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Patent US5970384 - Methods of heat treating silicon oxide films by irradiating ultra-violet light - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsSilicon oxide films which are good as gate insulation films are formed by subjecting a silicon oxide film which has been formed on an active layer comprising a silicon film by means of a PVD method or CVD method to a heat treatment at 300-700 an NH.sub.3 or N.sub.2 H.sub.4 atmosphere, while irradiating...http://www.google.com/patents/US5970384?utm_source=gb-gplus-sharePatent US5970384 - Methods of heat treating silicon oxide films by irradiating ultra-violet lightAdvanced Patent SearchPublication numberUS5970384 APublication typeGrantApplication numberUS 08/510,288Publication dateOct 19, 1999Filing dateAug 2, 1995Priority dateAug 11, 1994Fee statusPaidAlso published asUS6635589, US20020160622Publication number08510288, 510288, US 5970384 A, US 5970384A, US-A-5970384, US5970384 A, US5970384AInventorsShigefumi Sakai, Mitsunori Sakama, Tomohiko Sato, Yasuhiko Takemura, Satoshi Teramoto, Shunpei YamazakiOriginal AssigneeSemiconductor Energy Laboratory Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (12), Non-Patent Citations (21), Referenced by (58), Classifications (21), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMethods of heat treating silicon oxide films by irradiating ultra-violet lightUS 5970384 AAbstract Silicon oxide films which are good as gate insulation films are formed by subjecting a silicon oxide film which has been formed on an active layer comprising a silicon film by means of a PVD method or CVD method to a heat treatment at 300-700 an NH.sub.3 or N.sub.2 H.sub.4 atmosphere, while irradiating with ultraviolet light, reducing the hydrogen and carbon contents in the silicon oxide film and introducing nitrogen into the boundary with the silicon film in particular. Furthermore, silicon oxide films which are good as gate insulating films have been formed by subjecting silicon oxide films which have been formed on an active layer comprising a silicon film by means of a PVD method or CVD method to a heat treatment at 300-700 atmosphere) while irradiating with ultraviolet light, and then carrying out a heat treatment at 300-700 atmosphere (N.sub.2 O atmosphere), and reducing the amount of hydrogen and carbon in the silicon oxide film and introducing nitrogen into the boundary with the silicon film in particular.
What is claimed is: 1. A method of heat treating a silicon oxide film comprising the steps of:forming a silicon oxide film on a surface; introducing dinitrogen monoxide into a chamber in which heat treatment is carried out; and irradiating an ultraviolet light onto the dinitrogen monoxide and a surface of the silicon oxide film at a temperature of 300 to 700 dinitrogen monoxide atmosphere which has been obtained by means of the introducing step, wherein the surface of the silicon oxide film is nitrided by the irradiating step. 2. The method of claim 1 wherein the silicon oxide film has been formed by means of a plasma CVD method with tetraethoxysilane (TEOS, Si(OC.sub.2 H.sub.5).sub.4) as a raw material gas.
3. The method of claim 1 wherein the silicon oxide film has been formed by means of a low pressure CVD method with monosilane (SiH.sub.4) and oxygen gas (O.sub.2) as raw material gases.
4. The method of claim 1 wherein the heating temperature of the silicon oxide film is at least 500
6. The method of claim 1 wherein the substrate temperature is raised and lowered at a rate of 5-30
7. A method of heat treating a silicon oxide film comprising the steps of:forming a silicon oxide film on a surface; introducing nitrogen into a chamber in which heat treatment is carried out; heating the silicon oxide film at a temperature of at least 300 and not more than 700 irradiated with ultraviolet light in a nitrogen atmosphere, introducing dinitrogen monoxide into the chamber after heating the silicon oxide film sufficiently to displace the nitrogen by dinitrogen monoxide; and irradiating an ultraviolet light onto the dinitrogen monoxide and a surface of the silicon oxide film at a temperature of 300 to 700 dinitrogen monoxide atmosphere obtained by means of the aforementioned steps. wherein the surface of the silicon oxide film is nitrided by the irradiating of the ultraviolet light in the dinitrogen monoxide atmosphere. 8. The method of claim 7 wherein the silicon oxide film has been formed by means of a plasma CVD method with tetraethoxysilane (TEOS, Si(OC.sub.2 H.sub.5).sub.4) as a raw material gas.
9. The method of claim 7 wherein the silicon oxide film has been formed by means of a low pressure CVD method with monosilane (SiH.sub.4) and oxygen gas (O.sub.2) as raw material gases.
10. The method of claim 7 wherein the heating temperature of the silicon oxide film is at least 500
12. The method of claim 7 wherein the substrate temperature is raised and lowered at a rate of 5-30
14. A method of heat treating a silicon oxide film comprising the steps of:forming a silicon oxide film on a surface; introducing dinitrogen monoxide in a chamber in which heat treatment is carried out; irradiating a ultraviolet light onto the dinitrogen monoxide and a surface of the silicon oxide film at a temperature of 300 to 700 wherein nitrogen is excited by the ultraviolet light and is kept in an excited state by the ultraviolet light, and the excited nitrogen is diffused into the silicon oxide film by heat attributed to the temperature used in said irradiating step, and wherein the surface of the silicon oxide film is nitrided by the irradiating step. 15. The method of claim 1 further comprising establishing a vacuum in the chamber before the introducing of the dinitrogen monoxide.
22. A method of heat treating a silicon oxide film comprising the steps of:forming a silicon oxide film on a surface; introducing nitrogen into a chamber in which heat treatment is carried out; heating the silicon oxide film at a temperature of at least 300 and not more than 700 irradiated with ultraviolet light in a nitrogen atmosphere, introducing dinitrogen monoxide into the chamber after heating the silicon oxide film sufficiently to displace the nitrogen by dinitrogen monoxide; and irradiating an ultraviolet light onto the dinitrogen monoxide and a surface of the silicon oxide film in a dinitrogen monoxide atmosphere obtained by means of the aforementioned steps, wherein the surface of the silicon oxide film is nitrided by the irradiating step. 23. The method of claim 22 wherein the silicon oxide film is formed by a PVD method or a CVD method.
A high temperature of at least 950 silicon oxide film which is satisfactory for use as a gate insulating film using the thermal oxidation method. However, there are no other substrates except quartz which can withstand such high temperature treatment, and quartz substrates are expensive and, moreover, there has been a problem in that the production of larger areas has been difficult because the melting point is so high.
However, less expensive glass substrate materials have the problem that their distortion point is less than 750 550-650 temperatures required to obtain a thermal oxide layer using normal methods. Consequently, gate insulating films have been formed using the physical gas phase growing methods (PVD methods, for example the sputter method) and chemical gas phase growing methods (CVD methods, for example the plasma CVD and photo CVD methods) with which they can be formed at lower temperatures.
SUMMARY OF THE INVENTION It is known that silicon oxide films which have a low hydrogen concentration within the silicon oxide film, in which the nitrogen concentration within the silicon oxide film is increased, and which are ideal as gate insulating films can be obtained by subjecting silicon oxide films, for example silicon oxide films which have been formed by thermal oxidation, to a heat treatment at a temperature of at least 900 in an atmosphere of dinitrogen monoxide (N.sub.2 O).
Furthermore, according to research carried out by the inventors, a comparatively high concentration of carbon was included in silicon oxide films which have been formed using the plasma CVD method with TEOS as a raw material, but it was clear that the carbon in the silicon oxide was oxidized and eliminated from the silicon oxide film as carbon dioxide gas on heat treating at a temperature of at least 900 O atmosphere in the same way as described above.
However, the heat treatments carried out at this time are at a high temperature of at least 900 with substrates which have a high distortion point, such as quartz substrates. Consequently, the heat treatment cannot be introduced into the low temperature processes in which TFTs are formed using various glass substrates which have a distortion point below 750 typically of 550-650
The inventors have carried out research with a view to lowering the temperature of this reaction, and they have discovered that an effect similar to that obtained on heat treating at a temperature of at least 900 preferably at 500-600 during heat treatment in an N.sub.2 O atmosphere. The wavelength of the ultraviolet light used at this time is set to 100-350 nm, and preferably to 150-300 nm.
The first invention is characterized by the fact that a silicon oxide film is improved so as to be satisfactory for use as a gate insulating film by heat treating a silicon oxide film, which has been formed by a PVD method or a CVD method, in an N.sub.2 O atmosphere at 300-700 preferably at 500-600 at the same time. Heat treatment at 300-700 500-600 atmosphere such as an ammonia (NH.sub.3) or hydrazine (N.sub.2 H.sub.4) atmosphere, may be carried out prior to the abovementioned heat treatment/ultraviolet light irradiation process. Furthermore, irradiation with ultraviolet light in the same way as in the N.sub.2 O atmosphere may be carried out in the heating process in a hydrogen or hydrogen nitride atmosphere.
The duration of the heat treatment in an N.sub.2 O atmosphere depends on the characteristics of the silicon oxide film, the heat treatment temperature and the intensity of the ultraviolet light, for example, but, in consideration of mass production, it is preferably set to from 30 minutes to 6 hours. Furthermore, the rates of raising and lowering the substrate temperature in the heat treatment process should be determined for the execution of the invention but, in consideration of mass production, the rate at which the temperature is raised and the cooling rate are preferably from 5 to 30 of the temperature and cooling may be carried out in a nitrogen atmosphere.
Furthermore, it is known that by subjecting silicon oxide films, for example silicon oxide films which have been formed by means of the thermal oxidation method, to a heat treatment at a temperature of at least 900 (NH.sub.3) or hydrazine (N.sub.2 H.sub.4) for example, nitriding is effected and the number of unpaired bonds is reduced, thereby increasing the concentration of nitrogen in the silicon oxide film and making it possible to obtain silicon oxide films which are ideal as gate insulating films.
However, the heat treatments carried out at this time are at a high temperature of at least 900 with substrates which have a high distortion point such as quartz substrates. Consequently, the heat treatment cannot be introduced into the low temperature processes in which the TFTs are formed using various glass substrates which have a distortion point below 750 typically of 550-650
The inventors have carried out research with a view to lowering the temperature of this reaction and they have discovered that the same effect as that obtained by carrying out a heat treatment at a temperature of at least 900 300-700 with ultraviolet light during a heat treatment in an NH.sub.3 or N.sub.2 H.sub.4 atmosphere. The wavelength of the ultraviolet light used at this time is set to 100-350 nm, and preferably to 150-300 nm.
The second invention is characterized by the fact that a silicon oxide film is improved so as to be satisfactory for use as a gate insulating film by heat treating a silicon oxide film, which has been formed by a PVD method or a CVD method, in a hydrogen nitride, such as NH.sub.3 or N.sub.2 H.sub.4, atmosphere at 300-700 500-600 time.
The duration of the heat treatment in the hydrogen nitride atmosphere depends on the characteristics of the silicon oxide film, the heat treatment temperature and the intensity of the ultraviolet light, for example, but, in consideration of mass production, it is preferably from 30 minutes to 6 hours. Furthermore, the rates of raising and lowering the substrate temperature in the heat treatment process should be determined for the execution of the invention but, in consideration of mass production, the rate at which the temperature is raised and the cooling rate are preferably from 5 to 30 of the temperature and cooling may be carried out in a nitrogen atmosphere.
The third invention involves carrying out the heat treatment of a silicon oxide film which has been accumulated on an active layer, by means of a CVD method or a PVD method, at 300-700 500-600 while irradiating with ultraviolet light, and then replacing the atmosphere with a hydrogen nitride, such as ammonia (NH.sub.3) or hydrazine (N.sub.2 H.sub.4) for example, atmosphere and carrying out heat treatment at 300-700 the said atmosphere while irradiating with ultraviolet light. At this time the wavelength of the ultraviolet light used is set to 100-350 nm, and preferably 150-300 nm.
In those cases where the abovementioned processes are carried out in a single reaction chamber it is necessary to change the atmosphere from N.sub.2 O to hydrogen nitride. At this time it is desirable that the hydrogen nitride should be introduced after the N.sub.2 O has been reduced to a satisfactorily low concentration. This is because there is a serious danger of explosion if N.sub.2 O and hydrogen nitride are mixed together. Consequently, it is best if the hydrogen nitride is introduced after first evacuating the N.sub.2 O atmosphere from the chamber. More easily, the N.sub.2 O can be displaced with nitrogen to provide a nitrogen atmosphere, reducing the concentration of N.sub.2 O satisfactorily, and the hydrogen nitride can be introduced subsequently.
The durations of the heat treatments in the N.sub.2 O and hydrogen nitride atmospheres depend on the characteristics of the silicon oxide film, the heat treatment temperature and the intensity of the ultraviolet light, for example, but, in consideration of mass production, they are preferably from 30 minutes to 6 hours. Furthermore, the rates of raising and lowering the substrate temperature in the heat treatment processes should be determined for the execution of the invention but, in consideration of mass production, the rates at which the temperature is raised and the cooling rates are preferably from 5 to 30 raising of the temperature and cooling may be carried out in a nitrogen atmosphere.
The fourth invention involves carrying out the heat treatment of a silicon oxide film which has been accumulated on an active layer, by means of a CVD method or a PVD method, at 300-700 500-600 ultraviolet light and then replacing the atmosphere with an N.sub.2 O atmosphere and carrying out a heat treatment at 300-700 preferably at 500-600 with ultraviolet light. At this time the wavelength of the ultraviolet light used is 100-350 nm, and preferably 150-300 nm.
The same precautions as in the third invention described above must be taken when changing the atmosphere from hydrogen nitride to N.sub.2 O in the process described above. Furthermore, the raising and lowering of the temperature and the irradiation and interruption of the irradiation with ultraviolet light should be controlled in the same way as in the third invention. The durations of the heat treatments are also the same.
In this present invention, for example, the sputter method should be used as the PVD method and the plasma CVD method, the low pressure CVD method or the atmospheric pressure CVD method should be used as the CVD method. Other methods of film formation can also be used. Furthermore, methods in which TEOS is used as a raw material can also be used in the plasma CVD method or the low pressure CVD method. In the former case TEOS and oxygen are used for the raw material gas and the accumulation should be carried out at a substrate temperature of 200-500 silicon oxide film which is undamaged by the plasma can be obtained at a comparatively low temperature (for example at 375 C.) using TEOS and ozone as raw materials.
Similarly, with the low pressure CVD method it is possible to reduce plasma damage of the active layer if monosilane (SiH.sub.4) and oxygen gas (O.sub.2) are used as the principal raw materials. Furthermore, the ECR-CVD method in which a discharge under ECR (electron cyclotron resonance) conditions is used from among the plasma CVD methods gives rise to less damage by the plasma and so it is possible to form even better gate insulating films.
A reaction chamber which has a device with which the atmosphere can be controlled and a device for ultraviolet light irradiation is required for the execution of the third and fourth inventions described above. In practical terms, this is heat treatment apparatus which is characterized by having a chamber for heat treatment, a standby chamber in which the substrates are held before carrying out the heat treatment and the substrates are held after carrying out heat treatment, and a front chamber which is furnished with a transporting device for moving the substrate, in that a substrate holder which is furnished with a heater which heats the substrate is provided in the chamber for heat treatment, and in that a light source for irradiating the substrate with ultraviolet light is provided outside or inside the chamber for heating the aforementioned substrates. Furthermore, it may have a plurality of chambers so that the heat treatment in an N.sub.2 O atmosphere and the heat treatment in a hydrogen nitride atmosphere can be carried out in different chambers.
When a silicon oxide film which has been formed by means of a CVD method or a PVD method is heat treated in an N.sub.2 O atmosphere at a temperature of 900 and the Si--H bonds and Si--OH bonds in the silicon oxide film are converted to the nitride or the oxide, becoming Si.tbd.N or Si.sub.2 ═N--O bonds, and the hydrogen content in the silicon oxide film is reduced. These reactions are liable to proceed in particular at the boundary between the silicon oxide and silicon and, as a result, the nitrogen is concentrated at the silicon oxide/silicon boundary. The amount of nitrogen which is added and concentrated close to the boundary with such a technique is at least ten times the average concentration in the silicon oxide film. The inclusion of 0.1-10 atom. %, and typically the inclusion of 1-5 atom. %, of nitrogen in the silicon oxide is desirable for a gate insulating film.
Consequently, the unpaired bonds and the Si--H bonds and Si--OH bonds which are weak bonds and easily broken by hot carriers at the boundary between the gate insulating film and the active layer are converted to Si.tbd.SN bonds and Si.sub.2 ═N--O bonds, for example, which are strong bonds, and the extent of any change in the chemical state due to hot carriers is greatly reduced.
Reactions of the type indicated above proceed only on heat treatment at a temperature of at least 900 principally because the temperature required to break down N.sub.2 O is at least 900 irradiation with ultraviolet light is used conjointly. The wavelength of the ultraviolet light used at this time is 100-350 nm, and preferably 150-300 nm. It has been concluded that this is because a high temperature as described above is not required since the N.sub.2 O is broken down by the ultraviolet light, and the same reactions as indicated above can proceed even on heat treatment at 300-700 500-600 unpaired bonds in particular in a silicon oxide film which is being irradiated with ultraviolet light readily absorb the ultraviolet light and, as a result, a state of chemical excitation arises in these parts, and it is thought that this also promotes chemical reaction. The facts indicated above have been readily verified by means of the experiments described below.
Samples where a silicon oxide film had been formed with a thickness of 1200 Å using the plasma CVD method with TEOS and oxygen as raw materials on a silicon wafer were used in the experiments. The sample was heat treated in an N.sub.2 O atmosphere while being irradiated with ultraviolet light and the nitrogen concentration was then investigated using the secondary ion mass spectroscopy (SIMS) method. The results obtained are shown in FIG. 9. Here, FIG. 9(A) is the concentration profile in the depth direction of a sample which had been heat treated for 3 hours at 400 ultraviolet light. For comparison, the concentration profile in the depth direction of the sample before annealing is shown in FIG. 9(B).
From this analysis it is confirmed that on looking at a sample which has been annealed at 400 the conjoint use of irradiation with ultraviolet light shown in FIG. 9(A), the nitrogen concentration at the boundary between the silicon oxide and the silicon is higher by an order of magnitude when compared with the sample before carrying out the anneal.
Moreover, the unpaired bonds of the silicon are difficult to convert to nitride or oxide with the abovementioned ultraviolet light irradiation and heat treatment in an N.sub.2 O atmosphere. By heat treating at a suitable temperature (300-700 atmosphere of hydrogen or a hydrogen nitride, such as ammonia (NH.sub.3) or hydrazine (N.sub.2 H.sub.4) for example, the unpaired bonds Si. may be converted to Si--H bonds in order to promote reaction. The reaction is facilitated if irradiation with ultraviolet light is carried out at this time. Stable bonds can then be obtained by means of the reaction described above if heat treatment in an N.sub.2 O atmosphere/ultraviolet irradiation process is carried out subsequently. Moreover, on treatment in a hydrogen nitride atmosphere, the Si--H bonds and Si═O bonds are converted to the nitride and form Si N or Si--N═H.sub.2 bonds.
The effect is especially pronounced in those cases where the invention is applied to silicon oxide films which have been formed using the sputter method (and especially the silicon oxide films in which the oxygen concentration is less than the stoichiometric ratio obtained with argon, for example, as the sputter atmosphere). This is because the deficient oxygen can be supplemented by heat treating such a film in an N.sub.2 O atmosphere and the composition of the silicon oxide film can be made to approach the stoichiometric ratio.
A silicon oxide film which has been formed using a sputter method of this type can be subjected to a heat treatment at a suitable temperature in an atmosphere of hydrogen or a hydrogen nitride, such as ammonia (NH.sub.3) or hydrazine (N.sub.2 H.sub.4) for example, and the unpaired bonds Si. can be converted to Si--H bonds before carrying out the heat treatment in an N.sub.2 O atmosphere. The oxidation by heat treatment in an N.sub.2 O atmosphere is further facilitated by this means.
The facts outlined above show that the formation of silicon oxide films by means of the sputter method is not disadvantageous. That is to say, conventionally, the formation of silicon oxide films by the sputter method has only been carried out under limited atmospheric conditions to provide a composition approaching the stoichiometric ratio. For example, when mixtures of oxygen and argon have been considered for the atmosphere, the condition that oxygen/argon&gt;1 had to be fulfilled and, for preference, it has been desirable that the treatment should be carried out in a pure oxygen atmosphere. Consequently, the rate of film formation has been low and this has not been suitable for mass production. Furthermore, oxygen is a reactive gas and problems have arisen with oxidation of the vacuum apparatus and the chamber for example.
The invention provides a special effect when it is applied to silicon oxide films which have been formed by means of the plasma CVD method using a silicon source which contains carbon, such as TEOS for example. Carbon is included in large amounts in these silicon oxide films, and the carbon which is present at the boundary with the silicon film in particular causes a fall off of the TFT characteristics. Oxidation is promoted by heat treatment in an N.sub.2 O atmosphere in this invention, and the carbon is also oxidized at this time and released from the system as carbon dioxide gas, and so the carbon content of the film can be reduced.
As a result, by making use of the present invention, the hydrogen and carbon concentrations in a silicon oxide film which has been formed by the plasma CVD method with TEOS as a raw material gas can be reduced, and the nitrogen concentration can be increased, while maintaining a low temperature of 300-700 film is used as a gate insulating film exhibit excellent characteristics and high reliability.
When a silicon oxide film which has been formed by means of a CVD method or a PVD method is heat treated in an NH.sub.3 or N.sub.2 H.sub.4 atmosphere at a temperature of 900 up with nitrogen, and the Si--H bonds and Si--OH bonds in the silicon oxide film are converted to the nitride or the oxide, becoming Si.tbd.N or Si.sub.2 ═N--H bonds, and the nitrogen content in the silicon oxide film is increased. In particular, this reaction is liable to proceed at the boundary between the silicon oxide and silicon and, as a result, the nitrogen is concentrated at the silicon oxide-silicon boundary. The amount of nitrogen which is added and concentrated close to the boundary with such a technique is at least ten times the average concentration in the silicon oxide film. The inclusion of 0.1-10 atom. %, and typically the inclusion of 1-5 atom. %, of nitrogen in the silicon oxide is desirable for a gate insulating film.
Consequently, the unpaired bonds and the Si--H bonds and Si--OH bonds which are weak bonds and easily broken by hot carriers at the boundary between the gate insulating film and the active layer are converted to Si.tbd.N bonds and Si.sub.2 ═N--O bonds, for example, which are strong bonds, and the change in the chemical state due to hot carriers is greatly reduced.
Reactions of the type indicated above proceed only with heat treatment at a temperature of at least 900 principally because the temperature required to break down NH.sub.3 and N.sub.2 H.sub.4 is at least 900 reduced if irradiation with ultraviolet light is used conjointly. The wavelength of the ultraviolet light used at this time is 100-350 nm, and preferably 150-300 nm. It has been concluded that this is because such a high temperature as described above is not required since the NH.sub.3 and N.sub.2 H.sub.4 are broken down by the ultraviolet light, and the same reactions as indicated above can proceed even on heat treatment at 300-700 Si--OH bonds, Si--H bonds and the unpaired bonds in particular in a silicon oxide film which is being irradiated with ultraviolet light readily absorb the ultraviolet light and, as a result, a state of chemical excitation arises in these parts, and it is thought that this also promotes chemical reaction.
The effect is especially pronounced in those cases where the invention is applied to silicon oxide films which have been formed using the sputter method (and especially the silicon oxide films in which the oxygen concentration is less than the stoichiometric amount obtained with argon, for example, as the sputter atmosphere). That is to say, such a film has many unpaired bonds but, on heat treating in a hydrogen nitride atmosphere, such as an NH.sub.3 or N.sub.2 H.sub.4 atmosphere at 300-700 irradiating with ultraviolet light, the unpaired bonds are formed into nitrides and nitrogen is bonded instead of the oxygen which is deficient in terms of the stoichiometric ratio, and it is possible to form a silicon oxide film which has few unpaired bonds.
Such effects can also be obtained with silicon oxide films which have been formed with PVD methods other than the sputter method, or with various CVD methods. It is possible by using this invention in this way to reduce the number of unpaired bonds in a silicon oxide film which has been formed using a PVD method or a CVD method and to raise the nitrogen concentration while using a low temperature of 300-700 such a silicon oxide film is used as a gate insulating film exhibit excellent characteristics and high reliability.
If the treatment described in the third invention is carried out with a silicon oxide film which has been formed with a CVD method or PVD method then the Si--H bonds and Si--OH bonds in the silicon oxide film are converted to nitrides or oxides by the initial heat treatment in an N.sub.2 O atmosphere, and they are converted to Si.tbd.N or Si.sub.2 ═N--O bonds, and the hydrogen content of the silicon oxide film is reduced.
The effect of the irradiation with ultraviolet light (wavelength 100-350 nm, and preferably 150-300 nm) in this present invention is very great. That is to say, the abovementioned reactions do not proceed at all in the absence of irradiation with ultraviolet light. A temperature of at least 900 heat treatment. That is to say, this is because the temperature required to break down N.sub.2 O or hydrogen nitrides thermally is at least 900
However, the abovementioned reactions can be realized at lower temperatures by irradiating with ultraviolet light. It has been concluded that this is because in the first place such a high temperature as described above is not required since the N.sub.2 O and hydrogen nitrides are broken down by the ultraviolet light, and the same reactions as indicated above can proceed even on heat treatment at 300-700 500-600
Consequently, the unpaired bonds and the Si--H bonds and Si--OH bonds which are weak bonds and easily broken by hot carriers at the boundary between the gate insulating film and the active layer are converted to Si N bonds and Si.sub.2 ═N--O bonds, for example, which are strong bonds, and the change in the chemical state due to hot carriers is greatly reduced.
The effect is especially pronounced in those cases where the invention is applied to silicon oxide films which have been formed using the sputter method (and especially the silicon oxide films in which the oxygen concentration is less than the stoichiometric ratio obtained with argon, for example, as the sputter atmosphere). This is because the deficient oxygen can be supplemented by heat treating such a film in an N.sub.2 O atmosphere and the composition of the silicon oxide film can be made to approach the stoichiometric ratio. The unpaired bonds which are not dealt with by the heat treatment in an N.sub.2 O atmosphere are converted to nitride by means of a subsequent heat treatment in a hydrogen nitride atmosphere.
If a treatment as described in the fourth invention is carried out with a silicon oxide film which has been formed using a CVD method or a PVD method then the unpaired bonds, Si--H bonds and Si--OH bonds in the silicon oxide film are converted to nitride by the initial heat treatment in a hydrogen nitride atmosphere and converted to Si.tbd.N or Si--N═H.sub.2 bonds.
Moreover, the nitrogen hydride groups (NH.sub.2 groups for example), which are formed in the abovementioned reaction are converted to nitride or oxide by the succeeding heat treatment in an N.sub.2 O atmosphere and form Si.tbd.N bonds and Si.sub.2 ═N--O bonds for example. The effect of the irradiation with ultraviolet light in the abovementioned reactions is very great, as in the case of the third invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 This illustrative example is an example in which a silicon oxide film which has been formed with a plasma CVD method is modified by means of a heat treatment in an N.sub.2 O atmosphere while being irradiated with ultraviolet light and in which an N-channel TFT is formed using this as a gate insulating film. The manufacturing process of the TFT in this example is shown in FIG. 7, and an outline of the apparatus used for the heat/ultraviolet irradiation treatment of the silicon oxide film mentioned above is shown in FIG. 1.
First of all, the silicon oxide film 702 base was formed with a thickness of 3000 Å using the plasma CVD method on the substrate 701. Then, an amorphous silicon film was formed with a thickness of 500 Å using the plasma CVD method. After this, a heat treatment was carried out in an N.sub.2 atmosphere and the amorphous silicon film was crystallized. A trace amount of an element which promotes the crystallization of amorphous silicon, such as nickel for example, may be added in order to promote the crystallization of the amorphous silicon at this time. Furthermore, laser annealing may be used to improve crystallization. (FIG. 7(A))
In method 1, the film was formed with the plasma CVD method using TEOS as a raw material. The TEOS which had been vaporized in a vaporizer and oxygen were introduced into a chamber which had parallel plate-type electrodes, RF power (for example, frequency 13.56 MHz) was introduced and a plasma was formed, and the accumulation was made at a substrate temperature of 200-500 illustrative example the reaction pressure was 4 Pa, the power input was 150 W and the substrate temperature was set at 350
Method 2 was the sputter method. In this case synthetic quartz was used for the target and the film was formed by sputtering in a 100% oxygen atmosphere at a pressure of 1 Pa. The power input was 350 W and the substrate temperature was set at 200
Method 3 was the ECR-CVD method, and oxygen and monosilane (SiH.sub.4) were used as the raw material gases. Nitrogen oxides, such as N.sub.2 O, NO and NO.sub.2 for example, could be used in place of the oxygen. Furthermore, the film forming conditions at this time were a microwave power input (frequency 2.45 MHz) of 400 W without heating the substrate.
Subsequently, heat treatments were carried out in an N.sub.2 O atmosphere using the heat treatment apparatus shown in FIG. 1. As shown in FIG. 1, the heat treatment apparatus used in this illustrative example was constructed with a chamber 101 for carrying out the heat treatment, a standby chamber 102 in which the substrate was held before treatment, a standby chamber 103 in which the substrate was held after treatment and a front chamber 109 which was furnished with the transporting device 110, and the substrate 111 was moved between these chambers by means of the transporting device 110. Moreover, in this illustrative example a single substrate type system with which one substrate was treated at a time was used in the chamber 101.
Then, N.sub.2 O gas was introduced into the chamber 101 via the gas supply system 107 and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% N.sub.2 O atmosphere with the pressure inside the chamber set to atmospheric pressure. At this time the heating temperature was 350-600 to 500 hours, and the heat treatment was carried out, for example, for 3 hours.
The heat treatment of the present invention was carried out in the way outlined above and, as a result, an effect similar to that obtained on carrying out a heat treatment at 900 was obtained by means of a heat treatment at 500
No change was observed in the nitrogen, hydrogen and carbon concentrations when silicon oxide films which had been formed using the methods 1-3 described above were heated in the apparatus shown in FIG. 1 under the same temperature conditions in an atmosphere of nitrogen instead of N.sub.2 O for comparison.
After this, an impurity (phosphorus in this case) was implanted into the island-like silicon film 704 by means of the ion doping method, with self-arrangement, using the gate electrode 706 as a mask. The extent of doping in this case was 1 and the accelerating voltage was 10--90 kV and, for example, the extent of doping was set to 1 voltage was set to 80 kV. The N-type impurity regions 707 were formed as a result of this procedure. (FIG. 7(C))
Moreover, activation of the doped impurity regions 707 was carried out by irradiation with a KrF excimer laser (wavelength 248 nm, pulse width 20 nsec). The appropriate energy density of the laser was 200-400 mJ/cm.sup.2, and preferably 250-300 mJ/cm.sup.2. This process could also have been carried out by means of a heat treatment.
The deterioration of the TFT produced in this illustrative example was evaluated. The TFT manufacturing process was just the same in all cases except that the method of preparing the gate insulating film (any of the methods 1-3) and the method of heat treating the gate insulating film (N.sub.2 O atmosphere/ultraviolet light irradiation/500 (the abovementioned conditions are denoted by "N.sub.2 O atmosphere") or N.sub.2 atmosphere/no ultraviolet light irradiation/500 (the abovementioned conditions are denoted by "N.sub.2 atmosphere")) were varied as indicated in the table below. The TFT obtained were set to a drain voltage of +14 V and the gate voltage was varied from -17 V to +17 V, and the drain current was measured. The measurement was made ten times, the electric field effect mobility μ.sub.10 obtained by measurement on the tenth occasion was compared with the electric field effect mobility μ.sub.o obtained on the initial measurement and the value 1-(μ.sub.10 /μ.sub.o) was defined as the deterioration factor. The results obtained are shown in the table below. (A minus sign for the deterioration factor signifies that the mobility had increased.)
With all of the samples it is clear that the deterioration factor was greatly reduced by irradiating with ultraviolet light when carrying out the heat treatment in an N.sub.2 O atmosphere of this present invention. Furthermore, it was also clear from a similar experiment that no improvement was seen in the deterioration factor if there was no irradiation with ultraviolet light when carrying out the heat treatment in an N.sub.2 O atmosphere.
The TFT which had been manufactured in this illustrative example had good durability and little deterioration even though a silicon oxide film which had been prepared using a PVD method or a CVD method was used for the gate insulating film, and TFT which had excellent characteristics were obtained. This is due to the fact that the amounts of carbon and hydrogen in the silicon oxide film were reduced and the amount of nitrogen was increased by the heat treatment carried out with the conjoint use of ultraviolet light irradiation carried out in an N.sub.2 O atmosphere in accordance with the present invention.
The method of treatment using this apparatus will now be described. First of all the substrates 203 were set around the inner wall of the chamber 201 in such a way as to surround the ultraviolet light source 204. Then, N.sub.2 gas was introduced into the chamber 201 from the gas supply system and the interior of the chamber was displaced with N.sub.2. At this time, gas was evacuated via the evacuating system 206 and a constant pressure was generally maintained within the chamber.
Next, after displacing the interior of the chamber with N.sub.2, the heaters were heated and ultraviolet irradiation was carried out. At this time the heating temperature was 300-700 example, to 500
After heating the substrates to the prescribed temperature, the N.sub.2 was replaced with N.sub.2 O and irradiation with ultraviolet light was carried out. At this time, the duration of the treatment was from 30 minutes to 6 hours, and the treatment was carried out, for example, for 4 hours.
Furthermore, the exhausting systems 412 and 413 for evacuating gas and the gas supply systems 409, 410 and 411 for supplying gas were established in the chamber 301. In this illustrative example, gas supply systems were established for each part so that an N.sub.2 atmosphere was established in the parts 403 and 405 where the substrate was being heated up and cooled down and an N.sub.2 O atmosphere was established in the part 404 where the substrate was being heated at a constant temperature and irradiated with ultraviolet light. Moreover, the exhausting systems 412 and 413 were established in the vicinities of the boundaries between these zones for evacuating the gases which had been introduced. Mixing of the gases in each zone was prevented by the establishment of the exhausting systems 412 and 413 in the boundary regions.
Then the substrates were moved into the heating process, and the temperature gradient along the conveyor 401 was as shown in FIG. 4(C). First of all the substrates were heated at a rate of 5-30 for example at 10 N.sub.2 was being introduced from the gas supply system 409 and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, the substrates were moved into the zone 404 which was being heated to a constant temperature. The heat treatment was carried out here while the substrates were being irradiated with ultraviolet light from the ultraviolet light source which had been established over the conveyor. The heating temperature was 500-600 550 at this time and an N.sub.2 O atmosphere was provided. Furthermore, twenty substrates could be treated at the same time in the zone 404. Furthermore, the time required for one substrate to pass through this zone, which is to say the time required to heat treat one substrate, was from 30 minutes to 6 hours, and it is set, for example, to 3 hours.
After carrying out the heat treatment in this way, the substrate was cooled to 250 was 5-30 example, to 10 the gas supply system 411 at this time and an N.sub.2 atmosphere was provided.
Heat treatment in an N.sub.2 O atmosphere with the conjoint use of ultraviolet irradiation was carried out in this way and, while the time required to treat one substrate in the apparatus shown in Example 1 was about 4 hours, it was about 10 minutes when the apparatus shown in this example was used, and the productivity was increased.
The heat treatment of this invention was carried out in the way described above. The results obtained on analysis using secondary ion mass spectroscopy (SIMS) were that the amount of nitrogen in the silicon oxide film, especially at the boundary with the silicon film, was increased as a result of the heat treatment carried out with the conjoint use of ultraviolet light, and it was observed that the carbon and hydrogen concentrations were reduced. This was the same effect as that obtained on carrying out heat treatment at 900
Furthermore, the gas supply system 605 was established in the chamber 501 so as to provide an N.sub.2 atmosphere when the substrates were being heated and cooled and to provide an N.sub.2 O atmosphere when they were being heated at a constant temperature. Moreover, the exhausting system 606 was established for exhausting the gas which had been introduced. Furthermore, the light source 605 was established for irradiating the substrates with ultraviolet light. A low pressure mercury lamp (center wavelength 246 nm and 185 nm) was used for the ultraviolet light source in this illustrative example.
The way in which the temperature changed with time during the heat treatment is shown in FIG. 6(C). The substrates were heated at a rate of 5-30 temperature was being raised. N.sub.2 gas was being introduced from the gas supply system 605 at this time and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, when the temperature at which the heat treatment was to be carried out was reached, ultraviolet light was irradiated from the ultraviolet light source 604 which was established above the conveyor 601. The heating temperature was 500-600 out, for example, to 550 introduced by means of the gas supply system 605 immediately before the temperature at which the heat treatment was to be carried out had been reached and, when the temperature at which the heat treatment was to be carried out was reached, the situation was such that the heat treatment was carried out in a completely N.sub.2 O atmosphere. The heat treatment time was from 30 minutes to 6 hours, and it was set, for example, at 4 hours.
After carrying out the heat treatment in this way the substrates were cooled to 250 C./min, the same as when heating, and it was set, for example, to 10 system 605 at this time and an N.sub.2 atmosphere was provided.
A heat treatment of this invention was carried out in this way. By means of the treatment described above, it was confirmed by means of secondary ion mass spectroscopy (SIMS) that a similar amount of nitrogen was contained in the silicon oxide film as that obtained on carrying out a heat treatment at 900
EXAMPLE 5 This illustrative example is an example in which silicon oxide films which had been formed on silicon films by means of the low pressure CVD method with monosilane (SiH.sub.4) and oxygen gas (O.sub.2) as raw materials were heat treated using the heat treatment apparatus shown in FIG. 2. The conditions for the formation of the silicon oxide films used in this illustrative example were substrate temperature 300-500 pressure within the chamber of 0.1-10 torr, these being set, for example to 400
First of all the substrates 203 were set around the inner wall of the chamber 201 in such a way as to surround the ultraviolet light source 204. Then, N.sub.2 gas was introduced into the chamber 201 from the gas supply system and the interior of the chamber was displaced with N.sub.2. At this time, gas was evacuated via the evacuating system 206, and a constant pressure was generally maintained within the chamber.
Next, after displacing the interior of the chamber with N.sub.2, the heaters were heated and ultraviolet irradiation was carried out. At this time, the heating temperature was 300-700 example, to 500
After heating the substrates to the prescribed temperature, the N.sub.2 was replaced with N.sub.2 O and irradiation with ultraviolet light (center wavelength 246 nm and 185 nm) was carried out. At this time, the duration of the treatment was from 30 minutes to 6 hours, and heat treatment was carried out, for example, for 3 hours.
EXAMPLE 6 This illustrative example is an example in which a silicon oxide film which has been formed with a plasma CVD method is modified by means of a heat treatment in an NH.sub.3 atmosphere while being irradiated with ultraviolet light and in which an N-channel TFT is formed using this as the gate insulating film. The manufacturing process of the TFT in this example is shown in FIG. 7, and an outline of the apparatus used for the heat/ultraviolet irradiation treatment of the silicon oxide film mentioned above is shown in FIG. 1.
In method 1, the film was formed with the plasma CVD method using TEOS as a raw material. The TEOS, which had been vaporized in a vaporizer, and oxygen were introduced into a chamber which had parallel plate-type electrodes, RF power (for example, frequency 13.56 MHz) was introduced and a plasma was formed, and the accumulation was carried out at a substrate temperature of 200-500 this illustrative example the reaction pressure was 4 Pa, the power input was 150 W and the substrate temperature was set at 350
Method 3 was the ECR-CVD method, and oxygen and monosilane (SiH.sub.4) were used as the raw material gases. Nitrogen oxides, such as N.sub.2 O, NO and NO.sub.2 for example, could be used in place of the oxygen. Furthermore, the film-forming conditions at this time were a microwave power input (frequency 2.45 MHz) of 400 W without substrate heating.
Subsequently, heat treatments were carried out in an NH.sub.3 atmosphere using the heat treatment apparatus shown in FIG. 1. As shown in FIG. 1, the heat treatment apparatus used in this illustrative example was constructed with the chamber 101 for carrying out the heat treatment, the standby chamber 102 in which the substrate was held before treatment, the standby chamber 103 in which the substrate was held after treatment and the front chamber 109 which was furnished with the transporting device 110, and the substrate 111 was moved between these chambers by means of the transporting device 110. Moreover, in this illustrative example a single plate-type system with which one plate was treated at a time was used in the chamber 101.
Then, NH.sub.3 gas was introduced into the chamber 101 via the gas supply system 107 and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% NH.sub.3 atmosphere with the pressure inside the chamber set to atmospheric pressure. At this time the heating temperature was 350-600 to 500 hours, and heat treatment was carried out, for example, for 3 hours.
No change was observed in the nitrogen concentration when silicon oxide films which had been formed using the methods 1-3 described above were heated in the apparatus shown in FIG. 1 under the same temperature conditions in an atmosphere of nitrogen instead of NH.sub.3 for comparison.
After this, an impurity (phosphorus in this case) was implanted into the island-like silicon film 704 with the ion doping method, with self-arrangement, using the gate electrode 706 as a mask. The extent of doping in this case was 1 atom/cm.sup.2, the accelerating voltage was 10-90 kV and, for example, the extent of doping was set to 1 accelerating voltage was set to 80 kV. The N-type impurity regions 707 were formed as a result of this procedure. (FIG. 7(C))
The deterioration of the TFT produced in this illustrative example was evaluated. The TFT manufacturing process was always the same except that the method of preparing the gate insulating film (any of the methods 1-3) and the method of heat treating the gate insulating film (NH.sub.3 atmosphere/ultraviolet light irradiation/500 abovementioned conditions are denoted by "NH.sub.3 atmosphere") or N.sub.2 atmosphere/no ultraviolet light irradiation/500 abovementioned conditions are denoted by "N.sub.2 atmosphere")) were varied as indicated in the table below. The TFT obtained were set to a drain voltage of +14 V, the gate voltage was varied from -17 V to +17 V and the drain current was measured. The measurement was made ten times, the electric field effect mobility μ.sub.10 obtained by measurement on the tenth occasion was compared with the electric field effect mobility μ.sub.o obtained on the initial measurement, and the value 1-(μ.sub.10 /μ.sub.o) was defined as the deterioration factor. The results obtained are shown in the table below. (A minus sign for the deterioration factor signifies that the mobility had increased.)
With all of the samples it is clear that the deterioration factor was greatly reduced by irradiating with ultraviolet light when carrying out the heat treatment in an NH.sub.3 atmosphere of this present invention. Furthermore, it was also clear from a similar experiment that no improvement was seen in the deterioration factor if there was no irradiation with ultraviolet light when carrying out the heat treatment in an NH.sub.3 atmosphere.
The TFT which had been produced in this illustrative example had good durability and little deterioration even though a silicon oxide film which had been prepared using a PVD method or CVD method was being used for the gate insulating film, and TFT which had excellent characteristics were obtained. This is due to the fact that the unpaired bonds and the Si--H and Si--OH bonds had been converted to nitride and the amount of nitrogen in the silicon oxide film had been increased by the heat treatment with the conjoint use of ultraviolet light irradiation carried out in an NH.sub.3 atmosphere in accordance with the present invention.
An example of treatment using this apparatus will now be described. The substrates 203 were set around the inner wall of the chamber 201 in such a way as to surround the ultraviolet light source 204. Then, N.sub.2 gas was introduced into the chamber 201 from the gas supply system and the interior of the chamber was displaced with N.sub.2. At this time, gas was evacuated via the exhausting system 206, and a constant pressure was generally maintained within the chamber.
Next, after displacing the interior of the chamber with N.sub.2, the heaters were heated and ultraviolet irradiation was started. At this time the heating temperature was 300-700 example, to 500
After heating the substrates to the prescribed temperature, the N.sub.2 was replaced with N.sub.2 H.sub.4 and irradiation with ultraviolet light was carried out. At this time, the duration of the treatment was from 30 minutes to 6 hours, and it was carried out, for example, for 4 hours.
Furthermore, the exhausting systems 412 and 413 for evacuating gas, and the gas supply systems 409, 410 and 411 for supplying gas, were established in the chamber 301. In this illustrative example, gas supply systems were established for each part so that an N.sub.2 atmosphere was established in the parts 403 and 405 where the substrate was being heated up and cooled down and an NH.sub.3 atmosphere was established in the part 404 where the substrate was being heated at a constant temperature while being irradiated with ultraviolet light. Moreover, the exhausting systems 412 and 413 were established in the vicinities of the boundaries between these zones for evacuating the gases which had been introduced. Mixing of the gases in each zone was prevented by the establishment of the exhausting systems 412 and 413 in the boundary regions.
Then, they were moved into the heating process and the temperature gradient along the conveyor 401 was as shown in FIG. 10(C). First of all the substrates were heated at a rate of 5-30 rate of 10 was being introduced from the gas supply system 409 and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, the substrates were moved into the zone 404 which was being heated to a constant temperature. The heat treatment was carried out here while irradiating with ultraviolet light from the ultraviolet light source which had been established over the conveyor. The heating temperature was 500-600 was supplied from the gas supply system 410 at this time and an NH.sub.3 atmosphere was provided. Moreover, twenty substrates could be treated at the same time in the zone 404. Furthermore, the time required for one substrate to pass through this zone, which is to say the time required to heat treat one substrate, was from 30 minutes to 6 hours, and it was set, for example, to 3 hours.
After carrying out heat treatment in this way, the substrates were cooled to 250 was 5-30 example, to 10 the gas supply system 411 at this time and an N.sub.2 atmosphere was provided.
Heat treatment in an NH.sub.3 atmosphere with the conjoint use of ultraviolet irradiation was carried out in this way, and while the time required to treat one substrate in the apparatus shown in Example 1 was about 4 hours, it was about 10 minutes when the apparatus shown in this illustrative example was used and the productivity was increased.
The heat treatment of this invention was carried out in the way described above. The result obtained on analysis using secondary ion mass spectroscopy (SIMS) showed that the amount of nitrogen in the silicon oxide film, especially at the boundary with the silicon film, was increased. This was the same effect as that obtained on heat treating at 900
EXAMPLE 9 This illustrative example is an example in which silicon oxide films which had been formed on a silicon film by means of the ECR-CVD method using monosilane (SiH.sub.4) and oxygen as the raw material gases are heat treated using the heat treatment apparatus shown in FIG. 5. The silicon oxide films used in this illustrative example were formed by means of method 3 for the silicon oxide film 705 (see FIG. 7(B)) of Illustrative Example 1.
Furthermore, the gas supply system 605 was established in the chamber 501 so as to provide an N.sub.2 atmosphere when the substrates were being heated and cooled and to provide an N.sub.2 H.sub.4 atmosphere when they were being heated at a constant temperature. Moreover, the exhausting system 606 was established for evacuating the gas which had been introduced. Furthermore, the light source 605 is established to irradiate the substrates with ultraviolet light.
The way in which the temperature changed with time during heat treatment is shown in FIG. 11(C). The substrates were heated at a rate of 5-30 C./min, for example at a rate of 10 period. N.sub.2 gas was being introduced from the gas supply system 605 at this time and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, when the temperature at which the heat treatment was to be carried out was reached, ultraviolet light was irradiated from the ultraviolet light source 604 which was established above the conveyor 601. The heating temperature was 500-600 out, for example, at 550 introduced by means of the gas supply system 605 immediately before the temperature at which the heat treatment was to be carried out had been reached, and when the temperature at which the heat treatment was to be carried out was reached the situation was such that the heat treatment was carried out in a completely N.sub.2 H.sub.4 atmosphere. The heat treatment time was from 30 minutes to 6 hours, and it was set, for example, to 4 hours.
After carrying out the heat treatment in this way the substrates were cooled to 250 C./min, the same as when heating, and it was set, for example, to 10 system 605 at this time and the cooling was carried out in an N.sub.2 atmosphere.
EXAMPLE 10 This illustrative example is an example in which silicon oxide films which had been formed on silicon films by means of the low pressure CVD method with monosilane (SiH.sub.4) and oxygen gas (O.sub.2) as raw materials are heat treated using the heat treatment apparatus shown in FIG. 5. The conditions for the formation of the silicon oxide film used in this illustrative example were substrate temperature 300-500 pressure within the chamber of 0.1-10 torr, these being set, for example to 400
Subsequently, when the temperature at which the heat treatment was to be carried out was reached, ultraviolet light was irradiated from the ultraviolet light source 604 (center wavelength 246 nm, 185 nm) which was established above the conveyor 601. The heating temperature was 500-600 550 the gas supply system 605 immediately before the temperature at which the heat treatment was to be carried out had been reached, and when the temperature at which the heat treatment was to be carried out was reached the situation was such that the heat treatment was carried out in a completely N.sub.2 H.sub.4 atmosphere. The heat treatment time was from 30 minutes to 6 hours, and it was set, for example, to 3 hours.
After carrying out the heat treatment in this way, the substrates were cooled to 250 C./min, the same as when heating, and it was set, for example, to 10 system 605 at this time and the cooling was carried out in an N.sub.2 atmosphere.
A heat treatment of this invention was carried out in this way. By means of the treatment described above, it was confirmed by means of secondary ion mass spectroscopy (SIMS) that a similar amount of nitrogen was contained in the silicon oxide film to that obtained on carrying out a heat treatment at 900
EXAMPLE 11 This illustrative example provides an example in which the third and fourth inventions are executed. That is to say, it is an example in which a silicon oxide film was heat treated in an N.sub.2 O atmosphere while being irradiated with ultraviolet light, and then the film quality was improved by carrying out a heat treatment in a hydrogen nitride atmosphere (an ammonia atmosphere in this illustrative example), and an N-channel-type TFT was formed using this as a gate insulation film, and an example in which a silicon oxide film was heat treated in a hydrogen nitride atmosphere (an ammonia atmosphere in this illustrative example) while being irradiated with ultraviolet light, and then the film quality was improved by carrying out a heat treatment in an N.sub.2 O atmosphere, and an N-channel-type TFT was formed using this as a gate insulation film. Furthermore, an outline of the apparatus which was used for the abovementioned heat/ultraviolet light irradiation treatment is shown in FIG. 1.
In method 1, the film was formed with the plasma CVD method using TEOS as a raw material. The TEOS which had been vaporized in a vaporizer and oxygen were introduced into a chamber which had parallel plate-type electrodes, RF power (for example, frequency 13.56 MHz) was introduced and a plasma was formed, and the accumulation was carried out at a substrate temperature of 200-500 this illustrative example the reaction pressure was 4 Pa, the power input was 150 W and the substrate temperature was set at 350
Then, N.sub.2 O gas was introduced into the chamber 101 via the gas supply system 107 and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% N.sub.2 O atmosphere with the pressure inside the chamber set to atmospheric pressure. At this time, the heating temperature was 350-600 to 500 hours, and heat treatment was carried out for, for example, 3 hours.
Subsequently, the N.sub.2 O was evacuated from the chamber and NH.sub.3 was introduced. At this time, the introduction of the NH.sub.3 was carried out after evacuation of the N.sub.2 O had been carried out satisfactorily and it was at a low concentration. NH.sub.3 was introduced in this way and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% NH.sub.3 atmosphere with the pressure inside the chamber set to atmospheric pressure. At this time, the heating temperature was 500
First of all NH.sub.3 gas was introduced into the chamber 101 via the gas supply system 107 and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% NH.sub.3 atmosphere with the pressure inside the chamber set to atmospheric pressure. At this time the heating temperature was 500 carried out for a treatment time of 3 hours.
Subsequently, the NH.sub.3 was evacuated from the chamber and N.sub.2 O was introduced. At this time the introduction of the N.sub.2 O was carried out after evacuation of the NH.sub.3 had been carried out satisfactorily and it was at a low concentration. N.sub.2 O was introduced in this way and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% N.sub.2 O atmosphere with the pressure inside the chamber set to atmospheric pressure. At this time the heating temperature was 500 time of 3 hours.
No change was observed in the nitrogen, hydrogen and carbon concentrations when the silicon oxide films which had been formed using the methods 1-3 described above were heated in the apparatus shown in FIG. 1 under the same temperature conditions in an atmosphere of nitrogen instead of N.sub.2 O or NH.sub.3 for comparison.
After this, an impurity (phosphorus in this case) was implanted into the island-like silicon film 704 with the ion doping method, with self-arrangement using the gate electrode 706 as a mask. The extent of doping in this case was 1 atom/cm.sup.2, the accelerating voltage was 10-90 kV and, for example, the extent of doping was set to 1 accelerating voltage was set to 80 kV. The N-type impurity regions 707 were formed as a result of this procedure. (FIG. 7(C))
The deterioration of the TFT produced in this illustrative example was evaluated. The TFT manufacturing process was always the same except that the method of preparing the gate insulating film (any of the methods 1-3) and the method of heat treating the gate insulating film of the third invention (N.sub.2 O atmosphere+NH.sub.3 atmosphere/ultraviolet light irradiation/500 denoted by "N.sub.2 O/NH.sub.3 atmosphere")) or the method of heat treating the gate insulating film of the fourth invention (NH.sub.3 atmosphere+N.sub.2 O atmosphere/ultraviolet light irradiation/500 C./3 hours (the abovementioned conditions are denoted by "NH.sub.3 /N.sub.2 O atmosphere"), or N.sub.2 atmosphere/no ultraviolet light irradiation/500 denoted by "N.sub.2 atmosphere")) were varied as indicated in the table below. The TFT obtained were set to a drain voltage of +14 V, the gate voltage was varied from -17V to +17 V and the drain current was measured. The measurement was made ten times, the electric field effect mobility μ.sub.10 obtained by measurement on the tenth occasion was compared with the electric field effect mobility μ.sub.o obtained on the initial measurement, and the value 1-(μ.sub.10 /μ.sub.o) was defined as the deterioration factor. The results obtained are shown in the table below. (A minus sign for the deterioration factor signifies that the mobility had increased.)
With all of the samples it is clear that the deterioration factor was greatly reduced by a process of irradiating with ultraviolet light when carrying out the heat treatment in an N.sub.2 O atmosphere and then irradiating with ultraviolet light while carrying out a heat treatment in an NH.sub.3 atmosphere, or conversely by a process of irradiating with ultraviolet light when carrying out the heat treatment in an NH.sub.3 atmosphere and then irradiating with ultraviolet light while carrying out a heat treatment in an N.sub.2 O atmosphere, of this present invention. Furthermore, it was also clear that no reducing effect on the deterioration factor was seen on carrying out a heat treatment and ultraviolet light irradiating treatment in an N.sub.2 atmosphere.
Furthermore, it was also clear from similar experiments that there was no improvement in the deterioration factor if ultraviolet light was not irradiated while the heat treatment was being carried out in the N.sub.2 O atmosphere or NH.sub.3 atmosphere.
The TFT which had been produced in this illustrative example had good durability and little deterioration even though a silicon oxide film which had been prepared using a PVD method or CVD method was being used for the gate insulating film, and TFT which had excellent characteristics was obtained. This is due to the fact that amounts of carbon and hydrogen in the silicon oxide film had been reduced and the nitrogen had been increased by the heat treatment with the conjoint use of ultraviolet light irradiation carried out in an NH.sub.3 atmosphere following the carrying out of a heat treatment with the conjoint use of ultraviolet irradiation in an N.sub.2 O atmosphere, or by the heat treatment with the conjoint use of ultraviolet light irradiation carried out in an N.sub.2 O atmosphere following by the carrying out of a heat treatment with the conjoint use of ultraviolet irradiation in an NH.sub.3 atmosphere, in accordance with the present inventions.
The method of treatment using this apparatus will now be described. First of all the substrates 203 were set around the inner wall of the chamber 201 in such a way as to surround the ultraviolet light source 204. Then N.sub.2 gas was introduced into the chamber 201 from the gas supply system and the interior of the chamber was displaced with N.sub.2. At this time, gas was evacuated via the exhausting system 206 and a constant pressure was generally maintained within the chamber.
Next, after displacing the interior of the chamber with N.sub.2, the heaters were heated and ultraviolet irradiation was started. At this time the heating temperature was 300-700 500
After heating the substrates to the prescribed temperature, the N.sub.2 was replaced with N.sub.2 H.sub.4 and irradiation with ultraviolet light was carried out. At this time, the duration of the treatment was from 30 minutes to 6 hours, and it was carried out, for example, for 2 hours.
After this, N.sub.2 was again introduced into the chamber and the N.sub.2 H.sub.4 was displaced by N.sub.2. Then, the N.sub.2 was displaced with N.sub.2 O and a second heat treatment was carried out with irradiation with ultraviolet light. At this time, the heating temperature was 500 of 2 hours.
Furthermore, the exhausting systems 412 and 413 for evacuating gas and the gas supply systems 409, 410 and 411 for supplying gas were established in the chamber 301. In this illustrative example, gas supply systems were established for each part so that an N.sub.2 atmosphere was established in the parts 403 and 405 where the substrates were being heated up and cooled down and an N.sub.2 O or hydrogen nitride atmosphere was established in the part 404 where the substrates were being heated at a constant temperature and irradiated with ultraviolet light. Moreover, the exhausting systems 412 and 413 were established in the vicinities of the boundaries between these zones for evacuating the gases which had been introduced. Mixing of the gases in each zone was prevented by the establishment of the exhausting systems 412 and 413 in the boundary regions.
Then they were moved into the heating process, and the temperature gradient along the conveyor 401 was as shown in FIG. 4(C). First of all, the substrates were heated at a rate of 5-30 rate of 10 was being introduced from the gas supply system 409 and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, the substrates were moved into the zone 404 which was being heated to a constant temperature. The heat treatment was carried out here while the substrates were being irradiated with ultraviolet light from the ultraviolet light source which had been established over the conveyor. The heating temperature was 500-600 550 at this time and an N.sub.2 O atmosphere was provided. Moreover, twenty substrates could be treated at the same time in the zone 404. Furthermore, the time required for one substrate to pass through this zone, which is to say the time required to heat treat one substrate, was from 30 minutes to 6 hours, and it is set, for example, to 3 hours.
Subsequently, the substrates with which the first substrate treatment process had been completed were set once again in the standby chamber 302 and a heat treatment was carried out. The heating process was carried out in the same way as in the earlier process. Thus, the substrates were heat treated while being irradiated with ultraviolet light from the ultraviolet light source which had been established over the conveyor when they had been moved into the zone 404 which had been heated to a constant temperature. The heating temperature was set at 550 time NH.sub.3 was being introduced from the gas supply system 410 and an NH.sub.3 atmosphere was provided.
After carrying out the heat treatment in this way, the substrates were cooled to 250 time was 5-30 for example, to 10 from the gas supply system 411 at this time and an N.sub.2 atmosphere was provided.
Heat treatment in an NH.sub.3 atmosphere with the conjoint use of ultraviolet light irradiation was carried out after heat treatment in an N.sub.2 O atmosphere with the conjoint use of ultraviolet light irradiation had been carried out in this way, and while about 7 hours was required to treat one substrate in the apparatus shown in Example 1, only about 20 minutes was required when the apparatus shown in this illustrative example was used, and the productivity was increased.
The heat treatment of this invention was carried out in the way described above. The results obtained on analysis using secondary ion mass spectroscopy (SIMS) were that the amount of nitrogen in the silicon oxide film, especially at the boundary with the silicon film, was increased as a result of the heat treatment carried out with the conjoint use of ultraviolet light, and it was observed that the carbon and hydrogen concentrations were reduced. This was the same effect as that obtained on heat treating at 900
Furthermore, the gas supply system 605 is established in the chamber 501 for providing an N.sub.2 atmosphere when the substrates are being heated and cooled and an N.sub.2 O or hydrogen nitride atmosphere when they are being heated at a constant temperature. Moreover, the exhausting system 606 is established for evacuating the gas which has been introduced. Furthermore, the light source 605 is established for irradiating the substrates with ultraviolet light. A low pressure mercury lamp (center wavelength 246 nm and 185 nm) was used for the ultraviolet light source in this illustrative example.
The way in which the temperature changed with time during heat treatment is shown in FIG. 6(C). The substrates were heated at a rate of 5-30 C./min, for example at a rate of 10 period. N.sub.2 gas was being introduced from the gas supply system 605 at this time and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, when the temperature at which the heat treatment was to be carried out was reached, ultraviolet light was irradiated from the ultraviolet light source 604 which was established above the conveyor 601. The heating temperature was 500-600 out, for example, to 550 introduced from the gas supply system 605 immediately before the temperature at which the heat treatment was to be carried out had been reached, and when the temperature at which the heat treatment was to be carried out was reached the situation was such that the heat treatment was carried out in a complete NH.sub.3 atmosphere. The heat treatment time was from 30 minutes to 6 hours, and it was set, for example, to 3 hours.
Subsequently, the NH.sub.3 was displaced with N.sub.2, and then the N.sub.2 was displaced again with N.sub.2 O, and a second heat treatment was carried out. The heat treatment time was set to 3 hours.
A heat treatment of this invention was carried out in this way. It was confirmed by means of secondary ion mass spectroscopy (SIMS) that, by means of the treatment described above, a similar amount of nitrogen was contained in the silicon oxide film as that obtained on carrying out a heat treatment at 900
As shown in FIG. 8, the heat treating apparatus used in this illustrative example had two chambers for carrying out heat treatment, namely the chamber 801 for the exclusive use of an N.sub.2 O atmosphere and the chamber 802 for the exclusive use of a hydrogen nitride (NH.sub.3 in the case of this illustrative example) atmosphere. Furthermore, it was constructed with the standby chamber 803 in which the substrates were held before treatment, the standby chamber 804 in which the substrates were held after treatment and the front chamber 806 which was furnished with the transporting device 805, and the substrates were moved between these chambers by means of the transporting device 805. Moreover, this illustrative example is a batch-type system in which one substrate is treated at a time in the chamber.
Then, N.sub.2 O was introduced into the chamber from the gas supply system 814 and a heat treatment was carried out while irradiating with ultraviolet light in an essentially 100% N.sub.2 O atmosphere with the pressure within the chamber set to atmospheric pressure. The heating temperature at this time was 300-700 example, to 500 minutes to 6 hours, and heat treatment was carried out, for example, for 3 hours.
Then, NH.sub.3 was introduced into the chamber and a heat treatment was carried out while irradiating with ultra violet light in an essentially 100% NH.sub.3 atmosphere with the pressure within the chamber set to atmospheric pressure. The heating temperature at this time was set to 500 treatment time of 3 hours.
The heat treatment of this present invention was carried out in the way described above. It was confirmed by means of secondary ion mass spectroscopy (SIMS) that a similar amount of nitrogen was included in the silicon oxide film as that obtained on carrying out a heat treatment at 900
EXAMPLE 16 This illustrative example is an example in which silicon oxide films which had been formed on a silicon film by means of the low pressure CVD method using monosilane (SiH.sub.4) and oxygen gas (O.sub.2) as raw materials are heat treated using the heat treatment apparatus shown in FIG. 5. The film-forming conditions for the silicon oxide films used in this illustrative example were substrate temperature 300-500 pressure inside the chamber of 0.1-10 torr, for example the conditions were set to 400
The way in which the temperature changed with the passage of time during the heat treatment is shown in FIG. 6(C). The substrate was heated at a rate of 5-30 during the warming period. At this time N.sub.2 was being introduced from the gas supply system 605 and the heating was carried out in an N.sub.2 atmosphere.
Subsequently, when the temperature at which the heat treatment was to be carried out was reached, ultraviolet light (center wavelength 246 nm, 185 nm) was irradiated from the ultraviolet light source 604 which was established over the conveyor 601. The heating temperature was 500-600 550 gas supply system 605 immediately before the temperature at which the heat treatment was to be carried out had been reached, and when the temperature at which the heat treatment was to be carried out was reached the heat treatment was carried out completely in a N.sub.2 H.sub.4 atmosphere. The heat treatment time was from 30 minutes to 6 hours, and it was set, for example, to 2 hours.
Subsequently, the N.sub.2 H.sub.4 was displaced with N.sub.2, and then the N.sub.2 was displaced again with N.sub.2 O, and a second heat treatment was carried out. The heat treatment time was set to 2 hours.
By heat treating silicon oxide films which have been formed by means of a PVD method or CVD method at a low temperature of 300-700 preferably of some 500-600 light, in an N.sub.2 O atmosphere as in the present invention, it is possible to reduce the carbon and hydrogen concentrations in the silicon oxide film and to increase the nitrogen concentration at the boundary between the silicon oxide and the silicon.
It is possible to increase the nitrogen concentration in a silicon oxide film, and especially at the boundary between the silicon oxide and the silicon, by subjecting a silicon oxide film which has been formed by means of a PVD method or a CVD method to a heat treatment at a low temperature of 300-700 irradiating with ultraviolet light, in an NH.sub.3 or N.sub.2 H.sub.4 atmosphere as in this present invention.
Silicon oxide films obtained with the plasma CVD method using TEOS for the raw material, the sputter method in a 100% oxygen atmosphere using synthetic quartz for the target and the low pressure CVD method and ECR-CVD method in which monosilane (SiH.sub.4) and oxygen were used for the raw material gases have been described in the illustrative examples, but unpaired bonds and large amounts of hydrogen are also included in silicon oxide films which have been formed using other PVD methods and CVD methods, and it seems to be clear that an effect which improves the silicon oxide films and which is desirable for gate insulating films is obtained by reducing the unpaired bonds and increasing the concentration of nitrogen by the execution of this present invention.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS3798061 *Jul 13, 1970Mar 19, 1974S YamazakiMethod for forming a single-layer nitride film or a multi-layer nitrude film on a portion of the whole of the surface of a semiconductor substrate or elementUS4784975 *Oct 23, 1986Nov 15, 1988International Business Machines CorporationPost-oxidation anneal of silicon dioxideUS5198392 *Jun 21, 1991Mar 30, 1993Oki Electric Industry Co., Ltd.Method of forming a nitrided silicon dioxide (SiO.sub.x N.sub.y) filmUS5219773 *Dec 3, 1991Jun 15, 1993Massachusetts Institute Of TechnologyMethod of making reoxidized nitrided oxide MOSFETsUS5237188 *Nov 27, 1991Aug 17, 1993Kabushiki Kaisha ToshibaSemiconductor device with nitrided gate insulating filmUS5376592 *Jan 19, 1993Dec 27, 1994Sony CorporationMethod of heat-treating a semiconductor wafer to determine processing conditionsUS5393683 *May 26, 1992Feb 28, 1995Micron Technology, Inc.Method of making semiconductor devices having two-layer gate structureUS5397720 *Jan 7, 1994Mar 14, 1995The Regents Of The University Of Texas SystemMethod of making MOS transistor having improved oxynitride dielectricUS5510278 *Sep 6, 1994Apr 23, 1996Motorola Inc.Method for forming a thin film transistorUS5587330 *Oct 18, 1995Dec 24, 1996Semiconductor Energy Laboratory Co., Ltd.Method for manufacturing semiconductor deviceDE4333160A1 *Sep 29, 1993Mar 30, 1995Siemens AgProduction method for a nitrided silicon oxide layer with reduced thermal loadingJP5423378A * Title not available* Cited by examinerNon-Patent CitationsReference1F. Roozeboom et al., J.Vac.Sci. Technol. B8 (6)(1990)1249 "RTP systems: a review . . . ", Nov. 1990.2 *F. Roozeboom et al., J.Vac.Sci. Technol. B8 (6)(1990)1249 RTP systems: a review . . . , Nov. 1990.3H. Fukuda et al., IEEE Trans. Electron Dev. 39(1)(1992)127 "Thin-gate SiO2 films formed by in situ multiple RTP", Jan. 1992.4 *H. Fukuda et al., IEEE Trans. Electron Dev. 39(1)(1992)127 Thin gate SiO2 films formed by in situ multiple RTP , Jan. 1992.5J. Flicstein et al., Appl. Surf. Sci. 86 (1995)286 "Tunable UV-flash krypton lamp . . . for . . . Si-based dielectrics", Feb. 1995.6 *J. Flicstein et al., Appl. Surf. Sci. 86 (1995)286 Tunable UV flash krypton lamp . . . for . . . Si based dielectrics , Feb. 1995.7J. Mi et al., Microelectronic Eng. 22 (1993)81 " . . . SiO2 films nitrided by RTP in NH3 and N2O".8 *J. Mi et al., Microelectronic Eng. 22 (1993)81 . . . SiO2 films nitrided by RTP in NH3 and N2O .9M. Severi et al., Microelectronic Eng. 19 (1992)657 " . . .SiO2 films nitrided in N2O by RTP".10 *M. Severi et al., Microelectronic Eng. 19 (1992)657 . . .SiO2 films nitrided in N2O by RTP .11 *M. Weidner et al., Thin Solid Films 234(1993)337 . . . N20 nitrided SiO films on Si .12M. Weidner et al., Thin Solid Films 234(1993)337". . . N20 nitrided SiO films on Si".13N.C. Das et al., IEEE Electron Dev. Lett. 14(1)(1993)40 " . . . SiO2, NO and ONO MOSFET's", Jan. 1993.14 *N.C. Das et al., IEEE Electron Dev. Lett. 14(1)(1993)40 . . . SiO2, NO and ONO MOSFET s , Jan. 1993.15P. Bergonzo et al., Appli. Surf. Sci. 69(1993)393 " Direct photo-deposition of SiO2 fiolms using a xenon excimer lamp", May 1993.16 *P. Bergonzo et al., Appli. Surf. Sci. 69(1993)393 Direct photo deposition of SiO2 fiolms using a xenon excimer lamp , May 1993.17P. Bergonzo et al., Microelectronic Eng. 25(1994)345 "Photo-Deposition of oxynitride and nitride films using excimer lamps", Aug. 1994.18 *P. Bergonzo et al., Microelectronic Eng. 25(1994)345 Photo Deposition of oxynitride and nitride films using excimer lamps , Aug. 1994.19 *P. Gonzalez et al., Thin Solid Films 421(193)348 Silicon oxide . . . Xe2 excimer lamp CVD . . . :1993.20P.C. Chen et al., J.Appl. Phys. 76(9)(1994)5508 " . . . N2O plasma annealed ultrathin silicon dioxides . . . ", Nov. 1994.21 *P.C. Chen et al., J.Appl. Phys. 76(9)(1994)5508 . . . N2O plasma annealed ultrathin silicon dioxides . . . , Nov. 1994.* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS6303520 *Dec 15, 1998Oct 16, 2001Mattson Technology, Inc.Silicon oxynitride filmUS6303972 *Nov 25, 1998Oct 16, 2001Micron Technology, Inc.Device including a conductive layer protected against oxidationUS6319809Jul 12, 2000Nov 20, 2001Taiwan Semiconductor Manfacturing CompanyMethod to reduce via poison in low-k Cu dual damascene by UV-treatmentUS6417115May 26, 1998Jul 9, 2002Axeclis Technologies, Inc.Treatment of dielectric materialsUS6468854Aug 31, 2000Oct 22, 2002Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6472264Aug 31, 2000Oct 29, 2002Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6475930 *Jan 31, 2000Nov 5, 2002Motorola, Inc.UV cure process and tool for low k film formationUS6489194Aug 31, 2000Dec 3, 2002Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6495800Jan 5, 2001Dec 17, 2002Carson T. RichertContinuous-conduction wafer bump reflow systemUS6566278Aug 24, 2000May 20, 2003Applied Materials Inc.Method for densification of CVD carbon-doped silicon oxide films through UV irradiationUS6607975Aug 31, 2000Aug 19, 2003Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6614181Aug 23, 2000Sep 2, 2003Applied Materials, Inc.UV radiation source for densification of CVD carbon-doped silicon oxide filmsUS6720215Aug 31, 2000Apr 13, 2004Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6740605 *May 5, 2003May 25, 2004Advanced Micro Devices, Inc.Process for reducing hydrogen contamination in dielectric materials in memory devicesUS6808976Aug 31, 2000Oct 26, 2004Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6838734 *Dec 19, 2002Jan 4, 2005Taiwan Semiconductor Manufacturing Co., Ltd.ESD implantation in deep-submicron CMOS technology for high-voltage-tolerant applicationsUS6849300Nov 4, 2002Feb 1, 2005Hynix Semiconductor, Inc.Method for forming high dielectric layers using atomic layer depositionUS6852622Aug 31, 2000Feb 8, 2005Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6897512Oct 16, 2001May 24, 2005Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6901568 *Apr 22, 2003May 31, 2005Nec Electronics CorporationMethod for fabricating transistorUS6905920 *Aug 31, 2001Jun 14, 2005Seiko Epson CorporationMethod for fabrication of field-effect transistor to reduce defects at MOS interfaces formed at low temperatureUS6916699Aug 31, 2000Jul 12, 2005Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6919282Jan 8, 2003Jul 19, 2005Semiconductor Energy Laboratory Co., Ltd.Method of fabricating a semiconductor deviceUS6924188 *Aug 31, 2000Aug 2, 2005Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS6940124Sep 30, 2002Sep 6, 2005Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and manufacturing method thereofUS6949433 *Feb 7, 2003Sep 27, 2005Fasl LlcMethod of formation of semiconductor resistant to hot carrier injection stressUS6949481Dec 9, 2003Sep 27, 2005Fasl, LlcProcess for fabrication of spacer layer with reduced hydrogen content in semiconductor deviceUS6955965Dec 9, 2003Oct 18, 2005Fasl, LlcProcess for fabrication of nitride layer with reduced hydrogen content in ONO structure in semiconductor deviceUS6972452Mar 19, 2004Dec 6, 2005Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS7041550Aug 31, 2000May 9, 2006Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS7049191Aug 31, 2000May 23, 2006Micron Technology, Inc.Method for protecting against oxidation of a conductive layer in said deviceUS7064388Dec 28, 2004Jun 20, 2006Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and method for manufacturing the sameUS7067861Aug 31, 2000Jun 27, 2006Micron Technology, Inc.Device and method for protecting against oxidation of a conductive layer in said deviceUS7094657Aug 31, 2000Aug 22, 2006Micron Technology, Inc.Method for protecting against oxidation of a conductive layer in said deviceUS7094993Oct 19, 2004Aug 22, 2006Radiant Technology Corp.Apparatus and method for heating and cooling an articleUS7098149Mar 4, 2003Aug 29, 2006Air Products And Chemicals, Inc.Mechanical enhancement of dense and porous organosilicate materials by UV exposureUS7115488Aug 17, 2004Oct 3, 2006Semiconductor Energy Laboratory Co., Ltd.Method of manufacturing semiconductor deviceUS7129185 *Oct 19, 2004Oct 31, 2006Tokyo Electron LimitedSubstrate processing method and a computer readable storage medium storing a program for controlling sameUS7166899Jul 15, 2005Jan 23, 2007Semiconductor Energy Laboratory Co., Ltd.Semiconductor device, and method of fabricating the sameUS7170036Dec 16, 2002Jan 30, 2007Radiant Technology CorporationApparatus and method for heating and cooling an articleUS7329906Dec 22, 2004Feb 12, 2008Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and method for forming the sameUS7372114Oct 10, 2006May 13, 2008Semiconductor Energy Laboratory Co., Ltd.Semiconductor device, and method of fabricating the sameUS7456474Apr 29, 2005Nov 25, 2008Semiconductor Energy Laboratory Co., Ltd.Semiconductor device having insulating filmUS7468290Jul 21, 2003Dec 23, 2008Air Products And Chemicals, Inc.Mechanical enhancement of dense and porous organosilicate materials by UV exposureUS7504343May 5, 2006Mar 17, 2009Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and method for manufacturing the sameUS7537979Aug 24, 2006May 26, 2009Semiconductor Energy Laboratory Co., Ltd.Method of manufacturing semiconductor deviceUS7821071Mar 6, 2009Oct 26, 2010Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and method for manufacturing the sameUS7855416Nov 24, 2008Dec 21, 2010Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and manufacturing method thereofUS7932188Oct 31, 2008Apr 26, 2011Air Products And Chemicals, Inc.Mechanical enhancement of dense and porous organosilicate materials by UV exposureUS8154059Oct 22, 2010Apr 10, 2012Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and method for manufacturing the sameUS8563095Mar 15, 2010Oct 22, 2013Applied Materials, Inc.Silicon nitride passivation layer for covering high aspect ratio featuresUS8610182Apr 5, 2012Dec 17, 2013Semiconductor Energy Laboratory Co., Ltd.Semiconductor device and method for manufacturing the sameCN100539010CJun 18, 2007Sep 9, 2009中芯国际集成电路制造(上海)有限公司System and method for processing wafer surface material layerCN101088150BNov 10, 2005Feb 13, 2013应用材料公司Tensile and compressive stressed materials for semiconductorsEP1122333A2 *Jan 31, 2001Aug 8, 2001Motorola, Inc.UV cure process and tool for low k film formationEP1457583A2Mar 2, 2004Sep 15, 2004Air Products And Chemicals, Inc.Mechanical enhancement of dense and porous organosilicate materials by UV exposureWO2000042724A1 *Sep 30, 1999Jul 20, 2000Keiji FukuzawaInformation distribution systemWO2006055459A2 *Nov 10, 2005May 26, 2006Applied Materials IncTensile and compressive stressed materials for semiconductors* Cited by examinerClassifications U.S. Classification438/795, 257/E21.413, 257/E21.192, 438/162, 438/910, 438/909International ClassificationH01L21/28, C23C14/58, C23C16/56, H01L21/336, H01L21/316Cooperative ClassificationY10S438/909, Y10S438/958, Y10S438/91, C23C14/58, C23C16/56, H01L29/66757, H01L21/28158European ClassificationH01L21/28E2C, C23C16/56, C23C14/58Legal EventsDateCodeEventDescriptionMar 24, 2011FPAYFee paymentYear of fee payment: 12Mar 23, 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