JP3440714B2 - Method for forming silicon compound based insulating film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicon (Si) containing fluorine (F) as an interlayer insulating film having a low dielectric constant.
The present invention relates to a method for forming a compound type insulating film, and more particularly to a method for forming a SiOF film by a CVD method.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high integration of semiconductor devices, wiring patterns have become finer and multilayered. However, when the step of the interlayer insulating film becomes large and steep due to the miniaturization and high integration of the semiconductor device, the processing accuracy and reliability of the wiring pattern formed on the interlayer insulating film are deteriorated, and the reliability of the semiconductor device itself is deteriorated. It becomes a factor to decrease. For this reason, it is difficult to significantly improve the step coverage (coverage) of the wiring layer mainly made of an Al-based material formed by the sputtering method. At present, it is necessary to form a planarized interlayer insulating film. It is said that.

Conventionally, as a technique for forming a flattened interlayer insulating film, for example, SOG (Spin On Gla) is used.
A method of applying ss), a method of flattening the insulating film with a resist material and then collectively etching back these, a method of reflowing the insulating film by heat treatment, and the like are known. In addition, tetraethoxysilane (hereinafter, TEO
It is called S. Chemical vapor deposition (hereinafter, CV) at atmospheric pressure using a mixed gas of an organic Si compound represented by
It is called D. ), A method of performing plasma CVD using a gas obtained by adding water or oxygen to the above-mentioned organic Si-based compound, and a method of forming an insulating film by utilizing the flow effect at the time of film formation are also drawing attention. .

However, even if the above method is applied,
The degree of flatness is insufficient on wiring patterns with wide wiring intervals,
On the other hand, on a wiring with a narrow wiring interval, "
Since it is difficult to sufficiently bury it, recently, electron cyclotron resonance (hereinafter referred to as ECR) plasma CVD is performed while applying bias power to grow an interlayer insulating film or form a film. A technique for planarizing the interlayer insulating film by chemical mechanical polishing has also been applied.

[0005]

By the way, in order to achieve further miniaturization and higher integration of semiconductor devices,
It is necessary not only to flatten the interlayer insulating film but also to reduce the dielectric constant. This is because as the semiconductor device is miniaturized and highly integrated, the influence of the parasitic capacitance between the wirings on the operation speed of the semiconductor device increases.

As a method of forming a low-dielectric-constant interlayer insulating film, 1993 International Conference on Solid State Devices and Materials Abstracts (Extended Abstract)
ts of the 1993 Internet
nal Conference on SolidSt
ate Devices and material
s, 1993) p161-163,
There is a method of forming an SiOF-based insulating film by plasma CVD using a gas in which C ₂ F ₆ is added to TEOS and O ₂ . In addition, the 40th Japan Society of Applied Physics Association Conference (Spring Annual Meeting 1993) Proceedings 1a-ZV-9, T
A method of forming an SiOF-based insulating film by plasma CVD using a gas in which NF ₃ is added to EOS and O ₂ is disclosed. And in any of the documents, it is shown that the dielectric constant can be lowered by increasing the F concentration in the film.

However, as described above, when the F-based gas is added, the dielectric constant of the insulating film can be lowered, but the film quality deteriorates with an increase in the F concentration, and the hygroscopicity remarkably increases. Will occur.

The 40th Joint Lecture Meeting on Applied Physics (1)
In the 993 Spring Annual Meeting) Proceedings 31a-ZV-9, it is effective to use SiF ₄ gas containing Si and F in the same molecule as the source gas in order to stabilize the film quality. It is shown. However, when a SiOF-based insulating film is formed on a substrate having a step using this method, the burying property is locally deteriorated. For example, in FIG.
, The SiO ₂ film 12 is formed on the Si substrate 121.
When the SiOF insulating film 124 is formed by using SiF ₄ gas on the wafer W on which the wiring patterns 123 having different pattern widths are formed, the narrow recesses adjacent to the wide wiring pattern 123 are formed. Will be insufficiently embedded.

Therefore, the present invention has been proposed in view of such conventional circumstances, and forms a Si compound type insulating film having a low dielectric constant, an excellent film quality, and an excellent filling property. The purpose is to provide a method of doing.

Further, as described above, for the interlayer insulating film of the conventional semiconductor device, CVD or SOG using TEOS is used.
Have been used. However, with the recent higher integration of VLSI, wiring has become finer, and the increase in wiring capacity that limits the processing speed of VLSI has become a problem. Not only does it have good coverage characteristics, but also the interlayer insulating film. It is desired to reduce the dielectric constant of A SiOF film is a material that meets these requirements, but TE by the conventional method is used.
A film formed by a single-frequency RF discharge in which C ₂ F ₆ or the like is added to OS involves moisture absorption due to unstable F and hydrocarbon contained in the film, which adversely affects the wiring reliability of the device.

Therefore, studies have been conducted using (C ₂ H ₅ O) ₃ SiF (TEFS), which is a gas containing Si-F bonds in gas molecules. However, when film formation was performed using TEFS alone, stable film quality was obtained, but the coverage of the side wall of the step was insufficient. So TEFS
Is mixed with TEOS or (C ₂ H ₅ O) ₃ SiF (TES), and the formation of a SiOF film is being studied in a gas system to which oxygen is added. However, although the coverage has been improved so far, the conditions and methods for achieving stable film quality have not been established.

[0012] Therefore, there is a strong demand for a technique of stably introducing F into a film by using a conventional RF discharge CVD apparatus to form a stable film quality. Therefore, the present invention further aims to provide stable film quality conditions and methods.

[0013]

The present invention has been proposed in order to achieve the above-mentioned object, and a plasma chamber for generating plasma and a substrate are placed, and a desired material film is formed on the substrate. Using a plasma CVD apparatus in which a reaction chamber for forming a film is connected, a gas containing a compound capable of releasing an F-based chemical species is introduced into the plasma chamber, and on the substrate,
A Si compound-based insulating film containing F (hereinafter referred to as a SiOF-based insulating film) is formed as the desired material film.

When F is contained in the Si compound type insulating film,
The dielectric constant of this insulating film can be reduced. further,
In the present invention, by releasing the F-based chemical species not in the reaction chamber but in the plasma chamber having a high plasma density,
It is possible to increase the ratio of the ionic species of F to the radical species of. Since the F-based chemical species also act as an etchant for the SiO-based insulating film, the F-based chemical species are likely to accumulate in a narrow recess having a small area to be etched, and the etching is likely to proceed, resulting in insufficient filling. It was However, in the present invention, it becomes possible to efficiently generate the ionic species of F, which is easier to control the incident direction to the substrate, than the radical species of F, which are incident on the substrate in an arbitrary direction. It is possible to suppress the dependency of the embedding characteristics on the step difference of the substrate.

In the present invention, it is preferable to apply a bias power to the substrate, whereby the ionic species of F generated in the plasma chamber as described above are supplied vertically and uniformly to the substrate. Will be done. Further, due to the ion-sputtering action, the denseness of the SiOF insulating film can be improved even for a substrate having a step, and the film quality can be improved. Also,
The embedding characteristics are also improved.

In order to exhibit a sufficient ion sputtering effect, He, Ne, Ar,
It is preferable to introduce an inert gas such as Kr or Xe to ionize them in plasma.

As the compound for releasing the F-based chemical species into the plasma chamber, a fluorocarbon-based compound typified by C ₂ F ₆ or a nitrogen fluoride-based compound typified by NF ₃ may be used. However, it is preferable to use a compound capable of simultaneously releasing Si-based chemical species in the plasma chamber, that is, a Si compound having a Si—F bond. This Si compound may be an inorganic compound or an organic compound. For example, SiF ₄ , SiHF ₃ , SiH ₂ F ₂ , SiH ₃ F, S
i ₂ F ₆ , SiF (OC ₂ H ₅ ) ₃ , SiFH (OC
₂ H ₅ ) ₂ , SiF ₂ (OC ₂ H ₅ ) ₂ , SiF ₃ (OC ₂ H ₅ )
Inorganic or organic silane compounds into which F is introduced can be mentioned. Further, chain-like or cyclic siloxane into which F is introduced may be used. Then, it is preferable to simultaneously introduce O ₂ gas into the plasma chamber.

When introducing a Si compound gas having a Si—F bond and O ₂ gas into the plasma chamber, all the raw materials necessary for forming the SiOF-based insulating film must be prepared in the plasma chamber. Becomes Therefore, it is possible to form the SiOF insulating film without introducing any gas into the reaction chamber. However, for example, if only SiF ₄ gas is used as the Si compound, the Si / F ratio may be too low, and the etching may be dominant rather than the film deposition. Therefore, even when introducing a gas containing a compound capable of releasing Si-based chemical species and F-based chemical species into the plasma chamber, it is preferable to introduce a gas containing a compound capable of releasing Si-based chemical species into the reaction chamber. Is. Here, the gas introduced into the reaction chamber is preferably a Si compound that does not release F-based chemical species, for example, an inorganic silane-based compound represented by SiH ₄ , Si ₂ H ₆ gas or the like. Also,
In addition to alkoxysilane represented by TEOS, chain or cyclic siloxane may be used.

The plasma CVD apparatus used in the present invention may have any plasma generating means as long as the plasma chamber and the reaction chamber are independent. For example, an ECR plasma CVD apparatus or a helicon wave plasma CVD apparatus can be used. When these plasma CVD apparatuses are used, high-density plasma of the order of 10 ¹¹ / cm ³ or more can be generated under a low gas pressure, so that gas dissociation efficiency is high and high-energy ions can be made incident on the substrate. The amount of impurities and the amount of defects in the film can be reduced, and the denseness of the film can be improved. Further, it is possible to form a film having excellent coverage and improve the burying property for a substrate having a step.

When the present invention is applied, a SiOF insulating film having a low dielectric constant and excellent film quality can be formed. Therefore, this film is suitable for application as an interlayer insulating film of a semiconductor device. Since the interlayer insulating film formed by applying the present invention also has excellent filling characteristics,
Insulation between wires can be reliably performed.

Further, according to the present invention, for example, a parallel plate type plasma CVD apparatus is used, and S is used as a source gas in the reaction chamber.
Gas of organic Si compound containing i-F bond and other organic Si
A silicon compound type insulating film characterized by forming a fluorine-containing silicon compound type insulating film on a substrate by introducing a mixed gas of compound gases and further introducing oxygen or a gas containing oxygen as an additive gas. A film forming method for the same is provided.

In the present invention using the parallel plate type plasma CVD apparatus, the mixing ratio of the organic Si compounds in the mixed gas is α: β: γ ... The number of carbon atoms contained in one molecule of the gas is a, b, c ... In turn, the number of hydrogen atoms is k, l,
m, and when the gas decomposition rate of each organic Si compound is δ%, the oxygen addition ratio is at least [{α (a + k
/2)+β(b+l/2)+γ(c+m/2)...}/
It is desirable to add them in a molar ratio of about δ] × 100.

A stable silicon compound insulating film can be formed by such a film forming method.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments to which the method for forming a Si compound type insulating film according to the present invention is applied will be described below with reference to the drawings.

First Embodiment In this embodiment, a method for forming a SiOF insulating film using an ECR plasma CVD apparatus will be described.

Here, the ECR plasma CV used for film formation
As shown in FIG. 1, the D apparatus includes a plasma chamber 1 in which plasma is generated and a reaction chamber 3 in which a wafer W is placed and a desired film is formed.

Here, in the plasma chamber 1, the microwave generated by the magnetron passes through the inside of the waveguide 4 and is guided through the quartz window 5. A solenoid coil 6 is arranged around the plasma chamber 1 so that a magnetic field orthogonal to the electric field generated by the microwave can be generated.

Further, a ring-shaped first gas supply pipe 7 is opened in the plasma chamber 1. And this first
Although not shown, the gas supply pipe 7 of He, Ne, Ar,
It is connected to a supply source of an inert gas such as Kr and Xe and a supply source of O ₂ gas, and is also connected to a supply source of a compound gas capable of releasing an F-based chemical species.

On the other hand, the reaction chamber 3 is provided with an exhaust port 10 for reducing the pressure inside the reaction chamber 3, and a loading path 11 for loading the wafer W into the reaction chamber 3 is a gate valve. It is connected via 12. A susceptor 8 on which the wafer W is placed is arranged in the reaction chamber 3. A heater 13 is built in the susceptor 8 so as to heat the wafer W, and a matching network (M / M) for impedance matching is provided.
The RF power source 14 for bias application is connected via N) 15 so that bias power can be applied to the wafer W.

A ring-shaped gas supply pipe 9 for supplying a compound gas capable of releasing Si chemical species is opened in the reaction chamber 3.

Therefore, E having the above structure
To form a SiOF-based insulating film using a CR plasma CVD apparatus, an inert gas, an O ₂ gas, and a compound gas capable of releasing an F-based chemical species are introduced into the plasma chamber 1, and ECR is performed. Is used to generate ECR plasma PE having a high ion current density under a low gas pressure. At this time, when the compound gas capable of releasing the F-based chemical species is supplied, the F ion species are efficiently generated in the ECR plasma PE.

Then, in the reaction chamber 3, a compound gas capable of releasing Si-based chemical species is supplied to the ECR plasma PE, whereby desired chemical species are generated and deposited on the wafer W. At this time, by controlling the substrate bias independently of plasma generation, the ion species of F can be supplied vertically and uniformly to the wafer W, and while improving the denseness of the deposited film, Deposition can be performed with excellent embedding characteristics.

In the plasma chamber 1, Si having a Si--F bond is used as a compound gas capable of releasing F type chemical species.
When a compound gas is introduced, SiO ₂ is introduced into the plasma chamber 1.
Although deposition of a system insulating film may occur, there is no possibility that particles will be generated here because F-based chemical species exist in the same plasma chamber 1 and this acts as an etchant.

Second Embodiment In this embodiment, a method of forming an SiOF insulating film using a helicon wave plasma CVD apparatus will be described.

Here, the helicon wave plasma CVD apparatus used for film formation, as shown in FIG. 2, diffuses the helicon wave plasma generation unit and the helicon wave plasma generated here, and generates in this plasma. And a film forming unit for depositing the chemical species thus deposited on the wafer W.

The helicon wave plasma generating section is a bell jar 31 (corresponding to a plasma chamber) made of a non-conductive material for generating the helicon wave plasma PH, and supplies a predetermined gas into the bell jar 31. 1 gas supply pipe 48, having two loops that go around the bell jar 31,
A loop antenna 32 for coupling F power to plasma and a solenoid coil 33 which is provided so as to circulate around the bell jar 31 and generates a magnetic field along the axial direction of the bell jar 31 are the main constituent elements. A lid 30 made of a non-conductive material is provided above the bell jar 31, and a first gas supply pipe 48 penetrates the lid 30.

The first gas supply pipe 48 is not shown,
It is connected to an inert gas supply source such as He, Ne, Ar, Kr, and Xe for plasma generation and an O ₂ gas supply source, respectively, and also serves as a compound gas supply source capable of releasing F-based chemical species. Is also connected. RF power is applied to the loop antenna 32 from a plasma excitation power source 34 via a first matching network (M / N) 35 for impedance matching, and the upper and lower two loops thereof have mutually opposite rotations. Directional current flows.

The solenoid coil 33 is an inner circumferential solenoid coil 33a which mainly contributes to the propagation of the helicon wave.
And the outer peripheral side solenoid coil 33b which mainly contributes to the transportation of the helicon wave plasma PH has a double structure.

On the other hand, the film forming section is a diffusion chamber 37 (corresponding to a reaction chamber) connected to the bell jar 31 described above.
A ring-shaped second gas supply pipe 38 for supplying a predetermined gas into the diffusion chamber 37 and a wafer stage 39 for mounting the wafer W in the diffusion chamber 37 are the main constituent elements.

The diffusion chamber 37 is made of a conductive material such as stainless steel, and especially the wafer stage 3
The portion of the top plate 41, which is the facing surface of 9, serves as a large-area DC ground electrode for the substrate bias. Further, the diffusion chamber 37 is provided with an exhaust port 40 for decompressing the inside thereof, and a loading path 46 for loading the wafer W into the diffusion chamber 37 is connected via a gate valve 47. ing.

The second gas supply pipe 38 is not shown,
It is connected to a supply source of compound gas capable of releasing Si-based chemical species.

The wafer stage 39 is the diffusion chamber 3
It consists of a conductive member that is electrically insulated from the wall surface of 7.
It is connected to a bias applying RF power source 42 via a second matching network (M / N) 43. Further, inside the wafer stage 39, a heater 44 for keeping the wafer W during film formation at a desired temperature is built in.

Further, outside the diffusion chamber 37 described above, a permanent magnet 45 capable of generating a multicusp magnetic field is arranged as an auxiliary magnetic field generating means in order to converge the divergent magnetic field in the vicinity of the wafer stage 39. In addition,
The arrangement position of the permanent magnet 45 is not limited to the illustrated example, and a solenoid coil for forming a mirror magnetic field may be arranged instead of the permanent magnet 45.

In order to form a SiOF type insulating film by using the helicon wave plasma CVD apparatus having the above-mentioned structure, an inert gas, an O ₂ gas and an F type chemical species are placed in the bell jar 31. A helicon wave plasma PH is generated in the bell jar 31 by introducing a releasable compound gas. At this time, when the compound gas capable of releasing the F-based chemical species is supplied, the F ion species are efficiently generated in the helicon wave plasma PH.

Then, the helicon wave plasma PH is drawn into the diffusion chamber 37, and a compound gas capable of releasing Si-based chemical species is supplied toward the helicon wave plasma PH to generate a desired chemical species. ,
A film is formed by depositing this on the wafer W.
At this time, by controlling the substrate bias independently of plasma generation, the ion species of F can be supplied vertically and uniformly to the wafer W, and while improving the denseness of the deposited film, Deposition can be performed with excellent embedding characteristics.

The helicon wave plasma CVD apparatus is also
Similar to the first embodiment, even if the Si-based chemical species are supplied into the bell jar 31, the presence of the F-based chemical species prevents the generation of particles.

Third Embodiment In this embodiment, a method of forming an SiOF insulating film using a parallel plate plasma CVD apparatus will be described.

FIG. 6 is a block diagram of a parallel plate type plasma CVD apparatus used for film formation in this embodiment. An upper electrode 202 connected to an RF power source (not shown) and a lower electrode 203 connected to ground are provided in the reaction chamber 201, and these form a pair of parallel plate electrodes. A wafer 205 to be deposited is mounted and supported on the lower electrode 203. A heater 204 is provided below the lower electrode 203.
And heats the wafer 205 through the lower electrode 203 to raise the temperature. The heating of the wafer is carried out at a predetermined temperature suitable for the film forming reaction, but it is desirable to carry out the heating as low as possible unless the film quality is deteriorated. The reaction chamber 201 is connected to a vacuum exhaust device (not shown), the inside of the reaction chamber 201 is vacuum exhausted during a film formation reaction, and a source gas described later is introduced.

The upper electrode 202 is internally formed as a gas chamber, to which the gas introduction port 212 is connected, and has a number of injection ports on the lower surface, and the gas is uniformly dispersed from the injection ports into the reaction chamber 201. It is configured as a shower electrode for spraying.

The oxygen gas supply source 2 is connected to the gas inlet 212.
10 and first and second source gas sources 208a, 208b
Are respectively connected via valves. The first and second source gas sources 208a and 208b have the same configuration (only one is shown in the figure), and while heating a liquid organic silicon compound 206 described later with a heater 207, helium (He) is used as a bubbling gas. And a bubbler 209 that evaporates the organosilicon compound 206.

Parallel plate type plasma C having the above structure
To form a SiOF-based insulating film using a VD device,
A gas of an organic Si compound containing a Si—F bond is introduced as a source gas into the reaction chamber 201 from a first source gas source 208a, and another organic Si compound (for example, an organic Si compound containing a Si—O bond) is introduced. Gas as the second source gas source 208b
From above, and further oxygen or a gas containing oxygen is introduced, an RF voltage is applied, and the upper and lower electrodes 202,
Plasma is generated between 203. As a result, the wafer 2
05, a stable film quality of the SiOF insulating film can be obtained.

The conditions and method for obtaining a stable film quality as described above are as follows: the mixing ratio of the gas of the organic Si compound containing the Si--F bond and the gas of the other organic Si compound is α:
In the case of β: γ ..., the number of carbon atoms contained in one molecule of the gas of each organic Si compound is a, b, c ...
When the number of hydrogen atoms is k, l, m ... And the gas decomposition rate of each organic Si compound is δ%, the oxygen addition ratio is at least [{α (a + k / 2) + β (b + l / 2) +
It is to be added at a molar ratio of about γ (c + m / 2) ...} / δ] × 100.

The above-mentioned conditions and methods have been devised based on the following scientific knowledge. That is, it is known that when oxygen is added to the organic Si compound, carbon and hydrogen in the organic Si compound are removed in the form of CO, CO ₂ , H ₂ O during the film formation reaction, and therefore, it is known that The film requires oxygen in an amount corresponding to the hydrocarbon in the organic Si compound. Therefore, as an example, (C ₂ H ₅ O) ₃ Si
A case where F and (C ₂ H ₅ O) ₃ SiH are mixed as a source gas at a molar ratio of 1: 1 and used will be described. In this case, there are 6 carbon atoms and 15 hydrogen atoms in one molecule of the source gas (C ₂ H ₅ O) ₃ SiF, and the source gas (C ₂ H ₅ 0) ₃ SiH 6 carbon atoms in one molecule
There are 16 hydrogen atoms. Therefore, 12 carbon atoms and 31 hydrogen atoms are present in total of both source gases. It can be understood that about 28 O ₂ molecules are required if it is considered that they are simply removed in the form of CO ₂ and H ₂ O. However, not all of the introduced O ₂ actually contributes to the reaction, and those activated in plasma are mainly used for the reaction. Therefore, if the decomposition rate of the mixed gas in the plasma is δ and the decomposed O ₂ is activated, the oxygen gas required to remove hydrocarbons can be simply estimated (28 / δ). × 100. Further, assuming that the raw material gas to be decomposed is about 30% of the whole, the active O _{2 which} is considered to contribute to the reaction is (C ₂ H ₅ O) ₃ Si when the addition ratio is shown by a molar ratio.
F: (C ₂ H ₅ O) ₃ SiH: O ₂ = 1: 1: 94 is required, and in fact, all of the oxygen that became active species in plasma is used for removing organic residues. Therefore, it is necessary to mix oxygen in the above proportion or more depending on the conditions. By adding oxygen on the basis of such knowledge, hydrocarbons in the film are desorbed by the above-described action, and the stability of the film quality can be improved.

[0054]

EXAMPLES In the following, in a semiconductor device manufacturing process, a plasma CV as shown in the first and second embodiments is applied to a substrate (wafer) having a step.
An example of forming a SiOF-based insulating film using the D device will be described.

Example 1 In this example, a SiOF insulating film was formed by using the ECR plasma CVD apparatus shown in the first embodiment.

Specifically, as shown in FIG. 3, a wafer W is prepared in which a SiO ₂ film 22 and a wiring pattern 23 made of an Al-based material are formed in this order on a Si substrate 21 on which transistor elements are formed. Then, this wafer W was placed on the susceptor 8 of the ECR plasma CVD apparatus shown in FIG. Then, the temperature of the wafer W was raised by the heater 13 and bias power was applied by the bias applying RF power source 14.

In the plasma chamber 1, Ar gas, O ₂
SiF ₄ was introduced as a gas and further as a compound gas capable of releasing F-based chemical species, and the ECR plasma PE generated here was diffused into the reaction chamber 3. Then, toward the ECR plasma PE, SiH ₄ gas was supplied as a compound gas capable of releasing Si-based chemical species.

The film forming conditions are as follows: Gas introduced into plasma chamber: SiF ₄ flow rate 20 sccm O ₂ flow rate 140 sccm Ar flow rate 70 sccm Gas introduced into reaction chamber: SiH ₄ flow rate 10 sccm Pressure: 0.2 Pa Microwave power: 2000 W ( 2.45 GHz) RF bias power: 2000 W (13.56 MHz) Wafer temperature: 200 ° C.

As a result, as shown in FIG. 4, the interlayer insulating film 24 made of the SiOF film was formed on the wafer W with excellent filling characteristics.

After that, an annealing treatment was performed. The annealing conditions were as follows: Annealing gas: Diluted source gas with N ₂ gas containing 3% H ₂ Flow rate: 8000 sccm Annealing time: 60 minutes Pressure: Atmospheric pressure Annealing temperature: 400 ° C.

Then, a corrosion test was conducted on the wafer on which the above-mentioned interlayer insulating film 24 was formed. The conditions of this corrosion test were as follows: Corrosion test conditions Hydrochloric acid concentration: 5% Test time: 5 minutes Solution temperature: 25 ° C.

As a result of this corrosion test, no corrosion was observed on the Al-based wiring 23. From this, it was found that the interlayer insulating film 24 formed as described above exhibits good water resistance and corrosion resistance.

The quality of the interlayer insulating film 24 was improved because the high-density ECR plasma PE was used, so that the gas dissociation efficiency was excellent, and high-energy ions were transferred to the wafer W by applying bias power. It is possible to reduce the amount of impurities and the amount of defects in the film and improve the denseness of the film. Also,
The embedding property was improved because the compound gas capable of releasing the F-based chemical species was introduced into the plasma chamber 1 rather than into the reaction chamber 3, so that the ionic species of F were efficiently generated, and this is due to the bias power. By the application, the film was supplied vertically and uniformly to the wafer W, so that the film was not thinned in the step concave portion of the wafer W, and the step dependency of the coverage was suppressed.

In this embodiment, the plasma chamber 1 is
As the compound gas capable of releasing the F-based chemical species, a compound gas such as SiF ₄ which also releases the Si-based chemical species was introduced. However, the F-based chemical species exist in the plasma chamber 1, and this acts as an etchant. Therefore, S in the plasma chamber 1
The iO-based insulating film was not deposited and became particles.

Example 2 In this example, a SiOF-based insulating film was formed by using the helicon wave plasma CVD apparatus shown in the second embodiment.

Specifically, a wafer as shown in FIG. 3 was prepared, and this wafer W was placed on the wafer stage 39 of the helicon wave plasma CVD apparatus shown in FIG.
Then, the temperature of the wafer W was raised by the heater 44 and bias power was applied by the RF power source 42.

In the bell jar 31, Ar gas, O ₂
Si ₂ F ₆ was introduced as a gas and further as a compound gas capable of releasing F-based chemical species, and the helicon wave plasma PH generated here was diffused in the diffusion chamber 37. And
To the helicon wave plasma PH, SiH ₄ gas is supplied as a compound gas capable of releasing Si,
An F film was formed.

The film forming conditions were as follows: Gas introduced into bell jar: Si ₂ F ₆ flow rate 10 sccm O ₂ flow rate 140 sccm Ar flow rate 70 sccm Gas introduced into diffusion chamber: SiH ₄ flow rate 70 sccm Pressure: 0.2 Pa RF power for plasma excitation : 1800 W (13.56 MHz) RF power for bias application: 2000 W (13.56 MHz) Wafer temperature: 400 ° C.

As a result, as shown in FIG. 4, the interlayer insulating film 24 made of the SiOF film was formed on the wafer W with excellent filling characteristics.

After this, an annealing treatment was performed in the same manner as in Example 1, and then a corrosion test was conducted. As a result of this corrosion test, no corrosion was observed on the Al-based wiring 23. From this, it was found that the interlayer insulating film 24 formed as described above exhibits good water resistance and corrosion resistance.

The film quality of the interlayer insulating film 24 was improved because the gas dissociation efficiency was excellent and the high-energy ions were allowed to be incident on the wafer W, as in Example 1. This is because the amount of impurities and the amount of defects therein can be reduced and the denseness of the film can be improved.
Further, the reason why the burying characteristic is improved is that the ion species of F are efficiently generated and are supplied to the wafer W vertically and uniformly, so that the step dependency of the coverage is suppressed.

Also in this embodiment, in the plasma chamber 1,
As the compound gas capable of releasing the F-based chemical species, a compound gas that also releases the Si-based chemical species was introduced.
Since the F-based chemical species in the inside function as an etchant, the SiO-based insulating film was not deposited as particles in the plasma chamber 1.

Further, in this embodiment, the plasma chamber 1
Since a compound gas having a Si—Si bond such as Si ₂ F ₆ was supplied to the substrate, the film formation rate could be increased. This is Si-S when comparing the binding energy between two atoms.
The bond energy of the i-bond is smaller than that of the Si-H bond, and the Si-Si bond is preferentially broken in plasma. Therefore, when a disilane-based compound is used, the monosilane-based compound can be used even under the same discharge dissociation conditions. This is because the amount of Si active species supplied per molecule is doubled by simple calculation as compared with the case where a compound is used.

Example 3 In this example, an ECR plasma CVD apparatus is used as in Example 1, and an organic Si compound is used as a compound gas capable of releasing F-type chemical species supplied to the plasma chamber 1.

In this embodiment, Ar gas, O ₂ gas, and SiF (OC ₂ H ₅ ) ₃ as a compound gas capable of releasing F-based chemical species are introduced into the plasma chamber 1 and generated there. The ECR plasma PE was diffused into the reaction chamber 3.
Then, toward the ECR plasma PE, a Si (OC ₂ H ₅ ) ₄ gas was supplied as a compound gas capable of releasing Si to form a SiOF film.

The film forming conditions are as follows: Gas introduced into plasma chamber: SiF (OC ₂ H ₅ ) ₃ carrier He included, flow rate 100 sccm O ₂ flow rate 200 sccm Ar flow rate 70 sccm Gas introduced into reaction chamber: Si (OC ₂ H ₅ ) ₄ Flow rate 100 sccm Pressure: 0.3 Pa Plasma excitation RF power: 1800 W (2.45 GHz) Bias application RF power: 2000 W (13.56 MHz) Wafer temperature: 400 ° C.

As a result, as shown in FIG. 4, the interlayer insulating film 24 made of the SiOF film was formed on the wafer W with excellent filling characteristics.

After that, an annealing treatment was performed in the same manner as in Example 1, and then a corrosion test was conducted. As a result of this corrosion test, no corrosion was observed on the Al-based wiring 23. From this, it was found that the interlayer insulating film 24 formed as described above exhibits good water resistance and corrosion resistance.

The film quality of the interlayer insulating film 24 is improved.
The reason why the embedding property is good is that
This is similar to the second embodiment. In addition, in this embodiment,
In the plasma chamber 1, SiF (OC₂H_Five)₃Such as organic Si
Compound was supplied, but F generated in the plasma chamber 1
Due to the cleaning effect of the chemical species,
Pollution and particles due to SiO-based insulation film
I never messed up. Example 4 In this example, the parallelism shown in the third embodiment described above is used.
SiOF system using a flat-plate plasma CVD device (Fig. 6)
An insulating film was formed.

Specifically, as shown in FIG. 7A, an interlayer insulating film 232 made of SiO ₂ or the like is formed on a semiconductor substrate 231 made of Si or the like, and an Al wiring layer 233 is formed thereon. The prepared wafer 205 is prepared, and this wafer 2
05 was placed on the lower electrode 203 of the CVD apparatus shown in FIG. Then, the wafer 204 is heated by the heater 204.
5 was heated and heated, and high frequency power was applied by an RF power source of 13.56 MHz to generate plasma.

In the reaction chamber 201, (C ₂ H ₅ O) ₃ SiF as a gas of an organic Si compound containing a Si--F bond is used.
Was introduced from the bubbler 209 of the first raw material gas source 208a, introduced as a gas of an organic Si compound containing an Si-O bond the _{(C 2 H 5 O) 3} SiH from the bubbler of the second raw material gas source 208b, Further, O ₂ gas was added. Here, it is an organic Si compound containing a Si—F bond (C ₂ H ₅
O) ₃ SiF (triethoxyfluorofuran) and Si-
(C ₂ H ₅ O) ₃ Si, which is an organic Si compound containing an O bond
Since H (triethoxysilane) is a liquid material, it is heated to 48 ° C. by the heater 207, bubbled with He, and introduced into the reaction chamber. The addition ratio of oxygen is (C ₂ H ₅ O) ₃ SiF in molar ratio in consideration of the gas decomposition rate (20%):
(C ₂ H ₅ O) ₃ SiH: O ₂ = 1: 2: 300.

The film forming conditions in this example are as follows: (C ₂ H ₅ O) ₃ SiF / He bubbling gas flow rate: 50
0 sccm (C ₂ H ₅ O) ₃ SiH / He bubbling gas flow rate: 10
00 sccm O ₂ gas flow rate: 8000 sccm Pressure: 650 Pa RF power: 750 W Wafer temperature: 400 ° C. Electrode distance: 10 mm

Under these conditions, as shown in FIG. 7B, the interlayer insulating film 234 is covered with the aluminum wiring layer 233.
Was formed. As a result of investigating the change with time of the relative dielectric constant of the insulating film 234 obtained here, the relative dielectric constant was 3.8, which did not change for one month. It was also confirmed that the film structure for absorbing infrared rays did not change for a month as well.

Example 5 In this example, as in Example 4, the parallel plate plasma CVD apparatus shown in the third embodiment was used to form SiO 2.
An F type insulating film was formed.

Specifically, in the fourth embodiment, Si--F is used.
(C ₂ H ₅ O) ₃ SiF which is an organic Si compound containing a bond
And an organic Si compound containing a Si—O bond (C ₂ H ₅
Since (O) ₃ SiH is a liquid material, the temperature was raised, and bubbling with He was introduced into the reaction chamber. In this example, liquid (C ₂ H ₅ O) ₃ SiF and (C ₂ H ₅ O) were introduced. a film was formed by introducing into the reaction chamber directly injection scheme ₄ Si.
Here, the addition ratio of oxygen is a molar ratio of (C ₂ H ₅ O) ₃ SiF: (C ₂ H ₅ O) ₄ S in consideration of the gas decomposition rate (20%).
i: O ₂ = 1: 2: 360.

The film forming conditions in this example are: (C ₂ H ₅ O) ₃ SiF: 50 sccm (C ₂ H ₅ O) ₄ Si: 100 sccm O ₂ gas flow rate: 8000 sccm Pressure: 650 Pa RF power: 750 W Wafer temperature : 400 ° C. Distance between electrodes: 10 mm.

With respect to the film obtained under the above conditions, the change with time of the relative dielectric constant was investigated, and as a result, the relative dielectric constant was 3.
At 8 it remained unchanged for a month. It was also confirmed that the film structure for absorbing infrared rays did not change for a month as well.

Although the method for forming the Si compound type insulating film according to the present invention has been described above, the present invention is not limited to the above-mentioned embodiments. For example, Examples 1 to 3
In the above, Ar gas was added as an inert gas,
He, Ne, Kr, Xe or the like may be used instead of Ar gas.

Further, in Examples 1 and 2, SiF was used as the compound gas capable of releasing the F-based chemical species.
₄ and Si ₂ F ₆ were used, but instead of these, SiH
F ₃ , SiH ₂ F ₂ , SiH ₃ F or the like may be used. Furthermore, in Examples 1 and 2, SiH ₄ was supplied to the reaction chamber 3 or the diffusion chamber 37, but other inorganic silane compounds such as Si ₂ H ₆ may be supplied instead of SiH _4. .

In the third embodiment, SiF is used as the compound gas capable of releasing the F-based chemical species introduced into the plasma chamber 1.
Although (OC ₂ H ₅ ) ₃ is used, other F-containing alkoxysilane, alkylsilane, siloxane or the like may be used instead. In addition, as of C2F ₆ and NF _3,
A compound that does not release Si-based chemical species may be used. On the other hand, although Si (OC ₂ H ₅ ) ₄ was used as the compound gas capable of releasing the Si-based chemical species introduced into the reaction chamber 3, other organic silane compounds may be used, or inorganic silane compounds may be used. I don't mind. Further, chain-like or cyclic siloxane or the like may be used.

Further, the plasma CVD apparatus as shown in the first and second embodiments may be used alone, but is used as one chamber of a multi-chamber apparatus and other It may be connected to the above device via a vacuum transfer path.

In addition, the structure of a wafer on which a film is formed by applying the present invention, various conditions at the time of film formation, and the like can be appropriately changed.

[0093]

As is apparent from the above description, when the present invention is applied, it is possible to form a Si compound type insulating film having a low dielectric constant and excellent film quality with excellent embedding characteristics. Becomes

Therefore, if it is applied to the formation of the interlayer insulating film, the parasitic capacitance between the miniaturized / multilayered wiring patterns can be reduced and the reliability becomes high.

Therefore, by applying the present invention to the manufacturing process of a semiconductor device, it is possible to provide a high speed product with high reliability.

Further, it is possible to improve the coverage characteristic and to form an insulating film of stable film quality with little change with time in relation to semiconductor device characteristics such as relative permittivity.
A highly reliable semiconductor product can be obtained over a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of an ECR plasma CVD apparatus used in the present invention.

FIG. 2 Helicon wave plasma CV used in the present invention
The schematic diagram which shows the structural example of D apparatus.

FIG. 3 is a schematic cross-sectional view showing a wafer on which a wiring pattern is formed.

FIG. 4 is a schematic cross-sectional view showing a state in which an interlayer insulating film is formed on the wafer of FIG.

FIG. 5 is a schematic cross-sectional view showing a wafer on which a SiOF insulating film is formed by a conventional method.

FIG. 6 is a configuration diagram of a parallel plate type CVD apparatus to which the present invention is applied.

FIG. 7 is an explanatory diagram of a wafer cross-sectional configuration when a film is formed by the apparatus of FIG.

[Explanation of symbols]

1: plasma chamber, 3: reaction chamber, 7: first gas supply pipe,
9: second gas supply pipe, 14: RF power supply for bias application, 21: Si substrate, 22: SiO ₂ film, 23: wiring pattern, 24: interlayer insulating film, 201: reaction chamber, 202:
Upper electrode, 203: Lower electrode, 205: Wafer, 208
a: first source gas source, 208b: second source gas source, 21
0: oxygen gas supply source, 212: gas inlet.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-333919 (JP, A) JP-A-4-360533 (JP, A) JP-A-7-74245 (JP, A) JP-A-9- 167767 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/31 C23C 16/30 C23C 16/50 H01L 21/316

Claims (4)

(57) [Claims] 1. A plasma CVD apparatus comprising a plasma chamber for generating plasma, a substrate on which a substrate is placed, and a reaction chamber for forming a desired material film on the substrate, is connected to the plasma chamber. A gas containing a compound capable of releasing a fluorine-based species is introduced, and a silicon-based species is introduced into the reaction chamber.
Of a silicon compound insulating film containing fluorine as the desired material film is formed on the substrate by introducing a gas containing a compound capable of releasing hydrogen Method. 2. The method for forming a silicon compound type insulating film according to claim 1, wherein a bias power is applied to the base. 3. The method for forming a silicon compound insulating film according to claim 1, wherein a silicon compound having a Si—F bond is used as the compound capable of releasing the fluorine-based chemical species. 4. An electron cyclotron resonance plasma CVD device or a helicon wave plasma CVD device is used as the plasma CVD device.
7. A method for forming a silicon compound-based insulating film according to.