CN100479119C - Thin film transistor and manufacturing method thereof, display apparatus, method for modifying oxide film, method for forming oxide film, semiconductor device, method for manufacturing semiconductor d - Google Patents

Abstract

In a method for manufacturing a thin film transistor (1), a substrate (2) to be processed, on which the gate oxide film (4) is to be formed on a front plane, is impregnated with an oxidizing solution including an active oxidation seed to directly oxidize polysilicon (51) on the substrate (2), and the gate oxide film (4) is formed. Thus, a silicon dioxide film (42) is formed by growing a silicon dioxide film (41) in a direction of the substrate (2). Thus, an interface between the polysilicon (51) and the gate oxide film (4) is kept clean and the high-quality gate oxide film (4) having excellent dielectric breakdown strength can be uniformly formed. Therefore, the thin film transistor (1) having excellent dielectric breakdown strength can be formed at a low temperature with a high-quality oxide film provided thereon.

Description

The manufacture method of the formation method of the method for modifying of thin-film transistor and manufacture method thereof, display unit, oxide-film, oxide-film, semiconductor device, semiconductor device and the manufacturing installation of semiconductor device

Technical field

The present invention relates to the manufacture method and the application thereof of a kind of thin-film transistor (TFT), oxide-film that this method possessed forms operation and is suitable for forming that the special requirement of grid oxidation film (particularly silicon dioxide film) and so on for example are high-quality, the oxide-film of high reliability.

In addition, the present invention relates to the formation method of oxide-film, the manufacture method of semiconductor device and the manufacturing installation of semiconductor device, in more detail, relate to and be suitable for for example forming the formation method of the semiconductor oxide film of thin dielectric membrane (silicon dioxide film), the manufacture method of semiconductor device and the manufacturing installation of semiconductor device on the surfaces such as semiconductor surface, especially silicon substrate at low temperatures.

Background technology

Grid oxidation film (gate insulating film) is the important insulation film that constitutes TFT.In general, on the gate electrode of TFT, apply higher voltage.Therefore, grid oxidation film requires to possess insulating properties completely.Therefore, grid oxidation film forms with the thickness (about several 10～100nm) of certain degree, not cause leakage current.If the increase of leakage current density, not only can cause device to use the generation of following degradation variety of issue of rising, the stability of increase, the working temperature of power, and the work of under magnitude of leakage current reaches situation with drain current amount same degree, going back entail dangers to device self.

This shows that grid oxidation film can directly have influence on the performance (reliability, characteristic) of the various devices that possess TFT, therefore, it possesses high-quality, high reliability special requirement.

Generally speaking, the grid oxidation film among the TFT (for example silicon dioxide film) uses CVD method (chemical vapour deposition technique) to form usually.The CVD method be a kind of with organosilan, for example tetraethoxysilane (TEOS) etc. with after the hundreds of ℃ of thermal decompositions on substrate deposited oxide film form the method for grid oxidation film thus.

Except that said method, it is also known for the sputter evaporation form oxide the sputter vapour deposition method, in plasma, make the oxide-film formation methods such as plasma oxidation method of substrate surface oxidation.

In addition, known method also has by anodic oxidation makes the anode oxidation method that forms oxide-film after the substrate surface oxidation, for example, in hydrofluoric acid aqueous solution (electrolyte), apply voltage to silicon substrate, after forming porous matter anode reaction silicon fiml, this porous matter anode reaction film can be made the anodised electrolyte of silicon, for example carry out anodic oxidation in the SPA and (for example, can open flat 3-6826 communique (putting down into 3 years (1991) January 14 openly) with reference to spy as Japan's publication communique, the spy opens clear 52-78374 communique (disclose clear and 52 years (1977) July 1), the spy opens 2003-133309 communique (putting down into 15 years (2003) Mays 9 openly); 497～506 pages of No. the 5th, Applied Physics the 44th volumes 1975,124～125 pages of the towering works in electronic technology pandect MOS device (first edition in 1973) moral mountain).

In anodic oxidation, make silicon ion move to the surface of silicon substrate by applying voltage, on the silicon substrate surface, form silicon dioxide film.In addition, after forming silicon dioxide film, generate silicon ion from silicon substrate, purpose is to carry out oxidation reaction on the interface of formed silicon dioxide film and electrolyte (surface of silicon dioxide film).And then, in order to make this silicon ion pass the interface (surface of silicon dioxide film) that silicon dioxide film arrives silicon dioxide film and electrolyte, need apply the above big voltage (124～125 pages of the towering works in electronic technology pandect MOS device (first edition in 1973) moral mountain) of 100V usually.

On the other hand, author of the present invention has proposed a kind of chemical formula oxide-film formation method that forms oxide-film with chemical mode, rather than the electric chemical formula oxide-film formation method of utilizing voltage to apply (for example, can be opened 2004-47935 communique (putting down into 16 years (2004) February 12 openly) with reference to the spy as Japan's publication communique, Te Kaiping 9-45679 communique (putting down into 9 years (1997) February 14 openly), the spy opens 2002-57154 communique (putting down into 14 years (2002) February 22 openly), the spy opens 2002-64093 communique (putting down into 14 years (2002) February 28 openly); J.Applied Physics Letters, 81,18, pp3410-3412 (2002) and J.Applied Physics Letters, 94,11, pp7328-7335 (2003)).For example, above-mentioned spy opens and has proposed a kind of method in the 2004-47935 communique, its thin oxide film about strong oxidizing property soup formation 1nm such as use red fuming nitric acid (RFNA) on the surface of semiconductor substrates such as silicon.

Yet, in the manufacturing of the LCD of flexibility, need make TFT and possess the device slimming of TFT.For this reason, also require to form high-quality uniform grid oxidation film, thereby both kept insulating properties, accomplish filming again.

And then, in the manufacturing of the LCD of flexibility, PETG) etc. need be at PET (Polyethyleneterephthalate: form TFT on the organic substance substrate.For this reason, must under smaller or equal to 200 ℃ low temperature, form TFT.

But, need under the condition more than 800 ℃, more than 400 ℃, to form grid oxidation film respectively in above-mentioned high-temperature oxidation and the CVD method.Therefore, be unsuitable for forming TFT in the manufacturing of flexible LCD.In addition, in the high-temperature thermal oxidation method, also exist heat to cause diffuse dopants, the ruined problem of shallow bonding.

And then the CVD method is the method for deposited oxide film on substrate, therefore, can't form uniform grid oxidation film on the substrate with concavo-convex or curved surface.In addition, compare its membranous variation with the formed oxide-film of direct oxidation method that uses thermal oxidation solution etc.Therefore, can't form and possess the high reliability grid oxidation film of insulating properties completely.In addition, as mentioned above, the thickness that grid oxidation film must possess certain degree is destroyed to prevent to insulate, and this can cause the inhomogeneous of grid oxidation film.

In addition, the CVD method must be used much such as SiH ₄Deng being rejected to possible hazardous gas on fire in the atmosphere, necessary careful during use.Therefore,, import up to emission treatment, need a large amount of equipment from gas in order to carry out the CVD method.Therefore, people's expectation can form high-quality grid oxidation film simply and easily.

Therefore, if can be formed uniformly high-quality grid oxidation film, just can realize than existing thinner grid oxidation film.

In addition, in existing anode oxidation method,, need high voltage (being generally more than the 100V) for the silicon ion that makes silicon substrate moves to grid oxidation film (silicon dioxide film) from silicon substrate.Particularly, in anode oxidation method, the growth of the silicon dioxide film (oxide-film) on the silicon substrate surface in the electrolyte is by making the silicon ion (Si of silicon substrate ⁺) pass from the interface of silicon substrate-silicon dioxide film silicon dioxide film to silicon dioxide film surface (silicon dioxide film-electrolyte interface) thus move on the silicon dioxide film surface and produce oxidation reaction.Therefore, along with the formation of silicon dioxide film and the increase of thickness, need to increase the voltage that is applied on the silicon substrate.But voltage is crossed conference and is destroyed insulation, therefore, is difficult to form thicker and silicon dioxide film high-quality.

In addition, in anode oxidation method, the ion in the electrolyte can be sneaked in the oxide-film, is difficult to form high-quality oxide-film.Therefore, for example the stability of electrical characteristic is also insufficient.Therefore, make the oxide-film that utilizes anode oxidation method to form keep desired quality, must increase the thickness of oxide-film.Therefore, use anode oxidation method can not form high-quality oxide-film.Stress in the volumetric expansion of oxide-film is applied under the such shape of Si substrate, and sometimes stress can delay the growth of oxide-film.Consequently, the local attenuation of oxide-film of the part concentrated of stress.Therefore, can not form uniform oxide-film, leakage current appears in membranous variation.

Yet the driving of LCD is with having used CG silicon (Continuous Grain Silicon: TFT discontinuous crystal grain border silicon metal) among switch element or the peripheral driver LSI.CG silicon forms by thermal annealing, and crystallization this moment is collided mutually, can form angular protrusions.Therefore, the surface of CG silicon has complicated concaveconvex shape.Therefore, this complex surface need be formed the technology of even oxide-film.

In addition, the low temperature meeting in the manufacture process causes reliability decrease in general.For example, in the widely used TEOS oxidation (CVD method), be accompanied by low temperatureization in oxide-film forms, leakage current appears in membranous remarkable deterioration.That is, if reduce temperature, the membranous of oxide-film will further worsen.In addition, as described above, be difficult to make complex surfaces to form uniform oxide-film.

So, in the exploitation of the LCD of flexibility etc., how to reduce because make the properties of oxide-film that the low temperatureization of temperature causes, the decline of reliability just becomes maximum problem.

On the other hand, semiconductor device, especially use among the semiconductor integrated circuit etc. of MOS transistor, be accompanied by high integration, densification and the miniaturization of the electric circuit element that occurs makes the performance of use therein dielectric film improve particularly important.

In this semiconductor integrated circuit, the gate insulating film of MOS transistor normally utilizes in oxidizing gas such as dry oxygen or steam and carries out heat treated, is that so-called high-temperature thermal oxidation method forms with the high temperature more than 800 ℃.

Except the high-temperature thermal oxidation method, it is also known for organosilan, for example tetraethoxysilane (TEOS) etc. with after the hundreds of ℃ of thermal decompositions the chemical vapor deposition (CVD) method of deposited oxide film on the substrate, with the sputter evaporation form oxide the sputter vapour deposition method, in plasma, make the oxide-film formation methods such as plasma oxidation method of substrate surface oxidation.

In addition, known method also has by anodic oxidation makes the anode oxidation method that forms oxide-film after the substrate surface oxidation, for example, in hydrofluoric acid aqueous solution (electrolyte), apply voltage to silicon substrate, after forming porous matter anode reaction silicon fiml, this porous matter anode reaction film is carried out anodic oxidation (the publication communique spy of Japan opens flat 3-6826 communique (open day: put down on January 14th, 3 (1991))) in can making the anodised electrolyte of silicon, for example SPA.

On the other hand, author of the present invention has proposed to use the method (the publication communique spy of Japan opens 2002-64093 communique (open day: put down on February 28th, 14 (2002))) of oxidizability soup formation thin oxide films such as red fuming nitric acid (RFNA) on the surface of semiconductor substrates such as silicon.

For example, after silicon face is removed natural oxide film, promptly allowing to form thickness is nanometer (nm) or the following oxide-film as thin as a wafer of nanometer, also being difficult to reach can be used as the required quality of the dielectric film of semiconductor device, particularly be difficult to obtain the little dielectric film of leakage current density, among gate insulating film of thin-film transistor (TFT) etc., in order to keep withstand voltage, need to form several nanometers (nm) or thicker oxide-film.

In addition, in LCD etc., use the substrate of flexible substrate, for example PETG (PET) etc., when on this substrate, forming thin-film transistor (TFT), the temperature of this substrate is remained on below 200 ℃, in such low temperature manufacturing process, the gate insulating film etc. that also require to form TFT can be applied to the high-quality dielectric film of semiconductor device.

Summary of the invention

The present invention be directed to the problems referred to above and make, its purpose is to provide to be possessed particularly in the method for manufacturing thin film transistor of the gate insulating film of excellent quality aspect the characteristics such as insulation tolerance and utilizes method.In addition, the object of the present invention is to provide and also can form method of manufacturing thin film transistor oxide-film, under the low temperature on the organic substance substrates such as PET and utilize method.

In addition, another object of the present invention is to provide a kind of formation method of oxide-film, use the manufacture method of semiconductor device of this oxide-film and the manufacturing installation of this semiconductor device, the formation method of this oxide-film forms on semi-conductive surface when forming on the substrates such as above-mentioned PET under the situation of thin-film transistor (TFT) control thickness the time at low temperatures, perhaps when forming MOS transistor or use the large scale integrated circuit (LSI) etc. of MOS transistor, can be used for this gate insulating film, the high-quality oxide-film that possesses performances such as low-leakage current density feature.

Method of manufacturing thin film transistor of the present invention (this manufacture method) is a kind of method of manufacturing thin film transistor that possesses oxide-film, it is characterized in that, have: oxide-film forms operation, the substrate that the surface will be formed chemical oxide film is impregnated in the oxidizing solution that contains active oxidation kind (species), make the aforesaid substrate direct oxidation, form chemical oxide film thus.

In addition, this manufacture method is characterised in that above-mentioned oxide-film forms operation and forms above-mentioned active oxidation kind by the heating of oxidizing solution or the electrolysis of oxidizing solution.

In addition, this manufacture method is characterised in that, forms operation at above-mentioned oxide-film, aforesaid substrate is impregnated in the different above-mentioned oxidizing solution of concentration, and makes the concentration of above-mentioned oxidizing solution become high concentration oxygen voltinism solution from low concentration oxygen voltinism solution.

In addition, this manufacture method is characterised in that the concentration of above-mentioned low concentration oxidizing solution is lower than azeotropic concentration, and the concentration of above-mentioned high concentration oxidizing solution is azeotropic concentration.

In addition, this manufacture method is characterised in that, above-mentioned oxide-film form operation with above-mentioned low concentration oxygen voltinism solution concentration after as above-mentioned high concentration oxidizing solution.

In addition, this manufacture method is characterised in that, forms in the operation at above-mentioned oxide-film, and above-mentioned low concentration oxidizing solution heating back is used as above-mentioned high concentration oxidizing solution.

In addition, this manufacture method is characterised in that, above-mentioned oxide-film forms operation and undertaken by apply voltage on the above-mentioned substrate that will form oxide-film, makes oxide growth on the aforesaid substrate surface thus.

In addition, this manufacture method is characterised in that, the above-mentioned substrate that will form oxide-film possesses on the surface and is selected from least a in monocrystalline silicon, polysilicon, amorphous silicon, discontinuous crystal grain border silicon metal, carborundum and the SiGe.

In addition, this manufacture method is characterised in that above-mentioned oxidizing solution comprises: be selected from nitric acid, cross chloric acid, at least a solution, its gas or their mixed solution in the group of mixed solution, chloroazotic acid and the boiling water of mixed solution, sulfuric acid and the nitric acid of mixed solution, ammoniacal liquor and the hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide.

In addition, this manufacture method is characterised in that above-mentioned oxidizing solution is an azeotropic mixture.

In addition, this manufacture method is characterised in that above-mentioned oxidizing solution comprises: be selected from as with the azeotropic nitric acid (azeotropic concentration 68%) of the azeotropic mixture of water, as with the azeotropic sulfuric acid of the azeotropic mixture of water and as crossing at least a solution in the group of chloric acid (azeotropic concentration 71%) with the azeotropic of the azeotropic mixture of water.

In addition, this manufacture method is characterised in that above-mentioned oxide-film forms operation and carries out under the temperature below 200 ℃.

In addition, this manufacture method is characterised in that to have: the operation that further forms dielectric film after forming above-mentioned chemical oxide film on this chemical oxide film.

In addition, this manufacture method is characterised in that above-mentioned oxide-film forms operation and comprises following operation: substrate is impregnated in the oxidizing solution that is lower than azeotropic concentration, forms the 1st oxide-film thus; And under the state in substrate being impregnated into the above-mentioned oxidizing solution that is lower than azeotropic concentration, the above-mentioned oxidizing solution that is lower than azeotropic concentration is concentrated into azeotropic concentration (keeping azeotropic concentration after being heated to the azeotropic state), on the 1st oxide-film, forms the 2nd oxide-film thus.

In addition, this manufacture method is characterised in that the above-mentioned substrate that will form chemical oxide film possesses carborundum on the surface.In this case, the substrate that form chemical oxide film also can be a carborundum.

In addition, this manufacture method is characterised in that above-mentioned oxidizing solution is a nitric acid.

In addition, this manufacture method is characterised in that, comprises the operation of above-mentioned chemical oxide film being carried out nitrogen treatment after above-mentioned oxide-film forms operation.

By means of above-mentioned each structure, the substrate that form oxide-film is impregnated in the oxidizing solution that contains the active oxidation kind.Because the oxidizing force of active oxidation kind is very strong, to form the zone of chemical oxide film by the direct oxidation of active oxidation kind so be impregnated on the substrate in this solution.Thus, formed chemical oxide film in this zone.According to this kind mode, in said structure, substrate is impregnated into and forms chemical oxide film in the oxidizing solution.Therefore, even substrate surface has concavo-convex or curved surface, oxidizing solution also can spread all over substrate surface equably.Thus, spreading all over the chemical oxide film that can both form uniform film thickness on the whole zone that will form chemical oxide film.

And then in said structure, chemical oxide film should form the orientation substrate growth of chemical oxide film.Therefore, the interface of chemical oxide film and substrate is changing always, forms chemical oxide film simultaneously, can make this interface cleaning thus.

Thus, just can produce possess high reliability, the high performance thin-film transistor of high-quality chemical oxide film.

In thin-film transistor, grid oxidation film membranous born the electrical characteristic that determines thin-film transistor and the important function of reliability.That is, in thin-film transistor, require to possess the performance (reliability, characteristic) that the grid oxidation film of insulating properties completely can directly have influence on the various devices that possess TFT, therefore, it possesses high-quality, high reliability special requirement.Therefore, utilize above-mentioned oxide-film to form operation and form grid oxidation film, just can form the high reliability of excellent such as insulation tolerance, high-quality grid oxidation film.Therefore, can realize the filming of grid oxidation film.In addition, follow the slimming that also can realize thin-film transistor therewith.

And then, in said structure, utilize the oxidizing solution of the active oxidation kind that contains strong oxidizing force to form chemical oxide film, therefore, for example also can form chemical oxide film under the temperature conditions below 200 ℃.Therefore, can produce and also be applicable to the thin-film transistor of making LCD with flexible base, board (for example plastics, PETG (PET)).Thus, for example also can produce the plastic film transistor that hangs down threshold value on the plastic base.

Thin-film transistor of the present invention is to utilize above-mentioned any one method for fabricating thin film transistor manufactured thin film transistor, it is characterized in that possessing: utilize oxidizing solution to carry out oxidation and the chemical oxide film that forms.Thus, because it possesses high-quality oxide-film (particularly grid oxidation film), therefore become high performance thin-film transistor.

In addition, thin-film transistor of the present invention is characterised in that it is the high film of atomic density that above-mentioned chemical oxide film becomes near substrate one side.

In addition, thin-film transistor of the present invention is characterised in that above-mentioned chemical oxide film is a grid oxidation film.

Display unit of the present invention (this display unit) is characterised in that to possess above-mentioned thin-film transistor.Thus, for example, can improve the switching characteristic of display unit by thin-film transistor is used as switch element.

And then, in this display unit, preferably possess and be used for the drive circuit of driving switch element, above-mentioned thin-film transistor as the thin-film transistor that constitutes this drive circuit, and is formed these switch elements and thin-film transistor simultaneously.

The transistor that is used for constituting drive circuit also can use above-mentioned thin-film transistor to constitute, and can cut down the manufacturing process of display unit thus.

In addition, display unit array display device preferably.In addition, so-called " display unit " refers to and is used for the various displays such as LCD, OLED display, flat-panel monitor of display image.

In addition, method of modifying as the oxide-film of the present invention that utilizes one of method of this manufacture method is characterised in that, oxide-film to membrane thickness unevenness carries out above-mentioned any one oxide-film formation operation, membranous (the making the thickness of the oxide-film of membrane thickness unevenness become even) of improving above-mentioned oxide-film thus.

The method of modifying of above-mentioned oxide-film also can be membranous uneven oxide-film to be carried out above-mentioned any described oxide-film form operation, membranous (the making the membranous of membranous uneven oxide-film become even) of improving above-mentioned oxide-film thus.

By means of above-mentioned each structure, utilize the oxide-film formation operation in this manufacture method that the uneven oxide-film of thickness (or membranous) is handled.Thus, utilize the solution that contains the active oxidation kind that uneven oxide-film is carried out oxidation, just can form uniform chemical oxide film.Therefore, can form high reliability, high-quality chemical oxide film.

In addition, the method for modifying of this oxide-film is preferably at using the formed oxide-film of for example existing method (particularly CVD method) to carry out.In addition, the CVD method forms oxide-film by deposition, therefore, and the thickness of formed oxide-film and membranous inhomogeneous.Therefore, at this uneven oxide-film,, just can make it become uniform chemical oxide film by carrying out the processing that oxide-film forms operation.Thus, various characteristicses such as increase be can improve, the high reliability of these characteristic aspect excellences, high-quality chemical oxide film can be formed in because of thickness and membranous inhomogeneous insulation breakdown that causes and leakage current density.

For example, CG silicon forms by thermal annealing, and crystallization this moment is collided mutually, can form angular protrusions.Therefore, the surface of CG silicon has complicated concaveconvex shape.Therefore, implement above-mentioned oxide-film method of modifying, just can form thickness and membranous uniform oxide-film at complex surface with this concaveconvex shape (projection).

In addition, carry out preliminary treatment (pre-oxidation) before stating the oxide-film method of modifying on the implementation, after the modification of having implemented oxide-film, form operation (oxide-film well-known or of the present invention forms operation) by implementing common oxide-film, just can the thickness that improves chemical oxide film and membranous in formation high reliability, high-quality chemical oxide film.

In addition, for containing for example uneven layer of impurity such as carbon,, can form uniform chemical oxide film by carrying out said method.

The formation method of oxide-film of the present invention (this formation method) is in order to solve above-mentioned problem, it is characterized in that, has following operation: make the oxidizing solution or its gas contact semiconductor that are lower than azeotropic concentration, on above-mentioned semiconductor surface, form the 1st chemical oxide film thus; And make than the oxidizing solution of the oxidizing solution of azeotropic concentration or its gas high concentration or the semiconductor of its gas contact formation the 1st chemical oxide film, form the 2nd chemical oxide film thus.

In addition, this formation method also can be described as a kind of to have the method that following operation is a feature: make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, form the 1st chemical oxide film thus on above-mentioned semiconductor surface; And the oxidizing solution or its gas generation effect that make high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film thus.

In addition, so-called " on the 1st chemical oxide film form the 2nd chemical oxide film " is not the stepped construction of the 1st chemical oxide film and the 2nd chemical oxide film, and is meant and forms identical, as to be atomic density distribution membrane structure.

In addition, in this formation method, the thickness of the 2nd chemical oxide film can be formed than the 1st chemical oxidation thickness.

In addition, in this formation method, the operation that is preferably formed above-mentioned the 1st chemical oxide film and the 2nd chemical oxide film is above-mentioned semiconductor is impregnated in the above-mentioned oxidizing solution and carries out.

In addition, in this formation method, preferred above-mentioned semiconductor is selected from least a among monocrystalline silicon, polysilicon, amorphous silicon, carborundum and the SiGe, and above-mentioned the 1st chemical oxide film and the 2nd chemical oxide film are silicon oxide layers.

In addition, in this formation method, the oxidizing solution of above-mentioned high concentration or its gas is oxidizing solution or its gas of azeotropic concentration preferably.

In addition, in this formation method, above-mentioned oxidizing solution or its gas preferably comprise: be selected from nitric acid, cross chloric acid, at least a solution, its gas or their mixture in the group of mixed solution, chloroazotic acid and the boiling water of mixed solution, sulfuric acid and the nitric acid of mixed solution, ammoniacal liquor and the hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide.

In addition, in this formation method, the oxidizing solution of preferred above-mentioned low concentration or its gas is at least a of aqueous solution of nitric acid, aqueous sulfuric acid and the group of crossing the chloric acid aqueous solution and is selected from solution or its gas that concentration is lower than azeotropic concentration, and the oxidizing solution of above-mentioned high concentration or its gas are at least a in the above-mentioned aqueous solution group and solution or its gas that is selected from azeotropic concentration.

In addition, in this formation method, preferably comprise: the operation of after above-mentioned semi-conductive surface forms chemical oxide film, above-mentioned chemical oxide film being carried out nitrogen treatment.

The manufacture method (this manufacture method) of semiconductor device of the present invention is characterized in that having the oxide-film that utilizes above-mentioned any described oxide-film formation method to form chemical oxide film and form operation in order to solve above-mentioned problem.

That is, for example, this manufacture method is characterised in that to possess following operation: make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, form the 1st chemical oxide film on above-mentioned semiconductor surface; And the oxidizing solution or its gas generation effect that make high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

In addition, in this manufacture method, preferably from being selected from nitric acid, crossing chloric acid, select in the group of the mixture of at least a and water the sulfuric acid and selecting in the concentration range lower than azeotropic concentration, the high concentration above the set point of the concentration range of above-mentioned low concentration is selected and be chosen to be to the oxidizing solution of above-mentioned high concentration or its gas from the group of said mixture for the oxidizing solution of above-mentioned low concentration or its gas.

In addition, in this manufacture method, preferably the oxidizing solution of above-mentioned high concentration or its gas comprise: be selected from as with the azeotropic nitric acid of the azeotropic mixture of water, as with the azeotropic sulfuric acid of the azeotropic mixture of water and as crossing at least a solution or its gas in the chloric acid with the azeotropic of the azeotropic mixture of water.

In addition, in this manufacture method, above-mentioned semiconductor preferably comprises: be selected from least a among monocrystalline silicon, polysilicon, amorphous silicon, carborundum and the SiGe.

In addition, in this manufacture method, preferably comprise: the operation of after above-mentioned semi-conductive surface forms chemical oxide film, above-mentioned chemical oxide film being carried out nitrogen treatment.

In addition, in this manufacture method, preferably has following operation: after above-mentioned semi-conductive surface forms chemical oxide film or after above-mentioned chemical oxide film is carried out nitrogen treatment, form at least a coverlay of oxide-film, silicon nitride film, high dielectric film (high dielectric film) and the ferroelectric thin film (ferroelectric film) made by chemical vapor deposition (CVD).

Semiconductor device of the present invention utilizes the manufacture method of above-mentioned any semiconductor device and obtains, and it is characterized in that possessing: utilize the chemical oxide film of above-mentioned oxidizing solution with semiconductor oxide.

The manufacturing installation of semiconductor device of the present invention is characterized in that possessing following function in order to solve above-mentioned problem: make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, form the 1st chemical oxide film at above-mentioned semiconductor surface; And the oxidizing solution or its gas generation effect that make high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

Promptly, this manufacturing installation is a kind of manufacturing installation with semiconductor device of the oxide-film formation portion that is used on semiconductor surface forming chemical oxide film, it is characterized in that having following function: above-mentioned oxide-film formation portion utilizes the formation method (this formation method) of above-mentioned any described oxide-film or the manufacture method (this manufacture method) of above-mentioned any described semiconductor device to form chemical oxide film at semiconductor surface.

Above-mentioned each method and each structure be at the oxidizing solution that uses low concentration (preferably being lower than azeotropic concentration) or its gas after semiconductor surface forms the 1st chemical oxide film, use the oxidizing solution of higher concentration (preferably azeotropic concentration) or its gas further to form the 2nd chemical oxide film.The density of the 1st chemical oxide film is low, and by its performance oxidation catalyst effect, the result just can form the 2nd chemical oxide film.By using high concentration oxidizing solution or gas to carry out oxidation, can increase the density of oxide-film.Thus, just can become the high-quality oxide-film that keeps performances such as low-leakage current density feature by final the 1st chemical oxide film that forms and oxide-film that the 2nd chemical oxide film constituted.In addition, also can form oxide-film down at low temperature (for example below 200 ℃).And then, by the oxidizing solution of adjusting high concentration or the concentration of its gas, can make the control of the thickness of the 2nd chemical oxide film become easy.

According to this kind mode, form the 1st chemical oxide film and the 2nd chemical oxide film stage by stage, and, make the 1st chemical oxide film keep low atomic density, make the 2nd chemical oxide film possess the thickness thicker, thereby can on semiconductor surface, be formed uniformly the high-quality chemical oxide film of expection thickness at low temperatures than the 1st chemical oxide film.That is, can improve the membranous of chemical oxide film, form the high-quality chemical oxide film of low-leakage current density.In addition, also can provide the high performance semiconductor device that possesses this high-quality chemical oxide film.

As mentioned above, by means of oxide-film formation method of the present invention, form the 2nd chemical oxide film after on semiconductor, forming the 1st chemical oxide film, therefore, by possessing the oxidizing solution or its gas that make low concentration semiconductor surface is produced work in order to form the operation of the 1st chemical oxide film at above-mentioned semiconductor surface and to make the oxidizing solution of high concentration or its gas produce the operation of doing in order to formation the 2nd chemical oxide film on above-mentioned the 1st chemical oxide film, just can at low temperatures high-quality above-mentioned chemical oxide film be formed the coverlay of expection thickness.

Manufacture method by means of semiconductor device of the present invention, form the 2nd chemical oxide film after on semiconductor, forming the 1st chemical oxide film, therefore, by possessing the oxidizing solution or its gas that make low concentration semiconductor surface is produced work in order to form the operation of the 1st chemical oxide film at above-mentioned semiconductor surface and to make the oxidizing solution of high concentration or its gas produce the operation of doing in order to formation the 2nd chemical oxide film on above-mentioned the 1st chemical oxide film, just can produce the semiconductor device of coverlay with the expection thickness that comprises above-mentioned the 1st chemical oxide film.

Manufacturing installation by means of semiconductor device of the present invention, form the 2nd chemical oxide film after on semiconductor, forming the 1st chemical oxide film, therefore, by possessing the oxidizing solution or its gas that make low concentration semiconductor surface is produced work in order to form the function of the 1st chemical oxide film at above-mentioned semiconductor surface, and make the oxidizing solution of high concentration or its gas produce the function of doing in order to formation the 2nd chemical oxide film on above-mentioned the 1st chemical oxide film, just can produce high-performance and stable semiconductor device comprising the dielectric film that forms the coverlay of the expection thickness that comprises above-mentioned the 1st chemical oxide film on the above-mentioned semi-conductive matrix.

In addition, the present invention also can be expressed as.

[1] the formation method of oxide-film of the present invention is characterised in that to possess following operation: make the oxidizing solution of low concentration or its gas (oxidizing gas) to semiconductor surface generation effect, form the 1st chemical oxide film on above-mentioned semiconductor surface; And the oxidizing solution or its gas generation effect that make high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

[2] the formation method of oxide-film of the present invention is characterised in that, in the formation method of above-mentioned [1] described oxide-film, above-mentioned semiconductor is select among monocrystalline silicon, polysilicon, amorphous silicon, carborundum and SiGe at least a, and the main body of above-mentioned chemical oxide film is made of the oxide-film of silicon.

[3] the formation method of oxide-film of the present invention is characterised in that, in the formation method of above-mentioned [1] described oxide-film, the oxidizing solution of above-mentioned low concentration or its gas are that at least a of aqueous solution of nitric acid, aqueous sulfuric acid and the group of crossing the chloric acid aqueous solution and be lower than the solution of azeotropic concentration or its gas from concentration selected, and the oxidizing solution of above-mentioned high concentration or its gas are at least a in the above-mentioned aqueous solution group and select from the solution of azeotropic concentration or its gas.

[4] the formation method of oxide-film of the present invention is characterised in that, in the formation method of any described oxide-film of above-mentioned [1]～[4], be included in and form the operation of above-mentioned chemical oxide film being carried out after the chemical oxide film nitrogen treatment on the above-mentioned semi-conductive surface.

[5] manufacture method of semiconductor device of the present invention is characterised in that, possesses following operation: make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, form the 1st chemical oxide film at above-mentioned semiconductor surface; And the oxidizing solution or its gas generation effect that make high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

[6] manufacture method of semiconductor device of the present invention is characterised in that, in the manufacture method of above-mentioned [5] described semiconductor device, the oxidizing solution of above-mentioned low concentration or its gas are selected from from nitric acid, cross in the group of mixture of at least a and water of selecting chloric acid, the sulfuric acid and select in the concentration range that concentration is lower than azeotropic concentration; The high concentration of the set point of the concentration range that surpasses above-mentioned low concentration is selected and be chosen to be to the oxidizing solution of above-mentioned high concentration or its gas from above-mentioned group.

[7] manufacture method of semiconductor device of the present invention is characterised in that, in the manufacture method of any described semiconductor device of above-mentioned [5] or [6], the oxidizing solution or the oxidizing gas of above-mentioned high concentration comprise: from as and the azeotropic nitric acid of the azeotropic mixture of water, as with the azeotropic sulfuric acid of the azeotropic mixture of water and as crossing at least a solution or its gas of selecting the chloric acid with the azeotropic of the azeotropic mixture of water.

[8] manufacture method of semiconductor device of the present invention is characterised in that, in the manufacture method of any described semiconductor device of above-mentioned [5]～[7], above-mentioned semiconductor comprises: that selects among monocrystalline silicon, polysilicon, amorphous silicon, carborundum and the SiGe is at least a.

[9] manufacture method of semiconductor device of the present invention is characterised in that, in the manufacture method of any described semiconductor device of above-mentioned [5]～[8], comprise: the operation of after above-mentioned semi-conductive surface forms chemical oxide film, above-mentioned chemical oxide film being carried out nitrogen treatment.

[10] manufacture method of semiconductor device of the present invention is characterised in that, in the manufacture method of any described semiconductor device of above-mentioned [5]～[9], have: the operation of at least a coverlay of formation is made by chemical vapor deposition (CVD) after above-mentioned semi-conductive surface forms chemical oxide film or after above-mentioned chemical oxide film is carried out nitrogen treatment oxide-film, silicon nitride film, high dielectric film and ferroelectric thin film.

[11] manufacturing installation of semiconductor device of the present invention is characterised in that to possess following function: make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, form the 1st chemical oxide film at above-mentioned semiconductor surface; And the oxidizing solution or its gas generation effect that make high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

Formation method by means of the oxide-film of the invention described above, semiconductor surface is produced do by possessing the oxidizing solution that makes low concentration or its gas in order to form the operation of the 1st chemical oxide film on the above-mentioned semiconductor surface and to make the oxidizing solution of high concentration or its gas produces and does to expect the coverlay of thickness in order to form the operation of the 2nd chemical oxide film on above-mentioned the 1st chemical oxide film, just can at low temperatures high-quality above-mentioned chemical oxide film be formed.

Manufacture method by means of the semiconductor device of the invention described above, by possessing the oxidizing solution or its gas that make low concentration semiconductor surface is produced work in order to form the operation of the 1st chemical oxide film at above-mentioned semiconductor surface and to make the oxidizing solution of high concentration or its gas produce the operation of doing in order to formation the 2nd chemical oxide film on above-mentioned the 1st chemical oxide film, just can produce the semiconductor device of coverlay with the expection thickness that comprises above-mentioned the 1st chemical oxide film.

Manufacturing installation by means of the semiconductor device of the invention described above, by possessing the oxidizing solution or its gas that make low concentration semiconductor surface is produced work in order to form the function of the 1st chemical oxide film at above-mentioned semiconductor surface and to make the oxidizing solution of high concentration or its gas produce the function of doing in order to formation the 2nd chemical oxide film on above-mentioned the 1st chemical oxide film, just can comprise the dielectric film that forms the coverlay of the expection thickness that comprises above-mentioned the 1st chemical oxide film on the above-mentioned semi-conductive matrix, can produce the semiconductor device of high-performance and stability of characteristics.

Further other purpose, feature and advantage of the present invention just can be clear fully by record shown below.In addition, the advantage of the present invention as can be known just of the following explanation by the reference accompanying drawing.

Description of drawings

Fig. 1 is the profile of the thin-film transistor of an embodiment of the invention.

Fig. 2 (a) is the profile of manufacturing process of the thin-film transistor of presentation graphs 1.

Fig. 2 (b) is the profile of manufacturing process of the thin-film transistor of presentation graphs 1.

Fig. 2 (c) is the profile of manufacturing process of the thin-film transistor of presentation graphs 1.

Fig. 2 (d) is the profile of manufacturing process of the thin-film transistor of presentation graphs 1.

Fig. 2 (e) is the profile of manufacturing process of the thin-film transistor of presentation graphs 1.

Fig. 2 (f) is the profile of manufacturing process of the thin-film transistor of presentation graphs 1.

Fig. 3 is that expression is passed through the oxidation of 2 stages and the transistorized electric capacity of manufactured thin film (C)-voltage (V) performance plot.

Fig. 4 is that expression is by the oxidation of 2 stages and grid oxidation film (SiO in the manufactured thin film transistor ₂Film) XPS spectral characteristic figure.

Fig. 5 is that expression has SiO ₂Film is as the I-V performance plot that creates the thin-film transistor of grid oxidation film by the oxidation of 2 stages.

Fig. 6 is that expression is passed through the oxidation of 2 stages and the transistorized C-V performance plot of manufactured thin film.

Fig. 7 is that expression is passed through the oxidation of 2 stages and the transistorized C-V performance plot of manufactured thin film.

Fig. 8 is that expression is by the oxidation of 2 stages and grid oxidation film (SiO in the manufactured thin film transistor ₂Film) growth thickness-time response figure.

Fig. 9 is the summary section of the major part of the manufacturing installation that uses in the 2 stage oxidizing process of expression.

Figure 10 is the summary section that voltage applies the major part structure of employed manufacturing installation in the method in expression an embodiment of the invention.

Figure 11 is that expression utilizes voltage to apply the chart of electric capacity (C) and the relation of voltage (V) in the thin-film transistor that manufactured comes out.

Figure 12 is that expression utilizes voltage to apply grid oxidation film (SiO in the thin-film transistor that manufactured comes out ₂Film) the growth thickness and the chart of time relation.

Figure 13 is that expression utilizes voltage to apply the chart of the relation of electric current and voltage in the thin-film transistor that manufactured comes out.

Figure 14 is that expression utilizes voltage to apply leakage current density and SiO in the thin-film transistor that manufactured comes out ₂The chart of the dependency relation of thickness.

Figure 15 is that expression utilizes voltage to apply the chart of the relation of the relation of electric current and voltage in the thin-film transistor that manufactured comes out and electric capacity and voltage.

Figure 16 is expression with the chart of grid oxidation film in the thin-film transistor of Figure 15 with the relation of electric current under 200 ℃ of situations of carrying out forming after the heat treated electrode and voltage.

Figure 17 is the chart of the relation of electric capacity and voltage in the thin-film transistor of expression Figure 16.

Figure 18 is expression with the grid oxidation film of the thin-film transistor of Figure 15 chart with the relation of electric capacity under 600 ℃ of situations of carrying out forming after the heat treated electrode and voltage.

Figure 19 is the chart of the relation of electric current and voltage in the thin-film transistor of expression Figure 18.

Figure 20 is the profile of another thin-film transistor of an embodiment of the invention.

Figure 21 is the summary section of the major part of the manufacturing installation that uses in the embodiments of the present invention of expression.

Figure 22 (a) is the mos capacitance device manufacturing process flow process profile in the embodiments of the present invention.

Figure 22 (b) is the mos capacitance device manufacturing process flow process profile in the embodiments of the present invention.

Figure 22 (c) is the mos capacitance device manufacturing process flow process profile in the embodiments of the present invention.

Figure 22 (d) is the mos capacitance device manufacturing process flow process profile in the embodiments of the present invention.

Figure 22 (e) is the mos capacitance device manufacturing process flow process profile in the embodiments of the present invention.

Figure 22 (f) is the mos capacitance device manufacturing process flow process profile in the embodiments of the present invention.

Figure 23 is electric capacity (C)-voltage (V) performance plot of mos capacitance device obtained in the embodiments of the present invention.

Figure 24 is SiO ₂The XPS spectral characteristic figure of film.

Figure 25 possesses SiO ₂I-V performance plot in the MOS structure diode of film.

Figure 26 is the C-V performance plot in the MOS structure diode.

Figure 27 is the C-V performance plot in the MOS structure diode.

Figure 28 is SiO ₂Growth thickness-time response the figure of film.

Figure 29 is that expression is by grid oxidation film (SiO in the continuous oxidation manufactured thin film transistor ₂The chart of oxidization time film) and the relation of thickness.

Figure 30 is expression grid oxidation film (SiO by continuous oxidation or discontinuous oxidation and in the manufactured thin film transistor ₂Film) XPS spectral characteristic figure.

Embodiment

Below, describe the present invention with reference to accompanying drawing in detail by execution mode.

[the 1st execution mode]

According to Fig. 1～Figure 20 embodiments of the present invention are described below.But the present invention is not limited to this.

Be that example illustrates embodiments of the present invention with the thin-film transistor (TFT) that is applied to flexible liquid crystal display or IC etc. below.Method of manufacturing thin film transistor of the present invention (this manufacture method) is that a kind of substrate that will form grid oxidation film (chemical oxide film) is impregnated into and makes this substrate surface direct oxidation in the solution that contains the active oxidation kind, is formed uniformly the method for high-quality oxide-film thus.

At first, problem points when manufacturing is applied to the TFT of flexible liquid crystal display or IC etc. is described.

In order to make flexible LCD etc., need on organic substance substrates such as PET, form TFT.The fusing point of this organic substance substrate is lower, is up to 200 ℃.Therefore, in order to make flexible LCD, must under the low temperature below 200 ℃, form TFT.

In TFT, grid oxidation film is the important oxide-film that influences the performance of the various devices that possess TFT.At present, grid oxidation film utilizes CVD method deposition and forms.In addition, also need to realize the low temperatureization of CVD method.Current, the CVD method that temperature is minimum is the method for adding ozone in tetraethoxysilane (TEOS).Utilize this method, can under 300 ℃～400 ℃ temperature, form oxide-film.Therefore, use the CVD method under the low temperature below 200 ℃, not form TFT.

In addition, on the gate electrode of TFT, applied higher voltage.Therefore, grid oxidation film requires to possess insulating properties completely.The substrate surface that forms grid oxidation film has formed various fine patterns, has concavo-convex (unevenness).As described above, the CVD method forms grid oxidation film by deposition.Therefore, utilize the CVD method having formation grid oxidation film on the substrate of concaveconvex shape, difference can appear in the sedimentation state of oxide-film.Consequently, formed grid oxidation film becomes inhomogeneous.Therefore, formed grid oxidation film can not guarantee insulating properties completely, and leakage current density increases.That is, use the quality and the poor reliability of the formed grid oxidation film of CVD method.

Therefore, use the grid oxidation film of the TFT of existing C VD method generation to guarantee insulating properties completely, need possess thickness to a certain degree in order insulation breakdown ground not occur.When the LCD of flexibilities such as Production Example such as sheet LCD, require to realize the filming of TFT certainly.For this reason, must carry out the filming of grid oxidation film.

Yet,, just can not guarantee insulating properties completely if utilize the formed grid oxidation film of CVD method to do thinlyyer than present situation.Therefore, utilize further filming of the formed grid oxidation film of CVD method.

So, utilize the CVD method not only can not form high-quality grid oxidation film, nor can under the low temperature below 200 ℃, form grid oxidation film.

Therefore, in order to make flexible LCD etc., grid oxidation film form operation low temperatureization, homogenizing, high-qualityly just become particularly important.

In order to make this TFT, the substrate that method of manufacturing thin film transistor of the present invention (this manufacture method) will form grid oxidation film (chemical oxide film) is impregnated into and makes this substrate direct oxidation in the oxidizing solution that contains the active oxidation kind, thus, even under the low temperature below 200 ℃, also can be formed uniformly high-quality oxide-film.That is, thin-film transistor of the present invention is the high performance thin-film transistor that possesses high-quality oxide-film.

Secondly, the structure of TFT of the present invention is described.

As shown in Figure 1, the thin-film transistor 1 of present embodiment is staggered structure: the semiconductor layer 5 that forms source electrode 6, drain electrode 7 and be connected with them on processed substrate 2 forms grid 3 thereon across grid oxidation film 4.In addition, thin-film transistor 1 is being used under the situation of display unit for example, and the grid 3 that is connected to drain electrode 7 is formed on the grid oxidation film 4.And then, the diaphragm 9 that has formed semiconductor layer 5, source electrode 6 in this thin-film transistor 1 and covered.

In thin-film transistor 1, electric current flows between source electrode 6, drain electrode 7 via semiconductor layer 5.Therefore, semiconductor layer 5 is very important with the interface maintenance cleaning of grid oxidation film 4.

In thin-film transistor 1, it is characterized in that grid oxidation film 4 is film formed by the chemical oxidation that semiconductor layer 5 direct oxidations are formed.Shown in the manufacturing example for example described later, grid oxidation film 4 is to form chemical oxide film on semiconductor layer 5 directions, therefore, and the cleaning always of the interface of semiconductor layer 5 and grid oxidation film 4.In addition, grid oxidation film 4 irrespectively evenly forms with the surface state of semiconductor layer 5, therefore, has high reliability, high-quality.

Grid oxidation film 4 comprises the 1st oxide-film (the 1st chemical oxide film) 4a and the 2nd oxide-film (the 2nd chemical oxide film).Formation about grid oxidation film 4 will be narrated in the back.Grid oxidation film 4 is the oxides after the material generation oxidation of semiconductor layer 5.That is, generally, the 1st oxide-film 4a is identical with the composition of the 2nd oxide-film 4b, can not distinguish each dielectric film.Here, for ease of explanation, it is divided into the 1st oxide-film 4a and the 2nd oxide-film 4b.Yet, as described later shown in, the 1st oxide-film 4a is to form in the different oxidizing solution of concentration with the 2nd oxide-film 4b, so its atomic density difference.So, grid oxidation film 4 just becomes and forms identical but be the structure that atomic density distributes.That is, grid oxidation film 4 comprises relative the 2nd high oxide-film 4b with atomic density of the 1st low relatively oxide-film 4a of atomic density.And, forming the 2nd high oxide-film 4b of atomic density near processed substrate 2 one sides.The 2nd oxide-film 4b is layered on the semiconductor layer 5, is formed with the interface with semiconductor layer 5.

The siliceous material of semiconductor layer 5 preferred monocrystalline silicon, polysilicon, amorphous silicon, discontinuous crystal grain border silicon metal, carborundum and SiGe etc.

Particularly, in using the multi-crystal TFT of polysilicon, can be on processed substrate 2 peripheral circuit such as integrated drive electronics as semiconductor layer 5.Therefore, semiconductor layer 5 preferably is made of polysilicon.

Here, use the manufacturing procedure picture explanation of Fig. 2 to have the manufacture method of the thin-film transistor 1 of said structure.In addition, be illustrated at the semiconductor layer 5 of thin-film transistor 1 manufacture method below for the multi-crystal TFT under the situation of polysilicon.In this manufacture method, having distinctive operation is the operation (oxide-film forms operation: Fig. 2 (c) (d)) that forms grid oxidation film 4.

At first, tin indium oxide) utilize sputtering method for example to form ITO (Indium TinOxide: film such as to processed substrate 2, on this ITO film, utilize photoetching and etching liquid (hydrochloric acid+nitric acid) to carry out wet etching, form source electrode 6, drain electrode 7 and pixel electrode 8 (Fig. 2 (a)) thus simultaneously.Processed substrate 2 has insulating properties and gets final product, even can use flexible base, boards such as plastics system substrate or non-flexible substrate also can use glass substrate, quartz, silicon substrate etc. in addition.

Then, utilize the CVD method to form polysilicon 51 as semi-conducting material (Fig. 2 (b)).In addition, when formed polysilicon 51 surfaces form natural oxide film, utilizing well-known RCA ablution, be after the ammoniacal liquor-hydrogen peroxide class aqueous solution cleans, is about 5 minutes of dipping in the dilute hydrofluoric acid solution of 0.5% (Capacity Ratio, below note is vol.) in concentration preferably.Thus, natural oxide film is removed fully, polysilicon surface becomes clean state.Like this, also can improve the membranous of follow-up chemical oxide film.

Then, be impregnated in the oxidizing solution having formed polysilicon processed substrate 2 afterwards.In this operation, utilize the oxidation kind that generates from oxidizing solution with the polysilicon direct oxidation, form the film (Fig. 2 (c)) of silicon dioxide film 41.In addition, in this case, formed polysilicon processed substrate 2 afterwards and become the substrate that will form chemical oxide film.In addition, the oxidation kind that so-called " direct oxidation " expression for example utilizes oxidizing solution forms chemical oxide film after with polysilicon 51 oxidations own, rather than forms oxide-film by deposition as the CVD method.

Then, further utilize the oxidation kind to make polysilicon 51 oxidations, make silicon dioxide film 41 make silicon dioxide film 42 growths (Fig. 2 (d)) along the direction of processed substrate 2.In addition, in Fig. 2 (d), give different symbols for the silicon dioxide film 42 after the silicon dioxide film 41 of distinguishing initial formation and the growth.

Then, utilizing after sputtering method formed the film of the grid material that becomes grid 3, utilize photoetching on this film, to form the resist of gate pattern.Carry out composition then, form grid 3, gate insulating film 4 and semiconductor film 5 (Fig. 2 (e)).Grid material can use for example polysilicon, amorphous silicon, discontinuous crystal grain border silicon metal (CG silicon), metal (Al, Ti, Ta etc.) etc.

At last, utilize the P-CVD method to form silicon nitride film, utilize photoetching and dry etching remove on the pixel electrode 8 in this silicon nitride film and the part on the portion of terminal pad (not shown) to form diaphragm 9, finish thin-film transistor 1 (Fig. 2 (f)) thus.

In this manufacture method, processed substrate 2 is impregnated into formation grid oxidation film 4 in the oxidizing solution.Therefore, even substrate surface has concavo-convex or curved surface, oxidizing solution also can spread all over substrate surface equably.Thus, in the Zone Full that will form silicon dioxide film 41,42, can both form the silicon dioxide film 41,42 of uniform film thickness.And then silicon dioxide film 42 is grown to processed substrate 2 directions.Therefore, silicon dioxide film 42 is changing with the interface of polysilicon 51 (grid oxidation film 4 and semiconductor layer 5) always, forms chemical oxide film simultaneously, can make this interface cleaning thus.Grid oxidation film 4 is improved with the interfacial characteristics of semiconductor layer 5.Therefore, can be formed in the high high-quality grid oxidation film 4 of reliability of characteristic aspect excellences such as insulation tolerance.Can make grid oxidation film 4 realize filmings (being the filming of thin-film transistor 1 self) thus.

And then, even this manufacture method also can form high-quality grid oxidation film 4 under the cryogenic conditions below 200 ℃.In addition, can use and processed substrate 2 is impregnated into short-cut method such in the oxidizing solution forms chemical oxide film.Therefore, do not need such being used for of CVD method to realize the large-scale device and the equipment of vacuum condition etc.

As mentioned above, in this manufacture method,, can in will forming the whole zone of grid oxidation film 4, form the grid oxidation film 4 of uniform film thickness by the carrying out of oxide-film formation operation.Therefore, can form high reliability, high-quality grid oxidation film 4.In addition, oxide-film formation operation can be carried out under the low temperature below 200 ℃.Therefore, for example also can produce the plastic film transistor that hangs down threshold value on the plastic base.And then, because the uniform film thickness of grid oxidation film 4 and excellent quality, so this thin-film transistor 1 thin-film transistor that is a kind of high-performance and high reliability.

In addition, this thin-film transistor also can adopt thin-film transistor for example shown in Figure 20 1 ' such structure except quadrature shift thin-film transistor 1 shown in Figure 1.Thin-film transistor 1 ' also be staggered (quadrature shift) thin-film transistor.In the thin-film transistor 1 of Fig. 1, source electrode 6 is formed on the processed substrate 2 with drain electrode 7, and different therewith is, the thin-film transistor 1 of Figure 20 ' in be formed in and be used for being formed on the position of separating on the dielectric film 17 of resolution element with semiconductor layer 5.In addition, in Fig. 1, do not show, and in Figure 20, expressed zone, source region 16 and the drain region 18 (n for example of the impurity that in semiconductor, mixed at the two ends of semiconductor layer 5 ⁺Polysilicon (n ⁺P-Si)).In addition, thin-film transistor 1 ' in, having only the gate insulating film 4 between semiconductor layer 5 and the grid 3 is by the high-performance chemical oxide-film after semiconductor layer 5 direct oxidations is constituted.On gate insulating film 4, formed the deposition SiO that forms by depositions such as CVD methods ₂Film 19.All the time, grid oxidation film 4 and deposition SiO ₂The part of film 19 forms by the CVD method, and therefore, the quality and the reliability of grid oxidation film 4 are low.Different therewith is, as thin-film transistor 1 ' shown in, use the chemical oxide film of direct oxidation to constitute like that according to Fig. 2 (c) Fig. 2 (d) grid oxidation film 4, just can improve the quality and the reliability of grid oxidation film 4.

In addition, be illustrated at staggered thin-film transistor in the above description, but also can be the reciprocal cross shift.

Then, the characteristic that describes this manufacture method in detail is the formation (oxide-film forms operation: Fig. 2 (c) Fig. 2 (d)) of grid oxidation film 4.

In this manufacture method, oxide-film forms operation and mainly contains 2 kinds of methods.

(1) passes through the method (2 stage oxidizing process) that 2 stages form grid oxidation films.

(2) by applying the method (voltage applies method) that voltage forms grid oxidation film.

The following describes this two kinds of methods.

(1) 2 stage oxidizing process

Thereby 2 stage oxidizing process are to be impregnated in the solution that comprises the different active oxidation kind of concentration forming the 1st oxide-film 4a (the 1st operation) by the processed substrate 2 that will form grid oxidation film 4 to form the 2nd oxide-film 4b (the 2nd operation) afterwards again, form the method for gate insulating film by stages.

2 stages oxidizing process utilization device for example shown in Figure 9 is implemented.Fig. 9 is a profile of carrying out the device of 2 stage oxidizing process, has simply represented here as forming the device of silicon dioxide film as chemical oxide film on the silicon substrate 10 of processed substrate 2.Promptly, it constitutes: the silicon substrate 10 (the processed substrate 2 of Fig. 2) of processed usefulness is impregnated in the low concentration oxidizing solution (low concentration oxidizing solution) 30 in first treatment trough 20, on silicon substrate 10 surfaces, form the 1st oxide-film 40 (being equivalent to the 1st oxide-film 4a among Fig. 1 and Fig. 2 (f)) afterwards thus, the silicon substrate 10 that has formed the processed usefulness of the 1st oxide-film 40 is impregnated in the oxidizing solution (high concentration oxidizing solution) 60 of the high concentration in second treatment trough 50, it is (not shown in Fig. 9 further to form the 2nd oxide-film thus on the 1st oxide-film 40, the 2nd oxide-film 4b that is equivalent to Fig. 1), finally form silicon dioxide film 70 (gate insulating film 4 that is equivalent to Fig. 1).That is, this manufacturing installation has constituted the oxide-film formation portion that utilizes 2 stages oxidizing process enforcement oxide-film formation operation that describes in detail in the back.

The 1st operation in the 2 stage oxidizing process is that the processed substrate 2 that silicon substrate is used as the grid oxidation film 4 that will form among Fig. 1, Fig. 2 is impregnated into the operation that forms the 1st oxide-film 4a of porous matter (atomic density is low) in the solution of the oxidizing solution that comprises relative low concentration thus.

On the other hand, the 2nd operation is that the silicon substrate that will form the 1st oxide-film 4a is impregnated into the operation that forms the 2nd thick oxide-film 4b than the 1st oxide-film 4a in the solution (high concentration oxidizing solution) that contains concentration and be higher than the active oxidation kind of the 1st operation thus.

According to this kind mode, by processed substrate 2 is impregnated in the oxidizing solution of concentration variable concentrations from low to high, at first the oxidizing solution by low concentration carries out oxidation, to form the 1st oxide-film 4a of porous matter (atomic density is low).Then, utilize the oxidation of the oxidizing solution of high concentration, the catalyst action by means of the 1st oxide-film 4a of this porous matter promotes the formation of the 2nd oxide-film 4.Thus, the grid oxidation film 4 of final formation is formed uniformly.

Form in the operation at the above-mentioned oxide-film that uses 2 stage oxidizing process, the concentration of the oxidizing solution of above-mentioned low concentration preferably is lower than azeotropic concentration, and the concentration of the oxidizing solution of above-mentioned high concentration is azeotropic concentration preferably.Under the situation of azeotropic concentration, the composition of solution is constant.Therefore, after the oxidizing solution that utilization is lower than the low concentration of azeotropic concentration has formed the 1st oxide-film 4a of porous matter, utilize the oxidizing solution of the high concentration of azeotropic concentration to form the 2nd oxide-film 4b, just can form uniform gate insulating film 4.

Use the above-mentioned oxide-film formation operation of 2 stage oxidizing process also can be used as above-mentioned high concentration oxidizing solution in above-mentioned low concentration oxidizing solution heating back.In the structure of Fig. 9, be provided with first treatment trough 20 of the oxidizing solution 30 that is used for holding low concentration and be used for holding second treatment trough 50 of the oxidizing solution 60 of high concentration.Relative therewith, if the oxidizing solution 30 of low concentration is heated to the concentration of the oxidizing solution 60 of high concentration, then do not need second treatment trough 50.Therefore, can simplify the structure of the oxide-film formation portion that is used for carrying out the oxide-film formation operation of using 2 stage oxidizing process.

Enumerate instantiation below and further describe 2 stage oxidizing process.In 2 stage oxidizing process, the processed substrate 2 (silicon substrate 10) that to handle in the operation of Fig. 2 (b) utilizes after the ultra-pure water rinsing (cleaning) 5 minutes, and processed substrate 2 is impregnated in the low concentration oxidizing solution 30 that is contained in first treatment trough 20 shown in Figure 9.Thus, shown in Fig. 2 (c), formed silicon dioxide film 41 (the 1st oxide-film (the 1st chemical oxide film)).In addition, the dip time here is decided to be 10 minutes.According to this kind mode, the surface was flooded 10 minutes in the oxidizing solution 30 of low concentration through the processed substrate 2 after clean the processing, formed the silicon dioxide film 41 shown in Fig. 2 (c).In addition, silicon dioxide film 41 is the chemical oxide films after utilizing the oxidation kind with polysilicon 51 oxidations.

In addition, the oxidizing solution 30 of low concentration is that concentration is low and solution (oxidizing solution) that oxidizing force is strong.Here, the oxidizing solution working concentration is the aqueous solution of nitric acid of 40% (weight ratio, below note is done " wt ").In addition, the thickness of the 1st oxide-film 4a is decided to be 1.1nm.

Then, in Fig. 2 (d), will in the operation of Fig. 2 (c), form silicon dioxide film 41 processed substrate 2 afterwards and be impregnated in the oxidizing solution 60 that is contained in the high concentration in second treatment trough 50 shown in Figure 9.Thus, shown in Fig. 2 (d), the oxidation reaction of polysilicon 51 is further carried out, and forms silicon dioxide film 42.That is,, constantly form new interface between polysilicon 51 and the silicon dioxide film 42 along with the carrying out of oxidation reaction.That is, silicon dioxide film 42 and the interface of polysilicon 51 are always clean.This silicon dioxide film 41,42 becomes the 1st oxide-film 4a, the 2nd oxide-film 4b, finally becomes grid oxidation film 4.That is, silicon dioxide film 41,42 is made of the 1st oxide-film 4a and the 2nd oxide-film 4b in form, but because therefore the silicon dioxide of both after to be polysilicon 51 oxidized be actually 1 layer of silicon dioxide film (grid oxidation film 4).In addition, the dip time here is decided to be 10 minutes.According to this kind mode, flooded 10 minutes in the oxidizing solution 60 of high concentration having formed the 1st oxide-film 4a processed substrate 2 afterwards, be formed uniformly the silicon dioxide film 41,42 shown in Fig. 2 (d).Here, the total thickness of silicon dioxide film 41,42 is decided to be 10nm.

In addition, the oxidizing solution 60 of high concentration is concentration height and the strong solution (oxidizing solution) of oxidizing force.Here, working concentration is the oxidizing solution of the azeotropic nitric acid of 68% (wt) as high concentration.

Then, carry out after the predetermined matting and drying process, on silicon dioxide film 41, form the film of grid material.Here, this grid material is that the aluminium alloy of the silicon by will containing 1 percentage by weight forms (following this metal film electrode simply is called the A1 electrode) by the thickness that known impedance heated vapour deposition method is deposited as about 200nm.In addition, grid material is not limited to the A1 electrode, also can use polysilicon electrode (material) to replace this grid material by for example adhering to.

, as Fig. 2 (e) shown in, grid material be patterned into reservation shape, produce the resist of gate pattern thereafter.

At last, utilize the P-CVD method to form silicon nitride film, utilize photoetching and dry etching remove on the pixel electrode 8 in this silicon nitride film and the part on the portion of terminal pad (not shown) to form diaphragm 9, make thin-film transistor 1 (Fig. 2 (f)).According to this kind mode manufactured thin film transistor is the MOS transistor npn npn.

As shown in Figure 3, this thin-film transistor has stable capacitance (electrostatic capacitance).Fig. 3 be the electrostatic capacitance (C) of the thin-film transistor that obtains in the present embodiment with the relation that applies voltage (V), be the C-V performance plot.Shown in this performance plot, on grid 3, apply positive voltage, on the interface of semiconductor layer 5 and grid oxidation film 4, bring out inversion layer thus, obtain stable capacitance (electrostatic capacitance).

According to this kind mode, in this example, processed substrate 2 is impregnated in the different aqueous solution of nitric acid of concentration, on processed substrate 2, form silicon dioxide film 41,42 thus by 2 stages.That is to say, formed the silicon dioxide film 41,42 of the grid oxidation film 4 that is used for constituting thin-film transistor by means of following operation: to make concentration be the aqueous solution of nitric acid (oxidizing solution of low concentration) of 40% (wt) thus touch processed substrate 2 forms the 1st oxide-film 4a (the 1st chemical oxide film) on the surface of the polysilicon 51 on the processed substrate 2 (semiconductor layer 5) operation; And make the high concentration aqueous solution of nitric acid (oxidizing solution of high concentration, the aqueous solution of nitric acid of above-mentioned 68% (wt)) of concentration 40% (wt) used when forming the 1st oxide-film 4a thus contact the operation that forms the 2nd oxide-film 4b from the 1st oxide-film 4a to processed substrate 2 directions.

In addition, C-V performance plot according to Fig. 3 also can be understood, the leakage current density of the thin-film transistor that forms according to this kind mode also is equal to or higher than the leakage current density characteristic of the mos capacitance device that silicon dioxide film that use forms with common high-temperature thermal oxidation method forms as dielectric film, and its high-performance is positively approved.

In addition, in above-mentioned manufacturing example, the thickness of silicon dioxide film 41,42 is decided to be 10nm, but this thickness there is no specific restriction.By regulating the time in the oxidizing solution 60 that processed substrate 2 is impregnated into the oxidizing solution 30 of low concentration and high concentration, just can change the thickness of the 1st oxide-film 4a, the 2nd oxide-film 4a and grid oxidation film 4.In other words, setting the time that processed substrate 2 is impregnated in the oxidizing solution according to the thickness of expectation gets final product.In addition, the formation speed of each chemical oxide film also changes along with the concentration difference of oxidizing solution.Therefore, dip time is set according to the thickness of the oxide-film of the kind of oxidizing solution, concentration, formation and is got final product, and does not have specific restriction.

In addition, the oxidizing solution of low concentration or oxidizing gas are that the aqueous solution of nitric acid of 40% (wt) is that example is illustrated with concentration, also can replace and use at least a aqueous solution that is selected from following group: the mixed solution and the chloroazotic acid of mixed solution, sulfuric acid and the nitric acid of mixed solution, ammoniacal liquor and the hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of mistake chloric acid, sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide, and then also can use boiling water with oxidizing force.

Wherein, nitric acid is not halogen-containing because of it, thereby can prevent that the generation of chlorine etc. from causing harmful effect to manufacture process.Therefore, oxidizing solution nitric acid preferably.And then this nitric acid is preferably highly purified.Use highly purified nitric acid, just can form better chemical oxide film.This highly purified nitric acid can use the enough low nitric acid of concentration of metal impurities contained in the nitric acid for example.For example, the concentration of impurity is below 10ppb, preferably below 5ppb, more preferably below 1ppb.

In addition, in the present embodiment, using concentration of nitric acid is oxidizing solution or the oxidizing gas of the aqueous solution of nitric acid (so-called azeotropic nitric acid) of 68% (wt) as high concentration, also can replace use and cross at least a aqueous solution of selecting the group of chloric acid, azeotropic sulfuric acid and chloroazotic acid from azeotropic.

In addition, if the azeotropic mixture of use and water is as the oxidizing solution of high concentration, then have fixing concentration respectively in this solution and steam (being gas) the chemical oxide film forming process on semiconductor layer (polysilicon 51), can control the growth of chemical oxide film by time management.Therefore, the oxidizing solution of high concentration azeotropic mixture preferably.

In addition, as described later, utilize the 1st chemical oxide film (the 1st oxide-film 4a) of the oxidizing solution formation of low concentration preferably to have hole (pore).That is the 1st chemical oxide film lower film of atomic density preferably.Thus, just can carry out smoothly by means of the formation of the 2nd chemical oxide film of the oxidizing solution of high concentration.This is because the effect (contact) owing to oxidizing solution in the hole in the 1st chemical oxide film has formed the 2nd chemical oxide film.That is, the 1st chemical oxide film that contains the low atomic density of hole becomes catalyst, and the film formed oxidation reaction of the 2nd chemical oxidation is carried out successively, therefore, can form more high-quality chemical oxide film.

In addition, in the above description, as shown in Figure 9, form chemical oxide film by means of the low concentration oxidizing solution 30 and the high concentration oxidizing solution 60 (oxidizing solutions of 2 kinds of concentration) that are contained in respectively in the 1st treatment trough 20 and the 2nd treatment trough 50.But the formation method of chemical oxide film is not limited to this, also can be for example to divide a plurality of stages (oxidizing solution or its gas of preparing concentration more than 2 kinds) to switch to high concentration successively from above-mentioned low concentration.

In addition, the concentration of oxidizing solution is risen from low to high continuously.That is, also low concentration solution can be concentrated, transition is a highly concentrated solution continuously thus.For example, the oxidizing solution (oxidizing solution of low concentration) that will be lower than azeotropic concentration is heated to azeotropic concentration and concentrates, and keeps this heated condition, and thus, the oxidizing solution that reaches azeotropic concentration has just formed fixing solution composition, steam is formed.Thus, just can control the growth of chemical oxide film by time management.Therefore, can be with the formation (thickness and quality) of higher precision control chemical oxide film.

That is, under the situation that the concentration that makes oxidizing solution rises from low to high continuously, above-mentioned oxide-film formation operation also be we can say and is comprised following operation: substrate is impregnated in the oxidizing solution that is lower than azeotropic concentration to form the operation of the 1st oxide-film; Under the state in substrate being impregnated into the above-mentioned oxidizing solution that is lower than azeotropic concentration the above-mentioned oxidizing solution that is lower than azeotropic concentration is concentrated into azeotropic concentration, on the 1st oxide-film, forms the operation of the 2nd oxide-film thus.

In the method, at first use the oxidizing solution that is lower than azeotropic concentration to form the 1st oxide-film.Secondly, under the state that substrate is impregnated into this oxidizing solution, this oxidizing solution is concentrated into azeotropic concentration.Thus, after forming the 1st oxide-film, the concentration by improving oxidizing solution continuously is to form the 2nd oxide-film.Each oxide-film is to use the different oxidizing solution of concentration to form, so its atomic density difference.That is to say that the atomic density Billy who utilizes the 1st oxide-film that the oxidizing solution of the low concentration be lower than azeotropic concentration forms is low with the atomic density of the 2nd oxide-film that the oxidizing solution of the high concentration of azeotropic concentration forms.Therefore, above-mentioned chemical oxide film has the structure that atomic density distributes.

As described later, substrate is being impregnated under the state of oxidizing solution, the concentration that makes oxidizing solution rises to high concentration continuously from low concentration and forms the words of chemical oxide film, the oxidizing solution different with using the independent concentration that is provided with forms the situation of chemical oxide film and compares, and can form thick chemical oxide film at short notice.

In addition, the oxidizing solution of above-mentioned low concentration and the high concentration oxidation kind that preferably oxidizing force is strong (for example ion or the atomic group of oxygen such as oxonium ion, hydroxide ion, peroxide ion).Thus, just can form chemical oxide film below 200 ℃.Therefore, also can be applied to the formation of TFT in need manufacture process in the LCD of the flexibility that forms chemical oxide film below 200 ℃.

In the present embodiment, at above-mentioned silicon dioxide film 41,42, can be formed in the nitrogenous gas, especially make the part on surface be converted into the silicon dioxide film that contains silicon nitride after the silicon nitride, perhaps utilize CVD method etc. on the film that contains silicon nitride behind the above-mentioned nitrogen treatment, to overlap to form thick SiO by plasma nitridation process ₂Deng dielectric film.

The nitrogenize chemical oxide film has and its composition character between oxide-film and nitride film accordingly basically.For example, and compare in the oxide-film, the diffusion coefficient of the impurity in the nitride film less (hot nitrogenize), therefore, excellent performance aspect the diffusion of impurity (particularly boron) in the Si substrate that the nitrogenize chemical oxide film mixes in stoping grid.Therefore, the nitrogenize chemical oxide film can be applied in the thin-film transistor of gate insulating film (for example 4nm is following) that need be as thin as a wafer.

According to this kind mode, nitrogen treatment is a kind of method that improves transistor performance, can further improve the membranous of chemical oxide film by means of this nitrogen treatment.Therefore, can realize the filming of chemical oxide film.

In addition, so-called " carrying out nitrogen treatment " is that at least a portion of formed silicon dioxide film 41,42 (chemical oxide films) is carried out nitrogenize.That is, nitrogen treatment is, to heat in the atmosphere that contains the nitrogenize kind after forming chemical oxide film in the oxidation that utilizes semiconductor surface, thus at least a portion of chemical oxide film is carried out the processing of nitrogenize.

Nitrogen treatment can be ammoniacal liquor (NH ₃) nitrogenize, nitrous acid (N ₂O) nitrogenize, nitric oxide (NO) nitrogenize etc.In these methods, the nitrogenize kind is ammoniacal liquor, nitrous acid, nitric oxide.In addition, the nitrogenize chemical oxide film by NO nitrogenize gained can not reduce performance, and performance is excellent aspect life-span of the insulation breakdown tolerance level of gate insulating film, hot carrier tolerance level.

Other examples of present embodiment are at above-mentioned silicon dioxide (SiO ₂) stacked high dielectric film, for example hafnium oxide, aluminium oxide etc. form on the film 41,42 composite membrane, can be used in the gate insulating film of MOS transistor thus.In the case, compare, can realize that the performance of transistor characteristic improves (improving mobility etc. by reducing leakage current, reduction interface energy level etc.) with the situation of only using high dielectric film.The silicon dioxide film that forms below above-mentioned high dielectric film can be 1nm or smaller or equal to the film as thin as a wafer of 1nm for example.In addition, utilize silicon dioxide film that common thermal oxidation method forms if about 1nm, then leakage current or interface energy level are very big and be not enough to practicality, but the silicon dioxide (SiO of present embodiment ₂) film 41,42 also goes for forming the composite membrane of the stepped construction of thick insulating film thereon.And then, be not only above-mentioned high dielectric film, the oxide-film of present embodiment also can be applied to ferroelectric thin film is stacked and in the structure that forms.

In addition, in the above description, grid 3 has used aluminium, and the film that contains metallic atom can be the film that contains the metallic atom of electing among the group of aluminium, magnesium, nickel, chromium, platinum, palladium, tungsten, titanium and tantalum.In addition, the film that contains metallic atom preferably contains the film of reactive metal atom, for example, and preferably metal film or siliceous aluminum films such as aluminium, magnesium, nickel.In addition, the film that contains metallic atom also can use compounds such as titanium nitride or tantalum pentoxide.And then, also can use the silicon compound electrode of nickeliferous grade.

In addition, the operation of each described in the present embodiment also be applicable to form polycrystalline (containing tiny crystal grains) on the glass substrate or on the substrate such as PET thus silicon or amorphous silicon form the situation of thin-film transistor (TFT).That is, preferably processed substrate contains silicon, the chemical oxide film that will form is silicon dioxide film.

In addition, processed substrate is not limited to flat shape, in 3D shape or have on the substrate of the concavo-convex or curved surface of sphere, concavo-convex or curved surface area is as transistorized raceway groove with it, also can be at low temperatures be formed uniformly the dielectric films such as silicon dioxide film described in the present embodiment at this on the concavo-convex or curved surface.

And then above-mentioned each operation is not limited to make the situation of thin-film transistor, also can be applied to manufacture process, mos capacitance device of the capacitor insulating film of memories such as large scale integrated circuit (LSI), for example flash memory etc.In addition, in the above description, formed silicon dioxide film, but chemical oxide film changes along with the material category of oxidized semiconductor layer 5, be not limited to silicon dioxide film as chemical oxide film.

In addition, in the above description, on processed substrate 2, do not apply voltage; Form silicon dioxide film by applying voltage, just can accelerating oxidation the carrying out (can improve the formation speed of silicon dioxide film) of reaction.

In addition, in 2 stage oxidizing process, processed substrate is immersed in the oxidizing solution 30,60 of low concentration and high concentration.Therefore, can form oxide-film with very simple structure.But, might not flood silicon substrate 11, as long as make oxidizing solution generation effect on processed substrate.For example, can adopt in the steam (oxidizing gas) of the oxidizing solution that is exposed to low concentration or high concentration.In this case, use the steam of above-mentioned oxidizing solution to get final product.

Further describe the present invention below by making example, but the present invention is not limited thereto.

[making example 1]

The method formation thickness that describes below with 2 stages solution oxides formation chemical oxide film is the SiO of 3.5nm ₂The situation of film.

At first, in order to form the 1st chemical oxide film (silicon dioxide film 41), processed substrate 2 is impregnated in the aqueous solution of nitric acid of 40% (wt) under the state that does not apply voltage, and having formed thickness is that atomic density 1.1nm, porous, that atomic density is relatively low is 2.22 * 10 ²²Atom/cm ³SiO ₂Film (the 1st oxide-film 4a; Chemical oxide film) 41.

Then, in order to form the 2nd chemical oxide film, the substrate that has formed silicon dioxide film 41 is kept being immersed in the state in the aqueous solution of nitric acid of above-mentioned 40% (wt), be heated to the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of concentration of nitric acid 68% (wt), formed than the 1st chemical oxidation thickness, atomic density is 2.34 * 10 ²²Atom/cm ³SiO ₂Film 42 (whole thickness is 3.5nm).

Can think, in the above-mentioned the 1st and the 2nd oxidizing process (the formation operation of the 1st and the 2nd chemical oxide film), the SiO of the 1st chemical oxide film that in the aqueous solution of nitric acid of initial 40% (wt), forms ₂Existing hole becomes the place that nitric acid decomposes in the film,, contains the above-mentioned SiO of the low atomic density of this hole that is ₂ Film 41 becomes catalyst, forms SiO ₂The nitric acid oxidation of film 42 (the 2nd chemical oxide film) carries out successively.

Fig. 4 represents formed SiO in the nitric acid oxidation process in above-mentioned 2 stages ₂The XPS spectral characteristic figure of film 41,42 (chemical oxide film), 2 sharp-pointed peak values are to be formed by the photoelectron that discharges at Si (2p) track that sends from silicon substrate, the peak value of amplitude broad is by from above-mentioned SiO ₂The photoelectron that film 41,42 discharges forms.Areal intensity ratio according to these peak values can be obtained above-mentioned SiO ₂The whole thickness of film 41,42 is 3.5nm.

Relative therewith, if do not form the 1st chemical oxide film, from just begin at first with the same formation condition of above-mentioned the 2nd chemical oxide film under silicon substrate is impregnated into the azeotropic aqueous solution of nitric acid that concentration of nitric acid is 68% (wt), determining to form does not have the very high SiO of hole, atomic density ₂Film, thickness also can hang down and reach 1.4nm.

Fig. 5 is that to have the thickness that is obtained in the nitric acid oxidation process in above-mentioned 2 stages be the SiO of 3.5nm ₂The I-V performance plot of the MOS structure diode of film 41,42 before and after PMA handles.This expression is implemented PMA with 250 ℃ and is handled in hydrogen atmosphere under the state of MOS structure diode, thus, the leakage current density when forward bias 1V and reverse bias-1V becomes 1 * 10 respectively ^-4A/cm ²With 2 * 10 ^-6A/cm ², be respectively 1 * 10 before handling with PMA ^-3A/cm ²With 7 * 10 ^-4A/cm ²Each value compare, leakage current density has positively reduced.

Fig. 6 is that to have the thickness that is obtained in the nitric acid oxidation process in above-mentioned 2 stages be the SiO of 3.5nm ₂The C-V performance plot of the MOS structure diode of film 41,42 before PMA handles.In this C-V performance plot, can observe the knurl (expansion of characteristic is heaved) that interface energy level causes, also exist sluggishness simultaneously.By this diode is directly carried out heat treated with 250 ℃ in hydrogen atmosphere, promptly implement so-called PMA and handle, just can eliminate above-mentioned knurl fully, and sluggishness disappears substantially also.

In this embodiment, at thickness be the SiO of 3.5nm ₂Form grid 3 on the film 41,42, then,, eliminate interface energy level or SiO by in hydrogen atmosphere, handling with 250 ℃ of PMA that heat ₂In between gap level, and then by increasing SiO ₂The band gap of film 41,42 significantly reduces leakage current density, can improve the performance of dielectric film; But be not limited to this example, rule of thumb, by prolonging the dip time in aqueous solution of nitric acid, SiO ₂The thickness of film 41,42 can be increased to tens of nm, and, by being handled, above-mentioned PMA is selected in the hundreds of ℃ of appropriate values about (for example 450 ℃), just can improve the electrical characteristic of MOS structure, particularly can realize sluggish elimination, the reduction of leakage current density, the raising that insulation breakdown is withstand voltage.

What Fig. 7 represented is: in order to form the 1st chemical oxide film silicon substrate 11 is impregnated under the state that does not apply voltage in the aqueous solution of nitric acid of 40% (wt), having formed thickness is that atomic density 1.1nm, porous, that atomic density is relatively low is 2.22 * 10 ²²Atom/cm ³SiO ₂After the film (the 1st chemical oxide film) 41, follow in the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) that is immersed in concentration of nitric acid 68% (wt) in order to form the 2nd chemical oxide film and formed SiO ₂Under the situation of film 41,42, dip time in azeotropic nitric acid and SiO ₂The relation of the thickness of film 41,42.Hence one can see that, SiO ₂The thickness of film 41,42 is along with almost orthoscopic increase of dip time, and can form thickness is the above SiO of 10nm ₂Film 41,42.

In addition, above-mentioned 2 stage nitric acid oxidation processes will be except will switching with the rising in 2 stages in the stage from the low concentration to the high concentration, the multistage that embodiments of the present invention also comprise from the low concentration to the high concentration switches successively or switches continuously from the low concentration to the high concentration, for example, keeping being immersed in the state that seethes with excitement in the aqueous solution of nitric acid of 40% (wt) is the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of 68% (wt) up to concentration of nitric acid.

[making example 2]

Illustrate that the of the present invention the 2nd makes example.Utilizing the polysilicon on the substrate to form under the situation of TFT, in its gate insulating film, use stacked silicon dioxide film (SiO ₂).Therefore, the example of being narrated (making example 2) forms silicon dioxide film on the polysilicon on substrate (being that silicon substrate 11 is polycrystalline silicon substrates) similarly here, produces mos capacitance device (its capacitor insulating film) thus.

In this case, can form silicon dioxide (SiO by the nitric acid oxidation process in 2 stages on the polysilicon surface on the substrate ₂) film.

1 identical with above-mentioned manufacturing example (with reference to Fig. 2 (a) to Fig. 2 (f)), at first in order to form the 1st chemical oxide film, polysilicon layer on the substrate is impregnated under the state that does not apply voltage in the aqueous solution of nitric acid of 40% (wt) (making its contact), having formed thickness is the SiO of 1.1nm ₂Film (chemical oxide film) 41 (Fig. 2 (c)).

Then, in order to form the 2nd chemical oxide film, will have above-mentioned the 1st chemical oxide film (SiO ₂Film 41) polysilicon layer on the substrate is impregnated into the concentration of nitric acid that (make its contact) be in fluidized state under the state that does not apply voltage be the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of 68% (wt), generates the 2nd thicker chemical oxide film (SiO ₂), be formed uniformly the SiO that whole thickness is 25nm thus ₂ Film 41,42 (chemical oxide film) (Fig. 2 (d)).

In this case, example 1 is identical with making, by form each oxidizing process of the above-mentioned the 1st and the 2nd chemical oxide film, the SiO of the 1st chemical oxide film that forms in the aqueous solution of nitric acid of initial 40% (wt) ₂Existing hole becomes the place that nitric acid decomposes in the film, that is, the atomic density of porous is relatively low, and (atomic density is 2.22 * 10 ²²Atom/cm ³About) the SiO of above-mentioned the 1st chemical oxide film ₂Film 41 becomes catalyst, and the nitric acid oxidation that forms the 2nd chemical oxide film 42 carries out successively, and the density that has generated ratio the 1st chemical oxide film is high slightly, and (atomic density is 2.34 * 10 ²²Atom/cm ³About) and than the 1st chemical oxide film thicker the 2nd chemical oxide film (SiO ₂Film 42).

Then, at this silicon dioxide film (chemical oxidation SiO ₂Film) material of last film forming grid 3.Thereafter, the wiring pattern formation grid 3 with reservation shape produces mos capacitance device (Fig. 2 (f)) thus.

Every characteristic of the mos capacitance device that in making example 2, is obtained each all the manufacturing example 1 with above-mentioned is identical, present high-performance, high stability.

In addition, what this example was narrated is to use aqueous solution of nitric acid as oxidizing solution, also can replace to use at least a aqueous solution that is selected from following group: mixture-aqueous sulfuric acid, chloroazotic acid and their mixed solution (comprising azeotropic mixture) of crossing mixture-mistake chloric acid aqueous solution, sulfuric acid and the water of chloric acid and water.

In addition, in making example 2, also can use by nitrogen treatment above-mentioned silicon dioxide film 41,42 (chemical oxide films; SiO ₂Film) a part is converted into the composite membrane after the silicon nitride film that thickness is 0.3～0.5nm.

Narration is the example of mos capacitance device in making example 2, under the situation of the gate insulating film that forms MOS transistor, use this silicon dioxide film or silicon dioxide film is carried out silicon nitride film behind the nitrogen treatment, just can obtain the few high performance dielectric film of interface energy level, for example can be used for large scale integrated circuit (LSI) or charge-coupled device (CCD) etc.In addition, also can be used for using polysilicon and the capacitor insulating film of memories such as the interlayer dielectric of the Miltilayer wiring structure that forms or flash memory, believe in these fields and can be widely used in wiring.

In addition, the monocrystalline silicon substrate that is to use of explanation is made the example of mos capacitance device as processed substrate in making example 2, each operation as described herein is not limited to use the situation of monocrystalline silicon substrate, also be applicable to utilize on the glass substrate or substrate such as PET on polycrystalline (comprising crystallite) silicon or amorphous silicon, CG silicon (the discontinuous crystal grain border silicon metal) situation that forms thin-film transistor (TFT).Especially, in making example 2, owing to can form chemical oxide film below 200 ℃, therefore, also be applicable to the formation of the TFT in the manufacture process of the LCD of flexibility.

And then above-mentioned each operation is not limited to make the situation of mos capacitance device, also can be applied to use possess on gate insulating film, be layered in formed silicon dioxide film in the present embodiment, the formed SiO of the stacked CVD of utilization method on it ₂The stacked silicon dioxide film of film or in the middle of above-mentioned stacked silicon dioxide film, insert any one the gate insulating film of MOS transistor, large scale integrated circuit (LSI) and charge-coupled device (CCD) etc. or interlayer dielectric etc. of the multilayer film of the film contain silicon nitride.

In making example 2, except above-mentioned silicon dioxide film 41, outside 42 the formation, also can by the film that its surface is contained silicon nitride form to handle or nitrogen plasma in nitrogen treatment at above-mentioned silicon dioxide film 41,42 surfaces are gone up and are formed the film that contains silicon nitride, and then, also can utilize CVD method etc. to form thick SiO overlapping above the above-mentioned silicon dioxide film 41,42 or above the above-mentioned film that contains silicon nitride ₂Deng dielectric film.

(2) voltage applies method

It is a kind ofly to apply voltage on will forming the processed substrate 2 of grid oxidation film 4 (or polysilicon 51 (semiconductor)), this substrate is impregnated in the solution that contains the active oxidation kind to form the method for grid oxidation film 4 that voltage applies method.

Voltage applies method and can utilize device for example shown in Figure 10 to implement.Figure 10 carries out the profile that voltage applies the device of method, has simply represented here as forming the device of silicon dioxide film as chemical oxide film on the silicon substrate 11 of processed substrate 2.Promptly, its structure is, under the silicon substrate 11 with processed usefulness remains on state in the oxidizing solution 13 that is impregnated in the treatment trough 12, power supply 4 can be connected to silicon substrate 11, and at silicon substrate 11 and be arranged between the opposite electrode 15 in the treatment trough 12 and apply predetermined voltage.That is to say that this manufacturing installation has oxide-film formation portion as follows, the formation method of its enforcement is utilized voltage to apply and is realized that oxide-film forms operation.

The oxide-film that utilizes voltage to apply method forms and to apply voltage on operation will form gate insulating film 4 in Fig. 1, Fig. 2 the processed substrate 2 and carry out.For example,, then, on processed substrate 2, apply voltage, just can on grid 3 surfaces, form grid oxidation film 4 as long as on semiconductor layer 5, apply voltage and processed substrate 2 is conductive materials if processed substrate 2 is insulating properties substrates.If processed substrate 2 is conductive materials, this conductive material has then also been formed grid oxidation film 4 if the oxide that forms by utilizing oxidizing solution constitutes on the surface of processed substrate 2.

Enumerating instantiation below further describes voltage and applies method.Apply in the method at voltage, the processed substrate of handling in the operation of Fig. 2 (b) 2 (silicon substrate 11) is with after the ultra-pure water rinsing (cleaning) 5 minutes, silicon substrate 11 is impregnated into the low concentration that is contained in the treatment trough shown in Figure 10 20 but in the strong solution (oxidizing solution) of oxidizing force, and energized 14 on this silicon substrate 11, and treatment trough 12 in apply the positive voltage of 10V between the opposite electrode 15 that is provided with, kept at ambient temperature about 10 minutes.Here, it is the aqueous solution of nitric acid of 1 mole (mol./l) that oxidizing solution uses concentration of nitric acid, as Fig. 2 (c) (d) shown in, on polysilicon 51, be formed uniformly the silicon dioxide film 41,42 that thickness is about 10nm.In addition,,, also be applied in voltage on source electrode 6, drain electrode 7, the polysilicon 51 here by processed substrate 2 is applied voltage.

Temperature when will consider that to the voltage applying condition of above-mentioned processed substrate 2 heating-up temperature is set to below 200 ℃ this moment and selecting.For instance, the electrode configuration of uniform electric field is provided on the whole surface of above-mentioned processed substrate 2, for example between the opposite electrode of above-mentioned processed substrate 2 and configuration in parallel, at the selected positive potential of above-mentioned processed substrate 2 one sides is the scope (direct current is lower than 100V) of tens of volts, be under the situation of aqueous solution of nitric acid of 1 mole (mol./l) at above-mentioned concentration of nitric acid, suitably be set in the scope of direct current 5～20V and get final product.Apply the O of active oxidation kind by means of this voltage ^-Or OH ^-Be inhaled into the surface of polysilicon 51 Deng anion or atomic group, and silicon dioxide film 41 also can pass herein after being formed, the oxidation reaction on polysilicon 51 surfaces obtains quickening equally.Thus, generated silicon dioxide film 42 on polysilicon 51 surfaces.

In addition, the condition that above-mentioned processed substrate 2 is applied voltage is to apply negative potential thereon, can suppress the oxidation kind thus and be inhaled into polysilicon 51 surfaces.When not applying voltage (promptly applying magnitude of voltage is zero) on the above-mentioned processed substrate 2, because of diffusion arrives the growth that polysilicon 51 lip-deep oxidation kinds cause polysilicon 51 surfaces to go up silicon dioxide film 42, therefore, growth in order to stop polysilicon 51 surfaces to go up chemical oxide film suitably applies negative voltage and gets final product.Be through with silicon dioxide film 42 after polysilicon 51 lip-deep growths, implementing when in the oxidizing solution from treatment trough 12 30, taking out (cutting) processed substrate 2, just can play a role effectively.

Then, on silicon dioxide film 41, formed gate electrode material film.Here, this grid material is that the aluminium alloy of the silicon by will containing 1 percentage by weight forms (following this metal film electrode simply is called the A1 electrode) by the thickness that known resist heating vapour deposition method is deposited as about 200nm.In addition, grid material is not limited to the A1 electrode, also can use polysilicon electrode (material) to replace this grid material by for example adhering to.

, as Fig. 2 (e) shown in, grid material be patterned into reservation shape, produce the resist of gate pattern thereafter.

At last, utilize the P-CVD method to form silicon nitride film, utilize photoetching and dry etching remove on the pixel electrode 8 in this silicon nitride film and the part on the portion of terminal pad (not shown) to form diaphragm 9, make thin-film transistor 1 (Fig. 2 (f)).According to this kind mode manufactured thin film transistor is MOS transistor.

Then explanation is according to the characteristic of the produced MOS transistor of this kind mode.

Figure 11 utilize electrostatic capacitance (C) that voltage applies the MOS transistor that method obtains with the relation that applies voltage (V), be the C-V performance plot.Shown in this performance plot, on grid 3, apply positive voltage, on the interface of chemical oxide film and semiconductor layer, bring out inversion layer thus, obtain stable capacitance (electrostatic capacitance).

In addition, C-V performance plot according to Figure 11 also can be understood, the leakage current density of above-mentioned mos capacitance device also is equal to or higher than the leakage current density characteristic of the mos capacitance device that silicon dioxide film that use forms with common high-temperature thermal oxidation method forms as dielectric film, and its high-performance is positively approved.

In addition, above-mentioned description be to use concentration of nitric acid be 1 mole aqueous solution of nitric acid as oxidizing solution or oxidizing gas, also can replace the mixed solution, sulfuric acid and the hydrogen peroxide that use the nitric acid that is selected from any concentration, cross chloric acid, sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide mixed solution, ammoniacal liquor and hydrogen peroxide mixed solution, sulfuric acid and nitric acid mixed solution, chloroazotic acid and further have at least a solution, its gas or their mixture in the group of boiling water of oxidizing force.That is, these oxidizing solutions or oxidizing gas both can be used alone, but also also mix together.These oxidizing solutions or oxidizing gas can produce the oxidation kind with strong oxidizing force, for example oxonium ion or atomic groups such as oxonium ion, hydroxide ion, peroxide ion.Therefore, the processed substrate 2 by will forming silicon dioxide film 41,42 also can be with on these oxidation kinds introducing polysilicon 51 surfaces (interface between polysilicon 51 and the silicon dioxide film 42) after forming silicon dioxide film 41 as anode.

Using under the situation of aqueous solution of nitric acid as oxidizing solution, even concentration of nitric acid is the low concentration in 1～65% (weight ratio, below note is wt) scope, its oxidizing force to silicon is also very strong, even silicon substrate 11 is not applied voltage, also be suitable for forming above-mentioned silicon dioxide film 41,42.

In addition, the oxidizing solution of high concentration, particularly concentration of nitric acid surpass the high concentration of 65% (wt), for example concentration of nitric acid is that the aqueous solution of nitric acid of 68% (wt) above (azeotropic concentration) is very strong to the oxidizing force of silicon, even processed substrate 2 is not applied voltage, also can form uniform silicon dioxide film 41,42.In addition, utilize this aqueous solution of nitric acid, if heating-up temperature is remained 120.7 ℃ (more than so-called azeotropic temperatures), then the nitric acid Heshui reaches the azeotropic state, the concentration of its solution and steam (being gas) becomes constant respectively, can control the growth of silicon dioxide film 41,42 by time management.

In addition, these steams are that the oxidizing force of oxidizing gas is also very strong, therefore, these steams are played a role under the state that does not apply voltage on the silicon substrate 11, also can (polysilicon 51 surfaces in more detail) go up formation silicon dioxide film 41,42 on processed substrate 2 surfaces.In this case, the temperature of processed substrate 2 can suitably be selected.But, on processed substrate 2, apply voltage and form silicon dioxide film 41,42, can improve the formation speed of silicon dioxide film 41,42 thus.

In addition, in above-mentioned oxidizing solution or its gas, if the oxidizing solution of high concentration or oxidizing gas are to be selected from the azeotropic mixture-azeotropic sulfuric acid of azeotropic mixture-azeotropic nitric acid, sulfuric acid and water of the nitric acid that uses in the present embodiment and water and azeotropic mixture-azeotropic of crossing chloric acid and water is crossed select in the chloric acid at least a, then its oxidizing force is especially strong, is particularly suitable for the formation of oxide among the present invention.Even these azeotropic mixtures are under the situation that applies voltage very low (is zero even apply voltage) on the processed substrate 2, the performance that forms the silicon dioxide film 41,42 that is obtained in the operation at oxide-film all is stable.

According to this kind mode, apply in the method at voltage, above-mentioned oxidizing solution or its gas is the azeotropic mixture of azeotropic concentration preferably, be more preferably the azeotropic mixture with water, further preferably constitute by crossing at least a solution or its gas selected the chloric acid from the azeotropic mixture-azeotropic of the azeotropic mixture-azeotropic sulfuric acid of the azeotropic mixture-azeotropic nitric acid of water, water and water.And then these azeotropic mixtures especially preferably will be heated to azeotropic temperature above above-mentioned oxidizing solution or its gas and act on semiconductor.

In the above description, the oxide-film that applies method enforcement by voltage forms the aqueous solution of nitric acid formation silicon dioxide film 41,42 that operation is used a kind of concentration, also can use oxidizing solution or its gases such as nitric acid of different multiple concentration.In addition, in this case, oxidizing solution or its gas is azeotropic mixture preferably.

That is, it has: make the oxidizing solution or its gas that are lower than azeotropic concentration produce the 1st operation of doing in order to formation the 1st silicon dioxide film (the 1st chemical oxide film) 41 on polysilicon 51 surfaces on the polysilicon 51; The oxidizing solution of azeotropic concentration or its gas are produced do on the 1st silicon dioxide film 41 in order to form the 2nd operation of 2nd silicon dioxide film (2nd chemical oxide film) 42 thicker than the 1st silicon dioxide film 41; At least one operation in above-mentioned the 1st operation and the 2nd operation is utilized above-mentioned voltage to apply method and is carried out oxide-film formation operation (that is, making above-mentioned oxidizing solution or its gas produce work in order to form the 1st and the 2nd chemical oxide film on above-mentioned silicon substrate surface on above-mentioned silicon substrate under the state that has applied voltage on the silicon substrate).That is, utilize the 1st operation of above-mentioned 2 stage oxidizing process and at least one operation in the 2nd operation also can implement by the oxide-film formation operation of utilizing voltage to apply method.

Thus, to form operation identical with the oxide-film of above-mentioned 2 stage oxidizing process, can be formed uniformly the high-quality chemical oxide film of predetermined thickness under low temperature, low pressure condition on the silicon substrate surface.That is, can improve the membranous of silicon dioxide film 41,42, form the very low high-quality silicon dioxide film 41,42 of leakage current density.Therefore, for example silicon dioxide film is being used as under the situation of gate insulating film 4, this silicon dioxide film has played the effect of high-quality dielectric film, therefore, and than the easier realization filming of existing dielectric film (it is following for example to reach several nm).

And then particularly, the 1st operation is implemented under the effect of the oxidizing solution of azeotropic concentration or its gas being lower than azeotropic concentration, the 2nd operation, and therefore, the 1st silicon dioxide film is compared with the 2nd silicon dioxide film, is the lower chemical oxide film of a kind of atomic density.That is, in the 1st operation, can form the 1st silicon dioxide film 41 that has hole.Then, in the 2nd operation, in the 1st operation, make oxidizing solution or its gas generation effect on formed the 1st silicon dioxide film 41 in the existing hole, form the 2nd silicon dioxide film 42 thus.That is, the 1st silicon dioxide film 41 that contains the low atomic density of hole becomes catalyst, and the oxidation reaction of the 2nd silicon dioxide film 42 is carried out successively.Thus, can form the higher silicon dioxide film of quality 41,42.

In addition, the 1st operation and the 2nd operation both can have been prepared 2 kinds of oxidizing solutions of low concentration (preferably being lower than azeotropic concentration) and high concentration (preferably azeotropic concentration) or its gas to form the 1st and the 2nd silicon dioxide film, also can divide a plurality of stages (oxidizing solution or its gas of preparing concentration more than 2 kinds) to switch to high concentration gradually from above-mentioned low concentration.In addition, the concentration of oxidizing solution is risen from low to high continuously.For example, be heated to azeotropic concentration if be lower than the oxidizing solution of azeotropic concentration, by keeping this heated condition, oxidizing solution will reach constant solution composition, steam and form.Thus, just can control the growth of chemical oxide film by time management.Therefore, can be with the formation (thickness and quality) of higher precision control silicon dioxide film.

Apply in the method at voltage, the voltage of silicon substrate 11 is applied the formation speed that improves silicon dioxide film 41,42 on the silicon substrate 11 except meeting, also can promote the increase of its thickness simultaneously.By on processed substrate 2, applying voltage, the oxidation kind-O in the solution ^-Or OH ^-Attracted to the surface of polysilicon 51 Deng anion or atomic group, and after forming silicon dioxide film 41, also pass silicon dioxide film 41 easily and arrival polysilicon 51 surfaces, can improve oxidation reaction speed, obtain thicker silicon dioxide film 42.

Apply the also preferred nitrogenize operation of carrying out nitrogen treatment at above-mentioned silicon dioxide film 41,42 of carrying out in the method at voltage.For example, as the nitrogenize operation, also can be in nitrogenous gas, especially in plasma nitridation process, make silicon dioxide film 41, the part on 42 surfaces is converted into and forms the silicon dioxide film (nitrogenize chemical oxide film) that contains silicon nitride after the silicon nitride, perhaps utilizes CVD method etc. to overlap to form thick SiO on the film that contains silicon nitride behind the above-mentioned nitrogen treatment ₂Deng dielectric film (oxide-film).Thus, silicon dioxide film 41,42 just becomes the film (nitrogenize chemical oxide film) of silicon nitride and silicon dioxide.Carry out insulation breakdown characteristic and charge-trapping characteristic that this nitrogen treatment can improve chemical oxide film.

In addition, applying at voltage also can be at above-mentioned silicon dioxide (SiO in the method ₂) stacked high dielectric film on the film 41-for example hafnium oxide, aluminium oxide etc. form composite membrane, can be used in the gate insulating film 4 of MOS transistor thus.In the case, compare, can realize that the performance of transistor characteristic improves (improving mobility etc. by reducing leakage current, reduction interface energy level etc.) with the situation of only using high dielectric film.The silicon dioxide film 41,42 that (processed substrate 2 one sides) form below above-mentioned high dielectric film can be for example 1nm or thinner very thin films, can not apply voltage and forms.In addition, utilize silicon dioxide film 15 that common thermal oxidation method forms if about 1nm, it is membranous very low, thereby leakage current and interface energy level are very big, are not enough to practicality.

Relative therewith, the silicon dioxide film (SiO of present embodiment ₂Therefore) film 41,42 has high-qualityly, has been suitable for forming the composite membrane of the stepped construction of thick insulating film on silicon dioxide film 41,42.That is the gate insulating film 4 that, is suitable for MOS transistor.And then, be not only above-mentioned high dielectric film, the silicon dioxide film 41,42 of present embodiment is suitable for stacked ferroelectric thin film too and forms.

In addition, applying illustrated in the method at voltage is to use polycrystalline silicon substrates 11 to make the example of mos capacitance devices for forming silicon dioxide film 41,42 required processed substrates, but above-mentioned each operation also is applicable to and is forming polycrystalline (comprising crystallite) silicon, amorphous silicon or CG silicon (discontinuous crystal grain border silicon metal) on the glass substrate or on the substrate such as PET, forming the situation of the thin-film transistor (TFT) with this substrate.

And then, can obtain uniform silicon dioxide film 41,42 in the present embodiment, therefore, above-mentioned processed substrate 2 and polysilicon 51 (semiconductor layer 5) are not limited to flat shape, also can or have on the substrate of the concavo-convex or curved surface of sphere in 3D shape, concavo-convex or curved surface area is as transistorized raceway groove with it.That is, utilize said method, high-quality dielectric film such as formed silicon dioxide film 41,42 is evenly formed at low temperatures corresponding to the concavo-convex or curved surface of processed substrate 2 or polysilicon etc.

And then above-mentioned each operation is not limited to make the such semiconductor device of thin-film transistor.In addition, explanation is the example of thin-film transistor in the present embodiment, under the situation of the gate insulating film that forms thin-film transistor (TFT), by in the middle of this stacked silicon dioxide film or stacked silicon dioxide film, inserting the film that contains silicon nitride, can obtain the few high performance dielectric film of interface energy level, obtain high performance TFT.In addition, also can be used for large scale integrated circuit (LSI) or charge-coupled device (CCD) etc.In addition, also can be used for using polysilicon electrode material etc. and the capacitor insulating film of memories such as the interlayer dielectric of the Miltilayer wiring structure that forms or flash memory, believe in these fields and can be widely used in wiring.

In addition, Shuo Ming the silicon substrate that is to use monocrystalline silicon is made the example of thin-film transistor as processed substrate in the present embodiment, each operation as described herein is not limited to use the situation of monocrystalline silicon substrate, also fully be applicable to utilize on the glass substrate or substrate such as PET on polycrystalline (comprising crystallite) silicon or amorphous silicon, CG silicon (discontinuous crystal grain border silicon metal), carborundum, the SiGe situation that forms thin-film transistor (TFT).Especially, carborundum is suitable for the fast TFT of switching speed, so its value is higher.

In addition, in the present embodiment, be to have applied direct voltage at processed substrate 2, but also can apply alternating voltage.Applying under the situation of alternating voltage,, just can similarly form silicon dioxide film as the situation of direct voltage by pulse control.In addition, by pulse control, also can control the thickness of formed silicon dioxide film.

In addition, grid material has used aluminium in the above description, but the film that contains metallic atom can be the film that contains the metallic atom of electing among the group of aluminium, magnesium, nickel, chromium, platinum, palladium, tungsten, titanium and tantalum.In addition, the film that contains metallic atom preferably contains the film of reactive metal atom, for example, and preferably metal film or siliceous aluminum films such as aluminium, magnesium, nickel.In addition, the film that contains metallic atom also can use compounds such as titanium nitride or tantalum pentoxide.

In addition, voltage is different below applying method and existing anode oxidation method existing.

Existing anode oxidation method is semiconductor to be applied under the state of voltage, form oxide-film on this semiconductor surface.Anode oxidation method is that the semiconductor in a kind of electrolyte that quickens not dissolve oxide-film by electric field becomes moving of segregant, thereby forms the method for oxide-film on semiconductor surface.

For example, utilizing anode oxidation method on the Si substrate, to form SiO ₂Situation under, by the Si substrate is applied voltage, from the Si substrate surface to SiO ₂Film imports Si ⁺Ion.Then, the Si that separates from the Si substrate ⁺Ion passes formed SiO ₂Film moves, and makes the Si that separates thus ⁺Ion arrives SiO ₂The surface of film.In addition, pass through SiO ₂The Si on film surface ⁺The oxidation of ion is at SiO ₂Film forms SiO on the surface ₂Film.That is, in anode oxidation method, SiO ₂The growth of film is at SiO ₂The film surface produces.That is, in anode oxidation method, by to SiO ₂Film surface guiding Si ⁺Ion is at SiO ₂Film causes oxidation reaction on the surface.

Different therewith is to be by using strong oxidizing solution or its gas (hyperoxia voltinism solution or its gas) of oxidizing force, for example forming SiO on the Si substrate in the formation method of oxide of the present invention (this formation method) ₂Under the situation of film, by applying voltage to the Si substrate, separated oxygen ion (O from oxidizing solution ^-) or oxygen atom isoreactivity kind (oxidation kind) on the Si substrate, generate.This spike moves to SiO ₂On the interface of/Si substrate, on this interface, produce reaction, form SiO with the Si substrate ₂Film.As described above, in this formation method, by applying voltage, with O to the Si substrate ^-Oxidation such as ion or oxygen atom kind is directed to Si substrate surface (Si substrate and SiO ₂The interface of film) on.Therefore, forming SiO ₂After the film, the ion of above-mentioned oxidation kind or atomic group can be with Si substrate surface (Si substrate and SiO ₂The interface of film) Si oxidation forms SiO thus ₂Film.That is SiO, ₂The growth of film is not at SiO ₂The surface of film, but at Si substrate surface (Si substrate and SiO ₂The interface of film) produces.That is, in this formation method, be directed to Si substrate surface (Si substrate and SiO by ion or atomic group with the oxidation kind ₂The interface of film), thus at Si substrate surface (Si substrate and SiO ₂The interface of film) causes oxidation reaction on.

According to this kind mode, be on semiconductor surface (interface of semiconductor and chemical oxide film), to cause oxidation reaction in this formation method, different therewith is to be to cause oxidation reaction on the oxide-film surface in anode oxidation method.Therefore, in this formation method and the anode oxidation method, the growth site difference of chemical oxide film.That is, in anode oxidation method, the opposite side from the interface at substrate forms oxide-film, and different therewith is to be to form chemical oxide film from the interface in a general side in this formation method.That is, the interface of Si substrate and silicon dioxide film in silicon substrate one side shifting, remains cleaning along with oxidation reaction.Therefore, in this formation method, can obtain the good interface characteristic.

And then, in anode oxidation method, detach semiconductor composition after the oxidation from semiconductor surface, need this semiconductor composition is directed to the oxide-film surface, therefore, need high voltage.Different therewith is, in this formation method, chemical oxide film is (interface of semiconductor and chemical oxide film) growth on semiconductor surface, therefore, does not need to detach from semiconductor surface the ion of the semiconductor composition after the oxidation.Therefore, utilize this formation method, can under the voltage lower, form chemical oxide film than anode oxidation method.

In addition, open in the flat 3-6826 communique,, after the oxide-film that has formed porous matter, form oxide-film in order on the silicon substrate surface, to form oxide-film with low-voltage above-mentioned spy.That is, open in the flat 3-6826 communique, must form the oxide-film of porous matter above-mentioned spy.In addition, formed oxide-film is membranous also insufficient.

Different therewith is that the oxide-film that does not need to form this porous matter in this formation method just can form chemical oxide film on semiconductor surface.

In addition, in existing anode oxidation method, use porous matter silicon substrate in order under low-voltage, to carry out oxidation reaction.

Different therewith is, has used the strong oxidizing solution of oxidizing force or its steam in this formation method, therefore, might not use the treatment substrate (for example porous matter silicon substrate etc.) of porous matter.

Further describe voltage below by the manufacturing example and apply method, but the present invention is not limited thereto.

[making example 3]

The following describes and use nitric acid on silicon substrate 11, to utilize voltage to apply the example that method forms silicon dioxide film 41,42 as oxidizing solution.

After the n type silicon wafer of about 10 Ω cm, face orientation (100) with resistivity cleans with well-known RCA ablution, part on wafer surface is provided with the electrode of ohmic contact, and this wafer is impregnated into the nitric acid (HNO that concentration is 1 mole (mol./l) under room temperature (25 ℃) ₃) in the aqueous solution, and the platinum reference electrode of opposite electrode 15 between apply voltage from the variable voltage in 5～20V scope 14, on wafer surface, formed silicon dioxide (SiO ₂) film 41,42.

Figure 12 is that expression is to apply processing time that voltage is parameter (branch) and SiO ₂The SiO of the relation between the thickness (nm) of film 41,42 ₂Growth thickness-time response the figure of film 41,42.Applying under the situation that voltage is 5V, with respect to the processing time, SiO ₂The thickness of film is parabolic shape to be increased, and hence one can see that, SiO ₂The growth of film 41,42 is along with oxidation kind-be O ^-Or OH ^-Be diffusion control Deng anion or atomic group.In addition, applying under the situation that voltage is 10V, with respect to the processing time, SiO ₂The thickness of film 41,42 linearly increases, and hence one can see that is reaction control.That is, if apply the voltage height, then oxidation kind-O ^-Or OH ^-Deng anion or atomic group to SiO ₂Mobile the obtaining at/Si interface (interface of silicon dioxide film 41,42 and polysilicon 51) promotes that consequently, the oxidation reaction on this interface shows as control procedure.But, no matter under any situation, SiO ₂The growth of film 42 all is at SiO ₂The chemical oxide film of the oxidation reaction gained at/Si interface (surface of polysilicon 51).

Make example as can be known by this, processed substrate 2 is applied under the 10V voltage condition SiO being set at ₂The thickness and the time relation of film 41,42 become near linear relation, and therefore, increasing its time just is enough to form the SiO that thickness is 20～30nm ₂Film 41,42.

Figure 13 is at above-mentioned SiO ₂Aluminium electrode (grid 3) back that forms diameter on the film 41,42 and be 0.3nm obtains SiO by the above-mentioned voltage 5V, 60 minutes (processing time) of applying ₂Film is as A1/SiO ₂Current-voltage (IV) performance plot of the MOS diode under the situation of the thin-film transistor of/Si (100) structure (MOS diode (capacitor)).The SiO of this moment ₂The thickness of film 41,42 is at supposition SiO ₂The dielectric constant of film 41,42 is 3.9, utilizes capacitance-voltage (C-V) to be about 6.1nm when method is measured.In addition, above-mentioned SiO ₂Gate electrode on the film 41,42 apply on respectively 4V and-leakage current density during the voltage of 4V is respectively 8 * 10 ^-8A/cm ², 9 * 10 ^-9A/cm ²Though, be the SiO that forms at ambient temperature ₂Film 41,42 remains lower value.

Figure 14 is formed SiO when applying voltage and be respectively 5V, 10V, 15V and 20V ₂Film is with this SiO ₂Leakage current density in the thin-film transistor when electric field strength in the film is set at 5MV/cm and SiO ₂The relation of film thickness is surveyed and drawn the correlation diagram of gained randomly.In whole thickness scopes of being observed, its leakage current density all is 1 * 10 ^-7A/cm ²Below.

Figure 15 is the chloric acid (HClO excessively that possesses at 0.01 mole ₄) processed substrate 2 is applied 10 minutes formed SiO of 10V voltage in the aqueous solution ₂The I-V performance plot of the thin-film transistor of film 41,42 and C-V performance plot.To above-mentioned SiO ₂Gate electrode on the film 41,42 apply respectively 3V and-leakage current density during the voltage of 3V is respectively 7 * 10 ^-8A/cm ², 8 * 10 ^-9～8 * 10 ^-8A/cm ², in the C-V characteristic, have the sluggishness of about 0.9V.According to the SiO that x-ray photoelectron frequency spectrum (XPS:X-ray photoelectron spectrum) is measured and the C-V characteristic is tried to achieve ₂Thickness is 8.5nm (XPS) and 6.7nm (C-V).

More than be at HNO ₃The aqueous solution or HClO ₄The SiO that forms in the aqueous solution ₂Do not implement the result of gained under the situation of reprocessings such as annealing on the film 41,42.Forming SiO ₂After the film 41,42, it is implemented heat treatment (post-oxidation annealing handles hereinafter referred to as POA), the electrical characteristic that improved as follows in nitrogen.

Figure 16 and Figure 17 are at 0.01 mole of above-mentioned mistake chloric acid (HClO ₄) processed substrate 2 is applied 10 minutes formed SiO of 10V voltage in the aqueous solution ₂Film 41,42 (as shown in figure 15) carried out having formed after POA handles the I-V performance plot and the C-V performance plot of the thin-film transistor of aluminium electrode in 30 minutes with 200 ℃ of heating in nitrogen.Hence one can see that, to above-mentioned SiO ₂Gate electrode on the film 41,42 apply respectively 4V and-leakage current density during the voltage of 4V is respectively 1～8 * 10 ^-8A/cm ², 1～8 * 10 ^-9A/cm ², reduce to and implement about 1/5～1/10 of the preceding value of this heat treatment (POA processing).In addition, in the C-V characteristic, sluggishness becomes about 0.4V, reduces to only about half of by this heat treatment (POA processing).

And then, can confirm absorption (FT-IR) spectrum from fourier infrared to make SiO by the heat treatment under 200 ℃ ₂Hydrone in the film 41,42 spins off, and this shows, the raising of above-mentioned electrical characteristic is that the disengaging by the hydrone with trap energy level function realizes.

Measure the SiO that is tried to achieve by XPS ₂The thickness of film is 8.5nm, changes with not comparing before the heat treatment, but the SiO that is tried to achieve according to the C-V characteristic ₂The thickness of film is 7.6nm, than slightly increasing before the heat treatment.It has been generally acknowledged that this is because the hydrone that above-mentioned heat treatment causes breaks away from the cause that causes permitivity to descend.That is measure the SiO that is tried to achieve according to C-V characteristic and XPS before and after, comparative heat is handled ₂The dielectric constant of film 41,42, expectation are 4.9 (before handling) and 4.4 (handling the back), and its reason can think to exist in the film the bigger H of polarity before processing ₂O (hydrone) or OH ion thereby dielectric constant height, and after processing H ₂O breaks away from, and dielectric constant descends.

Figure 18 and Figure 19 are at the nitric acid (HNO at 1 mole ₃) apply the formed SiO of voltage with 20V in the aqueous solution ₂Film 41,42 is implemented C-V performance plot and the I-V performance plot that heat treated forms MOS diode gained afterwards thereon with 600 ℃ in nitrogen.Hence one can see that, and the sluggishness in the C-V characteristic reduces significantly, in addition, in the I-V characteristic, to electrode apply 10V and-leakage current density during 10V voltage is about 1 * 10 ^-5A/cm ²With 1 * 10 ^-6A/cm ²About.By in nitrogen, implementing heat treatment, SiO with 200 ℃ ₂H in the film 41,42 ₂O is purged, and the OH ion can't not removed at 500 ℃.Therefore, the raising of 600 ℃ of electrical characteristics that heat treated obtained is that removal by the OH ion realizes.

On the other hand, known OH ion is by handling with 200 ℃ POA in hydrogen atmosphere or heat treatment (post-metallization annealing after grid forms, handle hereinafter referred to as PMA) can be removed, therefore, in hydrogen atmosphere, implement above-mentioned heat treatment and can remove hydrone and OH ion effectively with 200 ℃.

In addition, also voltage discussed above can be applied method and 2 stage oxidizing process combines and forms grid oxidation film 4.For example, at least one operation in the enforcement 2 stage oxidizing process under applying the state of voltage.

As mentioned above, form in the operation (voltage applies method and 2 stage oxidizing process), processed substrate 2 is impregnated into forms grid oxidation film 4 (chemical oxide film) in the oxidizing solution at oxide-film.Therefore, even substrate surface has concavo-convex or curved surface, oxidizing solution also can spread all over the surface of processed substrate 2 equably.Thus, in spreading all over the whole zone that will form grid oxidation film 4, can both form the grid oxidation film 4 of uniform film thickness.Therefore, can produce possess high reliability, the thin-film transistor of high-quality grid oxidation film 4.

In thin-film transistor, grid oxidation film 4 membranous born the electrical characteristic that determines thin-film transistor and the important function of reliability.That is, in thin-film transistor, require to possess the performance (reliability, characteristic) that the grid oxidation film of insulating properties completely can directly have influence on the various devices that possess thin-film transistor, therefore, it possesses high-quality, high reliability special requirement.Therefore, utilize above-mentioned oxide-film to form operation and form grid oxidation film 4, just can form the high reliability of excellent such as insulation tolerance, high-quality grid oxidation film 4.Therefore, can realize the filming of grid oxidation film 4.Consequently, can produce the thin-film transistor thinner than existing thin-film transistor.

And then in said structure, heating or the electric active oxidation kind that is decomposed to form strong oxidizing force by oxidizing solution form chemical oxide film thus, therefore, for example also can form chemical oxide film under the temperature conditions below 200 ℃.Therefore, can produce and be applicable to the thin-film transistor of making LCD with flexible base, board (for example plastics, PETG (PET)).Thus, for example also can produce the plastic film transistor that hangs down threshold value on the plastic base.

Here, so-called " active oxidation kind " is meant and common oxygen (O ₂) compare the easier oxygen that causes chemical reaction.For example, be in the oxygen of state of atom, the oxonium ion (O of decomposition ^-), metastable oxygen (for example exciting common triplet oxygen and singlet oxygen of generating etc.), peroxide ion (O ₂ ^2-), superoxide ion (superoxide ion; O ₂ ^-), ozonide ion (O ₃ ^-), hydroxide ion (OH ^-), perhydroxy ion (OOH ^-), their atomic group.

In addition, so-called " oxidizing solution that contains the active oxidation kind " is meant the solution that contains above-mentioned active oxidation kind, so long as at least a solution gets final product among generating above-mentioned active oxidation kind, and not special the qualification.Preferably constitute: oxidizing solution, nitric acid, cross mixed solution, chloroazotic acid and the boiling water of mixed solution, sulfuric acid and nitric acid of mixed solution, ammoniacal liquor and hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of strong acid such as chloric acid, sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide by being selected from least a solution in the following solution or their mixed solution.In addition, the solution of the preferably not halogen-containing or metal of oxidizing solution.This is because halogen or metal are difficult to remove from the chemical oxide film that forms, and can cause membranous variation.Therefore, oxidizing solution nitric acid especially preferably.

In addition, the concentration of oxidizing solution be so long as can form the concentration of chemical oxide film and get final product on substrate, forms the easy degree (easily degree of oxidation) of chemical oxide film and different according to it.Concentration high oxidation power more is strong more, therefore, is being difficult to form under the chemical oxide film situation of (being difficult to oxidation), uses the oxidizing solution of high concentration.

In this manufacture method, the substrate that forms chemical oxide film preferably possesses at least a silicon compound of electing among monocrystalline silicon, polysilicon, amorphous silicon, discontinuous crystal grain border silicon metal, carborundum and the SiGe in its surface, by above-mentioned silicon compound direct oxidation is formed silicon oxide layer (silicon dioxide film).Silicon dioxide film can be as the dielectric oxide film of various uses such as grid oxidation film.Therefore, form operation and can form the high reliability that possesses good characteristics such as insulation tolerance, high-quality silicon dioxide film thin-film transistor by implementing above-mentioned oxide-film as chemical oxide film.

Polysilicon has and can use from the advantage of alignment method as grid material.Therefore, preferably use polysilicon as gate electrode.But,, then utilize the CVD method to be difficult to form uniform oxide-film if on substrate, utilize the CVD method to form polysilicon.Therefore, if do not form oxide-film with suitable thickness, the characteristic of the oxide-film that can't obtain to expect (for example suppressing leakage current etc.) just.Therefore, as long as can not form high-quality oxide-film, thin-film transistor just can't further be realized filming.Especially, the silicon that is layered on the substrate becomes polysilicon from monocrystalline silicon gradually.But polysilicon utilizes the CVD method to be layered on the substrate and forms.Therefore, the surface of formed polysilicon is concaveconvex shape.

In addition, thin-film transistor is the high performance thin film transistor that possesses the high-quality grid oxidation film of high reliability.In addition, this thin-film transistor also can be applied to the capacitor that uses in switch element for example or the memory cell.For example, can be applied to the pixel capacitor.Therefore, this thin-film transistor is applied to just can provide electric capacity and pixel stable display unit in the various displays such as liquid crystal display screen display, OLED display, flat-panel monitor.

In addition, the enforcement oxide-film in this manufacture method forms operation and also can be used as for example method of modifying of oxide-film.Particularly, existing grid oxidation film utilizes CVD method deposition or thermal oxidation method to form.But, utilize these methods can not be formed uniformly high-quality grid oxidation film.That is, existing grid oxidation film is uneven oxide-film.

Therefore, preferably implement voltage and apply method and/or 2 stage oxidative treatment at this uneven grid oxidation film.For example, utilizing after CVD method etc. forms grid oxidation film, preferably at least a method that applies in method and the 2 stage oxidizing process by voltage is handled this grid oxidation film.Thus, just can make and utilize the uneven grid oxidation film of formation such as CVD method to become even.That is, voltage can be applied method and 2 stage oxidizing process the membranous method of modifying that carries out the grid oxidation film of modification with the uneven grid oxidation film of opposing.

According to this kind mode, for example at the processing of implementing the oxide-film formation operation in this manufacture method with the uneven oxide-film of formation such as CVD method, it is even the thickness of uneven oxide-film can be become thus.Therefore, uneven oxide-film modification can be become the high oxide-film of reliability.

That is, common transistorized oxide-films such as TFT (for example grid oxidation film) utilize the CVD method to form.But the CVD method is the method for deposited oxide film on substrate, therefore, particularly can't form uniform grid oxidation film on the substrate with concavo-convex or curved surface.Therefore, the quality of present employed oxide-film is good inadequately.

Therefore, form operation, the substrate that has formed this inadequate oxide-film is impregnated in the solution that contains the active oxidation kind by implementing oxide-film.To implement the substrate direct oxidation by the hyperoxia voltinism solution of strong oxidizing force thus.Consequently, the thickness of oxide-film is become evenly, form the oxide-film of high reliability.

In addition, illustrated in the above description chemical oxide film is to require grid oxidation film high-quality, high reliability in order to obtain insulating properties, but the kind of chemical oxide film is not limited to this, but can be applied to use oxidizing solution to form in the oxide-film of any purposes of oxide.

In addition, form in the operation, can apply the size and the concentration of oxidizing solution, the processing time of this operation that apply voltage in method or the 2 stage oxidizing process and control the thickness of chemical oxide film by adjusting voltage at above-mentioned oxide-film.As mentioned above, form in the operation, can form high-quality chemical oxide film, therefore can realize the filming of chemical oxide film at oxide-film.Therefore, the driving voltage of thin-film transistor that possesses the chemical oxide film of filming also becomes lower.

[making example 4]

Here following two kinds of situations: as making shown in the example 1, the state heating (concentrating) in forming the aqueous solution of nitric acid that substrate that the 1st chemical oxide film (silicon dioxide film 41) will form silicon dioxide film 41 afterwards keeps being impregnated into 40% (wt) is to the situation (continuous oxidation) of azeotropic aqueous solution of nitric acid to form the 2nd chemical oxide film (silicon dioxide film 42); The aqueous solution of nitric acid and the azeotropic aqueous solution of nitric acid of 40% (wt) are set respectively, form the substrate that the 1st chemical oxide film (silicon dioxide film 41) will form silicon dioxide film 41 afterwards at the aqueous solution of nitric acid that uses 40% (wt) and be impregnated into the situation (discontinuous oxidation) to form the 2nd chemical oxide film (silicon dioxide film 42) in the azeotropic aqueous solution of nitric acid.

Particularly, in continuous oxidation, at first will in the nitric acid of 40wt%, flood 10 minutes through the substrate that RCA cleans., this substrate kept impregnation state, nitric acid is heated to the azeotropic state thereafter.Then, become azeotropic nitric acid after, continued dipping 2 hours.

On the other hand, in discontinuous oxidation, at first will in the nitric acid of 40wt%, flood 10 minutes through the substrate that RCA cleans.Then, substrate is taken out from the nitric acid of 40wt%, clean back was flooded 2 hours in azeotropic nitric acid.

To compare discovery according to the silicon dioxide film that this kind mode forms, as shown in figure 30, in continuous oxidation, form the silicon dioxide film about thicker 4nm, in discontinuous oxidation, then form the silicon dioxide film that has only about 1nm.

In addition, as shown in figure 29, in the oxidation of the continuous TFT polysilicon membrane of oxidation, compare, can in the shorter time, form thick chemical oxide film with the situation of discontinuous oxidation.

The present invention is not limited to above-mentioned execution mode, can do various changes in scope shown in the claim, and the execution mode of disclosed respectively technical approach appropriate combination gained in the different execution modes is also contained in the technical scope of the present invention.

[the 2nd execution mode]

According to Figure 21 to Figure 28, be described as follows at an embodiment of the invention.The manufacture method of the mos capacitance device that has constituted to have formed silicon dioxide film and electrode on silicon substrate is that example describes below.In addition, the present invention is not limited thereto.

The manufacture method of the mos capacitance device (semiconductor device) in the present embodiment is characterised in that it possesses oxide-film and forms operation, makes the different oxidizing solution of concentration touch semiconductor surface, forms chemical oxide film thus on semiconductor surface by stages.The following describes the semi-conductive manufacturing installation that distinctive oxide-film forms operation and implements this operation among the present invention.

Figure 21 is a summary section of going up the major part of employed manufacturing installation in the method that forms silicon dioxide film in the 2nd execution mode of the present invention at silicon substrate (semiconductor), its structure is, the silicon substrate 10 of processed usefulness is impregnated into the oxidizing solution 30 of the low concentration in first treatment trough 20, thus after forming first oxide-film (the 1st chemical oxide film) 40 on silicon substrate 10 surfaces, the silicon substrate 10 that has formed the processed usefulness of the 1st oxide-film 40 is impregnated in the oxidizing solution 60 of the high concentration in second treatment trough 50, on the 1st oxide-film 40, forms second oxide-film (the 2nd chemical oxide film thus; Not shown), finally can form the silicon dioxide film 70 that constitutes by the 1st oxide-film 40 and the 2nd oxide-film.That is, this manufacturing installation has constituted the oxide-film formation portion of formation method that is used for implementing oxide-film of the present invention of explanation in the back.

Figure 22 (a)～Figure 22 (f) thus be to disclose to utilize above-mentioned manufacturing installation shown in Figure 9 on silicon substrate 111, to form the process flow profile that silicon dioxide film 116 and electrode 118 produce the method for mos capacitance device, the following describes an embodiment of the invention.

At first, shown in Figure 22 (a), on silicon substrate 111, be pre-formed separated region 112.Here, using resistivity on the silicon substrate 111 is the P type substrate of 10～15 Ω cm, face orientation (100).In addition, on this silicon substrate 111, inject after boron (B) blocks as raceway groove, on a face of silicon substrate 111, form and utilize LOCOS (local oxidation of silicon: local oxidation of silicon) the produced thickness of technology is about the silicon dioxide film of 500nm as separated region 112.This separated region 112 is not limited to LOCOS, also can form Embedded silicon dioxide film on silicon substrate.In addition, silicon substrate 111 is not limited to above-mentioned characteristic.In addition, in Figure 22 (a), the zone that has formed natural oxide film 113 is the zone that will form silicon dioxide film 116 in operation shown below, is expressed as active region 114.In addition, the silicon substrate among Fig. 91 is to have represented to comprise on the silicon substrate 111 shown in Figure 22 (b) formed separated region (locos oxide film) for convenience's sake in interior integral body.

Shown in Figure 22 (a), in this process, when having formed natural oxide film 113 on the surface of silicon substrate 111, utilize well-known RCA ablution promptly to utilize after ammoniacal liquor-hydrogen peroxide cleaning, in concentration is 0.5% (Capacity Ratio, below note is vol.) dilute hydrofluoric acid solution in about 5 minutes of dipping so that as Figure 22 (b), remove natural oxide film 113 fully.That is, the active region 114 of silicon substrate 111 reveals.

Then, utilize ultra-pure water that silicon substrate 111 rinsings were handled (cleaning) after 5 minutes, silicon substrate 111 is impregnated in the oxidizing solution 30 of the low concentration that holds in first treatment trough 2 shown in Figure 9.Thus, shown in Figure 22 (c), in active region 114, formed the 1st oxide-film (the 1st chemical oxide film).In addition, the dip time here is decided to be 10 minutes.According to this kind mode, the surface was flooded 10 minutes in the oxidizing solution 30 of low concentration through the silicon substrate 111 after clean the processing, formed first oxide-film 115 shown in Figure 22 (c).In addition, the 1st oxide-film 115 is silicon substrate 111 silicon dioxide films after oxidized.

In addition, the oxidizing solution 30 of low concentration is that concentration is low and solution (oxidizing solution) that oxidizing force is strong.Here, the oxidizing solution working concentration is the aqueous solution of nitric acid of 40% (weight ratio, below note is done " wt ").In addition, the thickness of the 1st oxide-film 115 is decided to be 1.1nm

In the oxidizing solution 60 of the high concentration that holds in then, being impregnated into the silicon substrate 111 that has formed the 1st oxide-film 115 in second processing layer shown in Figure 9.Thus, shown in Figure 22 (d), the oxidation reaction of silicon substrate 111 is further carried out, and has further formed the 2nd oxide-film (not shown) at the 1st oxide-film 115, becomes silicon dioxide film 116.That is, silicon dioxide film 116 be by formed the 1st oxide-film 115 in the operation of Figure 22 (c) and in the operation of Figure 22 (d) formed the 2nd oxide-film (not shown) constitute.That is, silicon dioxide film 116 is to be made of the 1st oxide-film 115 and the 2nd oxide-film from see in form, but because two parts all are silicon dioxide, therefore is actually the silicon dioxide film 116 of individual layer.In addition, the dip time here is decided to be 10 minutes.According to this kind mode, flooded 10 minutes in the oxidizing solution 60 of high concentration having formed the 1st oxide-film 115 silicon substrate 111 afterwards, be formed uniformly the silicon dioxide film 116 shown in Figure 22 (d).Here, silicon dioxide film 116 thickness are decided to be 10nm.

In addition, the oxidizing solution 60 of high concentration is concentration height and the strong solution (oxidizing solution) of oxidizing force.Here, working concentration is the oxidizing solution of the azeotropic nitric acid of 68% (wt) as high concentration.

Then, shown in Figure 22 (e), on silicon dioxide film 116 and separated region 112, form metal film (film that contains metal) 117.Here, this metal film 117 is that the aluminium alloy of the silicon by will containing 1 percentage by weight forms (following this metal film electrode simply is called the A1 electrode) by the thickness that known resist heating vapour deposition method is deposited as about 200nm.In addition, metal film 117 is not limited to the A1 electrode, also can use polysilicon electrode (material) to replace this metal film 117 by for example adhering to.

As Figure 22 (f) shown in, with metal film 117 wiring pattern formation electrode 118 with reservation shape, thus can produce mos capacitance device thereafter.

As shown in figure 23, has stable capacitance (electrostatic capacitance) according to the produced mos capacitance device of this kind mode (semiconductor device).Figure 23 be the electrostatic capacitance (C) of the mos capacitance device that generates in the present embodiment with the relation that applies voltage (V), be the C-V performance plot.By this performance plot as can be known, on electrode 118, apply positive voltage, on the interface (silicon substrate surface) of silicon substrate 111 and silicon dioxide film (with the interface (semiconductor surface) of oxide-film), bring out inversion layer thus, obtain stable capacitance (electrostatic capacitance).

According to this kind mode, in the present embodiment, silicon substrate 111 is impregnated in the different aqueous solution of nitric acid of concentration, on silicon substrate 111, form silicon dioxide film 15 by 2 stages.That is to say, formed the silicon dioxide film 116 that is used for constituting the mos capacitance device by means of following operation: making concentration is that the aqueous solution of nitric acid (oxidizing solution of the 1st concentration) of 40% (wt) touches silicon substrate 111 so that form the operation of the 1st oxide-film (the 1st chemical oxide film) 15 on silicon substrate 111 surfaces; And make that used concentration is the high concentration aqueous solution of nitric acid (oxidizing solution of the 2nd concentration of 40% (wt) when forming the 1st oxide-film 115, the aqueous solution of nitric acid of above-mentioned 68% (wt)) touches the 1st oxide-film 115, so that on the 1st oxide-film 115, form the operation of the 2nd oxide-film.

In addition, C-V performance plot according to Figure 23 also can be understood, the leakage current density of the above-mentioned mos capacitance device that forms according to this kind mode also is equal to or higher than the leakage current density characteristic of the mos capacitance device that silicon dioxide film that use forms with common high-temperature thermal oxidation method forms as dielectric film, and its high-performance is positively approved.

In addition, in above-mentioned manufacturing example, the thickness of silicon dioxide film 116 is decided to be 10nm, but this thickness there is no specific restriction.By adjusting the time in the oxidizing solution 60 that silicon substrate 111 is immersed in the oxidizing solution 30 of low concentration and high concentration, the thickness of the 1st oxide-film 115 and silicon dioxide film 15 will change.In other words, the time that is impregnated in the oxidizing solution according to the thickness setting silicon substrate of expecting 111 gets final product.In addition, the oxide-film formation speed of the 1st oxide-film 115 grades also can change along with the concentration difference of oxidizing solution.Therefore, dip time gets final product according to the kind/concentration of oxidizing solution, the thickness setting of formation oxide-film, does not have specific restriction.

In addition, in the present embodiment, the oxidizing solution of low concentration or oxidizing gas are that the aqueous solution of nitric acid of 40% (wt) is that example is illustrated with concentration, also can replace and use at least a aqueous solution that is selected from following group: the mixed solution and the chloroazotic acid of mixed solution, sulfuric acid and the nitric acid of mixed solution, ammoniacal liquor and the hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of mistake chloric acid, sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide, and then also can use boiling water with oxidizing force.

In addition, in the present embodiment, using concentration of nitric acid is oxidizing solution or the oxidizing gas of the aqueous solution of nitric acid (so-called azeotropic nitric acid) of 68% (wt) as high concentration, also can replace use and cross at least a aqueous solution of selecting chloric acid, azeotropic sulfuric acid and the chloroazotic acid from azeotropic.

In addition, if make the oxidizing solution of the azeotropic mixture of water as high concentration, then have fixing concentration respectively in this solution and steam (being gas) the chemical oxide film forming process on semiconductor, can control the growth of chemical oxide film by time management.Therefore, the oxidizing solution of high concentration azeotropic mixture preferably.

In addition, shown in the execution mode, utilize the 1st chemical oxide film (the 1st oxide-film 115) of the oxidizing solution formation of low concentration preferably to have hole as described later.That is the 1st chemical oxide film lower film of atomic density preferably.Thus, just can carry out smoothly by means of the formation of the 2nd chemical oxide film of the oxidizing solution of high concentration.This is because the effect (contact) owing to oxidizing solution in the hole in the 1st chemical oxide film has formed the 2nd chemical oxide film.That is, the 1st chemical oxide film that contains the low atomic density of hole becomes catalyst, and the film formed oxidation reaction of the 2nd chemical oxidation is carried out successively, therefore, can form more high-quality chemical oxide film.

In addition, in the above description, as shown in Figure 9, by means of oxidizing solution 60 (oxidizing solutions of 2 kinds of concentration) the formation chemical oxide film of oxidizing solution 30 that is contained in the low concentration in the 1st treatment trough 20 and the 2nd treatment trough 50 respectively and high concentration.But the formation method of chemical oxide film is not limited to this, also can be for example to divide a plurality of stages (preparing concentration is different more than 2 kinds oxidizing solution or its gas) to switch to high concentration successively from above-mentioned low concentration.In addition, the concentration of oxidizing solution is risen from low to high continuously.That is, also low concentration solution can be concentrated, transition is a highly concentrated solution continuously.For example, the oxidizing solution (oxidizing solution of low concentration) that will be lower than azeotropic concentration is heated to azeotropic concentration and concentrates, and keeps this heated condition, and thus, the oxidizing solution that reaches azeotropic concentration has just formed fixing solution composition, steam is formed.Thus, just can control the growth of chemical oxide film by time management.Therefore, can be with the formation (thickness and quality) of higher precision control chemical oxide film.

In addition, the oxidizing solution of above-mentioned low concentration and the high concentration oxidation kind that preferably oxidizing force is strong (for example oxonium ion or atomic groups such as oxonium ion, hydroxide ion, peroxide ion.Thus, just can form chemical oxide film below 200 ℃.Therefore, also can be applied to the formation of TFT in need manufacture process in the LCD of the flexibility that forms chemical oxide film below 200 ℃.

In the present embodiment, at above-mentioned silicon dioxide film 116, can be formed in the nitrogenous gas, especially make the part on surface be converted into the silicon dioxide film that contains silicon nitride after the silicon nitride, perhaps utilize CVD method etc. on the film that contains silicon nitride behind the above-mentioned nitrogen treatment, to overlap to form thick SiO by plasma nitridation process ₂Deng dielectric film.

The nitrogenize chemical oxide film has and its composition character between oxide-film and nitride film accordingly basically.For example, compare with oxide-film, the diffusion coefficient of the impurity in the nitride film less (hot nitrogenize), therefore, excellent performance aspect the diffusion of impurity (particularly boron) in the Si substrate that the nitrogenize chemical oxide film mixes in stoping grid.Therefore, the nitrogenize chemical oxide film can be applied in the semiconductor device of gate insulating film (for example 4nm is following) that need be as thin as a wafer.

According to this kind mode, nitrogen treatment is a kind of method that improves transistor performance, can further improve the membranous of chemical oxide film by means of this nitrogen treatment.Therefore, can realize the filming of chemical oxide film.

In addition, so-called " carrying out nitrogen treatment " is that at least a portion of formed silicon dioxide film 116 (chemical oxide film) is carried out nitrogenize.That is, nitrogen treatment is, to heat in the gas atmosphere that contains the nitrogenize kind after forming chemical oxide film in the oxidation that utilizes semiconductor surface, thus at least a portion of chemical oxide film is carried out the processing of nitrogenize.

Nitrogen treatment can be ammoniacal liquor (NH ₃) nitrogenize, nitrous acid (N ₂O) nitrogenize, nitric oxide (NO) nitrogenize etc.In these methods, the nitrogenize kind is ammoniacal liquor, nitrous acid, nitric oxide.In addition, the nitrogenize chemical oxide film by NO nitrogenize gained can not reduce performance, and performance is excellent aspect life-span of the insulation breakdown tolerance level of gate insulating film, hot carrier tolerance level.

Other examples of present embodiment are at above-mentioned silicon dioxide (SiO ₂) composite membrane that forms of stacked high dielectric film on the film 116-for example hafnium oxide, aluminium oxide etc., can be used in the gate insulating film of MOS transistor thus.In the case, compare, can realize that the performance of transistor characteristic improves (improving mobility etc. by reducing leakage current, reduction interface energy level etc.) with the situation of only using high dielectric film.The silicon dioxide film that forms below above-mentioned high dielectric film can be 1nm or be lower than the film as thin as a wafer of 1nm for example.In addition, utilize silicon dioxide film that common thermal oxidation method forms if about 1nm, then leakage current or interface energy level are very big and be not enough to practicality, but the silicon dioxide (SiO of present embodiment ₂) film 116 also goes for forming the composite membrane of the stepped construction of thick insulating film thereon.And then, be not only above-mentioned high dielectric film, the oxide-film of present embodiment also can be applied to ferroelectric thin film is stacked and in the structure that forms.

In addition, metal film 117 (metallic film) has used aluminium in the above description, but the film that contains metallic atom can be the film that contains the metallic atom of electing among aluminium, magnesium, nickel, chromium, platinum, palladium, tungsten, titanium and the tantalum.In addition, the film that contains metallic atom preferably contains the film of reactive metal atom, for example, and preferably metal film or siliceous aluminum films such as aluminium, magnesium, nickel.In addition, the film that contains metallic atom also can use compounds such as titanium nitride or tantalum pentoxide.

In addition, Shuo Ming the silicon substrate that is to use monocrystalline silicon 111 is made the example of mos capacitance device as processed substrate in the present embodiment, each operation as described herein also is applicable to and is forming polycrystalline (comprising crystallite) silicon or amorphous silicon on the glass substrate or on the substrate such as PET, thereby forms the situation of thin-film transistor (TFT).That is, the semiconductor that form chemical oxide film preferably contains silicon and the chemical oxide film that will form is a silicon dioxide film.

In addition, above-mentioned monocrystalline silicon substrate is not limited to flat shape, in 3D shape or have on the substrate of the concavo-convex or curved surface of sphere, concavo-convex or curved surface area is as transistorized raceway groove with it, also can be at low temperatures be formed uniformly the dielectric films such as silicon dioxide film described in the present embodiment at this on the concavo-convex or curved surface.

And then, above-mentioned each operation is not limited to make the situation of mos capacitance device, also can be applied in gate insulating film to use the MOS transistor of dielectric films such as this silicon dioxide film, and then also can be applied in the manufacture process of capacitor insulating film of memories such as large scale integrated circuit (LSI), for example flash memory.

In addition, in the above description, formed silicon dioxide film, but chemical oxide film along with changing, oxidized semi-conductive kind is not limited to silicon dioxide film as chemical oxide film.

In addition, in the above description, on silicon substrate 111, do not apply voltage; Form silicon dioxide film by applying voltage, just can accelerating oxidation the carrying out (can improve the formation speed of silicon dioxide film) of reaction.

In addition, in the above description, silicon substrate 111 is immersed in the oxidizing solution 30,60 of low concentration and high concentration.Therefore, can form oxide-film with very simple structure.But, might not flood silicon substrate 111, as long as make oxidizing solution generation effect on silicon substrate.For example, can adopt in the steam (oxidizing gas) of the oxidizing solution that is exposed to low concentration or high concentration.In this case, use the steam of above-mentioned oxidizing solution to get final product.

Further describe the present invention below by embodiment, but the present invention is not limited thereto.

[embodiment 1]

The method formation thickness that describes below with 2 stages solution oxides formation chemical oxide film is the SiO of 3.5nm ₂The situation of film.

At first, in order to form the 1st chemical oxide film (the 1st oxide-film 115), silicon substrate 111 is impregnated in the aqueous solution of nitric acid of 40% (wt) under the state that does not apply voltage, and having formed thickness is that atomic density 1.1nm, porous, that atomic density is relatively low is 2.22 * 10 ²²Atom/cm ³SiO ₂Film (the 1st oxide-film 115; Chemical oxide film).

Then,, be impregnated in the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of concentration of nitric acid 68% (wt) in order to form the 2nd chemical oxide film, formed than the 1st chemical oxidation thickness, atomic density is 2.34 * 10 ²²Atom/cm ³SiO ₂Film (whole thickness is 3.5nm).

Can think, in the above-mentioned the 1st and the 2nd oxidizing process (the formation operation of the 1st and the 2nd chemical oxide film), the SiO of the 1st chemical oxide film that in the aqueous solution of nitric acid of initial 40% (wt), forms ₂Existing hole becomes the place that nitric acid decomposes in the film,, contains the above-mentioned SiO of the low atomic density of this hole that is ₂Film (the 1st chemical oxide film 115) becomes catalyst, and the nitric acid oxidation that forms the 2nd chemical oxide film carries out successively.

Figure 24 represents formed SiO in the nitric acid oxidation process in above-mentioned 2 stages ₂The XPS spectral characteristic figure of film 116 (chemical oxide film), 2 sharp-pointed peak values are to be formed by the photoelectron that discharges at Si (2p) track that sends from silicon substrate, the peak value of amplitude broad is by from above-mentioned SiO ₂The photoelectron that film 116 discharges forms.Areal intensity ratio according to these peak values can be obtained above-mentioned SiO ₂The whole thickness of film 116 is 3.5nm.

Relative therewith, if do not form the 1st chemical oxide film, from just begin at first with the same formation condition of above-mentioned the 2nd chemical oxide film under silicon substrate is impregnated into the azeotropic aqueous solution of nitric acid that concentration of nitric acid is 68% (wt), determining to form does not have the very high SiO of hole, atomic density ₂Film, thickness also can hang down and reach 1.4nm.

Figure 25 is that to have the thickness that is obtained in the nitric acid oxidation process in above-mentioned 2 stages be the SiO of 3.5nm ₂The I-V performance plot of the MOS structure diode of film 116 before and after PMA handles.This expression is implemented PMA with 250 ℃ and is handled in hydrogen atmosphere under the state of MOS structure diode, thus, the leakage current density when forward bias 1V and reverse bias-1V becomes 1 * 10 respectively ^-4A/cm ²With 2 * 10 ^-6A/cm ², be respectively 1 * 10 before handling with PMA ^-3A/cm ²With 7 * 10 ^-4A/cm ²Compare, leakage current density has positively reduced.

Figure 26 is that to have the thickness that is obtained in the nitric acid oxidation process in above-mentioned 2 stages be the SiO of 3.5nm ₂The C-V performance plot of the MOS structure diode of film 116 before PMA handles.In this C-V performance plot, can observe the knurl (expansion of characteristic is heaved) that interface energy level causes, also exist sluggishness simultaneously.By this diode is directly carried out heat treated with 250 ℃ in hydrogen atmosphere, promptly implement so-called PMA and handle, just can eliminate above-mentioned knurl fully, and sluggishness disappears substantially also.

In this embodiment, at thickness be the SiO of 3.5nm ₂ Form A1 electrode 17 on the film 116, then,, eliminate interface energy level or SiO by in hydrogen atmosphere, handling with 250 ℃ of PMA that heat ₂In between gap level, and then by increasing SiO ₂The band gap of film 116 significantly reduces leakage current density, can improve the performance of dielectric film; But be not limited to this example, rule of thumb, by prolonging the dip time in aqueous solution of nitric acid, SiO ₂The thickness of film 116 can be increased to tens of nm, and, be selected in the hundreds of ℃ of appropriate values about (for example 450 ℃) by above-mentioned PMA is handled, just can improve the electrical characteristic of MOS structure, particularly can realize the elimination, the reduction of leakage current density of sluggishness, the raising that insulation breakdown is withstand voltage.

What Figure 27 represented is in order to form the 1st chemical oxide film silicon substrate 111 to be impregnated under the state that does not apply voltage in the aqueous solution of nitric acid of 40% (wt), and having formed thickness is that atomic density 1.1nm, porous, that atomic density is relatively low is 2.22 * 10 ²²Atom/cm ³SiO ₂Film (the 1st chemical oxide film) then is immersed in the SiO that forms in the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of concentration of nitric acid 68% (wt) afterwards in order to form the 2nd chemical oxide film ₂The relation of the thickness of film 116.Hence one can see that, SiO ₂The thickness of film 116 is along with almost orthoscopic increase of dip time, and can form thickness is the above SiO of 10nm ₂Film 116.

In addition, above-mentioned 2 stage nitric acid oxidation processes will be except will being divided into the switching of 2 stages the stage from the low concentration to the high concentration, the multistage that embodiments of the present invention also comprise from the low concentration to the high concentration switches successively or switches continuously from the low concentration to the high concentration, for example, keeping being immersed in the state that seethes with excitement in the aqueous solution of nitric acid of 40% (wt) is the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of 68% (wt) up to concentration of nitric acid.That is, the oxidation in the present embodiment both can be the continuous oxidation in the 1st execution mode, also can be discontinuous oxidation.

[the 3rd execution mode]

Below, the 3rd execution mode of the present invention is described.Utilizing the polysilicon on the substrate to form under the situation of TFT, in its gate insulating film, use stacked silicon dioxide film (SiO ₂).Therefore, the example of being narrated (embodiment 2) forms silicon dioxide film on the polysilicon on substrate (being that silicon substrate 111 is polycrystalline silicon substrates) similarly here, produces mos capacitance device (its capacitor insulating film) thus.

In this case, can form silicon dioxide (SiO by the nitric acid oxidation process in 2 stages on the polysilicon surface on the substrate ₂) film.

Identical with above-mentioned [the 2nd execution mode (embodiment 1)] (with reference to Figure 22 (a)～Figure 22 (f)), at first in order to form the 1st chemical oxide film, polysilicon layer on the substrate is impregnated under the state that does not apply voltage in the aqueous solution of nitric acid of 40% (wt) (making its contact), having formed thickness is the SiO of 1.1nm ₂Film (chemical oxide film) (Figure 22 (c)).

Then, in order to form the 2nd chemical oxide film, will have above-mentioned the 1st chemical oxide film (SiO ₂Film) polysilicon layer on the substrate is impregnated into the concentration of nitric acid that (make its contact) be in fluidized state under the state that does not apply voltage be the azeotropic aqueous solution of nitric acid (boiling point is 120.7 ℃) of 68% (wt), generates the 2nd thicker chemical oxide film (SiO ₂), be formed uniformly the SiO that whole thickness is about 25nm thus ₂Film 116 (chemical oxide film) (Figure 22 (d)).

In this case, identical with the 1st execution mode (embodiment 1), by forming each oxidizing process of the above-mentioned the 1st and the 2nd chemical oxide film, the SiO of the 1st chemical oxide film that in the aqueous solution of nitric acid of initial 40% (wt), forms ₂Existing hole becomes the place that nitric acid decomposes in the film, that is, the atomic density of porous is relatively low, and (atomic density is 2.22 * 10 ²²Atom/cm ³About) the SiO of above-mentioned the 1st chemical oxide film ₂Film becomes catalyst, and the nitric acid oxidation that forms the 2nd chemical oxide film carries out successively, and the density that has generated ratio the 1st chemical oxide film is high slightly, and (atomic density is 2.34 * 10 ²²Atom/cm ³About) and than the 1st chemical oxide film thicker the 2nd chemical oxide film (SiO ₂Film).

Then, at this silicon dioxide film (chemical oxidation SiO ₂Film) goes up formation metal film (A1 electrode) 118.This A1 electrode 118 is that the aluminium alloy by the silicon that will contain 1% (wt) forms (Figure 22 (e)) by the thickness that known resist heating vapour deposition method is deposited as about 200nm.Also can use the polysilicon electrode material to replace this A1 electrode 118 by for example adhering to.

Thereafter, the wiring pattern formation A1 electrode with reservation shape produces mos capacitance device (Figure 22 (f)) thus.

Every characteristic of the mos capacitance device that is obtained in the present embodiment each all the 1st execution mode (embodiment 1) with above-mentioned is identical, present high-performance, high stability.

In addition, what this example was narrated is to use aqueous solution of nitric acid as oxidizing solution, also can replace to use at least a aqueous solution that is selected from following group: mixture-aqueous sulfuric acid, chloroazotic acid and their mixed solution (comprising azeotropic mixture) of crossing mixture-mistake chloric acid aqueous solution, sulfuric acid and the water of chloric acid and water.

In addition, in the present embodiment, also can use by nitrogen treatment above-mentioned silicon dioxide film 116 (chemical oxide films; SiO ₂Film) a part is converted into the composite membrane after the silicon nitride film that thickness is 0.3～0.5nm.

In addition, explanation is the example of mos capacitance device in the present embodiment, under the situation of the gate insulating film that forms thin-film transistor (TFT), by in the middle of this stacked silicon dioxide film or stacked silicon dioxide film, inserting the film that contains silicon nitride, the few high performance dielectric film of interface energy level be can obtain, large scale integrated circuit (LSI) or charge-coupled device (CCD) etc. for example can be used for.In addition, also can be used for using polysilicon and the capacitor insulating film of memories such as the interlayer dielectric of the Miltilayer wiring structure that forms or flash memory, believe in these fields and can be widely used in wiring.

In addition, the polycrystalline silicon substrate that is to use of explanation is made the example of mos capacitance device as silicon substrate 111 in the present embodiment, each operation as described herein is not limited to use the situation of monocrystalline silicon substrate, certainly also be applicable to utilize on the glass substrate or substrate such as PET on polycrystalline (comprising crystallite) silicon or the amorphous silicon situation that forms thin-film transistor (TFT).Especially, in the present embodiment, owing to can form chemical oxide film below 200 ℃, therefore, also be applicable to the formation of the TFT in the manufacture process of the LCD of flexibility.

And then above-mentioned each operation is not limited to make the situation of mos capacitance device, also can be applied to use to possess be layered in formed silicon dioxide film or the formed SiO of the stacked CVD of utilization method in the present embodiment thereon on gate insulating film ₂The stacked silicon dioxide film of film or in the middle of above-mentioned stacked silicon dioxide film, insert any one the gate insulating film of MOS transistor, large scale integrated circuit (LSI) and charge-coupled device (CCD) etc. or interlayer dielectric etc. of the multilayer film of the film contain silicon nitride.

In the present embodiment, except the formation of above-mentioned silicon dioxide film 15, also the nitrogen treatment that can form in processing or the nitrogen plasma by the film that its surface is contained silicon nitride forms the film that contains silicon nitride on above-mentioned silicon dioxide film 15 surfaces, and then, also can be on above-mentioned silicon dioxide film 15 or overlap above the above-mentioned film that contains silicon nitride and utilize CVD method etc. to form thick SiO ₂Deng dielectric film.

In addition, explanation is to use the example of being made the mos capacitance device by the silicon substrate 111 of polysilicon process as processed substrate in the present embodiment, but each operation as described herein also is applicable to the situation of using monocrystalline silicon substrate certainly, also go for utilizing on the glass substrate or substrate such as PET on polycrystalline (comprising crystallite) silicon or the situation that forms thin-film transistor (TFT) such as amorphous silicon, carborundum, SiGe.

The present invention is not limited to above-mentioned execution mode, can do various changes in scope shown in the technical scheme, and the execution mode of disclosed technical approach appropriate combination gained in the different execution modes is also contained in the technical scope of the present invention.For example, the oxidation of recording and narrating in the 2nd and the 3rd execution mode can be continuous oxidation or the discontinuous oxidation in the 1st execution mode.

In addition, embodiment that in the preferred implementation that carries out an invention, provides or embodiment, only in order to show technology contents of the present invention, can not be confined to such concrete example and do the explanation of narrow sense, in the scope of spirit of the present invention and following claims, can make various changes back and implement.

As mentioned above, method of manufacturing thin film transistor of the present invention has oxide-film and forms operation, the substrate that its surface will be formed chemical oxide film is impregnated in the oxidizing solution that contains the active oxidation kind, makes the aforesaid substrate direct oxidation, forms chemical oxide film thus.Therefore, spreading all over the chemical oxide film that can both form uniform film thickness on the whole zone that will form chemical oxide film.Therefore, can produce possess high reliability, the thin-film transistor of high-quality chemical oxide film.

Therefore, by means of the present invention, can under the low temperature below 200 ℃, produce the thin-film transistor that possesses high-quality chemical oxide films such as grid oxidation film, therefore, can be applied to make flexible liquid crystal display with the flexible base, board (for example plastics, PETG (PET)) that possesses low melting point substrates such as PET or IC etc., can be applied to widely in the electricapparatus industry.

In addition,, can at low temperatures high-quality chemical oxide film be formed the coverlay of expection thickness, and can produce the semiconductor device that possesses this chemical oxide film, therefore, can be applied to widely in the electricapparatus industry by means of the present invention.

Claims (40)

1. a method of manufacturing thin film transistor that possesses oxide-film is characterized in that having: oxide-film formation operation, the substrate that the surface will be formed chemical oxide film is impregnated in the oxidizing solution that contains the active oxidation kind, make the aforesaid substrate direct oxidation, form chemical oxide film thus

Form operation at above-mentioned oxide-film, aforesaid substrate is impregnated in the different above-mentioned oxidizing solution of concentration, and makes above-mentioned oxidizing solution become high concentration oxygen voltinism solution from low concentration oxygen voltinism solution.

2. method of manufacturing thin film transistor as claimed in claim 1 is characterized in that the concentration of above-mentioned low concentration oxidizing solution is lower than azeotropic concentration, and the concentration of above-mentioned high concentration oxidizing solution is more than or equal to azeotropic concentration.

3. method of manufacturing thin film transistor as claimed in claim 1 is characterized in that, above-mentioned oxide-film form operation with above-mentioned low concentration oxygen voltinism solution concentration after as above-mentioned high concentration oxidizing solution.

4. method of manufacturing thin film transistor as claimed in claim 1 is characterized in that, above-mentioned oxide-film forms operation and undertaken by apply voltage on the above-mentioned substrate that will form chemical oxide film, makes the chemical oxide film growth thus on the aforesaid substrate surface.

5. method of manufacturing thin film transistor as claimed in claim 1 or 2, it is characterized in that the above-mentioned substrate that will form chemical oxide film possesses from the teeth outwards and is selected from least a in monocrystalline silicon, polysilicon, amorphous silicon, discontinuous crystal grain border silicon metal, carborundum and the SiGe.

6. method of manufacturing thin film transistor as claimed in claim 1 or 2, it is characterized in that above-mentioned oxidizing solution comprises: be selected from nitric acid, cross chloric acid, at least a solution in the group of mixed solution, chloroazotic acid and the boiling water of mixed solution, sulfuric acid and the nitric acid of mixed solution, ammoniacal liquor and the hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide or their mixed solution.

7. method of manufacturing thin film transistor as claimed in claim 6 is characterized in that above-mentioned oxidizing solution is an azeotropic mixture.

8. method of manufacturing thin film transistor as claimed in claim 7, it is characterized in that above-mentioned oxidizing solution comprises: be selected from as with the azeotropic nitric acid of the azeotropic mixture of water, as with the azeotropic sulfuric acid of the azeotropic mixture of water and as crossing at least a solution in the group of chloric acid with the azeotropic of the azeotropic mixture of water.

9. method of manufacturing thin film transistor as claimed in claim 1 or 2 is characterized in that, above-mentioned oxide-film forms operation and carries out under the temperature below 200 ℃.

10. method of manufacturing thin film transistor as claimed in claim 1 or 2 is characterized in that having: the operation that further forms dielectric film after forming above-mentioned chemical oxide film on this chemical oxide film.

11. method of manufacturing thin film transistor as claimed in claim 1 or 2 is characterized in that, above-mentioned oxide-film forms operation and comprises following operation:

Substrate is impregnated in the oxidizing solution that is lower than azeotropic concentration, forms the 1st oxide-film thus; And

Under the state in substrate being impregnated into the above-mentioned oxidizing solution that is lower than azeotropic concentration, the above-mentioned oxidizing solution that is lower than azeotropic concentration is concentrated into more than or equal to azeotropic concentration, on the 1st oxide-film, forms the 2nd oxide-film thus.

12. method of manufacturing thin film transistor as claimed in claim 5 is characterized in that, the above-mentioned substrate that will form chemical oxide film possesses carborundum on the surface.

13. method of manufacturing thin film transistor as claimed in claim 6 is characterized in that, above-mentioned oxidizing solution is a nitric acid.

14. method of manufacturing thin film transistor as claimed in claim 1 or 2 is characterized in that, comprises the operation of above-mentioned chemical oxide film being carried out nitrogen treatment after above-mentioned oxide-film forms operation.

15. a thin-film transistor utilizes the described method of manufacturing thin film transistor of claim 1 and obtains, and it is characterized in that possessing: utilize oxidizing solution to carry out oxidation and the chemical oxide film that forms.

16. thin-film transistor as claimed in claim 15 is characterized in that, it is the high film of atomic density that above-mentioned chemical oxide film becomes near substrate one side.

17., it is characterized in that above-mentioned chemical oxide film is a grid oxidation film as claim 15 or 16 described thin-film transistors.

18. a display unit is characterized in that, possesses the described thin-film transistor of claim 15.

19. the method for modifying of an oxide-film is characterized in that, carries out the described oxide-film of claim 1 at the oxide-film of membrane thickness unevenness and forms operation, improves the membranous of above-mentioned oxide-film thus.

20. the method for modifying of an oxide-film is characterized in that, carries out the described oxide-film of claim 1 at membranous uneven oxide-film and forms operation, improves the membranous of above-mentioned oxide-film thus.

21. the formation method of an oxide-film is characterized in that, has following operation:

Make the oxidizing solution or its gas contact semiconductor that are lower than azeotropic concentration, on above-mentioned semiconductor surface, form the 1st chemical oxide film thus; And

Make more than or equal to the oxidizing solution of azeotropic concentration or the semiconductor of its gas contact formation the 1st chemical oxide film, form the 2nd chemical oxide film thus.

22. the formation method of an oxide-film is characterized in that, possesses following operation:

Make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, on above-mentioned semiconductor surface, form the 1st chemical oxide film thus; And

Make oxidizing solution or its gas generation effect of high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film thus.

23. the formation method as claim 21 or 22 described oxide-films is characterized in that, concentrates and carries out Yi Bian form oxidizing solution that the operation of the 2nd chemical oxide film uses on one side the 1st chemical oxide film being formed.

24. the formation method as claim 21 or 22 described oxide-films is characterized in that, the thickness of the 2nd chemical oxide film is formed than the 1st chemical oxidation thickness.

25. the formation method as claim 21 or 22 described oxide-films is characterized in that, the operation that forms above-mentioned the 1st chemical oxide film and the 2nd chemical oxide film is above-mentioned semiconductor is impregnated in the above-mentioned oxidizing solution and carries out.

26. the formation method as claim 21 or 22 described oxide-films is characterized in that, above-mentioned semiconductor is to be selected from least a among monocrystalline silicon, polysilicon, amorphous silicon, carborundum and the SiGe.

27. the formation method of oxide-film as claimed in claim 22 is characterized in that, the oxidizing solution of above-mentioned high concentration or its gas are more than or equal to the oxidizing solution of azeotropic concentration or its gas.

28. formation method as claim 21,22 or 27 described oxide-films, it is characterized in that above-mentioned oxidizing solution or its gas comprise: be selected from nitric acid, cross chloric acid, at least a solution, its gas or their mixture in the group of mixed solution, chloroazotic acid and the boiling water of mixed solution, sulfuric acid and the nitric acid of mixed solution, ammoniacal liquor and the hydrogen peroxide of mixed solution, sulfuric acid and the hydrogen peroxide of sulfuric acid, ozone dissolving water, hydrogen peroxide, hydrochloric acid and hydrogen peroxide.

29. the formation method of oxide-film as claimed in claim 22, it is characterized in that, at least a and the concentration that the oxidizing solution of above-mentioned low concentration or its gas are selected from aqueous solution of nitric acid, aqueous sulfuric acid and cross chloric acid aqueous solution's group is lower than solution or its gas of azeotropic concentration

The oxidizing solution of above-mentioned high concentration or its gas are selected from least a in the above-mentioned aqueous solution group and are solution or its gas more than or equal to azeotropic concentration.

30. formation method as claim 21,22,27 or 29 described oxide-films, it is characterized in that, comprise: the operation of after above-mentioned semi-conductive surface forms the 1st chemical oxide film and the 2nd chemical oxide film, above-mentioned the 1st chemical oxide film and the 2nd chemical oxide film being carried out nitrogen treatment.

31. the manufacture method of a semiconductor device is characterized in that, possesses: the oxide-film that utilizes the formation method of claim 21 or 22 described oxide-films to form the 1st chemical oxide film and the 2nd chemical oxide film forms operation.

32. the manufacture method of a semiconductor device is characterized in that, possesses following operation:

Make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, on above-mentioned semiconductor surface, form the 1st chemical oxide film; And

Make oxidizing solution or its gas generation effect of high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

33. the manufacture method of semiconductor device as claimed in claim 32, it is characterized in that, the oxidizing solution of above-mentioned low concentration or its gas are from being selected from nitric acid, crossing chloric acid, select in the group of the mixture of at least a and water the sulfuric acid and selecting in the concentration range lower than azeotropic concentration

The high concentration of the set point of the concentration range that surpasses above-mentioned low concentration is selected and be chosen to be to the oxidizing solution of above-mentioned high concentration or its gas from the group of said mixture.

34. manufacture method as claim 32 or 33 described semiconductor devices, it is characterized in that the oxidizing solution of above-mentioned high concentration or its gas comprise: be selected from as with the azeotropic nitric acid of the azeotropic mixture of water, as with the azeotropic sulfuric acid of the azeotropic mixture of water and as crossing at least a solution or its gas in the chloric acid with the azeotropic of the azeotropic mixture of water.

35. the manufacture method as claim 32 or 33 described semiconductor devices is characterized in that, above-mentioned semiconductor comprises: be selected from least a among monocrystalline silicon, polysilicon, amorphous silicon, carborundum and the SiGe.

36. manufacture method as claim 32 or 33 described semiconductor devices, it is characterized in that, comprise: the operation of after above-mentioned semi-conductive surface forms the 1st chemical oxide film and the 2nd chemical oxide film, above-mentioned the 1st chemical oxide film and the 2nd chemical oxide film being carried out nitrogen treatment.

37. the manufacture method of semiconductor device as claimed in claim 32, it is characterized in that, have following operation: after above-mentioned semi-conductive surface forms the 1st chemical oxide film and the 2nd chemical oxide film or after above-mentioned the 1st chemical oxide film and the 2nd chemical oxide film are carried out nitrogen treatment, at least a coverlay in oxide-film, silicon nitride film, high dielectric film and the ferroelectric thin film that formation is made by chemical vapor deposition (CVD).

38. semiconductor device, utilize the manufacture method of claim 31 or 32 described semiconductor devices and obtain, it is characterized in that possessing: utilize the chemical oxide film of the oxidizing solution of the oxidizing solution of above-mentioned low concentration and high concentration with semiconductor oxide.

39. the manufacturing installation of a semiconductor device is characterized in that, possesses following function:

Make the oxidizing solution of low concentration or its gas to semiconductor surface generation effect, form the 1st chemical oxide film at above-mentioned semiconductor surface; And

Make oxidizing solution or its gas generation effect of high concentration, on above-mentioned the 1st chemical oxide film, form the 2nd chemical oxide film.

40. the manufacturing installation of a semiconductor device has the oxide-film formation portion that forms chemical oxide film on semiconductor surface, it is characterized in that,

Above-mentioned oxide-film formation portion has following function: utilize the formation method of claim 21 or 22 described oxide-films or the manufacture method of claim 31 or 32 described semiconductor devices to come to form chemical oxide film at semiconductor surface.

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