JPH06333919A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To suppress the generation of particles so as to improve the quality, yield and flattening characteristic of an Si oxide film containing a specific amount of fluorine by forming the Si oxide film by a plasma CVD method using a silicon compound gas containing fluorine and O2 or N2O. CONSTITUTION:The device is provided with an Si oxide film 24 formed by a plasma CVD method using a silicon compound gas containing fluorine and O2 or N2O and containing fluorine by 0.1-20at.%. For example, a first Si oxide film 23 containing no fluorine is formed to a thickness of 1,000Angstrom on the surface of a sample having Al wiring 22 on the surface of a substrate 21 by using an SiH4 gas, Ar gas, and O2 gas. After the film 23, a second Si oxide film 24 is deposited to a nearly flat surface on the surface of the film 23 by using an SiF4 gas, Ar gas, and O2 gas. Therefore, the film 24 can be formed of the SiF4 without causing any reaction between the SiF4 and Al wiring 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a Si oxide film formed by a plasma CVD method using silicon fluoride gas and a method for manufacturing the same.

[0002]

2. Description of the Related Art Insulating films used in LSIs and VLSIs include capacitor insulating films, interlayer insulating films, and passivation films. These inner interlayer insulating films are SiH ₄ ,
It is often formed by a plasma CVD method using O ₂ or N ₂ O. This is because the plasma CVD method is unlikely to cause defects such as pinholes and cracks in the insulating film.

[0003]

However, SiH
₄ has a strong reactivity with O ₂ or N ₂ O, and reacts explosively only when mixed. When activated by plasma, the reaction is more likely to occur, and when a Si oxide film is formed by the plasma CVD method, the reactant is deposited on a portion other than the semiconductor such as the inner wall of the chamber where the Si oxide film is formed. . There is a problem in that the deposit causes particles to be generated and deteriorates the quality of the semiconductor device. Also,
In order to prevent particles, it is necessary to frequently clean the inside of the chamber, which causes a problem that the operating rate of the apparatus is deteriorated and the yield of semiconductor manufacturing is reduced.

In order to solve this, a method of forming a Si oxide film by using a silicon fluoride gas having a reactivity lower than that of SiH ₄ has been considered (J. Appl. Phys. 64 (8), 15).
Oct.1988). This method uses Si ₂ F ₆ as a raw material gas,
A film is formed by a photo CVD method using O ₂ and Si ₂ H ₆ . As a result, the reactivity becomes slightly weaker and the amount of reactants attached to the inner wall of the chamber is reduced. However, since Si ₂ F ₆ and O ₂ alone do not form a film, Si ₂ H ₆ having high reactivity must be used. However, there was a problem that a strong reaction still occurred.

Further, the flattening property is important for forming the interlayer insulating film, but when the interlayer insulating film is formed so as to cover a fine pattern of 0.5 μm or less between wirings, a void, that is, an edge portion of the wiring is formed. There has been a problem that the deposited insulating film covers the space between the wirings, and the insulating film does not sufficiently enter between the wirings to cause a defect such as a space, thereby reducing the planarization characteristic.

Further, in recent years, particularly for the purpose of speeding up the LSI, in order to reduce the time constant of the signal transmitted through the Al wiring, an Si oxide film having a low relative dielectric constant is formed on the interlayer insulating film and the passivation film of the Al wiring. Is required to be used. SiH ₄ and O ₂ , SiH ₄ and N ₂ O, or T
A conventional photo-CVD method using EOS, O _3, O _2, etc.,
Oxide film CVD such as thermal CVD method and plasma CVD method
Method, the relative permittivity of Si oxide film becomes 3.8 or more,
It was a factor that hinders the speedup of I. The value of the relative dielectric constant depends on the content of OH groups during the oxidation of Si, and since the content of OH groups is large in the Si oxide film, the relative dielectric constant has a large value.

Further, a silicon oxide film containing fluorine has been proposed by a thermal CVD method using a source gas containing alkoxyfluorosilane as a main component (Japanese Patent Laid-Open No. 4-239750).
Issue). The relative permittivity of this film is 3.7, which is 1
The decrease is less than a percent. This relative permittivity varies depending on the film forming temperature, but since this film contains OH groups, there is a problem that reliability is low when used as an interlayer insulating film.

Further, the gate insulating film of the insulated gate field effect transistor is formed of dichlorosilane (SiH ₂ Cl ₂ )
It has been proposed to form by a plasma CVD method using a monosilane derivative gas containing chlorine or a monosilane derivative gas containing fluorine (JP-A-3-36767). However, the contents of this proposal are aimed at improving the dielectric strength and reducing the interface state density, which have been problems of the conventional thermal oxidation method or CVD method in forming a Si oxide film on polycrystalline silicon. By increasing the ratio of monosilane derivative gas containing elements such as chlorine or fluorine or hydrogen chloride during film formation, a natural oxide film on the silicon layer,
It is intended to form a film while removing contaminants such as organic substances and metals, and there is no description of a Si oxide film containing fluorine.

On the contrary, when a mixture of monosilane derivative gas containing elements such as chlorine or fluorine or hydrogen chloride and monosilane is used, the ratio of the monosilane gas is increased so that chlorine or It is described that the amount of fluorine is reduced and a high-quality oxide film having a high withstand voltage is formed, which suggests that it is not preferable to contain chlorine or fluorine.

The present invention has been made in view of the above circumstances. By forming a Si oxide film by a plasma CVD method using a silicon compound gas containing fluorine, generation of particles is suppressed and quality and yield are improved. S as an interlayer insulating film or a passivation film.
An object of the present invention is to provide a semiconductor device capable of improving the planarization characteristic of the i oxide film and further increasing the speed of signal transmission, and a method of manufacturing the same.

[0011]

A semiconductor device according to a first aspect of the present invention.
The device is a silicon compound gas containing fluorine and O.₂Or N ₂
0.1 to 0.1 formed by the plasma CVD method using O and
Provide a Si oxide film containing 20 atomic% of fluorine 6.
Characterize.

A semiconductor device according to a second invention is characterized in that, in the first invention, the Si oxide film is formed between adjacent wirings.

A semiconductor device according to a third invention contains fluorine.
Silicon compound gas and O₂Or N ₂Plastic using O and
The relative dielectric constant of 3.7 to 2.9 formed by the Zuma CVD method
It is characterized in that it is provided with a Si oxide film.

A semiconductor device according to a fourth invention is characterized in that, in the first or third invention, the Si oxide film is an interlayer insulating film.

A semiconductor device according to a fifth invention is characterized in that, in the first or third invention, the Si oxide film is a passivation film.

A method of manufacturing a semiconductor device according to a sixth aspect of the invention is
It is characterized in that a Si oxide film is formed by a plasma CVD method using a fluorine-containing silicon compound gas and O ₂ or N ₂ O.

A method of manufacturing a semiconductor device according to the seventh invention is
A step of forming a first Si oxide film by a plasma CVD method using a fluorine-free silicon compound gas and O ₂ or N ₂ O; and a fluorine-containing silicon compound gas and O ₂ or N ₂ O. And a step of depositing a second Si oxide film on the first Si oxide film.

A method of manufacturing a semiconductor device according to the eighth invention is
A step of forming a second Si oxide film using a silicon compound gas containing fluorine and O ₂ or N ₂ O by a plasma CVD method; and a silicon compound gas containing no fluorine and O ₂ or N ₂ O. And a step of depositing a first Si oxide film on the second Si oxide film.

A method of manufacturing a semiconductor device according to a ninth aspect of the invention is
A step of forming a first Si oxide film by a plasma CVD method using a fluorine-free silicon compound gas and O ₂ or N ₂ O; and a fluorine-containing silicon compound gas and O ₂ or N ₂ O. Using the step of depositing a second Si oxide film on the first Si oxide film, and the second Si oxide film using a fluorine-free silicon compound gas and O ₂ or N ₂ O. And a step of forming a third Si oxide film thereon.

A method of manufacturing a semiconductor device according to the tenth invention
In the sixth, seventh, eighth or ninth invention,
By applying an electric potential, a silicon compound gas containing fluorine and O₂
Or N ₂A special feature is that the plasma CVD method using O and
To collect.

[0021]

In the semiconductor device and the method of manufacturing the same according to the present invention, the plasma CVD method is performed using the silicon compound gas containing fluorine and O ₂ or N ₂ O, so that the Si oxide film can be reacted more gently than before. Is formed as an insulating film such as an interlayer insulating film or a passivation film. Therefore, the reaction does not proceed except in the plasma generating part, the adhesion of the reactant to the wall surface of the apparatus is reduced, and the generation of particles is reduced. The Si oxide film deposited in this way is OH
0.1-20 atomic% with little or no group content
Since it contains fluorine and has a relative dielectric constant of 3.7 to 2.9, the signal transmission of the semiconductor device can be speeded up. Further, when the signal transmission speed of the semiconductor device is set to the same level as in the related art, the film thickness of the Si oxide film can be made thinner than in the related art. Further, since the fluorine-based film-forming species that are formed in plasma easily cause migration, the coverage of the recesses on the substrate surface is improved.

Further, in the semiconductor device of the present invention, since the Si oxide film containing 0.1 to 20 atomic% of fluorine is formed between the adjacent wirings, the increase of the wiring capacitance in the same layer is suppressed.

Furthermore, in the method of manufacturing a semiconductor device of the present invention, the reactivity of the first Si oxide film, for example, with fluorine, by the plasma CVD method using SiH ₄ and O ₂ or SiH ₄ and N ₂ O is used. And a silicon compound gas containing fluorine and O.
₂ or N ₂ O is used to deposit a second Si oxide film containing fluorine. Further, for example, a second Si oxide film is deposited using a silicon compound gas containing fluorine, and then Si
A first Si oxide film is deposited using H ₄ . Further, a second Si oxide film containing fluorine is deposited on the formed first Si oxide film, and a third S that does not contain fluorine is further deposited thereon.
Deposit i oxide film. The first and third Si oxide films prevent a substance such as aluminum wiring having reactivity with fluorine from being corroded by the reaction with fluorine.

Furthermore, in the method for manufacturing a semiconductor device of the present invention, a negative potential is applied to the substrate to form the film while performing the sputter etching on the unevenness of the substrate surface, so that the Si oxide film having a low relative dielectric constant is formed on the uneven surface. To reduce the level difference and deposit with good flatness.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic vertical sectional view showing the structure of an ECR plasma CVD apparatus used for implementing the present invention.
In the figure, 1 is a plasma generation chamber, which is formed in a hollow cylindrical shape. A circular microwave inlet 1 in the upper center
b, a cylindrical microwave waveguide 3 has one end connected to a microwave oscillator (not shown), and the other end has a flange 3
a is provided and is connected to the microwave introduction port 1b. The microwave introduction port 1b is provided with a microwave introduction window 1a made of a quartz glass plate so as to close the microwave introduction port 1b. Further, around the plasma generating chamber 1, an exciting coil 4 is arranged concentrically with one end of a microwave waveguide 3 connected to the plasma generating chamber 1 so as to surround them, and the exciting coil 4 is not shown. Connected to DC power supply. A gas introduction system 6 is opened on the upper wall of the plasma generation chamber 1.

In the center of the lower wall of the plasma generation chamber 1, a plasma extraction window 1 is provided at a position facing the microwave introduction port 1b.
The reaction chamber 2 is formed so as to face the plasma extraction window 1c. The plasma extraction window 1c is provided in the reaction chamber 2.
A sample table 5 is arranged at a position facing the
Are to be placed. A gas introduction system 7 is opened on the side wall of the reaction chamber 2, and an exhaust system 8 connected to an exhaust device (not shown) is opened on the lower wall.

Using the above-mentioned apparatus, Si acid was added on the sample S.
When forming a chemical film, first set the temperature of the sample table 5 to 300
℃, the inside of the plasma generation chamber 1 and reaction chamber 2 by the exhaust system 8
1 x 10 ^-6Pressure less than Torr, 30 sc from gas introduction system 7
cm SiF_Four, Into the reaction chamber 2 to supply the gas introduction system 6
To 43 sccm Ar, 70 sccm O₂Inside the plasma generation chamber 1
Supply to. Then, the reaction chamber 2 is pressurized to a predetermined pressure, for example,
2 x 10^-3Torr. And the microwave of output 2.8kW
From a microwave oscillator (not shown) to a microwave waveguide.
3, Inside the plasma generation chamber 1 through the microwave introduction window 1a
Is introduced into the plasma generation chamber by the exciting coil 4.
A magnetic field is generated in 1. This makes the plasma generation chamber
The ECR condition is satisfied in 1 and the
Ar, O supplied₂Gas is decomposed and plasma is generated
It The generated plasma is generated in the reaction chamber 2 by the magnetic field.
Introduced to SiF_FourThe gas is activated to move the gas to the surface of the sample S.
A Si oxide film containing nitrogen is formed.

The semiconductor device of the first embodiment formed by the above manufacturing method will be described below. FIG. 2 is an infrared absorption spectrum of the above Si oxide film. As is clear from the figure, absorption due to the Si—F bond was observed at 940 cm ^−1, and it was found that fluorine was incorporated in the Si oxide film. Further, it is known that absorption due to Si—OH bond appears near 3600 cm ⁻¹ in the Si oxide film formed by the conventional CVD method, but in the Si oxide film according to the above-described embodiment, the Si—OH bond is present. It can be seen that the absorption due to is not present, and the OH group does not exist in the Si oxide film.

FIG. 3 shows the above Si oxide film of 400 cm ⁻¹ to 15 cm.
It is an infrared absorption spectrum up to 00 cm ^-1 . As a comparative example, the infrared absorption spectrum of the thermal oxide film is shown. 1000 cm ^-1
The shape of the absorption spectrum due to the Si—O bond observed at ˜1300 cm ⁻¹ is very similar, and it can be seen that the state of the Si—O bond is as stable and of good quality as the thermal oxide film.

FIG. 4 shows the Si produced by the method described above.
Is a graph showing the SiF ₄ dependence of the dielectric constant of the oxide film. The vertical axis represents the relative permittivity and the horizontal axis represents the SiF ₄ flow rate. It is known that a Si oxide film formed by a conventional CVD method using SiH ₄ and O ₂ has a minimum relative dielectric constant of 3.8 to 3.9. As is apparent from the figure, in this example, a relative dielectric constant of 3.3 to 3.6 was obtained, and it was found that a Si oxide film having a low relative dielectric constant was obtained.

FIG. 5 shows the Si manufactured by the above-mentioned method.
6 is a graph showing the dielectric strength characteristics of an oxide film. The horizontal axis represents breakdown voltage and the vertical axis represents frequency. As is clear from the figure, the breakdown voltage is distributed in the range of approximately 6.5 to 8.0 MV / cm, and it can be said that the dielectric breakdown voltage characteristics are excellent as in the conventional case.

Next, the Si oxide film of the second embodiment formed under the conditions different from those of the above embodiment will be described. The sample S was placed in the reaction chamber 2 of the apparatus (FIG. 1) used in the above-mentioned example, and the Si oxide film was formed on the sample S under the conditions that the microwave power and the O ₂ gas flow rate were optimized. . FIG. 6 is a graph showing the relative dielectric constant with respect to the amount of fluorine in the Si oxide film. The vertical axis represents the relative permittivity and the horizontal axis represents the fluorine content. Fluorine content from 0.01 atomic% to 0.1 atomic
%, The relative permittivity decreases from 3.9 to 3.7, and from 0.1 atomic% to 20 atomic%
It has decreased from 3.7 to 2.9. Fluorine content is 0.1ato
The Si oxide film smaller than mic% cannot be distinguished in characteristics from the conventional Si oxide film.

FIG. 7 is a graph showing the BHF etching rate with respect to the amount of fluorine in the above Si oxide film. The vertical axis represents the BHF etching rate, and the horizontal axis represents the fluorine content. Fluorine content from 0.01 atomic% to 20
As it changes to atomic%, the BHF etching rate becomes
Increased from 3000Å / min to 4800Å / min. The BHF etching rate of a Si oxide film having a fluorine content larger than 20 atomic% exceeds 8000Å / min. The high etching rate indicates that the quality of the film is in a porous state and the reliability as an insulating film is remarkably lowered.
From this, the fluorine content is more than 20 atomic% S
It can be said that it is difficult to apply the i oxide film to the interlayer insulating film and the passivation film.

Next, the third embodiment of the present invention will be concretely described. In the examples described below, an ECR plasma CVD apparatus is used to form a Si oxide film on a sample S. This device is the same as the device shown in FIG. 1 described above except that SiF ₄ and SiH ₄ are selectively introduced from the gas introduction system 7, and corresponding parts have the same reference numerals. The description is omitted. In order to form a Si oxide film on the sample S using this apparatus, first, Ar gas and O ₂ gas are supplied from the gas introduction system 6 into the plasma generation chamber 1 and the gas introduction system 7 is supplied.
To supply SiH ₄ gas into the reaction chamber 2 to generate plasma and form a Si oxide film on the sample S. The Si oxide film is formed to 1000 liters, the microwave oscillation is stopped, and the gas supplied from the gas introduction system 7 is switched from SiH ₄ to SiF ₄ . Then, microwaves are again introduced into the plasma generation chamber 1 to form a Si oxide film containing fluorine.

FIG. 8 shows the Si formed by this embodiment.
It is a schematic cross section of an oxide film. Al wiring 22,2 on substrate 21
The first Si oxide film 23 containing SiH ₄ containing no fluorine is formed on the surface of the sample S on which 2 is formed to a thickness of 1000Å, and the second Si oxide film containing fluorine containing SiF ₄ is formed thereon. 24 is deposited and the surface is almost flat. Since Al, which is a wiring material, reacts with fluorine to form an insulator such as AlF ₃ , it is not preferable to bring SiF ₄ gas into contact with the sample S on which the Al wirings 22 and 22 are formed. By thinly depositing the Si oxide film 23 of SiH ₄ on the Al wirings 22 and 22 as in the present embodiment, the Al wirings 22 and 22 do not react with SiF _4, and
The Si oxide film 24 made of SiF ₄ can be formed.
The Al wirings 22 and 22 may be Al alloy wirings.

Next, a fourth embodiment of the present invention will be specifically described with reference to the drawings. FIG. 9 is a schematic vertical sectional view showing the structure of the ECR plasma CVD apparatus used for carrying out the manufacturing in the fourth embodiment. In the figure, 1 is a plasma generation chamber and 2 is a reaction chamber. In this apparatus, a high-frequency power source 9 is connected to a sample table 5 on which a sample S placed in the reaction chamber 2 is mounted, and a bias voltage is applied to the sample S, except for the above-mentioned drawings. The device is the same as that of the device shown in FIG.

FIG. 10 shows an S manufactured using this apparatus.
SiF with relative permittivity of i oxide film_FourA graph showing the flow rate dependence
Where the vertical axis is the relative permittivity and the horizontal axis is SiF._FourRepresents the flow rate
ing. The gas flow rate under the film forming conditions is 43 sccm for Ar and O.₂But
70sccm, pressure is 2 × 10 ^-3Torr, microwave output
2.8kW, high frequency power 400W, substrate temperature 300 ℃
It As is clear from the figure, the poles with a relative permittivity of 2.9 to 3.0
It can be seen that a low value of Si oxide film is obtained. Also,
FIG. 11 is a graph showing the dielectric strength characteristics of this Si oxide film.
Is. The horizontal axis shows the breakdown voltage and the vertical axis shows the frequency.
It As is clear from the figure, the breakdown voltage is about 6.0.
It is distributed in the range of up to 7.5 MV / cm, which is excellent as before.
It can be said that it has excellent withstand voltage characteristics.

Next, a case will be described in which a Si oxide film is formed as an interlayer insulating film on the sample S on which Al wiring is formed, using the apparatus shown in FIG. First, Ar gas and O ₂ gas are supplied from the gas introduction system 6 into the plasma generation chamber 1, and SiH ₄ gas is supplied from the gas introduction system 7 into the reaction chamber 2 to contain fluorine on the sample S by plasma. Not Si
Form 1000Å oxide film. Then, the oscillation of the microwave is stopped, the SiH ₄ gas is switched to the SiF ₄ gas, and the microwave is again introduced into the plasma generation chamber 1 to form the Si oxide film containing fluorine. At this time, the high frequency power source 9 applies a negative bias voltage to the sample S. This allows
Sputter etching is performed on the sample S simultaneously with film formation.

12 (a) and 12 (b) are schematic cross-sectional views of the Si oxide film formed in this embodiment.
3 is a schematic cross-sectional view of a conventional Si oxide film. 12
As shown in (a), a fluorine-free Si oxide film 43 of SiH ₄ is formed on the surface of a sample S having Al wirings 42, 42 formed on a semiconductor substrate 41 to a thickness of 1000 Å, and is formed thereon. A Si oxide film 44 of SiF ₄ is deposited. Due to the sputter etching, the edge portion 44a of the Si oxide film 44 made of SiF ₄ has a higher sputtering efficiency than the flat portion 44b, and is thus cut and tapered. Also, Si oxide film
When 44 of the deposition progresses, since the flat portion 44c is smaller sputtering efficiency than the flat portion 44b, substantially the deposition rate of the flat portion 44c is increased, as shown in FIG. 12 (b), by SiF ₄ The Si oxide film 44 is deposited with good flatness. Further, since the edge portion 44a is tapered, the Al wirings 42, 42
The Si oxide film 44 also easily enters in between, and defects such as voids do not occur. The Al wirings 22 and 22 may be Al alloy wirings.

FIG. 13 shows a conventional CVD method using SiH _4.
This is a conventional example in which a Si oxide film is deposited on a sample by the method. A Si oxide film 53 of SiH ₄ is deposited on the surfaces of the Al wirings 42, 42 formed on the semiconductor substrate 51. Al
The edge portions 52a, 52a deposited on the wirings 42, 42 come into contact with each other as the film formation progresses, making it difficult for the Si oxide film 53 to enter between the Al wirings 42, 42.
The upper part between the two and 42 is covered with the edge part 52a, and the void 55 is generated. As described above, according to this embodiment, the semiconductor device having the Si oxide film with improved planarization characteristics is manufactured.

Next, a fifth embodiment of the present invention will be specifically described with reference to the drawings. FIG. 14 is a schematic sectional view of a semiconductor device manufactured by the manufacturing method of the fifth embodiment. By using the apparatus shown in FIG. 9 described above, Ar gas and O ₂ gas are supplied from the gas introduction system 6 into the plasma generation chamber 1 and SiF ₄ gas is supplied from the gas introduction system 7 into the reaction chamber 2. By generating a plasma and applying a negative bias voltage to the sample S by the high frequency power source 9, a Si oxide film 64 containing fluorine is formed on the sample S having Al wirings 62, 62 formed on the semiconductor substrate 61. . Then, the Al wiring 6 is formed on the Si oxide film 64.
Form 5,65.

As described above, S using SiF ₄ gas is used.
Since the i-oxide film has a relative dielectric constant of 2.9 to 3.7, Al wiring
Mutual interference noise between the 62, 62 and the Al wirings 65, 65 is reduced, and the signal delay characteristic between the Al wirings 62, 62 and the Al wirings 65, 65 is improved.

The conventional interlayer S having a relative dielectric constant of about 4.0 is used.
Compared with the i oxide film, when the capacitance between the wirings is constant,
The interlayer Si oxide film having a relative permittivity of about 3.0 in this embodiment can be made thinner. For example, when a film thickness of 1 μm is conventionally required, the Si oxide film containing fluorine of the present invention is used.
By forming it with 0.75 μm, it is possible to have the same inter-wiring capacitance. As described above, by using the Si oxide film containing fluorine according to the present invention, it is possible to reduce the film thickness while maintaining the inter-wiring capacitance. Thereby, for example, the aspect ratio of the via hole, which becomes larger with miniaturization, can be reduced.

FIG. 15 is a schematic sectional view of a semiconductor device manufactured by the manufacturing method of the fifth embodiment. Using the apparatus shown in FIG. 9 described above, the gas introduction system 6 is connected to the plasma generation chamber 1
By supplying Ar gas and O ₂ gas into the reaction chamber, supplying SiF ₄ gas into the reaction chamber 2 from the gas introduction system 7 to generate plasma, and applying a negative bias voltage to the sample S by the high frequency power supply 9. A Si oxide film 64 containing fluorine is formed on the sample S having Al wirings 62, 62 formed on the semiconductor substrate 61. Then, the oscillation of the microwave is stopped, the SiF ₄ gas is switched to the SiH ₄ gas, the microwave is again introduced into the plasma generation chamber 1, and 300 Å fluorine-free Si is introduced.
An oxide film 66 is formed. Then, Al wirings 65, 65 are formed on the Si oxide film 66.

As a result, when the Al wirings 65, 65 are formed, contact with the silicon compound gas containing fluorine and the Al wiring 6
The contact of 5,65 with fluorine can be reduced, and the corrosion of the Al wiring 65,65 due to the contact and the change of the crystal grain size can be prevented. Further, by forming the Si oxide film 66 that does not contain fluorine thinly, there is no effect on the wiring, and mutual interference noise and signal delay characteristics are improved compared to the conventional case.

In the above-mentioned manufacturing method, immediately after the formation of the fluorine-containing Si oxide film 64 which is the interlayer insulating film, the high frequency power is increased to increase the sputtering rate on the surface, thereby reducing the fluorine atoms on the surface. Or immediately after the formation of the Si oxide film 64, while applying plasma of a non-reactive gas such as Ar gas, a high frequency bias is applied to the substrate to actively perform sputtering to reduce fluorine atoms on the surface. As a result, the Al wiring 6
It can prevent corrosion of 5,65 and change of crystal grain size.

FIG. 16 is a schematic sectional view of a semiconductor device manufactured by the manufacturing method of the fifth embodiment. Using the device shown in FIG. 9 described above, Al wiring 6 is formed on the semiconductor substrate 61.
On the surface of the sample S on which 2,62 were formed, first, the first S containing no fluorine was formed by the plasma CVD method using SiH _4.
An i-oxide film 63 is formed, and then SiF ₄ gas is supplied from the gas introduction system 7 into the reaction chamber 2 to generate plasma,
By applying a negative bias voltage to the sample S by the high frequency power source 9, the second Si oxide film 64 containing fluorine is provided on the sample S having the Al wirings 62, 62 formed on the semiconductor substrate 61.
To form. Then, the microwave oscillation is stopped and Si
The F ₄ gas is switched to the SiH ₄ gas, and the microwave is again introduced into the plasma generation chamber 1 to form the third Si oxide film 66 containing 300 Å no fluorine. Then, Al wirings 65, 65 are formed on the Si oxide film 66. In the semiconductor device manufactured in this way, the Al wirings 62, 62, and the Al wiring 6
Corrosion of 5,65 fluorine is further prevented.

Next, a sixth embodiment of the present invention will be specifically described with reference to the drawings showing the same. FIG. 17 is a schematic longitudinal sectional view showing the structure of the ECR plasma CVD apparatus used for carrying out the manufacture in the sixth embodiment. In the figure, 1 is a plasma generation chamber and 2 is a reaction chamber. In this apparatus, a DC power source is provided on a sample table 5 on which a sample S placed in the reaction chamber 2 is placed.
10 is connected so that a negative DC electric field is applied to the sample S, O ₂ and N ₂ can be introduced simultaneously or selectively from the gas introduction system 6, and SiF ₄ gas and SiF ₄ gas can be introduced from the gas introduction system 7. The apparatus is the same as the apparatus shown in FIG. 9 described above except that the SiH ₄ gas can be introduced simultaneously or selectively.

FIG. 18 is a schematic sectional view of a semiconductor device manufactured by the manufacturing method of the sixth embodiment. Using the apparatus described above, first, SiF ₄ gas is introduced into the reaction chamber 2 from the gas introduction system 6 to generate plasma on the sample S on which the Al wirings 72, 72 are formed on the substrate 71. Then, a negative bias voltage is applied to the Si oxide film 73 containing fluorine. Then, stop the microwave oscillation and turn the SiF
_{The 4} gas is switched to the SiH ₄ gas, and the microwave is again introduced into the plasma generation chamber 1 to form a 300 Å fluorine-free Si oxide film 74. Then, after forming the uppermost Al wirings 75, 75 on the Si oxide film 74, SiF ₄ gas is again introduced to generate plasma, and a negative bias voltage is applied to the sample S to make Si containing fluorine. An oxide film 76 is formed to fill and flatten the space between the Al wirings 75, 75. After that, the Si nitride film 77 is formed using SiH ₄ gas and N ₂ gas. This Si nitride film 77 functions as a passivation film. When the Si nitride film 77 is formed, S
It instead of iH ₄ gas may be introduced SiF ₄ gas and N ₂ and O ₂ in place of the N ₂ gas, or N ₂ and N
_The Si nitride film 77 may be a Si oxynitride film by introducing ₂ O. By forming the Si oxynitride film, a passivation film having lower stress can be formed.

As described above, the Si oxide film having a low relative dielectric constant is formed between the uppermost Al wirings 75, 75, and the Si nitride film is further formed thereon. In the past, since the surface of the uppermost Al wiring 75,75 was covered with a Si nitride film as a passivation film, a Si nitride film with a high relative dielectric constant (= 6.9) was present between the Al wiring 75,75. However, by coating a Si nitride film having a low relative dielectric constant as in this embodiment, Al
Mutual interference noise between the wires 75, 75 is reduced, and signal delay characteristics are improved. Further, according to the present invention, it is possible to form a Si oxide film having excellent characteristics, and it is possible to reduce the generation of particles.

FIG. 19 is a schematic sectional view of a semiconductor device manufactured by the manufacturing method of the seventh embodiment. By using the apparatus shown in FIG. 9 described above, Ar gas and O ₂ gas are supplied from the gas introduction system 6 into the plasma generation chamber 1 and SiF ₄ gas is supplied from the gas introduction system 7 into the reaction chamber 2. By generating a plasma and applying a negative bias voltage to the sample S by the high frequency power source 9, the Si oxide film 79 containing fluorine is added to the sample S.
To form. In the sample S, Al wirings 78, 78 ... Are formed on the insulating film 81 containing no fluorine. Then, when the surface of the Si oxide film 79 containing fluorine becomes flush with the surface of the Al wirings 78, 78 ...
The F ₄ gas is switched to the SiH ₄ gas, the microwave is again introduced into the plasma generation chamber 1, and the Si oxide film 80 containing no fluorine is formed on the Al wirings 78, 78 ... And the Si oxide film 79 containing fluorine. .

As described above, by embedding the fluorine-containing Si oxide film 79 only between the Al wirings 78, 78, ..., It is possible to suppress an increase in inter-wiring capacitance in the same layer. As a result, the Si oxide film 79 containing fluorine is used only between the wirings involved in the high-speed operation of the semiconductor device, and the conventional Si oxide film containing no fluorine is used for the other parts, at the same cost as the conventional one. A semiconductor device capable of higher speed operation can be formed.

In this embodiment, the insulating film 81 on the lower side of the Al wirings 78, 78 ... And the insulating film 80 not containing fluorine are used for the upper Si oxide film 80. This insulating film may be, for example, a normal Si oxide film formed by plasma CVD using SiH ₄ or TEOS. Further, when the layer in which the Al wirings 78, 78 ... Is formed is the final wiring layer, a passivation film such as silicon nitride is formed on the Al wirings 78, 78 ... And the Si oxide film 79 containing fluorine. To do.

Further, although the Al wiring is used in this embodiment, it is not limited to this, and Al alloy, W, Cu, A is used.
The wiring may be made of a metal such as g, Au, or TiN.

In the above embodiment, SiF is used._FourOver
And O₂However, it is not limited to this.
Instead of fluorine containing silicon compound gas and O₂or
Is N ₂O may be used.

Further, although the ECR plasma CVD method is used as the plasma CVD method in the above-mentioned embodiments, the present invention is not limited to this, and microwave plasma CVD method, RF
A plasma CVD method or the like may be used.

[0057]

As described above, according to the present invention, by forming the Si oxide film by the plasma CVD method using the silicon compound gas containing fluorine, the generation of particles is suppressed and the quality and yield of the semiconductor device are improved. Improve. Further, the present invention has excellent effects such as improving the flattening characteristics of the Si oxide film, increasing the speed of the semiconductor device, and suppressing the increase in inter-wiring capacitance.

[Brief description of drawings]

FIG. 1 is a schematic longitudinal sectional view showing the structure of an ECR plasma CVD apparatus used in a first embodiment of the present invention.

FIG. 2 is an infrared absorption spectrum of the Si oxide film of the first embodiment.

FIG. 3 is an infrared absorption spectrum of the Si oxide film of the first example.

FIG. 4 shows the relative dielectric constant SiF ₄ of the Si oxide film of the first embodiment.
It is a graph showing dependence.

FIG. 5 is a graph showing withstand voltage characteristics of the Si oxide film of the first embodiment.

FIG. 6 is a graph showing the relative dielectric constant with respect to the amount of fluorine in the Si oxide film of the second embodiment.

FIG. 7 is a graph showing the BHF etching rate with respect to the amount of fluorine in the Si oxide film of the second example.

FIG. 8 is a schematic sectional view of a Si oxide film of a third embodiment.

FIG. 9 is a schematic vertical sectional view showing the structure of an ECR plasma CVD apparatus used in a fourth embodiment.

FIG. 10 SiF having a relative dielectric constant of the Si oxide film of the fourth embodiment
₄ is a graph showing the flow rate dependency.

FIG. 11 is a graph showing the dielectric strength characteristics of the Si oxide film of the fourth embodiment.

FIG. 12 is a schematic sectional view of a Si oxide film of a fourth embodiment.

FIG. 13 is a schematic sectional view of a conventional Si oxide film.

FIG. 14 is a schematic cross-sectional view of a semiconductor device manufactured by the manufacturing method according to the fifth embodiment.

FIG. 15 is a schematic cross-sectional view of a semiconductor device manufactured by the manufacturing method according to the fifth embodiment.

FIG. 16 is a schematic cross-sectional view of a semiconductor device manufactured by the manufacturing method according to the fifth embodiment.

FIG. 17: ECR plasma CVD used in the sixth embodiment
It is a typical longitudinal cross-sectional view showing the structure of the device.

FIG. 18 is a schematic cross-sectional view of a semiconductor device manufactured by the manufacturing method according to the sixth embodiment.

FIG. 19 is a schematic sectional view of a semiconductor device manufactured by a manufacturing method according to a seventh embodiment.

[Explanation of symbols]

 1 Plasma generation chamber 2 Reaction chamber 5 Sample stage 6 Gas introduction system 9 High frequency power supply 21,41,51,61,71 Substrate 23,43,63,66,74,80 Fluorine-free Si oxide film 22,42,62 , 65,72,75,78 Aluminum wiring 24,44,53,64,73,76,79 Si oxide film containing fluorine 55 Void

Claims (10)

[Claims] 1. A silicon compound gas containing fluorine and O ₂
Alternatively, a semiconductor device comprising a Si oxide film containing 0.1 to 20 atomic% of fluorine formed by a plasma CVD method using N ₂ O. 2. The semiconductor device according to claim 1, wherein the Si oxide film is formed between adjacent wirings. 3. A silicon compound gas containing fluorine and O ₂
Alternatively, a semiconductor device comprising a Si oxide film having a relative dielectric constant of 3.7 to 2.9 formed by a plasma CVD method using N ₂ O. 4. The semiconductor device according to claim 1, wherein the Si oxide film is an interlayer insulating film. 5. The semiconductor device according to claim 1, wherein the Si oxide film is a passivation film. 6. A silicon compound gas containing fluorine and O ₂
Alternatively, by using N ₂ O and a plasma CVD method, Si
A method of manufacturing a semiconductor device, which comprises forming an oxide film. 7. A step of forming a first Si oxide film by a plasma CVD method using a fluorine-free silicon compound gas and O ₂ or N ₂ O, and a fluorine-containing silicon compound gas and O ₂ or And a step of depositing a second Si oxide film on the first Si oxide film using N ₂ O. 8. A step of forming a second Si oxide film by a plasma CVD method using a silicon compound gas containing fluorine and O ₂ or N ₂ O, and a silicon compound gas containing no fluorine and O ₂ or O _2. And a step of depositing a first Si oxide film on the second Si oxide film by using N ₂ O. 9. A step of forming a first Si oxide film by a plasma CVD method using a fluorine-free silicon compound gas and O ₂ or N ₂ O, and a fluorine-containing silicon compound gas and O ₂ or A step of depositing a second Si oxide film on the first Si oxide film using N ₂ O, and a second silicon oxide gas containing no fluorine and O ₂ or N ₂ O. And a step of forming a third Si oxide film on the Si oxide film. 10. The method for manufacturing a semiconductor device according to claim 6, wherein a plasma CVD method using a silicon compound gas containing fluorine and O ₂ or N ₂ O is performed by applying a negative potential to the substrate. Method.