JPH07273216A - Forming method of metal oxide film - Google Patents

Abstract

PURPOSE:To prevent a metal oxide film from deteriorating in permittivity by a method wherein the metal oxide film is formed through such a manner that a metal compound which contains carbon and at least one of halogen, organic compound possessed of hydroxyl groups, and oxygen raw gas possessed of oxygen radicals are introduced into a discharge chamber and turned into plasma gas, and the plasma gas is introduced into a film forming chamber and formed into the metal oxide film through a CVD method. CONSTITUTION:A strontium titanate film 48 is formed through a CVD method, material gas is bubbled with Ar gas, ethanol is supplied into a reaction tank through another system, oxygen is turned into plasma as oxidizing agent in a stage precedent to a reaction tank, and oxygen free radicals are supplied together with produced promoter used for a halogen elimination reaction. Thereafter, a nickel film 49 is formed on all the surface of a substrate through a CVD method and patterned into a capacitor upper electrode by a conventional lithography technique and sputtering for fully forming a memory cell basic structure. Thus, a metal oxide film capable of serving as a capacitor insulating film without disturbing a perovskite crystal structure can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal oxide film, and more particularly to a method for forming a metal oxide film as an insulating film used in a semiconductor device.

[0002]

2. Description of the Related Art One of semiconductor devices is a DRAM (Dynamic Random) as a semiconductor memory device that combines a capacitor and a transistor to store information.
omAccess read write Memor
y).

In this type of semiconductor memory device, conventionally,
A silicon oxide film was used as the capacitor insulating film formed between the upper electrode and the lower electrode of the capacitor,
Along with the rapid integration of devices, materials having a larger dielectric constant than silicon oxide film have been studied to compensate for the decrease in capacitor capacitance due to miniaturization, such as using a laminated film of a silicon nitride film and a silicon oxide film. Improvements are being attempted.

In order to realize a capacitor having a higher capacity, a material having a larger dielectric constant than silicon nitride film or silicon oxide film is being studied. It is necessary to use a material having a large dielectric constant as much as possible in order to cope with an increase in capacitance of the capacitor due to further miniaturization in the future.

From these requirements, a high dielectric constant having a perovskite type crystal structure such as strontium titanate, barium titanate, and PZT whose permittivity is 20 to 1000 times higher than that of a silicon oxide film. The use of body materials for the capacitor insulating film is being studied.

It is known that a metal oxide film having a perovskite type crystal structure causes a large atomic polarization, thereby exhibiting a high dielectric constant. This is because the central atom of the crystal lattice can change greatly. Therefore, in order to develop a high dielectric constant, it is essential to form a perovskite type crystal structure without disorder.

On the other hand, in order to apply such a high-dielectric-constant metal oxide film to a capacitor insulating film of a DRAM, a film forming method having a good covering property is required even for a three-dimensional structure such as a trench capacitor. LPCVD meets these requirements
The law is suitable.

In general, organometallic compounds are often used as raw materials for these high dielectric constant metal oxide films. Since the organometallic compound as a raw material is usually used by bonding an alkoxide group or the like, a large amount of C or H is contained in one metal atom, and the incorporation of C into the film becomes a problem. . On the other hand, since metal atoms such as Sr, Ba, and Cu are difficult to vaporize with an alkoxide compound, an organic substance having a large molecular weight, for example, an acetylacetone-based organic substance is coordinated to facilitate vaporization as a metal complex. There is no change in the point that mixing into is a problem.

Further, even when such a metal complex coordinated with a large organic molecule is used, at present, there is no organometal having a high vapor pressure suitable for the CVD method at room temperature.

Further, in order to vaporize the metal raw material of Group IIa such as Sr and Ba, it is required to keep the metal raw material at a high temperature of 150 ° C. or higher.
It is necessary to heat a main part such as a valve at least at 150 ° C. or more and to flow an extremely large amount of bubbling gas, which increases the load on the device.

On the other hand, even in the case of the group IIa metal raw material described above, by including halogen such as F in the organic molecule of the ligand, an organometallic compound having a relatively high vapor pressure and easily vaporized can be obtained. Further, the vapor pressure of a Group IIa metal halide such as SrI _{2 is} also higher than that of a Group IIa organometallic compound containing no halogen, and it is also thermally stable.

However, Group IIa metal forms a metal oxide because a halide can thermodynamically exist more stably than a metal oxide when performing CVD with oxygen as an oxidant in a relatively low temperature region. Without doing so, a substance containing a metal halide, a carbonate, etc. is formed.

In contrast to CVD using only oxygen as an oxidant, C using H ₂ O and O ₂ as oxidants is used.
Halogen can be removed by VD, and an actual example of film formation has been reported (LAWills and BWWessels, Mat.Re.
s.Soc.Symp.Proc.Vol.243. p217 1992).

However, the above CVD method requires a high film forming temperature of 800 ° C. or higher. With further miniaturization in the future, the process temperature will decrease,
If the film forming temperature is 800 ° C. or higher, there is a problem in matching with the semiconductor manufacturing process.

When a high dielectric film is used as a capacitor, it is considered effective to use a metal such as platinum so as not to oxidize the lower electrode, but these metals have poor adhesion to the base and are It can be said that a high-temperature process is a problem because there is a high risk of peeling when a high-temperature process of ℃ or higher is passed.

Furthermore, when a metal oxide film of high dielectric constant having a perovskite type crystal structure is formed by a CVD method using these halogen-containing organometallic compounds or metal halides as a raw material, the halogen causes impurities in the metal oxide film. Mixed as.

The mixing of such impurities acts to impede the formation of the perovskite type crystal structure, so that the dielectric constant and the insulating performance are deteriorated, and the original charge storage and holding capacity of the high dielectric film is significantly deteriorated. Cause.

Therefore, in a conventional DRAM using a high dielectric constant metal oxide film having a perovskite type crystal structure as the capacitor insulating film, the leakage current increases and the charge holding ability of the capacitor decreases, which results in reliability. There was a problem that the sex was impaired.

[0019]

As described above, the DR
The use of a metal oxide film having a high dielectric constant such as an oxide film having a perovskite structure or a transition metal oxide film as an insulating film requiring a high dielectric constant such as an AM capacitor insulating film has the following problems.

That is, in order to ensure good coverage, CV
When the film is formed by the D method, there is a problem that impurities generated by decomposition of the gas used for film formation are mixed into the metal oxide film, and the dielectric constant is lowered. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for forming a metal oxide film capable of preventing a decrease in the dielectric constant of the metal oxide film.

[0021]

In the present invention, a step of introducing a raw gas of a metal compound containing at least one of carbon and halogen into a film forming chamber, and a raw gas of an organic compound having a hydroxyl group in the film forming chamber Introducing a raw oxygen gas having an oxygen group into the discharge chamber, converting the raw oxygen gas into an oxygen plasma gas, and then introducing the oxygen plasma gas into the film forming chamber, There is provided a method for forming a metal oxide film by using a metal compound gas, an organic compound gas, and an oxygen plasma gas to form a metal oxide film in the film formation chamber by a CVD method.

The organic compound having a hydroxyl group is preferably an alcohol. It is preferable to introduce the organic compound gas into the film forming chamber in excess of the metal compound gas.

The metal oxide film has a perovskite crystal structure, particularly strontium titanate, barium titanate, calcium titanate, or 2 of these.
It is preferably composed of a mixture of three or more. The metal oxide film is preferably a superconductor film.

[0024]

As described above, when a H ₂ O / O ₂ mixed gas is used, a high temperature of 800 ° C. or higher is required, while an organic compound having a hydroxyl group such as alcohols is used as an oxidizing agent during film formation. In addition to this, when supplied to the film forming chamber, the halogen such as F is suppressed from binding to the metal and desorbed at a low temperature (500 to 800 ° C.), and as a result, a metal oxide is formed. As an example, ethanol (C ₂ H ₅
Bubbling (OH) with oxygen and supplying it to the reaction tank,
(Hfa) ₂ (hfa is an abbreviation for hexa fluoropentanedionate) and Ti (iso-C ₃ H ₇ O) ₄ as metal raw materials, when the strontium titanate film was formed, the ethanol / oxygen flow rate ratio and strontium titanate The relationship of the amount of F mixed in the film (shown by the ratio with respect to Sr) is shown in FIG. It can be seen from FIG. 4 that F is rapidly removed as the amount of alcohol is increased. Removal of F is a phenomenon that can be commonly expected in organic compounds having a hydroxyl group,
It was confirmed that F was removed by using any alcohol such as methyl alcohol, ethyl alcohol and n-propyl alcohol.

Further, the introduction amount of the organic compound gas having a hydroxyl group should be set to be larger than the total introduction amount of the metal compound gas containing at least one of carbon and halogen, especially halogen centered on F, that is, set excessively. Is particularly preferable, and in this case, the effect of removing F was remarkable.

However, using only alcohol C
When VD is performed, a large amount of C remains in the deposited strontium titanate film. As described above, the use of alcohol makes it possible to suppress the residual halogen such as F in the metal raw material at a low film forming temperature. However, when the halogen is removed by alcohol, as a result, the alcohol is removed as described above. C generated by the decomposition of C will be incorporated into the film. Fig. 5 shows an example of the situation in which Sr (hfa) ₂ is used as the Sr metal raw material. When the alcohol / oxygen ratio is increased to increase the F removal efficiency, the residual amount of C increases. , Up to a few atomic percent. This residual C causes a decrease in the dielectric constant in the case of a dielectric film, and a decrease in the superconducting transition temperature in the case of a superconductor film.

As described above, since alcohol is a halogen desorption accelerator, C generated by its decomposition is conversely taken into the film. Therefore, it is necessary to separately supply the oxidizing agent.

As a result of diligent research conducted by the present inventors, it was confirmed that when oxygen was once placed in a plasma state in the preceding stage of the reaction vessel and active oxygen free radicals were supplied, the residual amount of C was significantly reduced. The situation is also shown in FIG.

From the above, according to the present invention, a metal-organic CVD raw material having a high vapor pressure and a CVD containing halogen are used.
The raw material can be used to form a metal oxide having a high dielectric constant. Further, by forming this metal oxide film by the LPCVD method, it is possible to form it with good coverage. That is, when this metal oxide film is applied to the capacitor high dielectric film, a capacitor having a high charge retention ability can be obtained, and thus a highly reliable integrated circuit can be provided.

[0030]

Embodiments will be described below with reference to the drawings. Example 1 FIG. 1 shows a superconductor film (B) according to a first example of the present invention.
It is a schematic diagram which shows the schematic structure of the film-forming apparatus used in the film-forming method of (i-Sr-Ca-Cu-O).

In the figure, reference numeral 1 denotes a film forming chamber, which is evacuated by a vacuum pump 2. Inside the film forming chamber 1, the substrate 4 to be processed is placed on the heater 3 and heated.

The film forming chamber 1 is provided with several supply lines for supplying a reaction gas from the outside. That is, a raw material tank 5 in which Bi (C ₆ H ₅ ) ₃ which is a raw material of Bi is enclosed,
A raw material tank 6 containing Sr (hfa) ₂ which is a raw material of Sr, a raw material tank 7 containing Ca (hfa) ₂ which is a raw material of Ca, and Cu (hfa) ₂ which is a raw material of Cu.
Ar supply line 16 connected to the raw material tank 8 containing
And a tank 1 containing CH ₃ OH, which is a raw material for hydroxyl groups,
The first O ₂ supply line 17 and the second O ₂
A supply line and 18 are provided.

The Ar supply line 16 has mass flow controllers 9, 10, 1 for controlling the gas flow rate.
1, 12 are provided. Ar whose flow rate is controlled is
It is introduced into each raw material tank and vaporizes the raw material of each metal. The vaporized raw materials of the respective metals are collected in the gas mixing tank 19 and supplied to the film forming chamber 1 through the gas nozzle 20.

[0034] O ₂ supplied from the first O ₂ supply line
A mass flow controller 14 is provided in the. O ₂ whose flow rate is controlled is introduced into the tank 13 in which CH ₃ OH is sealed and vaporizes CH ₃ OH. This CH
₃ OH is supplied to the film forming chamber 1 through the gas nozzle 21.
Here, O ₂ was used as a carrier gas because CH ₃ O
This is because it mixes well with alcohols such as H.

[0035] O _2, which is supplied from the second O ₂ supply line
A mass flow controller 15 is provided in the. O ₂ having a controlled flow rate is introduced into the microwave discharge chamber 22 to generate oxygen free radicals. Oxygen free radicals generated by this discharge are supplied to the film forming chamber 1 through the gas nozzle 23.

Next, a method of forming a superconductor film (Bi-Sr-Ca-Cu-O) by the film forming apparatus having the above structure will be described. First, the temperature of the substrate 4 to be processed is set to 500 to 800 ° C. by the heater 3, the raw material tank 5,
6, 7, 8 for 120 ℃, 140 ℃, 140 ℃,
With the temperature kept at 140 ° C., the source gas (Bi (C ₆ H
₅ ) ₃ for 20 SCCM, Sr (hfa) ₂ for 50 SCC
M, Ca (hfa) ₂ at 50 SCCM, Cu (hfa)
₂₀ SCCM of ₂ was introduced into the film formation chamber 1 (temperature of the film formation chamber was 150 ° C., pressure was 133 Pa) together with a carrier gas (Ar).

Then, in the microwave discharge chamber 22, O ₂
O ₂ gas is introduced from the supply line 18 at a flow rate of 50 SCCM, microwave discharge of 9.45 GHz and 500 W is performed, and oxygen free radicals are introduced into the film forming chamber 1. Further, while maintaining the supply of oxygen free radicals, methanol (C
H ₃ OH) (flow rate 250 SCCM) and oxygen (flow rate 50)
A mixed gas of SCCM) was introduced into the film formation chamber in a system separate from that for oxygen free radicals and metal raw materials, and a superconductor film (Bi-Sr-Ca-Cu-O) was formed on the substrate 4 to be processed. .

According to the present invention, the impurities in the superconductor film were F at 0.1 atomic% or less and C at 0.2 atomic% or less, and the superconducting transition temperature was 100 K, which showed favorable characteristics. As in this embodiment, when the organometallic raw material is supplied into the film forming chamber 1, oxygen is once placed in a plasma state in the microwave discharge chamber 22 provided in the preceding stage of the film forming chamber 1. This is because free radicals of oxygen are generated by these, and these react instantaneously with the decomposition products, and the decomposition products can be effectively removed.

Further, by using alcohol, it becomes possible to suppress the residual halogen such as F in the metal raw material at a low film forming temperature. Furthermore, by using a raw material having a high vapor pressure such as Sr (hfa) _2, it has become possible to increase the film formation rate from the conventional 100 nm / h to 50 μm / h. Further, since the device temperature can be set to 150 ° C. or lower, it is possible to avoid the deterioration of the parts constituting the device.

On the substrate 4 to be processed, Bi-Sr-C is formed.
As a method of depositing a-Cu-O, metal organic chemical vapor deposition (MOCVD) was used. As the substrate 4 to be processed, magnesium oxide (MgO), strontium titanate (SrTiO ₃ ), yttria-stabilized zirconium (Y
A single crystal substrate to be processed such as SZ) or sapphire (Al ₂ O ₃ ) was used.

In this embodiment, Bi, Sr, Ca,
As a Cu raw material, Bi (C ₆ H ₅ ) ₃ and S are used, respectively.
r (hfa) ₂ , Ca (hfa) ₂ , Cu (hfa) ₂
However, other source gases may be used. For example, S
r raw material is Sr (fod) ₂ , SrI _2, etc., and Ca raw material is Ca (fod) ₂ (fod is fepta fluorodi
It is also possible to use nethyl octane dionate) or the like, and in these cases, it is possible to form a superconductor film (Bi—Sr—Ca—Cu—O) free from impurities.

In addition, another superconductor film (YB
a-Cu-O) has a superconducting transition temperature of 1
It was possible to realize a thin film of 00K, and to suppress the temperature of the organometallic raw material to 160 ° C. at the maximum, which made it possible to obtain good controllability of the apparatus.

In the present embodiment, the case where the microwave discharge is used to generate the plasma has been described, but the same effect can be obtained even if the discharge is formed by the RF discharge or another method. Embodiment 2 FIG. 2 is a process sectional view showing a method of manufacturing a DRAM according to a second embodiment of the present invention. Here, an example in which a strontium titanate film is applied to a capacitor insulating film of DRAM will be taken up.

First, as shown in FIG. 2A, an element isolation insulating film 35 for element isolation is formed on a single crystal silicon substrate 31 having a specific resistance of 10 Ω · cm and a main surface of (100) plane. did. Then, the silicon thermal oxide film is stripped off with hydrofluoric acid or the like to form a thin silicon thermal oxide film 36 to be a gate oxide film.
Was formed. Then, LP is formed on the single crystal silicon substrate 31.
Forming a first n ⁺ type polycrystalline silicon by a CVD method,
The gate electrode 37 was formed by patterning by a normal photo-etching method.

Next, ion implantation is performed on the single crystal silicon substrate 31 using the gate electrode 37 as a mask to form the n ^-- type source / drain diffusion layers 38 and 39 in a self-aligned manner. Next, after forming a thick CVD oxide film 40 on the entire surface of the substrate, the thick CVD oxide film 40 was patterned by a normal photoetching method to form an opening communicating with the source / drain diffusion layer 38. Next, a bit line 42 was formed by depositing tungsten silicide on the surfaces of the CVD oxide film 40 and the opening and then patterning it according to a normal photoetching method. After that, a CVD oxide film 43 was deposited on the entire surface of the substrate. Then, the silicon oxide film 4 is formed.
3. The silicon oxide film 40 was patterned by a normal photo-etching method to form an opening communicating with the source / drain diffusion layer 39.

Next, as shown in FIG. 2B, the second n
^{After the +} type polycrystalline silicon film 45 is deposited on the entire surface of the single crystal silicon substrate by the LPCVD method, the n ⁺ type polycrystalline silicon film 45 is left only inside the opening on the source / drain diffusion layer 39 by the etch back method. It was

Next, a molybdenum film 46 was deposited on the entire surface of the single crystal silicon substrate by a sputtering method and patterned by a usual photo-etching method. Furthermore, 500 ℃
Is annealed to oxidize the surface of molybdenum to form a capacitor lower electrode.

Next, a niobium-added strontium titanate film 47 is formed on the entire surface of the substrate by the CVD method. here,
In forming the niobium-added strontium titanate film 47, as source gases of Sr, Ti, and Nb, respectively,
Sr (hfa) ₂ with 100 SCCM, Ti (iso-OC ₃
H ₇ ) ₄ was supplied at 40 SCCM, Nb (OC ₂ H ₅ ) ₅ was supplied at about 1 to 2% of the total flow rate by bubbling these source gases with Ar gas. At this time, the film forming temperature is 150 ° C.,
The pressure in the film forming chamber was 133 Pa.

Next, the niobium-added strontium titanate film 47 was processed by the reactive ion etching method and left only on the titanium nitride film 46 of the lower electrode. Next, the strontium titanate film 48 was formed by the CVD method. Here, in forming the strontium titanate film 48, Sr (hf
a) ₂ was 100 SCCM, Ti (iso-OC ₃ H ₇ ) ₄ was 40 SCCM, and these source gases were bubbled and supplied with Ar gas. At this time, the film forming temperature was 150 ° C. and the film forming chamber pressure was 133 Pa.

Further, ethanol (C ₂ H ₅ OH) (flow rate 250) was used as a promoter for the elimination reaction of halogen in the metal raw material.
SCCM) was supplied into the reaction tank in a system different from that of the metal raw material.
Further, oxygen (flow rate 50 SCCM) as an oxidant was converted into plasma by microwave discharge of 2.45 GHz and 50 W in the preceding stage of the reaction tank to generate oxygen free radicals, which were supplied together with the above-mentioned source gas.

Finally, as shown in FIG. 2C, after a nickel film 49 to be a capacitor upper electrode is formed on the entire surface of the substrate by a CVD method, the nickel film 49 is patterned by a usual lithography technique and sputtering. As a result, the capacitor upper electrode is formed, and the basic structure of the memory cell is completed. After that, according to a normal LSI manufacturing process, a DRAM is completed through a passivation film forming step, a wiring forming step, and the like.

According to this embodiment, a metal oxide film serving as a capacitor insulating film can be formed without disturbing the perovskite type crystal structure, so that a capacitor having a high charge retention capability can be obtained, and a highly reliable DRAM can be obtained. can get.

Although the strontium titanate film is used as the capacitor insulating film in this embodiment, other high dielectric film such as PZT can be used instead of the strontium titanate film, and the electrode material can also be used. However, it is not limited to niobium-added strontium titanate and nickel. Further, the capacitor structure is not limited to the stacked capacitor structure, and the present invention can be applied to the trench capacitor structure.

Third Embodiment FIGS. 3A to 3D are process sectional views showing a method of manufacturing a DRAM according to a third embodiment of the present invention. Here, an example in which a barium titanate film is applied to a capacitor insulating film of DRAM will be taken up.

Similar to the second embodiment, first, as shown in FIG.
As shown in FIG. 1, a device isolation insulating film 35, a gate oxide film 36, a gate electrode 37, source / drain diffusion layers 38 and 39, a silicon oxide film 40 as a first interlayer insulating film, and a source on a single crystal silicon substrate 31. An opening communicating with the drain diffusion layer 38 and the bit line 42 were formed. Next, CV
A thick silicon oxide film 43, which is a second interlayer insulating film, was formed by the D method, and then an opening communicating with the source / drain 39 was formed.

Next, as shown in FIG. 3B, after forming an n ⁺ type polycrystalline silicon film 45 by the LPCVD method,
The n ⁺ type polycrystalline silicon film 45 was allowed to remain only inside the opening on the source / drain diffusion layer 39 by the etch back method.

Next, a tungsten film 46 ′ serving as a capacitor lower electrode was selectively grown on the entire surface of the substrate by the CVD method to partially protrude onto the silicon oxide film 43 to form a lower electrode.

Next, the surface of the tungsten film 46 'was oxidized to form tungsten trioxide 47'. next,
A barium titanate film 48 'was formed on the surface of the substrate by the CVD method. Here, in forming the tungsten trioxide film 47 ′ and the barium titanate film 48 ′, first, oxygen gas (flow rate 50 SCCM) was set at 2.45 G before the film formation chamber.
The surface of the tungsten film was changed to tungsten trioxide by supplying oxygen free radicals generated by being placed in a plasma state by microwave discharge of Hz and 200 W into the film forming chamber. At this time, since more active oxygen free radicals are used instead of normal oxygen,
Oxygen is prevented from being released during film formation, tungsten is kept in a peroxidized state, and tungsten trioxide can be formed. Further, the oxygen free radical has an effect of exhibiting a high dielectric constant in the barium titanate film by repairing defects such as oxygen vacancies in the barium titanate film.

Next, while maintaining the supply of oxygen free radicals (flow rate 50 SCCM), methanol (CH ₃ OH) (flow rate 250 SCCM) and oxygen (flow rate 50 SCCM) were further used as a desorption accelerator for halogen in the metal raw material. The mixed gas is introduced into the film forming chamber separately from the oxygen free radical and the metal raw material.

Next, a metal source was bubbled with Ar gas and introduced into the film forming chamber. As the source gas of Ba and Ti, Ba (hfa) ₂ (flow rate 100 SCCM), Ti
(Iso-OC ₃ H ₇ ) ₄ (flow rate 100 SCCM) was used.

As described above, when the organometallic raw material is supplied into the film forming chamber 1, oxygen is temporarily placed in a plasma state in the microwave discharge chamber 22 provided in the preceding stage of the film forming chamber 1 so that oxygen Free radicals were generated and these reacted instantly with the impurities, effectively removing the impurities.

Further, the use of alcohol makes it possible to suppress the residual halogen such as F in the metal raw material at a low film forming temperature. Finally, as shown in FIG. 3B, after forming a niobium film 49 'to be the capacitor upper electrode on the entire surface of the substrate by the sputtering method, the niobium film 49' is formed.
Is patterned by a normal photo-etching technique to form an upper electrode, and the basic structure of the memory cell is completed. After that, according to a normal LSI manufacturing process, a DRAM is completed through a passivation film forming step, a wiring forming step, and the like.

The present invention is not limited to the above embodiment. For example, in the embodiments, the case of forming a strontium titanate film or a barium titanate film was described, but the present invention is not limited to other high dielectric constant metal oxide films.
For example, it can be applied to the formation of a metal oxide film made of calcium titanate and a mixture of these three. That is, the present invention can be applied to film formation of a high dielectric film made of a substance containing at least one of Sr, Ba, Ca, Y, Cu, Ti, and Bi. It can also be applied to the formation of a high dielectric constant metal oxide film made of PZT, PLZT, or tantalum oxide. Furthermore, the present invention can be applied to a metal oxide film having a perovskite type crystal structure as a superconductor film.

Although ethanol and methanol are used in the above embodiment, other alcohols may be used.
Further, as long as it is a substance containing OH, it may not be alcohol.

Furthermore, in the above-mentioned embodiment, the semiconductor device has been described by taking the DRAM as an example, but the present invention can be applied to other semiconductor devices which require an insulating film having a high dielectric constant. In addition, various modifications can be made without departing from the scope of the present invention.

[0066]

As described above, according to the present invention,
In a method of forming a metal oxide film by a chemical vapor deposition method using a metal compound containing at least one of carbon and halogen, which has a relatively high vapor pressure and is thermally stable,
It is possible to prevent impurities such as carbon and halogen from being mixed into the metal oxide film.

Therefore, a high-quality metal oxide film, for example,
It becomes possible to stably form a film having a perovskite crystal structure having a high dielectric constant and a high insulating property by a CVD method, and by using this film as a capacitor insulating film of an integrated circuit, a highly reliable semiconductor device can be realized. . When the present invention is applied to a superconductor film, a superconductor film containing almost no impurities such as carbon and halogen (F etc.) can be formed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a film forming apparatus used in a method of forming a superconductor film according to a first embodiment of the present invention.

FIG. 2 is a process sectional view showing a method of manufacturing a DRAM according to a second embodiment of the present invention.

FIG. 3 is a process sectional view showing a method of manufacturing a DRAM according to a third embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the effect of the present invention.

FIG. 5 is a characteristic diagram showing the effect of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Film-forming chamber 2 ... Vacuum pump 3 ... Heater 4 ... Processed substrate 5, 6, 7, 8 ... Raw material tank 9, 10, 11, 12, 14, 15 ... Mass flow controller 13 ... Tank 16 ... Ar supply line 17 ... first O ₂ supply line 18 ... second O ₂ supply line 19 ... gas mixing tank 20, 21, 23 ... gas nozzle 22 ... microwave discharge chamber 31 ... single crystal silicon substrate 35 ... element isolation insulating film 36 ... Silicon thermal oxide film (gate oxide film) 37 ... Gate electrodes 38, 39 ... Source / drain diffusion layer 42 ... Bit line 43 ... Silicon oxide film 45 ... N ⁺ type polycrystalline silicon film 46 ... Molybdenum film 46 '... Tungsten film 47 ... Niobium-added strontium titanate film 47 '... Tungsten trioxide film 48 ... Strontium titanate film 48' ... Barium titanate film 49 ... Obumaku 49 '... nickel film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 27/04 21/822

Claims (7)

[Claims] 1. A step of directly introducing a metal compound gas containing at least one of carbon and halogen into a film forming chamber containing a substrate, and a step of directly introducing an organic compound gas having a hydroxyl group into the film forming chamber. A step of introducing a gas containing oxygen into the discharge chamber, plasmaizing the gas containing oxygen, and then introducing the gas containing oxygen into the film forming chamber, the metal compound gas, the organic compound gas A method for forming a metal oxide film, comprising forming a metal oxide film on the substrate by a CVD method in the film forming chamber using a gas containing oxygen which has been turned into plasma. 2. The method for forming a metal oxide film according to claim 1, wherein the organic compound having a hydroxyl group is an alcohol. 3. The method for forming a metal oxide film according to claim 1, wherein the organic compound gas is introduced into the film forming chamber in excess of the metal compound gas. 4. The method for forming a metal oxide film according to claim 1, wherein the halogen is fluorine. 5. The method for forming a metal oxide film according to claim 1, wherein the crystal structure of the metal oxide film is a perovskite structure. 6. The method for forming a metal oxide film according to claim 5, wherein the metal oxide film is made of strontium titanate, barium titanate, calcium titanate, or a mixture of two or more thereof. . 7. The method for forming a metal oxide film according to claim 1, wherein the metal oxide film is a superconductor film.