JPH08340056A - Formation of silicon insulating film and semiconductor device - Google Patents

Abstract

PURPOSE: To control the desired stress leak current resistance of a silicon insulating film by controlling the concentration of nitrogen introduced to a silicon oxide film by nitriding the silicon oxide film in a nitrogen oxide atmosphere after the silicon oxide film is formed on a silicon substrate. CONSTITUTION: A silicon oxide film 12 is formed on the surface of a semiconductor substrate 10 composed of a P-type silicon substrate by using a humidifying oxidizing method. After the film 12 is formed, a silicon insulating film 13 is formed by oxidizing and nitriding the film 12 in an oxygen gas atmosphere and a gate electrode 14 composed of N-type polysilicon containing diffused phosphorus is formed on the film 13 by using a CVD technique. Therefore, the desired stress leak current resistance of the film 13 can be improved, because the resistance can be controlled by controlling the concentration of the nitrogen introduced to the film 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a silicon-based insulating film containing at least nitrogen and oxygen. More specifically, desired stress leak current resistance is controlled by the concentration of nitrogen introduced into the film. And a method for forming a silicon-based insulating film.

[0002]

2. Description of the Related Art In a floating gate type flash memory, writing / erasing is performed by injecting or releasing charges in a floating gate. Although various charge injection methods have been proposed, a channel hot electron injection method or a Fowler-Nordheim (FN) tunnel current is generated by applying a high electric field to a tunnel oxide film (also referred to as a gate insulating film). The method of flowing and injecting or releasing electrons is common.

As described above, in the flash memory, a current flows through the tunnel oxide film (that is, electrons pass through) every time writing / erasing occurs, so that a trap level is newly generated in the tunnel oxide film and a low electric field is eventually generated. Even if the voltage is applied, the leak current easily flows. This is called a stress leak current, and it occurs remarkably as the oxide film becomes thinner (reference: IEEE Tech. Dig. Of IEDM 1988,
424 to 427), it is known that the characteristics of flash memory are deteriorated (reference: IEEE Tech. Dig.
of IEDM 1990, pp. 111-114).

That is, in the flash memory, it is required that the tunnel oxide film be thinned as well as highly integrated, but the stress leak current becomes remarkable with it, so that the generation of traps is suppressed even when the charge is injected. Thin (1
The development of a tunnel oxide film is an urgent matter.

Conventionally, as a method of suppressing this stress leak current, a silicon oxynitriding method (reference: Exteded Abs
t. of SSDM 1994, pp. 859-861, Ultra Low Moisture Oxidation Method (Monthly Semiconductor World 1993.1 117)
~ 122), hydrogen radical water oxidation method (Semiconductor / Integrated Circuit Symposium Proceedings 1993.12, 128-)
(Page 133) and the like are reported. Among them, many reports have been made on the silicon oxynitride film as a relatively easy suppression method, and as an atmosphere during the nitriding treatment, dinitrogen monoxide (N ₂ O) (reference: Exteded Abst. Of SSDM 1994, (Pp. 859-861) and nitric oxide (NO) (Reference: Ext
eded Abst. of SSDM 1994, pp. 862-864).

[0006]

Among the malfunctions of the flash memory caused by the traps in the tunnel oxide film as described above, the biggest problem is the stress leak current.
And, as described above, the technique of using a silicon oxynitride film to suppress it is known. However, the conventional reports do not clarify how much nitrogen must be introduced into the oxide film in order to avoid the malfunction of the flash memory caused by the stress leak current. That is, a stress leak current is significantly generated in 5 to 10 n
In the film thickness of m, the correlation between the amount of nitrogen introduced into the oxide film and the stress leak current suppressing effect (resistance) is unclear.

The present invention has been made in view of the above circumstances, and can improve the resistance to stress leak current without deteriorating the transistor characteristics, and is particularly suitable for use as a gate insulating film of a nonvolatile semiconductor memory device. An object is to provide a method for forming a silicon-based insulating film.

[0008]

In order to overcome the above-mentioned problems, the method for forming a silicon-based insulating film according to the present invention comprises forming a silicon oxide film and then nitriding the silicon oxide film in a nitrogen oxide atmosphere. Thus, the desired stress leak current resistance is controlled by the concentration of nitrogen introduced into the film.

The concentration of nitrogen introduced into the silicon oxide film or near the interface between the silicon oxide film and the silicon substrate by the nitriding treatment is 1 × 10 ²⁰ atoms / c.
It is preferably m ³ or more. The concentration of hydrogen introduced into the silicon oxide film or near the interface between the silicon oxide film and the silicon substrate by the nitriding treatment is 5 × 10 ^20.
It is preferably atoms / cm ³ or less.

The nitric oxide atmosphere contains nitric oxide (N
O), nitrogen dioxide (NO ₂ ), or nitrous oxide (N
It is preferable that the atmosphere contains a gas in the form of ₂ O). The nitriding treatment is preferably performed in a temperature range of 800 to 1200 ° C.

The nitriding treatment is preferably heated by infrared irradiation. The film thickness of the silicon-based insulating film after the nitriding treatment is preferably in the range of 5 to 10 nm. The method for forming the silicon oxide film is preferably a wet oxidation method.

A semiconductor device according to the present invention has an insulating film formed by using the above-described method for forming a silicon-based insulating film. In the nonvolatile semiconductor memory device according to the present invention, the gate insulating film between the floating gate and the silicon substrate is formed using the above-described method for forming a silicon-based insulating film.

[0013]

In the method of forming a silicon-based insulating film according to the present invention, by nitriding the silicon oxide film,
Nitrogen is introduced into the oxide film and near the interface between the oxide film and the silicon substrate. As a result of the introduction of nitrogen, the dangling bond of Si or O, which is considered to be the cause of the trapping unit, can be terminated with nitrogen, and the stress leak current resistance can be improved.

Further, in the present invention, the concentration of nitrogen introduced into the oxide film and near the interface between the oxide film and the silicon substrate is controlled by controlling the temperature and time for nitriding the silicon oxide film. Then, by determining the correlation between the stress leak current and the nitrogen concentration, the nitrogen concentration required to obtain the desired stress leak current resistance is clarified. When the concentration of introduced nitrogen is high, the stress leak current resistance is high, but the transconductance (g
It has been reported that the characteristics of the MOS transistor such as m) are deteriorated. Therefore, it is necessary to control the concentration of nitrogen contained in the silicon oxide film in order to maintain the stress leak current resistance at a high level and not to deteriorate the transistor characteristics. In the present invention, by controlling the concentration of nitrogen introduced into the film, it is possible to improve the stress leak current resistance without deteriorating the transistor characteristics.

Further, in the present invention, when a gas in the form of nitric oxide (NO), nitrogen dioxide (NO ₂ ) or dinitrogen monoxide (N ₂ O) is used as the nitriding atmosphere,
Hydrogen can be prevented from being mixed into the film during the nitriding treatment. For example, when the silicon oxide film is nitrided using NH ₃ , hydrogen is introduced into the film at the same time as nitrogen, and the stress leak current resistance deteriorates. Prevention of hydrogen contamination is an important issue. That is, in the present invention, when a gas in the form of nitric oxide (NO), nitrogen dioxide (NO ₂ ) or dinitrogen monoxide (N ₂ O) is used as the nitriding atmosphere, the obtained silicon-based insulation is obtained. The resistance of the film to stress leak current is improved.

Furthermore, in the present invention, when the silicon oxide film is formed by the wet oxidation method, the stress leak current resistance of the finally obtained silicon-based insulating film is further improved. This is because, when comparing the silicon oxide film itself before the nitriding treatment, the silicon oxide film formed by the wet oxidation method has higher stress leak current resistance than the silicon oxide film formed by the dry oxidation method.

In the present invention, the concentration of nitrogen introduced into the film or near the interface between the film and the silicon substrate is 1 × 1.
The reason why it is preferably 0 ²⁰ atoms / cm ³ or higher is that the effect of improving the stress leak current resistance is low at a concentration lower than this. In the present invention, it is preferable that the concentration of hydrogen introduced into the film or in the vicinity of the interface between the film and the silicon substrate is 5 × 10 ²⁰ atoms / cm ³ or less because of stress caused by electron trap caused by hydrogen superposition. This is to suppress the leak current.

In the present invention, the heat treatment temperature during the nitriding treatment is preferably carried out within a temperature range of 800 to 1200 ° C. because nitrogen tends to be hard to occur at 800 ° C. or lower.

[0019]

EXAMPLES A method for forming a silicon-based insulating film according to the present invention will be described below based on examples. In the following description, in Example 1, the nitrogen concentration required to obtain the desired stress leak current resistance is clarified. Comparative Example 1 is an example using a silicon oxide film that is not nitrided, and Comparative Example 2 is an example using a silicon oxynitride film in which hydrogen is mixed with nitrogen during the nitriding treatment, both of which are stress leak current resistant. Is an example for comparing with Example 1. (Example 1) A silicon oxide film 12 was formed on the surface of a semiconductor substrate 10 made of a P-type silicon substrate shown in FIG. 1A by a pyrogenic oxidation method which is a kind of humidification oxidation method. The conditions of the pyrogenic oxidation method can be as follows, for example.

Substrate temperature: 850 ° C. If necessary, before the silicon oxide film is formed, the surface of the semiconductor substrate is cleaned (cleaning with chemicals or pure water, natural treatment by heat treatment in a reducing gas atmosphere). Removal of oxide film, etc.)
I do.

Next, this silicon oxide film was subjected to an oxynitriding treatment in an N ₂ O gas atmosphere (see FIG. 1B). An infrared irradiation device was used for this oxynitriding treatment, but the temperature and time of the treatment were changed as follows in order to control the amount of nitrogen introduced into the oxide film.

[0022]

[Table 1] (a): 800 ° C x 20 seconds (b): 800 ° C x 60 seconds (c): 900 ° C x 20 seconds (d): 900 ° C x 60 seconds (e): 1000 ° C × 20 seconds (f): 1000 ° C. × 60 seconds After that, by using known CVD technology, photolithography technology, and dry etching technology, N-type in which phosphorus (P) is diffused on the silicon-based insulating film 13 The gate electrode 14 made of polysilicon was formed (see FIG. 1C). Thus, a so-called MOS capacitor was formed.

The films obtained under the conditions (a) to (f) in Table 1 above have different film thicknesses after oxynitriding treatment due to the difference in processing temperature and time. However, by controlling the thickness of the silicon oxide film before the treatment for each oxynitriding treatment condition,
The film thickness obtained from the capacitance of the MOS capacitor is 6.
It falls within the range of 5 to 6.8 nm, and it is considered that the influence of the film thickness difference is small. Comparative Example 1 Comparative Example 1 is different from Example 1 in that the nitriding treatment was not performed. That is, in Comparative Example 1, a 6.5 nm-thickness silicon oxide film was formed on the surface of a semiconductor substrate made of a P-type silicon substrate by a conventional pyrogenic oxidation method which is a kind of humidification oxidation method. The conditions for pyrogenic oxidation were the same as in Example 1.

After that, a gate electrode made of N-type polysilicon in which phosphorus (P) was diffused was formed on the silicon oxide film by using the known CVD technique, photolithography technique and dry etching technique. Thus, a so-called MOS capacitor was formed. Comparative Example 2 Comparative Example 2 is different from Example 1 in that the nitriding treatment was performed in an ammonia (NH ₃ ) atmosphere before the oxynitriding treatment was performed in an N ₂ O gas atmosphere. That is, in Comparative Example 2, first, a silicon oxide film was formed on the surface of a semiconductor substrate made of a P-type silicon substrate by a conventional pyrogenic oxidation method which is a kind of humidification oxidation method. The conditions for pyrogenic oxidation were the same as in Example 1.

Next, this silicon oxide film was nitrided in an NH ₃ gas atmosphere. When NH ₃ is used, a high concentration of nitrogen can be introduced, but hydrogen is also introduced at the same time. Finally, in order to diffuse the hydrogen out of the oxide film, an oxynitriding treatment was performed in an N ₂ O gas atmosphere. At this time, the temperatures of the NH ₃ nitriding treatment and the N ₂ O oxynitriding treatment were changed as follows (both time was 60 seconds).

[0026]

[Table 2] (g): NH ₃ (800 ° C) + N ₂ O (900 ° C) (h): NH ₃ (900 ° C) + N ₂ O (900 ° C) Then, the known CVD technique, photo A gate electrode made of N-type polysilicon in which phosphorus (P) was diffused was formed on the silicon-based insulating film by using the lithography technique and the dry etching technique. Thus, so-called MOS
A capacitor was formed. (Stress Leakage Current) A circuit schematically shown in FIG. 2 was prepared, and the stress leakage current of the MOS capacitors according to Example 1 and Comparative Examples 1 and 2 was measured by the following procedure.

(1) First, before applying stress, a voltage is applied to the silicon-based insulating film 13 to detect the flowing current,
So-called current-voltage characteristics were measured. (2) Next, constant current stress was applied to the silicon-based insulating film 13 to inject 5 C / cm ² of electrons. At this time, the constant current density was 100 mA / cm ² , and this was kept flowing for 50 seconds.

(3) Finally, the current after applying the stress
The voltage characteristic was measured again. The silicon substrate 1 used
Since 0 is a P-type, a negative voltage is applied to the gate electrode 14 when current / voltage characteristics and constant current stress are applied, and electrons are injected from the gate electrode 14 into the silicon-based insulating film 13. In addition, the silicon-based insulating film 13 used for the measurement
The area of the gate electrode 14 on the substrate was 150 × 150 μm ² , and 5 MOS capacitors were measured per semiconductor substrate 10.

FIG. 3 shows Example 1 (f) ((f) in Table 1)
Example 1 using a film thermally nitrided under the conditions of 1) and Comparative Example 1
The current-voltage characteristics before and after the stress application are shown. The horizontal axis represents the electric field obtained by normalizing the voltage applied to the gate electrode 14 by the film thickness, and the vertical axis represents the current density obtained by normalizing the current flowing through the oxide film by the area of the gate electrode 14. About -8 MV / c
The stress leak current is the current that increases after applying stress under an electric field of m or less. Then, the value is the first embodiment.
(F) (◯ mark) is suppressed as compared with Comparative Example 1 (■ mark), showing that the stress leak current resistance is high. (Determination of nitrogen concentration) In Example 1 and Comparative Example 2,
The amount of nitrogen introduced into the silicon oxide film was analyzed using SIMS (secondary ion mass spectrometry). SIMS
The sample for analysis does not have a gate electrode formed, and is shown in FIG.
Although it has a structure as described above, it is substantially the same silicon-based insulating film as in Example 1 and Comparative Example 2. This S
The analysis conditions of nitrogen by IMS are as follows.

[0030]

[Table 3] Primary ion species: Cs ⁺ , Primary ion acceleration voltage: 2.0 kV, Primary ion current: 8 nA, Primary ion beam diameter: 50 μmφ, Detection secondary ion species: ⁴² Si + N Implemented in FIG. The result of SIMS analysis of Example 1 (f) is shown.
Nitrogen is present more in the interface between the film and the silicon substrate than in the silicon-based insulating film. This tendency is shown in other Example 1,
The same was true for Comparative Example 2. (Dependence of Stress Leakage Current on Nitrogen Concentration) FIG. 4 shows the dependency of stress leakage current on nitrogen concentration in Example 1, Comparative Example 1 and Comparative Example 2. The horizontal axis represents the amount of nitrogen at the interface between the silicon-based insulating film and the silicon substrate, which was obtained by SIMS analysis, and the vertical axis was obtained from the current / voltage characteristics.
The electric field is the current density at -7 MV / cm. (A) to (f) of Example 1 and (g) and (h) of Comparative Example 2
In each of the films obtained under the above condition, the stress leak current is suppressed as compared with the film of Comparative Example 1 which is not nitrided. Furthermore, in Example 1, the stress leak current decreased as the nitrogen amount increased, and the nitrogen amount dependency of the stress leak current resistance was obtained. That is, from this result, the amount of nitrogen required to obtain the desired stress leak current resistance was found.

On the other hand, in Comparative Example 2, the amount of nitrogen is larger than that in Example 1 because of the nitriding treatment with NH ₃ , but the nitrogen amount dependency as in Example 1 is not obtained. This is considered to be the effect of hydrogen introduced together with nitrogen during the nitriding treatment with NH ₃ . (Allowable Limit of Stress Leakage Current) Here, the allowable limit of stress leak current in the floating gate type flash memory will be described and compared with the results of Example 1 and Comparative Example 1 described above. In the case of a tunnel oxide film (gate insulating film) through which a stress leak current flows, if electrons are left in the floating gate in a state of being accumulated, the electrons leak to the substrate and the threshold voltage changes. Therefore, even if left for 10 years, the change in threshold voltage is 2V.
When the upper limit of the stress leak current which is within the range is defined as the allowable limit, the value is about 1 × 10 ⁻¹⁵ A / cm ² . Further, at this time, the electric field applied to the tunnel oxide film is about −1.
It is 3 V / cm. That is, the allowable limit of the stress leak current is 1 × 10 ⁻¹⁵ A / cm ² or less at an electric field of −1.3 MV / cm.

However, since the lower limit of detection of the measuring instrument used in the above example is about 1 × 10 ^-11 A / cm ² , it was impossible to actually measure the allowable limit. Therefore, the theoretical curve of stress leak current is applied to the measured value, and the value is compared with the allowable limit. The theoretical formula for the stress leak current is P
oolen-Frenkel conduction and trap-assist
ted FN tunneling is known,
Here, it is assumed that the former has a larger leak in the low electric field region. The Poole-Frenkel conduction means that electrons are hopping-conducted by thermal energy in a trap generated during stress application.

FIG. 6 shows the results of comparing the stress leak currents of Example 1 (f) and Comparative Example 1 with the allowable limits.
When compared with the theoretical curve of Poole-Frenkel conduction in which the measured value is extended, Comparative Example 1 in which nitriding is not performed
(Dashed line) violates the allowable limit. However, Example 1
In (f) (solid line), the allowable limit is sufficiently satisfied. That is, when the nitriding treatment is performed and the stress leak is suppressed more than in Comparative Example 1, the allowable limit is satisfied. Therefore, judging from the concentration dependence of FIG. 4, it is found that the nitriding treatment requires a nitrogen amount of 1 × 10 ²⁰ atoms / cm ² or more. The absolute values of the characteristics of FIG. 6 are different from those of FIGS. 3 and 4 because the applied stress is different. In FIG. 6, assuming writing in an actual flash memory, a weak stress of 1 mA / cm ² × 500 seconds was applied. (Embodiment 2) In this embodiment, an example of manufacturing a nonvolatile semiconductor memory device having a floating gate using the silicon-based insulating film obtained by the method of Embodiment 1 will be described.

As shown in FIG. 7A, L is first formed on the surface of a semiconductor substrate 10 made of, for example, a P-type silicon substrate.
An element isolation region 20 made of silicon oxide is formed by the OCOS method. Next, the silicon-based insulating film 13 is formed on the surface of the semiconductor substrate 10 separated by the element isolation regions 20 while controlling the nitrogen concentration contained in the film by using the method of the first embodiment. This silicon-based insulating film 1
Reference numeral 3 denotes a silicon oxide film that has been subjected to a nitriding treatment, and its film thickness is not particularly limited, but is, for example, about 6 to 10 nm. This silicon-based insulating film 13 becomes a gate insulating film (tunnel oxide film).

After that, a silicon-based film 1 to be a gate insulating layer
A first conductive layer, which will become the floating gate 22, is deposited on top of 3. The first conductive layer is composed of, for example, a polysilicon film formed by a CVD method. The thickness of the first conductive layer is not particularly limited, either, but is, for example, 100 to 200 nm.
It is a degree.

Next, the first conductive layer is etched into a striped pattern along a direction substantially orthogonal to the control gates 24 serving as word lines, and then an intermediate insulating layer 23 is deposited thereon. The intermediate insulating layer 23 is not particularly limited, but for example, an ONO film (SiO ₂
/ SiN / SiO ₂ ) is used. The ONO film is formed, for example, as follows.

First, the surface of the first conductive layer is thermally oxidized to
An oxide film having a thickness of about 2 nm or less is formed, a silicon nitride film having a thickness of about 11 nm or less is formed on the thermal oxide film by a CVD method, and the surface thereof is thermally oxidized to an oxide film having a thickness of about 2 nm or less. To form. With such a process, a three-layer structure is turned on.
An O film can be formed. This ONO film has a low leak current and excellent film thickness controllability. The film thickness of this ONO film is about 22 nm or less in terms of silicon oxide film.

Next, the second gate which becomes the control gate 24
A conductive layer is formed on the intermediate insulating layer 22. The second conductive layer is composed of, for example, a polysilicon film or a polycide film deposited by the CVD method. The thickness of the second conductive layer which will be the control gate 24 is not particularly limited, but is set to, for example, about 200 nm or less.

Next, the second conductive layer, the intermediate insulating layer and the first
The conductive layer is sequentially etched to obtain a control gate 24, an intermediate insulating layer 23 and a floating gate 22 which will be word lines for each memory cell transistor.
Next, using the control gate 24 as a mask, ion implantation for self-aligned formation of the source / drain regions 26 (see FIG. 7B) is performed. As the conductivity type of the impurities used in the ion implantation step, an impurity of a conductivity type opposite to the conductivity type of the semiconductor substrate 10 is used, and in this embodiment, N type impurities are used. The source / drain region is a so-called LD
A D structure is preferable.

Next, as shown in FIG. 7B, an interlayer insulating layer 28 is deposited on the control gate 24 by the CVD method or the like. The interlayer insulating layer 28 is composed of, for example, a silicon oxide layer, a silicon nitride layer, a PSG layer, a BPSG layer, or the like. The film thickness of the interlayer insulating layer 28 is not particularly limited and is, for example, about 200 to 300 nm. Next, bit line contact holes 30 and 32 are formed in the interlayer insulating layer 28 by means such as etching.

Next, a metal wiring layer to be a bit line is formed so as to enter the contact holes 30 and 32. The metal wiring layer is made of, for example, Al-1% Si. According to this embodiment, it is possible to manufacture a nonvolatile semiconductor memory device having a gate insulating film (tunnel oxide film) having excellent resistance to stress leak current.

The present invention has been described above based on the preferred embodiments, but the present invention is not limited to these embodiments. As the humidified oxidation method, for example, a conventional humidified oxygen method in which water vapor is mixed with a carrier gas such as oxygen, nitrogen, or argon, or dry oxygen is passed through a water bubbler can be adopted. Also, the conditions of the nitriding treatment are merely examples,
In addition to N ₂ O, nitric oxide such as NO or NO ₂ can be used as the atmosphere in a single kind or in a mixture of plural kinds. Further, as a heating method for the nitriding treatment, a treatment using a conventional diffusion furnace other than the infrared irradiating device can be performed, and it is needless to say that the nitriding temperature and time can be appropriately changed.

Furthermore, the silicon-based insulating film obtained by the method of the present invention is not necessarily used as a single layer, but can be used as a laminated insulating film with other films. Furthermore, the device in which the film obtained by the method of the present invention is used is not limited to a nonvolatile semiconductor memory device such as an EEPROM, but can be applied to other devices that require stress leak current resistance.

[0044]

In the method of forming a silicon-based insulating film according to the present invention, the dangling bond of Si or O, which is considered to be the cause of the trapping unit, can be terminated by nitrogen, and the stress leak of the silicon-based insulating film can be achieved. The current resistance can be improved.

Further, in the present invention, the concentration of nitrogen introduced into the oxide film and near the interface between the oxide film and the silicon substrate is controlled by controlling the temperature and time for nitriding the silicon oxide film. As a result, the stress leak current resistance can be improved without deteriorating the transistor characteristics.

In the present invention, when a gas in the form of nitric oxide (NO), nitrogen dioxide (NO ₂ ) or dinitrogen monoxide (N ₂ O) is used as the nitriding atmosphere,
It is possible to prevent hydrogen from being mixed into the film during the nitriding treatment and further improve the stress leak current resistance of the obtained silicon-based insulating film.

Further, in the present invention, when the silicon oxide film is formed by the wet oxidation method, the stress leak current resistance of the finally obtained silicon-based insulating film is further improved.

[Brief description of drawings]

1A to 1C are schematic partial cross-sectional views of a semiconductor substrate or the like for explaining a method for forming a silicon-based insulating film according to the present invention.

FIG. 2 is a schematic diagram of a circuit used for measuring current / voltage characteristics and stress leak current.

FIG. 3 is a diagram showing measurement results of current-voltage characteristics of a silicon-based insulating film formed by the method described in Example 1 (f) and Comparative Example 1 before and after applying stress.

FIG. 4 is a diagram showing a correlation between a nitrogen concentration and a stress leak current of a silicon-based insulating film formed by the method described in Example 1, Comparative example 1 and Comparative example 2.

5A and 5B are diagrams showing SIMS analysis results of a silicon-based insulating film formed by the method described in Example 1 (f).

FIG. 6 is a diagram showing a comparison of a stress leak current of a silicon-based insulating film formed by the method described in Example 1 (f) and Comparative example 1 with an allowable limit.

7A and 7B are views showing a manufacturing process of a nonvolatile semiconductor memory device according to another embodiment of the present invention.

[Explanation of symbols]

 10 ... Semiconductor substrate 12 ... Silicon oxide film 13 ... Silicon insulating film 14 ... Gate electrode 20 ... Element isolation region 22 ... Floating gate 24 ... Control gate 26 ... Source / drain region

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/318

Claims (11)

[Claims] 1. A silicon substrate is oxidized to form a silicon oxide film, and then the silicon oxide film is nitrided in a nitrogen oxide atmosphere to obtain a desired stress leak current resistance. A method for forming a silicon-based insulating film, which is controlled by the concentration. 2. The concentration of nitrogen introduced into the silicon oxide film or near the interface between the silicon oxide film and the silicon substrate by the nitriding treatment is 1 × 10 ²⁰ atoms / c.
The method for forming a silicon-based insulating film according to claim 1, wherein the thickness is at least m ³ . 3. The concentration of hydrogen introduced into the silicon oxide film or near the interface between the silicon oxide film and the silicon substrate by the nitriding treatment is 5 × 10 ²⁰ atoms / c.
The method for forming a silicon-based insulating film according to claim 1 or 2, wherein m ³ or less. 4. The nitric oxide atmosphere comprises nitric oxide (N
O), nitrogen dioxide (NO ₂ ), or nitrous oxide (N
_The method for forming a silicon-based insulating film according to any one of claims 1 to 3, wherein the atmosphere contains a gas in the form of ₂ O). 5. The nitriding treatment is performed at 800 to 1200 ° C.
The method for forming a silicon-based insulating film according to any one of claims 1 to 4, wherein the method is performed in the temperature range of. 6. The method for forming a silicon-based insulating film according to claim 1, wherein the nitriding treatment is heated by irradiation with infrared rays. 7. The method for forming a silicon-based insulating film according to claim 1, wherein the film thickness of the silicon-based insulating film after the nitriding treatment is within a range of 5 to 10 nm. . 8. The method for forming a silicon-based insulating film according to claim 1, wherein the method for forming the silicon oxide film is a wet oxidation method. 9. A semiconductor device having a silicon-based insulating film formed by using the method according to claim 1. 10. The method according to claim 1, which is formed on the surface of a silicon substrate.
Forming a gate insulating film made of a silicon-based insulating film by using any one of the methods 1 to 8; forming a floating gate on the surface of the gate insulating film; and forming an intermediate insulating film on the surface of the floating gate. A method for manufacturing a non-volatile semiconductor memory device, comprising: a forming step; and a step of forming a control gate on the surface of the intermediate insulating film. 11. A non-volatile semiconductor memory device manufactured by using the method according to claim 10.