JP3588994B2 - Method of forming oxide film and method of manufacturing p-type semiconductor device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of forming an oxide film and a method of manufacturing a p-type semiconductor device, and more particularly, to a method of forming an oxide film having a nitrided surface and a method of applying such an oxide film to the formation of a gate oxide film. The present invention relates to a method for manufacturing a semiconductor device.
[0002]
[Prior art]
For example, in manufacturing a MOS type semiconductor device based on a silicon semiconductor substrate, it is necessary to form a gate oxide film made of a silicon oxide film on the surface of the silicon semiconductor substrate. Also, in manufacturing a thin film transistor (TFT), it is necessary to form a gate oxide film made of a silicon oxide film on the surface of a silicon layer provided on an insulating substrate. It is not an exaggeration to say that such a silicon oxide film is responsible for the reliability of the semiconductor device. Therefore, the silicon oxide film is always required to have high dielectric breakdown voltage and long-term reliability.
[0003]
With the increase in the degree of integration of semiconductor devices, the thickness of the gate oxide film of a MOS type semiconductor device is also becoming thinner, and it is expected that the thickness of the gate oxide film in a semiconductor device having a gate length of 0.1 μm will be about 3 nm. The methods for forming the silicon oxide film are roughly classified into two methods, a dry oxidation method using dry oxygen as an oxidizing species and a humidifying oxidation method using steam as an oxidizing species. The dry oxidation method is a method for forming a silicon oxide film on the surface of a silicon semiconductor substrate by supplying sufficiently dried oxygen to a heated silicon semiconductor substrate. Further, the humidification oxidation method is a method in which a silicon oxide film is formed on the surface of a silicon semiconductor substrate by supplying a high-temperature carrier gas containing water vapor to the silicon semiconductor substrate. In general, a silicon oxide film formed by a humidification oxidation method has higher reliability than a silicon oxide film formed by a dry oxidation method.
[0004]
One type of humidification oxidation method is pyrogenic oxidation method. This method is a method of generating water vapor by burning pure hydrogen gas in order to enhance the reproducibility of the humidification oxidation method and eliminate the need for controlling the amount of water. This pyrogenic method can generate water vapor most stably, so that a uniform silicon oxide film can be formed. In addition, since a gas is used as a raw material for generating steam, there is an advantage that impurities can be easily controlled.
[0005]
2. Description of the Related Art In recent years, the voltage of CMOS transistors has been reduced in order to reduce power consumption. For this reason, sufficiently low and symmetric threshold voltages are required for PMOS semiconductor devices and NMOS semiconductor devices. . In order to cope with such a demand, in a PMOS semiconductor device, a gate electrode composed of a polysilicon layer containing a p-type impurity is replaced with a gate electrode composed of a polysilicon layer containing an n-type impurity. Is used. However, boron atoms (B), which are commonly used p-type impurities, easily pass from the gate electrode to the silicon semiconductor substrate through the gate oxide film by various heat treatments in the semiconductor device manufacturing process after the gate electrode is formed. , The threshold voltage of the PMOS semiconductor element is varied. Such a phenomenon becomes more conspicuous when the gate oxide film is made thinner to reduce the voltage.
[0006]
[Problems to be solved by the invention]
When an attempt is made to form a thin silicon oxide film, the humidification oxidation method has a higher oxidation rate than the dry oxidation method. For example, it is necessary to lower the oxidation temperature and shorten the oxidation time. However, there is a problem that shortening the oxidation time prevents uniformization of the thickness of the silicon oxide film. Therefore, when a thin silicon oxide film is formed by using the humidifying oxidation method, the oxidation rate must be suppressed by another method.
[0007]
As a method for suppressing the oxidation rate, there is a method in which water vapor is generated under reduced pressure and a silicon oxide film is formed under reduced pressure. As described above, when the silicon oxide film is formed under reduced pressure, the supply rate of the oxidizing species is small, so that the oxidation rate can be suppressed. However, in the method of generating steam under such reduced pressure, the operation of the hydrogen gas combustion device for generating steam is not stable. That is, it is difficult to stably burn hydrogen gas under reduced pressure, and as a result, there is a problem that it is difficult to stably form a thin silicon oxide film while suppressing the oxidation rate.
[0008]
Further, in order to suppress the fluctuation of the threshold voltage of the PMOS semiconductor element due to the diffusion of the boron atoms (B) into the silicon semiconductor substrate, a method of introducing nitrogen atoms into the gate oxide film has been attempted. The effect of suppressing boron atom diffusion has also been confirmed. As a method for introducing nitrogen atoms into a gate oxide film, for example, a so-called plasma nitriding method for generating nitrogen plasma by performing discharge in a nitrogen gas atmosphere is described in the document "Ultrathin nitrogen-profile engineered gate dielectric films", S.I. V. Hattangdy, et al. , 1996, IEDM. In the plasma nitridation method described in this document, since only the surface of the gate oxide film is nitrided, nitrogen enters the silicon semiconductor substrate as in the case of introducing nitrogen atoms into the gate oxide film by the thermal nitridation method. As a result, there is no adverse effect on semiconductor device characteristics such as a reduction in current driving capability.
[0009]
However, in the plasma nitriding method described in this document, since the silicon oxide film is formed based on the thermal oxidation method, the formation of the silicon oxide film and the plasma nitridation of the silicon oxide film are performed by different apparatuses, and moreover It must be performed in the process of the process. That is, there is a problem that the number of manufacturing steps of the semiconductor device is increased and a manufacturing time of the semiconductor device is prolonged, or a problem that two types of devices, an oxidizing device and a plasma nitriding device, are required.
[0010]
Therefore, an object of the present invention is to make it possible to stably form a thin oxide film by a humidifying oxidation method, and also to surely suppress the diffusion of boron atoms in forming a gate electrode of a p-type semiconductor device. An object of the present invention is to provide a method for forming a p-type semiconductor device, in which a method for forming an oxide film and a method for forming the oxide film are applied to the formation of a gate oxide film. It is a further object of the present invention to provide a method for forming an oxide film capable of nitriding only the surface of the oxide film in one apparatus, and a p-type semiconductor in which such a method for forming an oxide film is applied to the formation of a gate oxide film. An object of the present invention is to provide a method for manufacturing an element.
[0011]
[Means for Solving the Problems]
The method for forming an oxide film of the present invention for achieving the above object is as follows:
(A) irradiating the hydrogen gas and the oxygen gas with electromagnetic waves to generate steam, oxidizing the surface of the semiconductor layer using the steam, and thereby forming an oxide film on the surface of the semiconductor layer;
(B) a step of nitriding the surface of the oxide film by nitrogen molecules or nitrogen molecule ions in an excited state generated by irradiating a nitrogen-based gas with electromagnetic waves;
Characterized by comprising:
[0012]
Further, a method for manufacturing a p-type semiconductor device of the present invention for achieving the above object, comprises:
(A) forming a gate oxide film on the surface of the semiconductor layer;
(B) forming a gate electrode made of a silicon layer containing a p-type impurity on the gate oxide film;
A method for manufacturing a p-type semiconductor device comprising:
Step (A) includes:
(A) irradiating the hydrogen gas and the oxygen gas with electromagnetic waves to generate steam, oxidizing the surface of the semiconductor layer using the steam, and thereby forming an oxide film on the surface of the semiconductor layer;
(B) nitriding the surface of the oxide film with nitrogen molecules or nitrogen molecule ions in an excited state generated by irradiating a nitrogen-based gas with an electromagnetic wave, thereby forming a gate oxide film;
Characterized by comprising:
[0013]
In the method of manufacturing a p-type semiconductor device according to the present invention, the formation of the gate electrode made of a silicon layer containing a p-type impurity (for example, a polysilicon layer or an amorphous silicon layer) includes, for example, a p-type impurity (for example, boron). A method of patterning a silicon layer after forming a silicon layer based on a CVD method, and a method of forming a silicon layer containing no impurities by a CVD method and then forming a p-type impurity (for example, boron or BF). ₂ ) Is implanted into a silicon layer by an ion implantation method, and then the silicon layer is patterned. A silicon layer containing no impurities is formed by a CVD method and then patterned, and then a p-type impurity (for example, boron or BF ₂ ) Into the silicon layer by ion implantation. In the step (B), after forming a silicon layer containing a p-type impurity, a silicide layer is formed on the silicon layer, and then the silicide layer and the silicon layer are patterned to form a gate electrode having a polycide structure. May be formed.
[0014]
In the method of forming an oxide film or the method of manufacturing a p-type semiconductor device of the present invention (hereinafter, these may be simply referred to as the method of the present invention), for example, microwaves having a frequency of 2.45 GHz may be used as electromagnetic waves. Can be used. In a state in which water vapor generated based on hydrogen gas and oxygen gas is diluted with an inert gas such as nitrogen, argon, helium, neon, krypton, or xenon, or using these inert gases as a carrier gas, An oxide film may be formed on the surface of the layer.
[0015]
In the present invention, a nitrogen gas (N ₂ Gas), NO, N ₂ O, NO ₂ For example, a gas that is a compound of a nitrogen atom and an oxygen atom can be used.
[0016]
In the method of the present invention, it is preferable that the step (a) and the step (b) are performed in the same processing chamber from the viewpoint of simplification of the device configuration or reduction of the time for forming an oxide film or a gate oxide film.
[0017]
When manufacturing a MOS type semiconductor device based on a silicon semiconductor substrate, conventionally, before forming a gate oxide film, NH ₄ OH / H ₂ O ₂ Wash with aqueous solution and add HCl / H ₂ O ₂ The surface of the silicon semiconductor substrate is cleaned by RCA cleaning, which is cleaning with an aqueous solution, to remove fine particles and metal impurities from the surface. By the way, 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. The thickness of such a silicon oxide film is not uniform, and a cleaning liquid component remains in the silicon oxide film. Therefore, the silicon semiconductor substrate is immersed in an aqueous solution of hydrofluoric acid to remove the silicon oxide film, and further to remove chemical components with pure water. Thereby, it is possible to obtain a surface of the silicon semiconductor substrate that is mostly terminated with hydrogen and extremely partially terminated with fluorine. In this specification, obtaining a surface of a silicon semiconductor substrate that is mostly terminated with hydrogen and a very small portion is terminated with fluorine is referred to as exposing the surface of the silicon semiconductor substrate in this specification. I do. Thereafter, a silicon oxide film is formed on the surface of the silicon semiconductor substrate.
[0018]
By the way, if the atmosphere before forming the silicon oxide film based on the humidifying oxidation method is a high-temperature nitrogen gas atmosphere, the surface of the silicon semiconductor substrate becomes rough (unevenness). Such a phenomenon occurs because a part of the Si—H bond or a part of the Si—F bond formed on the surface of the silicon semiconductor substrate by washing with the hydrofluoric acid aqueous solution and the pure water increases hydrogen or fluorine. It is considered to be lost due to thermal desorption and caused by an etching phenomenon occurring on the surface of the silicon semiconductor substrate. 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.
[0019]
Therefore, in order to avoid the occurrence of such a phenomenon that the surface (roughness) of the semiconductor layer is roughened, in the method of the present invention, in the step (a), the semiconductor layer is mainly removed from the surface of the semiconductor layer. It is preferable to start formation of an oxide film on the surface of the semiconductor layer in a state where the semiconductor layer is kept at a temperature at which constituent atoms do not desorb. The temperature at which atoms mainly constituting the semiconductor layer do not desorb from the surface of the semiconductor layer is a temperature at which bonds between atoms terminating the surface of the semiconductor layer and atoms mainly constituting the semiconductor layer are not broken. Is desirable. When the atoms mainly constituting the semiconductor layer are Si, that is, when the semiconductor layer is composed of a silicon semiconductor substrate, a single crystal silicon layer, a polysilicon layer, or an amorphous silicon layer, the semiconductor layer is removed from the surface of the semiconductor layer. It is desirable that the temperature at which the main constituent atoms do not desorb be a temperature at which the Si—H bond on the surface of the semiconductor layer is not broken, or a temperature at which the Si—F bond on the surface of the semiconductor layer is not broken. When a silicon semiconductor substrate having a plane orientation of (100) is used as a semiconductor layer, most of the hydrogen atoms on the surface of the silicon semiconductor substrate are bonded one by one to two bonds of silicon atoms. -H termination structure. However, in a portion where the surface state of the silicon semiconductor substrate is broken (for example, a step forming portion), a termination structure in which a hydrogen atom is bonded to only one bond of a silicon atom, or a three-bonded silicon atom There is a terminal structure in which a hydrogen atom is bonded to each hand. Usually, the remaining bonds of silicon atoms are bonded to silicon atoms inside the crystal. The expression “Si—H bond” in this specification refers to a terminal structure in which a hydrogen atom is bonded to each of two silicon atoms, and a hydrogen atom is bonded to only one silicon atom. The terminating structure in a state in which a hydrogen atom is bonded to each of the three bonding hands of a silicon atom or the terminating structure in a state in which a hydrogen atom is bonded to each of three bonding hands of a silicon atom is included. The temperature at which the formation of the oxide film on the surface of the semiconductor layer is started is more specifically a temperature at which water vapor does not condense on the semiconductor layer, preferably 200 ° C. or more, more preferably 300 ° C. or more. This is desirable in terms of throughput.
[0020]
In the method of the present invention, in the step (a), the temperature of the semiconductor layer when the formation of the oxide film is completed may be higher than the temperature of the semiconductor layer when the formation of the oxide film is started. In this case, the temperature of the semiconductor layer when the formation of the oxide film is completed is preferably 600 to 1200 ° C., preferably 700 to 1000 ° C., and more preferably 750 to 900 ° C. It is not limited to a value. The temperature may be raised stepwise (stepwise) or continuously.
[0021]
When the temperature is raised stepwise, after the formation of an oxide film on the surface of the semiconductor layer at a temperature at which atoms mainly constituting the semiconductor layer do not desorb from the surface of the semiconductor layer, the semiconductor layer is kept for a predetermined period. A first oxide film forming step of forming an oxide film while holding the semiconductor layer in a temperature range where atoms mainly constituting the semiconductor layer do not desorb from the surface of the semiconductor layer, and mainly forming the semiconductor layer from the surface of the semiconductor layer It is preferable to include a second oxide film forming step of further forming an oxide film at a temperature higher than a temperature range in which atoms do not desorb until a desired thickness is obtained. The temperature at which the oxide film is formed in the second oxide film forming step is desirably 600 to 1200 ° C., preferably 700 to 1000 ° C., and more preferably 750 to 900 ° C. Note that the upper limit of the semiconductor layer holding temperature range in the first oxide film forming step may be 500 ° C., preferably 450 ° C. or less, more preferably 400 ° C. The final thickness of the oxide film after the second oxide film forming step may be a predetermined thickness required for the semiconductor element. On the other hand, the thickness of the oxide film after the first oxide film forming step is preferably as thin as possible. However, the plane orientation of a silicon semiconductor substrate currently used for manufacturing a semiconductor device is almost (100), and no matter how the surface of the silicon semiconductor substrate is smoothed, the surface of the silicon semiconductor substrate must be (100). A step called a 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 oxide film after the first oxide film forming step is preferably 1 nm or more when a (100) silicon semiconductor substrate is used as the semiconductor layer, but is not limited thereto.
[0022]
A temperature raising step may be included between the first oxide film forming step and the second oxide film forming step. In this case, the atmosphere in the temperature raising step is preferably an inert gas atmosphere or a reduced pressure atmosphere, or an oxidizing atmosphere containing water vapor. Here, examples of the inert gas include a nitrogen gas, an argon gas, and a helium gas. In addition, the inert gas or the gas containing water vapor in the atmosphere in the temperature raising step may contain a halogen element. Thereby, the characteristics of the oxide film formed in the first oxide film forming step can be further improved. That is, when the atoms mainly constituting the semiconductor layer are Si, silicon dangling bonds (Si.) And SiOH, which are defects that can be generated in the first oxide film forming step, react with the halogen element in the temperature increasing step, and silicon As a result of termination of the dangling bond or dehydration reaction, these defects which are reliability deterioration factors are eliminated. In particular, the elimination of these defects is effective for the initial silicon oxide film formed in the first oxide film forming step. Examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the inert gas or the gas containing water vapor include hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , HBr, NF ₃ Can be mentioned. The content of the halogen element in the gas containing an inert gas or water vapor is 0.001 to 10% by volume, preferably 0.005 to 10% by volume, more preferably 0.02% by volume, based on the form of the molecule or the compound. -10% by volume. For example, when using hydrogen chloride gas, the content of hydrogen chloride gas in a gas containing an inert gas or water vapor is preferably 0.02 to 10% by volume. Note that the atmosphere in the temperature raising step may be an atmosphere containing water vapor diluted with an inert gas.
[0023]
In the method of the present invention, the gas atmosphere containing water vapor during the formation of the oxide film may contain a halogen element. As a result, an oxide film having excellent time-zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained. 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 gas containing water vapor include hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , HBr, NF ₃ Can be mentioned. The content of the halogen element in the gas containing 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. It is. For example, when hydrogen chloride gas is used, the content of hydrogen chloride gas in the gas containing water vapor is desirably 0.02 to 10% by volume.
[0024]
In order to further improve the characteristics of the formed oxide film, in the method of the present invention, it is preferable to perform a heat treatment on the formed oxide film between the steps (a) and (b).
[0025]
In this case, it is desirable that the atmosphere of the heat treatment be an inert gas atmosphere containing a halogen element. By subjecting the oxide film to heat treatment in an inert gas atmosphere containing a halogen element, an oxide film having excellent time-zero dielectric breakdown (TZDB) characteristics and time-dependent dielectric breakdown (TDDB) characteristics can be obtained. Examples of the inert gas in the heat treatment include a nitrogen gas, an argon gas, and a helium gas. In addition, examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the inert gas include hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , HBr, NF ₃ Can be mentioned. The content of the halogen element in the inert gas 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 compound. is there. 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.
[0026]
In the method of the present invention, it is preferable to perform heat treatment in the same processing chamber. The temperature of the heat treatment is 700 to 1200 ° C, preferably 700 to 1000 ° C, more preferably 700 to 950 ° C. Further, the time of the heat treatment is preferably 1 to 10 minutes when performing the single-wafer processing, and 5 to 60 minutes, preferably 10 to 40 minutes, more preferably 20 to 30 when performing the batch processing. Minutes.
[0027]
When heat treatment is performed in the method of the present invention, it is desirable that the temperature of the atmosphere when the heat treatment is performed on the formed oxide film is higher than the temperature when the formation of the oxide film is completed. In this case, after the formation of the oxide film is completed, the atmosphere in the processing chamber is switched to an inert gas atmosphere, and then the temperature may be increased to the ambient temperature for performing the heat treatment. After switching to the active gas atmosphere, it is preferable to raise the temperature to the ambient temperature for performing the heat treatment. Here, examples of the inert gas include a nitrogen gas, an argon gas, and a helium gas. Examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the inert gas include hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , HBr, NF ₃ Can be mentioned. The content of the halogen element in the inert gas 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 compound. is there. 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.
[0028]
Usually, before forming a silicon oxide film on the surface of a silicon semiconductor substrate, NH 3 ₄ OH / H ₂ O ₂ Wash with aqueous solution and add HCl / H ₂ O ₂ After cleaning the surface of the silicon semiconductor substrate by RCA cleaning, which is cleaning with an aqueous solution, removing fine particles and metal impurities from the surface, the silicon semiconductor substrate is cleaned with a hydrofluoric acid aqueous solution and pure water. However, when the silicon semiconductor substrate is subsequently exposed to the air, the surface of the silicon semiconductor substrate is contaminated, moisture and organic substances adhere to the surface of the silicon semiconductor substrate, or Si atoms on the surface of the silicon semiconductor substrate become hydroxyl groups ( OH) (see, for example, the document "Highly-reliable Gate Oxide Formation for Giga-Scale LSIs by using Closed Wet Cleaning System and Wet Oxidation, Utilization of the U.S.A., U.S.A. Device Meeting Technical Digest 95, pp 855-858). In such a case, if the formation of the oxide film is started as it is, moisture, an organic substance, or, for example, Si-OH is taken into the formed silicon oxide film, and the formed silicon oxide film has reduced characteristics or It can cause the generation of defective portions. Note that a defect portion is a portion of a silicon oxide film containing a defect such as a silicon dangling bond (Si.) Or a Si-H bond, or a portion where a Si-O-Si bond is compressed by stress or a Si-O- It means a portion of the silicon oxide film including a Si-O-Si bond in which the angle of the Si bond is thick or different from the angle of the Si-O-Si bond in the bulk silicon oxide film. Therefore, in order to avoid the occurrence of such a problem, the method of the present invention includes a step of cleaning the surface of the semiconductor layer before forming the oxide film, and exposing the semiconductor layer after the surface cleaning to the atmosphere. The formation of the oxide film is preferably performed without using an inert gas atmosphere or a vacuum atmosphere from the cleaning of the semiconductor layer surface to the start of the oxide film formation step (for example, the atmosphere from the cleaning of the semiconductor layer surface to the start of the oxide film formation step). Thus, for example, when a silicon semiconductor substrate is used as a semiconductor layer, a silicon oxide film can be formed on the surface of a silicon semiconductor substrate having a surface that is mostly terminated with hydrogen and a part of which is terminated with fluorine, Deterioration of the characteristics of the formed silicon oxide film or occurrence of a defective portion can be prevented.
[0029]
In the formation of the oxide film, hydrogen gas and oxygen gas are introduced into the processing chamber. At this time, in order to prevent a detonation reaction from occurring due to hydrogen gas flowing into the processing chamber and flowing out of the system. In addition, it is desirable to introduce oxygen gas before introducing hydrogen gas into the processing chamber. However, there is a possibility that an oxide film is formed in the semiconductor layer by introduction of oxygen gas into the treatment chamber. Such an oxide film is a dry oxide film and has inferior characteristics to an oxide film formed by a humidifying oxidation method. In order to reliably prevent the formation of such a dry oxide film, for example, a hydrogen gas diluted with an inert gas such as nitrogen gas is first introduced into a processing chamber before the formation of an oxide film, and then the processing is performed. What is necessary is just to introduce oxygen gas into a room. However, in this case, in order to reliably prevent the occurrence of a detonation reaction, the concentration of the hydrogen gas is adjusted so that the hydrogen gas does not react with the oxygen gas and burn, specifically, in air. Below the detonation range (18.3% by volume or less when expressed by volume with air), preferably below the combustion range in air (4.0% by volume or less when expressed by volume with air) ) Or below the detonation range in oxygen (less than 15.0% by volume when expressed as volume% with oxygen), preferably below the combustion range in oxygen (expressed as volume% with oxygen) In this case, the concentration is desirably set to be 4.5% by volume or less.
[0030]
As a semiconductor layer, not only a silicon semiconductor substrate such as a silicon single crystal wafer, but also an epitaxial silicon layer, a polysilicon layer, or an amorphous silicon layer on a semiconductor substrate, and further, a silicon semiconductor substrate and a semiconductor element are formed on these layers Means an underlayer on which an oxide film is to be formed. Forming an oxide film on a semiconductor layer includes not only forming an oxide film on a semiconductor layer formed on or above a semiconductor substrate or the like, but also forming an oxide film on the surface of the semiconductor substrate. Incidentally, the silicon single crystal wafer may be a wafer produced by any method such as a CZ method, an MCZ method, a DLCZ method, an FZ method, or may be a wafer which has been previously subjected to hydrogen annealing. Further, the semiconductor layer may be made of Si-Ge.
[0031]
The method of forming an oxide film according to the present invention includes, for example, forming a gate oxide film of a MOS transistor, forming an interlayer insulating film and an element isolation region, forming a gate oxide film of a top gate or bottom gate thin film transistor, and a tunnel oxide film of a flash memory. For forming an oxide film in various semiconductor devices.
[0032]
In the oxygen plasma generated by the microwave discharge, the ground state O ₂ (X ³ Σg ⁻ ) Is the excited state O ₂ (A ³ Σu ⁺ ) Or O ₂ (B ³ Σu ⁻ ), And each dissociates into oxygen atoms as in the following formula.
[0033]
Embedded image
O ₂ (X ³ Σg ⁻ ) + E → O ₂ (A ³ Σu ⁺ ) + E Equation (1-1)
O ₂ (A ³ Σu ⁺ ) + E → O ( ³ P) + O ( ³ P) + e Equation (1-2)
O ₂ (X ³ Σg ⁻ ) + E → O ₂ (B ³ Σu ⁻ ) + E Equation (1-3)
O ₂ (B ³ Σu ⁻ ) + E → O ( ³ P) + O ( ¹ D) + e Formula (1-4)
[0034]
Therefore, excited oxygen molecules and oxygen atoms are present in the oxygen plasma, and these become reactive species. Here hydrogen H ₂ Is introduced, the following plasma is generated.
[0035]
Embedded image
H ₂ + E → 2H Formula (2)
[0036]
Then, of the oxygen plasma, for example, the oxygen plasma generated by the equation (1-2) and the hydrogen plasma generated by the equation (2) react to generate water vapor. Then, the surface of the heated semiconductor layer is oxidized by the water vapor, and an oxide film is formed on the surface of the semiconductor layer.
[0037]
Embedded image
2H + O ( ³ P) → H ₂ O Formula (3)
[0038]
In the method of the present invention, since steam is generated based on such a reaction between oxygen plasma and hydrogen plasma, for example, steam can be easily and reliably generated even under reduced pressure, and the oxidation rate is reduced. In a controlled state, a thin oxide film can be formed by a humidifying oxidation method.
[0039]
On the other hand, nitrogen (N ₂ ) When using gas, nitrogen N ₂ Is excited in a microwave plasma, for example, as in the following equation. That is, electrons existing in the plasma are excited, and nitrogen molecules and nitrogen molecular ions excited by inelastic collision of the electrons with nitrogen molecules are generated. These excited nitrogen molecules and nitrogen molecule ions are bonded to oxygen atoms and atoms mainly constituting the semiconductor layer on the surface of the oxide film (for example, when the atoms mainly constituting the semiconductor layer are Si, Si—O The bond is cut to form a nitrided oxide (for example, a Si—O—N bond), and the surface of the oxide film is nitrided. The composition of the surface of the oxide film is SiO 2 when atoms mainly constituting the semiconductor layer are Si. _X N _Y It is represented by
[0040]
Embedded image
N ₂ (X ¹ Σg) + e → N ₂ (A ³ Σu ⁺ ) + E Equation (4-1)
N ₂ (N ¹ Σg) + e → N ₂ (C ³ Πu) + e Equation (4-2)
N ₂ (C ³ Πu) + e → N ₂ (B ³ Πg) + hν formula (4-3)
N ₂ (B ³ Πg) + e → N ₂ (A ³ Σu ⁺ ) + Hν formula (4-4)
[0041]
In the method of the present invention, since the oxide film or the gate oxide film is formed based on the irradiation of the hydrogen gas, the oxygen gas, and the nitrogen-based gas with electromagnetic waves, the oxide film is essentially formed in one oxide film forming apparatus. Alternatively, a gate oxide film can be formed, and the configuration of an apparatus for forming an oxide film or a gate oxide film can be simplified. In addition, since the steam is generated by irradiating the hydrogen gas and the oxygen gas with the electromagnetic wave, the steam is easily and reliably generated in a state where the oxidation rate is suppressed and controlled, that is, for example, even under a reduced pressure. This makes it possible to form a thin oxide film by the humidifying oxidation method. In addition, since the oxide film is formed by an oxidation method using water vapor, an oxide film having excellent time-dependent dielectric breakdown (TDDB) characteristics can be obtained.
[0042]
In addition, since only the surface of the oxide film is nitrided, semiconductor device characteristics such as a decrease in current driving capability due to the invasion of nitrogen into the silicon semiconductor substrate, such as the introduction of nitrogen atoms into the gate oxide film by thermal nitridation, There is no adverse effect on Further, since the oxide film is nitrided, for example, boron atoms pass through the gate oxide film to reach the silicon semiconductor substrate by various heat treatments in the semiconductor device manufacturing process after the formation of the gate electrode, and the threshold voltage of the PMOS semiconductor element is reduced. A phenomenon such as fluctuation can be reliably avoided.
[0043]
【Example】
Hereinafter, the present invention will be described based on embodiments with reference to the drawings.
[0044]
(Example 1)
FIG. 1 shows a conceptual diagram of a single wafer type oxide film forming apparatus suitable for carrying out the method of the present invention. The oxide film forming apparatus includes a processing chamber 10, a stage 11 on which a semiconductor layer (a silicon semiconductor substrate 20 in the first embodiment) is mounted, a magnet 13 provided outside the processing chamber 10, And a gas introduction section 16A, 16B, 16C disposed at the top of the processing chamber 10. The processing chamber 10 includes a plasma generation region 10A and a reaction region 10B. Further, a lamp serving as a heating unit 12 for heating the silicon semiconductor substrate 20 is housed in the stage 11. A magnetron 15 is attached to the microwave waveguide 14, and a microwave of 2.45 GHz is generated by the magnetron 15, and the microwave is introduced into the plasma generation region 10A of the processing chamber 10 through the microwave waveguide 14. You. Further, hydrogen gas, oxygen gas, and nitrogen gas are introduced into the processing chamber 10 from each of the gas introduction units 16A, 16B, and 16C. In addition, an inert gas (for example, nitrogen gas) is introduced into the processing chamber 10 from a gas introduction unit 17 provided on a side surface of the processing chamber 10. Various gases introduced into the processing chamber 10 are exhausted out of the system from a gas exhaust unit 18 provided in a lower part of the processing chamber 10.
[0045]
In Example 1, a silicon semiconductor substrate was used as a semiconductor layer. In the first embodiment, the oxide film is formed on the surface of the semiconductor layer at a temperature at which atoms mainly constituting the semiconductor layer do not desorb from the surface of the semiconductor layer. A first oxide film forming step of forming an oxide film by holding the semiconductor layer within a temperature range in which atoms mainly constituting the semiconductor layer do not desorb from the surface of the semiconductor layer, and removing the semiconductor layer from the surface of the semiconductor layer. A second oxide film forming step of further forming an oxide film at a temperature higher than the temperature range in which the main constituent atoms do not desorb is performed until a desired thickness is obtained. The method of forming an oxide film and the method of manufacturing a p-type semiconductor device of the present invention using the oxide film forming apparatus shown in FIG. 1 will be described below with reference to FIG. It will be described with reference to FIG.
[0046]
[Step-100]
First, an element isolation region 21 having a LOCOS structure is formed by a known method on a silicon semiconductor substrate 20 which is an N-type silicon wafer (manufactured by a CZ method) having a diameter of 8 inches and doped with phosphorus. Channel stop ion implantation and threshold adjustment ion implantation are performed. Note that the element isolation region may have a trench structure, or may have a combination of a LOCOS structure and a trench structure. Thereafter, fine particles and metal impurities on the surface of the silicon semiconductor substrate 20 are removed by RCA cleaning, and then the surface of the silicon semiconductor substrate 20 is cleaned with a 0.1% aqueous hydrofluoric acid solution and pure water. The surface is exposed (see FIG. 2A). Most of the surface of the silicon semiconductor substrate 20 is terminated with hydrogen, and a very small portion is terminated with fluorine.
[0047]
[Step-110]
Next, the silicon semiconductor substrate 20 is carried into the oxide film forming apparatus shown in FIG. 1 from a door (not shown) and placed on the stage 11, and then an inert gas (for example, nitrogen gas) is supplied from the gas introduction unit 17 to the processing chamber. Introduce into 10. Then, the silicon semiconductor substrate 20 is heated to 300 ° C. by the heating means 12. At this temperature, the Si-H bond on the surface of the semiconductor layer is not broken. Therefore, no irregularities (roughness) are generated on the surface of the semiconductor layer (the silicon semiconductor substrate in the first embodiment).
[0048]
[Step-120]
Then, while introducing an inert gas (for example, nitrogen gas) as a diluting gas from the gas introduction unit 17 into the processing chamber 10, hydrogen gas and oxygen gas are introduced into the processing chamber 10 from the gas introduction units 16 </ b> A and 16 </ b> B. Is introduced. At the same time, microwave power is supplied to the magnetron 15, and the microwave of 2.45 GHz generated by the magnetron 15 is introduced into the plasma generation region 10 </ b> A of the processing chamber 10 via the microwave waveguide 14. Thereby, that is, by irradiating the hydrogen gas and the oxygen gas with the electromagnetic waves, the reactions of the above-described equations (1-1) to (1-4) and the reactions of the equations (2) and (3) occur. Water vapor is generated. The generated steam reaches the reaction region 10B located below the processing chamber 10, and the surface of the semiconductor layer (specifically, the silicon semiconductor substrate 20) heated by the heating unit 12 is oxidized. Thus, an oxide film (a silicon oxide film in Example 1) can be formed on the surface of the semiconductor layer. Table 1 shows the conditions for forming the oxide film. In the first oxide film forming step, an oxide film having a thickness of 1 nm is formed.
[0049]
[Table 1]
Microwave power: 10kW
Microwave frequency: 2.45 GHz
Oxygen gas flow rate: 10 SLM
Hydrogen gas flow rate: 0.2 SLM
Inert gas flow rate: 10 SLM
Substrate temperature: 300 ° C
[0050]
[Step-130]
After that, the supply of the microwave power to the magnetron 15 and the introduction of the hydrogen gas and the oxygen gas into the processing chamber 10 are stopped, and the introduction of the inert gas from the gas introduction unit 17 into the processing chamber 10 is continued. The temperature of the silicon semiconductor substrate is raised to 800 ° C. by the heating means 12. Since an oxide film has already been formed on the surface of the semiconductor layer, no irregularities (roughness) occur on the surface of the semiconductor layer (the silicon semiconductor substrate in the first embodiment) in this temperature raising step. Next, hydrogen gas and oxygen gas are again introduced into the processing chamber 10 from the gas introduction unit 16A and the gas introduction unit 16B. At the same time, the microwave power is again supplied to the magnetron 15, and the microwave of 2.45 GHz generated by the magnetron 15 is introduced into the plasma generation region 10 </ b> A of the processing chamber 10 through the microwave waveguide 14. Thereby, that is, by irradiating the hydrogen gas and the oxygen gas with the electromagnetic waves, the reactions of the above-described equations (1-1) to (1-4) and the reactions of the equations (2) and (3) occur. Water vapor is generated. The generated steam reaches the reaction region 10B located below the processing chamber 10, and further oxidizes the surface of the semiconductor layer (specifically, the silicon semiconductor substrate) heated by the heating unit 12. Thus, an oxide film (a silicon oxide film in Example 1) having a total thickness of 4 nm is formed on the surface of the semiconductor layer. Table 2 below shows conditions for forming an oxide film in the second oxide film forming step.
[0051]
[Table 2]
Microwave power: 10kW
Microwave frequency: 2.45 GHz
Oxygen gas flow rate: 10 SLM
Hydrogen gas flow rate: 0.2 SLM
Inert gas flow rate: 10 SLM
Substrate temperature: 800 ° C
[0052]
[Step-140]
After the formation of the oxide film is completed, the supply of the microwave power to the magnetron 15 and the introduction of the hydrogen gas and the oxygen gas into the processing chamber 10 are stopped, and the silicon semiconductor substrate 20 is cooled to room temperature. Next, the introduction of the inert gas from the gas introduction unit 17 into the processing chamber 10 is stopped. Thereafter, a nitrogen gas, which is a nitrogen-based gas, is introduced into the processing chamber 10 from the gas introduction unit 16C. At the same time, microwave power is supplied to the magnetron 15, and the microwave of 2.45 GHz generated by the magnetron 15 is introduced into the plasma generation region 10 </ b> A of the processing chamber 10 via the microwave waveguide 14. In other words, the excited state of the nitrogen molecules or nitrogen molecule ions generated by the reactions of the above formulas (4-1) to (4-4) by irradiating the nitrogen gas with the electromagnetic wave is located below the processing chamber 10. Reaching the reaction region 10B located, the surface of the oxide film (specifically, the silicon oxide film) is nitrided. Thus, the oxide film 22 whose surface is nitrided (in the first embodiment, a silicon oxide film, which corresponds to a gate oxide film) can be formed on the surface of the semiconductor layer. This state is schematically shown in FIG. The illustration of the nitrided portion of the oxide film is omitted in the figure. Table 3 below shows the conditions of nitriding. The reason for setting the temperature of the silicon semiconductor substrate to room temperature is to suppress the diffusion of nitrogen atoms into the silicon semiconductor substrate during the nitriding treatment.
[0053]
[Table 3]
Microwave power: 1kW
Microwave frequency: 2.45 GHz
Nitrogen gas flow rate: 0.4 SLM
Pressure: 0.16Pa
Substrate temperature: room temperature (25 ° C)
[0054]
[Step-150]
Thereafter, the semiconductor layer is unloaded from the oxide film forming apparatus, and then the semiconductor layer is loaded into a known CVD apparatus. Then, a silicon layer containing no impurities (polysilicon layer in Example 1) is formed on the entire surface by a CVD method. Next, the silicon layer is patterned based on a photolithography technique and a dry etching technique. Then, boron ions are implanted into the silicon layer and the silicon semiconductor substrate by an ion implantation method. Thereby, a gate electrode 23 made of a silicon layer (specifically, a polysilicon layer) containing a p-type impurity can be formed on the gate oxide film, and an LDD structure can be formed at the same time (FIG. 2). (C)).
[0055]
[Step-160]
Next, an insulating film is formed on the entire surface, and the insulating film is etched based on the anisotropic dry etching technique to form sidewalls 24 on the side walls of the gate electrode 23. Next, in order to form the source / drain regions 25, boron ions are implanted into the silicon semiconductor substrate by an ion implantation method, and then activation heat treatment of the ion-implanted impurities is performed. Thereafter, an insulating layer 26 is formed on the entire surface by the CVD method, an opening is provided in the insulating layer 26 above the source / drain region 25, and a wiring material layer is formed on the insulating layer 26 including the inside of the opening by a sputtering method. Then, the wiring 27 is formed by patterning the wiring material layer, and a p-type semiconductor element whose schematic partial cross-sectional view is shown in FIG. 2D can be obtained.
[0056]
(Example 2)
The second embodiment is a modification of the method of forming the oxide film and the method of manufacturing the p-type semiconductor device of the first embodiment. Example 2 differs from Example 1 in that a heat treatment is performed on the formed oxide film between the step of forming an oxide film on the surface of the semiconductor layer and the step of nitriding the surface of the oxide film. is there. Hereinafter, a method for forming an oxide film and a method for manufacturing a p-type semiconductor device according to the second embodiment will be described. In the second embodiment, the oxide film forming apparatus shown in FIG. 1 is used.
[0057]
[Step-200]
By performing the same steps as [Step-100] to [Step-130] of the first embodiment, an oxide film having a total thickness of 4 nm (Example 2) is formed on the surface of the semiconductor layer (the silicon semiconductor substrate in the second embodiment). A silicon oxide film).
[0058]
[Step-210]
After that, the supply of the microwave power to the magnetron 15 and the introduction of the hydrogen gas and the oxygen gas into the processing chamber 10 are stopped, and the introduction of the inert gas from the gas introduction unit 17 into the processing chamber 10 is continued. The temperature of the silicon semiconductor substrate is raised to 850 ° C. by the heating means 12. Next, nitrogen gas containing 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 10 from the gas introduction unit 17 and heat treatment is performed for 5 minutes. As a result, an oxide film having excellent time-zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained.
[0059]
[Step-220]
Thereafter, the introduction of nitrogen gas containing 0.1% by volume of hydrogen chloride gas from the gas introduction unit 17 into the processing chamber 10 is stopped, and an inert gas (for example, nitrogen gas) is introduced into the processing chamber 10 from the gas introduction unit 17. Introduce. Then, after the silicon semiconductor substrate is cooled to room temperature, the same steps as [Step-140] to [Step-160] of the first embodiment are performed, whereby a p-type semiconductor element can be obtained.
[0060]
Although the present invention has been described based on the preferred embodiments, 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.
[0061]
For example, in [Step-130] of the first embodiment, the heating means 12 stops the supply of the microwave power to the magnetron 15 and the introduction of the hydrogen gas and the oxygen gas into the processing chamber 10 so that the silicon semiconductor substrate is 800 ° The temperature may be raised to C. Further, in [Step-210] of Example 2, the temperature of the silicon semiconductor substrate was raised to 850 ° C. by a heating unit while introducing an inert gas (for example, nitrogen gas) from the gas introduction unit 17 into the processing chamber 10. Instead, for example, an inert gas (for example, nitrogen gas) containing 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 10 from the gas introduction unit 17 while the temperature of the silicon semiconductor substrate is increased by heating means. To 850 ° C. Further, the atmosphere in each of the first oxide film forming step, the temperature raising step, and the second oxide film forming step may include, for example, a hydrogen chloride gas.
[0062]
In the embodiment, the silicon oxide film is formed exclusively on the surface of the silicon semiconductor substrate, but the silicon oxide film is formed on the epitaxial silicon layer formed on the substrate based on the oxide film forming method of the present invention. Alternatively, a silicon oxide film can be formed on the surface of a polysilicon layer or an amorphous silicon layer formed on an insulating layer formed on a substrate. 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. Further, a silicon oxide film may be formed on the 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 formation of the oxide film including the nitriding treatment can be performed not only in a single wafer process but also in a batch process in which a plurality of semiconductor layers are simultaneously processed.
[0063]
Alternatively, in the embodiment, after the surface of the semiconductor layer is cleaned with a 0.1% aqueous hydrofluoric acid solution and pure water, the semiconductor layer is carried into the oxide film forming apparatus. The atmosphere before the transfer to the apparatus may be an inert gas (eg, nitrogen gas) atmosphere. Note that such an atmosphere may be, for example, an atmosphere of an apparatus for cleaning a surface of a semiconductor layer set to an inert gas atmosphere, and a semiconductor layer (for example, a silicon semiconductor substrate) placed in a transport box filled with an inert gas. As shown in the schematic diagram in FIG. 3, a method for carrying in the oxide film forming apparatus, a surface cleaning apparatus, an oxide film forming apparatus, a transport path, a cluster tool apparatus including a loader and an unloader, and the surface cleaning apparatus. This can be achieved by a method in which the surface of the surface cleaning device, the transfer path, and the processing chamber of the oxide film forming device are set to an inert gas atmosphere by connecting the oxide film forming device to the oxide film forming device.
[0064]
Alternatively, instead of cleaning the surface of the semiconductor layer with a 0.1% aqueous solution of hydrofluoric acid and pure water, the semiconductor layer is subjected to a gas phase cleaning method using anhydrous hydrogen fluoride gas under the conditions exemplified in Table 4. Surface cleaning may be performed. Note that methanol is added to prevent generation of particles. Alternatively, the surface of the semiconductor layer may be cleaned by a gas phase cleaning method using hydrogen chloride gas under the conditions shown in Table 5. The atmosphere in the surface cleaning apparatus and the atmosphere in the transfer path before the start of the surface cleaning of the semiconductor layer or after the completion of the surface cleaning may be an inert gas atmosphere, for example, 1.3 × 10 3. ^-1 Pa (10 ^-3 A vacuum atmosphere of about Torr) may be used. When the atmosphere in the transfer path or the like is a vacuum atmosphere, the atmosphere in the processing chamber 10 of the oxide film forming apparatus when loading the semiconductor layer is set to, for example, 1.3 × 10 ^-1 Pa (10 ^-3 The atmosphere in the processing chamber 10 may be an inert gas (eg, nitrogen gas) atmosphere after setting the vacuum atmosphere of about Torr) and completing the transfer of the semiconductor layer.
[0065]
[Table 4]
Anhydrous hydrogen fluoride gas: 300 SCCM
Methanol vapor: 80 SCCM
Nitrogen gas: 1000 SCCM
Pressure: 0.3Pa
Temperature: 60 ° C
[0066]
[Table 5]
Hydrogen chloride gas / nitrogen gas: 1% by volume
Temperature: 800 ° C
[0067]
By employing these methods, the surface of the semiconductor layer can be kept free from contamination or the like before the formation of the oxide film. As a result, moisture or organic substances, or, for example, Si-OH Can be effectively prevented from deteriorating the properties of the formed oxide film or generating defective portions.
[0068]
As described above, in forming an oxide film, hydrogen gas and oxygen gas are introduced into the processing chamber 10. At this time, hydrogen gas flows into the processing chamber 10 and flows out of the system. In order to prevent a detonation reaction from occurring and to prevent a dry oxide film from being formed on the semiconductor layer, for example, in the [step-120] of the first embodiment, the processing is performed from the gas introduction unit 17. While introducing, for example, an inert gas (for example, nitrogen gas) as a diluent gas at a flow rate of 10 SLM into the chamber 10, hydrogen gas at a flow rate of 0.2 SLM is introduced into the processing chamber 10 from the gas introduction unit 16A, For example, oxygen gas at a flow rate of 10 SLM may be introduced into the processing chamber 10 from the gas introduction unit 16B. Next, microwave power is supplied to the magnetron 15, and the microwave of 2.45 GHz generated by the magnetron 15 is introduced into the plasma generation region 10 </ b> A of the processing chamber 10 via the microwave waveguide 14. By such an operation, the hydrogen gas concentration in the processing chamber 10 before the generation of steam becomes a sufficiently low value, and it is possible to reliably prevent the detonation reaction from occurring, and furthermore, to surely form the dry oxide film. Can be prevented.
[0069]
【The invention's effect】
According to the present invention, an oxide film or a gate oxide film can be formed essentially in one oxide film forming apparatus, and only one apparatus for forming an oxide film or a gate oxide film is required. The configuration can be simplified. In addition, water vapor can be easily and reliably generated with the oxidation rate suppressed and controlled, and a thin oxide film can be formed by the humidification oxidation method. In addition, since the oxide film is formed by an oxidation method using water vapor, an oxide film having excellent time-dependent dielectric breakdown (TDDB) characteristics can be obtained. In addition, since only the surface of the oxide film is nitrided, there is no adverse effect on the characteristics of the semiconductor element such as a reduction in current driving capability. Further, since the oxide film is nitrided, the p-type impurity reaches the semiconductor layer through the gate oxide film by various heat treatments in a semiconductor device manufacturing process after the formation of the gate electrode, for example, so that the threshold voltage of the PMOS semiconductor element is reduced. A phenomenon such as fluctuation can be reliably avoided.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an oxide film forming apparatus suitable for carrying out a method of the present invention.
FIG. 2 is a schematic partial cross-sectional view of a silicon semiconductor substrate and the like for describing a method of forming an oxide film according to the first embodiment.
FIG. 3 is a schematic view of a cluster tool device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Processing room, 10A ... Plasma generation area, 10B ... Reaction area, 11 ... Stage, 12 ... Heating means, 13 ... Magnet, 14 ... Microwave waveguide, Reference numeral 15: magnetron, 16A, 16B, 16C, 17: gas introduction portion, 18: gas exhaust portion, 20: silicon semiconductor substrate, 21: element isolation region, 22: oxide film (Gate oxide film), 23 gate electrode, 24 sidewall, 25 source / drain region, 26 insulating layer, 27 wiring

Claims (16)

(A) irradiating the hydrogen gas and the oxygen gas with electromagnetic waves to generate steam, oxidizing the surface of the semiconductor layer using the steam, and thereby forming an oxide film on the surface of the semiconductor layer;
(B) a step of nitriding the surface of the oxide film by nitrogen molecules or nitrogen molecule ions in an excited state generated by irradiating a nitrogen-based gas with electromagnetic waves;
Ri consists of,
A method for forming an oxide film, wherein the step (a) and the step (b) are performed in the same processing chamber . (A) irradiating the hydrogen gas and the oxygen gas with electromagnetic waves to generate steam, oxidizing the surface of the semiconductor layer using the steam, and thereby forming an oxide film on the surface of the semiconductor layer;
(B) a step of nitriding the surface of the oxide film by nitrogen molecules or nitrogen molecule ions in an excited state generated by irradiating a nitrogen-based gas with electromagnetic waves;
Consisting of
In the step (a), the temperature of the semiconductor layer when the formation of the oxide film is completed is higher than the temperature of the semiconductor layer when the formation of the oxide film is started. The method for forming an oxide film according to claim 1 or 2 , wherein the electromagnetic waves applied to the hydrogen gas and the oxygen gas are microwaves, and the electromagnetic waves applied to the nitrogen-based gas are also microwaves . 3. The method for forming an oxide film according to claim 1, wherein a heat treatment is performed on the formed oxide film between the steps (a) and (b). The method for forming an oxide film according to claim 4 , wherein the atmosphere of the heat treatment is an inert gas atmosphere containing a halogen element. The method for forming an oxide film according to claim 5 , wherein the halogen element is chlorine. 7. The method according to claim 6 , 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. The method of claim 4 , wherein the heat treatment is performed at a temperature of 700 to 950 ° C. (A) forming a gate oxide film on the surface of the semiconductor layer;
(B) forming a gate electrode made of a silicon layer containing a p-type impurity on the gate oxide film;
A method for manufacturing a p-type semiconductor device comprising:
Step (A) includes:
(A) irradiating the hydrogen gas and the oxygen gas with electromagnetic waves to generate steam, oxidizing the surface of the semiconductor layer using the steam, and thereby forming an oxide film on the surface of the semiconductor layer;
(B) nitriding the surface of the oxide film with nitrogen molecules or nitrogen molecule ions in an excited state generated by irradiating a nitrogen-based gas with an electromagnetic wave, thereby forming a gate oxide film;
Ri consists of,
A method for manufacturing a p-type semiconductor device, wherein the steps (a) and (b) are performed in the same processing chamber . (A) forming a gate oxide film on the surface of the semiconductor layer;
(B) forming a gate electrode made of a silicon layer containing a p-type impurity on the gate oxide film;
A method for manufacturing a p-type semiconductor device comprising:
Step (A) includes:
(A) irradiating the hydrogen gas and the oxygen gas with electromagnetic waves to generate steam, oxidizing the surface of the semiconductor layer using the steam, and thereby forming an oxide film on the surface of the semiconductor layer;
(B) nitriding the surface of the oxide film with nitrogen molecules or nitrogen molecule ions in an excited state generated by irradiating a nitrogen-based gas with an electromagnetic wave, thereby forming a gate oxide film;
Consisting of
A method for manufacturing a p-type semiconductor device, wherein in step (a), the temperature of the semiconductor layer when the formation of the oxide film is completed is higher than the ambient temperature when the formation of the oxide film is started. The method of manufacturing a p-type semiconductor device according to claim 9, wherein the electromagnetic waves applied to the hydrogen gas and the oxygen gas are microwaves, and the electromagnetic waves applied to the nitrogen-based gas are also microwaves . The method for manufacturing a p-type semiconductor device according to claim 9 , wherein a heat treatment is performed on the formed oxide film between step (a) and step (b). The method for manufacturing a p-type semiconductor device according to claim 12 , wherein the atmosphere of the heat treatment is an inert gas atmosphere containing a halogen element. 14. The method according to claim 13 , wherein the halogen element is chlorine. The method according to claim 14 , 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. The method according to claim 12 , wherein the heat treatment is performed at a temperature of 700 to 950 ° C.

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