CN100501949C - Production method for forming semiconductor device - Google Patents

Production method for forming semiconductor device Download PDF

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CN100501949C
CN100501949C CNB2006101014204A CN200610101420A CN100501949C CN 100501949 C CN100501949 C CN 100501949C CN B2006101014204 A CNB2006101014204 A CN B2006101014204A CN 200610101420 A CN200610101420 A CN 200610101420A CN 100501949 C CN100501949 C CN 100501949C
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silicon oxide
film
oxide film
temperature
semiconductive thin
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CN1967791A (en
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山崎舜平
张宏勇
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Semiconductor Energy Laboratory Co Ltd
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Semiconductor Energy Laboratory Co Ltd
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Abstract

A low temperature process for fabricating a high-performance and reliable semiconductor device in high yield, comprising forming a silicon oxide film as a gate insulator by chemical vapor deposition using TEOS as a starting material under an oxygen, ozone, or a nitrogen oxide atmosphere on a semiconductor coating having provided on an insulator substrate; and irradiating a pulsed laser beam or an intense light thereto to remove clusters of such as carbon and hydrocarbon to thereby eliminate trap centers from the silicon oxide film. Also claimed is a process comprising implanting nitrogen ions into a silicon oxide film and annealing the film thereafter using an infrared light, to thereby obtain a silicon oxynitride film as a gate insulator having a densified film structure, a high dielectric constant, and an improved-withstand voltage.

Description

The manufacture method of semiconductor device
The application is to be August 27, application number in 1993 the dividing an application for the application of " manufacture method of semiconductor device " that be 200410045674.X and denomination of invention the applying date.
Technical field
The present invention relates to adopt the semiconductor device and the manufacture method thereof of dielectric film, this device is called as thin-film transistor (hereinafter referred to as " TFT ").The invention still further relates to 700 ℃ or more under the low temperature on dielectric substrate high productivity make the method for high performance reliable insulated gate semiconductor device and the method for making integrated circuits (IC) by a plurality of such semiconductor device of assembling.
This device can be used as drive circuit, the TFT of SOI (silicon on the insulator) circuit and the TFT of the conventional semiconducter IC such as microprocessor, microcontroller, microcomputer and semiconductor memory of active matrix, image sensor of LCD etc. etc.
Background technology
Usually, liquid crystal display device and image sensor be as employing be integrated in the TFT on the glass substrate device and by known.Generally, adopt the insulated-gate type field effect semiconductor device of thin-film transistor to be used for above-mentioned conventional device, and get used to the gate insulating film of silicon oxide film as those TFT.
Yet, adopt silicon oxide film can produce some problems as the TFT of gate insulating film, for example, the leakage current that causes by the pin hole in the gate insulating film, increase the limitation of film thickness (electric capacity of gate insulating film depends on film thickness and dielectric constant), because density deficiency (that is, film is too soft) causes as the required various characteristics instability of dielectric film, and the problem brought of the fixed charge the sodium ion in sneaking into gate insulating film.
Recently, people further investigate for the method for making insulation canopy N-type semiconductor N device (MOSFET) on dielectric substrate.Those IC that form on dielectric substrate can adapt to high-speed driving well, because the IC that forms on insulator can not produce stray capacitance.Opposite with these IC, the speed of service of conventional IC is to be subjected to stray capacitance, i.e. the restriction of the electric capacity between line and the substrate.The MOSFET that forms on dielectric substrate and have a film active layer is called as thin-film transistor (TFT).For example in conventional semiconducter IC, can find TFT as the load transistor of SRAM.
In addition, some new products, for example, the drive circuit of the optics such as LCD and image sensor requires the semiconducter IC that forms on transparent substrates.TFT can be assembled among the IC, but IC must be formed on the wide zone, and therefore requires to make TFT by low temperature process.Moreover, for example, in device, preferably reduce packaging density by forming the ground floor semiconducter IC or whole semiconducter IC being formed on the same dielectric substrate with monolithic form with a plurality of end points that are connected with semiconducter IC on the dielectric substrate one by one.
Usually, the quality of TFT is by the preparation high-performance (promptly, sufficiently high mobility) semiconductive thin film improves, and the high-performance semiconductor film is to form by the high light irradiation such as laser beam or by the crystallinity that the thermal anneal process of 450 to 1200 ℃ of scopes is improved amorphous or half amorphous or microcrystalline film.The amorphous TFT of the semiconductive thin film of employing non-crystalline material can make beyond doubt, and still, its application greatly is subjected to the restriction of low operating rate, and low operating rate is owing to too low mobility, and this mobility is 5cm 2/ Vs or lower is about 1cm usually 2/ Vs perhaps is subjected to the restriction that it can not form P channel TFT (PTFT).Has 5cm 2/ Vs or more the TFT of high mobility can only be in 450-1200 ℃ of temperature range obtain after the annealing in process.PTFT can only make after film experiences this annealing in process.
Yet, in needing the technology of high temperature, have only strict selected backing material just can use.Particularly, be included in 900 to 1200 ℃ of so-called high-temperature technologies that carry out heat superiority is arranged, because it allows to adopt the high-quality thin film that obtains by thermal oxidation as gate insulating film, but available substrate is limited to those by such as quartz, the substrate of the expensive material preparation of sapphire and spinelle and so on, and they also are not suitable as the substrate of large-area applications.
Different with above-mentioned high temperature process, in low temperature process, backing material can be selected in relative broad range, and described low temperature process is meant that for the whole technology that comprises the crystallisation step that adopts laser radiation, accessible maximum temperature is 750 ℃ or lower.But, aspect useful step accommodation and high yield, low temperature forms dielectric film and still has problem.Dielectric film can pass through the sputtering method deposit at low temperatures, but this technology remains not good, because its step accommodation is little and productive rate is low.Under low temperature and high yield condition, by chemical vapor deposition (CVD) method silicon oxide deposition film also is known, such as, plasma CVD method, low pressure chemical vapor deposition method, with the atmospheric pressure cvd method, the aerification organic material (hereinafter referred to as organosilan) that wherein adopts the silicon atoms such as tetraethoxysilane (TEOS) is as raw material.But, formed film is rich in carbon atom and alkyl, and their cohesions form trap center.Therefore, those films are unsuitable for gate insulator, because they can not provide sufficiently high insulation property and have too high interface state density.
Above-mentioned employing organosilan can not be as the gate insulating film that requires quite high electrical property as raw-material silicon oxide film.Therefore, they can only experience under 700 ℃ or the higher temperature and just can use after the long oxidation processes.This heat treatment meeting damage substrate also influences output.
Summary of the invention
The present invention realizes by above-mentioned condition.
Therefore, an object of the present invention is under the condition of low temperature and good step accommodation to form a kind of oxide-film, but also improved output and improved the quality of film.
Another object of the present invention is the process that proposes a kind of TFT of manufacturing, the method can 700 ℃ or more under the low temperature combination by several technology of pointing out previously realize.
A further object of the present invention is to overcome the problems referred to above that existing gate insulating film exists.And provide a kind of TFT that can produce the characteristic good of high stable.
Have found that above-mentioned purpose can realize by the following example according to the present invention.
The first embodiment of the present invention comprises: form silicon oxide film, described CVD method such as hot CVD (chemical vapor deposition) plasma CVD, optical cvd and light plasma CVD by decomposing the acquisition product with any CVD method deposit by organosilan (perhaps comprising the substitute products that replace the organosilan of wherein hydrogen, carbon or alkyl with fluorine); Use the film of the photoirradiation institute deposit such as laser pulse again,, especially, improve its characteristic by removing the trap center that carbon atom in the film and alkyl eliminate in the film to improve its characteristic.According to said method, can obtain the silicon oxide film of the gate insulating film of the suitable TFT of being used as.Be used for laser of the present invention and be pulse laser and preferably such as being excited the laser of emission ultraviolet (UV) light the molecular laser of Huaihe River, for example KrF, ArF, XeCl and XeF laser.
The second embodiment of the present invention comprises: form silicon oxide film by decomposing the product that obtains with any CVD method deposit by organosilan; The silicon oxide film that forms is exposed in the oxidizing atmosphere that comprises oxygen, ozone, nitrogen oxide etc.; And in film being heated to 150 to 400 ℃ temperature range, being 300nm or shorter UV photoirradiation with wavelength, thereby removing the trap center in the film.According to said method, can obtain the silicon oxide film of the gate insulating film of the suitable TFT of being used as.
Combination by the above-mentioned first embodiment of the present invention and second embodiment can obtain further beneficial effect.For example, can be exposed in the oxidizing atmosphere, and when film being heated to 150 to 400 ℃ temperature range, be the UV photoirradiation film of 300nm by the laser emission with wavelength by the silicon oxide film that organosilan obtains.
Another embodiment of the present invention comprises the surface portion that the nitrogen ion is injected dielectric film, this dielectric film The silicon oxide film that forms on semiconductor surface constitutes, so that form silicon oxynitride in this surface portion of dielectric film.By film being carried out this surfaces nitrided processing.Can make the surface densification of dielectric film and its dielectric constant is increased.Especially, this embodiment of the present invention is characterised in that, the nitrogen ion is injected into surface portion as the silicon oxide film of the gate insulating film deposit of TFT (insulated-gate type field effect transistor), makes to rebulid silicon oxynitride film as gate insulator.Silicon oxynitride film can be by chemical formula SiO xN yExpression, wherein x is 0 to 2, is preferably 0.5 to 1.5, y is 0 to 4/3, is preferably 0.5 to 1.
The surfaces nitrided processing of silicon oxide film is useful, because it makes thin film densification, the thin-film dielectric constant is improved and the thicker film of permission deposit, and has improved the total characteristic as the film of insulator.
Description of drawings
Fig. 1 is the step preface figure according to the process of manufacturing TFT of the present invention;
Fig. 2 is the step preface figure according to the another kind of manufacture method of TFT of the present invention;
Fig. 3 is the schematic diagram that is used for laser of the present invention and UV light processor;
Fig. 4 is the step preface figure according to the TFT manufacture method of an example of the present invention;
Fig. 5 is the step preface figure according to the TFT manufacture method of another example of the present invention;
Fig. 6 is the step preface figure according to the method for the another kind of TFT of manufacturing of another example of the present invention; With
Fig. 7 is the step preface figure according to the another kind of manufacture method of TFT of the present invention.
Embodiment
The first embodiment of the present invention comprises: decompose the product that obtains by deposit by organosilan and form silicon oxide film, described deposit can be realized by any CVD method, such as hot CVD, plasma CVD, optical cvd and light-plasma CVD; Shine the film of institute's deposit again with pulse laser beam, to improve its characteristic.Especially make film forfeiture trap center improve characteristic by carbon atom and the alkyl of removing in the film.According to said method, can obtain the silicon oxide film of suitable a surname as the gate insulating film of TFT.The laser that uses among the present invention is a pulsed laser, and preferably launches the laser of ultraviolet light, such as excimer laser, and for example KrF, ArF, XeCl and XeF laser.
High light is ultraviolet or infrared light preferably.As described later, ultraviolet light is effective to carbon atom and the alkyl of removing in the film.Infrared light Fast Heating film is to reduce the crystal defect in film and the density of the trap center the dangling bonds.
By the radiation of laser beam or infrared light, can improve the crystallinity of semiconductive thin film, for example, become crystalline state from amorphous state.Certainly, the crystalline improvement of semiconductive thin film can separate with the improvement of silicon oxide film and carries out.
Comprise according to a second embodiment of the present invention: form silicon oxide film by adopting any CVD method deposit to decompose the product that obtains by organosilan; The silicon oxide film that forms is exposed in the oxidizing atmosphere that comprises oxygen, ozone, nitrogen oxide etc.; When heating film to 150 is to 400 ℃ temperature range, be 300nm or shorter ultraviolet light irradiation with wavelength, so that remove trap center wherein.According to said method, can obtain the silicon oxide film of the insulated gate film of the suitable TFT of being used as.
Aforementioned first and second embodiment combination of the present invention can be obtained further beneficial effect.For example, can expose in the oxidizing atmosphere, and when heating film to 150 was to 400 ℃ temperature range, using the wavelength by the laser emission was the ultraviolet light irradiation of 300nm by the silicon oxide film that organosilan obtains.
Usually, the organosilan such as tetraethoxysilane (TEOS) comprises that those with the part substituent organosilan of fluorine as alkyl, ethyoxyl, hydrogen atom etc., are liquid under normal pressure and room temperature.Therefore, if desired, they can be heated under reduced pressure, introduce reative cell with gaseous state.When silicon oxide film is formed by the plasma CVD method deposit, an amount of oxygen is mixed mutually with organosilan, to allow the adopting inert gas such as argon and helium to react as carrier gas.When being equipped with by low pressure chemical vapor deposition or atmospheric pressure cvd legal system, organosilan and ozone hybrid reaction if desired, can adopt above-mentioned carrier gas.
In said method, the crystalline annealing in process that is used to improve semiconductive thin film no longer is the highest step of temperature of the whole technology of decision, but the other factors such as hydrogenation annealing and gate oxidation films annealing becomes the decisive factor of the maximum temperature of technology.This allows in wide material ranges and selects backing material.More particularly, the maximum temperature of technology should be 700 ℃ or lower, is preferably 400 ℃ or lower.As mentioned above, the method according to this invention can or more be implemented under the low temperature at 700 ℃.Therefore, the problem that exists in the existing method promptly, owing to reasons such as thermal expansion, warpage cause pattern displacement on the large tracts of land substrate, can be prevented to produce in the method for the invention.For example, method of the present invention can be made a plurality of TFT of very high degree of precision on a large tracts of land substrate that is of a size of 300mm * 400mm.Therefore can see that productivity ratio can be improved by adopting method of the present invention.
In addition, be considered to usually be used to make TFT to work thereon because the soda-lime glass of the too low TFT of the being not suitable as substrate of softening point, can adopt through after the suitable processing in the method for the invention at it.
According to the present invention, a kind of method of making semiconductor device comprises the following steps:
On substrate, form semiconductive thin film;
Form the protectiveness dielectric film on described semiconductive thin film, described protectiveness dielectric film is a printing opacity.
With the described semiconductive thin film of photoirradiation, to improve its crystallinity;
Remove described protectiveness dielectric film, to expose a surface of described semiconductive thin film;
Employing comprises the raw material of organosilan, by chemical vapor deposition, forms silicon oxide film on the surface that exposes;
Use up the described silicon oxide film of irradiation at least; And
On described silicon oxide film, form grid.
The light of irradiation semiconductive thin film is laser pulse or infrared light.And the photoirradiation of described semiconductive thin film continued 5 seconds to 5 minute, so that make the temperature of described semiconductive thin film rise to 1000 to 1300 ℃, then reduce the temperature of described semiconductive thin film by 30 to 300 ℃/second speed by 30 to 300 ℃/second speed.At least only laser pulse, infrared light or the halogen light of irradiation silicon oxide film.And described light continues 5 seconds to 5 minute to the irradiation of described silicon oxide film at least, so that make the temperature of described silicon oxide film rise to 1000 to 1300 ℃, then reduce the temperature of described silicon oxide film by 30 to 300 ℃/second speed by 30 to 300 ℃/second speed.
First application examples of the present invention comprises the peripheral circuit of the active matrix (AM) of a liquid crystal display device (LCD) that is used for drive using amorphous silicon (a-Si) TFT.In general, can be by at 400 ℃ or more on alkali-free glass (as Corning7059) substrate, form a-SiTFT under the low temperature and make a-SiTFT-AMLCD.From its high viewpoint of closing resistance break, the a-SiTFT optimum is as switch element, and but, as previously mentioned, its operating rate is low, and can not make CMOS by it.Therefore, adopt monocrystalline integrated circuit (IC) to form peripheral circuit usually, and adopt TAB (band is bonding automatically) method or similar approach the end points of matrix to be connected to the end points of IC.Yet this assemble method is not suitable for the size that reduces pixel, and required thus cost accounts for the major part that is used to make the required complete cost of whole assembly.
In conventional method, it is impossible forming the peripheral circuit that has matrix on same substrate.But, above-mentioned trouble can be eliminated in the method for the invention, can form under the roughly the same temperature of the temperature required with forming a-SiTFT because have the TFT of high mobility.
According to second application examples of the present invention, TFT for example can be formed on that soda-lime glass is a kind of than on the more inexpensive material of alkali-free glass.When on the soda-lime glass substrate, forming TFT, preferably at first on the surface of glass substrate, form the insulating coating of the silicon nitride that comprises as key component, aluminium oxide etc., and form again after the insulation primary coat film such as silica or similar material, form TFT.Movably (such as the sodium) ion that according to said method, can prevent to exist in the glass enters TFT.In addition, without NTFT, can lower mortality be formed for the TFT of matrix by using PTFT.Chance forms the raceway groove that makes the NTFT conducting from the removable ion that substrate enters NTFT, but the removable ion that may enter PTFT but can not form any raceway groove.
The 3rd application examples of the present invention provides the peripheral circuit of a kind of static drive simple matrix LCD.Ferroelectric liquid crystals (FLC) material has memory effect.Therefore, it can provide the image of high-contrast, even it is used among the simple matrix LCD.But, normally IC sets up by connecting with the method identical with the method that is used for a-SiTFT-AMLCD such as TAB method for used here peripheral circuit.Similarly, TAB is used to connect the peripheral circuit of LCD, and LCD described here is with static mode work according to the phase transformation between cholesteric phase and the nematic phase.The static drive LCD that comprises the combination of nematic liquid crystal and ferroelectric polymers proposed in for example JP-A-61-1152 (the unexamined open Japanese patent application of the word that contracts " JP-A-" expression of quoting here), but peripheral circuit still connects with the TAB method.
Because above-mentioned LCD drives in simple matrix, they can provide big image plane easily, and adopt inexpensive substrate and have high-resolution.High-resolution picture can only obtain by the spacing between the compression termination.But, the surface-assembled difficulty that this can IC turns to cost and realizes.Method of the present invention is integrated on the inexpensive substrate with making the peripheral circuit monolithic, and needn't consider the problem of heat.
The 4th application examples of the present invention comprises a kind of so-called three-dimensional IC, and it is by forming TFT and make being provided with on the semiconducter IC of metal connector.
Obviously, can also from the present invention, obtain various application forms.
Describe the present invention in more detail below with reference to non-limitative example.But, should be appreciated that the present invention can not be considered to be confined to these examples.
Example 1
With reference to Fig. 1, will be described below according to the method for manufacturing TFT of the present invention (a kind of semiconductor device).At first, (be of a size of 300mm * 300mm, its size also can be 100mm * 100mm), and to go up deposition thickness be 100 to 300nm silicon oxide film 102, as the bottom oxide film at Corning7059 substrate 101.Can be by sputter or using plasma CVD method deposition oxide film in oxygen atmosphere, a kind of method in back comprises decomposes TEOS and deposit product, makes film annealing then in 450 to 650 ℃ temperature range.
After this, by plasma CVD method or LPCVD method deposited amorphous silicon thin film 103, the thickness of this film is 30 to 150nm, is preferably 50 to 100nm.Then, with the KrF excimer laser irradiation film of the pulsewidth that works in the wavelength of 248nm and 20ns, shown in Fig. 1 (A), to improve the crystallinity of silicon thin film 103.Laser irradiating device used herein is shown in Fig. 3 (B).Can improve the crystallinity of film by rapid thermal annealing (RTA) method, described method comprises that strong light carries out irradiation the laser beam with resembling.For by the irradiation laser bundle or heat crystallization silicon thin film further anneal still effectively with above-mentioned high light.Infrared light such as the halogen light of the peak wavelength with 1.3 μ m is effective especially for optionally heating silicon fiml, because silicon thin film more can absorbing light than glass substrate.
Laser irradiation is to be to carry out under 10mTorr or the lower condition sample being heated to 150 to 400 ℃ temperature range and controlling pressure.As a result, obtained having the film of well-crystallized.The energy density 200 of the laser beam that is shone is to 400mJ/cm 2, be preferably 250 to 300mJ/cm 2The crystallinity of thus obtained silicon thin film 103 is with the analysis of Raman (Raman) spectroscopic scatterometer, at 515cm -1The place observes the spectrum peak of a broad, and this peak is different from should be in 521cm -1The spectrum peak of the monocrystalline silicon at place.
Silicon layer 103 needle drawings are formed island-shaped area, to provide NTFT district 104 and PTFT district 105.By decomposing TEOS and adopting RF plasma CVD (chemical vapor deposition) method to form grid oxidation film 106 in the above by decomposition product and oxygen silicon oxide deposition film together, simultaneously underlayer temperature is controlled in 200 to 500 ℃ the scope, preferred 200 to 400 ℃, be preferably 200 to 250 ℃.TEOS (as a kind of organosilan) and oxygen are supplied with than 1:1 to 1:3 by pressure, simultaneously pressure are controlled in 0.05 to 0.5Torr the scope, RF power are controlled in 100 to 250W the scope.This step also can adopt TEOS and ozone gas to realize by low pressure chemical vapor deposition or atmospheric pressure cvd method as raw material, simultaneously underlayer temperature is controlled in 150 to 400 ℃ the scope, preferably in 200 to 250 ℃ the scope.
Formed silicon oxide film is carried out thermal anneal process in nitrogen containing atmosphere under 400 to 700 ℃ of temperature.
Can not be used as gate oxidation films through deposit and heat treated sull, because it contains a large amount of alkyl that plays the trap center effect.For this reason, after the silicon oxide film thermal anneal process, adopt the device shown in Fig. 3 at least silicon oxide film (grid oxidation film) to be carried out laser beam irradiation, to reduce the trap center quantity in this sull.With reference to Fig. 3 (B), this device comprises an operating room 308, and this operating room is provided with oxygen inlet 310, outlet 313 and quartz window 309, and the support 311 that heater 314 is housed is arranged in the operating room, few sample 312 of just laying thereon.Laser beam or high light pass window 309 irradiation samples.High light irradiation can reduce the trap center number in the sull, simultaneously, improve the density of silicon oxide film and improve semiconductor and silicon oxide film between the interface.
This step realizes in the following manner.At first, the operating room being evacuated to sufficiently high vacuum degree, (is NO with oxygen, ozone or nitrogen oxide 2, NO and N 2O) in the input service chamber, the irradiation of beginning laser beam or high light.Irradiation is under 10Torr or lower reduced pressure, or carry out in the oxidizing atmosphere of atmospheric pressure.Usually, adopt the KrF laser beam as above-mentioned laser beam.High light generally is incoherent UV (ultraviolet) light.When adopting laser, laser with 250 to 300mJ/cm 2Energy density carry out 10 times the emission.Temperature during the irradiation preferably maintains in 150 to 400 ℃ the scope, and representative value is 300 ℃.Adopt IR (infrared) light as high light, for example wavelength is the halogen light of 1.3 μ m, and it also is useful carrying out RTO (rapid thermal oxidation).RTO technology comprises with the instantaneous heated oxide thing of IR light film, to reduce the trap center number in the film.The surface of being shone is rapidly heated in 1000 to 1300 ℃ the temperature range, preferably in 1000 to 1200 ℃ scope, to improve the characteristic at the interface between semiconductor and the gate oxidation films.Can make the interface state density of gate oxidation films reduce to 10 by annealing 11Cm -2Or it is lower.In addition, under the situation of RTO, the light of irradiation gate oxidation films should continue 5 seconds to 5 minutes at least, so that the temperature of gate oxidation films rises to 1000 to 1300 ℃ with 30 to 300 ℃/second speed, then reduces the temperature of gate oxidation films again with 30 to 300 ℃/second speed.
Subsequently the silicon oxide film that forms is carried out thermal annealing, annealing is to carry out in the atmosphere that is comprising nitrogen or oxygen under 400 to 700 ℃ of temperature.
With the thick aluminium film of electron-beam vapor deposition method deposit 200nm to 5 μ m, and this aluminium film carried out needle drawing, thereby on grid oxidation film, obtain gate electrode 107 and 108, shown in Fig. 1 (C).Adopting this aluminium film of electron beam deposition method deposit is for obtaining having the film of high reflectance, because this film is wanted the laser irradiation of sun retaining later on.So the aluminium film that obtains is smooth so that by observation by light microscope less than particle.By electron microscope observation to particle size be 200nm or littler.The size of these particles must control to less than Wavelength of Laser used in this method.
Adopt grid to make mask,,, impurity is injected in the island shape silicon fiml of each TFT by ion exposure island shape silicon fiml or by ion doping technology with self-aligned manner.More specifically, at first adopt hydrogen phosphide (PH 3) gas as impurity gas by 2 * 10 15To 8 * 10 15Cm -2Dosage inject phosphorus, after only island-shaped area 104 being covered with photoresist, adopt diborane as impurity gas by 4 * 10 15To 10 * 10 15Cm -2Dosage boron is only mixed people's island-shaped area 105.In this method, boron mixes in the film with the dosage that is higher than phosphorus.
Then, shown in Fig. 1 (D), make mask, use light such as wavelength is the KrF laser beam of 248nm by the formed structure of pulsewidth irradiation of 20nm, to recover the crystallinity of impaired doped region with gate electrode.The used device of laser irradiation step for this reason is shown in Fig. 3 (B).Laser motion in 200 to 400mJ/cm 2The energy density of scope, preferably 250 to 300mJ/cm 2Scope.
In this case, sample does not heat.So just, obtained N type impurity (phosphorus) district 109 and 110, and p type impurity (boron) district 111 and 112.These regional sheet resistances are in the scope of 200 to 800 Ω/.Adopt TEOS as raw material, and under the situation of using plasma CVD method with the oxygen combination, or under the situation of using low pressure chemical vapor deposition or atmospheric pressure cvd method with combined with ozone, the thick silicon oxide film of deposit 300nm in the above is as interlevel insulator 113.In the overall process of this step, substrate temperature maintains in 150 to 400 ℃ of energy ranges, is preferably 200 to 300 ℃.
After in source/drain region of TFT, leaving contact hole, form aluminium line 114-116.Fig. 1 (E) shows a phase inverter, and it comprises a NTFT in left side and a PTFT of opposite side.The mobility of TFT is 50-100cm for NTET 2/ Vs, and be 30 to 100cm for PTFT 2/ Vs.Because the high technology temperature in this example is 400 ℃ or lower, therefore on the alkali-free glass substrate such as Corning7059, produces and shrink or warpage.The result is can make large area display or drive circuit well by above-mentioned substrate, because do not produce displacement basically as the figure on above-mentioned large-sized substrate.
Example 2
With reference to Fig. 2, do following description with the technology that forms the AMLCD element on the soda-lime glass substrate, prepare TFT according to the present invention.At first, by thickness be on 1.1mm and all surfaces that is of a size of the substrate 201 that the soda-lime glass plate of 300mm * 400mm makes deposition silicon nitride film 202 as the barrier layer.Because soda-lime glass is rich in sodium, so the deposit of using plasma CVD method is as the silicon nitride film on barrier layer, and film thickness is 5 to 50nm, is preferably 5 to 20nm, to prevent that the sodium diffusion takes place in TFT.This by the technology of making the barrier layer with silicon nitride or aluminum oxide film coated substrate be disclosed in Japanese patent application NO. by the applicant application flat-3-238710 peace-3-238714 in.
After oxide (silica) bottom 203 forms, be 30 to 150nm to be preferably 30 to 50nm silicon fiml 204 by LPCVD or plasma CVD method deposition thickness.The dehydrogenation of under 400 ℃ of temperature this film being carried out 1 hour is handled, and needle drawing forms the active layer of island shape semiconductor district as TFT then.Adopt TEOS as raw material by plasma CVD method deposit gate insulating film 205 in oxygen atmosphere, this film thickness is 70 to 120nm, typical thickness is preferably in 200 to 350 ℃ of scopes for the 100nm underlayer temperature maintains 400 ℃ or lower, shrinks on substrate or warpage preventing.But, formed silicon oxide film contains a large amount of alkyl and many trap centers.Particularly, for example, interface state density reaches 10 12Cm -2Or higher, it head and shoulders above the density that gate insulating film allowed.
Therefore, shown in Fig. 2 (A), use by KrF laser emitted laser bundle or photoirradiation gate insulating film 208 and island shape semiconductor district 204 with suitable intensity, improving the crystallinity in island shape semiconductor district, and by reducing the characteristic that wherein trap center number improves gate insulating film 205.In other words, this step has comprised the improvement of the crystallization and the grid oxidation film of silicon fiml, and this finishes respectively in two steps in aforesaid example 1.If used high light, so with IR light for example the halogen light of wavelength 1.3 μ m anneal, especially effective in the case.
Laser irradiation in this step is preferably carried out existing under the condition of excess of oxygen under 10Torr or lower decompression.Decompression is preferable selection, because the carbon atom that exists in sull can be emitted at an easy rate.The oxidation pressure-controlled is in 1 to 10Torr scope for example.Laser beam presses 250 to 300mJ/cm 2Energy density irradiation, and launch 10 times.Temperature preferably maintains in 150 to 400 ℃ the scope, and representative value is 300 ℃.Laser irradiation adopts the device shown in Fig. 3 (B) to carry out.As a result, silicon fiml 204 has improved crystallinity, and the interface state density of gate oxidation films is reduced to 10 11Cm -2Or it is lower.
With with example 1 in after identical method forms aluminium gate, total is immersed in the electrolyte as anode with substrate, and applies electric current, so that to form thickness on the surface of interior aluminium line be the anodized coating 209 of 206nm comprising gate electrode.Anodizing technology be disclosed in Japanese patent application NO. by the applicant application flat-4-30220, flat-4-38637 peace-4-54322 in.The structure that obtains after this step is shown in Fig. 2 (B).In addition, when finishing anodic oxidation, negative voltage oppositely can be added structure so far; For example, can apply the voltage of-100 to-200 volts of scopes in 0.1 to 5 hour time, preferably underlayer temperature be maintained simultaneously in 100 to 250 ℃ the scope, representative value is 150 ℃.By adopting this additional step, the moving iron of intersection in the silica or silica and silicon can be attracted to aluminum gate electrode.In anode oxidation process or thereafter the technology that gate electrode is applied negative voltage be disclosed in the Japanese patent application NO. that applied on April 7th, 1992 by the applicant flat-4-1155-3 in.
To inject silicon layer by ion doping as the boron of p type impurity with self-aligned manner subsequently, forming source/drain region 208 and 209 of TFT, and energy density is 250 to 300mJ/cm 2The KrF laser beam irradiation, to recover crystallinity by the silicon fiml of ion doping process-induced damage.After laser irradiation, the sheet resistance in source/drain region is in the scope of 300 to 800 Ω/.In this step, by high light preferably IR photoirradiation annealing be useful.
After forming interlayer dielectric 210, adopt ITO to form pixel contact layer 211 with polyimides.After this form contact hole, so that with chromium/aluminium multilayered films in the source of TFT/drain region sets up contact 212 and 213, chromium/aluminium multilayered films comprises that thickness is that 20 to 200nm representative values are that lower floor's chromium film and the thickness of 100nm is that 100 to 2000nm representative values are the upper strata aluminium film of 500nm.Multilayer film preferably adopts the sputtering method consecutive deposition.One of two contacts that obtain thus 213 are connected to ITO.At last, in hydrogen under 200 to 300 ℃ temperature with this structure annealing in process 2 hours, to finish the hydrogenation of silicon.So just obtained a TFT who finishes.A plurality of this TFT of preparation simultaneously are assembled into a matrix, to obtain an AMLCD device.
Example 3
With reference to Fig. 1, the technology of another kind of TFT produced according to the present invention is done following description.At first, on Corning7059 substrate 101 the thick silicon oxide film of deposit 100 to 300nm as underlying oxide film.After this by plasma CVD or by LPCVD deposited amorphous silicon thin film 103, these film 103 thickness are 30 to 150nm, are preferably 50 to 100nm.Subsequently, shown in Fig. 1 (A), with this film of KrF excimer laser irradiation that runs on 248nm wavelength and 20ns pulsewidth, to improve the crystallinity of silicon fiml 103.Can silicon fiml be heated to the crystallinity of improving this film in 1000 to 1200 ℃ the temperature range by irradiation strong light as laser beam.
Silicon layer 103 needle drawings are become island-shaped area, to provide NTFT district 104 and PTFT district 105.By decompose TEOS (organosilan) and adopt the RF plasma CVD method by decomposition product with oxygen silicon oxide deposition film, form gate oxidation films 106 in the above.The oxide-film of deposit can not be used as gate oxidation films like this, because it contains a large amount of alkyl that plays the trap center effect.Owing to this reason, adopt the device shown in Fig. 3 (A) irradiation laser bundle and high light simultaneously, to reduce the number of the trap center in the oxide-film.This step also can make the extremely close of oxide-film.High light can UV (ultraviolet) light or is carried out the IR light of Fast Heating simultaneously.With reference to Fig. 3 (A), this device comprises an operating room 301, and this operating room is provided with the oxygen inlet 305 that Oxygen Flow is provided, 306 and UV lamps 303 of an outlet; The support 302 that heater 307 is housed is arranged in the operating room so that sample 304 is put thereon.With wavelength is 300nm or shorter UV (ultraviolet) light irradiation gate oxidation films at least, to realize annealing.In this device, adopt a 40WUV lamp energy emission peak wavelength to be approximately the light of the spectrum of 250nm.
In the operating room, oxygen, ozone or nitrogen oxide (NO for example 2, NO and N 2O) air-flow is blown into over against sample.Needn't establish the particular step that the operating room is evacuated to vacuum.Therefore, can under atmospheric pressure, realize the UV rayed.UV light makes oxidizing gas experience photochemical reaction, thereby produces active oxygen or ozone.These active materials subsequently with silicon oxide film in reaction such as carbon, hydrocarbon, thereby the carbon atom concn in the film is reduced to enough low level.In course of reaction, sample temperature preferably remains in 150 to 400 ℃ the scope, and representative value is 300 ℃.As a result, interface state density is reduced to 10 11Cm -2Or it is lower.
Device shown in Fig. 3 (C) can be used for the device shown in the alternate figures 3 (A).With reference to Fig. 3 (C), this device comprises an operating room 315, and this operating room has an oxidation import 320,321 and UV lamps 317 of an outlet; Support 318 is arranged in the operating room and is used for laying sample 319 thereon.In this device, the oxidizing gas such as oxygen, ozone and nitrogen oxide is introduced into the operating room after the operating room is evacuated to sufficiently high vacuum degree.
Adopt the thick aluminium film of electron-beam vapor deposition method deposit 200nm to 5 μ m, and with its needle drawing, on gate oxidation films, to obtain gate electrode 107 and 108, shown in Fig. 1 (C).As mask, by carrying out ion doping technology, impurity is injected island shape silicon fiml with each TFT with grid by self-aligned manner.Shown in Fig. 1 (D), use the pulsewidth irradiation formed structure of the KrF laser of wavelength 248nm with 20nm; Crystallinity with the doped region that recovers damage.So just, obtained N type impurity (phosphorus) district 109 and 110, and p type impurity (boron) district 111 and 112.The sheet resistance in these districts is in the scope of 200 to 800 Ω/.Adopt TEOS as the raw material silicon oxide film of deposit 300nm in the above.
After source/drain region of TFT forms contact hole, form aluminium line 114 and 116.Fig. 1 (E) shows a phase inverter, and it is included in a NTFT in left side and a PTFT of opposite side.The mobility of TFT is 50 to 100cm for NTFT 2/ Vs is 30 to 100cm for PTFT 2/ Vs.So just, obtain one five bit shift register, and confirmed, under 20 volts drain voltage, can be operated in 10MHz or higher frequency.
Example 4
With reference to Fig. 7, the method for TFT constructed in accordance is done following description.At first, (be of a size of 300nm * 300mm, its size also can be that 100mm * 100mm) goes up the thick silicon oxide film 102 of deposit 100 to 300nm as underlying oxide film at Corning7059 substrate 101.This oxide-film by in oxygen atmosphere with sputtering method or the deposit of using plasma CVD method, the latter comprises and decomposes TEOS and deposit product, then in 450 to 650 ℃ temperature range this film is carried out annealing in process.
After this by plasma CVD method or by LPCVD method deposited amorphous silicon thin film 103, this film thickness is 30 to 150nm, is preferably 50 to 100nm.Subsequently shown in Fig. 7 (A), with this film of KrF excimer laser irradiation that runs on 248nm wavelength and 20ns pulsewidth, to improve the crystallinity of silicon fiml 103.Here adopt the laser irradiation device shown in Fig. 3 (B).Also can improve the crystallinity of this film by comprising flash annealing (RTA) method that irradiation resembles light strong the laser beam.To by swash penetrate laser beam or by heating crystallization silicon fiml further to adopt above-mentioned high light to carry out annealing in process also be effective.IR light such as peak wavelength is 1.3 μ m halogens is effective especially to optionally heating silicon fiml, because compare with glass substrate, silicon fiml more can absorbing light.
Laser irradiation is to be controlled under 10mTorr or the lower condition to carry out in sample being heated to 150 to 400 ℃ temperature range and with air pressure.As a result, obtained having the film of well-crystallized.Laser with 200 to 400mJ/cm 2Be preferably 250 to 300mJ/cm 2Energy density irradiation.With the crystallinity of the Raman diffused light spectrometer analysis silicon fiml 103 that obtains like this, at 515cm -1The place observes the spectrum peak of a broad, and this composes peak and should be in 521cm -1The spectrum peak difference of the monocrystalline silicon at place.
Silicon layer 103 needle drawings are become island-shaped area, thereby provide NTFT district 104 and PTFT district 105.In oxidizing gas, in 500 to 700 ℃ temperature range, make the surface portion oxidation in shape NTFT district, island 104 and PTFT district 105, and form 20 to 200 The first thick silicon oxide layer 120.Oxidizing gas can be for example 99.9% or more highly purified dried oxygen.By decompose TEOS (organosilan) and adopt RF plasma CVD (chemical vapor deposition) method by catabolite with oxygen on first silicon oxide layer deposit as the gate oxidation films 106 of second silicon oxide layer, simultaneously underlayer temperature is controlled at 200 to 500 ℃, preferred 200 to 400 ℃, be preferably 200 to 250 ℃.TEOS and oxygen provide by the pressure ratio of 1:1 to 1:3, simultaneously pressure are controlled at 0.05 to 0.5Torr, RF is led be controlled at 100 to 250W.This step also can adopt TEOS and ozone to realize by low pressure chemical vapor deposition or atmospheric pressure cvd method as raw material, simultaneously underlayer temperature is controlled at 150 to 400 ℃, is preferably in 200 to 25C ℃.
In blanket of nitrogen, the silicon oxide film that forms is carried out thermal anneal process at 400 to 700 ℃.
Oxide-film after deposit and the annealing can not be used as gate oxidation films like this, because it contains a large amount of alkyl that plays the trap center effect.For this reason, adopt the device shown in Fig. 3 (B), at least first and second silicon oxide layers are carried out irradiation, to reduce the quantity of the trap center in the oxide-film with laser beam.Light can be at least to 5 seconds to 5 of the first and second silicon oxide layer irradiation minute, so that make the temperature of described first and second silicon oxide layers rise to 1000 to 1300 ℃ with 30 to 300 ℃/second speed, reduce the temperature of first and second silicon oxide layers subsequently with 30 to 300 ℃/second speed.With reference to Fig. 3 (B), this device comprises an operating room 308, and this operating room has an oxygen inlet 310,313 and quartz windows 309 of an outlet.The support 311 that heater 314 is housed is arranged in the operating room, so that put sample 312 on it.Laser beam or high light expose on the sample by window 309.The irradiation of high light reduces the quantity of the trap center in the oxide-film, and silicon oxide film density is improved, and has improved the interface between semiconductor and the silicon oxide film.
This step is carried out as follows.At first, the operating room is evacuated to sufficiently high vacuum degree, and with oxygen, ozone or nitrogen oxide (as NO 2, NO and N 2O) guide in the operating room, so that the irradiation of beginning laser beam or high light.Irradiation is under 10Torr or lower decompression, perhaps carries out in the oxidizing atmosphere of atmospheric pressure.Usually, use the KrF laser beam as above-mentioned laser beam.High light generally is incoherent UV light.When adopting laser, laser should be with 250 to 300mJ/cm 2 Energy density emission 10 times.Temperature preferably maintains in 150 to 400 ℃ the scope during irradiation, and representative value is 300 ℃.Adopt IR light as high light, for example, wavelength is the halogen light of 13 μ m, and it also is useful carrying out RTO (rapid thermal oxidation) processing.RTO technology comprises that employing IR light carries out instantaneous heating to oxide-film, to reduce the quantity of the trap center in the film.Radiation exposed surface is rapidly heated to 1000 to 1200 ℃ temperature range, to improve the characteristic at the interface between semiconductor and the gate oxidation films.Can make the interface state density of gate oxidation films reduce to 10 by annealing 11Cm -2Or it is lower.
Under 400 to 700 ℃ of temperature, in nitrogen or oxygen atmosphere, the silicon oxide film that forms is carried out thermal anneal process subsequently.
With the electron-beam vapor deposition method deposition thickness is the aluminium film of 200nm to 5 μ m, handles through needle drawing again, obtains the gate electrode 107 and 108 shown in Fig. 7 (C).Coming deposit aluminium film by the electron beam deposition method is for obtaining to have the film of high reflectance, because will stop laser irradiation after this film.The aluminium film that obtains like this is smooth so that by observation by light microscope less than particle.By electron microscope observation, particle size is 200nm or littler.Must be with the size Control of these particles to less than used Wavelength of Laser in this method.
Adopt gate electrode as mask, by ion doping technology, impurity is injected in the island shape silicon fiml of each TFT with self-aligned manner.More particularly, at first adopt hydrogen phosphide (PH 3) gas as impurity gas by 2 * 10 15To 8 * 10 15Cm -2Dosage inject phosphorus, and after only covering island-shaped area 104, adopt diborane (B with photoresist 2H 6) press 4 * 10 as impurity gas 5To 10 * 10 15Cm -2Dosage boron is only injected island-shaped area 105.In this method, boron mixes in the film with the dosage that is higher than phosphorus.
Shown in Fig. 7 (D), be that the KrF laser beam of 248nm shines resulting structure by the pulsewidth of 20nm with wavelength, with the crystallinity of the doped region that recovers to be damaged.The device that is used for this laser irradiation step is shown in Fig. 3 (B).Laser runs on 200 to 400mJ/cm 2Scope in, be preferably in 250 to 300mJ/cm 2In the scope, sample does not heat in this case.So just obtained N type impurity (phosphorus) district 109 and 110, and p type impurity (boron) district 111 and 112.The sheet resistance in these districts is in the scope of 200 to 800 Ω/.Employing as raw-material TEOS with under the situation of plasma CVD method with the oxygen combination, perhaps under with the situation of low pressure chemical vapor deposition or atmospheric pressure cvd method with the thick silicon oxide film of combined with ozone deposit 300mm as interlayer dielectric 113.In the overall process of this step, substrate temperature maintains 150 to 400 ℃, preferably 200 to 300 ℃.
After TFT source/drain region forms contact hole, form aluminium line 114 to 116.Fig. 7 (E) illustrates a phase inverter, and it comprises the NTFT in left side and the PTFT of opposite side.The mobility of TFT is 50 to 100cm for NTFT 2/ Vs, and be 30 to 100cm for PTFT 2/ Vs.Because the high technology temperature in this example is 400 ℃ or lower, therefore produces on the alkali-free glass substrate such as the Corning7059 substrate and shrinks or warpage.The result is can make large area display or drive circuit well by above-mentioned substrate, because do not produce displacement basically as the figure on above-mentioned large-sized substrate.
Example 5
Below an example for preparing NTFT (isolated-gate field effect transistor (IGFET)) on the pixel capacitors part of AMLCD device is described.Certainly, for various improvement, basic structure is identical, the PTFT that described improvement forms such as replacing NTFT, and be the TFT of the peripheral circuit formation of liquid crystal display device.In addition, with this example in the structure of structural similarity can be used as the basic structure of the TFT of image sensor or other type i C.
With reference to Figure 4 and 5, this routine manufacturing process is described.With reference to Fig. 4, by sputtering method deposit 2000 on glass substrate 11 The silicon oxide film (not shown) of thickness is as base coating.Press known technology, by plasma CVD method deposit in the above 1000 Thick amorphous silicon film 12.Adopt 500 then Thick silica forms a mask 401, and this mask is provided with the position 14 that can expose following amorphous silicon membrane.
Then, by sputtering method deposit 20 Thick nickel silicide film.This film combines the crystallization of the amorphous silicon membrane 12 below quickening with component nickel.The thickness of this film is generally 5 to 200 In this case, nickel is used to accelerate the crystallization of amorphous silicon membrane, but the arbitrary element that belongs to the VIII family of periodic table all can be used to replacement nickel, such as, iron (Fe), cobalt (Co), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt).Those elements that belong to the md family of periodic table also are available, and what should propose especially is scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu) and zinc (Zn).Gold (Au) and silver (Ag) also are elements useful among the present invention.Wherein preferred especially Ni, Pd, Cu and Au.These elements can mix in the film by any means, such as, by adopting sputtering method, comprising plasma processing method, CVD method and vapor deposition method with plasma sputtering, deposition film on the upper surface of amorphous silicon membrane or lower surface, and inject directly by ion these elements are introduced amorphous silicon membrane.
After this remove silicon oxide film 401, so that nickel silicide film is optionally stayed on the surperficial position 14 of amorphous silicon membrane 12 as mask.Subsequently, by the irradiation facial position of selected table of the IR light transient heating amorphous silicon membrane of 1.3 mum wavelengths for example, make the nickel alloyization in the surperficial position 14 of amorphous silicon membrane.Can form the nickle silicide position in this way.This step is useful to crystallization effectively, because it makes nickel diffusion easily in the annealing crystallization step of back.
After this under 550 ℃ of temperature, in inert gas atmosphere, carry out 4 hours annealing in process.Heat treatment makes amorphous silicon membrane 12 crystallizations.In this step, crystallization takes place along the direction that is parallel to substrate, shown in the arrow among the figure 10, thus the needle-like of obtaining or column crystal.Crystal growth surpasses 40 μ m or longer distance.Crystallization processes needn't always carry out in a manner described, and also available laser beam irradiation perhaps carried out 24 hours under 600 ℃ of temperature according to known technology or thermal anneal process for more time.In addition, film also can keep amorphous state (with reference to figure 4 (B)).
Subsequently, set up active layer by the parts isolation.Here active layer is meant the zone that wherein will form source/drain region and channel formation region.Preferably remove with nickle silicide and form the nickeliferous district 14 that has introduced nickel, because these parts contain the nickel of excessive concentrations by etching.The left mid portion that is parallel to the substrate growth can be used as active layer well.
Be right after above-mentioned steps, form 1500 Thick silicon oxide film 13 is as gate insulating film.Preferably with the chlorine atom adding to this layer silicon oxide film, because after this this film can produce the gettering effect to foreign ion.
With reference to Fig. 4 (C), the nitrogen ion is injected in the silicon oxide film 13.In this step, on the surface of silicon oxide film, formed silicon oxynitride (silicon oxynitride) surface.But, should avoid the nitrogen ion to enter effective layer by silicon oxide film 13.The key of this step is only at the nearly nitrogenation that produces of the sun of silicon oxide film 13.
Oxynitride film 13 has 4 to 6 dielectric constant, and this is because the nitrogen ion injection in the above-mentioned steps causes.4 to 6 dielectric constant is higher than 3.8 to 4.0 dielectric constant of silicon oxide film.In addition, but film densification itself.As a result, solved such as the foreign ion in gate insulating film (sodium ion) transports, pin hole causes leakage and problem such as withstand voltage.In addition, can set up thicker gate insulating film, because its dielectric constant is higher than the dielectric constant of silicon oxide film.This advantage is favourable to solving leakage current and pin hole problem.
After the nitrogen ion is injected into gate silicon oxide dielectric film 13, preferably handle by carrying out photo-annealing again to gate silicon oxide dielectric film 13 irradiation infrared rays.The near infrared light that the use wavelength is roughly 1 to 2 μ m is especially useful, because can eliminate defective and dangling bonds in the silicon fiml 12 like this, and without the heating glass substrate, can also reduce the interface state density between gate insulating film 13 and the silicon fiml 12 simultaneously.These advantages have greatly promoted the improvement of TFT characteristic.
By to established 6000 on the gate insulating film 13 Thick aluminium film carries out needle drawing to be handled.Form grid contact 15.By anode oxidation method, make the surface oxidation of grid contact 25, thereby on the surface of grid contact 15, form oxide layer 151.This oxide layer
Figure C200610101420D0029110840QIETU
Be used to form the skew grid structure in the ion implantation step of back, its thickness is then determined the skew grid length.Therefore, forming thickness in this example is 2000 Oxide layer.The result has obtained the structure shown in Fig. 4 (D).
In this example, the contact of the canopy utmost point can adopt well known materials to be formed on the silicon.
With reference to Fig. 5 (A), infiltrating phosphorus (P) afterwards by ion implantation, form source/drain region 16 and 18 with self-aligned manner, and channel formation region 17.Then, make source/drain region annealing with laser beam or IR photoirradiation.
Form one deck polyimide film interlayer dielectric 19 in the above, and form ITO electrode 20 as pixel capacitors.After opening step, formation source/drain electrode 21 and 22.One in the contact 22 is connected to pixel capacitors 20.So just, obtained the complete NTFT of a band pixel capacitors, shown in Fig. 5 (B).
So the TFT that obtains comprises crystal silicon thin film, and this film is by forming along the silicon crystal of the direction growth that is parallel to substrate.Therefore, owing to the crystal boundary of charge carrier along single oriented single crystal moves, this TFT has high mobility.
Example 6
What this was for example described is a circuit structure of being made up of by complimentary fashion PTFT and NTFT.This routine structure can be used for the IC of image sensor, and the pixel of liquid crystal display device and peripheral circuit.
With reference to Fig. 6, this routine manufacturing process is described.On glass substrate 11, form 2000 by sputtering method Thick silicon oxide film (not shown) is as priming coat.Thereafter, by plasma CVD method deposited amorphous silicon thin film 12 in the above, and be heated to 600 ℃ of annealing in process 24 hours.
After above-mentioned heating crystallisation step, it is extremely useful adopting IR light that formed structure is carried out annealing in process.The irradiation of IR light has not only been eliminated defective and the dangling bonds in the silicon fiml, and therefore the crystallinity of also having improved silicon has also improved the density of film.The near infrared light that the use wavelength is about 1 to 2 μ m is especially useful, because the light of this scope can optionally be absorbed by silicon fiml, but is not that glass substrate absorbs.Therefore, silicon fiml can be heated to about 800 ℃ and not obvious heated substrate.
Then, set up two island shape active layers by the parts isolation.These two active layers will become PTFT and NTFT later.After this be 1500 by the sputtering method deposition thickness Silicon oxide film 13 as gate insulating film.According to example 5 in identical mode, carry out ion and inject, the nitrogen ion is mixed silicon oxide film, so that obtain silicon oxynitride film 13 as gate insulating film.Resulting structure is shown in Fig. 6 (B).
By to being formed at 6000 on the gate insulating film 13 Thick aluminium film carries out needle drawing to be handled, and forms grid contact 31 and 33.Make the surface oxidation of grid contact 31 and 33 by anodic oxidation, thereby on the surface of grid contact, form oxide layer 32 and 34.In addition, after sheltering, respectively phosphonium ion and boron ion are injected corresponding floor district in order with resist.According to said method, can obtain P type position 35 and 37 and N type position 38 and 40.So just obtained being used for source/ drain region 35 and 37 and be used for the channel formation region 36 of PTFT of PTFT together with self-aligned manner, and the source/drain region 38 and 40 and be used for the channel formation region 39 of NTFT that is used for NTFT.After this make source/drain region annealing with laser beam or IR photoirradiation.The result has obtained the structure shown in Fig. 6 (C).
After opening step, form polyimides or silicon oxide film as interlayer dielectric 41, form electrode 42,43 and 44 again.So just realized a complete structure that comprises PTFT and NTFT, the output of PTT and NTFT is connected to electrode 43.Resulting structure is shown in Fig. 6 (D).
As noted earlier, the present invention provides a kind of TFT by low temperature process and in the high yield mode.Particularly, when TFT is formed on the large tracts of land substrate when being used for active matrix and drive circuit, the present invention has made very big contribution to industry.Although do not specify in example, the present invention can be used for making so-called three-dimensional IC by stacked semiconductor IC on monocrystalline IC and other class IC.In addition, though above-mentioned example relates generally to various LCD, clearly, the present invention is used in the circuit that directly forms on the dielectric substrate, such as image sensor.Moreover, bring following benefit with silicon oxynitride film as gate insulating film.
Can obtain fine and close gate insulating film, this is solved problems such as the fixed charge in the gate insulating film, static puncture and pin hole; And, can form thick gate insulating film.
Though the present invention is described in detail with reference to specific embodiment, clearly, under the condition that does not break away from the spirit and scope of the present invention, those skilled in the art can make various conversion and improvement.

Claims (16)

1. a method that forms semiconductor device comprises the following steps:
On substrate, form semiconductive thin film;
Make described semiconductive thin film crystallization by heating;
After described crystallization steps, utilize the raw material that contain organic silane, on the semiconductive thin film of described crystallization, form silicon oxide film by plasma activated chemical vapour deposition;
After forming described silicon oxide film, infrared light is shone on the described at least silicon oxide film, to eliminate the carbon in the described silicon oxide film; And
On described silicon oxide film, form gate electrode,
Wherein, under 10 holders or lower decompression, or under the oxidizing atmosphere of atmospheric pressure, the described at least silicon oxide film of described rayed 5 seconds to 5 minutes, so that the speed with 30 to 300 ℃ of per seconds makes the temperature of described silicon oxide film be lifted to 1000 to 1300 ℃, the temperature of described silicon oxide film descends with the speed of 30 to 300 ℃ of per seconds subsequently.
2. the method for claim 1, wherein described light also shines on the described semiconductive thin film.
3. the method for claim 1 also comprises the steps:
With described gate electrode is mask, makes ion exposure to described semiconductive thin film by self-aligned manner; And
After described ion exposure step, be that mask makes illumination be mapped to described semiconductive thin film with described gate electrode.
4. the method for claim 1, wherein described only halogen light.
5. the method for claim 1, wherein carry out the formation of described silicon oxide film with 200 to 500 ℃ underlayer temperature.
6. the method for claim 1 also is included in before the described irradiating step, described silicon oxide film is carried out the step of thermal annealing in containing the atmosphere of nitrogen with 400 to 700 ℃ temperature.
7. the method for claim 1 also is included in after the described irradiating step, described silicon oxide film is carried out the step of thermal annealing in the atmosphere that comprises the gas of selecting from the group that comprises nitrogen and oxygen with 400 to 700 ℃ temperature.
8. a method that forms semiconductor device comprises the following steps:
Utilization contains the raw material of organic silane, forms silicon oxide film by plasma activated chemical vapour deposition; And
After forming described silicon oxide film, infrared light is shone on the described silicon oxide film, eliminating the carbon in the described silicon oxide film,
Wherein, under 10 holders or lower decompression, or under the oxidizing atmosphere of atmospheric pressure, the described at least silicon oxide film of described rayed 5 seconds to 5 minutes, so that the speed with 30 to 300 ℃ of per seconds makes the temperature of described silicon oxide film be lifted to 1000 to 1300 ℃, the temperature of described silicon oxide film descends with the speed of 30 to 300 ℃ of per seconds subsequently.
9. a method that forms semiconductor device comprises the following steps:
Utilization contains the raw material of organic silane, forms the gate insulating film of silicon oxide-containing by chemical vapour deposition (CVD); And
After forming described gate insulating film, illumination is mapped on the described gate insulating film, eliminating the carbon in the described gate insulating film,
Wherein, under 10 holders or lower decompression, or under the oxidizing atmosphere of atmospheric pressure, the described at least gate insulating film of described rayed 5 seconds to 5 minutes, so that the speed with 30 to 300 ℃ of per seconds makes the temperature of described gate insulating film be lifted to 1000 to 1300 ℃, the temperature of described gate insulating film descends with the speed of 30 to 300 ℃ of per seconds subsequently.
10. a method that forms semiconductor device comprises the following steps:
On dielectric substrate, form the Si semiconductor film;
With oxic gas the surface portion of described Si semiconductor film being carried out thermal oxidation, is 20 to 200 to form thickness in described surface portion
Figure C200610101420C0003165503QIETU
First silicon oxide layer;
Utilization contains the raw material of organic silane, comes to form second silicon oxide layer by plasma activated chemical vapour deposition on described first silicon oxide layer;
By the irradiation infrared light described second silicon oxide layer is carried out photo-annealing; And
On described second silicon oxide layer, form gate electrode,
Wherein, before forming described second silicon oxide layer, form described first silicon oxide layer,
Wherein, under 10 holders or lower decompression, or under the oxidizing atmosphere of atmospheric pressure, described at least second silicon oxide layer of described rayed 5 seconds to 5 minutes, so that the speed with 30 to 300 ℃ of per seconds makes the temperature of described second silicon oxide layer be lifted to 1000 to 1300 ℃, the temperature of described subsequently second silicon oxide layer descends with the speed of 30 to 300 ℃ of per seconds.
11. method as claimed in claim 10, wherein, described light also shines on the described semiconductive thin film.
12. method as claimed in claim 10, wherein said only halogen light.
13. method as claimed in claim 10 wherein, is carried out described step of thermal oxidation under 500 to 700 ℃ underlayer temperature.
14. method as claimed in claim 10, wherein, described photo-annealing is implemented by making described illumination be mapped to described at least first and second silicon oxide layers.
15. a method that forms semiconductor device comprises the following steps:
On substrate, form semiconductive thin film;
Make described semiconductive thin film crystallization;
After described crystallization steps, utilize the raw material that contain organic silane, on the semiconductive thin film of described crystallization, form silicon oxide film by plasma activated chemical vapour deposition;
After forming described silicon oxide film, infrared light is shone on the described at least silicon oxide film, to eliminate the carbon in the described silicon oxide film; And
On described silicon oxide film, form gate electrode,
Wherein, in the peripheral circuit region of liquid crystal apparatus, form described silicon oxide film at least,
Wherein, under 10 holders or lower decompression, or under the oxidizing atmosphere of atmospheric pressure, the described at least silicon oxide film of described rayed 5 seconds to 5 minutes, so that the speed with 30 to 300 ℃ of per seconds makes the temperature of described silicon oxide film be lifted to 1000 to 1300 ℃, the temperature of described silicon oxide film descends with the speed of 30 to 300 ℃ of per seconds subsequently.
16. a method that forms semiconductor device comprises the following steps:
On substrate, form semiconductive thin film;
Make described semiconductive thin film crystallization;
After described crystallization steps, utilize the raw material that contain organic silane, on the semiconductive thin film of described crystallization, form silicon oxide film by chemical vapour deposition (CVD);
Under 10 holders or lower pressure, infrared light is shone on the described at least silicon oxide film; And
On described silicon oxide film, form gate electrode,
Wherein, the described at least silicon oxide film of described rayed 5 seconds to 5 minutes, so that make the temperature of described silicon oxide film be lifted to 1000 to 1300 ℃ with the speed of 30 to 300 ℃ of per seconds, the temperature of described silicon oxide film descends with the speed of 30 to 300 ℃ of per seconds subsequently.
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