CN101079432A - Display device - Google Patents

Abstract

A display including a driving substrate provided, arrayed thereon, with a plurality of pixel electrodes and thin film transistors for driving the pixel electrodes. Each the thin film transistor includes a semiconductor thin film having an active region made to be polycrystalline by irradiation with an energy beam, and a gate electrode provided so as to cross the active region, and in a channel part of the active region overlapping with the gate electrode, the crystal state is varied periodically along the channel length direction, and substantially the same crystal state crosses the channel part.

Description

Display unit

The cross reference of related application

The present invention comprises and Japanese patent application JP 2006-344131 that submits to Japan Patent office on December 21st, 2006 and the relevant theme of submitting to Japan Patent office on May 25th, 2006 of Japanese patent application JP 2006-144847, and its full content is hereby expressly incorporated by reference.

Technical field

The present invention relates to a kind of display unit, particularly, relate to a kind of display unit that thin-film transistor is made as the switch element of pixel electrode and carries out active matrix (active matrix) demonstration.

Background technology

In the planar display as luminescent device, thin-film transistor (TFT) is used as the switch element of the Active Matrix LCD At of carrying out a plurality of pixels at liquid crystal indicator and use organic electroluminescence device.Thin-film transistor comprises polysilicon (poly-Si) is used for the TFT (poly-Si TFT) of active area and the TFT (amorphous Si TFT) that amorphous silicon (amorphous Si) is used for active area.

The carrier mobility of multi-crystal TFT is than high about 10 to 100 times of non-crystalline silicon tft, and has less ON (conducting) electric current deterioration.Therefore, multi-crystal TFT has the very excellent characteristic as the switch element composition material.

For the technology of making multi-crystal TFT, developed so-called low temperature polycrystalline silicon and handled, wherein, by utilizing K cryogenic treatment to make the amorphous silicon membrane multiple crystallization generally not being higher than under 600 ℃ the temperature, thereby realize the reduction of substrate cost.For example, in the low temperature polycrystalline silicon that uses excimer laser is handled, by the laser beam that is configured as wire amorphous silicon membrane is carried out pulse irradiation the mobile point of irradiation in ground the time on one point, make continuous point of irradiation major part overlap each other, thereby shine 10～20 times by the same section of laser beam with amorphous silicon membrane.This feasible polycrystal that can on the whole zone of active area, obtain uniform particle diameter.

Another example as the low temperature polycrystalline silicon processing, a kind of method has been proposed, wherein, the continuous laser beam irradiation amorphous silicon membrane that at the uniform velocity mobile point of irradiation, obtains by higher harmonics from the YAG laser, make irradiation energy constant, thereby formation crystal region, and carrying out one patterned makes the active area do not have the zone of crystal boundary to become thin-film transistor (disclose 2003-77834 number (particularly with reference to the Japan Patent as patent documentation 1 reference hereinafter, 0091～0092 section, and 0169 section)).

In addition, as the method that is used for limiting the width of crystal cross growth by the multistage irradiation of using mask, Columbia Universities etc. have proposed continuous transverse crystallizing (SLS) technology (with reference to hereinafter as the A.T.Vouysas of non-patent literature 1 reference, A.Limonov, and J.S.Im, " Journal of Applied Physics " (2003), Vol.94, pp.7445～7452).

Summary of the invention

In recent years, in above-mentioned planar display, the development with display unit of high frame rate is a purpose with further raising animated characteristics and contrast-response characteristic.In addition, also begun to develop the novel display unit of the automatic luminescent device of use such as organic EL device.Along with these development, flow through the development that does not also reduce characteristic and demonstrate the very for a short time thin-film transistor that departs from of switch element characteristic suddenly as the big electric current of the pixel electrode switching element that can tackle these display unit demands even need.

The significant advantage that the above-mentioned multi-crystal TFT that obtains by the low temperature polycrystalline silicon processing according to correlation technique has the characteristic, high carrier mobility and the less deterioration in characteristics that are suitable for relatively large electric current and pass through.Yet, on the other hand, to compare with non-crystalline silicon tft, multi-crystal TFT has between each device and to exist big characteristic to depart from, especially the problem of initial threshold voltage and ON electric current.

In order to prevent this departing from,, attempted making the minimum that departs from each device by the film that use has the similar crystallization of about 300nm that can compare with optical maser wavelength for the crystallization that uses excimer laser.Yet even use the polycrystal film of making by this way, the characteristic that can not suppress fully effectively between each device departs from.

The reason of the problems referred to above is: being undertaken under the situation of crystallization by the crystallization method of use according to the excimer laser annealing device of correlation technique, be difficult to accurately control the size of the crystal grain in the polysilicon membrane, and can obtain uneven particle diameter.The inhomogeneous of particle diameter departed from the crystal boundary number in each thin-film transistor (TFT) groove, cause the departing from of TFT characteristic (for example, with reference to people such as K.Yamaguchi, J.Appl.Phys., Vol.89, No.1, p.590; People such as M.Kimura, Jap.J.Appl.Phys.Vol.40, Part I (2001), No.1 etc.).In addition, because this problem causes the irregular etc. of color on the display part, so especially serious in the display unit of using organic EL device.

In addition, even handle, also be difficult to effectively suppress departing from of above-mentioned TFT characteristic by the low temperature polycrystalline silicon described in the patent documentation 1.This be considered to by the crystal region of forming raceway groove inside extended phenomenon caused, therefore, concentrated reflection departing from such as the influence that has or not of the defective of crystals, dislocation etc. in characteristic.In addition, even under situation, handle by using SLS that departing from of mobility is more than 10% in the multi-crystal TFT that is obtained as the optimization process shown in Figure 8 of non-patent literature 2.This is considered to caused by a plurality of uncontrollable crystal boundary that exists in the crystal region of cross growth part.

Therefore, expectation has the display unit that does not have color or the irregular good display characteristics of brightness.Embodiments of the invention provide a kind of like this display unit: its use transistor characteristic the time become less, carrier mobility is higher and have homogeneous and accurately the thin-film transistor of the transistor characteristic of control as pixel electrode switching element.

More specifically,, provide a kind of display unit, comprised the driving substrate of setting, be arranged with a plurality of pixel electrodes and the thin-film transistor that is used to drive pixel electrode on it according to embodiments of the invention.Each thin-film transistor includes to have by the semiconductive thin film of the active area (active region is also referred to as the active region) of multiple crystallization and the gate electrode that is configured to be crossed with the source region with the energy beam irradiation.In addition, especially with the groove of the active area of gate electrode in, crystalline state is along the length direction periodic variation of raceway groove, and essentially identical crystalline state is across groove.

In the display unit of as above structure, by across the crystal boundary that periodically is provided with, the charge carrier of the groove of the thin-film transistor by being used to drive pixel electrode inerrably moves.Therefore, by the cycle of control crystal boundary, the accurately transistor characteristic of control TFT (carrier mobility).For example, the periodicity that is provided with in cycle size or groove (crystal boundary number) is configured under the consistent situation, can suppress departing from of carrier mobility between a plurality of devices.In addition, can see that the crystalline state in each cycle is controlled to be under the situation of predetermined state in this structure, can keep using the higher carrier mobility of the device advantage of the thin-film transistor of making many crystallizations, and the deterioration of suppression device characteristic.

As mentioned above, according to embodiments of the invention, the time change of transistor characteristic is less, carrier mobility is higher and have homogeneous and the thin-film transistor of the transistor characteristic of accurate control is used as pixel electrode switching element.Therefore, can prevent from display unit, to produce the irregular of color or brightness, and improve the display characteristic of display unit.

Description of drawings

Fig. 1 is the schematic diagram according to the display unit of the embodiment of the invention;

Fig. 2 is the circuit diagram according to the display unit of present embodiment;

Fig. 3 is the plane graph that is arranged on the general structure of thin-film transistor in the display unit that illustrates according to present embodiment;

Fig. 4 A and Fig. 4 B are that the groove to be arranged on the thin-film transistor in the display unit that illustrates according to present embodiment is the plane graph of the active area structure at center;

Fig. 5 is the amplification view of first example of groove (active area) that thin-film transistor in the viewing area is shown;

Fig. 6 is the amplification view of second example of groove (active area) that thin-film transistor in the viewing area is shown;

Fig. 7 A and Fig. 7 B are the amplification views of the another example of groove (active area) that thin-film transistor in the viewing area is shown;

Fig. 8 A～Fig. 8 D shows the cross section block diagram of explanation method for fabricating thin film transistor;

Fig. 9 A and Fig. 9 B are the amplification views of example of the crystallization method of groove (active area) that thin-film transistor in the viewing area is shown;

Figure 10 is the amplification view of another example of the crystallization method of groove (active area) that thin-film transistor in the viewing area is shown;

Figure 11 is the amplification view of another example of the crystallization method of groove (active area) that thin-film transistor in the viewing area is shown;

Figure 12 A～Figure 12 C is the amplification view of an example again of the crystallization method of groove (active area) that thin-film transistor in the viewing area is shown; And

Figure 13 A and Figure 13 B are the manufacturing step figure of display unit.

Embodiment

Now, be discussed in more detail below embodiments of the invention with reference to the accompanying drawings.Incidentally, in the following embodiments, apply the present invention to use the top gate type multi-crystal TFT to be described as an example as the structure of the liquid crystal indicator of pixel switch element.

The general structure of＜display unit 〉

Fig. 1 shows the schematic sectional view as display unit display unit example according to the present invention, that have liquid crystal panel.As shown in the figure, the display unit 1 among this embodiment has LCDs 101.LCDs 101 has and is clipped in first substrate 103 positioned opposite to each other and the liquid crystal layer 105 between second substrate 104.

For this assembly, form first substrate 103 by using such as the printing opacity insulated substrate of synthetic quartz substrate, and be configured to so-called driving substrate, wherein, mid portion is as viewing area 103a, and arranges pixel electrode and as the thin-film transistor of the switch element that is used to drive pixel electrode on the surface of the viewing area 103a relative with liquid crystal layer 105.In addition, form second substrate 104 such as the printing opacity insulated substrate of synthetic quartz substrate by using, its with liquid crystal layer 105 facing surfaces on arrangement to electrode (opposite electrode).In addition, by the sealant 106 that is arranged between first substrate 103 and second substrate, 104 marginal portions liquid crystal layer 105 is sealed between first substrate 103 and second substrate 104.

Fig. 2 shows the circuit diagram of first substrate, 103 sides in the display unit of as above constructing.Multi-strip scanning line 111 and many signal line 112 are arranged among the viewing area 103a of first substrate, 103 central part offices setting with matrix form.Locate to be provided with thin-film transistor (TFT) Tr1, connected auxiliary capacitor element 114 and pixel electrode 115 in scan line 111 and each crosspoint of holding wire 112.In the external zones 103b of 103a periphery, viewing area, peripheral circuit is set, for example, vertical transfer circuit 116 that is connected with scan line 111 and the horizontal transport circuit 117 that is connected with holding wire 112.Incidentally, these peripheral circuits also comprise thin-film transistor Tr2, capacity cell and the wiring diagram that connects them.

In display unit according to this embodiment, the thin-film transistor Tr1 that is provided with among the viewing area 103a on first substrate, 103 sides and being arranged in each of thin-film transistor Tr2 among the external zones 103b, the configuration condition of the crystalline state of active area 5a and the gate electrode 9 relevant with this crystalline state is specific.

Fig. 3 illustrates each the plane graph of general structure of thin-film transistor Tr1 and Tr2.As shown in Figure 3, each of thin-film transistor Tr1 and Tr2 all has active area 5a that comprises semiconductive thin film 5 and the gate electrode 9 that connects up with the state that is crossed with source region 5a mid portion.

For this assembly, the active area 5a that comprises semiconductive thin film 5 is the zone of coming multiple crystallization by the semiconductive thin film 5 that is formed by amorphous silicon with the energy beam irradiation such as laser beam.In addition, semiconductive thin film 5 is patterned to including the island shape of source region 5a.In this case, as shown in the figure, can make amorphous semiconductor films 5 parts do not remain in multiple crystallization active area 5a around come semiconductive thin film 5 is carried out one patterned.Perhaps alternatively, amorphous semiconductor films 5 parts can be remained in active area 5a around.

In above-mentioned active area 5a, with the part of the overlapping active area 5a of gate electrode 9 as groove C.In addition, in active area 5a, the zone of groove C both sides forms source/drain 11.

Fig. 4 A and Fig. 4 B are the structural plan figure that active area 5a-1, the 5a-2 of the groove C centre that is positioned at the distinctive thin-film transistor Tr1 of present embodiment, Tr2 are shown.Fig. 4 A is the plane graph that the active area 5a-1 of thin-film transistor Tr1 is shown, and Fig. 4 B is the plane graph that the active area 5a-2 of thin-film transistor Tr2 is shown.

As shown in the figure, for example, among the active area 5a-1 of the thin-film transistor Tr1 in being arranged on viewing area 103a, along the bearing of trend of gate electrode 9 be arranged with crescent crystal grain b, b ...On the other hand, among the active area 5a-2 of the thin-film transistor Tr2 in being arranged on external zones 103b, banded crystal grain B extends on substantially identical with gate electrode 9 direction.

Now, with their structures separately and the order that is formed with the method in source region the active area 5a-1 of thin-film transistor Tr1, Tr2, the detailed structure of 5a-2 are described.

The structure of thin-film transistor Tr1 in the＜viewing area 〉

Shown in the amplification view of Fig. 4 A, the active area 5a-1 that is arranged on the thin-film transistor Tr1 among the 103a of viewing area comprise crescent crystal grain b, b ... array.

In active area 5a-1, the crystalline state among the groove C is along the direction periodic variation of channel length at least, and essentially identical crystalline state is across groove C.Particularly, in this case, with state, be provided with along the crystal boundary a of a plurality of series of the bearing of trend of gate electrode 9 with gate electrode 9 C of trench overlapped portion at least across groove C, and these crystal boundaries a keeps periodically being provided with in the predetermined period P in the direction along channel length L.

Along the bearing of trend of gate electrode 9, the crystalline state between the crystal boundary a-a is basic identical.Incidentally, the grain boundary structure that periodically is provided with not only can cover groove C as mentioned above, and can cover the whole zone of each active area 5a-1.

As what in the description of manufacture method after a while, will describe in detail, a series of crystal boundary a be for example when keeping predetermined period P by the parallel sweep energy beam generate and the crystal boundary parallel with the scanning direction.

In addition,, and the crystal boundary a of predetermined number thereunder is set here based on the live width (corresponding to channel length L) of the specifications design gate electrode 9 of the thin-film transistor that forms, with on channel width W direction across groove C.Especially, can require to be arranged on the characteristic unanimity of the thin-film transistor Tr1 in the viewing area, make that the crystal boundary a that essentially identical number is set is particularly important in each groove C.The term of Shi Yonging " essentially identical number " is meant the preferably number in the scope of (predetermined number) ± 1 herein.

In addition,, diminish, can make the characteristic of thin-film transistor depart from homogenization along with the ratio of actual number and predetermined number departs from for the number that is arranged on the crystal boundary a among the groove C.Therefore, more preferably, the number that is arranged on the crystal boundary a among the groove C is bigger, 2 or above scope in.Particularly, as described about embodiment after a while, preferably, according to channel length cycle P is set in the mode that in groove C, is arranged on about 25 the crystal boundary a that extend on the channel width dimension.Yet, be noted here that along with the number across the crystal boundary a of raceway groove length L direction among the groove C becomes big, carrier mobility on the channel length L direction reduces, therefore, preferably, keeping the high number that increases crystal boundary a in the scope of specific degrees that arrives of carrier mobility.

In addition, in order to stablize the above-mentioned number that is arranged on the crystal boundary a among the groove C, a plurality of crystal boundary a in the groove C of active area 5a-1 are set parallel to each other at least, and its cycle P is constant.

Fig. 5 is the amplification view that first example of groove C among the thin-film transistor Tr1 (active area 5a-1) is shown.As shown in the figure, in the groove C of crystal boundary a (active area 5a-1) is set as mentioned above, preferably, the crescent crystal grain b of projection on the bearing of trend that is arranged in crystal boundary a between the crystal boundary a.The size of these crystal grain b is to arrange between crystal boundary a-a and along the bearing of trend of crystal boundary a fully.In addition, preferably, in comprising the active area 5a-1 of groove C crystal boundary a is set periodically, wherein, active area 5a-1 crystallization in whole zone does not comprise any non-crystalline areas.

Fig. 6 is the amplification view that second example of groove C among the thin-film transistor Tr1 (active area 5a-1) is shown.As shown in the figure, the thin-film transistor Tr1 in being arranged at the viewing area is used under the situation of pixel switch purpose, and crystal boundary a1 can be configured to non-crystalline areas.In this case, preferably, the zone of a crystal wherein be arranged with along the crescent crystal grain b of the bearing of trend projection of crystal boundary a1 is set respectively between crystal boundary a1, wherein, crystal boundary is constituted as non-crystalline areas (amorphous ribbon) and each all has preset width.The size of crystal grain b is to arrange between crystal boundary a1-a1 and along the bearing of trend of crystal boundary a1 fully.

Incidentally, the crystal boundary a1 structure example that is set to non-crystalline areas is not limited to second example shown in Fig. 6.

For example, shown in Fig. 7 A, be arranged in the crescent crystal grain b of projection on the bearing of trend of the crystal boundary a1 that forms non-crystalline areas in two row that can be between crystal boundary a1 (or more multirow).In this case, between the row of arranging crystal grain b, be provided with, and arranged size for fully between between the crystal boundary a1-a and meniscate crystal grain b with projection on the bearing of trend of crystal boundary a1, a along the continuous wire crystal boundary a of the bearing of trend of crystal boundary a1.In addition, periodic structure is set, wherein, arranges crystal grain b in two row between the crystal boundary a1 that is configured to non-crystalline areas and is provided with or the multirow with predetermined period P.

In addition, the shape that is arranged in the crystal grain b between the crystal boundary a1 that forms non-crystalline areas is not limited to crescent.

For example, shown in Fig. 7 B, can arrange the crystal grain b ' that has by the half moon that the second-class branch of crescent is obtained with linear symmetric.In this case, between the row of crystal grain b ', be arranged alternately crystal boundary a1 and the wire crystal boundary a that forms non-crystalline areas.

Above-mentioned crescent crystal grain b and half moon crystal grain b ' are by the formed crystal grain of bearing of trend scanning energy bundle along crystal boundary a, a1, will describe its formation method below in the description of manufacture method in detail.

The manufacture method of thin-film transistor Tr1-1 in the＜viewing area 〉

At first, based on Fig. 8 A～Fig. 8 D and with reference to other figure, be described below the manufacture method of the thin-film transistor Tr1 of the structure of describing with reference to Fig. 4 A and Fig. 5 before having.

At first, shown in Fig. 8 A, prepare to be used to form the substrate 3a of thin-film semiconductor device.The example of substrate 3a comprises as the glass of amorphous substrate, quartz or sapphire substrate, plastic base and the metal substrate made by aluminium, stainless steel etc.

Buffer insulation layer 3b to substrate 3a is provided for preventing to conduct heat on the interarea of substrate 3a.The example of resilient coating 3b comprises the oxide-film of silicon oxide layer, silicon nitride layer, silicon carbide layer etc. and Ti, Al, Zr, Hf etc.Can form resilient coating 3b by any known vacuum diaphragm formation technology such as CVD, sputter and gas deposition.In addition, for example, also can will be used as any dielectric film of interlayer dielectric (for example, inorganic sog film and organic sog film) usually as resilient coating 3b.In addition, can will be used as resilient coating 3b by the formed any dielectric film of anodic oxidation of metal film and the film that forms by known technology such as collosol and gel processing and MOD (metal organic deposit).

Next, on the interarea of first substrate 103, form amorphous semiconductor films 5 with the surface that as above covers by resilient coating 3b.As an example, handle the semiconductive thin film 5 that formation comprises amorphous silicon herein, by PE-CVD (plasma enhanced chemical vapor deposition).Thus obtained semiconductive thin film 5 comprises so-called amorphous silicon hydride (a-Si:H), and it comprises a large amount of hydrogen.In addition, the thickness of formed here semiconductive thin film 5 is for example 20nm～100nm.

Incidentally, the method that forms semiconductive thin film 5 is not limited to above-mentioned PE-CVD and handles, because it is a kind of method that the film formation temperature can be remained on low temperature; Therefore, can adopt coating processing.In this case, will comprise the mixture that is blended in the polysilane compound in the solvent and be coated on the substrate 103, carry out drying and annealing subsequently, to form semiconductive thin film 5.In any film formation method that the film formation temperature is remained on low temperature (for example, the PE-CVD that has just mentioned handles and coating processing), can obtain to comprise the semiconductive thin film 5 of the amorphous silicon hydride (a-Si:H) of the hydrogen that contains about 0.5～15atoms%.

Subsequently, if desired, then execution is used for removing superfluous hydrionic so-called dehydrogenation processing in semiconductive thin film 5.For example, carrying out dehydrogenation by the smelting furnace of annealing under 400 ℃～600 ℃ temperature handles.Yet, can not cause from the part of laser beam irradiation, to remove superfluous hydrogen under the situation of the hydrionic gasification that is included in the semiconductive thin film 5 or hydrogen expander carrying out subsequently crystallization annealing in process by the control irradiation energy, can omit dehydrogenation and handle.

After above-mentioned steps, shown in Fig. 8 B, carry out crystallization step, wherein,, the active area 5a-1 that is arranged in the semiconductive thin film 5 is carried out crystallization by irradiation as the laser beam Lh of energy beam.

In crystallization step, by laser beam Lh irradiation semiconductive thin film 5, simultaneously in a predetermined direction with set rate scanning laser beam Lh.

In this case, (that is, the direction of channel length L) moves the irradiation position of laser beam with preset space length on the Width that will form gate electrode 9, and sentencing predetermined scanning direction y scanning laser beam Lh according to each irradiation position that moves.Here, the scanning direction y of laser beam Lh is set to basic consistent with the bearing of trend of gate electrode 9, that is, consistent with the direction of channel width W.Therefore, in each active region 5a-1, the irradiation position of mobile laser beam Lh on the direction that is provided with according to gate electrode 9 wiring directions, and sentence predetermined scan direction y scanning laser beam Lh at each irradiation position that moves.

In addition, in crystallization step, the sweep speed of exposure, point of irradiation diameter, laser beam Lh and the moving interval of irradiation position etc. are set in the mode that linear crystal boundary a occurs with predetermined period P of the scanning direction y that is parallel to laser beam Lh.

For crystallization step, for example, can mention the method for the blast crystallization (explosive crystallization) of employing shown in Fig. 9 A.Thereby in order to shine the crystallization that sets off an explosion by this way, illuminate condition by the laser beam Lh of size, irradiation speed and the irradiation energy control of irradiation area is set in the mode that before the semiconductive thin film 5 in institute's irradiated region melts fully when the scanning laser beam Lh heat is reached the semiconductive thin film 5 in the institute irradiation area peripheral region by laser beam Lh.

In this case, the thickness of based semiconductor film 5 and absorption coefficient are chosen as the wavelength of laser beam Lh of irradiation semiconductive thin film 5 and are used for guaranteeing that relatively low absorption coefficient makes laser beam Lh ad infinitum be absorbed semiconductive thin film 5 and can not see through the value that semiconductive thin film 5 transmits.Especially, has in the example of 50nm thickness the preferred laser beam that uses with 350nm～470nm wavelength at the semiconductive thin film 5 that forms by amorphous silicon.The example of oscillation source with laser beam Lh of this wavelength comprises based on GaN's or other compound semiconductor laser oscillator and YAG laser oscillator.Can control other illuminate condition except that laser beam Lh wavelength, for example, be used for, thereby can realize the blast crystallization of semiconductive thin film 5 with the numerical aperture NA of the object lens of laser beam Lh irradiation and sweep speed and the irradiation energy of laser beam Lh.

Subsequently, each the irradiation position place that on the direction of channel length L, moves laser beam Lh with predetermined moving interval p1, under above-mentioned illuminate condition, scanning laser beam Lh on basic vertical scanning direction y with channel length L direction.In this case, the spot diameter r1 of the laser beam Lh that control and mobile pitch P 1 are relevant makes not residual non-crystalline areas between the adjacent irradiation position of laser beam Lh and the generation continuous grain crystal a parallel with scanning direction y.

Above result is, the mode that the cycle P that equates with the width with moving interval p1 is provided with crystal boundary a is carried out the multiple crystallization of semiconductive thin film 5.So, along the crescent crystal grain b of the bearing of trend of crystal boundary a projection on the scanning direction y that is arranged in laser beam Lh between the crystal boundary a-a.

Here, the moving interval p1 of the spot diameter r1 of laser beam Lh and laser beam Lh irradiation position (the cycle P of crystal boundary a) is the key factor of number (periodicity) that is used for determining being arranged on the crystal boundary a of groove.As described in the description of display device structure, with the number (periodicity) that is arranged on the crystal boundary a in the groove be provided with bigger, it is in the scope of guaranteeing carrier mobility and for reducing the degree that departs from (to evenly) of transistor characteristic.Here, the number of the crystal boundary a in making groove further is provided with moving interval p1 (the cycle P of crystal boundary a) under the big as much as possible situation in the scope of the production time of not disturbing processing (tact time).The spot diameter r1 of laser beam Lh is set according to moving interval p1 in this mode that does not have residual non-crystalline areas and generate continuous crystal boundary a in addition.

Therefore, when the channel length (live width of gate electrode) of hypothesis thin-film transistor is not more than 10 μ m usually, consider productivity ratio, preferably in groove C, form about 25 crystal boundary a.In this case, the moving interval p1 (the cycle P of crystal boundary a) with the irradiation position of laser beam Lh is set to about 400nm.It is suitable with moving interval p1 (the cycle P of crystal boundary a) that spot diameter r1 is set to basic, and it is arranged on about hundreds of nanometers in 1nm～10 mu m ranges, thereby between the adjacent irradiation position of laser beam Lh irradiation, generate the continuous grain crystal a that is parallel to scanning direction y.

Except that above-mentioned blast crystallization, can carry out crystallization step near the mode that the point of irradiation center of laser beam Lh, generates the continuous grain crystal a that is parallel to scanning direction y shown in Fig. 9 B.In order to shine by laser beam Lh to generate crystal boundary a in such position, scanning laser beam Lh makes to be melted fully in the gamut of each position semiconductive thin film 5 at depth direction of laser beam Lh irradiation.

In this case, the thickness of based semiconductor film 5 and absorption coefficient are controlled such as the wavelength of laser beam Lh, are used for numerical aperture NA and the sweep speed of laser beam Lh and the illuminate condition of irradiation energy by the object lens of laser beam Lh irradiation, thus on depth direction melting semiconductor film 5 fully.In addition, under the situation of carrying out this crystallization, the situation of the blast crystallization of describing with reference to Fig. 9 A above being similar to, can use by using based on GaN's or the laser beam Lh of 350nm～470nm wavelength that other compound semiconductor laser oscillator or YAG laser oscillator are obtained, and by the above-mentioned illuminate condition of control melting semiconductor film 5 fully on depth direction.

In this case, scanning laser beam Lh goes up at basic vertical with channel length L direction scanning direction y (bearing of trend of above-mentioned grid wiring) in each the irradiation position place that moves laser beam Lh with predetermined moving interval p2 on the direction of channel length L.In this example, control spot diameter r2 (on channel length L direction) with not residual non-crystalline areas between the adjacent position of laser beam Lh irradiation and the mode that generates the continuous grain crystal a parallel with respect to the laser beam Lh of the moving interval p2 of laser beam Lh with scanning direction y.

Above result is, carries out the multiple crystallization of semiconductive thin film 5, makes the cycle P that equates with moving interval p2 with width that crystal boundary a is set.So, be arranged in crescent crystal grain b protruding on the direction opposite between the crystal boundary a-a with the scanning direction y of laser beam Lh along the bearing of trend of crystal boundary a.According to this crystallization step, recrystallize semiconductive thin film 5 acquisition crystal grain b by the complete melting semiconductor film 5 of the irradiation of laser beam Lh and by liquid growth, therefore, crystalline quality is fine, and has improved carrier mobility.

In this case, with with before with reference to the identical mode of situation of the described blast crystallization of Fig. 9 A, the number that the spot diameter r2 of laser beam Lh and the moving interval p2 of laser beam Lh irradiation position (the cycle P of crystal boundary a) is set to crystal boundary a in the groove is big as much as possible in the scope of the production time of not disturbing processing.

Here, with reference in Fig. 9 A and described each crystallization step of Fig. 9 B, the characteristic homogenization of shining formed crystal boundary a by laser beam Lh is very important in the above.As the factor of the characteristic homogeneous that makes crystal boundary a, need laser radiation constant energy density, the sweep speed at each irradiation position place constant, moving interval p1, the p2 constant (cycle, P was constant) at irradiation position place and the thickness homogeneous of semiconductive thin film 5.

In addition, in order to make the irradiation energy density constant of laser beam Lh, expectation realizes the continuous oscillation of laser beam Lh at least during shining active area 5a-1 by laser beam Lh.There is stop (rest) (what for example, 50ns was following stopping) in the scope that the temperature of semiconductive thin film 5 of being included in term used herein " continuous oscillation " does not reduce.In addition, in order to shine with the constant illumination energy density by laser beam, the laser beam irradiation system with feedback function and focus servo functionality is used in expectation.Feedback function and the focus servo functionality that can construct energy by the known technology in the cutting machine (cuttingmachine) that is used in CD etc.

The irradiation of semiconductive thin film 5 is set in the constant scope of the sweep speed of laser radiation in addition.

Moving of laser beam irradiation position with respect to semiconductive thin film can be to relatively move.That is, the substrate that is provided with semiconductive thin film can move with respect to the irradiation position of fixing laser beam, and perhaps alternatively, the irradiation position of laser beam can move with respect to fixing substrate.In addition, can moving substrate 1 and the irradiation position of laser beam.

In addition, by using the parallel sweep of the laser beam Lh in each crystallisation step that single laser oscillator describes with reference to Fig. 9 A and Fig. 9 B before can carrying out in proper order, perhaps can carry out by using a plurality of laser oscillators.In addition, consider the manufacturing of the thin-film transistor that is used to drive display unit, preferably, a plurality of active area 5a-1 are carried out crystallization step simultaneously.Particularly, considering under the situation of productivity ratio that it is preferred shining the method for crystallization step that a plurality of active area 5a-1 can be arranged in a plurality of active area 5a-1 of substrate 3 face side simultaneously simultaneously by laser beam Lh.

In order to realize this multiple spot irradiation by laser beam Lh, semiconductor laser oscillator is used as the laser beam source.With compare such as other laser oscillator of excimer laser and YAC laser, the size of semiconductor laser oscillator is very little, therefore, can dispose a plurality of semiconductor lasers in single assembly, in addition, under the situation of Continuous irradiation, can realize the specified output of 200mW.

By using semiconductor laser oscillator, increase the number of semiconductor laser by increase according to substrate area, can be with device design and substrate size coupling neatly.Therefore, can obtain to arrange on large-size substrate a plurality of transistorized structure with identical performance, this structure is than forming on large tracts of land in the transistor process with homogeneous characteristic as having more advantage by the method for using mask control crystal boundary in the report of conceptual phase.

After the above-mentioned crystallization step of finishing shown in Fig. 8 C, carry out semiconductive thin film 5 is etched into the pattern etching of reservation shape, keeping the active area 5a-1 of crystallization, and active area 5a-1 is divided into the shape on similar island so that device isolation.In this case, as shown in the figure, can carry out the pattern etching of semiconductive thin film 5 in the not crystallization mode partly of not residual semiconductive thin film 5 around active area 5a-1.Perhaps alternatively, can carry out the pattern etching of semiconductive thin film 5 to keep not the mode of semiconductive thin film 5 parts of crystallization around the active area 5a-1.Incidentally, can before above-mentioned crystallisation step, carry out this pattern etching of semiconductive thin film 5.In this case, make the part that is patterned to the semiconductive thin film 5 of the shape on similar island that comprises the zone that becomes active area 5a-1 stand above-mentioned crystallization step.

Next, the state with the active area 5a-1 of overlapping patternization is formed on gate insulating film 7 on the substrate 1.Gate insulating film 7 can be formed by silica or silicon nitride, and can form by the known method of handling such as common PE-CVD; In addition, can gate insulating film 7 be formed the application type dielectric film by known SOG etc.Incidentally, can before the pattern etching of semiconductive thin film 5, form gate insulating film 7.

Subsequently, on gate insulating film 7, form gate electrode 9 across the form of the active area 5a-1 core of the above-mentioned shape that is divided into similar island.Here, as top described, form gate electrode 9 along the bearing of trend that is formed on the crystal boundary a among each active area 5a-1 with reference to Fig. 4.In this case, have at device under the situation of identical characteristics, the gate electrode 9 with identical live width is carried out one patterned, make the crystal boundary a that similar number is set below each gate electrode 9.

In the process of above-mentioned formation gate electrode 9, at first, for example form the electrode material layer of aluminium by sputter or gas deposition.Next, on electrode material layer, form pattern against corrosion by photoetching process.After this, should be used as mask by pattern against corrosion, the etched electrodes material layer is to carry out one patterned to gate electrode 9.

Incidentally, the formation of gate electrode 9 is not limited to said process, for example, can adopt the printing technology of metallizing particle.In addition, in the etching process of the electrode material layer that forms gate electrode 9, but etch-gate dielectric film 7 subsequently.

After this, shown in Fig. 8 D,, in active area 5a-1, form source/drain 11 with introducing impurity wherein based on autoregistration by gate electrode 9 is used as mask.Here, for example, carry out the ion of gate electrode 9 as mask injected.

Above result is, on the downside of gate electrode 9, form crystallization active area 5a-1 have a groove C that the part of not introducing impurity is therein formed.The source/drain 11 of gate electrode 9 belows and groove C be by forming by the polysilicon that crystallization obtained of semiconductive thin film 5, thereby obtain the thin-film transistor Tr1 with reference to Fig. 4 A and the described structure of Fig. 5.

The manufacture method of thin-film transistor Tr1-2 in the＜viewing area 〉

For example, have under the situation of thin-film transistor Tr1 of the active area 5a-1 that describes with reference to Fig. 6 above being configured to, can use method based on the blast crystallization of describing with reference to Fig. 9 A above using in manufacturing.

Yet, here should be noted that, as shown in figure 10, on channel length L direction, move in the process of laser beam Lh with preset space length p1, spot diameter r1 with respect to laser beam Lh in the scope that laser beam Lh does not overlap each other controls moving interval p1, to guarantee that relict structure is the crystal boundary a1 with preset width of non-crystalline areas between the adjacent irradiation position of laser beam Lh.

Such result is to carry out the multiple crystallization of semiconductive thin film 5, the feasible crystal boundary a1 with preset width that is configured to non-crystalline areas with the cycle P setting that equates with moving interval p1.Guaranteed the crescent crystal grain b of projection on the scanning direction y that is arranged in laser beam Lh between the crystal boundary a1-a1 along the bearing of trend of amorphous crystal boundary a1 like this.

In addition, as top described with reference to Fig. 7 A, a plurality of row between amorphous crystal boundary a1-a1 (for example, two row) arrange under the situation of crescent crystal grain b in, on the y of scanning direction, carry out the scanning first time of laser beam Lh, then with the irradiation position of first preset space length mobile laser beam Lh on channel length L direction, overlap each other with afterwards laser beam Lh before making, and carry out the scanning second time of the laser beam Lh on the y of scanning direction at the irradiation position place that moves.In this way, form the crystal grain b in second row, on the y of scanning direction, form continuous grain crystal a at them and between simultaneously by the crystal grain b that the first time, scanning formed, and not residual any non-crystalline areas.In addition, on the both sides of crystal boundary a, arrange crescent crystal grain b.Then, irradiation position with second preset space length mobile laser beam Lh on the direction of channel length L, do not overlap each other with afterwards laser beam Lh before making, and the residual crystal boundary a1 that is constructed to non-crystalline areas, and be in the scanning first time of carrying out laser beam Lh on the y of scanning direction at the irradiation position that moves with preset width.After this, under the fixing situation of first preset space length and second preset space length, repeat the scanning second time of laser beam Lh and scan the first time of laser beam Lh.Incidentally, in all having three or more row between the crystal boundary a1-a1 of preset width, each arranges under the situation of crescent crystal grain b, after moving irradiation position with first preset space length and carrying out the scanning second time of laser beam Lh, further move irradiation position and carry out the scanning for the third time (or more than three times) of laser beam Lh with first preset space length, carry out the scanning first time of laser beam Lh then, and repeat to reach for the second time scanning subsequently.

The manufacture method of thin-film transistor Tr1-3 in the＜viewing area 〉

At first, have under the situation of thin-film transistor Tr1 of the active area 5a-1 that describes with reference to Fig. 7 B above being constructed in manufacturing, for example, can use the method for describing with reference to Fig. 9 B as top of using based on the crystallization that is used for the complete melting semiconductor film 5 of gamut on depth direction.

Here, as shown in figure 11, scanning laser beam Lh goes up at basic vertical with channel length L direction scanning direction y (that is the bearing of trend of above-mentioned grid wiring) in each the irradiation position place that moves laser beam with predetermined moving interval p2 on channel length L direction.In this case, to control the moving interval p2 of the laser beam Lh of the spot diameter r2 (on channel length L direction) with respect to laser beam Lh in the residual mode that is constructed to the crystal boundary a1 with preset width of non-crystalline areas between the adjacent irradiation position of laser beam Lh.

Then, mode with complete melting semiconductor film 5 on depth direction is controlled illuminate condition, thereby carrying out crystallization in the mode of the y-shaped one-tenth continuous grain crystal a of place of the scanning center of laser beam Lh along the scanning direction, and in the both sides of crystal boundary a the bearing of trend along crystal boundary a forms half moon crystal grain b '.In addition, the both sides relict structure in the zone of arranging half moon crystal grain b ' is the crystal boundary a1 with preset width of non-crystalline areas.According to this crystallization step, by the complete melting semiconductor film 5 of the irradiation of laser beam Lh and recrystallize semiconductive thin film 5 by liquid growth and obtain crystal grain b ', make crystalline quality fine, and improved carrier mobility.

The structure of thin-film transistor Tr2 in the＜external zones 〉

Shown in the plane graph that amplifies among Fig. 4 B, the active area 5a-2 that is arranged on the thin-film transistor Tr2 among the external zones 103b comprise banded crystal grain B, B ... array.

In this active area 5a-2, the crystalline state of groove C is along the orientation periodic variation at least, and essentially identical crystalline state is across groove C.Particularly, here, under condition across groove C, at least with gate electrode 9 C of trench overlapped portion in be provided with a plurality of continuous grain crystal a along the bearing of trend of gate electrode 9.These crystal boundaries a periodically is set, on channel length L direction, keeps predetermined period P ' simultaneously.

In addition, between crystal boundary a-a, has banded crystal grain B with spacing P ' same widths along the bearing of trend setting of crystal boundary a.Incidentally, the structure of the banded crystal grain B of periodic arrangement is not necessarily limited to groove C, and it can spread all over the whole zone of active area 5a-2.

Incidentally, with be arranged on the viewing area in the identical mode of thin-film transistor Tr1, design the live width (corresponding to channel length L) of gate electrode 9 here based on the specification of the thin-film transistor that will form, and arrange the crystal boundary a of predetermined number at the downside of gate electrode, with on channel width W direction across groove C.

The manufacture method of thin-film transistor Tr2 in the＜external zones 〉

Outside the crystallization divided by following step alternative semiconductors film 5, with with the top viewing area of describing with reference to Fig. 8 A to Fig. 8 D in the identical mode of manufacture method of thin-film transistor Tr1, can realize the manufacturing of the thin-film transistor Tr2 among the above-mentioned external zones 103b.

At first, shown in Figure 12 A, on fixing scanning direction y, carry out the irradiation of laser beam Lh at a predetermined velocity in the scanning laser beam Lh.Particularly, the illuminate condition of laser beam Lh is set, makes irradiation by laser beam Lh semiconductive thin film 5 fusing fully on its depth direction according to the thickness of semiconductive thin film.In addition, in this crystallization step, preferably will having as above, the laser beam Lh of selected wavelength is used as the some bundle with Gaussian beam section.

By this laser beam Lh of scanning in the path of melting fully at semiconductive thin film, solidify with laser beam Lh pass through carry out simultaneously, and form crystal grain B ' with the state of arranging along the φ of scanning center of laser beam Lh.In this case, by being set to the laser beam Lh of gaussian shape,, the highest and locate minimum at two ends at the scanning center φ place of laser beam Lh by the temperature of the part of laser beam Lh irradiation corresponding to the Gaussian beam section of laser beam Lh.Therefore, by on the y of scanning direction, shining in the scanning laser beam Lh, on the scanning pattern that semiconductive thin film 5 melts fully, crystalline solidification is from range sweep center φ position (from the two side ends in laser beam flying path) farthest, and generates the crystal seed (crystal seed) of given number in the two side ends of scanning pattern.By the further processing of laser beam Lh scanning, solidify towards scanning center and on the y of scanning direction and carry out, and solidify, the feasible crystallization that carries out the φ of scanning center at last in the mode that crystal seed B ' is pulled to the φ of scanning center on the y of scanning direction.In this case, can make that being set in scanning center φ place converges in sweep speed and the output of the scope inner control laser beam Lh of above-mentioned illuminate condition.As a result, obtain half moon (that is the shape that the second-class branch of crescent is obtained by the straight line of guaranteeing the line symmetry) the crystal grain B ' that widens gradually towards the both sides of scanning pattern from the φ of scanning center.

In addition, in this case, the width W 1 of the crystal grain B ' on the scanning direction y of the illuminate condition control laser beam Lh by above-mentioned laser beam Lh.Here, the cycle (preset space length P ') that the width W 1 of control crystal grain B ' becomes crystal boundary a on the y of scanning direction is very important.Therefore, the above-mentioned illuminate condition of laser beam Lh (for example, the wavelength of laser beam Lh, the numerical aperture NA that is used for the object lens by laser beam Lh irradiation and sweep speed and the irradiation energy of laser beam Lh) be in irradiation semiconductive thin film by laser beam Lh on its depth direction fully in the scope of fusing and crystal grain B ' have preset width W1=P '.

Next, shown in Figure 12 B,, move the scanning pattern of laser beam Lh and carry out the scanning second time of laser beam Lh with preset space length P with respect to the scanning pattern that shines before.In this case, the scanning direction y of laser beam Lh is and the parallel fixed-direction in scanning direction that scans for the first time.In addition, the spacing p of the laser beam Lh of parallel sweep (mobile width of scanning pattern) is not more than the diameter r3 (perpendicular to the irradiation diameter on the direction of scanning direction y) of laser beam Lh.The result, carrying out the solidifying of the scanning second time of laser beam Lh with the continuous mode of the crystallinity of the crystal grain B ' at the adjacent scanning position place that is formed on laser beam Lh, and crystal grain B ' (basic direction vertical with scanning direction y) on the direction of the scanning direction that is different from laser beam Lh grows.

In addition, in this case, preferably, the spacing p of the laser beam Lh of parallel sweep is not more than the irradiation radius (r3/2) of laser beam Lh.This makes and is easy to the direction of growth of crystal grain B ' is controlled to be fixed-direction.As mentioned above, when scanning has the laser beam Lh of Gaussian beam profile, on the y of scanning direction and from the both sides of scanning pattern, solidify, thereby form the crystal grain B ' that is the line symmetry about the φ of scanning center towards scanning center's φ side.Therefore, be set to be not more than the irradiation radius (r3/2) of laser beam Lh, carry out crystallization, remain in that scanning direction y goes up and from the part of a distolateral crystal grain B ' who solidifies to scanning center's φ side of scanning pattern by the spacing p of laser beam Lh.Therefore, be easy to the direction of growth of crystal grain B ' is controlled to be fixed-direction.For example, keep when growth has the crystal grain B ' of width W 1 of hundreds of nanometer under the situation of width W 1, scanning has the point-like laser bundle Lh of 200nm to 500nm irradiation radius r, simultaneously to be not more than the spacing p motion scan path of irradiation radius (r3/2).

After this, shown in Figure 12 C, that carries out laser beam Lh respectively in proper order at each place, shift position reaches subsequently scanning for the third time, simultaneously with preset space length p motion scan path.Thus, further carry out the growth of the crystal grain B ' on the direction of the scanning direction y that is different from laser beam Lh, on basic vertical direction, to form the banded crystal grain B that extends with band shape with the scanning direction.In this case, scanning under the identical illuminate condition, carry out the scanning of laser beam Lh in each position, thereby the width W 1 of the banded crystal grain B on the scanning direction remains unchanged with the first time.In addition, by the banded crystal grain B that on the y of scanning direction, arranges, form with width W 1 periodically be provided with crystal boundary a crystal region.In other words, with the preset space length P ' that equates with the width W 1 of banded crystal grain B crystal boundary a is set periodically.

Here, the width W 1 of banded crystal grain B (that is the spacing P ' of crystal boundary a) plays important effect to the number of the crystal boundary a in the groove of determining to be arranged on thin-film semiconductor device in mode same as the previously described embodiments.

Except that above-mentioned crystallization, also exist to be shown in the crystallisation procedure does that forms continuous band-shaped crystal grain B between the crystal boundary a as Fig. 4 B.In this method, for example, on linear short-axis direction, so that moving linear laser beam, spacing P carries out pulse irradiation.Even by this method,, can form crystal boundary a at part place with the overlapping irradiation of laser beam by the linear laser bundle of overlapping each other and being provided with.In this case, by the linear short-axis direction that on channel length L direction, is provided with, crystal boundary periodically is set along channel length L direction.In addition, as claimed in claim, this method is by with preset space length (in the scope that overlaps each other with afterwards energy beam before) irradiation position of mobile energy beam on predetermined moving direction, extends the method example of carrying out multiple crystallization in the crystal boundary on the direction that is different from the energy beam moving direction.

The manufacture method of＜display unit 〉

The following manufacture process of carrying out as the described liquid crystal indicator that sees figures.1.and.2 of the display unit that is provided with above-mentioned thin-film transistor Tr1 and Tr2.

At first, shown in Fig. 8 A, on first substrate 103, form semiconductive thin film 5, and above-mentioned crystallization is applied to semiconductive thin film 5 on viewing area 103a and the external zones 103b.In this case, preferably use the crystallization of semiconductor laser oscillator, thereby will be applied to this zone by the crystallization of different laser beam irradiations.

After this, viewing area 103a on first substrate 103 and external zones 103b are subjected to step of describing with reference to Fig. 8 C and the later step of describing with reference to Fig. 8 D simultaneously, thereby form thin-film transistor Tr1, Tr2 on first substrate 103.

Then, as shown in FIG. 13A, with the state cambium layer dielectric film 21 of cover film transistor Tr 1 (Tr2).The through hole 21a of the source/drain 11 that arrives thin-film transistor Tr1 (Tr2) next, is set for layer dielectric film 21.Then, on layer dielectric film 21, form the wiring 23 that is connected to source/drain 11 by through hole 21a.Incidentally, form other necessary circuitry element by above-mentioned identical step such as capacitor element and wiring diagram.

Next, form planarization insulating film 25 with the state that covers wiring 23, and in planarization insulating film 25, form the through hole 25a that arrives wiring 23.Subsequently, on planarization insulating film 25, form the pixel electrode 115 that is connected to the source/drain 11 of the thin-film transistor Tr1 among the 103a of viewing area by through hole 25a and wiring 23.According to the display type of liquid crystal indicator, pixel electrode 115 is formed transparency electrode or reflecting electrode.Incidentally, Figure 13 A is the sectional view of a pixel major part in the viewing area.

After this, although do not illustrate among the figure here, on planarization insulating film 25, form the alignment film that covers pixel electrode 115, to finish first substrate 103 as driving substrate.

On the other hand, shown in Figure 13 B, prepare second substrate 104 that is oppositely arranged with first substrate (driving substrate) 103.On second substrate 104, common electrode 31 is set, and common electrode 31 is covered by institute's abridged alignment film among the figure.Incidentally, common electrode 31 is formed by transparency electrode.

Then, under the condition that pixel electrode 115 and common electrode 31 face with each other, first substrate (driving substrate) 103 is positioned opposite to each other with second substrate (relative substrate) 104, has spacer 33 therebetween.Then, keep the substrate 103 of predetermined space and the space between the substrate 104 to be full of liquid crystalline phase 105, seal afterwards, thereby finish display unit 1 by spacer 33.

According to the display unit 1 of above-mentioned present embodiment, shown in Fig. 4 A, being used in being arranged at viewing area 103a drives the thin-film transistor Tr1 of pixel electrode, the crystal boundary a that extends along gate electrode 9 across groove C and on channel length L direction periodic arrangement.This structure has guaranteed to pass the inevitable crystal boundary a across periodic arrangement of charge carrier of groove C.Therefore, by the cycle P of control crystal grain, can be with the transistor characteristic (carrier mobility) of the thin-film transistor TFT in the good precision control thin-film semiconductor device 1.Particularly, the size by making cycle P is consistent with the number of crystal boundary a in being arranged on groove C, can suppress departing from of carrier mobility in a plurality of devices.

In addition, arranging along crystal boundary a in the structure that size is being complete crystal grain b between crystal boundary a-a, groove C does not comprise any non-crystalline areas, thus deterioration that can the suppression device characteristic.In addition, between crystal boundary a-a, charge carrier can not pass the crystal boundary between the crystal grain b-b, and it is higher to make that carrier mobility on the channel length L direction keeps.

Owing to can control the cycle P of crystal boundary a by the illuminate condition of aforesaid laser beam Lh well, so can form thin-film transistor TFT with the High Accuracy Control transistor characteristic.

Therefore, constitute display unit 1, can improve the performance of display unit 1, and it is irregular to prevent to produce color in display part by the switch element that this thin-film transistor TFT is used as pixel.

In addition, particularly, the thin-film transistor Tr2 that is used for peripheral circuit in being arranged on external zones 103b, the crystalline state between the crystal boundary a-a is made up of banded crystal grain B identical shown in Fig. 4 B.Therefore, the carrier mobility that is higher than the thin-film transistor Tr1 that is arranged among the 103a of viewing area that the carrier mobility on the channel length L direction among the thin-film transistor Tr2 can be kept.

Therefore, constitute the peripheral circuit of display unit 1, can realize more high performance demonstration by using this thin-film transistor Tr2.

Incidentally, in the above-described embodiments, the structure that applies the present invention to liquid crystal indicator is described.Yet, can be widely used in active matrix type display according to display unit of the present invention, wherein, thin-film transistor is set to be used for the switch element of pixel electrode, and guarantees effect identical or of equal value.For example, applying the present invention under the situation of active matrix organic EL display device, revised the driving circuit structure that uses the pixel electrode of thin-film transistor Tr1, can adopt gratifying structure, wherein, on pixel electrode, form and have, and on organic layer, common electrode formed negative electrode (or anode) such as hole injection layer, luminescent layer, and the organic layer of the necessary function of electron transfer layer.In this organic EL display, show that irregular problem is especially serious, therefore, application of the present invention is to be used to improve the very effective means of image quality.

[example]

＜example 1 〉

The crystallization that is used for the thin-film transistor of viewing area.

At first, handle by PE-CVD that to form by thickness be the semiconductive thin film that the amorphous silicon of 50nm is formed on insulated substrate.

Next, make the active area of semiconductive thin film stand to be undertaken the crystallisation step of multiple crystallization by the irradiation of laser beam Lh.Here, with reference to Fig. 9 A, carry out the crystallization step that is used for semiconductive thin film under the following conditions.

Spot diameter=500nm on the channel length L direction

Spot diameter=300nm on the y of scanning direction

Effective NA=0.6 of object lens

Moving interval p1=400nm on the channel length L direction

Sweep speed vt=3m/ second on the y of scanning direction

Irradiation energy ≈ 15mW on the substrate

Incidentally, carry out the irradiation of the semiconductive thin film that passes through laser beam Lh, make that focal length can not be offset when high-velocity scanning by applying focus servo unchangeably.In addition, monitoring irradiation beam part makes irradiation energy constant, thereby has avoided energy changing.

Observe by laser beam Lh irradiation the zone of crystallization thus down in scanning electron microscopy (SEM).Can determine, between the continuous grain crystal a-a that is provided with cycle P=400nm, obtain the multiple crystallization zone, wherein, the regularly arranged homogeneous crescent crystal grain b that projection on the y of scanning direction is arranged.

＜example 2 〉

The crystallization that is used for the thin-film transistor Tr1 of viewing area.

At first, handle by PE-CVD that to form by thickness be the semiconductive thin film that the amorphous silicon of 50nm is formed on insulated substrate.Next, for from the inner hydrogen of removing surplus of semiconductive thin film, continue 1 hour execution annealing in process (dehydrogenation processing) with 500 ℃ in a vacuum.

Subsequently, the active area of semiconductive thin film stands to be undertaken by the irradiation of laser beam Lh the crystallization step of multiple crystallization.Here, with reference to Fig. 9 B, carry out the crystallization step that is used for semiconductive thin film under the following conditions.

The about 500nm of spot diameter r2=on the channel length L direction, circle

Effective NA=0.8 of object lens

Moving interval p2=400nm on the channel length L direction

Scan velocity V t=1m/ second on the y of scanning direction

Irradiation energy ≈ 12mW on the substrate

Incidentally, carry out the irradiation of the semiconductive thin film that passes through laser beam Lh, make that focal length can not be offset when high-velocity scanning by applying focus servo unchangeably.In addition, monitoring irradiation beam part makes irradiation energy constant, thereby has avoided energy changing.

Observe by laser beam Lh irradiation the zone of crystallization thus down in scanning electron microscopy (SEM).Can determine, between the continuous grain crystal a-a that is provided with cycle P=400nm, obtain the multiple crystallization zone, wherein, the regularly arranged homogeneous crescent crystal grain b that projection on the direction opposite with scanning direction y is arranged.

＜example 3 〉

The crystallization that is used for the thin-film transistor Tr1 of viewing area.

At first, with example 2 in identical process to form what stood that dehydrogenation handles be the semiconductive thin film that the amorphous silicon of 50nm is formed by thickness.

Next, the active area of semiconductive thin film stands to be undertaken by the irradiation of laser beam Lh the crystallization step of multiple crystallization.Here, identical with example 2 with reference to Fig. 9 B, carry out the crystallization step that is used for semiconductive thin film under the following conditions.

The about 500nm of spot diameter r2=on the channel length L direction, circle

Effective NA=0.4 of object lens

Moving interval p2=600nm on the channel length L direction

Sweep speed vt=3m/ second on the y of scanning direction

Irradiation energy ≈ 12mW on the substrate

Incidentally, carry out the irradiation of the semiconductive thin film that passes through laser beam Lh, make that focal length can not be offset when high-velocity scanning by applying focus servo unchangeably.In addition, monitoring irradiation beam part makes irradiation energy constant, thereby has avoided energy changing.

Observe by laser beam Lh irradiation the zone of crystallization thus down in scanning electron microscopy (SEM).Can determine, between the continuous grain crystal a-a that is provided with cycle P=600nm, obtain the multiple crystallization zone, wherein, the regularly arranged homogeneous crescent crystal grain b that projection on the direction opposite with scanning direction y is arranged.

＜example 4 〉

The crystallization that is used for the thin-film transistor Tr2 of external zones.

At first, with example 2 in identical process to form what stood that dehydrogenation handles be the semiconductive thin film that the amorphous silicon of 50nm is formed by thickness.

Next, the active area of semiconductive thin film stands to be undertaken by the irradiation of laser beam Lh the crystallization step of multiple crystallization.Here, with reference to Figure 12 A to Figure 12 C, carry out the crystallization step that is used for semiconductive thin film under the following conditions.

The about 500nm of spot diameter r3=on the channel length L direction, circle

Effective NA=0.8 of object lens

Moving interval p=100nm on the direction vertical with channel length L direction

Sweep speed vt=1m/ second on the scanning direction y (channel length L direction)

Irradiation energy ≈ 12mW on the substrate

Incidentally, carry out the irradiation of the semiconductive thin film that passes through laser beam Lh, make that focal length can not be offset when high-velocity scanning by applying focus servo unchangeably.In addition, monitoring irradiation beam part makes irradiation energy constant, thereby has avoided energy changing.

Observe by laser beam Lh irradiation the zone of crystallization thus down in scanning electron microscopy (SEM).Can determine, obtain the multiple crystallization zone, wherein, regularly arranged have at the basic side upwardly extending banded crystal grain B vertical with scanning direction y.The width W 1 of these banded crystal grain B (that is the cycle P ' of crystal boundary a) is about 400nm.

＜example 5 〉

The crystallization that is used for the thin-film transistor Tr2 of external zones.

Except that the illuminate condition of following change laser beam Lh, repeat the process identical as example 4.

The about 500nm of spot diameter r3=on the channel length L direction, circle

Effective NA=0.4 of object lens

Moving interval p=200nm on the direction vertical with channel length L direction

Sweep speed vt=3m/ second on the scanning direction y (channel length L direction)

Irradiation energy ≈ 12mW on the substrate

Observe by laser beam Lh irradiation the zone of crystallization thus down in scanning electron microscopy (SEM).Can determine, obtain the multiple crystallization zone, wherein, regularly arranged have at the basic side upwardly extending banded crystal grain B vertical with scanning direction y.The width W 1 of these banded crystal grain B (that is the cycle P ' of crystal boundary a) is about 200nm.

＜example 2-1 is to example 5-2 〉

In example 2-1,2-2,3-1 and 3-2, make the thin-film transistor Tr1 that is used for the viewing area shown in Fig. 4 A by using the zone of carrying out multiple crystallization as example 2 and example 3.On the other hand, in example 4-1,4-2,5-1 and 5-2, make the thin-film transistor Tr2 that is used for the external zones shown in Fig. 4 B by using the zone of carrying out multiple crystallization as example 4 and example 5.

Shown in following table 1, to each of example 5-2, make thin-film transistor Tr1 or Tr2 with 10 μ m or 20 μ m channel length (grid live width) L and 50 μ m channel width W at example 2-1.In addition, described as reference Fig. 4 A and Fig. 4 B, the gate wirings 5 parallel with crystal boundary a all is set in thin-film transistor Tr1 and Tr2.Incidentally, provided the number of crystal boundary a in the groove of example 2-1 thin-film transistor to the example 5-2 in the table 1.

[table 1]

		Numerical aperture NA	Channel length L	The number of crystal boundary a (cycle)	Departing from ± σ of ON electric current	Vth departs from	Mobility (cm 2/Vs)
								Tr1 Fig. 4 A	Example 2-1	0.8	10μm	25	±1.9％	0.08V	26
Example 2-2	20μm	50	±1.3％	0.06V	26
						Example 3-1	0.4		10μm		17	±0.94％	0.10V	18
Example 3-2	20μm	33	±0.56％	0.06V	18
						Tr2 Fig. 4 B			Example 4-1	0.8	10μm	25	-	0.29V	120
Example 4-2	20μm	50	-	0.18V	155
							Example 5-1	0.4	10μm		50	-	0.10V	200
Example 5-2	20μm	100	-	0.09V	210

Channel width W=50 μ m (when the processing improvement of NA=0.4)

For each thin-film transistor of as above making, measured departing from and carrier mobility of threshold value Vth.In addition, for the thin-film transistor Tr1 of the viewing area in example 2 and the example 3, measure departing from of ON electric current.In table 1, provide these measurement results together.Incidentally, by test each example of processing execution and comparison example.Therefore, compare with other example, effective NA of object lens is that 0.4 example 3 and example 5 comprise and handle the result's (navigability particularly) who improves.

Can determine from these results, in the thin-film transistor Tr1 of viewing area (example 2-1 is to example 3-2), in the thin-film transistor that obtains, number change big (along with periodicity becomes big) along with crystal boundary a, the σ that departs from of the departing from of ON electric current ± σ and threshold value Vth diminishes, and the precision of characteristic is better.Particularly, be 0.8 and do not improve under the situation about handling (example 2) at effective NA of object lens even can determine, if the number of crystal boundary a is about 25, also departing from of ON electric current can be suppressed in 3%, even and, also can effectively brightness be departed from being suppressed at the unrecognizable grade of vision in that this thin-film transistor is used as under the situation of the switch element of pixel electrode in the display unit of using organic EL device.Even can also determine under effective NA of object lens is low to moderate 0.4 situation, also can the departing from of ON electric current ± σ be suppressed at enough low grade to be 0.8 identical mode with effective NA.

In addition, can determine that in the thin-film transistor Tr2 of external zones (example 4-1 is to example 5-2), in the thin-film transistor that obtains, along with the number change of crystal boundary a is big, departing from of Vth diminishes in the transistor, and the precision of characteristic is better.Particularly, be 0.8 and do not improve under the situation of processing (example 4) at effective NA even can determine, if the number of crystal boundary a is 50 or more, also departing from of threshold value Vth can be suppressed in the 0.2V, and this thin-film transistor is very suitable for as the switch element that is arranged in the peripheral circuit region with high mobility.In addition, even can determine under effective NA of object lens is low to moderate 0.4 situation, also can the σ that departs from of threshold value Vth be suppressed at enough low grade to be 0.8 identical mode with effective NA.

It should be appreciated by those skilled in the art, multiple modification, combination, recombinant and improvement to be arranged, all should be included within the scope of claim of the present invention or equivalent according to designing requirement and other factors.

Claims (6)

1. a display unit comprises the driving substrate that setting is arranged with a plurality of pixel electrodes and is used to drive the thin-film transistor of described pixel electrode on it,

Wherein, each described thin-film transistor includes:

Have the semiconductive thin film of the active area of multiple crystallization, and be set up gate electrode across described active area by the energy beam irradiation; And with the groove of the described active area of described gate electrode in, crystalline state is along the orientation periodic variation, and essentially identical crystalline state is across described groove.

2. display unit according to claim 1,

Wherein, based on the period of change of described crystalline state, the described groove of described thin-film transistor is provided with crystal boundary across the mode of described active area; And between described crystal boundary, the crescent crystal grain of projection is arranged along the described bearing of trend of described crystal boundary on the bearing of trend of described crystal boundary.

3. display unit according to claim 1,

Wherein, based on the period of change of described crystalline state, amorphous area and crystal region have been arranged alternately across described active area; And

In described crystal region, the crescent crystal grain of projection is arranged along the described bearing of trend of described crystal region on the bearing of trend of described crystal region, and described grain size is in the complete scope on the Width of described crystal region.

4. display unit according to claim 1,

Wherein, described groove is provided with the period of change that is not less than 2 described crystalline state of predetermined number.

5. display unit according to claim 1,

Wherein, the peripheral circuit that utilizes thin-film transistor to constitute is set in the periphery of the viewing area that described pixel electrode and described drive thin film transistors are arranged;

The described transistor that constitutes described peripheral circuit comprises:

Have the semiconductive thin film of the active area of multiple crystallization, and be set up gate electrode across described active area by the energy beam irradiation; And

In mode, the groove with the described active area of described gate electrode is provided with the banded crystal grain that extends along described gate electrode, and described banded crystal grain is provided with periodically along the length direction of described raceway groove across described groove.

6. display unit according to claim 5,

Wherein, the described groove that constitutes each described thin-film transistor of described peripheral circuit is provided with the crystal boundary of the described banded crystal grain that is not less than 2 predetermined period number.

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