Thin film transistor (TFT) and preparation method thereofTechnical field
The present invention relates to technical field of semiconductor device, more particularly to a kind of thin film transistor (TFT) and preparation method thereof.
Background technology
Thin film transistor (TFT) (ThinFilmTransistor, TFT) is a kind of key electronics in modern microelectronic technologyElement has been widely used in the fields such as flat-panel monitor at present.With printing technology come prepare thin film transistor (TFT) can poleThe earth reduces cost and improves production efficiency, great market value.
But existing printable semi-conducting material such as organic matter, carbon nano-tube film, metal oxide nanoparticles etc.Mobility it is not high (<10cm2/ Vs), and the technologies such as mainstream printing technology such as ink-jet, intaglio plate, silk-screen printing being currently knownPatterning resolution is relatively low (be more than 20 microns), this will cause the thin film transistor channel length (source-drain electrode distance) of printing compared withLong, the current density so as to cause the thin film transistor (TFT) of printing is relatively low, it is difficult to meet the driving requirement of OLED/QLED, this is limitThe major reason that the thin film transistor (TFT) of seal carving brush is applied in display field.
Invention content
Based on this, it is necessary to for the relatively low problem of the current density of above-mentioned conventional thin film transistor, provide a kind of electric currentThe higher thin film transistor (TFT) of density.
Specific technical solution is as follows：
A kind of thin film transistor (TFT), including substrate, the semiconductor layer in the substrate, on the semiconductor layerDrain electrode, source electrode and insulating layer and the grid on the insulating layer, the insulating layer are located at the drain electrode and the source electrodeBetween, the region that the semiconductor layer corresponds between the drain electrode and the source electrode is raceway groove, and the raceway groove is embedded with along ditchThe tape conductor that road width direction extends.
Raceway groove refers to corresponding to the semiconductor layer regions between source electrode and drain electrode in field-effect transistor, and channel length is leakageThe distance between pole and source electrode, orientation be source electrode to drain direction, channel width dimension is perpendicular to channel lengthDirection.When applying voltage on the grid in thin film transistor (TFT), pass through meeting in the spaced semiconductor layer of insulating layer with gridAccumulate carrier, when carrier accumulation to a certain extent, between source electrode and drain electrode electrical connection to the semiconductor layer will conducting, toThere is electric current to flow to by raceway groove from source electrode to drain.In the thin film transistor (TFT) of the present invention, since raceway groove is embedded with along channel width sideTo the tape conductor of extension, the conductivity of conductor is far above the conductivity of semiconductor, therefore tape conductor can direct short circuit both sidesChannel region, be equivalent to and reduce the distance between drain electrode and source electrode, substantially reduce length of effective channel.And film is brilliantThe current density of body pipe is inversely proportional to length of effective channel, thus can effectively improve the current density of thin film transistor (TFT), to make printThe thin film transistor (TFT) of brush can also meet the driving requirement of OLED/QLED well, greatly reduce production cost and improve lifeProduce efficiency.
The material of the tape conductor is metal mold carbon nanotube in one of the embodiments,；And/or
The material of the semiconductor layer is semiconductor type carbon nano-tube.
The quantity of the tape conductor is multiple, multiple tape conductor parallel intervals in one of the embodiments,Distribution.
The shape of the tape conductor is cuboid in one of the embodiments, and the width of the tape conductor isThe spacing of 30nm~1 μm, the two neighboring tape conductor is 30nm~1 μm.
The material of the substrate is glass, polyethylene terephthalate or silicon in one of the embodiments,；With/Or
The material of the source electrode, the drain electrode and the grid is metal, metal mold carbon nanotube, graphene or organic leadsBody.
The present invention also provides a kind of preparation methods of thin film transistor (TFT), include the following steps：
Substrate is provided, forms tape conductor on the substrate；
The semiconductor layer for covering the tape conductor is formed on the substrate；
Formed on the semiconductor layer drain electrode that is spaced apart of width direction along the tape conductor and source electrode andInsulating layer between the drain electrode and the source electrode；
Grid is formed on the insulating layer, obtains the thin film transistor (TFT).
The specific method for forming the tape conductor in one of the embodiments, is：Conductor is formed on the substrateLayer, etches the conductor layer to form the tape conductor.
The specific method for forming the conductor layer in one of the embodiments, is：In the substrate surface deposited concentrationFor the metal mold carbon nano-tube solution of 0.5mg/L~30mg/L, then takes out and perform etching so that in the substrate described in formationConductor layer.
The specific method for etching the conductor layer in one of the embodiments, is：Protection is formed in the conductor layerGlue-line makes the protection glue-line form the protection that multiple parallel intervals are distributed using nanometer embossing or interference photoetching technologyThen band performs etching and washes away the protection band using organic solvent and described band-like led with forming the multiple of parallel interval distributionBody.
The specific method for forming the semiconductor layer in one of the embodiments, is：It prints and partly leads on the substrateBuild carbon nanotube ink is to form the semiconductor layer.
Description of the drawings
Fig. 1 is the structural schematic diagram of the thin film transistor (TFT) of an embodiment；
Fig. 2 is the flow diagram of the preparation method of the thin film transistor (TFT) of an embodiment.
Specific implementation mode
To facilitate the understanding of the present invention, below with reference to relevant drawings to invention is more fully described.In attached drawingGive presently preferred embodiments of the present invention.But the present invention can realize in many different forms, however it is not limited to this paper institutesThe embodiment of description.Keep the understanding to the disclosure more thorough on the contrary, purpose of providing these embodiments isComprehensively.
It should be noted that when element is referred to as " being installed on " another element, it can be directly on another elementOr there may also be elements placed in the middle.When an element is considered as " connection " another element, it can be directly connected toTo another element or it may be simultaneously present centering elements.When an element is considered as " connection " another element, it canTo be directly to another element or may be simultaneously present centering elements.
Unless otherwise defined, all of technologies and scientific terms used here by the article and belong to the technical field of the present inventionThe normally understood meaning of technical staff is identical.Used term is intended merely to description tool in the description of the invention hereinThe purpose of the embodiment of body, it is not intended that in the limitation present invention.Term as used herein "and/or" includes one or more phasesAny and all combinations of the Listed Items of pass.
As shown in Figure 1, a kind of thin film transistor (TFT) 100 in better embodiment of the present invention, including substrate 10, it is set to substrateSemiconductor layer 20 on 10, the drain electrode 30 on semiconductor layer 20, source electrode 40 and insulating layer 50 and on the insulating layer 50Grid 60, insulating layer 50 be located at drain electrode 30 and source electrode 40 between, semiconductor layer 20 correspond to drain electrode 30 and source electrode 40 betweenRegion is raceway groove, and raceway groove is embedded with the tape conductor 22 extended along channel width dimension.
Raceway groove refers to corresponding to the semiconductor layer regions between source electrode and drain electrode in field-effect transistor, and channel length is leakageThe distance between pole and source electrode, orientation be source electrode to drain direction, channel width dimension is perpendicular to channel lengthDirection.When applying voltage on the grid 60 in thin film transistor (TFT) 100, partly led with grid 60 by the way that insulating layer 50 is spacedCarrier can be accumulated in body layer 20, when carrier accumulation to a certain extent, the source electrode 40 that is electrically connected with semiconductor layer 20 and drain electrodeIt will be connected between 30, to there is electric current to pass through raceway groove flow direction drain electrode 30 from source electrode 40.In the thin film transistor (TFT) 100 of the present invention, byThe tape conductor 22 extended along channel width dimension is embedded in raceway groove, the conductivity of conductor is far above the conductivity of semiconductor,Therefore tape conductor 22 can directly short circuit both sides channel region, be equivalent to reduce drain electrode the distance between 30 and source electrode 40,Substantially reduce length of effective channel.And the current density of thin film transistor (TFT) 100 is inversely proportional to length of effective channel, thus can haveEffect improves the current density of thin film transistor (TFT) 100, to make the thin film transistor (TFT) 100 of printing that can also meet OLED/ wellThe driving requirement of QLED, greatly reduces production cost and improves production efficiency.
In one embodiment, the material of tape conductor 22 is metal mold carbon nanotube.In one embodiment, semiconductorThe material of layer 20 is semiconductor type carbon nano-tube.Carbon nanotube has excellent mechanics and electric property, also, with carbon nanometerThe variation of pipe spiral way, carbon nanotube can show metallicity or semiconductive.It can be incited somebody to action using density gradient centrifugation methodSemiconductor type carbon nano-tube and metal mold carbon nanotube separation come, and two kinds of carbon nanotubes have been commercialized at present.SemiconductorType carbon nanotube has higher carrier mobility, is the ideal material for manufacturing transistor semiconductor layer.Further, band-likeThe material of conductor 22 and semiconductor layer 20 is single-walled carbon nanotube, and the distribution of diameter of single-wall carbon nano tube size is small, is lackedIt falls into less, there is higher uniformity consistency.
Optionally, the quantity of tape conductor 22 is multiple, the distribution of 22 parallel interval of multiple tape conductors.It is appreciated that bandShape conductor 22, which can run through semiconductor layer 20, can not also run through semiconductor layer 20.
Optionally, the shape of tape conductor 22 is cuboid, and the width of tape conductor 22 is 30nm~1 μm, two neighboringThe spacing of tape conductor 22 is 30nm~1 μm.In this way, length of effective channel L is equal between multiple two neighboring tape conductors 22Summation away from l, by adjusting the size of the width d of tape conductor 22, you can adjust the increase multiple of current density, such as work as d=lWhen, theoretically current density rises to 2 times in the case of being not provided with tape conductor 22, as d=3l, then theoretically current density4 times in the case of being not provided with tape conductor 22 are risen to, and so on.
Optionally, the material of substrate 10 is glass, polyethylene terephthalate or silicon.Optionally, source electrode 40, drain electrode30 and grid 60 material be metal, metal mold carbon nanotube, graphene or organic conductor.
The thin film transistor (TFT) 100 of present embodiment reduces drain electrode the distance between 30 and source electrode 40, substantially reducesLength of effective channel, thus the current density of thin film transistor (TFT) 100 can be effectively improved, to make the thin film transistor (TFT) 100 of printingAlso the driving requirement that can meet OLED/QLED well, greatly reduces production cost and improves production efficiency.
It is illustrated in figure 2 the flow diagram of the preparation method of the thin film transistor (TFT) of an embodiment of the present invention, the preparationMethod includes the following steps S1~S4：
S1, substrate 10 is provided, forms tape conductor 22 on the substrate 10.
S2, the semiconductor layer 20 for forming covering tape conductor 22 on the substrate 10.
S3, formed on semiconductor layer 20 along tape conductor 22 the drain electrode 30 that is spaced apart of width direction and source electrode 40 withAnd the insulating layer 50 between drain electrode 30 and source electrode 40.
S4, grid 60 is formed on insulating layer 50, obtain thin film transistor (TFT).
Then the preparation method of the thin film transistor (TFT) of present embodiment is existed by forming tape conductor 22 on the substrate 10The semiconductor layer 20 of covering tape conductor 22 is formed in substrate 10, to make tape conductor 22 be embedded at semiconductor layer 20, thenThe drain electrode 30 being spaced apart along the width direction of tape conductor 22 and source electrode 40 are formed on semiconductor layer 20 and positioned at drain electrodeInsulating layer 50 between 30 and source electrode 40, and form grid 60 on insulating layer 50 and obtain thin film transistor (TFT).In this way, due to raceway grooveIt is embedded with the tape conductor 22 extended along channel width dimension, the conductivity of conductor is far above the conductivity of semiconductor, therefore bandShape conductor 22 can directly short circuit both sides channel region, be equivalent to reduce drain electrode the distance between 30 and source electrode 40, substantiallyReduce length of effective channel.And the current density of thin film transistor (TFT) is inversely proportional to length of effective channel, thus can effectively improve thinThe current density of film transistor, to make the thin film transistor (TFT) of printing that can also meet the driving requirement of OLED/QLED, pole wellThe earth reduces production cost and improves production efficiency.
In one embodiment, the specific method for forming tape conductor 22 is：Conductor layer 202 is formed on the substrate 10, is carvedConductor layer 202 is lost to form tape conductor 22.Optionally, before forming conductor layer 202, substrate 10 uses acetone, isopropanolOr deionized water is cleaned, and nitrogen is used in combination to dry up.
In one embodiment, the material of tape conductor 22 is metal mold carbon nanotube, and the material of semiconductor layer 20 is halfConductor type carbon nanotube.Further, the material of tape conductor 22 and semiconductor layer 20 is single-walled carbon nanotube.Optionally,The quantity of tape conductor 22 is multiple, 22 parallel interval of multiple tape conductors distribution.Optionally, the shape of tape conductor 22 is lengthCube, width are 30nm~1 μm, and the spacing of two neighboring tape conductor 22 is 30nm~1 μm.Optionally, the material of substrate 10For glass, polyethylene terephthalate or silicon.
Further, the specific method for forming conductor layer 202 is：10 surface deposited concentration of substrate be 0.5mg/L~Metal mold carbon nano-tube solution organic solvents such as (solvent be) toluene, dimethylbenzene of 30mg/L, then take out perform etching so thatConductor layer 202 is formed in substrate 10.In this way, substrate 10, which takes out air-dried rear surface, can form one layer of uniform metal mold carbon nanotubeFilm, the metal mold carbon nano-tube film for then etching removing extraneous region can be obtained conductor layer 202.It is appreciated that being formedThe mode of conductor layer 202 is without being limited thereto, can select as needed such as inkjet printing technology, spin coating, spraying.
Further, the specific method of etching conductor layer 202 is：Protection glue-line 204 is formed in conductor layer 202, is usedNanometer embossing or interference photoetching technology make protection glue-line 204 form the protection band 24 of multiple parallel intervals distribution, then intoRow is etched and washes away protection band 24 using organic solvent to form multiple tape conductors 22 of parallel interval distribution.In this way, protectionCovered part conductor layer 202 can be protected in etching process with 24, then can be obtained after organic solvent washes away band-likeConductor 22.
In one embodiment, the specific method of nanometer embossing is that a strata methyl-prop is coated in conductor layer 202E pioic acid methyl ester (PMMA) protects glue-line 204, is then heated at 65 DEG C -90 DEG C 3-15 minutes, multiple parallel with having laterThe macromolecule seal (PDMS etc.) for the nanobelt shape structure being spaced apart is stamped on softened PMMA layers, is then transferred to roomWarm environment removed macromolecule seal after 2~8 minutes, the PMMA layers of nanobelt shape structure that will form multiple parallel interval distributionsThat is protection band 24, and width (30nm-1 μm) and quantity can be adjusted according to seal structure, much smaller than the resolution limit of printing(20μm).The specific method of interference lithography is that one layer photoresist of spin coating protects glue-line 204 in conductor layer 202, is then passed throughInterference exposes and cleans the nanobelt shape structure i.e. protection band that photoresist can be made to form multiple parallel interval distributions with developer solution24, and width (30nm-1 μm) and quantity can be according to the parameter regulations of interference exposure.
In one embodiment, the specific method for forming semiconductor layer 20 is：Printing semi-conductor type carbon is received on the substrate 10Mitron ink is to form semiconductor layer 20.
In one embodiment, drain electrode 30 and source electrode 40 are formed by printing electrode ink on semiconductor layer 20, halfInsulation inks are printed in conductor layer 20 and obtain insulating layer 50, and electrode ink is printed on insulating layer 50 and obtains grid 60.Specifically,Electrode ink be metal nanoparticle ink, metal nanometer line ink, metal mold carbon nanotube ink, graphene ink and/orOrganic conductor ink.Insulation inks are organic polymer ink, inorganic, metal oxide nanoparticle inks and/or organic/nothingMachine mixes dielectric ink.
The thin film transistor (TFT) that the preparation method of present embodiment obtains reduces drain electrode the distance between 30 and source electrode 40, realLength of effective channel is reduced in matter, thus can effectively improve the current density of thin film transistor (TFT), to keep the film of printing brilliantBody pipe can also meet the driving requirement of OLED/QLED well, greatly reduce production cost and improve production efficiency.
It is specific embodiment below.
Embodiment 1
One piece of substrate of glass is taken, is cleaned using acetone, nitrogen is used in combination to dry up.Substrate is immersed in a concentration of 0.5mg/L'sIt takes out and air-dries in metal mold carbon nano-tube solution, after several minutes, then etching removes the metal mold carbon nanotube of extraneous regionFilm makes to form conductor layer in substrate.It is coated with one layer of PMMA in conductor layer and protects glue-line, 15 points are then heated at 65 DEG CThen clock is stamped in softened PMMA layers with the macromolecule seal of the nanobelt shape structure with the distribution of multiple parallel intervalsOn, room temperature environment is transferred to, after five minutes removes seal, the PMMA layers of nano strip for forming multiple parallel interval distributionsThe width of structure, that is, protection band, protection band is 30nm, and 30nm is divided between adjacent guardbands.Then at oxygen plasma etchOrganic solvent cleaning removal protection band is managed and uses, conductor layer is to form multiple tape conductors of parallel interval distribution.
Semiconductor type carbon nano-tube ink is printed in substrate, the semiconductor type carbon nano-tube for forming covering tape conductor is thinFilm, that is, semiconductor layer, tape conductor are embedded at semiconductor layer.
Source electrode, drain electrode and insulating layer are printed on the semiconductor layer, are finally printed grid on the insulating layer, are obtained film crystalPipe.
Embodiment 2
One piece of substrate of glass is taken, is cleaned using acetone, nitrogen is used in combination to dry up.Then by inkjet printing technology in substrateForm one layer of uniform metal mold carbon nano-tube film, that is, conductor layer.One layer photoresist of spin coating protects glue-line in conductor layer,It is exposed by interfering and is cleaned with developer solution, photoresist is to form the nanobelt shape structure that multiple parallel intervals are distributed to protectThe width of band, protection band is 1 μm, and 1 μm is divided between adjacent guardbands.Then it is handled and is used organic with oxygen plasma etchSolvent cleaning removal protection band, conductor layer is to form multiple tape conductors of parallel interval distribution.
Semiconductor type carbon nano-tube ink is printed in substrate, the semiconductor type carbon nano-tube for forming covering tape conductor is thinFilm, that is, semiconductor layer, tape conductor are embedded at semiconductor layer.
Source electrode, drain electrode and insulating layer are printed on the semiconductor layer, are finally printed grid on the insulating layer, are obtained film crystalPipe.
Embodiment 3
One piece of substrate of glass is taken, is cleaned using acetone, nitrogen is used in combination to dry up.Substrate is immersed in the gold of a concentration of 30mg/LIt takes out and air-dries in genotype carbon nano-tube solution, after several minutes, then the metal mold carbon nanotube of etching removing extraneous region is thinFilm makes to form conductor layer in substrate.It is coated with one layer of PMMA in conductor layer and protects glue-line, is then heated 3 minutes at 90 DEG C,Then it is stamped on softened PMMA layers with the macromolecule seal of the nanobelt shape structure with the distribution of multiple parallel intervals,Room temperature environment is transferred to, after five minutes removes seal, the PMMA layers of nanobelt shape structure for forming multiple parallel interval distributionsThat is the width of protection band, protection band is 90nm, and 30nm is divided between adjacent guardbands.Then it is handled simultaneously with oxygen plasma etchRemoval protection band is cleaned using organic solvent, conductor layer is to form multiple tape conductors of parallel interval distribution.
Semiconductor type carbon nano-tube ink is printed in substrate, the semiconductor type carbon nano-tube for forming covering tape conductor is thinFilm, that is, semiconductor layer, tape conductor are embedded at semiconductor layer.
Source electrode, drain electrode and insulating layer are printed on the semiconductor layer, are finally printed grid on the insulating layer, are obtained film crystalPipe.
Comparative example 1
One piece of substrate of glass is taken, is cleaned using acetone, nitrogen is used in combination to dry up.
Semiconductor type carbon nano-tube ink is printed in substrate, forms semiconductor type carbon nano-tube film, that is, semiconductor layer.
Source electrode, drain electrode and insulating layer are printed on the semiconductor layer, are finally printed grid on the insulating layer, are obtained film crystalPipe.
Thin film transistor (TFT) made from Examples 1 to 3 and comparative example 1 is subjected to current density detection, the results showed that embodiment 1The current density of~2 obtained thin film transistor (TFT)s is 2 times of comparative example 1, the current density for the thin film transistor (TFT) that embodiment 3 obtainsIt is 4 times of comparative example 1.
Each technical characteristic of embodiment described above can be combined arbitrarily, to keep description succinct, not to above-mentioned realityIt applies all possible combination of each technical characteristic in example to be all described, as long as however, the combination of these technical characteristics is not depositedIn contradiction, it is all considered to be the range of this specification record.
Several embodiments of the invention above described embodiment only expresses, the description thereof is more specific and detailed, but simultaneouslyIt cannot therefore be construed as limiting the scope of the patent.It should be pointed out that coming for those of ordinary skill in the artIt says, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the protection of the present inventionRange.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.