CN100521119C

CN100521119C - Semiconductor device and method for manufacturing the same

Info

Publication number: CN100521119C
Application number: CNB2006100997345A
Authority: CN
Inventors: 张宏勇; 鱼地秀贵; 高山彻; 福永健司; 竹村保彦
Original assignee: Semiconductor Energy Laboratory Co Ltd
Current assignee: Semiconductor Energy Laboratory Co Ltd
Priority date: 1992-12-04
Filing date: 1993-12-04
Publication date: 2009-07-29
Anticipated expiration: 2013-12-04
Also published as: CN1877800A

Abstract

A method for manufacturing a semiconductor device such as a thin film transistor. The crystal silicon film is obtained by selectively forming films, particles or clusters containing nickel, iron, cobalt, ruthenium, rhodium, paradium, osmium, iridium, platinum, scandium, titanium, vanadium, chrome, manganese, copper, zinc, gold, silver or silicide thereof in a form of island, line, stripe, dot or film on or under an amorphous silicon film and using them as a starting point, by advancing its crystallization by annealing at a temperature lower than a normal crystallization temperature of an amorphous silicon. A transistor whose leak current is low and a transistor in which a mobility is high are obtained in the same time in structuring a dynamic circuit having a thin film transistor by selectively forming a cover film on a semiconductor layer which is to become an active layer of the transistor and by thermally crystallizing it thereafter.

Description

Semiconductor device and manufacture method thereof

The application is to be that December 4, application number in 1993 are 200410069654.6 and denomination of invention dividing an application for the application of " semiconductor device and manufacture method thereof " applying date.

Technical field

The present invention relates to a kind of method of making integrated circuit, perhaps relate more specifically to comprise array device (comprising electricity-optical display unit and semiconductor memory) and as the MOS of switch element or the semiconductor circuit of MIS (metal-insulator semiconductor) type field effect element (hereinafter generally being referred to as MOS type element) with matrix structure, it is characterized in that its dynamic duty, such as the integrated drive electronics of liquid crystal display and dynamic ram (DRAM) and drive circuit or similar imageing sensor.The present invention be more particularly directed to a kind of employing thin-film semiconductor component, such as the thin film semiconductor's transistor or the analog that are formed at insulating surface, as the device of MOS type element, also relate to have thin-film transistor, its active layer is the device that forms with crystalline silicon.

Background technology

Usually, be used for thin-film device, as film-insulated grid type field-effect transistor (TFT) crystal silicon semiconductor film be the amorphous silicon film that forms with plasma CVD or hot CVD method at a kind of equipment, in electric furnace, be higher than 600 ℃ of methods preparations through carrying out crystallization more than 24 hours in temperature.In order to obtain good feature,, need carry out a lot of hours heat treatment as high-field mobility and high reliability.

Yet there are many problems in usual way.One of problem is that its productivity ratio is low, and it is high that the thing followed is that the cost of product becomes.For example, if when spending 24 hours and doing the crystal processing, and, in the identical time, must handle 720 substrates if 2 fens clock times of every substrate cost are handled.Yet the once multipotency of tube furnace commonly used is handled 50 substrates, when only using an equipment (reaction tube), and every film clips 30 minutes.That is,, just necessary with 15 reaction tubes for handling 1 at 2 minutes.This means to increase scale of investment, and that is because invest by depreciation significantly, but can not reflect in the workinprocess cost.

Another problem is heat treated temperature.Generally, the substrate that is used to make TFT roughly divides for the glass of being made up of pure silica, as quartz glass, non-alkali pyrex, such as Coning No.7059 (hereinafter being referred to as Coning7059).In these substrates, the former is unquestionable with regard to temperature, because its good heat resistance, thereby can operate by the mode identical with the slice, thin piece processing technology of normal semiconductor integrated circuit, yet, its cost height, and index increase with the increase of Substrate Area.So it only is used as the smaller TFT integrated circuit of area.

On the other hand, compare,, aspect heat-resisting, also have problems though the cost of non-alkali glass is very low with quartz glass.Because its strain point generally at 550～650 ℃, to some material that is easy to use, or is lower than 600 ℃.When doing heat treatment, will cause substrate the problem of irreversible contraction or warpage and so on to occur with 600 ℃.Particularly it is remarkable when the diagonal distance of substrate surpasses 10cm.For these reasons, it is believed that to keep heat-treat condition to be lower than 550 ℃ that the time is no more than 4 hours, so that reduce the cost of Si semiconductor membrane crystallizationization.Thereby, an object of the present invention is to provide a kind of method for making semiconductor, it gets rid of these conditions, and adopts this semiconductor to make the method for semiconductor device.

Recently, carried out relevant research with insulated-gate semiconductor device of film active layer (or being called active area).Particularly thin-film insulated gate transistor or so-called thin-film transistor (TFT) have been done ardent research.They are formed on the transparent dielectric substrate, be used for controlling each image and drive it at display device, as the matrix in the LCD with matrix structure, or as a drive circuit that is formed at the image sensor on the dielectric substrate equally.According to the crystal state of used semi-conductive material, they are divided into non-crystalline silicon tft or silicon metal (or claiming polysilicon) TFT.

Recently, just carrying out the research of the material of the intermediate state of utilization between polycrystalline and amorphous silicon.Though intermediate state still is in the discussion, all that is called as silicon metal in this manual with some crystal state that any heat treatment (as using strong energy, resembling laser irradiation, in the annealing of the temperature more than 450 ℃) obtains.

Silicon metal TFT far is used in the monocrystalline silicon integrated circuit as a so-called SOI technology, and it is used as a load transistor in the integrated SRAM of height.Yet, in this case, seldom use non-crystalline silicon tft.

The operating rate of the semiconductor circuit on the dielectric substrate can be very high in addition, because do not have capacitive coupling between substrate and wiring, thereby proposes a kind of technology, makes very high-speed microprocessor or very high-speed memory with it.

Generally, one is in amorphous semi-conductive mobility is low, thereby can not be used for the exigent TFT of operating rate.Also have,, can not make P-type TFT (TFT of PMOS) because the field mobility of P type amorphous silicon is significantly little, thereby, can not combine with N ditch type TFT (TFT of NMOS) and form a complementary MOS circuit (CMOS).

Yet the TFT that forms with amorphous semiconductor has an advantage, and OFF (shutoff) electric current is little.Thereby it can be used to: operating rate require be not very high, only a kind of conduction type gets final product and requires a TFT that the electric charge hold facility is high, as has the transistor of active matrix circuit of the liquid crystal display of minor matrix scale.Yet, non-crystalline silicon tft is used for most advanced and sophisticated the application, as has in the LCD of extensive matrix, be difficult.Also has its peripheral circuit that can not be used to show naturally and drive circuit that requires the high image sensor of operating rate.

On the other hand, the field mobility of crystal semiconductor can high speed operation greater than the mobility of non-crystalline semiconductor.For example, in the TFT that the silicon fiml that is utilized crystallization again by laser annealing makes, obtaining a ground mobility has 300cm ²/ Vs is big.Field mobility by the MOS transistor that forms on normal monocrystalline substrate approximately is 500cm ²/ Vs, top mobility then is a great numerical value.But the operating rate of the MOS circuit on the monocrystalline silicon is limit by the parasitic capacitance between substrate and wiring, concerning the TFT that makes with the silicon fiml of crystallization, does not then have this restriction, because it is formed on the dielectric substrate.So in this TFT, can reach significantly high operating rate of expection.

In addition,, and can also obtain PMOSTFT equally, so can form cmos circuit with silicon metal because can not only obtain NMOS TFT.For example, in the LCD of active matrix system, knownly can constitute one with CMOS silicon metal TFT and not only have the active matrix part, and also have the system of the so-called single chip architecture of peripheral circuit (as driver).Be used for the suggested just this point of TFT of aforesaid SRAM, PMOS wherein is made of TFT as load transistor.

Have again, be used for the self-registered technology of monocrystalline IC technology, in normal amorphous TFT, be difficult for formation source/drain region, and bring a problem by the overlapping parasitic capacitance that causes of the geometry in grid and source/drain region.But silicon metal TFT has the advantage of significantly forcing down this parasitic capacitance, because it can adopt self-registered technology.

Yet when not having voltage to put on grid (non-select period), the leakage current of silicon metal TFT is compared with the leakage current of non-crystalline silicon tft, is big.But take a kind of like this countermeasure, provide an auxiliary capacitor to remove to compensate leakage current, and two TFT are connected in series, reduce its leakage current when being used for liquid crystal display.

For example, propose: form earlier an amorphous silicon, irradiation laser selectively thereon more only makes the method for peripheral circuit crystallization, so that form the peripheral circuit of the monolithic multi-crystal TFT with high mobility on same substrate, the height that utilizes non-crystalline silicon tft simultaneously is by (OFF) impedance.

Yet, its output still is low at present, that is because the reliability of laser irradiation technology still has problem (as bad in the uniformity of irradiating surface internal irradiation energy), thereby adopt finally and a kind ofly constitute a matrix with non-crystalline silicon tft, press the method that TAB or similar approach connect monocrystalline integrated circuit formation drive circuit again.Yet, consider that from the structural limitations that connects this method will be wider than the pixel pitch of 0.1mm, and its cost also becomes very high.

Summary of the invention

The present invention wants to solve these difficult problems, but does not wish to make process complications, and the rate that reduces cost at last raises the cost.The present invention wants to make easily, discriminatingly two types TFT, and the promptly a kind of high TFF of mobility and a kind of low TFT of leakage current that requires of requiring keeps simultaneously producing in batches, and reduce the change of technology as far as possible.

In addition, another object of the present invention is to reduce the difference of NMOS and PMOS mobility in the cmos circuit.The degree of freedom that reduces to increase circuit design of difference between NMOS and PMOS.

It is not omnipotent adopting semiconductor circuit of the present invention.That is, the present invention is suitable for utilizing electric field action to change the sort of material of light transmittance or reflecting rate, material clip between aspectant two electrodes, and is applied the active matrix circuit that electric field comes displayed image between electrode, as LCD; Be used to keep the memory device remembered at capacitor memory storage electric charge, as DRAM: have the circuit of dynamic circuit, as dynamic shift register, it drives next circuit with electric capacity or other electric capacity of the MOS structure position of MOS transistor; And the circuit with digital circuit and the output of control analog signal, as the drive circuit of image sensor.The present invention is particularly suitable for dynamic circuit and static circuit mixes a kind of circuit that is provided with.

The invention is characterized in: earlier on silicon fiml or under form the island film that contains a kind of material of selecting in the group of forming by following material, round dot, particle, agglomerate or lines, make its crystallized temperature in being lower than only general amorphous silicon heat treatment process do the annealing of short period again, can obtain crystal silicon film, these materials are as follows: nickel, iron, cobalt, ruthenium, rhodium, palladium, osmium, iridium, platinum, scandium, titanium, vanadium, chromium, manganese, copper, zinc, golden and silver-colored, and their composition, and silicon fiml (for example is in amorphous state or unordered crystalline state, the state that a kind of part of advantages of good crystallization is mixed mutually with amorphous fraction), we can say it is to be in amorphous state basically.Annealing can be carried out under hydrogen, oxygen or blanket of nitrogen.Annealing can be undertaken by following condition: heated A hour in oxygen containing atmosphere (1), heated B hour in hydrogeneous atmosphere then; (2) in oxygen containing atmosphere, heated C hour, in nitrogen-containing atmosphere, heated D hour again; (3) in hydrogeneous atmosphere, heated E hour, in oxygen containing atmosphere, heated F hour again; (4) in hydrogeneous atmosphere, heated G hour, in nitrogen-containing atmosphere, heated H hour again; (5) in nitrogen-containing atmosphere, heated I hour, in oxygen containing atmosphere, heated J hour again; (6) Heating K hour in nitrogen-containing atmosphere, heating L hour in hydrogeneous atmosphere again; (7) heated M hour in oxygen containing atmosphere, heating is N hour in hydrogeneous atmosphere, heats P hour in nitrogen-containing atmosphere then; (8) in oxygen containing atmosphere the heating Q hour, in nitrogen-containing atmosphere the heating R hour, again in hydrogeneous atmosphere the heating S hour; (9) heated T hour in hydrogeneous atmosphere, heating is U hour in oxygen atmosphere, heats V hour in nitrogen-containing atmosphere again; (10) heated W hour in hydrogeneous atmosphere, heating is X hour in nitrogen-containing atmosphere, heats Y hour in oxygen containing atmosphere again; (11) in nitrogen-containing atmosphere, heated Z hour, in oxygen containing atmosphere, heated A ' hour, in hydrogeneous atmosphere, heated B ' hour again; Or (12) heated in nitrogen-containing atmosphere C ' hour, heated in hydrogeneous atmosphere D ' hour, heated in oxygen containing atmosphere E ' hour again.

About the crystallization of silicon fiml, the past has proposed a kind of island film that forms earlier as the crystallization of nucleus or seed crystal, makes the method for its solid-phase epitaxial growth (for example Japanese kokai publication hei 1-214110) again.Yet, under 600 ℃ temperature, use the method, reluctantly grown crystal.Generally, when silicon when amorphous state changes crystalline state into, it stands a technical process, the amorphous state strand is separated, and after the molecule that separates being placed not the state that is coupled with other molecule, molecule combines with the molecule of some crystallization, and is combined into the part of crystal again.Yet separate the initial molecule chain and keep they not with the energy of the state of other molecules, in this technical process, be big, its stops finishes crystallization.For this energy is provided, with 1000 ℃ temperature, need, or with 600 ℃ temperature, need were with tens of hours with several minutes.Because time and temperature (=energy) have exponential relationship, for example, be lower than 600 ℃ or at 550 ℃, more almost can't see the progress of crystallization reaction.The notion of solid phase epitaxy crystallization can not give any answer to this problem.

Inventor of the present invention considers, reduces prevention energy in the aforementioned technical process with some catalytic action, and it is different from conventional solid phase crystallization notion fully.The present inventor mentions: nickel (Ni), iron (Fe), cobalt (Co), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), gold (Au) and silver (Ag) are easy to be coupled with silicon.

For example, the present inventor points out that with regard to nickel, it is easy to make the lattice constant of its lattice constant of nickle silicide (NiSix, 0.4≤X≤2.5) near silicon crystal.So, when simulation in ternary system-crystalline silicon nickle silicide amorphous silicon energy and during other condition, can observe, with the border of nickle silicide on, amorphous silicon is easy to reaction, and following reaction approximately takes place:

Amorphous silicon (silicon A)+nickle silicide (silicon B)

→ nickle silicide (silicon A)+crystalline silicon (silicon B)

(position of silicon A and silicon B indication silicon)

The potential energy that stops this reaction is low-down, and reaction temperature also is low.This reaction equation indicates, and when amorphous silicon is changed into crystalline silicon by nickel, carries out this reaction.Can find that in fact this reaction originates in below 580 ℃, even also can observe this reaction at 450 ℃.Certainly, temperature is high more, and the speed of reaction progress is fast more.With other above-mentioned metallic element, also can see identical effect.

According to the present invention; one of formation earlier contains film, particle or the agglomerate of a kind of element among Ni, Fe, Co, Ru, Rh, Pd, Os, Ir, Pt, Sc, Ti, V, Cr, Mn, Cu, Zn, Au and the Ag at least; as island, strip, wire, point-like or membranaceous nickel or above-mentioned other simple metal substrate or their silicide; as starting point; again by above-mentioned reaction; around those metallic elements are expanded to from point, crystalline silicon region is extended.In addition, oxide is unsuitable for doing to contain the material of those metallic elements, because oxide is a kind of stable compound, can not start previous reaction.

The structure of the crystalline silicon that extends from a specified point, though be different from conventional solid-phase epitaxial growth, it approaches monocrystalline silicon, the continuity of crystallization is good, thereby suitable as semiconductor device, as TFT.Yet, when materials such as comprising the aforementioned metal of quickening crystallization such as nickel evenly was arranged on the substrate, the starting point of numerous crystallization can appear, therefore be difficult to obtain the good film of crystallinity.

When hydrogen lower as the concentration in the amorphous silicon of crystallization parent material, resulting result is better.Yet, because when crystallization makes progress, can discharge hydrogen, thus do not find out in resulting silicon fiml hydrogen concentration and as the clearly correlation between the hydrogen concentration in the amorphous silicon of parent material.Hydrogen concentration in the crystalline silicon of the present invention generally is higher than 0.001at%, is lower than 5at%.

Though Ni, Fe, Co, Ru, Rh, Pd, Os, Ir, Pt, Sc, Ti, V, Cr, Mn, Cu, Zn, Au and Ag are used to the present invention, these materials generally are not suitable as the silicon of semi-conducting material, thereby must remove these materials.About nickel, because the nickle silicide that reaches as the termination of previous reaction result's crystallization is dissolved in hydrofluoric acid or hydrochloric acid or their dilution easily, use those acid treatments, nickel is reduced from substrate.Have, after crystallization process ends, in chloride atmosphere, through 400-600 ℃ processing, can reduce those metallic elements really, chloride thing is as the chloromethane (CH of hydrogen chloride, variation ₃Cl, CH ₂Cl ₂, CHCl ₃), the athylis chloridum (C that changes ₂H ₅Cl, C ₂H4Cl ₂, C ₂H ₃Cl ₃, C ₂H ₂Cl ₄, C ₂HCl ₅) or the ethlyene dichloride (C that changes ₂H ₃Cl, C ₂H ₂Cl ₂, C ₂HCl ₃).Particularly trichloroethylene is a kind of easy-to-use material.Ni, Fe, Co, Ru, Rh, Pd, Os, Ir, Pt, Sc, Ti, V, Cr, Mn, Cu, Zn, Au and the Ag concentration in silicon fiml of the present invention generally is higher than 0.005at%, is lower than 1at%.

It according to the present invention semiconductor element, TFT for example, in the use of the crystalline silicon film of making, preferably not at the terminal (also being the position that is connected mutually from the crystallization that a plurality of starting points begin) of crystallization preparation semiconductor element, can understand from top explanation, promptly be because exist big grain boundary (the discontinuous position of crystallinity) also because quicken the metallic element of crystallization, as the concentration height of nickel.So, when utilizing the present invention to form semiconductor element, must select the best metallic element that will become the crystallization starting point and quicken crystallization that comprises, as nickel by the figure of the figure of overlay film and semiconductor element.

In the present invention, the metallic element that roughly has two kinds of methods to will speed up crystallization is made figure.First method is before forming amorphous silicon film, will be that a little metals form film and analog selectively, and second method is after forming amorphous silicon film, makes those metals form film and analog selectively.

First method can realize with the conventional photoetching process or the method for peeling off.Second method is some complexity more or less.That is, if the metal film or the analog of formed acceleration crystallization depend on amorphous silicon film, when film formed, metal and amorphous silicon are local to be reacted to each other, and produces silicide.Thereby, when after forming metal film or analog, making figure, must the general corrosion silicide layer.

By second method, the stripping means ratio is easier to implement.In the case, organic material, as photoresist, or inorganic material, can be used as mask material as silica or silicon nitride.When selecting mask material, must consider treatment temperature.In addition, the effect of mask is also different because of material, must pay close attention to it whole-heartedly.Particularly, if film is not thick fully, the silica or the silicon nitride film that form with various CVD methods have many pin holes, thereby crystallization may be to launch from undesirable position.

Usually be after forming by overlay film, implement needle drawing, so that expose the surface of amorphous silicon selectively with these mask materials.Then, form metal film or the analog that quickens crystallization.

Must be noted that the concentration of metallic element in silicon fiml among the present invention.Little no more than tenor well again, also be vital but make the total maintenance of content constant.That is because if the content of metallic element has tangible fluctuating, will cause the remarkable fluctuating of degree of crystallinity of each batch lattice point of manufacturing.Special when the content that requires metallic element is littler, the fluctuating that reduces content that just becomes more difficult.

In first method,, then can not remove the latter and remove to regulate its content because metal film or the analog selecting to form are covered by amorphous silicon film.According to the content of metallic element that the present invention requires, the thickness of metal film or analog is thinned to has only number

To tens of

Thin, thereby be difficult to form this film with good reproducibility.

This is equally applicable to second method.But, compare with first method, second method still leaves some room for improvement, because in the method, the metal film or the analog that quicken crystallization are present in the surface.That is, form an enough thick metal film earlier, amorphous silicon film and metal film part are reacted, produce before the silicide, be lower than under the temperature of annealing temperature, implement a heat treatment (preannealing) in annealing.Then, erode the metal film of unreacted.Though this is relevant with used metal, particularly out of question to Ni, Fe, Co, Ti and Cr, because a kind of corrosive agent all very big to the corrosion rate of metal film and silicide arranged.

In the case, the thickness of resulting silicide is that the temperature and time by heat treatment (preannealing) is determined, and metal layer thickness is almost irrelevant with it.Therefore, the small content of the metallic element of being introduced in amorphous silicon film is may command.

The present invention also uses; when the oxidized silicon of semiconductor surface or silicon nitride coverlay (diaphragm) when covering and when making silicon metal TFT the surface not being capped when being preferably in the 500-800 ℃ of atmosphere that is containing oxygen, hydrogen or nitrogen crystallization for 450-1000 ℃, the situation that degree of crystallinity there are differences.This atmosphere can be oxygen containing atmosphere, hydrogeneous atmosphere, nitrogen-containing atmosphere, the atmosphere that contains oxygen and hydrogen, the atmosphere that contains oxygen and nitrogen, hydrogeneous and the atmosphere of nitrogen and the atmosphere that contains oxygen, hydrogen and nitrogen.Aforementioned crystallization can be undertaken by following condition: heated A hour in oxygen containing atmosphere (1), heated B hour in hydrogeneous atmosphere then; (2) in oxygen containing atmosphere, heated C hour, in nitrogen-containing atmosphere, heated D hour again; (3) heated E hour in hydrogeneous atmosphere, heated F hour in oxygen containing atmosphere, heated G hour in hydrogeneous atmosphere (4), heated H hour in nitrogen-containing atmosphere again; (5) heated I hour in nitrogen-containing atmosphere, heating is J hour in the present oxygen containing atmosphere; (6) Heating K hour in nitrogen-containing atmosphere, heating L hour in hydrogeneous atmosphere again; (7) heated M hour in oxygen containing atmosphere, heating is N hour in hydrogeneous atmosphere, heats P hour in nitrogen-containing atmosphere then; (8) heated Q hour in oxygen containing atmosphere, heating is R hour in nitrogen-containing atmosphere, heats S hour in hydrogeneous atmosphere again; (9) heated T hour in hydrogeneous atmosphere, heating is U hour in oxygen containing atmosphere, heats V hour in nitrogen-containing atmosphere again; (10) in hydrogeneous atmosphere the heating W hour, in nitrogen-containing atmosphere the heating X hour, again in oxygen containing atmosphere the heating Y hour; (11) in nitrogen-containing atmosphere, heated Z hour, in oxygen containing atmosphere, heated A ' hour, in hydrogeneous atmosphere, heated B ' hour again; Or (12) heated in nitrogen-containing atmosphere C ' hour, heated in hydrogeneous atmosphere D ' hour, heated in oxygen containing atmosphere E ' hour again.Particularly preferably heated G hour in hydrogeneous atmosphere (4), in nitrogen-containing atmosphere, heated H hour again, (5) I hour (for example 4 hours) of heating in nitrogen-containing atmosphere, in oxygen containing atmosphere, heat J hour (for example 1 hour) again, or (6) Heating K hour (for example 4 hours) in nitrogen-containing atmosphere, L hour (for example 1 hour) of heating in hydrogeneous atmosphere again.When having coverlay, in general crystallinity is good, therefore can obtain the TFT of high mobility.Yet generally its leakage current becomes remarkable.On the other hand, the advantage of the TFT of no coverlay is that leakage current is little, but crystallinity is bad, and its mobility is low, because it realizes amorphous state according to temperature.Think that its characteristic is that hydrogen, oxygen or the nitrogen that is infiltrated in the atmosphere of active layer is controlled, crystallization can be in nitrogen for example, and then realize in hydrogen or oxygen.In same substrate, same time and same technical process, form the different TFT of characteristic.For example, the TFT that preceding a kind of mobility is high can be as the drive circuit in the matrix, and the TFT that then a kind of leakage current is little can be as the TFT in the matrix.

Compare with the mobility of PMOS, perhaps can reduce the mobility of NMOS relatively, in cmos circuit, by preferred condition, diaphragm is not set on nmos area, and in the PMOS district equipment protection film, almost can eliminate difference between the two.

The temperature of thermal crystallization is an important parameter, and the crystallinity of TFT is determined by temperature in the present invention.Generally, the temperature of thermal annealing is subjected to substrate and other materials limitations.With regard to the restriction of backing material, when being used as substrate with silicon and silicon dioxide, the thermal annealing temperature can be high to 1100 ℃.For Coning7059 glass, a kind of typical alkali-free glass requires annealing temperature to be lower than 650 ℃.Yet, the present invention is based on above-mentioned reason, be necessary for each TFT, rather than be substrate, desired key character is set.When annealing temperature is high, generally can promote the growth of crystal TFT, mobility improves, and leakage current also improves.So annealing temperature should be 450～1000 ℃.Preferably 500～800 ℃, so that on same similar substrate of the present invention, obtain the TFT of different characteristic.

One embodiment of the present of invention are; in the display unit of active matrix for liquid crystal displays circuit or similar circuit; multi-crystal TFT is used as switching transistor; when making the active layer crystallization; in the active matrix district diaphragm is not set, on the other hand, cuticula is set at peripheral circuit region; make the former be transformed into the little TFT of leakage current, make the latter be transformed into the high TFT of mobility.

The rendering of a device of Fig. 8 (A) expression driving electrical equipment (peripheral circuit) that has a display circuit part (active matrix) and establish for it as previously described.In the drawings, represent a display unit, wherein settle a data driver 101 and gate driver 102, active matrix 103 of middle arrangement with TFT, door line 105 and digital line 106 by on the dielectric substrate 107 are connected these driver portion with active matrix.Active matrix 103 is the set (PMOS among the figure) with pixel unit of NMOS or PMOSTFT.

For the cmos circuit of drive part, the impurity in active layer preferably is lower than 10 as the concentration of oxygen, nitrogen and carbon ¹⁸/ cm ³, or preferably be lower than 10 ¹⁷/ cm ³, so that obtain high mobility.Consequently, the threshold voltage of TFT is 0.5～2V at NMPS for example, at PMOS be-0.5～-3V, and mobility is 30～150cm at NMOS ²/ Vs is 20～100cm at PMOS ²/ Vs.

On the other hand, employing its leakage current under the drain voltage of 1V is low to moderate the element single or each series connection of 1pA, can reduce and can further eliminate fully the auxiliary capacitor of active matrix part.

Second embodiment of the present invention relates to a semiconductor memory.A semiconductor storage unit made from monocrystalline IC reaches its speed limit already.Though, must increase transistorized current capacity, so that make it speed operation be arranged with higher, this will cause the further increase of power consumption, but can not be handled to increase driving voltage, because concerning DRAM (), the capacity of electric capacity can not increase again, it carries out memory function by stored charge in the capacitor.

Why say that monocrystalline IC has reached its speed limit, one of reason is to bring very big loss because of the electric capacity by substrate and wiring, if do substrate with insulator, need not increase power consumption can be with sufficiently high speed operation.Based on this reason, the IC of a kind of SOI of having (semiconductor on insulator) structure has been proposed.

Structure with regard to 1 transistor/unit; the circuit layout of a DRAM and the layout of aforesaid liquid crystal indicator are much at one; and be different among the DRAM of the sort of structure (for example 3 transistors/unit) on its structure; when active layer crystal body; in Memory Storage Unit (bit) part diaphragm is not set; on the contrary; diaphragm is set on drive circuit area; because require according to the method identical with the foregoing liquid crystal display unit; with sufficiently high speed operation; make the former change the little TFT of leakage current into, make the latter change the big TFT of leakage current into.

The basic combining structure of this semiconductor memory is identical with the structure shown in Fig. 8 A.For example, in DRAM, label (101) can be a column decoder, (102) be a row decoder, (103) are memory element parts, and (104) are unit storage units (bit), (105) be position (bit) line, (106) are that word line and (107) are (insulation) substrates.

The 3rd application examples of the present invention is a drive circuit that is used for image sensor or similar device, the example of 1 (bit) circuit of Fig. 8 (B) presentation image transducer, circuits for triggering 108 wherein and buffering circuit 109 generally are made of cmos circuit, and require the response speed height, so that catch up with the high-speed pulse that imposes on scan line.On the other hand, the TFT110 that is positioned at the signal output stage plays a control action, receives a signal from

shift register

108 and 109, through photoelectric diode, the electric charge that gathers is discharged into data wire.

This TFT 110 is not only required the response speed height, and require leakage current little.So, in this circuit, when

circuit

108 and 109 regional crystallizations, diaphragm to be set, make it change the TFT of high mobility into.On the contrary, when TFT 110 regional crystallizations, diaphragm must not be set, make it be transformed into the TFT of low-leakage current.

In the present invention, silica, silicon nitride or silicon oxynitride (SiNxOy) can be used as coverlay.Though film is thick more, covering performance is good more, must weigh productivity ratio and protective value, so that determine thickness, because desire forms thick film, and then must spended time.Although covering performance is different with the quality of film, in general, must be to silicon oxide thickness greater than 20nm, must be to silicon nitride thickness greater than 10nm.When taking all factors into consideration mass productivity and reliability, to silicon oxide film and silicon nitride film, its thickness preferably all is 20～200nm.

Description of drawings

Above-mentioned and other advantage of the present invention, by following explanation and accompanying drawing, it is clearer to become, in each view, the identical identical component of label representative.

Fig. 1 (A)～1 (C) is the top view of expression present embodiment (crystallization of TFT and layout);

Fig. 2 (A-1), 2 (A-2) and 2 (B)～2 (D) are the profiles of expression embodiment technology (selective freezing technology);

Fig. 3 (A)～3 (C) is the profile of expression this embodiment (seeing first embodiment) technology;

Fig. 4 (A)～4 (C) is the profile of expression this embodiment (seeing first embodiment) technology;

Fig. 5 (A)～5 (C) is the profile of expression this embodiment (seeing second embodiment) technology;

Fig. 6 (A)～6 (C) is the profile of expression this embodiment (seeing the 3rd embodiment) technology;

Fig. 7 (A)～7 (E) is the profile of expression this embodiment (seeing the 4th embodiment) technology;

Fig. 8 (A) is the block diagram that is used to the case of an active matrix apparatus as the present invention;

Fig. 8 (B) is a circuit diagram that is used to the drive circuit of an image sensor as the present invention;

Fig. 9 (A)～9 (C) is the profile of this embodiment technology of expression;

Figure 10 (A)～10 (C) is the profile of this embodiment technology of expression; And

Figure 11 (A)～11 (D) is the profile of this embodiment technology of expression.

Embodiment

Embodiment 1

To introduce in the present embodiment, and be used in each island nickel film that forms on the Coning7059 glass substrate and make starting point, make the amorphous silicon film crystallization, make the method for TFT with resulting crystalline silicon film.According to island nickel film be on the amorphous silicon film or under form, two kinds of methods that form island nickel films are then arranged.Fig. 2 (A-1) is illustrated in the method that forms the nickel film under the silicon fiml, and Fig. 2 (A-2) is illustrated in the method that forms the nickel film on the silicon fiml.To the necessary SC of back one method, because in technology, corroding nickel selectively is to form after the nickel on the whole surface of amorphous silicon film, and nickel and amorphous silicon react to each other, although its amount seldom, will produce nickle silicide.Because if nickle silicide stays same as before, the crystal silicon film that can not obtain then, being of the object of the invention must be removed nickle silicide fully with hydrochloric acid or hydrofluoric acid.Therefore, amorphous silicon is a little from the reset condition attenuation.

On the other hand, to the previous case,, in the case, except that the island part, also remove the nickel film fully with etch though do not cause this problem.With oxygen plasma or ozone treatment substrate, make the nickel oxidation in addition of island district, can get rid of the influence of residual nickel.

No matter any situation is all used the plasma CVD method, going up formation thickness at substrate 1A (Coning7059) is 2000

Bottom silicon oxide film 1B.Be equipped with amorphous silicon film 1, thick 200～3000 with plasma CVD method or vacuum C VD legal system

, preferred 500～1500

The base 350～450 ℃ annealing 0.1～2 hour dehydrogenation, remain on the concentration of hydrogen in the film below the 5at% after, make the amorphous silicon film crystallization easily.

With regard to Fig. 2 (A-1), be before forming amorphous silicon film 1, make the nickel film be stacked into 50-1000 with sputtering method

, preferred 100-500

Needle drawing forms island nickel district 2 again.

With regard to Fig. 2 (A-2), then opposite, be after forming amorphous silicon film 1, make the nickel film be stacked into 50-1000 with sputtering method

, preferred 100-500

, needle drawing forms island nickel district 2 again.Figure 1A represents above-mentioned state.

Each island district nickel is the square of 2 * 2 μ m, is set at interval 5-50 μ m or 20 μ m for example.Replace nickel with nickle silicide, also obtained same effect.In the time will forming nickel, substrate is heated to 100-500 ℃, preferred 180-250 ℃, can obtain good result.That is because improved the adhesion of bottom nickel silicide layer and nickel film, also because produce nickle silicide by silica and nickel reactant, replaces silica also can obtain identical effect with silicon nitride, carborundum or silicon.

Then in nitrogen atmosphere 450-580 ℃ or for example 550 ℃ annealing 8 hours.This annealing also can be carried out in nitrogen and hydrogen mixed atmosphere.Perhaps, this annealing can be carried out in hydrogen atmosphere X1 hour, carried out in blanket of nitrogen X2 hour then.Fig. 2 (B) represents the intermediateness of this technology, and nickel wherein is advanced to the edge near the center from island nickel district 2, become nickle silicide 3A, and the position 3 that nickel has passed through has become crystalline silicon.Shown in Fig. 2 (C), be connected from two initial crystallizations of island nickel film, and nickle silicide 3A stays the centre, thereby crystallization finishes then.

The substrate of Fig. 1 (B) expression from this state, wherein the nickle silicide among Fig. 2 (C) is the border 4 of intergranular.When continuing annealing, nickel 4 moves along the grain to grain boundary, assembles the mesozone 5 (though not keeping their original shapes under this state) in island nickel district.

Can obtain crystalline silicon with above-mentioned technology, but not wish that nickel is diffused into the semiconductor coat film from the nickle silicide that produces at this moment.The zone that the nickel height gathers is eliminated in the most handy hydrochloric acid or hydrofluoric acid corrosion.Have, because the corrosion rate of nickel and nickle silicide is very big, with hydrochloric acid or hydrofluoric acid corrosion the time, silicon fiml is unaffected again.Remove the former zone that the growing point of nickel is set simultaneously.State after Fig. 2 (D) expression corrosion.A groove 4A is changed at the position of being originally the grain to grain boundary into.This is undesirable to the zone (active layer or similar layer) that forms semiconductor TFT, so that will shrink this groove.Shown in Fig. 1 (C), do not make semiconductor region 6 stride across grain to grain boundary 4 and come layout TFT.That is,, or not do not form TFT in the crystal growth district under the nickel effect at the thickness direction of coat film in the horizontal direction of parallel substrate.Crystal growth direction should be evenly arranged, also residual nickel should be dwindled as far as possible.On the other hand, grid line 7 can be crossed over grain to grain boundary 4.

Fig. 3 and Fig. 4 represent that the crystalline silicon that obtains with above-mentioned technology makes the method embodiment of TFT.In Fig. 3 (A), be originally the place of groove 4A in the middle label character X indicator diagram 2, as shown in the figure, when layout semiconductor TFT zone, can not stride across the X position.That is, the resultant crystalline silicon film composition of technology shown in Figure 2 is formed island semiconductor district 11a and 11b.Yet, use such as RF plasma CVD, ECR plasma CVD or sputter formation silicon oxide film 12 as gate insulating film.

Further, mix 1 * 10 with vacuum C VD method ²⁰～5 * 10 ²⁰/ cm ³Phosphorus, form thick 3000～6000

Polysilicon film, then with its pie graph (Fig. 3 (A)), form gate electrode 13a and 13b.

Then, mix impurity with plasma doping method.As for impurity gas,, use hydrogen phosphide (PH to N type TFT ₃), to p type TFT, use diborane (B ₂H ₆).To the hydrogen phosphide accelerating voltage is 80KeV, is 65KeV to diborane.550 ℃ of annealing 4 hours, activator impurity was to form impurity range 14a to 14b.Use luminous energy,, also can be used for activating (Fig. 3 (B)) as the method for laser annealing or flash lamp annealing.

At last, deposit one bed thickness 5000

Silicon oxide film as interlevel insulator 15, similar with the situation of normal making TFT, connecing by this layer formation can the hole, forms wiring and electrode 16a～16d in source and drain region.

TFT (N ditch type among the figure) presses above-mentioned prepared.The field-effect mobility of resulting TFT is 40～60cm in N ditch type ²/ Vs is 30～50cm in P ditch type ²/ Vs.

Fig. 4 represents how to prepare the technology of alum gate TFT.In Fig. 4 (A), middle label character X indicates the place of groove 4A among the former Fig. 2 of being.Setting to the semiconductor TFT zone should not stride across the X position.That is, will form island semiconductor district 21a and 21b by crystalline silicon film 3 compositions that technology shown in Figure 2 obtains.Then, use such as RF plasma CVD, ECR plasma CVD or survey shooting method and form the silicon oxide film 22 that cuts off film as grid.When with TEOS (tetrem oxosilane) and oxidation original gas doping plasma CVD method, can obtain satisfied effect.Then, sputtering deposit contains the aluminium film (thick 5000 of 1% silicon

), composition forms grid lead and electrode 23a and 23b again.

Then, substrate is immersed in the 3% tartaric ethylene glycol solution, nickel is set as negative electrode, aluminum steel is made anode, passes to electric current at the two again, implements anodic oxidation.Originally increase its voltage by the 2V/ branch and apply electric current, when reaching 220V, voltage is fixed.When electric current becomes less than 10 μ A/M ², stopping energising, the result forms thick 2000 shown in Fig. 4 (A)

Anodic oxide coating 24a and 24b.

Mix impurity with plasma doping then.About impurity gas, to N type TFT hydrogen phosphide (PH ₃), to P type TFT diborane (B ₂H ₆).Accompanying drawing is represented N type TFT.To the hydrogen phosphide accelerating voltage is 80KeV, is 65KeV to diborane.Use the laser annealing activator impurity, form impurity range 25a to 25d.Used laser is KrF laser (wavelength 248nm), is 250～300mJ/cm with energy density ² Laser pulse irradiation 5 times (Fig. 4 (B)).

At last, deposit thick 5000

Silicon oxide film, as interlevel insulator 26, be similar to the situation of normal preparation TFT, by this layer formation contact hole, so that the wiring in formation source and drain region and electrode 27a～27d (Fig. 4 (C)).

The field rate of moving of resulting TFT is to be 60～120cm in N ditch type ²/ Vs, TFT is 50～90cm in P ditch type ²/ Vs.In the shift register of making of this kind TFT, confirm drain voltage at 17V, be operated in 6MHz, be operated in 11MHz at the 20V drain voltage.

Embodiment 2

Fig. 5 represents a kind of situation of making alum gate TFT, to shown in Figure 4 similar.Yet in this embodiment, amorphous silicon is used as active layer.Shown in Fig. 5 (A), deposit one bed thickness 2000～3000 on substrate 31

Amorphous silicon film 33.In amorphous silicon film, can sneak into an amount of P type or N type impurity.Form island nickel or nickle

silicide coat film

34A and 34B by the above, under this state,, or, make the amorphous silicon film cross growth and crystallization 600 ℃ of annealing 4 hours 550 ℃ of annealing 8 hours.

Then, with the figure of crystalline silicon film formation shown in Fig. 5 (B) that so obtains, at this moment, because the silicon fiml of middle part in the drawings (middle part between nickel or nickel silicide film 34A and the 34B) contains nickel is arranged in a large number, when implementing needle drawing, remove this position, to form island silicon area 35A and 35B.Then, the deposit amorphous silicon film 36 of intrinsic basically more thereon.

After this, shown in Fig. 5 (C), use material to form one deck coat film, make this gate insulating film 37 such as silicon nitride or silica.Form gate electrode 38 with aluminium, use the method identical to implement anodic oxidation again with Fig. 4 situation.Use the ion doping method diffusion impurity then, to form impurity range 39A and 39B.And then deposit interlevel insulator 40, form contact hole and

form metal electrode

41A and 41B in the drain region in source, finish TFT.This TFT is characterised in that the semiconductor film at source and leakage position is thick, and its impedance is little.Its result has reduced the impedance in source and drain region, has improved the feature of TFT.Have, contact may form contact hole easily again.

Embodiment 3

Fig. 6 represents to make the technical process of CMOS type TFT.Shown in Fig. 6 (A), deposit one bottom silicon oxide film 52 on substrate 51, one bed thickness 1000～1500 of deposit thereon again

Amorphous silicon film 53.Then as mentioned above, form island nickel or nickle silicide coat film 54, implement annealing at 550 ℃ at this state.Nickel silicide region 55 is along the in-plane of coat film, rather than the thickness direction displacement, advances crystallization with this technology.Annealed 4 hours, and made amorphous silicon film become crystalline silicon shown in Fig. 6 (B).

Nickel silicide region

59A and 59B are along with the propelling of crystallization is pushed to the edge.

With the island silicon area 56 of crystalline silicon film composition formation shown in Fig. 6 (B) that so obtains.Here answer SC, nickel highly is collected at the two ends in island district.After forming the island silicon area, form gate insulating film 57 and

gate electrode

58A and 58B.

Then, form N type impurity range 60A and p type impurity district 60B with the ion doping method diffusion impurity, shown in Fig. 6 (C).At this moment, can (impurity gas be hydrogen phosphide PH as N type impurity with phosphorus ₃) mix, make to mix with the accelerating voltage of 60～110KeV to spread all over whole surface, cover N ditch type TFT district then with photoresist, afterwards more for example, (impurity gas is diborane B as p type impurity with boron ₂H ₆), the accelerating voltage with 40～80KeV mixes again.

After the doping,, source and drain region are activated with the laser irradiation that is similar to Fig. 4 situation.Then, deposit interlevel insulator 61 forms contact hole and forms

metal electrode

62A, 62B and 62C in source and drain region again, makes TFT.

Embodiment 4

Fig. 7 represents the 4th embodiment.Present embodiment relates to a kind of method, wherein, with heat treatment for the first time (preannealing) part of nickel film and amorphous silicon film is reacted, and after removing unreacted nickel film, annealing makes the amorphous silicon membranization again, produces silicide.

On substrate (Coning No.7059) 701, form a bottom silicon oxide film 702 (thick 2000 with sputtering method

).Then, form a bed thickness 300～800

, for example thick 500

Silicon fiml 703.Form one deck silicon oxide film 704 with plasma CVD method again.This silicon oxide film 704 is as mask material, and its thickness is preferably 500～2000

If too thin, because of pin hole makes crystallization from unexpected local the expansion,, to spend more time for forming thick film if too thick, this is unsuitable for producing in batches.Thereby be located at 1000 here

Afterwards, use known photoetching process, with silicon oxide film 704 compositions.Form one deck nickel film 705 (thick 500 with sputtering method then

).The thickness of nickel film 705 cans be compared to 100 most

Thick [Fig. 7 (A)].

Then, make it in nitrogen atmosphere, 250～450 ℃ (a kind of preannealing technology) annealing 10～60 minutes.For example, 450 ℃ of annealing 20 minutes.As a result, in amorphous silicon, form one deck nickle silicide 706.The thickness of this layer is by the decision of the temperature and time of preannealing, and almost with the thickness irrelevant (Fig. 7 (B)) of nickel film.

Afterwards, corrode this nickel film.Nitric acid or hydrochloric acid solution are applicable to this corrosion.In with these corrosive agent corrosion nickel membrane process, nickel silicide layer is not corroded.In the present embodiment, use a kind of corrosive agent that in nitric acid, adds as the acetate of buffer.Its proportioning is: nitric acid: acetate: water=1:10:10.After removing the nickel film, at 4～8 hours (a kind of crystallization annealing process) of 550 ℃ of annealing.

In the crystallization annealing process, tried several methods.First method shown in Fig. 7 (C), when implementing this technology, keeps mask material 704 simultaneously.Crystallization is pressed Fig. 7 (C) arrow direction and is advanced.Second method is to anneal after exposing silicon fiml removing all masks.The third method is after removing mask material, forms after the new coat film of being made up of silica or silicon nitride 707 as diaphragm on silicon fiml, anneals, shown in Fig. 7 (D).

Though first method is simple, the surface of mask material 704 is in the reaction of preannealing step and nickel, and becomes silicide in the crystallization annealing process of higher temperature, almost can not corrode.That is, because the corrosion rate of silicon fiml and mask material 704 is almost equal, for after mask material removes, the position that silicon fiml is exposed also is corroded in a large number, produces step on substrate.

Second method is very simple, is easy to corrode, because before the crystallization annealing process, the reaction of mask material and nickel is slight.Yet when carrying out crystallization annealing, silicon face is exposed fully, and the characteristic of TFT of Zhi Zaoing or analog will degenerate afterwards.

Though the third method can stably obtain the gem-quality crystal silicon fiml.But very complicated, because increase some technical processs.As for the 4th kind of method, be a kind of remodeling of the third method, this method comprises: under the state that silicon face is exposed, put into a stove, earlier logical oxygen is about 1 hour of 500～550 ℃ of heating, so that form thick 20～60 on the surface

The thin silicon oxide film, change logical nitrogen into as discussion to the crystallization annealing conditions.According to this method, form oxide-film at the crystallization initial period.But this oxidation stage only near nickel silicide film by crystallization, afterwards will be as the district (position, right side among the figure) of TFT, not by crystallization.Therefore, be very smooth on surface away from the regional silicon fiml of nickel silicide layer 706.Characteristic is improved many than second method, almost equal with the third method.

Crystalline silicon film obtains like this.Hereafter,, remove high position of nickel concentration (zone of growth sintering is set) and production (the oblique line position of arrow end in the drawings) simultaneously, only keep the low zone of nickel concentration simultaneously silicon fiml 703 compositions.By the above, formation will be used for the island silicon area 708 of TFT active layer.Form thick 1200 with plasma CVD then

By the gate insulating film 709 that silica constitutes, cover zone 708.Use thick 6000 again

Mix the wiring 711 that the phosphorus silicon fiml forms gate electrode 710 and ground floor, make mask with gate electrode 710, with self-aligned manner, impurity is injected active layer 708, formation source/drain region 712.Using visible or near-infrared high light irradiation then, is effective to improving crystallization.Form thick 6000 with plasma CVD method again

Silicon oxide film do interlevel insulator 713.At last, in interlevel insulator, make contact hole, use thick 6000 again

The aluminium film form second wiring 714, the source/drain electrode wiring 715 of holding concurrently.Finish TFT (Fig. 7 (E)) with above-mentioned technology.

Embodiment 5

Fig. 9 represents present embodiment.In the present embodiment, in the active matrix district and peripheral circuit of TFT type liquid crystal indicator, form multi-crystal TFT.

At first, on glass substrate that heat-resisting character is arranged such as quartz glass 120, use sputtering method, the underlying oxide film 121 of the thick 20～200nm of deposit.Do raw material with monosilane or disilane again, with plasma CVD method or vacuum C VD method.The amorphous silicon film of deposit 30～50nm thereon.Here, oxygen or the nitrogen concentration in amorphous silicon film is lower than 10 ¹⁸/ cm ³, be preferably lower than 10 ¹⁷/ cm ³In the present embodiment, the concentration of oxygen is arranged on is lower than 10 ¹⁷/ cm ³On amorphous silicon film, form the silicon nitride film of the silicon oxide film of thick 100-150nm or thick 30-100nm as coverlay with sputtering method.Composition then only stays the coverlay 122 of peripheral circuit region.Then, (600 ℃) were preserved 4-100 hour in the atmosphere of the argon of oxygen that contains 20-100vol% or hydrogen or nitrogen, made its crystallization.As a result, the crystallinity of the silicon fiml 123A of peripheral circuit region is good, and the crystallinity of the silicon fiml 123B of pixel region is bad.Fig. 9 (A) illustrates this state.

Next, silicon fiml is constituted being used to form peripheral circuit TFT district 124A and being used to form the island of pixel TFT district 124B as Fig. 9 (B) shown in.Form gate oxidation films 125 with sputtering method or similar approach then.The plasma CVD method of this available TEOS (tetrem oxosilane) replaces sputtering method to form.When forming this film with TEOS, be preferably in form in the middle of or afterwards, be higher than 650 ℃ annealing temperature 0.5-3 hour.

After this, form the N-type silicon fiml of thick 0.2-2 μ m with the LPCVD method, and, form gate electrode 126A-126C in each island district with its formation figure.Metal material with better heat resistance can be used to replace such as tantalum, chromium, titanium, tungsten and molybdenum.

Then, partly make mask,, use the ion doping method, impurity is injected the island silicon fiml of each TFT with self-aligned manner with gate electrode.At this moment, at first adopt hydrogen phosphide (PH ₃) make impurity gas, phosphorus is injected whole surface, the right side of (not shown) coverage diagram Zhong Dao district 124A and matrix district with photoresist adopt diborane (B afterwards then ₂H ₆) make impurity gas, boron is injected into the island district 124A in left side.The dosage of phosphorus is set to 2-8 * 10 ¹⁵/ cm ², and the dosage of boron is 4-10 * 10 ¹⁵/ cm ², so the dosage of boron should surpass the dosage of phosphorus.So just produce a p type island region 127A and N-type district 127B and 127C.

Activated it in annealing temperature 2-4 between 550 and 750 ℃ hour.In the present embodiment, carried out thermal annealing 24 hours at 600 ℃.This annealing process has activated ion implanted region.

Can finish this technology with laser annealing.Because when using laser annealing, little to the fire damage of substrate, so can use common alkali-free glass, for example, Conign 7059.In addition, the material of available poor heat resistance such as aluminium are made gate material.P type island region 127A and N-type district 127B and 127C have been produced by above-mentioned technology.The sheet resistance in these districts is 200-800 Ω/.

After this, with the silicon oxide film of sputtering method, as interlevel insulator 128 at the thick 300-1000nm of whole surface formation.This can be the silicon oxide film that forms with plasma CVD method.Use plasma CVD method.Particularly make raw material, can obtain ladder and cover good silicon oxide film with TEOS.

Produce one deck ITO film with sputtering method then, composition forms pixel capacitors 129 again.In the TFT source/and leakage (impurity range) generation contact hole, to form the wiring 130A-130E that titanium nitride or chromium are made.Fig. 9 (C) expression produces Nverter circuit with the NTFT and the PTFT in left side.Wiring 130A-130E can be that titanium nitride or chromium are the aluminium multilayer wiring of bottom, so that reduce sheet resistance.At last, in hydrogen, 200-350 ℃ of annealing 0.5-2 hour, to reduce the dangling bonds of silicon active layer.Peripheral circuit and active matrix circuit can be integrated together.In the present embodiment, in peripheral circuit portion, typical mobility is 80cm to NMOS ²/ Vs is 50cm to PMOS ²/ vs, and in pixel TFT (NMOS), mobility is 5-30cm ²/ vs.

Embodiment 6

Figure 10 represents present embodiment.In the present embodiment, adopt the present invention to reduce mobility poor of NMOS in the cmos circuit and PMOS.

At first, use the underlying oxide film 132 of sputtering method thick 20-200nm of deposit on Coning7059 substrate 131.Make raw material with monosilane or Z silane, with plasma CVD method or vacuum C VD method, the amorphous silicon film of the thick 50-250nm of deposit thereon again.In amorphous silicon film, be lower than 10 at the bottom of the concentration of oxygen or nitrogen ¹⁸/ cm ³Or be preferably lower than 10 ¹⁷/ cm ³For this purpose, vacuum C VD method suits.Among the present invention, oxygen concentration is set to be lower than 10 ¹⁷/ cm ³

Coverlay 133 (silicon oxide film of thick 50-150nm) is set in the PMOS district.Then argon gas containing oxygen more than 50% or the atmosphere of the nitrogen of hydrogen in, made it crystallization in 4-100 hour 600 ℃ of annealing.Its result, though the crystallinity of the regional 134A under coverlay is good, the regional 134B crystallinity of not having coverlay is bad.Figure 10 (A) expresses this kind state.

Then, silicon fiml is constituted island, so that form PMOS district 135A and nmos area 135B, shown in the composition 10 (B).

Form the silicon oxide film 125 of thick 50-150nm then with sputtering method, cover these island districts as gate insulating film 136.Form the aluminium film of thick 0.2-2 μ m then with sputtering method, and composition forms gate electrode.In electrolyte, give its transmission of electric energy, on gate electrode, form anode oxide film with the side.Form gate electrode part 137A and 137B with above-mentioned technology in each island district.

Then, use the ion doping method, partly make mask with self-aligned manner, impurity is injected the island silicon fiml of each TFT with gate electrode.At this moment, at first use hydrogen phosphide (PH ₃) make impurity gas, phosphorus is injected whole surface, the island district 135B in the coverage diagram only with photoresist is with diborane (B ₂H ₆) make impurity gas, boron is injected island district 135A.The dosage of phosphorus is set to 2-8 * 10 ¹⁵/ cm ², the dosage of boron is set to 40-10 * 10 ¹⁵/ cm ², so that the dosage of boron surpasses the dosage of phosphorus.

Though the doping process has been destroyed the crystallinity of silicon fiml, its sheet resistance still can remain on about 1K Ω/.Yet,, 600 ℃ of annealing 2-4 hour, can fall sheet resistance again if the sheet resistance of this kind degree is also high.Can obtain same effect with high light or laser irradiation.

P type island region 138A and N-type 138B have so just been formed.The sheet resistance in these districts is 200-800 Ω/.The silicon oxide film that forms thick 300-1000nm with sputtering method on whole surface is made interlevel insulator 139 then.This can be the silicon oxide film that forms with plasma CVD method.Particularly make raw material with the plasma CVD method, can obtain ladder and cover good silicon oxide film with TOES.

Source/leakage (impurity range) at TFT forms contact hole then, to form aluminium wiring 140A-140D.At last, the 250-350 in hydrogen ℃ annealing temperature 2 hours is to reduce the dangling bonds of silicon fiml.The typical mobility of the TFT that obtains with above-mentioned technology is 60cm to PMOS and NMOS ²/ vs.When making shift register, confirm under the drain voltage of 20V, to be operated in more than the 10MHz with technology of the present invention.

Embodiment 7

Figure 11 represents present embodiment.Present embodiment relates to the circuit that transistor and silicon resistor combine.Silicon with doping impurity can be used as transistorized protective circuit.At first, use the end oxide-film of sputtering method thick 20-200nm of deposit on Coning7059 substrate 140.With plasma CVD method or vacuum C VD method, do former condiments with monosilane or disilane, the amorphous silicon film of the thick 100-250nm of deposit more thereon.Here, in amorphous silicon film, the concentration layer of oxygen or chlorine is lower than 10 ¹⁸/ cm ³, or be preferably lower than 10 ¹⁷/ cm ³

The silica of deposit 20-200nm covers 143, and in the atmosphere of argon or nitrogen, 600 ℃ of annealing 4-100 hour, makes its crystallization.Figure 11 (A) expresses this state.

Below, silicon fiml is constituted island, to form transistor area 144A and resistance area 144B, shown in Figure 11 (B).The silicon oxide film that forms thick 50-150nm with sputtering method covers those island districts and makes gate insulating film 145 then.Then, form the aluminium film of thick 0.2-2 μ m with sputtering method, composition forms gate electrode again.Give the aluminium film transmission of electric energy in electrolyte, form the cathode oxidation film in the top and the side of gate electrode.With above-mentioned technology, in each island district, form gate electrode part 146.

Then, partly make mask,, use the ion doping method,, be injected into the island silicon fiml of each TFT as phosphorus impurity with self-aligned manner with gate electrode.The dosage of phosphorus is 2-8 * 10 ¹⁵/ cm ²

Form

impurity range

147A and 147B with above-mentioned doping process.Because identical impurity level is injected into two doped regions.When according to reality require thermal annealing the time, they express identical resistivity.Yet situation but is, for example when resistance that the latter is had relatively high expectations, and instead the former require lower resistance.Then, only in transistor area, shown in Figure 11 (C), form the silica coverlay 148 of thick 50-150nm.In the atmosphere that contains greater than the nitrogen of the oxygen of 50vol% or hydrogen or argon,, annealed 4-20 hour then 550-650 ℃ temperature.Available hydrogen phosphide replaces oxygen or hydrogen.Yet annealing temperature is preferably lower than 800 ℃, if because annealing temperature is too high, hydrogen phosphide will be thermal decomposited, and be diffused in the semiconductor, reduce resistivity on the contrary.When the resistance area of impurity is the P-type, can use diborane (B ₂H ₆).

With top technology, when the sheet resistance of transistorized impurity range was 20-800 Ω/, the sheet resistance of the impurity range of resistance was 2K-100 Ω/.On whole surface, form the silicon oxide film of thick 300-1000nm with sputtering method, as interlevel insulator 149.This can be the silicon oxide film that forms with plasma CVD method.Use plasma CVD method, particularly make raw material, can obtain covering the good silicon oxide film of ladder with TEOS.

Source/leakage (impurity range) at TFT forms contact hole, to form aluminium wiring 150A-150C.At last, in hydrogen at 250-350 ℃ of annealing temperature 0.5-2 hour.So that reduce the silicon fiml dangling bonds.It is identical to distinguish its thickness through above-mentioned technology, the sheet resistance in the zone that the impurity injection rate is identical.

As mentioned above, say in some sense that the present invention is an epoch-making invention, this has promoted amorphous silicon to realize crystallization at lower temperature and short period, and provides immeasurable benefit for industry.Because used facility, instrument and technology are very common, then be very good to producing in batches.Though in the foregoing embodiments, emphatically nickel is explained, and same technology is quickened the metallic element of crystallization, for example arbitrary element element among Fe, Co, Ru, Rh, Pd, Os, Ir, Pt, Sc, Ti, V, Cr, Mn, Cu, Zn, Au and the Ag applicable to other.

For example, suppose that handling a slice substrate must spend two minutes, and in conventional solid state growth method, need 15 annealing furnaces, because need 24 hours annealing at least.The present invention can make the number of annealing furnace reduce to less than 1/6, because annealing time can shorten to 4 hours or the shorter time.And therefore and the rising of the new demand of coming because the decline of substrate processing cost, and the decline of TFT cost, with the reduction of the raising of this productivity ratio, equipment investment.So the present invention is very favourable to industry, should patent in the nature of things.

In addition, the present invention changes one with the minimum of TFT active layer crystallization condition or does not have coverlay, has solved the difficult problem in the conventional silicon metal TFT production technology.

The present invention especially can improve dynamic circuit and have the reliability and the performance of the device of this circuit.Generally, though concerning the active matrix of liquid crystal display, the ON/OFF of silicon metal TFT is than being low, and no matter how all to be difficult to drop into practical, it is considered herein that this class problem is solved.Though do not show with embodiment, very clear, when enforcement is of the present invention, can be effective as the device of implementing three-dimensional single crystal semiconductor integrated device with TFT.

For example, make peripheral logical circuit on the brilliant semiconductor of available semiconductor circuit notice of invitation, and, TFT is set thereon, constitute the memory element part by the interlevel insulator intermediary.In the case, the memory element part can be the DRAM circuit that utilizes TFT of the present invention, and their drive circuits are to be made of the CMOS that is made into the single crystal semiconductor circuit.Have again, when this kind circuit is used to microprocessor, can save its area,, think that the present invention is of great use invention to industry because can make memory portion on the upper strata.

Though represent especially and introduced the present invention with reference to its preferred embodiment, it will be apparent to those skilled in the art that, can carry out above-mentioned change with other in form and details, still should not break away from spirit of the present invention and category.

Claims

1. the manufacture method of a semiconductor device may further comprise the steps:

On substrate, form amorphous silicon film;

Be provided for quickening the metallic element of crystallization for amorphous silicon film;

Make the described amorphous silicon film crystallization that has been provided the metallic element that is used to quicken crystallization;

On the silicon fiml of crystallization, form gate insulating film;

On gate insulating film, form the first grid electrode and second gate electrode;

In the silicon fiml of crystallization, form a pair of first impurity range and a pair of second impurity range; And

Form and this one and this wiring that is electrically connected second impurity range to first impurity range,

Wherein, this to first impurity range described one with should contact described of second impurity range.

2. the manufacture method of semiconductor device according to claim 1, wherein, this metallic element that is used to quicken crystallization comprises nickel.

3. the manufacture method of semiconductor device according to claim 1, wherein, this is made up of phosphorus first impurity range.

4. the manufacture method of semiconductor device according to claim 1, wherein, this is made up of boron second impurity range.

5. the manufacture method of semiconductor device according to claim 1 also comprises step: after formation should and be somebody's turn to do second impurity range to first impurity range, with the silicon fiml of laser radiation crystallization.

6. the manufacture method of semiconductor device according to claim 1, wherein this crystallization step is to carry out with the temperature from 500 ℃ to 800 ℃.

7. the manufacture method of semiconductor device according to claim 1 also comprises step: after crystallization step, the concentration that is used to quicken the metallic element of crystallization in the silicon fiml with crystallization reduces.

8. the manufacture method of a semiconductor device may further comprise the steps:

On substrate, form amorphous silicon film;

On the silicon fiml of crystallization, form gate insulating film;

Wherein, this to first impurity range described one with should contact described of second impurity range, and

Wherein, in the two ends of the silicon fiml of this crystallization, this metallic element that is used to quicken crystallization is in high concentration.

9. the manufacture method of semiconductor device according to claim 8, wherein, this metallic element that is used to quicken crystallization comprises nickel.

10. the manufacture method of semiconductor device according to claim 8, wherein, this is made up of phosphorus first impurity range.

11. the manufacture method of semiconductor device according to claim 8, wherein, this is made up of boron second impurity range.

12. the manufacture method of semiconductor device according to claim 8 also comprises step: after formation should and be somebody's turn to do second impurity range to first impurity range, with the silicon fiml of laser radiation crystallization.

13. the manufacture method of semiconductor device according to claim 8, wherein this crystallization step is to carry out with the temperature from 500 ℃ to 800 ℃.

14. the manufacture method of semiconductor device according to claim 8 also comprises step: after crystallization step, the concentration that is used to quicken the metallic element of crystallization in the silicon fiml with crystallization reduces.

15. the manufacture method of a semiconductor device may further comprise the steps:

On substrate, form amorphous silicon film;

On the silicon fiml of crystallization, form gate insulating film; And

On gate insulating film, form gate electrode,

In the two ends of the silicon fiml of crystallization, this metallic element that is used to quicken crystallization is in high concentration.

16. the manufacture method of semiconductor device according to claim 15, wherein, this metallic element that is used to quicken crystallization comprises nickel.

17. the manufacture method of semiconductor device according to claim 15 also comprises step: form interlevel insulator on gate electrode.

18. the manufacture method of semiconductor device according to claim 15, wherein, these two ends comprise silicide.

19. the manufacture method of semiconductor device according to claim 15, wherein this crystallization step is to carry out with the temperature from 500 ℃ to 800 ℃.

20. the manufacture method of semiconductor device according to claim 15 also comprises step: after crystallization step, the concentration that is used to quicken the metallic element of crystallization in the silicon fiml with crystallization reduces.