JPH1167747A - Formation of silicon oxide film and device for forming oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the formation of a dry oxide film on a surface by supplying inert gas when steam is generated in a combustion chamber by the supply of hydrogen gas, keeping the temperature, at which silicon atoms are not desorbed, forming a silicon oxide film, increasing the temperature, and further forming the silicon oxide film. SOLUTION: The substrate having a silicon layer is arranged in a processing chamber 10 of inactive gas atmosphere, wherein the temperature is maintained so that silicon atoms are not desorbed. Then, after at least the supply of oxygen gas into a combustion chamber 30 is started, steam is generated in the combustion chamber 30 by the supply of hydrogen gas into the combustion chamber 30. Until the time when the steam is supplied into the processing chamber 10, inactive gas is supplied into the processing chamber 10. Thus, the concentration of the oxygen gas in contact with the silicon layer can be sufficiently decreased before the silicon oxide film is formed by the steam. The formation of the silicon oxide film by the oxigen gas (formation of the dry oxide film) can be controlled.

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 silicon oxide film in the manufacture of a semiconductor device, and an oxide film forming apparatus suitable for implementing the method for forming a silicon oxide film.

[0002]

2. Description of the Related Art For example, in a MOS type semiconductor device,
The silicon oxide film is used for a gate oxide film, an element isolation region, an interlayer insulating film, and the like. These silicon oxide films are formed based on a vapor deposition method, a thermal oxidation method, a sputtering method, or the like. In particular, it is not an exaggeration to say that an ultra-thin silicon oxide film having a thickness of several nm to several tens of nm used as a gate oxide film is responsible for the reliability of a semiconductor device. Therefore,
The silicon oxide film is always required to have high dielectric breakdown voltage and long-term reliability. Therefore, such a silicon oxide film is
Usually, it is formed based on a thermal oxidation method having excellent interface characteristics and excellent film thickness controllability.

[0003] For example, in the case of manufacturing a MOS type semiconductor device, conventionally, NH ₄ OH /
The surface of the silicon semiconductor substrate is cleaned by RCA cleaning in which the surface is washed with an H ₂ O ₂ aqueous solution and further washed with an HCl / H ₂ O ₂ aqueous solution, and fine particles and metal impurities are removed from the surface. When the RCA cleaning is performed, the surface of the silicon semiconductor substrate reacts with the cleaning liquid to form a silicon oxide film having a thickness of about 0.5 to 1 nm (hereinafter, such a silicon oxide film is simply referred to as an oxide film). The thickness of such an oxide film is not uniform, and the cleaning liquid component remains in the oxide film. Therefore, the silicon semiconductor substrate is immersed in a hydrofluoric acid aqueous solution to remove such an oxide film, and further, a chemical component is removed with pure water to expose a clean surface of the silicon semiconductor substrate. Thereafter, the silicon semiconductor substrate is carried into a processing chamber (oxidizing furnace) of an oxide film forming apparatus, and a silicon oxide film is formed on the surface of the silicon semiconductor substrate. Most of the surface of the silicon semiconductor substrate after the cleaning with the hydrofluoric acid aqueous solution is terminated with hydrogen, and a very small portion is terminated with fluorine.

As an oxide film forming apparatus, as a gate oxide film becomes thinner and a substrate becomes larger in diameter, a quartz type processing chamber (oxidizing furnace) is held horizontally and a vertical type is held vertically. Are shifting to oxide film forming apparatuses. This is because the vertical-type oxide film forming apparatus is easier to cope with the enlargement of the substrate than the horizontal-type oxide film forming apparatus, and also when the silicon semiconductor substrate is carried into the processing chamber. This is because a silicon oxide film generated by entrainment in the atmosphere (hereinafter, such a silicon oxide film is referred to as a natural oxide film) can be reduced. However, even when a vertical oxide film forming apparatus is used, a natural oxide film having a thickness of about 2 nm is formed on the surface of the silicon semiconductor substrate. The natural oxide film contains a large amount of impurities in the atmosphere, and the existence of the natural oxide film cannot be ignored in thinning the gate oxide film. Therefore, (1) a method of flowing a large amount of nitrogen gas to a substrate loading / unloading section provided in an oxide film forming apparatus to form a nitrogen gas atmosphere (nitrogen gas purge method), (2)
Once the inside of the substrate loading / unloading section is evacuated, a method of replacing the inside of the substrate loading / unloading section with nitrogen gas or the like to eliminate the atmosphere (vacuum load lock method) or the like is adopted, and the formation of a natural oxide film is suppressed as much as possible. A method has been proposed.

[0005] Then, the silicon semiconductor substrate is carried into the processing chamber (oxidizing furnace) with the processing chamber (oxidizing furnace) in an inert gas atmosphere, and then the processing chamber (oxidizing furnace) is oxidized. The gate oxide film is formed by switching and heat-treating the silicon semiconductor substrate. A method of thermally oxidizing the surface of a silicon semiconductor substrate by introducing high-purity water vapor into a processing chamber maintained at a high temperature (wet oxidation method) is used for forming a gate oxide film. A gate oxide film with higher electrical reliability can be formed than a method of oxidizing the surface of a silicon semiconductor substrate with oxygen gas (dry oxidation method). As one of the wet oxidation methods, there is a pyrogenic oxidation method (also referred to as a hydrogen combustion oxidation method) using water vapor generated by mixing hydrogen gas with oxygen gas at a high temperature and burning the mixture. Usually, in this pyrogenic oxidation method, the pyrogen oxidation method is provided outside a processing chamber (oxidizing furnace), and
Oxygen gas is introduced into the combustion chamber maintained at 0 to 900 ° C., and then hydrogen gas is introduced into the combustion chamber to burn the hydrogen gas at a high temperature. The water vapor thus obtained is used as an oxidizing species.

FIG. 34 is a conceptual diagram of a conventional vertical type oxide film forming apparatus for forming a silicon oxide film by a pyrogenic oxidation method. The vertical type oxide film forming apparatus includes a processing chamber 10 composed of a furnace core tube having a double tube structure made of quartz and held vertically, and a gas introduction unit for introducing water vapor and the like into the processing chamber 10. 12, a gas exhaust unit 13 for exhausting gas from the processing chamber 10, a cylindrical soaking tube 14 made of SiC, and a heater 15 for maintaining the inside of the processing chamber 10 at a predetermined atmospheric temperature via the soaking tube 14. A substrate loading / unloading section 20, a gas introducing section 21 for introducing nitrogen gas into and out of the substrate loading / unloading section 20, a gas exhaust section 22 for exhausting gas from the substrate loading / unloading section 20, a processing chamber 10, and a substrate loading / unloading section. Part 2
The shutter 16 is provided with an elevator mechanism 23 for carrying the silicon semiconductor substrate into and out of the processing chamber 10. A quartz boat 24 for mounting a silicon semiconductor substrate is attached to the elevator mechanism 23. Further, the combustion chamber 30 is connected via the pipes 31 and 32.
The hydrogen gas and the oxygen gas supplied to the combustion chamber 30 are mixed at a high temperature in the combustion chamber 30 and burned to generate steam. The water vapor is supplied into the processing chamber 10 via the pipe 33, the gas flow path 11, and the gas introduction unit 12.
The gas flow path 11 corresponds to a space between the inner wall and the outer wall of the processing chamber 10 having a double pipe structure.

An outline of a conventional method for forming a silicon oxide film based on a pyrogenic oxidation method using the conventional vertical type oxide film forming apparatus shown in FIG. 34 is shown in FIGS.
This will be described below with reference to FIG.

[Step-10] Nitrogen gas is introduced into the processing chamber 10 through the pipe 31, the combustion chamber 30, the pipe 33, the gas flow path 11 and the gas introduction unit 12, and the inside of the processing chamber 10 is set to a nitrogen gas atmosphere. At the same time, the atmosphere temperature in the processing chamber 10 is maintained at 700 to 800 ° C. by the heater 15 via the soaking tube 14. In this state, the shutter 16 is closed (see FIG. 35A). The substrate loading / unloading section 20 is open to the atmosphere.

[Step-20] The substrate loading / unloading section 20
Then, the silicon semiconductor substrate 40 is carried in, and the silicon semiconductor substrate 40 is placed on the quartz boat 24. Substrate loading / unloading section 20
After the loading of the silicon semiconductor substrate 40 into the substrate loading / unloading unit 20 is completed, a door (not shown) is closed, nitrogen gas is introduced into the substrate loading / unloading unit 20 from the gas introduction unit 21, exhausted from the gas exhaust unit 22, and exhausted from the substrate loading / unloading unit 20. In a nitrogen gas atmosphere (see FIG. 35B).

[Step-30] When the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere, the shutter 16 is opened (see FIG. 36B), the elevator mechanism 23 is operated, and the quartz boat 24 is operated. Is raised, and the silicon semiconductor substrate 40 is carried into the processing chamber 10 (see FIG. 37A). When the elevator mechanism 23 reaches the ascending position, the processing chamber 10 and the substrate loading / unloading section 20 are not communicated by the base of the quartz boat 24.

If the processing chamber 10 is left in a nitrogen gas atmosphere before the shutter 16 is opened, the following problems occur. That is, when the silicon semiconductor substrate whose surface is exposed with the hydrofluoric acid aqueous solution is carried into a high-temperature nitrogen gas atmosphere, the surface of the silicon semiconductor substrate 40 becomes rough. This phenomenon is caused by the fact that the Si—H bond formed on the surface of the silicon semiconductor substrate 40 by washing with the hydrofluoric acid aqueous solution is
Loss due to thermal desorption of hydrogen, silicon semiconductor substrate 4
This is considered to be caused by the occurrence of an etching phenomenon on the surface of No. 0. For example, when the temperature of a silicon semiconductor substrate is raised to 600 ° C. or more in argon gas, severe irregularities may occur on the surface of the silicon semiconductor substrate. Have been. In order to suppress such a phenomenon,
Before opening the shutter 16, oxygen gas is introduced from the pipe 32 into the combustion chamber 30, and, for example, nitrogen gas containing about 0.5% by volume of oxygen gas is introduced into the pipe 33, the gas passage 11, and the gas introduction unit. The processing chamber 10 is introduced into the processing chamber 10 through the atmosphere 12, and the inside of the processing chamber 10 is set to a nitrogen gas atmosphere containing about 0.5% by volume of oxygen gas (see FIG. 36A).

[Step-40] Thereafter, the atmosphere temperature in the processing chamber 10 is set to 800 to 900 ° C. Then, before introducing steam into the processing chamber 10, the piping 31, the combustion chamber 30,
The introduction of nitrogen gas through the pipe 33, the gas flow path 11 and the gas introduction unit 12 is stopped, and at the same time, the introduction of oxygen gas from the pipe 32 into the combustion chamber 30 is continued, so that the inside of the combustion chamber 30 is filled with oxygen gas. Thus, it is possible to prevent the detonation reaction from occurring due to the incompletely burned hydrogen gas being introduced into the processing chamber 10. As a result, oxygen gas flows into the processing chamber 10 through the combustion chamber 30, the pipe 33, the gas flow path 11, and the gas introduction unit 12 (see FIG. 37B). The temperature in the combustion chamber 30 is controlled by, for example, a heater (not shown).
It is kept at 00 to 900 ° C.

[Step-50] Next, hydrogen gas is introduced into the combustion chamber 30 from the pipe 31, and the hydrogen gas and the oxygen gas are mixed at a high temperature in the combustion chamber 30 and the steam generated by the combustion is removed. , A pipe 33, a gas flow path 11, and a gas introduction unit 12, and the gas exhaust unit 1
3 is exhausted (see FIG. 38). Thus, a silicon oxide film is formed on the surface of the silicon semiconductor substrate 40.

[0014]

As described above, before burning the hydrogen gas, it is necessary to sufficiently fill the region into which the hydrogen gas is introduced with oxygen gas in advance in order to prevent a detonation reaction. . However, in the vertical type oxide film forming apparatus shown in FIG. 34, since oxygen gas flows into the processing chamber 10 from the gas introduction unit 12 in [Step-40], the silicon oxide film is formed by the pyrogenic oxidation method. Before forming the silicon oxide film, a silicon oxide film (dry oxide film) is formed by so-called dry oxidation using dry oxygen gas. For example, when the atmosphere temperature in the processing chamber 10 is set to 800 ° C. and oxygen gas is flown into the processing chamber 10 for 1 minute before introducing hydrogen gas, a dry oxide film having a thickness of 1 to 1.5 nm is formed. Would.

In the conventional semiconductor device, the ratio of the thickness of the dry oxide film to the thickness of the silicon oxide film finally formed is sufficiently small, so that the dry oxide film affecting the electrical reliability of the semiconductor device is reduced. Was able to ignore the effects. However, with the miniaturization and high integration of the semiconductor device, the thickness of the gate oxide film has been reduced. It is expected that a membrane will be used. Therefore, the ratio of the thickness of the dry oxide film to the silicon oxide film is increasing, and the influence of the dry oxide film on the electrical reliability of the semiconductor device cannot be ignored. Therefore, with the conventional method for forming a silicon oxide film using the conventional oxide film forming apparatus shown in FIG. 34, it is difficult to manufacture a semiconductor device having a silicon oxide film with excellent electrical reliability.

The above problem occurs not only on the surface of a silicon semiconductor substrate but also on the surface of a silicon layer provided on an insulating substrate or the like.

Accordingly, an object of the present invention is to reduce the formation of a dry oxide film on the surface of a silicon layer when forming a silicon oxide film on the surface of a silicon layer.
In addition, it is an object of the present invention to provide a silicon oxide film forming method capable of forming a silicon oxide film having excellent characteristics, and an oxide film forming apparatus suitable for performing the silicon oxide film forming method.

[0018]

According to the present invention, there is provided a method for forming a silicon oxide film, comprising: (A) a combustion chamber for generating steam by burning hydrogen gas with an oxygen gas; A method for forming a silicon oxide film using an oxide film forming apparatus, comprising: a treatment chamber that communicates with a combustion chamber and forms a silicon oxide film on a surface of a silicon layer with water vapor supplied from the combustion chamber, (A) After disposing a substrate having a silicon layer in a processing chamber in an inert gas atmosphere maintained at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer, at least after starting supply of oxygen gas to the combustion chamber, An inert gas is supplied into the processing chamber until steam is generated in the combustion chamber by the supply of the hydrogen gas to the combustion chamber and supplied to the processing chamber, and then the silicon source is supplied from the surface of the silicon layer. Forming a silicon oxide film on the surface of the silicon layer in a state where but holding the atmosphere eliminated without temperature by steam supplied from the combustion chamber,
(B) a step of raising the temperature of the atmosphere in the processing chamber to a desired temperature; and (c) further forming a silicon oxide film with water vapor supplied from the combustion chamber while maintaining the atmosphere at the desired temperature. Performing the steps of:
FIG. 1 schematically shows a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas. In the figure, "ON" and "OF" of the inert gas, oxygen gas, and hydrogen gas are respectively shown.
The indication "F" indicates the introduction or non-introduction of those gases into the processing chamber or the combustion chamber. Further, the step of forming a silicon oxide film on the surface of the silicon layer with water vapor in the step (a) is referred to as a first silicon oxide film forming step, the step (b) is referred to as a temperature increasing step, and the silicon in the step (c) is referred to as a first step. The step of forming an oxide film is called a second silicon oxide film forming step. The same applies to the following.

In the method for forming a silicon oxide film according to the present invention, in the step (a), a substrate having a silicon layer in a processing chamber in an inert gas atmosphere maintained at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer. After the oxygen gas is supplied to the combustion chamber, at least until the steam is generated in the combustion chamber by the supply of hydrogen gas to the combustion chamber and supplied to the processing chamber, the inert gas is introduced into the processing chamber. Supply gas. Thus, before the silicon oxide film is formed by the water vapor, the concentration of the oxygen gas in contact with the silicon layer can be sufficiently reduced, and the formation of the silicon oxide film (the formation of the dry oxide film) by the oxygen gas can be suppressed. It becomes possible.

Further, a silicon oxide film is formed on the surface of the silicon layer by an oxidation method using water vapor while maintaining an atmosphere at a temperature at which silicon atoms do not desorb from the surface of the silicon layer. Since the atmosphere is maintained at such a temperature, detachment of Si—O and nitridation of the silicon layer can be suppressed. As a result, unevenness (roughness) on the surface of the silicon layer can be prevented. Furthermore, since the oxidation reaction in the silicon layer can start not from the Si-H bond on the surface but from the Si-Si-H bond inside one layer, the silicon oxidation is performed in a state where the flatness of the interface is maintained at the atomic level. The formation of the film can begin. In addition, since the silicon oxide film is formed on the surface of the silicon layer by an oxidation method using water vapor, it is possible to suppress the dry oxide film from being included in the finally formed silicon oxide film, and to obtain excellent characteristics. Can be formed.

Further, with a silicon oxide film already functioning as a protective film already formed on the surface of the silicon layer, the temperature is raised to a desired temperature, the atmosphere is maintained at that temperature, and an oxidation method using steam is used. Further, since the silicon oxide film is formed, no irregularities (roughness) are generated on the surface of the silicon layer even when the temperature raising step is performed in a non-oxidizing atmosphere. Further, a silicon oxide film having excellent characteristics can be formed.

In the method of forming a silicon oxide film according to the present invention, since the silicon oxide film is formed by an oxidation method using water vapor, excellent time-dependent dielectric breakdown (TDDB) is achieved.
A silicon oxide film having characteristics can be obtained.

The characteristics of the silicon oxide film formed in the step (a) usually do not sufficiently satisfy the characteristics required for a gate oxide film, for example. By further forming a silicon oxide film in the step (c), a silicon oxide film which sufficiently satisfies the characteristics required as a gate oxide film can be obtained. The final thickness of the silicon oxide film after the step (c) may be a predetermined thickness required for the semiconductor device. On the other hand, the thickness of the silicon oxide film after the step (a) is preferably as thin as possible. However,
At present, the plane orientation of a silicon semiconductor substrate used for manufacturing a semiconductor device is almost (100), and no matter how smooth the surface of the silicon semiconductor substrate is, the (100) silicon surface always has a step. A so-called step is formed. This step is usually for one layer of silicon atoms, but in some cases, a step for two to three layers may be formed. Therefore, the thickness of the silicon oxide film after the step (a) is preferably 1 nm or more when a (100) silicon semiconductor substrate is used as the silicon layer.

In the method of forming a silicon oxide film according to the present invention, in the step (a), after the silicon oxide film is formed on the surface of the silicon layer, the supply of hydrogen gas to the combustion chamber is stopped for a predetermined time. An embodiment in which the inert gas is supplied into the processing chamber while supplying the oxygen gas to the combustion chamber may be adopted. FIG. 2 schematically shows a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in this case.

Alternatively, in the step (c), before the formation of the silicon oxide film by the water vapor, at least after the start of the supply of the oxygen gas to the combustion chamber, the supply of the hydrogen gas to the combustion chamber causes the combustion of the water vapor. An embodiment in which the inert gas is supplied into the processing chamber until it is generated in the chamber and supplied to the processing chamber may be adopted. FIG. 3 schematically shows a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in this case.

Further, in the step (c), after forming a silicon oxide film on the surface of the silicon layer, stopping supply of hydrogen gas to the combustion chamber, supplying oxygen gas to the combustion chamber for a predetermined time. Alternatively, an aspect in which an inert gas is supplied into the processing chamber may be adopted. FIG. 4 schematically shows a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in this case.

FIG. 5 shows a gas introduction sequence obtained by combining the gas introduction sequences shown in FIGS. 2 and 3.
FIG. 6 shows a gas introduction sequence obtained by combining the gas introduction sequences shown in FIGS. 2 and 4. FIG. 7 shows a gas introduction sequence obtained by combining the gas introduction sequences shown in FIGS. 3 and 4. FIG. 8 shows a gas introduction sequence obtained by combining the gas introduction sequences shown in FIGS. 2, 3, and 4.

According to each of these aspects, formation of a silicon oxide film (formation of a dry oxide film) by oxygen gas can be more reliably suppressed.

The steam may be diluted with an inert gas. FIG. 9 shows a gas introduction sequence in the case where water vapor is continuously diluted with an inert gas in the gas introduction sequence shown in FIG. Further, steam may be diluted with an inert gas only in one of the first silicon oxide film forming step and the second silicon oxide film forming step. The gas introduction sequences in these cases are shown in FIGS. As described above, by diluting the water vapor with the inert gas, it is possible to suppress the rapid formation of the silicon oxide film, it is possible to enhance the controllability of the thickness of the silicon oxide film, and it is possible to more reliably reduce the thickness of the silicon oxide film. A silicon oxide film can be formed.

Here, as the inert gas, nitrogen gas,
Examples thereof include an argon gas and a helium gas.
In the method of forming a silicon oxide film of the present invention or various aspects thereof, oxygen gas is supplied into a processing chamber in order to prevent incomplete combustion of hydrogen gas.

In the step (a), when the substrate having the silicon layer is placed in the processing chamber, the temperature of the inert gas atmosphere in the processing chamber is the same as the temperature at which the silicon oxide film is formed on the surface of the silicon layer by water vapor. It may be the same as or lower than the temperature. The ambient temperature when the silicon oxide film is formed on the surface of the silicon layer by the water vapor may be constant or may be changed.

In the method for forming a silicon oxide film of the present invention, the temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which the bond between the atoms terminating the silicon layer surface and the silicon atoms is not broken. Is desirable.
In this case, the temperature at which silicon atoms do not desorb from the surface of the silicon layer is preferably a temperature at which a Si—H bond is not broken or a temperature at which a Si—F bond is not broken. The temperature at which silicon atoms do not desorb from the surface of the silicon layer is a value measured at 1.013 × 10 ⁵ Pa (1 atm), and is higher than the temperature at which water vapor does not condense on the silicon layer, preferably 100 ° C. C or more, more preferably 20
It is desirable that the temperature be 0 ° C. or higher and 430 ° C. or lower, preferably 400 ° C. or lower.

The water vapor in the step (a) and / or the step (c) may contain a halogen element. As a result, a silicon oxide film having excellent time zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained. As halogen elements, chlorine, bromine,
Fluorine can be mentioned, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the water vapor include hydrogen chloride (HCl), CCl ₄ ,
It can be exemplified _{C 2 HCl 3, Cl 2,} HBr, NF 3. The content of the halogen element in the water vapor is 0.001 to 10% by volume, preferably 0.005 to 10% by volume, and more preferably 0.05 to 10% by volume, based on the form of the molecule or the compound.
It is 2 to 10% by volume. For example, when hydrogen chloride gas is used, the content of hydrogen chloride gas in water vapor is desirably 0.02 to 10% by volume.

In the method for forming a silicon oxide film of the present invention, it is desirable that the atmosphere in the step (b) be an inert gas atmosphere or a reduced pressure atmosphere, or an oxidizing atmosphere containing water vapor. FIG. 12 shows the gas introduction sequence in the latter case. In the latter case, the steam may be further diluted with an inert gas. In the gas introduction sequence shown in FIG. 12, a gas introduction sequence in the case where water vapor is continuously diluted with an inert gas is shown in FIG.
3 is shown. Further, steam may be diluted with an inert gas only in one of the first silicon oxide film forming step and the second silicon oxide film forming step. The gas introduction sequence in these cases is shown in FIGS. As described above, by diluting the water vapor with the inert gas, it is possible to suppress the rapid formation of the silicon oxide film, it is possible to enhance the controllability of the thickness of the silicon oxide film, and it is possible to more reliably reduce the thickness of the silicon oxide film. A silicon oxide film can be formed. In addition, a silicon oxide film is also formed in the temperature raising step, but the in-plane thickness variation of the silicon oxide film can be reduced by diluting water vapor with an inert gas. Here, examples of the inert gas include a nitrogen gas, an argon gas, and a helium gas. Incidentally, the inert gas or water vapor in the atmosphere in the step (b) may contain a halogen element. Thereby, the characteristics of the silicon oxide film formed in the step (a) can be further improved. That is, the silicon dangling bonds (Si.) And SiOH, which are defects that can occur in the step (a), react with the halogen element in the step (b) to terminate the silicon dangling bonds or cause a dehydration reaction, resulting in reliability. These defects, which are deterioration factors, are eliminated. In particular, the elimination of these defects is effective for the initial silicon oxide film formed in the step (a). In addition, as the halogen element, chlorine, bromine and fluorine can be mentioned, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the inert gas or steam include hydrogen chloride (HCl), CCl ₄ , and C ₂ HCl.
₃ , Cl ₂ , HBr, and NF ₃ . The content of the halogen element in the inert gas or water vapor is 0.001 to 10% by volume, preferably 0.005 to 10% by volume, more preferably 0.02 to 10% by volume, based on the form of the molecule or the compound. %. For example, when hydrogen chloride gas is used, the content of hydrogen chloride gas in an inert gas or water vapor is preferably 0.02 to 10% by volume.

In the method for forming a silicon oxide film according to the present invention, the desired temperature in the step (c) is from 600 to 12
It is desirably 00 ° C, preferably 700 to 1000 ° C, and more preferably 750 to 900 ° C.

Here, the silicon layer means not only a substrate itself such as a silicon semiconductor substrate, but also an epitaxial silicon layer formed on various substrates such as a silicon semiconductor substrate, a semi-insulating substrate or an insulating substrate, and polycrystalline silicon. A layer or an amorphous silicon layer, a silicon layer in an SOI structure manufactured based on a so-called bonding method or a SIMOX method, and further, a substrate or a component in which a semiconductor element or a component of a semiconductor element is formed on these layers, It means a silicon layer (base) on which a silicon oxide film is to be formed. The method of manufacturing the silicon semiconductor substrate includes the CZ method, the MCZ method, and the D method.
Any method such as LCZ method and FZ method may be used,
Alternatively, a crystal defect may be removed by performing a high-temperature hydrogen annealing treatment in advance.

In order to further improve the characteristics of the formed silicon oxide film, although not essential, in the method for forming a silicon oxide film of the present invention, after the step (c), the formed silicon oxide film is subjected to a heat treatment. Is preferably applied. FIG.
FIG. 16 shows the gas introduction sequence when the step of performing this heat treatment is added to the gas introduction sequence shown in FIG.
However, a step of subjecting the gas introduction sequence shown in FIGS. 1 to 15 to a heat treatment may be added.

In this case, it is desirable that the atmosphere for the heat treatment be an inert gas atmosphere containing a halogen element.
By subjecting the silicon oxide film to a heat treatment in an inert gas atmosphere containing a halogen element, a silicon oxide film having excellent time-zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained. In addition, examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable. As the form of the halogen element contained in the inert gas, for example, hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , C ₂
l _2, HBr, mention may be made of the NF _3. The content of the halogen element in the inert gas is 0.001 to 10% by volume, preferably 0.1 to 10% by volume, based on the form of the molecule or the compound.
005 to 10% by volume, more preferably 0.02 to 10% by volume. For example, when using hydrogen chloride gas, the content of hydrogen chloride gas in the inert gas is preferably 0.02 to 10% by volume.

The heat treatment may be performed in a state where the atmosphere of an inert gas containing a halogen element is reduced in pressure from the atmospheric pressure. The pressure during the heat treatment is 1.3 × 10 ⁴ Pa (100 T
orr). The lower limit of the pressure depends on the apparatus for heat-treating the silicon oxide film, but is preferably as low as possible.

The heat treatment is preferably a furnace annealing treatment. The temperature of the heat treatment is 700-1200 ° C., preferably 700-1000 ° C., and more preferably 700-9.
50 ° C. The heat treatment time is 5 to 60 minutes,
Preferably it is 10 to 40 minutes, more preferably 20 to 30 minutes. As an inert gas in the heat treatment, nitrogen gas,
Examples thereof include an argon gas and a helium gas.

After the heat treatment, the silicon oxide film may be nitrided. In this case, the nitriding treatment is performed with N ₂ O gas, NO
It is desirable to carry out in an atmosphere of gas and NO ₂ gas, and it is particularly desirable to carry out in an atmosphere of N ₂ O gas. Alternatively, it is preferable to perform the nitriding treatment in an atmosphere of NH ₃ gas, N ₂ H ₄ , and hydrazine derivative, and then perform the annealing treatment in an atmosphere of N ₂ O gas and O ₂ . 700 nitriding
It is preferable that the heating is performed at a temperature of from 1200 to 1200 ° C., preferably from 800 to 1150 ° C., more preferably from 900 to 1100 ° C. In this case, it is preferable that the silicon semiconductor substrate be heated by infrared irradiation and furnace annealing.

Alternatively, the atmosphere for the heat treatment may be a nitrogen-based gas atmosphere. Here, as nitrogen-based gas,
Examples include N ₂ , NH ₃ , N ₂ O, and NO ₂ .

In the method of forming a silicon oxide film according to the present invention, the temperature of the atmosphere when heat-treating the formed silicon oxide film is set higher than the temperature of the atmosphere when forming the silicon oxide film in step (c). It can be in the form. In this case, after the formation of the silicon oxide film in the step (c) is completed, the atmosphere may be switched to an inert gas atmosphere, and then the temperature may be increased to an ambient temperature for performing a heat treatment, but the atmosphere contains a halogen element. After switching to the inert gas atmosphere, it is preferable to raise the temperature to the ambient temperature for performing the heat treatment. Here, as the form of the halogen element contained in the inert gas, for example, hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , HBr, N
F ₃ can be mentioned. The content of the halogen element in the inert gas is based on the form of the molecule or compound,
0.001 to 10% by volume, preferably 0.005 to 10%
%, More preferably 0.02 to 10% by volume.
For example, when using hydrogen chloride gas, the content of hydrogen chloride gas in the inert gas is preferably 0.02 to 10% by volume.

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

In the step (a), at least after the start of the supply of oxygen gas to the combustion chamber, until the steam is generated in the combustion chamber by the supply of hydrogen gas to the combustion chamber and supplied to the processing chamber, Supply inert gas to the room. At this time, the temperature in the processing chamber in an inert gas atmosphere is preferably as low as possible in order to suppress the formation of a dry oxide film. However, in such a state, there is a possibility that water vapor generated in the combustion chamber may form dew before reaching the processing chamber. Therefore, the oxide film forming apparatus according to the present invention comprises: (A) a combustion chamber that generates steam by burning hydrogen gas with oxygen gas; and (B) a combustion chamber that communicates with the combustion chamber. An oxide film forming apparatus comprising: a processing chamber for forming a silicon oxide film on the surface of a silicon layer; and (C) a pipe connecting the combustion chamber and the processing chamber, wherein the pipe has an inert gas introduction unit. It is characterized by being provided. It is preferable that the piping including the inert gas introduction unit is provided with a heating unit for preventing the water vapor generated in the combustion chamber from forming dew before reaching the processing chamber. Thereby, it is possible to reliably prevent the water vapor generated in the combustion chamber from forming dew before reaching the processing chamber. In this case, it is preferable to heat the piping including the inert gas introduction part to a temperature exceeding 100 ° C. by the heating means. In addition, it is desirable that the pipe be provided with an inert gas introduction part so that the inert gas flowing into the pipe from the inert gas introduction part provided in the pipe does not flow into the combustion chamber.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

(Example 1) FIG. 17 shows an outline of an oxide film forming apparatus suitable for carrying out the method for forming a silicon oxide film of Example 1.
Shown in This oxide film forming apparatus basically has the same structure as the conventional vertical type oxide film forming apparatus shown in FIG. The points different from the conventional vertical type oxide film forming apparatus are as follows. That is, the combustion chamber 30 and the processing chamber 10
An inert gas introduction part 34 is provided in the pipe 33 connecting the pipe and the pipe 35 for introducing an inert gas (nitrogen gas in the first embodiment) into the inert gas introduction part 34.
Is attached. Further, the pipe 33 including the inert gas introduction part 34 is provided with a heater 36 as a heating means for preventing the water vapor generated in the combustion chamber 30 from forming dew before reaching the processing chamber 10. I have. In addition, the inert gas introduction part 34 provided in the pipe 33
It is desirable that the pipe 33 be provided with an inert gas introduction part 34 so that the inert gas flowing into the combustion chamber 30 does not flow into the combustion chamber 30. Specifically, the direction of the flow of the inert gas flowing through the pipe 35 in the inert gas introduction unit 34 and the direction of the flow of the gas flowing from the combustion chamber 30 in the inert gas introduction unit 34 are acute angles. It is preferable that they intersect with each other.

In the method of forming the silicon oxide film of Example 1, the gas introduction sequence shown in FIG. 18 was employed. (A) In the step (a), after the supply of oxygen gas to the combustion chamber is started, the processing is performed until steam is generated in the combustion chamber by the supply of hydrogen gas to the combustion chamber and supplied to the processing chamber. Supply inert gas to the room. (B) In step (a), after forming a silicon oxide film on the surface of the silicon layer, the supply of hydrogen gas to the combustion chamber is stopped. Then, an inert gas is supplied into the processing chamber while supplying oxygen gas to the combustion chamber for a predetermined time. Example 1
In, the supply of the inert gas into the processing chamber is continued thereafter. (C) In step (c), before the formation of a silicon oxide film with water vapor, after the supply of oxygen gas to the combustion chamber is started, the supply of hydrogen gas to the combustion chamber generates water vapor in the combustion chamber, and the processing is performed. Until the gas is supplied to the chamber, the inert gas is continuously supplied into the processing chamber. (D) In step (c), after forming a silicon oxide film on the surface of the silicon layer, the supply of hydrogen gas to the combustion chamber is stopped. Then, the inert gas is continuously supplied to the processing chamber while the oxygen gas is supplied to the combustion chamber for a predetermined time.

In Example 1, the water vapor was diluted with an inert gas in the second silicon oxide film forming step.

Further, in the method for forming a silicon oxide film of Example 1, after the step (c), the formed silicon oxide film was subjected to a heat treatment. The heat treatment was a heat treatment (furnace annealing) in an inert gas atmosphere containing a halogen element (a nitrogen gas atmosphere containing hydrogen chloride). Also, the first
In the second silicon oxide film forming step, the silicon oxide film was formed only with water vapor. Furthermore, the process (b)
Is an inert gas atmosphere (nitrogen gas atmosphere). In Example 1, the silicon layer was formed from a silicon semiconductor substrate. The formed silicon oxide film functions as a gate oxide film. Less than,
With reference to FIGS. 19 to 26, a method for forming the silicon oxide film of the first embodiment will be described.

[Step-100] First, an N-type single crystal silicon semiconductor substrate (hereinafter simply referred to as a silicon semiconductor substrate)
At 40, an element isolation region 41 having a LOCOS structure is formed by a known method, and well ion implantation, channel stop ion implantation, and threshold adjustment ion implantation are performed. Note that the element isolation region may have a trench structure. Then, R
The fine particles and metal impurities on the surface of the silicon semiconductor substrate 40 are removed by CA cleaning, and then the surface of the silicon semiconductor substrate 40 is cleaned by immersion in a 0.1% aqueous hydrofluoric acid solution for 1 minute. After the surface of the silicon semiconductor substrate 40 is exposed and washed with pure water, the silicon semiconductor substrate 40 is dried by a known IPA drying method (see FIG. 19A). Most of the surface of the silicon semiconductor substrate is terminated with hydrogen, and a very small portion is terminated with fluorine.

[Step-110] Next, the silicon semiconductor substrate 40 is loaded into the substrate loading / unloading section 20 of the oxide film forming apparatus shown in FIG. 17 through a door (not shown) and placed on the quartz boat 24 (FIG. 17). 20 (A)). A nitrogen gas at room temperature is introduced into the processing chamber 10 at a flow rate of 10 SLM through the pipe 31, the combustion chamber 30, the pipe 33, the gas flow path 11, and the gas introduction unit 12, and the inside of the processing chamber 10 is supplied with nitrogen gas at room temperature. Keep the atmosphere. In this state, the shutter 15 is kept closed.

[Step-120] Then, the substrate loading / unloading section 2
0, the door (not shown) is closed, and the gas introduction unit 21 is inserted into the substrate carry-in / out unit 20.
, And exhausted from the gas exhaust unit 22 to make the inside of the substrate loading / unloading unit 20 a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere. Thereafter, the shutter 15 is opened (see FIG. 20B), and the elevator mechanism 23 is operated to operate the quartz boat 24.
Is raised at a rising speed of 500 mm / min, and the silicon semiconductor substrate 40 is carried into the processing chamber 10 having a double-tube structure made of quartz (see FIG. 21A). When the elevator mechanism 23 reaches the highest position, the base of the quartz boat 24 stops communication between the processing chamber 10 and the substrate loading / unloading section 20. The processing chamber 10 includes a pipe 31, a combustion chamber 30, a pipe 3
3. Processing chamber 1 via gas flow path 11 and gas introduction unit 12
Continue to flow nitrogen gas to zero. Next, the heater 15 is operated to set the ambient temperature in the processing chamber 10 to 350 ° C. (see FIG. 21B). The heating rate was 20 ° C./min. On the other hand, the combustion chamber 30 is heated by a heater (not shown), and the temperature of the combustion chamber 30 is set to 750 ° C. Also,
The temperature in the pipe 33 is raised by the heater 36,
0 ° C.

[Step-130] When the atmospheric temperature in the processing chamber 10 is stabilized at 350 ° C., the supply of the nitrogen gas from the pipe 31 is stopped, and the inert gas from the pipe 35 (in the first embodiment, Is nitrogen gas) (flow rate: 10SL)
M) is started. At the same time, the combustion chamber 3
The supply of oxygen gas (flow rate: 5 SLM) to 0 is started (see FIG. 22A). As described above, the temperature at which silicon atoms do not desorb from the surface of the silicon layer (the silicon semiconductor substrate 40 in the first embodiment) (3 in the first embodiment).
A substrate having a silicon layer in the processing chamber 10 in an inert gas atmosphere maintained at 50 ° C. (silicon semiconductor substrate 40)
After the supply of oxygen gas to the combustion chamber 30 is started,
By supplying hydrogen gas to the combustion chamber 10, steam is generated in the combustion chamber 3.
Until it is produced within 0 and fed to the processing chamber 10.
Since the inert gas (nitrogen gas in the first embodiment) is supplied into the processing chamber 10, the silicon oxide film is formed by the water vapor on the silicon layer (the silicon semiconductor substrate 4 in the first embodiment).
Before being formed in 0), the concentration of oxygen gas in contact with the silicon layer can be sufficiently reduced. As a result, formation of a silicon oxide film (formation of a dry oxide film) due to oxygen gas can be suppressed. Further, since the silicon semiconductor substrate 40 is maintained at 350 ° C., it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate 40. Furthermore, since the silicon oxide film is formed on the surface of the silicon semiconductor substrate 40 with hydrogen terminated, the flatness of the interface between the silicon oxide film and the silicon semiconductor substrate 40 is maintained at the atomic level.

[Step-131] From the pipe 32 to the combustion chamber 30
After one minute has passed since the supply of oxygen gas to
Hydrogen gas (flow rate: 2.5 SLM) is introduced into the combustion chamber 30 from the pipe 31. When the combustion of the hydrogen gas is confirmed by a flame detector or the like disposed in the combustion chamber 30, the supply of the nitrogen gas from the pipe 35 is stopped. Thus, in a state where the atmosphere is maintained at a temperature at which silicon atoms do not desorb from the surface of the silicon layer, specifically, in the first embodiment, the processing chamber 1
While maintaining the atmospheric temperature of 0 ° C. at 350 ° C., a silicon oxide film is formed on the surface of the silicon layer (the silicon semiconductor substrate 40 in the first embodiment) by the steam supplied from the combustion chamber 30 (FIG. 22). (B)). In Example 1, a 1.2 nm silicon oxide film was formed on the surface of the silicon semiconductor substrate 40 in the first silicon oxide film forming step. The thickness of this silicon oxide film is a thickness corresponding to ₂ to 3 molecular layers of SiO ₂ , and is sufficient to function as a protective film even in consideration of steps on the surface of the silicon semiconductor substrate. .

[Step-132] After the silicon oxide film is formed on the surface of the silicon layer, the supply of hydrogen gas to the combustion chamber 30 is stopped. Then, while supplying oxygen gas from the pipe 32 to the combustion chamber 30 for a predetermined time, an inert gas (nitrogen gas in the first embodiment) is supplied from the pipe 35 into the processing chamber 10 (FIG. 23A). reference). The supply amount of oxygen gas to the combustion chamber 30 was 5 SLM, and the supply amount of nitrogen gas from the pipe 35 to the processing chamber 10 was 10 SLM. This state was maintained for one minute, and the hydrogen gas remaining in the combustion chamber 30 and the pipe 33 was exhausted while burning. Thereafter, the supply of the nitrogen gas from the pipe 35 is stopped, and the supply of the inert gas (nitrogen gas in the first embodiment) from the pipe 31 to the processing chamber 10 via the combustion chamber 30 and the pipe 33 (flow rate: 10 SLM) )I do.

[Step-140] After that, while continuously supplying an inert gas (nitrogen gas) from the gas introducing section 12 into the processing chamber 10, the atmosphere temperature in the processing chamber 10 of the oxide film forming apparatus is reduced by a soaking tube. The temperature is raised to a desired temperature (800 ° C. in the first embodiment) by the heater 15 via the heater 14 (see FIG. 23B). The heating rate was 10 ° C./min. Since a silicon oxide film which also functions as a protective film has already been formed on the surface of the silicon layer in [Step-131], the silicon layer (silicon semiconductor) is used in [Step-140] (temperature increasing step). Roughness does not occur on the surface of the substrate 40).

[Step-150] Next, while maintaining the atmosphere at a desired temperature (800 ° C. in the first embodiment), a silicon oxide film is further formed by water vapor supplied from the combustion chamber 30. I do. Specifically, the supply of nitrogen gas from the pipe 31 is stopped, and the supply of an inert gas (nitrogen gas in Example 1) from the pipe 35 (flow rate: 10 S
LM). At the same time, the supply of oxygen gas (flow rate: 5 SLM) from the pipe 32 to the combustion chamber 30 is started (see FIG. 24A). As described above, after the supply of oxygen gas to the combustion chamber 30 is started, the processing is performed until steam is generated in the combustion chamber 30 by the supply of hydrogen gas to the combustion chamber 10 and supplied to the processing chamber 10. Since the inert gas is supplied into the chamber 10, the formation of a so-called dry oxide film can be reliably prevented.

[Step-151] From the pipe 32 to the combustion chamber 30
After one minute has passed since the supply of oxygen gas to
Hydrogen gas (flow rate: 2.5 SLM) is introduced into the combustion chamber 30 from the pipe 31. In Example 1, the supply of nitrogen gas (flow rate: 5 SLM) from the pipe 35 was continued even after the combustion of hydrogen gas was confirmed by a flame detector or the like disposed in the combustion chamber 30. Thus, a silicon oxide film is further formed on the surface of the silicon layer (the silicon semiconductor substrate 40 in the first embodiment) by the water vapor supplied from the combustion chamber 30 (see FIG. 24B). In Example 1, a silicon oxide film having a total thickness of 4.0 nm was formed.

[Step-152] After forming the silicon oxide film on the surface of the silicon layer, the supply of hydrogen gas to the combustion chamber 30 is stopped. Then, while supplying oxygen gas to the combustion chamber 30 for a predetermined time, an inert gas (nitrogen gas in Example 1) is supplied from the pipe 35 into the processing chamber 10 (see FIG. 25A). The supply amount of oxygen gas to the combustion chamber 30 was 5 SLM, and the supply amount of nitrogen gas from the pipe 35 to the processing chamber 10 was 10 SLM. This state was maintained for one minute, and the hydrogen gas remaining in the combustion chamber 30 and the pipe 33 was exhausted while burning. Thereafter, the supply of the nitrogen gas from the pipe 35 is stopped, and the supply of the inert gas (nitrogen gas in the first embodiment) from the pipe 31 to the combustion chamber 30 (flow rate: 10 SL)
M).

[Step-160] Then, the ambient temperature of the processing chamber 10 is raised to 850 ° C. by the heater 15 (see FIG. 25B). Thereafter, a nitrogen gas containing 0.1% by volume of hydrogen chloride is supplied from the gas introduction unit 12 to the processing chamber 10.
And heat-treated for 30 minutes (see FIG. 26).

[Step-170] With the above, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 is completed (see FIG. 19B). Thereafter, the processing room 10
The interior is set to a nitrogen gas atmosphere, the elevator mechanism 23 is operated to lower the quartz boat 24, and then the silicon semiconductor substrate 40 is unloaded from the substrate loading / unloading section 20.

[Step-180] In the first embodiment, using the silicon semiconductor substrate on which the silicon oxide film is formed as described above, the silicon oxide film 4 is formed by using a known CVD technique, photolithography technique and dry etching technique.
A gate electrode 43 made of phosphorus-doped polysilicon was formed on the substrate 2 to produce a MOS capacitor (see FIG. 19C).

Comparative Example 1 In Comparative Example 1, a 4.0 nm thick silicon oxide film was formed on the surface of a silicon semiconductor substrate based on a conventional method for forming a silicon oxide film. That is, based on [Step-10] to [Step-40],
A silicon oxide film was formed. In [Step-20], before opening the shutter 15, a nitrogen gas containing 0.5% by volume of oxygen gas is introduced into the processing chamber 10 from the gas introduction unit 12, and the inside of the processing chamber 10 is set at 0.1%. A nitrogen gas atmosphere (atmospheric temperature: 800 ° C.) containing 5% by volume of oxygen gas was used. The temperature in the processing chamber 10 was set to 800 ° C., and a silicon oxide film was formed on the surface of the silicon semiconductor substrate by a pyrogenic oxidation method. A MOS capacitor was manufactured from the silicon semiconductor substrate on which the silicon oxide film was formed in the same manner as in Example 1. Before the silicon oxide film was formed on the surface of the silicon semiconductor substrate by the pyrogenic oxidation method, the silicon semiconductor substrate was loaded into the processing chamber 10 in a nitrogen gas atmosphere containing 0.5% by volume of oxygen gas. And a thickness of 2.3 on the surface of the silicon semiconductor substrate.
nm of a dry oxide film was formed.

The M prepared according to Example 1 and Comparative Example 1
In order to evaluate the long-term reliability of the silicon oxide film for OS capacitors, time-dependent dielectric breakdown (Time Dependent Die
Electric breakdown (TDDB) characteristics were measured.
This aging dielectric breakdown is a phenomenon in which a dielectric breakdown does not occur at the moment when a current stress or a voltage stress is applied, but the dielectric breakdown occurs in a silicon oxide film after a certain time has elapsed after the application of the stress.

The time-dependent dielectric breakdown (TDDB) characteristic was evaluated by the following method. Fifty MOS capacitors were formed on one silicon semiconductor substrate 40. The gate area of the MOS capacitor was set to 0.1 mm ² . Then, two silicon semiconductor substrates were used for the evaluation. A circuit schematically shown in FIG. 27 is made, and a constant current (J
= 0.1 A / cm ² ) A so-called Coulomb breakdown (Q _BD ) was measured by a constant current stress method applying a stress. Here, Q _BD is represented by the product of J (A / cm ² ) and the time t _BD until dielectric breakdown. Then, a charge amount corresponding to a cumulative failure rate of 50% in the Weibull probability distribution of Q _BD was obtained. The results were as shown in Table 1 below.
As a result of the test, the reliability of the silicon oxide film manufactured in Example 1 was 4 to 5 times higher than that of Comparative Example 1.

Example 2 In Example 2, an N-type silicon epitaxial layer formed on a P-type single-crystal silicon semiconductor substrate was used as a silicon layer. Except for this point, a silicon oxide film was formed on the surface of the N-type silicon epitaxial layer in the same manner as in Example 1. However, in [Step-110] of Example 1, the pipe 31,
Combustion chamber 30, pipe 33, gas flow path 11, and gas introduction section 1
2, nitrogen gas is introduced into the processing chamber 10 at a flow rate of 10 SLM.
0 ° C. Further, in [Step-120] of the first embodiment, the elevator mechanism 23 is operated to operate the quartz boat 24.
Was raised at a rate of 250 mm / min, and the silicon semiconductor substrate 40 was carried into the processing chamber 10 having a double-tube structure made of quartz. At this time, the atmospheric temperature of the processing chamber 10 is set to 350 ° C.
And

In the second embodiment as well, the M
An OS capacitor was manufactured, and TDDB characteristics were measured in order to evaluate the long-term reliability of the silicon oxide film. Table 1 shows the results. As a result of the test, the reliability of the silicon oxide film manufactured in Example 2 was higher than that of Example 1.

[0069]

Table 1 Example 1 45-48 C / cm ² Example 2 56-58 C / cm ² Comparative Example 1 10-11 C / cm ²

(Embodiment 3) In Embodiment 3, FIG.
Was adopted. That is, Example 3 differs from Example 1 in that [Step-1 of Example 1]
20] and [Step-130]. Hereinafter, steps in which the third embodiment is different from the first embodiment will be described.

In Example 3, [Step-
110], the silicon semiconductor substrate 40 is
Is carried into the substrate carrying-in / out section 20 of the oxide film forming apparatus shown in FIG. The room temperature nitrogen gas is supplied to the processing chamber 10 via the pipe 31, the combustion chamber 30, the pipe 33, the gas flow path 11, and the gas introduction unit 12 for 10 seconds.
It is introduced at a flow rate of LM, and the inside of the processing chamber 10 is kept in a nitrogen gas atmosphere at room temperature. In this state, the shutter 1
5 is closed.

After the loading of the silicon semiconductor substrate 40 into the substrate loading / unloading section 20 is completed, a door (not shown) is closed, nitrogen gas is introduced into the substrate loading / unloading section 20 from the gas introduction section 21, and the gas exhaust section 22 is opened. From the substrate loading / unloading section 20
The inside is a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and the oxygen gas
If it becomes 0 ppm or less, it is determined that the inside of the substrate carry-in / out section 20 has been sufficiently brought into the nitrogen gas atmosphere. Thereafter, the shutter 15 is opened, the elevator mechanism 23 is operated, and the quartz boat 24 is raised at a rising speed of 500 mm / min.
The silicon semiconductor substrate 40 is carried into the processing chamber 10 having a double tube structure made of quartz. In the processing chamber 10, the nitrogen gas continues to flow into the processing chamber 10 via the pipe 31, the combustion chamber 30, the pipe 33, the gas flow path 11, and the gas introduction unit 12. Next, the heater 15 is operated to reduce the atmospheric temperature in the processing chamber 10 to 12
0 ° C. The heating rate was 20 ° C./min. On the other hand, the combustion chamber 30 is heated by a heater (not shown), and the temperature of the combustion chamber 30 is set to 750 ° C. Also, the heater 36
Thereby, the temperature in the pipe 33 is set to 120 ° C.

Next, in the same step as [Step-130] of the first embodiment, when the atmospheric temperature in the processing chamber 10 is stabilized at 120 ° C., the supply of the nitrogen gas from the pipe 31 is stopped. Then, the supply of inert gas (nitrogen gas in the third embodiment) from the pipe 35 (flow rate: 10 SLM) is started. At the same time, supply of oxygen gas (flow rate: 5 SLM) from the pipe 32 to the combustion chamber 30 is started. in this way,
Silicon layer (in the third embodiment, the silicon semiconductor substrate 4
After a substrate having a silicon layer is placed in the processing chamber 10 in an inert gas atmosphere maintained at a temperature at which silicon atoms are not desorbed from the surface (0) (120 ° C. in Example 3), the combustion chamber 30 After the supply of oxygen gas is started, the combustion chamber 10
The supply of hydrogen gas to the processing chamber 10 causes steam to be generated in the combustion chamber 30 and supplied to the processing chamber 10.
An inert gas (nitrogen gas in Example 3) is supplied into the inside. As a result, before the silicon oxide film is formed on the silicon layer (the silicon semiconductor substrate 40 in the third embodiment) by the water vapor, the concentration of the oxygen gas in contact with the silicon layer can be sufficiently reduced. Formation of an oxide film (formation of a dry oxide film) can be suppressed. Further, since the silicon semiconductor substrate 40 is maintained at 120 ° C., it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate 40. Furthermore, since the silicon oxide film is formed on the surface of the silicon semiconductor substrate 40 with hydrogen terminated, the flatness of the interface between the silicon oxide film and the silicon semiconductor substrate 40 is maintained at the atomic level.

After one minute has elapsed from the start of the supply of oxygen gas from the pipe 32 to the combustion chamber 30, hydrogen gas (flow rate: 2.5 SLM) is introduced from the pipe 31 into the combustion chamber 30.
In the third embodiment, the supply of the nitrogen gas from the pipe 35 is continued even after the combustion of the hydrogen gas is confirmed by the flame detector and the like disposed in the combustion chamber 30. Thus, in a state where the atmosphere is maintained at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer, specifically, in Example 3, the atmosphere temperature of the processing chamber 10 is maintained at 120 ° C. The formation of the silicon oxide film on the surface of the silicon layer (the silicon semiconductor substrate 40 in the third embodiment) is started by the water vapor supplied from the combustion chamber 30. Since the pipe 33 is maintained at 120 ° C. by the heater 36,
There is no risk of dew formation in the pipe 33.

Thereafter, the temperature of the atmosphere in the processing chamber 10 was raised to 350 ° C. by the heater 15. Heating rate 2
0 ° C / min. The atmosphere temperature in the processing chamber 10 is 3
Until the temperature reaches 50 ° C., the processing chamber 10 is supplied with water vapor. However, the temperature is low and the water vapor is diluted with nitrogen gas. The silicon oxide film is hardly formed on the surface of the substrate. When the atmospheric temperature in the processing chamber 10 is stabilized at 350 ° C., the supply of the nitrogen gas from the pipe 35 is stopped. Also in the third embodiment, in the first silicon oxide film forming step, 1.
A 2 nm silicon oxide film was formed on the surface of the silicon semiconductor substrate 40.

The subsequent steps of forming the silicon oxide film can be the same as those of [Step-132] to [Step-170] of the first embodiment, and thus detailed description is omitted.

Example 4 In Example 4, first, a silicon oxide film forming step, a temperature raising step, and a second silicon oxide film forming step were performed by using an inert gas, an oxygen gas, The introduction sequence of hydrogen gas was used. That is, in place of [Step-132] and [Step-140] in the first embodiment, an inert gas (nitrogen gas) is not supplied from the gas introduction unit 12 to the processing chamber 10 and the processing gas is introduced into the processing chamber 10. Without stopping the supply of water vapor, the temperature of the atmosphere in the processing chamber 10 of the oxide film forming apparatus is set to a desired temperature (800 in the fourth embodiment) by the heater 15 through the soaking tube 14.
The temperature was raised to ΔC). In the same step as [Step-130], a silicon oxide film having a thickness of 1.0 nm was formed. Further, instead of [Step-150] in Example 1,
An inert gas (nitrogen gas) is supplied from the gas introduction unit 12 to the processing chamber 1.
0, and the supply of steam into the processing chamber 10 was continued. Other steps were the same as in Example 1. Except for the above, in Example 4, a silicon oxide film was formed in the same process as in Example 1.

(Embodiment 5) In Embodiment 5, FIG.
Was used. Also in Example 5, the silicon layer was formed from a silicon semiconductor substrate. The formed silicon oxide film functions as a gate oxide film. In the fifth embodiment, unlike the first embodiment,
Water vapor contains a halogen element (specifically, chlorine). Note that chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in water vapor was set to 0.1% by volume. The atmosphere in the step of raising the ambient temperature to the desired temperature (temperature raising step) was an inert gas atmosphere. After the second silicon oxide film forming step, the formed silicon oxide film is subjected to a heat treatment (furnace annealing) in an inert gas atmosphere containing a halogen element (a nitrogen gas atmosphere containing hydrogen chloride). gave. The method for forming the silicon oxide film according to the fifth embodiment will be described below, but only the points different from the method for forming the silicon oxide film according to the first embodiment will be described. In the method of forming the silicon oxide film of the fifth embodiment, the gas introduction sequence shown in FIG. 18 was employed as in the first embodiment.

In Example 5, [Step-
100] to [Step-130].
In the same step as [Step-131] in the first embodiment, in the fifth embodiment, if one minute has elapsed after the supply of the oxygen gas from the pipe 32 to the combustion chamber 30 starts, the hydrogen gas ( (Flow rate: 2.5 SLM) is introduced into the combustion chamber 30. When the combustion of the hydrogen gas is confirmed by a flame detector or the like disposed in the combustion chamber 30, the supply of the nitrogen gas from the pipe 35 is stopped. Thus, in a state where the atmosphere is maintained at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer, specifically, in the fifth embodiment, the atmosphere temperature of the processing chamber 10 is maintained at 350 ° C. A water vapor supplied from the combustion chamber 30 forms a silicon oxide film on the surface of the silicon layer (the silicon semiconductor substrate 40 in the fifth embodiment). In Example 5, hydrogen chloride was introduced through the pipe 35, and the steam contained 0.1% by volume of hydrogen chloride. In some cases,
Hydrogen chloride can also be introduced through the pipe 32. Specifically, the steam generated in the combustion chamber 30 and the hydrogen chloride gas are supplied to the pipe 33, the gas passage 11, and the gas introduction unit 12.
And a silicon oxide film having a thickness of about 1 nm is formed on the surface of the silicon semiconductor substrate by a pyrogenic oxidation method.

Thereafter, [Step-132] of Example 1 is repeated.
[Step-150] is executed. [Step-140]
In the same step as the (heating step), the surface of the silicon layer (silicon semiconductor substrate) is not roughened.

While the supply of water vapor (which may or may not contain a halogen element) into the processing chamber 10 is continued, the atmospheric temperature in the processing chamber 10 of the oxide film forming apparatus is reduced by the heat equalizing pipe 14. The temperature may be raised to a desired temperature (800 ° C. in the fifth embodiment) by the heater 15 through the heater. In this case, the steps similar to [Step-132] and [Step-150] in Example 1 are omitted, and no inert gas is introduced. That is, an inert gas (nitrogen gas) is not supplied from the gas introduction unit 12 to the processing chamber 10. FIG. 29 shows the gas introduction sequence in this case.

Then, in the same step as [Step-151] of the first embodiment, in the fifth embodiment, if one minute has elapsed after the start of the supply of the oxygen gas from the pipe 32 to the combustion chamber 30, the pipe 31 to hydrogen gas (flow rate: 2.5SL)
M) is introduced into the combustion chamber 30. Even after the combustion of hydrogen gas is confirmed by a flame detector or the like disposed in the combustion chamber 30, the supply of nitrogen gas (flow rate:
5SLM). Thus, a silicon oxide film is further formed on the surface of the silicon layer (the silicon semiconductor substrate 40 in the fifth embodiment) by the water vapor supplied from the combustion chamber 30. In Example 5, a silicon oxide film having a total thickness of 4.0 nm was formed. Note that, in the water vapor, the concentration is 0.
It contains 1% by volume of hydrogen chloride.

Thereafter, by performing the same steps as [Step-160] and [Step-170] of the first embodiment, a silicon oxide film is formed on the silicon layer (the silicon semiconductor substrate also in the fifth embodiment). Can be.

Example 6 In Example 6, a single wafer type oxide film forming apparatus was used. FIG. 30 is a schematic diagram of a horizontal oxide film forming apparatus suitable for implementing the sixth embodiment. This oxide film forming apparatus includes a processing chamber 50 and a resistance heater 51 as heating means for heating the silicon layer. The processing chamber 50 is formed of a quartz furnace tube, and houses a substrate having a silicon layer therein for forming a silicon oxide film on the silicon layer. The resistance heater 51 serving as a heating unit is disposed outside the processing chamber 50, and
It is disposed substantially parallel to the surface of the silicon layer. For example, a silicon semiconductor substrate 40 which is a substrate having a silicon layer
Is placed on a wafer stage 52 and is carried into and out of the processing chamber 50 via a gate valve 53 provided at one end of the processing chamber 50. The oxide film forming apparatus further includes a gas introduction unit 54 for introducing water vapor or the like into the processing chamber 50, and a gas exhaust unit 55 for exhausting gas from the processing chamber 50. The temperature of the substrate can be measured by a thermocouple (not shown).

The combustion chamber 60 is connected via a pipe 61 and a pipe 62.
The hydrogen gas supplied to the combustion chamber 60 is mixed with oxygen gas at a high temperature in the combustion chamber 60 and burned to generate steam. The water vapor is supplied to the pipe 63 and the gas introduction section 54.
Is supplied into the processing chamber 50 via the An inert gas introduction section 64 is provided in a pipe 63 connecting the combustion chamber 60 and the processing chamber 50, and an inert gas (nitrogen gas in the sixth embodiment) is introduced into the inert gas introduction section 64. Piping 65 is attached. Further, the pipe 63 including the inert gas introduction part 64 is provided with a heater 66 as a heating means for preventing the steam generated in the combustion chamber 60 from dew condensation before reaching the processing chamber 50. I have.
From the inert gas introduction part 64 provided in the pipe 63 to the pipe 6
It is desirable that the pipe 63 be provided with an inert gas introduction portion 64 so that the inert gas flowing into the combustion chamber 3 does not flow into the combustion chamber 60 side. Specifically, the direction of the flow of the inert gas flowing through the pipe 65 in the inert gas introduction unit 64 and the direction of the flow of the gas flowing from the combustion chamber 60 in the inert gas introduction unit 64 are acute angles. It is preferable that they meet each other.

Alternatively, a horizontal oxide film forming apparatus of the type schematically shown in FIG. 31 can be used. This figure 3
In the horizontal oxide film forming apparatus shown in FIG. 1, the heating means comprises a plurality of lamps 51A emitting infrared or visible light.
It is composed of The temperature of the substrate is measured by a pyrometer (not shown). Other structures can be basically the same as those of the oxide film forming apparatus shown in FIG. 30, and therefore detailed description is omitted.

The method of forming the silicon oxide film of the sixth embodiment will be described below. In the method of forming the silicon oxide film of the sixth embodiment, the gas introduction sequence shown in FIG. 29 was employed.

[Step-600] First, after a device isolation region and the like are formed in a silicon semiconductor substrate in the same manner as in Example 1, fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate is washed with a 0.1% hydrofluoric acid aqueous solution to expose the surface of the silicon semiconductor substrate 40, and after washing with pure water, the silicon semiconductor substrate 40 is dried by a known IPA drying method. Let it. Most of the surface of the silicon semiconductor substrate is terminated with hydrogen, and a very small portion is terminated with fluorine.

[Step-610] The processing chamber 50 is set in advance through the pipe 61, the combustion chamber 60, the pipe 63, and the gas inlet 54.
A nitrogen gas (flow rate: 5 SLM) at room temperature is introduced into the processing chamber 50, and the inside of the processing chamber 50 is kept in a nitrogen gas atmosphere at room temperature. Then, the silicon semiconductor substrate 40 placed on the wafer table 52 is loaded into the processing chamber 50 by opening the gate valve 53 of the oxide film forming apparatus shown in FIG. 30 or FIG. close.

[Step-620] In the processing chamber 50, the piping 6
1. Nitrogen gas is continuously supplied to the processing chamber 50 via the combustion chamber 60, the pipe 63, and the gas inlet 52. Next, the heater 5
1 is operated to set the ambient temperature in the processing chamber 50 to 350 ° C. On the other hand, the combustion chamber 60 is heated by a heater (not shown).
Is heated to bring the temperature of the combustion chamber 60 to 750 ° C. Further, the temperature in the pipe 63 is increased by the heater 66,
350 ° C.

[Step-630] When the atmospheric temperature in the processing chamber 50 is stabilized at 350 ° C., the supply of the nitrogen gas from the pipe 61 is stopped, and the inert gas from the pipe 65 (in the sixth embodiment). Supply (flow rate: 5 SLM)
To start. At the same time, supply of oxygen gas from the pipe 62 to the combustion chamber 60 (flow rate: 2.5 SLM) is started.
As described above, the inside of the processing chamber 50 in an inert gas atmosphere maintained at a temperature at which silicon atoms do not desorb from the surface of the silicon layer (the silicon semiconductor substrate 40 also in the sixth embodiment) (350 ° C. in the sixth embodiment). After a substrate having a silicon layer (silicon semiconductor substrate 40) is disposed in the combustion chamber 60,
After the supply of oxygen gas to the combustion chamber 60 is started, steam is generated in the combustion chamber 60 by the supply of hydrogen gas to the combustion chamber 60, and the inert gas is introduced into the processing chamber 50 until the steam is supplied to the processing chamber 50. Since nitrogen gas is supplied in Example 6, the concentration of oxygen gas in contact with the silicon layer is sufficiently reduced before the silicon oxide film is formed on the silicon layer (the silicon semiconductor substrate 40 in Example 6) by water vapor. It becomes possible. As a result, formation of a silicon oxide film (formation of a dry oxide film) due to oxygen gas can be suppressed. Further, since the silicon semiconductor substrate 40 is maintained at 350 ° C., it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate 40. Furthermore, since the silicon oxide film is formed on the surface of the silicon semiconductor substrate 40 with hydrogen terminated, the flatness of the interface between the silicon oxide film and the silicon semiconductor substrate 40 is maintained at the atomic level.

[Step-631] From the pipe 62 to the combustion chamber 60
After one minute has passed since the supply of oxygen gas to
Hydrogen gas (flow rate: 2.5 SLM) is introduced into the combustion chamber 60 from the pipe 61. When the combustion of the hydrogen gas is confirmed by a flame detector or the like disposed in the combustion chamber 60, the supply of the nitrogen gas from the pipe 65 is stopped. Thus, in a state where the atmosphere is maintained at a temperature at which silicon atoms do not desorb from the surface of the silicon layer, specifically, in the sixth embodiment, the processing chamber 5
With the atmosphere temperature of 0 maintained at 350 ° C., a silicon oxide film is formed on the surface of the silicon layer (the silicon semiconductor substrate 40 in the sixth embodiment) by the steam supplied from the combustion chamber 60. In Example 6, a 1.2 nm silicon oxide film was formed on the surface of the silicon semiconductor substrate 40 in the first silicon oxide film forming step.

[Step-640] Thereafter, while the supply of steam into the processing chamber 50 is continued, the atmospheric temperature in the processing chamber 50 is raised to a desired temperature (800 ° C. in the sixth embodiment) by the heating means 51. ). In the sixth embodiment, since the heating means is disposed substantially parallel to the surface of the silicon layer, it is possible to suppress the occurrence of in-plane temperature variation of the substrate when the substrate is heated. The in-plane thickness variation of the silicon oxide film formed therein can be effectively suppressed.

[Step-650] After the temperature of the atmosphere in the processing chamber 50 reaches a desired temperature (800 ° C. in the sixth embodiment), the steam is removed while maintaining the atmosphere at the desired temperature. A silicon oxide film is further formed by the used thermal oxidation method. Specifically, the steam generated in the combustion chamber 60 is supplied to the processing chamber 5 through the pipe 63 and the gas introduction unit 54.
The silicon oxide film 42 having a total thickness of 4.0 nm is formed on the surface of the silicon semiconductor substrate 40 by the pyrogenic oxidation method.

[Step-660] After forming a silicon oxide film on the surface of the silicon layer, the supply of hydrogen gas to the combustion chamber 60 is stopped. Then, while supplying the oxygen gas to the combustion chamber 60 for a predetermined time, the inert gas (nitrogen gas in the sixth embodiment) is continuously supplied from the pipe 65 into the processing chamber 50. The supply amount of oxygen gas to the combustion chamber 60 is 2.5 SLM,
The supply amount of nitrogen gas from the pipe 65 to the processing chamber 50 is 5 SL
M. This state was maintained for 1 minute, and exhausted while burning the hydrogen gas remaining in the combustion chamber 60 and the pipe 63.
Then, the supply of the nitrogen gas from the pipe 65 is stopped, and the supply of the inert gas (nitrogen gas in the sixth embodiment) to the combustion chamber 60 from the pipe 61 (flow rate: 5 SLM) is performed.

[Step-670] Then, the ambient temperature of the processing chamber 50 is raised to 850 ° C. by the heater 51. Thereafter, nitrogen gas containing 0.1% by volume of hydrogen chloride was introduced into the processing chamber 50 from the gas introduction unit 54,
Heat treatment is performed.

[Step-680] Thus, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate 40 is completed. Thereafter, the inside of the processing chamber 50 is set to a nitrogen gas atmosphere, the gate valve 53 is opened, and the silicon semiconductor substrate 40 placed on the wafer table 52 is carried out of the processing chamber 50.

The silicon oxide film described in the first to fifth embodiments can be formed using the horizontal oxide film forming apparatus described in the sixth embodiment.

The present invention has been described based on the preferred embodiments, but the present invention is not limited to these embodiments. The various conditions and the structure of the oxide film forming apparatus described in the embodiments are merely examples, and can be changed as appropriate. The introduction sequence of the inert gas, the oxygen gas, and the hydrogen gas in each embodiment is also an example, and can be appropriately changed.

In the [step-140] of the first embodiment or in the temperature raising step of the fifth embodiment, while supplying an inert gas (for example, nitrogen gas) from the gas introducing section 12 into the processing chamber 10, the oxide film forming apparatus The temperature of the atmosphere in the processing chamber 10 was raised to a desired temperature by a heater 15 via a soaking tube 14, but instead, for example, an inert gas containing 0.1% by volume of hydrogen chloride gas (for example, nitrogen gas) ) May be supplied from the gas introduction unit 12 into the processing chamber 10, and the temperature of the atmosphere in the processing chamber 10 of the oxide film forming apparatus may be increased to a desired temperature by the heater 15 via the soaking tube 14. In addition, in [Step-160] of Example 1 and Example 5,
While the temperature of the atmosphere in the processing chamber 10 was raised to 850 ° C. by the heater 15 while introducing an inert gas (for example, nitrogen gas) from the gas introduction unit 12 into the processing chamber 10, for example, hydrogen chloride gas was used instead. An inert gas (for example, nitrogen gas) containing 0.1% by volume is supplied from the gas introduction unit 12 to the processing chamber 1.
0 and the temperature of the atmosphere in the processing chamber 10 is reduced by the heater 1.
5, the temperature may be raised to 850 ° C.

In the embodiment, a silicon oxide film is formed exclusively on the surface of a silicon semiconductor substrate, or a silicon oxide film is formed on an epitaxial silicon layer formed on an insulating layer formed on the substrate. However, a silicon oxide film can be formed on the surface of the polycrystalline silicon layer or the amorphous silicon layer. Alternatively, a silicon oxide film may be formed on the surface of a silicon layer in the SOI structure, or a silicon element may be formed on a substrate on which a semiconductor element or a component of the semiconductor element is formed, or on a surface of a silicon layer formed thereon. An oxide film may be formed. Furthermore, a silicon oxide film may be formed on a surface of a silicon element formed on a substrate on which a semiconductor element or a component of the semiconductor element is formed, or a base insulating layer formed on the substrate. The heat treatment after the formation of the silicon oxide film is not essential and can be omitted in some cases.

FIG. 32 is a schematic sectional view of a vertical oxide film forming apparatus having a slightly different form from the vertical oxide film forming apparatus shown in FIG. The processing chamber 10 of this vertical oxide film forming apparatus includes an upper region 10A and a lower region 10B, and the ambient temperature of the lower region 10B is controlled by a heater 15. On the other hand, outside the upper region 10A, a plurality of lamps 15A that emit infrared light or visible light are arranged. Then, for example, [Step-130] of Example 1
In the same step as [Step-132], a silicon oxide film is formed on the surface of the silicon layer by an oxidation method using water vapor while maintaining an atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer. This silicon oxide film is formed in the lower region 10B of the processing chamber 10. At this time, the ambient temperature in the upper region 10A of the processing chamber 10 is:
The temperature is maintained at 400 ° C. by the lamp 15A. afterwards,
In the same step as [Step-140] of the first embodiment, the supply of water vapor into the processing chamber 10 is stopped, and an inert gas (for example, nitrogen gas) is supplied from the gas introduction unit 12 into the processing chamber 10. Region 1 above the processing chamber 10 of the oxide film forming apparatus
The ambient temperature of 0A is raised to a desired temperature by the lamp 15A, then the elevator mechanism 23 is operated to raise the quartz boat 24, and the silicon semiconductor substrate 40 is moved to the upper region 10A of the processing chamber 10. And Example 1
In steps similar to [Step-150] to [Step-152], a silicon oxide film 42 is formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method. Next, in the same step as [Step-160] in Example 1, the supply of steam was stopped, and an inert gas (for example, nitrogen gas) was introduced into the processing chamber 10 from the gas introduction unit 12.
The ambient temperature of the upper region 10A of the processing chamber
The temperature is raised to 850 ° C. by A. Thereafter, an inert gas containing 0.1% by volume of hydrogen chloride (for example, nitrogen gas)
Is introduced into the processing chamber 10 from the gas inlet 12 and the processing chamber 1
In the upper region 10A, the heat treatment is performed for 30 minutes.

Alternatively, FIG. 33 is a schematic cross-sectional view of a horizontal silicon oxide film forming apparatus slightly different from the horizontal silicon oxide film forming apparatus shown in FIG. The processing chamber 50 of this horizontal silicon oxide film forming apparatus includes a first region 50A and a second region 50B, and the ambient temperature of each of the first region 50A and the second region 50B is the lamp 151A and the second region 50B. It is controlled by the lamp 151B. Then, for example, in the same step as [Step-631] in Example 6, the surface of the silicon layer is oxidized using water vapor while maintaining the atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer. A silicon oxide film is formed in the processing chamber 5.
0 in the first area 50A. The first area 50A
Is controlled by the lamp 151A. At this time, the ambient temperature in the second region 50B of the processing chamber 50 is maintained at 350 ° C. by the lamp 151B. Thereafter, in the same step as [Step-640] of the sixth embodiment, while the supply of steam into the processing chamber 50 is continued, the atmospheric temperature of the second region 50B of the processing chamber 50 is reduced.
The temperature is raised to a desired temperature by the lamp 151B, and the substrate is moved to the second area 50B. After that, in the same step as [Step-650], while keeping the ambient temperature of the second region 50B of the processing chamber 50 at a desired temperature by the lamp 151B, the silicon is further oxidized by steam using an oxidation method. An oxide film is formed. Thereafter, in the same step as [Step-660], the supply of steam is stopped, and an inert gas (for example, nitrogen gas) is introduced into the processing chamber 50 from the gas introduction unit 54, and the second gas in the processing chamber 50 is discharged. The ambient temperature in the region 50B is raised to 850 ° C. by the lamp 151B. Thereafter, an inert gas (for example, nitrogen gas) containing 0.1% by volume of hydrogen chloride is supplied from the gas introduction unit 54 to the processing chamber 50.
And heat-treated for 5 minutes. Note that instead of the lamp in the silicon oxide film forming apparatus of FIG.
As described above, a resistance heater can be used.

Table 2 shows a step of forming a silicon oxide film on the surface of the silicon layer by an oxidation method using water vapor while maintaining an atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer (Table 2). In the first oxidation step), the atmosphere in the step of raising the ambient temperature to the desired temperature (in Table 2, referred to as the first temperature raising step), and the state where the atmosphere is maintained at the desired temperature. At
The atmosphere in the step of forming a silicon oxide film by the oxidation method using water vapor (indicated as a second oxidation step in Table 2) and the atmosphere for performing heat treatment on the formed silicon oxide film are heated. (Step 2 in Table 2)
(Indicated as a temperature raising step). In Table 2, the steam atmosphere is described as “steam”, the steam atmosphere containing a halogen element is described as “* steam”, the inert gas atmosphere is described as “inert gas”, and the halogen element is contained. Inert gas atmosphere "* inert gas". Here, the combinations of various atmospheres shown in Table 2 are shown in FIGS.
1. It can be realized by the oxide film forming apparatus shown in FIG.

[0105]

[Table 2] First oxidation step First heating step Second oxidation step Second heating step Water vapor inert gas water vapor inert gas water vapor inert gas water vapor * inert gas water vapor inert gas * water vapor non Active gas steam inert gas * steam * inert gas steam * inert gas steam inert gas steam * inert gas steam * inert gas steam * inert gas * steam inert gas steam * inert gas * steam * un Inactive gas steam Vapor steam Inert gas steam Vapor steam * Inert gas steam Vapor * Steam Inert gas steam Vapor * Steam * Inert gas steam * Steam Steam Inert gas steam * Steam * Inert gas steam * Steam * Steam Inert gas steam * steam * steam * inert gas * steam inert gas steam non Inert gas * water vapor inert gas * water vapor inert gas * water vapor inert gas * water vapor inert gas * water vapor inert gas * water vapor * inert gas * water vapor * inert gas water vapor inert gas * water vapor * inert gas water vapor * Inert gas * Steam * Inert gas * Steam Inert gas * Steam * Inert gas * Steam * Inert gas * Steam steam steam Inert gas * Steam steam steam * Inert gas * Steam steam * Steam inert gas * Steam * Steam * Inert gas * Steam * Steam * Inert gas * Steam * Steam * Inert gas * Steam * Steam * Steam inert gas * Steam * Steam * Steam * Inert gas

[0106]

According to the method for forming a silicon oxide film of the present invention, the concentration of oxygen gas in contact with the silicon layer can be sufficiently reduced before the silicon oxide film is formed by water vapor. It is possible to suppress the formation of an oxide film (the formation of a dry oxide film). In addition, a silicon oxide film is formed on the surface of the silicon layer by an oxidation method using water vapor while maintaining an atmosphere at a temperature at which silicon atoms do not desorb from the surface of the silicon layer. As a result, the silicon oxide film finally formed does not include a dry oxide film having low reliability, and can not only form a silicon oxide film having excellent characteristics, but also provide an uneven surface on the silicon layer. (Roughness) can be prevented. Therefore, a decrease in channel mobility can be prevented, the drive current of the MOS transistor element is hardly deteriorated, and the occurrence of a stress leak phenomenon that causes deterioration of data retention characteristics in a flash memory or the like can be suppressed.

Further, in a state where a silicon oxide film which also functions as a protective film has already been formed on the surface of the silicon layer, the ambient temperature is raised to a desired temperature, and further, by an oxidation method using water vapor. Since a silicon oxide film is formed, the surface of the silicon layer becomes uneven (rough) during the temperature raising process.
Does not occur, and a silicon oxide film having excellent characteristics can be formed. As a result, it is possible to form an extremely thin gate oxide film having excellent long-term reliability. Further, in the method for forming a silicon oxide film of the present invention, since the silicon oxide film is formed by an oxidation method using water vapor, a silicon oxide film having excellent time-dependent dielectric breakdown (TDDB) characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in a method for forming a silicon oxide film of the present invention.

FIG. 2 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 3 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 4 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 5 is a view schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 6 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 7 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 8 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 9 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 10 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 11 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 12 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 13 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 14 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 15 is a view schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 16 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 17 is a schematic view of an oxide film forming apparatus suitable for performing the method of forming a silicon oxide film in Example 1.

FIG. 18 is a diagram schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 19 is a schematic partial cross-sectional view of a silicon semiconductor substrate and the like for describing a method for forming a silicon oxide film of the present invention.

FIG. 20 is a schematic cross-sectional view of an oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1.

FIG. 21 is a schematic cross-sectional view of an oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1, following FIG. 20;

FIG. 22 is a schematic cross-sectional view of an oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1, following FIG. 21;

FIG. 23 is a schematic cross-sectional view of an oxide film forming apparatus and the like for explaining a method of forming a silicon oxide film in Example 1, following FIG. 22;

FIG. 24 is a schematic cross-sectional view of an oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1, following FIG. 23;

FIG. 25 is a schematic cross-sectional view of an oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1, following FIG. 24;

FIG. 26 is a schematic cross-sectional view of an oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1, following FIG. 25;

FIG. 27 is a schematic diagram of a circuit for measuring a time-dependent dielectric breakdown (TDDB) characteristic.

FIG. 28 is a view schematically showing a sequence of introducing an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the third embodiment.

FIG. 29 is a diagram schematically showing an introduction sequence of an inert gas, an oxygen gas, and a hydrogen gas in the method for forming a silicon oxide film of the present invention.

FIG. 30 is a schematic sectional view of a horizontal oxide film forming apparatus suitable for carrying out a method for forming a silicon oxide film according to a second embodiment of the present invention.

FIG. 31 is a second embodiment of the present invention, which is slightly different in structure from FIG. 30;
FIG. 4 is a schematic cross-sectional view of a horizontal oxide film forming apparatus suitable for carrying out a method of forming a silicon oxide film according to an embodiment.

32 is a schematic cross-sectional view of a vertical oxide film forming apparatus having a slightly different form from the vertical oxide film forming apparatus shown in FIG.

FIG. 33 is a schematic sectional view of a horizontal silicon oxide film forming apparatus having a slightly different type from the horizontal silicon oxide film forming apparatus shown in FIG. 31;

FIG. 34 is a conceptual view of a conventional vertical type oxide film forming apparatus.

FIG. 35 is a conceptual diagram for explaining a method of forming a silicon oxide film on a silicon semiconductor substrate using the conventional vertical oxide film forming apparatus shown in FIG.

FIG. 36 is a conceptual diagram for explaining a method of forming a silicon oxide film on a silicon semiconductor substrate, following FIG. 35;

FIG. 37 is a conceptual diagram for explaining a method of forming a silicon oxide film on a silicon semiconductor substrate, following FIG. 36;

FIG. 38 is a conceptual diagram for explaining a method of forming a silicon oxide film on a silicon semiconductor substrate, following FIG. 37;

[Explanation of symbols]

10, 50 processing chamber, 11 gas flow path, 12
..Gas inlet, 13 ... Gas exhaust, 14 ... Heat equalizer, 15 ... Heater, 16 ... Shutter, 20
... Substrate loading / unloading section, 21 ... Gas introduction section, 22 ...
・ Gas exhaust part, 23 ・ ・ ・ Elevator mechanism, 24 ・ ・ ・
Quartz boat, 30, 60 ... combustion chamber, 31, 32, 3
3, 35, 61, 62, 63, 65 ... piping, 34,
64 ... inert gas introduction part, 36, 66 ... heater, 40 ... silicon semiconductor substrate, 41 ... element isolation region, 42 ... silicon oxide film, 43 ... gate electrode, 51 ... resistance heaters, 51A, 151A,
151B ... lamp, 52 ... wafer table, 53 ...
・ Gate valve, 54: Gas introduction part, 55: Gas exhaust part

Claims (35)

[Claims] (A) a combustion chamber for generating steam by burning hydrogen gas with oxygen gas; and (B) a silicon oxide film on the surface of the silicon layer by the steam supplied to the combustion chamber and supplied from the combustion chamber. A process for forming a silicon oxide film using an oxide film forming apparatus comprising: (a) an inert gas atmosphere maintained at a temperature at which silicon atoms do not desorb from the surface of the silicon layer. After the substrate having the silicon layer is disposed in the processing chamber, at least after the supply of oxygen gas to the combustion chamber is started, the supply of hydrogen gas to the combustion chamber generates steam in the combustion chamber and is supplied to the processing chamber. In the meantime, an inert gas is supplied into the processing chamber, and then the steam is supplied from the combustion chamber while maintaining the atmosphere at a temperature at which silicon atoms do not desorb from the surface of the silicon layer. Forming a silicon oxide film on the surface of the silicon layer by (b) raising the ambient temperature of the processing chamber to a desired temperature; and (c) maintaining the atmosphere at the desired temperature. Forming a silicon oxide film further using water vapor supplied from the combustion chamber. 2. In the step (a), after forming a silicon oxide film on the surface of the silicon layer, stopping supply of hydrogen gas to the combustion chamber, supplying oxygen gas to the combustion chamber for a predetermined time, 2. The method for forming a silicon oxide film according to claim 1, wherein an inert gas is supplied into the processing chamber. 3. In the step (c), before the further formation of the silicon oxide film by the water vapor, at least after the start of the supply of the oxygen gas to the combustion chamber, the supply of the hydrogen gas to the combustion chamber causes the water vapor to be turned on. 2. The method according to claim 1, wherein an inert gas is supplied into the processing chamber until the gas is generated in the processing chamber and supplied to the processing chamber. 4. In the step (c), after forming a silicon oxide film on the surface of the silicon layer and stopping supply of hydrogen gas to the combustion chamber, supplying oxygen gas to the combustion chamber for a predetermined time. 2. The method for forming a silicon oxide film according to claim 1, wherein an inert gas is supplied into the processing chamber. 5. In order to prevent incomplete combustion of hydrogen gas,
2. The method for forming a silicon oxide film according to claim 1, wherein oxygen gas is supplied into the processing chamber. 6. The method according to claim 1, wherein the temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which the bond between the atoms terminating the silicon layer surface and the silicon atoms is not broken. Of forming a silicon oxide film. 7. The silicon according to claim 6, wherein the temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which a Si—H bond is not broken or a temperature at which a Si—F bond is not broken. A method for forming an oxide film. 8. The method for forming a silicon oxide film according to claim 1, wherein the water vapor in the step (a) and / or the step (c) is diluted with an inert gas. 9. The method for forming a silicon oxide film according to claim 1, wherein the water vapor in the step (a) and / or the step (c) contains a halogen element. 10. The method for forming a silicon oxide film according to claim 9, wherein the halogen element is chlorine. 11. The chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in steam is 0.02 to 10% by volume.
The method for forming a silicon oxide film according to claim 10, wherein: 12. The method according to claim 1, wherein the atmosphere in the step (b) is an inert gas atmosphere. 13. The method for forming a silicon oxide film according to claim 12, wherein the inert gas atmosphere contains a halogen element. 14. The method for forming a silicon oxide film according to claim 13, wherein the halogen element is chlorine. 15. The chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in steam is 0.02 to 10% by volume.
The method for forming a silicon oxide film according to claim 14, wherein: 16. The method according to claim 1, wherein the atmosphere in the step (b) is an oxidizing atmosphere containing water vapor supplied from a combustion chamber. 17. The method for forming a silicon oxide film according to claim 16, wherein the atmosphere in the step (b) is an oxidizing atmosphere in which steam supplied from a combustion chamber is diluted with an inert gas. 18. The method for forming a silicon oxide film according to claim 16, wherein the water vapor in the atmosphere in the step (b) contains a halogen element. 19. The method for forming a silicon oxide film according to claim 18, wherein the halogen element is chlorine. 20. Chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in steam is 0.02 to 10% by volume.
20. The method according to claim 19, wherein: 21. The method according to claim 1, wherein a heat treatment is performed on the formed silicon oxide film after the step (c). 22. The heat treatment atmosphere is an inert gas atmosphere containing a halogen element.
2. The method for forming a silicon oxide film according to item 1. 23. The method according to claim 22, wherein the halogen element is chlorine. 24. The silicon oxide film according to claim 23, wherein the chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 25. The method according to claim 21, wherein the heat treatment is performed at a temperature of 700 to 950 ° C. 26. The method according to claim 25, wherein the heat treatment is a furnace annealing process. 27. The method for forming a silicon oxide film according to claim 21, wherein the atmosphere for the heat treatment is a nitrogen-based gas atmosphere. 28. The method according to claim 21, wherein an ambient temperature at the time of performing a heat treatment on the formed silicon oxide film is higher than an ambient temperature at the time of forming the silicon oxide film in the step (c). A method for forming a silicon oxide film. 29. After the formation of the silicon oxide film in the step (c) is completed, the atmosphere is switched to an inert gas atmosphere containing a halogen element, and then the temperature is raised to an ambient temperature for performing a heat treatment. A method for forming a silicon oxide film according to claim 28. 30. The method according to claim 29, wherein the halogen element is chlorine. 31. The silicon oxide film according to claim 30, wherein the chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 32. The method according to claim 1, wherein the silicon layer comprises an epitaxial silicon layer formed on the substrate. 33. (A) a combustion chamber for generating steam by burning hydrogen gas with oxygen gas; and (B) a silicon oxide film formed on the surface of the silicon layer by the steam supplied to the combustion chamber and supplied from the combustion chamber. And (C) a pipe connecting the combustion chamber and the processing chamber, wherein the pipe is provided with an inert gas introduction part. Oxide film forming apparatus. 34. A piping including an inert gas introduction part is provided with a heating means for preventing steam generated in the combustion chamber from dew condensation before reaching the processing chamber. 34. The oxide film forming apparatus according to claim 33. 35. An inert gas introduction part is provided in a pipe so that an inert gas flowing into the pipe from an inert gas introduction part provided in the pipe does not flow into the combustion chamber side. An apparatus for forming an oxide film according to claim 33.