CN100470739C - Portal information terminal and vedio camera - Google Patents

Abstract

A semiconductor device includes TFTs designed in accordance with characteristics of circuits. In a first structure of the invention, the TFT is formed by using a crystalline silicon film made of a unique crystal structure body. The crystal structure body has a structure in which rod-like or flattened rod-like crystals grow in a direction parallel to each other. In a second structure of the invention, growth distances of lateral growth regions are made different from each other in accordance with channel lengths of the TFTs. By this, characteristics of TFTs formed in one lateral growth region can be made as uniform as possible.

Description

A kind of portable data assistance and a kind of gamma camera

The application be the applying date be submit on January 20th, 1998, division day be that August 20, application number in 2004 are 200410064254.6, denomination of invention divides an application for the application for a patent for invention of " a kind of portable data assistance and a kind of gamma camera ".

Technical field

The present invention relates to a kind of semiconductor device, this semiconductor device is made of the on-chip thin-film transistor (TFT) that is formed at insulating surface.This semiconductor device comprises IC, LSI, electro-optical device or the like, and it is effective especially that the present invention is applied to electro-optical device.

Background technology

In recent years, (amorphous silicon film: a-Si) research of the semiconductor device of TFT formation has had progress to replaced amorphous silicon membrane by polysilicon membrane (polysilicon film: P-Si film) TFT.Particularly, because growing, semiconductor device is integrated in the R and D remarkable achievement of on-chip active matrix type displaying device for demand as the display device of PC monitor, video frequency camera and projecting apparatus etc.

About this active matrix type displaying device, known have a kind of US of being disclosed in patent 5250931 (people such as Misawa).Yet, need added value recently, SOP (system on the screen board) plan has been proposed, the wherein conventional logical circuit of realizing by the IC of exterior arrangement (signal processing circuit is display control circuit and computing circuit for example) is installed on the same substrate by TFT.

In addition, make progress for the research of making conventional IC or VLSI self by TFT.This is because TFT is formed on the insulating substrate, so that it has the minimum characteristics of parasitic capacitance, and we can say that TFT is more effective than the FET that is formed on the monocrystalline silicon when high speed operation.

Yet formation can realize the technology establishment as yet of the TFT of this plan.Reason is to use the polysilicon film of present employing when (comprise and be called high temperature polysilicon and low temperature polycrystalline silicon film), is difficult to obtain the TFT of enough performances, can't constitute the circuit that needs high-frequency drive.

Although can temporarily improve the operating rate of TFT by the size that reduces TFT, channel length (or gate length) reduce to have caused short-channel effect, so caused for example making shortcoming such as the withstand voltage reduction of drain electrode.So in utilizing the TFT of conventional silicon thin film, the proportion of utilization rule is very limited to the raising of operating rate, and from the very difficult operating rate that further improves of the angle of reliability.And there is following problem in silicon thin film, and promptly crystal grain and crystal boundary are irregular, causes irregular and crystal boundary affects the characteristic of TFT to a great extent.

Summary of the invention

The objective of the invention is to overcome the problems referred to above, a kind of semiconductor device that is made of the on-chip TFT that is formed at insulating surface is provided.Particularly, the purpose of this invention is to provide a kind of systematized electro-optical device (after this being called system display spare) on the logical circuit that constitutes by TFT and the function that has.

Incidentally, this semiconductor device comprises all devices that utilize the semiconductor function, and the product of all IGFET, TFT, IC, electro-optical device and application thereof all is included in the semiconductor device category on the broad sense.

According to a scheme of the present invention, a kind of portable data assistance that contains a display device is provided, described display device comprises and is included in same on-chip PEL (picture element) matrix circuit, drive circuit and logical circuit, PEL (picture element) matrix circuit wherein, drive circuit and logical circuit comprise a plurality of thin-film transistors, each thin-film transistor all has the active layer of crystal silicon film, subthreshold value coefficient with ten of 60-100mV/, and wherein required according to each circuit characteristic, the channel formation region that is included in a plurality of thin-film transistors in each circuit is made by each lateral growth region that the growth distance differs from one another.

The present invention also provides a kind of gamma camera that contains a display device, described display device is included in same on-chip PEL (picture element) matrix circuit, drive circuit and logical circuit, wherein said PEL (picture element) matrix circuit, drive circuit and logical circuit comprise a plurality of thin-film transistors, each thin-film transistor all has the active layer of crystal silicon film, subthreshold value coefficient with ten of 60-100mV/, and each of channel formation region at least that wherein is included in a plurality of thin-film transistors in each circuit is all made by a plurality of bar shaped crystal region, and on all borders in the inner adjacent crystal of a plurality of bar shaped crystal region district or basic all boundaries wherein, each atom in a plurality of crystal region is arranged continuously, do not form lattice defect, wherein " own substantially " even there are the silicon atom dangling bonds in expression, this part also can be offset by hydrogen or halogen, can not become lattice defect.

The present invention also provides a kind of gamma camera that contains a display device, described display device comprises and is included in same on-chip PEL (picture element) matrix circuit, drive circuit and logical circuit, wherein PEL (picture element) matrix circuit, drive circuit and logical circuit comprise a plurality of thin-film transistors, each thin-film transistor all has the active layer of crystal silicon film, subthreshold value coefficient with ten of 60-100mV/, and wherein required according to each circuit characteristic, the channel formation region that is included in a plurality of thin-film transistors in each circuit is made by each lateral growth region that the growth distance differs from one another.

In described portable data assistance or described gamma camera, some lateral growth region will become the channel formation region of the thin-film transistor that constitutes logical circuit and/or drive circuit, other lateral growth region will become the channel formation region of the thin-film transistor that constitutes the PEL (picture element) matrix circuit, and the former growth distance is less than the latter's growth distance.

The growth distance dependent of the channel length of wherein said a plurality of thin-film transistors and lateral growth region.

The present invention also provides a kind of gamma camera that contains a display device, described display device is included in same on-chip PEL (picture element) matrix circuit, drive circuit and logical circuit, wherein said PEL (picture element) matrix circuit, drive circuit and logical circuit comprise a plurality of thin-film transistors, each thin-film transistor all has the active layer of crystal silicon film, subthreshold value coefficient with ten of 60-100mV/, and each of channel formation region at least that wherein is included in a plurality of thin-film transistors in each circuit is all made by a plurality of bar shaped crystal region, and on all borders in the inner adjacent crystal of a plurality of bar shaped crystal region district or basic all boundaries wherein, each atom in a plurality of crystal region is arranged continuously, does not form lattice defect.

In described portable data assistance or described gamma camera, described crystal region comprises hydrogen or halogen, can not continuously arranged atom to offset boundary.

In described portable data assistance or described gamma camera, each of the channel formation region at least of described a plurality of thin-film transistors is all made by a plurality of bar shaped crystal region.

In described portable data assistance or described gamma camera, crystal silicon film is made of a kind of crystal structure body, has assembled a plurality of bar-shaped or flat rhabdolith of growth parallel to each other in the said crystal structure body.

In described portable data assistance or described gamma camera, in the bar-shaped or flat rhabdolith that constitutes crystal silicon film, lattice connects each other continuously, so that the inner monocrystalline that is used for charge carrier that is taken as.

In described portable data assistance or described gamma camera, the channel formation region of active layer is the district of intrinsic or is the district of intrinsic basically at least.

In described portable data assistance or described gamma camera, described active layer comprises one or more elements that are selected among Ni, Co, Fe, Sn, Pb, Pd, Pt, Cu, the Au, as catalytic elements, to impel the crystallization of silicon fiml, the concentration of described catalytic elements is not more than 1 * 10 ¹⁷Atom/cm ³

In described portable data assistance or described gamma camera, described active layer comprises one or more elements that are selected among Cl, F and the Br, and the concentration of these elements is 1 * 10 ¹⁵-1 * 10 ²⁰Atom/cm ³

In described portable data assistance or described gamma camera, constitute one or more elements among Cl, F and the Br of being selected from that the active layer of each thin-film transistor in described a plurality of thin-film transistor and the interface between the gate insulating film comprise high concentration.

In described portable data assistance or described gamma camera, in a plurality of thin-film transistors, the channel length of thin-film transistor that formation need be not less than the circuit of 0.1GHz driving frequency is 0.25-0.7 μ m, and the channel length that constitutes the thin-film transistor of the circuit that needs operating voltage to surpass 10V is 2-20 μ m.

In described portable data assistance or described gamma camera, in a plurality of thin-film transistors, the channel length of thin-film transistor that formation need be not less than the drive circuit of 0.1GHz driving frequency is 0.25-0.7 μ m, and the channel length that constitutes the thin-film transistor of the PEL (picture element) matrix circuit that needs operating voltage to surpass 10V is 2-20 μ m.

In described portable data assistance or described gamma camera, described gamma camera is selected from the group of video frequency camera and static gamma camera composition.

Description of drawings

Fig. 1 is the top view of display systems display.

Fig. 2 is the diagrammatic sketch of explanation ion implantation step.

Fig. 3 is the diagrammatic sketch of explanation second structure of the present invention.

Fig. 4 A and 4B are the diagrammatic sketch of showing operational amplifier spare structure and circuit configuration.

Fig. 5 A-5E is a diagrammatic sketch of showing cmos circuit and pixel TFT manufacturing step.

Fig. 6 A-6E is a diagrammatic sketch of showing cmos circuit and pixel TFT manufacturing step.

Fig. 7 A-7D is a diagrammatic sketch of showing cmos circuit and pixel TFT manufacturing step.

Fig. 8 is the photo of the unique crystalline texture of explanation.

Fig. 9 is the diagrammatic sketch of explanation ring oscillator frequency characteristic.

Figure 10 is a photo of showing the output wave spectrum of ring oscillator.

Figure 11 is a photo of showing the output pulse of shift register.

Figure 12 shows the diagrammatic sketch that concerns between frequency and pulse duration.

Figure 13 illustrates the diagrammatic sketch of rule (the scaling law) in proportion.

The configuration of explanation pixel region and the diagrammatic sketch of structure among Figure 14 A and the 4B.

Figure 15 A and 15B are the diagrammatic sketch of showing the cmos circuit structure.

Figure 16 A-16E is a diagrammatic sketch of showing application product.

Figure 17 A-17D is the photo and the schematic diagram of the lattice situation of explanation crystal boundary.

Figure 18 A-18C is a diagrammatic sketch of showing the manufacture method of semiconductor device.

Figure 19 A-19C is a diagrammatic sketch of showing the manufacture method of semiconductor device.

Figure 20 A-20D is a diagrammatic sketch of showing the manufacture method of semiconductor device.

Figure 21 A-21C is a diagrammatic sketch of showing the manufacture method of semiconductor device.

Figure 22 A and 22B are the diagrammatic sketch of showing the manufacture method of semiconductor device.

Figure 23 is a diagrammatic sketch of showing the ion implantation step.

Figure 24 A-24C is a diagrammatic sketch of showing the manufacture method of semiconductor device.

Figure 25 is a diagrammatic sketch of showing the pixel region structure.

Figure 26 A and 26B are top view and the profiles of showing the semiconductor device that is applied to reflective type liquid crystal display device.

Embodiment

Embodiment 1

Fig. 1 is the block diagram as the system display of semiconductor device example of the present invention.Being constructed as follows of system display of the present invention, integrated PEL (picture element) matrix circuit 102, source line driving circuit 103, grid line drive circuit 104 and logical circuit 105 on substrate 101.Among this embodiment, as an example with active-matrix liquid crystal display device.

Incidentally, the circuit structure shown in this embodiment only is an example, and circuit structure of the present invention is not limited to this.Main points of the present invention are that logical circuit 105 is contained on the same substrate, comprise that the structure of various circuit such as PEL (picture element) matrix circuit 102, source line driving circuit 103, grid line drive circuit 104 and logical circuit 105 is determined according to the needs of circuit design.

Among Fig. 1, source line driving circuit 103 mainly is made of shift register, level shifter, buffer, latch cicuit etc.Grid line drive circuit 104 mainly is made of shift register, multiplexer, level shifter, buffer etc.The nature shift register can be by for example counter and decoder replacement of the circuit with said function.Although Fig. 1 shows the circuit structure of digital operation, if system display is designed to analog operation, then source line driving circuit 103 comprises sampling and holding circuit etc.

In the source line driving circuit 103 and each circuit in the grid line drive circuit 104 as basic circuit, constitute wherein N channel TFT and the combination complimentary to one another of P channel TFT by the negative circuit of CMOS structure.Nature, although can adopt the one pole circuit, from reducing the angle of electrical power consumed, suitable is static type or dynamic type CMOS structural circuit.

PEL (picture element) matrix circuit 102 is made of a plurality of pixel regions 110 of being arranged to matrix, by many source lines 106 that are connected to source line driving circuit 103 and 107 and many grid lines 108 and 109 that are connected to grid line drive circuit 104 surround.

Each of a plurality of pixel regions 110 all comprises pixel TFT111, liquid crystal cells 112 and additional capacitor 113.Although not shown, liquid crystal cells 112 is made of pixel capacitors, opposite electrode and liquid crystal between the two.

Logical circuit 105 is meant that carrying out image shows all required circuit of necessary signal processing, for example the processing of the starting impulse of driving source lines drive circuit 103 and grid line drive circuit 104, clock signal etc. makes PEL (picture element) matrix circuit 102 carry out the processing of visual video signal displayed.

In the embodiment shown in fig. 1, logical circuit 105 comprises the oscillator 118 (being used for horizontal sweep) of phase comparator 114, LPF (low pass filter) 115, VCO (voltage-controlled oscillator) 116, frequency divider 117, source line drive, the oscillator 119 (being used for vertical scanning) and the D/A converter (digital-to-analog converter) 120 of grid line driver.

The inventor thinks, by monolithic other unshowned logical circuit is installed, I/O interface, the amplifying circuit (differential amplifier used from the signal of image sensor or CCD transmission of input and output for example, operational amplifier, comparator etc.), A/D converter, storage memory of data (RAM, ROM etc.) and last auxiliary circuit, the system display that can realize having CPU (CPU) function.

Reference number 121 expressions are according to the input of the analog signal of digital tone signal, and the input of the bit signal of digital tone signal is selected in 122 expressions, the input of 123 expression horizontal sweep synchronizing signals, the input of 124 expression vertical scan synchronization signal.Nature is integrated on the substrate if produce the oscillating circuit of analog signal, bit signal and synchronizing signal, then no longer needs input.

Because this system display is to be made by the on-chip TFT that insulating surface is arranged, its advantage be that parasitic capacitance is littler than the conventional TFT that is manufactured on the monocrystalline silicon.This leaves nothing to be desired from the operating rate that improves TFT.And, owing to utilize the island semiconductor layer of silicon thin film to be used to constitute active layer, so, realize interelement isolation easily, the phosphorus that mixes active layer or the control of boron concentration are also become simple.

[first structure of the present invention]

In order to realize system display shown in Figure 1, must be with the crystal silicon film TFT of the unique crystal structures body of inventor's invention.The following describes the characteristics of this unique crystal structures body and by the characteristics of its TFT that constitutes.

[characteristics of this unique crystal structures body]

Fig. 8 is the TEM photo of the crystal silicon film of this unique crystal structures body, and its multiplication factor is 250000.As shown in Figure 8, the crystal silicon film of inventor's acquisition has following characteristics.

(1) lattice structure is that lattice connects on almost specific direction each other continuously.

(2) carefully bar-shaped (or column) crystal or thin flat bar-shaped crystal growth.

(3) the parallel to each other or growth in one direction substantially parallel of a plurality of bar-shaped or flat rhabdoliths.

Observe photo shown in Figure 8, the rhabdolith that can confirm the narrow width of for example about 0.15 μ m is extending from the lower left to top-right tilted direction, and the border of qualification (crystal boundary) is at the two ends of crystal Width (hacures seen in the photo etc. are because the different cause of crystal plane direction).In addition, can confirm, because a plurality of rhabdoliths are in direction growth parallel to each other substantially, so a plurality of crystal boundary also extends substantially parallel.Because these crystal boundaries become the energy barrier in charge carrier (electronics or hole), so charge carrier can only move in having the rhabdolith of polarity inevitably.

As following detailed description, owing in the atmosphere of halogen-containing element, heat-treating above under 700 ℃ the temperature, the degree of crystallinity of crystal structure body greatly improves, and has removed catalytic elements by gettering, so catalytic elements does not cause any problem.Like this, the lattice in the rhabdolith is inevitable to each other to link to each other continuously, and its inside becomes for charge carrier is real and is the district of monocrystalline.So, also have characteristics, promptly almost without any the impurity scattering that stops carrier moving.

When forming the active layer of TFT, consistent by the direction of motion that is designed so that charge carrier with the bearing of trend of crystal boundary, can greatly improve the mobility of charge carrier rate.This is because the motion of charge carrier is adjusted to a specific direction by crystal boundary, thus because the cause that the scattering that the collision between charge carrier causes significantly weakens.Similarly, when the crystal silicon film formation active layer that single crystalline texture body constitutes, we can say active layer anisotropy for the characteristic of charge carrier.

In addition, can provide the characteristics of single crystalline texture body, promptly lattice is to connect continuously to each other at the crystal boundary place of bar-shaped or flat rhabdolith.Be explained with reference to Figure 17 A-17D below.

Figure 17 A is HRTEM (high-resolution TEM) photo, displaying be the amplification crystal boundary of the bar-shaped or flat rhabdolith in the crystal silicon film that constitutes by single crystalline texture body.Crystalline substance with HRTEM analysis and observation crystal resembles.Crystalline substance resembles the inventor in the crystal boundary by observing, and has obtained following discovery.

Utilize the HRTEM photo shown in Figure 17 A, can confirm, locate at the visible from top to bottom crystal boundary in the centre of photo (grain boundary), the adjacent bonds crystalline region suitably and continuously connects each other.Figure 17 B has schematically showed structure shown in Figure 17 A simplifiedly.Shown in Figure 17 B, although having that the crystalline substance of different directions resembles at crystal boundary is consistent to each other, this figure means because to constitute the atom of different crystal regions corresponding each other at the crystal boundary place, so form as the strong lattice defects such as (dangling bonds) of pairing.

Bar-shaped or flat rhabdolith constitutes crystal silicon film by many groups, forms structure as shown in figure 17 inevitably in all or basic all grain boundaries.Here, there are the silicon atom dangling bonds in " owning substantially " even a speech is meant, this part also can be offset (termination) by hydrogen or halogen, so this part can not become lattice defect.

On the other hand, as a reference, the TRTEM photo of the crystal silicon film that constitutes by another crystal structure body shown in Figure 17 C (this film is called high temperature polysilicon).Figure 17 D is its schematic diagram.In Figure 17 C, can confirm, the visible crystal boundary in photo center place, the crystalline substance of left side crystal region resembles with the right side crystal region is unordered and is connected.That is, shown in Figure 17 D, because atom is not corresponding each other, the residue key exists as dangling bonds 1701 and 1702.So there are many carrier traps at the crystal boundary place.

As mentioned above, the syndeton of the crystal silicon film that is made of unique crystal structures body of the present invention is very different with conventional crystal silicon film, although the characteristics of this silicon fiml are to have crystal boundary, they can not become the complex centre of charge carrier.

(utilizing the characteristics of the TFT of unique crystal structures body)

Measure the electrical characteristics of the TFT with the crystal silicon film active layer that constitutes by above-mentioned crystal structure body with the transistor characteristic measurement mechanism that can buy (Hewlett Packard makes: model is 4145B).So obtain following result.

(1) the subthreshold value coefficient is the parameter of the switch performance (moment that on/off operation changes) of displaying TFT, and is all little of ten of 60-100mV/ (being generally ten of 60-85mV/) for N type TFT and P type TFT.This numerical value is the isolated-gate field effect transistor (IGFET) of monocrystalline silicon system (IGFET) no better than.

(2) field-effect mobility (μ FE) is the parameter of expression TFT operating rate, and for N type TFT, it is greatly to 200-650cm ²/ Vs (is generally 250-300cm ²/ Vs), for P type TFT, it is 100-300cm ²/ Vs (is generally 150-200cm ²/ Vs).The operating rate that this means TFT of the present invention is bigger three times than conventional TFT.

(3) threshold voltage (V _Th) be the parameter of expression TFT driving voltage standard, for N type TFT, it is little of-0.5-1.5V, for P type TFT, is-1.5-0.5V.This means that TFT of the present invention can be by little source driven, so electrical power consumed can be very little.

As mentioned above, the TFT of above-mentioned crystal structure body formation has splendid switching characteristic and high operating rate characteristic.In addition, because this unique crystal structures body, this TFT has the advantages that to be subjected to short-channel effects hardly.These characteristics will be in following explanation.

Usually, reduced size of devices in the IC field, circuit of having realized and integrated and raising part characteristic according to rule (the scaling law) in proportion.Yet in the sub-micron district of channel length (distance of carrier moving direction in the channel formation region) less than 1 μ m, the short-channel effect apparition is so the raising of element characteristic reaches capacity.The concrete condition of short-channel effect can be referring to " PHYSICSOF VLSI DEVICE; People such as Mitsumasa Koyanai; Maruzen; 1986 ".

For example, when short-channel effect takes place, the withstand voltage reduction that drains, element is degenerated and is become obvious.So, proposed to suppress short-channel effect with methods such as for example channel doping methods.The impurity that evenly mixes channel formation region can hinder the motion of charge carrier, reduces transistorized operating rate but in this case.

On the other hand, can confirm, even that when raceway groove is as short as 0.6 μ m the TFT that the unique crystal structures system becomes also has high operating rate, it is withstand voltage to have high drain electrode simultaneously, estimates by accelerated tests, and this TFT is high reliability TFT.

The inventor infers, and by the TFT that the unique crystal structures system becomes, because the useful effect of crystal boundary, it drains withstand voltage higher.Promptly, in channel formation region, suppressed the expansion of depletion layer effectively by being basically parallel to the energy barrier that crystal boundary that orientation (be defined as charge carrier from the source to the direction of motion of leaking) extends produces, and suppressed owing to puncture the withstand voltage reduction of drain electrode from the drain region.

Promptly, can imagine, even in utilizing the TFT of conventional silicon thin film under the situation that influences apparition of short-channel effect, the unique crystal structures body also can suppress the expansion of depletion layer promptly even in sub-micron (0.01-2 μ m) district, thereby can suppress short-channel effect effectively.

In addition, as mentioned above, owing to also can suppress short-channel effect without manual method (channel doping method etc.), so can utilize the semiconductor film of the basic intrinsic of intrinsic-OR to make channel formation region.This is the greatest factor that improves the TFT operating rate.

Incidentally, this district is an intrinsic for intrinsic-OR substantially, and the meaning is one of to meet the following conditions at least.

(1) activation energy of silicon fiml is about 1/2 (Fermi level is positioned at the central authorities in forbidden band at least).

(2) impurity concentration in this district is lower than spin density (spin density).

(3) be the district or the intrinsic region of the non-doping of not having a mind to mix impurity.

In addition, as mentioned above, because crystal boundary has effectively suppressed depletion layer in the expansion of leaking side, so depletion-layer capacitance reduces greatly.Here, above-mentioned subthreshold value coefficient S is expressed from the next.

S≡ln10·KT/q[1+(Cd+Cit)/Cox]

Here, K is a Boltzmann constant, and T is an absolute temperature, and q is a quantities of charge, and Cd is a depletion-layer capacitance, and Cit is the equivalent capacity of interfacial state, and Cox is a gate oxidation films electric capacity.

Can imagine that the subthreshold value coefficient fact minimum as mentioned above and that interfacial state is minimum (reason will illustrate in an embodiment) of the TFT that is become by the unique crystal structures system has been supported the correctness about the little above-mentioned deduction of depletion capacitance Cd.

Below only be the crystal silicon film that contact is become by the actual unique crystal structures system that obtains of the inventor, with the electrical characteristics of the TFT that makes with this actual experiment, the inference of gained.Yet experimental data is real, and it also is genuine that TFT of the present invention has the excellent properties that very is different from the TFT of conventional silicon thin film system.

(characteristics of the circuit that constitutes by above-mentioned TFT)

Utilization is made ring oscillator by the TFT of the invention described above people's unique crystal structures system one-tenth, the following describes the frequency characteristic of this oscillator.Ring oscillator is a kind of circuit, and wherein each all connects into annular by the odd level negative circuit that the CMOS structure constitutes, and is used to realize the time-delay of one-level negative circuit.Experiment is as follows with the structure of ring oscillator.

Progression: nine grades

The thick gate insulating film of TFT: 30nm and 50nm

The grid of TFT are long: 0.6 μ m

Fig. 9 has showed the measurement result of the frequency of oscillation of ring oscillator when supply voltage that wave spectrum analyzer records is 5V.Among Fig. 9, trunnion axis is represented supply voltage (V _DD), vertical axis is represented frequency of oscillation (f _Osc).As shown in Figure 9, when using the gate insulation thickness, realized that frequency of oscillation is not less than 1Ghz as the TFT of 30nm.

The output wave spectrum situation of wave spectrum analyzer when Figure 10 has showed the frequency of oscillation that obtains 1.04GHz.Trunnion axis is represented frequency from 1GHz to 1.1GHz, and vertical axis is represented logarithm voltage (output amplitude).As can be seen from Figure 10, when 1.04Ghz, there is a peak value in the output wave spectrum.Incidentally, because the cause of this device resolution, the output wave spectrum has a hangover, does not influence experimental result.

In addition, the actual shift register of making one of TEG as the LSI circuit, the output pulse when determining to drive shift register under the driving frequency of 10-100MHz detects the service behaviour of shift register thus.Oscillographic screen shown in Figure 11 (top shows clock pulse, and the bottom shows the output pulse) has represented that the gate insulation thickness is that 30nm is thick, grid length is 0.6 μ m, operating frequency is that 100MHz, voltage voltage are that 5V and progression are the output pulse of 50 o'clock shift registers.

The result who obtains about the inventor, as shown in figure 12, the inverse (vertical axis) of output pulse width " t " is directly proportional with operating frequency (trunnion axis), confirmed that shift register has fabulous performance, so actual can be by the high-frequency drive that self realizes 100MHz, and can obtain having slightly the output pulse of distortion than ideal situation.Incidentally, owing in circuit structure, used two kinds of different shift registers in the experiment, so each shift register is called shift register 1 and 2.

The astonishing data of above-mentioned ring oscillator and shift register show, the performance of the TFT that is become by the unique crystal structures system can be compared with the IGFET that is made by monocrystalline silicon, or compares better.

Following data are supported above judgement.Figure 13 is a curve chart, and trunnion axis is supply voltage (V _DD), vertical axis is represented the time-delay (τ of the inverter of one-level F/O=1 _Pd) (the fan-out ratio is 1) (innovation of logic LSI technology, people such as Kenji Maeguchi, the 108th page, Science Forum company, 1995).Data when each curve (being represented by chain-dotted line) expression is made monocrystalline silicon FET according to the different designs rule among the figure have been showed so-called golden rule.

When the time-delay of the inverter that utilizes above-mentioned ring oscillator to obtain and the relational application between supply voltage are in this figure, obtain the curve shown in the solid line among Figure 13.It should be noted that with channel length to be that 0.6 μ m and thick gate insulating film are the inverter of the TFT manufacturing of 30nm, it is 0.5 μ m and thick gate insulating film (t that its performance is better than with channel length _Ox) be the inverter of the IGFET manufacturing of 11nm

Obviously, this performance that shows the TFT that is become by unique crystal structures system of the present invention is better than IGFET.For example, even it is bigger three times than IGFET to constitute the thickness of gate insulating film of above-mentioned TFT, can compare or be better than its TFT with IGFET but still can obtain performance.That is, the dielectric strength of the TFT of unique crystal structures system one-tenth is better than general IGFET.

Simultaneously, even reduce the TFT that the unique crystal structures system becomes, also can realize higher performance according to golden rule.This may be that TFT is subjected to the influence of short-channel effect hardly because of the cause owing to the unique crystal structures body.For example, if make ring oscillator shown in Figure 13, then wish to realize the operating frequency (because operating frequency " f " is the inverse of channel length square) of 9GHz according to golden rule by the rule of 0.2 μ m.

In addition, in low-pressure side, the slope (inclination) of the curve shown in the solid line (utilizing the inverter of first example structure) is milder than the curve shown in the chain-dotted line (inverter that normal IGFET makes), so we can say, the characteristic of its low-pressure side of inverter of the present invention is good especially.

As mentioned above, the TFT that is become by unique crystal structures system of the present invention has fabulous characteristic, and the circuit that is made of this TFT is a kind of very new components and parts that can realize greater than the high operation speed of 10GHz.By obtaining above-mentioned TFT, at first can realize comprising the system display of logical circuit.

[second kind of structure of the present invention]

The inventor has invented the integrated level that improves system display, the device that reduces the characteristic inconsistency of TFT.Below structure of the present invention will be described.

(mixing the method for catalytic elements)

In amorphous silicon film, mix the metallic element that impels crystallization, form the crystal silicon film that becomes by above-mentioned unique crystal structures system thus.The inventor openly puts down in 8-78329 in the Japanese unexamined special permission and discloses a kind of technology that amorphous silicon film is transformed into crystal silicon film.By disclosed this technology, optionally mix the catalytic elements (nickel, cobalt etc.) of impelling crystallization to amorphous silicon film, amorphous silicon film is from being arranged essentially parallel to the starting point crystallization of mixing part of substrate surface, and has only transversely crystal region (after this being called lateral growth region) as the active layer of TFT.

Above-mentioned unique crystal structures body (structure that is made of one group of bar-shaped or flat rhabdolith) is that the crystal habit of this lateral growth region causes.So, we can say that lateral growth region is one group of bar-shaped or flat rhabdolith or one group of a plurality of crystal region of arranging by bar shaped.

Yet, when attempting to realize system display shown in Figure 1, if similarly with being disclosed in technology in this document, because catalytic elements is mixed the restriction apparition aspect circuit design due to the district.For example, in this document,, need make at least 20 μ m so mix sector width because solution is spin coating.Owing to wherein exist the catalytic elements of high concentration, can not be used as active layer so mix the district.So mixing the district takes up space and becomes dead band in the circuit design.

And, because it is limited that (1) mixes sector width, (2) catalytic elements of same concentrations is incorporated into and mixes the district, all has identical growth distance so be formed at same on-chip all lateral growth region, and formed the lateral growth region of about 50-150 μ m under 600 ℃ thermal crystalline.That is, in district, in a lateral growth region, can form a plurality of TFT with fine circuitry structure.

This becomes the biggest obstacle that realizes display shown in Figure 1.The TFT characteristic that hope need be made TFT with high operation speed and Analog signals is consistent as much as possible.Yet, because even the diverse location degree of crystallinity in same lateral growth region also slightly different, so when forming a plurality of TFT in a lateral growth region, the characteristic of TFT can be different because of the difference of position.

Therefore, the inventor proposes to utilize ion implantation (ion is injected method) to mix catalytic elements, the method for the problem of apparition when realizing system display of the present invention as solution.Here, utilize ion implantation to mix method and its advantage of catalytic elements with reference to Fig. 2 explanation below.

Among Fig. 2, reference number 201 is substrate (comprising glass substrate or quartz substrate), and 202 is the counterdie of being made by silicon oxide film, and 203 is amorphous silicon film, and 204 for becoming the silicon oxide film of resilient coating.Reference number 205 is expression photoresist mask, and has only removed the zone that will mix catalytic elements.About exposure, preferably utilize exposure methods such as the exposure method of excimer laser and electron beam to the photoresist mask.

Because these exposure methods can form imperceptible figure, mix the district so can form the catalytic elements of (the being generally 0.1-0.35 μ m) slit width (slit width) that has 0.01-1.0 μ m.If the photoresist figure is directly formed by electron beam etc., the freedom shape of then mixing the catalytic elements district very increases.

Shown in Fig. 2 left part, mix ion in the following manner, make the peak value of ion distribution 207 be positioned at amorphous silicon film 203.Like this, just, can in amorphous silicon film 203, form and mix predetermined concentration (preferably 3 * 10 ¹⁹-1.5 * 10 ²¹Atom/cm ³) the district 206 of catalytic elements.

Except that the ion implantation of carrying out mass separation, can mix ion by the plasma doping method (ion doping etc.) of not carrying out mass separation.Yet, owing to only can mix catalytic elements, so ion implantation is better.

In addition, structure as shown in Figure 2, resilient coating 204 covers amorphous silicon films 203, and only with those catalytic elements of having passed resilient coating 204.Such advantage is that the damage that the collision of ion causes when injecting because of ion can directly not arrive amorphous silicon film 203.

In addition, owing to only use near the value of ion distribution 207 peak values,, and has good duplication of production so by making the ion implanting conditions optimization, the incorporation that can control catalytic elements is controlled.That is, because the growth of lateral growth region distance changes with the concentration of mixing catalytic elements, so utilize ion implantation can easily control lateral growth distance.

This means that the lateral growth region with required size can be formed at desired location.That is, consider the size of TFT, can form the lateral growth region (length of channel formation region) of essential and sufficient size.

(outline of second structure)

According to said method, as shown in Figure 3, can on same substrate, form the different lateral growth region of growth distance.Among Fig. 3 A, the schematic diagram of the system display that 301 expressions are shown in Figure 1,302 expression PEL (picture element) matrix circuit, 303 and 304 expression drive circuits, 305 presentation logic circuit.

Need high voltage endurance owing to constitute the TFT (pixel TFT) of PEL (picture element) matrix circuit 302, so the method that channel length (grid are long) is prolonged.Like this, shown in reference number 306, the growth that is designed so that lateral growth region at this moment, after testing the relation that obtains to mix between concentration and increment, can regulate being incorporated into the concentration n that mixes the catalytic elements in the district 308 apart from the length of being longer than active area 307 ₁

On the other hand, need the high speed operation characteristic, so make the method for channel length short (0.25-0.7 μ m) owing to constitute the TFT (logic TFT) of logical circuit 305.So, shown in reference number 309, the growth distance X 2 of lateral growth region can be according to the length adjustment of logic TFT active layer 310.At this moment, mixing the concentration of distinguishing catalysis in 311 is n ₂

As mentioned above, under situation shown in Figure 3, the lateral growth region with different growth distance X 1 and X2 is present on the same substrate.At this moment, X1〉X2.Lateral growth region with growth distance X 1 and X2 is by variable concentrations n ₁And n ₂Mix district growth.At this moment, n ₁N ₂That is, the concentration that catalytic elements in the district is mixed in this structure utilization is high more, then the long more phenomenon of the growth of lateral growth region distance.

In this way, even it is identical to mix district's shape, can form lateral growth region with required width by the concentration of regulating catalytic elements.That is, when the main points of the present invention's second structure were that channel length changes according to the circuit desirable characteristics, formation had the lateral growth region that different growth distances are arranged according to channel length.

Growth distance is according to the difference of channel length and difference, and the growth of channel length and lateral growth region apart between certain relation is arranged.For example, can imagine, regulate the concentration of catalytic elements, make the channel length distance of fixed size become the growth distance with several microns, so that channel formation region is included in the lateral growth region fully, or regulate the concentration of catalytic elements, make the distance that doubles channel length become the growth distance.Although we can not unconditionally say because of the growth range error or when forming active layer the accuracy of composition can change this relation, mix for what determine catalytic elements that this relation is important the concentration.

The advantage of the present invention's second structure is, lateral growth region particularly will be made the district of fine TFT therein needn't be big excessively.

For example, when the active layer that forms by the logic TFT of 309 expressions, if the width of lateral growth region is excessive, then lateral growth region extends to the circuit with difference in functionality, then can cause aforesaid TFT characteristic inconsistent.Therefore,, or comprise that the circuit that needs TFT characteristic uniform structure especially for example during differential amplifier exclusive disjunction amplifier, can produce harmful effect then at the circuit that constitutes by high frequency drives if caused the TFT characteristic inconsistent.

Illustrate that with reference to Fig. 4 A and 4B second structure applications of the present invention is in the example of operational amplifier as the logical circuit example below.Fig. 4 A shows the example of the operational amplifier that is made of eight TFT Tr1-Tr8, and Fig. 4 B is the circuit diagram of this operational amplifier.

Among Fig. 4 A, the active layer that 401 expressions are made of above-mentioned unique crystal structures body, and constitute TFTTr1-Tr8.Reference number 402 expression first wiring layer is as the lead-out wire of the gate insulating film of TFT or be used for output (in the figure, have the institute of identical figure leaded in same wiring layer).Reference number 403 expressions second wiring layer is used to connect TFT and input, power end (V _DDEnd), GND end and offset side.The district of catalytic elements has been mixed in reference number 404-407 expressions by ion implantation.

At this moment, the operational amplifier shown in Fig. 4 A (or Fig. 4 B) is made of differential amplifier circuit, as a unit that is made of TFT Tr4 and Tr8 (or Tr6 and Tr7).The characteristics of differential amplifier circuit are, even temperature or voltage change, owing to this variation acts on two TFT simultaneously, so export unaffected.Yet for realizing this characteristics, primary is the consistency of two TFT characteristics.

, reach a conclusion for this reason, mix district 405, mix district 407, mix the district from each catalytic elements so that the active layer of formation TFT Tr4 and Tr8 is arranged on identical distance for TFT Tr8 is provided with for TFT Tr4 is provided with.Also the active layer that constitutes TFT Tr6 and Tr7 is similarly measured.

Because the logical circuit that is made of TFT needs high operation speed, grid are long wants little of about 025-0.7 μ m.So, the size of operation amplifier circuit shown in Fig. 4 A is about 5-20 μ m.

Yet, according to openly flat 8-78329 disclosed technology of Japanese unexamined special permission,, catalytic elements is at least 20 μ m because mixing the width in district, mix the district so can't between two TFT, form.And, owing to lateral growth region becomes greater than its necessary value, so can not obtain making TFT characteristic consistent method.That is, can realize structure shown in Fig. 4 A by the present invention's second structure.

When the fine circuitry shown in Fig. 4 A, too big if lateral growth region becomes, then its influence will feed through to adjacent lateral growth region, and will be bad like this.With second structure of the present invention,, can easily control the growth distance of lateral growth region by regulating the concentration of catalytic elements.So, even, also the influence each other in cross growth interval can be suppressed to minimum mixing the district when meticulous arrangement architecture is arranged.

Nature when the pixel TFT that constitutes the PEL (picture element) matrix circuit is long, can prolong the growth distance in grid length by the incorporation that increases catalytic elements.Under TFT characteristic consistency fine circuitry situation out of question, can also constitute a plurality of active layers simultaneously by the degree of depth that increases catalytic elements, to form wide lateral growth region.

[second embodiment 1

In the system shown in Figure 1 display of embodiment 1, the elementary cell that constitutes the circuit of logical circuit 105, drive circuit 103 and 104 is the cmos circuit (negative circuit) of N channel TFT and P channel TFT complementary combinations.Because these drive circuits need 0.1-2GHz to surpass the high driving frequency of 2GHz sometimes sometimes, grid are long little of 0.25-0.7 μ m.

On the other hand, because PEL (picture element) matrix circuit 102 needs to bear high voltage above 10V in liquid crystal display device, be about 2-20 μ m so grid are long.In some cases, utilize actual multiple-grid TFT for series connection TFT.

In this embodiment, showed that the TFT that has a different components size according to the circuit desirable characteristics is formed at same on-chip embodiment, be formed with the lateral growth region of different growth distances, the TFT that utilizes this district manufacturing to constitute according to each device size by single crystal.Illustrate the step of on same substrate, making cmos circuit and pixel TFT below with reference to Fig. 5-7.

Among Fig. 5 A, 501 expression quartz substrates.But can replace quartz substrate with the ceramic substrate that the thick dielectric film of 0.5-5 μ m is arranged on its surface, silicon single crystal wafer or polycrystalline silicon wafer.Here, about silicon wafer, just enough with low grade wafer used in the solar cell, this is more cheap than quartz substrate.Like this, in that be used for need be with under the situation of transparent substrate, as reflection type display device or IC chip, available silicon wafer.

Reference number 502 expression amorphous silicon films are regulated its thickness, and (considered after the thermal oxidation thickness reduce) becomes 10-75nm (preferably 15-45nm) so that final thickness.The formation of film can be used low pressure hot CVD method or plasma CVD method.Reference number 503 expression thin oxide films, its thick 5-50nm that is about is obtained by oxidation amorphous silicon film 502.

Then, form selection catalysis and mix the photoresist mask 504 in district.The contact hole that wide 0.01-1 μ m is arranged on the photoresist mask 504, as shown in Figure 2.Contact hole is used for lateral growth region, and this district will become the active area of the TFT that constitutes the CMOD circuit subsequently.

Mix the catalytic elements nickel (Ni) that impels the amorphous silicon film crystallization with ion implantation.Can use cobalt (Co), iron (Fe), tin (Sn), plumbous (Pb), palladium (Pd), platinum (Pt), copper (Cu), gold (Au) etc. to replace nickel as for catalytic elements.

At this moment, being incorporated into the nickel concentration that mixes in the district 505 is n ₁, be the lateral growth region of X1 to form the growth distance.Since the condition difference of thermal crystalline subsequently, n ₁Value dissimilate, so this value is tested definite (Fig. 5 A) by the operator.

Then, remove photoresist mask 504, form photoresist mask 506 then again.This photoresist mask 506 is used to form the lateral growth region that will become the active area of pixel TFT subsequently.Mix nickel with ion implantation again then.At this moment, being incorporated into the nickel concentration that mixes district 507 is n ₂, forming the growth distance thus is the lateral growth region of X2.This n ₂Value also can be tested definite (Fig. 5 B) by the operator with above similar.

As mentioned above, at least a portion has been mixed and has respectively been mixed the mutually different catalytic elements of district's concentration on the same substrate.

Then, finish to mix the step of catalytic elements, under 500-700 ℃ of temperature, be generally under 550 ℃-650 ℃ the temperature, in the atmosphere that contains inert gas or hydrogen, heat-treat, the time is 4-8 hours, thereby makes the amorphous silicon film crystallization.Nickel (or nickle silicide) when crystallization is carried out in the film becomes nuclearing centre (Fig. 5 C).

The crystallization of amorphous silicon film 502 at first distinguishes 505 and 507 from having mixed mixing of nickel, forms the lateral growth region 508 and 509 that is basically parallel to substrate 501 thus.As mentioned above, the nickel concentration that mixes in the district 505 and 507 is respectively n ₁And n ₂, the relation between lateral growth region 508 (growth distance X 1) and 509 (growth distance X 2) satisfies X1〉and X2.That is, in the same at least on-chip part, formed the growth distance lateral growth region different with other lateral growth region.

By the present invention, has only lateral growth region 508 and 509 as crystal silicon film.That is, because mixing the setting in district, the position that lateral growth region forms basis optionally designs, so opposite with conventional polysilicon film, crystal boundary can not influence the characteristic of TFT.

After carrying out the heat treatment end of crystallization, carry out composition, form the island semiconductor layer (active layer) 510-512 that only constitutes by lateral growth region.Here reference number 510 expressions constitute the active layer of the N channel TFT of cmos circuit, and 511 expressions constitute the active layer of the P channel TFT of cmos circuit, and 512 expressions constitute the active layer (Fig. 5 D) of the N channel TFT of pixel TFT.

Even under the situation shown in Fig. 5 D, still remain with some expression lateral growth region 508 and 509 vestiges that exist.For example, silicide is preferentially disappeared, in the bottom under the part of just mixing district's existence (this moment is for quartzy), formed groove owing to mix district 505 main 507.In addition, because fractional condensation takes place in catalytic elements in the end of lateral growth region (end points of crystallization), so formed groove at the bottom in this district.In addition, the concentration that catalytic elements is mixed in the district 505 and 507 is different owing to mixing, so can imagine, degree of crystallinity bar-shaped or flat rhabdolith is different with mixing concentration with shape.

After having formed the film formed active layer 510-512 of the silicon metal that constitutes by lateral growth region, the gate insulating film 513 that the growing silicon oxide film constitutes on active layer 510-512.At this moment, wish that the thickness of MOCS circuit side (by 514 expressions) gate insulating film 513 is different from the thickness of pixel TFT side (by 515 expressions).

Because in cmos circuit, formed the long TFT of short grid that is used for high-frequency drive, thus from the withstand voltage angle of low drain electrode with, only need operating voltage lower.Like this, preferably the thickness of gate insulating film less than 80nm (being generally 50nm), can reduce threshold voltage and operating voltage more than or equal to 2nm thus.On the other hand, because pixel TFT has high working voltage, so be to be not less than 80nm by the thickness that makes gate insulating film to be not more than the withstand voltage method of 250nm (being generally 120nm) derivation raising drain electrode effectively.

In order on same substrate, to be formed with the gate insulating film of different thickness, can be with for example utilizing mask to selectively form the method for lamination, or utilize as selective oxidation methods such as LOCOS methods, on specific active layer, form heat oxide film, thereby make film thicker.When being not more than 50nm, the heat oxide film that can only obtain with a kind of step of thermal oxidation in back is as dielectric film at the final thickness of gate insulating film.

Then, shown in Fig. 5 E, heat-treat, remove this heat treatment of catalytic elements (nickel) by gettering (gettering process) and utilized the gettering effect of halogen metallic element.In order to realize the gettering effect, preferably carry out the above-mentioned heat treatment that temperature surpasses 700 ℃ by halogen.Like this, in this embodiment, the temperature surpassing 700 ℃ is preferably in 800-1000 ℃ (being generally 950 ℃), heat-treats, and the processing time is 0.1-6 hour, is generally 0.5-1 hour.

Here, the heat treated temperature of the example of displaying is 950 ℃, and the time is 30 minutes, at the oxygen (O of the hydrogen chloride that contains 0.5-10vol% (this example is 3vol%) ₂) carry out in the atmosphere.When the concentration of HCL is higher than above-mentioned concentration, produce membrane thickness unevenness on the surface of active layer 209, so not preferred higher concentration.

Nitrogen (N with high concentration ₂) sneak into above-mentioned oxidizing atmosphere formation atmosphere, can reduce the oxidation rate of crystal silicon film.This is an effective method for increasing the gettering time but not prolonging the required time of thermal oxidative reaction.

Although make halogen-containing compound with HCl gas, replace HCl gas, can be with being selected from HF, NF ₃, HBr, Cl ₂, ClF ₃, BCl ₃, F ₂, Br ₂Deng in one or more materials.

Can imagine that in this step, the nickel that is incorporated in lateral growth region 508 and 509 is sucked away, and becomes the volatility nickel chloride, escapes in the air, thereby has removed nickel under the effect of chlorine.Incidentally, owing to form heat oxide film all as thin as a wafer in oxide-film 503 on the silicon fiml and the gettering process, they can not become the barrier layer that hinders nickel chloride to escape.

So, by the gettering process of catalytic elements, the nickel concentration in the lateral growth region 508 and 509 is reduced to 1 * 10 ¹⁷Individual atom/cm ³Or littler (it is following preferably to arrive spin density).Incidentally, the impurity degree of depth is defined as the minimum measured value that sims analysis obtains among the present invention.By similar sims analysis, can confirm that concentration is 1 * 10 ¹⁵-1 * 10 ²⁰Individual atom/cm ³The halogen residue that is used for gettering process is in lateral growth region 508 and 509.

By above-mentioned heat treatment, thermal oxidative reaction takes place in 513 interfaces of active layer 510-512 and gate insulating film, and the gross thickness of gate insulating film 513 increases because of formed heat oxide film (not shown).Make that thus active layer 510-512 is thinner, proportional with heat oxide film.When the attenuation of active layer thickness, promoted reducing or effect such as field-effect mobility raising of TFT cut-off current for example.At this moment, can confirm that the halogen of above-mentioned high concentration is distributed between the heat oxide film of active layer 510-512 and heat treatment formation by sims analysis.Heat treatment in halogen atmosphere in blanket of nitrogen, is carried out heat treatment in about 1 hour after finishing under 950 ℃ temperature, thereby improves the quality of gate insulating film 513, simultaneously, can obtain splendid semiconductor and interfacial insulating film.

The crystal silicon film that forms by above-mentioned steps is made of single crystalline texture body as be shown in the examples.Promptly become and to obtain the splendid TFT of electrical characteristics shown in embodiment 1.

Then, form the aluminium film (not shown) of the scandium that contains 0.2wt%, and form the electrode pattern of the original shape that will become grid subsequently.The surface of this figure of anodic oxidation forms grid 516-518 and anode oxide film 519-521 (Fig. 6 A).

At this moment, the live width of grid 516-518 can be determined according to the required characteristic of circuit.For logical circuit that needs high-frequency drive etc., live width can be decided to be 0.25-0.7 μ m, and for pixel circuit of the high voltage endurance of needs etc., live width is decided to be 2-20 μ m.

Then, utilize grid 516-518 to make mask, corrode gate insulating film 513 in self aligned mode.Corrosion can be to utilize CHF ₃Dry etching.By this step, only under grid, leave gate insulating film 522-524.Then, form covering and will become the mask 525 in P channel TFT district, and mix the foreign ion that forms the N type.Mixing of foreign ion can be by ion implantation or plasma doping method.Because the concentration of this moment is (by n ^-Expression) will become (the concentration about 1 * 10 in LDD district subsequently ¹⁸-1 * 10 ¹⁹Atom/cm ³), so must obtain best empirical value in advance, and control this concentration in advance.Form n in this way ^-District 526-529 (Fig. 6 B).

n ^-After district 526-529 forms, remove photoresist mask 525, form the photoresist mask 530 that covers the N channel TFT then.Mix the foreign ion that forms the P type then, form p ^-District 531 and 532.Because p ^-The concentration in district 531 and 532 also becomes the concentration (about 5 * 10 in LDD district ¹⁸-5 * 10 ¹⁹Atom/cm ³), must control this concentration (Fig. 6 C) in advance.

In this way, form n ^-District 526-529 and p ^-Behind the district 531-532, remove photoresist mask 530.Forming thick then is the not shown silicon oxide film of 0.5-2 μ m, and forms sidewall 533-535 by the deep etch method.

Then, form the photoresist mask 536 that covers the P channel TFT again, and mix the foreign ion that forms the N type.The ion concentration of mixing is (by n ⁺Expression) is higher than above-mentioned concentration n ^-Regulate this concentration, make the sheet resistance in source/drain region become 500 Ω following (preferably 300 Ω are following).

Step thus forms the source region 537 and the drain region 538 of the N channel TFT that constitutes cmos circuit.Because district 539 is hidden by sidewall, so its concentration no longer changes, this district becomes low concentration impurity district (particularly this district of drain region side is called the LDD district).Just the district under grid becomes the channel formation region 540 of the basic intrinsic of intrinsic-OR.Simultaneously, formation will become active area 541, drain region 542, low concentration impurity district 543 and the channel formation region 544 (Fig. 6 E) of the N channel TFT of pixel TFT.

Then, remove photoresist mask 536, and form the photoresist mask 545 that covers the N channel TFT.Mix the foreign ion that forms the P type, concentration is (by P ⁺Expression) is higher than the concentration of mixing for the first time, so formed source region 546, drain region 547, low concentration impurity district 548 and the channel formation region 549 (Fig. 7 A) that constitutes the P channel TFT of cmos circuit.

All active layers have been formed in the above described manner.The step of mixing all foreign ions is removed photoresist mask 545 after finishing, and carries out for example heat treatments such as furnace annealing, laser annealing or lamp annealing then, thus the activator impurity ion.Incidentally, ion injection period can repair the damage that active layer causes this moment.

Then, form titanium (Ti) film 550 of thick 20-50nm, the portable lighter of going forward side by side annealing heat treatment.At this moment, the silicon fiml that contacts with titanium film 550 becomes silicide, so form titanium silicide film 551-553 in source/drain region.Can use tungsten (W), tantalum (Ta), molybdenum (Mo) etc. to replace titanium.

After forming silicide, composition titanium film 550 forms island figure 554-556 on source/drain region.Island figure 554-556 is used to prevent disappear when titanium silicide film 551-553 from forming the contact hole of connection source/drain region and wiring afterwards.Nature if titanium silicide is bigger to the selection rate of the interlayer dielectric that will form contact hole thereon, then can be save island figure 554-556.

Then, form the silicon oxide film of thick 0.3-1 μ m, as first interlayer dielectric 557.Form contact hole, source wiring 558-560 and leak routing 561 and 562 then.In this way, obtain state shown in Fig. 7 C.As for first interlayer dielectric 557, can adopt organic resin film.

Obtaining shown in Fig. 7 C behind the state second interlayer dielectric that forms thick 0.5-3 μ m and constitute by organic resin film.Can make organic resin film with polyimides, acrylic acid, polyamide, polyimide amide (polyimide amide) etc.Below enumerate the advantage as organic resin molding, (1) film formation method is simple, and (2) thickness is done thickly easily, and (3) relative dielectric constant is low, can reduce parasitic capacitance, (4) flatness excellence.

The black mask 564 that on the pixel TFT on the interlayer dielectric 563, forms thick 100nm and make by the film that light-proofness is arranged.In fact, black mask is arranged at the position that needs shading, for example in the wiring of PEL (picture element) matrix circuit or on the TFT.In this embodiment, although make black mask with titanium film, can be with the resin molding that contains black pigment.

After forming black mask 564, make the 3rd interlayer dielectric 565 with the organic resin film that forms thick 0.1-0.3 μ m.In the second and the 3rd interlayer dielectric 563 and 565, form contact hole then, form the pixel capacitors 566 (Fig. 7 D) of thick 120nm.

When the display device of manufacturing is the light-transmission type display device, can make pixel capacitors 566 with nesa coating (for example ITO film), when being reflection type display device, can make pixel capacitors 566 with reflective conductive film (as the aluminium film).

At this moment, in black mask 564 and pixel capacitors 566 overlapping areas, form additional capacitor.This additional capacitor is as storage capacitance, and the voltage that protection is added on the pixel capacitors is a steady state value.Like this, in this embodiment, make to constitute the insulator of additional capacitor with the 3rd dielectric film 565.If the 3rd dielectric film is made of relative dielectric constant higher silicon oxide film or silicon nitride film, then can increase the capacity of additional capacitor.

At last, in nitrogen atmosphere, heat whole substrate, the hydrogenation all elements is so that the dangling bonds (not pairing key) in the compensate film (particularly active area).By above-mentioned steps, can on same substrate, form cmos circuit and pixel TFT.

[embodiment 3]

In this embodiment, will the structure example that constitute the pixel region of PEL (picture element) matrix circuit in the system display shown in Figure 1 be described.14A is a top view of showing this pixel region.

In Figure 14 A, 1401 and 1402 expression active layers, 1403 and 1404 expression grid lines, 1405 and 1406 expression source lines.In fact, many roots line and grid line are perpendicular to one another arranged in a crossed manner, and a plurality of districts that surrounded by source line and grid line are arranged to matrix, as the pixel region 110 among Fig. 1.

Grid line 1404 is overlapped in three positions on the active layer 1402.That is, form and three grid TFT of the three pixel TFT same structures that are one another in series.

Grating routing 1404 and 1406 can be arranged in the layer that is lower than active layer 1401 and 1402, puts upside down irregular type TFT structure with formation.In this case, the most handy high heat proof material, for example polysilicon film as grid, so just can make the heat treatment of carrying out in the manufacturing silicon thin film step shown in the grid E of anti-Fig. 5.

The contact portion of reference number 1407 expression active layers 1402 (source region) and source line 1405, the contact portion of 1408 expression active layers 1402 (drain region) and leak routing 1409, the contact portion of 1410 expression leak routings 1409 and pixel capacitors 1411.

District 1412 shown in the oblique line is black masks, forms this mask in order that cover active layer 1401 and 1402, grating routing 1403 and 1404, source line 1405 and 1406.Black mask 1412 is overlapping with leak routing 1409 in district 1413, so form additional capacitor at black mask and 1409 of leak routings.

Pixel capacitors 1411 is arranged on the black mask 1412 by the 3rd interlayer dielectric.Pixel capacitors 1411 makes its marginal portion do not covered by black mask 1412 with slipping up when constituting, do not become the image displaying area that forms image with black mask 1412 overlapping areas 1414.In fact, relative substrate, comparative electrode and liquid crystal layer are arranged on the pixel capacitors 1411, to constitute liquid crystal cells 112, as shown in Figure 1.

Figure 14 B is the profile of being got along the line A-A ' among Figure 14 A.Because the base transistor structure is described at embodiment 2, so the corresponding part of following key diagram 14B and Figure 14 A.

Among Figure 14 B, 1415 expression quartz substrates, the source region and the drain region of the active layer 1402 among the 1416 and 1417 difference presentation graphs 14A.Reference number 1418 expressions are corresponding to the gate electrode of the grating routing among Figure 14 A 1404.Although three gate electrodes are arranged side by side among the figure, in fact they are made of the same wiring shown in Figure 14 A.

Source wiring 1420 (corresponding to 1405 among Figure 14 A) and leak routing 1421 (corresponding to 1409 among Figure 14 A) are arranged on first interlayer dielectric 1419.The source line of reference number 1422 expression adjacent source lines 1420.

Second interlayer dielectric 1423 that formation is made by silicon oxide film, silicon nitride film or its stacked film, its thickness is 50-200nm, to cover source wiring 1420 and leak routing 1421.Form the 3rd interlayer dielectric of making by organic resin 1424 thereon.In addition, black mask 1425 (corresponding to 1412 among Figure 14 A) is set on the 3rd interlayer dielectric 1424.

At this moment, before forming black mask 1425, remove the 3rd interlayer dielectric 1424 on the zone 1426.Like this, in zone 1426, formed the additional capacitor 1427 that the laminated construction by leak routing 1421, second interlayer dielectric 1423 and black mask 1425 forms.Additional capacitor 1427 is corresponding to additional capacitor 1411 among Figure 14 A.

If additional capacitor 1427 forms structure shown in Figure 14 B, because the capacity of this additional capacitor is by 1423 decisions of second interlayer dielectric, thus can be by with material with high relative dielectric constant, or increase this capacity by the attenuate thickness.Yet in order to form this additional capacitor, owing to must remove the 3rd interlayer dielectric 1424, second interlayer dielectric 1423 on the while reserve area 1426 is so must optionally corrode the second and the 3rd interlayer dielectric.In this case, about second interlayer dielectric 1423, be effective with the stacked film of silicon oxide film or silicon oxide film and silicon nitride film.

The 4th interlayer dielectric that reference number 1428 expressions are made by organic resin film, pixel capacitors 1429 is formed thereon, and at this moment, pixel capacitors 1429 is electrically connected with drain region 1417 by leak routing 1421.Like this, additional capacitor 1427 can be taken as the electric capacity that is series on the pixel capacitors 1429.

Substrate 1430 is the relative substrates that formed comparative electrode 1431 on it.Active matrix substrate 1415 is bonded on the relative substrate 1430, with the liquid crystal cells 112 among formation Fig. 1, thus clamping liquid crystal layer 1432.

[embodiment 4]

In this embodiment, constitute the embodiment of the different cmos circuit of structure and embodiment 2 with reference to Figure 15 A and 15B explanation.Because the basic structure of Figure 15 A and 15B is identical with the cmos circuit shown in the embodiment 2, so the identical reference number of suitable and embodiment 2.

Figure 15 A has showed an example, and wherein in the cmos circuit shown in the embodiment 2, cmos circuit constitutes by having gate electrode 1501 that the silicon thin film (polysilicon film) that utilizes given conduction type forms and 1502 Si-gate type TFT.This TFT can be double grid type TFT, wherein the conduction type of gate electrode according to the N channel TFT with the P channel TFT and different (N type or P types).

When forming this silicon gate structure, when forming titanium silicide film 551 and 552, form titanium silicide film 1503 and 1504 on the top of gate electrode 1501 and 1502.Like this, can make gate electrode with connecting wiring that gate electrode links to each other between ohmic contact better.

Figure 15 B has showed an example, wherein in the CMOS structure shown in the embodiment 2, does not form the sidewall 533 that is made of titanium and 534 and island figure 554 and 555.In this structure, low concentration impurity district 539 and 548 length are by the width decision of the end (extending to gate electrode 516 and 517 outer parts) of gate insulating film 1505 and 1506.And titanium silicide film 1507 directly contacts with 561 with source wiring 558,559 with 1508 in this structure.

Sidewall 533 among the embodiment 2 and 534 main effect are the length and the doping contents of decision low concentration impurity district 539 and 548.Yet, shown in Figure 15 B in the structure, owing to adopted openly flat 7-135318 disclosed technology of Japanese unexamined special permission, so can form this structure without sidewall.

Island figure 554 among the embodiment 2 and 555 main effect are to guarantee titanium silicide film 551 in the source of being formed at/drain region and the source/leak routing and 552 ohmic contact.In this case, island figure 554 and 555 also plays protection titanium silicide film 551 and 552 effect, and these films are removed when preventing to form contact hole in interlayer dielectric 557.

In this embodiment, form contact hole by the dry etching method, interlayer dielectric 557 and titanium silicide film 551 and 552 s' selection rate improves, and does not need island figure 554 and 555 to make protective layer so form this structure.

Simplify to form sidewall 533 and 544 and the step of island figure 554 and 555 in the above described manner, be expected that output and rate of finished products improve and manufacturing cost reduces.

[embodiment 5]

Illustrate that the silicon thin film described in the present invention's first structure is to realize that the present invention is necessary.In this embodiment, explanation is used for example of the present invention with the silicon thin film of the mode crystallization that is different from embodiment 2.

Among Fig. 5, obtain state shown in Fig. 5 C (when the heat treatment of carrying out crystallization finishes) after, remove the lip-deep oxide-film 503 of crystal silicon film.After having removed oxide-film 503, utilize KrF (wavelength 248nm), XeCl (wavelength 308nm) etc. to anneal as the excimer laser of excitation gas.Laser annealing step carried out before or after silicon thin film is processed into the island figure.

By above-mentioned laser annealing, residue in a small amount of amorphous component crystallization in the crystal silicon film, the degree of crystallinity of crystalline silicon significantly improves.System display of the present invention even can utilize the silicon thin film of such acquisition to form.The advantage of this embodiment is, can form system display on cheap glass substrate,, can reduce manufacturing cost that is.

Yet implementing the optimal pattern of the present invention is to adopt the TFT that has utilized the silicon thin film described in the embodiment 1.Preferably only under must be, utilize present embodiment with situation as low heat resistant substrates such as glass substrates.

Step described in the embodiment 1 can combine with the step of present embodiment.That is, can adopt this structure, promptly after laser annealing, carry out the absorption technology of catalytic elements.In this case, can form the silicon thin film of high-crystallinity.

[embodiment 6]

Utilize the present invention to make the example of the active matrix substrate (making the substrate of that side of semiconductor element) of reflective type liquid crystal display device with reference to Figure 18 A-18C explanation below.

At first, about having the substrate of insulating surface, prepare the glass substrate 3000 that is deposited with the silicon oxide film bottom on it.Quartz substrate, silicon chip, ceramic substrate etc. all can replace glass substrate 3000.

Then, utilize plasma CVD method or low pressure chemical vapor deposition method to form the amorphous silicon film 3001 of thick 10-75nm.Can use for example Si _xGe _1-xSiliceous amorphous semiconductor films such as (0＜x＜1) replaces amorphous silicon film.

Then, utilize the Japanese unexamined special permission openly to equal disclosed technology in 8-78329, make amorphous silicon film 3001 crystallizations.Disclosed feature is to pass selectively to mix catalytic elements make crystal be arranged essentially parallel to the zone (being called lateral growth region) of substrate growth in amorphous silicon film in the document.

In the document, although apply as the method for mixing nickel with solution, feature of the present invention is to utilize ion implantation to mix nickel.

At first, on amorphous silicon film 3001, form thick 50-150nm silicon oxide film system shelter dielectric film 3002.Then composition this shelter dielectric film 3002, provide opening portion 3003 in the zone that will become peripheral circuit.Although only show an opening portion among the figure, in fact formed several opening portions.

Then, utilize ion implantation (being also referred to as the ion incidence method) to mix nickel.At this moment, the dosage of ion is adjusted to 1 * 10 ¹²-1 * 10 ¹⁵Atom/cm ²(preferably 2 * 10 ¹³-2 * 10 ¹⁴Atom/cm ²) (Figure 18 A).

When utilizing ion implantation to mix nickel resembling present embodiment, the width that the opening portion that provides in the dielectric film is provided is that about 0.25-2 μ m are enough to.That is, even can in forming the opening portion of fine pattern, mix quite a large amount of nickel.

In this embodiment, the width stuck-at-.5 μ m of the minimum slit of opening portion.So, in ion implantation step subsequently, can be directly proportional with dosage changes the amount of introducing nickel.

By this ion implantation step, formed nickel and mixed district 3004.The scale of the nickel of introducing in this ion implantation step shown in Figure 18 A is shown " a ".

Then, remove shelter dielectric film 3002 after, provide and shelter dielectric film 3005, form opening portion 3006 in the zone that will become the PEL (picture element) matrix circuit.In this case, utilize ion implantation to mix nickel, mix district 3007 to form nickel.The scale of the nickel of introducing in the ion implantation step shown in Figure 18 B is shown " b ".

Realized shown in Figure 18 B in nitrogen, oxygen or nitrogen atmosphere, carrying out the heat treatment of 4-24 hours (being generally 8-15 hours), so that amorphous silicon film 3001 crystallizations behind the state 500-700 ℃ (being generally 550-650 ℃).By this heat treatment, obtained lateral growth region 3008 and 3009 (Figure 18 C).

At this moment, the growth of lateral growth region 3008 distance is represented by " A ".That is, shown in Figure 18 A in the ion implantation step by realizing that growth distance mixes nickel for the introducing amount " a " of " A ".In addition, in horizontal peaceful coexistence district 3009, shown in Figure 18 B in the ion implantation step by realizing that the growth distance mixes nickel for the introducing amount " b " of " B "

In lateral growth region 3008 and 3009 the crystal structure, the needle-like or the column crystal that being basically parallel to the substrate growth have been assembled.And, also have a feature, the growth parallel to each other substantially of each acicular crystal, and as seen in same direction growth (being arranged side by side towards fixed-direction).In addition, utilize SIMS (ion microprobe) to confirm, contain about 5 * 10 in each crystal ¹⁸-1 * 10 ¹⁹Atom/cm ³Nickel.

The district 3010 and 3011 that is mixed with nickel becomes crystal region, wherein contains the nickel of high concentration.Uncrystallized amorphous area (amorphous area) is arranged except that the district of district 3008-3011 is still residual.

Then, remove and shelter dielectric film 3005, form photoresist mask 3012.Then, composition forms opening 3013-3015.At this moment, opening portion 3013 and 3014 is provided in the district in neighbouring element formation district (will become the district of the active layer of the TFT among this embodiment).Be used under opening portion 3013 and 3014, forming the floor (nickel is absorbed the district) of phosphorus element-containing with subsequent step.

In the district of the bottom electrode that will in subsequent step, become additional capacitor, form opening portion 3015.In this embodiment, mix phosphorus so that the part of the active layer of conduction is used as the bottom electrode of additional capacitor.

Incidentally, also can manufacture by composition and shelter dielectric film 3005 rather than newly form the photoresist mask to form the structure of necessary opening.In this case, also can be with this opening portion that in following P ion implantation step, mixes nickel.

Then, in this case, utilize ion implantation or plasma doping method to mix P (phosphorus) ion.In the doping step of this embodiment, accelerating voltage is 5-25KV, and ion dose is 1 * 10 ¹⁵-8 * 10 ¹⁵Atom/cm ²(be preferably 5 * 10 ¹³-1 * 10 ¹⁵Atom/cm ²).

Thus, mix at the P ion that to have mixed concentration in district's (after this be referred to as phosphorus and mix the district) 3016-3018 be 5 * 10 ¹⁹-2 * 10 ²¹Atom/cm ³The P ion.Thus, phosphonium ion mixes district 3016-3018 and forms amorphous (Figure 19 A).

In the structure of this embodiment, be incorporated into phosphorus and mix the absorption that the P ion of distinguishing in 3016 and 3017 is used for catalytic elements.Be incorporated into phosphonium ion and mix the P ion of district in 3018 and be used to make silicon fiml to have N type conduction type, so that this film forms the bottom electrode of additional capacitor.

Similarly,, form the zone of absorbing nickel by P elements, can form the N type conductive layer of the bottom electrode that will become additional capacitor simultaneously, thereby simplify manufacturing step according to this embodiment.Certainly, phosphorus mixes the effect that district 3018 also has the absorption catalytic elements.

After the P ion mixes the step end, remove photoresist mask 3012, and in blanket of nitrogen, heat treatment 2-24 hours (being generally 8-15 hours) under the temperature of 400-700 ℃ (being generally 600 ℃) makes the nickel that residues in lateral growth region 3008 and 3009 move to phosphorus and mixes in the district 3019-3021.At this moment, phosphorus mixes district's 3019-3021 crystallizations again (Figure 19 B).

Thus, residue in nickel in lateral growth region 3008 and 3009 and mixed district 3019-3021 by phosphorus and absorb, and obtained the lateral growth region 3022 and 3023 that nickel concentration has reduced.Incidentally, the gettering step of P elements is disclosed in the Japanese patent application flat 9-94607 that the inventor equals application on March 27th, 1997.

The inventor is that after the step, contained nickel concentration is reduced to maximum 5 * 10 in the lateral growth region 3022 and 3023 shown in Figure 19 B by the result that SIMS (ion microprobe) confirms ¹⁷Atom/cm ³(than the also little value of lower limit that detects, so can not measure).

At this moment, owing to being inhaled into phosphorus, mixes in the district 3019-3021, in nickel so these districts become the district that contains high concentration of nickel.According to the analysis of SIMS, can confirm that nickel concentration wherein is 1 * 10 ¹⁸-1 * 10 ²⁰Atom/cm ³

Yet, even being present in subsequently, will mix in the district 3021 in nickel as the phosphorus of the bottom electrode of additional capacitor, this district is also out of question as bottom electrode.Phosphorus mixes district 3019 and 3020 and is not used in channel formation region (can not be used as source/drain region) at least.Like this, because when forming active layer, phosphorus mixes district 3019 and 3020 and is removed entirely basically, so the existence of nickel can not cause problem.

After obtaining the state shown in Figure 19 B in this way, the composition silicon fiml forms active layer 3024-3026.Active layer 3024 and 3025 becomes the N type TFT and the P type TFT of the cmos circuit of main composition peripheral circuit respectively.Active layer 3026 becomes the pixel TFT (being N type TFT among this embodiment) that constitutes the PEL (picture element) matrix circuit.

During composition, require to remove the end of mixing the part and the lateral growth region in district as nickel.This is because the nickel of suitable high concentration is contained in these districts in very narrow zone, so these districts of corrosion in corrosion step subsequently at first and exist the possibility of polluting liquid reagent etc.

During composition,, in bottom (counterdie or quartz substrate surface), form a step owing at first corrode the end that nickel mixes district and lateral growth region.Particularly, because this step that nickel mixes in the district tends to become big, so must be noted.

Then, removal is formed at the lip-deep oxide (not shown) of silicon fiml.Because this oxide on surface has absorbed the contamination in the silicon fiml etc., so can obtain clean silicon fiml surface by removing this oxide.

Then, utilize plasma CVD method, directly formation will become the silicon oxide film 3027 of gate insulating film, thick 10-150nm.Can certainly use low pressure chemical vapor deposition method, sputtering method etc.Ecr plasma CVD method or high density ion CVD method also are effective (Figure 19 C) in addition.

Then, form by aluminium or mainly contain the electrode pattern 3028-3031 that the material of aluminium is made.Electrode pattern 3028-3030 is respectively the original shape of the gate electrode that constitutes cmos circuit or pixel TFT.Electrode pattern 3031 is the top electrode original shape (Figure 20 A) of additional capacitor.

Because this embodiment adopts three grid TFT to make pixel TFT, thus electrode pattern 3030 three shown in being divided into, but they are actually and are connected with each other, and are same electrode.

After having obtained the state shown in Figure 20 A in this way, then carry out two step anodic oxidation steps.Incidentally, the step that (phosphorus (P) or boron (B)) injects from the anodic oxidation to the ion of the following stated comes from openly flat 7-135318 disclosed technology of Japanese unexamined special permission by the inventor etc.So details etc. see also this document.

After forming electrode pattern 3028-3031, at first carry out anodic oxidation, the anode oxide film 3032-3035 of formation porous with 3% oxalic acid solution.Then, carry out anodic oxidation, form atresia anode oxide film 3036-3039 with containing 3% tartaric 1,2-ethylidene alcoholic solution.After twice anodic oxidation step, limit the top electrode 3043 of gate electrode 3040-3042 and additional capacitor.

Obtained in this way shown in Figure 20 B to utilize gate electrode and porous anodic oxide film to make mask behind the state, carried out the dry etching of gate insulating film 3027.By this step, form gate insulating film 3044-3047, gate insulating film 3047 is as the capacitor insulating film (Figure 20 C) of additional capacitor.

Then, as Figure 20 D, remove porous anodic oxide film 3032-3035, the P ion that carries out high acceleration injects and hangs down the P ion injection of acceleration.By this step, form source region 3048, drain region 3049, a pair of low concentration impurity district (being also referred to as the LDD district) 3050 and the channel formation region 3051 of N type TFT.

In addition, owing to pixel TFT is made of N type TFT, so formed source region 3052, drain region 3053, a pair of low concentration impurity district 3054 and the channel formation region 3057-3059 of pixel TFT.

At this moment, the P ion also is incorporated in the active layer of P type TFT, so, has just formed the district that contains the P ion 3060 and 3061 that concentration can be compared with above source/drain region, reaches the district that contains the P ion 3062 that concentration can be compared with above low concentration impurity district.The P ion is not incorporated in the district 3063, and the district of being somebody's turn to do keeps previous added P ion concentration.Yet in fact this district is integral with pixel TFT and drain region 3053.

Then, provide photoresist mask 3064, only expose P type TFT, the B ion that carries out high acceleration injects and hangs down the B ion injection of acceleration.By this step, the P ion 3060-3062 that contains shown in Figure 20 D all converts the P type to, has formed source region 3065, drain region 3066, a pair of low concentration impurity district 3067 and the channel formation region 3068 (Figure 21 A) of P type TFT thus.

Utilize above-mentioned ion implantation step, can only form source region/leakage of N type TFT and P type TFT by a step pattern step.

Then, remove photoresist mask 3064, arbitrary method for annealing or these method combinations by in furnace annealing, laser annealing and the lamp annealing activate the P ion and the B ion that are injected.When activating, inject unordered being repaired of active layer degree of crystallinity that causes because of ion.

Then, form the stacked film that silicon oxide film and silicon nitride film constitute, as first interlayer dielectric 3069.After forming contact hole, form source electrode 3070-3072, drain electrode 3073 and 3074 (Figure 21 B).

Then, form the organic resin film (polyimides, polyamide, polyimides amide (polyimide amide), acrylic acid etc.) of thick 0.5-3 μ m (being preferably 1.5-2.5 μ m) as second interlayer dielectric 3075.The distinguishing feature of organic resin film is relative dielectric constant lower (being about 2.0-3.4).Thus, the parasitic capacitance between can greatly reducing to connect up.That is, when formation needs the circuit of high-frequency drive such as logical circuit, can suppress the reduction of operating rate effectively.

Then, in second interlayer dielectric 3075, form contact hole, and form pixel capacitors 3076.At this embodiment, pixel capacitors 3076 by aluminium or the material that mainly contains aluminium make.

At last, in nitrogen atmosphere, heat-treat, the whole TFT that is obtained is carried out hydrogenization, to reduce the dangling bonds in the active layer.In this way, finish active matrix substrate shown in Figure 21 C at same substrate integrated CMOS circuit and pixel TFT.

After this, utilize known unit number of assembling steps, liquid crystal layer is clamped in above-mentioned active matrix substrate and relative substrate centre after, just formed reflection-type liquid-crystal display device.

Design to for example liquid crystal material or cell gap etc. can suitably be determined by the operator.Although this embodiment has adopted the structure of black mask at opposite side, can revise this structure, make black mask be arranged at the position that needs of active matrix substrate side.

Among this embodiment, more considerable is that the growth distance of lateral growth region differs from one another.

For example, in lateral growth region, even the different crystallinity according to the position is also slightly different in the same area.In this case, if a plurality of TFT is formed in the lateral growth region, then the electrical characteristics between two TFT that separate can be different.

Yet the nuance on this specific character is out of question to the circuit of the circuit of Analog signals or high-frequency drive.So, require that the distance with needs forms lateral growth region at the position of needs, form one group of TFT thus with trickle characteristic difference.

The present invention is a utmost point otherwise effective technique for this demand.And, mix district's area occupied owing to can utilize ion implantation greatly to reduce catalytic elements, so can greatly improve the degree of freedom of circuit design.

So from the development trend of following semiconductor circuit, obviously the present invention is for being processed to form and being had the high-frequency circuit etc. of very high operating rate extremely effective by hyperfine.

[embodiment 7]

Although embodiment 1 or 6 usefulness aluminium or the material of mainly being made up of aluminium are made gate electrode, also can make gate electrode with a kind of crystal silicon film of conduction type.

In addition, can also use for example metal materials such as titanium, tantalum, tungsten or molybdenum, the metal silicide of the compound of metal material and silicon etc. is made gate electrode.

[embodiment 8]

Among this embodiment, explanation is controlled the example of the growth distance of lateral growth region by the incorporation of controlling catalytic elements (nickel) with the method that is different from embodiment.

Among Figure 22 A, 3100 expression glass substrates provide counterdie on it, 3101 expression amorphous silicon films.Dielectric film 3102 is sheltered in formation, forms opening portion 3103 and 3104 then.

At this moment, the amount of the nickel that mixes of the width control of the minimum slit by changing opening.Among this embodiment, the minimum slit width of peripheral circuit is by " a " expression, and the minimum slit width of PEL (picture element) matrix circuit is represented by " b ".

At this moment, inject nickel by ion implantation.Injection condition can be identical with embodiment 1.Among this embodiment, be that 10KV, dosage are 2 * 10 at accelerating voltage ¹⁴Atom/cm ²Condition under carry out nickel ion and inject (Figure 22 A).

At this moment, owing to carry out the ion implantation step simultaneously, so the nickel concentration that is incorporated in opening portion 3103 and 3104 is mutually the same.Yet the nickel that forms by this ion implantation step mixes different and different with opening portion 3103 and 3104 minimum slit width of nickel incorporation in the district 3105 and 3106.

Obtaining shown in Figure 22 A behind the state, under the condition identical, heat-treating, making amorphous silicon film 3102 crystallizations with embodiment 1.Among this embodiment, carry out (Figure 22 B) heat treatment in 14 hours, carry out crystallisation step at 570 ℃.

Form lateral growth region 3107 and 3108 by this crystallisation step.At this moment, the growth of lateral growth region 3107 distance is by " A ' " expression, and the growth of lateral growth region 3108 distance is by " B ' " expression.Among this embodiment, be designed to the satisfied B ' that concerns〉A '.

Among this embodiment, minimum slit width " a " is specified to the growth distance that makes the lateral growth region 3107 after the crystallization and becomes " A ' ", and minimum slit " b " is specified to the growth distance that makes lateral growth region 3108 and is " B ' ".For this reason, must be in ion implanting conditions (10KV, 2 * 10 of this implementation column ¹⁴Atom/cm ²) under obtain this relation between minimum slit width and growth distance in advance.

Carry out so simultaneously under the situation of ion implantation step resembling this embodiment,, just can control the amount of mixing nickel so control minimum slit width, and further control the growth distance of lateral growth region because the nickel concentration that mixes is unified on whole substrate.Step subsequently can be identical with embodiment 1.

In addition, adopt under the situation of this structure of this embodiment, when the P ion implantation step that carries out subsequently shown in Figure 19 A, can utilize and shelter dielectric film 3102 and mix phosphorus as mask.Like this, just needn't provide the photoresist mask again, and save a pattern step, so can simplified manufacturing technique.

[embodiment 9]

Although embodiment 1-4 or embodiment 6 have showed the example of plane TFT as typical TFT structure, the present invention can adopt as putting upside down bottom gate type TFT such as irregular type TFT.

Therefore, no matter how the structure of semiconductor element (semiconductor device) all can use the present invention, the invention is not restricted to the semiconductor element of ad hoc structure.

[embodiment 10]

Among this embodiment, explanation is carried out the example of the ion implantation step of catalytic elements (nickel) by the structure that is different from embodiment 6.

Among Figure 23,3400 expression glass substrates, 3401 expression counterdies, 3402 expression amorphous silicon films, the resilient coating that 3403 expressions are made by silicon oxide film etc., 3404 expressions have the photoresist mask of opening portion.Resilient coating 3403 can utilize as vapour phase processes such as plasma CVD methods and form, and in some cases, can also utilize simple oxidation methods such as for example thermal oxidation or UV oxidation to form.

The characteristics of this embodiment are directly not inject catalytic elements in amorphous silicon film 3402, but inject catalytic elements by resilient coating 3403.In this case, need not, the profile adjustment of ion becomes to make peak value be arranged in amorphous silicon film 3402 in the time of ion can being injected.

Even in the structure of this embodiment, can in the big film 3402 of amorphous, form nickel and mix district 3405 and 3406 by making the ion implanting conditions optimization.According to the structure of this embodiment, because the damage that ion produces when injecting does not directly arrive amorphous silicon film 3402, so can avoid owing to damage the harmful effect that causes.In addition, can prevent that the impurity element (contained element etc. in the atmosphere) except that catalytic elements from injecting simultaneously when ion injects.

In addition, effectively utilize plasma CVD method to form the structure of amorphous silicon film 3402 and resilient coating 3402 continuously.In this structure, the surface that impurity is attached to amorphous silicon film 3402 can not take place, and together injected when ion injects.

Can also carry out the ion implantation step that the structure of this embodiment combines with the structure of embodiment 1 or 6.

[embodiment 11]

Although embodiment 1 or 6 usefulness ion implantation as the means of mixing the P ion, will illustrate the example with vapour phase processes among this embodiment.

Among this embodiment, the position that needs on the amorphous silicon film surface provides dielectric film, in this case, forms phosphorous film with plasma CVD method.This film can mix hydrogen phosphide (PH by forming in the gas at film ₃) wait formation.

Thus, with P elements gettering (heat treatment) time, the district that is formed with film is as the gettering district.

[embodiment 12]

Among this embodiment, explanation is mixed the example of P ion method with liquid phase method.Particularly, form the film that is typically PSG (phosphorosilicate glass) by the solution coating.

In addition, in this case, provide insulating barrier, at this moment, apply as the raw-material solution of PSG, and carry out spin coating, thereby form phosphorous film at the position that needs of amorphous silicon film.Utilize this method, can form the gettering district.

[embodiment 13]

Among this embodiment, be, carry out the gettering step, replace the P elements gettering step of embodiment 6 by halogen with the example that illustrates.Use the reference number identical in case of necessity with embodiment 1.

At first, identical with the step of embodiment 1, obtain state shown in Figure 24 A.This state is equivalent to state shown in the embodiment 18C.

Then, behind state shown in acquisition Figure 24 C, in the atmosphere that contains the halogen family element, heat-treat.Among this embodiment, oxygen (O ₂) contain the hydrogen chloride (HCl) (Figure 24 B) of 0.5-10vol% (being generally 3vol%) in the atmosphere.

Except that HCl, can comprise HF, NF with being selected from ₃, HBr, Cl ₂, ClF ₃, BCl ₃, F ₂, Br ₂Deng in one or more contain the halogen family elemental substance.In addition, also can use the hydride of halogen.

Preferably heat-treating, so that carry out the gettering of chlorine effectively above under 700 ℃ the temperature.This temperature is generally 800-1000 ℃ (this embodiment is 950 ℃).Handle by this, thoroughly remove or reduced nickel in the whole crystal silicon film.

The inventor's SIMS (ion microprobe) found that, shown in Figure 24 B after the step, contained nickel concentration is minimum in the lateral growth region 3501 and 3502 is reduced to 5 * 10 ¹⁷Atom/cm ³(being lower than the lower limit of detection) so can not measure.

And halogen enters into lateral growth region inside by this heat treatment.The concentration of the interior halogen of active layer (lateral growth region) is 1 * 10 like this, at last ¹⁵-1 * 10 ²⁰Atom/cm ³

The inventor analyzes lateral growth region 3501 and 3502 by TEM (transmission electron microscope), and the result proves, many bar-shaped or flat rhabdoliths that are arranged side by side trend towards a specific direction and flock together in the crystal structure in this district.

The characteristics of this crystal structure and above-mentioned lateral growth region are much at one.Yet, by the inventor's various analyses, can draw to draw a conclusion, lattice is continuous in the border (product circle) between each rhabdolith (can be called acicular crystal), so the density of crystal boundary (conformity) is fine and electric passive.

Proved the TFT of the active layer of the crystal silicon film with this crystal structure, its electrical characteristics are better than being formed at the MOSFET on the monocrystalline silicon.The concrete condition of this crystal structure is seen the day body patent application flat 8-335152 of application on November 29th, 1996.

Obtaining in this way shown in Figure 24 B behind the state, the composition silicon fiml is to form active layer 3503-3505.Active layer 3503 and 3504 becomes the N type TFT and the P type TFT of the cmos circuit of main composition peripheral circuit respectively.Active layer 3505 becomes the pixel TFT that constitutes the PEL (picture element) matrix circuit.

Then, utilize plasma CVD method, formation will become the silicon oxide film 3506 of gate insulating film, and its thickness is 10-150nm, and heat-treat above under 700 ℃ the temperature again.At this moment, the preferably aforesaid atmosphere that contains the halogen family element of heat-treating atmosphere.In this case, treatment conditions can identical with above-mentioned condition (Figure 24 C).

In addition, when heat treatment finishes, be increased in the heat treatment in the inert atmosphere, to improve the film quality of gate insulating film 3506 effectively.

Hope is further removed the nickel that residues in the active layer by this heat treatment.In addition, form heat oxide film at the interface of 3506 of active layer 3503-3505 and gate insulating films, and can obtain the excellent interface between active layer and gate insulating film, this interface does not almost have interfacial state etc.After this, can make semiconductor device with step similar to Example 6.

[embodiment 14]

Among the present invention, except that ion implantation shown in Figure 2, can adopt as not with photoresist mask directly in amorphous silicon film, mix the method for catalytic elements, this constitutes another embodiment.

About the method, have a kind of as a technology to the FIB of small luminous point radiation ion (focused ion beam) method.According to this technology, utilize the converging ion beam that contains catalytic elements directly to carry out composition, so that mix the district in the catalytic elements of desired area formation required form.

According to this embodiment, can simplify the step of formation photoresist mask and the step of composition, so can reduce manufacturing cost, improve output.

[embodiment 15]

Among this embodiment, will some examples that combine with the interlayer dielectric shown in the embodiment 2 (first to the 3rd) be described.

At first, among Fig. 7 D, do first and second interlayer dielectrics 557 and 563 with polyimides, as mainly contain aluminium wiring 558-562 bottom and as the bottom of the black mask of making by titanium film 564.Make the 3rd interlayer dielectric 565 with acrylic acid, as the bottom of pixel capacitors 566.

Under the inventor's experiment condition, because the film growth temperature (300 ℃) of wiring 558-562 and black mask 564 is slightly higher than acrylic acid heat resisting temperature (200 ℃), so preferably adopt the polyimides (heat resisting temperature is about 350-400 ℃) that can tolerate as the film growth temperature of bottom.Because pixel capacitors 566 at room temperature forms, so there is the acrylic acid of low heat resistant can be used as bottom.Yet this structure only limits to pixel capacitors 566 by the material with low film growth temperature (as being lower than the material that forms film under acrylic acid heat resisting temperature) ITO situation about making for example.

This structure has the following advantages.

(1) because acrylic acid has light sensitivity, direct composition, and needn't utilize the photoresist mask, so can simplify manufacturing step.

(2) because acrylic acid is more cheap than polyimides, hydrogen can reduce manufacturing cost.

(3) good than between ITO and polyimides of the adhesion between ITO and acrylic acid.

(4) because the acrylic acid planarization is good,, be added on the pixel capacitors so can produce uniform electric field.

About other example, all interlayer dielectrics all can be used polyimides, or all interlayer dielectrics all can be used acrylic acid.Yet when all interlayer dielectrics were made with acrylic acid, prerequisite was, form acrylic film after, the step of being carried out should be carried out being lower than under the temperature of acrylic acid heat resisting temperature.

[embodiment 16]

The present invention can be applied to any semiconductor device, and any semiconductor device all is included in the range of application of the present invention as long as its circuit utilization has the on-chip TFT of insulating surface to be formed.This semiconductor device comprises only as logical circuit and the device that is used for as displays such as active matrix type electro-optical devices as IC and VLAI etc.

Especially, about the active array type electro-optical device, utilize the system display that comprises bist logic circuit shown in Figure 1, the present invention can be applied to active-matrix liquid crystal display device, active matrix EL display device, active matrix EC display device etc.

These Actire matrix display devices are divided into transmissive display spare and reflection type display device substantially.For example, transmission-type liquid crystal display device is that backlight is arranged at active matrix substrate (it is provided with the substrate of TFT) dorsal part, the device of the light recognition image by seeing the transmission display unit.Reflective type liquid crystal display device is to be set at pixel capacitors reflection on the active matrix substrate from the light of penetrating that the face side of active matrix substrate is gone into, but by seeing the just device of recognition image of reverberation.

Although the TFT structure of transmissive display spare and reflection type display device does not have much difference, the characteristics that can know are to form the material difference of pixel capacitors between the two.For example, when making transmissive display spare, just enough with the pixel capacitors 1411 among electrodes such as the transparent ITO mapping 14A.And when making reflection type display device, utilizing the opaque electrode with high reflectance to make pixel capacitors 1411 can.

In this way, by changing the structure of TFT a little, the present invention just can be used for transmission-type and reflection type display device.Especially, because therefore the aperture has the design freedom advantage higher than transmissive display part than being out of question for reflection type display device.For example, in transmission-type liquid crystal display device, pixel region almost is made of the window portion that light passes through, as graphical display area 1414.On the other hand, in the reflective type liquid crystal display device, because other circuit can be formed at the dorsal part of image displaying area, so integrated level can further improve.

[embodiment 17]

In this embodiment, the example of the pixel structure of formation PEL (picture element) matrix circuit as shown in figure 25.Yet, for simplified structure has omitted pixel capacitors.

Among Figure 25,11 expression active layers are equivalent to the active layer 3026 among Figure 19 C.Among this embodiment, leaking side formation active layer 11, make it to extend in all pixels, the characteristics of this embodiment are that active layer also is used as the bottom electrode 12 of additional capacitor.

Grid line 13 by the gate insulating film setting thereon.Grid line 13 is equivalent to the gate electrode 3042 among Figure 20 B.In addition, the top electrode 14 of additional capacitor is formed at the zone except that grid line 13.Top electrode 14 is equivalent to the top electrode 3043 among Figure 20 B.

In this case, top electrode 14 is arranged to almost identical with the active layer that will become bottom electrode shape, and forms the additional capacitor that almost is equivalent to the pixel area occupied.The top electrode 14 of adjacent pixel be electrically connected to each other (top electrode and grid line are also got connection, so that do not intersect with grid line).That is, the top electrode of the additional capacitor in all pixels keeps identical current potential.

Then, by first interlayer dielectric, on grid line 13 and additional capacitor top electrode 14, form source electrode (source line) 15 and drain electrode 16.These electrodes are equivalent to source electrode 3072 and the drain electrode 3074 among Figure 21 B.

Although not shown, shown in Figure 21 C, form interlayer dielectric 3075 and pixel capacitors 3076, and after carrying out known unit number of assembling steps, just finished reflective type liquid crystal display device.When adopting the structure of this embodiment,, also can guarantee to utilize the maximum of the additional capacitor in this district even pixel region diminishes.

Be equivalent to XGA if structure shown in this embodiment made, then be difficult to utilize lateral growth region to form the active layer that is arranged at the TFT in the PEL (picture element) matrix circuit.This is because pixel size is very little among the XGA, about 30 μ m ²So, mix the district if utilize conventional method to form big nickel, can not mix the bottom electrode that the district forms additional capacitor by removal so.

Yet, among the present invention, provide nickel to mix the district owing to adopted under source electrode 15 grades, so the problems referred to above can not take place.

[embodiment 18]

In the present embodiment, explanation is applied the present invention to be different from the example of the reflective type liquid crystal display device of embodiment 13.Figure 26 A is the top view (yet, omitted relative substrate, liquid crystal layer and pixel capacitors) of this device, and Figure 26 B is its profile.

Among Figure 26 A and the 26B, 20 expression active layers, 21 expression gate electrodes (grid line), 22 expression source electrodes (source line), 23 expression drain electrodes.This moment drain electrode 23 form big (distinguishing shown in the dotted line), so this electrode extends on the whole surface of pixel region.This drain electrode 23 is as the bottom electrode of additional capacitor.

Form silicon nitride film 24 (seeing Figure 26 B) on drain electrode, and form titanium film 25 on silicon nitride film, titanium film 25 is as the top electrode of additional capacitor, and silicon nitride film 24 is clamped between drain electrode 13 and the titanium film 25, forms additional capacitor.

In fact, shown in Figure 26 B, form pixel capacitors 26 to shelter whole pixel.Form the alignment films (not shown) then thereon.Here, they are called as active matrix substrate on the whole.

And, shown in Figure 26 B, preparing relative substrate, this substrate is for being formed with the substrate of nesa coating 28 and alignment films (not shown) on transparent substrate 27.As required, colour filter, black mask etc. can be arranged on the relative substrate.

Liquid crystal layer 30 sealed material 29 sealings are held between relative substrate and the active matrix substrate.Liquid crystal material can be according to suitably changing as liquid crystal drive patterns such as ecb mode or host and guest's patterns.

Among this embodiment, liquid crystal layer is not arranged on the peripheral circuit, forms parasitic capacitance to prevent 28 of nesa coatings that enclose circuit and relative substrate side outside.Certainly, the present invention can be applicable to liquid crystal layer and is arranged at the whole lip-deep structure of substrate.

In embodiment 13 and 7, although the example that constitutes reflective type liquid crystal display device has been described, needless to say, the present invention can also be applied to transmission-type liquid crystal display device.

Because the present invention has the bigger effect of the circuit design degree of freedom, so more effective than very for the aperture of improving transmissive display spare.

The present invention also can be applicable to the electro-optical device except that liquid crystal display device.This electro-optical device comprises EL (electroluminescence) display device, EC (electric look) display device etc.

[embodiment 19]

Among this embodiment, utilize the application product of the electro-optical device shown in the embodiment 8 with reference to Figure 16 A-16E explanation, wherein embodiment 8 can use an example of the present invention.

Utilize semiconductor device of the present invention to comprise (numeral) video frequency camera, (numeral) static gamma camera, crown formula display, auto-navigation system.Personal computer, portable data assistance (automobile computer, portable phone etc.) etc.

Figure 16 A shows a kind of automobile computer, it by main body 2001, videotape part 2002, visual receiving unit 2003, console switch 2004 and display device 2005 and constitute.Be applied to display device 2005 in the present invention,, just can realize the cassette automobile computer so that when being integral with display control circuit, computing circuit etc.

Figure 16 B has showed a kind of crown formula display, and it is made of main body 2101, display device 2102 and crank section 2103.When the present invention is applied to display device 2102, can greatly reduce this display device.

Figure 16 C has showed a kind of auto-navigation system, and it is made of main body 2201, display device 2202, console switch 2203 and antenna 2204.Because the message transmission from satellite arrives auto-navigation system, so must carry out the signal processing of the circuit of high driving frequency.When the present invention is applied to display device 2202, can further reduces the size of auto-navigation system, and reduce cost.

Figure 16 D has showed a kind of portable phone, and it is made of main body 2301, sound (audio frequency) output 2302, sound (audio frequency) importation 2303, display device 2304, console switch 2305 and antenna 2306.When the present invention is applied to display device 2304, just digital display monitor can be installed.

Figure 16 E has showed a kind of video frequency camera, and it is made of main body 2401, display device 2402, sound (audio frequency) importation 2403, console switch 2404, battery 2405 and visual receiving unit 2406.When the present invention is applied to display device 2402, can greatly simplifies device architecture, thereby can realize the very small dimensions device.

As mentioned above, of the present inventionly be of wide application generally, the present invention can be applied to the display media of any occasion.Because application of the present invention can make Active Matrix Display self have various functions, so can greatly reduce the size of electrophone spare.Soon in the future, just can realize the portable electro-optical device of cassette by this system display.

The structure of the utmost importance that realizes first invention of the present invention is the silicon thin film that obtains to have the unique crystal structures body, and this film is to absorb technology by the catalytic elements of the crystal silicon film that utilizes the catalytic elements crystallization being utilized halogen to obtain.

Utilization has following characteristics by the TFT of the silicon thin film that embodiment 2 described manufacturing steps form, and has subthreshold value coefficient and the high-field effect mobilance that can compare with the MOSFET that utilizes monocrystalline silicon.The formed silicon thin film of crystal structure body that constitutes by a plurality of bar-shaped or flat rhabdoliths of cluster, have to make to utilize and self suppress the effect of short-channel effect, even TFT makes very for a short time, also can realize high withstand voltage and high operation speed characteristic, and not utilize channel doping method etc.

Having excellent performance by utilization is the wide TFT of driving frequency and operating voltage range, can form high-frequency drive TFT and high withstand voltage drive TFT on same substrate.

The structure of second invention is, utilizes ion implantation as mixing the method for catalytic elements, requiring the position to form the lateral growth region with required growth distance.Utilize this technology, even be the minimum TFT of 0.25-0.7 μ m when constituting by channel length, also can form with circuit design is different and have the lateral growth region of suitable dimension, so can easily unify device property at circuit.

Owing to can realize above-mentioned effect, thus can form a kind of semiconductor device, wherein have insulating surface substrate on be formed with the logical circuit that constitutes by TFT.In addition, can even realize having the semiconductor device of the bist logic circuit that comprises logical circuit, drive circuit and pixel circuit, wherein high-frequency drive TFT and high withstand voltage drive TFT are contained on the same substrate.

Because except that PEL (picture element) matrix circuit and drive circuit, semiconductor device of the present invention is also carrying display control circuit, memory circuit and finally can comprise the logical circuit of computing circuit, so it can be used as the many and light system display of function.And high frequency drive circuit is designed so that operating voltage can not become bigger than required voltage, so electrical power consumed is quite low.

And, for example with this semiconductor device application in liquid crystal display device, or when utilizing the application product of this display device to make display monitor, can provide volume little, in light weight and cheap product.

Claims (5)

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

Form amorphous silicon film having on the substrate of insulating surface;

Promote the catalytic elements of silicon fiml crystallization optionally to add described amorphous silicon film to being used for;

Make of the starting point crystallization of described amorphous silicon film by heat treatment, form a plurality of lateral growth region that crystalline silicon film is made from the catalytic elements Adding Area;

Form active layer, the channel formation region territory is only formed by described lateral growth region at least in each active layer;

On each active layer, form silicon oxide film; With

By in containing the atmosphere of halogens, heat-treating, remove the catalytic elements in each active layer and described active layer carried out thermal oxidation;

The method that the step of wherein adding catalytic elements is injected by ion or the method for plasma doping are carried out, and the concentration of the catalytic elements of adding at least one part on same substrate is different with the concentration that another is added catalytic elements in the zone of catalytic elements.

2. method of making semiconductor device may further comprise the steps:

Form amorphous silicon film having on the substrate of insulating surface;

Promote the catalytic elements of silicon fiml crystallization optionally to add described amorphous silicon film to being used for;

Make of the starting point crystallization of described amorphous silicon film by heat treatment, form a plurality of lateral growth region that crystalline silicon film is made from the catalytic elements Adding Area;

Form active layer, the channel formation region territory is only formed by described lateral growth region at least in each active layer;

On each active layer, form silicon oxide film; With

By in containing the atmosphere of halogens, heat-treating, remove the catalytic elements in each active layer and described active layer carried out thermal oxidation;

Wherein adding the step of catalytic elements carries out by the method for ion injection or the method for plasma doping; And, the catalytic elements of on same substrate, adding variable concentrations according to the length of raceway groove in the active layer.

3. according to the method for claim 1 or 2, wherein the length of the minor face in the zone of each interpolation catalytic elements is 0.01-1 μ m.

4. according to the method for claim 1 or 2, one or more elements in the wherein following group are selected as described catalytic elements: Ni, Co, Fe, Sn, Pb, Pd, Pt, Cu, Au.

5. according to the method for claim 1 or 2, one or more materials that contain halogen in the wherein following group are comprised in the described atmosphere that contains halogens: HCl, HF, NF ₃, HBr, Cl ₂, ClF ₃, BCl ₃, F ₂, Br ₂

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