CN1338770A

CN1338770A - Manufacture of film semiconductor device

Info

Publication number: CN1338770A
Application number: CN01141002A
Authority: CN
Inventors: 宫坂光敏; 时冈秀忠; 小川哲也
Original assignee: Seiko Epson Corp; Mitsubishi Electric Corp
Current assignee: Seiko Epson Corp; Mitsubishi Electric Corp
Priority date: 2000-06-12
Filing date: 2001-06-12
Publication date: 2002-03-06
Anticipated expiration: 2021-06-12
Also published as: JP4290349B2; TW521434B; JP2002367904A; CN1218367C

Abstract

The invention relates to manufacturing an excellent polycrystalline thin film semiconductor device under a comparatively lower temperature. After formation of an amorphous semiconductor film, it is crystallized in the solid phase. Thereafter, the crystallized amorphous semiconductor film is partly fused through irradiation of a pulse laser which exhibits absorption coefficient in the amorphous silicon which is higher than that in the polycrystalline silicon.

Description

The manufacture method of thin-film semiconductor device

The present invention relates to form the technology that crystal properties reach the polycrystal semiconductor film of best excellence with Celsius approximately 600 following lower temperatures; Especially the relevant manufacture method of using this technology to make and significantly improve as the performance of semiconductor device of representative with polycrystalline SiTFT.

Can use general glass substrate Celsius 600 the degree following low temperature manufacturing with the situation of polycrystalline SiTFT (p-Si TFT) as the thin-film semiconductor device of representative under, the past is taked following manufacture method always.At first, on substrate, pile up the thick amorphous silicon film that becomes semiconductor film of 50nm with low pressure chemical gas phase method of piling (LPCVD method).Then, irradiation XeCl excimer laser (wavelength 308nm) makes polysilicon film (p-Si film) on this amorphous film., be absorbed into from the surface to 15nm because big respectively at the amorphous silicon of XeCl excimer laser and the absorption coefficient in the polysilicon so incide 9 one-tenth of laser on the semiconductor film to 0.139/nm and 0.149/nm.And the absorption coefficient in the amorphous silicon is littler by 7% than the absorption coefficient in the polysilicon.With chemical gaseous phase method of piling (CVD method) and physical vapor method of piling (PVD method) become the silicon oxide film of gate insulating film thereafter.Then, make gate electrode, constitute the field-effect transistor of forming by metal (gate electrode)-oxide-film (gate insulating film)-semiconductor (polysilicon film) (MOS-FET) with tantalum etc.At last on these film, pile up interlayer dielectric, after opening contact hole, implement wiring, finish thin-film semiconductor device with metallic film.

Yet in the thin-film semiconductor device manufacture method in the past, the excimer laser energy density is restive, even according to the change a little of energy density, semiconductor is membranous also can to demonstrate tangible deviation in same substrate.And, even if according to the threshold values of determining by thickness and corresponding hydrogen content irradiation energy density is strengthened a little, also major injury will take place on semiconductor film, cause the obvious decline of characteristic of semiconductor and job efficiency.Like this, in order in substrate, to obtain the polycrystal semiconductor film of homogeneous quality, must be with the density of the low setting laser energy of optimum value, therefore in order to obtain good polycrystal film, the energy density deficiency is also not all right.And, promptly use the optimum density irradiating laser, make the crystal grain that constitutes polycrystalline film do greatly also difficulty, residual many defectives in film.According to such fact, propose in order stably to make the thin-film semiconductor device of p-Si TFT etc. with existing manufacture method, and the electrical characteristic of the thin-film semiconductor device that can not make with reduction is the problem of cost.

According to the above-mentioned fact, its purpose is to provide a kind of manufacture method, and the cryogenic engineering below spending with Celsius 600 is the best thin-film semiconductor device of manufacturing property stably.

After of the present invention explaining the main points briefly, again the present invention and basic principle thereof are elaborated.

Thin-film semiconductor device manufacture method of the present invention, crystallinity semiconductor film based on the silicon (Si) that forms on substrate is used as active layer, it is characterized in that, comprise following operation: form semiconductor film, on substrate, form the silicon oxide film that becomes base protective film as required, at the amorphous semiconductor film of piling up on this base protective film or on the substrate based on silicon (Si); Solid-phase crystallization makes this amorphous semiconductor membrane crystallization obtain the solid state growth semiconductor film with solid state shape; Rayed, irradiated with pulse laser on the solid state growth semiconductor film that obtains like this obtains the crystallinity semiconductor film; At this moment the pulse laser wavelength that uses is as more than the 370nm, below the 710nm.The absorption coefficient of the polysilicon of light is bigger than the absorption coefficient of amorphous silicon like this.Also have, the invention is characterized in that pulse laser wavelength is more than the 450nm, below the 650nm.In view of the above, the absorption coefficient μ in the polysilicon of pulse laser _DSiFor from 10 ^-2Nm ^-1To 10-3nm ^-1Absorption coefficient μ in the polysilicon of so-called semiconductor thickness d (nm) and pulse laser _DSi(nm ^-1) better be to satisfy relational expression:

0.105μ _DSi ^-1＜d＜0.693μ _DSi ^-1。

Preferably satisfy relational expression:

0.405μ _DSi ^-1＜d＜0.693μ _DSi ^-1

In order to make the present invention adapt to LCD etc., wish that substrate has the transparency to visible light.And, use howsoever, wish that substrate is transparent for pulse laser substantially.The so-called transparent substantially pulse laser that means is absorption coefficient about below 1/10th of polysilicon at the absorption coefficient on the substrate, specifically, and the absorption coefficient μ of substrate _DSiBe 10 ^-4Nm ^-1Below.Usually, the formation of the amorphous semiconductor film of front comprises the accumulation operation according to chemical gaseous phase method of piling (CVD method).Especially low pressure chemical gas phase method of piling (LPCVD method) and even plasma chemical gas phase method of piling are applicable to the accumulation of amorphous semiconductor films in the chemical gaseous phase method of piling, and, can be described as the piling apparatus of desirable amorphous semiconductor film with high vacuum type low pressure chemical gas phase piling apparatus or high vacuum type plasma chemical gas phase piling apparatus.So-called high vacuum type low pressure chemical gas phase piling apparatus typically is meant such film formation device: the environment vacuum degree before semiconductor film is piled up becomes 5 * 10 ^-7Below the Torr,, also can make the concentration of oxygen atoms in the amorphous semiconductor film become 2 * 10 even amorphous semiconductor film forms with the following slow stackeding speed of 1.5nm/min ¹⁸Cm ^-3Below.Equally, so-called high vacuum type plasma chemical gas phase piling apparatus is typically such film formation device: the environment vacuum degree before semiconductor film is piled up becomes 1 * 10 ^-6Below the Torr,, also can make the concentration of oxygen atoms in the amorphous semiconductor film become 2 * 10 even the amorphous semiconductor film stackeding speed is below the 1nm/sec ¹⁶Cm ^-3Below.Shining under the situation of YAG2 ω laser on based on the semiconductor film of silicon, better is that the semiconductor thickness is below the above 165nm of 25nm, preferably below the above 95nm of 25nm.

The solid-phase crystallization operation is inserted the substrate that forms amorphous semiconductor film in the heat-treatment furnace, carries out under thermal equilibrium state substantially, or carries out with rapid thermal process apparatus.Under the situation of in heat-treatment furnace, carrying out, the heat treatment temperature solid-phase crystallization of doing below 700 more than 400 Celsius.

The ideal pulse optical maser wavelength of the rayed operation among the present invention is 532nm.Solid State Laser (Q switching Solid State Laser) high order harmonic component of the Q switching vibration of pulse laser is best.As Q switching Solid State Laser medium it is desirable to the mix crystallization of Nd ion and the crystallization of doping Yb ion, the glass of doping Nd ion, glass of doping Yb ion etc.Thereby, specifically, the Nd:YVO of second high order harmonic component (wavelength 532nm) of the Nd:YAG laser of Q switching vibration (being called for short YAG2 ω) and Q switching vibration ₄Second high order harmonic component of laser (wavelength 532nm), second high order harmonic component (wavelength 524nm) of the Nd:YLF laser of Q switching vibration, second high order harmonic component (wavelength 515nm) of the Yb:YAG laser of Q vibration etc. is used best as pulse laser.

In the rayed operation, the irradiation area on the semiconductor film on the solid state growth semiconductor film during irradiated with pulse laser is that width is W (μ m), and length is the linear to rectangularity slightly of L (mm).In irradiation area, the pulsed laser irradiation energy density distributes substantially in echelon at length direction.On the other hand, Width irradiation energy density is preferably substantially in echelon to becoming Gaussian function to distribute substantially.The irradiation area length L, it is desirable to more than 1000 more fortunately more than 100 the ratio (L/W) of W.The irradiation energy density greatest gradient value of pulsed laser width direction is 3mJcm more fortunately ^-2μ m ^-1More than.If the gradient maximum value position of the irradiation energy density of this pulsed laser width direction of getting and the peaked position of irradiation energy density of the pulsed laser width direction of getting are unanimous on the whole, be better for making good thin-film semiconductor device so.

At this moment, wish width W more than 1 μ m, below the 6 μ m.Pulse laser is radiated at Width at every turn on the solid state growth semiconductor film stagger irradiation area, finishes the irradiation of whole of substrate.The sense of current in the active layer when irradiation area Width during pulsed laser irradiation is finished the work with thin-film semiconductor device is parallel substantially.When laser radiation, some enforcement laser radiation operation under the state that is subjected to the pulsed laser irradiation below 80 times more than 10 times arbitrarily on the semiconductor film.The irradiation energy density of the solid state growth semiconductor film of pulse laser is to make at least more than the intensity of solid state growth semiconductor film surface melting, we can say the intensity that is more preferably the fusing more than 2/3rds that makes solid state growth semiconductor film thickness direction.Otherwise the upper limit of irradiation energy density is to make below the intensity that the part of solid state growth semiconductor film disappears, and it is desirable to make below the intensity that solid state growth semiconductor thickness direction melts fully.Specifically, using under the situation of wavelength for the light of about 532nm as pulse laser, the irradiation energy intensity on the pulse laser solid state growth semiconductor film is 100mJcm ^-2More than, 1500mJcm ^-2Below, be preferably 600mJcm ^-2More than, 1500mJcm ^-2Below, or 100mJcm ^-2More than, 850mJcm ^-2Below, 600mJcm preferably ^-2More than, 850mJcm ^-2Below.

The manufacture method of thin-film semiconductor device of the present invention, in the glass softening point temperature from Celsius 550 to 650 low like this thermal endurance glass substrate, or the semiconductor film of the crystallization that forms on the various transparent substrates of the such high-fire resistance glass substrate of quartz substrate etc. uses as active layer, it is characterized in that, comprise following operation: semiconductor film forms, on substrate, become the silicon oxide film of base protective film as required, at the amorphous semiconductor film of piling up to the substrate on this base protective film based on silicon; Solid-phase crystallization makes this amorphous semiconductor membrane crystallization under solid state shape, obtain the solid state growth semiconductor film; Rayed, pulse laser on the solid state growth semiconductor film that forms like this obtains the crystal semiconductor film; Its wavelength of the pulse laser that uses in irradiation process is more than 370nm, below the 710nm.Such light, the amorphous silicon absorption coefficient is greater than the absorption coefficient of polysilicon.As pulse laser best be second high order harmonic component of the Nd:YAG laser of Q switching vibration.

When the present invention was applied to LCD, substrate was for visible light printing opacity preferably, when beyond this, using best substrate at least paired pulses laser be printing opacity substantially.Specifically, the substrate absorption coefficient for pulse laser is below 1/10th of absorption coefficient of relative polysilicon as best conditions.This is because the present invention adopts strictness to be adjusted at the technology of the penetrance in the semiconductor film of pulse laser, so the absorption coefficient of the relative semiconductor film of laser absorption coefficient of substrate and insufficient little produces laser damage so on substrate.In situation described later, in order to obtain high-quality crystal semiconductor film, must make intensity and the bests such as wavelength, semiconductor thickness of pulse laser, adding substrate relative pulse laser must be printing opacity substantially.In fact, the pulse laser absorption coefficient of substrate is if below 1/10th of the absorption coefficient of semiconductor film, and the bed thickness that absorbs laser so in substrate is more than ten times of semiconductor thickness.With such substrate, light absorbing volume increases, so corresponding therewith thermal capacity also increases, becomes can suppress the rising of underlayer temperature certainly to a certain extent.In other words, not damage substrate and thin-film semiconductor device in order making, to make the thin-film semiconductor device of function admirable, substrate must satisfy above-mentioned optical characteristics condition.

In semiconductor film forms operation, at substrate to the amorphous semiconductor film of on the base protective film that forms in the substrate that forms on the substrate, piling up based on silicon.Can use with silicon fiml and germanium-silicon film (Si as semiconductor film _xGe _1-x: 0＜x＜1) be the semi-conducting material of representative, with silicon as its main composition element (the silicon atom constituent ratio is more than 80%).Substrate uses transparent alkali-free glass usually in LCD, or transparent crystal glass, also use the insulating properties substrate of quartz glass and pottery etc., if but substrate thermal endurance (softening point temperature under the glass substrate situation) Celsius more than 650, kind is not limit so.Under situation about except that high-purity quartz glass, using as substrate, on these substrate surfaces, make base protective film to semiconductor film, preferably pile up oxide-film 100nm～10 μ m.

Not only take the electrical insulating property of semiconductor film and substrate as the silicon oxide film of base protective film, or prevent that the impurity that substrate contains from sneaking into toward the semiconductor film diffusion, and make the purity at interface of substrate oxide-film and crystal semiconductor film all high.In the present invention, the semiconductor film of thin-film semiconductor device has the thickness of 10nm～200 μ m, and all scopes of the direction by the semiconductor thickness can be with that (being equivalent to the complete depletion-mode of SOI) becomes main object under the situation of distortion.In this case, the conductivity participation is ignored at the interface of the interface of gate insulating film and semiconductor film and base protective film and semiconductor film.Because silicon oxide film is can reduce the interface trap energy level greatly when becoming with interface that semiconductor film becomes, so be suitable for as base protective film certainly.On this base protective film, form semiconductor film.

Therefore, as base protective film the present invention require to use with the interface of semiconductor film on have 10 ¹²Cm ^-2The silicon oxide film of following interface energy level.Have again, in the present invention, compared with the prior art, because strong in the trend of semiconductor film bottom also heat, so, be easy to generate diffusion of impurities from substrate.In order to prevent this point, in order to make good semiconductor device with use high-purity semiconductor film, it is indispensable that the high silicon oxide film of density is used as base protective film in the present invention.Its liquid temperature of silicon oxide film like this is that 25 ± 5 ℃ of concentration are that the etching speed of 1.6 ± 0.2% fluorine hydrogen (HF) aqueous acid is below the 1.5nm/s.Usually, base protective film forms with plasma chemical gas phase method of piling (PECVD method) and low pressure chemical gas phase method of piling (LPCVD method), the such method of piling of sputtering method.To be particularly suitable for base protective film of the present invention in order making in all these, in the PECVD method, preferably to use electron cyclotron resonance PECVD method (ECR-PECVD method) and spiral PECVD method, remote control PECVD method.

And the general PECVD method of the frequency of industrial in order to use (13.56MHz) frequency and its integral multiple obtains being suitable for silicon oxide film of the present invention, uses TEOS (Si-(O-CH ₂CH ₃) ₄) and oxygen (O ₂) as raw material, as long as the flow set of oxygen is become the accumulation silicon oxide film more than 5 times of TEOS flow.Or use silane (SiH ₄) and nitrous oxide (N ₂O) as raw material, use helium (He) to the such inert gas of argon (Ar) as diluent gas, the ratio that makes the inert gas in the total gas couette is at (that is, the ratio of raw material is less than 10% in the total gas couette) more than 90%, as long as pile up silicon oxide film.At this moment, underlayer temperature is preferably in more than 28 degree Celsius.When substrate is made up of high-purity quartz, though share base protective film and quartz substrate is good, often make the surface state unanimity, in order to make semiconductor film quality fluctuations minimum, preferably form base protective film with said method.

On base protective film, pile up the semiconductor film that is in noncrystalline state.In the accumulation of semiconductor film, available plasma chemical gas phase method of piling (PECVD method) and low pressure chemical gas phase method of piling (LPCVD method), normal pressure chemical gas phase method of piling (APCVD method), the so various gas phase method of pilings of sputtering method, but, pile up this point easily from the high-purity semiconductor film, wherein especially low pressure chemical gas phase method of piling and plasma chemical gas phase method of piling are comparatively suitable.

Piling up with the amorphous silicon with low pressure chemical gas phase method of piling is that the silicon of representative is when being the amorphous semiconductor film of main body, preferably high order silane (Si _nH _2n+2N=2,3,4) use as one of unstrpped gas.Consider from price and fail safe, as high order silane, disilane (Si ₂H ₆) best.If disilane is suitable for low pressure chemical gas phase method of piling, so, under the low temperature below 425 degree Celsius, use the stackeding speed faster can produce the high-purity amorphous silicon film than 0.5nm/min.In order to obtain being suitable for high-quality amorphous semiconductor film of the present invention, the control of piling up temperature and speed is important.Pile up temperature below 430 degree Celsius, stackeding speed is the pressure in the time of must determining disilane flow and film forming under the above state of 0.6nm/min.Low pressure chemical gas phase method of piling carries out with high vacuum type low pressure chemical gas phase piling apparatus.The purity that this can improve semiconductor film makes because of impurity causes nuclei of crystallization generation and becomes minimum, and in the present invention, the crystallinity semiconductor film that obtains at last is into the state of high-purity and big crystal grain composition.Especially in the present invention, the nuclei of crystallization density that impurity is caused is minimum, in the solid-phase crystallization operation, obtain the polycrystalline solid state growth semiconductor film of bulky grain diameter, and, in the rayed operation, owing to also consider the situation that the semiconductor film thickness direction melts fully, if the nuclei of crystallization that impurity is caused take place minimum, use the laser that is suitable for melting crystal so, can promote to grow towards transverse crystallizing at the position of fusing fully.In prior art, owing to do not control impurity level and unaccommodated laser, so although Rong Hua position is made of micromeritics fully,, this obtains can both obtaining the polycrystal semiconductor film be made up of big crystal grain in complete melt portions in the present invention certainly.

So-called high vacuum low pressure chemical gas phase piling apparatus is meant such device, and the environment vacuum degree that was typically before semiconductor film is piled up is 5 * 10 ^-7Below the Torr,, also can make the concentration of oxygen atoms in the amorphous semiconductor film be lower than 2 * 10 even if amorphous semiconductor film is shaped with the stackeding speed that is lower than 1.5nm/min ¹⁶Cm ^-3The air-tightness excellence of such high vacuum type low pressure chemical gas phase piling apparatus film forming room, simultaneously, the exhaust velocity of film forming room has the high exhaust capacity more than 120sccm/mTorr (equalizing pressure that obtains when making inert gas flow into 120sccm film forming room is the exhaust velocity of 1mTorr), and this is desirable especially.In device with high like this exhaust capacity, use less than 1 hour short period and fully reduce degassing flow from substrate, keep high productivity ratio, can do the accumulation of high-purity semiconductive thin film.

Using Substrate Area to be 2000cm ²More than under the situation of certain large-sized substrate, low pressure chemical gas phase method of piling is difficult to adapt to.Under this situation, use high vacuum type plasma chemical gas phase piling apparatus when piling up amorphous semiconductor film.Typically be meant such film formation device, the environment vacuum degree before semiconductor film is piled up becomes 1 * 10 ⁶Below the Torr,, make the concentration of oxygen atoms in the semiconductor become 2 * 10 even if be the amorphous semiconductor film that the following low velocity of 1nm/sec is piled up with the stackeding speed of polycrystal semiconductor film ¹⁶Cm ^-3Below.As high vacuum plasma chemical gas phase piling apparatus, suitable at the plasma box PECVD device of the film forming room that carries out plasma treatment than its big other indoor setting.So-called plasma box PECVD device is a kind of like this hot wall type plasma chemical gas phase piling apparatus, make dual vacuum structure according to film forming room, have the effect that improves film forming room's vacuum degree, simultaneously, be heated into membranous wall face integral body, wall surface temperature is the same substantially with underlayer temperature when film forming.Whereby, make the impurity level of taking off by film forming room minimum, also confirm the effect of gas clean-up.

Environment vacuum degree when amorphous semiconductor film is piled up is improved like this, because the gas flow of taking off from wall reduces, so the purity of the semiconductor film of piling up improves, to thin film semiconductor device bring with low pressure chemical gas phase method of piling in front in the effect same that illustrates.Though the environment vacuum degree of high vacuum type plasma chemical gas phase piling apparatus is poorer than the environment vacuum degree of high vacuum type low pressure chemical gas phase piling apparatus, but, owing to the stackeding speed of semiconductor film is added more than 0.1nm/sec, so obviously reduce the impurity concentration in the semiconductor film.Use silane (SiH4) to disilane (Si2H6) in semiconductor film film forming unstrpped gas, the underlayer temperature during film forming is between Celsius 100 and 450 degree.Because hydrogen amount contained in the high amorphous semiconductor film of underlayer temperature reduces, so, can stably carry out the solid-phase crystallization operation of back.Underlayer temperature when it is desirable to the amorphous film accumulation is between 250 to 450 degree Celsius.If higher than 250 degree, contained hydrogen amount is reduced to below the 8atm% in amorphous film so, and the solid-phase crystallization operation can stably be carried out.If lower than 450 degree, the crystal grain that constitutes amorphous film so becomes big, and the crystal grain of the polycrystalline film that obtains during this amorphous film of crystallization also becomes big.Better is that non-crystal grain strengthens when 400 degree are following.When solid-phase crystallization, for prevent according to hydrogen from the peeling off of semiconductor film, contained hydrogen amount preferably is defined in below the 5al.m% in the semiconductor film, wherein the underlayer temperature during film forming be defined as Celsius more than 280, and, make film forming speed below 0.5nm/sec.Minimum for the impurity that enters in the semiconductor film, require film forming speed more than 0.1nm/sec.As a result, the underlayer temperature when the accumulation condition regulation of the best amorphous film of the present invention is piled up is between Celsius 280 to 400, and film forming speed is defined as between 0.1nm/sec and 0.5nm/sec.

Like this, after obtaining amorphous semiconductor film, under solid state shape, make this amorphous semiconductor membrane crystallization, form solid state growth polycrystal semiconductor film (solid-phase crystallization operation).The substrate that forms amorphous semiconductor film is inserted in the heat-treatment furnace crystallization of carrying out amorphous film under thermal equilibrium state roughly, or undertaken by rapid thermal process apparatus.Under the situation of carrying out, be that 400 degree Celsius carry out solid-phase crystallization to 700 degree conditions in heat treatment temperature with heat-treatment furnace.As consider productivity ratio, and heat treatment temperature is more than 500 degree Celsius preferably, from forming the angle of big crystal grain, 650 degree are better following.In the solid-phase crystallization of such temperature range, constitute the non-grain size of amorphous film and the grain size of formation polycrystalline film and concern greatly.In other words, when the amorphous film of forming by big non-crystal grain in above-mentioned heat-treatment temperature range with solid-phase crystallization, obtain the solid state growth polycrystalline film of forming by big crystal grain so.Therefore the growth of the restriction nuclei of crystallization when heat treatment temperature when doing crystallization is low obtains the polycrystalline film is made up of polycrystalline grain more, and still, the time of corresponding therewith crystallization end is also long.Heat treatment temperature is set between 500 to 650 degree Celsius low as far as possible, it is desirable to be set in the set point of temperature between 550 to 600 degree.This solid-phase crystallization is preferably in to contain from the oxidizing atmosphere of the oxygen of about 10ppm to about 10% and carries out.Form thin oxide-film on the semiconductor film surface according to such technology when the solid state growth.The formation of oxide-film causes the lattice mismatch of semiconductor atom group and oxide-film atomic group, when crystalline growth semiconductor film is related to strong stress.This strong stress promotes moving of semiconductor atom, and its result reduces proper product layer defects and twin crystal defective on the solid state growth polycrystalline film.In other words, make the threshold voltage of the thin-film semiconductor device that obtains at last and divide threshold voltage to descend, have influence on the thin-film semiconductor device that acquisition has good switching characteristic.

Like this, after obtaining many crystal semiconductors of solid state growth film, as irradiation process, irradiated with pulse laser on this solid state growth semiconductor film makes the surface melting of semiconductor film at least, carries out the crystallization again of polycrystal semiconductor film.Form to the maximum crystal grain of 5 μ m from 2 μ m by size of microcrystal according to the control membrance casting condition by the solid state growth polycrystalline film that the solid-phase crystallization operation obtains.Yet, these solid state growth films in crystal grain inside because of propagation (about 1 * 10 ¹⁸Cm ^-3) (Fig. 1 a) to contain lamination defective and twin crystal defective.Therefore, in the present invention, keep big crystal grain, these internal flaws are reduced as the rayed operation.In the rayed operation, the laser of radiation pulses vibration on the solid state growth polycrystalline film makes a part (mainly being the top section of the thickness direction of the semiconductor film) fusing (Fig. 1 b) of semiconductor film.At this moment the film thickness direction integral body of semiconductor film does not melt, and the part with the near interface of base protective film is stayed as original solid state growth polycrystalline film.So when cooling curing, this residual solid state growth film becomes the crystallization source, keeps the crystallization again of the crystallization particle diameter of original solid state growth polycrystalline film.Like this, again the crystal grain diameter after the crystallization also with initial the same size from 2 μ m to 5 μ m.On the other hand, the internal flaw of solid state growth film of the present invention is tended to the one-tenth branch parallel with substrate and is arranged, and, the temperature of the many crystalline film of residual solid state growth during melting crystal is owing to rise near silicon fusion temperature 1414 degree Celsius, so the crystal defect in the residual solid state growth polycrystalline film reduces in the melting crystal operation greatly.In addition, melting crystal depends on from 10 to 80 times repetition, and the defective in the residual solid state growth film obviously reduces along with the repetition of melting crystal.Like this, can form the few many conjunctivas of residual solid state growth of crystal defect, with these as the crystalline growth source, enter cooling procedure, so through Fig. 1 b partial melting state, intragranular most of defective can disappear, and its result can obtain the few many pn junction p ns film (Fig. 1 c) of big grain diameter internal flaw.

Though, use the laser of impulse hunting better as the material of irradiates light also available continuous oscillation.In the laser radiation of continuous oscillation, semiconductor film is in through under the several milliseconds of long molten states.Therefore, by gas phase impurity is sneaked in the film easily, or be easy to generate rough surface.To this, with the impulse hunting that each irradiation can be moved suitable distance, fusing time is below hundreds of microseconds, so can obtain the level and smooth polycrystallinity semiconductive thin film of high purity surface.

On semiconductor film, during irradiating laser, use the pulse laser of wavelength X at 370nm～710nm.In the amorphous silicon of these light and polysilicon in absorption coefficient as shown in Figure 2.The transverse axis of Fig. 2 is represented wavelength, and the longitudinal axis is represented absorption coefficient.Dotted line (Amorphous Silicon) expression amorphous silicon, solid line (Polysilicon) expression polysilicon.Recognize that from Fig. 2 absorption coefficient is being higher than in the polysilicon in the amorphous silicon in 370nm～710nm wavelength region may.In other words on the solid state growth polycrystal semiconductor film absorption coefficient of the amorphous silicon of irradiates light greater than the pulse laser of the absorption coefficient of polysilicon.For example, wavelength is the absorption coefficient μ of amorphous silicon of second high order harmonic component (being abbreviated as YAG2 ω light) of the Nd doping YAG of 532nm _USiAbsorption coefficient μ with polysilicon _DSiBe respectively:

μ _USi(YAG2ω)＝0.01723nm ^-1

μ _DSi(YAG2ω)＝0.00426nm ^-1

The absorption coefficient of amorphous silicon is bigger more than 4 times than the absorption coefficient of polysilicon.The solid state growth polycrystalline film is become to be grouped into noncrystalline by crystallised component from microcosmic.So-called crystallised component can be described as the fewer position of defective in intragranular lamination defective etc., is in the position of well-crystallized's state.On the other hand, so-called amorphous component can be described as the obviously disorderly position of mechanism's rule of seeing that the defective part in grain boundary and the crystal grain is graded, is in the position near the state of so-called amorphous.Carry out in the melting crystal of crystallization at irradiating laser, non-melt portion becomes the crystalline growth nuclear in the cooling curing process.Become crystalline growth nuclear if having the crystallised component of high structural order, the crystallization from this growth still becomes the well-crystallized film with structural order so.Otherwise, if the position of structural order disorder becomes crystalline growth nuclear, so since lamination defective etc. in the cooling curing process from this development, so the crystalline film of last acquisition becomes the low pledge that comprises defective etc.

Thereby, in order to obtain good crystalline film, do not make the crystallised component fusing in the many crystalline film of solid state growth, this is examined as crystalline growth, as long as preferential fusing amorphous component.In the present invention, the absorption coefficient of the amorphous silicon of irradiating laser is greater than the absorption coefficient of polysilicon, so amorphous component heats than preferential with crystallised component.As a result, the amorphous component of crystal boundary and rejected region melts easily, and one is in that the high-quality crystallised component of monocrystalline state substantially is residual not to be melted, and becomes the crystalline growth source, so form the few good crystal grain of crystal defect in cooling procedure.Like this, defective and azygous coupling are to significantly reducing, and crystal boundaries is arranged by the high corresponding crystal boundary of structural order also.This phenomenon produces as if the electrical characteristic according to semiconductor film, brings near the trap energy level density effect of forbidden band middle body that significantly reduces in the energy band diagram so.

And, the active layer (source region and drain region, channel formation region territory) of such semiconductor film as being used for thin-film semiconductor device, so, the close current value is little, show characteristic under the threshold values of pinnacle (branch valve oscillating quantity is little), can obtain the low transistor of threshold voltage.In prior art, why be not easy to produce good like this thin-film semiconductor device will owing to, do not have to use the laser in the melting crystal of solid phase polycrystalline film, have suitable wavelength, crystallised component is melted with noncrystalline composition.The effective function of the principle of the invention described here is that absorption coefficient in polysilicon is than the absorption coefficient (μ in the amorphous silicon _DSi/ μ _USi) produce when big.See that this ratio was big when Fig. 2 recognized optical wavelength 450nm～650nm.Thereby, we can say that in rayed operation of the present invention, desirable pulse laser wavelength is 450nm～650nm.At wavelength is absorption coefficient μ in the polysilicon of light of 450nm _DSiBe 1.127 * 10 ^-2Nm ^-1, wavelength is the absorption coefficient μ in the polysilicon of light of 650nm _DSiBe 8.9 * 10 ^-4Nm ^-1Therefore, illumination wavelength is the rayed operation of the pulse laser of 450nm～650nm, becomes use as the absorption coefficient μ of pulse laser in polysilicon _DSiProbably become 10 ^-3Nm ^-1～10 ^-2Nm ^-1Operation.

At last in order to obtain the well-crystallized semiconductor film, because the oscillatory stability of laser is most important, so preferably pulse laser forms with the solid-state light emitting element that Q switching vibrates.(in this application this being called Solid State Laser) is in existing excimer laser, the reasons such as indoor corrosion that produce in the inhomogeneities of the gas of indoor xenon of laser generation (Xe) and chlorine (Cl) etc. and gas difference itself or owing to halogen, the oscillation intensity deviation is about 5%, also confirms as the deviation about 5% of hunting angle.Because the deviation of oscillation angle is brought the deviation of irradiation area area, so the energy density on semiconductor bulk film surface (energy value of every cellar area) amounts to change more than 1% as a result, this is to hinder a major obstacle making defect semiconductor device aspect.

And the laser generation long-time stability also lack, and have caused the between-lot change of thin-film semiconductor device.To this, in Solid State Laser, have such problem, so laser generation is very stable, in the change of the energy density on semiconductor film surface (standard deviation of mean value than) relatively approximately less than 5%.In order more effectively to use the present invention, the laser energy density of requirement use on this semiconductor film surface changes the Solid State Laser less than 5%.Also have, Solid State Laser uses the effect that produces the batch variation minimum when thin film semiconductor is made, with from existing manufacture process of carrying out having liberated miscellaneous Gas Exchange operation semiconductor device continually, the productivity ratio when its effect causes thin-film semiconductor device to be made improves and the reduction of cost.What front wavelength and absorption coefficient required and the Solid State Laser requirement can be satisfied simultaneously is that neodymium (Nd) is added on yittrium oxide (Y ₂O ₃) and aluminium oxide (Al ₂O ₃) and double oxide in second high order harmonic component (YAG2 ω light, wavelength 532nm) of yttroalumite pomegranate red (Nd:YAG) laser that adds of neodymium.Thereby, best on semiconductor film the change of the energy density on semiconductor film surface in rayed operation of the present invention less than 5% YAG2 ω rayed.As the lasing medium of Q switching Solid State Laser preferably the mix crystallization of Nd ion and the crystallization of doping Yb ion, the glass of doping Nd ion, the glass of doping Yb ion etc.Therefore specifically, except YAG2 ω, second high order harmonic component (wavelength 532nm) of the Nd:YVO laser of Q switching vibration, second high order harmonic component (wavelength 524nm) of the Nd:YLF laser of Q switching vibration, second high order harmonic component (wavelength 515nm) of the Yb:YAG laser of Q switching vibration etc. is used best as pulse laser.

Therefore, in semiconductor film, absorbing light, its incident intensity decays with exponential function.Now, say that incident intensity is I _{＜0 〉}, establish from be x (nm) based on the surface distance in the polysilicon semiconductor film of silicon, in the intensity I of place x _{＜x 〉}For, among these, use absorption coefficient μ so _DSiThe time following formula set up:

I _{＜x 〉}/ I _{＜0 〉}=exp (μ _DSiX) ... formula 1 is at absorption coefficient μ _DSiBe 10 ^-3Nm ^-1Situation under and 10 ^-2Nm ^-1Situation under, and as the relation table of 1 formula being shown among Fig. 3 under the situation of second high order harmonic component (YAG2 ω light) of the best Nd:YAG laser of pulse laser of the present invention and under the prior art XeCl excimer laser situation.For silicon fiml is heated effectively, because the light of incident must have an appointment at least and 10% be absorbed by semiconductor film, so in Fig. 3, horizontal dotted line is drawn in 0.9 position that becomes its condition.And luminous intensity means the heat that in the same old way applies on silicon, so the Temperature Distribution in the silicon fiml when Fig. 3 also is illustrated in laser radiation.According to applicant's etc. research, in existing excimer laser radiation, the surface of semiconductor film is subjected to fierce damage, the residual inferior semiconductor layer in its underpart on the other hand on the one hand.The reason that good polycrystal semiconductor film can not obtain by prior art is the big temperature difference that exists between its semiconductor film surface and bottom.Do not damage on the surface, and substantially all being heated fusing more equably in semiconductor thickness direction is that the luminous intensity of semiconductor film bottom is that incident intensity is when over half approximately.The temperature difference of surface and bottom diminishes when satisfying this condition.So in Fig. 3, on 0.5 position of half that becomes the luminous intensity surface, also draw horizontal dotted line.Thereby, heat semiconductor film effectively based on silicon, and, damage on semiconductor film, do not caused, so the condition of carrying out crystallization well at whole thickness is to clip the 0.9 horizontal dotted line of Fig. 3 and the zone of 0.5 horizontal dotted line.Recognize prior art XeCl excimer laser since incident light nearly all absorbed by semiconductor film surface, so the semiconductor thickness that is suitable for the membranous improvement of semiconductor that produces according to laser radiation is limited to 1nm～4nm.Recognize this is undertaken by wide thickness scope that the many crystalline film of solid state growth melt crystallization again and with its membranous improvement under condition of the present invention.

In the present invention, in the semiconductor film zone of pulsed laser irradiation, the residual solid state growth polycrystalline film as thin as a wafer in the bottom of semiconductor film makes other position fusings, by residual solid state growth polycrystalline film growth crystallization (Fig. 1 b).On the other hand, the depth of fusion of semiconductor film is roughly determined according to the irradiating laser energy density.Yet, in each irradiation, also must change energy density no matter be what kind of laser aid.Use the present invention under the Solid State Laser situation to we can say that compared with the prior art laser generation is stable significantly, still unexceptional, should make the residual laser radiation of solid state growth polycrystalline film as thin as a wafer even apply, according to the variation a little of its energy, the complete molten state of semiconductor film melt-through also can take place according to certain probability basis.Therefore, no matter use such laser, crystallization is also grown along temperature gradient.Usually, the thickness of the semiconductor film that uses in the thin-film semiconductor device is about 30nm～200nm.As previously mentioned, in crystallization according to existing XeCl excimer laser, at about 4nm on semiconductor film surface with interior nearly all absorbing light, even molten state fully, also just the near surface heating causes, is created in the very steep temperature gradient of above-below direction (Fig. 4 a-1) in the semiconductor film of fusing.Therefore, the nuclei of crystallization mainly produce manyly on the downside interface, crystal grain from the bottom of semiconductor film to superficial growth.

Like this, finally constitute (Fig. 4 a-2) in the polycrystalline film that after the laser radiation of complete molten state, obtains by tiny crystal grain.(like this in prior art, from top to bottom because the small grains growth is many, so the existence of the nucleus that causes because of impurity in the semiconductor film does not become such major issue.) to this in the present invention, because irradiation has the laser of optimal absorption coefficient in melting crystal, so semiconductor film roughly is heated equably at film thickness direction.Its result, the end in the laser radiation zone, temperature gradient laterally produces (Fig. 4 b-1), and crystallization and its above-below direction are not as cross growth.Promptly change laser energy density,, produce and horizontally be grown in complete melting end and do not form small crystallization, the big crystal grain of the growth in generation (Fig. 4 b-2) even be in complete molten state.Even locate because of the above-below direction temperature difference is little beyond the end in irradiation area, the probability that the nucleus in the semiconductor film bottom produces also obviously reduces than existing complete molten state, and the crystal grain that on average constitutes polycrystal semiconductor film is bigger than the past.Even be in complete molten state like this, also may be in the present invention according to the long bigger crystal grain that obtains that grows wild.Promotion be not when changing like that to horizontal crystalline growth in the luminous intensity of top and the bottom, semiconductor film surface, and according to experiment, the luminous intensity of semiconductor film bottom is the about situation more than 1/3rd of incident intensity.Therefore, in Fig. 3, on long incidental condition 0.667 position of growing wild, also draw horizontal dotted line.Thereby, effectively to based on the heating of the solid state growth semiconductor film of silicon, and, also growing wild when long, longly produce crystal semiconductor film formation condition that big crystal grain forms and become the horizontal dotted line that is clipped in 0.9 among Fig. 3 and the zone in the 0.667 horizontal dotted line by growing wild.Certainly, owing to, except that temperature gradient described here, also must suppress the nuclei of crystallization, in the accumulations such as semiconductor film that form with base protective film and semiconductor film in the operation, also require aforesaid treatment according to impurity in order to strengthen crystal grain.

See that Fig. 3 recognizes, even absorption coefficient is 10 ^-3Nm ^-1～10 ^-2Nm ^-1, can not obtain the good crystallinity semiconductor film of gross thickness yet.For example, with YAG2 ω light (absorption coefficient μ _DSi=4.26 * 10 ^-3Nm ^-1) semiconductor film thickness that silicon fiml is done heating effectively is about 25nm when above, the semiconductor thickness that the undamaged whole thickness in surface is heated substantially equably is when 165nm is following.And, also be to be that 95nm is when following when melting fully at the generation long semiconductor film that keeps big crystal grain that grows wild.Thereby the thickness of best semiconductor film is 25nm～165nm during irradiation YAG2 ω laser on based on the semiconductor film of the solid state growth of silicon, is preferably 25nm～95nm.Wavelength and respective absorption coefficient in the polysilicon of the laser that uses like this, best semiconductor film thickness difference.Specifically, heat silicon fiml effectively, and in film thickness direction heating equably substantially, in formula 1, establishing semiconductor thickness x is d, then I with no damage on the surface _{＜d 〉}/ I _{＜o 〉}Be equivalent to the condition between 0.5 and 0.9.

0.5＜I _{＜d 〉}/ I _{＜o 〉}＜0.9 ... formula 2 use formulas 1 are separated formula 2 and are obtained relevant d (nm) and then obtain relational expression 3

0.105 μ _DSi ^-1＜d＜0.693 μ _DSi ^-1Formula 3 heats silicon fiml equally effectively, and the long I that keeps big crystal grain that grows wild when melting fully _{＜d 〉}/ I _{＜o 〉}Obtain following relational expression 4 in the time of between 0.667 and 0.9

0.405 μ _DSi ^-1＜d＜0.693 μ _DSi ^-1Absorption coefficient μ in many knots silicon of formula 4 semiconductor thickness d (nm) and the pulse laser that on this semiconductor film, shines _DSi(nm ^-1) satisfying described formula at 3 to 4 o'clock, be bound to obtain good crystalline semiconductor film, thus excellent thin-film semiconductor device also can be made certainly.

Consider the optical wavelength of light shown in Figure 2 and the relation of absorption coefficient, Fig. 5 refigure wavelength and based on the semiconductor thickness of silicon relation promptly has the relation of above-mentioned formula 3 and 4.According to the heating of the zone on the triangle label of Fig. 5 semiconductive thin film, the zone does not produce surface damage below the circle label, can exist at the semiconductor film thickness direction and heat all irradiation energy density more equably.And, owing to temperature difference about the zone under four jiaos of labels diminishes, so when melting fully, promote to the crystallization cross growth.In Fig. 5, also use straight line approximate circle label and four jiaos of labels respectively.Using these near linears, is under the situation of 440nm～710nm in the wavelength X of irradiating laser, if wavelength X and thickness d satisfy with

9.8 * 10 ^{α L2 (λ-440)}＜d＜53 * 10 ^{α H2 (λ-440)}Formula 5

Wherein, α L2=4.9 * 10 ^-3Nm ^-1

α H2=5.4 * 10 ^-3Nm ^-1Relational expression, so, heat semiconductive thin film efficiently, and it is roughly whole that no surface damage heats film equably in the direction of semiconductor thickness based on silicon.For example, under the situation that YAG2 ω is used as laser,, be 28nm～166nm. so satisfy the semiconductor thickness of this condition because wavelength is 532nm.If also have thickness d and wavelength X satisfy with

2.4 * 10 ^{α L2 (λ-440)}＜d＜32 * 10 ^{α M2 (λ-440)} Formula 6

Wherein, α L2=4.9 * 10 ^-3Nm ^-1

α M2=5.2 * 10 ^-3Nm ^-1Relational expression, so, heat semiconductor film efficiently based on silicon, and, when melting fully, also more desirably promote towards the crystallization cross growth.If under the situation that YAG2 ω is used as laser, so, when being 28nm～96nm, satisfies the semiconductor thickness this condition.

Equally, be under the situation of 370nm～440nm in the wavelength X of irradiating laser, if wavelength X and thickness d satisfy with

2.4 * 10 ^{α L1 (λ-370)}＜d＜11.2 * 10 ^{α H1 (λ-370)}Formula 7

Wherein, α L1=8.7 * 10 ^-3Nm ^-1

α M1=9.6 * 10 ^-3Nm ^-1Relational expression, heat semiconductive thin film so efficiently, and it is roughly whole that no surface damage heats film equably in the direction of semiconductor thickness based on silicon.If wavelength X and thickness d satisfy with

2.4 * 10 ^{α L1 (λ-370)}＜d＜6.0 * 10 ^{α M1 (λ-370)}Formula 8

Wherein, α L1=8.7 * 10 ^-3Nm ^-1

α M1=1.04 * 10 ^-2Nm ^-1Relational expression, heat semiconductive thin film so efficiently based on silicon, and, when melting fully, also promote better to the horizontal growth of crystallization.

In order to obtain good crystalline semiconductor film, the control of irradiation energy density is also very important on the semiconductor film of pulse laser.In other words, in order to make excellent semiconductor device, must be controlled at irradiation energy density in the proper range.At first,, the pulse laser of abundant intensity must be arranged for melting at least a portion of illuminated semiconductor film in order to promote melting crystal.This is that the lower limit of the proper range of the pulsed laser irradiation energy density on semiconductor film is (usually because the irradiation energy density of surface melting is equivalent to this value, so in this manual this is abbreviated as surface melting energy density (E _SM)), again according to experiment, make the best crystal semiconductor film that when fusing more than 2/3rds of the volume composition of illuminated semiconductor thickness direction obtain in pulsed laser energy density, therefore, the semiconductor device electrical characteristic excellence of such crystal semiconductor film as the active layer use.Like this, pulse laser of the present invention makes from disorderly part such as the structural order of the amorphous component that exists in the many crystalline film of solid state growth etc. and preferentially begins fusing, simultaneously, stay high-quality crystallised component selectively, also have, in order to promote evenly to melt in the cardinal principle of film thickness direction, repeat to make some times of operation of fusing more than 2/3rds, promptly use minimum irradiation number of times also can obtain good crystalline film.Therefore, preferably lower limit is the irradiation energy density that melts 2/3rds or more of volume composition that makes the film thickness direction of semiconductor film.(in this manual this irradiation energy density being called 2/3 melting capacity density (E2/3)).

Also there is higher limit in suitable irradiation energy density.When the laser energy density on semiconductor film surface is too high, because semiconductive thin film disappears, so laser energy density must (the irradiation energy density that will cause disappearance in this manual be disappearance energy density E less than the value that causes disappearance (Abrasion) certainly _Ab), this value becomes higher limit.And, even comprehensive disappearance does not take place,, the semiconductor film thickness direction (in this manual this irradiation energy density is abbreviated as complete melting capacity density (E when all being melted _CM)), be easy to take place the part disappearance of semiconductor film.This is the main cause that causes that when semiconductor device is made defective causes qualification rate to reduce, so this is very bad.Also have, when producing in the wide region at semiconductor film when melting fully, lost micro-crystallization with fusing fully with the long compensation of growing wild, therefore, the crystallinity semiconductor film that obtains after laser radiation is many by the composition change that micromeritics is formed.The electrical characteristic of the thin-film semiconductor device of Zu Chenging is ungood yet like this.Therefore, in order to make better thin-film semiconductor device, wish that in the lip-deep pulsed laser energy density of semiconductor film the value that only melts fully than semiconductor film thickness direction integral body is low.This becomes the limit value ideally for the suitable radiation energy density.

The result, be wavelength X that the Solid State Laser of doing impulse hunting below 370nm～710nm is radiated to have to satisfy and concerns to 8 formulas on the solid state growth polycrystal semiconductor film of silicon as main body of thickness from 5 formulas, make under the situation of thin-film semiconductor device, required shot densities becomes surface melting energy density (E on the semiconductor film of Solid State Laser _SM) above disappearance energy density (E _Ab) below.We can say and be more preferably surface melting energy density (E _SM) more than melt density (E fully _CM) below, or it is desirable to 2/3 melting capacity density (E _2/3) above melting capacity density (E fully _CM) below.Specifically, solid laser is second high order harmonic component of Nd:YAG laser, based on semiconductor thickness be at the silicon that forms on the transparent substrates YAG2 ω pulsed laser irradiation energy density (x axle) on the semiconductor film surface under the situation of 28nm～96nm and the fusing of illuminated semiconductor film volume composition (y axle) relation as shown in Figure 6.Recognize from Fig. 6, under such condition, because

E _SM＝100mJcm ^-2

E _CM＝850mJcm ^-2

E _Ab=1500mJcm ^-2So the irradiation energy density of 2/3rds fusings of the volume composition of illuminated semiconductor thickness direction becomes

E _2/3=600mJcm ^-2So we can say, the desirable irradiation energy density of the semiconductor film of YAG2 ω light is 100mJcm ^-2～1500mJcm ^-2100mJcm more preferably ^-2～850mJcm ^-2, or 600mJcm ^-2～1500mJcm ^-2, it is desirable to 600mJcm ^-2～850mJcm ^-2

Though rayed operation of the present invention comprises the crystal defect of volume, but irradiated with pulse laser on the solid state growth polycrystal semiconductor film that constitutes by big crystal grain, kept the crystal grain diameter of original solid state growth semiconductor film, and, so that crystal defect is reduced to purpose greatly.Therefore, preferably use the Solid State Laser of laser generation good stability, only to be radiated at absorption coefficient ratio big laser of absorption coefficient in crystallised component in the amorphous component than the low density energy density of complete melting capacity.If at this moment the relation of absorption coefficient and semiconductor film is set the best for, so, even fusing generation fully in a single day also can prevent because of the crystal grain controlled micro crystallization according to the long generation 1 μ m～3 μ m that grow wild.

In order to use effectively to this horizontal crystalline growth, except that aforesaid condition, the control of paired pulses laser radiation semiconductor film surface area shape also is important when being in complete molten state.For example, irradiation area is circular shown in Fig. 7 a, the situation (Fig. 7 b) that imagination reduces to outside laser intensity from the center.At this moment crystallization is because from the low outer circumferential high temperature center growth of temperature, so each crystal grain forms crystal grain till the ass ascends the ladder along with growth collision mutually.In addition, even the active region direction of getting semiconductor device is (if FET is source electrode, raceway groove, drain directions, if bipolar transistor is emitter, source electrode, collector electrode direction) any, certain crystal boundary how that occurs in the active region, do laser radiation with such irradiation area shape, even make thin-film semiconductor device, also can not obtain the semiconductor device of excellent quality.On the contrary in the present invention, irradiation area is set for width W (μ m), length L (mm) wire so that substantially rectangle (Fig. 8 a).

The laser radiation energy density is except irradiation area end (Fig. 8 b in the section of the length direction in irradiation area (A-A ' section of Fig. 8 a), near+the L/2) outer roughly distribute equally (Fig. 8 b), specifically, the central portion 90% of removing each end 5%, the length direction left and right sides with interior energy density change (to the ratio of the standard deviation of mean value) below 5%.On the other hand, the laser radiation energy density of the Width section in irradiation area (B-B ' section of Fig. 8 a) roughly in echelon (Fig. 9 a), or roughly become Gaussian function number form (Fig. 9 b).So-called Width section slightly becomes the Gaussian function number form, the laser intensity of Width (Fig. 9 b) in fact not only comprises with the approximate distribution shape that obtains of Gaussian function, but also comprise its intensity from center (0 point of Fig. 9 b) to near differentiable function end regions (Fig. 9 b ± W/2) distribution shape of minimizing smoothly.Show slightly at the width section that trapezoidal (under Fig. 9 situation a), preferably the Energy distribution variation is 30%～90% at the ratio of the central flat site below 5%.Therefore, near each end regions (Fig. 9 a ± W/2) becomes 5%～35% up and down.For example, be under the 100 μ m situations at width, middle section is 30 μ m～90 μ m, each end regions wishes it is 5 μ m～35 μ m up and down.Reduce defective effectively with the solid state growth semiconductor film, in order in a single day also to prevent controlled micro crystallization by the length of growing wild under the situation of fusing fully, the peaked position of preferably getting Width irradiation energy density gradient is unanimous on the whole with the peaked position of the irradiation energy density of getting Width.Rong Hua irradiation energy density is maximum position fully, and this place's irradiation energy density gradient is if maximum so, is in order to promote to grow wild length best.In the present invention like this, think that desirable Width section is that (Figure 10 is a) so that the distribution of the laser intensity of Fuji function type (Figure 10 b) for trapezoidal type.

In order when semiconductor film melts fully, to promote cross growth, except think LASER Light Source selection and be suitable for this inhibition of the film thickness direction crystalline growth of determining of semiconductor thickness, the control of the horizontal direction growth of film is also very important.Specifically, by make on the line so that the ratio (L/W) of width (abbreviation irradiating width) W of the length in rectangle laser radiation zone (it is long to be called for short irradiation) L and the scan method optimization of irradiation area, just might be to the direction crystalline growth that requires.At first, set ratio (L/W) to the irradiating width W of irradiation length L greater than 100.Should be such as fruit more than 100, so, the temperature gradient when each shines produces hardly at the length direction of irradiation area.Mainly produce at Width (B-B ' direction of Fig. 8 a).Its result, the length of growing wild of the Width one dimension to irradiation area is represented in crystallization.Irradiating width W is 5 μ m～500 μ m preferably, so if consider productivity ratio, this, it is desirable to more than 100 than (L/W), more than 1000.Then, make substrate and comprehensively scan at the each irradiation area that shines such shape that staggers of Width.Crystallization is in irradiating width direction growth when melting fully, so in case at the Width irradiation area that staggers, some crystal grain also connect at Width.Take such illuminating method, the crystal grain that constitutes the crystal semiconductor film of obtaining at last on average becomes big at the Width (B-B ' direction of Fig. 8 a) of irradiation.Therefore, get direction (if the MOSFET of the active region of thin-film semiconductor device in the irradiating width direction, then be source electrode, drain directions, if bipolar transistor, then be emitter, collector electrode direction), in active region (in the MOSFET channel formation region territory, or the emitter of bipolar transistor, base stage engaging zones and base region, and base stage, collector electrode engaging zones) crystal boundary do not exist, or even if the crystal boundary existence, its quantity is also very little, can realize excellent like this semiconductor device.

Each irradiation offset areas amount (abbreviating this as staggering amount) once irradiating long crystallite size (abbreviating this as crystalline growth size) of growing wild is preferably made following provisions during the scan laser irradiation area on substrate.The desirable amount of staggering is that the crystalline growth size is below half.Under these circumstances, even with the irradiation continuous several times of the laser energy density of complete molten state, crystallization is obviously strengthened to the probability that the active region direction of thin-film semiconductor device connects crystallization.Using under the situation of YAG2 ω light as lasing light emitter, the crystalline growth size is generally 1 μ m～3 μ m.Therefore, if the amount of staggering is below the 3 μ m, then crystallization may connect, if below 2 μ m, then its probability further increases.The crystalline growth size not only is defined as about 3 μ m usually, and it distributes according to certain probability function.If crystal size is also got big value usually, so, also can obtain same little value.Even little extremely about 1 μ m also can connect crystal grain reliably for the crystalline growth size, in other words,, set the amount of staggering and be about below the 1 μ m even in order also to connect crystal grain reliably to nearly all crystalline growth size value.It is desirable to below the 0.5 μ m.If the amount of staggering becomes below 0.1, even then make YAG2 ω light do impulse hunting with the high order harmonic component that reaches 20kHz, sweep speed is also slowly below 2mm/sec.In order to handle the large-sized substrate of so-called 500mm state, when considering productivity ratio, make sweep speed slowly to unrealistic below the 2mm/sec.Therefore, the lower limit of the amount of staggering is thought 0.1 μ m.If compared with connecting crystal productivity ratio is preferably considered, so the about 25 μ m of the higher limit of the amount of staggering.

In order to make excellent thin-film semiconductor device, also must make irradiation number of times (the being called for short the irradiation number of times) optimization of the pulse laser of any point on the irradiation semiconductor film.If inferior 10 times of irradiation, the ratio of defects in many crystal semiconductors of solid state growth film can not reduce so.On the contrary, if more than 80 times, can cause so by gas phase and in semiconductor film, sneak into impurity and the increase of semiconductor film surface roughness etc.Especially reach more than 200 times when shining number of times, then surperficial utmost point out-of-flatness utilizes such film, even make thin-film semiconductor device, does not also have satisfactory kinetic energy according to the gate leakage semiconductor device.In order to make the defective in effective reduction crystallinity semiconductor film, and keep the excellent thin-film semiconductor device in semiconductor film surface smoothly, the irradiation number of times under 10 times～80 times situations on substrate the scan laser irradiation area.In order to make excellent semiconductor device reliably, the irradiation number of times makes pulse laser scanning under 20 times～60 times situation.

Optimum value exists in the amount of staggering and the irradiation number of times, so determine best irradiating width W with these values.Irradiating width W is the long-pending of the amount of staggering and irradiation number of times.Represent with x (μ m) that in the amount of staggering when the irradiation number of times was represented with n time, irradiating width W (μ m) was:

W (μ m)=x (μ m) * n ... how the laser energy density of formula 9 and Width has nothing to do if distributing, irradiating width W is equivalent to laser energy density intensity becomes half width (the Full Width Half Macximum of point of maximum; FWHM).The lower limit of the amount of staggering ideal range is 0.1 μ m approximately, and the desirable minimum value of irradiation number of times is about 10 times, so desirable minimum irradiation width is about 1 μ m.On the contrary, the maximum of the amount of staggering is about 25 μ m, and the maximum of irradiation number of times is about 80 times, so the maximum illumination width is thought about 2000 μ m.As better irradiating width is to be about 0.5 μ m from the amount of staggering, and the about 5 μ ms of irradiation number of times in the time of about 10 times are about 3 μ m to the amount of staggering, between the about 240 μ m when the irradiation number of times is about 80 times.Be about 1 μ m from the amount of staggering, the irradiation number of times be about 20 o'clock or the amount of staggering be about 0.5 μ m, the irradiation number of times is about 20 μ m when being about 40 times, is about 2 μ m to the amount of staggering, being about between the 120 μ m when shining number of times and being about 60 times is called desirable irradiating width.In order to connect the long crystal grain that grows wild when melting fully in each irradiation, best irradiating width W becomes maximum and grows wild below long distance 2 times the 6 μ m of (3 μ m).

Desirable tranmitting frequency under the condition is that sweep speed becomes the value more than 2mm/sec like this.Relation is with the comprehensive amount of staggering x (μ m) between tranmitting frequency of pulse laser (Hz) and the sweep speed v (mm/sec).

Owing to show as:

V (mm/sec)=x (μ m) * 10 ^-3* f (Hz) ... so formula 10 desirable tranmitting frequency f (Hz) are:

F＞2 * 10 ³/ x ... formula 11 is because the better scope of the amount of staggering is 0.1 μ m～25 μ m, so according to formula 11, the better scope of tranmitting frequency is 0.08kHz～20kHz.Think to be more preferably 0.67kHz～20kHz, it is desirable to 1kHz～20kHz.According to formula 9 and formula 11, between tranmitting frequency f (Hz) and irradiation number of times (inferior) and irradiating width W (μ m), can see following relation:

F＞2 * 10 ³* n/x ... formula 12 is promptly set the condition that tranmitting frequency and irradiation number of times and irradiating width satisfy formula 12, when when semiconductor film becomes irradiated with pulse laser, makes the thin-film semiconductor device of superior quality with high efficiency.

The laser energy density gradient (abbreviating the energy density gradient as) of the Width that promotion is an irradiation area to a factor of the one dimension cross growth of crystallization Width when the melting fully of semiconductor film.Crystal growth rate u (x) during melting crystal becomes dT (x)/dx ratio with the temperature gradient of semiconductor film.

U (x)=kdT (x)/dx ... formula 13 still, k is a velocity constant here, T (x) is the temperature of the semiconductor film of the arbitrfary point x on the semiconductor film.If the fusing time of semiconductor film represents with tm, crystal size Lc is with the product representation of crystal growth rate and fusing time tm so.

Lc=u * t _m=kdT/dxt _m14 velocity constant k are constant for formula, and fusing time is also constant, so the temperature gradient of crystalline growth size and semiconductor film is proportional.On the other hand, the temperature of semiconductor film is because the energy density of a pulse laser is proportional, so, the result, crystalline growth size Lc and energy density gradient dE/dx are proportional.

Lc ∝ cE/dx ... formula 15 is in order to strengthen the crystalline growth size, certainly as long as strengthen the energy density gradient.Wait the experiment done according to applicant, use YAG2 ω light as the pulse laser melting crystal under the situation of the semiconductor film on the glass substrate, be about 3mJcm in maximum from the energy density gradient ^-2μ m ^-1Above 3.0mJcm ^-2μ m ^-1To 4.0mJcm ^-2μ m ^-1The time, become more than the 1 μ m to irradiating width direction crystalline growth size.And the maximum of energy density gradient is from about 10mJcm ^-2μ m ^-1To about 20mJcm ^-2μ m ^-1The time, be increased to about more than the 2 μ m to irradiating width direction crystalline growth size.And, be about 30mJcm in the maximum of energy density gradient ^-2μ m ^-1The time, become about 3 μ m to irradiating width direction crystalline growth size.Thereby,, the maximum of energy density gradient is set at 3mJcm for the crystal semiconductor film that obtains high-quality is made excellent semiconductor device ^-2μ m ^-1More than better, if at 10mJcm ^-2μ m ^-1～20mJcm ^-2μ m ^-1Between better, it is desirable to 30mJcm ^-2μ m ^-1More than.

According to the present invention, in order to obtain the crystal semiconductor film of low defective major diameter particle, make the semiconductor film accumulation operation of piling up amorphous semiconductor film and make the amorphous semiconductor film of such acquisition the bests such as solid-phase crystallization operation with the solid state shape crystallization, obtaining aspect the solid state growth semiconductor film that 2 μ m～5 μ m crystal grain constitute, by the rayed operation, with the Solid State Laser of oscillatory stability excellence, and with only shining the absorption coefficient laser bigger than the absorption coefficient in the crystallised component in the noncrystalline composition than the low density energy density of complete melting capacity.Like this, the crystal grain diameter of 2 μ m～5 μ m that maintenance solid state growth semiconductor film has reduces the defective in the crystallization greatly.Yet, even there is how stable laser, because each oscillation energy variable density also is completely melted with certain certain probability semiconductor film.In this case existing, though being the crystallite of tens of nm, average grain diameter produces, but, in the present invention, according to the relation that makes absorption coefficient and semiconductor thickness and wire so that slightly the energy density gradient of the existing rectangular irradiation area shape of journey, Width, the Width that is radiated at irradiation area suitably make the stagger scan method of appropriate amount of irradiation area at every turn, even dissolve fully in case produce, also can make the crystal grain of the 1 μ m～3 μ m length of growing wild, prevent controlled micro crystallization.So at least, the crystallization grain length for the irradiating width direction significantly increases, and the defective in the crystallization is few, surface smoothing, and the crystallinity semiconductor film of the excellence that acquisition purity is high is made better thin-film semiconductor device easily.

In above detailed description, make the big crystal semiconductor film of existing low-quality inconsistency can make even high-quality crystallinity semiconductor film according to the film build method of amorphous semiconductor film of the present invention and the method for crystallising in the solid state shape thereof and the rayed operation of carrying out thereafter.In view of the above, making with the thin-film transistor is that the electrical characteristic of the thin-film semiconductor device of representative obviously improves, and makes thin-film semiconductor device work with low-voltage simultaneously, and then, confirm stably to make the effect of such thin-film semiconductor device.

Fig. 1 is the figure of the explanation principle of the invention;

Fig. 2 is the figure of explanation optical wavelength and semi-conductive absorption coefficient relation;

Fig. 3 is the figure of luminous intensity relation in explanation semiconductor thickness and the film;

Fig. 4 is the figure of the explanation principle of the invention;

Fig. 5 is the wavelength of the explanation scope of the invention and the figure of semiconductor thickness relation;

Fig. 6 is the figure of the energy density and the volume composition relation of the present invention's one example;

Fig. 7 is the figure of explanation laser radiation shape;

Fig. 8 is the figure of explanation laser radiation shape of the present invention;

Fig. 9 is the figure of explanation laser radiation shape of the present invention;

Figure 10 is the figure of explanation laser radiation shape of the present invention;

Figure 11 is the figure of explanation manufacturing process of the present invention;

Figure 12～Figure 20 is the figure of explanation effect of the present invention.

With embodiment the present invention is described with reference to accompanying drawing.

Embodiment 1

Figure 11 a～d is manufacturing process's profile that expression forms the transistorized thin-film semiconductor device of MOS type electric field effect.In present embodiment 1, using glass deformation point temperature is that Celsius 750 glass ceramicses of spending are as substrate 101.But even if other substrate, if can bear maximum temperature in the thin-film semiconductor device manufacture process, its kind and size are not limit.At first, on substrate 101, pile up the silicon oxide film that becomes base protective film 102.On the semiconductor film of substrate, comprise under the situation that should remove unwanted impurity with ceramic substrate etc., before silicon oxide film is piled up as long as first base protective film of accumulation tantalum-oxide film and silicon nitride film etc.In originally executing example 1, on substrate 101, pile up the about 200nm of silicon oxide film as base protective film 102 with plasma chemical gas phase method of piling (PECVD method).Pile up silicon oxide film under the following conditions with CR-PECVD.

Silane (SiH ₄) flow ... 60sccm

Oxygen (O ₂) flow ... 100sccm

Pressure ... 2.40mTorr

Microwave (2.45GHz) output ... 2250W

Externally-applied magnetic field ... 875Gauss

Underlayer temperature ... 100 ℃

Film formation time ... the liquid temperature of 40 seconds these oxide-films is 25 ℃, and concentration is that the photoetching speed in 1.67% the etching acid aqueous solution is 0.5nm/s.

The pure property amorphous silicon film that is about 50nm with high vacuum type LPCVD device accumulation thickness on the base protective film that forms like this forms operation as semiconductor film.High vacuum type LPCVD device is a hot wall type, and volume is 184.5l, but the build-up areas gross area after substrate inserts is about 44000cm ²The maximum exhaust velocity of film forming room is 120sccm/mTorr.Piling up temperature is 425 ℃, before semiconductor film is piled up with the substrate heat treated of this temperature enforcement through 1 hour 15 minutes.In dry heat is handled, in being provided with the film forming room of substrate, import purity and be helium (He) 200 (sccm) more than 99.9999% and purity and be the hydrogen (H more than 99.9999% ₂) 100 (sccm), become film pressure to be maintained at about and be 2.5mTorr.After dried finished, the film forming room's environment vacuum degree before semiconductor film is piled up was 2.5 * 10 under 425 ℃ hygral equilibrium condition ^-7Torr.When amorphous silicon film is piled up, in film forming room, provide the silane (Si of purity more than 99.99% with the 200sccm flow ₂H ₆), pile up pressure and remain on 1.1Torr substantially.The stackeding speed of silicon fiml is 0.77nm/min (semiconductor film forms operation and finishes) under this condition.

Then on the amorphous semiconductor film that obtains like this, implement heat treatment, make amorphous film make solid-phase crystallization.Heat treatment atmospheric nitrogen be 99% and the mixed-gas atmosphere of oxygen 1% under carried out 24 hours with 600 ℃.According to this heat treatment, semiconductor film goes bad into polycrystalline state (end of solid-phase crystallization operation) from noncrystalline state.

Then, as the rayed operation second high order harmonic component of radiation pulses vibration Nd:YAG laser on the pure property of the solid state growth polysilicon film that obtains is implemented melting crystal in the solid-phase crystallization operation.Pulse laser time half-amplitude is about 60ns, and tranmitting frequency is 200Hz, and irradiation grows up to the 10mm wire and focuses on.Maximum for the energy density gradient of Width is 3.72mJcm ^-2μ m ^-1The each 2.5% ground scanning substrate that staggers that shines of this Line of light.The amount of staggering becomes 6.75 μ m, is subjected to about 40 laser radiations on the semiconductor film more arbitrarily.The laser radiation energy density is 700mJcm ^-2Change for the mean value of the irradiation energy density on semiconductor film surface is about 4%.Only make the most surperficial energy density of the semiconductor film of 50nm be about 100mJcm in the YAG2 ω laser that in present embodiment 1, uses ^-2, owing to make the energy density of fusing fully be about 850mJcm ^-2So about 80% of semiconductor film is melted.The crystal silicon film of such acquisition is implemented figure processing, form semiconductor film island 103.The scanning direction almost parallel of transistorized source-drain electrode direction and YAG2 ω laser (end of rayed operation).(Figure 11 a).

Below, under the state that covers the semiconductor film island 103 of having done figure processing, form silicon oxide film 104 with the CR-PECVD method.This silicon oxide film plays the gate insulator membrane interaction of semiconductor device.The condition that forms the silicon oxide film of gate insulating film shortened into 24 seconds except that the accumulation time, was the same with the accumulation condition of the silicon oxide film of base protective film.But, learn before the silicon oxide film accumulation, in the CR-PECVD device, on substrate, shine oxygen plasma, form the low-temperature plasma oxide-film at semiconductor surface.The plasma oxidation condition is as follows:

Oxygen (O ₂) flow ... 100sccm

Pressure ... 1.85mTorr

Microwave (2.45GHz) output ... 2000W

Externally-applied magnetic field ... 875Gauss

Underlayer temperature ... 100 ℃

Processing time ... 24 seconds

Form the oxide-film that is roughly 3.5nm according to plasma oxidation on the semiconductor film surface.After the oxygen plasma irradiation, keep vacuum continuously and pile up oxide-film.Thereby the two forms the silicon oxide film that becomes gate insulating film by plasma oxidation film and gas phase accumulating film, and its thickness is 119nm.The accumulation of the gate insulating film of finishing like this (Figure 11 b).

Then, form grid 105 according to metallic film with sputtering method.Underlayer temperature when sputter is 150 ℃.In present embodiment 1, tantalum (Ta) with the α structure with 750nm thickness is made grid, the sheet resistor of this grid is that 0.8 Ω/ follows, then grid is made mask, clamp-on the foreign ion 106 that becomes the alms giver or led, to the grid self-adjusting make source, drain region 107 and channel formation region territory 108.In present embodiment 1, make the cmos semiconductor device.When making nmos pass transistor, after aluminium (Al) coverlay film PMOS transistor portion, be chosen in the hydrogen phosphide (PH of 5% concentration dilution in the hydrogen ₃) as impurity element, will comprise that with accelerating voltage 80kV total ion of hydrogen is with 7 * 10 ¹⁵Cm ^-2Concentration clamp-on source, the drain region of nmos pass transistor.On the contrary, when making the PMOS transistor, cover after the nmos pass transistor portion, be chosen in the borane (B of 5% concentration dilution in the hydrogen with the aluminium film ₂H ₆) as impurity element, will comprise that with accelerating voltage 80kV total ion of hydrogen is with 5 * 10 ¹⁵Cm ^-2Concentration clamp-on the transistorized source of PMOS, the underlayer temperature of drain region (Figure 11 c) when clamp-oning is 300 ℃.

Then, use the PECVD method with TEOS (Si-(OCH ₂CH ₃) ₄) and oxygen as unstrpped gas.Underlayer temperature is 300 ℃ and piles up interlayer dielectric 109.Interlayer dielectric is made up of silicon dioxide film, and its thickness is roughly 500nm.After interlayer dielectric is piled up, have the impurity element activate of adding in the shrink fit of interlayer dielectric and source, the drain region simultaneously, in the environment of 300 ℃ of blanket of nitrogen, apply 4 hours heat treatment.Open the contact cave at last, be 180 ℃ with sputtering method regulation substrate temperature and pile up aluminium, connect up and finish thin film semiconductor's body device.(Figure 11 d).

Measure the transmission characteristic of the thin-film semiconductor device of making like this.The length and the width in the channel formation region territory of the semiconductor device of measuring are respectively 10 μ m, measure at ambient temperature.Example is illustrated among Figure 12.The mobility of obtaining with the zone of saturation of the Vds=8V of nmos pass transistor (saturated mobility) is 333cm ²V ^-1S ^-1, threshold voltage is 1.23V, sub-valve swing (サ Block ズレ-シュホ Le De スイ Application ゲ) is 0.206V, is 8.56 * 10 by threshold voltage and the flat energy principal mode trap energy level density of obtaining that is subjected to voltage ¹⁰Cm ^-3And, be 2.96 * 10 with the firing current of Vds=Vgs=4V definition ^-5A, on the other hand, Vds=4V, the close current of Vgs=0V becomes 2.19 * 10 ^-12A, only become with gate voltage 4V modulation obtain the above on-off ratio of 7 figure places the N type thin-film semiconductor device of excellence.Equally, the saturated mobility of the transistorized Vds=-8V of PMOS is 77cm ²V ^-1S ^-1, threshold voltage is 1.88V, sub-valve swing is 1.56 * 10 for 0.222V by threshold voltage and the flat energy donor-type trap energy level density of obtaining with voltage ¹⁶Cm ^-3

Also have, the firing current that defines with Vds=Vgs=-4V is 4.61 * 10 ^-6A, on the other hand, Vds=-4V, the close current of Vgs=0V becomes 2.10 * 10 ^-12A, only become with gate voltage 4V modulation obtain the above on-off ratio of 6.3 figure places the P type thin-film semiconductor device of excellence.The characteristic of these semiconductor device no change almost in substrate can balancedly be made high-performance semiconductor device.On the contrary, in prior art, in piling up the comparative example of amorphous silicon film with the excimer laser crystallization, the saturated mobility of nmos pass transistor is 33cm ²V ^-1S ^-1, threshold voltage is 3.70V, and sub-valve swing is 0.646V, and being subjected to principal mode trap energy level density is 2.65 * 10 ¹⁶Cm ^-3The transistorized saturated mobility of PMOS is 16cm ²V ^-1S ^-1, threshold voltage is-7.06V, and sub-valve swing is 0.617V, and donor-type trap energy level density is 6.55 * 10 ¹⁶Cm ^-3Resemble shown in this example, according to the present invention, in the total high mobility of two kinds of semiconductor device of N type and P type, have low valve valve voltage, and, to be low to moderate the operation below 600 ℃, can easily easy and stably make the fabulous thin-film semiconductor device of expressing precipitous sub-valve characteristic.Especially as recognizing by sub-valve oscillating quantity, its effect is great, obviously reduce near trap energy level density of forbidden band middle body and the level density that is subjected to principal mode and donor-type trap energy level density, might become the low voltage drive of the circuit that uses thin-film semiconductor device.And, in prior art,, think that advantage according to the present invention is that high mobility and low valve valve voltage and low trap energy level density realize simultaneously though big more threshold voltage of mobility and trap energy level density are also long-range.

Embodiment 2

Second high order harmonic component of the impulse hunting Nd:YAG laser except be radiated at the rayed operation on semiconductor film in, other manufacturing processes and embodiment's 1 is identical, can make thin-film semiconductor device like this.In present embodiment 2, has only YAG2 ω pulse laser that the wire of width 270 μ m length 10nm focuses in the Width of the each irradiation ratio that staggers, different with 2 of laser radiation energy densities on the semiconductor film and embodiment 1.Linear laser staggers in each irradiating width direction, and ratio selects 10%, 5%, 2.5%, 1.67% 4 kind of level.In view of the above, be subjected to arbitrarily a bit about 10 times, 20 times, 40 times, 60 times laser radiation respectively on the semiconductor film.Laser radiation energy density on the semiconductor film is changed to 400mJcm ^-2～800mJcm ^-2The maximum of laser energy density gradient proportional with it is changed to 1.99mJcm ^-2μ m ^-1～3.97mJcm ^-2μ m ^-1Identical with embodiment 1, the variation of the mean value of the YAG2 ω rayed energy density on semiconductor film surface is about 4%, E relatively _SMBe about 100mJcm ^-2, ECM is about 850mJcm ^-2

The electrical characteristic of the thin-film semiconductor device of making like this is as extremely shown in Figure 20 from Figure 13.The length in the channel formation region territory of electrical characteristic and width are all obtained by the linear current of Vds=± 0.1 transistor of 10 μ m, thereby the mobility shown in the present embodiment 2 is the mobility of electric field effect.And, 4 transistorized mean values that each value representation manufactures under each condition.The irradiation energy density on any YAG2 ω photosemiconductor film of the transverse axis of these figure (x axle) expression surface, the longitudinal axis (y axle) is represented corresponding electrical characteristic.And, for reference, at 0mJcm ^-2Expression does not apply the transistorized result that YAG2 ω rayed is used the solid state growth polycrystalline film on the position.

Figure 13 and Figure 14 represent the sub-valve swing of NMOS and PMOS.Irradiation energy density is in case surpass 600mJcm ^-2The time, in case when promptly the volume composition of the thickness direction of semiconductor film was melted more than 67%, then characteristic was improved rapidly under the threshold values, the sub-valve oscillating quantity of NMOS, PMOS represents to reach the following excellent value of 0.3V.The excellent value this point that expression is not limited in insulator film thickness arrival 119nm means, near the trap energy level density (dark trap energy level density) that is positioned at the forbidden band central authorities of energy band diagram table of the crystallinity semiconductor film that obtains is minimum, prove the crystal defect minimizing of wrong coupling equity in rayed operation of the present invention.And the energy density range expansion of expression superperformance is to melting about 800mJcm before fully ^-2Irradiation number of times even also see effect 10 times, but from 20 times to 60 times under the threshold values characteristic represent especially excellent value.

Figure 15 and Figure 16 represent with threshold voltage and flat energy definite YAG2 ω laser energy density dependence that is subjected to principal mode trap energy level number and donor-type trap energy level number with voltage.The same trend of Figure 13 and Figure 14 is identified, in case the fusing more than 67% of the volume composition of semiconductor thickness direction, then two trap energy level numbers obviously reduce.This means, capture type level density (shallow acceptor type trap energy level density) and minimum near the donor-type trap energy level density (shallow donor's type trap energy level density) of valence band near the principal mode that is subjected to of conduction band in the forbidden band.In rayed operation of the present invention, prove that effectively the crystal defect of lamination defective and twin crystal etc. reduces.Equally, Figure 17 and Figure 18 represent the threshold voltage obtained by the linear current of NMOS and PMOS, and under the situation of the fusing more than 67% of the volume composition of the thickness direction of semiconductor film, how the conductive-type transistor threshold voltage reaches about 2V then is suitable for practicality.The same with characteristic under the threshold values, shine number of times even also see effect 10 times, but preferably reduce shallow trap energy level density or reduce threshold voltage from 20 times to 60 times.

Figure 19 and Figure 20 are the figures of the relevant field effect mobility of obtaining by the linear current of NMOS and PMOS.When irradiation energy density surpasses about 600mJcm ^-2The time, promptly when the fusing more than 67% of the volume composition of semiconductor film thickness direction, NMOS and PMOS obtain very large mobility.Under the few situation of intragranular defective, mobility is all very strong with the crystal grain diameter correlation aspect the theory experiment.Thereby Figure 19 and Figure 20 mean that if make thin-film semiconductor device according to the present invention, the crystal semiconductor film is by the bulky grain diameter so, and the crystal grain of low defective constitutes.The irradiation number of times obtains high mobility in wide energy density scope in the time of 40 times～60 times.

Shown in present embodiment 2, when the fusing more than 67% of the volume composition of the thickness direction of semiconductor film, can be easy to make the thin-film semiconductor device more excellent than the past, when the irradiation number of times is 20 times～60 times, trap energy level density significantly reduces, should this can understand when the irradiation number of times is 40 times～60 times the excellent effect that produces low valve valve voltage and high mobility and deposit.

As mentioned above, the membrane according to the invention method, semi-conductor device manufacturing method, utilization can be used the K cryogenic treatment of inexpensive glass substrate, can be easily and stably make high performance thin-film semiconductor device.Therefore, under the situation in the manufacturing that the present invention is applied to active (ァ Network ティ Block) array liquid crystal display, can easily, stably make large-scale high-quality LCD.Also have under the situation that is applied to other electronic circuits manufacturings, also can easily, stably make high-quality electronic circuit.

Claims

1. thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Form semiconductor film, on substrate, pile up amorphous semiconductor film based on silicon (Si);

Solid-phase crystallization makes this amorphous semiconductor membrane crystallization obtain the solid state growth semiconductor film with solid state shape;

Rayed, irradiated with pulse laser on this solid state growth semiconductor film obtains the crystallinity semiconductor film;

This pulse laser wavelength is 370nm～710nm.

2. method according to claim 1 is characterized in that, the wavelength of described pulse laser is 450nm～650nm.

3. method according to claim 2 is characterized in that the wavelength of described pulse laser is about 532nm.

4. according to claim 1,2 or 3 described methods, it is characterized in that described pulse laser is the high order harmonic component of the Solid State Laser of Q switching vibration.

5. according to claim 1,2 or 3 described methods, it is characterized in that described pulse laser is the high order harmonic component of the crystallization of Nd ion doping as the Solid State Laser of the Q switching vibration of lasing medium.

6. method according to claim 1 is characterized in that, described pulse laser is second high order harmonic component of the Nd:YAG laser of Q switching vibration.

7. method according to claim 1 is characterized in that, described pulse laser is second high order harmonic component of the Nd:YVO laser of Q switching vibration.

8. according to each described method in the claim 1 to 8, it is characterized in that the irradiation energy density on the described solid state growth semiconductor film of described pulse laser is the intensity that is higher than the surface melting at least that makes this solid state growth semiconductor film.

9. according to each described method in the claim 1 to 8, it is characterized in that the irradiation energy density on the described solid state growth semiconductor film of described pulse laser is the intensity that is higher than about 2/3rds fusings of the thickness that makes this solid state growth semiconductor film.

10. according to each described method in the claim 1 to 9, it is characterized in that the irradiation energy density on the described solid state growth semiconductor film of described pulse laser is to be lower than the intensity that this solid state growth semiconductor film part is disappeared.

11., it is characterized in that the irradiation energy density on the described solid state growth semiconductor film of described pulse laser is to be lower than the intensity that this solid state growth semiconductor film is melted fully at thickness direction according to each described method in the claim 1 to 10.

12. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Rayed, illumination wavelength is about the 532nm pulse laser on this solid state growth semiconductor film, obtains the crystallinity semiconductor film;

Irradiation energy intensity on this solid state growth semiconductor film of this pulse laser is 100mJcm ^-2～1500mJcm ^-2

13. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Irradiation energy intensity on this solid state growth semiconductor film of this pulse laser is 600mJcm ^-2～1500mJcm ^-2

14. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

The irradiation energy intensity that this solid phase of this pulse laser is given birth on the K semiconductor film is 100mJcm ^-2～850mJcm ^-2

15. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Irradiation energy intensity on this solid state growth semiconductor film of this pulse laser is 600mJcm ²～850mJcm ^-2

16., it is characterized in that described solid-phase crystallization operation is to insert heat-treatment furnace at following described substrate of thermal equilibrium state substantially according to each described method in the claim 1 to 15.

17. method according to claim 16 is characterized in that, described heat treatment temperature is 400～700 ℃.

18., it is characterized in that described solid-phase crystallization operation is carried out according to each described method in the claim 1 to 15 in rapid thermal process apparatus.

19. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

The absorption coefficient of this pulse laser amorphous silicon is bigger than the absorption coefficient of polysilicon.

20. method according to claim 19 is characterized in that, the irradiation area on the described solid state growth semiconductor film of described pulse laser Cheng Kuanwei W (μ m) length substantially is L (mm) rectangle.

21. method according to claim 20 is characterized in that, on described irradiation area, the irradiation energy density of the described pulse laser of described length direction is scattered in trapezoidal substantially.

22., it is characterized in that on described irradiation area, the irradiation energy density of the described pulse laser of described width degree direction is scattered in trapezoidal substantially according to each described method in the claim 20 to 21.

23., it is characterized in that described length L is more than 100 to described width W than (L/W) according to each described method in the claim 20 to 22.

24., it is characterized in that described length L is more than 1000 to described width W than (L/W) according to each described method in the claim 20 to 23.

25., it is characterized in that the greatest gradient value of the irradiation energy density of the described Width of described pulse laser is greater than 3mJcm according to each described method in the claim 20 to 24 ^-2μ m ^-1

26. according to each described method in the claim 20 to 25, it is characterized in that, obtain described pulse laser described Width the irradiation energy density gradient peaked position and to obtain the peaked position of irradiation energy density of this Width of this pulse laser unanimous on the whole.

27., it is characterized in that described width W is 1 μ m～6 μ m according to each described method in the claim 20 to 26.

28. according to each described method in the claim 20 to 27, it is characterized in that, be radiated at the Width described irradiation area that staggers and carry out at every turn.

29., it is characterized in that the sense of current in the active layer of described Width and thin-film semiconductor device is parallel substantially according to each described method in the claim 2 to 10.

30., it is characterized in that illuminated 10 times～80 subpulse laser of any point on the described semiconductor film according to each described method in the claim 19 to 29.

31. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Form semiconductor film, form the amorphous semiconductor film based on silicon (Si) on substrate, its thickness is d (nm);

Rayed is radiated at the absorption coefficient μ in the polysilicon on this solid state growth semiconductor film _DSiBe 10 ^-3Nm ^-1～10 ^-2The pulse laser of nm-1;

This thickness d and this absorption coefficient μ _DSiSatisfy following relational expression:

0.105·μ _DSi ^-1＜d＜0.693·μ _DSi ^-1

32. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Rayed is radiated at the absorption coefficient μ in the polysilicon on this solid state growth semiconductor film _DSiBe 10 ^-3Nm ^-1～10 ^-2Nm ^-1Pulse laser;

0.405·μ _DSi ^-1＜d＜0.693·μ _DSi ^-1

33., it is characterized in that described substrate is transparent according to claim 31 or 32 described methods.

34. a thin-film semiconductor device manufacture method is used the crystallinity semiconductor film based on the silicon (Si) that forms on substrate as active layer, it is characterized in that, comprises following operation:

Form semiconductor film, form the amorphous semiconductor film based on silicon (Si) on substrate, its thickness is 25nm～165nm;

Rayed, second high order harmonic component of irradiation Nd:YAG laser on this solid state growth semiconductor film.

35. method according to claim 34 is characterized in that, the thickness of described semiconductor film is 25nm～95nm.