JP4476984B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device that provides a clean semiconductor interface by removing the contamination in a semiconductor device manufacturing process that cannot avoid carbon contamination such as a process in a clean room using a hepper filter. Is.
In particular, in thin film transistor (TFT) manufacturing methods using thin film semiconductors such as in the liquid crystal display field, removal of contaminants by carbon at the interface between the active layer and the gate insulating film, and gate insulation formed using an organosilane source The present invention relates to removal of carbon impurities in a film, and relates to a method for manufacturing a thin film semiconductor device that provides a clean semiconductor interface and a low carbon concentration gate insulating film.

  In the manufacturing method of a semiconductor device, removal of contaminants on the surface and prevention of contamination have been established as various methods as an old problem. For removing heavy metals, a method of removing the heavy metal by adding hydrogen peroxide to hydrochloric acid is quite widely known. For removal of physical adsorbates, cleaning using ultrasonic cavitation or cleaning with a brush is often used.

Also, in the field of liquid crystal displays in which a large number of thin film transistors are formed on an insulating substrate, the use of orthotetraethyl silicate chemical formula Si (OC ₂ H ₅ ) ₄ (so-called TEOS) as a source gas can improve the step coverage. By utilizing this, so-called disconnection of the thin film transistor wiring is reduced.

  Further, in the field of liquid crystal display using a process of 600 ° C. or lower rather than a high temperature such as a silicon wafer, it is used as a gate oxide film and a base film in addition to the interlayer insulating film. In thin film transistors (also called TFTs) that are applied to liquid crystal displays, etc., tetraethyl orthosilicate is used as the source gas for the base film, gate insulating film, and interlayer insulating film formed on an insulating substrate such as a glass substrate. The film is formed by a thermal CVD method, a plasma CVD method, or the like. However, there is a large amount of carbon remaining, and there remains a problem in the characteristics as an oxide film.

  For organic substances such as carbon adhering to the surface, cleaning with a solution obtained by adding sulfuric acid to hydrogen peroxide water, dry ashing using ozone or oxygen plasma, and the like are well known. However, the inventors' research has shown that there are more complex situations regarding carbon removal. Speaking of where the contamination of carbon comes from, the photoresist used to form an arbitrary pattern during the photolithography process is a photosensitive organic substance, which also causes carbon contamination.

  In addition, in the manufacture of semiconductor devices, the thin film process is no longer an essential requirement, and a vacuum device for that is also an essential device, but oil is still used for the vacuum pump for evacuating the vacuum device. Some of them also cause carbon pollution. In addition, Teflon (registered trademark) (PFA), polypropylene (PP), polyvinylidene fluoride (PVDF), trifluoroethylene covalent resin (ECTFE), and tetrafluoroethylene covalent resin (ETFE) used as a substrate carrier. ), Vapor pressure from polyethylene (PE), etc., and contamination from floor materials and wall material filters in clean rooms.

  Dry ashing is performed after the photolithographic process, and immediately before each process, organic substances are removed by using a solution obtained by adding hydrochloric acid to hydrogen peroxide in a 1: 1 ratio by heating to 80 ° C. (hereinafter referred to as wet ashing). Called). The conventional method is to immediately perform the next processing. It seemed that most organic substances could be removed by dry ashing and wet ashing. However, when carbon contamination on the substrate surface was evaluated by known XPS measurement, only the C—C bond (carbon single bond) was obtained. It was found that it was hardly removed.

  FIG. 2 shows a substrate surface 21 (dotted line graph in FIG. 2) after photoresist coating, pre-baking, exposure, development, post-baking and resist peeling, and the substrate after dry ashing and wet ashing of the substrate. The surface 22 (solid line graph in FIG. 2) was measured using XPS. As measurement conditions, in order to obtain surface information as much as possible, the angle of the detector was set to 15 °, and an area of 1 mmφ on the substrate surface was measured. The horizontal axis represents the binding energy, the unit is eV, the vertical axis is the intensity of the detector, and the unit is an arbitrary unit.

  From the graph of FIG. 2, it can be seen that the peak near 284.8 eV increases before and after (solid line) dry ashing and wet ashing, and all other peaks decrease. The peak at 284.8 eV indicates the presence of a C—C single bond.

  This shows that removing carbon single bonds is very difficult and almost impossible with conventional dry ashing and wet ashing. Since this carbon remains as an impurity on the substrate surface, for example, when an oxide film or the like is formed thereon, carbon remains at the interface with the oxide film, becomes a recombination center at the interface, and causes charge trapping, The electrical characteristics of the semiconductor, such as the mobility of the thin film transistor, are deteriorated, and the bonding state is not stable, so that the interface state is temporally changed and the reliability is lowered by the continuous application of an electric field.

  In addition, Japanese Patent Application Laid-Open No. 4-177735 by the present applicant describes that plasma hydrogen cleaning of a semiconductor surface is performed by applying a bias to a substrate using 100% hydrogen before forming a film by a sputtering apparatus. ing. However, at the time of filing this invention, it was not known that hydrogen radicals had an effect on the carbon single bond, so that a bias was applied to the substrate and the sputtering effect of the hydrogen ions was used to apply the effect on the surface of the semiconductor. I was cleaning.

  Therefore, in order to improve the interface characteristics, it is necessary to balance the effect of removing impurities and damage caused by sputtering, so that the process margin cannot be increased. Therefore, processes that can use this plasma hydrogen cleaning have been limited.

  Further, not only carbon contamination on the surface but also carbon contamination during film formation using an organic silane source is a serious problem. As a film-forming method using tetraethyl orthosilicate, which has been widely used in the past, as a plasma CVD method, a substrate to be formed is placed in a evacuable chamber having parallel plate electrodes. To do.

  At this time, one side of the parallel plate electrode is connected to a high frequency power source and connected to a so-called cathode. The other electrode is connected to the ground, and the substrate is disposed on the ground side electrode, the so-called anode side. The tetraethyl silicate is heated for liquid at room temperature to increase the vapor pressure and introduced into the chamber, or the carrier gas is bubbled into the tank and introduced into the chamber together with the carrier gas. The tetraethyl orthosilicate decomposed in the plasma is characterized by forming a precursor and fluidly moving on the substrate, thereby forming a film with good step coverage.

Precursors moving on the substrate collide with each other, and oxygen ions, oxygen radicals, and ozone formed in the plasma collide with each other to cause a drawing reaction on the surface, thereby forming SiO _x . When a large amount of oxygen is introduced, the drawing reaction from the precursor formed from tetraethyl orthosilicate on the surface is promoted, and the amount of carbon is reduced, but conversely, a film having poor step coverage is obtained.

If the amount of oxygen introduced is small, the step coverage is improved, but many bonds of carbon, oxygen, and hydrogen remain, resulting in a highly hygroscopic film. When measurement is performed by infrared absorption, a film in which absorption near 3660 cm ⁻² increases with time. Absorption in the vicinity of 3660 cm ⁻² is mainly due to Si—OH bonds, which indicates that the formed film is hygroscopic.

As another film forming method using normal tetraethyl silicate, there is an atmospheric pressure CVD method using ozone and heat. In this method, a tetraethyl silicate tank is bubbled with N ₂ on a substrate heated to 300 to 400 ° C. and introduced into the reaction chamber. Oxygen is generated through an ozonizer and introduced into the chamber. is there. In this method, since the step coverage is high and the film forming speed is high, it is also used for an interlayer insulating film or the like that requires multilayer wiring such as a memory such as an LSI or DRAM. Thereafter, so-called flattening is performed by using etch back, SOG (SPIN ON GLASS), CMP (CHEMICAL MECHANICAL POLISHING), or the like.

  Among the contaminants of carbon on the substrate surface in the thin film semiconductor device manufacturing process, especially at various semiconductor formation interfaces by reducing impurities due to carbon single bonds (C-C) that can hardly be removed by conventional wet ashing and dry ashing. Deterioration of electrical characteristics due to impurities caused by carbon, reduction of reliability, etc. are reduced. In particular, carbon contamination at the interface between the active layer semiconductor and the gate insulating film is reduced.

  In addition, when forming a film using an organic gas such as tetraethyl silicate as the source, improving the step coverage increases the hygroscopicity and carbon content, resulting in lack of reliability and poor semiconductor properties. Was imitating. Also, in order to reduce the carbon content, adding a large amount of oxygen to an organosilane gas such as regular tetraethyl silicate deteriorates the step coverage and causes wiring breakage, resulting in lack of reliability, semiconductors The imperfection of the characteristic was imitated.

  By using the present invention, it is possible to eliminate the above-described problems, to provide good step coverage, to reduce the carbon content, to reduce moisture absorption, and to increase the deposition rate. By using the present invention, carbon impurities in a semiconductor interface can be reduced and carbon in a gate insulating film formed using an organosilane source can be reduced without losing its step coverage. it can.

  The present inventor has found that active hydrogen such as hydrogen radicals or hydrogen ions acts effectively on removing impurities due to C—C single bonds attached to the substrate surface. This was discovered in research for expanding the cleaning process margin using the above-described sputtering effect of hydrogen. The interface is hardly damaged by sputtering, and active hydrogen works effectively to remove carbon impurities, so that a good interface can be produced.

In addition, since cleaning by sputtering involves spatter damage, the process margin cannot be increased because it is necessary to balance the effect of removing impurities and damage. However, since active hydrogen is used, there is no sputter damage. Since impurities can be removed, the process margin can be increased. It was also found that hydrogen radicals alone have a sufficient effect, but the removal effect increases when oxygen radicals or active oxygen such as ozone or oxygen ions are added thereto. This is because hydrogen and oxygen radicals react with carbon bonds to form gases such as CH _X , CO _X , and COH, and as a result, carbon is gasified.

  In order to generate hydrogen radicals or hydrogen ions, for example, a substrate is placed in a parallel plate electrode type plasma apparatus. At this time, it is better to place the substrate on the anode (anode) side so as not to be damaged by plasma ions, etc. If the substrate can be heated, the effect of the separation will be enhanced by heat. The

  When heat is applied, the substrate temperature can be set to 900 ° C. or higher if the substrate has a relatively high heat resistance such as quartz or Si wafer. It is effective to use one of these. In addition, when a metal having a low melting point such as Al already exists on a Si wafer or a quartz substrate or when a glass substrate is used, the substrate temperature cannot be so high. It is more convenient to use metal.

  When hydrogen gas is introduced and high frequency power is applied between the parallel plate electrodes, plasma is generated. In the plasma, highly active neutral hydrogen radicals are generated together with hydrogen ions and electrons. In order to increase the amount of active substances such as radicals or ions, it is useful to increase the high-frequency power, but using microwaves utilizing electron cyclotron resonance can further increase the amount of hydrogen radicals and ions. Is possible. The generated hydrogen radicals and ions reach the substrate surface, where they react with the carbon single bond CC to remove it. The reacted and gasified carbon is exhausted by a pump.

Further, when heated hydrogen is brought into contact with a catalyst such as Pd / Al ₂ O ₃ , Pd / C, or Ru / C, hydrogen radicals are generated due to the catalytic action, so that the hydrogen radicals are generated without causing plasma damage. It can be carried to the substrate surface where carbon single bonds can be removed.

In order to effectively remove C═C, C—O, C═O, etc. other than the carbon single bond, it is very effective to use oxygen radicals, ozone, or oxygen ions. When oxygen radicals or the like come into contact with carbon bonds, it is possible to gasify in the form of CO _x and perform so-called ashing treatment.

  In order to generate oxygen radicals or active oxygen such as ozone or oxygen ions, a substrate is placed, for example, in a parallel plate electrode type plasma apparatus. At this time, it is better to place the substrate on the anode (anode) side so as not to be damaged by the ions in the plasma. If the substrate can be heated, the heat will be released and the effect will be Be improved.

  When oxygen gas is introduced and high frequency power is applied between the parallel plate electrodes, plasma is generated. In the plasma, highly active neutral oxygen radicals and ozone are generated together with oxygen ions and electrons. In order to increase the amount of radicals and the like, it is useful to increase the high-frequency power, but it is possible to further increase the amount of oxygen radicals and the like by using a microwave utilizing electron cyclotron resonance. The generated oxygen radicals reach the substrate surface, where they react with carbon bonds and remove them. The reacted and gasified carbon is exhausted by a pump.

  Further, when oxygen gas is irradiated with ultraviolet rays, a large amount of ozone is generated, so that hydrogen radicals can be carried to the substrate surface without causing plasma damage, and carbon heavy bonds can be removed there.

  It is very effective to use both when removing carbon on the substrate surface with active hydrogen and active oxygen. First, it is possible to remove carbon impurities mainly composed of carbon bonds other than carbon single bonds using active oxygen, and then remove carbon impurities mainly composed of carbon single bonds with active hydrogen. It is also possible to remove active hydrogen and active oxygen at the same time.

  In order to mix active hydrogen and active oxygen, hydrogen gas and oxygen gas are simultaneously introduced into a parallel plate type plasma apparatus capable of generating plasma or a microwave plasma apparatus using an electron cyclotron, and the plasma is generated there. When generated, hydrogen ions, hydrogen radicals, oxygen ions, oxygen radicals, and ozone are simultaneously generated to remove carbon on the substrate surface, and the removed carbon is exhausted by a vacuum pump.

In particular, when there is a catalyst such as heated Pd / Al ₂ O ₃ , Pd / C, or Ru / C, and hydrogen and oxygen are introduced into a treatment chamber that is irradiated with ultraviolet rays, the hydrogen reacts with hydrogen radicals by a catalytic reaction. Oxygen is generated and ozone is generated by ultraviolet rays, and carbon impurities on the substrate surface can be removed without causing plasma damage to the substrate.

In addition to generating active hydrogen and active oxygen using hydrogen and oxygen, H ₂ O can also be used. H ₂ O is introduced into a parallel plate type plasma apparatus capable of generating plasma or a microwave plasma apparatus using an electron cyclotron.

There are several ways to introduce H ₂ O. A tank containing H ₂ O is bubbled using an inert gas such as He, Ne, or Ar as a carrier gas, thereby carrying H ₂ O as a gas to the processing chamber. There is also a method in which the entire tank from the tank containing H ₂ O to the processing chamber is heated, the vapor pressure of H ₂ O is increased, and the processing chamber is bulged as it is.

The introduced H ₂ O is decomposed by the plasma and simultaneously generates hydrogen ions, hydrogen radicals, oxygen ions, oxygen radicals, and ozone. Thereby, carbon impurities on the substrate surface can be removed. The removed carbon is exhausted by a vacuum pump.

FIG. 1 is a graph showing the degree of carbon impurity removal by XPS on the substrate surface obtained according to the present invention.
Photoresist coating, pre-baking, exposure, development, post-baking, resist stripping, and then substrate surface 11 after standing in a clean room for one day (broken line graph in FIG. 1), and dry ashing and wet ashing of the substrate After the substrate surface 12 (one-dotted line graph in FIG. 1) has been performed, the present invention is used after photoresist coating, pre-baking, exposure, development, post-baking, resist stripping, and leaving in a clean room for one day. The substrate surface 13 (solid line graph in FIG. 1) after removing carbon impurities was measured using XPS. As measurement conditions, in order to obtain surface information as much as possible, the angle of the detector was set to 15 °, and an area of 1 mmφ on the substrate surface was measured. The horizontal axis represents the binding energy, the unit is eV, the vertical axis is the intensity of the detector, and the unit is an arbitrary unit.

  From the graph of FIG. 1, it can be seen that the peaks near 284.8 eV increase before and after dry ashing and wet ashing 12, and all other peaks decrease. Moreover, it can be seen that the peak near 284.8 eV is greatly reduced in the graph 13 using the present invention.

  The reason why the peak does not become completely zero even when the present invention is used is that the measurement is not in-situ measurement, and after removing the carbon impurity using the present invention, there is a gap between the adhering carbon impurities. It appears to be. However, a significant effect is seen compared to the case where the present invention is not used. By using the present invention, carbon contaminants having a carbon single bond can be reduced.

In addition, when an oxide film is formed by plasma CVD using regular tetraethyl silicate, as a method of reducing carbon during film formation, oxygen and tetraethyl silicate were mixed to form a film. It has been found that the use of active hydrogen such as hydrogen radicals and hydrogen ions during film formation is effective. Active hydrogens such as hydrogen radicals and hydrogen ions react with carbon to form CH _X and gasify the carbon. In particular, carbon in the film formation can be removed by cutting the C—C bond, which is a single bond of carbon, and gasifying it as CH ₄ or C—OH.

  Compared with oxygen, hydrogen has a so-called decarbonizing effect on carbon, and since the atoms are small, the sputtering effect of hydrogen ions on the film and the substrate is almost negligible when compared with oxygen. . Therefore, when film formation is performed by plasma CVD with a mixture of normal tetraethyl silicate, oxygen, and hydrogen, the mixing ratio of normal tetraethyl silicate and oxygen is such that the step coverage is good and the productivity is good. And a system in which hydrogen is mixed for decarbonization. The effect is particularly great when an amount of 0.01 to 0.5 times the amount of regular tetraethyl silicate is introduced.

  As a result, precursors from tetraethyl orthosilicate generated by plasma and oxygen ions, ozone, and oxygen radicals repeat surface reactions related to film formation on the substrate surface, while the precursors change into various types of precursors. An oxide film with good step coverage is formed by flowing on the substrate surface. Thus, as the oxide film is formed by the reaction of the precursor and oxygen ions, ozone, or oxygen radicals, hydrogen ions or hydrogen radicals react with carbon atoms on the substrate surface to gasify the carbon. The gasified carbon is exhausted by a vacuum pump.

  When the present invention is used for film formation using atmospheric pressure CVD, a catalytic method is used to convert part of hydrogen into hydrogen radicals. Catalysts include 3d-transition metals such as platinum, palladium, reduced nickel, cobalt, titanium, panadium, and tantalum, or aluminum, nickel, platinum / silicon, platinum / chlorine, platinum / rhenium, nickel / molybdenum, cobalt / molybdenum, etc. Or a mixture or compound of the above transition metals and alumina, silica gel, or the like, or Raney cobalt, ruthenium, palladium, nickel, or the like or a mixture or compound of these with carbon is suitable. Use in state.

  However, substances that have a low melting point and significantly increase the initial adsorption rate of the reactive substance, and substances containing an alkali metal such as sodium that are easily vaporized in the substance, such as copper and tungsten, are not preferable. According to the experiment, the catalyst was significantly deteriorated above the decomposition temperature of the reactive substance. The amount and density of the catalyst are related to the effective contact area with the reactive gas, and may be adjusted as necessary. Active hydrogen radicals are generated by passing hydrogen through a heated catalyst. Oxygen generates active ozone by passing through an ozonizer.

  Regarding the generation of hydrogen radicals, in the plasma CVD method, hydrogen radicals are generated by plasma, and in the atmospheric pressure CVD method, they are generated by the catalytic method, but this can be reversed. An active hydrogen radical can be generated in advance by a catalytic method and introduced into a plasma CVD apparatus. An active hydrogen radical can be formed in advance by discharge, and then the gas nozzle of an atmospheric pressure CVD apparatus can be used. It is also possible to mix.

In addition, when an oxide film is formed using regular tetraethyl silicate, oxygen is used as a source because active oxygen such as oxygen radicals, oxygen ions, and ozone is used. However, in the present invention, it is also possible to use H ₂ O in order to use an active hydrogen radical or hydrogen ion. However, since H ₂ O and tetraethyl orthosilicate are highly reactive, if they are mixed in the piping before reacting on the substrate, the piping may be clogged. In plasma CVD, it is preferable to separate the tetraethyl silicate introduction pipe and the H ₂ O introduction pipe.

Instead of orthosilicate ethyl, by using an organosilane containing F such _{FSi (OC 2 H 5) 4} , low content of carbon, yet the SiO _X of low F-doped dielectric constant than SiO _X Since it can be manufactured, it is possible to reduce the lateral capacitance between wirings due to the interlayer insulating film. Further, the present invention is very effective for improving the decarbonization and step coverage and securing the film forming speed when using an organic silane system containing carbon as a source.

  In the present invention, particularly in a top gate type thin film transistor (TFT), after forming a semiconductor layer as an active layer, the active layer is patterned, and then a gate insulating film is formed. For this reason, the contamination of carbon on the surface of the active layer is severe, and forming a gate insulating film without removing it causes poor reliability as well as poor transistor characteristics. In addition, when fabricating an oxide film using an organosilane source on the gate insulating film, it is very important to obtain an oxide film with good step coverage and reduced carbon and a low moisture absorption. It is.

  As described above, the present invention relates to the removal of carbon contaminants in a semiconductor device manufacturing method, and removes contamination of the substrate surface due to all carbon contamination including carbon single bonds without being affected by sputter damage. By doing so, there is a great effect in improving the characteristics and reliability of a semiconductor device having a MOS type or MIS type structure in which the semiconductor interface is particularly important.

  In particular, carbon impurities in an oxide film using an organosilane source can also be removed, and a gate insulating film of a thin film semiconductor device can be improved, which has a great effect on improvement in characteristics and reliability.

(Function)
By using the present invention, carbon impurities that could not be removed by conventional dry ashing or wet ashing can be significantly reduced in the manufacture of semiconductor devices, and in an oxide film using an organosilane source during film formation. Carbon impurities can be greatly reduced. In particular, it is effective in removing impurities and contaminants containing a carbon single bond represented by C—C, so that the interface at the time of stacking of semiconductors is cleaned, and oxidation using an organosilane source is performed. The effects of improving the electrical characteristics and reliability of thin film semiconductor devices by reducing carbon impurities in the film are immeasurable.

FIG. 3 shows a cross section of a process for forming a transistor in the embodiment.
In this embodiment, the present invention is used when a thin film transistor is formed on a glass substrate.

On the glass substrate 31, 2000 nm of SiO ₂ was formed as a base film 32 by using an atmospheric pressure CVD method. Thereafter, 500 nm of amorphous Si is formed as an active layer by plasma CVD, and a mask is formed by patterning a resist using a known photolithography method, and dry etching of amorphous Si using CF ₄ + O ₂ is performed. After that, the resist was stripped using an alkaline stripping solution to form islands 33. Thereafter, the island 33 was changed from amorphous Si to polysilicon by solid phase growth at 600 ° C. for 24 hours. This is FIG.

  After the resist is stripped with a stripping solution, at least part of the surface of the island 33 is contaminated with carbon containing carbon single bonds. The present invention is used to remove it. Since the gate insulating film 34 is formed on the island 33, the surface of the island 33 becomes a region for forming the most important channel in TFT characteristics. Therefore, it is important to remove carbon contaminants on the surface of the island 33. The following method was tried as a removal method.

  As method 1, as a method of performing plasma processing, a substrate 31 on which an island 33 is formed is disposed on the anode side of a parallel plate type plasma processing apparatus. The electrode interval between the anode and the cathode, which are parallel plate electrodes, was adjusted between 30 and 150 mm. Typically, it was performed at 70 mm, but there are few problems if conditions are selected whether it is larger or smaller.

  As for the gas, a cathode electrode serves as a shower head, from which gas is introduced into the reaction space, and a device such as a diffusion plate is provided in the shower head so that the gas flows uniformly on the surface of the substrate 31. The same amount of hydrogen gas and oxygen gas was introduced. Quantitatively, although depending on the size of the processing chamber, the pressure for performing the plasma processing was between 50 mTorr and 10 Torr, and the residence time of the gas was 5 seconds or less. If the residence time exceeds 10 seconds, re-deposition of gasified carbon may occasionally occur, so as much as possible, the removed carbon was reduced to 5 seconds or less in order to quickly exhaust the carbon. If it is less than a second, there is no problem. For example, if a gas of 316 SCCM is flowed at a pressure of 1 Torr in a 40 liter chamber, the residence time will be about 10 seconds.

  The residence time is the product of the chamber volume and the pressure in the chamber divided by the gas flow rate. To reduce the residence time, the chamber volume and pressure can be reduced or the gas flow rate can be increased. It becomes necessary. In this example, the residence time was about 4 seconds with a chamber volume of 40 liters, a processing pressure of 1 Torr, oxygen of 400 SCCM, and hydrogen of 400 SCCM.

The plasma generating means was high frequency discharge. As a high frequency, 10 to 100 MHz was used, but in the example, 20 MHz was used. As the applied power, 0.1 to ² W / cm ² was input. If the power is less than 0.1 W / cm ² , removal is possible but it takes too much processing time. On the other hand, if it exceeds ² W / cm ² , the electrode is heated, so that it is necessary to cool the electrode, which leads to an increase in size and cost of the apparatus. In this example, 0.8 W / cm ² was charged.

  When the substrate is heated, the removal capability increases. Typically, when the substrate temperature is about 200 to 500 ° C., the removal capability increases. However, since there is a sufficient effect even at room temperature to 200 ° C., this embodiment is performed at room temperature. The plasma processing time is about 1 to 10 minutes. This varies greatly depending on various conditions (gas residence time, high frequency, input power, substrate temperature), but taking too much time is not preferable as a manufacturing process. In this example, it was performed for 2 minutes.

In addition to generating hydrogen radicals and oxygen radicals using hydrogen and oxygen, H ₂ O can also be used. There are several ways to introduce H ₂ O. A tank containing H ₂ O is bubbled using an inert gas such as He, Ne, or Ar as a carrier gas, thereby carrying H ₂ O as a gas to the processing chamber. There is also a method in which the entire tank from the tank containing H ₂ O to the processing chamber is heated, the vapor pressure of H ₂ O is increased, and the processing chamber is bulged as it is.

The introduced H ₂ O is decomposed by the plasma and simultaneously generates hydrogen ions, hydrogen radicals, oxygen ions, oxygen radicals, and ozone. In the experiments by the inventors, the same effect was observed even when bubbling a tank containing H ₂ O at 500 to 1000 SCCM of He as a carrier gas.

  As a method 2, the substrate 31 on which the island 33 is formed is arranged in a microwave plasma processing apparatus using electron cyclotron resonance as a method for performing plasma processing. High-density plasma is generated at the resonance point by microwave 2.45 GHz and magnetic field 875 Gauss. The substrate 31 is arranged so that ions, electrons, and radicals are carried from the resonance point to the substrate 31 by a diffusion magnetic field. As the gas, hydrogen and oxygen were introduced from a position away from the substrate 31 at the electron cyclotron resonance point.

The same amount of hydrogen gas and oxygen gas was introduced. Quantitatively, although depending on the size of the processing chamber, the pressure for performing the plasma processing is between 1 × 10 ^{−5 and} 1 × 10 ⁻³ Torr, which is almost the pressure in the molecular flow region. It is not necessary to consider so much. The removed carbon is quickly exhausted because the pressure is low in the molecular flow region.

In order to perform the plasma treatment at a low pressure, the gas and the removed product may be exhausted using a turbo molecular pump, a composite turbo molecular pump, a diffusion pump, or the like. As the gas flow rate, it is necessary to determine the gas flow rate so that the pressure is 1 × 10 ⁻⁵ to 1 × 10 ⁻³ Torr at which plasma is generated by electron cyclotron resonance rather than the flow rate itself. In this embodiment, oxygen is 50 SCCM and hydrogen is 150 SCCM. The applied power was 1.0 to 3 KW. In this example, 1.5 kW was used.

  When the substrate is heated, the removal capability increases. Typically, when the substrate temperature is about 200 to 500 ° C., the removal capability increases. However, there are sufficient effects even at room temperature to 200 ° C. In this embodiment, the substrate temperature is 250 ° C.

The plasma processing time is about 1 to 10 minutes. This greatly varies depending on various conditions (gas flow rate, input power, substrate temperature), but taking too much time is not preferable as a manufacturing process. In this example, it was performed for 1 minute.
In addition to generating hydrogen radicals and oxygen radicals using hydrogen and oxygen, H ₂ O can also be used. There are several ways to introduce H ₂ O. A tank containing H ₂ O is bubbled using an inert gas such as He, Ne, or Ar as a carrier gas, thereby carrying H ₂ O as a gas to the processing chamber. There is also a method in which the entire tank from the tank containing H ₂ O to the processing chamber is heated, the vapor pressure of H ₂ O is increased, and the processing chamber is bulged as it is. The introduced H ₂ O is decomposed by the plasma and simultaneously generates hydrogen ions, hydrogen radicals, oxygen ions, oxygen radicals, and ozone. In the experiments by the inventors, the same effect can be obtained by heating the tank containing H ₂ O to 80 ° C. and heating all of the tank to the processing chamber at 120 ° C. and introducing ₂₀ to 100 SCCM of H ₂ O. Was seen.

  As a method 3, as a method of performing the treatment by the catalytic method, the substrate 31 on which the island 33 is formed is disposed on the heating zone side of the heat treatment apparatus of the horizontal heating furnace. The catalyst is also located in the heating zone.

  Catalysts include platinum, palladium, reduced nickel, cobalt, titanium, panadium, tantalum and other 3d transition metals or aluminum, nickel, platinum / silicon, platinum / chlorine, platinum / rhenium, nickel / molybdenum, cobalt / molybdenum, etc. Or a mixture or compound of the above transition metals and alumina, silica gel or the like, or Raney cobalt, ruthenium, palladium, nickel, or the like or a mixture or compound of these with carbon is suitable. Use in the form of powder or powder.

  However, substances that have a low melting point and significantly increase the initial adsorption rate of the reactive substance, and substances containing an alkali metal such as sodium that are easily vaporized in the substance, such as copper and tungsten, are not preferable. According to the experiment, the catalyst was significantly deteriorated above the decomposition temperature of the reactive substance.

  The amount and density of the catalyst are related to the effective contact area with the reactive gas, and may be adjusted as necessary. In this example, 10% by weight of palladium mixed with alumina was used as a catalyst with a large surface area. In addition, an ultraviolet irradiation device for generating ozone is provided in front of the heating zone. The gas can be used at a reduced pressure of about normal pressure to about 500 Torr.

  When hydrogen and oxygen are introduced, first, ozone is generated from the oxygen by ultraviolet irradiation, and hydrogen that touches the catalyst becomes active hydrogen radicals, and the ozone and hydrogen radicals reach the substrate 31. The appropriate distance between the ultraviolet irradiation and the catalyst and the substrate 31 is about 50 mm to 1 m. This distance can be made to flow uniformly on the surface of the substrate 31, and the life of hydrogen radicals and ozone is sufficiently long.

  By heating the heating zone to 300 to 700 ° C., hydrogen radicals can be formed by catalytic reaction. When the temperature was set to 700 ° C. or higher, the catalyst was significantly deteriorated. However, since the temperature varies depending on the catalyst used, it is necessary to adjust the temperature depending on the catalyst used. In this embodiment, hydrogen 150SCCM and oxygen 250SCCM were used, and the temperature of the heating zone was set to 500 ° C. The time may be about 1 to 30 minutes. In this example, the time was 10 minutes.

In addition to generating hydrogen radicals and oxygen radicals using hydrogen and oxygen, H ₂ O can also be used. There are several ways to introduce H ₂ O. A tank containing H ₂ O is bubbled using an inert gas such as He, Ne, or Ar as a carrier gas, thereby carrying H ₂ O as a gas to the processing chamber. There is also a method in which the entire tank from the tank containing H ₂ O to the processing chamber is heated, the vapor pressure of H ₂ O is increased, and the processing chamber is bulged as it is. The introduced H ₂ O is decomposed by the plasma and simultaneously generates hydrogen ions, hydrogen radicals, oxygen ions, oxygen radicals, and ozone. In the experiments conducted by the inventors, the same effect was observed even when bubbling a tank containing H ₂ O with N ₂ 50 SCCM as the carrier gas.

  For comparison as Method 4, a substrate 31 having islands 33 after peeling with a peeling solution is washed with a known sulfuric acid: hydrogen peroxide solution 1: 1 heated to 80 ° C. for 10 minutes, and then a known plasma. A product subjected to dry ashing was also produced.

  Next, a silicon oxide film as the gate insulating film 34 was formed on the island 33 by using a known plasma CVD method. An in-line type multi-chamber, a cluster type multi-chamber, or a single chamber or a load-lock chamber in which carbon removal is performed in the same room as the apparatus for forming the silicon oxide film and the apparatus of the present invention can be continuously formed without breaking the vacuum. Since a gate insulating film can be formed immediately after removing carbon, a cleaner interface can be obtained. In this embodiment, TEOS which is an organic silane and oxygen are mixed and a silicon oxide film having a thickness of 500 mm is formed by using a plasma CVD method. This becomes FIG. 3 (B).

After forming the gate insulating film 34, after laminating Al, doped polysilicon, Cr, Ta, etc. as a conductive film, the resist is patterned by a photolithography process, and the conductive film is etched into a desired shape. Thus, the gate electrode 37 is manufactured. In this embodiment, Al is formed by sputtering. Thereafter, P was through-doped by ion implantation so as to have a dose of 5 × 10 ¹⁵ cm ⁻² to form a source / drain 35. The implantation is not limited to ion implantation, and PH _X may be implanted by plasma doping. After the injection, it was heated at 600 ° C. for 5 hours for activation. This becomes (C) of FIG.

  Then, an interlayer insulating film 38 is formed, and an extraction wiring electrode 39 for the gate electrode 37 and an extraction wiring electrode 40 for the source / drain 35 are formed. A top gate type polysilicon thin film transistor was completed. This is shown in FIG.

The completed TFT is an N-channel type having a channel length of 8 μm and a channel width of 100 μm. Regardless of the manufacturing method, the threshold voltage was approximately 1.0V. In order to perform a reliability test, a source-drain voltage of 11 V and a gate-source voltage of 14 V were applied and left in an N ₂ atmosphere at 150 ° C. for 10 hours, and before and after the measurement.

It shows the V _G ─I _D measurement results before and after the reliability test of the TFT in FIG. The horizontal axis shows the linear value of the gate voltage, and the vertical axis shows the logarithm of the absolute value of the drain current. Each unit is an arbitrary unit. This example of the method 1 and method 2 using the present invention showed almost the same characteristic 41. The on-current was 7.8 mA, and the mobility was 114 cm ² / Vsec. Even after the reliability test, the deterioration was a change that could not be confirmed, and the TFT characteristics were good.

This example using the present invention in Method 3 showed characteristic 42. The on-current was 8.5 mA, and the mobility was 120 cm ² / Vsec. Even after the reliability test, the deterioration was so good that it could not be confirmed.

In the case of the method 4 not using the present invention, the characteristic 43 is shown. The on-current was 7.0 mA, and the mobility was 100 cm ² / Vsec. After the reliability test, the characteristic 44 was exhibited, the on-current was 5.0 mA, and the mobility was reduced to 70 cm ² / Vsec. By using the present invention before forming the TFT gate insulating film, the TFT having high initial characteristics and high reliability can be formed by cleaning the interface between the active layer and the gate insulating film.

  A memory of a nonvolatile semiconductor memory device is configured by a large number of basic one memory transistors. The present invention was used to manufacture the memory transistor. FIG. 5 shows a basic cross-sectional structure of the memory transistor. On a P-type silicon substrate 51, a tunnel oxide film 52, a floating gate 53 made of polysilicon, an interlayer insulating film 54, a resist patterning and etching technique using a known silicon thermal oxidation technique, a CVD method and a photolithography technique, A polysilicon two-layer gate comprising a control gate 55 made of polysilicon. A memory transistor is formed including a source diffusion layer 57 and a drain diffusion layer 56 formed by ion implantation of phosphorus or arsenic.

The floating gate 53 is a gate for changing the threshold value of the memory transistor as viewed from the control gate 55.
When hot electrons are accumulated in the floating gate 53, the positive potential applied to the control 55 is canceled out by the hot electrons accumulated in the floating gate 53, so that the control gate is compared with a state in which no hot electrons are accumulated. The threshold value of the memory transistor viewed from 55 becomes higher. Hot electrons are injected into the floating gate 53 by applying 10, 5, and 0 V to the control gate 55, the drain 56, and the source 57, respectively.

  Some of the electrons moving through the channel of the memory transistor pass through the tunnel oxide film 52 and reach the floating gate 53 to be accumulated. The state in which hot electrons are accumulated in the floating gate 53 is in the write state, and conversely, the hot electrons are discharged from the floating gate 53 with the drain 56 electrically opened, and the source 57 and the control gate having 5 − This is done by applying 16V.

  As a result, a Fowler Nordheim current that is a tunnel current of the tunnel oxide film 52 in the overlap region 58 of the source 57 and the floating gate 53 is generated, and electrons are excluded from the floating gate 53 via the tunnel oxide film 52. A state in which hot electrons are not accumulated in the floating gate 53 is called a data erasure state.

  In this memory transistor, those involved in charge accumulation are the interlayer insulating film 54 and the tunnel oxide film 52 that are in contact with the floating gate 53 and the control gate 55, and it is natural that the configuration of the interface becomes important. is there. The present invention was used for cleaning the interface. Carbon removal by a catalytic method was performed before and after the formation of the control gate 55 and before and after the formation of the interlayer insulating film 54.

  As a method for performing the treatment by the catalytic method, the substrate 51 was disposed on the heating zone side of the heat treatment apparatus of the horizontal heating furnace.

  The catalyst is also located in the heating zone. Catalysts include platinum, palladium, reduced nickel, cobalt, titanium, panadium, tantalum and other 3d transition metals or aluminum, nickel, platinum / silicon, platinum / chlorine, platinum / rhenium, nickel / molybdenum, cobalt / molybdenum, Or a mixture or compound of the above transition metal and alumina, silica gel or the like, or Raney cobalt, ruthenium, palladium, nickel, etc. or a mixture or compound of these and carbon is suitable. Use in cotton or powder form.

  However, substances that have a low melting point and significantly increase the initial adsorption rate of the reactive substance, and substances containing an alkali metal such as sodium that are easily vaporized in the substance, such as copper and tungsten, are not preferable. According to the experiment, the catalyst was significantly deteriorated above the decomposition temperature of the reactive substance. The amount and density of the catalyst are related to the effective contact area with the reactive gas, and may be adjusted as necessary. In this example, 10% by weight of palladium mixed with alumina was used as a catalyst with a large surface area.

  In addition, an ultraviolet irradiation device for generating ozone is provided in front of the heating zone. The gas can be used at a reduced pressure of about normal pressure to about 500 Torr. When hydrogen and oxygen are introduced, ozone is first generated from the oxygen by ultraviolet irradiation, and hydrogen that touches the catalyst becomes active hydrogen radicals, and the ozone and hydrogen radicals reach the substrate 51. The appropriate distance between the ultraviolet irradiation and the catalyst and the substrate 31 is about 50 mm to 1 m. This distance can be made to flow uniformly on the surface of the substrate 31, and the life of hydrogen radicals and ozone is sufficiently long.

  By heating the heating zone to 300 to 700 ° C., hydrogen radicals can be formed by catalytic reaction. When the temperature was set to 700 ° C. or higher, the catalyst was significantly deteriorated. However, since the temperature varies depending on the catalyst used, it is necessary to adjust the temperature depending on the catalyst used. In this embodiment, hydrogen 100 SCCM, oxygen 100 SCCM, and a heating zone temperature of 500 ° C. were used. The time may be about 1 to 30 minutes. In this example, the time was 10 minutes.

In addition to generating hydrogen radicals and oxygen radicals using hydrogen and oxygen, H ₂ O can also be used. There are several ways to introduce H ₂ O. A tank containing H ₂ O is bubbled using an inert gas such as He, Ne, or Ar as a carrier gas, thereby carrying H ₂ O as a gas to the processing chamber. There is also a method in which the entire tank from the tank containing H ₂ O to the processing chamber is heated, the vapor pressure of H ₂ O is increased, and the processing chamber is bulged as it is. The introduced H ₂ O is decomposed by the plasma and simultaneously generates hydrogen ions, hydrogen radicals, oxygen ions, oxygen radicals, and ozone.

In the applicant's experiment, the same effect was observed even when bubbling a tank containing H ₂ O with N ₂ 50SCCM as the carrier gas.

  When the characteristics of the memory transistor formed as a flash memory were evaluated, the error rate of the memory after 150 rewrites was not used when the case where the present invention was used and the case where the memory transistor was not used were compared. In the case of 0.1%, it was reduced by 0.01% to 0.01% by using the present invention. Performing carbon removal according to the present invention has a great effect on the laminated structure of the crystalline semiconductor.

  An example in which the present invention is applied to a thin film transistor (also referred to as TFT) using polysilicon is shown in FIG. A process of forming the base film 302 over the glass substrate 301 is shown in FIG. 6A. The glass substrate 301 is made of a material having high translucency with respect to visible light such as borosilicate glass or quartz. Use. In this example, Corning 7059 glass from Corning was used.

  When the base film 302 is formed, when the gate voltage is increased in the ON direction after the TFT is completed using the present invention, carriers that flow under the channel, for example, the channel is an N-channel type. For example, carriers flowing through the channel are electrons, and if the channel is a P-channel type, the carrier flowing through the channel is a hole. However, when the gate voltage is increased in the ON direction, Something like a mold channel may occur.

When the channel is turned on, the drain current when the gate voltage is increased is saturated even if the gate voltage is increased. However, when a reverse channel is generated on the substrate 301 side below the channel, The drain current rises rapidly, and the drain current with respect to the gate voltage has a stage. A so-called kink effect occurs. By using the present invention when forming the base film 302, the occurrence of the kink effect is prevented or reduced. If the base film 302 is made of SiO _x containing no impurities, the occurrence of the kink effect is reduced.

  The base film 302 was formed by using tetraethyl silicate (also referred to as TEOS), oxygen, and hydrogen using a parallel plate plasma CVD apparatus. It is also effective to use organic silanes such as OMCTS (Octamethylcyclotetrasiloxane) and HMDS (Hexamethyldisiloxane) instead of regular tetraethyl silicate.

The substrate temperature was 200 to 500 ° C., typically 400 ° C., and the film forming pressure was set to 0.1 to 2 Torr and typically 1 Torr. A high frequency of 5 to 50 MHz is used as the plasma power source, but typically 20 MHz is used. The power supply of the plasma power source was 0.1 to ² W / cm ² , but typically 0.3 W / cm ² . The ratio of normal tetraethyl silicate to oxygen was normal tetraethyl silicate: oxygen = 1: 5 to 20, and the ratio was typically tetraethyl silicate: oxygen = 1: 5. The amount of hydrogen was in the range of normal tetraethyl silicate: hydrogen = 1: 0.01 to 1, but typically, normal tetraethyl silicate: hydrogen = 1: 0.5. Although the base film 302 was formed in a thickness of 500 to 3000 mm, typically 2000 mm was formed.

  In addition to the parallel plate plasma CVD, the base film 302 is formed by another plasma CVD method. When an oxide film is formed using organosilane, carbon in the film is removed by hydrogen radicals and hydrogen ions. This is very effective and is effective in any plasma CVD method.

  Also, when the base film 302 is formed by atmospheric pressure CVD, it is possible to remove carbon during film formation by generating hydrogen radicals by the catalytic method and using them during film formation. The present invention is also effective in the atmospheric pressure CVD method using organosilane. When the present invention is used for film formation using atmospheric pressure CVD, a catalytic method is used to convert hydrogen into hydrogen radicals.

  Catalysts include 3d-transition metals such as platinum, palladium, reduced nickel, cobalt, titanium, panadium, and tantalum, or aluminum, nickel, platinum / silicon, platinum / chlorine, platinum / rhenium, nickel / molybdenum, cobalt / molybdenum, etc. Or a mixture or compound of the above transition metals and alumina, silica gel, or the like, or Raney cobalt, ruthenium, palladium, nickel, or the like or a mixture or compound of these with carbon is suitable. Use in state.

  However, substances that have a low melting point and significantly increase the initial adsorption rate of the reactive substance, and substances containing an alkali metal such as sodium that are easily vaporized in the substance, such as copper and tungsten, are not preferable. According to the experiment, the catalyst was significantly deteriorated above the decomposition temperature of the reactive substance. The amount and density of the catalyst are related to the effective contact area with the reactive gas, and may be adjusted as necessary.

  Active hydrogen radicals are generated by passing hydrogen through a heated catalyst. Oxygen generates active ozone by passing through an ozonizer. In an atmospheric pressure CVD apparatus in which the substrate is heated, a tank containing normal tetraethyl silicate is bubbled with a carrier gas such as nitrogen, oxygen is introduced through an ozonizer, and hydrogen is introduced through a catalyst.

  All gases are mixed and supplied onto the substrate from a gas nozzle having a diffusion mechanism. When film formation is performed only with normal tetraethyl silicate and ozone in atmospheric pressure CVD, there is a great difference in the oxide film formed between the case where the surface is hydrophilic and the case where it is hydrophobic. A clean film can be formed on a substrate having a hydrophobic surface, but an abnormal film formation or a decrease in film formation speed tends to occur on a hydrophilic surface.

In the present invention involving hydrogen radicals, it is possible to form a hydrophobic surface by terminating active hydrogen on the substrate surface, together with the decarbonizing effect, and to prevent abnormal film formation and decrease in film formation rate. In particular, when hydrogen is introduced in an amount of about 0.01 to 0.2 times that of the N ₂ carrier gas, the effect is great. Great effect.

  FIG. 6B shows a structure in which an amorphous silicon film is formed as an active layer 303 on a substrate 301 on which a base film 302 is formed. The amorphous silicon has a thickness of about 50 to 3000 mm, and typically has a thickness of 400 to 1000 mm. As a film formation method, a plasma CVD method, a low pressure thermal CVD method, a sputtering method, or the like was used.

  In this example, silane was decomposed by a plasma CVD method, and a film was formed at a substrate temperature of 200 to 400 ° C., typically 250 to 350 ° C. Thereafter, amorphous silicon is so-called solid phase grown to be polycrystallized (polysilicon). The method is disclosed in JP-A-6-232059, JP-A-6-244103 and JP-A-6-244104 by the present applicant. By using the described invention, solid phase growth can be performed at 600 ° C. or lower.

  If the hydrogen in the amorphous silicon is not removed to some extent before solid-phase growth, hydrogen will suddenly go out of the amorphous state due to heating during solid-phase growth, so if it is severe, there will be a hole. Sometimes. Therefore, it is effective to put a hydrogen desorption step in nitrogen at 400 to 500 ° C. for 0.5 to 5 hours before solid phase growth. Typically performed at 400 ° C. for 1-2 hours in nitrogen.

  When solid-phase growth is performed, a problem of so-called shrinkage occurs in which the substrate shrinks due to a heat cycle, except that the substrate 301 has a high strain point such as quartz. This shrinkage can be avoided to some extent by raising the temperature once in advance and performing the subsequent processes below that temperature.

  In other words, this shrinkage countermeasure is taken at the same time when solid phase growth is performed. By using the invention described in JP-A-6-232059, JP-A-6-244103, and JP-A-6-244104 by the present applicant, solid phase growth can be performed at 600 ° C. or lower. Growth is also possible.

  In order to perform solid phase growth without using this method, a solid phase growth time of 4 to 24 hours at 600 ° C. is required. After the solid phase growth is completed, the active layer 303 changes from amorphous silicon to polysilicon. If the active layer 303 has a small amount of amorphous component in the polysilicon, a laser is applied to the active layer 303. It is also effective to cause laser crystallization by irradiation.

It is also effective to change the active layer 303 from amorphous silicon to polysilicon by irradiating a laser after the hydrogen extraction step without performing solid phase growth by heat. As a laser condition, a so-called excimer laser such as ArF, ArCl, KrF, KrCl, XeF, or XeCl is used as a laser source. As the irradiation energy, the exit energy from the laser main body is 400 to 1000 mJ, the laser is processed by an optical system, and the surface of the substrate 301 is irradiated at about 150 to 500 mJ / cm ² . The energy is the energy per one time of the laser. The substrate temperature is heated to room temperature to 300 ° C. The repetition frequency of irradiation is about 20 to 100 Hz, the moving speed of the laser on the substrate 301 is 1 to 5 mm / second, and the stage is moved by scanning the beam or placing the substrate 301 on the moving stage. .

In this embodiment, a stage on which the substrate 301 is mounted using a KrF excimer laser with a main body outlet output of 550 to 650 mJ, 180 to 230 mJ / cm ² on the substrate 301, and an irradiation repetition frequency of 35 to 45 HZ. It was moved at a speed of 2.0 to 3.0 mm / sec.

FIG. 6C shows an island 304 formed by patterning the active layer 303 after the active layer 303 on the substrate 301 on the base film 302 is changed from amorphous silicon to polysilicon. The patterning of the active layer 303 is performed by patterning a resist using known photolithography, and then etching the active layer 303 using the resist as a mask to form an island 304. Etching includes wet etching and dry etching. In this embodiment, a parallel plate high-frequency plasma processing apparatus using CF ₄ and O ₂ is used.

  FIG. 6D shows a gate insulating film 305 formed so as to cover the island 304. Since the interface between the island 304 and the gate insulating film 305 greatly affects the characteristics of the final TFT, the present invention is used to form the gate insulating film 305 itself. Cleaning becomes very important.

  In order to clean the surface of the island 304, sulfuric acid: hydrogen peroxide solution = 1: 1 is heated to 80 ° C. and immersed in it for 5 to 10 minutes to remove carbon contaminants to some extent, and then hydrochloric acid: peroxide Hydrogen oxide water = 1: 1 is heated to 80 ° C. and immersed therein for 5 to 10 minutes to remove heavy metals. If such cleaning affects the substrate 301 or the like, the cleaning is not performed. After that, the substrate 301 is placed in the plasma processing apparatus in order to remove carbon contaminants including at least a part of carbon single bonds from the surface of the island 304.

  Since the gate insulating film 305 is formed after the surface of the island 304 is cleaned, in this plasma processing apparatus, the plasma processing for forming the gate insulating film 305 includes at least a part of carbon single bond. It is desirable that the plasma treatment for removing the carbon contaminants can be performed in the same reaction chamber. By doing so, the gate insulating film 305 can be formed without exposing the island 304 having a clean surface to the atmosphere.

  As a plasma processing apparatus for removing carbon contaminants, which includes at least a part of the gate insulating film 305 and carbon single bond, a parallel plate type plasma CVD apparatus or an electron There are a microwave plasma CVD apparatus using cyclotron resonance, an electrodeless discharge plasma CVD apparatus in which electrodes are arranged around a quartz chamber, and the like. In the present embodiment, a plasma treatment for removing carbon contaminants contained in at least a part of carbon single bonds in accordance with [Method 1] of Embodiment 1 using a parallel plate type plasma CVD apparatus. I do.

  A substrate 301 on which an island 304 is formed is disposed on the anode side of a parallel plate type plasma processing apparatus. The electrode interval between the anode and the cathode, which are parallel plate electrodes, was adjusted between 30 and 150 mm. Typically performed at 70 mm.

The same amount of hydrogen gas and oxygen gas was introduced. In this example, the residence time was about 4 seconds with a chamber volume of 40 liters, a processing pressure of 1 Torr, oxygen of 400 SCCM, and hydrogen of 400 SCCM. In order to generate plasma by high frequency discharge, 10 to 100 MHz was used as the frequency of the high frequency, but 20 MHz was used in the examples. As the applied power, 0.1 to ² W / cm ² was input. In this example, 0.8 W / cm ² was charged.

  When the substrate temperature is about 200 to 500 ° C., the removal capability increases. In this embodiment, the process is performed at 300 to 400 ° C. in order to make the substrate temperature similar when the gate insulating film 305 is subsequently formed.

  The plasma processing time is about 1 to 10 minutes. This varies greatly depending on various conditions (gas residence time, high frequency, input power, substrate temperature), but taking too much time is not preferable as a manufacturing process. In this example, it was performed for 2 minutes.

  A gate insulating film 305 is formed after the step for removing carbon contaminants including at least a part of carbon single bonds. The gate insulating film 305 was formed using normal tetraethyl silicate (also referred to as TEOS), oxygen, and hydrogen.

  It is also effective to use organic silanes such as OMCTS (Octamethylcyclotetrasiloxane) and HMDS (Hexamethyldisiloxane) instead of regular tetraethyl silicate.

The substrate temperature is 200 to 500 ° C., typically 300 to 400 ° C. The film formation pressure was set to 0.1 to 2 Torr, and typically 0.5 to 1 Torr. A high frequency of 5 to 50 MHz is used as the plasma power source, but typically 20 MHz is used. The supply power of the plasma power source was 0.1 to ² W / cm ² , but typically 0.3 to 0.5 W / cm ² .

The ratio of normal tetraethyl silicate to oxygen was normal tetraethyl silicate: oxygen = 1: 5 to 20, typically, normal tetraethyl silicate: oxygen = 1: 10. The amount of hydrogen was in the range of normal tetraethyl silicate: hydrogen = 1: 0.01 to 1, but typically, normal tetraethyl silicate: hydrogen = 1: 0.5. The gate insulating film 305 is formed in a thickness of 250 to 2000 mm, but typically 500 to 1200 mm. The carbon during film formation is gasified in the form of CH _X or COH by the hydrogen radicals and hydrogen ions and exhausted out of the chamber.

After completion of the process, the amount of carbon in the gate insulating film 305 was measured by SIMS. As a result, in the profile in the depth direction of carbon in the oxide film as the gate insulating film 305 formed without adding hydrogen. In the profile in the depth direction of carbon in the oxide film as the gate insulating film 305 formed by adding hydrogen, whereas the lowest value was 1 × 10 ¹⁹ cm ⁻³ , The lowest value was 2 × 10 ^{18 to} 7 × 10 ¹⁸ cm ⁻³ .

  A gate electrode film is formed on the gate insulating film 305 and patterned to form a gate electrode 306, and then an impurity region for forming a source / drain 307 is formed to form FIG. E).

  After laminating Al, doped polysilicon, Cr, Ta, etc. as a conductive film, the resist is patterned by a photolithography process, and the conductive film is etched into a desired shape to produce a gate electrode 306. To do. In this embodiment, polysilicon is formed by a low pressure CVD method.

Thereafter, P was through-doped by ion implantation so as to have a dose of 5 × 10 ¹⁵ cm ⁻² to form a source / drain 307. The implantation is not limited to ion implantation, and PH _X may be implanted by plasma doping. After the injection, it was heated at 600 ° C. for 5 hours for activation. In order to form the gate electrode 306 with polysilicon, doped polysilicon may be formed. However, after forming the non-doped polysilicon, ion implantation or plasma for forming the source / drain 307 is performed. Doped polysilicon can be obtained by doping.

  Thereafter, an interlayer insulating film 308 is formed, and a lead-out wiring electrode 309 for the gate electrode 306 and a lead-out wiring electrode 310 for the source / drain 307 are formed. A top gate type polysilicon thin film transistor was completed. This is shown in FIG. The present invention was used when the interlayer insulating film 308 was formed. Even when the interlayer insulating film 308 is formed by atmospheric pressure CVD, it is possible to remove carbon during film formation by generating hydrogen radicals using the catalytic method and using them also during film formation. The present invention is also effective in the atmospheric pressure CVD method using organosilane.

  When the present invention is used for film formation using atmospheric pressure CVD, a catalytic method is used to convert hydrogen into hydrogen radicals. Catalysts include 3d-transition metals such as platinum, palladium, reduced nickel, cobalt, titanium, panadium, and tantalum, or aluminum, nickel, platinum / silicon, platinum / chlorine, platinum / rhenium, nickel / molybdenum, cobalt / molybdenum, etc. Or a mixture or compound of the above transition metals and alumina, silica gel, or the like, or Raney cobalt, ruthenium, palladium, nickel, or the like or a mixture or compound of these with carbon is suitable. Use in state.

  However, substances that have a low melting point and significantly increase the initial adsorption rate of the reactive substance, and substances containing an alkali metal such as sodium that are easily vaporized in the substance, such as copper and tungsten, are not preferable. According to the experiment, the catalyst was significantly deteriorated above the decomposition temperature of the reactive substance.

The amount and density of the catalyst are related to the effective contact area with the reactive gas, and may be adjusted as necessary. Active hydrogen radicals are generated by passing hydrogen through a heated catalyst. Oxygen generates active ozone by passing through an ozonizer. In a normal pressure CVD apparatus in which the substrate is heated, a tank containing normal tetraethyl silicate is bubbled with a carrier gas such as nitrogen, oxygen is introduced through an ozonizer, and hydrogen is introduced through a catalyst. All gases are mixed and supplied onto the substrate from a gas nozzle having a diffusion mechanism. When hydrogen is introduced in an amount of about 0.1 to ₂ times that of the N ₂ carrier gas, the effect is large, and when normal tetraethyl silicate is heated and directly gasified, the effect is about 1 to 5 times greater.

In this example, Ni was used to generate hydrogen radicals from hydrogen at a catalyst temperature of 500 ° C. The amount of hydrogen was 0.3 to 0.8 times that of the N ₂ carrier gas. A film of 7000 to 15000 mm was formed at a substrate temperature of 350 ° C. Typically, the film was formed at 9000 to 12000 mm. After the interlayer insulating film 308 was formed, hydrogenation treatment was performed.

  Hydrogenation was performed by thermal hydrogenation or plasma hydrogenation. In this example, thermal hydrogenation was performed. The conditions were a substrate temperature of 250 to 400 ° C. and a normal pressure of 100% hydrogen for 1 to 5 hours.

  In this embodiment, the base film 302, the gate insulating film 305, and the interlayer insulating film 308 are all formed of an oxide film using organosilane, and the present invention is used for all the film formation. The present invention may be applied only to the gate insulating film 305, or only the interlayer insulating film 308. This is because the present invention removes carbon during film formation from the organosilane system, and therefore the present invention does not have to be used for film formation without using organosilane. In addition to this, the present invention need not be used in order to emphasize other film characteristics in addition to reducing the amount of carbon.

  Therefore, an oxide film using the present invention may be formed for the base film 302 and the interlayer insulating film 308, and a thermal oxide film or a film using silane and oxygen may be used for the gate insulating film 305. . There are many other combinations possible. Further, the present invention is used before the gate insulating film 305 is formed, but this is an effective method for any gate insulating film, and it is better to use it as much as possible among various combinations. .

Using the present invention, the completed TFT, the characteristics are the channel length 8μm channel width 100μm is 153cm ² / Vsec mobility is N-channel type, large and 119cm ² / Vsec in P-channel type, also kink No effect was observed. As for moisture resistance, no change in characteristics was observed after standing at 150 ° C. and 60% RH for 12 hours. Originally, if a protective film of SiN _x is provided on this TFT, the moisture resistance is further improved. Since all of the base film 302, the gate insulating film 305, and the interlayer insulating film 308 are significantly less in carbon than the case where the present invention is not used, it is possible to improve TFT characteristics and reliability. .

In contrast to crystallization of the active layer 303 shown in FIG. 6, the activity using lateral crystal growth described in Japanese Patent Application Laid-Open No. 7-74366 (Japanese Patent Application No. 6-131416) by the present applicant. Layer 303 was utilized. This utilizes the fact that a nickel silicide film (NiSi _x , 0.4 ≦ X ≦ 2.5) is selectively formed on the base film 301 and crystallization grows laterally therefrom.

By using this method, the crystal grains grow largely horizontally, and by using the present invention, impurities such as single bonds of carbon are removed from the interface between the gate insulating film 305 and the island 304. Has been. Consequently, as the TFT characteristic, a and its characteristics are the channel length 8μm channel width 100 [mu] m, 170cm ² / Vsec mobility is N-channel type, as large as 130 cm ² / Vsec in P-channel type, also kink effect is observed at all Was not. As for moisture resistance, no change in characteristics was observed after standing at 150 ° C. and 60% RH for 12 hours.

  FIG. 7 shows another embodiment using the present invention. A process of forming the base film 402 over the glass substrate 401 is shown in FIG. 7A. The glass substrate 401 is made of a material having high translucency with respect to visible light such as borosilicate glass or quartz. Use. In this example, Corning 7059 glass from Corning was used.

The base film 402 was formed by using tetraethyl silicate (also referred to as TEOS), oxygen, and hydrogen using a parallel plate plasma CVD apparatus. The substrate temperature was 200 to 500 ° C., typically 400 ° C., and the film forming pressure was set to 0.1 to 2 Torr and typically 1 Torr. A high frequency of 5 to 50 MHz is used as the plasma power source, but typically 20 MHz is used. The power supply of the plasma power source was 0.1 to ² W / cm ² , but typically 0.3 W / cm ² . The ratio of normal tetraethyl silicate to oxygen was normal tetraethyl silicate: oxygen = 1: 5 to 20, and the ratio was typically tetraethyl silicate: oxygen = 1: 5. Although the base film 402 was formed in a thickness of 500 to 3000 mm, typically 2000 mm was formed.

  FIG. 7B shows a structure in which an amorphous silicon film is formed as an active layer 403 on a substrate 401 over which a base film 402 is formed. The amorphous silicon has a thickness of about 50 to 3000 mm, and typically has a thickness of 400 to 1000 mm. As a film formation method, a plasma CVD method, a low pressure thermal CVD method, a sputtering method, or the like was used.

  In this example, silane was decomposed by a plasma CVD method, and a film was formed at a substrate temperature of 200 to 400 ° C., typically 250 to 350 ° C. Thereafter, amorphous silicon is so-called solid phase grown to be polycrystallized (polysilicon). If the hydrogen in the amorphous silicon is not removed to some extent before solid-phase growth, hydrogen will suddenly go out of the amorphous state due to heating during solid-phase growth, so if it is terrible, there will be holes. Sometimes. Therefore, it is effective to put a hydrogen desorption step in nitrogen at 400 to 500 ° C. for 0.5 to 5 hours before solid phase growth. Typically performed at 400 ° C. for 1-2 hours in nitrogen.

  When solid phase growth is performed, a problem of so-called shrinkage occurs in which the substrate shrinks due to a heat cycle, except that the substrate 401 has a high strain point such as quartz. This shrinkage can be avoided to some extent by raising the temperature once in advance and performing the subsequent processes below that temperature. In other words, this shrinkage countermeasure is taken at the same time when solid phase growth is performed.

  After the solid phase growth is completed, the active layer 403 changes from amorphous silicon to polysilicon, but when the active layer 403 has a small amount of amorphous component in the polysilicon, a laser is applied to the active layer 403. It is also effective to cause laser crystallization by irradiation.

It is also effective to change the active layer 403 from amorphous silicon to polysilicon by irradiating a laser after the hydrogen extraction step without performing solid phase growth by heat. For example, using a KrF excimer laser, a stage on which the substrate 401 is placed at a main body outlet output of 550 to 650 mJ, 180 to 230 mJ / cm ² on the substrate 401, and an irradiation repetition frequency of 35 to 45 HZ is 2.0. It may be moved at a speed of ˜3.0 mm / second.

FIG. 7C illustrates an island 404 formed by patterning the active layer 403 after the active layer 403 over the base film 402 on the substrate 401 is changed from amorphous silicon to polysilicon. The patterning of the active layer 403 is performed by patterning a resist using known photolithography, and then etching the active layer 403 using the resist as a mask to form an island 404. Etching includes wet etching and dry etching. In this embodiment, a parallel plate high-frequency plasma processing apparatus using CF ₄ and O ₂ is used.

  FIG. 7D shows a structure in which a gate insulating film 405 is formed to cover the island 404. Since the interface between the island 404 and the gate insulating film 405 greatly affects the characteristics of the final TFT, the present invention is used to form the gate insulating film 405 itself. Cleaning becomes very important.

  In order to clean the surface of the island 404, sulfuric acid: hydrogen peroxide solution = 1: 1 is heated to 80 ° C. and immersed in it for 5 to 10 minutes to remove carbon contaminants to some extent, and then hydrochloric acid: excess Hydrogen oxide water = 1: 1 is heated to 80 ° C. and immersed therein for 5 to 10 minutes to remove heavy metals. If such cleaning affects the substrate 401 or the like, the cleaning is not performed. After that, the substrate 401 is placed in the plasma processing apparatus in order to remove carbon contaminants that include at least a part of carbon single bonds from the surface of the island 404.

  In this embodiment, a parallel plate type plasma CVD apparatus is used, and at least part of carbon single bonds on the surface of the island 404 are included in accordance with the conditions of [Method 1] in Embodiment 1 as in Embodiment 3. Remove carbon contamination

A gate insulating film 405 is formed after the step for removing carbon contaminants. The gate insulating film 405 was formed using normal tetraethyl silicate (also referred to as TEOS), oxygen, and hydrogen. The substrate temperature is 200 to 500 ° C., typically 300 to 400 ° C. The film formation pressure was set to 0.1 to 2 Torr, and typically 0.5 to 1 Torr. A high frequency of 5 to 50 MHz is used as the plasma power source, but typically 20 MHz is used. The supply power of the plasma power source was 0.1 to ² W / cm ² , but typically 0.3 to 0.5 W / cm ² . The ratio of normal tetraethyl silicate to oxygen was normal tetraethyl silicate: oxygen = 1: 5 to 20, typically, normal tetraethyl silicate: oxygen = 1: 10. The amount of hydrogen was in the range of normal tetraethyl silicate: hydrogen = 1: 0.1 to 10, but typically, normal tetraethyl silicate: hydrogen = 1: 5. The gate insulating film 405 is formed in a thickness of 250 to 2000 mm, but typically 500 to 1200 mm. The carbon during film formation is gasified in the form of CH _X or COH by the hydrogen radicals and hydrogen ions and exhausted out of the chamber. After completion of the process, the amount of carbon in the gate insulating film 405 was measured by SIMS. As a result, in the profile in the depth direction of carbon in the oxide film as the gate insulating film 405 formed without adding hydrogen. In the profile in the depth direction of carbon in the oxide film as the gate insulating film 405 formed by adding hydrogen, whereas the lowest value was 1 × 10 ¹⁹ cm ⁻³ . The lowest value was 2 × 10 ^{18 to} 7 × 10 ¹⁸ cm ⁻³ .

Since the gate insulating film 405 is formed by adding hydrogen or H ₂ O, hydrogenation, which is an essential process in a TFT using polysilicon, is simultaneously performed in this process. It can also be done. An oxide film in which the gate insulating film 405 is formed by adding hydrogen to normal tetraethyl silicate and oxygen has a good step coverage, a low carbon content, and plasma hydrogenation. In order to prevent hydrogen from escaping from this hydrogenated polysilicon, a film containing nitrogen such as SiN _x or SiO _x N _y is formed thereon to prevent hydrogen escaping. It is possible to eliminate hydrogenation in the process.

A gate electrode film is formed on the gate insulating film 405 and patterned to form a gate electrode 406, and then an impurity region for forming a source / drain 407 is formed to form FIG. E). After laminating Al, doped polysilicon, Cr, Ta, etc. as a conductive film, the resist is patterned by a photolithography process, and the conductive film is etched into a desired shape to produce a gate electrode 406. To do. In this embodiment, Al is formed by sputtering. Thereafter, P was through-doped by ion implantation so as to have a dose of 5 × 10 ¹⁵ cm ⁻² to form a source / drain 407. The implantation is not limited to ion implantation, and PH _X may be implanted by plasma doping. After the injection, it was heated at 600 ° C. for 5 hours for activation. In order to form the gate electrode 406 with polysilicon, doped polysilicon may be formed. However, after forming the non-doped polysilicon, ion implantation or plasma for forming the source / drain 407 is performed. Doped polysilicon can be obtained by doping.

Thereafter, a nitride film 408 was formed as a first protective film on the entire surface of the substrate by a plasma CVD method or a sputtering method by 500 to 3000 mm. The interlayer insulating film 409 is formed, and the extraction wiring electrode 410 for the gate electrode 406 and the extraction wiring electrode 411 for the source / drain 407 are formed. A top gate type polysilicon thin film transistor was completed. This is shown in FIG. When the gate insulating film 405 is composed of two layers of an oxide film using the present invention and a film containing nitrogen such as SiN _x or SiO _x N _y , hydrogenation at this stage is not necessary, otherwise Here, hydrogenation is required.

Using the present invention, the completed TFT, the characteristics are the channel length 8μm channel width 100μm is 140cm ² / Vsec mobility is N-channel type, as large as 123 cm ² / Vsec in P-channel type, also kink No effect was observed. As for moisture resistance, no change in characteristics was observed after standing at 150 ° C. and 60% RH for 12 hours. Originally, if a protective film of SiN _x is provided on this TFT, the moisture resistance is further improved. Since all of the base film 302, the gate insulating film 305, and the interlayer insulating film 308 are significantly less in carbon than the case where the present invention is not used, it is possible to improve TFT characteristics and reliability. .

  FIG. 8 shows another embodiment using the present invention. A step of forming the base film 502 over the glass substrate 501 is shown in FIG. 8A. The glass substrate 501 is made of a material having high translucency with respect to visible light such as borosilicate glass or quartz. . In this example, Corning 7059 glass from Corning was used.

The base film 502 was formed using normal tetraethyl silicate (also referred to as TEOS) and oxygen using a parallel plate plasma CVD apparatus. The substrate temperature was 200 to 500 ° C., typically 400 ° C., and the film forming pressure was set to 0.1 to 2 Torr and typically 1 Torr. A high frequency of 5 to 50 MHz is used as the plasma power source, but typically 20 MHz is used. The power supply of the plasma power source was 0.1 to ² W / cm ² , but typically 0.3 W / cm ² . The ratio of normal tetraethyl silicate to oxygen was normal tetraethyl silicate: oxygen = 1: 5 to 20, and the ratio was typically tetraethyl silicate: oxygen = 1: 5. The base film 502 was formed in a thickness of 500 to 3000 mm, but typically 2000 mm.

  FIG. 8B illustrates a structure in which an amorphous silicon film is formed as the active layer 503 on the substrate 501 over which the base film 502 is formed. The amorphous silicon has a thickness of about 50 to 3000 mm, and typically has a thickness of 400 to 1000 mm. As a film formation method, a plasma CVD method, a low pressure thermal CVD method, a sputtering method, or the like was used. In this example, silane was decomposed by a plasma CVD method, and a film was formed at a substrate temperature of 200 to 400 ° C., typically 250 to 350 ° C. Thereafter, amorphous silicon is so-called solid phase grown to be polycrystallized (polysilicon). If the hydrogen in the amorphous silicon is not removed to some extent before solid-phase growth, hydrogen will suddenly go out of the amorphous state due to heating during solid-phase growth, so if it is terrible, there will be holes. Sometimes. Therefore, it is effective to put a hydrogen desorption step in nitrogen at 400 to 500 ° C. for 0.5 to 5 hours before solid phase growth. Typically performed at 400 ° C. for 1-2 hours in nitrogen.

  When solid phase growth is performed, a problem of so-called shrinkage occurs in which the substrate shrinks due to a heat cycle, except for the substrate 501 having a high strain point such as quartz. This shrinkage can be avoided to some extent by raising the temperature once in advance and performing the subsequent processes below that temperature. In other words, this shrinkage countermeasure is taken at the same time when solid phase growth is performed.

  After the solid phase growth is completed, the active layer 503 changes from amorphous silicon to polysilicon. When the active layer 503 has a small amount of amorphous component in the polysilicon, a laser is applied to the active layer 503. It is also effective to cause laser crystallization by irradiation.

  It is also effective to change the active layer 503 from amorphous silicon to polysilicon by irradiating a laser after the hydrogen extraction step without performing solid phase growth by heat.

As a laser condition, a so-called excimer laser such as ArF, ArCl, KrF, KrCl, XeF, or XeCl is used as a laser source. As the irradiation energy, the exit energy from the laser main body is 400 to 1000 mJ, the laser is processed by an optical system, and the surface of the substrate 501 is irradiated at about 150 to 500 mJ / cm ² . The energy is the energy per one time of the laser. The substrate temperature is heated to room temperature to 300 ° C. The repetition frequency of irradiation is about 20 to 100 Hz, the moving speed of the laser on the substrate 501 is 1 to 5 mm / second, and the stage is moved by scanning the beam or placing the substrate 501 on the moving stage. .

In this embodiment, a stage on which the substrate 501 is placed at a main body outlet output of 550 to 650 mJ, 180 to 230 mJ / cm ² on the substrate 501, and an irradiation repetition frequency of 35 to 45 Hz using a KrF excimer laser. It was moved at a speed of 2.0 to 3.0 mm / sec.

FIG. 7C shows an island 504 formed by patterning the active layer 503 after the active layer 503 on the substrate 501 on the base film 502 is changed from amorphous silicon to polysilicon. The patterning of the active layer 503 is performed by patterning a resist using known photolithography, and then etching the active layer 503 using the resist as a mask to form an island 504. Etching includes wet etching and dry etching. In this embodiment, a parallel plate high-frequency plasma processing apparatus using CF ₄ and O ₂ is used.

  A structure in which a gate insulating film 505 is formed to cover the island 504 is shown in FIG. Since the interface between the island 504 and the gate insulating film 505 greatly affects the characteristics of the final TFT, the present invention is used to form the gate insulating film 505 itself. Cleaning becomes very important.

  In order to clean the surface of the island 504, sulfuric acid: hydrogen peroxide solution = 1: 1 is heated to 80 ° C. and immersed in it for 5 to 10 minutes to remove carbon contaminants to some extent, and then hydrochloric acid: excess Hydrogen oxide water = 1: 1 is heated to 80 ° C. and immersed therein for 5 to 10 minutes to remove heavy metals. Such cleaning is not performed when the substrate 501 or the like is affected. After that, the substrate 501 is placed in the plasma processing apparatus in order to remove carbon contaminants contained in at least a part of the carbon single bond from the surface of the island 504.

  In this example, a parallel plate type plasma CVD apparatus was used, and at least a part of the carbon single bond was included according to the conditions of [Method 1] of Example 1 as in Example 3. Plasma treatment for removing contaminants is performed.

A gate insulating film 505 is formed after the step for removing carbon contaminants including at least a part of carbon single bonds. The gate insulating film 505 was formed using normal tetraethyl silicate (also referred to as TEOS), oxygen, and hydrogen. The substrate temperature is 200 to 500 ° C., typically 300 to 400 ° C. The film formation pressure was set to 0.1 to 2 Torr, and typically 0.5 to 1 Torr. A high frequency of 5 to 50 MHz is used as the plasma power source, but typically 20 MHz is used. The supply power of the plasma power source was 0.1 to ² W / cm ² , but typically 0.3 to 0.5 W / cm ² . The ratio of normal tetraethyl silicate to oxygen was normal tetraethyl silicate: oxygen = 1: 5 to 20, typically, normal tetraethyl silicate: oxygen = 1: 10. The amount of hydrogen was in the range of normal tetraethyl silicate: hydrogen = 1: 0.1 to 10, but typically, normal tetraethyl silicate: hydrogen = 1: 5. The gate insulating film 405 is formed in a thickness of 250 to 2000 mm, but typically 500 to 1200 mm.

The carbon during film formation is gasified in the form of CH _X or COH by the hydrogen radicals and hydrogen ions and exhausted out of the chamber. After completion of the process, the amount of carbon in the gate insulating film 505 was measured by SIMS. As a result, in the profile in the depth direction of carbon in the oxide film as the gate insulating film 505 formed without adding hydrogen. In the profile in the depth direction of carbon in the oxide film as the gate insulating film 505 formed by adding hydrogen, whereas the lowest value was 1 × 10 ¹⁹ cm ⁻³ . The lowest value was 2 × 10 ^{18 to} 7 × 10 ¹⁸ cm ⁻³ .

  On the gate insulating film 505, Al is formed as a gate electrode film and patterned, and then an anodic oxide film 507 for forming the offset region 509 is formed on the gate electrode 506, and then the source An impurity region for forming the drain 508 offset region 509 is formed, resulting in FIG.

  As the conductive film, Al may be a mixture of impurities or Ta that can be anodized. Anodization is a method in which a succinic acid solution or an oxalic acid aqueous solution is mixed with ethylene glycol or ammonia, and an electric current is applied using Al of the gate electrode 506 on the substrate 501 as an electrode and platinum as its counter electrode. An anodic oxide film 507 is formed on Al on the substrate 501.

Thereafter, P was through-doped by ion implantation so as to have a dose of 5 × 10 ¹⁵ cm ⁻² to form a source / drain 508 offset region 509. The implantation is not limited to ion implantation, and PH _X may be implanted by plasma doping. After the injection, it was heated at 600 ° C. for 5 hours for activation.

  Thereafter, an interlayer insulating film 510 is formed, and a lead-out wiring electrode 511 for the gate electrode 506 and a lead-out wiring electrode 512 for the source / drain 508 are formed. Hydrogenation is performed by heat or plasma to complete a top gate type polysilicon thin film transistor. This is shown in FIG.

Using the present invention, the completed TFT, the characteristics are the channel length 8μm channel width 100μm is 140cm ² / Vsec mobility is N-channel type, as large as 123 cm ² / Vsec in P-channel type, also kink No effect was observed. As for moisture resistance, no change in characteristics was observed after standing at 150 ° C. and 60% RH for 12 hours. Originally, if a protective film of SiN _x is provided on this TFT, the moisture resistance is further improved.

The graph which shows the removal degree of the carbon impurity by XPS of the substrate surface by this invention. The graph which shows the removal degree of the carbon impurity by XPS by the conventional technique. FIG. 6 is a cross-sectional view illustrating a process for forming a transistor in an example. It shows the V _G ─I _D measurement results before and after the reliability test of the TFT. FIG. 3 shows a basic cross-sectional structure of a memory transistor. The figure which shows the cross section of the formation process of the thin film semiconductor device in an Example. The figure which shows the cross section of the formation process of the thin film semiconductor device in an Example. The figure which shows the cross section of the formation process of the thin film semiconductor device in an Example.

Explanation of symbols

31 Glass substrate 32 Base film 33 Island 34 Gate insulating film 35 Source / drain 36 Channel 37 Gate electrode 38 Interlayer insulating film 39 Gate electrode lead-out wiring electrode 40 Source / drain lead-out electrode

Claims (19)

A method for manufacturing a semiconductor device having a semiconductor layer, a gate insulating film, and a gate electrode over an insulating substrate,
In the film formation step of the gate insulating film, at least using an organosilane source, activated oxygen, and activated hydrogen,
The amount of hydrogen introduced in the film forming step of the gate insulating film is Ri 0.01-0.5 Baidea amount of the organosilane source,
The method for manufacturing a semiconductor device, characterized in that the amount of oxygen introduced in the step of forming the gate insulating film is 5 to 20 times the amount of the organosilane source. A method for manufacturing a semiconductor device having a semiconductor layer, a gate insulating film, and a gate electrode over an insulating substrate,
Before forming the gate insulating film, the first activated hydrogen is brought into contact with the film forming surface,
In the film formation step of the gate insulating film, at least using an organosilane source, activated oxygen, and second activated hydrogen,
The amount of hydrogen introduced in the film forming step of the gate insulating film is Ri 0.01-0.5 Baidea amount of the organosilane source,
The method for manufacturing a semiconductor device, characterized in that the amount of oxygen introduced in the step of forming the gate insulating film is 5 to 20 times the amount of the organosilane source. A method for manufacturing a semiconductor device having a semiconductor layer, a gate insulating film, and a gate electrode over an insulating substrate,
Before forming the gate insulating film, the first activated oxygen is brought into contact with the film formation surface, and then the first activated hydrogen is brought into contact with the film formation surface,
In the gate insulating film formation step, at least an organosilane source, a second activated oxygen, and a second activated hydrogen are used,
The amount of hydrogen introduced in the film forming step of the gate insulating film is Ri 0.01-0.5 Baidea amount of the organosilane source,
The method for manufacturing a semiconductor device, characterized in that the amount of oxygen introduced in the step of forming the gate insulating film is 5 to 20 times the amount of the organosilane source. A method for manufacturing a semiconductor device having a semiconductor layer, a gate insulating film, and a gate electrode over an insulating substrate,
Before the gate insulating film is formed, after the first activated hydrogen is brought into contact with the film forming surface, the first activated oxygen is brought into contact with the film forming surface,
In the gate insulating film formation step, at least an organosilane source, a second activated oxygen, and a second activated hydrogen are used,
The amount of hydrogen introduced in the film forming step of the gate insulating film is Ri 0.01-0.5 Baidea amount of the organosilane source,
The method for manufacturing a semiconductor device, characterized in that the amount of oxygen introduced in the step of forming the gate insulating film is 5 to 20 times the amount of the organosilane source. A method for manufacturing a semiconductor device having a semiconductor layer, a gate insulating film, and a gate electrode over an insulating substrate,
Before forming the gate insulating film, a mixed gas of first activated hydrogen and first activated oxygen is brought into contact with the film forming surface,
In the gate insulating film formation step, at least an organosilane source, a second activated oxygen, and a second activated hydrogen are used,
The amount of hydrogen introduced in the film forming step of the gate insulating film is Ri 0.01-0.5 Baidea amount of the organosilane source,
The method for manufacturing a semiconductor device, characterized in that the amount of oxygen introduced in the step of forming the gate insulating film is 5 to 20 times the amount of the organosilane source. In claim 1,
Generation of the activated hydrogen is performed by a plasma method or a catalytic method,
A method for manufacturing a semiconductor device, wherein the generation of the activated oxygen is performed by a plasma method or an ultraviolet irradiation method. In claim 2,
Generating the first activated hydrogen and the second activated hydrogen by a plasma method or a catalyst method;
A method for manufacturing a semiconductor device, wherein the generation of the activated oxygen is performed by a plasma method or an ultraviolet irradiation method. In any one of Claims 3 thru | or 5,
Generating the first activated hydrogen and the second activated hydrogen by a plasma method or a catalyst method;
A method for manufacturing a semiconductor device, wherein generation of the first activated oxygen and the second activated oxygen is performed by a plasma method or an ultraviolet irradiation method. In claim 1 or claim 6,
The method for manufacturing a semiconductor device, wherein the activated hydrogen is hydrogen radical or a mixed gas of hydrogen radical and hydrogen ion. In any one of Claim 2 thru | or Claim 5, Claim 7, and Claim 8,
The method for manufacturing a semiconductor device, wherein the first activated hydrogen and the second activated hydrogen are hydrogen radicals or a mixed gas of hydrogen radicals and hydrogen ions. In any one of Claim 1, Claim 2, Claim 6, and Claim 7,
The method for manufacturing a semiconductor device, wherein the activated oxygen is any one of oxygen radicals, ozone, a mixed gas of oxygen radicals and oxygen ions, and a mixed gas of oxygen radicals, ozone, and oxygen ions. In any one of Claim 3 thru | or Claim 5 and Claim 8,
The first activated oxygen and the second activated oxygen are any of oxygen radicals, ozone, a mixed gas of oxygen radicals and oxygen ions, and a mixed gas of oxygen radicals, ozone and oxygen ions. A method for manufacturing a semiconductor device. In claim 5,
The method of manufacturing a semiconductor device, wherein the mixed gas is generated by decomposing H ₂ O. In any one of Claims 1 thru | or 13 ,
A method for manufacturing a semiconductor device, wherein the organosilane source is regular tetraethyl silicate. In any one of Claims 1 thru | or 14 ,
In the film formation step of the gate insulating film, the temperature of the insulating substrate is 200 to 500 ° C. In any one of Claims 1 thru | or 15 ,
The method for manufacturing a semiconductor device, wherein the gate insulating film is formed by a plasma CVD method or an atmospheric pressure CVD method. In any one of Claims 1 thru | or 16 ,
A method for manufacturing a semiconductor device, wherein the semiconductor layer is crystallized in a lateral direction. In any one of Claims 1 thru | or 17 ,
A method for manufacturing a semiconductor device, wherein the gate electrode is polysilicon. In any one of Claims 1 thru | or 18 ,
A method for manufacturing a semiconductor device, comprising forming a nitride film over the gate insulating film.

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