JP2005252012A - Deposited film forming method, forming method of semiconductor element, semiconductor device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deposited film forming method capable of forming silicon base oxide film uniformly on a substrate to be processed while restraining the plasma damage given to the substrate to be processed or the silicon base oxide film formed on the substrate to be processed. <P>SOLUTION: Mixed gas comprises organic silicon compound gas having silicon atoms, carbon atoms, and oxygen atoms in at least one molecule; oxidizing gas; and rare gas having at least one kind or more among argon, krypton and xenon. The mixed gas is supplied into a plasma processing vessel so that the proportion Pr of the partial pressure of the rare gas becomes 15%≤Pr≤85%. Plasma is generated in the plasma processing vessel to decompose the organic silicon compound gas and the oxidizing gas by the plasma to form the oxide silicon film 22 on the substrate 21 to be processed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film formation method applicable when forming a semiconductor device such as a semiconductor integrated circuit device or a display device such as a liquid crystal display device, and a thin film transistor (TFT) or a metal oxide semiconductor element (MOS), for example. The present invention relates to a method for forming a semiconductor element applicable when forming a semiconductor element such as an element, a semiconductor device having a gate insulating film, and a display device having a semiconductor element such as a pixel switching element.

  In general, in a semiconductor element such as a thin film transistor (hereinafter referred to as TFT), a silicon oxide film is often used as a gate insulating film. As a method for forming a silicon oxide film at a temperature of 600 ° C. or less, a plasma enhanced chemical vapor deposition (CVD) method is known. In a conventionally known plasma CVD method, a silicon oxide film is formed as follows. First, a mixed gas of monosilane gas and oxygen gas is supplied into a chamber provided with a substrate to be processed. Plasma is generated in the chamber. Thereby, monosilane gas and oxygen gas are plasma-discharged, silicon oxide is deposited on the substrate to be processed, and a silicon oxide film is formed. In a top gate type TFT, conventionally, a gate insulating film of 80 to 100 nm is formed by depositing silicon oxide by a plasma CVD method on a semiconductor layer of about 50 nm processed into an island shape.

  By the way, in recent years, TFTs have been required to be downsized while improving the characteristics of the devices with the increase in size and multifunction of display devices, or the development of new display devices such as organic EL display devices. It is coming. As the TFT is miniaturized, it is necessary to reduce the thickness of the gate insulating film. Specifically, in a TFT having a channel length of 1 nm, the gate insulating film is required to be as thin as 30 nm.

  However, in the case of a top gate type TFT in which a gate insulating film is formed on an island-shaped semiconductor layer, the gate insulating film is provided so as to cover the entire area of the semiconductor layer and the step formed by the semiconductor layer. There must be. Therefore, the leakage current of the gate insulating film tends to increase at the step portion of the semiconductor layer. Furthermore, if the gate insulating film is a thin silicon oxide film of 30 nm, the leakage current further increases.

  As described above, in the case of a top gate type TFT having a semiconductor layer formed in an island shape and the gate insulating film is thinned down to about 30 nm, in order to obtain sufficient device characteristics, an oxidation is required. There is a need to improve the step coverage of a silicon film to reduce leakage current.

Tetraethoxysilane (so-called TEOS) is known as a silicon source from which good step coverage can be easily obtained. As a method for forming a silicon oxide film using a TEOS gas, a plasma CVD method using a mixed gas of a TEOS gas, an oxygen gas, and a helium gas has been proposed (see, for example, Non-Patent Document 1).
CP Chang, et al., J. Appl. Phys. 67 (4) (1990) 2119

However, in plasma, there is a high probability that electrons will adhere to oxygen gas, that is, oxygen gas tends to be negative ions. Therefore, in the technique described in Non-Patent Document 1, as the partial pressure of oxygen gas is set higher, more O ₂ ⁻ ions and O ⁻ ions are generated in the plasma, and the uniformity of the plasma is reduced. There is. Also, O ₂ in the plasma ^- ions and O ^- the negative ions, such as ions increases, there is also a problem that the plasma spread in terms of ambipolar diffusion is easily inhibited. For these reasons, with the technique described in Non-Patent Document 1, it may be difficult to obtain a uniform film thickness distribution in the formed silicon oxide film.

  Furthermore, in the technique described in Non-Patent Document 1, helium gas is mixed in the mixed gas. However, helium gas has a very high metastable energy in plasma of 19.8 eV. Therefore, helium gas is not very practical in the plasma CVD method, and there is a problem that plasma damage is likely to occur on the substrate to be processed and the silicon oxide film.

  The present invention has been made based on such a situation, and suppresses plasma damage to the substrate to be processed and the silicon-based oxide film formed on the substrate to be processed, while suppressing the silicon-based oxide film on the substrate to be processed. An object of the present invention is to provide a film forming method, a semiconductor element forming method, a semiconductor device, and a display device.

  The film forming method according to the first aspect of the present invention includes an organic silicon compound gas having at least a silicon atom, a carbon atom, and an oxygen atom in one molecule, an oxidizing gas, argon, krypton, and xenon. Supplying a mixed gas containing one or more rare gases into the plasma processing container such that a ratio Pr of the rare gas partial pressure is 15% ≦ Pr ≦ 85%; and the plasma processing container And forming a silicon oxide film on the substrate to be processed by generating plasma therein to decompose the organic silicon compound gas and the oxidizing gas with plasma.

  The inventors of the present application have found that oxygen radicals generated in the plasma are not reduced in the organic silicon compound gas, the oxidizing gas, and the rare gas mixed gas even if the partial pressure of the oxygen gas is reduced. . This is because oxygen atoms are generated by energy transfer from a rare gas excited in plasma, and oxygen radicals are determined by the product of the rare gas concentration and the oxygen gas concentration. That is, oxygen atoms can be generated most efficiently in the plasma when the ratio Pr of the partial pressure of the rare gas in the mixed gas is around 50% (see FIG. 3).

  It was found that in the region where the ratio Pr of the partial pressure of the rare gas is less than 15%, the concentration of oxygen gas as a raw material for generating oxygen radicals is low, which is not practical. Further, when the ratio Pr of the partial pressure of the rare gas exceeds 85%, not only the negative ions due to oxygen increase in the plasma, but also the partial pressure of the rare gas decreases, so that the oxygen gas is efficiently decomposed into oxygen atoms. It has also been found that this reaction is likely to be inhibited. For these reasons, the inventors of the present application preferably set the ratio Pr of the partial pressure of the rare gas to the total pressure of the mixed gas to 15% ≦ Pr ≦ 85%, and more preferably 20% ≦ Pr. It was found that ≦ 80%.

  Further, the energy required to generate excited oxygen atoms suitable for the oxidation reaction is about 7.0 eV to 11.6 eV. On the other hand, a rare gas takes a metastable state with a long lifetime in plasma, but its energy varies depending on the type of the rare gas.

Helium (He): 19.8 eV
Neon (Ne): 17.0 eV
Argon (Ar): 11.6 eV
Krypton (Kr): 9.9 eV
Xenon (Xe): 8.3 eV
Thus, He and Ne have a relatively large metastable energy, whereas Ar, Kr, or Xe have a relatively small metastable energy. When the metastable energy is large such as He or Ne, the substrate to be processed and the silicon oxide film as the silicon-based oxide film formed on the substrate to be processed are easily damaged during film formation. On the other hand, Ar, Kr, or Xe has an energy close to the energy (7.0 eV to 11.6 eV) necessary for generating an excited oxygen atom suitable for the oxidation reaction. In this case, excited oxygen atoms can be efficiently generated from oxygen molecules while suppressing damage to the substrate to be processed and the silicon oxide film formed on the substrate to be processed.

  As described above, according to the film forming method according to the first aspect of the present invention, the rare gas having at least one of argon (Ar), krypton (Kr), and xenon (Xe) is separated. The pressure ratio Pr is 15% ≦ Pr ≦ 85%, and is present in a mixed gas containing an organic silicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule and an oxidizing gas. ing.

Therefore, oxygen radicals can be generated satisfactorily and oxygen gas can be efficiently decomposed into oxygen molecules. Moreover, since the partial pressure of the O ₂ gas in the mixed gas can be kept low, as a result, the amount of O ₂ ⁻ ions and O ⁻ ions generated in the plasma can be reduced. Thereby, since inhibition of the spread of the plasma by negative ions is suppressed, the plasma can be generated uniformly. Therefore, the silicon oxide film can be uniformly formed on the substrate to be processed.

  Further, as the rare gas, a gas having at least one of Ar, Kr, and Xe having a metastable energy approximate to the energy necessary for generating excited oxygen atoms suitable for the oxidation reaction is used. Therefore, oxygen gas can be efficiently decomposed into oxygen molecules while suppressing plasma damage to the substrate to be processed and the silicon oxide film formed on the substrate to be processed.

  In the film forming method according to the second aspect of the present invention, a mixed gas containing an organic silicon compound gas having at least a silicon atom, a carbon atom, and an oxygen atom in one molecule, an oxidizing gas, and a nitrogen gas, A step of supplying the nitrogen gas partial pressure Pr into the plasma processing vessel so that the ratio Pr is 15% ≦ Pr ≦ 85%; generating plasma in the plasma processing vessel to generate the organosilicon compound gas and the A film forming step of decomposing the oxidizing gas with plasma to form a silicon oxynitride film on the substrate to be processed.

  The inventors of the present application have found that in a mixed gas containing an organic silicon compound, an oxidizing gas, and a nitrogen gas, oxygen radicals generated in the plasma are not reduced even when the partial pressure of the oxygen gas is reduced. . This is because oxygen atoms are generated by energy transfer from nitrogen gas excited in plasma, and oxygen radicals are determined by the product of nitrogen gas concentration and oxygen gas concentration. That is, oxygen atoms can be generated most efficiently in plasma when the ratio Pr of the nitrogen gas in the mixed gas is around 50%.

  It was found that in the region where the ratio of the partial pressure of nitrogen gas is less than 15%, the concentration of oxygen gas as a raw material for generating oxygen radicals is low, which is not very practical. Further, when the ratio Pr of the partial pressure of nitrogen gas exceeds 85%, not only the negative ions due to oxygen increase in the plasma, but also the partial pressure of nitrogen gas decreases, so that the oxygen gas is efficiently decomposed into oxygen atoms. It has also been found that this reaction is likely to be inhibited. For these reasons, the inventors of the present application preferably set the ratio Pr of the partial pressure of nitrogen gas to the total pressure of the mixed gas to 15% ≦ Pr ≦ 85%, more preferably 20% ≦ Pr. It was found that ≦ 80%.

  Further, the metastable energy of nitrogen is 10.3 eV, which is close to the above-described metastable energy of Ar and Kr. That is, it can be expected that an oxygen atom generation effect similar to that of the film forming method according to the first aspect of the present invention can be obtained by replacing the rare gas described above with nitrogen gas. Therefore, it is possible to efficiently generate excited oxygen atoms from oxygen molecules while suppressing damage to the substrate to be processed and the silicon-based oxide film formed on the substrate to be processed during film formation.

Further, when nitrogen gas is used instead of the rare gas, nitrogen atoms can be taken into the film when the silicon-based oxide film is formed. That is, the film structure can be amorphous SiO _X N _Y. Therefore, a silicon oxynitride film as a silicon-based oxide film can be formed on the substrate to be processed.

  As described above, according to the film forming method according to the second aspect of the present invention, nitrogen gas is at least silicon atoms in one molecule so that the partial pressure ratio Pr is 15% ≦ Pr ≦ 85%. , Carbon atoms and oxygen atoms are present in a mixed gas containing an organic silicon compound gas and an oxidizing gas.

Therefore, oxygen radicals can be generated satisfactorily and oxygen gas can be efficiently decomposed into oxygen molecules. Moreover, since the partial pressure of the O ₂ gas in the mixed gas can be kept low, as a result, the amount of O ₂ ⁻ ions and O ⁻ ions generated in the plasma can be reduced. Thereby, since inhibition of the spread of the plasma by negative ions is suppressed, the plasma can be generated uniformly. Therefore, the silicon oxynitride film can be uniformly formed on the substrate to be processed.

  Furthermore, the metastable energy of nitrogen gas is close to the metastable energy of Ar and Kr, that is, close to the energy necessary for generating excited oxygen atoms suitable for the oxidation reaction. Therefore, by mixing nitrogen gas into the mixed gas, oxygen gas can be efficiently decomposed into oxygen molecules while suppressing plasma damage to the substrate to be processed and the silicon oxynitride film formed on the substrate to be processed. it can.

  In the first and second film forming methods according to the present invention, as the “substrate to be processed”, for example, a substrate made of silicon, glass, quartz glass, ceramics, plastic (resin), or the like can be used. . In addition, the “substrate to be processed” is a substrate in which an insulating film, a metal film, a semiconductor layer, or the like is formed on a substrate made of silicon, glass, quartz glass, ceramics, plastic (resin), or the like. An insulating film, a metal film, or a stack of two or more semiconductor layers, or a circuit element or a part of the circuit element formed on the substrate can also be used.

  In the first and second film forming methods according to the present invention, as the organic silicon compound gas, tetraethoxysilane (hereinafter referred to as TEOS), tetramethylcyclotetrasiloxane (hereinafter referred to as TEOS), It is preferable to use a gas containing one or more of TMCTS, diacetoxyditertiarybutoxysilane (hereinafter referred to as DADBS), and hexamethyldisiloxane (hereinafter referred to as HMDSO).

The structural formula of TEOS is shown below.

Since TEOS is easily polarized between O and C, it is oxidized and decomposed by oxygen atoms to form an intermediate product having an OH group that is a polar group.

The structural formulas of TMCTS, DADBS, and HMDSO are shown below.

  Although not shown, TMCTS, DADBS, and HMDSO are also oxidized and decomposed by oxygen to form an intermediate product having a polar OH group.

  These organosilicon compounds are known to be able to significantly increase the surface diffusion coefficient on the surface to be processed (substrate surface) by optimizing the decomposition control in plasma. Yes. That is, these organic silicon compounds can control the decomposition in plasma, thereby reducing the intramolecular ratio of OH groups, which are polar groups, and reducing the adhesion probability on the Si surface. In addition, since these organic silicon compounds and intermediate products generated from these organic silicon compounds are molecules having a relatively large molecular volume, OH groups generated by decomposition reaction in the plasma due to the steric effect are formed on the surface of the Si substrate. It is thought to suppress the interaction. Therefore, each intermediate product generated from these organosilicon compounds can be uniformly attached to the substrate to be processed. The fact that the intermediate product can be uniformly attached to the substrate to be processed means that a silicon-based oxide film can be uniformly formed on the substrate to be processed.

As in the first and second film forming methods of the present invention, a silicon-based oxide film is formed using an organic silicon compound having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule. In some cases, it is preferable to mix oxygen gas into the mixed gas. By mixing oxygen gas into the mixed gas, not only the organic silicon compound is decomposed in plasma, but also the amount of carbon atoms mixed as impurities in the silicon-based oxide film can be reduced. In other words, oxygen gas oxidizes hydrocarbons such as ethylene that are generated when organic silicon compounds are decomposed, converts them into compounds with high vapor pressure, and excludes them from the system. At the same time, carbon incorporated into the silicon-based oxide film It acts to remove carbon atoms from the silicon-based oxide film as a compound such as CO ₂ .

In the film forming methods according to the first and second measures of the present invention, the oxidizing gas may be oxygen (O ₂ ) gas, ozone (O ₃ ) gas, carbon monoxide (CO) gas, carbon dioxide (CO _2). ) Gas, nitrogen monoxide (NO) gas, and gas containing one or more of dinitrogen monoxide gas (N ₂ O) can be used. By using these oxidizing gases, the organic silicon compound can be efficiently oxidized and decomposed.

By the way, the above-mentioned oxidizing gases have different characteristics, so that they may be properly used as desired. When a gas made of a compound having nitrogen atoms is used as the oxidizing gas, the nitrogen atoms are easily localized at the interface between the substrate to be processed and the silicon-based oxide film or the surface of the silicon-based oxide film. Therefore, the interface state density of the silicon-based oxide film is increased. This tendency becomes more prominent as the electron density in the plasma increases. On the other hand, when a gas made of a compound having a carbon atom is used as the oxidizing gas, the influence on the interface state density of the silicon-based oxide film can be suppressed. This is because the organic silicon compound gas has carbon atoms, so even if a gas containing carbon is used as the oxidizing gas, it is considered that the purity of the formed silicon-based oxide film is not so much affected. It is. Further, O ₃ gas has a characteristic that it is easily decomposed and has high reactivity as compared with other oxidizing gases.

  In the first and second film forming methods according to the present invention, when the power supply frequency of the plasma generated in the plasma processing container is less than 1 MHz, ions in the plasma follow, so that stable plasma can be obtained. hard. Moreover, when the power supply frequency of the plasma generated in the plasma processing container exceeds 10 GHz, the plasma processing apparatus tends to be expensive, and is not very suitable for practical use. Therefore, it is preferable that the power supply frequency of the plasma generated in the plasma processing vessel is in the range of a high frequency band of 1 MHz to a microwave band of 10 GHz.

  In the method for forming a semiconductor element according to the third aspect of the present invention, a process substrate having at least a part of a semiconductor is prepared and accommodated in a plasma processing container, and at least silicon atoms and carbon atoms are contained in one molecule. And a mixed gas containing an organic silicon compound gas having oxygen atoms, an oxidizing gas, and a rare gas having at least one of argon, krypton, and xenon, a partial pressure ratio Pr of the rare gas is A step of supplying the plasma processing container so as to satisfy 15% ≦ Pr ≦ 85%; and generating plasma in the plasma processing container to decompose the organosilicon compound gas and the oxidizing gas with the plasma. And a step of forming a silicon oxide film on the semiconductor layer.

  According to the method for forming a semiconductor element according to the third aspect of the present invention, as in the film forming method according to the first aspect of the present invention, the substrate to be processed and the silicon-based oxide film formed on the substrate to be processed The silicon oxide film can be uniformly formed on the semiconductor while suppressing plasma damage to the silicon oxide film.

  In the method for forming a semiconductor element according to the fourth aspect of the present invention, a process substrate having at least a part of a semiconductor is prepared and accommodated in a plasma processing container, and at least silicon atoms and carbon atoms are contained in one molecule. , And an oxygen atom-containing organic silicon compound gas, an oxidizing gas, and a nitrogen gas, and the plasma has a plasma partial pressure ratio Pr of 15% ≦ Pr ≦ 85%. Supplying to the processing container; generating plasma in the plasma processing container to decompose the organic silicon compound gas and the oxidizing gas with plasma; and forming a silicon oxynitride film on the semiconductor layer; ,have.

  According to the method for forming a semiconductor element according to the fourth aspect of the present invention, as in the film forming method according to the second aspect of the present invention, the substrate to be processed and the silicon-based oxide film formed on the substrate to be processed The silicon oxynitride film can be uniformly formed on the semiconductor while suppressing plasma damage to the silicon oxynitride film.

  In the method for forming a semiconductor element according to the third and fourth aspects of the present invention, for example, a silicon substrate can be used as the “substrate to be processed having at least a part of the semiconductor”. In addition, as the “substrate to be processed having at least a part of a semiconductor”, for example, a semiconductor layer formed on at least a part of a substrate made of silicon, glass, quartz glass, ceramics, plastic (resin), or the like, Two or more insulating films, metal films, or semiconductor layers are laminated on at least a part of the substrate, and the semiconductor layer is exposed on the surface, or circuit elements and circuit elements are formed on the substrate. A part of which is formed and the semiconductor layer is exposed on the surface can also be used.

Also, in the method of forming a semiconductor element according to the third and fourth correspondences of the present invention, as in the film formation method according to the first and second correspondences of the present invention, TEOS gas, It is preferable to use a gas containing one or more of TMCTS gas, DADBS gas, or HMDSO gas. As the oxidizing gas, a gas containing one or more of O ₂ gas, O ₃ gas, CO gas, CO ₂ gas, NO gas, and N ₂ O can be used.

  Further, in the method for forming a semiconductor element according to the third and fourth correspondences of the present invention, the plasma generated in the plasma processing chamber is formed as in the film formation methods according to the first and second correspondences of the present invention. The power supply frequency is preferably in a range from a high frequency band of 1 MHz to a microwave band of 10 GHz.

  Further, the silicon oxide film or the silicon oxynitride film formed by the film forming methods according to the first and second aspects of the present invention can be preferably used as a gate insulating film of a transistor included in a semiconductor device.

  As described above, a silicon oxide film or a silicon oxynitride film can be uniformly formed on a substrate to be processed by using the film formation methods according to the first and second aspects of the present invention. That is, by using the film forming method according to the first and second aspects of the present invention, even a stepped portion such as a gate electrode can be covered well (good coverage with respect to the stepped portion). A silicon oxide film or a silicon oxynitride film can be obtained. Therefore, a semiconductor having a transistor with favorable electrical characteristics can be obtained by applying a silicon oxide film or a silicon oxynitride film formed by the film forming method according to the first and second aspects of the present invention to a gate insulating film. A device can be obtained.

  Furthermore, the semiconductor element formed by the method for forming a semiconductor element according to the third and fourth aspects of the present invention can be suitably used as a pixel switching element included in a display device such as a liquid crystal display device.

  As described above, a silicon oxide film or a silicon oxynitride film can be uniformly formed on a semiconductor by using the method for forming a semiconductor element according to the third and fourth aspects of the present invention. That is, by using the semiconductor element forming method according to the third and fourth aspects of the present invention, a semiconductor element having excellent electrical characteristics can be obtained. Therefore, by applying the semiconductor element formed by the semiconductor element forming method according to the third and fourth aspects of the present invention to the pixel switching element, a liquid crystal display device having a good switching operation can be obtained.

  Hereinafter, a first embodiment of the present invention will be described. In the present embodiment, an embodiment of a film forming method of the present invention and an embodiment of a method of forming a semiconductor element of the present invention will be described.

  First, FIG. 1 shows an example of a plasma enhanced chemical vapor deposition system (Plasma Enhanced Chemical Vapor Deposition System) 10 that can be suitably used in carrying out the film forming method and semiconductor element forming method of the present embodiment. A plasma CVD apparatus 10 shown in FIG. 1 is a parallel plate type plasma CVD apparatus, and includes a chamber 11 as a plasma processing container, a pair of electrodes 12 and 13, a high-frequency power supply device 14, a matching unit 15, and the like. .

  The chamber 11 in which the substrate to be processed is accommodated is a vacuum container and is formed so as to be airtight inside. The chamber 11 is provided with a gas introduction part 11a and a gas discharge part 11b. From the gas introduction part 11a, a mixed gas described later is supplied into the chamber 11 as indicated by an arrow A in FIG. The gas exhaust unit 11b is provided with a vacuum exhaust system 16 using a turbo molecular pump or the like. By operating the evacuation system 16, the chamber 11 can be evacuated to a predetermined degree of vacuum.

  The high frequency power supply device 14 for generating plasma is electrically connected to one electrode 12 of a pair of electrodes 12 and 13 corresponding to each other via a matching unit 15 that adjusts a load. The other electrode 13 is used as an electrode for generating plasma and is grounded.

  A stage for supporting the substrate 21 to be processed is provided in the chamber 11. In the plasma CVD apparatus 10 used in this embodiment, the other electrode 13 also serves as a stage. The stage (electrode) 13 is provided with a heating means 17 for heating the substrate 21 to be processed, such as a heater or lamp annealing.

  The plasma CVD apparatus 10 is configured such that plasma is generated in the chamber 11 by operating a high frequency power supply device 14 and supplying high frequency power to one electrode 12 via a matching unit 15.

  Hereinafter, a film forming method and a semiconductor element forming method of this embodiment will be described.

  First, the substrate 21 to be processed is prepared. As the substrate 21 to be processed, various substrates such as a silicon substrate, a glass substrate that can be suitably used when forming a display circuit of a liquid crystal display device, or a plastic substrate can be widely used. In this embodiment, for example, a silicon substrate (silicon wafer) is used.

Next, an organic silicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule, an oxidizing gas, and a rare gas having at least one of argon, krypton, and xenon, In addition, a mixed gas is prepared such that the ratio Pr of the rare gas partial pressure is 15% ≦ Pr ≦ 85%. In this embodiment, for example, TEOS gas is used as the organic silicon compound gas, O ₂ gas is used as the oxidizing gas, and Kr gas is used as the rare gas. Further, the ratio Pr (dilution ratio) of the Kr gas partial pressure when the mixing ratio of the TEOS gas and the oxygen gas in the mixed gas is 1: 5 and the total pressure of the mixed gas is 100% is 50%. . This mixed gas is accommodated in a cylinder (not shown). This cylinder is attached to the plasma CVD apparatus 10 so as to communicate with the inside of the chamber 11 through the gas introduction part 11a.

  The substrate 21 to be processed is carried into the chamber 11 of the plasma CVD apparatus 10 shown in FIG. The evacuation system 16 is operated, and the inside of the chamber 11 is substantially evacuated. Thereafter, the mixed gas is supplied into the chamber 11 through the gas introduction part 11a so that the pressure becomes 230 Pa. Note that the organic silicon compound gas, the oxidizing gas, and the rare gas may be mixed into the chamber 11 by introducing these gases into the chamber 11 so that the partial pressures thereof become predetermined values. good. In that case, the chamber 11 is preferably provided with three gas introduction portions corresponding to the organic silicon compound gas cylinder, the oxidizing gas cylinder, and the rare gas cylinder, respectively.

The heating means 17 is operated to heat the substrate to be processed 21 to 300 ° C., and the substrate to be processed 21 is kept at this substrate temperature. The high frequency power supply device 14 is operated and high frequency power of 500 W and 40 MHz is supplied to one electrode 12 through the matching unit 15. Thereby, plasma is generated in the chamber 11. Since the chamber 11 is rich in Kr gas, energy is transmitted from the Kr excited in the plasma to the oxygen gas, and oxygen atoms are efficiently generated in the chamber 11 (see FIG. 3). With this oxygen atom, silicon oxide is formed, for example, deposited on the surface of the substrate 21 to be processed, and a silicon oxide film (SiO ₂ film) 22 (see FIG. 2) is formed. Thus, film formation on the substrate 21 is completed.

Further, a method of forming a metal-oxide semiconductor element (hereinafter referred to as a MOS element) 20 (see FIG. 2) as a semiconductor element will be described. The SiO ₂ film 22 formed as described above is used as a gate insulating film, and, for example, an aluminum electrode 23 is deposited on the gate insulating film as a gate electrode.

  Further, the source / drain regions are formed separately by ion-implanting impurities at a high concentration in a predetermined position using the gate electrode as a mask, thereby forming the MOS element 20 which is a semiconductor element and also a semiconductor device. Is completed.

Next, the characteristics of the SiO ₂ film formed by the film forming method of this embodiment were evaluated as follows.
First, eight kinds of mixed gases were prepared in which the TEOS / O ₂ mixing ratio was fixed to 1/5 and the mixing ratio of Kr gas was variously changed. By using these mixed gases and forming a SiO ₂ film on a silicon substrate (silicon wafer) having a diameter of 150 mm, eight types of samples were prepared. The SiO ₂ film was formed by the above-described film forming method.

The in-plane film thickness distribution was measured for each of these samples. FIG. 4 shows the measurement results. As shown in FIG. 4, the in-plane film thickness distribution decreases as the Kr gas partial pressure ratio Pr decreases, and when the Kr gas partial pressure ratio Pr becomes less than 15%, the in-plane film thickness distribution is obtained. Exceeded 20%. Usually, an SiO ₂ film having an in-plane film thickness distribution exceeding 20% is considered to be not very practical to be applied to a semiconductor element or the like. From this measurement result, it was found that a SiO ₂ film having a good in-plane film thickness distribution can be obtained by performing film formation using a mixed gas in which the Kr gas partial pressure ratio Pr is 15% or more. .

Next, TEOS / _{O 2} mixing ratio is 1/5, the mixing ratio is 15% of a mixed gas of Kr gas, TEOS / _{O 2} mixing ratio is 1/5, the mixing ratio is 85% of a mixed gas of Kr gas, and Three kinds of mixed gases having a TEOS / O ₂ mixing ratio of 1/5 and a Kr gas mixing ratio of 95% were prepared. Using these mixed gases, three types of samples were prepared by forming a silicon oxide film on a high resistance FZ silicon wafer. The SiO ₂ film was formed by the film forming method described above.

The film structure of each sample was evaluated by FTIR. FIG. 5 shows the measurement results. As shown in FIG. 5, the LO peak position due to absorption of Si—O stretching vibration depends on the mixing ratio of Kr gas. That is, when the Kr partial pressure ratio Pr is 15% to 85%, the LO peak position is 1067 cm ^{−1 to} 1065 cm ⁻¹ , whereas when the Kr partial pressure ratio Pr is 95%, the LO peak position is Shifted to 1061 cm ⁻¹ .

This result suggests that when a mixed gas having a Kr partial pressure ratio Pr exceeding 85% is used, the amount of oxygen in the SiO ₂ film to be formed is insufficient. That is, in a normal SiO ₂ film, the LO peak due to Si—O stretching vibration absorption is around 1070 cm ⁻¹ , and the shift of the LO peak toward the low wavenumber corresponds to the amount of oxygen deficiency in the film. (Reference: YJChabal (Ed.), Fundamental Aspects of Silicon Oxidation, Springer).

Therefore, from the characteristics shown in FIGS. 4 and 5, if a mixed gas is used in which the ratio Pr of the Kr partial pressure is 15% to 85%, the LO peak position of the formed SiO ₂ film is the same as that of a normal SiO ₂ film. Since it is about the same as the LO peak position, it can be inferred that the amount of oxygen in the formed SiO ₂ film is good. In contrast, when the ratio Pr of the partial pressure of Kr is a mixed gas that exceeds 85%, the low-wave number significantly than LO peak position of LO peak position of the SiO ₂ film is usual SiO ₂ film formed It is presumed that the amount of oxygen in the formed SiO ₂ film is insufficient because of shifting to the side.

Furthermore, a plurality of eight kinds of mixed gases were prepared in which the TEOS / O ₂ mixing ratio was fixed to 1/5 and the mixing ratio of Kr gas was variously changed. A plurality of samples were prepared by forming a SiO ₂ film on a silicon substrate (silicon wafer) using these mixed gases. The SiO ₂ film was formed by the above-described film forming method.

For each of these samples, the current-voltage characteristics of the SiO ₂ film were evaluated. The result has a good qualitative correspondence with the above-mentioned FTIR spectrum (see FIG. 5). That is, in a sample formed using a mixed gas in which the Kr gas partial pressure ratio Pr is 85% or less, the electric field strength is 6 MV / cm or more at a current density of 1 × 10 ⁻⁶ A / cm ² , When the electric field strength was 2 MV / cm, the current density was 3 × 10 ⁻¹⁰ A / cm ² or less, indicating good insulating film characteristics. On the other hand, in a sample formed using a mixed gas in which the Kr gas partial pressure ratio Pr is 95%, the current density is 5 × 10 ⁻⁹ A / cm ² when the electric field strength is 2 mv / cm ^2. Increased results. From this measurement result, it was found that a SiO ₂ film having good insulating film characteristics can be obtained by forming a film using a mixed gas in which the Kr gas partial pressure ratio Pr is 85% or less.

  From the above evaluations, a silicon oxide film having a small in-plane distribution of film thickness and excellent withstand voltage and leakage current characteristics by setting the Kr mixing ratio to 15% to 85%, more preferably 20% to 80%. I found out that The inventors of the present application have confirmed that this effect can be obtained not only in the case where the power supply frequency is 40 MHz, but also in the microwave band from 1.6 MHz to 2.45 GHz. It was.

  As described above, according to the film forming method and the semiconductor element forming method of the present embodiment, Kr gas as a rare gas having at least one of Ar, Kr, and Xe is divided into a partial pressure ratio Pr. Is a mixed gas containing TEOS gas as an organic silicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule and oxygen gas as an oxidizing gas, so that the ratio is 15% ≦ Pr ≦ 85% Exist inside. Therefore, the silicon oxide film 22 can be uniformly formed on the target substrate 21 while suppressing plasma damage to the target substrate 21 and the silicon oxide film 22 formed on the target substrate 21.

  Hereinafter, a second embodiment of the present invention will be described. In this embodiment, an example of a method for forming a top gate TFT as a semiconductor element using the film formation method described in the first embodiment will be described.

FIG. 6 shows an example of a top gate type TFT 30 as a semiconductor element and a semiconductor device. In FIG. 6, reference numeral 31 denotes an insulating substrate such as a glass base, reference numeral 32 denotes a buffer layer made of SiO ₂ provided on the glass base 31, reference numeral 33 denotes a semiconductor layer, and reference numeral 34 denotes an impurity introduced at a high concentration. Ion-implanted source region, symbol 35 is a drain region into which impurities are introduced at a high concentration, for example, ion-implanted drain region, symbol 36 is a channel region, symbol 37 is a gate insulating film made of SiO ₂ formed by the above film formation method, symbol Reference numeral 38 denotes a gate electrode made of Al, reference numeral 39 denotes an interlayer insulating film made of SiO ₂ , reference numeral 40 denotes a source electrode, and reference numeral 41 denotes a drain electrode.

Hereinafter, a method for forming the TFT 30 will be described. First, an SiO ₂ film as the buffer layer 32 is formed on substantially the entire surface on one surface of the base 31. An amorphous silicon (α-Si) layer is formed on the buffer layer 32 by, for example, a low pressure CVD method. Dehydrogenation is performed in a nitrogen gas atmosphere. Thereafter, the α-Si layer is crystallized by laser annealing using an excimer laser. Thereby, a semiconductor layer 33 made of a polycrystalline silicon layer is formed. In the present embodiment, this state is the substrate 50 to be processed. In other words, the substrate to be processed 50 includes a base 31, a buffer layer 32 formed on the base 31, and a plurality of semiconductor layers 33 formed side by side on the buffer layer 32.

  In the case where a plurality of TFTs 30 are formed side by side, such as in a liquid crystal display device, a resist film, which is a photosensitive resin, is applied to the polycrystalline silicon layer by spin coating or the like, and is performed by a photolithography process. A plurality of semiconductor layers 33 can be formed simultaneously by exposing and developing a resist film.

A gate insulating film 37 made of SiO ₂ is formed so as to cover the island-shaped semiconductor layer 33. The gate insulating film 37 can be formed by the film forming method described in the first embodiment. A metal film (for example, an Al film) to be a plurality of gate electrodes 38 is formed on the gate insulating film 37 by a sputtering method or the like.

  In the case where a plurality of TFTs 30 for driving a display device such as a liquid crystal display device are formed side by side as switching elements for pixel selection of the liquid crystal display device, a photolithography method and an etching method are used. A plurality of gate electrodes 38 may be simultaneously formed above each semiconductor layer 33.

  The semiconductor layer 33 is doped with an impurity such as phosphorus (P) at a high concentration by ion implantation or the like. As a result, a source region 34 and a drain region 35 are formed, and a channel region 36 into which no impurity is introduced is formed.

SiO ₂ is deposited so as to cover the gate electrode 38 by plasma CVD, and heat treatment is performed at 600 ° C. Thereby, an interlayer insulating film 39 is formed. Contact holes 42 and 43 corresponding to the source region 34 and the drain region 35 are formed by photolithography and etching. A source electrode 40 is formed so as to be connected to the source region 34 through the contact hole 42. A drain electrode 41 is formed so as to be connected to the drain region 35 through the contact hole 43. Thus, the formation of the TFT 30 as the semiconductor element is completed.

  The TFT 30 can be suitably used as a switching element included in a display device, for example, the liquid crystal display device 100.

  6 and 7 show an example of the active matrix type liquid crystal display device 100. FIG. The liquid crystal display device 100 includes a pair of transparent substrates 101 and 31 as a pair of substrates, a liquid crystal layer 102, a pixel electrode 106, a scanning wiring 107, a signal wiring 108, a counter electrode 109, a plurality of TFTs 30, a scanning line driving circuit 111, A signal line driver circuit 112, a liquid crystal controller 113, and the like are provided.

  For example, a pair of glass plates can be used as the pair of transparent substrates 101 and 31. These bases 101 and 31 are joined via a frame-shaped sealing material (not shown). The liquid crystal layer 102 (see FIG. 6) is provided in a region surrounded by the sealing material between the pair of transparent substrates 101 and 31.

  On the inner surface of one of the pair of transparent substrates 101 and 31, for example, the rear transparent substrate 31, a plurality of buffer layers 32 (see FIG. 6) are provided in a matrix in the row and column directions. A pixel electrode 106 (see FIG. 7), a plurality of TFTs 30 electrically connected to the plurality of pixel electrodes 106, a scanning wiring 107 (see FIG. 7) electrically connected to the plurality of TFTs 30, and a plurality of TFTs 30 An electrically connected signal wiring 108 (see FIG. 7) and the like are provided.

  The scanning wiring 107 is provided along the row direction (horizontal direction in FIG. 7). One ends of these scanning wirings 107 are electrically connected to the scanning line driving circuit 111. For example, the scanning wiring 107 is formed integrally with the gate electrode 38 included in the TFT 30. On the other hand, the signal wiring 108 is provided along the column direction of the pixel electrode 106 (vertical direction in FIG. 7). One ends of these signal wirings 108 are electrically connected to the signal line driver circuit 112. For example, the signal wiring 108 is formed integrally with the drain electrode 41 included in the TFT 30.

  The scanning line driving circuit 111 and the signal line driving circuit 112 are connected to the liquid crystal controller 113. The liquid crystal controller 113 receives, for example, an image signal and a synchronization signal supplied from the outside, and generates a pixel video signal Vpix, a vertical scanning control signal YCT, and a horizontal scanning control signal XCT.

  On the inner surface of the transparent substrate 101 on the front side (upper side in FIG. 6) which is the other transparent substrate, a single film-like transparent counter electrode 109 facing the plurality of pixel electrodes 106 is provided. The counter electrode 109 is made of a transparent electrode such as ITO. In addition, a color filter may be provided on the inner surface of the front transparent substrate 101 or the inner surface of the rear transparent substrate 31 so as to correspond to the plurality of pixel regions in which the plurality of pixel electrodes 106 and the counter electrode 109 face each other, or A light-shielding film may be provided corresponding to the area between the pixel areas.

  A polarizing plate (not shown) is provided outside the pair of transparent substrates 101 and 31. When the liquid crystal display device 100 is a transmissive type, a backlight (not shown) is provided behind the transparent substrate 31 on the rear side. Note that the liquid crystal display device 100 may be of a reflective type or a transflective type. Furthermore, the display device is not limited to a liquid crystal display device, and may be an organic EL or an inorganic EL display device.

The characteristics of the gate insulating film (SiO ₂ film) 37 formed by the film forming method of this embodiment were evaluated as follows.
First, a mixed gas having a TEOS / O ₂ mixing ratio of 1/5 and a Kr gas mixing ratio of 50% was prepared. A PE-CVD film (SiO ₂ film) having a film thickness of 30 nm using the mixed gas on a substrate to be processed on which a first TEG corresponding to 1000 TFTs each having a width of 1 μm, that is, a TFT pattern corresponding to 1000 pieces, is formed. A TEG with a formed was formed. The method for forming the PE-CVD film was performed under the same conditions as the film forming methods of the first and second embodiments. In contrast, a second TEG corresponding to 1000 TFTs each having a width of 1 μm, that is, a TEG in which a thermal oxide film is formed by dry oxidation at 950 ° C. on a substrate to be processed on which 1000 TFT patterns are formed. did.

  For these TEGs, current-electric field characteristics were measured. FIG. 8 shows the measurement results. In general, it is known that a thermal oxide film is an insulating film having a small leakage current and excellent current-electric field characteristics. That is, from the results shown in FIG. 8, the PE-CVD film formed by the film forming method of the first and second embodiments has the same current-electric field characteristics as the thermal oxide film having excellent current-electric field characteristics. It was found to be an insulating film.

Next, eight kinds of mixed gases were prepared in which the TEOS / O ₂ mixing ratio was fixed to 1/5 and the mixing ratio of Kr gas was variously changed. Using these mixed gases, a SiO ₂ film having a thickness of 30 nm was formed on a substrate having a step of 200 nm, and the cross-sectional shape thereof was observed with a transmission electron microscope (TEM) and a scanning electron microscope (SEM). .

It was found that when the Kr ratio is changed, the formation rate of the SiO ₂ film changes, but the coverage of the stepped portion is not affected so much and good coverage characteristics can be obtained. FIG. 9 shows a cross-sectional TEM image when the Kr mixing ratio is 50%, and FIG. 10 shows a cross-sectional SEM image when the Kr mixing ratio is 50%. 9 and 10, when normalized by the film thickness of the lower flat part, the film thickness is 1.08 times maximum at the upper flat part of the step part and 0.80 times minimum at the side wall part, and good coverage is obtained. It turns out that it is obtained. From this result, it was found that the PE-CVD film formed by the film forming methods of the first and second embodiments can be suitably used as a gate insulating film covering the island-shaped semiconductor layer.

  As described above, according to the film forming method of the first embodiment described above, good coverage can be obtained at the stepped portion regardless of the size of the substrate. Therefore, a film with good coverage can be uniformly formed in a large area even for a large substrate applied to a large liquid crystal display device.

  In addition, according to the method for forming a semiconductor element of this embodiment (the method for forming the TFT 30), the gate insulating film 37 with good step coverage can be obtained. That is, a TFT having good coverage (small leakage current) in the vicinity of the semiconductor layer 33, that is, in the stepped portion can be obtained.

  Hereinafter, a third embodiment of the present invention will be described. In the present embodiment, an embodiment of the film forming method of the present invention will be described.

  First, a substrate to be processed is prepared. As the substrate to be processed, various substrates such as a silicon substrate, a glass substrate that can be suitably used for forming a display circuit of a liquid crystal display device, or a plastic substrate can be widely used. In this embodiment, for example, a silicon substrate (silicon wafer) is used.

Next, an organic silicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule, an oxidizing gas, and a nitrogen gas, and the ratio Pr of the partial pressure of the nitrogen gas is 15% ≦ A mixed gas is prepared so that Pr ≦ 85%. In this embodiment, for example, TEOS gas is used as the organic silicon compound gas, and O ₂ gas is used as the oxidizing gas. Further, the ratio Pr (dilution rate) of the partial pressure of N ₂ gas when the mixing ratio of TEOS gas and oxygen gas in the mixed gas is 1: 5 and the total pressure of the mixed gas is 100% is 50%. . This mixed gas is accommodated in a cylinder (not shown). This cylinder is attached to the plasma CVD apparatus 10 so as to communicate with the inside of the chamber 11 through the gas introduction part 11a.

  The substrate to be processed is carried into the chamber 11 of the plasma CVD apparatus 10 shown in FIG. Thereafter, the mixed gas is supplied into the chamber 11 through the gas introduction part 11a so that the pressure becomes 180 Pa. The organic silicon compound gas, the oxidizing gas, and the nitrogen gas may be mixed into the chamber 11 by introducing these gases into the chamber 11 so that each partial pressure becomes a predetermined value. . In that case, the chamber 11 is preferably provided with three gas introduction portions corresponding to the organic silicon compound gas cylinder, the oxidizing gas cylinder, and the nitrogen gas cylinder, respectively.

The heating means 17 is operated to heat the substrate to be processed to 300 ° C., and the substrate to be processed 21 is kept at this substrate temperature. The high frequency power supply device 14 is operated and high frequency power of 500 W and 40 MHz is supplied to one electrode 12 through the matching unit 15. Thereby, plasma is generated in the chamber 11. Since the chamber 11 N ₂ gas is rich, the energy is transmitted from the N ₂ excited by plasma into O ₂ gas, efficiently oxygen atom is generated in the chamber 11. Thereby, silicon oxide is deposited on the surface of the substrate to be processed. Also within the chamber 11, since N ₂ gas is rich, N atom arising from the N ₂ gas is taken into the oxide in silicon. As a result, a silicon oxynitride film (a-SiON film) is formed on the substrate to be processed. Thus, film formation on the substrate to be processed is completed. Although overlapping explanation is omitted, this film forming method is similarly applied when forming a semiconductor element such as the MOS element described in the first embodiment or the TFT described in the second embodiment. can do.

The characteristics of the a-SiO: N film formed by the film forming method of this embodiment were evaluated by secondary ion mass spectrometry (see FIG. 11). As a result, it was confirmed that an a-SiO: N film containing 2 × 10 ²⁰ / cm ³ N atoms was formed on the substrate to be processed. It was also found that the amount of nitrogen atoms in the film thickness direction can be controlled by controlling the amount of nitrogen dilution (Pr) in the plasma.

  Further, although not shown, this a-SiO: N film was formed on a silicon step, and the cross-sectional shape was observed with a TEM. From this TEM photograph, it was found that good coverage of 0.08 or more was obtained at the side wall.

As described above, according to the film formation method and the semiconductor element formation method of the present embodiment, N ₂ gas is at least contained in one molecule so that the partial pressure ratio Pr is 15% ≦ Pr ≦ 85%. It exists in the mixed gas containing TEOS gas as an organic silicon compound gas which has a silicon atom, a carbon atom, and an oxygen atom, and oxygen gas as an oxidizing gas. Therefore, the silicon oxynitride film can be uniformly formed on the target substrate while suppressing plasma damage to the target substrate and the silicon oxynitride film formed on the target substrate.

  The film forming method and the semiconductor element forming method of the present invention are not limited to the first to third embodiments, and can be variously changed without departing from the scope of the invention. . In this embodiment, the MOS element formation method and the top gate TFT formation method have been described as examples of the semiconductor element formation method. However, the semiconductor element formation method of the present invention is limited to the MOS element and the top gate TFT. In addition, the present invention can be widely applied when a silicon insulating film (a silicon oxide film or a silicon oxynitride film) is provided in a semiconductor element, a display device, or the like.

  The film forming method of the present invention can be suitably used for forming a display device such as a semiconductor element or a liquid crystal display device applied to a semiconductor integrated circuit device, for example. Further, the method for forming a semiconductor element of the present invention can be suitably used for forming a semiconductor element such as a thin film transistor (TFT). Furthermore, the film formation method of the present invention can be suitably used when forming a gate insulating film or the like of a transistor included in a semiconductor device. Moreover, the method for forming a semiconductor element of the present invention can be suitably used for forming a display device including a TFT such as a liquid crystal display device or an organic or inorganic EL display device. As a method for forming an insulating film used in the manufacturing process of these semiconductor elements and devices, an insulating film with high coverage and low leakage current can be obtained.

Sectional drawing which shows an example of a plasma CVD apparatus. 1 is a cross-sectional view showing a silicon oxide film formed by using a film forming method according to a first embodiment of the present invention and a MOS element formed by using a method for forming a semiconductor element. Kr / (Kr + _{O 2)} and shows the relationship between the oxygen atom production rate. _{Kr / (Kr + O 2 +} TEOS) and shows the relationship between the in-plane film thickness distribution of the silicon oxide film. Kr _/ a _{(Kr + O 2 + TEOS)} 15%, 85%, shows the infrared absorption spectrum of the silicon oxide film when 95%. Sectional drawing which shows a liquid crystal display device provided with TFT formed using the formation method of the silicon oxide film and semiconductor element which were formed using the film-forming method concerning the 2nd Embodiment of this invention. The top view which shows the liquid crystal display device of FIG. The figure which shows the relationship between the electric field and electric current in TEG equivalent to 1000 TFT level | step differences. 4 is a TEM photograph showing a cross section of a silicon oxide film formed by using a film forming method according to a second embodiment of the present invention. 5 is an SEM photograph showing a cross section of a silicon oxide film formed by using a film forming method according to a second embodiment of the present invention. The figure which shows the measurement result of the element amount in the film | membrane of the silicon oxynitride film | membrane formed using the film-forming method concerning the 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Plasma CVD apparatus, 11 ... Chamber (plasma processing container), 20 ... MOS element, 21 ... Substrate to be processed, 30 ... TFT (semiconductor element), 50 ... Substrate to be processed

Claims (9)

A mixed gas containing an organosilicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule, an oxidizing gas, and a rare gas having at least one of argon, krypton, and xenon, Supplying the rare gas partial pressure ratio Pr into the plasma processing chamber such that 15% ≦ Pr ≦ 85%;
Forming a silicon oxide film on the substrate to be processed by generating plasma in the plasma processing container to decompose the organic silicon compound gas and the oxidizing gas with the plasma. A characteristic film forming method. When a mixed gas containing an organosilicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule, an oxidizing gas, and a nitrogen gas is used, the nitrogen gas partial pressure ratio Pr is 15% ≦ Pr. Supplying into the plasma processing container so that ≦ 85%;
And a film forming step of generating a plasma in the plasma processing container to decompose the organic silicon compound gas and the oxidizing gas with the plasma to form a silicon oxynitride film on the substrate to be processed. A film forming method characterized by the above.   The said organic silicon compound gas is a gas containing one or more of tetraethoxysilane, tetramethylcyclotetrasiloxane, diacetoxyditertiary butoxysilane, and hexamethyldisiloxane. The film forming method.   The oxidizing gas is a gas containing one or more of oxygen gas, ozone gas, carbon monoxide gas, carbon dioxide gas, nitrogen monoxide, and nitrous oxide gas. The film-forming method of any one of these.   The film forming step includes a step of applying a high frequency for generating plasma to the gas, and the power source frequency of the plasma generated in the plasma processing vessel is between a high frequency band of 1 MHz and a microwave band of 10 GHz. The film forming method according to claim 1, wherein the film forming method is any one of the above. Preparing a substrate to be processed having a semiconductor at least in part and storing it in a plasma processing vessel;
A mixed gas containing an organosilicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule, an oxidizing gas, and a rare gas having at least one of argon, krypton, and xenon, Supplying the rare gas partial pressure ratio Pr into the plasma processing chamber so that the ratio Pr is 15% ≦ Pr ≦ 85%;
Generating plasma in the plasma processing vessel to decompose the organic silicon compound gas and the oxidizing gas with plasma to form a silicon oxide film on the semiconductor layer. A method for forming a semiconductor element. Preparing a substrate to be processed having a semiconductor at least in part and storing it in a plasma processing vessel;
When a mixed gas containing an organosilicon compound gas having at least silicon atoms, carbon atoms, and oxygen atoms in one molecule, an oxidizing gas, and a nitrogen gas is used, the nitrogen gas partial pressure ratio Pr is 15% ≦ Pr. Supplying the plasma processing vessel so that ≦ 85%;
Generating plasma in the plasma processing vessel to decompose the organic silicon compound gas and the oxidizing gas with plasma to form a silicon oxynitride film on the semiconductor layer. A method for forming a semiconductor element.   A semiconductor device comprising a transistor using a silicon oxide film or a silicon oxynitride film formed by the film formation method according to claim 1 as a gate insulating film.   8. A display device using a semiconductor element formed by the method for forming a semiconductor element according to claim 6 as a pixel switching element.

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