JPH0855848A - Heating treatment method of silicon oxide film - Google Patents

Abstract

PURPOSE:To obtain a gate insulating film whose characteristic is good by a method wherein a silicon oxide film which is kept at a temperature in a specific range is irradiated with ultraviolet rays in a dinitrogen monoxide atmosphere and the silicon oxide film which is kept at a temperature in a specific range is irradiated with ultraviolet rays in a hydrogen nitride atmosphere. CONSTITUTION:A silicon oxide film as a substratum is formed on a substrate 105, and an amorphous silicon film is formed. After that, a heating treatment is executed in an N2 atmosphere, and the amorphous silicon film is crystallized. The crystallized silicon film is etched, an island-shaped region is formed, and a silicon oxide film as a gate insulating film is formed. The substrate 105 is placed on a substrate holder 104. N2O is introduced into a chamber 101 from a gas introduction system 107, and a heating treatment is executed at a temperature of 300 to 700 deg.C while ultraviolet rays are being emitted from an ultraviolet light source 106 in a 100-% N2O atmosphere. After that the N 0 inside the chamber is evacuated NH is introduced and a heating treatment is executed at a temperature of 300 to 700 deg.C while ultraviolet rays are being emitted from the ultraviolet light source 106 in a 100-% NH3 atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an insulating substrate such as glass,
Alternatively, a semiconductor device provided on an insulating film formed on various substrates, for example, a thin film transistor (TFT)
Alternatively, the present invention relates to a method for manufacturing a thin film integrated circuit, particularly a thin film integrated circuit for an active liquid crystal display device (liquid crystal display), which is applied to the method, and particularly to a heat treatment method for a gate insulating film for obtaining a gate insulating film having good characteristics, The present invention relates to a heat treatment device.

[0002]

2. Description of the Related Art In recent years, semiconductor devices having TFTs on an insulating substrate such as glass, for example, active type liquid crystal display devices using TFTs for driving pixels and image sensors have been developed. TFTs used in these devices include
Generally, a thin film silicon semiconductor is used. The thin film silicon semiconductor is roughly classified into two types, that is, an amorphous silicon semiconductor and a crystalline silicon semiconductor. Amorphous silicon semiconductors have a low production temperature, can be produced relatively easily by the vapor phase method, and have high mass productivity.
Although most commonly used, the physical properties such as conductivity are inferior to those of crystalline silicon semiconductors. Therefore, in order to obtain higher speed in the future, a method of manufacturing a TFT made of crystalline silicon semiconductors. There is a strong demand for establishment.

TFT using amorphous silicon having low mobility
In this case, the characteristics of the gate insulating film did not pose a problem. For example, in a TFT using amorphous silicon, a silicon nitride film having electric characteristics inferior to that of silicon oxide is used as a gate insulating film. However, in a TFT using a crystalline silicon film having high mobility, the characteristics of the gate insulating film are as great a problem as the characteristics of the silicon film itself. A thermal oxide film is preferable as the gate insulating film. For example, a gate insulating film could be obtained by using a thermal oxidation method on a substrate such as a quartz substrate that can withstand high temperatures. (For example, Japanese Patent Publication No. 3-71793)

A high temperature of 950 ° C. or higher is required to obtain a silicon oxide film that can be used as a gate insulating film by the thermal oxidation method. However, there is a substrate material other than quartz that can withstand such a high-temperature treatment, and the quartz substrate is expensive and has a problem that it is difficult to increase the area because it has a high melting point. However, the cheaper glass substrate materials have a strain point of 750 ° C. or lower, generally 550 to 6
There has been a problem that the substrate cannot withstand the high temperature at 50 ° C. for obtaining a thermal oxide film by a usual method. Therefore, the gate insulating film is formed by a physical vapor deposition method (PVD method, for example, sputtering method) or a chemical vapor deposition method (CVD method, for example, plasma CVD method, optical CVD method, etc.) that can be formed at a lower temperature. .

[0005]

[Problems to be Solved by the Invention] However, PVD
The insulating film formed by the CVD method or the CVD method had a high concentration of dangling bonds or hydrogen, and had poor interface characteristics. Therefore, it is weak against injection of hot carriers and the like, and charge trap centers are easily formed due to dangling bonds and hydrogen. Therefore, when it is used as a gate insulating film of a TFT, the electric field mobility and the subthreshold characteristic value (S value) are not good, or the leak current of the gate electrode is large and the on current decreases (deteriorates).・ There was a problem that the change over time was severe.

For example, in the case of using the sputtering method which is the PVD method, if synthetic quartz composed of high-purity oxygen and silicon is used as a target, in principle only a film of a compound of oxygen and silicon is formed. However, it was extremely difficult to obtain a silicon oxide film in which the ratio of oxygen to silicon in the obtained coating is close to the stoichiometric ratio and the number of dangling bonds is small. For example,
Oxygen was the preferred sputter gas. However, oxygen has a small atomic weight and a low sputtering rate (deposition rate), and is unsuitable as a sputtering gas when considering mass production.

Further, although a sufficient film formation rate was obtained in an atmosphere of argon or the like, the ratio of oxygen to silicon was different from the stoichiometric ratio, which was extremely unsuitable as a gate insulating film. Furthermore, it is difficult to reduce the dangling bonds of silicon regardless of the sputtering atmosphere, and by performing heat treatment in a hydrogen atmosphere after film formation,
Si-H, which is a dangling bond of silicon
It was necessary to stabilize as Si-OH.
However, the Si-H and Si-OH bonds are unstable,
It was easily broken by the accelerated electrons and converted into the original dangling bonds of silicon. Such a weak bond S
The presence of i-H and Si-OH is a cause of the deterioration due to the hot carrier injection.

Similarly, a silicon oxide film produced by the plasma CVD method also contains a large amount of hydrogen in the form of Si--H and Si--OH, which has been a source of the above problems.
In addition, when tetra-ethoxy-silane (TEOS) is used as a silicon source that is relatively easy to handle, there is a problem that a high concentration of carbon is contained in the silicon oxide film. The present invention provides means for solving the above problems.

[0009]

The first aspect of the present invention is CVD.
Method or PVD method, while irradiating the silicon oxide film deposited on the active layer with ultraviolet light, in a dinitrogen monoxide (N ₂ O) atmosphere, 300 to 700 ° C., preferably,
Heat treatment is performed at 500 to 600 ° C., and then the atmosphere is changed to a hydrogen nitride atmosphere such as ammonia (NH ₃ ) or hydrazine (N ₂ H ₄ ) and 300 to 700 ° C. in the atmosphere while irradiating with ultraviolet light. , Preferably 500-
Heat treatment at 600 ° C. is performed. At this time, the wavelength of the ultraviolet light used is 100 to 350 nm, preferably 1
It is set to 50 to 300 nm.

The above steps are performed in one reaction chamber (chamber).
In the case of the above, it is necessary to convert the atmosphere from N ₂ O to hydrogen nitride. At this time, it is desirable to introduce hydrogen nitride after the concentration of N ₂ O becomes sufficiently low. This is because there is a high possibility of explosion when N ₂ O and hydrogen nitride are mixed. Therefore, it is preferable to introduce the hydrogen nitride after first evacuating the chamber in the N ₂ O atmosphere.
More simply, the N ₂ O atmosphere may be replaced with nitrogen to form a nitrogen atmosphere, the concentration of N ₂ O may be sufficiently lowered, and then hydrogen nitride may be introduced.

In the above two heat treatment steps, the temperature may be raised or lowered for each heat treatment step, or may be maintained at a substantially constant temperature. Similarly, in the two heat treatment steps, the ultraviolet light may be radiated / interrupted for each heat treatment step, or may be continuously radiated.

The heat treatment time in each atmosphere of N ₂ O and hydrogen nitride depends on the characteristics of the silicon oxide film, the heat treatment temperature, the intensity of the ultraviolet light, etc., but is set to 30 minutes to 6 hours in consideration of mass productivity. Is desirable. Further, the rate of increase or decrease of the substrate temperature in the heat treatment step may be determined depending on the method for carrying out the present invention, but in consideration of mass productivity, the rate of temperature increase or decrease at a rate of 5 to 30 ° C./min. It is desirable to cool. Further, the temperature raising / cooling may be performed in a nitrogen atmosphere.

In the present invention, for example, the PVD method is a sputtering method, and the CVD method is a plasma CVD method.
Method, low pressure CVD method, or atmospheric pressure CVD method may be used. Other film forming methods can also be used. Further, as the plasma CVD method or the low pressure CVD method, TEOS is used.
You may use the method made from. In the former case, TEOS and oxygen gas may be used as the main raw materials and deposited at a substrate temperature of 200 to 500 ° C. In the latter case, a silicon oxide film free from plasma damage can be obtained at a relatively low temperature (for example, 375 ° C. ± 20 ° C.) using TEOS and ozone as raw materials. Similarly, by using the low pressure CVD method, a silicon oxide film can be obtained without causing plasma damage to the active layer even when monosilane (SiH ₄ ) and oxygen gas (O ₂ ) are used as main raw materials.
Further, among the plasma CVD methods, the ECR-CVD method, which uses discharge under ECR (electron cyclotron resonance) conditions, causes less damage due to plasma, so that a better gate insulating film can be formed. These film forming means are the same in the following second invention.

The second aspect of the present invention is the CVD method or PVD.
By irradiating the silicon oxide film deposited on the active layer with ultraviolet light by a method of 300 to 70 in a hydrogen nitride atmosphere.
The heat treatment is performed at 0 ° C., preferably 500 to 600 ° C., and then the atmosphere is changed to an N ₂ O atmosphere, and while irradiating with ultraviolet light, the atmosphere is 300 to 700 ° C., preferably 500 to 600 ° C. Heat treatment. Also at this time, the wavelength of the ultraviolet light used is 100 to 3
The thickness is 50 nm, preferably 150 to 300 nm. In the above process, when converting the atmosphere from hydrogen nitride to N ₂ O, the same precautions as in the first invention are necessary.
Further, similarly to the first aspect of the invention, the temperature rise / fall or the ultraviolet light irradiation / interruption may be controlled. The same applies to the heat treatment time.

In order to carry out the first and second aspects of the present invention, a reaction chamber (chamber) having an apparatus capable of controlling the atmosphere and an apparatus for ultraviolet light irradiation is required. Specifically, a chamber for heat treatment, a preparatory chamber for setting the substrate before the heat treatment and the substrate after the heat treatment, and a front chamber provided with a carrier for transferring the substrate. And the chamber is provided with a substrate holder provided with a heater for heating the substrate, and the outside or inside of the chamber for heating the substrate,
In the heat treatment apparatus, a light source for irradiating the substrate with ultraviolet light is attached. Also, N ₂ O
A plurality of chambers may be provided so that heat treatment in an atmosphere and heat treatment in a hydrogen nitride atmosphere can be performed in different chambers.

In this apparatus, in order to further improve the productivity, the substrate holder inside the chamber is made into a substantially conveyor-shaped carrier made of heat-resistant metal, and the heat treatment can be performed while moving the substrate. It may be like this. Further, the substrate holder inside the chamber for heating the substrates may be a conveyor-like transfer device made of heat-resistant metal so that a plurality of substrates can be attached and heat treatment can be performed at once. . Further, a heater may be provided below the roughly conveyor-shaped transport device.

Another apparatus of the present invention has a cylindrical chamber, and a heater for heating a substrate is provided around the cylindrical chamber, and the central portion of the cylindrical chamber is provided. Is provided with a light source for irradiating the substrate with ultraviolet light, and has a structure for mounting the substrate along the inner wall of the cylindrical chamber. By doing so, the ultraviolet light can be effectively used and the productivity can be improved.

[0018]

When the process described in the first invention is applied to the silicon oxide film formed by the CVD method or the PVD method, the first heat treatment in the N ₂ O atmosphere causes the Si-- The H bond and the Si-OH bond are nitrided or oxidized to change to Si≡N or Si ₂ = N—O bond, and the hydrogen in the silicon oxide film is reduced. Further, thereafter, by heat treatment in a hydrogen nitride atmosphere, dangling bonds (dangling bonds) that could not be filled in by the above reaction are nitrided or hydrogenated, and become stable.

In the present invention, ultraviolet light (wavelength 100 to 100)
The effect of irradiation of 350 nm, preferably 150 to 300 nm) is very large. That is, the above reaction did not proceed at all without the irradiation of ultraviolet light. A temperature of at least 900 ° C. was required to achieve such a reaction purely by heat treatment. That is, N ₂ O
The temperature required for the thermal decomposition of hydrogen and hydrogen nitride is 900 ° C
Because it was above. However, the temperature of the above reaction can be lowered by irradiating with ultraviolet light.
First, since N ₂ O and hydrogen nitride are decomposed by ultraviolet light, the above-mentioned high temperature is not always necessary, and is 300 to 700 ° C., preferably 500 to 600 ° C.
It is presumed that the same reaction as above was possible even in the heat treatment of.

Further, in the silicon oxide film irradiated with ultraviolet light, dangling bonds, Si-H bonds, and Si-OH bonds are particularly likely to absorb ultraviolet light, and as a result, such portions are chemically absorbed. It is also considered that the chemical reaction was promoted and the chemical reaction was promoted. In particular, this reaction easily proceeds at the interface between silicon oxide and silicon, and as a result, nitrogen tends to concentrate at the silicon oxide-silicon interface. The amount of nitrogen concentratedly added near the interface by such means is 10 times or more the average concentration of the silicon oxide film. 0.1 to 1 in silicon oxide
It is preferable for the gate insulating film to contain 0 atom%, typically 1 to 5 atom% of nitrogen.

As a result, unpaired bonds at the interface between the gate insulating film and the active layer, and Si—H bonds and Si—OH bonds, which are weak in bond and are easily broken by hot carriers, have a strong bond Si≡. It is replaced with N bond, Si ₂ ═N—O bond, etc., and the change in chemical state due to hot carriers becomes extremely small.

Thus, in the silicon oxide film, especially in the vicinity of the interface with the silicon film, dangling bonds, Si--H bonds and Si--OH.
By nitriding and oxidizing the bonds, resistance to hot carriers is improved, and when used as a gate insulating film of a TFT, electric field mobility and subthreshold characteristic value (S
Value) was improved, and a remarkable effect was produced in preventing a decrease in on-current (deterioration / aging change).

A silicon oxide film formed by the sputtering method according to the present invention (in particular, a silicon oxide film having an oxygen concentration lower than the stoichiometric ratio by using argon or the like as the sputtering atmosphere).
The effect is particularly remarkable when applied to. That is,
By heat-treating such a film in an N ₂ O atmosphere, it is possible to make up for the deficient oxygen and to bring the composition of the silicon oxide film close to the stoichiometric ratio.
The dangling bonds and the like that have not been filled by the heat treatment in the N ₂ O atmosphere are nitrided by the heat treatment in the subsequent hydrogen nitride atmosphere.

The above shows that the formation of the silicon oxide film by the sputtering method is not disadvantageous. That is,
Conventionally, to form a silicon oxide film by a sputtering method,
In order to bring the composition close to the stoichiometric ratio, it was possible to perform it only in an atmosphere of limited conditions. For example, considering a system of a mixed atmosphere of oxygen and argon as the atmosphere, it is necessary to satisfy the condition of oxygen / argon> 1, and it is preferable to carry out in a pure oxygen atmosphere. Therefore, the film forming rate was low and it was not suitable for mass production. Further, oxygen is a reactive gas, and there is a problem that the vacuum device, the chamber and the like are oxidized.

However, according to the present invention, even a silicon oxide film having a composition deviating from the stoichiometric composition can be converted into a silicon oxide film suitable for use as a gate insulating film, so that the same mixed atmosphere system of oxygen and argon is used. Even in
It can be carried out under more favorable conditions with respect to the film formation rate, such as oxygen / argon ≦ 1. For example, it is possible to form a film under stable conditions with a very high film forming rate as in a pure argon atmosphere.

When the present invention is applied to a silicon oxide film formed by a plasma CVD method using a silicon-containing silicon source such as TEOS, a special effect can be obtained. A large amount of carbon is contained in these silicon oxide films, and in particular, carbon existing near the interface with the silicon film was a cause of deterioration of TFT characteristics. In the present invention, the heat treatment in the N ₂ O atmosphere causes the oxidation to proceed. At that time, carbon is also oxidized and released as carbon dioxide gas to the outside, so that the carbon concentration in the film can be reduced.

As a result, by using the present invention, 3
It is possible to reduce the concentration of hydrogen and carbon and increase the concentration of nitrogen in the silicon oxide film formed by the plasma CVD method using TEOS as the source gas, even at a low temperature of 00 to 700 ° C. The TFT using the silicon oxide film thus treated as the gate insulating film exhibits excellent characteristics and high reliability. When the process described in the second invention is performed on the silicon oxide film formed by the CVD method or the PVD method, the first heat treatment in a hydrogen nitride atmosphere causes the dangling bonds in the silicon oxide film, Si -H
The bond and the Si-OH bond are nitrided and changed to Si≡N or Si-N = H ₂ bond.

Further, after that, by heat treatment in an N ₂ O atmosphere, the hydrogen nitride group (NH
₂ etc.) are nitrided or oxidized, Si≡N bond, Si ₂
= N-O bond or the like. It is the same as the first invention that the effect of irradiation of ultraviolet light is very large in the above reaction. The amount of nitrogen concentratedly added near the interface by such means is 10 times or more the average concentration of the silicon oxide film. 0.1 to 10 atomic% in silicon oxide, typically 1
It is preferable for the gate insulating film to contain nitrogen of about 5 atomic%.

As a result, an unpaired bond at the interface between the gate insulating film and the active layer, or a Si—H bond or a Si—OH bond that is weakly bonded and easily broken by hot carriers, has a strong bond Si≡. It is replaced with N bond, Si ₂ ═N—O bond, etc., and the change in chemical state due to hot carriers becomes extremely small.

As described above, in the silicon oxide film, especially in the vicinity of the interface with the silicon film, dangling bonds, Si--H bonds and Si--OH.
By nitriding and oxidizing the bonds, resistance to hot carriers is improved, and when used as a gate insulating film of a TFT, electric field mobility and subthreshold characteristic value (S
Value) was improved, and a remarkable effect was produced in preventing a decrease in on-current (deterioration / aging change).

A silicon oxide film formed by a sputtering method according to the present invention (especially, a silicon oxide film having an oxygen concentration lower than a stoichiometric ratio by using argon or the like as a sputtering atmosphere).
The effect of the present invention is the same as the effect of the first invention when applied to a silicon oxide film formed by a plasma CVD method using a silicon source containing carbon such as TEOS. .

[0032]

【Example】

[Embodiment 1] This embodiment is an example in which the first and second aspects of the present invention are applied. That is, the film quality is improved by performing a heat treatment in an N ₂ O atmosphere while irradiating the silicon oxide film with ultraviolet light, and then further performing a heat treatment in a hydrogen nitride atmosphere (an ammonia atmosphere in this embodiment). And an example in which an N-channel TFT is formed using this as a gate insulating film, and a silicon oxide film is subjected to heat treatment in a hydrogen nitride atmosphere (ammonia atmosphere in this embodiment) while irradiating ultraviolet light, and then further. This is an example in which the film quality is improved by performing heat treatment in an N ₂ O atmosphere, and an N-channel TFT is formed using this as a gate insulating film. FIG. 7 shows the TFT of this embodiment.
And the heating of the silicon oxide film shown in FIG.
An outline of an apparatus used for ultraviolet light irradiation processing is shown.

First, the underlying silicon oxide film 7 is formed on the substrate 701.
02 was formed to 3000 Å by the plasma CVD method. Then, an amorphous silicon film was formed to a thickness of 500 Å by the plasma CVD method. Then, heat treatment was performed in an N ₂ atmosphere to crystallize the amorphous silicon film. At this time, in order to promote the crystallization of the amorphous silicon film, a trace amount of an element such as nickel that promotes the crystallization of the amorphous silicon may be added. Further, laser annealing may be performed to improve crystallization. (Figure 7 (A))

Next, the crystallized silicon film 703 was etched to form island regions 704. This island region 70
Reference numeral 4 is an active layer of the TFT. Then, a 1000 Å silicon oxide film 705 was formed as a gate insulating film. In this example, a silicon oxide film was produced by the following first to third different methods. (FIG. 7 (B)) The first is by a plasma CVD method using TEOS as a raw material. This is because TEOS and oxygen vaporized by a vaporizer are introduced into a chamber having parallel plate type electrodes, and RF power (for example, a frequency of 13.56 MH is supplied).
z) is introduced to generate plasma and the substrate temperature is 200
It is a method of depositing a silicon oxide film at ˜500 ° C., preferably 250 to 400 ° C. In this example, the reaction pressure is 4
Pa, input power was 150 W, and substrate temperature was 350 ° C.

The second is by the sputtering method. This uses synthetic quartz as a target, oxygen 100%,
The film is formed by sputtering in an atmosphere of 1 Pa. Input power 350W, substrate temperature 2
It was set to 00 ° C. The third is by the ECR-CVD method,
Monosilane (SiH ₄ ) and oxygen were used as source gases. Nitrogen oxide gas such as N ₂ O, NO, NO ₂ may be used instead of oxygen. Further, the film forming conditions at this time are microwave (frequency 2.4) without substrate heating.
Input power of 5 MHz) was set to 400W.

Then, the first and second heat treatments of the present invention were performed on each of the silicon oxide films thus formed. As shown in FIG. 1, the heat treatment apparatus used in the present embodiment has a chamber 10 for performing heat treatment.
1, a preparatory chamber 102 in which pre-processed substrates are stored, a preparatory chamber 103 in which post-processed substrates are stored, and a pre-chamber 109 equipped with a carrier 110. The substrate 111 is these chambers. It is transferred by the carrier 110. In the present embodiment, the chamber 101 is of a single-wafer type that can process one sheet at a time.

Further, the chamber 101 has a substrate holder 104 provided with a heater for heating the substrate 105 at the bottom. Further, an ultraviolet light source 106 is provided outside the chamber 101. In this embodiment, a low pressure mercury lamp (center wavelength 24
6 nm, and 185 nm) were used. Chamber 1
In the upper part of 01 where the ultraviolet light source 106 is attached, a window is formed by a material such as quartz that does not absorb the ultraviolet light in order to take in the ultraviolet light. Although the ultraviolet light source is installed outside the chamber in this embodiment, it may be installed inside the chamber.

Further, the chamber 101 and the antechamber 109 are provided with an exhaust system 108 for exhausting gas and a gas introducing system 107 for introducing gas. First, the first heat treatment of the present invention will be described. First, a plurality of unprocessed substrates were set in a cassette and set in the preliminary chamber 102. The substrate is then transferred to the front chamber 1 by the carrier 110.
09, where the evacuation system was evacuated to depressurize the front chamber and then transferred to the already depressurized chamber 101 for heat treatment and set on the substrate holder 104.

Then, N ₂ O is introduced into the chamber 101 from the gas introduction system 107, and in a substantially 100% N ₂ O atmosphere in which the pressure inside the chamber is atmospheric pressure,
The heat treatment was performed while irradiating with ultraviolet light. On this occasion,
The heating temperature was 350 to 600 ° C., for example 500 ° C.
The heat treatment was performed for 30 minutes to 6 hours, for example, 3 hours. Then, N ₂ O in the chamber was evacuated and NH ₃ was introduced. At this time, NH ₃ was introduced after the N ₂ O was sufficiently exhausted to a low concentration. In this manner, NH ₃ was introduced, and the heat treatment was performed while irradiating with ultraviolet light in a substantially 100% NH ₃ atmosphere in which the pressure inside the chamber was atmospheric pressure. At this time, the heating temperature was 500 ° C., and the processing time was 3 hours.

After the heat treatment is performed twice, the processed substrate is transferred by the carrier 110 to the front chamber 109.
Preliminary chamber 1 where the substrates after being transferred to
It was set in the cassette in the No. 03, and the processing step of one substrate was completed. After that, the same process was repeated.
The first heat treatment of the present invention was performed as described above.

In addition to the above, the second heat treatment of the present invention was applied to the three kinds of silicon oxide films produced in the same manner. The process at this time is the reverse of the atmosphere in which the heat treatment in the first process described above is performed. First, NH ₃ was introduced into the chamber 101 from the gas introduction system 107, and the pressure inside the chamber was set to atmospheric pressure, and substantially 100% N 2 was added.
Heat treatment was performed in an H ₃ atmosphere while irradiating with ultraviolet light. At this time, the heating temperature was 500 ° C. The heat treatment was performed for 3 hours.

Then, NH ₃ in the chamber was evacuated and N ₂ O was introduced. At this time, the introduction of N ₂ O was performed after the NH ₃ was sufficiently exhausted to a low concentration.
In this way, by introducing N ₂ O, the pressure inside the chamber is set to atmospheric pressure, and in a substantially 100% N ₂ O atmosphere,
The heat treatment was performed while irradiating with ultraviolet light. On this occasion,
The heating temperature was 500 ° C., and the heating time was 3 hours.

After the heat treatment is performed twice, the processed substrate is transferred to the front chamber 109 by the carrier 110.
Preliminary chamber 1 where the substrates after being transferred to
It was set in the cassette in the No. 03, and the processing step of one substrate was completed. After that, the same process was repeated.
The second heat treatment of the present invention was performed as described above.

As described above, the silicon oxide films formed by the three kinds of film forming methods were respectively subjected to two kinds of heat treatments. The samples subjected to the heat treatment of the six kinds of ultraviolet light combined use were subjected to secondary ion treatment. As a result of analysis by mass spectrometry (SIMS), the amount of carbon (C) in the silicon oxide film, especially in the silicon oxide film formed by the above-mentioned first method (TEOS plasma CVD method), was increased at the interface with the silicon film. Was decreased and the amount of nitrogen (N) was increased. At the same time, it was confirmed that hydrogen (H) also decreased. Second method (sputtering method), third method (ECR
In the case of silicon oxide formed by the -CVD method), an increase in the nitrogen concentration at the silicon / silicon oxide interface was similarly confirmed.
The silicon oxide film having such a composition was preferable as the gate insulating film.

For comparison, the silicon oxide film formed by the above-mentioned first to third methods was treated with N ₂ O in the apparatus of FIG.
No change was observed in the concentrations of nitrogen, hydrogen and carbon when heated under the same temperature condition in a nitrogen atmosphere instead of and NH ₃ . After that, 5000 Å thick aluminum (1 wt% Si, or 0.1-0.3 wt% S
A film (including c) was formed by a sputtering method, and this was etched to form a gate electrode 706. Next, the substrate was immersed in a 1% to 3% ethylene glycol solution of tartaric acid adjusted to pH≈7 with ammonia, and anodization was performed using platinum as a cathode and this aluminum gate electrode as an anode. The anodization was completed by first increasing the voltage to 120 V with a constant current and maintaining the state for 1 hour. Thus, an anodic oxide having a thickness of 1500 Å was formed.

After that, impurities (phosphorus in this case) were implanted into the island-shaped silicon film 704 in a self-aligned manner by ion doping using the gate electrode 706 as a mask. In this case, the dose amount is 1 × 10 ^{14 to} 5 × 10 ¹⁵ atoms / cm ² , the accelerating voltage is 10 to 90 kV, for example, the dose amount is 1 × 10 ^15.
The atom / cm ² and the acceleration voltage were 80 kV. As a result,
N-type impurity region 707 was formed. (FIG. 7C) Further, a KrF excimer laser (wavelength 248 nm, pulse width 20 nsec) was irradiated to activate the doped impurity region 707. The energy density of the laser was 200 to 400 mJ / cm ² , preferably 250 to 300 mJ / cm ² . This step may be performed by heat treatment.

Next, as the interlayer insulating film 708, a silicon oxide film was formed to a thickness of 4000 Å by the plasma CVD method. (FIG. 7D) Then, the interlayer insulating film 708 and the gate insulating film 705 were etched to form contact holes in the source / drain. After that, an aluminum film is formed by a sputtering method and patterned to form a source / drain electrode 709, and an N-channel TFT.
Was produced.

The deterioration of the TFT manufactured in this example was evaluated. The manufacturing method of the TFT includes the method of manufacturing the gate insulating film (any one of the first to third) and the method of manufacturing the gate insulating film
Heat treatment method (N ₂ O atmosphere + NH ₃ atmosphere / with UV light irradiation / 500 ° C / 3 hours each (The above conditions are "N ₂ O
/ NH ₃ atmosphere ”) or the second heat treatment method (NH ₃ atmosphere + N ₂ O atmosphere / with ultraviolet light irradiation /
500 ° C / 3 hours each (the above conditions are referred to as "NH ₃ / N ₂ O atmosphere") or N ₂ atmosphere / no ultraviolet light irradiation / 500 ° C / 6 hours (the above conditions are "N ₂ atmosphere" It is the same except that any one of ()) is changed as shown in the table below. The obtained TFT has a drain voltage of + 14V.
The drain voltage was measured while the gate voltage was varied from −17V to + 17V. This measurement was performed 10 times, and the field effect mobilities μ ₀ and 10 obtained by the first measurement were obtained.
Field effect mobility μ ₁₀ obtained by the second measurement is compared,
1- (μ ₁₀ / μ ₀ ) was defined as the deterioration rate. The result is
Shown in the table below. (The negative sign of the deterioration rate means that the mobility has increased)

Sample name Gate insulating film forming method Heat treatment method Deterioration rate A-1 1st (TEOS plasma CVD) N ₂ O / NH ₃ atmosphere 3.2% A-2 1st (TEOS plasma CVD) NH ₃ / N ₂ O atmosphere 3.7% A-3 1st (TEOS plasma CVD) N ₂ atmosphere 48.5% B-1 2nd (sputtering method) N ₂ O / NH ₃ atmosphere-2.7% B -2 second (sputtering) NH ₃ / N ₂ O atmosphere -2.3% B-3 second (sputtering) N ₂ atmosphere 11.9% C-1 the 3 (ECR-CVD method) N ₂ O / NH ₃ atmosphere 0.7% C-2 3rd (ECR-CVD method) NH ₃ / N ₂ O atmosphere 1.2% C-3 3rd (ECR-CVD method) N ₂ atmosphere 20.5%

As described above, in any of the samples, after irradiation with ultraviolet light during the heat treatment in the N ₂ O atmosphere of the present invention, the ultraviolet light was further irradiated during the heat treatment in the NH ₃ atmosphere. Or vice versa, by irradiating with ultraviolet light when performing heat treatment in an NH ₃ atmosphere, and then further irradiating with ultraviolet light when performing heat treatment in an N ₂ O atmosphere. It became clear that the deterioration rate was significantly reduced. Even if the heat treatment and the ultraviolet light irradiation treatment were performed in the N ₂ atmosphere, the effect of reducing the deterioration rate was not observed. Also, from the same experiment, N ₂ O atmosphere or NH
It was also clarified that no improvement was observed in the deterioration rate unless UV light was applied during the heat treatment in the _three atmospheres.

Although the TFT manufactured in this example uses the silicon oxide film manufactured by the PVD method or the CVD method for the gate insulating film, it has good durability and little deterioration, and , The one with excellent characteristics was obtained. This, after the N ₂ O atmosphere according to the invention was subjected to heat treatment of ultraviolet irradiation in combination, further or subjected to heat treatment of ultraviolet irradiation in combination in NH ₃ atmosphere, or ultraviolet irradiation combined in NH ₃ atmosphere This is because the carbon and hydrogen in the silicon oxide film are reduced and the nitrogen is increased by further performing the heat treatment combined with the ultraviolet light irradiation in the N ₂ O atmosphere after the heat treatment.

[Embodiment 2] In this embodiment, a silicon oxide film formed on a silicon film is subjected to heat treatment by a plasma CVD method using TEOS as a raw material, using the heat treatment apparatus shown in FIG. It is an example. The silicon oxide film used in this embodiment was formed by the first method of the silicon oxide film 705 (see FIG. 7B) of the embodiment. As shown in FIG. 2, the heat treatment apparatus used in this example is different from the single-wafer type chamber shown in the first example, and is composed of only a chamber for performing heat treatment, and a plurality of chambers are provided at one time. It has a batch type structure that can process one substrate.

The chamber 201 of this embodiment has a cylindrical shape, and the substrate 203 can be installed along the inner wall thereof. The substrate 203 is heated by a heater 202 provided around the chamber 201. Further, an ultraviolet light source 204 is provided in the center of the chamber 201 so that all the substrates are uniformly irradiated with the ultraviolet light. In this example, a low-pressure mercury lamp (center wavelength: 246 nm and 185 nm) was used as an ultraviolet light source. Also, in the chamber,
An exhaust system 206 for performing exhaust and a gas introduction system 205 for introducing gas are provided.

A processing method using this processing apparatus will be described. First, the substrate 203 was set along the inner wall of the chamber 201 so as to surround the ultraviolet light source 204. Then, N _{2 is} introduced into the chamber 201 from the gas introduction system.
Was introduced to replace the inside of the chamber with N ₂ . At this time, air was exhausted from the exhaust system 206 so that the inside of the chamber always maintained a constant pressure. Next, the inside of the chamber is N ₂
When replaced with, the heater was heated and UV irradiation was performed. At this time, the heating temperature was 300 to 700 ° C., for example, 500 ° C. When the substrate is heated to the specified temperature, N
₂ was replaced with N ₂ H ₄ and irradiated with ultraviolet light. At this time, heat treatment was performed for 30 minutes to 6 hours, for example, 2 hours.

Then, N ₂ in the chamber was introduced again to replace N ₂ H ₄ with N ₂ . And then N _2
It was replaced with ₂ O and irradiated with ultraviolet light to carry out a second heat treatment. At this time, the heating temperature was 500 ° C. and the processing time was 2 hours. When the silicon oxide film subjected to the above-mentioned treatment was analyzed by secondary ion mass spectrometry (SIMS), nitrogen was increased and carbon and hydrogen were decreased compared with the nitrogen concentration contained in the initial silicon oxide film. ,
In particular, accumulation of nitrogen was observed at the interface with the silicon film.

[Embodiment 3] In this embodiment, a silicon oxide film formed on a silicon film by a plasma CVD method using TEOS as a raw material is subjected to a heat treatment using a heat treatment apparatus shown in FIG. It is an example. The silicon oxide film used in this embodiment was formed by the first method of the silicon oxide film 705 (see FIG. 7B) of the embodiment.

As shown in FIG. 3, the heat treatment apparatus used in the present embodiment has a chamber 30 for heat treatment.
1, a preliminary chamber 302 for storing unprocessed substrates, a preliminary chamber 303 for storing processed substrates, and a carrier 306.
It comprises front chambers 304 and 305 provided with 307, and substrates 308 and 309 are transferred between these chambers by transfer machines 306 and 307. In this example, the chamber for performing the heat treatment was
It is a batch type in which multiple substrates can be moved at one time by a conveyor and heat treatment can be performed.

FIGS. 4A and 4B show the internal structure of the chamber 301. The chamber 301 is provided with a conveyer 401 made of heat-resistant metal so that heat treatment can be performed while moving the substrate. Further, heaters 406, 407, and 408 for heating the substrate 402 are provided below the conveyor 401. In addition, the heater is the part 4 that raises the temperature of the substrate.
06, a part 407 for heating at a constant temperature, and a part 408 for cooling, which are composed of three different zones.
Further, an ultraviolet light source 409 is provided on the upper portion of the conveyor which is heated at a constant temperature. In this embodiment, a low-pressure mercury lamp (center wavelength: 246n) is used as an ultraviolet light source.
m, and 185 nm) were used.

Further, the chamber 301 is provided with exhaust systems 412, 413 for exhausting gas and gas introducing systems 409, 410, 411 for introducing gas. In the present embodiment, the portions 403 and 405 for heating and cooling the substrate are in the N ₂ atmosphere, and the portion 404 for heating at a constant temperature while irradiating with ultraviolet light is N ₂ O or nitriding. Since it is in a hydrogen atmosphere, a gas introduction system is provided for each part. In addition, exhaust systems 412 and 413 for exhausting the introduced gas are provided near the boundary of each zone. By providing the exhaust systems 412 and 413 at this boundary portion, gas mixture in each zone is prevented.

Next, working steps will be described. First, a plurality of unprocessed substrates were set in a cassette and set in the preliminary chamber 302. Here, in this embodiment, there are two preparatory chambers for setting the unprocessed substrate and two preparatory chambers for setting the treated substrate, respectively. This is because the substrate can be exchanged without stopping the apparatus and the work efficiency is improved. After that, the substrate was transferred to the front chamber 304 by the carrier 306, further transferred to the chamber 301 for heat treatment, and set on the conveyor 401. At this time, two substrates 402 are arranged side by side on the conveyor 401.

Then, in the heating step, the conveyor 4
The temperature gradient on 01 is shown in FIG. First, in the heating zone 403, the substrate is heated at a rate of 5 to 30 ° C./min, for example, 10 ° C./min. At this time,
N ₂ was introduced from the gas introduction system 409, and heating was performed in an N ₂ atmosphere.

Thereafter, the substrate moved to zone 404 where it was heated at a constant temperature. Here, the heat treatment was performed while irradiating ultraviolet light from an ultraviolet light source provided on the conveyor. The heating temperature is 500 to 600 ° C., for example, 5
It was set to 50 ° C. At this time, N ₂ O is fed from the gas introduction system 410.
Was introduced to create an N ₂ O atmosphere. In the zone 404, 20 substrates can be processed at one time. The time required for one substrate to pass through this zone, that is, the time required for one substrate to be heat-treated was 30 minutes to 6 hours, for example, 3 hours.

After such heat treatment, the material is cooled to 250 ° C. by the cooling zone 405. The cooling rate at this time is 5 to 30 ° C./min as in the case of heating,
For example, it was set to 10 ° C./min. At this time, N ₂ was introduced from the gas introduction system 411 to create an N ₂ atmosphere. Then, the processed substrate is transferred to the front chamber 305 by the transfer system 307.
Preliminary chamber 3 where the processed substrate is transferred to
The substrate was set in the cassette in No. 03, and the first substrate processing step was completed.

After that, the substrate after the first substrate processing step was set again in the preliminary chamber 302 and heat treatment was performed. Then, the heating step was performed in the same manner as the previous step. Then, when the substrate was moved to the zone 404 where it was heated at a constant temperature, the heat treatment was performed while the ultraviolet light was radiated from the ultraviolet light source provided on the conveyor. The heating temperature was 550 ° C. At this time, the gas introduction system 4
From 10 NH ₃ was introduced to create an NH ₃ atmosphere.

After such heat treatment, the material is cooled to 250 ° C. by the cooling zone 405. The cooling rate at this time is 5 to 30 ° C./min as in the case of heating,
For example, it was set to 10 ° C./min. At this time, N ₂ was introduced from the gas introduction system 411 to create an N ₂ atmosphere. Then, the processed substrate is transferred to the front chamber 305 by the transfer system 307.
Preliminary chamber 3 where the processed substrate is transferred to
It was set in the cassette in No. 03, and the substrate processing step was completed.

In this way, N which is used in combination with ultraviolet light irradiation
After performing the heat treatment in the ₂ O atmosphere, the heat treatment was further performed in the NH ₃ atmosphere in which the ultraviolet light irradiation was also used. However, in the apparatus shown in Example 1, one substrate is treated. It took about 7 hours, but by using the apparatus shown in this example, the productivity was improved to 20 minutes. The heat treatment of the present invention was performed as described above. As a result of analysis by secondary ion mass spectrometry (SIMS), as a result of heat treatment using ultraviolet light together, the amount of nitrogen increased in the silicon oxide film, particularly at the interface with the silicon film, and carbon and hydrogen It was observed that the concentration of the phenomenon occurred. This was similar to the effect obtained when the heat treatment was performed at 900 ° C. in the same atmosphere.

[Embodiment 4] In this embodiment, a silicon oxide film formed on a silicon film by a plasma CVD method using TEOS as a raw material is subjected to a heat treatment using a heat treatment apparatus shown in FIG. It is an example. The silicon oxide film used in this embodiment was formed by the first method of the silicon oxide film 705 (see FIG. 7B) of the embodiment.

As shown in FIG. 5, the heat treatment apparatus used in this embodiment is a chamber 50 for performing heat treatment.
1, a preparatory chamber 502 in which pre-processed substrates are stored, a preparatory chamber 503 in which post-processed substrates are stored, and a pre-chamber 504 provided with a carrier 505. The substrate 506 is these chambers. It is transferred by a carrier 505. In the present embodiment, the chamber 501 is
It is a batch type in which multiple substrates can be moved at one time by a conveyor and heat treatment can be performed.

FIGS. 6A and 6B show the internal structure of the chamber 501. The chamber 501 is provided with a conveyor 601 made of heat-resistant metal for installing the substrate 602. Also, the conveyor 601
A heater 603 for heating the substrate is provided in the lower part of the. Furthermore, on the upper part of the conveyor 601,
An ultraviolet light source 604 is provided.

Further, the chamber 501 is in an N ₂ atmosphere when heating and cooling the substrate, and in an N ₂ O or hydrogen nitride atmosphere when heating at a constant temperature. 605 is provided. Furthermore, an exhaust system 6 for exhausting the introduced gas
06 is provided. Further, a light source 605 for irradiating the substrate with ultraviolet light is provided. In this embodiment, a low-pressure mercury lamp (center wavelength: 246n) is used as an ultraviolet light source.
m, and 185 nm) were used.

Next, the processing steps will be described. A plurality of unprocessed substrates were set in the cassette and set in the preliminary chamber 502. Then, the substrate is transferred to the front chamber 5 by the carrier 505.
04, and a chamber 50 for heat treatment.
1 and was installed on the conveyor 601. At this time, the substrate 602 is sent on the conveyor 601 and is moved to the side by 2
They are arranged one by one and stopped when a total of 20 sheets are installed. FIG. 6C shows how the temperature changes with time during the heat treatment. When the temperature is raised, the temperature of the substrate is 5 to 30 ° C./mi
n, for example, heated at a rate of 10 ° C./min. At this time, N ₂ was introduced from the gas introduction system 605, and heating was performed in the N ₂ atmosphere.

After that, when the temperature for performing the heat treatment was reached, ultraviolet light was emitted from an ultraviolet light source 604 provided on the conveyor 601. The heating temperature is 500-600 ° C,
For example, heating was performed at 550 ° C. At this time, immediately before the temperature reaches the temperature at which the heat treatment is performed, the gas introduction system 60
It is also possible to introduce NH ₃ from No. 5 and completely perform the heat treatment in the NH ₃ atmosphere when the temperature reaches the heat treatment temperature. The heat treatment time was 30 minutes to 6 hours, for example, 3 hours. After that, NH ₃ is replaced with N ₂
In after replacing, it was performed a second time heat treatment to replace the N ₂ in N ₂ O again. The heat treatment time was 3 hours.

After performing such heat treatment, 25
Cooled to 0 ° C. The cooling rate at this time was 5 to 30 ° C./min, for example, 10 ° C./min, as in the heating. At this time, N ₂ was introduced from the gas introduction system 605 and the treatment was performed in an N ₂ atmosphere. After that, the processed substrate is transferred to the front chamber 504 by the carrier 505, and then set in the cassette in the preliminary chamber 503 in which the processed substrate is set, and the substrate processing step is completed.

The heat treatment of the present invention was performed as described above. Secondary ion mass spectrometry (SIMS) shows that the silicon oxide film contains the same amount of nitrogen as the effect obtained when the heat treatment was performed at 900 ° C. in an N ₂ O atmosphere by the above treatment. ) Confirmed.

[Embodiment 5] In this embodiment, a silicon oxide film formed on a silicon film by a plasma CVD method using TEOS as a raw material is subjected to a heat treatment using a heat treatment apparatus shown in FIG. It is an example. The silicon oxide film used in this embodiment was formed by the first method of the silicon oxide film 705 (see FIG. 7B) of the embodiment.

As shown in FIG. 8, the heat treatment apparatus used in this embodiment has two chambers for heat treatment.
It is divided into a dedicated N ₂ O atmosphere 801 and a dedicated hydrogen nitride (NH _{3 in} this embodiment) atmosphere 802. In addition, a preparatory chamber 803 for storing unprocessed substrates, a preparatory chamber 804 for preserving processed substrates, and a precompartment 806 equipped with a carrier 805 are provided. It is transferred by the carrier 805. In addition,
In the present embodiment, the chamber is of a single-wafer type which can perform one treatment at a time.

Further, the chambers 801 and 802 have substrate holders 809 and 810 provided with heaters for heating the substrates 807 and 808 at the bottoms thereof. Further, ultraviolet light sources 811 and 812 are provided outside the chamber. In this embodiment, a low-pressure mercury lamp (center wavelength: 246 nm, and 185 n) is used as an ultraviolet light source.
m) was used. In the upper part of the chamber where the ultraviolet light source is attached, a window is formed by a material such as quartz that does not absorb the ultraviolet light in order to take in the ultraviolet light.
Although the ultraviolet light source is installed outside the chamber in this embodiment, it may be installed inside the chamber.

An exhaust system 813 for exhausting gas and a gas introducing system 814 for introducing gas are provided in the chamber and the antechamber. Using this apparatus, the first heat treatment of the present invention was performed. First, a plurality of unprocessed substrates were set in a cassette and set in a preliminary chamber 803. Then, the substrate was transferred to the front chamber by the carrier 805, then transferred to the chamber 801 for heat treatment, and set on the substrate holder 809.

Then, a gas introduction system 814 is introduced into the chamber.
Further, N ₂ O was introduced, and heat treatment was performed while irradiating with ultraviolet light in a substantially 100% N ₂ O atmosphere in which the pressure inside the chamber was atmospheric pressure. At this time, the heating temperature was 300 to 700 ° C., for example, 500 ° C. Also,
The heat treatment was performed for 30 minutes to 6 hours, for example, 3 hours. After that, the substrate is moved to the front chamber 806 again by the carrier 805 and transferred to the second chamber 802 where the second heating is performed, and the substrate holder 810
Was installed in. Then, NH ₃ was introduced from the gas introduction system into the chamber, and heat treatment was performed while irradiating with ultraviolet light in a substantially 100% NH ₃ atmosphere in which the pressure inside the chamber was atmospheric pressure. At this time, the heating temperature was 500 ° C. The heat treatment was performed for 3 hours.

After the heat treatment is performed twice, the processed substrate is transferred to the front chamber 806 by the carrier 805.
Preliminary chamber 8 where the processed substrate is placed
It was set in the cassette in 04, and the processing step of one substrate was completed. After that, the same process was repeated.
The heat treatment of the present invention was performed as described above. Secondary ion mass spectrometry (S) shows that the silicon oxide film contains nitrogen in an amount similar to the effect obtained when the heat treatment is performed at 900 ° C. in an N ₂ O atmosphere by the above treatment.
Confirmed by IMS).

Example 6 In this example, monosilane (S
This is an example in which a silicon oxide film formed on a silicon film is subjected to heat treatment using a heat treatment apparatus shown in FIG. 5 by a low pressure CVD method using iH ₄ ) and oxygen gas (O ₂ ) as raw materials. . The conditions for forming the silicon oxide film used in this example are: substrate temperature of 300 to 500 ° C., chamber pressure of 0.1 to 10 torr, eg, 400 ° C., 1.5 to.
rr.

First, a plurality of unprocessed substrates were set in a cassette and set in the preliminary chamber 502. Then, the substrate is transferred to the front chamber 504 by the carrier 505, and further,
It was transferred to the chamber 501 for heat treatment and installed on the conveyor 601. FIG. 6C shows how the temperature changes with time during the heat treatment. When the temperature is raised, the substrate is 5 to 30
C./min, for example, heated at a rate of 10.degree. C./min. At this time, N ₂ was introduced from the gas introduction system 605, and heating was performed in the N ₂ atmosphere.

After that, when the temperature for heat treatment was reached, ultraviolet light (center wavelengths 246 nm and 185 nm) was emitted from an ultraviolet light source 604 provided on the conveyor 601. The heating temperature is 500 to 600 ° C., for example, 5
Heated at 50 ° C. At this time, immediately before the temperature reaches the temperature at which the heat treatment is performed, N _{2 is} supplied from the gas introduction system 605.
When H ₄ was introduced and the temperature at which the heat treatment was carried out was reached, the heat treatment was carried out completely in an N ₂ H ₄ atmosphere. The heat treatment time was 30 minutes to 6 hours, for example, 2 hours. Then, after replacing N ₂ H ₄ with N ₂ , again N
_{A second} heat treatment was performed by replacing ₂ with N ₂ O.
The heat treatment time was 2 hours.

After performing such heat treatment, 25
Cooled to 0 ° C. The cooling rate at this time was 5 to 30 ° C./min, for example, 10 ° C./min, as in the heating. At this time, N ₂ was introduced from the gas introduction system 605 and the treatment was performed in an N ₂ atmosphere. After that, the processed substrate is transferred to the front chamber 504 by the carrier 505, and then set in the cassette in the preliminary chamber 503 in which the processed substrate is set, and the substrate processing step is completed.

The heat treatment of the present invention was performed as described above. Secondary ion mass spectrometry (SIMS) shows that the silicon oxide film contains the same amount of nitrogen as the effect obtained when the heat treatment was performed at 900 ° C. in an N ₂ O atmosphere by the above treatment. ) Confirmed.

[0086]

INDUSTRIAL APPLICABILITY As in the present invention, the PVD method or the CV method is used.
The silicon oxide film formed by the D method is subjected to a heat treatment at a low temperature of about 300 to 700 ° C., preferably about 500 to 600 ° C. in an N ₂ O atmosphere while being irradiated with ultraviolet light, to obtain a silicon oxide film. It was possible to reduce the carbon and hydrogen concentrations therein and to increase the nitrogen concentration at the interface between silicon oxide and silicon.

In the examples, the description has been centered on the silicon oxide film formed by the plasma CVD method using TEOS as a raw material, but the silicon oxide film thus formed contains a large amount of carbon. This is because the effect of the present invention is remarkable. Other PVD or CVD methods, such as
A silicon oxide film formed by a sputtering method, an ECR-CVD method, a low pressure CVD method, an atmospheric pressure CVD method or the like also contains dangling bonds and a large amount of hydrogen, and by carrying out the present invention, It will be apparent that the effect of being able to modify the silicon oxide film suitable as a gate insulating film can be obtained by reducing the concentration of dangling bonds or hydrogen. As described above, by using the silicon oxide film processed according to the present invention as the gate insulating film, it is possible to manufacture a TFT which is not easily deteriorated and has excellent characteristics, and the present invention is an industrially useful invention.

[Brief description of drawings]

FIG. 1 shows a heat treatment apparatus according to a first embodiment.

FIG. 2 shows a heat treatment apparatus according to a second embodiment.

FIG. 3 shows a heat treatment apparatus according to a third embodiment.

FIG. 4 shows the temperature gradient inside the chamber of the heat treatment apparatus according to Example 3 and during heating.

FIG. 5 shows a heat treatment apparatus according to Examples 4 and 6.

FIG. 6 shows temperature gradients inside the chamber of the heat treatment apparatus according to Examples 4 and 6 and during heating.

FIG. 7 shows a process of manufacturing the TFT of Example 1.

FIG. 8 shows the inside of the chamber of the heat treatment apparatus according to the fifth embodiment.

[Explanation of symbols]

 101 ... Heat treatment chambers 102 and 103 ... Preliminary chamber 104 ... Substrate holder 105 ... Substrate 106 ... Ultraviolet light source 107 ...・ Gas introduction system 108 ・ ・ ・ ・ ・ ・ Exhaust system 109 ・ ・ ・ ・ ・ Anterior chamber 110 ・ ・ ・ ・ ・ ・ Conveyor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01L 21/26 21/31 C 29/786 21/336 9056-4M H01L 29/78 617 V (72 ) Inventor Satoshi Teramoto 398 Hase, Atsugi City, Kanagawa Prefecture, Semiconducting Energy Laboratory Co., Ltd. (72) Inventor, Yasuhiko Takemura, 398, Hase, Atsugi City, Kanagawa Prefecture, Semiconducting Energy Laboratory Co., Ltd. (72) Inventor, Shigefumi Sakai, Kanagawa Prefecture 398 Hase, Atsugi City Semiconductor Energy Laboratory Co., Ltd.

Claims (6)

[Claims] 1. A first step of forming a silicon oxide film on an active layer made of crystalline silicon by a CVD method or a PVD method, and the silicon oxide film at 300 ° C. in a dinitrogen monoxide atmosphere.
The second temperature that is maintained above 700 ° C and is irradiated with ultraviolet light
And a third step of irradiating the silicon oxide film with ultraviolet light at a temperature of 300 ° C. or higher and 700 ° C. or lower in a hydrogen nitride atmosphere, and a heat treatment method for the silicon oxide film. 2. A first step of forming a silicon oxide film on an active layer made of crystalline silicon by a CVD method or a PVD method, the silicon oxide film being kept at a temperature of 300 ° C. or higher and 700 ° C. or lower in a hydrogen nitride atmosphere. The second step of maintaining and irradiating with ultraviolet light, and the silicon oxide film in an atmosphere of dinitrogen monoxide at 300 ° C.
Keeping the temperature above 700 ℃ and irradiating with UV light
The heat treatment method for a silicon oxide film, comprising: 3. The silicon oxide film according to claim 1 or 2, wherein the silicon oxide film is tetra ethoxy silane (TEOS, S
Plasma CVD using i (OC ₂ H ₅ ) ₄ ) as source gas
A heat treatment method characterized by being formed by a method. 4. The heat treatment method according to claim 1 or 2, wherein the silicon oxide film is formed by a low pressure CVD method using monosilane (SiH ₄ ) and oxygen gas (O ₂ ) as main raw materials. . 5. The method according to claim 1, wherein, between the second step and the third step, the nitrous oxide atmosphere is replaced with nitrogen to form a nitrogen atmosphere, and the nitrogen atmosphere is replaced with hydrogen nitride. And a step of providing a hydrogen nitride atmosphere. 6. The method according to claim 2, wherein between the second step and the third step, a step of replacing the hydrogen nitride atmosphere with nitrogen to form a nitrogen atmosphere, and replacing the nitrogen atmosphere with dinitrogen monoxide And a step of providing a dinitrogen monoxide atmosphere.