited film with hydrogen peroxide, and describes that the method is effective in improving oxygen and water vapor permeability. However, the use of hydrogen peroxide requires subsequent cleaning, and it is difficult to completely remove it from a semiconductor device or the like. Further, in Japanese Patent Application Laid-Open No. Hei 8-197675, the light transmittance and oxygen permeability of the SiO film on the plastic film are improved by irradiating light, but the effect is only a few%.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a SiOx deposited film having a low dielectric constant and a high insulation by operating at a relatively low temperature and a low vacuum to form a porous film columnar structure. To provide. Another object of the present invention is to
A SiOx deposited film having a low dielectric constant and a high dielectric constant is formed into a porous film column structure capable of improving insulation and protection performance by irradiating the SiOx deposited film with electromagnetic waves and positively oxidizing a part thereof. Is to provide a method of manufacturing the same.

[0012]

That is, the present invention provides an S
A method for producing a silicon oxide (SiOx) deposited film, characterized by depositing iOx (x value 0.8 to 1.4) at a temperature of 900 to 1400C and a pressure of 10 to 10000 Pa. Also, the present invention is produced by the above method,
A method for producing a silicon oxide (SiOx) vapor-deposited film, characterized in that an SiOx vapor-deposited film having a relative dielectric constant of 1.3 to 8.0 is irradiated with an electromagnetic wave having a wavelength of 400 nm or less. In this case, the irradiation amount of the electromagnetic wave is preferably 0.1 ≦ irradiation time (hour) × irradiation amount (W / cm ² ) ≦ 10.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The SiOx raw material used for the vapor deposition is a powder or a compact containing SiOx and has a specific surface area of 10 m ² /
g or more. The higher the specific surface area, the more preferable it is because the deposition temperature can be lowered to 1400 ° C. or lower, and it is particularly preferable that the specific surface area be 30 m ² / g or more, and more preferably 80 m ² / g or more.

In order to lower the vapor deposition temperature, the X value of SiOx needs to be 1.4 or less, preferably 1.2 or less. The closer the X value is to 1.0, the lower the deposition temperature and the less the deposition residue. However, when the X value is less than 0.8, the deposition rate tends to fluctuate and lacks stability.

[0016] SiOx is may contain a small amount of Si and SiO _2, etc., Si and SiO ₂ may that case preferably contains an equimolar or near. The fact that the oxide is essentially a suboxide of SiOx is important from the viewpoint of vapor deposition stability and operability. In the present invention, Si
Ox raw material is at least 70% or more, preferably 85%
A material containing the above SiOx is used.

In the present invention, Si, SiO ₂ , SiO
As described later, the amount of x and the X value are determined to be mostly amorphous by X-ray diffraction, to obtain a molar ratio by chemically analyzing the amounts of Si and oxygen, and to examine the binding energy of Si2p by XPS. Thus, it can be measured.

As a heating method at the time of vapor deposition, conventional heating means such as resistance heating and electron beam can be used. The vapor deposition temperature needs to be in the range of 900 to 1400 ° C. 90
If the temperature is lower than 0 ° C., the deposition rate is low and productivity is significantly deteriorated. On the other hand, when the temperature is higher than 1400 ° C., it is difficult to form a uniform film, and the blemishes tend to occur. Preferably 950
１３1350 ° C.

The vapor deposition is performed under reduced pressure. In the present invention, a gas is introduced from a high vacuum region to 10 to 10,000.
It is important that the pressure be Pa. At a pressure lower than 10 Pa, the resulting film becomes dense and a film having a low relative dielectric constant cannot be obtained. If the pressure exceeds 10,000 Pa, the film formation rate is slowed down, a long time is required for vapor deposition, and the adhesion of SiOx forming the porosity of the formed film is weakened, and the film becomes brittle. Preferably,
100 to 5000 Pa, more preferably 500
２０００2000 Pa.

In order to adjust the pressure, a mixture of argon and oxygen gas, particularly an argon oxygen ratio (Ar / O ₂ ) of 0.001 to 0.1
It is desirable to introduce a mixed gas of Oxygen gas is required because SiO is oxidized during vapor deposition and the X value is 1.
An object of the present invention is to manufacture a 3-1.8 SiOx film. When the oxygen concentration is high, the X value of SiOx of the formed film exceeds 1.8, or the film cannot form a columnar structure, and the formed film tends to be brittle. On the other hand, when the oxygen concentration is low, the resulting film is a film having an X value equivalent to the raw material SiOx,
The X value of the resulting film is preferably 1.3 or more because the insulating property is slightly inferior.

When a nitrogen gas or a hydrocarbon-based gas is used as a pressure adjusting gas, subcomponents such as nitrides and carbides are generated, which have an effect of increasing the dielectric constant of a formed film.
For other purposes, for example, it may be used for the purpose of increasing the strength of the film, adjusting the structure of the film, or the like.

The temperature of the substrate on which the deposit is deposited may be equal to room temperature, but is preferably lower than 0 ° C. because the columnar structure is easily maintained.

Next, according to the present invention, SiOx
A method for improving insulation of a deposited film will be described.

According to the present invention described above, a low-dielectric-constant film having a porous structure made of a SiOx vapor-deposited film can be obtained, but as it is, permeation of a chemical solution or a corrosive gas from the external environment in a semiconductor manufacturing process. I am concerned. In addition, Si
Increasing the X value of Ox is advantageous for improving insulation. If this is performed by external heating in air, heating at least 700 ° C. or more is required, and high-temperature operation adversely affects the characteristics of the semiconductor device. Furthermore, in the oxidation by the high-temperature operation, the sintering of SiOx starts, the fine voids decrease, the relative dielectric constant of the material itself decreases, and the relative dielectric constant of the film as a whole also decreases because the voids decrease as a whole. is there.

From such a viewpoint, the present inventors have proposed an oxidation method (SiOx) near room temperature while maintaining the columnar structure.
As a result of examining the method of improving the insulation of the film,
When an 8.0 SiOx film is irradiated with an electromagnetic wave having a wavelength of 400 nm or less, it has been found that the upper portion of the film can be densified in a relatively short time, but the X value can be increased while maintaining the porous structure in most other parts. .

The radiated electromagnetic wave preferably has a wavelength of 400 nm or less as a main component, and preferably ultraviolet light or light corresponding to soft X-rays. An electromagnetic wave of more than 400 nm may exist as a sub-component,
In the case of an electromagnetic wave having a main component of visible light, infrared ray or the like exceeding nm, the upper portion of the film becomes denser, but the effect of increasing the X value to the inside is poor.

The irradiation amount of the electromagnetic wave has a wavelength of 400 nm or less.
The amount of light irradiation is, for example, “Thermopile N” manufactured by Eprey.
o17808 "illumination intensity (W /
cm ^Two) And the irradiation time (hour) are 0.1 to 10
It is preferable that the value be Particularly preferably, 0.2 to
8, more preferably 0.5 to 5. The irradiation amount is 0.1
If it is less than 10, the oxidizing effect is poor and a sufficient effect cannot be obtained.
If it exceeds 10, the film is easily peeled from the substrate.

Confirmation of oxidation by electromagnetic wave irradiation can be performed by measuring Si2p binding energy by XPS. In addition, by oxidation by electromagnetic wave irradiation,
Since the film expands in the thickness direction, by comparing the film thickness before and after irradiation, it is possible to know how much oxidation has been performed on the entire film.

【Example】

Examples 1 to 12 Comparative Examples 1 to 4 Prototypes prepared by the gas phase method of Denki Kagaku Kogyo KK were prepared as SiOx powders. The specific surface area of this powder as measured by the BET method was 110 m ² / g. Almost amorphous by X-ray diffraction, Si calculated from analysis of silicon and oxygen
The X value of Ox was 1.05. In the analysis of the powder by fluorescent X-ray, the impurities of the metal were aluminum 2
About 100 ppm and about 100 ppm of Fe.
Ox purity was 99% or more. Furthermore, S by XPS
When the 2p binding energy of i was corrected with carbon and measured, it was 101.5 ev. This powder was formed into a cylindrical shape having a diameter of about 10 mm and a height of about 10 mm using a mold press and CIP. The specific surface area after molding is 103 m ² /
g, and there was almost no change in the specific surface area before and after molding.

The molded pellet is placed in a container of a resistance heating element composed of a composite sintered body of BN and TiB ₂ , heated by energizing the container to evaporate SiOx and deposit a SiOx deposited film on a silicon substrate. Was. The deposition temperature was measured with an infrared radiation thermometer. The pressure in the vapor deposition chamber was controlled by controlling the flow rate of the mixed gas having an adjusted argon / oxygen ratio by adjusting the opening of the exhaust system gate and the gas inflow valve. The pressure in the deposition chamber had a variation of about ± 20% in the range of the deposition time. Further, the silicon substrate was held in a holder in which cooling water was flown in order to avoid heating by vapor deposition.

After the deposition for 10 minutes, the SiOx deposited film was taken out together with the silicon substrate, and the following film properties were measured.
Table 1 shows the results.

(1) The film thickness was measured using an ST step meter manufactured by DEKTAK. (2) The relative permittivity was determined by using a device in which a SiOx vapor deposition film was sandwiched between parallel plate electrodes, measuring the capacitance with an LCZ meter, and calculating the relative permittivity from the electrode area and the film thickness. The measurement was performed at a frequency of 1 MHz. (3) The insulation resistance was measured by measuring the leak current by the DC electric resistance measurement method using the same element as the capacitance measurement. First, the main electrode and the guard electrode are set to the same potential, and a voltage is applied between the main electrode and the counter electrode. If only the leakage current on the main electrode side at this time is read, the measurement can be performed without any influence of the surface current. A leak current was measured when a parallel plate electrode having an area of 0.03 cm ² was applied to the film (element) and a voltage of 20 V was applied. If it is 1 nA or less, it can be said that the film exhibits sufficient insulating properties as an interlayer insulating film. (4) The film structure was obtained by observing the cross section of the film by SEM. Crack peeling and the like were observed with an optical microscope.

With respect to the sample of Example 3, in order to observe the change in the X value of SiOx during the vapor deposition process, S
The surface of the iOx film was etched with argon, and the bonding energy of Si2p inside the film was measured by XPS (Shimadzu Corporation UV-3100 UV-VIS-NR). As a result, the main peak of the binding energy is 102.5 eV
Met.

The Si ₂ P bond energies of Si and SiO ₂ are 99.1 eV and 103.6 eV, respectively. From this value, it is considered that the bond energy when X = 1 of SiOx is considered to be 101.4 eV in the middle. The binding energy 102.5 eV inside the film of No. 3 is SiOx of X = 1.5.
It turned out to be a membrane. Similarly, X values of other SiOx deposited films were measured.

[0035]

[Table 1]

Examples 13 to 20 Reference Examples 1 to 3 Next, experimental examples of electromagnetic wave irradiation on the SiOx film will be described.
explain. Reference Example 1 was at a temperature of 1500 ° C. and a gas pressure during vapor deposition.
Pa, argon oxygen ratio (Ar / O _Two) Under the condition of 0.01
Deposits metal silicon and forms a film on a silicon single crystal substrate
This is one in which a deposited film having a thickness of 350 nm is formed. This membrane
Indicates that the X value is 0.9 and the relative dielectric constant is 8.8, and the SEM observation
Was a dense film.

In Example 13, the Si obtained in Example 1 was used.
In the Ox vapor-deposited film, and in Examples 14 to 20 and Reference Examples 2 and 3, the SiOx vapor-deposited film obtained in Example 3 was 400 nm thick.
The following ultraviolet light (Shiosha's high-pressure mercury lamp "USH-102"
D ”) or visible light (using a commercially available incandescent lamp)
Was irradiated under the conditions shown in Table 2. Irradiation intensity is 0.25W
The distance from the lamp was adjusted using an irradiometer so as to be / cm ² .

The relative dielectric constant, XPS
Observation of X value, film thickness and SEM cross section of SiOx by
The effects of irradiation were investigated. Table 2 shows the results.
In Reference Example 1, cracks occurred in the film surface observation after irradiation. Embodiments 16 and 21 correspond to claim 3.
Is an example deviating from the condition of

[0039]

[Table 2]

[0040]

According to the present invention, a silicon oxide (SiOx) vapor deposited film having a low dielectric constant and a high insulating property can be easily produced by operating at a relatively low temperature and a low vacuum to form a porous film columnar structure. can do. In addition, the SiOx deposited film is irradiated with an electromagnetic wave having a wavelength of 400 nm or less, and a part thereof is positively oxidized, thereby improving insulation and protection performance. A silicon oxide (SiOx) vapor-deposited film can be easily manufactured.

The SiOx deposited film manufactured according to the present invention has a high insulating property and a low relative dielectric constant, and is therefore used as an interlayer insulating film of a semiconductor device.

Further, since the surface layer of the SiOx vapor-deposited film becomes dense and has a low relative dielectric constant, it has a low refractive index, so that it has gas barrier properties and antireflection properties for light, and is a gas barrier film for food packaging materials and the like. It can be used as a surface coat of a liquid crystal panel made of plastics.

Claims (3)

[Claims] 1. The method according to claim 1, wherein the SiOx (x value 0.8 to 1.4) is 90
A method for producing a silicon oxide vapor-deposited film, characterized in that vapor deposition is performed at a temperature of 0 to 1400 ° C. and a pressure of 10 to 10000 Pa. 2. A method for producing a silicon oxide vapor-deposited film, comprising irradiating an electromagnetic wave having a wavelength of 400 nm or less to a vapor-deposited film produced according to claim 1 and having a relative dielectric constant of 1.5 to 8.0. . 3. The method according to claim 2, wherein the irradiation amount of the electromagnetic wave is 0.1 ≦ irradiation time (hour) × irradiation amount (W / cm ² ) ≦ 10. .