JPH09199500A - Method of forming silicon oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decelerate the oxidization rate for the formation of even and thin silicon oxide film by a method wherein, after the formation of a silicon oxide film on a semiconductor substrate in the atmosphere of humidified oxygen diluted with an inert gas, the silicon oxide film is heat-treated in the inert gas atmosphere containing halogen element. SOLUTION: A humidified oxygen is diluted with an inert gas made from nitrogen gas so as to oxidize a semiconductor substrate 11 in the atmosphere for the formation of the silicon oxide film 11. Next, the silicon oxide film 11 is heat-treated in the inert gas atmosphere containing halogen element so that the halogen atoms may be introduced into the silcon oxide film 11 either to remove any metallic impurities or to terminate the unpaired coupling of Si. Through these procedures, thin and even silicon oxide film having time zero dielectric breakdown(TZDB) characteristics and time dependent dielectric breakdown(TDDB) characteristics can be formed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for forming a silicon oxide film (SiO ₂ film) on a semiconductor substrate.

[0002]

2. Description of the Related Art In manufacturing a MOS type semiconductor device,
It is necessary to form a gate oxide film made of a silicon oxide film on the surface of the semiconductor substrate, and it is no exaggeration to say that the characteristics of this silicon oxide film play a role in the reliability of the MOS type semiconductor device. Therefore, the silicon oxide film is always required to have a high breakdown voltage.

As a method for forming a gate oxide film made of a silicon oxide film, there are a dry oxidation method and a humid oxidation method. Dry oxidation method, by supplying sufficiently dried oxygen to the surface of the heated silicon semiconductor substrate,
This is a method of forming a silicon oxide film on the surface of a silicon semiconductor substrate. Further, the humidification oxidation method is a method of forming a silicon oxide film on the surface of the silicon semiconductor substrate by supplying a high temperature carrier gas containing water vapor to the surface of the silicon semiconductor substrate. One of the humidification oxidation methods is a pyrogenic oxidation method. This method is a method of producing water by burning pure hydrogen in order to improve the reproducibility of the humidification oxidation method and eliminate the need to control the amount of water. The pyrogenic oxidation method has a lot of electron traps caused by water and thus is inferior in hot carrier resistance to the dry oxidation method, but is excellent in dielectric strength characteristics and long-term reliability of the silicon oxide film.

HCl, Cl ₂ , CCl ₄ , C ₂ HCl ₃ , C
When a silicon oxide film is formed by a dry oxidation method in an atmosphere containing a compound containing chlorine or other halogen elements such as H ₂ Cl ₂ and C ₂ H ₃ Cl ₃ , the following advantages can be obtained. Are known. In addition, such a method is hereinafter referred to as a hydrochloric acid oxidation method. (A) Neutralization or gettering of alkali metal impurities in the silicon oxide film (B) Reduction of stacking faults (C) Time-Zero Dielectric Breakdown, which is an index of dielectric breakdown evaluated in a short time TZ
DB) Improved characteristics (D) Improved channel mobility

On the other hand, the formed silicon oxide film is exposed to 800 to 100 in an inert gas such as nitrogen gas or argon gas.
It is known that heat treatment at 0 ° C. for about 30 minutes improves the following points at the interface between the silicon oxide film and the silicon semiconductor substrate. (E) Reduction of fixed charge (F) Reduction of interface state density

As an index of long-term reliability of a silicon oxide film, Time Dependent Dielectric Breakd
own, TDDB) characteristics. This time-dependent dielectric breakdown is a phenomenon in which the dielectric breakdown does not occur at the moment when the current stress or the voltage stress is applied, but the dielectric breakdown occurs in the silicon oxide film after a certain time has elapsed after the stress application.

The silicon oxide film formed by the wet oxidation method is superior to the silicon oxide film formed by the dry oxidation method in terms of dielectric breakdown (TDDB) characteristics. That is, it can be said that the silicon oxide film formed by the wet oxidation method has higher long-term reliability. This is because, -OH or -SiOH _X in the silicon oxide film is believed to be due to contribute to the improvement of the time-dependent dielectric breakdown (TDDB) characteristics.

The hydrochloric acid oxidation method, which is a kind of dry oxidation method, contributes to the improvement of the time-zero dielectric breakdown (TZDB) characteristic, but has a problem that the time-dependent dielectric breakdown (TDDB) characteristic cannot be improved. In addition, the hydrochloric acid oxidation method
There is also a problem that it is difficult to control the apparatus and oxide film forming conditions.

The silicon oxide film formed by the humid oxidation method has excellent TDDB characteristics over time as described above. When such a silicon oxide film is heat-treated in an inert gas such as nitrogen gas or argon gas, the above-mentioned improvements (E) and (F) are recognized, but time zero dielectric breakdown (TZDB) characteristics There is a problem that it is lower than the silicon oxide film formed by the hydrochloric acid oxidation method.

After the insulating film is formed, the insulating film is heat-treated in a reactive gas atmosphere containing chlorine, for example, and a method for forming an insulating film is disclosed in, for example, JP-A-3-2196.
No. 32 discloses this. In this insulating film forming method, the insulating film is formed by rapid heating with an infrared lamp. That is, the insulating film is formed by the so-called dry oxidation method. Therefore, there is a problem that the time-dependent dielectric breakdown (TDDB) characteristic of the silicon oxide film obtained by this insulating film forming method is inferior to the time-dependent dielectric breakdown (TDDB) characteristic of the silicon oxide film obtained by the humidification oxidation method. .
In addition, this insulating film forming method aims to reduce film defects caused by dangling bonds during the formation of the insulating film,
It is not intended to improve the time zero dielectric breakdown (TZDB) characteristic or the time-dependent dielectric breakdown (TDDB) characteristic. Furthermore, heat treatment is performed at 1000 ° C for 20 seconds, so-called RTA.
(Rapid Thermal Annealing) method is performed to form a doping layer of SiCl _X near the interface between the insulating film and the substrate.

As described above, according to the conventional dry oxidation method or humidification oxidation method, a silicon oxide film capable of satisfying both the time-zero dielectric breakdown (TZDB) characteristic and the time-dependent dielectric breakdown (TDDB) characteristic can be formed. Can not.

Therefore, the present applicant has filed Japanese Patent Application No. 5-8683.
No. 6 (see Japanese Patent Application Laid-Open No. 6-244173), time zero dielectric breakdown (TZDB) characteristics and time-dependent dielectric breakdown (T).
A method of forming a silicon oxide film having both excellent DDB) characteristics was proposed. In this method, a silicon oxide film is formed on a semiconductor substrate by a wet oxidation method, and then the silicon oxide film is heat-treated in an inert gas atmosphere containing a halogen element.

[0013]

With the high integration of MOS type semiconductor devices, it is required to reduce the thickness of the gate oxide film. For example, according to the "US Semiconductor Technology Roadmap" prepared by SIA, the thickness of the gate oxide film required for a MOS type semiconductor device having a gate length of 0.18 μm is 4.5 nm, and the thickness of the MOS type of 0.13 μm is required. The thickness of the gate oxide film required for the semiconductor device is actually expected to be 3.4 nm.

When a thin silicon oxide film is to be formed in this manner, the humidification oxidation method has a higher oxidation rate than the dry oxidation method. Therefore, it is necessary to reduce the oxidation temperature and shorten the oxidation time. However, there is a problem that lowering the oxidation temperature lowers the density of the silicon oxide film. Further, shortening the oxidation time has a problem in that uniformization of the thickness of the silicon oxide film is prevented. Therefore, when forming a thin silicon oxide film by adopting the humidification oxidation method, it is necessary to suppress the oxidation rate.

As a method of suppressing the oxidation rate, a diluted dry oxidation method or a diluted humidification oxidation method is known. In these methods, a silicon oxide film is formed in an atmosphere in which dry oxygen or humidified oxygen is diluted with an inert gas (mainly nitrogen gas or argon gas). However, since the dilute dry oxidation method is also essentially a dry oxidation method, the formed silicon oxide film has a larger leak current than the silicon oxide film formed by the humidification oxidation method, and thus has a long-term insulation property. Destruction (TDD
B) There are problems such as poor characteristics. On the other hand, since the diluted humidification oxidation method is essentially a humidification oxidation method, it has advantages such as a small leak current as compared with a silicon oxide film formed by a dry oxidation method, but it has a time zero dielectric breakdown. (TZD
B) Further improvement of characteristics is desired.

Therefore, an object of the present invention is to provide a method for forming a silicon oxide film which is excellent in time zero dielectric breakdown (TZDB) characteristics and time-dependent dielectric breakdown (TDDB) characteristics and which can form a thin and uniform silicon oxide film. To provide.

[0017]

According to the method of forming a silicon oxide film of the present invention for achieving the above object, a silicon oxide film is formed on a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas. After that, the silicon oxide film is heat-treated in an inert gas atmosphere containing a halogen element.

The inert gas for diluting the humidified oxygen is preferably nitrogen gas or argon gas. Further, it is preferable to obtain the humidified oxygen by the pyrogenic method, which is a method of burning pure hydrogen to produce water, in order to improve the reproducibility of the humidified oxidation method and to eliminate the need to control the water amount.

In the method of forming a silicon oxide film according to the present invention, the semiconductor substrate is heated to 600 to 1200 ° C., preferably 700, in an atmosphere in which humidified oxygen is diluted with an inert gas.
It is preferable to form a silicon oxide film on the surface of the semiconductor substrate by oxidizing the semiconductor substrate while being heated to 1000 to 1000 ° C., more preferably 800 to 900 ° C.

The heat treatment is preferably a furnace (furnace) annealing treatment. The heat treatment temperature is 600 to
The temperature is 1200 ° C, preferably 700 to 1000 ° C, more preferably 700 to 950 ° C. The heat treatment time is 5 to 60 minutes, preferably 10 to 40 minutes, and more preferably 20 to 30 minutes. Examples of the inert gas may include nitrogen gas and argon gas.

In the method for forming a silicon oxide film of the present invention, the halogen element contained in the inert gas atmosphere may be chlorine, bromine or fluorine, with chlorine being preferred. The form of the halogen element contained in the inert gas is, for example, HCl,
CCl ₄ , C ₂ HCl ₃ , CH ₂ Cl ₂ , C ₂ H ₃ Cl ₃ , Cl
₂ , Br ₂ , HBr, NF ₃ and SF ₆ can be mentioned. The content of the halogen element in the inert gas is 0.001 to 10% by volume, based on the form of the molecule or compound,
It is preferably 0.005 to 10% by volume, more preferably 0.01 to 10% by volume. For example, when using hydrochloric acid gas, the content of hydrochloric acid gas in the inert gas is 0.01 to 10
It is desirable that the content is% by volume.

The semiconductor substrate means not only the semiconductor substrate itself such as a silicon single crystal wafer but also the semiconductor substrate itself.
A semiconductor substrate on which an epitaxial layer, a polycrystalline layer, or an amorphous layer is formed, or a semiconductor substrate or a semiconductor element formed on these layers is used as a base for forming a silicon oxide film. means. Forming the silicon oxide film on the semiconductor substrate includes not only the case of forming the silicon oxide film on the semiconductor substrate but also the case of forming the silicon oxide film on the surface of the semiconductor substrate. The silicon semiconductor substrate may be manufactured by any method such as CZ method, MCZ method, DLCZ method and FZ method, or may be one to which hydrogen annealing has been added in advance.

The heat treatment method for a silicon oxide film of the present invention is performed by, for example, forming a gate oxide film of a MOS type transistor, an interlayer insulating film or an element isolation region, forming a gate oxide film of a top gate type or bottom gate type thin film transistor, a flash memory. The present invention can be applied to the formation of a silicon oxide film in various semiconductor devices such as the formation of a tunnel oxide film.

In the method of forming a silicon oxide film of the present invention, the silicon oxide film is formed by the humid oxidation method, so that the obtained silicon oxide film has a dielectric breakdown (TDD) over time.
B) Excellent in characteristics. Moreover, since the silicon oxide film is heat-treated in an inert gas atmosphere containing a halogen element,
The silicon oxide film has excellent time zero dielectric breakdown (TZDB) characteristics. Furthermore, since the silicon oxide film is formed on the semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas, a thin (particularly 10 nm or less) silicon oxide film can be formed uniformly.

[0025]

EXAMPLES A method for forming a silicon oxide film according to the present invention will be described below with reference to FIGS. 1 and 2 based on examples.

Example 1 In Example 1, a silicon oxide film was formed on the surface of a semiconductor substrate made of a silicon substrate by oxidizing the semiconductor substrate in an atmosphere in which humidified oxygen was diluted with an inert gas. Specifically, the humidified oxygen obtained by the conventional pyrogenic method is diluted with an inert gas composed of nitrogen gas, and the semiconductor substrate 10 is oxidized in such an atmosphere to form a silicon oxide film having a thickness of 3 nm. 11 was formed (see FIG. 1A). The flow rate ratio of hydrogen gas / oxygen gas / nitrogen gas was set to 1/1/8.
It should be noted that hydrogen gas and oxygen gas are mixed to 1/1, the hydrogen gas is burned to generate water vapor, and then diluted with nitrogen gas. The heating temperature of the semiconductor substrate during the formation of the silicon oxide film was 800 ° C. If necessary, before forming the silicon oxide film, the surface of the semiconductor substrate is cleaned (cleaning with chemicals or pure water, removal of the natural oxide film by heat treatment in a reducing gas atmosphere).

Next, the silicon oxide film 11 was heat-treated in an inert gas atmosphere containing a halogen element (see FIG. 1B). Specifically, the silicon oxide film was heat-treated under a heat treatment condition of 850 ° C. × 30 minutes in a nitrogen gas atmosphere containing 0.1% by volume of hydrochloric acid gas. A furnace was used for the heat treatment. In the oxidation device shown in FIG. 2 described later, a pipe for supplying an inert gas containing a halogen element to the heat treatment furnace 20 is provided separately,
The silicon oxide film may be heat-treated inside.

After that, the gate electrode 12 made of phosphorus-doped polysilicon is formed on the silicon oxide film 11 by using the known CVD technique, photolithography technique and dry etching technique (see FIG. 1C). ).
Thus, a so-called MOS capacitor was formed.

FIG. 2 is a schematic sectional view showing an example of an oxidizing device for forming a silicon oxide film by oxidizing a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas. This oxidation device includes a heat treatment furnace 20 for internally oxidizing a semiconductor substrate and a heat treatment furnace 2 via a pipe 40.
The water vapor generating means 30 connected to 0 and the inert gas supply pipe 41 connected to the pipe 40.

The heat treatment furnace 20 includes a processing chamber 21 and a processing chamber 2
1 is provided with a heater 22 arranged on the outer circumference. The processing chamber 21 has a structure in which, for example, a vertical cylindrical quartz tube is arranged in double. One end of the pipe 40 is connected to the processing chamber 21 of the heat treatment furnace 20, and the other end thereof is connected to the combustion chamber 31 of the steam generating means 30. An inert gas supply pipe 41 is connected in the middle of the pipe 40.

The steam generating means 30 includes a combustion chamber 31 made of quartz, a hydrogen gas supply pipe 32 and an oxygen gas supply pipe 33 inserted in the combustion chamber 31, and a hydrogen gas before the combustion chamber 31. Supply pipe 32 and oxygen gas supply pipe 33
The heating means 34 is disposed on the outer circumference of the.
Inside the combustion chamber 31, hydrogen gas and oxygen gas are reacted to generate water vapor. The generated water vapor is diluted with an inert gas (for example, nitrogen gas) from the inert gas supply pipe 41 on the way and supplied to the heat treatment furnace 20 through the pipe 40.

When forming a silicon oxide film on the surface of the semiconductor substrate 10, first, in the processing chamber 21 of the heat treatment furnace 20,
A plurality of semiconductor substrates 10 held in a quartz boat (not shown) are stored. Then, the heater 22 heats the inside of the processing chamber 21 to a predetermined temperature (for example, 800 ° C.).

After that, hydrogen gas and oxygen gas are supplied into the combustion chamber 31 at a ratio of 1/1 from the hydrogen gas supply pipe 32 and the oxygen gas supply pipe 33 of the steam generating means 30. At this time, hydrogen gas and oxygen gas heated to about 500 ° C. by the heating means 34 are supplied to the combustion chamber 31. As a result, inside the combustion chamber 31, the hydrogen gas and the oxygen gas undergo a combustion reaction to generate water vapor. Gas containing water vapor from the combustion chamber 31 is introduced into the pipe 40. Also,
From the inert gas supply pipe 41, an inert gas such as nitrogen gas is introduced into the pipe 40. The flow rate ratio of the inert gas was 8 times that of hydrogen gas. As a result, the gas containing water vapor from the combustion chamber 31 is diluted with the inert gas and introduced into the processing chamber 21 of the heat treatment furnace 20.
The introduced mixed gas (gas diluted with an inert gas) is heated to about 800 ° C. by the heater 22 arranged on the outer periphery of the processing chamber 21 and supplied to the surface of the semiconductor substrate 10. As a result, the surface of the semiconductor substrate 10 is oxidized and the silicon oxide film 11 is formed.

(Embodiment 2) The embodiment 2 is different from the embodiment 1 in that the flow rate ratio of hydrogen gas / oxygen gas / nitrogen gas is 1/1/16. The heating temperature of the semiconductor substrate at the time of forming the silicon oxide film and the heat treatment conditions of the silicon oxide film in the inert gas atmosphere containing the halogen element are the same as those in Example
The same as above.

Comparative Example In the comparative example, instead of heat-treating the silicon oxide film in an atmosphere of an inert gas containing a halogen element, the silicon oxide film was heat-treated in an atmosphere of an inert gas containing only nitrogen gas. However, it differs from the first embodiment. The flow rate ratio of hydrogen gas / oxygen gas / nitrogen gas at the time of forming the silicon oxide film is 1/1 as in the first embodiment.
/ 8. The heating temperature of the semiconductor substrate during the formation of the silicon oxide film was the same as in Example 1. Furthermore, the heat treatment conditions of the silicon oxide film in the atmosphere of only the inert gas,
Same as Example 1.

The time-dependent dielectric breakdown (TDDB) characteristics were evaluated by the following method. 50 MOSs on one semiconductor substrate 10
A capacitor was produced. The area of the gate electrode 12 formed on the silicon oxide film 11 was set to 0.1 mm ² . A circuit schematically shown in FIG. 3 is formed, and a constant Fowler-Nordheim current (J = 0.1 A) is applied to the silicon oxide film 11.
/ Cm ² ), a constant current TDDB method was used to measure the total amount of charges [so-called Coulomb breakdown (Q _BD )] that flowed in the silicon oxide film 11 until dielectric breakdown.
Here, Q _BD includes a J (A / cm ^2), determined by the product _{(Q B D = J × t} BD) of time t _BD until insulation breakdown.

Table 1 shows the failure rates (failure rates at the time of transition from the random failure period to the true failure period) obtained from the Q _BD measurement of the MOS capacitors manufactured according to Example 1, Comparative Example 1 and Comparative Example. .

[0038]

[Table 1]

The defective rate of Examples 1 and 2 is significantly lower than that of Comparative Example. This is because a halogen atom (specifically, chlorine) is introduced into the silicon oxide film by heat-treating the silicon oxide film in an atmosphere of an inert gas containing a halogen element, and as a result, a dielectric breakdown (TDDB) over time occurs. ) It is presumed that the metal impurities that cause the deterioration of the characteristics are removed or the unpaired bonds of Si are terminated.

The present invention has been described above based on the preferred embodiments, but the present invention is not limited to these embodiments. The conditions of the pyrogenic method and the conditions of the heat treatment, the thickness of the silicon oxide film, the type of the inert gas, the type and the form of the halogen element are examples, and can be appropriately changed.
As the humidification oxidation method, a conventional humidification oxidation method in which water vapor is mixed with a carrier gas such as oxygen or dry oxygen is passed through a water bubbler can be employed.

The silicon oxide film may be composed of a single layer or a plurality of layers. When the silicon oxide film is composed of a plurality of layers, any of the layers may be formed by the method for forming a silicon oxide film of the present invention. The remaining layer is formed by a conventional oxidation method such as a dry oxidation method including a hydrochloric acid oxidation method, a pressure oxidation method, a partial pressure oxidation method, a dilution oxidation method, a low temperature oxidation method, or an RTP (rapid thermal oxidation method). can do.

The oxidizer shown in FIG. 2 is an example, and the design can be changed appropriately. For example, in the oxidizing device shown in FIG. 4, the heating means 42 is arranged on the outer circumference of the inert gas supply pipe 41. By this heating means 42,
The inert gas passing through the inert gas supply pipe 41 can be heated to, for example, about 800 ° C. Therefore, in the pipe 40, the steam is mixed with the inert gas without being cooled by the inert gas, and this mixed gas (gas diluted with the inert gas) is supplied to the heat treatment furnace 20. Therefore, it is possible to prevent the impurities contained in the water vapor from precipitating as particles.
As a result, in the heat treatment furnace 20, the semiconductor substrate 10 is heat-treated in a mixed gas composed of only gas to form a silicon oxide film without particles adhering to the surface of the semiconductor substrate 10. Is possible. Furthermore, since the mixed gas supplied to the heat treatment furnace 20 is maintained at a heat treatment temperature of about 800 ° C., the semiconductor substrate 10 can be prevented from being cooled by the mixed gas. Therefore, inside the heat treatment furnace 20, it is possible to perform an oxidation process that suppresses variations in the growth rate of the silicon oxide film depending on the arrangement position of the semiconductor substrate 10.

In the oxidizing device shown in FIG. 5, an inert gas supply pipe 41 is connected to the combustion chamber 31 of the steam generating means 30. Therefore, in the combustion chamber 31, the combustion reaction of hydrogen gas and oxygen gas proceeds in the presence of the inert gas, and a mixed gas of water vapor and the inert gas is formed. Therefore, the water vapor is supplied to the heat treatment furnace 20 in a state of being contained in the mixed gas without being cooled. As a result, it is possible to prevent the impurities contained in the mixed gas from being deposited as particles. Therefore, in the heat treatment furnace 20, the semiconductor substrate 10 is heat-treated in a mixed gas composed of only gas, and the silicon oxide film can be formed without adhering particles. Further, since the mixed gas is generated by the combustion reaction and is heated to a predetermined temperature by the reaction heat, the variation in the growth rate of the silicon oxide film depending on the arrangement position of the semiconductor substrate 10 is suppressed inside the heat treatment furnace 20. Oxidation treatment can be performed.

In the oxidizer shown in FIG. 6, the inert gas supply pipe 41 has the hydrogen gas supply pipe 3 upstream of the heating means 34.
2 are connected. As a result, similar to the oxidizing device shown in FIG. 5, in the combustion chamber 31, the combustion reaction of hydrogen gas and oxygen gas proceeds in the presence of the inert gas, and a mixed gas of water vapor and the inert gas is formed. . The inert gas supply pipe 41 may be connected to the oxygen gas supply pipe 33 upstream of the heating means 34. With such a configuration,
Similar to the oxidizer shown in FIG. 5, it is possible to prevent particles from being deposited in the mixed gas.

[0045]

The silicon oxide film formed by the method for forming a silicon oxide film according to the present invention has a greater effect than the conventional wet oxidation method or dry oxidation method, that is, the hydrochloric acid oxidation method.
It has excellent time-zero dielectric breakdown (TZDB) characteristics and time-dependent dielectric breakdown (TDDB) characteristics. Further, since the silicon oxide film is formed on the semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas, the oxidation rate can be suppressed, and a uniform and thin silicon oxide film can be formed reliably and easily. You can

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of a semiconductor substrate or the like for explaining a method for forming a silicon oxide film of the present invention.

FIG. 2 is a schematic cross-sectional view of an example of an oxidation device for forming a silicon oxide film by oxidizing a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas.

FIG. 3 is a schematic diagram of a circuit used for evaluation of time-dependent dielectric breakdown (TDDB) characteristics.

FIG. 4 is a schematic cross-sectional view of another example of an oxidation device for forming a silicon oxide film by oxidizing a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas.

FIG. 5 is a schematic cross-sectional view of still another example of an oxidation device for forming a silicon oxide film by oxidizing a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas.

FIG. 6 is a schematic cross-sectional view of yet another example of an oxidation device for forming a silicon oxide film by oxidizing a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas.

[Explanation of symbols]

10 ... Semiconductor substrate, 11 ... Silicon oxide film, 1
2 ... Gate electrode, 20 ... Heat treatment furnace, 21 ...
Processing chamber, 22 ... Heater, 30 ... Steam generating means, 31 ... Combustion chamber, 32 ... Hydrogen gas supply pipe, 3
3 ... Oxygen gas supply pipe, 34 ... Heating means, 40 ...
..Piping, 41 ... Inert gas supply pipe, 42 ... Heating means

Claims (8)

[Claims] 1. A silicon oxide film is formed on a semiconductor substrate in an atmosphere in which humidified oxygen is diluted with an inert gas, and then the silicon oxide film is heat-treated in an inert gas atmosphere containing a halogen element. A method for forming a silicon oxide film. 2. The method for forming a silicon oxide film according to claim 1, wherein the inert gas for diluting the humidified oxygen is nitrogen gas or argon gas. 3. The method for forming a silicon oxide film according to claim 2, wherein the humidified oxygen is obtained by a pyrogenic method. 4. A silicon oxide film is formed on the surface of a semiconductor substrate by oxidizing the semiconductor substrate while heating the semiconductor substrate to 600 to 1200 ° C. in an atmosphere in which humidified oxygen is diluted with an inert gas. The method for forming a silicon oxide film according to claim 1, wherein. 5. The method for forming a silicon oxide film according to claim 1, wherein the heat treatment is a furnace annealing treatment. 6. The method for forming a silicon oxide film according to claim 5, wherein the heat treatment is performed at a temperature of 600 to 1200 ° C. 7. The method for forming a silicon oxide film according to claim 1, wherein the halogen element contained in the inert gas atmosphere is chlorine. 8. The silicon oxide film according to claim 7, wherein the chlorine is in the form of hydrochloric acid, and the concentration of hydrochloric acid contained in the inert gas atmosphere is 0.01 to 10% by volume. Forming method.